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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1807.08896 | Luca Buoninfante | Luca Buoninfante, Alan S. Cornell, Gerhard Harmsen, Alexey S.
Koshelev, Gaetano Lambiase, Jo\~ao Marto, Anupam Mazumdar | Towards nonsingular rotating compact object in ghost-free infinite
derivative gravity | 11 pages, 2 figures. Version accepted for publication in PRD | Phys. Rev. D 98, 084041 (2018) | 10.1103/PhysRevD.98.084041 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The vacuum solution of Einstein's theory of general relativity provides a
rotating metric with a ring singularity, which is covered by the inner and
outer horizons, and an ergo region. In this paper, we will discuss how
ghost-free, quadratic curvature, Infinite Derivative Gravity (IDG) may resolve
the ring singularity. In IDG the non-locality of the gravitational interaction
can smear out the delta-Dirac source distribution by making the metric
potential finite everywhere including at $r=0$. We show that the same feature
also holds for a rotating metric. We can resolve the ring singularity such that
no horizons are formed in the linear regime by smearing out a delta-source
distribution on a ring. We will also show that the Kerr-metric does not solve
the full non-linear equations of motion of ghost-free quadratic curvature IDG.
| [
{
"created": "Tue, 24 Jul 2018 04:00:29 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Nov 2018 12:45:25 GMT",
"version": "v2"
}
] | 2018-11-28 | [
[
"Buoninfante",
"Luca",
""
],
[
"Cornell",
"Alan S.",
""
],
[
"Harmsen",
"Gerhard",
""
],
[
"Koshelev",
"Alexey S.",
""
],
[
"Lambiase",
"Gaetano",
""
],
[
"Marto",
"João",
""
],
[
"Mazumdar",
"Anupam",
""
... | The vacuum solution of Einstein's theory of general relativity provides a rotating metric with a ring singularity, which is covered by the inner and outer horizons, and an ergo region. In this paper, we will discuss how ghost-free, quadratic curvature, Infinite Derivative Gravity (IDG) may resolve the ring singularity. In IDG the non-locality of the gravitational interaction can smear out the delta-Dirac source distribution by making the metric potential finite everywhere including at $r=0$. We show that the same feature also holds for a rotating metric. We can resolve the ring singularity such that no horizons are formed in the linear regime by smearing out a delta-source distribution on a ring. We will also show that the Kerr-metric does not solve the full non-linear equations of motion of ghost-free quadratic curvature IDG. |
0710.4992 | Alexei Zayats | A. B. Balakin, H. Dehnen, A. E. Zayats | Nonminimal isotropic cosmological model with Yang-Mills and Higgs fields | 15 pages, revised version accepted to Int. J. Mod. Phys. D, typos
corrected | Int.J.Mod.Phys.D17:1255-1269,2008 | 10.1142/S0218271808012802 | null | gr-qc astro-ph hep-th | null | We establish a nonminimal Einstein-Yang-Mills-Higgs model, which contains six
coupling parameters. First three parameters relate to the nonminimal coupling
of non-Abelian gauge field and gravity field, two parameters describe the
so-called derivative nonminimal coupling of scalar multiplet with gravity
field, and the sixth parameter introduces the standard coupling of scalar field
with Ricci scalar. The formulated six-parameter nonminimal
Einstein-Yang-Mills-Higgs model is applied to cosmology. We show that there
exists a unique exact cosmological solution of the de Sitter type for a special
choice of the coupling parameters. The nonminimally extended Yang-Mills and
Higgs equations are satisfied for arbitrary gauge and scalar fields, when the
coupling parameters are specifically related to the curvature constant of the
isotropic spacetime. Basing on this special exact solution we discuss the
problem of a hidden anisotropy of the Yang-Mills field, and give an explicit
example, when the nonminimal coupling effectively screens the anisotropy
induced by the Yang-Mills field and thus restores the isotropy of the model.
| [
{
"created": "Fri, 26 Oct 2007 05:44:24 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Nov 2007 10:54:49 GMT",
"version": "v2"
}
] | 2008-11-07 | [
[
"Balakin",
"A. B.",
""
],
[
"Dehnen",
"H.",
""
],
[
"Zayats",
"A. E.",
""
]
] | We establish a nonminimal Einstein-Yang-Mills-Higgs model, which contains six coupling parameters. First three parameters relate to the nonminimal coupling of non-Abelian gauge field and gravity field, two parameters describe the so-called derivative nonminimal coupling of scalar multiplet with gravity field, and the sixth parameter introduces the standard coupling of scalar field with Ricci scalar. The formulated six-parameter nonminimal Einstein-Yang-Mills-Higgs model is applied to cosmology. We show that there exists a unique exact cosmological solution of the de Sitter type for a special choice of the coupling parameters. The nonminimally extended Yang-Mills and Higgs equations are satisfied for arbitrary gauge and scalar fields, when the coupling parameters are specifically related to the curvature constant of the isotropic spacetime. Basing on this special exact solution we discuss the problem of a hidden anisotropy of the Yang-Mills field, and give an explicit example, when the nonminimal coupling effectively screens the anisotropy induced by the Yang-Mills field and thus restores the isotropy of the model. |
1805.04056 | Shuang Nan Zhang | Sheng-Xian Zhao, Shuang-Nan Zhang | Exact solutions for spherically gravitational collapse around a black
hole: the effect of tangential pressure | 14 pages, 4 figures, accepted for publication in Chinese Physics C | Chinese Physics C, Volume 42, Issue 8, article id. 085101 (2018) | 10.1088/1674-1137/42/8/085101 | null | gr-qc astro-ph.HE astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spherically gravitational collapse towards a black hole with non-zero
tangential pressure is studied. Exact solutions corresponding to different
equations of state are given. We find that when taking the tangential pressure
into account, the exact solutions have three qualitatively different endings.
For positive tangential pressure, the shell around a black hole may eventually
collapse onto the black hole, or expand to infinity, or have a static but
unstable solution, depending on the combination of black hole mass, mass of the
shell and the pressure parameter. For vanishing or negative pressure, the shell
will collapse onto the black hole. For all eventually collapsing solutions, the
shell will cross the event horizon, instead of accumulating outside the event
horizon, even if clocked by a distant stationary observer.
| [
{
"created": "Thu, 10 May 2018 16:45:30 GMT",
"version": "v1"
}
] | 2020-03-17 | [
[
"Zhao",
"Sheng-Xian",
""
],
[
"Zhang",
"Shuang-Nan",
""
]
] | Spherically gravitational collapse towards a black hole with non-zero tangential pressure is studied. Exact solutions corresponding to different equations of state are given. We find that when taking the tangential pressure into account, the exact solutions have three qualitatively different endings. For positive tangential pressure, the shell around a black hole may eventually collapse onto the black hole, or expand to infinity, or have a static but unstable solution, depending on the combination of black hole mass, mass of the shell and the pressure parameter. For vanishing or negative pressure, the shell will collapse onto the black hole. For all eventually collapsing solutions, the shell will cross the event horizon, instead of accumulating outside the event horizon, even if clocked by a distant stationary observer. |
1202.6311 | T. Damour | Thibault Damour | Theoretical Aspects of the Equivalence Principle | 21 pages, no figures; submitted to a "focus issue" of Classical and
Quantum Gravity on Tests of the Weak Equivalence Principle, organized by
Clive Speake and Clifford Will | null | 10.1088/0264-9381/29/18/184001 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review several theoretical aspects of the Equivalence Principle (EP). We
emphasize the unsatisfactory fact that the EP maintains the absolute character
of the coupling constants of physics while General Relativity, and its
generalizations (Kaluza-Klein,..., String Theory), suggest that all absolute
structures should be replaced by dynamical entities. We discuss the
EP-violation phenomenology of dilaton-like models, which is likely to be
dominated by the linear superposition of two effects: a signal proportional to
the nuclear Coulomb energy, related to the variation of the fine-structure
constant, and a signal proportional to the surface nuclear binding energy,
related to the variation of the light quark masses. We recall the various
theoretical arguments (including a recently proposed anthropic argument)
suggesting that the EP be violated at a small, but not unmeasurably small
level. This motivates the need for improved tests of the EP. These tests are
probing new territories in physics that are related to deep, and mysterious,
issues in fundamental physics.
| [
{
"created": "Tue, 28 Feb 2012 18:12:16 GMT",
"version": "v1"
}
] | 2015-06-04 | [
[
"Damour",
"Thibault",
""
]
] | We review several theoretical aspects of the Equivalence Principle (EP). We emphasize the unsatisfactory fact that the EP maintains the absolute character of the coupling constants of physics while General Relativity, and its generalizations (Kaluza-Klein,..., String Theory), suggest that all absolute structures should be replaced by dynamical entities. We discuss the EP-violation phenomenology of dilaton-like models, which is likely to be dominated by the linear superposition of two effects: a signal proportional to the nuclear Coulomb energy, related to the variation of the fine-structure constant, and a signal proportional to the surface nuclear binding energy, related to the variation of the light quark masses. We recall the various theoretical arguments (including a recently proposed anthropic argument) suggesting that the EP be violated at a small, but not unmeasurably small level. This motivates the need for improved tests of the EP. These tests are probing new territories in physics that are related to deep, and mysterious, issues in fundamental physics. |
2112.11309 | Vladimir Kassandrov | Ahmed Alharthy and Vladimir V. Kassandrov | On a Crucial Role of Gravity in the Formation of Elementary Particles | 17 pages, 9 figures | Universe 2020, 6(11), 193 | 10.3390/universe6110193 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We consider the model of minimally interacting electromagnetic, gravitational
and massive scalar fields free of any additional nonlinearities. In the
dimensionless form, the Lagranginan contains only one parameter \gamma =
Gm^2/e^2 which corresponds to the ratio of gravitational and electromagnetic
interactions and, for a typical elementary particle, is about 10^-40. However,
regular (soliton-like) solutions can exist only for \gamma \ne 0 so that
gravity would be necessary to form the structure of an (extended) elementary
particle. Unfortunately (in the stationary spherically symmetrical case), the
numerical procedure breaks in the range \gamma \le 0.9 so that whether the
particle-like solutions actually exist in the model remains unclear.
Nonetheless, for \gamma \approx 1, we obtain, making use of the minimal energy
requirement, a discrete set of (horizon-free) electrically charged regular
solutions of the Planck's range mass and dimensions ("maximons", "planckeons",
etc.). In the limit \gamma \to \infty the model reduces to the well known
coupled system of the Einstein and Klein-Gordon equations. We obtain -- to our
knowledge -- for the first time, the discrete spectrum of neutral soliton-like
solutions ("mini-boson stars", "soliton stars", etc.)
%
| [
{
"created": "Tue, 21 Dec 2021 15:57:44 GMT",
"version": "v1"
}
] | 2021-12-22 | [
[
"Alharthy",
"Ahmed",
""
],
[
"Kassandrov",
"Vladimir V.",
""
]
] | We consider the model of minimally interacting electromagnetic, gravitational and massive scalar fields free of any additional nonlinearities. In the dimensionless form, the Lagranginan contains only one parameter \gamma = Gm^2/e^2 which corresponds to the ratio of gravitational and electromagnetic interactions and, for a typical elementary particle, is about 10^-40. However, regular (soliton-like) solutions can exist only for \gamma \ne 0 so that gravity would be necessary to form the structure of an (extended) elementary particle. Unfortunately (in the stationary spherically symmetrical case), the numerical procedure breaks in the range \gamma \le 0.9 so that whether the particle-like solutions actually exist in the model remains unclear. Nonetheless, for \gamma \approx 1, we obtain, making use of the minimal energy requirement, a discrete set of (horizon-free) electrically charged regular solutions of the Planck's range mass and dimensions ("maximons", "planckeons", etc.). In the limit \gamma \to \infty the model reduces to the well known coupled system of the Einstein and Klein-Gordon equations. We obtain -- to our knowledge -- for the first time, the discrete spectrum of neutral soliton-like solutions ("mini-boson stars", "soliton stars", etc.) % |
2311.08616 | Erick Ivan Duque Gonzalez | Erick I. Duque | Emergent modified gravity: The perfect fluid and gravitational collapse | 49 pages, 7 figures; added references, typos corrected | null | 10.1103/PhysRevD.109.044014 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Emergent modified gravity is a canonical theory based on general covariance
where the spacetime is not fundamental, but rather an emergent object. This
feature allows for modifications of the classical theory and can be used to
model new effects, such as those suggested by quantum gravity. We discuss how
matter fields can be coupled to emergent modified gravity, realize the coupling
of the perfect fluid, identify the symmetries of the system, and explicitly
obtain the Hamiltonian in spherical symmetry. We formulate the
Oppenheimer-Snyder collapse model in canonical terms, permitting us to extend
the model to emergent modified gravity and obtain an exact solution to the dust
collapsing from spatial infinity including some effects suggested by quantum
gravity. In this solution the collapsing dust forms a black hole, then the star
radius reaches a minimum with vanishing velocity and finite positive
acceleration, and proceeds to emerge out now behaving as a white hole. While
the geometry on the minimum-radius surface is regular in the vacuum, it is
singular in the presence of dust. However, the fact that the geometry is
emergent, and the fundamental fields that compose the phase-space are regular,
allows us to continue the canonical solution in a meaningful way, obtaining the
global structure for the interior of the star. The star-interior solution is
complemented by the vacuum solution describing the star-exterior region by a
continuous junction at the star radius. This gluing process can be viewed as
the imposition of boundary conditions, which is non-unique and does not follow
from the equations of motion. This ambiguity gives rise to different possible
physical outcomes of the collapse. We discuss two such phenomena: the formation
of a wormhole and the transition from a black hole to a white hole.
| [
{
"created": "Wed, 15 Nov 2023 00:46:44 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Jan 2024 19:06:50 GMT",
"version": "v2"
}
] | 2024-02-06 | [
[
"Duque",
"Erick I.",
""
]
] | Emergent modified gravity is a canonical theory based on general covariance where the spacetime is not fundamental, but rather an emergent object. This feature allows for modifications of the classical theory and can be used to model new effects, such as those suggested by quantum gravity. We discuss how matter fields can be coupled to emergent modified gravity, realize the coupling of the perfect fluid, identify the symmetries of the system, and explicitly obtain the Hamiltonian in spherical symmetry. We formulate the Oppenheimer-Snyder collapse model in canonical terms, permitting us to extend the model to emergent modified gravity and obtain an exact solution to the dust collapsing from spatial infinity including some effects suggested by quantum gravity. In this solution the collapsing dust forms a black hole, then the star radius reaches a minimum with vanishing velocity and finite positive acceleration, and proceeds to emerge out now behaving as a white hole. While the geometry on the minimum-radius surface is regular in the vacuum, it is singular in the presence of dust. However, the fact that the geometry is emergent, and the fundamental fields that compose the phase-space are regular, allows us to continue the canonical solution in a meaningful way, obtaining the global structure for the interior of the star. The star-interior solution is complemented by the vacuum solution describing the star-exterior region by a continuous junction at the star radius. This gluing process can be viewed as the imposition of boundary conditions, which is non-unique and does not follow from the equations of motion. This ambiguity gives rise to different possible physical outcomes of the collapse. We discuss two such phenomena: the formation of a wormhole and the transition from a black hole to a white hole. |
2208.03572 | Donato Bini | Donato Bini, Stuart Kauffman, Sauro Succi, Pablo G. Tello | First Post-Minkowskian approach to turbulent gravity | 11 pages; 5 figures | null | 10.1103/PhysRevD.106.104007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the metric fluctuations induced by a turbulent energy-matter
tensor within the first order Post-Minkowskian approximation. It is found that
the turbulent energy cascade can in principle interfere with the process of
black hole formation, leading to a potentially strong coupling between these
two highly nonlinear phenomena. It is further found that a power-law turbulent
energy spectrum $E(k) \sim k^{-n}$ generates metric fluctuations scaling like
$x^{n-2}$, where $x$ is a four-dimensional distance from an arbitrary origin in
spacetime. This highlights the onset of metric singularities whenever $n <2$,
meaning that $2d$ fluid turbulence ($n=3$) yields smooth %(differentiable)
metric fluctuations, scaling like $x$, while $3d$ turbulence ($n=5/3$) yields a
weakly singular metric $x^{-1/3}$and purely random fluctuations, $n=1$,
generate a stronger $1/x$ singularity. Finally, the effect of metric
fluctuations on the geodesic motion of test particles is also discussed as a
potential technique to extract information on the spectral characteristics of
fluctuating spacetime.
| [
{
"created": "Sat, 6 Aug 2022 19:56:43 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Sep 2022 09:18:15 GMT",
"version": "v2"
}
] | 2022-11-16 | [
[
"Bini",
"Donato",
""
],
[
"Kauffman",
"Stuart",
""
],
[
"Succi",
"Sauro",
""
],
[
"Tello",
"Pablo G.",
""
]
] | We compute the metric fluctuations induced by a turbulent energy-matter tensor within the first order Post-Minkowskian approximation. It is found that the turbulent energy cascade can in principle interfere with the process of black hole formation, leading to a potentially strong coupling between these two highly nonlinear phenomena. It is further found that a power-law turbulent energy spectrum $E(k) \sim k^{-n}$ generates metric fluctuations scaling like $x^{n-2}$, where $x$ is a four-dimensional distance from an arbitrary origin in spacetime. This highlights the onset of metric singularities whenever $n <2$, meaning that $2d$ fluid turbulence ($n=3$) yields smooth %(differentiable) metric fluctuations, scaling like $x$, while $3d$ turbulence ($n=5/3$) yields a weakly singular metric $x^{-1/3}$and purely random fluctuations, $n=1$, generate a stronger $1/x$ singularity. Finally, the effect of metric fluctuations on the geodesic motion of test particles is also discussed as a potential technique to extract information on the spectral characteristics of fluctuating spacetime. |
2012.03342 | Juan M. Z\'arate Pretel | Juan M. Z. Pretel, Sergio E. Jor\'as, Ribamar R. R. Reis and Jos\'e D.
V. Arba\~nil | Radial oscillations and stability of compact stars in $f(R, T) = R+
2\beta T$ gravity | Accepted for publication in JCAP; 18 pages, 6 figures and new
references added | JCAP 04 (2021) 064 | 10.1088/1475-7516/2021/04/064 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the static structure configurations and radial stability of
compact stars within the context of $f(R, T)$ gravity, with $R$ and $T$
standing for the Ricci scalar and trace of the energy-momentum tensor,
respectively. Considering the $f(R, T)=R+2\beta T$ functional form, with
$\beta$ being a constant, we derive the corresponding hydrostatic equilibrium
equation and the modified Chandrasekhar's pulsation equation. The mass-radius
relations and radial mode frequencies are obtained for some realistic equations
of state. Our results show that the traditional stellar stability criteria,
namely, the necessary condition $dM/d\rho_c >0$ and sufficient condition
$\omega^2 >0$, still hold in this theory of gravity.
| [
{
"created": "Sun, 6 Dec 2020 17:59:27 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Mar 2021 19:42:58 GMT",
"version": "v2"
}
] | 2021-04-26 | [
[
"Pretel",
"Juan M. Z.",
""
],
[
"Jorás",
"Sergio E.",
""
],
[
"Reis",
"Ribamar R. R.",
""
],
[
"Arbañil",
"José D. V.",
""
]
] | We examine the static structure configurations and radial stability of compact stars within the context of $f(R, T)$ gravity, with $R$ and $T$ standing for the Ricci scalar and trace of the energy-momentum tensor, respectively. Considering the $f(R, T)=R+2\beta T$ functional form, with $\beta$ being a constant, we derive the corresponding hydrostatic equilibrium equation and the modified Chandrasekhar's pulsation equation. The mass-radius relations and radial mode frequencies are obtained for some realistic equations of state. Our results show that the traditional stellar stability criteria, namely, the necessary condition $dM/d\rho_c >0$ and sufficient condition $\omega^2 >0$, still hold in this theory of gravity. |
2202.09794 | Subhajit Saha | Subhajit Saha, Abdulla Al Mamon, Somnath Saha | Evolution of primordial black holes in an adiabatic FLRW universe with
gravitational particle creation | 10 pages, 1 figure, 3 tables, Revised as per suggestions of the
reviewer | General Relativity and Gravitation 54, 122 (2022) | 10.1007/s10714-022-03010-6 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the evolution of primordial black holes (PBHs) in an adiabatic FLRW
universe with dissipation due to bulk viscosity which is considered to be in
the form of gravitational particle creation. Assuming that the process of
evaporation is quite suppressed during the radiation era, we obtain an analytic
solution for the evolution of PBH mass by accretion during this era, subject to
an initial condition. We also obtain an upper bound on the accretion efficiency
$\epsilon$ for $a \sim a_r$, where $a_r$ is the point of transition from the
early de Sitter era to the radiation era. Furthermore, we obtain numerical
solutions for the mass of a hypothetical PBH with initial mass 100 g assumed to
be formed at an epoch when the value of the Hubble parameter was, say, 1
km/s/Mpc. We consider three values of the accretion efficiency,
$\epsilon=0.23,0.5$, and $0.89$ for our study. The analysis reveals that the
mass of the PBH increases rapidly due to the accretion of radiation in the
early stages of its evolution. The accretion continues but its rate decreases
gradually with the evolution of the Universe. Finally, Hawking radiation comes
into play and the rate of evaporation surpasses the accretion rate so that the
PBH mass starts to decrease. As the Universe grows, evaporation becomes the
dominant phenomenon, and the mass of the PBH decreases at a faster rate. As
argued by Debnath and Paul, the evaporated mass of the PBHs might contribute
towards the dark energy budget of the late Universe.
| [
{
"created": "Sun, 20 Feb 2022 11:31:50 GMT",
"version": "v1"
},
{
"created": "Sat, 15 Oct 2022 16:33:16 GMT",
"version": "v2"
}
] | 2022-10-18 | [
[
"Saha",
"Subhajit",
""
],
[
"Mamon",
"Abdulla Al",
""
],
[
"Saha",
"Somnath",
""
]
] | We study the evolution of primordial black holes (PBHs) in an adiabatic FLRW universe with dissipation due to bulk viscosity which is considered to be in the form of gravitational particle creation. Assuming that the process of evaporation is quite suppressed during the radiation era, we obtain an analytic solution for the evolution of PBH mass by accretion during this era, subject to an initial condition. We also obtain an upper bound on the accretion efficiency $\epsilon$ for $a \sim a_r$, where $a_r$ is the point of transition from the early de Sitter era to the radiation era. Furthermore, we obtain numerical solutions for the mass of a hypothetical PBH with initial mass 100 g assumed to be formed at an epoch when the value of the Hubble parameter was, say, 1 km/s/Mpc. We consider three values of the accretion efficiency, $\epsilon=0.23,0.5$, and $0.89$ for our study. The analysis reveals that the mass of the PBH increases rapidly due to the accretion of radiation in the early stages of its evolution. The accretion continues but its rate decreases gradually with the evolution of the Universe. Finally, Hawking radiation comes into play and the rate of evaporation surpasses the accretion rate so that the PBH mass starts to decrease. As the Universe grows, evaporation becomes the dominant phenomenon, and the mass of the PBH decreases at a faster rate. As argued by Debnath and Paul, the evaporated mass of the PBHs might contribute towards the dark energy budget of the late Universe. |
2105.11261 | Julio Arrechea | Julio Arrechea, Carlos Barcel\'o, Ra\'ul Carballo-Rubio, Luis J. Garay | Semiclassical constant-density spheres in a regularized Polyakov
approximation | 35 pages, 20 figures. There is a new figure containing numerical
integrations for every solution in the catalogue. We included a Mathematica
notebook to reproduce such plots. A typo in Eq. (59) has been fixed.
References added | null | 10.1103/PhysRevD.104.084071 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide an exhaustive analysis of the complete set of solutions of the
equations of stellar equilibrium under semiclassical effects. As classical
matter we use a perfect fluid of constant density; as the semiclassical source
we use the renormalized stress-energy tensor (RSET) of a minimally coupled
massless scalar field in the Boulware vacuum (the only vacuum consistent with
asymptotic flatness and staticity). For the RSET we use a regularized version
of the Polyakov approximation. We present a complete catalogue of the
semiclassical self-consistent solutions which incorporates regular as well as
singular solutions, showing that the semiclassical corrections are highly
relevant in scenarios of high compactness. Semiclassical corrections allow the
existence of ultra-compact equilibrium configurations which have bounded
pressures and masses up to a central core of Planckian radius, precisely where
the regularized Polyakov approximation is not accurate. Our analysis strongly
suggests the absence of a Buchdahl limit in semiclasical gravity, while
indicating that the regularized Polyakov approximation used here must be
improved to describe equilibrium configurations of arbitrary compactness that
remain regular at the center of spherical symmetry.
| [
{
"created": "Mon, 24 May 2021 13:28:13 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Oct 2021 10:18:57 GMT",
"version": "v2"
}
] | 2021-10-22 | [
[
"Arrechea",
"Julio",
""
],
[
"Barceló",
"Carlos",
""
],
[
"Carballo-Rubio",
"Raúl",
""
],
[
"Garay",
"Luis J.",
""
]
] | We provide an exhaustive analysis of the complete set of solutions of the equations of stellar equilibrium under semiclassical effects. As classical matter we use a perfect fluid of constant density; as the semiclassical source we use the renormalized stress-energy tensor (RSET) of a minimally coupled massless scalar field in the Boulware vacuum (the only vacuum consistent with asymptotic flatness and staticity). For the RSET we use a regularized version of the Polyakov approximation. We present a complete catalogue of the semiclassical self-consistent solutions which incorporates regular as well as singular solutions, showing that the semiclassical corrections are highly relevant in scenarios of high compactness. Semiclassical corrections allow the existence of ultra-compact equilibrium configurations which have bounded pressures and masses up to a central core of Planckian radius, precisely where the regularized Polyakov approximation is not accurate. Our analysis strongly suggests the absence of a Buchdahl limit in semiclasical gravity, while indicating that the regularized Polyakov approximation used here must be improved to describe equilibrium configurations of arbitrary compactness that remain regular at the center of spherical symmetry. |
1705.11015 | H\'el\`ene Pihan-Le Bars | H. Pihan-Le Bars, C. Guerlin and P. Wolf | Progress on testing Lorentz symmetry with MICROSCOPE | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Weak Equivalence Principle (WEP) and the local Lorentz invariance (LLI)
are two major assumptions of General Relativity (GR). The MICROSCOPE mission,
currently operating, will perform a test of the WEP with a precision of
$10^{-15}$. The data will also be analysed at SYRTE for the purposes of a LLI
test realised in collaboration with J. Tasson (Carleton College, Minnesota) and
Q. Bailey (Embry-Riddle Aeronautical University, Arizona). This study will be
performed in a general framework, called the Standard Model Extension (SME),
describing Lorentz violations that could appear at Planck scale ($10^{19}$
GeV). The SME allows us to derive a Lorentz violating observable designed for
the MICROSCOPE experiment and to search for possible deviations from LLI in the
differential acceleration of the test masses.
| [
{
"created": "Wed, 31 May 2017 10:14:48 GMT",
"version": "v1"
}
] | 2017-06-01 | [
[
"Bars",
"H. Pihan-Le",
""
],
[
"Guerlin",
"C.",
""
],
[
"Wolf",
"P.",
""
]
] | The Weak Equivalence Principle (WEP) and the local Lorentz invariance (LLI) are two major assumptions of General Relativity (GR). The MICROSCOPE mission, currently operating, will perform a test of the WEP with a precision of $10^{-15}$. The data will also be analysed at SYRTE for the purposes of a LLI test realised in collaboration with J. Tasson (Carleton College, Minnesota) and Q. Bailey (Embry-Riddle Aeronautical University, Arizona). This study will be performed in a general framework, called the Standard Model Extension (SME), describing Lorentz violations that could appear at Planck scale ($10^{19}$ GeV). The SME allows us to derive a Lorentz violating observable designed for the MICROSCOPE experiment and to search for possible deviations from LLI in the differential acceleration of the test masses. |
1502.03071 | Hor\'acio Santana Vieira | H. S. Vieira, V. B. Bezerra | Quantum Newtonian cosmology and the biconfluent Heun functions | 15 pages, 2 figures | J. Math. Phys. 56, 092501 (2015) | 10.1063/1.4930871 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain the exact solution of the Schr\"odinger equation for a particle
(galaxy) moving in a Newtonian universe with a cosmological constant, which is
given in terms of the biconfluent Heun functions. The first six Heun
polynomials of the biconfluent function are written explicitly. The energy
spectrum which resembles the one corresponding to the isotropic harmonic
oscillator is also obtained. The wave functions as well as the energy levels
codify the role played by the cosmological constant.
| [
{
"created": "Tue, 10 Feb 2015 20:23:57 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Sep 2015 14:00:57 GMT",
"version": "v2"
}
] | 2015-09-16 | [
[
"Vieira",
"H. S.",
""
],
[
"Bezerra",
"V. B.",
""
]
] | We obtain the exact solution of the Schr\"odinger equation for a particle (galaxy) moving in a Newtonian universe with a cosmological constant, which is given in terms of the biconfluent Heun functions. The first six Heun polynomials of the biconfluent function are written explicitly. The energy spectrum which resembles the one corresponding to the isotropic harmonic oscillator is also obtained. The wave functions as well as the energy levels codify the role played by the cosmological constant. |
0909.0010 | Eiichi Hirose | Eiichi Hirose, Keita Kawabe, Daniel Sigg, Rana Adhikari, and Peter R.
Saulson | Angular instability due to radiation pressure in the LIGO gravitational
wave detector | Submitted to Applied Optics | null | 10.1364/AO.49.003474 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We observed the effect of radiation pressure on the angular sensing and
control system of the Laser Interferometer Gravitational-Wave Observatory
(LIGO) interferometer's core optics at LIGO Hanford Observatory. This is the
first measurement of this effect in a complete gravitational wave
interferometer. Only one of the two angular modes survives with feedback
control, since the other mode is suppressed when the control gain is
sufficiently large. We developed a mathematical model to understand the physics
of the system. This model matches well the dynamics that we observe.
| [
{
"created": "Mon, 31 Aug 2009 20:01:46 GMT",
"version": "v1"
}
] | 2015-05-14 | [
[
"Hirose",
"Eiichi",
""
],
[
"Kawabe",
"Keita",
""
],
[
"Sigg",
"Daniel",
""
],
[
"Adhikari",
"Rana",
""
],
[
"Saulson",
"Peter R.",
""
]
] | We observed the effect of radiation pressure on the angular sensing and control system of the Laser Interferometer Gravitational-Wave Observatory (LIGO) interferometer's core optics at LIGO Hanford Observatory. This is the first measurement of this effect in a complete gravitational wave interferometer. Only one of the two angular modes survives with feedback control, since the other mode is suppressed when the control gain is sufficiently large. We developed a mathematical model to understand the physics of the system. This model matches well the dynamics that we observe. |
0810.4529 | Lee Samuel Finn | Lee Samuel Finn | The response of interferometric gravitational wave detectors | 10 pages, one figure, as accepted to PRD | Phys.Rev.D79:022002,2009 | 10.1103/PhysRevD.79.022002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The derivation of the response function of an interferometric gravitational
wave detector is a paradigmatic calculation in the field of gravitational wave
detection. Surprisingly, the standard derivation of the response wave detectors
makes several unjustifiable assumptions, both conceptual and quantitative,
regarding the coordinate trajectory and coordinate velocity of the null
geodesic the light travels along. These errors, which appear to have remained
unrecognized for at least 35 years, render the "standard" derivation inadequate
and misleading as an archetype calculation. Here we identify the flaws in the
existing derivation and provide, in full detail, a correct derivation of the
response of a single-bounce Michelson interferometer to gravitational waves,
following a procedure that will always yield correct results; compare it to the
"standard", but incorrect, derivation; show where the earlier mistakes were
made; and identify the general conditions under which the "standard" derivation
will yield correct results. By a fortuitous set of circumstances, not generally
so, the final result is the same in the case of Minkowski background spacetime,
synchronous coordinates, transverse-traceless gauge metric perturbations, and
arm mirrors at coordinate rest.
| [
{
"created": "Fri, 24 Oct 2008 19:12:32 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Jan 2009 17:37:26 GMT",
"version": "v2"
}
] | 2010-04-21 | [
[
"Finn",
"Lee Samuel",
""
]
] | The derivation of the response function of an interferometric gravitational wave detector is a paradigmatic calculation in the field of gravitational wave detection. Surprisingly, the standard derivation of the response wave detectors makes several unjustifiable assumptions, both conceptual and quantitative, regarding the coordinate trajectory and coordinate velocity of the null geodesic the light travels along. These errors, which appear to have remained unrecognized for at least 35 years, render the "standard" derivation inadequate and misleading as an archetype calculation. Here we identify the flaws in the existing derivation and provide, in full detail, a correct derivation of the response of a single-bounce Michelson interferometer to gravitational waves, following a procedure that will always yield correct results; compare it to the "standard", but incorrect, derivation; show where the earlier mistakes were made; and identify the general conditions under which the "standard" derivation will yield correct results. By a fortuitous set of circumstances, not generally so, the final result is the same in the case of Minkowski background spacetime, synchronous coordinates, transverse-traceless gauge metric perturbations, and arm mirrors at coordinate rest. |
2301.03004 | Yan-Gang Miao | Yang Guo, Hao Xie, Yan-Gang Miao | Joule-Thomson effect of AdS black holes in conformal gravity | v1: 10 pages, 4 figures; v2: 11 pages, clarifications and references
added, final version to appear in Nuclear Physics B | Nucl. Phys. B 993 (2023) 116280 (10 pages) | 10.1016/j.nuclphysb.2023.116280 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the Joule-Thomson effect of AdS black holes in conformal
gravity. We derive the Joule-Thomson coefficient in terms of thermodynamic
relations and then make an alternative derivation via a direct way. We analyze
the Joule-Thomson coefficient and find that the Joule-Thomson coefficients
obtained from two different approaches are equal. Moreover, we present a novel
isenthalpic process in which the inversion temperature is minimal and it
separates the corresponding heating-cooling phase. We analyze the inversion
temperature and its corresponding inversion curve that separates the regions
for the JT effect to be allowable and forbidden, where such an effect can only
be observed in the allowable region. We also discuss the effects of two
important parameters on the inversion curves.
| [
{
"created": "Sun, 8 Jan 2023 09:17:51 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Jun 2023 00:25:53 GMT",
"version": "v2"
}
] | 2023-06-28 | [
[
"Guo",
"Yang",
""
],
[
"Xie",
"Hao",
""
],
[
"Miao",
"Yan-Gang",
""
]
] | We investigate the Joule-Thomson effect of AdS black holes in conformal gravity. We derive the Joule-Thomson coefficient in terms of thermodynamic relations and then make an alternative derivation via a direct way. We analyze the Joule-Thomson coefficient and find that the Joule-Thomson coefficients obtained from two different approaches are equal. Moreover, we present a novel isenthalpic process in which the inversion temperature is minimal and it separates the corresponding heating-cooling phase. We analyze the inversion temperature and its corresponding inversion curve that separates the regions for the JT effect to be allowable and forbidden, where such an effect can only be observed in the allowable region. We also discuss the effects of two important parameters on the inversion curves. |
1205.5311 | Roman Konoplya | R. A. Konoplya, Yu-Chun Liu | Motion of charged particles and quasinormal modes around the
magnetically and tidally deformed black hole | 15 pages, RevTex, improved style, minor changes | Phys.Rev. D86 (2012) 084007 | 10.1103/PhysRevD.86.084007 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Here we consider two phenomena in the vicinity of a black hole deformed by
the tidal gravitational force of surrounding matter and by a strong magnetic
field: equatorial motion of charged particles and the decay of a test scalar
field. We were able to analyze both phenomena with analytical and simple
numerical tools, which was unexpected given the low symmetry of the system. We
show that both the tidal gravitational force and the magnetic field strongly
enhance the release of the binding energy for the matter spiralling into the
black hole. In the presence of the magnetic field, the left and right handed
rotations of charged particles are not equivalent and for sufficiently large
$|q| B$ there are stable anti-Larmor orbits very close to the event horizon,
although Larmor orbits are only stable at some distance from the black hole.
The larger the tidal force, the closer the innermost stable orbit to the black
hole for both types of rotation. It was also shown that the real oscillation
frequencies of the characteristic quasinormal modes are considerably suppressed
by the tidal force.
| [
{
"created": "Thu, 24 May 2012 00:22:44 GMT",
"version": "v1"
},
{
"created": "Sun, 1 Jul 2012 22:15:55 GMT",
"version": "v2"
},
{
"created": "Wed, 8 Aug 2012 20:29:59 GMT",
"version": "v3"
}
] | 2015-03-20 | [
[
"Konoplya",
"R. A.",
""
],
[
"Liu",
"Yu-Chun",
""
]
] | Here we consider two phenomena in the vicinity of a black hole deformed by the tidal gravitational force of surrounding matter and by a strong magnetic field: equatorial motion of charged particles and the decay of a test scalar field. We were able to analyze both phenomena with analytical and simple numerical tools, which was unexpected given the low symmetry of the system. We show that both the tidal gravitational force and the magnetic field strongly enhance the release of the binding energy for the matter spiralling into the black hole. In the presence of the magnetic field, the left and right handed rotations of charged particles are not equivalent and for sufficiently large $|q| B$ there are stable anti-Larmor orbits very close to the event horizon, although Larmor orbits are only stable at some distance from the black hole. The larger the tidal force, the closer the innermost stable orbit to the black hole for both types of rotation. It was also shown that the real oscillation frequencies of the characteristic quasinormal modes are considerably suppressed by the tidal force. |
gr-qc/9911073 | M. Meyer | S. Deser | Infinities in Quantum Gravities | 8 pages. Plenary lecture at Journees Relativistes 1999 | AnnalenPhys.9:299-307,2000 | 10.1002/(SICI)1521-3889(200005)9:3/5<299::AID-ANDP299>3.0.CO;2-E | BRX TH-464 | gr-qc hep-th | null | We first present a review, intended for classical relativists, of the
ultraviolet difficulties faced by local quantum gravity theories in both the
usual Einstein versions and in their supergravity extensions, at least
perturbatively. These problems, present in arbitrary dimensions, are traceable
to the dimensionality of the Einstein constant. We then summarize very recent
results about supergravity at the highest allowed dimension, D=11, showing that
also this unique model suffers from infinities already at 2 loops, despite its
high degree of supersymmetry. The conclusion is that there is no viable
nonghost quantum field model that includes general relativity.
| [
{
"created": "Fri, 19 Nov 1999 15:43:13 GMT",
"version": "v1"
}
] | 2017-09-27 | [
[
"Deser",
"S.",
""
]
] | We first present a review, intended for classical relativists, of the ultraviolet difficulties faced by local quantum gravity theories in both the usual Einstein versions and in their supergravity extensions, at least perturbatively. These problems, present in arbitrary dimensions, are traceable to the dimensionality of the Einstein constant. We then summarize very recent results about supergravity at the highest allowed dimension, D=11, showing that also this unique model suffers from infinities already at 2 loops, despite its high degree of supersymmetry. The conclusion is that there is no viable nonghost quantum field model that includes general relativity. |
1905.09300 | Vijay Varma | Vijay Varma, Scott E. Field, Mark A. Scheel, Jonathan Blackman, Davide
Gerosa, Leo C. Stein, Lawrence E. Kidder, and Harald P. Pfeiffer | Surrogate models for precessing binary black hole simulations with
unequal masses | Matches published version. Models publicly available at
https://zenodo.org/record/3455886#.XZ9s1-dKjBI and
https://pypi.org/project/surfinBH | Phys. Rev. Research 1, 033015 (2019) | 10.1103/PhysRevResearch.1.033015 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Only numerical relativity simulations can capture the full complexities of
binary black hole mergers. These simulations, however, are prohibitively
expensive for direct data analysis applications such as parameter estimation.
We present two new fast and accurate surrogate models for the outputs of these
simulations: the first model, NRSur7dq4, predicts the gravitational waveform
and the second model, \RemnantModel, predicts the properties of the remnant
black hole. These models extend previous 7-dimensional, non-eccentric
precessing models to higher mass ratios, and have been trained against 1528
simulations with mass ratios $q\leq4$ and spin magnitudes $\chi_1,\chi_2 \leq
0.8$, with generic spin directions. The waveform model, NRSur7dq4, which begins
about 20 orbits before merger, includes all $\ell \leq 4$ spin-weighted
spherical harmonic modes, as well as the precession frame dynamics and spin
evolution of the black holes. The final black hole model, \RemnantModel, models
the mass, spin, and recoil kick velocity of the remnant black hole. In their
training parameter range, both models are shown to be more accurate than
existing models by at least an order of magnitude, with errors comparable to
the estimated errors in the numerical relativity simulations. We also show that
the surrogate models work well even when extrapolated outside their training
parameter space range, up to mass ratios $q=6$.
| [
{
"created": "Wed, 22 May 2019 18:00:11 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jul 2019 01:30:06 GMT",
"version": "v2"
},
{
"created": "Thu, 10 Oct 2019 17:46:24 GMT",
"version": "v3"
}
] | 2019-10-16 | [
[
"Varma",
"Vijay",
""
],
[
"Field",
"Scott E.",
""
],
[
"Scheel",
"Mark A.",
""
],
[
"Blackman",
"Jonathan",
""
],
[
"Gerosa",
"Davide",
""
],
[
"Stein",
"Leo C.",
""
],
[
"Kidder",
"Lawrence E.",
""
],
... | Only numerical relativity simulations can capture the full complexities of binary black hole mergers. These simulations, however, are prohibitively expensive for direct data analysis applications such as parameter estimation. We present two new fast and accurate surrogate models for the outputs of these simulations: the first model, NRSur7dq4, predicts the gravitational waveform and the second model, \RemnantModel, predicts the properties of the remnant black hole. These models extend previous 7-dimensional, non-eccentric precessing models to higher mass ratios, and have been trained against 1528 simulations with mass ratios $q\leq4$ and spin magnitudes $\chi_1,\chi_2 \leq 0.8$, with generic spin directions. The waveform model, NRSur7dq4, which begins about 20 orbits before merger, includes all $\ell \leq 4$ spin-weighted spherical harmonic modes, as well as the precession frame dynamics and spin evolution of the black holes. The final black hole model, \RemnantModel, models the mass, spin, and recoil kick velocity of the remnant black hole. In their training parameter range, both models are shown to be more accurate than existing models by at least an order of magnitude, with errors comparable to the estimated errors in the numerical relativity simulations. We also show that the surrogate models work well even when extrapolated outside their training parameter space range, up to mass ratios $q=6$. |
2311.10562 | Erik Aurell | Erik Aurell, Lucas Hackl, Pawe{\l} Horodecki, Robert H. Jonsson, Mario
Kieburg | Random pure Gaussian states and Hawking radiation | Published version, with supplementary material. Main paper 7 pages, 3
figures. Supplementary material 30 pages, 1 figure | Phys. Rev. Lett. 133, 060202 (2024) | 10.1103/PhysRevLett.133.060202 | NORDITA 2023-094 (for co-author RHJ) | gr-qc cond-mat.stat-mech quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A black hole evaporates by Hawking radiation. Each mode of that radiation is
thermal. If the total state is nevertheless to be pure, modes must be
entangled. Estimating the minimum size of this entanglement has been an
important outstanding issue. We develop a new theory of constrained random
symplectic transformations, based on that the total state is pure and Gaussian
with given marginals. In the random constrained symplectic model we then
compute the distribution of mode-mode correlations, from which we bound
mode-mode entanglement. Modes of frequency much larger than $\frac{k_B
T_{H}(t)}{\hbar}$ are not populated at time $t$ and drop out of the
analysis.Among the other modes we find that correlations and hence entanglement
between relatively thinly populated modes (early-time high-frequency modes
and/or late modes of any frequency) to be strongly suppressed. Relatively
highly populated modes (early-time low-frequency modes) can on the other hand
be strongly correlated, but a detailed analysis reveals that they are
nevertheless very unlikely to be entangled. Our analysis hence establishes that
restoring unitarity after a complete evaporation of a black hole does not
require any significant quantum entanglement between any pair of Hawking modes.
Our analysis further gives exact general expressions for the distribution of
mode-mode correlations in random, pure, Gaussian states with given marginals,
which may have applications beyond black hole physics.
| [
{
"created": "Fri, 17 Nov 2023 14:54:03 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Dec 2023 12:44:42 GMT",
"version": "v2"
},
{
"created": "Wed, 7 Aug 2024 19:47:33 GMT",
"version": "v3"
}
] | 2024-08-09 | [
[
"Aurell",
"Erik",
""
],
[
"Hackl",
"Lucas",
""
],
[
"Horodecki",
"Paweł",
""
],
[
"Jonsson",
"Robert H.",
""
],
[
"Kieburg",
"Mario",
""
]
] | A black hole evaporates by Hawking radiation. Each mode of that radiation is thermal. If the total state is nevertheless to be pure, modes must be entangled. Estimating the minimum size of this entanglement has been an important outstanding issue. We develop a new theory of constrained random symplectic transformations, based on that the total state is pure and Gaussian with given marginals. In the random constrained symplectic model we then compute the distribution of mode-mode correlations, from which we bound mode-mode entanglement. Modes of frequency much larger than $\frac{k_B T_{H}(t)}{\hbar}$ are not populated at time $t$ and drop out of the analysis.Among the other modes we find that correlations and hence entanglement between relatively thinly populated modes (early-time high-frequency modes and/or late modes of any frequency) to be strongly suppressed. Relatively highly populated modes (early-time low-frequency modes) can on the other hand be strongly correlated, but a detailed analysis reveals that they are nevertheless very unlikely to be entangled. Our analysis hence establishes that restoring unitarity after a complete evaporation of a black hole does not require any significant quantum entanglement between any pair of Hawking modes. Our analysis further gives exact general expressions for the distribution of mode-mode correlations in random, pure, Gaussian states with given marginals, which may have applications beyond black hole physics. |
0901.0776 | J. Mark Heinzle | J. Mark Heinzle, Claes Uggla | Mixmaster: Fact and Belief | 34 pages, 10 figures | Class.Quant.Grav.26:075016,2009 | 10.1088/0264-9381/26/7/075016 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the dynamics towards the initial singularity of Bianchi type IX
vacuum and orthogonal perfect fluid models with a linear equation of state.
Surprisingly few facts are known about the `Mixmaster' dynamics of these
models, while at the same time most of the commonly held beliefs are rather
vague. In this paper, we use Mixmaster facts as a base to build an
infrastructure that makes it possible to sharpen the main Mixmaster beliefs. We
formulate explicit conjectures concerning (i) the past asymptotic states of
type IX solutions and (ii) the relevance of the Mixmaster/Kasner map for
generic past asymptotic dynamics. The evidence for the conjectures is based on
a study of the stochastic properties of this map in conjunction with dynamical
systems techniques. We use a dynamical systems formulation, since this approach
has so far been the only successful path to obtain theorems, but we also make
comparisons with the `metric' and Hamiltonian `billiard' approaches.
| [
{
"created": "Wed, 7 Jan 2009 13:14:26 GMT",
"version": "v1"
}
] | 2009-03-27 | [
[
"Heinzle",
"J. Mark",
""
],
[
"Uggla",
"Claes",
""
]
] | We consider the dynamics towards the initial singularity of Bianchi type IX vacuum and orthogonal perfect fluid models with a linear equation of state. Surprisingly few facts are known about the `Mixmaster' dynamics of these models, while at the same time most of the commonly held beliefs are rather vague. In this paper, we use Mixmaster facts as a base to build an infrastructure that makes it possible to sharpen the main Mixmaster beliefs. We formulate explicit conjectures concerning (i) the past asymptotic states of type IX solutions and (ii) the relevance of the Mixmaster/Kasner map for generic past asymptotic dynamics. The evidence for the conjectures is based on a study of the stochastic properties of this map in conjunction with dynamical systems techniques. We use a dynamical systems formulation, since this approach has so far been the only successful path to obtain theorems, but we also make comparisons with the `metric' and Hamiltonian `billiard' approaches. |
2105.06101 | Jo\~ao Lu\'is Rosa | Jo\~ao Lu\'is Rosa, Matheus A. Marques, Dionisio Bazeia, Francisco S.
N. Lobo | Thick branes in the scalar-tensor representation of $f(R,T)$ gravity | 14 pages, 12 figures | European Physical Journal C 81:981 (2021) | 10.1140/epjc/s10052-021-09783-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Braneworld scenarios consider our observable universe as a brane embedded in
a five-dimensional bulk. In this work, we consider thick braneworld systems in
the recently proposed dynamically equivalent scalar-tensor representation of
$f(R,T)$ gravity, where $R$ is the Ricci scalar and $T$ the trace of the
stress-energy tensor. In the general $f\left(R,T\right)$ case we consider two
different models: a brane model without matter fields where the geometry is
supported solely by the gravitational fields, and a second model where matter
is described by a scalar field with a potential. The particular cases for which
the function $f\left(R,T\right)$ is separable in the forms $F\left(R\right)+T$
and $R+G\left(T\right)$, which give rise to scalar-tensor representations with
a single auxiliary scalar field, are studied separately. The stability of the
gravitational sector is investigated and the models are shown to be stable
against small perturbations of the metric. Furthermore, we show that in the
$f\left(R,T\right)$ model in the presence of an extra matter field, the shape
of the graviton zero-mode develops internal structure under appropriate choices
of the parameters of the model.
| [
{
"created": "Thu, 13 May 2021 06:37:43 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Nov 2021 08:52:00 GMT",
"version": "v2"
}
] | 2021-11-11 | [
[
"Rosa",
"João Luís",
""
],
[
"Marques",
"Matheus A.",
""
],
[
"Bazeia",
"Dionisio",
""
],
[
"Lobo",
"Francisco S. N.",
""
]
] | Braneworld scenarios consider our observable universe as a brane embedded in a five-dimensional bulk. In this work, we consider thick braneworld systems in the recently proposed dynamically equivalent scalar-tensor representation of $f(R,T)$ gravity, where $R$ is the Ricci scalar and $T$ the trace of the stress-energy tensor. In the general $f\left(R,T\right)$ case we consider two different models: a brane model without matter fields where the geometry is supported solely by the gravitational fields, and a second model where matter is described by a scalar field with a potential. The particular cases for which the function $f\left(R,T\right)$ is separable in the forms $F\left(R\right)+T$ and $R+G\left(T\right)$, which give rise to scalar-tensor representations with a single auxiliary scalar field, are studied separately. The stability of the gravitational sector is investigated and the models are shown to be stable against small perturbations of the metric. Furthermore, we show that in the $f\left(R,T\right)$ model in the presence of an extra matter field, the shape of the graviton zero-mode develops internal structure under appropriate choices of the parameters of the model. |
0803.0574 | Yun Soo Myung | Yong-Wan Kim, Hyung Won Lee, Yun Soo Myung, Mu-In Park | New agegraphic dark energy model with generalized uncertainty principle | 9 pages, 1 figure, version to appear in MPLA | Mod.Phys.Lett.A23:3049-3055,2008 | 10.1142/S021773230802848X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the new agegraphic dark energy models with generalized
uncertainty principle (GUP). It turns out that although the GUP affects the
early universe, it does not change the current and future dark energy-dominated
universe significantly. Furthermore, this model could describe the
matter-dominated universe in the past only when the parameter $n$ is chosen to
be $n>n_c$, where the critical value determined to be $n_c=2.799531478$.
| [
{
"created": "Wed, 5 Mar 2008 00:53:04 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Aug 2008 23:12:38 GMT",
"version": "v2"
}
] | 2008-12-25 | [
[
"Kim",
"Yong-Wan",
""
],
[
"Lee",
"Hyung Won",
""
],
[
"Myung",
"Yun Soo",
""
],
[
"Park",
"Mu-In",
""
]
] | We investigate the new agegraphic dark energy models with generalized uncertainty principle (GUP). It turns out that although the GUP affects the early universe, it does not change the current and future dark energy-dominated universe significantly. Furthermore, this model could describe the matter-dominated universe in the past only when the parameter $n$ is chosen to be $n>n_c$, where the critical value determined to be $n_c=2.799531478$. |
2101.07917 | Jos\'e Villanueva | Mart\'in Molina and J.R. Villanueva | On the thermodynamics of the Hayward black hole | Accepted for publication in Class. Quantum Grav | null | 10.1088/1361-6382/abdd47 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In light of the growing interest in the Hayward black hole solution, a
detailed study on the corresponding lapse function and its roots is presented.
The lapse function is expressed in terms of the classical Schwarzschild radius
$r_s$ and the Hayward's parameter $l$. Both of these quantities are used as
thermodynamic variables to find related thermodynamic quantities. In this
context, the variable $l$ is associated with a canonical conjugate variable
$\mathcal{F}_H$, and a free energy $\Xi$. Moreover, a second order phase
transition is found to appears at $l\approx0.333\,r_s$.
| [
{
"created": "Wed, 20 Jan 2021 01:05:33 GMT",
"version": "v1"
}
] | 2021-06-09 | [
[
"Molina",
"Martín",
""
],
[
"Villanueva",
"J. R.",
""
]
] | In light of the growing interest in the Hayward black hole solution, a detailed study on the corresponding lapse function and its roots is presented. The lapse function is expressed in terms of the classical Schwarzschild radius $r_s$ and the Hayward's parameter $l$. Both of these quantities are used as thermodynamic variables to find related thermodynamic quantities. In this context, the variable $l$ is associated with a canonical conjugate variable $\mathcal{F}_H$, and a free energy $\Xi$. Moreover, a second order phase transition is found to appears at $l\approx0.333\,r_s$. |
2006.06713 | Bhramar Chatterjee Dr. | Bhramar Chatterjee and Narayan Banerjee | Estimation of temperature of cosmological apparent horizons: a new
approach | 11 pages, A few references added | null | 10.1140/epjc/s10052-021-09408-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider radiation from cosmological apparent horizon in
Friedmann-Lemaitre-Robertson-Walker(FLRW) model in a double-null coordinate
setting. As the spacetime is dynamic, there is no timelike Killing vector,
instead we have Kodama vector which acts as dynamical time. We construct the
positive frequency modes of the Kodama vector across the horizon. The
conditional probability that a signal reaches the central observer when it is
crossing from the outside gives the temperature associated with the horizon.
| [
{
"created": "Thu, 11 Jun 2020 18:12:47 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Jun 2020 10:10:16 GMT",
"version": "v2"
}
] | 2021-07-28 | [
[
"Chatterjee",
"Bhramar",
""
],
[
"Banerjee",
"Narayan",
""
]
] | We consider radiation from cosmological apparent horizon in Friedmann-Lemaitre-Robertson-Walker(FLRW) model in a double-null coordinate setting. As the spacetime is dynamic, there is no timelike Killing vector, instead we have Kodama vector which acts as dynamical time. We construct the positive frequency modes of the Kodama vector across the horizon. The conditional probability that a signal reaches the central observer when it is crossing from the outside gives the temperature associated with the horizon. |
0810.1929 | Anil Zenginoglu C | Anil Zenginoglu, Dario Nunez, Sascha Husa | Gravitational perturbations of Schwarzschild spacetime at null infinity
and the hyperboloidal initial value problem | 14 pages, 9 figures | Class.Quant.Grav.26:035009,2009 | 10.1088/0264-9381/26/3/035009 | AEI-2008-081 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study gravitational perturbations of Schwarzschild spacetime by solving a
hyperboloidal initial value problem for the Bardeen-Press equation.
Compactification along hyperboloidal surfaces in a scri-fixing gauge allows us
to have access to the gravitational waveform at null infinity in a general
setup. We argue that this hyperboloidal approach leads to a more accurate and
efficient calculation of the radiation signal than the common approach where a
timelike outer boundary is introduced. The method can be generalized to study
perturbations of Kerr spacetime using the Teukolsky equation.
| [
{
"created": "Fri, 10 Oct 2008 17:55:30 GMT",
"version": "v1"
}
] | 2009-01-16 | [
[
"Zenginoglu",
"Anil",
""
],
[
"Nunez",
"Dario",
""
],
[
"Husa",
"Sascha",
""
]
] | We study gravitational perturbations of Schwarzschild spacetime by solving a hyperboloidal initial value problem for the Bardeen-Press equation. Compactification along hyperboloidal surfaces in a scri-fixing gauge allows us to have access to the gravitational waveform at null infinity in a general setup. We argue that this hyperboloidal approach leads to a more accurate and efficient calculation of the radiation signal than the common approach where a timelike outer boundary is introduced. The method can be generalized to study perturbations of Kerr spacetime using the Teukolsky equation. |
0704.2986 | Heiner Olbermann | Heiner Olbermann | States of Low Energy on Robertson-Walker Spacetimes | 24 pages, minor changes, acknoledgements added | Class.Quant.Grav.24:5011-5030,2007 | 10.1088/0264-9381/24/20/007 | null | gr-qc | null | We construct a new class of physical states of the free Klein-Gordon field in
Robertson-Walker spacetimes. This is done by minimizing the expectation value
of smeared stress-energy. We get an explicit expression for the state depending
on the smearing function. We call it a state of low energy. States of low
energy are an improvement of the concept of adiabatic vacua on Robertson-Walker
spacetimes. The latter are approximations of the former. It is shown that
states of low energy are Hadamard states.
| [
{
"created": "Mon, 23 Apr 2007 14:53:42 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Apr 2007 14:01:09 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Olbermann",
"Heiner",
""
]
] | We construct a new class of physical states of the free Klein-Gordon field in Robertson-Walker spacetimes. This is done by minimizing the expectation value of smeared stress-energy. We get an explicit expression for the state depending on the smearing function. We call it a state of low energy. States of low energy are an improvement of the concept of adiabatic vacua on Robertson-Walker spacetimes. The latter are approximations of the former. It is shown that states of low energy are Hadamard states. |
2110.14496 | Masroor C. Pookkillath | Antonio De Felice, Shinji Mukohyama, Masroor C. Pookkillath | Static, spherically symmetric objects in Type-II minimally modified
gravity | 11 pages, no figures, uses revtex | null | 10.1103/PhysRevD.105.104013 | YITP-21-127, IPMU21-0068 | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Static, spherically symmetric solutions representing stars made of barotropic
perfect fluid are studied in the context of two theories of type-II minimally
modified gravity, VCDM and VCCDM. Both of these theories share the property
that no additional degree of freedom is introduced in the gravity sector, and
propagate only two gravitational waves besides matter fields, as in General
Relativity (GR). We find that, on imposing physical boundary conditions on the
Misner-Sharp mass of the system, the solutions in V(C)CDM exactly coincide with
the ones in GR, namely they also satisfy the Tolman-Oppenheimer-Volkoff
equation.
| [
{
"created": "Wed, 27 Oct 2021 15:11:33 GMT",
"version": "v1"
}
] | 2022-05-25 | [
[
"De Felice",
"Antonio",
""
],
[
"Mukohyama",
"Shinji",
""
],
[
"Pookkillath",
"Masroor C.",
""
]
] | Static, spherically symmetric solutions representing stars made of barotropic perfect fluid are studied in the context of two theories of type-II minimally modified gravity, VCDM and VCCDM. Both of these theories share the property that no additional degree of freedom is introduced in the gravity sector, and propagate only two gravitational waves besides matter fields, as in General Relativity (GR). We find that, on imposing physical boundary conditions on the Misner-Sharp mass of the system, the solutions in V(C)CDM exactly coincide with the ones in GR, namely they also satisfy the Tolman-Oppenheimer-Volkoff equation. |
1406.4098 | James Bardeen | James M. Bardeen | Black hole evaporation without an event horizon | null | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A reformulation of the calculation of the semi-classical energy-momentum
tensor on a Schwarzschild background, the Bousso covariant entropy bound, and
the ER=EPR conjecture of Maldacena and Susskind taken together suggest a
scenario for the evaporation of a large spherically symmetric black hole formed
in gravitational collapse in which 1) the classical r = 0 singularity is
replaced by an initially small non-singular core inside an inner apparent
horizon, 2) the radius of the core grows with time due to the increasing
entanglement between Hawking radiation quanta outside the black hole and the
Hawking partner quanta in the core contributing to the quantum back-reaction,
and 3) by the Page time the trapped surfaces disappear and all quantum
information stored in the interior is free to escape. The scenario preserves
unitarity without any need for a "firewall" in the vicinity of the outer
apparent horizon. Qbits in the Hawking radiation are never mutually entangled,
and their number never exceeds the Bekenstein-Hawking entropy of the black
hole. The quantum back-reaction, while it must be very large in the deep
interior of the black hole, can be described semi-classically in the vicinity
of the outer apparent horizon up until close to the Page time. An explicit toy
model for the metric in the interior of the black hole, and how its associated
energy-momentum tensor can be continued to the exterior in a semi-classical
approximation, is discussed.
| [
{
"created": "Mon, 16 Jun 2014 18:51:48 GMT",
"version": "v1"
}
] | 2014-06-17 | [
[
"Bardeen",
"James M.",
""
]
] | A reformulation of the calculation of the semi-classical energy-momentum tensor on a Schwarzschild background, the Bousso covariant entropy bound, and the ER=EPR conjecture of Maldacena and Susskind taken together suggest a scenario for the evaporation of a large spherically symmetric black hole formed in gravitational collapse in which 1) the classical r = 0 singularity is replaced by an initially small non-singular core inside an inner apparent horizon, 2) the radius of the core grows with time due to the increasing entanglement between Hawking radiation quanta outside the black hole and the Hawking partner quanta in the core contributing to the quantum back-reaction, and 3) by the Page time the trapped surfaces disappear and all quantum information stored in the interior is free to escape. The scenario preserves unitarity without any need for a "firewall" in the vicinity of the outer apparent horizon. Qbits in the Hawking radiation are never mutually entangled, and their number never exceeds the Bekenstein-Hawking entropy of the black hole. The quantum back-reaction, while it must be very large in the deep interior of the black hole, can be described semi-classically in the vicinity of the outer apparent horizon up until close to the Page time. An explicit toy model for the metric in the interior of the black hole, and how its associated energy-momentum tensor can be continued to the exterior in a semi-classical approximation, is discussed. |
1311.3156 | Martin Reiris | Martin Reiris | Instability of the extreme Kerr-Newman black-holes | 25 pages. 6 figures | null | null | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using black-hole inequalities and the increase of the horizon's areas, we
show that there are arbitrarily small electro-vacuum perturbations of the
standard initial data of the extreme Reissner-Nordstrom black-hole that, (by
contradiction), cannot decay in time into any extreme Kerr-Newman black-hole.
This proves the expectation that the family of extreme Kerr-Newman black-holes
is unstable. It remains of course to be seen whether the whole family of
charged black-holes, including those extremes, is stable or not.
| [
{
"created": "Wed, 13 Nov 2013 15:03:43 GMT",
"version": "v1"
}
] | 2013-11-14 | [
[
"Reiris",
"Martin",
""
]
] | Using black-hole inequalities and the increase of the horizon's areas, we show that there are arbitrarily small electro-vacuum perturbations of the standard initial data of the extreme Reissner-Nordstrom black-hole that, (by contradiction), cannot decay in time into any extreme Kerr-Newman black-hole. This proves the expectation that the family of extreme Kerr-Newman black-holes is unstable. It remains of course to be seen whether the whole family of charged black-holes, including those extremes, is stable or not. |
gr-qc/9809019 | Ezra T. Newman | S. Frittelli, E.T. Newman, G. Silva-Ortigoza | The Eikonal Equation in Flat Space: Null Surfaces and Their
Singularities I | 33 pages, figures not included, accepted for publication in JMP | J.Math.Phys. 40 (1999) 383-407 | 10.1063/1.532777 | null | gr-qc | null | The level surfaces of solutions to the eikonal equation define null or
characteristic surfaces. In this note we study, in Minkowski space, properties
of these surfaces. In particular we are interested both in the singularities of
these ``surfaces'' (which can in general self-intersect and be only piece-wise
smooth) and in the decomposition of the null surfaces into a one parameter
family of two-dimensional wavefronts which can also have self-intersections and
singularities.
We first review a beautiful method for constructing the general solution to
the flat-space eikonal equation; it allows for solutions either from arbitrary
Cauchy data or for time independent (stationary) solutions of the form
S=t-S_{0}(x,y,z). We then apply this method to obtain global, asymptotically
spherical, null surfaces that are associated with shearing ("bad")
two-dimensional cuts of null infinity; the surfaces are defined from the normal
rays to the cut. This is followed by a study of the caustics and singularities
of these surfaces and those of their associated wavefronts. We then treat the
same set of issues from an alternative point of view, namely from Arnold's
theory of generating families. This treatment allows one to deal
(parametrically) with the regions of self-intersection and non-smoothness of
the null surfaces, regions which are difficult to treat otherwise.
Finally we generalize the analysis of the singularities to families of
solutions of the eikonal equation.
| [
{
"created": "Thu, 3 Sep 1998 18:50:39 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Frittelli",
"S.",
""
],
[
"Newman",
"E. T.",
""
],
[
"Silva-Ortigoza",
"G.",
""
]
] | The level surfaces of solutions to the eikonal equation define null or characteristic surfaces. In this note we study, in Minkowski space, properties of these surfaces. In particular we are interested both in the singularities of these ``surfaces'' (which can in general self-intersect and be only piece-wise smooth) and in the decomposition of the null surfaces into a one parameter family of two-dimensional wavefronts which can also have self-intersections and singularities. We first review a beautiful method for constructing the general solution to the flat-space eikonal equation; it allows for solutions either from arbitrary Cauchy data or for time independent (stationary) solutions of the form S=t-S_{0}(x,y,z). We then apply this method to obtain global, asymptotically spherical, null surfaces that are associated with shearing ("bad") two-dimensional cuts of null infinity; the surfaces are defined from the normal rays to the cut. This is followed by a study of the caustics and singularities of these surfaces and those of their associated wavefronts. We then treat the same set of issues from an alternative point of view, namely from Arnold's theory of generating families. This treatment allows one to deal (parametrically) with the regions of self-intersection and non-smoothness of the null surfaces, regions which are difficult to treat otherwise. Finally we generalize the analysis of the singularities to families of solutions of the eikonal equation. |
2006.13628 | M. Ghasemi-Nodehi | M. Ghasemi-Nodehi | Testing Ghasemi-Nodehi-Bambi spacetime with continuum-fitting method | Published | Eur.Phys.J.C 80 (2020) 5, 405 | 10.1140/epjc/s10052-020-7916-8 | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | The continuum-fitting method is the analysis of the thermal spectrum of the
geometrically thin and optically thick accretion disk around stellar-mass black
holes. A parametrization aiming to test the Kerr nature of astrophysical black
holes was proposed in Ghasemi-Nodehi and Bambi in EPJC 76: 290, 2016. The
metric contains 11 parameters in addition to the mass and spin parameters. One
can recover the Kerr case by setting all parameters to one. In this paper, I
study the continuum-fitting method in Ghasemi-Nodehi-Bambi background. I show
the impact of each of the parameters on the spectra. I then employ \c{hi}2
studies and show that using the continuum-fitting method all parameters of
Ghasemi-Nodehi- Bambi spacetime are degenerate. However, the parameter b9 can
be constrained in the case of a high spin value and the Ghasemi-Nodehi-Bambi
black hole as reference. This degeneracy means that the spectra of the Kerr
case cannot be distinguished from spectra produced in Ghasemi-Nodehi-Bmabi
spacetime. This is a problem as regards measuring the spin of astrophysical
black holes and constrain possible deviations from the Kerr case of General
Relativity.
| [
{
"created": "Wed, 24 Jun 2020 11:08:35 GMT",
"version": "v1"
}
] | 2020-07-01 | [
[
"Ghasemi-Nodehi",
"M.",
""
]
] | The continuum-fitting method is the analysis of the thermal spectrum of the geometrically thin and optically thick accretion disk around stellar-mass black holes. A parametrization aiming to test the Kerr nature of astrophysical black holes was proposed in Ghasemi-Nodehi and Bambi in EPJC 76: 290, 2016. The metric contains 11 parameters in addition to the mass and spin parameters. One can recover the Kerr case by setting all parameters to one. In this paper, I study the continuum-fitting method in Ghasemi-Nodehi-Bambi background. I show the impact of each of the parameters on the spectra. I then employ \c{hi}2 studies and show that using the continuum-fitting method all parameters of Ghasemi-Nodehi- Bambi spacetime are degenerate. However, the parameter b9 can be constrained in the case of a high spin value and the Ghasemi-Nodehi-Bambi black hole as reference. This degeneracy means that the spectra of the Kerr case cannot be distinguished from spectra produced in Ghasemi-Nodehi-Bmabi spacetime. This is a problem as regards measuring the spin of astrophysical black holes and constrain possible deviations from the Kerr case of General Relativity. |
gr-qc/0703094 | J. Ponce de Leon | J. Ponce de Leon | The equivalence principle in Kaluza-Klein gravity | V3: The abstract and the Introduction section are improved. V4: Two
more references added to the Conclusion section. Accepted for publication in
IJMPD | Int.J.Mod.Phys.D18:251-273,2009 | 10.1142/S0218271809014418 | null | gr-qc | null | In four-dimensional general relativity the spacetime outside of an isolated
spherical star is described by a unique line element, which is the
Schwarzschild metric. As a consequence, the "gravitational" mass and the
"inertial" mass of a star are equal to each other. However, theories that
envision our world as embedded in a larger universe, with more than four
dimensions, permit a number of possible non-Schwarzschild 4D exteriors, which
typically lead to {\it different} masses, violating the weak equivalence
principle of ordinary general relativity. Therefore, the question arises of
whether the violation of this principle, i.e., the equality of gravitational
and inertial mass, is a necessary consequence of the existence of extra
dimensions. In this paper, in the context of Kaluza-Klein gravity in 5D, we
show that the answer to this question is negative. We find a one-parameter
family of asymptotically flat non-Schwarzschild static exteriors for which the
inertial and gravitational masses are equal to each other, and equal to the
Deser-Soldate mass. This family is consistent with the Newtonian weak-field
limit as well as with the general-relativistic Schwarzschild limit. Thus, we
conclude that the existence of an extra dimension, and the corresponding
non-Schwarzschild exterior, does not necessarily require different masses.
However, to an observer in 4D, it does affect the motion of test particles in
4D, which is a consequence of the departure from the usual $(4D)$ law of
geodesic motion.
| [
{
"created": "Mon, 19 Mar 2007 02:47:19 GMT",
"version": "v1"
},
{
"created": "Sun, 25 Mar 2007 19:32:57 GMT",
"version": "v2"
},
{
"created": "Tue, 19 Feb 2008 06:12:43 GMT",
"version": "v3"
},
{
"created": "Thu, 8 May 2008 06:02:14 GMT",
"version": "v4"
}
] | 2009-04-17 | [
[
"de Leon",
"J. Ponce",
""
]
] | In four-dimensional general relativity the spacetime outside of an isolated spherical star is described by a unique line element, which is the Schwarzschild metric. As a consequence, the "gravitational" mass and the "inertial" mass of a star are equal to each other. However, theories that envision our world as embedded in a larger universe, with more than four dimensions, permit a number of possible non-Schwarzschild 4D exteriors, which typically lead to {\it different} masses, violating the weak equivalence principle of ordinary general relativity. Therefore, the question arises of whether the violation of this principle, i.e., the equality of gravitational and inertial mass, is a necessary consequence of the existence of extra dimensions. In this paper, in the context of Kaluza-Klein gravity in 5D, we show that the answer to this question is negative. We find a one-parameter family of asymptotically flat non-Schwarzschild static exteriors for which the inertial and gravitational masses are equal to each other, and equal to the Deser-Soldate mass. This family is consistent with the Newtonian weak-field limit as well as with the general-relativistic Schwarzschild limit. Thus, we conclude that the existence of an extra dimension, and the corresponding non-Schwarzschild exterior, does not necessarily require different masses. However, to an observer in 4D, it does affect the motion of test particles in 4D, which is a consequence of the departure from the usual $(4D)$ law of geodesic motion. |
2106.03914 | Leonardo Modesto | Leonardo Modesto, Ali Akil, Cosimo Bambi | Conformalons and Trans-Planckian problem | 11 pages, 4 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In any conformally invariant gravitational theory, the space of exact
solutions is greatly enlarged. The Weyl's conformal invariance can then be
spontaneously broken to spherically symmetric vacuum solutions that exclude the
spacetime region inside the black hole's event horizon from our Universe. We
baptize these solutions ''conformalons''. It turns out that for all such
spacetimes nothing can reach the Schwarzschild event horizon in a finite amount
of proper time for conformally coupled ``massive'' particles, or finite values
of the affine parameter for massless particles. Therefore, for such vacuum
solutions the event horizon is an asymptotic region of the Universe. As a
general feature, all conformalons show a gravitational blueshift instead of a
gravitational redshift at the unattainable event horizon, hence avoiding the
Trans-Planckian problem in the Hawking evaporation process. The latter happens
as usual near the event horizon, but now the annihilation process between the
matter and Hawking's negative energy particles takes place outside of the event
horizon. Indeed, in these solutions the gravitational collapse consists of
matter that falls down forever towards the horizon without ever reaching it.
According to a previous work that has been faithfully adapted to the
conformalons' scenario, the information is not lost in the whole process of
singularity-free collapse and evaporation, as evident from the Penrose diagram.
| [
{
"created": "Mon, 7 Jun 2021 18:46:49 GMT",
"version": "v1"
}
] | 2021-06-09 | [
[
"Modesto",
"Leonardo",
""
],
[
"Akil",
"Ali",
""
],
[
"Bambi",
"Cosimo",
""
]
] | In any conformally invariant gravitational theory, the space of exact solutions is greatly enlarged. The Weyl's conformal invariance can then be spontaneously broken to spherically symmetric vacuum solutions that exclude the spacetime region inside the black hole's event horizon from our Universe. We baptize these solutions ''conformalons''. It turns out that for all such spacetimes nothing can reach the Schwarzschild event horizon in a finite amount of proper time for conformally coupled ``massive'' particles, or finite values of the affine parameter for massless particles. Therefore, for such vacuum solutions the event horizon is an asymptotic region of the Universe. As a general feature, all conformalons show a gravitational blueshift instead of a gravitational redshift at the unattainable event horizon, hence avoiding the Trans-Planckian problem in the Hawking evaporation process. The latter happens as usual near the event horizon, but now the annihilation process between the matter and Hawking's negative energy particles takes place outside of the event horizon. Indeed, in these solutions the gravitational collapse consists of matter that falls down forever towards the horizon without ever reaching it. According to a previous work that has been faithfully adapted to the conformalons' scenario, the information is not lost in the whole process of singularity-free collapse and evaporation, as evident from the Penrose diagram. |
gr-qc/0002036 | Santiago Esteban Perez Bergliaffa | S. E. Perez Bergliaffa and K. E. Hibberd | Electromagnetic waves in a wormhole geometry | LaTex file, 5 pages, 2 figures, one reference added, accepted for
publication in PRD | Phys.Rev. D62 (2000) 044045 | 10.1103/PhysRevD.62.044045 | null | gr-qc astro-ph | null | We investigate the propagation of electromagnetic waves through a static
wormhole. It is shown that the problem can be reduced to a one-dimensional
Schr\"odinger-like equation with a barrier-type potential. Using numerical
methods, we calculate the transmission coefficient as a function of the energy.
We also discuss the polarization of the outgoing radiation due to this
gravitational scattering.
| [
{
"created": "Wed, 9 Feb 2000 16:52:41 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Jun 2000 21:01:18 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Bergliaffa",
"S. E. Perez",
""
],
[
"Hibberd",
"K. E.",
""
]
] | We investigate the propagation of electromagnetic waves through a static wormhole. It is shown that the problem can be reduced to a one-dimensional Schr\"odinger-like equation with a barrier-type potential. Using numerical methods, we calculate the transmission coefficient as a function of the energy. We also discuss the polarization of the outgoing radiation due to this gravitational scattering. |
gr-qc/0505118 | Pierre Noundjeu | P. Noundjeu | The Einstein-Vlasov-Maxwell(EVM) System with Spherical Symmetry | 24 pages, submitted to the Math.Proc.Camb.Phil.Soc | Class.Quant.Grav. 22 (2005) 5365-5384 | 10.1088/0264-9381/22/24/010 | null | gr-qc | null | We look for the global in time solution of the Cauchy problem corresponding
to the asymptotically flat spherically symmetric EVM system with small initial
data. Using an estimate, we also prove that if solution of the system stated
above develops a singularity at all time, then the first one has to appear at
the center of symmetry.
| [
{
"created": "Mon, 23 May 2005 15:52:34 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Noundjeu",
"P.",
""
]
] | We look for the global in time solution of the Cauchy problem corresponding to the asymptotically flat spherically symmetric EVM system with small initial data. Using an estimate, we also prove that if solution of the system stated above develops a singularity at all time, then the first one has to appear at the center of symmetry. |
gr-qc/0410050 | Yihuan Wei | Yi-Huan Wei | Late-time phantom universe in ${\bf SO(1,1)}$ dark energy model with
exponential potential | 9 pages | Mod.Phys.Lett. A20 (2005) 1147-1154 | 10.1142/S0217732305016774 | null | gr-qc | null | We discuss the late-time property of universe and phantom field in the
SO(1,1) dark energy model for the potential $V=V_0e^{-\beta\Phi^\alpha}$ with
$\alpha$ and $\beta$ two positive constants. We assume in advance some
conditions satisfied by the late-time field to simplify equations, which are
confirmed to be correct from the eventual results. For $\alpha<2$, the filed
falls exponentially off and the phantom equation of state rapidly approaches
-1. When $\alpha=2$, the kinetic energy $\rho_k$ and the coupling energy
$\rho_c$ become comparable but there is always $\rho_k<-\rho_c$ so that the
phantom property of field proceeds to hold. The analysis on the perturbation to
the late-time field $\Phi$ illustrates the square effective mass of the
perturbation field is always positive and thus the phantom is stable. The
universe considered currently may evade the future sudden singularity and will
evolve to de Sitter expansion phase.
| [
{
"created": "Tue, 12 Oct 2004 06:48:15 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Nov 2004 09:01:56 GMT",
"version": "v2"
},
{
"created": "Sun, 28 Nov 2004 02:34:43 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Wei",
"Yi-Huan",
""
]
] | We discuss the late-time property of universe and phantom field in the SO(1,1) dark energy model for the potential $V=V_0e^{-\beta\Phi^\alpha}$ with $\alpha$ and $\beta$ two positive constants. We assume in advance some conditions satisfied by the late-time field to simplify equations, which are confirmed to be correct from the eventual results. For $\alpha<2$, the filed falls exponentially off and the phantom equation of state rapidly approaches -1. When $\alpha=2$, the kinetic energy $\rho_k$ and the coupling energy $\rho_c$ become comparable but there is always $\rho_k<-\rho_c$ so that the phantom property of field proceeds to hold. The analysis on the perturbation to the late-time field $\Phi$ illustrates the square effective mass of the perturbation field is always positive and thus the phantom is stable. The universe considered currently may evade the future sudden singularity and will evolve to de Sitter expansion phase. |
1201.5337 | Manuel Rodrigues | Manuel E. Rodrigues and Zui A. A. Oporto | Thermodynamics of phantom black holes in Einstein-Maxwell-Dilaton theory | 23 pages, version accepted for publication in Physical Review D | Phys. Rev. D 85, 104022 (2012) | 10.1103/PhysRevD.85.104022 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A thermodynamic analysis of the black hole solutions coming from the
Einstein-Maxwell-Dilaton theory (EMD) in 4D is done. By consider the canonical
and grand-canonical ensemble, we apply standard method as well as a recent
method known as Geometrothermodynamics (GTD). We are particularly interested in
the characteristics of the so called phantom black hole solutions. We will
analyze the thermodynamics of these solutions, the points of phase transition
and their extremal limit. Also the thermodynamic stability is analyzed. We
obtain a mismatch of the between the results of the GTD method when compared
with the ones obtained by the specific heat, revealing a weakness of the
method, as well as possible limitations of its applicability to very
pathological thermodynamic systems. We also found that normal and phantom
solutions are locally and globally unstable, unless for certain values of the
coupled constant of the EMD action. We also shown that the
anti-Reissner-Nordstrom solution does not posses extremal limit nor phase
transition points, contrary to the Reissner-Nordstrom case.
| [
{
"created": "Wed, 25 Jan 2012 18:11:09 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Mar 2012 04:06:54 GMT",
"version": "v2"
},
{
"created": "Fri, 13 Apr 2012 20:42:59 GMT",
"version": "v3"
}
] | 2012-06-08 | [
[
"Rodrigues",
"Manuel E.",
""
],
[
"Oporto",
"Zui A. A.",
""
]
] | A thermodynamic analysis of the black hole solutions coming from the Einstein-Maxwell-Dilaton theory (EMD) in 4D is done. By consider the canonical and grand-canonical ensemble, we apply standard method as well as a recent method known as Geometrothermodynamics (GTD). We are particularly interested in the characteristics of the so called phantom black hole solutions. We will analyze the thermodynamics of these solutions, the points of phase transition and their extremal limit. Also the thermodynamic stability is analyzed. We obtain a mismatch of the between the results of the GTD method when compared with the ones obtained by the specific heat, revealing a weakness of the method, as well as possible limitations of its applicability to very pathological thermodynamic systems. We also found that normal and phantom solutions are locally and globally unstable, unless for certain values of the coupled constant of the EMD action. We also shown that the anti-Reissner-Nordstrom solution does not posses extremal limit nor phase transition points, contrary to the Reissner-Nordstrom case. |
1311.0601 | Alexey Golovnev | Alexey Golovnev, Aleksandr Klementev | On hyperbolicity violations in cosmological models with vector fields | 6 pages; minor changes, a few references added | Journal of Cosmology and Astroparticle Physics, JCAP02(2014)033 | 10.1088/1475-7516/2014/02/033 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Cosmological models with vector fields received much attention in recent
years. Unfortunately, most of them are plagued with severe instabilities or
other problems. In particular, it was noted by G. Esposito-Farese, C. Pitrou
and J.-Ph. Uzan in arXiv:0912.0481 that the models with a non-linear function
of the Maxwellian kinetic term do always imply violations of hyperbolicity
somewhere in the phase space. In this work we make this statement more precise
in several respects and show that those violations may not be present around
spatially homogeneous configurations of the vector field.
| [
{
"created": "Mon, 4 Nov 2013 08:07:51 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Dec 2013 18:22:17 GMT",
"version": "v2"
}
] | 2014-02-24 | [
[
"Golovnev",
"Alexey",
""
],
[
"Klementev",
"Aleksandr",
""
]
] | Cosmological models with vector fields received much attention in recent years. Unfortunately, most of them are plagued with severe instabilities or other problems. In particular, it was noted by G. Esposito-Farese, C. Pitrou and J.-Ph. Uzan in arXiv:0912.0481 that the models with a non-linear function of the Maxwellian kinetic term do always imply violations of hyperbolicity somewhere in the phase space. In this work we make this statement more precise in several respects and show that those violations may not be present around spatially homogeneous configurations of the vector field. |
1506.00390 | Izzet Sakalli | H. Gursel and I. Sakalli | Hawking Radiation of Massive Vector Particles From Warped AdS$_3$ Black
Hole | 5 pages. Some typos are corrected. To be appeared in Can. J. Phys | Canadian Journal of Physics, 94, 147 (2016) | 10.1139/cjp-2015-0495 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Hawking radiation (HR) of massive vector particles from a rotating Warped
Anti-de Sitter black hole in 2+1 dimensions (WAdS$_{\text{3}}$BH) is studied in
detail. The quantum tunneling approach with the Hamilton-Jacobi method (HJM) is
applied in the Proca equation (PE), and we show that the radial function yields
the tunneling rate of the outgoing particles. Comparing the result obtained
with the Boltzmann factor, we satisfactorily reproduce the Hawking temperature
(HT) of the WAdS$_{\text{3}}$BH.
| [
{
"created": "Mon, 1 Jun 2015 08:43:21 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Oct 2015 07:13:38 GMT",
"version": "v2"
},
{
"created": "Fri, 12 Feb 2016 21:57:37 GMT",
"version": "v3"
}
] | 2016-02-16 | [
[
"Gursel",
"H.",
""
],
[
"Sakalli",
"I.",
""
]
] | Hawking radiation (HR) of massive vector particles from a rotating Warped Anti-de Sitter black hole in 2+1 dimensions (WAdS$_{\text{3}}$BH) is studied in detail. The quantum tunneling approach with the Hamilton-Jacobi method (HJM) is applied in the Proca equation (PE), and we show that the radial function yields the tunneling rate of the outgoing particles. Comparing the result obtained with the Boltzmann factor, we satisfactorily reproduce the Hawking temperature (HT) of the WAdS$_{\text{3}}$BH. |
1502.00599 | Jacek Jezierski | Jacek Jezierski and Tomasz Smo{\l}ka | A geometric description of Maxwell field in a Kerr spacetime | 19 pages | Class. Quantum Grav. 33 (2016) 125035 | 10.1088/0264-9381/33/12/125035 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the Maxwell field in the exterior of a Kerr black hole. For this
system, we propose a geometric construction of generalized Klein-Gordon
equation called Fackerell-Ipser equation. Our model is based on conformal
Yano-Kiling tensor (CYK tensor). We present non-standard properties of CYK
tensors in the Kerr spacetime which are useful in electrodynamics.
| [
{
"created": "Mon, 2 Feb 2015 20:01:30 GMT",
"version": "v1"
},
{
"created": "Sat, 11 Jun 2016 16:06:25 GMT",
"version": "v2"
}
] | 2016-06-14 | [
[
"Jezierski",
"Jacek",
""
],
[
"Smołka",
"Tomasz",
""
]
] | We consider the Maxwell field in the exterior of a Kerr black hole. For this system, we propose a geometric construction of generalized Klein-Gordon equation called Fackerell-Ipser equation. Our model is based on conformal Yano-Kiling tensor (CYK tensor). We present non-standard properties of CYK tensors in the Kerr spacetime which are useful in electrodynamics. |
1507.00406 | Anuradha Gupta | Anuradha Gupta and Achamveedu Gopakumar | Post-newtonian analysis of precessing convention for spinning compact
binaries | 20 pages, 4 figures, matches published version | Class. Quantum Grav. 32 (2015) 175002 | 10.1088/0264-9381/32/17/175002 | LIGO-P1400178 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A precessing source frame, constructed using the Newtonian orbital angular
momentum ${\bf L_{\rm N}}$, can be invoked to model inspiral gravitational
waves from generic spinning compact binaries. An attractive feature of such a
precessing convention is its ability to remove all spin precession induced
modulations from the orbital phase evolution. However, this convention usually
employs a post-Newtonian (PN) accurate precessional equation, appropriate for
the PN accurate orbital angular momentum ${\bf L}$, to evolve the ${\bf L_{\rm
N}}$-based precessing source frame. This influenced us to develop inspiral
waveforms for spinning compact binaries in a precessing convention that
explicitly employ ${\bf L}$ to describe the binary orbits. Our approach
introduces certain additional 3PN order terms in the evolution equations for
the orbital phase and frequency with respect to the usual ${\bf L_{\rm
N}}$-based implementation of the precessing convention. We examine the
practical implications of these additional terms by computing the match between
inspiral waveforms that employ ${\bf L}$ and ${\bf L_{\rm N}}$-based precessing
conventions. The match estimates are found to be smaller than the optimal
value, namely $0.97$, for a non-negligible fraction of unequal mass spinning
compact binaries.
| [
{
"created": "Thu, 2 Jul 2015 01:55:25 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Aug 2015 05:54:08 GMT",
"version": "v2"
}
] | 2015-08-06 | [
[
"Gupta",
"Anuradha",
""
],
[
"Gopakumar",
"Achamveedu",
""
]
] | A precessing source frame, constructed using the Newtonian orbital angular momentum ${\bf L_{\rm N}}$, can be invoked to model inspiral gravitational waves from generic spinning compact binaries. An attractive feature of such a precessing convention is its ability to remove all spin precession induced modulations from the orbital phase evolution. However, this convention usually employs a post-Newtonian (PN) accurate precessional equation, appropriate for the PN accurate orbital angular momentum ${\bf L}$, to evolve the ${\bf L_{\rm N}}$-based precessing source frame. This influenced us to develop inspiral waveforms for spinning compact binaries in a precessing convention that explicitly employ ${\bf L}$ to describe the binary orbits. Our approach introduces certain additional 3PN order terms in the evolution equations for the orbital phase and frequency with respect to the usual ${\bf L_{\rm N}}$-based implementation of the precessing convention. We examine the practical implications of these additional terms by computing the match between inspiral waveforms that employ ${\bf L}$ and ${\bf L_{\rm N}}$-based precessing conventions. The match estimates are found to be smaller than the optimal value, namely $0.97$, for a non-negligible fraction of unequal mass spinning compact binaries. |
2101.06700 | Finnian Gray | Finnian Gray, Tsuyoshi Houri, David Kubiznak, Yukinori Yasui | Symmetry operators for the conformal wave equation in rotating black
hole spacetimes | v2: extended version which contains discussion of conformally
invariant symmetry operators | null | 10.1103/PhysRevD.104.084042 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We present covariant symmetry operators for the conformal wave equation in
the (off-shell) Kerr-NUT-AdS spacetimes. These operators, that are constructed
from the principal Killing-Yano tensor, its `symmetry descendants', and the
curvature tensor, guarantee separability of the conformal wave equation in
these spacetimes. We next discuss how these operators give rise to a full set
of conformally invariant mutually commuting operators for the conformally
rescaled spacetimes and underlie the $R$-separability of the conformal wave
equation therein. Finally, by employing the WKB approximation we derive the
associated Hamilton-Jacobi equation with a scalar curvature potential term and
show its separability in the Kerr-NUT-AdS spacetimes.
| [
{
"created": "Sun, 17 Jan 2021 16:15:58 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Apr 2021 22:01:24 GMT",
"version": "v2"
}
] | 2021-10-20 | [
[
"Gray",
"Finnian",
""
],
[
"Houri",
"Tsuyoshi",
""
],
[
"Kubiznak",
"David",
""
],
[
"Yasui",
"Yukinori",
""
]
] | We present covariant symmetry operators for the conformal wave equation in the (off-shell) Kerr-NUT-AdS spacetimes. These operators, that are constructed from the principal Killing-Yano tensor, its `symmetry descendants', and the curvature tensor, guarantee separability of the conformal wave equation in these spacetimes. We next discuss how these operators give rise to a full set of conformally invariant mutually commuting operators for the conformally rescaled spacetimes and underlie the $R$-separability of the conformal wave equation therein. Finally, by employing the WKB approximation we derive the associated Hamilton-Jacobi equation with a scalar curvature potential term and show its separability in the Kerr-NUT-AdS spacetimes. |
1804.03656 | Spyros Basilakos | S. Basilakos, A. Paliathanasis, J.D. Barrow and G. Papagiannopoulos | Cosmological singularities and analytical solutions in varying vacuum
cosmologies | 16 pages, 5 figures, accepted for publication by European Physical
Journal C (EPJC) | null | 10.1140/epjc/s10052-018-6139-8 | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the dynamical features of a large family of running vacuum
cosmologies for which $\Lambda$ evolves as a polynomial in the Hubble
parameter. Specifically, using the critical point analysis we study the
existence and the stability of singular solutions which describe de-Sitter,
radiation and matter dominated eras. We find several classes of $\Lambda(H)$
cosmologies for which new analytical solutions are given in terms of Laurent
expansions. Finally, we show that the Milne universe and the $R_{h}=ct$ model
can be seen as perturbations around a specific $\Lambda(H)$ model, but this
model is unstable.
| [
{
"created": "Tue, 10 Apr 2018 10:16:31 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Apr 2018 06:36:38 GMT",
"version": "v2"
},
{
"created": "Tue, 7 Aug 2018 12:49:33 GMT",
"version": "v3"
}
] | 2018-09-26 | [
[
"Basilakos",
"S.",
""
],
[
"Paliathanasis",
"A.",
""
],
[
"Barrow",
"J. D.",
""
],
[
"Papagiannopoulos",
"G.",
""
]
] | We investigate the dynamical features of a large family of running vacuum cosmologies for which $\Lambda$ evolves as a polynomial in the Hubble parameter. Specifically, using the critical point analysis we study the existence and the stability of singular solutions which describe de-Sitter, radiation and matter dominated eras. We find several classes of $\Lambda(H)$ cosmologies for which new analytical solutions are given in terms of Laurent expansions. Finally, we show that the Milne universe and the $R_{h}=ct$ model can be seen as perturbations around a specific $\Lambda(H)$ model, but this model is unstable. |
2309.04443 | Bence B\'ecsy | Bence B\'ecsy, Neil J. Cornish, Patrick M. Meyers, Luke Zoltan Kelley,
Gabriella Agazie, Akash Anumarlapudi, Anne M. Archibald, Zaven Arzoumanian,
Paul T. Baker, Laura Blecha, Adam Brazier, Paul R. Brook, Sarah
Burke-Spolaor, J. Andrew Casey-Clyde, Maria Charisi, Shami Chatterjee,
Katerina Chatziioannou, Tyler Cohen, James M. Cordes, Fronefield Crawford, H.
Thankful Cromartie, Kathryn Crowter, Megan E. DeCesar, Paul B. Demorest,
Timothy Dolch, Elizabeth C. Ferrara, William Fiore, Emmanuel Fonseca, Gabriel
E. Freedman, Nate Garver-Daniels, Peter A. Gentile, Joseph Glaser, Deborah C.
Good, Kayhan G\"ultekin, Jeffrey S. Hazboun, Sophie Hourihane, Ross J.
Jennings, Aaron D. Johnson, Megan L. Jones, Andrew R. Kaiser, David L.
Kaplan, Matthew Kerr, Joey S. Key, Nima Laal, Michael T. Lam, William G.
Lamb, T. Joseph W. Lazio, Natalia Lewandowska, Tyson B. Littenberg, Tingting
Liu, Duncan R. Lorimer, Jing Luo, Ryan S. Lynch, Chung-Pei Ma, Dustin R.
Madison, Alexander McEwen, James W. McKee, Maura A. McLaughlin, Natasha
McMann, Bradley W. Meyers, Chiara M. F. Mingarelli, Andrea Mitridate, Cherry
Ng, David J. Nice, Stella Koch Ocker, Ken D. Olum, Timothy T. Pennucci,
Benetge B. P. Perera, Nihan S. Pol, Henri A. Radovan, Scott M. Ransom, Paul
S. Ray, Joseph D. Romano, Shashwat C. Sardesai, Ann Schmiedekamp, Carl
Schmiedekamp, Kai Schmitz, Brent J. Shapiro-Albert, Xavier Siemens, Joseph
Simon, Magdalena S. Siwek, Sophia V. Sosa Fiscella, Ingrid H. Stairs, Daniel
R. Stinebring, Kevin Stovall, Abhimanyu Susobhanan, Joseph K. Swiggum,
Stephen R. Taylor, Jacob E. Turner, Caner Unal, Michele Vallisneri, Rutger
van Haasteren, Sarah J. Vigeland, Haley M. Wahl, Caitlin A. Witt, Olivia
Young | How to Detect an Astrophysical Nanohertz Gravitational-Wave Background | 14 pages, 8 figures, version matching published paper | ApJ 959 9 (2023) | 10.3847/1538-4357/ad09e4 | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | Analysis of pulsar timing data have provided evidence for a stochastic
gravitational wave background in the nHz frequency band. The most plausible
source of such a background is the superposition of signals from millions of
supermassive black hole binaries. The standard statistical techniques used to
search for such a background and assess its significance make several
simplifying assumptions, namely: i) Gaussianity; ii) isotropy; and most often
iii) a power-law spectrum. However, a stochastic background from a finite
collection of binaries does not exactly satisfy any of these assumptions. To
understand the effect of these assumptions, we test standard analysis
techniques on a large collection of realistic simulated datasets. The dataset
length, observing schedule, and noise levels were chosen to emulate the
NANOGrav 15-year dataset. Simulated signals from millions of binaries drawn
from models based on the Illustris cosmological hydrodynamical simulation were
added to the data. We find that the standard statistical methods perform
remarkably well on these simulated datasets, despite their fundamental
assumptions not being strictly met. They are able to achieve a confident
detection of the background. However, even for a fixed set of astrophysical
parameters, different realizations of the universe result in a large variance
in the significance and recovered parameters of the background. We also find
that the presence of loud individual binaries can bias the spectral recovery of
the background if we do not account for them.
| [
{
"created": "Fri, 8 Sep 2023 17:08:52 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Dec 2023 19:50:22 GMT",
"version": "v2"
}
] | 2023-12-05 | [
[
"Bécsy",
"Bence",
""
],
[
"Cornish",
"Neil J.",
""
],
[
"Meyers",
"Patrick M.",
""
],
[
"Kelley",
"Luke Zoltan",
""
],
[
"Agazie",
"Gabriella",
""
],
[
"Anumarlapudi",
"Akash",
""
],
[
"Archibald",
"Anne M.",
... | Analysis of pulsar timing data have provided evidence for a stochastic gravitational wave background in the nHz frequency band. The most plausible source of such a background is the superposition of signals from millions of supermassive black hole binaries. The standard statistical techniques used to search for such a background and assess its significance make several simplifying assumptions, namely: i) Gaussianity; ii) isotropy; and most often iii) a power-law spectrum. However, a stochastic background from a finite collection of binaries does not exactly satisfy any of these assumptions. To understand the effect of these assumptions, we test standard analysis techniques on a large collection of realistic simulated datasets. The dataset length, observing schedule, and noise levels were chosen to emulate the NANOGrav 15-year dataset. Simulated signals from millions of binaries drawn from models based on the Illustris cosmological hydrodynamical simulation were added to the data. We find that the standard statistical methods perform remarkably well on these simulated datasets, despite their fundamental assumptions not being strictly met. They are able to achieve a confident detection of the background. However, even for a fixed set of astrophysical parameters, different realizations of the universe result in a large variance in the significance and recovered parameters of the background. We also find that the presence of loud individual binaries can bias the spectral recovery of the background if we do not account for them. |
gr-qc/0411147 | Francois Limousin | Francois Limousin (LUTH), Dorota Gondek-Rosinska (LUTH, CAMK), Eric
Gourgoulhon (LUTH) | Quasiequilibrium sequences of binary strange quark stars in general
relativity | 4 pages, 2 PostScript figures, to appear in the Proceedings of the
SF2A 04, Paris, France | null | null | null | gr-qc | null | Inspiraling compact binaries are expected to be the strongest sources of
gravitational waves for VIRGO, LIGO and other laser interferometers. We present
the first computations of quasi-equilibrium sequences of compact binaries
containing two strange quark stars (which are currently considered as a
possible alternative to neutron stars). We study a precoalescing stage in the
conformal flatness approximation of general relativity using a multidomain
spectral method. A hydrodynamical treatment is performed under the assumption
that the flow is irrotational.
| [
{
"created": "Tue, 30 Nov 2004 16:09:44 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Limousin",
"Francois",
"",
"LUTH"
],
[
"Gondek-Rosinska",
"Dorota",
"",
"LUTH, CAMK"
],
[
"Gourgoulhon",
"Eric",
"",
"LUTH"
]
] | Inspiraling compact binaries are expected to be the strongest sources of gravitational waves for VIRGO, LIGO and other laser interferometers. We present the first computations of quasi-equilibrium sequences of compact binaries containing two strange quark stars (which are currently considered as a possible alternative to neutron stars). We study a precoalescing stage in the conformal flatness approximation of general relativity using a multidomain spectral method. A hydrodynamical treatment is performed under the assumption that the flow is irrotational. |
2105.07883 | Dr. Shikha Srivastava | Umesh Kumar Sharma and Shikha Srivastava | The cosmological behaviour and the statefinder diagnosis for the New
Tsallis agegraphic dark energy | 10 pages, 7 figures | Modern Physics Letters A Vol. 35, No. 38 (2020) 2050318 (10 pages) | 10.1142/S0217732320503186 | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | In this work, we have considered the recently proposed new Tsallis Agegraphic
Dark Energy model (NTADE) (Mod. Phys. Lett. A 34, 1950086, 2019) within the
framework of a flat Friedmann-Robertson-Walker(FRW)
Universe by taking various values of the parameter $\delta$. The NTADE model
shows the current phase transition of the Universe from
decelerated to accelerated phase. The NTADE EoS parameter shows a rich
behaviour as it can be quintessence-like or phantom-like depending on the value
of $\delta$. For discriminating the NTADE model from $\Lambda$CDM, we have
plotted the statefinder parameters $r(z)$, $s(z)$ and $(r, s)$, $(r, q)$ pair.
The NTADE model shows distinct evolutionary trajectories of their evolution in
($ r, s$) and ($ r, q$) plane. An analysis using the snap parameter and
the $\omega_{D}-\omega_{D}^{'}$ pair dynamical analysis have also been
performed.
| [
{
"created": "Fri, 14 May 2021 07:12:56 GMT",
"version": "v1"
}
] | 2021-05-18 | [
[
"Sharma",
"Umesh Kumar",
""
],
[
"Srivastava",
"Shikha",
""
]
] | In this work, we have considered the recently proposed new Tsallis Agegraphic Dark Energy model (NTADE) (Mod. Phys. Lett. A 34, 1950086, 2019) within the framework of a flat Friedmann-Robertson-Walker(FRW) Universe by taking various values of the parameter $\delta$. The NTADE model shows the current phase transition of the Universe from decelerated to accelerated phase. The NTADE EoS parameter shows a rich behaviour as it can be quintessence-like or phantom-like depending on the value of $\delta$. For discriminating the NTADE model from $\Lambda$CDM, we have plotted the statefinder parameters $r(z)$, $s(z)$ and $(r, s)$, $(r, q)$ pair. The NTADE model shows distinct evolutionary trajectories of their evolution in ($ r, s$) and ($ r, q$) plane. An analysis using the snap parameter and the $\omega_{D}-\omega_{D}^{'}$ pair dynamical analysis have also been performed. |
1511.04425 | Cupatitzio Ram\'irez Romero | C. Ram\'irez and V. V\'azquez-B\'aez | Quantum supersymmetric FRW cosmology with a scalar field | 12 pages, 11 figures | null | 10.1103/PhysRevD.93.043505 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the quantum supersymmetric cosmological FRW model with a scalar
field, with a conditional probability density and the scalar field identified
as time. The Hilbert space has a spinorial structure and there is only one
consistent solution, with a conserved probability density. The dynamics of the
scale factor is obtained from its mean value. The uncertainty relations are
fulfilled and the corresponding fluctuations are consistent with a
semiclassical Universe. We give two examples which turn out to have negative
potential.
| [
{
"created": "Fri, 13 Nov 2015 20:36:08 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Dec 2015 22:55:51 GMT",
"version": "v2"
}
] | 2016-03-23 | [
[
"Ramírez",
"C.",
""
],
[
"Vázquez-Báez",
"V.",
""
]
] | We analyze the quantum supersymmetric cosmological FRW model with a scalar field, with a conditional probability density and the scalar field identified as time. The Hilbert space has a spinorial structure and there is only one consistent solution, with a conserved probability density. The dynamics of the scale factor is obtained from its mean value. The uncertainty relations are fulfilled and the corresponding fluctuations are consistent with a semiclassical Universe. We give two examples which turn out to have negative potential. |
2111.00953 | Ke Wang | Ke Wang | Retesting the no-hair theorem with GW150914 | 5 pages, 2 figures | null | 10.1140/epjc/s10052-022-10049-x | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For a distorted black hole (BH), its ringdown waveform is a superposition of
quasi-normal modes (QNMs). In general relativity (GR), the lower order QNM
frequencies and damping rates can be well approximated by a polynomial of BH's
dimensionless spin and overall scaled by BH's mass. That is to say, we can test
the no-hair theorem of BH in GR model-independently by allowing not only an
overall fractional deviation (as M. Isi {\it et al.} did) but also a set of
fractional deviation for every coefficient. In the paper, we will apply the
latter method to retest the no-hair theorem with GW150914 and probe hairs'
behaviors if hairs exist. Eventually, we find the data favors GR.
| [
{
"created": "Mon, 1 Nov 2021 13:53:45 GMT",
"version": "v1"
},
{
"created": "Sun, 23 Jan 2022 16:45:58 GMT",
"version": "v2"
}
] | 2022-02-23 | [
[
"Wang",
"Ke",
""
]
] | For a distorted black hole (BH), its ringdown waveform is a superposition of quasi-normal modes (QNMs). In general relativity (GR), the lower order QNM frequencies and damping rates can be well approximated by a polynomial of BH's dimensionless spin and overall scaled by BH's mass. That is to say, we can test the no-hair theorem of BH in GR model-independently by allowing not only an overall fractional deviation (as M. Isi {\it et al.} did) but also a set of fractional deviation for every coefficient. In the paper, we will apply the latter method to retest the no-hair theorem with GW150914 and probe hairs' behaviors if hairs exist. Eventually, we find the data favors GR. |
1401.5104 | Sergio Mendoza | S. Mendoza, G.J. Olmo | Astrophysical constraints and insights on extended relativistic gravity | 6 pages | Astrophys.Space Sci. 357 (2015) 2, 133 | 10.1007/s10509-015-2363-y | IFIC/14-09 | gr-qc astro-ph.CO astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give precise details to support that observations of gravitational lensing
at scales of individual, groups and clusters of galaxies can be understood in
terms of non-Newtonian gravitational interactions with a relativistic structure
compatible with the Einstein Equivalence Principle. This result is derived on
very general grounds without knowing the underlying structure of the
gravitational field equations. As such, any developed gravitational theory
built to deal with these astrophysical scales needs to reproduce the obtained
results of this article.
| [
{
"created": "Mon, 20 Jan 2014 21:51:40 GMT",
"version": "v1"
}
] | 2015-06-02 | [
[
"Mendoza",
"S.",
""
],
[
"Olmo",
"G. J.",
""
]
] | We give precise details to support that observations of gravitational lensing at scales of individual, groups and clusters of galaxies can be understood in terms of non-Newtonian gravitational interactions with a relativistic structure compatible with the Einstein Equivalence Principle. This result is derived on very general grounds without knowing the underlying structure of the gravitational field equations. As such, any developed gravitational theory built to deal with these astrophysical scales needs to reproduce the obtained results of this article. |
1403.1204 | Mohammad Vahid Takook | Mohammad Vahid Takook | Quantum Field Theory in de Sitter Universe: Ambient Space Formalism | 75 pages, typos corrected, paper improved, V5 some errors corrected | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum field theory in the $4$-dimensional de Sitter space-time is
constructed in the ambient space formalism in a rigorous mathematical
framework. This work is based on the group representation theory and the
analyticity of the complexified pseudo-Riemannian manifolds. The unitary
irreducible representations of de Sitter group and their corresponding Hilbert
spaces are reformulated in the ambient space formalism. Defining the creation
and annihilation operators, quantum field operators and their corresponding
analytic two-point functions for various spin fields have been constructed. The
various spin massless fields can be constructed in terms of the massless
conformally coupled scalar field in this formalism. Then the quantum massless
minimally coupled scalar field operator, for the first time, is also
constructed on Bunch-Davies vacuum state which preserve the analyticity. We
show that the massless fields with $s \geq 3$ cannot propagate in de Sitter
ambient space formalism. The massless gauge invariant field equations for $s=1,
\frac{3}{2}, 2$ are studied. The gauge spin-$\frac{3}{2}$ fields satisfy the
Grassmannian algebra, and hence provoke one to couple them with the gauge
spin-$2$ field and the super-algebra is naturally appeared.
| [
{
"created": "Wed, 5 Mar 2014 18:06:08 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Mar 2014 04:44:02 GMT",
"version": "v2"
},
{
"created": "Wed, 3 Sep 2014 19:29:50 GMT",
"version": "v3"
},
{
"created": "Tue, 29 Dec 2015 16:36:18 GMT",
"version": "v4"
},
{
"cre... | 2016-07-21 | [
[
"Takook",
"Mohammad Vahid",
""
]
] | Quantum field theory in the $4$-dimensional de Sitter space-time is constructed in the ambient space formalism in a rigorous mathematical framework. This work is based on the group representation theory and the analyticity of the complexified pseudo-Riemannian manifolds. The unitary irreducible representations of de Sitter group and their corresponding Hilbert spaces are reformulated in the ambient space formalism. Defining the creation and annihilation operators, quantum field operators and their corresponding analytic two-point functions for various spin fields have been constructed. The various spin massless fields can be constructed in terms of the massless conformally coupled scalar field in this formalism. Then the quantum massless minimally coupled scalar field operator, for the first time, is also constructed on Bunch-Davies vacuum state which preserve the analyticity. We show that the massless fields with $s \geq 3$ cannot propagate in de Sitter ambient space formalism. The massless gauge invariant field equations for $s=1, \frac{3}{2}, 2$ are studied. The gauge spin-$\frac{3}{2}$ fields satisfy the Grassmannian algebra, and hence provoke one to couple them with the gauge spin-$2$ field and the super-algebra is naturally appeared. |
2112.11168 | Laura Sberna | Laura Sberna, Pablo Bosch, William E. East, Stephen R. Green, Luis
Lehner | Nonlinear effects in the black hole ringdown: absorption-induced mode
excitation | 15+4 pages, 9+4 figures | Phys. Rev. D 105, 064046 (2022) | 10.1103/PhysRevD.105.064046 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational-wave observations of black hole ringdowns are commonly used to
characterize binary merger remnants and to test general relativity. These
analyses assume linear black hole perturbation theory, in particular that the
ringdown can be described in terms of quasinormal modes even for times
approaching the merger. Here we investigate a nonlinear effect during the
ringdown, namely how a mode excited at early times can excite additional modes
as it is absorbed by the black hole. This is a third-order secular effect: the
change in the black-hole mass causes a shift in the mode spectrum, so that the
original mode is projected onto the new ones. Using nonlinear simulations, we
study the ringdown of a spherically-symmetric scalar field around an
asymptotically anti-de Sitter black hole, and we find that this
"absorption-induced mode excitation" (AIME) is the dominant nonlinear effect.
We show that this effect takes place well within the nonadiabatic regime, so we
can analytically estimate it using a sudden mass-change approximation. Adapting
our estimation technique to asymptotically-flat Schwarzschild black holes, we
expect AIME to play a role in the analysis and interpretation of current and
future gravitational wave observations.
| [
{
"created": "Tue, 21 Dec 2021 13:04:18 GMT",
"version": "v1"
}
] | 2022-08-31 | [
[
"Sberna",
"Laura",
""
],
[
"Bosch",
"Pablo",
""
],
[
"East",
"William E.",
""
],
[
"Green",
"Stephen R.",
""
],
[
"Lehner",
"Luis",
""
]
] | Gravitational-wave observations of black hole ringdowns are commonly used to characterize binary merger remnants and to test general relativity. These analyses assume linear black hole perturbation theory, in particular that the ringdown can be described in terms of quasinormal modes even for times approaching the merger. Here we investigate a nonlinear effect during the ringdown, namely how a mode excited at early times can excite additional modes as it is absorbed by the black hole. This is a third-order secular effect: the change in the black-hole mass causes a shift in the mode spectrum, so that the original mode is projected onto the new ones. Using nonlinear simulations, we study the ringdown of a spherically-symmetric scalar field around an asymptotically anti-de Sitter black hole, and we find that this "absorption-induced mode excitation" (AIME) is the dominant nonlinear effect. We show that this effect takes place well within the nonadiabatic regime, so we can analytically estimate it using a sudden mass-change approximation. Adapting our estimation technique to asymptotically-flat Schwarzschild black holes, we expect AIME to play a role in the analysis and interpretation of current and future gravitational wave observations. |
gr-qc/0308077 | Shijun Yoshida | Shijun Yoshida, Toshifumi Futamase | Numerical analysis of quasinormal modes in nearly extremal
Schwarzschild-de Sitter spacetimes | 9 pages, 7 figures, to appear in Physical Review D | Phys.Rev. D69 (2004) 064025 | 10.1103/PhysRevD.69.064025 | null | gr-qc | null | We calculate high-order quasinormal modes with large imaginary frequencies
for electromagnetic and gravitational perturbations in nearly extremal
Schwarzschild-de Sitter spacetimes. Our results show that for low-order
quasinormal modes, the analytical approximation formula in the extremal limit
derived by Cardoso and Lemos is a quite good approximation for the quasinormal
frequencies as long as the model parameter $r_1\kappa_1$ is small enough, where
$r_1$ and $\kappa_1$ are the black hole horizon radius and the surface gravity,
respectively. For high-order quasinormal modes, to which corresponds
quasinormal frequencies with large imaginary parts, on the other hand, this
formula becomes inaccurate even for small values of $r_1\kappa_1$. We also find
that the real parts of the quasinormal frequencies have oscillating behaviors
in the limit of highly damped modes, which are similar to those observed in the
case of a Reissner-Nordstr{\" o}m black hole. The amplitude of oscillating
${\rm Re(\omega)}$ as a function of ${\rm Im}(\omega)$ approaches a non-zero
constant value for gravitational perturbations and zero for electromagnetic
perturbations in the limit of highly damped modes, where $\omega$ denotes the
quasinormal frequency. This means that for gravitational perturbations, the
real part of quasinormal modes of the nearly extremal Schwarzschild-de Sitter
spacetime appears not to approach any constant value in the limit of highly
damped modes. On the other hand, for electromagnetic perturbations, the real
part of frequency seems to go to zero in the limit.
| [
{
"created": "Sun, 24 Aug 2003 11:14:33 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Sep 2003 14:59:56 GMT",
"version": "v2"
},
{
"created": "Thu, 20 Nov 2003 11:02:39 GMT",
"version": "v3"
},
{
"created": "Thu, 22 Jan 2004 10:34:51 GMT",
"version": "v4"
}
] | 2009-11-10 | [
[
"Yoshida",
"Shijun",
""
],
[
"Futamase",
"Toshifumi",
""
]
] | We calculate high-order quasinormal modes with large imaginary frequencies for electromagnetic and gravitational perturbations in nearly extremal Schwarzschild-de Sitter spacetimes. Our results show that for low-order quasinormal modes, the analytical approximation formula in the extremal limit derived by Cardoso and Lemos is a quite good approximation for the quasinormal frequencies as long as the model parameter $r_1\kappa_1$ is small enough, where $r_1$ and $\kappa_1$ are the black hole horizon radius and the surface gravity, respectively. For high-order quasinormal modes, to which corresponds quasinormal frequencies with large imaginary parts, on the other hand, this formula becomes inaccurate even for small values of $r_1\kappa_1$. We also find that the real parts of the quasinormal frequencies have oscillating behaviors in the limit of highly damped modes, which are similar to those observed in the case of a Reissner-Nordstr{\" o}m black hole. The amplitude of oscillating ${\rm Re(\omega)}$ as a function of ${\rm Im}(\omega)$ approaches a non-zero constant value for gravitational perturbations and zero for electromagnetic perturbations in the limit of highly damped modes, where $\omega$ denotes the quasinormal frequency. This means that for gravitational perturbations, the real part of quasinormal modes of the nearly extremal Schwarzschild-de Sitter spacetime appears not to approach any constant value in the limit of highly damped modes. On the other hand, for electromagnetic perturbations, the real part of frequency seems to go to zero in the limit. |
1506.08561 | Shinji Tsujikawa | Shinji Tsujikawa | Cosmological disformal transformations to the Einstein frame and
gravitational couplings with matter perturbations | 22 pages, 4 figures | Phys. Rev. D 92, 064047 (2015) | 10.1103/PhysRevD.92.064047 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The disformal transformation of metric $g_{\mu \nu} \to \Omega^2 (\phi)g_{\mu
\nu}+\Gamma(\phi,X) \partial_{\mu}\phi \partial_{\nu}\phi$, where $\phi$ is a
scalar field with the kinetic energy $X= \partial_{\mu}\phi
\partial^{\mu}\phi/2$, preserves the Lagrangian structure of
Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories (which is the minimum
extension of Horndeski theories). In the presence of matter, this
transformation gives rise to a kinetic-type coupling between the scalar field
$\phi$ and matter. We consider the Einstein frame in which the second-order
action of tensor perturbations on the isotropic cosmological background is of
the same form as that in General Relativity and study the role of couplings at
the levels of both background and linear perturbations. We show that the
effective gravitational potential felt by matter perturbations in the Einstein
frame can be conveniently expressed in terms of the sum of a General
Relativistic contribution and couplings induced by the modification of gravity.
For the theories in which the transformed action belongs to a class of
Horndeski theories, there is no anisotropic stress between two gravitational
potentials in the Einstein frame due to a gravitational de-mixing. We propose a
concrete dark energy model encompassing Brans-Dicke theories as well as
theories with the tensor propagation speed $c_{\rm t}$ different from 1. We
clarify the correspondence between physical quantities in the Jordan/Einstein
frames and study the evolution of gravitational potentials and matter
perturbations from the matter-dominated epoch to today in both analytic and
numerical approaches.
| [
{
"created": "Mon, 29 Jun 2015 09:40:03 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Oct 2015 06:25:22 GMT",
"version": "v2"
}
] | 2015-10-07 | [
[
"Tsujikawa",
"Shinji",
""
]
] | The disformal transformation of metric $g_{\mu \nu} \to \Omega^2 (\phi)g_{\mu \nu}+\Gamma(\phi,X) \partial_{\mu}\phi \partial_{\nu}\phi$, where $\phi$ is a scalar field with the kinetic energy $X= \partial_{\mu}\phi \partial^{\mu}\phi/2$, preserves the Lagrangian structure of Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories (which is the minimum extension of Horndeski theories). In the presence of matter, this transformation gives rise to a kinetic-type coupling between the scalar field $\phi$ and matter. We consider the Einstein frame in which the second-order action of tensor perturbations on the isotropic cosmological background is of the same form as that in General Relativity and study the role of couplings at the levels of both background and linear perturbations. We show that the effective gravitational potential felt by matter perturbations in the Einstein frame can be conveniently expressed in terms of the sum of a General Relativistic contribution and couplings induced by the modification of gravity. For the theories in which the transformed action belongs to a class of Horndeski theories, there is no anisotropic stress between two gravitational potentials in the Einstein frame due to a gravitational de-mixing. We propose a concrete dark energy model encompassing Brans-Dicke theories as well as theories with the tensor propagation speed $c_{\rm t}$ different from 1. We clarify the correspondence between physical quantities in the Jordan/Einstein frames and study the evolution of gravitational potentials and matter perturbations from the matter-dominated epoch to today in both analytic and numerical approaches. |
1606.06994 | Saheb Soroushfar | Sara Dastan, Reza Saffari, Saheb Soroushfar | Shadow of a Charged Rotating Black Hole in $f(R)$ Gravity | 28 pages,6 tables,43 figures | Eur. Phys. J. Plus 137, 1002 (2022) | 10.1140/epjp/s13360-022-03218-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the shadow of a charged rotating black hole in $f(R)$ gravity. This
black hole is characterized by mass, $M$, spin, $a$, electric charge, $Q$ and
$R_{0}$ which is proportional to cosmological constant. We analyze the image of
the black hole's shadow in four types 1) at $r\rightarrow\infty$, 2) at
$r\rightarrow r_{o}$, in vacuum, 3) at $r\rightarrow\infty$, 4) at
$r\rightarrow r_{o}$, for an observer at the presence of plasma. Moreover, we
investigate the effect of spin, charge and modfication of gravity on the shape
of shadow. In addition, we use two observables, the radius $R_{s}$ and the
distortion parameter $\delta_{s}$, characterizing the apparent shape. We show
that for all cases, the shadow becomes smaller with increasing electric charge.
Also, by increasing the rotation parameters, circular symmetry of the image of
black hole's shadow will change. Furthermore, in the presence of plasma, plasma
parameter also effects on size of the shadow.
| [
{
"created": "Wed, 22 Jun 2016 15:59:45 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Jan 2017 16:08:29 GMT",
"version": "v2"
}
] | 2022-10-06 | [
[
"Dastan",
"Sara",
""
],
[
"Saffari",
"Reza",
""
],
[
"Soroushfar",
"Saheb",
""
]
] | We study the shadow of a charged rotating black hole in $f(R)$ gravity. This black hole is characterized by mass, $M$, spin, $a$, electric charge, $Q$ and $R_{0}$ which is proportional to cosmological constant. We analyze the image of the black hole's shadow in four types 1) at $r\rightarrow\infty$, 2) at $r\rightarrow r_{o}$, in vacuum, 3) at $r\rightarrow\infty$, 4) at $r\rightarrow r_{o}$, for an observer at the presence of plasma. Moreover, we investigate the effect of spin, charge and modfication of gravity on the shape of shadow. In addition, we use two observables, the radius $R_{s}$ and the distortion parameter $\delta_{s}$, characterizing the apparent shape. We show that for all cases, the shadow becomes smaller with increasing electric charge. Also, by increasing the rotation parameters, circular symmetry of the image of black hole's shadow will change. Furthermore, in the presence of plasma, plasma parameter also effects on size of the shadow. |
2207.06376 | Thomas W. Baumgarte | Thomas W. Baumgarte and David Hilditch | Shock-avoiding slicing conditions: tests and calibrations | 10 pages, 11 figures | null | 10.1103/PhysRevD.106.044014 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | While the 1+log slicing condition has been extremely successful in numerous
numerical relativity simulations, it is also known to develop "gauge-shocks" in
some examples. Alternative "shock-avoiding" slicing conditions suggested by
Alcubierre prevent these pathologies in those examples, but have not yet been
explored and tested very broadly. In this paper we compare the performance of
shock-avoiding slicing conditions with those of 1+log slicing for a number of
"text-book" problems, including black holes and relativistic stars. While, in
some simulations, the shock-avoiding slicing conditions feature some unusual
properties and lead to more "gauge-dynamics" than the 1+log slicing condition,
we find that they perform quite similarly in terms of stability and accuracy,
and hence provide a very viable alternative to 1+log slicing.
| [
{
"created": "Wed, 13 Jul 2022 17:29:44 GMT",
"version": "v1"
}
] | 2022-08-17 | [
[
"Baumgarte",
"Thomas W.",
""
],
[
"Hilditch",
"David",
""
]
] | While the 1+log slicing condition has been extremely successful in numerous numerical relativity simulations, it is also known to develop "gauge-shocks" in some examples. Alternative "shock-avoiding" slicing conditions suggested by Alcubierre prevent these pathologies in those examples, but have not yet been explored and tested very broadly. In this paper we compare the performance of shock-avoiding slicing conditions with those of 1+log slicing for a number of "text-book" problems, including black holes and relativistic stars. While, in some simulations, the shock-avoiding slicing conditions feature some unusual properties and lead to more "gauge-dynamics" than the 1+log slicing condition, we find that they perform quite similarly in terms of stability and accuracy, and hence provide a very viable alternative to 1+log slicing. |
gr-qc/0606099 | Mark Hannam | Mark Hannam, Sascha Husa, Denis Pollney, Bernd Bruegmann, Niall
O'Murchadha | Geometry and Regularity of Moving Punctures | 4 pages, 2 figures. Replaced with version that matches the one
published in PRL: one extra figure, and modified abstract and introduction | Phys.Rev.Lett.99:241102,2007 | 10.1103/PhysRevLett.99.241102 | null | gr-qc | null | Significant advances in numerical simulations of black-hole binaries have
recently been achieved using the puncture method. We examine how and why this
method works by evolving a single black hole. The coordinate singularity and
hence the geometry at the puncture are found to change during evolution, from
representing an asymptotically flat end to being a cylinder. We construct an
analytic solution for the stationary state of a black hole in spherical
symmetry that matches the numerical result and demonstrates that the evolution
is not dominated by artefacts at the puncture but indeed finds the analytical
result.
| [
{
"created": "Fri, 23 Jun 2006 13:59:49 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Jan 2008 16:36:20 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Hannam",
"Mark",
""
],
[
"Husa",
"Sascha",
""
],
[
"Pollney",
"Denis",
""
],
[
"Bruegmann",
"Bernd",
""
],
[
"O'Murchadha",
"Niall",
""
]
] | Significant advances in numerical simulations of black-hole binaries have recently been achieved using the puncture method. We examine how and why this method works by evolving a single black hole. The coordinate singularity and hence the geometry at the puncture are found to change during evolution, from representing an asymptotically flat end to being a cylinder. We construct an analytic solution for the stationary state of a black hole in spherical symmetry that matches the numerical result and demonstrates that the evolution is not dominated by artefacts at the puncture but indeed finds the analytical result. |
1401.1398 | Gianluca Mandanici | Gianluca Mandanici | A map between Galilean relativity and special relativity | 8 pages | null | null | null | gr-qc physics.class-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A map is discussed that connects, in 1+1 dimensions, Galilei's relativity to
Einstein's special relativity. By means of this map it is possible to derive
special-relativistic formulas from the corresponding Galilean ones. Beyond
being interesting on its own, this map is also significant with respect to a
recent debate on the extension of relativistic symmetries to the Planck scale
(especially in the framework of the so-called doubly special relativity). The
map in fact provides an explicit example of how can be misleading to interpret
a mathematical correspondence between two relativity schemes as an argument in
favor of their physical equivalence.
| [
{
"created": "Sat, 28 Dec 2013 23:08:11 GMT",
"version": "v1"
}
] | 2014-01-16 | [
[
"Mandanici",
"Gianluca",
""
]
] | A map is discussed that connects, in 1+1 dimensions, Galilei's relativity to Einstein's special relativity. By means of this map it is possible to derive special-relativistic formulas from the corresponding Galilean ones. Beyond being interesting on its own, this map is also significant with respect to a recent debate on the extension of relativistic symmetries to the Planck scale (especially in the framework of the so-called doubly special relativity). The map in fact provides an explicit example of how can be misleading to interpret a mathematical correspondence between two relativity schemes as an argument in favor of their physical equivalence. |
1910.01774 | M. B. Paranjape | Matthew C. Johnson, M. B. Paranjape, Antoine Savard and Natalia
Tapia-Arellano | Stable, thin wall, negative mass bubbles in de Sitter space-time | 12 pages, 9 figures, minor changes | null | 10.1007/s10714-020-02732-9 | UdeM-GPP-TH-19-274 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Negative mass makes perfect physical sense as long as the dominant energy
condition is satisfied by the corresponding energy-momentum tensor. Heretofore,
only {\it configurations} of negative mass had been found
\cite{Belletete:2013nqa,Mbarek:2014ppa}, the analysis did not address stability
or dynamics. In this paper, we analyze both of these criteria. We demonstrate
the existence of {\it stable}, static, negative mass bubbles in an
asymptotically de Sitter space-time. The bubbles are solutions of the Einstein
equations and correspond to an interior region of space-time containing a
specific mass distribution, separated by a thin wall from the exact, negative
mass Schwarzschild-de Sitter space-time in the exterior. We apply the Israel
junction conditions at the wall. For the case of an interior corresponding
simply to de Sitter space-time with a different cosmological constant from the
outside space-time, separated by a thin wall with energy density that is
independent of the radius, we find static but unstable solutions which satisfy
the dominant energy condition everywhere. The bubbles can collapse through
spherically symmetric configurations to the exact, singular, negative mass
Schwarzschild-de Sitter solution. Interestingly, this provides a
counter-example of the cosmic censorship hypothesis. Alternatively, the
junction conditions can be used to give rise to an interior mass distribution
that depends on the potential for the radius of the wall. We show that for no
choice of the potential, for positive energy density on the wall that is
independent of the radius, can we get a solution that is non-singular at the
origin. However, if we allow the energy density on the wall to depend on the
radius of the bubble, we can find {\it stable}, static, non-singular solutions
of negative mass which everywhere satisfy the dominant energy condition.
| [
{
"created": "Fri, 4 Oct 2019 01:34:38 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Nov 2019 17:22:15 GMT",
"version": "v2"
},
{
"created": "Sat, 16 Nov 2019 22:46:23 GMT",
"version": "v3"
},
{
"created": "Sun, 17 May 2020 20:12:30 GMT",
"version": "v4"
}
] | 2020-09-09 | [
[
"Johnson",
"Matthew C.",
""
],
[
"Paranjape",
"M. B.",
""
],
[
"Savard",
"Antoine",
""
],
[
"Tapia-Arellano",
"Natalia",
""
]
] | Negative mass makes perfect physical sense as long as the dominant energy condition is satisfied by the corresponding energy-momentum tensor. Heretofore, only {\it configurations} of negative mass had been found \cite{Belletete:2013nqa,Mbarek:2014ppa}, the analysis did not address stability or dynamics. In this paper, we analyze both of these criteria. We demonstrate the existence of {\it stable}, static, negative mass bubbles in an asymptotically de Sitter space-time. The bubbles are solutions of the Einstein equations and correspond to an interior region of space-time containing a specific mass distribution, separated by a thin wall from the exact, negative mass Schwarzschild-de Sitter space-time in the exterior. We apply the Israel junction conditions at the wall. For the case of an interior corresponding simply to de Sitter space-time with a different cosmological constant from the outside space-time, separated by a thin wall with energy density that is independent of the radius, we find static but unstable solutions which satisfy the dominant energy condition everywhere. The bubbles can collapse through spherically symmetric configurations to the exact, singular, negative mass Schwarzschild-de Sitter solution. Interestingly, this provides a counter-example of the cosmic censorship hypothesis. Alternatively, the junction conditions can be used to give rise to an interior mass distribution that depends on the potential for the radius of the wall. We show that for no choice of the potential, for positive energy density on the wall that is independent of the radius, can we get a solution that is non-singular at the origin. However, if we allow the energy density on the wall to depend on the radius of the bubble, we can find {\it stable}, static, non-singular solutions of negative mass which everywhere satisfy the dominant energy condition. |
1801.06037 | Paul Klinger | Piotr T. Chru\'sciel, Paul Klinger | The annoying null boundaries | 15 pages | null | 10.1088/1742-6596/968/1/012003 | UWThPh-2017-36 | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a class of globally hyperbolic space-times with "expanding
singularities". Under suitable assumptions we show that no $C^0$-extensions
across a compact boundary exist, while the boundary must be null wherever
differentiable (which is almost everywhere) in the non-compact case.
| [
{
"created": "Thu, 18 Jan 2018 14:33:18 GMT",
"version": "v1"
}
] | 2018-03-14 | [
[
"Chruściel",
"Piotr T.",
""
],
[
"Klinger",
"Paul",
""
]
] | We consider a class of globally hyperbolic space-times with "expanding singularities". Under suitable assumptions we show that no $C^0$-extensions across a compact boundary exist, while the boundary must be null wherever differentiable (which is almost everywhere) in the non-compact case. |
1307.5470 | Bahram Mashhoon | Bahram Mashhoon and Yuri N. Obukhov | Spin Precession in Inertial and Gravitational Fields | 21 pages; v2: slightly expanded version accepted for publication in
Phys. Rev. D | Phys. Rev. D 88 (2013) 064037 | 10.1103/PhysRevD.88.064037 | null | gr-qc cond-mat.mes-hall hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the motion of spin in inertial and gravitational fields. The
coupling of spin with rotation and the gravitomagnetic field has already been
extensively studied; therefore, we focus here on the inertial and gravitational
spin-orbit couplings. In particular, we investigate the classical and quantum
aspects of spin precession and spin-orbit coupling in an arbitrary
translationally accelerated frame of reference as well as the exterior
Schwarzschild spacetime. Moreover, in connection with Einstein's principle of
equivalence, we clarify the relation between the inertial and gravitational
spin-orbit couplings.
| [
{
"created": "Sat, 20 Jul 2013 22:25:17 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Sep 2013 23:02:26 GMT",
"version": "v2"
}
] | 2013-09-25 | [
[
"Mashhoon",
"Bahram",
""
],
[
"Obukhov",
"Yuri N.",
""
]
] | We discuss the motion of spin in inertial and gravitational fields. The coupling of spin with rotation and the gravitomagnetic field has already been extensively studied; therefore, we focus here on the inertial and gravitational spin-orbit couplings. In particular, we investigate the classical and quantum aspects of spin precession and spin-orbit coupling in an arbitrary translationally accelerated frame of reference as well as the exterior Schwarzschild spacetime. Moreover, in connection with Einstein's principle of equivalence, we clarify the relation between the inertial and gravitational spin-orbit couplings. |
2310.00714 | Manuel Rodrigues | J\'ulio C. Fabris, Ednaldo L. B. Junior, Manuel E. Rodrigues | Generalized models for black-bounce solutions in $f(R)$ Gravity | 9 pages, 4 figures | Eur. Phys. J. C 83, 884 (2023) | 10.1140/epjc/s10052-023-12022-8 | null | gr-qc astro-ph.GA hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, the implementation of black-bounce solutions in $f(R)$
theories is investigated. Black-bounce solutions are regular configurations of
the static spherically symmetric space-time, containing both black holes and
wormholes structures. In General Relativity (GR), black-bounce solution implies
violation of the energy conditions. We investigate the same issue in $f(R)$
theories using two strategies: first, supposing a given form for the $f(R)$
function and then determining the matter behavior; second, imposing a condition
on the matter density and obtaining the resulting $f(R)$ function. In all
cases, a given structure for the metric functions is supposed. Violation of the
energy conditions still occur but they are less severe than in the
corresponding GR cases. We propose a zero-density model that has horizons,
which differs from the GR case. We also propose a model with positive energy
density and show that $\rho+p_r>0$, which was not the case in GR.
| [
{
"created": "Sun, 1 Oct 2023 16:23:27 GMT",
"version": "v1"
}
] | 2023-10-03 | [
[
"Fabris",
"Júlio C.",
""
],
[
"Junior",
"Ednaldo L. B.",
""
],
[
"Rodrigues",
"Manuel E.",
""
]
] | In this article, the implementation of black-bounce solutions in $f(R)$ theories is investigated. Black-bounce solutions are regular configurations of the static spherically symmetric space-time, containing both black holes and wormholes structures. In General Relativity (GR), black-bounce solution implies violation of the energy conditions. We investigate the same issue in $f(R)$ theories using two strategies: first, supposing a given form for the $f(R)$ function and then determining the matter behavior; second, imposing a condition on the matter density and obtaining the resulting $f(R)$ function. In all cases, a given structure for the metric functions is supposed. Violation of the energy conditions still occur but they are less severe than in the corresponding GR cases. We propose a zero-density model that has horizons, which differs from the GR case. We also propose a model with positive energy density and show that $\rho+p_r>0$, which was not the case in GR. |
gr-qc/0212108 | Dr. Anirudh Pradhan | Anirudh Pradhan and Abha Rai | Tilted Bianchi Type I Cosmological Models Filled with Disordered
Radiation in General Relativity Revisited | 12 pages | Astrophys.Space Sci. 286 (2003) 555-566 | 10.1023/A:1026301915781 | null | gr-qc | null | Tilted Bianchi type I cosmological models filled with disordered radiation in
presence of a bulk viscous fluid and heat flow are investigated. The
coefficient of bulk viscosity is assumed to be a power function of mass
density. Some physical and geometric properties of the models are also
discussed.
| [
{
"created": "Thu, 26 Dec 2002 16:51:38 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Pradhan",
"Anirudh",
""
],
[
"Rai",
"Abha",
""
]
] | Tilted Bianchi type I cosmological models filled with disordered radiation in presence of a bulk viscous fluid and heat flow are investigated. The coefficient of bulk viscosity is assumed to be a power function of mass density. Some physical and geometric properties of the models are also discussed. |
gr-qc/0204064 | Jean-Paul Mbelek | J.P. Mbelek (Service d'Astrophysique, CEA, Saclay, France), M.
Lachi\`eze-Rey (Service d'Astrophysique, CEA, Saclay, France) | Possible evidence from laboratory measurements for a latitude and
longitude dependence of G | Latex, 20 pages with 2 Postscript figures | Grav.Cosmol. 8 (2002) 331-338 | null | null | gr-qc | null | Stability arguments suggest that the Kaluza-Klein (KK) internal scalar field,
$\Phi$, should be coupled to some external fields. An external bulk real scalar
field, $\psi$, minimally coupled to gravity is proved to be satisfactory. At
low temperature, the coupling of $\psi$ to the electromagnetic (EM) field
allows $\Phi$ to be much stronger coupled to the EM field than in the genuine
five dimensional KK theory. It is shown that the coupling of $\Phi$ to the
geomagnetic field may explain the observed dispersion in laboratory
measurements of the (effective) gravitational constant. The analysis takes into
account the spatial variations of the geomagnetic field. Except the high PTB
value, the predictions are found in good agreement with all of the experimental
data.
| [
{
"created": "Fri, 19 Apr 2002 16:51:18 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Mbelek",
"J. P.",
"",
"Service d'Astrophysique, CEA, Saclay, France"
],
[
"Lachièze-Rey",
"M.",
"",
"Service d'Astrophysique, CEA, Saclay, France"
]
] | Stability arguments suggest that the Kaluza-Klein (KK) internal scalar field, $\Phi$, should be coupled to some external fields. An external bulk real scalar field, $\psi$, minimally coupled to gravity is proved to be satisfactory. At low temperature, the coupling of $\psi$ to the electromagnetic (EM) field allows $\Phi$ to be much stronger coupled to the EM field than in the genuine five dimensional KK theory. It is shown that the coupling of $\Phi$ to the geomagnetic field may explain the observed dispersion in laboratory measurements of the (effective) gravitational constant. The analysis takes into account the spatial variations of the geomagnetic field. Except the high PTB value, the predictions are found in good agreement with all of the experimental data. |
2310.18399 | Alexandre M. Pombo | Lorenzo Pizzuti and Alexandre M. Pombo | The spooky ghost of vectorization | 12 pages | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An interesting mechanism for the formation of hairy black holes occurs when a
vector field, non-minimally coupled to a source term, grows from a perturbation
of the vacuum black hole, \textit{aka} vectorization. Its study has, however,
been lacking, in part due to the constant threat of ghost instabilities that
have plagued vector fields. In this work, we show evidence that, in a generic
family of extended-vector-tensor theories where the vector field is
non-minimally coupled to the model's invariant (source term), a spherically
symmetric, vectorized black hole always suffers from ghost instabilities. These
ultimately turn the process of vectorization astrophysically unviable.
| [
{
"created": "Fri, 27 Oct 2023 18:00:04 GMT",
"version": "v1"
}
] | 2023-10-31 | [
[
"Pizzuti",
"Lorenzo",
""
],
[
"Pombo",
"Alexandre M.",
""
]
] | An interesting mechanism for the formation of hairy black holes occurs when a vector field, non-minimally coupled to a source term, grows from a perturbation of the vacuum black hole, \textit{aka} vectorization. Its study has, however, been lacking, in part due to the constant threat of ghost instabilities that have plagued vector fields. In this work, we show evidence that, in a generic family of extended-vector-tensor theories where the vector field is non-minimally coupled to the model's invariant (source term), a spherically symmetric, vectorized black hole always suffers from ghost instabilities. These ultimately turn the process of vectorization astrophysically unviable. |
2110.01063 | Irene Denisova | V.I.Denisov, I.P.Denisova and E.T. Einiev | The investigation of low frequency dilaton generation | 7 pages | null | 10.1140/epjc/s10052-022-10193-4 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The electromagnetic source of dilaton is a first invariant
of the electromagnetic field tensor. For
electromagnetic waves, this invariant can be non zero only in the near zone.
Pulsars and magnetars are natural sources of this type.
We calculated the generation of dilatons by coherent
electromagnetic field of rotating magnetic dipole moment
of pulsars and magnetars. It is shown that the radiation of dilaton waves
occurs at the two frequencies: the rotation frequency of the magnetic dipole
moment of the neutron star and the twice frequency.
The generation of dilaton at the rotation frequency is maximal in the case
when the angle between the magnetic dipole moment and the axis of its rotation
is equal to 45 degree. If this angle is equal to 90 degree, then dilaton
radiation at the rotation frequency does not occur. The generation of dilaton
at the twice frequency is maximal in the case when the angle between the
magnetic dipole and the axis of its rotation is equal to 90 degree.
Angular distribution of radiation of dilatons having a rotation frequency has
a maximum along conic surfaces 45 degree. Angular distribution of radiation of
dilatons having a frequency of the twice rotation frequency, has a maximum in
the plane which is perpendicular to the axis of rotation.
| [
{
"created": "Sun, 3 Oct 2021 18:24:04 GMT",
"version": "v1"
}
] | 2022-04-27 | [
[
"Denisov",
"V. I.",
""
],
[
"Denisova",
"I. P.",
""
],
[
"Einiev",
"E. T.",
""
]
] | The electromagnetic source of dilaton is a first invariant of the electromagnetic field tensor. For electromagnetic waves, this invariant can be non zero only in the near zone. Pulsars and magnetars are natural sources of this type. We calculated the generation of dilatons by coherent electromagnetic field of rotating magnetic dipole moment of pulsars and magnetars. It is shown that the radiation of dilaton waves occurs at the two frequencies: the rotation frequency of the magnetic dipole moment of the neutron star and the twice frequency. The generation of dilaton at the rotation frequency is maximal in the case when the angle between the magnetic dipole moment and the axis of its rotation is equal to 45 degree. If this angle is equal to 90 degree, then dilaton radiation at the rotation frequency does not occur. The generation of dilaton at the twice frequency is maximal in the case when the angle between the magnetic dipole and the axis of its rotation is equal to 90 degree. Angular distribution of radiation of dilatons having a rotation frequency has a maximum along conic surfaces 45 degree. Angular distribution of radiation of dilatons having a frequency of the twice rotation frequency, has a maximum in the plane which is perpendicular to the axis of rotation. |
2403.16721 | Iarley P. Lobo Dr | Giovanni Amelino-Camelia, Iarley P. Lobo and Giovanni Palmisano | Anti-de Sitter Momentum Space in 3D and 4D Quantum Gravity | 19 pages. Matches published version in Classical and Quantum Gravity,
"Special Issue: Focus on Quantum Gravity Phenomenology in the Multi-Messenger
Era: Challenges and Perspectives" | Class. Quant. Grav. 41 (2024) 8, 085006 | 10.1088/1361-6382/ad3163 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | There has been strong interest in the possibility that in the quantum-gravity
realm momentum space might be curved, mainly focusing, especially for what
concerns phenomenological implications, on the case of a de Sitter momentum
space. We here take as starting point the known fact that quantum gravity
coupled to matter in $2+1$ spacetime dimensions gives rise to an effective
picture characterized by a momentum space with anti-de Sitter geometry, and we
point out some key properties of $2+1$-dimensional anti-de Sitter momentum
space. We observe that it is impossible to implement all of these properties in
theories with a $3+1$-dimensional anti-de Sitter momentum space, and we then
investigate, with the aim of providing guidance to the relevant phenomenology
focusing on possible modified laws of conservation of momenta, the implications
of giving up, in the $3+1$-dimensional case, some of the properties of the
$2+1$-dimensional case.
| [
{
"created": "Mon, 25 Mar 2024 12:57:16 GMT",
"version": "v1"
}
] | 2024-03-26 | [
[
"Amelino-Camelia",
"Giovanni",
""
],
[
"Lobo",
"Iarley P.",
""
],
[
"Palmisano",
"Giovanni",
""
]
] | There has been strong interest in the possibility that in the quantum-gravity realm momentum space might be curved, mainly focusing, especially for what concerns phenomenological implications, on the case of a de Sitter momentum space. We here take as starting point the known fact that quantum gravity coupled to matter in $2+1$ spacetime dimensions gives rise to an effective picture characterized by a momentum space with anti-de Sitter geometry, and we point out some key properties of $2+1$-dimensional anti-de Sitter momentum space. We observe that it is impossible to implement all of these properties in theories with a $3+1$-dimensional anti-de Sitter momentum space, and we then investigate, with the aim of providing guidance to the relevant phenomenology focusing on possible modified laws of conservation of momenta, the implications of giving up, in the $3+1$-dimensional case, some of the properties of the $2+1$-dimensional case. |
2308.03342 | Merab Gogberashvili Prof | Merab Gogberashvili and Ani Girgvliani | General spherically symmetric solution of Cotton gravity | Journal version | Class. Quantum Grav. 41 (2024) 025010 | 10.1088/1361-6382/ad1781 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we present the general spherically symmetric static solution to
the vacuum equations of Cotton gravity. The obtained metric solution reveals
the presence of singularities at the photosphere of a spherical source, which
probably obstruct the formation of the stellar Schwarzschild-radius black
holes. The solution is characterized by two integration constants, whose values
can be restricted by association with the Hubble horizon. We examine the
diverse features of the solution, including the long-range modifications to
Newton's force through the incorporation of the velocity-squared repulsive term
to model the dark energy.
| [
{
"created": "Mon, 7 Aug 2023 06:50:36 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Jan 2024 06:57:57 GMT",
"version": "v2"
}
] | 2024-01-08 | [
[
"Gogberashvili",
"Merab",
""
],
[
"Girgvliani",
"Ani",
""
]
] | In this paper we present the general spherically symmetric static solution to the vacuum equations of Cotton gravity. The obtained metric solution reveals the presence of singularities at the photosphere of a spherical source, which probably obstruct the formation of the stellar Schwarzschild-radius black holes. The solution is characterized by two integration constants, whose values can be restricted by association with the Hubble horizon. We examine the diverse features of the solution, including the long-range modifications to Newton's force through the incorporation of the velocity-squared repulsive term to model the dark energy. |
gr-qc/9711031 | Jerzy Lewandowski | Abhay Ashtekar and Jerzy Lewandowski | Quantum Theory of Geometry II: Volume operators | Latex, 3 figures | Adv.Theor.Math.Phys. 1 (1998) 388-429 | null | null | gr-qc hep-th | null | A functional calculus on the space of (generalized) connections was recently
introduced without any reference to a background metric. It is used to continue
the exploration of the quantum Riemannian geometry. Operators corresponding to
volume of three-dimensional regions are regularized rigorously. It is shown
that there are two natural regularization schemes, each of which leads to a
well-defined operator. Both operators can be completely specified by giving
their action on states labelled by graphs. The two final results are closely
related but differ from one another in that one of the operators is sensitive
to the differential structure of graphs at their vertices while the second is
sensitive only to the topological characteristics. (The second operator was
first introduced by Rovelli and Smolin and De Pietri and Rovelli using a
somewhat different framework.) The difference between the two operators can be
attributed directly to the standard quantization ambiguity. Underlying
assumptions and subtleties of regularization procedures are discussed in detail
in both cases because volume operators play an important role in the current
discussions of quantum dynamics.
| [
{
"created": "Mon, 10 Nov 1997 17:21:11 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Ashtekar",
"Abhay",
""
],
[
"Lewandowski",
"Jerzy",
""
]
] | A functional calculus on the space of (generalized) connections was recently introduced without any reference to a background metric. It is used to continue the exploration of the quantum Riemannian geometry. Operators corresponding to volume of three-dimensional regions are regularized rigorously. It is shown that there are two natural regularization schemes, each of which leads to a well-defined operator. Both operators can be completely specified by giving their action on states labelled by graphs. The two final results are closely related but differ from one another in that one of the operators is sensitive to the differential structure of graphs at their vertices while the second is sensitive only to the topological characteristics. (The second operator was first introduced by Rovelli and Smolin and De Pietri and Rovelli using a somewhat different framework.) The difference between the two operators can be attributed directly to the standard quantization ambiguity. Underlying assumptions and subtleties of regularization procedures are discussed in detail in both cases because volume operators play an important role in the current discussions of quantum dynamics. |
gr-qc/0212118 | Simon DeDeo | Simon DeDeo and J. Richard Gott III | An Eternal Time Machine in 2+1 Dimensional anti-de Sitter Space | 7 pages, 4 figures. Published in Physical Review D | Phys.Rev.D66:084020,2002; Erratum-ibid.D67:069902,2003 | 10.1103/PhysRevD.66.084020 10.1103/PhysRevD.67.069902 | null | gr-qc | null | 2+1 dimensional anti-de Sitter space has been the subject of much recent
investigation. Studies of the behaviour of point particles in this space have
given us a greater understanding of the BTZ black hole solutions produced by
topological identification of adS isometries. In this paper, we present a new
configuration of two orbiting massive point particles that leads to an
``eternal'' time machine, where closed timelike curves fill the entire space.
In contrast to previous solutions, this configuration has no event or
chronology horizons. Another interesting feature is that there is no lower
bound on the relative velocities of the point masses used to construct the time
machine; as long as the particles exceed a certain mass threshold, an eternal
time machine will be produced.
| [
{
"created": "Sat, 28 Dec 2002 20:16:26 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"DeDeo",
"Simon",
""
],
[
"Gott",
"J. Richard",
"III"
]
] | 2+1 dimensional anti-de Sitter space has been the subject of much recent investigation. Studies of the behaviour of point particles in this space have given us a greater understanding of the BTZ black hole solutions produced by topological identification of adS isometries. In this paper, we present a new configuration of two orbiting massive point particles that leads to an ``eternal'' time machine, where closed timelike curves fill the entire space. In contrast to previous solutions, this configuration has no event or chronology horizons. Another interesting feature is that there is no lower bound on the relative velocities of the point masses used to construct the time machine; as long as the particles exceed a certain mass threshold, an eternal time machine will be produced. |
0711.1150 | Yuuiti Sendouda | Nathalie Deruelle, Misao Sasaki, Yuuiti Sendouda | Junction Conditions in f(R) Theories of Gravity | 18 pages | Prog.Theor.Phys.119:237-251,2008 | 10.1143/PTP.119.237 | YITP-07-76 | gr-qc astro-ph hep-th | null | Taking advantage of the conformal equivalence of f(R) theories of gravity
with General Relativity coupled to a scalar field we generalize the Israel
junction conditions for this class of theories by direct integration of the
field equations. We suggest a specific non-minimal coupling of matter to
gravity which opens the possibility of a new class of braneworld scenarios.
| [
{
"created": "Wed, 7 Nov 2007 20:22:33 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Deruelle",
"Nathalie",
""
],
[
"Sasaki",
"Misao",
""
],
[
"Sendouda",
"Yuuiti",
""
]
] | Taking advantage of the conformal equivalence of f(R) theories of gravity with General Relativity coupled to a scalar field we generalize the Israel junction conditions for this class of theories by direct integration of the field equations. We suggest a specific non-minimal coupling of matter to gravity which opens the possibility of a new class of braneworld scenarios. |
gr-qc/0703021 | Morgan Le Delliou | Morgan Le Delliou (CFTC) | Probing Dynamical Dark Energy with Press-Schechter Mass Functions | submitted to the Proceedings of the 11th Marcel Grossmann Meeting,
MG11, Berlin, Germany, July 23-29, 2006 (2007) to be published | null | 10.1142/9789812834300_0262 | null | gr-qc astro-ph hep-th | null | Measurement of accelerated expansion in the Universe led to propose a new
cosmic fluid as its cause: dark energy. Its various incarnations offer a wealth
of models whose relevance it is important to discriminate via contacts with
observations. I will present my investigations on the influence of dynamical
dark energy models on the formation of non-linear dark matter structures. In
particular, I will focus on structures traced by the mass function of dark
matter haloes.
| [
{
"created": "Sun, 4 Mar 2007 07:58:58 GMT",
"version": "v1"
}
] | 2016-11-15 | [
[
"Delliou",
"Morgan Le",
"",
"CFTC"
]
] | Measurement of accelerated expansion in the Universe led to propose a new cosmic fluid as its cause: dark energy. Its various incarnations offer a wealth of models whose relevance it is important to discriminate via contacts with observations. I will present my investigations on the influence of dynamical dark energy models on the formation of non-linear dark matter structures. In particular, I will focus on structures traced by the mass function of dark matter haloes. |
1106.0549 | Wenbiao Liu | Xiao-Xiong Zeng, Shi-Wei Zhou, Wen-Biao Liu | Landauer transport model for Hawking radiation from a Reissner-Nordstrom
black hole | null | null | 10.1088/1674-1056/21/9/090402 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The recent work of Nation et al in which Hawking radiation energy and entropy
flow from a black hole can be regarded as a one-dimensional (1D) Landauer
transport process is extended to the case of a Reissner-Nordstrom (RN) black
hole. It is found that the flow of charge current can also be transported via a
1D quantum channel except the current of Hawking radiation. The maximum entropy
current, which is shown to be particle statistics independence, is also
obtained.
| [
{
"created": "Fri, 3 Jun 2011 01:46:03 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Zeng",
"Xiao-Xiong",
""
],
[
"Zhou",
"Shi-Wei",
""
],
[
"Liu",
"Wen-Biao",
""
]
] | The recent work of Nation et al in which Hawking radiation energy and entropy flow from a black hole can be regarded as a one-dimensional (1D) Landauer transport process is extended to the case of a Reissner-Nordstrom (RN) black hole. It is found that the flow of charge current can also be transported via a 1D quantum channel except the current of Hawking radiation. The maximum entropy current, which is shown to be particle statistics independence, is also obtained. |
0903.1668 | Paolo Bonifacio | Paolo M. Bonifacio, Charles H.-T. Wang, J. Tito Mendonca, Robert
Bingham | Dephasing of a non-relativistic quantum particle due to a conformally
fluctuating spacetime | 30 pages, 4 figures; to appear in Class. Quantum Grav. (2009) | Class.Quant.Grav.26:145013,2009 | 10.1088/0264-9381/26/14/145013 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the dephasing suffered by a nonrelativistic quantum particle
within a conformally fluctuating spacetime geometry. Starting from a minimally
coupled massive Klein-Gordon field, the low velocity limit yields an effective
Schrodinger equation where the wave function couples to gravity through an
effective nonlinear potential induced by the conformal fluctuations. The
quantum evolution is studied through a Dyson expansion scheme up to second
order. We show that only the nonlinear part of the potential can induce
dephasing. This happens through an exponential decay of the off diagonal terms
of the particle density matrix. The bath of conformal radiation is modeled in
3-dimensions and its statistical properties are described in general in terms
of a power spectral density. The case of a Lorentz invariant spectral density,
allowing to model vacuum fluctuations at a low energy domain, is investigated
and a general formula describing the loss of coherence derived. This depends
quadratically on the particle mass and on the inverse cube of a typical
particle dependent cutoff scale. Finally, the possibilities for experimental
verification are discussed. It is shown that current interferometry experiments
cannot detect such an effect. However this conclusion may improve by using high
mass entangled quantum states.
| [
{
"created": "Tue, 10 Mar 2009 01:19:20 GMT",
"version": "v1"
}
] | 2009-07-24 | [
[
"Bonifacio",
"Paolo M.",
""
],
[
"Wang",
"Charles H. -T.",
""
],
[
"Mendonca",
"J. Tito",
""
],
[
"Bingham",
"Robert",
""
]
] | We investigate the dephasing suffered by a nonrelativistic quantum particle within a conformally fluctuating spacetime geometry. Starting from a minimally coupled massive Klein-Gordon field, the low velocity limit yields an effective Schrodinger equation where the wave function couples to gravity through an effective nonlinear potential induced by the conformal fluctuations. The quantum evolution is studied through a Dyson expansion scheme up to second order. We show that only the nonlinear part of the potential can induce dephasing. This happens through an exponential decay of the off diagonal terms of the particle density matrix. The bath of conformal radiation is modeled in 3-dimensions and its statistical properties are described in general in terms of a power spectral density. The case of a Lorentz invariant spectral density, allowing to model vacuum fluctuations at a low energy domain, is investigated and a general formula describing the loss of coherence derived. This depends quadratically on the particle mass and on the inverse cube of a typical particle dependent cutoff scale. Finally, the possibilities for experimental verification are discussed. It is shown that current interferometry experiments cannot detect such an effect. However this conclusion may improve by using high mass entangled quantum states. |
1211.3688 | Lorenzo Iorio | Lorenzo Iorio | Constraints on a MOND effect for isolated aspherical systems in deep
Newtonian regime from orbital motions | LaTex, 23 pages, 1 figure, 1 table, 58 references. Matching the
version at press in Classical and Quantum Gravity (CQG) | Class. Quant. Gravit..30:165018,2013 | 10.1088/0264-9381/30/16/165018 | null | gr-qc astro-ph.EP physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Non-spherical systems described by MOND theories of modified gravity arising
from generalizations of the Poisson equations are affected by a MONDian
extra-quadrupolar potential \phi_M even if they are isolated and they are in
deep Newtonian regime. In general MOND theories quickly approaching Newtonian
dynamics for accelerations beyond A_0, \phi_M is proportional to a
multiplicative scaling coefficient \alpha \sim 1, while in MOND models becoming
Newtonian beyond \kappa A_0, \kappa >> 1, it is enhanced by \kappa^2. We
analytically work out some orbital effects due to \phi_M in the framework of
QUMOND, and compare them with the latest observational determinations of Solar
System's planetary dynamics, exoplanets and double lined spectroscopic binary
stars. The current admissible range for the anomalous perihelion precession of
Saturn yields |\kappa| <= 3.5 x 10^3, while the radial velocity of \alpha Cen
AB allows to infer |\kappa|<= 6.2 x 10^4 (A) and |\kappa|<= 4.2 x 10^4 (B). In
evaluating such preliminary constraints it must be recalled that QUMOND is not
the nonrelativistic limit of TeVeS.
| [
{
"created": "Wed, 7 Nov 2012 16:18:05 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Mar 2013 16:11:13 GMT",
"version": "v2"
},
{
"created": "Thu, 7 Mar 2013 14:09:49 GMT",
"version": "v3"
},
{
"created": "Wed, 3 Jul 2013 17:15:04 GMT",
"version": "v4"
},
{
"creat... | 2013-07-30 | [
[
"Iorio",
"Lorenzo",
""
]
] | Non-spherical systems described by MOND theories of modified gravity arising from generalizations of the Poisson equations are affected by a MONDian extra-quadrupolar potential \phi_M even if they are isolated and they are in deep Newtonian regime. In general MOND theories quickly approaching Newtonian dynamics for accelerations beyond A_0, \phi_M is proportional to a multiplicative scaling coefficient \alpha \sim 1, while in MOND models becoming Newtonian beyond \kappa A_0, \kappa >> 1, it is enhanced by \kappa^2. We analytically work out some orbital effects due to \phi_M in the framework of QUMOND, and compare them with the latest observational determinations of Solar System's planetary dynamics, exoplanets and double lined spectroscopic binary stars. The current admissible range for the anomalous perihelion precession of Saturn yields |\kappa| <= 3.5 x 10^3, while the radial velocity of \alpha Cen AB allows to infer |\kappa|<= 6.2 x 10^4 (A) and |\kappa|<= 4.2 x 10^4 (B). In evaluating such preliminary constraints it must be recalled that QUMOND is not the nonrelativistic limit of TeVeS. |
1910.05663 | Adam Lewis | Adam G. M. Lewis | Hadamard Renormalization of a 2-Dimensional Dirac Field | 8 pages. A few corrections made, and a new operator is now
renormalized | Phys. Rev. D 101, 125019 (2020) | 10.1103/PhysRevD.101.125019 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Hadamard renormalization procedure is applied to a free, massive Dirac
field $\psi$ on a 2 dimensional Lorentzian spacetime. This yields the
state-independent divergent terms in the Hadamard bispinor $G^{(1)}(x, x') =
\frac{1}{2} \left\langle \left[ \bar{\psi}(x'), \psi(x) \right] \right\rangle$
as $x$ and $x'$ are brought together along the unique geodesic connecting them.
Subtracting these divergent terms within the limit assigns $G^{(1)}(x, x')$,
and thus any operator expressed in terms of it, a finite value at the
coincident point $x' = x$. In this limit, one obtains a quadratic operator
instead of a bispinor. The procedure is thus used to assign finite values to
various quadratic operators, including the stress-energy tensor. Results are
presented covariantly, in a conformally-flat coordinate chart at purely spatial
separations, and in the Minkowski metric. These terms can be directly
subtracted from combinations of $G^{(1)}(x, x')$ - themselves obtained, for
example, from a numerical simulation - to obtain finite expectation values
defined in the continuum.
| [
{
"created": "Sun, 13 Oct 2019 00:34:07 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Oct 2019 18:16:37 GMT",
"version": "v2"
},
{
"created": "Sat, 7 Mar 2020 21:33:32 GMT",
"version": "v3"
}
] | 2020-07-01 | [
[
"Lewis",
"Adam G. M.",
""
]
] | The Hadamard renormalization procedure is applied to a free, massive Dirac field $\psi$ on a 2 dimensional Lorentzian spacetime. This yields the state-independent divergent terms in the Hadamard bispinor $G^{(1)}(x, x') = \frac{1}{2} \left\langle \left[ \bar{\psi}(x'), \psi(x) \right] \right\rangle$ as $x$ and $x'$ are brought together along the unique geodesic connecting them. Subtracting these divergent terms within the limit assigns $G^{(1)}(x, x')$, and thus any operator expressed in terms of it, a finite value at the coincident point $x' = x$. In this limit, one obtains a quadratic operator instead of a bispinor. The procedure is thus used to assign finite values to various quadratic operators, including the stress-energy tensor. Results are presented covariantly, in a conformally-flat coordinate chart at purely spatial separations, and in the Minkowski metric. These terms can be directly subtracted from combinations of $G^{(1)}(x, x')$ - themselves obtained, for example, from a numerical simulation - to obtain finite expectation values defined in the continuum. |
2308.00267 | Jin Saito | Jin Saito and Tsutomu Kobayashi | Black hole perturbations in spatially covariant gravity with just two
tensorial degrees of freedom | 15pages, 4figures, | Phys. Rev. D 108, 104063 (2023) | 10.1103/PhysRevD.108.104063 | RUP-23-14 | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study linear perturbations around a static and spherically symmetric black
hole solution in spatially covariant gravity with just two tensorial degrees of
freedom. In this theory, gravity modification is characterized by a single
time-dependent function that appears in the coefficient of $K^2$ in the action,
where $K$ is the trace of the extrinsic curvature. The background black hole
solution is given by the Schwarzschild solution foliated by the maximal slices
and has a universal horizon at which the lapse function vanishes. We show that
the quadratic action for the odd-parity perturbations is identical to that in
general relativity upon performing an appropriate coordinate transformation.
This in particular implies that the odd-parity perturbations propagate at the
speed of light, with the inner boundary being the usual event horizon. We also
derive the quadratic action for even-parity perturbations. In the even-parity
sector, one of the two tensorial degrees of freedom is mixed with an
instantaneous scalar mode, rendering the system distinct from that in general
relativity. We find that monopole and dipole perturbations, which are composed
solely of the instantaneous scalar mode, have no solutions regular both at the
universal horizon and infinity (except for the trivial one corresponding to the
constant shift of the mass parameter). We also consider stationary
perturbations with higher multipoles. By carefully treating the locations of
the inner boundary, we show that also in this case there are no solutions
regular both at the inner boundary and infinity. Thus, the black hole solution
we consider is shown to be perturbatively unique.
| [
{
"created": "Tue, 1 Aug 2023 04:00:42 GMT",
"version": "v1"
}
] | 2024-02-20 | [
[
"Saito",
"Jin",
""
],
[
"Kobayashi",
"Tsutomu",
""
]
] | We study linear perturbations around a static and spherically symmetric black hole solution in spatially covariant gravity with just two tensorial degrees of freedom. In this theory, gravity modification is characterized by a single time-dependent function that appears in the coefficient of $K^2$ in the action, where $K$ is the trace of the extrinsic curvature. The background black hole solution is given by the Schwarzschild solution foliated by the maximal slices and has a universal horizon at which the lapse function vanishes. We show that the quadratic action for the odd-parity perturbations is identical to that in general relativity upon performing an appropriate coordinate transformation. This in particular implies that the odd-parity perturbations propagate at the speed of light, with the inner boundary being the usual event horizon. We also derive the quadratic action for even-parity perturbations. In the even-parity sector, one of the two tensorial degrees of freedom is mixed with an instantaneous scalar mode, rendering the system distinct from that in general relativity. We find that monopole and dipole perturbations, which are composed solely of the instantaneous scalar mode, have no solutions regular both at the universal horizon and infinity (except for the trivial one corresponding to the constant shift of the mass parameter). We also consider stationary perturbations with higher multipoles. By carefully treating the locations of the inner boundary, we show that also in this case there are no solutions regular both at the inner boundary and infinity. Thus, the black hole solution we consider is shown to be perturbatively unique. |
2103.02444 | Mir Faizal | Salman Sajad Wani, Tsou Sheung Tsun, Mir Faizal | Dualized Gravity beyond Linear Approximation | 16 pages | Eur. Phys. J. C 82, 8, 751, (2022) | 10.1140/epjc/s10052-022-10550-3 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We will construct a loop space formalism for general relativity, and
construct the Polyakov variables as connections for such a loop space. We will
use these Polyakov variables to construct a dual theory of gravity beyond
linear approximation. It will be demonstrated that this loop space duality
reduces to the Hodge duality for linearized gravity. Furthermore, a loop space
curvature will be constructed from this Polyakov variable. It will be shown
that this loop space curvature vanishes in the absence of topological defects,
and so it can be used to investigate gravitational monopoles. We will also
construct the suitable monopole charge for such gravitational monopoles.
| [
{
"created": "Tue, 2 Mar 2021 09:15:57 GMT",
"version": "v1"
}
] | 2022-09-21 | [
[
"Wani",
"Salman Sajad",
""
],
[
"Tsun",
"Tsou Sheung",
""
],
[
"Faizal",
"Mir",
""
]
] | We will construct a loop space formalism for general relativity, and construct the Polyakov variables as connections for such a loop space. We will use these Polyakov variables to construct a dual theory of gravity beyond linear approximation. It will be demonstrated that this loop space duality reduces to the Hodge duality for linearized gravity. Furthermore, a loop space curvature will be constructed from this Polyakov variable. It will be shown that this loop space curvature vanishes in the absence of topological defects, and so it can be used to investigate gravitational monopoles. We will also construct the suitable monopole charge for such gravitational monopoles. |
gr-qc/0612106 | Ying-Qiu Gu | Ying-Qiu Gu | The Vierbein Formalism and Energy-Momentum Tensor of Spinors | 14 pages, no figure | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | To study the coupling system of space-time and Fermions, we need the explicit
form of the energy-momentum tensor of spinors. The energy-momentum tensor is
closely related to the tetrad frames which cannot be uniquely determined by the
metric. This flexibility increases difficulties to derive the exact expression
and easily leads to ambiguous results. In this paper, we give a detailed
derivation for the energy-momentum tensor of Weyl and Dirac spinors. From the
results we find that, besides the usual kinetic energy momentum term, there are
three kinds of other additional terms. One is the nonlinear self-interactive
potential, which acts like negative pressure. The other reflects the
interaction of momentum $p^\mu$ with tetrad. The third is the spin-gravity
coupling term which is a higher order infinitesimal in weak field, but may be
important in a neutron star. This term is also closely related with magnetic
field of a celestial body. These results are based on the decomposition of
usual spin connection into geometrical part and dynamical part, which not only
makes calculation simpler, but also highlights their different physical
meanings. In addition, we get a new tensor $S^{\mu\nu}_{ab}$ in calculation of
tetrad formalism, which plays an important role in the interaction of spinor
with gravity.
| [
{
"created": "Mon, 18 Dec 2006 05:59:36 GMT",
"version": "v1"
},
{
"created": "Fri, 24 Apr 2009 13:10:59 GMT",
"version": "v2"
},
{
"created": "Mon, 22 May 2017 16:39:59 GMT",
"version": "v3"
},
{
"created": "Thu, 10 Aug 2017 04:43:46 GMT",
"version": "v4"
},
{
"c... | 2017-12-08 | [
[
"Gu",
"Ying-Qiu",
""
]
] | To study the coupling system of space-time and Fermions, we need the explicit form of the energy-momentum tensor of spinors. The energy-momentum tensor is closely related to the tetrad frames which cannot be uniquely determined by the metric. This flexibility increases difficulties to derive the exact expression and easily leads to ambiguous results. In this paper, we give a detailed derivation for the energy-momentum tensor of Weyl and Dirac spinors. From the results we find that, besides the usual kinetic energy momentum term, there are three kinds of other additional terms. One is the nonlinear self-interactive potential, which acts like negative pressure. The other reflects the interaction of momentum $p^\mu$ with tetrad. The third is the spin-gravity coupling term which is a higher order infinitesimal in weak field, but may be important in a neutron star. This term is also closely related with magnetic field of a celestial body. These results are based on the decomposition of usual spin connection into geometrical part and dynamical part, which not only makes calculation simpler, but also highlights their different physical meanings. In addition, we get a new tensor $S^{\mu\nu}_{ab}$ in calculation of tetrad formalism, which plays an important role in the interaction of spinor with gravity. |
gr-qc/0210036 | Jose Natario | Jose Natario and Paul Tod | Linking, Legendrian linking and causality | 30 pages, 14 figures. arXiv admin note: substantial text overlap with
arXiv:gr-qc/0108061 | Proc.Lond.Math.Soc. 88 (2004) 251-272 | null | null | gr-qc math.DG math.GT math.SG | null | The set N of all null geodesics of a globally hyperbolic (d+1)-dimensional
spacetime (M,g) is naturally a smooth (2d-1)-dimensional contact manifold. The
sky of an event is the subset of N defined by all null geodesics through that
event, and is an embedded Legendrian submanifold of N diffeomorphic to a
(d-1)-dimensional sphere. It was conjectured by Low that for d=2 two events are
causally related iff their skies are linked (in an appropriate sense). We use
the contact structure and knot polynomial calculations to prove this conjecture
in certain particular cases, and suggest that for d=3 smooth linking should be
replaced with Legendrian linking.
| [
{
"created": "Fri, 11 Oct 2002 17:14:03 GMT",
"version": "v1"
}
] | 2012-07-15 | [
[
"Natario",
"Jose",
""
],
[
"Tod",
"Paul",
""
]
] | The set N of all null geodesics of a globally hyperbolic (d+1)-dimensional spacetime (M,g) is naturally a smooth (2d-1)-dimensional contact manifold. The sky of an event is the subset of N defined by all null geodesics through that event, and is an embedded Legendrian submanifold of N diffeomorphic to a (d-1)-dimensional sphere. It was conjectured by Low that for d=2 two events are causally related iff their skies are linked (in an appropriate sense). We use the contact structure and knot polynomial calculations to prove this conjecture in certain particular cases, and suggest that for d=3 smooth linking should be replaced with Legendrian linking. |
gr-qc/0105036 | J. B. Almeida | Jose B. Almeida | On the anomalies of gravity | 8 pages, submitted to GRG. Some corrections | null | null | null | gr-qc | null | The paper is based on the recently proposed 4-dimensional optical space
theory and draws some of its consequences for gravitation. Starting with the
discussion of central movement, the paper proceeds to establish the a metric
compatible with Newtonian mechanics which can be accommodated by the new theory
and finds a correction term which can be neglected in most practical
circumstances. Being effective in the very short range, the correction term
affects substantially the results when continuous mass distributions are
considered. The main consequence is the possibility of explaining the orbital
speeds found around galaxies, without the need to appeal for a lot of dark
matter. The speed of gravity is also discussed and the theory is found
compatible with a gravitational speed equal to the speed of light. On the
subject of black holes, it is suggested that they are just a possibility but
not a geometric inevitability.
| [
{
"created": "Thu, 10 May 2001 08:25:24 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Jun 2001 13:21:34 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Almeida",
"Jose B.",
""
]
] | The paper is based on the recently proposed 4-dimensional optical space theory and draws some of its consequences for gravitation. Starting with the discussion of central movement, the paper proceeds to establish the a metric compatible with Newtonian mechanics which can be accommodated by the new theory and finds a correction term which can be neglected in most practical circumstances. Being effective in the very short range, the correction term affects substantially the results when continuous mass distributions are considered. The main consequence is the possibility of explaining the orbital speeds found around galaxies, without the need to appeal for a lot of dark matter. The speed of gravity is also discussed and the theory is found compatible with a gravitational speed equal to the speed of light. On the subject of black holes, it is suggested that they are just a possibility but not a geometric inevitability. |
gr-qc/0405113 | Hideki Maeda | Hideki Maeda and Tomohiro Harada | Kinematic self-similar solutions in general relativity | 29 pages, no figures, 1 table. This is a review for a part of the
book "Progress in General Relativity and Quantum Cosmology Research" (Nova
Science Publ.,2004) | null | null | WU-AP/185/04 | gr-qc astro-ph | null | The gravitational interaction is scale-free in both Newtonian gravity and
general theory of relativity. The concept of self-similarity arises from this
nature. Self-similar solutions reproduce themselves as the scale changes. This
property results in great simplification of the governing partial differential
equations. In addition, some self-similar solutions can describe the asymptotic
behaviors of more general solutions. Newtonian gravity contains only one
dimensional constant, the gravitational constant, while the general relativity
contains another dimensional constant, the speed of light, besides the
gravitational constant. Due to this crucial difference, incomplete similarity
can be more interesting in general relativity than in Newtonian gravity.
Kinematic self-similarity has been defined and studied as an example of
incomplete similarity in general relativity, in an effort to pursue a wider
application of self-similarity in general relativity. We review the
mathematical and physical aspects of kinematic self-similar solutions in
general relativity.
| [
{
"created": "Thu, 20 May 2004 08:38:06 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Maeda",
"Hideki",
""
],
[
"Harada",
"Tomohiro",
""
]
] | The gravitational interaction is scale-free in both Newtonian gravity and general theory of relativity. The concept of self-similarity arises from this nature. Self-similar solutions reproduce themselves as the scale changes. This property results in great simplification of the governing partial differential equations. In addition, some self-similar solutions can describe the asymptotic behaviors of more general solutions. Newtonian gravity contains only one dimensional constant, the gravitational constant, while the general relativity contains another dimensional constant, the speed of light, besides the gravitational constant. Due to this crucial difference, incomplete similarity can be more interesting in general relativity than in Newtonian gravity. Kinematic self-similarity has been defined and studied as an example of incomplete similarity in general relativity, in an effort to pursue a wider application of self-similarity in general relativity. We review the mathematical and physical aspects of kinematic self-similar solutions in general relativity. |
gr-qc/0303029 | Bahram Mashhoon | Bahram Mashhoon | The Hypothesis of Locality and its Limitations | LaTeX file, no figures, 14 pages, to appear in: "Relativity in
Rotating Frames", edited by G. Rizzi and M.L. Ruggiero (Kluwer Academic
Publishers, Dordrecht, 2003) | null | null | null | gr-qc astro-ph | null | The hypothesis of locality, its origin and consequences are discussed. This
supposition is necessary for establishing the local spacetime frame of
accelerated observers; in this connection, the measurement of length in a
rotating system is considered in detail. Various limitations of the hypothesis
of locality are examined.
| [
{
"created": "Fri, 7 Mar 2003 05:15:52 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Mashhoon",
"Bahram",
""
]
] | The hypothesis of locality, its origin and consequences are discussed. This supposition is necessary for establishing the local spacetime frame of accelerated observers; in this connection, the measurement of length in a rotating system is considered in detail. Various limitations of the hypothesis of locality are examined. |
1811.08213 | Alexander Kamenshchik | Alexander Yu. Kamenshchik, Ekaterina O. Pozdeeva, Alexei A.
Starobinsky, Alessandro Tronconi, Tereza Vardanyan, Giovanni Venturi, Sergey
Yu. Vernov | Duality between static spherically or hyperbolically symmetric solutions
and cosmological solutions in scalar-tensor gravity | The final version, published in Physical Review D, the title is
changed and some references and comments are added | Phys. Rev. D 98, 124028 (2018) | 10.1103/PhysRevD.98.124028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study static spherically and hyperbolically symmetric solutions of the
Einstein equations in the presence of a conformally coupled scalar field and
compare them with those in the space filled with a minimally coupled scalar
field. We then study the Kantowski-Sachs cosmological solutions, which are
connected with the static solutions by the duality relations. The main
ingredient of these relations is an exchange of roles between the radial and
the temporal coordinates, combined with the exchange between the spherical and
hyperbolical two-dimensional geometries. A brief discussion of questions such
as the relation between the Jordan and the Einstein frames and the description
of the singularity crossing is also presented.
| [
{
"created": "Tue, 20 Nov 2018 12:40:22 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Dec 2018 15:17:33 GMT",
"version": "v2"
}
] | 2018-12-26 | [
[
"Kamenshchik",
"Alexander Yu.",
""
],
[
"Pozdeeva",
"Ekaterina O.",
""
],
[
"Starobinsky",
"Alexei A.",
""
],
[
"Tronconi",
"Alessandro",
""
],
[
"Vardanyan",
"Tereza",
""
],
[
"Venturi",
"Giovanni",
""
],
[
"Verno... | We study static spherically and hyperbolically symmetric solutions of the Einstein equations in the presence of a conformally coupled scalar field and compare them with those in the space filled with a minimally coupled scalar field. We then study the Kantowski-Sachs cosmological solutions, which are connected with the static solutions by the duality relations. The main ingredient of these relations is an exchange of roles between the radial and the temporal coordinates, combined with the exchange between the spherical and hyperbolical two-dimensional geometries. A brief discussion of questions such as the relation between the Jordan and the Einstein frames and the description of the singularity crossing is also presented. |
2006.04360 | Nicola Maggiore | Giulio Gambuti and Nicola Maggiore | A note on Harmonic Gauge(s) in Massive Gravity | 11 pages | Physics Letters B 807 (2020) 135530 | 10.1016/j.physletb.2020.135530 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We consider the harmonic gauge condition in linearized gravity, seen as a
gauge theory for a symmetric tensor field. Once the harmonic gauge condition is
implemented, as customary, according to the Faddeev-Popov procedure, the gauge
fixed action still depends on one gauge parameter. Consequently, the harmonic
gauge appears to be a class of conditions, rather than a particular one. This
allows to give a physical motivation for the covariant harmonic gauge(s), which
emerges when the gravitational perturbation is given a mass term. In fact, for
a particular choice of harmonic gauge, we find a theory of linearized massive
gravity displaying five degrees of freedom, as it should, and which is not
affected by the vDVZ discontinuity, differently from what happens in the
standard Fierz-Pauli theory.
| [
{
"created": "Mon, 8 Jun 2020 05:22:26 GMT",
"version": "v1"
},
{
"created": "Mon, 22 Jun 2020 10:53:38 GMT",
"version": "v2"
}
] | 2020-06-23 | [
[
"Gambuti",
"Giulio",
""
],
[
"Maggiore",
"Nicola",
""
]
] | We consider the harmonic gauge condition in linearized gravity, seen as a gauge theory for a symmetric tensor field. Once the harmonic gauge condition is implemented, as customary, according to the Faddeev-Popov procedure, the gauge fixed action still depends on one gauge parameter. Consequently, the harmonic gauge appears to be a class of conditions, rather than a particular one. This allows to give a physical motivation for the covariant harmonic gauge(s), which emerges when the gravitational perturbation is given a mass term. In fact, for a particular choice of harmonic gauge, we find a theory of linearized massive gravity displaying five degrees of freedom, as it should, and which is not affected by the vDVZ discontinuity, differently from what happens in the standard Fierz-Pauli theory. |
1409.4787 | Miguel Zilh\~ao | Miguel Zilh\~ao, Scott C. Noble, Manuela Campanelli, Yosef Zlochower | Resolving the relative influence of strong field spacetime dynamics and
MHD on circumbinary disk physics | 14 pages, 12 figures. v2: matches published version in PRD | null | 10.1103/PhysRevD.91.024034 | null | gr-qc astro-ph.CO astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we evolve magnetized and unmagnetized circumbinary accretion
disks around supermassive black hole binaries in the relativistic regime. We
use a post-Newtonian expansion to construct an analytical spacetime and
determine how the order of the post-Newtonian (PN) expansion affects the
dynamics of the gas. We find very small differences in the late-time bulk
dynamics of non-magnetized hydrodynamic evolutions between the two spacetimes
down to separations of approximately $40GM/c^2$ where $M$ is the total mass of
the binary. For smaller separations, the differences due to PN-order become
comparable to differences caused by using initial data further from
equilibrium. For magnetized gas, MHD stresses, which drives the accretion
dynamics, tends to mask all higher order PN effects even at separations of
$20GM/c^2$, leading to essentially the same observed electromagnetic
luminosity. This implies that our calculations of the EM signal may be robust
down to small binary separations. Our investigation is the first to demonstrate
how the level of PN accuracy affects a circumbinary disk's evolution and
informs us of the range in separation within which to trust the PN
approximation for this kind of study. We also address the influence the initial
conditions and binary separation have on simulation predictions.
| [
{
"created": "Tue, 16 Sep 2014 20:10:08 GMT",
"version": "v1"
},
{
"created": "Sat, 31 Jan 2015 17:40:55 GMT",
"version": "v2"
}
] | 2015-02-03 | [
[
"Zilhão",
"Miguel",
""
],
[
"Noble",
"Scott C.",
""
],
[
"Campanelli",
"Manuela",
""
],
[
"Zlochower",
"Yosef",
""
]
] | In this paper we evolve magnetized and unmagnetized circumbinary accretion disks around supermassive black hole binaries in the relativistic regime. We use a post-Newtonian expansion to construct an analytical spacetime and determine how the order of the post-Newtonian (PN) expansion affects the dynamics of the gas. We find very small differences in the late-time bulk dynamics of non-magnetized hydrodynamic evolutions between the two spacetimes down to separations of approximately $40GM/c^2$ where $M$ is the total mass of the binary. For smaller separations, the differences due to PN-order become comparable to differences caused by using initial data further from equilibrium. For magnetized gas, MHD stresses, which drives the accretion dynamics, tends to mask all higher order PN effects even at separations of $20GM/c^2$, leading to essentially the same observed electromagnetic luminosity. This implies that our calculations of the EM signal may be robust down to small binary separations. Our investigation is the first to demonstrate how the level of PN accuracy affects a circumbinary disk's evolution and informs us of the range in separation within which to trust the PN approximation for this kind of study. We also address the influence the initial conditions and binary separation have on simulation predictions. |
gr-qc/9704069 | Giacomo Giampieri | G.Giampieri | On the Antenna Pattern of an Orbiting Interferometer | RevTeX, 17 pages, 11 ps figures. To appear in MNRAS | null | 10.1093/mnras/289.1.185 | QMW-AU-97006 | gr-qc | null | The response of an interferometer changing its orientation with respect to a
fixed reference frame is given in terms of the beam-pattern factors and the
polarization-averaged antenna power pattern.
| [
{
"created": "Thu, 24 Apr 1997 17:30:17 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Giampieri",
"G.",
""
]
] | The response of an interferometer changing its orientation with respect to a fixed reference frame is given in terms of the beam-pattern factors and the polarization-averaged antenna power pattern. |
0704.1224 | Alexei Zayats | Alexander B. Balakin, Sergey V. Sushkov, Alexei E. Zayats | Non-minimal Wu-Yang wormhole | 9 pages, 2 figures, typos corrected, 2 references added | Phys.Rev.D75:084042,2007 | 10.1103/PhysRevD.75.084042 | null | gr-qc astro-ph hep-ph hep-th | null | We discuss exact solutions of three-parameter non-minimal Einstein-Yang-Mills
model, which describe the wormholes of a new type. These wormholes are
considered to be supported by SU(2)-symmetric Yang-Mills field, non-minimally
coupled to gravity, the Wu-Yang ansatz for the gauge field being used. We
distinguish between regular solutions, describing traversable non-minimal
Wu-Yang wormholes, and black wormholes possessing one or two event horizons.
The relation between the asymptotic mass of the regular traversable Wu-Yang
wormhole and its throat radius is analysed.
| [
{
"created": "Tue, 10 Apr 2007 12:30:02 GMT",
"version": "v1"
},
{
"created": "Wed, 2 May 2007 11:52:42 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Balakin",
"Alexander B.",
""
],
[
"Sushkov",
"Sergey V.",
""
],
[
"Zayats",
"Alexei E.",
""
]
] | We discuss exact solutions of three-parameter non-minimal Einstein-Yang-Mills model, which describe the wormholes of a new type. These wormholes are considered to be supported by SU(2)-symmetric Yang-Mills field, non-minimally coupled to gravity, the Wu-Yang ansatz for the gauge field being used. We distinguish between regular solutions, describing traversable non-minimal Wu-Yang wormholes, and black wormholes possessing one or two event horizons. The relation between the asymptotic mass of the regular traversable Wu-Yang wormhole and its throat radius is analysed. |
1611.07531 | LVC Publications | The LIGO Scientific Collaboration and the Virgo Collaboration: B. P.
Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C.
Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M.
Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith,
B. Allen, A. Allocca, P. A. Altin, A. Ananyeva, S. B. Anderson, W. G.
Anderson, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, N. Arnaud, K. G.
Arun, S. Ascenzi, G. Ashton, M. Ast, S. M. Aston, P. Astone, P. Aufmuth, C.
Aulbert, A. Avila-Alvarez, S. Babak, P. Bacon, M. K. M. Bader, P. T. Baker,
F. Baldaccini, G. Ballardin, S. W. Ballmer, J. C. Barayoga, S. E. Barclay, B.
C. Barish, D. Barker, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, D.
Barta, J. Bartlett, I. Bartos, R. Bassiri, A. Basti, J. C. Batch, C. Baune,
V. Bavigadda, M. Bazzan, C. Beer, M. Bejger, I. Belahcene, M. Belgin, A. S.
Bell, B. K. Berger, G. Bergmann, C. P. L. Berry, D. Bersanetti, A. Bertolini,
J. Betzwieser, S. Bhagwat, R. Bhandare, I. A. Bilenko, G. Billingsley, C. R.
Billman, J. Birch, R. Birney, O. Birnholtz, S. Biscans, A. Bisht, M. Bitossi,
C. Biwer, M. A. Bizouard, J. K. Blackburn, J. Blackman, C. D. Blair, D. G.
Blair, R. M. Blair, S. Bloemen, O. Bock, M. Boer, G. Bogaert, A. Bohe, F.
Bondu, R. Bonnand, B. A. Boom, R. Bork, V. Boschi, S. Bose, Y. Bouffanais, A.
Bozzi, C. Bradaschia, P. R. Brady, V. B. Braginsky, M. Branchesi, J. E. Brau,
T. Briant, A. Brillet, M. Brinkmann, V. Brisson, P. Brockill, J. E. Broida,
A. F. Brooks, D. A. Brown, D. D. Brown, N. M. Brown, S. Brunett, C. C.
Buchanan, A. Buikema, T. Bulik, H. J. Bulten, A. Buonanno, D. Buskulic, C.
Buy, R. L. Byer, M. Cabero, L. Cadonati, G. Cagnoli, C. Cahillane, J.
Calder'on Bustillo, T. A. Callister, E. Calloni, J. B. Camp, K. C. Cannon, H.
Cao, J. Cao, C. D. Capano, E. Capocasa, F. Carbognani, S. Caride, J.
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G. Wang, H. Wang, M. Wang, Y. Wang, R. L. Ward, J. Warner, M. Was, J. Watchi,
B. Weaver, L.-W. Wei, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, P.
Wessels, T. Westphal, K. Wette, J. T. Whelan, B. F. Whiting, C. Whittle, D.
Williams, R. D. Williams, A. R. Williamson, J. L. Willis, B. Willke, M. H.
Wimmer, W. Winkler, C. C. Wipf, H. Wittel, G. Woan, J. Woehler, J. Worden, J.
L. Wright, D. S. Wu, G. Wu, W. Yam, H. Yamamoto, C. C. Yancey, M. J. Yap,
Hang Yu, Haocun Yu, M. Yvert, A. Zadro.zny, L. Zangrando, M. Zanolin, J.-P.
Zendri, M. Zevin, L. Zhang, M. Zhang, T. Zhang, Y. Zhang, C. Zhao, M. Zhou,
Z. Zhou, S. J. Zhu, X. J. Zhu, M. E. Zucker, J. Zweizig, M. Boyle, T. Chu, D.
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Teukolsky, A. Vano-Vinuales | Effects of waveform model systematics on the interpretation of GW150914 | 29 pages, 9 figures | Class. Quantum Grav. 34 (2017) 104002 | 10.1088/1361-6382/aa6854 | P1500259 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Parameter estimates of GW150914 were obtained using Bayesian inference, based
on three semi-analytic waveform models for binary black hole coalescences.
These waveform models differ from each other in their treatment of black hole
spins, and all three models make some simplifying assumptions, notably to
neglect sub-dominant waveform harmonic modes and orbital eccentricity.
Furthermore, while the models are calibrated to agree with waveforms obtained
by full numerical solutions of Einstein's equations, any such calibration is
accurate only to some non-zero tolerance and is limited by the accuracy of the
underlying phenomenology, availability, quality, and parameter-space coverage
of numerical simulations. This paper complements the original analyses of
GW150914 with an investigation of the effects of possible systematic errors in
the waveform models on estimates of its source parameters. To test for
systematic errors we repeat the original Bayesian analyses on mock signals from
numerical simulations of a series of binary configurations with parameters
similar to those found for GW150914. Overall, we find no evidence for a
systematic bias relative to the statistical error of the original parameter
recovery of GW150914 due to modeling approximations or modeling inaccuracies.
However, parameter biases are found to occur for some configurations disfavored
by the data of GW150914: for binaries inclined edge-on to the detector over a
small range of choices of polarization angles, and also for eccentricities
greater than $\sim$0.05. For signals with higher signal-to-noise ratio than
GW150914, or in other regions of the binary parameter space (lower masses,
larger mass ratios, or higher spins), we expect that systematic errors in
current waveform models may impact gravitational-wave measurements, making more
accurate models desirable for future observations.
| [
{
"created": "Tue, 22 Nov 2016 21:00:24 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Apr 2017 14:38:24 GMT",
"version": "v2"
}
] | 2017-04-19 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"Abbott",
"B. P.",
""
],
[
"Abbott",
"R.",
""
],
[
"Abbott",
"T. D.",
""
],
[
"Abernathy",
"M. R.",
""
],
[
"Acernese",
"F... | Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semi-analytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions, notably to neglect sub-dominant waveform harmonic modes and orbital eccentricity. Furthermore, while the models are calibrated to agree with waveforms obtained by full numerical solutions of Einstein's equations, any such calibration is accurate only to some non-zero tolerance and is limited by the accuracy of the underlying phenomenology, availability, quality, and parameter-space coverage of numerical simulations. This paper complements the original analyses of GW150914 with an investigation of the effects of possible systematic errors in the waveform models on estimates of its source parameters. To test for systematic errors we repeat the original Bayesian analyses on mock signals from numerical simulations of a series of binary configurations with parameters similar to those found for GW150914. Overall, we find no evidence for a systematic bias relative to the statistical error of the original parameter recovery of GW150914 due to modeling approximations or modeling inaccuracies. However, parameter biases are found to occur for some configurations disfavored by the data of GW150914: for binaries inclined edge-on to the detector over a small range of choices of polarization angles, and also for eccentricities greater than $\sim$0.05. For signals with higher signal-to-noise ratio than GW150914, or in other regions of the binary parameter space (lower masses, larger mass ratios, or higher spins), we expect that systematic errors in current waveform models may impact gravitational-wave measurements, making more accurate models desirable for future observations. |
gr-qc/0506051 | Fernando C. Lombardo | Fernando C. Lombardo and Diana Lopez Nacir | Decoherence during Inflation: the generation of classical
inhomogeneities | 17 pages, 15 figures. To appear in Phys. Rev. D | Phys.Rev. D72 (2005) 063506 | 10.1103/PhysRevD.72.063506 | null | gr-qc astro-ph hep-ph hep-th | null | We show how the quantum to classical transition of the cosmological
fluctuations produced during inflation can be described by means of the
influence functional and the master equation. We split the inflaton field into
the system-field (long-wavelength modes), and the environment, represented by
its own short-wavelength modes. We compute the decoherence times for the
system-field modes and compare them with the other time scales of the model. We
present the renormalized stochastic Langevin equation for an homogeneous
system-field and then we analyze the influence of the environment on the power
spectrum for some modes in the system.
| [
{
"created": "Wed, 8 Jun 2005 20:33:23 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Aug 2005 19:24:49 GMT",
"version": "v2"
},
{
"created": "Tue, 23 Aug 2005 16:02:26 GMT",
"version": "v3"
}
] | 2016-08-31 | [
[
"Lombardo",
"Fernando C.",
""
],
[
"Nacir",
"Diana Lopez",
""
]
] | We show how the quantum to classical transition of the cosmological fluctuations produced during inflation can be described by means of the influence functional and the master equation. We split the inflaton field into the system-field (long-wavelength modes), and the environment, represented by its own short-wavelength modes. We compute the decoherence times for the system-field modes and compare them with the other time scales of the model. We present the renormalized stochastic Langevin equation for an homogeneous system-field and then we analyze the influence of the environment on the power spectrum for some modes in the system. |
0912.5154 | Branislav Cvetkovi\'c | M. Blagojevi\'c and B. Cvetkovi\'c | Asymptotic Chern-Simons formulation of spacelike stretched AdS gravity | LATEX, 21 pages; v2: improved presentation, section 6 extended, two
references added | Class.Quant.Grav.27:185022,2010 | 10.1088/0264-9381/27/18/185022 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the asymptotic structures of topologically massive gravity in
the spacelike stretched AdS sector and an $SL(2,R)\times U(1)$ Chern-Simons
gauge theory can be identified by adopting a natural correspondence between
their fields and coupling constants.
| [
{
"created": "Mon, 28 Dec 2009 11:03:49 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Aug 2010 10:06:28 GMT",
"version": "v2"
}
] | 2014-11-20 | [
[
"Blagojević",
"M.",
""
],
[
"Cvetković",
"B.",
""
]
] | We show that the asymptotic structures of topologically massive gravity in the spacelike stretched AdS sector and an $SL(2,R)\times U(1)$ Chern-Simons gauge theory can be identified by adopting a natural correspondence between their fields and coupling constants. |
2005.09728 | Roxana Rosca-Mead | Roxana Rosca-Mead, Ulrich Sperhake, Christopher J. Moore, Michalis
Agathos, Davide Gerosa and Christian D. Ott | Core collapse in massive scalar-tensor gravity | 26 pages, 19 figures, to match published version in Phys.Rev.D | Phys. Rev. D 102, 044010 (2020) | 10.1103/PhysRevD.102.044010 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper provides an extended exploration of the inverse-chirp
gravitational-wave signals from stellar collapse in massive scalar-tensor
gravity reported in [Phys. Rev. Lett. {\bf 119}, 201103]. We systematically
explore the parameter space that characterizes the progenitor stars, the
equation of state and the scalar-tensor theory of the core collapse events. We
identify a remarkably simple and straightforward classification scheme of the
resulting collapse events. For any given set of parameters, the collapse leads
to one of three end states, a weakly scalarized neutron star, a strongly
scalarized neutron star or a black hole, possibly formed in multiple stages.
The latter two end states can lead to strong gravitational-wave signals that
may be detectable in present continuous-wave searches with ground-based
detectors. We identify a very sharp boundary in the parameter space that
separates events with strong gravitational-wave emission from those with
negligible radiation.
| [
{
"created": "Tue, 19 May 2020 19:57:50 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Sep 2020 13:58:58 GMT",
"version": "v2"
}
] | 2020-09-16 | [
[
"Rosca-Mead",
"Roxana",
""
],
[
"Sperhake",
"Ulrich",
""
],
[
"Moore",
"Christopher J.",
""
],
[
"Agathos",
"Michalis",
""
],
[
"Gerosa",
"Davide",
""
],
[
"Ott",
"Christian D.",
""
]
] | This paper provides an extended exploration of the inverse-chirp gravitational-wave signals from stellar collapse in massive scalar-tensor gravity reported in [Phys. Rev. Lett. {\bf 119}, 201103]. We systematically explore the parameter space that characterizes the progenitor stars, the equation of state and the scalar-tensor theory of the core collapse events. We identify a remarkably simple and straightforward classification scheme of the resulting collapse events. For any given set of parameters, the collapse leads to one of three end states, a weakly scalarized neutron star, a strongly scalarized neutron star or a black hole, possibly formed in multiple stages. The latter two end states can lead to strong gravitational-wave signals that may be detectable in present continuous-wave searches with ground-based detectors. We identify a very sharp boundary in the parameter space that separates events with strong gravitational-wave emission from those with negligible radiation. |
2310.10968 | Osvaldo Pablo Santillan | L. Lanosa and O. Santillan | Peculiarities for domain walls in Taub coordinates | 19 pages and 3 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present letter the infinite domain wall geometry in GR
\cite{vilenkin1}-\cite{ipser} is reconsidered in Taub coordinates \cite{taub}.
The use of these coordinates makes explicit that the regions between the
horizons and the wall and the outer ones are flat. By use of these coordinates,
it is suggested that points inside the horizon and outside never communicate
each other. The wall is seen on the left and the right side as contracting and
expanding portions of spheres and a plane singularity, which is the imprint the
contracting and expanding domain wall. Particles of each region will never
reach this imprint. In addition, at some point during the evolution of the
system, four curious holes inside the space time appear, growing at the speed
of light. This region is not parameterized by the standard Taub coordinates,
and the boundary of this hole adsorbs all the particles that intersect it. The
boundary of these holes are composed by points which in the coordinates of
\cite{vilenkin1}-\cite{ipser} are asymptotic, in the sense that they correspond
to trajectories tending to infinite values of the time or space like
coordinates, while the proper time elapsed for the travel is in fact finite.
This is not paradoxical, as the coordinates \cite{vilenkin1}-\cite{ipser} are
not to be identified with the true lengths or proper time on the space time.
The correct interpretation of the boundary is particularity relevant when
studying scattering of quantum fields approaching the domain wall. A partial
analysis about this issue is done in the last section.
| [
{
"created": "Tue, 17 Oct 2023 03:29:14 GMT",
"version": "v1"
}
] | 2023-10-18 | [
[
"Lanosa",
"L.",
""
],
[
"Santillan",
"O.",
""
]
] | In the present letter the infinite domain wall geometry in GR \cite{vilenkin1}-\cite{ipser} is reconsidered in Taub coordinates \cite{taub}. The use of these coordinates makes explicit that the regions between the horizons and the wall and the outer ones are flat. By use of these coordinates, it is suggested that points inside the horizon and outside never communicate each other. The wall is seen on the left and the right side as contracting and expanding portions of spheres and a plane singularity, which is the imprint the contracting and expanding domain wall. Particles of each region will never reach this imprint. In addition, at some point during the evolution of the system, four curious holes inside the space time appear, growing at the speed of light. This region is not parameterized by the standard Taub coordinates, and the boundary of this hole adsorbs all the particles that intersect it. The boundary of these holes are composed by points which in the coordinates of \cite{vilenkin1}-\cite{ipser} are asymptotic, in the sense that they correspond to trajectories tending to infinite values of the time or space like coordinates, while the proper time elapsed for the travel is in fact finite. This is not paradoxical, as the coordinates \cite{vilenkin1}-\cite{ipser} are not to be identified with the true lengths or proper time on the space time. The correct interpretation of the boundary is particularity relevant when studying scattering of quantum fields approaching the domain wall. A partial analysis about this issue is done in the last section. |
gr-qc/9702018 | Leonid Grishchuk | L. P. Grishchuk and J\'er\^ome Martin | Best Unbiased Estimates for the Microwave Background Anisotropies | 26 pages, revtex; minor modifications, 8 new references, to be
published in Phys. Rev. D | Phys. Rev. D 56, 1924 (1997) | 10.1103/PhysRevD.56.1924 | null | gr-qc astro-ph hep-ph | null | It is likely that the observed distribution of the microwave background
temperature over the sky is only one realization of the underlying random
process associated with cosmological perturbations of quantum-mechanical
origin. If so, one needs to derive the parameters of the random process, as
accurately as possible, from the data of a single map. These parameters are of
the utmost importance, since our knowledge of them would help us to reconstruct
the dynamical evolution of the very early Universe. It appears that the lack of
ergodicity of a random process on a 2-sphere does not allow us to do this with
arbitrarily high accuracy. We are left with the problem of finding the best
unbiased estimators of the participating parameters. A detailed solution to
this problem is presented in this article. The theoretical error bars for the
best unbiased estimates are derived and discussed.
| [
{
"created": "Mon, 10 Feb 1997 17:15:41 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Jun 1997 10:48:37 GMT",
"version": "v2"
}
] | 2016-08-24 | [
[
"Grishchuk",
"L. P.",
""
],
[
"Martin",
"Jérôme",
""
]
] | It is likely that the observed distribution of the microwave background temperature over the sky is only one realization of the underlying random process associated with cosmological perturbations of quantum-mechanical origin. If so, one needs to derive the parameters of the random process, as accurately as possible, from the data of a single map. These parameters are of the utmost importance, since our knowledge of them would help us to reconstruct the dynamical evolution of the very early Universe. It appears that the lack of ergodicity of a random process on a 2-sphere does not allow us to do this with arbitrarily high accuracy. We are left with the problem of finding the best unbiased estimators of the participating parameters. A detailed solution to this problem is presented in this article. The theoretical error bars for the best unbiased estimates are derived and discussed. |
0711.0250 | K G Arun | K G Arun, Luc Blanchet, Bala R Iyer and Moh'd S S Qusailah | Tail effects in the third post-Newtonian gravitational wave energy flux
of compact binaries in quasi-elliptical orbits | 32 pages, 10 figures. Minor changes in text throughout. Matches the
published version | Phys. Rev. D 77, 064034 (2008) | 10.1103/PhysRevD.77.064034 | null | gr-qc | null | The far-zone flux of energy contains hereditary (tail) contributions that
depend on the entire past history of the source. Using the multipolar
post-Minkowskian wave generation formalism, we propose and implement a
semi-analytical method in the frequency domain to compute these contributions
from the inspiral phase of a binary system of compact objects moving in
quasi-elliptical orbits up to 3PN order. The method explicitly uses the
quasi-Keplerian representation of elliptical orbits at 1PN order and exploits
the doubly periodic nature of the motion to average the 3PN fluxes over the
binary's orbit. Together with the instantaneous (non-tail) contributions
evaluated in a companion paper, it provides crucial inputs for the construction
of ready-to-use templates for compact binaries moving on quasi-elliptic orbits,
an interesting class of sources for the ground based gravitational wave
detectors such as LIGO and Virgo as well as space based detectors like LISA.
| [
{
"created": "Fri, 2 Nov 2007 13:07:09 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Apr 2008 21:46:57 GMT",
"version": "v2"
}
] | 2009-11-13 | [
[
"Arun",
"K G",
""
],
[
"Blanchet",
"Luc",
""
],
[
"Iyer",
"Bala R",
""
],
[
"Qusailah",
"Moh'd S S",
""
]
] | The far-zone flux of energy contains hereditary (tail) contributions that depend on the entire past history of the source. Using the multipolar post-Minkowskian wave generation formalism, we propose and implement a semi-analytical method in the frequency domain to compute these contributions from the inspiral phase of a binary system of compact objects moving in quasi-elliptical orbits up to 3PN order. The method explicitly uses the quasi-Keplerian representation of elliptical orbits at 1PN order and exploits the doubly periodic nature of the motion to average the 3PN fluxes over the binary's orbit. Together with the instantaneous (non-tail) contributions evaluated in a companion paper, it provides crucial inputs for the construction of ready-to-use templates for compact binaries moving on quasi-elliptic orbits, an interesting class of sources for the ground based gravitational wave detectors such as LIGO and Virgo as well as space based detectors like LISA. |
gr-qc/0609132 | Samad Khakshournia | S. Ghassemi, S. Khakshournia, and R. Mansouri | Thick planar domain wall: its thin wall limit and dynamics | 11 pages, to appear in IJMPD | Int.J.Mod.Phys.D16:629-640,2007 | 10.1142/S0218271807009395 | null | gr-qc | null | We consider a planar gravitating thick domain wall of the $\lambda \phi^4$
theory as a spacetime with finite thickness glued to two vacuum spacetimes on
each side of it. Darmois junction conditions written on the boundaries of the
thick wall with the embedding spacetimes reproduce the Israel junction
condition across the wall in the limit of infinitesimal thickness. The thick
planar domain wall located at a fixed position is then transformed to a new
coordinate system in which its dynamics can be formulated. It is shown that the
wall's core expands as if it were a thin wall. The thickness in the new
coordinates is not constant anymore and its time dependence is given.
| [
{
"created": "Thu, 28 Sep 2006 10:09:43 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Ghassemi",
"S.",
""
],
[
"Khakshournia",
"S.",
""
],
[
"Mansouri",
"R.",
""
]
] | We consider a planar gravitating thick domain wall of the $\lambda \phi^4$ theory as a spacetime with finite thickness glued to two vacuum spacetimes on each side of it. Darmois junction conditions written on the boundaries of the thick wall with the embedding spacetimes reproduce the Israel junction condition across the wall in the limit of infinitesimal thickness. The thick planar domain wall located at a fixed position is then transformed to a new coordinate system in which its dynamics can be formulated. It is shown that the wall's core expands as if it were a thin wall. The thickness in the new coordinates is not constant anymore and its time dependence is given. |
1207.6810 | Marcos Ramirez | Marcos A. Ramirez | Self-gravitating splitting thin shells | 18 pages, 3 figures | Class. Quantum Grav. 32 085005 (2015) | 10.1088/0264-9381/32/8/085005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we show that thin shells in spherically symmetric spacetimes,
whose matter content is described by a pair of non-interacting spherically
symmetric matter fields, generically exhibit instability against an
infinitesimal separation of its constituent fields. We give explicit examples
and construct solutions that represent a shell that splits into two shells.
Then we extend those results for 5-dimensional Schwarzschild-AdS bulk
spacetimes, which is a typical scenario for brane-world models, and show that
the same kind of stability analysis and splitting solution can be constructed.
We find that a widely proposed family of brane-world models are extremely
unstable in this sense. Finally, we discuss possible interpretations of these
features and their relation to the initial value problem for concentrated
sources.
| [
{
"created": "Sun, 29 Jul 2012 23:53:27 GMT",
"version": "v1"
},
{
"created": "Wed, 15 Aug 2012 23:56:52 GMT",
"version": "v2"
},
{
"created": "Tue, 23 Oct 2012 04:47:28 GMT",
"version": "v3"
},
{
"created": "Fri, 29 Aug 2014 23:07:17 GMT",
"version": "v4"
},
{
"c... | 2015-04-01 | [
[
"Ramirez",
"Marcos A.",
""
]
] | In this paper we show that thin shells in spherically symmetric spacetimes, whose matter content is described by a pair of non-interacting spherically symmetric matter fields, generically exhibit instability against an infinitesimal separation of its constituent fields. We give explicit examples and construct solutions that represent a shell that splits into two shells. Then we extend those results for 5-dimensional Schwarzschild-AdS bulk spacetimes, which is a typical scenario for brane-world models, and show that the same kind of stability analysis and splitting solution can be constructed. We find that a widely proposed family of brane-world models are extremely unstable in this sense. Finally, we discuss possible interpretations of these features and their relation to the initial value problem for concentrated sources. |
1307.8086 | Huan Yang | Huan Yang, Aaron Zimmerman, An{\i}l Zengino\u{g}lu, Fan Zhang,
Emanuele Berti and Yanbei Chen | Quasinormal modes of nearly extremal Kerr spacetimes: spectrum
bifurcation and power-law ringdown | 23 pages, 15 figures | Phys. Rev. D 88, 044047 (2013) | 10.1103/PhysRevD.88.044047 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide an in-depth investigation of quasinormal-mode oscillations of Kerr
black holes with nearly extremal angular momenta. We first discuss in greater
detail the two distinct types of quasinormal mode frequencies presented in a
recent paper (arXiv:1212.3271). One set of modes, that we call "zero-damping
modes", has vanishing imaginary part in the extremal limit, and exists for all
corotating perturbations (i.e., modes with azimuthal index m being
nonnegative). The other set (the "damped modes") retains a finite decay rate
even for extremal Kerr black holes, and exists only for a subset of corotating
modes. As the angular momentum approaches its extremal value, the frequency
spectrum bifurcates into these two distinct branches when both types of modes
are present. We discuss the physical reason for the mode branching by
developing and using a bound-state formulation for the perturbations of generic
Kerr black holes. We also numerically explore the specific case of the
fundamental l=2 modes, which have the greatest astrophysical interest. Using
the results of these investigations, we compute the quasinormal mode response
of a nearly extremal Kerr black hole to perturbations. We show that many
superimposed overtones result in a slow power-law decay of the quasinormal
ringing at early times, which later gives way to exponential decay. This
exceptional early-time power-law decay implies that the ringdown phase is
long-lived for black holes with large angular momentum, which could provide a
promising strong source for gravitational-wave detectors.
| [
{
"created": "Tue, 30 Jul 2013 19:09:02 GMT",
"version": "v1"
}
] | 2013-08-28 | [
[
"Yang",
"Huan",
""
],
[
"Zimmerman",
"Aaron",
""
],
[
"Zenginoğlu",
"Anıl",
""
],
[
"Zhang",
"Fan",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Chen",
"Yanbei",
""
]
] | We provide an in-depth investigation of quasinormal-mode oscillations of Kerr black holes with nearly extremal angular momenta. We first discuss in greater detail the two distinct types of quasinormal mode frequencies presented in a recent paper (arXiv:1212.3271). One set of modes, that we call "zero-damping modes", has vanishing imaginary part in the extremal limit, and exists for all corotating perturbations (i.e., modes with azimuthal index m being nonnegative). The other set (the "damped modes") retains a finite decay rate even for extremal Kerr black holes, and exists only for a subset of corotating modes. As the angular momentum approaches its extremal value, the frequency spectrum bifurcates into these two distinct branches when both types of modes are present. We discuss the physical reason for the mode branching by developing and using a bound-state formulation for the perturbations of generic Kerr black holes. We also numerically explore the specific case of the fundamental l=2 modes, which have the greatest astrophysical interest. Using the results of these investigations, we compute the quasinormal mode response of a nearly extremal Kerr black hole to perturbations. We show that many superimposed overtones result in a slow power-law decay of the quasinormal ringing at early times, which later gives way to exponential decay. This exceptional early-time power-law decay implies that the ringdown phase is long-lived for black holes with large angular momentum, which could provide a promising strong source for gravitational-wave detectors. |
1009.0608 | Fumihiko Ishiyama | Fumihiko Ishiyama, Ryutaro Takahashi | The bounce hardness index of gravitational waves | 13 pages, 7figures | Class.Quant.Grav.27:245021,2010 | 10.1088/0264-9381/27/24/245021 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a method of mode analysis to search for signals with frequency
evolution and limited duration in a given data stream. Our method is a natural
expansion of the Fourier analysis, and we can obtain the information about
frequency evolution with high frequency precision and high time resolution.
Applications of this method to the analysis of inspiral and burst signals show
that the signals are characterized by an index which we name `bounce hardness'.
The index corresponds to the growth rate of the signals.
| [
{
"created": "Fri, 3 Sep 2010 08:55:37 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Dec 2010 07:21:12 GMT",
"version": "v2"
}
] | 2024-03-26 | [
[
"Ishiyama",
"Fumihiko",
""
],
[
"Takahashi",
"Ryutaro",
""
]
] | We present a method of mode analysis to search for signals with frequency evolution and limited duration in a given data stream. Our method is a natural expansion of the Fourier analysis, and we can obtain the information about frequency evolution with high frequency precision and high time resolution. Applications of this method to the analysis of inspiral and burst signals show that the signals are characterized by an index which we name `bounce hardness'. The index corresponds to the growth rate of the signals. |
0912.4001 | Niall \'O Murchadha | Niall O Murchadha, Roh-Suan Tung, Naqing Xie, Edward Malec | The Brown-York mass and the Thorne hoop conjecture | 4 pages; accepted for publication in Physical Review Letters | Phys.Rev.Lett.104:041101,2010 | 10.1103/PhysRevLett.104.041101 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Thorne hoop conjecture is an attempt to make precise the notion that
gravitational collapse occurs if enough energy is compressed into a small
enough volume, with the `size' being defined by the circumference. We can make
a precise statement of this form, in spherical symmetry, using the Brown-York
mass as our measure of the energy. Consider a spherical 2-surface in a
spherically symmetric spacetime. If the Brown-York mass, $M_{BY}$, and the
circumference, $C$, satisfy $C < 2\pi M_{BY}$, then the system must either have
emerged from a white hole or will collapse into a black hole. We show that no
equivalent result can hold true using either the Liu-Yau mass, $M_{LY}$ or the
Wang-Yau mass, $M_{WY}$. This forms a major obstacle to any attempt to
establish a Thorne-type hoop theorem in the general case based on either the
Liu-Yau or the Wang-Yau mass.
| [
{
"created": "Sun, 20 Dec 2009 11:55:37 GMT",
"version": "v1"
}
] | 2010-11-11 | [
[
"Murchadha",
"Niall O",
""
],
[
"Tung",
"Roh-Suan",
""
],
[
"Xie",
"Naqing",
""
],
[
"Malec",
"Edward",
""
]
] | The Thorne hoop conjecture is an attempt to make precise the notion that gravitational collapse occurs if enough energy is compressed into a small enough volume, with the `size' being defined by the circumference. We can make a precise statement of this form, in spherical symmetry, using the Brown-York mass as our measure of the energy. Consider a spherical 2-surface in a spherically symmetric spacetime. If the Brown-York mass, $M_{BY}$, and the circumference, $C$, satisfy $C < 2\pi M_{BY}$, then the system must either have emerged from a white hole or will collapse into a black hole. We show that no equivalent result can hold true using either the Liu-Yau mass, $M_{LY}$ or the Wang-Yau mass, $M_{WY}$. This forms a major obstacle to any attempt to establish a Thorne-type hoop theorem in the general case based on either the Liu-Yau or the Wang-Yau mass. |
1406.7661 | Leonardo Gualtieri | Gr\'egoire Martinon, Andrea Maselli, Leonardo Gualtieri, Valeria
Ferrari | Rotating proto-neutron stars: spin evolution, maximum mass and I-Love-Q
relations | 15 pages, 9 figures, 7 tables; minor changes, and extended discussion
on the I-Love-Q relations | null | 10.1103/PhysRevD.90.064026 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Shortly after its birth in a gravitational collapse, a proto-neutron star
enters in a phase of quasi-stationary evolution characterized by large
gradients of the thermodynamical variables and intense neutrino emission. In
few tens of seconds the gradients smooth out while the star contracts and cools
down, until it becomes a neutron star. In this paper we study this phase of the
proto-neutron star life including rotation, and employing finite temperature
equations of state. We model the evolution of the rotation rate, and determine
the relevant quantities characterizing the star. Our results show that an
isolated neutron star cannot reach, at the end of the evolution, the maximum
values of mass and rotation rate allowed by the zero-temperature equation of
state. Moreover, a mature neutron star evolved in isolation cannot rotate too
rapidly, even if it is born from a proto-neutron star rotating at the
mass-shedding limit. We also show that the I-Love-Q relations are violated in
the first second of life, but they are satisfied as soon as the entropy
gradients smooth out.
| [
{
"created": "Mon, 30 Jun 2014 10:44:12 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Jul 2014 20:30:38 GMT",
"version": "v2"
}
] | 2015-06-22 | [
[
"Martinon",
"Grégoire",
""
],
[
"Maselli",
"Andrea",
""
],
[
"Gualtieri",
"Leonardo",
""
],
[
"Ferrari",
"Valeria",
""
]
] | Shortly after its birth in a gravitational collapse, a proto-neutron star enters in a phase of quasi-stationary evolution characterized by large gradients of the thermodynamical variables and intense neutrino emission. In few tens of seconds the gradients smooth out while the star contracts and cools down, until it becomes a neutron star. In this paper we study this phase of the proto-neutron star life including rotation, and employing finite temperature equations of state. We model the evolution of the rotation rate, and determine the relevant quantities characterizing the star. Our results show that an isolated neutron star cannot reach, at the end of the evolution, the maximum values of mass and rotation rate allowed by the zero-temperature equation of state. Moreover, a mature neutron star evolved in isolation cannot rotate too rapidly, even if it is born from a proto-neutron star rotating at the mass-shedding limit. We also show that the I-Love-Q relations are violated in the first second of life, but they are satisfied as soon as the entropy gradients smooth out. |
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