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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2206.09267 | S. N Sajadi | S.H. Hendi, N. Riazi, S.N. Sajadi | Quantum Cosmology in Thick Brane | 10 pages, 5 figures. arXiv admin note: text overlap with
arXiv:2011.11093 | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | One of the interesting open problems in the cosmological framework is
applying quantum physics to the whole universe, consistently. Although
different conceptual aspects of quantum cosmology are still very much alive,
till now, all the attempts of obtaining a unique and well-defined version of
quantum cosmology have been unfeasible. Motivated by what was mentioned above,
in this paper, the quantum tunneling of thick brane is investigated by deriving
the Wheeler-DeWitt equation and corresponding solutions. Besides, the
cosmological analysis of the brane is studied based on two special cases of the
scalar field. Finally, it is found that the constant scalar potential arising
from a time-dependent scalar field is supported by the so-called slow-roll
inflation.
| [
{
"created": "Sat, 18 Jun 2022 18:49:27 GMT",
"version": "v1"
}
] | 2022-06-22 | [
[
"Hendi",
"S. H.",
""
],
[
"Riazi",
"N.",
""
],
[
"Sajadi",
"S. N.",
""
]
] | One of the interesting open problems in the cosmological framework is applying quantum physics to the whole universe, consistently. Although different conceptual aspects of quantum cosmology are still very much alive, till now, all the attempts of obtaining a unique and well-defined version of quantum cosmology have been unfeasible. Motivated by what was mentioned above, in this paper, the quantum tunneling of thick brane is investigated by deriving the Wheeler-DeWitt equation and corresponding solutions. Besides, the cosmological analysis of the brane is studied based on two special cases of the scalar field. Finally, it is found that the constant scalar potential arising from a time-dependent scalar field is supported by the so-called slow-roll inflation. |
gr-qc/0111008 | Kayll Lake | Mustapha Ishak and Kayll Lake | An Online Interactive Geometric Database: Including Exact Solutions of
Einstein's Field Equations | 11 pages revtex4 4 figures. Final form to appear in Class. Quantum
Grav. Further information at http://grdb.org | Class.Quant.Grav. 19 (2002) 505-514 | 10.1088/0264-9381/19/3/306 | null | gr-qc | null | We describe a new interactive database (GRDB) of geometric objects in the
general area of differential geometry. Database objects include, but are not
restricted to, exact solutions of Einstein's field equations. GRDB is designed
for researchers (and teachers) in applied mathematics, physics and related
fields. The flexible search environment allows the database to be useful over a
wide spectrum of interests, for example, from practical considerations of
neutron star models in astrophysics to abstract space-time classification
schemes. The database is built using a modular and object-oriented design and
uses several Java technologies (e.g. Applets, Servlets, JDBC). These are
platform-independent and well adapted for applications developed to run over
the World Wide Web. GRDB is accompanied by a virtual calculator (GRTensorJ), a
graphical user interface to the computer algebra system GRTensorII used to
perform online coordinate, tetrad or basis calculations. The highly interactive
nature of GRDB allows for systematic internal self-checking and a minimization
of the required internal records.
| [
{
"created": "Fri, 2 Nov 2001 22:23:23 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Dec 2001 22:07:57 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Ishak",
"Mustapha",
""
],
[
"Lake",
"Kayll",
""
]
] | We describe a new interactive database (GRDB) of geometric objects in the general area of differential geometry. Database objects include, but are not restricted to, exact solutions of Einstein's field equations. GRDB is designed for researchers (and teachers) in applied mathematics, physics and related fields. The flexible search environment allows the database to be useful over a wide spectrum of interests, for example, from practical considerations of neutron star models in astrophysics to abstract space-time classification schemes. The database is built using a modular and object-oriented design and uses several Java technologies (e.g. Applets, Servlets, JDBC). These are platform-independent and well adapted for applications developed to run over the World Wide Web. GRDB is accompanied by a virtual calculator (GRTensorJ), a graphical user interface to the computer algebra system GRTensorII used to perform online coordinate, tetrad or basis calculations. The highly interactive nature of GRDB allows for systematic internal self-checking and a minimization of the required internal records. |
1905.02389 | Fabrizio Tamburini | I. Licata, G. Iovane, L. Chiatti, E. Benedetto, F. Tamburini | Dark Universe and distribution of Matter as Quantum Imprinting: the
Quantum Origin of Universe | 18 pages | Physics of the Dark Universe 22 (2018) 181-188 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we analyze the Dark Matter problem and the distribution of
matter through two different approaches, which are linked by the possibility
that the solution of these astronomical puzzles should be sought in the quantum
imprinting of the Universe. The first approach is based on a cosmological model
formulated and developed in the last ten years by the first and third authors
of this paper; the so-called Archaic Universe. The second approach was
formulated by Rosen in 1933 by considering the Friedmann-Einstein equations as
a simple one-dimensional dynamical system reducing the cosmological equations
in terms of a Schroedinger equation. As an example, the quantum memory in
cosmological dynamics could explain the apparently periodic structures of the
Universe while Archaic Universe shows how the quantum phase concernts not only
an ancient era of the Universe, but quantum facets permeating the entire
Universe today.
| [
{
"created": "Tue, 7 May 2019 07:22:14 GMT",
"version": "v1"
}
] | 2019-05-08 | [
[
"Licata",
"I.",
""
],
[
"Iovane",
"G.",
""
],
[
"Chiatti",
"L.",
""
],
[
"Benedetto",
"E.",
""
],
[
"Tamburini",
"F.",
""
]
] | In this paper we analyze the Dark Matter problem and the distribution of matter through two different approaches, which are linked by the possibility that the solution of these astronomical puzzles should be sought in the quantum imprinting of the Universe. The first approach is based on a cosmological model formulated and developed in the last ten years by the first and third authors of this paper; the so-called Archaic Universe. The second approach was formulated by Rosen in 1933 by considering the Friedmann-Einstein equations as a simple one-dimensional dynamical system reducing the cosmological equations in terms of a Schroedinger equation. As an example, the quantum memory in cosmological dynamics could explain the apparently periodic structures of the Universe while Archaic Universe shows how the quantum phase concernts not only an ancient era of the Universe, but quantum facets permeating the entire Universe today. |
2003.04723 | Emil Nissimov | David Benisty, Eduardo Guendelman, Emil Nissimov, Svetlana Pacheva | Quintessential Inflation with Dynamical Higgs Generation as an Affine
Gravity | 17 pages, 1 figure; v.2 few clarifications and several new citations
added, accepted for publication in "Symmetry", Special issue "Global and
Local Scale Symmetry in Gravitation and Cosmology"; partial overlap with
arXiv:2002.04110 | Symmetry 2020, 12, 734 (Special issue on "Global and Local Scale
Symmetry in Gravitationa and Cosmology") | 10.3390/sym12050734 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | First, we propose a scale-invariant modified gravity interacting with a
neutral scalar "inflaton" and a Higgs-like SU(2)xU(1) iso-doublet scalar field
based on the formalism of non-Riemannian (metric-independent) spacetime
volume-elements. This model describes in the physical Einstein frame a
quintessential inflationary scenario driven by the "inflaton" together with
gravity-inflaton assisted dynamical spontaneous SU(2)xU(1) symmetry breaking in
the post-inflationary universe, whereas SU(2)xU(1) symmetry remains intact in
the inflationary epoch. Next, we find the explicit representation of the latter
quintessential inflationary model with a dynamical Higgs effect as an
Eddington-type purely affine gravity.
| [
{
"created": "Sat, 7 Mar 2020 20:38:58 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Apr 2020 10:19:05 GMT",
"version": "v2"
}
] | 2020-05-14 | [
[
"Benisty",
"David",
""
],
[
"Guendelman",
"Eduardo",
""
],
[
"Nissimov",
"Emil",
""
],
[
"Pacheva",
"Svetlana",
""
]
] | First, we propose a scale-invariant modified gravity interacting with a neutral scalar "inflaton" and a Higgs-like SU(2)xU(1) iso-doublet scalar field based on the formalism of non-Riemannian (metric-independent) spacetime volume-elements. This model describes in the physical Einstein frame a quintessential inflationary scenario driven by the "inflaton" together with gravity-inflaton assisted dynamical spontaneous SU(2)xU(1) symmetry breaking in the post-inflationary universe, whereas SU(2)xU(1) symmetry remains intact in the inflationary epoch. Next, we find the explicit representation of the latter quintessential inflationary model with a dynamical Higgs effect as an Eddington-type purely affine gravity. |
1610.07346 | Prado Martin-Moruno | Mariam Bouhmadi-L\'opez, Salvatore Capozziello, Prado Mart\'in-Moruno | Self-acceleration and matter content in bicosmology from Noether
Symmetries | V1: 23 pages. V2: 7 references added. V3: clarifications in the
discussion; no physics changes; 5 references added; 16 pages. V4: minor
changes; 1 reference added. This version accepted for publication in General
Relativity and Gravitation | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In bigravity, when taking into account the potential existence of matter
fields minimally coupled to the second gravitation sector, the dynamics of our
Universe depends on some matter that cannot be observed in a direct way. In
this paper, we assume the existence of a Noether symmetry in bigravity
cosmologies in order to constrain the dynamics of that matter. By imposing this
assumption we obtain cosmological models with interesting phenomenology. In
fact, considering that our universe is filled with standard matter and
radiation, we show that the existence of a Noether symmetry implies that either
the dynamics of the second sector decouples, being the model equivalent to
General Relativity, or the cosmological evolution of our universe tends to a de
Sitter state with the vacuum energy in it given by the conserved quantity
associated with the symmetry. The physical consequences of the genuine
bigravity models obtained are briefly discussed. We also point out that the
first model, which is equivalent to General Relativity, may be favored due to
the potential appearance of instabilities in the second model.
| [
{
"created": "Mon, 24 Oct 2016 10:08:53 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Oct 2016 09:56:17 GMT",
"version": "v2"
},
{
"created": "Mon, 10 Apr 2017 10:12:42 GMT",
"version": "v3"
},
{
"created": "Thu, 1 Mar 2018 13:23:13 GMT",
"version": "v4"
}
] | 2018-03-02 | [
[
"Bouhmadi-López",
"Mariam",
""
],
[
"Capozziello",
"Salvatore",
""
],
[
"Martín-Moruno",
"Prado",
""
]
] | In bigravity, when taking into account the potential existence of matter fields minimally coupled to the second gravitation sector, the dynamics of our Universe depends on some matter that cannot be observed in a direct way. In this paper, we assume the existence of a Noether symmetry in bigravity cosmologies in order to constrain the dynamics of that matter. By imposing this assumption we obtain cosmological models with interesting phenomenology. In fact, considering that our universe is filled with standard matter and radiation, we show that the existence of a Noether symmetry implies that either the dynamics of the second sector decouples, being the model equivalent to General Relativity, or the cosmological evolution of our universe tends to a de Sitter state with the vacuum energy in it given by the conserved quantity associated with the symmetry. The physical consequences of the genuine bigravity models obtained are briefly discussed. We also point out that the first model, which is equivalent to General Relativity, may be favored due to the potential appearance of instabilities in the second model. |
1503.06085 | Lee Smolin | Marina Cortes, Henrique Gomes and Lee Smolin | Time asymmetric extensions of general relativity | 19 pages, LaTex, no figures | Phys. Rev. D 92, 043502 (2015) | 10.1103/PhysRevD.92.043502 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe a class of modified gravity theories that deform general
relativity in a way that breaks time reversal invariance and, very mildly,
locality. The algebra of constraints, local physical degrees of freedom, and
their linearized equations of motion, are unchanged, yet observable effects may
be present on cosmological scales, which have implications for the early
history of the universe.
This is achieved in the Hamiltonian framework, in a way that requires the
constant mean curvature gauge conditions and is, hence, inspired by shape
dynamics.
| [
{
"created": "Fri, 20 Mar 2015 14:28:37 GMT",
"version": "v1"
}
] | 2015-08-12 | [
[
"Cortes",
"Marina",
""
],
[
"Gomes",
"Henrique",
""
],
[
"Smolin",
"Lee",
""
]
] | We describe a class of modified gravity theories that deform general relativity in a way that breaks time reversal invariance and, very mildly, locality. The algebra of constraints, local physical degrees of freedom, and their linearized equations of motion, are unchanged, yet observable effects may be present on cosmological scales, which have implications for the early history of the universe. This is achieved in the Hamiltonian framework, in a way that requires the constant mean curvature gauge conditions and is, hence, inspired by shape dynamics. |
1107.4322 | Michele Levi | Michele Levi | Binary dynamics from spin1-spin2 coupling at fourth post-Newtonian order | 24 pages, revtex4-1, 5 figures; v2: typos fixed, added references;
v3: revised, published; v4: few omissions and typos corrected, minor edit | Phys.Rev.D85:064043,2012 | 10.1103/PhysRevD.85.064043 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We calculate via the effective field theory (EFT) approach the
next-to-next-to-leading order (NNLO) spin1-spin2 conservative potential for a
binary. Hereby, we first demonstrate the ability of the EFT approach to go at
NNLO in post-Newtonian (PN) corrections from spin effects. The NNLO spin1-spin2
interaction is evaluated at fourth PN order for a binary of maximally rotating
compact objects. This sector includes contributions from diagrams, which are
not pure spin1-spin2 diagrams, as they contribute through the leading-order
spin accelerations and precessions, that should be first taken into account
here. The fact that the spin is derivative-coupled adds significantly to the
complexity of computations. In particular, for the irreducible two-loop
diagrams, which are the most complicated to evaluate in this sector,
irreducible two-loop tensor integrals up to order 4 are required. The EFT
calculation is carried out in terms of the nonrelativistic gravitational (NRG)
fields. However, not all of the benefits of the NRG fields apply to spin
interactions, as all possible diagram topologies are realized at each order of
$G$ included. Still, the NRG fields remain advantageous, and thus there was no
use of automated computations in this work. Our final result can be reduced,
and a corresponding Hamiltonian may be derived.
| [
{
"created": "Thu, 21 Jul 2011 17:37:32 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Nov 2011 23:43:56 GMT",
"version": "v2"
},
{
"created": "Fri, 6 Apr 2012 12:26:49 GMT",
"version": "v3"
},
{
"created": "Wed, 25 Jun 2014 17:14:21 GMT",
"version": "v4"
}
] | 2014-06-26 | [
[
"Levi",
"Michele",
""
]
] | We calculate via the effective field theory (EFT) approach the next-to-next-to-leading order (NNLO) spin1-spin2 conservative potential for a binary. Hereby, we first demonstrate the ability of the EFT approach to go at NNLO in post-Newtonian (PN) corrections from spin effects. The NNLO spin1-spin2 interaction is evaluated at fourth PN order for a binary of maximally rotating compact objects. This sector includes contributions from diagrams, which are not pure spin1-spin2 diagrams, as they contribute through the leading-order spin accelerations and precessions, that should be first taken into account here. The fact that the spin is derivative-coupled adds significantly to the complexity of computations. In particular, for the irreducible two-loop diagrams, which are the most complicated to evaluate in this sector, irreducible two-loop tensor integrals up to order 4 are required. The EFT calculation is carried out in terms of the nonrelativistic gravitational (NRG) fields. However, not all of the benefits of the NRG fields apply to spin interactions, as all possible diagram topologies are realized at each order of $G$ included. Still, the NRG fields remain advantageous, and thus there was no use of automated computations in this work. Our final result can be reduced, and a corresponding Hamiltonian may be derived. |
gr-qc/9909046 | Dr. Bijan Modak | B.Modak, S. Kamilya and S.Biswas | Evolution of Dynamical Coupling in Scalar Tensor Theory from Noether
Symmetry | 7 Pages, ReVTeX, no figure | Gen.Rel.Grav. 32 (2000) 1615-1626 | 10.1023/A:1001990303511 | null | gr-qc | null | We present the gravitational coupling function $\omega(\phi)$ in the vacuum
scalar-tensor theory as allowed by the Noether symmetry. We also obtain some
exact cosmological solutions in the spatially homogeneous and isotropic
background thereby showing that the attractor mechanism is not effective enough
to reduce the theory to Einstein theory. It is observed that, asymptotically,
the scalar tensor theory goes over to Einstein theory with finite value of
$\omega$. This work thus supports earlier works in this direction.
| [
{
"created": "Wed, 15 Sep 1999 11:30:38 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Modak",
"B.",
""
],
[
"Kamilya",
"S.",
""
],
[
"Biswas",
"S.",
""
]
] | We present the gravitational coupling function $\omega(\phi)$ in the vacuum scalar-tensor theory as allowed by the Noether symmetry. We also obtain some exact cosmological solutions in the spatially homogeneous and isotropic background thereby showing that the attractor mechanism is not effective enough to reduce the theory to Einstein theory. It is observed that, asymptotically, the scalar tensor theory goes over to Einstein theory with finite value of $\omega$. This work thus supports earlier works in this direction. |
gr-qc/0610133 | Nikodem Poplawski | Nikodem J. Poplawski | The cosmic snap parameter in f(R) gravity | 9 pages; published version | Class.Quant.Grav.24:3013-3020,2007 | 10.1088/0264-9381/24/11/014 | null | gr-qc astro-ph | null | We derive the expression for the snap parameter in f(R) gravity. We use the
Palatini variational principle to obtain the field equations and regard the
Einstein conformal frame as physical. We predict the present-day value of the
snap parameter for the particular case f(R)=R-const/R, which is the simplest
f(R) model explaining the current acceleration of the universe.
| [
{
"created": "Fri, 27 Oct 2006 19:58:33 GMT",
"version": "v1"
},
{
"created": "Sun, 29 Oct 2006 20:36:16 GMT",
"version": "v2"
},
{
"created": "Tue, 22 May 2007 23:34:15 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Poplawski",
"Nikodem J.",
""
]
] | We derive the expression for the snap parameter in f(R) gravity. We use the Palatini variational principle to obtain the field equations and regard the Einstein conformal frame as physical. We predict the present-day value of the snap parameter for the particular case f(R)=R-const/R, which is the simplest f(R) model explaining the current acceleration of the universe. |
1812.11036 | Z. Yousaf | M. Shahzadi, Z. Yousaf, Saeed Ullah Khan | Circular Motion and Energy Extraction in a Rotating Black Hole | 24 pages, 9 figures | Phys. Dark Universe 24, 100263 (2019) | 10.1016/j.dark.2019.100263 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper explores the circular geodesics of neutral test particles on an
equatorial plane around a rotating black hole. After using equations of motion
of scalar-tensor-vector gravity with the circular geodesics of null-like
particles, we find the equation of photon orbit. With the help of an effective
potential form, we have examined the stable regimes of photons orbits. The
Lyapunov exponent, as well as the effective force acting on photons, is also
investigated. We examine the energy extraction from a black hole via Penrose
process. Furthermore, we discuss the negative energy state and the efficiency
of energy extraction. We have made compare our results with that obtained for
some well known black holes models. We concluded that the efficiency of the
energy extraction decreases with the increase of dimensionless parameter of
theory and increases as spin parameter increases.
| [
{
"created": "Tue, 18 Dec 2018 03:01:56 GMT",
"version": "v1"
}
] | 2021-01-08 | [
[
"Shahzadi",
"M.",
""
],
[
"Yousaf",
"Z.",
""
],
[
"Khan",
"Saeed Ullah",
""
]
] | This paper explores the circular geodesics of neutral test particles on an equatorial plane around a rotating black hole. After using equations of motion of scalar-tensor-vector gravity with the circular geodesics of null-like particles, we find the equation of photon orbit. With the help of an effective potential form, we have examined the stable regimes of photons orbits. The Lyapunov exponent, as well as the effective force acting on photons, is also investigated. We examine the energy extraction from a black hole via Penrose process. Furthermore, we discuss the negative energy state and the efficiency of energy extraction. We have made compare our results with that obtained for some well known black holes models. We concluded that the efficiency of the energy extraction decreases with the increase of dimensionless parameter of theory and increases as spin parameter increases. |
1303.4129 | Roseanne Cheng | Roseanne M. Cheng and Charles R. Evans | Relativistic effects in the tidal interaction between a white dwarf and
a massive black hole in Fermi normal coordinates | Updated to match published version, one reference added, one figure
changed | Phys. Rev. D 87, 104010 (2013) | 10.1103/PhysRevD.87.104010 | null | gr-qc astro-ph.HE astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider tidal encounters between a white dwarf and an intermediate mass
black hole. Both weak encounters and those at the threshold of disruption are
modeled. The numerical code combines mesh-based hydrodynamics, a spectral
method solution of the self-gravity, and a general relativistic Fermi normal
coordinate system that follows the star and debris. Fermi normal coordinates
provide an expansion of the black hole tidal field that includes quadrupole and
higher multipole moments and relativistic corrections. We compute the mass loss
from the white dwarf that occurs in weak tidal encounters. Secondly, we compute
carefully the energy deposition onto the star, examining the effects of
nonradial and radial mode excitation, surface layer heating, mass loss, and
relativistic orbital motion. We find evidence of a slight relativistic
suppression in tidal energy transfer. Tidal energy deposition is compared to
orbital energy loss due to gravitational bremsstrahlung and the combined losses
are used to estimate tidal capture orbits. Heating and partial mass stripping
will lead to an expansion of the white dwarf, making it easier for the star to
be tidally disrupted on the next passage. Finally, we examine angular momentum
deposition. By including the octupole tide, we are able for the first time to
calculate deflection of the center of mass of the star and debris. With this
observed deflection, and taking into account orbital relativistic effects, we
compute directly the change in orbital angular momentum and show its balance
with computed spin angular momentum deposition.
| [
{
"created": "Mon, 18 Mar 2013 01:28:01 GMT",
"version": "v1"
},
{
"created": "Wed, 8 May 2013 20:55:51 GMT",
"version": "v2"
}
] | 2013-05-10 | [
[
"Cheng",
"Roseanne M.",
""
],
[
"Evans",
"Charles R.",
""
]
] | We consider tidal encounters between a white dwarf and an intermediate mass black hole. Both weak encounters and those at the threshold of disruption are modeled. The numerical code combines mesh-based hydrodynamics, a spectral method solution of the self-gravity, and a general relativistic Fermi normal coordinate system that follows the star and debris. Fermi normal coordinates provide an expansion of the black hole tidal field that includes quadrupole and higher multipole moments and relativistic corrections. We compute the mass loss from the white dwarf that occurs in weak tidal encounters. Secondly, we compute carefully the energy deposition onto the star, examining the effects of nonradial and radial mode excitation, surface layer heating, mass loss, and relativistic orbital motion. We find evidence of a slight relativistic suppression in tidal energy transfer. Tidal energy deposition is compared to orbital energy loss due to gravitational bremsstrahlung and the combined losses are used to estimate tidal capture orbits. Heating and partial mass stripping will lead to an expansion of the white dwarf, making it easier for the star to be tidally disrupted on the next passage. Finally, we examine angular momentum deposition. By including the octupole tide, we are able for the first time to calculate deflection of the center of mass of the star and debris. With this observed deflection, and taking into account orbital relativistic effects, we compute directly the change in orbital angular momentum and show its balance with computed spin angular momentum deposition. |
1106.4357 | Ramin G. Daghigh | James Babb, Ramin G. Daghigh and Gabor Kunstatter | Highly Damped Quasinormal Modes and the Small Scale Structure of Quantum
Corrected Black Hole Exteriors | 32 pages, 7 figures | null | 10.1103/PhysRevD.84.084031 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quasinormal modes provide valuable information about the structure of
spacetime outside a black hole. There is also a conjectured relationship
between the highly damped quasinormal modes and the semi-classical spectrum of
the horizon area/entropy. In this paper, we show that for spacetimes
characterized by more than one scale, the "infinitely damped" modes in
principle probe the structure of spacetime outside the horizon at the shortest
length scales. We demonstrate this with the calculation of the highly damped
quasinormal modes of the non-singular, single horizon, quantum corrected black
hole derived in [14].
| [
{
"created": "Wed, 22 Jun 2011 00:48:18 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Babb",
"James",
""
],
[
"Daghigh",
"Ramin G.",
""
],
[
"Kunstatter",
"Gabor",
""
]
] | Quasinormal modes provide valuable information about the structure of spacetime outside a black hole. There is also a conjectured relationship between the highly damped quasinormal modes and the semi-classical spectrum of the horizon area/entropy. In this paper, we show that for spacetimes characterized by more than one scale, the "infinitely damped" modes in principle probe the structure of spacetime outside the horizon at the shortest length scales. We demonstrate this with the calculation of the highly damped quasinormal modes of the non-singular, single horizon, quantum corrected black hole derived in [14]. |
1911.04354 | Justin Feng | Justin C. Feng, Edgar Gasper\'in, Jarrod L. Williams | Almost-Killing equation: Stability, hyperbolicity, and black hole Gauss
law | 10 pages, 3 figures. Matches published version | Phys. Rev. D 100, 124034 (2019) | 10.1103/PhysRevD.100.124034 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the Hamiltonian formulation and hyperbolicity of the
almost-Killing equation (AKE). We find that for all but one parameter choice,
the Hamiltonian is unbounded, and in some cases, the AKE has ghost degrees of
freedom. We also show the AKE is only strongly hyperbolic for one parameter
choice, which corresponds to a case in which the AKE has ghosts. Fortunately,
one finds that the AKE reduces to the homogeneous Maxwell equation in a vacuum,
so that with the addition of the divergence-free constraint (a "Lorenz gauge"),
one can still obtain a well-posed problem that is stable in the sense that the
corresponding Hamiltonian is positive definite. An analysis of the resulting
Komar currents reveals an exact Gauss law for a system of black holes in vacuum
spacetimes and suggests a possible measure of matter content in asymptotically
flat spacetimes.
| [
{
"created": "Mon, 11 Nov 2019 15:56:53 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Dec 2019 16:47:59 GMT",
"version": "v2"
}
] | 2019-12-16 | [
[
"Feng",
"Justin C.",
""
],
[
"Gasperín",
"Edgar",
""
],
[
"Williams",
"Jarrod L.",
""
]
] | We examine the Hamiltonian formulation and hyperbolicity of the almost-Killing equation (AKE). We find that for all but one parameter choice, the Hamiltonian is unbounded, and in some cases, the AKE has ghost degrees of freedom. We also show the AKE is only strongly hyperbolic for one parameter choice, which corresponds to a case in which the AKE has ghosts. Fortunately, one finds that the AKE reduces to the homogeneous Maxwell equation in a vacuum, so that with the addition of the divergence-free constraint (a "Lorenz gauge"), one can still obtain a well-posed problem that is stable in the sense that the corresponding Hamiltonian is positive definite. An analysis of the resulting Komar currents reveals an exact Gauss law for a system of black holes in vacuum spacetimes and suggests a possible measure of matter content in asymptotically flat spacetimes. |
gr-qc/9906013 | John Klauder | John R. Klauder | Noncanonical Quantization of Gravity. I. Foundations of Affine Quantum
Gravity | minor changes, LaTeX, 37 pages, no figures | J.Math.Phys.40:5860-5882,1999 | 10.1063/1.533059 | null | gr-qc hep-th math-ph math.MP quant-ph | null | The nature of the classical canonical phase-space variables for gravity
suggests that the associated quantum field operators should obey affine
commutation relations rather than canonical commutation relations. Prior to the
introduction of constraints, a primary kinematical representation is derived in
the form of a reproducing kernel and its associated reproducing kernel Hilbert
space. Constraints are introduced following the projection operator method
which involves no gauge fixing, no complicated moduli space, nor any auxiliary
fields. The result, which is only qualitatively sketched in the present paper,
involves another reproducing kernel with which inner products are defined for
the physical Hilbert space and which is obtained through a reduction of the
original reproducing kernel. Several of the steps involved in this general
analysis are illustrated by means of analogous steps applied to one-dimensional
quantum mechanical models. These toy models help in motivating and
understanding the analysis in the case of gravity.
| [
{
"created": "Thu, 3 Jun 1999 20:49:24 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Jun 1999 21:01:12 GMT",
"version": "v2"
}
] | 2014-11-17 | [
[
"Klauder",
"John R.",
""
]
] | The nature of the classical canonical phase-space variables for gravity suggests that the associated quantum field operators should obey affine commutation relations rather than canonical commutation relations. Prior to the introduction of constraints, a primary kinematical representation is derived in the form of a reproducing kernel and its associated reproducing kernel Hilbert space. Constraints are introduced following the projection operator method which involves no gauge fixing, no complicated moduli space, nor any auxiliary fields. The result, which is only qualitatively sketched in the present paper, involves another reproducing kernel with which inner products are defined for the physical Hilbert space and which is obtained through a reduction of the original reproducing kernel. Several of the steps involved in this general analysis are illustrated by means of analogous steps applied to one-dimensional quantum mechanical models. These toy models help in motivating and understanding the analysis in the case of gravity. |
0805.3941 | Hyung Won Lee | Kyoung Yee Kim, Hyung Won Lee and Yun Soo Myung | Density perturbations in decaying holographic dark energy models | 11pages, 5 figures | null | 10.1142/S0217732309030643 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study cosmological perturbations in the context of an interacting dark
energy model, where the holographic dark energy with IR cutoff decays into the
cold dark matter (CDM). For this purpose, we introduce three IR cutoffs of
Hubble horizon, particle horizon, and future event horizon. Here we present
small perturbations under the case that effective equation of state (EOS:
$\omega^{\rm eff}$) for the holographic energy density is determined to be the
same negative constant as that for the CDM. Such new matter productions tend to
dilute the density perturbations of CDM (matter contrast). For a decelerating
universe of $\omega^{\rm eff}>-1/3$, the matter contrast is growing as the
universe evolves, while for an accelerating universe of $\omega^{\rm
eff}<-1/3$, the matter contrast is decaying, irrespective of the choice of IR
cutoff. This shows clearly that the acceleration suppresses the growing of the
density perturbations at the early universe.
| [
{
"created": "Mon, 26 May 2008 12:01:15 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Aug 2008 08:39:57 GMT",
"version": "v2"
}
] | 2015-05-13 | [
[
"Kim",
"Kyoung Yee",
""
],
[
"Lee",
"Hyung Won",
""
],
[
"Myung",
"Yun Soo",
""
]
] | We study cosmological perturbations in the context of an interacting dark energy model, where the holographic dark energy with IR cutoff decays into the cold dark matter (CDM). For this purpose, we introduce three IR cutoffs of Hubble horizon, particle horizon, and future event horizon. Here we present small perturbations under the case that effective equation of state (EOS: $\omega^{\rm eff}$) for the holographic energy density is determined to be the same negative constant as that for the CDM. Such new matter productions tend to dilute the density perturbations of CDM (matter contrast). For a decelerating universe of $\omega^{\rm eff}>-1/3$, the matter contrast is growing as the universe evolves, while for an accelerating universe of $\omega^{\rm eff}<-1/3$, the matter contrast is decaying, irrespective of the choice of IR cutoff. This shows clearly that the acceleration suppresses the growing of the density perturbations at the early universe. |
0912.3692 | Leonardo Gualtieri | V. Ferrari, L. Gualtieri, F. Pannarale | Neutron star tidal disruption in mixed binaries: the imprint of the
equation of state | 11 pages, 9 figures, 3 tables; references added | Phys.Rev.D81:064026,2010 | 10.1103/PhysRevD.81.064026 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the tidal disruption of neutron stars in black hole-neutron star
coalescing binaries. We calculate the critical orbital separation at which the
star is disrupted by the black hole tidal field for several equations of state
describing the matter inside the neutron star, and for a large set of the
binary parameters. When the disruption occurs before the star reaches the
innermost stable circular orbit, the gravitational wave (GW) signal emitted by
the system is expected to exhibit a cutoff frequency nu_GWtide, which is a
distinctive feature of the waveform. We evaluate nu_GWtide and show that, if
this frequency will be found in a detected gravitational wave, it will allow to
determine the neutron star radius with an error of a few percent, providing
valuable information on the behaviour of matter in the stellar core.
| [
{
"created": "Fri, 18 Dec 2009 14:51:53 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Mar 2010 17:03:21 GMT",
"version": "v2"
},
{
"created": "Tue, 16 Mar 2010 15:49:25 GMT",
"version": "v3"
}
] | 2010-04-14 | [
[
"Ferrari",
"V.",
""
],
[
"Gualtieri",
"L.",
""
],
[
"Pannarale",
"F.",
""
]
] | We study the tidal disruption of neutron stars in black hole-neutron star coalescing binaries. We calculate the critical orbital separation at which the star is disrupted by the black hole tidal field for several equations of state describing the matter inside the neutron star, and for a large set of the binary parameters. When the disruption occurs before the star reaches the innermost stable circular orbit, the gravitational wave (GW) signal emitted by the system is expected to exhibit a cutoff frequency nu_GWtide, which is a distinctive feature of the waveform. We evaluate nu_GWtide and show that, if this frequency will be found in a detected gravitational wave, it will allow to determine the neutron star radius with an error of a few percent, providing valuable information on the behaviour of matter in the stellar core. |
2201.08785 | Luana Michela Modafferi | Luana M. Modafferi, Joan Moragues, David Keitel, LIGO Scientific
Collaboration, Virgo Collaboration, KAGRA Collaboration | Search setup for long-duration transient gravitational waves from
glitching pulsars during LIGO-Virgo third observing run | 5 pages, submitted to Proceedings of TAUP 2021 | J. Phys.: Conf. Ser. 2156 (2022) 012079 | 10.1088/1742-6596/2156/1/012079 | LIGO-P2100376 | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | Pulsars are spinning neutron stars which emit an electromagnetic beam. We
expect pulsars to slowly decrease their rotational frequency. However, sudden
increases of the rotational frequency have been observed from different
pulsars. These events are called "glitches" and they are followed by a
relaxation phase with timescales from days to months. Gravitational wave (GW)
emission may follow these peculiar events. We give an overview of the setup for
an analysis of GW data from the Advanced LIGO and Virgo third observing run
(O3) arXiv:2112.10990 searching for transient GW signals lasting hours to
months after glitches in known pulsars. The search method consists of placing a
template grid in frequency-spindown space with fixed grid spacings. Then, for
each point we compute the transient F-statistic which is maximized over a set
of transient parameters like the duration and start time of the potential
signals. A threshold on the detection statistic is then set, and we search for
peaks over the parameter space for each candidate.
| [
{
"created": "Fri, 21 Jan 2022 17:04:07 GMT",
"version": "v1"
}
] | 2022-02-24 | [
[
"Modafferi",
"Luana M.",
""
],
[
"Moragues",
"Joan",
""
],
[
"Keitel",
"David",
""
],
[
"Collaboration",
"LIGO Scientific",
""
],
[
"Collaboration",
"Virgo",
""
],
[
"Collaboration",
"KAGRA",
""
]
] | Pulsars are spinning neutron stars which emit an electromagnetic beam. We expect pulsars to slowly decrease their rotational frequency. However, sudden increases of the rotational frequency have been observed from different pulsars. These events are called "glitches" and they are followed by a relaxation phase with timescales from days to months. Gravitational wave (GW) emission may follow these peculiar events. We give an overview of the setup for an analysis of GW data from the Advanced LIGO and Virgo third observing run (O3) arXiv:2112.10990 searching for transient GW signals lasting hours to months after glitches in known pulsars. The search method consists of placing a template grid in frequency-spindown space with fixed grid spacings. Then, for each point we compute the transient F-statistic which is maximized over a set of transient parameters like the duration and start time of the potential signals. A threshold on the detection statistic is then set, and we search for peaks over the parameter space for each candidate. |
gr-qc/0201051 | Thomas W. Baumgarte | A. M. Knapp, E. J. Walker and T. W. Baumgarte | Illustrating Stability Properties of Numerical Relativity in
Electrodynamics | 5 pages, 2 figures, to be published as Brief Report in Physical
Review D | Phys.Rev. D65 (2002) 064031 | 10.1103/PhysRevD.65.064031 | null | gr-qc astro-ph | null | We show that a reformulation of the ADM equations in general relativity,
which has dramatically improved the stability properties of numerical
implementations, has a direct analogue in classical electrodynamics. We
numerically integrate both the original and the revised versions of Maxwell's
equations, and show that their distinct numerical behavior reflects the
properties found in linearized general relativity. Our results shed further
light on the stability properties of general relativity, illustrate them in a
very transparent context, and may provide a useful framework for further
improvement of numerical schemes.
| [
{
"created": "Tue, 15 Jan 2002 19:53:24 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Knapp",
"A. M.",
""
],
[
"Walker",
"E. J.",
""
],
[
"Baumgarte",
"T. W.",
""
]
] | We show that a reformulation of the ADM equations in general relativity, which has dramatically improved the stability properties of numerical implementations, has a direct analogue in classical electrodynamics. We numerically integrate both the original and the revised versions of Maxwell's equations, and show that their distinct numerical behavior reflects the properties found in linearized general relativity. Our results shed further light on the stability properties of general relativity, illustrate them in a very transparent context, and may provide a useful framework for further improvement of numerical schemes. |
0906.0313 | Nicolas Yunes | Nicolas Yunes, K. G. Arun, Emanuele Berti, Clifford M. Will | Post-Circular Expansion of Eccentric Binary Inspirals: Fourier-Domain
Waveforms in the Stationary Phase Approximation | 24 pages, 9 figures, Replaced with version that matches published
version. Version 3 corrects a small typo in \xi_{5} in Eq. (C1) | Phys.Rev.D80:084001,2009 | 10.1103/PhysRevD.80.084001 | null | gr-qc astro-ph.CO astro-ph.GA astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We lay the foundations for the construction of analytic expressions for
Fourier-domain gravitational waveforms produced by eccentric, inspiraling
compact binaries in a post-circular or small-eccentricity approximation. The
time-dependent, "plus" and "cross" polarizations are expanded in Bessel
functions, which are then self-consistently re-expanded in a power series about
zero initial eccentricity to eighth order. The stationary phase approximation
is then employed to obtain explicit analytic expressions for the Fourier
transform of the post-circular expanded, time-domain signal. We exemplify this
framework by considering Newtonian-accurate waveforms, which in the
post-circular scheme give rise to higher harmonics of the orbital phase and
amplitude corrections both to the amplitude and the phase of the Fourier domain
waveform. Such higher harmonics lead to an effective increase in the inspiral
mass reach of a detector as a function of the binary's eccentricity e_0 at the
time when the binary enters the detector sensitivity band. Using the largest
initial eccentricity allowed by our approximations (e_0 < 0.4), the mass reach
is found to be enhanced up to factors of approximately 5 relative to that of
circular binaries for Advanced LIGO, LISA, and the proposed Einstein Telescope
at a signal-to-noise ratio of ten. A post-Newtonian generalization of the post
circular scheme is also discussed, which holds the promise to provide
"ready-to-use" Fourier-domain waveforms for data analysis of eccentric
inspirals.
| [
{
"created": "Mon, 1 Jun 2009 16:56:25 GMT",
"version": "v1"
},
{
"created": "Sat, 10 Oct 2009 19:29:36 GMT",
"version": "v2"
},
{
"created": "Wed, 14 May 2014 00:32:04 GMT",
"version": "v3"
}
] | 2014-05-15 | [
[
"Yunes",
"Nicolas",
""
],
[
"Arun",
"K. G.",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Will",
"Clifford M.",
""
]
] | We lay the foundations for the construction of analytic expressions for Fourier-domain gravitational waveforms produced by eccentric, inspiraling compact binaries in a post-circular or small-eccentricity approximation. The time-dependent, "plus" and "cross" polarizations are expanded in Bessel functions, which are then self-consistently re-expanded in a power series about zero initial eccentricity to eighth order. The stationary phase approximation is then employed to obtain explicit analytic expressions for the Fourier transform of the post-circular expanded, time-domain signal. We exemplify this framework by considering Newtonian-accurate waveforms, which in the post-circular scheme give rise to higher harmonics of the orbital phase and amplitude corrections both to the amplitude and the phase of the Fourier domain waveform. Such higher harmonics lead to an effective increase in the inspiral mass reach of a detector as a function of the binary's eccentricity e_0 at the time when the binary enters the detector sensitivity band. Using the largest initial eccentricity allowed by our approximations (e_0 < 0.4), the mass reach is found to be enhanced up to factors of approximately 5 relative to that of circular binaries for Advanced LIGO, LISA, and the proposed Einstein Telescope at a signal-to-noise ratio of ten. A post-Newtonian generalization of the post circular scheme is also discussed, which holds the promise to provide "ready-to-use" Fourier-domain waveforms for data analysis of eccentric inspirals. |
gr-qc/0703012 | Masayuki Tanimoto | Masayuki Tanimoto and Yasusada Nambu | Luminosity distance-redshift relation for the LTB solution near the
center | 18 pages, 2 figures, including 2 new paragraphs and 1 figure in
section 2, final version to appear in Classical and Quantum Gravity | Class.Quant.Grav.24:3843-3857,2007 | 10.1088/0264-9381/24/15/006 | null | gr-qc astro-ph | null | Motivated by the inverse problem for the Lemaitre-Tolman-Bondi dust solution,
in which problem the luminosity distance function $D_L(z)$ is taken as an input
to select a specific model, we compute the function $D_L(z)$ of the LTB
solution up to the third order of $z$. To perform the otherwise cumbersome
computation, we introduce a new convenient form of the LTB solution, in which
the solution is explicit and unified. With this form of the LTB solution we
obtain the luminosity distance function with the full generality. We in
particular find that the function exactly coincides with that of a homogeneous
and isotropic dust solution up to second order, if we demand that the solution
be regular at the center.
| [
{
"created": "Fri, 2 Mar 2007 11:04:16 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Jul 2007 18:39:38 GMT",
"version": "v2"
}
] | 2010-10-27 | [
[
"Tanimoto",
"Masayuki",
""
],
[
"Nambu",
"Yasusada",
""
]
] | Motivated by the inverse problem for the Lemaitre-Tolman-Bondi dust solution, in which problem the luminosity distance function $D_L(z)$ is taken as an input to select a specific model, we compute the function $D_L(z)$ of the LTB solution up to the third order of $z$. To perform the otherwise cumbersome computation, we introduce a new convenient form of the LTB solution, in which the solution is explicit and unified. With this form of the LTB solution we obtain the luminosity distance function with the full generality. We in particular find that the function exactly coincides with that of a homogeneous and isotropic dust solution up to second order, if we demand that the solution be regular at the center. |
2106.01773 | Karim Mosani | Karim Mosani, Dipanjan Dey, Pankaj S. Joshi, Gauranga C. Samanta,
Harikrishnan Menon, Vaishnavi D. Patel | On the visibility of singularities in general relativity and modified
gravity theories | 11 pages, 4 figures, accepted in classical and quantum gravity | null | 10.1088/1361-6382/acd97a | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We investigate the global causal structure of the end state of a spherically
symmetric marginally bound Lemaitre-Tolman-Bondi (LTB) \cite{Lemaitre, Tolman,
Bondi} collapsing cloud (which is well studied in general relativity) in the
framework of modified gravity having the generalized Lagrangian $R+\alpha R^2$
in the action. Here $R$ is the Ricci scalar, and $\alpha \geq 0$ is a constant.
By fixing the functional form of the metric components of the LTB spacetime,
using up the available degree of freedom, we realize that the matching surface
of the interior and the exterior metric are different for different values of
$\alpha$. This change in the matching surface can alter the causal property of
the first central singularity. We depict this by showing a numerical example.
Additionally, for a globally naked singularity to have physical relevance, a
congruence of null geodesics should escape from such singularity to be visible
to an asymptotic observer for an infinite time. For this to happen, the first
central singularity should be a nodal point. We here give a heuristic method to
show that this singularity is a nodal point by considering the above class of
theory of gravity, of which general relativity is a particular case.
| [
{
"created": "Thu, 3 Jun 2021 11:54:34 GMT",
"version": "v1"
},
{
"created": "Sat, 12 Nov 2022 08:38:26 GMT",
"version": "v2"
},
{
"created": "Mon, 29 May 2023 13:24:51 GMT",
"version": "v3"
}
] | 2023-07-12 | [
[
"Mosani",
"Karim",
""
],
[
"Dey",
"Dipanjan",
""
],
[
"Joshi",
"Pankaj S.",
""
],
[
"Samanta",
"Gauranga C.",
""
],
[
"Menon",
"Harikrishnan",
""
],
[
"Patel",
"Vaishnavi D.",
""
]
] | We investigate the global causal structure of the end state of a spherically symmetric marginally bound Lemaitre-Tolman-Bondi (LTB) \cite{Lemaitre, Tolman, Bondi} collapsing cloud (which is well studied in general relativity) in the framework of modified gravity having the generalized Lagrangian $R+\alpha R^2$ in the action. Here $R$ is the Ricci scalar, and $\alpha \geq 0$ is a constant. By fixing the functional form of the metric components of the LTB spacetime, using up the available degree of freedom, we realize that the matching surface of the interior and the exterior metric are different for different values of $\alpha$. This change in the matching surface can alter the causal property of the first central singularity. We depict this by showing a numerical example. Additionally, for a globally naked singularity to have physical relevance, a congruence of null geodesics should escape from such singularity to be visible to an asymptotic observer for an infinite time. For this to happen, the first central singularity should be a nodal point. We here give a heuristic method to show that this singularity is a nodal point by considering the above class of theory of gravity, of which general relativity is a particular case. |
gr-qc/0003033 | Masayuki Tanimoto | Masayuki Tanimoto (YITP, Kyoto University) | Locally U(1)*U(1) Symmetric Cosmological Models: Topology and Dynamics | 32 pages, 1 figure, LaTeX2e, revised Introduction slightly. To appear
in CQG | Class.Quant.Grav. 18 (2001) 479-507 | 10.1088/0264-9381/18/3/309 | YITP-00-13 | gr-qc | null | We show examples which reveal influences of spatial topologies to dynamics,
using a class of spatially {\it closed} inhomogeneous cosmological models. The
models, called the {\it locally U(1)$\times$U(1) symmetric models} (or the {\it
generalized Gowdy models}), are characterized by the existence of two commuting
spatial {\it local} Killing vectors. For systematic investigations we first
present a classification of possible spatial topologies in this class. We
stress the significance of the locally homogeneous limits (i.e., the Bianchi
types or the `geometric structures') of the models. In particular, we show a
method of reduction to the natural reduced manifold, and analyze the
equivalences at the reduced level of the models as dynamical models. Based on
these fundamentals, we examine the influence of spatial topologies on dynamics
by obtaining translation and reflection operators which commute with the
dynamical flow in the phase space.
| [
{
"created": "Wed, 8 Mar 2000 19:32:31 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jan 2001 14:05:14 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Tanimoto",
"Masayuki",
"",
"YITP, Kyoto University"
]
] | We show examples which reveal influences of spatial topologies to dynamics, using a class of spatially {\it closed} inhomogeneous cosmological models. The models, called the {\it locally U(1)$\times$U(1) symmetric models} (or the {\it generalized Gowdy models}), are characterized by the existence of two commuting spatial {\it local} Killing vectors. For systematic investigations we first present a classification of possible spatial topologies in this class. We stress the significance of the locally homogeneous limits (i.e., the Bianchi types or the `geometric structures') of the models. In particular, we show a method of reduction to the natural reduced manifold, and analyze the equivalences at the reduced level of the models as dynamical models. Based on these fundamentals, we examine the influence of spatial topologies on dynamics by obtaining translation and reflection operators which commute with the dynamical flow in the phase space. |
2004.10252 | Mauricio Bellini | Juan Ignacio Musmarra (IFIMAR - CONICET & UNMdP), Mauricio Bellini
(IFIMAR - CONICET & UNMdP) | Large scales space-time waves from inflation with time dependent
cosmological parameter | improved version | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the emission of large-scales wavelength space-time waves during the
inflationary expansion of the universe, produced by back-reaction effects. As
an example, we study an inflationary model with variable time scale, where the
scale factor of the universe grows as a power of time. The coarse-grained field
to describe space-time waves is defined by using the Levy distribution, on the
wavenumber space. The evolution for the norm of these waves on cosmological
scales is calculated, and it is shown that decreases with time.
| [
{
"created": "Tue, 21 Apr 2020 19:40:25 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Jun 2020 14:36:12 GMT",
"version": "v2"
}
] | 2020-06-12 | [
[
"Musmarra",
"Juan Ignacio",
"",
"IFIMAR - CONICET & UNMdP"
],
[
"Bellini",
"Mauricio",
"",
"IFIMAR - CONICET & UNMdP"
]
] | We study the emission of large-scales wavelength space-time waves during the inflationary expansion of the universe, produced by back-reaction effects. As an example, we study an inflationary model with variable time scale, where the scale factor of the universe grows as a power of time. The coarse-grained field to describe space-time waves is defined by using the Levy distribution, on the wavenumber space. The evolution for the norm of these waves on cosmological scales is calculated, and it is shown that decreases with time. |
2001.11094 | Gustavo Arciniega | Gustavo Arciniega, Luisa Jaime and Gabriella Piccinelli | Inflationary predictions of Geometric Inflation | 15 pages, 3 figures. Accepted version for publication in Physics
Letters B. References added | null | 10.1016/j.physletb.2020.135731 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the framework of gravitational models obtained from the Geometric
Inflation's proposal, where an infinite tower of curvature scalars are included
into the action, we compute the slow-roll parameters by the Hubble slow-roll
approach. We test the viability of such models as inflationary scenarios,
focusing on the tensor-to-scalar ratio, $r$, and spectral scalar index, $n_s$,
relation. We find that all models considered here produce inflation and, most
of them coincide, some better than others, with the marginalized 95$\%$ CL
region given by Planck's data collaboration.
| [
{
"created": "Wed, 29 Jan 2020 21:05:41 GMT",
"version": "v1"
},
{
"created": "Sat, 29 Aug 2020 05:34:24 GMT",
"version": "v2"
}
] | 2020-09-02 | [
[
"Arciniega",
"Gustavo",
""
],
[
"Jaime",
"Luisa",
""
],
[
"Piccinelli",
"Gabriella",
""
]
] | In the framework of gravitational models obtained from the Geometric Inflation's proposal, where an infinite tower of curvature scalars are included into the action, we compute the slow-roll parameters by the Hubble slow-roll approach. We test the viability of such models as inflationary scenarios, focusing on the tensor-to-scalar ratio, $r$, and spectral scalar index, $n_s$, relation. We find that all models considered here produce inflation and, most of them coincide, some better than others, with the marginalized 95$\%$ CL region given by Planck's data collaboration. |
gr-qc/0602013 | James B. Hartle | James B. Hartle (University of California, Santa Barbara) | Generalizing Quantum Mechanics for Quantum Spacetime | 31 pages, 4 figures, latex, contribution to the 23rd Solvay
Conference, The Quantum Structure of Space and Time, one reference added | The Quantum Structure of Space and Time: ed. by D. Gross, M.
Henneaux, and A. Sevrin (World Scientific, Singapore, 2007) | null | null | gr-qc hep-th quant-ph | null | Familiar textbook quantum mechanics assumes a fixed background spacetime to
define states on spacelike surfaces and their unitary evolution between them.
Quantum theory has changed as our conceptions of space and time have evolved.
But quantum mechanics needs to be generalized further for quantum gravity where
spacetime geometry is fluctuating and without definite value. This paper
reviews a fully four-dimensional, sum-over-histories, generalized quantum
mechanics of cosmological spacetime geometry. This generalization is
constructed within the framework of generalized quantum theory. This is a
minimal set of principles for quantum theory abstracted from the modern quantum
mechanics of closed systems, most generally the universe. In this
generalization, states of fields on spacelike surfaces and their unitary
evolution are emergent properties appropriate when spacetime geometry behaves
approximately classically. The principles of generalized quantum theory allow
for the further generalization that would be necessary were spacetime not
fundamental. Emergent spacetime phenomena are discussed in general and
illustrated with the example of the classical spacetime geometries with large
spacelike surfaces that emerge from the `no-boundary' wave function of the
universe. These must be Lorentzian with one, and only one, time direction. The
essay concludes by raising the question of whether quantum mechanics itself is
emergent.
| [
{
"created": "Thu, 2 Feb 2006 21:37:43 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Feb 2006 22:52:22 GMT",
"version": "v2"
}
] | 2008-06-09 | [
[
"Hartle",
"James B.",
"",
"University of California, Santa Barbara"
]
] | Familiar textbook quantum mechanics assumes a fixed background spacetime to define states on spacelike surfaces and their unitary evolution between them. Quantum theory has changed as our conceptions of space and time have evolved. But quantum mechanics needs to be generalized further for quantum gravity where spacetime geometry is fluctuating and without definite value. This paper reviews a fully four-dimensional, sum-over-histories, generalized quantum mechanics of cosmological spacetime geometry. This generalization is constructed within the framework of generalized quantum theory. This is a minimal set of principles for quantum theory abstracted from the modern quantum mechanics of closed systems, most generally the universe. In this generalization, states of fields on spacelike surfaces and their unitary evolution are emergent properties appropriate when spacetime geometry behaves approximately classically. The principles of generalized quantum theory allow for the further generalization that would be necessary were spacetime not fundamental. Emergent spacetime phenomena are discussed in general and illustrated with the example of the classical spacetime geometries with large spacelike surfaces that emerge from the `no-boundary' wave function of the universe. These must be Lorentzian with one, and only one, time direction. The essay concludes by raising the question of whether quantum mechanics itself is emergent. |
2004.03626 | Alexandre Toubiana | Alexandre Toubiana, Sylvain Marsat, Enrico Barausse, Stanislav Babak,
John Baker | Tests of general relativity with stellar-mass black hole binaries
observed by LISA | Update references | Phys. Rev. D 101, 104038 (2020) | 10.1103/PhysRevD.101.104038 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the observation of stellar-mass black holes binaries with the
Laser Interferometer Space Antenna (LISA). Preliminary results based on Fisher
information matrix analyses have suggested that gravitational waves from those
sources could be very sensitive to possible deviations from the theory of
general relativity and from the strong equivalence principle during the
low-frequency binary inspiral. We perform a full Markov Chain Monte Carlo
Bayesian analysis to quantify the sensitivity of these signals to two
phenomenological modifications of general relativity, namely a putative
gravitational dipole emission and a non-zero mass for the graviton, properly
accounting for the detector's response. Moreover, we consider a scenario where
those sources could be observed also with Earth-based detectors, which should
measure the coalescence time with precision better than $1 \ {\rm ms}$. This
constraint on the coalescence time further improves the bounds that we can set
on those phenomenological deviations from general relativity. We show that
tests of dipole radiation and the graviton's mass should improve respectively
by seven and half an order(s) of magnitude over current bounds. Finally, we
discuss under which conditions one may claim the detection of a modification to
general relativity.
| [
{
"created": "Tue, 7 Apr 2020 18:05:32 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Jun 2020 08:12:04 GMT",
"version": "v2"
},
{
"created": "Tue, 5 Jan 2021 19:09:08 GMT",
"version": "v3"
}
] | 2021-01-07 | [
[
"Toubiana",
"Alexandre",
""
],
[
"Marsat",
"Sylvain",
""
],
[
"Barausse",
"Enrico",
""
],
[
"Babak",
"Stanislav",
""
],
[
"Baker",
"John",
""
]
] | We consider the observation of stellar-mass black holes binaries with the Laser Interferometer Space Antenna (LISA). Preliminary results based on Fisher information matrix analyses have suggested that gravitational waves from those sources could be very sensitive to possible deviations from the theory of general relativity and from the strong equivalence principle during the low-frequency binary inspiral. We perform a full Markov Chain Monte Carlo Bayesian analysis to quantify the sensitivity of these signals to two phenomenological modifications of general relativity, namely a putative gravitational dipole emission and a non-zero mass for the graviton, properly accounting for the detector's response. Moreover, we consider a scenario where those sources could be observed also with Earth-based detectors, which should measure the coalescence time with precision better than $1 \ {\rm ms}$. This constraint on the coalescence time further improves the bounds that we can set on those phenomenological deviations from general relativity. We show that tests of dipole radiation and the graviton's mass should improve respectively by seven and half an order(s) of magnitude over current bounds. Finally, we discuss under which conditions one may claim the detection of a modification to general relativity. |
gr-qc/9209004 | null | Edward Malec and Niall \'O Murchadha | A Quasilocal Test of the Finiteness of the Universe | 4pages, plaintex | null | null | null | gr-qc astro-ph | null | The Cosmological Principle states that the universe is both homogeneous and
isotropic. This, alone, is not enough to specify the global geometry of the
spacetime. If we were able to measure both the Hubble constant and the energy
density we could determine whether the universe is open or closed.
Unfortunately, while some agreement exists on the value of the Hubble constant,
the question of the energy density seems quite intractable. This Letter
describes a possible way of avoiding this difficulty and shows that if one
could measure the rate at which light-rays emerging from a surface expand, one
might well be able to deduce whether the universe is closed.
| [
{
"created": "Fri, 11 Sep 1992 10:41:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Malec",
"Edward",
""
],
[
"Murchadha",
"Niall Ó",
""
]
] | The Cosmological Principle states that the universe is both homogeneous and isotropic. This, alone, is not enough to specify the global geometry of the spacetime. If we were able to measure both the Hubble constant and the energy density we could determine whether the universe is open or closed. Unfortunately, while some agreement exists on the value of the Hubble constant, the question of the energy density seems quite intractable. This Letter describes a possible way of avoiding this difficulty and shows that if one could measure the rate at which light-rays emerging from a surface expand, one might well be able to deduce whether the universe is closed. |
1104.4673 | Kaca Bradonjic | Ka\'ca Bradonji\'c | Quantum Gravity and the Correspondence Principle | Essay written for the Gravity Research Foundation 2011 Awards for
Essays on Gravitation | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Standard approaches to quantum gravity start with a pre-spacetime structure
and attempt, in accordance with Bohr's correspondence principle, to recover the
pseudo-Riemannian manifold in the low energy limit. These approaches assume
there is a smooth transition from quantum gravity to general relativity common
to successful quantum theories. However, as gravitational field, and hence
spacetime, cannot be considered in isolation from physical fields,
discontinuities in properties of physical fields, such as loss of mass at the
electroweak symmetry breaking scale, may result in change of spacetime
structure somewhere between the Planck scale and the scale where general
relativity holds true. As a result, the correct theory of quantum gravity may
not have general relativity as its low energy limit.
| [
{
"created": "Mon, 25 Apr 2011 03:26:58 GMT",
"version": "v1"
}
] | 2011-04-26 | [
[
"Bradonjić",
"Kaća",
""
]
] | Standard approaches to quantum gravity start with a pre-spacetime structure and attempt, in accordance with Bohr's correspondence principle, to recover the pseudo-Riemannian manifold in the low energy limit. These approaches assume there is a smooth transition from quantum gravity to general relativity common to successful quantum theories. However, as gravitational field, and hence spacetime, cannot be considered in isolation from physical fields, discontinuities in properties of physical fields, such as loss of mass at the electroweak symmetry breaking scale, may result in change of spacetime structure somewhere between the Planck scale and the scale where general relativity holds true. As a result, the correct theory of quantum gravity may not have general relativity as its low energy limit. |
1311.1379 | Letizia Sammut | Letizia Sammut, Christopher Messenger, Andrew Melatos, Benjamin J.
Owen | Implementation of the frequency-modulated sideband search method for
gravitational waves from low mass X-ray binaries | 20 pages, 5 figures | Phys. Rev. D 89, 043001 (2014) | 10.1103/PhysRevD.89.043001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe the practical implementation of the sideband search, a search for
periodic gravitational waves from neutron stars in binary systems. The orbital
motion of the source in its binary system causes frequency-modulation in the
combination of matched filters known as the $\mathcal{F}$-statistic. The
sideband search is based on the incoherent summation of these
frequency-modulated $\mathcal{F}$-statistic sidebands. It provides a new
detection statistic for sources in binary systems, called the
$\mathcal{C}$-statistic. The search is well suited to low-mass X-ray binaries,
the brightest of which, called Sco X-1, is an ideal target candidate. For
sources like Sco X-1, with well constrained orbital parameters, a slight
variation on the search is possible. The extra orbital information can be used
to approximately demodulate the data from the binary orbital motion in the
coherent stage, before incoherently summing the now reduced number of
sidebands. We investigate this approach and show that it improves the
sensitivity of the standard Sco X-1 directed sideband search. Prior information
on the neutron star inclination and gravitational wave polarization can also be
used to improve upper limit sensitivity. We estimate the sensitivity of a Sco
X-1 directed sideband search on 10 days of LIGO data and show that it can beat
previous upper limits in current LIGO data, with a possibility of constraining
theoretical upper limits using future advanced instruments.
| [
{
"created": "Wed, 6 Nov 2013 13:14:17 GMT",
"version": "v1"
}
] | 2014-12-02 | [
[
"Sammut",
"Letizia",
""
],
[
"Messenger",
"Christopher",
""
],
[
"Melatos",
"Andrew",
""
],
[
"Owen",
"Benjamin J.",
""
]
] | We describe the practical implementation of the sideband search, a search for periodic gravitational waves from neutron stars in binary systems. The orbital motion of the source in its binary system causes frequency-modulation in the combination of matched filters known as the $\mathcal{F}$-statistic. The sideband search is based on the incoherent summation of these frequency-modulated $\mathcal{F}$-statistic sidebands. It provides a new detection statistic for sources in binary systems, called the $\mathcal{C}$-statistic. The search is well suited to low-mass X-ray binaries, the brightest of which, called Sco X-1, is an ideal target candidate. For sources like Sco X-1, with well constrained orbital parameters, a slight variation on the search is possible. The extra orbital information can be used to approximately demodulate the data from the binary orbital motion in the coherent stage, before incoherently summing the now reduced number of sidebands. We investigate this approach and show that it improves the sensitivity of the standard Sco X-1 directed sideband search. Prior information on the neutron star inclination and gravitational wave polarization can also be used to improve upper limit sensitivity. We estimate the sensitivity of a Sco X-1 directed sideband search on 10 days of LIGO data and show that it can beat previous upper limits in current LIGO data, with a possibility of constraining theoretical upper limits using future advanced instruments. |
gr-qc/0211058 | G. S. Khadekar | G.S.Khadekar, K.S.Adhav and G.R.Ghate (Department of Mathematics,
Nagpur University, Nagpur and Amravati University) | Mass formulae for spherically symmetric stellar configurations in five
dimensional space-time | 5 pages Latex, No figure | Astrophys.Space Sci. 289 (2004) 95-101 | 10.1023/B:ASTR.0000009395.67257.97 | null | gr-qc | null | An expression is derived where the mass is connected to an integral over the
pressure of gravitating matter in the frame work of five dimensional(5D)
space-time.
| [
{
"created": "Fri, 15 Nov 2002 11:32:14 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Khadekar",
"G. S.",
"",
"Department of Mathematics,\n Nagpur University, Nagpur and Amravati University"
],
[
"Adhav",
"K. S.",
"",
"Department of Mathematics,\n Nagpur University, Nagpur and Amravati University"
],
[
"Ghate",
"G. R.",
"",
"Department of ... | An expression is derived where the mass is connected to an integral over the pressure of gravitating matter in the frame work of five dimensional(5D) space-time. |
gr-qc/9904036 | Holger Lyre | Holger Lyre | Gauges, Holes, and their `Connections' | 13 pages, "Fifth International Conference on the History and
Foundations of General Relativity", July 8-11, 1999, University of Notre
Dame, Notre Dame, Indiana | null | null | null | gr-qc quant-ph | null | The purpose of this paper is to present a generalized hole argument for gauge
field theories and their geometrical setting in terms of fiber bundles. The
generalized hole argument is motivated and extended from the spacetime hole
arguments which appear in spacetime theories based on differentiable manifolds
such as general relativity. Analogously, the generalized hole argument rules
out fiber bundle substantivalism and, thus, a relationalistic interpretation of
the geometry of fiber bundle spaces is favoured. Along the way, the concept of
gauge field theories will be analyzed via considering the gauge principle and
thereby hopefully clarifying certain terminological ambiguities.
| [
{
"created": "Thu, 15 Apr 1999 03:07:17 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Lyre",
"Holger",
""
]
] | The purpose of this paper is to present a generalized hole argument for gauge field theories and their geometrical setting in terms of fiber bundles. The generalized hole argument is motivated and extended from the spacetime hole arguments which appear in spacetime theories based on differentiable manifolds such as general relativity. Analogously, the generalized hole argument rules out fiber bundle substantivalism and, thus, a relationalistic interpretation of the geometry of fiber bundle spaces is favoured. Along the way, the concept of gauge field theories will be analyzed via considering the gauge principle and thereby hopefully clarifying certain terminological ambiguities. |
2008.13326 | Ronaldo Vieira Lobato | G. A. Carvalho, F. Rocha, H. O. Oliveira, R. V. Lobato | General approach to the Lagrangian ambiguity in $f(R, T)$ gravity | New section added with application to Cosmology. Matches the
published version | Eur. Phys. J. C (2021) 81:134 | 10.1140/epjc/s10052-021-08920-4 | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | The $f(R,T)$ gravity is a theory whose gravitational action depends
arbitrarily on the Ricci scalar, $R$, and the trace of the stress-energy
tensor, $T$; its field equations also depend on matter Lagrangian,
$\mathcal{L}_{m}$. In the modified theories of gravity where field equations
depend on Lagrangian, there is no uniqueness on the Lagrangian definition and
the dynamics of the gravitational and matter fields can be different depending
on the choice performed. In this work, we have eliminated the $\mathcal{L}_{m}$
dependence from $f(R,T)$ gravity field equations by generalizing the approach
of Moraes [Eur. Phys. J. C 79(8), 674 (2019)]. We also propose a general
approach where we argue that the trace of the energy-momentum tensor must be
considered an "unknown" variable of the field equations. The trace can only
depend on fundamental constants and few inputs from the standard model. Our
proposal resolves two limitations: first the energy-momentum tensor of the
$f(R,T)$ gravity is not the perfect fluid one; second, the Lagrangian is not
well-defined. As a test of our approach we applied it to the study of the
matter era in cosmology, and the theory can successfully describe a transition
between a decelerated Universe to an accelerated one without the need for dark
energy.
| [
{
"created": "Mon, 31 Aug 2020 02:33:47 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Feb 2021 19:58:25 GMT",
"version": "v2"
}
] | 2021-02-11 | [
[
"Carvalho",
"G. A.",
""
],
[
"Rocha",
"F.",
""
],
[
"Oliveira",
"H. O.",
""
],
[
"Lobato",
"R. V.",
""
]
] | The $f(R,T)$ gravity is a theory whose gravitational action depends arbitrarily on the Ricci scalar, $R$, and the trace of the stress-energy tensor, $T$; its field equations also depend on matter Lagrangian, $\mathcal{L}_{m}$. In the modified theories of gravity where field equations depend on Lagrangian, there is no uniqueness on the Lagrangian definition and the dynamics of the gravitational and matter fields can be different depending on the choice performed. In this work, we have eliminated the $\mathcal{L}_{m}$ dependence from $f(R,T)$ gravity field equations by generalizing the approach of Moraes [Eur. Phys. J. C 79(8), 674 (2019)]. We also propose a general approach where we argue that the trace of the energy-momentum tensor must be considered an "unknown" variable of the field equations. The trace can only depend on fundamental constants and few inputs from the standard model. Our proposal resolves two limitations: first the energy-momentum tensor of the $f(R,T)$ gravity is not the perfect fluid one; second, the Lagrangian is not well-defined. As a test of our approach we applied it to the study of the matter era in cosmology, and the theory can successfully describe a transition between a decelerated Universe to an accelerated one without the need for dark energy. |
gr-qc/9208003 | Ghosh | Tarun Souradeep | Generation of seed perturbations from Quantum Cosmology | Plain Tex 24 Pages | Astrophys.J.402:375-381,1993 | 10.1086/172141 | IUCAA-06-92 | gr-qc astro-ph | null | The origin of seed perturbations in the Universe is studied within the
framework of a specific minisuperspace model. It is shown that the `creation'
of the Universe as a result of a quantum transition from a flat empty spacetime
would lead to a flat FLRW (Friedmann Lema\^\i tre Robertson-Walker) Universe
with weak inhomogeneous perturbations at large wavelengths. The power spectrum
of these perturbations is found to be scale invariant at horizon crossing
(i.e., the Harrison-Zeldovich spectrum). It is also recognised that the seed
perturbations generated in our model would be generically of the isocurvature
kind.
| [
{
"created": "Tue, 11 Aug 1992 22:30:09 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Souradeep",
"Tarun",
""
]
] | The origin of seed perturbations in the Universe is studied within the framework of a specific minisuperspace model. It is shown that the `creation' of the Universe as a result of a quantum transition from a flat empty spacetime would lead to a flat FLRW (Friedmann Lema\^\i tre Robertson-Walker) Universe with weak inhomogeneous perturbations at large wavelengths. The power spectrum of these perturbations is found to be scale invariant at horizon crossing (i.e., the Harrison-Zeldovich spectrum). It is also recognised that the seed perturbations generated in our model would be generically of the isocurvature kind. |
gr-qc/9904070 | Marc Mars | Marc Mars | A spacetime characterization of the Kerr metric | 23 pages, No figures, LaTeX, to appear in Classical and Quantum
Gravity | Class.Quant.Grav. 16 (1999) 2507-2523 | 10.1088/0264-9381/16/7/323 | null | gr-qc | null | We obtain a characterization of the Kerr metric among stationary,
asymptotically flat, vacuum spacetimes, which extends the characterization in
terms of the Simon tensor (defined only in the manifold of trajectories) to the
whole spacetime. More precisely, we define a three index tensor on any
spacetime with a Killing field, which vanishes identically for Kerr and which
coincides in the strictly stationary region with the Simon tensor when
projected down into the manifold of trajectories. We prove that a stationary
asymptotically flat vacuum spacetime with vanishing spacetime Simon tensor is
locally isometric to Kerr. A geometrical interpretation of this
characterization in terms of the Weyl tensor is also given. Namely, a
stationary, asymptotically flat vacuum spacetime such that each principal null
direction of the Killing form is a repeated principal null direction of the
Weyl tensor is locally isometric to Kerr.
| [
{
"created": "Tue, 27 Apr 1999 14:56:33 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Mars",
"Marc",
""
]
] | We obtain a characterization of the Kerr metric among stationary, asymptotically flat, vacuum spacetimes, which extends the characterization in terms of the Simon tensor (defined only in the manifold of trajectories) to the whole spacetime. More precisely, we define a three index tensor on any spacetime with a Killing field, which vanishes identically for Kerr and which coincides in the strictly stationary region with the Simon tensor when projected down into the manifold of trajectories. We prove that a stationary asymptotically flat vacuum spacetime with vanishing spacetime Simon tensor is locally isometric to Kerr. A geometrical interpretation of this characterization in terms of the Weyl tensor is also given. Namely, a stationary, asymptotically flat vacuum spacetime such that each principal null direction of the Killing form is a repeated principal null direction of the Weyl tensor is locally isometric to Kerr. |
1612.06278 | Katharina Radermacher | Katharina Radermacher | Strong Cosmic Censorship in orthogonal Bianchi class B perfect fluids
and vacuum models | 88 pages, v2: changes following suggestions by referee, v3: minor
typos, layout changes | null | null | null | gr-qc math-ph math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Strong Cosmic Censorship conjecture states that for generic initial data
to Einstein's field equations, the maximal globally hyperbolic development is
inextendible. We prove this conjecture in the class of orthogonal Bianchi class
B perfect fluids and vacuum spacetimes, by showing that unboundedness of
certain curvature invariants such as the Kretschmann scalar is a generic
property. The only spacetimes where this scalar remains bounded exhibit local
rotational symmetry or are of plane wave equilibrium type.
We further investigate the qualitative behaviour of solutions towards the
initial singularity. To this end, we work in the expansion-normalised variables
introduced by Hewitt-Wainwright and show that a set of full measure, which is
also a countable intersection of open and dense sets in the state space, yields
convergence to a specific subarc of the Kasner parabola. We further give an
explicit construction enabling the translation between these variables and
geometric initial data to Einstein's equations.
| [
{
"created": "Mon, 19 Dec 2016 17:32:31 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Dec 2017 16:22:57 GMT",
"version": "v2"
},
{
"created": "Mon, 11 Dec 2017 21:32:00 GMT",
"version": "v3"
}
] | 2017-12-13 | [
[
"Radermacher",
"Katharina",
""
]
] | The Strong Cosmic Censorship conjecture states that for generic initial data to Einstein's field equations, the maximal globally hyperbolic development is inextendible. We prove this conjecture in the class of orthogonal Bianchi class B perfect fluids and vacuum spacetimes, by showing that unboundedness of certain curvature invariants such as the Kretschmann scalar is a generic property. The only spacetimes where this scalar remains bounded exhibit local rotational symmetry or are of plane wave equilibrium type. We further investigate the qualitative behaviour of solutions towards the initial singularity. To this end, we work in the expansion-normalised variables introduced by Hewitt-Wainwright and show that a set of full measure, which is also a countable intersection of open and dense sets in the state space, yields convergence to a specific subarc of the Kasner parabola. We further give an explicit construction enabling the translation between these variables and geometric initial data to Einstein's equations. |
1209.1373 | David Garfinkle | David Garfinkle | Matters of Gravity, The Newsletter of the Topical Group on Gravitation
of the American Physical Society, Volume 40, Fall 2012 | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | GGR News:
we hear that..., by David Garfinkle
100 years ago, by David Garfinkle
New publisher and new book, by Vesselin Petkov
Research Briefs:
Dark matter news, by Katie Freese
LARES satellite, by Richard Matzner
Conference reports:
Workshop on gravitational wave bursts, by Pablo Laguna
JoshFest, by Ed Glass
Electromagnetic and gravitational wave astronomy, by Sean McWilliams
Bits, branes, and black holes, by Ted Jacobson and Don Marolf
| [
{
"created": "Thu, 6 Sep 2012 19:07:51 GMT",
"version": "v1"
}
] | 2012-09-07 | [
[
"Garfinkle",
"David",
""
]
] | GGR News: we hear that..., by David Garfinkle 100 years ago, by David Garfinkle New publisher and new book, by Vesselin Petkov Research Briefs: Dark matter news, by Katie Freese LARES satellite, by Richard Matzner Conference reports: Workshop on gravitational wave bursts, by Pablo Laguna JoshFest, by Ed Glass Electromagnetic and gravitational wave astronomy, by Sean McWilliams Bits, branes, and black holes, by Ted Jacobson and Don Marolf |
0903.3991 | Serguei Krasnikov | S. Krasnikov | Even the Minkowski space is holed | Some clarifications are added on the relation of the counter-example
to Geroch's proposal | Phys.Rev.D79:124041,2009 | 10.1103/PhysRevD.79.124041 | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | To cure the lack of predictive power of general relativity Geroch proposed to
complete the theory with an additional postulate that only "hole-free"
spacetimes are permitted. I argue that this postulate is too strong -- it
prohibits even the Minkowski space.
| [
{
"created": "Tue, 24 Mar 2009 00:23:57 GMT",
"version": "v1"
},
{
"created": "Tue, 30 Jun 2009 16:32:44 GMT",
"version": "v2"
}
] | 2009-09-27 | [
[
"Krasnikov",
"S.",
""
]
] | To cure the lack of predictive power of general relativity Geroch proposed to complete the theory with an additional postulate that only "hole-free" spacetimes are permitted. I argue that this postulate is too strong -- it prohibits even the Minkowski space. |
gr-qc/0106055 | Irina Filimonova | A.A.Logunov and M.A.Mestvirishvili | The Causality Principle in the Field Theory of Gravitation | 12 pages, latex file | Theor.Math.Phys. 129 (2001) 1439-1445; Teor.Mat.Fiz. 129 (2001)
153-160 | null | IHEP 2001-16 | gr-qc | null | The causality principle for the Relativistic Theory of Gravitation (RTG) is
presented. It is a straightforward consequence of the RTG basic postulates. The
necessary conditions for physical solutions of the gravitational field
equations to be fulfilled are given.
| [
{
"created": "Sat, 16 Jun 2001 11:57:58 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Logunov",
"A. A.",
""
],
[
"Mestvirishvili",
"M. A.",
""
]
] | The causality principle for the Relativistic Theory of Gravitation (RTG) is presented. It is a straightforward consequence of the RTG basic postulates. The necessary conditions for physical solutions of the gravitational field equations to be fulfilled are given. |
2204.13122 | Shahar Hod | Shahar Hod | Nontrivial spatial behavior of the Gauss-Bonnet curvature invariant of
rapidly-rotating Kerr black holes | 18 pages | Physical Review D 105, 084013 (2022) | 10.1103/PhysRevD.105.084013 | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | The Gauss-Bonnet curvature invariant has attracted the attention of
physicists and mathematicians over the years. In particular, it has recently
been proved that black holes can support external matter configurations that
are non-minimally coupled to the Gauss-Bonnet invariant of the curved
spacetime. Motivated by this physically interesting behavior of black holes in
Einstein-Gauss-Bonnet theories, we present a detailed {\it analytical} study of
the physical and mathematical properties of the Gauss-Bonnet curvature
invariant ${\cal G}_{\text{Kerr}}(r,\cos\theta;a/M)$ of spinning Kerr black
holes in the spacetime region outside the horizon. Interestingly, we prove
that, for all spinning Kerr spacetimes in the physically allowed regime
$a/M\in[0,1]$, the spin-dependent maximum curvature of the Gauss-Bonnet
invariant is attained at the equator of the black-hole surface. Intriguingly,
we reveal that the location of the global minimum of the Gauss-Bonnet invariant
has a highly non-trivial functional dependence on the black-hole rotation
parameter: (i) For Kerr black holes in the dimensionless slow-rotation
$a/M<(a/M)^{-}_{\text{crit}}=1/2$ regime, the Gauss-Bonnet curvature invariant
attains its global minimum asymptotically at spatial infinity, (ii) for black
holes in the intermediate spin regime $1/2=(a/M)^{-}_{\text{crit}}\leq
a/M\leq(a/M)^{+}_{\text{crit}}=
\sqrt{\Big\{{{7+\sqrt{7}\cos\Big[3^{-1}\arctan\big(3\sqrt{3}\big)\Big]-
\sqrt{21}\sin\Big[3^{-1}\arctan\big(3\sqrt{3}\big)\Big]\Big\}}/12}}$, the
global minima are located at the black-hole poles, and (iii) Kerr black holes
in the super-critical regime $a/M>(a/M)^{+}_{\text{crit}}$ are characterized by
a non-trivial functional behavior of the Gauss-Bonnet curvature invariant along
the black-hole horizon with a spin-dependent polar angle for the global minimum
point.
| [
{
"created": "Wed, 27 Apr 2022 18:00:01 GMT",
"version": "v1"
}
] | 2022-05-04 | [
[
"Hod",
"Shahar",
""
]
] | The Gauss-Bonnet curvature invariant has attracted the attention of physicists and mathematicians over the years. In particular, it has recently been proved that black holes can support external matter configurations that are non-minimally coupled to the Gauss-Bonnet invariant of the curved spacetime. Motivated by this physically interesting behavior of black holes in Einstein-Gauss-Bonnet theories, we present a detailed {\it analytical} study of the physical and mathematical properties of the Gauss-Bonnet curvature invariant ${\cal G}_{\text{Kerr}}(r,\cos\theta;a/M)$ of spinning Kerr black holes in the spacetime region outside the horizon. Interestingly, we prove that, for all spinning Kerr spacetimes in the physically allowed regime $a/M\in[0,1]$, the spin-dependent maximum curvature of the Gauss-Bonnet invariant is attained at the equator of the black-hole surface. Intriguingly, we reveal that the location of the global minimum of the Gauss-Bonnet invariant has a highly non-trivial functional dependence on the black-hole rotation parameter: (i) For Kerr black holes in the dimensionless slow-rotation $a/M<(a/M)^{-}_{\text{crit}}=1/2$ regime, the Gauss-Bonnet curvature invariant attains its global minimum asymptotically at spatial infinity, (ii) for black holes in the intermediate spin regime $1/2=(a/M)^{-}_{\text{crit}}\leq a/M\leq(a/M)^{+}_{\text{crit}}= \sqrt{\Big\{{{7+\sqrt{7}\cos\Big[3^{-1}\arctan\big(3\sqrt{3}\big)\Big]- \sqrt{21}\sin\Big[3^{-1}\arctan\big(3\sqrt{3}\big)\Big]\Big\}}/12}}$, the global minima are located at the black-hole poles, and (iii) Kerr black holes in the super-critical regime $a/M>(a/M)^{+}_{\text{crit}}$ are characterized by a non-trivial functional behavior of the Gauss-Bonnet curvature invariant along the black-hole horizon with a spin-dependent polar angle for the global minimum point. |
gr-qc/0310066 | Pieter Blue | P. Blue, A. Soffer | The wave equation on the Schwarzschild metric II: Local decay for the
spin 2 Regge Wheeler equation | AMS-LaTeX, 8 pages with 1 figure. There is an errata to this paper at
gr-qc/0608073 | J.Math.Phys. 46 (2005) 012502 | 10.1063/1.1824211 | null | gr-qc math-ph math.AP math.MP | null | Odd-type spin 2 perturbations of Einstein's equation can be reduced to the
scalar Regge-Wheeler equation. We show that the weighted norms of solutions are
in L^2 of time and space. This result uses commutator methods and applies
uniformly to all relevant spherical harmonics.
| [
{
"created": "Tue, 14 Oct 2003 19:01:01 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Aug 2006 22:19:41 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Blue",
"P.",
""
],
[
"Soffer",
"A.",
""
]
] | Odd-type spin 2 perturbations of Einstein's equation can be reduced to the scalar Regge-Wheeler equation. We show that the weighted norms of solutions are in L^2 of time and space. This result uses commutator methods and applies uniformly to all relevant spherical harmonics. |
1405.5684 | Otakar Svitek | Petr Kaspar and Otakar Svitek | Averaging in cosmology based on Cartan scalars | 13 pages | Class. Quantum Grav. 31 (2014) 095012 | 10.1088/0264-9381/31/9/095012 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | We present a new approach for averaging in general relativity and cosmology.
After a short review of the theory originally taken from the equivalence
problem, we consider two ways how to deal with averaging based on Cartan
scalars. We apply the theory for two different LTB models. In the first one,
correlation term behaves as a positive cosmological constant, in the second
example leading correlation term behaves like spatial curvature. We also show
nontriviality of averaging for linearized monochromatic gravitational wave.
| [
{
"created": "Thu, 22 May 2014 09:37:34 GMT",
"version": "v1"
}
] | 2014-05-23 | [
[
"Kaspar",
"Petr",
""
],
[
"Svitek",
"Otakar",
""
]
] | We present a new approach for averaging in general relativity and cosmology. After a short review of the theory originally taken from the equivalence problem, we consider two ways how to deal with averaging based on Cartan scalars. We apply the theory for two different LTB models. In the first one, correlation term behaves as a positive cosmological constant, in the second example leading correlation term behaves like spatial curvature. We also show nontriviality of averaging for linearized monochromatic gravitational wave. |
0905.2541 | Luca Fabbri | Luca Fabbri | On the Principle of Equivalence | 8 pages | Contemporary Fundamental Physics, Dark Matter, page 49-56
(Dvoeglazov Editor, Nova Publishers, 2012) | null | UdeM-GPP-TH-09-180 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the Principle of Equivalence along with Weyl theorem to discuss
the interpretation of gravity as a geometric effect; we study what are the
restrictions on the connections that must be required for this geometrization
to occur in the most general case.
| [
{
"created": "Fri, 15 May 2009 12:53:19 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Jul 2009 08:32:56 GMT",
"version": "v2"
},
{
"created": "Tue, 3 May 2011 18:22:41 GMT",
"version": "v3"
},
{
"created": "Tue, 5 Jun 2012 12:14:52 GMT",
"version": "v4"
},
{
"crea... | 2012-07-27 | [
[
"Fabbri",
"Luca",
""
]
] | We consider the Principle of Equivalence along with Weyl theorem to discuss the interpretation of gravity as a geometric effect; we study what are the restrictions on the connections that must be required for this geometrization to occur in the most general case. |
1507.01753 | Ali \"Ovg\"un | I. Sakalli and A. \"Ovg\"un | Quantum Tunneling of Massive Spin-1 Particles From Non-stationary
Metrics | 8 pages, Accepted by Gen. Relativ. Gravit. (GRG) for publication | Gen. Relativ. Gravit. 48, 1 (2016) | 10.1007/s10714-015-1997-y | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We focus on the HR of massive vector (spin-1) particles tunneling from
Schwarzschild BH expressed in the Kruskal-Szekeres (KS) and dynamic Lemaitre
(DL) coordinates. Using the Proca equation (PE) together with the
Hamilton-Jacobi (HJ) and the WKB methods, we show that the tunneling rate, and
its consequence Hawking temperature are well recovered by the quantum tunneling
of the massive vector particles.
| [
{
"created": "Tue, 7 Jul 2015 11:16:07 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Nov 2015 11:46:43 GMT",
"version": "v2"
}
] | 2015-11-26 | [
[
"Sakalli",
"I.",
""
],
[
"Övgün",
"A.",
""
]
] | We focus on the HR of massive vector (spin-1) particles tunneling from Schwarzschild BH expressed in the Kruskal-Szekeres (KS) and dynamic Lemaitre (DL) coordinates. Using the Proca equation (PE) together with the Hamilton-Jacobi (HJ) and the WKB methods, we show that the tunneling rate, and its consequence Hawking temperature are well recovered by the quantum tunneling of the massive vector particles. |
1601.05688 | Jorge Pullin | Miguel Campiglia, Rodolfo Gambini, Javier Olmedo, Jorge Pullin | Quantum self-gravitating collapsing matter in a quantum geometry | 4 pages, RevTex | null | 10.1088/0264-9381/33/18/18LT01 | LSU-REL-012116 | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The problem of how space-time responds to gravitating quantum matter in full
quantum gravity has been one of the main questions that any program of
quantization of gravity should address. Here we analyze this issue by
considering the quantization of a collapsing null shell coupled to spherically
symmetric loop quantum gravity. We show that the constraint algebra of
canonical gravity is Abelian both classically and when quantized using loop
quantum gravity techniques. The Hamiltonian constraint is well defined and
suitable Dirac observables characterizing the problem were identified at the
quantum level. We can write the metric as a parameterized Dirac observable at
the quantum level and study the physics of the collapsing shell and black hole
formation. We show how the singularity inside the black hole is eliminated by
loop quantum gravity and how the shell can traverse it. The construction is
compatible with a scenario in which the shell tunnels into a baby universe
inside the black hole or one in which it could emerge through a white hole.
| [
{
"created": "Thu, 21 Jan 2016 15:57:52 GMT",
"version": "v1"
}
] | 2016-09-07 | [
[
"Campiglia",
"Miguel",
""
],
[
"Gambini",
"Rodolfo",
""
],
[
"Olmedo",
"Javier",
""
],
[
"Pullin",
"Jorge",
""
]
] | The problem of how space-time responds to gravitating quantum matter in full quantum gravity has been one of the main questions that any program of quantization of gravity should address. Here we analyze this issue by considering the quantization of a collapsing null shell coupled to spherically symmetric loop quantum gravity. We show that the constraint algebra of canonical gravity is Abelian both classically and when quantized using loop quantum gravity techniques. The Hamiltonian constraint is well defined and suitable Dirac observables characterizing the problem were identified at the quantum level. We can write the metric as a parameterized Dirac observable at the quantum level and study the physics of the collapsing shell and black hole formation. We show how the singularity inside the black hole is eliminated by loop quantum gravity and how the shell can traverse it. The construction is compatible with a scenario in which the shell tunnels into a baby universe inside the black hole or one in which it could emerge through a white hole. |
2101.01736 | M. Afif Ismail | Yi-Zen Chu, M. Afif Ismail, Yen-Wei Liu | Late time tails and nonlinear memories in asymptotically de Sitter
spacetimes | 37 pages, 4 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the propagation of a massless scalar wave in de Sitter spacetime
perturbed by an arbitrary central mass. By focusing on the late time limit,
this probes the portion of the scalar signal traveling inside the null cone.
Unlike in asymptotically flat spacetimes, the amplitude of the scalar field
detected by an observer at timelike infinity does not decay back to zero but
develops a spacetime constant shift - both at zeroth and first order in the
central mass M. This indicates that massless scalar field propagation in
asymptotically de Sitter spacetimes exhibits both linear and nonlinear
tail-induced memories. On the other hand, for sufficiently late retarded times,
the monopole portion of the scalar signal measured at null infinity is found to
be amplified relative to its timelike infinity counterpart, by its nonlinear
interactions with the gravitation field at first order in M.
| [
{
"created": "Tue, 5 Jan 2021 19:03:12 GMT",
"version": "v1"
},
{
"created": "Fri, 7 May 2021 20:00:12 GMT",
"version": "v2"
}
] | 2021-05-11 | [
[
"Chu",
"Yi-Zen",
""
],
[
"Ismail",
"M. Afif",
""
],
[
"Liu",
"Yen-Wei",
""
]
] | We study the propagation of a massless scalar wave in de Sitter spacetime perturbed by an arbitrary central mass. By focusing on the late time limit, this probes the portion of the scalar signal traveling inside the null cone. Unlike in asymptotically flat spacetimes, the amplitude of the scalar field detected by an observer at timelike infinity does not decay back to zero but develops a spacetime constant shift - both at zeroth and first order in the central mass M. This indicates that massless scalar field propagation in asymptotically de Sitter spacetimes exhibits both linear and nonlinear tail-induced memories. On the other hand, for sufficiently late retarded times, the monopole portion of the scalar signal measured at null infinity is found to be amplified relative to its timelike infinity counterpart, by its nonlinear interactions with the gravitation field at first order in M. |
gr-qc/0612039 | Remo Garattini | Remo Garattini | Multigravity and Space Time Foam | 6 pages. Talk given at IRGAC-2006 (Barcelona, July 11-15, 2006),
accepted for publication in Journal of Physics A and extended version of the
talk given at MG11, Berlin, 23-29 July, 2006 | J.Phys.A40:7055-7060,2007 | 10.1088/1751-8113/40/25/S61 | null | gr-qc hep-th | null | We consider a multigravity approach to spacetime foam. As an application we
give indications on the computation of the cosmological constant, considered as
an eigenvalue of a Sturm-Liouville problem. A variational approach with
Gaussian trial wave functionals is used as a method to study such a problem. We
approximate the equation to one loop in a Schwarzschild background and a zeta
function regularization is involved to handle with divergences. The
regularization is closely related to the subtraction procedure appearing in the
computation of Casimir energy in a curved background. A renormalization
procedure is introduced to remove the infinities together with a
renormalization group equation.
| [
{
"created": "Wed, 6 Dec 2006 18:24:03 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Garattini",
"Remo",
""
]
] | We consider a multigravity approach to spacetime foam. As an application we give indications on the computation of the cosmological constant, considered as an eigenvalue of a Sturm-Liouville problem. A variational approach with Gaussian trial wave functionals is used as a method to study such a problem. We approximate the equation to one loop in a Schwarzschild background and a zeta function regularization is involved to handle with divergences. The regularization is closely related to the subtraction procedure appearing in the computation of Casimir energy in a curved background. A renormalization procedure is introduced to remove the infinities together with a renormalization group equation. |
0907.4514 | Lorenzo Iorio | Lorenzo Iorio | The perihelion precession of Saturn, planet X/Nemesis and MOND | LaTex2e, 14 pages, no figures, no tables. Accepted by The Open
Astronomy Journal (TOAJ). Typos in eq. (17) and eq. (18) corrected | Open Astron.J.3: 1-6, 2010 | 10.2174/1874381101003010001 | null | gr-qc astro-ph.EP physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the retrograde perihelion precession of Saturn \Delta\dot\varpi,
recently estimated by different teams of astronomers by processing ranging data
from the Cassini spacecraft and amounting to some milliarcseconds per century,
can be explained in terms of a localized, distant body X, not yet directly
discovered. From the determination of its tidal parameter K = GM_X/r_X^3 as a
function of its ecliptic longitude \lambda_X and latitude \beta_X, we calculate
the distance at which X may exist for different values of its mass, ranging
from the size of Mars to that of the Sun. The minimum distance would occur for
X located perpendicularly to the ecliptic, while the maximum distance is for X
lying in the ecliptic. We find for rock-ice planets of the size of Mars and the
Earth that they would be at about 80-150 au, respectively, while a
Jupiter-sized gaseous giant would be at approximately 1 kau. A typical brown
dwarf would be located at about 4 kau, while an object with the mass of the Sun
would be at approximately 10 kau, so that it could not be Nemesis for which a
solar mass and a heliocentric distance of about 88 kau are predicted. If X was
directed towards a specific direction, i.e. that of the Galactic Center, it
would mimick the action of a recently proposed form of the External Field
Effect (EFE) in the framework of the MOdified Newtonian Dynamics (MOND).
| [
{
"created": "Mon, 27 Jul 2009 15:30:56 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Aug 2009 09:30:23 GMT",
"version": "v2"
},
{
"created": "Fri, 21 Aug 2009 14:54:56 GMT",
"version": "v3"
},
{
"created": "Tue, 1 Sep 2009 13:32:37 GMT",
"version": "v4"
},
{
"cre... | 2011-01-13 | [
[
"Iorio",
"Lorenzo",
""
]
] | We show that the retrograde perihelion precession of Saturn \Delta\dot\varpi, recently estimated by different teams of astronomers by processing ranging data from the Cassini spacecraft and amounting to some milliarcseconds per century, can be explained in terms of a localized, distant body X, not yet directly discovered. From the determination of its tidal parameter K = GM_X/r_X^3 as a function of its ecliptic longitude \lambda_X and latitude \beta_X, we calculate the distance at which X may exist for different values of its mass, ranging from the size of Mars to that of the Sun. The minimum distance would occur for X located perpendicularly to the ecliptic, while the maximum distance is for X lying in the ecliptic. We find for rock-ice planets of the size of Mars and the Earth that they would be at about 80-150 au, respectively, while a Jupiter-sized gaseous giant would be at approximately 1 kau. A typical brown dwarf would be located at about 4 kau, while an object with the mass of the Sun would be at approximately 10 kau, so that it could not be Nemesis for which a solar mass and a heliocentric distance of about 88 kau are predicted. If X was directed towards a specific direction, i.e. that of the Galactic Center, it would mimick the action of a recently proposed form of the External Field Effect (EFE) in the framework of the MOdified Newtonian Dynamics (MOND). |
1112.4395 | Mir Faizal | Mir Faizal | Multiverse in the Third Quantized Horava-Lifshits Theory of Gravity | 11 pages, 0 figures, accepted for publication in Mod. Phys. Lett. A | Mod. Phys. Lett. A27: 1250007, 2012 | 10.1142/S0217732312500071 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we analyze the third quantization of Horava-Lifshits theory of
gravity without detail balance. We show that the Wheeler-DeWitt equation for
Horava-Lifshits theory of gravity in minisuperspace approximation becomes the
equation for time-dependent harmonic oscillator. After interpreting the scaling
factor as the time, we are able to derive the third quantized wavefunction for
multiverse. We also show in third quantized formalism it is possible that the
universe can form from nothing. After we go on to analyze the effect of
introducing interactions in the Wheeler-DeWitt equation. We see how this model
of interacting universes can be used to explain baryogenesis with violation of
baryon number conservation in the multiverse. We also analyze how this model
can possibly explain the present value of the cosmological constant. Finally we
analyze the possibility of the multiverse being formed from perturbations
around a false vacuum and its decay to a true vacuum.
| [
{
"created": "Mon, 19 Dec 2011 16:30:09 GMT",
"version": "v1"
}
] | 2015-06-03 | [
[
"Faizal",
"Mir",
""
]
] | In this paper we analyze the third quantization of Horava-Lifshits theory of gravity without detail balance. We show that the Wheeler-DeWitt equation for Horava-Lifshits theory of gravity in minisuperspace approximation becomes the equation for time-dependent harmonic oscillator. After interpreting the scaling factor as the time, we are able to derive the third quantized wavefunction for multiverse. We also show in third quantized formalism it is possible that the universe can form from nothing. After we go on to analyze the effect of introducing interactions in the Wheeler-DeWitt equation. We see how this model of interacting universes can be used to explain baryogenesis with violation of baryon number conservation in the multiverse. We also analyze how this model can possibly explain the present value of the cosmological constant. Finally we analyze the possibility of the multiverse being formed from perturbations around a false vacuum and its decay to a true vacuum. |
1602.05020 | Clemens S\"amann | Jiri Podolsky, Clemens S\"amann, Roland Steinbauer, Robert Svarc | The global uniqueness and $C^1$-regularity of geodesics in expanding
impulsive gravitational waves | 24 pages, 2 figures | 2016 Class. Quantum Grav. 33 195010 | 10.1088/0264-9381/33/19/195010 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study geodesics in the complete family of expanding impulsive
gravitational waves propagating in spaces of constant curvature, that is
Minkowski, de Sitter and anti-de Sitter universes. Employing the continuous
form of the metric we rigorously prove existence and global uniqueness of
continuously differentiable geodesics (in the sense of Filippov) and study
their interaction with the impulsive wave. Thereby we justify the
"$C^1$-matching procedure" used in the literature to derive their explicit
form.
| [
{
"created": "Tue, 16 Feb 2016 13:57:13 GMT",
"version": "v1"
},
{
"created": "Sun, 16 Oct 2016 16:23:03 GMT",
"version": "v2"
}
] | 2016-10-18 | [
[
"Podolsky",
"Jiri",
""
],
[
"Sämann",
"Clemens",
""
],
[
"Steinbauer",
"Roland",
""
],
[
"Svarc",
"Robert",
""
]
] | We study geodesics in the complete family of expanding impulsive gravitational waves propagating in spaces of constant curvature, that is Minkowski, de Sitter and anti-de Sitter universes. Employing the continuous form of the metric we rigorously prove existence and global uniqueness of continuously differentiable geodesics (in the sense of Filippov) and study their interaction with the impulsive wave. Thereby we justify the "$C^1$-matching procedure" used in the literature to derive their explicit form. |
0802.0652 | Plyatsko Roman | Roman Plyatsko, Oleksandr Stefanyshyn | Mathisson Equations: Non-Oscillatory Solutions in a Schwarzschild Field | 11 pages, 3 figures | ActaPhys.Polon.B39:23,2008 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Mathisson equations under the Frenkel-Mathisson supplementary condition
are studied in a Schwarzschild field. The choice of solutions, which describe
the motions of the proper center of mass of a spinning test particle, is
discussed, and the calculation procedure for highly relativistic motions is
proposed. The very motions are important for astrophysics while investigating
possible effects of the gravitational spin-orbit interaction on the particle's
world line and trajectory.
| [
{
"created": "Tue, 5 Feb 2008 16:01:09 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Plyatsko",
"Roman",
""
],
[
"Stefanyshyn",
"Oleksandr",
""
]
] | The Mathisson equations under the Frenkel-Mathisson supplementary condition are studied in a Schwarzschild field. The choice of solutions, which describe the motions of the proper center of mass of a spinning test particle, is discussed, and the calculation procedure for highly relativistic motions is proposed. The very motions are important for astrophysics while investigating possible effects of the gravitational spin-orbit interaction on the particle's world line and trajectory. |
0811.0312 | Mikhail Smolyakov | Mikhail N. Smolyakov | Maximally symmetric spaces in Brans-Dicke theory and the cosmological
constant | 4 pages, LaTeX | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this note we discuss a toy model in which the value of the effective
cosmological constant is associated with a symmetry properties of the vacuum
background solution and defined by the model parameter associated with a scalar
field non-minimally coupled to gravity. Although the parameters in the model
seem to have unrealistic values to account for the present value of the
cosmological constant, the model demonstrates a possible alternative way it can
arise.
| [
{
"created": "Mon, 3 Nov 2008 14:56:19 GMT",
"version": "v1"
}
] | 2008-11-04 | [
[
"Smolyakov",
"Mikhail N.",
""
]
] | In this note we discuss a toy model in which the value of the effective cosmological constant is associated with a symmetry properties of the vacuum background solution and defined by the model parameter associated with a scalar field non-minimally coupled to gravity. Although the parameters in the model seem to have unrealistic values to account for the present value of the cosmological constant, the model demonstrates a possible alternative way it can arise. |
2108.00374 | Pardyumn Kumar Sahoo | Gaurav Gadbail, Simran Arora, P.K. Sahoo | Power-law cosmology in Weyl-type $f(Q,T)$ gravity | Revised version submitted EPJP | Eur. Phys. J. Plus 136, 1040 (2021) | 10.1140/epjp/s13360-021-02048-w | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | Gravity is attributed to the spacetime curvature in classical General
Relativity (GR). But, other equivalent formulation or representations of GR,
such as torsion or non-metricity have altered the perception. We consider the
Weyl-type $f(Q, T)$ gravity, where $Q$ represents the non-metricity and $T$ is
the trace of energy momentum temsor, in which the vector field $\omega_{\mu}$
determines the non-metricity $Q_{\mu \nu \alpha}$ of the spacetime. In this
work, we employ the well-motivated $f(Q, T)= \alpha Q+ \frac{\beta}{6k^{2}} T$,
where $\alpha$ and $\beta$ are the model parameters. Furthermore, we assume
that the universe is dominated by the pressure-free matter, i.e. the case of
dust ($p=0$). We obtain the solution of field equations similar to a power-law
in Hubble parameter $H(z)$. We investigate the cosmological implications of the
model by constraining the model parameter $\alpha$ and $\beta$ using the recent
57 points Hubble data and 1048 points Pantheon supernovae data. To study
various dark energy models, we use statefinder analysis to address the current
cosmic acceleration. We also observe the $Om$ diagnostic describing various
phases of the universe. Finally, it is seen that the solution which mimics the
power-law fits well with the Pantheon data better than the Hubble data.
| [
{
"created": "Sun, 1 Aug 2021 06:29:59 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Sep 2021 16:06:47 GMT",
"version": "v2"
}
] | 2021-10-20 | [
[
"Gadbail",
"Gaurav",
""
],
[
"Arora",
"Simran",
""
],
[
"Sahoo",
"P. K.",
""
]
] | Gravity is attributed to the spacetime curvature in classical General Relativity (GR). But, other equivalent formulation or representations of GR, such as torsion or non-metricity have altered the perception. We consider the Weyl-type $f(Q, T)$ gravity, where $Q$ represents the non-metricity and $T$ is the trace of energy momentum temsor, in which the vector field $\omega_{\mu}$ determines the non-metricity $Q_{\mu \nu \alpha}$ of the spacetime. In this work, we employ the well-motivated $f(Q, T)= \alpha Q+ \frac{\beta}{6k^{2}} T$, where $\alpha$ and $\beta$ are the model parameters. Furthermore, we assume that the universe is dominated by the pressure-free matter, i.e. the case of dust ($p=0$). We obtain the solution of field equations similar to a power-law in Hubble parameter $H(z)$. We investigate the cosmological implications of the model by constraining the model parameter $\alpha$ and $\beta$ using the recent 57 points Hubble data and 1048 points Pantheon supernovae data. To study various dark energy models, we use statefinder analysis to address the current cosmic acceleration. We also observe the $Om$ diagnostic describing various phases of the universe. Finally, it is seen that the solution which mimics the power-law fits well with the Pantheon data better than the Hubble data. |
1006.3672 | Luca Fabbri | Luca Fabbri | On geometric relativistic foundations of matter field equations and
plane wave solutions | 11 pages | Mod.Phys.Lett.A27, 1250028 (2012) | 10.1142/S0217732312500289 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we start from the geometric relativistic foundations to define
the basis upon which matter field theories are built, and their wave solutions
are investigated, finding that they display repulsive interactions able to
reproduce the exclusion principle in terms of its effects in a dynamical way,
then discussing possible consequences and problems.
| [
{
"created": "Fri, 18 Jun 2010 12:02:16 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Oct 2010 13:59:42 GMT",
"version": "v2"
},
{
"created": "Tue, 5 Jun 2012 12:18:00 GMT",
"version": "v3"
}
] | 2012-08-23 | [
[
"Fabbri",
"Luca",
""
]
] | In this paper, we start from the geometric relativistic foundations to define the basis upon which matter field theories are built, and their wave solutions are investigated, finding that they display repulsive interactions able to reproduce the exclusion principle in terms of its effects in a dynamical way, then discussing possible consequences and problems. |
gr-qc/9911026 | Grigori Volovik | G.E. Volovik | Vierbein walls in condensed matter | 4 pages, no figures | Pisma Zh.Eksp.Teor.Fiz. 70 (1999) 705-710; JETP Lett. 70 (1999)
711-716 | 10.1134/1.568251 | null | gr-qc cond-mat hep-ph | null | The effective field, which plays the part of the vierbein in general
relativity, can have topologically stable surfaces, vierbein domain walls,
where the effective contravariant metric is degenerate. We consider vierbein
walls separating domains with the flat space-time which are not causally
connected at the classical level. Possibility of the quantum mechanical
connection between the domains is discussed.
| [
{
"created": "Mon, 8 Nov 1999 16:53:16 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Volovik",
"G. E.",
""
]
] | The effective field, which plays the part of the vierbein in general relativity, can have topologically stable surfaces, vierbein domain walls, where the effective contravariant metric is degenerate. We consider vierbein walls separating domains with the flat space-time which are not causally connected at the classical level. Possibility of the quantum mechanical connection between the domains is discussed. |
1107.2520 | Daniele Nicolodi | A. Cavalleri, G. Ciani, R. Dolesi, A. Heptonstall, M. Hueller, D.
Nicolodi, S. Rowan, D. Tombolato, S. Vitale, P. J. Wass, and W. J. Weber | Increased Brownian force noise from molecular impacts in a constrained
volume | 4 pages, 5 figures | Phys. Rev. Lett. 103, 140601 (2009) | 10.1103/PhysRevLett.103.140601 | null | gr-qc physics.class-ph physics.ins-det | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We report on residual gas damping of the motion of a macroscopic test mass
enclosed in a nearby housing in the molecular flow regime. The damping
coefficient, and thus the associated thermal force noise, is found to increase
significantly when the distance between test mass and surrounding walls is
smaller than the test mass itself. The effect has been investigated with two
torsion pendulums of different geometry and has been modelled in a numerical
simulation whose predictions are in good agreement with the measurements.
Relevant to a wide variety of small-force experiments, the residual-gas force
noise power for the test masses in the LISA gravitational wave observatory is
roughly a factor 15 larger than in an infinite gas volume, though still
compatible with the target acceleration noise of 3 fm s^-2 Hz^-1/2 at the
foreseen pressure below 10^-6 Pa.
| [
{
"created": "Wed, 13 Jul 2011 10:57:09 GMT",
"version": "v1"
}
] | 2011-07-14 | [
[
"Cavalleri",
"A.",
""
],
[
"Ciani",
"G.",
""
],
[
"Dolesi",
"R.",
""
],
[
"Heptonstall",
"A.",
""
],
[
"Hueller",
"M.",
""
],
[
"Nicolodi",
"D.",
""
],
[
"Rowan",
"S.",
""
],
[
"Tombolato",
"D."... | We report on residual gas damping of the motion of a macroscopic test mass enclosed in a nearby housing in the molecular flow regime. The damping coefficient, and thus the associated thermal force noise, is found to increase significantly when the distance between test mass and surrounding walls is smaller than the test mass itself. The effect has been investigated with two torsion pendulums of different geometry and has been modelled in a numerical simulation whose predictions are in good agreement with the measurements. Relevant to a wide variety of small-force experiments, the residual-gas force noise power for the test masses in the LISA gravitational wave observatory is roughly a factor 15 larger than in an infinite gas volume, though still compatible with the target acceleration noise of 3 fm s^-2 Hz^-1/2 at the foreseen pressure below 10^-6 Pa. |
2003.03563 | Genly Le\'on | Genly Leon (Catolica del Norte U.), Esteban Gonz\'alez (Universidad de
Aconcagua, Chile), Alfredo D. Millano (Catolica del Norte U.), Felipe Orlando
Franz Silva | A Perturbative Analysis of Interacting Scalar Field Cosmologies | 47 pages, 31 compound figures. Reduced and improved version. The
analysis was redone and a new perspective was taken. New authors participated | null | null | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Scalar field cosmologies with a generalized harmonic potential are
investigated in flat and negatively curved
Friedmann-Lema\^itre-Robertson-Walker and Bianchi I metrics. An interaction
between the scalar field and matter is considered. Asymptotic methods and
averaging theory are used to obtain relevant information about the solution
space. In this approach, the Hubble parameter plays the role of a
time-dependent perturbation parameter which controls the magnitude of the error
between full-system and time-averaged solutions as it decreases. Our approach
is used to show that full and time-averaged systems have the same asymptotic
behavior. Numerical simulations are presented as evidence of such behavior.
Moreover, the asymptotic behavior of the solutions is independent of the
coupling function.
| [
{
"created": "Sat, 7 Mar 2020 11:53:05 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Nov 2020 18:13:44 GMT",
"version": "v2"
},
{
"created": "Sun, 16 Jan 2022 00:41:29 GMT",
"version": "v3"
}
] | 2022-01-19 | [
[
"Leon",
"Genly",
"",
"Catolica del Norte U."
],
[
"González",
"Esteban",
"",
"Universidad de\n Aconcagua, Chile"
],
[
"Millano",
"Alfredo D.",
"",
"Catolica del Norte U."
],
[
"Silva",
"Felipe Orlando Franz",
""
]
] | Scalar field cosmologies with a generalized harmonic potential are investigated in flat and negatively curved Friedmann-Lema\^itre-Robertson-Walker and Bianchi I metrics. An interaction between the scalar field and matter is considered. Asymptotic methods and averaging theory are used to obtain relevant information about the solution space. In this approach, the Hubble parameter plays the role of a time-dependent perturbation parameter which controls the magnitude of the error between full-system and time-averaged solutions as it decreases. Our approach is used to show that full and time-averaged systems have the same asymptotic behavior. Numerical simulations are presented as evidence of such behavior. Moreover, the asymptotic behavior of the solutions is independent of the coupling function. |
1410.6042 | Andrew Williamson | A. R. Williamson, C. Biwer, S. Fairhurst, I. W. Harry, E. Macdonald,
D. Macleod, V. Predoi | Improved methods for detecting gravitational waves associated with short
gamma-ray bursts | 13 pages, 6 figures | Phys. Rev. D 90, 122004 (2014) | 10.1103/PhysRevD.90.122004 | LIGO-P1400044 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the era of second generation ground-based gravitational wave detectors,
short gamma-ray bursts (GRBs) will be among the most promising astrophysical
events for joint electromagnetic and gravitational wave observation. A targeted
search for gravitational wave compact binary merger signals in coincidence with
short GRBs was developed and used to analyze data from the first generation
LIGO and Virgo instruments. In this paper, we present improvements to this
search that enhance our ability to detect gravitational wave counterparts to
short GRBs. Specifically, we introduce an improved method for estimating the
gravitational wave background to obtain the event significance required to make
detections; implement a method of tiling extended sky regions, as required when
searching for signals associated to poorly localized GRBs from Fermi Gamma-ray
Burst Monitor or the InterPlanetary Network; and incorporate astrophysical
knowledge about the beaming of GRB emission to restrict the search parameter
space. We describe the implementation of these enhancements and demonstrate how
they improve the ability to observe binary merger gravitational wave signals
associated with short GRBs.
| [
{
"created": "Wed, 22 Oct 2014 13:47:26 GMT",
"version": "v1"
}
] | 2014-12-31 | [
[
"Williamson",
"A. R.",
""
],
[
"Biwer",
"C.",
""
],
[
"Fairhurst",
"S.",
""
],
[
"Harry",
"I. W.",
""
],
[
"Macdonald",
"E.",
""
],
[
"Macleod",
"D.",
""
],
[
"Predoi",
"V.",
""
]
] | In the era of second generation ground-based gravitational wave detectors, short gamma-ray bursts (GRBs) will be among the most promising astrophysical events for joint electromagnetic and gravitational wave observation. A targeted search for gravitational wave compact binary merger signals in coincidence with short GRBs was developed and used to analyze data from the first generation LIGO and Virgo instruments. In this paper, we present improvements to this search that enhance our ability to detect gravitational wave counterparts to short GRBs. Specifically, we introduce an improved method for estimating the gravitational wave background to obtain the event significance required to make detections; implement a method of tiling extended sky regions, as required when searching for signals associated to poorly localized GRBs from Fermi Gamma-ray Burst Monitor or the InterPlanetary Network; and incorporate astrophysical knowledge about the beaming of GRB emission to restrict the search parameter space. We describe the implementation of these enhancements and demonstrate how they improve the ability to observe binary merger gravitational wave signals associated with short GRBs. |
2012.05847 | Joao Magueijo | Joao Magueijo (Imperial College) | The real Chern-Simons wave function | Version accepted for publication | Phys. Rev. D 104, 026002 (2021) | 10.1103/PhysRevD.104.026002 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We examine the status of the Chern-Simons (or Kodama) state from the point of
view of a formulation of gravity that uses only real connection and metric
variables and a real action. We may package the {\it real} connection variables
into the complex Self-Dual Ashtekar connection (and will do so to make contact
with previous work), but that operation is essentially cosmetic and can be
undone at any step or even bypassed altogether. The action will remain the
(real) Einstein-Cartan action, forgoing the addition of the usual Holst (or
Nieh-Yan) term with an imaginary coefficient. It is then found that the
constraints are solved by a modification of the Chern-Simons state which is a
pure phase (in the Lorentzian theory, we stress), the phase containing only the
fully gauge-invariant imaginary part of the Chern-Simons functional. Thus, the
state for the "real theory" is non-pathological with regards to the most
egregious criticisms facing its "non-real" cousin, solving the complex theory.
A straightforward modification of the real Chern-Simons state is also a
solution in quasi-topological theories based on the Euler invariant, for which
the cosmological constant, $\Lambda$, is dynamical. In that case it is enough
to shift the usual factor of $\Lambda$ in the wave function to the inside of
the spatial Chern-Simons integral. The trick only works for the quasi-Euler
theory with a critical coupling previously identified in the literature. It
does not apply to the quasi-Pontryagin theory.
| [
{
"created": "Thu, 10 Dec 2020 17:39:41 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Jun 2021 09:36:18 GMT",
"version": "v2"
}
] | 2021-07-07 | [
[
"Magueijo",
"Joao",
"",
"Imperial College"
]
] | We examine the status of the Chern-Simons (or Kodama) state from the point of view of a formulation of gravity that uses only real connection and metric variables and a real action. We may package the {\it real} connection variables into the complex Self-Dual Ashtekar connection (and will do so to make contact with previous work), but that operation is essentially cosmetic and can be undone at any step or even bypassed altogether. The action will remain the (real) Einstein-Cartan action, forgoing the addition of the usual Holst (or Nieh-Yan) term with an imaginary coefficient. It is then found that the constraints are solved by a modification of the Chern-Simons state which is a pure phase (in the Lorentzian theory, we stress), the phase containing only the fully gauge-invariant imaginary part of the Chern-Simons functional. Thus, the state for the "real theory" is non-pathological with regards to the most egregious criticisms facing its "non-real" cousin, solving the complex theory. A straightforward modification of the real Chern-Simons state is also a solution in quasi-topological theories based on the Euler invariant, for which the cosmological constant, $\Lambda$, is dynamical. In that case it is enough to shift the usual factor of $\Lambda$ in the wave function to the inside of the spatial Chern-Simons integral. The trick only works for the quasi-Euler theory with a critical coupling previously identified in the literature. It does not apply to the quasi-Pontryagin theory. |
2111.05341 | Wei-Xiang Feng | Wei-Xiang Feng | On the Dynamical Instability of Monatomic Fluid Spheres in
(N+1)-Dimensional Spacetime | 28 pages, 4 figures, 6 tables. Typos corrected; version accepted for
publication in the Special Issue of Astronomy: Feature Papers in the
Astronomical Sciences | Astronomy 2 (1), 22-46 (2023) | 10.3390/astronomy2010004 | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | In this note, I derive the Chandrasekhar instability of a fluid sphere in
($N$+1)-dimensional Schwarzschild-Tangherlini spacetime and take the
homogeneous (uniform energy density) solution for illustration. Qualitatively,
the effect of positive (negative) cosmological constant tends to destabilize
(stabilize) the sphere. In the absence of cosmological constant, the privileged
position of (3+1)-dimensional spacetime is manifest in its own right. As it is
the marginal dimensionality in which a monatomic ideal fluid sphere is stable
but not too stable to trigger the onset of gravitational collapse. Furthermore,
it is the unique dimensionality that can accommodate stable hydrostatic
equilibrium with positive cosmological constant. However, given the current
cosmological constant observed no stable configuration can be larger than
$10^{21}~{\rm M}_\odot$. On the other hand, in (2+1) dimensions it is too
stable either in the context of Newtonian Gravity (NG) or Einstein's General
Relativity (GR). In GR, the role of negative cosmological constant is crucial
not only to guarantee fluid equilibrium (decreasing monotonicity of pressure)
but also to have the Ba{\~n}ados-Teitelboim-Zanelli (BTZ) solution. Owing to
the negativeness of the cosmological constant, there is no unstable
configuration for a homogeneous fluid disk with mass $0<\mathcal{M}\leq0.5$ to
collapse into a naked singularity, which supports the Cosmic Censorship
Conjecture. However, the relativistic instability can be triggered for a
homogeneous disk with mass $0.5<\mathcal{M}\lesssim0.518$ under causal limit,
which implies that BTZ holes of mass $\mathcal{M}_{\rm BTZ}>0$ could emerge
from collapsing fluid disks under proper conditions. The implicit assumptions
and implications are also discussed.
| [
{
"created": "Tue, 9 Nov 2021 19:00:00 GMT",
"version": "v1"
},
{
"created": "Tue, 21 Dec 2021 19:00:00 GMT",
"version": "v2"
},
{
"created": "Thu, 15 Sep 2022 07:43:32 GMT",
"version": "v3"
},
{
"created": "Tue, 7 Mar 2023 15:52:10 GMT",
"version": "v4"
}
] | 2023-03-08 | [
[
"Feng",
"Wei-Xiang",
""
]
] | In this note, I derive the Chandrasekhar instability of a fluid sphere in ($N$+1)-dimensional Schwarzschild-Tangherlini spacetime and take the homogeneous (uniform energy density) solution for illustration. Qualitatively, the effect of positive (negative) cosmological constant tends to destabilize (stabilize) the sphere. In the absence of cosmological constant, the privileged position of (3+1)-dimensional spacetime is manifest in its own right. As it is the marginal dimensionality in which a monatomic ideal fluid sphere is stable but not too stable to trigger the onset of gravitational collapse. Furthermore, it is the unique dimensionality that can accommodate stable hydrostatic equilibrium with positive cosmological constant. However, given the current cosmological constant observed no stable configuration can be larger than $10^{21}~{\rm M}_\odot$. On the other hand, in (2+1) dimensions it is too stable either in the context of Newtonian Gravity (NG) or Einstein's General Relativity (GR). In GR, the role of negative cosmological constant is crucial not only to guarantee fluid equilibrium (decreasing monotonicity of pressure) but also to have the Ba{\~n}ados-Teitelboim-Zanelli (BTZ) solution. Owing to the negativeness of the cosmological constant, there is no unstable configuration for a homogeneous fluid disk with mass $0<\mathcal{M}\leq0.5$ to collapse into a naked singularity, which supports the Cosmic Censorship Conjecture. However, the relativistic instability can be triggered for a homogeneous disk with mass $0.5<\mathcal{M}\lesssim0.518$ under causal limit, which implies that BTZ holes of mass $\mathcal{M}_{\rm BTZ}>0$ could emerge from collapsing fluid disks under proper conditions. The implicit assumptions and implications are also discussed. |
2307.04060 | Yun Soo Myung | Yun Soo Myung | Double instability of Schwarzschild black holes in Einstein-Weyl-scalar
theory | 12 pages, 2 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the stability of Schwarzschild black hole in Einstein-Weyl-scalar
(EWS) theory with a quadratic scalar coupling to the Weyl term. Its linearized
theory admits the Lichnerowicz equation for Ricci tensor as well as scalar
equation. The linearized Ricci-tensor carries with a regular mass term
($m^2_2$), whereas the linearized scalar has a tachyonic mass term
($-1/m^2_2$). It turns out that the double instability of Schwarzschild black
hole in EWS theory is given by Gregory-Laflamme and tachyonic instabilities. In
the small mass regime of $m_2<0.876$, the Schwarzschild black hole becomes
unstable against Ricci-tensor perturbations, while tachyonic instability is
achieved for $m_2<1.174$. The former would provide a single branch of
scalarized black holes, whereas the latter would induce infinite branches of
scalarized black holes.
| [
{
"created": "Sat, 8 Jul 2023 23:39:16 GMT",
"version": "v1"
}
] | 2023-07-11 | [
[
"Myung",
"Yun Soo",
""
]
] | We study the stability of Schwarzschild black hole in Einstein-Weyl-scalar (EWS) theory with a quadratic scalar coupling to the Weyl term. Its linearized theory admits the Lichnerowicz equation for Ricci tensor as well as scalar equation. The linearized Ricci-tensor carries with a regular mass term ($m^2_2$), whereas the linearized scalar has a tachyonic mass term ($-1/m^2_2$). It turns out that the double instability of Schwarzschild black hole in EWS theory is given by Gregory-Laflamme and tachyonic instabilities. In the small mass regime of $m_2<0.876$, the Schwarzschild black hole becomes unstable against Ricci-tensor perturbations, while tachyonic instability is achieved for $m_2<1.174$. The former would provide a single branch of scalarized black holes, whereas the latter would induce infinite branches of scalarized black holes. |
gr-qc/0609082 | Boris Hikin L | Boris Hikin | Tensor Potential Description of Matter and Space, II Semi-guage and the
Law of Conservation | 9 pages | null | null | null | gr-qc | null | Considered a unified field theory approach describing matter and space
(metric tensor) by means of a 3-index tensor $P^{i}_{jk}$. It is shown that if
the Lagrangian has partial U(1) gauge (semi-gauge) of the type
$P^{i}_{jk}->P^{i}_{jk}+a \delta{^i_j} \phi{_{,k}}+b \delta{^i_k}
\phi{_{,j}}+cg_{jk}g^{mi} \phi{_{,m}}$ where a,b,c are constants, then the
Euler equations of motion contain the covariant low of conservation in the form
$J^{k}_{;k}=0$.
| [
{
"created": "Wed, 20 Sep 2006 15:11:35 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Hikin",
"Boris",
""
]
] | Considered a unified field theory approach describing matter and space (metric tensor) by means of a 3-index tensor $P^{i}_{jk}$. It is shown that if the Lagrangian has partial U(1) gauge (semi-gauge) of the type $P^{i}_{jk}->P^{i}_{jk}+a \delta{^i_j} \phi{_{,k}}+b \delta{^i_k} \phi{_{,j}}+cg_{jk}g^{mi} \phi{_{,m}}$ where a,b,c are constants, then the Euler equations of motion contain the covariant low of conservation in the form $J^{k}_{;k}=0$. |
gr-qc/9602001 | Jorge Pullin | Jorge Pullin | Matters of Gravity, Newsletter of the APS TGG on gravitation, number 7 | available in http://vishnu.nirvana.phys.psu.edu/mog.html | null | null | MOG-7 | gr-qc | null | Contents:
Editorial, J. Pullin
Report from the APS TGG, Beverly Berger
We hear that..., J. Pullin
LIGO project status, S. Whitcomb
General relativity survives another test, C. Will
Macroscopic deviations from Hawking radiation? L. Smolin
Event horizons and topological censorship, E. Seidel
Critical behavior in black hole collapse, J. Horne
Third Texas Workshop on 3D Numerical Relativity, P. Laguna
ICGC-95, M.A.H. MacCallum
The Josh Goldberg Symposium, P. Saulson
Summer school in Bad Honnef, H.-P. Nollert
Fifth Annual Midwest Relativity Conference, J. Romano
Volga-7 '95, A. Aminova, D. Brill.
| [
{
"created": "Thu, 1 Feb 1996 15:33:10 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Pullin",
"Jorge",
""
]
] | Contents: Editorial, J. Pullin Report from the APS TGG, Beverly Berger We hear that..., J. Pullin LIGO project status, S. Whitcomb General relativity survives another test, C. Will Macroscopic deviations from Hawking radiation? L. Smolin Event horizons and topological censorship, E. Seidel Critical behavior in black hole collapse, J. Horne Third Texas Workshop on 3D Numerical Relativity, P. Laguna ICGC-95, M.A.H. MacCallum The Josh Goldberg Symposium, P. Saulson Summer school in Bad Honnef, H.-P. Nollert Fifth Annual Midwest Relativity Conference, J. Romano Volga-7 '95, A. Aminova, D. Brill. |
1104.1661 | Jose Martinez-Morales L. | Jose L. Martinez-Morales | The semi classical cosmology approximation for a Friedman Robertson
Walker geometry coupled to a field | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The semi classical cosmology approximation for a Friedman Robertson Walker
geometry coupled to a field is considered. A power series of the field with
coefficients that depend on the radius of the geometry is proposed, and the
equations for the coefficients are solved.
| [
{
"created": "Fri, 8 Apr 2011 23:40:34 GMT",
"version": "v1"
}
] | 2011-04-12 | [
[
"Martinez-Morales",
"Jose L.",
""
]
] | The semi classical cosmology approximation for a Friedman Robertson Walker geometry coupled to a field is considered. A power series of the field with coefficients that depend on the radius of the geometry is proposed, and the equations for the coefficients are solved. |
gr-qc/0301107 | Reinhard Meinel | Gernot Neugebauer, Andreas Kleinw\"achter and Reinhard Meinel | Relativistically rotating dust | 18 pages, 11 figures | Helv.Phys.Acta 69:472,1996 | null | null | gr-qc | null | Dust configurations play an important role in astrophysics and are the
simplest models for rotating bodies. The physical properties of the
general--relativistic global solution for the rigidly rotating disk of dust,
which has been found recently as the solution of a boundary value problem, are
discussed.
| [
{
"created": "Mon, 27 Jan 2003 14:46:31 GMT",
"version": "v1"
}
] | 2010-12-23 | [
[
"Neugebauer",
"Gernot",
""
],
[
"Kleinwächter",
"Andreas",
""
],
[
"Meinel",
"Reinhard",
""
]
] | Dust configurations play an important role in astrophysics and are the simplest models for rotating bodies. The physical properties of the general--relativistic global solution for the rigidly rotating disk of dust, which has been found recently as the solution of a boundary value problem, are discussed. |
gr-qc/0512029 | Claudio Simeone | Marc Thibeault, Claudio Simeone, Ernesto F. Eiroa | Thin-shell wormholes in Einstein-Maxwell theory with a Gauss-Bonnet term | 13 pages, 6 figures; v2: minor changes and new references added.
Accepted for publication in General Relativity and Gravitation | Gen.Rel.Grav.38:1593-1608,2006 | 10.1007/s10714-006-0324-z | null | gr-qc hep-th | null | We study five dimensional thin-shell wormholes in Einstein-Maxwell theory
with a Gauss-Bonnet term. The linearized stability under radial perturbations
and the amount of exotic matter are analyzed as a function of the parameters of
the model. We find that the inclusion of the quadratic correction substantially
widens the range of possible stable configurations, and besides it allows for a
reduction of the exotic matter required to construct the wormholes.
| [
{
"created": "Mon, 5 Dec 2005 18:53:52 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Jul 2006 14:37:10 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Thibeault",
"Marc",
""
],
[
"Simeone",
"Claudio",
""
],
[
"Eiroa",
"Ernesto F.",
""
]
] | We study five dimensional thin-shell wormholes in Einstein-Maxwell theory with a Gauss-Bonnet term. The linearized stability under radial perturbations and the amount of exotic matter are analyzed as a function of the parameters of the model. We find that the inclusion of the quadratic correction substantially widens the range of possible stable configurations, and besides it allows for a reduction of the exotic matter required to construct the wormholes. |
1011.6024 | Michele Levi | Barak Kol, Michele Levi, Michael Smolkin | Comparing space+time decompositions in the post-Newtonian limit | 11 pages, 3 figures; v2: published | Class.Quant.Grav.28:145021,2011 | 10.1088/0264-9381/28/14/145021 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The relationship between the Arnowitt-Deser-Misner (ADM) field decomposition
and the non-relativistic gravitational (NRG) fields attracted considerable
interest recently. This paper compares the two, especially with respect to
computing the two-body post-Newtonian (PN) effective action within the
effective field theory (EFT) approach. Both are space+time decompositions and
hence do better than using the standard metric. However, ADM is essentially a
reduction over space whereas NRG is essentially a reduction over time. We use a
variant of ADM which is linearly equivalent to NRG and the two are identical at
order 1PN. We compare the two at order 2PN and find that ADM requires the
computation of an additional Feynman diagram. We argue that the computational
excess will further increase at higher orders.
| [
{
"created": "Sun, 28 Nov 2010 10:09:17 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Jun 2011 15:21:38 GMT",
"version": "v2"
}
] | 2011-08-19 | [
[
"Kol",
"Barak",
""
],
[
"Levi",
"Michele",
""
],
[
"Smolkin",
"Michael",
""
]
] | The relationship between the Arnowitt-Deser-Misner (ADM) field decomposition and the non-relativistic gravitational (NRG) fields attracted considerable interest recently. This paper compares the two, especially with respect to computing the two-body post-Newtonian (PN) effective action within the effective field theory (EFT) approach. Both are space+time decompositions and hence do better than using the standard metric. However, ADM is essentially a reduction over space whereas NRG is essentially a reduction over time. We use a variant of ADM which is linearly equivalent to NRG and the two are identical at order 1PN. We compare the two at order 2PN and find that ADM requires the computation of an additional Feynman diagram. We argue that the computational excess will further increase at higher orders. |
1412.2960 | Thomas B\"ackdahl | Lars Andersson, Thomas B\"ackdahl and Pieter Blue | A new tensorial conservation law for Maxwell fields on the Kerr
background | 7 pages | J. Differential Geom. 105, no. 2, 163--176 (2017) | null | null | gr-qc math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new, conserved, symmetric tensor field for a source-free Maxwell test field
on a four-dimensional spacetime with a conformal Killing-Yano tensor,
satisfying a certain compatibility condition, is introduced. In particular,
this construction works for the Kerr spacetime.
| [
{
"created": "Tue, 9 Dec 2014 14:02:33 GMT",
"version": "v1"
}
] | 2017-02-10 | [
[
"Andersson",
"Lars",
""
],
[
"Bäckdahl",
"Thomas",
""
],
[
"Blue",
"Pieter",
""
]
] | A new, conserved, symmetric tensor field for a source-free Maxwell test field on a four-dimensional spacetime with a conformal Killing-Yano tensor, satisfying a certain compatibility condition, is introduced. In particular, this construction works for the Kerr spacetime. |
1305.6688 | Myungseok Eune | Myungseok Eune and Wontae Kim | Emergent Friedmann equation from the evolution of cosmic space revisited | 8 pages, no figure, Version accepted for publication in PRD | Phys. Rev. D 88, 067303 (2013) | 10.1103/PhysRevD.88.067303 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Following the recent study on the emergent Friedmann equation from the
expansion of cosmic space for a flat universe, we apply this method to a
nonflat universe, and modify the evolution equation to lead to the Friedmann
equation. In order to maintain the same form with the original evolution
equation, we have to define the time-dependent Plank constant, which shows that
the spatial curvature of $k=0$ and $k=1$ is preferable to $k=-1$ since the
Plank constant of the nonflat open universe is divergent. Finally, we discuss
its physical consequences.
| [
{
"created": "Wed, 29 May 2013 04:25:18 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Sep 2013 06:22:52 GMT",
"version": "v2"
}
] | 2013-10-08 | [
[
"Eune",
"Myungseok",
""
],
[
"Kim",
"Wontae",
""
]
] | Following the recent study on the emergent Friedmann equation from the expansion of cosmic space for a flat universe, we apply this method to a nonflat universe, and modify the evolution equation to lead to the Friedmann equation. In order to maintain the same form with the original evolution equation, we have to define the time-dependent Plank constant, which shows that the spatial curvature of $k=0$ and $k=1$ is preferable to $k=-1$ since the Plank constant of the nonflat open universe is divergent. Finally, we discuss its physical consequences. |
2303.12457 | Jo\~ao Lu\'is Rosa | Jo\~ao Lu\'is Rosa, Sante Carloni | Junction conditions for LRS spacetimes in the $1+1+2$ covariant
formalism | 23 pages. Several additions with respect to previous version | Phys. Rev. D 109, 104037 (2024) | 10.1103/PhysRevD.109.104037 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use the distribution formalism to derive the complete set of junction
conditions for general Local Rotationally Symmetric (LRS) spacetimes in the
$1+1+2$ covariant formalism. We start by developing a parametric framework
encompassing timelike, spacelike, or null hypersurfaces. We then introduce the
distribution formalism in the $1+1+2$ framework and obtain the necessary
conditions to preserve the regularity of the $1+1+2$ equations at the
separation hypersurface. Using these results, we can deduce some general
prescriptions on the junction of LRS spacetimes and the properties of the shell
in the non-smooth cases. As examples of the application of the junction
conditions, we use this formalism to perform the matching necessary to obtain
well-known solutions, e.g., the Martinez thin-shell, the Schwarzschild
constant-density fluid star, and the Oppenheimer-Snyder collapse.
| [
{
"created": "Wed, 22 Mar 2023 11:06:36 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Feb 2024 12:29:46 GMT",
"version": "v2"
},
{
"created": "Thu, 4 Apr 2024 20:00:29 GMT",
"version": "v3"
}
] | 2024-05-14 | [
[
"Rosa",
"João Luís",
""
],
[
"Carloni",
"Sante",
""
]
] | We use the distribution formalism to derive the complete set of junction conditions for general Local Rotationally Symmetric (LRS) spacetimes in the $1+1+2$ covariant formalism. We start by developing a parametric framework encompassing timelike, spacelike, or null hypersurfaces. We then introduce the distribution formalism in the $1+1+2$ framework and obtain the necessary conditions to preserve the regularity of the $1+1+2$ equations at the separation hypersurface. Using these results, we can deduce some general prescriptions on the junction of LRS spacetimes and the properties of the shell in the non-smooth cases. As examples of the application of the junction conditions, we use this formalism to perform the matching necessary to obtain well-known solutions, e.g., the Martinez thin-shell, the Schwarzschild constant-density fluid star, and the Oppenheimer-Snyder collapse. |
2110.07335 | Antonio Gallerati | Giovanni Ummarino and Antonio Gallerati | Superconductor in static gravitational, electric and magnetic fields
with vortex lattice | 17 pages, 2 figures, 1 table (corrected figure scales) | Results in Physics 30 (2021) 104838 | 10.1016/j.rinp.2021.104838 | null | gr-qc cond-mat.supr-con hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We estimate the conjectured interaction between the Earth gravitational field
and a superconductor immersed in external, static electric and magnetic field.
The latter is close to the sample upper critical field and generates the
presence of a vortex lattice. The proposed interaction could lead to multiple,
measurable effects. First of all, a local affection of the gravitational field
inside the superconductor could take place. Second, a new component of a
generalized electric field parallel to the superconductor surface is generated
inside the sample. The analysis is performed by using the time-dependent
Ginzburg-Landau theory combined with the gravito-Maxwell formalism. This
approach leads us to analytic solutions of the problem, also providing the
average values of the generated fields and corrections inside the sample. We
will also study which are the physical parameters to optimize and, in turn, the
most suitable materials to maximize the effect.
| [
{
"created": "Thu, 14 Oct 2021 13:08:41 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Feb 2022 16:04:38 GMT",
"version": "v2"
}
] | 2022-02-04 | [
[
"Ummarino",
"Giovanni",
""
],
[
"Gallerati",
"Antonio",
""
]
] | We estimate the conjectured interaction between the Earth gravitational field and a superconductor immersed in external, static electric and magnetic field. The latter is close to the sample upper critical field and generates the presence of a vortex lattice. The proposed interaction could lead to multiple, measurable effects. First of all, a local affection of the gravitational field inside the superconductor could take place. Second, a new component of a generalized electric field parallel to the superconductor surface is generated inside the sample. The analysis is performed by using the time-dependent Ginzburg-Landau theory combined with the gravito-Maxwell formalism. This approach leads us to analytic solutions of the problem, also providing the average values of the generated fields and corrections inside the sample. We will also study which are the physical parameters to optimize and, in turn, the most suitable materials to maximize the effect. |
1907.05868 | Rong-Jia Yang | Yaoguang Zheng, Rong-Jia Yang | Entropy and Energy of Static Spherically Symmetric Black Hole in $f(R)$
theory | 10 pages, no picture | Universe 2020, 6, 47 | 10.3390/universe6030047 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the new horizon first law in $f(R)$ theory with general
spherically symmetric black hole. We derive the general formulas to computed
the entropy and energy of the black hole. For applications, some nontrivial
black hole solutions in some popular $f(R)$ theories are investigated, the
entropies and the energies of black holes in these models are first calculated.
| [
{
"created": "Thu, 11 Jul 2019 14:56:38 GMT",
"version": "v1"
},
{
"created": "Sun, 29 Dec 2019 14:13:24 GMT",
"version": "v2"
},
{
"created": "Mon, 30 Mar 2020 13:29:00 GMT",
"version": "v3"
}
] | 2020-03-31 | [
[
"Zheng",
"Yaoguang",
""
],
[
"Yang",
"Rong-Jia",
""
]
] | We consider the new horizon first law in $f(R)$ theory with general spherically symmetric black hole. We derive the general formulas to computed the entropy and energy of the black hole. For applications, some nontrivial black hole solutions in some popular $f(R)$ theories are investigated, the entropies and the energies of black holes in these models are first calculated. |
1005.3696 | Christoph Solveen | Christoph Solveen | Local Thermal Equilibrium in Quantum Field Theory on Flat and Curved
Spacetimes | 16 pages, some minor changes and clarifications; section 4 has been
shortened as some unnecessary constructions have been removed | Class.Quant.Grav.27:235002,2010 | 10.1088/0264-9381/27/23/235002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The existence of local thermal equilibrium (LTE) states for quantum field
theory in the sense of Buchholz, Ojima and Roos is discussed in a
model-independent setting. It is shown that for spaces of finitely many
independent thermal observables there always exist states which are in LTE in
any compact region of Minkowski spacetime. Furthermore, LTE states in curved
spacetime are discussed and it is observed that the original definition of LTE
on curved backgrounds given by Buchholz and Schlemmer needs to be modified.
Under an assumption related to certain unboundedness properties of the
pointlike thermal observables, existence of states which are in LTE at a given
point in curved spacetime is established. The assumption is discussed for the
sets of thermal observables for the free scalar field considered by Schlemmer
and Verch.
| [
{
"created": "Thu, 20 May 2010 13:43:04 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Nov 2010 09:51:51 GMT",
"version": "v2"
}
] | 2010-11-05 | [
[
"Solveen",
"Christoph",
""
]
] | The existence of local thermal equilibrium (LTE) states for quantum field theory in the sense of Buchholz, Ojima and Roos is discussed in a model-independent setting. It is shown that for spaces of finitely many independent thermal observables there always exist states which are in LTE in any compact region of Minkowski spacetime. Furthermore, LTE states in curved spacetime are discussed and it is observed that the original definition of LTE on curved backgrounds given by Buchholz and Schlemmer needs to be modified. Under an assumption related to certain unboundedness properties of the pointlike thermal observables, existence of states which are in LTE at a given point in curved spacetime is established. The assumption is discussed for the sets of thermal observables for the free scalar field considered by Schlemmer and Verch. |
1906.09405 | Andrzej Okolow | Andrzej Okolow | Does time always slow down as gravity increases? | 32 pages, 5 figures, LaTeX, minor changes, linguistic mistakes
corrected | Eur. J. Phys. 41 (2020) 023001 | 10.1088/1361-6404/ab60bb | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | We consider gravitational time dilation between stationary observers and
present examples, which contradict the statement that "time slows down as
gravity increases". We show furthermore that this statement cannot be true in
general, if strength of gravity is defined in an observer independent manner.
We provide also a pedagogical introduction to gravitational time dilation, and
discuss aspects of this phenomenon, which are often omitted in textbooks on
general relativity.
| [
{
"created": "Sat, 22 Jun 2019 07:33:33 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Aug 2019 14:29:09 GMT",
"version": "v2"
},
{
"created": "Mon, 24 Feb 2020 21:25:00 GMT",
"version": "v3"
},
{
"created": "Wed, 24 Feb 2021 15:19:11 GMT",
"version": "v4"
}
] | 2021-02-25 | [
[
"Okolow",
"Andrzej",
""
]
] | We consider gravitational time dilation between stationary observers and present examples, which contradict the statement that "time slows down as gravity increases". We show furthermore that this statement cannot be true in general, if strength of gravity is defined in an observer independent manner. We provide also a pedagogical introduction to gravitational time dilation, and discuss aspects of this phenomenon, which are often omitted in textbooks on general relativity. |
gr-qc/9610021 | Diego Torres | Diego F. Torres | Slow Roll Inflation in Non-Minimally Coupled Theories: Hyperextended
Gravity Approach | latex file, 12 pages, no figures | Phys.Lett. A225 (1997) 13-17 | 10.1016/S0375-9601(96)00835-3 | null | gr-qc | null | The slow roll approximation is studied for cosmological models in
Hyperextended Scalar-Tensor Theories of Gravity. A procedure to obtain slow
roll solutions in non-minimally coupled gravity is outlined and some examples
are provided. An integral condition over the functional form of the non-minimal
coupling is imposed in order to obtain intermediate inflationary behavior.
| [
{
"created": "Thu, 10 Oct 1996 12:26:19 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Torres",
"Diego F.",
""
]
] | The slow roll approximation is studied for cosmological models in Hyperextended Scalar-Tensor Theories of Gravity. A procedure to obtain slow roll solutions in non-minimally coupled gravity is outlined and some examples are provided. An integral condition over the functional form of the non-minimal coupling is imposed in order to obtain intermediate inflationary behavior. |
2406.11926 | Karan Jani | Shobhit Ranjan, Karan Jani, Alexander H. Nitz, Kelly
Holley-Bockelmann, Curt Cutler | A Tale of Two Black Holes: Multiband Gravitational-Wave Measurement of
Recoil Kicks | 11 pages, 4 figures, 2 tables | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | The non-linear dynamics of General Relativity leave their imprint on remnants
of black hole mergers in the form of a recoil ``kick''. The kick has profound
astrophysical implications across the black hole mass range from stellar to
super-massive. However, a robust measurement of the kick for generic binaries
from gravitational-wave observations has proved so far to be extremely
challenging. In this \emph{letter}, we demonstrate the prospects of measuring
black hole kicks through a multiband gravitational-wave network consisting of
space mission LISA, the current earth-based detector network and a
third-generation detector. For two distinct cases of remnant black hole kick
(68 km/s, 1006 km/s) emerging from near identical pre-merger configuration of
GW190521 -- the first confirmed intermediate-mass black hole -- we find that
the multiband network will recover with 90\% credible level the projection of
the kick vector relative to the orbital plane within tens of km/s accuracy.
Such precise measurement of the kick offer a new set of multi-messenger
follow-ups and unprecedented tests of astrophysical formation channels.
| [
{
"created": "Mon, 17 Jun 2024 08:36:51 GMT",
"version": "v1"
}
] | 2024-06-19 | [
[
"Ranjan",
"Shobhit",
""
],
[
"Jani",
"Karan",
""
],
[
"Nitz",
"Alexander H.",
""
],
[
"Holley-Bockelmann",
"Kelly",
""
],
[
"Cutler",
"Curt",
""
]
] | The non-linear dynamics of General Relativity leave their imprint on remnants of black hole mergers in the form of a recoil ``kick''. The kick has profound astrophysical implications across the black hole mass range from stellar to super-massive. However, a robust measurement of the kick for generic binaries from gravitational-wave observations has proved so far to be extremely challenging. In this \emph{letter}, we demonstrate the prospects of measuring black hole kicks through a multiband gravitational-wave network consisting of space mission LISA, the current earth-based detector network and a third-generation detector. For two distinct cases of remnant black hole kick (68 km/s, 1006 km/s) emerging from near identical pre-merger configuration of GW190521 -- the first confirmed intermediate-mass black hole -- we find that the multiband network will recover with 90\% credible level the projection of the kick vector relative to the orbital plane within tens of km/s accuracy. Such precise measurement of the kick offer a new set of multi-messenger follow-ups and unprecedented tests of astrophysical formation channels. |
2407.17006 | Mohammad Sami | Sayantan Choudhury, M. Sami | Large fluctuations and Primordial Black Holes | 322 pages, 80 figures, 7 tables, Invited Physics Reports review,
Dedicated to the memory of Alexei A. Starobinsky, Criticism and comments are
most welcome | null | null | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we review in detail different mechanisms of generation of
large primordial fluctuations and their implications for the production of
primordial black holes (PBHs) and scalar-induced secondary gravity waves
(SIGW), with the ultimate aim of understanding the impact of loop correction on
quantum correlations and the power spectrum. To accomplish the goal, we provide
a concise, comprehensive, but in depth review of conceptual and technical
details of the standard model of the universe, namely, causal structure and
inflation, quantization of primordial perturbations and field theoretic
techniques such as "in-in" formalism needed for the estimation of loop
correction to the power spectrum. We discuss at length the severe constraints
(no-go) on PBH production in single-field inflation imposed by appropriately
renormalized quantum loop corrections, computed while maintaining the validity
of the perturbation framework and assuming sufficient inflation to address the
causality problem. Thereafter, we discuss in detail the efforts to circumvent
the no-go result in Galileon inflation, multiple sharp transition (MST)-induced
inflation, and stochastic single field inflation using an effective field
theoretic (EFT) framework applicable to a variety of models. We provide a
thorough analysis of the Dynamical Renormalization Group (DRG) resummation
approach, adiabatic and late-time renormalization schemes, and their use in
producing solar and sub-solar mass PBHs. Additionally, we give a summary of how
scalar-induced gravitational waves (SIGWs) are produced in MST setups and
Galileon inflation.Finally, the PBH overproduction issue is thoroughly
discussed.
| [
{
"created": "Wed, 24 Jul 2024 05:06:33 GMT",
"version": "v1"
}
] | 2024-07-25 | [
[
"Choudhury",
"Sayantan",
""
],
[
"Sami",
"M.",
""
]
] | In this paper, we review in detail different mechanisms of generation of large primordial fluctuations and their implications for the production of primordial black holes (PBHs) and scalar-induced secondary gravity waves (SIGW), with the ultimate aim of understanding the impact of loop correction on quantum correlations and the power spectrum. To accomplish the goal, we provide a concise, comprehensive, but in depth review of conceptual and technical details of the standard model of the universe, namely, causal structure and inflation, quantization of primordial perturbations and field theoretic techniques such as "in-in" formalism needed for the estimation of loop correction to the power spectrum. We discuss at length the severe constraints (no-go) on PBH production in single-field inflation imposed by appropriately renormalized quantum loop corrections, computed while maintaining the validity of the perturbation framework and assuming sufficient inflation to address the causality problem. Thereafter, we discuss in detail the efforts to circumvent the no-go result in Galileon inflation, multiple sharp transition (MST)-induced inflation, and stochastic single field inflation using an effective field theoretic (EFT) framework applicable to a variety of models. We provide a thorough analysis of the Dynamical Renormalization Group (DRG) resummation approach, adiabatic and late-time renormalization schemes, and their use in producing solar and sub-solar mass PBHs. Additionally, we give a summary of how scalar-induced gravitational waves (SIGWs) are produced in MST setups and Galileon inflation.Finally, the PBH overproduction issue is thoroughly discussed. |
2202.09038 | RuiFeng Zheng | Ruifeng Zheng, Taotao Qiu | Can the Quantization of Black Hole be detected? | 9 pages, 4 figures | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | As a mysterious celestial body predicted by General Relativity, black holes
have been confirmed by observations in recent years. But there are still many
unknown properties waiting for us to discover, one of the famous problems is
the quantization of black holes. The quantization of black holes gives new
research significance to black holes, but the quantization of black holes is
difficult to prove. Here we propose a new method to verify the quantization of
black holes: Carnot cycle. Our results show that if the black holes have
quantized energy levels, the work W they impose to us via the Carnot cycle
should also be quantized. We indirectly verify the quantization of black holes
by detecting the quantization of W, and contrast it with the classic Carnot
cycle. In addition, we have also verified the correctness of the second law of
thermodynamics under the premise of considering the quantization of black
holes.
| [
{
"created": "Fri, 18 Feb 2022 06:15:14 GMT",
"version": "v1"
}
] | 2022-02-21 | [
[
"Zheng",
"Ruifeng",
""
],
[
"Qiu",
"Taotao",
""
]
] | As a mysterious celestial body predicted by General Relativity, black holes have been confirmed by observations in recent years. But there are still many unknown properties waiting for us to discover, one of the famous problems is the quantization of black holes. The quantization of black holes gives new research significance to black holes, but the quantization of black holes is difficult to prove. Here we propose a new method to verify the quantization of black holes: Carnot cycle. Our results show that if the black holes have quantized energy levels, the work W they impose to us via the Carnot cycle should also be quantized. We indirectly verify the quantization of black holes by detecting the quantization of W, and contrast it with the classic Carnot cycle. In addition, we have also verified the correctness of the second law of thermodynamics under the premise of considering the quantization of black holes. |
1903.03098 | Emmanuil Saridakis | Shin'ichi Nojiri, Sergei D. Odintsov, Emmanuel N. Saridakis | Modified cosmology from extended entropy with varying exponent | 10 pages, 2 figures, to appear in Eur.Phys.J. C | null | 10.1140/epjc/s10052-019-6740-5 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a modified cosmological scenario that arises from the application
of non-extensive thermodynamics with varying exponent. We extract the modified
Friedmann equations, which contain new terms quantified by the non-extensive
exponent, possessing standard $\Lambda$CDM cosmology as a subcase. Concerning
the universe evolution at late times we obtain an effective dark energy sector,
and we show that we can acquire the usual thermal history, with the successive
sequence of matter and dark-energy epochs, with the effective dark-energy
equation-of-state parameter being in the quintessence or in the phantom regime.
The interesting feature of the scenario is that the above behaviors can be
obtained even if the explicit cosmological constant is set to zero, namely they
arise purely from the extra terms. Additionally, we confront the model with
Supernovae type Ia and Hubble parameter observational data, and we show that
the agreement is very good. Concerning the early-time universe we obtain
inflationary de Sitter solutions, which are driven by an effective cosmological
constant that includes the new terms of non-extensive thermodynamics. This
effective screening can provide a description of both inflation and late-time
acceleration with the same parameter choices, which is a significant advantage.
| [
{
"created": "Thu, 7 Mar 2019 18:49:31 GMT",
"version": "v1"
}
] | 2019-03-27 | [
[
"Nojiri",
"Shin'ichi",
""
],
[
"Odintsov",
"Sergei D.",
""
],
[
"Saridakis",
"Emmanuel N.",
""
]
] | We present a modified cosmological scenario that arises from the application of non-extensive thermodynamics with varying exponent. We extract the modified Friedmann equations, which contain new terms quantified by the non-extensive exponent, possessing standard $\Lambda$CDM cosmology as a subcase. Concerning the universe evolution at late times we obtain an effective dark energy sector, and we show that we can acquire the usual thermal history, with the successive sequence of matter and dark-energy epochs, with the effective dark-energy equation-of-state parameter being in the quintessence or in the phantom regime. The interesting feature of the scenario is that the above behaviors can be obtained even if the explicit cosmological constant is set to zero, namely they arise purely from the extra terms. Additionally, we confront the model with Supernovae type Ia and Hubble parameter observational data, and we show that the agreement is very good. Concerning the early-time universe we obtain inflationary de Sitter solutions, which are driven by an effective cosmological constant that includes the new terms of non-extensive thermodynamics. This effective screening can provide a description of both inflation and late-time acceleration with the same parameter choices, which is a significant advantage. |
1006.5541 | Julian Berengut | G. H. Gossel, J. C. Berengut and V. V. Flambaum | Energy levels of a scalar particle in a static gravitational field close
to the black hole limit | 5 pages, 3 figures; minor text changes | Gen.Rel.Grav.43:2673-2683,2011 | 10.1007/s10714-011-1191-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The bound-state energy levels of a scalar particle in the gravitational field
of finite-sized objects with interiors described by the Florides and
Schwarzschild metrics are found. For these metrics, bound states with zero
energy (where the binding energy is equal to the mass of the scalar particle)
only exist when a singularity occurs in the metric. For the Florides metric
this singularity occurs in the black hole limit, while for the constant density
(Schwarzschild interior) metric it corresponds to infinite pressure at the
center. Moreover, the energy spectrum is shown to become quasi-continuous as
the metric becomes singular.
| [
{
"created": "Tue, 29 Jun 2010 08:40:58 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Jul 2010 05:53:34 GMT",
"version": "v2"
},
{
"created": "Wed, 17 Nov 2010 05:08:40 GMT",
"version": "v3"
}
] | 2011-09-28 | [
[
"Gossel",
"G. H.",
""
],
[
"Berengut",
"J. C.",
""
],
[
"Flambaum",
"V. V.",
""
]
] | The bound-state energy levels of a scalar particle in the gravitational field of finite-sized objects with interiors described by the Florides and Schwarzschild metrics are found. For these metrics, bound states with zero energy (where the binding energy is equal to the mass of the scalar particle) only exist when a singularity occurs in the metric. For the Florides metric this singularity occurs in the black hole limit, while for the constant density (Schwarzschild interior) metric it corresponds to infinite pressure at the center. Moreover, the energy spectrum is shown to become quasi-continuous as the metric becomes singular. |
gr-qc/0206014 | Sergiu Vacaru | Sergiu Vacaru | Horizons and Geodesics of Black Ellipsoids | Published variant in IJMPD with modifications in some formulas,
conclusions and new references | Int.J.Mod.Phys. D12 (2003) 479-494 | 10.1142/S021827180300272X | null | gr-qc astro-ph hep-th math-ph math.DG math.MP | null | We analyze the horizon and geodesic structure of a class of 4D off--diagonal
metrics with deformed spherical symmetries, which are exact solutions of the
vacuum Einstein equations with anholonomic variables. The maximal analytic
extension of the ellipsoid type metrics are constructed and the Penrose
diagrams are analyzed with respect to adapted frames. We prove that for small
deformations (small eccentricities) there are such metrics that the geodesic
behaviour is similar to the Schwarzcshild one. We conclude that some vacuum
static and stationary ellipsoid configurations may describe black ellipsoid
objects.
| [
{
"created": "Wed, 5 Jun 2002 20:00:06 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Aug 2002 13:30:37 GMT",
"version": "v2"
},
{
"created": "Mon, 21 Jul 2003 16:31:14 GMT",
"version": "v3"
}
] | 2009-11-07 | [
[
"Vacaru",
"Sergiu",
""
]
] | We analyze the horizon and geodesic structure of a class of 4D off--diagonal metrics with deformed spherical symmetries, which are exact solutions of the vacuum Einstein equations with anholonomic variables. The maximal analytic extension of the ellipsoid type metrics are constructed and the Penrose diagrams are analyzed with respect to adapted frames. We prove that for small deformations (small eccentricities) there are such metrics that the geodesic behaviour is similar to the Schwarzcshild one. We conclude that some vacuum static and stationary ellipsoid configurations may describe black ellipsoid objects. |
gr-qc/9802041 | Zloshchastiev Konstantin | Konstantin G. Zloshchastiev | Barotropic thin shells with linear EOS as models of stars and
circumstellar shells in general relativity | final version; ps-version of figure is available by email request to
zlosh@email.com | Int.J.Mod.Phys. D8 (1999) 549-555 | 10.1142/S0218271899000389 | null | gr-qc astro-ph | null | The spherically symmetric thin shells of the barotropic fluids with the
linear equation of state are considered within the frameworks of general
relativity. We study several aspects of the shells as completely relativistic
models of stars, first of all the neutron stars and white dwarfs, and
circumstellar shells. The exact equations of motion of the shells are obtained.
Also we calculate the parameters of the equilibrium configurations, including
the radii of static shells. Finally, we study the stability of the equilibrium
shells against radial perturbations.
| [
{
"created": "Tue, 17 Feb 1998 11:36:13 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Feb 1998 11:24:01 GMT",
"version": "v2"
},
{
"created": "Sun, 16 May 1999 19:02:11 GMT",
"version": "v3"
},
{
"created": "Fri, 3 Sep 1999 12:33:59 GMT",
"version": "v4"
}
] | 2009-10-31 | [
[
"Zloshchastiev",
"Konstantin G.",
""
]
] | The spherically symmetric thin shells of the barotropic fluids with the linear equation of state are considered within the frameworks of general relativity. We study several aspects of the shells as completely relativistic models of stars, first of all the neutron stars and white dwarfs, and circumstellar shells. The exact equations of motion of the shells are obtained. Also we calculate the parameters of the equilibrium configurations, including the radii of static shells. Finally, we study the stability of the equilibrium shells against radial perturbations. |
2303.12690 | Cameron Bunney | Cameron R. D. Bunney and Jorma Louko | Circular motion analogue Unruh effect in a $2+1$ thermal bath: Robbing
from the rich and giving to the poor | 24 pages, 5 figures. v2: references added, typos corrected. v3:
references added, section 2 expanded after referee comments, typos corrected | Class. Quantum Grav. 40 155001 (2023) | 10.1088/1361-6382/acde3b | null | gr-qc cond-mat.quant-gas hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Unruh effect states that a uniformly linearly accelerated observer with
proper acceleration $a$ experiences the Minkowski vacuum as a thermal state at
temperature $T_U=a/(2\pi)$. An observer in uniform circular motion experiences
a similar effective temperature, operationally defined in terms of excitation
and de-excitation rates, and physically interpretable in terms of synchrotron
radiation, but this effective temperature depends not just on the acceleration
but also on the orbital speed and the excitation energy. In this paper we
consider an observer in uniform circular motion when the Minkowski vacuum is
replaced by an ambient thermal bath, and we address the interplay of ambient
temperature, Doppler effect, acceleration, and excitation energy. Specifically,
we consider a massless scalar field in $2 + 1$ spacetime dimensions, probed by
an Unruh-DeWitt detector, in a Minkowski (rather than proper) time formulation:
this setting describes proposed analogue spacetime systems in which the effect
may become experimentally testable, and in which an ambient temperature will
necessarily be present. We establish analytic results for the observer's
effective temperature in several asymptotic regions of the parameter space and
provide numerical results in the interpolating regions, finding that an
acceleration effect can be identified even when the Doppler effect dominates
the overall magnitude of the response. We also identify parameter regimes where
the observer sees a temperature lower than the ambient temperature,
experiencing a cooling Unruh effect.
| [
{
"created": "Wed, 22 Mar 2023 16:37:40 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Mar 2023 09:05:02 GMT",
"version": "v2"
},
{
"created": "Wed, 28 Jun 2023 13:45:59 GMT",
"version": "v3"
}
] | 2023-06-29 | [
[
"Bunney",
"Cameron R. D.",
""
],
[
"Louko",
"Jorma",
""
]
] | The Unruh effect states that a uniformly linearly accelerated observer with proper acceleration $a$ experiences the Minkowski vacuum as a thermal state at temperature $T_U=a/(2\pi)$. An observer in uniform circular motion experiences a similar effective temperature, operationally defined in terms of excitation and de-excitation rates, and physically interpretable in terms of synchrotron radiation, but this effective temperature depends not just on the acceleration but also on the orbital speed and the excitation energy. In this paper we consider an observer in uniform circular motion when the Minkowski vacuum is replaced by an ambient thermal bath, and we address the interplay of ambient temperature, Doppler effect, acceleration, and excitation energy. Specifically, we consider a massless scalar field in $2 + 1$ spacetime dimensions, probed by an Unruh-DeWitt detector, in a Minkowski (rather than proper) time formulation: this setting describes proposed analogue spacetime systems in which the effect may become experimentally testable, and in which an ambient temperature will necessarily be present. We establish analytic results for the observer's effective temperature in several asymptotic regions of the parameter space and provide numerical results in the interpolating regions, finding that an acceleration effect can be identified even when the Doppler effect dominates the overall magnitude of the response. We also identify parameter regimes where the observer sees a temperature lower than the ambient temperature, experiencing a cooling Unruh effect. |
1609.00811 | Sergey Cherkas L | S. L. Cherkas, V.L. Kalashnikov | Theory of gravity admitting arbitrary choice of the energy density
reference level | 16 pages, 4 figures | Proc. Natl. Acad. Sci. Belarus, Ser. Phys.-Math. 55, 83-96 (2019) | 10.29235/1561-2430-2019-55-1-83-96 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Five-vectors theory of gravity is proposed, which admits an arbitrary choice
of the energy density reference level. This theory is formulated as the
constraint theory, where the Lagrange multipliers turn out to be restricted to
some class of vector fields unlike the General Relativity (GR), where they are
arbitrary. The possible cosmological implication of the model proposed is that
the residual vacuum fluctuations dominate during the whole evolution of the
universe. That resembles the universe having a nearly linear dependence of
scale factor on cosmic time.
| [
{
"created": "Sat, 3 Sep 2016 10:19:33 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Oct 2016 09:15:56 GMT",
"version": "v2"
},
{
"created": "Thu, 27 Oct 2016 10:23:32 GMT",
"version": "v3"
},
{
"created": "Mon, 10 Jul 2017 07:32:36 GMT",
"version": "v4"
},
{
"cr... | 2019-04-02 | [
[
"Cherkas",
"S. L.",
""
],
[
"Kalashnikov",
"V. L.",
""
]
] | Five-vectors theory of gravity is proposed, which admits an arbitrary choice of the energy density reference level. This theory is formulated as the constraint theory, where the Lagrange multipliers turn out to be restricted to some class of vector fields unlike the General Relativity (GR), where they are arbitrary. The possible cosmological implication of the model proposed is that the residual vacuum fluctuations dominate during the whole evolution of the universe. That resembles the universe having a nearly linear dependence of scale factor on cosmic time. |
0811.2322 | Bin Wang | Xi He, Bin Wang, Songbai Chen | Quasinormal modes of charged squashed Kaluza-Klein black holes in the
G\"{o}del Universe | 11 pages, 4 figures, revised version, accepted for publication in PRD | Phys.Rev.D79:084005,2009 | 10.1103/PhysRevD.79.084005 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the quasinormal modes of scalar perturbation in the background of
five-dimensional charged Kaluza-Klein black holes with squashed horizons
immersed in the G\"{o}del universe. Besides the influence due to the
compactness of the extra dimension, we disclose the cosmological rotational
effect in the wave dynamics. The wave behavior affected by the G\"{o}del
parameter provides an interesting insight into the G\"{o}del universe.
| [
{
"created": "Fri, 14 Nov 2008 11:49:04 GMT",
"version": "v1"
},
{
"created": "Sun, 22 Mar 2009 09:27:10 GMT",
"version": "v2"
}
] | 2009-04-22 | [
[
"He",
"Xi",
""
],
[
"Wang",
"Bin",
""
],
[
"Chen",
"Songbai",
""
]
] | We study the quasinormal modes of scalar perturbation in the background of five-dimensional charged Kaluza-Klein black holes with squashed horizons immersed in the G\"{o}del universe. Besides the influence due to the compactness of the extra dimension, we disclose the cosmological rotational effect in the wave dynamics. The wave behavior affected by the G\"{o}del parameter provides an interesting insight into the G\"{o}del universe. |
gr-qc/0403094 | Christophe Le Poncin-Lafitte | Christophe Le Poncin-Lafitte, Bernard Linet and Pierre Teyssandier | World function and time transfer: general post-Minkowskian expansions | Introduction is rewritten ; 2 references are added. 22 pages, no
figure | Class.Quant.Grav. 21 (2004) 4463-4484 | 10.1088/0264-9381/21/18/012 | null | gr-qc astro-ph | null | In suitably chosen domains of space-time, the world function may be a
powerful tool for modelling the deflection of light and the time/frequency
transfer. In this paper we work out a recursive procedure for expanding the
world function into a perturbative series of ascending powers of the Newtonian
gravitational constant G. We show rigorously that each perturbation term is
given by a line integral taken along the unperturbed geodesic between two
points. Once the world function is known, it becomes possible to determine the
time transfer functions giving the propagation time of a photon between its
emission and its reception. We establish that the direction of a light ray as
measured in the 3-space relative to a given observer can be derived from these
time transfer functions, even if the metric is not stationary. We show how to
deduce these functions up to any given order in G from the perturbative
expansion of the world function. To illustrate the method, we carry out the
calculation of the world function and of the time transfer function outside a
static, spherically symmetric body up to the order G^2, the metric containing
three arbitrary parameters.
| [
{
"created": "Tue, 23 Mar 2004 13:37:01 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Aug 2004 14:41:32 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Poncin-Lafitte",
"Christophe Le",
""
],
[
"Linet",
"Bernard",
""
],
[
"Teyssandier",
"Pierre",
""
]
] | In suitably chosen domains of space-time, the world function may be a powerful tool for modelling the deflection of light and the time/frequency transfer. In this paper we work out a recursive procedure for expanding the world function into a perturbative series of ascending powers of the Newtonian gravitational constant G. We show rigorously that each perturbation term is given by a line integral taken along the unperturbed geodesic between two points. Once the world function is known, it becomes possible to determine the time transfer functions giving the propagation time of a photon between its emission and its reception. We establish that the direction of a light ray as measured in the 3-space relative to a given observer can be derived from these time transfer functions, even if the metric is not stationary. We show how to deduce these functions up to any given order in G from the perturbative expansion of the world function. To illustrate the method, we carry out the calculation of the world function and of the time transfer function outside a static, spherically symmetric body up to the order G^2, the metric containing three arbitrary parameters. |
2102.08854 | Marek Cie\'slar | Marek Cie\'slar, Tomasz Bulik, Ma{\l}gorzata Cury{\l}o, Magdalena
Sieniawska, Neha Singh, Micha{\l} Bejger | Detectability of continuous gravitational waves from isolated neutron
stars in the Milky Way: the population synthesis approach | 10 pages, submitted to A&A | A&A 649, A92 (2021) | 10.1051/0004-6361/202039503 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Aims. We estimate the number of pulsars, detectable as continuous
gravitational wave sources with the current and future gravitational-wave
detectors, assuming a simple phenomenological model of evolving non-axisymmetry
of the rotating neutron star.
Methods. We employ a numerical model of the Galactic neutron star population,
with the properties established by comparison with radio observations of
isolated Galactic pulsars. We generate an arbitrarily large synthetic
population of neutron stars and evolve their period, magnetic field, and
position in space. We use a gravitational wave emission model based on
exponentially decaying ellipticity - a non-axisymmetry of the star, with no
assumption of the origin of a given ellipticity. We calculate the expected
signal in a given detector for a 1 year observations and assume a detection
criterion of the signal-to-noise ratio of 11.4 - comparable to a targeted
continous wave search. We analyze the population detectable separately in each
detector: Advanced LIGO, Advanced Virgo, and the planned Einstein Telescope. In
the calculation of the expected signal we neglect signals frequency change due
to the source spindown and the Earth motion with respect to the Solar
barycentre.
Results. With conservative values for the neutron stars evolution: supernova
rate once per 100 years, initial ellipticity $\epsilon_{0}$ = 1e-5 with no
decay of the ellipticity $\eta$ = $t_\rm{hub}$ = 1e4 Myr, the expected number
of detected neutron stars is below one: 0.15 (based on a simulation of 10 M
stars) for the Advanced LIGO detector. A broader study of the parameter space
($\epsilon_{0}$ , $\eta$) is presented. With the planned sensitivity for the
Einstein Telescope, and assuming the same ellipiticity model, the expected
detection number is: 26.4 pulsars during a 1-year long observing run.
| [
{
"created": "Wed, 17 Feb 2021 16:25:58 GMT",
"version": "v1"
}
] | 2021-05-19 | [
[
"Cieślar",
"Marek",
""
],
[
"Bulik",
"Tomasz",
""
],
[
"Curyło",
"Małgorzata",
""
],
[
"Sieniawska",
"Magdalena",
""
],
[
"Singh",
"Neha",
""
],
[
"Bejger",
"Michał",
""
]
] | Aims. We estimate the number of pulsars, detectable as continuous gravitational wave sources with the current and future gravitational-wave detectors, assuming a simple phenomenological model of evolving non-axisymmetry of the rotating neutron star. Methods. We employ a numerical model of the Galactic neutron star population, with the properties established by comparison with radio observations of isolated Galactic pulsars. We generate an arbitrarily large synthetic population of neutron stars and evolve their period, magnetic field, and position in space. We use a gravitational wave emission model based on exponentially decaying ellipticity - a non-axisymmetry of the star, with no assumption of the origin of a given ellipticity. We calculate the expected signal in a given detector for a 1 year observations and assume a detection criterion of the signal-to-noise ratio of 11.4 - comparable to a targeted continous wave search. We analyze the population detectable separately in each detector: Advanced LIGO, Advanced Virgo, and the planned Einstein Telescope. In the calculation of the expected signal we neglect signals frequency change due to the source spindown and the Earth motion with respect to the Solar barycentre. Results. With conservative values for the neutron stars evolution: supernova rate once per 100 years, initial ellipticity $\epsilon_{0}$ = 1e-5 with no decay of the ellipticity $\eta$ = $t_\rm{hub}$ = 1e4 Myr, the expected number of detected neutron stars is below one: 0.15 (based on a simulation of 10 M stars) for the Advanced LIGO detector. A broader study of the parameter space ($\epsilon_{0}$ , $\eta$) is presented. With the planned sensitivity for the Einstein Telescope, and assuming the same ellipiticity model, the expected detection number is: 26.4 pulsars during a 1-year long observing run. |
2407.08807 | Vania Vellucci | Julio Arrechea, Stefano Liberati, Vania Vellucci | Whispers from the quantum core: the ringdown of semiclassical stars | null | null | null | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by-nc-nd/4.0/ | This investigation delves into the ringdown signals produced by semiclassical
stars, which are ultra-compact, regular solutions of the Einstein equations
incorporating stress-energy contributions from quantum vacuum polarization.
These stars exhibit an approximately Schwarzschild exterior and an interior
composed of a constant-density classical fluid and a cloud of vacuum
polarization. By adjusting their compactness and density, we can alter the
internal structure of these stars without modifying the exterior. This
adaptability enables us to examine the sensitivity of the ringdown signal to
the innermost regions of the emitting object and to compare it with similar
geometries that differ substantially only at the core. Our results indicate
that echo signals are intrinsically linked to the presence of stable light
rings and can be very sensitive to the internal structure of the emitting
object. This point was previously overlooked, either due to the imposition of
reflective boundary conditions at the stellar surface or due to the assumption
of low curvature interior geometries. Specifically, for stellar-sized
semiclassical stars, we find that the interior travel time is sufficiently
prolonged to render the echoes effectively unobservable. These findings
underscore the potential efficacy of ultra-compact objects as black hole
mimickers and emphasize that any phenomenological constraints on such objects
necessitate a detailed understanding of their specific properties and core
structure.
| [
{
"created": "Thu, 11 Jul 2024 18:32:01 GMT",
"version": "v1"
}
] | 2024-07-15 | [
[
"Arrechea",
"Julio",
""
],
[
"Liberati",
"Stefano",
""
],
[
"Vellucci",
"Vania",
""
]
] | This investigation delves into the ringdown signals produced by semiclassical stars, which are ultra-compact, regular solutions of the Einstein equations incorporating stress-energy contributions from quantum vacuum polarization. These stars exhibit an approximately Schwarzschild exterior and an interior composed of a constant-density classical fluid and a cloud of vacuum polarization. By adjusting their compactness and density, we can alter the internal structure of these stars without modifying the exterior. This adaptability enables us to examine the sensitivity of the ringdown signal to the innermost regions of the emitting object and to compare it with similar geometries that differ substantially only at the core. Our results indicate that echo signals are intrinsically linked to the presence of stable light rings and can be very sensitive to the internal structure of the emitting object. This point was previously overlooked, either due to the imposition of reflective boundary conditions at the stellar surface or due to the assumption of low curvature interior geometries. Specifically, for stellar-sized semiclassical stars, we find that the interior travel time is sufficiently prolonged to render the echoes effectively unobservable. These findings underscore the potential efficacy of ultra-compact objects as black hole mimickers and emphasize that any phenomenological constraints on such objects necessitate a detailed understanding of their specific properties and core structure. |
1704.00078 | Lucas Lolli Savi | Lucas Lolli Savi | Reconsidering the horizon problem | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | It is argued that the spatial homogeneity of the early universe need not be
explained as having evolved from a previous inhomogeneous state. Rather, a
homogeneous cosmic initial condition follows from the Second Law of
Thermodynamics applied to gravitating systems.
| [
{
"created": "Fri, 31 Mar 2017 22:42:09 GMT",
"version": "v1"
},
{
"created": "Fri, 25 May 2018 21:12:33 GMT",
"version": "v2"
},
{
"created": "Tue, 19 Jun 2018 20:55:19 GMT",
"version": "v3"
}
] | 2018-06-21 | [
[
"Savi",
"Lucas Lolli",
""
]
] | It is argued that the spatial homogeneity of the early universe need not be explained as having evolved from a previous inhomogeneous state. Rather, a homogeneous cosmic initial condition follows from the Second Law of Thermodynamics applied to gravitating systems. |
1204.4524 | Kent Yagi | Kent Yagi | New Constraint on Scalar Gauss-Bonnet Gravity and a Possible Explanation
for the Excess of the Orbital Decay Rate in a Low-Mass X-ray Binary | 5 pages, no figures; Published version, typos corrected, references
added | Phys. Rev. D 86, 081504(R) (2012) | 10.1103/PhysRevD.86.081504 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It was recently shown that a black hole (BH) is the only compact object that
can acquire a scalar charge in scalar Gauss-Bonnet (sGB) theory under the small
coupling approximation. This leads to the fact that scalar radiation is emitted
from a binary containing at least one BH. In this letter, we find the
constraints on this theory from BH low-mass X-ray binaries (BH-LMXBs). The main
result of this letter is that from the orbital decay rate of A0620-00, we
obtained a conservative bound that is six orders of magnitude stronger than the
solar system bound. In addition to this, we look at XTE J1118+480, whose
orbital decay rate has been recently measured with an excess compared to the
theoretical prediction in GR due to the radiation reaction. The cause of this
excess is currently unknown. Although it is likely that the cause is of
astrophysical origin, here we investigate the possibility of explaining this
excess with the additional scalar radiation in sGB theory. We find that there
still remains a parameter range where the excess can be explained while also
satisfying the constraint obtained from A0620-00. The interesting point is that
for most of other alternative theories of gravity, it seems difficult to
explain this excess with the additional radiation. This is because it would be
difficult to evade the constraints from binary pulsars or they have already
been constrained rather strongly from other observations such as solar system
experiments. We propose several ways to determine whether the excess is caused
by the scalar radiation in sGB gravity including future gravitational wave
observations with space-borne interferometers, which can give a constraint
three orders of magnitude stronger than that from A0620-00.
| [
{
"created": "Fri, 20 Apr 2012 03:35:07 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Feb 2013 05:42:13 GMT",
"version": "v2"
}
] | 2013-02-08 | [
[
"Yagi",
"Kent",
""
]
] | It was recently shown that a black hole (BH) is the only compact object that can acquire a scalar charge in scalar Gauss-Bonnet (sGB) theory under the small coupling approximation. This leads to the fact that scalar radiation is emitted from a binary containing at least one BH. In this letter, we find the constraints on this theory from BH low-mass X-ray binaries (BH-LMXBs). The main result of this letter is that from the orbital decay rate of A0620-00, we obtained a conservative bound that is six orders of magnitude stronger than the solar system bound. In addition to this, we look at XTE J1118+480, whose orbital decay rate has been recently measured with an excess compared to the theoretical prediction in GR due to the radiation reaction. The cause of this excess is currently unknown. Although it is likely that the cause is of astrophysical origin, here we investigate the possibility of explaining this excess with the additional scalar radiation in sGB theory. We find that there still remains a parameter range where the excess can be explained while also satisfying the constraint obtained from A0620-00. The interesting point is that for most of other alternative theories of gravity, it seems difficult to explain this excess with the additional radiation. This is because it would be difficult to evade the constraints from binary pulsars or they have already been constrained rather strongly from other observations such as solar system experiments. We propose several ways to determine whether the excess is caused by the scalar radiation in sGB gravity including future gravitational wave observations with space-borne interferometers, which can give a constraint three orders of magnitude stronger than that from A0620-00. |
0812.3744 | Matt Visser | Angela White (Newcastle upon Tyne), Silke Weinfurtner (UBC Vancouver),
and Matt Visser (Victoria University of Wellington) | Signature change events: A challenge for quantum gravity? | 33 pages. 4 figures; V2: 3 references added, no physics changes; V3:
now 24 pages - significantly shortened - argument simplified and more focused
- no physics changes - this version accepted for publication in Classical and
Quantum Gravity | Class.Quant.Grav.27:045007,2010 | 10.1088/0264-9381/27/4/045007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Within the framework of either Euclidian (functional-integral) quantum
gravity or canonical general relativity the signature of the manifold is a
priori unconstrained. Furthermore, recent developments in the emergent
spacetime programme have led to a physically feasible implementation of
signature change events. This suggests that it is time to revisit the sometimes
controversial topic of signature change in general relativity. Specifically, we
shall focus on the behaviour of a quantum field subjected to a manifold
containing regions of different signature. We emphasise that, regardless of the
underlying classical theory, there are severe problems associated with any
quantum field theory residing on a signature-changing background. (Such as the
production of what is naively an infinite number of particles, with an infinite
energy density.) From the viewpoint of quantum gravity phenomenology, we
discuss possible consequences of an effective Lorentz symmetry breaking scale.
To more fully understand the physics of quantum fields exposed to finite
regions of Euclidean-signature (Riemannian) geometry, we show its similarities
with the quantum barrier penetration problem, and the super-Hubble horizon
modes encountered in cosmology. Finally we raise the question as to whether
signature change transitions could be fully understood and dynamically
generated within (modified) classical general relativity, or whether they
require the knowledge of a full theory of quantum gravity.
| [
{
"created": "Fri, 19 Dec 2008 18:12:47 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Jan 2009 23:15:36 GMT",
"version": "v2"
},
{
"created": "Wed, 6 Jan 2010 02:51:39 GMT",
"version": "v3"
}
] | 2010-04-15 | [
[
"White",
"Angela",
"",
"Newcastle upon Tyne"
],
[
"Weinfurtner",
"Silke",
"",
"UBC Vancouver"
],
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
]
] | Within the framework of either Euclidian (functional-integral) quantum gravity or canonical general relativity the signature of the manifold is a priori unconstrained. Furthermore, recent developments in the emergent spacetime programme have led to a physically feasible implementation of signature change events. This suggests that it is time to revisit the sometimes controversial topic of signature change in general relativity. Specifically, we shall focus on the behaviour of a quantum field subjected to a manifold containing regions of different signature. We emphasise that, regardless of the underlying classical theory, there are severe problems associated with any quantum field theory residing on a signature-changing background. (Such as the production of what is naively an infinite number of particles, with an infinite energy density.) From the viewpoint of quantum gravity phenomenology, we discuss possible consequences of an effective Lorentz symmetry breaking scale. To more fully understand the physics of quantum fields exposed to finite regions of Euclidean-signature (Riemannian) geometry, we show its similarities with the quantum barrier penetration problem, and the super-Hubble horizon modes encountered in cosmology. Finally we raise the question as to whether signature change transitions could be fully understood and dynamically generated within (modified) classical general relativity, or whether they require the knowledge of a full theory of quantum gravity. |
gr-qc/9708070 | Leonid Grishchuk | L. P. Grishchuk | Signatures of Quantum Gravity in the Large-Scale Universe | 20 pages; crckapb.sty; contribution based on a talk given at the 4-th
Colloque Cosmologie, Paris, June 1997 | null | null | null | gr-qc astro-ph hep-ph quant-ph | null | The quantum gravity processes that have taken place in the very early
Universe are probably responsible for the observed large-scale cosmological
perturbations. The comparison of the theory with the detected microwave
background anisotropies favors the conclusion that the very early Universe was
not driven by a scalar field with whichever scalar field potential. At the same
time, the observations allow us to conclude that there is a good probability of
a direct detection of the higher frequency relic gravitational waves with the
help of the advanced laser interferometers.
| [
{
"created": "Thu, 28 Aug 1997 15:43:49 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Grishchuk",
"L. P.",
""
]
] | The quantum gravity processes that have taken place in the very early Universe are probably responsible for the observed large-scale cosmological perturbations. The comparison of the theory with the detected microwave background anisotropies favors the conclusion that the very early Universe was not driven by a scalar field with whichever scalar field potential. At the same time, the observations allow us to conclude that there is a good probability of a direct detection of the higher frequency relic gravitational waves with the help of the advanced laser interferometers. |
1106.6114 | Hyung Won Lee | Hyung Won Lee and Kyoung Yee Kim and Yun Soo Myung | Massive gravitons dark matter scenario revisited | 13 pages, 6 figures | null | 10.1142/S0217732312501465 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We reexamine the massive graviton dark matter scenario (MGCDM) which was
recently considered as an alternative to dark energy models. When introducing
the native and effective equations of state (EoS), it is shown that there is no
phantom phase in the evolution toward the far past. Also we show that the past
accelerating phase arises from the interaction between massive graviton and
cold dark matter.
| [
{
"created": "Thu, 30 Jun 2011 05:05:29 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Lee",
"Hyung Won",
""
],
[
"Kim",
"Kyoung Yee",
""
],
[
"Myung",
"Yun Soo",
""
]
] | We reexamine the massive graviton dark matter scenario (MGCDM) which was recently considered as an alternative to dark energy models. When introducing the native and effective equations of state (EoS), it is shown that there is no phantom phase in the evolution toward the far past. Also we show that the past accelerating phase arises from the interaction between massive graviton and cold dark matter. |
1309.3183 | Jorma Louko | Jorma Louko, Samuel P. Philpott, Matthew D. Waller | Singularity resolution by lattice shifts in discretised quantum
mechanics | 16 pages, 2 figures. v2: presentational clarifications. Published
version | Phys. Rev. D 89, 044032 (2014) | 10.1103/PhysRevD.89.044032 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the robustness of singularity avoidance mechanisms in
nonrelativistic quantum mechanics on the discretised real line when lattice
points are allowed to approach a singularity of the classical potential. We
consider the attractive Coulomb potential and the attractive scale invariant
potential, on an equispaced parity-noninvariant lattice and on a non-equispaced
parity-invariant lattice, and we examine the energy eigenvalues by a
combination of analytic and numerical techniques. While the lowest one or two
eigenvalues descend to negative infinity in the singular limit, we find that
the higher eigenvalues remain finite and form degenerate pairs, close to the
eigenvalues of a theory in which a lattice point at the singularity is
regularised either by Thiemann's loop quantum gravity singularity avoidance
prescription or by a restriction to the odd parity sector. The approach to
degeneracy can be reproduced from a nonsingular discretised half-line quantum
theory by tuning a boundary condition parameter. The results show that
Thiemann's singularity avoidance prescription and the discretised half-line
boundary condition reproduce quantitatively correct features of the singular
limit spectrum apart from the lowest few eigenvalues.
| [
{
"created": "Thu, 12 Sep 2013 15:04:06 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Mar 2014 10:08:12 GMT",
"version": "v2"
}
] | 2014-03-05 | [
[
"Louko",
"Jorma",
""
],
[
"Philpott",
"Samuel P.",
""
],
[
"Waller",
"Matthew D.",
""
]
] | We investigate the robustness of singularity avoidance mechanisms in nonrelativistic quantum mechanics on the discretised real line when lattice points are allowed to approach a singularity of the classical potential. We consider the attractive Coulomb potential and the attractive scale invariant potential, on an equispaced parity-noninvariant lattice and on a non-equispaced parity-invariant lattice, and we examine the energy eigenvalues by a combination of analytic and numerical techniques. While the lowest one or two eigenvalues descend to negative infinity in the singular limit, we find that the higher eigenvalues remain finite and form degenerate pairs, close to the eigenvalues of a theory in which a lattice point at the singularity is regularised either by Thiemann's loop quantum gravity singularity avoidance prescription or by a restriction to the odd parity sector. The approach to degeneracy can be reproduced from a nonsingular discretised half-line quantum theory by tuning a boundary condition parameter. The results show that Thiemann's singularity avoidance prescription and the discretised half-line boundary condition reproduce quantitatively correct features of the singular limit spectrum apart from the lowest few eigenvalues. |
2202.02486 | Alexander S. Glasser | Eugene Kur and Alexander S. Glasser | Discrete Gravity with Local Lorentz Invariance | null | null | 10.1103/PhysRevD.106.064001 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | A novel structure-preserving algorithm for general relativity in vacuum is
derived from a lattice gauge theoretic discretization of the tetradic Palatini
action. The resulting model of discrete gravity is demonstrated to preserve
local Lorentz invariance and symplectic structure.
| [
{
"created": "Sat, 5 Feb 2022 04:12:18 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Aug 2022 19:06:44 GMT",
"version": "v2"
}
] | 2022-09-14 | [
[
"Kur",
"Eugene",
""
],
[
"Glasser",
"Alexander S.",
""
]
] | A novel structure-preserving algorithm for general relativity in vacuum is derived from a lattice gauge theoretic discretization of the tetradic Palatini action. The resulting model of discrete gravity is demonstrated to preserve local Lorentz invariance and symplectic structure. |
0707.3314 | Yun Soo Myung | Yun Soo Myung, Yong-Wan Kim, Young-Jai Park | Thermodynamic duality between RN black hole and 2D dilaton gravity | 10 pages, 3 figures, version accepted by MPLA | Mod.Phys.Lett.A23:91-98,2008 | 10.1142/S021773230802625X | null | gr-qc hep-th | null | All thermodynamic quantities of the Reissner-Nordstr\"om (RN) black hole can
be obtained from the dilaton and its potential of two dimensional (2D) dilaton
gravity. The dual relations of four thermodynamic laws are also established.
Furthermore, the near-horizon thermodynamics of the extremal RN black hole is
completely described by the Jackiw-Teitelboim theory which is obtained by
perturbing around the AdS$_2$-horizon.
| [
{
"created": "Mon, 23 Jul 2007 06:03:57 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Dec 2007 10:55:23 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Myung",
"Yun Soo",
""
],
[
"Kim",
"Yong-Wan",
""
],
[
"Park",
"Young-Jai",
""
]
] | All thermodynamic quantities of the Reissner-Nordstr\"om (RN) black hole can be obtained from the dilaton and its potential of two dimensional (2D) dilaton gravity. The dual relations of four thermodynamic laws are also established. Furthermore, the near-horizon thermodynamics of the extremal RN black hole is completely described by the Jackiw-Teitelboim theory which is obtained by perturbing around the AdS$_2$-horizon. |
1606.06918 | Mohammed Lagraa | Meriem Hadjer Lagraa, Mohammed Lagraa and Nabila Touhami | On the Hamiltonian formalism of the tetrad-gravity | 33 pages, Updated version to match with the published version in
Class. Quant. Grav | 2017, Class. Quant. Grav. 34 115010 | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a detailed analysis of the Hamiltonian constraints of the
d-dimensional tetrad-connection gravity where the non-dynamical part of the
spatial connection is fixed to zero by an adequate guage transformation. This
new action depending on the co-tetrad and the dynamical part of the spatial
connection leads to Lorentz, scalar and vectorial first-class polynomial
constraints obeying a closed algebra in terms of Poisson brackets. This algebra
closes on the structure constants instead of structure functions resulting from
the Hamiltonian formalisms based on the A.D.M. decomposition. The same algebra
of the reduced first-class constraints defined on the reduced phase-space,
where the second-class constraints are solved, is obtained in terms of Dirac
brackets. These first-class constraintslead to the same physical degrees of
freedom of the general relativity. PACS numbers: 04.20.Cv, 04.20.Fy, 11.10.Ef,
11.30.Cp
| [
{
"created": "Wed, 22 Jun 2016 11:57:47 GMT",
"version": "v1"
},
{
"created": "Fri, 30 Sep 2016 09:37:04 GMT",
"version": "v2"
},
{
"created": "Mon, 22 May 2017 15:33:03 GMT",
"version": "v3"
}
] | 2017-05-26 | [
[
"Lagraa",
"Meriem Hadjer",
""
],
[
"Lagraa",
"Mohammed",
""
],
[
"Touhami",
"Nabila",
""
]
] | We present a detailed analysis of the Hamiltonian constraints of the d-dimensional tetrad-connection gravity where the non-dynamical part of the spatial connection is fixed to zero by an adequate guage transformation. This new action depending on the co-tetrad and the dynamical part of the spatial connection leads to Lorentz, scalar and vectorial first-class polynomial constraints obeying a closed algebra in terms of Poisson brackets. This algebra closes on the structure constants instead of structure functions resulting from the Hamiltonian formalisms based on the A.D.M. decomposition. The same algebra of the reduced first-class constraints defined on the reduced phase-space, where the second-class constraints are solved, is obtained in terms of Dirac brackets. These first-class constraintslead to the same physical degrees of freedom of the general relativity. PACS numbers: 04.20.Cv, 04.20.Fy, 11.10.Ef, 11.30.Cp |
gr-qc/9810029 | Matt Visser | David Hochberg (LAEFF), Carmen Molina-Paris (Los Alamos), Matt Visser
(Washington University) | Tolman wormholes violate the strong energy condition | 8 pages, ReV-TeX 3.1 | Phys.Rev. D59 (1999) 044011 | 10.1103/PhysRevD.59.044011 | null | gr-qc | null | For an arbitrary Tolman wormhole, unconstrained by symmetry, we shall define
the bounce in terms of a three-dimensional edgeless achronal spacelike
hypersurface of minimal volume. (Zero trace for the extrinsic curvature plus a
"flare-out" condition.) This enables us to severely constrain the geometry of
spacetime at and near the bounce and to derive general theorems regarding
violations of the energy conditions--theorems that do not involve geodesic
averaging but nevertheless apply to situations much more general than the
highly symmetric FRW-based subclass of Tolman wormholes. [For example: even
under the mildest of hypotheses, the strong energy condition (SEC) must be
violated.] Alternatively, one can dispense with the minimal volume condition
and define a generic bounce entirely in terms of the motion of test particles
(future-pointing timelike geodesics), by looking at the expansion of their
timelike geodesic congruences. One re-confirms that the SEC must be violated at
or near the bounce. In contrast, it is easy to arrange for all the other
standard energy conditions to be satisfied.
| [
{
"created": "Thu, 8 Oct 1998 07:13:20 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Hochberg",
"David",
"",
"LAEFF"
],
[
"Molina-Paris",
"Carmen",
"",
"Los Alamos"
],
[
"Visser",
"Matt",
"",
"Washington University"
]
] | For an arbitrary Tolman wormhole, unconstrained by symmetry, we shall define the bounce in terms of a three-dimensional edgeless achronal spacelike hypersurface of minimal volume. (Zero trace for the extrinsic curvature plus a "flare-out" condition.) This enables us to severely constrain the geometry of spacetime at and near the bounce and to derive general theorems regarding violations of the energy conditions--theorems that do not involve geodesic averaging but nevertheless apply to situations much more general than the highly symmetric FRW-based subclass of Tolman wormholes. [For example: even under the mildest of hypotheses, the strong energy condition (SEC) must be violated.] Alternatively, one can dispense with the minimal volume condition and define a generic bounce entirely in terms of the motion of test particles (future-pointing timelike geodesics), by looking at the expansion of their timelike geodesic congruences. One re-confirms that the SEC must be violated at or near the bounce. In contrast, it is easy to arrange for all the other standard energy conditions to be satisfied. |
1604.07092 | Celio Muniz | V. B. Bezerra, M. S. Cunha, C. R. Muniz, M. O. Tahim, and H. S. Vieira | Variations in the fine structure constant constraining gravity theories | Revised version. New title. References added. 16 pages, no figures.
To appear in Europhysics Letters. arXiv admin note: text overlap with
arXiv:1510.06655 | EPL 115, 40004 (2016) | 10.1209/0295-5075/115/40004 | null | gr-qc astro-ph.SR hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate how the fine structure constant, $\alpha$,
locally varies in the presence of a static and spherically symmetric
gravitational source. The procedure consists in calculating the solution and
the energy eigenvalues of a massive scalar field around that source,
considering the weak-field regimen. From this result, we obtain expressions for
an spatially variable fine structure constant by considering suitable
modifications in the involved parameters admitting some scenarios of
semi-classical and quantum gravities. Constraints on free parameters of the
approached theories are calculated from astrophysical observations of the
emission spectra of a white dwarf. Such constraints are finally compared with
those ones obtained in the literature.
| [
{
"created": "Sun, 24 Apr 2016 23:00:30 GMT",
"version": "v1"
},
{
"created": "Sun, 25 Sep 2016 01:16:22 GMT",
"version": "v2"
}
] | 2016-09-27 | [
[
"Bezerra",
"V. B.",
""
],
[
"Cunha",
"M. S.",
""
],
[
"Muniz",
"C. R.",
""
],
[
"Tahim",
"M. O.",
""
],
[
"Vieira",
"H. S.",
""
]
] | In this paper, we investigate how the fine structure constant, $\alpha$, locally varies in the presence of a static and spherically symmetric gravitational source. The procedure consists in calculating the solution and the energy eigenvalues of a massive scalar field around that source, considering the weak-field regimen. From this result, we obtain expressions for an spatially variable fine structure constant by considering suitable modifications in the involved parameters admitting some scenarios of semi-classical and quantum gravities. Constraints on free parameters of the approached theories are calculated from astrophysical observations of the emission spectra of a white dwarf. Such constraints are finally compared with those ones obtained in the literature. |
1003.4248 | Alfredo Lopez Ortega | A. Lopez-Ortega | Area spectrum of the d-dimensional Reissner-Nordstrom black hole in the
small charge limit | 11 pages | Class. Quantum Grav. 28 (2011) 035009 | 10.1088/0264-9381/28/3/035009 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A conjecture by Hod states that for the black hole horizon the spacing of its
area spectrum is determined by the asymptotic value of its quasinormal
frequencies. Recently to overcome some difficulties, Maggiore proposes some
changes to the original Hod's conjecture. Taking into account the modifications
proposed by Maggiore we calculate the area spectrum of the d-dimensional
Reissner-Nordstrom black hole in the small charge limit.
| [
{
"created": "Mon, 22 Mar 2010 19:30:21 GMT",
"version": "v1"
},
{
"created": "Sun, 23 Jan 2011 01:19:25 GMT",
"version": "v2"
}
] | 2011-01-25 | [
[
"Lopez-Ortega",
"A.",
""
]
] | A conjecture by Hod states that for the black hole horizon the spacing of its area spectrum is determined by the asymptotic value of its quasinormal frequencies. Recently to overcome some difficulties, Maggiore proposes some changes to the original Hod's conjecture. Taking into account the modifications proposed by Maggiore we calculate the area spectrum of the d-dimensional Reissner-Nordstrom black hole in the small charge limit. |
1809.11018 | Natalia Alkofer | Natalia Alkofer | Renormalisation Group for Gravity and Dimensional Reduction | Master Thesis, Feb. 2013, U. Graz; 94 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The functional renormalisation group for the Einstein-Hilbert action is
investigated for the case of four infinite (or large) and one compact
dimension. The motivation for this study is given by the suggestion that
gravity in more than four dimensions might be able to solve the so-called
hierarchy problem of the Standard Model of elementary particle physics because
the assumed extra dimensions allow to unify the true Planck scale with the
electroweak scale. In a first step the Einstein-Hilbert theory for the
functional renormalisation group treatment of Quantum Gravity is introduced. To
set the scene for the following investigation including a compact dimension
first some corresponding calculations for four and more large dimensions are
performed and the results are found to be in agreement with already known ones.
The equations determining the renormalisation group flows are then derived for
the case of one compact dimension. These dimensionally reduced renormalisation
group equations are then numerically solved for the case of four large and one
compact dimension. Results for the four- to five-dimensional crossover are then
discussed employing two forms of the background field flow in the
Einstein-Hilbert theory for the case of one extra compact dimension.
Renormalisation group trajectories allowing for a significant lowering of the
true Planck scale to the electroweak scale are identified. The behaviour of the
running gravitational coupling at the four- to five-dimensional crossover and
the true Planck scale is displayed. Potential phenomenological implications are
briefly discussed.
| [
{
"created": "Sun, 23 Sep 2018 13:20:02 GMT",
"version": "v1"
}
] | 2018-10-01 | [
[
"Alkofer",
"Natalia",
""
]
] | The functional renormalisation group for the Einstein-Hilbert action is investigated for the case of four infinite (or large) and one compact dimension. The motivation for this study is given by the suggestion that gravity in more than four dimensions might be able to solve the so-called hierarchy problem of the Standard Model of elementary particle physics because the assumed extra dimensions allow to unify the true Planck scale with the electroweak scale. In a first step the Einstein-Hilbert theory for the functional renormalisation group treatment of Quantum Gravity is introduced. To set the scene for the following investigation including a compact dimension first some corresponding calculations for four and more large dimensions are performed and the results are found to be in agreement with already known ones. The equations determining the renormalisation group flows are then derived for the case of one compact dimension. These dimensionally reduced renormalisation group equations are then numerically solved for the case of four large and one compact dimension. Results for the four- to five-dimensional crossover are then discussed employing two forms of the background field flow in the Einstein-Hilbert theory for the case of one extra compact dimension. Renormalisation group trajectories allowing for a significant lowering of the true Planck scale to the electroweak scale are identified. The behaviour of the running gravitational coupling at the four- to five-dimensional crossover and the true Planck scale is displayed. Potential phenomenological implications are briefly discussed. |
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