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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/0610001 | Ying-Qiu Gu | Ying-Qiu Gu | The Simplification of Spinor Connection and Classical Approximation | 12 pages, no figure | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The standard spinor connection in curved space-time is represented in a
compact form. In this form the calculation is complicated, and its physical
effects are concealed. In this paper, we split spinor connection into two
vectors $\Upsilon_\mu$ and $\Omega_\mu$, where $\Upsilon_\mu$ is only related
to geometrical calculations, but $\Omega_\mu$ leads to dynamical effects, which
couples with the spin of a spinor. The representation depends only on metric
but is independent of Dirac matrices, so it is valid for both Weyl spinors and
Dirac spinor. In the new form, we can clearly define classical concepts for a
spinor and then derive its complete classical dynamics. By detailed calculation
we find the classical approximation is just Newtonian second law. The dynamical
connection $\Omega_\mu$ couples with the spin of a particle with a tiny energy
in weak field, which provides location and navigation functions for a spinor.
This term may be also important to form magnetic field of a celestial star.
From the results, we find the spinor has marvelous structure and wonderful
property, and the interaction between spinor and gravity is subtle. This study
may be also helpful to clarify the relations between relativity, quantum
mechanics and classical mechanics.
| [
{
"created": "Sat, 30 Sep 2006 02:41:21 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Dec 2006 12:31:38 GMT",
"version": "v2"
},
{
"created": "Thu, 16 Apr 2009 05:15:35 GMT",
"version": "v3"
},
{
"created": "Fri, 11 Sep 2009 12:42:45 GMT",
"version": "v4"
},
{
"c... | 2017-11-28 | [
[
"Gu",
"Ying-Qiu",
""
]
] | The standard spinor connection in curved space-time is represented in a compact form. In this form the calculation is complicated, and its physical effects are concealed. In this paper, we split spinor connection into two vectors $\Upsilon_\mu$ and $\Omega_\mu$, where $\Upsilon_\mu$ is only related to geometrical calculations, but $\Omega_\mu$ leads to dynamical effects, which couples with the spin of a spinor. The representation depends only on metric but is independent of Dirac matrices, so it is valid for both Weyl spinors and Dirac spinor. In the new form, we can clearly define classical concepts for a spinor and then derive its complete classical dynamics. By detailed calculation we find the classical approximation is just Newtonian second law. The dynamical connection $\Omega_\mu$ couples with the spin of a particle with a tiny energy in weak field, which provides location and navigation functions for a spinor. This term may be also important to form magnetic field of a celestial star. From the results, we find the spinor has marvelous structure and wonderful property, and the interaction between spinor and gravity is subtle. This study may be also helpful to clarify the relations between relativity, quantum mechanics and classical mechanics. |
gr-qc/9908030 | Philippe Ruelle | Y. Wiaux | Gauge freedom for Gravitational Wave problems in tensor-scalar theories
of gravity | 11 pages, no figure | Class.Quant.Grav. 16 (1999) 3771 | 10.1088/0264-9381/16/12/301 | UCL-IPT-99-09 | gr-qc | null | A specific choice of gauge is shown to imply a decoupling between the tensor
and scalar components of Gravitational Radiation in the context of Brans-Dicke
type theories of gravitation. The comparison of the predictions of these
theories with those of General Relativity is thereby made straightforward.
| [
{
"created": "Tue, 10 Aug 1999 09:55:55 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Oct 1999 12:18:31 GMT",
"version": "v2"
}
] | 2007-08-14 | [
[
"Wiaux",
"Y.",
""
]
] | A specific choice of gauge is shown to imply a decoupling between the tensor and scalar components of Gravitational Radiation in the context of Brans-Dicke type theories of gravitation. The comparison of the predictions of these theories with those of General Relativity is thereby made straightforward. |
2304.08456 | Mustapha Azreg-A\"inou | Mustapha Azreg-A\"inou and Hoang Ky Nguyen | A stationary axisymmetric vacuum solution for pure $R^2$ gravity | 9 pages, 4 figures | Phys. Scr. vol. 98, 125025, 2023 | 10.1088/1402-4896/ad0eb8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The closed-form expression for pure $\mathcal{R}^{2}$ vacuum solution
obtained in Phys. Rev. D \textbf{107}, 104008 (2023) lends itself to a
generalization to axisymmetric setup via the modified Newman--Janis algorithm.
We adopt the procedure put forth in Phys. Rev. D \textbf{90}, 064041 (2014)
bypassing the complexification of the radial coordinate. The procedure presumes
the existence of Boyer-Lindquist coordinates. Using the Event Horizon Telescope
Collaboration results, we model the central black hole M87{*} by the thus
obtained exact rotating metric, depending on the mass, rotation parameter and a
third dimensionless parameter. The latter is constrained upon investigating the
shadow angular size assuming mass and rotation parameters are those of M87{*}.
Stability is investigated.
| [
{
"created": "Mon, 17 Apr 2023 17:29:33 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Aug 2023 04:39:21 GMT",
"version": "v2"
},
{
"created": "Thu, 30 Nov 2023 17:24:55 GMT",
"version": "v3"
}
] | 2023-12-01 | [
[
"Azreg-Aïnou",
"Mustapha",
""
],
[
"Nguyen",
"Hoang Ky",
""
]
] | The closed-form expression for pure $\mathcal{R}^{2}$ vacuum solution obtained in Phys. Rev. D \textbf{107}, 104008 (2023) lends itself to a generalization to axisymmetric setup via the modified Newman--Janis algorithm. We adopt the procedure put forth in Phys. Rev. D \textbf{90}, 064041 (2014) bypassing the complexification of the radial coordinate. The procedure presumes the existence of Boyer-Lindquist coordinates. Using the Event Horizon Telescope Collaboration results, we model the central black hole M87{*} by the thus obtained exact rotating metric, depending on the mass, rotation parameter and a third dimensionless parameter. The latter is constrained upon investigating the shadow angular size assuming mass and rotation parameters are those of M87{*}. Stability is investigated. |
1007.2815 | Alfredo Sandoval-Villalbazo | A. L. Garcia-Perciante, A. Sandoval-Villalbazo, L.S. Garcia-Colin | On the microscopic nature of dissipative effects in special relativistic
kinetic theory | 20 pages | Journal of non-equilibrium thermodynamics 37, 4361 (2012) | 10.1515/jnet.2011.025 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A microscopic formulation of the definition of both the heat flux and the
viscous stress tensor is proposed in the framework of kinetic theory for
relativistic gases emphasizing on the physical nature of such fluxes. A Lorentz
transformation is introduced as the link between the laboratory and local
comoving frames and thus between molecular and chaotic velocities. With such
transformation, the dissipative effects can be identified as the averages of
the chaotic kinetic energy and the momentum flux out of equilibrium,
respectively. Within this framework, a kinetic foundation of the ensuing
transport equations for the relativistic gas is achieved. To our knowledge,
this result is completely novel.
| [
{
"created": "Fri, 16 Jul 2010 17:07:05 GMT",
"version": "v1"
}
] | 2012-04-20 | [
[
"Garcia-Perciante",
"A. L.",
""
],
[
"Sandoval-Villalbazo",
"A.",
""
],
[
"Garcia-Colin",
"L. S.",
""
]
] | A microscopic formulation of the definition of both the heat flux and the viscous stress tensor is proposed in the framework of kinetic theory for relativistic gases emphasizing on the physical nature of such fluxes. A Lorentz transformation is introduced as the link between the laboratory and local comoving frames and thus between molecular and chaotic velocities. With such transformation, the dissipative effects can be identified as the averages of the chaotic kinetic energy and the momentum flux out of equilibrium, respectively. Within this framework, a kinetic foundation of the ensuing transport equations for the relativistic gas is achieved. To our knowledge, this result is completely novel. |
1601.00353 | Christine Gruber | Christine Gruber | Black hole thermodynamics in finite time | 4 pages, 2 figures, Proceedings of the 14th Marcel Grossmann Meeting | null | null | null | gr-qc astro-ph.HE cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Finite-time thermodynamics provides the means to revisit ideal thermodynamic
equilibrium processes in the light of reality and investigate the energetic
"price of haste", i.e. the consequences of carrying out a process in finite
time, when perfect equilibrium cannot be awaited due to economic reasons or the
nature of the process. Employing the formalism of geometric thermodynamics, a
lower bound on the energy dissipated during a process is derived from the
thermodynamic length of that process. The notion of length is hereby defined
via a metric structure on the space of equilibrium thermodynamics, spanned by a
set of thermodynamic variables describing the system. Since the aim of
finite-time thermodynamics is to obtain realistic limitations on idealized
scenarios, it is a useful tool to reassess the efficiency of thermodynamic
processes. We examine its implications for black hole thermodynamics, in
particular scenarios inspired by the Penrose process, a thought experiment by
which work can be extracted from a rotating black hole. We consider a Kerr
black hole which, by some mechanism, is losing mass and angular momentum.
Thermodynamically speaking, such a process is described in the equilibrium
phase space of the black hole, but in reality, it is neither reversible nor
infinitely slow. We thus calculate the dissipated energy due to non-ideal
finite-time effects.
| [
{
"created": "Sun, 3 Jan 2016 23:15:24 GMT",
"version": "v1"
}
] | 2016-01-05 | [
[
"Gruber",
"Christine",
""
]
] | Finite-time thermodynamics provides the means to revisit ideal thermodynamic equilibrium processes in the light of reality and investigate the energetic "price of haste", i.e. the consequences of carrying out a process in finite time, when perfect equilibrium cannot be awaited due to economic reasons or the nature of the process. Employing the formalism of geometric thermodynamics, a lower bound on the energy dissipated during a process is derived from the thermodynamic length of that process. The notion of length is hereby defined via a metric structure on the space of equilibrium thermodynamics, spanned by a set of thermodynamic variables describing the system. Since the aim of finite-time thermodynamics is to obtain realistic limitations on idealized scenarios, it is a useful tool to reassess the efficiency of thermodynamic processes. We examine its implications for black hole thermodynamics, in particular scenarios inspired by the Penrose process, a thought experiment by which work can be extracted from a rotating black hole. We consider a Kerr black hole which, by some mechanism, is losing mass and angular momentum. Thermodynamically speaking, such a process is described in the equilibrium phase space of the black hole, but in reality, it is neither reversible nor infinitely slow. We thus calculate the dissipated energy due to non-ideal finite-time effects. |
2103.16856 | Salvatore Capozziello | Andrea Addazi, Salvatore Capozziello, and Sergei D. Odintsov | Chaotic Solutions and Black Hole Shadow in $f(R)$ gravity | 16 pages, 2 figures, accepted for publication in Phys. Lett. B | null | 10.1016/j.physletb.2021.136257 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the emergence of black hole shadow and photon-sphere in the
context of $f(R)$ gravity. It is shown that the shadow is exponentially
sensitive to linear instabilities of metric coming from some $f(R)$ solutions.
Thus, the instabilities of photon circular trajectories, delimiting the black
hole photon-sphere, are double exponentialized. Specifically we individuate two
Lyapunov exponents, rather than only one, related to two different sources of
chaos in geodesic orbits as a sort of butterfly effect. Such a result violates
the black hole chaos bound proposed by Maldacena, Shenker and Stanford for
General Relativity. We also explore the impact of the black hole metric
instabilities in $f(R)$ gravity on the quasi-normal modes. In the framework of
Extended Theories of Gravity, our analysis suggests a new paradigm to deal with
black hole shadow and gravitational waves observations coming from black hole
merging in the ringdown phase.
| [
{
"created": "Wed, 31 Mar 2021 07:11:18 GMT",
"version": "v1"
}
] | 2021-04-28 | [
[
"Addazi",
"Andrea",
""
],
[
"Capozziello",
"Salvatore",
""
],
[
"Odintsov",
"Sergei D.",
""
]
] | We discuss the emergence of black hole shadow and photon-sphere in the context of $f(R)$ gravity. It is shown that the shadow is exponentially sensitive to linear instabilities of metric coming from some $f(R)$ solutions. Thus, the instabilities of photon circular trajectories, delimiting the black hole photon-sphere, are double exponentialized. Specifically we individuate two Lyapunov exponents, rather than only one, related to two different sources of chaos in geodesic orbits as a sort of butterfly effect. Such a result violates the black hole chaos bound proposed by Maldacena, Shenker and Stanford for General Relativity. We also explore the impact of the black hole metric instabilities in $f(R)$ gravity on the quasi-normal modes. In the framework of Extended Theories of Gravity, our analysis suggests a new paradigm to deal with black hole shadow and gravitational waves observations coming from black hole merging in the ringdown phase. |
0712.1278 | Sunil Maharaj | K. Komathiraj, S. D. Maharaj | Analytical models for quark stars | 10 pages, To appear in Int. J. Mod. Phys. D | Int.J.Mod.Phys.D16:1803-1811,2007 | 10.1142/S0218271807011103 | null | gr-qc | null | We find two new classes of exact solutions to the Einstein-Maxwell system of
equations. The matter content satisfies a linear equation of state consistent
with quark matter; a particular form of one of the gravitational potentials is
specified to generate solutions. The exact solutions can be written in terms of
elementary functions, and these can be related to quark matter in the presence
of an electromagnetic field. The first class of solutions generalises the Mak
and Harko model. The second class of solutions does not admit any singularities
in the matter and gravitational potentials at the centre.
| [
{
"created": "Sat, 8 Dec 2007 11:38:56 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Komathiraj",
"K.",
""
],
[
"Maharaj",
"S. D.",
""
]
] | We find two new classes of exact solutions to the Einstein-Maxwell system of equations. The matter content satisfies a linear equation of state consistent with quark matter; a particular form of one of the gravitational potentials is specified to generate solutions. The exact solutions can be written in terms of elementary functions, and these can be related to quark matter in the presence of an electromagnetic field. The first class of solutions generalises the Mak and Harko model. The second class of solutions does not admit any singularities in the matter and gravitational potentials at the centre. |
gr-qc/0102106 | Diego M. Forni | Diego M. Forni, Mirta S. Iriondo, Carlos N. Kozameh and M. F. Parisi | Understanding singularities in Cartan's and NSF geometric structures | 22 pages, 2 figures | J.Math.Phys. 43 (2002) 1584-1597 | 10.1063/1.1408282 | null | gr-qc math-ph math.MP | null | In this work we establish a relationship between Cartan's geometric approach
to third order ODEs and the 3-dim Null Surface Formulation (NSF). We then
generalize both constructions to allow for caustics and singularities that
necessarily arise in these formalisms.
| [
{
"created": "Tue, 27 Feb 2001 20:37:46 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Forni",
"Diego M.",
""
],
[
"Iriondo",
"Mirta S.",
""
],
[
"Kozameh",
"Carlos N.",
""
],
[
"Parisi",
"M. F.",
""
]
] | In this work we establish a relationship between Cartan's geometric approach to third order ODEs and the 3-dim Null Surface Formulation (NSF). We then generalize both constructions to allow for caustics and singularities that necessarily arise in these formalisms. |
1507.02198 | Giorgio Papini | Giorgio Papini | Maximal acceleration and radiative processes | Eight pages, three figures | Mod. Phys. Lett. A, Vol. 30, No. 31 (2015) | 10.1142/S0217732315501667 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the radiation characteristics of an accelerated, charged particle
in a model due to Caianiello in which the proper acceleration of a particle of
mass $m$ has the upper limit $\mathcal{A}_m=2mc^3/\hbar$. We find two power
laws, one applicable to lower accelerations, the other more suitable for
accelerations closer to $\mathcal{A}_m$ and to the related physical singularity
in the Ricci scalar. Geometrical constraints and power spectra are also
discussed. By comparing the power laws due to the maximal acceleration with
that for particles in gravitational fields, we find that the model of
Caianiello allows, in principle, the use of charged particles as tools to
distinguish inertial from gravitational fields locally.
| [
{
"created": "Wed, 8 Jul 2015 15:29:59 GMT",
"version": "v1"
}
] | 2015-09-01 | [
[
"Papini",
"Giorgio",
""
]
] | We derive the radiation characteristics of an accelerated, charged particle in a model due to Caianiello in which the proper acceleration of a particle of mass $m$ has the upper limit $\mathcal{A}_m=2mc^3/\hbar$. We find two power laws, one applicable to lower accelerations, the other more suitable for accelerations closer to $\mathcal{A}_m$ and to the related physical singularity in the Ricci scalar. Geometrical constraints and power spectra are also discussed. By comparing the power laws due to the maximal acceleration with that for particles in gravitational fields, we find that the model of Caianiello allows, in principle, the use of charged particles as tools to distinguish inertial from gravitational fields locally. |
1105.2646 | Vladimir S. Manko | V.S. Manko, E. Ruiz and M.B. Sadovnikova | Stationary configurations of two extreme black holes obtainable from the
Kinnersley-Chitre solution | final version revised according to referee's suggestions | Phys.Rev.D84:064005,2011 | 10.1103/PhysRevD.84.064005 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Stationary axisymmetric systems of two extreme Kerr sources separated by a
massless strut, which arise as subfamilies of the well-known Kinnersley-Chitre
solution, are studied. We present explicit analytical formulas for the
individual masses and angular momenta of the constituents and establish the
range of the parameters for which such systems can be regarded as describing
black holes. The mass-angular momentum relations and the interaction force in
the black-hole configurations are also analyzed. Furthermore, we construct a
charging generalization of the Kinnersley-Chitre metric and, as applications of
the general formulas obtained, discuss two special cases describing a pair of
identical co- and counterrotating extreme Kerr-Newman black holes kept apart by
a conical singularity. From our analysis it follows in particular that the
equality $m^2-a^2-e^2=0$ relating the mass, angular momentum per unit mass and
electric charge of a single Kerr-Newman extreme black hole is no longer
verified by the analogous extreme black-hole constituents in binary
configurations.
| [
{
"created": "Fri, 13 May 2011 08:17:07 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Oct 2011 05:31:44 GMT",
"version": "v2"
}
] | 2015-05-28 | [
[
"Manko",
"V. S.",
""
],
[
"Ruiz",
"E.",
""
],
[
"Sadovnikova",
"M. B.",
""
]
] | Stationary axisymmetric systems of two extreme Kerr sources separated by a massless strut, which arise as subfamilies of the well-known Kinnersley-Chitre solution, are studied. We present explicit analytical formulas for the individual masses and angular momenta of the constituents and establish the range of the parameters for which such systems can be regarded as describing black holes. The mass-angular momentum relations and the interaction force in the black-hole configurations are also analyzed. Furthermore, we construct a charging generalization of the Kinnersley-Chitre metric and, as applications of the general formulas obtained, discuss two special cases describing a pair of identical co- and counterrotating extreme Kerr-Newman black holes kept apart by a conical singularity. From our analysis it follows in particular that the equality $m^2-a^2-e^2=0$ relating the mass, angular momentum per unit mass and electric charge of a single Kerr-Newman extreme black hole is no longer verified by the analogous extreme black-hole constituents in binary configurations. |
gr-qc/9812035 | Hakan Andreasson | Hakan Andreasson | Global foliations of matter spacetimes with Gowdy symmetry | Latex, 40 pages, submitted to CMP | Commun.Math.Phys. 206 (1999) 337-365 | 10.1007/s002200050708 | null | gr-qc | null | A global existence theorem, with respect to a geometrically defined time, is
shown for Gowdy symmetric globally hyperbolic solutions of the Einstein-Vlasov
system for arbitrary (in size) initial data. The spacetimes being studied
contain both matter and gravitational waves.
| [
{
"created": "Thu, 10 Dec 1998 19:22:09 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Andreasson",
"Hakan",
""
]
] | A global existence theorem, with respect to a geometrically defined time, is shown for Gowdy symmetric globally hyperbolic solutions of the Einstein-Vlasov system for arbitrary (in size) initial data. The spacetimes being studied contain both matter and gravitational waves. |
0808.0397 | Zurab Silagadze | O.I. Chashchina, L. Iorio, Z.K. Silagadze | Elementary derivation of the Lense-Thirring precession | 16 pages, somewhat modified, a reference added, to be published in
Acta Physica Polonica B | Acta Phys.Polon.B40:2363-2378,2009 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An elementary pedagogical derivation of the Lense-Thirring precession is
given based on the use of Hamilton vector. The Hamilton vector is an extra
constant of motion of the Kepler/Coulomb problem related simply to the more
popular Runge-Lenz vector. When a velocity-dependent Lorentz-like
gravitomagnetic force is present, the Hamilton vector, as well as the canonical
orbital momentum are no longer conserved and begin to precess. It is easy to
calculate their precession rates, which are related to the Lense-Thirring
precession of the orbit.
| [
{
"created": "Mon, 4 Aug 2008 08:34:49 GMT",
"version": "v1"
},
{
"created": "Tue, 26 May 2009 16:28:41 GMT",
"version": "v2"
}
] | 2014-11-18 | [
[
"Chashchina",
"O. I.",
""
],
[
"Iorio",
"L.",
""
],
[
"Silagadze",
"Z. K.",
""
]
] | An elementary pedagogical derivation of the Lense-Thirring precession is given based on the use of Hamilton vector. The Hamilton vector is an extra constant of motion of the Kepler/Coulomb problem related simply to the more popular Runge-Lenz vector. When a velocity-dependent Lorentz-like gravitomagnetic force is present, the Hamilton vector, as well as the canonical orbital momentum are no longer conserved and begin to precess. It is easy to calculate their precession rates, which are related to the Lense-Thirring precession of the orbit. |
1704.05076 | Suprit Singh | Ramkishor Sharma and Suprit Singh | Multifaceted Schwinger effect in de Sitter space | 7 pages and 3 figures. Selected for Kaleidoscope in Physical Review D
July 2017 | Phys. Rev. D 96, 025012 (2017) | 10.1103/PhysRevD.96.025012 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate particle production \`a la Schwinger mechanism in an
expanding, flat de Sitter patch as is relevant for the inflationary epoch of
our universe. Defining states and particle content in curved spacetime is
certainly not a unique process. There being different prescriptions on how that
can be done, we have used the Schr\"odinger formalism to define instantaneous
particle content of the state etc. This allows us to go past the adiabatic
regime to which the effect has been restricted in the previous studies and
bring out its multifaceted nature in different settings. Each of these settings
gives rise to contrasting features and behaviour as per the effect of electric
field and expansion rate on the instantaneous mean particle number. We also
quantify the degree of classicality of the process during its evolution using a
"classicality parameter" constructed out of parameters of the Wigner function
to obtain information about the quantum to classical transition in this case.
| [
{
"created": "Mon, 17 Apr 2017 18:05:38 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Sep 2017 18:00:17 GMT",
"version": "v2"
}
] | 2017-09-11 | [
[
"Sharma",
"Ramkishor",
""
],
[
"Singh",
"Suprit",
""
]
] | We investigate particle production \`a la Schwinger mechanism in an expanding, flat de Sitter patch as is relevant for the inflationary epoch of our universe. Defining states and particle content in curved spacetime is certainly not a unique process. There being different prescriptions on how that can be done, we have used the Schr\"odinger formalism to define instantaneous particle content of the state etc. This allows us to go past the adiabatic regime to which the effect has been restricted in the previous studies and bring out its multifaceted nature in different settings. Each of these settings gives rise to contrasting features and behaviour as per the effect of electric field and expansion rate on the instantaneous mean particle number. We also quantify the degree of classicality of the process during its evolution using a "classicality parameter" constructed out of parameters of the Wigner function to obtain information about the quantum to classical transition in this case. |
gr-qc/0504132 | Massimo Giovannini | Massimo Giovannini | Interacting viscous mixtures | 11 pages, figures included in eps style | Phys.Lett. B622 (2005) 349-355 | 10.1016/j.physletb.2005.07.013 | CERN-PH-TH-2005-068 | gr-qc | null | Gravitational and hydrodynamical perturbations are analysed in a relativistic
plasma containing a mixture of interacting fluids characterized by a
non-negligible bulk viscosity coefficient. The energy-momentum transfer between
the cosmological fluids, as well as the fluctuations of the bulk viscosity
coefficients, are analyzed simultaneously with the aim of deriving a
generalized set of evolution equations for the entropy and curvature
fluctuations. For typical length scales larger than the Hubble radius, the
fluctuations of the bulk viscosity coefficients and of the decay rate provide
source terms for the evolution of both the curvature and the entropy
fluctuations. According to the functional dependence of the bulk viscosity
coefficient on the energy densities of the fluids composing the system, the
mixing of entropy and curvature perturbations is scrutinized both analytically
and numerically.
| [
{
"created": "Wed, 27 Apr 2005 01:01:40 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Giovannini",
"Massimo",
""
]
] | Gravitational and hydrodynamical perturbations are analysed in a relativistic plasma containing a mixture of interacting fluids characterized by a non-negligible bulk viscosity coefficient. The energy-momentum transfer between the cosmological fluids, as well as the fluctuations of the bulk viscosity coefficients, are analyzed simultaneously with the aim of deriving a generalized set of evolution equations for the entropy and curvature fluctuations. For typical length scales larger than the Hubble radius, the fluctuations of the bulk viscosity coefficients and of the decay rate provide source terms for the evolution of both the curvature and the entropy fluctuations. According to the functional dependence of the bulk viscosity coefficient on the energy densities of the fluids composing the system, the mixing of entropy and curvature perturbations is scrutinized both analytically and numerically. |
2201.03261 | Wittaya Thipaksorn | Wittaya Thipaksorn, Stharporn Sapa, Khamphee Karwan | Coupled dark energy model inspired from general conformal transformation | 25 pages, 7 figures, 2 tables, references added, accepted for
publication in PRD, texts relevant to momentum transfer are modified | Phys. Rev. D 105, 063527 (2022) | 10.1103/PhysRevD.105.063527 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the coupled dark energy model constructed from the general conformal
transformation in which the coefficient of the conformal transformation depends
on both the scalar field and its kinetic term. Under this conformal
transformation, the action for subclass of Degenerate Higher-Order
Scalar-Tensor (DHOST) theories is related to the Einstein-Hilbert action. The
evolution of the background universe has the scaling fixed point which
corresponds to acceleration of the universe at late time. For the choices of
parameters which make the late-time scaling point stable, the fixed point
corresponding to $\phi$-matter-dominated-era ($\phi$MDE) is a saddle point, and
the universe can evolve from radiation dominated epoch through $\phi$MDE before
reaching the scaling point at late time with the cosmological parameters which
satisfy the observational bound. During the $\phi$MDE, the effective equation
of state parameter is slightly positive, so that one of possible mechanisms for
alleviating the $H_0$ tension can be achieved. In this coupled dark energy
model, the effective gravitational coupling for dark matter perturbations on
small scales can be smaller than that in the $\Lambda$CDM model. Therefore a
growth rate of the dark matter perturbations is suppressed compare with the
$\Lambda$CDM model, which implies that the $\sigma_8$ tension could be
alleviated.
| [
{
"created": "Mon, 10 Jan 2022 10:23:38 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Jan 2022 14:33:59 GMT",
"version": "v2"
},
{
"created": "Sun, 6 Mar 2022 15:05:41 GMT",
"version": "v3"
},
{
"created": "Fri, 8 Apr 2022 07:16:47 GMT",
"version": "v4"
}
] | 2022-04-12 | [
[
"Thipaksorn",
"Wittaya",
""
],
[
"Sapa",
"Stharporn",
""
],
[
"Karwan",
"Khamphee",
""
]
] | We study the coupled dark energy model constructed from the general conformal transformation in which the coefficient of the conformal transformation depends on both the scalar field and its kinetic term. Under this conformal transformation, the action for subclass of Degenerate Higher-Order Scalar-Tensor (DHOST) theories is related to the Einstein-Hilbert action. The evolution of the background universe has the scaling fixed point which corresponds to acceleration of the universe at late time. For the choices of parameters which make the late-time scaling point stable, the fixed point corresponding to $\phi$-matter-dominated-era ($\phi$MDE) is a saddle point, and the universe can evolve from radiation dominated epoch through $\phi$MDE before reaching the scaling point at late time with the cosmological parameters which satisfy the observational bound. During the $\phi$MDE, the effective equation of state parameter is slightly positive, so that one of possible mechanisms for alleviating the $H_0$ tension can be achieved. In this coupled dark energy model, the effective gravitational coupling for dark matter perturbations on small scales can be smaller than that in the $\Lambda$CDM model. Therefore a growth rate of the dark matter perturbations is suppressed compare with the $\Lambda$CDM model, which implies that the $\sigma_8$ tension could be alleviated. |
1805.11174 | Alexander Nitz | Alexander H. Nitz, Tito Dal Canton, Derek Davis, Steven Reyes | PyCBC Live: Rapid Detection of Gravitational Waves from Compact Binary
Mergers | 10 pages, 5 figures, submitted to Physical Review D | Phys. Rev. D 98, 024050 (2018) | 10.1103/PhysRevD.98.024050 | LIGO-P1800139 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce an efficient and straightforward technique for rapidly detecting
gravitational waves from compact binary mergers. We show that this method
achieves the low latencies required to alert electromagnetic partners of
candidate binary mergers, aids in data monitoring, and makes use of
multidetector networks for sky localization. This approach was instrumental to
the analysis of gravitational-wave candidates during the second observing run
of Advanced LIGO, including the period of coincident operation with Advanced
Virgo, and in particular the analysis of the first observed binary neutron star
merger GW170817, where it led to the first tightly localized sky map
($31~\mathrm{deg}^2$) used to identify AT 2017gfo. Operation of this analysis
also enabled the initial discovery of GW170104 and GW170608 despite non-nominal
observing of the instrument.
| [
{
"created": "Mon, 28 May 2018 21:00:54 GMT",
"version": "v1"
}
] | 2018-08-08 | [
[
"Nitz",
"Alexander H.",
""
],
[
"Canton",
"Tito Dal",
""
],
[
"Davis",
"Derek",
""
],
[
"Reyes",
"Steven",
""
]
] | We introduce an efficient and straightforward technique for rapidly detecting gravitational waves from compact binary mergers. We show that this method achieves the low latencies required to alert electromagnetic partners of candidate binary mergers, aids in data monitoring, and makes use of multidetector networks for sky localization. This approach was instrumental to the analysis of gravitational-wave candidates during the second observing run of Advanced LIGO, including the period of coincident operation with Advanced Virgo, and in particular the analysis of the first observed binary neutron star merger GW170817, where it led to the first tightly localized sky map ($31~\mathrm{deg}^2$) used to identify AT 2017gfo. Operation of this analysis also enabled the initial discovery of GW170104 and GW170608 despite non-nominal observing of the instrument. |
gr-qc/0104078 | Malakhaltsev Mikhail A. | V. Bashkov, M. Malakhaltsev | Relativistic mechanics on rotating disk | null | null | null | null | gr-qc | null | We find equations of particle motion from the point of view of observer on a
rotating disk, and demonstrate that a particle moving along a rotating disk is
influenced by forces arising from geometry. They can be considered as analogs
of the centrifugal forces and the Coriolis forces.
| [
{
"created": "Wed, 25 Apr 2001 11:36:21 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Bashkov",
"V.",
""
],
[
"Malakhaltsev",
"M.",
""
]
] | We find equations of particle motion from the point of view of observer on a rotating disk, and demonstrate that a particle moving along a rotating disk is influenced by forces arising from geometry. They can be considered as analogs of the centrifugal forces and the Coriolis forces. |
0807.3619 | Manfred Requardt | M. Requardt | About the Minimal Resolution of Space-Time Grains in Experimental
Quantum Gravity | 28 pages, Latex | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We critically analyse and compare various recent thought experiments,
performed by Amelino-Camelia, Ng et al., Baez et al., Adler et al., and
ourselves, concerning the (thought)experimental accessibility of the Planck
scale by space-time measurements. We show that a closer inspection of the
working of the measuring devices, by taking their microscopic quantum many-body
nature in due account, leads to deeper insights concerning the extreme limits
of the precision of space-time measurements. Among other things, we show how
certain constraints like e.g. the Schwarzschild constraint can be circumvented
and that quantum fluctuations being present in the measuring devices can be
reduced by designing more intelligent measuring instruments. Consequences for
various phenomenological quantum gravity models are discussed.
| [
{
"created": "Wed, 23 Jul 2008 08:19:00 GMT",
"version": "v1"
}
] | 2008-07-24 | [
[
"Requardt",
"M.",
""
]
] | We critically analyse and compare various recent thought experiments, performed by Amelino-Camelia, Ng et al., Baez et al., Adler et al., and ourselves, concerning the (thought)experimental accessibility of the Planck scale by space-time measurements. We show that a closer inspection of the working of the measuring devices, by taking their microscopic quantum many-body nature in due account, leads to deeper insights concerning the extreme limits of the precision of space-time measurements. Among other things, we show how certain constraints like e.g. the Schwarzschild constraint can be circumvented and that quantum fluctuations being present in the measuring devices can be reduced by designing more intelligent measuring instruments. Consequences for various phenomenological quantum gravity models are discussed. |
1206.1164 | Stefan Hollands | Stefan Hollands and Akihiro Ishibashi | Black hole uniqueness theorems in higher dimensional spacetimes | Extended version of "Topical Review" article commissioned by Class.
Quant. Grav., 66 pages, several figures, Latex. v2: Added section on near
horizon geometries, edited/added references | null | 10.1088/0264-9381/29/16/163001 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review uniqueness theorems as well as other general results about higher
dimensional black hole spacetimes. This includes in particular theorems about
the topology of higher dimensional spacetimes, theorems about their symmetries
(rigidity theorem), and the classification of supersymmetric black holes. We
outline the basic ideas underlying the proofs of these statements, and we also
indicate ways to generalize some of these results to more general contexts,
such as more complicated theories.
| [
{
"created": "Wed, 6 Jun 2012 09:55:59 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Aug 2012 11:52:48 GMT",
"version": "v2"
}
] | 2015-06-05 | [
[
"Hollands",
"Stefan",
""
],
[
"Ishibashi",
"Akihiro",
""
]
] | We review uniqueness theorems as well as other general results about higher dimensional black hole spacetimes. This includes in particular theorems about the topology of higher dimensional spacetimes, theorems about their symmetries (rigidity theorem), and the classification of supersymmetric black holes. We outline the basic ideas underlying the proofs of these statements, and we also indicate ways to generalize some of these results to more general contexts, such as more complicated theories. |
1901.00932 | Stanley Deser | S.Deser | Non-Lagrangian Gauge Field Models are Physically Excluded | Published version | Phys.Lett. B790 (2019) 408-409 | 10.1016/j.physletb.2019.01.044 | BRX-TH 6645, CALT-TH 2019 001 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | While non-action generated, but identically conserved,-abelian and non-gauge
vectors exist, they are unsuitable for building alternate field equations
because they have no stress-tensor, hence do not permit Poincare generators
and, most phiyically, cannot couple consistently to gravity. Separately, their
geometric analogues -covariantly conserved non-Lagrangian symmetric
tensors-probably do not exist, but their weak field, abelian counterparts do,
and share the vector fields' absence of generators.
| [
{
"created": "Thu, 3 Jan 2019 22:45:28 GMT",
"version": "v1"
},
{
"created": "Fri, 25 Jan 2019 18:51:19 GMT",
"version": "v2"
}
] | 2019-03-14 | [
[
"Deser",
"S.",
""
]
] | While non-action generated, but identically conserved,-abelian and non-gauge vectors exist, they are unsuitable for building alternate field equations because they have no stress-tensor, hence do not permit Poincare generators and, most phiyically, cannot couple consistently to gravity. Separately, their geometric analogues -covariantly conserved non-Lagrangian symmetric tensors-probably do not exist, but their weak field, abelian counterparts do, and share the vector fields' absence of generators. |
gr-qc/9905002 | Carey Carpenter Briggs | C. C. Briggs | General Expressions for the Coefficients of Chern Forms Up to the 13th
Order in Curvature | 27 pages | null | null | null | gr-qc | null | General expressions are given for the coefficients of Chern forms up to the
13th order in curvature in terms of the Riemann-Christoffel curvature tensor
and some of its concomitants (e.g., Pontrjagin's characteristic tensors) for
n-dimensional differentiable manifolds having a general linear connection.
| [
{
"created": "Mon, 3 May 1999 02:59:27 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Briggs",
"C. C.",
""
]
] | General expressions are given for the coefficients of Chern forms up to the 13th order in curvature in terms of the Riemann-Christoffel curvature tensor and some of its concomitants (e.g., Pontrjagin's characteristic tensors) for n-dimensional differentiable manifolds having a general linear connection. |
gr-qc/9209011 | Steve Carlip | S. Carlip | The Modular Group, Operator Ordering, and Time in (2+1)-Dimensional
Gravity | 8 pages, LaTeX | Phys.Rev.D47:4520-4524,1993 | 10.1103/PhysRevD.47.4520 | UCD-92-23 | gr-qc hep-th | null | A choice of time-slicing in classical general relativity permits the
construction of time-dependent wave functions in the ``frozen time''
Chern-Simons formulation of $(2+1)$-dimensional quantum gravity. Because of
operator ordering ambiguities, however, these wave functions are not unique. It
is shown that when space has the topology of a torus, suitable operator
orderings give rise to wave functions that transform under the modular group as
automorphic functions of arbitrary weights, with dynamics determined by the
corresponding Maass Laplacians on moduli space.
| [
{
"created": "Fri, 25 Sep 1992 00:12:08 GMT",
"version": "v1"
}
] | 2010-04-28 | [
[
"Carlip",
"S.",
""
]
] | A choice of time-slicing in classical general relativity permits the construction of time-dependent wave functions in the ``frozen time'' Chern-Simons formulation of $(2+1)$-dimensional quantum gravity. Because of operator ordering ambiguities, however, these wave functions are not unique. It is shown that when space has the topology of a torus, suitable operator orderings give rise to wave functions that transform under the modular group as automorphic functions of arbitrary weights, with dynamics determined by the corresponding Maass Laplacians on moduli space. |
2005.03417 | Thomas P. Kling | Thomas P. Kling, Faizuddin Ahmed and Megan Lalumiere | Wave Fronts in a Causality Violating Godel-Type Metric | final version to Advances in High Energy Physics | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The light-rays and wave fronts in a flat class of Godel-type metric are
examined to reveal the causality violating features of the space-time.
Non-causal features demonstrated by the development of unusual wave front
singularities are shown to be related to the non-monotonic advance of time
along the light rays, as measured by a system of observers at rest with respect
to one another with synchronized clocks.
| [
{
"created": "Thu, 7 May 2020 12:32:53 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Jul 2020 10:47:31 GMT",
"version": "v2"
}
] | 2020-07-10 | [
[
"Kling",
"Thomas P.",
""
],
[
"Ahmed",
"Faizuddin",
""
],
[
"Lalumiere",
"Megan",
""
]
] | The light-rays and wave fronts in a flat class of Godel-type metric are examined to reveal the causality violating features of the space-time. Non-causal features demonstrated by the development of unusual wave front singularities are shown to be related to the non-monotonic advance of time along the light rays, as measured by a system of observers at rest with respect to one another with synchronized clocks. |
1304.6381 | T. Damour | Thibault Damour and Philippe Spindel | Quantum Supersymmetric Cosmology and its Hidden Kac-Moody Structure | 5 pages; a few additional explanatory sentences (in the abstract and
the introduction) | null | 10.1088/0264-9381/30/16/162001 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the quantum dynamics of a supersymmetric squashed three-sphere by
dimensionally reducing (to one timelike dimension) the action of D=4 simple
supergravity for an SO(3)-homogeneous (Bianchi IX) cosmological model. The
quantization of the homogeneous gravitino field leads to a 64-dimensional
fermionic Hilbert space. The algebra of the supersymmetry constraints and of
the Hamiltonian one is found to close. One finds that the quantum Hamiltonian
is built from operators that generate a 64-dimensional representation of the
(infinite-dimensional) maximally compact sub-algebra of the rank-3 hyperbolic
Kac-Moody algebra AE_3. Some exponentials of these operators generate a
spinorial extension of the Weyl group of AE_3 which describe (in the small
wavelength limit) the chaotic quantum evolution of the universe near the
cosmological singularity.
| [
{
"created": "Tue, 23 Apr 2013 18:57:07 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Jun 2013 08:58:47 GMT",
"version": "v2"
}
] | 2015-06-15 | [
[
"Damour",
"Thibault",
""
],
[
"Spindel",
"Philippe",
""
]
] | We study the quantum dynamics of a supersymmetric squashed three-sphere by dimensionally reducing (to one timelike dimension) the action of D=4 simple supergravity for an SO(3)-homogeneous (Bianchi IX) cosmological model. The quantization of the homogeneous gravitino field leads to a 64-dimensional fermionic Hilbert space. The algebra of the supersymmetry constraints and of the Hamiltonian one is found to close. One finds that the quantum Hamiltonian is built from operators that generate a 64-dimensional representation of the (infinite-dimensional) maximally compact sub-algebra of the rank-3 hyperbolic Kac-Moody algebra AE_3. Some exponentials of these operators generate a spinorial extension of the Weyl group of AE_3 which describe (in the small wavelength limit) the chaotic quantum evolution of the universe near the cosmological singularity. |
2404.14550 | Eduardo Bittencourt | \'Erico Goulart and Eduardo Bittencourt | Photon traps in nonlinear electrodynamics | 13 pages, 5 figures | null | null | null | gr-qc physics.optics | http://creativecommons.org/licenses/by/4.0/ | We demonstrate the existence of photon traps within the framework of
nonlinear electrodynamics. The trapping mechanism is based on the fact that,
for null background fields, the optical metric reduces to the Kerr-Schild form,
which plays a prominent role in the context of black hole physics. We then
construct explicit examples where photons are confined in a region of
spacetime, such that a distant observer cannot interact with them. Finally, we
argue that the trapping scheme is quite universal, being entirely compatible
with causality, energy conditions, and hyperbolicity.
| [
{
"created": "Mon, 22 Apr 2024 19:43:35 GMT",
"version": "v1"
}
] | 2024-04-24 | [
[
"Goulart",
"Érico",
""
],
[
"Bittencourt",
"Eduardo",
""
]
] | We demonstrate the existence of photon traps within the framework of nonlinear electrodynamics. The trapping mechanism is based on the fact that, for null background fields, the optical metric reduces to the Kerr-Schild form, which plays a prominent role in the context of black hole physics. We then construct explicit examples where photons are confined in a region of spacetime, such that a distant observer cannot interact with them. Finally, we argue that the trapping scheme is quite universal, being entirely compatible with causality, energy conditions, and hyperbolicity. |
gr-qc/0205105 | Dr Mayeul Arminjon | Mayeul Arminjon | The Scalar Ether-Theory of Gravitation and its First Test in Celestial
Mechanics | LaTeX, 6 pages, one figure. Text of a talk at the 5th Friedmann
International Seminar on Gravitation and Cosmology, Joao Pessoa (Brazil),
23-30 April 2002. Will be submitted to a special issue of Int. J. Mod.
Phys./A | Int.J.Mod.Phys. A17 (2002) 4203-4208 | 10.1142/S0217751X0201323X | null | gr-qc astro-ph | null | The motivations for investigating a theory of gravitation based on a concept
of "ether" are discussed-- a crucial point is the existence of an alternative
interpretation of special relativity, named the Lorentz-Poincar\'e ether
theory. The basic equations of one such theory of gravity, based on just one
scalar field, are presented. To check this theory in celestial mechanics, an
"asymptotic" scheme of post-Newtonian (PN) approximation is summarized and its
difference with the standard PN scheme is emphasized. The derivation of PN
equations of motion for the mass centers, based on the asymptotic scheme, is
outlined. They are implemented for the major bodies of the solar system and the
prediction for Mercury is compared with an ephemeris based on general
relativity.
| [
{
"created": "Fri, 24 May 2002 16:39:22 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Arminjon",
"Mayeul",
""
]
] | The motivations for investigating a theory of gravitation based on a concept of "ether" are discussed-- a crucial point is the existence of an alternative interpretation of special relativity, named the Lorentz-Poincar\'e ether theory. The basic equations of one such theory of gravity, based on just one scalar field, are presented. To check this theory in celestial mechanics, an "asymptotic" scheme of post-Newtonian (PN) approximation is summarized and its difference with the standard PN scheme is emphasized. The derivation of PN equations of motion for the mass centers, based on the asymptotic scheme, is outlined. They are implemented for the major bodies of the solar system and the prediction for Mercury is compared with an ephemeris based on general relativity. |
0803.0944 | Miguel S\'anchez | Antonio N. Bernal, Miguel S\'anchez, Francisco Jos\'e Soler Gil | Physics from scratch. Letter on M. Tegmark's ``The Mathematical
Universe'' | 7 pages, latex | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a recent article, M. Tegmark poses the hypothesis that our known universe
is a ``baggage free'' mathematical structure among many other possible ones,
which also correspond to other physical universes --Mathematical Universe
Hypothesis, MUH. Naturally, questions arise, such as how to obtain the physical
properties of our world from the mathematical structure, or how many
possibilities exist for a Universe minimally similar to ours.
In this letter we present some results which can be regarded as a
strengthening of MUH, as they give some hints on the derivation of spacetime in
current physics from a baggage free mathematical structure.
Concretely, we argue that the set of mathematical structures which can be
interpreted as a description of a spacetime is drastically reduced, if one
admits some natural postulates on minimal symmetry. Furthermore, the apparently
very particular form of classical Galilei-Newton and relativistic spacetimes,
is not arbitrary and cannot be regarded as ``two possibilities among
arbitrarily many others''. In fact, such theories are determined by a single
mathematical structure which only permits four possible types of spacetimes.
Finally, we show how the minimal postulates on symmetry can be endowed with a
simple physical interpretation, i.e., they acquire ``baggage'' in a natural
way.
| [
{
"created": "Thu, 6 Mar 2008 19:07:40 GMT",
"version": "v1"
}
] | 2008-03-07 | [
[
"Bernal",
"Antonio N.",
""
],
[
"Sánchez",
"Miguel",
""
],
[
"Gil",
"Francisco José Soler",
""
]
] | In a recent article, M. Tegmark poses the hypothesis that our known universe is a ``baggage free'' mathematical structure among many other possible ones, which also correspond to other physical universes --Mathematical Universe Hypothesis, MUH. Naturally, questions arise, such as how to obtain the physical properties of our world from the mathematical structure, or how many possibilities exist for a Universe minimally similar to ours. In this letter we present some results which can be regarded as a strengthening of MUH, as they give some hints on the derivation of spacetime in current physics from a baggage free mathematical structure. Concretely, we argue that the set of mathematical structures which can be interpreted as a description of a spacetime is drastically reduced, if one admits some natural postulates on minimal symmetry. Furthermore, the apparently very particular form of classical Galilei-Newton and relativistic spacetimes, is not arbitrary and cannot be regarded as ``two possibilities among arbitrarily many others''. In fact, such theories are determined by a single mathematical structure which only permits four possible types of spacetimes. Finally, we show how the minimal postulates on symmetry can be endowed with a simple physical interpretation, i.e., they acquire ``baggage'' in a natural way. |
gr-qc/0103020 | Yuri N. Obukhov | Friedrich W. Hehl and Yuri N. Obukhov | On the energy-momentum current of the electromagnetic field in a
pre-metric axiomatic approach. I | 25 pages, Revtex, Dedicated to the memory of our friend and colleague
Ruggiero de Ritis from Napoli | null | null | null | gr-qc hep-th physics.class-ph | null | We complete a metric-free axiomatic framework for electrodynamics by
introducing the appropriate energy-momentum current Sigma of the
electromagnetic field. We start from the Lorentz force density and motivate the
form of Sigma. Then we postulate it (fourth axiom) and discuss its properties.
In particular, it is found that Sigma is traceless and invariant under an
electric-magnetic reciprocity transformation. By using the Maxwell-Lorentz
spacetime relation (fifth axiom), Sigma is also shown to be symmetric, that is,
it has 9 independent components
| [
{
"created": "Wed, 7 Mar 2001 22:20:28 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Hehl",
"Friedrich W.",
""
],
[
"Obukhov",
"Yuri N.",
""
]
] | We complete a metric-free axiomatic framework for electrodynamics by introducing the appropriate energy-momentum current Sigma of the electromagnetic field. We start from the Lorentz force density and motivate the form of Sigma. Then we postulate it (fourth axiom) and discuss its properties. In particular, it is found that Sigma is traceless and invariant under an electric-magnetic reciprocity transformation. By using the Maxwell-Lorentz spacetime relation (fifth axiom), Sigma is also shown to be symmetric, that is, it has 9 independent components |
1902.07968 | Aroonkumar Beesham | Aroonkumar Beesham and Alireza Sepehri | Expansion and contraction of accretion disks of a rotating thermal BIon
in a Rindler space-time | 12 pages, 3 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider the evolution of accretion disks of a rotating
BIon in a Rindler space-time. This space-time emerges because of the
acceleration of the disks in a BIon. A BIon is constructed from a pair of
accretion disks that are connected by a wormhole. We will show that in a
rotating BIon, by increasing the rotation velocity, the area of one accretion
disk grows, while the area of the other shrinks. Also, we consider four types
of accreion disks which are produced in a Rindler space-time.
| [
{
"created": "Thu, 21 Feb 2019 11:12:21 GMT",
"version": "v1"
}
] | 2019-02-22 | [
[
"Beesham",
"Aroonkumar",
""
],
[
"Sepehri",
"Alireza",
""
]
] | In this paper, we consider the evolution of accretion disks of a rotating BIon in a Rindler space-time. This space-time emerges because of the acceleration of the disks in a BIon. A BIon is constructed from a pair of accretion disks that are connected by a wormhole. We will show that in a rotating BIon, by increasing the rotation velocity, the area of one accretion disk grows, while the area of the other shrinks. Also, we consider four types of accreion disks which are produced in a Rindler space-time. |
1710.09294 | Bahia Si Lakhal | Houda Mansour, Bahia Si Lakhal and Abdelkader Yanallah | Weakly Charged Compact Stars in $f \left( R \right)$ gravity | 12 pages, 7 figures | null | 10.1088/1475-7516/2018/06/006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study electrically charged compact stars in the framework of extended
theory of gravity (ETG). We assume that the charge density is proportional to
the energy density. The polytropic equation of state is chosen to describe the
state of the charged perfect fluid. We aim to find the Oppenheimer Volkoff (OV)
mass limit for charged compact stars. A detailed numerical study is performed.
We show the dependence of the mass-radius diagram of the spheres on the values
of the perturbatif parameter $\beta$, the polytropic exponent $\gamma$ and the
charge fraction $\alpha$. Our results are compared with those found in the
literature in the case of applying General Relativity (GR).
| [
{
"created": "Wed, 25 Oct 2017 15:09:41 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Nov 2017 20:00:34 GMT",
"version": "v2"
}
] | 2022-08-03 | [
[
"Mansour",
"Houda",
""
],
[
"Lakhal",
"Bahia Si",
""
],
[
"Yanallah",
"Abdelkader",
""
]
] | We study electrically charged compact stars in the framework of extended theory of gravity (ETG). We assume that the charge density is proportional to the energy density. The polytropic equation of state is chosen to describe the state of the charged perfect fluid. We aim to find the Oppenheimer Volkoff (OV) mass limit for charged compact stars. A detailed numerical study is performed. We show the dependence of the mass-radius diagram of the spheres on the values of the perturbatif parameter $\beta$, the polytropic exponent $\gamma$ and the charge fraction $\alpha$. Our results are compared with those found in the literature in the case of applying General Relativity (GR). |
gr-qc/0403064 | Mu-Lin Yan | Hua Bai, Mu-Lin Yan | Quantum Horizons | 7 pages, No figures, LaTeX file | null | null | USTC-ICTS-04-05 | gr-qc hep-ph hep-th | null | Treating macro-black hole as quantum states, and using Brown-York quaselocal
gravitational energy definition and Heisenberg uncertainty principle, we find
out the classical horizon with singularity spreads into a quantum horizon in
which the space-time is non-commutative and the spread range is determined
dynamically. A Quantum Field Theory (QFT) model in curved space with quantum
horizon is constructed. By using it, the black hole entropy and the Hawking
temperature are calculated successfully. The $\phi-$field mode number is
predicted and our quantum horizon model favors to support the Minimal
Super-symmetric Standard Model.
| [
{
"created": "Mon, 15 Mar 2004 16:05:26 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Mar 2004 15:24:46 GMT",
"version": "v2"
},
{
"created": "Sun, 20 Jun 2004 15:01:35 GMT",
"version": "v3"
},
{
"created": "Fri, 11 Feb 2005 09:17:39 GMT",
"version": "v4"
}
] | 2007-05-23 | [
[
"Bai",
"Hua",
""
],
[
"Yan",
"Mu-Lin",
""
]
] | Treating macro-black hole as quantum states, and using Brown-York quaselocal gravitational energy definition and Heisenberg uncertainty principle, we find out the classical horizon with singularity spreads into a quantum horizon in which the space-time is non-commutative and the spread range is determined dynamically. A Quantum Field Theory (QFT) model in curved space with quantum horizon is constructed. By using it, the black hole entropy and the Hawking temperature are calculated successfully. The $\phi-$field mode number is predicted and our quantum horizon model favors to support the Minimal Super-symmetric Standard Model. |
gr-qc/9806102 | Kirill A. Bronnikov | K.A. Bronnikov | Gravitating Brane Systems: Some General Theorems | 13 pages, Latex2e, 1 Latex figure, uses bezier.sty | J.Math.Phys. 40 (1999) 924-938 | 10.1063/1.532695 | RGS-VNIIMS-11/98 | gr-qc hep-th | null | Multidimensional gravity interacting with intersecting electric and magnetic
$p$-branes is considered for fields depending on a single variable. Some
general features of the system behaviour are revealed without solving the field
equations. Thus, essential asymptotic properties of isotropic cosmologies are
indicated for different signs of spatial curvature; a no-hair-type theorem and
a single-time theorem for black holes are proved (the latter makes sense in
models with multiple time coordinates). The validity of the general
observations is verified for a class of exact solutions known for the cases
when certain vectors, built from the input parameters of the model, are either
orthogonal in minisuperspace, or form mutually orthogonal subsystems. From the
non-existence of Lorentzian wormholes, a universal restriction is obtained,
applicable to orthogonal or block-orthogonal subsystems of any $p$-brane
system.
| [
{
"created": "Fri, 26 Jun 1998 07:43:54 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Bronnikov",
"K. A.",
""
]
] | Multidimensional gravity interacting with intersecting electric and magnetic $p$-branes is considered for fields depending on a single variable. Some general features of the system behaviour are revealed without solving the field equations. Thus, essential asymptotic properties of isotropic cosmologies are indicated for different signs of spatial curvature; a no-hair-type theorem and a single-time theorem for black holes are proved (the latter makes sense in models with multiple time coordinates). The validity of the general observations is verified for a class of exact solutions known for the cases when certain vectors, built from the input parameters of the model, are either orthogonal in minisuperspace, or form mutually orthogonal subsystems. From the non-existence of Lorentzian wormholes, a universal restriction is obtained, applicable to orthogonal or block-orthogonal subsystems of any $p$-brane system. |
1906.05531 | Yorgo Senikoglu | Tekin Dereli, Yorgo Senikoglu | Dark range of $\omega$ in Brans-Dicke gravity | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The variational field equations of Brans-Dicke scalar-tensor theory of
gravitation are presented in a Riemannian and non-Riemannian setting in the
language of exterior differential forms over 4-dimensional spacetime. In Rosen
coordinates, the equations of motion of non-spinning test masses are considered
in a gravitational plane wave setup and detailed to interpret a scalar field
$\alpha$ as a candidate for dark energy for negative values of the Brans-Dicke
parameter $-3/2 < \omega < 0$ .
| [
{
"created": "Thu, 13 Jun 2019 07:57:51 GMT",
"version": "v1"
}
] | 2019-06-14 | [
[
"Dereli",
"Tekin",
""
],
[
"Senikoglu",
"Yorgo",
""
]
] | The variational field equations of Brans-Dicke scalar-tensor theory of gravitation are presented in a Riemannian and non-Riemannian setting in the language of exterior differential forms over 4-dimensional spacetime. In Rosen coordinates, the equations of motion of non-spinning test masses are considered in a gravitational plane wave setup and detailed to interpret a scalar field $\alpha$ as a candidate for dark energy for negative values of the Brans-Dicke parameter $-3/2 < \omega < 0$ . |
2210.06194 | Charles Badger | Charles Badger, Katarina Martinovic, Alejandro Torres-Forn\'e, Mairi
Sakellariadou, Jos\'e A. Font | Dictionary learning: a novel approach to detecting binary black holes in
the presence of Galactic noise with LISA | 6 pages, 3 figures | null | 10.1103/PhysRevLett.130.091401 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The noise produced by the inspiral of millions of white dwarf binaries in the
Milky Way may pose a threat to one of the main goals of the space-based LISA
mission: the detection of massive black hole binary mergers. We present a novel
study for reconstruction of merger waveforms in the presence of Galactic
confusion noise using dictionary learning. We discuss the limitations of
untangling signals from binaries with total mass from $10^2 M_{\odot}$ to $10^4
M_{\odot}$. Our method proves extremely successful for binaries with total mass
greater than $\sim 3\times 10^3$ $ M_{\odot}$ up to redshift 3 in conservative
scenarios, and up to redshift 7.5 in optimistic scenarios. In addition,
consistently good waveform reconstruction of merger events is found if the
signal-to-noise ratio is approximately 5 or greater.
| [
{
"created": "Wed, 12 Oct 2022 13:26:28 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Oct 2022 13:43:03 GMT",
"version": "v2"
}
] | 2023-03-08 | [
[
"Badger",
"Charles",
""
],
[
"Martinovic",
"Katarina",
""
],
[
"Torres-Forné",
"Alejandro",
""
],
[
"Sakellariadou",
"Mairi",
""
],
[
"Font",
"José A.",
""
]
] | The noise produced by the inspiral of millions of white dwarf binaries in the Milky Way may pose a threat to one of the main goals of the space-based LISA mission: the detection of massive black hole binary mergers. We present a novel study for reconstruction of merger waveforms in the presence of Galactic confusion noise using dictionary learning. We discuss the limitations of untangling signals from binaries with total mass from $10^2 M_{\odot}$ to $10^4 M_{\odot}$. Our method proves extremely successful for binaries with total mass greater than $\sim 3\times 10^3$ $ M_{\odot}$ up to redshift 3 in conservative scenarios, and up to redshift 7.5 in optimistic scenarios. In addition, consistently good waveform reconstruction of merger events is found if the signal-to-noise ratio is approximately 5 or greater. |
1105.3105 | John Barrow | John D. Barrow and Douglas J. Shaw | The Value of the Cosmological Constant | 6 pages. This article received Third Prize in the 2011 Gravity
Research Foundation Awards for Essays on Gravitation | General Relativity and Gravitation 43, 2555-2560 (2011) | 10.1007/s10714-011-1199-1 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We make the cosmological constant, {\Lambda}, into a field and restrict the
variations of the action with respect to it by causality. This creates an
additional Einstein constraint equation. It restricts the solutions of the
standard Einstein equations and is the requirement that the cosmological wave
function possess a classical limit. When applied to the Friedmann metric it
requires that the cosmological constant measured today, t_{U}, be {\Lambda} ~
t_{U}^(-2) ~ 10^(-122), as observed. This is the classical value of {\Lambda}
that dominates the wave function of the universe. Our new field equation
determines {\Lambda} in terms of other astronomically measurable quantities.
Specifically, it predicts that the spatial curvature parameter of the universe
is {\Omega}_{k0} \equiv -k/a_(0)^(2)H^2= -0.0055, which will be tested by
Planck Satellite data. Our theory also creates a new picture of self-consistent
quantum cosmological history.
| [
{
"created": "Mon, 16 May 2011 14:35:51 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Barrow",
"John D.",
""
],
[
"Shaw",
"Douglas J.",
""
]
] | We make the cosmological constant, {\Lambda}, into a field and restrict the variations of the action with respect to it by causality. This creates an additional Einstein constraint equation. It restricts the solutions of the standard Einstein equations and is the requirement that the cosmological wave function possess a classical limit. When applied to the Friedmann metric it requires that the cosmological constant measured today, t_{U}, be {\Lambda} ~ t_{U}^(-2) ~ 10^(-122), as observed. This is the classical value of {\Lambda} that dominates the wave function of the universe. Our new field equation determines {\Lambda} in terms of other astronomically measurable quantities. Specifically, it predicts that the spatial curvature parameter of the universe is {\Omega}_{k0} \equiv -k/a_(0)^(2)H^2= -0.0055, which will be tested by Planck Satellite data. Our theory also creates a new picture of self-consistent quantum cosmological history. |
1808.03136 | Peter K.F. Kuhfittig | Peter K.F. Kuhfittig and Vance D. Gladney | A model for dark energy based on the theory of embedding | 8 pages, i figure | Advanced Studies in Theoretical Physics, vol. 12, no. 5, pp.
233-241 (2018) | 10.12988/astp.2018.8627 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A long-standing topic of interest in the general theory of relativity is the
embedding of curved spacetimes in higher-dimensional flat spacetimes. The main
purpose this paper is to show that the embedding theory can account for the
accelerated expansion of the Universe and thereby serve as a model for dark
energy. This result is consistent with earlier findings based on noncommutative
geometry. A secondary objective is to show that the embedding theory also
implies that it is possible, at least in principle, for the accelerated
expansion to reverse to become a deceleration.
| [
{
"created": "Thu, 9 Aug 2018 13:10:25 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Feb 2019 19:10:55 GMT",
"version": "v2"
},
{
"created": "Thu, 10 Jun 2021 14:27:28 GMT",
"version": "v3"
}
] | 2021-06-11 | [
[
"Kuhfittig",
"Peter K. F.",
""
],
[
"Gladney",
"Vance D.",
""
]
] | A long-standing topic of interest in the general theory of relativity is the embedding of curved spacetimes in higher-dimensional flat spacetimes. The main purpose this paper is to show that the embedding theory can account for the accelerated expansion of the Universe and thereby serve as a model for dark energy. This result is consistent with earlier findings based on noncommutative geometry. A secondary objective is to show that the embedding theory also implies that it is possible, at least in principle, for the accelerated expansion to reverse to become a deceleration. |
gr-qc/0411033 | Chang Jun Gao | Chang Jun Gao | Arbitrary Dimensional Schwarzschild-FRW Black Holes | 10 pages | Class.Quant.Grav. 21 (2004) 4805-4810 | 10.1088/0264-9381/21/21/004 | null | gr-qc astro-ph | null | The metric of arbitrary dimensional Schwarzschild black hole in the
background of Friedman-Robertson-Walker universe is presented in the cosmic
coordinates system. In particular, the arbitrary dimensional Schwarzschild-de
Sitter metric is rewritten in the Schwarzschild coordinates system and basing
on which the even more generalized higher dimensional Schwarzschild-de Sitter
metric with another extra dimensions is found. The generalized solution shows
that the cosmological constant may roots in the extra dimensions of space.
| [
{
"created": "Mon, 8 Nov 2004 01:56:59 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Nov 2004 09:09:05 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Gao",
"Chang Jun",
""
]
] | The metric of arbitrary dimensional Schwarzschild black hole in the background of Friedman-Robertson-Walker universe is presented in the cosmic coordinates system. In particular, the arbitrary dimensional Schwarzschild-de Sitter metric is rewritten in the Schwarzschild coordinates system and basing on which the even more generalized higher dimensional Schwarzschild-de Sitter metric with another extra dimensions is found. The generalized solution shows that the cosmological constant may roots in the extra dimensions of space. |
1510.05939 | Ayan Banerjee | Ayan Banerjee, Farook Rahaman, Sayeedul Islam and Megan Govender | Braneworld gravastars admitting conformal motion | 10 pages, no figures, minor changes, references added, Accepted in
Eur.Phys.J. C | null | 10.1140/epjc/s10052-016-3887-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we study the Mazur and Mottola gravastar model within the
context of Randall-Sundrum II type braneworld scenario, based on the fact that
our four dimensional space-time is a three-brane, embedded in a five
dimensional bulk. We present exact solutions of the modified field equations in
each of the three regions making up the gravastar, namely, (I) the core, (II)
the shell, and (III) the vacuum exterior. The junction conditions at each
interface are fulfilled and we further explore interesting physical properties
such as length and energy and entropy of the spherical distribution.
| [
{
"created": "Fri, 16 Oct 2015 15:14:05 GMT",
"version": "v1"
},
{
"created": "Sat, 9 Jan 2016 16:11:05 GMT",
"version": "v2"
}
] | 2016-02-17 | [
[
"Banerjee",
"Ayan",
""
],
[
"Rahaman",
"Farook",
""
],
[
"Islam",
"Sayeedul",
""
],
[
"Govender",
"Megan",
""
]
] | In this work, we study the Mazur and Mottola gravastar model within the context of Randall-Sundrum II type braneworld scenario, based on the fact that our four dimensional space-time is a three-brane, embedded in a five dimensional bulk. We present exact solutions of the modified field equations in each of the three regions making up the gravastar, namely, (I) the core, (II) the shell, and (III) the vacuum exterior. The junction conditions at each interface are fulfilled and we further explore interesting physical properties such as length and energy and entropy of the spherical distribution. |
2310.00437 | Alan Cesar Ms | Eduardo Bittencourt, Alan G. Cesar and Jonas P. Pereira | Feasibility of singularity avoidance for a collapsing object due to a
scalar field | 16 pages, 5 figures | JCAP12(2023)037 | 10.1088/1475-7516/2023/12/037 | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | We study the problem of the gravitational collapse of an object as seen by an
external observer. We assume that the resultant spacetime is a match of an
external Vaidya spacetime with an interior
Friedmann-Lema\^itre-Robertson-Walker (FRLW) spacetime of any spatial curvature
and with a scalar field both minimally and non-minimally coupled to the metric.
With the goal of studying a contracting (collapsing) object, for the initial
moment of observation we take that its energy density and pressure are
positive, that there are no trapping surfaces, and that the null energy
condition (NEC) and the strong energy condition (SEC) are fulfilled. We show
that there are many cases where singularities could be avoided for both the
minimal and non-minimal couplings, although the contexts for so are very
different in both cases. For the minimal coupling, the avoidance of
singularities could happen either through evaporation or altogether, triggered
by a violation of the SEC for a period of time. For the non-minimal coupling,
the complete singularity avoidance happens only if evaporation takes place, and
a temporary violation of the SEC does not thwart the formation of
singularities. The above results show the relevance of the global (the whole
spacetime) validity of energy conditions for the singularity theorems to be
applicable; otherwise, the fate of a collapsing star is not known a priori. At
the same time, the surface behavior of a collapsing body offers partial
diagnostics of what happens in the inaccessible regions of spacetime to
external observers. Our analyses suggest that a bounce behavior of the surface
of the initially collapsing object is a fingerprint of the SEC violation in its
interior, and that could be due to the existence of scalar fields there.
| [
{
"created": "Sat, 30 Sep 2023 17:21:32 GMT",
"version": "v1"
}
] | 2023-12-27 | [
[
"Bittencourt",
"Eduardo",
""
],
[
"Cesar",
"Alan G.",
""
],
[
"Pereira",
"Jonas P.",
""
]
] | We study the problem of the gravitational collapse of an object as seen by an external observer. We assume that the resultant spacetime is a match of an external Vaidya spacetime with an interior Friedmann-Lema\^itre-Robertson-Walker (FRLW) spacetime of any spatial curvature and with a scalar field both minimally and non-minimally coupled to the metric. With the goal of studying a contracting (collapsing) object, for the initial moment of observation we take that its energy density and pressure are positive, that there are no trapping surfaces, and that the null energy condition (NEC) and the strong energy condition (SEC) are fulfilled. We show that there are many cases where singularities could be avoided for both the minimal and non-minimal couplings, although the contexts for so are very different in both cases. For the minimal coupling, the avoidance of singularities could happen either through evaporation or altogether, triggered by a violation of the SEC for a period of time. For the non-minimal coupling, the complete singularity avoidance happens only if evaporation takes place, and a temporary violation of the SEC does not thwart the formation of singularities. The above results show the relevance of the global (the whole spacetime) validity of energy conditions for the singularity theorems to be applicable; otherwise, the fate of a collapsing star is not known a priori. At the same time, the surface behavior of a collapsing body offers partial diagnostics of what happens in the inaccessible regions of spacetime to external observers. Our analyses suggest that a bounce behavior of the surface of the initially collapsing object is a fingerprint of the SEC violation in its interior, and that could be due to the existence of scalar fields there. |
1701.06902 | H\'el\`ene Pihan-Le Bars | H. Pihan-Le Bars and C. Guerlin and Q.G. Bailey and S. Bize and P.
Wolf | Improved Tests of Lorentz Invariance in the Matter Sector using Atomic
Clocks | null | null | null | null | gr-qc hep-ex | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For the purpose of searching for Lorentz-invariance violation in the minimal
Standard-Model Extension, we perfom a reanalysis of data obtained from the
$^{133}\text{Cs}$ fountain clock operating at SYRTE. The previous study led to
new limits on eight components of the $\tilde{c}_{\mu\nu}$ tensor, which
quantifies the anisotropy of the proton kinetic energy. We recently derived an
advanced model for the frequency shift of hyperfine Zeeman transition due to
Lorentz violation and became able to constrain the ninth component, the
isotropic coefficient $\tilde{c}_{TT}$, which is the least well-constrained
coefficient of $\tilde{c}_{\mu\nu}$. This model is based on a second-order
boost Lorentz transformation from the laboratory frame to the Sun-centered
frame, and it gives rise to an improvement of five orders of magnitude on
$\tilde{c}_{TT}$ compared to the state of the art.
| [
{
"created": "Thu, 19 Jan 2017 22:50:03 GMT",
"version": "v1"
}
] | 2017-01-25 | [
[
"Bars",
"H. Pihan-Le",
""
],
[
"Guerlin",
"C.",
""
],
[
"Bailey",
"Q. G.",
""
],
[
"Bize",
"S.",
""
],
[
"Wolf",
"P.",
""
]
] | For the purpose of searching for Lorentz-invariance violation in the minimal Standard-Model Extension, we perfom a reanalysis of data obtained from the $^{133}\text{Cs}$ fountain clock operating at SYRTE. The previous study led to new limits on eight components of the $\tilde{c}_{\mu\nu}$ tensor, which quantifies the anisotropy of the proton kinetic energy. We recently derived an advanced model for the frequency shift of hyperfine Zeeman transition due to Lorentz violation and became able to constrain the ninth component, the isotropic coefficient $\tilde{c}_{TT}$, which is the least well-constrained coefficient of $\tilde{c}_{\mu\nu}$. This model is based on a second-order boost Lorentz transformation from the laboratory frame to the Sun-centered frame, and it gives rise to an improvement of five orders of magnitude on $\tilde{c}_{TT}$ compared to the state of the art. |
2108.05210 | Fredy Dubeibe | F. L. Dubeibe, Tareq Saeed, and Euaggelos E. Zotos | Effect of Multipole Moments in the Weak Field Limit of a Black Hole Plus
Halo Potential | 10 pages, 7 figures | The Astrophysical Journal, 908:74, (2021) | 10.3847/1538-4357/abcd9f | null | gr-qc nlin.CD | http://creativecommons.org/licenses/by/4.0/ | In this paper, we consider a Newtonian system whose relativistic counterpart
describes a superimposed halo with a black hole. Our aim is to determine how
the quadrupole and octupole moments affect the nature of the motion of a test
particle, moving in the close vicinity of the black hole. The different types
of trajectories for the test particle are mainly classified as bounded,
collisional, and escaping, by using modern color-coded basin diagrams.
Moreover, an additional analysis is carried out for distinguishing between the
different types of bounded motion (regular, sticky, and chaotic). Our results
strongly indicate that the multipole moments, along with the total orbital
energy, highly affect the final state of the test particle, while at the same
time the basin geometry of the phase space tends to be highly dominated by
collision and escape orbits.
| [
{
"created": "Wed, 11 Aug 2021 13:19:12 GMT",
"version": "v1"
}
] | 2021-08-12 | [
[
"Dubeibe",
"F. L.",
""
],
[
"Saeed",
"Tareq",
""
],
[
"Zotos",
"Euaggelos E.",
""
]
] | In this paper, we consider a Newtonian system whose relativistic counterpart describes a superimposed halo with a black hole. Our aim is to determine how the quadrupole and octupole moments affect the nature of the motion of a test particle, moving in the close vicinity of the black hole. The different types of trajectories for the test particle are mainly classified as bounded, collisional, and escaping, by using modern color-coded basin diagrams. Moreover, an additional analysis is carried out for distinguishing between the different types of bounded motion (regular, sticky, and chaotic). Our results strongly indicate that the multipole moments, along with the total orbital energy, highly affect the final state of the test particle, while at the same time the basin geometry of the phase space tends to be highly dominated by collision and escape orbits. |
gr-qc/9704055 | S. Antoci | S. Antoci and L. Mihich | A forgotten argument by Gordon uniquely selects Abraham's tensor as the
energy-momentum tensor for the electromagnetic field in homogeneous,
isotropic matter | Plain TeX, 9 pages, no figures, to appear in Nuovo Cimento B | Nuovo Cim. B112 (1997) 991-1001 | null | null | gr-qc physics.class-ph | null | Given the present status of the problem of the electromagnetic energy tensor
in matter, there is perhaps use in recalling a forgotten argument given in 1923
by W. Gordon. Let us consider a material medium which is homogeneous and
isotropic when viewed in its rest frame. For such a medium, Gordon's argument
allows to reduce the above mentioned problem to an analogous one, defined in a
general relativistic vacuum, in presence of a suitably determined effective
metric. For the latter problem the form of the Lagrangian is known already,
hence the determination of the energy tensor is a straightforward matter. One
just performs the Hamiltonian derivative of the Lagrangian chosen in this way
with respect to the true metric. Abraham's tensor is thus selected as the
electromagnetic energy tensor for a medium which is homogeneous and isotropic
in its rest frame.
| [
{
"created": "Mon, 21 Apr 1997 18:50:40 GMT",
"version": "v1"
}
] | 2008-02-03 | [
[
"Antoci",
"S.",
""
],
[
"Mihich",
"L.",
""
]
] | Given the present status of the problem of the electromagnetic energy tensor in matter, there is perhaps use in recalling a forgotten argument given in 1923 by W. Gordon. Let us consider a material medium which is homogeneous and isotropic when viewed in its rest frame. For such a medium, Gordon's argument allows to reduce the above mentioned problem to an analogous one, defined in a general relativistic vacuum, in presence of a suitably determined effective metric. For the latter problem the form of the Lagrangian is known already, hence the determination of the energy tensor is a straightforward matter. One just performs the Hamiltonian derivative of the Lagrangian chosen in this way with respect to the true metric. Abraham's tensor is thus selected as the electromagnetic energy tensor for a medium which is homogeneous and isotropic in its rest frame. |
1803.00172 | Pablo Antonio Cano Molina-Ni\~nirola | Pablo A. Cano | Lovelock action with nonsmooth boundaries | 33 pages, 2 figures; version published in PRD; few additional typos
corrected | Phys. Rev. D 97, 104048 (2018) | 10.1103/PhysRevD.97.104048 | IFT-UAM/CSIC-18-020 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the variational problem in Lovelock gravity when the boundary
contains timelike and spacelike segments nonsmoothly glued. We show that two
kinds of contributions have to be added to the action. The first one is
associated to the presence of a boundary in every segment and it depends on
intrinsic and extrinsic curvatures. We can think of this contribution as adding
a total derivative to the usual surface term of Lovelock gravity. The second
one appears in every joint between two segments and it involves the integral
along the joint of the Jacobson-Myers entropy density weighted by the Lorentz
boost parameter which relates the orthonormal frames in each segment. We argue
that this term can be straightforwardly extended to the case of joints
involving null boundaries. As an application, we compute the contribution of
these terms to the complexity of global AdS in Lovelock gravity by using the
"complexity = action" proposal and we identify possible universal terms for
arbitrary values of the Lovelock couplings. We find that they depend on the
charge $a^*$ controlling the holographic entanglement entropy and on a new
constant that we characterize.
| [
{
"created": "Thu, 1 Mar 2018 02:27:45 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Mar 2018 17:26:44 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Oct 2018 10:39:00 GMT",
"version": "v3"
}
] | 2018-10-09 | [
[
"Cano",
"Pablo A.",
""
]
] | We examine the variational problem in Lovelock gravity when the boundary contains timelike and spacelike segments nonsmoothly glued. We show that two kinds of contributions have to be added to the action. The first one is associated to the presence of a boundary in every segment and it depends on intrinsic and extrinsic curvatures. We can think of this contribution as adding a total derivative to the usual surface term of Lovelock gravity. The second one appears in every joint between two segments and it involves the integral along the joint of the Jacobson-Myers entropy density weighted by the Lorentz boost parameter which relates the orthonormal frames in each segment. We argue that this term can be straightforwardly extended to the case of joints involving null boundaries. As an application, we compute the contribution of these terms to the complexity of global AdS in Lovelock gravity by using the "complexity = action" proposal and we identify possible universal terms for arbitrary values of the Lovelock couplings. We find that they depend on the charge $a^*$ controlling the holographic entanglement entropy and on a new constant that we characterize. |
1711.05693 | Deepak Vaid | Deepak Vaid | Connecting Loop Quantum Gravity and String Theory via Quantum Geometry | v1: A slightly modified version of this paper ws submitted to the
"Beyond Spacetime" 2017 essay contest on Sep 25, 2017, v2: references
updated, improved layout v3: added section on Immirzi parameter, expanded
conclusion, prepared for Submission to SciPost | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by-sa/4.0/ | We argue that String Theory and Loop Quantum Gravity can be thought of as
describing different regimes of a single unified theory of quantum gravity. LQG
can be thought of as providing the pre-geometric exoskeleton out of which
macroscopic geometry emerges and String Theory then becomes the
\emph{effective} theory which describes the dynamics of that exoskeleton. The
core of the argument rests on the claim that the Nambu-Goto action of String
Theory can be viewed as the expectation value of the LQG area operator
evaluated on the string worldsheet. A concrete result is that the string
tension of String Theory and the Barbero-Immirzi parameter of LQG turn out to
be proportional to each other.
| [
{
"created": "Wed, 15 Nov 2017 17:40:58 GMT",
"version": "v1"
},
{
"created": "Sun, 19 Nov 2017 17:35:16 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Jan 2018 09:46:53 GMT",
"version": "v3"
}
] | 2018-01-09 | [
[
"Vaid",
"Deepak",
""
]
] | We argue that String Theory and Loop Quantum Gravity can be thought of as describing different regimes of a single unified theory of quantum gravity. LQG can be thought of as providing the pre-geometric exoskeleton out of which macroscopic geometry emerges and String Theory then becomes the \emph{effective} theory which describes the dynamics of that exoskeleton. The core of the argument rests on the claim that the Nambu-Goto action of String Theory can be viewed as the expectation value of the LQG area operator evaluated on the string worldsheet. A concrete result is that the string tension of String Theory and the Barbero-Immirzi parameter of LQG turn out to be proportional to each other. |
1202.6289 | P\'eter Kov\'acs Dr. | P. Forg\'acs, T. Herpay, P. Kov\'acs | Comment on "Finite Size Corrections to the Radiation Reaction Force in
Classical Electrodynamics" [arXiv:1005.2617] | 1 page | null | 10.1103/PhysRevLett.109.029501 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In [1, arXiv:1005.2617] effective field theory methods have been employed to
compute the equations of motion of a spherically symmetric charged shell of
radius R, taking into account the radiation reaction force exerted by the
shell's own electromagnetic field up to O(R^2). The authors of Ref. [1] have
stated that the known result for the self force of the shell as can be found
from Eq. (16.28) of the textbook of Jackson [2] (see also Chap. 4 in the review
of Pearle [3]) is incorrect, in that the term linear in R should be absent. We
claim that this conclusion of Ref. [1] is incorrect, and that the textbook
result, Eq. (1) does hold.
| [
{
"created": "Tue, 28 Feb 2012 17:10:38 GMT",
"version": "v1"
}
] | 2015-06-04 | [
[
"Forgács",
"P.",
""
],
[
"Herpay",
"T.",
""
],
[
"Kovács",
"P.",
""
]
] | In [1, arXiv:1005.2617] effective field theory methods have been employed to compute the equations of motion of a spherically symmetric charged shell of radius R, taking into account the radiation reaction force exerted by the shell's own electromagnetic field up to O(R^2). The authors of Ref. [1] have stated that the known result for the self force of the shell as can be found from Eq. (16.28) of the textbook of Jackson [2] (see also Chap. 4 in the review of Pearle [3]) is incorrect, in that the term linear in R should be absent. We claim that this conclusion of Ref. [1] is incorrect, and that the textbook result, Eq. (1) does hold. |
1002.4230 | Hao Wei | Hao Wei | Spinor Dark Energy and Cosmological Coincidence Problem | 9 pages, revtex4; v2: major revision, title changed, Phys. Lett. B in
press; v3: published version | Phys.Lett.B695:307-311,2011 | 10.1016/j.physletb.2010.10.053 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, the so-called Elko spinor field has been proposed to be a candidate
of dark energy. It is a non-standard spinor and has unusual properties. When
the Elko spinor field is used in cosmology, its unusual properties could bring
some interesting consequences. In the present work, we discuss the cosmological
coincidence problem in the spinor dark energy models by using the dynamical
system method. Our results show that the cosmological coincidence problem
should be taken to heart in the investigations of spinor dark energy models.
| [
{
"created": "Tue, 23 Feb 2010 07:31:00 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Oct 2010 07:00:00 GMT",
"version": "v2"
},
{
"created": "Mon, 20 Dec 2010 08:43:00 GMT",
"version": "v3"
}
] | 2010-12-21 | [
[
"Wei",
"Hao",
""
]
] | Recently, the so-called Elko spinor field has been proposed to be a candidate of dark energy. It is a non-standard spinor and has unusual properties. When the Elko spinor field is used in cosmology, its unusual properties could bring some interesting consequences. In the present work, we discuss the cosmological coincidence problem in the spinor dark energy models by using the dynamical system method. Our results show that the cosmological coincidence problem should be taken to heart in the investigations of spinor dark energy models. |
1401.5819 | Matti Raasakka | Daniele Oriti and Matti Raasakka | Asymptotic Analysis of the Ponzano-Regge Model with Non-Commutative
Metric Boundary Data | null | SIGMA 10 (2014), 067, 32 pages | 10.3842/SIGMA.2014.067 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/3.0/ | We apply the non-commutative Fourier transform for Lie groups to formulate
the non-commutative metric representation of the Ponzano-Regge spin foam model
for 3d quantum gravity. The non-commutative representation allows to express
the amplitudes of the model as a first order phase space path integral, whose
properties we consider. In particular, we study the asymptotic behavior of the
path integral in the semi-classical limit. First, we compare the stationary
phase equations in the classical limit for three different non-commutative
structures corresponding to the symmetric, Duflo and Freidel-Livine-Majid
quantization maps. We find that in order to unambiguously recover discrete
geometric constraints for non-commutative metric boundary data through the
stationary phase method, the deformation structure of the phase space must be
accounted for in the variational calculus. When this is understood, our results
demonstrate that the non-commutative metric representation facilitates a
convenient semi-classical analysis of the Ponzano-Regge model, which yields as
the dominant contribution to the amplitude the cosine of the Regge action in
agreement with previous studies. We also consider the asymptotics of the ${\rm
SU}(2)$ $6j$-symbol using the non-commutative phase space path integral for the
Ponzano-Regge model, and explain the connection of our results to the previous
asymptotic results in terms of coherent states.
| [
{
"created": "Wed, 22 Jan 2014 22:28:56 GMT",
"version": "v1"
},
{
"created": "Thu, 15 May 2014 10:24:08 GMT",
"version": "v2"
},
{
"created": "Thu, 26 Jun 2014 04:58:24 GMT",
"version": "v3"
}
] | 2014-06-27 | [
[
"Oriti",
"Daniele",
""
],
[
"Raasakka",
"Matti",
""
]
] | We apply the non-commutative Fourier transform for Lie groups to formulate the non-commutative metric representation of the Ponzano-Regge spin foam model for 3d quantum gravity. The non-commutative representation allows to express the amplitudes of the model as a first order phase space path integral, whose properties we consider. In particular, we study the asymptotic behavior of the path integral in the semi-classical limit. First, we compare the stationary phase equations in the classical limit for three different non-commutative structures corresponding to the symmetric, Duflo and Freidel-Livine-Majid quantization maps. We find that in order to unambiguously recover discrete geometric constraints for non-commutative metric boundary data through the stationary phase method, the deformation structure of the phase space must be accounted for in the variational calculus. When this is understood, our results demonstrate that the non-commutative metric representation facilitates a convenient semi-classical analysis of the Ponzano-Regge model, which yields as the dominant contribution to the amplitude the cosine of the Regge action in agreement with previous studies. We also consider the asymptotics of the ${\rm SU}(2)$ $6j$-symbol using the non-commutative phase space path integral for the Ponzano-Regge model, and explain the connection of our results to the previous asymptotic results in terms of coherent states. |
0708.1408 | Xin Zhang | Xin Zhang | Can black holes be torn up by phantom dark energy in cyclic cosmology? | 6 pages, 2 figures; discussions added | Eur.Phys.J.C60:661-667,2009 | 10.1140/epjc/s10052-009-0967-5 | null | gr-qc astro-ph hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Infinitely cyclic cosmology is often frustrated by the black hole problem. It
has been speculated that this obstacle in cyclic cosmology can be removed by
taking into account a peculiar cyclic model derived from loop quantum cosmology
or the braneworld scenario, in which phantom dark energy plays a crucial role.
In this peculiar cyclic model, the mechanism of solving the black hole problem
is through tearing up black holes by phantom. However, using the theory of
fluid accretion onto black holes, we show in this paper that there exists
another possibility: that black holes cannot be torn up by phantom in this
cyclic model. We discussed this possibility and showed that the masses of black
holes might first decrease and then increase, through phantom accretion onto
black holes in the expanding stage of the cyclic universe.
| [
{
"created": "Fri, 10 Aug 2007 12:02:36 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Nov 2007 12:37:24 GMT",
"version": "v2"
},
{
"created": "Tue, 10 Mar 2009 10:01:14 GMT",
"version": "v3"
}
] | 2009-04-24 | [
[
"Zhang",
"Xin",
""
]
] | Infinitely cyclic cosmology is often frustrated by the black hole problem. It has been speculated that this obstacle in cyclic cosmology can be removed by taking into account a peculiar cyclic model derived from loop quantum cosmology or the braneworld scenario, in which phantom dark energy plays a crucial role. In this peculiar cyclic model, the mechanism of solving the black hole problem is through tearing up black holes by phantom. However, using the theory of fluid accretion onto black holes, we show in this paper that there exists another possibility: that black holes cannot be torn up by phantom in this cyclic model. We discussed this possibility and showed that the masses of black holes might first decrease and then increase, through phantom accretion onto black holes in the expanding stage of the cyclic universe. |
1312.7590 | Gabriel Leon | Gabriel Leon and Daniel Sudarsky | Origin of Structure: Primordial Bispectrum without non-Gaussianities | 27 pages. The model considered in this work, although conceptual and
technically correct, yields predictions that are the same as the standard
inflationary scenario. The interested readers are encouraged to consult
arXiv:1503.01417 for an updated version of this paper in which
distinguishable predictions are made | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The primordial bispectrum has been considered in the past decade as a
powerful probe of the physical processes taking place in the early Universe.
Within the inflationary paradigm, the properties of the bispectrum are one of
the keys that serves to discriminate among competing scenarios concerning the
details of the origin of cosmological perturbations. However, all of the
scenarios, based on the conventional approach to the so-called
"quantum-to-classical transition" during inflation, lack the ability to point
out the precise physical mechanism responsible for generating the inhomogeneity
and anisotropy of our Universe starting from and exactly homogeneous and
isotropic vacuum state associated with the early inflationary regime. In past
works, we have shown that the proposals involving a spontaneous dynamical
reduction of the quantum state provide plausible explanations for the birth of
said primordial inhomogeneities and anisotropies. In the present letter, we
show that, when considering single-field slow-roll inflation within the context
of such proposals, the expected characteristics of the bispectrum turn out to
be quite different from those found in the traditional approach. In particular,
the statistical features corresponding to the primordial perturbations, which
are normally associated with the bispectrum, are treated here in a novel way
leading to rather different conclusions.
| [
{
"created": "Sun, 29 Dec 2013 21:12:34 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Jan 2014 07:37:46 GMT",
"version": "v2"
},
{
"created": "Fri, 6 Mar 2015 01:33:42 GMT",
"version": "v3"
}
] | 2015-03-09 | [
[
"Leon",
"Gabriel",
""
],
[
"Sudarsky",
"Daniel",
""
]
] | The primordial bispectrum has been considered in the past decade as a powerful probe of the physical processes taking place in the early Universe. Within the inflationary paradigm, the properties of the bispectrum are one of the keys that serves to discriminate among competing scenarios concerning the details of the origin of cosmological perturbations. However, all of the scenarios, based on the conventional approach to the so-called "quantum-to-classical transition" during inflation, lack the ability to point out the precise physical mechanism responsible for generating the inhomogeneity and anisotropy of our Universe starting from and exactly homogeneous and isotropic vacuum state associated with the early inflationary regime. In past works, we have shown that the proposals involving a spontaneous dynamical reduction of the quantum state provide plausible explanations for the birth of said primordial inhomogeneities and anisotropies. In the present letter, we show that, when considering single-field slow-roll inflation within the context of such proposals, the expected characteristics of the bispectrum turn out to be quite different from those found in the traditional approach. In particular, the statistical features corresponding to the primordial perturbations, which are normally associated with the bispectrum, are treated here in a novel way leading to rather different conclusions. |
1206.1320 | George Chapline F | George Chapline | Can a closed critical surface in a quark-gluon plasma serve as a model
for the behavior of quantum gravity near to an event horizon? | 11 pages, 1 figure | null | null | null | gr-qc hep-th nucl-ex | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Time stands still at a quantum critical point in the sense that correlation
functions near to the critical point are approximately independent of
frequency. In the case of a quantum liquid this would imply that classical
hydrodynamics breaks down near to the critical point, revealing the underlying
quantum degrees of freedom. An opportunity to see this effect for the first
time in the laboratory may be provided by relativistic heavy ion collisions
that are tuned so that the quark-gluon plasma passes through its critical point
forming a closed critical surface. In this note we point out that in certain
kinds of quantum fluids the temperature of a spherical critical surface will be
proportional to (radius)-1 and the entropy inside the surface will be close to
the Bekenstein bound. In these cases the breakdown in hydrodynamics near to the
critical point might serve as a model for the behavior of quantum gravity near
to an event horizon. Such a possibility is a fortiori notable because general
relativity predicts that nothing should happen at an event horizon.
| [
{
"created": "Tue, 5 Jun 2012 22:44:32 GMT",
"version": "v1"
}
] | 2012-06-08 | [
[
"Chapline",
"George",
""
]
] | Time stands still at a quantum critical point in the sense that correlation functions near to the critical point are approximately independent of frequency. In the case of a quantum liquid this would imply that classical hydrodynamics breaks down near to the critical point, revealing the underlying quantum degrees of freedom. An opportunity to see this effect for the first time in the laboratory may be provided by relativistic heavy ion collisions that are tuned so that the quark-gluon plasma passes through its critical point forming a closed critical surface. In this note we point out that in certain kinds of quantum fluids the temperature of a spherical critical surface will be proportional to (radius)-1 and the entropy inside the surface will be close to the Bekenstein bound. In these cases the breakdown in hydrodynamics near to the critical point might serve as a model for the behavior of quantum gravity near to an event horizon. Such a possibility is a fortiori notable because general relativity predicts that nothing should happen at an event horizon. |
1904.04743 | Avadhut Purohit | Avadhut V Purohit | The scalar field and gravity combined variable in ADM theory | 13 pages, 1 graph | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The canonical theory of gravity together with the scalar field is written as
a combined variable theory in ADM form, in the classical and quantum theory.
FLRW $\kappa = 0$ cosmology is rewritten in the combined variable theory.
| [
{
"created": "Tue, 9 Apr 2019 15:45:55 GMT",
"version": "v1"
},
{
"created": "Wed, 1 May 2019 17:07:48 GMT",
"version": "v2"
},
{
"created": "Sun, 14 Jul 2019 18:08:13 GMT",
"version": "v3"
}
] | 2019-07-16 | [
[
"Purohit",
"Avadhut V",
""
]
] | The canonical theory of gravity together with the scalar field is written as a combined variable theory in ADM form, in the classical and quantum theory. FLRW $\kappa = 0$ cosmology is rewritten in the combined variable theory. |
2112.11300 | Mark Hannam | Mark Hannam, Charlie Hoy, Jonathan E. Thompson, Stephen Fairhurst,
Vivien Raymond, Marta Colleoni, Derek Davis, H\'ector Estell\'es, Carl-Johan
Haster, Adrian Helmling-Cornell, Sascha Husa, David Keitel, T. J. Massinger,
Alexis Men\'endez-V\'azquez, Kentaro Mogushi, Serguei Ossokine, Ethan Payne,
Geraint Pratten, Isobel Romero-Shaw, Jam Sadiq, Patricia Schmidt, Rodrigo
Tenorio, Richard Udall, John Veitch, Daniel Williams, Anjali Balasaheb
Yelikar, Aaron Zimmerman | General-relativistic precession in a black-hole binary | 16 pages, 6 figures. Update to match published version | Nature 610 (2022) 7933, 652-655 | 10.1038/s41586-022-05212-z | LIGO-P2100452 | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | The general-relativistic phenomenon of spin-induced orbital precession has
not yet been observed in strong-field gravity. Gravitational-wave observations
of binary black holes (BBHs) are prime candidates, since we expect the
astrophysical binary population to contain precessing binaries. Imprints of
precession have been investigated in several signals, but no definitive
identification of orbital precession has been reported in any one of the 84 BBH
observations to date by the Advanced LIGO and Virgo detectors. Here we report
the measurement of strong-field precession in the LIGO-Virgo-Kagra (LVK)
gravitational-wave signal GW200129. The binary's orbit precesses at a rate ten
orders of magnitude faster than previous weak-field measurements from binary
pulsars. We also find that the primary black hole is likely highly spinning.
According to current binary population estimates a GW200129-like signal is
extremely unlikely, and therefore presents a direct challenge to many current
binary formation models.
| [
{
"created": "Tue, 21 Dec 2021 15:42:07 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Oct 2022 16:07:50 GMT",
"version": "v2"
},
{
"created": "Mon, 17 Oct 2022 08:23:02 GMT",
"version": "v3"
},
{
"created": "Wed, 31 May 2023 19:50:14 GMT",
"version": "v4"
}
] | 2023-06-02 | [
[
"Hannam",
"Mark",
""
],
[
"Hoy",
"Charlie",
""
],
[
"Thompson",
"Jonathan E.",
""
],
[
"Fairhurst",
"Stephen",
""
],
[
"Raymond",
"Vivien",
""
],
[
"Colleoni",
"Marta",
""
],
[
"Davis",
"Derek",
""
],
[... | The general-relativistic phenomenon of spin-induced orbital precession has not yet been observed in strong-field gravity. Gravitational-wave observations of binary black holes (BBHs) are prime candidates, since we expect the astrophysical binary population to contain precessing binaries. Imprints of precession have been investigated in several signals, but no definitive identification of orbital precession has been reported in any one of the 84 BBH observations to date by the Advanced LIGO and Virgo detectors. Here we report the measurement of strong-field precession in the LIGO-Virgo-Kagra (LVK) gravitational-wave signal GW200129. The binary's orbit precesses at a rate ten orders of magnitude faster than previous weak-field measurements from binary pulsars. We also find that the primary black hole is likely highly spinning. According to current binary population estimates a GW200129-like signal is extremely unlikely, and therefore presents a direct challenge to many current binary formation models. |
2309.07404 | LiFang Li | Xin-Yun Hu, Xiao-Xiong Zeng, Li-Fang Li, Peng Xu | Holographic Einstein rings of Non-commutative black holes | many figures. arXiv admin note: text overlap with arXiv:1811.12617 by
other authors | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | With the help of the AdS/CFT correspondence, we easily derive the desired
response function of QFT on the boundary. Using the virtual optical system with
a convex lens, we are able to obtain the image of the black hole from the
response function and further study the Einstein ring of the non-commutative
black holes. All the results show that there are some common features and
different features compared to the previous study of other background black
holes. And with the change of the observation position, this ring will change
into a luminosity-deformed ring, or light points. In addition to these
similarities, there are some different features which are due to the
singularity of the event horizon temperature. Explicitly, the relation between
temperature and the event horizon $T-z_h$ has two branches when the
non-commutative parameter $n$ is fixed. These in turn have an effect on the
behavior of the response function and the Einstein ring. However, the amplitude
of $|\langle O\rangle|$ increases with the decrease of the temperature $T$ for
the left branch of $T-z_h$ relation, while the amplitude of $|\langle
O\rangle|$ decreases with the decrease of the temperature $T$ for the right
branch. These differences are also reflected in the Einstein ring. Therefore,
these differences can be used to distinguish different black hole backgrounds.
Furthermore, we show that the non-commutative parameter has an effect on the
brightness and the position of Einstein ring.
| [
{
"created": "Thu, 14 Sep 2023 03:16:22 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Sep 2023 06:51:42 GMT",
"version": "v2"
},
{
"created": "Fri, 22 Sep 2023 05:30:01 GMT",
"version": "v3"
},
{
"created": "Fri, 15 Dec 2023 14:24:29 GMT",
"version": "v4"
},
{
"c... | 2023-12-29 | [
[
"Hu",
"Xin-Yun",
""
],
[
"Zeng",
"Xiao-Xiong",
""
],
[
"Li",
"Li-Fang",
""
],
[
"Xu",
"Peng",
""
]
] | With the help of the AdS/CFT correspondence, we easily derive the desired response function of QFT on the boundary. Using the virtual optical system with a convex lens, we are able to obtain the image of the black hole from the response function and further study the Einstein ring of the non-commutative black holes. All the results show that there are some common features and different features compared to the previous study of other background black holes. And with the change of the observation position, this ring will change into a luminosity-deformed ring, or light points. In addition to these similarities, there are some different features which are due to the singularity of the event horizon temperature. Explicitly, the relation between temperature and the event horizon $T-z_h$ has two branches when the non-commutative parameter $n$ is fixed. These in turn have an effect on the behavior of the response function and the Einstein ring. However, the amplitude of $|\langle O\rangle|$ increases with the decrease of the temperature $T$ for the left branch of $T-z_h$ relation, while the amplitude of $|\langle O\rangle|$ decreases with the decrease of the temperature $T$ for the right branch. These differences are also reflected in the Einstein ring. Therefore, these differences can be used to distinguish different black hole backgrounds. Furthermore, we show that the non-commutative parameter has an effect on the brightness and the position of Einstein ring. |
1305.5984 | Ali Shojai | F. Shojai, R. Moti and F. Najdat | Tracker coupled quintessence | 8 figures | Phys. Rev. D. 87, 043007, 2013 | 10.1103/PhysRevD.87.043007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper two tracker solutions for conformally coupled quintessence
model is obtained. The first solution is determined by dividing the evolution
of the universe to matter and dark energy dominated epochs and then the allowed
bound on the equation of state parameter is obtained, such that a tracker
behaviour is resulted. For the other solution, the quintessence potential is
assumed to be a linear combination of two exponential functions. Then we have
found an exact solution which can be tracker by adjusting some parameters.
| [
{
"created": "Sun, 26 May 2013 03:23:05 GMT",
"version": "v1"
}
] | 2015-06-16 | [
[
"Shojai",
"F.",
""
],
[
"Moti",
"R.",
""
],
[
"Najdat",
"F.",
""
]
] | In this paper two tracker solutions for conformally coupled quintessence model is obtained. The first solution is determined by dividing the evolution of the universe to matter and dark energy dominated epochs and then the allowed bound on the equation of state parameter is obtained, such that a tracker behaviour is resulted. For the other solution, the quintessence potential is assumed to be a linear combination of two exponential functions. Then we have found an exact solution which can be tracker by adjusting some parameters. |
2210.10948 | Yiqian Chen | Yiqian Chen, Peng Wang, Houwen Wu, Haitang Yang | Observational Appearance of a Freely-falling Star in an Asymmetric
Thin-shell Wormhole | 26 pages, 8 figures. arXiv admin note: substantial text overlap with
arXiv:2206.13705 | null | 10.1140/epjc/s10052-023-11486-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been recently reported that, at late times, the total luminosity of a
star freely falling in black holes decays exponentially with time, and one or
two series of flashes with decreasing intensity are seen by a specific
observer, depending on the number of photon spheres. In this paper, we examine
observational appearances of an infalling star in a reflection-asymmetric
wormhole, which has two photon spheres, one on each side of the wormhole. We
find that the late-time total luminosity measured by distant observers
gradually decays with time or remains roughly constant due to the absence of
the event horizon. Moreover, a specific observer would detect a couple of light
flashes in a bright background at late times. These observations would offer a
new tool to distinguish wormholes from black holes, even those with multiple
photon spheres.
| [
{
"created": "Thu, 20 Oct 2022 01:36:25 GMT",
"version": "v1"
}
] | 2023-05-24 | [
[
"Chen",
"Yiqian",
""
],
[
"Wang",
"Peng",
""
],
[
"Wu",
"Houwen",
""
],
[
"Yang",
"Haitang",
""
]
] | It has been recently reported that, at late times, the total luminosity of a star freely falling in black holes decays exponentially with time, and one or two series of flashes with decreasing intensity are seen by a specific observer, depending on the number of photon spheres. In this paper, we examine observational appearances of an infalling star in a reflection-asymmetric wormhole, which has two photon spheres, one on each side of the wormhole. We find that the late-time total luminosity measured by distant observers gradually decays with time or remains roughly constant due to the absence of the event horizon. Moreover, a specific observer would detect a couple of light flashes in a bright background at late times. These observations would offer a new tool to distinguish wormholes from black holes, even those with multiple photon spheres. |
gr-qc/0301010 | Yoshiaki Himemoto | Takahiro Tanaka and Yoshiaki Himemoto | Generation of dark radiation in the bulk inflaton model | 7 pages, no figures, references added, presentation improved, final
version to be published in PRD | Phys.Rev.D67:104007,2003 | 10.1103/PhysRevD.67.104007 | null | gr-qc astro-ph hep-ph hep-th | null | We investigate the dynamics of a bulk scalar field with various decay
channels in the Randall-Sundrum infinite braneworld scenario. A bulk scalar
field in this scenario has a quasi-localized mode which dominates the late-time
behavior near the brane. As for this mode, an interesting point is the presence
of dissipation caused by the escape of the energy in the direction away from
the brane, even if the bulk scalar field does not have the interaction with the
other bulk fields in the bulk and fields on the brane. We can interpret that
this lost energy is transfered to the dark radiation. We show that such an
effective 4-dimensional description for a bulk scalar field is valid including
the various processes of energy dissipation.
| [
{
"created": "Sun, 5 Jan 2003 13:45:06 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Mar 2003 08:39:20 GMT",
"version": "v2"
},
{
"created": "Mon, 21 Apr 2003 05:41:50 GMT",
"version": "v3"
}
] | 2014-11-17 | [
[
"Tanaka",
"Takahiro",
""
],
[
"Himemoto",
"Yoshiaki",
""
]
] | We investigate the dynamics of a bulk scalar field with various decay channels in the Randall-Sundrum infinite braneworld scenario. A bulk scalar field in this scenario has a quasi-localized mode which dominates the late-time behavior near the brane. As for this mode, an interesting point is the presence of dissipation caused by the escape of the energy in the direction away from the brane, even if the bulk scalar field does not have the interaction with the other bulk fields in the bulk and fields on the brane. We can interpret that this lost energy is transfered to the dark radiation. We show that such an effective 4-dimensional description for a bulk scalar field is valid including the various processes of energy dissipation. |
1009.0982 | Sushant Ghosh Prof | Sushant G. Ghosh and Naresh Dadhich | Radiating black holes in Einstein-Yang-Mills theory and cosmic
censorship | 9 RevTeX pages, 1 figure | Phys.Rev.D82:044038,2010 | 10.1103/PhysRevD.82.044038 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Exact nonstatic spherically symmetric black-hole solution of the higher
dimensional Einstein-Yang-Mills equations for a null dust with Yang-Mills gauge
charge are obtained by employing Wu-Yang \textit{ansatz}, namely, HD-EYM Vaidya
solution. It is interesting to note that gravitational contribution of YM gauge
charge for this ansatz is indeed opposite (attractive rather than repulsive)
that of Maxwell charge. It turns out that the gravitational collapse of null
dust with YM gauge charge admit strong curvature shell focusing naked
singularities violating cosmic censorship. However, there is significant
shrinkage of the initial data space for a naked singularity of the HD-Vaidya
collapse due to presence of YM gauge charge. The effect of YM gauge charge on
structure and location of the apparent and event horizons is also discussed.
| [
{
"created": "Mon, 6 Sep 2010 07:41:53 GMT",
"version": "v1"
}
] | 2011-11-10 | [
[
"Ghosh",
"Sushant G.",
""
],
[
"Dadhich",
"Naresh",
""
]
] | Exact nonstatic spherically symmetric black-hole solution of the higher dimensional Einstein-Yang-Mills equations for a null dust with Yang-Mills gauge charge are obtained by employing Wu-Yang \textit{ansatz}, namely, HD-EYM Vaidya solution. It is interesting to note that gravitational contribution of YM gauge charge for this ansatz is indeed opposite (attractive rather than repulsive) that of Maxwell charge. It turns out that the gravitational collapse of null dust with YM gauge charge admit strong curvature shell focusing naked singularities violating cosmic censorship. However, there is significant shrinkage of the initial data space for a naked singularity of the HD-Vaidya collapse due to presence of YM gauge charge. The effect of YM gauge charge on structure and location of the apparent and event horizons is also discussed. |
gr-qc/0606007 | Wieslaw Rudnicki | W. Rudnicki, R. J. Budzynski, W. Kondracki | Generalized strong curvature singularities and weak cosmic censorship in
cosmological space-times | Latex, 7 pages, no figures, to be published in Mod. Phys. Lett. A | Mod.Phys.Lett. A21 (2006) 1501-1510 | 10.1142/S0217732306020913 | null | gr-qc | null | This paper is a further development of the approach to weak cosmic censorship
proposed by the authors in Ref. 5. We state and prove a modified version of
that work's main result under significantly relaxed assumptions on the
asymptotic structure of space--time. The result, which imposes strong
constraints on the occurrence of naked singularities of the strong curvature
type, is in particular applicable to physically realistic cosmological models.
| [
{
"created": "Thu, 1 Jun 2006 19:13:05 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Rudnicki",
"W.",
""
],
[
"Budzynski",
"R. J.",
""
],
[
"Kondracki",
"W.",
""
]
] | This paper is a further development of the approach to weak cosmic censorship proposed by the authors in Ref. 5. We state and prove a modified version of that work's main result under significantly relaxed assumptions on the asymptotic structure of space--time. The result, which imposes strong constraints on the occurrence of naked singularities of the strong curvature type, is in particular applicable to physically realistic cosmological models. |
2011.02967 | Denitsa Staicova | Denitsa Staicova | Special cases of the Multi-Measure Model -- understanding the prolonged
inflation | 10 pages, 4 figures, final published version | JHEAp 36 (2022) 120-127 | 10.1016/j.jheap.2022.09.002 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The multi-measure model (MMM), in which one modifies the action to include
both the Riemannian measure and a non-Riemannian one, has proven to be able to
produce viable Universe evolution scenarios. In this article we consider two
special cases of the multi-measure model, in which we first decouple the two
kinetic terms in the Lagrangian entirely and later remove the dark charge of
the model. We show numerically that those special cases still possess the
needed evolutionary stages of the Universe and furthermore, for them one can
obtain a sufficient number of e-folds of the early inflation. In the first
case, the inflaton still moves backwards on the effective potential during
inflation, while in the second, it does not, meaning that this behavior comes
from the dark charge. We connect the model with hyperinflationary models and
investigate how the different epochs are born from the interplay between the
two scalar fields. We demonstrate that there is a dynamically induced slow-roll
epoch, which is prolonged by the complicated movement of the two scalars in the
field space. Finally, we show that while the adiabatic speed of sound can
become imaginary, the phase speed of sound remains real.
| [
{
"created": "Thu, 5 Nov 2020 16:46:28 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Aug 2021 12:04:50 GMT",
"version": "v2"
},
{
"created": "Fri, 30 Dec 2022 17:15:29 GMT",
"version": "v3"
}
] | 2023-01-02 | [
[
"Staicova",
"Denitsa",
""
]
] | The multi-measure model (MMM), in which one modifies the action to include both the Riemannian measure and a non-Riemannian one, has proven to be able to produce viable Universe evolution scenarios. In this article we consider two special cases of the multi-measure model, in which we first decouple the two kinetic terms in the Lagrangian entirely and later remove the dark charge of the model. We show numerically that those special cases still possess the needed evolutionary stages of the Universe and furthermore, for them one can obtain a sufficient number of e-folds of the early inflation. In the first case, the inflaton still moves backwards on the effective potential during inflation, while in the second, it does not, meaning that this behavior comes from the dark charge. We connect the model with hyperinflationary models and investigate how the different epochs are born from the interplay between the two scalar fields. We demonstrate that there is a dynamically induced slow-roll epoch, which is prolonged by the complicated movement of the two scalars in the field space. Finally, we show that while the adiabatic speed of sound can become imaginary, the phase speed of sound remains real. |
1711.09073 | Miriam Cabero | Miriam Cabero, Collin D. Capano, Ofek Fischer-Birnholtz, Badri
Krishnan, Alex B. Nielsen, Alexander H. Nitz and Christopher M. Biwer | Observational tests of the black hole area increase law | null | Phys. Rev. D 97, 124069 (2018) | 10.1103/PhysRevD.97.124069 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The black hole area theorem implies that when two black holes merge, the area
of the final black hole should be greater than the sum of the areas of the two
original black holes. We examine how this prediction can be tested with
gravitational-wave observations of binary black holes. By separately fitting
the early inspiral and final ringdown stages, we calculate the posterior
distributions for the masses and spins of the two initial and the final black
holes. This yields posterior distributions for the change in the area and thus
a statistical test of the validity of the area increase law. We illustrate this
method with a GW150914-like binary black hole waveform calculated using
numerical relativity, and detector sensitivities representative of both the
first observing run and the design configuration of Advanced LIGO. We obtain a
$\sim74.6\%$ probability that the simulated signal is consistent with the area
theorem with current sensitivity, improving to $\sim99.9\%$ when Advanced LIGO
reaches design sensitivity. An important ingredient in our test is a method of
estimating when the post-merger signal is well-fit by a damped sinusoid
ringdown waveform.
| [
{
"created": "Fri, 24 Nov 2017 18:40:32 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Jul 2018 11:44:07 GMT",
"version": "v2"
}
] | 2018-07-31 | [
[
"Cabero",
"Miriam",
""
],
[
"Capano",
"Collin D.",
""
],
[
"Fischer-Birnholtz",
"Ofek",
""
],
[
"Krishnan",
"Badri",
""
],
[
"Nielsen",
"Alex B.",
""
],
[
"Nitz",
"Alexander H.",
""
],
[
"Biwer",
"Christopher M... | The black hole area theorem implies that when two black holes merge, the area of the final black hole should be greater than the sum of the areas of the two original black holes. We examine how this prediction can be tested with gravitational-wave observations of binary black holes. By separately fitting the early inspiral and final ringdown stages, we calculate the posterior distributions for the masses and spins of the two initial and the final black holes. This yields posterior distributions for the change in the area and thus a statistical test of the validity of the area increase law. We illustrate this method with a GW150914-like binary black hole waveform calculated using numerical relativity, and detector sensitivities representative of both the first observing run and the design configuration of Advanced LIGO. We obtain a $\sim74.6\%$ probability that the simulated signal is consistent with the area theorem with current sensitivity, improving to $\sim99.9\%$ when Advanced LIGO reaches design sensitivity. An important ingredient in our test is a method of estimating when the post-merger signal is well-fit by a damped sinusoid ringdown waveform. |
1905.05654 | Salvatore Capozziello | Micol Benetti, Salvatore Capozziello, and Leila Lobato Graef | Swampland conjecture in $f(R)$ gravity by the Noether Symmetry Approach | 11 pages, 1 figure, accepted for publication in Physical Review D | Phys. Rev. D 100, 084013 (2019) | 10.1103/PhysRevD.100.084013 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Swampland conjecture has been recently proposed to connect early time
cosmological models with the string landscape, and then to understand if
related scalar fields and potentials can come from some fundamental theory in
the high energy regime. In this paper, we discuss swampland criteria for $f(R)$
gravity considering models where duality symmetry is present. In this
perspective, specific $f(R)$ models can naturally belong to the string
landscape. In particular, it is possible to show that duality is a Noether
symmetry emerging from dynamics. The selected $f(R)$ models, satisfying the
swampland conjecture, are consistent, in principle, with both early and
late-time cosmological behaviors.
| [
{
"created": "Tue, 14 May 2019 14:59:30 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Sep 2019 13:28:03 GMT",
"version": "v2"
}
] | 2020-11-09 | [
[
"Benetti",
"Micol",
""
],
[
"Capozziello",
"Salvatore",
""
],
[
"Graef",
"Leila Lobato",
""
]
] | Swampland conjecture has been recently proposed to connect early time cosmological models with the string landscape, and then to understand if related scalar fields and potentials can come from some fundamental theory in the high energy regime. In this paper, we discuss swampland criteria for $f(R)$ gravity considering models where duality symmetry is present. In this perspective, specific $f(R)$ models can naturally belong to the string landscape. In particular, it is possible to show that duality is a Noether symmetry emerging from dynamics. The selected $f(R)$ models, satisfying the swampland conjecture, are consistent, in principle, with both early and late-time cosmological behaviors. |
1104.3323 | Daniela Pugliese Dr | D. Pugliese and G. Montani | Stars in five dimensional Kaluza Klein gravity | 15 pages, 8 figures. To be published in EPJC | Eur.Phys.J.C71:1638,2011 | 10.1140/epjc/s10052-011-1638-x | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the five dimensional Kaluza Klein (KK) theory there is a well known class
of static and electromagnetic--free KK--equations characterized by a naked
singularity behavior, namely the Generalized Schwarzschild solution (GSS). We
present here a set of interior solutions of five dimensional KK--equations.
These equations have been numerically integrated to match the GSS in the
vacuum. The solutions are candidates to describe the possible interior perfect
fluid source of the exterior GSS metric and thus they can be models for stars
for static, neutral astrophysical objects in the ordinary (four dimensional)
spacetime.
| [
{
"created": "Sun, 17 Apr 2011 16:09:54 GMT",
"version": "v1"
}
] | 2011-05-18 | [
[
"Pugliese",
"D.",
""
],
[
"Montani",
"G.",
""
]
] | In the five dimensional Kaluza Klein (KK) theory there is a well known class of static and electromagnetic--free KK--equations characterized by a naked singularity behavior, namely the Generalized Schwarzschild solution (GSS). We present here a set of interior solutions of five dimensional KK--equations. These equations have been numerically integrated to match the GSS in the vacuum. The solutions are candidates to describe the possible interior perfect fluid source of the exterior GSS metric and thus they can be models for stars for static, neutral astrophysical objects in the ordinary (four dimensional) spacetime. |
1907.04960 | Jeffrey Hazboun | Xavier Siemens and Jeffrey S. Hazboun and Paul T. Baker and Sarah
Burke-Spolaor and Dustin Madison and Chiara Mingarelli and Joseph Simon and
Tristan Smith | Physics Beyond the Standard Model With Pulsar Timing Arrays | null | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Pulsar timing arrays (PTAs) will enable the detection of nanohertz
gravitational waves (GWs) from a population of supermassive binary black holes
(SMBBHs) in the next $\sim 3-7$ years. In addition, PTAs provide a rare
opportunity to probe exotic physics. Potential sources of GWs in the nanohertz
band include, cosmic strings and cosmic superstrings, inflation and, phase
transitions in the early universe. GW observations will also make possible
tests of gravitational theories that, by modifying Einstein's theory of general
relativity, attempt to explain the origin of cosmic acceleration and reconcile
quantum mechanics and gravity, two of the most profound challenges facing
fundamental physics today. Finally, PTAs also provide a new means to probe
certain dark matter models.
| [
{
"created": "Thu, 11 Jul 2019 00:27:22 GMT",
"version": "v1"
}
] | 2019-07-12 | [
[
"Siemens",
"Xavier",
""
],
[
"Hazboun",
"Jeffrey S.",
""
],
[
"Baker",
"Paul T.",
""
],
[
"Burke-Spolaor",
"Sarah",
""
],
[
"Madison",
"Dustin",
""
],
[
"Mingarelli",
"Chiara",
""
],
[
"Simon",
"Joseph",
""... | Pulsar timing arrays (PTAs) will enable the detection of nanohertz gravitational waves (GWs) from a population of supermassive binary black holes (SMBBHs) in the next $\sim 3-7$ years. In addition, PTAs provide a rare opportunity to probe exotic physics. Potential sources of GWs in the nanohertz band include, cosmic strings and cosmic superstrings, inflation and, phase transitions in the early universe. GW observations will also make possible tests of gravitational theories that, by modifying Einstein's theory of general relativity, attempt to explain the origin of cosmic acceleration and reconcile quantum mechanics and gravity, two of the most profound challenges facing fundamental physics today. Finally, PTAs also provide a new means to probe certain dark matter models. |
1502.01922 | Qiang Zhang | Qiang Zhang, Guang Yang, Qixiang Zou, Xinhe Meng, Keji Shen | Exploring the low redshift universe: two parametric models for effective
pressure | 11 pages, 24 figures | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Astrophysical observations have put unprecedentedly tight constraints on
cosmological theories. The $\Lambda$CDM model, mathematically simple and fits
observational data-sets well, is preferred for explaining the behavior of
universe. But many basic features of the dark sectors are still unknown, which
leaves rooms for various nonstandard cosmological hypotheses. As the pressure
of cosmological constant dark energy is unvarying, ignoring contributions from
radiation and curvature terms at low redshift, the effective pressure keeps
constant. In this paper, we propose two parametric models for non-constant
effective pressure in order to study the tiny deviation from $\Lambda$CDM at
low redshift. We recover our phenomenological models in the scenarios of
quintessence and phantom fields, and explore the behavior of scalar field and
potential. We constrain our model parameters with SNe Ia and BAO observations,
and detect subtle hints of $\omega_{de}<-1$ from the data fitting results of
both models, which indicates possibly a phantom dark energy scenario at
present.
| [
{
"created": "Thu, 5 Feb 2015 15:02:23 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Jun 2015 12:41:09 GMT",
"version": "v2"
}
] | 2015-06-19 | [
[
"Zhang",
"Qiang",
""
],
[
"Yang",
"Guang",
""
],
[
"Zou",
"Qixiang",
""
],
[
"Meng",
"Xinhe",
""
],
[
"Shen",
"Keji",
""
]
] | Astrophysical observations have put unprecedentedly tight constraints on cosmological theories. The $\Lambda$CDM model, mathematically simple and fits observational data-sets well, is preferred for explaining the behavior of universe. But many basic features of the dark sectors are still unknown, which leaves rooms for various nonstandard cosmological hypotheses. As the pressure of cosmological constant dark energy is unvarying, ignoring contributions from radiation and curvature terms at low redshift, the effective pressure keeps constant. In this paper, we propose two parametric models for non-constant effective pressure in order to study the tiny deviation from $\Lambda$CDM at low redshift. We recover our phenomenological models in the scenarios of quintessence and phantom fields, and explore the behavior of scalar field and potential. We constrain our model parameters with SNe Ia and BAO observations, and detect subtle hints of $\omega_{de}<-1$ from the data fitting results of both models, which indicates possibly a phantom dark energy scenario at present. |
1101.3264 | Muxin Han | Muxin Han, Carlo Rovelli | Spinfoam Fermions: PCT Symmetry, Dirac Determinant, and Correlation
Functions | 26 pages, 9 figures | Class. Quantum Grav. 30 (2013) 075007 | 10.1088/0264-9381/30/7/075007 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss fermion coupling in the framework of spinfoam quantum gravity. We
analyze the gravity-fermion spinfoam model and its fermion correlation
functions. We show that there is a spinfoam analog of PCT symmetry for the
fermion fields on spinfoam model, where a PCT theorem is proved for spinfoam
fermion correlation functions. We compute the determinant of the Dirac operator
for the fermions, where two presentations of the Dirac determinant are given in
terms of diagram expansions. We compute the fermion correlation functions and
show that they can be given by Feynman diagrams on the spinfoams, where the
Feynman propagators can be represented by a discretized path integral of a
world-line action along the edges of the underlying 2-complex.
| [
{
"created": "Mon, 17 Jan 2011 16:55:05 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Mar 2013 11:01:00 GMT",
"version": "v2"
}
] | 2015-03-17 | [
[
"Han",
"Muxin",
""
],
[
"Rovelli",
"Carlo",
""
]
] | We discuss fermion coupling in the framework of spinfoam quantum gravity. We analyze the gravity-fermion spinfoam model and its fermion correlation functions. We show that there is a spinfoam analog of PCT symmetry for the fermion fields on spinfoam model, where a PCT theorem is proved for spinfoam fermion correlation functions. We compute the determinant of the Dirac operator for the fermions, where two presentations of the Dirac determinant are given in terms of diagram expansions. We compute the fermion correlation functions and show that they can be given by Feynman diagrams on the spinfoams, where the Feynman propagators can be represented by a discretized path integral of a world-line action along the edges of the underlying 2-complex. |
2308.06727 | Abhishek Mathur | Abhishek Mathur | Quantum Fields from Causal Order | PhD thesis 2023, Raman Research Institute, submitted to Jawaharlal
Nehru University | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study different aspects of observer independent formulation of quantum
field theory (QFT) in curved spacetime background. This thesis is broadly
divided into two parts, in the first part we study an observer independent
scalar field vacuum, called as the Sorkin-Johnston (SJ) vacuum for a small mass
scalar field in a 2d causal diamond, and conformally coupled scalar field in
spacetimes which are conformally related to ultrastatic spacetime with time
dependent conformal factor. We study several properties of the SJ vacuum in
these spacetimes and compare with the known vacua. In the second part of the
thesis we study a spacetime formulation of entanglement entropy, called as the
Sorkin Spacetime Entanglement Entropy (SSEE), in curved spacetime, which makes
use of the Wightman function restricted to the region of interest and the
spacetime field commutator. We study SSEE in cylinder slab spacetimes and
compare the result with the Calabrese-Cardy entanglement entropy. We also study
SSEE of de Sitter and black hole horizons and compared with known results.
| [
{
"created": "Sun, 13 Aug 2023 09:07:05 GMT",
"version": "v1"
}
] | 2023-08-15 | [
[
"Mathur",
"Abhishek",
""
]
] | We study different aspects of observer independent formulation of quantum field theory (QFT) in curved spacetime background. This thesis is broadly divided into two parts, in the first part we study an observer independent scalar field vacuum, called as the Sorkin-Johnston (SJ) vacuum for a small mass scalar field in a 2d causal diamond, and conformally coupled scalar field in spacetimes which are conformally related to ultrastatic spacetime with time dependent conformal factor. We study several properties of the SJ vacuum in these spacetimes and compare with the known vacua. In the second part of the thesis we study a spacetime formulation of entanglement entropy, called as the Sorkin Spacetime Entanglement Entropy (SSEE), in curved spacetime, which makes use of the Wightman function restricted to the region of interest and the spacetime field commutator. We study SSEE in cylinder slab spacetimes and compare the result with the Calabrese-Cardy entanglement entropy. We also study SSEE of de Sitter and black hole horizons and compared with known results. |
2407.04853 | Carsten Gundlach | Carsten Gundlach | The two-body problem in 2+1 spacetime dimensions with negative
cosmological constant: two point particles | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We work towards the general solution of the two-body problem in
2+1-dimensional general relativity with a negative cosmological constant. The
BTZ solutions corresponding to black holes, point particles and overspinning
particles can be considered either as objects in their own right, or as the
exterior solution of compact objects with a given mass $M$ and spin $J$, such
as rotating fluid stars. We compare and contrast the metric approach to the
group-theoretical one of characterising the BTZ solutions as identifications of
2+1-dimensional anti-de Sitter spacetime under an isometry. We then move on to
the two-body problem. In this paper, we restrict the two objects to the point
particle range $|J|-1\le M<-|J|$, or their massless equivalents, obtained by an
infinite boost. (Both anti-de Sitter space and massless particles have $M=-1$,
$J=0$). We derive analytic expressions for the total mass $M_\text{tot}$ and
spin $J_\text{tot}$ of the system in terms of the six gauge-invariant
parameters of the two-particle system: the rest mass and spin of each object,
and the impact parameter and energy of the orbit. Based on work of Holst and
Matschull on the case of two massless, nonspinning particles, we conjecture
that the black hole formation threshold is $M_\text{tot}=|J_\text{tot}|$. The
threshold solutions are then extremal black holes. We determine when the global
geometry is a black hole, an eternal binary system, or a closed universe.
| [
{
"created": "Fri, 5 Jul 2024 20:21:20 GMT",
"version": "v1"
}
] | 2024-07-09 | [
[
"Gundlach",
"Carsten",
""
]
] | We work towards the general solution of the two-body problem in 2+1-dimensional general relativity with a negative cosmological constant. The BTZ solutions corresponding to black holes, point particles and overspinning particles can be considered either as objects in their own right, or as the exterior solution of compact objects with a given mass $M$ and spin $J$, such as rotating fluid stars. We compare and contrast the metric approach to the group-theoretical one of characterising the BTZ solutions as identifications of 2+1-dimensional anti-de Sitter spacetime under an isometry. We then move on to the two-body problem. In this paper, we restrict the two objects to the point particle range $|J|-1\le M<-|J|$, or their massless equivalents, obtained by an infinite boost. (Both anti-de Sitter space and massless particles have $M=-1$, $J=0$). We derive analytic expressions for the total mass $M_\text{tot}$ and spin $J_\text{tot}$ of the system in terms of the six gauge-invariant parameters of the two-particle system: the rest mass and spin of each object, and the impact parameter and energy of the orbit. Based on work of Holst and Matschull on the case of two massless, nonspinning particles, we conjecture that the black hole formation threshold is $M_\text{tot}=|J_\text{tot}|$. The threshold solutions are then extremal black holes. We determine when the global geometry is a black hole, an eternal binary system, or a closed universe. |
1304.2203 | Alejandro Cabo | Alejandro Cabo Montes de Oca and Jorge Casti\~neiras | On radiation reaction and the Abraham-Lorentz-Dirac equation | 6 pages, 1 figure | null | null | null | gr-qc physics.acc-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is underlined that the Lienard-Wiechert solutions indicate that after the
external force is instantly removed from a small charged particle, the field in
its close neighborhood becomes a Lorentz boosted Coulomb field. It suggests
that the force of the self-field on the particle should instantaneously vanish
after a sudden removal of the external force. A minimal modification of
Abraham-Lorentz-Dirac equation is searched seeking to implement this property.
A term assuring this behavior is added to the equation by maintaining Lorentz
covariance and vanishing scalar product with the four-velocity. The simple
Dirac constant force example does not show runaway acceleration.
| [
{
"created": "Mon, 8 Apr 2013 13:36:10 GMT",
"version": "v1"
}
] | 2013-09-13 | [
[
"de Oca",
"Alejandro Cabo Montes",
""
],
[
"Castiñeiras",
"Jorge",
""
]
] | It is underlined that the Lienard-Wiechert solutions indicate that after the external force is instantly removed from a small charged particle, the field in its close neighborhood becomes a Lorentz boosted Coulomb field. It suggests that the force of the self-field on the particle should instantaneously vanish after a sudden removal of the external force. A minimal modification of Abraham-Lorentz-Dirac equation is searched seeking to implement this property. A term assuring this behavior is added to the equation by maintaining Lorentz covariance and vanishing scalar product with the four-velocity. The simple Dirac constant force example does not show runaway acceleration. |
1701.03718 | Paul Klinger | Piotr T. Chru\'sciel, Erwann Delay (LMA), Paul Klinger | Non-singular spacetimes with a negative cosmological constant: III.
Stationary solutions with matter fields | 27 pages, v2: journal accepted version | Phys. Rev. D 95, 104039 (2017) | 10.1103/PhysRevD.95.104039 | UWThPh-2016-30 | gr-qc hep-th math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Generalising the results in arXiv:1612.00281, we construct
infinite-dimensional families of non-singular stationary space times, solutions
of Yang-Mills-Higgs-Einstein-Maxwell-Chern-Simons-dilaton-scalar field
equations with a negative cosmological constant. The families include an
infinite-dimensional family of solutions with the usual AdS conformal structure
at conformal infinity.
| [
{
"created": "Fri, 13 Jan 2017 16:45:10 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Apr 2017 16:02:08 GMT",
"version": "v2"
}
] | 2017-06-07 | [
[
"Chruściel",
"Piotr T.",
"",
"LMA"
],
[
"Delay",
"Erwann",
"",
"LMA"
],
[
"Klinger",
"Paul",
""
]
] | Generalising the results in arXiv:1612.00281, we construct infinite-dimensional families of non-singular stationary space times, solutions of Yang-Mills-Higgs-Einstein-Maxwell-Chern-Simons-dilaton-scalar field equations with a negative cosmological constant. The families include an infinite-dimensional family of solutions with the usual AdS conformal structure at conformal infinity. |
1912.07094 | Matthew J. Lake Dr | Matthew J. Lake, Marek Miller and Shi-Dong Liang | Generalised uncertainty relations for angular momentum and spin in
quantum geometry | 28 pages of main text, plus 12 additional pages split between 4
appendices and 3 pages of references. No figures. Invited contribution to the
Universe special issue "Rotation Effects in Relativity", Matteo Ruggiero ed.
Published version | Universe 6 (2020) 4, 56 | 10.3390/universe6040056 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive generalised uncertainty relations (GURs) for angular momentum and
spin in the smeared-space model of quantum geometry. The model implements a
minimum length and a minimum linear momentum, and recovers both the generalised
uncertainty principle (GUP) and the extended uncertainty principle (EUP) within
a single formalism. In this paper, we investigate the consequences of these
results for particles with extrinsic and intrinsic angular momentum, and obtain
generalisations of the canonical ${\rm so(3)}$ and ${\rm su(2)}$ algebras. We
find that, although ${\rm SO(3)}$ symmetry is preserved on three-dimensional
slices of an enlarged phase space, individual subcomponents of the generalised
generators obey nontrivial subalgebras. These give rise to GURs for angular
momentum while leaving the canonical commutation relations intact except for a
simple rescaling, $\hbar \rightarrow \hbar + \beta$. The value of the new
parameter, $\beta \simeq \hbar \times 10^{-61}$, is determined by the ratio of
the dark energy density to the Planck density. Here, we assume the former to be
of the order of the Planck length and the latter to be of the order of the de
Sitter momentum $\sim \hbar\sqrt{\Lambda}$, where $\Lambda$ is the cosmological
constant. In the smeared-space model, $\hbar$ and $\beta$ are interpreted as
the quantisation scales for matter and geometry, respectively, and a quantum
state vector is associated with the spatial background. We show that this also
gives rise to a rescaled Lie algebra for generalised spin operators, together
with associated subalgebras that are analogous to those for orbital angular
momentum. Remarkably, consistency of the algebraic structure requires the
quantum state associated with a flat background to be fermionic, with spin
eigenvalues $\pm \beta/2$. Finally, the modified spin algebra leads to GURs for
spin measurements.
| [
{
"created": "Sun, 15 Dec 2019 19:33:21 GMT",
"version": "v1"
},
{
"created": "Sun, 29 Mar 2020 18:27:42 GMT",
"version": "v2"
},
{
"created": "Tue, 26 May 2020 13:35:45 GMT",
"version": "v3"
}
] | 2020-05-27 | [
[
"Lake",
"Matthew J.",
""
],
[
"Miller",
"Marek",
""
],
[
"Liang",
"Shi-Dong",
""
]
] | We derive generalised uncertainty relations (GURs) for angular momentum and spin in the smeared-space model of quantum geometry. The model implements a minimum length and a minimum linear momentum, and recovers both the generalised uncertainty principle (GUP) and the extended uncertainty principle (EUP) within a single formalism. In this paper, we investigate the consequences of these results for particles with extrinsic and intrinsic angular momentum, and obtain generalisations of the canonical ${\rm so(3)}$ and ${\rm su(2)}$ algebras. We find that, although ${\rm SO(3)}$ symmetry is preserved on three-dimensional slices of an enlarged phase space, individual subcomponents of the generalised generators obey nontrivial subalgebras. These give rise to GURs for angular momentum while leaving the canonical commutation relations intact except for a simple rescaling, $\hbar \rightarrow \hbar + \beta$. The value of the new parameter, $\beta \simeq \hbar \times 10^{-61}$, is determined by the ratio of the dark energy density to the Planck density. Here, we assume the former to be of the order of the Planck length and the latter to be of the order of the de Sitter momentum $\sim \hbar\sqrt{\Lambda}$, where $\Lambda$ is the cosmological constant. In the smeared-space model, $\hbar$ and $\beta$ are interpreted as the quantisation scales for matter and geometry, respectively, and a quantum state vector is associated with the spatial background. We show that this also gives rise to a rescaled Lie algebra for generalised spin operators, together with associated subalgebras that are analogous to those for orbital angular momentum. Remarkably, consistency of the algebraic structure requires the quantum state associated with a flat background to be fermionic, with spin eigenvalues $\pm \beta/2$. Finally, the modified spin algebra leads to GURs for spin measurements. |
2010.05278 | Muhsin Aljaf | Muhsin Aljaf, Daniele Gregoris, Martiros Khurshudyan | Assessing the foundation and applicability of some dark energy fluid
models in the Dirac-Born-Infeld framework | Matches the published version; 24 pages and 8 figures | International Journal of Modern Physics A (2022) | 10.1142/S0217751X22502116 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we will deepen the understanding of some fluid models proposed
by other authors for the description of dark energy. Specifically, we will show
that the so-called (Modified) Berthelot fluid is the hydrodynamic realization
of the free Dirac-Born-Infeld theory and that the Dieterici fluid admits a
non-relativistic $k$-essence formulation; for the former model the evolution of
the scalar field will be written in terms of some cosmographic parameters. The
latter model will also be tested using Machine Learning algorithms with respect
to cosmic chronometers data, and results about the dynamics at a background
level will be compared with those arising when other fluids (Generalized
Chaplygin Gas and Anton-Schmidt) are considered. Due to some cosmic opacity
effects, the background cosmology of universes filled by these inequivalent
fluids, as they arise in physically different theories, may not be enough for
discriminating among them. Thus, a perturbation analysis in the long-wavelength
limit is carried out revealing a rich variety of possible behaviors. It will
also be shown that the free Dirac-Born-Infeld theory cannot account for flat
galactic rotation curves, and therefore we derive an appropriate relationship
between the scalar field potential and the brane tension for achieving this
goal; this provides an estimate for the dark matter adiabatic speed of sound
inside the halo consistent with other literature. A certain relationship
between the Newtonian gravitational potential within the galaxy and the
Lagrangian potential in the non-relativistic regime for the (Modified)
Berthelot fluid will also be enlightened.
| [
{
"created": "Sun, 11 Oct 2020 16:22:44 GMT",
"version": "v1"
},
{
"created": "Sun, 12 Dec 2021 14:21:38 GMT",
"version": "v2"
},
{
"created": "Sat, 28 Jan 2023 04:26:43 GMT",
"version": "v3"
}
] | 2023-01-31 | [
[
"Aljaf",
"Muhsin",
""
],
[
"Gregoris",
"Daniele",
""
],
[
"Khurshudyan",
"Martiros",
""
]
] | In this paper, we will deepen the understanding of some fluid models proposed by other authors for the description of dark energy. Specifically, we will show that the so-called (Modified) Berthelot fluid is the hydrodynamic realization of the free Dirac-Born-Infeld theory and that the Dieterici fluid admits a non-relativistic $k$-essence formulation; for the former model the evolution of the scalar field will be written in terms of some cosmographic parameters. The latter model will also be tested using Machine Learning algorithms with respect to cosmic chronometers data, and results about the dynamics at a background level will be compared with those arising when other fluids (Generalized Chaplygin Gas and Anton-Schmidt) are considered. Due to some cosmic opacity effects, the background cosmology of universes filled by these inequivalent fluids, as they arise in physically different theories, may not be enough for discriminating among them. Thus, a perturbation analysis in the long-wavelength limit is carried out revealing a rich variety of possible behaviors. It will also be shown that the free Dirac-Born-Infeld theory cannot account for flat galactic rotation curves, and therefore we derive an appropriate relationship between the scalar field potential and the brane tension for achieving this goal; this provides an estimate for the dark matter adiabatic speed of sound inside the halo consistent with other literature. A certain relationship between the Newtonian gravitational potential within the galaxy and the Lagrangian potential in the non-relativistic regime for the (Modified) Berthelot fluid will also be enlightened. |
gr-qc/0101059 | Roy Maartens | Roy Maartens (Portsmouth) | Geometry and dynamics of the brane-world | Minor corrections to Eqs. 14, 42, 64, and reference updates | null | 10.1142/9789812810021_0008 | null | gr-qc astro-ph hep-th | null | Recent developments in string theory have led to 5-dimensional warped
spacetime models in which standard-model fields are confined to a 3-brane (the
observed universe), while gravity can propagate in the fifth dimension. Gravity
is localized near the brane at low energies, even if the extra dimension is
noncompact. A review is given of the classical geometry and dynamics of these
brane-world models. The field equations on the brane modify the general
relativity equations in two ways: local 5-D effects are imprinted on the brane
as a result of its embedding, and are significant at high energies; nonlocal
effects arise from the 5-D Weyl tensor. The Weyl tensor transmits tidal
(Coulomb), gravitomagnetic and gravitational wave effects to the brane from the
5-D nonlocal gravitational field. Local high-energy effects modify the dynamics
of inflation, and increase the amplitude of scalar and tensor perturbations
generated by inflation. Nonlocal effects introduce new features in cosmological
perturbations. They induce a non-adiabatic mode in scalar perturbations and
massive modes in vector and tensor perturbations, and they can support vector
perturbations even in the absence of matter vorticity. In astrophysics, local
and nonlocal effects introduce fundamental changes to gravitational collapse
and black hole solutions.
| [
{
"created": "Tue, 16 Jan 2001 14:38:39 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Apr 2001 12:59:16 GMT",
"version": "v2"
}
] | 2017-08-23 | [
[
"Maartens",
"Roy",
"",
"Portsmouth"
]
] | Recent developments in string theory have led to 5-dimensional warped spacetime models in which standard-model fields are confined to a 3-brane (the observed universe), while gravity can propagate in the fifth dimension. Gravity is localized near the brane at low energies, even if the extra dimension is noncompact. A review is given of the classical geometry and dynamics of these brane-world models. The field equations on the brane modify the general relativity equations in two ways: local 5-D effects are imprinted on the brane as a result of its embedding, and are significant at high energies; nonlocal effects arise from the 5-D Weyl tensor. The Weyl tensor transmits tidal (Coulomb), gravitomagnetic and gravitational wave effects to the brane from the 5-D nonlocal gravitational field. Local high-energy effects modify the dynamics of inflation, and increase the amplitude of scalar and tensor perturbations generated by inflation. Nonlocal effects introduce new features in cosmological perturbations. They induce a non-adiabatic mode in scalar perturbations and massive modes in vector and tensor perturbations, and they can support vector perturbations even in the absence of matter vorticity. In astrophysics, local and nonlocal effects introduce fundamental changes to gravitational collapse and black hole solutions. |
1303.0850 | Norman Metzner | Norman Metzner | Twistor Theory of Higher-Dimensional Black Holes - Part I: Theory | 26 pages, 7 figures | Class. Quantum Grav. 30 (2013) 095001 | 10.1088/0264-9381/30/9/095001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The correspondence between stationary, axisymmetric, asymptotically flat
space-times and bundles over a reduced twistor space has been established in
four dimensions. The main impediment for an application of this correspondence
to examples in higher dimensions has been the lack of a higher-dimensional
equivalent of the Ernst potential. This article will propose such a generalized
Ernst potential, point out where the rod structure of the space-time can be
found in the twistor picture and thereby provide a procedure for generating
solutions to the Einstein equations in higher dimensions from the rod structure
and other asymptotic data. An important result for the study of
five-dimensional examples will be the theorem which relates the patching
matrices on the outer semi-infinite rods.
| [
{
"created": "Mon, 4 Mar 2013 21:03:47 GMT",
"version": "v1"
}
] | 2015-06-15 | [
[
"Metzner",
"Norman",
""
]
] | The correspondence between stationary, axisymmetric, asymptotically flat space-times and bundles over a reduced twistor space has been established in four dimensions. The main impediment for an application of this correspondence to examples in higher dimensions has been the lack of a higher-dimensional equivalent of the Ernst potential. This article will propose such a generalized Ernst potential, point out where the rod structure of the space-time can be found in the twistor picture and thereby provide a procedure for generating solutions to the Einstein equations in higher dimensions from the rod structure and other asymptotic data. An important result for the study of five-dimensional examples will be the theorem which relates the patching matrices on the outer semi-infinite rods. |
gr-qc/9608042 | Karen Brewster | Abhay Ashtekar, Jiri Bicak, Bernd G. Schmidt | Asymptotic Structure of Symmetry Reduced General Relativity | 39 Pages, REVTEX, CGPG-96/5-1 | Phys.Rev.D55:669-686,1997 | 10.1103/PhysRevD.55.669 | null | gr-qc | null | Gravitational waves with a space-translation Killing field are considered. In
this case, the 4-dimensional Einstein vacuum equations are equivalent to the
3-dimensional Einstein equations with certain matter sources. This interplay
between 4- and 3- dimensional general relativity can be exploited effectively
to analyze issues pertaining to 4 dimensions in terms of the 3-dimensional
structures. An example is provided by the asymptotic structure at null
infinity: While these space-times fail to be asymptotically flat in 4
dimensions, they can admit a regular completion at null infinity in 3
dimensions. This completion is used to analyze the asymptotic symmetries,
introduce the analog of the 4-dimensional Bondi energy-momentum and write down
a flux formula.
The analysis is also of interest from a purely 3-dimensional perspective
because it pertains to a diffeomorphism invariant 3-dimensional field theory
with {\it local} degrees of freedom, i.e., to a midi-superspace. Furthermore,
due to certain peculiarities of 3 dimensions, the description of null infinity
does have a number of features that are quite surprising because they do not
arise in the Bondi-Penrose description in 4 dimensions.
| [
{
"created": "Fri, 16 Aug 1996 18:00:09 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Ashtekar",
"Abhay",
""
],
[
"Bicak",
"Jiri",
""
],
[
"Schmidt",
"Bernd G.",
""
]
] | Gravitational waves with a space-translation Killing field are considered. In this case, the 4-dimensional Einstein vacuum equations are equivalent to the 3-dimensional Einstein equations with certain matter sources. This interplay between 4- and 3- dimensional general relativity can be exploited effectively to analyze issues pertaining to 4 dimensions in terms of the 3-dimensional structures. An example is provided by the asymptotic structure at null infinity: While these space-times fail to be asymptotically flat in 4 dimensions, they can admit a regular completion at null infinity in 3 dimensions. This completion is used to analyze the asymptotic symmetries, introduce the analog of the 4-dimensional Bondi energy-momentum and write down a flux formula. The analysis is also of interest from a purely 3-dimensional perspective because it pertains to a diffeomorphism invariant 3-dimensional field theory with {\it local} degrees of freedom, i.e., to a midi-superspace. Furthermore, due to certain peculiarities of 3 dimensions, the description of null infinity does have a number of features that are quite surprising because they do not arise in the Bondi-Penrose description in 4 dimensions. |
0709.3559 | Maria Babiuc | M. C. Babiuc, S. Husa, D. Alic, I. Hinder, C. Lechner, E. Schnetter,
B. Szilagyi, Y. Zlochower, N. Dorband, D. Pollney, J. Winicour | Implementation of standard testbeds for numerical relativity | Corrected version | Class.Quant.Grav.25:125012,2008 | 10.1088/0264-9381/25/12/125012 | null | gr-qc | null | We discuss results that have been obtained from the implementation of the
initial round of testbeds for numerical relativity which was proposed in the
first paper of the Apples with Apples Alliance. We present benchmark results
for various codes which provide templates for analyzing the testbeds and to
draw conclusions about various features of the codes. This allows us to sharpen
the initial test specifications, design a new test and add theoretical insight.
| [
{
"created": "Sat, 22 Sep 2007 03:41:21 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Apr 2008 20:44:34 GMT",
"version": "v2"
},
{
"created": "Wed, 14 May 2008 20:01:44 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Babiuc",
"M. C.",
""
],
[
"Husa",
"S.",
""
],
[
"Alic",
"D.",
""
],
[
"Hinder",
"I.",
""
],
[
"Lechner",
"C.",
""
],
[
"Schnetter",
"E.",
""
],
[
"Szilagyi",
"B.",
""
],
[
"Zlochower",
"Y.",
... | We discuss results that have been obtained from the implementation of the initial round of testbeds for numerical relativity which was proposed in the first paper of the Apples with Apples Alliance. We present benchmark results for various codes which provide templates for analyzing the testbeds and to draw conclusions about various features of the codes. This allows us to sharpen the initial test specifications, design a new test and add theoretical insight. |
1910.07841 | Paolo Pani | Sayak Datta, Richard Brito, Sukanta Bose, Paolo Pani, Scott A. Hughes | Tidal heating as a discriminator for horizons in extreme mass ratio
inspirals | v2: 8+4 pages, 5 figures, one new plot. Version to appear in PRD | Phys. Rev. D 101, 044004 (2020) | 10.1103/PhysRevD.101.044004 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The defining feature of a classical black hole is being a perfect absorber.
Any evidence showing otherwise would indicate a departure from the standard
black-hole picture. Energy and angular momentum absorption by the horizon of a
black hole is responsible for tidal heating in a binary. This effect is
particularly important in the latest stages of an extreme mass ratio inspiral
around a spinning supermassive object, one of the main targets of the future
LISA mission. We study how this effect can be used to probe the nature of
supermassive objects in a model independent way. We compute the orbital
dephasing and the gravitational-wave signal emitted by a point particle in
circular, equatorial motion around a spinning supermassive object to the
leading order in the mass ratio. Absence of absorption by the central object
can affect the gravitational-wave signal dramatically, especially at high spin.
This effect will make it possible to put an unparalleled upper bound on the
reflectivity of exotic compact objects, at the level of ${\cal O}(0.01)\%$.
This stringent bound would exclude the possibility of observing echoes in the
ringdown of a supermassive binary merger.
| [
{
"created": "Thu, 17 Oct 2019 11:51:30 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Jan 2020 15:48:51 GMT",
"version": "v2"
}
] | 2020-02-12 | [
[
"Datta",
"Sayak",
""
],
[
"Brito",
"Richard",
""
],
[
"Bose",
"Sukanta",
""
],
[
"Pani",
"Paolo",
""
],
[
"Hughes",
"Scott A.",
""
]
] | The defining feature of a classical black hole is being a perfect absorber. Any evidence showing otherwise would indicate a departure from the standard black-hole picture. Energy and angular momentum absorption by the horizon of a black hole is responsible for tidal heating in a binary. This effect is particularly important in the latest stages of an extreme mass ratio inspiral around a spinning supermassive object, one of the main targets of the future LISA mission. We study how this effect can be used to probe the nature of supermassive objects in a model independent way. We compute the orbital dephasing and the gravitational-wave signal emitted by a point particle in circular, equatorial motion around a spinning supermassive object to the leading order in the mass ratio. Absence of absorption by the central object can affect the gravitational-wave signal dramatically, especially at high spin. This effect will make it possible to put an unparalleled upper bound on the reflectivity of exotic compact objects, at the level of ${\cal O}(0.01)\%$. This stringent bound would exclude the possibility of observing echoes in the ringdown of a supermassive binary merger. |
gr-qc/0306008 | Martin Bojowald | Martin Bojowald and Hugo A. Morales-Tecotl | Cosmological applications of loop quantum gravity | 42 pages, 4 figures, written for the proceedings of the Fifth Mexican
School (DGFM): The Early Universe and Observational Cosmology | Lect.Notes Phys.646:421-462,2004 | 10.1007/b97189 | CGPG-03/6-1 | gr-qc astro-ph hep-th | null | After a brief introduction to classical and quantum gravity we discuss
applications of loop quantum gravity in the cosmological realm. This includes
the basic formalism and recent results of loop quantum cosmology, and a
computation of modified dispersion relations for quantum gravity phenomenology.
The presentation is held at a level which does not require much background
knowledge in general relativity or mathematical techniques such as functional
analysis, so as to make the article accessible to graduate students and
researchers from other fields.
| [
{
"created": "Mon, 2 Jun 2003 20:01:43 GMT",
"version": "v1"
}
] | 2017-08-23 | [
[
"Bojowald",
"Martin",
""
],
[
"Morales-Tecotl",
"Hugo A.",
""
]
] | After a brief introduction to classical and quantum gravity we discuss applications of loop quantum gravity in the cosmological realm. This includes the basic formalism and recent results of loop quantum cosmology, and a computation of modified dispersion relations for quantum gravity phenomenology. The presentation is held at a level which does not require much background knowledge in general relativity or mathematical techniques such as functional analysis, so as to make the article accessible to graduate students and researchers from other fields. |
2207.14305 | Marco Astorino | Marco Astorino | Removal of conical singularities from rotating C-metrics and dual CFT
entropy | 18 pages, no figures | JHEP 10 (2022) 074 | 10.1007/JHEP10(2022)074 | LIFT-2-2.22 | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We show how to remove from the rotating C-metric spacetime, which describes
accelerating Kerr black holes, both conical singularities. This can be done by
embedding the metric into a swirling gravitational universe, through a proper
Ehlers transformation. The spin-spin interaction between the external
rotational background and the black hole provides the source of the
acceleration without the need of rods or strings. The physical properties and
entropy of the new solution are studied using near horizon and dual conformal
techniques of the Kerr/CFT correspondence. The charged case is also analysed:
Accelerating Reissner-Nordstrom and Accelerating Kerr-Newman space-times
embedded in a swirling universe are also generated.
| [
{
"created": "Thu, 28 Jul 2022 18:00:00 GMT",
"version": "v1"
},
{
"created": "Sun, 20 Aug 2023 10:51:37 GMT",
"version": "v2"
}
] | 2023-08-22 | [
[
"Astorino",
"Marco",
""
]
] | We show how to remove from the rotating C-metric spacetime, which describes accelerating Kerr black holes, both conical singularities. This can be done by embedding the metric into a swirling gravitational universe, through a proper Ehlers transformation. The spin-spin interaction between the external rotational background and the black hole provides the source of the acceleration without the need of rods or strings. The physical properties and entropy of the new solution are studied using near horizon and dual conformal techniques of the Kerr/CFT correspondence. The charged case is also analysed: Accelerating Reissner-Nordstrom and Accelerating Kerr-Newman space-times embedded in a swirling universe are also generated. |
gr-qc/9603057 | Valter Moretti | V. Moretti (Dept. Phys. Univ. Trento (Italy) and INFN) | Canonical Quantization of Photons in a Rindler Wedge | 32 pages, latex, no figures, revised version, no changes in the
physical results, to be published in J. Math. Phys | J.Math.Phys.38:2922-2953,1997 | 10.1063/1.532026 | UTF 376 | gr-qc hep-th | null | Photons and thermal photons are studied in the Rindler Wedge employing
Feynman's gauge and canonical quantization. A Gupta-Bleuler-like formalism is
explicitly implemented. Non thermal Wightman functions and related (Euclidean
and Lorentzian) Green functions are explicitly calculated and their complex
time analytic structure is analyzed using the Fulling-Ruijsenaars master
function. The invariance of the advanced minus retarded fundamental solution is
checked and a Ward identity discussed. It is suggested the KMS condition can be
implemented to define thermal states also dealing with unphysical photons.
Following this way, thermal Wightman functions and related (Euclidean and
Lorentzian) Green functions are built up. Their analytic structure is examined
employing a thermal master function as in the non thermal case and other
corresponding properties are discussed. Some subtleties arising dealing with
unphysical photons in presence of the Rindler conical singularity are pointed
out. In particular, a family of thermal Wightman and Schwinger functions with
the same physical content is proved to exist due to a remaining static gauge
ambiguity. A photon version of Bisognano-Wichmann theorem is investigated in
the case of photons propagating in the Rindler Wedge employing Wightman
functions. Despite of the found ambiguity in defining Rindler Green functions,
the coincidence of $(\beta = 2\pi)$-Rindler Wightman functions and Minkowski
Wightman functions is proved dealing with test functions related to physical
photons and Lorentz photons.
| [
{
"created": "Thu, 28 Mar 1996 16:03:38 GMT",
"version": "v1"
},
{
"created": "Fri, 29 Mar 1996 15:38:37 GMT",
"version": "v2"
},
{
"created": "Thu, 25 Apr 1996 10:48:45 GMT",
"version": "v3"
},
{
"created": "Fri, 13 Dec 1996 18:57:37 GMT",
"version": "v4"
}
] | 2008-11-26 | [
[
"Moretti",
"V.",
"",
"Dept. Phys. Univ. Trento"
]
] | Photons and thermal photons are studied in the Rindler Wedge employing Feynman's gauge and canonical quantization. A Gupta-Bleuler-like formalism is explicitly implemented. Non thermal Wightman functions and related (Euclidean and Lorentzian) Green functions are explicitly calculated and their complex time analytic structure is analyzed using the Fulling-Ruijsenaars master function. The invariance of the advanced minus retarded fundamental solution is checked and a Ward identity discussed. It is suggested the KMS condition can be implemented to define thermal states also dealing with unphysical photons. Following this way, thermal Wightman functions and related (Euclidean and Lorentzian) Green functions are built up. Their analytic structure is examined employing a thermal master function as in the non thermal case and other corresponding properties are discussed. Some subtleties arising dealing with unphysical photons in presence of the Rindler conical singularity are pointed out. In particular, a family of thermal Wightman and Schwinger functions with the same physical content is proved to exist due to a remaining static gauge ambiguity. A photon version of Bisognano-Wichmann theorem is investigated in the case of photons propagating in the Rindler Wedge employing Wightman functions. Despite of the found ambiguity in defining Rindler Green functions, the coincidence of $(\beta = 2\pi)$-Rindler Wightman functions and Minkowski Wightman functions is proved dealing with test functions related to physical photons and Lorentz photons. |
gr-qc/9611009 | Carlos O. Lousto | Carlos O. Lousto (Univ. Utah) and Francisco D. Mazzitelli (Univ.
Buenos Aires) | An exact self-consistent gravitational shock wave in semiclassical
gravity | 13 pages, REVTEX, 4 PS figures. Revised version contains a derivation
of the solution compatible with its distributional character. The final
results, though, are the same | Phys.Rev.D56:3471-3477,1997 | 10.1103/PhysRevD.56.3471 | null | gr-qc hep-th | null | We find a self-consistent pp-gravitational shock wave solution to the
semiclassical Einstein equations resulting from the $1/N$ approach to the
effective action. We model the renormalized matter stress-energy-momentum
tensor by $N$ massless scalar fields in the Minkowski vacuum plus a classical
particle. We show that quantum effects generate a milder singularity at the
position of the particle than the classical solution, but the singularity does
not disappear. At large distances from the particle, the quantum correction
decreases slowly, as $1/\rho^2$ ($\rho$ being the distance to the particle in
the shock wave plane). We argue that this large distance correction is a
necessary consequence of quantum gravity.
| [
{
"created": "Tue, 5 Nov 1996 01:35:42 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Jul 1997 22:55:03 GMT",
"version": "v2"
}
] | 2011-09-09 | [
[
"Lousto",
"Carlos O.",
"",
"Univ. Utah"
],
[
"Mazzitelli",
"Francisco D.",
"",
"Univ.\n Buenos Aires"
]
] | We find a self-consistent pp-gravitational shock wave solution to the semiclassical Einstein equations resulting from the $1/N$ approach to the effective action. We model the renormalized matter stress-energy-momentum tensor by $N$ massless scalar fields in the Minkowski vacuum plus a classical particle. We show that quantum effects generate a milder singularity at the position of the particle than the classical solution, but the singularity does not disappear. At large distances from the particle, the quantum correction decreases slowly, as $1/\rho^2$ ($\rho$ being the distance to the particle in the shock wave plane). We argue that this large distance correction is a necessary consequence of quantum gravity. |
gr-qc/0702093 | Bianca Dittrich | Bianca Dittrich, Johannes Tambornino | Gauge invariant perturbations around symmetry reduced sectors of general
relativity: applications to cosmology | 39 pages, 1 figure | Class.Quant.Grav.24:4543-4586,2007 | 10.1088/0264-9381/24/18/001 | null | gr-qc astro-ph hep-th | null | We develop a gauge invariant canonical perturbation scheme for perturbations
around symmetry reduced sectors in generally covariant theories, such as
general relativity. The central objects of investigation are gauge invariant
observables which encode the dynamics of the system. We apply this scheme to
perturbations around a homogeneous and isotropic sector (cosmology) of general
relativity. The background variables of this homogeneous and isotropic sector
are treated fully dynamically which allows us to approximate the observables to
arbitrary high order in a self--consistent and fully gauge invariant manner.
Methods to compute these observables are given. The question of backreaction
effects of inhomogeneities onto a homogeneous and isotropic background can be
addressed in this framework. We illustrate the latter by considering
homogeneous but anisotropic Bianchi--I cosmologies as perturbations around a
homogeneous and isotropic sector.
| [
{
"created": "Thu, 15 Feb 2007 20:18:55 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Dittrich",
"Bianca",
""
],
[
"Tambornino",
"Johannes",
""
]
] | We develop a gauge invariant canonical perturbation scheme for perturbations around symmetry reduced sectors in generally covariant theories, such as general relativity. The central objects of investigation are gauge invariant observables which encode the dynamics of the system. We apply this scheme to perturbations around a homogeneous and isotropic sector (cosmology) of general relativity. The background variables of this homogeneous and isotropic sector are treated fully dynamically which allows us to approximate the observables to arbitrary high order in a self--consistent and fully gauge invariant manner. Methods to compute these observables are given. The question of backreaction effects of inhomogeneities onto a homogeneous and isotropic background can be addressed in this framework. We illustrate the latter by considering homogeneous but anisotropic Bianchi--I cosmologies as perturbations around a homogeneous and isotropic sector. |
1811.03152 | Behnam Pourhassan | B. Pourhassan, K. Kokabi, Z. Sabery | Higher order corrected thermodynamics and statistics of
Kerr-Newman-Godel black hole | 16 pages, 8 Figures | Annals of Physics 399 (2018) 181 | 10.1016/j.aop.2018.10.011 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider the rotating charged G\"{o}del black hole and
study the effect of the higher order corrections of the entropy on the
thermodynamics and statistics quantities of the Kerr-Newman-G\"{o}del black
hole. The leading order correction is logarithmic while higher-order terms are
proportional to the inverse of the area of the black hole. We obtain modified
thermodynamics and statistics and find that correction terms are important in
the stability of the black hole.
| [
{
"created": "Sat, 3 Nov 2018 11:46:40 GMT",
"version": "v1"
}
] | 2018-11-09 | [
[
"Pourhassan",
"B.",
""
],
[
"Kokabi",
"K.",
""
],
[
"Sabery",
"Z.",
""
]
] | In this paper, we consider the rotating charged G\"{o}del black hole and study the effect of the higher order corrections of the entropy on the thermodynamics and statistics quantities of the Kerr-Newman-G\"{o}del black hole. The leading order correction is logarithmic while higher-order terms are proportional to the inverse of the area of the black hole. We obtain modified thermodynamics and statistics and find that correction terms are important in the stability of the black hole. |
gr-qc/9909095 | Fred Cooperstock I. | F.I. Cooperstock | Does a dynamical system lose energy by emitting gravitational waves? | Published in Modern Physics Letters A vol 14, no 23, 1531, 1999 Full
text available in the journal | Mod.Phys.Lett. A14 (1999) 1531 | 10.1142/S0217732399001620 | null | gr-qc | null | We note that Eddington's radiation damping calculation of a spinning rod
fails to account for the complete mass integral as given by Tolman. The missing
stress contributions precisely cancel the standard rate given by the
'quadrupole formula'. This indicates that while the usual 'kinetic' term can
properly account for dynamical changes in the source, the actual mass is
conserved. Hence gravity waves are not carriers of energy in vacuum. This
supports the hypothesis that energy including the gravitational contribution is
confined to regions of non-vanishing energy-momentum tensor $T_{ik}$.
PACS numbers: 04.20.Cv, 04.30.-w
| [
{
"created": "Thu, 30 Sep 1999 22:51:49 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Cooperstock",
"F. I.",
""
]
] | We note that Eddington's radiation damping calculation of a spinning rod fails to account for the complete mass integral as given by Tolman. The missing stress contributions precisely cancel the standard rate given by the 'quadrupole formula'. This indicates that while the usual 'kinetic' term can properly account for dynamical changes in the source, the actual mass is conserved. Hence gravity waves are not carriers of energy in vacuum. This supports the hypothesis that energy including the gravitational contribution is confined to regions of non-vanishing energy-momentum tensor $T_{ik}$. PACS numbers: 04.20.Cv, 04.30.-w |
gr-qc/0508123 | Abraham Harte | Abraham I. Harte | Self-forces on extended bodies in electrodynamics | 30 pages; significantly improved presentation; accepted for
publication in Phys. Rev. D | Phys.Rev.D73:065006,2006 | 10.1103/PhysRevD.73.065006 | null | gr-qc | null | In this paper, we study the bulk motion of a classical extended charge in
flat spacetime. A formalism developed by W. G. Dixon is used to determine how
the details of such a particle's internal structure influence its equations of
motion. We place essentially no restrictions (other than boundedness) on the
shape of the charge, and allow for inhomogeneity, internal currents,
elasticity, and spin. Even if the angular momentum remains small, many such
systems are found to be affected by large self-interaction effects beyond the
standard Lorentz-Dirac force. These are particularly significant if the
particle's charge density fails to be much greater than its 3-current density
(or vice versa) in the center-of-mass frame. Additional terms also arise in the
equations of motion if the dipole moment is too large, and when the
`center-of-electromagnetic mass' is far from the `center-of-bare mass' (roughly
speaking). These conditions are often quite restrictive. General equations of
motion were also derived under the assumption that the particle can only
interact with the radiative component of its self-field. These are much simpler
than the equations derived using the full retarded self-field; as are the
conditions required to recover the Lorentz-Dirac equation.
| [
{
"created": "Tue, 30 Aug 2005 08:51:34 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Jan 2006 04:44:44 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Harte",
"Abraham I.",
""
]
] | In this paper, we study the bulk motion of a classical extended charge in flat spacetime. A formalism developed by W. G. Dixon is used to determine how the details of such a particle's internal structure influence its equations of motion. We place essentially no restrictions (other than boundedness) on the shape of the charge, and allow for inhomogeneity, internal currents, elasticity, and spin. Even if the angular momentum remains small, many such systems are found to be affected by large self-interaction effects beyond the standard Lorentz-Dirac force. These are particularly significant if the particle's charge density fails to be much greater than its 3-current density (or vice versa) in the center-of-mass frame. Additional terms also arise in the equations of motion if the dipole moment is too large, and when the `center-of-electromagnetic mass' is far from the `center-of-bare mass' (roughly speaking). These conditions are often quite restrictive. General equations of motion were also derived under the assumption that the particle can only interact with the radiative component of its self-field. These are much simpler than the equations derived using the full retarded self-field; as are the conditions required to recover the Lorentz-Dirac equation. |
gr-qc/0101058 | J. Brian Pitts | J. Brian Pitts (The University of Texas at Austin) and W. C. Schieve
(The University of Texas at Austin) | Slightly Bimetric Gravitation | Minor editing, missing definition supplied, minor clarifications on
spinors of Ogievetskii and Polubarinov and on conformal flatness of
Robertson-Walker models | Gen.Rel.Grav. 33 (2001) 1319-1350 | 10.1023/A:1012005508094 | null | gr-qc hep-th | null | The inclusion of a flat metric tensor in gravitation permits the formulation
of a gravitational stress-energy tensor and the formal derivation of general
relativity from a linear theory in flat spacetime. Building on the works of
Kraichnan and Deser, we present such a derivation using universal coupling and
gauge invariance.
Next we slightly weaken the assumptions of universal coupling and gauge
invariance, obtaining a larger ``slightly bimetric'' class of theories, in
which the Euler-Lagrange equations depend only on a curved metric, matter
fields, and the determinant of the flat metric. The theories are equivalent to
generally covariant theories with an arbitrary cosmological constant and an
arbitrarily coupled scalar field, which can serve as an inflaton or dark
matter.
The question of the consistency of the null cone structures of the two
metrics is addressed. A difficulty for Logunov's massive gravitation on this
front is noted.
| [
{
"created": "Tue, 16 Jan 2001 06:55:52 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Jan 2001 05:30:24 GMT",
"version": "v2"
},
{
"created": "Thu, 16 Aug 2007 15:04:06 GMT",
"version": "v3"
}
] | 2015-06-25 | [
[
"Pitts",
"J. Brian",
"",
"The University of Texas at Austin"
],
[
"Schieve",
"W. C.",
"",
"The University of Texas at Austin"
]
] | The inclusion of a flat metric tensor in gravitation permits the formulation of a gravitational stress-energy tensor and the formal derivation of general relativity from a linear theory in flat spacetime. Building on the works of Kraichnan and Deser, we present such a derivation using universal coupling and gauge invariance. Next we slightly weaken the assumptions of universal coupling and gauge invariance, obtaining a larger ``slightly bimetric'' class of theories, in which the Euler-Lagrange equations depend only on a curved metric, matter fields, and the determinant of the flat metric. The theories are equivalent to generally covariant theories with an arbitrary cosmological constant and an arbitrarily coupled scalar field, which can serve as an inflaton or dark matter. The question of the consistency of the null cone structures of the two metrics is addressed. A difficulty for Logunov's massive gravitation on this front is noted. |
0811.4269 | Khedmat Atazadeh | K. Atazadeh, A. Khaleghi, H. R. Sepangi, Y. Tavakoli | Energy conditions in f(R) gravity and Brans-Dicke theories | 9 pages, 1 figure, to appear in IJMPD | Int.J.Mod.Phys.D18:1101-1111,2009 | 10.1142/S0218271809014972 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The equivalence between f(R) gravity and scalar-tensor theories is invoked to
study the null, strong, weak and dominant energy conditions in Brans-Dicke
theory. We consider the validity of the energy conditions in Brans-Dicke theory
by invoking the energy conditions derived from a generic f(R) theory. The
parameters involved are shown to be consistent with an accelerated expanding
universe.
| [
{
"created": "Wed, 26 Nov 2008 10:53:50 GMT",
"version": "v1"
}
] | 2009-08-25 | [
[
"Atazadeh",
"K.",
""
],
[
"Khaleghi",
"A.",
""
],
[
"Sepangi",
"H. R.",
""
],
[
"Tavakoli",
"Y.",
""
]
] | The equivalence between f(R) gravity and scalar-tensor theories is invoked to study the null, strong, weak and dominant energy conditions in Brans-Dicke theory. We consider the validity of the energy conditions in Brans-Dicke theory by invoking the energy conditions derived from a generic f(R) theory. The parameters involved are shown to be consistent with an accelerated expanding universe. |
gr-qc/9301007 | Yoshiaki Ohkuwa | Yoshiaki Ohkuwa | Decoherence Functional and Probability Interpretation | 9 pages, UCSBTH-92-40 and MMC-M-2 | Phys.Rev. D48 (1993) 1781-1784 | 10.1103/PhysRevD.48.1781 | null | gr-qc | null | We confirm that the diagonal elements of the Gell-Mann and Hartle's
decoherence decoherence functional are equal to the relative frequencies of the
results of many identical experiments, when a set of alternative histories
decoheres. We consider both cases of the pure and mixed initial states.
| [
{
"created": "Sat, 9 Jan 1993 20:32:38 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Ohkuwa",
"Yoshiaki",
""
]
] | We confirm that the diagonal elements of the Gell-Mann and Hartle's decoherence decoherence functional are equal to the relative frequencies of the results of many identical experiments, when a set of alternative histories decoheres. We consider both cases of the pure and mixed initial states. |
0907.2839 | Gil Jannes | Gil Jannes | Emergent gravity: the BEC paradigm | PhD thesis; 144 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study selected aspects of quantum gravity phenomenology inspired by the
gravitational analogy in Bose--Einstein condensates (BECs). We first review the
basic ideas and formalism of analogue gravity in BECs, with particular emphasis
on the possibility of simulating black holes. The non-relativistic,
'superluminal' modifications of the dispersion relation in a BEC beyond the
hydrodynamic limit make it a particularly interesting model for many scenarios
of quantum gravity phenomenology which consider a possible violation of local
Lorentz invariance at high energies. In particular, these modifications allow
the study of kinematical corrections that such quantum gravity scenarios could
impose on general relativity.
A simple (1+1)-dimensional acoustic black hole configuration in a BEC is
presented, and its dynamical stability and quasinormal mode spectrum are
studied. Then, an analysis is performed of the Hawking radiation for a
collapsing geometry in which a black hole is created. It is seen that the
superluminality of the dispersion relation leads to a frequency-dependence of
the horizon, which can cause strong qualitative and quantitative modifications
with respect to the standard (Lorentz-invariant) Hawking spectrum. We end with
some considerations related to the possibility of constructing a serious toy
model for Planck-scale gravity understood as an emergent phenomenon, based on
the condensed matter analogy. In particular, we discuss the problem of
diffeomorphism invariance in such a seemingly background-dependent approach and
indicate some possible ideas for how to recover the Einstein equations in the
adequate limit.
| [
{
"created": "Thu, 16 Jul 2009 13:41:33 GMT",
"version": "v1"
}
] | 2009-07-17 | [
[
"Jannes",
"Gil",
""
]
] | We study selected aspects of quantum gravity phenomenology inspired by the gravitational analogy in Bose--Einstein condensates (BECs). We first review the basic ideas and formalism of analogue gravity in BECs, with particular emphasis on the possibility of simulating black holes. The non-relativistic, 'superluminal' modifications of the dispersion relation in a BEC beyond the hydrodynamic limit make it a particularly interesting model for many scenarios of quantum gravity phenomenology which consider a possible violation of local Lorentz invariance at high energies. In particular, these modifications allow the study of kinematical corrections that such quantum gravity scenarios could impose on general relativity. A simple (1+1)-dimensional acoustic black hole configuration in a BEC is presented, and its dynamical stability and quasinormal mode spectrum are studied. Then, an analysis is performed of the Hawking radiation for a collapsing geometry in which a black hole is created. It is seen that the superluminality of the dispersion relation leads to a frequency-dependence of the horizon, which can cause strong qualitative and quantitative modifications with respect to the standard (Lorentz-invariant) Hawking spectrum. We end with some considerations related to the possibility of constructing a serious toy model for Planck-scale gravity understood as an emergent phenomenon, based on the condensed matter analogy. In particular, we discuss the problem of diffeomorphism invariance in such a seemingly background-dependent approach and indicate some possible ideas for how to recover the Einstein equations in the adequate limit. |
1910.00416 | Mark D. Roberts | Mark D. Roberts | The Lanczos Potential for Bianchi Spacetime | 19 pages, 79 equations, high equation to text ratio | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The form and application of the Lanczos potential for Bianchi spacetime are
studied. The Lanczos potential is found in some specific cases then the general
case studied. It leads to two coupled first order partial differential
equations which although they so far have not been solved in general can be
solved for many configurations. The application is to cosmic energetics: in
other words to the study of the energy of the gravitational and other fields in
the Universe.
| [
{
"created": "Sat, 28 Sep 2019 13:16:11 GMT",
"version": "v1"
}
] | 2019-10-02 | [
[
"Roberts",
"Mark D.",
""
]
] | The form and application of the Lanczos potential for Bianchi spacetime are studied. The Lanczos potential is found in some specific cases then the general case studied. It leads to two coupled first order partial differential equations which although they so far have not been solved in general can be solved for many configurations. The application is to cosmic energetics: in other words to the study of the energy of the gravitational and other fields in the Universe. |
2010.14527 | LSC P&P Committee | R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, A. Adams,
C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N.
Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, S. Akcay, G. Allen, A.
Allocca, P. A. Altin, A. Amato, S. Anand, A. Ananyeva, S. B. Anderson, W. G.
Anderson, S. V. Angelova, S. Ansoldi, J. M. Antelis, S. Antier, S. Appert, K.
Arai, M. C. Araya, J. S. Areeda, M. Ar\`ene, N. Arnaud, S. M. Aronson, K. G.
Arun, Y. Asali, S. Ascenzi, G. Ashton, S. M. Aston, P. Astone, F. Aubin, P.
Aufmuth, K. AultONeal, C. Austin, V. Avendano, S. Babak, F. Badaracco, M. K.
M. Bader, S. Bae, A. M. Baer, S. Bagnasco, J. Baird, M. Ball, G. Ballardin,
S. W. Ballmer, A. Bals, A. Balsamo, G. Baltus, S. Banagiri, D. Bankar, R. S.
Bankar, J. C. Barayoga, C. Barbieri, B. C. Barish, D. Barker, P. Barneo, S.
Barnum, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, D. Barta, J. Bartlett,
I. Bartos, R. Bassiri, A. Basti, M. Bawaj, J. C. Bayley, M. Bazzan, B. R.
Becher, B. B\'ecsy, V. M. Bedakihale, M. Bejger, I. Belahcene, D. Beniwal, M.
G. Benjamin, T. F. Bennett, J. D. Bentley, F. Bergamin, B. K. Berger, G.
Bergmann, S. Bernuzzi, C. P. L. Berry, D. Bersanetti, A. Bertolini, J.
Betzwieser, R. Bhandare, A. V. Bhandari, D. Bhattacharjee, J. Bidler, I. A.
Bilenko, G. Billingsley, R. Birney, O. Birnholtz, S. Biscans, M. Bischi, S.
Biscoveanu, A. Bisht, M. Bitossi, M.-A. Bizouard, J. K. Blackburn, J.
Blackman, C. D. Blair, D. G. Blair, R. M. Blair, O. Blanch, F. Bobba, N.
Bode, M. Boer, Y. Boetzel, G. Bogaert, M. Boldrini, F. Bondu, R. Bonnand, E.
Bonilla, P. Booker, B. A. Boom, R. Bork, V. Boschi, S. Bose, V. Bossilkov, V.
Boudart, Y. Bouffanais, A. Bozzi, C. Bradaschia, P. R. Brady, A. Bramley, M.
Branchesi, J. E. Brau, M. Breschi, T. Briant, J. H. Briggs, F. Brighenti, A.
Brillet, M. Brinkmann, P. Brockill, A. F. Brooks, J. Brooks, D. D. Brown, S.
Brunett, G. Bruno, R. Bruntz, A. Buikema, T. Bulik, H. J. Bulten, A.
Buonanno, R. Buscicchio, D. Buskulic, R. L. Byer, M. Cabero, L. Cadonati, M.
Caesar, G. Cagnoli, C. Cahillane, J. Calder\'on Bustillo, J. D. Callaghan, T.
A. Callister, E. Calloni, J. B. Camp, M. Canepa, K. C. Cannon, H. Cao, J.
Cao, G. Carapella, F. Carbognani, M. F. Carney, M. Carpinelli, G. Carullo, T.
L. Carver, J. Casanueva Diaz, C. Casentini, S. Caudill, M. Cavagli\`a, F.
Cavalier, R. Cavalieri, G. Cella, P. Cerd\'a-Dur\'an, E. Cesarini, W. Chaibi,
K. Chakravarti, C.-L. Chan, C. Chan, K. Chandra, P. Chanial, S. Chao, P.
Charlton, E. A. Chase, E. Chassande-Mottin, D. Chatterjee, D. Chattopadhyay,
M. Chaturvedi, K. Chatziioannou, A. Chen, H. Y. Chen, X. Chen, Y. Chen, H.-P.
Cheng, C. K. Cheong, H. Y. Chia, F. Chiadini, R. Chierici, A. Chincarini, A.
Chiummo, G. Cho, H. S. Cho, M. Cho, S. Choate, N. Christensen, Q. Chu, S.
Chua, K. W. Chung, S. Chung, G. Ciani, P. Ciecielag, M. Cie\'slar, M.
Cifaldi, A. A. Ciobanu, R. Ciolfi, F. Cipriano, A. Cirone, F. Clara, E. N.
Clark, J. A. Clark, L. Clarke, P. Clearwater, S. Clesse, F. Cleva, E. Coccia,
P.-F. Cohadon, D. E. Cohen, M. Colleoni, C. G. Collette, C. Collins, M.
Colpi, M. Constancio Jr., L. Conti, S. J. Cooper, P. Corban, T. R. Corbitt,
I. Cordero-Carri\'on, S. Corezzi, K. R. Corley, N. Cornish, D. Corre, A.
Corsi, S. Cortese, C. A. Costa, R. Cotesta, M. W. Coughlin, S. B. Coughlin,
J.-P. Coulon, S. T. Countryman, B. Cousins, P. Couvares, P. B. Covas, D. M.
Coward, M. J. Cowart, D. C. Coyne, R. Coyne, J. D. E. Creighton, T. D.
Creighton, M. Croquette, S. G. Crowder, J.R. Cudell, T. J. Cullen, A.
Cumming, R. Cummings, L. Cunningham, E. Cuoco, M. Curylo, T. Dal Canton, G.
D\'alya, A. Dana, L. M. DaneshgaranBajastani, B. D'Angelo, B. Danila, S. L.
Danilishin, S. D'Antonio, K. Danzmann, C. Darsow-Fromm, A. Dasgupta, L. E. H.
Datrier, V. Dattilo, I. Dave, M. Davier, G. S. Davies, D. Davis, E. J. Daw,
R. Dean, D. DeBra, M. Deenadayalan, J. Degallaix, M. De Laurentis, S.
Del\'eglise, V. Del Favero, F. De Lillo, N. De Lillo, W. Del Pozzo, L. M.
DeMarchi, F. De Matteis, V. D'Emilio, N. Demos, T. Denker, T. Dent, A.
Depasse, R. De Pietri, R. De Rosa, C. De Rossi, R. DeSalvo, O. de Varona, S.
Dhurandhar, M. C. D\'iaz, M. Diaz-Ortiz Jr., N. A. Didio, T. Dietrich, L. Di
Fiore, C. DiFronzo, C. Di Giorgio, F. Di Giovanni, M. Di Giovanni, T. Di
Girolamo, A. Di Lieto, B. Ding, S. Di Pace, I. Di Palma, F. Di Renzo, A. K.
Divakarla, A. Dmitriev, Z. Doctor, L. D'Onofrio, F. Donovan, K. L. Dooley, S.
Doravari, I. Dorrington, T. P. Downes, M. Drago, J. C. Driggers, Z. Du, J.-G.
Ducoin, P. Dupej, O. Durante, D. D'Urso, P.-A. Duverne, S. E. Dwyer, P. J.
Easter, G. Eddolls, B. Edelman, T. B. Edo, O. Edy, A. Effler, J. Eichholz, S.
S. Eikenberry, M. Eisenmann, R. A. Eisenstein, A. Ejlli, L. Errico, R. C.
Essick, H. Estell\'es, D. Estevez, Z. B. Etienne, T. Etzel, M. Evans, T. M.
Evans, B. E. Ewing, V. Fafone, H. Fair, S. Fairhurst, X. Fan, A. M. Farah, S.
Farinon, B. Farr, W. M. Farr, E. J. Fauchon-Jones, M. Favata, M. Fays, M.
Fazio, J. Feicht, M. M. Fejer, F. Feng, E. Fenyvesi, D. L. Ferguson, A.
Fernandez-Galiana, I. Ferrante, T. A. Ferreira, F. Fidecaro, P. Figura, I.
Fiori, D. Fiorucci, M. Fishbach, R. P. Fisher, J. M. Fishner, R. Fittipaldi,
M. Fitz-Axen, V. Fiumara, R. Flaminio, E. Floden, E. Flynn, H. Fong, J. A.
Font, P. W. F. Forsyth, J.-D. Fournier, S. Frasca, F. Frasconi, Z. Frei, A.
Freise, R. Frey, V. Frey, P. Fritschel, V. V. Frolov, G. G. Fronz\'e, P.
Fulda, M. Fyffe, H. A. Gabbard, B. U. Gadre, S. M. Gaebel, J. R. Gair, J.
Gais, S. Galaudage, R. Gamba, D. Ganapathy, A. Ganguly, S. G. Gaonkar, B.
Garaventa, C. Garc\'ia-Quir\'os, F. Garufi, B. Gateley, S. Gaudio, V.
Gayathri, G. Gemme, A. Gennai, D. George, J. George, R. N. George, L.
Gergely, S. Ghonge, Abhirup Ghosh, Archisman Ghosh, S. Ghosh, B. Giacomazzo,
L. Giacoppo, J. A. Giaime, K. D. Giardina, D. R. Gibson, C. Gier, K. Gill, P.
Giri, J. Glanzer, A. E. Gleckl, P. Godwin, E. Goetz, R. Goetz, N. Gohlke, B.
Goncharov, G. Gonz\'alez, A. Gopakumar, S. E. Gossan, M. Gosselin, R. Gouaty,
B. Grace, A. Grado, M. Granata, V. Granata, A. Grant, S. Gras, P. Grassia, C.
Gray, R. Gray, G. Greco, A. C. Green, R. Green, E. M. Gretarsson, H. L.
Griggs, G. Grignani, A. Grimaldi, E. Grimes, S. J. Grimm, H. Grote, S.
Grunewald, P. Gruning, J. G. Guerrero, G. M. Guidi, A. R. Guimaraes, G.
Guix\'e, H. K. Gulati, Y. Guo, Anchal Gupta, Anuradha Gupta, P. Gupta, E. K.
Gustafson, R. Gustafson, F. Guzman, L. Haegel, O. Halim, E. D. Hall, E. Z.
Hamilton, G. Hammond, M. Haney, M. M. Hanke, J. Hanks, C. Hanna, M. D.
Hannam, O. A. Hannuksela, O. Hannuksela, H. Hansen, T. J. Hansen, J. Hanson,
T. Harder, T. Hardwick, K. Haris, J. Harms, G. M. Harry, I. W. Harry, D.
Hartwig, R. K. Hasskew, C.-J. Haster, K. Haughian, F. J. Hayes, J. Healy, A.
Heidmann, M. C. Heintze, J. Heinze, J. Heinzel, H. Heitmann, F. Hellman, P.
Hello, A. F. Helmling-Cornell, G. Hemming, M. Hendry, I. S. Heng, E. Hennes,
J. Hennig, M. H. Hennig, F. Hernandez Vivanco, M. Heurs, S. Hild, P. Hill, A.
S. Hines, S. Hochheim, E. Hofgard, D. Hofman, J. N. Hohmann, A. M. Holgado,
N. A. Holland, I. J. Hollows, Z. J. Holmes, K. Holt, D. E. Holz, P. Hopkins,
C. Horst, J. Hough, E. J. Howell, C. G. Hoy, D. Hoyland, Y. Huang, M. T.
H\"ubner, A. D. Huddart, E. A. Huerta, B. Hughey, V. Hui, S. Husa, S. H.
Huttner, B. M. Hutzler, R. Huxford, T. Huynh-Dinh, B. Idzkowski, A. Iess, S.
Imperato, H. Inchauspe, C. Ingram, G. Intini, M. Isi, B. R. Iyer, V.
JaberianHamedan, T. Jacqmin, S. J. Jadhav, S. P. Jadhav, A. L. James, K.
Jani, K. Janssens, N. N. Janthalur, P. Jaranowski, D. Jariwala, R. Jaume, A.
C. Jenkins, M. Jeunon, J. Jiang, G. R. Johns, N. K. Johnson-McDaniel, A. W.
Jones, D. I. Jones, J. D. Jones, P. Jones, R. Jones, R. J. G. Jonker, L. Ju,
J. Junker, C. V. Kalaghatgi, V. Kalogera, B. Kamai, S. Kandhasamy, G. Kang,
J. B. Kanner, S. J. Kapadia, D. P. Kapasi, C. Karathanasis, S. Karki, R.
Kashyap, M. Kasprzack, W. Kastaun, S. Katsanevas, E. Katsavounidis, W.
Katzman, K. Kawabe, F. K\'ef\'elian, D. Keitel, J. S. Key, S. Khadka, F. Y.
Khalili, I. Khan, S. Khan, E. A. Khazanov, N. Khetan, M. Khursheed, N.
Kijbunchoo, C. Kim, G. J. Kim, J. C. Kim, K. Kim, W. S. Kim, Y.-M. Kim, C.
Kimball, P. J. King, M. Kinley-Hanlon, R. Kirchhoff, J. S. Kissel, L.
Kleybolte, S. Klimenko, T. D. Knowles, E. Knyazev, P. Koch, S. M.
Koehlenbeck, G. Koekoek, S. Koley, M. Kolstein, K. Komori, V. Kondrashov, A.
Kontos, N. Koper, M. Korobko, W. Z. Korth, M. Kovalam, D. B. Kozak, C.
Kr\"amer, V. Kringel, N. V. Krishnendu, A. Kr\'olak, G. Kuehn, A. Kumar, P.
Kumar, Rahul Kumar, Rakesh Kumar, K. Kuns, S. Kwang, B. D. Lackey, D. Laghi,
E. Lalande, T. L. Lam, A. Lamberts, M. Landry, B. B. Lane, R. N. Lang, J.
Lange, B. Lantz, R. K. Lanza, I. La Rosa, A. Lartaux-Vollard, P. D. Lasky, M.
Laxen, A. Lazzarini, C. Lazzaro, P. Leaci, S. Leavey, Y. K. Lecoeuche, H. M.
Lee, H. W. Lee, J. Lee, K. Lee, J. Lehmann, E. Leon, N. Leroy, N. Letendre,
Y. Levin, A. Li, J. Li, K. J. L. Li, T. G. F. Li, X. Li, F. Linde, S. D.
Linker, J. N. Linley, T. B. Littenberg, J. Liu, X. Liu, M.
Llorens-Monteagudo, R. K. L. Lo, A. Lockwood, L. T. London, A. Longo, M.
Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. D. Lough, C. O. Lousto, G.
Lovelace, H. L\"uck, D. Lumaca, A. P. Lundgren, Y. Ma, R. Macas, M. MacInnis,
D. M. Macleod, I. A. O. MacMillan, A. Macquet, I. Maga\~na Hernandez, F.
Maga\~na-Sandoval, C. Magazz\`u, R. M. Magee, E. Majorana, I. Maksimovic, S.
Maliakal, A. Malik, N. Man, V. Mandic, V. Mangano, G. L. Mansell, M. Manske,
M. Mantovani, M. Mapelli, F. Marchesoni, F. Marion, S. M\'arka, Z. M\'arka,
C. Markakis, A. S. Markosyan, A. Markowitz, E. Maros, A. Marquina, S. Marsat,
F. Martelli, I. W. Martin, R. M. Martin, M. Martinez, V. Martinez, D. V.
Martynov, H. Masalehdan, K. Mason, E. Massera, A. Masserot, T. J. Massinger,
M. Masso-Reid, S. Mastrogiovanni, A. Matas, M. Mateu-Lucena, F. Matichard, M.
Matiushechkina, N. Mavalvala, E. Maynard, J. J. McCann, R. McCarthy, D. E.
McClelland, S. McCormick, L. McCuller, S. C. McGuire, C. McIsaac, J. McIver,
D. J. McManus, T. McRae, S. T. McWilliams, D. Meacher, G. D. Meadors, M.
Mehmet, A. K. Mehta, A. Melatos, D. A. Melchor, G. Mendell, A.
Menendez-Vazquez, R. A. Mercer, L. Mereni, K. Merfeld, E. L. Merilh, J. D.
Merritt, M. Merzougui, S. Meshkov, C. Messenger, C. Messick, R. Metzdorff, P.
M. Meyers, F. Meylahn, A. Mhaske, A. Miani, H. Miao, I. Michaloliakos, C.
Michel, H. Middleton, L. Milano, A. L. Miller, M. Millhouse, J. C. Mills, E.
Milotti, M. C. Milovich-Goff, O. Minazzoli, Y. Minenkov, Ll. M. Mir, A.
Mishkin, C. Mishra, T. Mistry, S. Mitra, V. P. Mitrofanov, G. Mitselmakher,
R. Mittleman, G. Mo, K. Mogushi, S. R. P. Mohapatra, S. R. Mohite, I. Molina,
M. Molina-Ruiz, M. Mondin, M. Montani, C. J. Moore, D. Moraru, F. Morawski,
G. Moreno, S. Morisaki, B. Mours, C. M. Mow-Lowry, S. Mozzon, F. Muciaccia,
Arunava Mukherjee, D. Mukherjee, Soma Mukherjee, Subroto Mukherjee, N.
Mukund, A. Mullavey, J. Munch, E. A. Mu\~niz, P. G. Murray, S. L. Nadji, A.
Nagar, I. Nardecchia, L. Naticchioni, R. K. Nayak, B. F. Neil, J. Neilson, G.
Nelemans, T. J. N. Nelson, M. Nery, A. Neunzert, A. H. Nitz, K. Y. Ng, S. Ng,
C. Nguyen, P. Nguyen, T. Nguyen, S. A. Nichols, S. Nissanke, F. Nocera, M.
Noh, C. North, D. Nothard, L. K. Nuttall, J. Oberling, B. D. O'Brien, J.
O'Dell, G. Oganesyan, G. H. Ogin, J. J. Oh, S. H. Oh, F. Ohme, H. Ohta, M. A.
Okada, C. Olivetto, P. Oppermann, R. J. Oram, B. O'Reilly, R. G. Ormiston, L.
F. Ortega, R. O'Shaughnessy, S. Ossokine, C. Osthelder, D. J. Ottaway, H.
Overmier, B. J. Owen, A. E. Pace, G. Pagano, M. A. Page, G. Pagliaroli, A.
Pai, S. A. Pai, J. R. Palamos, O. Palashov, C. Palomba, H. Pan, P. K. Panda,
T. H. Pang, C. Pankow, F. Pannarale, B. C. Pant, F. Paoletti, A. Paoli, A.
Paolone, W. Parker, D. Pascucci, A. Pasqualetti, R. Passaquieti, D.
Passuello, M. Patel, B. Patricelli, E. Payne, T. C. Pechsiri, M. Pedraza, M.
Pegoraro, A. Pele, S. Penn, A. Perego, C. J. Perez, C. P\'erigois, A.
Perreca, S. Perri\`es, J. Petermann, D. Petterson, H. P. Pfeiffer, K. A.
Pham, K. S. Phukon, O. J. Piccinni, M. Pichot, M. Piendibene, F.
Piergiovanni, L. Pierini, V. Pierro, G. Pillant, F. Pilo, L. Pinard, I. M.
Pinto, K. Piotrzkowski, M. Pirello, M. Pitkin, E. Placidi, W. Plastino, C.
Pluchar, R. Poggiani, E. Polini, D. Y. T. Pong, S. Ponrathnam, P. Popolizio,
E. K. Porter, A. Poverman, J. Powell, M. Pracchia, A. K. Prajapati, K.
Prasai, R. Prasanna, G. Pratten, T. Prestegard, M. Principe, G. A. Prodi, L.
Prokhorov, P. Prosposito, L. Prudenzi, A. Puecher, M. Punturo, F. Puosi, P.
Puppo, M. P\"urrer, H. Qi, V. Quetschke, P. J. Quinonez, R. Quitzow-James, F.
J. Raab, G. Raaijmakers, H. Radkins, N. Radulesco, P. Raffai, H. Rafferty, S.
X. Rail, S. Raja, C. Rajan, B. Rajbhandari, M. Rakhmanov, K. E. Ramirez, T.
D. Ramirez, A. Ramos-Buades, J. Rana, K. Rao, P. Rapagnani, U. D. Rapol, B.
Ratto, V. Raymond, M. Razzano, J. Read, T. Regimbau, L. Rei, S. Reid, D. H.
Reitze, P. Rettegno, F. Ricci, C. J. Richardson, J. W. Richardson, L.
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Robertson, F. Robinet, A. Rocchi, J. A. Rocha, S. Rodriguez, R. D.
Rodriguez-Soto, L. Rolland, J. G. Rollins, V. J. Roma, M. Romanelli, R.
Romano, C. L. Romel, A. Romero, I. M. Romero-Shaw, J. H. Romie, S. Ronchini,
C. A. Rose, D. Rose, K. Rose, M. J. B. Rosell, D. Rosi\'nska, S. G. Rosofsky,
M. P. Ross, S. Rowan, S. J. Rowlinson, Santosh Roy, Soumen Roy, P. Ruggi, K.
Ryan, S. Sachdev, T. Sadecki, J. Sadiq, M. Sakellariadou, O. S. Salafia, L.
Salconi, M. Saleem, A. Samajdar, E. J. Sanchez, J. H. Sanchez, L. E. Sanchez,
N. Sanchis-Gual, J. R. Sanders, L. Sandles, K. A. Santiago, E. Santos, T. R.
Saravanan, N. Sarin, B. Sassolas, B. S. Sathyaprakash, O. Sauter, R. L.
Savage, V. Savant, D. Sawant, S. Sayah, D. Schaetzl, P. Schale, M. Scheel, J.
Scheuer, A. Schindler-Tyka, P. Schmidt, R. Schnabel, R. M. S. Schofield, A.
Sch\"onbeck, E. Schreiber, B. W. Schulte, B. F. Schutz, O. Schwarm, E.
Schwartz, J. Scott, S. M. Scott, M. Seglar-Arroyo, E. Seidel, D. Sellers, A.
S. Sengupta, N. Sennett, D. Sentenac, V. Sequino, A. Sergeev, Y. Setyawati,
T. Shaffer, M. S. Shahriar, S. Sharifi, A. Sharma, P. Sharma, P. Shawhan, H.
Shen, M. Shikauchi, R. Shink, D. H. Shoemaker, D. M. Shoemaker, K. Shukla, S.
ShyamSundar, M. Sieniawska, D. Sigg, L. P. Singer, D. Singh, N. Singh, A.
Singha, A. Singhal, A. M. Sintes, V. Sipala, V. Skliris, B. J. J. Slagmolen,
T. J. Slaven-Blair, J. Smetana, J. R. Smith, R. J. E. Smith, S. N. Somala, E.
J. Son, K. Soni, S. Soni, B. Sorazu, V. Sordini, F. Sorrentino, N.
Sorrentino, R. Soulard, T. Souradeep, E. Sowell, A. P. Spencer, M. Spera, A.
K. Srivastava, V. Srivastava, K. Staats, C. Stachie, D. A. Steer, J.
Steinhoff, M. Steinke, J. Steinlechner, S. Steinlechner, D. Steinmeyer, S. P.
Stevenson, G. Stolle-McAllister, D. J. Stops, M. Stover, K. A. Strain, G.
Stratta, A. Strunk, R. Sturani, A. L. Stuver, J. S\"udbeck, S. Sudhagar, V.
Sudhir, H. G. Suh, T. Z. Summerscales, H. Sun, L. Sun, S. Sunil, A. Sur, J.
Suresh, P. J. Sutton, B. L. Swinkels, M. J. Szczepa\'nczyk, M. Tacca, S. C.
Tait, C. Talbot, A. J. Tanasijczuk, D. B. Tanner, D. Tao, A. Tapia, E. N.
Tapia San Martin, J. D. Tasson, R. Taylor, R. Tenorio, L. Terkowski, M. P.
Thirugnanasambandam, L. M. Thomas, M. Thomas, P. Thomas, J. E. Thompson, S.
R. Thondapu, K. A. Thorne, E. Thrane, Shubhanshu Tiwari, Srishti Tiwari, V.
Tiwari, K. Toland, A. E. Tolley, M. Tonelli, Z. Tornasi, A. Torres-Forn\'e,
C. I. Torrie, I. Tosta e Melo, D. T\"oyr\"a, A. T. Tran, A. Trapananti, F.
Travasso, G. Traylor, M. C. Tringali, A. Tripathee, A. Trovato, R. J.
Trudeau, D. S. Tsai, K. W. Tsang, M. Tse, R. Tso, L. Tsukada, D. Tsuna, T.
Tsutsui, M. Turconi, A. S. Ubhi, R. P. Udall, K. Ueno, D. Ugolini, C. S.
Unnikrishnan, A. L. Urban, S. A. Usman, A. C. Utina, H. Vahlbruch, G.
Vajente, A. Vajpeyi, G. Valdes, M. Valentini, V. Valsan, N. van Bakel, M. van
Beuzekom, J. F. J. van den Brand, C. Van Den Broeck, D. C. Vander-Hyde, L.
van der Schaaf, J. V. van Heijningen, M. Vardaro, A. F. Vargas, V. Varma, S.
Vass, M. Vas\'uth, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, K.
Venkateswara, J. Venneberg, G. Venugopalan, D. Verkindt, Y. Verma, D. Veske,
F. Vetrano, A. Vicer\'e, A. D. Viets, A. Vijaykumar, V. Villa-Ortega, J.-Y.
Vinet, S. Vitale, T. Vo, H. Vocca, C. Vorvick, S. P. Vyatchanin, A. R. Wade,
L. E. Wade, M. Wade, R. C. Walet, M. Walker, G. S. Wallace, L. Wallace, S.
Walsh, J. Z. Wang, S. Wang, W. H. Wang, Y. F. Wang, R. L. Ward, J. Warner, M.
Was, N. Y. Washington, J. Watchi, B. Weaver, L. Wei, M. Weinert, A. J.
Weinstein, R. Weiss, F. Wellmann, L. Wen, P. We{\ss}els, J. W. Westhouse, K.
Wette, J. T. Whelan, D. D. White, L. V. White, B. F. Whiting, C. Whittle, D.
M. Wilken, D. Williams, M. J. Williams, A. R. Williamson, J. L. Willis, B.
Willke, D. J. Wilson, M. H. Wimmer, W. Winkler, C. C. Wipf, G. Woan, J.
Woehler, J. K. Wofford, I. C. F. Wong, J. Wrangel, J. L. Wright, D. S. Wu, D.
M. Wysocki, L. Xiao, H. Yamamoto, L. Yang, Y. Yang, Z. Yang, M. J. Yap, D. W.
Yeeles, A. Yoon, Hang Yu, Haocun Yu, S. H. R. Yuen, A. Zadro\.zny, M.
Zanolin, T. Zelenova, J.-P. Zendri, M. Zevin, J. Zhang, L. Zhang, R. Zhang,
T. Zhang, C. Zhao, G. Zhao, Y. Zheng, M. Zhou, Z. Zhou, X. J. Zhu, A. B.
Zimmerman, Y. Zlochower, M. E. Zucker, J. Zweizig | GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During
the First Half of the Third Observing Run | This version updates with minor revisions to typographical errors. We
would also like to call attention to the updated parameter estimation samples
data release here: https://dcc.ligo.org/LIGO-P2000223/public | Phys. Rev. X 11, 021053 (2021) | 10.1103/PhysRevX.11.021053 | P2000061 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We report on gravitational wave discoveries from compact binary coalescences
detected by Advanced LIGO and Advanced Virgo in the first half of the third
observing run (O3a) between 1 April 2019 15:00 UTC and 1 October 2019 15:00. By
imposing a false-alarm-rate threshold of two per year in each of the four
search pipelines that constitute our search, we present 39 candidate
gravitational wave events. At this threshold, we expect a contamination
fraction of less than 10%. Of these, 26 candidate events were reported
previously in near real-time through GCN Notices and Circulars; 13 are reported
here for the first time. The catalog contains events whose sources are black
hole binary mergers up to a redshift of ~0.8, as well as events whose
components could not be unambiguously identified as black holes or neutron
stars. For the latter group, we are unable to determine the nature based on
estimates of the component masses and spins from gravitational wave data alone.
The range of candidate events which are unambiguously identified as binary
black holes (both objects $\geq 3~M_\odot$) is increased compared to GWTC-1,
with total masses from $\sim 14~M_\odot$ for GW190924_021846 to $\sim
150~M_\odot$ for GW190521. For the first time, this catalog includes binary
systems with significantly asymmetric mass ratios, which had not been observed
in data taken before April 2019. We also find that 11 of the 39 events detected
since April 2019 have positive effective inspiral spins under our default prior
(at 90% credibility), while none exhibit negative effective inspiral spin.
Given the increased sensitivity of Advanced LIGO and Advanced Virgo, the
detection of 39 candidate events in ~26 weeks of data (~1.5 per week) is
consistent with GWTC-1.
| [
{
"created": "Tue, 27 Oct 2020 18:01:31 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Feb 2021 16:31:07 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Mar 2021 18:36:29 GMT",
"version": "v3"
}
] | 2021-06-15 | [
[
"Abbott",
"R.",
""
],
[
"Abbott",
"T. D.",
""
],
[
"Abraham",
"S.",
""
],
[
"Acernese",
"F.",
""
],
[
"Ackley",
"K.",
""
],
[
"Adams",
"A.",
""
],
[
"Adams",
"C.",
""
],
[
"Adhikari",
"R. X.",
... | We report on gravitational wave discoveries from compact binary coalescences detected by Advanced LIGO and Advanced Virgo in the first half of the third observing run (O3a) between 1 April 2019 15:00 UTC and 1 October 2019 15:00. By imposing a false-alarm-rate threshold of two per year in each of the four search pipelines that constitute our search, we present 39 candidate gravitational wave events. At this threshold, we expect a contamination fraction of less than 10%. Of these, 26 candidate events were reported previously in near real-time through GCN Notices and Circulars; 13 are reported here for the first time. The catalog contains events whose sources are black hole binary mergers up to a redshift of ~0.8, as well as events whose components could not be unambiguously identified as black holes or neutron stars. For the latter group, we are unable to determine the nature based on estimates of the component masses and spins from gravitational wave data alone. The range of candidate events which are unambiguously identified as binary black holes (both objects $\geq 3~M_\odot$) is increased compared to GWTC-1, with total masses from $\sim 14~M_\odot$ for GW190924_021846 to $\sim 150~M_\odot$ for GW190521. For the first time, this catalog includes binary systems with significantly asymmetric mass ratios, which had not been observed in data taken before April 2019. We also find that 11 of the 39 events detected since April 2019 have positive effective inspiral spins under our default prior (at 90% credibility), while none exhibit negative effective inspiral spin. Given the increased sensitivity of Advanced LIGO and Advanced Virgo, the detection of 39 candidate events in ~26 weeks of data (~1.5 per week) is consistent with GWTC-1. |
gr-qc/0502075 | Fabrizio Canfora | F. Canfora, G. Vilasi | PP-waves, Israel's Matching conditions, Brane-world scenarios and BPS
states in gravity | 16 pages, no figures. Accepted for pubblication on Classical and
Quantum Gravity | Class.Quant.Grav.22:1193-1205,2005 | 10.1088/0264-9381/22/7/001 | null | gr-qc hep-th | null | The matching between two 4-dimensional PP-waves is discussed by using
Israel's matching conditions. Physical consequences on the dynamics of (cosmic)
strings are analyzed. The extension to space-time of arbitrary dimension is
discussed and some interesting features related to the brane world scenario,
BPS states in gravity and Dirac-like quantization conditions are briefly
described.
| [
{
"created": "Wed, 16 Feb 2005 08:07:14 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Canfora",
"F.",
""
],
[
"Vilasi",
"G.",
""
]
] | The matching between two 4-dimensional PP-waves is discussed by using Israel's matching conditions. Physical consequences on the dynamics of (cosmic) strings are analyzed. The extension to space-time of arbitrary dimension is discussed and some interesting features related to the brane world scenario, BPS states in gravity and Dirac-like quantization conditions are briefly described. |
gr-qc/0408061 | Volodymyr Pelykh | V. Pelykh | Knot points of double--covariant system of elliptic equations and
preferred frames in general relativity | 10 pages | J.Phys.A35:8135-8144,2002 | 10.1088/0305-4470/35/38/313 | null | gr-qc | null | The elliptic system of equations, which is general-covariant and locally
SU(2)-covariant, is investigated. The new condition of the Dirichlet problem
solvability and the condition of zeros absence for solutions are obtained for
this system, which contains in particular case the Sen-Witten equation. On this
basis it is proved the existence of the wide class of hypersurfaces, in all
points of which there exists a correspondence between the Sen-Witten spinor
field and three-frame, which generalizes the Nester orthoframe. The Nester
special orthoframe also exists on a certain subclass containing not only the
maximal hypersurfaces.
| [
{
"created": "Wed, 18 Aug 2004 13:40:21 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Pelykh",
"V.",
""
]
] | The elliptic system of equations, which is general-covariant and locally SU(2)-covariant, is investigated. The new condition of the Dirichlet problem solvability and the condition of zeros absence for solutions are obtained for this system, which contains in particular case the Sen-Witten equation. On this basis it is proved the existence of the wide class of hypersurfaces, in all points of which there exists a correspondence between the Sen-Witten spinor field and three-frame, which generalizes the Nester orthoframe. The Nester special orthoframe also exists on a certain subclass containing not only the maximal hypersurfaces. |
gr-qc/0005121 | Robert D. Klauber | Robert D. Klauber | Non-time-orthogonal Reference Frames in the Theory of Relativity | 11 pages including 4 figs, appendix, references, and title page
submitted for publication | null | null | null | gr-qc | null | A simple, though rarely considered, thought experiment on relativistic
rotation is described in which internal inconsistencies in the theory of
relativity seem to arise. These apparent inconsistencies are resolved by
appropriate insight into the nature, and unique properties, of the
non-time-orthogonal rotating frame. The analysis also explains a heretofore
inexplicable experimental result.
| [
{
"created": "Sun, 28 May 2000 20:01:16 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Klauber",
"Robert D.",
""
]
] | A simple, though rarely considered, thought experiment on relativistic rotation is described in which internal inconsistencies in the theory of relativity seem to arise. These apparent inconsistencies are resolved by appropriate insight into the nature, and unique properties, of the non-time-orthogonal rotating frame. The analysis also explains a heretofore inexplicable experimental result. |
2007.04995 | William C. C. Lima | William C. C. Lima | Graviton backreaction on the local cosmological expansion in slow-roll
inflation | 41 pages. Reformulated version, with some intermediary steps moved to
the appendix, some sections made more concise and improved discussions.
Results unchanged; matches published version | Class. Quantum Grav. 38, 135015 (2021) | 10.1088/1361-6382/abfaeb | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the graviton one-loop correction to the expectation value of the
local expansion rate in slow-roll inflation, with both slow-roll parameters
finite. The calculation is based on a recent method to explicitly construct
gauge-invariant observables in perturbative quantum gravity at all orders in
perturbation theory, and it is particularly suited in cases of
highly-symmetrical space-time backgrounds. Our analysis adds to recent
calculations of that correction in de Sitter space-time and in single-field
inflation with constant deceleration. In the former case a vanishing one-loop
correction was found, while in the latter the quantum backreaction produces a
secular effect that accelerates the expansion. The quantum correction we
describe here produces a finite secular effect that can either accelerated or
decelerate the background expansion, depending on the value of the slow-roll
parameters.
| [
{
"created": "Thu, 9 Jul 2020 18:00:01 GMT",
"version": "v1"
},
{
"created": "Sun, 19 Jul 2020 19:01:38 GMT",
"version": "v2"
},
{
"created": "Fri, 16 Oct 2020 15:06:35 GMT",
"version": "v3"
},
{
"created": "Thu, 3 Jun 2021 13:47:30 GMT",
"version": "v4"
}
] | 2021-06-04 | [
[
"Lima",
"William C. C.",
""
]
] | We compute the graviton one-loop correction to the expectation value of the local expansion rate in slow-roll inflation, with both slow-roll parameters finite. The calculation is based on a recent method to explicitly construct gauge-invariant observables in perturbative quantum gravity at all orders in perturbation theory, and it is particularly suited in cases of highly-symmetrical space-time backgrounds. Our analysis adds to recent calculations of that correction in de Sitter space-time and in single-field inflation with constant deceleration. In the former case a vanishing one-loop correction was found, while in the latter the quantum backreaction produces a secular effect that accelerates the expansion. The quantum correction we describe here produces a finite secular effect that can either accelerated or decelerate the background expansion, depending on the value of the slow-roll parameters. |
gr-qc/0502094 | Giovanni Montani | Emanuele Alesci and Giovanni Montani | Can be gravitational waves markers for an extra-dimension? | 5 pages, two figure, to appear on Int. Journ. Mod. Phys. D | Int.J.Mod.Phys. D14 (2005) 923-932 | 10.1142/S0218271805006717 | null | gr-qc | null | The main issue of the present letter is to fix specific features (which turn
out being independent of extradimension size) of gravitational waves generated
before a dimensional compactification process. Valuable is the possibility to
detect our prediction from gravitational wave experiment without high energy
laboratory investigation. In particular we show how gravitational waves can
bring information on the number of Universe dimensions. Within the framework of
Kaluza-Klein hypotheses, a different morphology arises between waves generated
before than the compactification process settled down and ordinary
4-dimensional waves. In the former case the scalar and tensor degrees of
freedom can not be resolved. As a consequence if were detected gravitational
waves having the feature here predicted (anomalous polarization amplitudes),
then they would be reliable markers for the existence of an extra dimension.
| [
{
"created": "Tue, 22 Feb 2005 15:24:58 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Alesci",
"Emanuele",
""
],
[
"Montani",
"Giovanni",
""
]
] | The main issue of the present letter is to fix specific features (which turn out being independent of extradimension size) of gravitational waves generated before a dimensional compactification process. Valuable is the possibility to detect our prediction from gravitational wave experiment without high energy laboratory investigation. In particular we show how gravitational waves can bring information on the number of Universe dimensions. Within the framework of Kaluza-Klein hypotheses, a different morphology arises between waves generated before than the compactification process settled down and ordinary 4-dimensional waves. In the former case the scalar and tensor degrees of freedom can not be resolved. As a consequence if were detected gravitational waves having the feature here predicted (anomalous polarization amplitudes), then they would be reliable markers for the existence of an extra dimension. |
gr-qc/0609091 | Thomas Sotiriou | Theocharis A. Apostolatos, Thomas P. Sotiriou | Measuring mass moments and electromagnetic moments of a massive,
axisymmetric body, through gravitational waves | Talk given by T. A. A. at Recent Advances in Astronomy and
Astrophysics, Lixourion, Kefallinia island, Greece, 8-11 Sep 2005 | AIP Conf. Proc. 848, 677 (2006) | 10.1063/1.2348046 | null | gr-qc | null | The electrovacuum around a rotating massive body with electric charge density
is described by its multipole moments (mass moments, mass-current moments,
electric moments, and magnetic moments). A small uncharged test particle
orbiting around such a body moves on geodesics if gravitational radiation is
ignored. The waves emitted by the small body carry information about the
geometry of the central object, and hence, in principle, we can infer all its
multipole moments. Due to its axisymmetry the source is characterized now by
four families of scalar multipole moments: its mass moments $M_l$, its
mass-current moments $S_l$, its electrical moments $E_l$ and its magnetic
moments $H_l$, where $l=0,1,2,...$. Four measurable quantities, the energy
emitted by gravitational waves per logarithmic interval of frequency, the
precession of the periastron (assuming almost circular orbits), the precession
of the orbital plane (assuming almost equatorial orbits), and the number of
cycles emitted per logarithmic interval of frequency, are presented as power
series of the newtonian orbital velocity of the test body. The power series
coefficients are simple polynomials of the various moments.
| [
{
"created": "Thu, 21 Sep 2006 13:07:17 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Apostolatos",
"Theocharis A.",
""
],
[
"Sotiriou",
"Thomas P.",
""
]
] | The electrovacuum around a rotating massive body with electric charge density is described by its multipole moments (mass moments, mass-current moments, electric moments, and magnetic moments). A small uncharged test particle orbiting around such a body moves on geodesics if gravitational radiation is ignored. The waves emitted by the small body carry information about the geometry of the central object, and hence, in principle, we can infer all its multipole moments. Due to its axisymmetry the source is characterized now by four families of scalar multipole moments: its mass moments $M_l$, its mass-current moments $S_l$, its electrical moments $E_l$ and its magnetic moments $H_l$, where $l=0,1,2,...$. Four measurable quantities, the energy emitted by gravitational waves per logarithmic interval of frequency, the precession of the periastron (assuming almost circular orbits), the precession of the orbital plane (assuming almost equatorial orbits), and the number of cycles emitted per logarithmic interval of frequency, are presented as power series of the newtonian orbital velocity of the test body. The power series coefficients are simple polynomials of the various moments. |
2105.10638 | Ayan Banerjee | Grigoris Panotopoulos, Takol Tangphati and Ayan Banerjee | Electrically charged compact stars with an interacting quark equation of
state | 8 pages, 3 figures | null | 10.1016/j.cjph.2021.10.027 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the properties of non-rotating, electrically charged strange
quark stars in four-dimensional Einstein-Maxwell theory. For quark matter we
adopt the well-motivated quantum chromodynamics (QCD) equation-of-state, while
for the charge density we assume it is proportional to the mass density. The
system of coupled structure equations are integrated numerically, and we
compute the mass, the radius as well as the total electric charge of the stars.
Moreover, we perform a detailed numerical study of the effect of electric
charge using the interacting quark equation-of-state. We find that stars as
heavy as two solar masses can be supported, and that the highest radius and
highest mass of the stars increase with the charge density.
| [
{
"created": "Sat, 22 May 2021 04:51:38 GMT",
"version": "v1"
}
] | 2022-05-04 | [
[
"Panotopoulos",
"Grigoris",
""
],
[
"Tangphati",
"Takol",
""
],
[
"Banerjee",
"Ayan",
""
]
] | We investigate the properties of non-rotating, electrically charged strange quark stars in four-dimensional Einstein-Maxwell theory. For quark matter we adopt the well-motivated quantum chromodynamics (QCD) equation-of-state, while for the charge density we assume it is proportional to the mass density. The system of coupled structure equations are integrated numerically, and we compute the mass, the radius as well as the total electric charge of the stars. Moreover, we perform a detailed numerical study of the effect of electric charge using the interacting quark equation-of-state. We find that stars as heavy as two solar masses can be supported, and that the highest radius and highest mass of the stars increase with the charge density. |
2206.05481 | B. S. Ratanpal | Ankita Jangid, B. S. Ratanpal, K Venkataratnam Kamma | Anisotropic Compact Star Model on Finch-Skea Spacetime | 9 figures, 1 table and 7 pages | null | 10.1134/S0202289323020068 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this study, we demonstrate a new anisotropic solution to the Einstein
field equations in Finch-Skea spacetime. The physical features of stellar
configuration are studied in previous investigations. We create a model that
meets all physical plausibility conditions for a variety of stars and plot
graphs for \textbf{4U 1820-30}.
| [
{
"created": "Sat, 11 Jun 2022 09:54:08 GMT",
"version": "v1"
},
{
"created": "Sat, 10 Sep 2022 06:29:54 GMT",
"version": "v2"
}
] | 2023-06-28 | [
[
"Jangid",
"Ankita",
""
],
[
"Ratanpal",
"B. S.",
""
],
[
"Kamma",
"K Venkataratnam",
""
]
] | In this study, we demonstrate a new anisotropic solution to the Einstein field equations in Finch-Skea spacetime. The physical features of stellar configuration are studied in previous investigations. We create a model that meets all physical plausibility conditions for a variety of stars and plot graphs for \textbf{4U 1820-30}. |
1506.03280 | Krzysztof A. Meissner | Krzysztof A. Meissner and Pawel Nurowski | Conformal transformations and the beginning of the Universe | 4 pages | Phys. Rev. D 95, 084016 (2017) | 10.1103/PhysRevD.95.084016 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that two consecutive Universes with positive cosmological constants
filled with perfect fluids and conformal to the positive-spatial-curvature FLRW
metric by an analytic conformal transformation have the following features
implied by the Einstein equations: a) the fluids can only belong to 4 classes
(radiation, dust and two other classes with negative pressures corresponding to
a gas of strings and a gas of domain walls), b) the field equations on both
sides of the future/eternity hypersurface exhibit certain duality with the
Einstein Universe at the background, and c) both eons (one at the end, and the
other at the beginning) are almost critical, so that the future eon is
dominated by radiation and resembles the beginning of our Universe.
| [
{
"created": "Wed, 10 Jun 2015 12:54:14 GMT",
"version": "v1"
}
] | 2017-04-19 | [
[
"Meissner",
"Krzysztof A.",
""
],
[
"Nurowski",
"Pawel",
""
]
] | We show that two consecutive Universes with positive cosmological constants filled with perfect fluids and conformal to the positive-spatial-curvature FLRW metric by an analytic conformal transformation have the following features implied by the Einstein equations: a) the fluids can only belong to 4 classes (radiation, dust and two other classes with negative pressures corresponding to a gas of strings and a gas of domain walls), b) the field equations on both sides of the future/eternity hypersurface exhibit certain duality with the Einstein Universe at the background, and c) both eons (one at the end, and the other at the beginning) are almost critical, so that the future eon is dominated by radiation and resembles the beginning of our Universe. |
0904.0815 | Lorenzo Sindoni | Stefano Liberati, Lorenzo Sindoni, Sebastiano Sonego | Linking the trans-Planckian and the information loss problems in black
hole physics | 10 pages, 2 figures. Replaced with the version to be published in
General Relativity and Gravitation | Gen.Rel.Grav.42:1139-1152,2010 | 10.1007/s10714-009-0899-2 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The trans-Planckian and information loss problems are usually discussed in
the literature as separate issues concerning the nature of Hawking radiation.
Here we instead argue that they are intimately linked, and can be understood as
"two sides of the same coin" once it is accepted that general relativity is an
effective field theory.
| [
{
"created": "Mon, 6 Apr 2009 18:47:22 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Oct 2009 08:52:04 GMT",
"version": "v2"
}
] | 2014-11-18 | [
[
"Liberati",
"Stefano",
""
],
[
"Sindoni",
"Lorenzo",
""
],
[
"Sonego",
"Sebastiano",
""
]
] | The trans-Planckian and information loss problems are usually discussed in the literature as separate issues concerning the nature of Hawking radiation. Here we instead argue that they are intimately linked, and can be understood as "two sides of the same coin" once it is accepted that general relativity is an effective field theory. |
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