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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0902.3746 | Orlando Luongo | Orlando Luongo and Carmine Autieri | Scale-Free model for governing universe dynamics | 7 pages, 4 figures | null | 10.1209/0295-5075/90/39001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the effects of scale-free model on cosmology, providing, in
this way, a statistical background in the framework of general relativity. In
order to discuss properties and time evolution of some relevant universe
dynamical parameters (cosmographic parameters), such as $H(t)$ (Hubble
parameter), $q(t)$ (deceleration parameter), $j(t)$ (jerk parameter) and $s(t)$
(snap parameter), which are well re-defined in the framework of scale-free
model, we analyze a comparison between WMAP data. Hence the basic purpose of
the work is to consider this statistical interpretation of mass distribution of
universe, in order to have a mass density $\rho$ dynamics, not inferred from
Friedmann equations, via scale factor $a(t)$. This model, indeed, has been used
also to explain a possible origin and a viable explanation of cosmological
constant, which assumes a statistical interpretation without the presence of
extended theories of gravity; hence the problem of dark energy could be
revisited in the context of a classical probability distribution of mass, which
is, in particular, for the scale-free model, $P(k)\sim k^{-\gamma}$, with
$2<\gamma<3$. The $\Lambda$CDM model becomes, with these considerations, a
consequence of the particular statistics together with the use of general
relativity.
| [
{
"created": "Sat, 21 Feb 2009 16:37:46 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Feb 2009 19:31:30 GMT",
"version": "v2"
},
{
"created": "Sat, 25 Apr 2009 15:20:31 GMT",
"version": "v3"
}
] | 2015-05-13 | [
[
"Luongo",
"Orlando",
""
],
[
"Autieri",
"Carmine",
""
]
] | We investigate the effects of scale-free model on cosmology, providing, in this way, a statistical background in the framework of general relativity. In order to discuss properties and time evolution of some relevant universe dynamical parameters (cosmographic parameters), such as $H(t)$ (Hubble parameter), $q(t)$ (deceleration parameter), $j(t)$ (jerk parameter) and $s(t)$ (snap parameter), which are well re-defined in the framework of scale-free model, we analyze a comparison between WMAP data. Hence the basic purpose of the work is to consider this statistical interpretation of mass distribution of universe, in order to have a mass density $\rho$ dynamics, not inferred from Friedmann equations, via scale factor $a(t)$. This model, indeed, has been used also to explain a possible origin and a viable explanation of cosmological constant, which assumes a statistical interpretation without the presence of extended theories of gravity; hence the problem of dark energy could be revisited in the context of a classical probability distribution of mass, which is, in particular, for the scale-free model, $P(k)\sim k^{-\gamma}$, with $2<\gamma<3$. The $\Lambda$CDM model becomes, with these considerations, a consequence of the particular statistics together with the use of general relativity. |
gr-qc/9611062 | BoB | Roberto Casadio (Dipartimento di Fisica, Universita' di Bologna and
I.N.F.N., Sezione di Bologna, Italy) | Semiclassical Collapse of a Sphere of Dust and Hawking Radiation | LaTeX, 4 pages, talk given at the "Second conference on constrained
dynamics and quantum gravity", Santa Margherita Ligure, Italy, 17-21
September 1996. To appear in the proceedings | Nucl.Phys.Proc.Suppl. 57 (1997) 177-180 | 10.1016/S0920-5632(97)00367-8 | null | gr-qc | null | The independent dynamical variables of a collapsing homogeneous sphere of
dust are canonically quantised and coupled equations describing matter (dust)
and gravitation are obtained. The conditions for the validity of the adiabatic
(Born-Oppenheimer) and semiclassical approximations are derived. On neglecting
back-reaction effects, it is also shown that in the vicinity of the horizon and
inside the dust the Wightman function for a conformal scalar field coupled to a
monopole emitter is thermal at the characteristic Hawking temperature.
| [
{
"created": "Tue, 26 Nov 1996 08:51:32 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Casadio",
"Roberto",
"",
"Dipartimento di Fisica, Universita' di Bologna and\n I.N.F.N., Sezione di Bologna, Italy"
]
] | The independent dynamical variables of a collapsing homogeneous sphere of dust are canonically quantised and coupled equations describing matter (dust) and gravitation are obtained. The conditions for the validity of the adiabatic (Born-Oppenheimer) and semiclassical approximations are derived. On neglecting back-reaction effects, it is also shown that in the vicinity of the horizon and inside the dust the Wightman function for a conformal scalar field coupled to a monopole emitter is thermal at the characteristic Hawking temperature. |
gr-qc/0501024 | Charles Wang | Charles H.-T. Wang | Conformal geometrodynamics: True degrees of freedom in a truly canonical
structure | 8 pages, REVTeX, Final version with improved presentation to appear
in PRD | Phys.Rev. D71 (2005) 124026 | 10.1103/PhysRevD.71.124026 | null | gr-qc | null | The standard geometrodynamics is transformed into a theory of conformal
geometrodynamics by extending the ADM phase space for canonical general
relativity to that consisting of York's mean exterior curvature time, conformal
three-metric and their momenta. Accordingly, an additional constraint is
introduced, called the conformal constraint. In terms of the new canonical
variables, a diffeomorphism constraint is derived from the original momentum
constraint. The Hamiltonian constraint then takes a new form. It turns out to
be the sum of an expression that previously appeared in the literature and
extra terms quadratic in the conformal constraint. The complete set of the
conformal, diffeomorphism and Hamiltonian constraints are shown to be of first
class through the explicit construction of their Poisson brackets. The extended
algebra of constraints has as subalgebras the Dirac algebra for the
deformations and Lie algebra for the conformorphism transformations of the
spatial hypersurface. This is followed by a discussion of potential
implications of the presented theory on the Dirac constraint quantization of
general relativity. An argument is made to support the use of the York time in
formulating the unitary functional evolution of quantum gravity. Finally, the
prospect of future work is briefly outlined.
| [
{
"created": "Sat, 8 Jan 2005 19:18:05 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Jan 2005 14:50:00 GMT",
"version": "v2"
},
{
"created": "Fri, 4 Mar 2005 21:59:52 GMT",
"version": "v3"
},
{
"created": "Sun, 5 Jun 2005 20:06:33 GMT",
"version": "v4"
}
] | 2007-05-23 | [
[
"Wang",
"Charles H. -T.",
""
]
] | The standard geometrodynamics is transformed into a theory of conformal geometrodynamics by extending the ADM phase space for canonical general relativity to that consisting of York's mean exterior curvature time, conformal three-metric and their momenta. Accordingly, an additional constraint is introduced, called the conformal constraint. In terms of the new canonical variables, a diffeomorphism constraint is derived from the original momentum constraint. The Hamiltonian constraint then takes a new form. It turns out to be the sum of an expression that previously appeared in the literature and extra terms quadratic in the conformal constraint. The complete set of the conformal, diffeomorphism and Hamiltonian constraints are shown to be of first class through the explicit construction of their Poisson brackets. The extended algebra of constraints has as subalgebras the Dirac algebra for the deformations and Lie algebra for the conformorphism transformations of the spatial hypersurface. This is followed by a discussion of potential implications of the presented theory on the Dirac constraint quantization of general relativity. An argument is made to support the use of the York time in formulating the unitary functional evolution of quantum gravity. Finally, the prospect of future work is briefly outlined. |
2311.04682 | Abbas Sherif | Abbas M. Sherif | On the existence of conformal Killing horizons in LRS spacetimes | 16 pages, no figure, minor typos corrected, accepted for publication
in Gen. Relativ. Gravit | Gen Relativ Gravit 56, 15 (2024) | 10.1007/s10714-024-03197-w | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Let $M$ be a locally rotationally symmetric spacetime, and $\xi^a$ a
conformal Killing vector for the metric on $M$, lying in the subspace spanned
by the unit timelike direction and the preferred spatial direction, and with
non-constant components. Under the assumption that the divergence of $\xi^a$
has no critical point in $M$, we obtain the necessary and sufficient condition
for $\xi^a$ to generate a conformal Killing horizon. It is shown that $\xi^a$
generates a conformal Killing horizon if and only if either of the components
(which coincide on the horizon) is constant along its orbits. That is, a
conformal Killing horizon can be realized as the set of critical points of the
variation of the component(s) of the conformal Killing vector along its orbits.
Using this result, a simple mechanism is provided by which to determine if an
arbitrary vector in an expanding LRS spacetime is a conformal Killing vector
that generates a conformal Killing horizon. In specializing the case for which
$\xi^a$ is a special conformal Killing vector, provided that the gradient of
the divergence of $\xi^a$ is non-null, it is shown that LRS spacetimes cannot
admit a special conformal Killing vector field, thereby ruling out conformal
Killing horizons generated by such vector fields.
| [
{
"created": "Wed, 8 Nov 2023 13:42:10 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Jan 2024 04:05:26 GMT",
"version": "v2"
}
] | 2024-02-02 | [
[
"Sherif",
"Abbas M.",
""
]
] | Let $M$ be a locally rotationally symmetric spacetime, and $\xi^a$ a conformal Killing vector for the metric on $M$, lying in the subspace spanned by the unit timelike direction and the preferred spatial direction, and with non-constant components. Under the assumption that the divergence of $\xi^a$ has no critical point in $M$, we obtain the necessary and sufficient condition for $\xi^a$ to generate a conformal Killing horizon. It is shown that $\xi^a$ generates a conformal Killing horizon if and only if either of the components (which coincide on the horizon) is constant along its orbits. That is, a conformal Killing horizon can be realized as the set of critical points of the variation of the component(s) of the conformal Killing vector along its orbits. Using this result, a simple mechanism is provided by which to determine if an arbitrary vector in an expanding LRS spacetime is a conformal Killing vector that generates a conformal Killing horizon. In specializing the case for which $\xi^a$ is a special conformal Killing vector, provided that the gradient of the divergence of $\xi^a$ is non-null, it is shown that LRS spacetimes cannot admit a special conformal Killing vector field, thereby ruling out conformal Killing horizons generated by such vector fields. |
gr-qc/0609090 | Spiros Cotsakis | John Miritzis, Spiros Cotsakis | Singularities of varying light speed cosmologies | 7 pages, 2 figures, uses iop style files, to appear in the
Proceedings of the Greek Relativity Meeting NEB12, June 29-July 2, 2006,
Nauplia, Greece | J.Phys.Conf.Ser.68:012019,2007 | 10.1088/1742-6596/68/1/012019 | null | gr-qc | null | We study the possible singularities of isotropic cosmological models that
have a varying speed of light as well as a varying gravitational constant. The
field equations typically reduce to two dimensional systems which are then
analyzed both by dynamical systems techniques in phase space and by applying
the method of asymptotic splittings. In the general case we find initially
expanding closed models which recollapse to a future singularity and open
universes that are eternally expanding towards the future. The precise nature
of the singularities is also discussed.
| [
{
"created": "Thu, 21 Sep 2006 11:59:18 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Miritzis",
"John",
""
],
[
"Cotsakis",
"Spiros",
""
]
] | We study the possible singularities of isotropic cosmological models that have a varying speed of light as well as a varying gravitational constant. The field equations typically reduce to two dimensional systems which are then analyzed both by dynamical systems techniques in phase space and by applying the method of asymptotic splittings. In the general case we find initially expanding closed models which recollapse to a future singularity and open universes that are eternally expanding towards the future. The precise nature of the singularities is also discussed. |
1105.5086 | Mehrdad Farhoudi Dr. | S.M. M. Rasouli, Mehrdad Farhoudi and Hamid R. Sepangi | Anisotropic Cosmological Model in Modified Brans--Dicke Theory | 20 pages, 4 figures | Class. Quant. Grav. 28 (No. 15) (2011) 155004 | 10.1088/0264-9381/28/15/155004 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been shown that four dimensional Brans-Dicke theory with effective
matter field and self interacting potential can be achieved from vacuum 5D BD
field equations, where we refer to as modified Brans-Dicke theory (MBDT). We
investigate a generalized Bianchi type I anisotropic cosmology in 5D BD theory,
and by employing obtained formalism, we derive induced-matter on any 4D
hypersurface in context of the MBDT. We illustrate that if the usual spatial
scale factors are functions of time while scale factor of extra dimension is
constant, and scalar field depends on time and fifth coordinate, then in
general, one will encounter inconsistencies in field equations. Then, we assume
the scale factors and scalar field depend on time and extra coordinate as
separated variables in power law forms. Hence, we find a few classes of
solutions in 5D spacetime through which, we probe the one which leads to a
generalized Kasner relations among Kasner parameters. The induced scalar
potential is found to be in power law or in logarithmic form, however, for
constant scaler field and even when scalar field only depends on fifth
coordinate, it vanishes. The conservation law is indeed valid in this MBDT
approach for derived induced energy momentum tensor (EMT). We proceed our
investigations for a few cosmological quantities, where for simplicity we
assume metric and scalar field are functions of time. Hence, the EMT satisfies
barotropic equation of state, and the model indicates that constant mean Hubble
parameter is not allowed. Thus, by appealing to variation of Hubble parameter,
we assume a fixed deceleration parameter, and set evolution of quantities with
respect to the fixed deceleration, BD coupling and state parameters. The WEC
allows a shrinking extra dimension for decelerating expanding universe that, in
the constant scalar field, evolves same as flat FRW spacetime in GR.
| [
{
"created": "Wed, 25 May 2011 16:55:42 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Rasouli",
"S. M. M.",
""
],
[
"Farhoudi",
"Mehrdad",
""
],
[
"Sepangi",
"Hamid R.",
""
]
] | It has been shown that four dimensional Brans-Dicke theory with effective matter field and self interacting potential can be achieved from vacuum 5D BD field equations, where we refer to as modified Brans-Dicke theory (MBDT). We investigate a generalized Bianchi type I anisotropic cosmology in 5D BD theory, and by employing obtained formalism, we derive induced-matter on any 4D hypersurface in context of the MBDT. We illustrate that if the usual spatial scale factors are functions of time while scale factor of extra dimension is constant, and scalar field depends on time and fifth coordinate, then in general, one will encounter inconsistencies in field equations. Then, we assume the scale factors and scalar field depend on time and extra coordinate as separated variables in power law forms. Hence, we find a few classes of solutions in 5D spacetime through which, we probe the one which leads to a generalized Kasner relations among Kasner parameters. The induced scalar potential is found to be in power law or in logarithmic form, however, for constant scaler field and even when scalar field only depends on fifth coordinate, it vanishes. The conservation law is indeed valid in this MBDT approach for derived induced energy momentum tensor (EMT). We proceed our investigations for a few cosmological quantities, where for simplicity we assume metric and scalar field are functions of time. Hence, the EMT satisfies barotropic equation of state, and the model indicates that constant mean Hubble parameter is not allowed. Thus, by appealing to variation of Hubble parameter, we assume a fixed deceleration parameter, and set evolution of quantities with respect to the fixed deceleration, BD coupling and state parameters. The WEC allows a shrinking extra dimension for decelerating expanding universe that, in the constant scalar field, evolves same as flat FRW spacetime in GR. |
2109.10236 | Paola Zizzi | Paola Zizzi | Quantum Holography from Fermion Fields | 18 pages, 1 figure | Quantum Rep. 2021, 3, 576 | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | We demonstrate, in the context of Loop Quantum Gravity, the Quantum
Holographic Principle, according to which the area of the boundary surface
enclosing a region of space encodes a qubit per Planck unit. To this aim, we
introduce fermion fields in the bulk, whose boundary surface is the
two-dimensional sphere. The doubling of the fermionic degrees of freedom and
the use of the Bogoljubov transformations lead to pairs of spin network's edges
piercing the boundary surface with double punctures, giving rise to pixels of
area encoding a qubit. The proof is also valid in the case of a fuzzy sphere.
| [
{
"created": "Mon, 20 Sep 2021 11:30:34 GMT",
"version": "v1"
}
] | 2021-09-22 | [
[
"Zizzi",
"Paola",
""
]
] | We demonstrate, in the context of Loop Quantum Gravity, the Quantum Holographic Principle, according to which the area of the boundary surface enclosing a region of space encodes a qubit per Planck unit. To this aim, we introduce fermion fields in the bulk, whose boundary surface is the two-dimensional sphere. The doubling of the fermionic degrees of freedom and the use of the Bogoljubov transformations lead to pairs of spin network's edges piercing the boundary surface with double punctures, giving rise to pixels of area encoding a qubit. The proof is also valid in the case of a fuzzy sphere. |
1601.06397 | Apimook Watcharangkool | Mairi Sakellariadou and Apimook Watcharangkool | Linear stability of noncommutative spectral geometry | 14 pages | Phys. Rev. D 93, 064034 (2016) | 10.1103/PhysRevD.93.064034 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the spectral action within the context of a 4-dimensional
manifold with torsion and show that, in the vacuum case, the equations of
motion reduce to Einstein's equations, securing the linear stability of the
theory. To subsequently investigate the nonvacuum case, we consider the
spectral action of an almost commutative torsion geometry and show that the
Hamiltonian is bounded from below, a result which guarantees the linear
stability of the theory.
| [
{
"created": "Sun, 24 Jan 2016 15:27:16 GMT",
"version": "v1"
}
] | 2016-03-23 | [
[
"Sakellariadou",
"Mairi",
""
],
[
"Watcharangkool",
"Apimook",
""
]
] | We consider the spectral action within the context of a 4-dimensional manifold with torsion and show that, in the vacuum case, the equations of motion reduce to Einstein's equations, securing the linear stability of the theory. To subsequently investigate the nonvacuum case, we consider the spectral action of an almost commutative torsion geometry and show that the Hamiltonian is bounded from below, a result which guarantees the linear stability of the theory. |
1605.08404 | Vasilis Oikonomou | V.K. Oikonomou | Some Classes of Gravitational Shock Waves from Higher Order Theories of
Gravity | Major revision, refs added, typos corrected | null | 10.1007/s10509-017-3014-2 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the gravitational shock wave generated by a massless high energy
particle in the context of higher order gravities of the form $F(R,R_{\mu
\nu}R^{\mu \nu},R_{\mu \nu \alpha \beta}R^{\mu \nu \alpha \beta})$. In the case
of $F(R)$ gravity, we investigate the gravitational shock wave solutions
corresponding to various cosmologically viable gravities, and as we demonstrate
the solutions are rescaled versions of the Einstein-Hilbert gravity solution.
Interestingly enough, other higher order gravities result to the general
relativistic solution, except for some specific gravities of the form $F(R_{\mu
\nu}R^{\mu \nu})$ and $F(R,R_{\mu \nu}R^{\mu \nu})$, which we study in detail.
In addition, when realistic Gauss-Bonnet gravities of the form
$R+F(\mathcal{G})$ are considered, the gravitational shock wave solutions are
identical to the general relativistic solution. Finally, the singularity
structure of the gravitational shock waves solutions is studied, and it is
shown that the effect of higher order gravities makes the singularities milder
in comparison to the general relativistic solutions, and in some particular
cases the singularities seem to be absent.
| [
{
"created": "Thu, 26 May 2016 18:50:04 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Jun 2016 13:59:14 GMT",
"version": "v2"
}
] | 2017-01-25 | [
[
"Oikonomou",
"V. K.",
""
]
] | We study the gravitational shock wave generated by a massless high energy particle in the context of higher order gravities of the form $F(R,R_{\mu \nu}R^{\mu \nu},R_{\mu \nu \alpha \beta}R^{\mu \nu \alpha \beta})$. In the case of $F(R)$ gravity, we investigate the gravitational shock wave solutions corresponding to various cosmologically viable gravities, and as we demonstrate the solutions are rescaled versions of the Einstein-Hilbert gravity solution. Interestingly enough, other higher order gravities result to the general relativistic solution, except for some specific gravities of the form $F(R_{\mu \nu}R^{\mu \nu})$ and $F(R,R_{\mu \nu}R^{\mu \nu})$, which we study in detail. In addition, when realistic Gauss-Bonnet gravities of the form $R+F(\mathcal{G})$ are considered, the gravitational shock wave solutions are identical to the general relativistic solution. Finally, the singularity structure of the gravitational shock waves solutions is studied, and it is shown that the effect of higher order gravities makes the singularities milder in comparison to the general relativistic solutions, and in some particular cases the singularities seem to be absent. |
gr-qc/0505084 | Sergio del Campo | Sergio del Campo (PUCV) and Ramon Herrera (UNAB) | Extended closed inflationary universes | 9 pages, 4 figures, accepted by Class. Quant. Grav | Class.Quant.Grav. 22 (2005) 2687-2700 | 10.1088/0264-9381/22/13/012 | null | gr-qc astro-ph hep-th | null | In this paper we study a type of model for closed inflationary universe
models using the Jordan-Brans-Dicke theory. Herein we determine and
characterize the existence of $\Omega>$1, together with the period of
inflation. We have found that our model, which takes into account a
Jordan-Brans-Dicke type of theory, is less restrictive than the one used in
Einstein's theory of general relativity. Our results are compared to those
found in Einstein's theory of Relativity.
| [
{
"created": "Tue, 17 May 2005 20:19:31 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"del Campo",
"Sergio",
"",
"PUCV"
],
[
"Herrera",
"Ramon",
"",
"UNAB"
]
] | In this paper we study a type of model for closed inflationary universe models using the Jordan-Brans-Dicke theory. Herein we determine and characterize the existence of $\Omega>$1, together with the period of inflation. We have found that our model, which takes into account a Jordan-Brans-Dicke type of theory, is less restrictive than the one used in Einstein's theory of general relativity. Our results are compared to those found in Einstein's theory of Relativity. |
2105.06968 | Alesandro Santos | A. F. Santos, S. C. Ulhoa, E. P. Spaniol and Faqir C. Khanna | On Gravitational Stefan-Boltzmann Law and Casimir Effect in FRW Universe | 12 pages, accepted for publication in General Relativity and
Gravitation | null | 10.1007/s10714-021-02826-y | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Both Stefan-Boltzmann law and the Casimir effect, in a universe described by
the FRW metric with zero curvature, are calculated. These effects are described
by Thermo Field Dynamics (TFD). The gravitational energy-momentum tensor is
defined in the context of Teleparallel Equivalent to General Relativity (TEGR).
Each of the two effects gives a consistent prediction with what is observed on
a cosmological scale. One of the effect establishes a minimum range for the
deceleration parameter. While another leads to the conclusion that a possible
cosmological constant has a very small order of magnitude.
| [
{
"created": "Fri, 14 May 2021 17:17:58 GMT",
"version": "v1"
}
] | 2022-04-20 | [
[
"Santos",
"A. F.",
""
],
[
"Ulhoa",
"S. C.",
""
],
[
"Spaniol",
"E. P.",
""
],
[
"Khanna",
"Faqir C.",
""
]
] | Both Stefan-Boltzmann law and the Casimir effect, in a universe described by the FRW metric with zero curvature, are calculated. These effects are described by Thermo Field Dynamics (TFD). The gravitational energy-momentum tensor is defined in the context of Teleparallel Equivalent to General Relativity (TEGR). Each of the two effects gives a consistent prediction with what is observed on a cosmological scale. One of the effect establishes a minimum range for the deceleration parameter. While another leads to the conclusion that a possible cosmological constant has a very small order of magnitude. |
1501.06184 | Marjan Elmizadeh | M. Elmizadeh | Conformal Auxiliary "Massless" Spin-2 Field in de Sitter Space | arXiv admin note: text overlap with arXiv:1105.3060 by other authors | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Respecting the group theoretical approach, it is discussed that the linear
conformal gravity can be written in terms of a mixed symmetry tensor field of
rank-3 \cite{binegar}. Following this path, related field equation was obtained
in de Sitter space \cite{fatemi}. It was proved that this kind of tensor field
in de Sitter background associates with two unitary irreducible representations
(UIR) of the de Sitter group. The important fact is that one of the them has a
flat limit, namely, in zero curvature coincides to the UIR of Poincar\'{e}
group which has been studied in Ref \cite{rahbar}.
However, the second one which is named as auxiliary field, becomes
significant in the study of conformal gravity in de Sitter background. In this
paper we will study the second representation in details by finding its
solutions and also the conformally invariant two-point function.
| [
{
"created": "Sun, 25 Jan 2015 17:00:40 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Feb 2015 16:33:30 GMT",
"version": "v2"
}
] | 2015-02-06 | [
[
"Elmizadeh",
"M.",
""
]
] | Respecting the group theoretical approach, it is discussed that the linear conformal gravity can be written in terms of a mixed symmetry tensor field of rank-3 \cite{binegar}. Following this path, related field equation was obtained in de Sitter space \cite{fatemi}. It was proved that this kind of tensor field in de Sitter background associates with two unitary irreducible representations (UIR) of the de Sitter group. The important fact is that one of the them has a flat limit, namely, in zero curvature coincides to the UIR of Poincar\'{e} group which has been studied in Ref \cite{rahbar}. However, the second one which is named as auxiliary field, becomes significant in the study of conformal gravity in de Sitter background. In this paper we will study the second representation in details by finding its solutions and also the conformally invariant two-point function. |
gr-qc/0005128 | Uzan | Jean-Philippe Uzan, Roland Lehoucq and Jean-Pierre Luminet | New Developments in the Search for the Topology of the Universe | 20 pages, 13 figures, Proceedings of the XIXth Texas meeting, Paris
14-18 december 1998, Proceedings of the XIXth Texas meeting, Eds. E. Aubourg,
T. Montmerle, J. Paul and P. Peter, article-no: 04/25 | null | null | null | gr-qc | null | Multi-connected Universe models with space idenfication scales smaller than
the size of the observable universe produce topological images in the catalogs
of cosmic sources. In this review, we present the recent developments for the
search of the topology of the universe focusing on three dimensional methods.
We present the crystallographic method, we give a new lower bound on the size
of locally Euclidean multi-connected universe model of $3000 h^{-1} \hbox{Mpc}$
based on this method and a quasar catalog, we discuss its successes and
failures, and the attemps to generalise it. We finally introduce a new
statistical method based on a collecting correlated pair (CCP) technique.
| [
{
"created": "Tue, 30 May 2000 08:28:05 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Uzan",
"Jean-Philippe",
""
],
[
"Lehoucq",
"Roland",
""
],
[
"Luminet",
"Jean-Pierre",
""
]
] | Multi-connected Universe models with space idenfication scales smaller than the size of the observable universe produce topological images in the catalogs of cosmic sources. In this review, we present the recent developments for the search of the topology of the universe focusing on three dimensional methods. We present the crystallographic method, we give a new lower bound on the size of locally Euclidean multi-connected universe model of $3000 h^{-1} \hbox{Mpc}$ based on this method and a quasar catalog, we discuss its successes and failures, and the attemps to generalise it. We finally introduce a new statistical method based on a collecting correlated pair (CCP) technique. |
0909.4676 | Otto Kong | Otto C. W. Kong and Hung-Yi Lee (Nat'l Central U., Taiwan) | Poincare-Snyder Relativity with Quantization | 17 pages in revtex, no figure | null | null | NCU-HEP-k036 | gr-qc math-ph math.MP quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on a linear realization formulation of a quantum relativity -- the
proposed relativity for quantum `space-time', we introduce the
Poincar\'e-Snyder relativity and Snyder relativity as relativities in between
the latter and the well known Galilean and Einstein cases. We discuss how the
Poincar\'e-Snyder relativity may provide a stronger framework for the
description of the usual (Einstein) relativistic quantum mechanics and beyond.
In particular, we discuss a geometric quantization picture through the U(1)
central extension of the relativity group, which had been establish to work
well for the Galilean case but not for the Einstein case. We discuss
similarities and differences between our Poincar\'e-Snyder picture with a still
not fully understood $\sigma$ variable as the `evolution' parameter and some
use of an invariant time or the proper time parameter in some earlier
formulations with very similar mathematical structure. The study is a first
step towards the investigation of physics of the $\sigma$ variable at the
Poincar\'e-Snyder setting, plausible leading to experimental signatures to be
studied.
| [
{
"created": "Fri, 25 Sep 2009 12:19:37 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Oct 2010 08:12:48 GMT",
"version": "v2"
}
] | 2010-10-19 | [
[
"Kong",
"Otto C. W.",
"",
"Nat'l Central U., Taiwan"
],
[
"Lee",
"Hung-Yi",
"",
"Nat'l Central U., Taiwan"
]
] | Based on a linear realization formulation of a quantum relativity -- the proposed relativity for quantum `space-time', we introduce the Poincar\'e-Snyder relativity and Snyder relativity as relativities in between the latter and the well known Galilean and Einstein cases. We discuss how the Poincar\'e-Snyder relativity may provide a stronger framework for the description of the usual (Einstein) relativistic quantum mechanics and beyond. In particular, we discuss a geometric quantization picture through the U(1) central extension of the relativity group, which had been establish to work well for the Galilean case but not for the Einstein case. We discuss similarities and differences between our Poincar\'e-Snyder picture with a still not fully understood $\sigma$ variable as the `evolution' parameter and some use of an invariant time or the proper time parameter in some earlier formulations with very similar mathematical structure. The study is a first step towards the investigation of physics of the $\sigma$ variable at the Poincar\'e-Snyder setting, plausible leading to experimental signatures to be studied. |
1310.6420 | Victor Varela | Victor Varela | A note on linearized stability of Schwarzschild thin-shell wormholes
with variable equations of state | Fifth version. 15 pages. Almost completely rewritten. Extended
analysis. New references | Phys. Rev. D 92, 044002 (2015) | 10.1103/PhysRevD.92.044002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss how the assumption of variable equation of state (EoS) allows the
elimination of the instability at equilibrium throat radius $a_0=3M$ featured
by previous Schwarzschild thin-shell wormhole models. Unobstructed stability
regions are found for three choices of variable EoS. Two of these EoS entail
linear stability at every equilibrium radius. Particularly, the thin-shell
remains stable as $a_0$ approaches the Schwarzschild radius $2M$. A
perturbative analysis of the wormhole equation of motion is carried out in the
case of variable Chaplygin EoS. The squared proper angular frequency
$\omega_0^2$ of small throat oscillations is linked with the second derivative
of the thin-shell potential. In various situations $\omega_0^2$ remains
positive and bounded in the limit $a_0\rightarrow 2M$.
| [
{
"created": "Wed, 23 Oct 2013 22:36:36 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Dec 2013 12:39:08 GMT",
"version": "v2"
},
{
"created": "Tue, 24 Dec 2013 18:54:31 GMT",
"version": "v3"
},
{
"created": "Thu, 6 Feb 2014 23:55:03 GMT",
"version": "v4"
},
{
"cr... | 2015-08-19 | [
[
"Varela",
"Victor",
""
]
] | We discuss how the assumption of variable equation of state (EoS) allows the elimination of the instability at equilibrium throat radius $a_0=3M$ featured by previous Schwarzschild thin-shell wormhole models. Unobstructed stability regions are found for three choices of variable EoS. Two of these EoS entail linear stability at every equilibrium radius. Particularly, the thin-shell remains stable as $a_0$ approaches the Schwarzschild radius $2M$. A perturbative analysis of the wormhole equation of motion is carried out in the case of variable Chaplygin EoS. The squared proper angular frequency $\omega_0^2$ of small throat oscillations is linked with the second derivative of the thin-shell potential. In various situations $\omega_0^2$ remains positive and bounded in the limit $a_0\rightarrow 2M$. |
1909.01827 | Fay\c{c}al Hammad | Alexandre Landry and Fay\c{c}al Hammad | Landau levels in a gravitational field: The Schwarzschild spacetime case | 37 pages, no figures, matches the published version | Universe 7(5), 144 (2021) | 10.3390/universe7050144 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the gravitational effect on Landau levels. We show that the
familiar infinite Landau degeneracy of the energy levels of a quantum particle
moving inside a uniform and constant magnetic field is removed by the
interaction of the particle with a gravitational field. Two independent
approaches are used to solve the relevant Schr\"odinger equation within the
Newtonian approximation. It is found that both approaches yield qualitatively
similar results within their respective approximations. With the goal of
clarifying some results found in the literature concerning the use of a third
independent approach for extracting the quantization condition based on a
similar differential equation, we show that such an approach cannot yield a
general and yet consistent result. We point out to the more accurate, but
impractical, way to use such an approach; a way which does in principle yield a
consistent quantization condition. We discuss how our results could be used to
contribute in a novel way to the existing methods for testing gravity at the
tabletop experiments level as well as at the astrophysical observational level
by deriving the corrections brought by Yukawa-like and power-law deviations
from the inverse-square law. The full relativistic regime is also examined in
detail.
| [
{
"created": "Mon, 2 Sep 2019 22:48:50 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Oct 2020 12:13:19 GMT",
"version": "v2"
},
{
"created": "Tue, 18 May 2021 17:43:44 GMT",
"version": "v3"
}
] | 2021-05-19 | [
[
"Landry",
"Alexandre",
""
],
[
"Hammad",
"Fayçal",
""
]
] | We investigate the gravitational effect on Landau levels. We show that the familiar infinite Landau degeneracy of the energy levels of a quantum particle moving inside a uniform and constant magnetic field is removed by the interaction of the particle with a gravitational field. Two independent approaches are used to solve the relevant Schr\"odinger equation within the Newtonian approximation. It is found that both approaches yield qualitatively similar results within their respective approximations. With the goal of clarifying some results found in the literature concerning the use of a third independent approach for extracting the quantization condition based on a similar differential equation, we show that such an approach cannot yield a general and yet consistent result. We point out to the more accurate, but impractical, way to use such an approach; a way which does in principle yield a consistent quantization condition. We discuss how our results could be used to contribute in a novel way to the existing methods for testing gravity at the tabletop experiments level as well as at the astrophysical observational level by deriving the corrections brought by Yukawa-like and power-law deviations from the inverse-square law. The full relativistic regime is also examined in detail. |
0706.3096 | Wuming Yang | W. M. Yang and S. L. Bi | The frequency separations of stellar p-modes | Accepted for Publication in A&A, 8 pages, 5 figures | A&A 472, 571-576 (2007) | 10.1051/0004-6361:20077082 | null | gr-qc | null | Aims. The purpose of this work is to investigate a new frequency separation
of stellar p-modes and its characteristics. Methods. Frequency separations are
deduced from the asymptotic formula of stellar p-modes. Then, using the
theoretical adiabatic frequencies of stellar model, we compute the frequency
separations. Results. A new separation $\sigma_{l-1 l+1}(n)$, which is similar
to the scaled small separation $d_{l l+2}(n)/(2l+3)$, is obtained from the
asymptotic formula of stellar p-modes. The separations $\sigma_{l-1 l+1}(n)$
and $d_{l l+2}(n)/(2l+3)$ have the same order. And like the small separation,
$\sigma_{l-1 l+1}(n)$ is mainly sensitive to the conditions in the stellar
core. However, with the decrease of the central hydrogen abundance of stars,
the $\sigma_{02}$ and $\sigma_{13}$ more and more deviate from the scaled small
separation. This characteristic could be used to extract the information on the
central hydrogen abundance of stars.
| [
{
"created": "Thu, 21 Jun 2007 08:06:18 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Sep 2007 16:13:38 GMT",
"version": "v2"
}
] | 2007-09-03 | [
[
"Yang",
"W. M.",
""
],
[
"Bi",
"S. L.",
""
]
] | Aims. The purpose of this work is to investigate a new frequency separation of stellar p-modes and its characteristics. Methods. Frequency separations are deduced from the asymptotic formula of stellar p-modes. Then, using the theoretical adiabatic frequencies of stellar model, we compute the frequency separations. Results. A new separation $\sigma_{l-1 l+1}(n)$, which is similar to the scaled small separation $d_{l l+2}(n)/(2l+3)$, is obtained from the asymptotic formula of stellar p-modes. The separations $\sigma_{l-1 l+1}(n)$ and $d_{l l+2}(n)/(2l+3)$ have the same order. And like the small separation, $\sigma_{l-1 l+1}(n)$ is mainly sensitive to the conditions in the stellar core. However, with the decrease of the central hydrogen abundance of stars, the $\sigma_{02}$ and $\sigma_{13}$ more and more deviate from the scaled small separation. This characteristic could be used to extract the information on the central hydrogen abundance of stars. |
2210.10103 | Alejandro Corichi | Alejandro Corichi and Dario N\'u\~nez | Introduction to the ADM formalism | 23 pages, 3 figures. Published in 1991, in Spanish. Translated into
English by Ribhu Paul. V2 has corrected typos. The authors have made no
effort to update it nor its bibliography. We hope, however, that by making it
publicly available it may be useful for students interested in learning the
3+1 formalism of general relativity within the ADM formalism | Rev. Mex. Fis. 37, No 4, 720-747 (1991) | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The authors present concepts and mathematical developments which give rise to
the Hamiltonian formulation of Einstein's general relativity, first introduced
by Arnowitt, Deser, and Misner. All the geometrical quantities needed for the
construction are explicitly obtained, and examples of some of the application
of the formalism are given.
| [
{
"created": "Tue, 18 Oct 2022 19:00:13 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Aug 2023 17:35:30 GMT",
"version": "v2"
}
] | 2023-08-23 | [
[
"Corichi",
"Alejandro",
""
],
[
"Núñez",
"Dario",
""
]
] | The authors present concepts and mathematical developments which give rise to the Hamiltonian formulation of Einstein's general relativity, first introduced by Arnowitt, Deser, and Misner. All the geometrical quantities needed for the construction are explicitly obtained, and examples of some of the application of the formalism are given. |
2304.09847 | Grigory Volovik | G.E. Volovik | On the global temperature of the Schwarzschild-de Sitter spacetime | 5 pages, no figures, continuation of the paper G.E. Volovik, Ann.
Phys. 449, 169219 (2023), version accepted in JETP Letters | null | 10.1134/S0021364023601173 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that the Schwarzschild-de Sitter (SdS) spacetime has the
fundamental temperature. This temperature describes the thermal processes of
decay of the composite particles and the other processes, which are
energetically forbidden in the Minkowski spacetime, but are allowed in the de
Sitter and in SdS backgrounds. In particular, this temperature describes the
probability of ionization of the atom in the SdS, which is observed by the
stationary observer at the point where the shift function (velocity) in the
Arnowitt-Deser-Misner formalism changes sign. This activation temperature does
not depend on the black hole mass and is fully determined by the Hubble
parameter, $T_{\rm SdS}=\sqrt{3}H/\pi$. This temperature is twice the
Bousso-Hawking temperature $T_{\rm BH}$, which characterizes the limit of
degenerate Lorentzian Schwarzschild-de Sitter universe, when the cosmological
and black hole horizons are close to each other, $T_{\rm SdS}=2T_{\rm BH}$.
The similar doubling of the temperature of Hawking radiation is known in the
pure de Sitter spacetime, where the corresponding local temperature describing
the ionization of atoms is twice the Gibbons-Hawking temperature, $T_{\rm
dS}=2T_{\rm GH}=H/\pi$. We suggest that the activation temperature $T_{\rm dS}$
can be considered as the thermodynamic temperature of the de Sitter state,
which determines the local entropy in this state, $s=3H/4G$.
| [
{
"created": "Tue, 18 Apr 2023 13:20:02 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Apr 2023 14:25:38 GMT",
"version": "v2"
},
{
"created": "Tue, 25 Apr 2023 15:25:16 GMT",
"version": "v3"
},
{
"created": "Fri, 28 Apr 2023 12:03:00 GMT",
"version": "v4"
},
{
"c... | 2023-07-12 | [
[
"Volovik",
"G. E.",
""
]
] | It is shown that the Schwarzschild-de Sitter (SdS) spacetime has the fundamental temperature. This temperature describes the thermal processes of decay of the composite particles and the other processes, which are energetically forbidden in the Minkowski spacetime, but are allowed in the de Sitter and in SdS backgrounds. In particular, this temperature describes the probability of ionization of the atom in the SdS, which is observed by the stationary observer at the point where the shift function (velocity) in the Arnowitt-Deser-Misner formalism changes sign. This activation temperature does not depend on the black hole mass and is fully determined by the Hubble parameter, $T_{\rm SdS}=\sqrt{3}H/\pi$. This temperature is twice the Bousso-Hawking temperature $T_{\rm BH}$, which characterizes the limit of degenerate Lorentzian Schwarzschild-de Sitter universe, when the cosmological and black hole horizons are close to each other, $T_{\rm SdS}=2T_{\rm BH}$. The similar doubling of the temperature of Hawking radiation is known in the pure de Sitter spacetime, where the corresponding local temperature describing the ionization of atoms is twice the Gibbons-Hawking temperature, $T_{\rm dS}=2T_{\rm GH}=H/\pi$. We suggest that the activation temperature $T_{\rm dS}$ can be considered as the thermodynamic temperature of the de Sitter state, which determines the local entropy in this state, $s=3H/4G$. |
0905.1355 | Francisco Lobo | Tiberiu Harko, Zolt\'an Kov\'acs, Francisco S. N. Lobo | Can accretion disk properties distinguish gravastars from black holes? | 12 pages, 12 figures. V2: 14 pages, significant discussion and
references added, to appear in Class.Quant.Grav | Class.Quant.Grav.26:215006,2009 | 10.1088/0264-9381/26/21/215006 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravastars, hypothetic astrophysical objects, consisting of a dark energy
condensate surrounded by a strongly correlated thin shell of anisotropic
matter, have been proposed as an alternative to the standard black hole picture
of general relativity. Observationally distinguishing between astrophysical
black holes and gravastars is a major challenge for this latter theoretical
model. In the context of stationary and axially symmetrical geometries, a
possibility of distinguishing gravastars from black holes is through the
comparative study of thin accretion disks around rotating gravastars and
Kerr-type black holes, respectively. In the present paper, we consider
accretion disks around slowly rotating gravastars, with all the metric tensor
components estimated up to the second order in the angular velocity. Due to the
differences in the exterior geometry, the thermodynamic and electromagnetic
properties of the disks (energy flux, temperature distribution and equilibrium
radiation spectrum) are different for these two classes of compact objects,
consequently giving clear observational signatures. In addition to this, it is
also shown that the conversion efficiency of the accreting mass into radiation
is always smaller than the conversion efficiency for black holes, i.e.,
gravastars provide a less efficient mechanism for converting mass to radiation
than black holes. Thus, these observational signatures provide the possibility
of clearly distinguishing rotating gravastars from Kerr-type black holes.
| [
{
"created": "Fri, 8 May 2009 22:16:20 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Sep 2009 20:52:42 GMT",
"version": "v2"
}
] | 2009-10-06 | [
[
"Harko",
"Tiberiu",
""
],
[
"Kovács",
"Zoltán",
""
],
[
"Lobo",
"Francisco S. N.",
""
]
] | Gravastars, hypothetic astrophysical objects, consisting of a dark energy condensate surrounded by a strongly correlated thin shell of anisotropic matter, have been proposed as an alternative to the standard black hole picture of general relativity. Observationally distinguishing between astrophysical black holes and gravastars is a major challenge for this latter theoretical model. In the context of stationary and axially symmetrical geometries, a possibility of distinguishing gravastars from black holes is through the comparative study of thin accretion disks around rotating gravastars and Kerr-type black holes, respectively. In the present paper, we consider accretion disks around slowly rotating gravastars, with all the metric tensor components estimated up to the second order in the angular velocity. Due to the differences in the exterior geometry, the thermodynamic and electromagnetic properties of the disks (energy flux, temperature distribution and equilibrium radiation spectrum) are different for these two classes of compact objects, consequently giving clear observational signatures. In addition to this, it is also shown that the conversion efficiency of the accreting mass into radiation is always smaller than the conversion efficiency for black holes, i.e., gravastars provide a less efficient mechanism for converting mass to radiation than black holes. Thus, these observational signatures provide the possibility of clearly distinguishing rotating gravastars from Kerr-type black holes. |
2301.08331 | Suvrat Rao | Suvrat Rao, Julia Baumgarten, Jochen Liske and Marcus Br\"uggen | Detection of gravitational waves in circular particle accelerators II.
Response analysis and parameter estimation using synthetic data | This manuscript is the updated version of arXiv:2301.08331v2, and has
been accepted for publication as a Regular Article in Physical Review D
(PRD). 25 pages, 11 figures | null | null | null | gr-qc astro-ph.IM hep-ph physics.acc-ph physics.ins-det | http://creativecommons.org/licenses/by/4.0/ | We simulate the response of a Storage Ring Gravitational-Wave Observatory
(SRGO) to astrophysical millihertz (mHz) gravitational waves (GWs), numerically
obtaining its sensitivity curve and optimal choices for some controllable
experiment parameters. We also generate synthetic noisy GW data and use Markov
Chain Monte Carlo (MCMC) methods to perform parameter estimation of the source
properties and their degeneracies. We show that a single SRGO could potentially
localize the GW source in the sky using Earth's rotation. We also study the
source sky localization area, mass and distance estimation errors as functions
of noise, data sampling rate, and observing time. Finally, we discuss, along
with its implications, the capacity of an SRGO to detect and constrain the
parameters of millihertz GW events.
| [
{
"created": "Wed, 18 Jan 2023 05:41:36 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Jan 2024 16:21:11 GMT",
"version": "v2"
},
{
"created": "Tue, 11 Jun 2024 22:00:56 GMT",
"version": "v3"
}
] | 2024-06-13 | [
[
"Rao",
"Suvrat",
""
],
[
"Baumgarten",
"Julia",
""
],
[
"Liske",
"Jochen",
""
],
[
"Brüggen",
"Marcus",
""
]
] | We simulate the response of a Storage Ring Gravitational-Wave Observatory (SRGO) to astrophysical millihertz (mHz) gravitational waves (GWs), numerically obtaining its sensitivity curve and optimal choices for some controllable experiment parameters. We also generate synthetic noisy GW data and use Markov Chain Monte Carlo (MCMC) methods to perform parameter estimation of the source properties and their degeneracies. We show that a single SRGO could potentially localize the GW source in the sky using Earth's rotation. We also study the source sky localization area, mass and distance estimation errors as functions of noise, data sampling rate, and observing time. Finally, we discuss, along with its implications, the capacity of an SRGO to detect and constrain the parameters of millihertz GW events. |
1905.07229 | Gamal G.L. Nashed | G.G.L. Nashed and Kazuharu Bamba | Charged (A)dS black hole solutions in conformal teleparallel equivalent
of general relativity | 12 pages | Phys. Rev. D 101, 044029 (2020) | 10.1103/PhysRevD.101.044029 | FU-PCG-65 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We continue our study in 4-dimension to derive non-charged and charged
(Anti)-de Sitter black hole solutions in conformal teleparallel equivalent of
general relativity. The non-charged and charged equations of motion are applied
to a spherically symmetric tetrad and the non-linear differential equations are
derived. It is shown that the output solutions of the two cases are identical
to those obtained in teleparallel equivalent theory to general relativity. As a
result, it is found that in the conformal teleparallel equivalent theory to
general relativity, the scalar field cannot influence on the manifold of
spherical symmetry, i.e. the scalar field must equal 1 in order to have a well
known asymptote spacetime.
| [
{
"created": "Tue, 14 May 2019 15:02:05 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Aug 2019 15:27:20 GMT",
"version": "v2"
},
{
"created": "Tue, 28 Jan 2020 08:37:28 GMT",
"version": "v3"
},
{
"created": "Wed, 25 Mar 2020 10:07:54 GMT",
"version": "v4"
}
] | 2020-03-26 | [
[
"Nashed",
"G. G. L.",
""
],
[
"Bamba",
"Kazuharu",
""
]
] | We continue our study in 4-dimension to derive non-charged and charged (Anti)-de Sitter black hole solutions in conformal teleparallel equivalent of general relativity. The non-charged and charged equations of motion are applied to a spherically symmetric tetrad and the non-linear differential equations are derived. It is shown that the output solutions of the two cases are identical to those obtained in teleparallel equivalent theory to general relativity. As a result, it is found that in the conformal teleparallel equivalent theory to general relativity, the scalar field cannot influence on the manifold of spherical symmetry, i.e. the scalar field must equal 1 in order to have a well known asymptote spacetime. |
1406.6600 | Aur\'elien Hees | A. Hees, S. Bertone, C. Le Poncin-Lafitte | Light propagation in the field of a moving axisymmetric body: theory and
application to JUNO | 17 pages, 4 figures, submitted to Phys. Rev. D, some corrections
after review | Phys. Rev. D 90, 084020, 2014 | 10.1103/PhysRevD.90.084020 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Given the extreme accuracy of modern space science, a precise relativistic
modeling of observations is required. We use the Time Transfer Functions
formalism to study light propagation in the field of uniformly moving
axisymmetric bodies, which extends the field of application of previous works.
We first present a space-time metric adapted to describe the geometry of an
ensemble of uniformly moving bodies. Then, we show that the expression of the
Time Transfer Functions in the field of a uniformly moving body can be easily
derived from its well-known expression in a stationary field by using a change
of variables. We also give a general expression of the Time Transfer Function
in the case of an ensemble of arbitrarily moving point masses. This result is
given in the form of an integral easily computable numerically. We also provide
the derivatives of the Time Transfer Function in this case, which are mandatory
to compute Doppler and astrometric observables. We particularize our results in
the case of moving axisymmetric bodies. Finally, we apply our results to study
the different relativistic contributions to the range and Doppler tracking for
the JUNO mission in the Jovian system.
| [
{
"created": "Wed, 25 Jun 2014 15:01:23 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Sep 2014 16:53:07 GMT",
"version": "v2"
}
] | 2014-10-15 | [
[
"Hees",
"A.",
""
],
[
"Bertone",
"S.",
""
],
[
"Poncin-Lafitte",
"C. Le",
""
]
] | Given the extreme accuracy of modern space science, a precise relativistic modeling of observations is required. We use the Time Transfer Functions formalism to study light propagation in the field of uniformly moving axisymmetric bodies, which extends the field of application of previous works. We first present a space-time metric adapted to describe the geometry of an ensemble of uniformly moving bodies. Then, we show that the expression of the Time Transfer Functions in the field of a uniformly moving body can be easily derived from its well-known expression in a stationary field by using a change of variables. We also give a general expression of the Time Transfer Function in the case of an ensemble of arbitrarily moving point masses. This result is given in the form of an integral easily computable numerically. We also provide the derivatives of the Time Transfer Function in this case, which are mandatory to compute Doppler and astrometric observables. We particularize our results in the case of moving axisymmetric bodies. Finally, we apply our results to study the different relativistic contributions to the range and Doppler tracking for the JUNO mission in the Jovian system. |
1103.0075 | Hamid Reza Sepangi | Z. Haghani, H. R. Sepangi and S. Shahidi | Anisotropy in Born-Infeld brane cosmology | 7 pages, 3 figures, to appear in PRD | Phys.Rev.D83:064014,2011 | 10.1103/PhysRevD.83.064014 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The accelerated expansion of the universe together with its present day
isotropy has posed an interesting challenge to the numerous model theories
presented over the years to describe them. In this paper, we address the above
questions in the context of a brane-world model where the universe is filled
with a Born-Infeld matter. We show that in such a model, the universe evolves
from a highly anisotropic state to its present isotropic form which has entered
an accelerated expanding phase.
| [
{
"created": "Tue, 1 Mar 2011 04:14:07 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Apr 2011 06:59:08 GMT",
"version": "v2"
}
] | 2011-04-04 | [
[
"Haghani",
"Z.",
""
],
[
"Sepangi",
"H. R.",
""
],
[
"Shahidi",
"S.",
""
]
] | The accelerated expansion of the universe together with its present day isotropy has posed an interesting challenge to the numerous model theories presented over the years to describe them. In this paper, we address the above questions in the context of a brane-world model where the universe is filled with a Born-Infeld matter. We show that in such a model, the universe evolves from a highly anisotropic state to its present isotropic form which has entered an accelerated expanding phase. |
gr-qc/0004077 | Rainer E. Zimmermann | Rainer E. Zimmermann | Loops and Knots as Topoi of Substance. Spinoza Revisited | 42 pages | null | null | null | gr-qc | null | The relationship between modern philosophy and physics is discussed. It is
shown that the latter develops some need for a modernized metaphysics which
shows up as an ultima philosophia of considerable heuristic value, rather than
as the prima philosophia in the Aristotelian sense as it had been intended, in
the first place. It is shown then, that it is the philosophy of Spinoza in
fact, that can still serve as a paradigm for such an approach. In particular,
Spinoza's concept of infinite substance is compared with the philosophical
implications of the foundational aspects of modern physical theory. Various
connotations of sub-stance are discussed within pre-geometric theories,
especially with a view to the role of spin networks within quantum gravity. It
is found to be useful to intro-duce a separation into physics then, so as to
differ between foundational and empirical theories, respectively. This leads to
a straightforward connection bet-ween foundational theories and speculative
philosophy on the one hand, and between empirical theories and sceptical
philosophy on the other. This might help in the end, to clarify some recent
problems, such as the absence of time and causality at a fundamental level. It
is implied that recent results relating to topos theory might open the way
towards eventually deriving logic from physics, and also towards a possible
transition from logic to hermeneutic.
| [
{
"created": "Thu, 27 Apr 2000 11:06:22 GMT",
"version": "v1"
},
{
"created": "Tue, 23 May 2000 09:20:13 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Zimmermann",
"Rainer E.",
""
]
] | The relationship between modern philosophy and physics is discussed. It is shown that the latter develops some need for a modernized metaphysics which shows up as an ultima philosophia of considerable heuristic value, rather than as the prima philosophia in the Aristotelian sense as it had been intended, in the first place. It is shown then, that it is the philosophy of Spinoza in fact, that can still serve as a paradigm for such an approach. In particular, Spinoza's concept of infinite substance is compared with the philosophical implications of the foundational aspects of modern physical theory. Various connotations of sub-stance are discussed within pre-geometric theories, especially with a view to the role of spin networks within quantum gravity. It is found to be useful to intro-duce a separation into physics then, so as to differ between foundational and empirical theories, respectively. This leads to a straightforward connection bet-ween foundational theories and speculative philosophy on the one hand, and between empirical theories and sceptical philosophy on the other. This might help in the end, to clarify some recent problems, such as the absence of time and causality at a fundamental level. It is implied that recent results relating to topos theory might open the way towards eventually deriving logic from physics, and also towards a possible transition from logic to hermeneutic. |
gr-qc/0602060 | E. M. Monte | E. M. Monte | Geometric Constraint in Brane-World | 4 pages. Proceedings of 10th Marcel Grossmann Meeting on Recent
Developments in Theoretical and Experimental General Relativity, Gravitation
and Relativistic Field Theories (MG X MMIII), Rio de Janeiro, Brazil, 20-26
Jul 2003 | null | null | null | gr-qc | null | The brane-worlds model was inspired partly by Kaluza-Klein's theory, where
the gravitation and the gauge fields are obtained of a geometry of higher
dimension (bulk). Such a model has been showing positive in the sense of we
find perspectives and probably deep modifications in the physics, such as:
Unification in a scale TeV, quantum gravity in this scale and deviation of
Newton's law for small distances. One of the principles of this model is to
suppose a space-time embedded in a bulk of high dimension. In this note it is
shown, basing on the theorem of Collinson-Szekeres, that the space-time of
Schwarzschild cannot be embedded locally and isometrically in a bulk of five
dimensions with constant curvature,(for example ADS-5). From the point of view
of the semi-Riemannian geometry this last result consists constraints to the
model brane-world.
| [
{
"created": "Wed, 15 Feb 2006 12:04:47 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Monte",
"E. M.",
""
]
] | The brane-worlds model was inspired partly by Kaluza-Klein's theory, where the gravitation and the gauge fields are obtained of a geometry of higher dimension (bulk). Such a model has been showing positive in the sense of we find perspectives and probably deep modifications in the physics, such as: Unification in a scale TeV, quantum gravity in this scale and deviation of Newton's law for small distances. One of the principles of this model is to suppose a space-time embedded in a bulk of high dimension. In this note it is shown, basing on the theorem of Collinson-Szekeres, that the space-time of Schwarzschild cannot be embedded locally and isometrically in a bulk of five dimensions with constant curvature,(for example ADS-5). From the point of view of the semi-Riemannian geometry this last result consists constraints to the model brane-world. |
gr-qc/0410058 | Beverly K. Berger | Beverly K. Berger | Why Solve the Hamiltonian Constraint in Numerical Relativity? | Submitted to a volume in honor of Michael P. Ryan, Jr. Based on talk
given at GR17 | Gen.Rel.Grav. 38 (2006) 625-632 | 10.1007/s10714-006-0252-y | null | gr-qc | null | The indefinite sign of the Hamiltonian constraint means that solutions to
Einstein's equations must achieve a delicate balance--often among numerically
large terms that nearly cancel. If numerical errors cause a violation of the
Hamiltonian constraint, the failure of the delicate balance could lead to
qualitatively wrong behavior rather than just decreased accuracy. This issue is
different from instabilities caused by constraint-violating modes. Examples of
stable numerical simulations of collapsing cosmological spacetimes exhibiting
local mixmaster dynamics with and without Hamiltonian constraint enforcement
are presented.
| [
{
"created": "Wed, 13 Oct 2004 21:40:48 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Berger",
"Beverly K.",
""
]
] | The indefinite sign of the Hamiltonian constraint means that solutions to Einstein's equations must achieve a delicate balance--often among numerically large terms that nearly cancel. If numerical errors cause a violation of the Hamiltonian constraint, the failure of the delicate balance could lead to qualitatively wrong behavior rather than just decreased accuracy. This issue is different from instabilities caused by constraint-violating modes. Examples of stable numerical simulations of collapsing cosmological spacetimes exhibiting local mixmaster dynamics with and without Hamiltonian constraint enforcement are presented. |
1502.05735 | Edward Porter | Edward K. Porter and Neil J. Cornish | Fisher vs. Bayes : A comparison of parameter estimation techniques for
massive black hole binaries to high redshifts with eLISA | 15 pages | null | 10.1103/PhysRevD.91.104001 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Massive black hole binaries are the primary source of gravitational waves
(GW) for the future eLISA observatory. The detection and parameter estimation
of these sources to high redshift would provide invaluable information on the
formation mechanisms of seed black holes, and on the evolution of massive black
holes and their host galaxies through cosmic time. The Fisher information
matrix has been the standard tool for GW parameter estimation in the last two
decades. However, recent studies have questioned the validity of using the
Fisher matrix approach. For example, the Fisher matrix approach sometimes
predicts errors of $\geq100\%$ in the estimation of parameters such as the
luminosity distance and sky position. With advances in computing power,
Bayesian inference is beginning to replace the Fisher matrix approximation in
parameter estimation studies. In this work, we conduct a Bayesian inference
analysis for 120 sources situated at redshifts of between $0.1\leq z\leq 13.2$,
and compare the results with those from a Fisher matrix analysis. The Fisher
matrix results suggest that for this particular selection of sources, eLISA
would be unable to localize sources at redshifts of $z\lesssim6$. In contrast,
Bayesian inference provides finite error estimations for all sources in the
study, and shows that we can establish minimum closest distances for all
sources. The study further predicts that we should be capable with eLISA, out
to a redshift of at least $z\leq13$, of predicting a maximum error in the chirp
mass of $\lesssim 1\%$, the reduced mass of $\lesssim20\%$, the time to
coalescence of 2 hours, and to a redshift of $z\sim5$, the inclination of the
source with a maximum error of $\sim60$ degrees.
| [
{
"created": "Thu, 19 Feb 2015 21:54:49 GMT",
"version": "v1"
}
] | 2015-05-27 | [
[
"Porter",
"Edward K.",
""
],
[
"Cornish",
"Neil J.",
""
]
] | Massive black hole binaries are the primary source of gravitational waves (GW) for the future eLISA observatory. The detection and parameter estimation of these sources to high redshift would provide invaluable information on the formation mechanisms of seed black holes, and on the evolution of massive black holes and their host galaxies through cosmic time. The Fisher information matrix has been the standard tool for GW parameter estimation in the last two decades. However, recent studies have questioned the validity of using the Fisher matrix approach. For example, the Fisher matrix approach sometimes predicts errors of $\geq100\%$ in the estimation of parameters such as the luminosity distance and sky position. With advances in computing power, Bayesian inference is beginning to replace the Fisher matrix approximation in parameter estimation studies. In this work, we conduct a Bayesian inference analysis for 120 sources situated at redshifts of between $0.1\leq z\leq 13.2$, and compare the results with those from a Fisher matrix analysis. The Fisher matrix results suggest that for this particular selection of sources, eLISA would be unable to localize sources at redshifts of $z\lesssim6$. In contrast, Bayesian inference provides finite error estimations for all sources in the study, and shows that we can establish minimum closest distances for all sources. The study further predicts that we should be capable with eLISA, out to a redshift of at least $z\leq13$, of predicting a maximum error in the chirp mass of $\lesssim 1\%$, the reduced mass of $\lesssim20\%$, the time to coalescence of 2 hours, and to a redshift of $z\sim5$, the inclination of the source with a maximum error of $\sim60$ degrees. |
1406.1591 | Soon-Tae Hong | Soon-Tae Hong | Interior properties of five-dimensional Schwarzschild black hole | 6 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate inner structure of Schwarzschild black hole on a
five-dimensional spacetime S^3xR^2. To do this, we exploit a f\"unfbein scheme.
In particular, we construct an equation of state of hydrostatic equilibrium for
the five-dimensional Schwarzschild black hole, which is a five-dimensional
version of the Tolman-Oppenheimer-Volkoff equation on four-dimensional
manifold. We also investigate uniform density interior configuration of the
five-dimensional black hole which consists of incompressible fluid of density,
to find a general relativistic expression for pressure.
| [
{
"created": "Fri, 6 Jun 2014 06:09:08 GMT",
"version": "v1"
}
] | 2014-06-09 | [
[
"Hong",
"Soon-Tae",
""
]
] | We investigate inner structure of Schwarzschild black hole on a five-dimensional spacetime S^3xR^2. To do this, we exploit a f\"unfbein scheme. In particular, we construct an equation of state of hydrostatic equilibrium for the five-dimensional Schwarzschild black hole, which is a five-dimensional version of the Tolman-Oppenheimer-Volkoff equation on four-dimensional manifold. We also investigate uniform density interior configuration of the five-dimensional black hole which consists of incompressible fluid of density, to find a general relativistic expression for pressure. |
1401.6976 | Graham Cox | Amir Babak Aazami, Graham Cox | Blowup solutions of Jang's equation near a spacetime singularity | 18 pages, 1 figure; second version has expanded Introduction, and new
description of blowup solutions in Section 4 | Class. Quantum Grav. 31 (2014) | 10.1088/0264-9381/31/11/115007 | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study Jang's equation on a one-parameter family of asymptotically flat,
spherically symmetric Cauchy hypersurfaces in the maximally extended
Schwarzschild spacetime. The hypersurfaces contain apparent horizons and are
parametrized by their proximity to the singularity at $r = 0$. We show that on
those hypersurfaces sufficiently close to the singularity, every radial
solution to Jang's equation blows up. The proof depends only on the geometry in
an arbitrarily small neighborhood of the singularity, suggesting that Jang's
equation is in fact detecting the singularity. We comment on possible
applications to the weak cosmic censorship conjecture.
| [
{
"created": "Mon, 27 Jan 2014 19:33:01 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Oct 2014 18:55:03 GMT",
"version": "v2"
}
] | 2014-10-17 | [
[
"Aazami",
"Amir Babak",
""
],
[
"Cox",
"Graham",
""
]
] | We study Jang's equation on a one-parameter family of asymptotically flat, spherically symmetric Cauchy hypersurfaces in the maximally extended Schwarzschild spacetime. The hypersurfaces contain apparent horizons and are parametrized by their proximity to the singularity at $r = 0$. We show that on those hypersurfaces sufficiently close to the singularity, every radial solution to Jang's equation blows up. The proof depends only on the geometry in an arbitrarily small neighborhood of the singularity, suggesting that Jang's equation is in fact detecting the singularity. We comment on possible applications to the weak cosmic censorship conjecture. |
0906.4404 | Hamid Reza Sepangi | S. Jalalzadeh, M. Mehrnia and H. R. Sepangi | Classical tests in brane gravity | 10 pages, no figures, to appear in CQG | Class.Quant.Grav.26:155007,2009 | 10.1088/0264-9381/26/15/155007 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The vacuum solutions in brane gravity differ from those in 4D by a number of
additional terms and reduce to the familiar Schwarzschild metric at small
distances. We study the possible roles that such terms may play in the
precession of planetary orbits, bending of light, radar retardation and the
anomaly in mean motion of test bodies. Using the available data from Solar
System experiments, we determine the range of the free parameters associated
with the linear term in the metric. The best results come from the anomalies in
the mean motion of planets. Such studies should shed some light on the origin
of dark energy via the solar system tests.
| [
{
"created": "Wed, 24 Jun 2009 05:27:03 GMT",
"version": "v1"
}
] | 2009-09-15 | [
[
"Jalalzadeh",
"S.",
""
],
[
"Mehrnia",
"M.",
""
],
[
"Sepangi",
"H. R.",
""
]
] | The vacuum solutions in brane gravity differ from those in 4D by a number of additional terms and reduce to the familiar Schwarzschild metric at small distances. We study the possible roles that such terms may play in the precession of planetary orbits, bending of light, radar retardation and the anomaly in mean motion of test bodies. Using the available data from Solar System experiments, we determine the range of the free parameters associated with the linear term in the metric. The best results come from the anomalies in the mean motion of planets. Such studies should shed some light on the origin of dark energy via the solar system tests. |
2405.11840 | Mahnaz Asghari | Mahnaz Asghari and Ahmad Sheykhi | Growth of cosmic perturbations in the modified $f(R,T)$ gravity | 9 pages, 6 figures | null | null | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | We explore the generalized $f(R,T)$ modified theory of gravity, where the
gravitational Lagrangian is a function of Ricci scalar $R$ and the trace of the
energy-momentum tensor $T$. We derive modified field equations to the linear
order of perturbations in the context of $f(R,T)$ model. We then investigate
the growth of perturbations in the context of $f(R,T)$ modified gravity.
Primary numerical investigations based on matter power spectra diagrams
indicates a structure growth suppression in $f(R,T)$ gravity, which exhibits
consistency with local measurements. Also, we notice that matter-geometry
interaction in $f(R,T)$ model would results in the specific feature named as
"matter acoustic oscillations" appeared in matter power spectra diagrams.
Moreover, we put constraints on the cosmological parameters of $f(R,T)$ model,
utilizing current observations, chiefly cosmic microwave background, weak
lensing, supernovae, baryon acoustic oscillations, and redshift-space
distortions data. Numerical results based on MCMC calculations imply that
$f(R,T)$ is a qualified theory of modified gravity in reconciling Planck CMB
data with local probes of large scale structures, by reporting lower values for
the structure growth parameter $\sigma_8$ compared to the standard model of
cosmology.
| [
{
"created": "Mon, 20 May 2024 07:33:07 GMT",
"version": "v1"
},
{
"created": "Sat, 13 Jul 2024 15:00:20 GMT",
"version": "v2"
}
] | 2024-07-16 | [
[
"Asghari",
"Mahnaz",
""
],
[
"Sheykhi",
"Ahmad",
""
]
] | We explore the generalized $f(R,T)$ modified theory of gravity, where the gravitational Lagrangian is a function of Ricci scalar $R$ and the trace of the energy-momentum tensor $T$. We derive modified field equations to the linear order of perturbations in the context of $f(R,T)$ model. We then investigate the growth of perturbations in the context of $f(R,T)$ modified gravity. Primary numerical investigations based on matter power spectra diagrams indicates a structure growth suppression in $f(R,T)$ gravity, which exhibits consistency with local measurements. Also, we notice that matter-geometry interaction in $f(R,T)$ model would results in the specific feature named as "matter acoustic oscillations" appeared in matter power spectra diagrams. Moreover, we put constraints on the cosmological parameters of $f(R,T)$ model, utilizing current observations, chiefly cosmic microwave background, weak lensing, supernovae, baryon acoustic oscillations, and redshift-space distortions data. Numerical results based on MCMC calculations imply that $f(R,T)$ is a qualified theory of modified gravity in reconciling Planck CMB data with local probes of large scale structures, by reporting lower values for the structure growth parameter $\sigma_8$ compared to the standard model of cosmology. |
1106.1922 | Motoyuki Saijo | Motoyuki Saijo | Dynamic black holes through gravitational collapse: Analysis of
multipole moment of the curvatures on the horizon | 13 pages with 19 figures, revtex4-1.cls. Accepted for publication in
the Physical Review D | Phys.Rev.D83:124031,2011 | 10.1103/PhysRevD.83.124031 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have investigated several properties of rapidly rotating dynamic black
holes generated by gravitational collapse of rotating relativistic stars. At
present, numerical simulations of the binary black hole merger are able to
produce a Kerr black hole of J_final / M_final^2 up to = 0.91, of gravitational
collapse from uniformly rotating stars up to J_final / M_final^2 ~ 0.75, where
J_final is the total angular momentum and M_final the total gravitational mass
of the hole. We have succeeded in producing a dynamic black hole of spin
J_final / M_final^2 ~ 0.95 through the collapse of differentially rotating
relativistic stars. We have investigated those dynamic properties through
diagnosing multipole moment of the horizon, and found the following two
features. Firstly, two different definitions of the angular momentum of the
hole, the approximated Killing vector approach and dipole moment of the current
multipole approach, make no significant difference to our computational
results. Secondly, dynamic hole approaches a Kerr by gravitational radiation
within the order of a rotational period of an equilibrium star, although the
dynamic hole at the very forming stage deviates quite far from a Kerr. We have
also discussed a new phase of quasi-periodic waves in the gravitational
waveform after the ringdown in terms of multipole moment of the dynamic hole.
| [
{
"created": "Thu, 9 Jun 2011 21:47:44 GMT",
"version": "v1"
}
] | 2011-06-23 | [
[
"Saijo",
"Motoyuki",
""
]
] | We have investigated several properties of rapidly rotating dynamic black holes generated by gravitational collapse of rotating relativistic stars. At present, numerical simulations of the binary black hole merger are able to produce a Kerr black hole of J_final / M_final^2 up to = 0.91, of gravitational collapse from uniformly rotating stars up to J_final / M_final^2 ~ 0.75, where J_final is the total angular momentum and M_final the total gravitational mass of the hole. We have succeeded in producing a dynamic black hole of spin J_final / M_final^2 ~ 0.95 through the collapse of differentially rotating relativistic stars. We have investigated those dynamic properties through diagnosing multipole moment of the horizon, and found the following two features. Firstly, two different definitions of the angular momentum of the hole, the approximated Killing vector approach and dipole moment of the current multipole approach, make no significant difference to our computational results. Secondly, dynamic hole approaches a Kerr by gravitational radiation within the order of a rotational period of an equilibrium star, although the dynamic hole at the very forming stage deviates quite far from a Kerr. We have also discussed a new phase of quasi-periodic waves in the gravitational waveform after the ringdown in terms of multipole moment of the dynamic hole. |
1703.00193 | Jamir Marino Dr | Gabriel Menezes, Claus Kiefer, Jamir Marino | Thermal and nonthermal scaling of the Casimir-Polder interaction in a
black hole spacetime | 16 pages, 1 figure | Phys. Rev. D 95, 085014 (2017) | 10.1103/PhysRevD.95.085014 | null | gr-qc cond-mat.other quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the Casimir-Polder force arising between two identical two-level
atoms and mediated by a massless scalar field propagating in a black-hole
background. We study the interplay of Hawking radiation and Casimir-Polder
forces and find that, when the atoms are placed near the event horizon, the
scaling of the Casimir-Polder interaction energy as a function of interatomic
distance displays a transition from a thermallike character to a nonthermal
behavior. We corroborate our findings for a quantum field prepared in the
Boulware, Hartle-Hawking, and Unruh vacua. Our analysis is consistent with the
nonthermal character of the Casimir-Polder interaction of two-level atoms in a
relativistic accelerated frame [J. Marino et al., Phys. Rev. Lett. 113, 020403
(2014)], where a crossover from thermal scaling, consistent with the Unruh
effect, to a nonthermal scaling has been observed. The two crossovers are a
consequence of the noninertial character of the background where the field
mediating the Casimir interaction propagates. While in the former case the
characteristic crossover length scale is proportional to the inverse of the
surface gravity of the black hole, in the latter it is determined by the
inverse of the proper acceleration of the atoms.
| [
{
"created": "Wed, 1 Mar 2017 09:31:38 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Apr 2017 07:12:51 GMT",
"version": "v2"
}
] | 2017-04-21 | [
[
"Menezes",
"Gabriel",
""
],
[
"Kiefer",
"Claus",
""
],
[
"Marino",
"Jamir",
""
]
] | We study the Casimir-Polder force arising between two identical two-level atoms and mediated by a massless scalar field propagating in a black-hole background. We study the interplay of Hawking radiation and Casimir-Polder forces and find that, when the atoms are placed near the event horizon, the scaling of the Casimir-Polder interaction energy as a function of interatomic distance displays a transition from a thermallike character to a nonthermal behavior. We corroborate our findings for a quantum field prepared in the Boulware, Hartle-Hawking, and Unruh vacua. Our analysis is consistent with the nonthermal character of the Casimir-Polder interaction of two-level atoms in a relativistic accelerated frame [J. Marino et al., Phys. Rev. Lett. 113, 020403 (2014)], where a crossover from thermal scaling, consistent with the Unruh effect, to a nonthermal scaling has been observed. The two crossovers are a consequence of the noninertial character of the background where the field mediating the Casimir interaction propagates. While in the former case the characteristic crossover length scale is proportional to the inverse of the surface gravity of the black hole, in the latter it is determined by the inverse of the proper acceleration of the atoms. |
2402.07828 | F Shojai | A. Sadeghi, F. Shojai and F. Bahmani | Surface gravity in spherically symmetric collapsing stars | 13 pages, 2 figures, accepted for publication in EPJC | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Here we consider the generalized Oppenheimer-Snyder collapse of a star into a
four-dimensional Einstein-Gauss-Bonnet black hole as well as a class of regular
black holes labeled by the polytropic index of the stellar matter. We then
analyze the nature of the horizon and the corresponding surface gravity outside
and inside the star. The Hayward and Nielsen-Visser dynamical surface gravity
are in agreement with the one resulting from the Killing vector of the outer
static metric. However, these two definitions inside the star do not coincide
with the Killing surface gravity outside the star when the star crosses the
event horizon. This motivates us to study the surface gravity using Fodor's
approach to have a unique surface gravity at the mentioned moment. Then the
extremality condition and the first law of thermodynamics are discussed at the
trapping horizon of the star.
| [
{
"created": "Mon, 12 Feb 2024 17:34:17 GMT",
"version": "v1"
}
] | 2024-02-13 | [
[
"Sadeghi",
"A.",
""
],
[
"Shojai",
"F.",
""
],
[
"Bahmani",
"F.",
""
]
] | Here we consider the generalized Oppenheimer-Snyder collapse of a star into a four-dimensional Einstein-Gauss-Bonnet black hole as well as a class of regular black holes labeled by the polytropic index of the stellar matter. We then analyze the nature of the horizon and the corresponding surface gravity outside and inside the star. The Hayward and Nielsen-Visser dynamical surface gravity are in agreement with the one resulting from the Killing vector of the outer static metric. However, these two definitions inside the star do not coincide with the Killing surface gravity outside the star when the star crosses the event horizon. This motivates us to study the surface gravity using Fodor's approach to have a unique surface gravity at the mentioned moment. Then the extremality condition and the first law of thermodynamics are discussed at the trapping horizon of the star. |
gr-qc/9611026 | Madore | J. Madore | Classical Gravity on Fuzzy Space-Time | Lecture given at the 30th International Symposium Ahrenshoop on the
Theory of Elementary Particles, Buckow, Germany, August 27-31, 1996; 11 Pages
LaTex | Nucl.Phys.Proc.Suppl. 56B (1997) 183-190 | 10.1016/S0920-5632(97)00325-3 | null | gr-qc hep-th | null | A review is made of recent efforts to find relations between the commutation
relations which define a noncommutative geometry and the gravitational field
which remains as a shadow in the commutative limit.
| [
{
"created": "Mon, 11 Nov 1996 11:11:33 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Madore",
"J.",
""
]
] | A review is made of recent efforts to find relations between the commutation relations which define a noncommutative geometry and the gravitational field which remains as a shadow in the commutative limit. |
1306.6719 | Ming-Lei Tong | Ming-Lei Tong, Bao-Rong Yan, Cheng-Shi Zhao, Dong-Shan Yin, Shu-Hong
Zhao, Ting-Gao Yang, Yu-Ping Gao | Pulsar Timing Residuals Induced by Gravitational Waves from Single
Non-evolving Supermassive Black Hole Binaries with Elliptical Orbits | 3 figures, 1 table, 7 pages, Match with the publication version and
the Erratum: Chin. Phys. Lett. 30, 119901, 2013 | Chin. Phys. Lett. 30, 100402, 2013 | 10.1088/0256-307X/30/10/100402 | NTSC/03 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The pulsar timing residuals induced by gravitational waves from non-evolving
single binary sources with general elliptical orbits will be analyzed. For
different orbital eccentricities, the timing residuals present different
properties. The standard deviations of the timing residuals induced by a fixed
gravitational wave source will be calculated for different values of the
eccentricity. We will also analyze the timing residuals of PSR J0437-4715
induced by one of the best known single gravitational wave sources, the
supermassive black hole binary in the blazar OJ287.
| [
{
"created": "Fri, 28 Jun 2013 05:26:05 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Nov 2013 03:22:43 GMT",
"version": "v2"
}
] | 2015-06-16 | [
[
"Tong",
"Ming-Lei",
""
],
[
"Yan",
"Bao-Rong",
""
],
[
"Zhao",
"Cheng-Shi",
""
],
[
"Yin",
"Dong-Shan",
""
],
[
"Zhao",
"Shu-Hong",
""
],
[
"Yang",
"Ting-Gao",
""
],
[
"Gao",
"Yu-Ping",
""
]
] | The pulsar timing residuals induced by gravitational waves from non-evolving single binary sources with general elliptical orbits will be analyzed. For different orbital eccentricities, the timing residuals present different properties. The standard deviations of the timing residuals induced by a fixed gravitational wave source will be calculated for different values of the eccentricity. We will also analyze the timing residuals of PSR J0437-4715 induced by one of the best known single gravitational wave sources, the supermassive black hole binary in the blazar OJ287. |
1502.02011 | Enrico Pajer | Liang Dai, Enrico Pajer and Fabian Schmidt | Conformal Fermi Coordinates | 43 pages, two figures. v2: minor changes, added references, expanded
subsec 3.3 | null | 10.1088/1475-7516/2015/11/043 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Fermi Normal Coordinates (FNC) are a useful frame for isolating the locally
observable, physical effects of a long-wavelength spacetime perturbation. Their
cosmological application, however, is hampered by the fact that they are only
valid on scales much smaller than the horizon. We introduce a generalization
that we call Conformal Fermi Coordinates (CFC). CFC preserve all the advantages
of FNC, but in addition are valid outside the horizon. They allow us to
calculate the coupling of long- and short-wavelength modes on all scales larger
than the sound horizon of the cosmological fluid, starting from the epoch of
inflation until today, by removing the complications of the second order
Einstein equations to a large extent, and eliminating all gauge ambiguities. As
an application, we present a calculation of the effect of long-wavelength
tensor modes on small scale density fluctuations. We recover previous results,
but clarify the physical content of the individual contributions in terms of
locally measurable effects and "projection" terms.
| [
{
"created": "Fri, 6 Feb 2015 20:08:57 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Apr 2015 12:38:05 GMT",
"version": "v2"
}
] | 2015-12-02 | [
[
"Dai",
"Liang",
""
],
[
"Pajer",
"Enrico",
""
],
[
"Schmidt",
"Fabian",
""
]
] | Fermi Normal Coordinates (FNC) are a useful frame for isolating the locally observable, physical effects of a long-wavelength spacetime perturbation. Their cosmological application, however, is hampered by the fact that they are only valid on scales much smaller than the horizon. We introduce a generalization that we call Conformal Fermi Coordinates (CFC). CFC preserve all the advantages of FNC, but in addition are valid outside the horizon. They allow us to calculate the coupling of long- and short-wavelength modes on all scales larger than the sound horizon of the cosmological fluid, starting from the epoch of inflation until today, by removing the complications of the second order Einstein equations to a large extent, and eliminating all gauge ambiguities. As an application, we present a calculation of the effect of long-wavelength tensor modes on small scale density fluctuations. We recover previous results, but clarify the physical content of the individual contributions in terms of locally measurable effects and "projection" terms. |
2207.14611 | Jose M. Isidro | P. Fernandez de Cordoba, R. Gallego Torrome, S. Gavasso and J.M.
Isidro | On the cosmological constant as a quantum operator | 7 pages | null | null | null | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | We regard the cosmological fluid within an exponentially expanding FLRW
spacetime as the probability fluid of a nonrelativistic Schroedinger field. The
scalar Schroedinger particle so described has a mass equal to the total
(baryonic plus dark) matter content of the Universe. This procedure allows a
description of the cosmological fluid by means of the operator formalism of
nonrelativistic quantum theory. Under the assumption of radial symmetry, a
quantum operator proportional to $1/r^2$ represents the cosmological constant
$\Lambda$. The experimentally measured value of $\Lambda$ is one of the
eigenvalues of $1/r^2$. Next we solve the Poisson equation $\nabla^2U=\Lambda$
for the gravitational potential $U(r)$, with the cosmological constant
$\Lambda(r)=1/r^2$ playing the role of a source term. It turns out that $U(r)$
includes, besides the standard Newtonian potential $1/r$, a correction term
proportional to $\ln r$ identical to that appearing in theories of modified
Newtonian dynamics.
| [
{
"created": "Fri, 29 Jul 2022 11:08:42 GMT",
"version": "v1"
}
] | 2022-08-01 | [
[
"de Cordoba",
"P. Fernandez",
""
],
[
"Torrome",
"R. Gallego",
""
],
[
"Gavasso",
"S.",
""
],
[
"Isidro",
"J. M.",
""
]
] | We regard the cosmological fluid within an exponentially expanding FLRW spacetime as the probability fluid of a nonrelativistic Schroedinger field. The scalar Schroedinger particle so described has a mass equal to the total (baryonic plus dark) matter content of the Universe. This procedure allows a description of the cosmological fluid by means of the operator formalism of nonrelativistic quantum theory. Under the assumption of radial symmetry, a quantum operator proportional to $1/r^2$ represents the cosmological constant $\Lambda$. The experimentally measured value of $\Lambda$ is one of the eigenvalues of $1/r^2$. Next we solve the Poisson equation $\nabla^2U=\Lambda$ for the gravitational potential $U(r)$, with the cosmological constant $\Lambda(r)=1/r^2$ playing the role of a source term. It turns out that $U(r)$ includes, besides the standard Newtonian potential $1/r$, a correction term proportional to $\ln r$ identical to that appearing in theories of modified Newtonian dynamics. |
gr-qc/9710012 | Francis Vendrell | F. Vendrell | Some exact results on the CGHS black-hole radiation | 29 pages, Latex, 1 figure | Helv.Phys.Acta 71 (1998) 314-342 | null | Imperial/TP/97-98/1 | gr-qc | null | Theorems on the emission of massless scalar particles by the CGHS black hole
are presented. The convergence of the mean number of particles created
spontaneously in an arbitrary state is studied and shown to be strongly
dependent on the infrared behavior of this state. A bound for this quantity is
given and its asymptotic forms close to the horizon and far from the black hole
are investigated. The physics of a wave packet is analysed in some detail in
the black-hole background. It is also shown that for some states the mean
number of created particles is not thermal close to the horizon. These states
have a long queue extending far from the black hole, or are unlocalised in
configuration space.
| [
{
"created": "Thu, 2 Oct 1997 14:16:23 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Vendrell",
"F.",
""
]
] | Theorems on the emission of massless scalar particles by the CGHS black hole are presented. The convergence of the mean number of particles created spontaneously in an arbitrary state is studied and shown to be strongly dependent on the infrared behavior of this state. A bound for this quantity is given and its asymptotic forms close to the horizon and far from the black hole are investigated. The physics of a wave packet is analysed in some detail in the black-hole background. It is also shown that for some states the mean number of created particles is not thermal close to the horizon. These states have a long queue extending far from the black hole, or are unlocalised in configuration space. |
0902.0573 | Leor Barack | Leor Barack and Norichika Sago | Gravitational self-force correction to the innermost stable circular
orbit of a Schwarzschild black hole | 4 pages. v2: Added clarifications re. the definition of the
conservative self-force and the gauge dependence of the frequency; some other
minor changes. Accepted for publication in PRL | Phys.Rev.Lett.102:191101,2009 | 10.1103/PhysRevLett.102.191101 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The innermost stable circular orbit (ISCO) of a test particle around a
Schwarzschild black hole of mass $M$ has (areal) radius $r_{\rm isco}= 6M
G/c^2$. If the particle is endowed with mass $\mu(\ll M)$, it experiences a
gravitational self-force whose conservative piece alters the location of the
ISCO. Here we calculate the resulting shifts $\Delta r_{\rm isco}$ and
$\Delta\Omega_{\rm isco}$ in the ISCO's radius and frequency, at leading order
in the mass ratio $\mu/M$. We obtain, in the Lorenz gauge, $\Delta r_{\rm
isco}=-3.269 (\pm 0.003)\mu G/c^2$ and $\Delta\Omega_{\rm isco}/\Omega_{\rm
isco}=0.4870 (\pm 0.0006) \mu/M$. We discuss the implications of our result
within the context of the extreme-mass-ratio binary inspiral problem.
| [
{
"created": "Tue, 3 Feb 2009 18:10:58 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Apr 2009 12:42:51 GMT",
"version": "v2"
}
] | 2009-06-30 | [
[
"Barack",
"Leor",
""
],
[
"Sago",
"Norichika",
""
]
] | The innermost stable circular orbit (ISCO) of a test particle around a Schwarzschild black hole of mass $M$ has (areal) radius $r_{\rm isco}= 6M G/c^2$. If the particle is endowed with mass $\mu(\ll M)$, it experiences a gravitational self-force whose conservative piece alters the location of the ISCO. Here we calculate the resulting shifts $\Delta r_{\rm isco}$ and $\Delta\Omega_{\rm isco}$ in the ISCO's radius and frequency, at leading order in the mass ratio $\mu/M$. We obtain, in the Lorenz gauge, $\Delta r_{\rm isco}=-3.269 (\pm 0.003)\mu G/c^2$ and $\Delta\Omega_{\rm isco}/\Omega_{\rm isco}=0.4870 (\pm 0.0006) \mu/M$. We discuss the implications of our result within the context of the extreme-mass-ratio binary inspiral problem. |
2204.02098 | Orlando Luongo | Rocco D'Agostino, Roberto Giamb\`o, Orlando Luongo | Constraining primordial black holes as a fraction of dark matter through
accretion disk luminosity | 10 pages, 6 figures, Accepted for publication in Phys. Rev. D | null | 10.1103/PhysRevD.107.043032 | null | gr-qc astro-ph.CO astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider the hypothesis that fractions of dark matter could
be constituted by primordial black holes (PBHs). To test this possibility, we
work out the observational properties of a static black hole embedded in the
dark matter envelope made of a PBH source. The corresponding modifications of
geometry due to such a physical system are investigated, with a particular
focus on the accretion disk luminosity in spiral galaxies. The impact of the
PBH presence is analyzed through modification of the disk luminosity and
kinematic quantities. Thus, we discuss possible constraints on the PBH
abundance in view of the most recent theoretical bounds. The results of our
study indicate that suitable PBH masses are
$M_\text{PBH}\in[10^6,10^{12}]M_\odot$ for PBH fractions
$f_\text{PBH}\in[10^{-3},1]$. In particular, a comparison with the predictions
of the exponential sphere density profile for dark matter suggests that the
best-matching configuration is achieved for $f_\text{PBH}=1$ and
$M_\text{PBH}=10^6 M_\odot$. Consequences with respect to the current knowledge
on primordial black hole physics are discussed.
| [
{
"created": "Tue, 5 Apr 2022 10:35:10 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Feb 2023 10:19:14 GMT",
"version": "v2"
}
] | 2023-03-08 | [
[
"D'Agostino",
"Rocco",
""
],
[
"Giambò",
"Roberto",
""
],
[
"Luongo",
"Orlando",
""
]
] | In this paper, we consider the hypothesis that fractions of dark matter could be constituted by primordial black holes (PBHs). To test this possibility, we work out the observational properties of a static black hole embedded in the dark matter envelope made of a PBH source. The corresponding modifications of geometry due to such a physical system are investigated, with a particular focus on the accretion disk luminosity in spiral galaxies. The impact of the PBH presence is analyzed through modification of the disk luminosity and kinematic quantities. Thus, we discuss possible constraints on the PBH abundance in view of the most recent theoretical bounds. The results of our study indicate that suitable PBH masses are $M_\text{PBH}\in[10^6,10^{12}]M_\odot$ for PBH fractions $f_\text{PBH}\in[10^{-3},1]$. In particular, a comparison with the predictions of the exponential sphere density profile for dark matter suggests that the best-matching configuration is achieved for $f_\text{PBH}=1$ and $M_\text{PBH}=10^6 M_\odot$. Consequences with respect to the current knowledge on primordial black hole physics are discussed. |
2207.13182 | Qasem Exirifard | Qasem Exirifard, Ebrahim Karimi | Trajectory of a massive localised wave function in a curved spacetime
geometry | 17 pages, 4 figures, matches the published version | Phys. Rev. D 107, 064059 (2023) | 10.1103/PhysRevD.107.064059 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Propagation of a localised wave function of a massive scalar field is
investigated in its rest frame. The complete orthogonal Hermite-Gauss basis is
presented, and the Gouy phase and Rayleigh scale notions are adapted. The
leading and sub-leading gravitational corrections to a localised quantum wave
function propagating in a general curved spacetime geometry are calculated
within the Fermi coordinates around the time-like geodesic of its rest frame,
and cross-talk coefficients among the modes are derived. It is observed that
spherically symmetric modes propagate along the geodesic. However,
non-spherical modes are found to experience a mode-dependent residual quantum
force at the sub-leading order. It is shown that the residual force does not
generate an escape velocity for in-falling wave functions but leads to a
mode-dependent deflection angle for the scattered ones.
| [
{
"created": "Tue, 26 Jul 2022 21:10:38 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Mar 2023 21:33:08 GMT",
"version": "v2"
}
] | 2023-03-30 | [
[
"Exirifard",
"Qasem",
""
],
[
"Karimi",
"Ebrahim",
""
]
] | Propagation of a localised wave function of a massive scalar field is investigated in its rest frame. The complete orthogonal Hermite-Gauss basis is presented, and the Gouy phase and Rayleigh scale notions are adapted. The leading and sub-leading gravitational corrections to a localised quantum wave function propagating in a general curved spacetime geometry are calculated within the Fermi coordinates around the time-like geodesic of its rest frame, and cross-talk coefficients among the modes are derived. It is observed that spherically symmetric modes propagate along the geodesic. However, non-spherical modes are found to experience a mode-dependent residual quantum force at the sub-leading order. It is shown that the residual force does not generate an escape velocity for in-falling wave functions but leads to a mode-dependent deflection angle for the scattered ones. |
1310.0410 | Gines Perez Teruel | Gin\'es R. P\'erez Teruel | Analytic solution of the algebraic equation associated to the Ricci
tensor in extended Palatini gravity | arXiv admin note: text overlap with arXiv:1101.3864, arXiv:1306.6537,
arXiv:1112.2223 by other authors | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we discuss the exact solution to the algebraic equation
associated to the Ricci tensor in the quadratic $f(R,Q)$ extension of Palatini
gravity. We show that an exact solution always exists, and in the general case
it can be found by a simple matrix diagonalization. Furthermore, the general
implications of the solution are analysed in detail, including the generation
of an effective cosmological constant, and the recovery of the $f(R)$ and
$f(Q)$ theories as particular cases in their corresponding limit. In addition,
it is proposed a power series expansion of the solution which is successfully
applied to the case of the electromagnetic field. We show that this power
series expansion may be useful to deal perturbatively with some problems in the
context of Palatini gravity.
| [
{
"created": "Tue, 1 Oct 2013 17:46:48 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Oct 2013 13:03:36 GMT",
"version": "v2"
},
{
"created": "Mon, 4 Nov 2013 13:05:41 GMT",
"version": "v3"
},
{
"created": "Wed, 16 Jul 2014 23:45:05 GMT",
"version": "v4"
}
] | 2014-07-18 | [
[
"Teruel",
"Ginés R. Pérez",
""
]
] | In this work we discuss the exact solution to the algebraic equation associated to the Ricci tensor in the quadratic $f(R,Q)$ extension of Palatini gravity. We show that an exact solution always exists, and in the general case it can be found by a simple matrix diagonalization. Furthermore, the general implications of the solution are analysed in detail, including the generation of an effective cosmological constant, and the recovery of the $f(R)$ and $f(Q)$ theories as particular cases in their corresponding limit. In addition, it is proposed a power series expansion of the solution which is successfully applied to the case of the electromagnetic field. We show that this power series expansion may be useful to deal perturbatively with some problems in the context of Palatini gravity. |
1509.06995 | Iver Brevik | I. Brevik and A. V. Timoshkin | Viscous Coupled Fluids in Inflationary Cosmology | 7 pages latex, no figures. To appear in JETP | JETP Vol. 122 (4) (2016), pp. 679-684 | 10.1134/S1063776116020023 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the inflation produced by two coupled fluids in the flat
Friedmann-Robertson-Walker universe. Different cosmological models for
describing inflation by use of an inhomogeneous equation of state for the fluid
are investigated. The gravitational equations for energy and matter are solved,
and analytic representations for the Hubble parameter and the energy density
are obtained. Corrections in the energy density for matter inducing the
inflation and the coupling with energy are discussed. We analyze the
description of inflation induced by non-constant equation-of-state parameters
from fluid viscosity. The correspondence between the spectral index and the
tensor-to-scalar ratio recently observed by the Planck satellite is considered.
| [
{
"created": "Wed, 23 Sep 2015 14:13:27 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Jan 2016 10:57:45 GMT",
"version": "v2"
},
{
"created": "Sat, 30 Jan 2016 15:44:16 GMT",
"version": "v3"
}
] | 2016-05-12 | [
[
"Brevik",
"I.",
""
],
[
"Timoshkin",
"A. V.",
""
]
] | We consider the inflation produced by two coupled fluids in the flat Friedmann-Robertson-Walker universe. Different cosmological models for describing inflation by use of an inhomogeneous equation of state for the fluid are investigated. The gravitational equations for energy and matter are solved, and analytic representations for the Hubble parameter and the energy density are obtained. Corrections in the energy density for matter inducing the inflation and the coupling with energy are discussed. We analyze the description of inflation induced by non-constant equation-of-state parameters from fluid viscosity. The correspondence between the spectral index and the tensor-to-scalar ratio recently observed by the Planck satellite is considered. |
1310.0421 | Sunil Maharaj | S Moopanar, S. D. Maharaj | Relativistic shear-free fluids with symmetry | 9 pages, To appear in J. Eng. Math. (Special issue on the
tercentenary of the Laplace-Runge-Lenz vector) | J. Eng. Math. 82: 125-131, 2013 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the complete conformal geometry of shear-free spacetimes with
spherical symmetry and do not specify the form of the matter content. The
general conformal Killing symmetry is solved and we can explicitly exhibit the
vector. The existence of a conformal symmetry places restrictions on the model.
The conditions on the gravitational potentials are expressed as a system of
integrability conditions. Timelike sectors and inheriting conformal symmetry
vectors, which map fluid flow lines conformally onto fluid flow lines, are
generated and the integrability conditions are shown to be satisfied. As an
example, a spacetime, which is expanding and accelerating, is identified which
contains a spherically symmetric conformal symmetry.
| [
{
"created": "Tue, 1 Oct 2013 18:38:29 GMT",
"version": "v1"
}
] | 2013-10-02 | [
[
"Moopanar",
"S",
""
],
[
"Maharaj",
"S. D.",
""
]
] | We study the complete conformal geometry of shear-free spacetimes with spherical symmetry and do not specify the form of the matter content. The general conformal Killing symmetry is solved and we can explicitly exhibit the vector. The existence of a conformal symmetry places restrictions on the model. The conditions on the gravitational potentials are expressed as a system of integrability conditions. Timelike sectors and inheriting conformal symmetry vectors, which map fluid flow lines conformally onto fluid flow lines, are generated and the integrability conditions are shown to be satisfied. As an example, a spacetime, which is expanding and accelerating, is identified which contains a spherically symmetric conformal symmetry. |
2206.01322 | Jansen Formiga | J. B. Formiga and V. R. Gon\c{c}alves | The generalization of the ADM gravitational energy-momentum | 21 pages | null | 10.1103/PhysRevD.106.044021 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, it is proved that the teleparallel energy-momentum generalizes
that of the ADM formalism. In doing so, it is shown that the teleparallel
$4$-momentum can be made to coincide with that of the ADM approach whenever the
ADM $4$-momentum is applicable. The only assumptions are the time gauge for the
teleparallel frame and the well-known restrictions for the coordinate system
used in the calculation of the ADM $4$-momentum. Then, examples where the ADM
formalism fails to give consist results, but the teleparallel approach does
not, are given. The advantages of the teleparallel stress-energy tensor
(density) over the pseudo-tensor of Landau-Lifshitz are exhibited. Finally, the
difficulties in identifying the gravitational angular momentum density is
discussed; it is shown that the spatial part of the proposed angular momentum
density $M^{ab}$ vanishes when the teleparallel frame satisfies the time gauge
condition.
| [
{
"created": "Thu, 2 Jun 2022 22:24:18 GMT",
"version": "v1"
}
] | 2022-08-31 | [
[
"Formiga",
"J. B.",
""
],
[
"Gonçalves",
"V. R.",
""
]
] | In this paper, it is proved that the teleparallel energy-momentum generalizes that of the ADM formalism. In doing so, it is shown that the teleparallel $4$-momentum can be made to coincide with that of the ADM approach whenever the ADM $4$-momentum is applicable. The only assumptions are the time gauge for the teleparallel frame and the well-known restrictions for the coordinate system used in the calculation of the ADM $4$-momentum. Then, examples where the ADM formalism fails to give consist results, but the teleparallel approach does not, are given. The advantages of the teleparallel stress-energy tensor (density) over the pseudo-tensor of Landau-Lifshitz are exhibited. Finally, the difficulties in identifying the gravitational angular momentum density is discussed; it is shown that the spatial part of the proposed angular momentum density $M^{ab}$ vanishes when the teleparallel frame satisfies the time gauge condition. |
gr-qc/0608105 | Lorenzo Iorio | Lorenzo Iorio | The Lense-Thirring effect and the Pioneer anomaly: Solar System tests | WS LaTex macros for proceedings, 3 pages, no figures, no tables, 31
references. Paper submitted to the Eleventh Marcel Grossmann Meeting on
General Relativity, 23-29 July, Freie Universitaet Berlin, 2006. Abridged
version to meet page limits. Some changes in the Lense-Thirrings section
including the new results from MGS. Thanks to Daniela Taeuber for useful
correspondence about the Pioneer anomaly | Proceedings of the MG11 Meeting on General Relativity, ed. H.
Kleinert, R.T. Jantzen, R. Ruffini, World Scientific, Singapore, pp.
2558-2560, 2008 | 10.1142/9789812834300_0458 | null | gr-qc astro-ph hep-ph physics.geo-ph physics.space-ph | null | We report on a \lessim 1% test of the Lense-Thirring effect with the Mars
Global Surveyor (MGS) spacecraft and on certain features of motion of Uranus,
Neptune and Pluto which contradict the hypothesis that the Pioneer anomaly can
be caused by some gravitational mechanism.
| [
{
"created": "Wed, 23 Aug 2006 09:38:51 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Sep 2006 22:13:14 GMT",
"version": "v2"
},
{
"created": "Tue, 9 Jan 2007 22:44:26 GMT",
"version": "v3"
},
{
"created": "Sat, 3 Feb 2007 00:19:36 GMT",
"version": "v4"
}
] | 2012-07-31 | [
[
"Iorio",
"Lorenzo",
""
]
] | We report on a \lessim 1% test of the Lense-Thirring effect with the Mars Global Surveyor (MGS) spacecraft and on certain features of motion of Uranus, Neptune and Pluto which contradict the hypothesis that the Pioneer anomaly can be caused by some gravitational mechanism. |
gr-qc/9412034 | null | Pedro F. Gonzalez-Diaz | Time Walk Through the Quantum Cosmic String | 26 pages, 6 figures (available upon request) | null | null | IMAFF-RC-07-94 | gr-qc | null | Enforcing the spacetime of supermassive cosmic strings to satisfy the
symmetry of a gravitational topological defect, that is a spacetime kink, it is
shown that the energy of these strings becomes quantized so that only defects
whose internal geometry is that of a hemisphere (critical string) and that of a
sphere (extreme string) are allowed. In the latter case, the exterior conical
singularity becomes an event-horizon singularity which can be removed by using
the Kruskal technique in the kink metric. It is also shown that the
geodesically complete metric of the extreme string can accommodate closed
timelike curves which are compatible with quantum theory, but cannot be noticed
by any observers. The quantum string can also drive an essentially unique
process of inflationary expansion in its core, without any fine tuning of the
initial conditions.
| [
{
"created": "Mon, 12 Dec 1994 15:04:35 GMT",
"version": "v1"
}
] | 2009-09-25 | [
[
"Gonzalez-Diaz",
"Pedro F.",
""
]
] | Enforcing the spacetime of supermassive cosmic strings to satisfy the symmetry of a gravitational topological defect, that is a spacetime kink, it is shown that the energy of these strings becomes quantized so that only defects whose internal geometry is that of a hemisphere (critical string) and that of a sphere (extreme string) are allowed. In the latter case, the exterior conical singularity becomes an event-horizon singularity which can be removed by using the Kruskal technique in the kink metric. It is also shown that the geodesically complete metric of the extreme string can accommodate closed timelike curves which are compatible with quantum theory, but cannot be noticed by any observers. The quantum string can also drive an essentially unique process of inflationary expansion in its core, without any fine tuning of the initial conditions. |
0804.3742 | Diego Meschini | Diego Meschini | A metageometric enquiry concerning time, space, and quantum physics | Ph.D. thesis, 285 pages, LaTeX. Precompiled PDF (3.86 Mb) available
at http://urn.fi/URN:ISBN:978-951-39-3192-6 | null | null | 1/2008, Department of Physics, University of Jyv\"askyl\"a, Finland | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An enquiry into the physical nature of time and space and into the ontology
of quantum mechanics from a metageometric perspective, resulting from the
belief that geometric thought and language are powerless to farther
understanding of these issues, restricting instead physical progress.
The nature and assumptions of quantum gravity are analysed critically,
including misgivings about the relevance of the Planck scale to it and its lack
of observational referent in the natural world.
The anthropic foundations of geometry are investigated. The exclusive use of
geometric thought from antiquity to present-day physics is found to permeate
all new attempts towards better theories, including quantum gravity and, within
it, even pregeometry.
The problem of the ether is found to have perpetuated itself up to the
present by transmuting its form from mechanical, through metric, to geometric.
A clarification is made of the physical, mathematical, and psychological
foundations of relativity and quantum theories. The former is founded
geometrically on measurement-based clock-reading separations ds. The latter is
founded metageometrically on the experiment-based concepts of premeasurement
and transition things, inspired in the physically unexplored aspect of time as
a consciousness-related product. A concept of metageometric time is developed
and coordinate time t is recovered from it. Discovery of the connection between
quantum-mechanical metageometric time elements and general-relativistic clock
time elements ds is deemed necessary for a combined understanding of time.
Time is conjectured to be the missing link between general relativity and
quantum mechanics.
| [
{
"created": "Wed, 23 Apr 2008 15:01:39 GMT",
"version": "v1"
}
] | 2008-04-24 | [
[
"Meschini",
"Diego",
""
]
] | An enquiry into the physical nature of time and space and into the ontology of quantum mechanics from a metageometric perspective, resulting from the belief that geometric thought and language are powerless to farther understanding of these issues, restricting instead physical progress. The nature and assumptions of quantum gravity are analysed critically, including misgivings about the relevance of the Planck scale to it and its lack of observational referent in the natural world. The anthropic foundations of geometry are investigated. The exclusive use of geometric thought from antiquity to present-day physics is found to permeate all new attempts towards better theories, including quantum gravity and, within it, even pregeometry. The problem of the ether is found to have perpetuated itself up to the present by transmuting its form from mechanical, through metric, to geometric. A clarification is made of the physical, mathematical, and psychological foundations of relativity and quantum theories. The former is founded geometrically on measurement-based clock-reading separations ds. The latter is founded metageometrically on the experiment-based concepts of premeasurement and transition things, inspired in the physically unexplored aspect of time as a consciousness-related product. A concept of metageometric time is developed and coordinate time t is recovered from it. Discovery of the connection between quantum-mechanical metageometric time elements and general-relativistic clock time elements ds is deemed necessary for a combined understanding of time. Time is conjectured to be the missing link between general relativity and quantum mechanics. |
2110.09967 | Tao Yang | Tao Yang, Hyung Mok Lee, Rong-Gen Cai, Han Gil Choi, Sunghoon Jung | Space-borne atom interferometric gravitational wave detections. Part II.
Dark sirens and finding the one | 16 pages, 6 figures, and 1 table. To match the published version | JCAP01(2022)042 | 10.1088/1475-7516/2022/01/042 | null | gr-qc astro-ph.CO astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate the potential of dark sirens by the space-borne
atom interferometric gravitational-wave detectors to probe the Hubble constant.
In the mid-frequency band, the sources live a long time. The motion of a
detector around the Sun as well as in Earth orbit would induce large Doppler
and reorientation effects, providing a precise angular resolution. Such precise
localization for the GW sources makes it possible to observe the dark sirens
with only one potential host galaxy, which are dubbed "golden dark sirens". We
construct the catalogs of golden dark sirens and estimate that there are around
79 and 35 golden dark sirens of binary neutron stars (BNS) and binary black
holes (BBH) that would be pass the detection threshold of AEDGE in 5 years. Our
results show that with 5, 10, and all 79 golden dark BNS tracked by AEDGE one
can constrain $H_0$ at 5.5\%, 4.1\%, and 1.8\% precision levels. With 5, 10,
and all 35 golden dark BBH one can constrain $H_0$ at 2.2\%, 1.8\%, and 1.5\%
precision levels, respectively. It suggests that only 5-10 golden dark BBH by
AEDGE are sufficient to arbitrate the current tension between local and
high-$z$ measurements of $H_0$.
| [
{
"created": "Tue, 19 Oct 2021 13:29:37 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Jan 2022 03:05:13 GMT",
"version": "v2"
}
] | 2022-01-24 | [
[
"Yang",
"Tao",
""
],
[
"Lee",
"Hyung Mok",
""
],
[
"Cai",
"Rong-Gen",
""
],
[
"Choi",
"Han Gil",
""
],
[
"Jung",
"Sunghoon",
""
]
] | In this paper, we investigate the potential of dark sirens by the space-borne atom interferometric gravitational-wave detectors to probe the Hubble constant. In the mid-frequency band, the sources live a long time. The motion of a detector around the Sun as well as in Earth orbit would induce large Doppler and reorientation effects, providing a precise angular resolution. Such precise localization for the GW sources makes it possible to observe the dark sirens with only one potential host galaxy, which are dubbed "golden dark sirens". We construct the catalogs of golden dark sirens and estimate that there are around 79 and 35 golden dark sirens of binary neutron stars (BNS) and binary black holes (BBH) that would be pass the detection threshold of AEDGE in 5 years. Our results show that with 5, 10, and all 79 golden dark BNS tracked by AEDGE one can constrain $H_0$ at 5.5\%, 4.1\%, and 1.8\% precision levels. With 5, 10, and all 35 golden dark BBH one can constrain $H_0$ at 2.2\%, 1.8\%, and 1.5\% precision levels, respectively. It suggests that only 5-10 golden dark BBH by AEDGE are sufficient to arbitrate the current tension between local and high-$z$ measurements of $H_0$. |
gr-qc/0002055 | Kip S. Thorne | Yuk Tung Liu and Kip S. Thorne (Theoretical Astrophysics, California
Institute of Technology, Pasadena, California) | Thermoelastic Noise and Homogeneous Thermal Noise in Finite Sized
Gravitational-Wave Test Masses | 10 pages and 3 figures; RevTeX; submitted to Physical Review D | Phys.Rev. D62 (2000) 122002 | 10.1103/PhysRevD.62.122002 | null | gr-qc cond-mat.mtrl-sci | null | An analysis is given of thermoelastic noise (thermal noise due to
thermoelastic dissipation) in finite sized test masses of laser interferometer
gravitational-wave detectors. Finite-size effects increase the thermoelastic
noise by a modest amount; for example, for the sapphire test masses tentatively
planned for LIGO-II and plausible beam-spot radii, the increase is less than or
of order 10 per cent. As a side issue, errors are pointed out in the currently
used formulas for conventional, homogeneous thermal noise (noise associated
with dissipation which is homogeneous and described by an imaginary part of the
Young's modulus) in finite sized test masses. Correction of these errors
increases the homogeneous thermal noise by less than or of order 5 per cent for
LIGO-II-type configurations.
| [
{
"created": "Wed, 16 Feb 2000 05:00:57 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Liu",
"Yuk Tung",
"",
"Theoretical Astrophysics, California\n Institute of Technology, Pasadena, California"
],
[
"Thorne",
"Kip S.",
"",
"Theoretical Astrophysics, California\n Institute of Technology, Pasadena, California"
]
] | An analysis is given of thermoelastic noise (thermal noise due to thermoelastic dissipation) in finite sized test masses of laser interferometer gravitational-wave detectors. Finite-size effects increase the thermoelastic noise by a modest amount; for example, for the sapphire test masses tentatively planned for LIGO-II and plausible beam-spot radii, the increase is less than or of order 10 per cent. As a side issue, errors are pointed out in the currently used formulas for conventional, homogeneous thermal noise (noise associated with dissipation which is homogeneous and described by an imaginary part of the Young's modulus) in finite sized test masses. Correction of these errors increases the homogeneous thermal noise by less than or of order 5 per cent for LIGO-II-type configurations. |
gr-qc/0004007 | Valerio Faraoni | Valerio Faraoni (Universite' Libre de Bruxelles) | Generalized slow-roll inflation | 14 pages, LaTeX, some typos corrected | Phys.Lett.A269:209-213,2000 | 10.1016/S0375-9601(00)00257-7 | null | gr-qc astro-ph hep-th | null | The slow-roll approximation to inflation is ultimately justified by the
presence of inflationary attractors for the orbits of the solutions of the
dynamical equations in phase space. There are many indications that the
inflaton field couples nonminimally to the spacetime curvature: the existence
of attractor points for inflation with nonminimal coupling is demonstrated,
subject to a condition on the inflaton potential and the value of the coupling
constant.
| [
{
"created": "Mon, 3 Apr 2000 16:21:43 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Apr 2000 08:24:32 GMT",
"version": "v2"
}
] | 2011-08-11 | [
[
"Faraoni",
"Valerio",
"",
"Universite' Libre de Bruxelles"
]
] | The slow-roll approximation to inflation is ultimately justified by the presence of inflationary attractors for the orbits of the solutions of the dynamical equations in phase space. There are many indications that the inflaton field couples nonminimally to the spacetime curvature: the existence of attractor points for inflation with nonminimal coupling is demonstrated, subject to a condition on the inflaton potential and the value of the coupling constant. |
gr-qc/9708002 | Robert Marsa | R. Gomez, R. L. Marsa, J. Winicour | Black hole excision with matching | 11 pages, LaTeX, 6 figures, to appear in Phys. Rev. D | Phys.Rev. D56 (1997) 6310-6319 | 10.1103/PhysRevD.56.6310 | null | gr-qc | null | We present a new method for treating the inner Cauchy boundary of a black
hole spacetime by matching to a characteristic evolution. We discuss the
advantages and disadvantages of such a scheme relative to Cauchy-only
approaches. A prototype code, for the spherically symmetric collapse of a
self-gravitating scalar field, shows that matching performs at least as well as
other approaches to handling the inner boundary.
| [
{
"created": "Fri, 1 Aug 1997 15:20:52 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Gomez",
"R.",
""
],
[
"Marsa",
"R. L.",
""
],
[
"Winicour",
"J.",
""
]
] | We present a new method for treating the inner Cauchy boundary of a black hole spacetime by matching to a characteristic evolution. We discuss the advantages and disadvantages of such a scheme relative to Cauchy-only approaches. A prototype code, for the spherically symmetric collapse of a self-gravitating scalar field, shows that matching performs at least as well as other approaches to handling the inner boundary. |
gr-qc/0006021 | D. V. Ahluwalia | G. Z. Adunas, E. Rodriguez-Milla, D. V. Ahluwalia | Probing Quantum Aspects of Gravity | Phys. Lett. B (in press). S. Sarkar's name was inadvertently missed
from the list of authors for "Nature 393 (1998) 763-765." This has been now
corrected | Phys.Lett.B485:215-223,2000 | 10.1016/S0370-2693(00)00697-3 | EdeFuAZ/ISGBG-05 | gr-qc astro-ph hep-ph hep-th quant-ph | null | We emphasize that a specific aspect of quantum gravity is the absence of a
super-selection rule that prevents a linear superposition of different
gravitational charges. As an immediate consequence, we obtain a tiny, but
observable, violation of the equivalence principle, provided, inertial and
gravitational masses are not assumed to be operationally identical objects. In
this framework, the cosmic gravitational environment affects local experiments.
A range of terrestrial experiments, from neutron interferometry to neutrino
oscillations, can serve as possible probes to study the emergent quantum
aspects of gravity.
| [
{
"created": "Tue, 6 Jun 2000 19:10:40 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Jul 2000 19:49:38 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Adunas",
"G. Z.",
""
],
[
"Rodriguez-Milla",
"E.",
""
],
[
"Ahluwalia",
"D. V.",
""
]
] | We emphasize that a specific aspect of quantum gravity is the absence of a super-selection rule that prevents a linear superposition of different gravitational charges. As an immediate consequence, we obtain a tiny, but observable, violation of the equivalence principle, provided, inertial and gravitational masses are not assumed to be operationally identical objects. In this framework, the cosmic gravitational environment affects local experiments. A range of terrestrial experiments, from neutron interferometry to neutrino oscillations, can serve as possible probes to study the emergent quantum aspects of gravity. |
2205.06023 | Tatsuya Narikawa | Tatsuya Narikawa and Nami Uchikata | Follow-up analyses of the binary-neutron-star signals GW170817 and
GW190425 by using post-Newtonian waveform models | 18 pages, 9 figures, Accepted for publication in Physical Review D | Phys. Rev. D 106, 103006 (2022) | 10.1103/PhysRevD.106.103006 | LIGO-P2200066 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We reanalyze the binary-neutron-star signals, GW170817 and GW190425, focusing
on the inspiral regime to avoid uncertainties on waveform modeling in the
postinspiral regime. We use post-Newtonian waveform models as templates, which
are theoretically rigid and efficiently describe the inspiral regime. We study
potential systematic difference in estimates of the binary tidal deformability
$\tilde{\Lambda}$ by using different descriptions for the point-particle
dynamics and tidal effects. We find that the estimates of $\tilde{\Lambda}$
show no significant systematic difference among three models for the
point-particle parts: TF2, TF2g, and TF2+, when they employ the same tidal
model. We compare different tidal descriptions given by different
post-Newtonian orders in the tidal phase. Our results indicate that the
estimates of $\tilde{\Lambda}$ slightly depend on the post-Newtonian order in
the tidal phase and an increase in the tidal post-Newtonian order does not lead
to a monotonic change in the estimate of $\tilde{\Lambda}$. We also compare the
estimate of $\tilde{\Lambda}$ obtained by the post-Newtonian tidal model and
numerical-relativity calibrated tidal models. We find that the post-Newtonian
model gives slightly larger estimate of $\tilde{\Lambda}$ and wider posterior
distribution than the numerical-relativity calibrated models. According to
Bayesian model comparison, it is difficult to identify a preference among the
post-Newtonian orders by relying on the GW170817 and GW190425 data. Our results
indicate no preference among numerical-relativity calibrated tidal models over
the post-Newtonian model. Additionally, we present constraints on
equation-of-state models for neutron stars with the post-Newtonian model, which
show that the GW170817 data disfavor less compact models, though they are
slightly weaker constraints than the numerical-relativity calibrated tidal
models.
| [
{
"created": "Thu, 12 May 2022 11:11:20 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Oct 2022 05:08:08 GMT",
"version": "v2"
}
] | 2022-11-08 | [
[
"Narikawa",
"Tatsuya",
""
],
[
"Uchikata",
"Nami",
""
]
] | We reanalyze the binary-neutron-star signals, GW170817 and GW190425, focusing on the inspiral regime to avoid uncertainties on waveform modeling in the postinspiral regime. We use post-Newtonian waveform models as templates, which are theoretically rigid and efficiently describe the inspiral regime. We study potential systematic difference in estimates of the binary tidal deformability $\tilde{\Lambda}$ by using different descriptions for the point-particle dynamics and tidal effects. We find that the estimates of $\tilde{\Lambda}$ show no significant systematic difference among three models for the point-particle parts: TF2, TF2g, and TF2+, when they employ the same tidal model. We compare different tidal descriptions given by different post-Newtonian orders in the tidal phase. Our results indicate that the estimates of $\tilde{\Lambda}$ slightly depend on the post-Newtonian order in the tidal phase and an increase in the tidal post-Newtonian order does not lead to a monotonic change in the estimate of $\tilde{\Lambda}$. We also compare the estimate of $\tilde{\Lambda}$ obtained by the post-Newtonian tidal model and numerical-relativity calibrated tidal models. We find that the post-Newtonian model gives slightly larger estimate of $\tilde{\Lambda}$ and wider posterior distribution than the numerical-relativity calibrated models. According to Bayesian model comparison, it is difficult to identify a preference among the post-Newtonian orders by relying on the GW170817 and GW190425 data. Our results indicate no preference among numerical-relativity calibrated tidal models over the post-Newtonian model. Additionally, we present constraints on equation-of-state models for neutron stars with the post-Newtonian model, which show that the GW170817 data disfavor less compact models, though they are slightly weaker constraints than the numerical-relativity calibrated tidal models. |
0812.2138 | Prado Martin-Moruno | S. Capozziello, P. Martin-Moruno and C. Rubano | Exact $f(R)$-cosmological model coming from the request of the existence
of a Noether symmetry | 4 pages, 2 figures, Contribution to the proceedings of Spanish
Relativity Meeting 2008, Salamanca, Sapin, 15-19 September 2008 | AIP Conf.Proc.1122:213-216,2009 | 10.1063/1.3141262 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an $f(R)$-cosmological model with an exact analytic solution,
coming from the request of the existence of a Noether symmetry, which is able
to describe a dust-dominated decelerated phase before the current accelerated
phase of the universe.
| [
{
"created": "Thu, 11 Dec 2008 13:01:44 GMT",
"version": "v1"
}
] | 2009-11-05 | [
[
"Capozziello",
"S.",
""
],
[
"Martin-Moruno",
"P.",
""
],
[
"Rubano",
"C.",
""
]
] | We present an $f(R)$-cosmological model with an exact analytic solution, coming from the request of the existence of a Noether symmetry, which is able to describe a dust-dominated decelerated phase before the current accelerated phase of the universe. |
2403.08957 | Mick Wright | Mick Wright, Justin Janquart, Nathan Johnson-McDaniel | Effect of Deviations from General Relativity on Searches for
Gravitational Wave Microlensing and Type II Strong Lensing | null | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | As the gravitational wave detector network is upgraded and the sensitivity of
the detectors improves, novel scientific avenues open for exploration. For
example, tests of general relativity will become more accurate as smaller
deviations can be probed. Additionally, the detection of lensed gravitational
waves becomes more likely. However, these new avenues could also interact with
each other, and a gravitational wave event presenting deviations from general
relativity could be mistaken for a lensed one. Here, we explore how
phenomenological deviations from general relativity or binaries of exotic
compact objects could impact those lensing searches focusing on a single event.
We consider strong lensing, millilensing, and microlensing and find that
certain phenomenological deviations from general relativity may be mistaken for
all of these types of lensing. Therefore, our study shows that future candidate
lensing events would need to be carefully examined to avoid a false claim of
lensing where instead a deviation from general relativity has been seen.
| [
{
"created": "Wed, 13 Mar 2024 20:52:39 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Mar 2024 17:30:47 GMT",
"version": "v2"
}
] | 2024-03-27 | [
[
"Wright",
"Mick",
""
],
[
"Janquart",
"Justin",
""
],
[
"Johnson-McDaniel",
"Nathan",
""
]
] | As the gravitational wave detector network is upgraded and the sensitivity of the detectors improves, novel scientific avenues open for exploration. For example, tests of general relativity will become more accurate as smaller deviations can be probed. Additionally, the detection of lensed gravitational waves becomes more likely. However, these new avenues could also interact with each other, and a gravitational wave event presenting deviations from general relativity could be mistaken for a lensed one. Here, we explore how phenomenological deviations from general relativity or binaries of exotic compact objects could impact those lensing searches focusing on a single event. We consider strong lensing, millilensing, and microlensing and find that certain phenomenological deviations from general relativity may be mistaken for all of these types of lensing. Therefore, our study shows that future candidate lensing events would need to be carefully examined to avoid a false claim of lensing where instead a deviation from general relativity has been seen. |
gr-qc/9211005 | null | M. De Francia, G. Goya, R. C. Mercader and H. Vucetich | M\"o\ss{}bauer null redshift experiment II | LaTeX, 8 pages, 1 figure (included), LAPLATA- | null | null | null | gr-qc | null | Accurate limits for the violation of the Principle of Equivalence have been
found from the comparison of the redshifts of two identical nuclear species in
different chemical environments.
| [
{
"created": "Wed, 4 Nov 1992 14:16:31 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"De Francia",
"M.",
""
],
[
"Goya",
"G.",
""
],
[
"Mercader",
"R. C.",
""
],
[
"Vucetich",
"H.",
""
]
] | Accurate limits for the violation of the Principle of Equivalence have been found from the comparison of the redshifts of two identical nuclear species in different chemical environments. |
gr-qc/0206011 | Nobuaki Sato | N.Sato, T.Haruyama, N.Kanda, K.Kuroda, S.Miyoki, M.Ohashi, Y.Saito,
T.Shintomi, T.Suzuki, D.Tatsumi, C.Taylor, T.Tomaru, T.Uchiyama, A.Yamamoto | Force measurements of a superconducting-film actuator for a cryogenic
interferometric gravitational-wave detector | 9 pages, 3 figures | Cryogenics 43 (2003) 425-429 | 10.1016/S0011-2275(03)00097-3 | null | gr-qc | null | We measured forces applied by an actuator with a YBCO film at near 77 K for
the Large-scale Cryogenic Gravitational-wave Telescope (LCGT) project. An
actuator consisting of both a YBCO film of 1.6 micrometers thickness and 0.81
square centimeters area and a solenoid coil exerted a force of up to 0.2 mN on
a test mass. The presented actuator system can be used to displace the mirror
of LCGT for fringe lock of the interferometer.
| [
{
"created": "Tue, 4 Jun 2002 06:54:05 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Sato",
"N.",
""
],
[
"Haruyama",
"T.",
""
],
[
"Kanda",
"N.",
""
],
[
"Kuroda",
"K.",
""
],
[
"Miyoki",
"S.",
""
],
[
"Ohashi",
"M.",
""
],
[
"Saito",
"Y.",
""
],
[
"Shintomi",
"T.",
""
]... | We measured forces applied by an actuator with a YBCO film at near 77 K for the Large-scale Cryogenic Gravitational-wave Telescope (LCGT) project. An actuator consisting of both a YBCO film of 1.6 micrometers thickness and 0.81 square centimeters area and a solenoid coil exerted a force of up to 0.2 mN on a test mass. The presented actuator system can be used to displace the mirror of LCGT for fringe lock of the interferometer. |
gr-qc/9705084 | Martin Rainer | M. Rainer | Regularized Algebraic Nets for General Covariant QFT on Differentiable
Manifolds | 13 pages, LaTeX, rejected by Class. Quant. Grav., revised | null | null | Uni-P-Math/96-17 | gr-qc | null | Quantum general relativity may be considered as generally covariant QFT on
differentiable manifolds, without any a priori metric structure. The
kinematically covariance group acts by general diffeomorphisms on the manifold
and by automorphisms on the isotonic net of *-algebras encoding the QFT, while
the algebra of observables is covariant under the dynamical subgroup of the
general diffeomorphism group.
Here, I focus on an algebraic implementation of the dynamical subgroup of
dilations. Introducing an small and large scale cutoffs algebraically, their
usual a priori conflict with general covariance is avoided. Thereby, a
commutant duality between the minimal and maximal algebra is proposed. This
allows to extract the modular structure, which is again related to the
dilations.
| [
{
"created": "Fri, 30 May 1997 22:24:18 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Rainer",
"M.",
""
]
] | Quantum general relativity may be considered as generally covariant QFT on differentiable manifolds, without any a priori metric structure. The kinematically covariance group acts by general diffeomorphisms on the manifold and by automorphisms on the isotonic net of *-algebras encoding the QFT, while the algebra of observables is covariant under the dynamical subgroup of the general diffeomorphism group. Here, I focus on an algebraic implementation of the dynamical subgroup of dilations. Introducing an small and large scale cutoffs algebraically, their usual a priori conflict with general covariance is avoided. Thereby, a commutant duality between the minimal and maximal algebra is proposed. This allows to extract the modular structure, which is again related to the dilations. |
2312.16838 | Lau Loi So | Lau Loi So | The gravitational energy-momentum for the super-energy Bel-Robinson
tensor | 4 pages | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Describing the gravitational energy-momentum, the super-energy Bel-Robinson
tensor is the best candidate. In the past, people seems only explore the lowest
order: the electric part $E_{ab}$ and magnetic part $B_{ab}$ for the Riemann
tensor. These two components are related with the static case, however, for the
energy transfer situation, one may need to consider the time varying
$\dot{E}_{ab}$ and $\dot{B}_{ab}$. Here we use $(\dot{E}_{ab},\dot{B}_{ab}$) to
study the energy-momentum for the Bel-Robinson tensor in a small sphere limit.
Meanwhile, our result illustrates how the gravitational field carries the
4-momentum including this extra information.
| [
{
"created": "Thu, 28 Dec 2023 05:53:32 GMT",
"version": "v1"
}
] | 2023-12-29 | [
[
"So",
"Lau Loi",
""
]
] | Describing the gravitational energy-momentum, the super-energy Bel-Robinson tensor is the best candidate. In the past, people seems only explore the lowest order: the electric part $E_{ab}$ and magnetic part $B_{ab}$ for the Riemann tensor. These two components are related with the static case, however, for the energy transfer situation, one may need to consider the time varying $\dot{E}_{ab}$ and $\dot{B}_{ab}$. Here we use $(\dot{E}_{ab},\dot{B}_{ab}$) to study the energy-momentum for the Bel-Robinson tensor in a small sphere limit. Meanwhile, our result illustrates how the gravitational field carries the 4-momentum including this extra information. |
0806.1707 | Paul Frampton | Paul H. Frampton | High Longevity Microlensing Events and Dark Matter Black Holes | Table clarified | null | null | null | gr-qc astro-ph hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational microlensing has been employed to identify massive halo objects
by their amplification of distant sources; MACHO searches have studied event
times $2 h \lesssim t_0 \lesssim 2 y$ corresponding masses in the range
$10^{-6} M_{\odot} \lesssim M \lesssim 100 M_{\odot}$. We suggest that larger
masses up to $10^6 M_{\odot}$ are also of considerable interest. It has not
been excluded that there is a significant number of halo black holes with such
high masses as suggested by cosmological entropy considerations and potentially
detectable by high longevity microlensing events.
| [
{
"created": "Tue, 10 Jun 2008 17:05:09 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Aug 2008 00:12:16 GMT",
"version": "v2"
},
{
"created": "Thu, 21 Aug 2008 12:37:52 GMT",
"version": "v3"
},
{
"created": "Sat, 23 Aug 2008 01:20:19 GMT",
"version": "v4"
},
{
"c... | 2008-12-27 | [
[
"Frampton",
"Paul H.",
""
]
] | Gravitational microlensing has been employed to identify massive halo objects by their amplification of distant sources; MACHO searches have studied event times $2 h \lesssim t_0 \lesssim 2 y$ corresponding masses in the range $10^{-6} M_{\odot} \lesssim M \lesssim 100 M_{\odot}$. We suggest that larger masses up to $10^6 M_{\odot}$ are also of considerable interest. It has not been excluded that there is a significant number of halo black holes with such high masses as suggested by cosmological entropy considerations and potentially detectable by high longevity microlensing events. |
2312.09047 | Yu-Cun Xie | Yu-Cun Xie, Jen-Tsung Hsiang, Bei-Lok Hu | Dynamical Vacuum Compressibility of Space | V2: Added representative references to emergent gravity, highlighting
Refs. [43-44] which are closest to the intent of this paper. No alteration of
results or derivations from v1 | Phys. Rev. D 109, 065027 (2024) | 10.1103/PhysRevD.109.065027 | null | gr-qc cond-mat.stat-mech hep-th quant-ph | http://creativecommons.org/licenses/by/4.0/ | This paper continues the investigation initiated in arXiv:2204.08634 into the
quantum thermodynamic properties of space by deriving the vacuum
compressibility of a variety of dynamical spacetimes containing massive and
massless conformally coupled quantum fields. The quantum processes studied here
include particle creation, Casimir effect, and the trace anomaly. The spaces
include $S^2, S^3$, and $T^3$ with prescribed time evolution and $S^1$, where
the temporal developments are backreaction determined. Vacuum compressibility
belongs to the same group of quantum thermodynamic / mechanical response
functions as vacuum viscosity, a concept first proposed in 1970 by Zel'dovich
for capturing the effects of vacuum particle production on the dynamics of the
early universe, made precise by rigorous work of many authors in the following
decade using quantum field theory in curved spacetime methodologies and
semiclassical gravity theory for treating backreaction effects. Various
subtleties in understanding the behavior of the vacuum energies of quantum
field origins, negative pressures and novel complicated features of dynamical
compressibility are discussed.
| [
{
"created": "Thu, 14 Dec 2023 15:46:53 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Dec 2023 14:37:14 GMT",
"version": "v2"
}
] | 2024-03-29 | [
[
"Xie",
"Yu-Cun",
""
],
[
"Hsiang",
"Jen-Tsung",
""
],
[
"Hu",
"Bei-Lok",
""
]
] | This paper continues the investigation initiated in arXiv:2204.08634 into the quantum thermodynamic properties of space by deriving the vacuum compressibility of a variety of dynamical spacetimes containing massive and massless conformally coupled quantum fields. The quantum processes studied here include particle creation, Casimir effect, and the trace anomaly. The spaces include $S^2, S^3$, and $T^3$ with prescribed time evolution and $S^1$, where the temporal developments are backreaction determined. Vacuum compressibility belongs to the same group of quantum thermodynamic / mechanical response functions as vacuum viscosity, a concept first proposed in 1970 by Zel'dovich for capturing the effects of vacuum particle production on the dynamics of the early universe, made precise by rigorous work of many authors in the following decade using quantum field theory in curved spacetime methodologies and semiclassical gravity theory for treating backreaction effects. Various subtleties in understanding the behavior of the vacuum energies of quantum field origins, negative pressures and novel complicated features of dynamical compressibility are discussed. |
gr-qc/9806048 | Andrew P. Billyard | B. J. Carr, A. A. Coley | Self-Similarity in General Relativity \endtitle | TeX document, 53 pages | Class.Quant.Grav.16:R31-R71,1999 | 10.1088/0264-9381/16/7/201 | QMW-MATHS 32 | gr-qc | null | The different kinds of self-similarity in general relativity are discussed,
with special emphasis on similarity of the ``first'' kind, corresponding to
spacetimes admitting a homothetic vector. We then survey the various classes of
self-similar solutions to Einstein's field equations and the different
mathematical approaches used in studying them. We focus mainly on spatially
homogenous and spherically symmetric self-similar solutions, emphasizing their
possible roles as asymptotic states for more general models. Perfect fluid
spherically symmetric similarity solutions have recently been completely
classified, and we discuss various astrophysical and cosmological applications
of such solutions. Finally we consider more general types of self-similar
models.
| [
{
"created": "Tue, 9 Jun 1998 15:32:05 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Carr",
"B. J.",
""
],
[
"Coley",
"A. A.",
""
]
] | The different kinds of self-similarity in general relativity are discussed, with special emphasis on similarity of the ``first'' kind, corresponding to spacetimes admitting a homothetic vector. We then survey the various classes of self-similar solutions to Einstein's field equations and the different mathematical approaches used in studying them. We focus mainly on spatially homogenous and spherically symmetric self-similar solutions, emphasizing their possible roles as asymptotic states for more general models. Perfect fluid spherically symmetric similarity solutions have recently been completely classified, and we discuss various astrophysical and cosmological applications of such solutions. Finally we consider more general types of self-similar models. |
gr-qc/9709061 | Inigo L. Egusquiza | I.L. Egusquiza, A. Feinstein, M.A. Perez Sebastian and M.A. Valle
Basagoiti | On the Entropy and the Density Matrix of Cosmological Perturbations | LaTeX2e with the epsf package | Class.Quant.Grav.15:1927-1936,1998 | 10.1088/0264-9381/15/7/010 | EHU-FT/9705 | gr-qc | null | We look at the transition to the semiclassical behaviour and the decoherence
process for the inhomogeneous perturbations in the inflationary universe. Two
different decoherence mechanisms appear: one dynamical, accompanied with a
negligible, if at all, entropy gain, and the other, effectively irreversible
dephasing, due to a rapid variation in time of the off-diagonal density matrix
elements in the post-inflationary epoch. We thus settle the discrepancies in
the entropy content of perturbations evaluated by different authors.
| [
{
"created": "Wed, 24 Sep 1997 14:11:55 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Egusquiza",
"I. L.",
""
],
[
"Feinstein",
"A.",
""
],
[
"Sebastian",
"M. A. Perez",
""
],
[
"Basagoiti",
"M. A. Valle",
""
]
] | We look at the transition to the semiclassical behaviour and the decoherence process for the inhomogeneous perturbations in the inflationary universe. Two different decoherence mechanisms appear: one dynamical, accompanied with a negligible, if at all, entropy gain, and the other, effectively irreversible dephasing, due to a rapid variation in time of the off-diagonal density matrix elements in the post-inflationary epoch. We thus settle the discrepancies in the entropy content of perturbations evaluated by different authors. |
2010.12549 | Sebastian Szybka | Sebastian J. Szybka and Syed U. Naqvi | Freely falling bodies in a standing-wave spacetime | 23 pages, 8 figures; minor changes to match published version | Phys. Rev. D 103, 024011 (2021) | 10.1103/PhysRevD.103.024011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the motion of free masses subject to the influence of standing
gravitational waves in the polarized Gowdy cosmology with a three-torus
topology. We show that antinodes attract freely falling particles and we trace
the velocity memory effect.
| [
{
"created": "Fri, 23 Oct 2020 17:17:29 GMT",
"version": "v1"
},
{
"created": "Sun, 7 Nov 2021 14:28:11 GMT",
"version": "v2"
}
] | 2021-11-09 | [
[
"Szybka",
"Sebastian J.",
""
],
[
"Naqvi",
"Syed U.",
""
]
] | We study the motion of free masses subject to the influence of standing gravitational waves in the polarized Gowdy cosmology with a three-torus topology. We show that antinodes attract freely falling particles and we trace the velocity memory effect. |
1311.0692 | Naqing Xie | Fei-hung Ho, Jian-liang Liu, and Naqing Xie | Localized Penrose inequality for the Liu-Yau mass in spherical symmetry | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For an asymptotically flat initial data, the Penrose inequality gives a lower
bound of the Arnowitt-Deser-Misner total mass of a spacetime in terms of the
area of certain surfaces representing black holes. This is a deep and beautiful
refinement of the famous positive mass theorem and it plays an important role
in the study of gravitational collapse. Gravitational collapse can also happen
if sufficient mass is concentrated into a finite region. This motivates us to
seek a localized version of the Penrose inequality. In this Letter, we
successfully make a precise statement of this form for the Liu-Yau quasi-local
mass in spherical symmetry.
| [
{
"created": "Mon, 4 Nov 2013 13:25:18 GMT",
"version": "v1"
}
] | 2013-11-05 | [
[
"Ho",
"Fei-hung",
""
],
[
"Liu",
"Jian-liang",
""
],
[
"Xie",
"Naqing",
""
]
] | For an asymptotically flat initial data, the Penrose inequality gives a lower bound of the Arnowitt-Deser-Misner total mass of a spacetime in terms of the area of certain surfaces representing black holes. This is a deep and beautiful refinement of the famous positive mass theorem and it plays an important role in the study of gravitational collapse. Gravitational collapse can also happen if sufficient mass is concentrated into a finite region. This motivates us to seek a localized version of the Penrose inequality. In this Letter, we successfully make a precise statement of this form for the Liu-Yau quasi-local mass in spherical symmetry. |
0807.5114 | Christian Corda | Christian Corda | On the longitudinal response function of interferometers for massive
gravitational waves from a bimetric theory of gravity | Final version published in Astrophysics and Space Science 0004-640X
(Print) 1572-946X (Online) | Astrophys.Space Sci.317:95-106,2008 | 10.1007/s10509-008-9860-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, some papers in the literature have shown that, from a bimetric
theory of gravity, it is possible to produce massive gravitational waves which
generate a longitudinal component in a particular polarization of the wave.
After a review of previous works, in this paper the longitudinal response
function of interferometers for this particular polarization of the wave is
computed in two different gauges, showing the gauge invariance, and in its full
frequency dependence, with specific application to the Virgo and LIGO
interferometers.
| [
{
"created": "Thu, 31 Jul 2008 17:21:31 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Aug 2008 07:39:42 GMT",
"version": "v2"
},
{
"created": "Tue, 26 Aug 2008 07:39:09 GMT",
"version": "v3"
}
] | 2009-03-12 | [
[
"Corda",
"Christian",
""
]
] | Recently, some papers in the literature have shown that, from a bimetric theory of gravity, it is possible to produce massive gravitational waves which generate a longitudinal component in a particular polarization of the wave. After a review of previous works, in this paper the longitudinal response function of interferometers for this particular polarization of the wave is computed in two different gauges, showing the gauge invariance, and in its full frequency dependence, with specific application to the Virgo and LIGO interferometers. |
1512.01450 | Alex Kirillov | A.A. Kirillov, E.P. Savelova | Cosmological wormholes | null | null | 10.1142/S0218271816500759 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe in details the procedure how the Lobachevsky space can be
factorized to a space of the constant negative curvature filled with a gas of
wormholes. We show that such wormholes have throat sections in the form of tori
and are traversable and stable in the cosmological context. The relation of
such wormholes to the dark matter phenomenon is briefly described. We also
discuss the possibility of the existence of analogous factorizations for all
types of homogeneous spaces.
| [
{
"created": "Thu, 3 Dec 2015 06:46:03 GMT",
"version": "v1"
}
] | 2016-05-10 | [
[
"Kirillov",
"A. A.",
""
],
[
"Savelova",
"E. P.",
""
]
] | We describe in details the procedure how the Lobachevsky space can be factorized to a space of the constant negative curvature filled with a gas of wormholes. We show that such wormholes have throat sections in the form of tori and are traversable and stable in the cosmological context. The relation of such wormholes to the dark matter phenomenon is briefly described. We also discuss the possibility of the existence of analogous factorizations for all types of homogeneous spaces. |
2003.10552 | Vincent Desjacques | Vincent Desjacques, Evgeni Grishin, Yonadav Barry Ginat | Axion oscillations in binary systems: angle-action surgery | 15 pages, 5 figures (v2): moderate revision. matches the published
manuscript (v3): references added | null | 10.3847/1538-4357/abaefc | null | gr-qc astro-ph.CO astro-ph.GA astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Scalar, tensor waves induce oscillatory perturbations in Keplerian systems
that can be probed with measurements of pulsar timing residuals. In this paper,
we consider the imprint of coherent oscillations produced by ultralight axion
dark matter on the Roemer time delay. We use the angle-action formalism to
calculate the time evolution of the observed signal and its dependence on the
orbital parameters and the axion phase. We derive exact analytical expressions
for arbitrary binary pulsar mass ratio and eccentricity, alleviating the need
for long numerical integrations. We emphasize the similarity of the expected
signal-to-noise ratio with the response of a harmonic oscillator to an external
oscillatory driving. We validate our theoretical predictions with numerical
simulations. Our results furnish a useful benchmark for numerical codes and
analysis procedures and, hopefully, will motivate the search for such imprints
in real data.
| [
{
"created": "Mon, 23 Mar 2020 21:09:24 GMT",
"version": "v1"
},
{
"created": "Sun, 11 Oct 2020 15:12:18 GMT",
"version": "v2"
},
{
"created": "Tue, 13 Oct 2020 11:00:23 GMT",
"version": "v3"
}
] | 2020-10-14 | [
[
"Desjacques",
"Vincent",
""
],
[
"Grishin",
"Evgeni",
""
],
[
"Ginat",
"Yonadav Barry",
""
]
] | Scalar, tensor waves induce oscillatory perturbations in Keplerian systems that can be probed with measurements of pulsar timing residuals. In this paper, we consider the imprint of coherent oscillations produced by ultralight axion dark matter on the Roemer time delay. We use the angle-action formalism to calculate the time evolution of the observed signal and its dependence on the orbital parameters and the axion phase. We derive exact analytical expressions for arbitrary binary pulsar mass ratio and eccentricity, alleviating the need for long numerical integrations. We emphasize the similarity of the expected signal-to-noise ratio with the response of a harmonic oscillator to an external oscillatory driving. We validate our theoretical predictions with numerical simulations. Our results furnish a useful benchmark for numerical codes and analysis procedures and, hopefully, will motivate the search for such imprints in real data. |
2311.15749 | Herondy Mota | E. J. B. Ferreira and H. F. Santana Mota | Quantum Brownian motion induced by a scalar field in Einstein's universe | 16 pages, 2 Figures, 2 Tables. Version accepted for publication in
EPJC | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The Brownian motion of a point particle induced by quantum vacuum
fluctuations of a massless real scalar field in Einstein's universe is studied.
By assuming the small displacement condition, the dispersion in the momentum
and position of a point particle coupled to the massless scalar field are
obtained. As a consequence of the homogeneity and isotropy properties of the
Einstein's Universe, we find that all components of these physical observables
are identical. We also examine divergent behaviors associated to the physical
momentum and position dispersions, which we attribute to the $R^1\times S^3$
compact topology of the spacetime. Finally, based on the small displacement
condition assumed, we analyze the limit of validity of our investigation.
| [
{
"created": "Mon, 27 Nov 2023 12:06:39 GMT",
"version": "v1"
},
{
"created": "Mon, 8 Apr 2024 16:05:41 GMT",
"version": "v2"
}
] | 2024-04-09 | [
[
"Ferreira",
"E. J. B.",
""
],
[
"Mota",
"H. F. Santana",
""
]
] | The Brownian motion of a point particle induced by quantum vacuum fluctuations of a massless real scalar field in Einstein's universe is studied. By assuming the small displacement condition, the dispersion in the momentum and position of a point particle coupled to the massless scalar field are obtained. As a consequence of the homogeneity and isotropy properties of the Einstein's Universe, we find that all components of these physical observables are identical. We also examine divergent behaviors associated to the physical momentum and position dispersions, which we attribute to the $R^1\times S^3$ compact topology of the spacetime. Finally, based on the small displacement condition assumed, we analyze the limit of validity of our investigation. |
1810.07407 | Arvin Ravanpak | Arvin Ravanpak and Golnaz Farpour Fadakar | Stability Analysis of DGP Brane-world Model with Agegraphic Dark Energy | null | Can. J. Phys. 98, 778 (2020) | 10.1139/cjp-2019-0305 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The aim of this work is to apply the dynamical system approach to study the
linear dynamics of the normal DGP brane-world model with agegraphic dark
energy. The stability analysis of the model will be investigated and the phase
plane portrait will be illustrated. The nature of critical points will be
analyzed by evaluating the eigenvalues of a linearized Jacobi matrix. Also, the
statefinder diagnostic procedure will be applied to show the slight deviation
from the {\Lambda}CDM model. One of the most interesting results of this work
is the great alleviation of the coincidence problem.
| [
{
"created": "Wed, 17 Oct 2018 07:20:22 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Sep 2020 20:23:15 GMT",
"version": "v2"
}
] | 2020-10-07 | [
[
"Ravanpak",
"Arvin",
""
],
[
"Fadakar",
"Golnaz Farpour",
""
]
] | The aim of this work is to apply the dynamical system approach to study the linear dynamics of the normal DGP brane-world model with agegraphic dark energy. The stability analysis of the model will be investigated and the phase plane portrait will be illustrated. The nature of critical points will be analyzed by evaluating the eigenvalues of a linearized Jacobi matrix. Also, the statefinder diagnostic procedure will be applied to show the slight deviation from the {\Lambda}CDM model. One of the most interesting results of this work is the great alleviation of the coincidence problem. |
1711.08706 | Tim-Torben Paetz | Marc Mars, Tim-Torben Paetz, Jos\'e M. M. Senovilla | The limit of Kerr-de Sitter spacetime with infinite angular-momentum
parameter $a$ | 24 pages | Phys. Rev. D 97, 024021 (2018) | 10.1103/PhysRevD.97.024021 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the limit $a\rightarrow \infty$ of the Kerr-de Sitter spacetime.
The spacetime is a Petrov type-D solution of the vacuum Einstein field
equations with a positive cosmological constant $\Lambda$, vanishing Mars-Simon
tensor and conformally flat scri. It possesses an Abelian 2-dimensional group
of symmetries whose orbits are spacelike or timelike in different regions, and
it includes, as a particular case, de Sitter spacetime. The global structure of
the solution is analyzed in detail, with particular attention to its Killing
horizons: they are foliated by non-compact marginally trapped surfaces of
finite area, and one of them `touches' the curvature singularity, which
resembles a null 2-dimensional surface. Outside the region between these
horizons there exist trapped surfaces that again are non-compact. The solution
contains, apart from $\Lambda$, a unique free parameter which can be related to
the angular momentum of the non-singular horizon in a precise way. A maximal
extension of the (axis of the) spacetime is explicitly built. We also analyze
the structure of scri, whose topology is $\mathbb{R}^3$.
| [
{
"created": "Thu, 23 Nov 2017 14:28:03 GMT",
"version": "v1"
}
] | 2018-01-24 | [
[
"Mars",
"Marc",
""
],
[
"Paetz",
"Tim-Torben",
""
],
[
"Senovilla",
"José M. M.",
""
]
] | We consider the limit $a\rightarrow \infty$ of the Kerr-de Sitter spacetime. The spacetime is a Petrov type-D solution of the vacuum Einstein field equations with a positive cosmological constant $\Lambda$, vanishing Mars-Simon tensor and conformally flat scri. It possesses an Abelian 2-dimensional group of symmetries whose orbits are spacelike or timelike in different regions, and it includes, as a particular case, de Sitter spacetime. The global structure of the solution is analyzed in detail, with particular attention to its Killing horizons: they are foliated by non-compact marginally trapped surfaces of finite area, and one of them `touches' the curvature singularity, which resembles a null 2-dimensional surface. Outside the region between these horizons there exist trapped surfaces that again are non-compact. The solution contains, apart from $\Lambda$, a unique free parameter which can be related to the angular momentum of the non-singular horizon in a precise way. A maximal extension of the (axis of the) spacetime is explicitly built. We also analyze the structure of scri, whose topology is $\mathbb{R}^3$. |
gr-qc/0005008 | Vladimir Dzhunushaliev | V.Dzhunushaliev | Wormhole with Quantum Throat | essential change in the text: title, the goal of the paper is
concentrated on constructing of the wormhole with quantum throat | Grav.Cosmol. 7 (2001) 79-82 | null | null | gr-qc hep-th | null | A wormhole with a quantum throat on the basis of an approximate model of the
spacetime foam is presented. An effective spinor field is introduced for the
description of the spacetime foam. The consequences of such model of the
wormhole is preventing a "naked'' singularity in the Reissner-Nordstr\"om
solution with $|e|/m > 1$.
| [
{
"created": "Tue, 2 May 2000 11:32:40 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Sep 2000 02:02:23 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Dzhunushaliev",
"V.",
""
]
] | A wormhole with a quantum throat on the basis of an approximate model of the spacetime foam is presented. An effective spinor field is introduced for the description of the spacetime foam. The consequences of such model of the wormhole is preventing a "naked'' singularity in the Reissner-Nordstr\"om solution with $|e|/m > 1$. |
1803.09783 | Maximiliano Isi | Maximiliano Isi, Rory Smith, Salvatore Vitale, T. J. Massinger, Jonah
Kanner, Avi Vajpeyi | Enhancing confidence in the detection of gravitational waves from
compact binaries using signal coherence | null | Phys. Rev. D 98, 042007 (2018) | 10.1103/PhysRevD.98.042007 | LIGO-P1700414 | gr-qc astro-ph.HE physics.data-an | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that gravitational-wave signals from compact binary mergers may be
better distinguished from instrumental noise transients by using Bayesian
models that look for signal coherence across a detector network. This can be
achieved even when the signal power is below the usual threshold for detection.
This method could reject the vast majority of noise transients, and therefore
increase sensitivity to weak gravitational waves. We demonstrate this using
simulated signals, as well as data for GW150914 and LVT151012. Finally, we
explore ways of incorporating our method into existing Advanced LIGO and Virgo
searches to make them significantly more powerful.
| [
{
"created": "Mon, 26 Mar 2018 18:32:05 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Aug 2018 18:11:08 GMT",
"version": "v2"
}
] | 2018-08-30 | [
[
"Isi",
"Maximiliano",
""
],
[
"Smith",
"Rory",
""
],
[
"Vitale",
"Salvatore",
""
],
[
"Massinger",
"T. J.",
""
],
[
"Kanner",
"Jonah",
""
],
[
"Vajpeyi",
"Avi",
""
]
] | We show that gravitational-wave signals from compact binary mergers may be better distinguished from instrumental noise transients by using Bayesian models that look for signal coherence across a detector network. This can be achieved even when the signal power is below the usual threshold for detection. This method could reject the vast majority of noise transients, and therefore increase sensitivity to weak gravitational waves. We demonstrate this using simulated signals, as well as data for GW150914 and LVT151012. Finally, we explore ways of incorporating our method into existing Advanced LIGO and Virgo searches to make them significantly more powerful. |
1901.02227 | Chad Hanna | Chad Hanna, Sarah Caudill, Cody Messick, Amit Reza, Surabhi Sachdev,
Leo Tsukada, Kipp Cannon, Kent Blackburn, Jolien D. E. Creighton, Heather
Fong, Patrick Godwin, Shasvath Kapadia, Tjonnie G. F. Li, Ryan Magee, Duncan
Meacher, Debnandini Mukherjee, Alex Pace, Stephen Privitera, Rico K. L. Lo,
Leslie Wade | Fast evaluation of multi-detector consistency for real-time
gravitational wave searches | null | Phys. Rev. D 101, 022003 (2020) | 10.1103/PhysRevD.101.022003 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waves searches for compact binary mergers with LIGO and Virgo
are presently a two stage process. First, a gravitational wave signal is
identified. Then, an exhaustive search over possible signal parameters is
performed. It is critical that the identification stage is efficient in order
to maximize the number of gravitational wave sources that are identified.
Initial identification of gravitational wave signals with LIGO and Virgo
happens in real-time which requires that less than one second of computational
time must be used for each one second of gravitational wave data collected. In
contrast, subsequent parameter estimation may require hundreds of hours of
computational time to analyze the same one second of gravitational wave data.
The real-time identification requirement necessitates efficient and often
approximate methods for signal analysis. We describe one piece of real-time
gravitational-wave identification: an efficient method for ascertaining a
signal's consistency between multiple gravitational wave detectors suitable for
real-time gravitational wave searches for compact binary mergers. This
technique was used in analyses of Advanced LIGO's second observing run and
Advanced Virgo's first observing run.
| [
{
"created": "Tue, 8 Jan 2019 10:02:38 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Aug 2019 13:13:46 GMT",
"version": "v2"
}
] | 2020-02-05 | [
[
"Hanna",
"Chad",
""
],
[
"Caudill",
"Sarah",
""
],
[
"Messick",
"Cody",
""
],
[
"Reza",
"Amit",
""
],
[
"Sachdev",
"Surabhi",
""
],
[
"Tsukada",
"Leo",
""
],
[
"Cannon",
"Kipp",
""
],
[
"Blackburn",... | Gravitational waves searches for compact binary mergers with LIGO and Virgo are presently a two stage process. First, a gravitational wave signal is identified. Then, an exhaustive search over possible signal parameters is performed. It is critical that the identification stage is efficient in order to maximize the number of gravitational wave sources that are identified. Initial identification of gravitational wave signals with LIGO and Virgo happens in real-time which requires that less than one second of computational time must be used for each one second of gravitational wave data collected. In contrast, subsequent parameter estimation may require hundreds of hours of computational time to analyze the same one second of gravitational wave data. The real-time identification requirement necessitates efficient and often approximate methods for signal analysis. We describe one piece of real-time gravitational-wave identification: an efficient method for ascertaining a signal's consistency between multiple gravitational wave detectors suitable for real-time gravitational wave searches for compact binary mergers. This technique was used in analyses of Advanced LIGO's second observing run and Advanced Virgo's first observing run. |
1906.00063 | Saibal Ray | Abdul Aziz, Saibal Ray, Farook Rahaman, M. Khlopov and B.K. Guha | Constraining values of bag constant for strange star candidates | 22 pages, 6 figures, 2 tables | International Journal of Modern Physics D, Vol 28 (2019),
ID-1941006 (22) | 10.1142/S0218271819410062 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a strange star model under the framework of general relativity by
using a general linear equation of state (EOS). The solution set thus obtained
is employed on altogether 20 compact star candidates to constraint values of
MIT bag model. No specific value of the bag constant ($B$) a-priori is assumed
rather possible range of values for bag constant is determined from
observational data of the said set of compact stars. To do so the
Tolman-Oppenheimer-Volkoff (TOV) equation is solved by homotopy perturbation
method (HPM) and hence we get a mass function for the stellar system. The
solution to the Einstein field equations represents a non-singular, causal and
stable stellar structure which can be related to strange stars. Eventually we
get an interesting result on the range of the bag constant as
41.58~MeV~fm$^{-3}< B <$319.31~MeV~fm$^{-3}$. We have found the maximum surface
redshift $Z^{max}_{s}=0.63$ and shown that the central redshift ($Z_c$) can not
have value larger than $2k$, where $k=2.010789 \pm 0.073203$. Also we provide a
possible value of bag constant for neutron star (NS) with quark core using
hadronic as well as quark EOS.
| [
{
"created": "Thu, 30 May 2019 07:02:03 GMT",
"version": "v1"
}
] | 2019-06-04 | [
[
"Aziz",
"Abdul",
""
],
[
"Ray",
"Saibal",
""
],
[
"Rahaman",
"Farook",
""
],
[
"Khlopov",
"M.",
""
],
[
"Guha",
"B. K.",
""
]
] | We provide a strange star model under the framework of general relativity by using a general linear equation of state (EOS). The solution set thus obtained is employed on altogether 20 compact star candidates to constraint values of MIT bag model. No specific value of the bag constant ($B$) a-priori is assumed rather possible range of values for bag constant is determined from observational data of the said set of compact stars. To do so the Tolman-Oppenheimer-Volkoff (TOV) equation is solved by homotopy perturbation method (HPM) and hence we get a mass function for the stellar system. The solution to the Einstein field equations represents a non-singular, causal and stable stellar structure which can be related to strange stars. Eventually we get an interesting result on the range of the bag constant as 41.58~MeV~fm$^{-3}< B <$319.31~MeV~fm$^{-3}$. We have found the maximum surface redshift $Z^{max}_{s}=0.63$ and shown that the central redshift ($Z_c$) can not have value larger than $2k$, where $k=2.010789 \pm 0.073203$. Also we provide a possible value of bag constant for neutron star (NS) with quark core using hadronic as well as quark EOS. |
1104.4872 | John F. Donoghue | Thibault Damour and John F. Donoghue | Spatial variation of fundamental couplings and Lunar Laser Ranging | 9 pages | null | 10.1088/0264-9381/28/16/162001 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | If the fundamental constants of nature have a cosmic spatial variation, there
will in general be extra forces with a preferred direction in space which
violate the equivalence principle. We show that the millimeter-precision Apache
Point Observatory Lunar Laser-ranging Operation provides a very sensitive probe
of such variation that has the capability of detecting a cosmic gradient of the
ratio between the quark masses and the strong interaction scale at the level
with the gradient of ln (m_quark/Lambda_QCD) ~ 2.6 x 10^-6 Glyr^-1, which is
comparable to the cosmic gradients suggested by the recently reported
measurements of Webb et al. We also point out the capability of presently
planned improved equivalence principle tests, at the Delta g/g < 10^-17 level,
to probe similar cosmic gradients.
| [
{
"created": "Tue, 26 Apr 2011 09:36:00 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Damour",
"Thibault",
""
],
[
"Donoghue",
"John F.",
""
]
] | If the fundamental constants of nature have a cosmic spatial variation, there will in general be extra forces with a preferred direction in space which violate the equivalence principle. We show that the millimeter-precision Apache Point Observatory Lunar Laser-ranging Operation provides a very sensitive probe of such variation that has the capability of detecting a cosmic gradient of the ratio between the quark masses and the strong interaction scale at the level with the gradient of ln (m_quark/Lambda_QCD) ~ 2.6 x 10^-6 Glyr^-1, which is comparable to the cosmic gradients suggested by the recently reported measurements of Webb et al. We also point out the capability of presently planned improved equivalence principle tests, at the Delta g/g < 10^-17 level, to probe similar cosmic gradients. |
0911.5195 | Vladimir Dzhunushaliev | V. Dzhunushaliev, K. Myrzakulov and R. Myrzakulov | Long-term bounce of the Universe filled with the Higgs field | new reference is added | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The cosmological solution with a long-term bouncing off time is presented.
The solution has a preceding contracting and a subsequent expanding phases and
between them there exists a bouncing off phase with arbitrary time duration.
| [
{
"created": "Fri, 27 Nov 2009 04:10:22 GMT",
"version": "v1"
},
{
"created": "Sun, 13 Dec 2009 02:56:15 GMT",
"version": "v2"
}
] | 2009-12-13 | [
[
"Dzhunushaliev",
"V.",
""
],
[
"Myrzakulov",
"K.",
""
],
[
"Myrzakulov",
"R.",
""
]
] | The cosmological solution with a long-term bouncing off time is presented. The solution has a preceding contracting and a subsequent expanding phases and between them there exists a bouncing off phase with arbitrary time duration. |
0805.0102 | Atsushi Nishizawa | Atsushi Nishizawa, Seiji Kawamura, Masa-aki Sakagami | Resonant speed meter for gravitational wave detection | 4 pages, 4 figures | Phys.Rev.Lett.101:081101,2008 | 10.1103/PhysRevLett.101.081101 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational-wave detectors have been well developed and operated with high
sensitivity. However, they still suffer from mirror displacement noise. In this
paper, we propose a resonant speed meter, as a displacement noise-canceled
configuration based on a ring-shaped synchronous recycling interferometer. The
remarkable feature of this interferometer is that, at certain frequencies,
gravitational-wave signals are amplified, while displacement noises are not.
| [
{
"created": "Thu, 1 May 2008 14:33:09 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Nishizawa",
"Atsushi",
""
],
[
"Kawamura",
"Seiji",
""
],
[
"Sakagami",
"Masa-aki",
""
]
] | Gravitational-wave detectors have been well developed and operated with high sensitivity. However, they still suffer from mirror displacement noise. In this paper, we propose a resonant speed meter, as a displacement noise-canceled configuration based on a ring-shaped synchronous recycling interferometer. The remarkable feature of this interferometer is that, at certain frequencies, gravitational-wave signals are amplified, while displacement noises are not. |
1610.04848 | Adam Levi | Adam Levi, Ehud Eilon, Amos Ori and Maarten van de Meent | Renormalized stress-energy tensor of an evaporating spinning black hole | 5 pages, 4 figures | Phys. Rev. Lett. 118, 141102 (2017) | 10.1103/PhysRevLett.118.141102 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We employ a recently developed mode-sum regularization method to compute the
renormalized stress-energy tensor of a quantum field in the Kerr background
metric (describing a stationary spinning black hole). More specifically, we
consider a minimally-coupled massless scalar field in the Unruh vacuum state,
the quantum state corresponding to an evaporating black hole. The computation
is done here for the case $a=0.7M$, using two different variants of the method:
$t$-splitting and $\varphi$-splitting, yielding good agreement between the two
(in the domain where both are applicable). We briefly discuss possible
implications of the results for computing semiclassical corrections to certain
quantities, and also for simulating dynamical evaporation of a spinning black
hole.
| [
{
"created": "Sun, 16 Oct 2016 12:37:09 GMT",
"version": "v1"
}
] | 2017-04-12 | [
[
"Levi",
"Adam",
""
],
[
"Eilon",
"Ehud",
""
],
[
"Ori",
"Amos",
""
],
[
"van de Meent",
"Maarten",
""
]
] | We employ a recently developed mode-sum regularization method to compute the renormalized stress-energy tensor of a quantum field in the Kerr background metric (describing a stationary spinning black hole). More specifically, we consider a minimally-coupled massless scalar field in the Unruh vacuum state, the quantum state corresponding to an evaporating black hole. The computation is done here for the case $a=0.7M$, using two different variants of the method: $t$-splitting and $\varphi$-splitting, yielding good agreement between the two (in the domain where both are applicable). We briefly discuss possible implications of the results for computing semiclassical corrections to certain quantities, and also for simulating dynamical evaporation of a spinning black hole. |
1109.2827 | Matteo Luca Ruggiero | Angelo Tartaglia | The Strained State Cosmology | Book chapter, to apper in "Aspects of Today's Cosmology", ISBN
978-953-307-626-3, edited by Antonio Alfonso-Faus, Intechopen 2011 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The chapter expounds a theory based on the interpretation of the dark energy
as a strain energy of a physical continuum. The theory is based on the analogy
that exists between the properties of space-time and the properties of elastic
materials, when extended to four dimensions and the Lorentzian signature. In
practice the starting point is an action integral that contains an additional
term built as elastic potential energy of strained materials is. Besides this
vacuum energy term matter/energy fields appear as usual. The strain energy term
is based on the strain tensor of empty space-time which in turn is obtained
from the non trivial part of the metric tensor. The Strained State Cosmology
(SSC) is deduced from this approach when a Robertson-Walker symmetry is
assumed: The result accounts for the accelerated expansion of the universe and
agrees with observation passing four typical cosmological tests
| [
{
"created": "Tue, 13 Sep 2011 15:27:26 GMT",
"version": "v1"
}
] | 2011-09-14 | [
[
"Tartaglia",
"Angelo",
""
]
] | The chapter expounds a theory based on the interpretation of the dark energy as a strain energy of a physical continuum. The theory is based on the analogy that exists between the properties of space-time and the properties of elastic materials, when extended to four dimensions and the Lorentzian signature. In practice the starting point is an action integral that contains an additional term built as elastic potential energy of strained materials is. Besides this vacuum energy term matter/energy fields appear as usual. The strain energy term is based on the strain tensor of empty space-time which in turn is obtained from the non trivial part of the metric tensor. The Strained State Cosmology (SSC) is deduced from this approach when a Robertson-Walker symmetry is assumed: The result accounts for the accelerated expansion of the universe and agrees with observation passing four typical cosmological tests |
0809.1693 | Felix Finster | Felix Finster and Christian Hainzl | Quantum Oscillations Can Prevent the Big Bang Singularity in an
Einstein-Dirac Cosmology | 8 pages, LaTeX, 4 figures, statement on energy conditions corrected | Found.Phys.40:116-124,2010 | 10.1007/s10701-009-9380-z | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a spatially homogeneous and isotropic system of Dirac particles
coupled to classical gravity. The dust and radiation dominated closed
Friedmann-Robertson-Walker space-times are recovered as limiting cases. We find
a mechanism where quantum oscillations of the Dirac wave functions can prevent
the formation of the big bang or big crunch singularity. Thus before the big
crunch, the collapse of the universe is stopped by quantum effects and reversed
to an expansion, so that the universe opens up entering a new era of classical
behavior.
Numerical examples of such space-times are given, and the dependence on
various parameters is discussed. Generically, one has a collapse after a finite
number of cycles. By fine-tuning the parameters we construct an example of a
space-time which is time-periodic, thus running through an infinite number of
contraction and expansion cycles.
| [
{
"created": "Wed, 10 Sep 2008 00:24:04 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Oct 2009 07:53:21 GMT",
"version": "v2"
},
{
"created": "Wed, 11 Nov 2009 15:52:38 GMT",
"version": "v3"
},
{
"created": "Mon, 10 Jan 2011 16:29:45 GMT",
"version": "v4"
}
] | 2011-07-21 | [
[
"Finster",
"Felix",
""
],
[
"Hainzl",
"Christian",
""
]
] | We consider a spatially homogeneous and isotropic system of Dirac particles coupled to classical gravity. The dust and radiation dominated closed Friedmann-Robertson-Walker space-times are recovered as limiting cases. We find a mechanism where quantum oscillations of the Dirac wave functions can prevent the formation of the big bang or big crunch singularity. Thus before the big crunch, the collapse of the universe is stopped by quantum effects and reversed to an expansion, so that the universe opens up entering a new era of classical behavior. Numerical examples of such space-times are given, and the dependence on various parameters is discussed. Generically, one has a collapse after a finite number of cycles. By fine-tuning the parameters we construct an example of a space-time which is time-periodic, thus running through an infinite number of contraction and expansion cycles. |
2109.03254 | Christopher Pope | M. Cvetic, G.W. Gibbons, C.N. Pope and B.F. Whiting | Supergravity Black Holes, Love Numbers and Harmonic Coordinates | 21 pages. Typos correct, text added | null | 10.1103/PhysRevD.105.084035 | UPR-1314-T, MI-HET-761 | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | To perform realistic tests of theories of gravity, we need to be able to look
beyond general relativity and evaluate the consistency of alternative theories
with observational data from, especially, gravitational wave detections using,
for example, an agnostic Bayesian approach. In this paper we further examine
properties of one class of such viable, alternative theories, based on metrics
arising from ungauged supergravity. In particular, we examine the massless,
neutral, minimally coupled scalar wave equation in a general stationary,
axisymmetric background metric such as that of a charged rotating black hole,
when the scalar field is either time independent or in the low-frequency,
near-zone limit, with a view to calculating the Love numbers of tidal
perturbations, and of obtaining harmonic coordinates for the background metric.
For a four-parameter family of charged asymptotically flat rotating black hole
solutions of ungauged supergravity theory known as STU black holes, which
includes Kaluza-Klein black holes and the Kerr-Sen black hole as special cases,
we find that all time-independent solutions, and hence the harmonic coordinates
of the metrics, are identical to those of the Kerr solution. In the
low-frequency limit we find the scalar fields exhibit the same $SL(2,R)$
symmetry as holds in the case of the Kerr solution. We point out extensions of
our results to a wider class of metrics, which includes solutions of
Einstein-Maxwell-Dilaton theory.
| [
{
"created": "Tue, 7 Sep 2021 18:00:04 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Sep 2021 16:07:03 GMT",
"version": "v2"
}
] | 2022-05-04 | [
[
"Cvetic",
"M.",
""
],
[
"Gibbons",
"G. W.",
""
],
[
"Pope",
"C. N.",
""
],
[
"Whiting",
"B. F.",
""
]
] | To perform realistic tests of theories of gravity, we need to be able to look beyond general relativity and evaluate the consistency of alternative theories with observational data from, especially, gravitational wave detections using, for example, an agnostic Bayesian approach. In this paper we further examine properties of one class of such viable, alternative theories, based on metrics arising from ungauged supergravity. In particular, we examine the massless, neutral, minimally coupled scalar wave equation in a general stationary, axisymmetric background metric such as that of a charged rotating black hole, when the scalar field is either time independent or in the low-frequency, near-zone limit, with a view to calculating the Love numbers of tidal perturbations, and of obtaining harmonic coordinates for the background metric. For a four-parameter family of charged asymptotically flat rotating black hole solutions of ungauged supergravity theory known as STU black holes, which includes Kaluza-Klein black holes and the Kerr-Sen black hole as special cases, we find that all time-independent solutions, and hence the harmonic coordinates of the metrics, are identical to those of the Kerr solution. In the low-frequency limit we find the scalar fields exhibit the same $SL(2,R)$ symmetry as holds in the case of the Kerr solution. We point out extensions of our results to a wider class of metrics, which includes solutions of Einstein-Maxwell-Dilaton theory. |
1903.06742 | Katerina Chatziioannou | Katerina Chatziioannou, Roberto Cotesta, Sudarshan Ghonge, Jacob
Lange, Ken K.-Y. Ng, Juan Calderon Bustillo, James Clark, Carl-Johan Haster,
Sebastian Khan, Michael Puerrer, Vivien Raymond, Salvatore Vitale, Nousha
Afshari, Stanislav Babak, Kevin Barkett, Jonathan Blackman, Alejandro Bohe,
Michael Boyle, Alessandra Buonanno, Manuela Campanelli, Gregorio Carullo,
Tony Chu, Eric Flynn, Heather Fong, Alyssa Garcia, Matthew Giesler, Maria
Haney, Mark Hannam, Ian Harry, James Healy, Daniel Hemberger, Ian Hinder,
Karan Jani, Bhavesh Khamersa, Lawrence E. Kidder, Prayush Kumar, Pablo
Laguna, Carlos O. Lousto, Geoffrey Lovelace, Tyson B. Littenberg, Lionel
London, Margaret Millhouse, Laura K. Nuttall, Frank Ohme, Richard
O'Shaughnessy, Serguei Ossokine, Francesco Pannarale, Patricia Schmidt,
Harald P. Pfeiffer, Mark A. Scheel, Lijing Shao, Deirdre Shoemaker, Bela
Szilagyi, Andrea Taracchini, Saul A. Teukolsky, Yosef Zlochower | On the properties of the massive binary black hole merger GW170729 | 14 pages, 8 figures, final published version, samples available at
https://git.ligo.org/katerina.chatziioannou/gw170729hm_datarelease | Phys. Rev. D 100, 104015 (2019) | 10.1103/PhysRevD.100.104015 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a detailed investigation into the properties of GW170729, the
gravitational wave with the most massive and distant source confirmed to date.
We employ an extensive set of waveform models, including new improved models
that incorporate the effect of higher-order waveform modes which are
particularly important for massive systems. We find no indication of
spin-precession, but the inclusion of higher-order modes in the models results
in an improved estimate for the mass ratio of $(0.3-0.8)$ at the 90\% credible
level. Our updated measurement excludes equal masses at that level. We also
find that models with higher-order modes lead to the data being more consistent
with a smaller effective spin, with the probability that the effective spin is
greater than zero being reduced from $99\%$ to $94\%$. The 90\% credible
interval for the effective spin parameter is now $(-0.01-0.50)$. Additionally,
the recovered signal-to-noise ratio increases by $\sim0.3$ units compared to
analyses without higher-order modes. We study the effect of common spin priors
on the derived spin and mass measurements, and observe small shifts in the
spins, while the masses remain unaffected. We argue that our conclusions are
robust against systematic errors in the waveform models. We also compare the
above waveform-based analysis which employs compact-binary waveform models to a
more flexible wavelet- and chirplet-based analysis. We find consistency between
the two, with overlaps of $\sim 0.9$, typical of what is expected from
simulations of signals similar to GW170729, confirming that the data are
well-described by the existing waveform models. Finally, we study the
possibility that the primary component of GW170729 was the remnant of a past
merger of two black holes and find this scenario to be indistinguishable from
the standard formation scenario.
| [
{
"created": "Fri, 15 Mar 2019 18:42:09 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Mar 2019 12:22:27 GMT",
"version": "v2"
},
{
"created": "Fri, 8 Nov 2019 02:13:25 GMT",
"version": "v3"
}
] | 2019-11-13 | [
[
"Chatziioannou",
"Katerina",
""
],
[
"Cotesta",
"Roberto",
""
],
[
"Ghonge",
"Sudarshan",
""
],
[
"Lange",
"Jacob",
""
],
[
"Ng",
"Ken K. -Y.",
""
],
[
"Bustillo",
"Juan Calderon",
""
],
[
"Clark",
"James",
... | We present a detailed investigation into the properties of GW170729, the gravitational wave with the most massive and distant source confirmed to date. We employ an extensive set of waveform models, including new improved models that incorporate the effect of higher-order waveform modes which are particularly important for massive systems. We find no indication of spin-precession, but the inclusion of higher-order modes in the models results in an improved estimate for the mass ratio of $(0.3-0.8)$ at the 90\% credible level. Our updated measurement excludes equal masses at that level. We also find that models with higher-order modes lead to the data being more consistent with a smaller effective spin, with the probability that the effective spin is greater than zero being reduced from $99\%$ to $94\%$. The 90\% credible interval for the effective spin parameter is now $(-0.01-0.50)$. Additionally, the recovered signal-to-noise ratio increases by $\sim0.3$ units compared to analyses without higher-order modes. We study the effect of common spin priors on the derived spin and mass measurements, and observe small shifts in the spins, while the masses remain unaffected. We argue that our conclusions are robust against systematic errors in the waveform models. We also compare the above waveform-based analysis which employs compact-binary waveform models to a more flexible wavelet- and chirplet-based analysis. We find consistency between the two, with overlaps of $\sim 0.9$, typical of what is expected from simulations of signals similar to GW170729, confirming that the data are well-described by the existing waveform models. Finally, we study the possibility that the primary component of GW170729 was the remnant of a past merger of two black holes and find this scenario to be indistinguishable from the standard formation scenario. |
2212.03042 | Dipanjan Dey | Ashok B. Joshi, Divya Tahelyani, Dipanjan Dey, and Pankaj S. Joshi | Observational aspects of a class of Dark matter spacetimes | 16 pages, 8 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Various astrophysical and cosmological observations today serve as an
indirect evidence of the existence of dark matter in the universe. In the
present work, we propose a class of spacetimes that show some important
characteristics relevant to the spacetime of a dark matter halo. These
spacetimes are static and spherically symmetric solutions of the Einstein field
equations. The proposed spacetimes satisfy the flat velocity profile of a
galactic object far away from the center, they give good agreement to the
astrometric data of the S2 star, and these also cast a central shadow. Using
the Penrose diagram, we show that the causal nature of the central singularity
here is null. This single spacetime model for galactic dark matter may
therefore be used to explain some of the properties of galactic dynamics at
different length scales.
| [
{
"created": "Tue, 6 Dec 2022 15:18:31 GMT",
"version": "v1"
}
] | 2022-12-07 | [
[
"Joshi",
"Ashok B.",
""
],
[
"Tahelyani",
"Divya",
""
],
[
"Dey",
"Dipanjan",
""
],
[
"Joshi",
"Pankaj S.",
""
]
] | Various astrophysical and cosmological observations today serve as an indirect evidence of the existence of dark matter in the universe. In the present work, we propose a class of spacetimes that show some important characteristics relevant to the spacetime of a dark matter halo. These spacetimes are static and spherically symmetric solutions of the Einstein field equations. The proposed spacetimes satisfy the flat velocity profile of a galactic object far away from the center, they give good agreement to the astrometric data of the S2 star, and these also cast a central shadow. Using the Penrose diagram, we show that the causal nature of the central singularity here is null. This single spacetime model for galactic dark matter may therefore be used to explain some of the properties of galactic dynamics at different length scales. |
1710.05837 | LSC P&P Committee | The LIGO Scientific Collaboration and the Virgo Collaboration: B. P.
Abbott, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, C. Adams, T. Adams,
P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Afrough, B. Agarwal,
M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P.
Ajith, B. Allen, G. Allen, A. Allocca, P. A. Altin, A. Amato, A. Ananyeva, S.
B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai,
M. C. Araya, J. S. Areeda, N. Arnaud, K. G. Arun, S. Ascenzi, G. Ashton, M.
Ast, S. M. Aston, P. Astone, D. V. Atallah, P. Aufmuth, C. Aulbert, K.
AultONeal, C. Austin, A. Avila-Alvarez, S. Babak, P. Bacon, M. K. M. Bader,
S. Bae, P. T. Baker, F. Baldaccini, G. Ballardin, S. W. Ballmer, S. Banagiri,
J. C. Barayoga, S. E. Barclay, B. C. Barish, D. Barker, K. Barkett, F.
Barone, B. Barr, L. Barsotti, M. Barsuglia, D. Barta, J. Bartlett, I. Bartos,
R. Bassiri, A. Basti, J. C. Batch, M. Bawaj, J. C. Bayley, M. Bazzan, B.
B'ecsy, C. Beer, M. Bejger, I. Belahcene, A. S. Bell, B. K. Berger, G.
Bergmann, J. J. Bero, C. P. L. Berry, D. Bersanetti, A. Bertolini, J.
Betzwieser, S. Bhagwat, R. Bhandare, I. A. Bilenko, G. Billingsley, C. R.
Billman, J. Birch, R. Birney, O. Birnholtz, S. Biscans, S. Biscoveanu, A.
Bisht, M. Bitossi, C. Biwer, M. A. Bizouard, J. K. Blackburn, J. Blackman, C.
D. Blair, D. G. Blair, R. M. Blair, S. Bloemen, O. Bock, N. Bode, M. Boer, G.
Bogaert, A. Bohe, F. Bondu, E. Bonilla, R. Bonnand, B. A. Boom, R. Bork, V.
Boschi, S. Bose, K. Bossie, Y. Bouffanais, A. Bozzi, C. Bradaschia, P. R.
Brady, M. Branchesi, J. E. Brau, T. Briant, A. Brillet, M. Brinkmann, V.
Brisson, P. Brockill, J. E. Broida, A. F. Brooks, D. A. Brown, D. D. Brown,
S. Brunett, C. C. Buchanan, A. Buikema, T. Bulik, H. J. Bulten, A. Buonanno,
D. Buskulic, C. Buy, R. L. Byer, M. Cabero, L. Cadonati, G. Cagnoli, C.
Cahillane, J. Calder'on Bustillo, T. A. Callister, E. Calloni, J. B. Camp, M.
Canepa, P. Canizares, K. C. Cannon, H. Cao, J. Cao, C. D. Capano, E.
Capocasa, F. Carbognani, S. Caride, M. F. Carney, J. Casanueva Diaz, C.
Casentini, S. Caudill, M. Cavagli`a, F. Cavalier, R. Cavalieri, G. Cella, C.
B. Cepeda, P. Cerd'a-Dur'an, G. Cerretani, E. Cesarini, S. J. Chamberlin, M.
Chan, S. Chao, P. Charlton, E. Chase, E. Chassande-Mottin, D. Chatterjee, B.
D. Cheeseboro, H. Y. Chen, X. Chen, Y. Chen, H.-P. Cheng, H. Chia, A.
Chincarini, A. Chiummo, T. Chmiel, H. S. Cho, M. Cho, J. H. Chow, N.
Christensen, Q. Chu, A. J. K. Chua, S. Chua, A. K. W. Chung, S. Chung, G.
Ciani, R. Ciolfi, C. E. Cirelli, A. Cirone, F. Clara, J. A. Clark, P.
Clearwater, F. Cleva, C. Cocchieri, E. Coccia, P.-F. Cohadon, D. Cohen, A.
Colla, C. G. Collette, L. R. Cominsky, M. Constancio Jr., L. Conti, S. J.
Cooper, P. Corban, T. R. Corbitt, I. Cordero-Carri'on, K. R. Corley, N.
Cornish, A. Corsi, S. Cortese, C. A. Costa, M. W. Coughlin, S. B. Coughlin,
J.-P. Coulon, S. T. Countryman, P. Couvares, P. B. Covas, E. E. Cowan, D. M.
Coward, M. J. Cowart, D. C. Coyne, R. Coyne, J. D. E. Creighton, T. D.
Creighton, J. Cripe, S. G. Crowder, T. J. Cullen, A. Cumming, L. Cunningham,
E. Cuoco, T. Dal Canton, G. D'alya, S. L. Danilishin, S. D'Antonio, K.
Danzmann, A. Dasgupta, C. F. Da Silva Costa, V. Dattilo, I. Dave, M. Davier,
D. Davis, E. J. Daw, B. Day, S. De, D. DeBra, J. Degallaix, M. De Laurentis,
S. Del'eglise, W. Del Pozzo, N. Demos, T. Denker, T. Dent, R. De Pietri, V.
Dergachev, R. De Rosa, R. T. DeRosa, C. De Rossi, R. DeSalvo, O. de Varona,
J. Devenson, S. Dhurandhar, M. C. D'iaz, L. Di Fiore, M. Di Giovanni, T. Di
Girolamo, A. Di Lieto, S. Di Pace, I. Di Palma, F. Di Renzo, Z. Doctor, V.
Dolique, F. Donovan, K. L. Dooley, S. Doravari, I. Dorrington, R. Douglas, M.
Dovale 'Alvarez, T. P. Downes, M. Drago, C. Dreissigacker, J. C. Driggers, Z.
Du, M. Ducrot, P. Dupej, S. E. Dwyer, T. B. Edo, M. C. Edwards, A. Effler,
H.-B. Eggenstein, P. Ehrens, J. Eichholz, S. S. Eikenberry, R. A. Eisenstein,
R. C. Essick, D. Estevez, Z. B. Etienne, T. Etzel, M. Evans, T. M. Evans, M.
Factourovich, V. Fafone, H. Fair, S. Fairhurst, X. Fan, S. Farinon, B. Farr,
W. M. Farr, E. J. Fauchon-Jones, M. Favata, M. Fays, C. Fee, H. Fehrmann, J.
Feicht, M. M. Fejer, A. Fernandez-Galiana, I. Ferrante, E. C. Ferreira, F.
Ferrini, F. Fidecaro, D. Finstad, I. Fiori, D. Fiorucci, M. Fishbach, R. P.
Fisher, M. Fitz-Axen, R. Flaminio, M. Fletcher, H. Fong, J. A. Font, P. W. F.
Forsyth, S. S. Forsyth, J.-D. Fournier, S. Frasca, F. Frasconi, Z. Frei, A.
Freise, R. Frey, V. Frey, E. M. Fries, P. Fritschel, V. V. Frolov, P. Fulda,
M. Fyffe, H. Gabbard, B. U. Gadre, S. M. Gaebel, J. R. Gair, L. Gammaitoni,
M. R. Ganija, S. G. Gaonkar, C. Garcia-Quiros, F. Garufi, B. Gateley, S.
Gaudio, G. Gaur, V. Gayathri, N. Gehrels, G. Gemme, E. Genin, A. Gennai, D.
George, J. George, L. Gergely, V. Germain, S. Ghonge, Abhirup Ghosh,
Archisman Ghosh, S. Ghosh, J. A. Giaime, K. D. Giardina, A. Giazotto, K.
Gill, L. Glover, E. Goetz, R. Goetz, S. Gomes, B. Goncharov, G. Gonz'alez, J.
M. Gonzalez Castro, A. Gopakumar, M. L. Gorodetsky, S. E. Gossan, M.
Gosselin, R. Gouaty, A. Grado, C. Graef, M. Granata, A. Grant, S. Gras, C.
Gray, G. Greco, A. C. Green, E. M. Gretarsson, P. Groot, H. Grote, S.
Grunewald, P. Gruning, G. M. Guidi, X. Guo, A. Gupta, M. K. Gupta, K. E.
Gushwa, E. K. Gustafson, R. Gustafson, O. Halim, B. R. Hall, E. D. Hall, E.
Z. Hamilton, G. Hammond, M. Haney, M. M. Hanke, J. Hanks, C. Hanna, M. D.
Hannam, O. A. Hannuksela, J. Hanson, T. Hardwick, J. Harms, G. M. Harry, I.
W. Harry, M. J. Hart, C.-J. Haster, K. Haughian, J. Healy, A. Heidmann, M. C.
Heintze, H. Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, J. Hennig,
A. W. Heptonstall, M. Heurs, S. Hild, T. Hinderer, D. Hoak, D. Hofman, K.
Holt, D. E. Holz, P. Hopkins, C. Horst, J. Hough, E. A. Houston, E. J.
Howell, A. Hreibi, Y. M. Hu, E. A. Huerta, D. Huet, B. Hughey, S. Husa, S. H.
Huttner, T. Huynh-Dinh, N. Indik, R. Inta, G. Intini, H. N. Isa, J.-M. Isac,
M. Isi, B. R. Iyer, K. Izumi, T. Jacqmin, K. Jani, P. Jaranowski, S. Jawahar,
F. Jim'enez-Forteza, W. W. Johnson, D. I. 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, S. Karki, K. S. Karvinen, M. Kasprzack, M.
Katolik, E. Katsavounidis, W. Katzman, S. Kaufer, K. Kawabe, F. K'ef'elian,
D. Keitel, A. J. Kemball, R. Kennedy, C. Kent, J. S. Key, F. Y. Khalili, I.
Khan, S. Khan, Z. Khan, E. A. Khazanov, N. Kijbunchoo, Chunglee Kim, J. C.
Kim, K. Kim, W. Kim, W. S. Kim, Y.-M. Kim, S. J. Kimbrell, E. J. King, P. J.
King, M. Kinley-Hanlon, R. Kirchhoff, J. S. Kissel, L. Kleybolte, S.
Klimenko, T. D. Knowles, P. Koch, S. M. Koehlenbeck, S. Koley, V. Kondrashov,
A. Kontos, M. Korobko, W. Z. Korth, I. Kowalska, D. B. Kozak, C. Kr"amer, V.
Kringel, B. Krishnan, A. Kr'olak, G. Kuehn, P. Kumar, R. Kumar, S. Kumar, L.
Kuo, A. Kutynia, S. Kwang, B. D. Lackey, K. H. Lai, M. Landry, R. N. Lang, J.
Lange, B. Lantz, R. K. Lanza, A. Lartaux-Vollard, P. D. Lasky, M. Laxen, A.
Lazzarini, C. Lazzaro, P. Leaci, S. Leavey, C. H. Lee, H. K. Lee, H. M. Lee,
H. W. Lee, K. Lee, J. Lehmann, A. Lenon, M. Leonardi, N. Leroy, N. Letendre,
Y. Levin, T. G. F. Li, S. D. Linker, T. B. Littenberg, J. Liu, R. K. L. Lo,
N. A. Lockerbie, L. T. London, J. E. Lord, M. Lorenzini, V. Loriette, M.
Lormand, G. Losurdo, J. D. Lough, C. O. Lousto, G. Lovelace, H. L"uck, D.
Lumaca, A. P. Lundgren, R. Lynch, Y. Ma, R. Macas, S. Macfoy, B.
Machenschalk, M. MacInnis, D. M. Macleod, I. Maga\~na Hernandez, F.
Maga\~na-Sandoval, L. Maga\~na Zertuche, R. M. Magee, E. Majorana, I.
Maksimovic, N. Man, V. Mandic, V. Mangano, G. L. Mansell, M. Manske, M.
Mantovani, F. Marchesoni, F. Marion, S. M'arka, Z. M'arka, C. Markakis, A. S.
Markosyan, A. Markowitz, E. Maros, A. Marquina, F. Martelli, L. Martellini,
I. W. Martin, R. M. Martin, D. V. Martynov, K. Mason, E. Massera, A.
Masserot, T. J. Massinger, M. Masso-Reid, S. Mastrogiovanni, A. Matas, F.
Matichard, L. Matone, N. Mavalvala, N. Mazumder, R. McCarthy, D. E.
McClelland, S. McCormick, L. McCuller, S. C. McGuire, G. McIntyre, J. McIver,
D. J. McManus, L. McNeill, T. McRae, S. T. McWilliams, D. Meacher, G. D.
Meadors, M. Mehmet, J. Meidam, E. Mejuto-Villa, A. Melatos, G. Mendell, R. A.
Mercer, E. L. Merilh, M. Merzougui, S. Meshkov, C. Messenger, C. Messick, R.
Metzdorff, P. M. Meyers, H. Miao, C. Michel, H. Middleton, E. E. Mikhailov,
L. Milano, A. L. Miller, B. B. Miller, J. Miller, M. Millhouse, M. C.
Milovich-Goff, O. Minazzoli, Y. Minenkov, J. Ming, C. Mishra, S. Mitra, V. P.
Mitrofanov, G. Mitselmakher, R. Mittleman, D. Moffa, A. Moggi, K. Mogushi, M.
Mohan, S. R. P. Mohapatra, M. Montani, C. J. Moore, D. Moraru, G. Moreno, S.
R. Morriss, B. Mours, C. M. Mow-Lowry, G. Mueller, A. W. Muir, Arunava
Mukherjee, D. Mukherjee, S. Mukherjee, N. Mukund, A. Mullavey, J. Munch, E.
A. Mu\~niz, M. Muratore, P. G. Murray, K. Napier, I. Nardecchia, L.
Naticchioni, R. K. Nayak, J. Neilson, G. Nelemans, T. J. N. Nelson, M. Nery,
A. Neunzert, L. Nevin, J. M. Newport, G. Newton, K. K. Y. Ng, T. T. Nguyen,
D. Nichols, A. B. Nielsen, S. Nissanke, A. Nitz, A. Noack, F. Nocera, D.
Nolting, C. North, L. K. Nuttall, J. Oberling, G. D. O'Dea, G. H. Ogin, J. J.
Oh, S. H. Oh, F. Ohme, M. A. Okada, M. Oliver, P. Oppermann, Richard J. Oram,
B. O'Reilly, R. Ormiston, L. F. Ortega, R. O'Shaughnessy, S. Ossokine, D. J.
Ottaway, H. Overmier, B. J. Owen, A. E. Pace, J. Page, M. A. Page, A. Pai, S.
A. Pai, J. R. Palamos, O. Palashov, C. Palomba, A. Pal-Singh, Howard Pan,
Huang-Wei Pan, B. Pang, P. T. H. Pang, C. Pankow, F. Pannarale, B. C. Pant,
F. Paoletti, A. Paoli, M. A. Papa, A. Parida, W. Parker, D. Pascucci, A.
Pasqualetti, R. Passaquieti, D. Passuello, M. Patil, B. Patricelli, B. L.
Pearlstone, M. Pedraza, R. Pedurand, L. Pekowsky, A. Pele, S. Penn, C. J.
Perez, A. Perreca, L. M. Perri, H. P. Pfeiffer, M. Phelps, O. J. Piccinni, M.
Pichot, F. Piergiovanni, V. Pierro, G. Pillant, L. Pinard, I. M. Pinto, M.
Pirello, M. Pitkin, M. Poe, R. Poggiani, P. Popolizio, E. K. Porter, A. Post,
J. Powell, J. Prasad, J. W. W. Pratt, G. Pratten, V. Predoi, T. Prestegard,
M. Prijatelj, M. Principe, S. Privitera, G. A. Prodi, L. G. Prokhorov, O.
Puncken, M. Punturo, P. Puppo, M. P"urrer, H. Qi, V. Quetschke, E. A.
Quintero, R. Quitzow-James, F. J. Raab, D. S. Rabeling, H. Radkins, P.
Raffai, S. Raja, C. Rajan, B. Rajbhandari, M. Rakhmanov, K. E. Ramirez, A.
Ramos-Buades, P. Rapagnani, V. Raymond, M. Razzano, J. Read, T. Regimbau, L.
Rei, S. Reid, D. H. Reitze, W. Ren, S. D. Reyes, F. Ricci, P. M. Ricker, S.
Rieger, K. Riles, M. Rizzo, N. A. Robertson, R. Robie, F. Robinet, A. Rocchi,
L. Rolland, J. G. Rollins, V. J. Roma, J. D. Romano, R. Romano, C. L. Romel,
J. H. Romie, D. Rosi'nska, M. P. Ross, S. Rowan, A. R"udiger, P. Ruggi, G.
Rutins, K. Ryan, S. Sachdev, T. Sadecki, L. Sadeghian, M. Sakellariadou, L.
Salconi, M. Saleem, F. Salemi, A. Samajdar, L. Sammut, L. M. Sampson, E. J.
Sanchez, L. E. Sanchez, N. Sanchis-Gual, V. Sandberg, J. R. Sanders, B.
Sassolas, B. S. Sathyaprakash, P. R. Saulson, O. Sauter, R. L. Savage, A.
Sawadsky, P. Schale, M. Scheel, J. Scheuer, J. Schmidt, P. Schmidt, R.
Schnabel, R. M. S. Schofield, A. Sch"onbeck, E. Schreiber, D. Schuette, B. W.
Schulte, B. F. Schutz, S. G. Schwalbe, J. Scott, S. M. Scott, E. Seidel, D.
Sellers, A. S. Sengupta, D. Sentenac, V. Sequino, A. Sergeev, D. A. Shaddock,
T. J. Shaffer, A. A. Shah, M. S. Shahriar, M. B. Shaner, L. Shao, B. Shapiro,
P. Shawhan, A. Sheperd, D. H. Shoemaker, D. M. Shoemaker, K. Siellez, X.
Siemens, M. Sieniawska, D. Sigg, A. D. Silva, L. P. Singer, A. Singh, A.
Singhal, A. M. Sintes, B. J. J. Slagmolen, B. Smith, J. R. Smith, R. J. E.
Smith, S. Somala, E. J. Son, J. A. Sonnenberg, B. Sorazu, F. Sorrentino, T.
Souradeep, A. P. Spencer, A. K. Srivastava, K. Staats, A. Staley, M. Steinke,
J. Steinlechner, S. Steinlechner, D. Steinmeyer, S. P. Stevenson, R. Stone,
D. J. Stops, K. A. Strain, G. Stratta, S. E. Strigin, A. Strunk, R. Sturani,
A. L. Stuver, T. Z. Summerscales, L. Sun, S. Sunil, J. Suresh, P. J. Sutton,
B. L. Swinkels, M. J. Szczepa'nczyk, M. Tacca, S. C. Tait, C. Talbot, D.
Talukder, D. B. Tanner, M. T'apai, A. Taracchini, J. D. Tasson, J. A. Taylor,
R. Taylor, S. V. Tewari, T. Theeg, F. Thies, E. G. Thomas, M. Thomas, P.
Thomas, K. A. Thorne, E. Thrane, S. Tiwari, V. Tiwari, K. V. Tokmakov, K.
Toland, M. Tonelli, Z. Tornasi, A. Torres-Forn'e, C. I. Torrie, D. T"oyr"a,
F. Travasso, G. Traylor, J. Trinastic, M. C. Tringali, L. Trozzo, K. W.
Tsang, M. Tse, R. Tso, L. Tsukada, D. Tsuna, D. Tuyenbayev, K. Ueno, D.
Ugolini, C. S. Unnikrishnan, A. L. Urban, S. A. Usman, H. Vahlbruch, G.
Vajente, G. Valdes, 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,
A. A. van Veggel, M. Vardaro, V. Varma, S. Vass, M. Vas'uth, A. Vecchio, G.
Vedovato, J. Veitch, P. J. Veitch, K. Venkateswara, G. Venugopalan, D.
Verkindt, F. Vetrano, A. Vicer'e, A. D. Viets, S. Vinciguerra, D. J. Vine,
J.-Y. Vinet, S. Vitale, T. Vo, H. Vocca, C. Vorvick, S. P. Vyatchanin, A. R.
Wade, L. E. Wade, M. Wade, R. Walet, M. Walker, L. Wallace, S. Walsh, G.
Wang, H. Wang, J. Z. Wang, W. H. Wang, Y. F. Wang, R. L. Ward, J. Warner, M.
Was, J. Watchi, B. Weaver, L.-W. Wei, M. Weinert, A. J. Weinstein, R. Weiss,
L. Wen, E. K. Wessel, P. Wessels, J. Westerweck, T. Westphal, K. Wette, J. T.
Whelan, B. F. Whiting, C. Whittle, D. Wilken, D. Williams, R. D. Williams, A.
R. Williamson, J. L. Willis, B. Willke, M. H. Wimmer, W. Winkler, C. C. Wipf,
H. Wittel, G. Woan, J. Woehler, J. Wofford, K. W. K. Wong, J. Worden, J. L.
Wright, D. S. Wu, D. M. Wysocki, S. Xiao, H. Yamamoto, C. C. Yancey, L. Yang,
M. J. Yap, M. Yazback, Hang Yu, Haocun Yu, M. Yvert, A. Zadro.zny, M.
Zanolin, T. Zelenova, J.-P. Zendri, M. Zevin, L. Zhang, M. Zhang, T. Zhang,
Y.-H. Zhang, C. Zhao, M. Zhou, Z. Zhou, S. J. Zhu, X. J. Zhu, M. E. Zucker,
J. Zweizig | GW170817: Implications for the Stochastic Gravitational-Wave Background
from Compact Binary Coalescences | 12 pages, 3 figures | Phys. Rev. Lett. 120, 091101 (2018) | 10.1103/PhysRevLett.120.091101 | LIGO P1700272 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The LIGO Scientific and Virgo Collaborations have announced the first
detection of gravitational waves from the coalescence of two neutron stars. The
merger rate of binary neutron stars estimated from this event suggests that
distant, unresolvable binary neutron stars create a significant astrophysical
stochastic gravitational-wave background. The binary neutron star background
will add to the background from binary black holes, increasing the amplitude of
the total astrophysical background relative to previous expectations. In the
Advanced LIGO-Virgo frequency band most sensitive to stochastic backgrounds
(near 25 Hz), we predict a total astrophysical background with amplitude
$\Omega_{\rm GW} (f=25 \text{Hz}) = 1.8_{-1.3}^{+2.7} \times 10^{-9}$ with
$90\%$ confidence, compared with $\Omega_{\rm GW} (f=25 \text{Hz}) =
1.1_{-0.7}^{+1.2} \times 10^{-9}$ from binary black holes alone. Assuming the
most probable rate for compact binary mergers, we find that the total
background may be detectable with a signal-to-noise-ratio of 3 after 40 months
of total observation time, based on the expected timeline for Advanced LIGO and
Virgo to reach their design sensitivity.
| [
{
"created": "Mon, 16 Oct 2017 16:57:22 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Sep 2019 22:04:18 GMT",
"version": "v2"
}
] | 2019-10-02 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"Abbott",
"B. P.",
""
],
[
"Abbott",
"R.",
""
],
[
"Abbott",
"T. D.",
""
],
[
"Acernese",
"F.",
""
],
[
"Ackley",
"K.",
... | The LIGO Scientific and Virgo Collaborations have announced the first detection of gravitational waves from the coalescence of two neutron stars. The merger rate of binary neutron stars estimated from this event suggests that distant, unresolvable binary neutron stars create a significant astrophysical stochastic gravitational-wave background. The binary neutron star background will add to the background from binary black holes, increasing the amplitude of the total astrophysical background relative to previous expectations. In the Advanced LIGO-Virgo frequency band most sensitive to stochastic backgrounds (near 25 Hz), we predict a total astrophysical background with amplitude $\Omega_{\rm GW} (f=25 \text{Hz}) = 1.8_{-1.3}^{+2.7} \times 10^{-9}$ with $90\%$ confidence, compared with $\Omega_{\rm GW} (f=25 \text{Hz}) = 1.1_{-0.7}^{+1.2} \times 10^{-9}$ from binary black holes alone. Assuming the most probable rate for compact binary mergers, we find that the total background may be detectable with a signal-to-noise-ratio of 3 after 40 months of total observation time, based on the expected timeline for Advanced LIGO and Virgo to reach their design sensitivity. |
2105.00736 | Albert Huber | Albert Huber | Hidden Killing Fields, Geometric Symmetries and Black Hole Mergers | 22 pages, 1 figure; section one extended, results unchanged; matches
published version | Ann. Phys. 2021-10 | 10.1016/j.aop.2021.168650 | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | In the present work, using the recently introduced framework of local
geometric deformations, special types of vector fields - so-called hidden
Killing vector fields - are constructed, which solve the Killing equation not
globally, but only locally, i.e. in local subregions of spacetime. Taking
advantage of the fact that the vector fields coincide locally with Killing
fields and therefore allow the consideration of integral laws that convert into
exact physical conservation laws on local scales, balance laws in dynamical
systems without global Killing symmetries are derived that mimic as closely as
possible the conservation laws for energy and angular momentum of highly
symmetric models. The utility of said balance laws is demonstrated by a
concrete geometric example, namely a toy model for the binary merger of two
extremal Reissner-Nordstr\"om black holes.
| [
{
"created": "Mon, 3 May 2021 10:27:24 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Oct 2021 07:57:54 GMT",
"version": "v2"
}
] | 2021-10-15 | [
[
"Huber",
"Albert",
""
]
] | In the present work, using the recently introduced framework of local geometric deformations, special types of vector fields - so-called hidden Killing vector fields - are constructed, which solve the Killing equation not globally, but only locally, i.e. in local subregions of spacetime. Taking advantage of the fact that the vector fields coincide locally with Killing fields and therefore allow the consideration of integral laws that convert into exact physical conservation laws on local scales, balance laws in dynamical systems without global Killing symmetries are derived that mimic as closely as possible the conservation laws for energy and angular momentum of highly symmetric models. The utility of said balance laws is demonstrated by a concrete geometric example, namely a toy model for the binary merger of two extremal Reissner-Nordstr\"om black holes. |
gr-qc/9409043 | Matt Visser | Matt Visser | Scale anomalies imply violation of the averaged null energy condition | 6 pages; ReV_TeX 3.0] | Phys.Lett. B349 (1995) 443-447 | 10.1016/0370-2693(95)00303-3 | null | gr-qc hep-th | null | Considerable interest has recently been expressed regarding the issue of
whether or not quantum field theory on a fixed but curved background spacetime
satisfies the averaged null energy condition (ANEC). A comment by Wald and
Yurtsever [Phys. Rev. D43, 403 (1991)] indicates that in general the answer is
no. In this note I explore this issue in more detail, and succeed in
characterizing a broad class of spacetimes in which the ANEC is guaranteed to
be violated. Finally, I add some comments regarding ANEC violation in
Schwarzschild spacetime.
| [
{
"created": "Tue, 20 Sep 1994 19:50:35 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Visser",
"Matt",
""
]
] | Considerable interest has recently been expressed regarding the issue of whether or not quantum field theory on a fixed but curved background spacetime satisfies the averaged null energy condition (ANEC). A comment by Wald and Yurtsever [Phys. Rev. D43, 403 (1991)] indicates that in general the answer is no. In this note I explore this issue in more detail, and succeed in characterizing a broad class of spacetimes in which the ANEC is guaranteed to be violated. Finally, I add some comments regarding ANEC violation in Schwarzschild spacetime. |
gr-qc/0010105 | Michael B. Mensky | Michael B. Mensky | Classical and quantum equivalence principle in terms of the path group | LATEX, 5 pages | Helv.Phys.Acta 69:301-304,1996 | null | null | gr-qc | null | A natural mapping of paths in a curved space onto the paths in the
corresponding (tangent) flat space may be used to reduce the curved-space-time
path integral to the flat-space-time path integral. The dynamics of the
particle in a curved space-time is expressed then in terms of an integral over
paths in the flat (Minkowski) space-time. This may be called quantum
equivalence principle. Contrary to the known DeWitt's definition of a
curved-space path integral, the present definition leads to the covariant
equation of motion without a scalar curvature term. The reduction of a
curved-space path integral to the flat-space path integral may be expressed in
terms of a representation of the path group. With the help of this
representation all the results may be generalized to the case of an arbitrary
external field.
| [
{
"created": "Sat, 28 Oct 2000 12:43:54 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Nov 2000 15:01:56 GMT",
"version": "v2"
}
] | 2011-04-15 | [
[
"Mensky",
"Michael B.",
""
]
] | A natural mapping of paths in a curved space onto the paths in the corresponding (tangent) flat space may be used to reduce the curved-space-time path integral to the flat-space-time path integral. The dynamics of the particle in a curved space-time is expressed then in terms of an integral over paths in the flat (Minkowski) space-time. This may be called quantum equivalence principle. Contrary to the known DeWitt's definition of a curved-space path integral, the present definition leads to the covariant equation of motion without a scalar curvature term. The reduction of a curved-space path integral to the flat-space path integral may be expressed in terms of a representation of the path group. With the help of this representation all the results may be generalized to the case of an arbitrary external field. |
gr-qc/9806046 | Vladimir Dzhunushaliev | Dzhunushaliev V.D | Spherically Symmetric Solution for Torsion and the Dirac equation in 5D
spacetime | 7 pages, REVTEX, essential changing of text | Int.J.Mod.Phys.D7:909-915,1998 | 10.1142/S0218271898000590 | null | gr-qc hep-th | null | Torsion in a 5D spacetime is considered. In this case gravitation is defined
by the 5D metric and the torsion. It is conjectured that torsion is connected
with a spinor field. In this case Dirac's equation becomes the nonlinear
Heisenberg equation. It is shown that this equation has a discrete spectrum of
solutions with each solution being regular on the whole space and having finite
energy. Every solution is concentrated on the Planck region and hence we can
say that torsion should play an important role in quantum gravity in the
formation of bubbles of spacetime foam. On the basis of the algebraic relation
between torsion and the classical spinor field in Einstein-Cartan gravity the
geometrical interpretation of the spinor field is considered as ``the square
root'' of torsion.
| [
{
"created": "Tue, 9 Jun 1998 14:23:23 GMT",
"version": "v1"
},
{
"created": "Tue, 21 Jul 1998 13:03:27 GMT",
"version": "v2"
}
] | 2010-11-19 | [
[
"D",
"Dzhunushaliev V.",
""
]
] | Torsion in a 5D spacetime is considered. In this case gravitation is defined by the 5D metric and the torsion. It is conjectured that torsion is connected with a spinor field. In this case Dirac's equation becomes the nonlinear Heisenberg equation. It is shown that this equation has a discrete spectrum of solutions with each solution being regular on the whole space and having finite energy. Every solution is concentrated on the Planck region and hence we can say that torsion should play an important role in quantum gravity in the formation of bubbles of spacetime foam. On the basis of the algebraic relation between torsion and the classical spinor field in Einstein-Cartan gravity the geometrical interpretation of the spinor field is considered as ``the square root'' of torsion. |
0804.4296 | Bojan Losic | B. Losic and W.G. Unruh | Cosmological Perturbation Theory in Slow-Roll Spacetimes | Version accepted by PRL (however, with correct non PRL format for
arxiv posting). Clarified and expanded | Phys.Rev.Lett.101:111101,2008 | 10.1103/PhysRevLett.101.111101 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a gauge invariant argument that a nonlocal measure of second-order
metric and matter perturbations dominate that of linear fluctuations in its
effect on the gravitational field in 'slow-rolling' spacetimes.
| [
{
"created": "Sun, 27 Apr 2008 20:13:05 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Sep 2008 01:58:50 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Losic",
"B.",
""
],
[
"Unruh",
"W. G.",
""
]
] | We present a gauge invariant argument that a nonlocal measure of second-order metric and matter perturbations dominate that of linear fluctuations in its effect on the gravitational field in 'slow-rolling' spacetimes. |
1206.0915 | Prayush Kumar | Prayush Kumar | Search for the PN coefficients for the Energy flux through Gravitational
Waves from Black-Hole Binaries using Markov Chain Monte Carlo | (59 pgs, 25figs). Undergraduate Thesis submitted to Birla Institute
of Technology & Science, Pilani, India; on 15th December, 2008 | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, the focus is on the improvement of the existing post-Newtonian
approximation for the gravitational flux from Super Massive Black Hole
Binaries. In order to improve the existing templates for LISA, we need more
accurate post-Newtonian expansions for the gravitational flux. Stochastic
search techniques like the Markov Chain Monte Carlo (MCMC) have been used
extensively for searching for sky parameters etc. The idea is to combine the
two and approach the problem of finding post-Newtonian coefficients using MCMC.
It has been shown that matching against a 5.5PN signal, with noise, the last
coefficient can be found by MCMC very easily and displays fast convergence.
Also the space for higher dimensional searches are explored.
| [
{
"created": "Tue, 5 Jun 2012 13:06:36 GMT",
"version": "v1"
}
] | 2012-06-06 | [
[
"Kumar",
"Prayush",
""
]
] | In this work, the focus is on the improvement of the existing post-Newtonian approximation for the gravitational flux from Super Massive Black Hole Binaries. In order to improve the existing templates for LISA, we need more accurate post-Newtonian expansions for the gravitational flux. Stochastic search techniques like the Markov Chain Monte Carlo (MCMC) have been used extensively for searching for sky parameters etc. The idea is to combine the two and approach the problem of finding post-Newtonian coefficients using MCMC. It has been shown that matching against a 5.5PN signal, with noise, the last coefficient can be found by MCMC very easily and displays fast convergence. Also the space for higher dimensional searches are explored. |
gr-qc/0111049 | Kirill Krasnov | Kirill Krasnov | Analytic Continuation for Asymptotically AdS 3D Gravity | 28 pages, 14 figures | Class.Quant.Grav. 19 (2002) 2399-2424 | 10.1088/0264-9381/19/9/306 | null | gr-qc hep-th math.CV | null | We have previously proposed that asymptotically AdS 3D wormholes and black
holes can be analytically continued to the Euclidean signature. The analytic
continuation procedure was described for non-rotating spacetimes, for which a
plane t=0 of time symmetry exists. The resulting Euclidean manifolds turned out
to be handlebodies whose boundary is the Schottky double of the geometry of the
t=0 plane. In the present paper we generalize this analytic continuation map to
the case of rotating wormholes. The Euclidean manifolds we obtain are quotients
of the hyperbolic space by a certain quasi-Fuchsian group. The group is the
Fenchel-Nielsen deformation of the group of the non-rotating spacetime. The
angular velocity of an asymptotic region is shown to be related to the
Fenchel-Nielsen twist. This solves the problem of classification of rotating
black holes and wormholes in 2+1 dimensions: the spacetimes are parametrized by
the moduli of the boundary of the corresponding Euclidean spaces. We also
comment on the thermodynamics of the wormhole spacetimes.
| [
{
"created": "Fri, 16 Nov 2001 02:54:32 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Krasnov",
"Kirill",
""
]
] | We have previously proposed that asymptotically AdS 3D wormholes and black holes can be analytically continued to the Euclidean signature. The analytic continuation procedure was described for non-rotating spacetimes, for which a plane t=0 of time symmetry exists. The resulting Euclidean manifolds turned out to be handlebodies whose boundary is the Schottky double of the geometry of the t=0 plane. In the present paper we generalize this analytic continuation map to the case of rotating wormholes. The Euclidean manifolds we obtain are quotients of the hyperbolic space by a certain quasi-Fuchsian group. The group is the Fenchel-Nielsen deformation of the group of the non-rotating spacetime. The angular velocity of an asymptotic region is shown to be related to the Fenchel-Nielsen twist. This solves the problem of classification of rotating black holes and wormholes in 2+1 dimensions: the spacetimes are parametrized by the moduli of the boundary of the corresponding Euclidean spaces. We also comment on the thermodynamics of the wormhole spacetimes. |
2209.00577 | Daan Janssen | Daan W. Janssen and Rainer Verch | Hadamard states on spherically symmetric characteristic surfaces, the
semi-classical Einstein equations and the Hawking effect | 34 pages, 6 pages appendix, 3 figures. v2: typographical corrections,
reordered bibliography, numbered equations, additional references added, more
detail added on certain definitions and derivations in appendix, expanded
discussion on Minkowski vacuum state | null | 10.1088/1361-6382/acb039 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate quasi-free Hadamard states defined via characteristic initial
data on null cones centred at the axis of symmetry in spherically symmetric
space-times. We characterize the necessary singular behaviour of null boundary
two-point functions such that one can define non-linear observables at this
null boundary and give formulas for the calculation of these observables. These
results extend earlier characterizations of null boundary states defining
Hadamard states in the bulk of the null cone. As an application of our derived
formulas, we consider their implications for the semi-classical Einstein
equations and calculate the vacuum polarization associated with Hawking
radiation near a collapsing body.
| [
{
"created": "Thu, 1 Sep 2022 16:46:58 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Jan 2023 12:50:57 GMT",
"version": "v2"
}
] | 2023-01-06 | [
[
"Janssen",
"Daan W.",
""
],
[
"Verch",
"Rainer",
""
]
] | We investigate quasi-free Hadamard states defined via characteristic initial data on null cones centred at the axis of symmetry in spherically symmetric space-times. We characterize the necessary singular behaviour of null boundary two-point functions such that one can define non-linear observables at this null boundary and give formulas for the calculation of these observables. These results extend earlier characterizations of null boundary states defining Hadamard states in the bulk of the null cone. As an application of our derived formulas, we consider their implications for the semi-classical Einstein equations and calculate the vacuum polarization associated with Hawking radiation near a collapsing body. |
0907.4057 | Mairi Sakellariadou | William Nelson and Mairi Sakellariadou | Unstable Anisotropic Loop Quantum Cosmology | 13 pages, 2 figures | Phys.Rev.D80:063521,2009 | 10.1103/PhysRevD.80.063521 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study stability conditions of the full Hamiltonian constraint equation
describing the quantum dynamics of the diagonal Bianchi I model in the context
of LQC. Our analysis has shown robust evidence of an instability in the
explicit implementation of the difference equation, implying important
consequences for the correspondence between the full LQG theory and LQC. As a
result, one may question the choice of the quantisation approach, the model of
lattice refinement, and/or the role of the ambiguity parameters; all these
should in principle be dictated by the full LQG theory.
| [
{
"created": "Thu, 23 Jul 2009 13:22:04 GMT",
"version": "v1"
}
] | 2009-11-06 | [
[
"Nelson",
"William",
""
],
[
"Sakellariadou",
"Mairi",
""
]
] | We study stability conditions of the full Hamiltonian constraint equation describing the quantum dynamics of the diagonal Bianchi I model in the context of LQC. Our analysis has shown robust evidence of an instability in the explicit implementation of the difference equation, implying important consequences for the correspondence between the full LQG theory and LQC. As a result, one may question the choice of the quantisation approach, the model of lattice refinement, and/or the role of the ambiguity parameters; all these should in principle be dictated by the full LQG theory. |
gr-qc/0502064 | Alessandro Nagar | Alessandro Nagar and Luciano Rezzolla | Gauge-invariant Non-spherical Metric Perturbations of Schwarzschild
Black-Hole Spacetimes | 24 pages, no figures, published as Classical and Quantum Gravity
topical review. Misprints present in the published version are corrected. A
few more typos in Eqs.(87) and (91) are corrected in the latest arXiv
submission | Class.Quant.Grav.22:R167,2005; Erratum-ibid.23:4297,2006 | 10.1088/0264-9381/22/16/R01 10.1088/0264-9381/23/12/C01 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The theory of gauge-invariant non-spherical metric perturbations of
Schwarzschild black hole spacetimes is now well established. Yet, as different
notations and conventions have been used throughout the years, the literature
on the subject is often confusing and sometimes confused. The purpose of this
paper is to review and collect the relevant expressions related to the
Regge-Wheeler and Zerilli equations for the odd and even-parity perturbations
of a Schwarzschild spacetime. Special attention is paid to the form they assume
in the presence of matter-sources and, for the two most popular conventions in
the literature, to the asymptotic expressions and gravitational-wave
amplitudes. Besides pointing out some inconsistencies in the literature, the
expressions collected here could serve as a quick reference for the calculation
of the perturbations of Schwarzschild black hole spacetimes driven by generic
sources and for those approaches in which gravitational waves are extracted
from numerically generated spacetimes.
| [
{
"created": "Mon, 14 Feb 2005 17:18:30 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Jun 2005 11:09:57 GMT",
"version": "v2"
},
{
"created": "Sat, 16 Jul 2005 12:07:26 GMT",
"version": "v3"
},
{
"created": "Sun, 2 Apr 2006 13:32:11 GMT",
"version": "v4"
},
{
"cr... | 2020-09-08 | [
[
"Nagar",
"Alessandro",
""
],
[
"Rezzolla",
"Luciano",
""
]
] | The theory of gauge-invariant non-spherical metric perturbations of Schwarzschild black hole spacetimes is now well established. Yet, as different notations and conventions have been used throughout the years, the literature on the subject is often confusing and sometimes confused. The purpose of this paper is to review and collect the relevant expressions related to the Regge-Wheeler and Zerilli equations for the odd and even-parity perturbations of a Schwarzschild spacetime. Special attention is paid to the form they assume in the presence of matter-sources and, for the two most popular conventions in the literature, to the asymptotic expressions and gravitational-wave amplitudes. Besides pointing out some inconsistencies in the literature, the expressions collected here could serve as a quick reference for the calculation of the perturbations of Schwarzschild black hole spacetimes driven by generic sources and for those approaches in which gravitational waves are extracted from numerically generated spacetimes. |
1205.5336 | Ozgur Delice | \"Ozg\"ur Delice, P{\i}nar Kirezli, Dilek K. \c{C}iftci | Higher Dimensional Cylindrical or Kasner Type Electrovacuum Solutions | 16 pages, Revtex. Text and references are extended, Published version | Gen. Relativ. Gravit. 45, 2251 (2013) | 10.1007/s10714-013-1583-0 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a D dimensional Kasner type diagonal spacetime where metric
functions depend only on a single coordinate and electromagnetic field shares
the symmetries of spacetime. These solutions can describe static cylindrical or
cosmological Einstein-Maxwell vacuum spacetimes. We mainly focus on
electrovacuum solutions and four different types of solutions are obtained in
which one of them has no four dimensional counterpart. We also consider the
properties of the general solution corresponding to the exterior field of a
charged line mass and discuss its several properties. Although it resembles the
same form with four dimensional one, there is a difference on the range of the
solutions for fixed signs of the parameters. General magnetic field vacuum
solution are also briefly discussed, which reduces to Bonnor-Melvin magnetic
universe for a special choice of the parameters. The Kasner forms of the
general solution are also presented for the cylindrical or cosmological cases.
| [
{
"created": "Thu, 24 May 2012 05:51:14 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Sep 2013 14:59:36 GMT",
"version": "v2"
}
] | 2013-10-31 | [
[
"Delice",
"Özgür",
""
],
[
"Kirezli",
"Pınar",
""
],
[
"Çiftci",
"Dilek K.",
""
]
] | We consider a D dimensional Kasner type diagonal spacetime where metric functions depend only on a single coordinate and electromagnetic field shares the symmetries of spacetime. These solutions can describe static cylindrical or cosmological Einstein-Maxwell vacuum spacetimes. We mainly focus on electrovacuum solutions and four different types of solutions are obtained in which one of them has no four dimensional counterpart. We also consider the properties of the general solution corresponding to the exterior field of a charged line mass and discuss its several properties. Although it resembles the same form with four dimensional one, there is a difference on the range of the solutions for fixed signs of the parameters. General magnetic field vacuum solution are also briefly discussed, which reduces to Bonnor-Melvin magnetic universe for a special choice of the parameters. The Kasner forms of the general solution are also presented for the cylindrical or cosmological cases. |
2010.01353 | Sergey Bondarenko | S.Bondarenko | CPTM symmetry, closed time paths and cosmological constant problem in
the formalism of extended manifold | 30 pages, 1 fugure | null | 10.1140/epjc/s10052-021-09045-4 | null | gr-qc cond-mat.other hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The problem of the cosmological constant is considered in the formalism of an
extended space-time consisting of the extended classical solution of Einstein
equations. The different regions of the extended manifold are proposed to be
related by the charge, parity, time and mass (CPTM) reversal symmetry applied
with respect to the metric fields of the manifolds. There are interactions
between the points of the extended manifold provided by scalar fields present
separately in the different patches of the extended solution. The value of the
constant is obtained equal to zero at the classical level due the mutual
contribution of the fields in the vacuum energy, it's non-zero value is due the
quantum interactions between the fields. There are few possible scenario for
the actions of the fields are discussed. Each from the obtained variants is
similar to the closed time path approach of non-equilibrium condensed matter
physics and among these possibilities for the closed paths, there is a variant
of the action equivalent to the formalism of Keldysh. Accordingly, we consider
and shortly discuss the application of the proposed formalism to the problem of
smallness of the cosmological constant and singularities problem.
| [
{
"created": "Sat, 3 Oct 2020 13:26:07 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Oct 2020 07:41:46 GMT",
"version": "v2"
},
{
"created": "Wed, 2 Dec 2020 11:25:19 GMT",
"version": "v3"
},
{
"created": "Thu, 18 Feb 2021 09:32:51 GMT",
"version": "v4"
}
] | 2021-04-07 | [
[
"Bondarenko",
"S.",
""
]
] | The problem of the cosmological constant is considered in the formalism of an extended space-time consisting of the extended classical solution of Einstein equations. The different regions of the extended manifold are proposed to be related by the charge, parity, time and mass (CPTM) reversal symmetry applied with respect to the metric fields of the manifolds. There are interactions between the points of the extended manifold provided by scalar fields present separately in the different patches of the extended solution. The value of the constant is obtained equal to zero at the classical level due the mutual contribution of the fields in the vacuum energy, it's non-zero value is due the quantum interactions between the fields. There are few possible scenario for the actions of the fields are discussed. Each from the obtained variants is similar to the closed time path approach of non-equilibrium condensed matter physics and among these possibilities for the closed paths, there is a variant of the action equivalent to the formalism of Keldysh. Accordingly, we consider and shortly discuss the application of the proposed formalism to the problem of smallness of the cosmological constant and singularities problem. |
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