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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2003.11020 | Konstantin Osetrin | Evgeny Osetrin, Konstantin Osetrin, Altair Filippov | Spatially homogeneous models of St\"ackel spacetimes of type (2.1) | 10 pages. arXiv admin note: substantial text overlap with
arXiv:2003.10141 | null | 10.1007/s11182-020-02051-1 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | All classes of spatially homogeneous space-time models are found that allow
the integration of the equations of motion of test particles and the eikonal
equation by the method of complete separation of variables according to type
(2.1). Four classes of model data are obtained. The resulting models can be
applied in any modified metric theories of gravity. Two of the above models
allow solutions of the Einstein equations with a cosmological constant and
radiation. For the models of a spatially homogeneous Universe with a
cosmological constant and radiation obtained in Einstein's theory of gravity,
the Hamilton-Jacobi equations of motion of the test particles and the eikonal
equation for radiation are integrated by the method of separation of variables.
| [
{
"created": "Mon, 23 Mar 2020 10:14:29 GMT",
"version": "v1"
}
] | 2020-08-26 | [
[
"Osetrin",
"Evgeny",
""
],
[
"Osetrin",
"Konstantin",
""
],
[
"Filippov",
"Altair",
""
]
] | All classes of spatially homogeneous space-time models are found that allow the integration of the equations of motion of test particles and the eikonal equation by the method of complete separation of variables according to type (2.1). Four classes of model data are obtained. The resulting models can be applied in any modified metric theories of gravity. Two of the above models allow solutions of the Einstein equations with a cosmological constant and radiation. For the models of a spatially homogeneous Universe with a cosmological constant and radiation obtained in Einstein's theory of gravity, the Hamilton-Jacobi equations of motion of the test particles and the eikonal equation for radiation are integrated by the method of separation of variables. |
gr-qc/0411007 | Xinhe Meng | Xin He Meng and Peng Wang | Palatini formulation of the $R^{-1}$modified gravity with an
additionally squared scalar curvature term | 14 pages, accepted for publication by CQG | Class.Quant.Grav. 22 (2005) 23-32 | 10.1088/0264-9381/22/1/002 | null | gr-qc | null | In this paper by deriving the Modified Friedmann equation in the Palatini
formulation of $R^2$ gravity, first we discuss the problem of whether in
Palatini formulation an additional $R^2$ term in Einstein's General Relativity
action can drive an inflation. We show that the Palatini formulation of $R^2$
gravity cannot lead to the gravity-driven inflation as in the metric formalism.
If considering no zero radiation and matter energy densities, we obtain that
only under rather restrictive assumption about the radiation and matter energy
densities there will be a mild power-law inflation $a(t)\sim t^2$, which is
obviously different from the original vacuum energy-like driven inflation. Then
we demonstrate that in the Palatini formulation of a more generally modified
gravity, i.e., the $1/R+R^2$ model that intends to explain both the current
cosmic acceleration and early time inflation, accelerating cosmic expansion
achieved at late Universe evolution times under the model parameters satisfying
$\alpha\ll\beta$.
| [
{
"created": "Sat, 30 Oct 2004 22:39:38 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Meng",
"Xin He",
""
],
[
"Wang",
"Peng",
""
]
] | In this paper by deriving the Modified Friedmann equation in the Palatini formulation of $R^2$ gravity, first we discuss the problem of whether in Palatini formulation an additional $R^2$ term in Einstein's General Relativity action can drive an inflation. We show that the Palatini formulation of $R^2$ gravity cannot lead to the gravity-driven inflation as in the metric formalism. If considering no zero radiation and matter energy densities, we obtain that only under rather restrictive assumption about the radiation and matter energy densities there will be a mild power-law inflation $a(t)\sim t^2$, which is obviously different from the original vacuum energy-like driven inflation. Then we demonstrate that in the Palatini formulation of a more generally modified gravity, i.e., the $1/R+R^2$ model that intends to explain both the current cosmic acceleration and early time inflation, accelerating cosmic expansion achieved at late Universe evolution times under the model parameters satisfying $\alpha\ll\beta$. |
gr-qc/0110025 | Carlos F. Sopuerta | Carlos F. Sopuerta (RCG, Portsmouth U.) | Equilibrium configurations in the dynamics of irrotational dust matter | 25 pages, LaTeX2e, IOP style. To appear in Classical and Quantum
Gravity | Class.Quant.Grav. 18 (2001) 4779-4800 | 10.1088/0264-9381/18/22/305 | RCG 01/07 | gr-qc | null | Irrotational dust solutions of Einstein's equations are suitable models to
describe the general-relativistic aspects of the gravitational instability
mechanism for the formation of cosmic structures. In this paper we study their
state space by considering the local initial-value problem formulated in the
covariant fluid approach. We consider a wide range of models, from homogeneous
and isotropic to highly inhomogeneous irrotational dust models, showing how
they constitute equilibrium configurations (invariant sets) of the dynamics.
Moreover, we give the characterization of such configurations, which provides
an initial-data characterization of the models under consideration.
| [
{
"created": "Thu, 4 Oct 2001 12:55:35 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Sopuerta",
"Carlos F.",
"",
"RCG, Portsmouth U."
]
] | Irrotational dust solutions of Einstein's equations are suitable models to describe the general-relativistic aspects of the gravitational instability mechanism for the formation of cosmic structures. In this paper we study their state space by considering the local initial-value problem formulated in the covariant fluid approach. We consider a wide range of models, from homogeneous and isotropic to highly inhomogeneous irrotational dust models, showing how they constitute equilibrium configurations (invariant sets) of the dynamics. Moreover, we give the characterization of such configurations, which provides an initial-data characterization of the models under consideration. |
0909.1541 | Alex Bernardini | Alex E. Bernardini, O. Bertolami | Stability of mass varying particle lumps | 26 pages, 7 figures | Phys.Rev. D80 (2009) 123011 | 10.1103/PhysRevD.80.123011 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The theoretical description of compact structures that share some key
features with mass varying particles allows for a simple analysis of
equilibrium and stability for massive stellar bodies. We investigate static,
spherically symmetric solutions of Einstein equations for a system composed by
nonbaryonic matter (neutrinos or dark matter) which forms stable structures
through attractive forces mediated by a background scalar-field (dark energy).
Assuming that the dark matter, or massive neutrinos, consist of a gas of weakly
interacting particles, the coupling with the scalar field is translated into an
effective dependence of the mass of the compounding particle on the radial
coordinate of the curved spacetime. The stability analysis reveals that these
static solutions become dynamically unstable for different Buchdahl limits of
the ratio between the total mass-energy and the stellar radius, $M/R$. We also
find regular solutions that for an external observer resemble Schwarzschild
black-holes. Our analysis leaves unanswered the question whether such
solutions, which are both regular and stable, do exist.
| [
{
"created": "Tue, 8 Sep 2009 18:47:38 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Dec 2009 12:34:22 GMT",
"version": "v2"
}
] | 2010-01-05 | [
[
"Bernardini",
"Alex E.",
""
],
[
"Bertolami",
"O.",
""
]
] | The theoretical description of compact structures that share some key features with mass varying particles allows for a simple analysis of equilibrium and stability for massive stellar bodies. We investigate static, spherically symmetric solutions of Einstein equations for a system composed by nonbaryonic matter (neutrinos or dark matter) which forms stable structures through attractive forces mediated by a background scalar-field (dark energy). Assuming that the dark matter, or massive neutrinos, consist of a gas of weakly interacting particles, the coupling with the scalar field is translated into an effective dependence of the mass of the compounding particle on the radial coordinate of the curved spacetime. The stability analysis reveals that these static solutions become dynamically unstable for different Buchdahl limits of the ratio between the total mass-energy and the stellar radius, $M/R$. We also find regular solutions that for an external observer resemble Schwarzschild black-holes. Our analysis leaves unanswered the question whether such solutions, which are both regular and stable, do exist. |
gr-qc/9705059 | Carlo Rovelli | Carlo Rovelli and Thomas Thiemann | The Immirzi parameter in quantum general relativity | 6 pages, no figures, LaTeX, revtex | Phys.Rev. D57 (1998) 1009-1014 | 10.1103/PhysRevD.57.1009 | Preprint HUTMP-97/B-366 | gr-qc | null | Barbero has generalized the Ashtekar canonical transformation to a
one-parameter scale transformation $U(\iota)$ on the phase space of general
relativity. Immirzi has noticed that in loop quantum gravity this
transformation alters the spectra of geometrical quantities. We show that
$U(\iota)$ is a canonical transformation that cannot be implement unitarily in
the quantum theory. This implies that there exists a one-parameter quantization
ambiguity in quantum gravity, namely a free parameter that enters the
construction of the quantum theory. The purpose of this letter is to elucidate
the origin and the role of this free parameter.
| [
{
"created": "Thu, 22 May 1997 08:24:15 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Rovelli",
"Carlo",
""
],
[
"Thiemann",
"Thomas",
""
]
] | Barbero has generalized the Ashtekar canonical transformation to a one-parameter scale transformation $U(\iota)$ on the phase space of general relativity. Immirzi has noticed that in loop quantum gravity this transformation alters the spectra of geometrical quantities. We show that $U(\iota)$ is a canonical transformation that cannot be implement unitarily in the quantum theory. This implies that there exists a one-parameter quantization ambiguity in quantum gravity, namely a free parameter that enters the construction of the quantum theory. The purpose of this letter is to elucidate the origin and the role of this free parameter. |
2002.01897 | Macarena Lagos | Macarena Lagos, Pedro G. Ferreira, Oliver J. Tattersall | Anomalous decay rate of quasinormal modes | Updated to published version | Phys. Rev. D 101, 084018 (2020) | 10.1103/PhysRevD.101.084018 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The decay timescales of the quasinormal modes of a massive scalar field have
an intriguing behavior: they either grow or decay with increasing angular
harmonic numbers $\ell$, depending on whether the mass of the scalar field is
small or large. We identify the properties of the effective potential of the
scalar field that leads to this behavior and characterize it in detail. If the
scalar field is non-minimally coupled, considered here, the scalar quasinormal
modes will leak into the gravitational wave signal and will have decaying times
that are comparable or smaller than those typical in General Relativity. Hence,
these modes could be detectable in the future. Finally, we find that the
anomalous behavior in the decay timescales of quasinormal modes is present in a
much larger class of models beyond a simple massive scalar field.
| [
{
"created": "Wed, 5 Feb 2020 17:59:45 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Apr 2020 14:34:35 GMT",
"version": "v2"
}
] | 2020-04-15 | [
[
"Lagos",
"Macarena",
""
],
[
"Ferreira",
"Pedro G.",
""
],
[
"Tattersall",
"Oliver J.",
""
]
] | The decay timescales of the quasinormal modes of a massive scalar field have an intriguing behavior: they either grow or decay with increasing angular harmonic numbers $\ell$, depending on whether the mass of the scalar field is small or large. We identify the properties of the effective potential of the scalar field that leads to this behavior and characterize it in detail. If the scalar field is non-minimally coupled, considered here, the scalar quasinormal modes will leak into the gravitational wave signal and will have decaying times that are comparable or smaller than those typical in General Relativity. Hence, these modes could be detectable in the future. Finally, we find that the anomalous behavior in the decay timescales of quasinormal modes is present in a much larger class of models beyond a simple massive scalar field. |
1708.04611 | Claus Gerhardt | Claus Gerhardt | The quantization of a Kerr-AdS black hole | 20 pages. arXiv admin note: substantial text overlap with
arXiv:1608.08209 | Advances in Mathematical Physics vol. 2018 (2018), Article ID
4328312, 10 pages | 10.1155/2018/4328312 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We apply our model of quantum gravity to a Kerr-AdS spacetime of dimension $2
m+1$, $m\ge2$, where all rotational parameters are equal, resulting in a wave
equation in a quantum spacetime which has a sequence of solutions that can be
expressed as a product of stationary and temporal eigenfunctions. The
stationary eigenfunctions can be interpreted as radiation and the temporal as
gravitational waves. The event horizon corresponds in the quantum model to a
Cauchy hypersurface that can be crossed by causal curves in both directions
such that the information paradox does not occur. We also prove that the
Kerr-AdS spacetime can be maximally extended by replacing in a generalized
Boyer-Lindquist coordinate system the $r$ variable by $\rho=r^2$ such that the
extended spacetime has a timelike curvature singularity in $\rho=-a^2$.
| [
{
"created": "Wed, 9 Aug 2017 10:47:13 GMT",
"version": "v1"
}
] | 2018-02-06 | [
[
"Gerhardt",
"Claus",
""
]
] | We apply our model of quantum gravity to a Kerr-AdS spacetime of dimension $2 m+1$, $m\ge2$, where all rotational parameters are equal, resulting in a wave equation in a quantum spacetime which has a sequence of solutions that can be expressed as a product of stationary and temporal eigenfunctions. The stationary eigenfunctions can be interpreted as radiation and the temporal as gravitational waves. The event horizon corresponds in the quantum model to a Cauchy hypersurface that can be crossed by causal curves in both directions such that the information paradox does not occur. We also prove that the Kerr-AdS spacetime can be maximally extended by replacing in a generalized Boyer-Lindquist coordinate system the $r$ variable by $\rho=r^2$ such that the extended spacetime has a timelike curvature singularity in $\rho=-a^2$. |
gr-qc/9911069 | Juan Eloy Ayon Beato | Eloy Ay\'on-Beato, Alberto Garc\'ia, Alfredo Mac\'ias and Hernando
Quevedo | Uniqueness theorems for static black holes in metric-affine gravity | 12 pages, RevTex, to appear in Phys. Rev. D | Phys.Rev. D61 (2000) 084017 | 10.1103/PhysRevD.61.084017 | null | gr-qc hep-th | null | Using the equivalence theorem for the triplet ansatz sector of metric-affine
gravity (MAG) theories and the Einstein-Proca system, it is shown that the only
static black hole of the triplet sector of MAG is the Schwarzschild solution,
under the constraint (-4\beta_4 + k_1\beta_5/2k_0 + k_2\gamma_4/k_0)/\kappa z_4
\neq 0 on the coupling constants. For the special case (-4\beta_4 +
k_1\beta_5/2k_0 + k_2\gamma_4/k_0)/\kappa z_4 = 0, it follows that the only
static non-extremal black hole is the Reissner-Nordstr\"om one. The results can
be extended to exclude also the existence of soliton solutions of the triplet
sector of MAG.
| [
{
"created": "Fri, 19 Nov 1999 00:00:46 GMT",
"version": "v1"
}
] | 2016-08-15 | [
[
"Ayón-Beato",
"Eloy",
""
],
[
"García",
"Alberto",
""
],
[
"Macías",
"Alfredo",
""
],
[
"Quevedo",
"Hernando",
""
]
] | Using the equivalence theorem for the triplet ansatz sector of metric-affine gravity (MAG) theories and the Einstein-Proca system, it is shown that the only static black hole of the triplet sector of MAG is the Schwarzschild solution, under the constraint (-4\beta_4 + k_1\beta_5/2k_0 + k_2\gamma_4/k_0)/\kappa z_4 \neq 0 on the coupling constants. For the special case (-4\beta_4 + k_1\beta_5/2k_0 + k_2\gamma_4/k_0)/\kappa z_4 = 0, it follows that the only static non-extremal black hole is the Reissner-Nordstr\"om one. The results can be extended to exclude also the existence of soliton solutions of the triplet sector of MAG. |
1404.6536 | Monica Forte | M\'onica Forte | Linking phantom quintessences and tachyons | 3 pages, no figures, accepted for publication in Phys. Rev. D | null | 10.1103/PhysRevD.90.027302 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a nonparametric form-invariance transformation through which we
establish a link between phantom and tachyonic models in flat
Friedmann-Robertson-Walker cosmologies.
| [
{
"created": "Thu, 24 Apr 2014 19:42:45 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Jun 2014 22:28:22 GMT",
"version": "v2"
}
] | 2015-06-19 | [
[
"Forte",
"Mónica",
""
]
] | We present a nonparametric form-invariance transformation through which we establish a link between phantom and tachyonic models in flat Friedmann-Robertson-Walker cosmologies. |
0905.4562 | Valter Moretti | Lorenzo Franceschini | Topological sectors for Weyl-algebra net in the Einstein cylindrical
universe | Ph.D. Thesis - University of Trento, Department of Mathematics, 126
pages | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper is an extended and more detailed version of arXiv:0812.0533. We
tackle the problem of constructing explicit examples of topological cocycles of
Roberts' net cohomology, as defined abstractly by Brunetti and Ruzzi. We
consider the simple case of massive bosonic quantum field theory on the two
dimensional Einstein cylinder. After deriving some crucial results of the
algebraic framework of quantization, we address the problem of the construction
of the topological cocycles. All constructed cocycles lead to unitarily
equivalent representations of the fundamental group of the circle (seen as a
diffeomorphic image of all possible Cauchy surfaces).
| [
{
"created": "Thu, 28 May 2009 06:48:39 GMT",
"version": "v1"
}
] | 2009-05-30 | [
[
"Franceschini",
"Lorenzo",
""
]
] | This paper is an extended and more detailed version of arXiv:0812.0533. We tackle the problem of constructing explicit examples of topological cocycles of Roberts' net cohomology, as defined abstractly by Brunetti and Ruzzi. We consider the simple case of massive bosonic quantum field theory on the two dimensional Einstein cylinder. After deriving some crucial results of the algebraic framework of quantization, we address the problem of the construction of the topological cocycles. All constructed cocycles lead to unitarily equivalent representations of the fundamental group of the circle (seen as a diffeomorphic image of all possible Cauchy surfaces). |
gr-qc/9805085 | Andrew P. Billyard | A. P. Billyard, A. A. Coley, R. J. van den Hoogen | The stability of cosmological scaling solutions | AMSTeX, 7 pages, re-submitted to Phys Rev Lett | Phys.Rev. D58 (1998) 123501 | 10.1103/PhysRevD.58.123501 | Dal-98-08 | gr-qc hep-th | null | We study the stability of cosmological scaling solutions within the class of
spatially homogeneous cosmological models with a perfect fluid subject to the
equation of state p_gamma=(gamma-1) rho_gamma (where gamma is a constant
satisfying 0 < gamma < 2) and a scalar field with an exponential potential. The
scaling solutions, which are spatially flat isotropic models in which the
scalar field energy density tracks that of the perfect fluid, are of physical
interest. For example, in these models a significant fraction of the current
energy density of the Universe may be contained in the scalar field whose
dynamical effects mimic cold dark matter. It is known that the scaling
solutions are late-time attractors (i.e., stable) in the subclass of flat
isotropic models. We find that the scaling solutions are stable (to shear and
curvature perturbations) in generic anisotropic Bianchi models when gamma <
2/3. However, when gamma > 2/3, and particularly for realistic matter with
gamma >= 1, the scaling solutions are unstable; essentially they are unstable
to curvature perturbations, although they are stable to shear perturbations. We
briefly discuss the physical consequences of these results.
| [
{
"created": "Thu, 21 May 1998 15:30:53 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Jul 1998 17:41:53 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Billyard",
"A. P.",
""
],
[
"Coley",
"A. A.",
""
],
[
"Hoogen",
"R. J. van den",
""
]
] | We study the stability of cosmological scaling solutions within the class of spatially homogeneous cosmological models with a perfect fluid subject to the equation of state p_gamma=(gamma-1) rho_gamma (where gamma is a constant satisfying 0 < gamma < 2) and a scalar field with an exponential potential. The scaling solutions, which are spatially flat isotropic models in which the scalar field energy density tracks that of the perfect fluid, are of physical interest. For example, in these models a significant fraction of the current energy density of the Universe may be contained in the scalar field whose dynamical effects mimic cold dark matter. It is known that the scaling solutions are late-time attractors (i.e., stable) in the subclass of flat isotropic models. We find that the scaling solutions are stable (to shear and curvature perturbations) in generic anisotropic Bianchi models when gamma < 2/3. However, when gamma > 2/3, and particularly for realistic matter with gamma >= 1, the scaling solutions are unstable; essentially they are unstable to curvature perturbations, although they are stable to shear perturbations. We briefly discuss the physical consequences of these results. |
gr-qc/0004065 | Luis Lehner | Luis Lehner, Mijan Huq and David Garrison | Notes on causal differencing in ADM/CADM formulations: a 1D comparison | 11 pages, 6 figures. These notes illustrate how excision techniques
already developed for ADM (in the form usually used in numerical relativity)
codes can be straightforwardly applied in the so called `conformal ADM'. A
comparison of the solutions obtained with both formulations is carried out
highlighting when either formulation can yield better behaved evolutions | null | null | null | gr-qc | null | Causal differencing has shown to be one of the promising and successful
approaches towards excising curvature singularities from numerical simulations
of black hole spacetimes. So far it has only been actively implemented in the
ADM and Einstein-Bianchi 3+1 formulations of the Einstein equations. Recently,
an approach closely related to the ADM one, commonly referred to as as
``conformal ADM'' (CADM) has shown excellent results when modeling waves on
flat spacetimes and black hole spacetimes where singularity avoiding slices are
used to deal with the singularity. In these cases, the use of CADM has yielded
longer evolutions and better outer boundary dependence than those obtained with
the ADM one. If this success translates to the case where excision is
implemented, then the CADM formulation will likely be a prime candidate for
modeling generic black hole spacetimes. In the present work we investigate the
applicability of causal differencing to CADM, presenting the equations in a
convenient way for such a goal and compare its application with the ADM
approach in 1D.
| [
{
"created": "Wed, 19 Apr 2000 22:45:24 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Lehner",
"Luis",
""
],
[
"Huq",
"Mijan",
""
],
[
"Garrison",
"David",
""
]
] | Causal differencing has shown to be one of the promising and successful approaches towards excising curvature singularities from numerical simulations of black hole spacetimes. So far it has only been actively implemented in the ADM and Einstein-Bianchi 3+1 formulations of the Einstein equations. Recently, an approach closely related to the ADM one, commonly referred to as as ``conformal ADM'' (CADM) has shown excellent results when modeling waves on flat spacetimes and black hole spacetimes where singularity avoiding slices are used to deal with the singularity. In these cases, the use of CADM has yielded longer evolutions and better outer boundary dependence than those obtained with the ADM one. If this success translates to the case where excision is implemented, then the CADM formulation will likely be a prime candidate for modeling generic black hole spacetimes. In the present work we investigate the applicability of causal differencing to CADM, presenting the equations in a convenient way for such a goal and compare its application with the ADM approach in 1D. |
1909.06405 | Vyacheslav Dokuchaev | Victor Berezin, Vyacheslav Dokuchaev, Yury Eroshenko and Alexei
Smirnov | Least action principle and gravitational double layer | 8 pages | IJMPA 35, 2040002 (2020) | 10.1142/S0217751X20400023 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The higher derivative gravitational theories exhibit new phenomena absent in
General Relativity. One of them is the possible formation of the so called
double layer which is the pure gravitational phenomenon and can be interpreted,
in a sense, as the gravitational shock wave. In this paper we show how some
very important features of the double layer equations of motion can be
extracted straight from the least action principle.
| [
{
"created": "Fri, 13 Sep 2019 18:51:05 GMT",
"version": "v1"
}
] | 2020-03-20 | [
[
"Berezin",
"Victor",
""
],
[
"Dokuchaev",
"Vyacheslav",
""
],
[
"Eroshenko",
"Yury",
""
],
[
"Smirnov",
"Alexei",
""
]
] | The higher derivative gravitational theories exhibit new phenomena absent in General Relativity. One of them is the possible formation of the so called double layer which is the pure gravitational phenomenon and can be interpreted, in a sense, as the gravitational shock wave. In this paper we show how some very important features of the double layer equations of motion can be extracted straight from the least action principle. |
gr-qc/0604073 | Ramin G. Daghigh | Ramin G. Daghigh, Gabor Kunstatter, Dave Ostapchuk, and Vince Bagnulo | The Highly Damped Quasinormal Modes of $d$-dimensional
Reissner-Nordstrom Black Holes in the Small Charge Limit | 18 pages, 8 figures | Class.Quant.Grav. 23 (2006) 5101-5116 | 10.1088/0264-9381/23/17/002 | null | gr-qc | null | We analyze in detail the highly damped quasinormal modes of $d$-dimensional
Reissner-Nordstr$\ddot{\rm{o}}$m black holes with small charge, paying
particular attention to the large but finite damping limit in which the
Schwarzschild results should be valid. In the infinite damping limit, we
confirm using different methods the results obtained previously in the
literature for higher dimensional Reissner-Nordstr$\ddot{\rm{o}}$m black holes.
Using a combination of analytic and numerical techniques we also calculate the
transition of the real part of the quasinormal mode frequency from the
Reissner-Nordstr$\ddot{\rm{o}}$m value for very large damping to the
Schwarzschild value of $\ln(3) T_{bh}$ for intermediate damping. The real
frequency does not interpolate smoothly between the two values. Instead there
is a critical value of the damping at which the topology of the
Stokes/anti-Stokes lines change, and the real part of the quasinormal mode
frequency dips to zero.
| [
{
"created": "Mon, 17 Apr 2006 19:57:20 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Jun 2006 01:14:38 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Daghigh",
"Ramin G.",
""
],
[
"Kunstatter",
"Gabor",
""
],
[
"Ostapchuk",
"Dave",
""
],
[
"Bagnulo",
"Vince",
""
]
] | We analyze in detail the highly damped quasinormal modes of $d$-dimensional Reissner-Nordstr$\ddot{\rm{o}}$m black holes with small charge, paying particular attention to the large but finite damping limit in which the Schwarzschild results should be valid. In the infinite damping limit, we confirm using different methods the results obtained previously in the literature for higher dimensional Reissner-Nordstr$\ddot{\rm{o}}$m black holes. Using a combination of analytic and numerical techniques we also calculate the transition of the real part of the quasinormal mode frequency from the Reissner-Nordstr$\ddot{\rm{o}}$m value for very large damping to the Schwarzschild value of $\ln(3) T_{bh}$ for intermediate damping. The real frequency does not interpolate smoothly between the two values. Instead there is a critical value of the damping at which the topology of the Stokes/anti-Stokes lines change, and the real part of the quasinormal mode frequency dips to zero. |
gr-qc/0404061 | Claus Gerhardt | Claus Gerhardt | Transition from big crunch to big bang in brane cosmology | 20 pages, a pdf version can also be retrieved from
http://www.math.uni-heidelberg.de/studinfo/gerhardt/brane.pdf and bibtex data
from http://www.math.uni-heidelberg.de/studinfo/gerhardt/bibtexcgbrane.html,
v5: the results of http://arXiv.org/abs/gr-qc/0404112 have been applied to
ARW branes, the introduction has been rewritten, this is the final version
that will appear in Adv. Theor. Math. Physics | Adv.Theor.Math.Phys. 8 (2004) 319-343 | null | null | gr-qc hep-th math.DG | null | We consider branes $N=I\times\so$, where $\so$ is an $n$\ndash dimensional
space form, not necessarily compact, in a Schwarzschild-AdS_{(n+2)} bulk $\mc
N$. The branes have a big crunch singularity. If a brane is an ARW space, then,
under certain conditions, there exists a smooth natural transition flow through
the singularity to a reflected brane $\hat N$, which has a big bang singularity
and which can be viewed as a brane in a reflected Schwarzschild-AdS_{(n+2)}
bulk $\hat{\mc N}$. The joint branes $N\uu \hat N$ can thus be naturally
embedded in $R^2\times \so$, hence there exists a second possibility of
defining a smooth transition from big crunch to big bang by requiring that
$N\uu\hat N$ forms a $C^\infty$-hypersurface in $R^2\times \so$. This last
notion of a smooth transition also applies to branes that are not ARW spaces,
allowing a wide range of possible equations of state.
| [
{
"created": "Tue, 13 Apr 2004 19:52:25 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Apr 2004 13:10:38 GMT",
"version": "v2"
},
{
"created": "Mon, 19 Apr 2004 20:52:32 GMT",
"version": "v3"
},
{
"created": "Wed, 21 Apr 2004 14:28:21 GMT",
"version": "v4"
},
{
"created": "Sun, 23 May 2004 22:49:28 GMT",
"version": "v5"
}
] | 2007-05-23 | [
[
"Gerhardt",
"Claus",
""
]
] | We consider branes $N=I\times\so$, where $\so$ is an $n$\ndash dimensional space form, not necessarily compact, in a Schwarzschild-AdS_{(n+2)} bulk $\mc N$. The branes have a big crunch singularity. If a brane is an ARW space, then, under certain conditions, there exists a smooth natural transition flow through the singularity to a reflected brane $\hat N$, which has a big bang singularity and which can be viewed as a brane in a reflected Schwarzschild-AdS_{(n+2)} bulk $\hat{\mc N}$. The joint branes $N\uu \hat N$ can thus be naturally embedded in $R^2\times \so$, hence there exists a second possibility of defining a smooth transition from big crunch to big bang by requiring that $N\uu\hat N$ forms a $C^\infty$-hypersurface in $R^2\times \so$. This last notion of a smooth transition also applies to branes that are not ARW spaces, allowing a wide range of possible equations of state. |
1407.5989 | Deirdre Shoemaker | James Healy and Pablo Laguna and Deirdre Shoemaker | Decoding the final state in binary black hole mergers | null | null | 10.1088/0264-9381/31/21/212001 | null | gr-qc astro-ph.CO astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We demonstrate that in binary black hole mergers there is a direct
correlation between the frequency of the gravitational wave at peak amplitude
and the mass and spin of the final black hole. This correlation could
potentially assist with the analysis of gravitational wave observations from
binary black hole mergers.
| [
{
"created": "Tue, 22 Jul 2014 21:08:32 GMT",
"version": "v1"
}
] | 2015-06-22 | [
[
"Healy",
"James",
""
],
[
"Laguna",
"Pablo",
""
],
[
"Shoemaker",
"Deirdre",
""
]
] | We demonstrate that in binary black hole mergers there is a direct correlation between the frequency of the gravitational wave at peak amplitude and the mass and spin of the final black hole. This correlation could potentially assist with the analysis of gravitational wave observations from binary black hole mergers. |
0705.1836 | Saibal Ray | Saibal Ray, Utpal Mukhopadhyay and Partha Pratim Ghosh | Large Number Hypothesis: A Review | 21 pages Latex, 0 figures, submitted to GRG | null | null | null | gr-qc astro-ph | null | Large dimensionless numbers, arising out of ratios of various physical
constants, intrigued many scientists, especially Dirac. Relying on the
coincidence of large numbers, Dirac arrived at the revolutionary hypothesis
that the gravitational constant $G$ should vary inversely as the cosmic time
$t$. This hypothesis of Dirac, known as Large Number Hypothesis (LNH), sparked
off many speculations, arguments and new ideas in terms of applications. Works
done by several authors with LNH as their basic platform are reviewed in this
work. Relationship between some of those works are pointed out here.
Possibility of time-variations of physical constants other than $G$ are also
discussed.
| [
{
"created": "Sun, 13 May 2007 15:40:03 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Ray",
"Saibal",
""
],
[
"Mukhopadhyay",
"Utpal",
""
],
[
"Ghosh",
"Partha Pratim",
""
]
] | Large dimensionless numbers, arising out of ratios of various physical constants, intrigued many scientists, especially Dirac. Relying on the coincidence of large numbers, Dirac arrived at the revolutionary hypothesis that the gravitational constant $G$ should vary inversely as the cosmic time $t$. This hypothesis of Dirac, known as Large Number Hypothesis (LNH), sparked off many speculations, arguments and new ideas in terms of applications. Works done by several authors with LNH as their basic platform are reviewed in this work. Relationship between some of those works are pointed out here. Possibility of time-variations of physical constants other than $G$ are also discussed. |
0705.3587 | Shahram Jalalzadeh | P. Pedram, S. Jalalzadeh, and S. S. Gousheh | Schr\"odinger-Wheeler-DeWitt equation in chaplygin gas FRW cosmological
model | 11 pages, 1 figure, to appear in IJTP | Int.J.Theor.Phys.46:3201-3208,2007 | 10.1007/s10773-007-9436-9 | null | gr-qc | null | We present a chaplygin gas Friedmann-Robertson-Walker quantum cosmological
model. In this work the Schutz's variational formalism is applied with
positive, negative, and zero constant spatial curvature. In this approach the
notion of time can be recovered. These give rise to
Schr\"odinger-Wheeler-DeWitt equation for the scale factor. We use the
eigenfunctions in order to construct wave packets for each case. We study the
time dependent behavior of the expectation value of the scale factor, using the
many-worlds interpretations of quantum mechanics.
| [
{
"created": "Thu, 24 May 2007 14:01:26 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Pedram",
"P.",
""
],
[
"Jalalzadeh",
"S.",
""
],
[
"Gousheh",
"S. S.",
""
]
] | We present a chaplygin gas Friedmann-Robertson-Walker quantum cosmological model. In this work the Schutz's variational formalism is applied with positive, negative, and zero constant spatial curvature. In this approach the notion of time can be recovered. These give rise to Schr\"odinger-Wheeler-DeWitt equation for the scale factor. We use the eigenfunctions in order to construct wave packets for each case. We study the time dependent behavior of the expectation value of the scale factor, using the many-worlds interpretations of quantum mechanics. |
1704.07391 | Wolfgang Wieland | Wolfgang Wieland | New boundary variables for classical and quantum gravity on a null
surface | 41 pages, one figure | Class. Quantum Grav. 34 (2017), 215008 (30pp) | 10.1088/1361-6382/aa8d06 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The covariant Hamiltonian formulation for general relativity is studied in
terms of self-dual variables on a manifold with an internal and lightlike
boundary. At this inner boundary, new canonical variables appear: a spinor and
a spinor-valued two-form that encode the entire intrinsic geometry of the null
surface. At a two-dimensional cross-section of the boundary, quasi-local
expressions for the generators of two-dimensional diffeomorphisms, time
translations, and dilatations of the null normal are introduced and written in
terms of the new boundary variables. In addition, a generalisation of the
first-law of black-hole thermodynamics for arbitrary null surfaces is found,
and the relevance of the framework for non-perturbative quantum gravity is
stressed and explained.
| [
{
"created": "Mon, 24 Apr 2017 18:00:18 GMT",
"version": "v1"
}
] | 2017-11-07 | [
[
"Wieland",
"Wolfgang",
""
]
] | The covariant Hamiltonian formulation for general relativity is studied in terms of self-dual variables on a manifold with an internal and lightlike boundary. At this inner boundary, new canonical variables appear: a spinor and a spinor-valued two-form that encode the entire intrinsic geometry of the null surface. At a two-dimensional cross-section of the boundary, quasi-local expressions for the generators of two-dimensional diffeomorphisms, time translations, and dilatations of the null normal are introduced and written in terms of the new boundary variables. In addition, a generalisation of the first-law of black-hole thermodynamics for arbitrary null surfaces is found, and the relevance of the framework for non-perturbative quantum gravity is stressed and explained. |
gr-qc/0605144 | Lorenzo Iorio | Lorenzo Iorio | Perspectives in measuring the PPN parameters beta and gamma in the
Earth's gravitational fields with the CHAMP/GRACE models | LaTex2e, 14 pages, 3 tables, no figures, 75 references. To appear in
Int. J. Mod. Phys. D | Int.J.Mod.Phys.D17:815-829,2008 | 10.1142/S0218271808012516 | null | gr-qc astro-ph | null | The current bounds on the PPN parameters gamma and beta are of the order of
10^-4-10^-5. Various missions aimed at improving such limits by several orders
of magnitude have more or less recently been proposed like LATOR, ASTROD,
BepiColombo and GAIA. They involve the use of various spacecraft, to be
launched along interplanetary trajectories, for measuring the effects of the
solar gravity on the propagation of electromagnetic waves. In this paper we
investigate what is needed to measure the combination nu=(2+2gamma-beta)/3 of
the post-Newtonian gravitoelectric Einstein perigee precession of a test
particle to an accuracy of about 10^-5 with a pair of drag-free spacecraft in
the Earth's gravitational field. It turns out that the latest gravity models
from the dedicated CHAMP and GRACE missions would allow to reduce the
systematic error of gravitational origin just to this demanding level of
accuracy. In regard to the non-gravitational errors, the spectral noise density
of the drag-free sensors required to reach such level of accuracy would amounts
to 10^-8-10^-9 cm s^-2 Hz^-1/2 over very low frequencies. Although not yet
obtainable with the present technologies, such level of compensation is much
less demanding than those required for, e.g., LISA. As a by-product, an
independent measurement of the post-Newtonian gravitomagnetic Lense-Thirring
effect with a 0.9% accuracy would be possible as well. The forthcoming Earth
gravity models from CHAMP and GRACE will further reduce the systematic
gravitational errors in both of such tests.
| [
{
"created": "Tue, 30 May 2006 15:01:45 GMT",
"version": "v1"
},
{
"created": "Sun, 2 Jul 2006 14:51:47 GMT",
"version": "v2"
},
{
"created": "Sat, 16 Jun 2007 08:42:11 GMT",
"version": "v3"
},
{
"created": "Sun, 29 Jul 2007 15:40:53 GMT",
"version": "v4"
},
{
"created": "Sun, 11 Nov 2007 13:10:35 GMT",
"version": "v5"
}
] | 2008-11-26 | [
[
"Iorio",
"Lorenzo",
""
]
] | The current bounds on the PPN parameters gamma and beta are of the order of 10^-4-10^-5. Various missions aimed at improving such limits by several orders of magnitude have more or less recently been proposed like LATOR, ASTROD, BepiColombo and GAIA. They involve the use of various spacecraft, to be launched along interplanetary trajectories, for measuring the effects of the solar gravity on the propagation of electromagnetic waves. In this paper we investigate what is needed to measure the combination nu=(2+2gamma-beta)/3 of the post-Newtonian gravitoelectric Einstein perigee precession of a test particle to an accuracy of about 10^-5 with a pair of drag-free spacecraft in the Earth's gravitational field. It turns out that the latest gravity models from the dedicated CHAMP and GRACE missions would allow to reduce the systematic error of gravitational origin just to this demanding level of accuracy. In regard to the non-gravitational errors, the spectral noise density of the drag-free sensors required to reach such level of accuracy would amounts to 10^-8-10^-9 cm s^-2 Hz^-1/2 over very low frequencies. Although not yet obtainable with the present technologies, such level of compensation is much less demanding than those required for, e.g., LISA. As a by-product, an independent measurement of the post-Newtonian gravitomagnetic Lense-Thirring effect with a 0.9% accuracy would be possible as well. The forthcoming Earth gravity models from CHAMP and GRACE will further reduce the systematic gravitational errors in both of such tests. |
2404.07056 | Luisa Boglioni | Gabriele Barca, Luisa Boglioni, Giovanni Montani | Quantum Isotropic Universe in RQM Analogy: the Cosmological Horizon | null | Physics of the Dark Universe 45 (2024) 101540 | 10.1016/j.dark.2024.101540 | null | gr-qc hep-th quant-ph | http://creativecommons.org/licenses/by/4.0/ | We investigate the quantum dynamics of the isotropic Universe in the presence
of a free massless scalar field, playing the role of a physical clock. The
Hilbert space is constructed via a direct analogy between the Wheeler-DeWitt
equation in the minisuperspace and a relativistic scalar one in physical space.
In particular, we show how the introduction of a "turning point" in the
Universe evolution allows to overcome an intrinsic ambiguity in representing
the expanding and collapsing Universe. In this way, the positive and negative
frequencies are simply identified with time reversed states. The main subject
of the present analysis is the construction of a horizon operator, whose
quantum behavior is investigated when Polymer Quantum Mechanics is implemented
to describe the asymptotic evolution near the initial singularity. The reason
of this choice is motivated by the intrinsic spreading of localized wavepackets
when the polymer dispersion relation governs the quantum dynamics. The evidence
that the mean value of the quantum horizon operator follows its semiclassical
behavior (corrected for polymerization) is a clear indication that a concept of
causality can be restored also in the quantum cosmological picture.
| [
{
"created": "Wed, 10 Apr 2024 14:45:56 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Apr 2024 08:47:00 GMT",
"version": "v2"
},
{
"created": "Mon, 10 Jun 2024 15:52:20 GMT",
"version": "v3"
}
] | 2024-06-11 | [
[
"Barca",
"Gabriele",
""
],
[
"Boglioni",
"Luisa",
""
],
[
"Montani",
"Giovanni",
""
]
] | We investigate the quantum dynamics of the isotropic Universe in the presence of a free massless scalar field, playing the role of a physical clock. The Hilbert space is constructed via a direct analogy between the Wheeler-DeWitt equation in the minisuperspace and a relativistic scalar one in physical space. In particular, we show how the introduction of a "turning point" in the Universe evolution allows to overcome an intrinsic ambiguity in representing the expanding and collapsing Universe. In this way, the positive and negative frequencies are simply identified with time reversed states. The main subject of the present analysis is the construction of a horizon operator, whose quantum behavior is investigated when Polymer Quantum Mechanics is implemented to describe the asymptotic evolution near the initial singularity. The reason of this choice is motivated by the intrinsic spreading of localized wavepackets when the polymer dispersion relation governs the quantum dynamics. The evidence that the mean value of the quantum horizon operator follows its semiclassical behavior (corrected for polymerization) is a clear indication that a concept of causality can be restored also in the quantum cosmological picture. |
2208.12993 | Bayram Tekin | Emel Altas and Bayram Tekin | Hawking Temperature as the Total Gauss-Bonnet Invariant of the Region
Outside a Black Hole | 9 pages, 2 figure, extended version to appear in THE EUROPEAN
PHYSICAL JOURNAL C (Particles and Fields) | null | 10.1140/epjc/s10052-023-11594-9 | null | gr-qc hep-ph hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide two novel ways to compute the surface gravity ($\kappa$) and the
Hawking temperature $(T_{H})$ of a stationary black hole: in the first method
$T_{H}$ is given as the three-volume integral of the Gauss-Bonnet invariant (or
the Kretschmann scalar for Ricci-flat metrics) in the total region outside the
event horizon; in the second method it is given as the surface integral of the
Riemann tensor contracted with the covariant derivative of a Killing vector on
the event horizon. To arrive at these new formulas for the black hole
temperature (and the related surface gravity), we first construct a new
differential geometric identity using the Bianchi identity and an antisymmetric
rank-$2$ tensor, valid for spacetimes with at least one Killing vector field.
The Gauss-Bonnet tensor and the Gauss-Bonnet scalar play a particular role in
this geometric identity. We calculate the surface gravity and the Hawking
temperature of the Kerr and the extremal Reissner-Nordstr\"om holes as
examples.
| [
{
"created": "Sat, 27 Aug 2022 12:06:23 GMT",
"version": "v1"
},
{
"created": "Sat, 6 May 2023 14:12:24 GMT",
"version": "v2"
}
] | 2023-05-31 | [
[
"Altas",
"Emel",
""
],
[
"Tekin",
"Bayram",
""
]
] | We provide two novel ways to compute the surface gravity ($\kappa$) and the Hawking temperature $(T_{H})$ of a stationary black hole: in the first method $T_{H}$ is given as the three-volume integral of the Gauss-Bonnet invariant (or the Kretschmann scalar for Ricci-flat metrics) in the total region outside the event horizon; in the second method it is given as the surface integral of the Riemann tensor contracted with the covariant derivative of a Killing vector on the event horizon. To arrive at these new formulas for the black hole temperature (and the related surface gravity), we first construct a new differential geometric identity using the Bianchi identity and an antisymmetric rank-$2$ tensor, valid for spacetimes with at least one Killing vector field. The Gauss-Bonnet tensor and the Gauss-Bonnet scalar play a particular role in this geometric identity. We calculate the surface gravity and the Hawking temperature of the Kerr and the extremal Reissner-Nordstr\"om holes as examples. |
1812.02117 | Jose M. Carmona | J.L. Alonso and J.M. Carmona | Before spacetime: A proposal of a framework for multiverse quantum
cosmology based on three cosmological conjectures | 7 pages, 2 figures. Final version accepted for publication in CQG | Class. Quantum Grav. 36, 185001 (2019) | 10.1088/1361-6382/ab3780 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The three cosmological conjectures to which our work refers are: the
phenomenon called geodesic incompleteness, the physical gravitational
$\theta_G$-term that would characterize the 1-parameter family of inequivalent
vacua of quantum gravidynamics, and the hypothesis of multiversality, more
specifically, a zero-energy multiverse.
The known cosmological phenomenology leads under plausible assumptions to
theorems which establish that the universe is past incomplete. Here, starting
from Wilczek's definition of multiverse (a larger physical structure of which
the universe forms part) and that spacetime is much larger than the observable
universe, in a new sense suggested by these theorems, we place the observable
universe, labelled by $U_{\theta_G^{(1)}}$, within a multiverse ensemble,
$\{U_{\theta_G}\}$. Its topological $\theta_G^{(1)}$-term would characterize
the observable universe from the Planck epoch until the present time, and it
could have physical effects in, for example, black-hole physics.
Our proposal is therefore a possible framework for a multiverse quantum
cosmology, in which the temporal parameters (see figures in the main text)
start from a "timeless multiverse big bang" (TLMBB), where all members of the
multiverse ensemble, $\{U_{\theta_G}\}$, disappear, together with their
corresponding classical spacetimes. Since quantum cosmology can be viewed as
one attempt among many to face with the question of finding a gravitational
quantum theory, if the TLMBB were the appropriate ground to define the physical
or mathematical underlying structure of quantum cosmology, then multiversality
could come to have a predictive power within our observable universe.
| [
{
"created": "Wed, 5 Dec 2018 17:14:14 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jul 2019 11:23:02 GMT",
"version": "v2"
}
] | 2020-03-24 | [
[
"Alonso",
"J. L.",
""
],
[
"Carmona",
"J. M.",
""
]
] | The three cosmological conjectures to which our work refers are: the phenomenon called geodesic incompleteness, the physical gravitational $\theta_G$-term that would characterize the 1-parameter family of inequivalent vacua of quantum gravidynamics, and the hypothesis of multiversality, more specifically, a zero-energy multiverse. The known cosmological phenomenology leads under plausible assumptions to theorems which establish that the universe is past incomplete. Here, starting from Wilczek's definition of multiverse (a larger physical structure of which the universe forms part) and that spacetime is much larger than the observable universe, in a new sense suggested by these theorems, we place the observable universe, labelled by $U_{\theta_G^{(1)}}$, within a multiverse ensemble, $\{U_{\theta_G}\}$. Its topological $\theta_G^{(1)}$-term would characterize the observable universe from the Planck epoch until the present time, and it could have physical effects in, for example, black-hole physics. Our proposal is therefore a possible framework for a multiverse quantum cosmology, in which the temporal parameters (see figures in the main text) start from a "timeless multiverse big bang" (TLMBB), where all members of the multiverse ensemble, $\{U_{\theta_G}\}$, disappear, together with their corresponding classical spacetimes. Since quantum cosmology can be viewed as one attempt among many to face with the question of finding a gravitational quantum theory, if the TLMBB were the appropriate ground to define the physical or mathematical underlying structure of quantum cosmology, then multiversality could come to have a predictive power within our observable universe. |
1501.03556 | Xu Wei | Wei Xu, Jia Wang and Xin-he Meng | Entropy relations and the application of black holes with cosmological
constant and Gauss-Bonnet term | 12 pages, 0 figures, references added. Accepted for publication in
Physics Letters B | Physics Letters B 742 (2015) 225-230 | 10.1016/j.physletb.2015.01.018. | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on the entropy relations, we derive thermodynamic bound for entropy and
area of horizons of Schwarzschild-dS black hole, including the event horizon,
Cauchy horizon and negative horizon (i.e. the horizon with negative value),
which are all geometrical bound and made up of the cosmological radius.
Consider the first derivative of entropy relations together, we get the first
law of thermodynamics for all horizons. We also obtain the Smarr relation of
horizons by using the scaling discussion. For thermodynamics of all horizons,
the cosmological constant is treated as a thermodynamical variable. Especially
for thermodynamics of negative horizon, it is defined well in the $r<0$ side of
spacetime. The validity of this formula seems to work well for three-horizons
black holes. We also generalize the discussion to thermodynamics for event
horizon and Cauchy horizon of Gauss-Bonnet charged flat black holes, as the
Gauss-Bonnet coupling constant is also considered as thermodynamical variable.
These give further clue on the crucial role that the entropy relations of
multi-horizons play in black hole thermodynamics and understanding the entropy
at the microscopic level.
| [
{
"created": "Thu, 15 Jan 2015 02:24:54 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Feb 2015 13:37:45 GMT",
"version": "v2"
}
] | 2015-02-04 | [
[
"Xu",
"Wei",
""
],
[
"Wang",
"Jia",
""
],
[
"Meng",
"Xin-he",
""
]
] | Based on the entropy relations, we derive thermodynamic bound for entropy and area of horizons of Schwarzschild-dS black hole, including the event horizon, Cauchy horizon and negative horizon (i.e. the horizon with negative value), which are all geometrical bound and made up of the cosmological radius. Consider the first derivative of entropy relations together, we get the first law of thermodynamics for all horizons. We also obtain the Smarr relation of horizons by using the scaling discussion. For thermodynamics of all horizons, the cosmological constant is treated as a thermodynamical variable. Especially for thermodynamics of negative horizon, it is defined well in the $r<0$ side of spacetime. The validity of this formula seems to work well for three-horizons black holes. We also generalize the discussion to thermodynamics for event horizon and Cauchy horizon of Gauss-Bonnet charged flat black holes, as the Gauss-Bonnet coupling constant is also considered as thermodynamical variable. These give further clue on the crucial role that the entropy relations of multi-horizons play in black hole thermodynamics and understanding the entropy at the microscopic level. |
0803.0334 | David Brown | J. David Brown | Strongly Hyperbolic Extensions of the ADM Hamiltonian | This version contains minor corrections and clarifications. The
format has been changed to conform with IOP style | null | 10.1007/978-0-387-87499-9_6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The ADM Hamiltonian formulation of general relativity with prescribed lapse
and shift is a weakly hyperbolic system of partial differential equations. In
general weakly hyperbolic systems are not mathematically well posed. For well
posedness, the theory should be reformulated so that the complete system,
evolution equations plus gauge conditions, is (at least) strongly hyperbolic.
Traditionally, reformulation has been carried out at the level of equations of
motion. This typically destroys the variational and Hamiltonian structures of
the theory. Here I show that one can extend the ADM formalism to (i)
incorporate the gauge conditions as dynamical equations and (ii) affect the
hyperbolicity of the complete system, all while maintaining a Hamiltonian
description. The extended ADM formulation is used to obtain a strongly
hyperbolic Hamiltonian description of Einstein's theory that is generally
covariant under spatial diffeomorphisms and time reparametrizations, and has
physical characteristics. The extended Hamiltonian formulation with 1+log
slicing and gamma--driver shift conditions is weakly hyperbolic.
| [
{
"created": "Mon, 3 Mar 2008 21:29:44 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Jul 2008 19:01:01 GMT",
"version": "v2"
}
] | 2015-05-13 | [
[
"Brown",
"J. David",
""
]
] | The ADM Hamiltonian formulation of general relativity with prescribed lapse and shift is a weakly hyperbolic system of partial differential equations. In general weakly hyperbolic systems are not mathematically well posed. For well posedness, the theory should be reformulated so that the complete system, evolution equations plus gauge conditions, is (at least) strongly hyperbolic. Traditionally, reformulation has been carried out at the level of equations of motion. This typically destroys the variational and Hamiltonian structures of the theory. Here I show that one can extend the ADM formalism to (i) incorporate the gauge conditions as dynamical equations and (ii) affect the hyperbolicity of the complete system, all while maintaining a Hamiltonian description. The extended ADM formulation is used to obtain a strongly hyperbolic Hamiltonian description of Einstein's theory that is generally covariant under spatial diffeomorphisms and time reparametrizations, and has physical characteristics. The extended Hamiltonian formulation with 1+log slicing and gamma--driver shift conditions is weakly hyperbolic. |
1610.07069 | Ali \"Ovg\"un | Kimet Jusufi and Ali \"Ovg\"un | Hawking radiation of scalar and vector particles from 5D Myers-Perry
black holes | 11 pages, Accepted for publication in International Journal of
Theoretical Physics | Int J Theor Phys (2017) 56: 1725 | 10.1007/s10773-017-3317-7 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present paper we explore the Hawking radiation as a quantum tunneling
effect from a rotating 5 dimensional Myers-Perry black hole (5D-MPBH) with two
independent angular momentum components. First, we investigate the Hawking
temperature by considering the tunneling of massive scalar particles and spin-1
vector particles from the 5D-MPBH in the Painlev\'{e} coordinates and then in
the corotating frames. More specifically, we solve the Klein-Gordon and Proca
equations by applying the WKB method and Hamilton-Jacobi equation in both
cases. Finally, we recover the Hawking temperature and show that coordinates
systems do not affect the Hawking temperature.
| [
{
"created": "Sat, 22 Oct 2016 16:08:45 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Feb 2017 10:49:37 GMT",
"version": "v2"
}
] | 2017-05-12 | [
[
"Jusufi",
"Kimet",
""
],
[
"Övgün",
"Ali",
""
]
] | In the present paper we explore the Hawking radiation as a quantum tunneling effect from a rotating 5 dimensional Myers-Perry black hole (5D-MPBH) with two independent angular momentum components. First, we investigate the Hawking temperature by considering the tunneling of massive scalar particles and spin-1 vector particles from the 5D-MPBH in the Painlev\'{e} coordinates and then in the corotating frames. More specifically, we solve the Klein-Gordon and Proca equations by applying the WKB method and Hamilton-Jacobi equation in both cases. Finally, we recover the Hawking temperature and show that coordinates systems do not affect the Hawking temperature. |
1907.06332 | Qing-Hua Zhu | Zhe Chang and Qing-Hua Zhu | Redshift drift in uniformly accelerated reference frame | v1: 28 pages, 4 figures; v2: 29 pages, 4 figures. Published in
Chinese Physics C | Chinese Physics C, Vol. 44. No. 7 (2020) 075103 | 10.1088/1674-1137/44/7/075103 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct an alternative uniformly accelerated reference frame based on
the 3+1 formalism in adapted coordinates. In this frame, time-dependent
redshift drift exists between co-moving observers, which differs from that in
Rindler coordinates. This phenomenon can be tested in laboratory and improve
our understanding of non-inertial frames.
| [
{
"created": "Mon, 15 Jul 2019 05:01:46 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Jul 2020 03:58:46 GMT",
"version": "v2"
}
] | 2020-07-03 | [
[
"Chang",
"Zhe",
""
],
[
"Zhu",
"Qing-Hua",
""
]
] | We construct an alternative uniformly accelerated reference frame based on the 3+1 formalism in adapted coordinates. In this frame, time-dependent redshift drift exists between co-moving observers, which differs from that in Rindler coordinates. This phenomenon can be tested in laboratory and improve our understanding of non-inertial frames. |
1005.0062 | Hossein Farajollahi | H.Farajollahi, N. Mohamadi, H. Amiri | Interacting Cosmic Fluids in Brans-Dicke Cosmology | 13 pages, 8 figures | Mod. Phys. Lett. A, 25, No. 30 (2010) 2579-2589 | 10.1142/S0217732310033499 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a detailed description for power-law scaling FRW cosmological
models in Brans-Dicke theory dominated by two interacting fluid components
during the expansion of the universe.
| [
{
"created": "Sat, 1 May 2010 10:45:02 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Jun 2011 07:14:05 GMT",
"version": "v2"
}
] | 2015-05-18 | [
[
"Farajollahi",
"H.",
""
],
[
"Mohamadi",
"N.",
""
],
[
"Amiri",
"H.",
""
]
] | We provide a detailed description for power-law scaling FRW cosmological models in Brans-Dicke theory dominated by two interacting fluid components during the expansion of the universe. |
1602.00106 | Madhavan Varadarajan | Madhavan Varadarajan | A Note on Entanglement Entropy, Coherent States and Gravity | 16 pages, no figures, 3 paragraphs added to last section in response
to referee comments, to appear as Editor's Choice Article in `General
Relativity and Gravitation' | null | 10.1007/s10714-016-2030-9 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The entanglement entropy of a free quantum field in a coherent state is
independent of its stress energy content. We use this result to highlight the
fact that while the Einstein equations for first order variations about a
locally maximally symmetric vacuum state of geometry and quantum fields seem to
follow from Jacobson's principle of maximal vacuum entanglement entropy, their
possible derivation from this principle for the physically relevant case of
finite but small variations remains an open issue. We also apply this result to
the context of Bianchi's identification, independent of unknown Planck scale
physics, of the first order variation of Bekenstein Hawking area with that of
vacuum entanglement entropy. We argue that under certain technical assumptions
this identification seems not to be extendible to the context of finite but
small variations to coherent states. Our particular method of estimation of
entanglement entropy variation reveals the existence of certain contributions
over and above those appearing in Jacobson's and Bianchi's works. We discuss
the sense in which these contributions may be subleading to those already
present in these works.
| [
{
"created": "Sat, 30 Jan 2016 11:36:08 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Feb 2016 05:07:20 GMT",
"version": "v2"
}
] | 2016-02-19 | [
[
"Varadarajan",
"Madhavan",
""
]
] | The entanglement entropy of a free quantum field in a coherent state is independent of its stress energy content. We use this result to highlight the fact that while the Einstein equations for first order variations about a locally maximally symmetric vacuum state of geometry and quantum fields seem to follow from Jacobson's principle of maximal vacuum entanglement entropy, their possible derivation from this principle for the physically relevant case of finite but small variations remains an open issue. We also apply this result to the context of Bianchi's identification, independent of unknown Planck scale physics, of the first order variation of Bekenstein Hawking area with that of vacuum entanglement entropy. We argue that under certain technical assumptions this identification seems not to be extendible to the context of finite but small variations to coherent states. Our particular method of estimation of entanglement entropy variation reveals the existence of certain contributions over and above those appearing in Jacobson's and Bianchi's works. We discuss the sense in which these contributions may be subleading to those already present in these works. |
2301.10215 | Edward Wilson-Ewing | Ivan Agullo, Anzhong Wang, Edward Wilson-Ewing | Loop quantum cosmology: relation between theory and observations | 47 pages, 2 figures, to be published in Handbook of Quantum Gravity
(Eds. C. Bambi, L. Modesto and I.L. Shapiro, Springer, expected 2023) | null | 10.1007/978-981-19-3079-9_103-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This chapter provides a review of the frameworks developed for cosmological
perturbation theory in loop quantum cosmology, and applications to various
models of the early universe including inflation, ekpyrosis and the matter
bounce, with an emphasis on potential observational consequences. It also
includes a discussion on extensions to include non-Gaussianities and background
anisotropies, as well as on its limitations concerning trans-Planckian
perturbations and quantization ambiguities. It concludes with a summary of
recent work studying the relation between loop quantum cosmology and full loop
quantum gravity.
| [
{
"created": "Tue, 24 Jan 2023 18:44:26 GMT",
"version": "v1"
}
] | 2024-03-08 | [
[
"Agullo",
"Ivan",
""
],
[
"Wang",
"Anzhong",
""
],
[
"Wilson-Ewing",
"Edward",
""
]
] | This chapter provides a review of the frameworks developed for cosmological perturbation theory in loop quantum cosmology, and applications to various models of the early universe including inflation, ekpyrosis and the matter bounce, with an emphasis on potential observational consequences. It also includes a discussion on extensions to include non-Gaussianities and background anisotropies, as well as on its limitations concerning trans-Planckian perturbations and quantization ambiguities. It concludes with a summary of recent work studying the relation between loop quantum cosmology and full loop quantum gravity. |
gr-qc/0610122 | Gregory B. Cook | Alessandra Buonanno, Gregory B. Cook, Frans Pretorius | Inspiral, merger and ring-down of equal-mass black-hole binaries | 47 pages, 34 figures, full abstract in paper, revtex4, accepted by
PRD, miscellaneous revisions throughout paper | Phys.Rev.D75:124018,2007 | 10.1103/PhysRevD.75.124018 | null | gr-qc astro-ph | null | We investigate the dynamics and gravitational-wave (GW) emission in the
binary merger of equal-mass black holes as obtained from numerical relativity
simulations. Results from the evolution of three sets of initial data are
explored in detail, corresponding to different initial separations of the black
holes. We find that to a good approximation the inspiral phase of the evolution
is quasi-circular, followed by a "blurred, quasi-circular plunge", then merger
and ring down. We present first-order comparisons between analytical models of
the various stages of the merger and the numerical results. We provide
comparisons between the numerical results and analytical predictions based on
the adiabatic Newtonain, post-Newtonian (PN), and non-adiabatic resummed-PN
models. From the ring-down portion of the GW we extract the fundamental
quasi-normal mode and several of the overtones. Finally, we estimate the
optimal signal-to-noise ratio for typical binaries detectable by GW
experiments.
| [
{
"created": "Wed, 25 Oct 2006 18:27:10 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Jun 2007 20:25:08 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Buonanno",
"Alessandra",
""
],
[
"Cook",
"Gregory B.",
""
],
[
"Pretorius",
"Frans",
""
]
] | We investigate the dynamics and gravitational-wave (GW) emission in the binary merger of equal-mass black holes as obtained from numerical relativity simulations. Results from the evolution of three sets of initial data are explored in detail, corresponding to different initial separations of the black holes. We find that to a good approximation the inspiral phase of the evolution is quasi-circular, followed by a "blurred, quasi-circular plunge", then merger and ring down. We present first-order comparisons between analytical models of the various stages of the merger and the numerical results. We provide comparisons between the numerical results and analytical predictions based on the adiabatic Newtonain, post-Newtonian (PN), and non-adiabatic resummed-PN models. From the ring-down portion of the GW we extract the fundamental quasi-normal mode and several of the overtones. Finally, we estimate the optimal signal-to-noise ratio for typical binaries detectable by GW experiments. |
2008.12109 | Pujian Mao | Pujian Mao | Remarks on infinite towers of gravitational memories | v2: minor revision, several issues clarified, typos corrected, refs.
added | JHEP 11 (2020) 102 | 10.1007/JHEP11(2020)102 | CJQS-2020-034 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An infinite tower of gravitational memories was proposed in
\cite{Compere:2019odm} by considering the matter-induced vacuum transition in
the impulsive limit. We give an alternative realization of the infinite towers
of gravitational memories in Newman-Penrose formalism. We also demonstrate that
the memories at each order can be associated to the same supertranslation
instead of infinite towers of supertranslations or superrotations.
| [
{
"created": "Thu, 27 Aug 2020 13:35:09 GMT",
"version": "v1"
},
{
"created": "Sat, 21 Nov 2020 13:14:02 GMT",
"version": "v2"
}
] | 2020-11-24 | [
[
"Mao",
"Pujian",
""
]
] | An infinite tower of gravitational memories was proposed in \cite{Compere:2019odm} by considering the matter-induced vacuum transition in the impulsive limit. We give an alternative realization of the infinite towers of gravitational memories in Newman-Penrose formalism. We also demonstrate that the memories at each order can be associated to the same supertranslation instead of infinite towers of supertranslations or superrotations. |
2106.02414 | Angela Borchers | Angela Borchers and Frank Ohme | Black-hole kicks: a tool to measure the accuracy of gravitational-wave
models | Contribution to the 2021 Gravitation session of the 55th Rencontres
de Moriond | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | Asymmetric binary systems radiate linear momentum through gravitational
waves, leading to the recoil of the merger remnant. Black-hole kicks have
attracted much attention because of their astrophysical implications. However,
little information can be extracted from the observations made by LIGO and
Virgo so far. In this work, we discuss how the gravitational recoil, an effect
that is encoded in the gravitational signal, can be used to test the accuracy
of waveform models. Gravitational-wave models of merging binary systems have
become fundamental to detect potential signals and infer the parameters of
observed sources. But, as the interferometers' sensitivity is enhanced in
current and future detectors, gravitational waveform models will have to be
further improved. We find that the kick is highly sensitive to waveform
inaccuracies and can therefore be a useful diagnostic test. Furthermore, we
observe that current higher-mode waveform models are not consistent in their
kick predictions. For this reason, we discuss whether measuring and improving
waveform accuracy can, in turn, allow us to extract meaningful information
about the kick in future observations.
| [
{
"created": "Fri, 4 Jun 2021 11:14:50 GMT",
"version": "v1"
}
] | 2021-06-07 | [
[
"Borchers",
"Angela",
""
],
[
"Ohme",
"Frank",
""
]
] | Asymmetric binary systems radiate linear momentum through gravitational waves, leading to the recoil of the merger remnant. Black-hole kicks have attracted much attention because of their astrophysical implications. However, little information can be extracted from the observations made by LIGO and Virgo so far. In this work, we discuss how the gravitational recoil, an effect that is encoded in the gravitational signal, can be used to test the accuracy of waveform models. Gravitational-wave models of merging binary systems have become fundamental to detect potential signals and infer the parameters of observed sources. But, as the interferometers' sensitivity is enhanced in current and future detectors, gravitational waveform models will have to be further improved. We find that the kick is highly sensitive to waveform inaccuracies and can therefore be a useful diagnostic test. Furthermore, we observe that current higher-mode waveform models are not consistent in their kick predictions. For this reason, we discuss whether measuring and improving waveform accuracy can, in turn, allow us to extract meaningful information about the kick in future observations. |
2406.02621 | Puskar Mondal | Puskar Mondal, Shing-Tung Yau | A new conformal quasi-local energy in general relativity | comments welcome. arXiv admin note: text overlap with
arXiv:2401.13909 | null | null | null | gr-qc math-ph math.DG math.MP | http://creativecommons.org/licenses/by/4.0/ | We construct new conserved quasi-local energies in general relativity using
the formalism developed by \cite{CWY}. In particular, we use the optimal
isometric embedding defined in \cite{yau,yau1} to transplant the conformal
Killing fields of the Minkowski space back to the $ 2-$ surface of interest in
the physical spacetime. For an asymptotically flat spacetime of order $1$, we
show that these energies are always finite. Their limit as the total energies
of an isolated system is evaluated and a conservation law under Einsteinian
evolution is deduced.
| [
{
"created": "Mon, 3 Jun 2024 19:11:12 GMT",
"version": "v1"
}
] | 2024-06-06 | [
[
"Mondal",
"Puskar",
""
],
[
"Yau",
"Shing-Tung",
""
]
] | We construct new conserved quasi-local energies in general relativity using the formalism developed by \cite{CWY}. In particular, we use the optimal isometric embedding defined in \cite{yau,yau1} to transplant the conformal Killing fields of the Minkowski space back to the $ 2-$ surface of interest in the physical spacetime. For an asymptotically flat spacetime of order $1$, we show that these energies are always finite. Their limit as the total energies of an isolated system is evaluated and a conservation law under Einsteinian evolution is deduced. |
0806.4710 | Eugenio Bianchi | Eugenio Bianchi | The length operator in Loop Quantum Gravity | 33 pages, 12 figures; NPB version | Nucl.Phys.B807:591-624,2009 | 10.1016/j.nuclphysb.2008.08.013 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The dual picture of quantum geometry provided by a spin network state is
discussed. From this perspective, we introduce a new operator in Loop Quantum
Gravity - the length operator. We describe its quantum geometrical meaning and
derive some of its properties. In particular we show that the operator has a
discrete spectrum and is diagonalized by appropriate superpositions of spin
network states. A series of eigenstates and eigenvalues is presented and an
explicit check of its semiclassical properties is discussed.
| [
{
"created": "Sat, 28 Jun 2008 17:44:42 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Sep 2008 13:24:29 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Bianchi",
"Eugenio",
""
]
] | The dual picture of quantum geometry provided by a spin network state is discussed. From this perspective, we introduce a new operator in Loop Quantum Gravity - the length operator. We describe its quantum geometrical meaning and derive some of its properties. In particular we show that the operator has a discrete spectrum and is diagonalized by appropriate superpositions of spin network states. A series of eigenstates and eigenvalues is presented and an explicit check of its semiclassical properties is discussed. |
1108.3114 | Ting Hong | T. Hong, J. Miller, H. Yamamoto, Y. Chen, R. Adhikari | Effects of Mirror Aberrations on Laguerre-Gaussian Beams in
Interferometric Gravitational-Wave Detectors | 10 pages, 11 figures | null | 10.1103/PhysRevD.84.102001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A fundamental limit to the sensitivity of optical interferometers is imposed
by Brownian thermal fluctuations of the mirrors' surfaces. This thermal noise
can be reduced by using larger beams which "average out" the random
fluctuations of the surfaces. It has been proposed previously that wider,
higher-order Laguerre-Gaussian modes can be used to exploit this effect. In
this article, we show that susceptibility to spatial imperfections of the
mirrors' surfaces limits the effectiveness of this approach in interferometers
used for gravitational-wave detection. Possible methods of reducing this
susceptibility are also discussed.
| [
{
"created": "Mon, 15 Aug 2011 22:54:51 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Aug 2011 22:37:46 GMT",
"version": "v2"
},
{
"created": "Wed, 12 Oct 2011 22:55:35 GMT",
"version": "v3"
}
] | 2013-05-29 | [
[
"Hong",
"T.",
""
],
[
"Miller",
"J.",
""
],
[
"Yamamoto",
"H.",
""
],
[
"Chen",
"Y.",
""
],
[
"Adhikari",
"R.",
""
]
] | A fundamental limit to the sensitivity of optical interferometers is imposed by Brownian thermal fluctuations of the mirrors' surfaces. This thermal noise can be reduced by using larger beams which "average out" the random fluctuations of the surfaces. It has been proposed previously that wider, higher-order Laguerre-Gaussian modes can be used to exploit this effect. In this article, we show that susceptibility to spatial imperfections of the mirrors' surfaces limits the effectiveness of this approach in interferometers used for gravitational-wave detection. Possible methods of reducing this susceptibility are also discussed. |
gr-qc/9907058 | Jerzy Lewandowski | Jerzy Lewandowski (Warsaw) | Space-Times Admitting Isolated Horizons | 11 pages, no figures | Class.Quant.Grav.17:L53-L59,2000 | 10.1088/0264-9381/17/4/101 | null | gr-qc astro-ph hep-th | null | We characterize a general solution to the vacuum Einstein equations which
admits isolated horizons. We show it is a non-linear superposition -- in
precise sense -- of the Schwarzschild metric with a certain free data set
propagating tangentially to the horizon. This proves Ashtekar's conjecture
about the structure of spacetime near the isolated horizon. The same
superposition method applied to the Kerr metric gives another class of vacuum
solutions admitting isolated horizons. More generally, a vacuum spacetime
admitting any null, non expanding, shear free surface is characterized. The
results are applied to show that, generically, the non-rotating isolated
horizon does not admit a Killing vector field and a spacetime is not
spherically symmetric near a symmetric horizon.
| [
{
"created": "Mon, 19 Jul 1999 19:18:16 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Jan 2000 14:47:02 GMT",
"version": "v2"
}
] | 2010-04-06 | [
[
"Lewandowski",
"Jerzy",
"",
"Warsaw"
]
] | We characterize a general solution to the vacuum Einstein equations which admits isolated horizons. We show it is a non-linear superposition -- in precise sense -- of the Schwarzschild metric with a certain free data set propagating tangentially to the horizon. This proves Ashtekar's conjecture about the structure of spacetime near the isolated horizon. The same superposition method applied to the Kerr metric gives another class of vacuum solutions admitting isolated horizons. More generally, a vacuum spacetime admitting any null, non expanding, shear free surface is characterized. The results are applied to show that, generically, the non-rotating isolated horizon does not admit a Killing vector field and a spacetime is not spherically symmetric near a symmetric horizon. |
1512.04064 | Pisin Chen | Pisin Chen and Gerard Mourou | Accelerating Plasma Mirrors to Investigate Black Hole Information Loss
Paradox | 5 pages, 2 figures | Phys. Rev. Lett. 118, 045001 (2017) | 10.1103/PhysRevLett.118.045001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The question of whether Hawking evaporation violates unitarity, and therefore
results in the loss of information, remains unresolved since Hawking's seminal
discovery. So far the investigations remain mostly theoretical since it is
almost impossible to settle this paradox through direct astrophysical black
hole observations. Here we point out that relativistic plasma mirrors can be
accelerated drastically and stopped abruptly by impinging ultra intense x-ray
pulses on solid plasma targets with a density gradient. This is analogous to
the late time evolution of black hole Hawking evaporation. A conception of such
an experiment is proposed and a self-consistent set of physical parameters is
presented. Critical issues such as black hole unitarity may be addressed
through the measurement of the entanglement between the Hawking radiation and
their partner modes.
| [
{
"created": "Sun, 13 Dec 2015 15:15:26 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Dec 2015 20:05:07 GMT",
"version": "v2"
},
{
"created": "Sun, 28 Feb 2016 08:42:28 GMT",
"version": "v3"
},
{
"created": "Fri, 22 Jul 2016 21:31:57 GMT",
"version": "v4"
},
{
"created": "Sun, 25 Dec 2016 22:35:41 GMT",
"version": "v5"
}
] | 2017-02-01 | [
[
"Chen",
"Pisin",
""
],
[
"Mourou",
"Gerard",
""
]
] | The question of whether Hawking evaporation violates unitarity, and therefore results in the loss of information, remains unresolved since Hawking's seminal discovery. So far the investigations remain mostly theoretical since it is almost impossible to settle this paradox through direct astrophysical black hole observations. Here we point out that relativistic plasma mirrors can be accelerated drastically and stopped abruptly by impinging ultra intense x-ray pulses on solid plasma targets with a density gradient. This is analogous to the late time evolution of black hole Hawking evaporation. A conception of such an experiment is proposed and a self-consistent set of physical parameters is presented. Critical issues such as black hole unitarity may be addressed through the measurement of the entanglement between the Hawking radiation and their partner modes. |
gr-qc/0609028 | Scott A. Hughes | Scott A. Hughes | A brief survey of LISA sources and science | 8 pages, 2 figures, for the Proceedings of the Sixth International
LISA Symposium. Particularly silly typo in one equation fixed | null | 10.1063/1.2405017 | null | gr-qc astro-ph | null | LISA is a planned space-based gravitational-wave (GW) detector that would be
sensitive to waves from low-frequency sources, in the band of roughly $(0.03 -
0.1) {\rm mHz} \lesssim f \lesssim 0.1 {\rm Hz}$. This is expected to be an
extremely rich chunk of the GW spectrum -- observing these waves will provide a
unique view of dynamical processes in astrophysics. Here we give a quick survey
of some key LISA sources and what GWs can uniquely teach us about these
sources. Particularly noteworthy science which is highlighted here is the
potential for LISA to track the moderate to high redshift evolution of black
hole masses and spins through the measurement of GWs generated from massive
black hole binaries (which in turn form by the merger of galaxies and
protogalaxies). Measurement of these binary black hole waves has the potential
to determine the masses and spins of the constituent black holes with
percent-level accuracy or better, providing a unique high-precision probe of an
aspect of early structure growth. This article is based on the ``Astrophysics
Tutorial'' talk given by the author at the Sixth International LISA Symposium.
| [
{
"created": "Thu, 7 Sep 2006 18:19:05 GMT",
"version": "v1"
},
{
"created": "Sun, 10 Sep 2006 01:28:01 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Hughes",
"Scott A.",
""
]
] | LISA is a planned space-based gravitational-wave (GW) detector that would be sensitive to waves from low-frequency sources, in the band of roughly $(0.03 - 0.1) {\rm mHz} \lesssim f \lesssim 0.1 {\rm Hz}$. This is expected to be an extremely rich chunk of the GW spectrum -- observing these waves will provide a unique view of dynamical processes in astrophysics. Here we give a quick survey of some key LISA sources and what GWs can uniquely teach us about these sources. Particularly noteworthy science which is highlighted here is the potential for LISA to track the moderate to high redshift evolution of black hole masses and spins through the measurement of GWs generated from massive black hole binaries (which in turn form by the merger of galaxies and protogalaxies). Measurement of these binary black hole waves has the potential to determine the masses and spins of the constituent black holes with percent-level accuracy or better, providing a unique high-precision probe of an aspect of early structure growth. This article is based on the ``Astrophysics Tutorial'' talk given by the author at the Sixth International LISA Symposium. |
0905.3120 | Chris Pankow | C. Pankow, S. Klimenko, G. Mitselmakher, I. Yakushin, G. Vedovato, M.
Drago, R. A. Mercer and P. Ajith | A burst search for gravitational waves from binary black holes | 12 pages, 4 figures, 2 tables, submitted for publication in CQG in
the special issue for the conference proceedings of GWDAW13; corrected some
typos, addressed some minor reviewer comments one section restructured and
references updated and corrected | null | 10.1088/0264-9381/26/20/204004 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Compact binary coalescence (CBC) is one of the most promising sources of
gravitational waves. These sources are usually searched for with matched
filters which require accurate calculation of the GW waveforms and generation
of large template banks. We present a complementary search technique based on
algorithms used in un-modeled searches. Initially designed for detection of
un-modeled bursts, which can span a very large set of waveform morphologies,
the search algorithm presented here is constrained for targeted detection of
the smaller subset of CBC signals. The constraint is based on the assumption of
elliptical polarisation for signals received at the detector. We expect that
the algorithm is sensitive to CBC signals in a wide range of masses, mass
ratios, and spin parameters. In preparation for the analysis of data from the
fifth LIGO-Virgo science run (S5), we performed preliminary studies of the
algorithm on test data. We present the sensitivity of the search to different
types of simulated CBC waveforms. Also, we discuss how to extend the results of
the test run into a search over all of the current LIGO-Virgo data set.
| [
{
"created": "Tue, 19 May 2009 14:57:06 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Aug 2009 15:10:33 GMT",
"version": "v2"
}
] | 2015-05-13 | [
[
"Pankow",
"C.",
""
],
[
"Klimenko",
"S.",
""
],
[
"Mitselmakher",
"G.",
""
],
[
"Yakushin",
"I.",
""
],
[
"Vedovato",
"G.",
""
],
[
"Drago",
"M.",
""
],
[
"Mercer",
"R. A.",
""
],
[
"Ajith",
"P.",
""
]
] | Compact binary coalescence (CBC) is one of the most promising sources of gravitational waves. These sources are usually searched for with matched filters which require accurate calculation of the GW waveforms and generation of large template banks. We present a complementary search technique based on algorithms used in un-modeled searches. Initially designed for detection of un-modeled bursts, which can span a very large set of waveform morphologies, the search algorithm presented here is constrained for targeted detection of the smaller subset of CBC signals. The constraint is based on the assumption of elliptical polarisation for signals received at the detector. We expect that the algorithm is sensitive to CBC signals in a wide range of masses, mass ratios, and spin parameters. In preparation for the analysis of data from the fifth LIGO-Virgo science run (S5), we performed preliminary studies of the algorithm on test data. We present the sensitivity of the search to different types of simulated CBC waveforms. Also, we discuss how to extend the results of the test run into a search over all of the current LIGO-Virgo data set. |
0910.5659 | Jaakko Vainio | Tuomas Multam\"aki, Jaakko Vainio, Iiro Vilja | Hamiltonian perturbation theory in f(R) gravity | 16 pages | Phys.Rev.D81:064025,2010 | 10.1103/PhysRevD.81.064025 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Hamiltonian perturbation theory is used to analyse the stability of f(R)
models. The Hamiltonian equations for the metric and its momentum conjugate are
written for f(R) Lagrangian in the presence of perfect fluid matter. The
perturbations examined are perpendicular to R. As perturbations are added to
the metric and momentum conjugate to the induced metric instabilities are
found, depending on the form of f(R). Thus the examination of these
instabilities is a way to rule out certain f(R) models.
| [
{
"created": "Thu, 29 Oct 2009 15:07:13 GMT",
"version": "v1"
}
] | 2010-04-29 | [
[
"Multamäki",
"Tuomas",
""
],
[
"Vainio",
"Jaakko",
""
],
[
"Vilja",
"Iiro",
""
]
] | Hamiltonian perturbation theory is used to analyse the stability of f(R) models. The Hamiltonian equations for the metric and its momentum conjugate are written for f(R) Lagrangian in the presence of perfect fluid matter. The perturbations examined are perpendicular to R. As perturbations are added to the metric and momentum conjugate to the induced metric instabilities are found, depending on the form of f(R). Thus the examination of these instabilities is a way to rule out certain f(R) models. |
1805.07818 | Kalin Staykov | Kalin V. Staykov, Dimitar Popchev, Daniela D. Doneva, Stoytcho S.
Yazadjiev | Static and slowly rotating neutron stars in scalar-tensor theory with
self-interacting massive scalar field | 9 pages, 5 figures | null | 10.1140/epjc/s10052-018-6064-x | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Binary pulsar observations and gravitational wave detections seriously
constrained scalar-tensor theories with massless scalar field allowing only
small deviations from general relativity. If we consider a nonzero mass of the
scalar field, though, significant deviations from general relativity are
allowed for values of the parameters that are in agreement with the
observations. In the present paper we extend this idea and we study
scalar-tensor theory with massive field with self-interaction term in the
potential. The additional term suppresses the scalar field in the neutron star
models in addition to the effect of the mass of the scalar field but still,
large deviations from pure GR can be observed for values of the parameters that
are in agreement with the observations.
| [
{
"created": "Sun, 20 May 2018 19:59:57 GMT",
"version": "v1"
}
] | 2018-08-15 | [
[
"Staykov",
"Kalin V.",
""
],
[
"Popchev",
"Dimitar",
""
],
[
"Doneva",
"Daniela D.",
""
],
[
"Yazadjiev",
"Stoytcho S.",
""
]
] | Binary pulsar observations and gravitational wave detections seriously constrained scalar-tensor theories with massless scalar field allowing only small deviations from general relativity. If we consider a nonzero mass of the scalar field, though, significant deviations from general relativity are allowed for values of the parameters that are in agreement with the observations. In the present paper we extend this idea and we study scalar-tensor theory with massive field with self-interaction term in the potential. The additional term suppresses the scalar field in the neutron star models in addition to the effect of the mass of the scalar field but still, large deviations from pure GR can be observed for values of the parameters that are in agreement with the observations. |
2211.10456 | Alejandro Aguilar-Nieto | Alejandro Aguilar-Nieto, V\'ictor Jaramillo, Juan Barranco, Argelia
Bernal, Juan Carlos Degollado, Dar\'io N\'u\~nez | Self-interacting scalar field distributions around Schwarzschild black
holes | 14 pages, 13 figures | null | 10.1103/PhysRevD.107.044070 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Long-lived configurations of massive scalar fields around black holes may
form if the coupling between the mass of the scalar field and the mass of the
black hole is very small. In this work we analyze the effect of
self-interaction in the distribution of the long-lived cloud surrounding a
static black hole. We consider both attractive and repulsive self-interactions.
By solving numerically the Klein Gordon equation on a fixed background in the
frequency domain, we find that the spatial distribution of quasi stationary
states may be larger as compared to the non interacting case. We performed a
time evolution to determine the effect of the self-interaction on the life time
of the configurations our findings indicate that the contribution of the
self-interaction is subdominant.
| [
{
"created": "Fri, 18 Nov 2022 19:00:08 GMT",
"version": "v1"
}
] | 2023-03-08 | [
[
"Aguilar-Nieto",
"Alejandro",
""
],
[
"Jaramillo",
"Víctor",
""
],
[
"Barranco",
"Juan",
""
],
[
"Bernal",
"Argelia",
""
],
[
"Degollado",
"Juan Carlos",
""
],
[
"Núñez",
"Darío",
""
]
] | Long-lived configurations of massive scalar fields around black holes may form if the coupling between the mass of the scalar field and the mass of the black hole is very small. In this work we analyze the effect of self-interaction in the distribution of the long-lived cloud surrounding a static black hole. We consider both attractive and repulsive self-interactions. By solving numerically the Klein Gordon equation on a fixed background in the frequency domain, we find that the spatial distribution of quasi stationary states may be larger as compared to the non interacting case. We performed a time evolution to determine the effect of the self-interaction on the life time of the configurations our findings indicate that the contribution of the self-interaction is subdominant. |
2212.04600 | Matthew Digman | Matthew C. Digman, Neil J. Cornish | Parameter Estimation for Stellar-Origin Black Hole Mergers In LISA | 13 pages, 6 figures, 1 table | null | 10.1103/PhysRevD.108.023022 | null | gr-qc astro-ph.HE astro-ph.IM | http://creativecommons.org/licenses/by-nc-sa/4.0/ | The population of stellar origin black hole binaries (SOBHBs) detected by
existing ground-based gravitational wave detectors is an exciting target for
the future space-based Laser Interferometer Space Antenna (LISA). LISA is
sensitive to signals at significantly lower frequencies than ground-based
detectors. SOBHB signals will thus be detected much earlier in their evolution,
years to decades before they merge. The mergers will then occur in the
frequency band covered by ground-based detectors. Observing SOBHBs years before
merger can help distinguish between progenitor models for these systems. We
present a new Bayesian parameter estimation algorithm for LISA observations of
SOBHBs that uses a time-frequency (wavelet) based likelihood function. Our
technique accelerates the analysis by several orders of magnitude compared to
the standard frequency domain approach and allows for an efficient treatment of
non-stationary noise.
| [
{
"created": "Thu, 8 Dec 2022 23:17:02 GMT",
"version": "v1"
}
] | 2023-08-09 | [
[
"Digman",
"Matthew C.",
""
],
[
"Cornish",
"Neil J.",
""
]
] | The population of stellar origin black hole binaries (SOBHBs) detected by existing ground-based gravitational wave detectors is an exciting target for the future space-based Laser Interferometer Space Antenna (LISA). LISA is sensitive to signals at significantly lower frequencies than ground-based detectors. SOBHB signals will thus be detected much earlier in their evolution, years to decades before they merge. The mergers will then occur in the frequency band covered by ground-based detectors. Observing SOBHBs years before merger can help distinguish between progenitor models for these systems. We present a new Bayesian parameter estimation algorithm for LISA observations of SOBHBs that uses a time-frequency (wavelet) based likelihood function. Our technique accelerates the analysis by several orders of magnitude compared to the standard frequency domain approach and allows for an efficient treatment of non-stationary noise. |
2302.02433 | Gholam Hossein Bordbar | H. Barzegar, M. Bigdeli, G. H. Bordbar, and B. Eslam Panah | Stable three-dimensional (un)charged AdS gravastars in gravity's rainbow | 21 pages, 17 figures | European Physical Journal C 83 (2023) 151 | 10.1140/epjc/s10052-023-11295-3 | null | gr-qc astro-ph.HE astro-ph.SR hep-th | http://creativecommons.org/licenses/by-nc-nd/4.0/ | In this work, we study the three-dimensional AdS gravitational vacuum stars
(gravastars) in the context of gravity's rainbow theory. Then we extend it by
adding the Maxwell electromagnetic field. We compute the physical features of
gravastars, such as proper length, energy, entropy, and junction conditions.
Our results show that the physical parameters for charged and uncharged states
depend significantly on rainbow functions. Besides from charged state, they
also depend on the electric field. Finally, we explore the stability of thin
shell of three-dimensional (un)charged AdS gravastars in gravity's rainbow. We
show that the structure of thin shell of these gravastars may be stable and is
independent of the type of matter.
| [
{
"created": "Sun, 5 Feb 2023 17:08:14 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Feb 2023 09:45:58 GMT",
"version": "v2"
}
] | 2023-02-17 | [
[
"Barzegar",
"H.",
""
],
[
"Bigdeli",
"M.",
""
],
[
"Bordbar",
"G. H.",
""
],
[
"Panah",
"B. Eslam",
""
]
] | In this work, we study the three-dimensional AdS gravitational vacuum stars (gravastars) in the context of gravity's rainbow theory. Then we extend it by adding the Maxwell electromagnetic field. We compute the physical features of gravastars, such as proper length, energy, entropy, and junction conditions. Our results show that the physical parameters for charged and uncharged states depend significantly on rainbow functions. Besides from charged state, they also depend on the electric field. Finally, we explore the stability of thin shell of three-dimensional (un)charged AdS gravastars in gravity's rainbow. We show that the structure of thin shell of these gravastars may be stable and is independent of the type of matter. |
1506.04685 | Mauricio Cataldo MC | Mauricio Cataldo, Luis Liempi, Pablo Rodriguez | Morris-Thorne wormholes in static pseudo-spherically symmetric
spacetimes | 12 pages, 5 figures | Phys. Rev. D 91, 124039 (2015) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we study classical general relativistic static wormhole
configurations with pseudo-spherical symmetry. We show that in addition to the
hyperbolic wormhole solutions discussed by Lobo and Mimoso in the Ref. Phys.\
Rev.\ D {\bf 82}, 044034 (2010), there exists another wormhole class, which is
truly pseudo-spherical counterpart of spherical Morris-Thorne wormhole
(contrary to the Lobo-Mimoso wormhole class), since all constraints originally
defined by Morris and Thorne for spherically symmetric wormholes are satisfied.
We show that, for both classes of hyperbolic wormholes the energy density, at
the throat, is always negative, while the radial pressure is positive, contrary
to the spherically symmetric Morris-Thorne wormhole. Specific hyperbolic
wormholes are constructed and discussed by imposing different conditions for
the radial and lateral pressures, or by considering restricted choices for the
redshift and the shape functions. In particular, we show that an hyperbolic
wormhole can not be sustained at the throat by phantom energy, and that there
are pseudo-spherically symmetric wormholes supported by matter with isotropic
pressure and characterized by space sections with an angle deficit (or excess).
| [
{
"created": "Mon, 15 Jun 2015 18:01:00 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jun 2015 19:02:57 GMT",
"version": "v2"
}
] | 2015-06-26 | [
[
"Cataldo",
"Mauricio",
""
],
[
"Liempi",
"Luis",
""
],
[
"Rodriguez",
"Pablo",
""
]
] | In this paper we study classical general relativistic static wormhole configurations with pseudo-spherical symmetry. We show that in addition to the hyperbolic wormhole solutions discussed by Lobo and Mimoso in the Ref. Phys.\ Rev.\ D {\bf 82}, 044034 (2010), there exists another wormhole class, which is truly pseudo-spherical counterpart of spherical Morris-Thorne wormhole (contrary to the Lobo-Mimoso wormhole class), since all constraints originally defined by Morris and Thorne for spherically symmetric wormholes are satisfied. We show that, for both classes of hyperbolic wormholes the energy density, at the throat, is always negative, while the radial pressure is positive, contrary to the spherically symmetric Morris-Thorne wormhole. Specific hyperbolic wormholes are constructed and discussed by imposing different conditions for the radial and lateral pressures, or by considering restricted choices for the redshift and the shape functions. In particular, we show that an hyperbolic wormhole can not be sustained at the throat by phantom energy, and that there are pseudo-spherically symmetric wormholes supported by matter with isotropic pressure and characterized by space sections with an angle deficit (or excess). |
gr-qc/0412084 | Marc Lachieze-Rey | Michel Mizony (IGD), Marc Lachieze-Rey (PGC) | Cosmological effects in the local static frame | to appear in Astron. & Astroph | Astron.Astrophys.434:45-52,2005 | 10.1051/0004-6361:20042195 | null | gr-qc astro-ph hep-th | null | What is the influence of cosmology (the expansion law and its acceleration,
the cosmological constant...) on the dynamics and optics of a local system like
the solar system, a galaxy, a cluster, a supercluster...? The answer requires
the solution of Einstein equation with the local source, which tends towards
the cosmological model at large distance. There is, in general, no analytic
expression for the corresponding metric, but we calculate here an expansion in
a small parameter, which allows to answer the question. First, we derive a
static expression for the pure cosmological (Friedmann-Lema\^itre) metric,
whose validity, although local, extends in a very large neighborhood of the
observer. This expression appears as the metric of an osculating de Sitter
model. Then we propose an expansion of the cosmological metric with a local
source, which is valid in a very large neighborhood of the local system. This
allows to calculate exactly the (tiny) influence of cosmology on the dynamics
of the solar system: it results that, contrary to some claims, cosmological
effects fail to account for the unexplained acceleration of the Pioneer probe
by several order of magnitudes. Our expression provide estimations of the
cosmological influence in the calculations of rotation or dispersion velocity
curves in galaxies, clusters, and any type of cosmic structure, necessary for
precise evaluations of dark matter and/or cosmic flows. The same metric can
also be used to estimate the influence of cosmology on gravitational optics in
the vicinity of such systems.
| [
{
"created": "Fri, 17 Dec 2004 13:50:00 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Mizony",
"Michel",
"",
"IGD"
],
[
"Lachieze-Rey",
"Marc",
"",
"PGC"
]
] | What is the influence of cosmology (the expansion law and its acceleration, the cosmological constant...) on the dynamics and optics of a local system like the solar system, a galaxy, a cluster, a supercluster...? The answer requires the solution of Einstein equation with the local source, which tends towards the cosmological model at large distance. There is, in general, no analytic expression for the corresponding metric, but we calculate here an expansion in a small parameter, which allows to answer the question. First, we derive a static expression for the pure cosmological (Friedmann-Lema\^itre) metric, whose validity, although local, extends in a very large neighborhood of the observer. This expression appears as the metric of an osculating de Sitter model. Then we propose an expansion of the cosmological metric with a local source, which is valid in a very large neighborhood of the local system. This allows to calculate exactly the (tiny) influence of cosmology on the dynamics of the solar system: it results that, contrary to some claims, cosmological effects fail to account for the unexplained acceleration of the Pioneer probe by several order of magnitudes. Our expression provide estimations of the cosmological influence in the calculations of rotation or dispersion velocity curves in galaxies, clusters, and any type of cosmic structure, necessary for precise evaluations of dark matter and/or cosmic flows. The same metric can also be used to estimate the influence of cosmology on gravitational optics in the vicinity of such systems. |
0705.2254 | Alexander Zhidenko | Alexander Zhidenko | Quasi-normal modes for black hole solutions unknown in analytical form | 3 pages, 1 figure, RevTeX. Talk to be given at the seminar of Russian
Gravitational Society | null | null | null | gr-qc | null | We review the papers [1-3]. We discuss possibilities of studying the
quasi-normal modes of black holes that are not known in an analytical form.
Such black holes appear as solutions in various theoretical models and real
astrophysical approximations when one takes into account the black hole
neighborhood.
| [
{
"created": "Tue, 15 May 2007 22:51:09 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Zhidenko",
"Alexander",
""
]
] | We review the papers [1-3]. We discuss possibilities of studying the quasi-normal modes of black holes that are not known in an analytical form. Such black holes appear as solutions in various theoretical models and real astrophysical approximations when one takes into account the black hole neighborhood. |
1201.3164 | Chopin Soo | Chopin Soo and Hoi-Lai Yu | General Relativity without paradigm of space-time covariance, and
resolution of the problem of time | 11 pages | Prog Theor Exp Phys (2014) | 10.1142/9789814449373_0006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The framework of a theory of gravity from the quantum to the classical regime
is presented. The paradigm shift from full spacetime covariance to spatial
diffeomorphism invariance, together with clean decomposition of the canonical
structure, yield transparent physical dynamics and a resolution of the problem
of time. The deep divide between quantum mechanics and conventional canonical
formulations of quantum gravity is overcome with a Schr\"{o}dinger equation for
quantum geometrodynamics that describes evolution in intrinsic time. Unitary
time development with gauge-invariant temporal ordering is also viable. All
Kuchar observables become physical; and classical spacetime, with direct
correlation between its proper times and intrinsic time intervals, emerges from
constructive interference. The framework not only yields a physical Hamiltonian
for Einstein's theory, but also prompts natural extensions and improvements
towards a well behaved quantum theory of gravity. It is a consistent canonical
scheme to discuss Horava-Lifshitz theories with intrinsic time evolution, and
of the many possible alternatives that respect 3-covariance (rather than the
more restrictive 4-covariance of Einstein's theory), Horava's ``detailed
balance" form of the Hamiltonian constraint is essentially pinned down by this
framework.
| [
{
"created": "Mon, 16 Jan 2012 07:07:34 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Jul 2012 11:03:29 GMT",
"version": "v2"
},
{
"created": "Sun, 18 Nov 2012 10:28:17 GMT",
"version": "v3"
},
{
"created": "Fri, 5 Jul 2013 13:41:57 GMT",
"version": "v4"
},
{
"created": "Fri, 7 Feb 2014 07:58:31 GMT",
"version": "v5"
}
] | 2019-12-06 | [
[
"Soo",
"Chopin",
""
],
[
"Yu",
"Hoi-Lai",
""
]
] | The framework of a theory of gravity from the quantum to the classical regime is presented. The paradigm shift from full spacetime covariance to spatial diffeomorphism invariance, together with clean decomposition of the canonical structure, yield transparent physical dynamics and a resolution of the problem of time. The deep divide between quantum mechanics and conventional canonical formulations of quantum gravity is overcome with a Schr\"{o}dinger equation for quantum geometrodynamics that describes evolution in intrinsic time. Unitary time development with gauge-invariant temporal ordering is also viable. All Kuchar observables become physical; and classical spacetime, with direct correlation between its proper times and intrinsic time intervals, emerges from constructive interference. The framework not only yields a physical Hamiltonian for Einstein's theory, but also prompts natural extensions and improvements towards a well behaved quantum theory of gravity. It is a consistent canonical scheme to discuss Horava-Lifshitz theories with intrinsic time evolution, and of the many possible alternatives that respect 3-covariance (rather than the more restrictive 4-covariance of Einstein's theory), Horava's ``detailed balance" form of the Hamiltonian constraint is essentially pinned down by this framework. |
gr-qc/0210085 | Mark Goodsell | Mark D. Goodsell, Carl E. Dolby, Stephen F. Gull | A Dirac Sea for a General Non-Inertial Observer In Flat 1+1 Dimensional
Spacetime | 26 pages, 3 figures, submitted to Annals of Physics | null | null | AOP 65052 | gr-qc | null | A coordinate system is set up for a general accelerating observer and is used
to determine the particle content of the Dirac vacuum for that observer.
Equations are obtained for the spatial distribution and total number of
particles for massless fermions as seen by this observer, generalising previous
work.
| [
{
"created": "Thu, 24 Oct 2002 16:54:16 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Goodsell",
"Mark D.",
""
],
[
"Dolby",
"Carl E.",
""
],
[
"Gull",
"Stephen F.",
""
]
] | A coordinate system is set up for a general accelerating observer and is used to determine the particle content of the Dirac vacuum for that observer. Equations are obtained for the spatial distribution and total number of particles for massless fermions as seen by this observer, generalising previous work. |
1003.5652 | Florian Conrady | Florian Conrady (Perimeter Inst. Theor. Phys.) | Spin foams with timelike surfaces | 22 pages, no figures; v2: remarks on operator formalism added in
discussion; correction: the spin 1/2 irrep of the discrete series does not
appear in the Plancherel decomposition | Class. Quant. Grav.27:155014, 2010 | 10.1088/0264-9381/27/15/155014 | PI-QG-179 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spin foams of 4d gravity were recently extended from complexes with purely
spacelike surfaces to complexes that also contain timelike surfaces. In this
article, we express the associated partition function in terms of vertex
amplitudes and integrals over coherent states. The coherent states are
characterized by unit 3--vectors which represent normals to surfaces and lie
either in the 2--sphere or the 2d hyperboloids. In the case of timelike
surfaces, a new type of coherent state is used and the associated completeness
relation is derived. It is also shown that the quantum simplicity constraints
can be deduced by three different methods: by weak imposition of the
constraints, by restriction of coherent state bases and by the master
constraint.
| [
{
"created": "Mon, 29 Mar 2010 19:46:04 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Apr 2010 19:43:06 GMT",
"version": "v2"
}
] | 2011-01-19 | [
[
"Conrady",
"Florian",
"",
"Perimeter Inst. Theor. Phys."
]
] | Spin foams of 4d gravity were recently extended from complexes with purely spacelike surfaces to complexes that also contain timelike surfaces. In this article, we express the associated partition function in terms of vertex amplitudes and integrals over coherent states. The coherent states are characterized by unit 3--vectors which represent normals to surfaces and lie either in the 2--sphere or the 2d hyperboloids. In the case of timelike surfaces, a new type of coherent state is used and the associated completeness relation is derived. It is also shown that the quantum simplicity constraints can be deduced by three different methods: by weak imposition of the constraints, by restriction of coherent state bases and by the master constraint. |
1505.03070 | Elsayed Lashin Dr. | E. I. Lashin | On the correctness of cosmology from quantum potential | 7 pages (just the same as v1 but the height of pages are altered to
make page numbers visible) | Mod. Phys. Lett. A, Vol. 31, No. 7 (2016) 1650044 | 10.1142/S0217732316500449 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine in detail the cosmology based on quantal (Bohmian) trajectories as
suggested in a recent study arXiv:1404.3093[gr-qc]. We disagree with the
conclusions regarding predicting the value of the cosmological constant
$\Lambda$ and evading the big bang singularity. Furthermore, we show that the
approach of using a quantum corrected Raychaudhuri equation (QRE), as suggested
in arXiv:1404.3093[gr-qc], is unsatisfactory, because, essentially, it uses the
Raychaudhuri equation, which is a kinematical equation, in order to predict
dynamics. In addition, even within this inconsistent framework, the authors
have adopted unjustified assumptions and carried out incorrect steps leading to
doubtful conclusions.
| [
{
"created": "Tue, 12 May 2015 15:47:25 GMT",
"version": "v1"
},
{
"created": "Thu, 14 May 2015 12:41:35 GMT",
"version": "v2"
}
] | 2016-03-15 | [
[
"Lashin",
"E. I.",
""
]
] | We examine in detail the cosmology based on quantal (Bohmian) trajectories as suggested in a recent study arXiv:1404.3093[gr-qc]. We disagree with the conclusions regarding predicting the value of the cosmological constant $\Lambda$ and evading the big bang singularity. Furthermore, we show that the approach of using a quantum corrected Raychaudhuri equation (QRE), as suggested in arXiv:1404.3093[gr-qc], is unsatisfactory, because, essentially, it uses the Raychaudhuri equation, which is a kinematical equation, in order to predict dynamics. In addition, even within this inconsistent framework, the authors have adopted unjustified assumptions and carried out incorrect steps leading to doubtful conclusions. |
1211.6632 | Thomas W. Baumgarte | Thomas W. Baumgarte, Pedro J. Montero, Isabel Cordero-Carri\'on, Ewald
M\"uller | Numerical Relativity in Spherical Polar Coordinates: Evolution
Calculations with the BSSN Formulation | 14 pages, 10 figures, submitted to PRD | null | 10.1103/PhysRevD.87.044026 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the absence of symmetry assumptions most numerical relativity simulations
adopt Cartesian coordinates. While Cartesian coordinates have some desirable
properties, spherical polar coordinates appear better suited for certain
applications, including gravitational collapse and supernova simulations.
Development of numerical relativity codes in spherical polar coordinates has
been hampered by the need to handle the coordinate singularities at the origin
and on the axis, for example by careful regularization of the appropriate
variables. Assuming spherical symmetry and adopting a covariant version of the
BSSN equations, Montero and Cordero-Carri\'on recently demonstrated that such a
regularization is not necessary when a partially implicit Runge-Kutta (PIRK)
method is used for the time evolution of the gravitational fields. Here we
report on an implementation of the BSSN equations in spherical polar
coordinates without any symmetry assumptions. Using a PIRK method we obtain
stable simulations in three spatial dimensions without the need to regularize
the origin or the axis. We perform and discuss a number of tests to assess the
stability, accuracy and convergence of the code, namely weak gravitational
waves, "hydro-without-hydro" evolutions of spherical and rotating relativistic
stars in equilibrium, and single black holes.
| [
{
"created": "Wed, 28 Nov 2012 15:23:04 GMT",
"version": "v1"
}
] | 2015-06-12 | [
[
"Baumgarte",
"Thomas W.",
""
],
[
"Montero",
"Pedro J.",
""
],
[
"Cordero-Carrión",
"Isabel",
""
],
[
"Müller",
"Ewald",
""
]
] | In the absence of symmetry assumptions most numerical relativity simulations adopt Cartesian coordinates. While Cartesian coordinates have some desirable properties, spherical polar coordinates appear better suited for certain applications, including gravitational collapse and supernova simulations. Development of numerical relativity codes in spherical polar coordinates has been hampered by the need to handle the coordinate singularities at the origin and on the axis, for example by careful regularization of the appropriate variables. Assuming spherical symmetry and adopting a covariant version of the BSSN equations, Montero and Cordero-Carri\'on recently demonstrated that such a regularization is not necessary when a partially implicit Runge-Kutta (PIRK) method is used for the time evolution of the gravitational fields. Here we report on an implementation of the BSSN equations in spherical polar coordinates without any symmetry assumptions. Using a PIRK method we obtain stable simulations in three spatial dimensions without the need to regularize the origin or the axis. We perform and discuss a number of tests to assess the stability, accuracy and convergence of the code, namely weak gravitational waves, "hydro-without-hydro" evolutions of spherical and rotating relativistic stars in equilibrium, and single black holes. |
1007.2725 | Sumati Surya | Fay Dowker, Steven Johnston, Sumati Surya | On extending the Quantum Measure | 23 pages, 2 figures | J.Phys.A43:505305,2010 | 10.1088/1751-8113/43/50/505305 | null | gr-qc math-ph math.MP quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We point out that a quantum system with a strongly positive quantum measure
or decoherence functional gives rise to a vector valued measure whose domain is
the algebra of events or physical questions. This gives an immediate handle on
the question of the extension of the decoherence functional to the sigma
algebra generated by this algebra of events. It is on the latter that the
physical transition amplitudes directly give the decoherence functional. Since
the full sigma algebra contains physically interesting questions, like the
return question, extending the decoherence functional to these more general
questions is important. We show that the decoherence functional, and hence the
quantum measure, extends if and only if the associated vector measure does. We
give two examples of quantum systems whose decoherence functionals do not
extend: one is a unitary system with finitely many states, and the other is a
quantum sequential growth model for causal sets. These examples fail to extend
in the formal mathematical sense and we speculate on whether the conditions for
extension are unphysically strong.
| [
{
"created": "Fri, 16 Jul 2010 09:44:11 GMT",
"version": "v1"
}
] | 2010-11-30 | [
[
"Dowker",
"Fay",
""
],
[
"Johnston",
"Steven",
""
],
[
"Surya",
"Sumati",
""
]
] | We point out that a quantum system with a strongly positive quantum measure or decoherence functional gives rise to a vector valued measure whose domain is the algebra of events or physical questions. This gives an immediate handle on the question of the extension of the decoherence functional to the sigma algebra generated by this algebra of events. It is on the latter that the physical transition amplitudes directly give the decoherence functional. Since the full sigma algebra contains physically interesting questions, like the return question, extending the decoherence functional to these more general questions is important. We show that the decoherence functional, and hence the quantum measure, extends if and only if the associated vector measure does. We give two examples of quantum systems whose decoherence functionals do not extend: one is a unitary system with finitely many states, and the other is a quantum sequential growth model for causal sets. These examples fail to extend in the formal mathematical sense and we speculate on whether the conditions for extension are unphysically strong. |
1603.07748 | Parthapratim Pradhan | Parthapratim Pradhan | Thermodynamic Products in Extended Phase Space | Accepted in IJMPD | International Journal of Modern Physics D, Vol. 26 (2017) 1750010
(16 pages) | 10.1142/S0218271817500109 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have examined the thermodynamic properties for a variety of spherically
symmetric charged-AdS black hole (BH) solutions, including the charged AdS BH
surrounded by quintessence dark energy and charged AdS BH in $f(R)$ gravity in
\emph{extended phase-space}. This framework involves treating the cosmological
constant as thermodynamic variable (for example: thermodynamic pressure and
thermodynamic volume). Then they should behave as an analog of Van der Waal
(VdW) like systems. In the extended phase space we have calculated the
\emph{entropy product} and \emph{thermodynamic volume product} of all horizons.
The mass (or enthalpy) independent nature of the said product signals they are
\emph{universal} quantities. %Various type of phase diagram of the specific
heat has been drawn. The divergence of the specific heat indicates that the
second order phase transition occurs under certain condition. In the
appendix-A, we have studied the thermodynamic volume products for axisymmetric
spacetime and it is shown to be \emph{not universal} in nature. Finally, in
appendix-B, we have studied the $P-V$ criticality of Cauchy horizon for
charged-AdS BH and found to be an universal relation of critical values between
two horizons as $P_{c}^{-} = P_{c}^{+}$, $v_{c}^{-}=v_{c}^{+}$, $T_{c}^{-} =
-T_{c}^{+}$, $\rho_{c}^{-} = -\rho_{c}^{+}$. The symbols are defined in the
main work.
| [
{
"created": "Thu, 24 Mar 2016 20:45:47 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Jun 2016 06:19:17 GMT",
"version": "v2"
}
] | 2016-08-02 | [
[
"Pradhan",
"Parthapratim",
""
]
] | We have examined the thermodynamic properties for a variety of spherically symmetric charged-AdS black hole (BH) solutions, including the charged AdS BH surrounded by quintessence dark energy and charged AdS BH in $f(R)$ gravity in \emph{extended phase-space}. This framework involves treating the cosmological constant as thermodynamic variable (for example: thermodynamic pressure and thermodynamic volume). Then they should behave as an analog of Van der Waal (VdW) like systems. In the extended phase space we have calculated the \emph{entropy product} and \emph{thermodynamic volume product} of all horizons. The mass (or enthalpy) independent nature of the said product signals they are \emph{universal} quantities. %Various type of phase diagram of the specific heat has been drawn. The divergence of the specific heat indicates that the second order phase transition occurs under certain condition. In the appendix-A, we have studied the thermodynamic volume products for axisymmetric spacetime and it is shown to be \emph{not universal} in nature. Finally, in appendix-B, we have studied the $P-V$ criticality of Cauchy horizon for charged-AdS BH and found to be an universal relation of critical values between two horizons as $P_{c}^{-} = P_{c}^{+}$, $v_{c}^{-}=v_{c}^{+}$, $T_{c}^{-} = -T_{c}^{+}$, $\rho_{c}^{-} = -\rho_{c}^{+}$. The symbols are defined in the main work. |
2201.08415 | Zheng-Wen Long | S. R. Wu, B. Q. Wang, Dong Liu, Z. W. Long | Echoes of charged black-bounce spacetimes | null | null | 10.1140/epjc/s10052-022-10938-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In present work, the evolution of scalar field and electromagnetic field
under the background of the charged black-bounce spacetimes are investigated,
and we obtain an obvious echoes signal which appropriately reports the
properties of the charged black-bounce spacetimes and disclose the physical
reasons behind such phenomena. Furthermore, by studying the quasinormal
ringdown, we analyze the three states of the charged black-bounce spacetimes in
detail, our results show that the echoes signal only appears when $(\rvert
{Q}\rvert \le m)$ and $(\rvert {l}\rvert > m+ \sqrt{m ^{2}-Q^{2} })$ in this
spacetime, while when the parameters demand $(\rvert {Q}\rvert>m)$, the echoes
signal will be transformed into a quasinormal ringdown of the two-way
traversable wormhole, and the charged black-bounce is a regular black hole with
normal horizons by requiring $(\rvert {Q}\rvert \le m)$ and $(\rvert {l}\rvert
< m- \sqrt{m ^{2}-Q^{2} })$.
| [
{
"created": "Wed, 19 Jan 2022 00:59:41 GMT",
"version": "v1"
},
{
"created": "Sun, 30 Jan 2022 16:30:32 GMT",
"version": "v2"
},
{
"created": "Tue, 5 Jul 2022 21:23:18 GMT",
"version": "v3"
}
] | 2022-11-23 | [
[
"Wu",
"S. R.",
""
],
[
"Wang",
"B. Q.",
""
],
[
"Liu",
"Dong",
""
],
[
"Long",
"Z. W.",
""
]
] | In present work, the evolution of scalar field and electromagnetic field under the background of the charged black-bounce spacetimes are investigated, and we obtain an obvious echoes signal which appropriately reports the properties of the charged black-bounce spacetimes and disclose the physical reasons behind such phenomena. Furthermore, by studying the quasinormal ringdown, we analyze the three states of the charged black-bounce spacetimes in detail, our results show that the echoes signal only appears when $(\rvert {Q}\rvert \le m)$ and $(\rvert {l}\rvert > m+ \sqrt{m ^{2}-Q^{2} })$ in this spacetime, while when the parameters demand $(\rvert {Q}\rvert>m)$, the echoes signal will be transformed into a quasinormal ringdown of the two-way traversable wormhole, and the charged black-bounce is a regular black hole with normal horizons by requiring $(\rvert {Q}\rvert \le m)$ and $(\rvert {l}\rvert < m- \sqrt{m ^{2}-Q^{2} })$. |
gr-qc/0003042 | Masafumi Seriu | Masafumi Seriu | Spectral Evolution of the Universe | To appear in Phys. Rev. D | Phys.Rev. D62 (2000) 023516 | 10.1103/PhysRevD.62.023516 | null | gr-qc | null | We derive the evolution equations for the spectra of the Universe.
Here "spectra" means the eigenvalues of the Laplacian defined on a space,
which contain the geometrical information on the space.
These equations are expected to be useful to analyze the evolution of the
geometrical structures of the Universe.
As an application, we investigate the time evolution of the spectral distance
between two Universes that are very close to each other; it is the first
necessary step for the detailed analysis of the model-fitting problem in
cosmology with the spectral scheme.
We find out a universal formula for the spectral distance between two very
close Universes, which turns out to be independent of the detailed form of the
distance nor the gravity theory. Then we investigate its time evolution with
the help of the evolution equations we derive.
We also formulate the criteria for a good cosmological model in terms of the
spectral distance.
| [
{
"created": "Fri, 10 Mar 2000 01:37:10 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Mar 2000 17:53:14 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Seriu",
"Masafumi",
""
]
] | We derive the evolution equations for the spectra of the Universe. Here "spectra" means the eigenvalues of the Laplacian defined on a space, which contain the geometrical information on the space. These equations are expected to be useful to analyze the evolution of the geometrical structures of the Universe. As an application, we investigate the time evolution of the spectral distance between two Universes that are very close to each other; it is the first necessary step for the detailed analysis of the model-fitting problem in cosmology with the spectral scheme. We find out a universal formula for the spectral distance between two very close Universes, which turns out to be independent of the detailed form of the distance nor the gravity theory. Then we investigate its time evolution with the help of the evolution equations we derive. We also formulate the criteria for a good cosmological model in terms of the spectral distance. |
1712.04362 | Wei Zhang | Wei Zhang and Xiao-Mei Kuang | The quantum effect on Friedmann equation in FRW universe | 10 pages | AHEP 6758078(2018) | 10.1155/2018/6758078 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the modified Friedmann equation in the Friedmann-Robertson-Walker
universe with quantum effect. Our modified results mainly stem from the new
entropy-area relation and the novel idea of T. Padmanabhan, who considers the
cosmic space to be emerged from the cosmic time progresses, so that the
expansion rate of the universe is determined by the difference of degrees of
freedom between the holographic surface and the bulk inside. We also discuss
the possibility of having bounce cosmological solution from the modified
Friedmann equation in spatially flat geometry.
| [
{
"created": "Tue, 12 Dec 2017 15:54:38 GMT",
"version": "v1"
}
] | 2018-03-15 | [
[
"Zhang",
"Wei",
""
],
[
"Kuang",
"Xiao-Mei",
""
]
] | We study the modified Friedmann equation in the Friedmann-Robertson-Walker universe with quantum effect. Our modified results mainly stem from the new entropy-area relation and the novel idea of T. Padmanabhan, who considers the cosmic space to be emerged from the cosmic time progresses, so that the expansion rate of the universe is determined by the difference of degrees of freedom between the holographic surface and the bulk inside. We also discuss the possibility of having bounce cosmological solution from the modified Friedmann equation in spatially flat geometry. |
0910.4559 | J. -F. Pascual-Sanchez | A. San Miguel, F. Vicente and J.-F. Pascual-Sanchez | Numerical estimation of the curvature of a light wavefront in a weak
gravitational field | 22 pages, 6 figs, accepted in Classical and Quantum Gravity | Class.Quant.Grav.26:235004,2009 | 10.1088/0264-9381/26/23/235004 | null | gr-qc astro-ph.IM astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The geometry of a light wavefront evolving in the 3--space associated with a
post-Newtonian relativistic spacetime from a flat wavefront is studied
numerically by means of the ray tracing method. For a discretization of the
bidimensional wavefront the surface fitting technique is used to determine the
curvature of this surface at each vertex of the mesh. The relationship between
the curvature of a wavefront and the change of the arrival time at different
points on the Earth is also numerically discussed.
| [
{
"created": "Fri, 23 Oct 2009 18:08:32 GMT",
"version": "v1"
}
] | 2010-02-26 | [
[
"Miguel",
"A. San",
""
],
[
"Vicente",
"F.",
""
],
[
"Pascual-Sanchez",
"J. -F.",
""
]
] | The geometry of a light wavefront evolving in the 3--space associated with a post-Newtonian relativistic spacetime from a flat wavefront is studied numerically by means of the ray tracing method. For a discretization of the bidimensional wavefront the surface fitting technique is used to determine the curvature of this surface at each vertex of the mesh. The relationship between the curvature of a wavefront and the change of the arrival time at different points on the Earth is also numerically discussed. |
1402.0690 | Julien Cortier | Julien Cortier and Vincent Minerbe | On complete stationary vacuum initial data | 11 pages | null | null | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe a proof of M.T. Anderson's result on the rigidity of complete
stationary initial data for the Einstein vacuum equations in spacetime
dimension 3 + 1, under an extra assumption on the norm of the stationary
Killing vector field. The argument only involves basic comparison geometry
along with some Bochner-Weitzenb\"ock formula techniques. We also discuss on
the possibility to extend those techniques in higher dimensions.
| [
{
"created": "Tue, 4 Feb 2014 11:03:59 GMT",
"version": "v1"
}
] | 2014-02-05 | [
[
"Cortier",
"Julien",
""
],
[
"Minerbe",
"Vincent",
""
]
] | We describe a proof of M.T. Anderson's result on the rigidity of complete stationary initial data for the Einstein vacuum equations in spacetime dimension 3 + 1, under an extra assumption on the norm of the stationary Killing vector field. The argument only involves basic comparison geometry along with some Bochner-Weitzenb\"ock formula techniques. We also discuss on the possibility to extend those techniques in higher dimensions. |
2205.13548 | Marco Astorino | Marco Astorino, Riccardo Martelli, Adriano Vigan\`o | Black holes in a swirling universe | v4: 22 pages, 11 figures, updated pictures about geodesic motion | Phys. Rev. D 106, 064014 (2022) | 10.1103/PhysRevD.106.064014 | IFUM-1093-FT | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We present a new solution in Einstein's General Relativity representing a
Schwarzschild black hole immersed in a rotating universe. Such a solution is
constructed analytically by means of the last unexplored Lie point symmetry of
the Ernst equations for stationary and axisymmetric spacetimes. This kind of
the Ehlers transformation is able to embed any given solution into a rotating
background, which is not of NUT type. We analyse the physical properties,
ergoregions and geodesics of the new metric, which is regular outside the event
horizon and has a well defined thermodynamics. We finally consider the Kerr
generalisation.
| [
{
"created": "Thu, 26 May 2022 18:00:00 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Sep 2022 21:39:50 GMT",
"version": "v2"
},
{
"created": "Sat, 26 Nov 2022 17:18:57 GMT",
"version": "v3"
},
{
"created": "Wed, 7 Feb 2024 18:00:37 GMT",
"version": "v4"
}
] | 2024-02-08 | [
[
"Astorino",
"Marco",
""
],
[
"Martelli",
"Riccardo",
""
],
[
"Viganò",
"Adriano",
""
]
] | We present a new solution in Einstein's General Relativity representing a Schwarzschild black hole immersed in a rotating universe. Such a solution is constructed analytically by means of the last unexplored Lie point symmetry of the Ernst equations for stationary and axisymmetric spacetimes. This kind of the Ehlers transformation is able to embed any given solution into a rotating background, which is not of NUT type. We analyse the physical properties, ergoregions and geodesics of the new metric, which is regular outside the event horizon and has a well defined thermodynamics. We finally consider the Kerr generalisation. |
1010.5200 | Laura Cadonati | Sebastian Fischetti, James Healy, Laura Cadonati, Lionel London,
Satyanarayan R.P. Mohapatra, Deirdre Shoemaker | Exploring the Use of Numerical Relativity Waveforms in Burst Analysis of
Precessing Black Hole Mergers | 9 pages, 15 figures | Phys.Rev.D83:044019,2011 | 10.1103/PhysRevD.83.044019 | LIGO Document Control Center P1000092 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent years have witnessed tremendous progress in numerical relativity and
an ever improving performance of ground-based interferometric gravitational
wave detectors. In preparation for Advanced LIGO and a new era in gravitational
wave astronomy, the numerical relativity and gravitational wave data analysis
communities are collaborating to ascertain the most useful role for numerical
relativity waveforms in the detection and characterization of binary black hole
coalescences. In this paper, we explore the detectability of equal mass,
merging black hole binaries with precessing spins and total mass M_T in
[80,350]Msol, using numerical relativity waveforms and template-less search
algorithms designed for gravitational wave bursts. In particular, we present a
systematic study using waveforms produced by the MAYAKRANC code that are added
to colored, Gaussian noise and analyzed with the Omega burst search algorithm.
Detection efficiency is weighed against the orientation of one of the
black-hole's spin axes. We find a strong correlation between the detection
efficiency and the radiated energy and angular momentum, and that the inclusion
of the l=2, m=+/-1,0 modes, at a minimum, is necessary to account for the full
dynamics of precessing systems.
| [
{
"created": "Mon, 25 Oct 2010 17:29:01 GMT",
"version": "v1"
}
] | 2011-02-18 | [
[
"Fischetti",
"Sebastian",
""
],
[
"Healy",
"James",
""
],
[
"Cadonati",
"Laura",
""
],
[
"London",
"Lionel",
""
],
[
"Mohapatra",
"Satyanarayan R. P.",
""
],
[
"Shoemaker",
"Deirdre",
""
]
] | Recent years have witnessed tremendous progress in numerical relativity and an ever improving performance of ground-based interferometric gravitational wave detectors. In preparation for Advanced LIGO and a new era in gravitational wave astronomy, the numerical relativity and gravitational wave data analysis communities are collaborating to ascertain the most useful role for numerical relativity waveforms in the detection and characterization of binary black hole coalescences. In this paper, we explore the detectability of equal mass, merging black hole binaries with precessing spins and total mass M_T in [80,350]Msol, using numerical relativity waveforms and template-less search algorithms designed for gravitational wave bursts. In particular, we present a systematic study using waveforms produced by the MAYAKRANC code that are added to colored, Gaussian noise and analyzed with the Omega burst search algorithm. Detection efficiency is weighed against the orientation of one of the black-hole's spin axes. We find a strong correlation between the detection efficiency and the radiated energy and angular momentum, and that the inclusion of the l=2, m=+/-1,0 modes, at a minimum, is necessary to account for the full dynamics of precessing systems. |
2405.08241 | Ruibo Wang | Rui-Bo Wang, Shi-Jie Ma, Lei You, Yu-Cheng Tang, Yu-Hang Feng, Xian-Ru
Hu and Jian-Bo Deng | Thermodynamics of AdS-Schwarzschild-like black hole in loop quantum
gravity | 35 pages, 8 figures, 1 table | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtained the metric of Schwarzschild-like black hole with LQG correction
in anti-de Sitter (AdS) space-time under the assumption that cosmological
constant is decoupled in loop quantum gravity (LQG), and investigated its
thermodynamics, including equation of state, criticality, heat capacity and
Gibbs free energy. $P$-$v$ graph is plotted and critical behavior has been
calculated. It is found that due to LQG effect, quantum corrected
Schwarzschild-AdS black hole has critical point and a critical ratio $7/18$. It
is different from RN-AdS black hole $3/8$ (the same as Van der Waals system).
But there are still some similarities compared to Van der Waals system, like
same critical exponents and a similar $P$-$v$ graph. Moreover, it is concluded
that energy-momentum tensor related to black hole's mass could break the usual
first law. The modified first law will violate the conservation of Gibbs free
energy during the first order phase transition. Joule-Thomson expansion is also
studied. It is interesting that compared with Schwarzschild-AdS black hole, LQG
effect leads to inversion points. The inversion curve divides $T$-$P$
coordinate system into two zones: heating region and cooling region, which is
shown in inversion curves and isenthalpic curves detailedly. The results showed
that there is a minimum inversion mass, which makes any black holes with a mass
smaller than this value won't have inversion point.
| [
{
"created": "Mon, 13 May 2024 23:51:07 GMT",
"version": "v1"
},
{
"created": "Sat, 15 Jun 2024 04:40:45 GMT",
"version": "v2"
}
] | 2024-06-18 | [
[
"Wang",
"Rui-Bo",
""
],
[
"Ma",
"Shi-Jie",
""
],
[
"You",
"Lei",
""
],
[
"Tang",
"Yu-Cheng",
""
],
[
"Feng",
"Yu-Hang",
""
],
[
"Hu",
"Xian-Ru",
""
],
[
"Deng",
"Jian-Bo",
""
]
] | We obtained the metric of Schwarzschild-like black hole with LQG correction in anti-de Sitter (AdS) space-time under the assumption that cosmological constant is decoupled in loop quantum gravity (LQG), and investigated its thermodynamics, including equation of state, criticality, heat capacity and Gibbs free energy. $P$-$v$ graph is plotted and critical behavior has been calculated. It is found that due to LQG effect, quantum corrected Schwarzschild-AdS black hole has critical point and a critical ratio $7/18$. It is different from RN-AdS black hole $3/8$ (the same as Van der Waals system). But there are still some similarities compared to Van der Waals system, like same critical exponents and a similar $P$-$v$ graph. Moreover, it is concluded that energy-momentum tensor related to black hole's mass could break the usual first law. The modified first law will violate the conservation of Gibbs free energy during the first order phase transition. Joule-Thomson expansion is also studied. It is interesting that compared with Schwarzschild-AdS black hole, LQG effect leads to inversion points. The inversion curve divides $T$-$P$ coordinate system into two zones: heating region and cooling region, which is shown in inversion curves and isenthalpic curves detailedly. The results showed that there is a minimum inversion mass, which makes any black holes with a mass smaller than this value won't have inversion point. |
1908.04266 | Hossein Mohseni Sadjadi | H. Mohseni Sadjadi, V. Anari | End of the constant-roll inflation, and the reheating temperature | 23 pages, 14 figures, accepted for publication in "Physics of the
Dark Universe" | Physics of the Dark Universe 27 (2020) 100474 | 10.1016/j.dark.2020.100474 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | By extending the potential, we propose a mechanism for the end of the
constant-roll inflation and the subsequent reheating phase in the FLRW
space-time. Based on astrophysical data, we estimate the Universe reheating
temperature.
| [
{
"created": "Tue, 6 Aug 2019 11:27:10 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Dec 2019 06:48:39 GMT",
"version": "v2"
},
{
"created": "Tue, 14 Jan 2020 14:02:16 GMT",
"version": "v3"
}
] | 2020-01-22 | [
[
"Sadjadi",
"H. Mohseni",
""
],
[
"Anari",
"V.",
""
]
] | By extending the potential, we propose a mechanism for the end of the constant-roll inflation and the subsequent reheating phase in the FLRW space-time. Based on astrophysical data, we estimate the Universe reheating temperature. |
0912.3992 | Sandro Micheletti | Sandro M. R. Micheletti | Observational constraints on holographic tachyonic dark energy in
interaction with dark matter | 14 pages, 5 figures | JCAP 1005:009,2010 | 10.1088/1475-7516/2010/05/009 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss an interacting tachyonic dark energy model in the context of the
holographic principle. The potential of the holographic tachyon field in
interaction with dark matter is constructed. The model results are compared
with CMB shift parameter, baryonic acoustic oscilations, lookback time and the
Constitution supernovae sample. The coupling constant of the model is
compatible with zero, but dark energy is not given by a cosmological constant.
| [
{
"created": "Sun, 20 Dec 2009 08:30:48 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Dec 2009 07:05:41 GMT",
"version": "v2"
},
{
"created": "Thu, 13 May 2010 03:36:51 GMT",
"version": "v3"
}
] | 2010-05-25 | [
[
"Micheletti",
"Sandro M. R.",
""
]
] | We discuss an interacting tachyonic dark energy model in the context of the holographic principle. The potential of the holographic tachyon field in interaction with dark matter is constructed. The model results are compared with CMB shift parameter, baryonic acoustic oscilations, lookback time and the Constitution supernovae sample. The coupling constant of the model is compatible with zero, but dark energy is not given by a cosmological constant. |
2311.11764 | Ding-Fang Zeng | Ding-fang Zeng | Microscopic State of BHs and an Exact One Body Method for Binary
Dynamics in General Relativity | 32 pages, 22 figures, comparison with observational data added,
expression and grammar revision | Eur. Phys. J. C 84, 370 (2024) | 10.1140/epjc/s10052-024-12683-z | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In gravitational collapses, the horizon and singularity's realisation in the
finite future of the proper time used co-moving observer happens in the future
of infinitely far away future of the normal time used outside probe. To the
latter the horizon and singularity of a black hole formed through gravitational
collapse are physical realities only in the sense of uncertainty principle and
ensemble interpretation. We provide two exact time dependent solution families
to the Einstein equation and show that they form a pair of complementarity
description for the microscopic state of black holes by showing that the
Bekenstein-Hawking entropy formula follows properly from their canonical wave
function's degeneracy. We also develop an eXact One Body method for general
relativity two-body dynamics whose conservative part requires no perturbative
input from post newtonian approximation and applies to the full three stages of
black hole binary merger events. By this method, we analytically calculate the
gravitational wave forms following from such merger processes. In the case
black holes carry exact and apriori horizon and singularity our wave forms
agree with those following from conventional effective one body method but
exhibit more consistent late time behaviour. In the case the black holes carry
only asymptotic horizon and extended inner structure thus experiencing banana
shape deformation as the merger progresses, our wave forms exhibit all features
especially the late time quasi-normal mode type oscillation seen in real
observations.
| [
{
"created": "Mon, 20 Nov 2023 13:46:49 GMT",
"version": "v1"
},
{
"created": "Mon, 11 Dec 2023 13:06:46 GMT",
"version": "v2"
}
] | 2024-04-10 | [
[
"Zeng",
"Ding-fang",
""
]
] | In gravitational collapses, the horizon and singularity's realisation in the finite future of the proper time used co-moving observer happens in the future of infinitely far away future of the normal time used outside probe. To the latter the horizon and singularity of a black hole formed through gravitational collapse are physical realities only in the sense of uncertainty principle and ensemble interpretation. We provide two exact time dependent solution families to the Einstein equation and show that they form a pair of complementarity description for the microscopic state of black holes by showing that the Bekenstein-Hawking entropy formula follows properly from their canonical wave function's degeneracy. We also develop an eXact One Body method for general relativity two-body dynamics whose conservative part requires no perturbative input from post newtonian approximation and applies to the full three stages of black hole binary merger events. By this method, we analytically calculate the gravitational wave forms following from such merger processes. In the case black holes carry exact and apriori horizon and singularity our wave forms agree with those following from conventional effective one body method but exhibit more consistent late time behaviour. In the case the black holes carry only asymptotic horizon and extended inner structure thus experiencing banana shape deformation as the merger progresses, our wave forms exhibit all features especially the late time quasi-normal mode type oscillation seen in real observations. |
2210.13185 | Ying Wang | Xin Wu, Ying Wang, Wei Sun, Fu-Yao Liu, Wen-Biao Han | Explicit symplectic methods in black hole spacetimes | 16pages,accepted by Astrophysical Journal | null | 10.3847/1538-4357/ac9c5d | null | gr-qc nlin.CD physics.comp-ph | http://creativecommons.org/licenses/by/4.0/ | Many Hamiltonian problems in the Solar System are separable or separate into
two analytically solvable parts, and thus give a great chance to the
development and application of explicit symplectic integrators based on
operator splitting and composing. However, such constructions cannot in general
be available for curved spacetimes in general relativity and modified theories
of gravity, because these curved spacetimes correspond to nonseparable
Hamiltonians without the two part splits. Recently, several black hole
spacetimes such as the Schwarzschild black hole were found to allow the
construction of explicit symplectic integrators, since their corresponding
Hamiltonians are separable into more than two explicitly integrable pieces.
Although some other curved spacetimes including the Kerr black hole do not
exist such multi part splits, their corresponding appropriate time
transformation Hamiltonians do. In fact, the key problem for the obtainment of
symplectic analytically integrable decomposition algorithms is how to split
these Hamiltonians or time transformation Hamiltonians. Considering this idea,
we develop explicit sympelcetic schemes in curved spacetimes. We introduce a
class of spacetimes whose Hamiltonians are directly split into several
explicitly integrable terms. For example, the Hamiltonian of rotating black
ring has a 13 part split. We also present two sets of spacetimes whose
appropriate time transformation Hamiltonians have the desirable splits. For
instance, an 8 part split exists in a time-transformed Hamiltonian of
Kerr-Newman solution with disformal parameter. In this way, the proposed
symplectic splitting methods will be used widely for long-term integrations of
orbits in most curved spacetimes we have known.
| [
{
"created": "Fri, 21 Oct 2022 02:26:45 GMT",
"version": "v1"
}
] | 2022-12-07 | [
[
"Wu",
"Xin",
""
],
[
"Wang",
"Ying",
""
],
[
"Sun",
"Wei",
""
],
[
"Liu",
"Fu-Yao",
""
],
[
"Han",
"Wen-Biao",
""
]
] | Many Hamiltonian problems in the Solar System are separable or separate into two analytically solvable parts, and thus give a great chance to the development and application of explicit symplectic integrators based on operator splitting and composing. However, such constructions cannot in general be available for curved spacetimes in general relativity and modified theories of gravity, because these curved spacetimes correspond to nonseparable Hamiltonians without the two part splits. Recently, several black hole spacetimes such as the Schwarzschild black hole were found to allow the construction of explicit symplectic integrators, since their corresponding Hamiltonians are separable into more than two explicitly integrable pieces. Although some other curved spacetimes including the Kerr black hole do not exist such multi part splits, their corresponding appropriate time transformation Hamiltonians do. In fact, the key problem for the obtainment of symplectic analytically integrable decomposition algorithms is how to split these Hamiltonians or time transformation Hamiltonians. Considering this idea, we develop explicit sympelcetic schemes in curved spacetimes. We introduce a class of spacetimes whose Hamiltonians are directly split into several explicitly integrable terms. For example, the Hamiltonian of rotating black ring has a 13 part split. We also present two sets of spacetimes whose appropriate time transformation Hamiltonians have the desirable splits. For instance, an 8 part split exists in a time-transformed Hamiltonian of Kerr-Newman solution with disformal parameter. In this way, the proposed symplectic splitting methods will be used widely for long-term integrations of orbits in most curved spacetimes we have known. |
0912.5311 | Bernard Kelly | Bernard J. Kelly, Wolfgang Tichy, Yosef Zlochower, Manuela Campanelli,
Bernard Whiting | Post-Newtonian Initial Data with Waves: Progress in Evolution | 13 pages, 9 figures. Invited paper from Numerical Relativity and Data
Analysis (NRDA) 2009, Albert Einstein Institute, Potsdam. Corrected to match
published version. | Class.Quant.Grav.27:114005,2010 | 10.1088/0264-9381/27/11/114005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In Kelly et al. [Phys. Rev. D, 76:024008, 2007], we presented new binary
black-hole initial data adapted to puncture evolutions in numerical relativity.
This data satisfies the constraint equations to 2.5 post-Newtonian order, and
contains a transverse-traceless "wavy" metric contribution, violating the
standard assumption of conformal flatness. We report on progress in evolving
this data with a modern moving-puncture implementation of the BSSN equations in
several numerical codes. We discuss the effect of the new metric terms on junk
radiation and continuity of physical radiation extracted.
| [
{
"created": "Tue, 29 Dec 2009 14:29:48 GMT",
"version": "v1"
},
{
"created": "Tue, 11 May 2010 15:50:47 GMT",
"version": "v2"
}
] | 2010-05-25 | [
[
"Kelly",
"Bernard J.",
""
],
[
"Tichy",
"Wolfgang",
""
],
[
"Zlochower",
"Yosef",
""
],
[
"Campanelli",
"Manuela",
""
],
[
"Whiting",
"Bernard",
""
]
] | In Kelly et al. [Phys. Rev. D, 76:024008, 2007], we presented new binary black-hole initial data adapted to puncture evolutions in numerical relativity. This data satisfies the constraint equations to 2.5 post-Newtonian order, and contains a transverse-traceless "wavy" metric contribution, violating the standard assumption of conformal flatness. We report on progress in evolving this data with a modern moving-puncture implementation of the BSSN equations in several numerical codes. We discuss the effect of the new metric terms on junk radiation and continuity of physical radiation extracted. |
1201.4790 | Jiri Podolsky | Jiri Podolsky, Robert Svarc | Interpreting spacetimes of any dimension using geodesic deviation | 19 pages, 2 figures. To appear in Phys. Rev. D. The reference [125]
added | Phys.Rev.D85:044057,2012 | 10.1103/PhysRevD.85.044057 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a general method which can be used for geometrical and physical
interpretation of an arbitrary spacetime in four or any higher number of
dimensions. It is based on the systematic analysis of relative motion of free
test particles. We demonstrate that local effect of the gravitational field on
particles, as described by equation of geodesic deviation with respect to a
natural orthonormal frame, can always be decomposed into a canonical set of
transverse, longitudinal and Newton-Coulomb-type components, isotropic
influence of a cosmological constant, and contributions arising from specific
matter content of the universe. In particular, exact gravitational waves in
Einstein's theory always exhibit themselves via purely transverse effects with
D(D-3)/2 independent polarization states. To illustrate the utility of this
approach we study the family of pp-wave spacetimes in higher dimensions and
discuss specific measurable effects on a detector located in four spacetime
dimensions. For example, the corresponding deformations caused by a generic
higher-dimensional gravitational waves observed in such physical subspace, need
not be tracefree.
| [
{
"created": "Mon, 23 Jan 2012 18:10:24 GMT",
"version": "v1"
},
{
"created": "Fri, 27 Jan 2012 17:00:01 GMT",
"version": "v2"
}
] | 2015-06-03 | [
[
"Podolsky",
"Jiri",
""
],
[
"Svarc",
"Robert",
""
]
] | We present a general method which can be used for geometrical and physical interpretation of an arbitrary spacetime in four or any higher number of dimensions. It is based on the systematic analysis of relative motion of free test particles. We demonstrate that local effect of the gravitational field on particles, as described by equation of geodesic deviation with respect to a natural orthonormal frame, can always be decomposed into a canonical set of transverse, longitudinal and Newton-Coulomb-type components, isotropic influence of a cosmological constant, and contributions arising from specific matter content of the universe. In particular, exact gravitational waves in Einstein's theory always exhibit themselves via purely transverse effects with D(D-3)/2 independent polarization states. To illustrate the utility of this approach we study the family of pp-wave spacetimes in higher dimensions and discuss specific measurable effects on a detector located in four spacetime dimensions. For example, the corresponding deformations caused by a generic higher-dimensional gravitational waves observed in such physical subspace, need not be tracefree. |
1404.4792 | Stefano Vitale | Stefano Vitale, Giuseppe Congedo, Rita Dolesi, Valerio Ferroni, Mauro
Hueller, Daniele Vetrugno, William Joseph Weber, Heather Audley, Karsten
Danzmann, Ingo Diepholz, Martin Hewitson, Natalia Korsakova, Luigi Ferraioli,
Ferran Gibert, Nikolaos Karnesis, Miquel Nofrarias, Henri Inchauspe, Eric
Plagnol, Oliver Jennrich and Paul W. McNamara, Michele Armano, James Ira
Thorpe, Peter Wass | Data series subtraction with unknown and unmodeled background noise | To appear Phys. Rev. D90 August 2014 | Physical Review D 90, 042003 (2014) | 10.1103/PhysRevD.90.042003 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | LISA Pathfinder (LPF), ESA's precursor mission to a gravitational wave
observatory, will measure the degree to which two test-masses can be put into
free-fall, aiming to demonstrate a residual relative acceleration with a power
spectral density (PSD) below 30 fm/s$^2$/Hz$^{1/2}$ around 1 mHz. In LPF data
analysis, the measured relative acceleration data series must be fit to other
various measured time series data. This fitting is required in different
experiments, from system identification of the test mass and satellite dynamics
to the subtraction of noise contributions from measured known disturbances. In
all cases, the background noise, described by the PSD of the fit residuals, is
expected to be coloured, requiring that we perform such fits in the frequency
domain. This PSD is unknown {\it a priori}, and a high accuracy estimate of
this residual acceleration noise is an essential output of our analysis. In
this paper we present a fitting method based on Bayesian parameter estimation
with an unknown frequency-dependent background noise. The method uses noise
marginalisation in connection with averaged Welch's periodograms to achieve
unbiased parameter estimation, together with a consistent, non-parametric
estimate of the residual PSD. Additionally, we find that the method is
equivalent to some implementations of iteratively re-weighted least-squares
fitting. We have tested the method both on simulated data of known PSD, and to
analyze differential acceleration from several experiments with the LISA
Pathfinder end-to-end mission simulator.
| [
{
"created": "Fri, 18 Apr 2014 14:18:26 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Aug 2014 14:42:30 GMT",
"version": "v2"
}
] | 2014-08-15 | [
[
"Vitale",
"Stefano",
""
],
[
"Congedo",
"Giuseppe",
""
],
[
"Dolesi",
"Rita",
""
],
[
"Ferroni",
"Valerio",
""
],
[
"Hueller",
"Mauro",
""
],
[
"Vetrugno",
"Daniele",
""
],
[
"Weber",
"William Joseph",
""
],
[
"Audley",
"Heather",
""
],
[
"Danzmann",
"Karsten",
""
],
[
"Diepholz",
"Ingo",
""
],
[
"Hewitson",
"Martin",
""
],
[
"Korsakova",
"Natalia",
""
],
[
"Ferraioli",
"Luigi",
""
],
[
"Gibert",
"Ferran",
""
],
[
"Karnesis",
"Nikolaos",
""
],
[
"Nofrarias",
"Miquel",
""
],
[
"Inchauspe",
"Henri",
""
],
[
"Plagnol",
"Eric",
""
],
[
"Jennrich",
"Oliver",
""
],
[
"McNamara",
"Paul W.",
""
],
[
"Armano",
"Michele",
""
],
[
"Thorpe",
"James Ira",
""
],
[
"Wass",
"Peter",
""
]
] | LISA Pathfinder (LPF), ESA's precursor mission to a gravitational wave observatory, will measure the degree to which two test-masses can be put into free-fall, aiming to demonstrate a residual relative acceleration with a power spectral density (PSD) below 30 fm/s$^2$/Hz$^{1/2}$ around 1 mHz. In LPF data analysis, the measured relative acceleration data series must be fit to other various measured time series data. This fitting is required in different experiments, from system identification of the test mass and satellite dynamics to the subtraction of noise contributions from measured known disturbances. In all cases, the background noise, described by the PSD of the fit residuals, is expected to be coloured, requiring that we perform such fits in the frequency domain. This PSD is unknown {\it a priori}, and a high accuracy estimate of this residual acceleration noise is an essential output of our analysis. In this paper we present a fitting method based on Bayesian parameter estimation with an unknown frequency-dependent background noise. The method uses noise marginalisation in connection with averaged Welch's periodograms to achieve unbiased parameter estimation, together with a consistent, non-parametric estimate of the residual PSD. Additionally, we find that the method is equivalent to some implementations of iteratively re-weighted least-squares fitting. We have tested the method both on simulated data of known PSD, and to analyze differential acceleration from several experiments with the LISA Pathfinder end-to-end mission simulator. |
1012.3713 | Mercedes Martin-Benito | M Mart\'in-Benito, L J Garay, G A Mena Marug\'an | Quantum Gowdy model within the new loop quantum cosmology improved
dynamics | 4 pages, jpconf.cls, to appear in Proceedings of Spanish Relativity
Meeting 2010 (ERE 2010) held in Granada, Spain | null | 10.1088/1742-6596/314/1/012047 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The linearly polarized Gowdy $T^3$ model can be regarded as compact Bianchi I
cosmologies with inhomogeneous modes allowed to travel in one direction. We
study a hybrid quantization of this model that combines the loop quantization
of the Bianchi I background, adopting the improved dynamics scheme put forward
by Ashtekar and Wilson-Ewing, with a Fock quantization for the inhomogeneities.
The Hamiltonian constraint operator provides a resolution of the cosmological
singularity and superselects separable sectors. We analyze the complicated
structure of these sectors. In any of them the Hamiltonian constraint provides
an evolution equation with respect to the volume of the associated Bianchi I
universe, with a well posed initial value problem. This fact allows us to
construct the Hilbert space of physical states and to show that we recover the
standard quantum field theory for the inhomogeneities.
| [
{
"created": "Thu, 16 Dec 2010 18:40:07 GMT",
"version": "v1"
}
] | 2015-05-20 | [
[
"Martín-Benito",
"M",
""
],
[
"Garay",
"L J",
""
],
[
"Marugán",
"G A Mena",
""
]
] | The linearly polarized Gowdy $T^3$ model can be regarded as compact Bianchi I cosmologies with inhomogeneous modes allowed to travel in one direction. We study a hybrid quantization of this model that combines the loop quantization of the Bianchi I background, adopting the improved dynamics scheme put forward by Ashtekar and Wilson-Ewing, with a Fock quantization for the inhomogeneities. The Hamiltonian constraint operator provides a resolution of the cosmological singularity and superselects separable sectors. We analyze the complicated structure of these sectors. In any of them the Hamiltonian constraint provides an evolution equation with respect to the volume of the associated Bianchi I universe, with a well posed initial value problem. This fact allows us to construct the Hilbert space of physical states and to show that we recover the standard quantum field theory for the inhomogeneities. |
1708.02907 | R. E. Kastner | R. E. Kastner and S. Kauffman | Are Dark Energy and Dark Matter Different Aspects of the Same Physical
Process? | Some typos corrected. Comments welcome, pro or con | null | null | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is suggested that the apparently disparate cosmological phenomena
attributed to so-called 'dark matter' and 'dark energy' arise from the same
fundamental physical process: the emergence, from the quantum level, of
spacetime itself. This creation of spacetime results in metric expansion around
mass points in addition to the usual curvature due to stress-energy sources of
the gravitational field. A recent modification of Einstein's theory of general
relativity by Chadwick, Hodgkinson, and McDonald incorporating spacetime
expansion around mass points, which accounts well for the observed galactic
rotation curves, is adduced in support of the proposal. Recent observational
evidence corroborates a prediction of the model that the apparent amount of
'dark matter' increases with the age of the universe. In addition, the proposal
leads to the same result for the small but nonvanishing cosmological constant,
related to 'dark energy, as that of the causet model of Sorkin et al.
| [
{
"created": "Wed, 9 Aug 2017 16:59:20 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Aug 2017 23:50:04 GMT",
"version": "v2"
}
] | 2017-08-18 | [
[
"Kastner",
"R. E.",
""
],
[
"Kauffman",
"S.",
""
]
] | It is suggested that the apparently disparate cosmological phenomena attributed to so-called 'dark matter' and 'dark energy' arise from the same fundamental physical process: the emergence, from the quantum level, of spacetime itself. This creation of spacetime results in metric expansion around mass points in addition to the usual curvature due to stress-energy sources of the gravitational field. A recent modification of Einstein's theory of general relativity by Chadwick, Hodgkinson, and McDonald incorporating spacetime expansion around mass points, which accounts well for the observed galactic rotation curves, is adduced in support of the proposal. Recent observational evidence corroborates a prediction of the model that the apparent amount of 'dark matter' increases with the age of the universe. In addition, the proposal leads to the same result for the small but nonvanishing cosmological constant, related to 'dark energy, as that of the causet model of Sorkin et al. |
0802.1398 | Parthasarathi Majumdar | Parthasarathi Majumdar | Holography, CFT and Black Hole Entropy | 17 pages Latex2e with 3 eps figures; based on invited lectures given
at the Platinum Jubilee International Conference on Theoretical Physics at
ISI, Kolkata, India, December 2007 and the International Conference on
Quantum Gauge Theories at the SNBNCBS, Kolkata, India, January 2008 | null | null | null | gr-qc | null | Aspects of holography or dimensional reduction in gravitational physics are
discussed with reference to black hole thermodynamics. Degrees of freedom
living on Isolated Horizons (as a model for macroscopic, generic, eternal black
hole horizons) are argued to be topological in nature and counted, using their
relation to two dimensional conformal field theories. This leads to the
microcanonical entropy of these black holes having the Bekenstein-Hawking form
together with finite, unambigious {\it quantum spacetime} corrections. Another
aspect of holography ensues for radiant black holes treated as a standard
canonical ensemble with Isolated Horizons as the mean (equilibrium)
configuration. This is shown to yield a universal criterion for thermal
stability of generic radiant black holes, as a lower bound on the mass of the
equilibrium isolated horizon in terms of its microcanonical entropy. Saturation
of the bound occurs at a phase boundary separating thermally stable and
unstable phases with symptoms of a first order phase transition.
| [
{
"created": "Mon, 11 Feb 2008 10:05:29 GMT",
"version": "v1"
}
] | 2008-02-12 | [
[
"Majumdar",
"Parthasarathi",
""
]
] | Aspects of holography or dimensional reduction in gravitational physics are discussed with reference to black hole thermodynamics. Degrees of freedom living on Isolated Horizons (as a model for macroscopic, generic, eternal black hole horizons) are argued to be topological in nature and counted, using their relation to two dimensional conformal field theories. This leads to the microcanonical entropy of these black holes having the Bekenstein-Hawking form together with finite, unambigious {\it quantum spacetime} corrections. Another aspect of holography ensues for radiant black holes treated as a standard canonical ensemble with Isolated Horizons as the mean (equilibrium) configuration. This is shown to yield a universal criterion for thermal stability of generic radiant black holes, as a lower bound on the mass of the equilibrium isolated horizon in terms of its microcanonical entropy. Saturation of the bound occurs at a phase boundary separating thermally stable and unstable phases with symptoms of a first order phase transition. |
1906.10735 | Laura Bernard | Laura Bernard | Dipolar tidal effects in scalar-tensor theories | 6 pages, v2: typos + errors in Eqs. (7), (8), (13)-(17) corrected | Phys. Rev. D 101, 021501 (2020) | 10.1103/PhysRevD.101.021501 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The inclusion of finite-size effects in the gravitational waveform templates
allows not only to constrain the internal structure of compact objects, but to
test deviations from general relativity. Here, we address the problem of tidal
effects in massless scalar-tensor theories. We introduce a new class of
scalar-type tidal Love numbers due to the presence of a time-varying scalar
dipole moment. We compute the leading-order tidal contribution in the
conservative dynamics and for the first time in the wave generation for
quasi-circular orbits. Importantly, we show that in a system dominated by
dipolar emission, such tidal effects may be detectable by LISA or third
generation detectors.
| [
{
"created": "Tue, 25 Jun 2019 19:31:25 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Mar 2023 10:30:58 GMT",
"version": "v2"
}
] | 2023-03-02 | [
[
"Bernard",
"Laura",
""
]
] | The inclusion of finite-size effects in the gravitational waveform templates allows not only to constrain the internal structure of compact objects, but to test deviations from general relativity. Here, we address the problem of tidal effects in massless scalar-tensor theories. We introduce a new class of scalar-type tidal Love numbers due to the presence of a time-varying scalar dipole moment. We compute the leading-order tidal contribution in the conservative dynamics and for the first time in the wave generation for quasi-circular orbits. Importantly, we show that in a system dominated by dipolar emission, such tidal effects may be detectable by LISA or third generation detectors. |
gr-qc/9607079 | Andrew Chamblin | A. Chamblin (Institute for Theoretical Physics, UCSB), G.W. Gibbons
(DAMTP, University of Cambridge) | Nucleating Black Holes via Non-Orientable Instantons | 27 pages LaTeX, minor typos are corrected | Phys.Rev.D55:2177-2185,1997 | 10.1103/PhysRevD.55.2177 | ITP-96-67, DAMTP R96/37 | gr-qc hep-th | null | We extend the analysis of black hole pair creation to include non- orientable
instantons. We classify these instantons in terms of their fundamental
symmetries and orientations. Many of these instantons admit the pin structure
which corresponds to the fermions actually observed in nature, and so the
natural objection that these manifolds do not admit spin structure may not be
relevant. Furthermore, we analyse the thermodynamical properties of
non-orientable black holes and find that in the non-extreme case, there are
interesting modifications of the usual formulae for temperature and entropy.
| [
{
"created": "Thu, 1 Aug 1996 01:00:57 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Aug 1996 04:04:31 GMT",
"version": "v2"
}
] | 2009-10-07 | [
[
"Chamblin",
"A.",
"",
"Institute for Theoretical Physics, UCSB"
],
[
"Gibbons",
"G. W.",
"",
"DAMTP, University of Cambridge"
]
] | We extend the analysis of black hole pair creation to include non- orientable instantons. We classify these instantons in terms of their fundamental symmetries and orientations. Many of these instantons admit the pin structure which corresponds to the fermions actually observed in nature, and so the natural objection that these manifolds do not admit spin structure may not be relevant. Furthermore, we analyse the thermodynamical properties of non-orientable black holes and find that in the non-extreme case, there are interesting modifications of the usual formulae for temperature and entropy. |
1511.09000 | Liberato Pizza | Elmo Benedetto, Antonio Feoli, Liberato Pizza | A trace of inflation in the local behavior of cosmological constant | 3 pages, 3 figures. Accepted for publication in Astrophysics and
Space Science (ASTR-D-15-00733) | null | 10.1007/s10509-015-2587-x | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Assuming the existence of a cosmological constant depending on time, we study
the evolution of this field in a local region of spacetime. Solving the
standard equations of Einstein Relativity in the weak field approximation we
find two asymptotes in the behavior of the cosmological constant. Their meaning
is the existence of an inflationary era both in the far past and in the future.
A trace of the initial acceleration of the Universe can be found also in the
local behavior of cosmological constant.
| [
{
"created": "Sun, 29 Nov 2015 12:10:12 GMT",
"version": "v1"
}
] | 2015-12-09 | [
[
"Benedetto",
"Elmo",
""
],
[
"Feoli",
"Antonio",
""
],
[
"Pizza",
"Liberato",
""
]
] | Assuming the existence of a cosmological constant depending on time, we study the evolution of this field in a local region of spacetime. Solving the standard equations of Einstein Relativity in the weak field approximation we find two asymptotes in the behavior of the cosmological constant. Their meaning is the existence of an inflationary era both in the far past and in the future. A trace of the initial acceleration of the Universe can be found also in the local behavior of cosmological constant. |
1805.04718 | Roman Konoplya | R. A. Konoplya | How to tell the shape of a wormhole by its quasinormal modes | 8 pages, revtex4, 1 figure; version accepted for publication in
Physics Letters B | null | 10.1016/j.physletb.2018.07.025 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Here we shall show how to reconstruct the shape function of a spherically
symmetric traversable Lorenzian wormhole near its throat if one knows high
frequency quasinormal modes of the wormhole. The wormhole spacetime is given by
the Morris-Thorne ansatz. The solution to the inverse problem via fitting of
the parameters within the WKB approach is unique for arbitrary tideless
wormholes and some wormholes with non-zero tidal effects, but this is not so
for arbitrary wormholes. As examples, we reproduce the near throat geometries
of the Bronnikov-Ellis and tideless Morris-Thorne metrics by their quasinormal
modes at high multipole numbers $\ell$.
| [
{
"created": "Sat, 12 May 2018 13:13:49 GMT",
"version": "v1"
},
{
"created": "Wed, 16 May 2018 11:34:45 GMT",
"version": "v2"
},
{
"created": "Wed, 11 Jul 2018 22:30:49 GMT",
"version": "v3"
}
] | 2018-07-25 | [
[
"Konoplya",
"R. A.",
""
]
] | Here we shall show how to reconstruct the shape function of a spherically symmetric traversable Lorenzian wormhole near its throat if one knows high frequency quasinormal modes of the wormhole. The wormhole spacetime is given by the Morris-Thorne ansatz. The solution to the inverse problem via fitting of the parameters within the WKB approach is unique for arbitrary tideless wormholes and some wormholes with non-zero tidal effects, but this is not so for arbitrary wormholes. As examples, we reproduce the near throat geometries of the Bronnikov-Ellis and tideless Morris-Thorne metrics by their quasinormal modes at high multipole numbers $\ell$. |
gr-qc/0105043 | Juan M. Aguirregabiria | J. M. Aguirregabiria and Ll. Bel | Extreme objects with arbitrary large mass, or density, and arbitrary
size | 20 pages, 6 figures. Fixed one reference. Added a new equation | Gen.Rel.Grav. 33 (2001) 2049-2074 | 10.1023/A:1013059228577 | null | gr-qc | null | We consider a generalization of the interior Schwarzschild solution that we
match to the exterior one to build global C^1 models that can have arbitrary
large mass, or density, with arbitrary size. This is possible because of a new
insight into the problem of localizing the center of symmetry of the models and
the use of principal transformations to understand the structure of space.
| [
{
"created": "Mon, 14 May 2001 08:54:32 GMT",
"version": "v1"
},
{
"created": "Wed, 23 May 2001 08:39:59 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Aguirregabiria",
"J. M.",
""
],
[
"Bel",
"Ll.",
""
]
] | We consider a generalization of the interior Schwarzschild solution that we match to the exterior one to build global C^1 models that can have arbitrary large mass, or density, with arbitrary size. This is possible because of a new insight into the problem of localizing the center of symmetry of the models and the use of principal transformations to understand the structure of space. |
0906.3690 | Leonardo Fernandez-Jambrina | F.J. Chinea, L. Fern\'andez-Jambrina | Surface densities in General Relativity | 7 pp., Proceedings of ERE'93 | Relativity in General, Eds: J. Diaz Alonso y M. Lorente Paramo.
Ed. Frontieres, Gif-sur-Yvette, France, 273-277 (1994) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this lecture we deal with the construction of surface densities for the
angular momentum of the sources of asymptotically flat vacuum stationary
axisymmetric spacetimes. These sources arise from the discontinuities of the
twist potential. The result will be applied to the Kerr metric to obtain an
integrable density which can be viewed as the regularized version of the
density obtained using other formalisms.
| [
{
"created": "Fri, 19 Jun 2009 19:16:47 GMT",
"version": "v1"
}
] | 2009-06-22 | [
[
"Chinea",
"F. J.",
""
],
[
"Fernández-Jambrina",
"L.",
""
]
] | In this lecture we deal with the construction of surface densities for the angular momentum of the sources of asymptotically flat vacuum stationary axisymmetric spacetimes. These sources arise from the discontinuities of the twist potential. The result will be applied to the Kerr metric to obtain an integrable density which can be viewed as the regularized version of the density obtained using other formalisms. |
1012.4530 | Dipongkar Talukder | Dipongkar Talukder, Sanjit Mitra and Sukanta Bose | Multibaseline gravitational wave radiometry | 17 pages and 19 figures | Phys.Rev.D83:063002,2011 | 10.1103/PhysRevD.83.063002 | LIGO Document Number P1000123 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a statistic for the detection of stochastic gravitational wave
backgrounds (SGWBs) using radiometry with a network of multiple baselines. We
also quantitatively compare the sensitivities of existing baselines and their
network to SGWBs. We assess how the measurement accuracy of signal parameters,
e.g., the sky position of a localized source, can improve when using a network
of baselines, as compared to any of the single participating baselines. The
search statistic itself is derived from the likelihood ratio of the cross
correlation of the data across all possible baselines in a detector network and
is optimal in Gaussian noise. Specifically, it is the likelihood ratio
maximized over the strength of the SGWB, and is called the maximized-likelihood
ratio (MLR). One of the main advantages of using the MLR over past search
strategies for inferring the presence or absence of a signal is that the former
does not require the deconvolution of the cross correlation statistic.
Therefore, it does not suffer from errors inherent to the deconvolution
procedure and is especially useful for detecting weak sources. In the limit of
a single baseline, it reduces to the detection statistic studied by Ballmer
[Class. Quant. Grav. 23, S179 (2006)] and Mitra et al. [Phys. Rev. D 77, 042002
(2008)]. Unlike past studies, here the MLR statistic enables us to compare
quantitatively the performances of a variety of baselines searching for a SGWB
signal in (simulated) data. Although we use simulated noise and SGWB signals
for making these comparisons, our method can be straightforwardly applied on
real data.
| [
{
"created": "Tue, 21 Dec 2010 02:03:03 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Mar 2011 02:17:37 GMT",
"version": "v2"
}
] | 2015-03-17 | [
[
"Talukder",
"Dipongkar",
""
],
[
"Mitra",
"Sanjit",
""
],
[
"Bose",
"Sukanta",
""
]
] | We present a statistic for the detection of stochastic gravitational wave backgrounds (SGWBs) using radiometry with a network of multiple baselines. We also quantitatively compare the sensitivities of existing baselines and their network to SGWBs. We assess how the measurement accuracy of signal parameters, e.g., the sky position of a localized source, can improve when using a network of baselines, as compared to any of the single participating baselines. The search statistic itself is derived from the likelihood ratio of the cross correlation of the data across all possible baselines in a detector network and is optimal in Gaussian noise. Specifically, it is the likelihood ratio maximized over the strength of the SGWB, and is called the maximized-likelihood ratio (MLR). One of the main advantages of using the MLR over past search strategies for inferring the presence or absence of a signal is that the former does not require the deconvolution of the cross correlation statistic. Therefore, it does not suffer from errors inherent to the deconvolution procedure and is especially useful for detecting weak sources. In the limit of a single baseline, it reduces to the detection statistic studied by Ballmer [Class. Quant. Grav. 23, S179 (2006)] and Mitra et al. [Phys. Rev. D 77, 042002 (2008)]. Unlike past studies, here the MLR statistic enables us to compare quantitatively the performances of a variety of baselines searching for a SGWB signal in (simulated) data. Although we use simulated noise and SGWB signals for making these comparisons, our method can be straightforwardly applied on real data. |
2006.06461 | Timothy Anson | Timothy Anson, Eugeny Babichev, Christos Charmousis, Mokhtar Hassaine | Disforming the Kerr metric | 20 pages, 3 figures, v3: minor changes, matches published version | JHEP01(2021)018 | 10.1007/JHEP01(2021)018 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Starting from a recently constructed stealth Kerr solution of higher order
scalar tensor theory involving scalar hair, we analytically construct disformal
versions of the Kerr spacetime with a constant degree of disformality and a
regular scalar field. While the disformed metric has only a ring singularity
and asymptotically is quite similar to Kerr, it is found to be neither Ricci
flat nor circular. Non-circularity has far reaching consequences on the
structure of the solution. As we approach the rotating compact object from
asymptotic infinity we find a static limit ergosurface similar to the Kerr
spacetime with an enclosed ergoregion. However, the stationary limit of
infalling observers is found to be a timelike hypersurface. A candidate event
horizon is found in the interior of this stationary limit surface. It is a null
hypersurface generated by a null congruence of light rays which are no longer
Killing vectors. Under a mild regularity assumption, we find that the candidate
surface is indeed an event horizon and the disformed Kerr metric is therefore a
black hole quite distinct from the Kerr solution.
| [
{
"created": "Thu, 11 Jun 2020 14:14:52 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Jun 2020 15:11:34 GMT",
"version": "v2"
},
{
"created": "Wed, 6 Jan 2021 11:35:01 GMT",
"version": "v3"
}
] | 2021-01-07 | [
[
"Anson",
"Timothy",
""
],
[
"Babichev",
"Eugeny",
""
],
[
"Charmousis",
"Christos",
""
],
[
"Hassaine",
"Mokhtar",
""
]
] | Starting from a recently constructed stealth Kerr solution of higher order scalar tensor theory involving scalar hair, we analytically construct disformal versions of the Kerr spacetime with a constant degree of disformality and a regular scalar field. While the disformed metric has only a ring singularity and asymptotically is quite similar to Kerr, it is found to be neither Ricci flat nor circular. Non-circularity has far reaching consequences on the structure of the solution. As we approach the rotating compact object from asymptotic infinity we find a static limit ergosurface similar to the Kerr spacetime with an enclosed ergoregion. However, the stationary limit of infalling observers is found to be a timelike hypersurface. A candidate event horizon is found in the interior of this stationary limit surface. It is a null hypersurface generated by a null congruence of light rays which are no longer Killing vectors. Under a mild regularity assumption, we find that the candidate surface is indeed an event horizon and the disformed Kerr metric is therefore a black hole quite distinct from the Kerr solution. |
2407.06009 | Lodovico Capuano | Lodovico Capuano, Luca Santoni, Enrico Barausse | Perturbations of the Vaidya metric in the frequency domain: Quasi-normal
modes and tidal response | 19 pages, 4 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The mass of a black hole can dynamically evolve due to various physical
processes, such as for instance accretion, Hawking radiation, absorption of
gravitational/electromagnetic waves, superradiance, etc. This evolution can
have an impact on astrophysical observables, like the ringdown gravitational
signal. An effective description of a spherically symmetric black hole with
evolving mass is provided by the Vaidya metric. In our investigation, we
explore the dynamics of linear perturbations on this background, assuming a
constant rate of change for the mass. Despite the time-dependent background, a
judicious change of coordinates allows us to treat the perturbations in the
frequency domain, and to compute explicitly the quasi-normal modes and the
tidal Love numbers.
| [
{
"created": "Mon, 8 Jul 2024 15:00:48 GMT",
"version": "v1"
}
] | 2024-07-09 | [
[
"Capuano",
"Lodovico",
""
],
[
"Santoni",
"Luca",
""
],
[
"Barausse",
"Enrico",
""
]
] | The mass of a black hole can dynamically evolve due to various physical processes, such as for instance accretion, Hawking radiation, absorption of gravitational/electromagnetic waves, superradiance, etc. This evolution can have an impact on astrophysical observables, like the ringdown gravitational signal. An effective description of a spherically symmetric black hole with evolving mass is provided by the Vaidya metric. In our investigation, we explore the dynamics of linear perturbations on this background, assuming a constant rate of change for the mass. Despite the time-dependent background, a judicious change of coordinates allows us to treat the perturbations in the frequency domain, and to compute explicitly the quasi-normal modes and the tidal Love numbers. |
2102.05881 | Jinsong Yang | Jinsong Yang, Cong Zhang, Yongge Ma | Relating spin-foam to canonical loop quantum gravity by graphical
calculus | 19 pages | Phys. Rev. D 104, 044025 (2021) | 10.1103/PhysRevD.104.044025 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The graphical calculus method is generalized to study the relation between
covariant and canonical dynamics of loop quantum gravity. On one hand, a
graphical derivation of the partition function of the generalized Euclidean
Engle-Pereira-Rovelli-Livine (EPRL) spin-foam model is presented. On the other
hand, the action of a Euclidean Hamiltonian constraint operator on certain spin
network states is calculated by graphical method. It turns out that the EPRL
model can provide a rigging map such that the Hamiltonian constraint operator
is weakly satisfied on certain physical states for the Immirzi parameter
$\beta=1$. In this sense, the quantum dynamics between the covariant and
canonical formulations are consistent to each other.
| [
{
"created": "Thu, 11 Feb 2021 08:00:42 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Feb 2021 11:24:11 GMT",
"version": "v2"
},
{
"created": "Sat, 14 Aug 2021 06:58:51 GMT",
"version": "v3"
}
] | 2021-08-17 | [
[
"Yang",
"Jinsong",
""
],
[
"Zhang",
"Cong",
""
],
[
"Ma",
"Yongge",
""
]
] | The graphical calculus method is generalized to study the relation between covariant and canonical dynamics of loop quantum gravity. On one hand, a graphical derivation of the partition function of the generalized Euclidean Engle-Pereira-Rovelli-Livine (EPRL) spin-foam model is presented. On the other hand, the action of a Euclidean Hamiltonian constraint operator on certain spin network states is calculated by graphical method. It turns out that the EPRL model can provide a rigging map such that the Hamiltonian constraint operator is weakly satisfied on certain physical states for the Immirzi parameter $\beta=1$. In this sense, the quantum dynamics between the covariant and canonical formulations are consistent to each other. |
1302.1014 | Jian-Yang Zhu | Xiao-Jun Yue and Jian-Yang Zhu | Loop Quantum Cosmology of Bianchi I Model in $\bar{\mu}$ and
$\bar{\mu}'$ Schemes with Higher Order Holonomy Corrections | 16 pages, 3 figures | Class. Quantum Grav. 31 (2014) 045008 | 10.1088/0264-9381/31/4/045008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The detailed formulation of loop quantum cosmology with higher order holonomy
corrections has been constructed recently in the homogeneous and isotropic
spacetime, yet it is important to extend the higher order holonomy corrections
to include the effects of anisotropy which typically grow during the collapsing
phase. In this paper we investigate the Bianchi I model in $\bar{\mu}'$ scheme
which truly captures the regularization of the Hamiltonian constraint. To
compare with the earlier works and provide a comparison with the $\bar{\mu}'$
scheme, we also investigate the $\bar{\mu}$ scheme although it has many
disadvantages. First we construct the effective dynamics with higher order
holonomy corrections in a massless scalar field, then we extend it to the
inclusion of arbitrary matter. Besides that, we also analyze the behavior of
the anisotropy during the evolution of the universe. We find that in the
$\bar{\mu}'$ scheme, the singularity is never approached and the quantum bounce
is generic as in the isotropic case, regardless of the order of the holonomy
corrections. Some differences in the bouncing phase of the two schemes are also
found out. It is also shown that in the two schemes the behavior of the
anisotropy is not the same before and after the bounce.
| [
{
"created": "Tue, 5 Feb 2013 12:39:33 GMT",
"version": "v1"
},
{
"created": "Fri, 31 Jan 2014 17:09:51 GMT",
"version": "v2"
}
] | 2015-06-12 | [
[
"Yue",
"Xiao-Jun",
""
],
[
"Zhu",
"Jian-Yang",
""
]
] | The detailed formulation of loop quantum cosmology with higher order holonomy corrections has been constructed recently in the homogeneous and isotropic spacetime, yet it is important to extend the higher order holonomy corrections to include the effects of anisotropy which typically grow during the collapsing phase. In this paper we investigate the Bianchi I model in $\bar{\mu}'$ scheme which truly captures the regularization of the Hamiltonian constraint. To compare with the earlier works and provide a comparison with the $\bar{\mu}'$ scheme, we also investigate the $\bar{\mu}$ scheme although it has many disadvantages. First we construct the effective dynamics with higher order holonomy corrections in a massless scalar field, then we extend it to the inclusion of arbitrary matter. Besides that, we also analyze the behavior of the anisotropy during the evolution of the universe. We find that in the $\bar{\mu}'$ scheme, the singularity is never approached and the quantum bounce is generic as in the isotropic case, regardless of the order of the holonomy corrections. Some differences in the bouncing phase of the two schemes are also found out. It is also shown that in the two schemes the behavior of the anisotropy is not the same before and after the bounce. |
1811.07500 | Vladimir Folomeev | Vladimir Dzhunushaliev, Vladimir Folomeev | Dirac stars supported by nonlinear spinor fields | 8 pages, 4 figures, minor corrections to content, new reference
added, version published in PRD | Phys. Rev. D 99, 084030 (2019) | 10.1103/PhysRevD.99.084030 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study configurations consisting of a gravitating spinor field $\psi$ with
a nonlinearity of the type $\lambda\left(\bar\psi\psi\right)^2$. To ensure
spherical symmetry of the configurations, we use two spin-$\frac{1}{2}$ fields
forming a spin singlet. For such systems, we find regular stationary
asymptotically flat solutions describing compact objects. For negative values
of the coupling constant $\lambda$, it is shown that, by choosing physically
reasonable values of this constant, it is possible to obtain configurations
with masses comparable to the Chandrasekhar mass. It enables us to speak of an
astrophysical interpretation of the obtained systems, regarding them as Dirac
stars.
| [
{
"created": "Mon, 19 Nov 2018 04:58:53 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Apr 2019 04:30:07 GMT",
"version": "v2"
}
] | 2019-04-19 | [
[
"Dzhunushaliev",
"Vladimir",
""
],
[
"Folomeev",
"Vladimir",
""
]
] | We study configurations consisting of a gravitating spinor field $\psi$ with a nonlinearity of the type $\lambda\left(\bar\psi\psi\right)^2$. To ensure spherical symmetry of the configurations, we use two spin-$\frac{1}{2}$ fields forming a spin singlet. For such systems, we find regular stationary asymptotically flat solutions describing compact objects. For negative values of the coupling constant $\lambda$, it is shown that, by choosing physically reasonable values of this constant, it is possible to obtain configurations with masses comparable to the Chandrasekhar mass. It enables us to speak of an astrophysical interpretation of the obtained systems, regarding them as Dirac stars. |
2108.10276 | Sergey Yu. Vernov | Vsevolod R. Ivanov and Sergey Yu. Vernov | Integrable modified gravity cosmological models with an additional
scalar field | 11 pages, 3 figures, v2: minor corrections, references are added, to
appear in EPJC | Eur. Phys. J. C 81 (2021) 985 | 10.1140/epjc/s10052-021-09792-4 | null | gr-qc astro-ph.CO math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider modified gravity cosmological models that can be transformed into
two-field chiral cosmological models by the conformal metric transformation.
For the $R^2$ gravity model with an additional scalar field and the
corresponding two-field model with the cosmological constant and nonstandard
kinetic part of the action, the general solutions have been obtained in the
spatially flat FLRW metric. We analyze the correspondence of the cosmic time
solutions obtained and different possible evolutions of the Hubble parameters
in the Einstein and Jordan frames.
| [
{
"created": "Mon, 23 Aug 2021 16:27:25 GMT",
"version": "v1"
},
{
"created": "Sun, 31 Oct 2021 19:07:26 GMT",
"version": "v2"
}
] | 2021-11-11 | [
[
"Ivanov",
"Vsevolod R.",
""
],
[
"Vernov",
"Sergey Yu.",
""
]
] | We consider modified gravity cosmological models that can be transformed into two-field chiral cosmological models by the conformal metric transformation. For the $R^2$ gravity model with an additional scalar field and the corresponding two-field model with the cosmological constant and nonstandard kinetic part of the action, the general solutions have been obtained in the spatially flat FLRW metric. We analyze the correspondence of the cosmic time solutions obtained and different possible evolutions of the Hubble parameters in the Einstein and Jordan frames. |
2305.19057 | Yongqiang Wang | X. E. Wang | From Bardeen-boson stars to black holes without event horizon | 10 pages, 3 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a talk given in 2013, S. Hawking conjectured that the event horizon of
black holes does not exist and suggested redefining black holes as bound states
of the gravitational field. Inspired by this idea, we investigated the coupling
of the Bardeen action and a complex scalar field model. Numerically, we
obtained a class of boson stars solutions with the magnetic monopole charge
$q$. When the constant $q$ exceeds a certain threshold, we observed that as the
frequency approaches zero, a critical position $r_c$ emerges where the scalar
field concentrates within its interior. Outside this critical position, these
boson star solutions tend to infinitely approach what is known as an extreme
black hole. However, there is no event horizon present. While our results are
model-dependent and their generality remains uncertain, they align well with
Hawking's conjecture that real, regular black holes do not have an event
horizon and provided valuable insights into the understanding and development
of concepts such as fuzzballs, firewalls and black hole soft hairs.
| [
{
"created": "Tue, 30 May 2023 14:19:29 GMT",
"version": "v1"
}
] | 2023-05-31 | [
[
"Wang",
"X. E.",
""
]
] | In a talk given in 2013, S. Hawking conjectured that the event horizon of black holes does not exist and suggested redefining black holes as bound states of the gravitational field. Inspired by this idea, we investigated the coupling of the Bardeen action and a complex scalar field model. Numerically, we obtained a class of boson stars solutions with the magnetic monopole charge $q$. When the constant $q$ exceeds a certain threshold, we observed that as the frequency approaches zero, a critical position $r_c$ emerges where the scalar field concentrates within its interior. Outside this critical position, these boson star solutions tend to infinitely approach what is known as an extreme black hole. However, there is no event horizon present. While our results are model-dependent and their generality remains uncertain, they align well with Hawking's conjecture that real, regular black holes do not have an event horizon and provided valuable insights into the understanding and development of concepts such as fuzzballs, firewalls and black hole soft hairs. |
2112.04347 | Masum Murshid | Masum Murshid, Nilofar Rahman, Irina Radinschi and Mehedi Kalam | Analytical model of low mass strange stars in 2+1 spacetime | null | null | null | null | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | The low mass compact stars are quite fascinating objects to study for their
enigmatic behaviour. In this paper, we have modeled this kind of low mass
strange stars based on the Heintzmann ansatz (H. Heintzmann., Zeitschrift f\"ur
Physik, vol.228, 489, 1969.) in $(2+1)$ dimension. Attractive anisotropic force
plays a significant role to restrict the upper mass limit (which is
comparatively low) of the strange star. We have applied our model to some low
mass strange stars. Our model could be useful to predict the important
parameters of the low mass strange stars.
| [
{
"created": "Wed, 8 Dec 2021 15:55:04 GMT",
"version": "v1"
}
] | 2021-12-09 | [
[
"Murshid",
"Masum",
""
],
[
"Rahman",
"Nilofar",
""
],
[
"Radinschi",
"Irina",
""
],
[
"Kalam",
"Mehedi",
""
]
] | The low mass compact stars are quite fascinating objects to study for their enigmatic behaviour. In this paper, we have modeled this kind of low mass strange stars based on the Heintzmann ansatz (H. Heintzmann., Zeitschrift f\"ur Physik, vol.228, 489, 1969.) in $(2+1)$ dimension. Attractive anisotropic force plays a significant role to restrict the upper mass limit (which is comparatively low) of the strange star. We have applied our model to some low mass strange stars. Our model could be useful to predict the important parameters of the low mass strange stars. |
gr-qc/9311024 | Sakai | Nobuyuki Sakai and Kei-ichi Maeda | Junction Conditions of Friedmann-Robertson-Walker Space-Times | 7 pages, LaTeX, figures are not included (available on request by
regular mail), WU-AP/31/93 | Phys.Rev.D50:5425-5428,1994 | 10.1103/PhysRevD.50.5425 | null | gr-qc | null | We complete a classification of junctions of two Friedmann-Robertson-Walker
space-times bounded by a spherical thin wall. Our analysis covers super-horizon
bubbles and thus complements the previous work of Berezin, Kuzumin and Tkachev.
Contrary to sub-horizon bubbles, various topology types for super-horizon
bubbles are possible, regardless of the sign of the extrinsic curvature. We
also derive a formula for the peculiar velocity of a domain wall for all types
of junction.
| [
{
"created": "Mon, 15 Nov 1993 10:41:52 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Aug 1994 14:23:03 GMT",
"version": "v2"
}
] | 2010-11-01 | [
[
"Sakai",
"Nobuyuki",
""
],
[
"Maeda",
"Kei-ichi",
""
]
] | We complete a classification of junctions of two Friedmann-Robertson-Walker space-times bounded by a spherical thin wall. Our analysis covers super-horizon bubbles and thus complements the previous work of Berezin, Kuzumin and Tkachev. Contrary to sub-horizon bubbles, various topology types for super-horizon bubbles are possible, regardless of the sign of the extrinsic curvature. We also derive a formula for the peculiar velocity of a domain wall for all types of junction. |
gr-qc/0102113 | Brandon Carter | B. Carter | Interaction of gravitational waves with an elastic solid medium | 14 pages TeX file of contrib. to proc. Gravitational Radiation, Les
Houches 1982, ed N. Deruelle, T. Piran, 455-464 (North Holland, Amsterdam,
1983) | null | null | null | gr-qc | null | Contents. 1. Introduction. 2. Kinematics of a Material Medium: Material
Representation. 3. Kinematics of a Material Medium: Convected Differentials. 4.
Kinematics of a Perfect Elastic Medium. 5. Small Gravitational Perturbations of
an Elastic Medium.
| [
{
"created": "Wed, 28 Feb 2001 16:02:19 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Carter",
"B.",
""
]
] | Contents. 1. Introduction. 2. Kinematics of a Material Medium: Material Representation. 3. Kinematics of a Material Medium: Convected Differentials. 4. Kinematics of a Perfect Elastic Medium. 5. Small Gravitational Perturbations of an Elastic Medium. |
gr-qc/0509110 | Tiberiu Harko | C. G. Boehmer, T. Harko | Does the cosmological constant imply the existence of a minimum mass? | 8 pages, no figures, accepted for publication in PLB | Phys.Lett. B630 (2005) 73-77 | 10.1016/j.physletb.2005.09.071 | Preprint ESI 1712, TUW-05-14 | gr-qc astro-ph hep-th | null | We show that in the framework of the classical general relativity the
presence of a positive cosmological constant implies the existence of a minimal
mass and of a minimal density in nature. These results rigorously follow from
the generalized Buchdahl inequality in the presence of a cosmological constant.
| [
{
"created": "Wed, 28 Sep 2005 02:04:14 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Oct 2005 18:13:52 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Boehmer",
"C. G.",
""
],
[
"Harko",
"T.",
""
]
] | We show that in the framework of the classical general relativity the presence of a positive cosmological constant implies the existence of a minimal mass and of a minimal density in nature. These results rigorously follow from the generalized Buchdahl inequality in the presence of a cosmological constant. |
1909.05154 | Susobhan Mandal | Susobhan Mandal | Existence of conserved quantities and their algebra in curved spacetime | 19 pages. Typos are corrected and title is changed | null | 10.1142/S0217751X20501626 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In General Relativity, finding out the geodesics of a given spacetime
manifold is an important task because it determines which classical processes
are dynamically forbidden. Conserved quantities play an important role in
solving geodesic equations of a general spacetime manifold. Furthermore,
knowing all possible conserved quantities of a system tells about the hidden
symmetries of that system since, conserved quantities are deeply connected with
the symmetries of the system, which are very important in their own right.
Conserved quantities are also useful to capture certain features of spacetime
manifold for an asymptotic observer. In this article, we show the existence of
these conserved charges and their algebra for a class of dynamical systems in a
generic curved spacetime.
| [
{
"created": "Mon, 8 Jul 2019 11:44:15 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Sep 2019 06:10:09 GMT",
"version": "v2"
},
{
"created": "Thu, 4 Jun 2020 08:55:22 GMT",
"version": "v3"
}
] | 2020-09-24 | [
[
"Mandal",
"Susobhan",
""
]
] | In General Relativity, finding out the geodesics of a given spacetime manifold is an important task because it determines which classical processes are dynamically forbidden. Conserved quantities play an important role in solving geodesic equations of a general spacetime manifold. Furthermore, knowing all possible conserved quantities of a system tells about the hidden symmetries of that system since, conserved quantities are deeply connected with the symmetries of the system, which are very important in their own right. Conserved quantities are also useful to capture certain features of spacetime manifold for an asymptotic observer. In this article, we show the existence of these conserved charges and their algebra for a class of dynamical systems in a generic curved spacetime. |
2004.06102 | Simone Mastrogiovanni | S. Mastrogiovanni, D. A. Steer, M. Barsuglia | Joint tests of cosmology and modified gravity in light of GW170817 | This paper has been merged with 2004.01632 | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this Letter we constrain for the first time both cosmology and modified
gravity theories conjointly, by combining the GW and electromagnetic
observations of GW170817. We provide joint posterior distributions for the
Hubble constant $H_0$, and two physical effects typical of modified gravity:
the gravitational wave (GW) friction, encoded by the parameter $\alpha_M$, and
several GW dispersion relations. Among the results of this analysis, we can
improve by 15\% the bound of the graviton mass with respect to measurement
using the same event, but fixing $H_0$. We obtain a value of
$m^2_g=2.08_{-4.25}^{+13.90} \cdot 10^{-44} \rm{eV^2/c^4}$ at 99.7\% confidence
level (CL), when marginalising over the Hubble constant and GW friction term
$\alpha_M$. We find poor constraints on $\alpha_M$, but demonstrate that for
all the GW dispersions relations considered, including massive gravity, the GW
must be emitted $\sim$ 1.74s before the Gamma-ray burst (GRB). Furthermore, at
the GW merger peak frequency, we show that the fractional difference between
the GW group velocity and $c$ is $\lesssim 10^{-17}$.
| [
{
"created": "Mon, 13 Apr 2020 17:59:30 GMT",
"version": "v1"
},
{
"created": "Tue, 21 Apr 2020 10:40:52 GMT",
"version": "v2"
},
{
"created": "Wed, 12 Aug 2020 18:16:49 GMT",
"version": "v3"
}
] | 2020-08-14 | [
[
"Mastrogiovanni",
"S.",
""
],
[
"Steer",
"D. A.",
""
],
[
"Barsuglia",
"M.",
""
]
] | In this Letter we constrain for the first time both cosmology and modified gravity theories conjointly, by combining the GW and electromagnetic observations of GW170817. We provide joint posterior distributions for the Hubble constant $H_0$, and two physical effects typical of modified gravity: the gravitational wave (GW) friction, encoded by the parameter $\alpha_M$, and several GW dispersion relations. Among the results of this analysis, we can improve by 15\% the bound of the graviton mass with respect to measurement using the same event, but fixing $H_0$. We obtain a value of $m^2_g=2.08_{-4.25}^{+13.90} \cdot 10^{-44} \rm{eV^2/c^4}$ at 99.7\% confidence level (CL), when marginalising over the Hubble constant and GW friction term $\alpha_M$. We find poor constraints on $\alpha_M$, but demonstrate that for all the GW dispersions relations considered, including massive gravity, the GW must be emitted $\sim$ 1.74s before the Gamma-ray burst (GRB). Furthermore, at the GW merger peak frequency, we show that the fractional difference between the GW group velocity and $c$ is $\lesssim 10^{-17}$. |
gr-qc/9308020 | null | J.J.Halliwell and M.E.Ortiz | Quantum mechanical composition laws in reparameterization invariant
systems | 5 pages | Int.J.Mod.Phys.D3:195-198,1994 | 10.1142/S0218271894000277 | null | gr-qc hep-th | null | This paper gives a brief description of the derivation of a composition law
for the propagator of a relativistic particle, in a sum over histories
quantization. The extension of this derivation to the problem of finding a
composition law for quantum cosmology is also discussed. (For the proceedings
of Journees Relativistes 93)
| [
{
"created": "Fri, 20 Aug 1993 17:06:36 GMT",
"version": "v1"
}
] | 2011-04-15 | [
[
"Halliwell",
"J. J.",
""
],
[
"Ortiz",
"M. E.",
""
]
] | This paper gives a brief description of the derivation of a composition law for the propagator of a relativistic particle, in a sum over histories quantization. The extension of this derivation to the problem of finding a composition law for quantum cosmology is also discussed. (For the proceedings of Journees Relativistes 93) |
1103.3554 | Hossein Farajollahi | H. Farajollahi, A. Ravanpak, G. F. Fadakar | The universe dynamics in the tachyon cosmology with non-minimal coupling
to matter | 14 pages, 11 figures | Mod. Phys. Lett. A, Vol. 26, No. 15 (2011) pp. 1125-1135 | 10.1142/S0217732311035523 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, the tachyon cosmology has been represented as dark energy model to
support the current acceleration of the universe without phantom crossing. In
this paper, we study the dynamics of the tachyon cosmology in which the field
plays the role of tachyon field and also non--minimally coupled to the matter
lagrangian. The model shows current universe acceleration and also phantom
crossing in the future. Two cosmological tests are also performed to validate
the model; the difference in the distance modulus and the model independent
Cosmological Redshift Drift (CRD) test.
| [
{
"created": "Fri, 18 Mar 2011 05:06:55 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Jun 2011 07:00:49 GMT",
"version": "v2"
}
] | 2015-05-27 | [
[
"Farajollahi",
"H.",
""
],
[
"Ravanpak",
"A.",
""
],
[
"Fadakar",
"G. F.",
""
]
] | Recently, the tachyon cosmology has been represented as dark energy model to support the current acceleration of the universe without phantom crossing. In this paper, we study the dynamics of the tachyon cosmology in which the field plays the role of tachyon field and also non--minimally coupled to the matter lagrangian. The model shows current universe acceleration and also phantom crossing in the future. Two cosmological tests are also performed to validate the model; the difference in the distance modulus and the model independent Cosmological Redshift Drift (CRD) test. |
1501.03968 | Apostolos Kuiroukidis | I. G. Contopoulos, F. P. Esposito, K. Kleidis, D. B. Papadopoulos, and
L. Witten | Generating Solutions to the Einstein Field Equations | 16 pages; submitted to IJMP D | null | 10.1142/S021827181650022X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Exact solutions to the Einstein field equations may be generated from already
existing ones (seed solutions), that admit at least one Killing vector. In this
framework, a space of potentials is introduced. By the use of symmetries in
this space, the set of potentials associated to a known solution are
transformed into a new set, either by continuous transformations or by discrete
transformations. In view of this method, and upon consideration of continuous
transformations, we arrive at some exact, stationary axisymmetric solutions to
the Einstein field equations in vacuum, that may be of geometrical or/and
physical interest.
| [
{
"created": "Fri, 16 Jan 2015 12:56:37 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Apr 2015 08:39:23 GMT",
"version": "v2"
},
{
"created": "Fri, 7 Aug 2015 17:33:48 GMT",
"version": "v3"
}
] | 2016-03-16 | [
[
"Contopoulos",
"I. G.",
""
],
[
"Esposito",
"F. P.",
""
],
[
"Kleidis",
"K.",
""
],
[
"Papadopoulos",
"D. B.",
""
],
[
"Witten",
"L.",
""
]
] | Exact solutions to the Einstein field equations may be generated from already existing ones (seed solutions), that admit at least one Killing vector. In this framework, a space of potentials is introduced. By the use of symmetries in this space, the set of potentials associated to a known solution are transformed into a new set, either by continuous transformations or by discrete transformations. In view of this method, and upon consideration of continuous transformations, we arrive at some exact, stationary axisymmetric solutions to the Einstein field equations in vacuum, that may be of geometrical or/and physical interest. |
gr-qc/9910021 | Maria Emilia | C. N. Ferreira (Depto. Campos e Particulas, CBPF), M. E. X. Guimaraes
(Depto. de Matematica, UnB) and J. A. Helayel-Neto (Depto. de Campos e
Particulas, CBPF and UCP) | Dilatonic, Current-Carrying Cosmic String | 12 pp, Latex, no figures, based on a talk given by M. E. X. Guimaraes
at the COSMO 99, 27/9 to 02/10/99, ICTP, Trieste, It | null | 10.1142/9789812792129_0038 | null | gr-qc hep-th | null | We study the implications of a scalar-tensorial gravity for the metric of an
isolated self-gravitating superconducting cosmic string. These modifications
are induced by an arbitrary coupling of a massless scalar field to the usual
tensorial field in the gravitational Lagrangian. We derive the metric in the
weak-field approximation and we analyse the behaviour of light in this
spacetime. We end with some discussions.
| [
{
"created": "Wed, 6 Oct 1999 15:59:16 GMT",
"version": "v1"
}
] | 2016-11-03 | [
[
"Ferreira",
"C. N.",
"",
"Depto. Campos e Particulas, CBPF"
],
[
"Guimaraes",
"M. E. X.",
"",
"Depto. de Matematica, UnB"
],
[
"Helayel-Neto",
"J. A.",
"",
"Depto. de Campos e\n Particulas, CBPF and UCP"
]
] | We study the implications of a scalar-tensorial gravity for the metric of an isolated self-gravitating superconducting cosmic string. These modifications are induced by an arbitrary coupling of a massless scalar field to the usual tensorial field in the gravitational Lagrangian. We derive the metric in the weak-field approximation and we analyse the behaviour of light in this spacetime. We end with some discussions. |
2105.05039 | Emil Akhmedov | E.T.Akhmedov (MIPT and ITEP) | Curved space equilibration vs. flat space thermalization (a short
review) | 15 pages | null | 10.1142/S0217732321300202 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss equilibration process in expanding universes as compared to the
thermalization process in Minkowski space--time. The final goal is to answer
the following question: Is the equilibrium reached before the rapid expansion
stops and quantum effects have a negligible effect on the background geometry
or stress--energy fluxes in a highly curved early Universe have strong effects
on the expansion rate and the equilibrium is reached only after the drastic
decrease of the space--time curvature? We argue that consideration of more
generic non--invariant states in theories with invariant actions is a necessary
ingredient to understand quantum field dynamics in strongly curved backgrounds.
We are talking about such states in which correlation functions are not
functions of such isometry invariants as geodesic distances, while having
correct UV behaviour. The reason to consider such states is the presence of IR
secular memory effects for generic time dependent backgrounds, which are
totally absent in equilibrium. These effects strongly affect the destiny of
observables in highly curved space--times.
| [
{
"created": "Sun, 9 May 2021 14:50:41 GMT",
"version": "v1"
}
] | 2021-07-21 | [
[
"Akhmedov",
"E. T.",
"",
"MIPT and ITEP"
]
] | We discuss equilibration process in expanding universes as compared to the thermalization process in Minkowski space--time. The final goal is to answer the following question: Is the equilibrium reached before the rapid expansion stops and quantum effects have a negligible effect on the background geometry or stress--energy fluxes in a highly curved early Universe have strong effects on the expansion rate and the equilibrium is reached only after the drastic decrease of the space--time curvature? We argue that consideration of more generic non--invariant states in theories with invariant actions is a necessary ingredient to understand quantum field dynamics in strongly curved backgrounds. We are talking about such states in which correlation functions are not functions of such isometry invariants as geodesic distances, while having correct UV behaviour. The reason to consider such states is the presence of IR secular memory effects for generic time dependent backgrounds, which are totally absent in equilibrium. These effects strongly affect the destiny of observables in highly curved space--times. |
1008.0971 | A. Tawfik | A. Tawfik (Egyptian Ctr. Theor. Phys., Cairo), M. Wahba (Egyptian Ctr.
Theor. Phys., Cairo), H. Mansour (Cairo U.) and T. Harko (Hong Kong U.) | Hubble Parameter in QCD Universe for finite Bulk Viscosity | 9 pages (revtex4 style), 5 figures with 8 eps graphs | Annalen Phys.522:912-923,2010 | 10.1002/andp.201000103 | ECTP-2010-07 | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the influence of the perturbative bulk viscosity on the evolution
of the Hubble parameter in the QCD era of the early Universe. For the geometry
of the Universe we assume the homogeneous and isotropic
Friedmann-Lemaitre-Robertson-Walker metric, while the background matter is
assumed to be characterized by barotropic equations of state, obtained from
recent lattice QCD simulations, and heavy--ion collisions, respectively. Taking
into account a perturbative form for the bulk viscosity coefficient, we obtain
the evolution of the Hubble parameter, and we compare it with its evolution for
an ideal (non-viscous) cosmological matter. A numerical solution for the
viscous QCD plasma in the framework of the causal Israel-Stewart thermodynamics
is also obtained. Both the perturbative approach and the numerical solution
qualitatively agree in reproducing the viscous corrections to the Hubble
parameter, which in the viscous case turns out to be slightly different as
compared to the non--viscous case. Our results are strictly limited within a
very narrow temperature- or time-interval in the QCD era, where the quark-gluon
plasma is likely dominant.
| [
{
"created": "Thu, 5 Aug 2010 13:41:36 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Sep 2010 14:19:09 GMT",
"version": "v2"
}
] | 2010-11-24 | [
[
"Tawfik",
"A.",
"",
"Egyptian Ctr. Theor. Phys., Cairo"
],
[
"Wahba",
"M.",
"",
"Egyptian Ctr.\n Theor. Phys., Cairo"
],
[
"Mansour",
"H.",
"",
"Cairo U."
],
[
"Harko",
"T.",
"",
"Hong Kong U."
]
] | We consider the influence of the perturbative bulk viscosity on the evolution of the Hubble parameter in the QCD era of the early Universe. For the geometry of the Universe we assume the homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker metric, while the background matter is assumed to be characterized by barotropic equations of state, obtained from recent lattice QCD simulations, and heavy--ion collisions, respectively. Taking into account a perturbative form for the bulk viscosity coefficient, we obtain the evolution of the Hubble parameter, and we compare it with its evolution for an ideal (non-viscous) cosmological matter. A numerical solution for the viscous QCD plasma in the framework of the causal Israel-Stewart thermodynamics is also obtained. Both the perturbative approach and the numerical solution qualitatively agree in reproducing the viscous corrections to the Hubble parameter, which in the viscous case turns out to be slightly different as compared to the non--viscous case. Our results are strictly limited within a very narrow temperature- or time-interval in the QCD era, where the quark-gluon plasma is likely dominant. |
gr-qc/9303002 | Tevian Dray | Tevian Dray, Corinne A. Manogue, and Robin W. Tucker | The Scalar Field Equation in the Presence of Signature Change | requires REVTeX 2.0 or 3.0 (Plain TeX version available on request),
4 pages by default (12 in preprint style), no figures | Phys.Rev. D48 (1993) 2587-2590 | 10.1103/PhysRevD.48.2587 | null | gr-qc hep-th | null | We consider the (massless) scalar field on a 2-dimensional manifold with
metric that changes signature from Lorentzian to Euclidean. Requiring a
conserved momentum in the spatially homogeneous case leads to a particular
choice of propagation rule. The resulting mix of positive and negative
frequencies depends only on the total (conformal) size of the spacelike regions
and not on the detailed form of the metric. Reformulating the problem using
junction conditions, we then show that the solutions obtained above are the
unique ones which satisfy the natural distributional wave equation everywhere.
We also give a variational approach, obtaining the same results from a natural
Lagrangian.
(PACS numbers 04.20.Cv and 02.40.+m.)
| [
{
"created": "Mon, 1 Mar 1993 22:45:16 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Dray",
"Tevian",
""
],
[
"Manogue",
"Corinne A.",
""
],
[
"Tucker",
"Robin W.",
""
]
] | We consider the (massless) scalar field on a 2-dimensional manifold with metric that changes signature from Lorentzian to Euclidean. Requiring a conserved momentum in the spatially homogeneous case leads to a particular choice of propagation rule. The resulting mix of positive and negative frequencies depends only on the total (conformal) size of the spacelike regions and not on the detailed form of the metric. Reformulating the problem using junction conditions, we then show that the solutions obtained above are the unique ones which satisfy the natural distributional wave equation everywhere. We also give a variational approach, obtaining the same results from a natural Lagrangian. (PACS numbers 04.20.Cv and 02.40.+m.) |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.