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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1407.0989 | Hal Haggard | Hal M. Haggard and Carlo Rovelli | Black hole fireworks: quantum-gravity effects outside the horizon spark
black to white hole tunneling | 10 pages, 5 figures | Phys. Rev. D 92, 104020 (2015) | 10.1103/PhysRevD.92.104020 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that there is a classical metric satisfying the Einstein equations
outside a finite spacetime region where matter collapses into a black hole and
then emerges from a white hole. We compute this metric explicitly. We show how
quantum theory determines the (long) time for the process to happen. A black
hole can thus quantum-tunnel into a white hole. For this to happen, quantum
gravity should affect the metric also in a small region outside the horizon: we
show that contrary to what is commonly assumed, this is not forbidden by
causality or by the semiclassical approximation, because quantum effects can
pile up over a long time. This scenario alters radically the discussion on the
black hole information puzzle.
| [
{
"created": "Thu, 3 Jul 2014 17:27:45 GMT",
"version": "v1"
},
{
"created": "Sun, 6 Jul 2014 17:46:51 GMT",
"version": "v2"
}
] | 2015-11-11 | [
[
"Haggard",
"Hal M.",
""
],
[
"Rovelli",
"Carlo",
""
]
] | We show that there is a classical metric satisfying the Einstein equations outside a finite spacetime region where matter collapses into a black hole and then emerges from a white hole. We compute this metric explicitly. We show how quantum theory determines the (long) time for the process to happen. A black hole can thus quantum-tunnel into a white hole. For this to happen, quantum gravity should affect the metric also in a small region outside the horizon: we show that contrary to what is commonly assumed, this is not forbidden by causality or by the semiclassical approximation, because quantum effects can pile up over a long time. This scenario alters radically the discussion on the black hole information puzzle. |
gr-qc/9911066 | James Lidsey | James E. Lidsey | Separable Brane Cosmologies in Heterotic M-Theory | 8 pages, plain Latex | Class.Quant.Grav.17:L39-L45,2000 | 10.1088/0264-9381/17/2/103 | null | gr-qc hep-th | null | It is shown that any anisotropic and inhomogeneous cosmological solution to
the lowest-order, four-dimensional, dilaton-graviton string equations of motion
may be employed as a seed to derive a curved, three-brane cosmological solution
to five-dimensional heterotic M-theory compactified on a Calabi-Yau three-fold.
This correspondence formally relates a weakly coupled string cosmology directly
with a strongly coupled one. The asymptotic behaviour of a wide class of
spatially homogeneous braneworlds is deduced. Similar solutions may be derived
in toroidally compactified massive type IIA supergravity.
| [
{
"created": "Thu, 18 Nov 1999 11:39:08 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Lidsey",
"James E.",
""
]
] | It is shown that any anisotropic and inhomogeneous cosmological solution to the lowest-order, four-dimensional, dilaton-graviton string equations of motion may be employed as a seed to derive a curved, three-brane cosmological solution to five-dimensional heterotic M-theory compactified on a Calabi-Yau three-fold. This correspondence formally relates a weakly coupled string cosmology directly with a strongly coupled one. The asymptotic behaviour of a wide class of spatially homogeneous braneworlds is deduced. Similar solutions may be derived in toroidally compactified massive type IIA supergravity. |
1808.06546 | Esteban Gonz\'alez | Felipe Contreras, Norman Cruz, Emilio Elizalde, Esteban Gonz\'alez and
Sergei Odintsov | Linking little rip cosmologies with regular early universes | 18 pages, 17 figures, analysis extended | Phys. Rev. D 98, 123520 (2018) | 10.1103/PhysRevD.98.123520 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Cosmological fluids with a Generalized Equation of State (GEoS) are here
considered, whose corresponding EoS parameter $\omega$ describes a fluid with
phantom behavior, namely $\omega<-1$, but leading to universes free of
singularities at any past or future, finite time. Thus avoiding, in particular,
the Big Bang and the Big Rip singularities, the last one considered to be
typical in phantom fluid models. More specifically, such GEoS fluid cosmologies
lead to regular Little Rip universes. A remarkable new property of these
solutions is proven here, namely that they avoid the initial singularity at
early times; therefore, they are able to describe emergent universes. Solutions
of this kind had been studied previously, but only either as late time or as
early time solutions; never as solutions covering both epochs simultaneously.
Appropriate conditions are proposed here that relate the Little Rip cosmologies
with the initial regular universe, for the future and past regimes,
respectively. This is done by taking as starting point the conditions under
which a given scale factor corresponds to a Little Rip universe.
| [
{
"created": "Mon, 20 Aug 2018 16:20:05 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Dec 2018 20:55:55 GMT",
"version": "v2"
}
] | 2018-12-26 | [
[
"Contreras",
"Felipe",
""
],
[
"Cruz",
"Norman",
""
],
[
"Elizalde",
"Emilio",
""
],
[
"González",
"Esteban",
""
],
[
"Odintsov",
"Sergei",
""
]
] | Cosmological fluids with a Generalized Equation of State (GEoS) are here considered, whose corresponding EoS parameter $\omega$ describes a fluid with phantom behavior, namely $\omega<-1$, but leading to universes free of singularities at any past or future, finite time. Thus avoiding, in particular, the Big Bang and the Big Rip singularities, the last one considered to be typical in phantom fluid models. More specifically, such GEoS fluid cosmologies lead to regular Little Rip universes. A remarkable new property of these solutions is proven here, namely that they avoid the initial singularity at early times; therefore, they are able to describe emergent universes. Solutions of this kind had been studied previously, but only either as late time or as early time solutions; never as solutions covering both epochs simultaneously. Appropriate conditions are proposed here that relate the Little Rip cosmologies with the initial regular universe, for the future and past regimes, respectively. This is done by taking as starting point the conditions under which a given scale factor corresponds to a Little Rip universe. |
gr-qc/0310001 | Richard Price | Zeferino Andrade, Christopher Beetle, Alexey Blinov, Benjamin Bromley,
Lior M. Burko, Maria Cranor, Robert Owen, and Richard H. Price | The Periodic Standing-Wave Approximation: Overview and Three Dimensional
Scalar Models | 13 pages RevTeX, 5 figures. New version. A revised form of the
nonlinearity produces better results | Phys.Rev. D70 (2004) 064001 | 10.1103/PhysRevD.70.064001 | null | gr-qc | null | The periodic standing-wave method for binary inspiral computes the exact
numerical solution for periodic binary motion with standing gravitational
waves, and uses it as an approximation to slow binary inspiral with outgoing
waves. Important features of this method presented here are: (i) the
mathematical nature of the ``mixed'' partial differential equations to be
solved, (ii) the meaning of standing waves in the method, (iii) computational
difficulties, and (iv) the ``effective linearity'' that ultimately justifies
the approximation. The method is applied to three dimensional nonlinear scalar
model problems, and the numerical results are used to demonstrate extraction of
the outgoing solution from the standing-wave solution, and the role of
effective linearity.
| [
{
"created": "Tue, 30 Sep 2003 20:02:12 GMT",
"version": "v1"
},
{
"created": "Sat, 8 May 2004 05:30:26 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Andrade",
"Zeferino",
""
],
[
"Beetle",
"Christopher",
""
],
[
"Blinov",
"Alexey",
""
],
[
"Bromley",
"Benjamin",
""
],
[
"Burko",
"Lior M.",
""
],
[
"Cranor",
"Maria",
""
],
[
"Owen",
"Robert",
""
],
[
"Price",
"Richard H.",
""
]
] | The periodic standing-wave method for binary inspiral computes the exact numerical solution for periodic binary motion with standing gravitational waves, and uses it as an approximation to slow binary inspiral with outgoing waves. Important features of this method presented here are: (i) the mathematical nature of the ``mixed'' partial differential equations to be solved, (ii) the meaning of standing waves in the method, (iii) computational difficulties, and (iv) the ``effective linearity'' that ultimately justifies the approximation. The method is applied to three dimensional nonlinear scalar model problems, and the numerical results are used to demonstrate extraction of the outgoing solution from the standing-wave solution, and the role of effective linearity. |
1708.00156 | Naveen K. Singh Dr. | Abhineet Agarwal, R. Myrzakulov, M. Sami, Naveen K. Singh | Quintessential Inflation in a thawing realization | 11 pages | Phys.Lett. B770 (2017) 200-208 | 10.1016/j.physletb.2017.04.066 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study quintessential inflation with an inverse hyperbolic type potential
$V(\phi) = {V_0}/{\cosh \left( {\phi^n}/{\lambda^n} \right)}$, where $V_0$,
$\lambda$ and "n" are parameters of the theory. We obtain a bound on $\lambda$
for different values of the parameter n. The spectral index and the
tensor-to-scalar-ratio fall in the $1 \sigma$ bound given by the Planck 2015
data for $n \geq 5$ for certain values of $\lambda$. However for $3 \leq n < 5$
there exist values of $\lambda$ for which the spectral index and the
tensor-to-scalar-ratio fall only within the $2 \sigma$ bound of the Planck
data. Furthermore, we show that the scalar field with the given potential can
also give rise to late time acceleration if we invoke the coupling to massive
neutrino matter. We also consider the instant preheating mechanism with Yukawa
interaction and put bounds on the coupling constants for our model using the
nucleosynthesis constraint on relic gravity waves produced during inflation.
| [
{
"created": "Tue, 1 Aug 2017 04:44:38 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Aug 2017 17:03:25 GMT",
"version": "v2"
}
] | 2017-08-04 | [
[
"Agarwal",
"Abhineet",
""
],
[
"Myrzakulov",
"R.",
""
],
[
"Sami",
"M.",
""
],
[
"Singh",
"Naveen K.",
""
]
] | We study quintessential inflation with an inverse hyperbolic type potential $V(\phi) = {V_0}/{\cosh \left( {\phi^n}/{\lambda^n} \right)}$, where $V_0$, $\lambda$ and "n" are parameters of the theory. We obtain a bound on $\lambda$ for different values of the parameter n. The spectral index and the tensor-to-scalar-ratio fall in the $1 \sigma$ bound given by the Planck 2015 data for $n \geq 5$ for certain values of $\lambda$. However for $3 \leq n < 5$ there exist values of $\lambda$ for which the spectral index and the tensor-to-scalar-ratio fall only within the $2 \sigma$ bound of the Planck data. Furthermore, we show that the scalar field with the given potential can also give rise to late time acceleration if we invoke the coupling to massive neutrino matter. We also consider the instant preheating mechanism with Yukawa interaction and put bounds on the coupling constants for our model using the nucleosynthesis constraint on relic gravity waves produced during inflation. |
2008.07327 | Muhammad Sharif | M. Sharif, Iqra Nawazish and Shahid Hussain | Static Wormhole Solutions and Noether Symmetry in Modified Gauss-Bonnet
Gravity | 28 pages, 14 figures, to appear in EPJC | Eur. Phys. J. C 80(2020)783 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we analyze static traversable wormholes via Noether symmetry
technique in modified Gauss-Bonnet $f(\mathcal{G})$ theory of gravity (where
$\mathcal{G}$ represents Gauss-Bonnet term). We assume isotropic matter
configuration and spherically symmetric metric. We construct three
$f(\mathcal{G})$ models, i.e, linear, quadratic and exponential forms and
examine the consistency of these models. The traversable nature of wormhole
solutions is discussed via null energy bound of the effective stress-energy
tensor while physical behavior is studied through standard energy bounds of
isotropic fluid. We also discuss the stability of these wormholes inside the
wormhole throat and conclude the presence of traversable and physically stable
wormholes for quadratic as well as exponential $f(\mathcal{G})$ models.
| [
{
"created": "Fri, 14 Aug 2020 14:32:24 GMT",
"version": "v1"
}
] | 2020-09-03 | [
[
"Sharif",
"M.",
""
],
[
"Nawazish",
"Iqra",
""
],
[
"Hussain",
"Shahid",
""
]
] | In this paper, we analyze static traversable wormholes via Noether symmetry technique in modified Gauss-Bonnet $f(\mathcal{G})$ theory of gravity (where $\mathcal{G}$ represents Gauss-Bonnet term). We assume isotropic matter configuration and spherically symmetric metric. We construct three $f(\mathcal{G})$ models, i.e, linear, quadratic and exponential forms and examine the consistency of these models. The traversable nature of wormhole solutions is discussed via null energy bound of the effective stress-energy tensor while physical behavior is studied through standard energy bounds of isotropic fluid. We also discuss the stability of these wormholes inside the wormhole throat and conclude the presence of traversable and physically stable wormholes for quadratic as well as exponential $f(\mathcal{G})$ models. |
gr-qc/9910048 | Maria Cristina Neacsu | Maria Cristina Neacsu | Dilation Dark Matter in Vaidya-De-Sitter Spacetime | submitt. IJMPD, USA | Int.J.Mod.Phys. D8 (1999) 719-724 | null | null | gr-qc | null | The exterior of a relativistic star can be modelated with the Vaidya
radiating metric. It is started from the generalized Vaidya metric that allows
a type II fluid and studied the conditions of generating new analytical
solutions of the Einstein's field equations. It is shown that the mass
parameter solution gives the classical de Sitter universe in the static case
and the extended de Sitter metric coupled with a dilation scalar field in the
time-dependent case. It is concluded that in the time-dependent case the
atmosphere of a relativistic star consists on an anisotropic string fluid
coupled with a dark matter null fluid and interpreted the scalar field as the
particle that produces the dark matter.
| [
{
"created": "Wed, 13 Oct 1999 14:38:41 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Neacsu",
"Maria Cristina",
""
]
] | The exterior of a relativistic star can be modelated with the Vaidya radiating metric. It is started from the generalized Vaidya metric that allows a type II fluid and studied the conditions of generating new analytical solutions of the Einstein's field equations. It is shown that the mass parameter solution gives the classical de Sitter universe in the static case and the extended de Sitter metric coupled with a dilation scalar field in the time-dependent case. It is concluded that in the time-dependent case the atmosphere of a relativistic star consists on an anisotropic string fluid coupled with a dark matter null fluid and interpreted the scalar field as the particle that produces the dark matter. |
1711.05183 | Alejandro Perez | Alejandro Perez and Daniel Sudarsky | Dark energy from quantum gravity discreteness | Typos corrected, closer to published version | Phys. Rev. Lett. 122, 221302 (2019) | 10.1103/PhysRevLett.122.221302 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We argue that discreteness at the Planck scale (naturally expected to arise
from quantum gravity) might manifest in the form of minute violations of
energy-momentum conservation of the matter degrees of freedom when described in
terms of (idealized) smooth fields on a smooth spacetime. In the context of
applications to cosmology such `energy diffusion' from the low energy matter
degrees of freedom to the discrete structures underlying spacetime leads to the
emergence of an effective dark energy term in Einstein's equations. We estimate
this effect using a (relational) hypothesis about the materialization of
discreteness in quantum gravity which is motivated by the strict observational
constraints supporting the validity of Lorentz invariance at low energies. The
predictions coming from simple dimensional analysis yield a cosmological
constant of the order of magnitude of the observed value without fine tuning.
| [
{
"created": "Tue, 14 Nov 2017 16:44:21 GMT",
"version": "v1"
},
{
"created": "Mon, 11 Dec 2017 16:44:39 GMT",
"version": "v2"
},
{
"created": "Wed, 18 Apr 2018 08:13:28 GMT",
"version": "v3"
},
{
"created": "Mon, 10 Jun 2019 14:27:44 GMT",
"version": "v4"
}
] | 2019-06-12 | [
[
"Perez",
"Alejandro",
""
],
[
"Sudarsky",
"Daniel",
""
]
] | We argue that discreteness at the Planck scale (naturally expected to arise from quantum gravity) might manifest in the form of minute violations of energy-momentum conservation of the matter degrees of freedom when described in terms of (idealized) smooth fields on a smooth spacetime. In the context of applications to cosmology such `energy diffusion' from the low energy matter degrees of freedom to the discrete structures underlying spacetime leads to the emergence of an effective dark energy term in Einstein's equations. We estimate this effect using a (relational) hypothesis about the materialization of discreteness in quantum gravity which is motivated by the strict observational constraints supporting the validity of Lorentz invariance at low energies. The predictions coming from simple dimensional analysis yield a cosmological constant of the order of magnitude of the observed value without fine tuning. |
2006.12272 | Mart\'in G. Richarte MR | Martin G. Richarte and Claudio Simeone | Wormholes in Einstein-Born-Infeld theory | 10 pages, 6 figures. An old article. arXiv admin note: text overlap
with arXiv:1003.0741, arXiv:1001.4034, arXiv:0711.2297 | Phys. Rev. D 81, 109903 (2009) | 10.1103/PhysRevD.81.109903, 10.1103/PhysRevD.80.104033 | null | gr-qc hep-th | http://creativecommons.org/publicdomain/zero/1.0/ | Spherically symmetric thin-shell wormholes are studied within the framework
of Einstein-Born-Infeld theory. We analyze the exotic matter content and find
that for certain values of the Born-Infeld parameter the amount of exotic
matter on the shell can be reduced in relation to the Maxwell case. We also
examine the mechanical stability of the wormhole configurations under radial
perturbations preserving the spherical symmetry.
| [
{
"created": "Thu, 18 Jun 2020 23:37:12 GMT",
"version": "v1"
}
] | 2020-06-23 | [
[
"Richarte",
"Martin G.",
""
],
[
"Simeone",
"Claudio",
""
]
] | Spherically symmetric thin-shell wormholes are studied within the framework of Einstein-Born-Infeld theory. We analyze the exotic matter content and find that for certain values of the Born-Infeld parameter the amount of exotic matter on the shell can be reduced in relation to the Maxwell case. We also examine the mechanical stability of the wormhole configurations under radial perturbations preserving the spherical symmetry. |
1202.4317 | Kazuharu Bamba | Kazuharu Bamba | Equation of State for Dark Energy in Modified Gravity Theories | 7 pages, no figure, contribution to KMI Inauguration Conference
"Quest for the Origin of Particles and the Universe" (KMIIN), 24-26 Nov.
2011, KMI, Nagoya University | null | 10.1142/9789814412322_0008 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore the equation of state (EoS) for dark energy $w_{\mathrm{DE}}$ in
modified gravitational theories to explain the current accelerated expansion of
the universe. We explicitly demonstrate that the future crossings of the
phantom divide line of $w_{\mathrm{DE}}=-1$ are the generic feature in the
existing viable $f(R)$ gravity models. Furthermore, we show that the crossing
of the phantom divide can be realized in the combined $f(T)$ theory constructed
with the exponential and logarithmic terms. In addition, we investigate the
effective EoS for the universe when the finite-time future singularities occur
in non-local gravity.
| [
{
"created": "Mon, 20 Feb 2012 13:23:45 GMT",
"version": "v1"
}
] | 2017-08-23 | [
[
"Bamba",
"Kazuharu",
""
]
] | We explore the equation of state (EoS) for dark energy $w_{\mathrm{DE}}$ in modified gravitational theories to explain the current accelerated expansion of the universe. We explicitly demonstrate that the future crossings of the phantom divide line of $w_{\mathrm{DE}}=-1$ are the generic feature in the existing viable $f(R)$ gravity models. Furthermore, we show that the crossing of the phantom divide can be realized in the combined $f(T)$ theory constructed with the exponential and logarithmic terms. In addition, we investigate the effective EoS for the universe when the finite-time future singularities occur in non-local gravity. |
1810.12767 | Shao-Wen Wei | Hui-Min Wang, Yu-Meng Xu, Shao-Wen Wei | Shadows of Kerr-like black holes in a modified gravity theory | 14 pages, 8 figures | JCAP 1903, 046 (2019) | 10.1088/1475-7516/2019/03/046 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, the shadows cast by non-rotating and rotating modified gravity
black holes are investigated. In addition to the black hole spin parameter $a$
and the inclination angle $\theta$ of observer, another parameter $\alpha$
measuring the deviation of gravitational constant from the Newton one is also
found to affect the shape of the black hole shadow. The result shows that, for
fixed values of $a/M$ and $\theta$, the size and perimeter of the shadows cast
by the non-rotating and rotating black holes significantly increase with the
parameter $\alpha$, while the distortions decrease with $\alpha$. Moreover, the
energy emission rate of the black hole in high energy case is also
investigated, and the result shows that the peak of the emission rate decreases
with the parameter $\alpha$.
| [
{
"created": "Tue, 30 Oct 2018 14:21:02 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Apr 2019 15:55:12 GMT",
"version": "v2"
}
] | 2019-04-08 | [
[
"Wang",
"Hui-Min",
""
],
[
"Xu",
"Yu-Meng",
""
],
[
"Wei",
"Shao-Wen",
""
]
] | In this paper, the shadows cast by non-rotating and rotating modified gravity black holes are investigated. In addition to the black hole spin parameter $a$ and the inclination angle $\theta$ of observer, another parameter $\alpha$ measuring the deviation of gravitational constant from the Newton one is also found to affect the shape of the black hole shadow. The result shows that, for fixed values of $a/M$ and $\theta$, the size and perimeter of the shadows cast by the non-rotating and rotating black holes significantly increase with the parameter $\alpha$, while the distortions decrease with $\alpha$. Moreover, the energy emission rate of the black hole in high energy case is also investigated, and the result shows that the peak of the emission rate decreases with the parameter $\alpha$. |
0811.2029 | Vladimir S. Manko | V.S. Manko, E. Ruiz and J. Sanchez-Mondragon | Analogs of the double-Reissner-Nordstrom solution in magnetostatics and
dilaton gravity: mathematical description and some physical properties | 18 pages, 1 figure; title changed, typos corrected; a considerably
extended version which includes the discussion of the magnetostatic case and
the explicit formula for the magnetic potential | Phys.Rev.D79:084024,2009 | 10.1103/PhysRevD.79.084024 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we consider a magnetic analog of the double-Reissner-Nordstrom
solution and construct the corresponding magnetic potential A_\varphi in the
explicit form. The behavior of the resulting solution under the Harrison
transformation then naturally singles out the asymmetric black diholes -
configurations composed of two non-extreme black holes possessing unequal
masses, and charges equal in magnitude but opposite in sign - as its most
general subclass for which equilibrium of the black-hole constituents can be
achieved with the aid of the external magnetic (or electric) field. We also
generalize the double-Reissner-Nordstrom solution to the dilaton gravity with
arbitrary dilaton coupling, yielding as the result the 4-dimensional
double-Gibbons-Maeda spacetime. The study of some physical properties of the
solutions obtained leads, in particular, to very simple formulas for the areas
of the horizons and surface gravities.
| [
{
"created": "Thu, 13 Nov 2008 04:47:49 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Nov 2008 23:42:57 GMT",
"version": "v2"
},
{
"created": "Sun, 15 Mar 2009 23:45:42 GMT",
"version": "v3"
}
] | 2009-11-06 | [
[
"Manko",
"V. S.",
""
],
[
"Ruiz",
"E.",
""
],
[
"Sanchez-Mondragon",
"J.",
""
]
] | In this paper we consider a magnetic analog of the double-Reissner-Nordstrom solution and construct the corresponding magnetic potential A_\varphi in the explicit form. The behavior of the resulting solution under the Harrison transformation then naturally singles out the asymmetric black diholes - configurations composed of two non-extreme black holes possessing unequal masses, and charges equal in magnitude but opposite in sign - as its most general subclass for which equilibrium of the black-hole constituents can be achieved with the aid of the external magnetic (or electric) field. We also generalize the double-Reissner-Nordstrom solution to the dilaton gravity with arbitrary dilaton coupling, yielding as the result the 4-dimensional double-Gibbons-Maeda spacetime. The study of some physical properties of the solutions obtained leads, in particular, to very simple formulas for the areas of the horizons and surface gravities. |
1012.1991 | Maarten van de Meent | Maarten van de Meent | Piecewise Flat Gravitational Waves | Accepted for publication in Classical and Quantum gravity | Class.Quant.Grav.28:075005,2011 | 10.1088/0264-9381/28/7/075005 | ITP-UU-10/46 SPIN-10/39 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the continuum limit of the piecewise flat locally finite gravity
model introduced by 't Hooft. In the linear weak field limit we find the
energy--momentum tensor and metric perturbation of an arbitrary configuration
of defects. The energy--momentum turns out to be restricted to satisfy certain
conditions. The metric perturbation is mostly fixed by the energy--momentum
except for its lightlike modes which reproduce linear gravitational waves,
despite no such waves being present at the microscopic level.
| [
{
"created": "Thu, 9 Dec 2010 12:54:52 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Feb 2011 09:08:32 GMT",
"version": "v2"
}
] | 2011-03-18 | [
[
"van de Meent",
"Maarten",
""
]
] | We examine the continuum limit of the piecewise flat locally finite gravity model introduced by 't Hooft. In the linear weak field limit we find the energy--momentum tensor and metric perturbation of an arbitrary configuration of defects. The energy--momentum turns out to be restricted to satisfy certain conditions. The metric perturbation is mostly fixed by the energy--momentum except for its lightlike modes which reproduce linear gravitational waves, despite no such waves being present at the microscopic level. |
2210.09307 | Pardyumn Kumar Sahoo | N. S. Kavya, V. Venkatesha, Sanjay Mandal, P.K. Sahoo | Constraining Anisotropic Cosmological Model in
$f(\mathcal{R},\mathscr{L}_m)$ Gravity | Physics of the Dark Universe accepted version | Physics of the Dark Universe 38 (2022) 101126 | 10.1016/j.dark.2022.101126 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The observational evidence regarding the present cosmological aspects tells
us about the presence of very little anisotropy in the universe on a large
scale. Here, in this paper, we attempt to study locally rotationally symmetric
(LRS) homogeneous Bianchi-I spacetime with the isotropic matter distribution.
This is done within the framework of $f(\mathcal{R},\mathscr{L}_m)$ gravity.
Particularly, we consider a non-linear $f(\mathcal{R},\mathscr{L}_m)$ model,
$f(\mathcal{R},\mathscr{L}_m)=\dfrac{1}{2}\mathcal{R}+\mathscr{L}_m^{\,{\alpha}}$.
Furthermore, $\omega$, the equation of state parameter, which is vital stuff in
determining the present phase of the universe is constrained. To constrain the
model parameters and the equation of state parameter, we use 57 Hubble data
points and 1048 Pantheon supernovae type Ia data sample. And, for our
statistical analysis, we use Markoc Chain Monte Carlo (MCMC) simulation.
Moreover, with the help of obtained values of parameters, we measure the
anisotropy parameter for our model.
| [
{
"created": "Mon, 17 Oct 2022 04:52:23 GMT",
"version": "v1"
}
] | 2022-11-02 | [
[
"Kavya",
"N. S.",
""
],
[
"Venkatesha",
"V.",
""
],
[
"Mandal",
"Sanjay",
""
],
[
"Sahoo",
"P. K.",
""
]
] | The observational evidence regarding the present cosmological aspects tells us about the presence of very little anisotropy in the universe on a large scale. Here, in this paper, we attempt to study locally rotationally symmetric (LRS) homogeneous Bianchi-I spacetime with the isotropic matter distribution. This is done within the framework of $f(\mathcal{R},\mathscr{L}_m)$ gravity. Particularly, we consider a non-linear $f(\mathcal{R},\mathscr{L}_m)$ model, $f(\mathcal{R},\mathscr{L}_m)=\dfrac{1}{2}\mathcal{R}+\mathscr{L}_m^{\,{\alpha}}$. Furthermore, $\omega$, the equation of state parameter, which is vital stuff in determining the present phase of the universe is constrained. To constrain the model parameters and the equation of state parameter, we use 57 Hubble data points and 1048 Pantheon supernovae type Ia data sample. And, for our statistical analysis, we use Markoc Chain Monte Carlo (MCMC) simulation. Moreover, with the help of obtained values of parameters, we measure the anisotropy parameter for our model. |
gr-qc/9706004 | Andrew Chamblin | A. Chamblin (Santa Barbara, ITP & Cambridge U., DAMTP), J.M.A.
Ashbourn-Chamblin (Oxford U., Wolfson College), R. Emparan (UC, Santa
Barbara), A. Sornborger (Cambridge U., DAMTP) | Can extreme black holes have (long) Abelian Higgs hair? | 21 pages REVTeX plus 9 figures. Additional figures and mpeg movies
available at http://www.damtp.cam.ac.uk/user/ats25/strhole.html We have made
several cosmetic changes, and we have revised and extended the discussion of
strings which end on extreme horizons | Phys.Rev. D58 (1998) 124014 | 10.1103/PhysRevD.58.124014 | DAMTP R-97/18, UCSBTH-97-10 | gr-qc hep-th | null | It has been argued that a black hole horizon can support the long range
fields of a Nielsen-Olesen string, and that one can think of such a vortex as
black hole ``hair''. In this paper, we examine the properties of an Abelian
Higgs vortex in the presence of a charged black hole as we allow the hole to
approach extremality. Using both analytical and numerical techniques, we show
that the magnetic field lines (as well as the scalar field) of the vortex are
completely expelled from the black hole in the extreme limit. This was to be
expected, since extreme black holes in Einstein-Maxwell theory are known to
exhibit such a ``Meissner effect'' in general. This would seem to imply that a
vortex does not want to be attached to an extreme black hole. We calculate the
total energy of the vortex fields in the presence of an extreme black hole.
When the hole is small relative to the size of the vortex, it is energetically
favoured for the hole to remain inside the vortex region, contrary to the
intuition that the hole should be expelled. However, as we allow the extreme
horizon radius to become very large compared to the radius of the vortex, we do
find evidence of an instability. This proves that it is energetically
unfavourable for a thin vortex to interact with a large extreme black hole.
This would seem to dispel the notion that a black hole can support `long'
abelian Higgs hair in the extreme limit. We show that these considerations do
not go through in the near extreme limit. Finally, we discuss whether this has
implications for strings that end at black holes.
| [
{
"created": "Mon, 2 Jun 1997 19:21:05 GMT",
"version": "v1"
},
{
"created": "Mon, 11 May 1998 21:38:41 GMT",
"version": "v2"
}
] | 2009-10-30 | [
[
"Chamblin",
"A.",
"",
"Santa Barbara, ITP & Cambridge U., DAMTP"
],
[
"Ashbourn-Chamblin",
"J. M. A.",
"",
"Oxford U., Wolfson College"
],
[
"Emparan",
"R.",
"",
"UC, Santa\n Barbara"
],
[
"Sornborger",
"A.",
"",
"Cambridge U., DAMTP"
]
] | It has been argued that a black hole horizon can support the long range fields of a Nielsen-Olesen string, and that one can think of such a vortex as black hole ``hair''. In this paper, we examine the properties of an Abelian Higgs vortex in the presence of a charged black hole as we allow the hole to approach extremality. Using both analytical and numerical techniques, we show that the magnetic field lines (as well as the scalar field) of the vortex are completely expelled from the black hole in the extreme limit. This was to be expected, since extreme black holes in Einstein-Maxwell theory are known to exhibit such a ``Meissner effect'' in general. This would seem to imply that a vortex does not want to be attached to an extreme black hole. We calculate the total energy of the vortex fields in the presence of an extreme black hole. When the hole is small relative to the size of the vortex, it is energetically favoured for the hole to remain inside the vortex region, contrary to the intuition that the hole should be expelled. However, as we allow the extreme horizon radius to become very large compared to the radius of the vortex, we do find evidence of an instability. This proves that it is energetically unfavourable for a thin vortex to interact with a large extreme black hole. This would seem to dispel the notion that a black hole can support `long' abelian Higgs hair in the extreme limit. We show that these considerations do not go through in the near extreme limit. Finally, we discuss whether this has implications for strings that end at black holes. |
2404.04978 | Zhu Yi | Jie Liu, Yungui Gong, Zhu Yi | Constant-roll inflation with non-minimally derivative coupling | 8 pages, accepted by Communications in Theoretical Physics | Commun. Theor. Phys. 76 (2024) 095401 | 10.1088/1572-9494/ad51ef | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the constant-roll inflation with non-minimally kinetic
coupling to the Einstein tensor. With the slow-roll parameter $\eta_\phi =
-\ddot{\phi}/(H\dot{\phi})$ being a constant, we calculate the power spectra
for scalar and tensor perturbations, and derive the expressions for the scalar
spectral tilt $n_s$, the tensor spectral tilt $n_T$, and the tensor-to-scalar
ratio $r$. We find that the expressions for $n_s$ are different with different
ordering of taking the derivative of the scalar power spectrum with respect to
the scale $k$ and the horizon crossing condition $c_sk=aH$ in the constant-roll
inflation, the consistency relation $r=-8n_T$ does not hold if $|\eta_\phi|$ is
not small, and the duality of the tensor-to-scalar ratio between the slow-roll
inflation and ultra-slow-roll inflation does not exist in inflationary models
with non-minimally derivative coupling. The result offers a fresh perspective
on the understanding of the inflationary models with non-minimally derivative
coupling and is helpful for the production of scalar induced gravitational
waves in the framework of ultra-slow-roll inflation with non-minimally
derivative coupling.
| [
{
"created": "Sun, 7 Apr 2024 14:39:37 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Jun 2024 08:48:04 GMT",
"version": "v2"
}
] | 2024-07-22 | [
[
"Liu",
"Jie",
""
],
[
"Gong",
"Yungui",
""
],
[
"Yi",
"Zhu",
""
]
] | We investigate the constant-roll inflation with non-minimally kinetic coupling to the Einstein tensor. With the slow-roll parameter $\eta_\phi = -\ddot{\phi}/(H\dot{\phi})$ being a constant, we calculate the power spectra for scalar and tensor perturbations, and derive the expressions for the scalar spectral tilt $n_s$, the tensor spectral tilt $n_T$, and the tensor-to-scalar ratio $r$. We find that the expressions for $n_s$ are different with different ordering of taking the derivative of the scalar power spectrum with respect to the scale $k$ and the horizon crossing condition $c_sk=aH$ in the constant-roll inflation, the consistency relation $r=-8n_T$ does not hold if $|\eta_\phi|$ is not small, and the duality of the tensor-to-scalar ratio between the slow-roll inflation and ultra-slow-roll inflation does not exist in inflationary models with non-minimally derivative coupling. The result offers a fresh perspective on the understanding of the inflationary models with non-minimally derivative coupling and is helpful for the production of scalar induced gravitational waves in the framework of ultra-slow-roll inflation with non-minimally derivative coupling. |
2103.10802 | Hayato Motohashi | Hayato Motohashi, Sousuke Noda | Exact solution for wave scattering from black holes: Formulation | 22 pages, 6 figures; matches published version | Prog. Theor. Exp. Phys. 2021, 083E03 (2021) | 10.1093/ptep/ptab097 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We establish an exact formulation for wave scattering of a massless field
with spin and charge by a Kerr-Newman-de Sitter black hole. Our formulation is
based on the exact solution of the Teukolsky equation in terms of the local
Heun function, and does not require any approximation. It serves as simple
exact formulae with arbitrary high precision, which realize fast calculation
without restrictions on model parameters. We highlight several applications
including quasinormal modes, cross section, reflection/absorption rate, and
Green function.
| [
{
"created": "Fri, 19 Mar 2021 13:40:48 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Aug 2021 00:25:51 GMT",
"version": "v2"
}
] | 2021-08-31 | [
[
"Motohashi",
"Hayato",
""
],
[
"Noda",
"Sousuke",
""
]
] | We establish an exact formulation for wave scattering of a massless field with spin and charge by a Kerr-Newman-de Sitter black hole. Our formulation is based on the exact solution of the Teukolsky equation in terms of the local Heun function, and does not require any approximation. It serves as simple exact formulae with arbitrary high precision, which realize fast calculation without restrictions on model parameters. We highlight several applications including quasinormal modes, cross section, reflection/absorption rate, and Green function. |
2210.03010 | Sen Guo | Sen Guo, Guan-Ru Li, En-Wei Liang | Optical appearance of a thin-shell wormhole with a Hayward profile | 12 pages, 8 figures | published EPJC (2023) | 10.1140/epjc/s10052-023-11842-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The optical properties of a thin-shell wormhole (TSW) with a Hayward profile
is investigated. Adopting the ray-tracing method, we demonstrate that the TSW's
contralateral spacetime is capable of reflecting a significant portion of light
back to the observer spacetime. We analyze the effective potential, light
deflection, and azimuthal angle of the TSW and find that these quantities are
affected by the mass ratio of the black holes (BHs). Specifically, if the mass
of the contralateral spacetime BH is greater than that of the original
spacetime BH, and the impact parameter satisfies the condition $Hb_{\rm
c2}<b_{1}<b_{\rm c1}$, the trajectory of the photon exhibits round-trip
characteristics. Assuming the presence of a thin accretion disk surrounding the
observing spacetime BH, our results indicate that the image formed by the TSW
exhibits additional photon rings and a lensing band compared to an image
produced by a BH alone.
| [
{
"created": "Thu, 6 Oct 2022 15:58:16 GMT",
"version": "v1"
},
{
"created": "Sun, 1 Jan 2023 15:52:20 GMT",
"version": "v2"
},
{
"created": "Sat, 8 Apr 2023 08:35:06 GMT",
"version": "v3"
},
{
"created": "Tue, 9 May 2023 05:08:57 GMT",
"version": "v4"
},
{
"created": "Mon, 17 Jul 2023 08:55:58 GMT",
"version": "v5"
}
] | 2023-08-09 | [
[
"Guo",
"Sen",
""
],
[
"Li",
"Guan-Ru",
""
],
[
"Liang",
"En-Wei",
""
]
] | The optical properties of a thin-shell wormhole (TSW) with a Hayward profile is investigated. Adopting the ray-tracing method, we demonstrate that the TSW's contralateral spacetime is capable of reflecting a significant portion of light back to the observer spacetime. We analyze the effective potential, light deflection, and azimuthal angle of the TSW and find that these quantities are affected by the mass ratio of the black holes (BHs). Specifically, if the mass of the contralateral spacetime BH is greater than that of the original spacetime BH, and the impact parameter satisfies the condition $Hb_{\rm c2}<b_{1}<b_{\rm c1}$, the trajectory of the photon exhibits round-trip characteristics. Assuming the presence of a thin accretion disk surrounding the observing spacetime BH, our results indicate that the image formed by the TSW exhibits additional photon rings and a lensing band compared to an image produced by a BH alone. |
2401.05181 | Naveena Kumara A | A. Naveena Kumara, Shreyas Punacha and Md Sabir Ali | Lyapunov Exponents and Phase Structure of Lifshitz and Hyperscaling
Violating Black Holes | 35 pages, 10 figures. Revised version | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We study the phase structure of hyperscaling violating black holes using
Lyapunov exponents. For describing hyperscaling violating system, we chose a
particular gravity model constructed from generalized Einstein-Maxwell-Dilaton
action which includes the Lifshitz cases in appropriate limit. We study the
relationship between Lyapunov exponents and black hole phase transitions
considering both the timelike and null geodesics. We observe that, the black
hole phase transiton properties are reflected in Lyapunov exponent where its
multiple branches correspond to the distinct phases of the black hole. The
discontinuos change of the Lyapunov exponent during the phase transition serve
as an order parameter with critical exponent $1/2$ near the critical point. Our
numerical study reveals that the correlation between the Lyapunov exponent and
black hole thermodynamic properties can be generalised beyond the AdS
spacetime. We find that it is independent of the hyperscaling violation
parameter as well as the Lifshitz exponent.
| [
{
"created": "Wed, 10 Jan 2024 14:32:17 GMT",
"version": "v1"
},
{
"created": "Sat, 2 Mar 2024 17:37:46 GMT",
"version": "v2"
}
] | 2024-03-05 | [
[
"Kumara",
"A. Naveena",
""
],
[
"Punacha",
"Shreyas",
""
],
[
"Ali",
"Md Sabir",
""
]
] | We study the phase structure of hyperscaling violating black holes using Lyapunov exponents. For describing hyperscaling violating system, we chose a particular gravity model constructed from generalized Einstein-Maxwell-Dilaton action which includes the Lifshitz cases in appropriate limit. We study the relationship between Lyapunov exponents and black hole phase transitions considering both the timelike and null geodesics. We observe that, the black hole phase transiton properties are reflected in Lyapunov exponent where its multiple branches correspond to the distinct phases of the black hole. The discontinuos change of the Lyapunov exponent during the phase transition serve as an order parameter with critical exponent $1/2$ near the critical point. Our numerical study reveals that the correlation between the Lyapunov exponent and black hole thermodynamic properties can be generalised beyond the AdS spacetime. We find that it is independent of the hyperscaling violation parameter as well as the Lifshitz exponent. |
1403.1725 | Adam Chudecki Dr | Adam Chudecki, Michal Dobrski | Proper conformal symmetries in SD Einstein spaces | null | Journal of Mathematical Physics, 55, 082502 (2014) | 10.1063/1.4893000 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Proper conformal symmetries in self-dual (SD) Einstein spaces are considered.
It is shown, that such symmetries are admitted only by the Einstein spaces of
the type [N]x[N]. Spaces of the type [N]x[-] are considered in details.
Existence of the proper conformal Killing vector implies existence of the
isometric, covariantly constant and null Killing vector. It is shown, that
there are two classes of [N]x[-]-metrics admitting proper conformal symmetry.
They can be distinguished by analysis of the associated anti-self-dual (ASD)
null strings. Both classes are analyzed in details. The problem is reduced to
single linear PDE. Some general and special solutions of this PDE are
presented.
| [
{
"created": "Fri, 7 Mar 2014 11:36:57 GMT",
"version": "v1"
}
] | 2014-10-29 | [
[
"Chudecki",
"Adam",
""
],
[
"Dobrski",
"Michal",
""
]
] | Proper conformal symmetries in self-dual (SD) Einstein spaces are considered. It is shown, that such symmetries are admitted only by the Einstein spaces of the type [N]x[N]. Spaces of the type [N]x[-] are considered in details. Existence of the proper conformal Killing vector implies existence of the isometric, covariantly constant and null Killing vector. It is shown, that there are two classes of [N]x[-]-metrics admitting proper conformal symmetry. They can be distinguished by analysis of the associated anti-self-dual (ASD) null strings. Both classes are analyzed in details. The problem is reduced to single linear PDE. Some general and special solutions of this PDE are presented. |
1203.2641 | Olaf Dreyer | Olaf Dreyer | Internal Relativity | 9 pages, RevTex4 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | General relativity differs from other forces in nature in that it can be made
to disappear locally. This is the essence of the equivalence principle. In
general relativity the equivalence principle is implemented using differential
geometry. The connection that comes from a metric is used to glue together the
different gravity-free Minkowski spaces. In this article we argue that there is
another way to implement the equivalence principle. In this new way it is not
different Minkowski spaces that are connected but different vacua of an
underlying solid-state like model. One advantage of this approach to gravity is
that one can start with a quantum mechanical model so that the question of how
to arrive at a quantum theory of gravity does not arise. We show how the
gravitational constant can be calculated in this setup.
| [
{
"created": "Mon, 12 Mar 2012 20:41:26 GMT",
"version": "v1"
}
] | 2012-03-14 | [
[
"Dreyer",
"Olaf",
""
]
] | General relativity differs from other forces in nature in that it can be made to disappear locally. This is the essence of the equivalence principle. In general relativity the equivalence principle is implemented using differential geometry. The connection that comes from a metric is used to glue together the different gravity-free Minkowski spaces. In this article we argue that there is another way to implement the equivalence principle. In this new way it is not different Minkowski spaces that are connected but different vacua of an underlying solid-state like model. One advantage of this approach to gravity is that one can start with a quantum mechanical model so that the question of how to arrive at a quantum theory of gravity does not arise. We show how the gravitational constant can be calculated in this setup. |
1611.01508 | Ilya Vilensky | Ilya Vilensky | Spinfoam cosmology with the proper vertex amplitude | improved presentation, added references, included discussion of
long-range correlations | Class. Quantum Grav. 34 225015 (2017) | 10.1088/1361-6382/aa91f4 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The proper vertex amplitude is derived from the EPRL vertex by restricting to
a single gravitational sector in order to achieve the correct semi-classical
behaviour. We apply the proper vertex to calculate a cosmological transition
amplitude that can be viewed as the Hartle-Hawking wavefunction. To perform
this calculation we deduce the integral form of the proper vertex and use
extended stationary phase methods to estimate the large-volume limit. We show
that the resulting amplitude satisfies an operator constraint whose classical
analogue is the Hamiltonian constraint of the Friedmann-Robertson-Walker
cosmology. We find that the constraint dynamically selects the relevant family
of coherent states and demonstrate a similar dynamic selection in standard
quantum mechanics. We investigate the effects of dynamical selection on
long-range correlations.
| [
{
"created": "Fri, 4 Nov 2016 19:55:51 GMT",
"version": "v1"
},
{
"created": "Wed, 29 Mar 2017 20:26:29 GMT",
"version": "v2"
}
] | 2018-05-29 | [
[
"Vilensky",
"Ilya",
""
]
] | The proper vertex amplitude is derived from the EPRL vertex by restricting to a single gravitational sector in order to achieve the correct semi-classical behaviour. We apply the proper vertex to calculate a cosmological transition amplitude that can be viewed as the Hartle-Hawking wavefunction. To perform this calculation we deduce the integral form of the proper vertex and use extended stationary phase methods to estimate the large-volume limit. We show that the resulting amplitude satisfies an operator constraint whose classical analogue is the Hamiltonian constraint of the Friedmann-Robertson-Walker cosmology. We find that the constraint dynamically selects the relevant family of coherent states and demonstrate a similar dynamic selection in standard quantum mechanics. We investigate the effects of dynamical selection on long-range correlations. |
0805.4302 | Amit Ghosh | A. Ghosh and P. Mitra | A comment on black hole state counting in loop quantum gravity | 1 page | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | There are two ways of counting microscopic states of black holes in loop
quantum gravity, one counting all allowed spin network labels $j,m$ and the
other involving only the labels $m$. Counting states with $|m|=j$, as done in a
recent Letter, does not follow either.
| [
{
"created": "Wed, 28 May 2008 10:22:10 GMT",
"version": "v1"
}
] | 2008-05-29 | [
[
"Ghosh",
"A.",
""
],
[
"Mitra",
"P.",
""
]
] | There are two ways of counting microscopic states of black holes in loop quantum gravity, one counting all allowed spin network labels $j,m$ and the other involving only the labels $m$. Counting states with $|m|=j$, as done in a recent Letter, does not follow either. |
2007.13799 | Shammi Tahura | Shammi Tahura, David A. Nichols, Alexander Saffer, Leo C. Stein, Kent
Yagi | Brans-Dicke theory in Bondi-Sachs form: Asymptotically flat solutions,
asymptotic symmetries and gravitational-wave memory effects | Appendix added, section 2B modified, minor modifications to the
introduction, matches published version | Phys. Rev. D 103, 104026 (2021) | 10.1103/PhysRevD.103.104026 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational-wave memory effects are identified by their distinctive effects
on families of freely falling observers: after a burst of waves pass by their
locations, memory effects can cause lasting relative displacements of the
observers. These effects are closely related to the infrared properties of
gravity and other massless field theories, including their asymptotic
symmetries and conserved quantities. In this paper, we investigate the
connection between memory effects, symmetries, and conserved quantities in
Brans-Dicke theory. We compute the field equations in Bondi coordinates, and we
define a set of boundary conditions that represent asymptotically flat
solutions in this context. Next, we derive the asymptotic symmetry group of
these spacetimes, and we find that it is the same as the Bondi-Metzner-Sachs
group in general relativity. Because there is an additional polarization of
gravitational waves in Brans-Dicke theory, we compute the memory effects
associated with this extra polarization (the so-called "breathing" mode). This
breathing mode produces a uniform expansion (or contraction) of a ring of
freely falling observers. After these breathing gravitational waves pass by the
observers' locations, there are two additional memory effects that depend on
their initial displacements and relative velocities. Neither of these
additional memory effects seems to be related to asymptotic symmetries or
conserved quantities; rather, they are determined by the properties of the
nonradiative region before and after the bursts of the scalar field and the
gravitational waves. We discuss the properties of these regions necessary to
support nontrivial breathing-mode-type memory effects.
| [
{
"created": "Mon, 27 Jul 2020 18:28:49 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Jul 2021 18:32:13 GMT",
"version": "v2"
}
] | 2021-07-07 | [
[
"Tahura",
"Shammi",
""
],
[
"Nichols",
"David A.",
""
],
[
"Saffer",
"Alexander",
""
],
[
"Stein",
"Leo C.",
""
],
[
"Yagi",
"Kent",
""
]
] | Gravitational-wave memory effects are identified by their distinctive effects on families of freely falling observers: after a burst of waves pass by their locations, memory effects can cause lasting relative displacements of the observers. These effects are closely related to the infrared properties of gravity and other massless field theories, including their asymptotic symmetries and conserved quantities. In this paper, we investigate the connection between memory effects, symmetries, and conserved quantities in Brans-Dicke theory. We compute the field equations in Bondi coordinates, and we define a set of boundary conditions that represent asymptotically flat solutions in this context. Next, we derive the asymptotic symmetry group of these spacetimes, and we find that it is the same as the Bondi-Metzner-Sachs group in general relativity. Because there is an additional polarization of gravitational waves in Brans-Dicke theory, we compute the memory effects associated with this extra polarization (the so-called "breathing" mode). This breathing mode produces a uniform expansion (or contraction) of a ring of freely falling observers. After these breathing gravitational waves pass by the observers' locations, there are two additional memory effects that depend on their initial displacements and relative velocities. Neither of these additional memory effects seems to be related to asymptotic symmetries or conserved quantities; rather, they are determined by the properties of the nonradiative region before and after the bursts of the scalar field and the gravitational waves. We discuss the properties of these regions necessary to support nontrivial breathing-mode-type memory effects. |
1704.05506 | Orr Sela | Assaf Lanir, Amos Ori and Orr Sela | Curing the Self-Force Runaway Problem in Finite-Difference Integration | 12 pages, 7 figures; A significant extension of this manuscript was
published in PRD by A. Lanir and O. Sela | Phys. Rev. D 99, 064031 (2019) | 10.1103/PhysRevD.99.064031 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The electromagnetic self-force equation of motion is known to be afflicted by
the so-called runaway problem. A similar problem arises in the semiclassical
Einstein's field equation and plagues the self-consistent semiclassical
evolution of spacetime. Motivated to overcome the latter challenge, we first
address the former (which is conceptually simpler), and present a pragmatic
finite-difference method designed to numerically integrate the self-force
equation of motion while curing the runaway problem. We restrict our attention
here to a charged point-like mass in a one-dimensional motion, under a
prescribed time-dependent external force $F_{ext}(t)$. We demonstrate the
implementation of our method using two different examples of external force: a
Gaussian and a Sin^4 function. In each of these examples we compare our
numerical results with those obtained by two other methods (a Dirac-type
solution and a reduction-of-order solution). Both external-force examples
demonstrate a complete suppression of the undesired runaway mode, along with an
accurate account of the radiation-reaction effect at the physically relevant
time scale, thereby illustrating the effectiveness of our method in curing the
self-force runaway problem.
| [
{
"created": "Tue, 18 Apr 2017 20:03:49 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Apr 2019 13:18:35 GMT",
"version": "v2"
}
] | 2019-04-03 | [
[
"Lanir",
"Assaf",
""
],
[
"Ori",
"Amos",
""
],
[
"Sela",
"Orr",
""
]
] | The electromagnetic self-force equation of motion is known to be afflicted by the so-called runaway problem. A similar problem arises in the semiclassical Einstein's field equation and plagues the self-consistent semiclassical evolution of spacetime. Motivated to overcome the latter challenge, we first address the former (which is conceptually simpler), and present a pragmatic finite-difference method designed to numerically integrate the self-force equation of motion while curing the runaway problem. We restrict our attention here to a charged point-like mass in a one-dimensional motion, under a prescribed time-dependent external force $F_{ext}(t)$. We demonstrate the implementation of our method using two different examples of external force: a Gaussian and a Sin^4 function. In each of these examples we compare our numerical results with those obtained by two other methods (a Dirac-type solution and a reduction-of-order solution). Both external-force examples demonstrate a complete suppression of the undesired runaway mode, along with an accurate account of the radiation-reaction effect at the physically relevant time scale, thereby illustrating the effectiveness of our method in curing the self-force runaway problem. |
1909.00284 | Erik Lentz | Erik W. Lentz | Exotic Behaviors of Space-time in Einstein-Maxwell Theory | 6 pages, 6 figures | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper examines the structure of electric fields and space-times created
by extended finite distributions of irrotational static and
spherically-symmetric charge. The resulting electric fields are found to source
features in space-time commonly associated with the presence of fields with
locally positive and negative mass densities, with the sign of the mass
corresponding to the sign of the electric field gradient. The conditions
detailing these behaviors are discussed. The effects of these structures on
trajectories of time-like geodesics and the volume form are also presented.
| [
{
"created": "Sat, 31 Aug 2019 20:46:35 GMT",
"version": "v1"
}
] | 2019-09-04 | [
[
"Lentz",
"Erik W.",
""
]
] | This paper examines the structure of electric fields and space-times created by extended finite distributions of irrotational static and spherically-symmetric charge. The resulting electric fields are found to source features in space-time commonly associated with the presence of fields with locally positive and negative mass densities, with the sign of the mass corresponding to the sign of the electric field gradient. The conditions detailing these behaviors are discussed. The effects of these structures on trajectories of time-like geodesics and the volume form are also presented. |
2207.12745 | Puxun Wu | Rongrong Zhai, Hongwei Yu and Puxun Wu | Growth of power spectrum due to decrease of sound speed during inflation | 11 pages, 1 figure. three references added | Physical Review D 106, 023517 (2022) | 10.1103/PhysRevD.106.023517 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study the amplification of the curvature perturbations due to a small
sound speed and find that its origin is different completely from that due to
the ultraslow-roll inflation. This is because when the sound speed is very
small the enhancement of the power spectrum comes from the fact that the
curvature perturbations at the scales smaller than the cosmic microwave
background (CMB) scale becomes scale-variant, rather than growing that leads to
the amplification of the curvature perturbations during the ultraslow-roll
inflation. At large scales the power spectrum of the curvature perturbations
remains to be scale invariant, which is consistent with the CMB observations,
and then it will have a transient $k^2$ growth and finally approach a $k^4$
growth as the scale becomes smaller and smaller. Thus the power spectrum can be
enhanced to generate a sizable amount of primordial black holes. Furthermore,
when the high order correction in the dispersion relation of the curvature
perturbations is considered the growth of the power spectrum of the curvature
perturbations has the same origin as that in the case without this correction.
| [
{
"created": "Tue, 26 Jul 2022 08:51:54 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Sep 2022 12:13:38 GMT",
"version": "v2"
}
] | 2022-09-20 | [
[
"Zhai",
"Rongrong",
""
],
[
"Yu",
"Hongwei",
""
],
[
"Wu",
"Puxun",
""
]
] | We study the amplification of the curvature perturbations due to a small sound speed and find that its origin is different completely from that due to the ultraslow-roll inflation. This is because when the sound speed is very small the enhancement of the power spectrum comes from the fact that the curvature perturbations at the scales smaller than the cosmic microwave background (CMB) scale becomes scale-variant, rather than growing that leads to the amplification of the curvature perturbations during the ultraslow-roll inflation. At large scales the power spectrum of the curvature perturbations remains to be scale invariant, which is consistent with the CMB observations, and then it will have a transient $k^2$ growth and finally approach a $k^4$ growth as the scale becomes smaller and smaller. Thus the power spectrum can be enhanced to generate a sizable amount of primordial black holes. Furthermore, when the high order correction in the dispersion relation of the curvature perturbations is considered the growth of the power spectrum of the curvature perturbations has the same origin as that in the case without this correction. |
gr-qc/0107094 | Felix Finster | Felix Finster, Niky Kamran, Joel Smoller, and Shing-Tung Yau | Decay Rates and Probability Estimates for Massive Dirac Particles in the
Kerr-Newman Black Hole Geometry | 42 pages, 3 figures (published version) | Commun.Math.Phys. 230 (2002) 201-244 | 10.1007/s002200200648 | null | gr-qc math-ph math.AP math.MP | null | The Cauchy problem is considered for the massive Dirac equation in the
non-extreme Kerr-Newman geometry, for smooth initial data with compact support
outside the event horizon and bounded angular momentum. We prove that the Dirac
wave function decays in L^\infty_loc at least at the rate t^{-5/6}. For generic
initial data, this rate of decay is sharp. We derive a formula for the
probability p that the Dirac particle escapes to infinity. For various
conditions on the initial data, we show that p=0,1 or 0<p<1. The proofs are
based on a refined analysis of the Dirac propagator constructed in
gr-qc/0005088.
| [
{
"created": "Sat, 28 Jul 2001 19:34:37 GMT",
"version": "v1"
},
{
"created": "Thu, 31 Jan 2002 10:10:02 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Finster",
"Felix",
""
],
[
"Kamran",
"Niky",
""
],
[
"Smoller",
"Joel",
""
],
[
"Yau",
"Shing-Tung",
""
]
] | The Cauchy problem is considered for the massive Dirac equation in the non-extreme Kerr-Newman geometry, for smooth initial data with compact support outside the event horizon and bounded angular momentum. We prove that the Dirac wave function decays in L^\infty_loc at least at the rate t^{-5/6}. For generic initial data, this rate of decay is sharp. We derive a formula for the probability p that the Dirac particle escapes to infinity. For various conditions on the initial data, we show that p=0,1 or 0<p<1. The proofs are based on a refined analysis of the Dirac propagator constructed in gr-qc/0005088. |
1607.07963 | Seramika Ariwahjoedi | Seramika Ariwahjoedi, Jusak Sali Kosasih, Carlo Rovelli, Freddy P. Zen | Degrees of freedom in discrete geometry | 20 pages, 21 figures. The information contained in this article was
extracted from a doctoral thesis by the author | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Following recent developments in discrete gravity, we study geometrical
variables (angles and forms) of simplices in the discrete geometry point of
view. Some of our relatively new results include: new ways of writing a set of
simplices using vectorial (differential form) and coordinate-free pictures, and
a consistent procedure to couple particles of space, together with a method to
calculate the degrees of freedom of the system of 'quanta' of space in the
classical framework.
| [
{
"created": "Wed, 27 Jul 2016 05:16:37 GMT",
"version": "v1"
},
{
"created": "Sun, 18 Sep 2016 08:55:38 GMT",
"version": "v2"
}
] | 2016-09-20 | [
[
"Ariwahjoedi",
"Seramika",
""
],
[
"Kosasih",
"Jusak Sali",
""
],
[
"Rovelli",
"Carlo",
""
],
[
"Zen",
"Freddy P.",
""
]
] | Following recent developments in discrete gravity, we study geometrical variables (angles and forms) of simplices in the discrete geometry point of view. Some of our relatively new results include: new ways of writing a set of simplices using vectorial (differential form) and coordinate-free pictures, and a consistent procedure to couple particles of space, together with a method to calculate the degrees of freedom of the system of 'quanta' of space in the classical framework. |
gr-qc/0404052 | Jorge Pullin | Cayetano Di Bartolo, Rodolfo Gambini, Jorge Pullin | Consistent and mimetic discretizations in general relativity | 14 pages, Revtex, no figures, final version to appear in JMP | J.Math.Phys. 46 (2005) 032501 | 10.1063/1.1841483 | LSU-REL-041204 | gr-qc | null | A discretization of a continuum theory with constraints or conserved
quantities is called mimetic if it mirrors the conserved laws or constraints of
the continuum theory at the discrete level. Such discretizations have been
found useful in continuum mechanics and in electromagnetism. We have recently
introduced a new technique for discretizing constrained theories. The technique
yields discretizations that are consistent, in the sense that the constraints
and evolution equations can be solved simultaneously, but it cannot be
considered mimetic since it achieves consistency by determining the Lagrange
multipliers. In this paper we would like to show that when applied to general
relativity linearized around a Minkowski background the technique yields a
discretization that is mimetic in the traditional sense of the word. We show
this using the traditional metric variables and also the Ashtekar new
variables, but in the latter case we restrict ourselves to the Euclidean case.
We also argue that there appear to exist conceptual difficulties to the
construction of a mimetic formulation of the full Einstein equations, and
suggest that the new discretization scheme can provide an alternative that is
nevertheless close in spirit to the traditional mimetic formulations.
| [
{
"created": "Mon, 12 Apr 2004 20:46:44 GMT",
"version": "v1"
},
{
"created": "Sun, 30 May 2004 17:39:19 GMT",
"version": "v2"
},
{
"created": "Tue, 1 Jun 2004 03:08:43 GMT",
"version": "v3"
},
{
"created": "Mon, 1 Nov 2004 21:41:02 GMT",
"version": "v4"
}
] | 2007-05-23 | [
[
"Di Bartolo",
"Cayetano",
""
],
[
"Gambini",
"Rodolfo",
""
],
[
"Pullin",
"Jorge",
""
]
] | A discretization of a continuum theory with constraints or conserved quantities is called mimetic if it mirrors the conserved laws or constraints of the continuum theory at the discrete level. Such discretizations have been found useful in continuum mechanics and in electromagnetism. We have recently introduced a new technique for discretizing constrained theories. The technique yields discretizations that are consistent, in the sense that the constraints and evolution equations can be solved simultaneously, but it cannot be considered mimetic since it achieves consistency by determining the Lagrange multipliers. In this paper we would like to show that when applied to general relativity linearized around a Minkowski background the technique yields a discretization that is mimetic in the traditional sense of the word. We show this using the traditional metric variables and also the Ashtekar new variables, but in the latter case we restrict ourselves to the Euclidean case. We also argue that there appear to exist conceptual difficulties to the construction of a mimetic formulation of the full Einstein equations, and suggest that the new discretization scheme can provide an alternative that is nevertheless close in spirit to the traditional mimetic formulations. |
2407.00283 | Yu-Xiao Liu | Sen Yang, Yu-Peng Zhang, Tao Zhu, Li Zhao, and Yu-Xiao Liu | Gravitational waveforms from periodic orbits around a quantum-corrected
black hole | 16 pages, 12 figures, and 2 tables | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Extreme mass-ratio inspirals are crucial sources for future space-based
gravitational wave detections. Gravitational waveforms emitted by extreme
mass-ratio inspirals are closely related to the orbital dynamics of small
celestial objects, which vary with the underlying spacetime geometry. Despite
the tremendous success of general relativity, there are unsolved issues such as
singularities in both black holes and cosmology. Loop quantum gravity, a theory
addressing these singularity problems, offers a framework for regular black
holes. In this paper, we focus on periodic orbits of a small celestial object
around a supermassive quantum-corrected black hole in loop quantum gravity and
compute the corresponding gravitational waveforms. We view the small celestial
object as a massive test particle and obtain its four-velocity and effective
potential. Our results indicate that the quantum parameter $\hat{\alpha}$
influences the shape of the effective potential. We explore the effects of
quantum corrections on marginally bound orbits, innermost stable circular
orbits, and other periodic orbits. Using the numerical kludge scheme, we
further explore the gravitational waveforms of the small celestial object along
different periodic orbits. The waveforms exhibit distinct zoom and whirl phases
in a complete orbital period, closely tied to the quantum parameter
$\hat{\alpha}$. We also perform a spectral analysis of the gravitational waves
from these periodic orbits and assess their detectability. With the steady
progress of space-based gravitational wave detection programs, our findings
will contribute to utilizing extreme mass-ratio inspirals to test and
understand the properties of quantum-corrected black holes.
| [
{
"created": "Sat, 29 Jun 2024 02:25:32 GMT",
"version": "v1"
}
] | 2024-07-02 | [
[
"Yang",
"Sen",
""
],
[
"Zhang",
"Yu-Peng",
""
],
[
"Zhu",
"Tao",
""
],
[
"Zhao",
"Li",
""
],
[
"Liu",
"Yu-Xiao",
""
]
] | Extreme mass-ratio inspirals are crucial sources for future space-based gravitational wave detections. Gravitational waveforms emitted by extreme mass-ratio inspirals are closely related to the orbital dynamics of small celestial objects, which vary with the underlying spacetime geometry. Despite the tremendous success of general relativity, there are unsolved issues such as singularities in both black holes and cosmology. Loop quantum gravity, a theory addressing these singularity problems, offers a framework for regular black holes. In this paper, we focus on periodic orbits of a small celestial object around a supermassive quantum-corrected black hole in loop quantum gravity and compute the corresponding gravitational waveforms. We view the small celestial object as a massive test particle and obtain its four-velocity and effective potential. Our results indicate that the quantum parameter $\hat{\alpha}$ influences the shape of the effective potential. We explore the effects of quantum corrections on marginally bound orbits, innermost stable circular orbits, and other periodic orbits. Using the numerical kludge scheme, we further explore the gravitational waveforms of the small celestial object along different periodic orbits. The waveforms exhibit distinct zoom and whirl phases in a complete orbital period, closely tied to the quantum parameter $\hat{\alpha}$. We also perform a spectral analysis of the gravitational waves from these periodic orbits and assess their detectability. With the steady progress of space-based gravitational wave detection programs, our findings will contribute to utilizing extreme mass-ratio inspirals to test and understand the properties of quantum-corrected black holes. |
gr-qc/9609002 | Michael Reisenberger | Michael P. Reisenberger | A left-handed simplicial action for euclidean general relativity | Version 3. Adds current home address + slight corrections to
references of version 2. Version 2 = substantially clarified form of version
1. 29 pages, 4 figures, Latex, uses psfig.sty to insert postscript figures.
psfig.sty included in mailing, also available from this archive | Class.Quant.Grav. 14 (1997) 1753-1770 | 10.1088/0264-9381/14/7/012 | null | gr-qc | null | An action for simplicial euclidean general relativity involving only
left-handed fields is presented. The simplicial theory is shown to converge to
continuum general relativity in the Plebanski formulation as the simplicial
complex is refined. This contrasts with the Regge model for which Miller and
Brewin have shown that the full field equations are much more restrictive than
Einstein's in the continuum limit. The action and field equations of the
proposed model are also significantly simpler then those of the Regge model
when written directly in terms of their fundamental variables.
An entirely analogous hypercubic lattice theory, which approximates
Plebanski's form of general relativity is also presented.
| [
{
"created": "Fri, 30 Aug 1996 14:14:59 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Apr 1997 23:05:21 GMT",
"version": "v2"
},
{
"created": "Mon, 7 Jul 1997 23:12:19 GMT",
"version": "v3"
}
] | 2009-10-28 | [
[
"Reisenberger",
"Michael P.",
""
]
] | An action for simplicial euclidean general relativity involving only left-handed fields is presented. The simplicial theory is shown to converge to continuum general relativity in the Plebanski formulation as the simplicial complex is refined. This contrasts with the Regge model for which Miller and Brewin have shown that the full field equations are much more restrictive than Einstein's in the continuum limit. The action and field equations of the proposed model are also significantly simpler then those of the Regge model when written directly in terms of their fundamental variables. An entirely analogous hypercubic lattice theory, which approximates Plebanski's form of general relativity is also presented. |
gr-qc/0401072 | Muhammad Sharif | M. Sharif | Momentum and Angular Momentum in the Expanding Universe | null | Astrophys.Space Sci. 262 (1999) 297-304 | null | null | gr-qc | null | A new approach has been used to evaluate the momentum and angular momentum of
the isotropic and homogeneous cosmological models. It is shown that the results
obtained for momentum exactly coincide with those already available in the
literature. However, the angular momentum expression coincides only for the
closed Friedmann model.
| [
{
"created": "Fri, 16 Jan 2004 12:23:40 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Sharif",
"M.",
""
]
] | A new approach has been used to evaluate the momentum and angular momentum of the isotropic and homogeneous cosmological models. It is shown that the results obtained for momentum exactly coincide with those already available in the literature. However, the angular momentum expression coincides only for the closed Friedmann model. |
gr-qc/0509123 | Plamen Fiziev | P. P. Fiziev | Exact Solutions of Regge-Wheeler Equation and Quasi-Normal Modes of
Compact Objects | latex file, 25 pages, 4 figures, new references, new results and new
Appendix added, some comments and corrections in the text made. Accepted for
publication in Classical and Quantum Gravity, 2006, simplification of
notations, changes in the norm in some formulas, corrections in references | Class.Quant.Grav.23:2447-2468,2006 | 10.1088/0264-9381/23/7/015 | SU-THPH-2005-09-01 | gr-qc | null | The well-known Regge-Wheeler equation describes the axial perturbations of
Schwarzschild metric in the linear approximation. From a mathematical point of
view it presents a particular case of the confluent Heun equation and can be
solved exactly, due to recent mathematical developments. We present the basic
properties of its general solution. A novel analytical approach and numerical
techniques for study the boundary problems which correspond to quasi-normal
modes of black holes and other simple models of compact objects are developed.
| [
{
"created": "Fri, 30 Sep 2005 09:11:55 GMT",
"version": "v1"
},
{
"created": "Sun, 2 Oct 2005 13:39:16 GMT",
"version": "v2"
},
{
"created": "Tue, 31 Jan 2006 09:22:34 GMT",
"version": "v3"
},
{
"created": "Mon, 27 Feb 2006 11:10:25 GMT",
"version": "v4"
},
{
"created": "Thu, 16 Mar 2006 17:44:13 GMT",
"version": "v5"
}
] | 2014-11-17 | [
[
"Fiziev",
"P. P.",
""
]
] | The well-known Regge-Wheeler equation describes the axial perturbations of Schwarzschild metric in the linear approximation. From a mathematical point of view it presents a particular case of the confluent Heun equation and can be solved exactly, due to recent mathematical developments. We present the basic properties of its general solution. A novel analytical approach and numerical techniques for study the boundary problems which correspond to quasi-normal modes of black holes and other simple models of compact objects are developed. |
1501.03405 | Ana Hudomal | V. Dmitra\v{s}inovi\'c, Milovan \v{S}uvakov, and Ana Hudomal | Gravitational Waves from Periodic Three-Body Systems | 5 pages, 2 figures | Phys. Rev. Lett. 113, 101102 (2014) | 10.1103/PhysRevLett.113.101102 | null | gr-qc physics.class-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Three bodies moving in a periodic orbit under the influence of Newtonian
gravity ought to emit gravitational waves. We have calculated the gravitational
radiation quadrupolar waveforms and the corresponding luminosities for the
13+11 recently discovered three-body periodic orbits in Newtonian gravity.
These waves clearly allow one to distinguish between their sources: all 13+11
orbits have different waveforms and their luminosities (evaluated at the same
orbit energy and body mass) vary by up to 13 orders of magnitude in the mean,
and up to 20 orders of magnitude for the peak values.
| [
{
"created": "Wed, 14 Jan 2015 16:43:31 GMT",
"version": "v1"
}
] | 2015-01-15 | [
[
"Dmitrašinović",
"V.",
""
],
[
"Šuvakov",
"Milovan",
""
],
[
"Hudomal",
"Ana",
""
]
] | Three bodies moving in a periodic orbit under the influence of Newtonian gravity ought to emit gravitational waves. We have calculated the gravitational radiation quadrupolar waveforms and the corresponding luminosities for the 13+11 recently discovered three-body periodic orbits in Newtonian gravity. These waves clearly allow one to distinguish between their sources: all 13+11 orbits have different waveforms and their luminosities (evaluated at the same orbit energy and body mass) vary by up to 13 orders of magnitude in the mean, and up to 20 orders of magnitude for the peak values. |
2201.12804 | Sreekanth Harikumar | Sreekanth Harikumar, Marek Biesiada | Moffat's Modified Gravity tested on X-COP galaxy clusters | null | null | 10.1140/epjc/s10052-022-10204-4 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | Scalar Tensor Vector Gravity(STVG) is a fully covariant Lorentz invariant
alternative theory of gravity also called as MOdified Gravity(MOG) which
modifies General Relativity(GR) with dynamical massive vector field and scalar
fields. In STVG the mass $\mu$ of the vector field $\phi$ and the Universal
gravitational constant G enjoys the status of a dynamical field. We use the
reconstructed total cluster mass obtained from X-ray observations by XMM-Newton
telescope in combination with the Sunyaev-Zel'dovich(SZ) effect observed within
Planck all-sky survey to estimate the parameters $ \alpha$ and $\mu$ with
modified cluster mass in MOG.
| [
{
"created": "Sun, 30 Jan 2022 12:56:56 GMT",
"version": "v1"
},
{
"created": "Mon, 21 Feb 2022 19:33:24 GMT",
"version": "v2"
}
] | 2022-04-13 | [
[
"Harikumar",
"Sreekanth",
""
],
[
"Biesiada",
"Marek",
""
]
] | Scalar Tensor Vector Gravity(STVG) is a fully covariant Lorentz invariant alternative theory of gravity also called as MOdified Gravity(MOG) which modifies General Relativity(GR) with dynamical massive vector field and scalar fields. In STVG the mass $\mu$ of the vector field $\phi$ and the Universal gravitational constant G enjoys the status of a dynamical field. We use the reconstructed total cluster mass obtained from X-ray observations by XMM-Newton telescope in combination with the Sunyaev-Zel'dovich(SZ) effect observed within Planck all-sky survey to estimate the parameters $ \alpha$ and $\mu$ with modified cluster mass in MOG. |
1308.5008 | Hedvika Kadlecova | Hedvika Kadlecov\'a | Gravitational field of gyratons on various background spacetimes | 155 pages, 10 figures, doctoral thesis | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/3.0/ | In this work we have found and analyzed several gyraton solutions on various
non--trivial backgrounds in the large Kundt class of spacetimes. Namely, the
gyraton solutions on direct product spacetimes, gyraton solutions on Melvin
universe and its generalization which includes the cosmological constant. These
solutions are of algebraic type II. Also we have investigated type III
solutions within the Kundt class and we have found the gyratons on de Sitter
spacetime. We have generalized the gyraton solutions on direct product
spacetimes to higher dimensions. The chapters 4 and 5 are published for the
first time.
| [
{
"created": "Thu, 22 Aug 2013 22:10:55 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Aug 2013 16:41:00 GMT",
"version": "v2"
}
] | 2013-08-27 | [
[
"Kadlecová",
"Hedvika",
""
]
] | In this work we have found and analyzed several gyraton solutions on various non--trivial backgrounds in the large Kundt class of spacetimes. Namely, the gyraton solutions on direct product spacetimes, gyraton solutions on Melvin universe and its generalization which includes the cosmological constant. These solutions are of algebraic type II. Also we have investigated type III solutions within the Kundt class and we have found the gyratons on de Sitter spacetime. We have generalized the gyraton solutions on direct product spacetimes to higher dimensions. The chapters 4 and 5 are published for the first time. |
1005.0779 | Konstantin Yakunin | Konstantin N Yakunin, Pedro Marronetti, Anthony Mezzacappa, Stephen W
Bruenn, Ching-Tsai Lee, Merek A Chertkow, W Raphael Hix, John M Blondin, Eric
J Lentz, O E Bronson Messer and Shin'ichirou Yoshida | Gravitational Waves from Core Collapse Supernovae | 10 pages, 5 figures | Class.Quant.Grav.27:194005,2010 | 10.1088/0264-9381/27/19/194005 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the gravitational wave signatures for a suite of axisymmetric core
collapse supernova models with progenitors masses between 12 and 25 solar
masses. These models are distinguished by the fact they explode and contain
essential physics (in particular, multi-frequency neutrino transport and
general relativity) needed for a more realistic description. Thus, we are able
to compute complete waveforms (i.e., through explosion) based on
non-parameterized, first-principles models. This is essential if the waveform
amplitudes and time scales are to be computed more precisely. Fourier
decomposition shows that the gravitational wave signals we predict should be
observable by AdvLIGO across the range of progenitors considered here. The
fundamental limitation of these models is in their imposition of axisymmetry.
Further progress will require counterpart three-dimensional models.
| [
{
"created": "Wed, 5 May 2010 15:42:42 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Jul 2010 21:21:23 GMT",
"version": "v2"
}
] | 2010-11-03 | [
[
"Yakunin",
"Konstantin N",
""
],
[
"Marronetti",
"Pedro",
""
],
[
"Mezzacappa",
"Anthony",
""
],
[
"Bruenn",
"Stephen W",
""
],
[
"Lee",
"Ching-Tsai",
""
],
[
"Chertkow",
"Merek A",
""
],
[
"Hix",
"W Raphael",
""
],
[
"Blondin",
"John M",
""
],
[
"Lentz",
"Eric J",
""
],
[
"Messer",
"O E Bronson",
""
],
[
"Yoshida",
"Shin'ichirou",
""
]
] | We present the gravitational wave signatures for a suite of axisymmetric core collapse supernova models with progenitors masses between 12 and 25 solar masses. These models are distinguished by the fact they explode and contain essential physics (in particular, multi-frequency neutrino transport and general relativity) needed for a more realistic description. Thus, we are able to compute complete waveforms (i.e., through explosion) based on non-parameterized, first-principles models. This is essential if the waveform amplitudes and time scales are to be computed more precisely. Fourier decomposition shows that the gravitational wave signals we predict should be observable by AdvLIGO across the range of progenitors considered here. The fundamental limitation of these models is in their imposition of axisymmetry. Further progress will require counterpart three-dimensional models. |
1305.0326 | Neil J. Cornish | Neil J. Cornish and A. Sesana | Pulsar Timing Array Analysis for Black Hole Backgrounds | 10 pages, 5 figures | null | 10.1088/0264-9381/30/22/224005 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An astrophysical population of supermassive black hole binaries is thought to
be the strongest source of gravitational waves in the frequency range covered
by Pulsar Timing Arrays (PTAs). A potential cause for concern is that the
standard cross-correlation method used in PTA data analysis assumes that the
signals are isotropically distributed and Gaussian random, while the signals
from a black hole population are likely to be anisotropic and deterministic.
Here we argue that while the conventional analysis is not optimal, it is not
hopeless either, as the standard Hellings-Downs correlation curve turns out to
hold for point sources, and the small effective number of signal samples blurs
the distinction between Gaussian and deterministic signals. Possible
improvements to the standard cross-correlation analysis that account for the
anisotropy of the signal are discussed.
| [
{
"created": "Thu, 2 May 2013 02:10:22 GMT",
"version": "v1"
}
] | 2014-01-23 | [
[
"Cornish",
"Neil J.",
""
],
[
"Sesana",
"A.",
""
]
] | An astrophysical population of supermassive black hole binaries is thought to be the strongest source of gravitational waves in the frequency range covered by Pulsar Timing Arrays (PTAs). A potential cause for concern is that the standard cross-correlation method used in PTA data analysis assumes that the signals are isotropically distributed and Gaussian random, while the signals from a black hole population are likely to be anisotropic and deterministic. Here we argue that while the conventional analysis is not optimal, it is not hopeless either, as the standard Hellings-Downs correlation curve turns out to hold for point sources, and the small effective number of signal samples blurs the distinction between Gaussian and deterministic signals. Possible improvements to the standard cross-correlation analysis that account for the anisotropy of the signal are discussed. |
2107.10360 | Cooper Watson | C. K. Watson, W. Julius, M. Gorban, D. D. McNutt, E. W. Davis, and G.
B. Cleaver | An Invariant Characterization of the Levi-Civita Spacetimes | null | null | 10.3390/sym13081469 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the years 1917-1919 Tullio Levi-Civita published a number of papers
presenting new solutions to Einstein's equations. This work, while partially
translated, remains largely inaccessible to English speaking authors. In this
paper we review these solutions, and present them in a modern, readable manner.
We will also compute both Cartan-Karlhede and Carminati-Mclenaghan invariants
such that these solutions are invariantly characterized by two distinct
methods. These methods will allow for these solutions to be totally, and
invariantly characterized. Because of the variety of solutions considered here,
this paper will also be a useful reference for those seeking to learn to apply
the Cartan-Karlhede algorithm in practice.
| [
{
"created": "Wed, 21 Jul 2021 21:38:25 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Aug 2021 18:41:14 GMT",
"version": "v2"
}
] | 2021-08-17 | [
[
"Watson",
"C. K.",
""
],
[
"Julius",
"W.",
""
],
[
"Gorban",
"M.",
""
],
[
"McNutt",
"D. D.",
""
],
[
"Davis",
"E. W.",
""
],
[
"Cleaver",
"G. B.",
""
]
] | In the years 1917-1919 Tullio Levi-Civita published a number of papers presenting new solutions to Einstein's equations. This work, while partially translated, remains largely inaccessible to English speaking authors. In this paper we review these solutions, and present them in a modern, readable manner. We will also compute both Cartan-Karlhede and Carminati-Mclenaghan invariants such that these solutions are invariantly characterized by two distinct methods. These methods will allow for these solutions to be totally, and invariantly characterized. Because of the variety of solutions considered here, this paper will also be a useful reference for those seeking to learn to apply the Cartan-Karlhede algorithm in practice. |
1810.01259 | Edward Wilson-Ewing | Edward Wilson-Ewing | A relational Hamiltonian for group field theory | 11 pages. v2: Clarifications added, typos corrected and references
added | Phys. Rev. D 99, 086017 (2019) | 10.1103/PhysRevD.99.086017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using a massless scalar field as a clock variable, the Legendre transform of
the group field theory Lagrangian gives a relational Hamiltonian. In the
classical theory, it is natural to define 'equal relational time' Poisson
brackets, where 'equal time' corresponds to equal values of the scalar field
clock. The quantum theory can then be defined by imposing 'equal relational
time' commutation relations for the fundamental operators of the theory, with
the states being elements of a Fock space with their evolution determined by
the relational Hamiltonian operator. A particularly interesting family of
states are condensates, as they are expected to correspond to the cosmological
sector of group field theory. For the relational Hamiltonian considered in this
paper, the coarse-grained dynamics of a simple type of condensate states agree
exactly with the Friedmann equations in the classical limit, and also include
quantum gravity corrections that ensure the big-bang singularity is replaced by
a bounce.
| [
{
"created": "Tue, 2 Oct 2018 14:00:57 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Apr 2019 16:17:45 GMT",
"version": "v2"
}
] | 2019-05-01 | [
[
"Wilson-Ewing",
"Edward",
""
]
] | Using a massless scalar field as a clock variable, the Legendre transform of the group field theory Lagrangian gives a relational Hamiltonian. In the classical theory, it is natural to define 'equal relational time' Poisson brackets, where 'equal time' corresponds to equal values of the scalar field clock. The quantum theory can then be defined by imposing 'equal relational time' commutation relations for the fundamental operators of the theory, with the states being elements of a Fock space with their evolution determined by the relational Hamiltonian operator. A particularly interesting family of states are condensates, as they are expected to correspond to the cosmological sector of group field theory. For the relational Hamiltonian considered in this paper, the coarse-grained dynamics of a simple type of condensate states agree exactly with the Friedmann equations in the classical limit, and also include quantum gravity corrections that ensure the big-bang singularity is replaced by a bounce. |
1905.13723 | Jelle Hartong | Dennis Hansen, Jelle Hartong, Niels A. Obers | Non-relativistic expansion of the Einstein-Hilbert Lagrangian | Proceedings of MG15 meeting, session on Applied Newton-Cartan
Geometry, 6 pages, v2: minor corrections | null | null | EMPG-19-16; NORDITA 2019-052 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a systematic technique to expand the Einstein-Hilbert Lagrangian
in inverse powers of the speed of light squared. The corresponding result for
the non-relativistic gravity Lagrangian is given up to next-to-next-to-leading
order. The techniques are universal and can be used to expand any Lagrangian
theory whose fields are a function of a given parameter.
| [
{
"created": "Fri, 31 May 2019 17:07:40 GMT",
"version": "v1"
},
{
"created": "Wed, 29 Jan 2020 09:20:38 GMT",
"version": "v2"
}
] | 2020-01-30 | [
[
"Hansen",
"Dennis",
""
],
[
"Hartong",
"Jelle",
""
],
[
"Obers",
"Niels A.",
""
]
] | We present a systematic technique to expand the Einstein-Hilbert Lagrangian in inverse powers of the speed of light squared. The corresponding result for the non-relativistic gravity Lagrangian is given up to next-to-next-to-leading order. The techniques are universal and can be used to expand any Lagrangian theory whose fields are a function of a given parameter. |
0707.1079 | M Hossain Ali | M. Hossain Ali | Charged Particles' Tunneling from Hot-NUT-Kerr-Newman-Kasuya Spacetime | To appear in: Int. J. Theor. Phys | Int J Theor Phys (2008) 47: 2203--2217 | 10.1007/s10773-008-9652-y | null | gr-qc hep-th | null | We study the Hawking radiation as charged particles' tunneling across the
horizons of the Hot-NUT-Kerr-Newman-Kasuya spacetime by considering the
spacetime background as dynamical and incorporating the self-gravitation effect
of the emitted particles when the energy conservation, the angular momentum
conservation, and the electric charge conservation are taken into account. Our
result shows that the tunneling rate is related to the change of
Bekenstein-Hawking entropy and the radiant spectrum is not pure thermal, but is
consistent with an underlying unitary theory. The emission process is a
reversible one, and the information is preserved as a natural result of the
first law of black hole thermodynamics.
| [
{
"created": "Sat, 7 Jul 2007 10:18:18 GMT",
"version": "v1"
},
{
"created": "Sat, 10 Nov 2007 06:59:03 GMT",
"version": "v2"
},
{
"created": "Tue, 13 May 2008 04:30:53 GMT",
"version": "v3"
}
] | 2008-08-11 | [
[
"Ali",
"M. Hossain",
""
]
] | We study the Hawking radiation as charged particles' tunneling across the horizons of the Hot-NUT-Kerr-Newman-Kasuya spacetime by considering the spacetime background as dynamical and incorporating the self-gravitation effect of the emitted particles when the energy conservation, the angular momentum conservation, and the electric charge conservation are taken into account. Our result shows that the tunneling rate is related to the change of Bekenstein-Hawking entropy and the radiant spectrum is not pure thermal, but is consistent with an underlying unitary theory. The emission process is a reversible one, and the information is preserved as a natural result of the first law of black hole thermodynamics. |
1910.10473 | Gaurav Khanna | Nur E. M. Rifat, Scott E. Field, Gaurav Khanna, Vijay Varma | A Surrogate Model for Gravitational Wave Signals from Comparable- to
Large- Mass-Ratio Black Hole Binaries | 8 pages, 4 figures; includes improved modeling of the subdominant
modes and a comparison to a high-mass ratio NR simulation; EMRI surrogate
model is now publicly available at bhptoolkit.org | Phys. Rev. D 101, 081502 (2020) | 10.1103/PhysRevD.101.081502 | null | gr-qc astro-ph.HE physics.comp-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational wave signals from compact astrophysical sources such as those
observed by LIGO and Virgo require a high-accuracy, theory-based waveform model
for the analysis of the recorded signal. Current inspiral-merger-ringdown
models are calibrated only up to moderate mass ratios, thereby limiting their
applicability to signals from high-mass ratio binary systems. We present
EMRISur1dq1e4, a reduced-order surrogate model for gravitational waveforms of
13,500M in duration and including several harmonic modes for non-spinning black
hole binary systems with mass-ratios varying from 3 to 10,000 thus vastly
expanding the parameter range beyond the current models. This surrogate model
is trained on waveform data generated by point-particle black hole perturbation
theory (ppBHPT) both for large mass-ratio and comparable mass-ratio binaries.
We observe that the gravitational waveforms generated through a simple
application of ppBHPT to the comparable mass-ratio cases agree remarkably (and
surprisingly) well with those from full numerical relativity after a rescaling
of the ppBHPT's total mass parameter. This observation and the EMRISur1dq1e4
surrogate model will enable data analysis studies in the high-mass ratio
regime, including potential intermediate mass-ratio signals from LIGO/Virgo and
extreme-mass ratio events of interest to the future space-based observatory
LISA.
| [
{
"created": "Wed, 23 Oct 2019 11:41:10 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Apr 2020 00:32:33 GMT",
"version": "v2"
}
] | 2020-04-29 | [
[
"Rifat",
"Nur E. M.",
""
],
[
"Field",
"Scott E.",
""
],
[
"Khanna",
"Gaurav",
""
],
[
"Varma",
"Vijay",
""
]
] | Gravitational wave signals from compact astrophysical sources such as those observed by LIGO and Virgo require a high-accuracy, theory-based waveform model for the analysis of the recorded signal. Current inspiral-merger-ringdown models are calibrated only up to moderate mass ratios, thereby limiting their applicability to signals from high-mass ratio binary systems. We present EMRISur1dq1e4, a reduced-order surrogate model for gravitational waveforms of 13,500M in duration and including several harmonic modes for non-spinning black hole binary systems with mass-ratios varying from 3 to 10,000 thus vastly expanding the parameter range beyond the current models. This surrogate model is trained on waveform data generated by point-particle black hole perturbation theory (ppBHPT) both for large mass-ratio and comparable mass-ratio binaries. We observe that the gravitational waveforms generated through a simple application of ppBHPT to the comparable mass-ratio cases agree remarkably (and surprisingly) well with those from full numerical relativity after a rescaling of the ppBHPT's total mass parameter. This observation and the EMRISur1dq1e4 surrogate model will enable data analysis studies in the high-mass ratio regime, including potential intermediate mass-ratio signals from LIGO/Virgo and extreme-mass ratio events of interest to the future space-based observatory LISA. |
gr-qc/0508025 | Robert Beig | Robert Beig, Michael Wernig-Pichler | On the motion of a compact elastic body | 12 pages, with slight corrections, to be published in
Commun.Math.Phys | Commun.Math.Phys.271:455-465,2007 | 10.1007/s00220-007-0205-7 | null | gr-qc | null | We study the problem of motion of a relativistic, ideal elastic solid with
free surface boundary by casting the equations in material form ("Lagrangian
coordinates"). By applying a basic theorem due to Koch, we prove short-time
existence and uniqueness for solutions close to a trivial solution. This
trivial, or natural, solution corresponds to a stress-free body in rigid
motion.
| [
{
"created": "Sun, 7 Aug 2005 14:09:40 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Feb 2007 13:07:57 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Beig",
"Robert",
""
],
[
"Wernig-Pichler",
"Michael",
""
]
] | We study the problem of motion of a relativistic, ideal elastic solid with free surface boundary by casting the equations in material form ("Lagrangian coordinates"). By applying a basic theorem due to Koch, we prove short-time existence and uniqueness for solutions close to a trivial solution. This trivial, or natural, solution corresponds to a stress-free body in rigid motion. |
1805.03037 | Stefano Viaggiu | Stefano Viaggiu | Statistical description of massless excitations within a sphere with a
linear equation of state and the dark energy case | Accepted for publication on Int. J. Mod. Phys. A | Int. J. Mod. Phys. A, 33, 1850074 (2018) | 10.1142/S0217751X18500744 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we continue the investigations present in \cite{1}-\cite{3}. In
particular, we extend the theorem proved in \cite{3} to any massless excitation
in a given spherical box. As a first interesting result, we show that it is
possible, contrary to the black hole case studied in detail in \cite{1,2,3}, to
build macroscopic configurations with a dark energy equation of state. To this
purpose, by requiring a stable configuration, a macroscopic dark fluid is
obtained with an internal energy $U$ scaling as the volume $V$, but with a
fundamental correction looking like $\sim 1/R$ motivated by quantum
fluctuations. Thanks to the proposition in section 3 (and in \cite{3} for
gravitons), one can depict the dark energy in terms of massless excitations
with a discrete spectrum. This fact open the possibility to test a possible
physical mechanism converting usual radiation into dark energy in a macroscopic
configuration, also in a cosmological context. In fact, for example, in a
Friedmann flat universe with a cosmological constant particles are marginally
trapped at the Hubble horizon for any given comoving observer.
| [
{
"created": "Fri, 4 May 2018 06:27:49 GMT",
"version": "v1"
}
] | 2018-05-09 | [
[
"Viaggiu",
"Stefano",
""
]
] | In this paper we continue the investigations present in \cite{1}-\cite{3}. In particular, we extend the theorem proved in \cite{3} to any massless excitation in a given spherical box. As a first interesting result, we show that it is possible, contrary to the black hole case studied in detail in \cite{1,2,3}, to build macroscopic configurations with a dark energy equation of state. To this purpose, by requiring a stable configuration, a macroscopic dark fluid is obtained with an internal energy $U$ scaling as the volume $V$, but with a fundamental correction looking like $\sim 1/R$ motivated by quantum fluctuations. Thanks to the proposition in section 3 (and in \cite{3} for gravitons), one can depict the dark energy in terms of massless excitations with a discrete spectrum. This fact open the possibility to test a possible physical mechanism converting usual radiation into dark energy in a macroscopic configuration, also in a cosmological context. In fact, for example, in a Friedmann flat universe with a cosmological constant particles are marginally trapped at the Hubble horizon for any given comoving observer. |
1507.04684 | Suresh Kumar | Suresh Kumar | Consistency of the nonflat $\Lambda$CDM model with the new result from
BOSS | 12 pages, 6 figures; Some typos fixed; Matches the version published
in Physical Review D | Phys. Rev. D 92, 103512 (2015) | 10.1103/PhysRevD.92.103512 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using 137,562 quasars in the redshift range $2.1\leq z\leq3.5$ from the Data
Release 11 (DR11) of the Baryon Oscillation Spectroscopic Survey (BOSS) of
Sloan Digital Sky Survey (SDSS)-III, the BOSS-SDSS collaboration estimated the
expansion rate $H(z=2.34)=222\pm7$ km/s/Mpc of Universe, and reported that this
value is in tension with the predictions of flat $\Lambda$CDM model at around
2.5$\sigma$ level. In this paper, we briefly describe some attempts made in the
literature to relieve the tension, and show that the tension can naturally be
alleviated in non-flat $\Lambda$CDM model with positive curvature. We also
perform the observational consistency check by considering the constraints on
the non-flat $\Lambda$CDM model from Planck,WP and BAO data. We find that the
non-flat $\Lambda$CDM model constrained with Planck+WP data fits better to the
line of sight measurement $H(z=2.34)=222\pm7$ km/s/Mpc, but only at the expense
of still having a poor fit to the BAO transverse measurements.
| [
{
"created": "Mon, 13 Jul 2015 13:18:45 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Aug 2015 16:08:51 GMT",
"version": "v2"
},
{
"created": "Wed, 28 Oct 2015 12:06:37 GMT",
"version": "v3"
},
{
"created": "Tue, 1 Dec 2015 12:26:29 GMT",
"version": "v4"
}
] | 2015-12-02 | [
[
"Kumar",
"Suresh",
""
]
] | Using 137,562 quasars in the redshift range $2.1\leq z\leq3.5$ from the Data Release 11 (DR11) of the Baryon Oscillation Spectroscopic Survey (BOSS) of Sloan Digital Sky Survey (SDSS)-III, the BOSS-SDSS collaboration estimated the expansion rate $H(z=2.34)=222\pm7$ km/s/Mpc of Universe, and reported that this value is in tension with the predictions of flat $\Lambda$CDM model at around 2.5$\sigma$ level. In this paper, we briefly describe some attempts made in the literature to relieve the tension, and show that the tension can naturally be alleviated in non-flat $\Lambda$CDM model with positive curvature. We also perform the observational consistency check by considering the constraints on the non-flat $\Lambda$CDM model from Planck,WP and BAO data. We find that the non-flat $\Lambda$CDM model constrained with Planck+WP data fits better to the line of sight measurement $H(z=2.34)=222\pm7$ km/s/Mpc, but only at the expense of still having a poor fit to the BAO transverse measurements. |
2203.11948 | Yurii Ignat'ev | Yu. G. Ignat'ev | Gravitational - Scalar Instability of a Two-Component Degenerate System
of Scalar Charged Fermions with Asymmetric Higgs Interaction | 14 pages, 12 figures, 26 referenses | Gravit. Cosmol. 28 (2022) 25 | 10.1134/S0202289322010078 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on the previously formulated mathematical model of a statistical system
with scalar interaction of fermions and the theory of gravitational-scalar
instability of a cosmological model based on a two-component statistical system
of scalar-charged degenerate fermions, a numerical model of the cosmological
evolution of gravitational-scalar perturbations is constructed and specific
examples of the development of instability are given. Some features of the
instability's development are investigated depending on the nature of the
behavior of the unperturbed cosmological model. It is shown that unstable modes
can appear at very early stages of cosmological expansion or contraction, and
the duration of the unstable phase is comparable to tens of Planck scales. In
this case, however, a very significant increase in unstable modes is possible
due to the redistribution of energy between the components of the scalar
doublet.
| [
{
"created": "Tue, 22 Mar 2022 16:41:22 GMT",
"version": "v1"
}
] | 2022-03-24 | [
[
"Ignat'ev",
"Yu. G.",
""
]
] | Based on the previously formulated mathematical model of a statistical system with scalar interaction of fermions and the theory of gravitational-scalar instability of a cosmological model based on a two-component statistical system of scalar-charged degenerate fermions, a numerical model of the cosmological evolution of gravitational-scalar perturbations is constructed and specific examples of the development of instability are given. Some features of the instability's development are investigated depending on the nature of the behavior of the unperturbed cosmological model. It is shown that unstable modes can appear at very early stages of cosmological expansion or contraction, and the duration of the unstable phase is comparable to tens of Planck scales. In this case, however, a very significant increase in unstable modes is possible due to the redistribution of energy between the components of the scalar doublet. |
2312.15486 | Ghulam Mustafa | G. Mustafa | Ricci inverse gravity wormholes | 14 pages, 11 figures, published in Physics Letters B | null | 10.1016/j.physletb.2023.138407 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The current study deals with the new wormhole solutions in the background of
fourth order new modified Ricci inverse gravity. Two new classes of the
wormhole solutions are analyzed by showing the valid region for the main part
of wormhole geometry under the affect of involved parameters. The embedded
diagrams for both generic shape functions are also presented, which are
connecting upper and lower Universes. In order to check the existence of these
wormhole solutions, energy conditions are included in the current analysis. In
the maximum regions, all energy conditions are violated, which confirms the
presence of exotic matter in the background of Ricci inverse gravity. Stability
analysis for both wormhole solutions is explored within the scope of speed of
sounds parameters. Conclusively, some highlights from this research confirm the
realistic nature and viability of these wormhole solutions in Ricci inverse
gravity.
| [
{
"created": "Sun, 24 Dec 2023 14:17:24 GMT",
"version": "v1"
}
] | 2023-12-27 | [
[
"Mustafa",
"G.",
""
]
] | The current study deals with the new wormhole solutions in the background of fourth order new modified Ricci inverse gravity. Two new classes of the wormhole solutions are analyzed by showing the valid region for the main part of wormhole geometry under the affect of involved parameters. The embedded diagrams for both generic shape functions are also presented, which are connecting upper and lower Universes. In order to check the existence of these wormhole solutions, energy conditions are included in the current analysis. In the maximum regions, all energy conditions are violated, which confirms the presence of exotic matter in the background of Ricci inverse gravity. Stability analysis for both wormhole solutions is explored within the scope of speed of sounds parameters. Conclusively, some highlights from this research confirm the realistic nature and viability of these wormhole solutions in Ricci inverse gravity. |
1609.00824 | Rodrigo Turcati | Ramit Dey, Stefano Liberati, Rodrigo Turcati | AdS and dS black hole solutions in analogue gravity: The relativistic
and non-relativistic cases | 10 pages. Final version matching the published one in PRD | Phys. Rev. D 94, 104068 (2016) | 10.1103/PhysRevD.94.104068 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that Schwarzschild black hole solutions in asymptotically Anti-de
Sitter (AdS) and de Sitter (dS) spaces may, up to a conformal factor, be
reproduced in the framework of analogue gravity. The aforementioned derivation
is performed using relativistic and non-relativistic Bose-Einstein condensates.
In addition, we demonstrate that the (2+1) planar AdS black hole can be mapped
into the non-relativistic acoustic metric. Given that AdS black holes are
extensively employed in the gauge/gravity duality, we then comment on the
possibility to study the AdS/CFT correspondence and gravity/fluid duality from
an analogue gravity perspective.
| [
{
"created": "Sat, 3 Sep 2016 12:47:40 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Nov 2016 00:36:14 GMT",
"version": "v2"
}
] | 2016-12-01 | [
[
"Dey",
"Ramit",
""
],
[
"Liberati",
"Stefano",
""
],
[
"Turcati",
"Rodrigo",
""
]
] | We show that Schwarzschild black hole solutions in asymptotically Anti-de Sitter (AdS) and de Sitter (dS) spaces may, up to a conformal factor, be reproduced in the framework of analogue gravity. The aforementioned derivation is performed using relativistic and non-relativistic Bose-Einstein condensates. In addition, we demonstrate that the (2+1) planar AdS black hole can be mapped into the non-relativistic acoustic metric. Given that AdS black holes are extensively employed in the gauge/gravity duality, we then comment on the possibility to study the AdS/CFT correspondence and gravity/fluid duality from an analogue gravity perspective. |
1008.1964 | Foek Hioe | F.T. Hioe and David Kuebel | Hyperbolic-Type Orbits in the Schwarzschild Metric | 31 pages total, 8 tables, and 6 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Exact analytic expressions for various characteristics of the hyperbolic-type
orbits of a particle in the Schwarzschild geometry are presented. A useful
simple approximation formula is given for the case when the deviation from the
Newtonian hyperbolic path is very small.
| [
{
"created": "Wed, 11 Aug 2010 18:11:19 GMT",
"version": "v1"
}
] | 2010-08-12 | [
[
"Hioe",
"F. T.",
""
],
[
"Kuebel",
"David",
""
]
] | Exact analytic expressions for various characteristics of the hyperbolic-type orbits of a particle in the Schwarzschild geometry are presented. A useful simple approximation formula is given for the case when the deviation from the Newtonian hyperbolic path is very small. |
gr-qc/0409110 | Patricio S. Letelier | Maximiliano Ujevic and Patricio S. Letelier | On the stability of general relativistic geometric thin disks | 11 pages, RevTex. Phys Rev D (in press) | Phys.Rev. D70 (2004) 084015 | 10.1103/PhysRevD.70.084015 | null | gr-qc astro-ph | null | The stability of general relativistic thin disks is investigated under a
general first order perturbation of the energy momentum tensor. In particular,
we consider temporal, radial and azimuthal "test matter" perturbations of the
quantities involved on the plane $z=0$. We study the thin disks generated by
applying the "displace, cut and reflect" method, usually known as the image
method, to the Schwarzschild metric in isotropic coordinates and to the
Chazy-Curzon metric and the Zipoy-Voorhees metric ($\gamma$-metric) in Weyl
coordinates. In the case of the isotropic Schwarzschild thin disk, where a
radial pressure is present to support the gravitational attraction, the disk is
stable and the perturbation favors the formation of rings. Also, we found the
expected result that the thin disk models generated by the Chazy-Curzon and
Zipoy-Voorhees metric with only azimuthal pressure are not stable under a
general first order perturbation
| [
{
"created": "Tue, 28 Sep 2004 17:41:17 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Ujevic",
"Maximiliano",
""
],
[
"Letelier",
"Patricio S.",
""
]
] | The stability of general relativistic thin disks is investigated under a general first order perturbation of the energy momentum tensor. In particular, we consider temporal, radial and azimuthal "test matter" perturbations of the quantities involved on the plane $z=0$. We study the thin disks generated by applying the "displace, cut and reflect" method, usually known as the image method, to the Schwarzschild metric in isotropic coordinates and to the Chazy-Curzon metric and the Zipoy-Voorhees metric ($\gamma$-metric) in Weyl coordinates. In the case of the isotropic Schwarzschild thin disk, where a radial pressure is present to support the gravitational attraction, the disk is stable and the perturbation favors the formation of rings. Also, we found the expected result that the thin disk models generated by the Chazy-Curzon and Zipoy-Voorhees metric with only azimuthal pressure are not stable under a general first order perturbation |
2307.08697 | Tomas Andrade | Tomas Andrade, Juan Trenado, Simone Albanesi, Rossella Gamba,
Sebastiano Bernuzzi, Alessandro Nagar, Juan Calderon-Bustillo, Nicolas
Sanchis-Gual, Jose A. Font, William Cook, Boris Daszuta, Francesco Zappa, and
David Radice | Towards numerical-relativity informed effective-one-body waveforms for
dynamical capture black hole binaries | 21 pages, 15 figures | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Dynamical captures of black holes may take place in dense stellar media due
to the emission of gravitational radiation during a close passage. Detection of
such events requires detailed modelling, since their phenomenology
qualitatively differs from that of quasi-circular binaries. Very few models can
deliver such waveforms, and none includes information from Numerical Relativity
(NR) simulations of non quasi-circular coalescences. In this study we present a
first step towards a fully NR-informed Effective One Body (EOB) model of
dynamical captures. We perform 14 new simulations of single and double
encounter mergers, and use this data to inform the merger-ringdown model of the
TEOBResumS-Dali approximant. We keep the initial energy approximately fixed to
the binary mass, and vary the mass-rescaled, dimensionless angular momentum in
the range $(0.6, 1.1)$, the mass ratio in $(1, 2.15)$ and aligned dimensionless
spins in $(-0.5, 0.5)$. We find that the model is able to match NR to $97%$,
improving previous performances, without the need of modifying the base-line
template. Upon NR informing the model, this improves to $99%$ with the
exception of one outlier corresponding to a direct plunge. The maximum EOBNR
phase difference at merger for the uninformed model is of $0.15$ radians, which
is reduced to $0.1$ radians after the NR information is introduced. We outline
the steps towards a fully informed EOB model of dynamical captures, and discuss
future improvements.
| [
{
"created": "Mon, 17 Jul 2023 17:57:45 GMT",
"version": "v1"
}
] | 2023-07-18 | [
[
"Andrade",
"Tomas",
""
],
[
"Trenado",
"Juan",
""
],
[
"Albanesi",
"Simone",
""
],
[
"Gamba",
"Rossella",
""
],
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Nagar",
"Alessandro",
""
],
[
"Calderon-Bustillo",
"Juan",
""
],
[
"Sanchis-Gual",
"Nicolas",
""
],
[
"Font",
"Jose A.",
""
],
[
"Cook",
"William",
""
],
[
"Daszuta",
"Boris",
""
],
[
"Zappa",
"Francesco",
""
],
[
"Radice",
"David",
""
]
] | Dynamical captures of black holes may take place in dense stellar media due to the emission of gravitational radiation during a close passage. Detection of such events requires detailed modelling, since their phenomenology qualitatively differs from that of quasi-circular binaries. Very few models can deliver such waveforms, and none includes information from Numerical Relativity (NR) simulations of non quasi-circular coalescences. In this study we present a first step towards a fully NR-informed Effective One Body (EOB) model of dynamical captures. We perform 14 new simulations of single and double encounter mergers, and use this data to inform the merger-ringdown model of the TEOBResumS-Dali approximant. We keep the initial energy approximately fixed to the binary mass, and vary the mass-rescaled, dimensionless angular momentum in the range $(0.6, 1.1)$, the mass ratio in $(1, 2.15)$ and aligned dimensionless spins in $(-0.5, 0.5)$. We find that the model is able to match NR to $97%$, improving previous performances, without the need of modifying the base-line template. Upon NR informing the model, this improves to $99%$ with the exception of one outlier corresponding to a direct plunge. The maximum EOBNR phase difference at merger for the uninformed model is of $0.15$ radians, which is reduced to $0.1$ radians after the NR information is introduced. We outline the steps towards a fully informed EOB model of dynamical captures, and discuss future improvements. |
gr-qc/9904005 | Shinji Mukohyama | Shinji Mukohyama | Hartle-Hawking state is a maximum of entanglement entropy | Latex, 4 pages, Some comments are added on the "small backreaction
condition" | Phys.Rev. D61 (2000) 064015 | 10.1103/PhysRevD.61.064015 | YITP-99-17 | gr-qc hep-th | null | It is shown that the Hartle-Hawking state of a scalar field is a maximum of
entanglement entropy in the space of pure quantum states satisfying the
condition that backreaction is finite. In other words, the Hartle-Hawking state
is a curved-space analogue of the EPR state, which is also a maximum of
entanglement entropy.
| [
{
"created": "Fri, 2 Apr 1999 06:20:16 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Aug 1999 19:43:14 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Mukohyama",
"Shinji",
""
]
] | It is shown that the Hartle-Hawking state of a scalar field is a maximum of entanglement entropy in the space of pure quantum states satisfying the condition that backreaction is finite. In other words, the Hartle-Hawking state is a curved-space analogue of the EPR state, which is also a maximum of entanglement entropy. |
gr-qc/0309044 | L. K. Chavda | L.K.Chavda and Abhijit L.Chavda | Holeum,enigmas of cosmology and gravitational waves | 11 pages,1 table,formation of Holeum-stars in the galactic haloes and
the domain walls added,new keyword added,Discussion and Conclusions
revised,PDF | null | null | null | gr-qc astro-ph | null | The principle of nuclear democracy is invoked to prove the formation of
stable quantized gravitational bound states of primordial black holes called
Holeums. The latter come in four varieties: ordinary Holeums H, Black Holeums
BH, Hyper Holeums HH and the massless Lux Holeums LH.These Holeums are
invisible because the gravitational radiation emitted by their quantum
transitions is undetectable now. The copiously produced Holeums form an
important component of the dark matter and the Lux Holeums an important
component of the dark energy in the universe. A segregation property puts the
Holeums mainly in the galactic haloes (GH) and the domain walls (DW) explaining
the latters' invisibility now. Cosmic rays (CR) are produced by two exploding
black holes created in a pressure-ionization of a stable Holeum. Our prediction
that more CRs will be emitted by the haloes than by the discs of galaxies
already has a strong empirical support. The concentration of the Hs and the HHs
in the GHs and the DWs lead to the formation of Holeum-stars emitting the CRs
and the gravitational waves(GW).Innumerable explosions of BHs at the time of
decoupling of gravity from the other interactions lead to inflation and baryon
asymmetry. A substantial cosmic back ground of matter and GWs and an
infra-quantum gravity (infra-QG) band and an ultra-QG band of GWs and their
emission frequencies are predicted. A unique quantum system containing
matter-energy oscillations is found.
| [
{
"created": "Mon, 8 Sep 2003 12:30:51 GMT",
"version": "v1"
},
{
"created": "Sat, 27 Sep 2003 11:28:43 GMT",
"version": "v2"
},
{
"created": "Thu, 24 Jun 2004 11:05:09 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Chavda",
"L. K.",
""
],
[
"Chavda",
"Abhijit L.",
""
]
] | The principle of nuclear democracy is invoked to prove the formation of stable quantized gravitational bound states of primordial black holes called Holeums. The latter come in four varieties: ordinary Holeums H, Black Holeums BH, Hyper Holeums HH and the massless Lux Holeums LH.These Holeums are invisible because the gravitational radiation emitted by their quantum transitions is undetectable now. The copiously produced Holeums form an important component of the dark matter and the Lux Holeums an important component of the dark energy in the universe. A segregation property puts the Holeums mainly in the galactic haloes (GH) and the domain walls (DW) explaining the latters' invisibility now. Cosmic rays (CR) are produced by two exploding black holes created in a pressure-ionization of a stable Holeum. Our prediction that more CRs will be emitted by the haloes than by the discs of galaxies already has a strong empirical support. The concentration of the Hs and the HHs in the GHs and the DWs lead to the formation of Holeum-stars emitting the CRs and the gravitational waves(GW).Innumerable explosions of BHs at the time of decoupling of gravity from the other interactions lead to inflation and baryon asymmetry. A substantial cosmic back ground of matter and GWs and an infra-quantum gravity (infra-QG) band and an ultra-QG band of GWs and their emission frequencies are predicted. A unique quantum system containing matter-energy oscillations is found. |
0811.0782 | Saibal Ray | U. Mukhopadhyay, Saibal Ray, A. A. Usmani and Partha Pratim Ghosh | Time variable $\Lambda$ and the accelerating Universe | Latex, 10 pages, 2 figures, accepted in IJTP | Int.J.Theor.Phys.50:752-759,2011 | 10.1007/s10773-010-0611-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform a deductive study of accelerating Universe and focus on the
importance of variable time-dependent $\Lambda$ in the Einstein's field
equations under the phenomenological assumption, $\Lambda =\alpha H^2$ for the
full physical range of $\alpha$. The relevance of variable $\Lambda$ with
regard to various key issues like dark matter, dark energy, geometry of the
field, age of the Universe, deceleration parameter and barotropic equation of
state has been trivially addressed. The deceleration parameter and the
barotropic equation of state parameter obey a straight line relationship for a
flat Universe described by Friedmann and Raychaudhuri equations. Both the
parameters are found identical for $\alpha = 1$.
| [
{
"created": "Wed, 5 Nov 2008 17:40:23 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Nov 2008 20:25:43 GMT",
"version": "v2"
},
{
"created": "Thu, 9 Dec 2010 10:10:01 GMT",
"version": "v3"
}
] | 2011-01-25 | [
[
"Mukhopadhyay",
"U.",
""
],
[
"Ray",
"Saibal",
""
],
[
"Usmani",
"A. A.",
""
],
[
"Ghosh",
"Partha Pratim",
""
]
] | We perform a deductive study of accelerating Universe and focus on the importance of variable time-dependent $\Lambda$ in the Einstein's field equations under the phenomenological assumption, $\Lambda =\alpha H^2$ for the full physical range of $\alpha$. The relevance of variable $\Lambda$ with regard to various key issues like dark matter, dark energy, geometry of the field, age of the Universe, deceleration parameter and barotropic equation of state has been trivially addressed. The deceleration parameter and the barotropic equation of state parameter obey a straight line relationship for a flat Universe described by Friedmann and Raychaudhuri equations. Both the parameters are found identical for $\alpha = 1$. |
1302.3791 | Victor Eugen Ambru\c{s} | Victor E. Ambru\c{s} and Elizabeth Winstanley | Rotating fermions | 4 pages, 1 figure, Marcel Grossmann 13 meeting proceedings | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the rigidly rotating quantum thermal distribution of fermions
in flat space-time. We find that thermal states diverge on the speed of light
surface. We remove the divergences by enclosing the system inside a cylindrical
boundary and investigate thermal expectation values and the Casimir effect for
two sets of boundary conditions.
| [
{
"created": "Fri, 15 Feb 2013 16:14:04 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Feb 2013 18:47:31 GMT",
"version": "v2"
}
] | 2013-02-19 | [
[
"Ambruş",
"Victor E.",
""
],
[
"Winstanley",
"Elizabeth",
""
]
] | We investigate the rigidly rotating quantum thermal distribution of fermions in flat space-time. We find that thermal states diverge on the speed of light surface. We remove the divergences by enclosing the system inside a cylindrical boundary and investigate thermal expectation values and the Casimir effect for two sets of boundary conditions. |
2001.11439 | Aleksandar Mikovic | Aleksandar Mikovic | Piecewise Flat Metrics and Quantum Gravity | 17 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce a physical piecewise linear metric associated to a Regge
triangulation of a smooth 4-manifold. We describe the basic properties of the
corresponding geometry in the cases of the Euclidean and the Minkowski
signature. In the Minkowski case, we describe the Regge action and how to
define the corresponding path integral for the casual triangulations. We also
discus the Regge path integral for a triangulation associated to the
Friedman-Lemaitre-Robertson-Walker cosmological model and briefly study the
corresponding wavefunctions, namely the Hartle-Hawking and the Vilenkin
wavefunction.
| [
{
"created": "Thu, 30 Jan 2020 16:38:02 GMT",
"version": "v1"
}
] | 2020-01-31 | [
[
"Mikovic",
"Aleksandar",
""
]
] | We introduce a physical piecewise linear metric associated to a Regge triangulation of a smooth 4-manifold. We describe the basic properties of the corresponding geometry in the cases of the Euclidean and the Minkowski signature. In the Minkowski case, we describe the Regge action and how to define the corresponding path integral for the casual triangulations. We also discus the Regge path integral for a triangulation associated to the Friedman-Lemaitre-Robertson-Walker cosmological model and briefly study the corresponding wavefunctions, namely the Hartle-Hawking and the Vilenkin wavefunction. |
2202.02480 | Woei Chet Lim | Woei Chet Lim | Numerical confirmations of joint spike transitions in $G_2$ cosmologies | 18 pages, 5 figures | Class. Quantum Grav. 39 (2022) 065010 | 10.1088/1361-6382/ac5011 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We produce numerical evidence that the joint spike transitions between Kasner
eras of $G_2$ cosmologies are described by the non-orthogonally transitive
$G_2$ spike solution. A new matching procedure is developed for this purpose.
| [
{
"created": "Sat, 5 Feb 2022 03:31:19 GMT",
"version": "v1"
}
] | 2022-02-22 | [
[
"Lim",
"Woei Chet",
""
]
] | We produce numerical evidence that the joint spike transitions between Kasner eras of $G_2$ cosmologies are described by the non-orthogonally transitive $G_2$ spike solution. A new matching procedure is developed for this purpose. |
1002.1533 | Nima Khosravi | Nima Khosravi | Particle Creation from Vacuum by Lorentz Violation | 9 pages, 2 figures | Gen.Rel.Grav.43:1417-1426,2011 | 10.1007/s10714-010-1124-z | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that the vacuum state in presence of Lorentz violation can be
followed by a particle-full universe that represents the current status of the
universe. In this model the modification in dispersion relation (Lorentz
violation) is picked up representing the regime of quantum gravity. The result
can be interpreted such that the existence of the particles is an evidence for
quantum effects of gravity in the past. It is concluded that only the vacuum
state is sufficient to appear the matter fields spontaneously after the process
of semi-classical analysis.
| [
{
"created": "Mon, 8 Feb 2010 06:00:45 GMT",
"version": "v1"
}
] | 2011-04-22 | [
[
"Khosravi",
"Nima",
""
]
] | It is shown that the vacuum state in presence of Lorentz violation can be followed by a particle-full universe that represents the current status of the universe. In this model the modification in dispersion relation (Lorentz violation) is picked up representing the regime of quantum gravity. The result can be interpreted such that the existence of the particles is an evidence for quantum effects of gravity in the past. It is concluded that only the vacuum state is sufficient to appear the matter fields spontaneously after the process of semi-classical analysis. |
2012.07973 | Joseph Schindler | Joseph Schindler, Evan Frangipane, Anthony Aguirre | Unitarity and the information problem in an explicit model of black hole
evaporation | 14 pages, 11 figures. v2: additional references | Class. Quantum Grav. 38 075025 (2021) | 10.1088/1361-6382/abdf25 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the black hole information problem in an explicitly defined
spacetime modelling black hole evaporation. Using this context we review basic
aspects of the problem, with a particular effort to be unambiguous about subtle
topics, for instance precisely what is meant by entropy in various
circumstances. We then focus on questions of unitarity, and argue that commonly
invoked semiclassical statements of long term, evaporation time, and Page time
"unitarity" may all be violated even if physics is fundamentally unitary. This
suggests that there is no horizon firewall. We discuss how the picture is
modified for regular (nonsingular) evaporation models. We also compare our
conclusions to recent holographic studies, and argue that they are mutually
compatible.
| [
{
"created": "Mon, 14 Dec 2020 22:15:48 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Apr 2021 18:14:57 GMT",
"version": "v2"
}
] | 2021-04-16 | [
[
"Schindler",
"Joseph",
""
],
[
"Frangipane",
"Evan",
""
],
[
"Aguirre",
"Anthony",
""
]
] | We consider the black hole information problem in an explicitly defined spacetime modelling black hole evaporation. Using this context we review basic aspects of the problem, with a particular effort to be unambiguous about subtle topics, for instance precisely what is meant by entropy in various circumstances. We then focus on questions of unitarity, and argue that commonly invoked semiclassical statements of long term, evaporation time, and Page time "unitarity" may all be violated even if physics is fundamentally unitary. This suggests that there is no horizon firewall. We discuss how the picture is modified for regular (nonsingular) evaporation models. We also compare our conclusions to recent holographic studies, and argue that they are mutually compatible. |
gr-qc/0102009 | Parampreet Singh | Naresh Dadhich | Subtle is the Gravity | This is the Vaidya - Raichaudhary Endowment Fund Award Lecture
delivered on 30th Jan. 01 at the 21st meeting of IAGRG, held at Nagpur | null | null | null | gr-qc astro-ph hep-th physics.class-ph | null | In this lecture I build up the motivation for relativity and gravitation
based on general principles and common sense considerations which should fall
in the sphere of appreciation of a general reader. There is a novel way of
looking at things and understanding them in a more direct physical terms which
should be of interest to fellow relativists as well as physicists in general.
| [
{
"created": "Sat, 3 Feb 2001 08:15:13 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Dadhich",
"Naresh",
""
]
] | In this lecture I build up the motivation for relativity and gravitation based on general principles and common sense considerations which should fall in the sphere of appreciation of a general reader. There is a novel way of looking at things and understanding them in a more direct physical terms which should be of interest to fellow relativists as well as physicists in general. |
1512.06768 | Jan Steinhoff | Jan Steinhoff | Spin effects on the dynamics of compact binaries | 7 pages, Proceedings of the 14th Marcel Grossman Meeting. v2: added
ref | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Compact binaries are the most promising source for the advanced gravitational
wave detectors, which will start operating this year. The influence of spin on
the binary evolution is an important consequence of general relativity and can
be large. It is argued that the spin supplementary condition, which is related
to the observer dependence of the center, gives rise to a gauge symmetry in the
action principle of spinning point-particles. These spinning point-particles
serve as an analytic model for extended bodies. The internal structure can be
modelled by augmenting the point-particle with higher-order multipole moments.
Consequences of the recently discovered universal (equation of state
independent) relations between the multipole moments of neutron stars are
discussed.
| [
{
"created": "Mon, 21 Dec 2015 19:00:05 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Jan 2016 20:30:56 GMT",
"version": "v2"
}
] | 2016-01-28 | [
[
"Steinhoff",
"Jan",
""
]
] | Compact binaries are the most promising source for the advanced gravitational wave detectors, which will start operating this year. The influence of spin on the binary evolution is an important consequence of general relativity and can be large. It is argued that the spin supplementary condition, which is related to the observer dependence of the center, gives rise to a gauge symmetry in the action principle of spinning point-particles. These spinning point-particles serve as an analytic model for extended bodies. The internal structure can be modelled by augmenting the point-particle with higher-order multipole moments. Consequences of the recently discovered universal (equation of state independent) relations between the multipole moments of neutron stars are discussed. |
1708.09228 | Gyula Fodor | Gyula Fodor and P\'eter Forg\'acs | Anti-de Sitter geon families | 65 pages, minor changes | null | 10.1103/PhysRevD.96.084027 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A detailed perturbative construction of globally regular, asymptotically
anti-de Sitter (AdS) time-periodic solutions of Einstein's equations with a
negative cosmological constant (AdS geons) is presented. Starting with the most
general superposition of the $l=2$ even parity (scalar) eigenmodes of AdS at
linear order, it is shown that at the fifth order in perturbation theory one
obtains five one-parameter geon families, two of which have a helical Killing
vector, one with axial symmetry, and two others without continuous symmetries.
The details and some subtle aspects of the perturbative expansions are also
presented.
| [
{
"created": "Wed, 30 Aug 2017 12:04:01 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Oct 2017 12:53:46 GMT",
"version": "v2"
}
] | 2017-10-25 | [
[
"Fodor",
"Gyula",
""
],
[
"Forgács",
"Péter",
""
]
] | A detailed perturbative construction of globally regular, asymptotically anti-de Sitter (AdS) time-periodic solutions of Einstein's equations with a negative cosmological constant (AdS geons) is presented. Starting with the most general superposition of the $l=2$ even parity (scalar) eigenmodes of AdS at linear order, it is shown that at the fifth order in perturbation theory one obtains five one-parameter geon families, two of which have a helical Killing vector, one with axial symmetry, and two others without continuous symmetries. The details and some subtle aspects of the perturbative expansions are also presented. |
gr-qc/0404079 | J. Alberto Lobo | J. Alberto Lobo | Lisa | 22 pages, LaTeX2e, PS/EPS figures, talk given at ERE-2003, Alicante
(Spain), September-2003, will appear in Conference Proceedings | null | null | null | gr-qc | null | The extreme weakness of the gravitational interaction has as one of its
consequences that appreciable intensities of gravitational waves (GW) can only
be generated in large size astrophysical and cosmological sources. Earth based
detectors face unsurmountable problems to be sensitive to signals at
frequencies below 10 Hz due to seismic vibrations. In order to see lower
frequency signals, a space based detector is the natural solution. LISA (Laser
Interferometer Space Antenna) is a joint ESA-NASA project aimed at detecting
GWs in a range of frequencies between 10^{-4} Hz and 10^{-1} Hz, and consists
in a constellation of three spacecraft in heliocentric orbit, whose GW-induced
armlength variations are monitored by high precision interferometry. This
article reviews the main features and scientific goals of the LISA mission, as
well as a shorter description of its precursor tecnological mission LPF (LISA
Pathfinder).
| [
{
"created": "Sat, 17 Apr 2004 13:09:02 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Lobo",
"J. Alberto",
""
]
] | The extreme weakness of the gravitational interaction has as one of its consequences that appreciable intensities of gravitational waves (GW) can only be generated in large size astrophysical and cosmological sources. Earth based detectors face unsurmountable problems to be sensitive to signals at frequencies below 10 Hz due to seismic vibrations. In order to see lower frequency signals, a space based detector is the natural solution. LISA (Laser Interferometer Space Antenna) is a joint ESA-NASA project aimed at detecting GWs in a range of frequencies between 10^{-4} Hz and 10^{-1} Hz, and consists in a constellation of three spacecraft in heliocentric orbit, whose GW-induced armlength variations are monitored by high precision interferometry. This article reviews the main features and scientific goals of the LISA mission, as well as a shorter description of its precursor tecnological mission LPF (LISA Pathfinder). |
2005.05534 | Snehasish Bhattacharjee | Snehasish Bhattacharjee | Gravitational baryogenesis in extended teleparallel theories of gravity | Published in Physics of the Dark Universe | Physics of the Dark Universe, 30 (2020) 100612 | 10.1016/j.dark.2020.100612 | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | The article communicates gravitational baryogenesis in non-minimal $f(T)$
gravity and $f(T,B)$ teleparallel gravity where $T$ denote the torsion scalar
and $B$ a boundary term. These extended teleparallel theories of gravity differ
from the usual $f(T)$ gravity and therefore could provide key insights in
expounding the baryon asymmetry of the universe. Furthermore, such a study also
put constraints on the model parameters of these extended teleparallel theory
of gravity. I present different baryogenesis interactions proportional to
$\partial_{i}T$, $\partial_{i}f(T)$, $\partial_{i}(T+B)$ and
$\partial_{i}f(T+B)$ and find that both of these teleparallel theories of
gravity yield viable estimates of the baron-to-entropy ratio compatible with
observations except for the baryogenesis interaction proportional to
$\partial_{i}(T+B)$. It is therefore encouraging to exercise these extended
theories of gravity in other cosmological areas to under their efficiency and
applicability in characterizing the current state of the universe.
| [
{
"created": "Tue, 12 May 2020 03:26:37 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Jun 2020 03:52:52 GMT",
"version": "v2"
}
] | 2020-06-08 | [
[
"Bhattacharjee",
"Snehasish",
""
]
] | The article communicates gravitational baryogenesis in non-minimal $f(T)$ gravity and $f(T,B)$ teleparallel gravity where $T$ denote the torsion scalar and $B$ a boundary term. These extended teleparallel theories of gravity differ from the usual $f(T)$ gravity and therefore could provide key insights in expounding the baryon asymmetry of the universe. Furthermore, such a study also put constraints on the model parameters of these extended teleparallel theory of gravity. I present different baryogenesis interactions proportional to $\partial_{i}T$, $\partial_{i}f(T)$, $\partial_{i}(T+B)$ and $\partial_{i}f(T+B)$ and find that both of these teleparallel theories of gravity yield viable estimates of the baron-to-entropy ratio compatible with observations except for the baryogenesis interaction proportional to $\partial_{i}(T+B)$. It is therefore encouraging to exercise these extended theories of gravity in other cosmological areas to under their efficiency and applicability in characterizing the current state of the universe. |
1105.0781 | Barry Wardell | Ian Hinder, Barry Wardell and Eloisa Bentivegna | Falloff of the Weyl scalars in binary black hole spacetimes | 7 pages, 3 figures, published version | Phys.Rev.D84:024036,2011 | 10.1103/PhysRevD.84.024036 | AEI-2011-025 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The peeling theorem of general relativity predicts that the Weyl curvature
scalars Psi_n (n=0...4), when constructed from a suitable null tetrad in an
asymptotically flat spacetime, fall off asymptotically as r^(n-5) along
outgoing radial null geodesics. This leads to the interpretation of Psi_4 as
outgoing gravitational radiation at large distances from the source. We have
performed numerical simulations in full general relativity of a binary black
hole inspiral and merger, and have computed the Weyl scalars in the standard
tetrad used in numerical relativity. In contrast with previous results, we
observe that all the Weyl scalars fall off according to the predictions of the
theorem.
| [
{
"created": "Wed, 4 May 2011 10:03:46 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Jun 2013 16:51:10 GMT",
"version": "v2"
}
] | 2013-06-13 | [
[
"Hinder",
"Ian",
""
],
[
"Wardell",
"Barry",
""
],
[
"Bentivegna",
"Eloisa",
""
]
] | The peeling theorem of general relativity predicts that the Weyl curvature scalars Psi_n (n=0...4), when constructed from a suitable null tetrad in an asymptotically flat spacetime, fall off asymptotically as r^(n-5) along outgoing radial null geodesics. This leads to the interpretation of Psi_4 as outgoing gravitational radiation at large distances from the source. We have performed numerical simulations in full general relativity of a binary black hole inspiral and merger, and have computed the Weyl scalars in the standard tetrad used in numerical relativity. In contrast with previous results, we observe that all the Weyl scalars fall off according to the predictions of the theorem. |
2308.00897 | Gansukh Tumurtushaa | Seoktae Koh, Seong Chan Park, and Gansukh Tumurtushaa | Higgs Inflation with a Gauss-Bonnet term | 11 pages, three figures (Fig. 1 and related text updated),
comments/suggestions welcome | null | null | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | Higgs inflation with a Gauss-Bonnet term is studied in the Einstein frame.
Our model features two coupling functions, $\Omega^2(\phi)$ and $\omega(\phi)$,
coupled to the Ricci scalar and Gauss-Bonnet combinations. We found a special
relation $\Omega^2 \propto \omega$ sets the system a lot more simplified;
therefore, we take it for granted in our analytical studies. As a result of a
Weyl transformation to the Einstein frame, we notice the emergence of new
interactions: a non-minimal kinetic coupling between the scalar field and
gravity and a derivative self-interaction of the scalar field. In the Einstein
frame, we investigate the cosmological implications of these interactions by
deriving the background equation of motion and observable quantities. Our
numerical result on $n_S$ vs. $r$ suggests our model is consistent with the
observational data for a wide range of the model parameter, $-1.4\times
10^4\lesssim \alpha \equiv \frac{\omega}{\Omega^2} \lesssim 8\times 10^3$,
where both the positive and negative values of $\alpha$ are allowed. As the
Gauss-Bonnet contributions decay away with time after inflation, the
propagation speed of gravitational waves turned out to be consistent with the
recent constraints on the propagation speed of gravitational waves (GWs)
without inducing ghost instability.
| [
{
"created": "Wed, 2 Aug 2023 01:26:17 GMT",
"version": "v1"
},
{
"created": "Sat, 19 Aug 2023 07:39:56 GMT",
"version": "v2"
},
{
"created": "Sat, 23 Mar 2024 07:07:21 GMT",
"version": "v3"
}
] | 2024-03-26 | [
[
"Koh",
"Seoktae",
""
],
[
"Park",
"Seong Chan",
""
],
[
"Tumurtushaa",
"Gansukh",
""
]
] | Higgs inflation with a Gauss-Bonnet term is studied in the Einstein frame. Our model features two coupling functions, $\Omega^2(\phi)$ and $\omega(\phi)$, coupled to the Ricci scalar and Gauss-Bonnet combinations. We found a special relation $\Omega^2 \propto \omega$ sets the system a lot more simplified; therefore, we take it for granted in our analytical studies. As a result of a Weyl transformation to the Einstein frame, we notice the emergence of new interactions: a non-minimal kinetic coupling between the scalar field and gravity and a derivative self-interaction of the scalar field. In the Einstein frame, we investigate the cosmological implications of these interactions by deriving the background equation of motion and observable quantities. Our numerical result on $n_S$ vs. $r$ suggests our model is consistent with the observational data for a wide range of the model parameter, $-1.4\times 10^4\lesssim \alpha \equiv \frac{\omega}{\Omega^2} \lesssim 8\times 10^3$, where both the positive and negative values of $\alpha$ are allowed. As the Gauss-Bonnet contributions decay away with time after inflation, the propagation speed of gravitational waves turned out to be consistent with the recent constraints on the propagation speed of gravitational waves (GWs) without inducing ghost instability. |
gr-qc/0703152 | Matthew Pitkin | Matthew Pitkin and Graham Woan (University of Glasgow) | Binary system delays and timing noise in searches for gravitational
waves from known pulsars | 10 pages, 11 figures, accepted by Phys. Rev. D | Phys.Rev.D76:042006,2007 | 10.1103/PhysRevD.76.042006 | LIGO-P060063-02-Z | gr-qc astro-ph | null | The majority of fast millisecond pulsars are in binary systems, so that any
periodic signal they emit is modulated by both Doppler and relativistic
effects. Here we show how well-established binary models can be used to account
for these effects in searches for gravitational waves from known pulsars within
binary systems. A seperate issue affecting certain pulsar signals is that of
timing noise and we show how this, with particular reference to the Crab
pulsar, can be compensated for by using regularly updated timing ephemerides.
| [
{
"created": "Fri, 30 Mar 2007 10:58:12 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Jun 2007 09:30:08 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Pitkin",
"Matthew",
"",
"University of Glasgow"
],
[
"Woan",
"Graham",
"",
"University of Glasgow"
]
] | The majority of fast millisecond pulsars are in binary systems, so that any periodic signal they emit is modulated by both Doppler and relativistic effects. Here we show how well-established binary models can be used to account for these effects in searches for gravitational waves from known pulsars within binary systems. A seperate issue affecting certain pulsar signals is that of timing noise and we show how this, with particular reference to the Crab pulsar, can be compensated for by using regularly updated timing ephemerides. |
1709.09501 | Charles Board | Charles V. R. Board and John D. Barrow | Cosmological Models in Energy-Momentum-Squared Gravity | Accepted manuscript, incorporates erratum | Phys. Rev. D 96, 123517 (2017) | 10.1103/PhysRevD.96.123517 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the cosmological effects of adding terms of higher-order in the
usual energy-momentum tensor to the matter lagrangian of general relativity.
This is in contrast to most studies of higher-order gravity which focus on
generalising the Einstein-Hilbert curvature contribution to the lagrangian. The
resulting cosmological theories include many particular theories, like bulk
viscous cosmologies, loop quantum gravity, K-essence, and brane-world
cosmologies. We find a range of exact solutions for isotropic universes,
discuss their behaviours with reference to the early and late-time evolution,
accelerated expansion, and the occurrence or avoidance of singularities. We
briefly discuss extensions to anisotropic cosmologies and delineate the
situations where the higher-order matter terms will dominate over anisotropies
on approach to cosmological singularities.
| [
{
"created": "Wed, 27 Sep 2017 13:32:50 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Sep 2017 14:04:17 GMT",
"version": "v2"
},
{
"created": "Wed, 10 Jan 2018 11:31:11 GMT",
"version": "v3"
},
{
"created": "Mon, 15 Apr 2019 13:28:21 GMT",
"version": "v4"
}
] | 2019-04-16 | [
[
"Board",
"Charles V. R.",
""
],
[
"Barrow",
"John D.",
""
]
] | We study the cosmological effects of adding terms of higher-order in the usual energy-momentum tensor to the matter lagrangian of general relativity. This is in contrast to most studies of higher-order gravity which focus on generalising the Einstein-Hilbert curvature contribution to the lagrangian. The resulting cosmological theories include many particular theories, like bulk viscous cosmologies, loop quantum gravity, K-essence, and brane-world cosmologies. We find a range of exact solutions for isotropic universes, discuss their behaviours with reference to the early and late-time evolution, accelerated expansion, and the occurrence or avoidance of singularities. We briefly discuss extensions to anisotropic cosmologies and delineate the situations where the higher-order matter terms will dominate over anisotropies on approach to cosmological singularities. |
1710.03794 | Maximiliano Isi | Maximiliano Isi and Alan J. Weinstein | Probing gravitational wave polarizations with signals from compact
binary coalescences | Technical note | null | null | LIGO-P1700276 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this technical note, we study the possibility of using networks of
ground-based detectors to directly measure gravitational-wave polarizations
using signals from compact binary coalescences. We present a simple data
analysis method to partially achieve this, assuming presence of a strong signal
well-captured by a GR template.
| [
{
"created": "Tue, 10 Oct 2017 19:26:39 GMT",
"version": "v1"
}
] | 2017-10-12 | [
[
"Isi",
"Maximiliano",
""
],
[
"Weinstein",
"Alan J.",
""
]
] | In this technical note, we study the possibility of using networks of ground-based detectors to directly measure gravitational-wave polarizations using signals from compact binary coalescences. We present a simple data analysis method to partially achieve this, assuming presence of a strong signal well-captured by a GR template. |
1710.02156 | Emanuele Berti | Vishal Baibhav, Emanuele Berti, Vitor Cardoso, Gaurav Khanna | Black Hole Spectroscopy: Systematic Errors and Ringdown Energy Estimates | 7 pages, 5 figures, 1 table | Phys. Rev. D 97, 044048 (2018) | 10.1103/PhysRevD.97.044048 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The relaxation of a distorted black hole to its final state provides
important tests of general relativity within the reach of current and upcoming
gravitational wave facilities. In black hole perturbation theory, this phase
consists of a simple linear superposition of exponentially damped sinusoids
(the quasinormal modes) and of a power-law tail. How many quasinormal modes are
necessary to describe waveforms with a prescribed precision? What error do we
incur by only including quasinormal modes, and not tails? What other systematic
effects are present in current state-of-the-art numerical waveforms? These
issues, which are basic to testing fundamental physics with distorted black
holes, have hardly been addressed in the literature. We use numerical
relativity waveforms and accurate evolutions within black hole perturbation
theory to provide some answers. We show that (i) a determination of the
fundamental $l=m=2$ quasinormal mode to within $1\%$ or better requires the
inclusion of at least the first overtone, and preferably of the first two or
three overtones; (ii) a determination of the black hole mass and spin with
precision better than $1\%$ requires the inclusion of at least two quasinormal
modes for any given angular harmonic mode $(\ell,\,m)$. We also improve on
previous estimates and fits for the ringdown energy radiated in the various
multipoles. These results are important to quantify theoretical (as opposed to
instrumental) limits in parameter estimation accuracy and tests of general
relativity allowed by ringdown measurements with high signal-to-noise ratio
gravitational wave detectors.
| [
{
"created": "Thu, 5 Oct 2017 18:00:16 GMT",
"version": "v1"
}
] | 2018-03-07 | [
[
"Baibhav",
"Vishal",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Khanna",
"Gaurav",
""
]
] | The relaxation of a distorted black hole to its final state provides important tests of general relativity within the reach of current and upcoming gravitational wave facilities. In black hole perturbation theory, this phase consists of a simple linear superposition of exponentially damped sinusoids (the quasinormal modes) and of a power-law tail. How many quasinormal modes are necessary to describe waveforms with a prescribed precision? What error do we incur by only including quasinormal modes, and not tails? What other systematic effects are present in current state-of-the-art numerical waveforms? These issues, which are basic to testing fundamental physics with distorted black holes, have hardly been addressed in the literature. We use numerical relativity waveforms and accurate evolutions within black hole perturbation theory to provide some answers. We show that (i) a determination of the fundamental $l=m=2$ quasinormal mode to within $1\%$ or better requires the inclusion of at least the first overtone, and preferably of the first two or three overtones; (ii) a determination of the black hole mass and spin with precision better than $1\%$ requires the inclusion of at least two quasinormal modes for any given angular harmonic mode $(\ell,\,m)$. We also improve on previous estimates and fits for the ringdown energy radiated in the various multipoles. These results are important to quantify theoretical (as opposed to instrumental) limits in parameter estimation accuracy and tests of general relativity allowed by ringdown measurements with high signal-to-noise ratio gravitational wave detectors. |
1905.04268 | J\'er\'emy Auffinger | Alexandre Arbey, J\'er\'emy Auffinger | BlackHawk v2.0: A public code for calculating the Hawking evaporation
spectra of any black hole distribution | 44 pages. BlackHawk v2.0 can be obtained at
https://blackhawk.hepforge.org/ | Eur.Phys.J. C79 (2019) no.8, 693 | 10.1140/epjc/s10052-019-7161-1 | CERN-TH-2019-067 | gr-qc astro-ph.CO astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe BlackHawk, a public C program for calculating the Hawking
evaporation spectra of any black hole distribution. This program allows the
users to compute the primary and secondary spectra of stable or long-lived
particles generated by Hawking radiation of the distribution of black holes,
and to study their evolution in time. The physics of Hawking radiation is
presented, and the capabilities, features and usage of BlackHawk are described
here under the form of a manual. This is the BlackHawk v2.0 manual, which is
available on the BlackHawk webpage http://blackhawk.hepforge.org/. A brief
release note summarizing the new aspects of BlackHawk v2.0 as well as
illustrating examples can be found in https://arxiv.org/abs/2108.02737.
| [
{
"created": "Fri, 10 May 2019 17:17:25 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Jan 2020 10:15:35 GMT",
"version": "v2"
},
{
"created": "Fri, 6 Aug 2021 09:39:36 GMT",
"version": "v3"
}
] | 2021-08-09 | [
[
"Arbey",
"Alexandre",
""
],
[
"Auffinger",
"Jérémy",
""
]
] | We describe BlackHawk, a public C program for calculating the Hawking evaporation spectra of any black hole distribution. This program allows the users to compute the primary and secondary spectra of stable or long-lived particles generated by Hawking radiation of the distribution of black holes, and to study their evolution in time. The physics of Hawking radiation is presented, and the capabilities, features and usage of BlackHawk are described here under the form of a manual. This is the BlackHawk v2.0 manual, which is available on the BlackHawk webpage http://blackhawk.hepforge.org/. A brief release note summarizing the new aspects of BlackHawk v2.0 as well as illustrating examples can be found in https://arxiv.org/abs/2108.02737. |
1804.10374 | Alexander Zakharov | Alexander F. Zakharov | Constraints on tidal charge of the supermassive black hole at the
Galactic Center with trajectories of bright stars | 9 pages, references were added, minor typos were corrected | null | 10.1140/epjc/s10052-018-6166-5 | null | gr-qc astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | As it was pointed out recently in Hees et al. (2017), observations of stars
near the Galactic Center with current and future facilities provide an unique
tool to test general relativity (GR) and alternative theories of gravity in a
strong gravitational field regime. In particular, the authors showed that the
Yukawa gravity could be constrained with Keck and TMT observations. Some time
ago, Dadhich et al. (2001) showed that the Reissner -- Nordstr\"om metric with
a tidal charge is naturally appeared in the framework of Randall -- Sundrum
model with an extra dimension ($Q^2$ is called tidal charge and it could be
negative in such an approach). Astrophysical consequences of of presence of
black holes with a tidal charge are considerered, in particular, geodesics and
shadows in Kerr -- Newman braneworld metric are analyzed in (Schee and
Stuchlik, 2009a), while profiles of emission lines generated by rings orbiting
braneworld Kerr black hole are considered in (Schee and Stuchlik, 2009b).
Possible observational signatures of gravitational lensing in a presence of the
Reissner -- Nordstr\"om black hole with a tidal charge at the Galactic Center
are discussed in papers by Bin-Nun (2010a, 2010b, 2011). Here we are following
such an approach and we obtain analytical expressions for orbital precession
for Reissner -- Nordstrom -- de-Sitter solution in post-Newtonian approximation
and discuss opportunities to constrain parameters of the metric from
observations of bright stars with current and future astrometric observational
facilities such as VLT, Keck, GRAVITY, E-ELT and TMT.
| [
{
"created": "Fri, 27 Apr 2018 08:03:50 GMT",
"version": "v1"
},
{
"created": "Sat, 5 May 2018 03:42:48 GMT",
"version": "v2"
},
{
"created": "Tue, 8 May 2018 15:59:46 GMT",
"version": "v3"
},
{
"created": "Mon, 25 Jun 2018 13:29:55 GMT",
"version": "v4"
},
{
"created": "Thu, 16 Aug 2018 10:55:32 GMT",
"version": "v5"
}
] | 2018-09-26 | [
[
"Zakharov",
"Alexander F.",
""
]
] | As it was pointed out recently in Hees et al. (2017), observations of stars near the Galactic Center with current and future facilities provide an unique tool to test general relativity (GR) and alternative theories of gravity in a strong gravitational field regime. In particular, the authors showed that the Yukawa gravity could be constrained with Keck and TMT observations. Some time ago, Dadhich et al. (2001) showed that the Reissner -- Nordstr\"om metric with a tidal charge is naturally appeared in the framework of Randall -- Sundrum model with an extra dimension ($Q^2$ is called tidal charge and it could be negative in such an approach). Astrophysical consequences of of presence of black holes with a tidal charge are considerered, in particular, geodesics and shadows in Kerr -- Newman braneworld metric are analyzed in (Schee and Stuchlik, 2009a), while profiles of emission lines generated by rings orbiting braneworld Kerr black hole are considered in (Schee and Stuchlik, 2009b). Possible observational signatures of gravitational lensing in a presence of the Reissner -- Nordstr\"om black hole with a tidal charge at the Galactic Center are discussed in papers by Bin-Nun (2010a, 2010b, 2011). Here we are following such an approach and we obtain analytical expressions for orbital precession for Reissner -- Nordstrom -- de-Sitter solution in post-Newtonian approximation and discuss opportunities to constrain parameters of the metric from observations of bright stars with current and future astrometric observational facilities such as VLT, Keck, GRAVITY, E-ELT and TMT. |
0904.3276 | Frans Klinkhamer | F.R. Klinkhamer | Gluon condensate, modified gravity, and the accelerating Universe | 24 pages in preprint style; v6: published version | Phys.Rev.D81:043006,2010 | 10.1103/PhysRevD.81.043006 | KA-TP-02-2009 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been suggested recently to study the dynamics of a gravitating gluon
condensate q in the context of a spatially flat Friedmann-Robertson-Walker
universe. The expansion of the Universe (or, more generally, the presence of a
nonvanishing Ricci curvature scalar R) perturbs the gluon condensate and may
induce a nonanalytic term \tilde{h}(R,q) in the effective gravitational action.
The aim of this article is to explore the cosmological implications of a
particular nonanalytic term \tilde{h} \propto \eta |R|^{1/2} |q|^{3/4}. With a
quadratic approximation of the gravitating gluon-condensate vacuum energy
density \rho_{V}(q) near the equilibrium value q_{0} and a small coupling
constant \eta of the modified-gravity term \tilde{h}, an "accelerating
universe" is obtained which resembles the present Universe, both qualitatively
and quantitatively. The unknown component X of this model universe (here,
primarily due to modified-gravity effects) has an effective equation-of-state
parameter \bar{w}_{X} which is found to evolve toward the value -1 from above.
| [
{
"created": "Tue, 21 Apr 2009 19:05:10 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Apr 2009 09:33:44 GMT",
"version": "v2"
},
{
"created": "Mon, 4 May 2009 18:55:46 GMT",
"version": "v3"
},
{
"created": "Sat, 27 Jun 2009 13:26:14 GMT",
"version": "v4"
},
{
"created": "Tue, 26 Jan 2010 12:36:20 GMT",
"version": "v5"
},
{
"created": "Wed, 10 Feb 2010 19:02:03 GMT",
"version": "v6"
}
] | 2010-04-06 | [
[
"Klinkhamer",
"F. R.",
""
]
] | It has been suggested recently to study the dynamics of a gravitating gluon condensate q in the context of a spatially flat Friedmann-Robertson-Walker universe. The expansion of the Universe (or, more generally, the presence of a nonvanishing Ricci curvature scalar R) perturbs the gluon condensate and may induce a nonanalytic term \tilde{h}(R,q) in the effective gravitational action. The aim of this article is to explore the cosmological implications of a particular nonanalytic term \tilde{h} \propto \eta |R|^{1/2} |q|^{3/4}. With a quadratic approximation of the gravitating gluon-condensate vacuum energy density \rho_{V}(q) near the equilibrium value q_{0} and a small coupling constant \eta of the modified-gravity term \tilde{h}, an "accelerating universe" is obtained which resembles the present Universe, both qualitatively and quantitatively. The unknown component X of this model universe (here, primarily due to modified-gravity effects) has an effective equation-of-state parameter \bar{w}_{X} which is found to evolve toward the value -1 from above. |
1912.12298 | Alexander Gallego Cadavid Dr | Alexander Gallego Cadavid and J.R. Villanueva | No slow-roll inflation \`a la Generalized Chaplygin Gas in General
Relativity | Accepted for publication in JCAP. 19 pages. 9 figures | JCAP12(2020)044 | 10.1088/1475-7516/2020/12/044 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Generalized Chaplygin Gas (GCG) model is characterized by the equation of
state $P = -A \rho^{-\alpha}$, where $A>0$ and $\alpha < 1$. The model has been
extensively studied due to its interesting properties and applicability in
several contexts, from late-time acceleration to primordial inflation.
Nonetheless we show that the inflationary slow-roll regime cannot be satisfied
by most of the parameter space of the GCG model when General Relativity (GR) is
considered. In particular, although the model has been applied to inflation
with $0 < \alpha < 1$, we show that for $-1 < \alpha \le 1$ there is no
expansion of the Universe but an accelerated contraction. For $\alpha \le
-5/3$, the second slow-roll parameter $\eta_H$ is larger than unity, so there
is no sustained period of inflation. Only for $\alpha$ very close to -1 the
model produces enough $e$-folds, thus greatly reducing its parameter space.
Moreover, we show that the model is ruled out by the Planck 2018 results.
Finally, we extend our analysis to the Generalized Chaplygin-Jacobi Gas (GCJG)
model. We find that the introduction of a new parameter does not change the
previous results. We thus conclude that the violation of the slow-roll
conditions is a generic feature of the GCG and GCJG models during inflation
when GR is considered and that the models are ruled out by the Planck 2018
results.
| [
{
"created": "Thu, 26 Dec 2019 20:34:32 GMT",
"version": "v1"
},
{
"created": "Tue, 26 May 2020 21:21:57 GMT",
"version": "v2"
},
{
"created": "Mon, 20 Jul 2020 21:18:21 GMT",
"version": "v3"
},
{
"created": "Wed, 4 Nov 2020 20:07:46 GMT",
"version": "v4"
}
] | 2021-01-01 | [
[
"Cadavid",
"Alexander Gallego",
""
],
[
"Villanueva",
"J. R.",
""
]
] | The Generalized Chaplygin Gas (GCG) model is characterized by the equation of state $P = -A \rho^{-\alpha}$, where $A>0$ and $\alpha < 1$. The model has been extensively studied due to its interesting properties and applicability in several contexts, from late-time acceleration to primordial inflation. Nonetheless we show that the inflationary slow-roll regime cannot be satisfied by most of the parameter space of the GCG model when General Relativity (GR) is considered. In particular, although the model has been applied to inflation with $0 < \alpha < 1$, we show that for $-1 < \alpha \le 1$ there is no expansion of the Universe but an accelerated contraction. For $\alpha \le -5/3$, the second slow-roll parameter $\eta_H$ is larger than unity, so there is no sustained period of inflation. Only for $\alpha$ very close to -1 the model produces enough $e$-folds, thus greatly reducing its parameter space. Moreover, we show that the model is ruled out by the Planck 2018 results. Finally, we extend our analysis to the Generalized Chaplygin-Jacobi Gas (GCJG) model. We find that the introduction of a new parameter does not change the previous results. We thus conclude that the violation of the slow-roll conditions is a generic feature of the GCG and GCJG models during inflation when GR is considered and that the models are ruled out by the Planck 2018 results. |
gr-qc/0002095 | Carlo Rovelli | Michael P. Reisenberger, Carlo Rovelli | Spacetime as a Feynman diagram: the connection formulation | 32 pages, 2 figures | Class.Quant.Grav. 18 (2001) 121-140 | 10.1088/0264-9381/18/1/308 | null | gr-qc hep-th | null | Spin foam models are the path integral counterparts to loop quantized
canonical theories. In the last few years several spin foam models of gravity
have been proposed, most of which live on finite simplicial lattice spacetime.
The lattice truncates the presumably infinite set of gravitational degrees of
freedom down to a finite set. Models that can accomodate an infinite set of
degrees of freedom and that are independent of any background simplicial
structure, or indeed any a priori spacetime topology, can be obtained from the
lattice models by summing them over all lattice spacetimes. Here we show that
this sum can be realized as the sum over Feynman diagrams of a quantum field
theory living on a suitable group manifold, with each Feynman diagram defining
a particular lattice spacetime. We give an explicit formula for the action of
the field theory corresponding to any given spin foam model in a wide class
which includes several gravity models. Such a field theory was recently found
for a particular gravity model [De Pietri et al, hep-th/9907154]. Our work
generalizes this result as well as Boulatov's and Ooguri's models of three and
four dimensional topological field theories, and ultimately the old matrix
models of two dimensional systems with dynamical topology. A first version of
our result has appeared in a companion paper [gr-qc\0002083]: here we present a
new and more detailed derivation based on the connection formulation of the
spin foam models.
| [
{
"created": "Tue, 29 Feb 2000 14:45:32 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Mar 2000 11:05:36 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Reisenberger",
"Michael P.",
""
],
[
"Rovelli",
"Carlo",
""
]
] | Spin foam models are the path integral counterparts to loop quantized canonical theories. In the last few years several spin foam models of gravity have been proposed, most of which live on finite simplicial lattice spacetime. The lattice truncates the presumably infinite set of gravitational degrees of freedom down to a finite set. Models that can accomodate an infinite set of degrees of freedom and that are independent of any background simplicial structure, or indeed any a priori spacetime topology, can be obtained from the lattice models by summing them over all lattice spacetimes. Here we show that this sum can be realized as the sum over Feynman diagrams of a quantum field theory living on a suitable group manifold, with each Feynman diagram defining a particular lattice spacetime. We give an explicit formula for the action of the field theory corresponding to any given spin foam model in a wide class which includes several gravity models. Such a field theory was recently found for a particular gravity model [De Pietri et al, hep-th/9907154]. Our work generalizes this result as well as Boulatov's and Ooguri's models of three and four dimensional topological field theories, and ultimately the old matrix models of two dimensional systems with dynamical topology. A first version of our result has appeared in a companion paper [gr-qc\0002083]: here we present a new and more detailed derivation based on the connection formulation of the spin foam models. |
1402.2384 | Daniele Pranzetti | Daniele Pranzetti | Turaev-Viro amplitudes from 2+1 Loop Quantum Gravity | 23 pages, many figures; v3: minor modifications to match published
version | Phys. Rev. D 89, 084058 (2014) | 10.1103/PhysRevD.89.084058 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Turaev-Viro state sum model provides a covariant spin foam quantization
of three-dimensional Riemannian gravity with a positive cosmological constant
{\Lambda}. We complete the program to canonically quantize the theory in the BF
formulation using the formalism of Loop Quantum Gravity. In particular, we show
first how quantum group structures arise from the requirement of the constraint
algebra to be anomaly free. This allows us to generalize the construction of
the physical scalar product, from the {\Lambda} = 0 case, in presence of a
positive {\Lambda}. We prove the equivalence between the covariant and
canonical quantizations by recovering the spin foam amplitudes.
| [
{
"created": "Tue, 11 Feb 2014 07:04:08 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Feb 2014 17:19:38 GMT",
"version": "v2"
},
{
"created": "Tue, 22 Apr 2014 07:43:16 GMT",
"version": "v3"
}
] | 2014-04-23 | [
[
"Pranzetti",
"Daniele",
""
]
] | The Turaev-Viro state sum model provides a covariant spin foam quantization of three-dimensional Riemannian gravity with a positive cosmological constant {\Lambda}. We complete the program to canonically quantize the theory in the BF formulation using the formalism of Loop Quantum Gravity. In particular, we show first how quantum group structures arise from the requirement of the constraint algebra to be anomaly free. This allows us to generalize the construction of the physical scalar product, from the {\Lambda} = 0 case, in presence of a positive {\Lambda}. We prove the equivalence between the covariant and canonical quantizations by recovering the spin foam amplitudes. |
2301.02109 | Orfeu Bertolami | Orfeu Bertolami, Cl\'audio Gomes, Paulo M. S\'a | Theories of gravity with nonminimal matter-curvature coupling and the de
Sitter swampland conjectures | 12 pages | null | 10.1103/PhysRevD.107.084009 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | We discuss, in the context of alternative theories of gravity with nonminimal
coupling between matter and curvature, if inflationary solutions driven by a
single scalar field can be reconciled with the swampland conjectures about the
emergence of de Sitter solutions in string theory. We find that the slow-roll
conditions are incompatible with the swampland conjectures for a fairly generic
inflationary solution in such alternative theories of gravity.
| [
{
"created": "Thu, 5 Jan 2023 15:32:49 GMT",
"version": "v1"
}
] | 2023-04-19 | [
[
"Bertolami",
"Orfeu",
""
],
[
"Gomes",
"Cláudio",
""
],
[
"Sá",
"Paulo M.",
""
]
] | We discuss, in the context of alternative theories of gravity with nonminimal coupling between matter and curvature, if inflationary solutions driven by a single scalar field can be reconciled with the swampland conjectures about the emergence of de Sitter solutions in string theory. We find that the slow-roll conditions are incompatible with the swampland conjectures for a fairly generic inflationary solution in such alternative theories of gravity. |
1903.10351 | Mario Novello | M. Novello and A. E. S. Hartmann | Is the electromagnetic field responsible for the cosmic acceleration in
late times? | In this paper we present a new way to describe the origin of the
cosmological era of accelerated expansion. We show that such acceleration may
be associated to a late effect of the non minimal coupling between the
electromagnetic field with gravity in the realm of general relativity | null | 10.1142/S0217751X19500830 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that in the realm of general relativity a non minimal coupling
between the electromagnetic and the gravitational fields may produce an era of
accelerated expansion.
| [
{
"created": "Fri, 22 Mar 2019 13:20:29 GMT",
"version": "v1"
}
] | 2019-06-26 | [
[
"Novello",
"M.",
""
],
[
"Hartmann",
"A. E. S.",
""
]
] | We show that in the realm of general relativity a non minimal coupling between the electromagnetic and the gravitational fields may produce an era of accelerated expansion. |
2402.17835 | Kieran Wood | Kieran Wood, Paul M. Saffin, Anastasios Avgoustidis | Black Holes in Multi-Metric Gravity | 27 pages, no figures. Current version: fixed typos, added DOI | null | 10.1103/PhysRevD.109.124006 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We construct a wide class of black hole solutions to the general theory of
ghost free multi-metric gravity in arbitrary spacetime dimension, extending and
generalising the known results in 4-dimensional dRGT massive gravity and
bigravity. The solutions are split into three generic classes based on whether
the metrics can be simultaneously diagonalised - one of which does not exist in
dRGT massive gravity nor bigravity, and is only possible when one has more than
two interacting metric fields. We also linearise the general multi-metric
theory to determine the dynamics of the massive spin-2 modes, including
examples where this can be done analytically, and use the linear theory to
discuss the stability of the 4-dimensional multi-Schwarzchild and multi-Kerr
solutions. We explain how the instabilities that plague these solutions in dRGT
massive gravity and bigravity carry across to the general multi-metric theory,
touching upon ideas of dimensional deconstruction to make sense of the results.
| [
{
"created": "Tue, 27 Feb 2024 19:00:09 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Jun 2024 16:35:04 GMT",
"version": "v2"
}
] | 2024-06-05 | [
[
"Wood",
"Kieran",
""
],
[
"Saffin",
"Paul M.",
""
],
[
"Avgoustidis",
"Anastasios",
""
]
] | We construct a wide class of black hole solutions to the general theory of ghost free multi-metric gravity in arbitrary spacetime dimension, extending and generalising the known results in 4-dimensional dRGT massive gravity and bigravity. The solutions are split into three generic classes based on whether the metrics can be simultaneously diagonalised - one of which does not exist in dRGT massive gravity nor bigravity, and is only possible when one has more than two interacting metric fields. We also linearise the general multi-metric theory to determine the dynamics of the massive spin-2 modes, including examples where this can be done analytically, and use the linear theory to discuss the stability of the 4-dimensional multi-Schwarzchild and multi-Kerr solutions. We explain how the instabilities that plague these solutions in dRGT massive gravity and bigravity carry across to the general multi-metric theory, touching upon ideas of dimensional deconstruction to make sense of the results. |
1903.09913 | Xiangyun Fu fu | Xiangyun Fu, Lu Zhou and Jun Chen | Testing Cosmic Distance-Duality Relation from Future Gravitational Wave
Standard Sirens | Submitted to PRD 17pages,3figs | Phys. Rev. D 99, 083523 (2019) | 10.1103/PhysRevD.99.083523 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A validation of the cosmic distance-duality relation (CDDR) is crucial
because any observational departure from it could be a signal of new physics.
In this work, we explore the potentialities of luminosity distance data from
the gravitational wave (GW) standard sirens of future Einstein Telescope (ET)
to test the CDDR. The angular diameter distance data are used from the galaxy
clusters samples and the baryon acoustic oscillation (BAO) measurements. The
basic advantage of GW measurements substituting for the observations from the
type Ia supernovae (SNIa) is that the luminosity distance from it is
insensitive to the non-conservation of the number of photons. By simulating 550
and 1000 data points of future GW measurements in the low redshift range
$0<z<1$, we show that the measurements of future GW events will be a powerful
tool to test the CDDR.
| [
{
"created": "Sun, 24 Mar 2019 02:44:18 GMT",
"version": "v1"
}
] | 2019-05-01 | [
[
"Fu",
"Xiangyun",
""
],
[
"Zhou",
"Lu",
""
],
[
"Chen",
"Jun",
""
]
] | A validation of the cosmic distance-duality relation (CDDR) is crucial because any observational departure from it could be a signal of new physics. In this work, we explore the potentialities of luminosity distance data from the gravitational wave (GW) standard sirens of future Einstein Telescope (ET) to test the CDDR. The angular diameter distance data are used from the galaxy clusters samples and the baryon acoustic oscillation (BAO) measurements. The basic advantage of GW measurements substituting for the observations from the type Ia supernovae (SNIa) is that the luminosity distance from it is insensitive to the non-conservation of the number of photons. By simulating 550 and 1000 data points of future GW measurements in the low redshift range $0<z<1$, we show that the measurements of future GW events will be a powerful tool to test the CDDR. |
2305.04367 | Calin Iuliu Lazaroiu | Calin Iuliu Lazaroiu | Natural observables and dynamical approximations in multifield
cosmological models | 36 pages, 2 figures | Int. J. Modern Physics A. 38 (2023) 32, 2343007 | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | I give a geometric construction of certain first order natural dynamical
observables in multifield cosmological models with arbitrary target space
topology and discuss a system of related dynamical approximations and regimes
for such models.
| [
{
"created": "Sun, 7 May 2023 20:02:26 GMT",
"version": "v1"
}
] | 2024-07-09 | [
[
"Lazaroiu",
"Calin Iuliu",
""
]
] | I give a geometric construction of certain first order natural dynamical observables in multifield cosmological models with arbitrary target space topology and discuss a system of related dynamical approximations and regimes for such models. |
1402.4974 | Michal Bejger | J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T.
Accadia, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X.
Adhikari, C. Affeldt, M. Agathos, N. Aggarwal, O. D. Aguiar, A. Ain, P.
Ajith, A. Alemic, B. Allen, A. Allocca, D. Amariutei, M. Andersen, R.
Anderson, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux,
J. Areeda, S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert, L. Austin, B. E.
Aylott, S. Babak, P. T. Baker, G. Ballardin, S. W. Ballmer, J. C. Barayoga,
M. Barbet, B. C. Barish, D. Barker, F. Barone, B. Barr, L. Barsotti, M.
Barsuglia, M. A. Barton, I. Bartos, R. Bassiri, A. Basti, J. C. Batch, J.
Bauchrowitz, Th. S. Bauer, B. Behnke, M. Bejger, M. G. Beker, C. Belczynski,
A. S. Bell, C. Bell, G. Bergmann, D. Bersanetti, A. Bertolini, J. Betzwieser,
P. T. Beyersdorf, I. A. Bilenko, G. Billingsley, J. Birch, S. Biscans, M.
Bitossi, M. A. Bizouard, E. Black, J. K. Blackburn, L. Blackburn, D. Blair,
S. Bloemen, M. Blom, O. Bock, T. P. Bodiya, M. Boer, G. Bogaert, C. Bogan, C.
Bond, F. Bondu, L. Bonelli, R. Bonnand, R. Bork, M. Born, K. Borkowski, V.
Boschi, Sukanta Bose, L. Bosi, C. Bradaschia, P. R. Brady, V. B. Braginsky,
M. Branchesi, J. E. Brau, T. Briant, D. O. Bridges, A. Brillet, M. Brinkmann,
V. Brisson, A. F. Brooks, D. A. Brown, D. D. Brown, F. Br\"uckner, S.
Buchman, T. Bulik, H. J. Bulten, A. Buonanno, R. Burman, D. Buskulic, C. Buy,
L. Cadonati, G. Cagnoli, J. Calder\'on Bustillo, E. Calloni, J. B. Camp, P.
Campsie, K. C. Cannon, B. Canuel, J. Cao, C. D. Capano, F. Carbognani, L.
Carbone, S. Caride, A. Castiglia, S. Caudill, M. Cavagli\`a, F. Cavalier, R.
Cavalieri, C. Celerier, G. Cella, C. Cepeda, E. Cesarini, R. Chakraborty, T.
Chalermsongsak, S. J. Chamberlin, S. Chao, P. Charlton, E. Chassande-Mottin,
X. Chen, Y. Chen, A. Chincarini, A. Chiummo, H. S. Cho, J. Chow, N.
Christensen, Q. Chu, S. S. Y. Chua, S. Chung, G. Ciani, F. Clara, J. A.
Clark, F. Cleva, E. Coccia, P.-F. Cohadon, A. Colla, C. Collette, M.
Colombini, L. Cominsky, M. Constancio Jr., A. Conte, D. Cook, T. R. Corbitt,
M. Cordier, N. Cornish, A. Corpuz, A. Corsi, C. A. Costa, M. W. Coughlin, S.
Coughlin, J.-P. Coulon, S. Countryman, P. Couvares, D. M. Coward, M. Cowart,
D. C. Coyne, R. Coyne, K. Craig, J. D. E. Creighton, S. G. Crowder, A.
Cumming, L. Cunningham, E. Cuoco, K. Dahl, T. Dal Canton, M. Damjanic, S. L.
Danilishin, S. D'Antonio, K. Danzmann, V. Dattilo, H. Daveloza, M. Davier, G.
S. Davies, E. J. Daw, R. Day, T. Dayanga, G. Debreczeni, J. Degallaix, S.
Del\'eglise, W. Del Pozzo, T. Denker, T. Dent, H. Dereli, V. Dergachev, R. De
Rosa, R. T. DeRosa, R. DeSalvo, S. Dhurandhar, M. D\'iaz, L. Di Fiore, A. Di
Lieto, I. Di Palma, A. Di Virgilio, A. Donath, F. Donovan, K. L. Dooley, S.
Doravari, O. Dorosh, S. Dossa, R. Douglas, T. P. Downes, M. Drago, R. W. P.
Drever, J. C. Driggers, Z. Du, S. Dwyer, T. Eberle, T. Edo, M. Edwards, A.
Effler, H. Eggenstein, P. Ehrens, J. Eichholz, S. S. Eikenberry, G.
Endr\H{o}czi, R. Essick, T. Etzel, M. Evans, T. Evans, M. Factourovich, V.
Fafone, S. Fairhurst, Q. Fang, S. Farinon, B. Farr, W. M. Farr, M. Favata, H.
Fehrmann, M. M. Fejer, D. Feldbaum, F. Feroz, I. Ferrante, F. Ferrini, F.
Fidecaro, L. S. Finn, I. Fiori, R. P. Fisher, R. Flaminio, J.-D. Fournier, S.
Franco, S. Frasca, F. Frasconi, M. Frede, Z. Frei, A. Freise, R. Frey, T. T.
Fricke, P. Fritschel, V. V. Frolov, P. Fulda, M. Fyffe, J. Gair, L.
Gammaitoni, S. Gaonkar, F. Garufi, N. Gehrels, G. Gemme, E. Genin, A. Gennai,
S. Ghosh, J. A. Giaime, K. D. Giardina, A. Giazotto, C. Gill, J. Gleason, E.
Goetz, R. Goetz, L. Gondan, G. Gonz\'alez, N. Gordon, M. L. Gorodetsky, S.
Gossan, S. Go{\ss}ler, R. Gouaty, C. Gr\"af, P. B. Graff, M. Granata, A.
Grant, S. Gras, C. Gray, R. J. S. Greenhalgh, A. M. Gretarsson, P. Groot, H.
Grote, K. Grover, S. Grunewald, G. M. Guidi, C. Guido, K. Gushwa, E. K.
Gustafson, R. Gustafson, D. Hammer, G. Hammond, M. Hanke, J. Hanks, C. Hanna,
J. Hanson, J. Harms, G. M. Harry, I. W. Harry, E. D. Harstad, M. Hart, M. T.
Hartman, C.-J. Haster, K. Haughian, A. Heidmann, M. Heintze, H. Heitmann, P.
Hello, G. Hemming, M. Hendry, I. S. Heng, A. W. Heptonstall, M. Heurs, M.
Hewitson, S. Hild, D. Hoak, K. A. Hodge, K. Holt, S. Hooper, P. Hopkins, D.
J. Hosken, J. Hough, E. J. Howell, Y. Hu, E. Huerta, B. Hughey, S. Husa, S.
H. Huttner, M. Huynh, T. Huynh-Dinh, D. R. Ingram, R. Inta, T. Isogai, A.
Ivanov, B. R. Iyer, K. Izumi, M. Jacobson, E. James, H. Jang, P. Jaranowski,
Y. Ji, F. Jim\'enez-Forteza, W. W. Johnson, D. I. Jones, R. Jones, R.J.G.
Jonker, L. Ju, Haris K, P. Kalmus, V. Kalogera, S. Kandhasamy, G. Kang, J. B.
Kanner, J. Karlen, M. Kasprzack, E. Katsavounidis, W. Katzman, H. Kaufer, K.
Kawabe, F. Kawazoe, F. K\'ef\'elian, G. M. Keiser, D. Keitel, D. B. Kelley,
W. Kells, A. Khalaidovski, F. Y. Khalili, E. A. Khazanov, C. Kim, K. Kim, N.
Kim, N. G. Kim, Y.-M. Kim, E. J. King, P. J. King, D. L. Kinzel, J. S.
Kissel, S. Klimenko, J. Kline, S. Koehlenbeck, K. Kokeyama, V. Kondrashov, S.
Koranda, W. Z. Korth, I. Kowalska, D. B. Kozak, A. Kremin, V. Kringel, B.
Krishnan, A. Kr\'olak, G. Kuehn, A. Kumar, P. Kumar, R. Kumar, L. Kuo, A.
Kutynia, P. Kwee, M. Landry, B. Lantz, S. Larson, P. D. Lasky, C. Lawrie, A.
Lazzarini, C. Lazzaro, P. Leaci, S. Leavey, E. O. Lebigot, C.-H. Lee, H. K.
Lee, H. M. Lee, J. Lee, M. Leonardi, J. R. Leong, A. Le Roux, N. Leroy, N.
Letendre, Y. Levin, B. Levine, J. Lewis, T. G. F. Li, K. Libbrecht, A.
Libson, A. C. Lin, T. B. Littenberg, V. Litvine, N. A. Lockerbie, V. Lockett,
D. Lodhia, K. Loew, J. Logue, A. L. Lombardi, M. Lorenzini, V. Loriette, M.
Lormand, G. Losurdo, J. Lough, M. J. Lubinski, H. L\"uck, E. Luijten, A. P.
Lundgren, R. Lynch, Y. Ma, J. Macarthur, E. P. Macdonald, T. MacDonald, B.
Machenschalk, M. MacInnis, D. M. Macleod, F. Magana-Sandoval, M. Mageswaran,
C. Maglione, K. Mailand, E. Majorana, I. Maksimovic, V. Malvezzi, N. Man, G.
M. Manca, I. Mandel, V. Mandic, V. Mangano, N. Mangini, M. Mantovani, F.
Marchesoni, F. Marion, S. M\'arka, Z. M\'arka, A. Markosyan, E. Maros, J.
Marque, F. Martelli, I. W. Martin, R. M. Martin, L. Martinelli, D. Martynov,
J. N. Marx, K. Mason, A. Masserot, T. J. Massinger, F. Matichard, L. Matone,
R. A. Matzner, N. Mavalvala, N. Mazumder, G. Mazzolo, R. McCarthy, D. E.
McClelland, S. C. McGuire, G. McIntyre, J. McIver, K. McLin, D. Meacher, G.
D. Meadors, M. Mehmet, J. Meidam, M. Meinders, A. Melatos, G. Mendell, R. A.
Mercer, S. Meshkov, C. Messenger, P. Meyers, H. Miao, C. Michel, E. E.
Mikhailov, L. Milano, S. Milde, J. Miller, Y. Minenkov, C. M. F. Mingarelli,
C. Mishra, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, B. Moe,
P. Moesta, M. Mohan, S. R. P. Mohapatra, D. Moraru, G. Moreno, N. Morgado, S.
R. Morriss, K. Mossavi, B. Mours, C. M. Mow-Lowry, C. L. Mueller, G. Mueller,
S. Mukherjee, A. Mullavey, J. Munch, D. Murphy, P. G. Murray, A. Mytidis, M.
F. Nagy, D. Nanda Kumar, I. Nardecchia, L. Naticchioni, R. K. Nayak, V.
Necula, G. Nelemans, I. Neri, M. Neri, G. Newton, T. Nguyen, A. Nitz, F.
Nocera, D. Nolting, M. E. N. Normandin, L. K. Nuttall, E. Ochsner, J. O'Dell,
E. Oelker, J. J. Oh, S. H. Oh, F. Ohme, P. Oppermann, B. O'Reilly, R.
O'Shaughnessy, C. Osthelder, D. J. Ottaway, R. S. Ottens, H. Overmier, B. J.
Owen, C. Padilla, A. Pai, O. Palashov, C. Palomba, H. Pan, Y. Pan, C. Pankow,
F. Paoletti, R. Paoletti, M. A. Papa, H. Paris, A. Pasqualetti, R.
Passaquieti, D. Passuello, M. Pedraza, S. Penn, A. Perreca, M. Phelps, M.
Pichot, M. Pickenpack, F. Piergiovanni, V. Pierro, M. Pietka, L. Pinard, I.
M. Pinto, M. Pitkin, J. Poeld, R. Poggiani, A. Poteomkin, J. Powell, J.
Prasad, S. Premachandra, T. Prestegard, L. R. Price, M. Prijatelj, S.
Privitera, G. A. Prodi, L. Prokhorov, O. Puncken, M. Punturo, P. Puppo, J.
Qin, V. Quetschke, E. Quintero, G. Quiroga, R. Quitzow-James, F. J. Raab, D.
S. Rabeling, I. R\'acz, H. Radkins, P. Raffai, S. Raja, G. Rajalakshmi, M.
Rakhmanov, C. Ramet, K. Ramirez, P. Rapagnani, V. Raymond, V. Re, J. Read, C.
M. Reed, T. Regimbau, S. Reid, D. H. Reitze, E. Rhoades, F. Ricci, K. Riles,
N. A. Robertson, F. Robinet, A. Rocchi, M. Rodruck, L. Rolland, J. G.
Rollins, R. Romano, G. Romanov, J. H. Romie, D. Rosi\'nska, S. Rowan, A.
R\"udiger, P. Ruggi, K. Ryan, F. Salemi, L. Sammut, V. Sandberg, J. R.
Sanders, V. Sannibale, I. Santiago-Prieto, E. Saracco, B. Sassolas, B. S.
Sathyaprakash, P. R. Saulson, R. Savage, J. Scheuer, R. Schilling, R.
Schnabel, R. M. S. Schofield, E. Schreiber, D. Schuette, B. F. Schutz, J.
Scott, S. M. Scott, D. Sellers, A. S. Sengupta, D. Sentenac, V. Sequino, A.
Sergeev, D. Shaddock, S. Shah, M. S. Shahriar, M. Shaltev, B. Shapiro, P.
Shawhan, D. H. Shoemaker, T. L. Sidery, K. Siellez, X. Siemens, D. Sigg, D.
Simakov, A. Singer, L. Singer, R. Singh, A. M. Sintes, B. J. J. Slagmolen, J.
Slutsky, J. R. Smith, M. Smith, R. J. E. Smith, N. D. Smith-Lefebvre, E. J.
Son, B. Sorazu, T. Souradeep, L. Sperandio, A. Staley, J. Stebbins, J.
Steinlechner, S. Steinlechner, B. C. Stephens, S. Steplewski, S. Stevenson,
R. Stone, D. Stops, K. A. Strain, N. Straniero, S. Strigin, R. Sturani, A. L.
Stuver, T. Z. Summerscales, S. Susmithan, P. J. Sutton, B. Swinkels, M.
Tacca, D. Talukder, D. B. Tanner, S. P. Tarabrin, R. Taylor, A. P. M. ter
Braack, M. P. Thirugnanasambandam, M. Thomas, P. Thomas, K. A. Thorne, K. S.
Thorne, E. Thrane, V. Tiwari, K. V. Tokmakov, C. Tomlinson, A. Toncelli, M.
Tonelli, O. Torre, C. V. Torres, C. I. Torrie, F. Travasso, G. Traylor, M.
Tse, D. Ugolini, C. S. Unnikrishnan, A. L. Urban, K. Urbanek, H. Vahlbruch,
G. Vajente, G. Valdes, M. Vallisneri, J. F. J. van den Brand, C. Van Den
Broeck, S. van der Putten, M. V. van der Sluys, J. van Heijningen, A. A. van
Veggel, S. Vass, M. Vas\'uth, R. Vaulin, A. Vecchio, G. Vedovato, J. Veitch,
P. J. Veitch, K. Venkateswara, D. Verkindt, S. S. Verma, F. Vetrano, A.
Vicer\'e, R. Vincent-Finley, J.-Y. Vinet, S. Vitale, T. Vo, H. Vocca, C.
Vorvick, W. D. Vousden, S. P. Vyachanin, A. Wade, L. Wade, M. Wade, M.
Walker, L. Wallace, M. Wang, X. Wang, R. L. Ward, M. Was, B. Weaver, L.-W.
Wei, M. Weinert, A. J. Weinstein, R. Weiss, T. Welborn, L. Wen, P. Wessels,
M. West, T. Westphal, K. Wette, J. T. Whelan, D. J. White, B. F. Whiting, K.
Wiesner, C. Wilkinson, K. Williams, L. Williams, R. Williams, T. Williams, A.
R. Williamson, J. L. Willis, B. Willke, M. Wimmer, W. Winkler, C. C. Wipf, A.
G. Wiseman, H. Wittel, G. Woan, J. Worden, J. Yablon, I. Yakushin, H.
Yamamoto, C. C. Yancey, H. Yang, Z. Yang, S. Yoshida, M. Yvert, A.
Zadro\.zny, M. Zanolin, J.-P. Zendri, Fan Zhang, L. Zhang, C. Zhao, X. J.
Zhu, M. E. Zucker, S. Zuraw, J. Zweizig | Implementation of an F-statistic all-sky search for continuous
gravitational waves in Virgo VSR1 data | 27 pages, 10 figures, submitted to CQG, corrected affiliations and
autors list; Science summary of results available at
http://www.ligo.org/science/Publication-VSR1CWAllSkyFstat/index.php | null | 10.1088/0264-9381/31/16/165014 | LIGO Document No. LIGO-P1300133 | gr-qc astro-ph.HE astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an implementation of the $\mathcal{F}$-statistic to carry out the
first search in data from the Virgo laser interferometric gravitational wave
detector for periodic gravitational waves from a priori unknown, isolated
rotating neutron stars. We searched a frequency $f_0$ range from 100 Hz to 1
kHz and the frequency dependent spindown $f_1$ range from $-1.6\,(f_0/100\,{\rm
Hz}) \times 10^{-9}\,$ Hz/s to zero. A large part of this frequency - spindown
space was unexplored by any of the all-sky searches published so far. Our
method consisted of a coherent search over two-day periods using the
$\mathcal{F}$-statistic, followed by a search for coincidences among the
candidates from the two-day segments. We have introduced a number of novel
techniques and algorithms that allow the use of the Fast Fourier Transform
(FFT) algorithm in the coherent part of the search resulting in a fifty-fold
speed-up in computation of the $\mathcal{F}$-statistic with respect to the
algorithm used in the other pipelines. No significant gravitational wave signal
was found. The sensitivity of the search was estimated by injecting signals
into the data. In the most sensitive parts of the detector band more than 90%
of signals would have been detected with dimensionless gravitational-wave
amplitude greater than $5 \times 10^{-24}$.
| [
{
"created": "Thu, 20 Feb 2014 11:53:07 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Feb 2014 12:38:07 GMT",
"version": "v2"
},
{
"created": "Thu, 10 Apr 2014 09:20:50 GMT",
"version": "v3"
}
] | 2015-06-18 | [
[
"Aasi",
"J.",
""
],
[
"Abbott",
"B. P.",
""
],
[
"Abbott",
"R.",
""
],
[
"Abbott",
"T.",
""
],
[
"Abernathy",
"M. R.",
""
],
[
"Accadia",
"T.",
""
],
[
"Acernese",
"F.",
""
],
[
"Ackley",
"K.",
""
],
[
"Adams",
"C.",
""
],
[
"Adams",
"T.",
""
],
[
"Addesso",
"P.",
""
],
[
"Adhikari",
"R. X.",
""
],
[
"Affeldt",
"C.",
""
],
[
"Agathos",
"M.",
""
],
[
"Aggarwal",
"N.",
""
],
[
"Aguiar",
"O. D.",
""
],
[
"Ain",
"A.",
""
],
[
"Ajith",
"P.",
""
],
[
"Alemic",
"A.",
""
],
[
"Allen",
"B.",
""
],
[
"Allocca",
"A.",
""
],
[
"Amariutei",
"D.",
""
],
[
"Andersen",
"M.",
""
],
[
"Anderson",
"R.",
""
],
[
"Anderson",
"S. B.",
""
],
[
"Anderson",
"W. G.",
""
],
[
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"Walker",
"M.",
""
],
[
"Wallace",
"L.",
""
],
[
"Wang",
"M.",
""
],
[
"Wang",
"X.",
""
],
[
"Ward",
"R. L.",
""
],
[
"Was",
"M.",
""
],
[
"Weaver",
"B.",
""
],
[
"Wei",
"L. -W.",
""
],
[
"Weinert",
"M.",
""
],
[
"Weinstein",
"A. J.",
""
],
[
"Weiss",
"R.",
""
],
[
"Welborn",
"T.",
""
],
[
"Wen",
"L.",
""
],
[
"Wessels",
"P.",
""
],
[
"West",
"M.",
""
],
[
"Westphal",
"T.",
""
],
[
"Wette",
"K.",
""
],
[
"Whelan",
"J. T.",
""
],
[
"White",
"D. J.",
""
],
[
"Whiting",
"B. F.",
""
],
[
"Wiesner",
"K.",
""
],
[
"Wilkinson",
"C.",
""
],
[
"Williams",
"K.",
""
],
[
"Williams",
"L.",
""
],
[
"Williams",
"R.",
""
],
[
"Williams",
"T.",
""
],
[
"Williamson",
"A. R.",
""
],
[
"Willis",
"J. L.",
""
],
[
"Willke",
"B.",
""
],
[
"Wimmer",
"M.",
""
],
[
"Winkler",
"W.",
""
],
[
"Wipf",
"C. C.",
""
],
[
"Wiseman",
"A. G.",
""
],
[
"Wittel",
"H.",
""
],
[
"Woan",
"G.",
""
],
[
"Worden",
"J.",
""
],
[
"Yablon",
"J.",
""
],
[
"Yakushin",
"I.",
""
],
[
"Yamamoto",
"H.",
""
],
[
"Yancey",
"C. C.",
""
],
[
"Yang",
"H.",
""
],
[
"Yang",
"Z.",
""
],
[
"Yoshida",
"S.",
""
],
[
"Yvert",
"M.",
""
],
[
"Zadrożny",
"A.",
""
],
[
"Zanolin",
"M.",
""
],
[
"Zendri",
"J. -P.",
""
],
[
"Zhang",
"Fan",
""
],
[
"Zhang",
"L.",
""
],
[
"Zhao",
"C.",
""
],
[
"Zhu",
"X. J.",
""
],
[
"Zucker",
"M. E.",
""
],
[
"Zuraw",
"S.",
""
],
[
"Zweizig",
"J.",
""
]
] | We present an implementation of the $\mathcal{F}$-statistic to carry out the first search in data from the Virgo laser interferometric gravitational wave detector for periodic gravitational waves from a priori unknown, isolated rotating neutron stars. We searched a frequency $f_0$ range from 100 Hz to 1 kHz and the frequency dependent spindown $f_1$ range from $-1.6\,(f_0/100\,{\rm Hz}) \times 10^{-9}\,$ Hz/s to zero. A large part of this frequency - spindown space was unexplored by any of the all-sky searches published so far. Our method consisted of a coherent search over two-day periods using the $\mathcal{F}$-statistic, followed by a search for coincidences among the candidates from the two-day segments. We have introduced a number of novel techniques and algorithms that allow the use of the Fast Fourier Transform (FFT) algorithm in the coherent part of the search resulting in a fifty-fold speed-up in computation of the $\mathcal{F}$-statistic with respect to the algorithm used in the other pipelines. No significant gravitational wave signal was found. The sensitivity of the search was estimated by injecting signals into the data. In the most sensitive parts of the detector band more than 90% of signals would have been detected with dimensionless gravitational-wave amplitude greater than $5 \times 10^{-24}$. |
2103.03624 | Deyou Chen | Deyou Chen, Chuanhong Gao, Xianming Liu, Chengye Yu | The correspondence between shadow and test field in a four-dimensional
charged Einstein-Gauss-Bonnet black hole | 17 pages | Eur. Phys. J. C 81, 700 (2021) | 10.1140/epjc/s10052-021-09510-0 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this paper, we investigate the photon sphere, shadow radius and
quasinormal modes of a four-dimensional charged Einstein-Gauss-Bonnet black
hole. The perturbation of a massless scalar field in the black hole's
background is adopted. The quasinormal modes are gotten by the $6th$ order WKB
approximation approach and shadow radius, respectively. When the value of the
Gauss-Bonnet coupling constant increase, the values of the real parts of the
quasinormal modes increase and those of the imaginary parts decrease. The
coincidence degrees of quasinormal modes derived by the two approaches
increases with the increase of the values of the Gauss-Bonnet coupling constant
and multiple number. It shows the correspondence between the shadow and test
field in the four-dimensional Einstein-Gauss-Bonnet-Maxwell gravity. The radii
of the photon sphere and shadow increase with the decrease of the Gauss-Bonnet
coupling constant.
| [
{
"created": "Fri, 5 Mar 2021 12:08:32 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Mar 2021 09:25:45 GMT",
"version": "v2"
},
{
"created": "Sun, 8 Aug 2021 02:21:21 GMT",
"version": "v3"
}
] | 2021-09-01 | [
[
"Chen",
"Deyou",
""
],
[
"Gao",
"Chuanhong",
""
],
[
"Liu",
"Xianming",
""
],
[
"Yu",
"Chengye",
""
]
] | In this paper, we investigate the photon sphere, shadow radius and quasinormal modes of a four-dimensional charged Einstein-Gauss-Bonnet black hole. The perturbation of a massless scalar field in the black hole's background is adopted. The quasinormal modes are gotten by the $6th$ order WKB approximation approach and shadow radius, respectively. When the value of the Gauss-Bonnet coupling constant increase, the values of the real parts of the quasinormal modes increase and those of the imaginary parts decrease. The coincidence degrees of quasinormal modes derived by the two approaches increases with the increase of the values of the Gauss-Bonnet coupling constant and multiple number. It shows the correspondence between the shadow and test field in the four-dimensional Einstein-Gauss-Bonnet-Maxwell gravity. The radii of the photon sphere and shadow increase with the decrease of the Gauss-Bonnet coupling constant. |
gr-qc/9901004 | Aharon Davidson | Aharon Davidson and David Karasik | Quantum Gravity of a Brane-like Universe | Revtex, 4 pages, no figures (honorable mentioned, Gravity Research
Foundation 1998) | Mod.Phys.Lett. A13 (1998) 2187-2192 | 10.1142/S0217732398002321 | null | gr-qc hep-th | null | Quantum gravity of a brane-like Universe is formulated, and its Einstein
limit is approached. Regge-Teitelboim embedding of Arnowitt-Deser-Misner
formalism is carried out. Invoking a novel Lagrange multiplier, accompanying
the lapse function and the shift vector, we derive the quadratic Hamiltonian
and the corresponding bifurcated Wheeler-Dewitt-like equation. The inclusion of
arbitrary matter resembles minimal coupling.
| [
{
"created": "Sat, 2 Jan 1999 11:40:14 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Davidson",
"Aharon",
""
],
[
"Karasik",
"David",
""
]
] | Quantum gravity of a brane-like Universe is formulated, and its Einstein limit is approached. Regge-Teitelboim embedding of Arnowitt-Deser-Misner formalism is carried out. Invoking a novel Lagrange multiplier, accompanying the lapse function and the shift vector, we derive the quadratic Hamiltonian and the corresponding bifurcated Wheeler-Dewitt-like equation. The inclusion of arbitrary matter resembles minimal coupling. |
1512.04095 | Vasilis Oikonomou | V.K. Oikonomou | Constraints on Singular Evolution from Gravitational Baryogenesis | Manuscript prepared for submission in International Journal of
Geometric Methods in Modern Physics; References added and clarifications | null | 10.1142/S021988781650033X | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate how the gravitational baryogenesis mechanism can potentially
constrain the form of a Type IV singularity. Specifically, we study two
different models with interesting phenomenology, that realize two distinct Type
IV singularities, one occurring at the end of inflation and one during the
radiation domination era or during the matter domination era. As we
demonstrate, the Type IV singularities occurring at the matter domination era
or during the radiation domination era, are constrained by the gravitational
baryogenesis, in such a way so that these do not render the baryon to entropy
ratio singular. Both the cosmological models we study cannot be realized in the
context of ordinary Einstein-Hilbert gravity, and hence our work can only be
realized in the context of $F(R)$ gravity and more generally in the context of
modified gravity only.
| [
{
"created": "Sun, 13 Dec 2015 18:22:40 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Dec 2015 13:58:17 GMT",
"version": "v2"
}
] | 2016-03-23 | [
[
"Oikonomou",
"V. K.",
""
]
] | We investigate how the gravitational baryogenesis mechanism can potentially constrain the form of a Type IV singularity. Specifically, we study two different models with interesting phenomenology, that realize two distinct Type IV singularities, one occurring at the end of inflation and one during the radiation domination era or during the matter domination era. As we demonstrate, the Type IV singularities occurring at the matter domination era or during the radiation domination era, are constrained by the gravitational baryogenesis, in such a way so that these do not render the baryon to entropy ratio singular. Both the cosmological models we study cannot be realized in the context of ordinary Einstein-Hilbert gravity, and hence our work can only be realized in the context of $F(R)$ gravity and more generally in the context of modified gravity only. |
gr-qc/9909061 | Hiromi Saida | Hiromi Saida and Jiro Soda | Statistical Entropy of BTZ Black Hole in Higher Curvature Gravity | 9 pages, no figure, submitted to Physics Letters B | Phys.Lett. B471 (2000) 358-366 | 10.1016/S0370-2693(99)01405-7 | KUCP0141 | gr-qc hep-th | null | For the BTZ black hole in the Einstein gravity, a statistical entropy has
been calculated to be equal to the Bekenstein-Hawking entropy. In this paper,
the statistical entropy of the BTZ black hole in the higher curvature gravity
is calculated and shown to be equal to the one derived by using the Noether
charge method. This suggests that the equivalence of the geometrical and
statistical entropies of the black hole is retained in the general
diffeomorphism invariant theories of gravity. A relation between the cosmic
censorship conjecture and the unitarity of the conformal field theory on the
boundary of AdS is also discussed.
| [
{
"created": "Tue, 21 Sep 1999 06:39:51 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Nov 1999 09:39:50 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Saida",
"Hiromi",
""
],
[
"Soda",
"Jiro",
""
]
] | For the BTZ black hole in the Einstein gravity, a statistical entropy has been calculated to be equal to the Bekenstein-Hawking entropy. In this paper, the statistical entropy of the BTZ black hole in the higher curvature gravity is calculated and shown to be equal to the one derived by using the Noether charge method. This suggests that the equivalence of the geometrical and statistical entropies of the black hole is retained in the general diffeomorphism invariant theories of gravity. A relation between the cosmic censorship conjecture and the unitarity of the conformal field theory on the boundary of AdS is also discussed. |
1302.7100 | Damiano Anselmi | Damiano Anselmi | Properties Of The Classical Action Of Quantum Gravity | 21 pages; v2: minor changes and proof corrections, JHEP | JHEP 1305 (2013) 028 | 10.1007/JHEP05(2013)028 | IFUP-TH 2013/07 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The classical action of quantum gravity, determined by renormalization,
contains infinitely many independent couplings and can be expressed in
different perturbatively equivalent ways. We organize it in a convenient form,
which is based on invariants constructed with the Weyl tensor. We show that the
FLRW metrics are exact solutions of the field equations in arbitrary
dimensions, and so are all locally conformally flat solutions of the Einstein
equations. Moreover, expanding the metric tensor around locally conformally
flat backgrounds the quadratic part of the action is free of higher
derivatives. Black-hole solutions of Schwarzschild and Kerr type are modified
in a non-trivial way. We work out the first corrections to their metrics and
study their properties.
| [
{
"created": "Thu, 28 Feb 2013 07:05:54 GMT",
"version": "v1"
},
{
"created": "Mon, 13 May 2013 13:26:34 GMT",
"version": "v2"
}
] | 2013-05-14 | [
[
"Anselmi",
"Damiano",
""
]
] | The classical action of quantum gravity, determined by renormalization, contains infinitely many independent couplings and can be expressed in different perturbatively equivalent ways. We organize it in a convenient form, which is based on invariants constructed with the Weyl tensor. We show that the FLRW metrics are exact solutions of the field equations in arbitrary dimensions, and so are all locally conformally flat solutions of the Einstein equations. Moreover, expanding the metric tensor around locally conformally flat backgrounds the quadratic part of the action is free of higher derivatives. Black-hole solutions of Schwarzschild and Kerr type are modified in a non-trivial way. We work out the first corrections to their metrics and study their properties. |
1806.00158 | Huan Yang | Huan Yang, William E. East, Vasileios Paschalidis, Frans Pretorius,
Raissa F. P. Mendes | Evolution of Highly Eccentric Binary Neutron Stars Including Tidal
Effects | 17 pages, 6 figures | Phys. Rev. D 98, 044007 (2018) | 10.1103/PhysRevD.98.044007 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work is the first in a series of studies aimed at understanding the
dynamics of highly eccentric binary neutron stars, and constructing an
appropriate gravitational-waveform model for detection. Such binaries are
possible sources for ground-based gravitational wave detectors, and are
expected to form through dynamical scattering and multi-body interactions in
globular clusters and galactic nuclei. In contrast to black holes, oscillations
of neutron stars are generically excited by tidal effects after close
pericenter passage. Depending on the equation of state, this can enhance the
loss of orbital energy by up to tens of percent over that radiated away by
gravitational waves during an orbit. Under the same interaction mechanism, part
of the orbital angular momentum is also transferred to the star. We calculate
the impact of the neutron star oscillations on the orbital evolution of such
systems, and compare these results to full numerical simulations. Utilizing a
Post-Newtonian flux description we propose a preliminary model to predict the
timing of different pericenter passages. A refined version of this model
(taking into account Post-Newtonian corrections to the tidal coupling and the
oscillations of the stars) may serve as a waveform model for such highly
eccentric systems.
| [
{
"created": "Fri, 1 Jun 2018 01:25:00 GMT",
"version": "v1"
}
] | 2018-08-08 | [
[
"Yang",
"Huan",
""
],
[
"East",
"William E.",
""
],
[
"Paschalidis",
"Vasileios",
""
],
[
"Pretorius",
"Frans",
""
],
[
"Mendes",
"Raissa F. P.",
""
]
] | This work is the first in a series of studies aimed at understanding the dynamics of highly eccentric binary neutron stars, and constructing an appropriate gravitational-waveform model for detection. Such binaries are possible sources for ground-based gravitational wave detectors, and are expected to form through dynamical scattering and multi-body interactions in globular clusters and galactic nuclei. In contrast to black holes, oscillations of neutron stars are generically excited by tidal effects after close pericenter passage. Depending on the equation of state, this can enhance the loss of orbital energy by up to tens of percent over that radiated away by gravitational waves during an orbit. Under the same interaction mechanism, part of the orbital angular momentum is also transferred to the star. We calculate the impact of the neutron star oscillations on the orbital evolution of such systems, and compare these results to full numerical simulations. Utilizing a Post-Newtonian flux description we propose a preliminary model to predict the timing of different pericenter passages. A refined version of this model (taking into account Post-Newtonian corrections to the tidal coupling and the oscillations of the stars) may serve as a waveform model for such highly eccentric systems. |
1909.10336 | Rodrigo von Marttens | R. von Marttens, H. A. Borges, S. Carneiro, J. S. Alcaniz and W.
Zimdahl | Unphysical properties in a class of interacting dark energy models | 17 pages, 7 figures. Accepted for publication in the EPJC | Eur. Phys. J. C 80, 1110 (2020) | 10.1140/epjc/s10052-020-08682-5 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Models with non-gravitational interactions between the dark matter and dark
energy components are an alternative to the standard cosmological scenario.
These models are characterized by an interaction term, and a frequently used
parameterization is $Q = 3\xi H \rho_{x}$, where $H$ is the Hubble parameter
and $\rho_{x}$ is the dark energy density. Although current observations
support such a model for negative values of the interaction parameter $\xi$, we
show here that this interval of values of $\xi$ leads the model to predict a
violation of the Weak Energy Condition (WEC) for the dark matter density,
regardless of the value of the equation-of-state parameter of the dark energy
component. This violation is accompanied by unphysical instabilities of matter
perturbations.
| [
{
"created": "Fri, 20 Sep 2019 15:50:39 GMT",
"version": "v1"
},
{
"created": "Sat, 21 Nov 2020 19:31:09 GMT",
"version": "v2"
}
] | 2020-12-07 | [
[
"von Marttens",
"R.",
""
],
[
"Borges",
"H. A.",
""
],
[
"Carneiro",
"S.",
""
],
[
"Alcaniz",
"J. S.",
""
],
[
"Zimdahl",
"W.",
""
]
] | Models with non-gravitational interactions between the dark matter and dark energy components are an alternative to the standard cosmological scenario. These models are characterized by an interaction term, and a frequently used parameterization is $Q = 3\xi H \rho_{x}$, where $H$ is the Hubble parameter and $\rho_{x}$ is the dark energy density. Although current observations support such a model for negative values of the interaction parameter $\xi$, we show here that this interval of values of $\xi$ leads the model to predict a violation of the Weak Energy Condition (WEC) for the dark matter density, regardless of the value of the equation-of-state parameter of the dark energy component. This violation is accompanied by unphysical instabilities of matter perturbations. |
1510.01169 | Ai Viet Nguyen Dr | Viet Ai Nguyen and Du Tien Pham | Gravity and nonabelian gauge fields in noncommutative space-time | 5 pages, with some corrections | Modern Physics Letters A 32(18):1750095 (2017) | 10.1142/S021773231750095X | IT-VNU Preprint CS-01/2015 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Noncommutative geometric construction of gravity in the two sheeted spacetime
can be viewed as a discretized version of a Kaluza-Klein theory. In this paper,
we show that it is possible to incorporate the nonabelian gauge fields in the
same framework. The generalized Hilbert-Einstein action is gauge invariant only
in two cases. In the first case, the gauge group must be abelian on one sheet
of spacetime and nonabelian on the other one. In the second case, the gauge
group must be the same on two sheets of spacetime. Actually, the theories of
electroweak and strong interactions are exactly these two cases.
| [
{
"created": "Mon, 5 Oct 2015 14:39:48 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Nov 2015 14:06:52 GMT",
"version": "v2"
}
] | 2020-09-25 | [
[
"Nguyen",
"Viet Ai",
""
],
[
"Pham",
"Du Tien",
""
]
] | Noncommutative geometric construction of gravity in the two sheeted spacetime can be viewed as a discretized version of a Kaluza-Klein theory. In this paper, we show that it is possible to incorporate the nonabelian gauge fields in the same framework. The generalized Hilbert-Einstein action is gauge invariant only in two cases. In the first case, the gauge group must be abelian on one sheet of spacetime and nonabelian on the other one. In the second case, the gauge group must be the same on two sheets of spacetime. Actually, the theories of electroweak and strong interactions are exactly these two cases. |
1908.08140 | Iarley P. Lobo Dr | V. B. Bezerra, I. P. Lobo, J. P. Morais Gra\c{c}a and Luis C. N.
Santos | Effects of quantum corrections on the criticality and efficiency of
black holes surrounded by a perfect fluid | 10 pages, 12 figures. References added | null | 10.1140/epjc/s10052-019-7482-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study some properties of the extended phase space of a quantum-corrected
Schwarzschild black hole surrounded by a perfect fluid. In particular we
demonstrate that, due to the quantum correction, there exist first and second
order phase transitions for a certain range of the state parameter of the
perfect fluid, and we explicitly analyze some cases. Besides that, we describe
the efficiency of this system as a heat engine and the effect of quantum
corrections for different surrounding fluids.
| [
{
"created": "Wed, 21 Aug 2019 23:29:22 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Aug 2019 19:19:12 GMT",
"version": "v2"
}
] | 2020-01-08 | [
[
"Bezerra",
"V. B.",
""
],
[
"Lobo",
"I. P.",
""
],
[
"Graça",
"J. P. Morais",
""
],
[
"Santos",
"Luis C. N.",
""
]
] | We study some properties of the extended phase space of a quantum-corrected Schwarzschild black hole surrounded by a perfect fluid. In particular we demonstrate that, due to the quantum correction, there exist first and second order phase transitions for a certain range of the state parameter of the perfect fluid, and we explicitly analyze some cases. Besides that, we describe the efficiency of this system as a heat engine and the effect of quantum corrections for different surrounding fluids. |
1007.3985 | Mubasher Jamil | Kayoomars Karami, Ahmad Sheykhi, Mubasher Jamil, F. Felegary and M.M.
Soltanzadeh | Thermodynamical description of interacting entropy-corrected new
agegraphic dark energy | 8 pages, version accepted for publication in Europhysics Letters
(2011) | Europhys.Lett.93:69001,2011 | 10.1209/0295-5075/93/69001 | arXiv:1007.3985v3 [physics.gen-ph] | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | To explain the accelerating universe driven by dark energy, a so-called
"entropy-corrected new agegraphic dark energy" (ECNADE), was recently proposed
with the help of quantum corrections to the entropy-area relation in the
framework of loop quantum cosmology. Using this definition, we study its
thermodynamical features including entropy and energy conservation. We discuss
the thermodynamical interpretation of the interaction between ECNADE and dark
matter in a non-flat universe bounded by the apparent horizon. We obtain a
relation between the interaction term of the dark components and thermal
fluctuation.
| [
{
"created": "Wed, 21 Jul 2010 06:34:55 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Feb 2011 13:34:48 GMT",
"version": "v2"
},
{
"created": "Wed, 16 Feb 2011 12:28:46 GMT",
"version": "v3"
}
] | 2011-04-21 | [
[
"Karami",
"Kayoomars",
""
],
[
"Sheykhi",
"Ahmad",
""
],
[
"Jamil",
"Mubasher",
""
],
[
"Felegary",
"F.",
""
],
[
"Soltanzadeh",
"M. M.",
""
]
] | To explain the accelerating universe driven by dark energy, a so-called "entropy-corrected new agegraphic dark energy" (ECNADE), was recently proposed with the help of quantum corrections to the entropy-area relation in the framework of loop quantum cosmology. Using this definition, we study its thermodynamical features including entropy and energy conservation. We discuss the thermodynamical interpretation of the interaction between ECNADE and dark matter in a non-flat universe bounded by the apparent horizon. We obtain a relation between the interaction term of the dark components and thermal fluctuation. |
1611.00193 | Hamid Reza Sepangi | Erfan Masaeli, Meysam Motaharfar and Hamid Reza Sepangi | General Scalar-Tensor cosmology: Analytical solutions via Noether
symmetry | 17 pages, to appear in EPJC | Eur.Phys.J. C77 (2017) no.2, 124 | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the cosmology of a general Scalar-Tensor theory which encompasses
generalized Brans-Dicke theory, Gauss-Bonnet gravity, non-minimal derivative
gravity, generalized Galileon gravity and also the general k-essence type
models. Instead of taking into account phenomenological considerations we adopt
a Noether symmetry approach, as a physical criterion, to single out the form of
undetermined functions in the action. These specified functions symmetrize
equations of motion in the simplest possible form which result in exact
solutions. Demanding de Sitter, power-law and bouncing universe solutions in
the absence and presence of matter density leads to exploring new as well as
well-investigated models. We show that there are models for which dynamics of
the system allow transition from a decelerating phase (matter dominated era) to
an accelerating phase (dark energy epoch) and could also lead to general
Brans-Dicke with string correction without a self-interaction potential.
Furthermore, we classify the models based on phantom or quintessence dark
energy point of view. Finally, we obtain the condition for stability of a de
Sitter solution for which the solution is an attractor of the system.
| [
{
"created": "Tue, 1 Nov 2016 11:52:08 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Feb 2017 08:59:58 GMT",
"version": "v2"
}
] | 2017-03-07 | [
[
"Masaeli",
"Erfan",
""
],
[
"Motaharfar",
"Meysam",
""
],
[
"Sepangi",
"Hamid Reza",
""
]
] | We analyze the cosmology of a general Scalar-Tensor theory which encompasses generalized Brans-Dicke theory, Gauss-Bonnet gravity, non-minimal derivative gravity, generalized Galileon gravity and also the general k-essence type models. Instead of taking into account phenomenological considerations we adopt a Noether symmetry approach, as a physical criterion, to single out the form of undetermined functions in the action. These specified functions symmetrize equations of motion in the simplest possible form which result in exact solutions. Demanding de Sitter, power-law and bouncing universe solutions in the absence and presence of matter density leads to exploring new as well as well-investigated models. We show that there are models for which dynamics of the system allow transition from a decelerating phase (matter dominated era) to an accelerating phase (dark energy epoch) and could also lead to general Brans-Dicke with string correction without a self-interaction potential. Furthermore, we classify the models based on phantom or quintessence dark energy point of view. Finally, we obtain the condition for stability of a de Sitter solution for which the solution is an attractor of the system. |
2105.10642 | Jiawei Hu | Jiawei Hu, Hongwei Yu | High frequency background gravitational waves from spontaneous emission
of gravitons by hydrogen and helium | 14 pages, 1 figure, accepted for publication in Eur. Phys. J. C | Eur. Phys. J. C 81, 470 (2021) | 10.1140/epjc/s10052-021-09263-w | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A direct consequence of quantization of gravity would be the existence of
gravitons. Therefore, spontaneous transition of an atom from an excited state
to a lower-lying energy state accompanied with the emission of a graviton is
expected. In this paper, we take the gravitons emitted by hydrogen and helium
in the Universe after recombination as a possible source of high frequency
background gravitational waves, and calculate the energy density spectrum.
Explicit calculations show that the most prominent contribution comes from the
$3d-1s$ transition of singly ionized helium $\mathrm{He}^{+}$, which gives a
peak in frequency at $\sim10^{13}$ Hz. Although the corresponding energy
density is too small to be detected even with state-of-the-art technology
today, we believe that the spontaneous emission of $\mathrm{He}^{+}$ is a
natural source of high frequency gravitational waves, since it is a direct
consequence if we accept that the basic quantum principles we are already
familiar with apply as well to a quantum theory of gravity.
| [
{
"created": "Sat, 22 May 2021 05:20:34 GMT",
"version": "v1"
}
] | 2021-06-03 | [
[
"Hu",
"Jiawei",
""
],
[
"Yu",
"Hongwei",
""
]
] | A direct consequence of quantization of gravity would be the existence of gravitons. Therefore, spontaneous transition of an atom from an excited state to a lower-lying energy state accompanied with the emission of a graviton is expected. In this paper, we take the gravitons emitted by hydrogen and helium in the Universe after recombination as a possible source of high frequency background gravitational waves, and calculate the energy density spectrum. Explicit calculations show that the most prominent contribution comes from the $3d-1s$ transition of singly ionized helium $\mathrm{He}^{+}$, which gives a peak in frequency at $\sim10^{13}$ Hz. Although the corresponding energy density is too small to be detected even with state-of-the-art technology today, we believe that the spontaneous emission of $\mathrm{He}^{+}$ is a natural source of high frequency gravitational waves, since it is a direct consequence if we accept that the basic quantum principles we are already familiar with apply as well to a quantum theory of gravity. |
1103.5114 | Ngangbam Ibohal | Ng. Ibohal and T. Ibungochouba | Hawking's radiation in non-stationary rotating de Sitter background | 13 pages, LaTex format, accepted for publication Astrophysics and
Space Science, Springer; Journal ID: 10509, Article ID: 606, Date 2011-01-15 | Astrophys.Space Sci.333:175-185,2011 | 10.1007/s10509-011-0606-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Hawking's radiation effect of Klein-Gordon scalar field, Dirac particles and
Maxwell's electromagnetic field in the non-stationary rotating de Sitter
cosmological space-time is investigated by using a method of generalized
tortoise co-ordinates transformation. The locations and the temperatures of the
cosmological horizons of the non-stationary rotating de Sitter model are
derived. It is found that the locations and the temperatures of the rotating
cosmological model depend not only on the time but also on the angle. The
stress-energy regularization techniques are applied to the two dimensional
analog of the de Sitter metrics and the calculated stress-energy tensor
contains the thermal radiation effect.
| [
{
"created": "Sat, 26 Mar 2011 07:26:28 GMT",
"version": "v1"
}
] | 2011-04-28 | [
[
"Ibohal",
"Ng.",
""
],
[
"Ibungochouba",
"T.",
""
]
] | Hawking's radiation effect of Klein-Gordon scalar field, Dirac particles and Maxwell's electromagnetic field in the non-stationary rotating de Sitter cosmological space-time is investigated by using a method of generalized tortoise co-ordinates transformation. The locations and the temperatures of the cosmological horizons of the non-stationary rotating de Sitter model are derived. It is found that the locations and the temperatures of the rotating cosmological model depend not only on the time but also on the angle. The stress-energy regularization techniques are applied to the two dimensional analog of the de Sitter metrics and the calculated stress-energy tensor contains the thermal radiation effect. |
1303.0491 | Edwin J. Son | Edwin J. Son, Wontae Kim | Complementary role of the pressure in the black hole thermodynamics | v2. version to appear in PRD; 7 pages, references added | Phys. Rev. D 87, 067502 (2013) | 10.1103/PhysRevD.87.067502 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In black hole thermodynamics of certain models, the thermodynamic first law
may contain the pressure term. The corresponding entropy follows the area law
whereas the thermodynamic energy is not the same with the black hole mass. If
the pressure can be decomposed into two parts and recombined with the original
thermodynamic quantities, then the thermodynamic energy becomes the black hole
mass and the entropy satisfying the area law turns out to be the corrected
entropy called the Wald entropy, respectively.
| [
{
"created": "Sun, 3 Mar 2013 12:33:59 GMT",
"version": "v1"
},
{
"created": "Sat, 16 Mar 2013 06:16:42 GMT",
"version": "v2"
}
] | 2013-04-02 | [
[
"Son",
"Edwin J.",
""
],
[
"Kim",
"Wontae",
""
]
] | In black hole thermodynamics of certain models, the thermodynamic first law may contain the pressure term. The corresponding entropy follows the area law whereas the thermodynamic energy is not the same with the black hole mass. If the pressure can be decomposed into two parts and recombined with the original thermodynamic quantities, then the thermodynamic energy becomes the black hole mass and the entropy satisfying the area law turns out to be the corrected entropy called the Wald entropy, respectively. |
2106.08280 | Dina Traykova | Dina Traykova, Katy Clough, Thomas Helfer, Emanuele Berti, Pedro G.
Ferreira, Lam Hui | Dynamical friction from scalar dark matter in the relativistic regime | 17 pages, 13 figures, 1 table; Version as accepted in PRD - minor
changes | null | 10.1103/PhysRevD.104.103014 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Light bosonic scalars (e.g. axions) may form clouds around black holes via
superradiant instabilities, or via accretion if they form some component of the
dark matter. It has been suggested that their presence may lead to a
distinctive dephasing of the gravitational wave signal when a small compact
object spirals into a larger black hole. Motivated by this, we study
numerically the dynamical friction force on a black hole moving at relativistic
velocities in a background scalar field with an asymptotically homogeneous
energy density. We show that the relativistic scaling is analogous to that
found for supersonic collisional fluids, assuming an approximate expression for
the pressure correction which depends on the velocity and scalar mass. While we
focus on a complex scalar field, our results confirm the expectation that real
scalars would exert a force which oscillates between positive and negative
values in time with a frequency set by the scalar mass. The complex field
describes the time averaged value of this force, but in a real scalar the rapid
force oscillations could in principle leave an imprint on the trajectory. The
approximation we obtain can be used to inform estimates of dephasing in the
final stages of an extreme mass ratio inspiral.
| [
{
"created": "Tue, 15 Jun 2021 16:45:55 GMT",
"version": "v1"
},
{
"created": "Fri, 24 Sep 2021 08:03:40 GMT",
"version": "v2"
},
{
"created": "Wed, 27 Oct 2021 10:38:25 GMT",
"version": "v3"
}
] | 2021-11-24 | [
[
"Traykova",
"Dina",
""
],
[
"Clough",
"Katy",
""
],
[
"Helfer",
"Thomas",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Ferreira",
"Pedro G.",
""
],
[
"Hui",
"Lam",
""
]
] | Light bosonic scalars (e.g. axions) may form clouds around black holes via superradiant instabilities, or via accretion if they form some component of the dark matter. It has been suggested that their presence may lead to a distinctive dephasing of the gravitational wave signal when a small compact object spirals into a larger black hole. Motivated by this, we study numerically the dynamical friction force on a black hole moving at relativistic velocities in a background scalar field with an asymptotically homogeneous energy density. We show that the relativistic scaling is analogous to that found for supersonic collisional fluids, assuming an approximate expression for the pressure correction which depends on the velocity and scalar mass. While we focus on a complex scalar field, our results confirm the expectation that real scalars would exert a force which oscillates between positive and negative values in time with a frequency set by the scalar mass. The complex field describes the time averaged value of this force, but in a real scalar the rapid force oscillations could in principle leave an imprint on the trajectory. The approximation we obtain can be used to inform estimates of dephasing in the final stages of an extreme mass ratio inspiral. |
2012.14110 | Yuri Pavlov | A. A. Grib, Yu. V. Pavlov | Some effects of different coordinate systems in cosmology | 10 pages, no figures | Eur. Phys. J. Plus 136, 318 (2021) | 10.1140/epjp/s13360-021-01249-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The analysis of the dynamics of radial movement in different reference frames
used in cosmology is made. Use of different frames leads to the difference in
inertial forces resulting in different observable effects. The important effect
is the appearance in the system different from the synchronous one of the
acceleration proportional to the distance analogous to the action of the
cosmological constant. Numerical estimate of the difference of this effective
cosmological constant and the invariant constant in Einstein equations is made.
| [
{
"created": "Mon, 28 Dec 2020 06:29:05 GMT",
"version": "v1"
},
{
"created": "Tue, 4 May 2021 09:27:51 GMT",
"version": "v2"
}
] | 2021-05-05 | [
[
"Grib",
"A. A.",
""
],
[
"Pavlov",
"Yu. V.",
""
]
] | The analysis of the dynamics of radial movement in different reference frames used in cosmology is made. Use of different frames leads to the difference in inertial forces resulting in different observable effects. The important effect is the appearance in the system different from the synchronous one of the acceleration proportional to the distance analogous to the action of the cosmological constant. Numerical estimate of the difference of this effective cosmological constant and the invariant constant in Einstein equations is made. |
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