id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/0312076 | Jiro Soda | Jiro Soda, Sugumi Kanno | Inflationary Braneworld Driven By Bulk Scalar Field | 8 pages, no figure; invited talk presented at The 6th RESCEU
International Symposium "Frontier in Astroparticle Physics and Cosmology",
Tokyo, Japan, November 4 - 7, 2003 | null | null | null | gr-qc | null | We have developed a formalism to study an inflationary scenario driven by a
bulk inflaton in the two-brane system. The 4-dimensional low energy effective
action is obtained using the gradient expansion method. It is also found that
the dark radiation and the dark scalar source are expressed by the radion. In
the single-brane limit, we find these dark components disappear. Therefore, it
turns out that the inflation due to the bulk inflaton successfully takes place.
Kaluza-Klein corrections are also taken into account in this case.
| [
{
"created": "Wed, 17 Dec 2003 02:50:47 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Soda",
"Jiro",
""
],
[
"Kanno",
"Sugumi",
""
]
] | We have developed a formalism to study an inflationary scenario driven by a bulk inflaton in the two-brane system. The 4-dimensional low energy effective action is obtained using the gradient expansion method. It is also found that the dark radiation and the dark scalar source are expressed by the radion. In the single-brane limit, we find these dark components disappear. Therefore, it turns out that the inflation due to the bulk inflaton successfully takes place. Kaluza-Klein corrections are also taken into account in this case. |
1501.07096 | Chandra Kant Mishra | Chandra Kant Mishra, K. G. Arun, Bala R. Iyer | Third post-Newtonian gravitational waveforms for compact binary systems
in general orbits: Instantaneous terms | Consistent with the published PRD version; Files (readable in
MATHEMATICA) containing the expressions of all the relevant modes
contributing to the 3PN waveform are included in the "source" | Phys. Rev. D 91, 084040 (2015) | 10.1103/PhysRevD.91.084040 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the instantaneous contributions to the spherical harmonic modes of
gravitational waveforms from compact binary systems in general orbits up to the
third post-Newtonian order. We further extend these results for compact
binaries in quasi-elliptical orbits using the 3PN quasi-Keplerian
representation of the conserved dynamics of compact binaries in eccentric
orbits. Using the multipolar post-Minkowskian formalism, starting from the
different mass and current type multipole moments, we compute the spin weighted
spherical harmonic decomposition of the instantaneous part of the gravitational
waveform. These are terms which are functions of the retarded time and do not
depend on the history of the binary evolution. Together with the hereditary
part, which depends on the binary's dynamical history, these waveforms form the
basis for construction of accurate templates for the detection of gravitational
wave signals from binaries moving in quasi-elliptical orbits.
| [
{
"created": "Wed, 28 Jan 2015 13:33:59 GMT",
"version": "v1"
},
{
"created": "Mon, 11 May 2015 09:08:50 GMT",
"version": "v2"
}
] | 2015-05-12 | [
[
"Mishra",
"Chandra Kant",
""
],
[
"Arun",
"K. G.",
""
],
[
"Iyer",
"Bala R.",
""
]
] | We compute the instantaneous contributions to the spherical harmonic modes of gravitational waveforms from compact binary systems in general orbits up to the third post-Newtonian order. We further extend these results for compact binaries in quasi-elliptical orbits using the 3PN quasi-Keplerian representation of the conserved dynamics of compact binaries in eccentric orbits. Using the multipolar post-Minkowskian formalism, starting from the different mass and current type multipole moments, we compute the spin weighted spherical harmonic decomposition of the instantaneous part of the gravitational waveform. These are terms which are functions of the retarded time and do not depend on the history of the binary evolution. Together with the hereditary part, which depends on the binary's dynamical history, these waveforms form the basis for construction of accurate templates for the detection of gravitational wave signals from binaries moving in quasi-elliptical orbits. |
1809.04616 | Qing-Qing Zhao | Qing-Qing Zhao, Yue-Zhou Li, H. Lu | Static Equilibria of Charged Particles Around Charged Black Holes: Chaos
Bound and Its Violations | Latex, 29 pages, 1 figure | Phys. Rev. D 98, 124001 (2018) | 10.1103/PhysRevD.98.124001 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the static equilibrium of a charged massive particle around a
charged black hole, balanced by the Lorentz force. For a given black hole, the
equilibrium surface is determined by the charge/mass ratio of the particle. By
investigating a large class of charged black holes, we find that the equilibria
can be stable, marginal or unstable. We focus on the unstable equilibria which
signal chaotic motions and we obtain the corresponding Lyapunov exponents
$\lambda$. We find that although $\lambda$ approaches universally the horizon
surface gravity $\kappa$ when the equilibria are close to the horizon, the
proposed chaotic motion bound $\lambda<\kappa$ is satisfied only by some
specific black holes including the RN and RN-AdS black holes. The bound can be
violated by a large number of black holes including the RN-dS black holes or
black holes in Einstein-Maxwell-Dilaton, Einstein-Born-Infeld and
Einstein-Gauss-Bonnet-Maxwell gravities. We find that unstable equilibria can
even exist in extremal black holes, implying that the ratio $\lambda/\kappa$
can be arbitrarily large for sufficiently small $\kappa$. Our investigation
does suggest a universal bound for sufficiently large $\kappa$, namely
$\lambda/\kappa <{\cal C}$ for some order-one constant ${\cal C}$.
| [
{
"created": "Wed, 12 Sep 2018 18:03:12 GMT",
"version": "v1"
}
] | 2018-12-12 | [
[
"Zhao",
"Qing-Qing",
""
],
[
"Li",
"Yue-Zhou",
""
],
[
"Lu",
"H.",
""
]
] | We study the static equilibrium of a charged massive particle around a charged black hole, balanced by the Lorentz force. For a given black hole, the equilibrium surface is determined by the charge/mass ratio of the particle. By investigating a large class of charged black holes, we find that the equilibria can be stable, marginal or unstable. We focus on the unstable equilibria which signal chaotic motions and we obtain the corresponding Lyapunov exponents $\lambda$. We find that although $\lambda$ approaches universally the horizon surface gravity $\kappa$ when the equilibria are close to the horizon, the proposed chaotic motion bound $\lambda<\kappa$ is satisfied only by some specific black holes including the RN and RN-AdS black holes. The bound can be violated by a large number of black holes including the RN-dS black holes or black holes in Einstein-Maxwell-Dilaton, Einstein-Born-Infeld and Einstein-Gauss-Bonnet-Maxwell gravities. We find that unstable equilibria can even exist in extremal black holes, implying that the ratio $\lambda/\kappa$ can be arbitrarily large for sufficiently small $\kappa$. Our investigation does suggest a universal bound for sufficiently large $\kappa$, namely $\lambda/\kappa <{\cal C}$ for some order-one constant ${\cal C}$. |
gr-qc/9801055 | Jorge Pullin | R. Gambini, O. Obregon, J. Pullin | Yang-Mills analogues of the Immirzi ambiguity | 5 pages, revtex, no figures | Phys.Rev. D59 (1999) 047505 | 10.1103/PhysRevD.59.047505 | CGPG-98/1-2 | gr-qc | null | We draw parallels between the recently introduced ``Immirzi ambiguity'' of
the Ashtekar-like formulation of canonical quantum gravity and other
ambiguities that appear in Yang-Mills theories, like the $\theta$ ambiguity. We
also discuss ambiguities in the Maxwell case, and implication for the loop
quantization of these theories.
| [
{
"created": "Thu, 15 Jan 1998 18:16:01 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Gambini",
"R.",
""
],
[
"Obregon",
"O.",
""
],
[
"Pullin",
"J.",
""
]
] | We draw parallels between the recently introduced ``Immirzi ambiguity'' of the Ashtekar-like formulation of canonical quantum gravity and other ambiguities that appear in Yang-Mills theories, like the $\theta$ ambiguity. We also discuss ambiguities in the Maxwell case, and implication for the loop quantization of these theories. |
0912.3691 | Ingemar Bengtsson | Jan E. Aman, Ingemar Bengtsson, and Jos\'e M. M. Senovilla | Where are the trapped surfaces? | 6 pages, 1 figure; talk at the Spanish Relativity Meeting ERE09 in
Bilbao | J.Phys.Conf.Ser.229:012004,2010 | 10.1088/1742-6596/229/1/012004 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the boundary of the spacetime region through each point of which a
trapped surface passes, first in some simple soluble examples, and then in the
self-similar Vaidya solution. For the latter the boundary must lie strictly
inside the event horizon. We present a class of closed trapped surfaces
extending strictly outside the apparent horizon.
| [
{
"created": "Fri, 18 Dec 2009 14:56:49 GMT",
"version": "v1"
}
] | 2010-07-26 | [
[
"Aman",
"Jan E.",
""
],
[
"Bengtsson",
"Ingemar",
""
],
[
"Senovilla",
"José M. M.",
""
]
] | We discuss the boundary of the spacetime region through each point of which a trapped surface passes, first in some simple soluble examples, and then in the self-similar Vaidya solution. For the latter the boundary must lie strictly inside the event horizon. We present a class of closed trapped surfaces extending strictly outside the apparent horizon. |
1405.1508 | Cosimo Bambi | Lingyao Kong, Zilong Li, Cosimo Bambi | Constraints on the spacetime geometry around 10 stellar-mass black hole
candidates from the disk's thermal spectrum | 13 pages, 7 figures. v2: refereed version | Astrophys.J.797:78,2014 | 10.1088/0004-637X/797/2/78 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a previous paper, one of us has described a code to compute the thermal
spectrum of geometrically thin and optically thick accretion disks around
generic stationary and axisymmetric black holes, which are not necessarily of
the Kerr type. As the structure of the accretion disk and the propagation of
electromagnetic radiation from the disk to the distant observer depend on the
background metric, the analysis of the thermal spectrum of thin disks can be
used to test the actual nature of black hole candidates. In this paper, we
consider the 10 stellar-mass black hole candidates for which the spin parameter
has been already estimated from the analysis of the disk's thermal spectrum and
under the assumption of the Kerr background, and we translate the measurements
reported in the literature into constraints on the spin parameter--deformation
parameter plane. The analysis of the disk's thermal spectrum can be used to
estimate only one parameter of the geometry close to the compact object, and
therefore it is not possible to get independent measurements of both the spin
and the deformation parameters. The constraints obtained here will be used in
combination with other measurements in future work, with the final goal to
break the degeneracy between the spin and possible deviations from the Kerr
solution and thus test the Kerr black hole hypothesis.
| [
{
"created": "Wed, 7 May 2014 05:47:30 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Oct 2014 01:57:06 GMT",
"version": "v2"
}
] | 2014-12-03 | [
[
"Kong",
"Lingyao",
""
],
[
"Li",
"Zilong",
""
],
[
"Bambi",
"Cosimo",
""
]
] | In a previous paper, one of us has described a code to compute the thermal spectrum of geometrically thin and optically thick accretion disks around generic stationary and axisymmetric black holes, which are not necessarily of the Kerr type. As the structure of the accretion disk and the propagation of electromagnetic radiation from the disk to the distant observer depend on the background metric, the analysis of the thermal spectrum of thin disks can be used to test the actual nature of black hole candidates. In this paper, we consider the 10 stellar-mass black hole candidates for which the spin parameter has been already estimated from the analysis of the disk's thermal spectrum and under the assumption of the Kerr background, and we translate the measurements reported in the literature into constraints on the spin parameter--deformation parameter plane. The analysis of the disk's thermal spectrum can be used to estimate only one parameter of the geometry close to the compact object, and therefore it is not possible to get independent measurements of both the spin and the deformation parameters. The constraints obtained here will be used in combination with other measurements in future work, with the final goal to break the degeneracy between the spin and possible deviations from the Kerr solution and thus test the Kerr black hole hypothesis. |
gr-qc/9412013 | Dirk Graudenz | Dirk Graudenz (CERN) | On the Space-Time Geometry of Quantum Systems | 15 pages (LaTeX); figures are included via epsfig; the corresponding
postscript files are uuencoded; AMS-fonts are needed | null | null | CERN-TH.7516/94 | gr-qc hep-th | null | We describe the time evolution of quantum systems in a classical background
space-time by means of a covariant derivative in an infinite dimensional vector
bundle. The corresponding parallel transport operator along a timelike curve
$\cC$ is interpreted as the time evolution operator of an observer moving along
$\cC$. The holonomy group of the connection, which can be interpreted as a
group of local symmetry transformations, and the set of observables have to
satisfy certain consistency conditions. Two examples related to local
$\mbox{SO}(3)$ and $\mbox{U}(1)$-symmetries, respectively, are discussed in
detail. The theory developed in this paper may also be useful to analyze
situations where the underlying space-time manifold has closed timelike curves.
| [
{
"created": "Mon, 5 Dec 1994 11:52:07 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Graudenz",
"Dirk",
"",
"CERN"
]
] | We describe the time evolution of quantum systems in a classical background space-time by means of a covariant derivative in an infinite dimensional vector bundle. The corresponding parallel transport operator along a timelike curve $\cC$ is interpreted as the time evolution operator of an observer moving along $\cC$. The holonomy group of the connection, which can be interpreted as a group of local symmetry transformations, and the set of observables have to satisfy certain consistency conditions. Two examples related to local $\mbox{SO}(3)$ and $\mbox{U}(1)$-symmetries, respectively, are discussed in detail. The theory developed in this paper may also be useful to analyze situations where the underlying space-time manifold has closed timelike curves. |
0902.4669 | Nicolas Yunes | Nicolas Yunes and Frans Pretorius | Dynamical Chern-Simons Modified Gravity I: Spinning Black Holes in the
Slow-Rotation Approximation | 13 pages, no figures, replaced with version accepted for publication
in Phys. Rev. D. This version corrects a minor typo in Eq. 1 of the published
version | Phys.Rev.D79:084043,2009 | 10.1103/PhysRevD.79.084043 | null | gr-qc astro-ph.CO astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The low-energy limit of string theory contains an anomaly-canceling
correction to the Einstein-Hilbert action, which defines an effective theory:
Chern-Simons (CS) modified gravity. The CS correction consists of the product
of a scalar field with the Pontryagin density, where the former can be treated
as a background field (non-dynamical formulation) or as an evolving field
(dynamical formulation). Many solutions of general relativity persist in the
modified theory; a notable exception is the Kerr metric, which has sparked a
search for rotating black hole solutions. Here, for the first time, we find a
solution describing a rotating black hole within the dynamical framework, and
in the small-coupling/slow-rotation limit. The solution is axisymmetric and
stationary, constituting a deformation of the Kerr metric with dipole scalar
"hair," whose effect on geodesic motion is to weaken the frame-dragging effect
and shift the location of the inner-most stable circular orbit outwards
(inwards) relative to Kerr for co-rotating (counter-rotating) geodesics. We
further show that the correction to the metric scales inversely with the fourth
power of the radial distance to the black hole, suggesting it will escape any
meaningful bounds from weak-field experiments. For example, using binary pulsar
data we can only place an initial bound on the magnitude of the dynamical
coupling constant of $\xi^{1/4} \lesssim 10^{4} {\textrm{km}}$. More stringent
bounds will require observations of inherently strong-field phenomena.
| [
{
"created": "Thu, 26 Feb 2009 19:18:59 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Apr 2009 15:40:21 GMT",
"version": "v2"
},
{
"created": "Sun, 16 Aug 2009 13:30:37 GMT",
"version": "v3"
}
] | 2009-10-29 | [
[
"Yunes",
"Nicolas",
""
],
[
"Pretorius",
"Frans",
""
]
] | The low-energy limit of string theory contains an anomaly-canceling correction to the Einstein-Hilbert action, which defines an effective theory: Chern-Simons (CS) modified gravity. The CS correction consists of the product of a scalar field with the Pontryagin density, where the former can be treated as a background field (non-dynamical formulation) or as an evolving field (dynamical formulation). Many solutions of general relativity persist in the modified theory; a notable exception is the Kerr metric, which has sparked a search for rotating black hole solutions. Here, for the first time, we find a solution describing a rotating black hole within the dynamical framework, and in the small-coupling/slow-rotation limit. The solution is axisymmetric and stationary, constituting a deformation of the Kerr metric with dipole scalar "hair," whose effect on geodesic motion is to weaken the frame-dragging effect and shift the location of the inner-most stable circular orbit outwards (inwards) relative to Kerr for co-rotating (counter-rotating) geodesics. We further show that the correction to the metric scales inversely with the fourth power of the radial distance to the black hole, suggesting it will escape any meaningful bounds from weak-field experiments. For example, using binary pulsar data we can only place an initial bound on the magnitude of the dynamical coupling constant of $\xi^{1/4} \lesssim 10^{4} {\textrm{km}}$. More stringent bounds will require observations of inherently strong-field phenomena. |
gr-qc/0303106 | Michael J. Pfenning | Christopher J. Fewster and Michael J. Pfenning | A Quantum Weak Energy Inequality for Spin-One Fields in Curved Spacetime | RevTex4, 29 pages, 1 figure | J.Math.Phys. 44 (2003) 4480-4513 | 10.1063/1.1602554 | Erwin Schrodinger Institute 1295 (2003) | gr-qc math-ph math.MP | null | Quantum weak energy inequalities (QWEI) provide state-independent lower
bounds on averages of the renormalised energy density of a quantum field. We
derive QWEIs for the electromagnetic and massive spin-one fields in globally
hyperbolic spacetimes whose Cauchy surfaces are compact and have trivial first
homology group. These inequalities provide lower bounds on weighted averages of
the renormalized energy density as ``measured'' along an arbitrary timelike
trajectory, and are valid for arbitrary Hadamard states of the spin-one fields.
The QWEI bound takes a particularly simple form for averaging along static
trajectories in ultrastatic spacetimes; as specific examples we consider
Minkowski space [in which case the topological restrictions may be dispensed
with] and the static Einstein universe.
A significant part of the paper is devoted to the definition and properties
of Hadamard states of spin-one fields in curved spacetimes, particularly with
regard to their microlocal behaviour.
| [
{
"created": "Wed, 26 Mar 2003 16:03:00 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Fewster",
"Christopher J.",
""
],
[
"Pfenning",
"Michael J.",
""
]
] | Quantum weak energy inequalities (QWEI) provide state-independent lower bounds on averages of the renormalised energy density of a quantum field. We derive QWEIs for the electromagnetic and massive spin-one fields in globally hyperbolic spacetimes whose Cauchy surfaces are compact and have trivial first homology group. These inequalities provide lower bounds on weighted averages of the renormalized energy density as ``measured'' along an arbitrary timelike trajectory, and are valid for arbitrary Hadamard states of the spin-one fields. The QWEI bound takes a particularly simple form for averaging along static trajectories in ultrastatic spacetimes; as specific examples we consider Minkowski space [in which case the topological restrictions may be dispensed with] and the static Einstein universe. A significant part of the paper is devoted to the definition and properties of Hadamard states of spin-one fields in curved spacetimes, particularly with regard to their microlocal behaviour. |
gr-qc/9908071 | Elisa Di Pietro | Elisa Di Pietro and Jacques Demaret | A constant equation of state for quintessence ? | 9 pages, no figures. Submitted to IJMPD. Typos corrected | Int.J.Mod.Phys. D10 (2001) 231-237 | 10.1142/S0218271801000779 | null | gr-qc | null | Quintessence is often invoked to explain the universe acceleration suggested
by the type Ia supernovae observations. The aim of this letter is to study the
validity of using a constant equation of state for quintessence models. We
shall show that this hypothesis strongly constraint the form of the scalar
potential.
| [
{
"created": "Fri, 27 Aug 1999 16:50:22 GMT",
"version": "v1"
},
{
"created": "Fri, 25 Aug 2000 13:50:17 GMT",
"version": "v2"
},
{
"created": "Tue, 5 Sep 2000 09:07:52 GMT",
"version": "v3"
}
] | 2016-08-31 | [
[
"Di Pietro",
"Elisa",
""
],
[
"Demaret",
"Jacques",
""
]
] | Quintessence is often invoked to explain the universe acceleration suggested by the type Ia supernovae observations. The aim of this letter is to study the validity of using a constant equation of state for quintessence models. We shall show that this hypothesis strongly constraint the form of the scalar potential. |
gr-qc/9606086 | null | Hisashi Onozawa, Takashi Okamura, Takashi Mishima and Hideki Ishihara
(Tokyo Inst. of Tech.) | Perturbing Supersymmetric Black Hole | 4 pages, 2 eps figures, REVTEX | Phys.Rev.D55:4529-4531,1997 | 10.1103/PhysRevD.55.4529 | TIT-HEP-334/COSMO-73 | gr-qc hep-th | null | An investigation of the perturbations of the Reissner-Nordstr\"{o}m black
hole in the $N=2$ supergravity is presented. We prove in the extremal limit
that the black hole responds to the perturbation of each field in the same
manner. We conjecture that we can match the modes of the graviton, gravitino
and photon because of supersymmetry transformations.
| [
{
"created": "Sat, 29 Jun 1996 07:59:45 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Oct 1996 12:21:57 GMT",
"version": "v2"
}
] | 2009-12-30 | [
[
"Onozawa",
"Hisashi",
"",
"Tokyo Inst. of Tech."
],
[
"Okamura",
"Takashi",
"",
"Tokyo Inst. of Tech."
],
[
"Mishima",
"Takashi",
"",
"Tokyo Inst. of Tech."
],
[
"Ishihara",
"Hideki",
"",
"Tokyo Inst. of Tech."
]
] | An investigation of the perturbations of the Reissner-Nordstr\"{o}m black hole in the $N=2$ supergravity is presented. We prove in the extremal limit that the black hole responds to the perturbation of each field in the same manner. We conjecture that we can match the modes of the graviton, gravitino and photon because of supersymmetry transformations. |
1210.7566 | Xianghui Luo | Xianghui Luo, James Isenberg | Power Law Inflation with Electromagnetism | 56 pages | Ann.Phys. 334(2013)420-454 | null | null | gr-qc math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We generalize Ringstr\"om's global future causal stability results
(Ringstr\"om 2009) for certain expanding cosmological solutions of the
Einstein-scalar field equations to solutions of the Einstein-Maxwell-scalar
field system. In particular, after noting that the power law inflationary
spacetimes $(M^{n+1}, \hat{g}, \hat{\phi})$ considered by Ringstr\"om in
Ringstr\"om (2009) are solutions of the Einstein-Maxwell-scalar field system
(with exponential potential) as well as of the Einstein-scalar field system
(with the same exponential potential), we consider (nonlinear) perturbations of
initial data sets of these spacetimes which include electromagnetic
perturbations as well as gravitational and scalar perturbations. We show that
if (as in Ringstr\"om, 2009) we focus on pairs of relatively scaled open sets
$U_{R_0} \subset U_{4R_0}$ on an initial slice of $(M^{n+1}, \hat{g})$, and if
we choose a set of perturbed data which on $ U_{4R_0}$ is sufficiently close to
that of $(M^{n+1}, \hat{g},\hat{\phi},\hat{A}=0)$, then in the maximal globally
hyperbolic spacetime development $(M^{n+1},g,\phi,A)$ of this data via the
Einstein-Maxwell-scalar field equations, all causal geodesics emanating from
$U_{R_0}$ are future complete (just as in $(M^{n+1}, \hat{g})$). We also verify
the controlled future asymptotic behavior of the fields in the spacetime
developments of the perturbed data sets.
| [
{
"created": "Mon, 29 Oct 2012 05:22:38 GMT",
"version": "v1"
}
] | 2017-05-19 | [
[
"Luo",
"Xianghui",
""
],
[
"Isenberg",
"James",
""
]
] | We generalize Ringstr\"om's global future causal stability results (Ringstr\"om 2009) for certain expanding cosmological solutions of the Einstein-scalar field equations to solutions of the Einstein-Maxwell-scalar field system. In particular, after noting that the power law inflationary spacetimes $(M^{n+1}, \hat{g}, \hat{\phi})$ considered by Ringstr\"om in Ringstr\"om (2009) are solutions of the Einstein-Maxwell-scalar field system (with exponential potential) as well as of the Einstein-scalar field system (with the same exponential potential), we consider (nonlinear) perturbations of initial data sets of these spacetimes which include electromagnetic perturbations as well as gravitational and scalar perturbations. We show that if (as in Ringstr\"om, 2009) we focus on pairs of relatively scaled open sets $U_{R_0} \subset U_{4R_0}$ on an initial slice of $(M^{n+1}, \hat{g})$, and if we choose a set of perturbed data which on $ U_{4R_0}$ is sufficiently close to that of $(M^{n+1}, \hat{g},\hat{\phi},\hat{A}=0)$, then in the maximal globally hyperbolic spacetime development $(M^{n+1},g,\phi,A)$ of this data via the Einstein-Maxwell-scalar field equations, all causal geodesics emanating from $U_{R_0}$ are future complete (just as in $(M^{n+1}, \hat{g})$). We also verify the controlled future asymptotic behavior of the fields in the spacetime developments of the perturbed data sets. |
2112.05397 | Carlos Heredia Pimienta | Carlos Heredia, Ivan Kol\'a\v{r}, Josep Llosa, Francisco Jos\'e
Maldonado Torralba, Anupam Mazumdar | Infinite-derivative linearized gravity in convolutional form | 23 pages, comments welcome! | Class. Quantum Grav. 39 (2022) 085001 | 10.1088/1361-6382/ac5a14 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article aims to transform the infinite-order Lagrangian density for
ghost-free infinite-derivative linearized gravity into non-local. To achieve
it, we use the theory of generalized functions and the Fourier transform in the
space of tempered distributions $\mathcal{S}^\prime$. We show that the
non-local operator domain is not defined on the whole functional space but on a
subset of it. Moreover, we prove that these functions and their derivatives are
bounded in all $\mathbb{R}^3$ and, consequently, the Riemann tensor is regular
and the scalar curvature invariants do not present any spacetime singularity.
Finally, we explore what conditions we need to satisfy so that the solutions of
the linearized equations of motion exist in $\mathcal{S}^\prime$.
| [
{
"created": "Fri, 10 Dec 2021 09:02:38 GMT",
"version": "v1"
}
] | 2022-03-30 | [
[
"Heredia",
"Carlos",
""
],
[
"Kolář",
"Ivan",
""
],
[
"Llosa",
"Josep",
""
],
[
"Torralba",
"Francisco José Maldonado",
""
],
[
"Mazumdar",
"Anupam",
""
]
] | This article aims to transform the infinite-order Lagrangian density for ghost-free infinite-derivative linearized gravity into non-local. To achieve it, we use the theory of generalized functions and the Fourier transform in the space of tempered distributions $\mathcal{S}^\prime$. We show that the non-local operator domain is not defined on the whole functional space but on a subset of it. Moreover, we prove that these functions and their derivatives are bounded in all $\mathbb{R}^3$ and, consequently, the Riemann tensor is regular and the scalar curvature invariants do not present any spacetime singularity. Finally, we explore what conditions we need to satisfy so that the solutions of the linearized equations of motion exist in $\mathcal{S}^\prime$. |
2402.11150 | Neil Ashby | Neil Ashby and Bijunath Patla | A Relativistic Framework to Establish Coordinate Time on the Moon and
Beyond | null | null | null | null | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | As humanity aspires to explore the solar system and investigate distant
worlds such as the Moon, Mars, and beyond, there is a growing need to establish
and broaden coordinate time references that depend on the rate of standard
clocks. According to Einstein's theory of relativity, the rate of a standard
clock is influenced by the gravitational potential at the location of the clock
and the relative motion of the clock. A coordinate time reference is
established by a grid of synchronized clocks traceable to an ideal clock at a
predetermined point in space. This allows for the comparison of local time
variations of clocks due to gravitational and kinematic effects. We present a
relativistic framework to introduce a coordinate time for the Moon. This
framework also establishes a relationship between the coordinate times for the
Moon and the Earth as determined by standard clocks located on the Earth's
geoid and the Moon's equator. A clock near the Moon's equator ticks faster than
one near the Earth's equator, accumulating an extra 56.02 microseconds per day
over the duration of a lunar orbit. This formalism is then used to compute the
clock rates at Earth-Moon Lagrange points. Accurate estimation of the rate
differences of coordinate times across celestial bodies and their
inter-comparisons using clocks onboard orbiters at relatively stable Lagrange
points as time transfer links is crucial for establishing reliable
communications infrastructure. This understanding also underpins precise
navigation in cislunar space and on celestial bodies' surfaces, thus playing a
pivotal role in ensuring the interoperability of various position, navigation,
and timing (PNT) systems spanning from Earth to the Moon and to the farthest
regions of the inner solar system.
| [
{
"created": "Sat, 17 Feb 2024 00:33:58 GMT",
"version": "v1"
}
] | 2024-02-20 | [
[
"Ashby",
"Neil",
""
],
[
"Patla",
"Bijunath",
""
]
] | As humanity aspires to explore the solar system and investigate distant worlds such as the Moon, Mars, and beyond, there is a growing need to establish and broaden coordinate time references that depend on the rate of standard clocks. According to Einstein's theory of relativity, the rate of a standard clock is influenced by the gravitational potential at the location of the clock and the relative motion of the clock. A coordinate time reference is established by a grid of synchronized clocks traceable to an ideal clock at a predetermined point in space. This allows for the comparison of local time variations of clocks due to gravitational and kinematic effects. We present a relativistic framework to introduce a coordinate time for the Moon. This framework also establishes a relationship between the coordinate times for the Moon and the Earth as determined by standard clocks located on the Earth's geoid and the Moon's equator. A clock near the Moon's equator ticks faster than one near the Earth's equator, accumulating an extra 56.02 microseconds per day over the duration of a lunar orbit. This formalism is then used to compute the clock rates at Earth-Moon Lagrange points. Accurate estimation of the rate differences of coordinate times across celestial bodies and their inter-comparisons using clocks onboard orbiters at relatively stable Lagrange points as time transfer links is crucial for establishing reliable communications infrastructure. This understanding also underpins precise navigation in cislunar space and on celestial bodies' surfaces, thus playing a pivotal role in ensuring the interoperability of various position, navigation, and timing (PNT) systems spanning from Earth to the Moon and to the farthest regions of the inner solar system. |
1909.05258 | Emanuele Berti | F\'elix-Louis Juli\'e, Emanuele Berti | Post-Newtonian dynamics and black hole thermodynamics in
Einstein-scalar-Gauss-Bonnet gravity | 20 pages, 4 figures | Phys. Rev. D 100, 104061 (2019) | 10.1103/PhysRevD.100.104061 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the post-Newtonian dynamics of black hole binaries in
Einstein-scalar-Gauss-Bonnet gravity theories. To this aim we build static,
spherically symmetric black hole solutions at fourth order in the Gauss-Bonnet
coupling $\alpha$. We then "skeletonize" these solutions by reducing them to
point particles with scalar field-dependent masses, showing that this procedure
amounts to fixing the Wald entropy of the black holes during their slow
inspiral. The cosmological value of the scalar field plays a crucial role in
the dynamics of the binary. We compute the two-body Lagrangian at first
post-Newtonian order and show that no regularization procedure is needed to
obtain the Gauss-Bonnet contributions to the fields, which are finite. We
illustrate the power of our approach by Pad\'e-resumming the so-called
"sensitivities," which measure the coupling of the skeletonized body to the
scalar field, for some specific theories of interest.
| [
{
"created": "Wed, 11 Sep 2019 18:00:01 GMT",
"version": "v1"
}
] | 2019-12-04 | [
[
"Julié",
"Félix-Louis",
""
],
[
"Berti",
"Emanuele",
""
]
] | We study the post-Newtonian dynamics of black hole binaries in Einstein-scalar-Gauss-Bonnet gravity theories. To this aim we build static, spherically symmetric black hole solutions at fourth order in the Gauss-Bonnet coupling $\alpha$. We then "skeletonize" these solutions by reducing them to point particles with scalar field-dependent masses, showing that this procedure amounts to fixing the Wald entropy of the black holes during their slow inspiral. The cosmological value of the scalar field plays a crucial role in the dynamics of the binary. We compute the two-body Lagrangian at first post-Newtonian order and show that no regularization procedure is needed to obtain the Gauss-Bonnet contributions to the fields, which are finite. We illustrate the power of our approach by Pad\'e-resumming the so-called "sensitivities," which measure the coupling of the skeletonized body to the scalar field, for some specific theories of interest. |
2207.00030 | Viola De Renzis | Viola De Renzis, Davide Gerosa, Geraint Pratten, Patricia Schmidt,
Matthew Mould | Characterization of merging black holes with two precessing spins | 12 pages, 8 figures, 1 table | Phys. Rev. D 106, 084040 (2022) | 10.1103/PhysRevD.106.084040 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spin precession in merging black-hole binaries is a treasure trove for both
astrophysics and fundamental physics. There are now well-established strategies
to infer from gravitational-wave data whether at least one of the two black
holes is precessing. In this paper we tackle the next-in-line target, namely
the statistical assessment that the observed system has two precessing spins.
We find that the recently developed generalization of the effective precession
spin parameter $\chi_\mathrm{p}$ is a well-suited estimator to this task. With
this estimator, the occurrence of two precessing spins is a necessary (though
not sufficient) condition to obtain values $1<\chi_\mathrm{p}\leq 2$. Confident
measurements of gravitational-wave sources with $\chi_\mathrm{p}$ values in
this range can be taken as a conservative assessment that the binary presents
two precessing spins. We investigate this argument using a large set of >100
software injections assuming anticipated LIGO/Virgo sensitivities for the
upcoming fourth observing run, O4. Our results are very encouraging, suggesting
that, if such binaries exist in nature and merge at a sufficient rate, current
interferometers are likely to deliver the first confident detection of merging
black holes with two precessing spins. We investigate prior effects and
waveform systematics and, though these need to be better investigated, did not
find any confident false-positive case among all the configurations we tested.
Our assessment should thus be taken as conservative.
| [
{
"created": "Thu, 30 Jun 2022 18:00:24 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Oct 2022 15:51:21 GMT",
"version": "v2"
}
] | 2022-10-24 | [
[
"De Renzis",
"Viola",
""
],
[
"Gerosa",
"Davide",
""
],
[
"Pratten",
"Geraint",
""
],
[
"Schmidt",
"Patricia",
""
],
[
"Mould",
"Matthew",
""
]
] | Spin precession in merging black-hole binaries is a treasure trove for both astrophysics and fundamental physics. There are now well-established strategies to infer from gravitational-wave data whether at least one of the two black holes is precessing. In this paper we tackle the next-in-line target, namely the statistical assessment that the observed system has two precessing spins. We find that the recently developed generalization of the effective precession spin parameter $\chi_\mathrm{p}$ is a well-suited estimator to this task. With this estimator, the occurrence of two precessing spins is a necessary (though not sufficient) condition to obtain values $1<\chi_\mathrm{p}\leq 2$. Confident measurements of gravitational-wave sources with $\chi_\mathrm{p}$ values in this range can be taken as a conservative assessment that the binary presents two precessing spins. We investigate this argument using a large set of >100 software injections assuming anticipated LIGO/Virgo sensitivities for the upcoming fourth observing run, O4. Our results are very encouraging, suggesting that, if such binaries exist in nature and merge at a sufficient rate, current interferometers are likely to deliver the first confident detection of merging black holes with two precessing spins. We investigate prior effects and waveform systematics and, though these need to be better investigated, did not find any confident false-positive case among all the configurations we tested. Our assessment should thus be taken as conservative. |
2006.00907 | Faizuddin Ahmed | Faizuddin Ahmed | Investigation of spin-$0$ massive charged particle subject to a
homogeneous magnetic field with potentials in a topologically trivial flat
class of G\"{o}del-type space-time | 22 pages, accepted for publication in Adv. High Energy Physics
journal | Adv. High Energy Physics Volume 2020, Article ID 7943436 (2020) | 10.1155/2020/7943436 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate relativistic quantum dynamics of spin- $0$
massive charged particle subject to a homogeneous magnetic field in the
G\"{o}del-type space-time with potentials. We solve the Klein-Gordon equation
subject to a homogeneous magnetic field in a topologically trivial flat class
of G\"{o}del-type space-time in the presence of a Cornell-type scalar and
Coulomb-type vector potentials and analyze the effects on the energy
eigenvalues and eigenfunctions.
| [
{
"created": "Fri, 29 May 2020 14:45:56 GMT",
"version": "v1"
}
] | 2020-06-12 | [
[
"Ahmed",
"Faizuddin",
""
]
] | In this paper, we investigate relativistic quantum dynamics of spin- $0$ massive charged particle subject to a homogeneous magnetic field in the G\"{o}del-type space-time with potentials. We solve the Klein-Gordon equation subject to a homogeneous magnetic field in a topologically trivial flat class of G\"{o}del-type space-time in the presence of a Cornell-type scalar and Coulomb-type vector potentials and analyze the effects on the energy eigenvalues and eigenfunctions. |
2310.05780 | Andronikos Paliathanasis | Andronikos Paliathanasis | Lie symmetries for the cosmological field equations in brane-world
gravity with bulk scalar field | 14 pages, no figures, to appear in Physica Scripta | null | null | null | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | We address the group classification problem for gravitational field equations
within the context of brane-world cosmology, considering the presence of a bulk
scalar field. Our investigation revolves around a five-dimensional spacetime,
with the four-dimensional Friedmann--Lema\^{\i}tre--Robertson--Walker geometry
embedded within it. Additionally, we assume that the scalar field exists in
this five-dimensional geometry (bulk) and possesses a nonzero mass. The
resulting field equations constitute a system of nonlinear partial differential
equations. We apply the Lie symmetry condition to identify all functional forms
of the scalar field potential, ensuring that the field equations remain
invariant under one-parameter point transformations. Consequently, we find that
only the exponential potential exhibits Lie symmetries. Finally, the Lie
invariants are used to construct similarity transformations, which enable us to
derive exact solutions for the system.
| [
{
"created": "Mon, 9 Oct 2023 15:13:45 GMT",
"version": "v1"
}
] | 2023-10-10 | [
[
"Paliathanasis",
"Andronikos",
""
]
] | We address the group classification problem for gravitational field equations within the context of brane-world cosmology, considering the presence of a bulk scalar field. Our investigation revolves around a five-dimensional spacetime, with the four-dimensional Friedmann--Lema\^{\i}tre--Robertson--Walker geometry embedded within it. Additionally, we assume that the scalar field exists in this five-dimensional geometry (bulk) and possesses a nonzero mass. The resulting field equations constitute a system of nonlinear partial differential equations. We apply the Lie symmetry condition to identify all functional forms of the scalar field potential, ensuring that the field equations remain invariant under one-parameter point transformations. Consequently, we find that only the exponential potential exhibits Lie symmetries. Finally, the Lie invariants are used to construct similarity transformations, which enable us to derive exact solutions for the system. |
gr-qc/0005020 | Mohammad Vahid Takook | Mohammad Vahid Takook | Covariant two point function for minimally coupled scalar field in de
Sitter space-time | 7 pages, LaTex; some details added | Mod.Phys.Lett. A16 (2001) 1691-1698 | null | null | gr-qc | null | In a recent paper [1], it has been shown that negative norm states are
indispensable for a fully covariant quantization of the minimally coupled
scalar field in de Sitter space. Their presence, while leaving unchanged the
physical content of the theory, offers an automatic and covariant
renormalization of the vacuum energy divergence. This paper is a completion of
our previous work. An explicit construction of the covariant two-point function
of the ``massless'' minimally coupled scalar field in de Sitter space is given,
which is free of any infrared divergence. The associated Schwinger commutator
function and retarded Green's function are calculated in a fully gauge
invariant way, which also means coordinate independent.
| [
{
"created": "Mon, 8 May 2000 09:45:45 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Oct 2000 11:38:32 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Takook",
"Mohammad Vahid",
""
]
] | In a recent paper [1], it has been shown that negative norm states are indispensable for a fully covariant quantization of the minimally coupled scalar field in de Sitter space. Their presence, while leaving unchanged the physical content of the theory, offers an automatic and covariant renormalization of the vacuum energy divergence. This paper is a completion of our previous work. An explicit construction of the covariant two-point function of the ``massless'' minimally coupled scalar field in de Sitter space is given, which is free of any infrared divergence. The associated Schwinger commutator function and retarded Green's function are calculated in a fully gauge invariant way, which also means coordinate independent. |
2203.00385 | Umananda Dev Goswami | Pranjal Sarmah and Umananda Dev Goswami | Bianchi Type I model of universe with customized scale factors | 18 pages, 10 figures | Modern Physics Letters A (2022) | 10.1142/S0217732322501346 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | According to standard cosmology, the universe is homogeneous and isotropic at
large scales. However, some anisotropies can be observed at the local scale in
the universe through various ways. Here we have studied the Bianchi type I
model with customizing the scale factors to understand the anisotropic nature
of the universe. We have considered two cases with slight modifications of
scale factors in different directions in the generalized Bianchi Type I metric
equation, and compared the results with the $\Lambda$CDM model and also with
available cosmological observational data. Through this study, we also want to
predict the possible degree of anisotropy present in the early universe and its
evolution to current time by calculating the value of density parameter for
anisotropy ($\Omega_{\sigma}$) for both low and high redshift (z) along with
the possible relative anisotropy that exist among different directions. It is
found that there was a significant amount of anisotropy in the early universe
and the anisotropic nature of the universe vanishes at the near past and the
present epochs. Thus at near past and present stages of the universe there is
no effective distinction between this anisotropic model and the standard
$\Lambda$CDM model.
| [
{
"created": "Tue, 1 Mar 2022 12:10:22 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Sep 2022 08:17:53 GMT",
"version": "v2"
}
] | 2022-09-12 | [
[
"Sarmah",
"Pranjal",
""
],
[
"Goswami",
"Umananda Dev",
""
]
] | According to standard cosmology, the universe is homogeneous and isotropic at large scales. However, some anisotropies can be observed at the local scale in the universe through various ways. Here we have studied the Bianchi type I model with customizing the scale factors to understand the anisotropic nature of the universe. We have considered two cases with slight modifications of scale factors in different directions in the generalized Bianchi Type I metric equation, and compared the results with the $\Lambda$CDM model and also with available cosmological observational data. Through this study, we also want to predict the possible degree of anisotropy present in the early universe and its evolution to current time by calculating the value of density parameter for anisotropy ($\Omega_{\sigma}$) for both low and high redshift (z) along with the possible relative anisotropy that exist among different directions. It is found that there was a significant amount of anisotropy in the early universe and the anisotropic nature of the universe vanishes at the near past and the present epochs. Thus at near past and present stages of the universe there is no effective distinction between this anisotropic model and the standard $\Lambda$CDM model. |
gr-qc/0602083 | Tomohiro Inagaki | Tomohiro Inagaki | Radiative Symmetry Breaking and Dynamical Origin of Cosmological
Constant in $\phi^4$ Theory with Non-Linear Curvature Coupling | 9 pages. To appear in the proceedings of 7th Workshop on Quantum
Field Theory Under the Influence of External Conditions (QFEXT 05),
Barcelona, Catalonia, Spain, 5-9 Sep 2005 | J.Phys. A39 (2006) 6455-6462 | 10.1088/0305-4470/39/21/S41 | null | gr-qc | null | A scalar self-interacting theory non-linearly coupled with some power of the
curvature have a possibility to explain the current smallness of the
cosmological constant. Here one concentrate on a massless scalar field in the
four-dimensional Fridmann-Robertson-Walker (FRW) spacetime with flat spatial
part. One show the phase structure of radiative symmetry breaking and review a
dynamical resolution of the cosmological constant problem.
| [
{
"created": "Tue, 21 Feb 2006 14:23:35 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Inagaki",
"Tomohiro",
""
]
] | A scalar self-interacting theory non-linearly coupled with some power of the curvature have a possibility to explain the current smallness of the cosmological constant. Here one concentrate on a massless scalar field in the four-dimensional Fridmann-Robertson-Walker (FRW) spacetime with flat spatial part. One show the phase structure of radiative symmetry breaking and review a dynamical resolution of the cosmological constant problem. |
2007.09957 | Yungui Gong | Zhu Yi, Yungui Gong, Bin Wang, Zong-hong Zhu | Primordial black holes and secondary gravitational waves from the Higgs
field | added discussion on the running of the self-coupling, published in
PRD | Phys. Rev. D 103, 063535 (2021) | 10.1103/PhysRevD.103.063535 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We devise a novel mechanism and for the first time demonstrate that the Higgs
model in particle physics can drive the inflation to satisfy the cosmic
microwave background observations and simultaneously enhance the curvature
perturbations at small scales to explain the abundance of dark matter in our
universe in the form of primordial black holes. The production of primordial
black holes is accompanied by the secondary gravitational waves induced by the
first order Higgs fluctuations which is expected observable by space-based
gravitational wave detectors. We propose possible cosmological probes of Higgs
field in the future observations for primordial black holes dark matter or
stochastic gravitational waves.
| [
{
"created": "Mon, 20 Jul 2020 09:15:32 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Apr 2021 16:25:46 GMT",
"version": "v2"
}
] | 2021-04-07 | [
[
"Yi",
"Zhu",
""
],
[
"Gong",
"Yungui",
""
],
[
"Wang",
"Bin",
""
],
[
"Zhu",
"Zong-hong",
""
]
] | We devise a novel mechanism and for the first time demonstrate that the Higgs model in particle physics can drive the inflation to satisfy the cosmic microwave background observations and simultaneously enhance the curvature perturbations at small scales to explain the abundance of dark matter in our universe in the form of primordial black holes. The production of primordial black holes is accompanied by the secondary gravitational waves induced by the first order Higgs fluctuations which is expected observable by space-based gravitational wave detectors. We propose possible cosmological probes of Higgs field in the future observations for primordial black holes dark matter or stochastic gravitational waves. |
2403.09816 | David Gr\"uber | D. Gr\"uber, L. Sousa, P. P. Avelino | Stochastic gravitational wave background generated by domain wall
networks | null | null | null | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | In this work we study the power spectrum of the Stochastic Gravitational Wave
Background produced by standard and biased domain wall networks, using the
Velocity-dependent One-Scale model to compute the cosmological evolution of
their characteristic scale and root-mean-squared velocity. We consider a
standard radiation + $\Lambda \rm CDM$ background and assume that a constant
fraction of the energy of collapsing domain walls is emitted in the form of
gravitational waves. We show that, in an expanding background, the total energy
density in gravitational radiation decreases with cosmic time (after a short
initial period of quick growth). We also propose a two parameter model for the
scale-dependence of the frequency distribution of the gravitational waves
emitted by collapsing domain walls. We determine the corresponding power
spectrum of the Stochastic Gravitational Wave Background generated by domain
walls, showing that it is a monotonic decreasing function of the frequency for
frequencies larger than that of the peak generated by the walls that have
decayed most recently. We also develop an analytical approximation to this
spectrum, assuming perfect linear scaling during both the radiation and matter
eras, in order to characterize the dependence of the amplitude, peak frequency
and slope of the power spectrum on the model parameters.
| [
{
"created": "Thu, 14 Mar 2024 19:10:23 GMT",
"version": "v1"
}
] | 2024-03-18 | [
[
"Grüber",
"D.",
""
],
[
"Sousa",
"L.",
""
],
[
"Avelino",
"P. P.",
""
]
] | In this work we study the power spectrum of the Stochastic Gravitational Wave Background produced by standard and biased domain wall networks, using the Velocity-dependent One-Scale model to compute the cosmological evolution of their characteristic scale and root-mean-squared velocity. We consider a standard radiation + $\Lambda \rm CDM$ background and assume that a constant fraction of the energy of collapsing domain walls is emitted in the form of gravitational waves. We show that, in an expanding background, the total energy density in gravitational radiation decreases with cosmic time (after a short initial period of quick growth). We also propose a two parameter model for the scale-dependence of the frequency distribution of the gravitational waves emitted by collapsing domain walls. We determine the corresponding power spectrum of the Stochastic Gravitational Wave Background generated by domain walls, showing that it is a monotonic decreasing function of the frequency for frequencies larger than that of the peak generated by the walls that have decayed most recently. We also develop an analytical approximation to this spectrum, assuming perfect linear scaling during both the radiation and matter eras, in order to characterize the dependence of the amplitude, peak frequency and slope of the power spectrum on the model parameters. |
gr-qc/9612047 | Vladimir Dzhunushaliev | V.D. Dzhunushaliev | Multidimensional Geometrical Model of the Electrical and SU(2) Colour
Charge with Splitting off the Supplementary Coordinates | LATEX, p.7 | Russ.Phys.J. 41 (1998) 93-96; Izv.Vuz.Fiz. 41N2 (1998) 7-11 | null | null | gr-qc | null | The geometrical model of an electrical charge is proposed. This model has the
''nake'' charge shunted with ``fur - coat'' consisting of virtual wormholes.
The 5D wormhole solution in the Kaluza - Klein's theory is the ''nake'' charge.
The splitting off the supplementary coordinates happens on the two spheres
(null surfaces) bounding this 5D wormhole. This allows to sew two Reissner -
Nordstr\"om's black holes to it on both sides. Virtual wormholes entrap a part
of the electrical force lines outcoming from ''nake'' charge. This effect can
essentially decrease the charge visible at infinity up to real relation $m^2 <
e^2$. The analogical construction for colour SU(2) gauge charge is made.
| [
{
"created": "Mon, 16 Dec 1996 07:14:23 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Dzhunushaliev",
"V. D.",
""
]
] | The geometrical model of an electrical charge is proposed. This model has the ''nake'' charge shunted with ``fur - coat'' consisting of virtual wormholes. The 5D wormhole solution in the Kaluza - Klein's theory is the ''nake'' charge. The splitting off the supplementary coordinates happens on the two spheres (null surfaces) bounding this 5D wormhole. This allows to sew two Reissner - Nordstr\"om's black holes to it on both sides. Virtual wormholes entrap a part of the electrical force lines outcoming from ''nake'' charge. This effect can essentially decrease the charge visible at infinity up to real relation $m^2 < e^2$. The analogical construction for colour SU(2) gauge charge is made. |
1201.2667 | Alex Venditti | Alex Venditti, Charles Dyer | On the Response of Particle Detectors in Vaidya Spacetimes | 14 pages, 2 figures | Class. Quantum Grav. 30 (2013) 065004 | 10.1088/0264-9381/30/6/065004 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the formalism of the interaction picture we calculate an expression for
the Wightman function for only the spherically symmetric modes of a quantum
Klein-Gordon scalar field in a general Vaidya spacetime with ingoing null dust.
It is demonstrated that particle detectors following time-like trajectories
that are in the ground state at some time outside of the collapsing shell will
respond independently from the configuration of the ingoing null dust if the
response is taken at any time outside of the collapsing shell. For detectors
that are taken to be in the ground state at a time interior to the shell it is
shown that their response will depend on the configuration of the ingoing null
dust. Relevance to the information loss paradox is discussed.
| [
{
"created": "Thu, 12 Jan 2012 20:43:02 GMT",
"version": "v1"
}
] | 2013-03-06 | [
[
"Venditti",
"Alex",
""
],
[
"Dyer",
"Charles",
""
]
] | Using the formalism of the interaction picture we calculate an expression for the Wightman function for only the spherically symmetric modes of a quantum Klein-Gordon scalar field in a general Vaidya spacetime with ingoing null dust. It is demonstrated that particle detectors following time-like trajectories that are in the ground state at some time outside of the collapsing shell will respond independently from the configuration of the ingoing null dust if the response is taken at any time outside of the collapsing shell. For detectors that are taken to be in the ground state at a time interior to the shell it is shown that their response will depend on the configuration of the ingoing null dust. Relevance to the information loss paradox is discussed. |
2106.05163 | Atul Divakarla | Atul K. Divakarla, Bernard F. Whiting | The First-Order Velocity Memory Effect from Compact Binary Coalescing
Sources | null | Phys. Rev. D 104, 064001 (2021) | 10.1103/PhysRevD.104.064001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has long been known that gravitational waves from compact binary
coalescing sources are responsible for a first-order displacement memory effect
experienced by a pair of freely falling test masses. This constant displacement
is sourced from the non-vanishing final gravitational-wave strain present in
the wave's after-zone, often referred to as the non-linear memory effect, and
is of the same order of magnitude as the strain from the outgoing quadrupole
radiation. Hence, this prediction of general relativity is verifiable
experimentally by measurement of the final relative separation between test
masses that comprise gravitational-wave detectors. In a separate context,
independent calculations have demonstrated that exact, sandwich, plane wave
spacetimes exhibit a velocity memory effect: a non-zero relative velocity,
gained by a pair of test masses in free fall, after the passage of a
gravitational wave. In this paper, we find that in addition to the known
constant displacement memory effect test masses experience, a velocity memory
effect at leading order arises due to the non-linear nature of gravitational
waves from compact binary sources. We discuss the magnitude of the first-order
velocity memory effect in the context of observing gravitational-wave radiation
from super massive binary black hole mergers in LISA.
| [
{
"created": "Wed, 9 Jun 2021 16:10:56 GMT",
"version": "v1"
}
] | 2021-09-08 | [
[
"Divakarla",
"Atul K.",
""
],
[
"Whiting",
"Bernard F.",
""
]
] | It has long been known that gravitational waves from compact binary coalescing sources are responsible for a first-order displacement memory effect experienced by a pair of freely falling test masses. This constant displacement is sourced from the non-vanishing final gravitational-wave strain present in the wave's after-zone, often referred to as the non-linear memory effect, and is of the same order of magnitude as the strain from the outgoing quadrupole radiation. Hence, this prediction of general relativity is verifiable experimentally by measurement of the final relative separation between test masses that comprise gravitational-wave detectors. In a separate context, independent calculations have demonstrated that exact, sandwich, plane wave spacetimes exhibit a velocity memory effect: a non-zero relative velocity, gained by a pair of test masses in free fall, after the passage of a gravitational wave. In this paper, we find that in addition to the known constant displacement memory effect test masses experience, a velocity memory effect at leading order arises due to the non-linear nature of gravitational waves from compact binary sources. We discuss the magnitude of the first-order velocity memory effect in the context of observing gravitational-wave radiation from super massive binary black hole mergers in LISA. |
gr-qc/0607010 | Fabio Scardigli | Fabio Scardigli | Hawking temperature for various kinds of black holes from Heisenberg
uncertainty principle | LaTex file, 7 pages, 2 figures | Int. J. Geom. Meth. Mod. Phys., 2040004, 1 (2020) | 10.1142/S0219887820400046 | null | gr-qc | null | Hawking temperature is computed for a large class of black holes (with
spherical, toroidal and hyperboloidal topologies) using only laws of classical
physics plus the "classical" Heisenberg Uncertainty Principle. This principle
is shown to be fully sufficient to get the result, and there is no need to this
scope of a Generalized Uncertainty Principle.
| [
{
"created": "Tue, 4 Jul 2006 10:29:52 GMT",
"version": "v1"
}
] | 2020-04-17 | [
[
"Scardigli",
"Fabio",
""
]
] | Hawking temperature is computed for a large class of black holes (with spherical, toroidal and hyperboloidal topologies) using only laws of classical physics plus the "classical" Heisenberg Uncertainty Principle. This principle is shown to be fully sufficient to get the result, and there is no need to this scope of a Generalized Uncertainty Principle. |
0910.3887 | L\'aszl\'o \'A Gergely | L. \'A. Gergely, Z. Keresztes, A. Yu. Kamenshchik, V. Gorini, U.
Moschella | Do supernovae favor tachyonic Big Brake instead de Sitter? | 8 pages, 6 figures, to be published in the Proceedings of the
Invisible Universe International Conference, Paris, 2009, Ed. J. M. Alimi;
v2: references | AIP Conf.Proc.1241:884-891,2010 | 10.1063/1.3462729 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate whether a tachyonic scalar field, encompassing both dark
energy and dark matter-like features will drive our universe towards a Big
Brake singularity or a de Sitter expansion. In doing this it is crucial to
establish the parameter domain of the model, which is compatible with type Ia
supernovae data. We find the 1-sigma contours and evolve the tachyonic sytem
into the future. We conclude, that both future evolutions are allowed by
observations, Big Brake becoming increasingly likely with the increase of the
positive model parameter k.
| [
{
"created": "Tue, 20 Oct 2009 15:59:44 GMT",
"version": "v1"
},
{
"created": "Sun, 1 Nov 2009 06:53:36 GMT",
"version": "v2"
}
] | 2010-08-05 | [
[
"Gergely",
"L. Á.",
""
],
[
"Keresztes",
"Z.",
""
],
[
"Kamenshchik",
"A. Yu.",
""
],
[
"Gorini",
"V.",
""
],
[
"Moschella",
"U.",
""
]
] | We investigate whether a tachyonic scalar field, encompassing both dark energy and dark matter-like features will drive our universe towards a Big Brake singularity or a de Sitter expansion. In doing this it is crucial to establish the parameter domain of the model, which is compatible with type Ia supernovae data. We find the 1-sigma contours and evolve the tachyonic sytem into the future. We conclude, that both future evolutions are allowed by observations, Big Brake becoming increasingly likely with the increase of the positive model parameter k. |
1201.4048 | Naonori Sugiyama | Naonori S. Sugiyama | Consistency Relation for multifield inflation scenario with all loop
contributions | 24 pages, 6 figures | JCAP05(2012)032 | 10.1088/1475-7516/2012/05/032 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The consistency relation between non-linear parameters $f_{NL}$ and
$\tau_{NL}$ characterizing Non-Gaussianity generated during the inflationary
period have been emerged as a useful tool which have a possibility to rule out
a large class of inflationary models all at once. In our previous work, we
extended the Suyama-Yamaguchi inequality up to 1-loop corrections. In this
paper, we derive an inequality extended up to {\it all} loop corrections which
has the same expression with the original Suyama-Yamaguchi inequality,
$\tau_{NL} \geq (6/5f_{NL})^2$, where the equality is not satisfied in the case
of single field models any more.
| [
{
"created": "Thu, 19 Jan 2012 12:58:51 GMT",
"version": "v1"
},
{
"created": "Sun, 22 Jan 2012 13:16:34 GMT",
"version": "v2"
},
{
"created": "Tue, 24 Jan 2012 06:34:17 GMT",
"version": "v3"
},
{
"created": "Thu, 8 Mar 2012 09:01:53 GMT",
"version": "v4"
},
{
"created": "Wed, 11 Apr 2012 07:41:20 GMT",
"version": "v5"
},
{
"created": "Tue, 1 May 2012 07:34:15 GMT",
"version": "v6"
}
] | 2012-06-11 | [
[
"Sugiyama",
"Naonori S.",
""
]
] | The consistency relation between non-linear parameters $f_{NL}$ and $\tau_{NL}$ characterizing Non-Gaussianity generated during the inflationary period have been emerged as a useful tool which have a possibility to rule out a large class of inflationary models all at once. In our previous work, we extended the Suyama-Yamaguchi inequality up to 1-loop corrections. In this paper, we derive an inequality extended up to {\it all} loop corrections which has the same expression with the original Suyama-Yamaguchi inequality, $\tau_{NL} \geq (6/5f_{NL})^2$, where the equality is not satisfied in the case of single field models any more. |
1712.06533 | Serguei Ossokine | Serguei Ossokine, Tim Dietrich, Evan Foley, Reza Katebi, Geoffrey
Lovelace | Assessing the Energetics of Spinning Binary Black Hole Systems | null | Phys. Rev. D 98, 104057 (2018) | 10.1103/PhysRevD.98.104057 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we study the dynamics of spinning binary black hole systems in
the strong field regime. For this purpose we extract from numerical relativity
simulations the binding energy, specific orbital angular momentum, and
gauge-invariant orbital frequency. The goal of our work is threefold: First, we
extract the individual spin contributions to the binding energy, in particular
the spin-orbit, spin-spin, and cubic-in-spin terms. Second, we compare our
results with predictions from waveform models and find that while
post-Newtonian approximants are not capable of representing the dynamics during
the last few orbits before merger, there is good agreement between our data and
effective-one-body approximants as well as the numerical relativity surrogate
models. Finally, we present phenomenological representations for the binding
energy for non-spinning systems with mass ratios up to $q = 10$ and for the
spin-orbit interaction for mass ratios up to $q = 8$ obtaining accuracies of
$\lesssim 0.1\%$ and $\lesssim 6\%$, respectively.
| [
{
"created": "Mon, 18 Dec 2017 17:20:11 GMT",
"version": "v1"
}
] | 2018-12-05 | [
[
"Ossokine",
"Serguei",
""
],
[
"Dietrich",
"Tim",
""
],
[
"Foley",
"Evan",
""
],
[
"Katebi",
"Reza",
""
],
[
"Lovelace",
"Geoffrey",
""
]
] | In this work we study the dynamics of spinning binary black hole systems in the strong field regime. For this purpose we extract from numerical relativity simulations the binding energy, specific orbital angular momentum, and gauge-invariant orbital frequency. The goal of our work is threefold: First, we extract the individual spin contributions to the binding energy, in particular the spin-orbit, spin-spin, and cubic-in-spin terms. Second, we compare our results with predictions from waveform models and find that while post-Newtonian approximants are not capable of representing the dynamics during the last few orbits before merger, there is good agreement between our data and effective-one-body approximants as well as the numerical relativity surrogate models. Finally, we present phenomenological representations for the binding energy for non-spinning systems with mass ratios up to $q = 10$ and for the spin-orbit interaction for mass ratios up to $q = 8$ obtaining accuracies of $\lesssim 0.1\%$ and $\lesssim 6\%$, respectively. |
0904.3627 | Gil Jannes | Gil Jannes | Condensed matter lessons about the origin of time | v1: 9 pages. Fourth juried prize in FQXi essay contest on "the Nature
of Time" (2008). v2: 2015 update, partially rewritten and extended for
Foundations of Physics. arXiv admin note: substantial text overlap with
arXiv:0810.0613 | Found. Phys. 45, 279-294 (2015) | 10.1007/s10701-014-9864-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is widely hoped that quantum gravity will shed light on the question of
the origin of time in physics. The currently dominant approaches to a candidate
quantum theory of gravity have naturally evolved from general relativity, on
the one hand, and from particle physics, on the other hand. A third important
branch of 20th century `fundamental' physics, condensed-matter physics, also
offers an interesting perspective on quantum gravity, and thereby on the
problem of time. The bottomline might sound disappointing: to understand the
origin of time, much more experimental input is needed than what is available
today. Moreover it is far from obvious that we will ever find out the true
origin of physical time, even if we become able to directly probe physics at
the Planck scale. But we might learn some interesting lessons about time and
the structure of our universe in the process. A first lesson is that there are
probably several characteristic scales associated with "quantum gravity"
effects, rather than the single Planck scale usually considered. These can
differ by several orders of magnitude, and thereby conspire to hide certain
effects expected from quantum gravity, rendering them undetectable even with
Planck-scale experiments. A more tentative conclusion is that the hierarchy
between general relativity, special relativity and Newtonian physics, usually
taken for granted, might have to be interpreted with caution.
| [
{
"created": "Thu, 23 Apr 2009 08:41:09 GMT",
"version": "v1"
},
{
"created": "Wed, 13 May 2015 16:46:04 GMT",
"version": "v2"
}
] | 2015-05-14 | [
[
"Jannes",
"Gil",
""
]
] | It is widely hoped that quantum gravity will shed light on the question of the origin of time in physics. The currently dominant approaches to a candidate quantum theory of gravity have naturally evolved from general relativity, on the one hand, and from particle physics, on the other hand. A third important branch of 20th century `fundamental' physics, condensed-matter physics, also offers an interesting perspective on quantum gravity, and thereby on the problem of time. The bottomline might sound disappointing: to understand the origin of time, much more experimental input is needed than what is available today. Moreover it is far from obvious that we will ever find out the true origin of physical time, even if we become able to directly probe physics at the Planck scale. But we might learn some interesting lessons about time and the structure of our universe in the process. A first lesson is that there are probably several characteristic scales associated with "quantum gravity" effects, rather than the single Planck scale usually considered. These can differ by several orders of magnitude, and thereby conspire to hide certain effects expected from quantum gravity, rendering them undetectable even with Planck-scale experiments. A more tentative conclusion is that the hierarchy between general relativity, special relativity and Newtonian physics, usually taken for granted, might have to be interpreted with caution. |
2302.00529 | Jo\'as Ven\^ancio | Jo\'as Ven\^ancio | On the quasinormal modes in generalized Nariai spacetimes | 114 pages, 7 figures. arXiv admin note: text overlap with
arXiv:1804.05953 | This PhD thesis was published as a book by Lambert Academic
Publishing (2021). ISBN: 978-6203840384 | null | null | gr-qc hep-th math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | Quasinormal modes are eigenmodes of dissipative systems. For instance, if a
spacetime with an event or cosmological horizon is perturbed from its
equilibrium state, quasinormal modes arise as damped oscillations with a
spectrum of complex frequencies, called quasinormal frequencies, that depends
just on the charges which define the geometry of the spacetime in which the
perturbation is propagating, such as the mass, electric charge, and angular
momentum. Mathematically, this discrete spectrum of quasinormal modes stems
from the fact that certain boundary conditions must be imposed to the physical
fields propagating in such a spacetime. In this thesis, we shall consider a
higher-dimensional generalization of the charged Nariai spacetime that is
comprised of the direct product of the two-dimensional de Sitter space, $dS_2$,
with an arbitrary number of two-spheres, $S^2$, and investigate the dynamics of
spin-$s$ field perturbations for $s = 0, 1/2, 1$ and $2$. The boundary
conditions leading to quasinormal modes are analyzed and the quasinormal
frequencies are analytically obtained.
| [
{
"created": "Wed, 1 Feb 2023 15:57:43 GMT",
"version": "v1"
}
] | 2023-02-02 | [
[
"Venâncio",
"Joás",
""
]
] | Quasinormal modes are eigenmodes of dissipative systems. For instance, if a spacetime with an event or cosmological horizon is perturbed from its equilibrium state, quasinormal modes arise as damped oscillations with a spectrum of complex frequencies, called quasinormal frequencies, that depends just on the charges which define the geometry of the spacetime in which the perturbation is propagating, such as the mass, electric charge, and angular momentum. Mathematically, this discrete spectrum of quasinormal modes stems from the fact that certain boundary conditions must be imposed to the physical fields propagating in such a spacetime. In this thesis, we shall consider a higher-dimensional generalization of the charged Nariai spacetime that is comprised of the direct product of the two-dimensional de Sitter space, $dS_2$, with an arbitrary number of two-spheres, $S^2$, and investigate the dynamics of spin-$s$ field perturbations for $s = 0, 1/2, 1$ and $2$. The boundary conditions leading to quasinormal modes are analyzed and the quasinormal frequencies are analytically obtained. |
gr-qc/0511091 | Jerry B. Griffiths | J. B. Griffiths and J. Podolsky | A new look at the Plebanski-Demianski family of solutions | 33 pages, 2 figures. To appear in Int. J. Mod. Phys. D | Int.J.Mod.Phys. D15 (2006) 335-370 | 10.1142/S0218271806007742 | null | gr-qc | null | The Plebanski-Demianski metric, and those that can be obtained from it by
taking coordinate transformations in certain limits, include the complete
family of space-times of type D with an aligned electromagnetic field and a
possibly non-zero cosmological constant. Starting with a new form of the line
element which is better suited both for physical interpretation and for
identifying different subfamilies, we review this entire family of solutions.
Our metric for the expanding case explicitly includes two parameters which
represent the acceleration of the sources and the twist of the repeated
principal null congruences, the twist being directly related to both the
angular velocity of the sources and their NUT-like properties. The
non-expanding type D solutions are also identified. All special cases are
derived in a simple and transparent way.
| [
{
"created": "Wed, 16 Nov 2005 17:24:27 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Griffiths",
"J. B.",
""
],
[
"Podolsky",
"J.",
""
]
] | The Plebanski-Demianski metric, and those that can be obtained from it by taking coordinate transformations in certain limits, include the complete family of space-times of type D with an aligned electromagnetic field and a possibly non-zero cosmological constant. Starting with a new form of the line element which is better suited both for physical interpretation and for identifying different subfamilies, we review this entire family of solutions. Our metric for the expanding case explicitly includes two parameters which represent the acceleration of the sources and the twist of the repeated principal null congruences, the twist being directly related to both the angular velocity of the sources and their NUT-like properties. The non-expanding type D solutions are also identified. All special cases are derived in a simple and transparent way. |
gr-qc/0305086 | Maria da Conceicao Bento | M.C. Bento, O. Bertolami and A.A. Sen | Generalized Chaplygin Gas Model: Dark Energy - Dark Matter Unification
and CMBR Constraints | 9 pages, 2 figures; essay selected for an honorable mention by the
Gravity Research Foundation, 2003 | Gen.Rel.Grav.35:2063-2069,2003 | 10.1023/A:1026207312105 | null | gr-qc | null | The generalized Chaplygin gas (GCG) model allows for an unified description
of the recent accelerated expansion of the Universe and the evolution of energy
density perturbations. This dark energy - dark matter unification is achieved
through an exotic background fluid whose equation of state is given by $p = -
A/\rho^{\alpha}$, where $A$ is a positive constant and $0 < \alpha \le 1$.
Stringent constraints on the model parameters can be obtained from recent WMAP
and BOOMERanG bounds on the locations of the first few peaks and troughs of the
Cosmic Microwave Background Radiation (CMBR) power spectrum as well as SNe Ia
data.
| [
{
"created": "Thu, 22 May 2003 14:47:16 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Bento",
"M. C.",
""
],
[
"Bertolami",
"O.",
""
],
[
"Sen",
"A. A.",
""
]
] | The generalized Chaplygin gas (GCG) model allows for an unified description of the recent accelerated expansion of the Universe and the evolution of energy density perturbations. This dark energy - dark matter unification is achieved through an exotic background fluid whose equation of state is given by $p = - A/\rho^{\alpha}$, where $A$ is a positive constant and $0 < \alpha \le 1$. Stringent constraints on the model parameters can be obtained from recent WMAP and BOOMERanG bounds on the locations of the first few peaks and troughs of the Cosmic Microwave Background Radiation (CMBR) power spectrum as well as SNe Ia data. |
1904.09713 | Nikolaos Dimakis | N. Dimakis, A. Paliathanasis, Petros A. Terzis and T. Christodoulakis | Cosmological Solutions in Multiscalar Field Theory | 15 pages, 3 figures, Latex2e source file, revised to agree with the
accepted EPJC version | null | 10.1140/epjc/s10052-019-7130-8 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a cosmological model with two scalar fields minimally coupled to
gravity which have a mixed kinetic term. Hence, Chiral cosmology is included in
our analysis. The coupling function and the potential function, which depend on
one of the fields, characterize the model we study. We prove the existence of
exact solutions that are of special interest for the cosmological evolution.
Furthermore, we provide with a methodology that relates the scale factor
behaviour to the free functions characterizing the scalar field kinetic term
coupling and potential. We derive the necessary conditions that connect these
two functions so that the relative cosmological solutions can be admitted. We
find that unified dark matter and dark energy solutions are allowed by the
theory in various scenarios involving the aforementioned functions.
| [
{
"created": "Mon, 22 Apr 2019 03:55:29 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Jul 2019 01:22:46 GMT",
"version": "v2"
}
] | 2019-09-04 | [
[
"Dimakis",
"N.",
""
],
[
"Paliathanasis",
"A.",
""
],
[
"Terzis",
"Petros A.",
""
],
[
"Christodoulakis",
"T.",
""
]
] | We consider a cosmological model with two scalar fields minimally coupled to gravity which have a mixed kinetic term. Hence, Chiral cosmology is included in our analysis. The coupling function and the potential function, which depend on one of the fields, characterize the model we study. We prove the existence of exact solutions that are of special interest for the cosmological evolution. Furthermore, we provide with a methodology that relates the scale factor behaviour to the free functions characterizing the scalar field kinetic term coupling and potential. We derive the necessary conditions that connect these two functions so that the relative cosmological solutions can be admitted. We find that unified dark matter and dark energy solutions are allowed by the theory in various scenarios involving the aforementioned functions. |
1705.06941 | Arpita Mitra | Rabin Banerjee, Sumanta Chakraborty, Arpita Mitra, Pradip Mukherjee | Cosmological implications of shift symmetric Galileon field | Revised Version; Accepted in PRD; 20 pages; 1 figure | Phys. Rev. D 96, 064023 (2017) | 10.1103/PhysRevD.96.064023 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A ghost-free metric formulation of the recently proposed covariant Galileon
model \cite{RPgal} which retains the internal shift symmetry has been
constructed. This presents a new result because the covariant Galileon models
introduced so far in the literature lacks the full Galileon symmetry. We
demonstrate that the same general procedure is applicable to all the Galileon
interaction terms and the resulting ghost-free Galileon action respecting
internal shift symmetry cannot predict the late time acceleration of the
universe. However, weakly breaking the shift symmetry in the covariant Galileon
Lagrangian, allows us to include an appropriate potential term which can
explain late time acceleration, in accordance with recent findings in the
literature.
| [
{
"created": "Fri, 19 May 2017 11:32:20 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Aug 2017 16:07:15 GMT",
"version": "v2"
}
] | 2017-09-20 | [
[
"Banerjee",
"Rabin",
""
],
[
"Chakraborty",
"Sumanta",
""
],
[
"Mitra",
"Arpita",
""
],
[
"Mukherjee",
"Pradip",
""
]
] | A ghost-free metric formulation of the recently proposed covariant Galileon model \cite{RPgal} which retains the internal shift symmetry has been constructed. This presents a new result because the covariant Galileon models introduced so far in the literature lacks the full Galileon symmetry. We demonstrate that the same general procedure is applicable to all the Galileon interaction terms and the resulting ghost-free Galileon action respecting internal shift symmetry cannot predict the late time acceleration of the universe. However, weakly breaking the shift symmetry in the covariant Galileon Lagrangian, allows us to include an appropriate potential term which can explain late time acceleration, in accordance with recent findings in the literature. |
gr-qc/0606004 | Edward Malec | Bogusz Kinasiewicz, Patryk Mach and Edward Malec | Selfgravitation in a general-relativistic accretion of steady fluids | Typos corrected. Talk given at the 42nd Karpacz Winter School of
Theoretical Physics, Ladek, Poland February 2006 on Current Mathematical
Topics in Gravitation and Cosmology | Int.J.Geom.Meth.Mod.Phys.4:197-208,2007 | 10.1142/S0219887807001953 | null | gr-qc | null | The selfgravity of an infalling gas can alter significantly the accretion of
gases. In the case of spherically symmetric steady flows of polytropic perfect
fluids the mass accretion rate achieves maximal value when the mass of the
fluid is 1/3 of the total mass. There are two weakly accreting regimes, one
over-abundant and the other poor in fluid content. The analysis within the
newtonian gravity suggests that selfgravitating fluids can be unstable, in
contrast to the accretion of test fluids.
| [
{
"created": "Thu, 1 Jun 2006 17:23:07 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Jun 2006 11:23:37 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Kinasiewicz",
"Bogusz",
""
],
[
"Mach",
"Patryk",
""
],
[
"Malec",
"Edward",
""
]
] | The selfgravity of an infalling gas can alter significantly the accretion of gases. In the case of spherically symmetric steady flows of polytropic perfect fluids the mass accretion rate achieves maximal value when the mass of the fluid is 1/3 of the total mass. There are two weakly accreting regimes, one over-abundant and the other poor in fluid content. The analysis within the newtonian gravity suggests that selfgravitating fluids can be unstable, in contrast to the accretion of test fluids. |
2302.14653 | Th. M. Nieuwenhuizen | Theodorus Maria Nieuwenhuizen | Exact solutions for black holes with a smooth quantum core | 29 pages, 8 figures | null | null | null | gr-qc astro-ph.GA | http://creativecommons.org/licenses/by-nc-nd/4.0/ | A class of exact solutions are presented for the interior of black holes of
solar mass and beyond. In a core enclosed by the inner horizon, the binding
energy released by dissolution of the pre-collapse nuclei is stored in
electrostatic and zero point energy. Gravitational collapse is prevented by
their negative pressures. In the mantle, the region between the inner and event
horizons, there is a standard vacuum. Accounting for the rest masses of the up
and down quarks and electrons leads to corrections at the per cent level.
Spherically symmetric fluctuations have a spectrum without unstable modes. A
surface layer with a charge current can be present on the outer side of the
inner horizon; a layer of opposite charges on the event horizon can make an
extremely charged black hole neutral. Merging of an extremal black hole with
another extremal one or with a neutron star may produce electromagnetic
fireworks.
| [
{
"created": "Mon, 27 Feb 2023 18:09:42 GMT",
"version": "v1"
}
] | 2023-03-01 | [
[
"Nieuwenhuizen",
"Theodorus Maria",
""
]
] | A class of exact solutions are presented for the interior of black holes of solar mass and beyond. In a core enclosed by the inner horizon, the binding energy released by dissolution of the pre-collapse nuclei is stored in electrostatic and zero point energy. Gravitational collapse is prevented by their negative pressures. In the mantle, the region between the inner and event horizons, there is a standard vacuum. Accounting for the rest masses of the up and down quarks and electrons leads to corrections at the per cent level. Spherically symmetric fluctuations have a spectrum without unstable modes. A surface layer with a charge current can be present on the outer side of the inner horizon; a layer of opposite charges on the event horizon can make an extremely charged black hole neutral. Merging of an extremal black hole with another extremal one or with a neutron star may produce electromagnetic fireworks. |
1306.1489 | Eyo Ita III | Ching-Yi Chou, Eyo Ita, Chopin Soo | Affine group formulation of the Standard Model coupled to gravity | 9 pages | Annals of Physics 343 (2014), pp. 153-163 | 10.1016/j.aop.2014.01.017 | REP12 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work demonstrates that a complete description of the interaction of
matter and all forces, gravitational and non-gravitational, can in fact be
realized within a quantum affine algebraic framework. Using the affine group
formalism, we construct elements of a physical Hilbert space for full,
Lorentzian quantum gravity coupled to the Standard Model in four spacetime
dimensions. Affine algebraic quantization of gravitation and matter on equal
footing implies a fundamental uncertainty relation which is predicated upon a
non-vanishing cosmological constant.
| [
{
"created": "Thu, 6 Jun 2013 17:49:53 GMT",
"version": "v1"
},
{
"created": "Sat, 8 Jun 2013 19:17:26 GMT",
"version": "v2"
},
{
"created": "Fri, 31 Jan 2014 12:59:36 GMT",
"version": "v3"
},
{
"created": "Thu, 13 Mar 2014 12:50:41 GMT",
"version": "v4"
}
] | 2015-06-16 | [
[
"Chou",
"Ching-Yi",
""
],
[
"Ita",
"Eyo",
""
],
[
"Soo",
"Chopin",
""
]
] | This work demonstrates that a complete description of the interaction of matter and all forces, gravitational and non-gravitational, can in fact be realized within a quantum affine algebraic framework. Using the affine group formalism, we construct elements of a physical Hilbert space for full, Lorentzian quantum gravity coupled to the Standard Model in four spacetime dimensions. Affine algebraic quantization of gravitation and matter on equal footing implies a fundamental uncertainty relation which is predicated upon a non-vanishing cosmological constant. |
2105.05047 | Fatemeh Naeimipour | Behrouz Mirza, Fatemeh Naeimipour and Masoumeh Tavakoli | Joule-Thomson expansion of the quasitopological black holes | 14 pages,8 figures,53 Reference | Frontiers in Physics 9 (2021) 628727 | 10.3389/fphy.2021.628727 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate the thermal stability and Joule-Thomson
expansion of some new qusitopological black hole solutions. We first study the
higher-dimensional static quasitopological black hole solutions in the presence
of Born-Infeld, exponential and logarithmic nonlinear electrodynamics. The
stable regions of these solutions are independent of the types of the nonlinear
electrodynamics. The solutions with the horizons relating to the positive
constant curvature, $k=+1$, have a larger region in thermal stability, if we
choose positive quasitopological coefficients, $\mu_{i}>0$. We also have a
review on the power Maxwell quasitopological black hole. Then, we obtain the
five-dimensional Yang-Mills quasitopological black hole solution and compare
with the quasitopological Maxwell solution. For large values of the electric
charge, $q$, and the Yang-Mills charge, $e$, we showed that the stable range of
the Maxwell quasitopological black hole is larger than the Yang-Mills one. This
is while thermal stability for small charges has the same behavior for these
black holes. In the following, we obtain the thermodynamic quantities for these
solutions and then study the Joule-Thomson expansion. We consider the
temperature changes in an isenthalpy process during this expansion. The
obtained results show that the inversion curves can divide the isenthalpic ones
into two parts in the inversion pressure, $P_{i}$. For $P<P_{i}$, a cooling
phenomena with positive slope happens in $T-P$ diagram, while there is a
heating process with negative slope for $P>P_{i}$. As the values of the
nonlinear parameter, $\beta$, the electric and Yang-Mills charges decrease, the
temperature goes to zero with a small slope and so the heating phenomena
happens slowly.
| [
{
"created": "Sun, 9 May 2021 16:49:31 GMT",
"version": "v1"
}
] | 2021-05-13 | [
[
"Mirza",
"Behrouz",
""
],
[
"Naeimipour",
"Fatemeh",
""
],
[
"Tavakoli",
"Masoumeh",
""
]
] | In this paper, we investigate the thermal stability and Joule-Thomson expansion of some new qusitopological black hole solutions. We first study the higher-dimensional static quasitopological black hole solutions in the presence of Born-Infeld, exponential and logarithmic nonlinear electrodynamics. The stable regions of these solutions are independent of the types of the nonlinear electrodynamics. The solutions with the horizons relating to the positive constant curvature, $k=+1$, have a larger region in thermal stability, if we choose positive quasitopological coefficients, $\mu_{i}>0$. We also have a review on the power Maxwell quasitopological black hole. Then, we obtain the five-dimensional Yang-Mills quasitopological black hole solution and compare with the quasitopological Maxwell solution. For large values of the electric charge, $q$, and the Yang-Mills charge, $e$, we showed that the stable range of the Maxwell quasitopological black hole is larger than the Yang-Mills one. This is while thermal stability for small charges has the same behavior for these black holes. In the following, we obtain the thermodynamic quantities for these solutions and then study the Joule-Thomson expansion. We consider the temperature changes in an isenthalpy process during this expansion. The obtained results show that the inversion curves can divide the isenthalpic ones into two parts in the inversion pressure, $P_{i}$. For $P<P_{i}$, a cooling phenomena with positive slope happens in $T-P$ diagram, while there is a heating process with negative slope for $P>P_{i}$. As the values of the nonlinear parameter, $\beta$, the electric and Yang-Mills charges decrease, the temperature goes to zero with a small slope and so the heating phenomena happens slowly. |
1106.1805 | Scott Robertson | Scott James Robertson | Hawking Radiation in Dispersive Media | PhD thesis, 221 pages, 53 figures | null | null | null | gr-qc physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Hawking radiation, despite its presence in theoretical physics for over
thirty years, remains elusive and undetected. It also suffers, in its original
context of gravitational black holes, from conceptual difficulties. Of
particular note is the trans-Planckian problem, which is concerned with the
apparent origin of the radiation in absurdly high frequencies. In order to gain
better theoretical understanding and, it is hoped, experimental verification of
Hawking radiation, much study is being devoted to systems which model the
spacetime geometry of black holes, and which, by analogy, are also thought to
emit Hawking radiation. These analogue systems typically exhibit dispersion,
which regularizes the wave behaviour at the horizon but does not lend itself
well to analytic treatment, thus rendering Hawking's prediction less secure. A
general analytic method for dealing with Hawking radiation in dispersive
systems has proved difficult to find.
This thesis presents new numerical and analytic results for Hawking emission
spectra in dispersive systems. It examines two black-hole analogue systems: it
begins by introducing the well-known acoustic model, presenting some original
results in that context; then, through analogy with the acoustic model, goes on
to develop the lesser-known fibre-optical model.
| [
{
"created": "Thu, 9 Jun 2011 13:27:30 GMT",
"version": "v1"
}
] | 2011-06-10 | [
[
"Robertson",
"Scott James",
""
]
] | Hawking radiation, despite its presence in theoretical physics for over thirty years, remains elusive and undetected. It also suffers, in its original context of gravitational black holes, from conceptual difficulties. Of particular note is the trans-Planckian problem, which is concerned with the apparent origin of the radiation in absurdly high frequencies. In order to gain better theoretical understanding and, it is hoped, experimental verification of Hawking radiation, much study is being devoted to systems which model the spacetime geometry of black holes, and which, by analogy, are also thought to emit Hawking radiation. These analogue systems typically exhibit dispersion, which regularizes the wave behaviour at the horizon but does not lend itself well to analytic treatment, thus rendering Hawking's prediction less secure. A general analytic method for dealing with Hawking radiation in dispersive systems has proved difficult to find. This thesis presents new numerical and analytic results for Hawking emission spectra in dispersive systems. It examines two black-hole analogue systems: it begins by introducing the well-known acoustic model, presenting some original results in that context; then, through analogy with the acoustic model, goes on to develop the lesser-known fibre-optical model. |
1605.09094 | Miguel Campiglia | Miguel Campiglia, Alok Laddha | Sub-subleading soft gravitons: New symmetries of quantum gravity? | 5 pages | null | 10.1016/j.physletb.2016.11.046 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Due to seminal works of Weinberg, Cachazo and Strominger we know that tree
level quantum gravity amplitudes satisfy three factorization constraints.
Building on previous works which relate two of these constraints to symmetries
of quantum gravity at null infinity, we present rather strong evidence that the
third constraint is also equivalent to a new set of symmetries of
(perturbative) quantum gravity. Our analysis implies that the symmetry group of
quantum gravity may be even richer than the BMS group (or infinite dimensional
extension thereof) previously considered.
| [
{
"created": "Mon, 30 May 2016 03:37:04 GMT",
"version": "v1"
}
] | 2017-02-01 | [
[
"Campiglia",
"Miguel",
""
],
[
"Laddha",
"Alok",
""
]
] | Due to seminal works of Weinberg, Cachazo and Strominger we know that tree level quantum gravity amplitudes satisfy three factorization constraints. Building on previous works which relate two of these constraints to symmetries of quantum gravity at null infinity, we present rather strong evidence that the third constraint is also equivalent to a new set of symmetries of (perturbative) quantum gravity. Our analysis implies that the symmetry group of quantum gravity may be even richer than the BMS group (or infinite dimensional extension thereof) previously considered. |
gr-qc/0403107 | Alexander Poltorak | Alexander Poltorak | On the Energy Problem in General Relativity | 6 pages, LaTeX, GR10 Abstract (1983) | 10th International Conference on General Relativity and
Gravitation, Padova, 1983, Contributed Papers, Ed.: B. Bertotti, F. de
Felice, A. Pascolini. Vol.1, p. 609 | null | null | gr-qc | null | The Energy Problem (EP) in General Relativity (GR) is analyzed in the context
of GR's axiomatic inconsistencies. EP is classified according to its local and
global aspects. The local aspects of the EP include noncovariance of the
energy-momentum pseudotensor (EMPT) of the gravitational field, non-uniqueness
of the EMPT, asymmetry of EMPT, and vanishing metric energy-momentum tensor.
The global aspect of the EP relates to the lack of integral conservation laws
due to the general difficulties in defining invariant integrals of tensors in
non-Euclidean space. These difficulties are related to the lack of precise
definition of a reference frame in the GR. A reference frame is defined here as
a differential manifold with an affine connection. The resulting unique
decomposition of the Levi-Civita connection into its affine and nonmetric parts
allows for a covariant definition of the gravitational energy-momentum tensor.
It is pointed out that the invariance of the Lagrangian (or action functional)
is a necessary but not sufficient condition to secure the covariance of the
Lagrange-Euler field theory. A rigorous definition of the Lagrange Field
Structure (LFS) on differential manifolds is proposed. A covariant
generalization of the first Noether theorem for LFS is obtained. Different
approaches to the EP are discussed.
| [
{
"created": "Thu, 25 Mar 2004 23:19:27 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Poltorak",
"Alexander",
""
]
] | The Energy Problem (EP) in General Relativity (GR) is analyzed in the context of GR's axiomatic inconsistencies. EP is classified according to its local and global aspects. The local aspects of the EP include noncovariance of the energy-momentum pseudotensor (EMPT) of the gravitational field, non-uniqueness of the EMPT, asymmetry of EMPT, and vanishing metric energy-momentum tensor. The global aspect of the EP relates to the lack of integral conservation laws due to the general difficulties in defining invariant integrals of tensors in non-Euclidean space. These difficulties are related to the lack of precise definition of a reference frame in the GR. A reference frame is defined here as a differential manifold with an affine connection. The resulting unique decomposition of the Levi-Civita connection into its affine and nonmetric parts allows for a covariant definition of the gravitational energy-momentum tensor. It is pointed out that the invariance of the Lagrangian (or action functional) is a necessary but not sufficient condition to secure the covariance of the Lagrange-Euler field theory. A rigorous definition of the Lagrange Field Structure (LFS) on differential manifolds is proposed. A covariant generalization of the first Noether theorem for LFS is obtained. Different approaches to the EP are discussed. |
1707.08179 | Massimo Giovannini | Massimo Giovannini | Squeezed relic photons beyond the horizon | 33 pages. arXiv admin note: text overlap with arXiv:1608.05843 | Phys. Rev. D 96, 103513 (2017) | 10.1103/PhysRevD.96.103513 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Owing to the analogy with the ordinary photons in the visible range of the
electromagnetic spectrum, the Glauber theory is generalized to address the
quantum coherence of the gauge field fluctuations parametrically amplified
during an inflationary stage of expansion. The first and second degrees of
quantum coherence of relic photons are then computed beyond the effective
horizon defined by the evolution of the susceptibility. In the zero-delay limit
the Hanbury Brown-Twiss correlations exhibit a super-Poissonian statistics
which is however different from the conventional results of the single-mode
approximation customarily employed, in quantum optics, to classify the
coherence properties of visible light. While in the case of large-scale
curvature perturbations the degrees of quantum coherence coincide with the
naive expectation of the single-mode approximation, the net degree of
second-order coherence computed for the relic photons diminishes thanks to the
effect of the polarizations. We suggest that the Hanbury Brown-twiss
correlations are probably the only tool to assess the quantum or classical
origin of the large-scale magnetic fluctuations and of the corresponding
curvature perturbations.
| [
{
"created": "Sat, 22 Jul 2017 14:08:54 GMT",
"version": "v1"
}
] | 2017-11-20 | [
[
"Giovannini",
"Massimo",
""
]
] | Owing to the analogy with the ordinary photons in the visible range of the electromagnetic spectrum, the Glauber theory is generalized to address the quantum coherence of the gauge field fluctuations parametrically amplified during an inflationary stage of expansion. The first and second degrees of quantum coherence of relic photons are then computed beyond the effective horizon defined by the evolution of the susceptibility. In the zero-delay limit the Hanbury Brown-Twiss correlations exhibit a super-Poissonian statistics which is however different from the conventional results of the single-mode approximation customarily employed, in quantum optics, to classify the coherence properties of visible light. While in the case of large-scale curvature perturbations the degrees of quantum coherence coincide with the naive expectation of the single-mode approximation, the net degree of second-order coherence computed for the relic photons diminishes thanks to the effect of the polarizations. We suggest that the Hanbury Brown-twiss correlations are probably the only tool to assess the quantum or classical origin of the large-scale magnetic fluctuations and of the corresponding curvature perturbations. |
2209.08748 | Mark Klehfoth | Mark G. Klehfoth and Robert M. Wald | Local and Covariant Flow Relations for OPE Coefficients in Lorentzian
Spacetimes | 115 pages, 1 figure (shortened abstract; full abstract in paper) | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For Euclidean quantum field theories, Holland and Hollands have shown
operator product expansion (OPE) coefficients satisfy "flow equations": For
interaction parameter $\lambda$, the partial derivative of any OPE coefficient
with respect to $\lambda$ is given by an integral over Euclidean space of a sum
of products of other OPE coefficients. In this paper, we generalize these
results for flat Euclidean space to curved Lorentzian spacetimes in the context
of the solvable "toy model" of massive Klein-Gordon scalar field theory, with
$m^2$ viewed as the "self-interaction parameter". Even in Minkowski spacetime,
a serious difficulty arises from the fact that all integrals must be taken over
a compact spacetime region to ensure convergence but any integration cutoff
necessarily breaks Lorentz covariance. We show how covariant flow relations can
be obtained by adding compensating "counterterms" in a manner similar to that
of the Epstein-Glaser renormalization scheme. We also show how to eliminate
dependence on the "infrared-cutoff scale" $L$, thereby yielding flow relations
compatible with almost homogeneous scaling of the fields. In curved spacetime,
the spacetime integration will cause the OPE coefficients to depend non-locally
on the spacetime metric, in violation of the requirement that quantum fields
should depend locally and covariantly on the metric. We show how this
potentially serious difficulty can be overcome by replacing the metric with a
suitable local polynomial approximation about the OPE expansion point. We
thereby obtain local and covariant flow relations for the OPE coefficients of
Klein-Gordon theory in curved Lorentzian spacetimes. In an appendix, we develop
an algorithm for constructing local and covariant flow relations beyond our
"toy model" based on the associativity properties of OPE coefficients, and we
apply our method to $\lambda\phi^4$-theory.
| [
{
"created": "Mon, 19 Sep 2022 03:59:08 GMT",
"version": "v1"
}
] | 2022-09-20 | [
[
"Klehfoth",
"Mark G.",
""
],
[
"Wald",
"Robert M.",
""
]
] | For Euclidean quantum field theories, Holland and Hollands have shown operator product expansion (OPE) coefficients satisfy "flow equations": For interaction parameter $\lambda$, the partial derivative of any OPE coefficient with respect to $\lambda$ is given by an integral over Euclidean space of a sum of products of other OPE coefficients. In this paper, we generalize these results for flat Euclidean space to curved Lorentzian spacetimes in the context of the solvable "toy model" of massive Klein-Gordon scalar field theory, with $m^2$ viewed as the "self-interaction parameter". Even in Minkowski spacetime, a serious difficulty arises from the fact that all integrals must be taken over a compact spacetime region to ensure convergence but any integration cutoff necessarily breaks Lorentz covariance. We show how covariant flow relations can be obtained by adding compensating "counterterms" in a manner similar to that of the Epstein-Glaser renormalization scheme. We also show how to eliminate dependence on the "infrared-cutoff scale" $L$, thereby yielding flow relations compatible with almost homogeneous scaling of the fields. In curved spacetime, the spacetime integration will cause the OPE coefficients to depend non-locally on the spacetime metric, in violation of the requirement that quantum fields should depend locally and covariantly on the metric. We show how this potentially serious difficulty can be overcome by replacing the metric with a suitable local polynomial approximation about the OPE expansion point. We thereby obtain local and covariant flow relations for the OPE coefficients of Klein-Gordon theory in curved Lorentzian spacetimes. In an appendix, we develop an algorithm for constructing local and covariant flow relations beyond our "toy model" based on the associativity properties of OPE coefficients, and we apply our method to $\lambda\phi^4$-theory. |
2004.10001 | Andrew Matas | Andrew Matas, Tim Dietrich, Alessandra Buonanno, Tanja Hinderer,
Michael P\"urrer, Francois Foucart, Michael Boyle, Matthew D. Duez, Lawrence
E. Kidder, Harald P. Pfeiffer, Mark A. Scheel | An aligned-spin neutron-star--black-hole waveform model based on the
effective-one-body approach and numerical-relativity simulations | 18 pages, 10 Figures | Phys. Rev. D 102, 043023 (2020) | 10.1103/PhysRevD.102.043023 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | After the discovery of gravitational waves from binary black holes (BBHs) and
binary neutron stars (BNSs) with the LIGO and Virgo detectors,
neutron-star--black-holes (NSBHs) are the natural next class of binary systems
to be observed. In this work, we develop a waveform model for aligned-spin
neutron-star--black-holes (NSBHs) combining a BBH baseline waveform (available
in the effective-one-body approach) with a phenomenological description of
tidal effects (extracted from numerical-relativity simulations), and correcting
the amplitude during the late inspiral, merger and ringdown to account for the
NS tidal disruption. We calibrate the amplitude corrections using NSBH
waveforms obtained with the SpEC and the SACRA codes. The model was calibrated
using simulations with NS masses in the range $1.2-1.4 M_\odot$, tidal
deformabilities up to $4200$ (for a 1.2 $M_\odot$ NS), and dimensionless BH
spin magnitude up to 0.9. Based on the simulations used, and on checking that
sensible waveforms are produced, we recommend our model to be employed with NS
mass in the range $1\mbox{--}3 M_\odot$, tidal deformability $0\mbox{--}5000$,
and BH spin magnitude up to $0.9$. We also validate our model against two new,
highly accurate NSBH waveforms with BH spin 0.9 and mass ratios 3 and 4,
characterized by tidal disruption, produced with SpEC, and find very good
agreement. We find that it will be challenging for the advanced
LIGO-Virgo--detector network at design sensitivity to distinguish different
source classes. We perform parameter-estimation on a synthetic
numerical-relativity signal in zero noise to study parameter biases. Finally,
we reanalyze GW170817, with the hypothesis that it is a NSBH. We do not find
evidence to distinguish the BNS and NSBH hypotheses, however the posterior for
the mass ratio is shifted to less equal masses under the NSBH hypothesis.
[Abstract abridged for arxiv].
| [
{
"created": "Tue, 21 Apr 2020 13:43:34 GMT",
"version": "v1"
},
{
"created": "Sun, 21 Feb 2021 18:12:12 GMT",
"version": "v2"
}
] | 2021-02-23 | [
[
"Matas",
"Andrew",
""
],
[
"Dietrich",
"Tim",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Hinderer",
"Tanja",
""
],
[
"Pürrer",
"Michael",
""
],
[
"Foucart",
"Francois",
""
],
[
"Boyle",
"Michael",
""
],
[
"Duez",
"Matthew D.",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"Pfeiffer",
"Harald P.",
""
],
[
"Scheel",
"Mark A.",
""
]
] | After the discovery of gravitational waves from binary black holes (BBHs) and binary neutron stars (BNSs) with the LIGO and Virgo detectors, neutron-star--black-holes (NSBHs) are the natural next class of binary systems to be observed. In this work, we develop a waveform model for aligned-spin neutron-star--black-holes (NSBHs) combining a BBH baseline waveform (available in the effective-one-body approach) with a phenomenological description of tidal effects (extracted from numerical-relativity simulations), and correcting the amplitude during the late inspiral, merger and ringdown to account for the NS tidal disruption. We calibrate the amplitude corrections using NSBH waveforms obtained with the SpEC and the SACRA codes. The model was calibrated using simulations with NS masses in the range $1.2-1.4 M_\odot$, tidal deformabilities up to $4200$ (for a 1.2 $M_\odot$ NS), and dimensionless BH spin magnitude up to 0.9. Based on the simulations used, and on checking that sensible waveforms are produced, we recommend our model to be employed with NS mass in the range $1\mbox{--}3 M_\odot$, tidal deformability $0\mbox{--}5000$, and BH spin magnitude up to $0.9$. We also validate our model against two new, highly accurate NSBH waveforms with BH spin 0.9 and mass ratios 3 and 4, characterized by tidal disruption, produced with SpEC, and find very good agreement. We find that it will be challenging for the advanced LIGO-Virgo--detector network at design sensitivity to distinguish different source classes. We perform parameter-estimation on a synthetic numerical-relativity signal in zero noise to study parameter biases. Finally, we reanalyze GW170817, with the hypothesis that it is a NSBH. We do not find evidence to distinguish the BNS and NSBH hypotheses, however the posterior for the mass ratio is shifted to less equal masses under the NSBH hypothesis. [Abstract abridged for arxiv]. |
0906.0668 | Hosein Haghi | Y. Sobouti, A. Hasani Zonoozi, H. Haghi | Tully-Fisher relation, key to dark matter companion of baryonic matter | 1 figure, 5 pages, submitted to A&A | Astron.Astrophys.507:635-638,2009 | 10.1051/0004-6361/200912571 | null | gr-qc astro-ph.GA | http://creativecommons.org/licenses/publicdomain/ | Rotation curves of spiral galaxies \emph{i}) fall off much less steeply than
the Keplerian curves do, and \emph{ii}) have asymptotic speeds almost
proportional to the fourth root of the mass of the galaxy, the Tully-Fisher
relation. These features alone are sufficient for assigning a dark companion to
the galaxy in an unambiguous way. In regions outside a spherical system, we
design a spherically symmetric spacetime to accommodate the peculiarities just
mentioned. Gravitation emerges in excess of what the observable matter can
produce. We attribute the excess gravitation to a hypothetical, dark, perfect
fluid companion to the galaxy and resort to the Tully-Fisher relation to deduce
its density and pressure. The dark density turns out to be proportional to the
square root of the mass of the galaxy and to fall off as $r^{-(2+\alpha)},
\alpha\ll 1$. The dark equation of state is barrotropic. For the interior of
the configuration, we require the continuity of the total force field at the
boundary of the system. This enables us to determine the size and the
distribution of the interior dark density and pressure in terms of the
structure of the observable matter. The formalism is nonlocal and nonlinear,
and the density and pressure of the dark matter at any spacetime point turn out
to depend on certain integrals of the baryonic matter over all or parts of the
system in a nonlinear manner.
| [
{
"created": "Wed, 3 Jun 2009 09:31:41 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Dec 2009 08:37:37 GMT",
"version": "v2"
}
] | 2010-11-02 | [
[
"Sobouti",
"Y.",
""
],
[
"Zonoozi",
"A. Hasani",
""
],
[
"Haghi",
"H.",
""
]
] | Rotation curves of spiral galaxies \emph{i}) fall off much less steeply than the Keplerian curves do, and \emph{ii}) have asymptotic speeds almost proportional to the fourth root of the mass of the galaxy, the Tully-Fisher relation. These features alone are sufficient for assigning a dark companion to the galaxy in an unambiguous way. In regions outside a spherical system, we design a spherically symmetric spacetime to accommodate the peculiarities just mentioned. Gravitation emerges in excess of what the observable matter can produce. We attribute the excess gravitation to a hypothetical, dark, perfect fluid companion to the galaxy and resort to the Tully-Fisher relation to deduce its density and pressure. The dark density turns out to be proportional to the square root of the mass of the galaxy and to fall off as $r^{-(2+\alpha)}, \alpha\ll 1$. The dark equation of state is barrotropic. For the interior of the configuration, we require the continuity of the total force field at the boundary of the system. This enables us to determine the size and the distribution of the interior dark density and pressure in terms of the structure of the observable matter. The formalism is nonlocal and nonlinear, and the density and pressure of the dark matter at any spacetime point turn out to depend on certain integrals of the baryonic matter over all or parts of the system in a nonlinear manner. |
gr-qc/9604034 | Fernando C. Lombardo | Mario Castagnino | The Mathematical Structure of Superspace as a Consequence of Time
Asymmetry | 45 pages, latex, no figures | Phys.Rev.D57:750-767,1998 | 10.1103/PhysRevD.57.750 | null | gr-qc | null | It is demonstrated how a convenient choice of the mathematical structure of
the quantum cosmology superspace, precisely the definition of a convenient
regular state superspace and the restriction of the dynamics to this space,
yields directly to an irreversible evolution, in the classical (and
semiclassical) phase of the universe, where:
Decoherence and correlations take place and therefore give origin to a
classical universe. The second law of thermodynamic is demonstrated. Connection
with Reichenbach branch system idea can be implemented. Some rough coincidence
with observational data are obtained. The arrows of time can be correlated.
Time asymmetry can be explained as a state space asymmetry (e. g. like a
spontaneous symmetry breaking All these facts solve the problem of
time-asymmetry and show that it is time asymmetry itself that defines the most
important features of mathematical structure of superspace.
| [
{
"created": "Wed, 17 Apr 1996 20:25:06 GMT",
"version": "v1"
}
] | 2010-11-19 | [
[
"Castagnino",
"Mario",
""
]
] | It is demonstrated how a convenient choice of the mathematical structure of the quantum cosmology superspace, precisely the definition of a convenient regular state superspace and the restriction of the dynamics to this space, yields directly to an irreversible evolution, in the classical (and semiclassical) phase of the universe, where: Decoherence and correlations take place and therefore give origin to a classical universe. The second law of thermodynamic is demonstrated. Connection with Reichenbach branch system idea can be implemented. Some rough coincidence with observational data are obtained. The arrows of time can be correlated. Time asymmetry can be explained as a state space asymmetry (e. g. like a spontaneous symmetry breaking All these facts solve the problem of time-asymmetry and show that it is time asymmetry itself that defines the most important features of mathematical structure of superspace. |
1810.06789 | Eric Ling | Eric Ling | The Big Bang is a Coordinate Singularity for $k = -1$ Inflationary FLRW
Spacetimes | 46 pages, 20 figures, v3 to appear in Foundations of Physics | null | 10.1007/s10701-020-00335-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the big bang is a coordinate singularity for a large class of $k
= -1$ inflationary FLRW spacetimes which we have dubbed 'Milne-like.' By
introducing a new set of coordinates, the big bang appears as a past boundary
of the universe where the metric is no longer degenerate -- a result which has
already been investigated in the context of vacuum decay [12]. We generalize
their results and approach the problem from a more mathematical perspective.
Similar to how investigating the geometrical properties of the $r = 2m$ event
horizon in Schwarzschild led to a better understanding of black holes, we
believe that investigating the geometrical properties of the big bang
coordinate singularity for Milne-like spacetimes could lead to a better
understanding of cosmology. We show how the mathematics of these spacetimes may
help illuminate certain issues associated with dark energy, dark matter, and
the universe's missing antimatter.
| [
{
"created": "Tue, 16 Oct 2018 01:59:36 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Jan 2019 18:43:33 GMT",
"version": "v2"
},
{
"created": "Thu, 20 Feb 2020 12:33:45 GMT",
"version": "v3"
}
] | 2020-03-12 | [
[
"Ling",
"Eric",
""
]
] | We show that the big bang is a coordinate singularity for a large class of $k = -1$ inflationary FLRW spacetimes which we have dubbed 'Milne-like.' By introducing a new set of coordinates, the big bang appears as a past boundary of the universe where the metric is no longer degenerate -- a result which has already been investigated in the context of vacuum decay [12]. We generalize their results and approach the problem from a more mathematical perspective. Similar to how investigating the geometrical properties of the $r = 2m$ event horizon in Schwarzschild led to a better understanding of black holes, we believe that investigating the geometrical properties of the big bang coordinate singularity for Milne-like spacetimes could lead to a better understanding of cosmology. We show how the mathematics of these spacetimes may help illuminate certain issues associated with dark energy, dark matter, and the universe's missing antimatter. |
1110.5480 | Yongge Ma | Li Qin and Yongge Ma | Coherent State Functional Integrals in Quantum Cosmology | 16 pages, errors corrected, published version in PRD | Phys. Rev. D 85 (2012), 063515 | 10.1103/PhysRevD.85.063515 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Coherent state functional integrals for the minisuperspace models of quantum
cosmology are studied. By the well-established canonical theories, the
transition amplitudes in the path-integral representations of Wheeler-DeWitt
quantum cosmology and loop quantum cosmology can be formulated through group
averaging. The effective action and Hamiltonian with higher-order quantum
corrections are thus obtained in both models. It turns out that for a
non-symmetric Hamiltonian constraint operator, the Moyal (star)-product emerges
naturally in the effective Hamiltonian. This reveals the intrinsic relation
among coherent state functional integral, effective theory and star-product.
Moreover, both the resulted effective theories imply a possible quantum
cosmological effect in large scale limit.
| [
{
"created": "Tue, 25 Oct 2011 12:18:54 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Mar 2012 13:46:41 GMT",
"version": "v2"
}
] | 2015-05-30 | [
[
"Qin",
"Li",
""
],
[
"Ma",
"Yongge",
""
]
] | Coherent state functional integrals for the minisuperspace models of quantum cosmology are studied. By the well-established canonical theories, the transition amplitudes in the path-integral representations of Wheeler-DeWitt quantum cosmology and loop quantum cosmology can be formulated through group averaging. The effective action and Hamiltonian with higher-order quantum corrections are thus obtained in both models. It turns out that for a non-symmetric Hamiltonian constraint operator, the Moyal (star)-product emerges naturally in the effective Hamiltonian. This reveals the intrinsic relation among coherent state functional integral, effective theory and star-product. Moreover, both the resulted effective theories imply a possible quantum cosmological effect in large scale limit. |
1806.09653 | Dmitriy Grad | D. A. Grad, S. A. Paston, A. A. Sheykin | Definitions of energy for the description of gravity as the splitting
theory | This version matches the published one | D. A. Grad et al 2018 J. Phys.: Conf. Ser. 1038 012007 | 10.1088/1742-6596/1038/1/012007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the definitions of energy, naturally arising in the splitting
theory, which is the field theoretic formulation of the Regge-Teitelboim
gravity. The latter regards our spacetime as a surface embedded in a flat bulk.
The splitting theory describes embedded spacetime in the language of the some
field theory in a flat bulk. We consider the Noether energy-momentum tensor
(EMT) and the metric EMT defined by the variation with respect to the metric of
a flat bulk. We discuss a localizability of energy. Then using these EMTs we
calculate the full energy of an isolated massive body. We compare the results
with the standard general relativity results obtained from the Einstein
energy-momentum pseudotensor (pEMT) and from the M{\o}ller pEMT. Finally, we
propose the several ways of correction of the definitions of the energy in the
splitting theory.
| [
{
"created": "Mon, 25 Jun 2018 18:28:04 GMT",
"version": "v1"
}
] | 2018-06-27 | [
[
"Grad",
"D. A.",
""
],
[
"Paston",
"S. A.",
""
],
[
"Sheykin",
"A. A.",
""
]
] | We study the definitions of energy, naturally arising in the splitting theory, which is the field theoretic formulation of the Regge-Teitelboim gravity. The latter regards our spacetime as a surface embedded in a flat bulk. The splitting theory describes embedded spacetime in the language of the some field theory in a flat bulk. We consider the Noether energy-momentum tensor (EMT) and the metric EMT defined by the variation with respect to the metric of a flat bulk. We discuss a localizability of energy. Then using these EMTs we calculate the full energy of an isolated massive body. We compare the results with the standard general relativity results obtained from the Einstein energy-momentum pseudotensor (pEMT) and from the M{\o}ller pEMT. Finally, we propose the several ways of correction of the definitions of the energy in the splitting theory. |
1903.09611 | Maksym Teslyk Mr | M.v. Teslyk, O.M. Teslyk, and L.V. Zadorozhna | Unruh effect and entropy of Schwarzschild black hole | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider Unruh effect as an origin for Schwarzschild black hole entropy
thus implying unitarian evolution of gravity. We simulate the black hole by set
of Unruh horizons and estimate total entropy of the system. Dependence on mass
and spin of the emitted particles is taken into account. The obtained results
may be easily extended to any other intrinsic degrees of freedom of the
particles. Unruh effect contribution to Schwarzschild black hole entropy is
presented in exact analytical form.
| [
{
"created": "Fri, 22 Mar 2019 17:11:16 GMT",
"version": "v1"
}
] | 2019-03-25 | [
[
"Teslyk",
"M. v.",
""
],
[
"Teslyk",
"O. M.",
""
],
[
"Zadorozhna",
"L. V.",
""
]
] | We consider Unruh effect as an origin for Schwarzschild black hole entropy thus implying unitarian evolution of gravity. We simulate the black hole by set of Unruh horizons and estimate total entropy of the system. Dependence on mass and spin of the emitted particles is taken into account. The obtained results may be easily extended to any other intrinsic degrees of freedom of the particles. Unruh effect contribution to Schwarzschild black hole entropy is presented in exact analytical form. |
gr-qc/0701018 | Felix Finster | Felix Finster, Niky Kamran, Joel Smoller, Shing-Tung Yau | A Rigorous Treatment of Energy Extraction from a Rotating Black Hole | 19 pages, LaTeX, proof of Propositions 2.3 and 3.1 given in more
detail | Commun.Math.Phys.287:829-847,2009 | 10.1007/s00220-009-0730-7 | null | gr-qc math-ph math.MP | null | The Cauchy problem is considered for the scalar wave equation in the Kerr
geometry. We prove that by choosing a suitable wave packet as initial data, one
can extract energy from the black hole, thereby putting supperradiance, the
wave analogue of the Penrose process, into a rigorous mathematical framework.
We quantify the maximal energy gain. We also compute the infinitesimal change
of mass and angular momentum of the black hole, in agreement with
Christodoulou's result for the Penrose process. The main mathematical tool is
our previously derived integral representation of the wave propagator.
| [
{
"created": "Mon, 1 Jan 2007 21:59:50 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Jul 2007 09:44:20 GMT",
"version": "v2"
},
{
"created": "Thu, 22 May 2008 09:44:15 GMT",
"version": "v3"
}
] | 2014-11-17 | [
[
"Finster",
"Felix",
""
],
[
"Kamran",
"Niky",
""
],
[
"Smoller",
"Joel",
""
],
[
"Yau",
"Shing-Tung",
""
]
] | The Cauchy problem is considered for the scalar wave equation in the Kerr geometry. We prove that by choosing a suitable wave packet as initial data, one can extract energy from the black hole, thereby putting supperradiance, the wave analogue of the Penrose process, into a rigorous mathematical framework. We quantify the maximal energy gain. We also compute the infinitesimal change of mass and angular momentum of the black hole, in agreement with Christodoulou's result for the Penrose process. The main mathematical tool is our previously derived integral representation of the wave propagator. |
1811.04490 | Travis Robson | Travis Robson, Neil J. Cornish | Detecting Gravitational Wave Bursts with LISA in the presence of
Instrumental Glitches | 15 pages, 9 figures | Phys. Rev. D 99, 024019 (2019) | 10.1103/PhysRevD.99.024019 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Laser Interferometer Space Antenna (LISA) will open a rich discovery
space in the milli-Hertz gravitational wave band. In addition to the
anticipated signals from many millions of binary systems, this band may contain
new and previously un-imagined sources for which we currently have no models.
To detect unmodeled and unexpected signals we need to be able to separate them
from instrumental noise artifacts, or glitches. Glitches are a regular feature
in the data from ground based laser interferometers, and they were also seen in
data from the LISA Pathfinder mission. In contrast to the situation on ground,
we will not have the luxury of having multiple independent detectors to help
separate unmodeled signals from glitches, and new techniques have to be
developed. Here we show that unmodeled gravitational wave bursts can be
detected with LISA by leveraging the different way in which instrument glitches
and gravitational wave bursts imprint themselves in the time-delay
interferometery data channels. We show that for signals with periods longer
than the light travel time between the spacecraft, the "breathing mode" or
Sagnac data combination is key to detection. Conversely, for short period
signals it is the time of arrival at each spacecraft that aids separation. We
investigate the conditions under which we can distinguish the origin of signals
and glitches consisting of a single sine-Gaussian wavelet and determine how
well we can characterize the signal. We find that gravitational waves bursts
can be unambiguously detected and characterized with just a single data channel
(four functioning laser links), though the signal separation and parameter
estimation improve significantly when all six laser links are operational.
| [
{
"created": "Sun, 11 Nov 2018 22:01:38 GMT",
"version": "v1"
}
] | 2019-01-16 | [
[
"Robson",
"Travis",
""
],
[
"Cornish",
"Neil J.",
""
]
] | The Laser Interferometer Space Antenna (LISA) will open a rich discovery space in the milli-Hertz gravitational wave band. In addition to the anticipated signals from many millions of binary systems, this band may contain new and previously un-imagined sources for which we currently have no models. To detect unmodeled and unexpected signals we need to be able to separate them from instrumental noise artifacts, or glitches. Glitches are a regular feature in the data from ground based laser interferometers, and they were also seen in data from the LISA Pathfinder mission. In contrast to the situation on ground, we will not have the luxury of having multiple independent detectors to help separate unmodeled signals from glitches, and new techniques have to be developed. Here we show that unmodeled gravitational wave bursts can be detected with LISA by leveraging the different way in which instrument glitches and gravitational wave bursts imprint themselves in the time-delay interferometery data channels. We show that for signals with periods longer than the light travel time between the spacecraft, the "breathing mode" or Sagnac data combination is key to detection. Conversely, for short period signals it is the time of arrival at each spacecraft that aids separation. We investigate the conditions under which we can distinguish the origin of signals and glitches consisting of a single sine-Gaussian wavelet and determine how well we can characterize the signal. We find that gravitational waves bursts can be unambiguously detected and characterized with just a single data channel (four functioning laser links), though the signal separation and parameter estimation improve significantly when all six laser links are operational. |
1012.0645 | Jiliang Jing | Mengjie Wang, Songbai Chen, Jiliang Jing | Second-order phase transition of Kehagias-Sfetsos black hole in deformed
H\v{o}rava-Lifshitz gravity | 9 pages, no figure, accepted for publication in PLB | Phys.Lett.B695:401-404,2011 | 10.1016/j.physletb.2010.11.055 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the second-order phase transition (SOPT) for the spherically
symmetric Kehagias-Sfetsos (KS) black hole in the deformed H\v{o}rava-Lifshitz
gravity by applying the methods of equilibrium and non-equilibrium
fluctuations. We find that, although the KS black hole has only one mass
parameter as the usual Schwarzschild ones, the SOPT will take place if the mass
of the KS black hole changes across the critical point
$\frac{\sqrt{5+\sqrt{33}}(\sqrt{33}-1)} {16\sqrt{\omega}} $. The result show us
that there is difference between the H\v{o}rava-Lifshitz gravity and the
Einstein's gravity theory.
| [
{
"created": "Fri, 3 Dec 2010 06:38:54 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Dec 2010 10:15:20 GMT",
"version": "v2"
}
] | 2011-10-19 | [
[
"Wang",
"Mengjie",
""
],
[
"Chen",
"Songbai",
""
],
[
"Jing",
"Jiliang",
""
]
] | We study the second-order phase transition (SOPT) for the spherically symmetric Kehagias-Sfetsos (KS) black hole in the deformed H\v{o}rava-Lifshitz gravity by applying the methods of equilibrium and non-equilibrium fluctuations. We find that, although the KS black hole has only one mass parameter as the usual Schwarzschild ones, the SOPT will take place if the mass of the KS black hole changes across the critical point $\frac{\sqrt{5+\sqrt{33}}(\sqrt{33}-1)} {16\sqrt{\omega}} $. The result show us that there is difference between the H\v{o}rava-Lifshitz gravity and the Einstein's gravity theory. |
gr-qc/9210013 | Patrick Brady | Warren G. Anderson, Patrick R. Brady, Werner Israel, and Sharon M.
Morsink | Quantum Effects in Black Hole Interiors | 13 pages, 1 figure (not included), RevTex | Phys.Rev.Lett. 70 (1993) 1041-1044 | 10.1103/PhysRevLett.70.1041 | Alberta-Thy-36-92 | gr-qc | null | The Weyl curvature inside a black hole formed in a generic collapse grows,
classically without bound, near to the inner horizon, due to partial absorption
and blueshifting of the radiative tail of the collapse. Using a spherical
model, we examine how this growth is modified by quantum effects of conformally
coupled massless fields.
| [
{
"created": "Fri, 23 Oct 1992 17:27:15 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Anderson",
"Warren G.",
""
],
[
"Brady",
"Patrick R.",
""
],
[
"Israel",
"Werner",
""
],
[
"Morsink",
"Sharon M.",
""
]
] | The Weyl curvature inside a black hole formed in a generic collapse grows, classically without bound, near to the inner horizon, due to partial absorption and blueshifting of the radiative tail of the collapse. Using a spherical model, we examine how this growth is modified by quantum effects of conformally coupled massless fields. |
2309.10934 | Peter Martin | Michael Bishop, Peter Martin, Douglas Singleton | Quantum gravity, the cosmological constant, and parity transformation | 10 pages, revtex-4, 0 figures, published in PLB | Phys.Lett.B 845 (2023) 138173 | 10.1016/j.physletb.2023.138173 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | One of the leading issues in quantum field theory and cosmology is the
mismatch between the observed and calculated values for the cosmological
constant in Einstein's field equations of up to 120 orders of magnitude. In
this paper, we discuss new methods to potentially bridge this chasm using the
generalized uncertainty principle (GUP). We find that if quantum gravity GUP
models are the solution to this puzzle, then it may require the gravitationally
modified position operator undergo a parity transformation at high energies.
| [
{
"created": "Tue, 19 Sep 2023 21:11:27 GMT",
"version": "v1"
}
] | 2023-09-21 | [
[
"Bishop",
"Michael",
""
],
[
"Martin",
"Peter",
""
],
[
"Singleton",
"Douglas",
""
]
] | One of the leading issues in quantum field theory and cosmology is the mismatch between the observed and calculated values for the cosmological constant in Einstein's field equations of up to 120 orders of magnitude. In this paper, we discuss new methods to potentially bridge this chasm using the generalized uncertainty principle (GUP). We find that if quantum gravity GUP models are the solution to this puzzle, then it may require the gravitationally modified position operator undergo a parity transformation at high energies. |
1709.02259 | Muhammad Sharif | M. Sharif and Arfa Waseem | On the Stability of Einstein Universe in f(R,T,R_{\mu\nu}T^{\mu\nu})
Gravity | 18 pages, 4 figures | Mod. Phys. Lett. A 33(2018)1850216 | 10.1142/S0217732318502164 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper investigates the existence and stability of Einstein universe in
the context of $f(R,T,Q)$ gravity, where $Q=R_{\mu\nu}T^{\mu\nu}$. Considering
linear homogeneous perturbations around scale factor and energy density, we
formulate static as well as perturbed field equations. We parameterize the
stability regions corresponding to conserved as well as non-conserved
energy-momentum tensor using linear equation of state parameter for particular
models of this gravity. The graphical analysis concludes that for a suitable
choice of parameters, the stable regions of the Einstein universe are obtained.
| [
{
"created": "Wed, 6 Sep 2017 05:30:06 GMT",
"version": "v1"
}
] | 2018-12-19 | [
[
"Sharif",
"M.",
""
],
[
"Waseem",
"Arfa",
""
]
] | This paper investigates the existence and stability of Einstein universe in the context of $f(R,T,Q)$ gravity, where $Q=R_{\mu\nu}T^{\mu\nu}$. Considering linear homogeneous perturbations around scale factor and energy density, we formulate static as well as perturbed field equations. We parameterize the stability regions corresponding to conserved as well as non-conserved energy-momentum tensor using linear equation of state parameter for particular models of this gravity. The graphical analysis concludes that for a suitable choice of parameters, the stable regions of the Einstein universe are obtained. |
2004.14206 | Milad Hajebrahimi | Milad Hajebrahimi and Kourosh Nozari | A quantum-corrected approach to black hole radiation via a tunneling
process | 14 pages, 3 figures | Progress of Theoretical and Experimental Physics, 2020(4), 043E03 | 10.1093/ptep/ptaa032 | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the language of black hole physics, Hawking radiation is one of the most
controversial subjects about which there exist lots of puzzles, including the
information loss problem and the question of whether this radiation is thermal
or not. In this situation, a possible way to face these problems is to bring
quantum effects into play, also taking into account self-gravitational effects
in the scenario. We consider a quantum-corrected form of the Schwarzschild
black hole inspired by the pioneering work of Kazakov and Solodukhin to modify
the famous Parikh-Wilczek tunneling process for Hawking radiation. We prove
that in this framework the radiation is not thermal, with a correlation
function more effective than the Parikh-Wilczek result, and the information
loss problem can be addressed more successfully. Also, we realize that quantum
correction affects things in the same way as an electric charge. So, it seems
that quantum correction in this framework has something to do with the electric
charge.
| [
{
"created": "Tue, 28 Apr 2020 13:06:41 GMT",
"version": "v1"
}
] | 2020-04-30 | [
[
"Hajebrahimi",
"Milad",
""
],
[
"Nozari",
"Kourosh",
""
]
] | In the language of black hole physics, Hawking radiation is one of the most controversial subjects about which there exist lots of puzzles, including the information loss problem and the question of whether this radiation is thermal or not. In this situation, a possible way to face these problems is to bring quantum effects into play, also taking into account self-gravitational effects in the scenario. We consider a quantum-corrected form of the Schwarzschild black hole inspired by the pioneering work of Kazakov and Solodukhin to modify the famous Parikh-Wilczek tunneling process for Hawking radiation. We prove that in this framework the radiation is not thermal, with a correlation function more effective than the Parikh-Wilczek result, and the information loss problem can be addressed more successfully. Also, we realize that quantum correction affects things in the same way as an electric charge. So, it seems that quantum correction in this framework has something to do with the electric charge. |
1711.10502 | Vitor Cardoso | Vitor Cardoso, Joao L. Costa, Kyriakos Destounis, Peter Hintz, Aron
Jansen | Quasinormal modes and Strong Cosmic Censorship | To appear in Physical Review Letters, as an Editors' Suggestion | Phys. Rev. Lett. 120, 031103 (2018) | 10.1103/PhysRevLett.120.031103 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The fate of Cauchy horizons, such as those found inside charged black holes,
is intrinsically connected to the decay of small perturbations exterior to the
event horizon. As such, the validity of the strong cosmic censorship (SCC)
conjecture is tied to how effectively the exterior damps fluctuations. Here, we
study massless scalar fields in the exterior of Reissner--Nordstrom--de Sitter
black holes. Their decay rates are governed by quasinormal modes of the black
hole. We identify three families of modes in these spacetimes: one directly
linked to the photon sphere, well described by standard WKB-type tools; another
family whose existence and timescale is closely related to the de Sitter
horizon. Finally, a third family which dominates for near-extremally-charged
black holes and which is also present in asymptotically flat spacetimes. The
last two families of modes seem to have gone unnoticed in the literature. We
give a detailed description of linear scalar perturbations of such black holes,
and conjecture that SCC is violated in the near extremal regime.
| [
{
"created": "Tue, 28 Nov 2017 19:00:06 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Jan 2018 21:06:57 GMT",
"version": "v2"
}
] | 2018-01-24 | [
[
"Cardoso",
"Vitor",
""
],
[
"Costa",
"Joao L.",
""
],
[
"Destounis",
"Kyriakos",
""
],
[
"Hintz",
"Peter",
""
],
[
"Jansen",
"Aron",
""
]
] | The fate of Cauchy horizons, such as those found inside charged black holes, is intrinsically connected to the decay of small perturbations exterior to the event horizon. As such, the validity of the strong cosmic censorship (SCC) conjecture is tied to how effectively the exterior damps fluctuations. Here, we study massless scalar fields in the exterior of Reissner--Nordstrom--de Sitter black holes. Their decay rates are governed by quasinormal modes of the black hole. We identify three families of modes in these spacetimes: one directly linked to the photon sphere, well described by standard WKB-type tools; another family whose existence and timescale is closely related to the de Sitter horizon. Finally, a third family which dominates for near-extremally-charged black holes and which is also present in asymptotically flat spacetimes. The last two families of modes seem to have gone unnoticed in the literature. We give a detailed description of linear scalar perturbations of such black holes, and conjecture that SCC is violated in the near extremal regime. |
1306.2367 | Stefano Bertone | Stefano Bertone, Olivier Minazzoli, Mariateresa Crosta, Christophe Le
Poncin-Lafitte, Alberto Vecchiato, Marie-Christine Angonin | Time Transfer functions as a way to validate light propagation solutions
for space astrometry | 16 pages, submitted to CQG | null | 10.1088/0264-9381/31/1/015021 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Given the extreme accuracy of modern space astrometry, a precise relativistic
modeling of observations is required. Concerning light propagation, the
standard procedure is the solution of the null-geodesic equations. However,
another approach based on the Time Transfer Functions (TTF) has demonstrated
its capability to give access to key quantities such as the time of flight of a
light signal between two point-events and the tangent vector to its
null-geodesic in a weak gravitational field using an integral-based method. The
availability of several models, formulated in different and independent ways,
must not be considered like an oversized relativistic toolbox. Quite the
contrary, they are needed as validation to put future experimental results on
solid ground. The objective of this work is then twofold. First, we build the
time of flight and tangent vectors in a closed form within the TTF formalism
giving the case of a time dependent metric. Second, we show how to use this new
approach to obtain a comparison of the TTF with two existing modelings, namely
GREM and RAMOD. In this way, we evidentiate the mutual consistency of the three
models, opening the basis for further links between all the approaches, which
is mandatory for the interpretation of future space missions data. This will be
illustrated through two recognized cases: a static gravitational field and a
system of monopoles in uniform motion.
| [
{
"created": "Mon, 10 Jun 2013 22:17:06 GMT",
"version": "v1"
}
] | 2013-11-26 | [
[
"Bertone",
"Stefano",
""
],
[
"Minazzoli",
"Olivier",
""
],
[
"Crosta",
"Mariateresa",
""
],
[
"Poncin-Lafitte",
"Christophe Le",
""
],
[
"Vecchiato",
"Alberto",
""
],
[
"Angonin",
"Marie-Christine",
""
]
] | Given the extreme accuracy of modern space astrometry, a precise relativistic modeling of observations is required. Concerning light propagation, the standard procedure is the solution of the null-geodesic equations. However, another approach based on the Time Transfer Functions (TTF) has demonstrated its capability to give access to key quantities such as the time of flight of a light signal between two point-events and the tangent vector to its null-geodesic in a weak gravitational field using an integral-based method. The availability of several models, formulated in different and independent ways, must not be considered like an oversized relativistic toolbox. Quite the contrary, they are needed as validation to put future experimental results on solid ground. The objective of this work is then twofold. First, we build the time of flight and tangent vectors in a closed form within the TTF formalism giving the case of a time dependent metric. Second, we show how to use this new approach to obtain a comparison of the TTF with two existing modelings, namely GREM and RAMOD. In this way, we evidentiate the mutual consistency of the three models, opening the basis for further links between all the approaches, which is mandatory for the interpretation of future space missions data. This will be illustrated through two recognized cases: a static gravitational field and a system of monopoles in uniform motion. |
1009.5231 | G. Dautcourt | G. Dautcourt | The lightcone of G\"odel-like spacetimes | 19 pages, 1 figure | Class.Quant.Grav.27:225024,2010 | 10.1088/0264-9381/27/22/225024 | AEI-2010-151 | gr-qc | http://creativecommons.org/licenses/by-nc-sa/3.0/ | A study of the lightcone of the G\"odel universe is extended to the so-called
G\"odel-like spacetimes. This family of highly symmetric 4-D Lorentzian spaces
is defined by metrics of the form $ds^2=-(dt+H(x)dy)^2+D^2(x)dy^2+dx^2+dz^2$,
together with the requirement of spacetime homogeneity, and includes the
G\"odel metric. The quasi-periodic refocussing of cone generators with
startling lens properties, discovered by Ozsv\'{a}th and Sch\"ucking for the
lightcone of a plane gravitational wave and also found in the G\"odel universe,
is a feature of the whole G\"odel family. We discuss geometrical properties of
caustics and show that (a) the focal surfaces are two-dimensional null surfaces
generated by non-geodesic null curves and (b) intrinsic differential invariants
of the cone attain finite values at caustic subsets.
| [
{
"created": "Mon, 27 Sep 2010 11:49:43 GMT",
"version": "v1"
}
] | 2011-03-28 | [
[
"Dautcourt",
"G.",
""
]
] | A study of the lightcone of the G\"odel universe is extended to the so-called G\"odel-like spacetimes. This family of highly symmetric 4-D Lorentzian spaces is defined by metrics of the form $ds^2=-(dt+H(x)dy)^2+D^2(x)dy^2+dx^2+dz^2$, together with the requirement of spacetime homogeneity, and includes the G\"odel metric. The quasi-periodic refocussing of cone generators with startling lens properties, discovered by Ozsv\'{a}th and Sch\"ucking for the lightcone of a plane gravitational wave and also found in the G\"odel universe, is a feature of the whole G\"odel family. We discuss geometrical properties of caustics and show that (a) the focal surfaces are two-dimensional null surfaces generated by non-geodesic null curves and (b) intrinsic differential invariants of the cone attain finite values at caustic subsets. |
1711.09270 | Vasilis Oikonomou | K. Kleidis, V.K. Oikonomou | Loop Quantum Cosmology Corrected Gauss-Bonnet Singular Cosmology | IJGMMP Accepted | null | 10.1142/S0219887818500640 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we investigate which Loop Quantum Cosmology corrected
Gauss-Bonnet $F(\mathcal{G})$ gravity can realize two singular cosmological
scenarios, the intermediate inflation and the singular bounce scenarios. The
intermediate inflation scenario has a Type III sudden singularity at $t=0$,
while the singular bounce has a soft Type IV singularity. By using perturbative
techniques, we find the holonomy corrected $F(\mathcal{G})$ gravities that
generate at leading order the aforementioned cosmologies and we also argue that
the effect of the holonomy corrections is minor to the power spectrum of the
primordial curvature perturbations of the classical theory.
| [
{
"created": "Sat, 25 Nov 2017 18:18:16 GMT",
"version": "v1"
}
] | 2018-03-28 | [
[
"Kleidis",
"K.",
""
],
[
"Oikonomou",
"V. K.",
""
]
] | In this work we investigate which Loop Quantum Cosmology corrected Gauss-Bonnet $F(\mathcal{G})$ gravity can realize two singular cosmological scenarios, the intermediate inflation and the singular bounce scenarios. The intermediate inflation scenario has a Type III sudden singularity at $t=0$, while the singular bounce has a soft Type IV singularity. By using perturbative techniques, we find the holonomy corrected $F(\mathcal{G})$ gravities that generate at leading order the aforementioned cosmologies and we also argue that the effect of the holonomy corrections is minor to the power spectrum of the primordial curvature perturbations of the classical theory. |
2302.13634 | Marius Adrian Oancea | Lars Andersson, Marius A. Oancea | Spin Hall effects in the sky | null | Class. Quantum Grav. 40 154002 (2023) | 10.1088/1361-6382/ace021 | null | gr-qc physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In many areas of physics, the propagation of wave packets carrying intrinsic
angular momentum is generally influenced by spin-orbit interactions. This is
the main mechanism behind spin Hall effects, which result in wave packets
following spin-dependent trajectories. Spin Hall effects have been observed in
several experiments for electrons in condensed matter systems and for light
propagating in inhomogeneous optical media. Similar effects have also been
predicted for wave packets propagating in inhomogeneous gravitational fields.
We give a brief introduction to gravitational spin Hall effects, emphasizing
the analogies with the spin Hall effect of light in optics. Furthermore, we
review the most promising astrophysical avenues that could lead to experimental
observations of the gravitational spin Hall effect.
| [
{
"created": "Mon, 27 Feb 2023 09:59:07 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Jul 2023 13:08:11 GMT",
"version": "v2"
}
] | 2023-07-11 | [
[
"Andersson",
"Lars",
""
],
[
"Oancea",
"Marius A.",
""
]
] | In many areas of physics, the propagation of wave packets carrying intrinsic angular momentum is generally influenced by spin-orbit interactions. This is the main mechanism behind spin Hall effects, which result in wave packets following spin-dependent trajectories. Spin Hall effects have been observed in several experiments for electrons in condensed matter systems and for light propagating in inhomogeneous optical media. Similar effects have also been predicted for wave packets propagating in inhomogeneous gravitational fields. We give a brief introduction to gravitational spin Hall effects, emphasizing the analogies with the spin Hall effect of light in optics. Furthermore, we review the most promising astrophysical avenues that could lead to experimental observations of the gravitational spin Hall effect. |
2405.09124 | Kirill Bronnikov | S.V. Bolokhov, K.A. Bronnikov, M.V. Skvortsova | A regular center instead of a black bounce | 16 pages, 6 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The widely discussed ``black-bounce'' mechanism of removing a singularity at
$r=0$ in a spherically symmetric space-time, proposed by Simpson and Visser,
consists in removing the point $r=0$ and its close neighborhood, resulting in
emergence of a regular minimum of the spherical radius that can be a wormhole
throat or a regular bounce. Instead, it has been recently proposed to make
$r=0$ a regular center by properly modifying the metric, still preserving its
form in regions far from $r=0$. Different algorithms of such modifications have
been formulated for a few classes of singularities. The previous paper
considered space-times whose Ricci tensor satisfies the condition $R^t_t
=R^r_r$, and regular modifications were obtained for the Schwarzschild,
Reissner-Nordstr\"om metrics, and two examples of solutions with magnetic
fields obeying nonlinear electrodynamics (NED). The present paper considers
regular modifications of more general space-times, and as examples,
modifications with a regular center have been obtained for the Fisher (also
known as JNW) solution with a naked singularity and a family of dilatonic black
holes. Possible field sources of the new regular metrics are considered in the
framework of general relativity (GR), using the fact that any static,
spherically symmetric metric with a combined source involving NED and a scalar
field with some self-interaction potential. This scalar field is, in general,
not required to be of phantom nature (unlike the sources for black bounces),
but in the examples discussed here, the possible scalar sources are phantom in
a close neighborhood of $r=0$ and are canonical outside it.
| [
{
"created": "Wed, 15 May 2024 06:40:32 GMT",
"version": "v1"
}
] | 2024-05-16 | [
[
"Bolokhov",
"S. V.",
""
],
[
"Bronnikov",
"K. A.",
""
],
[
"Skvortsova",
"M. V.",
""
]
] | The widely discussed ``black-bounce'' mechanism of removing a singularity at $r=0$ in a spherically symmetric space-time, proposed by Simpson and Visser, consists in removing the point $r=0$ and its close neighborhood, resulting in emergence of a regular minimum of the spherical radius that can be a wormhole throat or a regular bounce. Instead, it has been recently proposed to make $r=0$ a regular center by properly modifying the metric, still preserving its form in regions far from $r=0$. Different algorithms of such modifications have been formulated for a few classes of singularities. The previous paper considered space-times whose Ricci tensor satisfies the condition $R^t_t =R^r_r$, and regular modifications were obtained for the Schwarzschild, Reissner-Nordstr\"om metrics, and two examples of solutions with magnetic fields obeying nonlinear electrodynamics (NED). The present paper considers regular modifications of more general space-times, and as examples, modifications with a regular center have been obtained for the Fisher (also known as JNW) solution with a naked singularity and a family of dilatonic black holes. Possible field sources of the new regular metrics are considered in the framework of general relativity (GR), using the fact that any static, spherically symmetric metric with a combined source involving NED and a scalar field with some self-interaction potential. This scalar field is, in general, not required to be of phantom nature (unlike the sources for black bounces), but in the examples discussed here, the possible scalar sources are phantom in a close neighborhood of $r=0$ and are canonical outside it. |
2008.12143 | Sergey Chervon | Sergey V. Chervon, J\'ulio C. Fabris and Igor V. Fomin | Black holes and wormholes in $f(R)$ gravity with a kinetic curvature
scalar | 25 pages. arXiv admin note: text overlap with arXiv:2005.11858 | Class.Quant.Grav. 38 (2021) 11, 115005 | 10.1088/1361-6382/abebf0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the chiral self-gravitating model (CSGM) of a special type in the
spherically symmetric static spacetime in Einstein frame. Such CSGM is derived,
by virtue of Weyl conformal transformation, from a gravity model in the Jordan
frame corresponding to a modified $f(R)$ gravity with a kinetic scalar
curvature. We investigate the model using harmonic coordinates and consider a
special case of the scaling transformation from the Jordan frame. We find
classes of solutions corresponding to a zero potential and we investigate
horizons, centers and the asymptotic behavior of the obtained solutions. Other
classes of solutions (for the potential not equal to zero) are found using a
special relation (ansatz) between the metric components. Investigations of
horizons, centers and asymptotic behavior of obtained solutions for this new
case are performed as well. Comparative analysis with the solutions obtained
earlier in literature is made.
| [
{
"created": "Tue, 25 Aug 2020 18:40:22 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Mar 2022 14:16:50 GMT",
"version": "v2"
}
] | 2022-03-02 | [
[
"Chervon",
"Sergey V.",
""
],
[
"Fabris",
"Júlio C.",
""
],
[
"Fomin",
"Igor V.",
""
]
] | We study the chiral self-gravitating model (CSGM) of a special type in the spherically symmetric static spacetime in Einstein frame. Such CSGM is derived, by virtue of Weyl conformal transformation, from a gravity model in the Jordan frame corresponding to a modified $f(R)$ gravity with a kinetic scalar curvature. We investigate the model using harmonic coordinates and consider a special case of the scaling transformation from the Jordan frame. We find classes of solutions corresponding to a zero potential and we investigate horizons, centers and the asymptotic behavior of the obtained solutions. Other classes of solutions (for the potential not equal to zero) are found using a special relation (ansatz) between the metric components. Investigations of horizons, centers and asymptotic behavior of obtained solutions for this new case are performed as well. Comparative analysis with the solutions obtained earlier in literature is made. |
1212.5806 | Francisco Lobo | Francisco S. N. Lobo, Foad Parsaei, Nematollah Riazi | New asymptotically flat phantom wormhole solutions | 7 pages, 2 figures. V2: 11 pages, 6 figures; two new solutions,
stability discussion and references added; to appear in PRD. V3: typos
corrected | Phys.Rev.D87:084030,2013 | 10.1103/PhysRevD.87.084030 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A possible cause of the late-time cosmic acceleration is an exotic fluid with
an equation of state lying within the phantom regime, i.e., $w=p/\rho <-1$. The
latter violates the null energy condition, which is a fundamental ingredient in
wormhole physics. Thus, cosmic phantom energy may, in principle, provide a
natural fluid to support wormholes. In this work, we find new asymptotically
flat wormhole solutions supported by the phantom energy equation of state,
consequently extending previous solutions. Thus, there is no need to surgically
paste the interior wormhole geometry to an exterior vacuum spacetime. In the
first example, we carefully construct a specific shape function, where the
energy density and pressures vanish at large distances as $\sim 1/r^{n}$, with
$n>0$. We also consider the "volume integral quantifier", which provides useful
information regarding the total amount of energy condition violating matter,
and show that, in principle, it is possible to construct asymptotically flat
wormhole solutions with an arbitrary small amount of energy condition violating
matter. In the second example, we analyse two equations of state, i.e.,
$p_r=p_r(\rho)$ and $p_t=p_t(\rho)$, where we consider a specific integrability
condition in order to obtain exact asymptotically flat wormhole solutions. In
the final example, we postulate a smooth energy density profile, possessing a
maximum at the throat and vanishing at spatial infinity.
| [
{
"created": "Sun, 23 Dec 2012 15:26:34 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Mar 2013 23:05:30 GMT",
"version": "v2"
},
{
"created": "Wed, 10 Apr 2013 08:14:12 GMT",
"version": "v3"
}
] | 2013-04-12 | [
[
"Lobo",
"Francisco S. N.",
""
],
[
"Parsaei",
"Foad",
""
],
[
"Riazi",
"Nematollah",
""
]
] | A possible cause of the late-time cosmic acceleration is an exotic fluid with an equation of state lying within the phantom regime, i.e., $w=p/\rho <-1$. The latter violates the null energy condition, which is a fundamental ingredient in wormhole physics. Thus, cosmic phantom energy may, in principle, provide a natural fluid to support wormholes. In this work, we find new asymptotically flat wormhole solutions supported by the phantom energy equation of state, consequently extending previous solutions. Thus, there is no need to surgically paste the interior wormhole geometry to an exterior vacuum spacetime. In the first example, we carefully construct a specific shape function, where the energy density and pressures vanish at large distances as $\sim 1/r^{n}$, with $n>0$. We also consider the "volume integral quantifier", which provides useful information regarding the total amount of energy condition violating matter, and show that, in principle, it is possible to construct asymptotically flat wormhole solutions with an arbitrary small amount of energy condition violating matter. In the second example, we analyse two equations of state, i.e., $p_r=p_r(\rho)$ and $p_t=p_t(\rho)$, where we consider a specific integrability condition in order to obtain exact asymptotically flat wormhole solutions. In the final example, we postulate a smooth energy density profile, possessing a maximum at the throat and vanishing at spatial infinity. |
2403.06886 | Shaobing Yuan | Shaobing Yuan, Changkai Luo, Zezhou Hu, Zhenyu Zhang, Bin Chen | QED Effects on Kerr-Newman Black Hole Shadows | 14 pages, 8 figures; v2: references added and minor revisions | null | null | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | Incorporating first-order QED effects, we explore the shadows of Kerr-Newman
black holes with a magnetic charge through the numerical backward ray-tracing
method. Our investigation accounts for both the direct influence of the
electromagnetic field on light rays and the distortion of the background
spacetime metric due to QED corrections. We notice that the area of the shadow
increases with the QED effect, mainly due to the fact that the photons move
more slowly in the effective medium and become easier to be trapped by the
black hole.
| [
{
"created": "Mon, 11 Mar 2024 16:43:09 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Mar 2024 14:58:39 GMT",
"version": "v2"
}
] | 2024-03-27 | [
[
"Yuan",
"Shaobing",
""
],
[
"Luo",
"Changkai",
""
],
[
"Hu",
"Zezhou",
""
],
[
"Zhang",
"Zhenyu",
""
],
[
"Chen",
"Bin",
""
]
] | Incorporating first-order QED effects, we explore the shadows of Kerr-Newman black holes with a magnetic charge through the numerical backward ray-tracing method. Our investigation accounts for both the direct influence of the electromagnetic field on light rays and the distortion of the background spacetime metric due to QED corrections. We notice that the area of the shadow increases with the QED effect, mainly due to the fact that the photons move more slowly in the effective medium and become easier to be trapped by the black hole. |
2104.09019 | Naoki Sato | Naoki Sato | The Effect of Spacetime Curvature on Statistical Distributions | 23 pages, 5 figures | Class. Quantum Grav. 38 165003 (2021) | 10.1088/1361-6382/ac11a9 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Boltzmann distribution of an ideal gas is determined by the Hamiltonian
function generating single particle dynamics. Systems with higher complexity
often exhibit topological constraints, which are independent of the Hamiltonian
and may affect the shape of the distribution function as well. Here, we study a
further source of heterogeneity, the curvature of spacetime arising from the
general theory of relativity. The present construction relies on three
assumptions: first, the statistical ensemble is made of particles obeying
geodesic equations, which define the phase space of the system. Next, the
metric coefficients are time-symmetric, implying that, if thermodynamic
equilibrium is achieved, all physical observables are independent of coordinate
time. Finally, ergodicity is enforced with respect to proper time, so that
ambiguity in the choice of a time variable for the statistical ensemble is
removed. Under these hypothesis, we derive the distribution function of
thermodynamic equilibrium, and verify that it reduces to the Boltzmann
distribution in the classical limit. We further show that spacetime curvature
affects physical observables, even far from the source of the metric. Two
examples are analyzed: an ideal gas in Schwarzschild spacetime and a charged
gas in Kerr-Newman spacetime. In the Schwarzschild case, conservation of
macroscopic constraints, such as angular momentum, combined with relativistic
distortion of the distribution function can produce configurations with
decreasing density and growing azimuthal rotation velocity far from the event
horizon of the central mass. In the Kerr-Newman case, it is found that kinetic
energy associated with azimuthal rotations is an increasing function of the
radial coordinate, and it eventually approaches a constant value corresponding
to classical equipartition, even though spatial particle density decreases.
| [
{
"created": "Mon, 19 Apr 2021 02:30:13 GMT",
"version": "v1"
}
] | 2021-07-29 | [
[
"Sato",
"Naoki",
""
]
] | The Boltzmann distribution of an ideal gas is determined by the Hamiltonian function generating single particle dynamics. Systems with higher complexity often exhibit topological constraints, which are independent of the Hamiltonian and may affect the shape of the distribution function as well. Here, we study a further source of heterogeneity, the curvature of spacetime arising from the general theory of relativity. The present construction relies on three assumptions: first, the statistical ensemble is made of particles obeying geodesic equations, which define the phase space of the system. Next, the metric coefficients are time-symmetric, implying that, if thermodynamic equilibrium is achieved, all physical observables are independent of coordinate time. Finally, ergodicity is enforced with respect to proper time, so that ambiguity in the choice of a time variable for the statistical ensemble is removed. Under these hypothesis, we derive the distribution function of thermodynamic equilibrium, and verify that it reduces to the Boltzmann distribution in the classical limit. We further show that spacetime curvature affects physical observables, even far from the source of the metric. Two examples are analyzed: an ideal gas in Schwarzschild spacetime and a charged gas in Kerr-Newman spacetime. In the Schwarzschild case, conservation of macroscopic constraints, such as angular momentum, combined with relativistic distortion of the distribution function can produce configurations with decreasing density and growing azimuthal rotation velocity far from the event horizon of the central mass. In the Kerr-Newman case, it is found that kinetic energy associated with azimuthal rotations is an increasing function of the radial coordinate, and it eventually approaches a constant value corresponding to classical equipartition, even though spatial particle density decreases. |
2305.02004 | Jonatan Herrera | Sa\'ul Burgos, Jos\'e Luis Flores, J\'onatan Herrera | The c-completion of Lorentzian metric spaces | 29 pages, 2 figures | null | null | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Inspired by some Lorentzian versions of the notion of metric and length space
introduced by Kunzinger and S\"amman, and more recently, by M\"uller, and
Minguzzi and S\"uhr, we revisit the notion of Lorentzian metric space in order
to later construct the c-completion of these general objects. We not only prove
that this construction is feasible in great generality for these objects,
including spacetimes of low regularity, but also endow the c-completion with a
structure of Lorentzian metric space by itself. We also prove that the
c-completion constitutes a well-suited extension of the original space, which
really completes it in a precise sense and becomes sensible to certain causal
properties of that space.
| [
{
"created": "Wed, 3 May 2023 09:51:56 GMT",
"version": "v1"
},
{
"created": "Tue, 16 May 2023 16:25:03 GMT",
"version": "v2"
}
] | 2023-05-17 | [
[
"Burgos",
"Saúl",
""
],
[
"Flores",
"José Luis",
""
],
[
"Herrera",
"Jónatan",
""
]
] | Inspired by some Lorentzian versions of the notion of metric and length space introduced by Kunzinger and S\"amman, and more recently, by M\"uller, and Minguzzi and S\"uhr, we revisit the notion of Lorentzian metric space in order to later construct the c-completion of these general objects. We not only prove that this construction is feasible in great generality for these objects, including spacetimes of low regularity, but also endow the c-completion with a structure of Lorentzian metric space by itself. We also prove that the c-completion constitutes a well-suited extension of the original space, which really completes it in a precise sense and becomes sensible to certain causal properties of that space. |
0908.1295 | Sanjit Das | Sanjit Das, Kartik Prabhu, Sayan Kar | Ricci flow of unwarped and warped product manifolds | 25 pages, 25 figures, some figures replaced | Int.J.Geom.Meth.Mod.Phys.07:837-856,2010 | 10.1142/S0219887810004579 | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyse Ricci flow (normalised/un-normalised) of product manifolds
--unwarped as well as warped, through a study of generic examples. First, we
investigate such flows for the unwarped scenario with manifolds of the type
$\mathbb S^n\times \mathbb S^m$, $\mathbb S^n\times \mathbb H^m$, $\mathbb
H^m\times \mathbb H^n$ and also, similar multiple products. We are able to
single out generic features such as singularity formation, isotropisation at
particular values of the flow parameter and evolution characteristics.
Subsequently, motivated by warped braneworlds and extra dimensions, we look at
Ricci flows of warped spacetimes. Here, we are able to find analytic solutions
for a special case by variable separation. For others we numerically solve the
equations (for both the forward and backward flow) and draw certain useful
inferences about the evolution of the warp factor, the scalar curvature as well
the occurence of singularities at finite values of the flow parameter. We also
investigate the dependence of the singularities of the flow on the inital
conditions. We expect our results to be useful in any physical/mathematical
context where such product manifolds may arise.
| [
{
"created": "Mon, 10 Aug 2009 10:28:50 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Sep 2009 12:07:40 GMT",
"version": "v2"
}
] | 2011-05-09 | [
[
"Das",
"Sanjit",
""
],
[
"Prabhu",
"Kartik",
""
],
[
"Kar",
"Sayan",
""
]
] | We analyse Ricci flow (normalised/un-normalised) of product manifolds --unwarped as well as warped, through a study of generic examples. First, we investigate such flows for the unwarped scenario with manifolds of the type $\mathbb S^n\times \mathbb S^m$, $\mathbb S^n\times \mathbb H^m$, $\mathbb H^m\times \mathbb H^n$ and also, similar multiple products. We are able to single out generic features such as singularity formation, isotropisation at particular values of the flow parameter and evolution characteristics. Subsequently, motivated by warped braneworlds and extra dimensions, we look at Ricci flows of warped spacetimes. Here, we are able to find analytic solutions for a special case by variable separation. For others we numerically solve the equations (for both the forward and backward flow) and draw certain useful inferences about the evolution of the warp factor, the scalar curvature as well the occurence of singularities at finite values of the flow parameter. We also investigate the dependence of the singularities of the flow on the inital conditions. We expect our results to be useful in any physical/mathematical context where such product manifolds may arise. |
1010.1792 | Valeri Frolov | Valeri Frolov | Applications of hidden symmetries to black hole physics | This is an extended version of the talks at NEB-14 conference
(June,Ioannina,Greece) and JGRG20 meeting (September, Kyoto, Japan) | null | 10.1088/1742-6596/283/1/012012 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work is a brief review of applications of hidden symmetries to black
hole physics. Symmetry is one of the most important concepts of the science. In
physics and mathematics the symmetry allows one to simplify a problem, and
often to make it solvable. According to the Noether theorem symmetries are
responsible for conservation laws. Besides evident (explicit) spacetime
symmetries, responsible for conservation of energy, momentum, and angular
momentum of a system, there also exist what is called hidden symmetries, which
are connected with higher order in momentum integrals of motion. A remarkable
fact is that black holes in four and higher dimensions always possess a set
(`tower') of explicit and hidden symmetries which make the equations of motion
of particles and light completely integrable. The paper gives a general review
of the recently obtained results. The main focus is on understanding why at all
black holes have something (symmetry) to hide.
| [
{
"created": "Fri, 8 Oct 2010 22:41:56 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Oct 2010 18:00:06 GMT",
"version": "v2"
}
] | 2015-05-20 | [
[
"Frolov",
"Valeri",
""
]
] | This work is a brief review of applications of hidden symmetries to black hole physics. Symmetry is one of the most important concepts of the science. In physics and mathematics the symmetry allows one to simplify a problem, and often to make it solvable. According to the Noether theorem symmetries are responsible for conservation laws. Besides evident (explicit) spacetime symmetries, responsible for conservation of energy, momentum, and angular momentum of a system, there also exist what is called hidden symmetries, which are connected with higher order in momentum integrals of motion. A remarkable fact is that black holes in four and higher dimensions always possess a set (`tower') of explicit and hidden symmetries which make the equations of motion of particles and light completely integrable. The paper gives a general review of the recently obtained results. The main focus is on understanding why at all black holes have something (symmetry) to hide. |
gr-qc/9912109 | Georgii Alekseev | G.A.Alekseev | Monodromy transform approach to solution of the Ernst equations in
General Relativity | 4 pages, 1 figure, LaTeX2e; based on a talk given at the
`International European Conference on Gravitation: Journ\'ees Relativistes
99.' Weimar, Germany, 12 - 17 Sep 1999; as submitted to Annalen der Physik
(Leipzig) | null | null | null | gr-qc math-ph math.MP nlin.SI solv-int | null | The approach, referred to as "monodromy transform", provides some general
base for solution of all known integrable space - time symmetry reductions of
Einstein equations for the case of pure vacuum gravitational fields, in the
presence of gravitationally interacting massless fields, as well as for some
string theory induced gravity models. In this communication we present the key
points of this approach, applied to Einstein equations for vacuum and to
Einstein - Maxwell equations for electrovacuum fields in the cases, reducible
to the known Ernst equations. Definition of the monodromy data, formulation and
solution of the direct and inverse problems of the monodromy transform, a proof
of existence and uniqueness of their solutions, the structure of the basic
linear singular integral equations and their regularizations, which lead to the
equations of (quasi-)Fredholm type are also discussed. A construction of
general local solution of these equations is given in terms of homogeneously
convergent functional series.
| [
{
"created": "Mon, 27 Dec 1999 18:31:46 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Alekseev",
"G. A.",
""
]
] | The approach, referred to as "monodromy transform", provides some general base for solution of all known integrable space - time symmetry reductions of Einstein equations for the case of pure vacuum gravitational fields, in the presence of gravitationally interacting massless fields, as well as for some string theory induced gravity models. In this communication we present the key points of this approach, applied to Einstein equations for vacuum and to Einstein - Maxwell equations for electrovacuum fields in the cases, reducible to the known Ernst equations. Definition of the monodromy data, formulation and solution of the direct and inverse problems of the monodromy transform, a proof of existence and uniqueness of their solutions, the structure of the basic linear singular integral equations and their regularizations, which lead to the equations of (quasi-)Fredholm type are also discussed. A construction of general local solution of these equations is given in terms of homogeneously convergent functional series. |
1107.2025 | Bibekananda Nayak jr | Bibekananda Nayak and Mubasher Jamil | Effect of Vacuum Energy on Evolution of Primordial Black Holes in
Einstein Gravity | 9 pages, 3 figures | Phys. Lett. B Volume 709, Issue 3 (2012)118-122 | 10.1016/j.physletb.2012.02.010 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the evolution of primordail black holes by considering present
universe is no more matter dominated rather vacuum energy dominated. We also
consider the accretion of radiation, matter and vacuum energy during respective
dominance period. In this scenario, we found that radiation accretion
efficiency should be less than 0.366 and accretion rate is much larger than
previous analysis by B. Nayak et al. \cite{ns}. Thus here primordial black
holes live longer than previous works \cite{ns}. Again matter accretion
slightly increases the mass and lifetime of primordial black holes. However,
the vacuum energy accretion is slightly complicated one, where accretion is
possible only upto a critical time. This critical time depends on the values of
accretion efficiency and formation time. If a primordial black hole lives
beyond critical time, then its lifespan increases due to vacuum energy
accretion. But for presently evaporating primordial black holes, critical time
comes much later than their evaporating time and thus vacuum energy could not
affect those primordial black holes. We again found that the constraints on the
initial mass fraction of PBH obtained from the $\gamma$-ray background limit
becomes stronger in the presence of vacuum energy.
| [
{
"created": "Mon, 11 Jul 2011 13:34:12 GMT",
"version": "v1"
}
] | 2012-03-05 | [
[
"Nayak",
"Bibekananda",
""
],
[
"Jamil",
"Mubasher",
""
]
] | We study the evolution of primordail black holes by considering present universe is no more matter dominated rather vacuum energy dominated. We also consider the accretion of radiation, matter and vacuum energy during respective dominance period. In this scenario, we found that radiation accretion efficiency should be less than 0.366 and accretion rate is much larger than previous analysis by B. Nayak et al. \cite{ns}. Thus here primordial black holes live longer than previous works \cite{ns}. Again matter accretion slightly increases the mass and lifetime of primordial black holes. However, the vacuum energy accretion is slightly complicated one, where accretion is possible only upto a critical time. This critical time depends on the values of accretion efficiency and formation time. If a primordial black hole lives beyond critical time, then its lifespan increases due to vacuum energy accretion. But for presently evaporating primordial black holes, critical time comes much later than their evaporating time and thus vacuum energy could not affect those primordial black holes. We again found that the constraints on the initial mass fraction of PBH obtained from the $\gamma$-ray background limit becomes stronger in the presence of vacuum energy. |
gr-qc/0105038 | Piotr Jaranowski | Thibault Damour, Piotr Jaranowski, and Gerhard Sch\"afer | Dimensional regularization of the gravitational interaction of point
masses | REVTeX, 8 pages, 1 figure; submitted to Phys. Lett. B | Phys.Lett.B513:147-155,2001 | 10.1016/S0370-2693(01)00642-6 | IHES/P/01/19 | gr-qc hep-th | null | We show how to use dimensional regularization to determine, within the
Arnowitt-Deser-Misner canonical formalism, the reduced Hamiltonian describing
the dynamics of two gravitationally interacting point masses. Implementing, at
the third post-Newtonian (3PN) accuracy, our procedure we find that dimensional
continuation yields a finite, unambiguous (no pole part) 3PN Hamiltonian which
uniquely determines the heretofore ambiguous ``static'' parameter: namely,
$\omega_s=0$. Our work also provides a remarkable check of the perturbative
consistency (compatibility with gauge symmetry) of dimensional continuation
through a direct calculation of the ``kinetic'' parameter $\omega_k$, giving
the unique answer compatible with global Poincar\'e invariance
($\omega_k={41/24}$) by summing $\sim50$ different dimensionally continued
contributions.
| [
{
"created": "Fri, 11 May 2001 08:01:53 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Damour",
"Thibault",
""
],
[
"Jaranowski",
"Piotr",
""
],
[
"Schäfer",
"Gerhard",
""
]
] | We show how to use dimensional regularization to determine, within the Arnowitt-Deser-Misner canonical formalism, the reduced Hamiltonian describing the dynamics of two gravitationally interacting point masses. Implementing, at the third post-Newtonian (3PN) accuracy, our procedure we find that dimensional continuation yields a finite, unambiguous (no pole part) 3PN Hamiltonian which uniquely determines the heretofore ambiguous ``static'' parameter: namely, $\omega_s=0$. Our work also provides a remarkable check of the perturbative consistency (compatibility with gauge symmetry) of dimensional continuation through a direct calculation of the ``kinetic'' parameter $\omega_k$, giving the unique answer compatible with global Poincar\'e invariance ($\omega_k={41/24}$) by summing $\sim50$ different dimensionally continued contributions. |
2005.05757 | Naresh Dadhich | Naresh Dadhich | On causal structure of $4D$-Einstein-Gauss-Bonnet black hole | 4 pages, no figures, References added, matches with the published
version | Eur. Phys. J. {\bf C80}, 832 (2020) | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The recently proposed effective equation of motion for the $4D$-
Einstein-Gauss-Bonnet gravity admits a static black hole solution that has,
like the Rissner-Nordstr\"{o}m charged black hole, two horizons instead of one
for the Schwarzschild black hole. This means that the central singularity is
timelike instead of spacelike. It should though be noted that in $D\geq5$, the
solution always admits only one horizon like the Schwarzshild solution. In the
equation defining the horizon, the rescaled Gauss-Bonnet coupling constant
appears as a new 'gravitational charge' with a repulsive effect to cause in
addition to event horizon a Cauchy horizon. Thus it radically alters the causal
structure of the black hole.
| [
{
"created": "Mon, 11 May 2020 11:39:23 GMT",
"version": "v1"
},
{
"created": "Sat, 16 May 2020 11:35:18 GMT",
"version": "v2"
},
{
"created": "Fri, 11 Sep 2020 03:53:49 GMT",
"version": "v3"
}
] | 2020-09-14 | [
[
"Dadhich",
"Naresh",
""
]
] | The recently proposed effective equation of motion for the $4D$- Einstein-Gauss-Bonnet gravity admits a static black hole solution that has, like the Rissner-Nordstr\"{o}m charged black hole, two horizons instead of one for the Schwarzschild black hole. This means that the central singularity is timelike instead of spacelike. It should though be noted that in $D\geq5$, the solution always admits only one horizon like the Schwarzshild solution. In the equation defining the horizon, the rescaled Gauss-Bonnet coupling constant appears as a new 'gravitational charge' with a repulsive effect to cause in addition to event horizon a Cauchy horizon. Thus it radically alters the causal structure of the black hole. |
1905.08642 | Saeed Fakhry | M. Heydari-Fard, S. Fakhry and S. N. Hasani | Perihelion advance and trajectory of charged test particles in
Reissner-Nordstrom field via the higher-order geodesic deviations | 12 pages, 1 figure | Journal of Advances in High Energy Physics (2019) | 10.1155/2019/1879568 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | By using the higher-order geodesic deviation equations for charged particles,
we apply the method described by Kerner et.al. to calculate the perihelion
advance and trajectory of charged test particles in the Riessner-Nordstrom
spacetime. The effect of charge on the perihelion advance is studied and
compared the results with those obtained earlier via the perturbation method.
The advantage of this approximation method is to provide a way to calculate the
perihelion advance and orbit of planets in the vicinity of massive and compact
objects without considering Newtonian and post-Newtonian approximation.
| [
{
"created": "Mon, 20 May 2019 17:03:24 GMT",
"version": "v1"
}
] | 2019-06-05 | [
[
"Heydari-Fard",
"M.",
""
],
[
"Fakhry",
"S.",
""
],
[
"Hasani",
"S. N.",
""
]
] | By using the higher-order geodesic deviation equations for charged particles, we apply the method described by Kerner et.al. to calculate the perihelion advance and trajectory of charged test particles in the Riessner-Nordstrom spacetime. The effect of charge on the perihelion advance is studied and compared the results with those obtained earlier via the perturbation method. The advantage of this approximation method is to provide a way to calculate the perihelion advance and orbit of planets in the vicinity of massive and compact objects without considering Newtonian and post-Newtonian approximation. |
2302.14480 | Peter M\'esz\'aros | Peter M\'esz\'aros | Evolution of perturbations in a universe with exotic solid-like matter | 19 pages, 3 figures | Physics of the Dark Universe 42 (2023) 101297 | 10.1016/j.dark.2023.101297 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study cosmological perturbations in a universe with only one matter
component described by a triplet of fields. Configuration of these fields is
the same as for body coordinates of a solid, and they enter the matter
Lagrangian only through the kinetic term. We restrict ourselves only to cases
with constant pressure to energy density ratio $w$. Superhorizon perturbations
have no constant modes with scalar vector and tensor perturbations decaying or
growing at different rates, and in cases with pressure to energy density ratio
$w>(19-8\sqrt{7})/3\dot{=}-0.722$ perturbations propagate with superluminal
sound speed. Regarding our universe, these results illustrate possible
challenges with comparing the observational data to models similar to solid
inflation, if the inflation is followed by a period during which the studied
model is a sufficiently good approximation.
| [
{
"created": "Tue, 28 Feb 2023 10:38:39 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Aug 2023 08:28:35 GMT",
"version": "v2"
}
] | 2023-08-15 | [
[
"Mészáros",
"Peter",
""
]
] | We study cosmological perturbations in a universe with only one matter component described by a triplet of fields. Configuration of these fields is the same as for body coordinates of a solid, and they enter the matter Lagrangian only through the kinetic term. We restrict ourselves only to cases with constant pressure to energy density ratio $w$. Superhorizon perturbations have no constant modes with scalar vector and tensor perturbations decaying or growing at different rates, and in cases with pressure to energy density ratio $w>(19-8\sqrt{7})/3\dot{=}-0.722$ perturbations propagate with superluminal sound speed. Regarding our universe, these results illustrate possible challenges with comparing the observational data to models similar to solid inflation, if the inflation is followed by a period during which the studied model is a sufficiently good approximation. |
gr-qc/9906091 | Yutaka Hosotani | Jefferson Bjoraker and Yutaka Hosotani | Stable monopole and dyon solutions in the Einstein-Yang-Mills theory in
asymptotically anti-de Sitter Space | 9 pages with 5 figures. Revised version. To appear in Phys Rev Lett | Phys.Rev.Lett. 84 (2000) 1853 | 10.1103/PhysRevLett.84.1853 | UMN-TH-1803/99, NUC-MINN-99/13-T | gr-qc hep-th | null | A continuum of new monopole and dyon solutions in the Einstein-Yang-Mills
theory in asymptotically anti-de Sitter space are found. They are regular
everywhere and specified with their mass, and non-Abelian electric and magnetic
charges. A class of monopole solutions which have no node in non-Abelian
magnetic fields are shown to be stable against spherically symmetric linear
perturbations.
| [
{
"created": "Wed, 23 Jun 1999 04:28:53 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Aug 1999 20:45:23 GMT",
"version": "v2"
},
{
"created": "Tue, 14 Dec 1999 17:08:13 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Bjoraker",
"Jefferson",
""
],
[
"Hosotani",
"Yutaka",
""
]
] | A continuum of new monopole and dyon solutions in the Einstein-Yang-Mills theory in asymptotically anti-de Sitter space are found. They are regular everywhere and specified with their mass, and non-Abelian electric and magnetic charges. A class of monopole solutions which have no node in non-Abelian magnetic fields are shown to be stable against spherically symmetric linear perturbations. |
1909.08199 | S. Kalyana Rama | S. Kalyana Rama | LQ Stars : Modifying the Tolman -- Oppenheimer -- Volkoff equations a la
LQC | Latex file. 26 pages | null | null | IMSc/2019/09/07 | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We rewrite the Tolman -- Oppenheimer -- Volkoff (TOV) equations for four and
higher dimensional static spherically symmetric stars so that they resemble the
equations for anisotropic cosmology. This becomes possible by treating the
curvature terms of the sphere as part of the matter sector. Comparing then with
the effective equations in the Loop Quantum Cosmology -- inspired models, we
propose analogous modifications to the TOV equations which contain one
arbitrary function. A linear function gives the TOV equations. If the function
and all its derivatives are finite then the solutions are non singular. For
$sin \; x \;$, an `image star' appears beyond the central region of maximal
pressures in the original star. This is evocative of a bouncing universe in
Loop Quantum Cosmology. We discuss possible observational consequences of these
features.
| [
{
"created": "Wed, 18 Sep 2019 03:42:45 GMT",
"version": "v1"
}
] | 2019-09-19 | [
[
"Rama",
"S. Kalyana",
""
]
] | We rewrite the Tolman -- Oppenheimer -- Volkoff (TOV) equations for four and higher dimensional static spherically symmetric stars so that they resemble the equations for anisotropic cosmology. This becomes possible by treating the curvature terms of the sphere as part of the matter sector. Comparing then with the effective equations in the Loop Quantum Cosmology -- inspired models, we propose analogous modifications to the TOV equations which contain one arbitrary function. A linear function gives the TOV equations. If the function and all its derivatives are finite then the solutions are non singular. For $sin \; x \;$, an `image star' appears beyond the central region of maximal pressures in the original star. This is evocative of a bouncing universe in Loop Quantum Cosmology. We discuss possible observational consequences of these features. |
gr-qc/0007079 | Somasri Sen | S. Sen and T. R. Seshadri | Self interacting Brans Dicke cosmology and Quintessence | 8pages, 5 figures, PRD style, some changes are made, figures added,
reference added. To be published in Int. J. Mod. Phys. D | Int.J.Mod.Phys. D12 (2003) 445-460 | 10.1142/S0218271803003049 | MRI-PHY/P20000532 | gr-qc astro-ph | null | Recent cosmological observations reveal that we are living in a flat
accelerated expanding universe. In this work we have investigated the nature of
the potential compatible with the power law expansion of the universe in a self
interacting Brans Dicke cosmology with a perfect fluid background and have
analyzed whether this potential supports the accelerated expansion. It is found
that positive power law potential is relevant in this scenario and can drive
accelerated expansion for negative Brans Dicke coupling parameter $\omega$. The
evolution of the density perturbation is also analyzed in this scenerio and is
seen that the model allows growing modes for negative $\omega$.
| [
{
"created": "Sat, 29 Jul 2000 07:15:05 GMT",
"version": "v1"
},
{
"created": "Mon, 31 Dec 2001 13:09:57 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Sen",
"S.",
""
],
[
"Seshadri",
"T. R.",
""
]
] | Recent cosmological observations reveal that we are living in a flat accelerated expanding universe. In this work we have investigated the nature of the potential compatible with the power law expansion of the universe in a self interacting Brans Dicke cosmology with a perfect fluid background and have analyzed whether this potential supports the accelerated expansion. It is found that positive power law potential is relevant in this scenario and can drive accelerated expansion for negative Brans Dicke coupling parameter $\omega$. The evolution of the density perturbation is also analyzed in this scenerio and is seen that the model allows growing modes for negative $\omega$. |
gr-qc/0508083 | Sugumi Kanno | Jiro Soda, Sugumi Kanno | Braneworld Cosmological Perturbation Theory at Low Energy | 10 pages, Based on a talk presented at ACRGR4, the 4th Australasian
Conference on General Relativity and Gravitation, Monash University,
Melbourne, January 2004. To appear in the proceedings, in General Relativity
and Gravitation | Gen.Rel.Grav.37:1621-1628,2005 | 10.1007/s10714-005-0139-3 | null | gr-qc | null | Homogeneous cosmology in the braneworld can be studied without solving bulk
equations of motion explicitly. The reason is simply because the symmetry of
the spacetime restricts possible corrections in the 4-dimensional effective
equations of motion. It would be great if we could analyze cosmological
perturbations without solving the bulk. For this purpose, we combine the
geometrical approach and the low energy gradient expansion method to derive the
4-dimensional effective action. Given our effective action, the standard
procedure to obtain the cosmological perturbation theory can be utilized and
the temperature anisotropy of the cosmic background radiation can be computed
without solving the bulk equations of motion explicitly.
| [
{
"created": "Sat, 20 Aug 2005 07:28:20 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Soda",
"Jiro",
""
],
[
"Kanno",
"Sugumi",
""
]
] | Homogeneous cosmology in the braneworld can be studied without solving bulk equations of motion explicitly. The reason is simply because the symmetry of the spacetime restricts possible corrections in the 4-dimensional effective equations of motion. It would be great if we could analyze cosmological perturbations without solving the bulk. For this purpose, we combine the geometrical approach and the low energy gradient expansion method to derive the 4-dimensional effective action. Given our effective action, the standard procedure to obtain the cosmological perturbation theory can be utilized and the temperature anisotropy of the cosmic background radiation can be computed without solving the bulk equations of motion explicitly. |
gr-qc/0204043 | Sascha Husa | Sascha Husa | Problems and Successes in the Numerical Approach to the Conformal Field
Equations | 20 pages, to appear in the proceedings of the conference ``The
Conformal Structure of Spacetimes: Geometry, Analysis, Numerics'', ed. by J.
Frauendiener and H. Friedrich, to be published by Springer Verlag, Lecture
Notes in Physics series | Lect.Notes Phys. 604 (2002) 239-260 | null | AEI-2002-030 | gr-qc | null | This talk reports on the status of an approach to the numerical study of
isolated systems with the conformal field equations. We first describe the
algorithms used in a code which has been developed at AEI in the last years,
and discuss a milestone result obtained by Huebner. Then we present more recent
results as examples to sketch the problems we face in the conformal approach to
numerical relativity and outline a possible roadmap toward making this approach
a practical tool.
| [
{
"created": "Fri, 12 Apr 2002 09:28:29 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Husa",
"Sascha",
""
]
] | This talk reports on the status of an approach to the numerical study of isolated systems with the conformal field equations. We first describe the algorithms used in a code which has been developed at AEI in the last years, and discuss a milestone result obtained by Huebner. Then we present more recent results as examples to sketch the problems we face in the conformal approach to numerical relativity and outline a possible roadmap toward making this approach a practical tool. |
gr-qc/9811060 | Francesco Belgiorno | F.Belgiorno and M.Martellini | Quantum properties of the electron field in Kerr-Newman black hole
manifolds | 9 pages, uses revtex | Phys.Lett. B453 (1999) 17-22 | 10.1016/S0370-2693(99)00313-5 | null | gr-qc | null | We study some spectral features of the one-particle electron Hamiltonian
obtained by separating the Dirac equation in a Kerr-Newman black hole
background. We find that the essential spectrum includes the whole real line.
As a consequence, there is no gap in the spectrum and discrete eigenvalues are
not allowed for any value of the black hole charge $Q$ and angular momentum
$J$. Our spectral analysis will be also related to the dissipation of the black
hole angular momentum and charge.
| [
{
"created": "Wed, 18 Nov 1998 14:36:01 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Belgiorno",
"F.",
""
],
[
"Martellini",
"M.",
""
]
] | We study some spectral features of the one-particle electron Hamiltonian obtained by separating the Dirac equation in a Kerr-Newman black hole background. We find that the essential spectrum includes the whole real line. As a consequence, there is no gap in the spectrum and discrete eigenvalues are not allowed for any value of the black hole charge $Q$ and angular momentum $J$. Our spectral analysis will be also related to the dissipation of the black hole angular momentum and charge. |
1010.5513 | Aron Wall | Aron C. Wall | The Generalized Second Law implies a Quantum Singularity Theorem | 46 pages, 8 figures. v2: discussion of global hyperbolicity revised
(4.1, 5.2), more comments on AdS. v3: major revisions including change of
title. v4: similar to published version, but with corrections to plan of
paper (1) and definition of global hyperbolicity (3.2). v5: fixed proof of
Thm. 1, changed wording of Thm. 3 & proof of Thm. 4, revised Sec. 5.2, new
footnotes | Class. Quantum Grav. 30, 165003 (2013) | 10.1088/0264-9381/30/16/165003 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The generalized second law can be used to prove a singularity theorem, by
generalizing the notion of a trapped surface to quantum situations. Like
Penrose's original singularity theorem, it implies that spacetime is null
geodesically incomplete inside black holes, and to the past of spatially
infinite Friedmann--Robertson--Walker cosmologies. If space is finite instead,
the generalized second law requires that there only be a finite amount of
entropy producing processes in the past, unless there is a reversal of the
arrow of time. In asymptotically flat spacetime, the generalized second law
also rules out traversable wormholes, negative masses, and other forms of
faster-than-light travel between asymptotic regions, as well as closed timelike
curves. Furthermore it is impossible to form baby universes which eventually
become independent of the mother universe, or to restart inflation. Since the
semiclassical approximation is used only in regions with low curvature, it is
argued that the results may hold in full quantum gravity. An introductory
section describes the second law and its time-reverse, in ordinary and
generalized thermodynamics, using either the fine-grained or the coarse-grained
entropy. (The fine-grained version is used in all results except those relating
to the arrow of time.) A proof of the coarse-grained ordinary second law is
given.
| [
{
"created": "Tue, 26 Oct 2010 20:42:18 GMT",
"version": "v1"
},
{
"created": "Sun, 20 Feb 2011 03:04:19 GMT",
"version": "v2"
},
{
"created": "Thu, 24 Jan 2013 07:09:11 GMT",
"version": "v3"
},
{
"created": "Tue, 13 Aug 2013 21:50:09 GMT",
"version": "v4"
},
{
"created": "Tue, 6 Dec 2016 18:48:47 GMT",
"version": "v5"
}
] | 2016-12-07 | [
[
"Wall",
"Aron C.",
""
]
] | The generalized second law can be used to prove a singularity theorem, by generalizing the notion of a trapped surface to quantum situations. Like Penrose's original singularity theorem, it implies that spacetime is null geodesically incomplete inside black holes, and to the past of spatially infinite Friedmann--Robertson--Walker cosmologies. If space is finite instead, the generalized second law requires that there only be a finite amount of entropy producing processes in the past, unless there is a reversal of the arrow of time. In asymptotically flat spacetime, the generalized second law also rules out traversable wormholes, negative masses, and other forms of faster-than-light travel between asymptotic regions, as well as closed timelike curves. Furthermore it is impossible to form baby universes which eventually become independent of the mother universe, or to restart inflation. Since the semiclassical approximation is used only in regions with low curvature, it is argued that the results may hold in full quantum gravity. An introductory section describes the second law and its time-reverse, in ordinary and generalized thermodynamics, using either the fine-grained or the coarse-grained entropy. (The fine-grained version is used in all results except those relating to the arrow of time.) A proof of the coarse-grained ordinary second law is given. |
1712.00612 | Yury F. Pirogov | Yuriy F. Pirogov | Quartet-metric gravity and dark components of the Universe | Minor corrections. 7 pages. Report presented at the XXXI Intern.
Workshop on HEP, Protvino, 5-7 July 2017 | Int. J. Mod. Phys.: Conf. Series, 47, 1860101 (2018) | 10.1142/S2010194518601011 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the report there are presented the general frameworks for the
quartet-metric gravity based upon the two physical concepts. First, there exist
in space-time the distinct dynamical coordinates, given by a scalar quartet,
playing the role of the Higgs fields for gravity. Second, the physical gravity
fields arising due to the spontaneous symmetry breaking serve as the dark
components of the Universe. It is argued that the mere admixture to metric of
the scalar quartet may give rise to an extremely wide spectrum of the emergent
gravity phenomena beyond General Relativity (GR). Developing the proposed
frameworks further to find out the next-to-GR theory of gravity is a challenge.
| [
{
"created": "Sat, 2 Dec 2017 14:30:41 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Dec 2017 14:32:14 GMT",
"version": "v2"
}
] | 2019-03-19 | [
[
"Pirogov",
"Yuriy F.",
""
]
] | In the report there are presented the general frameworks for the quartet-metric gravity based upon the two physical concepts. First, there exist in space-time the distinct dynamical coordinates, given by a scalar quartet, playing the role of the Higgs fields for gravity. Second, the physical gravity fields arising due to the spontaneous symmetry breaking serve as the dark components of the Universe. It is argued that the mere admixture to metric of the scalar quartet may give rise to an extremely wide spectrum of the emergent gravity phenomena beyond General Relativity (GR). Developing the proposed frameworks further to find out the next-to-GR theory of gravity is a challenge. |
1502.07395 | Oleg Titov | O. Titov, A. Girdiuk | The deflection of light induced by the Sun's gravitational field and
measured with geodetic VLBI | null | Proc. of "Journees-2014" meeting (edited by Z. Malkin and N.
Capitaine), pp. 75-78 | null | null | gr-qc astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | The Sun's gravitational field deflects the apparent positions of close
objects in accordance with the formulae of general relativity. Optical
astrometry is used to test the prediction, but only with the stars close to the
Sun and only during total Solar eclipses. Geodetic Very Long Baseline
Interferometry (VLBI) is capable of measuring the deflection of the light from
distant radio sources anytime and across the whole sky. We show that the effect
of light deflection is equivalent to the gravitational delay calculated during
the reduction of VLBI data. All reference radio sources display an annual
circular motion with the magnitude proportional to their ecliptic latitude. In
particular, radio sources near the ecliptic pole draw an annual circle with
magnitude of 4 mas. This effect could be easily measured with the current
precision of the geodetic VLBI data.
| [
{
"created": "Wed, 25 Feb 2015 23:03:18 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Nov 2015 02:54:21 GMT",
"version": "v2"
}
] | 2015-11-03 | [
[
"Titov",
"O.",
""
],
[
"Girdiuk",
"A.",
""
]
] | The Sun's gravitational field deflects the apparent positions of close objects in accordance with the formulae of general relativity. Optical astrometry is used to test the prediction, but only with the stars close to the Sun and only during total Solar eclipses. Geodetic Very Long Baseline Interferometry (VLBI) is capable of measuring the deflection of the light from distant radio sources anytime and across the whole sky. We show that the effect of light deflection is equivalent to the gravitational delay calculated during the reduction of VLBI data. All reference radio sources display an annual circular motion with the magnitude proportional to their ecliptic latitude. In particular, radio sources near the ecliptic pole draw an annual circle with magnitude of 4 mas. This effect could be easily measured with the current precision of the geodetic VLBI data. |
1809.09183 | Jorge Pullin | Jorge Pullin and Parampreet Singh | Report on session QG3 of the 15th Marcel Grossmann Meeting | 5 pages, no figures, to appear in the conference proceedings | null | 10.1142/13149 | LSU-REL-092418 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We summarize the talks presented at the QG3 session (loop quantum gravity:
cosmology and black holes) of the 15th Marcel Grossmann Meeting held in Rome,
Italy on July 1-7 2018.
| [
{
"created": "Mon, 24 Sep 2018 19:34:31 GMT",
"version": "v1"
}
] | 2023-01-27 | [
[
"Pullin",
"Jorge",
""
],
[
"Singh",
"Parampreet",
""
]
] | We summarize the talks presented at the QG3 session (loop quantum gravity: cosmology and black holes) of the 15th Marcel Grossmann Meeting held in Rome, Italy on July 1-7 2018. |
2206.15333 | Yu-Xiao Liu | Yu-Qiang Liu, Yu-Qi Dong, and Yu-Xiao Liu | Classification of Gravitational Waves in Higher-dimensional Space-time
and Possibility of Observation | 19 pages, 4 figures | Eur. Phys. J. C 83, 857 (2023) | 10.1140/epjc/s10052-023-11944-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The direct detection of gravitational waves opens the possibility to test
general relativity and its alternatives in the strong field regime. Here we
focus on the test of the existence of extra dimensions. The classification of
gravitational waves in metric gravity theories according to their polarizations
in higher-dimensional space-time and the possible observation of these
polarizations in 3-dimensional subspace are discussed in this work. And we show
that the difference in the response of gravitational waves in detectors with
and without extra dimensions can serve as evidence for the existence of extra
dimensions.
| [
{
"created": "Thu, 30 Jun 2022 15:01:02 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Feb 2024 11:42:43 GMT",
"version": "v2"
}
] | 2024-02-26 | [
[
"Liu",
"Yu-Qiang",
""
],
[
"Dong",
"Yu-Qi",
""
],
[
"Liu",
"Yu-Xiao",
""
]
] | The direct detection of gravitational waves opens the possibility to test general relativity and its alternatives in the strong field regime. Here we focus on the test of the existence of extra dimensions. The classification of gravitational waves in metric gravity theories according to their polarizations in higher-dimensional space-time and the possible observation of these polarizations in 3-dimensional subspace are discussed in this work. And we show that the difference in the response of gravitational waves in detectors with and without extra dimensions can serve as evidence for the existence of extra dimensions. |
0803.2530 | Stanislav Hled\'ik | Zden\v{e}k Stuchl\'ik | Spherically Symmetric Static Configurations of Uniform Density in
Spacetimes with a Non-Zero Cosmological Constant | 11 pages | ActaPhys.Slov.50:219-228,2000 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Interior solutions of Einstein's equations with a non-zero cosmological
constant are given for static and spherically symmetric configurations of
uniform density. The metric tensor and pressure are determined for both
positive and negative values of the cosmological constant. Limits on the outer
radius of the interior solutions are established. It is shown that, contrary to
the cases of the limits on the interior Schwarzschild and Reissner--Nordstr\"om
solutions with a zero cosmological constant, these limits do not fully coincide
with the conditions of embeddability of the optical reference geometry
associated with the exterior (vacuum) Schwarzschild--de Sitter spacetime.
| [
{
"created": "Mon, 17 Mar 2008 21:03:52 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Stuchlík",
"Zdeněk",
""
]
] | Interior solutions of Einstein's equations with a non-zero cosmological constant are given for static and spherically symmetric configurations of uniform density. The metric tensor and pressure are determined for both positive and negative values of the cosmological constant. Limits on the outer radius of the interior solutions are established. It is shown that, contrary to the cases of the limits on the interior Schwarzschild and Reissner--Nordstr\"om solutions with a zero cosmological constant, these limits do not fully coincide with the conditions of embeddability of the optical reference geometry associated with the exterior (vacuum) Schwarzschild--de Sitter spacetime. |
2301.04334 | Merab Gogberashvili Prof | Merab Gogberashvili | Fixing cosmological constant on the event horizon | 5 pages, no figures | Eur. Phys. J. C 82 (2022) 1049 | 10.1140/epjc/s10052-022-11033-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Standard cosmological equations are written for the Hubble volume, while the
real boundary of space-time is the event horizon. Within the unimodular and
thermodynamic approaches to gravity, the dark energy term in cosmological
equations appears as an integration constant, which we fix at the event horizon
and obtain the observed value for the cosmological constant.
| [
{
"created": "Wed, 11 Jan 2023 07:07:31 GMT",
"version": "v1"
}
] | 2023-01-12 | [
[
"Gogberashvili",
"Merab",
""
]
] | Standard cosmological equations are written for the Hubble volume, while the real boundary of space-time is the event horizon. Within the unimodular and thermodynamic approaches to gravity, the dark energy term in cosmological equations appears as an integration constant, which we fix at the event horizon and obtain the observed value for the cosmological constant. |
1209.5128 | Radouane Gannouji | Radouane Gannouji | DGP black holes on the brane | 5 pages, 1 figure | Eur. Phys. J. C (2018) 78: 318 | 10.1140/epjc/s10052-018-5809-x | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find an exact solution on the brane for static black hole in the DGP
model. In the appropriate limit we recover the 2 known solutions, the
Schwarzschild and the Reissner-Nordstrom solutions with tidal charge. The
solution has 2 branches, which correspond asymptotically to de-Sitter or flat
Universe. Also we study the linear stability of the solutions. We find that the
Regge-Wheeler and the Zerilli potential are positive. Finally the dipole
perturbation is derived which corresponds to a linearization of a rotating
black hole solution on the brane.
| [
{
"created": "Sun, 23 Sep 2012 23:52:09 GMT",
"version": "v1"
}
] | 2018-04-24 | [
[
"Gannouji",
"Radouane",
""
]
] | We find an exact solution on the brane for static black hole in the DGP model. In the appropriate limit we recover the 2 known solutions, the Schwarzschild and the Reissner-Nordstrom solutions with tidal charge. The solution has 2 branches, which correspond asymptotically to de-Sitter or flat Universe. Also we study the linear stability of the solutions. We find that the Regge-Wheeler and the Zerilli potential are positive. Finally the dipole perturbation is derived which corresponds to a linearization of a rotating black hole solution on the brane. |
gr-qc/0007084 | V. Suneeta | T.R.Govindarajan and V.Suneeta | Quasi-normal modes of AdS black holes : A superpotential approach | LaTeX, 17 pages, 5 eps figures, 1 eepic figure, minor typos corrected | Class.Quant.Grav. 18 (2001) 265-276 | 10.1088/0264-9381/18/2/306 | IMSc/2000/07/37 | gr-qc hep-th | null | A novel method, based on superpotentials is proposed for obtaining the
quasi-normal modes of anti-de Sitter black holes. This is inspired by the case
of the three-dimensional BTZ black hole, where the quasi-normal modes can be
obtained exactly and are proportional to the surface gravity. Using this
approach, the quasi-normal modes of the five dimensional Schwarzschild
anti-deSitter black hole are computed numerically. The modes again seem to be
proportional to the surface gravity for very small and very large black holes.
They reflect the well-known instability of small black holes in anti-deSitter
space.
| [
{
"created": "Mon, 31 Jul 2000 15:06:36 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Oct 2000 15:24:16 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Govindarajan",
"T. R.",
""
],
[
"Suneeta",
"V.",
""
]
] | A novel method, based on superpotentials is proposed for obtaining the quasi-normal modes of anti-de Sitter black holes. This is inspired by the case of the three-dimensional BTZ black hole, where the quasi-normal modes can be obtained exactly and are proportional to the surface gravity. Using this approach, the quasi-normal modes of the five dimensional Schwarzschild anti-deSitter black hole are computed numerically. The modes again seem to be proportional to the surface gravity for very small and very large black holes. They reflect the well-known instability of small black holes in anti-deSitter space. |
1303.4350 | Felipe Falciano | E. Goulart and F. T. Falciano | Disformal invariance of Maxwell's field equations | 8 pages, no figures | Class. Quantum Grav. 30 (2013) 155020 | 10.1088/0264-9381/30/15/155020 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that Maxwell's electrodynamics in vacuum is invariant under active
transformations of the metric. These metrics are related by disformal mappings
induced by derivatives of the gauge vector $A_{\mu}$ such that the gauge
symmetry is preserved. Our results generalize the well known conformal
invariance of electrodynamics and characterize a new type of internal symmetry
of the theory. The group structure associated with these transformations is
also investigated in details.
| [
{
"created": "Mon, 18 Mar 2013 18:22:53 GMT",
"version": "v1"
}
] | 2013-07-17 | [
[
"Goulart",
"E.",
""
],
[
"Falciano",
"F. T.",
""
]
] | We show that Maxwell's electrodynamics in vacuum is invariant under active transformations of the metric. These metrics are related by disformal mappings induced by derivatives of the gauge vector $A_{\mu}$ such that the gauge symmetry is preserved. Our results generalize the well known conformal invariance of electrodynamics and characterize a new type of internal symmetry of the theory. The group structure associated with these transformations is also investigated in details. |
2211.17147 | Mohamed Ould El Hadj | Theo Torres, Mohamed Ould El Hadj, Shi-Qian Hu and Ruth Gregory | Regge pole description of scattering by dirty black holes | 23 pages, 15 figures | Phys. Rev. D 107, 064028 (2023) | 10.1103/PhysRevD.107.064028 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the problem of plane monochromatic scalar waves impinging upon a
Schwarzschild dirty black hole -- a Schwarzschild black hole surrounded by a
thin spherical shell of matter -- using the complex angular momentum approach.
We first recall general results concerning the differential scattering cross
section in the classical limit through a null geodesic analysis by exploring
different configurations of the shell. In particular, we show that dirty black
hole spacetimes may exhibit various critical effects for geometrical optics. We
compute the Regge pole spectrum for various shell configurations and show that
it exhibits two or three distinct branches of poles, labelled inner surface
waves, broad resonances and outer surface waves. In the latter, two
sub-families have been identified, the surface waves associated with the outer
light-ring and the creeping modes associated with the surface of the shell. We
show, using WKB analysis, that the position of the shell sets the real part of
the broad resonances while its energy-momentum and the discontinuity of the
potential at the shell's surface set their imaginary part. Next, we provide the
complex angular momentum representation of the differential scattering cross
section and examine the role of the different Regge pole branches. We compute
the differential scattering cross section for various configurations at several
frequencies and show a very good agreement with the partial-wave calculations.
Finally, we highlight the role of the critical effects, i.e., orbiting, glory,
grazing and rainbow scattering, and their impact on the differential scattering
cross section.
| [
{
"created": "Wed, 30 Nov 2022 16:35:16 GMT",
"version": "v1"
}
] | 2023-03-15 | [
[
"Torres",
"Theo",
""
],
[
"Hadj",
"Mohamed Ould El",
""
],
[
"Hu",
"Shi-Qian",
""
],
[
"Gregory",
"Ruth",
""
]
] | We study the problem of plane monochromatic scalar waves impinging upon a Schwarzschild dirty black hole -- a Schwarzschild black hole surrounded by a thin spherical shell of matter -- using the complex angular momentum approach. We first recall general results concerning the differential scattering cross section in the classical limit through a null geodesic analysis by exploring different configurations of the shell. In particular, we show that dirty black hole spacetimes may exhibit various critical effects for geometrical optics. We compute the Regge pole spectrum for various shell configurations and show that it exhibits two or three distinct branches of poles, labelled inner surface waves, broad resonances and outer surface waves. In the latter, two sub-families have been identified, the surface waves associated with the outer light-ring and the creeping modes associated with the surface of the shell. We show, using WKB analysis, that the position of the shell sets the real part of the broad resonances while its energy-momentum and the discontinuity of the potential at the shell's surface set their imaginary part. Next, we provide the complex angular momentum representation of the differential scattering cross section and examine the role of the different Regge pole branches. We compute the differential scattering cross section for various configurations at several frequencies and show a very good agreement with the partial-wave calculations. Finally, we highlight the role of the critical effects, i.e., orbiting, glory, grazing and rainbow scattering, and their impact on the differential scattering cross section. |
1501.03510 | Don N. Page | Don N. Page and Andrey A. Shoom | Local Invariants Vanishing on Stationary Horizons: A Diagnostic for
Locating Black Holes | 5 pages, LaTeX, additional material added, retitled at the suggestion
of the Physical Review Letters editor when accepting the paper | Phys. Rev. Lett. 114, 141102 (2015) | 10.1103/PhysRevLett.114.141102 | Alberta-Thy-1-15 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Inspired by the example of Abdelqader and Lake for the Kerr metric, we
construct local scalar polynomial curvature invariants that vanish on the
horizon of any stationary black hole: the squared norms of the wedge products
of n linearly independent gradients of scalar polynomial curvature invariants,
where n is the local cohomogeneity of the spacetime.
| [
{
"created": "Wed, 14 Jan 2015 21:04:59 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Jan 2015 19:52:16 GMT",
"version": "v2"
},
{
"created": "Wed, 11 Mar 2015 15:55:56 GMT",
"version": "v3"
},
{
"created": "Thu, 19 Mar 2015 18:00:56 GMT",
"version": "v4"
}
] | 2015-04-16 | [
[
"Page",
"Don N.",
""
],
[
"Shoom",
"Andrey A.",
""
]
] | Inspired by the example of Abdelqader and Lake for the Kerr metric, we construct local scalar polynomial curvature invariants that vanish on the horizon of any stationary black hole: the squared norms of the wedge products of n linearly independent gradients of scalar polynomial curvature invariants, where n is the local cohomogeneity of the spacetime. |
gr-qc/0604094 | Tomas Janssen | Tomas Janssen, Tomislav Prokopec (Utrecht U.) | Instabilities in the nonsymmetric theory of gravitation | 29 pages | Class.Quant.Grav. 23 (2006) 4967-4982 | 10.1088/0264-9381/23/15/015 | SPIN-06-15, ITP-UU-06-18 | gr-qc | null | We consider the linearized nonsymmetric theory of gravitation (NGT) within
the background of an expanding universe and near a Schwarzschild metric. We
show that the theory always develops instabilities unless the linearized
nonsymmetric lagrangian reduces to a particular simple form. This theory
contains a gauge invariant kinetic term, a mass term for the antisymmetric
metric-field and a coupling with the Ricci curvature scalar. This form cannot
be obtained within NGT. Next we discuss NGT beyond linearized level and
conjecture that the instabilities are not a relic of the linearization, but are
a general feature of the full theory. Finally we show that one cannot add
ad-hoc constraints to remove the instabilities as is possible with the
instabilities found in NGT by Clayton.
| [
{
"created": "Fri, 21 Apr 2006 13:25:30 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Janssen",
"Tomas",
"",
"Utrecht U."
],
[
"Prokopec",
"Tomislav",
"",
"Utrecht U."
]
] | We consider the linearized nonsymmetric theory of gravitation (NGT) within the background of an expanding universe and near a Schwarzschild metric. We show that the theory always develops instabilities unless the linearized nonsymmetric lagrangian reduces to a particular simple form. This theory contains a gauge invariant kinetic term, a mass term for the antisymmetric metric-field and a coupling with the Ricci curvature scalar. This form cannot be obtained within NGT. Next we discuss NGT beyond linearized level and conjecture that the instabilities are not a relic of the linearization, but are a general feature of the full theory. Finally we show that one cannot add ad-hoc constraints to remove the instabilities as is possible with the instabilities found in NGT by Clayton. |
2103.08104 | Wen-Biao Han | Song Li, Ahmadjon A. Abdujabbarov, Wen-Biao Han | Qualifying ringdown and shadow of black holes under general parametrized
metrics with photon orbits | 18 pages, 27 figures | Eur. Phys. J. C 81:649 (2021) | 10.1140/epjc/s10052-021-09445-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The motion of photons around black holes determines the shape of shadow and
match the ringdown properties of a perturbed black hole. Observations of
shadows and ringdown waveforms will reveal the nature of black holes. In this
paper, we study the motion of photons in a general parametrized metric beyond
the Kerr hypothesis. We investigated the radius and frequency of the photon
circular orbits on the equatorial plane and obtained fitted formula with varied
parameters. The Lyapunov exponent which connects to the decay rate of the
ringdown amplitude is also calculated. We also analyzed the shape of shadow
with full parameters of the generally axisymmetric metric. Our results imply
the potential constraint on black hole parameters by combining the Event
Horizon Telescope and gravitational wave observations in the future.
| [
{
"created": "Mon, 15 Mar 2021 02:47:10 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Jul 2021 07:02:30 GMT",
"version": "v2"
}
] | 2021-07-29 | [
[
"Li",
"Song",
""
],
[
"Abdujabbarov",
"Ahmadjon A.",
""
],
[
"Han",
"Wen-Biao",
""
]
] | The motion of photons around black holes determines the shape of shadow and match the ringdown properties of a perturbed black hole. Observations of shadows and ringdown waveforms will reveal the nature of black holes. In this paper, we study the motion of photons in a general parametrized metric beyond the Kerr hypothesis. We investigated the radius and frequency of the photon circular orbits on the equatorial plane and obtained fitted formula with varied parameters. The Lyapunov exponent which connects to the decay rate of the ringdown amplitude is also calculated. We also analyzed the shape of shadow with full parameters of the generally axisymmetric metric. Our results imply the potential constraint on black hole parameters by combining the Event Horizon Telescope and gravitational wave observations in the future. |
gr-qc/9605042 | Dr. Greg Comer | G. L. Comer (Saint Louis University), Nathalie Deruelle (DARC,
Observatoire de Paris) and David Langlois (DARC, Observatoire de Paris) | Long-wavelength iteration scheme and scalar-tensor gravity | 13 pages, requires REVTeX, submitted to Phys. Rev. D | Phys.Rev.D55:3497-3504,1997 | 10.1103/PhysRevD.55.3497 | null | gr-qc | null | Inhomogeneous and anisotropic cosmologies are modeled withing the framework
of scalar-tensor gravity theories. The inhomogeneities are calculated to
third-order in the so-called long-wavelength iteration scheme. We write the
solutions for general scalar coupling and discuss what happens to the
third-order terms when the scalar-tensor solution approaches at first-order the
general relativistic one. We work out in some detail the case of Brans-Dicke
coupling and determine the conditions for which the anisotropy and
inhomogeneity decay as time increases. The matter is taken to be that of
perfect fluid with a barotropic equation of state.
| [
{
"created": "Sun, 19 May 1996 16:08:27 GMT",
"version": "v1"
}
] | 2011-08-17 | [
[
"Comer",
"G. L.",
"",
"Saint Louis University"
],
[
"Deruelle",
"Nathalie",
"",
"DARC,\n Observatoire de Paris"
],
[
"Langlois",
"David",
"",
"DARC, Observatoire de Paris"
]
] | Inhomogeneous and anisotropic cosmologies are modeled withing the framework of scalar-tensor gravity theories. The inhomogeneities are calculated to third-order in the so-called long-wavelength iteration scheme. We write the solutions for general scalar coupling and discuss what happens to the third-order terms when the scalar-tensor solution approaches at first-order the general relativistic one. We work out in some detail the case of Brans-Dicke coupling and determine the conditions for which the anisotropy and inhomogeneity decay as time increases. The matter is taken to be that of perfect fluid with a barotropic equation of state. |
2408.05825 | Somayyeh Mahmoudi | S. Mahmoudi and S. H. Hendi | Gravitational Radiation in Generalized Brans Dicke Theory: Compact
Binary Systems | Accepted for Eur. Phys. J. C | null | null | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper investigates the generation and properties of
gravitational radiation within the framework of Generalized
Brans-Dicke (GBD) theory, with a specific emphasis on its
manifestation in compact binary systems. The primary focus of this study lies
in the
comprehensive exploration of gravitational radiation generated by
compact binaries. The energy momentum tensor and the associated
gravitational wave (GW) radiation power in GBD theory are
investigated, elucidating the relationship between these
fundamental concepts. Furthermore, detailed calculations are
provided for the GW radiation power originating from both tensor
fields and scalar fields. Based on our calculations, both scalar
fields contribute to GW radiation by producing dipole radiation.
We also study the period derivative of compact binaries in this
theory. By comparing with the observational data of the orbital
period derivative of the quasicircular white dwarf-neutron star
binary PSR J1012+5307, we put bounds on the two parameters of the
theory: the Brans-Dicke coupling parameter $\omega_{0}$ and the
mass of geometrical scalar field $m_f$, \textcolor{black}{resulting
in a lower bound $\omega_{0}>6.09723\times10^6$ for a massless BD
scalar field and the geometrical field whose mass is smaller than
$10^{-29} \text{GeV}$. The obtained bound on $\omega_0$ is two
orders of magnitude stricter than those derived from solar system
data.} Finally, we find the phase shift that GWs experience in the
frequency domain during their propagation.
| [
{
"created": "Sun, 11 Aug 2024 17:00:01 GMT",
"version": "v1"
}
] | 2024-08-13 | [
[
"Mahmoudi",
"S.",
""
],
[
"Hendi",
"S. H.",
""
]
] | This paper investigates the generation and properties of gravitational radiation within the framework of Generalized Brans-Dicke (GBD) theory, with a specific emphasis on its manifestation in compact binary systems. The primary focus of this study lies in the comprehensive exploration of gravitational radiation generated by compact binaries. The energy momentum tensor and the associated gravitational wave (GW) radiation power in GBD theory are investigated, elucidating the relationship between these fundamental concepts. Furthermore, detailed calculations are provided for the GW radiation power originating from both tensor fields and scalar fields. Based on our calculations, both scalar fields contribute to GW radiation by producing dipole radiation. We also study the period derivative of compact binaries in this theory. By comparing with the observational data of the orbital period derivative of the quasicircular white dwarf-neutron star binary PSR J1012+5307, we put bounds on the two parameters of the theory: the Brans-Dicke coupling parameter $\omega_{0}$ and the mass of geometrical scalar field $m_f$, \textcolor{black}{resulting in a lower bound $\omega_{0}>6.09723\times10^6$ for a massless BD scalar field and the geometrical field whose mass is smaller than $10^{-29} \text{GeV}$. The obtained bound on $\omega_0$ is two orders of magnitude stricter than those derived from solar system data.} Finally, we find the phase shift that GWs experience in the frequency domain during their propagation. |
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