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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1510.06820 | Evan Goetz | Evan Goetz and Keith Riles | Coherently combining short data segments for all-sky semi-coherent
continuous gravitational wave searches | 15 pages, 3 figures, 1 table | null | 10.1088/0264-9381/33/8/085007 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a method for coherently combining short data segments from
gravitational-wave detectors to improve the sensitivity of semi-coherent
searches for continuous gravitational waves. All-sky searches for continuous
gravitational waves from unknown sources are computationally limited. The
semi-coherent approach reduces the computational cost by dividing the entire
observation timespan into short segments to be analyzed coherently, then
combined together incoherently. Semi-coherent analyses that attempt to improve
sensitivity by coherently combining data from multiple detectors face a
computational challenge in accounting for uncertainties in signal parameters.
In this article, we lay out a technique to meet this challenge using summed
Fourier transform coefficients. Applying this technique to one all-sky search
algorithm called TwoSpect, we confirm that the sensitivity of all-sky,
semi-coherent searches can be improved by coherently combining the short data
segments. For misaligned detectors, however, this improvement requires careful
attention when marginalizing over unknown polarization parameters. In addition,
care must be taken in correcting for differential detector velocity due to the
Earth's rotation for high signal frequencies and widely separated detectors.
| [
{
"created": "Fri, 23 Oct 2015 03:41:49 GMT",
"version": "v1"
}
] | 2016-04-13 | [
[
"Goetz",
"Evan",
""
],
[
"Riles",
"Keith",
""
]
] | We present a method for coherently combining short data segments from gravitational-wave detectors to improve the sensitivity of semi-coherent searches for continuous gravitational waves. All-sky searches for continuous gravitational waves from unknown sources are computationally limited. The semi-coherent approach reduces the computational cost by dividing the entire observation timespan into short segments to be analyzed coherently, then combined together incoherently. Semi-coherent analyses that attempt to improve sensitivity by coherently combining data from multiple detectors face a computational challenge in accounting for uncertainties in signal parameters. In this article, we lay out a technique to meet this challenge using summed Fourier transform coefficients. Applying this technique to one all-sky search algorithm called TwoSpect, we confirm that the sensitivity of all-sky, semi-coherent searches can be improved by coherently combining the short data segments. For misaligned detectors, however, this improvement requires careful attention when marginalizing over unknown polarization parameters. In addition, care must be taken in correcting for differential detector velocity due to the Earth's rotation for high signal frequencies and widely separated detectors. |
gr-qc/9912011 | Martin Rainer | Martin Rainer | Is Loop Quantum Gravity a QFT ? | 10 pages, latex & AMS symb., presented at ERE 99 (Bilbao), v2: errors
& misprints corrected at beginning/end of sec.2, and in sec. 4 | null | null | null | gr-qc | null | We investigate up to which extend the kinematic setting of loop quantum
gravity can be fit into a diffeomorphism invariant setting of algebraic QFT
generalizing the Haag-Kastler setting of Wightman type QFT. The net of local
(Weyl-)algebras resulting from a spin network state of quantum geometry
immediately accommodates isotony and diffeomorphism covariance, and formulation
of causality becomes possible via of diffeomorphism invariant foliations of the
underlying manifold by cones. On a spatial horizon, quantum geometry becomes
asymptotically a genuine QFT with infinitely many degrees of freedom, if the
cylinder functions' supporting graphs intersect the inner boundary spheres in
an infinite number of punctures.
| [
{
"created": "Thu, 2 Dec 1999 16:29:41 GMT",
"version": "v1"
},
{
"created": "Mon, 31 Jan 2000 15:03:24 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Rainer",
"Martin",
""
]
] | We investigate up to which extend the kinematic setting of loop quantum gravity can be fit into a diffeomorphism invariant setting of algebraic QFT generalizing the Haag-Kastler setting of Wightman type QFT. The net of local (Weyl-)algebras resulting from a spin network state of quantum geometry immediately accommodates isotony and diffeomorphism covariance, and formulation of causality becomes possible via of diffeomorphism invariant foliations of the underlying manifold by cones. On a spatial horizon, quantum geometry becomes asymptotically a genuine QFT with infinitely many degrees of freedom, if the cylinder functions' supporting graphs intersect the inner boundary spheres in an infinite number of punctures. |
2106.10582 | Javier Rubio | Grigoris Panotopoulos, Javier Rubio, Il\'idio Lopes | On the impact of non-local gravity on compact stars | 19 pages, 4 figures, matches the version published in International
Journal of Modern Physics D | null | 10.1142/S0218271822501395 | null | gr-qc astro-ph.HE astro-ph.SR hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the impact of non-local modifications of General Relativity on
stellar structure. In particular, assuming an analytic distortion function and
specific equations of state, we made use of remnant stars to put qualitative
constraints on a parameter not directly restricted by solar system tests. Using
current data sets available for white dwarfs and strange quark stars candidates
we find that the most stringent bounds come from the objects displaying the
highest core densities, namely strange quark stars. Specifically, the
constraints obtained from this class of stars are three to four orders of
magnitude tighter than those obtained using white dwarfs.
| [
{
"created": "Sat, 19 Jun 2021 22:48:03 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Jan 2023 21:52:33 GMT",
"version": "v2"
}
] | 2023-01-23 | [
[
"Panotopoulos",
"Grigoris",
""
],
[
"Rubio",
"Javier",
""
],
[
"Lopes",
"Ilídio",
""
]
] | We study the impact of non-local modifications of General Relativity on stellar structure. In particular, assuming an analytic distortion function and specific equations of state, we made use of remnant stars to put qualitative constraints on a parameter not directly restricted by solar system tests. Using current data sets available for white dwarfs and strange quark stars candidates we find that the most stringent bounds come from the objects displaying the highest core densities, namely strange quark stars. Specifically, the constraints obtained from this class of stars are three to four orders of magnitude tighter than those obtained using white dwarfs. |
2401.15331 | Wang Zun | Zun Wang, Junjie Zhao, Zhoujian Cao | Accuracy of numerical relativity waveforms with respect to space-based
gravitational wave detectors | null | null | null | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | As with the laser interferometer gravitational-wave observatory (LIGO), the
matched filtering technique will be critical to the data analysis of
gravitational wave detection by space-based detectors, including LISA, Taiji
and Tianqin. Waveform templates are the basis for such matched filtering
techniques. To construct ready-to-use waveform templates, numerical relativity
waveforms are a starting point. Therefore, the accuracy issue of numerical
relativity waveforms is critically important. There are many investigations
regarding this issue with respect to LIGO. But unfortunately there are few
results on this issue with respect to space-based detectors. The current paper
investigates this problem. Our results indicate that the existing numerical
relativity waveforms are as accurate as 99% with respect to space-based
detectors, including LISA, Taiji and Tianqin. Such an accuracy level is
comparable to that with respect to LIGO.
| [
{
"created": "Sat, 27 Jan 2024 07:39:46 GMT",
"version": "v1"
}
] | 2024-01-30 | [
[
"Wang",
"Zun",
""
],
[
"Zhao",
"Junjie",
""
],
[
"Cao",
"Zhoujian",
""
]
] | As with the laser interferometer gravitational-wave observatory (LIGO), the matched filtering technique will be critical to the data analysis of gravitational wave detection by space-based detectors, including LISA, Taiji and Tianqin. Waveform templates are the basis for such matched filtering techniques. To construct ready-to-use waveform templates, numerical relativity waveforms are a starting point. Therefore, the accuracy issue of numerical relativity waveforms is critically important. There are many investigations regarding this issue with respect to LIGO. But unfortunately there are few results on this issue with respect to space-based detectors. The current paper investigates this problem. Our results indicate that the existing numerical relativity waveforms are as accurate as 99% with respect to space-based detectors, including LISA, Taiji and Tianqin. Such an accuracy level is comparable to that with respect to LIGO. |
1308.0318 | Lin-Qing Chen | Lin-Qing Chen | Orientability of loop processes in relative locality | 14 pages, 6 figures; v3 matches the published version | Phys. Rev. D 88, 124003 (2013) | 10.1103/PhysRevD.88.124003 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Inspired by recent results of unusual properties of loop processes in
relative locality, we introduce a way to classify loops in the case of
kappa-Poincare momentum space. We show that the notion of orientability is
deeply connected to a few essential properties of loop processes. Nonorientable
loops have "effective curvature", which explicitly breaks translation symmetry,
and can lead to a breaking of causality and global momentum conservation.
Orientable loops, on the other hand, are "flat." Causality and global momentum
conservation are all well preserved in this kind of loops. We comment that the
nontrivial classical loops in relative locality might be understood as dual
effects from general relativity, and some physical implications are discussed.
| [
{
"created": "Thu, 1 Aug 2013 19:50:02 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Aug 2013 05:34:12 GMT",
"version": "v2"
},
{
"created": "Tue, 3 Dec 2013 05:48:44 GMT",
"version": "v3"
}
] | 2013-12-16 | [
[
"Chen",
"Lin-Qing",
""
]
] | Inspired by recent results of unusual properties of loop processes in relative locality, we introduce a way to classify loops in the case of kappa-Poincare momentum space. We show that the notion of orientability is deeply connected to a few essential properties of loop processes. Nonorientable loops have "effective curvature", which explicitly breaks translation symmetry, and can lead to a breaking of causality and global momentum conservation. Orientable loops, on the other hand, are "flat." Causality and global momentum conservation are all well preserved in this kind of loops. We comment that the nontrivial classical loops in relative locality might be understood as dual effects from general relativity, and some physical implications are discussed. |
2003.07068 | Massimiliano Rinaldi | Alessandro Casalino, Aimeric Colleaux, Massimiliano Rinaldi, and
Silvia Vicentini | Regularized Lovelock gravity | Clarifications about the validity of the D->4 limiting procedure
added. References added | Physics of the Dark Universe, vol 31, 100770 (2021) | 10.1016/j.dark.2020.100770 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A four-dimensional regularization of Lovelock-Lanczos gravity up to an
arbitrary curvature order is considered. We show that Lovelock-Lanczos terms
can provide a non-trivial contribution to the Einstein field equations in four
dimensions, for spherically symmetric and
Friedmann-Lema\^{i}tre-Robertson-Walker spacetimes, as well as at first order
in perturbation theory around (anti) de Sitter vacua. We will discuss the
cosmological and black hole solutions arising from these theories, focusing on
the presence of attractors and their stability. Although curvature
singularities persist for any finite number of Lovelock terms, it is shown that
they disappear in the non-perturbative limit of a theory with a unique vacuum.
| [
{
"created": "Mon, 16 Mar 2020 08:16:45 GMT",
"version": "v1"
},
{
"created": "Sat, 21 Mar 2020 15:51:47 GMT",
"version": "v2"
},
{
"created": "Thu, 12 Nov 2020 11:20:51 GMT",
"version": "v3"
}
] | 2021-01-12 | [
[
"Casalino",
"Alessandro",
""
],
[
"Colleaux",
"Aimeric",
""
],
[
"Rinaldi",
"Massimiliano",
""
],
[
"Vicentini",
"Silvia",
""
]
] | A four-dimensional regularization of Lovelock-Lanczos gravity up to an arbitrary curvature order is considered. We show that Lovelock-Lanczos terms can provide a non-trivial contribution to the Einstein field equations in four dimensions, for spherically symmetric and Friedmann-Lema\^{i}tre-Robertson-Walker spacetimes, as well as at first order in perturbation theory around (anti) de Sitter vacua. We will discuss the cosmological and black hole solutions arising from these theories, focusing on the presence of attractors and their stability. Although curvature singularities persist for any finite number of Lovelock terms, it is shown that they disappear in the non-perturbative limit of a theory with a unique vacuum. |
gr-qc/9904029 | Carlo Rovelli | Carlo Rovelli | Spectral noncommutative geometry and quantization: a simple example | 7 pages, no figures | Phys.Rev.Lett. 83 (1999) 1079-1083 | 10.1103/PhysRevLett.83.1079 | null | gr-qc | null | We explore the relation between noncommutative geometry, in the spectral
triple formulation, and quantum mechanics. To this aim, we consider a dynamical
theory of a noncommutative geometry defined by a spectral triple, and study its
quantization. In particular, we consider a simple model based on a finite
dimensional spectral triple (A, H, D), which mimics certain aspects of the
spectral formulation of general relativity. We find the physical phase space,
which is the space of the onshell Dirac operators compatible with A and H. We
define a natural symplectic structure over this phase space and construct the
corresponding quantum theory using a covariant canonical quantization approach.
We show that the Connes distance between certain two states over the algebra A
(two ``spacetime points''), which is an arbitrary positive number in the
classical noncommutative geometry, turns out to be discrete in the quantum
theory, and we compute its spectrum. The quantum states of the noncommutative
geometry form a Hilbert space K. D is promoted to an operator *D on the direct
product *H of H and K. The triple (A, *H, *D) can be viewed as the quantization
of the family of the triples (A, H, D).
| [
{
"created": "Tue, 13 Apr 1999 09:08:21 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Rovelli",
"Carlo",
""
]
] | We explore the relation between noncommutative geometry, in the spectral triple formulation, and quantum mechanics. To this aim, we consider a dynamical theory of a noncommutative geometry defined by a spectral triple, and study its quantization. In particular, we consider a simple model based on a finite dimensional spectral triple (A, H, D), which mimics certain aspects of the spectral formulation of general relativity. We find the physical phase space, which is the space of the onshell Dirac operators compatible with A and H. We define a natural symplectic structure over this phase space and construct the corresponding quantum theory using a covariant canonical quantization approach. We show that the Connes distance between certain two states over the algebra A (two ``spacetime points''), which is an arbitrary positive number in the classical noncommutative geometry, turns out to be discrete in the quantum theory, and we compute its spectrum. The quantum states of the noncommutative geometry form a Hilbert space K. D is promoted to an operator *D on the direct product *H of H and K. The triple (A, *H, *D) can be viewed as the quantization of the family of the triples (A, H, D). |
0705.1359 | David Brown | J. David Brown | Puncture Evolution of Schwarzschild Black Holes | This is the final version to be published in PRD. One important
change: the phrase "excision by under resolution" is replaced by the more
appropriate phrase "natural excision" | Phys.Rev.D77:044018,2008 | 10.1103/PhysRevD.77.044018 | null | gr-qc | null | The moving puncture method is analyzed for a single, non-spinning black hole.
It is shown that the puncture region is not resolved by current numerical
codes. As a result, the geometry near the puncture appears to evolve to an
infinitely long cylinder of finite areal radius. The puncture itself actually
remains at spacelike infinity throughout the evolution. In the limit of
infinite resolution the data never become stationary. However, at any
reasonable finite resolution the grid points closest to the puncture are
rapidly drawn into the black hole interior by the Gamma-driver shift condition.
The data can then evolve to a stationary state. These results suggest that the
moving puncture technique should be viewed as a type of "natural excision".
| [
{
"created": "Wed, 9 May 2007 20:19:00 GMT",
"version": "v1"
},
{
"created": "Fri, 25 May 2007 20:06:07 GMT",
"version": "v2"
},
{
"created": "Tue, 15 Jan 2008 15:04:24 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Brown",
"J. David",
""
]
] | The moving puncture method is analyzed for a single, non-spinning black hole. It is shown that the puncture region is not resolved by current numerical codes. As a result, the geometry near the puncture appears to evolve to an infinitely long cylinder of finite areal radius. The puncture itself actually remains at spacelike infinity throughout the evolution. In the limit of infinite resolution the data never become stationary. However, at any reasonable finite resolution the grid points closest to the puncture are rapidly drawn into the black hole interior by the Gamma-driver shift condition. The data can then evolve to a stationary state. These results suggest that the moving puncture technique should be viewed as a type of "natural excision". |
2206.05110 | Simran Arora | Simran Arora, P.K. Sahoo | Crossing phantom divide in $f(Q)$ gravity | Annalen der Physik accepted version | Annalen der Physik, 534 (2022) 2200233 | 10.1002/andp.202200233 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We investigate the possibility of crossing a phantom divide line in the
extension of symmetric teleparallel gravity or the $f(Q)$ gravity, where $Q$ is
the non-metricity. We study the cosmic evolution of the effective equation of
state parameter for dark energy considering exponential, logarithmic, and
combined $f(Q)$ theories. Moreover, the exponential model behaves like the
$\Lambda$CDM at high redshifts before deviating to $\omega_{eff}<-1$ or
$\omega_{eff}>-1$, respectively, depending on the value of model parameter. It
also approaches a de-sitter phase asymptotically. However, the crossing of the
phantom divide line, i.e., $\omega= -1$, is realized in the combined $f(Q)$
theory. Furthermore, statefinder diagnostics are studied in order to
differentiate between several dark energy models. To ensure the three model's
stability, we employ the stability analysis using linear perturbations. We
demonstrate how to reassemble $f(Q)$ via a numerical inversion approach based
on existing observational constraints on cosmographic parameters and the
potential of bridging the phantom divide in the resulting model. It explicitly
demonstrates that future crossings of the phantom dividing line are a generic
feature of feasible $f(Q)$ gravity models.
| [
{
"created": "Wed, 8 Jun 2022 16:05:36 GMT",
"version": "v1"
}
] | 2022-08-10 | [
[
"Arora",
"Simran",
""
],
[
"Sahoo",
"P. K.",
""
]
] | We investigate the possibility of crossing a phantom divide line in the extension of symmetric teleparallel gravity or the $f(Q)$ gravity, where $Q$ is the non-metricity. We study the cosmic evolution of the effective equation of state parameter for dark energy considering exponential, logarithmic, and combined $f(Q)$ theories. Moreover, the exponential model behaves like the $\Lambda$CDM at high redshifts before deviating to $\omega_{eff}<-1$ or $\omega_{eff}>-1$, respectively, depending on the value of model parameter. It also approaches a de-sitter phase asymptotically. However, the crossing of the phantom divide line, i.e., $\omega= -1$, is realized in the combined $f(Q)$ theory. Furthermore, statefinder diagnostics are studied in order to differentiate between several dark energy models. To ensure the three model's stability, we employ the stability analysis using linear perturbations. We demonstrate how to reassemble $f(Q)$ via a numerical inversion approach based on existing observational constraints on cosmographic parameters and the potential of bridging the phantom divide in the resulting model. It explicitly demonstrates that future crossings of the phantom dividing line are a generic feature of feasible $f(Q)$ gravity models. |
1005.0717 | Roberto A. Sussman | Roberto A. Sussman | Evolution of radial profiles in regular Lemaitre-Tolman-Bondi dust
models | Final version to appear in Classical and Quantum Gravity. Readers
eager to know the results and implications without having to go through the
technical detail are recommended to go directly to the summary and discussion
in the final section (section 11). Typos have been corrected and an important
reference has been added | Class.Quant.Grav.27:175001,2010 | 10.1088/0264-9381/27/17/175001 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We undertake a comprehensive and rigorous analytic study of the evolution of
radial profiles of covariant scalars in regular Lemaitre-Tolman-Bondi dust
models. We consider specifically the phenomenon of "profile inversions" in
which an initial clump profile of density, spatial curvature or the expansion
scalar, might evolve into a void profile (and vice versa). Previous work in the
literature on models with density void profiles and/or allowing for density
profile inversions is given full generalization, with some erroneous results
corrected. We prove rigorously that if an evolution without shell crossings is
assumed, then only the 'clump to void' inversion can occur in density profiles,
and only in hyperbolic models or regions with negative spatial curvature. The
profiles of spatial curvature follow similar patterns as those of the density,
with 'clump to void' inversions only possible for hyperbolic models or regions.
However, profiles of the expansion scalar are less restrictive, with profile
inversions necessarily taking place in elliptic models. We also examine radial
profiles in special LTB configurations: closed elliptic models, models with a
simultaneous big bang singularity, as well as a locally collapsing elliptic
region surrounded by an expanding hyperbolic background. The general analytic
statements that we obtain allow for setting up the right initial conditions to
construct fully regular LTB models with any specific qualitative requirements
for the profiles of all scalars and their time evolution. The results presented
can be very useful in guiding future numerical work on these models and in
revising previous analytic work on all their applications.
| [
{
"created": "Wed, 5 May 2010 10:42:20 GMT",
"version": "v1"
},
{
"created": "Tue, 11 May 2010 08:19:44 GMT",
"version": "v2"
},
{
"created": "Wed, 9 Jun 2010 05:51:50 GMT",
"version": "v3"
}
] | 2015-03-17 | [
[
"Sussman",
"Roberto A.",
""
]
] | We undertake a comprehensive and rigorous analytic study of the evolution of radial profiles of covariant scalars in regular Lemaitre-Tolman-Bondi dust models. We consider specifically the phenomenon of "profile inversions" in which an initial clump profile of density, spatial curvature or the expansion scalar, might evolve into a void profile (and vice versa). Previous work in the literature on models with density void profiles and/or allowing for density profile inversions is given full generalization, with some erroneous results corrected. We prove rigorously that if an evolution without shell crossings is assumed, then only the 'clump to void' inversion can occur in density profiles, and only in hyperbolic models or regions with negative spatial curvature. The profiles of spatial curvature follow similar patterns as those of the density, with 'clump to void' inversions only possible for hyperbolic models or regions. However, profiles of the expansion scalar are less restrictive, with profile inversions necessarily taking place in elliptic models. We also examine radial profiles in special LTB configurations: closed elliptic models, models with a simultaneous big bang singularity, as well as a locally collapsing elliptic region surrounded by an expanding hyperbolic background. The general analytic statements that we obtain allow for setting up the right initial conditions to construct fully regular LTB models with any specific qualitative requirements for the profiles of all scalars and their time evolution. The results presented can be very useful in guiding future numerical work on these models and in revising previous analytic work on all their applications. |
2201.05036 | Avik De Dr. | Avik De, Sanjay Mandal, J.T. Beh, Tee-How Loo and P.K. Sahoo | Isotropization of locally rotationally symmetric Bianchi-I universe in
$f(Q)$-gravity | Accepted on 12/01/2022 for publication in the journal EPJC | Eur. Phys. J. C 82, 72 (2022) | 10.1140/epjc/s10052-022-10021-9 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Despite having the somewhat successful description of accelerated cosmology,
the early evolution of the universe always challenges mankind. Our promising
approach lies in a new class of symmetric teleparallel theory of gravity named
$f(Q)$, where the non-metricity scalar $Q$ is responsible for the gravitational
interaction, which may resolve some of the issues. To study the early evolution
of the universe, we presume an anisotropic locally rotationally symmetric (LRS)
Bianchi-I spacetime and derive the motion equations. We discuss the profiles of
energy density, equation of state and skewness parameter and observe that our
models archive anisotropic spatial geometry in the early phase of the universe
with a possible presence of anisotropic fluid and as time goes on, even in the
presence of an anisotropic fluid, the universe could approach isotropy due to
inflation and the anisotropy of the fluid fades away at the same time.
| [
{
"created": "Wed, 12 Jan 2022 02:10:07 GMT",
"version": "v1"
}
] | 2022-01-25 | [
[
"De",
"Avik",
""
],
[
"Mandal",
"Sanjay",
""
],
[
"Beh",
"J. T.",
""
],
[
"Loo",
"Tee-How",
""
],
[
"Sahoo",
"P. K.",
""
]
] | Despite having the somewhat successful description of accelerated cosmology, the early evolution of the universe always challenges mankind. Our promising approach lies in a new class of symmetric teleparallel theory of gravity named $f(Q)$, where the non-metricity scalar $Q$ is responsible for the gravitational interaction, which may resolve some of the issues. To study the early evolution of the universe, we presume an anisotropic locally rotationally symmetric (LRS) Bianchi-I spacetime and derive the motion equations. We discuss the profiles of energy density, equation of state and skewness parameter and observe that our models archive anisotropic spatial geometry in the early phase of the universe with a possible presence of anisotropic fluid and as time goes on, even in the presence of an anisotropic fluid, the universe could approach isotropy due to inflation and the anisotropy of the fluid fades away at the same time. |
1101.1147 | Kouji Nakamura | Kouji Nakamura | Decomposition of linear metric perturbations on generic background
spacetime -- Toward higher-order general-relativistic gauge-invariant
perturbation theory | 41 pages, no figure, Full paper version of [arXiv:1011.5272[gr-qc]] | null | null | null | gr-qc astro-ph.CO hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The decomposition of the linear-order metric perturbation is discussed in the
context of the higher-order gauge-invariant perturbation theory. We show that
the linear order metric perturbation is decomposed into gauge-invariant and
gauge-variant parts on the general background spacetime which admits ADM
decomposition. This decomposition was an important premise of the general
framework of the higher order gauge-invariant perturbation theory proposed in
the papers [K. Nakamura, Prog. Theor. Phys. vol.110 (2003), 723; ibid. vol.113
(2005), 481]. This implies that we can develop the higher-order gauge-invariant
perturbation theory on generic background spacetime. Remaining issues to
complete the general-framework of the higher-order gauge-invariant perturbation
theories are also discussed.
| [
{
"created": "Thu, 6 Jan 2011 06:40:19 GMT",
"version": "v1"
}
] | 2011-01-10 | [
[
"Nakamura",
"Kouji",
""
]
] | The decomposition of the linear-order metric perturbation is discussed in the context of the higher-order gauge-invariant perturbation theory. We show that the linear order metric perturbation is decomposed into gauge-invariant and gauge-variant parts on the general background spacetime which admits ADM decomposition. This decomposition was an important premise of the general framework of the higher order gauge-invariant perturbation theory proposed in the papers [K. Nakamura, Prog. Theor. Phys. vol.110 (2003), 723; ibid. vol.113 (2005), 481]. This implies that we can develop the higher-order gauge-invariant perturbation theory on generic background spacetime. Remaining issues to complete the general-framework of the higher-order gauge-invariant perturbation theories are also discussed. |
1802.00098 | Kirill Bronnikov | Kirill A. Bronnikov | Scalar fields as sources for wormholes and regular black holes | 29 pages, 6 figures. Some comments and 6 references added | Particles 2018, 1, 5 | 10.3390/particles1010005 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review nonsingular static, spherically symmetric solutions of general
relativity with a minimally coupled scalar field $\phi$ as a source. Considered
are wormholes and regular black holes without a center, including black
universes (black holes with an expanding cosmology beyond the horizon). Such
configurations require a "ghost" field with negative kinetic energy, but it may
be negative in a restricted (strong-field) region of space and positive outside
it ("trapped ghost") thus explaining why no ghosts are observed under usual
conditions. Another possible explanation of the same may be a rapid decay of a
ghost field at large radii. Before discussing particular examples, some general
results are presented, such as the necessity of anisotropic matter for
obtaining asymptotically flat or anti-de Sitter wormholes, no-hair and global
structure theorems for black holes with scalar fields. The stability properties
of scalar wormholes and regular black holes are discussed for perturbations
preserving spherical symmetry. It is stressed that the effective potential
$V_{eff}$ for perturbations has universal shapes near generic wormhole throats
(a positive pole regularizable by a Darboux transformation) and near transition
surfaces from canonical to ghost behavior of the scalar field (a negative pole
at which the perturbation finiteness requirement plays a stabilizing role). It
is also found that positive poles of $V_{eff}$ emerging at "long throats" (with
the spherical radius $r \approx r_0 + {\rm const} \cdot x^{2n}$, $n > 1$, if
$x=0$ is the throat) may be regularized by repeated Darboux transformations for
some values of $n$.
| [
{
"created": "Wed, 31 Jan 2018 23:27:09 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Mar 2018 05:46:02 GMT",
"version": "v2"
}
] | 2018-03-16 | [
[
"Bronnikov",
"Kirill A.",
""
]
] | We review nonsingular static, spherically symmetric solutions of general relativity with a minimally coupled scalar field $\phi$ as a source. Considered are wormholes and regular black holes without a center, including black universes (black holes with an expanding cosmology beyond the horizon). Such configurations require a "ghost" field with negative kinetic energy, but it may be negative in a restricted (strong-field) region of space and positive outside it ("trapped ghost") thus explaining why no ghosts are observed under usual conditions. Another possible explanation of the same may be a rapid decay of a ghost field at large radii. Before discussing particular examples, some general results are presented, such as the necessity of anisotropic matter for obtaining asymptotically flat or anti-de Sitter wormholes, no-hair and global structure theorems for black holes with scalar fields. The stability properties of scalar wormholes and regular black holes are discussed for perturbations preserving spherical symmetry. It is stressed that the effective potential $V_{eff}$ for perturbations has universal shapes near generic wormhole throats (a positive pole regularizable by a Darboux transformation) and near transition surfaces from canonical to ghost behavior of the scalar field (a negative pole at which the perturbation finiteness requirement plays a stabilizing role). It is also found that positive poles of $V_{eff}$ emerging at "long throats" (with the spherical radius $r \approx r_0 + {\rm const} \cdot x^{2n}$, $n > 1$, if $x=0$ is the throat) may be regularized by repeated Darboux transformations for some values of $n$. |
1409.6656 | Steven Willison | Steven Willison | Local Well-posedness of Lovelock gravity | 2 pages, no figures. This article agrees with the published version
apart from small corrections in equation 2 and text below equations 2 and 7 | Class. Quant. Grav. 32 022001 (2015) | 10.1088/0264-9381/32/2/022001 | null | gr-qc hep-th math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has long been known that Lovelock gravity, being of Cauchy-Kowalevskaya
type, admits a well defined initial value problem for analytic data. However,
this does not address the physically important issues of continuous dependence
of the solution on the data and the domain of dependence property. In this note
we fill this gap in our understanding of the (local) dynamics of the theory. We
show that, by a known mathematical trick, the fully nonlinear
harmonic-gauge-reduced Lovelock field equations can be made equivalent to a
quasilinear PDE system. Due to this equivalence, an analysis of the principal
symbol, as has appeared in recent works by other authors, is sufficient to
decide the issue of local well-posedness of perturbations about a given
background.
| [
{
"created": "Tue, 23 Sep 2014 16:18:36 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Jan 2015 11:35:03 GMT",
"version": "v2"
}
] | 2015-06-23 | [
[
"Willison",
"Steven",
""
]
] | It has long been known that Lovelock gravity, being of Cauchy-Kowalevskaya type, admits a well defined initial value problem for analytic data. However, this does not address the physically important issues of continuous dependence of the solution on the data and the domain of dependence property. In this note we fill this gap in our understanding of the (local) dynamics of the theory. We show that, by a known mathematical trick, the fully nonlinear harmonic-gauge-reduced Lovelock field equations can be made equivalent to a quasilinear PDE system. Due to this equivalence, an analysis of the principal symbol, as has appeared in recent works by other authors, is sufficient to decide the issue of local well-posedness of perturbations about a given background. |
2110.13836 | Shouvik Sadhukhan Mr | Alokananda Kar, Shouvik Sadhukhan, Surajit Chattopadhyay | Thermodynamics and energy condition analysis for Van-Der-Waals EOS
without viscous cosmology | 28 pages, 27 figures. Physica Scripta (2021) | null | 10.1088/1402-4896/ac2f00 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In this paper we have studied Van-Der-Waals fluid system with the generalized
EOS as as discussed in the recent works of Kremer, G.M [1, 4], Vardiashvili, G
[2], Jantsch, R.C [3], Capozziello, S [5]. and are functions of energy density
and time that are different for the three types of Van der Waals fluid which
are one parameter model, two parameters model and three parameters model. We
have studied the changes in the parameters for different cosmic phases. We have
also investigated the thermodynamics and the stability conditions for these
three models. Finally, we have resolved the finite time future singularity
problems
| [
{
"created": "Tue, 26 Oct 2021 16:32:57 GMT",
"version": "v1"
}
] | 2021-10-27 | [
[
"Kar",
"Alokananda",
""
],
[
"Sadhukhan",
"Shouvik",
""
],
[
"Chattopadhyay",
"Surajit",
""
]
] | In this paper we have studied Van-Der-Waals fluid system with the generalized EOS as as discussed in the recent works of Kremer, G.M [1, 4], Vardiashvili, G [2], Jantsch, R.C [3], Capozziello, S [5]. and are functions of energy density and time that are different for the three types of Van der Waals fluid which are one parameter model, two parameters model and three parameters model. We have studied the changes in the parameters for different cosmic phases. We have also investigated the thermodynamics and the stability conditions for these three models. Finally, we have resolved the finite time future singularity problems |
1201.2805 | Cecilia Chirenti | Cecilia Chirenti and Alberto Saa | Double null formulation of the general Vaidya metric | 13 pages, 5 figures, final version to appear in CQG | Class. Quantum Grav. 29, 135003 (2012) | 10.1088/0264-9381/29/13/135003 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present here the field equations describing a non-stationary spherically
symmetric n-dimensional charged black hole with varying mass m(v) and/or
electric charge q(v), described by a generic charged Vaidya metric with
cosmological constant Lambda in double null coordinates. This formulation of
the metric has been shown to be particularly useful for perturbative studies
and it was used in some recent works. Here we also discuss some issues related
to the apparent and event horizons of the black hole.
| [
{
"created": "Fri, 13 Jan 2012 11:17:34 GMT",
"version": "v1"
},
{
"created": "Thu, 3 May 2012 15:04:22 GMT",
"version": "v2"
}
] | 2012-05-30 | [
[
"Chirenti",
"Cecilia",
""
],
[
"Saa",
"Alberto",
""
]
] | We present here the field equations describing a non-stationary spherically symmetric n-dimensional charged black hole with varying mass m(v) and/or electric charge q(v), described by a generic charged Vaidya metric with cosmological constant Lambda in double null coordinates. This formulation of the metric has been shown to be particularly useful for perturbative studies and it was used in some recent works. Here we also discuss some issues related to the apparent and event horizons of the black hole. |
gr-qc/9506083 | Matt Visser | Eric Poisson and Matt Visser (Washington University) | Thin-shell wormholes: Linearization stability | 4 pages; ReV_TeX 3.0; one postscript figure | Phys.Rev. D52 (1995) 7318-7321 | 10.1103/PhysRevD.52.7318 | null | gr-qc | null | The class of spherically-symmetric thin-shell wormholes provides a
particularly elegant collection of exemplars for the study of traversable
Lorentzian wormholes. In the present paper we consider linearized (spherically
symmetric) perturbations around some assumed static solution of the Einstein
field equations. This permits us to relate stability issues to the (linearized)
equation of state of the exotic matter which is located at the wormhole throat.
| [
{
"created": "Fri, 30 Jun 1995 18:49:41 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Poisson",
"Eric",
"",
"Washington University"
],
[
"Visser",
"Matt",
"",
"Washington University"
]
] | The class of spherically-symmetric thin-shell wormholes provides a particularly elegant collection of exemplars for the study of traversable Lorentzian wormholes. In the present paper we consider linearized (spherically symmetric) perturbations around some assumed static solution of the Einstein field equations. This permits us to relate stability issues to the (linearized) equation of state of the exotic matter which is located at the wormhole throat. |
gr-qc/0605075 | Malcolm MacCallum | Mar\'ia Jes\'us Pareja and Malcolm A.H. MacCallum | Local freedom in the gravitational field revisited | LaTeX. 13 pp. To be submitted to Class. Quant. Grav | Class.Quant.Grav. 23 (2006) 5039-5048 | 10.1088/0264-9381/23/15/019 | null | gr-qc | null | Maartens {\it et al.}\@ gave a covariant characterization, in a 1+3 formalism
based on a perfect fluid's velocity, of the parts of the first derivatives of
the curvature tensor in general relativity which are ``locally free'', i.e. not
pointwise determined by the fluid energy momentum and its derivative. The full
decomposition of independent curvature derivative components given in earlier
work on the spinor approach to the equivalence problem enables analogous
general results to be stated for any order: the independent matter terms can
also be characterized. Explicit relations between the two sets of results are
obtained. The 24 Maartens {\it et al.} locally free data are shown to
correspond to the $\nabla \Psi$ quantities in the spinor approach, and the
fluid terms are similarly related to the remaining 16 independent quantities in
the first derivatives of the curvature.
| [
{
"created": "Fri, 12 May 2006 12:21:32 GMT",
"version": "v1"
}
] | 2016-08-16 | [
[
"Pareja",
"María Jesús",
""
],
[
"MacCallum",
"Malcolm A. H.",
""
]
] | Maartens {\it et al.}\@ gave a covariant characterization, in a 1+3 formalism based on a perfect fluid's velocity, of the parts of the first derivatives of the curvature tensor in general relativity which are ``locally free'', i.e. not pointwise determined by the fluid energy momentum and its derivative. The full decomposition of independent curvature derivative components given in earlier work on the spinor approach to the equivalence problem enables analogous general results to be stated for any order: the independent matter terms can also be characterized. Explicit relations between the two sets of results are obtained. The 24 Maartens {\it et al.} locally free data are shown to correspond to the $\nabla \Psi$ quantities in the spinor approach, and the fluid terms are similarly related to the remaining 16 independent quantities in the first derivatives of the curvature. |
1901.06400 | Eduardo Rodr\'iguez | Fernando Izaurieta, Eduardo Rodr\'iguez, Omar Valdivia | Linear and Second-order Geometry Perturbations on Spacetimes with
Torsion | 6 pages, no figures. v2: version accepted for publication in EPJC | null | 10.1140/epjc/s10052-019-6852-y | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In order to study gravitational waves in any realistic astrophysical
scenario, one must consider geometry perturbations up to second order. Here, we
present a general technique for studying linear and quadratic perturbations on
a spacetime with torsion. Besides the standard metric mode, a "torsionon"
perturbation mode appears. This torsional mode will be able to propagate only
in a certain kind of theories.
| [
{
"created": "Fri, 18 Jan 2019 19:36:02 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Apr 2019 21:04:24 GMT",
"version": "v2"
}
] | 2019-05-01 | [
[
"Izaurieta",
"Fernando",
""
],
[
"Rodríguez",
"Eduardo",
""
],
[
"Valdivia",
"Omar",
""
]
] | In order to study gravitational waves in any realistic astrophysical scenario, one must consider geometry perturbations up to second order. Here, we present a general technique for studying linear and quadratic perturbations on a spacetime with torsion. Besides the standard metric mode, a "torsionon" perturbation mode appears. This torsional mode will be able to propagate only in a certain kind of theories. |
0807.4483 | John Veitch | John Veitch, Alberto Vecchio | Assigning confidence to inspiral gravitational wave candidates with
Bayesian model selection | From the Proceedings of the 11th Gravitational Wave Data Analysis
Workshop 11 pages, 4 pages | Class. Quantum Grav. 25 (2008) 184010 | 10.1088/0264-9381/25/18/184010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Bayesian model selection provides a powerful and mathematically transparent
framework to tackle hypothesis testing, such as detection tests of
gravitational waves emitted during the coalescence of binary systems using
ground-based laser interferometers. Although its implementation is
computationally intensive, we have developed an efficient probabilistic
algorithm based on a technique known as nested sampling that makes Bayesian
model selection applicable to follow-up studies of candidate signals produced
by on-going searches of inspiralling compact binaries. We discuss the
performance of this approach, in terms of "false alarm rate" and "detection
probability" of restricted second post-Newtonian inspiral waveforms from
non-spinning compact objects in binary systems. The results confirm that this
approach is a viable tool for detection tests in current searches for
gravitational wave signals.
| [
{
"created": "Mon, 28 Jul 2008 16:08:15 GMT",
"version": "v1"
}
] | 2009-11-13 | [
[
"Veitch",
"John",
""
],
[
"Vecchio",
"Alberto",
""
]
] | Bayesian model selection provides a powerful and mathematically transparent framework to tackle hypothesis testing, such as detection tests of gravitational waves emitted during the coalescence of binary systems using ground-based laser interferometers. Although its implementation is computationally intensive, we have developed an efficient probabilistic algorithm based on a technique known as nested sampling that makes Bayesian model selection applicable to follow-up studies of candidate signals produced by on-going searches of inspiralling compact binaries. We discuss the performance of this approach, in terms of "false alarm rate" and "detection probability" of restricted second post-Newtonian inspiral waveforms from non-spinning compact objects in binary systems. The results confirm that this approach is a viable tool for detection tests in current searches for gravitational wave signals. |
2108.04056 | Ettore Minguzzi | Sebastian Gurriaran and Ettore Minguzzi | Surface gravity of compact non-degenerate horizons under the dominant
energy condition | Latex, 37 pages, 2 figures. v2: added appendix and one figure,
expanded introduction | Commun. Math. Phys. 395 (2022) 679-713 | 10.1007/s00220-022-04440-8 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove that under the dominant energy condition any non-degenerate smooth
compact totally geodesic horizon admits a smooth tangent vector field of
constant non-zero surface gravity. This result generalizes previous work by
Isenberg and Moncrief, and by Bustamante and Reiris to the non-vacuum case, the
vacuum case being given a largely independent proof. Moreover, we prove that
any such achronal non-degenerate horizon is actually a Cauchy horizon bounded
on one side by a chronology violating region.
| [
{
"created": "Mon, 9 Aug 2021 14:10:29 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Jun 2022 08:13:53 GMT",
"version": "v2"
}
] | 2022-09-27 | [
[
"Gurriaran",
"Sebastian",
""
],
[
"Minguzzi",
"Ettore",
""
]
] | We prove that under the dominant energy condition any non-degenerate smooth compact totally geodesic horizon admits a smooth tangent vector field of constant non-zero surface gravity. This result generalizes previous work by Isenberg and Moncrief, and by Bustamante and Reiris to the non-vacuum case, the vacuum case being given a largely independent proof. Moreover, we prove that any such achronal non-degenerate horizon is actually a Cauchy horizon bounded on one side by a chronology violating region. |
0712.0465 | Valentin Kuzmichev | V. E. Kuzmichev, V. V. Kuzmichev (Bogolyubov Institute for Theoretical
Physics) | Accelerating Quantum Universe | 15 pages, v.2 additional explanations and a few corrections are
provided | Acta Phys.Polon.B39:2003-2018,2008 | null | null | gr-qc astro-ph | null | The origin of negative pressure fluid (the dark energy) is investigated in
the quantum model of the homogeneous, isotropic and closed universe filled with
a uniform scalar field and a perfect fluid which defines a reference frame. The
equations of the model are reduced to the form which allows a direct comparison
between them and the equations of the Einsteinian classical theory of gravity.
It is shown that quantized scalar field has a form of a condensate which
behaves as an antigravitating medium. The theory predicts an accelerating
expansion of the universe even if the vacuum energy density vanishes. An
antigravitating effect of a condensate has a purely quantum nature. It is shown
that the universe with the parameters close to the Planck ones can go through
the period of exponential expansion. The conditions under which in
semi-classical approximation the universe looks effectively like spatially flat
with negative deceleration parameter are determined. The reduction to the
standard model of classical cosmology is discussed.
| [
{
"created": "Tue, 4 Dec 2007 09:46:01 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Apr 2008 09:09:27 GMT",
"version": "v2"
}
] | 2008-12-19 | [
[
"Kuzmichev",
"V. E.",
"",
"Bogolyubov Institute for Theoretical\n Physics"
],
[
"Kuzmichev",
"V. V.",
"",
"Bogolyubov Institute for Theoretical\n Physics"
]
] | The origin of negative pressure fluid (the dark energy) is investigated in the quantum model of the homogeneous, isotropic and closed universe filled with a uniform scalar field and a perfect fluid which defines a reference frame. The equations of the model are reduced to the form which allows a direct comparison between them and the equations of the Einsteinian classical theory of gravity. It is shown that quantized scalar field has a form of a condensate which behaves as an antigravitating medium. The theory predicts an accelerating expansion of the universe even if the vacuum energy density vanishes. An antigravitating effect of a condensate has a purely quantum nature. It is shown that the universe with the parameters close to the Planck ones can go through the period of exponential expansion. The conditions under which in semi-classical approximation the universe looks effectively like spatially flat with negative deceleration parameter are determined. The reduction to the standard model of classical cosmology is discussed. |
2308.08281 | Bahram Mashhoon | Javad Tabatabaei, Abdolali Banihashemi, Shant Baghram, and Bahram
Mashhoon | Anisotropic Cosmology in the Local Limit of Nonlocal Gravity | 25 pages; v2: minor improvements, invited contribution to appear in
Universe | Universe 9, 377 (2023) | 10.3390/universe9090377 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | Within the framework of the local limit of nonlocal gravity (NLG), we
investigate a class of Bianchi type I spatially homogeneous but anisotropic
cosmological models. The modified field equations are presented in this case
and some special solutions are discussed in detail. This modified gravity
theory contains a susceptibility function S(x) such that general relativity
(GR) is recovered for S = 0. In the modified anisotropic cosmological models,
we explore the contribution of S(t) and its temporal derivative to the local
anisotropic cosmic acceleration. The implications of our results for
observational cosmology are briefly discussed.
| [
{
"created": "Wed, 16 Aug 2023 10:42:08 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Aug 2023 08:41:56 GMT",
"version": "v2"
}
] | 2023-08-24 | [
[
"Tabatabaei",
"Javad",
""
],
[
"Banihashemi",
"Abdolali",
""
],
[
"Baghram",
"Shant",
""
],
[
"Mashhoon",
"Bahram",
""
]
] | Within the framework of the local limit of nonlocal gravity (NLG), we investigate a class of Bianchi type I spatially homogeneous but anisotropic cosmological models. The modified field equations are presented in this case and some special solutions are discussed in detail. This modified gravity theory contains a susceptibility function S(x) such that general relativity (GR) is recovered for S = 0. In the modified anisotropic cosmological models, we explore the contribution of S(t) and its temporal derivative to the local anisotropic cosmic acceleration. The implications of our results for observational cosmology are briefly discussed. |
gr-qc/0009050 | Stefano Liberati | S. Liberati | Vacuum Effects in Gravitational Fields: Theory and Detectability | Latex2e, 237 pages, 36 figures. Ph.D. Thesis | null | null | null | gr-qc | null | In this thesis, we investigate quantum vacuum effects in the presence of
gravitational fields. After discussing the general theory of vacuum effects in
strong fields we apply it to the relevant issue of the interaction of the
quantum vacuum with black hole geometries. In particular we consider the
long-standing problem of the interpretation of gravitational entropy. After
these investigations, we discuss the possible experimental tests of particle
creation from the quantum vacuum. This leads us to study acoustic geometries
and their way of ``simulating'' gravitational structures, such as horizons and
black holes. We study the stability of these structures and the problems
related to setting up experimental detection of ``phonon Hawking flux'' from
acoustic horizons. This line of research then leads us to propose a new model
for explaining the emission of light in the phenomenon of Sonoluminescence,
based on the dynamical Casimir effect. This is possibly amenable to
experimental investigation. Finally we consider high energy phenomena in the
early universe. In particular we discuss inflation and possible alternative
frameworks for solving the cosmological puzzles.
| [
{
"created": "Thu, 14 Sep 2000 15:07:51 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Liberati",
"S.",
""
]
] | In this thesis, we investigate quantum vacuum effects in the presence of gravitational fields. After discussing the general theory of vacuum effects in strong fields we apply it to the relevant issue of the interaction of the quantum vacuum with black hole geometries. In particular we consider the long-standing problem of the interpretation of gravitational entropy. After these investigations, we discuss the possible experimental tests of particle creation from the quantum vacuum. This leads us to study acoustic geometries and their way of ``simulating'' gravitational structures, such as horizons and black holes. We study the stability of these structures and the problems related to setting up experimental detection of ``phonon Hawking flux'' from acoustic horizons. This line of research then leads us to propose a new model for explaining the emission of light in the phenomenon of Sonoluminescence, based on the dynamical Casimir effect. This is possibly amenable to experimental investigation. Finally we consider high energy phenomena in the early universe. In particular we discuss inflation and possible alternative frameworks for solving the cosmological puzzles. |
1812.03844 | Luigi Pilo | Sabino Matarrese, Luigi Pilo, Rocco Rollo | $\Delta N$ Formalism and Conserved Currents in Cosmology | 19 pages, 1 figures. Final version accepted for publication in JCAP.
Title slightly changed to avoid confusion with existing literature. Expanded
content with the same conclusions | null | 10.1088/1475-7516/2019/04/017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The $\Delta N$ formalism, based on the counting of the number of e-folds
during inflation in different local patches of the Universe, has been
introduced several years ago as a simple and physically intuitive approach to
calculate (non-linear) curvature perturbations from inflation on large sales,
without resorting to the full machinery of (higher-order) perturbation theory.
Later on, it was claimed the equivalence with the results found by introducing
a conserved fully non-linear current $\zeta_\mu$, thereby allowing to directly
connect perturbations during inflation to late-Universe observables. We discus
some issues arising from the choice of the initial hyper-surface in the $\Delta
N$ formalism. By using a novel exact expression for $\zeta_\mu$, valid for any
barotropic fluid, we find that it is not in general related to the standard
uniform density curvature perturbation $\zeta$; such a result conflicts with
the claimed equivalence with $\Delta N$ formalism. Moreover, a similar analysis
is done for the proposed non-perturbative generalization ${\cal R}_\mu$ of the
comoving curvature perturbation ${\cal R}$.
| [
{
"created": "Thu, 6 Dec 2018 17:48:47 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Dec 2018 11:29:07 GMT",
"version": "v2"
},
{
"created": "Mon, 1 Apr 2019 07:51:53 GMT",
"version": "v3"
}
] | 2019-04-17 | [
[
"Matarrese",
"Sabino",
""
],
[
"Pilo",
"Luigi",
""
],
[
"Rollo",
"Rocco",
""
]
] | The $\Delta N$ formalism, based on the counting of the number of e-folds during inflation in different local patches of the Universe, has been introduced several years ago as a simple and physically intuitive approach to calculate (non-linear) curvature perturbations from inflation on large sales, without resorting to the full machinery of (higher-order) perturbation theory. Later on, it was claimed the equivalence with the results found by introducing a conserved fully non-linear current $\zeta_\mu$, thereby allowing to directly connect perturbations during inflation to late-Universe observables. We discus some issues arising from the choice of the initial hyper-surface in the $\Delta N$ formalism. By using a novel exact expression for $\zeta_\mu$, valid for any barotropic fluid, we find that it is not in general related to the standard uniform density curvature perturbation $\zeta$; such a result conflicts with the claimed equivalence with $\Delta N$ formalism. Moreover, a similar analysis is done for the proposed non-perturbative generalization ${\cal R}_\mu$ of the comoving curvature perturbation ${\cal R}$. |
1407.5376 | Malik Rakhmanov | Malik Rakhmanov | On the round-trip time for a photon propagating in the field of a plane
gravitational wave | null | Classical and Quantum Gravity, vol. 26, p. 155010, (2009) | 10.1088/0264-9381/26/15/155010 | LIGO P070060 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A network of large-scale laser interferometers is currently employed for
searches of gravitational waves from various astrophysical sources. The
frequency dependence of the dynamic response of these detectors introduces
corrections to their antenna patterns which in principle can affect the outcome
of the associated data-analysis algorithms. The magnitude of these corrections
and the corresponding systematic errors have recently been estimated for
searches of periodic and stochastic gravitational waves (CQG 25 (2008) 184017).
However, the calculation of the detector response in that paper followed the
traditional semi-rigorous approach which does not properly take into account
the curved nature of spacetime. The question then arises as to whether the
results will be the same if the calculation is done within the rigorous
framework of general relativity. In this paper we provide such a derivation of
the response of the detectors to gravitational waves. We obtain the photon
propagation time from the solution of the equation for null geodesics and
calculate the corresponding phase delay by solving the eikonal equation for
curved spacetime. The calculations are then extended to include phase
amplification from multi-beam interference in Fabry-Perot resonators which play
an important role in the formation of the signal in these detectors.
| [
{
"created": "Mon, 21 Jul 2014 05:35:28 GMT",
"version": "v1"
}
] | 2014-07-22 | [
[
"Rakhmanov",
"Malik",
""
]
] | A network of large-scale laser interferometers is currently employed for searches of gravitational waves from various astrophysical sources. The frequency dependence of the dynamic response of these detectors introduces corrections to their antenna patterns which in principle can affect the outcome of the associated data-analysis algorithms. The magnitude of these corrections and the corresponding systematic errors have recently been estimated for searches of periodic and stochastic gravitational waves (CQG 25 (2008) 184017). However, the calculation of the detector response in that paper followed the traditional semi-rigorous approach which does not properly take into account the curved nature of spacetime. The question then arises as to whether the results will be the same if the calculation is done within the rigorous framework of general relativity. In this paper we provide such a derivation of the response of the detectors to gravitational waves. We obtain the photon propagation time from the solution of the equation for null geodesics and calculate the corresponding phase delay by solving the eikonal equation for curved spacetime. The calculations are then extended to include phase amplification from multi-beam interference in Fabry-Perot resonators which play an important role in the formation of the signal in these detectors. |
2204.00384 | Joshua Foo | Joshua Foo, Robert B. Mann, Magdalena Zych | Schr\"odinger's Black Hole Cat | 12 pages, Honourable Mention in the Gravity Research Foundation 2022
Awards for Essays on Gravitation | International Journal of Modern Physics D 31, 14 (2022) | 10.1142/S0218271822420160 | null | gr-qc hep-th quant-ph | http://creativecommons.org/licenses/by/4.0/ | In the absence of a fully-fledged theory of quantum gravity, we propose a
"bottom-up" framework for exploring quantum-gravitational physics by pairing
two of the most fundamental concepts of quantum theory and general relativity,
namely quantum superposition and spacetime. We show how to describe such
"spacetime superpositions" and explore effects they induce upon quantum matter.
Our approach capitalizes on standard tools of quantum field theory in curved
space, and allows us to calculate physical observables like transition
probabilities for a particle detector residing in curvature-superposed de
Sitter spacetime, or outside a mass-superposed black hole. Crucially, such
scenarios represent genuine quantum superpositions of spacetimes, in contrast
with superpositions of metrics which only differ by a coordinate transformation
and thus are not different according to general relativity.
| [
{
"created": "Fri, 1 Apr 2022 12:11:36 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Nov 2022 03:30:58 GMT",
"version": "v2"
}
] | 2022-12-20 | [
[
"Foo",
"Joshua",
""
],
[
"Mann",
"Robert B.",
""
],
[
"Zych",
"Magdalena",
""
]
] | In the absence of a fully-fledged theory of quantum gravity, we propose a "bottom-up" framework for exploring quantum-gravitational physics by pairing two of the most fundamental concepts of quantum theory and general relativity, namely quantum superposition and spacetime. We show how to describe such "spacetime superpositions" and explore effects they induce upon quantum matter. Our approach capitalizes on standard tools of quantum field theory in curved space, and allows us to calculate physical observables like transition probabilities for a particle detector residing in curvature-superposed de Sitter spacetime, or outside a mass-superposed black hole. Crucially, such scenarios represent genuine quantum superpositions of spacetimes, in contrast with superpositions of metrics which only differ by a coordinate transformation and thus are not different according to general relativity. |
2401.07307 | Lorenzo Fatibene | L.Fatibene, A.Orizzonte, A.Albano, S.Coriasco, M.Ferraris, S.Garruto,
N.Morandi | Introduction to Loop Quantum Gravity. The Holst's action and the
covariant formalism | 19 pages | International Journal of Geometric Methods in Modern Physics
(2024) | 10.1142/S0219887824400164 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We review Holst formalism and we discuss dynamical equivalence with standard
GR (in dimension 4). Holst formalism is written for a spin coframe field
$e^I_\mu$ and a $Spin(3,1)$-connection $\omega^{IJ}_\mu$ on spacetime $M$ and
it depends on the Holst parameter $\gamma\in \mathbb{R}-\{0\}$.
We show the model is dynamically equivalent to standard GR, in the sense that
up to a pointwise $Spin(3,1)$-gauge transformation acting on frame indices,
solutions of the two models are in one-to-one correspondence. Hence the two
models are classically equivalent.
One can also introduce new variables by splitting the spin connection into a
pair of a $Spin(3)$-connection $A^i_\mu$ and a $Spin(3)$-valued 1-form
$k^i_\mu$. The construction of these new variables relies on a particular
algebraic structure, called a reductive splitting. A reductive splitting is a
weaker structure than requiring that the gauge group splits as the products of
two sub-groups, as it happens in Euclidean signature in the selfdual
formulation originally introduced in this context by Ashtekar, and it still
allows to deal with the Lorentzian signature without resorting to
complexifications.
The reductive splitting of $SL(2, \mathbb{C})$ is not unique and it is
parameterized by a real parameter $\beta$, called the Immirzi parameter. The
splitting is here done on spacetime, not on space, to obtain a
$Spin(3)$-connection $A^i_\mu$, which is called the Barbero-Immirzi connection
on spacetime. One obtains a covariant model depending on the fields $(e^I_\mu,
A^i_\mu, k^i_\mu)$ which is again dynamically equivalent to standard GR (as
well as the Holst action).
Usually, in the literature one sets $\beta=\gamma$ for the sake of
simplicity. Here we keep the Holst and Immirzi parameters distinct to show that
eventually, only $\beta$ will survive in boundary field equations.
| [
{
"created": "Sun, 14 Jan 2024 14:55:39 GMT",
"version": "v1"
}
] | 2024-02-27 | [
[
"Fatibene",
"L.",
""
],
[
"Orizzonte",
"A.",
""
],
[
"Albano",
"A.",
""
],
[
"Coriasco",
"S.",
""
],
[
"Ferraris",
"M.",
""
],
[
"Garruto",
"S.",
""
],
[
"Morandi",
"N.",
""
]
] | We review Holst formalism and we discuss dynamical equivalence with standard GR (in dimension 4). Holst formalism is written for a spin coframe field $e^I_\mu$ and a $Spin(3,1)$-connection $\omega^{IJ}_\mu$ on spacetime $M$ and it depends on the Holst parameter $\gamma\in \mathbb{R}-\{0\}$. We show the model is dynamically equivalent to standard GR, in the sense that up to a pointwise $Spin(3,1)$-gauge transformation acting on frame indices, solutions of the two models are in one-to-one correspondence. Hence the two models are classically equivalent. One can also introduce new variables by splitting the spin connection into a pair of a $Spin(3)$-connection $A^i_\mu$ and a $Spin(3)$-valued 1-form $k^i_\mu$. The construction of these new variables relies on a particular algebraic structure, called a reductive splitting. A reductive splitting is a weaker structure than requiring that the gauge group splits as the products of two sub-groups, as it happens in Euclidean signature in the selfdual formulation originally introduced in this context by Ashtekar, and it still allows to deal with the Lorentzian signature without resorting to complexifications. The reductive splitting of $SL(2, \mathbb{C})$ is not unique and it is parameterized by a real parameter $\beta$, called the Immirzi parameter. The splitting is here done on spacetime, not on space, to obtain a $Spin(3)$-connection $A^i_\mu$, which is called the Barbero-Immirzi connection on spacetime. One obtains a covariant model depending on the fields $(e^I_\mu, A^i_\mu, k^i_\mu)$ which is again dynamically equivalent to standard GR (as well as the Holst action). Usually, in the literature one sets $\beta=\gamma$ for the sake of simplicity. Here we keep the Holst and Immirzi parameters distinct to show that eventually, only $\beta$ will survive in boundary field equations. |
2402.09513 | Nicholas DePorzio | Nicholas DePorzio, Lisa Randall, Zhong-Zhi Xianyu | Mass Beyond Measure: Eccentric Searches for Black Hole Populations | 13 pages, 10 figures | null | null | null | gr-qc astro-ph.CO astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Stellar mass binary black holes of unknown formation mechanism have been
observed, motivating new methods for distinguishing distinct black hole
populations. This work explores how the orbital eccentricity of stellar mass
binary black holes is a viable conduit for making such distinctions. Four
different production mechanisms, and their corresponding eccentricity
distributions, are studied in the context of an experimental landscape composed
of mHz (LISA), dHz (DECIGO), and Hz (LIGO) range gravitational wave detectors.
We expand on prior work considering these effects at fixed population
eccentricity. We show that a strong signal corresponding to subsets of
eccentric populations is effectively hidden from the mHz and dHz range
gravitational wave detectors without the incorporation of high eccentricity
waveform templates. Even with sufficiently large eccentricity templates, we
find dHz range experiments with a LISA-like level of sensitivity are unlikely
to aid in distinguishing different populations. We consider the degree to which
a mHz range detector like LISA can differentiate among black hole populations
independently and in concert with follow-up merger detection for binaries
coalescing within a 10 year period. We find that mHz range detectors, with only
$e < 0.01$ (nearly circular) sensitivity, can successfully discern eccentric
sub-populations except when attempting to distinguish very low eccentricity
distributions. In these cases where $e < 0.01$ sensitivity is insufficient, we
find that the increase in event counts resulting from $e < 0.1$ sensitivity
provides a statistically significant signal for discerning even these low
eccentricity sub-populations. While improvements offered by $e<0.1$ sensitivity
can be generally increased by $\mathcal{O}(1)$ factors with $e<0.4$
sensitivity, going beyond this in eccentricity sensitivity provides negligible
enhancement.
| [
{
"created": "Wed, 14 Feb 2024 19:00:01 GMT",
"version": "v1"
}
] | 2024-03-04 | [
[
"DePorzio",
"Nicholas",
""
],
[
"Randall",
"Lisa",
""
],
[
"Xianyu",
"Zhong-Zhi",
""
]
] | Stellar mass binary black holes of unknown formation mechanism have been observed, motivating new methods for distinguishing distinct black hole populations. This work explores how the orbital eccentricity of stellar mass binary black holes is a viable conduit for making such distinctions. Four different production mechanisms, and their corresponding eccentricity distributions, are studied in the context of an experimental landscape composed of mHz (LISA), dHz (DECIGO), and Hz (LIGO) range gravitational wave detectors. We expand on prior work considering these effects at fixed population eccentricity. We show that a strong signal corresponding to subsets of eccentric populations is effectively hidden from the mHz and dHz range gravitational wave detectors without the incorporation of high eccentricity waveform templates. Even with sufficiently large eccentricity templates, we find dHz range experiments with a LISA-like level of sensitivity are unlikely to aid in distinguishing different populations. We consider the degree to which a mHz range detector like LISA can differentiate among black hole populations independently and in concert with follow-up merger detection for binaries coalescing within a 10 year period. We find that mHz range detectors, with only $e < 0.01$ (nearly circular) sensitivity, can successfully discern eccentric sub-populations except when attempting to distinguish very low eccentricity distributions. In these cases where $e < 0.01$ sensitivity is insufficient, we find that the increase in event counts resulting from $e < 0.1$ sensitivity provides a statistically significant signal for discerning even these low eccentricity sub-populations. While improvements offered by $e<0.1$ sensitivity can be generally increased by $\mathcal{O}(1)$ factors with $e<0.4$ sensitivity, going beyond this in eccentricity sensitivity provides negligible enhancement. |
0711.4328 | George Ruppeiner | George Ruppeiner | Black Holes: Fermions at the Extremal Limit? | 12 page article, 1 Table, 1 Figure | null | null | null | gr-qc | null | I present exact results matching Kerr-Newman Black Hole thermodynamics in the
extremal limit to the two-dimensional Fermi Gas. Two dimensions are consistent
with the membrane paradigm of black holes. Key in the analysis is the
thermodynamic Riemannian curvature scalar $R$, negative for most ordinary
thermodynamic systems, including those near the critical point, but mostly
positive for the Kerr-Newman Black Hole and the Fermi Gas.
| [
{
"created": "Tue, 27 Nov 2007 18:59:30 GMT",
"version": "v1"
}
] | 2007-11-28 | [
[
"Ruppeiner",
"George",
""
]
] | I present exact results matching Kerr-Newman Black Hole thermodynamics in the extremal limit to the two-dimensional Fermi Gas. Two dimensions are consistent with the membrane paradigm of black holes. Key in the analysis is the thermodynamic Riemannian curvature scalar $R$, negative for most ordinary thermodynamic systems, including those near the critical point, but mostly positive for the Kerr-Newman Black Hole and the Fermi Gas. |
1910.03439 | Henrique de Oliveira | J. A. Crespo, H. P. de Oliveira and J. Winicour | The affine-null formulation of the gravitational equations: spherical
case | 18 pages, 10 figures | Phys. Rev. D 100, 104017 (2019) | 10.1103/PhysRevD.100.104017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new evolution algorithm for the characteristic initial value problem based
upon an affine parameter rather than the areal radial coordinate used in the
Bondi-Sachs formulation is applied in the spherically symmetric case to the
gravitational collapse of a massless scalar field. The advantages over the
Bondi-Sachs version are discussed, with particular emphasis on the application
to critical collapse. Unexpected quadratures lead to a simple evolution
algorithm based upon ordinary differential equations which can be integrated
along the null rays. For collapse to a black hole in a Penrose compactified
spacetime, these equations are regularized throughout the exterior and interior
of the horizon up to the final singularity. They are implemented as a global
numerical evolution code based upon the Galerkin method. New results regarding
the global properties of critical collapse are presented.
| [
{
"created": "Tue, 8 Oct 2019 14:57:49 GMT",
"version": "v1"
}
] | 2019-11-13 | [
[
"Crespo",
"J. A.",
""
],
[
"de Oliveira",
"H. P.",
""
],
[
"Winicour",
"J.",
""
]
] | A new evolution algorithm for the characteristic initial value problem based upon an affine parameter rather than the areal radial coordinate used in the Bondi-Sachs formulation is applied in the spherically symmetric case to the gravitational collapse of a massless scalar field. The advantages over the Bondi-Sachs version are discussed, with particular emphasis on the application to critical collapse. Unexpected quadratures lead to a simple evolution algorithm based upon ordinary differential equations which can be integrated along the null rays. For collapse to a black hole in a Penrose compactified spacetime, these equations are regularized throughout the exterior and interior of the horizon up to the final singularity. They are implemented as a global numerical evolution code based upon the Galerkin method. New results regarding the global properties of critical collapse are presented. |
1207.7041 | Foek Hioe | F. T. Hioe and David Kuebel | Characterization of all possible orbits in the Schwarzschild metric
revisited | 67 pages including 23 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | All possible orbital trajectories and their analytical expressions in the
Schwarzschild metric are presented in a single complete map characterized by
two dimensionless parameters. While three possible pairs of parameters with
different advantages are described, the parameter space that gives the most
convenient reduction to the Newtonian case is singled out and used which leads
to a new insight on Newtonian limits among other results. Numerous analytic
relations are presented. A comparison is made with the widely used formulation
and presentation given by S. Chandrasekhar.
| [
{
"created": "Mon, 30 Jul 2012 18:59:41 GMT",
"version": "v1"
}
] | 2012-07-31 | [
[
"Hioe",
"F. T.",
""
],
[
"Kuebel",
"David",
""
]
] | All possible orbital trajectories and their analytical expressions in the Schwarzschild metric are presented in a single complete map characterized by two dimensionless parameters. While three possible pairs of parameters with different advantages are described, the parameter space that gives the most convenient reduction to the Newtonian case is singled out and used which leads to a new insight on Newtonian limits among other results. Numerous analytic relations are presented. A comparison is made with the widely used formulation and presentation given by S. Chandrasekhar. |
gr-qc/9312027 | Bill Unruh | W.G. Unruh | Time Gravity and Quantum Mechanics | 50 pages. This paper was presented to a conference entitled "Time's
Arrow Today", a gathering of philosophers and physicists in 1992 | null | null | null | gr-qc | null | Time plays different roles in quantum mechanics and gravity. These roles are
examined and the problems that the conflict in the roles presents for quantum
gravity are briefly summarised.
| [
{
"created": "Fri, 17 Dec 1993 04:05:00 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Dec 1993 04:26:00 GMT",
"version": "v2"
}
] | 2008-02-03 | [
[
"Unruh",
"W. G.",
""
]
] | Time plays different roles in quantum mechanics and gravity. These roles are examined and the problems that the conflict in the roles presents for quantum gravity are briefly summarised. |
gr-qc/9710083 | Sanjay Jhingan | S. Jhingan | The Structure of Singularity in Gravitational Collapse | 3 pages, latex file, requires mprocl.sty, no figures. To appear in
the proceedings of the Eighth Marcel Grossmann Conference on General
Relativity (Jerusalem, Israel, 22-27 June 1997) | null | null | null | gr-qc | null | We will describe here the structure of singularity forming in gravitational
collapse of spherically symmetric inhomogeneous dust. Such a collapse is
described by the Tolman-Bondi-Lema{\^i}tre metric. The main new result here
relates, in a general way, the formation of black holes and naked
shell-focusing singularities resulting as the final fate of such a collapse to
the generic form of regular initial data. Such a data is characterized in terms
of the density and velocity profiles of the matter, specified on an initial
time slice from which the collapse commences. We show that given any generic
density profile at the initial time slice, there exists a corresponding
velocity profile which gives rise to a strong curvature naked singularity. This
establishes that strong naked singularities arise for a generic density
profile. We also establish here that similar results hold for black hole
formation as well. Keeping the model to be spherically symmetric we also
consider more general form of matter fields, i.e. equation of state $p =
k\rho$. We will analyse here the nature of non-central singularity forming due
to collapse of spherically symmetric perfect fluid subject to weak energy
condition.
| [
{
"created": "Fri, 17 Oct 1997 05:19:03 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Jhingan",
"S.",
""
]
] | We will describe here the structure of singularity forming in gravitational collapse of spherically symmetric inhomogeneous dust. Such a collapse is described by the Tolman-Bondi-Lema{\^i}tre metric. The main new result here relates, in a general way, the formation of black holes and naked shell-focusing singularities resulting as the final fate of such a collapse to the generic form of regular initial data. Such a data is characterized in terms of the density and velocity profiles of the matter, specified on an initial time slice from which the collapse commences. We show that given any generic density profile at the initial time slice, there exists a corresponding velocity profile which gives rise to a strong curvature naked singularity. This establishes that strong naked singularities arise for a generic density profile. We also establish here that similar results hold for black hole formation as well. Keeping the model to be spherically symmetric we also consider more general form of matter fields, i.e. equation of state $p = k\rho$. We will analyse here the nature of non-central singularity forming due to collapse of spherically symmetric perfect fluid subject to weak energy condition. |
1307.2935 | Ioannis Gkigkitzis Dr. | Ioannis Haranas, Omiros Ragos, Ioannis Gkigkitzis | The Lens-Thirring effect in the anomalistic period of celestial bodies | 12 pages, 5 Figures | null | null | null | gr-qc astro-ph.EP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the weak field and slow motion approximation, the general relativistic
field equations are linearized, resembling those of the electromagnetic theory.
In a way analogous to that of a moving charge generating a magnetic field, a
mass energy current can produce a gravitomagnetic field. In this contribution,
the motion of a secondary celestial body is studied under the influence of the
gravitomagnetic force generated by a spherical primary. More specifically, two
equations are derived to approximate the periastron time rate of change and its
total variation over one revolution (i.e., the difference between the
anomalistic period and the Keplerian period). Kinematically, this influence
results to an apsidal motion. The aforementioned quantities are numerically
estimated for Mercury, the companion star of the pulsar PSR 1913 plus 16, the
companion planet of the star HD 80606 and the artificial Earth satellite GRACE
A. The case of the artificial Earth satellite GRACE A is also considered, but
the results present a low degree of reliability from a practical standpoint.
| [
{
"created": "Wed, 10 Jul 2013 22:35:40 GMT",
"version": "v1"
}
] | 2013-07-12 | [
[
"Haranas",
"Ioannis",
""
],
[
"Ragos",
"Omiros",
""
],
[
"Gkigkitzis",
"Ioannis",
""
]
] | In the weak field and slow motion approximation, the general relativistic field equations are linearized, resembling those of the electromagnetic theory. In a way analogous to that of a moving charge generating a magnetic field, a mass energy current can produce a gravitomagnetic field. In this contribution, the motion of a secondary celestial body is studied under the influence of the gravitomagnetic force generated by a spherical primary. More specifically, two equations are derived to approximate the periastron time rate of change and its total variation over one revolution (i.e., the difference between the anomalistic period and the Keplerian period). Kinematically, this influence results to an apsidal motion. The aforementioned quantities are numerically estimated for Mercury, the companion star of the pulsar PSR 1913 plus 16, the companion planet of the star HD 80606 and the artificial Earth satellite GRACE A. The case of the artificial Earth satellite GRACE A is also considered, but the results present a low degree of reliability from a practical standpoint. |
1811.09518 | Piero Nicolini | Athanasios G. Tzikas, Piero Nicolini, Jonas Mureika and Bernard Carr | Primordial black holes in a dimensionally reduced universe | 26 pages, 8 figures; v2 published in JCAP | JCAP 1812 (2018) no.12, 033 | 10.1088/1475-7516/2018/12/033 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the spontaneous creation of primordial black holes in a
lower-dimensional expanding early universe. We use the no-boundary proposal to
construct instanton solutions for both the background and a black hole
nucleated inside this background. The resulting creation rate could lead to a
significant population of primordial black holes during the lower dimensional
phase. We also consider the subsequent evaporation of these dimensionally
reduced black holes and find that their temperature increases with mass,
whereas it decreases with mass for 4-dimensional black holes. This means that
they could leave stable sub-Planckian relics, which might in principle provide
the dark matter.
| [
{
"created": "Fri, 23 Nov 2018 15:23:51 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Dec 2018 16:56:29 GMT",
"version": "v2"
}
] | 2018-12-20 | [
[
"Tzikas",
"Athanasios G.",
""
],
[
"Nicolini",
"Piero",
""
],
[
"Mureika",
"Jonas",
""
],
[
"Carr",
"Bernard",
""
]
] | We investigate the spontaneous creation of primordial black holes in a lower-dimensional expanding early universe. We use the no-boundary proposal to construct instanton solutions for both the background and a black hole nucleated inside this background. The resulting creation rate could lead to a significant population of primordial black holes during the lower dimensional phase. We also consider the subsequent evaporation of these dimensionally reduced black holes and find that their temperature increases with mass, whereas it decreases with mass for 4-dimensional black holes. This means that they could leave stable sub-Planckian relics, which might in principle provide the dark matter. |
gr-qc/9706023 | Herbert Balasin | H.Balasin and W.Israel | Do Vortex Filaments in a Superfluid Neutron Star Produce Gravimagnetic
Forces ? | 11 pages, LaTeX with amslatex macros | Class.Quant.Grav. 16 (1999) 61-67 | 10.1088/0264-9381/16/1/004 | null | gr-qc | null | A general analysis of the gravitational dynamics of a medium with a
continuous distribution of vorticity indicates that the answer to the question
raised in the title is affirmative, contrary to a recent claim.
| [
{
"created": "Tue, 10 Jun 1997 06:58:18 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Balasin",
"H.",
""
],
[
"Israel",
"W.",
""
]
] | A general analysis of the gravitational dynamics of a medium with a continuous distribution of vorticity indicates that the answer to the question raised in the title is affirmative, contrary to a recent claim. |
1308.3977 | Vitaliy Voytik | Vitaliy Voytik | On the equations of the inverse kinematics problem | 12 p | STFI, 1 (2014) 28-36 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The paper derived differential equations which solve the problem of
restoration the motion parameters for a rigid reference frame from the known
proper acceleration and angular velocity of its origin as functions of proper
time. These equations are based on the well-known transformation to an
arbitrary rigid non-inertial reference frame, which generalized the Lorentz
transformation, takes into account the fact of her proper of Thomas precession
and rigid fixation of the metric form reference frame. The role of this problem
in physics is that all such reference frames found with the same
characteristics will have the same properties. Another important advantage of
these equations is that they allow you to find the motion of the non-inertial
reference frame with respect to an arbitrary inertial frame. The resulting
equations are nonlinear differential vector equation of the first order Riccati
type
\[\mathbf{{\dot{v}}'}=\frac{d\,\mathbf{{v}'}}{dt}=\mathbf{{W}'}-(\mathbf{{W}'{v}'})\mathbf{{v}'}-\mathbf{\Omega}'\times
\mathbf{{v}'}\] and known system of 3 equations \[\frac
{1}{2}\,e^{\alpha\lambda\nu }a^{ \lambda\beta } \frac{da^{\alpha \beta }
}{dt}=\omega'^{\nu }\,,\] which allows to determine the orientation of the
coordinate system for a given function on the right side of the equation \[
{\boldsymbol\omega
}'=\mathbf{\Omega}'-\frac{1-\sqrt{1-{{{{v}'}}^{2}}}}{{{{{v}'}}^{2}}}\,\mathbf{{v}'}\times
\mathbf{{W}'}\,,\] which are type angular velocity. The consequences of the
obtained equations have been successfully verified on the example of a
uniformly rotating disk.
| [
{
"created": "Mon, 19 Aug 2013 10:40:10 GMT",
"version": "v1"
},
{
"created": "Sat, 15 Apr 2023 17:08:32 GMT",
"version": "v2"
}
] | 2023-04-18 | [
[
"Voytik",
"Vitaliy",
""
]
] | The paper derived differential equations which solve the problem of restoration the motion parameters for a rigid reference frame from the known proper acceleration and angular velocity of its origin as functions of proper time. These equations are based on the well-known transformation to an arbitrary rigid non-inertial reference frame, which generalized the Lorentz transformation, takes into account the fact of her proper of Thomas precession and rigid fixation of the metric form reference frame. The role of this problem in physics is that all such reference frames found with the same characteristics will have the same properties. Another important advantage of these equations is that they allow you to find the motion of the non-inertial reference frame with respect to an arbitrary inertial frame. The resulting equations are nonlinear differential vector equation of the first order Riccati type \[\mathbf{{\dot{v}}'}=\frac{d\,\mathbf{{v}'}}{dt}=\mathbf{{W}'}-(\mathbf{{W}'{v}'})\mathbf{{v}'}-\mathbf{\Omega}'\times \mathbf{{v}'}\] and known system of 3 equations \[\frac {1}{2}\,e^{\alpha\lambda\nu }a^{ \lambda\beta } \frac{da^{\alpha \beta } }{dt}=\omega'^{\nu }\,,\] which allows to determine the orientation of the coordinate system for a given function on the right side of the equation \[ {\boldsymbol\omega }'=\mathbf{\Omega}'-\frac{1-\sqrt{1-{{{{v}'}}^{2}}}}{{{{{v}'}}^{2}}}\,\mathbf{{v}'}\times \mathbf{{W}'}\,,\] which are type angular velocity. The consequences of the obtained equations have been successfully verified on the example of a uniformly rotating disk. |
gr-qc/0502051 | Paolo Zampetti | Dino Boccaletti, Francesco Catoni, Roberto Cannata, Paolo Zampetti | Integrating the geodesic equations in the Schwarzschild and Kerr
space-times using Beltrami's "geometrical" method | 12 pages; corrected typos, journal-ref added | General Relativity and Gravitation, 37(12) (2005) 2261 | 10.1007/s10714-005-0203-z | null | gr-qc | null | We revisit a little known theorem due to Beltrami, through which the
integration of the geodesic equations of a curved manifold is accomplished by a
method which, even if inspired by the Hamilton-Jacobi method, is purely
geometric. The application of this theorem to the Schwarzschild and Kerr
metrics leads straightforwardly to the general solution of their geodesic
equations. This way of dealing with the problem is, in our opinion, very much
in keeping with the geometric spirit of general relativity. In fact, thanks to
this theorem we can integrate the geodesic equations by a geometrical method
and then verify that the classical conservation laws follow from these
equations.
| [
{
"created": "Fri, 11 Feb 2005 10:20:47 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Apr 2008 12:57:01 GMT",
"version": "v2"
}
] | 2008-04-03 | [
[
"Boccaletti",
"Dino",
""
],
[
"Catoni",
"Francesco",
""
],
[
"Cannata",
"Roberto",
""
],
[
"Zampetti",
"Paolo",
""
]
] | We revisit a little known theorem due to Beltrami, through which the integration of the geodesic equations of a curved manifold is accomplished by a method which, even if inspired by the Hamilton-Jacobi method, is purely geometric. The application of this theorem to the Schwarzschild and Kerr metrics leads straightforwardly to the general solution of their geodesic equations. This way of dealing with the problem is, in our opinion, very much in keeping with the geometric spirit of general relativity. In fact, thanks to this theorem we can integrate the geodesic equations by a geometrical method and then verify that the classical conservation laws follow from these equations. |
2001.04702 | Ali Kazemi | Ali Kazemi, Mahmood Roshan, Ivan De Martino, Mariafelicia De Laurentis | Jeans analysis in energy-momentum-squared gravity | 21 pages, 6 figs, Published (EPJC) | Eur. Phys. J. C (2020) 80: 150 | 10.1140/epjc/s10052-020-7662-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the Jeans analysis in the context of
energy-momentum-squared gravity (EMSG). More specifically we find the new Jeans
mass for non-rotating infinite mediums as the smallest mass scale for local
perturbations that can be stable against its own gravity. Furthermore, for
rotating mediums, specifically for rotating thin disks in the context of EMSG,
we find a new Toomre-like criterion for the local gravitational stability.
Finally, the results are applied to a hyper-massive neutron star, as an
astrophysical system. Using a simplified toy model we have shown that, for a
positive (negative) value of the EMSG parameter $\alpha$, the system is stable
(unstable) in a wide range of $\alpha$. On the other hand, no observational
evidence has been reported on the existence of local fragmentation in HMNS.
Naturally, this means that EMSG with positive $\alpha$ is more acceptable from
the physical point of view.
| [
{
"created": "Tue, 14 Jan 2020 10:29:51 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Feb 2020 06:01:36 GMT",
"version": "v2"
}
] | 2020-02-25 | [
[
"Kazemi",
"Ali",
""
],
[
"Roshan",
"Mahmood",
""
],
[
"De Martino",
"Ivan",
""
],
[
"De Laurentis",
"Mariafelicia",
""
]
] | In this paper, we study the Jeans analysis in the context of energy-momentum-squared gravity (EMSG). More specifically we find the new Jeans mass for non-rotating infinite mediums as the smallest mass scale for local perturbations that can be stable against its own gravity. Furthermore, for rotating mediums, specifically for rotating thin disks in the context of EMSG, we find a new Toomre-like criterion for the local gravitational stability. Finally, the results are applied to a hyper-massive neutron star, as an astrophysical system. Using a simplified toy model we have shown that, for a positive (negative) value of the EMSG parameter $\alpha$, the system is stable (unstable) in a wide range of $\alpha$. On the other hand, no observational evidence has been reported on the existence of local fragmentation in HMNS. Naturally, this means that EMSG with positive $\alpha$ is more acceptable from the physical point of view. |
1803.09649 | Wen-Biao Liu Prof. | Xin-Yang Wang, Jie Jiang, Wen-Biao Liu | Entropy in the interior of a Kerr black hole | 16 pages, 3 figures | null | 10.1088/1361-6382/aae276 | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Christodoulou and Rovelli have shown that the maximal interior volume of a
Schwarzschild black hole linearly grows with time. Recently, their conclusion
has been extended to the Reissner{-}Nordstr$\ddot{\text{o}}$m and Kerr black
holes. Meanwhile, the entropy of interior volume in a Schwarzschild black hole
has also been calculated. Here, a new method calculating the entropy of
interior volume of the black hole is given and it can be used in more general
cases. Using this method, the entropy associated with the volume of a Kerr
black hole is calculated and it is found that the entropy is proportional to
the Bekenstein-Hawking entropy in the early stage of black hole evaporation.
Using the differential form, the entropy of interior volume in a Schwarzschild
black hole is recalculated. It is shown that the proportionality coefficient
between the entropy and the Bekenstein-Hawking entropy is half of that given in
the previous literature. Moreover, the black hole information paradox is
brought up again and discussed.
| [
{
"created": "Fri, 23 Mar 2018 09:41:09 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Jun 2018 02:54:28 GMT",
"version": "v2"
}
] | 2018-10-24 | [
[
"Wang",
"Xin-Yang",
""
],
[
"Jiang",
"Jie",
""
],
[
"Liu",
"Wen-Biao",
""
]
] | Christodoulou and Rovelli have shown that the maximal interior volume of a Schwarzschild black hole linearly grows with time. Recently, their conclusion has been extended to the Reissner{-}Nordstr$\ddot{\text{o}}$m and Kerr black holes. Meanwhile, the entropy of interior volume in a Schwarzschild black hole has also been calculated. Here, a new method calculating the entropy of interior volume of the black hole is given and it can be used in more general cases. Using this method, the entropy associated with the volume of a Kerr black hole is calculated and it is found that the entropy is proportional to the Bekenstein-Hawking entropy in the early stage of black hole evaporation. Using the differential form, the entropy of interior volume in a Schwarzschild black hole is recalculated. It is shown that the proportionality coefficient between the entropy and the Bekenstein-Hawking entropy is half of that given in the previous literature. Moreover, the black hole information paradox is brought up again and discussed. |
0806.2365 | Mikhail Sheftel | Metin Arik and Mikhail B. Sheftel | Symmetry analysis and exact solutions of modified Brans-Dicke
cosmological equations | LaTeX2e source file, 14 pages, 7 references | Phys.Rev.D78:064067,2008 | 10.1103/PhysRevD.78.064067 | null | gr-qc astro-ph math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform a symmetry analysis of modified Brans-Dicke cosmological equations
and present exact solutions. We discuss how the solutions may help to build
models of cosmology where, for the early universe, the expansion is linear and
the equation of state just changes the expansion velocity but not the
linearity. For the late universe the expansion is exponential and the effect of
the equation of state on the rate of expansion is just to change the constant
Hubble parameter.
| [
{
"created": "Mon, 16 Jun 2008 18:45:44 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Arik",
"Metin",
""
],
[
"Sheftel",
"Mikhail B.",
""
]
] | We perform a symmetry analysis of modified Brans-Dicke cosmological equations and present exact solutions. We discuss how the solutions may help to build models of cosmology where, for the early universe, the expansion is linear and the equation of state just changes the expansion velocity but not the linearity. For the late universe the expansion is exponential and the effect of the equation of state on the rate of expansion is just to change the constant Hubble parameter. |
gr-qc/9812085 | Mamdouh Wanas | M.I.Wanas, M.Melek, and M.E.Kahil | Quantum Interference of Thermal Neutrons and Spin-Torsion Interaction | seven pages Tex file | Grav.Cosmol. 6 (2000) 319-322 | null | null | gr-qc quant-ph | null | The discrepancy of $0.8 %$ between theory and the COW-experiment is
interpreted. This is done by using a new path equation other than the geodesic
one. It is shown that this discrepancy is possibly due to a type of interaction
between the torsion, of space-time generated by the background field, and the
spin of the moving neutron. The results obtained are discussed and compared
with the experimental interpretation suggested by Arif et al. in 1994. As a
byproduct, an upper limit is imposed on the free parameter of the new path
equation used.
| [
{
"created": "Sat, 26 Dec 1998 11:55:07 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Wanas",
"M. I.",
""
],
[
"Melek",
"M.",
""
],
[
"Kahil",
"M. E.",
""
]
] | The discrepancy of $0.8 %$ between theory and the COW-experiment is interpreted. This is done by using a new path equation other than the geodesic one. It is shown that this discrepancy is possibly due to a type of interaction between the torsion, of space-time generated by the background field, and the spin of the moving neutron. The results obtained are discussed and compared with the experimental interpretation suggested by Arif et al. in 1994. As a byproduct, an upper limit is imposed on the free parameter of the new path equation used. |
2002.08358 | S. Danial Forghani | S. Danial Forghani and S. Habib Mazharimousavi | Thin-shell Wormholes with Ordinary Matter in Pure Gauss-Bonnet Gravity | 11 pages, 3 figures | null | 10.1088/1475-7516/2020/11/018 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we introduce higher dimensional thin-shell wormholes in pure
Gauss-Bonnet gravity. The focus is on thin-shell wormholes constructed by
$N\geq5$-dimensional spherically symmetric vacuum solutions. The results
suggest that, under certain conditions, it is possible to have thin-shell
wormholes that both satisfy the weak energy condition and be stable against
radial perturbations.
| [
{
"created": "Wed, 19 Feb 2020 11:49:38 GMT",
"version": "v1"
},
{
"created": "Sun, 13 Sep 2020 07:17:31 GMT",
"version": "v2"
}
] | 2020-11-25 | [
[
"Forghani",
"S. Danial",
""
],
[
"Mazharimousavi",
"S. Habib",
""
]
] | In this paper, we introduce higher dimensional thin-shell wormholes in pure Gauss-Bonnet gravity. The focus is on thin-shell wormholes constructed by $N\geq5$-dimensional spherically symmetric vacuum solutions. The results suggest that, under certain conditions, it is possible to have thin-shell wormholes that both satisfy the weak energy condition and be stable against radial perturbations. |
gr-qc/0507033 | Samuel Rocha Oliveira | L.A. D'Afonseca, P.S. Letelier and S.R. Oliveira | Geodesics around Weyl-Bach's Ring Solution | 8 figures, 14 pages. LaTeX w/ subfigure, graphicx | Class.Quant.Grav. 22 (2005) 3803-3814 | 10.1088/0264-9381/22/17/028 | null | gr-qc | null | We explore some of the gravitational features of a uniform ring both in the
Newtonian potential theory and in General Relativity. We use a spacetime
associated to a Weyl static solution of the vacuum Einstein's equations with
ring like singularity. The Newtonian motion for a test particle in the
gravitational field of the ring is studied and compared with the corresponding
geodesic motion in the given spacetime. We have found a relativistic peculiar
attraction: free falling particle geodesics are lead to the inner rim but never
hit the ring.
| [
{
"created": "Thu, 7 Jul 2005 21:45:42 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Aug 2005 20:52:44 GMT",
"version": "v2"
}
] | 2020-05-13 | [
[
"D'Afonseca",
"L. A.",
""
],
[
"Letelier",
"P. S.",
""
],
[
"Oliveira",
"S. R.",
""
]
] | We explore some of the gravitational features of a uniform ring both in the Newtonian potential theory and in General Relativity. We use a spacetime associated to a Weyl static solution of the vacuum Einstein's equations with ring like singularity. The Newtonian motion for a test particle in the gravitational field of the ring is studied and compared with the corresponding geodesic motion in the given spacetime. We have found a relativistic peculiar attraction: free falling particle geodesics are lead to the inner rim but never hit the ring. |
gr-qc/0105099 | Luc Blanchet | Luc Blanchet, Guillaume Faye, Bala R. Iyer, Benoit Joguet | Gravitational-Wave Inspiral of Compact Binary Systems to 7/2
Post-Newtonian Order | 12 pages, version which includes the correction of an Erratum to be
published in Phys. Rev. D (2005) | Phys.Rev.D65:061501,2002; Erratum-ibid.D71:129902,2005 | 10.1103/PhysRevD.65.061501 10.1103/PhysRevD.71.129902 | null | gr-qc | null | The inspiral of compact binaries, driven by gravitational-radiation reaction,
is investigated through 7/2 post-Newtonian (3.5PN) order beyond the quadrupole
radiation. We outline the derivation of the 3.5PN-accurate binary's
center-of-mass energy and emitted gravitational flux. The analysis consistently
includes the relativistic effects in the binary's equations of motion and
multipole moments, as well as the contributions of tails, and tails of tails,
in the wave zone. However the result is not fully determined because of some
physical incompleteness, present at the 3PN order, of the model of
point-particle and the associated Hadamard-type self-field regularization. The
orbital phase, whose prior knowledge is crucial for searching and analyzing the
inspiral signal, is computed from the standard energy balance argument.
| [
{
"created": "Sat, 26 May 2001 10:56:34 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Oct 2001 10:13:11 GMT",
"version": "v2"
},
{
"created": "Fri, 27 May 2005 14:48:08 GMT",
"version": "v3"
}
] | 2014-11-17 | [
[
"Blanchet",
"Luc",
""
],
[
"Faye",
"Guillaume",
""
],
[
"Iyer",
"Bala R.",
""
],
[
"Joguet",
"Benoit",
""
]
] | The inspiral of compact binaries, driven by gravitational-radiation reaction, is investigated through 7/2 post-Newtonian (3.5PN) order beyond the quadrupole radiation. We outline the derivation of the 3.5PN-accurate binary's center-of-mass energy and emitted gravitational flux. The analysis consistently includes the relativistic effects in the binary's equations of motion and multipole moments, as well as the contributions of tails, and tails of tails, in the wave zone. However the result is not fully determined because of some physical incompleteness, present at the 3PN order, of the model of point-particle and the associated Hadamard-type self-field regularization. The orbital phase, whose prior knowledge is crucial for searching and analyzing the inspiral signal, is computed from the standard energy balance argument. |
gr-qc/9602011 | null | John Ellis, N.E. Mavromatos, D.V. Nanopoulos, E.Winstanley | Quantum Decoherence in a Four-Dimensional Black Hole Background | 13-pages LATEX | Mod.Phys.Lett.A12:243-256,1997 | 10.1142/S0217732397000248 | CERN-TH.95-336,CTP-TAMU-04/95,OUTP-96--05P | gr-qc hep-th quant-ph | null | We display a logarithmic divergence in the density matrix of a scalar field
in the presence of an Einstein-Yang-Mills black hole in four dimensions. This
divergence is related to a previously-found logarithmic divergence in the
entropy of the scalar field, which cannot be absorbed into a renormalization of
the Hawking-Bekenstein entropy of the black hole. As the latter decays, the
logarithmic divergence induces a non-commutator term $\nd{\delta H}\rho$ in the
quantum Liouville equation for the density matrix $\rho$ of the scalar field,
leading to quantum decoherence. The order of magnitude of $\nd{\delta H}$ is
$\mu^2/M_P$, where $\mu$ is the mass of the scalar particle.
| [
{
"created": "Wed, 7 Feb 1996 19:25:19 GMT",
"version": "v1"
}
] | 2019-08-17 | [
[
"Ellis",
"John",
""
],
[
"Mavromatos",
"N. E.",
""
],
[
"Nanopoulos",
"D. V.",
""
],
[
"Winstanley",
"E.",
""
]
] | We display a logarithmic divergence in the density matrix of a scalar field in the presence of an Einstein-Yang-Mills black hole in four dimensions. This divergence is related to a previously-found logarithmic divergence in the entropy of the scalar field, which cannot be absorbed into a renormalization of the Hawking-Bekenstein entropy of the black hole. As the latter decays, the logarithmic divergence induces a non-commutator term $\nd{\delta H}\rho$ in the quantum Liouville equation for the density matrix $\rho$ of the scalar field, leading to quantum decoherence. The order of magnitude of $\nd{\delta H}$ is $\mu^2/M_P$, where $\mu$ is the mass of the scalar particle. |
1303.5520 | Yasusada Nambu | Ken-ichiro Kanai and Yasusada Nambu | Viewing Black Holes by Waves | 24 pages, final version to appear in Class. Quantum Grav | null | 10.1088/0264-9381/30/17/175002 | null | gr-qc astro-ph.HE physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study scattering of waves by black holes. Solving a massless scalar field
with a point source in the Schwarzschild spacetime, waves scattered by the
black hole is obtained numerically. We then reconstruct images of the black
hole from scattered wave data for specified scattering angles. For the forward
and the backward directions, obtained wave optical images of black holes show
rings that correspond to the black hole glories associated with existence of
the unstable circular photon orbit in the Schwarzschild spacetime.
| [
{
"created": "Fri, 22 Mar 2013 05:31:39 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Jul 2013 07:23:59 GMT",
"version": "v2"
}
] | 2015-06-15 | [
[
"Kanai",
"Ken-ichiro",
""
],
[
"Nambu",
"Yasusada",
""
]
] | We study scattering of waves by black holes. Solving a massless scalar field with a point source in the Schwarzschild spacetime, waves scattered by the black hole is obtained numerically. We then reconstruct images of the black hole from scattered wave data for specified scattering angles. For the forward and the backward directions, obtained wave optical images of black holes show rings that correspond to the black hole glories associated with existence of the unstable circular photon orbit in the Schwarzschild spacetime. |
1509.01529 | Sergey Paston | S.A. Paston, E.N. Semenova | External time canonical formalism for gravity in terms of embedding
theory | LaTeX, 17 pages | Gravitation and Cosmology, 2015, Vol. 21, No. 3, pp. 181-190 | 10.1134/S020228931503007X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The formulation of gravity theory is considered where space-time is a
4-dimensional surface in flat ten-dimensional space. The possibility of using
the "external" time (the time of ambient space) in this approach is
investigated. The transition to the "external" time is realized with the help
of partial gauge fixing, the coordinate condition which equates the timelike
coordinate of the surface and time of the ambient space. It is shown that by
using such a gauge condition in the action, the loss of any equations of motion
does not take place, although it can happen in the general case. A version of
the canonical formalism of the theory is studied in which certain additional
constraints are imposed, providing the equivalence of the approach under
consideration and general relativity. The corresponding first-class constraint
algebra is obtained. It is proved that using the gauge directly in the action
leads to the same result as gauge fixing in the constraint algebra, despite the
artificial introduction of some of the constraints into the theory. Application
of the "external" time may be useful for attempts to quantize the theory as
well as for studies in embedding theory where 4-dimensional surfaces fill the
whole ambient space and coordinates on the surfaces are not introduced.
| [
{
"created": "Fri, 4 Sep 2015 17:07:28 GMT",
"version": "v1"
}
] | 2015-09-07 | [
[
"Paston",
"S. A.",
""
],
[
"Semenova",
"E. N.",
""
]
] | The formulation of gravity theory is considered where space-time is a 4-dimensional surface in flat ten-dimensional space. The possibility of using the "external" time (the time of ambient space) in this approach is investigated. The transition to the "external" time is realized with the help of partial gauge fixing, the coordinate condition which equates the timelike coordinate of the surface and time of the ambient space. It is shown that by using such a gauge condition in the action, the loss of any equations of motion does not take place, although it can happen in the general case. A version of the canonical formalism of the theory is studied in which certain additional constraints are imposed, providing the equivalence of the approach under consideration and general relativity. The corresponding first-class constraint algebra is obtained. It is proved that using the gauge directly in the action leads to the same result as gauge fixing in the constraint algebra, despite the artificial introduction of some of the constraints into the theory. Application of the "external" time may be useful for attempts to quantize the theory as well as for studies in embedding theory where 4-dimensional surfaces fill the whole ambient space and coordinates on the surfaces are not introduced. |
1906.00913 | Abhay Ashtekar | Abhay Ashtekar, Tommaso De Lorenzo and Neev Khera | Compact binary coalescences: Constraints on waveforms | 25 pages, 1 figure. The main results are the same as in V1. Focus of
the article improved by expanding the material addressed to the waveform
community and dropping the one primarily addressed to mathematical
relativists. Discussion updated in view of new results of [46] - [48] | General Relativity and Gravitation 52, 107 (2020) | 10.1007/s10714-020-02764-1 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waveforms for compact binary coalescences (CBCs) have been
invaluable for detections by the LIGO-Virgo collaboration. They are obtained by
a combination of semi-analytical models and numerical simulations. So far
systematic errors arising from these procedures appear to be less than
statistical ones. However, the significantly enhanced sensitivity of the new
detectors that will become operational in the near future will require
waveforms to be much more accurate. This task would be facilitated if one has a
variety of cross-checks to \emph{evaluate} accuracy, particularly in the
regions of parameter space where numerical simulations are sparse. Currently
errors are estimated by comparing the candidate waveforms with the numerical
relativity (NR) ones, which are taken to be exact. The goal of this paper is to
propose a qualitatively different tool. We show that full non-linear general
relativity (GR) imposes an infinite number of sharp constraints on the CBC
waveforms. These can provide clear-cut measures to evaluate the accuracy of
candidate waveforms against exact GR, help find systematic errors, and also
provide external checks on NR simulations themselves.
| [
{
"created": "Mon, 3 Jun 2019 16:29:34 GMT",
"version": "v1"
},
{
"created": "Wed, 29 Jul 2020 13:58:57 GMT",
"version": "v2"
},
{
"created": "Tue, 12 Jan 2021 17:55:02 GMT",
"version": "v3"
}
] | 2021-01-13 | [
[
"Ashtekar",
"Abhay",
""
],
[
"De Lorenzo",
"Tommaso",
""
],
[
"Khera",
"Neev",
""
]
] | Gravitational waveforms for compact binary coalescences (CBCs) have been invaluable for detections by the LIGO-Virgo collaboration. They are obtained by a combination of semi-analytical models and numerical simulations. So far systematic errors arising from these procedures appear to be less than statistical ones. However, the significantly enhanced sensitivity of the new detectors that will become operational in the near future will require waveforms to be much more accurate. This task would be facilitated if one has a variety of cross-checks to \emph{evaluate} accuracy, particularly in the regions of parameter space where numerical simulations are sparse. Currently errors are estimated by comparing the candidate waveforms with the numerical relativity (NR) ones, which are taken to be exact. The goal of this paper is to propose a qualitatively different tool. We show that full non-linear general relativity (GR) imposes an infinite number of sharp constraints on the CBC waveforms. These can provide clear-cut measures to evaluate the accuracy of candidate waveforms against exact GR, help find systematic errors, and also provide external checks on NR simulations themselves. |
gr-qc/0211037 | Adrian Butscher | Adrian Butscher | Perturbative Solutions of the Extended Constraint Equations in General
Relativity | This third and final version has been accepted for publication in
Communications in Mathematical Physics | Commun.Math.Phys.272:1-23,2007 | 10.1007/s00220-007-0204-8 | null | gr-qc math.DG | null | The extended constraint equations arise as a special case of the conformal
constraint equations that are satisfied by an initial data hypersurface $Z$ in
an asymptotically simple spacetime satisfying the vacuum conformal Einstein
equations developed by H. Friedrich. The extended constraint equations consist
of a quasi-linear system of partial differential equations for the induced
metric, the second fundamental form and two other tensorial quantities defined
on $Z$, and are equivalent to the usual constraint equations that $Z$ satisfies
as a spacelike hypersurface in a spacetime satisfying Einstein's vacuum
equation. This article develops a method for finding perturbative,
asymptotically flat solutions of the extended constraint equations in a
neighbourhood of the flat solution on Euclidean space. This method is
fundamentally different from the `classical' method of Lichnerowicz and York
that is used to solve the usual constraint equations.
| [
{
"created": "Mon, 11 Nov 2002 20:38:22 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Oct 2003 05:18:59 GMT",
"version": "v2"
},
{
"created": "Fri, 8 Sep 2006 18:33:12 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Butscher",
"Adrian",
""
]
] | The extended constraint equations arise as a special case of the conformal constraint equations that are satisfied by an initial data hypersurface $Z$ in an asymptotically simple spacetime satisfying the vacuum conformal Einstein equations developed by H. Friedrich. The extended constraint equations consist of a quasi-linear system of partial differential equations for the induced metric, the second fundamental form and two other tensorial quantities defined on $Z$, and are equivalent to the usual constraint equations that $Z$ satisfies as a spacelike hypersurface in a spacetime satisfying Einstein's vacuum equation. This article develops a method for finding perturbative, asymptotically flat solutions of the extended constraint equations in a neighbourhood of the flat solution on Euclidean space. This method is fundamentally different from the `classical' method of Lichnerowicz and York that is used to solve the usual constraint equations. |
1605.02369 | Luis Lehner | Luis Lehner, Steven L. Liebling, Carlos Palenzuela and Patrick Motl | The $m=1$ instability \& gravitational wave signal in binary neutron
star mergers | 9 pages, 5 figures. Update to match published version; in particular
the previous version used an incorrect noise curve which affected slightly
the conclusions. This is now fixed | Phys. Rev. D 94, 043003 (2016) | 10.1103/PhysRevD.94.043003 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the development and detectability of the $m=1$ instability in the
remnant of binary neutron star mergers. The detection of the gravitational mode
associated with the $m=1$ degree of freedom could potentially reveal details of
the equation of state. We analyze the post-merger epoch of simulations of both
equal and non-equal mass neutron star mergers using three realistic,
microphysical equations of state and neutrino cooling. Our studies show such an
instability develops generically and within a short dynamical time to strengths
that are comparable or stronger than the $m=2$ mode which is the strongest
during the early post-merger stage. We estimate the signal to noise ratio that
might be obtained for the $m=1$ mode and discuss the prospects for observing
this signal with available Earth-based detectors. Because the $m=1$ occurs at
roughly half the frequency of the more powerful $m=2$ signal and because it can
potentially be long-lived, targeted searches could be devised to observe it. We
estimate that with constant amplitude direct detection of the mode could occur
up to a distance of roughly $14\,\mathrm{Mpc}$ whereas a search triggered by
the inspiral signal could extend this distance to roughly $100\,\mathrm{Mpc}$.
| [
{
"created": "Sun, 8 May 2016 21:21:31 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Aug 2016 12:45:50 GMT",
"version": "v2"
}
] | 2016-08-22 | [
[
"Lehner",
"Luis",
""
],
[
"Liebling",
"Steven L.",
""
],
[
"Palenzuela",
"Carlos",
""
],
[
"Motl",
"Patrick",
""
]
] | We examine the development and detectability of the $m=1$ instability in the remnant of binary neutron star mergers. The detection of the gravitational mode associated with the $m=1$ degree of freedom could potentially reveal details of the equation of state. We analyze the post-merger epoch of simulations of both equal and non-equal mass neutron star mergers using three realistic, microphysical equations of state and neutrino cooling. Our studies show such an instability develops generically and within a short dynamical time to strengths that are comparable or stronger than the $m=2$ mode which is the strongest during the early post-merger stage. We estimate the signal to noise ratio that might be obtained for the $m=1$ mode and discuss the prospects for observing this signal with available Earth-based detectors. Because the $m=1$ occurs at roughly half the frequency of the more powerful $m=2$ signal and because it can potentially be long-lived, targeted searches could be devised to observe it. We estimate that with constant amplitude direct detection of the mode could occur up to a distance of roughly $14\,\mathrm{Mpc}$ whereas a search triggered by the inspiral signal could extend this distance to roughly $100\,\mathrm{Mpc}$. |
gr-qc/9610033 | null | M. Tsuda and T. Shirafuji | Structure of the field equations in N = 1 chiral supergravity | 19 pages, latex | null | null | STUPP-96-149 | gr-qc | null | We study the structure of linearized field equations in $N = 1$ chiral
supergravity (SUGRA) with a complex tetrad, as a preliminary to introducing
additional auxiliary fields in order that the supersymmetry (SUSY) algebra
close off shell. We follow the first-order formulation we have recently
constructed using the method of the usual $N = 1$ SUGRA. In particular, we see
how the real and imaginary parts of the complex tetrad are coupled to matter
fields in the weak field approximation. Starting from the linearized (free)
theory of $N = 1$ chiral SUGRA, we then construct a Lagrangian which is
invariant under local SUSY transformations to zeroth order of the gravitational
constant, and compare the results with the linearized field equations.
| [
{
"created": "Wed, 16 Oct 1996 04:07:44 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Tsuda",
"M.",
""
],
[
"Shirafuji",
"T.",
""
]
] | We study the structure of linearized field equations in $N = 1$ chiral supergravity (SUGRA) with a complex tetrad, as a preliminary to introducing additional auxiliary fields in order that the supersymmetry (SUSY) algebra close off shell. We follow the first-order formulation we have recently constructed using the method of the usual $N = 1$ SUGRA. In particular, we see how the real and imaginary parts of the complex tetrad are coupled to matter fields in the weak field approximation. Starting from the linearized (free) theory of $N = 1$ chiral SUGRA, we then construct a Lagrangian which is invariant under local SUSY transformations to zeroth order of the gravitational constant, and compare the results with the linearized field equations. |
gr-qc/0201099 | Israel Quiros | Israel Quiros (Physics Department. Las Villas Central University.
Santa Clara) | Scale Invariant Kaluza-Klein Theory and the Fate of the Gravitational
Collapse | 10 pages, latex, no figures | null | null | null | gr-qc | null | Pushing forward the similitudes between the gravitational collapse and the
expansion of the universe (in the reversed sense of time), it should be
expected that, during the collapse, eventually, a spacetime domain would be
reached where attained energy scales are very high. In consequence some of the
compactified extra dimensions may be decompactified and some presently broken
symmetries may be restored. A more fundamental theory (of which Einstein's
theory is a symmetry broken phase) is then expected to take account of further
description of the collapse. I propose a simple (classical) model for the
description of the late stages of the gravitational collapse: A non-Riemannian,
scale-invariant version of 5-dimensional Kaluza-Klein theory in which the
standard Riemann structure of the higher-dimensional manifold is replaced by a
Weyl-integrable one. A class of solutions, that generalize the "soliton" one by
Gross and Perry and Davidson and Owen, is found. This class contains both naked
singularities and wormhole solutions. On physical grounds it is argued that a
wormhole is the most reasonable destiny of the gravitational collapse.
| [
{
"created": "Thu, 31 Jan 2002 03:47:53 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Quiros",
"Israel",
"",
"Physics Department. Las Villas Central University.\n Santa Clara"
]
] | Pushing forward the similitudes between the gravitational collapse and the expansion of the universe (in the reversed sense of time), it should be expected that, during the collapse, eventually, a spacetime domain would be reached where attained energy scales are very high. In consequence some of the compactified extra dimensions may be decompactified and some presently broken symmetries may be restored. A more fundamental theory (of which Einstein's theory is a symmetry broken phase) is then expected to take account of further description of the collapse. I propose a simple (classical) model for the description of the late stages of the gravitational collapse: A non-Riemannian, scale-invariant version of 5-dimensional Kaluza-Klein theory in which the standard Riemann structure of the higher-dimensional manifold is replaced by a Weyl-integrable one. A class of solutions, that generalize the "soliton" one by Gross and Perry and Davidson and Owen, is found. This class contains both naked singularities and wormhole solutions. On physical grounds it is argued that a wormhole is the most reasonable destiny of the gravitational collapse. |
1510.03474 | Vladimir Dergachev Ph.D. | J. Aasi, B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F.
Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B.
Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Ain,
P. Ajith, B. Allen, A. Allocca, D. V. Amariutei, M. Andersen, S. B. Anderson,
W. G. Anderson, K. Arai, M. C. Araya, C. C. Arceneaux, J. S. Areeda, N.
Arnaud, G. Ashton, S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert, S. Babak,
P. T. Baker, F. Baldaccini, G. Ballardin, S. W. Ballmer, J. C. Barayoga, S.
E. Barclay, B. C. Barish, D. Barker, F. Barone, B. Barr, L. Barsotti, M.
Barsuglia, J. Bartlett, M. A. Barton, I. Bartos, R. Bassiri, A. Basti, J. C.
Batch, C. Baune, V. Bavigadda, B. Behnke, M. Bejger, C. Belczynski, A. S.
Bell, B. K. Berger, J. Bergman, G. Bergmann, C. P. L. Berry, D. Bersanetti,
A. Bertolini, J. Betzwieser, S. Bhagwat, R. Bhandare, I. A. Bilenko, G.
Billingsley, J. Birch, R. Birney, S. Biscans, M. Bitossi, C. Biwer, M. A.
Bizouard, J. K. Blackburn, C. D. Blair, D. Blair, S. Bloemen, O. Bock, T. P.
Bodiya, M. Boer, G. Bogaert, P. Bojtos, C. Bond, F. Bondu, R. Bonnand, R.
Bork, M. Born, V. Boschi, Sukanta Bose, C. Bradaschia, P. R. Brady, V. B.
Braginsky, M. Branchesi, V. Branco, J. E. Brau, T. Briant, A. Brillet, M.
Brinkmann, V. Brisson, P. Brockill, A. F. Brooks, D. A. Brown, D. Brown, D.
D. Brown, N. M. Brown, C. C. Buchanan, A. Buikema, T. Bulik, H. J. Bulten, A.
Buonanno, D. Buskulic, C. Buy, R. L. Byer, L. Cadonati, G. Cagnoli, J.
Calder\'on Bustillo, E. Calloni, J. B. Camp, K. C. Cannon, J. Cao, C. D.
Capano, E. Capocasa, F. Carbognani, S. Caride, J. Casanueva Diaz, C.
Casentini, S. Caudill, M. Cavagli\`a, F. Cavalier, R. Cavalieri, C. Celerier,
G. Cella, C. Cepeda, L. Cerboni Baiardi, G. Cerretani, E. Cesarini, R.
Chakraborty, T. Chalermsongsak, S. J. Chamberlin, S. Chao, P. Charlton, E.
Chassande-Mottin, X. Chen, Y. Chen, C. Cheng, A. Chincarini, A. Chiummo, H.
S. Cho, M. Cho, J. H. Chow, N. Christensen, Q. Chu, S. Chua, S. Chung, G.
Ciani, F. Clara, J. A. Clark, F. Cleva, E. Coccia, P.-F. Cohadon, A. Colla,
C. G. Collette, M. Colombini, M. Constancio Jr., A. Conte, L. Conti, D. Cook,
T. R. Corbitt, N. Cornish, A. Corsi, C. A. Costa, M. W. Coughlin, S. B.
Coughlin, J.-P. Coulon, S. T. Countryman, P. Couvares, D. M. Coward, M. J.
Cowart, D. C. Coyne, R. Coyne, K. Craig, J. D. E. Creighton, T. Creighton, J.
Cripe, S. G. Crowder, A. Cumming, L. Cunningham, E. Cuoco, T. Dal Canton, M.
D. Damjanic, S. L. Danilishin, S. D'Antonio, K. Danzmann, N. S. Darman, V.
Dattilo, I. Dave, H. P. Daveloza, M. Davier, G. S. Davies, E. J. Daw, R. Day,
D. DeBra, G. Debreczeni, J. Degallaix, M. De Laurentis, S. Del\'eglise, W.
Del Pozzo, T. Denker, T. Dent, H. Dereli, V. Dergachev, R. De Rosa, R. T.
DeRosa, R. DeSalvo, S. Dhurandhar, M. C. D\'iaz, L. Di Fiore, M. Di Giovanni,
A. Di Lieto, I. Di Palma, A. Di Virgilio, G. Dojcinoski, V. Dolique, E.
Dominguez, F. Donovan, K. L. Dooley, S. Doravari, R. Douglas, T. P. Downes,
M. Drago, R. W. P. Drever, J. C. Driggers, Z. Du, M. Ducrot, S. E. Dwyer, T.
B. Edo, M. C. Edwards, M. Edwards, A. Effler, H.-B. Eggenstein, P. Ehrens, J.
M. Eichholz, S. S. Eikenberry, R. C. Essick, T. Etzel, M. Evans, T. M. Evans,
R. Everett, M. Factourovich, V. Fafone, S. Fairhurst, Q. Fang, S. Farinon, B.
Farr, W. M. Farr, M. Favata, M. Fays, H. Fehrmann, M. M. Fejer, D. Feldbaum,
I. Ferrante, E. C. Ferreira, F. Ferrini, F. Fidecaro, I. Fiori, R. P. Fisher,
R. Flaminio, J.-D. Fournier, S. Franco, S. Frasca, F. Frasconi, M. Frede, Z.
Frei, A. Freise, R. Frey, T. T. Fricke, P. Fritschel, V. V. Frolov, P. Fulda,
M. Fyffe, H. A. G. Gabbard, J. R. Gair, L. Gammaitoni, S. G. Gaonkar, F.
Garufi, A. Gatto, N. Gehrels, G. Gemme, B. Gendre, E. Genin, A. Gennai, L.
\'A. Gergely, V. Germain, A. Ghosh, S. Ghosh, J. A. Giaime, K. D. Giardina,
A. Giazotto, J. R. Gleason, E. Goetz, R. Goetz, L. Gondan, G. Gonz\'alez, J.
Gonzalez, A. Gopakumar, N. A. Gordon, M. L. Gorodetsky, S. E. Gossan, M.
Gosselin, S. Go{\ss}ler, R. Gouaty, C. Graef, P. B. Graff, M. Granata, A.
Grant, S. Gras, C. Gray, G. Greco, P. Groot, H. Grote, K. Grover, S.
Grunewald, G. M. Guidi, C. J. Guido, X. Guo, A. Gupta, M. K. Gupta, K. E.
Gushwa, E. K. Gustafson, R. Gustafson, J. J. Hacker, B. R. Hall, E. D. Hall,
D. Hammer, G. Hammond, M. Haney, M. M. Hanke, J. Hanks, C. Hanna, M. D.
Hannam, J. Hanson, T. Hardwick, J. Harms, G. M. Harry, I. W. Harry, M. J.
Hart, M. T. Hartman, C.-J. Haster, K. Haughian, A. Heidmann, M. C. Heintze,
H. Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, J. Hennig, A. W.
Heptonstall, M. Heurs, S. Hild, D. Hoak, K. A. Hodge, J. Hoelscher-Obermaier,
D. Hofman, S. E. Hollitt, K. Holt, P. Hopkins, D. J. Hosken, J. Hough, E. A.
Houston, E. J. Howell, Y. M. Hu, S. Huang, E. A. Huerta, D. Huet, B. Hughey,
S. Husa, S. H. Huttner, M. Huynh, T. Huynh-Dinh, A. Idrisy, N. Indik, D. R.
Ingram, R. Inta, G. Islas, J. C. Isler, T. Isogai, B. R. Iyer, K. Izumi, M.
B. Jacobson, H. Jang, P. Jaranowski, S. Jawahar, Y. Ji, F. Jim\'enez-Forteza,
W. W. Johnson, D. I. Jones, R. Jones, R.J.G. Jonker, L. Ju, Haris K, V.
Kalogera, S. Kandhasamy, G. Kang, J. B. Kanner, S. Karki, J. L. Karlen, M.
Kasprzack, E. Katsavounidis, W. Katzman, S. Kaufer, T. Kaur, K. Kawabe, F.
Kawazoe, F. K\'ef\'elian, M. S. Kehl, D. Keitel, N. Kelecsenyi, D. B. Kelley,
W. Kells, J. Kerrigan, J. S. Key, F. Y. Khalili, Z. Khan, E. A. Khazanov, N.
Kijbunchoo, C. Kim, K. Kim, N. G. Kim, N. Kim, Y.-M. Kim, E. J. King, P. J.
King, D. L. Kinzel, J. S. Kissel, S. Klimenko, J. T. Kline, S. M.
Koehlenbeck, K. Kokeyama, S. Koley, V. Kondrashov, M. Korobko, W. Z. Korth,
I. Kowalska, D. B. Kozak, V. Kringel, B. Krishnan, A. Kr\'olak, C. Krueger,
G. Kuehn, A. Kumar, P. Kumar, L. Kuo, A. Kutynia, B. D. Lackey, M. Landry, B.
Lantz, P. D. Lasky, A. Lazzarini, C. Lazzaro, P. Leaci, S. Leavey, E. O.
Lebigot, C. H. Lee, H. K. Lee, H. M. Lee, J. Lee, J. P. Lee, M. Leonardi, J.
R. Leong, N. Leroy, N. Letendre, Y. Levin, B. M. Levine, J. B. Lewis, T. G.
F. Li, A. Libson, A. C. Lin, T. B. Littenberg, N. A. Lockerbie, V. Lockett,
D. Lodhia, J. Logue, A. L. Lombardi, M. Lorenzini, V. Loriette, M. Lormand,
G. Losurdo, J. D. Lough, M. J. Lubinski (Ski), H. L\"uck, A. P. Lundgren, J.
Luo, R. Lynch, Y. Ma, J. Macarthur, E. P. Macdonald, T. MacDonald, B.
Machenschalk, M. MacInnis, D. M. Macleod, D. X. Madden-Fong, F. Maga\
na-Sandoval, R. M. Magee, M. Mageswaran, E. Majorana, I. Maksimovic, V.
Malvezzi, N. Man, I. Mandel, V. Mandic, V. Mangano, N. M. Mangini, G. L.
Mansell, M. Manske, M. Mantovani, F. Marchesoni, F. Marion, S. M\'arka, Z.
M\'arka, A. S. Markosyan, E. Maros, F. Martelli, L. Martellini, I. W. Martin,
R. M. Martin, D. V. Martynov, J. N. Marx, K. Mason, A. Masserot, T. J.
Massinger, F. Matichard, L. Matone, N. Mavalvala, N. Mazumder, G. Mazzolo, R.
McCarthy, D. E. McClelland, S. McCormick, S. C. McGuire, G. McIntyre, J.
McIver, S. T. McWilliams, D. Meacher, G. D. Meadors, M. Mehmet, J. Meidam, M.
Meinders, A. Melatos, G. Mendell, R. A. Mercer, M. Merzougui, S. Meshkov, C.
Messenger, C. Messick, P. M. Meyers, F. Mezzani, H. Miao, C. Michel, H.
Middleton, E. E. Mikhailov, L. Milano, J. Miller, M. Millhouse, Y. Minenkov,
J. Ming, S. Mirshekari, C. Mishra, S. Mitra, V. P. Mitrofanov, G.
Mitselmakher, R. Mittleman, B. Moe, A. Moggi, M. Mohan, S. R. P. Mohapatra,
M. Montani, B. C. Moore, D. Moraru, G. Moreno, S. R. Morriss, K. Mossavi, B.
Mours, C. M. Mow-Lowry, C. L. Mueller, G. Mueller, A. Mukherjee, S.
Mukherjee, A. Mullavey, J. Munch, D. J. Murphy IV, P. G. Murray, A. Mytidis,
M. F. Nagy, I. Nardecchia, L. Naticchioni, R. K. Nayak, V. Necula, K.
Nedkova, G. Nelemans, M. Neri, G. Newton, T. T. Nguyen, A. B. Nielsen, A.
Nitz, F. Nocera, D. Nolting, M. E. N. Normandin, L. K. Nuttall, E. Ochsner,
J. O'Dell, E. Oelker, G. H. Ogin, J. J. Oh, S. H. Oh, F. Ohme, M. Okounkova,
P. Oppermann, R. Oram, B. O'Reilly, W. E. Ortega, R. O'Shaughnessy, D. J.
Ottaway, R. S. Ottens, H. Overmier, B. J. Owen, C. T. Padilla, A. Pai, S. A.
Pai, J. R. Palamos, O. Palashov, C. Palomba, A. Pal-Singh, H. Pan, Y. Pan, C.
Pankow, F. Pannarale, B. C. Pant, F. Paoletti, M. A. Papa, H. R. Paris, A.
Pasqualetti, R. Passaquieti, D. Passuello, Z. Patrick, M. Pedraza, L.
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Predoi, S. S. Premachandra, T. Prestegard, L. R. Price, M. Prijatelj, M.
Principe, S. Privitera, R. Prix, G. A. Prodi, L. Prokhorov, O. Puncken, M.
Punturo, P. Puppo, M. P\"urrer, J. Qin, V. Quetschke, E. A. Quintero, R.
Quitzow-James, F. J. Raab, D. S. Rabeling, I. R\'acz, H. Radkins, P. Raffai,
S. Raja, M. Rakhmanov, P. Rapagnani, V. Raymond, M. Razzano, V. Re, C. M.
Reed, T. Regimbau, L. Rei, S. Reid, D. H. Reitze, F. Ricci, K. Riles, N. A.
Robertson, R. Robie, F. Robinet, A. Rocchi, A. S. Rodger, L. Rolland, J. G.
Rollins, V. J. Roma, R. Romano, G. Romanov, J. H. Romie, D. Rosi\'nska, S.
Rowan, A. R\"udiger, P. Ruggi, K. Ryan, S. Sachdev, T. Sadecki, L. Sadeghian,
M. Saleem, F. Salemi, L. Sammut, E. Sanchez, V. Sandberg, J. R. Sanders, I.
Santiago-Prieto, B. Sassolas, P. R. Saulson, R. Savage, A. Sawadsky, P.
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Sch\"onbeck, E. Schreiber, D. Schuette, B. F. Schutz, J. Scott, S. M. Scott,
D. Sellers, D. Sentenac, V. Sequino, A. Sergeev, G. Serna, A. Sevigny, D. A.
Shaddock, P. Shaffery, S. Shah, M. S. Shahriar, M. Shaltev, Z. Shao, B.
Shapiro, P. Shawhan, D. H. Shoemaker, T. L. Sidery, K. Siellez, X. Siemens,
D. Sigg, A. D. Silva, D. Simakov, A. Singer, L. P. Singer, R. Singh, A. M.
Sintes, B. J. J. Slagmolen, J. R. Smith, N. D. Smith, R. J. E. Smith, E. J.
Son, B. Sorazu, T. Souradeep, A. K. Srivastava, A. Staley, J. Stebbins, M.
Steinke, J. Steinlechner, S. Steinlechner, D. Steinmeyer, B. C. Stephens, S.
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Strauss, S. Strigin, R. Sturani, A. L. Stuver, T. Z. Summerscales, L. Sun, P.
J. Sutton, B. L. Swinkels, M. J. Szczepanczyk, M. Tacca, D. Talukder, D. B.
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Veitch, K. Venkateswara, D. Verkindt, F. Vetrano, A. Vicer\'e, J.-Y. Vinet,
S. Vitale, T. Vo, H. Vocca, C. Vorvick, W. D. Vousden, S. P. Vyatchanin, A.
R. Wade, M. Wade, L. E. Wade IV, M. Walker, L. Wallace, S. Walsh, G. Wang, H.
Wang, M. Wang, X. Wang, R. L. Ward, J. Warner, M. Was, B. Weaver, L.-W. Wei,
M. Weinert, A. J. Weinstein, R. Weiss, T. Welborn, L. Wen, P. We{\ss}els, T.
Westphal, K. Wette, J. T. Whelan, D. J. White, B. F. Whiting, K. J. Williams,
L. Williams, R. D. Williams, A. R. Williamson, J. L. Willis, B. Willke, M. H.
Wimmer, W. Winkler, C. C. Wipf, H. Wittel, G. Woan, J. Worden, J. Yablon, I.
Yakushin, W. Yam, H. Yamamoto, C. C. Yancey, M. Yvert, A. Zadro\.zny, L.
Zangrando, M. Zanolin, J.-P. Zendri, Fan Zhang, L. Zhang, M. Zhang, Y. Zhang,
C. Zhao, M. Zhou, X. J. Zhu, M. E. Zucker, S. E. Zuraw, J. Zweizig, LIGO
Scientific Collaboration and Virgo Scientific Collaboration | A search of the Orion spur for continuous gravitational waves using a
"loosely coherent" algorithm on data from LIGO interferometers | Fixed minor typo - duplicate name in the author list | Phys. Rev. D 93, 042006 (2016) | 10.1103/PhysRevD.93.042006 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We report results of a wideband search for periodic gravitational waves from
isolated neutron stars within the Orion spur towards both the inner and outer
regions of our Galaxy. As gravitational waves interact very weakly with matter,
the search is unimpeded by dust and concentrations of stars. One search disk
(A) is $6.87^\circ$ in diameter and centered on
$20^\textrm{h}10^\textrm{m}54.71^\textrm{s}+33^\circ33'25.29"$, and the other
(B) is $7.45^\circ$ in diameter and centered on
$8^\textrm{h}35^\textrm{m}20.61^\textrm{s}-46^\circ49'25.151"$. We explored the
frequency range of 50-1500 Hz and frequency derivative from $0$ to $-5\times
10^{-9}$ Hz/s. A multi-stage, loosely coherent search program allowed probing
more deeply than before in these two regions, while increasing coherence length
with every stage.
Rigorous followup parameters have winnowed initial coincidence set to only 70
candidates, to be examined manually. None of those 70 candidates proved to be
consistent with an isolated gravitational wave emitter, and 95% confidence
level upper limits were placed on continuous-wave strain amplitudes. Near $169$
Hz we achieve our lowest 95% CL upper limit on worst-case linearly polarized
strain amplitude $h_0$ of $6.3\times 10^{-25}$, while at the high end of our
frequency range we achieve a worst-case upper limit of $3.4\times 10^{-24}$ for
all polarizations and sky locations.
| [
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"version": "v1"
},
{
"created": "Wed, 14 Oct 2015 23:47:04 GMT",
"version": "v2"
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[
"Aasi",
"J.",
"",
"Ski"
],
[
"Abbott",
"B. P.",
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],
[
"Abbott",
"R.",
"",
"Ski"
],
[
"Abbott",
"T. D.",
"",
"Ski"
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[
"Abernathy",
"M. R.",
"",
"Ski"
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[
"Acernese",
"F.",
"",
"Ski"
],
[
"Ackley",
"K.",
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"Ski"
],
[
"Adams",
"C.",
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"Ski"
],
[
"Adams",
"T.",
"",
"Ski"
],
[
"Addesso",
"P.",
"",
"Ski"
],
[
"Adhikari",
"R. X.",
"",
"Ski"
],
[
"Adya",
"V. B.",
"",
"Ski"
],
[
"Affeldt",
"C.",
"",
"Ski"
],
[
"Agathos",
"M.",
"",
"Ski"
],
[
"Agatsuma",
"K.",
"",
"Ski"
],
[
"Aggarwal",
"N.",
"",
"Ski"
],
[
"Aguiar",
"O. D.",
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"Ski"
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[
"Ain",
"A.",
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"Ski"
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[
"Ajith",
"P.",
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"Ski"
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[
"Allen",
"B.",
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"Ski"
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[
"Allocca",
"A.",
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[
"Amariutei",
"D. V.",
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[
"Andersen",
"M.",
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],
[
"Anderson",
"S. B.",
"",
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[
"Anderson",
"W. G.",
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[
"Arai",
"K.",
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[
"Araya",
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[
"Arceneaux",
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[
"Areeda",
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[
"Arnaud",
"N.",
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[
"Ashton",
"G.",
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[
"Aston",
"S. M.",
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[
"Astone",
"P.",
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"Ski"
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[
"Aufmuth",
"P.",
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"Ski"
],
[
"Aulbert",
"C.",
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"Ski"
],
[
"Babak",
"S.",
"",
"Ski"
],
[
"Baker",
"P. T.",
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"Ski"
],
[
"Baldaccini",
"F.",
"",
"Ski"
],
[
"Ballardin",
"G.",
"",
"Ski"
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[
"Ballmer",
"S. W.",
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[
"Barayoga",
"J. C.",
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[
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[
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""
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[
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[
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[
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""
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[
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""
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[
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""
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""
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"P. J.",
""
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[
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"K.",
""
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[
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""
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[
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"A. R.",
""
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""
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[
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"IV"
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"M.",
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"L.",
""
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[
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""
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[
"Wang",
"G.",
""
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[
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""
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[
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"X.",
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"R. L.",
""
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"J.",
""
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"M.",
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[
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[
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""
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[
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[
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""
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[
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""
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[
"Whelan",
"J. T.",
""
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[
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"D. J.",
""
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[
"Whiting",
"B. F.",
""
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[
"Williams",
"K. J.",
""
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[
"Williams",
"L.",
""
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[
"Williams",
"R. D.",
""
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[
"Williamson",
"A. R.",
""
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[
"Willis",
"J. L.",
""
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[
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"B.",
""
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[
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"M. H.",
""
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[
"Winkler",
"W.",
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[
"Wipf",
"C. C.",
""
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[
"Wittel",
"H.",
""
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[
"Woan",
"G.",
""
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[
"Worden",
"J.",
""
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[
"Yablon",
"J.",
""
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[
"Yakushin",
"I.",
""
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[
"Yam",
"W.",
""
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[
"Yamamoto",
"H.",
""
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[
"Yancey",
"C. C.",
""
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[
"Yvert",
"M.",
""
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[
"Zadrożny",
"A.",
""
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[
"Zangrando",
"L.",
""
],
[
"Zanolin",
"M.",
""
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[
"Zendri",
"J. -P.",
""
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[
"Zhang",
"Fan",
""
],
[
"Zhang",
"L.",
""
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[
"Zhang",
"M.",
""
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[
"Zhang",
"Y.",
""
],
[
"Zhao",
"C.",
""
],
[
"Zhou",
"M.",
""
],
[
"Zhu",
"X. J.",
""
],
[
"Zucker",
"M. E.",
""
],
[
"Zuraw",
"S. E.",
""
],
[
"Zweizig",
"J.",
""
],
[
"Collaboration",
"LIGO Scientific",
""
],
[
"Collaboration",
"Virgo Scientific",
""
]
] | We report results of a wideband search for periodic gravitational waves from isolated neutron stars within the Orion spur towards both the inner and outer regions of our Galaxy. As gravitational waves interact very weakly with matter, the search is unimpeded by dust and concentrations of stars. One search disk (A) is $6.87^\circ$ in diameter and centered on $20^\textrm{h}10^\textrm{m}54.71^\textrm{s}+33^\circ33'25.29"$, and the other (B) is $7.45^\circ$ in diameter and centered on $8^\textrm{h}35^\textrm{m}20.61^\textrm{s}-46^\circ49'25.151"$. We explored the frequency range of 50-1500 Hz and frequency derivative from $0$ to $-5\times 10^{-9}$ Hz/s. A multi-stage, loosely coherent search program allowed probing more deeply than before in these two regions, while increasing coherence length with every stage. Rigorous followup parameters have winnowed initial coincidence set to only 70 candidates, to be examined manually. None of those 70 candidates proved to be consistent with an isolated gravitational wave emitter, and 95% confidence level upper limits were placed on continuous-wave strain amplitudes. Near $169$ Hz we achieve our lowest 95% CL upper limit on worst-case linearly polarized strain amplitude $h_0$ of $6.3\times 10^{-25}$, while at the high end of our frequency range we achieve a worst-case upper limit of $3.4\times 10^{-24}$ for all polarizations and sky locations. |
gr-qc/0209031 | Gerald Kaiser | Gerald Kaiser | Electromagnetic Wavelets as Hertzian Pulsed Beams in Complex Spacetime | 16 pages, 2 figures, "Topics in Mathematical Physics, General
Relativity and Cosmology" conference (in honor of Jerzy Plebanski)
<http://cabana.fis.cinvestav.mx/~merced/> | null | null | null | gr-qc math-ph math.CV math.MP | null | Electromagnetic wavelets are a family of 3x3 matrix fields W_z(x')
parameterized by complex spacetime points z=x+iy with y timelike. They are
translates of a \sl basic \rm wavelet W(z) holomorphic in the future-oriented
union T of the forward and backward tubes. Applied to a complex polarization
vector p (representing electric and magnetic dipole moments), W(z) gives an
anti-selfdual solution W(z)p of Maxwell's equations derived from a selfdual
Hertz potential Z(z)=-iS(z)p, where S is the \sl Synge function \rm acting as a
Whittaker-like scalar Hertz potential. Resolutions of unity exist giving
representations of sourceless electromagnetic fields as superpositions of
wavelets. With the choice of a branch cut, S(z) splits into a difference of
retarded and advanced \sl pulsed beams \rm whose limits as y\to 0 give the
propagators of the wave equation. This yields a similar splitting of the
wavelets and leads to their complete physical interpretation as EM pulsed beams
absorbed and emitted by a \sl disk source \rm D(y) representing the branch cut.
The choice of y determines the beam's orientation, collimation and duration,
giving beams as sharp and pulses as short as desired. The sources are computed
as spacetime distributions of electric and magnetic dipoles supported on D(y).
The wavelet representation of sourceless electromagnetic fields now splits into
representations with advanced and retarded sources. These representations are
the electromagnetic counterpart of relativistic coherent-state representations
previously derived for massive Klein-Gordon and Dirac particles.
| [
{
"created": "Mon, 9 Sep 2002 18:26:38 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Sep 2002 19:57:33 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Kaiser",
"Gerald",
""
]
] | Electromagnetic wavelets are a family of 3x3 matrix fields W_z(x') parameterized by complex spacetime points z=x+iy with y timelike. They are translates of a \sl basic \rm wavelet W(z) holomorphic in the future-oriented union T of the forward and backward tubes. Applied to a complex polarization vector p (representing electric and magnetic dipole moments), W(z) gives an anti-selfdual solution W(z)p of Maxwell's equations derived from a selfdual Hertz potential Z(z)=-iS(z)p, where S is the \sl Synge function \rm acting as a Whittaker-like scalar Hertz potential. Resolutions of unity exist giving representations of sourceless electromagnetic fields as superpositions of wavelets. With the choice of a branch cut, S(z) splits into a difference of retarded and advanced \sl pulsed beams \rm whose limits as y\to 0 give the propagators of the wave equation. This yields a similar splitting of the wavelets and leads to their complete physical interpretation as EM pulsed beams absorbed and emitted by a \sl disk source \rm D(y) representing the branch cut. The choice of y determines the beam's orientation, collimation and duration, giving beams as sharp and pulses as short as desired. The sources are computed as spacetime distributions of electric and magnetic dipoles supported on D(y). The wavelet representation of sourceless electromagnetic fields now splits into representations with advanced and retarded sources. These representations are the electromagnetic counterpart of relativistic coherent-state representations previously derived for massive Klein-Gordon and Dirac particles. |
gr-qc/9803026 | Janna Levin | Janna Levin, Evan Scannapieco and Joseph Silk | The topology of the universe: the biggest manifold of them all | Contribution to the Cosmology and Topology Workshop | Class.Quant.Grav. 15 (1998) 2689-2698 | 10.1088/0264-9381/15/9/015 | CfPA-98-TH-04 | gr-qc astro-ph | null | Clues as to the geometry of the universe are encoded in the cosmic background
radiation. Hot and cold spots in the primordial radiation may be randomly
distributed in an infinite universe while in a universe with compact topology
distinctive patterns can be generated. With improved vision, we could actually
see if the universe is wrapped into a hexagonal prism or a hyperbolic horn. We
discuss the search for such geometric patterns in predictive maps of the
microwave sky.
| [
{
"created": "Fri, 6 Mar 1998 01:31:24 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Levin",
"Janna",
""
],
[
"Scannapieco",
"Evan",
""
],
[
"Silk",
"Joseph",
""
]
] | Clues as to the geometry of the universe are encoded in the cosmic background radiation. Hot and cold spots in the primordial radiation may be randomly distributed in an infinite universe while in a universe with compact topology distinctive patterns can be generated. With improved vision, we could actually see if the universe is wrapped into a hexagonal prism or a hyperbolic horn. We discuss the search for such geometric patterns in predictive maps of the microwave sky. |
1301.1724 | Chikun Ding | Chikun Ding, Changqing Liu and Qian Guo | Spacetime noncommutative effect on black hole as particle accelerators | 12 pages, 6 figures, accepted for publication in the IJMPD | Int. J. Mod. Phys. D 22 1350013 (2013) | 10.1142/S0218271813500132 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the spacetime noncommutative effect on black hole as particle
accelerators and, find that particle falling from infinity with zero velocity
cannot collide with unbound energy when the noncommutative Kerr black hole is
exactly extremal. Our results also show that the bigger of the spinning black
hole's mass is, the higher of center of mass energy that the particles obtain.
For small and medium noncommutative Schwarzschild black hole, the collision
energy depends on the black holes' mass.
| [
{
"created": "Tue, 8 Jan 2013 23:54:42 GMT",
"version": "v1"
}
] | 2013-10-22 | [
[
"Ding",
"Chikun",
""
],
[
"Liu",
"Changqing",
""
],
[
"Guo",
"Qian",
""
]
] | We study the spacetime noncommutative effect on black hole as particle accelerators and, find that particle falling from infinity with zero velocity cannot collide with unbound energy when the noncommutative Kerr black hole is exactly extremal. Our results also show that the bigger of the spinning black hole's mass is, the higher of center of mass energy that the particles obtain. For small and medium noncommutative Schwarzschild black hole, the collision energy depends on the black holes' mass. |
2305.18214 | Stanislav Komarov | Komarov S. O., Gorbatsievich A. K. and Vereshchagin G. V | Electromagnetic field of a charge asymptotically approaching spherically
symmetric black hole | 7 pages, 2 figures | Phys. Rev. D 108 (2023) 104056 | 10.1103/PhysRevD.108.104056 | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | We consider a test charged particle falling onto a Schwarzschild black hole
and evaluate its electromagnetic field. The Regge-Wheeler equation is solved
analytically by approximating the potential barrier with Dirac delta function
and rectangular barrier. We show that for asymptotically large time measured by
a distant observer the electromagnetic field approaches the spherically
symmetric electrostatic field exponentially fast. This implies that in the
region accessible to a distant observer the initial state of separated charge
and Schwarzschild black hole becomes asymptotically indistinguishable from the
Reisnner-Nordstr\"om solution. Implications of this result for models with
plasma accretion on black holes are discussed.7 a
| [
{
"created": "Mon, 29 May 2023 17:00:18 GMT",
"version": "v1"
}
] | 2023-11-28 | [
[
"O.",
"Komarov S.",
""
],
[
"K.",
"Gorbatsievich A.",
""
],
[
"G.",
"Vereshchagin",
"V"
]
] | We consider a test charged particle falling onto a Schwarzschild black hole and evaluate its electromagnetic field. The Regge-Wheeler equation is solved analytically by approximating the potential barrier with Dirac delta function and rectangular barrier. We show that for asymptotically large time measured by a distant observer the electromagnetic field approaches the spherically symmetric electrostatic field exponentially fast. This implies that in the region accessible to a distant observer the initial state of separated charge and Schwarzschild black hole becomes asymptotically indistinguishable from the Reisnner-Nordstr\"om solution. Implications of this result for models with plasma accretion on black holes are discussed.7 a |
1702.03440 | Liudmila Fesik Ms | L. E. Fesik, Yu. V. Baryshev, V. V. Sokolov, and G. Paturel | LIGO-Virgo events localization as a test of gravitational wave
polarization state | 17 pages, 19 figures | null | null | null | gr-qc hep-ex | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The detection of the gravitational wave events GW150914, GW151226, LVT 151012
and GW170104 by the Advanced LIGO antennas has opened a new possibility for the
study of fundamental physics of gravitational interaction. We suggest a new
method for determining the polarization state of a gravitational wave, which is
independent of the nature of a GW source. For this, we calculate the allowed
sky positions of GW sources along apparent circles. This is done for each
polarization state by considering the sensitivity pattern of each antenna and
relative amplitudes of detected signals. The positions of circles are
calculated with respect to the line joining both LIGO antennas using the
observed arrival time delay of the signal between them. The apparent circles
(AC) on the sky for allowed positions of the GW sources for the GW150914,
GW151226 and LVT151012 events are parallel to the plane of the disc-like large
scale structure known as the Local Super-Cluster (LSC) of galaxies which
extends up to radius $\sim 100$ Mpc and having thickness $\sim 30$ Mpc. For the
GW170104 event, the AC is perpendicular to the LSC plane but the predicted
position of the source may also belong to the LSC plane, which is consistent
with detection of possible optical counterpart ATLAS17aeu. The next
aLIGO-aVirgo observing runs are proposed to test the possibility of clustering
the GW sources along the LSC plane.
| [
{
"created": "Sat, 11 Feb 2017 17:12:48 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Jun 2017 10:37:08 GMT",
"version": "v2"
}
] | 2017-06-29 | [
[
"Fesik",
"L. E.",
""
],
[
"Baryshev",
"Yu. V.",
""
],
[
"Sokolov",
"V. V.",
""
],
[
"Paturel",
"G.",
""
]
] | The detection of the gravitational wave events GW150914, GW151226, LVT 151012 and GW170104 by the Advanced LIGO antennas has opened a new possibility for the study of fundamental physics of gravitational interaction. We suggest a new method for determining the polarization state of a gravitational wave, which is independent of the nature of a GW source. For this, we calculate the allowed sky positions of GW sources along apparent circles. This is done for each polarization state by considering the sensitivity pattern of each antenna and relative amplitudes of detected signals. The positions of circles are calculated with respect to the line joining both LIGO antennas using the observed arrival time delay of the signal between them. The apparent circles (AC) on the sky for allowed positions of the GW sources for the GW150914, GW151226 and LVT151012 events are parallel to the plane of the disc-like large scale structure known as the Local Super-Cluster (LSC) of galaxies which extends up to radius $\sim 100$ Mpc and having thickness $\sim 30$ Mpc. For the GW170104 event, the AC is perpendicular to the LSC plane but the predicted position of the source may also belong to the LSC plane, which is consistent with detection of possible optical counterpart ATLAS17aeu. The next aLIGO-aVirgo observing runs are proposed to test the possibility of clustering the GW sources along the LSC plane. |
gr-qc/0209007 | Daniel Hofmann | Daniel Hofmann | Quantum Radiation from Black Holes | 168 pages, 14 figures, PhD thesis | null | null | null | gr-qc hep-th | null | The expectation value of the energy-momentum tensor and the Hawking flux of a
scalar field on a Schwarzschild spacetime is calculated using the zeta-function
regularisation of the heat kernel. In particular, massless particles are
considered in a spherically reduced dilaton model. The effective action is
thereby obtained by the covariant perturbation theory and the boundary
conditions are fixed by means of the energy-momentum conservation equation. In
contrast to previous approaches the expectation values are calculated directly
from the effective action which itself is derived in a straightforward manner.
| [
{
"created": "Tue, 3 Sep 2002 15:28:05 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Hofmann",
"Daniel",
""
]
] | The expectation value of the energy-momentum tensor and the Hawking flux of a scalar field on a Schwarzschild spacetime is calculated using the zeta-function regularisation of the heat kernel. In particular, massless particles are considered in a spherically reduced dilaton model. The effective action is thereby obtained by the covariant perturbation theory and the boundary conditions are fixed by means of the energy-momentum conservation equation. In contrast to previous approaches the expectation values are calculated directly from the effective action which itself is derived in a straightforward manner. |
2211.10617 | Jin Li | Bo-Rui Wang, Jin Li, He Wang | Probing the gravitational wave background from cosmic strings with
Alternative LISA-TAIJI network | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | As one of the detection targets of all gravitational wave detectors at
present, stochastic gravitational wave background (SGWB) provides us an
important way to understand the evolution of our universe. In this paper, we
explore the feasibility of detecting the SGWB generated by the loops, which
arose throughout the cosmological evolution of the cosmic string network, by
individual space detectors (e.g.~LISA, TAIJI) and joint space detectors
(LISA-TAIJI). For joint detectors, we choose three different configurations of
TAIJI (e.g.~TAIJIm, TAIJIp, TAIJIc) to form the LISA-TAIJI networks. And we
investigate the performance of them to detect the SGWB. Though comparing the
power-law sensitivity (PLS) curves of individual space detectors and joint
detectors with energy density spectrum of SGWB. We find that LISA-TAIJIc has
the best sensitivity for detecting the SGWB from cosmic string loops and is
promising to further constrains the tension of cosmic sting $G\mu=O(10^{-17})$.
| [
{
"created": "Sat, 19 Nov 2022 08:18:39 GMT",
"version": "v1"
}
] | 2022-11-22 | [
[
"Wang",
"Bo-Rui",
""
],
[
"Li",
"Jin",
""
],
[
"Wang",
"He",
""
]
] | As one of the detection targets of all gravitational wave detectors at present, stochastic gravitational wave background (SGWB) provides us an important way to understand the evolution of our universe. In this paper, we explore the feasibility of detecting the SGWB generated by the loops, which arose throughout the cosmological evolution of the cosmic string network, by individual space detectors (e.g.~LISA, TAIJI) and joint space detectors (LISA-TAIJI). For joint detectors, we choose three different configurations of TAIJI (e.g.~TAIJIm, TAIJIp, TAIJIc) to form the LISA-TAIJI networks. And we investigate the performance of them to detect the SGWB. Though comparing the power-law sensitivity (PLS) curves of individual space detectors and joint detectors with energy density spectrum of SGWB. We find that LISA-TAIJIc has the best sensitivity for detecting the SGWB from cosmic string loops and is promising to further constrains the tension of cosmic sting $G\mu=O(10^{-17})$. |
gr-qc/9904028 | Angelo Tartaglia | G. Rizzi, A. Tartaglia (Dip. Fisica del Politecnico, Turin, Italy) | On local and global measurements of the speed of light on rotating
platforms | LATEX, 8 pages, to be published in Foundations of Physics Letters | Found.Phys.Lett. 12 (1999) 179-186 | null | null | gr-qc | null | The paper shows that, conceptually and operationally, the speed of light as
measured locally in the inertial comoving frame of a point on the rim of a
rotating disk, is different from the one measured globally for a round trip
along the rim, obtained dividing the length of the rim (as measured in the
''relative space'' of the disk) by the time of flight of the light beam (as
measured by a clock at rest on the disk). As a consequence, contrary to some
recent claims, the anisotropy found in the global value, obtained by the above
procedure, in no way conflicts with the local isotropy, and the internal
consistency of the special relativity theory remains unchallenged.
| [
{
"created": "Mon, 12 Apr 1999 14:13:52 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Rizzi",
"G.",
"",
"Dip. Fisica del Politecnico, Turin, Italy"
],
[
"Tartaglia",
"A.",
"",
"Dip. Fisica del Politecnico, Turin, Italy"
]
] | The paper shows that, conceptually and operationally, the speed of light as measured locally in the inertial comoving frame of a point on the rim of a rotating disk, is different from the one measured globally for a round trip along the rim, obtained dividing the length of the rim (as measured in the ''relative space'' of the disk) by the time of flight of the light beam (as measured by a clock at rest on the disk). As a consequence, contrary to some recent claims, the anisotropy found in the global value, obtained by the above procedure, in no way conflicts with the local isotropy, and the internal consistency of the special relativity theory remains unchallenged. |
gr-qc/0402013 | Massimo Blasone Dr | M.Blasone, A.Capolupo, S.Capozziello, S.Carloni and G.Vitiello | Neutrino mixing contribution to the cosmological constant | 7 pages | Phys.Lett. A323 (2004) 182-189 | 10.1016/j.physleta.2004.02.004 | null | gr-qc | null | We show that the non-perturbative vacuum structure associated with neutrino
mixing leads to a non-zero contribution to the value of the cosmological
constant. Such a contribution comes from the specific nature of the mixing
phenomenon. Its origin is completely different from the one of the ordinary
contribution of a massive spinor field. We estimate this neutrino mixing
contribution by using the natural cut--off appearing in the quantum field
theory formalism for neutrino mixing and oscillation.
| [
{
"created": "Tue, 3 Feb 2004 17:22:40 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Blasone",
"M.",
""
],
[
"Capolupo",
"A.",
""
],
[
"Capozziello",
"S.",
""
],
[
"Carloni",
"S.",
""
],
[
"Vitiello",
"G.",
""
]
] | We show that the non-perturbative vacuum structure associated with neutrino mixing leads to a non-zero contribution to the value of the cosmological constant. Such a contribution comes from the specific nature of the mixing phenomenon. Its origin is completely different from the one of the ordinary contribution of a massive spinor field. We estimate this neutrino mixing contribution by using the natural cut--off appearing in the quantum field theory formalism for neutrino mixing and oscillation. |
1903.12072 | Tomi Koivisto | Jose Beltr\'an Jim\'enez, Lavinia Heisenberg, Tomi S. Koivisto | The canonical frame of purified gravity | 7 pages, no figures | null | 10.1142/S0218271819440127 | NORDITA 2019-030 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the recently introduced gauge theory of translations, dubbed Coincident
General Relativity, gravity is described with neither torsion nor curvature in
the spacetime affine geometry. The action of the theory enjoys an enhanced
symmetry and avoids the second derivatives that appear in the conventional
Einstein-Hilbert action. While it implies the equivalent classical dynamics,
the improved action principle can make a difference in considerations of
energetics, thermodynamics, and quantum theory. This essay reports on possible
progress in those three aspects of gravity theory. In the so-called purified
gravity, 1) energy-momentum is described locally by a conserved, symmetric
tensor, 2) the Euclidean path integral is convergent without the addition of
boundary or regulating terms and 3) it is possible to identify a canonical
frame for quantisation.
| [
{
"created": "Thu, 28 Mar 2019 15:57:28 GMT",
"version": "v1"
}
] | 2020-01-08 | [
[
"Jiménez",
"Jose Beltrán",
""
],
[
"Heisenberg",
"Lavinia",
""
],
[
"Koivisto",
"Tomi S.",
""
]
] | In the recently introduced gauge theory of translations, dubbed Coincident General Relativity, gravity is described with neither torsion nor curvature in the spacetime affine geometry. The action of the theory enjoys an enhanced symmetry and avoids the second derivatives that appear in the conventional Einstein-Hilbert action. While it implies the equivalent classical dynamics, the improved action principle can make a difference in considerations of energetics, thermodynamics, and quantum theory. This essay reports on possible progress in those three aspects of gravity theory. In the so-called purified gravity, 1) energy-momentum is described locally by a conserved, symmetric tensor, 2) the Euclidean path integral is convergent without the addition of boundary or regulating terms and 3) it is possible to identify a canonical frame for quantisation. |
1201.5423 | Guilherme de Berredo-Peixoto | G. de Berredo-Peixoto, L. Freidel, I.L. Shapiro and C.A. de Souza | Dirac fields, torsion and Barbero-Immirzi parameter in Cosmology | LaTeX file (with jcappub.sty), 16 pages, no figures. Some
formulations and discussions slightly modified, fits the version to be
published in JCAP | JCAP 06 (2012) 017 | 10.1088/1475-7516/2012/06/017 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider cosmological solution for Einstein gravity with massive fermions
with a four-fermion coupling, which emerges from the Holst action and is
related to the Barbero-Immirzi (BI) parameter. This gravitational action is an
important object of investigation in a non-perturbative formalism of quantum
gravity. We study the equation of motion for for the Dirac field within the
standard Friedman-Robertson-Walker (FRW) metric. Finally, we show the theory
with BI parameter and minimally coupling Dirac field, in the zero mass limit,
is equivalent to an additional term which looks like a perfect fluid with the
equation of state \ $p = w\rho$, with $w = 1$ which is independent of the BI
parameter. The existence of mass imposes a variable $w$, which creates either
an inflationary phase with $w=-1$, or assumes an ultra hard equation of states
$w = 1$ for very early universe. Both phases relax to a pressure less fluid $w
= 0$ for late universe (corresponding to the limit $m\to\infty$).
| [
{
"created": "Thu, 26 Jan 2012 01:31:25 GMT",
"version": "v1"
},
{
"created": "Wed, 23 May 2012 18:38:00 GMT",
"version": "v2"
}
] | 2015-06-03 | [
[
"de Berredo-Peixoto",
"G.",
""
],
[
"Freidel",
"L.",
""
],
[
"Shapiro",
"I. L.",
""
],
[
"de Souza",
"C. A.",
""
]
] | We consider cosmological solution for Einstein gravity with massive fermions with a four-fermion coupling, which emerges from the Holst action and is related to the Barbero-Immirzi (BI) parameter. This gravitational action is an important object of investigation in a non-perturbative formalism of quantum gravity. We study the equation of motion for for the Dirac field within the standard Friedman-Robertson-Walker (FRW) metric. Finally, we show the theory with BI parameter and minimally coupling Dirac field, in the zero mass limit, is equivalent to an additional term which looks like a perfect fluid with the equation of state \ $p = w\rho$, with $w = 1$ which is independent of the BI parameter. The existence of mass imposes a variable $w$, which creates either an inflationary phase with $w=-1$, or assumes an ultra hard equation of states $w = 1$ for very early universe. Both phases relax to a pressure less fluid $w = 0$ for late universe (corresponding to the limit $m\to\infty$). |
gr-qc/9409049 | Donald Marolf | Donald Marolf | Observables and a Hilbert Space for Bianchi IX | 23 pages, ReVTeX, CGPG-94/6-3, UCSBTH-94-39 | Class.Quant.Grav.12:1441-1454,1995 | 10.1088/0264-9381/12/6/010 | null | gr-qc | null | We consider a quantization of the Bianchi IX cosmological model based on
taking the constraint to be a self-adjoint operator in an auxiliary Hilbert
space. Using a WKB-style self-consistent approximation, the constraint chosen
is shown to have only continuous spectrum at zero. Nevertheless, the auxiliary
space induces an inner product on the zero-eigenvalue generalized eigenstates
such that the resulting physical Hilbert space has countably infinite
dimension. In addition, a complete set of gauge-invariant operators on the
physical space is constructed by integrating differential forms over the
spacetime. The behavior of these operators indicates that this quantization
preserves Wald's classical result that the Bianchi IX spacetimes expand to a
maximum volume and then recollapse.
| [
{
"created": "Fri, 23 Sep 1994 00:39:22 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Marolf",
"Donald",
""
]
] | We consider a quantization of the Bianchi IX cosmological model based on taking the constraint to be a self-adjoint operator in an auxiliary Hilbert space. Using a WKB-style self-consistent approximation, the constraint chosen is shown to have only continuous spectrum at zero. Nevertheless, the auxiliary space induces an inner product on the zero-eigenvalue generalized eigenstates such that the resulting physical Hilbert space has countably infinite dimension. In addition, a complete set of gauge-invariant operators on the physical space is constructed by integrating differential forms over the spacetime. The behavior of these operators indicates that this quantization preserves Wald's classical result that the Bianchi IX spacetimes expand to a maximum volume and then recollapse. |
1704.02295 | Ruward A. Mulder | Ruward A. Mulder and Dennis Dieks | Is Time Travel Too Strange to Be Possible? Determinism and Indeterminism
on Closed Timelike Curves | null | Book chapter: Nature and Ontology of Spacetime, Proceedings
(Montreal: Minkowski Institute Press, 2017) | null | null | gr-qc physics.hist-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Notoriously, the Einstein equations of general relativity have solutions in
which closed timelike curves (CTCs) occur. On these curves time loops back onto
itself, which has exotic consequences. However, in order to make time travel
stories consistent constraints have to be satisfied, which prevents seemingly
ordinary and plausible processes from occurring. This, and several other
"unphysical" features, have motivated many authors to exclude solutions with
CTCs from consideration, e.g. by conjecturing a chronology protection law. In
this contribution we shall investigate the nature of one particular class of
exotic consequences of CTCs, namely those involving unexpected cases of
indeterminism or determinism. Indeterminism arises even against the backdrop of
the usual deterministic physical theories when CTCs do not cross spacelike
hypersurfaces outside of a limited CTC-region (such hypersurfaces fail to be
Cauchy surfaces). By contrast, a certain kind of determinism appears to arise
when an indeterministic theory is applied on a CTC: things cannot be different
from what they already were. We shall argue that on further consideration both
this indeterminism and determinism on CTCs turn out to possess analogues in
other, familiar areas of physics. CTC-indeterminism is close to the
epistemological indeterminism we know from statistical physics, while the
"fixedness" typical of CTC-determinism is pervasive in physics. CTC-determinism
and CTC-indeterminism therefore do not provide incontrovertible grounds for
rejecting CTCs as conceptually inadmissible.
| [
{
"created": "Fri, 7 Apr 2017 17:11:16 GMT",
"version": "v1"
}
] | 2021-05-26 | [
[
"Mulder",
"Ruward A.",
""
],
[
"Dieks",
"Dennis",
""
]
] | Notoriously, the Einstein equations of general relativity have solutions in which closed timelike curves (CTCs) occur. On these curves time loops back onto itself, which has exotic consequences. However, in order to make time travel stories consistent constraints have to be satisfied, which prevents seemingly ordinary and plausible processes from occurring. This, and several other "unphysical" features, have motivated many authors to exclude solutions with CTCs from consideration, e.g. by conjecturing a chronology protection law. In this contribution we shall investigate the nature of one particular class of exotic consequences of CTCs, namely those involving unexpected cases of indeterminism or determinism. Indeterminism arises even against the backdrop of the usual deterministic physical theories when CTCs do not cross spacelike hypersurfaces outside of a limited CTC-region (such hypersurfaces fail to be Cauchy surfaces). By contrast, a certain kind of determinism appears to arise when an indeterministic theory is applied on a CTC: things cannot be different from what they already were. We shall argue that on further consideration both this indeterminism and determinism on CTCs turn out to possess analogues in other, familiar areas of physics. CTC-indeterminism is close to the epistemological indeterminism we know from statistical physics, while the "fixedness" typical of CTC-determinism is pervasive in physics. CTC-determinism and CTC-indeterminism therefore do not provide incontrovertible grounds for rejecting CTCs as conceptually inadmissible. |
2309.03095 | Otto Kong | Otto C.W. Kong (Nat'l Central U, Taiwan) | Equivalence Principle for Quantum Mechanics in the Heisenberg Picture | 19 pages in Revtex, no figure; proof-read version published | Class. Quantum Grav. 41 (1924) 085013 | null | NCU-HEP-k101 | gr-qc hep-th quant-ph | http://creativecommons.org/licenses/by/4.0/ | We present an exact quantum observable analog of the weak equivalence
principle for a `relativistic' quantum particle. The quantum geodesic equations
are obtained from Heisenberg equations of motion as an exact analog of a fully
covariant classical Hamiltonian evolution picture, with the proper
identification of the canonical momentum variables as $p_\mu$, rather than
$p^\mu$. We discuss the meaning of the equations in relation to projective
measurements as well as equations with solution curves as ones in the
noncommutative geometric picture of spacetime, and a plausible approach to
quantum gravity as a theory about quantum observables as physical quantities
including the notion of quantum coordinate transformation.
| [
{
"created": "Tue, 5 Sep 2023 06:39:01 GMT",
"version": "v1"
},
{
"created": "Tue, 14 May 2024 08:50:47 GMT",
"version": "v2"
}
] | 2024-05-15 | [
[
"Kong",
"Otto C. W.",
"",
"Nat'l Central U, Taiwan"
]
] | We present an exact quantum observable analog of the weak equivalence principle for a `relativistic' quantum particle. The quantum geodesic equations are obtained from Heisenberg equations of motion as an exact analog of a fully covariant classical Hamiltonian evolution picture, with the proper identification of the canonical momentum variables as $p_\mu$, rather than $p^\mu$. We discuss the meaning of the equations in relation to projective measurements as well as equations with solution curves as ones in the noncommutative geometric picture of spacetime, and a plausible approach to quantum gravity as a theory about quantum observables as physical quantities including the notion of quantum coordinate transformation. |
2004.11087 | Ming Zhang | Ming Zhang, Jie Jiang | Emissions of photons near the horizons of Kerr-Sen black holes | 12 pages, 15 captioned figures, Sec. IV added | null | 10.1103/PhysRevD.102.124012 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We investigate the escape probabilities of the photons near the horizon of
the Kerr-Sen black hole. We find that the escape probabilities of the photons
are nonzero in the event horizon limit of the extreme Kerr-Sen black hole if
the light sources are near the equator. We show that the escape probability of
a photon increases with the radial position of the light source. It is also
uncovered that the escape probability decreases if the light source with
constant radius moves from the equatorial plane to the pole. Besides, we
discover that the escape probability of a photon in the Carter frame is always
greater than the one in the locally non-rotating frame, except on the pole,
where they are equal.
| [
{
"created": "Thu, 23 Apr 2020 11:29:04 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Nov 2020 08:47:49 GMT",
"version": "v2"
}
] | 2020-12-09 | [
[
"Zhang",
"Ming",
""
],
[
"Jiang",
"Jie",
""
]
] | We investigate the escape probabilities of the photons near the horizon of the Kerr-Sen black hole. We find that the escape probabilities of the photons are nonzero in the event horizon limit of the extreme Kerr-Sen black hole if the light sources are near the equator. We show that the escape probability of a photon increases with the radial position of the light source. It is also uncovered that the escape probability decreases if the light source with constant radius moves from the equatorial plane to the pole. Besides, we discover that the escape probability of a photon in the Carter frame is always greater than the one in the locally non-rotating frame, except on the pole, where they are equal. |
1510.04022 | Stoytcho Yazadjiev | Stoytcho Yazadjiev, Boian Lazov | Classification of the static and asymptotically flat
Einstein-Maxwell-dilaton spacetimes with a photon sphere | 18 pages | Phys. Rev. D 93, 083002 (2016) | 10.1103/PhysRevD.93.083002 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the problem for the classification of static and asymptotically
flat Einstein-Maxwell-dilaton spacetimes with a photon sphere. It is first
proven that the photon spheres in Einstein-Maxwell-dilaton gravity have
constant mean and constant scalar curvature. Then we derive some relations
between the mean curvature and the physical characteristics of the photon
spheres. Using further the symmetries of the dimensionally reduced
Einstein-Maxwell-dilaton field equations we show that the lapse function, the
electrostatic potential and the dilaton field are functionally dependent in the
presence of a photon sphere. Using all this we prove the main classification
theorem by explicitly constructing all Einstein-Maxwell-dilaton solutions
possessing a non-extremal photon sphere.
| [
{
"created": "Wed, 14 Oct 2015 09:48:08 GMT",
"version": "v1"
}
] | 2016-04-13 | [
[
"Yazadjiev",
"Stoytcho",
""
],
[
"Lazov",
"Boian",
""
]
] | We consider the problem for the classification of static and asymptotically flat Einstein-Maxwell-dilaton spacetimes with a photon sphere. It is first proven that the photon spheres in Einstein-Maxwell-dilaton gravity have constant mean and constant scalar curvature. Then we derive some relations between the mean curvature and the physical characteristics of the photon spheres. Using further the symmetries of the dimensionally reduced Einstein-Maxwell-dilaton field equations we show that the lapse function, the electrostatic potential and the dilaton field are functionally dependent in the presence of a photon sphere. Using all this we prove the main classification theorem by explicitly constructing all Einstein-Maxwell-dilaton solutions possessing a non-extremal photon sphere. |
2104.06140 | Boris Latosh | Boris Latosh | On simple bootstrap in metric gravity | Some corrections are made, new references are added | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The simplest approach to bootstrap in general relativity is considered. The
approach claimed to recover the infinite perturbative series of graviton
interaction terms with a recursive coupling metric perturbations to their
energy-momentum tensor. We show that the approach provides an incorrect
expression for three-graviton interaction term. Other difficulties related with
the bootstrap approach are discussed.
| [
{
"created": "Tue, 13 Apr 2021 12:31:13 GMT",
"version": "v1"
},
{
"created": "Fri, 21 May 2021 10:59:18 GMT",
"version": "v2"
}
] | 2021-05-24 | [
[
"Latosh",
"Boris",
""
]
] | The simplest approach to bootstrap in general relativity is considered. The approach claimed to recover the infinite perturbative series of graviton interaction terms with a recursive coupling metric perturbations to their energy-momentum tensor. We show that the approach provides an incorrect expression for three-graviton interaction term. Other difficulties related with the bootstrap approach are discussed. |
2207.10965 | Krzysztof Urbanowski | K. Urbanowski | A universe born in a metastable false vacuum state needs not die | 13 pages, 7 figures; some typos corrected, comments and references
added, accepted by the European Physical Journal C. arXiv admin note: text
overlap with arXiv:2110.11957 | null | 10.1140/epjc/s10052-023-11197-4 | null | gr-qc astro-ph.HE hep-ph quant-ph | http://creativecommons.org/licenses/by/4.0/ | We try to find conditions, the fulfillment of which allows a universe born in
a metastable false vacuum state to survive and not to collapse. The conditions
found are in the form of inequalities linking the depending on time $t$
instantaneous decay rate ${\it\Gamma}(t)$ of the false vacuum state and the
Hubble parameter $H(t)$. Properties of the decay rate of a quantum metastable
states are discussed and then the possible solutions of the conditions found
are analyzed and discussed. Within the model considered it is shown that a
universe born in the metastable vacuum state has a very high chance of
surviving until very late times if the lifetime, $\tau_{0}^{F}$, of the
metastable false vacuum state is much shorter, than the duration of the
inflation process. Our analysis shows that the instability of the electroweak
vacuum does not have to result in the tragic fate of our Universe leading to
its death.
| [
{
"created": "Fri, 22 Jul 2022 09:23:20 GMT",
"version": "v1"
},
{
"created": "Sun, 31 Jul 2022 11:10:18 GMT",
"version": "v2"
},
{
"created": "Thu, 5 Jan 2023 19:41:31 GMT",
"version": "v3"
}
] | 2023-02-08 | [
[
"Urbanowski",
"K.",
""
]
] | We try to find conditions, the fulfillment of which allows a universe born in a metastable false vacuum state to survive and not to collapse. The conditions found are in the form of inequalities linking the depending on time $t$ instantaneous decay rate ${\it\Gamma}(t)$ of the false vacuum state and the Hubble parameter $H(t)$. Properties of the decay rate of a quantum metastable states are discussed and then the possible solutions of the conditions found are analyzed and discussed. Within the model considered it is shown that a universe born in the metastable vacuum state has a very high chance of surviving until very late times if the lifetime, $\tau_{0}^{F}$, of the metastable false vacuum state is much shorter, than the duration of the inflation process. Our analysis shows that the instability of the electroweak vacuum does not have to result in the tragic fate of our Universe leading to its death. |
2106.07508 | Theo Verwimp | Theo Verwimp | On Generating a Lagrangian for Higher Dimensional Gravity | 6 pages | Progress of Theoretical Physics, Vol 80, No.2 August 1988 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Lovelock Lagrangian is for even dimension D obtained from Weil
polynomials on the Lie algebra of the Lorentz group SO(1,D-1). The procedure
for generating it is related to the Weil homomorphism that converts Lie algebra
invariants into cohomology classes.
| [
{
"created": "Mon, 14 Jun 2021 15:37:51 GMT",
"version": "v1"
}
] | 2021-06-15 | [
[
"Verwimp",
"Theo",
""
]
] | The Lovelock Lagrangian is for even dimension D obtained from Weil polynomials on the Lie algebra of the Lorentz group SO(1,D-1). The procedure for generating it is related to the Weil homomorphism that converts Lie algebra invariants into cohomology classes. |
2312.01142 | Igor Fomin | I. V. Fomin, S. V. Chervon and K. A. Bolshakova | Modified inflationary models based on scalar-torsion gravity | 12 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we consider the corrections to the cosmological models based on
the teleparralel equivalent of general relativity and the scalar-torsion
gravity implying non-minimal coupling between scalar field and torsion. To
determine these corrections, we consider a power-law parameterization of the
deviations between teleparralel equivalent of general relativity and the
scalar-torsion gravity. The impact of these deviations on cosmological
dynamics, scalar field potential and parameters of cosmological perturbations
is considered for different inflationary models.
| [
{
"created": "Sat, 2 Dec 2023 14:00:05 GMT",
"version": "v1"
}
] | 2023-12-05 | [
[
"Fomin",
"I. V.",
""
],
[
"Chervon",
"S. V.",
""
],
[
"Bolshakova",
"K. A.",
""
]
] | In this work, we consider the corrections to the cosmological models based on the teleparralel equivalent of general relativity and the scalar-torsion gravity implying non-minimal coupling between scalar field and torsion. To determine these corrections, we consider a power-law parameterization of the deviations between teleparralel equivalent of general relativity and the scalar-torsion gravity. The impact of these deviations on cosmological dynamics, scalar field potential and parameters of cosmological perturbations is considered for different inflationary models. |
1507.07441 | Donato Bini | Donato Bini, Guillaume Faye, Andrea Geralico | Dynamics of extended bodies in a Kerr spacetime with spin-induced
quadrupole tensor | 27 pages, 6 figures, revtex style | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The features of equatorial motion of an extended body in Kerr spacetime are
investigated in the framework of the Mathisson-Papapetrou-Dixon model. The body
is assumed to stay at quasi-equilibrium and respond instantly to external
perturbations. Besides the mass, it is completely determined by its spin, the
multipolar expansion being truncated at the quadrupole order, with a
spin-induced quadrupole tensor. The study of the radial effective potential
allows to analytically determine the ISCO shift due to spin and the associated
frequency of the last circular orbit.
| [
{
"created": "Mon, 27 Jul 2015 15:17:22 GMT",
"version": "v1"
}
] | 2015-07-28 | [
[
"Bini",
"Donato",
""
],
[
"Faye",
"Guillaume",
""
],
[
"Geralico",
"Andrea",
""
]
] | The features of equatorial motion of an extended body in Kerr spacetime are investigated in the framework of the Mathisson-Papapetrou-Dixon model. The body is assumed to stay at quasi-equilibrium and respond instantly to external perturbations. Besides the mass, it is completely determined by its spin, the multipolar expansion being truncated at the quadrupole order, with a spin-induced quadrupole tensor. The study of the radial effective potential allows to analytically determine the ISCO shift due to spin and the associated frequency of the last circular orbit. |
gr-qc/0403067 | Kostadin Trencevski | Kostadin Trencevski | Deformation of the Planetary Orbits Caused by the Time Dependent
Gravitational Potential in the Universe | 7 pages | Gen.Rel.Grav. 37 (2005) 507-519 | 10.1007/s10714-005-0039-6 | null | gr-qc | null | In the paper are studied the deformations of the planetary orbits caused by
the time dependent gravitational potential in the universe. It is shown that
the orbits are not axially symmetric and the time dependent potential does not
cause perihelion precession. It is found a simple formula for the change of the
orbit period caused by the time dependent gravitational potential and it is
tested for two binary pulsars.
| [
{
"created": "Mon, 15 Mar 2004 20:45:57 GMT",
"version": "v1"
},
{
"created": "Thu, 20 May 2004 18:35:48 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Trencevski",
"Kostadin",
""
]
] | In the paper are studied the deformations of the planetary orbits caused by the time dependent gravitational potential in the universe. It is shown that the orbits are not axially symmetric and the time dependent potential does not cause perihelion precession. It is found a simple formula for the change of the orbit period caused by the time dependent gravitational potential and it is tested for two binary pulsars. |
gr-qc/9505020 | Bronnikov Kirill Alexandrovich | K.A.Bronnikov | ON SPHERICALLY SYMMETRIC SOLUTIONS IN D-DIMENSIONAL DILATON GRAVITY | 13 pages, latex, no figures. To appear in Grav.& Cosmology journ | Grav.Cosmol. 1 (1995) 67-78 | null | RGS-VNIIMS-001/95 | gr-qc | null | Exact static, spherically symmetric solutions to the Einstein-Abelian
gauge-dilaton equations, in $D$-dimensional gravity with a chain of $n$
Ricci-flat internal spaces are considered, with the gauge field potential
having three nonzero components: the temporal, Coulomb-like one, the one
pointing to one of the extra dimensions, and the one responsible for a radial
magnetic field. For dilaton coupling implied by string theory an
$(n+5)$-parametric family of exact solutions is obtained, while for other
dilaton couplings only $(n+3)$-parametric ones. The geometric properties and
special cases of the solutions are discussed, in particular, those when there
are horizons in the space-time. Two types of horizons are distinguished: the
conventional black-hole (BH) ones and those at which the physical section of
the space-time changes its signature ({\it T-horizons}). Two theorems are
proved, one fixing the BH and T-horizon existence conditions, the other
discarding the possibility of a regular center. Different conformal gauges are
used to characterize the system from the $D$-dimensional and 4-dimensional
viewpoints.
| [
{
"created": "Mon, 15 May 1995 07:38:41 GMT",
"version": "v1"
},
{
"created": "Wed, 17 May 1995 09:39:42 GMT",
"version": "v2"
},
{
"created": "Thu, 18 May 1995 12:24:03 GMT",
"version": "v3"
}
] | 2008-02-03 | [
[
"Bronnikov",
"K. A.",
""
]
] | Exact static, spherically symmetric solutions to the Einstein-Abelian gauge-dilaton equations, in $D$-dimensional gravity with a chain of $n$ Ricci-flat internal spaces are considered, with the gauge field potential having three nonzero components: the temporal, Coulomb-like one, the one pointing to one of the extra dimensions, and the one responsible for a radial magnetic field. For dilaton coupling implied by string theory an $(n+5)$-parametric family of exact solutions is obtained, while for other dilaton couplings only $(n+3)$-parametric ones. The geometric properties and special cases of the solutions are discussed, in particular, those when there are horizons in the space-time. Two types of horizons are distinguished: the conventional black-hole (BH) ones and those at which the physical section of the space-time changes its signature ({\it T-horizons}). Two theorems are proved, one fixing the BH and T-horizon existence conditions, the other discarding the possibility of a regular center. Different conformal gauges are used to characterize the system from the $D$-dimensional and 4-dimensional viewpoints. |
1801.01714 | Francesco Alessio | Francesco Alessio | Asymptotic Structure and Bondi-Metzner-Sachs group in General Relativity | arXiv admin note: text overlap with arXiv:1709.05134 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work the asymptotic structure of space-time and the main properties
of the Bondi-Metzner-Sachs (BMS) group, which is the asymptotic symmetry group
of asymptotically flat space-times, are analysed. Every chapter, except the
fourth, begins with a brief summary of the topics that will be dealt through it
and an introduction to the main concepts. The work can be divided into three
principal parts. The first part includes the first two chapters and is devoted
to the development of the mathematical tools that will be used throughout all
of the work. In particular we will introduce the notion of space-time and will
review the main features of what is referred to as its causal structure and the
spinor formalism, which is fundamental in the understanding of the asymptotic
properties. In the second part, which includes the third, fourth and fifth
chapters, the topological and geometrical properties of null infinity, I, and
the behaviour of the fields in its neighbourhood will be studied. Particular
attention will be paid to the peeling property. The last part is completely
dedicated to the BMS group. We will solve the asymptotic Killing equations and
find the generators of the group, discuss its group structure and Lie algebra
and eventually try to obtain the Poincar\'e group as its normal subgroup. The
work ends with a brief conclusion in which are reviewed the main modern
applications of the BMS group.
| [
{
"created": "Fri, 5 Jan 2018 11:10:32 GMT",
"version": "v1"
},
{
"created": "Sun, 20 Jan 2019 17:21:54 GMT",
"version": "v2"
}
] | 2019-01-24 | [
[
"Alessio",
"Francesco",
""
]
] | In this work the asymptotic structure of space-time and the main properties of the Bondi-Metzner-Sachs (BMS) group, which is the asymptotic symmetry group of asymptotically flat space-times, are analysed. Every chapter, except the fourth, begins with a brief summary of the topics that will be dealt through it and an introduction to the main concepts. The work can be divided into three principal parts. The first part includes the first two chapters and is devoted to the development of the mathematical tools that will be used throughout all of the work. In particular we will introduce the notion of space-time and will review the main features of what is referred to as its causal structure and the spinor formalism, which is fundamental in the understanding of the asymptotic properties. In the second part, which includes the third, fourth and fifth chapters, the topological and geometrical properties of null infinity, I, and the behaviour of the fields in its neighbourhood will be studied. Particular attention will be paid to the peeling property. The last part is completely dedicated to the BMS group. We will solve the asymptotic Killing equations and find the generators of the group, discuss its group structure and Lie algebra and eventually try to obtain the Poincar\'e group as its normal subgroup. The work ends with a brief conclusion in which are reviewed the main modern applications of the BMS group. |
1904.05727 | Khalid Saifullah | Askar Ali and Khalid Saifullah | Asymptotic magnetically charged non-singular black hole and its
thermodynamics | null | Physics Letters B 792 (2019) 276 | 10.1016/j.physletb.2019.03.041 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Some very interesting solutions of the field equations of Einstein's general
theory of relativity have been constructed in the framework of nonlinear
electrodynamics. In particular, magnetically charged black hole solutions in
the framework of exponential nonlinear electrodynamics have been obtained in
general relativity in Kruglov (2017). Using this approach a magnetically
charged non-singular black hole spacetime in the framework of exponential
electrodynamics in some modified theory of gravity has been constructed in this
letter. The metric describing asymptotic non-singular magnetized black hole is
worked out in terms of the parameter of our model. When this parameter vanishes
our solution reduces to the above mentioned black hole solution. Thermodynamics
of the resulting solution is also discussed by calculating the Hawking
temperature and heat capacity when the magnetic charge is constant. We also
find out the point where the first order phase transition induced by
temperature changes takes place. The quantum radiations from this black hole
are also discussed and the mathematical expression for the rate of energy flux
of these radiations has been obtained.
| [
{
"created": "Thu, 11 Apr 2019 14:37:47 GMT",
"version": "v1"
}
] | 2019-04-12 | [
[
"Ali",
"Askar",
""
],
[
"Saifullah",
"Khalid",
""
]
] | Some very interesting solutions of the field equations of Einstein's general theory of relativity have been constructed in the framework of nonlinear electrodynamics. In particular, magnetically charged black hole solutions in the framework of exponential nonlinear electrodynamics have been obtained in general relativity in Kruglov (2017). Using this approach a magnetically charged non-singular black hole spacetime in the framework of exponential electrodynamics in some modified theory of gravity has been constructed in this letter. The metric describing asymptotic non-singular magnetized black hole is worked out in terms of the parameter of our model. When this parameter vanishes our solution reduces to the above mentioned black hole solution. Thermodynamics of the resulting solution is also discussed by calculating the Hawking temperature and heat capacity when the magnetic charge is constant. We also find out the point where the first order phase transition induced by temperature changes takes place. The quantum radiations from this black hole are also discussed and the mathematical expression for the rate of energy flux of these radiations has been obtained. |
1311.2326 | Vladimir S. Manko | V.S. Manko, R.I. Rabad\'an, J.D. Sanabria-G\'omez | Stationary black diholes | 19 pages, 3 figures; small changes taking into account referee's
suggestions | Phys. Rev. D 89: 064049, 2014 | 10.1103/PhysRevD.89.064049 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we present and analyze the simplest physically meaningful model
for stationary black diholes - a binary configuration of counter-rotating
Kerr-Newman black holes endowed with opposite electric charges - elaborated in
a physical parametrization on the basis of one of the Ernst-Manko-Ruiz
equatorially antisymmetric solutions of the Einstein-Maxwell equations. The
model saturates the Gabach-Clement inequality for interacting black holes with
struts, and in the absence of rotation it reduces to the Emparan-Teo electric
dihole solution. The physical characteristics of each dihole constituent
satisfy identically the well-known Smarr's mass formula.
| [
{
"created": "Mon, 11 Nov 2013 01:49:45 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Nov 2013 04:28:33 GMT",
"version": "v2"
},
{
"created": "Thu, 5 Nov 2015 21:41:04 GMT",
"version": "v3"
}
] | 2015-11-09 | [
[
"Manko",
"V. S.",
""
],
[
"Rabadán",
"R. I.",
""
],
[
"Sanabria-Gómez",
"J. D.",
""
]
] | In this paper we present and analyze the simplest physically meaningful model for stationary black diholes - a binary configuration of counter-rotating Kerr-Newman black holes endowed with opposite electric charges - elaborated in a physical parametrization on the basis of one of the Ernst-Manko-Ruiz equatorially antisymmetric solutions of the Einstein-Maxwell equations. The model saturates the Gabach-Clement inequality for interacting black holes with struts, and in the absence of rotation it reduces to the Emparan-Teo electric dihole solution. The physical characteristics of each dihole constituent satisfy identically the well-known Smarr's mass formula. |
2403.16741 | Valery Zhdanov | V.I. Zhdanov, O.S. Stashko and Yu.V. Shtanov | Spherically symmetric configurations in the quadratic $f(R)$ gravity | 15 pages, 6 figures; minor corrections | Physical Review D 110, 024056 (2024) | 10.1103/PhysRevD.110.024056 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study spherically symmetric configurations of the quadratic $f(R)$ gravity
in the Einstein frame. In case of a purely gravitational system, we have
determined the global qualitative behavior of the metric and the scalaron field
for all static solutions satisfying the conditions of asymptotic flatness.
These solutions are proved to be regular everywhere except for a naked
singularity at the center; they are uniquely determined by the total mass
$\mathfrak{M}$ and the "scalar charge" $Q$ characterizing the strength of the
scalaron field at spatial infinity. The case $Q=0$ yields the Schwarzschild
solution, but an arbitrarily small $Q\ne 0$ leads to the appearance of a
central naked singularity having a significant effect on the neighboring
region, even when the space-time metric in the outer region is practically
insensitive to the scalaron field. Approximation procedures are developed to
derive asymptotic relations near the naked singularity and at spatial infinity,
and the leading terms of the solutions are presented. We investigate the linear
stability of the static solutions with respect to radial perturbations
satisfying the null Dirichlet boundary condition at the center and numerically
estimate the range of parameters corresponding to stable/unstable
configurations. In particular, the configurations with sufficiently small $Q$
turn out to be linearly unstable.
| [
{
"created": "Mon, 25 Mar 2024 13:12:50 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Apr 2024 20:00:04 GMT",
"version": "v2"
},
{
"created": "Sat, 27 Jul 2024 14:16:23 GMT",
"version": "v3"
}
] | 2024-07-30 | [
[
"Zhdanov",
"V. I.",
""
],
[
"Stashko",
"O. S.",
""
],
[
"Shtanov",
"Yu. V.",
""
]
] | We study spherically symmetric configurations of the quadratic $f(R)$ gravity in the Einstein frame. In case of a purely gravitational system, we have determined the global qualitative behavior of the metric and the scalaron field for all static solutions satisfying the conditions of asymptotic flatness. These solutions are proved to be regular everywhere except for a naked singularity at the center; they are uniquely determined by the total mass $\mathfrak{M}$ and the "scalar charge" $Q$ characterizing the strength of the scalaron field at spatial infinity. The case $Q=0$ yields the Schwarzschild solution, but an arbitrarily small $Q\ne 0$ leads to the appearance of a central naked singularity having a significant effect on the neighboring region, even when the space-time metric in the outer region is practically insensitive to the scalaron field. Approximation procedures are developed to derive asymptotic relations near the naked singularity and at spatial infinity, and the leading terms of the solutions are presented. We investigate the linear stability of the static solutions with respect to radial perturbations satisfying the null Dirichlet boundary condition at the center and numerically estimate the range of parameters corresponding to stable/unstable configurations. In particular, the configurations with sufficiently small $Q$ turn out to be linearly unstable. |
1209.3511 | John F. Donoghue | John F. Donoghue | The effective field theory treatment of quantum gravity | Presented at the Sixth International School on Field Theory and
Gravitation, Petropolis, Brazil, April 2012, to be published in the
proceedings. 22 pages, 3 figures | null | 10.1063/1.4756964 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This is a pedagogical introduction to the treatment of quantum general
relativity as an effective field theory. It starts with an overview of the
methods of effective field theory and includes an explicit example. Quantum
general relativity matches this framework and I discuss gravitational examples
as well as the limits of the effective field theory. I also discuss the
insights from effective field theory on the gravitational effects on running
couplings in the perturbative regime.
| [
{
"created": "Sun, 16 Sep 2012 18:28:38 GMT",
"version": "v1"
}
] | 2015-06-11 | [
[
"Donoghue",
"John F.",
""
]
] | This is a pedagogical introduction to the treatment of quantum general relativity as an effective field theory. It starts with an overview of the methods of effective field theory and includes an explicit example. Quantum general relativity matches this framework and I discuss gravitational examples as well as the limits of the effective field theory. I also discuss the insights from effective field theory on the gravitational effects on running couplings in the perturbative regime. |
2312.08789 | Jinbo He | Jin-Bo He | Spherical symmetric black hole based on Higher derivative gravity | To be modified | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The theory of higher derivative gravity is proposed to solve the
non-renormalizable problem in quantum gravity.In this article, We use two
numerical methods to fit another static spherically symmetric black hole
besides the Schwarzschild black hole.We obtain approximate expressions for two
numerical solutions, both of which contain a parameter that deviates from the
Schwarzschild degree.We also analyze their degree of precision and the
quasi-normal modes of the black hole.
| [
{
"created": "Thu, 14 Dec 2023 10:15:17 GMT",
"version": "v1"
},
{
"created": "Mon, 8 Jan 2024 08:47:09 GMT",
"version": "v2"
}
] | 2024-01-09 | [
[
"He",
"Jin-Bo",
""
]
] | The theory of higher derivative gravity is proposed to solve the non-renormalizable problem in quantum gravity.In this article, We use two numerical methods to fit another static spherically symmetric black hole besides the Schwarzschild black hole.We obtain approximate expressions for two numerical solutions, both of which contain a parameter that deviates from the Schwarzschild degree.We also analyze their degree of precision and the quasi-normal modes of the black hole. |
2308.00032 | Georgios K. Karananas Dr. | Georgios K. Karananas, Marco Michel, Javier Rubio | The geometry of inflationary observables: lifts, flows, equivalence
classes | 6 pages, no figures | null | null | LMU-ASC 26/23, IPARCOS-UCM-23-053 | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Eisenhart lift allows to formulate the dynamics of a scalar field in a
potential as pure geodesic motion in a curved field-space manifold involving an
additional fictitious vector field. Making use of the formalism in the context
of inflation, we show that the main inflationary observables can be expressed
in terms of the geometrical properties of a two-dimensional uplifted
field-space manifold spanned by the time derivatives of the scalar and the
temporal component of the vector. This allows to abstract from specific
potentials and models and describe inflation solely in terms of the flow of
geometric quantities. Our findings are illustrated through several inflationary
examples previously considered in the literature.
| [
{
"created": "Mon, 31 Jul 2023 18:00:02 GMT",
"version": "v1"
}
] | 2023-08-02 | [
[
"Karananas",
"Georgios K.",
""
],
[
"Michel",
"Marco",
""
],
[
"Rubio",
"Javier",
""
]
] | The Eisenhart lift allows to formulate the dynamics of a scalar field in a potential as pure geodesic motion in a curved field-space manifold involving an additional fictitious vector field. Making use of the formalism in the context of inflation, we show that the main inflationary observables can be expressed in terms of the geometrical properties of a two-dimensional uplifted field-space manifold spanned by the time derivatives of the scalar and the temporal component of the vector. This allows to abstract from specific potentials and models and describe inflation solely in terms of the flow of geometric quantities. Our findings are illustrated through several inflationary examples previously considered in the literature. |
gr-qc/9803088 | Robert Manuel Wald | Robert M. Wald | Quantum Fields in Curved Spacetimes and Semiclassical Approaches: A
Workshop Summary | 7 pages, plain LaTeX 2.09 file | null | null | null | gr-qc | null | I briefly review some of the recent progress in quantum field theory in
curved spacetime and other aspects of semiclassical gravity, as reported at the
D3 Workshop at GR15.
| [
{
"created": "Thu, 26 Mar 1998 20:54:17 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Wald",
"Robert M.",
""
]
] | I briefly review some of the recent progress in quantum field theory in curved spacetime and other aspects of semiclassical gravity, as reported at the D3 Workshop at GR15. |
2205.11746 | Paul Martens | Paul Martens, Hiroki Matsui, Shinji Mukohyama | DeWitt wave function in Ho\v{r}ava-Lifshitz cosmology with tensor
perturbation | 20 pages, 4 figures | null | 10.1088/1475-7516/2022/11/031 | YITP-22-52, IPMU22-0028 | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | We present a well-tempered DeWitt wave function, which vanishes at the
classical big-bang singularity, in Ho\v{r}ava-Lifshitz (HL) cosmology with
tensor perturbation, both analytically and numerically. In general relativity,
the DeWitt wave function is ill-behaved once the tensor perturbation is taken
into account. This is essentially because the amplitude of the perturbation
diverges at the singularity and the perturbative expansion completely breaks
down. On the other hand, in HL gravity it is known that the higher dimensional
operators required by the perturbative renormalizability render the tensor
perturbation scale-invariant and regular all the way up to the singularity. In
this paper we analytically show that in $d+1$ dimensional HL gravity the DeWitt
wave function for tensor perturbation is indeed well-defined around the
classical big-bang singularity. Also, we numerically demonstrate the
well-behaved DeWitt wave function for tensor perturbation from the big-bang to
a finite size of the Universe.
| [
{
"created": "Tue, 24 May 2022 03:20:23 GMT",
"version": "v1"
}
] | 2022-11-23 | [
[
"Martens",
"Paul",
""
],
[
"Matsui",
"Hiroki",
""
],
[
"Mukohyama",
"Shinji",
""
]
] | We present a well-tempered DeWitt wave function, which vanishes at the classical big-bang singularity, in Ho\v{r}ava-Lifshitz (HL) cosmology with tensor perturbation, both analytically and numerically. In general relativity, the DeWitt wave function is ill-behaved once the tensor perturbation is taken into account. This is essentially because the amplitude of the perturbation diverges at the singularity and the perturbative expansion completely breaks down. On the other hand, in HL gravity it is known that the higher dimensional operators required by the perturbative renormalizability render the tensor perturbation scale-invariant and regular all the way up to the singularity. In this paper we analytically show that in $d+1$ dimensional HL gravity the DeWitt wave function for tensor perturbation is indeed well-defined around the classical big-bang singularity. Also, we numerically demonstrate the well-behaved DeWitt wave function for tensor perturbation from the big-bang to a finite size of the Universe. |
1812.11181 | Michele Maggiore | Enis Belgacem, Andreas Finke, Antonia Frassino and Michele Maggiore | Testing nonlocal gravity with Lunar Laser Ranging | 46 pages, 4 figures | null | 10.1088/1475-7516/2019/02/035 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the impact of the limit on $|\dot{G}|/G$ from Lunar Laser Ranging on
"nonlocal gravity", i.e. on models of the quantum effective action of gravity
that include nonlocal terms relevant in the infrared, such as the "RR" and "RT"
models proposed by our group, and the Deser-Woodard (DW) model. We elaborate on
the analysis of Barreira et al. [1] and we confirm their findings that (under
plausible assumptions such as the absence of strong backreaction from
non-linear structures), the RR model is ruled out. We also show that the
mechanism of "perfect screening for free" suggested for the DW model actually
does not work and the DW model is also ruled out. In contrast, the RT model
passes all phenomenological consistency tests and is still a viable candidate.
| [
{
"created": "Fri, 28 Dec 2018 15:44:20 GMT",
"version": "v1"
}
] | 2019-02-27 | [
[
"Belgacem",
"Enis",
""
],
[
"Finke",
"Andreas",
""
],
[
"Frassino",
"Antonia",
""
],
[
"Maggiore",
"Michele",
""
]
] | We study the impact of the limit on $|\dot{G}|/G$ from Lunar Laser Ranging on "nonlocal gravity", i.e. on models of the quantum effective action of gravity that include nonlocal terms relevant in the infrared, such as the "RR" and "RT" models proposed by our group, and the Deser-Woodard (DW) model. We elaborate on the analysis of Barreira et al. [1] and we confirm their findings that (under plausible assumptions such as the absence of strong backreaction from non-linear structures), the RR model is ruled out. We also show that the mechanism of "perfect screening for free" suggested for the DW model actually does not work and the DW model is also ruled out. In contrast, the RT model passes all phenomenological consistency tests and is still a viable candidate. |
1312.1739 | Andrew DeBenedictis | Johan Brannlund, Andrew DeBenedictis, Alison Lauman | Topology and Volume Effects in Quantum Gravity: Wheeler-DeWitt Theory | 15 pages, 5 figures. New version has some clarifications and minor
typographical corrections. Updated version also includes a short appendix on
the geometry and topology of the sub-spaces. Matches version accepted for
publication in Classical and Quantum Gravity | Class. Quantum Grav. 31 (2014) 095011 | 10.1088/0264-9381/31/9/095011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the quantization of space-times which can possess different
topologies within a symmetry reduced version of Wheeler-DeWitt theory. The
quantum states are defined from a natural decomposition as an outer-product of
a topological state, dictating the topology of the two-surfaces of the
space-time, and a geometric state, which controls the geometry and is comprised
of solutions to the Wheeler-DeWitt constraints. Within this symmetry reduced
theory an eigenvalue equation is derived for the two-volume of spacetime, which
for spherical topology is fixed to a value of $4\pi$. However, for the other
topologies it is found that the spectrum can be \emph{discrete} and hence the
universe, if in one of these other topological states, may only possess certain
possible values for the two-volume, whereas classically all values are allowed.
We analyze this result in the context of pure gravity (black holes).
| [
{
"created": "Fri, 6 Dec 2013 00:25:29 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Mar 2014 02:52:35 GMT",
"version": "v2"
}
] | 2014-04-17 | [
[
"Brannlund",
"Johan",
""
],
[
"DeBenedictis",
"Andrew",
""
],
[
"Lauman",
"Alison",
""
]
] | We consider the quantization of space-times which can possess different topologies within a symmetry reduced version of Wheeler-DeWitt theory. The quantum states are defined from a natural decomposition as an outer-product of a topological state, dictating the topology of the two-surfaces of the space-time, and a geometric state, which controls the geometry and is comprised of solutions to the Wheeler-DeWitt constraints. Within this symmetry reduced theory an eigenvalue equation is derived for the two-volume of spacetime, which for spherical topology is fixed to a value of $4\pi$. However, for the other topologies it is found that the spectrum can be \emph{discrete} and hence the universe, if in one of these other topological states, may only possess certain possible values for the two-volume, whereas classically all values are allowed. We analyze this result in the context of pure gravity (black holes). |
1703.10791 | Jens Boos | Jens Boos and Alberto Favaro | Kerr principal null directions from Bel--Robinson and Kummer surfaces | 4 pages, 10 figures. Essay written for the Gravity Research
Foundation 2017 Awards for Essays on Gravitation | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the Kerr geometry, we calculate various surfaces of constant curvature
invariants. These extend well beyond the Kerr horizon, and we argue that they
might be of observational significance in connection with non-minimally coupled
matter fields. Moreover, we demonstrate that the principal null directions of
the Kerr geometry can be obtained by projections involving either the
Bel--Robinson or the Kummer tensor. We conjecture that this is also possible in
more general settings.
| [
{
"created": "Fri, 31 Mar 2017 08:30:36 GMT",
"version": "v1"
}
] | 2017-04-03 | [
[
"Boos",
"Jens",
""
],
[
"Favaro",
"Alberto",
""
]
] | In the Kerr geometry, we calculate various surfaces of constant curvature invariants. These extend well beyond the Kerr horizon, and we argue that they might be of observational significance in connection with non-minimally coupled matter fields. Moreover, we demonstrate that the principal null directions of the Kerr geometry can be obtained by projections involving either the Bel--Robinson or the Kummer tensor. We conjecture that this is also possible in more general settings. |
2004.02902 | Jose Natario | J\'essica Gon\c{c}alves, Jos\'e Nat\'ario | Proof of the weak cosmic censorship conjecture for several extremal
black holes | 16 pages, no figures; v2: minor changes, references added, matches
final published version | Gen. Rel. Grav. 52 (2020) 94 | 10.1007/s10714-020-02735-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show explicitly, for different types of extremal black holes, that test
fields satisfying the null energy condition at the event horizon cannot violate
the weak cosmic censorship conjecture. This is done by checking, in each case,
that the hypotheses for the general theorem in [7] are satisfied.
| [
{
"created": "Mon, 6 Apr 2020 18:00:07 GMT",
"version": "v1"
},
{
"created": "Sun, 20 Sep 2020 12:04:17 GMT",
"version": "v2"
}
] | 2020-09-22 | [
[
"Gonçalves",
"Jéssica",
""
],
[
"Natário",
"José",
""
]
] | We show explicitly, for different types of extremal black holes, that test fields satisfying the null energy condition at the event horizon cannot violate the weak cosmic censorship conjecture. This is done by checking, in each case, that the hypotheses for the general theorem in [7] are satisfied. |
1904.09864 | Yun Soo Myung | Yun Soo Myung, De-Cheng Zou | Stability of scalarized charged black holes in the
Einstein-Maxwell-Scalar theory | 23 pages, 11 figures. arXiv admin note: text overlap with
arXiv:1812.03604 | EPJC 79,641 (2019) | 10.1140/epjc/s10052-019-7176-7 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the stability of scalarized charged black holes in the
Einstein-Maxwell-Scalar (EMS) theory with quadratic coupling. These black holes
are labelled by the number of $n=0,1,2,\cdots$, where $n=0$ is called the
fundamental black hole and $n=1,2,\cdots$ denote the $n$-excited black holes.
We show that the $n=0$ black hole is stable against full perturbations, whereas
the $n=1,2$ excited black holes are unstable against the $s(l=0)$-mode scalar
perturbation. This is consistent with the EMS theory with exponential coupling,
but it contrasts to the $n=0$ scalarized black hole in the
Einstein-Gauss-Bonnet-Scalar theory with quadratic coupling. This implies that
the endpoint of unstable Reissner-Nordstr\"{o}m black holes with $\alpha>8.019$
is the $n=0$ black hole with the same $q$. Furthermore, we study the scalarized
charged black holes in the EMS theory with scalar mass $m^2_\phi=\alpha/\beta$.
| [
{
"created": "Fri, 19 Apr 2019 03:07:54 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Aug 2019 03:20:21 GMT",
"version": "v2"
}
] | 2019-08-15 | [
[
"Myung",
"Yun Soo",
""
],
[
"Zou",
"De-Cheng",
""
]
] | We analyze the stability of scalarized charged black holes in the Einstein-Maxwell-Scalar (EMS) theory with quadratic coupling. These black holes are labelled by the number of $n=0,1,2,\cdots$, where $n=0$ is called the fundamental black hole and $n=1,2,\cdots$ denote the $n$-excited black holes. We show that the $n=0$ black hole is stable against full perturbations, whereas the $n=1,2$ excited black holes are unstable against the $s(l=0)$-mode scalar perturbation. This is consistent with the EMS theory with exponential coupling, but it contrasts to the $n=0$ scalarized black hole in the Einstein-Gauss-Bonnet-Scalar theory with quadratic coupling. This implies that the endpoint of unstable Reissner-Nordstr\"{o}m black holes with $\alpha>8.019$ is the $n=0$ black hole with the same $q$. Furthermore, we study the scalarized charged black holes in the EMS theory with scalar mass $m^2_\phi=\alpha/\beta$. |
2307.05542 | Gaoping Long | Gaoping Long | Parametrization of holonomy-flux phase space in the Hamiltonian
formulation of $SO(N)$ gauge field theory with $SO(D+1)$ loop quantum gravity
as an exemplification | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | The $SO(N)$ Yang-Mills gauge theory is concerned since it can be used to
explore the new theory beyond the standard model of particle physics and the
higher dimensional loop quantum gravity. The canonical formulation and loop
quantization of $SO(N)$ Yang-Mills theory suggest a discrete $SO(N)$
holonomy-flux phase space, and the properties of the critical quantum algebras
in the loop quantized $SO(N)$ Yang-Mills theory are encoded in the symplectic
structure of this $SO(N)$ holonomy-flux phase space. With the $SO(D+1)$ loop
quantum gravity as an exemplification of loop quantized $SO(N)$ Yang-Mills
gauge theory, we introduce a new parametrization of the $SO(D+1)$ holonomy-flux
phase space in this paper. Moreover, the symplectic structure of the $SO(D+1)$
holonomy-flux phase space are analyzed in terms of the parametrization
variables. Comparing to the Poisson algebras among the $SO(D+1)$ holonomy-flux
variables, it is shown that the Poisson algebras among the parametrization
variables take a clearer formulation, i.e., the Lie algebras of $so(D+1)$ and
the Poisson algebras between angle-length pairs.
| [
{
"created": "Sat, 8 Jul 2023 19:34:21 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Jul 2023 00:10:04 GMT",
"version": "v2"
},
{
"created": "Sat, 2 Dec 2023 16:53:39 GMT",
"version": "v3"
}
] | 2023-12-05 | [
[
"Long",
"Gaoping",
""
]
] | The $SO(N)$ Yang-Mills gauge theory is concerned since it can be used to explore the new theory beyond the standard model of particle physics and the higher dimensional loop quantum gravity. The canonical formulation and loop quantization of $SO(N)$ Yang-Mills theory suggest a discrete $SO(N)$ holonomy-flux phase space, and the properties of the critical quantum algebras in the loop quantized $SO(N)$ Yang-Mills theory are encoded in the symplectic structure of this $SO(N)$ holonomy-flux phase space. With the $SO(D+1)$ loop quantum gravity as an exemplification of loop quantized $SO(N)$ Yang-Mills gauge theory, we introduce a new parametrization of the $SO(D+1)$ holonomy-flux phase space in this paper. Moreover, the symplectic structure of the $SO(D+1)$ holonomy-flux phase space are analyzed in terms of the parametrization variables. Comparing to the Poisson algebras among the $SO(D+1)$ holonomy-flux variables, it is shown that the Poisson algebras among the parametrization variables take a clearer formulation, i.e., the Lie algebras of $so(D+1)$ and the Poisson algebras between angle-length pairs. |
1106.0920 | Gordon Belot | Gordon Belot | Background-Independence | Forthcoming in General Relativity and Gravitation | null | 10.1007/s10714-011-1210-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Intuitively speaking, a classical field theory is background-independent if
the structure required to make sense of its equations is itself subject to
dynamical evolution, rather than being imposed ab initio. The aim of this paper
is to provide an explication of this intuitive notion. Background-independence
is not a not formal property of theories: the question whether a theory is
background-independent depends upon how the theory is interpreted. Under the
approach proposed here, a theory is fully background-independent relative to an
interpretation if each physical possibility corresponds to a distinct spacetime
geometry; and it falls short of full background-independence to the extent that
this condition fails.
| [
{
"created": "Sun, 5 Jun 2011 18:11:11 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Belot",
"Gordon",
""
]
] | Intuitively speaking, a classical field theory is background-independent if the structure required to make sense of its equations is itself subject to dynamical evolution, rather than being imposed ab initio. The aim of this paper is to provide an explication of this intuitive notion. Background-independence is not a not formal property of theories: the question whether a theory is background-independent depends upon how the theory is interpreted. Under the approach proposed here, a theory is fully background-independent relative to an interpretation if each physical possibility corresponds to a distinct spacetime geometry; and it falls short of full background-independence to the extent that this condition fails. |
0802.0992 | Roberto Giambo' | R. Giamb\'o, F. Giannoni, G. Magli | Genericity of blackhole formation in the gravitational collapse of
homogeneous self-interacting scalar fields | 18 pages, 4 figures | J.Math.Phys.49:042504,2008 | 10.1063/1.2907949 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gravitational collapse of a wide class of self-interacting homogeneous
scalar fields models is analyzed. The class is characterized by certain general
conditions on the scalar field potential, which, in particular, include both
asymptotically polynomial and exponential behaviors. Within this class, we show
that the generic evolution is always divergent in a finite time, and then make
use of this result to construct radiating star models of the Vaidya type. It
turns out that blackholes are generically formed in such models.
| [
{
"created": "Thu, 7 Feb 2008 14:46:34 GMT",
"version": "v1"
}
] | 2010-03-24 | [
[
"Giambó",
"R.",
""
],
[
"Giannoni",
"F.",
""
],
[
"Magli",
"G.",
""
]
] | The gravitational collapse of a wide class of self-interacting homogeneous scalar fields models is analyzed. The class is characterized by certain general conditions on the scalar field potential, which, in particular, include both asymptotically polynomial and exponential behaviors. Within this class, we show that the generic evolution is always divergent in a finite time, and then make use of this result to construct radiating star models of the Vaidya type. It turns out that blackholes are generically formed in such models. |
1812.11123 | Alan Kostelecky | Cheng-Gang Shao, Ya-Fen Chen, Yu-Jie Tan, Shan-Qing Yang, Jun Luo,
Michael Edmund Tobar, J.C. Long, E. Weisman, Alan Kostelecky | Combined Search for a Lorentz-Violating Force in Short-Range Gravity
Varying as the Inverse Sixth Power of Distance | 7 pages two-column REVTeX, accepted for publication in Physical
Review Letters | null | 10.1103/PhysRevLett.122.011102 | null | gr-qc hep-ex hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Precision measurements of the inverse-square law via experiments on
short-range gravity provide sensitive tests of Lorentz symmetry. A combined
analysis of data from experiments at the Huazhong University of Science and
Technology and Indiana University sets simultaneous limits on all 22
coefficients for Lorentz violation correcting the Newton force law as the
inverse sixth power of distance. Results are consistent with no effect at the
level of $10^{-12}$ m$^{4}$.
| [
{
"created": "Fri, 28 Dec 2018 17:36:59 GMT",
"version": "v1"
}
] | 2019-01-23 | [
[
"Shao",
"Cheng-Gang",
""
],
[
"Chen",
"Ya-Fen",
""
],
[
"Tan",
"Yu-Jie",
""
],
[
"Yang",
"Shan-Qing",
""
],
[
"Luo",
"Jun",
""
],
[
"Tobar",
"Michael Edmund",
""
],
[
"Long",
"J. C.",
""
],
[
"Weisman",
"E.",
""
],
[
"Kostelecky",
"Alan",
""
]
] | Precision measurements of the inverse-square law via experiments on short-range gravity provide sensitive tests of Lorentz symmetry. A combined analysis of data from experiments at the Huazhong University of Science and Technology and Indiana University sets simultaneous limits on all 22 coefficients for Lorentz violation correcting the Newton force law as the inverse sixth power of distance. Results are consistent with no effect at the level of $10^{-12}$ m$^{4}$. |
2402.10190 | Ryan Unger | Christoph Kehle and Ryan Unger | Extremal black hole formation as a critical phenomenon | 91 pages + references, 16 figures | null | null | null | gr-qc math-ph math.AP math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we prove that extremal black holes arise on the threshold of
gravitational collapse. More precisely, we construct smooth one-parameter
families of smooth, spherically symmetric solutions to the
Einstein-Maxwell-Vlasov system which interpolate between dispersion and
collapse and for which the critical solution is an extremal black hole.
Physically, these solutions can be understood as beams of gravitationally
self-interacting collisionless charged particles fired into Minkowski space
from past infinity. Depending on the precise value of the parameter, we show
that the Vlasov matter either disperses due to the combined effects of angular
momentum and electromagnetic repulsion, or undergoes gravitational collapse. At
the critical value of the parameter, an extremal Reissner-Nordstr\"om black
hole is formed. No naked singularities occur as the extremal threshold is
crossed. We call this critical phenomenon extremal critical collapse and the
present work constitutes the first rigorous result on the black hole formation
threshold in general relativity.
| [
{
"created": "Thu, 15 Feb 2024 18:46:40 GMT",
"version": "v1"
}
] | 2024-02-16 | [
[
"Kehle",
"Christoph",
""
],
[
"Unger",
"Ryan",
""
]
] | In this paper, we prove that extremal black holes arise on the threshold of gravitational collapse. More precisely, we construct smooth one-parameter families of smooth, spherically symmetric solutions to the Einstein-Maxwell-Vlasov system which interpolate between dispersion and collapse and for which the critical solution is an extremal black hole. Physically, these solutions can be understood as beams of gravitationally self-interacting collisionless charged particles fired into Minkowski space from past infinity. Depending on the precise value of the parameter, we show that the Vlasov matter either disperses due to the combined effects of angular momentum and electromagnetic repulsion, or undergoes gravitational collapse. At the critical value of the parameter, an extremal Reissner-Nordstr\"om black hole is formed. No naked singularities occur as the extremal threshold is crossed. We call this critical phenomenon extremal critical collapse and the present work constitutes the first rigorous result on the black hole formation threshold in general relativity. |
2112.13249 | Yuchen Huang | Yuchen Huang and Jun Tao | Thermodynamics and phase transition of BTZ black hole in a cavity | 28 pages, 8 figures, to be published in Nuclear Physics B | Nuclear Physics B 982 (2022) 115881 | 10.1016/j.nuclphysb.2022.115881 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the thermodynamics and phase transition of a BTZ
black hole in a finite space region, namely a cavity. By imposing a
temperature-fixed boundary condition on the wall of the cavity and evaluating
the Euclidean action, we derive the thermodynamic quantities and then construct
the first law of thermodynamics for a static and neutral BTZ black hole, a
rotating BTZ black hole and a charged BTZ black hole, respectively. We prove
that heat capacities of these three types of black holes are always
non-negative. Considering a grand canonical ensemble, we find that the
non-extreme rotating black hole and the charged black hole are locally
thermodynamically stable by calculating the Hessian matrix of their internal
energy. At the phase transition level, it shows that for the static and neutral
BTZ black hole, the phase transition only exists between thermal AdS3 spacetime
and the black hole. The temperature where the phase transition occurs is only
determined by the cavity radius. For rotating and charged cases, there may
exist an extra second-order phase transition between the black hole and the
black hole-cavity merger state. The phase structure of a BTZ black hole in a
cavity shows strong dissimilarities from that without the cavity.
| [
{
"created": "Sat, 25 Dec 2021 15:25:44 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Jan 2022 15:56:52 GMT",
"version": "v2"
},
{
"created": "Thu, 23 Jun 2022 08:34:48 GMT",
"version": "v3"
}
] | 2022-08-25 | [
[
"Huang",
"Yuchen",
""
],
[
"Tao",
"Jun",
""
]
] | In this paper, we study the thermodynamics and phase transition of a BTZ black hole in a finite space region, namely a cavity. By imposing a temperature-fixed boundary condition on the wall of the cavity and evaluating the Euclidean action, we derive the thermodynamic quantities and then construct the first law of thermodynamics for a static and neutral BTZ black hole, a rotating BTZ black hole and a charged BTZ black hole, respectively. We prove that heat capacities of these three types of black holes are always non-negative. Considering a grand canonical ensemble, we find that the non-extreme rotating black hole and the charged black hole are locally thermodynamically stable by calculating the Hessian matrix of their internal energy. At the phase transition level, it shows that for the static and neutral BTZ black hole, the phase transition only exists between thermal AdS3 spacetime and the black hole. The temperature where the phase transition occurs is only determined by the cavity radius. For rotating and charged cases, there may exist an extra second-order phase transition between the black hole and the black hole-cavity merger state. The phase structure of a BTZ black hole in a cavity shows strong dissimilarities from that without the cavity. |
gr-qc/0105062 | Julio Cesar Fabris | F.G. Alvarenga, J.C. Fabris, S.V.B. Goncalves and J.A.O. Marinho
(Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil) | An analysis of helium primordial nucleosynthesis with a variable
cosmological coupling | Latex file, 10 pages | Braz.J.Phys.31:546-551,2001 | 10.1590/S0103-97332001000400004 | null | gr-qc astro-ph | null | The synthesis of helium in the early Universe depends on many input
parameters, including the value of the gravitational coupling during the period
when the nucleosynthesis takes place. We compute the primordial abundance of
helium as function of the gravitational coupling, using a semi-analytical
method, in order to track the influence of $G$ in the primordial
nucleosynthesis. To be specific, we construct a cosmological model with varying
$G$, using the Brans-Dicke theory. The greater the value of $G$ at
nucleosynthesis period, the greater the abundance of helium predicted. Using
the observational data for the abundance of the primordial helium, constraints
for the time variation of $G$ are established.
| [
{
"created": "Thu, 17 May 2001 20:12:31 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Alvarenga",
"F. G.",
"",
"Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil"
],
[
"Fabris",
"J. C.",
"",
"Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil"
],
[
"Goncalves",
"S. V. B.",
"",
"Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil"
],
[
"Marinho",
"J. A. O.",
"",
"Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil"
]
] | The synthesis of helium in the early Universe depends on many input parameters, including the value of the gravitational coupling during the period when the nucleosynthesis takes place. We compute the primordial abundance of helium as function of the gravitational coupling, using a semi-analytical method, in order to track the influence of $G$ in the primordial nucleosynthesis. To be specific, we construct a cosmological model with varying $G$, using the Brans-Dicke theory. The greater the value of $G$ at nucleosynthesis period, the greater the abundance of helium predicted. Using the observational data for the abundance of the primordial helium, constraints for the time variation of $G$ are established. |
2104.14560 | Eric Linder | Eric V. Linder | Horndessence: $\Lambda$CDM Cosmology from Modified Gravity | 9 pages, 2 figures; v2 added references; v3 added appendix | null | null | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | Rather than obtaining cosmic acceleration with a scalar field potential
(quintessence) or noncanonical kinetic term (k-essence), we can do it purely
through a modified gravity braiding of the scalar and metric, i.e. the $G_3$
Horndeski action term. Such "Horndessence" allows an exact $\Lambda$CDM
cosmological expansion without any cosmological constant, and by requiring
shift symmetry we can derive the exact form of $G_3$. We find that this route
of deriving $G_3(X)$ leads to a functional form far from the usual simple
assumptions such as a power law. Horndessence without any kinetic term or
potential has the same number of parameters as $\Lambda$CDM and makes an exact
prediction for the expansion history ($\Lambda$CDM) and modified gravity cosmic
growth history; we show the viable gravitational strength $G_{\rm eff}(a)$ and
growth rate $f\sigma_8(a)$. The simplest versions of the theory fail soundness
criteria, but we learn interesting lessons along the way, in particular about
robust parametrization, and indicate possible sound extensions.
| [
{
"created": "Wed, 28 Apr 2021 18:00:03 GMT",
"version": "v1"
},
{
"created": "Mon, 10 May 2021 16:04:07 GMT",
"version": "v2"
},
{
"created": "Thu, 23 Dec 2021 18:08:26 GMT",
"version": "v3"
}
] | 2021-12-24 | [
[
"Linder",
"Eric V.",
""
]
] | Rather than obtaining cosmic acceleration with a scalar field potential (quintessence) or noncanonical kinetic term (k-essence), we can do it purely through a modified gravity braiding of the scalar and metric, i.e. the $G_3$ Horndeski action term. Such "Horndessence" allows an exact $\Lambda$CDM cosmological expansion without any cosmological constant, and by requiring shift symmetry we can derive the exact form of $G_3$. We find that this route of deriving $G_3(X)$ leads to a functional form far from the usual simple assumptions such as a power law. Horndessence without any kinetic term or potential has the same number of parameters as $\Lambda$CDM and makes an exact prediction for the expansion history ($\Lambda$CDM) and modified gravity cosmic growth history; we show the viable gravitational strength $G_{\rm eff}(a)$ and growth rate $f\sigma_8(a)$. The simplest versions of the theory fail soundness criteria, but we learn interesting lessons along the way, in particular about robust parametrization, and indicate possible sound extensions. |
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