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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1206.0179 | Monica Forte | Luis P. Chimento, M\'onica I. Forte and Mart\'in G. Richarte | Holographic dark energy linearly interacting with dark matter | March 2012. 6 pp., 6 figures. Note: To appear in the proceedings of
the CosmoSul conference, held in Rio de Janeiro, Brazil, 01-05 august of 2011 | AIP Conf. Proc. 1471, 39 (2012) | 10.1063/1.4756809 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate a spatially flat Friedmann-Robertson-Walker (FRW) cosmological
model with cold dark matter coupled to a modified holographic Ricci dark energy
through a general interaction term linear in the energy densities of dark
matter and dark energy, the total energy density and its derivative. Using the
statistical method of $\chi^2$-function for the Hubble data, we obtain
$H_0=73.6$km/sMpc, $\omega_s=-0.842$ for the asymptotic equation of state and $
z_{acc}= 0.89 $. The estimated values of $\Omega_{c0}$ which fulfill the
current observational bounds corresponds to a dark energy density varying in
the range $0.25R < \ro_x < 0.27R$.
| [
{
"created": "Fri, 1 Jun 2012 13:39:58 GMT",
"version": "v1"
}
] | 2012-10-15 | [
[
"Chimento",
"Luis P.",
""
],
[
"Forte",
"Mónica I.",
""
],
[
"Richarte",
"Martín G.",
""
]
] | We investigate a spatially flat Friedmann-Robertson-Walker (FRW) cosmological model with cold dark matter coupled to a modified holographic Ricci dark energy through a general interaction term linear in the energy densities of dark matter and dark energy, the total energy density and its derivative. Using the statistical method of $\chi^2$-function for the Hubble data, we obtain $H_0=73.6$km/sMpc, $\omega_s=-0.842$ for the asymptotic equation of state and $ z_{acc}= 0.89 $. The estimated values of $\Omega_{c0}$ which fulfill the current observational bounds corresponds to a dark energy density varying in the range $0.25R < \ro_x < 0.27R$. |
1509.02495 | Mohammed M. Khalil | Ahmed Farag Ali, Mohammed M. Khalil | Black Hole with Quantum Potential | 16 pages, 6 figures; Accepted in Nucl.Phys.B | Nucl.Phys. B909 (2016) 173-185 | 10.1016/j.nuclphysb.2016.05.005 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we investigate black hole (BH) physics in the context of
quantum corrections. These quantum corrections were introduced recently by
replacing classical geodesics with quantal (Bohmian) trajectories and hence
form a quantum Raychaudhuri equation (QRE). From the QRE, we derive a modified
Schwarzschild metric, and use that metric to investigate BH singularity and
thermodynamics. We find that these quantum corrections change the picture of
Hawking radiation greatly when the size of BH approaches the Planck scale. They
prevent the BH from total evaporation, predicting the existence of a quantum BH
remnant, which may introduce a possible resolution for the catastrophic
behavior of Hawking radiation as the BH mass approaches zero. Those corrections
also turn the spacelike singularity of the black hole to be timelike, and hence
this may ameliorate the information loss problem.
| [
{
"created": "Sun, 6 Sep 2015 11:24:38 GMT",
"version": "v1"
},
{
"created": "Sat, 24 Oct 2015 18:47:08 GMT",
"version": "v2"
},
{
"created": "Sun, 8 May 2016 08:35:57 GMT",
"version": "v3"
}
] | 2016-11-04 | [
[
"Ali",
"Ahmed Farag",
""
],
[
"Khalil",
"Mohammed M.",
""
]
] | In this work, we investigate black hole (BH) physics in the context of quantum corrections. These quantum corrections were introduced recently by replacing classical geodesics with quantal (Bohmian) trajectories and hence form a quantum Raychaudhuri equation (QRE). From the QRE, we derive a modified Schwarzschild metric, and use that metric to investigate BH singularity and thermodynamics. We find that these quantum corrections change the picture of Hawking radiation greatly when the size of BH approaches the Planck scale. They prevent the BH from total evaporation, predicting the existence of a quantum BH remnant, which may introduce a possible resolution for the catastrophic behavior of Hawking radiation as the BH mass approaches zero. Those corrections also turn the spacelike singularity of the black hole to be timelike, and hence this may ameliorate the information loss problem. |
2004.02935 | Christos Tsagas | Ameya Chavda, John D. Barrow, Christos G. Tsagas | Kinematical and dynamical aspects of ghost-matter cosmologies | Minor revision. References added. To appear in CQG | null | 10.1088/1361-6382/abad82 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the kinematical and dynamical evolution of Friedmann universes
with a mixture of non-interacting matter and a ghost-like field, in a scenario
analogous to that advocated by the Quintom model. Assuming that the
conventional matter dominates today, we find that the ghost component can bring
the future expansion and the past contraction of the model to a finite halt.
Moreover, at the moment the expansion or contraction stops, we find that the
tendency of the universe is to bounce back and re-collapse or re-expand.
Therefore, the presence of a (never dominant) ghost-field with negative density
could, in principle, drive the universe into an eternal cycle of finite
expansion, collapse, and re-expansion. Our study outlines the key features of
such a scenario and provides a simple condition for it to occur. We also derive
an autonomous set of differential equations and then employ dynamical-system
techniques to identify two families of fixed points, with and without spatial
curvature respectively. The members of the first family correspond to coasting
universes and are stable in the Lyapunov sense. Those of the latter family are
unstable repellers when their matter satisfies the strong energy condition and
Lyapunov stable in the opposite case.
| [
{
"created": "Mon, 6 Apr 2020 18:53:13 GMT",
"version": "v1"
},
{
"created": "Mon, 4 May 2020 19:15:47 GMT",
"version": "v2"
},
{
"created": "Thu, 13 Aug 2020 13:34:52 GMT",
"version": "v3"
}
] | 2020-10-28 | [
[
"Chavda",
"Ameya",
""
],
[
"Barrow",
"John D.",
""
],
[
"Tsagas",
"Christos G.",
""
]
] | We consider the kinematical and dynamical evolution of Friedmann universes with a mixture of non-interacting matter and a ghost-like field, in a scenario analogous to that advocated by the Quintom model. Assuming that the conventional matter dominates today, we find that the ghost component can bring the future expansion and the past contraction of the model to a finite halt. Moreover, at the moment the expansion or contraction stops, we find that the tendency of the universe is to bounce back and re-collapse or re-expand. Therefore, the presence of a (never dominant) ghost-field with negative density could, in principle, drive the universe into an eternal cycle of finite expansion, collapse, and re-expansion. Our study outlines the key features of such a scenario and provides a simple condition for it to occur. We also derive an autonomous set of differential equations and then employ dynamical-system techniques to identify two families of fixed points, with and without spatial curvature respectively. The members of the first family correspond to coasting universes and are stable in the Lyapunov sense. Those of the latter family are unstable repellers when their matter satisfies the strong energy condition and Lyapunov stable in the opposite case. |
1908.11418 | Matteo Breschi | Matteo Breschi, Sebastiano Bernuzzi, Francesco Zappa, Michalis
Agathos, Albino Perego, David Radice, and Alessandro Nagar | kiloHertz gravitational waves from binary neutron star remnants:
time-domain model and constraints on extreme matter | null | Phys. Rev. D 100, 104029 (2019) | 10.1103/PhysRevD.100.104029 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The remnant star of a neutron star merger is an anticipated loud source of
kiloHertz gravitational waves that conveys unique information on the equation
of state of hot matter at extreme densities. Observations of such signals are
hampered by the photon shot noise of ground-based interferometers and pose a
challenge for gravitational-wave astronomy. We develop an analytical
time-domain waveform model for postmerger signals informed by numerical
relativity simulations. The model completes effective-one-body waveforms for
quasi-circular nonspinning binaries in the kiloHertz regime. We show that a
template-based analysis can detect postmerger signals with a minimal
signal-to-noise ratios (SNR) of 8, corresponding to GW170817-like events for
third-generation interferometers. Using Bayesian model selection and the
complete inspiral-merger-postmerger waveform model it is possible to infer
whether the merger outcome is a prompt collapse to a black hole or a remnant
star. In the latter case, the radius of the maximum mass (most compact)
nonrotating neutron star can be determined to kilometer precision. We
demonstrate the feasibility of inferring the stiffness of the equation of state
at extreme densities using the quasiuniversal relations deduced from
numerical-relativity simulations.
| [
{
"created": "Thu, 29 Aug 2019 18:41:11 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Jan 2020 15:41:47 GMT",
"version": "v2"
}
] | 2020-01-22 | [
[
"Breschi",
"Matteo",
""
],
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Zappa",
"Francesco",
""
],
[
"Agathos",
"Michalis",
""
],
[
"Perego",
"Albino",
""
],
[
"Radice",
"David",
""
],
[
"Nagar",
"Alessandro",
""
... | The remnant star of a neutron star merger is an anticipated loud source of kiloHertz gravitational waves that conveys unique information on the equation of state of hot matter at extreme densities. Observations of such signals are hampered by the photon shot noise of ground-based interferometers and pose a challenge for gravitational-wave astronomy. We develop an analytical time-domain waveform model for postmerger signals informed by numerical relativity simulations. The model completes effective-one-body waveforms for quasi-circular nonspinning binaries in the kiloHertz regime. We show that a template-based analysis can detect postmerger signals with a minimal signal-to-noise ratios (SNR) of 8, corresponding to GW170817-like events for third-generation interferometers. Using Bayesian model selection and the complete inspiral-merger-postmerger waveform model it is possible to infer whether the merger outcome is a prompt collapse to a black hole or a remnant star. In the latter case, the radius of the maximum mass (most compact) nonrotating neutron star can be determined to kilometer precision. We demonstrate the feasibility of inferring the stiffness of the equation of state at extreme densities using the quasiuniversal relations deduced from numerical-relativity simulations. |
2002.10951 | Seema Satin | Seema Satin | A Fluctuation Dissipation Relation for Relativistic stars | arXiv admin note: text overlap with arXiv:1711.06859..... some flaw
in the assumption for solution of the equations has been found, which is a
non-trivial mistake, hence needs to be worked upon again with correct
assumptions, and see if this work can progress with analytical closed form
results or needs numerical work. Major modifications needed for the
mathematics worked out here | null | null | null | gr-qc astro-ph.HE astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A fluctuation-dissipation relation for perturbed configuration of a
relativistic star is obtained. The stochastic fluctuations of the classical
stress tensor comprising the matter content ( a perfect fluid) of the
relativistic star, act as the source in a classical Einstien-Langevin equation
describing the system. We discuss the linear response of these fluctuations of
the stress tensor and develop a fluctuation-dissipation relation from the first
principles. Thus a system-bath separation in terms of spacetime metric and
matter content is proposed, to study equilibrium and non equilibrium
statistical properties for a relativistic star. This is not derived from or
related to the scalar fields or quantum stress tensors and their fluctuations,
as is usually the case for semiclassical stochastic gravity.
| [
{
"created": "Sat, 22 Feb 2020 11:33:15 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Apr 2020 15:20:36 GMT",
"version": "v2"
}
] | 2020-04-02 | [
[
"Satin",
"Seema",
""
]
] | A fluctuation-dissipation relation for perturbed configuration of a relativistic star is obtained. The stochastic fluctuations of the classical stress tensor comprising the matter content ( a perfect fluid) of the relativistic star, act as the source in a classical Einstien-Langevin equation describing the system. We discuss the linear response of these fluctuations of the stress tensor and develop a fluctuation-dissipation relation from the first principles. Thus a system-bath separation in terms of spacetime metric and matter content is proposed, to study equilibrium and non equilibrium statistical properties for a relativistic star. This is not derived from or related to the scalar fields or quantum stress tensors and their fluctuations, as is usually the case for semiclassical stochastic gravity. |
1301.7595 | Vasiliy P. Neznamov | M.A. Vronsky, M.V. Gorbatenko, N.S. Kolesnikov, V.P. Neznamov, E.Yu.
Popov, I.I. Safronov | Stationary Bound States of Dirac Particles in the Schwarzschild
Gravitational Field | 24 pages, 12 figures, 2 tables | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Nondecaying bound states of elementary spin-half particles are validated and
calculated numerically for the Schwarzschild gravitational field using a
self-conjugate Hamiltonian with a flat scalar product for any value of the
gravitational coupling constant. Hilbert condition g_{00}>0 leads to a boundary
condition such that components of the vector of current density of Dirac
particles are zero near the "event horizon". At small values of the coupling
constant, the energy spectrum is close to the hydrogen-like spectrum. Based on
the results of this study, we can assume that there exists a new type of
collapsars, for which the Hawking radiation mechanism is not present. From the
standpoint of cosmology, if the value of the gravitational coupling constant is
small, alpha<<1, the new type of nonradiating relict collapsars can manifest
itself only through gravitation. Thus, they are good candidates for the role of
"dark matter" carriers. In the wide range of admissible masses, there can exist
collapsars of a new type with the masses of hypothesized WIMP particles, which
are treated as representatives of "dark matter" in numerous scenarios of the
expansion of the universe. The results of this study can lead to revisiting
some concepts of the standard cosmological model related to the evolution of
the universe and interaction of collapsars with surrounding matter.
| [
{
"created": "Thu, 31 Jan 2013 12:40:58 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Mar 2013 18:07:29 GMT",
"version": "v2"
},
{
"created": "Mon, 18 Mar 2013 08:41:44 GMT",
"version": "v3"
},
{
"created": "Wed, 10 Jul 2013 16:40:46 GMT",
"version": "v4"
}
] | 2013-07-11 | [
[
"Vronsky",
"M. A.",
""
],
[
"Gorbatenko",
"M. V.",
""
],
[
"Kolesnikov",
"N. S.",
""
],
[
"Neznamov",
"V. P.",
""
],
[
"Popov",
"E. Yu.",
""
],
[
"Safronov",
"I. I.",
""
]
] | Nondecaying bound states of elementary spin-half particles are validated and calculated numerically for the Schwarzschild gravitational field using a self-conjugate Hamiltonian with a flat scalar product for any value of the gravitational coupling constant. Hilbert condition g_{00}>0 leads to a boundary condition such that components of the vector of current density of Dirac particles are zero near the "event horizon". At small values of the coupling constant, the energy spectrum is close to the hydrogen-like spectrum. Based on the results of this study, we can assume that there exists a new type of collapsars, for which the Hawking radiation mechanism is not present. From the standpoint of cosmology, if the value of the gravitational coupling constant is small, alpha<<1, the new type of nonradiating relict collapsars can manifest itself only through gravitation. Thus, they are good candidates for the role of "dark matter" carriers. In the wide range of admissible masses, there can exist collapsars of a new type with the masses of hypothesized WIMP particles, which are treated as representatives of "dark matter" in numerous scenarios of the expansion of the universe. The results of this study can lead to revisiting some concepts of the standard cosmological model related to the evolution of the universe and interaction of collapsars with surrounding matter. |
0802.3422 | Alex Nielsen | Alex B. Nielsen | Black Holes without Event Horizons | Talk at APCTP Winter School, Daejeon, Korea, 2008. 7 pages, no
figures | J.Korean Phys.Soc.54:2576-2582,2009 | 10.3938/jkps.54.2576 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss some of the drawbacks of using event horizons to define black
holes. The reasons are both practical, physical and theoretical. We argue that
locally defined trapping horizons can remedy many of these drawbacks. We
examine of the question of whether black hole thermodynamics should be
associated with event horizons or trapping horizons. To this end we discuss
what role trapping horizons may play in black hole thermodynamics. In addition,
we show how trapping horizons may give rise to Hawking radiation and discuss
the issue of gravitational entropy.
| [
{
"created": "Sat, 23 Feb 2008 04:07:48 GMT",
"version": "v1"
}
] | 2010-11-02 | [
[
"Nielsen",
"Alex B.",
""
]
] | We discuss some of the drawbacks of using event horizons to define black holes. The reasons are both practical, physical and theoretical. We argue that locally defined trapping horizons can remedy many of these drawbacks. We examine of the question of whether black hole thermodynamics should be associated with event horizons or trapping horizons. To this end we discuss what role trapping horizons may play in black hole thermodynamics. In addition, we show how trapping horizons may give rise to Hawking radiation and discuss the issue of gravitational entropy. |
2405.14274 | Yi-Ming Hu | Lu Wang, Hong-Yu Chen, Xiangyu Lyu, En-Kun Li, Yi-Ming Hu | Window and inpainting: dealing with data gaps for TianQin | 12 pages, 5 figures, comments welcome | null | null | null | gr-qc astro-ph.GA astro-ph.IM physics.data-an | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Space-borne gravitational wave detectors like TianQin might encounter data
gaps due to factors like micro-meteoroid collisions or hardware failures. Such
glitches will cause discontinuity in the data and have been observed in the
LISA Pathfinder. The existence of such data gaps presents challenges to the
data analysis for TianQin, especially for massive black hole binary mergers,
since its signal-to-noise ratio (SNR) accumulates in a non-linear way, a gap
near the merger could lead to significant loss of SNR. It could introduce bias
in the estimate of noise properties, and furthermore the results of the
parameter estimation. In this work, using simulated TianQin data with injected
a massive black hole binary merger, we study the window function method, and
for the first time, the inpainting method to cope with the data gap, and an
iterative estimate scheme is designed to properly estimate the noise spectrum.
We find that both methods can properly estimate noise and signal parameters.
The easy-to-implement window function method can already perform well, except
that it will sacrifice some SNR due to the adoption of the window. The
inpainting method is slower, but it can minimize the impact of the data gap.
| [
{
"created": "Thu, 23 May 2024 07:51:18 GMT",
"version": "v1"
}
] | 2024-05-24 | [
[
"Wang",
"Lu",
""
],
[
"Chen",
"Hong-Yu",
""
],
[
"Lyu",
"Xiangyu",
""
],
[
"Li",
"En-Kun",
""
],
[
"Hu",
"Yi-Ming",
""
]
] | Space-borne gravitational wave detectors like TianQin might encounter data gaps due to factors like micro-meteoroid collisions or hardware failures. Such glitches will cause discontinuity in the data and have been observed in the LISA Pathfinder. The existence of such data gaps presents challenges to the data analysis for TianQin, especially for massive black hole binary mergers, since its signal-to-noise ratio (SNR) accumulates in a non-linear way, a gap near the merger could lead to significant loss of SNR. It could introduce bias in the estimate of noise properties, and furthermore the results of the parameter estimation. In this work, using simulated TianQin data with injected a massive black hole binary merger, we study the window function method, and for the first time, the inpainting method to cope with the data gap, and an iterative estimate scheme is designed to properly estimate the noise spectrum. We find that both methods can properly estimate noise and signal parameters. The easy-to-implement window function method can already perform well, except that it will sacrifice some SNR due to the adoption of the window. The inpainting method is slower, but it can minimize the impact of the data gap. |
gr-qc/9508034 | Gravity Research Group | A.Yu.Kamenshchik, I.M.Khalatnikov, A.V.Toporensky | Non-minimally coupled complex scalar field in classical and quantum
cosmology | 15 pages, LaTeX, to appear in Physics Letters B | Phys.Lett. B357 (1995) 36-42 | 10.1016/0370-2693(95)00834-8 | NSI 95/10 | gr-qc | null | We investigate the cosmological model with complex scalar self-interacting
inflaton field non-minimally coupled to gravity. The different geometries of
the Euclidean classically forbidden regions are represented. The instanton
solutions of the corresponding Euclidean equations of motion are found by
numerical calculations. These solutions give a rather non-trivial examples of
real tunnelling geometries. Possible interpretation of obtained results and
their connection with inflationary cosmology is discussed.
| [
{
"created": "Tue, 15 Aug 1995 08:22:48 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Kamenshchik",
"A. Yu.",
""
],
[
"Khalatnikov",
"I. M.",
""
],
[
"Toporensky",
"A. V.",
""
]
] | We investigate the cosmological model with complex scalar self-interacting inflaton field non-minimally coupled to gravity. The different geometries of the Euclidean classically forbidden regions are represented. The instanton solutions of the corresponding Euclidean equations of motion are found by numerical calculations. These solutions give a rather non-trivial examples of real tunnelling geometries. Possible interpretation of obtained results and their connection with inflationary cosmology is discussed. |
gr-qc/0610160 | Marc-Thierry Jaekel | Serge Reynaud (LKB - Jussieu), Marc-Thierry Jaekel (LPTENS) | Long range gravity tests and the Pioneer anomaly | 8 pages | Int.J.Mod.Phys.D16:2091-2105,2007 | 10.1142/S0218271807011656 | null | gr-qc | null | Experimental tests of gravity performed in the solar system show a good
agreement with general relativity. The latter is however challenged by the
Pioneer anomaly which might be pointing at some modification of gravity law at
ranges of the order of the size of the solar system. As this question could be
related to the puzzles of ``dark matter'' or ``dark energy'', it is important
to test it with care. There exist metric extensions of general relativity which
preserve the well verified equivalence principle while possibly changing the
metric solution in the solar system. Such extensions have the capability to
preserve compatibility with existing gravity tests while opening free space for
the Pioneer anomaly. They constitute arguments for new mission designs and new
space technologies as well as for having a new look at data of already
performed experiments.
| [
{
"created": "Tue, 31 Oct 2006 20:00:23 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Reynaud",
"Serge",
"",
"LKB - Jussieu"
],
[
"Jaekel",
"Marc-Thierry",
"",
"LPTENS"
]
] | Experimental tests of gravity performed in the solar system show a good agreement with general relativity. The latter is however challenged by the Pioneer anomaly which might be pointing at some modification of gravity law at ranges of the order of the size of the solar system. As this question could be related to the puzzles of ``dark matter'' or ``dark energy'', it is important to test it with care. There exist metric extensions of general relativity which preserve the well verified equivalence principle while possibly changing the metric solution in the solar system. Such extensions have the capability to preserve compatibility with existing gravity tests while opening free space for the Pioneer anomaly. They constitute arguments for new mission designs and new space technologies as well as for having a new look at data of already performed experiments. |
0704.2917 | Jeff Crowder | Jeff Crowder and Neil J. Cornish | Extracting galactic binary signals from the first round of Mock LISA
Data Challenges | 13 pages, 4 figures, submitted to Proceedings of GWDAW-11 (Berlin,
Dec. '06) | Class.Quant.Grav.24:S575-S586,2007 | 10.1088/0264-9381/24/19/S20 | null | gr-qc | null | We report on the performance of an end-to-end Bayesian analysis pipeline for
detecting and characterizing galactic binary signals in simulated LISA data.
Our principal analysis tool is the Blocked-Annealed Metropolis Hasting (BAM)
algorithm, which has been optimized to search for tens of thousands of
overlapping signals across the LISA band. The BAM algorithm employs Bayesian
model selection to determine the number of resolvable sources, and provides
posterior distribution functions for all the model parameters. The BAM
algorithm performed almost flawlessly on all the Round 1 Mock LISA Data
Challenge data sets, including those with many highly overlapping sources. The
only misses were later traced to a coding error that affected high frequency
sources. In addition to the BAM algorithm we also successfully tested a Genetic
Algorithm (GA), but only on data sets with isolated signals as the GA has yet
to be optimized to handle large numbers of overlapping signals.
| [
{
"created": "Mon, 23 Apr 2007 03:26:38 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Crowder",
"Jeff",
""
],
[
"Cornish",
"Neil J.",
""
]
] | We report on the performance of an end-to-end Bayesian analysis pipeline for detecting and characterizing galactic binary signals in simulated LISA data. Our principal analysis tool is the Blocked-Annealed Metropolis Hasting (BAM) algorithm, which has been optimized to search for tens of thousands of overlapping signals across the LISA band. The BAM algorithm employs Bayesian model selection to determine the number of resolvable sources, and provides posterior distribution functions for all the model parameters. The BAM algorithm performed almost flawlessly on all the Round 1 Mock LISA Data Challenge data sets, including those with many highly overlapping sources. The only misses were later traced to a coding error that affected high frequency sources. In addition to the BAM algorithm we also successfully tested a Genetic Algorithm (GA), but only on data sets with isolated signals as the GA has yet to be optimized to handle large numbers of overlapping signals. |
2012.00696 | Maria-Jose Guzman | Alexey Golovnev, Maria-Jose Guzman | Non-trivial Minkowski backgrounds in f(T) gravity | 10 pages, no figures, comments welcome; additional discussion added | Phys. Rev. D 103, 044009 (2021) | 10.1103/PhysRevD.103.044009 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | Boosted and rotated tetrad backgrounds for the Minkowski space are studied in
$f(T)$ gravity. We perform Lorentzian perturbations at first order around
non-trivial backgrounds and show that some Lorentz modes can exhibit
non-trivial dynamics and can propagate in time. This remarkable feature gives
evidence of additional mode(s) in the Lorentzian sector which have no precedent
in Lorentz-violating modified gravities, however they can cast doubts onto even
theoretical viability of these models.
| [
{
"created": "Tue, 1 Dec 2020 17:56:42 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Dec 2020 15:25:02 GMT",
"version": "v2"
},
{
"created": "Sat, 16 Jan 2021 09:29:37 GMT",
"version": "v3"
}
] | 2021-02-04 | [
[
"Golovnev",
"Alexey",
""
],
[
"Guzman",
"Maria-Jose",
""
]
] | Boosted and rotated tetrad backgrounds for the Minkowski space are studied in $f(T)$ gravity. We perform Lorentzian perturbations at first order around non-trivial backgrounds and show that some Lorentz modes can exhibit non-trivial dynamics and can propagate in time. This remarkable feature gives evidence of additional mode(s) in the Lorentzian sector which have no precedent in Lorentz-violating modified gravities, however they can cast doubts onto even theoretical viability of these models. |
1710.04015 | Klaus Liegener | Andrea Dapor and Klaus Liegener | Cosmological Coherent State Expectation Values in LQG I. Isotropic
Kinematics | 43 pages, 1 figure | Class. Quant. Grav. 35 (2018) no. 13, 135011 | 10.1088/1361-6382/aac4ba | null | gr-qc hep-lat | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This is the first paper of a series dedicated to LQG coherent states and
cosmology. The concept is based on the effective dynamics program of Loop
Quantum Cosmology, where the classical dynamics generated by the expectation
value of the Hamiltonian on semiclassical states is found to be in agreement
with the quantum evolution of such states. We ask the question of whether this
expectation value agrees with the one obtained in the full theory. The answer
is in the negative. This series of papers is dedicated to detailing the
computations that lead to that surprising result. In the current paper, we
construct the family of coherent states in LQG which represent flat ($k=0$)
Robertson-Walker spacetimes, and present the tools needed to compute
expectation values of polynomial operators in holonomy and flux on such states.
These tools will be applied to the LQG Hamiltonian operator (in Thiemann
regularization) in the second paper of the series. The third paper will present
an extension to $k\neq0$ cosmologies and a comparison with alternative
regularizations of the Hamiltonian.
| [
{
"created": "Wed, 11 Oct 2017 11:42:00 GMT",
"version": "v1"
}
] | 2019-11-14 | [
[
"Dapor",
"Andrea",
""
],
[
"Liegener",
"Klaus",
""
]
] | This is the first paper of a series dedicated to LQG coherent states and cosmology. The concept is based on the effective dynamics program of Loop Quantum Cosmology, where the classical dynamics generated by the expectation value of the Hamiltonian on semiclassical states is found to be in agreement with the quantum evolution of such states. We ask the question of whether this expectation value agrees with the one obtained in the full theory. The answer is in the negative. This series of papers is dedicated to detailing the computations that lead to that surprising result. In the current paper, we construct the family of coherent states in LQG which represent flat ($k=0$) Robertson-Walker spacetimes, and present the tools needed to compute expectation values of polynomial operators in holonomy and flux on such states. These tools will be applied to the LQG Hamiltonian operator (in Thiemann regularization) in the second paper of the series. The third paper will present an extension to $k\neq0$ cosmologies and a comparison with alternative regularizations of the Hamiltonian. |
gr-qc/0404041 | Roche Philippe | E.Buffenoir, M.Henneaux, K.Noui, Ph.Roche | Hamiltonian Analysis of Plebanski Theory | 25 pages, no figures, references added | Class.Quant.Grav.21:5203-5220,2004 | 10.1088/0264-9381/21/22/012 | null | gr-qc | null | We study the Hamiltonian formulation of Plebanski theory in both the
Euclidean and Lorentzian cases. A careful analysis of the constraints shows
that the system is non regular, i.e. the rank of the Dirac matrix is
non-constant on the non-reduced phase space. We identify the gravitational and
topological sectors which are regular sub-spaces of the non-reduced phase
space. The theory can be restricted to the regular subspace which contains the
gravitational sector. We explicitly identify first and second class constraints
in this case. We compute the determinant of the Dirac matrix and the natural
measure for the path integral of the Plebanski theory (restricted to the
gravitational sector). This measure is the analogue of the
Leutwyler-Fradkin-Vilkovisky measure of quantum gravity.
| [
{
"created": "Fri, 9 Apr 2004 10:11:17 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Jun 2004 15:45:16 GMT",
"version": "v2"
}
] | 2014-11-17 | [
[
"Buffenoir",
"E.",
""
],
[
"Henneaux",
"M.",
""
],
[
"Noui",
"K.",
""
],
[
"Roche",
"Ph.",
""
]
] | We study the Hamiltonian formulation of Plebanski theory in both the Euclidean and Lorentzian cases. A careful analysis of the constraints shows that the system is non regular, i.e. the rank of the Dirac matrix is non-constant on the non-reduced phase space. We identify the gravitational and topological sectors which are regular sub-spaces of the non-reduced phase space. The theory can be restricted to the regular subspace which contains the gravitational sector. We explicitly identify first and second class constraints in this case. We compute the determinant of the Dirac matrix and the natural measure for the path integral of the Plebanski theory (restricted to the gravitational sector). This measure is the analogue of the Leutwyler-Fradkin-Vilkovisky measure of quantum gravity. |
gr-qc/9712042 | G. Dautcourt | G. Dautcourt | Self-consistent solutions for low-frequency gravitational background
radiation | 3 pages, Latex (requires mprocl.sty). To appear in the Proceedings of
the Eighth Marcel Grossmann meeting (Jerusalem, June 22-27, 1977) | null | null | null | gr-qc | null | We study in a Brill-Hartle type of approximation the back-reaction of a
superposition of linear gravitational waves in an Einstein-de Sitter background
up to the second order in the small wave amplitudes $h_{ik}$. The wave
amplitudes are assumed to form a homogeneous and isotropic stochastic process.
No restriction for the wavelengths is assumed. The effective stress-energy
tensor $T^{e}_{\mu\nu}$ is calculated in terms of the correlation functions of
the process. We discuss in particular a situation where $T^{e}_{\mu\nu}$ is the
dominant excitation of the background metric. Apart from the Tolman radiation
universe, a solution with the scale factor of the de Sitter universe exists
with $p = -\rho$ as effective equation of state.
| [
{
"created": "Tue, 9 Dec 1997 16:09:21 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Dautcourt",
"G.",
""
]
] | We study in a Brill-Hartle type of approximation the back-reaction of a superposition of linear gravitational waves in an Einstein-de Sitter background up to the second order in the small wave amplitudes $h_{ik}$. The wave amplitudes are assumed to form a homogeneous and isotropic stochastic process. No restriction for the wavelengths is assumed. The effective stress-energy tensor $T^{e}_{\mu\nu}$ is calculated in terms of the correlation functions of the process. We discuss in particular a situation where $T^{e}_{\mu\nu}$ is the dominant excitation of the background metric. Apart from the Tolman radiation universe, a solution with the scale factor of the de Sitter universe exists with $p = -\rho$ as effective equation of state. |
gr-qc/0108024 | Gerard Clement | Gerard Clement and Sean A. Hayward | Comment on `An extreme critical space-time: echoing and black-hole
perturbations' | 3 pages | Class.Quant.Grav. 18 (2001) 4715 | 10.1088/0264-9381/18/21/401 | null | gr-qc | null | We show that the black hole perturbations of the Hayward static solution to
the massless Einstein-Klein-Gordon equations are actually gauge artifacts
resulting from the linearization of a coordinate transformation.
| [
{
"created": "Wed, 8 Aug 2001 14:45:29 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Clement",
"Gerard",
""
],
[
"Hayward",
"Sean A.",
""
]
] | We show that the black hole perturbations of the Hayward static solution to the massless Einstein-Klein-Gordon equations are actually gauge artifacts resulting from the linearization of a coordinate transformation. |
1206.1869 | Maurizio Maria D'Eliseo | Maurizio M. D'Eliseo | The relativistic precession of the orbits | Accepted for publication in Astrophysics & Space Science | null | 10.1007/s10509-012-1142-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The relativistic precession can be quickly inferred from the nonlinear polar
orbit equation without actually solving it.
| [
{
"created": "Thu, 7 Jun 2012 17:32:34 GMT",
"version": "v1"
}
] | 2015-06-05 | [
[
"D'Eliseo",
"Maurizio M.",
""
]
] | The relativistic precession can be quickly inferred from the nonlinear polar orbit equation without actually solving it. |
gr-qc/0003065 | Laszlo A. Gergely | L\'aszl\'o \'A Gergely, Mitchell McKain | The geometry of the Barbour-Bertotti theories II. The three body problem | 16 pages, 2 eps figures, to appear in Classical and Quantum Gravity | Class.Quant.Grav. 17 (2000) 1963-1978 | 10.1088/0264-9381/17/9/307 | null | gr-qc | null | We present a geometric approach to the three-body problem in the
non-relativistic context of the Barbour-Bertotti theories. The Riemannian
metric characterizing the dynamics is analyzed in detail in terms of the
relative separations. Consequences of a conformal symmetry are exploited and
the sectional curvatures of geometrically preferred surfaces are computed. The
geodesic motions are integrated. Line configurations, which lead to curvature
singularities for $N\neq 3$, are investigated. None of the independent scalars
formed from the metric and curvature tensor diverges there.
| [
{
"created": "Thu, 16 Mar 2000 09:12:27 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Gergely",
"László Á",
""
],
[
"McKain",
"Mitchell",
""
]
] | We present a geometric approach to the three-body problem in the non-relativistic context of the Barbour-Bertotti theories. The Riemannian metric characterizing the dynamics is analyzed in detail in terms of the relative separations. Consequences of a conformal symmetry are exploited and the sectional curvatures of geometrically preferred surfaces are computed. The geodesic motions are integrated. Line configurations, which lead to curvature singularities for $N\neq 3$, are investigated. None of the independent scalars formed from the metric and curvature tensor diverges there. |
1301.2430 | Gonzalo Olmo | Gonzalo J. Olmo and D. Rubiera-Garcia | Nonsingular Black Holes in Palatini Extensions of General Relativity | 3 pages, contribution to the Proceedings of the Thirteenth Marcel
Grossman Meeting on General Relativity, Astrophysics and Relativistic Field
Theories (to appear) | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss static, spherically symmetric solutions with an electric field in
a quadratic extension of general relativity formulated in the Palatini approach
(assuming that metric and connection are independent fields). Unlike the usual
metric formulation of this theory, the field equations are second-order and
ghost-free. It is found that the resulting black holes present a central core
whose area is proportional to the Planck area times the number of charges. Some
of these solutions are nonsingular. In this case, the charge-to-mass ratio
implies that the core matter density is independent of the specific amounts of
charge and mass and of order the Planck density.
| [
{
"created": "Fri, 11 Jan 2013 09:34:56 GMT",
"version": "v1"
}
] | 2013-01-14 | [
[
"Olmo",
"Gonzalo J.",
""
],
[
"Rubiera-Garcia",
"D.",
""
]
] | We discuss static, spherically symmetric solutions with an electric field in a quadratic extension of general relativity formulated in the Palatini approach (assuming that metric and connection are independent fields). Unlike the usual metric formulation of this theory, the field equations are second-order and ghost-free. It is found that the resulting black holes present a central core whose area is proportional to the Planck area times the number of charges. Some of these solutions are nonsingular. In this case, the charge-to-mass ratio implies that the core matter density is independent of the specific amounts of charge and mass and of order the Planck density. |
2207.03296 | J\'er\'emie Francfort | J\'er\'emie Francfort | Observables In Cosmology: Three Astronomical Perspectives | PhD Thesis | null | null | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | In this thesis, I present three projects I carried out during m PhD. In the
first project, I introduce Conformal Transformations and the Galaxy Number
County. I explicitly show that the Galaxy Number Counts is invariant under
Conformal Transformations, which makes it a good physical observable. In the
second project, I study how weak lensing, and in particular cosmic shear,
affects the shape of the galaxy images. I show that, if the light polarisation
is also measured, the rotation of the main axes of the elliptical galaxy shape
becomes a cosmological observable. I show how this can be used to estimate
cosmic shear and its correlation functions. In the third project, I define a
higher order (Riemann-squared and -cubed) Lagrangian Effective Theory of
Gravity. I compute the linear correction to the speed and the quasinormal
frequencies of the gravitational waves in this theory around a
Schwarzschild-like background.
| [
{
"created": "Thu, 7 Jul 2022 13:43:26 GMT",
"version": "v1"
}
] | 2022-07-08 | [
[
"Francfort",
"Jérémie",
""
]
] | In this thesis, I present three projects I carried out during m PhD. In the first project, I introduce Conformal Transformations and the Galaxy Number County. I explicitly show that the Galaxy Number Counts is invariant under Conformal Transformations, which makes it a good physical observable. In the second project, I study how weak lensing, and in particular cosmic shear, affects the shape of the galaxy images. I show that, if the light polarisation is also measured, the rotation of the main axes of the elliptical galaxy shape becomes a cosmological observable. I show how this can be used to estimate cosmic shear and its correlation functions. In the third project, I define a higher order (Riemann-squared and -cubed) Lagrangian Effective Theory of Gravity. I compute the linear correction to the speed and the quasinormal frequencies of the gravitational waves in this theory around a Schwarzschild-like background. |
2107.04342 | David Brizuela | David Brizuela, Tomasz Pawlowski | Quantum fluctuations and semiclassicality in an inflaton-driven
evolution | Expanded version of the paper accepted for publication in JCAP. We
have included a more detailed derivation of the model, some clarifications on
the presentation of the results, and several new references | JCAP 10 (2022) 080 | 10.1088/1475-7516/2022/10/080 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A semiclassical description of quantum systems is applied to probe the
dynamics of the cosmological model of an inflationary universe with quadratic
inflaton potential, described in a quantum framework of geometrodynamics. The
systematic analysis, focusing in particular on the inflationary and
post-inflationary epochs, revealed several surprising and counterintuitive
features: $(i)$ during inflation the universe rapidly spreads out in volume
which leads to significant relative variance by the end of inflation; $(ii)$
despite that, the quantum evolution can still be described to high accuracy by
semiclassical methods; $(iii)$ moreover, in the post-inflationary epoch, as the
order of included quantum corrections increases, the quantum trajectory
approaches the classical one and the description involving second-order
corrections only is actually the least accurate there. The consequence of the
latter is that the effects of the quantum variances are washed out by the
higher-order quantum corrections.
| [
{
"created": "Fri, 9 Jul 2021 10:20:54 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Oct 2022 09:56:51 GMT",
"version": "v2"
}
] | 2022-10-27 | [
[
"Brizuela",
"David",
""
],
[
"Pawlowski",
"Tomasz",
""
]
] | A semiclassical description of quantum systems is applied to probe the dynamics of the cosmological model of an inflationary universe with quadratic inflaton potential, described in a quantum framework of geometrodynamics. The systematic analysis, focusing in particular on the inflationary and post-inflationary epochs, revealed several surprising and counterintuitive features: $(i)$ during inflation the universe rapidly spreads out in volume which leads to significant relative variance by the end of inflation; $(ii)$ despite that, the quantum evolution can still be described to high accuracy by semiclassical methods; $(iii)$ moreover, in the post-inflationary epoch, as the order of included quantum corrections increases, the quantum trajectory approaches the classical one and the description involving second-order corrections only is actually the least accurate there. The consequence of the latter is that the effects of the quantum variances are washed out by the higher-order quantum corrections. |
gr-qc/0009051 | Dmitri Vassilevich | W. Kummer, D.V. Vassilevich | Hawking radiation and Hawking flux from spherical reduction | Invited Talk at Parallel Session "Black Hole Thermodynamics" of 9th
Marcel Grossmann Conference Rome, 2-8 July 2000, 6 p | null | null | null | gr-qc | null | Using heat kernel techniques we show that the relation between Hawking
temperature and radiation flux known from Einstein gravity in D dimensions can
be reproduced from the spherically reduced action. A recent controversy
regarding the D=2 anomaly for that case is discussed. The generalized effective
Polyakov action in the presence of a dilaton field is presented.
| [
{
"created": "Thu, 14 Sep 2000 15:23:42 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Kummer",
"W.",
""
],
[
"Vassilevich",
"D. V.",
""
]
] | Using heat kernel techniques we show that the relation between Hawking temperature and radiation flux known from Einstein gravity in D dimensions can be reproduced from the spherically reduced action. A recent controversy regarding the D=2 anomaly for that case is discussed. The generalized effective Polyakov action in the presence of a dilaton field is presented. |
1711.06584 | Ritabrata Biswas | Amritendu Haldar and Ritabrata Biswas | Properties of Particle Trajectory Around a Weakly Magnetized Black Hole | 13 Figures | Commun. Theor. Phys. 70 (2018) 593 | 10.1088/0253-6102/70/5/593 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider charged accelerating AdS black holes with
nonlinear electromagnetic source. The metric chosen by us is of a regular black
hole which shows regular nature at poles and a conical effect which corresponds
to a cosmic string. In such a space time construction of the Lagrangian for a
charged particle is done. Cyclic coordinates as well as the corresponding
symmetry generators, i.e., the Killing vectors are found. Conservation laws
corresponding to the symmetries are counted. Euler Lagrange equations are
found. The orbit is mainly taken to be a circular one and effective potential
is found. The minimum velocity obtained by a particle to escape from innermost
stable circular orbit is found. The values of this escape velocity is plotted
with respect to the radius of the event horizon of the central black hole for
different parametric values. The nature of the escape velocity is studied when
the central object is working with gravitational force and charge
simultaneously. Effective potential and effective force are also plotted. The
range of radius of event horizon for which the effective force turns to be
positive is found out. A pathway of future studies of accretion disc around
such black holes is made.
| [
{
"created": "Wed, 15 Nov 2017 07:30:02 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Mar 2019 01:48:09 GMT",
"version": "v2"
}
] | 2019-03-18 | [
[
"Haldar",
"Amritendu",
""
],
[
"Biswas",
"Ritabrata",
""
]
] | In this paper, we consider charged accelerating AdS black holes with nonlinear electromagnetic source. The metric chosen by us is of a regular black hole which shows regular nature at poles and a conical effect which corresponds to a cosmic string. In such a space time construction of the Lagrangian for a charged particle is done. Cyclic coordinates as well as the corresponding symmetry generators, i.e., the Killing vectors are found. Conservation laws corresponding to the symmetries are counted. Euler Lagrange equations are found. The orbit is mainly taken to be a circular one and effective potential is found. The minimum velocity obtained by a particle to escape from innermost stable circular orbit is found. The values of this escape velocity is plotted with respect to the radius of the event horizon of the central black hole for different parametric values. The nature of the escape velocity is studied when the central object is working with gravitational force and charge simultaneously. Effective potential and effective force are also plotted. The range of radius of event horizon for which the effective force turns to be positive is found out. A pathway of future studies of accretion disc around such black holes is made. |
1006.0431 | Yi Pan | Yi Pan, Alessandra Buonanno, Ryuichi Fujita, Etienne Racine, and
Hideyuki Tagoshi | Post-Newtonian factorized multipolar waveforms for spinning,
non-precessing black-hole binaries | 37 pages, 11 figures; Typos in Sec.IV Eqs.(38-42) fixed | Phys.Rev.D83:064003,2011; Phys.Rev.D87:109901(E),2013 | 10.1103/PhysRevD.83.064003 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We generalize the factorized resummation of multipolar waveforms introduced
by Damour, Iyer and Nagar to spinning black holes. For a nonspinning
test-particle spiraling a Kerr black hole in the equatorial plane, we find that
factorized multipolar amplitudes which replace the residual relativistic
amplitude f_{l m} with its l-th root, \rho_{l m} = f_{l m}^{1/l}, agree quite
well with the numerical amplitudes up to the Kerr-spin value q \leq 0.95 for
orbital velocities v \leq 0.4. The numerical amplitudes are computed solving
the Teukolsky equation with a spectral code. The agreement for prograde orbits
and large spin values of the Kerr black hole can be further improved at high
velocities by properly factoring out the lower-order post-Newtonian
contributions in \rho_{l m}. The resummation procedure results in a better and
systematic agreement between numerical and analytical amplitudes (and energy
fluxes) than standard Taylor-expanded post-Newtonian approximants. This is
particularly true for higher-order modes, such as (2,1), (3,3), (3,2), and
(4,4) for which less spin post-Newtonian terms are known. We also extend the
factorized resummation of multipolar amplitudes to generic mass-ratio,
non-precessing, spinning black holes. Lastly, in our study we employ new,
recently computed, higher-order post-Newtonian terms in several subdominant
modes, and compute explicit expressions for the half and one-and-half
post-Newtonian contributions to the odd-parity (current) and even-parity (odd)
multipoles, respectively. Those results can be used to build more accurate
templates for ground-based and space-based gravitational-wave detectors.
| [
{
"created": "Wed, 2 Jun 2010 16:01:38 GMT",
"version": "v1"
},
{
"created": "Thu, 9 May 2013 03:35:10 GMT",
"version": "v2"
}
] | 2013-05-10 | [
[
"Pan",
"Yi",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Fujita",
"Ryuichi",
""
],
[
"Racine",
"Etienne",
""
],
[
"Tagoshi",
"Hideyuki",
""
]
] | We generalize the factorized resummation of multipolar waveforms introduced by Damour, Iyer and Nagar to spinning black holes. For a nonspinning test-particle spiraling a Kerr black hole in the equatorial plane, we find that factorized multipolar amplitudes which replace the residual relativistic amplitude f_{l m} with its l-th root, \rho_{l m} = f_{l m}^{1/l}, agree quite well with the numerical amplitudes up to the Kerr-spin value q \leq 0.95 for orbital velocities v \leq 0.4. The numerical amplitudes are computed solving the Teukolsky equation with a spectral code. The agreement for prograde orbits and large spin values of the Kerr black hole can be further improved at high velocities by properly factoring out the lower-order post-Newtonian contributions in \rho_{l m}. The resummation procedure results in a better and systematic agreement between numerical and analytical amplitudes (and energy fluxes) than standard Taylor-expanded post-Newtonian approximants. This is particularly true for higher-order modes, such as (2,1), (3,3), (3,2), and (4,4) for which less spin post-Newtonian terms are known. We also extend the factorized resummation of multipolar amplitudes to generic mass-ratio, non-precessing, spinning black holes. Lastly, in our study we employ new, recently computed, higher-order post-Newtonian terms in several subdominant modes, and compute explicit expressions for the half and one-and-half post-Newtonian contributions to the odd-parity (current) and even-parity (odd) multipoles, respectively. Those results can be used to build more accurate templates for ground-based and space-based gravitational-wave detectors. |
gr-qc/0509020 | Panagiotis Labropoulos | Panagiotis G. Labropoulos, Panayiotis C. Stavrinos | A locally anisotropic geometrical model of space-time based on CMBR | 5 pages, 0 figures, 7th International Astronomy Conference of the
Hellenic Astronomical Society, curvature and connection sections decreased,
minor explanation added, fixed some typos | null | 10.1063/1.2348060 | null | gr-qc | null | We study a locally anisotropic model of General Relativity in the framework
of a more general geometrical structure than the Riemannian one. In this model
the observable anisotropy of the CMBR (WMAP) is represented by a tensor of
anisotropy and it is included in the metric structure of space-time. As well,
some interesting special cases of spaces are considered.
| [
{
"created": "Wed, 7 Sep 2005 13:43:58 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Dec 2005 22:48:26 GMT",
"version": "v2"
},
{
"created": "Fri, 17 Feb 2006 22:46:03 GMT",
"version": "v3"
}
] | 2009-11-11 | [
[
"Labropoulos",
"Panagiotis G.",
""
],
[
"Stavrinos",
"Panayiotis C.",
""
]
] | We study a locally anisotropic model of General Relativity in the framework of a more general geometrical structure than the Riemannian one. In this model the observable anisotropy of the CMBR (WMAP) is represented by a tensor of anisotropy and it is included in the metric structure of space-time. As well, some interesting special cases of spaces are considered. |
2308.09781 | Gray Reid | Gray D. Reid, Matthew W. Choptuik | Stability of Non-Minimally Coupled Topological-Defect Boson Stars | 19 pages, 24 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | As shown by Marunovic and Murkovic, non-minimal d-stars, composite structures
consisting of a boson star and a global monopole non-minimally coupled to the
general relativistic field, can have extremely high gravitational compactness.
In a previous paper we demonstrated that these ground-state stationary
solutions are sometimes additionally characterized by shells of bosonic matter
located far from the center of symmetry. In order to investigate the question
of stability posed by Marunovic and Murkovic, we investigate the stability of
several families of d-stars using both numerical simulations and linear
perturbation theory. For all families investigated, we find that the most
highly compact solutions, along with those solutions exhibiting shells of
bosonic matter, are unstable to radial perturbations and are therefore poor
candidates for astrophysically-relevant black hole mimickers or other highly
compact stable objects.
| [
{
"created": "Fri, 18 Aug 2023 19:05:32 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Dec 2023 08:07:16 GMT",
"version": "v2"
},
{
"created": "Sat, 30 Dec 2023 03:15:04 GMT",
"version": "v3"
}
] | 2024-01-02 | [
[
"Reid",
"Gray D.",
""
],
[
"Choptuik",
"Matthew W.",
""
]
] | As shown by Marunovic and Murkovic, non-minimal d-stars, composite structures consisting of a boson star and a global monopole non-minimally coupled to the general relativistic field, can have extremely high gravitational compactness. In a previous paper we demonstrated that these ground-state stationary solutions are sometimes additionally characterized by shells of bosonic matter located far from the center of symmetry. In order to investigate the question of stability posed by Marunovic and Murkovic, we investigate the stability of several families of d-stars using both numerical simulations and linear perturbation theory. For all families investigated, we find that the most highly compact solutions, along with those solutions exhibiting shells of bosonic matter, are unstable to radial perturbations and are therefore poor candidates for astrophysically-relevant black hole mimickers or other highly compact stable objects. |
1001.0288 | Jian-Yang Zhu | Li-Fang Li and Jian-Yang Zhu | Dynamical Horizon Entropy Bound Conjecture in Loop Quantum Cosmology | 4 pages, 2 figures, revised version | Commun. Theor. Phys. 58, 63 (2012) | 10.1088/0253-6102/58/1/13 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The covariant entropy bound conjecture is an important hint for the quantum
gravity, with several versions available in the literature. For cosmology,
Ashtekar and Wilson-Ewing ever show the consistence between the loop gravity
theory and one version of this conjecture. Recently, S. He and H. Zhang
proposed a version for the dynamical horizon of the universe, which validates
the entropy bound conjecture for the cosmology filled with perfect fluid in the
classical scenario when the universe is far away from the big bang singularity.
However, their conjecture breaks down near big bang region. We examine this
conjecture in the context of the loop quantum cosmology. With the example of
photon gas, this conjecture is protected by the quantum geometry effects as
expected.
| [
{
"created": "Sat, 2 Jan 2010 08:49:18 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Jun 2010 14:53:13 GMT",
"version": "v2"
}
] | 2015-05-14 | [
[
"Li",
"Li-Fang",
""
],
[
"Zhu",
"Jian-Yang",
""
]
] | The covariant entropy bound conjecture is an important hint for the quantum gravity, with several versions available in the literature. For cosmology, Ashtekar and Wilson-Ewing ever show the consistence between the loop gravity theory and one version of this conjecture. Recently, S. He and H. Zhang proposed a version for the dynamical horizon of the universe, which validates the entropy bound conjecture for the cosmology filled with perfect fluid in the classical scenario when the universe is far away from the big bang singularity. However, their conjecture breaks down near big bang region. We examine this conjecture in the context of the loop quantum cosmology. With the example of photon gas, this conjecture is protected by the quantum geometry effects as expected. |
1910.11698 | Dr. Sudhaker Upadhyay | Behnam Pourhassan and Sudhaker Upadhyay | Perturbed thermodynamics of charged black hole solution in Rastall
theory | 23 pages, 35 captioned figures, to appear in EPJ Plus | Eur. Phys. J. Plus 136, 311 (2021) | 10.1140/epjp/s13360-021-01271-9 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the thermodynamics of a charged black hole surrounded by a perfect
fluid in Rastall theory and investigate three different cases of quintessence,
dust and radiation fields. By considering thermal fluctuations, we study the
corrected thermodynamics of the system. We investigate the effects of thermal
fluctuations on the black hole stability, phase transition and critical points.
We show that the thermal fluctuations increase instability of the black hole
and may yield to the second order phase transition. We also compare our result
with uncharged cases to find the effects of the black hole charge on the
thermodynamics quantities. We find that large black holes behave like a Van der
Waals fluid, while for the small black hole where thermal fluctuations become
important, there is no Van der Waals behaviour. Finally, we briefly discuss
about geometric thermodynamics to obtain corrected scalar curvature.
| [
{
"created": "Wed, 23 Oct 2019 17:19:02 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Feb 2021 15:04:15 GMT",
"version": "v2"
}
] | 2021-03-15 | [
[
"Pourhassan",
"Behnam",
""
],
[
"Upadhyay",
"Sudhaker",
""
]
] | We study the thermodynamics of a charged black hole surrounded by a perfect fluid in Rastall theory and investigate three different cases of quintessence, dust and radiation fields. By considering thermal fluctuations, we study the corrected thermodynamics of the system. We investigate the effects of thermal fluctuations on the black hole stability, phase transition and critical points. We show that the thermal fluctuations increase instability of the black hole and may yield to the second order phase transition. We also compare our result with uncharged cases to find the effects of the black hole charge on the thermodynamics quantities. We find that large black holes behave like a Van der Waals fluid, while for the small black hole where thermal fluctuations become important, there is no Van der Waals behaviour. Finally, we briefly discuss about geometric thermodynamics to obtain corrected scalar curvature. |
gr-qc/0607121 | Catherine Meusburger | C. Meusburger | Geometrical (2+1)-gravity and the Chern-Simons formulation: Grafting,
Dehn twists, Wilson loop observables and the cosmological constant | 50 pages, 6 eps figures | Commun.Math.Phys.273:705-754,2007 | 10.1007/s00220-007-0255-x | null | gr-qc math-ph math.MP | null | We relate the geometrical and the Chern-Simons description of
(2+1)-dimensional gravity for spacetimes of topology $R\times S_g$, where $S_g$
is an oriented two-surface of genus $g>1$, for Lorentzian signature and general
cosmological constant and the Euclidean case with negative cosmological
constant. We show how the variables parametrising the phase space in the
Chern-Simons formalism are obtained from the geometrical description and how
the geometrical construction of (2+1)-spacetimes via grafting along closed,
simple geodesics gives rise to transformations on the phase space. We
demonstrate that these transformations are generated via the Poisson bracket by
one of the two canonical Wilson loop observables associated to the geodesic,
while the other acts as the Hamiltonian for infinitesimal Dehn twists. For
spacetimes with Lorentzian signature, we discuss the role of the cosmological
constant as a deformation parameter in the geometrical and the Chern-Simons
formulation of the theory. In particular, we show that the Lie algebras of the
Chern-Simons gauge groups can be identified with the (2+1)-dimensional Lorentz
algebra over a commutative ring, characterised by a formal parameter
$\Theta_\Lambda$ whose square is minus the cosmological constant. In this
framework, the Wilson loop observables that generate grafting and Dehn twists
are obtained as the real and the $\Theta_\Lambda$-component of a Wilson loop
observable with values in the ring, and the grafting transformations can be
viewed as infinitesimal Dehn twists with the parameter $\Theta_\Lambda$.
| [
{
"created": "Wed, 26 Jul 2006 17:47:41 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Meusburger",
"C.",
""
]
] | We relate the geometrical and the Chern-Simons description of (2+1)-dimensional gravity for spacetimes of topology $R\times S_g$, where $S_g$ is an oriented two-surface of genus $g>1$, for Lorentzian signature and general cosmological constant and the Euclidean case with negative cosmological constant. We show how the variables parametrising the phase space in the Chern-Simons formalism are obtained from the geometrical description and how the geometrical construction of (2+1)-spacetimes via grafting along closed, simple geodesics gives rise to transformations on the phase space. We demonstrate that these transformations are generated via the Poisson bracket by one of the two canonical Wilson loop observables associated to the geodesic, while the other acts as the Hamiltonian for infinitesimal Dehn twists. For spacetimes with Lorentzian signature, we discuss the role of the cosmological constant as a deformation parameter in the geometrical and the Chern-Simons formulation of the theory. In particular, we show that the Lie algebras of the Chern-Simons gauge groups can be identified with the (2+1)-dimensional Lorentz algebra over a commutative ring, characterised by a formal parameter $\Theta_\Lambda$ whose square is minus the cosmological constant. In this framework, the Wilson loop observables that generate grafting and Dehn twists are obtained as the real and the $\Theta_\Lambda$-component of a Wilson loop observable with values in the ring, and the grafting transformations can be viewed as infinitesimal Dehn twists with the parameter $\Theta_\Lambda$. |
1512.09003 | Sunil Maharaj | Sifiso A. Ngubelanga, Sunil D. Maharaj | Relativistic stars with polytropic equation of state | 10 pages, submitted for publication | Eur. Phys. J. Plus 130, 211 (2015) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the Einstein-Maxwell system of equations in the context of
isotropic coordinates for matter distributions with anisotropy in the presence
of an electric field. We assume a polytropic equation of state for the matter
configuration. New classes of exact solutions are generated for different
polytropic indices. The model is well behaved and we can regain masses of
several observed objects, in particular we obtain the mass of the star PSR
J1903+327.
| [
{
"created": "Wed, 30 Dec 2015 16:37:25 GMT",
"version": "v1"
}
] | 2015-12-31 | [
[
"Ngubelanga",
"Sifiso A.",
""
],
[
"Maharaj",
"Sunil D.",
""
]
] | We consider the Einstein-Maxwell system of equations in the context of isotropic coordinates for matter distributions with anisotropy in the presence of an electric field. We assume a polytropic equation of state for the matter configuration. New classes of exact solutions are generated for different polytropic indices. The model is well behaved and we can regain masses of several observed objects, in particular we obtain the mass of the star PSR J1903+327. |
gr-qc/9904044 | B. Linet | B. Linet | Electrostatics in a Schwarzschild black hole pierced by a cosmic string | Latex, 8 pages, 1 figure in latex | Class.Quant.Grav. 16 (1999) 2947-2953 | 10.1088/0264-9381/16/9/312 | null | gr-qc | null | We explicitly determine the expression of the electrostatic potential
generated by a point charge at rest in the Schwarzschild black hole pierced by
a cosmic string. We can then calculate the electrostatic self-energy. From
this, we find again the upper entropy bound for a charged object by employing
thermodynamics of the black hole.
| [
{
"created": "Mon, 19 Apr 1999 08:55:32 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Linet",
"B.",
""
]
] | We explicitly determine the expression of the electrostatic potential generated by a point charge at rest in the Schwarzschild black hole pierced by a cosmic string. We can then calculate the electrostatic self-energy. From this, we find again the upper entropy bound for a charged object by employing thermodynamics of the black hole. |
gr-qc/0311063 | Anatoli Vankov A. | Anatoli Vankov | On Problem of Mass Origin and Self-Energy Divergence in Relativistic
Mechanics and Gravitational Physics | null | null | null | null | gr-qc | null | The classical problem of self-energy divergence was studied in the framework
of Lagrangian formulation of Relativistic Mechanics. The conclusion was made
that a revision of mass-energy concept is needed for the development of
singularity-free gravitational and electromagnetic field theory. Perspectives
of the development of unified field theory are discussed.
| [
{
"created": "Thu, 20 Nov 2003 00:33:31 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Vankov",
"Anatoli",
""
]
] | The classical problem of self-energy divergence was studied in the framework of Lagrangian formulation of Relativistic Mechanics. The conclusion was made that a revision of mass-energy concept is needed for the development of singularity-free gravitational and electromagnetic field theory. Perspectives of the development of unified field theory are discussed. |
0808.2335 | Hamid Reza Sepangi | Malihe Heydari-Fard and Hamid R. Sepangi | Can local bulk effects explain the galactic dark matter? | 11 pages, no figures | JCAP 0808:018,2008 | 10.1088/1475-7516/2008/08/018 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain the virial theorem within the context of a brane-world model
without mirror symmetry or any form of junction condition. Taking a constant
curvature bulk (neglecting non-local bulk effects), the local bulk effects
generate a geometrical mass, contributing to the gravitational energy which may
be used to explain the virial mass discrepancy in clusters of galaxies. We fix
the parameter of this model in agreement with observational data.
| [
{
"created": "Mon, 18 Aug 2008 04:16:31 GMT",
"version": "v1"
}
] | 2010-10-27 | [
[
"Heydari-Fard",
"Malihe",
""
],
[
"Sepangi",
"Hamid R.",
""
]
] | We obtain the virial theorem within the context of a brane-world model without mirror symmetry or any form of junction condition. Taking a constant curvature bulk (neglecting non-local bulk effects), the local bulk effects generate a geometrical mass, contributing to the gravitational energy which may be used to explain the virial mass discrepancy in clusters of galaxies. We fix the parameter of this model in agreement with observational data. |
2009.01254 | Christopher Munna | Christopher Munna, Charles R. Evans | Eccentric-orbit extreme-mass-ratio-inspiral radiation II: 1PN correction
to leading-logarithm and subleading-logarithm flux sequences and the entire
perturbative 4PN flux | 36 pages, 1 figure | Phys. Rev. D 102, 104006 (2020) | 10.1103/PhysRevD.102.104006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a recent paper we showed that for eccentric-orbit extreme-mass-ratio
inspirals the analytic forms of the leading-logarithm energy and angular
momentum post-Newtonian (PN) flux terms (radiated to infinity) can, to
arbitrary PN order, be determined by sums over the Fourier spectrum of the
Newtonian quadrupole moment. We further showed that an essential part of the
eccentricity dependence of the related subleading-logarithm PN sequences, at
lowest order in the symmetric mass ratio $\nu$, stems as well from the
Newtonian quadrupole moment. Once that part is factored out, the remaining
eccentricity dependence is more easily determined by black hole perturbation
theory. In this paper we show how the sequences that are the 1PN corrections to
the entire leading-logarithm series, namely terms that appear at PN orders
$x^{3k+1} \log^k(x)$ and $x^{3k+5/2} \log^k(x)$ (for PN compactness parameter
$x$ and integers $k\ge 0$), at lowest order in $\nu$, are determined by the
Fourier spectra of the Newtonian mass octupole, Newtonian current quadrupole,
and 1PN part of the mass quadrupole moments. We also develop a conjectured (but
plausible) form for 1PN correction to the leading logs at second order in
$\nu$. Further, in analogy to the first paper, we show that these same source
multipole moments also yield nontrivial parts of the 1PN correction to the
subleading-logarithm series, and that the remaining eccentricity dependence (at
lowest order in $\nu$) can then more easily be determined using black hole
perturbation theory. We use this method to determine the entire analytic
eccentricity dependence of the perturbative (i.e., lowest order in $\nu$) 4PN
non-log terms, $\mathcal{R}_4(e_t)$ and $\mathcal{Z}_4(e_t)$, for energy and
angular momentum respectively.
| [
{
"created": "Wed, 2 Sep 2020 18:00:07 GMT",
"version": "v1"
}
] | 2020-11-11 | [
[
"Munna",
"Christopher",
""
],
[
"Evans",
"Charles R.",
""
]
] | In a recent paper we showed that for eccentric-orbit extreme-mass-ratio inspirals the analytic forms of the leading-logarithm energy and angular momentum post-Newtonian (PN) flux terms (radiated to infinity) can, to arbitrary PN order, be determined by sums over the Fourier spectrum of the Newtonian quadrupole moment. We further showed that an essential part of the eccentricity dependence of the related subleading-logarithm PN sequences, at lowest order in the symmetric mass ratio $\nu$, stems as well from the Newtonian quadrupole moment. Once that part is factored out, the remaining eccentricity dependence is more easily determined by black hole perturbation theory. In this paper we show how the sequences that are the 1PN corrections to the entire leading-logarithm series, namely terms that appear at PN orders $x^{3k+1} \log^k(x)$ and $x^{3k+5/2} \log^k(x)$ (for PN compactness parameter $x$ and integers $k\ge 0$), at lowest order in $\nu$, are determined by the Fourier spectra of the Newtonian mass octupole, Newtonian current quadrupole, and 1PN part of the mass quadrupole moments. We also develop a conjectured (but plausible) form for 1PN correction to the leading logs at second order in $\nu$. Further, in analogy to the first paper, we show that these same source multipole moments also yield nontrivial parts of the 1PN correction to the subleading-logarithm series, and that the remaining eccentricity dependence (at lowest order in $\nu$) can then more easily be determined using black hole perturbation theory. We use this method to determine the entire analytic eccentricity dependence of the perturbative (i.e., lowest order in $\nu$) 4PN non-log terms, $\mathcal{R}_4(e_t)$ and $\mathcal{Z}_4(e_t)$, for energy and angular momentum respectively. |
2307.00977 | Haidar Sheikhahmadi | Hassan Firouzjahi, Haidar Sheikhahmadi | Vacuum Zero Point Energy and its Statistical Correlations in dS
Background | 23 pages | Phys. Rev. D 108, 065002, 2023 | 10.1103/PhysRevD.108.065002 | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | We study the vacuum zero point energy associated to a scalar field with an
arbitrary mass and conformal coupling in a dS background. Employing dimensional
regularization scheme, we calculate the regularized zero point energy density,
pressure and the trace of the energy momentum tensor. It is shown that the
classical relation $\langle T \rangle =-4 \langle \rho \rangle$ for the vacuum
stress energy tensor receives anomalous quantum correction which depends on the
mass and the conformal coupling while the relation $\langle \rho \rangle = -
\langle P \rangle$ does hold. We calculate the density contrast associated to
the vacuum zero point energy and show that $\delta \rho \sim \langle \rho
\rangle$ indicating an inhomogeneous and non-perturbative distribution of the
zero point energy. Finally, we calculate the skewness associated to the
distribution of the zero point energy and pressure and show that they are
highly non-Gaussian.
| [
{
"created": "Mon, 3 Jul 2023 12:46:26 GMT",
"version": "v1"
}
] | 2023-09-25 | [
[
"Firouzjahi",
"Hassan",
""
],
[
"Sheikhahmadi",
"Haidar",
""
]
] | We study the vacuum zero point energy associated to a scalar field with an arbitrary mass and conformal coupling in a dS background. Employing dimensional regularization scheme, we calculate the regularized zero point energy density, pressure and the trace of the energy momentum tensor. It is shown that the classical relation $\langle T \rangle =-4 \langle \rho \rangle$ for the vacuum stress energy tensor receives anomalous quantum correction which depends on the mass and the conformal coupling while the relation $\langle \rho \rangle = - \langle P \rangle$ does hold. We calculate the density contrast associated to the vacuum zero point energy and show that $\delta \rho \sim \langle \rho \rangle$ indicating an inhomogeneous and non-perturbative distribution of the zero point energy. Finally, we calculate the skewness associated to the distribution of the zero point energy and pressure and show that they are highly non-Gaussian. |
gr-qc/0403005 | Sang Pyo Kim | Sang Pyo Kim (Kunsan Nat'l Univ.), Don N. Page (Univ. Alberta) | Magnetic Black Holes Are Also Unstable | RevTex4; Invited talk by Don N. Page at VI APCTP International
Conference of Gravitation and Astrophysics (ICGA6); Seoul, Oct. 6-9, 2003 | J.Korean Phys.Soc. 45 (2004) S59-S67 | null | null | gr-qc hep-th | null | Most black holes are known to be unstable to emitting Hawking radiation (in
asymptotically flat spacetime). If the black holes are non-extreme, they have
positive temperature and emit thermally. If they are extremal rotating black
holes, they still spontaneously emit particles like gravitons and photons. If
they are extremal electrically charged black holes, they are unstable to
emitting electrons or positrons. The only exception would be extreme
magnetically charged black holes if there do not exist any magnetic monopoles
for them to emit. However, here we show that even in this case, vacuum
polarization causes all magnetic black holes to be unstable to emitting smaller
magnetic black holes.
| [
{
"created": "Sun, 29 Feb 2004 09:10:03 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Kim",
"Sang Pyo",
"",
"Kunsan Nat'l Univ."
],
[
"Page",
"Don N.",
"",
"Univ. Alberta"
]
] | Most black holes are known to be unstable to emitting Hawking radiation (in asymptotically flat spacetime). If the black holes are non-extreme, they have positive temperature and emit thermally. If they are extremal rotating black holes, they still spontaneously emit particles like gravitons and photons. If they are extremal electrically charged black holes, they are unstable to emitting electrons or positrons. The only exception would be extreme magnetically charged black holes if there do not exist any magnetic monopoles for them to emit. However, here we show that even in this case, vacuum polarization causes all magnetic black holes to be unstable to emitting smaller magnetic black holes. |
1905.02318 | Jin Pu | Jin Pu, Sen Guo, Qing-Quan Jiang, Xiao-Tao Zu | Joule-Thomson expansion for the regular(Bardeen)-AdS black hole | 17 pages, 6 figures; Added discussion in section 4 | null | 10.1088/1674-1137/44/3/035102 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we attempt to study the Joule-Thomson expansion for the
regular black hole in an anti-de Sitter background, and obtain the inversion
temperature and curve for the Bardeen-AdS black hole in the extended phase
space. We investigate the isenthalpic and inversion curves for the Bardeen-AdS
black hole in the T-P plane to find the intersection points between them are
exactly the inversion points discriminating the heating process from the
cooling one. And, the inversion curve for the regular(Bardeen)-AdS black hole
is not closed and there is only a lower inversion curve in contrast with that
of the Van der Walls fluid. Most importantly, we find the ratio between the
minimum inversion and critical temperature for the regular(Bardeen)-AdS black
hole is 0.536622, which is always larger than all the already-known ratios for
the singular black hole. This larger ratio for the Bardeen-AdS black hole in
contrast with the singular black hole may stem from the fact that there is a
repulsive de Sitter core near the origin of the regular black hole.
| [
{
"created": "Sat, 4 May 2019 08:25:10 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Jul 2019 14:32:51 GMT",
"version": "v2"
}
] | 2020-05-08 | [
[
"Pu",
"Jin",
""
],
[
"Guo",
"Sen",
""
],
[
"Jiang",
"Qing-Quan",
""
],
[
"Zu",
"Xiao-Tao",
""
]
] | In this paper, we attempt to study the Joule-Thomson expansion for the regular black hole in an anti-de Sitter background, and obtain the inversion temperature and curve for the Bardeen-AdS black hole in the extended phase space. We investigate the isenthalpic and inversion curves for the Bardeen-AdS black hole in the T-P plane to find the intersection points between them are exactly the inversion points discriminating the heating process from the cooling one. And, the inversion curve for the regular(Bardeen)-AdS black hole is not closed and there is only a lower inversion curve in contrast with that of the Van der Walls fluid. Most importantly, we find the ratio between the minimum inversion and critical temperature for the regular(Bardeen)-AdS black hole is 0.536622, which is always larger than all the already-known ratios for the singular black hole. This larger ratio for the Bardeen-AdS black hole in contrast with the singular black hole may stem from the fact that there is a repulsive de Sitter core near the origin of the regular black hole. |
2201.05209 | Camilo Posada PhD | Camilo Posada, Jan Hlad\'ik and Zden\v{e}k Stuchl\'ik | New interior model of neutron stars | 10 pages, 10 figures. Matches version accepted for publication in
Phys. Rev. D | Phys. Rev. D 105, 104020 (2022) | 10.1103/PhysRevD.105.104020 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Tolman VII solution is considered by some as one of the few analytical
solutions to Einstein's equations, which describes approximately well the
interior of neutron stars (NSs). This solution is characterized by the mass
$M$, radius $R$, and an energy density that varies quadratically with the
radial coordinate $r$. Recently, Jiang and Yagi proposed a modification of this
solution, the so-called modified Tolman VII (MTVII) solution, by introducing an
additional quartic term to the energy density radial profile. The MTVII
solution is an approximate solution to Einstein's equation, which includes a
new parameter $\alpha$ that allows the solution to have a better agreement with
the energy density profiles for realistic NSs. Here we consider the MTVII
solution, showing that for certain values of the parameter $\alpha$ and
compactness $\mathcal{C}$ this solution manifests a region of negative pressure
near the surface which leads to negative values of the tidal Love number. To
alleviate these drawbacks, we introduce an exact version of the MTVII solution
obtained by solving numerically Einstein's equations for the MTVII energy
density profile. As an application of our new exact MTVII (EMTVII) solution, we
calculate the tidal Love number and tidal deformability, as a function of
$\mathcal{C}$, for different values of the parameter $\alpha$. We find that the
EMTVII solution predicts a positive tidal Love number for the whole range of
allowed values of parameters $(\mathcal{C},\alpha)$, in agreement with previous
results for realistic NSs.
| [
{
"created": "Thu, 13 Jan 2022 20:57:37 GMT",
"version": "v1"
},
{
"created": "Wed, 4 May 2022 09:21:40 GMT",
"version": "v2"
}
] | 2022-05-16 | [
[
"Posada",
"Camilo",
""
],
[
"Hladík",
"Jan",
""
],
[
"Stuchlík",
"Zdeněk",
""
]
] | The Tolman VII solution is considered by some as one of the few analytical solutions to Einstein's equations, which describes approximately well the interior of neutron stars (NSs). This solution is characterized by the mass $M$, radius $R$, and an energy density that varies quadratically with the radial coordinate $r$. Recently, Jiang and Yagi proposed a modification of this solution, the so-called modified Tolman VII (MTVII) solution, by introducing an additional quartic term to the energy density radial profile. The MTVII solution is an approximate solution to Einstein's equation, which includes a new parameter $\alpha$ that allows the solution to have a better agreement with the energy density profiles for realistic NSs. Here we consider the MTVII solution, showing that for certain values of the parameter $\alpha$ and compactness $\mathcal{C}$ this solution manifests a region of negative pressure near the surface which leads to negative values of the tidal Love number. To alleviate these drawbacks, we introduce an exact version of the MTVII solution obtained by solving numerically Einstein's equations for the MTVII energy density profile. As an application of our new exact MTVII (EMTVII) solution, we calculate the tidal Love number and tidal deformability, as a function of $\mathcal{C}$, for different values of the parameter $\alpha$. We find that the EMTVII solution predicts a positive tidal Love number for the whole range of allowed values of parameters $(\mathcal{C},\alpha)$, in agreement with previous results for realistic NSs. |
0904.1359 | Leonardo Fernandez-Jambrina | L. Fern\'andez-Jambrina, L.M. Gonz\'alez-Romero | Non-singular Stiff Fluids | 4 pp, ws-procs | Proceedings of the Tenth Marcel Grossmann Meeting on General
Relativity. Ed: M. Novello, S. Perez Bergliaffa. World Scientific, Singapore,
1764-6 (2006) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this talk the possibility of constructing geodesically complete
inhomogeneous stiff fluid cosmologies is discussed. A family with infinite
parameters is derived. A wide and easy to implement sufficient condition for
geodesic completeness is shown.
| [
{
"created": "Wed, 8 Apr 2009 15:07:26 GMT",
"version": "v1"
}
] | 2009-04-09 | [
[
"Fernández-Jambrina",
"L.",
""
],
[
"González-Romero",
"L. M.",
""
]
] | In this talk the possibility of constructing geodesically complete inhomogeneous stiff fluid cosmologies is discussed. A family with infinite parameters is derived. A wide and easy to implement sufficient condition for geodesic completeness is shown. |
2402.04135 | Claus Lammerzahl | Claus Lammerzahl (Univ. Bremen) and Sebastian Ulbricht (PTB
Braunschweig) | A gravitational metrological triangle | 8 pages, 5 Figures | null | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | Motivated by the similarity of the mathematical structure of Einstein's
General Relativity in its weak field limit and of Maxwell's theory of
electrodynamics it is shown that there are gravitational analogues of the
Josephson effect and the quantum Hall effect. These effects can be combined to
derive a gravitational analogue of the quantum/electric metrological triangle.
The gravitational metrological triangle may have applications in metrology and
could be used to investigate the relation of the Planck constant to fundamental
particle masses. This allows for quantum tests of the Weak Equivalence
Principle. Moreover, the similarity of the gravitational and the
quantum/electrical metrological triangle can be used to test the universality
of quantum mechanics.
| [
{
"created": "Tue, 6 Feb 2024 16:40:31 GMT",
"version": "v1"
}
] | 2024-02-07 | [
[
"Lammerzahl",
"Claus",
"",
"Univ. Bremen"
],
[
"Ulbricht",
"Sebastian",
"",
"PTB\n Braunschweig"
]
] | Motivated by the similarity of the mathematical structure of Einstein's General Relativity in its weak field limit and of Maxwell's theory of electrodynamics it is shown that there are gravitational analogues of the Josephson effect and the quantum Hall effect. These effects can be combined to derive a gravitational analogue of the quantum/electric metrological triangle. The gravitational metrological triangle may have applications in metrology and could be used to investigate the relation of the Planck constant to fundamental particle masses. This allows for quantum tests of the Weak Equivalence Principle. Moreover, the similarity of the gravitational and the quantum/electrical metrological triangle can be used to test the universality of quantum mechanics. |
gr-qc/9802033 | Shinsuke Kawai | Shinsuke Kawai, Masa-aki Sakagami and Jiro Soda | Instability of 1-loop superstring cosmology | 10 pages, 6 figures, revtex | Phys.Lett. B437 (1998) 284-290 | 10.1016/S0370-2693(98)00925-3 | KUCP0114 | gr-qc hep-th | null | A stability analysis is made in the context of the previously discovered
non-singular cosmological solution from 1-loop corrected superstring effective
action. We found that this solution has an instability in graviton mode, which
is shown to have a close relation to the avoidance of initial singularity via
energy condition. We also estimate the condition for the breakdown of the
background solution due to the overdominance of the graviton.
| [
{
"created": "Mon, 16 Feb 1998 04:49:41 GMT",
"version": "v1"
},
{
"created": "Mon, 11 May 1998 11:17:29 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Kawai",
"Shinsuke",
""
],
[
"Sakagami",
"Masa-aki",
""
],
[
"Soda",
"Jiro",
""
]
] | A stability analysis is made in the context of the previously discovered non-singular cosmological solution from 1-loop corrected superstring effective action. We found that this solution has an instability in graviton mode, which is shown to have a close relation to the avoidance of initial singularity via energy condition. We also estimate the condition for the breakdown of the background solution due to the overdominance of the graviton. |
2309.03144 | Aleksandra Go\v{c}anin | Ivana Stojiljkovi\'c, Du\v{s}an {\DJ}or{\dj}evi\'c, Aleksandra
Go\v{c}anin, and Dragoljub Go\v{c}anin | Testing the Braneworld Theory with Identical Particles | 6 pages, 6 figures, comments are welcome | Phys. Rev. D 108, 124008 (2023) | 10.1103/PhysRevD.108.124008 | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | Various attempts to go beyond the theory of General Relativity start from the
assumption that spacetime is not a 4-dimensional but rather a
higher-dimensional manifold. Among others, braneworld scenarios postulate that
the spacetime we effectively observe is actually a 4-dimensional brane embedded
in a higher-dimensional spacetime. In general, braneworld models predict a
departure from the Newton gravity law in the nonrelativistic regime. Based on
this fact, we propose an experimental test that uses a pair of gravitationally
interacting identical particles to determine the validity of certain braneworld
models and provide numerical results that should be compared with experimental
data. In particular, we consider the Randal-Sundrum braneworld model and study
two cases of 5-dimensional gravity theories: the Einstein-Hilbert gravity with
the negative cosmological constant and the Einstein-Gauss-Bonnet
(nearly-Chern-Simons) gravity.
| [
{
"created": "Wed, 6 Sep 2023 16:40:12 GMT",
"version": "v1"
}
] | 2024-01-31 | [
[
"Stojiljković",
"Ivana",
""
],
[
"Đorđević",
"Dušan",
""
],
[
"Gočanin",
"Aleksandra",
""
],
[
"Gočanin",
"Dragoljub",
""
]
] | Various attempts to go beyond the theory of General Relativity start from the assumption that spacetime is not a 4-dimensional but rather a higher-dimensional manifold. Among others, braneworld scenarios postulate that the spacetime we effectively observe is actually a 4-dimensional brane embedded in a higher-dimensional spacetime. In general, braneworld models predict a departure from the Newton gravity law in the nonrelativistic regime. Based on this fact, we propose an experimental test that uses a pair of gravitationally interacting identical particles to determine the validity of certain braneworld models and provide numerical results that should be compared with experimental data. In particular, we consider the Randal-Sundrum braneworld model and study two cases of 5-dimensional gravity theories: the Einstein-Hilbert gravity with the negative cosmological constant and the Einstein-Gauss-Bonnet (nearly-Chern-Simons) gravity. |
2208.10177 | Ningchen Bai | Ning-Chen Bai, Lei Li and Jun Tao | Topology of black hole thermodynamics in Lovelock gravity | 11 pages, 7 figures | null | 10.1103/PhysRevD.107.064015 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we present a convenient method to perform the topological
analysis of black hole thermodynamics. Utilizing the spinodal curve,
thermodynamic critical points of a black hole are endowed with a topological
quantity, Brouwer degree, which reflects intrinsic properties of the system
under smooth deformations. Specially, in our setup, it can be easily calculated
without exact solution of critical points. This enables us to conveniently
investigate the topological transition between different thermodynamic systems,
and give a topological classification for them. In this framework, topology of
Lovelock AdS black holes with spherical horizon geometry is explored. Results
show that charged black holes in arbitrary dimensions can be classified into
the same topology class, whereas the $d=7$ and $d \geq 8$ uncharged black holes
are in different topology classes. Moreover, we revisit the relation between
different phase structures of these black holes from the viewpoint of topology.
Some general topological properties of critical points are also discussed.
| [
{
"created": "Mon, 22 Aug 2022 09:42:47 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Aug 2022 09:55:32 GMT",
"version": "v2"
}
] | 2023-03-29 | [
[
"Bai",
"Ning-Chen",
""
],
[
"Li",
"Lei",
""
],
[
"Tao",
"Jun",
""
]
] | In this work, we present a convenient method to perform the topological analysis of black hole thermodynamics. Utilizing the spinodal curve, thermodynamic critical points of a black hole are endowed with a topological quantity, Brouwer degree, which reflects intrinsic properties of the system under smooth deformations. Specially, in our setup, it can be easily calculated without exact solution of critical points. This enables us to conveniently investigate the topological transition between different thermodynamic systems, and give a topological classification for them. In this framework, topology of Lovelock AdS black holes with spherical horizon geometry is explored. Results show that charged black holes in arbitrary dimensions can be classified into the same topology class, whereas the $d=7$ and $d \geq 8$ uncharged black holes are in different topology classes. Moreover, we revisit the relation between different phase structures of these black holes from the viewpoint of topology. Some general topological properties of critical points are also discussed. |
1104.3985 | Benny Rievers | Benny Rievers and Claus L\"ammerzahl | High precision thermal modeling of complex systems with application to
the flyby and Pioneer anomaly | Accepted for publication in Ann. Phys | null | 10.1002/andp.201100081 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Thermal modeling of complex systems faces the problems of an effective
digitalization of the detailed geometry and properties of the system,
calculation of the thermal flows and temperature maps, treatment of the thermal
radiation including possible multiple reflections, inclusion of additional
external influences, extraction of the radiation pressure from calculated
surface data, and computational effectiveness. In previous publications the
solution to these problems have been outlined and a first application to the
Pioneer spacecraft have been shown. Here we like to present the application of
our thermal modeling to the Rosetta flyby anomaly as well as to the Pioneer
anomaly. The analysis outlines that thermal recoil pressure is not the cause of
the Rosetta flyby anomaly but likely resolves the anomalous acceleration
observed for Pioneer 10.
| [
{
"created": "Wed, 20 Apr 2011 10:34:44 GMT",
"version": "v1"
},
{
"created": "Thu, 5 May 2011 10:10:32 GMT",
"version": "v2"
}
] | 2015-05-27 | [
[
"Rievers",
"Benny",
""
],
[
"Lämmerzahl",
"Claus",
""
]
] | Thermal modeling of complex systems faces the problems of an effective digitalization of the detailed geometry and properties of the system, calculation of the thermal flows and temperature maps, treatment of the thermal radiation including possible multiple reflections, inclusion of additional external influences, extraction of the radiation pressure from calculated surface data, and computational effectiveness. In previous publications the solution to these problems have been outlined and a first application to the Pioneer spacecraft have been shown. Here we like to present the application of our thermal modeling to the Rosetta flyby anomaly as well as to the Pioneer anomaly. The analysis outlines that thermal recoil pressure is not the cause of the Rosetta flyby anomaly but likely resolves the anomalous acceleration observed for Pioneer 10. |
2006.03376 | Davide Batic | M. Alrais Alawadi, D. Batic, M. Nowakowski | Light bending in a two black hole metric | 27 pages, 3 figures, updated bibliography | null | 10.1088/1361-6382/abce6c | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the propagation of light in the C-metric. We discover that null
geodesics admit circular orbits only for a certain family of orbital cones.
Explicit analytic formulae are derived for the orbital radius and the
corresponding opening angle fixing the cone. Furthermore, we prove that these
orbits based on a saddle point in the effective potential are Jacobi unstable.
This completes the stability analysis done in previous literature and allows us
to probe into the light bending in a two black hole metric. More precisely, by
constructing a suitable tetrad in the Newmann-Penrose formalism, we show that
light propagation in this geometry is shear-free, irrotational, and a light
beam passing by a C-black hole undergoes a focussing process. An exact analytic
formula for the compression factor $\theta$ is derived and discussed.
Furthermore, we study the weak and strong gravitational lensing when both the
observer and the light ray belong to the aforementioned family of invariant
cones. In particular, we obtain formulae allowing to calculate the deflection
angle in the weak and strong gravitational lensing regimes.
| [
{
"created": "Fri, 5 Jun 2020 11:22:43 GMT",
"version": "v1"
},
{
"created": "Sat, 12 Dec 2020 12:11:14 GMT",
"version": "v2"
},
{
"created": "Sun, 19 Nov 2023 10:17:21 GMT",
"version": "v3"
}
] | 2023-11-21 | [
[
"Alawadi",
"M. Alrais",
""
],
[
"Batic",
"D.",
""
],
[
"Nowakowski",
"M.",
""
]
] | We discuss the propagation of light in the C-metric. We discover that null geodesics admit circular orbits only for a certain family of orbital cones. Explicit analytic formulae are derived for the orbital radius and the corresponding opening angle fixing the cone. Furthermore, we prove that these orbits based on a saddle point in the effective potential are Jacobi unstable. This completes the stability analysis done in previous literature and allows us to probe into the light bending in a two black hole metric. More precisely, by constructing a suitable tetrad in the Newmann-Penrose formalism, we show that light propagation in this geometry is shear-free, irrotational, and a light beam passing by a C-black hole undergoes a focussing process. An exact analytic formula for the compression factor $\theta$ is derived and discussed. Furthermore, we study the weak and strong gravitational lensing when both the observer and the light ray belong to the aforementioned family of invariant cones. In particular, we obtain formulae allowing to calculate the deflection angle in the weak and strong gravitational lensing regimes. |
2205.11476 | Ali Ayatollah Rafsanjani | Behzad Ataei, Ali Ayatollah Rafsanjani, Alireza Bahrampour, Mohammad
Taeibi Rahni, Mohammadreza Salimi and Mehdi Golshani | An analogical model for the stationary black holes by the flow field of
space-time fluid around a 3-dimensional point sink | Keywords: general relativity; space-time fluid; analogue gravity;
acoustic metric; black hole; emergent gravity; Kerr metric; compressible flow | null | null | null | gr-qc hep-th physics.flu-dyn | http://creativecommons.org/licenses/by/4.0/ | Recent researches suggest an analogy between the theory of general relativity
(GR) and fluid dynamics. As a result of this analogy, the Navier-Stokes
equations and Einstein field equations are the same, and it is possible to
study the properties of space-time by using fluid mechanics. In this paper, we
present a new model to describe gravitational phenomena by an inviscid and
compressible fluid called space-time fluid (STF). The analogy method is used to
obtain the gravity field of both static and rotating masses from the flow field
of STF around static and rotating point sinks. In addition, event horizons and
the ergosphere of stationary black holes are defined based on our STF model.
Then, we compare hydrodynamic forces exerted on a test particle with
gravitational forces in the gravitoelectromagnetic approximation of the GR. As
a natural consequence, it is shown that inertial and gravitational masses are
equivalent in this analogy. Finally, using the aspect of fluid dynamics, Mach's
principle, weak equivalence principle, and information discontinuity on the
event horizon are discussed.
| [
{
"created": "Mon, 23 May 2022 17:25:00 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Nov 2022 11:15:05 GMT",
"version": "v2"
}
] | 2022-11-11 | [
[
"Ataei",
"Behzad",
""
],
[
"Rafsanjani",
"Ali Ayatollah",
""
],
[
"Bahrampour",
"Alireza",
""
],
[
"Rahni",
"Mohammad Taeibi",
""
],
[
"Salimi",
"Mohammadreza",
""
],
[
"Golshani",
"Mehdi",
""
]
] | Recent researches suggest an analogy between the theory of general relativity (GR) and fluid dynamics. As a result of this analogy, the Navier-Stokes equations and Einstein field equations are the same, and it is possible to study the properties of space-time by using fluid mechanics. In this paper, we present a new model to describe gravitational phenomena by an inviscid and compressible fluid called space-time fluid (STF). The analogy method is used to obtain the gravity field of both static and rotating masses from the flow field of STF around static and rotating point sinks. In addition, event horizons and the ergosphere of stationary black holes are defined based on our STF model. Then, we compare hydrodynamic forces exerted on a test particle with gravitational forces in the gravitoelectromagnetic approximation of the GR. As a natural consequence, it is shown that inertial and gravitational masses are equivalent in this analogy. Finally, using the aspect of fluid dynamics, Mach's principle, weak equivalence principle, and information discontinuity on the event horizon are discussed. |
gr-qc/0408065 | Morad Amarzguioui | Morad Amarzguioui and Oyvind Gron | Entropy of gravitationally collapsing matter in FRW universe models | 9 pages, 4 figures. Major changes from previous version. We consider
only thermodynamic entropy in this version. Published in PRD | Phys. Rev. D71, 083011 (2005) | 10.1103/PhysRevD.71.083011 | null | gr-qc astro-ph | null | We look at a gas of dust and investigate how its entropy evolves with time
under a spherically symmetric gravitational collapse. We treat the problem
perturbatively and find that the classical thermodynamic entropy does actually
increase to first order when one allows for gravitational potential energy to
be transferred to thermal energy during the collapse. Thus, in this situation
there is no need to resort to the introduction of an intrinsic gravitational
entropy in order to satisfy the second law of thermodynamics.
| [
{
"created": "Thu, 19 Aug 2004 10:34:33 GMT",
"version": "v1"
},
{
"created": "Fri, 20 May 2005 14:05:09 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Amarzguioui",
"Morad",
""
],
[
"Gron",
"Oyvind",
""
]
] | We look at a gas of dust and investigate how its entropy evolves with time under a spherically symmetric gravitational collapse. We treat the problem perturbatively and find that the classical thermodynamic entropy does actually increase to first order when one allows for gravitational potential energy to be transferred to thermal energy during the collapse. Thus, in this situation there is no need to resort to the introduction of an intrinsic gravitational entropy in order to satisfy the second law of thermodynamics. |
1507.08453 | Cosimo Bambi | Cosimo Bambi, M. Ghasemi-Nodehi, D. Rubiera-Garcia | Modified gravity in three dimensional metric-affine scenarios | 9 pages, 4 figures, some differences with respect to the version
accepted for publication | Phys. Rev. D 92, 044016 (2015) | 10.1103/PhysRevD.92.044016 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider metric-affine scenarios where a modified gravitational action is
sourced by electrovacuum fields in a three dimensional space-time. Such
scenarios are supported by the physics of crystalline structures with
microscopic defects and, in particular, those that can be effectively treated
as bi-dimensional (like graphene). We first study the case of $f(R)$ theories,
finding deviations near the center as compared to the solutions of General
Relativity. We then consider Born-Infeld gravity, which has raised a lot of
interest in the last few years regarding its applications in astrophysics and
cosmology, and show that new features always arise at a finite distance from
the center. Several properties of the resulting space-times, in particular in
presence of a cosmological constant term, are discussed.
| [
{
"created": "Thu, 30 Jul 2015 11:08:19 GMT",
"version": "v1"
}
] | 2015-08-13 | [
[
"Bambi",
"Cosimo",
""
],
[
"Ghasemi-Nodehi",
"M.",
""
],
[
"Rubiera-Garcia",
"D.",
""
]
] | We consider metric-affine scenarios where a modified gravitational action is sourced by electrovacuum fields in a three dimensional space-time. Such scenarios are supported by the physics of crystalline structures with microscopic defects and, in particular, those that can be effectively treated as bi-dimensional (like graphene). We first study the case of $f(R)$ theories, finding deviations near the center as compared to the solutions of General Relativity. We then consider Born-Infeld gravity, which has raised a lot of interest in the last few years regarding its applications in astrophysics and cosmology, and show that new features always arise at a finite distance from the center. Several properties of the resulting space-times, in particular in presence of a cosmological constant term, are discussed. |
0806.0339 | Giovanni Amelino-Camelia | Giovanni Amelino-Camelia | Quantum Spacetime Phenomenology | 125 pages, LaTex. This V2 is updated and more detailed than the V1,
particularly for quantum-spacetime phenomenology. The main text of this V2 is
about 25% more than the main text of the V1. Reference list roughly doubled | Living Rev.Rel. 16 (2013) 5 | 10.12942/lrr-2013-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I review the current status of phenomenological programs inspired by
quantum-spacetime research. I stress in particular the significance of results
establishing that certain data analyses provide sensitivity to effects
introduced genuinely at the Planck scale. And my main focus is on
phenomenological programs that managed to affect the directions taken by
studies of quantum-spacetime theories.
| [
{
"created": "Mon, 2 Jun 2008 17:21:44 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Jun 2013 07:08:36 GMT",
"version": "v2"
}
] | 2015-11-18 | [
[
"Amelino-Camelia",
"Giovanni",
""
]
] | I review the current status of phenomenological programs inspired by quantum-spacetime research. I stress in particular the significance of results establishing that certain data analyses provide sensitivity to effects introduced genuinely at the Planck scale. And my main focus is on phenomenological programs that managed to affect the directions taken by studies of quantum-spacetime theories. |
1410.2548 | Christian Schell | Christian Schell and Oliver Rinne | Spectral approach to axisymmetric evolution of Einstein's equations | 6 pages, based on a talk given by one of the authors at the Spanish
Relativity Meeting ERE14 in Valencia, published version | 2015 J. Phys.: Conf. Ser. 600 012060 | 10.1088/1742-6596/600/1/012060 | AEI-2014-055 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new formulation of Einstein's equations for an axisymmetric
spacetime with vanishing twist in vacuum. We propose a fully constrained scheme
and use spherical polar coordinates. A general problem for this choice is the
occurrence of coordinate singularities on the axis of symmetry and at the
origin. Spherical harmonics are manifestly regular on the axis and hence take
care of that issue automatically. In addition a spectral approach has
computational advantages when the equations are implemented. Therefore we
spectrally decompose all the variables in the appropriate harmonics. A central
point in the formulation is the gauge choice. One of our results is that the
commonly used maximal-isothermal gauge turns out to be incompatible with tensor
harmonic expansions, and we introduce a new gauge that is better suited. We
also address the regularisation of the coordinate singularity at the origin.
| [
{
"created": "Thu, 9 Oct 2014 17:57:33 GMT",
"version": "v1"
},
{
"created": "Thu, 14 May 2015 11:04:44 GMT",
"version": "v2"
}
] | 2015-05-15 | [
[
"Schell",
"Christian",
""
],
[
"Rinne",
"Oliver",
""
]
] | We present a new formulation of Einstein's equations for an axisymmetric spacetime with vanishing twist in vacuum. We propose a fully constrained scheme and use spherical polar coordinates. A general problem for this choice is the occurrence of coordinate singularities on the axis of symmetry and at the origin. Spherical harmonics are manifestly regular on the axis and hence take care of that issue automatically. In addition a spectral approach has computational advantages when the equations are implemented. Therefore we spectrally decompose all the variables in the appropriate harmonics. A central point in the formulation is the gauge choice. One of our results is that the commonly used maximal-isothermal gauge turns out to be incompatible with tensor harmonic expansions, and we introduce a new gauge that is better suited. We also address the regularisation of the coordinate singularity at the origin. |
0803.2288 | Samad Khakshournia | Samad Khakshournia | A Note on the Generalized Friedmann Equations for a Thick Brane | 6 pages,To appear in GRG | Gen.Rel.Grav.40:1791-1796,2008 | 10.1007/s10714-007-0578-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Within our thick brane approach previously used to obtain the cosmological
evolution equations on a thick brane embedded in a five-dimensional
Schwarzschild Anti-de Sitter spacetime it is explicitly shown that the
consistency of these equations with the energy conservation equation requires
that, in general, the thickness of the brane evolves in time. This varying
brane thickness entails the possibility that both Newton's gravitational
constant $G$ and the effective cosmological constant $\Lambda_4$ are time
dependent.
| [
{
"created": "Sat, 15 Mar 2008 11:49:56 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Khakshournia",
"Samad",
""
]
] | Within our thick brane approach previously used to obtain the cosmological evolution equations on a thick brane embedded in a five-dimensional Schwarzschild Anti-de Sitter spacetime it is explicitly shown that the consistency of these equations with the energy conservation equation requires that, in general, the thickness of the brane evolves in time. This varying brane thickness entails the possibility that both Newton's gravitational constant $G$ and the effective cosmological constant $\Lambda_4$ are time dependent. |
2012.15111 | Maurice Dupre | Maurice J. Dupr\'e | The Jacobi Curvature Operator in Semi Riemannian Geometry and the Energy
Momentum Stress Tensor of the Gravitational Field | 110 pages. arXiv admin note: substantial text overlap with
arXiv:0903.5225, arXiv:1403.2618, arXiv:0803.1684 | null | null | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a justification for generalizing the notion of the energy momentum
stress tensor in general relativity which results in the Jacobi curvature
tensor being the embodiment of total energy momentum stress including gravity
in general relativity.
| [
{
"created": "Wed, 30 Dec 2020 11:01:42 GMT",
"version": "v1"
}
] | 2021-01-01 | [
[
"Dupré",
"Maurice J.",
""
]
] | We give a justification for generalizing the notion of the energy momentum stress tensor in general relativity which results in the Jacobi curvature tensor being the embodiment of total energy momentum stress including gravity in general relativity. |
gr-qc/9801067 | William Krivan | Manuela Campanelli, William Krivan, and Carlos O. Lousto | The imposition of Cauchy data to the Teukolsky equation II: Numerical
comparison with the Zerilli-Moncrief approach to black hole perturbations | 14 pages, 7 Postscript figures, to appear in Phys. Rev. D | Phys. Rev. D 58, 024016 (1998) | 10.1103/PhysRevD.58.024016 | null | gr-qc astro-ph hep-th | null | We revisit the question of the imposition of initial data representing
astrophysical gravitational perturbations of black holes. We study their
dynamics for the case of nonrotating black holes by numerically evolving the
Teukolsky equation in the time domain. In order to express the Teukolsky
function Psi explicitly in terms of hypersurface quantities, we relate it to
the Moncrief waveform phi_M through a Chandrasekhar transformation in the case
of a nonrotating black hole. This relation between Psi and phi_M holds for any
constant time hypersurface and allows us to compare the computation of the
evolution of Schwarzschild perturbations by the Teukolsky and by the Zerilli
and Regge-Wheeler equations. We explicitly perform this comparison for the
Misner initial data in the close limit approach. We evolve numerically both,
the Teukolsky (with the recent code of Ref. [1]) and the Zerilli equations,
finding complete agreement in resulting waveforms within numerical error. The
consistency of these results further supports the correctness of the numerical
code for evolving the Teukolsky equation as well as the analytic expressions
for Psi in terms only of the three-metric and the extrinsic curvature.
| [
{
"created": "Tue, 20 Jan 1998 17:58:46 GMT",
"version": "v1"
},
{
"created": "Fri, 8 May 1998 16:54:15 GMT",
"version": "v2"
}
] | 2016-08-25 | [
[
"Campanelli",
"Manuela",
""
],
[
"Krivan",
"William",
""
],
[
"Lousto",
"Carlos O.",
""
]
] | We revisit the question of the imposition of initial data representing astrophysical gravitational perturbations of black holes. We study their dynamics for the case of nonrotating black holes by numerically evolving the Teukolsky equation in the time domain. In order to express the Teukolsky function Psi explicitly in terms of hypersurface quantities, we relate it to the Moncrief waveform phi_M through a Chandrasekhar transformation in the case of a nonrotating black hole. This relation between Psi and phi_M holds for any constant time hypersurface and allows us to compare the computation of the evolution of Schwarzschild perturbations by the Teukolsky and by the Zerilli and Regge-Wheeler equations. We explicitly perform this comparison for the Misner initial data in the close limit approach. We evolve numerically both, the Teukolsky (with the recent code of Ref. [1]) and the Zerilli equations, finding complete agreement in resulting waveforms within numerical error. The consistency of these results further supports the correctness of the numerical code for evolving the Teukolsky equation as well as the analytic expressions for Psi in terms only of the three-metric and the extrinsic curvature. |
2408.02647 | Eug\^enio Bastos Maciel | Eug\^enio Bastos Maciel, M.A. Anacleto, E. Passos | Gravitational Dipole Moment in Braneworld Model | 11 pages, one table | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the gravitational effects on the relativistic Dirac theory of
a system such as a Hydrogen atom in the braneworld scenario. A gravitational
dipole moment like contribution, arises in the nonrelativistic Hamiltonian of
the system through an exact Foldy-Wouthuysen transformation. This term violates
the equivalence principle for the weak interaction that is restored in the
average over the spins. Furthermore, it feels the effects of the extra
dimensions, so that in a Universe with two additional spatial dimensions its
energy contribution is amplified by an order of $\sim 10^{16}\ \text{eV}$
concerning to the energy of this term for ordinary space. The compactification
radius for a Universe with two extra dimensions is within the experimental
limits, where deviations from the inverse square law are being tested. This
suggests that the energy value for the gravitational dipole term in this
scenario may lead us to search for traces of extra dimensions in atomic
spectroscopy, as well as experimental constraints for these dimensions.
| [
{
"created": "Mon, 5 Aug 2024 17:24:44 GMT",
"version": "v1"
}
] | 2024-08-06 | [
[
"Maciel",
"Eugênio Bastos",
""
],
[
"Anacleto",
"M. A.",
""
],
[
"Passos",
"E.",
""
]
] | We investigate the gravitational effects on the relativistic Dirac theory of a system such as a Hydrogen atom in the braneworld scenario. A gravitational dipole moment like contribution, arises in the nonrelativistic Hamiltonian of the system through an exact Foldy-Wouthuysen transformation. This term violates the equivalence principle for the weak interaction that is restored in the average over the spins. Furthermore, it feels the effects of the extra dimensions, so that in a Universe with two additional spatial dimensions its energy contribution is amplified by an order of $\sim 10^{16}\ \text{eV}$ concerning to the energy of this term for ordinary space. The compactification radius for a Universe with two extra dimensions is within the experimental limits, where deviations from the inverse square law are being tested. This suggests that the energy value for the gravitational dipole term in this scenario may lead us to search for traces of extra dimensions in atomic spectroscopy, as well as experimental constraints for these dimensions. |
gr-qc/9501033 | Bernd Stoetzel | Bernd Stoetzel | Two-dimensional gravitation and Sine-Gordon-Solitons | 23 pages, latex, references added, to appear in Phys.Rev.D | Phys.Rev. D52 (1995) 2192-2201 | 10.1103/PhysRevD.52.2192 | null | gr-qc | null | Some aspects of two-dimensional gravity coupled to matter fields, especially
to the Sine-Gordon-model are examined. General properties and boundary
conditions of possible soliton-solutions are considered. Analytic
soliton-solutions are discovered and the structure of the induced space-time
geometry is discussed. These solutions have interesting features and may serve
as a starting point for further investigations.
| [
{
"created": "Wed, 25 Jan 1995 21:36:24 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Jan 1995 18:34:25 GMT",
"version": "v2"
},
{
"created": "Fri, 7 Jul 1995 15:40:25 GMT",
"version": "v3"
}
] | 2009-10-28 | [
[
"Stoetzel",
"Bernd",
""
]
] | Some aspects of two-dimensional gravity coupled to matter fields, especially to the Sine-Gordon-model are examined. General properties and boundary conditions of possible soliton-solutions are considered. Analytic soliton-solutions are discovered and the structure of the induced space-time geometry is discussed. These solutions have interesting features and may serve as a starting point for further investigations. |
gr-qc/9803003 | Yoonbai Kim | Yoonbai Kim and Sei-Hoon Moon | Gravitating $\sigma$ Model Solitons | 35 pages, RevTeX | Phys.Rev.D58:105013,1998 | 10.1103/PhysRevD.58.105013 | SNUTP-97-112 | gr-qc | null | We study axially symmetric static solitons of O(3) nonlinear $\sigma$ model
coupled to (2+1)-dimensional anti-de Sitter gravity. The obtained solutions are
not self-dual under static metric. The usual regular topological lump solution
cannot form a black hole even though the scale of symmetry breaking is
increased. There exist nontopological solitons of half integral winding in a
given model, and the corresponding spacetimes involve charged Ba$\tilde
n$ados-Teitelboim-Zanelli black holes without non-Abelian scalar hair.
| [
{
"created": "Sun, 1 Mar 1998 08:11:05 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Kim",
"Yoonbai",
""
],
[
"Moon",
"Sei-Hoon",
""
]
] | We study axially symmetric static solitons of O(3) nonlinear $\sigma$ model coupled to (2+1)-dimensional anti-de Sitter gravity. The obtained solutions are not self-dual under static metric. The usual regular topological lump solution cannot form a black hole even though the scale of symmetry breaking is increased. There exist nontopological solitons of half integral winding in a given model, and the corresponding spacetimes involve charged Ba$\tilde n$ados-Teitelboim-Zanelli black holes without non-Abelian scalar hair. |
2401.09477 | \"Ozg\"ur \"Okc\"u | \"Ozg\"ur \"Okc\"u | Investigation of generalised uncertainty principle effects on FRW
cosmology | 22 pages, 3 figures, 4 tables, 1 appendix | NPB 1004 (2024) 116551 | 10.1016/j.nuclphysb.2024.116551 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Based on the entropy-area relation from Nouicer's generalised uncertainty
principle (GUP), we derive the GUP modified Friedmann equations from the first
law of thermodynamics at apparent horizon. We find a minimum apparent horizon
due to the minimal length notion of GUP. We show that the energy density of
universe has a maximum and finite value at the minimum apparent horizon. Both
minimum apparent horizon and maximum energy density imply the absence of the
Big Bang singularity. Moreover, we investigate the GUP effects on the
deceleration parameter for flat case. Finally, we examine the validity of
generalised second law (GSL) of thermodynamics. We show that GSL always holds
in a region enclosed by apparent horizon for the GUP effects. We also
investigate the GSL in $\Lambda CDM$ cosmology and find that the total entropy
change of universe has a maximum value in the presence of GUP effects. To
better grasp the effects of Nouicer's GUP on cosmology, we compare our results
with those obtained from quadratic GUP (QGUP).
| [
{
"created": "Mon, 15 Jan 2024 02:06:37 GMT",
"version": "v1"
},
{
"created": "Sat, 27 Apr 2024 23:07:30 GMT",
"version": "v2"
}
] | 2024-04-30 | [
[
"Ökcü",
"Özgür",
""
]
] | Based on the entropy-area relation from Nouicer's generalised uncertainty principle (GUP), we derive the GUP modified Friedmann equations from the first law of thermodynamics at apparent horizon. We find a minimum apparent horizon due to the minimal length notion of GUP. We show that the energy density of universe has a maximum and finite value at the minimum apparent horizon. Both minimum apparent horizon and maximum energy density imply the absence of the Big Bang singularity. Moreover, we investigate the GUP effects on the deceleration parameter for flat case. Finally, we examine the validity of generalised second law (GSL) of thermodynamics. We show that GSL always holds in a region enclosed by apparent horizon for the GUP effects. We also investigate the GSL in $\Lambda CDM$ cosmology and find that the total entropy change of universe has a maximum value in the presence of GUP effects. To better grasp the effects of Nouicer's GUP on cosmology, we compare our results with those obtained from quadratic GUP (QGUP). |
2104.06631 | Kai Lin | Kai Lin, Yang-Yi Sun and Hongsheng Zhang | Quasinormal Modes for Dynamical Black Holes | null | Phys.Rev.D 103, 084015 (2021) | 10.1103/PhysRevD.103.084015 | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | Realistic black holes are usually dynamical, noticeable or sluggish. The
Vaidya metric is a significant and tractable model for simulating a dynamical
black hole. In this study, we consider scalar perturbations in a dynamical
Vaidya black hole, and explore the quasinormal modes by employing the matrix
method. We find the proper boundary conditions of the quasinormal modes from
physical analysis in the background of a dynamical black hole for the first
time. The results show that the eigenfrequencies become different at the
apparent horizon and null infinity, because the physical interactions propagate
with finite velocity in nature. Any variation of the hole does not affect the
boundary condition at null infinity in a finite time. The quasinormal modes
originated around the horizon would not immediately come down to, but slowly
goes to the final state following the mass accretion process of the hole. The
precision of the matrix method is quite compelling, which reveals more details
of the eigenfrequencies of the quasinormal mode of perturbations in the Vaidya
spacetime.
| [
{
"created": "Wed, 14 Apr 2021 05:23:48 GMT",
"version": "v1"
}
] | 2021-04-15 | [
[
"Lin",
"Kai",
""
],
[
"Sun",
"Yang-Yi",
""
],
[
"Zhang",
"Hongsheng",
""
]
] | Realistic black holes are usually dynamical, noticeable or sluggish. The Vaidya metric is a significant and tractable model for simulating a dynamical black hole. In this study, we consider scalar perturbations in a dynamical Vaidya black hole, and explore the quasinormal modes by employing the matrix method. We find the proper boundary conditions of the quasinormal modes from physical analysis in the background of a dynamical black hole for the first time. The results show that the eigenfrequencies become different at the apparent horizon and null infinity, because the physical interactions propagate with finite velocity in nature. Any variation of the hole does not affect the boundary condition at null infinity in a finite time. The quasinormal modes originated around the horizon would not immediately come down to, but slowly goes to the final state following the mass accretion process of the hole. The precision of the matrix method is quite compelling, which reveals more details of the eigenfrequencies of the quasinormal mode of perturbations in the Vaidya spacetime. |
2111.13575 | Carla Rodrigues Almeida | Carla Rodrigues Almeida and Denis Campos Rodrigues | Quantization of a Black-Hole Gravity: geometrodynamics and the quantum
phase-space formalism | 13 pages, 3 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Quantum gravity is effective in domains where both quantum effects and
gravity are essential, such as in the vicinity of space-time singularities.
This paper will investigate the quantization of a black-hole gravity,
particularly the region surrounding the singularity at the origin of the
coordinate system. Describing the system with a Hamiltonian formalism, we apply
the covariant integral quantization method to find the Wheeler-DeWitt equation
of the model. We find that the quantized system has a discrete energy spectrum
in the region inside the event horizon. Through the Kantowski-Sachs metric, it
is possible to correlate the entropic time, which gives the dynamics for this
model, to the cosmic time in a non-trivial way. Different configurations for
the phase space of a Schwarzschild black hole are obtained in a semi-classical
analysis. For lower-energy states, the quantum corrections result in
singularity removal and wormhole formation.
| [
{
"created": "Fri, 26 Nov 2021 16:19:47 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Feb 2022 11:26:46 GMT",
"version": "v2"
},
{
"created": "Wed, 14 Sep 2022 19:09:50 GMT",
"version": "v3"
}
] | 2022-09-16 | [
[
"Almeida",
"Carla Rodrigues",
""
],
[
"Rodrigues",
"Denis Campos",
""
]
] | Quantum gravity is effective in domains where both quantum effects and gravity are essential, such as in the vicinity of space-time singularities. This paper will investigate the quantization of a black-hole gravity, particularly the region surrounding the singularity at the origin of the coordinate system. Describing the system with a Hamiltonian formalism, we apply the covariant integral quantization method to find the Wheeler-DeWitt equation of the model. We find that the quantized system has a discrete energy spectrum in the region inside the event horizon. Through the Kantowski-Sachs metric, it is possible to correlate the entropic time, which gives the dynamics for this model, to the cosmic time in a non-trivial way. Different configurations for the phase space of a Schwarzschild black hole are obtained in a semi-classical analysis. For lower-energy states, the quantum corrections result in singularity removal and wormhole formation. |
2205.03312 | Riccardo Falcone | Riccardo Falcone and Claudio Conti | Observing single-particles beyond the Rindler horizon | null | Phys. Rev. A 107, 030203 (2023) | 10.1103/PhysRevA.107.L030203 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that Minkowski single-particle states localized beyond the horizon
modify the Unruh thermal distribution in an accelerated frame. This means that,
contrary to classical predictions, accelerated observers can reveal particles
emitted beyond the horizon. The method we adopt is based on deriving the
explicit Wigner characteristic function for the complete description of the
quantum field in the non-inertial frame and can be generalized to general
states.
| [
{
"created": "Fri, 6 May 2022 15:47:56 GMT",
"version": "v1"
}
] | 2023-06-06 | [
[
"Falcone",
"Riccardo",
""
],
[
"Conti",
"Claudio",
""
]
] | We show that Minkowski single-particle states localized beyond the horizon modify the Unruh thermal distribution in an accelerated frame. This means that, contrary to classical predictions, accelerated observers can reveal particles emitted beyond the horizon. The method we adopt is based on deriving the explicit Wigner characteristic function for the complete description of the quantum field in the non-inertial frame and can be generalized to general states. |
2005.13965 | Gon\c{c}alo Quinta | Gon\c{c}alo M. Quinta | Classical and Quantum Thermodynamic Systems in Curved Spacetime | PhD thesis, Instituto Superior Tecnico, December 2018. 189 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Systems at finite temperature make up the vast majority of realistic physical
scenarios. Indeed, although zero temperature is often accompanied by simpler
mathematics, the richness in physical results is evident when one considers the
system to have temperature and even more so if the background geometry is
curved. This thesis will be dedicated to the study of this type of physical
systems, where thermodynamics and general relativity equally contribute to the
dynamics. The first part will be devoted to the study of classical
thermodynamic systems in curved spacetime, namely thin matter shells at finite
temperature. These objects partition spacetime into separate pieces, and their
very existence is conditioned by the so-called junctions conditions. The latter
conditions allow us to carefully study both the mechanical and thermodynamics
of the shell and, in particular, they give rise to a well-defined notion of
entropy. The shell can then be taken to its black hole limit, providing an
alternative way to study black hole thermodynamics. We will do this for
different geometries, obtaining as byproduct a plausible answer for the debated
value of the entropy of an extremal black hole. In the second part we shall
review the standard formalisms to study QFT in curved spacetimes, in order to
explore quantum properties of thermodynamic systems in the presence of gravity.
Massive quantum scalar fields at finite temperature will be the systems of
choice, whereby various instances of vacuum polarisation will be calculated in
a variety of black hole geometries. Both numerical and analytic results will be
obtained, and new addition formulas for a certain class of transcendental
functions will be derived. This part will culminate with a careful numerical
study of symmetry restoration of a self-interacting scalar field around a
charged black hole, where we verify insights present in the literature.
| [
{
"created": "Thu, 28 May 2020 13:10:17 GMT",
"version": "v1"
}
] | 2020-05-29 | [
[
"Quinta",
"Gonçalo M.",
""
]
] | Systems at finite temperature make up the vast majority of realistic physical scenarios. Indeed, although zero temperature is often accompanied by simpler mathematics, the richness in physical results is evident when one considers the system to have temperature and even more so if the background geometry is curved. This thesis will be dedicated to the study of this type of physical systems, where thermodynamics and general relativity equally contribute to the dynamics. The first part will be devoted to the study of classical thermodynamic systems in curved spacetime, namely thin matter shells at finite temperature. These objects partition spacetime into separate pieces, and their very existence is conditioned by the so-called junctions conditions. The latter conditions allow us to carefully study both the mechanical and thermodynamics of the shell and, in particular, they give rise to a well-defined notion of entropy. The shell can then be taken to its black hole limit, providing an alternative way to study black hole thermodynamics. We will do this for different geometries, obtaining as byproduct a plausible answer for the debated value of the entropy of an extremal black hole. In the second part we shall review the standard formalisms to study QFT in curved spacetimes, in order to explore quantum properties of thermodynamic systems in the presence of gravity. Massive quantum scalar fields at finite temperature will be the systems of choice, whereby various instances of vacuum polarisation will be calculated in a variety of black hole geometries. Both numerical and analytic results will be obtained, and new addition formulas for a certain class of transcendental functions will be derived. This part will culminate with a careful numerical study of symmetry restoration of a self-interacting scalar field around a charged black hole, where we verify insights present in the literature. |
0708.2013 | Peter D'Eath | A.N.St.J.Farley, P.D. D'Eath | Quantum amplitudes in black-hole evaporation: Spins 1 and 2 | null | AnnalsPhys.321:1334-1374,2006 | 10.1016/j.aop.2005.11.011 | null | gr-qc | null | Quantum amplitudes for $s=1$ at Maxwell fields and for $s=2$ linearised
gravitational wave perturbations of a spherically symmetric Einstein/massless
scalar background, describing gravitational collapse to a black hole, are
treated by analogy with a previous treatment of $s=0$ scalar-field
perturbations of gravitational collapse at late times. In both the $s=1$ and
$s=2$ cases, we isolate suitable 'co-ordinate' variables which can be taken as
boundary data on a final space-like hypersurface $\Sigma_F$. For simplicity, we
take the data on an initial pre-collapse surface $\Sigma_I$ to be exactly
spherically symmetric. The (large) Lorentzian proper-time interval between
$\Sigma_{I}, \Sigma_{F}$, measured at spatial infinity, is denoted by $T$. The
complexified classical boundary-value problem is expected to be well-posed,
provide that the time interval $T$ has been rotated into the complex:
$T\to{\mid}T{\mid}\exp(-i\theta)$, for $0<\theta\leq{\pi}/2$. We calculate the
second-variation classical Lorenztian action $S ^{(2)}_{\rm class}$. Following
Feynman, we recover the Lorentzian quantum amplitude by taking the limit as
$\theta\to 0_+$ of the semi-classical amplitude $\exp(iS^{(2)}_{\rm class})$.
The boundary data for $ s=1$ involve the Maxwell magnetic field; the data for
$s=2$ involve the magnetic part of the Weyl curvature tensor. The magnetic
boundary conditions are related to each other and to the natural $s={1 \over
2}$ boundary conditions by supersymmetry.
| [
{
"created": "Wed, 15 Aug 2007 09:38:25 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Farley",
"A. N. St. J.",
""
],
[
"D'Eath",
"P. D.",
""
]
] | Quantum amplitudes for $s=1$ at Maxwell fields and for $s=2$ linearised gravitational wave perturbations of a spherically symmetric Einstein/massless scalar background, describing gravitational collapse to a black hole, are treated by analogy with a previous treatment of $s=0$ scalar-field perturbations of gravitational collapse at late times. In both the $s=1$ and $s=2$ cases, we isolate suitable 'co-ordinate' variables which can be taken as boundary data on a final space-like hypersurface $\Sigma_F$. For simplicity, we take the data on an initial pre-collapse surface $\Sigma_I$ to be exactly spherically symmetric. The (large) Lorentzian proper-time interval between $\Sigma_{I}, \Sigma_{F}$, measured at spatial infinity, is denoted by $T$. The complexified classical boundary-value problem is expected to be well-posed, provide that the time interval $T$ has been rotated into the complex: $T\to{\mid}T{\mid}\exp(-i\theta)$, for $0<\theta\leq{\pi}/2$. We calculate the second-variation classical Lorenztian action $S ^{(2)}_{\rm class}$. Following Feynman, we recover the Lorentzian quantum amplitude by taking the limit as $\theta\to 0_+$ of the semi-classical amplitude $\exp(iS^{(2)}_{\rm class})$. The boundary data for $ s=1$ involve the Maxwell magnetic field; the data for $s=2$ involve the magnetic part of the Weyl curvature tensor. The magnetic boundary conditions are related to each other and to the natural $s={1 \over 2}$ boundary conditions by supersymmetry. |
2311.06061 | Ajit Mehta | Ajit Kumar Mehta, Seth Olsen, Digvijay Wadekar, Javier Roulet, Tejaswi
Venumadhav, Jonathan Mushkin, Barak Zackay, Matias Zaldarriaga | New binary black hole mergers in the LIGO-Virgo O3b data | 16 pages, 12 figures | null | null | null | gr-qc astro-ph.HE astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | We report the detection of 6 new candidate binary black hole (BBH) merger
signals in the publicly released data from the second half of the third
observing run (O3b) of advanced LIGO and advanced Virgo. The LIGO-Virgo-KAGRA
(LVK) collaboration reported 35 compact binary coalescences (CBCs) in their
analysis of the O3b data [1], with 30 BBH mergers having coincidence in the
Hanford and Livingston detectors. We confirm 17 of these for a total of 23
detections in our analysis of the Hanford-Livingston coincident O3b data. We
identify candidates using a search pipeline employing aligned-spin
quadrupole-only waveforms. Our pipeline is similar to the one used in our O3a
coincident analysis [2], except for a few improvements in the veto procedure
and the ranking statistic, and we continue to use an astrophysical probability
of one half as our detection threshold, following the approach of the LVK
catalogs. Most of the new candidates reported in this work are placed in the
upper and lower-mass gap of the black hole (BH) mass distribution. We also
identify a possible neutron star-black hole (NSBH) merger. We expect these
events to help inform the black hole mass and spin distributions inferred in a
full population analysis.
| [
{
"created": "Fri, 10 Nov 2023 13:50:45 GMT",
"version": "v1"
},
{
"created": "Sat, 4 May 2024 23:01:28 GMT",
"version": "v2"
}
] | 2024-05-07 | [
[
"Mehta",
"Ajit Kumar",
""
],
[
"Olsen",
"Seth",
""
],
[
"Wadekar",
"Digvijay",
""
],
[
"Roulet",
"Javier",
""
],
[
"Venumadhav",
"Tejaswi",
""
],
[
"Mushkin",
"Jonathan",
""
],
[
"Zackay",
"Barak",
""
],
... | We report the detection of 6 new candidate binary black hole (BBH) merger signals in the publicly released data from the second half of the third observing run (O3b) of advanced LIGO and advanced Virgo. The LIGO-Virgo-KAGRA (LVK) collaboration reported 35 compact binary coalescences (CBCs) in their analysis of the O3b data [1], with 30 BBH mergers having coincidence in the Hanford and Livingston detectors. We confirm 17 of these for a total of 23 detections in our analysis of the Hanford-Livingston coincident O3b data. We identify candidates using a search pipeline employing aligned-spin quadrupole-only waveforms. Our pipeline is similar to the one used in our O3a coincident analysis [2], except for a few improvements in the veto procedure and the ranking statistic, and we continue to use an astrophysical probability of one half as our detection threshold, following the approach of the LVK catalogs. Most of the new candidates reported in this work are placed in the upper and lower-mass gap of the black hole (BH) mass distribution. We also identify a possible neutron star-black hole (NSBH) merger. We expect these events to help inform the black hole mass and spin distributions inferred in a full population analysis. |
1507.00103 | Prayush Kumar | Prayush Kumar, Kevin Barkett, Swetha Bhagwat, Nousha Afshari, Duncan
A. Brown, Geoffrey Lovelace, Mark A. Scheel, B\'ela Szil\'agyi | Accuracy and precision of gravitational-wave models of inspiraling
neutron star -- black hole binaries with spin: comparison with numerical
relativity in the low-frequency regime | 20 pages, 18 figures | Phys. Rev. D 92, 102001 (2015) | 10.1103/PhysRevD.92.102001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Coalescing binaries of neutron stars (NS) and black holes (BH) are one of the
most important sources of gravitational waves for the upcoming network of
ground based detectors. Detection and extraction of astrophysical information
from gravitational-wave signals requires accurate waveform models. The
Effective-One-Body and other phenomenological models interpolate between
analytic results and $10-30$ orbit numerical relativity (NR) merger
simulations. In this paper we study the accuracy of these models using new NR
simulations that span $36-88$ orbits, with mass-ratios and black hole spins
$(q,\chi_{BH}) = (7, \pm 0.4), (7, \pm 0.6)$, and $(5, -0.9)$. We find that:
(i) the recently published SEOBNRv1 and SEOBNRv2 models of the
Effective-One-Body family disagree with each other (mismatches of a few
percent) for black hole spins $\geq 0.5$ or $\leq -0.3$, with waveform mismatch
accumulating during early inspiral; (ii) comparison with numerical waveforms
indicate that this disagreement is due to phasing errors of SEOBNRv1, with
SEOBNRv2 in good agreement with all of our simulations; (iii) Phenomenological
waveforms disagree with SEOBNRv2 over most of the NSBH binary parameter space;
(iv) comparison with NR waveforms shows that most of the model's dephasing
accumulates near the frequency interval where it switches to a phenomenological
phasing prescription; and finally (v) both SEOBNR and post-Newtonian (PN)
models are effectual for NSBH systems, but PN waveforms will give a significant
bias in parameter recovery. Our results suggest that future gravitational-wave
detection searches and parameter estimation efforts targeted at NSBH systems
with $q\lesssim 7$ and $\chi_\mathrm{BH} \approx [-0.9, +0.6]$ will benefit
from using SEOBNRv2 templates. For larger black hole spins and/or binary
mass-ratios, we recommend the models be further investigated as suitable NR
simulations become available.
| [
{
"created": "Wed, 1 Jul 2015 05:06:59 GMT",
"version": "v1"
}
] | 2016-08-08 | [
[
"Kumar",
"Prayush",
""
],
[
"Barkett",
"Kevin",
""
],
[
"Bhagwat",
"Swetha",
""
],
[
"Afshari",
"Nousha",
""
],
[
"Brown",
"Duncan A.",
""
],
[
"Lovelace",
"Geoffrey",
""
],
[
"Scheel",
"Mark A.",
""
],
... | Coalescing binaries of neutron stars (NS) and black holes (BH) are one of the most important sources of gravitational waves for the upcoming network of ground based detectors. Detection and extraction of astrophysical information from gravitational-wave signals requires accurate waveform models. The Effective-One-Body and other phenomenological models interpolate between analytic results and $10-30$ orbit numerical relativity (NR) merger simulations. In this paper we study the accuracy of these models using new NR simulations that span $36-88$ orbits, with mass-ratios and black hole spins $(q,\chi_{BH}) = (7, \pm 0.4), (7, \pm 0.6)$, and $(5, -0.9)$. We find that: (i) the recently published SEOBNRv1 and SEOBNRv2 models of the Effective-One-Body family disagree with each other (mismatches of a few percent) for black hole spins $\geq 0.5$ or $\leq -0.3$, with waveform mismatch accumulating during early inspiral; (ii) comparison with numerical waveforms indicate that this disagreement is due to phasing errors of SEOBNRv1, with SEOBNRv2 in good agreement with all of our simulations; (iii) Phenomenological waveforms disagree with SEOBNRv2 over most of the NSBH binary parameter space; (iv) comparison with NR waveforms shows that most of the model's dephasing accumulates near the frequency interval where it switches to a phenomenological phasing prescription; and finally (v) both SEOBNR and post-Newtonian (PN) models are effectual for NSBH systems, but PN waveforms will give a significant bias in parameter recovery. Our results suggest that future gravitational-wave detection searches and parameter estimation efforts targeted at NSBH systems with $q\lesssim 7$ and $\chi_\mathrm{BH} \approx [-0.9, +0.6]$ will benefit from using SEOBNRv2 templates. For larger black hole spins and/or binary mass-ratios, we recommend the models be further investigated as suitable NR simulations become available. |
0906.1474 | Bijan Saha | Bijan Saha | Spinor model of a perfect fluid and their applications in Bianchi type-I
and FRW models | 10 pages, 8 Figures | Astrophys.Space Sci.331 (2011) 243 - 255 | 10.1007/s10509-010-0419-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Different characteristic of matter influencing the evolution of the Universe
has been simulated by means of a nonlinear spinor field. Exploiting the spinor
description of perfect fluid and dark energy evolution of the Universe given by
an anisotropic Bianchi type-I (BI) or isotropic Friedmann-Robertson-Walker
(FRW) one has been studied.
| [
{
"created": "Mon, 8 Jun 2009 11:58:56 GMT",
"version": "v1"
}
] | 2015-05-01 | [
[
"Saha",
"Bijan",
""
]
] | Different characteristic of matter influencing the evolution of the Universe has been simulated by means of a nonlinear spinor field. Exploiting the spinor description of perfect fluid and dark energy evolution of the Universe given by an anisotropic Bianchi type-I (BI) or isotropic Friedmann-Robertson-Walker (FRW) one has been studied. |
1305.3479 | Michele Arzano | Michele Arzano, Stefano Bianco and Olaf Dreyer | From bricks to quasinormal modes: A new perspective on black hole
entropy | Honorable Mention in the 2013 Gravity Research Foundation Essay
Competition | null | 10.1142/S0218271813420273 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Calculations of black hole entropy based on the counting of modes of a
quantum field propagating in a Schwarzschild background need to be regularized
in the vicinity of the horizon. To obtain the Bekenstein-Hawking result the
short distance cut-off needs to be fixed by hand. In this note we give an
argument for obtaining this cut-off in a natural fashion. We do this by
modelling the black hole by its set of quasinormal modes. The horizon then
becomes a extended region: the quantum ergosphere. The interaction of the
quantum ergosphere and the quantum field provides a natural regularization
mechanism. The width of the quantum ergosphere provides the right cut-off for
the entropy calculation. We arrive at a dual picture of black hole entropy. The
entropy of the black hole is given both by the entropy of the quantum field in
the bulk and the dynamical degrees of freedom on the horizon.
| [
{
"created": "Wed, 15 May 2013 14:01:33 GMT",
"version": "v1"
}
] | 2015-06-15 | [
[
"Arzano",
"Michele",
""
],
[
"Bianco",
"Stefano",
""
],
[
"Dreyer",
"Olaf",
""
]
] | Calculations of black hole entropy based on the counting of modes of a quantum field propagating in a Schwarzschild background need to be regularized in the vicinity of the horizon. To obtain the Bekenstein-Hawking result the short distance cut-off needs to be fixed by hand. In this note we give an argument for obtaining this cut-off in a natural fashion. We do this by modelling the black hole by its set of quasinormal modes. The horizon then becomes a extended region: the quantum ergosphere. The interaction of the quantum ergosphere and the quantum field provides a natural regularization mechanism. The width of the quantum ergosphere provides the right cut-off for the entropy calculation. We arrive at a dual picture of black hole entropy. The entropy of the black hole is given both by the entropy of the quantum field in the bulk and the dynamical degrees of freedom on the horizon. |
1006.4424 | Viktor G. Czinner | Viktor G. Czinner | Thick brane solutions and topology change transition on black hole
backgrounds | 11 pages, 10 figures, accepted for publication in Phys. Rev. D | Phys.Rev.D82:024035,2010 | 10.1103/PhysRevD.82.024035 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider static, axisymmetric, thick brane solutions on higher
dimensional, spherically symmetric black hole backgrounds. It was found
recently [1], that in cases when the thick brane has more than 2 spacelike
dimensions, perturbative approaches break down around the corresponding thin
solutions for Minkowski type topologies. This behavior is a consequence of the
fact that thin solutions are not smooth at the axis, and for a general
discussion of possible phase transitions in the system, one needs to use a
non-perturbative approach. In the present paper we provide an exact, numerical
solution of the problem both for black hole- and Minkowski type topologies with
arbitrary number of brane and bulk dimensions. We also illustrate a topology
change transition in the system for a 5-dimensional brane embedded in a
6-dimensional bulk.
| [
{
"created": "Wed, 23 Jun 2010 06:24:34 GMT",
"version": "v1"
}
] | 2014-11-21 | [
[
"Czinner",
"Viktor G.",
""
]
] | We consider static, axisymmetric, thick brane solutions on higher dimensional, spherically symmetric black hole backgrounds. It was found recently [1], that in cases when the thick brane has more than 2 spacelike dimensions, perturbative approaches break down around the corresponding thin solutions for Minkowski type topologies. This behavior is a consequence of the fact that thin solutions are not smooth at the axis, and for a general discussion of possible phase transitions in the system, one needs to use a non-perturbative approach. In the present paper we provide an exact, numerical solution of the problem both for black hole- and Minkowski type topologies with arbitrary number of brane and bulk dimensions. We also illustrate a topology change transition in the system for a 5-dimensional brane embedded in a 6-dimensional bulk. |
2302.02690 | Francois Larrouturou | Luc Blanchet and Lavinia Heisenberg and Fran\c{c}ois Larrouturou | Absence of gravitational polarization mechanism in the canonical
bimetric theory | 8 pages | Phys. Rev. D 107, 124021 (2023) | 10.1103/PhysRevD.107.124021 | DESY-23-010 | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | Motivated by a version of the ``Dipolar Dark Matter'' model, that aims at a
relativistic completion of the phenomenology of MOND, we investigate the
gravitational polarization mechanism in the canonical bimetric theory with an
effective matter coupling. We explicitly show the fundamental obstacle why such
theories cannot achieve a consistent gravitational polarization, and thus fail
to recover the MONDian phenomenology at low energies.
| [
{
"created": "Mon, 6 Feb 2023 10:46:40 GMT",
"version": "v1"
}
] | 2023-06-13 | [
[
"Blanchet",
"Luc",
""
],
[
"Heisenberg",
"Lavinia",
""
],
[
"Larrouturou",
"François",
""
]
] | Motivated by a version of the ``Dipolar Dark Matter'' model, that aims at a relativistic completion of the phenomenology of MOND, we investigate the gravitational polarization mechanism in the canonical bimetric theory with an effective matter coupling. We explicitly show the fundamental obstacle why such theories cannot achieve a consistent gravitational polarization, and thus fail to recover the MONDian phenomenology at low energies. |
2304.04180 | Abhik Kumar Sanyal Dr. | Manas Chakrabortty, Nayem Sk and Abhik Kumar Sanyal | A viable form of the metric Teleparallel F(T) theory of gravity | 12 pages, 0 figures | null | 10.1140/epjc/s10052-023-11741-2 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Unlike F(R) gravity, pure metric F(T) gravity in the vacuum dominated era,
ends up with an imaginary action and is therefore not feasible. This eerie
situation may only be circumvented by associating a scalar field, which can
also drive inflation in the very early universe. We show that, despite diverse
claims, F(T) theory admits Noether symmetry only in the pressure-less dust era
in the form F(T) proportional to the nth power of T, n being odd integers. A
suitable form of F(T), admitting a viable Friedmann-like radiation dominated
era, together with early deceleration and late-time accelerated expansion in
the pressure-less dust era, has been proposed.
| [
{
"created": "Sun, 9 Apr 2023 07:31:48 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Apr 2023 00:15:44 GMT",
"version": "v2"
}
] | 2023-07-26 | [
[
"Chakrabortty",
"Manas",
""
],
[
"Sk",
"Nayem",
""
],
[
"Sanyal",
"Abhik Kumar",
""
]
] | Unlike F(R) gravity, pure metric F(T) gravity in the vacuum dominated era, ends up with an imaginary action and is therefore not feasible. This eerie situation may only be circumvented by associating a scalar field, which can also drive inflation in the very early universe. We show that, despite diverse claims, F(T) theory admits Noether symmetry only in the pressure-less dust era in the form F(T) proportional to the nth power of T, n being odd integers. A suitable form of F(T), admitting a viable Friedmann-like radiation dominated era, together with early deceleration and late-time accelerated expansion in the pressure-less dust era, has been proposed. |
1412.4003 | Sarfraz Ali | Muhammad Jamil Amir and Sarfraz Ali | Spherical Symmetric Gravitational Collapse in Chern-Simon Modified
Gravity | 17 page | Int. J. Theor. Phys. (2016) 55: 2040 | 10.1007/s10773-015-2844-3 | 3-015-2844-3 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper is devoted to investigate the gravitational perfect fluid collapse
in the framework of Chern-Simon modified gravity. For this purpose, we assume
the spherically symmetric metric as an interior region and the Schwarzchild
spacetime is considered as an exterior region of the star. The Israel junction
conditions are used to match the interior and exterior spacetimes. For the sake
of simplicity, we take the external field $\Theta$ as a function of time
parameter $t$ and obtain the solution of the field equations of Chern-Simon
modified gravity. Junction conditions have been used to calculate the
gravitational mass. We discuss the apparent horizons and their physical
consequences. It is mentioning here that our results will reduce to those of
general relativity, available in literature, if the external field is taken to
be constant.
| [
{
"created": "Thu, 11 Dec 2014 11:59:54 GMT",
"version": "v1"
},
{
"created": "Tue, 26 May 2015 10:39:49 GMT",
"version": "v2"
}
] | 2019-05-21 | [
[
"Amir",
"Muhammad Jamil",
""
],
[
"Ali",
"Sarfraz",
""
]
] | This paper is devoted to investigate the gravitational perfect fluid collapse in the framework of Chern-Simon modified gravity. For this purpose, we assume the spherically symmetric metric as an interior region and the Schwarzchild spacetime is considered as an exterior region of the star. The Israel junction conditions are used to match the interior and exterior spacetimes. For the sake of simplicity, we take the external field $\Theta$ as a function of time parameter $t$ and obtain the solution of the field equations of Chern-Simon modified gravity. Junction conditions have been used to calculate the gravitational mass. We discuss the apparent horizons and their physical consequences. It is mentioning here that our results will reduce to those of general relativity, available in literature, if the external field is taken to be constant. |
2310.00913 | Aneta Wojnar | Aleksander Kozak, Anna Pacho\l, Aneta Wojnar | Refining Bounds for Snyder and GUP Models through Seismic Wave Analysis | 8 pages, 3 figures, typos corrected | null | null | null | gr-qc astro-ph.EP hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This study investigates possibility of placing bounds on the parameters,
arising from the non-commutative Snyder space-time model and Generalized
Uncertainty Principle (GUP) approach, by utilizing seismic data. We investigate
the dependence of constraints on the type of realization used for the quantum
phase space. Results indicate improved bounds compared to prior studies, with
the model parameter $\beta_0$ constrained to be less than $5.2\times 10^{44}$
for certain choice of realizations. This approach demonstrates the potential
for using Earth's empirical data to refine constraints on GUP parameters.
| [
{
"created": "Mon, 2 Oct 2023 05:58:23 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Apr 2024 09:17:10 GMT",
"version": "v2"
}
] | 2024-04-25 | [
[
"Kozak",
"Aleksander",
""
],
[
"Pachoł",
"Anna",
""
],
[
"Wojnar",
"Aneta",
""
]
] | This study investigates possibility of placing bounds on the parameters, arising from the non-commutative Snyder space-time model and Generalized Uncertainty Principle (GUP) approach, by utilizing seismic data. We investigate the dependence of constraints on the type of realization used for the quantum phase space. Results indicate improved bounds compared to prior studies, with the model parameter $\beta_0$ constrained to be less than $5.2\times 10^{44}$ for certain choice of realizations. This approach demonstrates the potential for using Earth's empirical data to refine constraints on GUP parameters. |
1801.10548 | Saulo Carneiro | Saulo Carneiro | Can the cosmological dark sector be modeled by a single scalar field? | 5 pages, version to appear in Gen. Relativ. Gravit | Gen Relativ Gravit (2018) 50: 114 | 10.1007/s10714-018-2439-4 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a previous paper it was shown that a minimally coupled scalar field of
mass $M \sim H_0$ can describe both components of the dark sector in a unified
way. In the solution found, the dark energy component decays linearly with the
Hubble parameter, with a homogeneous creation of dark matter. In the present
note we show that a $\Lambda$CDM dark sector can also be modeled by such a
single field. More generally, we show that the system of Klein-Gordon and
Einstein equations admits a uniparametric family of solutions that is
equivalent to a non-adiabatic (with zero sound speed) generalised Chaplygin
gas.
| [
{
"created": "Wed, 31 Jan 2018 16:58:51 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Aug 2018 13:18:01 GMT",
"version": "v2"
}
] | 2018-08-22 | [
[
"Carneiro",
"Saulo",
""
]
] | In a previous paper it was shown that a minimally coupled scalar field of mass $M \sim H_0$ can describe both components of the dark sector in a unified way. In the solution found, the dark energy component decays linearly with the Hubble parameter, with a homogeneous creation of dark matter. In the present note we show that a $\Lambda$CDM dark sector can also be modeled by such a single field. More generally, we show that the system of Klein-Gordon and Einstein equations admits a uniparametric family of solutions that is equivalent to a non-adiabatic (with zero sound speed) generalised Chaplygin gas. |
gr-qc/0112001 | Jonathan Oppenheim | J. Oppenheim | A Thermodynamic Sector of Quantum Gravity | null | null | null | null | gr-qc | null | The connection between gravity and thermodynamics is explored. Examining a
perfect fluid in gravitational equilibrium we find that the entropy is extremal
only if Einstein's equations are satisfied. Conversely, one can derive part of
Einstein's equations from ordinary thermodynamical considerations. This allows
the theory of this system to be recast in such a way that a sector of general
relativity is purely thermodynamical and should not be quantized.
| [
{
"created": "Tue, 4 Dec 2001 01:36:24 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Oppenheim",
"J.",
""
]
] | The connection between gravity and thermodynamics is explored. Examining a perfect fluid in gravitational equilibrium we find that the entropy is extremal only if Einstein's equations are satisfied. Conversely, one can derive part of Einstein's equations from ordinary thermodynamical considerations. This allows the theory of this system to be recast in such a way that a sector of general relativity is purely thermodynamical and should not be quantized. |
gr-qc/0202105 | Pablo Laguna | Pablo Laguna and Deirdre Shoemaker (Penn State) | Numerical stability of a new conformal-traceless 3+1 formulation of the
Einstein equation | 7 pages, 2 figures | Class.Quant.Grav. 19 (2002) 3679-3686 | 10.1088/0264-9381/19/14/309 | null | gr-qc | null | There is strong evidence indicating that the particular form used to recast
the Einstein equation as a 3+1 set of evolution equations has a fundamental
impact on the stability properties of numerical evolutions involving black
holes and/or neutron stars. Presently, the longest lived evolutions have been
obtained using a parametrized hyperbolic system developed by Kidder, Scheel and
Teukolsky or a conformal-traceless system introduced by Baumgarte, Shapiro,
Shibata and Nakamura. We present a new conformal-traceless system. While this
new system has some elements in common with the
Baumgarte-Shapiro-Shibata-Nakamura system, it differs in both the type of
conformal transformations and how the non-linear terms involving the extrinsic
curvature are handled. We show results from 3D numerical evolutions of a
single, non-rotating black hole in which we demonstrate that this new system
yields a significant improvement in the life-time of the simulations.
| [
{
"created": "Thu, 28 Feb 2002 20:10:07 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Laguna",
"Pablo",
"",
"Penn State"
],
[
"Shoemaker",
"Deirdre",
"",
"Penn State"
]
] | There is strong evidence indicating that the particular form used to recast the Einstein equation as a 3+1 set of evolution equations has a fundamental impact on the stability properties of numerical evolutions involving black holes and/or neutron stars. Presently, the longest lived evolutions have been obtained using a parametrized hyperbolic system developed by Kidder, Scheel and Teukolsky or a conformal-traceless system introduced by Baumgarte, Shapiro, Shibata and Nakamura. We present a new conformal-traceless system. While this new system has some elements in common with the Baumgarte-Shapiro-Shibata-Nakamura system, it differs in both the type of conformal transformations and how the non-linear terms involving the extrinsic curvature are handled. We show results from 3D numerical evolutions of a single, non-rotating black hole in which we demonstrate that this new system yields a significant improvement in the life-time of the simulations. |
1607.00364 | Hal Haggard | Hal M. Haggard and Carlo Rovelli | Quantum Gravity Effects around Sagittarius A* | 5 pages; Received honorable mention in the Gravity Research
Foundation 2016 Awards for Essays on Gravitation | null | 10.1142/S0218271816440211 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent VLBI observations have resolved Sagittarius A* at horizon scales. The
Event Horizon Telescope is expected to provide increasingly good images of the
region around the Schwarzschild radius $r_S$ of Sgr A* soon. A number of
authors have recently pointed out the possibility that non-perturbative quantum
gravitational phenomena could affect the space surrounding a black hole. Here
we point out that the existence of a region around $\frac76 r_S$ where these
effects should be maximal.
| [
{
"created": "Fri, 1 Jul 2016 19:39:10 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Jul 2016 19:50:15 GMT",
"version": "v2"
}
] | 2016-11-15 | [
[
"Haggard",
"Hal M.",
""
],
[
"Rovelli",
"Carlo",
""
]
] | Recent VLBI observations have resolved Sagittarius A* at horizon scales. The Event Horizon Telescope is expected to provide increasingly good images of the region around the Schwarzschild radius $r_S$ of Sgr A* soon. A number of authors have recently pointed out the possibility that non-perturbative quantum gravitational phenomena could affect the space surrounding a black hole. Here we point out that the existence of a region around $\frac76 r_S$ where these effects should be maximal. |
1410.5065 | Shuxuan Ying | Peng Wang, Haitang Yang, Shuxuan Ying | Quantum gravity corrections to the tunneling radiation of scalar
particles | V1, 13 pages | null | null | CTP-SCU/2014008 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The original derivation of Hawking radiation shows the complete evaporation
of black holes. However, theories of quantum gravity predict the existence of
the minimal observable length. In this paper, we investigate the tunneling
radiation of the scalar particles by introducing quantum gravity effects
influenced by the generalized uncertainty principle. The Hawking temperatures
are not only determined by the properties of the black holes, but also affected
by the quantum numbers of the emitted particles. The quantum gravity
corrections slow down the increase of the temperatures. The remnants are found
during the evaporation.
| [
{
"created": "Sun, 19 Oct 2014 12:47:44 GMT",
"version": "v1"
}
] | 2014-10-21 | [
[
"Wang",
"Peng",
""
],
[
"Yang",
"Haitang",
""
],
[
"Ying",
"Shuxuan",
""
]
] | The original derivation of Hawking radiation shows the complete evaporation of black holes. However, theories of quantum gravity predict the existence of the minimal observable length. In this paper, we investigate the tunneling radiation of the scalar particles by introducing quantum gravity effects influenced by the generalized uncertainty principle. The Hawking temperatures are not only determined by the properties of the black holes, but also affected by the quantum numbers of the emitted particles. The quantum gravity corrections slow down the increase of the temperatures. The remnants are found during the evaporation. |
gr-qc/0005092 | Eduardo Sergio Santini | E. Sergio Santini | Quantum Geometrodynamics in the Bohm-de Broglie Interpretation | PhD Thesis at CBPF-Rio de Janeiro-May 2000 (Advisor: N. Pinto-Neto,
95 pages, in Portuguese) | null | null | null | gr-qc hep-th quant-ph | null | In this thesis the Bohm-de Broglie interpretation of quantum mechanics is
applied to canonical quantum gravity. It is shown that, irrespective of any
regularization or choice of factor ordering of the Wheeler-DeWitt equation, the
unique relevant quantum effect which does not break spacetime is the change of
its signature from lorentzian to euclidean. The other quantum effects are
either trivial or break the four-geometry of spacetime. A Bohm-de Broglie
picture of quantum geometrodynamics is constructed, which allows the
investigation of these latter structures. For instance, it is shown that any
real solution of the Wheeler-De Witt equation yields a generate four-geometry
compatible with the strong gravity limit of General Relativity and the Carroll
group. We prove that quantum geometrodynamics in the Bohm-de Broglie
interpretation is consistent for any quantum potential. As a previous step to
introduce our metodology, we study the quantum theory of fields in Minkowski
spacetime in the Bohm-de Broglie interpretation and exhibit a concrete example
where Lorentz invariance of individual events is broken.
| [
{
"created": "Mon, 22 May 2000 02:31:26 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Santini",
"E. Sergio",
""
]
] | In this thesis the Bohm-de Broglie interpretation of quantum mechanics is applied to canonical quantum gravity. It is shown that, irrespective of any regularization or choice of factor ordering of the Wheeler-DeWitt equation, the unique relevant quantum effect which does not break spacetime is the change of its signature from lorentzian to euclidean. The other quantum effects are either trivial or break the four-geometry of spacetime. A Bohm-de Broglie picture of quantum geometrodynamics is constructed, which allows the investigation of these latter structures. For instance, it is shown that any real solution of the Wheeler-De Witt equation yields a generate four-geometry compatible with the strong gravity limit of General Relativity and the Carroll group. We prove that quantum geometrodynamics in the Bohm-de Broglie interpretation is consistent for any quantum potential. As a previous step to introduce our metodology, we study the quantum theory of fields in Minkowski spacetime in the Bohm-de Broglie interpretation and exhibit a concrete example where Lorentz invariance of individual events is broken. |
2401.03187 | Shi-Jie Ma | Shi-Jie Ma, Rui-Bo Wang, Jian-Bo Deng, Xian-Ru Hu | Euler-Heisenberg black hole surrounded by perfect fluid dark matter | 34 pages, 11 figures | null | 10.1140/epjc/s10052-024-12914-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A generation method of new metric in the case of static spherically symmetric
space-time is derived. Using this approach, we construct a metric which
describes Euler-Heisenberg black hole surrounded by perfect fluid dark matter
and investigate its optical and thermodynamic properties. We found that radius
of shadow will increase with the increase of dark matter effect, and more
strong dark matter will diminish the light intensity of accretion disk
generally. Moreover, in thermodynamics, when quantum electrodynamic parameter
is positive, there will be a critical value of dark matter parameter, which
determine the number of black hole's critical points.
| [
{
"created": "Sat, 6 Jan 2024 10:23:13 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Jun 2024 07:23:23 GMT",
"version": "v2"
},
{
"created": "Thu, 13 Jun 2024 01:42:57 GMT",
"version": "v3"
}
] | 2024-06-14 | [
[
"Ma",
"Shi-Jie",
""
],
[
"Wang",
"Rui-Bo",
""
],
[
"Deng",
"Jian-Bo",
""
],
[
"Hu",
"Xian-Ru",
""
]
] | A generation method of new metric in the case of static spherically symmetric space-time is derived. Using this approach, we construct a metric which describes Euler-Heisenberg black hole surrounded by perfect fluid dark matter and investigate its optical and thermodynamic properties. We found that radius of shadow will increase with the increase of dark matter effect, and more strong dark matter will diminish the light intensity of accretion disk generally. Moreover, in thermodynamics, when quantum electrodynamic parameter is positive, there will be a critical value of dark matter parameter, which determine the number of black hole's critical points. |
gr-qc/9903108 | Bruce Allen | B. Allen, J.K. Blackburn, P.R. Brady, J.D.E. Creighton, T. Creighton,
S. Droz, A.D. Gillespie, S.A. Hughes, S. Kawamura, T.T. Lyons, J.E. Mason,
B.J. Owen, F.J. Raab, M.W. Regehr, B.S. Sathyaprakash, R.L. Savage, Jr., S.
Whitcomb, and A.G. Wiseman | Observational Limit on Gravitational Waves from Binary Neutron Stars in
the Galaxy | RevTeX, minor revisions, exactly as published in PRL 83 (1999) p1498,
4 pages, 2 figures included | Phys.Rev.Lett.83:1498,1999 | 10.1103/PhysRevLett.83.1498 | WISC-MILW-99-TH-05,LIGO-P990019-01 | gr-qc astro-ph | null | Using optimal matched filtering, we search 25 hours of data from the LIGO
40-meter prototype laser interferometric gravitational-wave detector for
gravitational-wave chirps emitted by coalescing binary systems within our
Galaxy. This is the first test of this filtering technique on real
interferometric data. An upper limit on the rate R of neutron star binary
inspirals in our Galaxy is obtained: with 90% confidence, R< 0.5/hour. Similar
experiments with LIGO interferometers will provide constraints on the
population of tight binary neutron star systems in the Universe.
| [
{
"created": "Wed, 31 Mar 1999 01:58:56 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Sep 1999 15:15:28 GMT",
"version": "v2"
}
] | 2012-08-27 | [
[
"Allen",
"B.",
""
],
[
"Blackburn",
"J. K.",
""
],
[
"Brady",
"P. R.",
""
],
[
"Creighton",
"J. D. E.",
""
],
[
"Creighton",
"T.",
""
],
[
"Droz",
"S.",
""
],
[
"Gillespie",
"A. D.",
""
],
[
"Hughes... | Using optimal matched filtering, we search 25 hours of data from the LIGO 40-meter prototype laser interferometric gravitational-wave detector for gravitational-wave chirps emitted by coalescing binary systems within our Galaxy. This is the first test of this filtering technique on real interferometric data. An upper limit on the rate R of neutron star binary inspirals in our Galaxy is obtained: with 90% confidence, R< 0.5/hour. Similar experiments with LIGO interferometers will provide constraints on the population of tight binary neutron star systems in the Universe. |
gr-qc/9505030 | Eric Poisson | Eric Poisson | Gravitational radiation from a particle in circular orbit around a black
hole. VI. Accuracy of the post-Newtonian expansion | 5 pages, ReVTeX, 1 figure. A typographical error was discovered in
the computer code used to generate the results presented in the paper. The
corrected results are presented in an Erratum, which also incorporates new
results, obtained using the recently improved post-Newtonian calculations of
Tanaka, Tagoshi, and Sasaki | Phys.Rev. D52 (1995) 5719-5723; Addendum-ibid. D55 (1997)
7980-7981 | 10.1103/PhysRevD.52.5719 | null | gr-qc | null | A particle of mass $\mu$ moves on a circular orbit around a nonrotating black
hole of mass $M$. Under the assumption $\mu \ll M$ the gravitational waves
emitted by such a binary system can be calculated exactly numerically using
black-hole perturbation theory. If, further, the particle is slowly moving,
then the waves can be calculated approximately analytically, and expressed in
the form of a post-Newtonian expansion. We determine the accuracy of this
expansion in a quantitative way by calculating the reduction in signal-to-noise
ratio incurred when matched filtering the exact signal with a nonoptimal,
post-Newtonian filter.
| [
{
"created": "Wed, 17 May 1995 23:35:55 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Feb 1997 21:43:18 GMT",
"version": "v2"
}
] | 2009-10-28 | [
[
"Poisson",
"Eric",
""
]
] | A particle of mass $\mu$ moves on a circular orbit around a nonrotating black hole of mass $M$. Under the assumption $\mu \ll M$ the gravitational waves emitted by such a binary system can be calculated exactly numerically using black-hole perturbation theory. If, further, the particle is slowly moving, then the waves can be calculated approximately analytically, and expressed in the form of a post-Newtonian expansion. We determine the accuracy of this expansion in a quantitative way by calculating the reduction in signal-to-noise ratio incurred when matched filtering the exact signal with a nonoptimal, post-Newtonian filter. |
1304.1912 | Franco Fiorini | Franco Fiorini, P.A. Gonzalez and Yerko Vasquez | Compact extra dimensions in cosmologies with f(T) structure | 11 pages, one figure (added). Typos corrected, manuscript improved.
Additional material is contained in section IV. Accepted for publication in
Physical Review D | Phys. Rev. D 89 (2014) 024028 | 10.1103/PhysRevD.89.024028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The presence of compact extra dimensions in cosmological scenarios in the
context of f(T)-like gravities is discussed. For the case of toroidal
compactifications, the analysis is performed in an arbitrary number of extra
dimensions. Spherical topologies for the extra dimensions are then carefully
studied in six and seven spacetime dimensions, where the proper vielbein fields
responsible for the parallelization process are found.
| [
{
"created": "Sat, 6 Apr 2013 16:56:12 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Jun 2013 02:51:06 GMT",
"version": "v2"
},
{
"created": "Mon, 16 Dec 2013 15:21:44 GMT",
"version": "v3"
}
] | 2015-06-15 | [
[
"Fiorini",
"Franco",
""
],
[
"Gonzalez",
"P. A.",
""
],
[
"Vasquez",
"Yerko",
""
]
] | The presence of compact extra dimensions in cosmological scenarios in the context of f(T)-like gravities is discussed. For the case of toroidal compactifications, the analysis is performed in an arbitrary number of extra dimensions. Spherical topologies for the extra dimensions are then carefully studied in six and seven spacetime dimensions, where the proper vielbein fields responsible for the parallelization process are found. |
gr-qc/0204070 | G. Asanov | G.S. Asanov | Finslerian Anisotropic Relativistic Metric Function Obtainable under
Breakdown of Rotational Symmetry | null | null | null | null | gr-qc | null | We undertake to show how the relativistic Finslerian Metric Function (FMF)
should arise under uni-directional violation of spatial isotropy, keeping the
condition that the indicatrix (mass-shell) is a space of constant negative
curvature. By evaluating respective Finslerian tetrads, and treating them
consistently as the bases of inertial reference frame (RF), the generalized
Finslerian kinematic transformations follow in a convenient explicit form. The
concomitant Finslerian relativistic relations generalize their Lorentzian
prototypes through the presence of one characteristic parameter g, so that the
constraints on the parameter may be found in future high-precision
post-Lorentzian experiments. As the associated Finslerian Hamiltonian function
is also obtainable in a clear explicit form, convenient prospects for the
Finslerian extension of particle dynamics are also opened. Additionally, the
Finslerian extension of the general-relativistic Schwarzschild metric can
unambiguously be proposed.
| [
{
"created": "Mon, 22 Apr 2002 11:52:27 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Asanov",
"G. S.",
""
]
] | We undertake to show how the relativistic Finslerian Metric Function (FMF) should arise under uni-directional violation of spatial isotropy, keeping the condition that the indicatrix (mass-shell) is a space of constant negative curvature. By evaluating respective Finslerian tetrads, and treating them consistently as the bases of inertial reference frame (RF), the generalized Finslerian kinematic transformations follow in a convenient explicit form. The concomitant Finslerian relativistic relations generalize their Lorentzian prototypes through the presence of one characteristic parameter g, so that the constraints on the parameter may be found in future high-precision post-Lorentzian experiments. As the associated Finslerian Hamiltonian function is also obtainable in a clear explicit form, convenient prospects for the Finslerian extension of particle dynamics are also opened. Additionally, the Finslerian extension of the general-relativistic Schwarzschild metric can unambiguously be proposed. |
2204.02786 | Eduardo Am\^ancio Barbosa Oliveira | Eduardo Amancio Barbosa Oliveira (Instituto de Fisica Teorica -
Universidade Estadual Paulista) | Vacuum Energy in Modern Cosmology: an analysis of quantum field theory
in curved spaces and its application to cosmological spacetimes | 246 pages | null | 10.11606/D.76.2022.tde-06042022-100329 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The last decades have witnessed an unprecedented advancement in our knowledge
of the large scale universe. In particular, increasingly accurate cosmological
observations have allowed us to discover a form of "dark energy", which
presently dominates the expansion of the universe. On the other hand,
fundamental problems in the standard cosmological model point towards the
possibility of a primordial inflationary period. Both these expansion phases
have in common the fact that they should be governed by forms of energy with
properties much similar to those of vacuum energy of classical or quantum
fields. In the meanwhile, quantum field theory in curved spaces (QFTCS) has
proved a rich framework to analyze phenomena of a quantum nature in regimes
where spacetime curvature is relevant, but not too extreme; particularly, it
yields novel insights on the structure and dynamics of quantum vacuum. In this
dissertation, we make a thorough exposition of the fundamentals of QFTCS and
present some of its applications in cosmological spacetimes. Particular
attention is given to the construction of an empirical notion of particles
through an idealized model of particle detectors, and to the phenomenon of
particle creation in expanding FLRW spacetimes. Further, we develop the
procedure of adiabatic renormalization, and use it to compute the renormalized
stress tensor in these spacetimes. For a noninteracting scalar field in de
Sitter spaces, we find that it takes the form of a cosmological constant,
although a quantitatively self-consistent value with the background expansion
can only be found at Planckian densities. We also present a construction of a
simple inflationary model, driven by a self-interacting classical scalar field,
and show how the quantized fluctuations of this field could give rise to a
nearly scale-invariant power spectrum, like the one that is currently observed
in the CMB.
| [
{
"created": "Mon, 4 Apr 2022 20:05:31 GMT",
"version": "v1"
}
] | 2022-04-11 | [
[
"Oliveira",
"Eduardo Amancio Barbosa",
"",
"Instituto de Fisica Teorica -\n Universidade Estadual Paulista"
]
] | The last decades have witnessed an unprecedented advancement in our knowledge of the large scale universe. In particular, increasingly accurate cosmological observations have allowed us to discover a form of "dark energy", which presently dominates the expansion of the universe. On the other hand, fundamental problems in the standard cosmological model point towards the possibility of a primordial inflationary period. Both these expansion phases have in common the fact that they should be governed by forms of energy with properties much similar to those of vacuum energy of classical or quantum fields. In the meanwhile, quantum field theory in curved spaces (QFTCS) has proved a rich framework to analyze phenomena of a quantum nature in regimes where spacetime curvature is relevant, but not too extreme; particularly, it yields novel insights on the structure and dynamics of quantum vacuum. In this dissertation, we make a thorough exposition of the fundamentals of QFTCS and present some of its applications in cosmological spacetimes. Particular attention is given to the construction of an empirical notion of particles through an idealized model of particle detectors, and to the phenomenon of particle creation in expanding FLRW spacetimes. Further, we develop the procedure of adiabatic renormalization, and use it to compute the renormalized stress tensor in these spacetimes. For a noninteracting scalar field in de Sitter spaces, we find that it takes the form of a cosmological constant, although a quantitatively self-consistent value with the background expansion can only be found at Planckian densities. We also present a construction of a simple inflationary model, driven by a self-interacting classical scalar field, and show how the quantized fluctuations of this field could give rise to a nearly scale-invariant power spectrum, like the one that is currently observed in the CMB. |
1307.1331 | Abhay Ashtekar | Abhay Ashtekar | A new perspective on CP and T violation | 10 pages; `Formal Response' to the talk "Three Merry Roads to
T-Violation" by Bryan Roberts at the Workshop on Cosmology and Time, held at
the Institute for Gravitation and the Cosmos, Penn State, in April 2013 | Stud. Hist. Phil. Mod. Phys. 52, 16-20 (2015) | null | IGC/13-06/5 | gr-qc hep-th math-ph math.MP quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that the results of CP and T violation experiments can be
interpreted using a very general framework that does not require a Hilbert
space of states or linear operators to represent the symmetries or dynamics.
Analysis within this general framework brings out the aspects of quantum
mechanics that are essential for this interpretation. More importantly, should
quantum mechanics be eventually replaced by a new paradigm, this framework
could \emph{still} be used to establish violation of CP and T invariance from
the already known experimental results.
This work arose as a `formal response' to a talk "Three Merry Roads to
T-Violation" by Dr. Bryan Roberts [1]. Both talks were given at a "Workshop on
Cosmology and Time" held at Penn State in April 2013, which brought together
physicists and philosophers of science.
| [
{
"created": "Thu, 4 Jul 2013 13:58:00 GMT",
"version": "v1"
}
] | 2016-02-16 | [
[
"Ashtekar",
"Abhay",
""
]
] | It is shown that the results of CP and T violation experiments can be interpreted using a very general framework that does not require a Hilbert space of states or linear operators to represent the symmetries or dynamics. Analysis within this general framework brings out the aspects of quantum mechanics that are essential for this interpretation. More importantly, should quantum mechanics be eventually replaced by a new paradigm, this framework could \emph{still} be used to establish violation of CP and T invariance from the already known experimental results. This work arose as a `formal response' to a talk "Three Merry Roads to T-Violation" by Dr. Bryan Roberts [1]. Both talks were given at a "Workshop on Cosmology and Time" held at Penn State in April 2013, which brought together physicists and philosophers of science. |
0806.2184 | Xin Li | Zhe Chang and Xin Li | Modified Newton's gravity in Finsler Space as a possible alternative to
dark matter hypothesis | some changes have been added, to be published in Phy. Lett. B | Phys.Lett.B668:453-456,2008 | 10.1016/j.physletb.2008.09.010 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | A modified Newton's gravity is obtained as the weak field approximation of
the Einstein's equation in Finsler space. It is found that a specified Finsler
structure makes the modified Newton's gravity equivalent to the modified
Newtonian dynamics (MOND). In the framework of Finsler geometry, the flat
rotation curves of spiral galaxies can be deduced naturally without invoking
dark matter.
| [
{
"created": "Fri, 13 Jun 2008 04:57:11 GMT",
"version": "v1"
},
{
"created": "Sat, 27 Sep 2008 10:37:55 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Chang",
"Zhe",
""
],
[
"Li",
"Xin",
""
]
] | A modified Newton's gravity is obtained as the weak field approximation of the Einstein's equation in Finsler space. It is found that a specified Finsler structure makes the modified Newton's gravity equivalent to the modified Newtonian dynamics (MOND). In the framework of Finsler geometry, the flat rotation curves of spiral galaxies can be deduced naturally without invoking dark matter. |
gr-qc/9907009 | Akihiro Ishibashi | Akihiro Ishibashi and Akio Hosoya | Who's Afraid of Naked Singularities? | 25 pages, 3 figures, Accepted for publication in Phys.Rev.D | Phys.Rev. D60 (1999) 104028 | 10.1103/PhysRevD.60.104028 | YITP-99-6, TIT/HEP-414/COSMO-91 | gr-qc | null | To probe naked spacetime singularities with waves rather than with particles
we study the well-posedness of initial value problems for test scalar fields
with finite energy so that the natural function space of initial data is the
Sobolev space. In the case of static and conformally static spacetimes we
examine the essential self-adjointness of the time translation operator in the
wave equation defined in the Hilbert space. For some spacetimes the classical
singularity becomes regular if probed with waves while stronger classical
singularities remain singular. If the spacetime is regular when probed with
waves we may say that the spacetime is `globally hyperbolic.'
| [
{
"created": "Sat, 3 Jul 1999 08:55:18 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Ishibashi",
"Akihiro",
""
],
[
"Hosoya",
"Akio",
""
]
] | To probe naked spacetime singularities with waves rather than with particles we study the well-posedness of initial value problems for test scalar fields with finite energy so that the natural function space of initial data is the Sobolev space. In the case of static and conformally static spacetimes we examine the essential self-adjointness of the time translation operator in the wave equation defined in the Hilbert space. For some spacetimes the classical singularity becomes regular if probed with waves while stronger classical singularities remain singular. If the spacetime is regular when probed with waves we may say that the spacetime is `globally hyperbolic.' |
1811.02697 | Fernando Zago | Fernando Zago and Arthur Kosowsky | Quantum Particle Production Effects on Cosmic Expansion | null | Phys. Rev. D 100, 045023 (2019) | 10.1103/PhysRevD.100.045023 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum fields in cosmological spacetimes can experience particle production
due to their interaction with the expanding background. This effect is
particularly relevant for models of the very early Universe, when the energy
density generated through this process may back-react on the cosmological
expansion. Yet, these scenarios have not been fully explored due to the several
technical hurdles imposed by the back-reaction calculations. In this work we
review the basics of cosmological quantum particle production and demonstrate a
numerical algorithm to solve the back-reaction problem in regimes dominated by
particle production. As an illustration, we compute the effects of a massive
quantized scalar field on a cosmological bounce scenario, explicitly showing
that quantum particle production can cause the contracting phase to end in a
radiation crunch, or can delay the bounce. Finally, we discuss the relevance of
quantum particle production/annihilation to bounce and inflationary models of
the early Universe.
| [
{
"created": "Tue, 6 Nov 2018 22:34:39 GMT",
"version": "v1"
}
] | 2019-09-04 | [
[
"Zago",
"Fernando",
""
],
[
"Kosowsky",
"Arthur",
""
]
] | Quantum fields in cosmological spacetimes can experience particle production due to their interaction with the expanding background. This effect is particularly relevant for models of the very early Universe, when the energy density generated through this process may back-react on the cosmological expansion. Yet, these scenarios have not been fully explored due to the several technical hurdles imposed by the back-reaction calculations. In this work we review the basics of cosmological quantum particle production and demonstrate a numerical algorithm to solve the back-reaction problem in regimes dominated by particle production. As an illustration, we compute the effects of a massive quantized scalar field on a cosmological bounce scenario, explicitly showing that quantum particle production can cause the contracting phase to end in a radiation crunch, or can delay the bounce. Finally, we discuss the relevance of quantum particle production/annihilation to bounce and inflationary models of the early Universe. |
gr-qc/0611092 | Pavel Krtous | Lenka Havrdova, Pavel Krtous | Melvin universe as a limit of the C-metric | 5 pages, no figures [v2: two references added] | Gen.Rel.Grav.39:291-296,2007 | 10.1007/s10714-006-0381-3 | null | gr-qc | null | It is demonstrated that the Melvin universe representing the spacetime with a
strong 'homogeneous' electric field can by obtained from the spacetime of two
accelerated charged black holes by a suitable limiting procedure. The behavior
of various invariantly defined geometrical quantities in this limit is also
studied.
| [
{
"created": "Fri, 17 Nov 2006 04:55:27 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Jan 2007 12:22:29 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Havrdova",
"Lenka",
""
],
[
"Krtous",
"Pavel",
""
]
] | It is demonstrated that the Melvin universe representing the spacetime with a strong 'homogeneous' electric field can by obtained from the spacetime of two accelerated charged black holes by a suitable limiting procedure. The behavior of various invariantly defined geometrical quantities in this limit is also studied. |
1810.08830 | Grigoris Panotopoulos | Grigoris Panotopoulos and \'Angel Rinc\'on | Minimal Geometric Deformation in a cloud of strings | 6 pages, 3 figures, accepted for publication in EPJC | null | 10.1140/epjc/s10052-018-6321-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find new exact analytical solutions in three-dimensional gravity applying
the Minimal Geometric Deformation approach in a cloud of strings.
| [
{
"created": "Sat, 20 Oct 2018 17:27:21 GMT",
"version": "v1"
}
] | 2018-11-14 | [
[
"Panotopoulos",
"Grigoris",
""
],
[
"Rincón",
"Ángel",
""
]
] | We find new exact analytical solutions in three-dimensional gravity applying the Minimal Geometric Deformation approach in a cloud of strings. |
gr-qc/0307018 | Alexander E. Shalyt-Margolin | A.E.Shalyt-Margolin, A.Ya.Tregubovich | Generalized Uncertainty Relation in Thermodynamics | 7 pages, no figures,new references | null | null | null | gr-qc | null | It is done by introducing of an additional term proportional to the interior
energy into the standard thermodynamic uncertainty relation that leads to
existence of the lower limit of inverse temperature
| [
{
"created": "Fri, 4 Jul 2003 09:35:13 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Aug 2003 10:40:23 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Shalyt-Margolin",
"A. E.",
""
],
[
"Tregubovich",
"A. Ya.",
""
]
] | It is done by introducing of an additional term proportional to the interior energy into the standard thermodynamic uncertainty relation that leads to existence of the lower limit of inverse temperature |
1910.09564 | Shahar Hod | Shahar Hod | Strong Cosmic Censorship and the Universal Relaxation Bound | 8 pages | Nuclear Physics B 948, 114772 (2019) | 10.1016/j.nuclphysb.2019.114772 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The strong cosmic censorship conjecture, introduced by Penrose five decades
ago, asserts that, in self-consistent theories of gravity, Cauchy horizons
inside dynamically formed black holes should be unstable to remnant
perturbation fields that fall into the newly born black holes. The question of
the (in)validity of this intriguing conjecture in non-asymptotically flat
charged black-hole spacetimes has recently attracted much attention from
physicists and mathematicians. We here provide a general proof, which is based
on Bekenstein's generalized second law of thermodynamics, for the validity of
this fundamental conjecture in non-asymptotically flat de Sitter black-hole
spacetimes.
| [
{
"created": "Mon, 21 Oct 2019 18:00:06 GMT",
"version": "v1"
}
] | 2019-10-30 | [
[
"Hod",
"Shahar",
""
]
] | The strong cosmic censorship conjecture, introduced by Penrose five decades ago, asserts that, in self-consistent theories of gravity, Cauchy horizons inside dynamically formed black holes should be unstable to remnant perturbation fields that fall into the newly born black holes. The question of the (in)validity of this intriguing conjecture in non-asymptotically flat charged black-hole spacetimes has recently attracted much attention from physicists and mathematicians. We here provide a general proof, which is based on Bekenstein's generalized second law of thermodynamics, for the validity of this fundamental conjecture in non-asymptotically flat de Sitter black-hole spacetimes. |
1006.2535 | Karl Wette | LIGO Scientific Collaboration: J. Abadie, B. P. Abbott, R. Abbott, M.
Abernathy, C. Adams, R. Adhikari, P. Ajith, B. Allen, G. Allen, E. Amador
Ceron, R. S. Amin, S. B. Anderson, W. G. Anderson, M. A. Arain, M. Araya, M.
Aronsson, Y. Aso, S. Aston, D. E. Atkinson, P. Aufmuth, C. Aulbert, S. Babak,
P. Baker, S. Ballmer, D. Barker, S. Barnum, B. Barr, P. Barriga, L. Barsotti,
M. A. Barton, I. Bartos, R. Bassiri, M. Bastarrika, J. Bauchrowitz, B.
Behnke, M. Benacquista, A. Bertolini, J. Betzwieser, N. Beveridge, P. T.
Beyersdorf, I. A. Bilenko, G. Billingsley, J. Birch, R. Biswas, E. Black, J.
K. Blackburn, L. Blackburn, D. Blair, B. Bland, O. Bock, T. P. Bodiya, R.
Bondarescu, R. Bork, M. Born, S. Bose, M. Boyle, P. R. Brady, V. B.
Braginsky, J. E. Brau, J. Breyer, D. O. Bridges, M. Brinkmann, M. Britzger,
A. F. Brooks, D. A. Brown, A. Buonanno, J. Burguet--Castell, O. Burmeister,
R. L. Byer, L. Cadonati, J. B. Camp, P. Campsie, J. Cannizzo, K. C. Cannon,
J. Cao, C. Capano, S. Caride, S. Caudill, M. Cavagli\`a, C. Cepeda, T.
Chalermsongsak, E. Chalkley, P. Charlton, S. Chelkowski, Y. Chen, N.
Christensen, S. S. Y. Chua, C. T. Y. Chung, D. Clark, J. Clark, J. H.
Clayton, R. Conte, D. Cook, T. R. Corbitt, N. Cornish, C. A. Costa, D.
Coward, D. C. Coyne, J. D. E. Creighton, T. D. Creighton, A. M. Cruise, R. M.
Culter, A. Cumming, L. Cunningham, K. Dahl, S. L. Danilishin, R. Dannenberg,
K. Danzmann, K. Das, B. Daudert, G. Davies, A. Davis, E. J. Daw, T. Dayanga,
D. DeBra, J. Degallaix, V. Dergachev, R. DeRosa, R. DeSalvo, P. Devanka, S.
Dhurandhar, I. Di Palma, M. D\'iaz, F. Donovan, K. L. Dooley, E. E. Doomes,
S. Dorsher, E. S. D. Douglas, R. W. P. Drever, J. C. Driggers, J. Dueck,
J.-C. Dumas, T. Eberle, M. Edgar, M. Edwards, A. Effler, P. Ehrens, R. Engel,
T. Etzel, M. Evans, T. Evans, S. Fairhurst, Y. Fan, B. F. Farr, D. Fazi, H.
Fehrmann, D. Feldbaum, L. S. Finn, M. Flanigan, K. Flasch, S. Foley, C.
Forrest, E. Forsi, N. Fotopoulos, M. Frede, M. Frei, Z. Frei, A. Freise, R.
Frey, T. T. Fricke, D. Friedrich, P. Fritschel, V. V. Frolov, P. Fulda, M.
Fyffe, J. A. Garofoli, I. Gholami, S. Ghosh, J. A. Giaime, S. Giampanis, K.
D. Giardina, C. Gill, E. Goetz, L. M. Goggin, G. Gonz\'alez, M. L.
Gorodetsky, S. Go{\ss}ler, C. Graef, A. Grant, S. Gras, C. Gray, R. J. S.
Greenhalgh, A. M. Gretarsson, R. Grosso, H. Grote, S. Grunewald, E. K.
Gustafson, R. Gustafson, B. Hage, P. Hall, J. M. Hallam, D. Hammer, G.
Hammond, J. Hanks, C. Hanna, J. Hanson, J. Harms, G. M. Harry, I. W. Harry,
E. D. Harstad, K. Haughian, K. Hayama, J. Heefner, I. S. Heng, A.
Heptonstall, M. Hewitson, S. Hild, E. Hirose, D. Hoak, K. A. Hodge, K. Holt,
D. J. Hosken, J. Hough, E. Howell, D. Hoyland, B. Hughey, S. Husa, S. H.
Huttner, T. Huynh--Dinh, D. R. Ingram, R. Inta, T. Isogai, A. Ivanov, W. W.
Johnson, D. I. Jones, G. Jones, R. Jones, L. Ju, P. Kalmus, V. Kalogera, S.
Kandhasamy, J. Kanner, E. Katsavounidis, K. Kawabe, S. Kawamura, F. Kawazoe,
W. Kells, D. G. Keppel, A. Khalaidovski, F. Y. Khalili, E. A. Khazanov, H.
Kim, P. J. King, D. L. Kinzel, J. S. Kissel, S. Klimenko, V. Kondrashov, R.
Kopparapu, S. Koranda, D. Kozak, T. Krause, V. Kringel, S. Krishnamurthy, B.
Krishnan, G. Kuehn, J. Kullman, R. Kumar, P. Kwee, M. Landry, M. Lang, B.
Lantz, N. Lastzka, A. Lazzarini, P. Leaci, J. Leong, I. Leonor, J. Li, H.
Lin, P. E. Lindquist, N. A. Lockerbie, D. Lodhia, M. Lormand, P. Lu, J. Luan,
M. Lubinski, A. Lucianetti, H. L\"uck, A. Lundgren, B. Machenschalk, M.
MacInnis, M. Mageswaran, K. Mailand, C. Mak, I. Mandel, V. Mandic, S.
M\'arka, Z. M\'arka, E. Maros, I. W. Martin, R. M. Martin, J. N. Marx, K.
Mason, F. Matichard, L. Matone, R. A. Matzner, N. Mavalvala, R. McCarthy, D.
E. McClelland, S. C. McGuire, G. McIntyre, G. McIvor, D. J. A. McKechan, G.
Meadors, M. Mehmet, T. Meier, A. Melatos, A. C. Melissinos, G. Mendell, D. F.
Men\'endez, R. A. Mercer, L. Merill, S. Meshkov, C. Messenger, M. S. Meyer,
H. Miao, J. Miller, Y. Mino, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R.
Mittleman, B. Moe, S. D. Mohanty, S. R. P. Mohapatra, D. Moraru, G. Moreno,
T. Morioka, K. Mors, K. Mossavi, C. MowLowry, G. Mueller, S. Mukherjee, A.
Mullavey, H. M\"uller-Ebhardt, J. Munch, P. G. Murray, T. Nash, R. Nawrodt,
J. Nelson, G. Newton, A. Nishizawa, D. Nolting, E. Ochsner, J. O'Dell, G. H.
Ogin, R. G. Oldenburg, B. O'Reilly, R. O'Shaughnessy, C. Osthelder, D. J.
Ottaway, R. S. Ottens, H. Overmier, B. J. Owen, A. Page, Y. Pan, C. Pankow,
M. A. Papa, M. Pareja, P. Patel, M. Pedraza, L. Pekowsky, S. Penn, C.
Peralta, A. Perreca, M. Pickenpack, I. M. Pinto, M. Pitkin, H. J. Pletsch, M.
V. Plissi, F. Postiglione, V. Predoi, L. R. Price, M. Prijatelj, M. Principe,
R. Prix, L. Prokhorov, O. Puncken, V. Quetschke, F. J. Raab, T. Radke, H.
Radkins, P. Raffai, M. Rakhmanov, B. Rankins, V. Raymond, C. M. Reed, T.
Reed, S. Reid, D. H. Reitze, R. Riesen, K. Riles, P. Roberts, N. A.
Robertson, C. Robinson, E. L. Robinson, S. Roddy, C. R\"over, J. Rollins, J.
D. Romano, J. H. Romie, S. Rowan, A. R\"udiger, K. Ryan, S. Sakata, M.
Sakosky, F. Salemi, L. Sammut, L. Sancho de la Jordana, V. Sandberg, V.
Sannibale, L. Santamar\'ia, G. Santostasi, S. Saraf, B. S. Sathyaprakash, S.
Sato, M. Satterthwaite, P. R. Saulson, R. Savage, R. Schilling, R. Schnabel,
R. Schofield, B. Schulz, B. F. Schutz, P. Schwinberg, J. Scott, S. M. Scott,
A. C. Searle, F. Seifert, D. Sellers, A. S. Sengupta, A. Sergeev, D.
Shaddock, B. Shapiro, P. Shawhan, D. H. Shoemaker, A. Sibley, X. Siemens, D.
Sigg, A. Singer, A. M. Sintes, G. Skelton, B. J. J. Slagmolen, J. Slutsky, J.
R. Smith, M. R. Smith, N. D. Smith, K. Somiya, B. Sorazu, F. C. Speirits, A.
J. Stein, L. C. Stein, S. Steinlechner, S. Steplewski, A. Stochino, R. Stone,
K. A. Strain, S. Strigin, A. Stroeer, A. L. Stuver, T. Z. Summerscales, M.
Sung, S. Susmithan, P. J. Sutton, D. Talukder, D. B. Tanner, S. P. Tarabrin,
J. R. Taylor, R. Taylor, P. Thomas, K. A. Thorne, K. S. Thorne, E. Thrane, A.
Th\"uring, C. Titsler, K. V. Tokmakov, C. Torres, C. I. Torrie, G. Traylor,
M. Trias, K. Tseng, D. Ugolini, K. Urbanek, H. Vahlbruch, B. Vaishnav, M.
Vallisneri, C. Van Den Broeck, M. V. van der Sluys, A. A. van Veggel, S.
Vass, R. Vaulin, A. Vecchio, J. Veitch, P. J. Veitch, C. Veltkamp, A. Villar,
C. Vorvick, S. P. Vyachanin, S. J. Waldman, L. Wallace, A. Wanner, R. L.
Ward, P. Wei, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, S. Wen, P.
Wessels, M. West, T. Westphal, K. Wette, J. T. Whelan, S. E. Whitcomb, D. J.
White, B. F. Whiting, C. Wilkinson, P. A. Willems, L. Williams, B. Willke, L.
Winkelmann, W. Winkler, C. C. Wipf, A. G. Wiseman, G. Woan, R. Wooley, J.
Worden, I. Yakushin, H. Yamamoto, K. Yamamoto, D. Yeaton-Massey, S. Yoshida,
P. P. Yu, M. Zanolin, L. Zhang, Z. Zhang, C. Zhao, N. Zotov, M. E. Zucker, J.
Zweizig | First search for gravitational waves from the youngest known neutron
star | 26 pages, 5 figures | Astrophys.J.722:1504-1513,2010 | 10.1088/0004-637X/722/2/1504 | LIGO-P1000028-v7 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a search for periodic gravitational waves from the neutron star in
the supernova remnant Cassiopeia A. The search coherently analyzes data in a
12-day interval taken from the fifth science run of the Laser Interferometer
Gravitational-Wave Observatory. It searches gravitational wave frequencies from
100 to 300 Hz, and covers a wide range of first and second frequency
derivatives appropriate for the age of the remnant and for different spin-down
mechanisms. No gravitational wave signal was detected. Within the range of
search frequencies, we set 95% confidence upper limits of 0.7--1.2e-24 on the
intrinsic gravitational wave strain, 0.4--4e-4 on the equatorial ellipticity of
the neutron star, and 0.005--0.14 on the amplitude of r-mode oscillations of
the neutron star. These direct upper limits beat indirect limits derived from
energy conservation and enter the range of theoretical predictions involving
crystalline exotic matter or runaway r-modes. This is the first gravitational
wave search to present upper limits on r-modes.
| [
{
"created": "Sun, 13 Jun 2010 13:38:05 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Sep 2010 14:27:12 GMT",
"version": "v2"
}
] | 2014-11-21 | [
[
"LIGO Scientific Collaboration",
"",
""
],
[
"Abadie",
"J.",
""
],
[
"Abbott",
"B. P.",
""
],
[
"Abbott",
"R.",
""
],
[
"Abernathy",
"M.",
""
],
[
"Adams",
"C.",
""
],
[
"Adhikari",
"R.",
""
],
[
"A... | We present a search for periodic gravitational waves from the neutron star in the supernova remnant Cassiopeia A. The search coherently analyzes data in a 12-day interval taken from the fifth science run of the Laser Interferometer Gravitational-Wave Observatory. It searches gravitational wave frequencies from 100 to 300 Hz, and covers a wide range of first and second frequency derivatives appropriate for the age of the remnant and for different spin-down mechanisms. No gravitational wave signal was detected. Within the range of search frequencies, we set 95% confidence upper limits of 0.7--1.2e-24 on the intrinsic gravitational wave strain, 0.4--4e-4 on the equatorial ellipticity of the neutron star, and 0.005--0.14 on the amplitude of r-mode oscillations of the neutron star. These direct upper limits beat indirect limits derived from energy conservation and enter the range of theoretical predictions involving crystalline exotic matter or runaway r-modes. This is the first gravitational wave search to present upper limits on r-modes. |
gr-qc/0204014 | Gobinda Mujumder | A. Bhadra (University of North Bengal) | General relativity limit of the scalar-tensor theories for traceless
matter field | 9 pages, no figures, Latex | null | null | null | gr-qc | null | $\omega(\phi) \to \infty$ limit of scalar tensor theories are studied for
traceless matter source. It is shown that the limit $\omega(\phi) \to \infty$
does not reduce a scalar tensor theory to general relativity.
An exact radiation solution of scalar tensor cosmology under Nordtvedt
conditions is obtained for flat Friedmann universe.
| [
{
"created": "Wed, 3 Apr 2002 08:31:52 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Bhadra",
"A.",
"",
"University of North Bengal"
]
] | $\omega(\phi) \to \infty$ limit of scalar tensor theories are studied for traceless matter source. It is shown that the limit $\omega(\phi) \to \infty$ does not reduce a scalar tensor theory to general relativity. An exact radiation solution of scalar tensor cosmology under Nordtvedt conditions is obtained for flat Friedmann universe. |
2003.04928 | Paola Carolina Moreira Delgado | P. C. M. Delgado and N. Pinto-Neto | Cosmological models with asymmetric quantum bounces | 10 pages, 6 figures; correction in section III B, main results
unchanged; references added. This is an author-created, un-copyedited version
of an article published in Classical and Quantum Gravity. IOP Publishing Ltd
is not responsible for any errors or omissions in this version of the
manuscript or any version derived from it. The Version of Record is available
online at the DOI link below | Class. Quantum Grav. 37 125002 (2020) | 10.1088/1361-6382/ab8bb8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In quantum cosmology, one has to select a specific wave function solution of
the quantum state equations under consideration in order to obtain concrete
results. The simplest choices have been already explored, in different
frameworks, yielding, in many cases, quantum bounces. As there is no
consensually established boundary condition proposal in quantum cosmology, we
investigate the consequences of enlarging known sets of initial wave functions
of the universe, in the specific framework of the Wheeler-DeWitt equation
interpreted along the lines of the de Broglie-Bohm quantum theory, on the
possible quantum bounce solutions which emerge from them. In particular, we
show that many asymmetric quantum bounces are obtained, which may incorporate
non-trivial back-reaction mechanisms, as quantum particle production around the
bounce, in the quantum background itself. In particular, the old hypothesis
that our expanding universe might have arisen from quantum fluctuations of a
fundamental quantum flat space-time is recovered, within a different and yet
unexplored perspective.
| [
{
"created": "Tue, 10 Mar 2020 18:52:02 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Sep 2021 16:57:00 GMT",
"version": "v2"
}
] | 2021-09-06 | [
[
"Delgado",
"P. C. M.",
""
],
[
"Pinto-Neto",
"N.",
""
]
] | In quantum cosmology, one has to select a specific wave function solution of the quantum state equations under consideration in order to obtain concrete results. The simplest choices have been already explored, in different frameworks, yielding, in many cases, quantum bounces. As there is no consensually established boundary condition proposal in quantum cosmology, we investigate the consequences of enlarging known sets of initial wave functions of the universe, in the specific framework of the Wheeler-DeWitt equation interpreted along the lines of the de Broglie-Bohm quantum theory, on the possible quantum bounce solutions which emerge from them. In particular, we show that many asymmetric quantum bounces are obtained, which may incorporate non-trivial back-reaction mechanisms, as quantum particle production around the bounce, in the quantum background itself. In particular, the old hypothesis that our expanding universe might have arisen from quantum fluctuations of a fundamental quantum flat space-time is recovered, within a different and yet unexplored perspective. |
gr-qc/0611088 | Alan D. Rendall | Alan D. Rendall | Late-time oscillatory behaviour for self-gravitating scalar fields | 17 pages, additional references | Class.Quant.Grav.24:667-678,2007 | 10.1088/0264-9381/24/3/010 | AEI-2006-082 | gr-qc | null | This paper investigates the late-time behaviour of certain cosmological
models where oscillations play an essential role. Rigorous results are proved
on the asymptotics of homogeneous and isotropic spacetimes with a linear
massive scalar field as source. Various generalizations are obtained for
nonlinear massive scalar fields, $k$-essence models and $f(R)$ gravity. The
effect of adding ordinary matter is discussed as is the case of nonlinear
scalar fields whose potential has a degenerate zero.
| [
{
"created": "Thu, 16 Nov 2006 15:21:11 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Nov 2006 13:04:27 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Rendall",
"Alan D.",
""
]
] | This paper investigates the late-time behaviour of certain cosmological models where oscillations play an essential role. Rigorous results are proved on the asymptotics of homogeneous and isotropic spacetimes with a linear massive scalar field as source. Various generalizations are obtained for nonlinear massive scalar fields, $k$-essence models and $f(R)$ gravity. The effect of adding ordinary matter is discussed as is the case of nonlinear scalar fields whose potential has a degenerate zero. |
gr-qc/0505033 | Thomas Thiemann | Johannes Brunnemann, Thomas Thiemann | Unboundedness of Triad -- Like Operators in Loop Quantum Gravity | 57 pages, 19 figures | Class.Quant.Grav. 23 (2006) 1429-1484 | 10.1088/0264-9381/23/5/002 | AEI-2005-099 | gr-qc astro-ph hep-th math-ph math.MP | null | In this paper we deliver the proofs for the claims, made in a companion
paper, concerning the avoidance of cosmological curvature singularities in in
full Loop Quantum Gravity (LQG).
| [
{
"created": "Sun, 8 May 2005 20:55:02 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Brunnemann",
"Johannes",
""
],
[
"Thiemann",
"Thomas",
""
]
] | In this paper we deliver the proofs for the claims, made in a companion paper, concerning the avoidance of cosmological curvature singularities in in full Loop Quantum Gravity (LQG). |
0909.0487 | L\'aszl\'o \'A Gergely | L\'aszl\'o \'A. Gergely, Peter L. Biermann, Bal\'azs Mik\'oczi,
Zolt\'an Keresztes | Renormalized spin coefficients in the accumulated orbital phase for
unequal mass black hole binaries | 10 pages, to appear in Class. Quantum Grav. GWDAW13 Proceedings
Special Issue, v2: no typos conjecture | Class.Quant.Grav.26:204006,2009 | 10.1088/0264-9381/26/20/204006 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze galactic black hole mergers and their emitted gravitational waves.
Such mergers have typically unequal masses with mass ratio of the order 1/10.
The emitted gravitational waves carry the inprint of spins and mass quadrupoles
of the binary components. Among these contributions, we consider here the
quasi-precessional evolution of the spins. A method of taking into account
these third post-Newtonian (3PN) effects by renormalizing (redefining) the 1.5
PN and 2PN accurate spin contributions to the accumulated orbital phase is
developed.
| [
{
"created": "Wed, 2 Sep 2009 18:14:40 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Sep 2009 20:37:59 GMT",
"version": "v2"
}
] | 2009-11-18 | [
[
"Gergely",
"László Á.",
""
],
[
"Biermann",
"Peter L.",
""
],
[
"Mikóczi",
"Balázs",
""
],
[
"Keresztes",
"Zoltán",
""
]
] | We analyze galactic black hole mergers and their emitted gravitational waves. Such mergers have typically unequal masses with mass ratio of the order 1/10. The emitted gravitational waves carry the inprint of spins and mass quadrupoles of the binary components. Among these contributions, we consider here the quasi-precessional evolution of the spins. A method of taking into account these third post-Newtonian (3PN) effects by renormalizing (redefining) the 1.5 PN and 2PN accurate spin contributions to the accumulated orbital phase is developed. |
2405.18502 | Jarmo M\"akel\"a Dr. | Jarmo M\"akel\"a | A Possible Quantum Effect of Gravitation | 23 pages, no figures. Accepted for publication in the General
Relativity and Gravitation. Comments welcome! | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Beginning from the standard Arnowitt-Deser-Misner (ADM) formulation of
general relativity we construct a tentative model of quantum gravity from the
point of view of an observer with constant proper acceleration, just outside of
a horizon of spacetime. In addition of producing the standard results of
black-hole thermodynamics, our model makes an entirely new prediction that
there is a certain upper bound for the energies of massive particles. For
protons, for instance, this upper bound is around $1.1\times 10^{21}eV$. The
result is interesting, because this energy is roughly of the same order of
magnitude as are the highest energies ever measured for protons in cosmic rays.
| [
{
"created": "Tue, 28 May 2024 18:14:02 GMT",
"version": "v1"
}
] | 2024-05-30 | [
[
"Mäkelä",
"Jarmo",
""
]
] | Beginning from the standard Arnowitt-Deser-Misner (ADM) formulation of general relativity we construct a tentative model of quantum gravity from the point of view of an observer with constant proper acceleration, just outside of a horizon of spacetime. In addition of producing the standard results of black-hole thermodynamics, our model makes an entirely new prediction that there is a certain upper bound for the energies of massive particles. For protons, for instance, this upper bound is around $1.1\times 10^{21}eV$. The result is interesting, because this energy is roughly of the same order of magnitude as are the highest energies ever measured for protons in cosmic rays. |
gr-qc/9411016 | Jesus Barbero | J. Fernando Barbero | Solving the Constraints of General Relativity | 8 pages, LATEX, no figures, Preprint CGPG-94/11-3 | Class.Quant.Grav.12:L5-L10,1995 | 10.1088/0264-9381/12/2/001 | null | gr-qc | null | I show in this letter that it is possible to solve some of the constraints of
the $SO(3)$-ADM formalism for general relativity by using an approach similar
to the one introduced by Capovilla, Dell and Jacobson to solve the vector and
scalar constraints in the Ashtekar variables framework. I discuss the
advantages of using the ADM formalism and compare the result with similar
proposals for different Hamiltonian formulations of general relativity.
| [
{
"created": "Mon, 7 Nov 1994 20:58:12 GMT",
"version": "v1"
}
] | 2017-03-24 | [
[
"Barbero",
"J. Fernando",
""
]
] | I show in this letter that it is possible to solve some of the constraints of the $SO(3)$-ADM formalism for general relativity by using an approach similar to the one introduced by Capovilla, Dell and Jacobson to solve the vector and scalar constraints in the Ashtekar variables framework. I discuss the advantages of using the ADM formalism and compare the result with similar proposals for different Hamiltonian formulations of general relativity. |
1306.6216 | Adam Chudecki Dr | Adam Chudecki | Null Killing vectors and geometry of null strings in Einstein spaces | null | Gen. Relativ. Gravit. (2014) 46: 1714 | 10.1007/s10714-014-1714-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Einstein complex spacetimes admitting null Killing or null homothetic Killing
vectors are studied. These vectors define totally null and geodesic 2-surfaces
called the null strings or twistor surfaces. Geometric properties of these null
strings are discussed. It is shown, that spaces considered are hyperheavenly
spaces (HH-spaces) or, if one of the parts of the Weyl tensor vanishes,
heavenly spaces (H-spaces). The explicit complex metrics admitting null Killing
vectors are found. Some Lorentzian and ultrahyperbolic slices of these metrics
are discussed.
| [
{
"created": "Wed, 26 Jun 2013 12:14:05 GMT",
"version": "v1"
}
] | 2014-04-17 | [
[
"Chudecki",
"Adam",
""
]
] | Einstein complex spacetimes admitting null Killing or null homothetic Killing vectors are studied. These vectors define totally null and geodesic 2-surfaces called the null strings or twistor surfaces. Geometric properties of these null strings are discussed. It is shown, that spaces considered are hyperheavenly spaces (HH-spaces) or, if one of the parts of the Weyl tensor vanishes, heavenly spaces (H-spaces). The explicit complex metrics admitting null Killing vectors are found. Some Lorentzian and ultrahyperbolic slices of these metrics are discussed. |
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