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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/0311092 | Aidan Burch | Aidan Burch | Histories Electromagnetism | 26 pages | J.Math.Phys. 45 (2004) 2153-2170 | 10.1063/1.1723702 | Imperial/TP/03-4/4 | gr-qc quant-ph | null | Working within the HPO (History Projection Operator) Consistent Histories
formalism, we follow the work of Savvidou on (scalar) field theory and that of
Savvidou and Anastopolous on (first-class) constrained systems to write a
histories theory (both classical and quantum) of Electromagnetism. We focus
particularly on the foliation-dependence of the histories phase space/Hilbert
space and the action thereon of the two Poincare groups that arise in histories
field theory. We quantise in the spirit of the Dirac scheme for constrained
systems.
| [
{
"created": "Fri, 28 Nov 2003 12:44:08 GMT",
"version": "v1"
},
{
"created": "Sat, 29 Nov 2003 13:35:13 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Burch",
"Aidan",
""
]
] | Working within the HPO (History Projection Operator) Consistent Histories formalism, we follow the work of Savvidou on (scalar) field theory and that of Savvidou and Anastopolous on (first-class) constrained systems to write a histories theory (both classical and quantum) of Electromagnetism. We focus particularly on the foliation-dependence of the histories phase space/Hilbert space and the action thereon of the two Poincare groups that arise in histories field theory. We quantise in the spirit of the Dirac scheme for constrained systems. |
2405.18277 | Indranil Chakraborty | Subhajit Barman, Indranil Chakraborty, and Sajal Mukherjee | Signatures of gravitational wave memory in the radiative process of
entangled quantum probes | 22 pages, 5 figures, comments are welcome | null | null | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, we examine entangled quantum probes in geodesic trajectories
in a background with gravitational wave (GW) burst. In particular, these
quantum probes are prepared initially either in the symmetric or anti-symmetric
Bell's states and we study the radiative process as the GW burst passes. Our
considered GW burst backgrounds have the profiles of -- Heaviside-theta,
$tanh$, Gaussian, and $sech$-squared functions respectively. The first two
burst profiles have an asymmetric nature and thus result in non-zero
gravitational wave memory. Whereas, for the last two symmetric profiles there
is no asymptotic memory. For eternal switching, our observations suggest that
the collective transition rate for the entangled probes due to symmetric GW
bursts remains the same as obtained in the flat space. Whereas, for asymmetric
bursts with memory, there is a finite change, indicating a direct possibility
to distinguish between the two above-mentioned scenarios. We also consider
finite switching in terms of Gaussian functions and observe characteristic
differences in the radiative process between the GW backgrounds with and
without memory. Notably, if the Gaussian switching is peaked much later
compared to the passing of GW, only memory profiles contribute to the radiative
process. We further discuss the physical implications of our findings.
| [
{
"created": "Tue, 28 May 2024 15:26:38 GMT",
"version": "v1"
}
] | 2024-05-29 | [
[
"Barman",
"Subhajit",
""
],
[
"Chakraborty",
"Indranil",
""
],
[
"Mukherjee",
"Sajal",
""
]
] | In this article, we examine entangled quantum probes in geodesic trajectories in a background with gravitational wave (GW) burst. In particular, these quantum probes are prepared initially either in the symmetric or anti-symmetric Bell's states and we study the radiative process as the GW burst passes. Our considered GW burst backgrounds have the profiles of -- Heaviside-theta, $tanh$, Gaussian, and $sech$-squared functions respectively. The first two burst profiles have an asymmetric nature and thus result in non-zero gravitational wave memory. Whereas, for the last two symmetric profiles there is no asymptotic memory. For eternal switching, our observations suggest that the collective transition rate for the entangled probes due to symmetric GW bursts remains the same as obtained in the flat space. Whereas, for asymmetric bursts with memory, there is a finite change, indicating a direct possibility to distinguish between the two above-mentioned scenarios. We also consider finite switching in terms of Gaussian functions and observe characteristic differences in the radiative process between the GW backgrounds with and without memory. Notably, if the Gaussian switching is peaked much later compared to the passing of GW, only memory profiles contribute to the radiative process. We further discuss the physical implications of our findings. |
0805.4400 | Baojiu Li | Baojiu Li, John D. Barrow, David F. Mota, HongSheng Zhao | Testing Alternative Theories of Dark Matter with the CMB | 14 pages, 8 figures | Phys.Rev.D78:064021,2008 | 10.1103/PhysRevD.78.064021 | null | gr-qc astro-ph hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a method to study and constrain modified gravity theories for dark
matter using CMB temperature anisotropies and polarization. We assume that the
theories considered here have already passed the matter power-spectrum test of
large-scale structure. With this requirement met, we show that a modified
gravity theory can be specified by parametrizing the time evolution of its
dark-matter density contrast, which is completely controlled by the dark matter
stress history. We calculate how the stress history with a given
parametrization affects the CMB observables, and a qualitative discussion of
the physical effects involved is supplemented with numerical examples. It is
found that, in general, alternative gravity theories can be efficiently
constrained by the CMB temperature and polarization spectra. There exist,
however, special cases where modified gravity cannot be distinguished from the
CDM model even by using both CMB and matter power spectrum observations, nor
can they be efficiently restricted by other observables in perturbed
cosmologies. Our results show how the stress properties of dark matter, which
determine the evolutions of both density perturbations and the gravitational
potential, can be effectively investigated using just the general conservation
equations and without assuming any specific theoretical gravitational theory
within a wide class.
| [
{
"created": "Wed, 28 May 2008 18:42:19 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Li",
"Baojiu",
""
],
[
"Barrow",
"John D.",
""
],
[
"Mota",
"David F.",
""
],
[
"Zhao",
"HongSheng",
""
]
] | We propose a method to study and constrain modified gravity theories for dark matter using CMB temperature anisotropies and polarization. We assume that the theories considered here have already passed the matter power-spectrum test of large-scale structure. With this requirement met, we show that a modified gravity theory can be specified by parametrizing the time evolution of its dark-matter density contrast, which is completely controlled by the dark matter stress history. We calculate how the stress history with a given parametrization affects the CMB observables, and a qualitative discussion of the physical effects involved is supplemented with numerical examples. It is found that, in general, alternative gravity theories can be efficiently constrained by the CMB temperature and polarization spectra. There exist, however, special cases where modified gravity cannot be distinguished from the CDM model even by using both CMB and matter power spectrum observations, nor can they be efficiently restricted by other observables in perturbed cosmologies. Our results show how the stress properties of dark matter, which determine the evolutions of both density perturbations and the gravitational potential, can be effectively investigated using just the general conservation equations and without assuming any specific theoretical gravitational theory within a wide class. |
2007.05486 | Peter K.F. Kuhfittig | Peter K.F. Kuhfittig | Traversable wormholes and the Brouwer fixed-point theorem | 6 pages, 1 figure | J. Appl. Math. and Phys. (JAMP), vol. 8, 1263-1268 (2020) | 10.4236/jamp.2020.87096 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Brouwer fixed-point theorem in topology states that for any continuous
mapping $f$ on a compact convex set into itself admits a fixed point, i.e., a
point $x_0$ such that $f(x_0)=x_0$. Under certain conditions, this fixed point
corresponds to the throat of a traversable wormhole, i.e., $b(r_0)=r_0$ for the
shape function $b=b(r)$. The possible existence of wormholes can therefore be
deduced from purely mathematical considerations without going beyond the
existing physical requirements.
| [
{
"created": "Fri, 10 Jul 2020 17:06:43 GMT",
"version": "v1"
},
{
"created": "Sat, 25 Sep 2021 17:41:12 GMT",
"version": "v2"
}
] | 2021-09-28 | [
[
"Kuhfittig",
"Peter K. F.",
""
]
] | The Brouwer fixed-point theorem in topology states that for any continuous mapping $f$ on a compact convex set into itself admits a fixed point, i.e., a point $x_0$ such that $f(x_0)=x_0$. Under certain conditions, this fixed point corresponds to the throat of a traversable wormhole, i.e., $b(r_0)=r_0$ for the shape function $b=b(r)$. The possible existence of wormholes can therefore be deduced from purely mathematical considerations without going beyond the existing physical requirements. |
1003.4961 | Slava G. Turyshev | Slava G. Turyshev, William Farr, William M. Folkner, Andre R. Girerd,
Hamid Hemmati, Thomas W. Murphy, Jr., James G. Williams, and John J. Degnan | Advancing Tests of Relativistic Gravity via Laser Ranging to Phobos | 25 pages, 10 figures, 9 tables | Experimental Astronomy 28, 209-249 (2010) | 10.1007/s10686-010-9199-9 | null | gr-qc physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Phobos Laser Ranging (PLR) is a concept for a space mission designed to
advance tests of relativistic gravity in the solar system. PLR's primary
objective is to measure the curvature of space around the Sun, represented by
the Eddington parameter $\gamma$, with an accuracy of two parts in $10^7$,
thereby improving today's best result by two orders of magnitude. Other mission
goals include measurements of the time-rate-of-change of the gravitational
constant, $G$ and of the gravitational inverse square law at 1.5 AU
distances--with up to two orders-of-magnitude improvement for each. The science
parameters will be estimated using laser ranging measurements of the distance
between an Earth station and an active laser transponder on Phobos capable of
reaching mm-level range resolution. A transponder on Phobos sending 0.25 mJ, 10
ps pulses at 1 kHz, and receiving asynchronous 1 kHz pulses from earth via a 12
cm aperture will permit links that even at maximum range will exceed a photon
per second. A total measurement precision of 50 ps demands a few hundred
photons to average to 1 mm (3.3 ps) range precision. Existing satellite laser
ranging (SLR) facilities--with appropriate augmentation--may be able to
participate in PLR. Since Phobos' orbital period is about 8 hours, each
observatory is guaranteed visibility of the Phobos instrument every Earth day.
Given the current technology readiness level, PLR could be started in 2011 for
launch in 2016 for 3 years of science operations. We discuss the PLR's science
objectives, instrument, and mission design. We also present the details of
science simulations performed to support the mission's primary objectives.
| [
{
"created": "Thu, 25 Mar 2010 17:50:05 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Sep 2010 06:14:38 GMT",
"version": "v2"
}
] | 2012-08-27 | [
[
"Turyshev",
"Slava G.",
""
],
[
"Farr",
"William",
""
],
[
"Folkner",
"William M.",
""
],
[
"Girerd",
"Andre R.",
""
],
[
"Hemmati",
"Hamid",
""
],
[
"Murphy,",
"Thomas W.",
"Jr."
],
[
"Williams",
"James G.",
... | Phobos Laser Ranging (PLR) is a concept for a space mission designed to advance tests of relativistic gravity in the solar system. PLR's primary objective is to measure the curvature of space around the Sun, represented by the Eddington parameter $\gamma$, with an accuracy of two parts in $10^7$, thereby improving today's best result by two orders of magnitude. Other mission goals include measurements of the time-rate-of-change of the gravitational constant, $G$ and of the gravitational inverse square law at 1.5 AU distances--with up to two orders-of-magnitude improvement for each. The science parameters will be estimated using laser ranging measurements of the distance between an Earth station and an active laser transponder on Phobos capable of reaching mm-level range resolution. A transponder on Phobos sending 0.25 mJ, 10 ps pulses at 1 kHz, and receiving asynchronous 1 kHz pulses from earth via a 12 cm aperture will permit links that even at maximum range will exceed a photon per second. A total measurement precision of 50 ps demands a few hundred photons to average to 1 mm (3.3 ps) range precision. Existing satellite laser ranging (SLR) facilities--with appropriate augmentation--may be able to participate in PLR. Since Phobos' orbital period is about 8 hours, each observatory is guaranteed visibility of the Phobos instrument every Earth day. Given the current technology readiness level, PLR could be started in 2011 for launch in 2016 for 3 years of science operations. We discuss the PLR's science objectives, instrument, and mission design. We also present the details of science simulations performed to support the mission's primary objectives. |
gr-qc/0504062 | Ludovico Carbone | S. Vitale (for LTP Collaboration) | The LTP Experiment on the LISA Pathfinder Mission | Submitted to Classical and Quantum Gravity, Proceedings of the 5th
LISA Symposium, ESTEC, Noordwijk, The Netherlands, 12-15 July 2004 | null | null | null | gr-qc | null | We report on the development of the LISA Technology Package (LTP) experiment
that will fly on board the LISA Pathfinder mission of the European Space Agency
in 2008. We first summarize the science rationale of the experiment aimed at
showing the operational feasibility of the so called Transverse-Traceless
coordinate frame within the accuracy needed for LISA. We then show briefly the
basic features of the instrument and we finally discuss its projected
sensitivity and the extrapolation of its results to LISA.
| [
{
"created": "Thu, 14 Apr 2005 10:45:13 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Vitale",
"S.",
"",
"for LTP Collaboration"
]
] | We report on the development of the LISA Technology Package (LTP) experiment that will fly on board the LISA Pathfinder mission of the European Space Agency in 2008. We first summarize the science rationale of the experiment aimed at showing the operational feasibility of the so called Transverse-Traceless coordinate frame within the accuracy needed for LISA. We then show briefly the basic features of the instrument and we finally discuss its projected sensitivity and the extrapolation of its results to LISA. |
gr-qc/0001037 | Simonetta Frittelli | Simonetta Frittelli, Thomas P. Kling and Ezra T. Newman | Spacetime perspective of Schwarzschild lensing | 22 pages, 6 figures, to appear in Phys. Rev. D | Phys.Rev. D61 (2000) 064021 | 10.1103/PhysRevD.61.064021 | null | gr-qc | null | We propose a definition of an exact lens equation without reference to a
background spacetime, and construct the exact lens equation explicitly in the
case of Schwarzschild spacetime. For the Schwarzschild case, we give exact
expressions for the angular-diameter distance to the sources as well as for the
magnification factor and time of arrival of the images. We compare the exact
lens equation with the standard lens equation, derived under the
thin-lens-weak-field assumption (where the light rays are geodesics of the
background with sharp bending in the lens plane, and the gravitational field is
weak), and verify the fact that the standard weak-field thin-lens equation is
inadequate at small impact parameter. We show that the second-order correction
to the weak-field thin-lens equation is inaccurate as well. Finally, we compare
the exact lens equation with the recently proposed strong-field thin-lens
equation, obtained under the assumption of straight paths but without the small
angle approximation, i.e., with allowed large bending angles. We show that the
strong-field thin-lens equation is remarkably accurate, even for lightrays that
take several turns around the lens before reaching the observer.
| [
{
"created": "Thu, 13 Jan 2000 21:39:21 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Frittelli",
"Simonetta",
""
],
[
"Kling",
"Thomas P.",
""
],
[
"Newman",
"Ezra T.",
""
]
] | We propose a definition of an exact lens equation without reference to a background spacetime, and construct the exact lens equation explicitly in the case of Schwarzschild spacetime. For the Schwarzschild case, we give exact expressions for the angular-diameter distance to the sources as well as for the magnification factor and time of arrival of the images. We compare the exact lens equation with the standard lens equation, derived under the thin-lens-weak-field assumption (where the light rays are geodesics of the background with sharp bending in the lens plane, and the gravitational field is weak), and verify the fact that the standard weak-field thin-lens equation is inadequate at small impact parameter. We show that the second-order correction to the weak-field thin-lens equation is inaccurate as well. Finally, we compare the exact lens equation with the recently proposed strong-field thin-lens equation, obtained under the assumption of straight paths but without the small angle approximation, i.e., with allowed large bending angles. We show that the strong-field thin-lens equation is remarkably accurate, even for lightrays that take several turns around the lens before reaching the observer. |
1004.0913 | Yuri Pavlov | A. A. Grib and Yu. V. Pavlov | On the collisions between particles in the vicinity of rotating black
holes | 5 pages, no figure, published version. arXiv admin note: substantial
text overlap with arXiv:1001.0756 | JETP Letters 92 (2010) 125-129 | 10.1134/S0021364010150014 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Scattering of particles in the gravitational field of rotating black holes is
considered. It is shown that scattering energy of particles in the centre of
mass system can obtain very large values not only for extremal black holes but
also for nonextremal ones. Extraction of energy after the collision is
investigated. It is shown that due to the Penrose process the energy of the
particle escaping the hole at infinity can be large. Contradictions in the
problem of getting high energetic particles escaping the black hole are
resolved.
| [
{
"created": "Tue, 6 Apr 2010 17:56:52 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Nov 2014 22:03:17 GMT",
"version": "v2"
}
] | 2014-11-05 | [
[
"Grib",
"A. A.",
""
],
[
"Pavlov",
"Yu. V.",
""
]
] | Scattering of particles in the gravitational field of rotating black holes is considered. It is shown that scattering energy of particles in the centre of mass system can obtain very large values not only for extremal black holes but also for nonextremal ones. Extraction of energy after the collision is investigated. It is shown that due to the Penrose process the energy of the particle escaping the hole at infinity can be large. Contradictions in the problem of getting high energetic particles escaping the black hole are resolved. |
1805.04506 | Avadhut Purohit | Avadhut Purohit | Combined variable field theory in FLRW cosmology | 12 pages, 5 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work aims to study consequences of \textit{combined variable field
theory} developed in [1] by analysing FLRW models of gravity. It shows $\Phi_{q
\rightarrow 0} \rightarrow \infty$ is the Big bang in combined variable field
theoretic settings. Nature of the Universe depends on the new parameter $k$
appearing in the theory. Flat Universe has two disconnected branches namely
expanding and collapsing Universe. Combined variable field for closed Universe
is complex in general. Whereas, the theory of open Universe is necessarily
self-coupled combined variable field theory. But in the large $r$ limit it
reduces to the theory of flat Universe. Resolution of the classical Big bang is
a result of quantisation program. Quantum theory predicts that the size of
Universe was non-zero in the beginning. Combined variable field quantum in
absence of scalar field couplings is interpreted as a quantum of the space. The
energy spectrum of this combined variable field quantum varies with time.
| [
{
"created": "Fri, 11 May 2018 17:51:46 GMT",
"version": "v1"
}
] | 2018-05-14 | [
[
"Purohit",
"Avadhut",
""
]
] | This work aims to study consequences of \textit{combined variable field theory} developed in [1] by analysing FLRW models of gravity. It shows $\Phi_{q \rightarrow 0} \rightarrow \infty$ is the Big bang in combined variable field theoretic settings. Nature of the Universe depends on the new parameter $k$ appearing in the theory. Flat Universe has two disconnected branches namely expanding and collapsing Universe. Combined variable field for closed Universe is complex in general. Whereas, the theory of open Universe is necessarily self-coupled combined variable field theory. But in the large $r$ limit it reduces to the theory of flat Universe. Resolution of the classical Big bang is a result of quantisation program. Quantum theory predicts that the size of Universe was non-zero in the beginning. Combined variable field quantum in absence of scalar field couplings is interpreted as a quantum of the space. The energy spectrum of this combined variable field quantum varies with time. |
2103.03611 | Mohsen Khodadi | Mohsen Khodadi | Black Hole Superradiance in the Presence of Lorentz Symmetry Violation | 18 pages, 4 figures, to appear in PRD | Phys. Rev. D 103, 064051 (2021) | 10.1103/PhysRevD.103.064051 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we consider the massive scalar perturbation on the top of a
small spinning-like black hole in context of Einstein-bumblebee modified
gravity in order to probe the role of spontaneous Lorentz symmetry breaking on
the superradiance scattering and corresponding instability. We show that at the
low-frequency limit of the scalar wave the superradiance scattering will be
enhanced with the Lorentz-violating parameter $\alpha<0$ and will be weakened
with $\alpha>0$. Moreover, by addressing the black hole bomb issue, we extract
an improved bound in the instability regime indicating that $\alpha<0$
increases the parameter space of the scalar field instability, while $\alpha>0$
decreases it.
| [
{
"created": "Fri, 5 Mar 2021 11:29:16 GMT",
"version": "v1"
}
] | 2021-03-24 | [
[
"Khodadi",
"Mohsen",
""
]
] | In this paper we consider the massive scalar perturbation on the top of a small spinning-like black hole in context of Einstein-bumblebee modified gravity in order to probe the role of spontaneous Lorentz symmetry breaking on the superradiance scattering and corresponding instability. We show that at the low-frequency limit of the scalar wave the superradiance scattering will be enhanced with the Lorentz-violating parameter $\alpha<0$ and will be weakened with $\alpha>0$. Moreover, by addressing the black hole bomb issue, we extract an improved bound in the instability regime indicating that $\alpha<0$ increases the parameter space of the scalar field instability, while $\alpha>0$ decreases it. |
2305.08274 | Amodio Carleo | Amodio Carleo, Bilel Ben-Salem | The effect of environment in the timing of a pulsar orbiting SgrA* | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Pulsars are rapidly rotating neutron stars emitting intense electromagnetic
radiation that is detected on Earth as regular and precisely timed pulses. By
exploiting their extreme regularity and comparing the real arrival times with a
theoretical model (pulsar timing), it is possible to deduce many physical
information, not only concerning the neutron star and its possible companion,
but also the properties of the interstellar medium, up to tests of General
Relativity. Last but not least, pulsars are used in conjunction with each other
as a galactic-sized detector for the cosmic background of gravitational waves.
In this paper, we investigate the effect of "matter" on the propagation time
delay of photons emitted by a pulsar orbiting a spinning black hole, one of the
most important relativistic effect in pulsar timing. We deduce an analytical
formula for the time delay from geodesic equations, showing how it changes as
the type of matter around the black hole (radiation, dust or dark energy)
varies with respect to previous results, where matter has not been taken into
account. It turns out that while the spin $a$ only induces a shift in the phase
of the maximum delay without increasing or decreasing the delay, the effect of
matter surrounding the black hole results in a noticeable alteration of it. Our
results show that dark energy would give the strongest effect and that,
interestingly, when the pulsar is positioned between the observer and the black
hole a slightly lower pulse delay than in the no-matter case appears. We
estimated these effects for SGR J1745-2900, the closest magnetar orbiting
SgrA*.
| [
{
"created": "Sun, 14 May 2023 23:12:08 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Nov 2023 18:08:30 GMT",
"version": "v2"
}
] | 2023-11-20 | [
[
"Carleo",
"Amodio",
""
],
[
"Ben-Salem",
"Bilel",
""
]
] | Pulsars are rapidly rotating neutron stars emitting intense electromagnetic radiation that is detected on Earth as regular and precisely timed pulses. By exploiting their extreme regularity and comparing the real arrival times with a theoretical model (pulsar timing), it is possible to deduce many physical information, not only concerning the neutron star and its possible companion, but also the properties of the interstellar medium, up to tests of General Relativity. Last but not least, pulsars are used in conjunction with each other as a galactic-sized detector for the cosmic background of gravitational waves. In this paper, we investigate the effect of "matter" on the propagation time delay of photons emitted by a pulsar orbiting a spinning black hole, one of the most important relativistic effect in pulsar timing. We deduce an analytical formula for the time delay from geodesic equations, showing how it changes as the type of matter around the black hole (radiation, dust or dark energy) varies with respect to previous results, where matter has not been taken into account. It turns out that while the spin $a$ only induces a shift in the phase of the maximum delay without increasing or decreasing the delay, the effect of matter surrounding the black hole results in a noticeable alteration of it. Our results show that dark energy would give the strongest effect and that, interestingly, when the pulsar is positioned between the observer and the black hole a slightly lower pulse delay than in the no-matter case appears. We estimated these effects for SGR J1745-2900, the closest magnetar orbiting SgrA*. |
gr-qc/0401035 | Olaf Dreyer | Olaf Dreyer | New Hints from General Relativity | This essay received an "honorable mention" in the 2003 Essay
Competition of the Gravity Research Foundation | Int.J.Mod.Phys. D12 (2003) 1763 | 10.1142/S0218271803004055 | null | gr-qc | null | The search for a quantum theory of gravity has followed two parallel but
different paths. One aims at arriving at the final theory starting from a
priori assumptions as to its form and building it from the ground up. The other
tries to infer as much as possible about the unknown theory from the existing
ones and use our current knowledge to constrain the possibilities for the
quantum theory of gravity. Probably the biggest success of the second path has
been the results of black hole thermodynamics. The subject of this essay is a
new, highly promising such result, the application of quasinormal modes in
quantum gravity.
| [
{
"created": "Sat, 10 Jan 2004 02:56:29 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Dreyer",
"Olaf",
""
]
] | The search for a quantum theory of gravity has followed two parallel but different paths. One aims at arriving at the final theory starting from a priori assumptions as to its form and building it from the ground up. The other tries to infer as much as possible about the unknown theory from the existing ones and use our current knowledge to constrain the possibilities for the quantum theory of gravity. Probably the biggest success of the second path has been the results of black hole thermodynamics. The subject of this essay is a new, highly promising such result, the application of quasinormal modes in quantum gravity. |
2011.02496 | Merced Montesinos | Merced Montesinos, Diego Gonzalez, Rodrigo Romero, Mariano Celada | Off-shell Noether currents and potentials for first-order general
relativity | Published version | Symmetry 13, 348 (2021) | 10.3390/sym13020348 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We report off-shell Noether currents obtained from off-shell Noether
potentials for first-order general relativity described by $n$-dimensional
Palatini and Holst Lagrangians including the cosmological constant. These
off-shell currents and potentials are achieved by using the corresponding
Lagrangian and the off-shell Noether identities satisfied by diffeomorphisms
generated by arbitrary vector fields, local $SO(n)$ or $SO(n-1,1)$
transformations, `improved diffeomorphisms', and the `generalization of local
translations' of the orthonormal frame and the connection. A remarkable aspect
of our approach is that we do {\it not} use Noether's theorem in its direct
form. By construction, the currents are off-shell conserved and lead naturally
to the definition of off-shell Noether charges. We also study what we call the
`half off-shell' case for both Palatini and Holst Lagrangians. In particular,
we find that the resulting diffeomorphism and local $SO(3,1)$ or $SO(4)$
off-shell Noether currents and potentials for the Holst Lagrangian generically
depend on the Immirzi parameter, which holds even in the `half off-shell' and
on-shell cases. We also study Killing vector fields in the `half off-shell' and
on-shell cases. The current theoretical framework is illustrated for the `half
off-shell' case in static spherically symmetric and
Friedmann--Lemaitre--Robertson--Walker spacetimes in four dimensions.
| [
{
"created": "Wed, 4 Nov 2020 19:00:05 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Mar 2021 14:34:55 GMT",
"version": "v2"
}
] | 2021-03-05 | [
[
"Montesinos",
"Merced",
""
],
[
"Gonzalez",
"Diego",
""
],
[
"Romero",
"Rodrigo",
""
],
[
"Celada",
"Mariano",
""
]
] | We report off-shell Noether currents obtained from off-shell Noether potentials for first-order general relativity described by $n$-dimensional Palatini and Holst Lagrangians including the cosmological constant. These off-shell currents and potentials are achieved by using the corresponding Lagrangian and the off-shell Noether identities satisfied by diffeomorphisms generated by arbitrary vector fields, local $SO(n)$ or $SO(n-1,1)$ transformations, `improved diffeomorphisms', and the `generalization of local translations' of the orthonormal frame and the connection. A remarkable aspect of our approach is that we do {\it not} use Noether's theorem in its direct form. By construction, the currents are off-shell conserved and lead naturally to the definition of off-shell Noether charges. We also study what we call the `half off-shell' case for both Palatini and Holst Lagrangians. In particular, we find that the resulting diffeomorphism and local $SO(3,1)$ or $SO(4)$ off-shell Noether currents and potentials for the Holst Lagrangian generically depend on the Immirzi parameter, which holds even in the `half off-shell' and on-shell cases. We also study Killing vector fields in the `half off-shell' and on-shell cases. The current theoretical framework is illustrated for the `half off-shell' case in static spherically symmetric and Friedmann--Lemaitre--Robertson--Walker spacetimes in four dimensions. |
0909.4217 | Ian Hawke | S. T. Millmore and I. Hawke | Numerical simulations of interfaces in relativistic hydrodynamics | 21 pages, 17 figures | Class.Quant.Grav.27:015007,2010 | 10.1088/0264-9381/27/1/015007 | null | gr-qc physics.comp-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider models of relativistic matter containing sharp interfaces across
which the matter model changes. These models will be relevant for neutron stars
with crusts, phase transitions, or for viscous boundaries where the length
scale is too short to be modelled smoothly. In particular we look at numerical
techniques that allow us to evolve stable interfaces, for the interfaces to
merge, and for strong waves and shocks to interact with the interfaces. We test
these techniques for ideal hydrodynamics in special and general relativity for
simple equations of state, finding that simple level set-based methods extend
well to relativistic hydrodynamics.
| [
{
"created": "Wed, 23 Sep 2009 14:14:31 GMT",
"version": "v1"
}
] | 2010-01-06 | [
[
"Millmore",
"S. T.",
""
],
[
"Hawke",
"I.",
""
]
] | We consider models of relativistic matter containing sharp interfaces across which the matter model changes. These models will be relevant for neutron stars with crusts, phase transitions, or for viscous boundaries where the length scale is too short to be modelled smoothly. In particular we look at numerical techniques that allow us to evolve stable interfaces, for the interfaces to merge, and for strong waves and shocks to interact with the interfaces. We test these techniques for ideal hydrodynamics in special and general relativity for simple equations of state, finding that simple level set-based methods extend well to relativistic hydrodynamics. |
2009.12912 | Jaume Haro | Llibert Areste Salo, Jaume Haro | Quintessential Inflation for Exponential Type Potentials: Scaling and
Tracker Behavior | Version accepted for publication in EPJC | null | 10.1140/epjc/s10052-021-08906-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We will show that for exponential type potentials, which are used to depict
quintessential inflation, the solutions whose initial conditions take place
during the slow roll phase in order to describe correctly the inflationary
period do not belong to the basin of attraction of the scaling solution -a
solution of the scalar field equation whose energy density scale as the one of
the fluid component of the universe during radiation or the matter domination
period-, meaning that a late time mechanism to exit this behavior and depict
correctly the current cosmic acceleration is not needed.
| [
{
"created": "Sun, 27 Sep 2020 18:05:07 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Oct 2020 06:54:18 GMT",
"version": "v2"
},
{
"created": "Thu, 28 Jan 2021 19:32:46 GMT",
"version": "v3"
}
] | 2021-02-24 | [
[
"Salo",
"Llibert Areste",
""
],
[
"Haro",
"Jaume",
""
]
] | We will show that for exponential type potentials, which are used to depict quintessential inflation, the solutions whose initial conditions take place during the slow roll phase in order to describe correctly the inflationary period do not belong to the basin of attraction of the scaling solution -a solution of the scalar field equation whose energy density scale as the one of the fluid component of the universe during radiation or the matter domination period-, meaning that a late time mechanism to exit this behavior and depict correctly the current cosmic acceleration is not needed. |
gr-qc/0612110 | Michael Maziashvili | Michael Maziashvili | Space-time in light of Karolyhazy uncertainty relation | 5 pages, Two misprints are corrected | Int.J.Mod.Phys.D16:1531-1539,2007 | 10.1142/S0218271807010870 | null | gr-qc astro-ph hep-ph hep-th | null | General relativity and quantum mechanics provide a natural explanation for
the existence of dark energy with its observed value and predict its dynamics.
Dark energy proves to be necessary for the existence of space-time itself and
determines the rate of its stability.
| [
{
"created": "Mon, 18 Dec 2006 15:42:57 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Dec 2006 10:41:00 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Maziashvili",
"Michael",
""
]
] | General relativity and quantum mechanics provide a natural explanation for the existence of dark energy with its observed value and predict its dynamics. Dark energy proves to be necessary for the existence of space-time itself and determines the rate of its stability. |
1807.03066 | Pietro Don\`a | Pietro Dona and Giorgio Sarno | Numerical methods for EPRL spin foam transition amplitudes and
Lorentzian recoupling theory | 20 pages, many figures. v2. Typos corrected. v3 minor corrections to
match published version. The library can be downloaded at
http://bitbucket.org/giorgiosarno/sl2cfoam-1.0/ | G. Gen Relativ Gravit (2018) 50: 127 | 10.1007/s10714-018-2452-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The intricated combinatorial structure and the non-compactness of the Lorentz
group have always made the computation of $SL(2,\mathbb{C})$ EPRL spin foam
transition amplitudes a very hard and resource demanding task. With
\texttt{sl2cfoam} we provide a C-coded library for the evaluation of the
Lorentzian EPRL vertex amplitude. We provide a tool to compute the Lorentzian
EPRL 4-simplex vertex amplitude in the intertwiner basis and some utilities to
evaluate SU(2) invariants, booster functions and $SL(2,\mathbb{C})$
Clebsch-Gordan coefficients. We discuss the data storage, parallelizations,
time, and memory performances and possible future developments.
| [
{
"created": "Mon, 9 Jul 2018 12:15:50 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Jul 2018 14:47:29 GMT",
"version": "v2"
},
{
"created": "Tue, 18 Sep 2018 22:45:32 GMT",
"version": "v3"
}
] | 2018-09-20 | [
[
"Dona",
"Pietro",
""
],
[
"Sarno",
"Giorgio",
""
]
] | The intricated combinatorial structure and the non-compactness of the Lorentz group have always made the computation of $SL(2,\mathbb{C})$ EPRL spin foam transition amplitudes a very hard and resource demanding task. With \texttt{sl2cfoam} we provide a C-coded library for the evaluation of the Lorentzian EPRL vertex amplitude. We provide a tool to compute the Lorentzian EPRL 4-simplex vertex amplitude in the intertwiner basis and some utilities to evaluate SU(2) invariants, booster functions and $SL(2,\mathbb{C})$ Clebsch-Gordan coefficients. We discuss the data storage, parallelizations, time, and memory performances and possible future developments. |
2105.06384 | LSC P&P Committee | The LIGO Scientific Collaboration and the Virgo Collaboration: R.
Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, A. Adams, C. Adams,
R. X. Adhikari, V. B. Adya, C. Affeldt, D. Agarwal, M. Agathos, K. Agatsuma,
N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, K. M. Aleman, G.
Allen, A. Allocca, P. A. Altin, A. Amato, S. Anand, A. Ananyeva, S. B.
Anderson, W. G. Anderson, S. V. Angelova, S. Ansoldi, J. M. Antelis, S.
Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Ar\`ene, N. Arnaud,
S. M. Aronson, K. G. Arun, Y. Asali, G. Ashton, S. M. Aston, P. Astone, F.
Aubin, P. Aufmuth, K. AultONeal, C. Austin, S. Babak, F. Badaracco, M. K. M.
Bader, S. Bae, A. M. Baer, S. Bagnasco, Y. Bai, J. Baird, M. Ball, G.
Ballardin, S. W. Ballmer, M. Bals, A. Balsamo, G. Baltus, S. Banagiri, D.
Bankar, R. S. Bankar, J. C. Barayoga, C. Barbieri, B. C. Barish, D. Barker,
P. Barneo, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, D. Barta, J.
Bartlett, M. A. Barton, I. Bartos, R. Bassiri, A. Basti, M. Bawaj, J. C.
Bayley, A. C. Baylor, M. Bazzan, B. B\'ecsy, V. M. Bedakihale, M. Bejger, I.
Belahcene, V. Benedetto, D. Beniwal, M. G. Benjamin, T. F. Bennett, J. D.
Bentley, M. BenYaala, F. Bergamin, B. K. Berger, S. Bernuzzi, C. P. L. Berry,
D. Bersanetti, A. Bertolini, J. Betzwieser, R. Bhandare, A. V. Bhandari, D.
Bhattacharjee, S. Bhaumik, J. Bidler, I. A. Bilenko, G. Billingsley, R.
Birney, O. Birnholtz, S. Biscans, M. Bischi, S. Biscoveanu, A. Bisht, B.
Biswas, M. Bitossi, M.-A. Bizouard, J. K. Blackburn, J. Blackman, C. D.
Blair, D. G. Blair, R. M. Blair, F. Bobba, N. Bode, M. Boer, G. Bogaert, M.
Boldrini, F. Bondu, E. Bonilla, R. Bonnand, P. Booker, B. A. Boom, R. Bork,
V. Boschi, N. Bose, S. Bose, V. Bossilkov, V. Boudart, Y. Bouffanais, A.
Bozzi, C. Bradaschia, P. R. Brady, A. Bramley, A. Branch, M. Branchesi, J. E.
Brau, M. Breschi, T. Briant, J. H. Briggs, A. Brillet, M. Brinkmann, P.
Brockill, A. F. Brooks, J. Brooks, D. D. Brown, S. Brunett, G. Bruno, R.
Bruntz, J. Bryant, A. Buikema, T. Bulik, H. J. Bulten, A. Buonanno, R.
Buscicchio, D. Buskulic, R. L. Byer, L. Cadonati, M. Caesar, G. Cagnoli, C.
Cahillane, H. W. Cain III, J. Calder\'on Bustillo, J. D. Callaghan, T. A.
Callister, E. Calloni, J. B. Camp, M. Canepa, M. Cannavacciuolo, K. C.
Cannon, H. Cao, J. Cao, E. Capote, G. Carapella, F. Carbognani, J. B. Carlin,
M. F. Carney, M. Carpinelli, G. Carullo, T. L. Carver, J. Casanueva Diaz, C.
Casentini, G. Castaldi, S. Caudill, M. Cavagli\`a, F. Cavalier, R. Cavalieri,
G. Cella, P. Cerd\'a-Dur\'an, E. Cesarini, W. Chaibi, K. Chakravarti, B.
Champion, C.-H. Chan, C. Chan, C. L. Chan, K. Chandra, P. Chanial, S. Chao,
P. Charlton, E. A. Chase, E. Chassande-Mottin, D. Chatterjee, M. Chaturvedi,
A. Chen, H. Y. Chen, J. Chen, X. Chen, Y. Chen, Z. Chen, H. Cheng, C. K.
Cheong, H. Y. Cheung, H. Y. Chia, F. Chiadini, R. Chierici, A. Chincarini, M.
L. Chiofalo, A. Chiummo, G. Cho, H. S. Cho, S. Choate, R. K. Choudhary, S.
Choudhary, N. Christensen, Q. Chu, S. Chua, K. W. Chung, G. Ciani, P.
Ciecielag, M. Cie\'slar, M. Cifaldi, A. A. Ciobanu, R. Ciolfi, F. Cipriano,
A. Cirone, F. Clara, E. N. Clark, J. A. Clark, L. Clarke, P. Clearwater, S.
Clesse, F. Cleva, E. Coccia, P.-F. Cohadon, D. E. Cohen, L. Cohen, M.
Colleoni, C. G. Collette, M. Colpi, C. M. Compton, M. Constancio Jr., L.
Conti, S. J. Cooper, P. Corban, T. R. Corbitt, I. Cordero-Carri\'on, S.
Corezzi, K. R. Corley, N. Cornish, D. Corre, A. Corsi, S. Cortese, C. A.
Costa, R. Cotesta, M. W. Coughlin, S. B. Coughlin, J.-P. Coulon, S. T.
Countryman, B. Cousins, P. Couvares, P. B. Covas, D. M. Coward, M. J. Cowart,
D. C. Coyne, R. Coyne, J. D. E. Creighton, T. D. Creighton, A. W. Criswell,
M. Croquette, S. G. Crowder, J. R. Cudell, T. J. Cullen, A. Cumming, R.
Cummings, E. Cuoco, M. Cury{\l}o, T. Dal Canton, G. D\'alya, A. Dana, L. M.
DaneshgaranBajastani, B. D'Angelo, S. L. Danilishin, S. D'Antonio, K.
Danzmann, C. Darsow-Fromm, A. Dasgupta, L. E. H. Datrier, V. Dattilo, I.
Dave, M. Davier, G. S. Davies, D. Davis, E. J. Daw, R. Dean, D. DeBra, M.
Deenadayalan, J. Degallaix, M. De Laurentis, S. Del\'eglise, V. Del Favero,
F. De Lillo, N. De Lillo, W. Del Pozzo, L. M. DeMarchi, F. De Matteis, V.
D'Emilio, N. Demos, T. Dent, A. Depasse, R. De Pietri, R. De Rosa, C. De
Rossi, R. DeSalvo, R. De Simone, S. Dhurandhar, M. C. D\'iaz, M. Diaz-Ortiz
Jr., N. A. Didio, T. Dietrich, L. Di Fiore, C. Di Fronzo, C. Di Giorgio, F.
Di Giovanni, T. Di Girolamo, A. Di Lieto, B. Ding, S. Di Pace, I. Di Palma,
F. Di Renzo, A. K. Divakarla, A. Dmitriev, Z. Doctor, L. D'Onofrio, F.
Donovan, K. L. Dooley, S. Doravari, I. Dorrington, M. Drago, J. C. Driggers,
Y. Drori, Z. Du, J.-G. Ducoin, P. Dupej, O. Durante, D. D'Urso, P.-A.
Duverne, S. E. Dwyer, P. J. Easter, M. Ebersold, G. Eddolls, B. Edelman, T.
B. Edo, O. Edy, A. Effler, J. Eichholz, S. S. Eikenberry, M. Eisenmann, R. A.
Eisenstein, A. Ejlli, L. Errico, R. C. Essick, H. Estell\'es, D. Estevez, Z.
Etienne, T. Etzel, M. Evans, T. M. Evans, B. E. Ewing, J. M. Ezquiaga, V.
Fafone, H. Fair, S. Fairhurst, X. Fan, A. M. Farah, S. Farinon, B. Farr, W.
M. Farr, N. W. Farrow, E. J. Fauchon-Jones, M. Favata, M. Fays, M. Fazio, J.
Feicht, M. M. Fejer, F. Feng, E. Fenyvesi, D. L. Ferguson, A.
Fernandez-Galiana, I. Ferrante, T. A. Ferreira, F. Fidecaro, P. Figura, I.
Fiori, M. Fishbach, R. P. Fisher, R. Fittipaldi, V. Fiumara, R. Flaminio, E.
Floden, E. Flynn, H. Fong, J. A. Font, B. Fornal, P. W. F. Forsyth, A.
Franke, S. Frasca, F. Frasconi, C. Frederick, Z. Frei, A. Freise, R. Frey, P.
Fritschel, V. V. Frolov, G. G. Fronz\'e, P. Fulda, M. Fyffe, H. A. Gabbard,
B. U. Gadre, S. M. Gaebel, J. R. Gair, J. Gais, S. Galaudage, R. Gamba, D.
Ganapathy, A. Ganguly, S. G. Gaonkar, B. Garaventa, C. Garc\'ia-N\'u\~nez, C.
Garc\'ia-Quir\'os, F. Garufi, B. Gateley, S. Gaudio, V. Gayathri, G. Gemme,
A. Gennai, J. George, L. Gergely, P. Gewecke, S. Ghonge, Abhirup. Ghosh,
Archisman Ghosh, Shaon Ghosh, Shrobana Ghosh, Sourath Ghosh, B. Giacomazzo,
L. Giacoppo, J. A. Giaime, K. D. Giardina, D. R. Gibson, C. Gier, M. Giesler,
P. Giri, F. Gissi, J. Glanzer, A. E. Gleckl, P. Godwin, E. Goetz, R. Goetz,
N. Gohlke, B. Goncharov, G. Gonz\'alez, A. Gopakumar, M. Gosselin, R. Gouaty,
S. Goyal, B. Grace, A. Grado, M. Granata, V. Granata, A. Grant, S. Gras, P.
Grassia, C. Gray, R. Gray, G. Greco, A. C. Green, R. Green, A. M. Gretarsson,
E. M. Gretarsson, D. Griffith, W. Griffiths, H. L. Griggs, G. Grignani, A.
Grimaldi, E. Grimes, S. J. Grimm, H. Grote, S. Grunewald, P. Gruning, J. G.
Guerrero, G. M. Guidi, A. R. Guimaraes, G. Guix\'e, H. K. Gulati, H.-K. Guo,
Y. Guo, Anchal Gupta, Anuradha Gupta, P. Gupta, E. K. Gustafson, R.
Gustafson, F. Guzman, L. Haegel, O. Halim, E. D. Hall, E. Z. Hamilton, G.
Hammond, M. Haney, J. Hanks, C. Hanna, M. D. Hannam, O. A. Hannuksela, H.
Hansen, T. J. Hansen, J. Hanson, T. Harder, T. Hardwick, K. Haris, J. Harms,
G. M. Harry, I. W. Harry, D. Hartwig, B. Haskell, R. K. Hasskew, C.-J.
Haster, K. Haughian, F. J. Hayes, J. Healy, A. Heidmann, M. C. Heintze, J.
Heinze, J. Heinzel, H. Heitmann, F. Hellman, P. Hello, A. F.
Helmling-Cornell, G. Hemming, M. Hendry, I. S. Heng, E. Hennes, J. Hennig, M.
H. Hennig, F. Hernandez Vivanco, M. Heurs, S. Hild, P. Hill, A. S. Hines, S.
Hochheim, D. Hofman, J. N. Hohmann, A. M. Holgado, N. A. Holland, I. J.
Hollows, Z. J. Holmes, K. Holt, D. E. Holz, P. Hopkins, J. Hough, E. J.
Howell, C. G. Hoy, D. Hoyland, A. Hreibi, Y. Hsu, Y. Huang, M. T. H\"ubner,
A. D. Huddart, E. A. Huerta, B. Hughey, V. Hui, S. Husa, S. H. Huttner, R.
Huxford, T. Huynh-Dinh, B. Idzkowski, A. Iess, H. Inchauspe, C. Ingram, G.
Intini, M. Isi, K. Isleif, B. R. Iyer, V. JaberianHamedan, T. Jacqmin, S. J.
Jadhav, S. P. Jadhav, A. L. James, A. Z. Jan, K. Jani, J. Janquart, K.
Janssens, N. N. Janthalur, P. Jaranowski, D. Jariwala, R. Jaume, A. C.
Jenkins, M. Jeunon, W. Jia, J. Jiang, G. R. Johns, A. W. Jones, D. I. Jones,
J. D. Jones, P. Jones, R. Jones, R. J. G. Jonker, L. Ju, J. Junker, C. V.
Kalaghatgi, V. Kalogera, B. Kamai, S. Kandhasamy, G. Kang, J. B. Kanner, Y.
Kao, S. J. Kapadia, D. P. Kapasi, S. Karat, C. Karathanasis, S. Karki, R.
Kashyap, M. Kasprzack, W. Kastaun, S. Katsanevas, E. Katsavounidis, W.
Katzman, T. Kaur, K. Kawabe, F. K\'ef\'elian, D. Keitel, J. S. Key, S.
Khadka, F. Y. Khalili, I. Khan, S. Khan, E. A. Khazanov, N. Khetan, M.
Khursheed, N. Kijbunchoo, C. Kim, J. C. Kim, K. Kim, W. S. Kim, Y.-M. Kim, C.
Kimball, P. J. King, M. Kinley-Hanlon, R. Kirchhoff, J. S. Kissel, L.
Kleybolte, S. Klimenko, A. M. Knee, T. D. Knowles, E. Knyazev, P. Koch, G.
Koekoek, S. Koley, P. Kolitsidou, M. Kolstein, K. Komori, V. Kondrashov, A.
Kontos, N. Koper, M. Korobko, M. Kovalam, D. B. Kozak, V. Kringel, N. V.
Krishnendu, A. Kr\'olak, G. Kuehn, F. Kuei, A. Kumar, P. Kumar, Rahul Kumar,
Rakesh Kumar, K. Kuns, S. Kwang, D. Laghi, E. Lalande, T. L. Lam, A.
Lamberts, M. Landry, B. B. Lane, R. N. Lang, J. Lange, B. Lantz, I. La Rosa,
A. Lartaux-Vollard, P. D. Lasky, M. Laxen, A. Lazzarini, C. Lazzaro, P.
Leaci, S. Leavey, Y. K. Lecoeuche, H. M. Lee, H. W. Lee, J. Lee, K. Lee, J.
Lehmann, A. Lema\^itre, E. Leon, N. Leroy, N. Letendre, Y. Levin, J. N.
Leviton, A. K. Y. Li, B. Li, J. Li, T. G. F. Li, X. Li, F. Linde, S. D.
Linker, J. N. Linley, T. B. Littenberg, J. Liu, K. Liu, X. Liu, M.
Llorens-Monteagudo, R. K. L. Lo, A. Lockwood, M. L. Lollie, L. T. London, A.
Longo, D. Lopez, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. D.
Lough, C. O. Lousto, G. Lovelace, H. L\"uck, D. Lumaca, A. P. Lundgren, R.
Macas, M. MacInnis, D. M. Macleod, I. A. O. MacMillan, A. Macquet, I.
Maga\~na Hernandez, F. Maga\~na-Sandoval, C. Magazz\`u, R. M. Magee, R.
Maggiore, E. Majorana, C. Makarem, I. Maksimovic, S. Maliakal, A. Malik, N.
Man, V. Mandic, V. Mangano, J. L. Mango, G. L. Mansell, M. Manske, M.
Mantovani, M. Mapelli, F. Marchesoni, F. Marion, Z. Mark, S. M\'arka, Z.
M\'arka, C. Markakis, A. S. Markosyan, A. Markowitz, E. Maros, A. Marquina,
S. Marsat, F. Martelli, I. W. Martin, R. M. Martin, M. Martinez, V. Martinez,
K. Martinovic, D. V. Martynov, E. J. Marx, H. Masalehdan, K. Mason, E.
Massera, A. Masserot, T. J. Massinger, M. Masso-Reid, S. Mastrogiovanni, A.
Matas, M. Mateu-Lucena, F. Matichard, M. Matiushechkina, N. Mavalvala, J. J.
McCann, R. McCarthy, D. E. McClelland, P. McClincy, S. McCormick, L.
McCuller, G. I. McGhee, S. C. McGuire, C. McIsaac, J. McIver, D. J. McManus,
T. McRae, S. T. McWilliams, D. Meacher, M. Mehmet, A. K. Mehta, A. Melatos,
D. A. Melchor, G. Mendell, A. Menendez-Vazquez, C. S. Menoni, R. A. Mercer,
L. Mereni, K. Merfeld, E. L. Merilh, J. D. Merritt, M. Merzougui, S. Meshkov,
C. Messenger, C. Messick, P. M. Meyers, F. Meylahn, A. Mhaske, A. Miani, H.
Miao, I. Michaloliakos, C. Michel, H. Middleton, L. Milano, A. L. Miller, M.
Millhouse, J. C. Mills, E. Milotti, M. C. Milovich-Goff, O. Minazzoli, Y.
Minenkov, Ll. M. Mir, A. Mishkin, C. Mishra, T. Mishra, T. Mistry, S. Mitra,
V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, Geoffrey Mo, K. Mogushi, S.
R. P. Mohapatra, S. R. Mohite, I. Molina, M. Molina-Ruiz, M. Mondin, M.
Montani, C. J. Moore, D. Moraru, F. Morawski, A. More, S. More, C. Moreno, G.
Moreno, S. Morisaki, B. Mours, C. M. Mow-Lowry, S. Mozzon, F. Muciaccia,
Arunava Mukherjee, D. Mukherjee, Soma Mukherjee, Subroto Mukherjee, N.
Mukund, A. Mullavey, J. Munch, E. A. Mu\~niz, P. G. Murray, R. Musenich, S.
L. Nadji, A. Nagar, I. Nardecchia, L. Naticchioni, B. Nayak, R. K. Nayak, B.
F. Neil, J. Neilson, G. Nelemans, T. J. N. Nelson, M. Nery, A. Neunzert, K.
Y. Ng, S. W. S. Ng, C. Nguyen, P. Nguyen, T. Nguyen, S. A. Nichols, S.
Nissanke, F. Nocera, M. Noh, M. Norman, C. North, L. K. Nuttall, J. Oberling,
B. D. O'Brien, J. O'Dell, G. Oganesyan, J. J. Oh, S. H. Oh, F. Ohme, H. Ohta,
M. A. Okada, C. Olivetto, R. Oram, B. O'Reilly, R. G. Ormiston, N. D. Ormsby,
L. F. Ortega, R. O'Shaughnessy, E. O'Shea, S. Ossokine, C. Osthelder, D. J.
Ottaway, H. Overmier, A. E. Pace, G. Pagano, M. A. Page, G. Pagliaroli, A.
Pai, S. A. Pai, J. R. Palamos, O. Palashov, C. Palomba, P. K. Panda, P. T. H.
Pang, C. Pankow, F. Pannarale, B. C. Pant, F. Paoletti, A. Paoli, A. Paolone,
W. Parker, D. Pascucci, A. Pasqualetti, R. Passaquieti, D. Passuello, M.
Patel, B. Patricelli, E. Payne, T. C. Pechsiri, M. Pedraza, M. Pegoraro, A.
Pele, S. Penn, A. Perego, A. Pereira, T. Pereira, C. J. Perez, C. P\'erigois,
A. Perreca, S. Perri\`es, J. Petermann, D. Petterson, H. P. Pfeiffer, K. A.
Pham, K. S. Phukon, O. J. Piccinni, M. Pichot, M. Piendibene, F.
Piergiovanni, L. Pierini, V. Pierro, G. Pillant, F. Pilo, L. Pinard, I. M.
Pinto, B. J. Piotrzkowski, K. Piotrzkowski, M. Pirello, M. Pitkin, E.
Placidi, W. Plastino, C. Pluchar, R. Poggiani, E. Polini, D. Y. T. Pong, S.
Ponrathnam, P. Popolizio, E. K. Porter, J. Powell, M. Pracchia, T. Pradier,
A. K. Prajapati, K. Prasai, R. Prasanna, G. Pratten, T. Prestegard, M.
Principe, G. A. Prodi, L. Prokhorov, P. Prosposito, L. Prudenzi, A. Puecher,
M. Punturo, F. Puosi, P. Puppo, M. P\"urrer, H. Qi, V. Quetschke, P. J.
Quinonez, R. Quitzow-James, F. J. Raab, G. Raaijmakers, H. Radkins, N.
Radulesco, P. Raffai, S. X. Rail, S. Raja, C. Rajan, K. E. Ramirez, T. D.
Ramirez, A. Ramos-Buades, J. Rana, P. Rapagnani, U. D. Rapol, B. Ratto, V.
Raymond, N. Raza, M. Razzano, J. Read, L. A. Rees, T. Regimbau, L. Rei, S.
Reid, D. H. Reitze, P. Relton, P. Rettegno, F. Ricci, C. J. Richardson, J. W.
Richardson, L. Richardson, P. M. Ricker, G. Riemenschneider, K. Riles, M.
Rizzo, N. A. Robertson, R. Robie, F. Robinet, A. Rocchi, J. A. Rocha, S.
Rodriguez, R. D. Rodriguez-Soto, L. Rolland, J. G. Rollins, V. J. Roma, M.
Romanelli, R. Romano, C. L. Romel, A. Romero, I. M. Romero-Shaw, J. H. Romie,
C. A. Rose, D. Rosi\'nska, S. G. Rosofsky, M. P. Ross, S. Rowan, S. J.
Rowlinson, Santosh Roy, Soumen Roy, D. Rozza, P. Ruggi, K. Ryan, S. Sachdev,
T. Sadecki, J. Sadiq, M. Sakellariadou, O. S. Salafia, L. Salconi, M. Saleem,
F. Salemi, A. Samajdar, E. J. Sanchez, J. H. Sanchez, L. E. Sanchez, N.
Sanchis-Gual, J. R. Sanders, A. Sanuy, T. R. Saravanan, N. Sarin, B.
Sassolas, H. Satari, B. S. Sathyaprakash, O. Sauter, R. L. Savage, V. Savant,
D. Sawant, H. L. Sawant, S. Sayah, D. Schaetzl, M. Scheel, J. Scheuer, A.
Schindler-Tyka, P. Schmidt, R. Schnabel, M. Schneewind, R. M. S. Schofield,
A. Sch\"onbeck, B. W. Schulte, B. F. Schutz, E. Schwartz, J. Scott, S. M.
Scott, M. Seglar-Arroyo, E. Seidel, D. Sellers, A. S. Sengupta, N. Sennett,
D. Sentenac, E. G. Seo, V. Sequino, A. Sergeev, Y. Setyawati, T. Shaffer, M.
S. Shahriar, B. Shams, S. Sharifi, A. Sharma, P. Sharma, P. Shawhan, N. S.
Shcheblanov, H. Shen, M. Shikauchi, R. Shink, D. H. Shoemaker, D. M.
Shoemaker, K. Shukla, S. ShyamSundar, M. Sieniawska, D. Sigg, L. P. Singer,
D. Singh, N. Singh, A. Singha, A. M. Sintes, V. Sipala, V. Skliris, B. J. J.
Slagmolen, T. J. Slaven-Blair, J. Smetana, J. R. Smith, R. J. E. Smith, S. N.
Somala, E. J. Son, K. Soni, S. Soni, B. Sorazu, V. Sordini, F. Sorrentino, N.
Sorrentino, R. Soulard, T. Souradeep, E. Sowell, V. Spagnuolo, A. P. Spencer,
M. Spera, A. K. Srivastava, V. Srivastava, K. Staats, C. Stachie, D. A.
Steer, J. Steinlechner, S. Steinlechner, D. J. Stops, M. Stover, K. A.
Strain, L. C. Strang, G. Stratta, A. Strunk, R. Sturani, A. L. Stuver, J.
S\"udbeck, S. Sudhagar, V. Sudhir, H. G. Suh, T. Z. Summerscales, H. Sun, L.
Sun, S. Sunil, A. Sur, J. Suresh, P. J. Sutton, B. L. Swinkels, M. J.
Szczepa\'nczyk, P. Szewczyk, M. Tacca, S. C. Tait, C. Talbot, A. J.
Tanasijczuk, D. B. Tanner, D. Tao, A. Tapia, E. N. Tapia San Martin, J. D.
Tasson, R. Tenorio, L. Terkowski, M. Test, M. P. Thirugnanasambandam, M.
Thomas, P. Thomas, J. E. Thompson, S. R. Thondapu, K. A. Thorne, E. Thrane,
Shubhanshu Tiwari, Srishti Tiwari, V. Tiwari, K. Toland, A. E. Tolley, M.
Tonelli, A. Torres-Forn\'e, C. I. Torrie, I. Tosta e Melo, D. T\"oyr\"a, A.
Trapananti, F. Travasso, G. Traylor, M. C. Tringali, A. Tripathee, L.
Troiano, A. Trovato, R. J. Trudeau, D. S. Tsai, D. Tsai, K. W. Tsang, M. Tse,
R. Tso, L. Tsukada, D. Tsuna, T. Tsutsui, M. Turconi, A. S. Ubhi, R. P.
Udall, K. Ueno, D. Ugolini, C. S. Unnikrishnan, A. L. Urban, S. A. Usman, A.
C. Utina, H. Vahlbruch, G. Vajente, A. Vajpeyi, G. Valdes, M. Valentini, V.
Valsan, N. van Bakel, M. van Beuzekom, J. F. J. van den Brand, C. Van Den
Broeck, D. C. Vander-Hyde, L. van der Schaaf, J. V. van Heijningen, J.
Vanosky, M. Vardaro, A. F. Vargas, V. Varma, M. Vas\'uth, A. Vecchio, G.
Vedovato, J. Veitch, P. J. Veitch, K. Venkateswara, J. Venneberg, G.
Venugopalan, D. Verkindt, Y. Verma, D. Veske, F. Vetrano, A. Vicer\'e, A. D.
Viets, V. Villa-Ortega, J.-Y. Vinet, S. Vitale, T. Vo, H. Vocca, E. R. G. von
Reis, J. von Wrangel, C. Vorvick, S. P. Vyatchanin, L. E. Wade, M. Wade, K.
J. Wagner, R. C. Walet, M. Walker, G. S. Wallace, L. Wallace, S. Walsh, J. Z.
Wang, W. H. Wang, R. L. Ward, J. Warner, M. Was, N. Y. Washington, J. Watchi,
B. Weaver, L. Wei, M. Weinert, A. J. Weinstein, R. Weiss, C. M. Weller, F.
Wellmann, L. Wen, P. We{\ss}els, J. W. Westhouse, K. Wette, J. T. Whelan, D.
D. White, B. F. Whiting, C. Whittle, D. Wilken, D. Williams, M. J. Williams,
A. R. Williamson, J. L. Willis, B. Willke, D. J. Wilson, W. Winkler, C. C.
Wipf, T. Wlodarczyk, G. Woan, J. Woehler, J. K. Wofford, I. C. F. Wong, M.
Wright, D. S. Wu, D. M. Wysocki, L. Xiao, H. Yamamoto, F. W. Yang, L. Yang,
Y. Yang, Z. Yang, M. J. Yap, D. W. Yeeles, A. B. Yelikar, M. C. Yeung, M.
Ying, A. Yoon, Hang Yu, Haocun Yu, A. Zadro\.zny, M. Zanolin, T. Zelenova,
J.-P. Zendri, M. Zevin, J. Zhang, L. Zhang, R. Zhang, T. Zhang, C. Zhao, G.
Zhao, Y. Zhao, Z. Zhou, X. J. Zhu, A. B. Zimmerman, M. E. Zucker, J. Zweizig | Search for lensing signatures in the gravitational-wave observations
from the first half of LIGO-Virgo's third observing run | 31 pages and 6 figures. Accepted by the Astrophysical Journal | null | 10.3847/1538-4357/ac23db | LIGO-P2000400 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We search for signatures of gravitational lensing in the gravitational-wave
signals from compact binary coalescences detected by Advanced LIGO and Advanced
Virgo during O3a, the first half of their third observing run. We study: 1) the
expected rate of lensing at current detector sensitivity and the implications
of a non-observation of strong lensing or a stochastic gravitational-wave
background on the merger-rate density at high redshift; 2) how the
interpretation of individual high-mass events would change if they were found
to be lensed; 3) the possibility of multiple images due to strong lensing by
galaxies or galaxy clusters; and 4) possible wave-optics effects due to
point-mass microlenses. Several pairs of signals in the multiple-image analysis
show similar parameters and, in this sense, are nominally consistent with the
strong lensing hypothesis. However, taking into account population priors,
selection effects, and the prior odds against lensing, these events do not
provide sufficient evidence for lensing. Overall, we find no compelling
evidence for lensing in the observed gravitational-wave signals from any of
these analyses.
| [
{
"created": "Thu, 13 May 2021 16:12:18 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Jun 2021 13:31:38 GMT",
"version": "v2"
},
{
"created": "Tue, 30 Nov 2021 17:55:25 GMT",
"version": "v3"
}
] | 2022-04-13 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"Abbott",
"R.",
""
],
[
"Abbott",
"T. D.",
""
],
[
"Abraham",
"S.",
""
],
[
"Acernese",
"F.",
""
],
[
"Ackley",
"K.",
... | We search for signatures of gravitational lensing in the gravitational-wave signals from compact binary coalescences detected by Advanced LIGO and Advanced Virgo during O3a, the first half of their third observing run. We study: 1) the expected rate of lensing at current detector sensitivity and the implications of a non-observation of strong lensing or a stochastic gravitational-wave background on the merger-rate density at high redshift; 2) how the interpretation of individual high-mass events would change if they were found to be lensed; 3) the possibility of multiple images due to strong lensing by galaxies or galaxy clusters; and 4) possible wave-optics effects due to point-mass microlenses. Several pairs of signals in the multiple-image analysis show similar parameters and, in this sense, are nominally consistent with the strong lensing hypothesis. However, taking into account population priors, selection effects, and the prior odds against lensing, these events do not provide sufficient evidence for lensing. Overall, we find no compelling evidence for lensing in the observed gravitational-wave signals from any of these analyses. |
1603.02676 | Alexei Zayats | Alexander B. Balakin, Jos\'e P. S. Lemos, Alexei E. Zayats | Magnetic black holes and monopoles in a nonminimal Einstein-Yang-Mills
theory with a cosmological constant: Exact solutions | 20 pages, 6 figures | Phys. Rev. D 93, 084004 (2016) | 10.1103/PhysRevD.93.084004 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Alternative theories of gravity and their solutions are of considerable
importance since at some fundamental level the world can reveal new features.
Indeed, it is suspected that the gravitational field might be nonminimally
coupled to the other fields at scales not yet probed, bringing into the
forefront nonminimally coupled theories. In this mode, we consider a nonminimal
Einstein-Yang-Mills theory with a cosmological constant. Imposing spherical
symmetry and staticity for the spacetime and a magnetic Wu-Yang ansatz for the
Yang-Mills field, we find expressions for the solutions of the theory. Further
imposing constraints on the nonminimal parameters, we find a family of exact
solutions of the theory depending on five parameters, namely, two nonminimal
parameters, the cosmological constant, the magnetic charge, and the mass. These
solutions represent magnetic monopoles and black holes in magnetic monopoles
with de Sitter, Minkowskian, and anti-de Sitter asymptotics, depending on the
sign and value of the cosmological constant $\Lambda$. We classify completely
the family of solutions with respect to the number and the type of horizons and
show that the spacetime solutions can have, at most, four horizons. For
particular sets of the parameters, these horizons can become double, triple,
and quadruple. For instance, for a positive cosmological constant $\Lambda$,
there is a critical $\Lambda_c$ for which the solution admits a quadruple
horizon, evocative of the $\Lambda_c$ that appears for a given energy density
in both the Einstein static and Eddington-Lema\^{\i}tre dynamical universes. As
an example of our classification, we analyze solutions in the Drummond-Hathrell
nonminimal theory that describe nonminimal black holes. Another application is
with a set of regular black holes previously treated.
| [
{
"created": "Tue, 8 Mar 2016 20:59:47 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Apr 2016 20:41:18 GMT",
"version": "v2"
}
] | 2016-04-06 | [
[
"Balakin",
"Alexander B.",
""
],
[
"Lemos",
"José P. S.",
""
],
[
"Zayats",
"Alexei E.",
""
]
] | Alternative theories of gravity and their solutions are of considerable importance since at some fundamental level the world can reveal new features. Indeed, it is suspected that the gravitational field might be nonminimally coupled to the other fields at scales not yet probed, bringing into the forefront nonminimally coupled theories. In this mode, we consider a nonminimal Einstein-Yang-Mills theory with a cosmological constant. Imposing spherical symmetry and staticity for the spacetime and a magnetic Wu-Yang ansatz for the Yang-Mills field, we find expressions for the solutions of the theory. Further imposing constraints on the nonminimal parameters, we find a family of exact solutions of the theory depending on five parameters, namely, two nonminimal parameters, the cosmological constant, the magnetic charge, and the mass. These solutions represent magnetic monopoles and black holes in magnetic monopoles with de Sitter, Minkowskian, and anti-de Sitter asymptotics, depending on the sign and value of the cosmological constant $\Lambda$. We classify completely the family of solutions with respect to the number and the type of horizons and show that the spacetime solutions can have, at most, four horizons. For particular sets of the parameters, these horizons can become double, triple, and quadruple. For instance, for a positive cosmological constant $\Lambda$, there is a critical $\Lambda_c$ for which the solution admits a quadruple horizon, evocative of the $\Lambda_c$ that appears for a given energy density in both the Einstein static and Eddington-Lema\^{\i}tre dynamical universes. As an example of our classification, we analyze solutions in the Drummond-Hathrell nonminimal theory that describe nonminimal black holes. Another application is with a set of regular black holes previously treated. |
2405.08670 | Michele Arzano | Francesco Alessio and Michele Arzano | Infrared gravity and a celestial obstruction to monogamy constraints | 7 pages, no figures. Slightly edited version of the essay selected
for a Honorable Mention in the 2024 Gravity Research Foundation Competition | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We argue that gravitational interactions between particles require a
departure from the conventional picture of the quantum state of a multiparticle
system in terms of tensor products of one-particle states. This modification is
essential in order to accommodate the existence of a new boost-like
relativistic angular momentum charge which pairs of particles must carry
asymptotically due to long-range effects of gravity. These findings challenge
conventional assumptions, prompting a reevaluation of the constraints on
quantum entanglement between particle subsystems in a black hole geometry.
| [
{
"created": "Tue, 14 May 2024 14:52:39 GMT",
"version": "v1"
}
] | 2024-05-15 | [
[
"Alessio",
"Francesco",
""
],
[
"Arzano",
"Michele",
""
]
] | We argue that gravitational interactions between particles require a departure from the conventional picture of the quantum state of a multiparticle system in terms of tensor products of one-particle states. This modification is essential in order to accommodate the existence of a new boost-like relativistic angular momentum charge which pairs of particles must carry asymptotically due to long-range effects of gravity. These findings challenge conventional assumptions, prompting a reevaluation of the constraints on quantum entanglement between particle subsystems in a black hole geometry. |
gr-qc/0012026 | Daniel Grumiller | D.Grumiller, D.Hofmann, W.Kummer | 2D gravity without test particles is pointless (Comment on
hep-th/0011136) | 5 pages, LaTex 3.14159, uses amsmath and amssymb | Mod.Phys.Lett. A16 (2001) 1597-1600 | 10.1142/S0217732301004935 | TUW--00--32 | gr-qc hep-th | null | Claims of a general Weyl invariance of an arbitrary 2D dilaton theory are
critically discussed.
| [
{
"created": "Wed, 6 Dec 2000 15:09:53 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Grumiller",
"D.",
""
],
[
"Hofmann",
"D.",
""
],
[
"Kummer",
"W.",
""
]
] | Claims of a general Weyl invariance of an arbitrary 2D dilaton theory are critically discussed. |
2205.15267 | Gabriel S\'anchez-P\'erez | Marc Mars and Gabriel S\'anchez-P\'erez | Double Null Data and the Characteristic Problem in General Relativity | The presentation of the proof of Theorem 7.15 has been improved.
Several typos has been amended. Some long computations has been moved to
appendices | Journal of Physics A: Mathematical and Theoretical, 2023 | 10.1088/1751-8121/acb098 | null | gr-qc math.AP math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | General hypersurfaces of any causal character can be studied abstractly using
the hypersurface data formalism. In the null case, we write down all tangential
components of the ambient Ricci tensor in terms of the abstract data. Using
this formalism, we formulate and solve in a completely abstract way the
characteristic Cauchy problem of the Einstein vacuum field equations. The
initial data is detached from any spacetime notion, and it is fully
diffeomorphism and gauge covariant. The results of this paper put the
characteristic problem on a similar footing as the standard Cauchy problem in
General Relativity.
| [
{
"created": "Mon, 30 May 2022 17:20:11 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Jan 2023 13:31:05 GMT",
"version": "v2"
}
] | 2023-01-09 | [
[
"Mars",
"Marc",
""
],
[
"Sánchez-Pérez",
"Gabriel",
""
]
] | General hypersurfaces of any causal character can be studied abstractly using the hypersurface data formalism. In the null case, we write down all tangential components of the ambient Ricci tensor in terms of the abstract data. Using this formalism, we formulate and solve in a completely abstract way the characteristic Cauchy problem of the Einstein vacuum field equations. The initial data is detached from any spacetime notion, and it is fully diffeomorphism and gauge covariant. The results of this paper put the characteristic problem on a similar footing as the standard Cauchy problem in General Relativity. |
gr-qc/9911049 | Marcelo J. Reboucas | G.I. Gomero, M.J. Reboucas, A.F.F. Teixeira | A Topological Signature in Cosmic Topology | 27 pages, 7 figures, LaTeX2e. Inserted: clarifying details, a
connection with CCP method, new references. To appear in Class. Quantum Grav.
(2001) in the present form | Class.Quant.Grav. 18 (2001) 1885-1906 | 10.1088/0264-9381/18/10/306 | CBPF-NF-056/99 | gr-qc astro-ph hep-th | null | Two procedures for obtaining (extracting and constructing) the topological
signature of any multiply connected Robertson-Walker (RW) universe are
presented. It is shown through computer-aided simulations that both approaches
give rise to the same topological signature for a multiply connected flat RW
universe. The strength of these approaches is illustrated by extracting the
topological signatures of a flat ($k=0$), an elliptic ($k=1$), and a hyperbolic
($k=-1$) multiply connected RW universes. We also show how separated
contributions of the covering isometries add up to form the topological
signature of a RW flat universe. There emerges from our theoretical results and
simulations that the topological signature arises (in the mean) even when there
are just a few images for each object. It is also shown that the mean pair
separation histogram technique works, and that it is a suitable approach for
studying the topological signatures of RW universes as well as the role of
non-translational isometries.
| [
{
"created": "Sat, 13 Nov 1999 17:24:00 GMT",
"version": "v1"
},
{
"created": "Fri, 30 Mar 2001 19:17:19 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Gomero",
"G. I.",
""
],
[
"Reboucas",
"M. J.",
""
],
[
"Teixeira",
"A. F. F.",
""
]
] | Two procedures for obtaining (extracting and constructing) the topological signature of any multiply connected Robertson-Walker (RW) universe are presented. It is shown through computer-aided simulations that both approaches give rise to the same topological signature for a multiply connected flat RW universe. The strength of these approaches is illustrated by extracting the topological signatures of a flat ($k=0$), an elliptic ($k=1$), and a hyperbolic ($k=-1$) multiply connected RW universes. We also show how separated contributions of the covering isometries add up to form the topological signature of a RW flat universe. There emerges from our theoretical results and simulations that the topological signature arises (in the mean) even when there are just a few images for each object. It is also shown that the mean pair separation histogram technique works, and that it is a suitable approach for studying the topological signatures of RW universes as well as the role of non-translational isometries. |
gr-qc/0701087 | Christian Boehmer | C. G. Boehmer | The Einstein-Elko system -- Can dark matter drive inflation? | 24 pages | AnnalenPhys.16:325-341,2007 | 10.1002/andp.200610237 | null | gr-qc astro-ph hep-th | null | Recently, a spin one half matter field with mass dimension one was
discovered, called Elko spinors. The present work shows how to introduce these
fields into a curved spacetime by the standard covariantisation scheme. After
formulating the coupled Einstein-Elko field equations, the spacetime is assumed
to be homogeneous and isotropic in order to simplify the resulting field
equations. Analytical ghost Elko solutions are constructed which have vanishing
energy-momentum tensor without and with cosmological constant. The cosmological
Elko theory is finally related to the standard scalar field theory with self
interaction that gives rise to inflation and it is pointed out that the Elko
spinors are not only prime dark matter candidates but also prime candidates for
inflation.
| [
{
"created": "Tue, 16 Jan 2007 00:58:27 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Boehmer",
"C. G.",
""
]
] | Recently, a spin one half matter field with mass dimension one was discovered, called Elko spinors. The present work shows how to introduce these fields into a curved spacetime by the standard covariantisation scheme. After formulating the coupled Einstein-Elko field equations, the spacetime is assumed to be homogeneous and isotropic in order to simplify the resulting field equations. Analytical ghost Elko solutions are constructed which have vanishing energy-momentum tensor without and with cosmological constant. The cosmological Elko theory is finally related to the standard scalar field theory with self interaction that gives rise to inflation and it is pointed out that the Elko spinors are not only prime dark matter candidates but also prime candidates for inflation. |
1005.3403 | Subenoy Chakraborty | Nairwita Mazumder, Subenoy Chakraborty | Validity of the Generalized Second Law of Thermodynamics of the Universe
Bounded by the Event Horizon in Holographic Dark Energy Model | 8 pages | Gen.Rel.Grav.42:813-820,2010 | 10.1007/s10714-009-0881-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this letter, we investigate the validity of the generalized second law of
thermodynamics of the universe bounded by the event horizon in the holographic
dark energy model. The universe is chosen to be homogeneous and isotropic and
the validity of the first law has been assumed here. The matter in the universe
is taken in the form of non-interacting two fluid system- one component is the
holographic dark energy model and the other component is in the form of dust.
| [
{
"created": "Wed, 19 May 2010 10:22:30 GMT",
"version": "v1"
}
] | 2010-11-04 | [
[
"Mazumder",
"Nairwita",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | In this letter, we investigate the validity of the generalized second law of thermodynamics of the universe bounded by the event horizon in the holographic dark energy model. The universe is chosen to be homogeneous and isotropic and the validity of the first law has been assumed here. The matter in the universe is taken in the form of non-interacting two fluid system- one component is the holographic dark energy model and the other component is in the form of dust. |
1108.6325 | Alexis Larranaga PhD | Alexis Larranaga | A Rotating Charged Black Hole Solution in f(R) Gravity | 9 pages, no figures | Pramana Journal of Physics 78, 5. 697-704 (2012) | 10.1007/s12043-012-0278-5 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the context of f(R) theories of gravity, we address the problem of finding
a rotating charged black hole solution in the case of constant curvature. The
new metric is obtained by solving the field equations and we show that the
behavior of it is typical of a rotating charged source. In addition, we analyze
the thermodynamics of the new black hole. The results ensures that the
thermodynamical properties in f(R) gravities are qualitatively similar to those
of standard General Relativity.
| [
{
"created": "Wed, 31 Aug 2011 19:08:26 GMT",
"version": "v1"
}
] | 2015-05-30 | [
[
"Larranaga",
"Alexis",
""
]
] | In the context of f(R) theories of gravity, we address the problem of finding a rotating charged black hole solution in the case of constant curvature. The new metric is obtained by solving the field equations and we show that the behavior of it is typical of a rotating charged source. In addition, we analyze the thermodynamics of the new black hole. The results ensures that the thermodynamical properties in f(R) gravities are qualitatively similar to those of standard General Relativity. |
1605.09685 | Valentin Rudenko | V.V. Kulagin, S.I. Oreshkin, S.M. Popov, V.N. Rudenko, M.N. Skvortsov,
I.S. Yudin | Opto acoustical gravitational bar detector with cryogenic mirrors | 9 pages, 5 figures | null | 10.1134/S0202289316040113 | null | gr-qc physics.ins-det | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Enhancing of sensitivity of the opto-acoustical gravitational wave (GW)
antenna OGRAN installed in the underground facilities of Baksan Neutrino
Observatory is analyzed. Calculations are presented showing a sensitivity
improving on two orders of value after a cooling the solid body acoustical part
of the antenna to the nitrogen temperature. A possibility of keeping of the
same optical scheme of the antenna at low temperature is discussed. Design of
modernized construction for cryogenic version of the antenna OGRAN is
described. Test experiments with cooled pilot model carrying cryogenic mirrors
illuminated by the optical pump up to 0.5 W are presented.
| [
{
"created": "Tue, 31 May 2016 15:57:20 GMT",
"version": "v1"
}
] | 2016-12-07 | [
[
"Kulagin",
"V. V.",
""
],
[
"Oreshkin",
"S. I.",
""
],
[
"Popov",
"S. M.",
""
],
[
"Rudenko",
"V. N.",
""
],
[
"Skvortsov",
"M. N.",
""
],
[
"Yudin",
"I. S.",
""
]
] | Enhancing of sensitivity of the opto-acoustical gravitational wave (GW) antenna OGRAN installed in the underground facilities of Baksan Neutrino Observatory is analyzed. Calculations are presented showing a sensitivity improving on two orders of value after a cooling the solid body acoustical part of the antenna to the nitrogen temperature. A possibility of keeping of the same optical scheme of the antenna at low temperature is discussed. Design of modernized construction for cryogenic version of the antenna OGRAN is described. Test experiments with cooled pilot model carrying cryogenic mirrors illuminated by the optical pump up to 0.5 W are presented. |
2001.11376 | Hernando Quevedo | Servando V. Serdio and Hernando Quevedo | Singularity theorems in Schwarzschild spacetimes | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a review of the two prominent singularity theorems due to Penrose
and Hawking, as well as their physical interpretation. Their usage is discussed
in detail for the Schwarzschild spacetime with positive and negative mass.
First, we present a detailed mathematical proof to formally guarantee the
existence of a singularity of geodesic incompleteness for the case of positive
mass. Second, we discuss the applicability of the mathematical tools used by
the theorems in the negative mass case. The physical implications of the
validity or inconsistency of the hypotheses of such theorems on the latter
case, are also exhibited. As far as this analysis is concerned, some clues are
produced regarding future research that could result in general properties for
naked singularities.
| [
{
"created": "Thu, 30 Jan 2020 14:56:30 GMT",
"version": "v1"
}
] | 2020-01-31 | [
[
"Serdio",
"Servando V.",
""
],
[
"Quevedo",
"Hernando",
""
]
] | We present a review of the two prominent singularity theorems due to Penrose and Hawking, as well as their physical interpretation. Their usage is discussed in detail for the Schwarzschild spacetime with positive and negative mass. First, we present a detailed mathematical proof to formally guarantee the existence of a singularity of geodesic incompleteness for the case of positive mass. Second, we discuss the applicability of the mathematical tools used by the theorems in the negative mass case. The physical implications of the validity or inconsistency of the hypotheses of such theorems on the latter case, are also exhibited. As far as this analysis is concerned, some clues are produced regarding future research that could result in general properties for naked singularities. |
2208.01992 | Diego Fern\'andez-Silvestre | Diego Fern\'andez-Silvestre, Michael R. R. Good, Eric V. Linder | Upon the horizon's verge: Thermal particle creation between and
approaching horizons | 10 pages, 4 figures | Class. Quantum Grav. 39 235008 (2022) | 10.1088/1361-6382/ac9d1b | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Quantum particle creation from spacetime horizons, or accelerating boundaries
in the dynamical Casimir effect, can have an equilibrium, or thermal,
distribution. Using an accelerating boundary in flat spacetime (moving mirror),
we investigate the production of thermal energy flux despite non-equilibrium
accelerations, the evolution between equilibrium states, and the "interference"
between horizons. In particular, this allows us to give a complete solution to
the particle spectrum of the accelerated boundary correspondence with
Schwarzschild-de Sitter spacetime.
| [
{
"created": "Wed, 3 Aug 2022 11:38:03 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Nov 2022 09:30:36 GMT",
"version": "v2"
}
] | 2022-11-15 | [
[
"Fernández-Silvestre",
"Diego",
""
],
[
"Good",
"Michael R. R.",
""
],
[
"Linder",
"Eric V.",
""
]
] | Quantum particle creation from spacetime horizons, or accelerating boundaries in the dynamical Casimir effect, can have an equilibrium, or thermal, distribution. Using an accelerating boundary in flat spacetime (moving mirror), we investigate the production of thermal energy flux despite non-equilibrium accelerations, the evolution between equilibrium states, and the "interference" between horizons. In particular, this allows us to give a complete solution to the particle spectrum of the accelerated boundary correspondence with Schwarzschild-de Sitter spacetime. |
2207.13009 | Changfu Shi | Shuo Sun, Changfu Shi, Jian-dong Zhang and Jianwei Mei | Detecting the gravitational wave memory effect with TianQin | 14 pages, 9 figures | Phys. Rev. D 107, 044023 (2023) | 10.1103/PhysRevD.107.044023 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The gravitational wave memory effect is a prediction of general relativity.
The presence of memory effect in gravitational wave signals not only provides
the chance to test an important aspect of general relativity, but also
represents a potentially non-negligible contribution to the waveform for
certain gravitational wave events. In this paper, we study the prospect of
detecting the gravitational wave memory effect directly with the planned
space-based gravitational wave detector -- TianQin. We find that during its 5
years operation, for the gravitational wave signals that could be detected by
TianQin, about $0.5\sim2.0$ signals may contain displacement memory effect with
signal-to-noise ratios (SNRs) greater than 3. This suggests that the chance for
TianQin to detect the displacement memory effect directly is low but not fully
negligible. In contrast, the chance to detect the spin memory is negligible. We
also study that in which parameter space, the memory effect is expected to be
significant in waveform modeling.
| [
{
"created": "Tue, 26 Jul 2022 16:17:35 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Feb 2023 03:47:39 GMT",
"version": "v2"
}
] | 2023-02-17 | [
[
"Sun",
"Shuo",
""
],
[
"Shi",
"Changfu",
""
],
[
"Zhang",
"Jian-dong",
""
],
[
"Mei",
"Jianwei",
""
]
] | The gravitational wave memory effect is a prediction of general relativity. The presence of memory effect in gravitational wave signals not only provides the chance to test an important aspect of general relativity, but also represents a potentially non-negligible contribution to the waveform for certain gravitational wave events. In this paper, we study the prospect of detecting the gravitational wave memory effect directly with the planned space-based gravitational wave detector -- TianQin. We find that during its 5 years operation, for the gravitational wave signals that could be detected by TianQin, about $0.5\sim2.0$ signals may contain displacement memory effect with signal-to-noise ratios (SNRs) greater than 3. This suggests that the chance for TianQin to detect the displacement memory effect directly is low but not fully negligible. In contrast, the chance to detect the spin memory is negligible. We also study that in which parameter space, the memory effect is expected to be significant in waveform modeling. |
gr-qc/0205083 | Lars Andersson | Lars Andersson | Construction of hyperboloidal initial data | Talk given at the Workshop on the Conformal Structure of Space-Times,
T\"ubingen, April 2--4, 2001 | Lect.Notes Phys. 604 (2002) 183-194 | null | null | gr-qc | null | I describe the conformal method for constructing solutions of the
hyperboloidal constraint equations as well as the conditions needed on the free
data in order to have regularity up to boundary for the solutions to the
constraint equations. A brief discussion of the Einstein evolution equations in
the unphysical setting is given.
| [
{
"created": "Sat, 18 May 2002 20:43:55 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Andersson",
"Lars",
""
]
] | I describe the conformal method for constructing solutions of the hyperboloidal constraint equations as well as the conditions needed on the free data in order to have regularity up to boundary for the solutions to the constraint equations. A brief discussion of the Einstein evolution equations in the unphysical setting is given. |
2205.01712 | Marco de Cesare | Marco de Cesare, Roberto Oliveri | Evolving black hole with scalar field accretion | 13 pages, 1 figure | Phys.Rev.D 106 (2022) 4, 044033 | 10.1103/PhysRevD.106.044033 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain approximate analytical solutions of the Einstein equations close to
the trapping horizon for a dynamical spherically symmetric black hole in the
presence of a minimally coupled self-interacting scalar field. This is made
possible by a new parametrization of the metric, in which the displacement from
the horizon as well as its expansion rate feature explicitly. Our results are
valid in a neighbourhood of the horizon and hold for any scalar field potential
and spacetime asymptotics. An exact equation for the accretion rate is also
obtained, which generalizes the standard Bondi formula. We also develop a
dynamical system approach to study near-equilibrium black holes; using this
formalism, we focus on a simple model to show that the near-equilibrium
dynamics is characterised by scaling relations among dynamical variables.
Moreover, we show that solutions with purely ingoing energy-momentum flux never
reach equilibrium.
| [
{
"created": "Tue, 3 May 2022 18:21:45 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Sep 2022 11:42:14 GMT",
"version": "v2"
}
] | 2022-09-15 | [
[
"de Cesare",
"Marco",
""
],
[
"Oliveri",
"Roberto",
""
]
] | We obtain approximate analytical solutions of the Einstein equations close to the trapping horizon for a dynamical spherically symmetric black hole in the presence of a minimally coupled self-interacting scalar field. This is made possible by a new parametrization of the metric, in which the displacement from the horizon as well as its expansion rate feature explicitly. Our results are valid in a neighbourhood of the horizon and hold for any scalar field potential and spacetime asymptotics. An exact equation for the accretion rate is also obtained, which generalizes the standard Bondi formula. We also develop a dynamical system approach to study near-equilibrium black holes; using this formalism, we focus on a simple model to show that the near-equilibrium dynamics is characterised by scaling relations among dynamical variables. Moreover, we show that solutions with purely ingoing energy-momentum flux never reach equilibrium. |
1309.1857 | Ai WenYuan | Wen-Yuan Ai, Hua Chen, Xian-Ru Hu, Jian-Bo Deng | Generalized Holographic Equipartition for Friedmann-Robertson-Walker
Universes | removed the section of de Sitter universe and so tile changed, to be
published in Gen. Rel. Grav | Gen Relativ Gravit (2014) 46:1680 | 10.1007/s10714-014-1680-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The novel idea that spatial expansion of our universe can be regarded as the
consequence of the emergence of space was proposed by Padmanabhan. By using of
the basic law governing the emergence, which Padmanabhan called holographic
equipartition, he also arrives at the Friedmann equation in a flat universe.
When generalized to other gravity theories, the holographic equipartition need
to be generalized with an expression of $f(\Delta N,N_{sur})$. In this paper,
we give general expressions of $f(\Delta N,N_{sur})$ for generalized
holographic equipartition which can be used to derive the Friedmann equations
of the Friedmann-Robertson-Walker universe with any spatial curvature in higher
(n+1)-dimensional Einstein gravity, Gauss-Bonnet gravity and more general
Lovelock gravity. The results support the viability of the perspective of
holographic equipartition.
| [
{
"created": "Sat, 7 Sep 2013 12:02:05 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Mar 2014 11:11:43 GMT",
"version": "v2"
},
{
"created": "Fri, 7 Mar 2014 13:39:07 GMT",
"version": "v3"
}
] | 2014-04-17 | [
[
"Ai",
"Wen-Yuan",
""
],
[
"Chen",
"Hua",
""
],
[
"Hu",
"Xian-Ru",
""
],
[
"Deng",
"Jian-Bo",
""
]
] | The novel idea that spatial expansion of our universe can be regarded as the consequence of the emergence of space was proposed by Padmanabhan. By using of the basic law governing the emergence, which Padmanabhan called holographic equipartition, he also arrives at the Friedmann equation in a flat universe. When generalized to other gravity theories, the holographic equipartition need to be generalized with an expression of $f(\Delta N,N_{sur})$. In this paper, we give general expressions of $f(\Delta N,N_{sur})$ for generalized holographic equipartition which can be used to derive the Friedmann equations of the Friedmann-Robertson-Walker universe with any spatial curvature in higher (n+1)-dimensional Einstein gravity, Gauss-Bonnet gravity and more general Lovelock gravity. The results support the viability of the perspective of holographic equipartition. |
2311.08822 | Hao Wang Hao Wang | Hao Wang, Yuan-Chuan Zou, Qing-Wen Wu, Yu Liu | Unveiling the Fingerprint of Eccentric Binary Black Hole Mergers | Submitted to PRL, comments are very welcome | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The orbital eccentricity plays a crucial role in shaping the dynamics of
binary black hole (BBH) mergers. Remarkably, our recent findings reveal a
universal oscillation in essential dynamic quantities: peak luminosity
$L_{\text{peak}}$, masses $M_f$, spins $\alpha_f$, and recoil velocity $V_f$ of
the final remnant black hole, as the initial eccentricity $e_0$ undergoes
variation. In this letter, by leveraging RIT's extensive numerical relativistic
simulations of nonspinning eccentric orbital BBH mergers, we not only confirm
the universal oscillation in peak amplitudes (including harmonic modes),
similar to the oscillations observed in $L_{\text{peak}}$, $M_f$, $\alpha_f$,
and $V_f$, but also make the first discovery of a ubiquitous spiral-like
internal fine structure that correlates $L_{\text{peak}}$, $M_f$, $\alpha_f$,
$V_f$, and peak amplitudes. This distinctive feature, which we term the
"fingerprint" of eccentric orbital BBH mergers, carries important implications
for unraveling the intricate dynamics and astrophysics associated with
eccentric orbital BBH mergers.
| [
{
"created": "Wed, 15 Nov 2023 09:51:39 GMT",
"version": "v1"
}
] | 2023-11-16 | [
[
"Wang",
"Hao",
""
],
[
"Zou",
"Yuan-Chuan",
""
],
[
"Wu",
"Qing-Wen",
""
],
[
"Liu",
"Yu",
""
]
] | The orbital eccentricity plays a crucial role in shaping the dynamics of binary black hole (BBH) mergers. Remarkably, our recent findings reveal a universal oscillation in essential dynamic quantities: peak luminosity $L_{\text{peak}}$, masses $M_f$, spins $\alpha_f$, and recoil velocity $V_f$ of the final remnant black hole, as the initial eccentricity $e_0$ undergoes variation. In this letter, by leveraging RIT's extensive numerical relativistic simulations of nonspinning eccentric orbital BBH mergers, we not only confirm the universal oscillation in peak amplitudes (including harmonic modes), similar to the oscillations observed in $L_{\text{peak}}$, $M_f$, $\alpha_f$, and $V_f$, but also make the first discovery of a ubiquitous spiral-like internal fine structure that correlates $L_{\text{peak}}$, $M_f$, $\alpha_f$, $V_f$, and peak amplitudes. This distinctive feature, which we term the "fingerprint" of eccentric orbital BBH mergers, carries important implications for unraveling the intricate dynamics and astrophysics associated with eccentric orbital BBH mergers. |
gr-qc/0310002 | Steven Carlip | M. Anderson, S. Carlip, J. Ratcliffe, S. Surya, S. Tschantz | Peaks in the Hartle-Hawking Wave Function from Sums over Topologies | 16 pages,LaTeX, no figures; v2: some changes coming from revision of
a math reference: wave function peaks sharp but not infinite; v3: added
paragraph in intro on interpretation of wave function | Class.Quant.Grav.21:729-742,2004 | 10.1088/0264-9381/21/2/025 | UCD-2003-10 | gr-qc astro-ph hep-th | null | Recent developments in ``Einstein Dehn filling'' allow the construction of
infinitely many Einstein manifolds that have different topologies but are
geometrically close to each other. Using these results, we show that for many
spatial topologies, the Hartle-Hawking wave function for a spacetime with a
negative cosmological constant develops sharp peaks at certain calculable
geometries. The peaks we find are all centered on spatial metrics of constant
negative curvature, suggesting a new mechanism for obtaining local homogeneity
in quantum cosmology.
| [
{
"created": "Wed, 1 Oct 2003 00:24:48 GMT",
"version": "v1"
},
{
"created": "Fri, 31 Oct 2003 21:22:21 GMT",
"version": "v2"
},
{
"created": "Wed, 19 Nov 2003 22:11:07 GMT",
"version": "v3"
}
] | 2010-04-28 | [
[
"Anderson",
"M.",
""
],
[
"Carlip",
"S.",
""
],
[
"Ratcliffe",
"J.",
""
],
[
"Surya",
"S.",
""
],
[
"Tschantz",
"S.",
""
]
] | Recent developments in ``Einstein Dehn filling'' allow the construction of infinitely many Einstein manifolds that have different topologies but are geometrically close to each other. Using these results, we show that for many spatial topologies, the Hartle-Hawking wave function for a spacetime with a negative cosmological constant develops sharp peaks at certain calculable geometries. The peaks we find are all centered on spatial metrics of constant negative curvature, suggesting a new mechanism for obtaining local homogeneity in quantum cosmology. |
1901.01596 | Iarley P. Lobo Dr | V. B. Bezerra, I. P. Lobo, H. F. Mota and C. R. Muniz | Landau Levels in the Presence of a Cosmic String in Rainbow Gravity | 21 pages, 6 figures. Accepted for publication in Annals of Physics | null | 10.1016/j.aop.2019.01.004 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we analyze the energy levels of a charged scalar particle
placed in the static cosmic string spacetime, under the action of a uniform
magnetic field parallel to the string, in the context of the semi-classical
approach of the rainbow gravity. Firstly, we focus on the non-relativistic
regime by solving the corresponding Schr\"{o}dinger equation, following by a
complete relativistic treatment of the problem in which we considered the
Klein-Gordon equation. In both cases we find exact expressions for the Landau
levels in terms of the rainbow functions, used to characterize a rainbow
gravity model. In order to achieve the results of this paper we considered
three different rainbow gravity models mostly used in the literature and
compare the resulting modifications in the Landau levels with the standard
case, namely without rainbow gravity.
| [
{
"created": "Sun, 6 Jan 2019 19:13:55 GMT",
"version": "v1"
}
] | 2019-01-08 | [
[
"Bezerra",
"V. B.",
""
],
[
"Lobo",
"I. P.",
""
],
[
"Mota",
"H. F.",
""
],
[
"Muniz",
"C. R.",
""
]
] | In this paper we analyze the energy levels of a charged scalar particle placed in the static cosmic string spacetime, under the action of a uniform magnetic field parallel to the string, in the context of the semi-classical approach of the rainbow gravity. Firstly, we focus on the non-relativistic regime by solving the corresponding Schr\"{o}dinger equation, following by a complete relativistic treatment of the problem in which we considered the Klein-Gordon equation. In both cases we find exact expressions for the Landau levels in terms of the rainbow functions, used to characterize a rainbow gravity model. In order to achieve the results of this paper we considered three different rainbow gravity models mostly used in the literature and compare the resulting modifications in the Landau levels with the standard case, namely without rainbow gravity. |
2404.18741 | Nikolaos Mavromatos | Nick E. Mavromatos, Panagiotis Dorlis, Sotirios-Neilos Vlachos | Torsion-induced axions in string theory, quantum gravity and the
cosmological tensions | 23 pages latex, several pdf figures incorporated, uses special macros
(PoS). Invited plenary talk by NEM in Corfu Summer Institute 2023 Workshop on
the Standard Model and beyond, August 27-September 7 2023 | null | null | KCL-PH-TH/2024-21 | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the role of torsion in string theory on inducing pseudoscalar
degrees of freedom (axions), which in turn couple to (gravitational)
Chern-Simons (CS) anomalous terms. Such interactions can induce inflation, of
running vacuum type, not requiring external inflaton fields, through
condensation of the anomalous terms as a consequence of primordial chiral
gravitational-wave (GW) tensor perturbations in a weak-quantum gravity setting.
The presence of an UV cutoff for the GW quantum graviton modes opens up the
system, leading to a dissipative behaviour realised via the presence of non
trivial imaginary parts of the gravitational CS terms. The naive estimate of
the life time of inflation based on such imaginary parts, which afflict the
pertinent GW Hamiltonian, is quite consistent with the estimates of the
duration of inflation based on an analysis of the condensate-induced
linear-axion-potential by means of dynamical systems. Such quantum-gravity
effects can also contribute positively to the alleviation of cosmological
tensions if they survive today. In the talk we discuss the conditions under
which such a result may be achieved. We also discuss the potential role of
other axions in string theory, coming from compactification, in inducing
enhanced densities of primordial black holes during RVM inflation, thereby
contributing to significantly increased percentages of these black holes that
can play the role of dark matter components. Moreover, under certain
circumstances, that we shall discuss in some detail, it is also possible that
the initially massless torsion-induced axions can acquire a non-trivial mass
during the radiation era, thereby providing additional dark matter components
in the Universe. With regards to this aspect, we also emphasise the role of
massive right-handed neutrinos, provided that such excitations exist in the
relevant spectra.
| [
{
"created": "Mon, 29 Apr 2024 14:42:32 GMT",
"version": "v1"
}
] | 2024-04-30 | [
[
"Mavromatos",
"Nick E.",
""
],
[
"Dorlis",
"Panagiotis",
""
],
[
"Vlachos",
"Sotirios-Neilos",
""
]
] | We discuss the role of torsion in string theory on inducing pseudoscalar degrees of freedom (axions), which in turn couple to (gravitational) Chern-Simons (CS) anomalous terms. Such interactions can induce inflation, of running vacuum type, not requiring external inflaton fields, through condensation of the anomalous terms as a consequence of primordial chiral gravitational-wave (GW) tensor perturbations in a weak-quantum gravity setting. The presence of an UV cutoff for the GW quantum graviton modes opens up the system, leading to a dissipative behaviour realised via the presence of non trivial imaginary parts of the gravitational CS terms. The naive estimate of the life time of inflation based on such imaginary parts, which afflict the pertinent GW Hamiltonian, is quite consistent with the estimates of the duration of inflation based on an analysis of the condensate-induced linear-axion-potential by means of dynamical systems. Such quantum-gravity effects can also contribute positively to the alleviation of cosmological tensions if they survive today. In the talk we discuss the conditions under which such a result may be achieved. We also discuss the potential role of other axions in string theory, coming from compactification, in inducing enhanced densities of primordial black holes during RVM inflation, thereby contributing to significantly increased percentages of these black holes that can play the role of dark matter components. Moreover, under certain circumstances, that we shall discuss in some detail, it is also possible that the initially massless torsion-induced axions can acquire a non-trivial mass during the radiation era, thereby providing additional dark matter components in the Universe. With regards to this aspect, we also emphasise the role of massive right-handed neutrinos, provided that such excitations exist in the relevant spectra. |
2002.03362 | Ozay Gurtug | O.Gurtug and M.Mangut | Gravitational Lensing in a Model of Nonlinear Electrodynamics: The case
for electrically and magnetically charged compact objects | 11 pages 8 figures, final version got acceptance from Annalen der
Physik | Annalen der Physik, 2020 | 10.1002/andp.201900576 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper aims to investigate the astrophysical applicability of the
electrically and magnetically charged black hole solutions obtained in a model
of nonlinear electrodynamics proposed by Kruglov (Ann. Phys. Berlin 2017, 529,
170073). Theoretical calculations of the bending angles and gravitational
redshifts from the theory of general relativity are studied numerically by
using the stellar data of charged compact objects and a hypothetical quark star
model. Calculations have revealed that although the theoretical outcomes differ
from the linear Maxwell case, the plotted bending angles coincide with the
linear case and it becomes hard to identify the effect of nonlinearity.
However, the calculation of the redshift has shown that while the increase in
the electric field leads to a decrease in the gravitational redshift,the
presence of the strong magnetic field contributes to the gravitational redshift
in an increasing manner.
| [
{
"created": "Sun, 9 Feb 2020 13:44:12 GMT",
"version": "v1"
}
] | 2020-02-18 | [
[
"Gurtug",
"O.",
""
],
[
"Mangut",
"M.",
""
]
] | This paper aims to investigate the astrophysical applicability of the electrically and magnetically charged black hole solutions obtained in a model of nonlinear electrodynamics proposed by Kruglov (Ann. Phys. Berlin 2017, 529, 170073). Theoretical calculations of the bending angles and gravitational redshifts from the theory of general relativity are studied numerically by using the stellar data of charged compact objects and a hypothetical quark star model. Calculations have revealed that although the theoretical outcomes differ from the linear Maxwell case, the plotted bending angles coincide with the linear case and it becomes hard to identify the effect of nonlinearity. However, the calculation of the redshift has shown that while the increase in the electric field leads to a decrease in the gravitational redshift,the presence of the strong magnetic field contributes to the gravitational redshift in an increasing manner. |
1606.00710 | Anatoly Shabad | Anatoly Shabad | A different interpretation of "Measuring propagation speed of Coulomb
fields" by R. de Sangro, G. Finocchiaro, P. Patteri, M. Piccolo, G. Pizzella | Comment on a work published in Eur. Phys. J. C, 3 pages | Eur. Phys. J. C (2016) 76:508 | 10.1140/epjc/s10052-016-4343-y | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We claim that the anti-relativistic statement in de Sangro et al., Eur. Phys.
J. C 75, 137 (2015) that the Coulomb field of a moving charge propagates
rigidly with it, cannot as a matter of fact be inferred from the measurements
reported in that reference. Registered is not the passing of the Coulomb disk,
but the acceleration-dependent part of the Lienard-Wiechert field.
| [
{
"created": "Sun, 29 May 2016 19:51:31 GMT",
"version": "v1"
}
] | 2016-11-22 | [
[
"Shabad",
"Anatoly",
""
]
] | We claim that the anti-relativistic statement in de Sangro et al., Eur. Phys. J. C 75, 137 (2015) that the Coulomb field of a moving charge propagates rigidly with it, cannot as a matter of fact be inferred from the measurements reported in that reference. Registered is not the passing of the Coulomb disk, but the acceleration-dependent part of the Lienard-Wiechert field. |
1410.7733 | Luis Nunez A | Guillermo A. Gonzalez, Anamaria Navarro, Luis A. Nunez | Cracking isotropic and anisotropic relativistic spheres | 17 pages, 4 figures. New examples and corrected typos | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore the influence of density fluctuations on isotropic and anisotropic
configurations, extending the concept of cracking for general relativistic
fluid spheres. This concept, conceived to describe the behaviour of anisotropic
matter distributions just after its departure from equilibrium, could provide
some insight on potential instabilities and future evolution of relativistic
fluids. We have refined the idea of cracking, considering local fluctuations
--represented by any function of compact support defined in a closed interval--
and their effect on the state variables and their gradients through
"barotropic" equations of state, $P = P(\rho)$ and $P_{\perp}=
P_{\perp}(\rho)$. Under this approach it is found that both isotropic and
anisotropic models could exhibit cracking (or overturning), and that previously
crackable anisotropic models become uncrackable.
| [
{
"created": "Tue, 28 Oct 2014 19:00:48 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Nov 2016 02:58:05 GMT",
"version": "v2"
}
] | 2016-11-16 | [
[
"Gonzalez",
"Guillermo A.",
""
],
[
"Navarro",
"Anamaria",
""
],
[
"Nunez",
"Luis A.",
""
]
] | We explore the influence of density fluctuations on isotropic and anisotropic configurations, extending the concept of cracking for general relativistic fluid spheres. This concept, conceived to describe the behaviour of anisotropic matter distributions just after its departure from equilibrium, could provide some insight on potential instabilities and future evolution of relativistic fluids. We have refined the idea of cracking, considering local fluctuations --represented by any function of compact support defined in a closed interval-- and their effect on the state variables and their gradients through "barotropic" equations of state, $P = P(\rho)$ and $P_{\perp}= P_{\perp}(\rho)$. Under this approach it is found that both isotropic and anisotropic models could exhibit cracking (or overturning), and that previously crackable anisotropic models become uncrackable. |
2003.10960 | Yu-Xiao Liu | Yu-Peng Zhang, Shao-Wen Wei, Yu-Xiao Liu | Spinning test particle in four-dimensional Einstein-Gauss-Bonnet Black
Hole | 10 pages, 5 figures | Universe 6 (2020) 8, 103 | 10.3390/universe6080103 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate the motion of a classical spinning test
particle orbiting around a static spherically symmetric black hole in a novel
four-dimensional Einstein-Gauss-Bonnet gravity [D. Glavan and C. Lin, Phys.
Rev. Lett. 124, 081301 (2020)]. We find that the effective potential of a
spinning test particle in the background of the black hole has two minima when
the Gauss-Bonnet coupling parameter $\alpha$ is nearly in a special range
$-6.1<\alpha/M^2<-2$ ($M$ is the mass of the black hole), which means such
particle can be in two separate orbits with the same spin angular momentum and
orbital angular momentum. We also investigate the innermost stable circular
orbits of the spinning test particle and find that the effect of the particle
spin on the the innermost stable circular is similar to the case of the
four-dimensional black hole in general relativity.
| [
{
"created": "Tue, 24 Mar 2020 16:38:04 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Apr 2020 07:38:39 GMT",
"version": "v2"
},
{
"created": "Fri, 29 Apr 2022 03:47:47 GMT",
"version": "v3"
}
] | 2022-05-02 | [
[
"Zhang",
"Yu-Peng",
""
],
[
"Wei",
"Shao-Wen",
""
],
[
"Liu",
"Yu-Xiao",
""
]
] | In this paper, we investigate the motion of a classical spinning test particle orbiting around a static spherically symmetric black hole in a novel four-dimensional Einstein-Gauss-Bonnet gravity [D. Glavan and C. Lin, Phys. Rev. Lett. 124, 081301 (2020)]. We find that the effective potential of a spinning test particle in the background of the black hole has two minima when the Gauss-Bonnet coupling parameter $\alpha$ is nearly in a special range $-6.1<\alpha/M^2<-2$ ($M$ is the mass of the black hole), which means such particle can be in two separate orbits with the same spin angular momentum and orbital angular momentum. We also investigate the innermost stable circular orbits of the spinning test particle and find that the effect of the particle spin on the the innermost stable circular is similar to the case of the four-dimensional black hole in general relativity. |
gr-qc/0010098 | Jerome Martin | Richard Kerner, Jerome Martin, Salvatore Mignemi and Jan-Willem van
Holten | Geodesic Deviation in Kaluza-Klein Theories | 5 pages, Revtex, 1 figure. To appear in Phys. Rev. D (Brief Report) | Phys.Rev. D63 (2001) 027502 | 10.1103/PhysRevD.63.027502 | null | gr-qc hep-th | null | We study in detail the equations of the geodesic deviation in
multidimensional theories of Kaluza-Klein type. We show that their
4-dimensional space-time projections are identical with the equations obtained
by direct variation of the usual geodesic equation in the presence of the
Lorentz force, provided that the fifth component of the deviation vector
satisfies an extra constraint derived here.
| [
{
"created": "Thu, 26 Oct 2000 12:24:44 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Kerner",
"Richard",
""
],
[
"Martin",
"Jerome",
""
],
[
"Mignemi",
"Salvatore",
""
],
[
"van Holten",
"Jan-Willem",
""
]
] | We study in detail the equations of the geodesic deviation in multidimensional theories of Kaluza-Klein type. We show that their 4-dimensional space-time projections are identical with the equations obtained by direct variation of the usual geodesic equation in the presence of the Lorentz force, provided that the fifth component of the deviation vector satisfies an extra constraint derived here. |
2104.09339 | R. K. L. Lo | Rico K. L. Lo and Ignacio Magana Hernandez | Bayesian statistical framework for identifying strongly lensed
gravitational-wave signals | 26 pages, 14 figures | Phys. Rev. D 107, 123015 (2023) | 10.1103/PhysRevD.107.123015 | null | gr-qc astro-ph.IM | http://creativecommons.org/licenses/by-nc-sa/4.0/ | It is expected that gravitational waves, similar to electromagnetic waves,
can be gravitationally lensed by intervening matters, producing multiple
instances of the same signal arriving at different times from different
apparent luminosity distances with different phase shifts compared to the
un-lensed signal due to lensing. If unaccounted for, these lensed signals will
masquerade as separate systems with higher mass and lower redshift. Here we
present a Bayesian statistical framework for identifying strongly-lensed
gravitational-wave signals that incorporates astrophysical information and
accounts for selection effects. We also propose a two-step hierarchical
analysis for more efficient computations of the probabilities and inferences of
source parameters free from bias introduced by lensing. We show with examples
on how changing the astrophysical models could shift one's interpretation on
the origin of the observed gravitational waves, and possibly lead to
indisputable evidence of strong lensing of the observed waves. In addition, we
demonstrate the improvement in the sky localization of the source of the lensed
signals, and in some cases the identification of the Morse indices of the
lensed signals. If confirmed, lensed gravitational waves will allow us to probe
the Universe at higher redshift, and to constrain the polarization contents of
the waves with fewer detectors.
| [
{
"created": "Mon, 19 Apr 2021 14:25:01 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Jun 2023 00:41:26 GMT",
"version": "v2"
}
] | 2023-06-14 | [
[
"Lo",
"Rico K. L.",
""
],
[
"Hernandez",
"Ignacio Magana",
""
]
] | It is expected that gravitational waves, similar to electromagnetic waves, can be gravitationally lensed by intervening matters, producing multiple instances of the same signal arriving at different times from different apparent luminosity distances with different phase shifts compared to the un-lensed signal due to lensing. If unaccounted for, these lensed signals will masquerade as separate systems with higher mass and lower redshift. Here we present a Bayesian statistical framework for identifying strongly-lensed gravitational-wave signals that incorporates astrophysical information and accounts for selection effects. We also propose a two-step hierarchical analysis for more efficient computations of the probabilities and inferences of source parameters free from bias introduced by lensing. We show with examples on how changing the astrophysical models could shift one's interpretation on the origin of the observed gravitational waves, and possibly lead to indisputable evidence of strong lensing of the observed waves. In addition, we demonstrate the improvement in the sky localization of the source of the lensed signals, and in some cases the identification of the Morse indices of the lensed signals. If confirmed, lensed gravitational waves will allow us to probe the Universe at higher redshift, and to constrain the polarization contents of the waves with fewer detectors. |
2204.00968 | Salvatore Vitale | Salvatore Vitale, Sylvia Biscoveanu, Colm Talbot | The orientations of the binary black holes in GWTC-3 | 5 pages, 3 figures, a lot of fun | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is expected that the orbital planes of gravitational-wave (GW) sources are
isotropically distributed. However, both physical and technical factors, such
as alternate theories of gravity with birefringence, catalog contamination, and
search algorithm limitations, could result in inferring a non-isotropic
distribution. Showing that the inferred astrophysical distribution of the
orbital orientations is indeed isotropic can thus be used to rule out some
violations of general relativity, as a null test about the purity of the GW
catalog sample, and as a check that selection effects are being properly
accounted for. We augment the default mass/spins/redshift model used by the
LIGO-Virgo-KAGRA Collaboration in their most recent analysis to also measure
the astrophysical distribution of orbital orientations. We show that the 69
binary black holes in GWTC-3 are consistent with having random orbital
orientations. The inferred distribution is highly symmetric around $\pi/2$,
with skewness $\mathcal{S}_{\rm{post}}=0.01^{+0.17}_{-0.17}$. Meanwhile, the
median of the inferred distribution has a Jensen-Shannon divergence of
$1.4\times 10^{-4}$ bits when compared to the expected isotropic distribution.
| [
{
"created": "Sun, 3 Apr 2022 01:38:48 GMT",
"version": "v1"
}
] | 2022-04-05 | [
[
"Vitale",
"Salvatore",
""
],
[
"Biscoveanu",
"Sylvia",
""
],
[
"Talbot",
"Colm",
""
]
] | It is expected that the orbital planes of gravitational-wave (GW) sources are isotropically distributed. However, both physical and technical factors, such as alternate theories of gravity with birefringence, catalog contamination, and search algorithm limitations, could result in inferring a non-isotropic distribution. Showing that the inferred astrophysical distribution of the orbital orientations is indeed isotropic can thus be used to rule out some violations of general relativity, as a null test about the purity of the GW catalog sample, and as a check that selection effects are being properly accounted for. We augment the default mass/spins/redshift model used by the LIGO-Virgo-KAGRA Collaboration in their most recent analysis to also measure the astrophysical distribution of orbital orientations. We show that the 69 binary black holes in GWTC-3 are consistent with having random orbital orientations. The inferred distribution is highly symmetric around $\pi/2$, with skewness $\mathcal{S}_{\rm{post}}=0.01^{+0.17}_{-0.17}$. Meanwhile, the median of the inferred distribution has a Jensen-Shannon divergence of $1.4\times 10^{-4}$ bits when compared to the expected isotropic distribution. |
gr-qc/0611052 | Raymond Burston | R. B. Burston and A. W. C. Lun | Covariant Schwarzschild perturbations I: Initial value formulation for
scalars of spin-weight -+ 2 | 17 pages. Submitted to Class. Quantum Grav | null | null | null | gr-qc | null | We consider full perturbations to a covariantly defined Schwarzschild
spacetime. By constructing complex quantities, we derive two decoupled,
covariant and gauge-invariant, wave-like equations for spin-weighted scalars.
These arise naturally from the Bianchi identities and comprise a covariant
representation of the Bardeen-Press equations for scalars with spin-weight
$\pm2$. Furthermore, the covariant and gauge-invariant 1+1+2 formalism is
employed, and consequently, the physical interpretation of the energy-momentum
perturbations is transparent. They are written explicitly in terms of the
energy-momentum specified on spacelike three-slices. Ultimately, a Cauchy
problem is constructed whereby, an initial three-slice may be perturbed by an
energy-momentum source, which induces resultant gravitational fields.
| [
{
"created": "Wed, 8 Nov 2006 11:58:22 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Burston",
"R. B.",
""
],
[
"Lun",
"A. W. C.",
""
]
] | We consider full perturbations to a covariantly defined Schwarzschild spacetime. By constructing complex quantities, we derive two decoupled, covariant and gauge-invariant, wave-like equations for spin-weighted scalars. These arise naturally from the Bianchi identities and comprise a covariant representation of the Bardeen-Press equations for scalars with spin-weight $\pm2$. Furthermore, the covariant and gauge-invariant 1+1+2 formalism is employed, and consequently, the physical interpretation of the energy-momentum perturbations is transparent. They are written explicitly in terms of the energy-momentum specified on spacelike three-slices. Ultimately, a Cauchy problem is constructed whereby, an initial three-slice may be perturbed by an energy-momentum source, which induces resultant gravitational fields. |
1806.05719 | Mayer Humi | Mayer Humi and John Roumas | Structure of Polytropic Stars in General Relativity | This is a replacement and major revision of arXiv:1605.08650 | null | 10.1007/s10509-019-3608-y | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The inner structure of a star or a primordial interstellar cloud is a major
topic in classical and relativistic physics. The impact that General
Relativistic principles have on this structure has been the subject of many
research papers. In this paper we consider within the context of General
Relativity a prototype model for this problem by assuming that a star consists
of polytropic gas. To justify this assumption we observe that stars undergo
thermodynamically irreversible processes and emit heat and radiation to their
surroundings. Due to the emission of this energy it is worthwhile to consider
an idealized model in which the gas is polytropic. To find interior solutions
to the Einstein equations of General Relativity in this setting we derive a
single equation for the cumulative mass distribution of the star and use
Tolman-Oppenheimer-Volkoff equation to derive formulas for the isentropic index
and coefficient. Using these formulas we present analytic and numerical
solutions for the polytropic structure of self-gravitating stars and examine
their stability. We prove also that when the thermodynamics of a star as
represented by the isentropic index and coefficient is known, the corresponding
matter density within the star is uniquely determined.
| [
{
"created": "Thu, 14 Jun 2018 19:56:11 GMT",
"version": "v1"
}
] | 2019-08-14 | [
[
"Humi",
"Mayer",
""
],
[
"Roumas",
"John",
""
]
] | The inner structure of a star or a primordial interstellar cloud is a major topic in classical and relativistic physics. The impact that General Relativistic principles have on this structure has been the subject of many research papers. In this paper we consider within the context of General Relativity a prototype model for this problem by assuming that a star consists of polytropic gas. To justify this assumption we observe that stars undergo thermodynamically irreversible processes and emit heat and radiation to their surroundings. Due to the emission of this energy it is worthwhile to consider an idealized model in which the gas is polytropic. To find interior solutions to the Einstein equations of General Relativity in this setting we derive a single equation for the cumulative mass distribution of the star and use Tolman-Oppenheimer-Volkoff equation to derive formulas for the isentropic index and coefficient. Using these formulas we present analytic and numerical solutions for the polytropic structure of self-gravitating stars and examine their stability. We prove also that when the thermodynamics of a star as represented by the isentropic index and coefficient is known, the corresponding matter density within the star is uniquely determined. |
1806.01577 | Mohamed Ould El Hadj | Antoine Folacci and Mohamed Ould El Hadj | Multipolar gravitational waveforms and ringdowns generated during the
plunge from the innermost stable circular orbit into a Schwarzschild black
hole | arXiv admin note: substantial text overlap with arXiv:1805.11950 v2:
Includes a comparison with results obtained in Refs. [19] and [20] and
matches the version to appear in PRD | Phys. Rev. D 98, 084008 (2018) | 10.1103/PhysRevD.98.084008 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the gravitational radiation emitted by a massive point particle
plunging from slightly below the innermost stable circular orbit into a
Schwarzschild black hole. We consider both even- and odd-parity perturbations
and describe them using the two gauge-invariant master functions of Cunningham,
Price, and Moncrief. We obtain, for arbitrary directions of observation and, in
particular, outside the orbital plane of the plunging particle, the regularized
multipolar waveforms, i.e., the waveforms constructed by summing over of a
large number of modes, and their unregularized counterparts constructed from
the quasinormal-mode spectrum. They are in excellent agreement and our results
permit us to especially emphasize the impact on the distortion of the waveforms
of (i) the harmonics beyond the dominant $(\ell=2,m=\pm 2)$ modes and (ii) the
direction of observation, and therefore the necessity to take them into account
in the analysis of the last phase of binary black hole coalescence.
| [
{
"created": "Tue, 5 Jun 2018 09:32:00 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Sep 2018 15:32:47 GMT",
"version": "v2"
}
] | 2018-10-08 | [
[
"Folacci",
"Antoine",
""
],
[
"Hadj",
"Mohamed Ould El",
""
]
] | We study the gravitational radiation emitted by a massive point particle plunging from slightly below the innermost stable circular orbit into a Schwarzschild black hole. We consider both even- and odd-parity perturbations and describe them using the two gauge-invariant master functions of Cunningham, Price, and Moncrief. We obtain, for arbitrary directions of observation and, in particular, outside the orbital plane of the plunging particle, the regularized multipolar waveforms, i.e., the waveforms constructed by summing over of a large number of modes, and their unregularized counterparts constructed from the quasinormal-mode spectrum. They are in excellent agreement and our results permit us to especially emphasize the impact on the distortion of the waveforms of (i) the harmonics beyond the dominant $(\ell=2,m=\pm 2)$ modes and (ii) the direction of observation, and therefore the necessity to take them into account in the analysis of the last phase of binary black hole coalescence. |
2402.02789 | Qiyuan Pan | Chengjia Chen, Qiyuan Pan and Jiliang Jing | Geometrically thick equilibrium tori around a Schwarzschild black hole
in swirling universes | 12 pages, 4 figures | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We study geometrically thick non-self gravitating equilibrium tori orbiting a
Schwarzschild black hole immersed in swirling universes. This solution is
axially symmetric and non-asymptotically flat, and its north and south
hemispheres spin in opposite directions. Due to repulsive effects arising from
the swirl of the background spacetime, the equilibrium torus exists only in the
case with the small swirling parameter. With the increase of the swirling
parameter, the disk structure becomes small and the excretion of matter near
the black hole becomes strong. Moreover, the odd $Z_2$ symmetry of spacetimes
originating from the swirling parameter yields that the orientation of closed
equipotential surfaces deviates away from the horizontal axis and the
corresponding disk does not longer possess the symmetry with respect to the
equatorial plane. These significant features could help to further understand
the equilibrium tori and geometrically thick accretion disks around black holes
in swirling universes.
| [
{
"created": "Mon, 5 Feb 2024 07:55:41 GMT",
"version": "v1"
}
] | 2024-02-06 | [
[
"Chen",
"Chengjia",
""
],
[
"Pan",
"Qiyuan",
""
],
[
"Jing",
"Jiliang",
""
]
] | We study geometrically thick non-self gravitating equilibrium tori orbiting a Schwarzschild black hole immersed in swirling universes. This solution is axially symmetric and non-asymptotically flat, and its north and south hemispheres spin in opposite directions. Due to repulsive effects arising from the swirl of the background spacetime, the equilibrium torus exists only in the case with the small swirling parameter. With the increase of the swirling parameter, the disk structure becomes small and the excretion of matter near the black hole becomes strong. Moreover, the odd $Z_2$ symmetry of spacetimes originating from the swirling parameter yields that the orientation of closed equipotential surfaces deviates away from the horizontal axis and the corresponding disk does not longer possess the symmetry with respect to the equatorial plane. These significant features could help to further understand the equilibrium tori and geometrically thick accretion disks around black holes in swirling universes. |
gr-qc/0208053 | Farhad Darabi | S. K. Moayedi, F. Darabi | Exact solutions of Dirac equation on a 2D gravitational background | 10 pages, title changed, content reduced, some references removed, To
be published in PLA | Phys.Lett.A322:173-178,2004 | 10.1016/j.physleta.2004.01.032 | null | gr-qc hep-th | null | We obtain classes of two dimensional static Lorentzian manifolds, which
through the supersymmetric formalism of quantum mechanics admit the exact
solvability of Dirac equation on these curved backgrounds. Specially in the
case of a modified supersymmetric harmonic oscillator the wave function and
energy spectrum of Dirac equation is given explicitly.
| [
{
"created": "Mon, 19 Aug 2002 06:25:43 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Jan 2004 06:58:39 GMT",
"version": "v2"
}
] | 2014-11-17 | [
[
"Moayedi",
"S. K.",
""
],
[
"Darabi",
"F.",
""
]
] | We obtain classes of two dimensional static Lorentzian manifolds, which through the supersymmetric formalism of quantum mechanics admit the exact solvability of Dirac equation on these curved backgrounds. Specially in the case of a modified supersymmetric harmonic oscillator the wave function and energy spectrum of Dirac equation is given explicitly. |
1605.08502 | Kai Lin | Jin Li, Kai Lin, Hao Wen and Wei-Liang Qian | Gravitational Quasinormal Modes of Regular Phantom Black Hole | null | Advances in High Energy Physics, Volume 2017 (2017), Article ID
5234214 | 10.1155/2017/5234214 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the gravitational quasi-normal modes (QNMs) for a type of
regular black hole (BH) known as phantom BH, which is a static self-gravitating
solution of a minimally coupled phantom scalar field with a potential. The
studies are carried out for three different spacetimes: asymptotically flat, de
Sitter (dS), and anti de Sitter (AdS). In order to consider the standard odd
parity and even parity of gravitational perturbations, the corresponding master
equations are derived. The QNMs are discussed by evaluating the temporal
evolution of the perturbation field which, in turn, provides direct information
on the stability of BH spacetime. It is found that in asymptotically flat, dS
and AdS spacetimes, the gravitational perturbations have similar
characteristics for both odd and even parities. The decay rate of perturbation
is strongly dependent on the scale parameter $b$, which measures the coupling
strength between phantom scalar field and the gravity. Furthermore, through the
analysis of Hawking radiation, it is shown that the thermodynamics of such
regular phantom BH is also influenced by $b$. The obtained results might shed
some light on the quantum interpretation of QNM perturbation.
| [
{
"created": "Fri, 27 May 2016 04:01:47 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Feb 2017 02:16:28 GMT",
"version": "v2"
}
] | 2017-02-20 | [
[
"Li",
"Jin",
""
],
[
"Lin",
"Kai",
""
],
[
"Wen",
"Hao",
""
],
[
"Qian",
"Wei-Liang",
""
]
] | We investigate the gravitational quasi-normal modes (QNMs) for a type of regular black hole (BH) known as phantom BH, which is a static self-gravitating solution of a minimally coupled phantom scalar field with a potential. The studies are carried out for three different spacetimes: asymptotically flat, de Sitter (dS), and anti de Sitter (AdS). In order to consider the standard odd parity and even parity of gravitational perturbations, the corresponding master equations are derived. The QNMs are discussed by evaluating the temporal evolution of the perturbation field which, in turn, provides direct information on the stability of BH spacetime. It is found that in asymptotically flat, dS and AdS spacetimes, the gravitational perturbations have similar characteristics for both odd and even parities. The decay rate of perturbation is strongly dependent on the scale parameter $b$, which measures the coupling strength between phantom scalar field and the gravity. Furthermore, through the analysis of Hawking radiation, it is shown that the thermodynamics of such regular phantom BH is also influenced by $b$. The obtained results might shed some light on the quantum interpretation of QNM perturbation. |
1409.4278 | David W. Tian | David Wenjie Tian, Ivan Booth | Friedmann equations from nonequilibrium thermodynamics of the Universe:
A unified formulation for modified gravity | 33 pages, to appear in Physical Review D, with three more subsections
on negative horizon temperature, self-inconsistency of f(R,G) gravity, and
dynamical Chern-Simons gravity; new references added | Physical Review D 90, 104042 (2014) | 10.1103/PhysRevD.90.104042 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Inspired by the Wald-Kodama entropy $S=A/(4G_{\text{eff}})$ where $A$ is the
horizon area and $G_{\text{eff}}$ is the effective gravitational coupling
strength in modified gravity with field equation $R_{\mu\nu}-Rg_{\mu\nu}/2=$
$8\pi G_{\text{eff}} T_{\mu\nu}^{\text{(eff)}}$, we develop a unified and
compact formulation in which the Friedmann equations can be derived from
thermodynamics of the Universe. The Hawking and Misner-Sharp masses are
generalized by replacing Newton's constant $G$ with $G_{\text{eff}}$, and the
unified first law of equilibrium thermodynamics is supplemented by a
nonequilibrium energy dissipation term $\mathcal{E}$ which arises from the
revised continuity equation of the perfect-fluid effective matter content and
is related to the evolution of $G_{\text{eff}}$. By identifying the mass as the
total internal energy, the unified first law for the interior and its smooth
transit to the apparent horizon yield both Friedmann equations, while the
nonequilibrium Clausius relation with entropy production for an isochoric
process provides an alternative derivation on the horizon. We also analyze the
equilibrium situation $G_{\text{eff}}=G=\text{constant}$, provide a viability
test of the generalized geometric masses, and discuss the
continuity/conservation equation. Finally, the general formulation is applied
to the FRW cosmology of minimally coupled $f(R)$, generalized Brans-Dicke,
scalar-tensor-chameleon, quadratic, $f(R,\mathcal{G})$ generalized Gauss-Bonnet
and dynamical Chern-Simons gravity. In these theories we also analyze the
$f(R)$-Brans-Dicke equivalence, find that the chameleon effect causes extra
energy dissipation and entropy production, geometrically reconstruct the mass
$\rho_m V$ for the physical matter content, and show the self-inconsistency of
$f(R,\mathcal{G})$ gravity in problems involving $G_{\text{eff}}$.
| [
{
"created": "Mon, 15 Sep 2014 14:44:43 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Oct 2014 21:26:39 GMT",
"version": "v2"
}
] | 2015-07-14 | [
[
"Tian",
"David Wenjie",
""
],
[
"Booth",
"Ivan",
""
]
] | Inspired by the Wald-Kodama entropy $S=A/(4G_{\text{eff}})$ where $A$ is the horizon area and $G_{\text{eff}}$ is the effective gravitational coupling strength in modified gravity with field equation $R_{\mu\nu}-Rg_{\mu\nu}/2=$ $8\pi G_{\text{eff}} T_{\mu\nu}^{\text{(eff)}}$, we develop a unified and compact formulation in which the Friedmann equations can be derived from thermodynamics of the Universe. The Hawking and Misner-Sharp masses are generalized by replacing Newton's constant $G$ with $G_{\text{eff}}$, and the unified first law of equilibrium thermodynamics is supplemented by a nonequilibrium energy dissipation term $\mathcal{E}$ which arises from the revised continuity equation of the perfect-fluid effective matter content and is related to the evolution of $G_{\text{eff}}$. By identifying the mass as the total internal energy, the unified first law for the interior and its smooth transit to the apparent horizon yield both Friedmann equations, while the nonequilibrium Clausius relation with entropy production for an isochoric process provides an alternative derivation on the horizon. We also analyze the equilibrium situation $G_{\text{eff}}=G=\text{constant}$, provide a viability test of the generalized geometric masses, and discuss the continuity/conservation equation. Finally, the general formulation is applied to the FRW cosmology of minimally coupled $f(R)$, generalized Brans-Dicke, scalar-tensor-chameleon, quadratic, $f(R,\mathcal{G})$ generalized Gauss-Bonnet and dynamical Chern-Simons gravity. In these theories we also analyze the $f(R)$-Brans-Dicke equivalence, find that the chameleon effect causes extra energy dissipation and entropy production, geometrically reconstruct the mass $\rho_m V$ for the physical matter content, and show the self-inconsistency of $f(R,\mathcal{G})$ gravity in problems involving $G_{\text{eff}}$. |
1109.0801 | Hiromi Saida | Hiromi Saida | Limit of Universality of Entropy-Area Law for Multi-Horizon Spacetimes | 44 pages, 4 figures. Invited as a chapter contribution to an edited
book, "Classical and Quantum Gravity: Theory, Analysis and Application",
2011, Nova Publ | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It may be a common understanding at present that, once event horizons are in
thermal equilibrium, the entropy-area law holds inevitably. However, no
rigorous verification is given to such a very strong universality of the law in
multi-horizon spacetimes. In this article, based on thermodynamically
consistent and rigorous discussion, we investigate thermodynamics of
Schwarzschild-deSitter spacetime in which the temperatures of two horizons are
different. We recognize that three independent state variables exist in
thermodynamics of the horizons. One of the three variables represents the
effect of "external gravity" acting on one horizon due to another one. Then we
find that thermodynamic formalism with three independent variables suggests the
breakdown of entropy-area law, and clarifies the necessary and sufficient
condition for the entropy-area law. As a by-product, the special role of
cosmological constant in thermodynamics of horizons is also revealed.
| [
{
"created": "Mon, 5 Sep 2011 05:30:47 GMT",
"version": "v1"
}
] | 2011-09-06 | [
[
"Saida",
"Hiromi",
""
]
] | It may be a common understanding at present that, once event horizons are in thermal equilibrium, the entropy-area law holds inevitably. However, no rigorous verification is given to such a very strong universality of the law in multi-horizon spacetimes. In this article, based on thermodynamically consistent and rigorous discussion, we investigate thermodynamics of Schwarzschild-deSitter spacetime in which the temperatures of two horizons are different. We recognize that three independent state variables exist in thermodynamics of the horizons. One of the three variables represents the effect of "external gravity" acting on one horizon due to another one. Then we find that thermodynamic formalism with three independent variables suggests the breakdown of entropy-area law, and clarifies the necessary and sufficient condition for the entropy-area law. As a by-product, the special role of cosmological constant in thermodynamics of horizons is also revealed. |
gr-qc/9603012 | BS Kay | Bernard S. Kay (York), Marek J. Radzikowski (York, Hamburg), Robert M.
Wald (Chicago) | Quantum Field Theory on Spacetimes with a Compactly Generated Cauchy
Horizon | 37 pages, LaTeX, uses latexsym and amsbsy, no figures; updated
version now published in Commun. Math. Phys.; no major revisions from
original version | Commun.Math.Phys.183:533-556,1997 | 10.1007/s002200050042 | null | gr-qc hep-th | null | We prove two theorems which concern difficulties in the formulation of the
quantum theory of a linear scalar field on a spacetime, (M,g_{ab}), with a
compactly generated Cauchy horizon. These theorems demonstrate the breakdown of
the theory at certain `base points' of the Cauchy horizon, which are defined as
`past terminal accumulation points' of the horizon generators. Thus, the
theorems may be interpreted as giving support to Hawking's `Chronology
Protection Conjecture', according to which the laws of physics prevent one from
manufacturing a `time machine'. Specifically, we prove: Theorem 1: There is no
extension to (M,g_{ab}) of the usual field algebra on the initial globally
hyperbolic region which satisfies the condition of F-locality at any base
point. In other words, any extension of the field algebra must, in any globally
hyperbolic neighbourhood of any base point, differ from the algebra one would
define on that neighbourhood according to the rules for globally hyperbolic
spacetimes. Theorem 2: The two-point distribution for any Hadamard state
defined on the initial globally hyperbolic region must (when extended to a
distributional bisolution of the covariant Klein-Gordon equation on the full
spacetime) be singular at every base point x in the sense that the difference
between this two point distribution and a local Hadamard distribution cannot be
given by a bounded function in any neighbourhood (in MXM) of (x,x). Theorem 2
implies quantities such as the renormalized expectation value of \phi^2 or of
the stress-energy tensor are necessarily ill-defined or singular at any base
point. The proofs rely on the `Propagation of Singularities' theorems of
Duistermaat and H\"ormander.
| [
{
"created": "Sun, 10 Mar 1996 21:54:24 GMT",
"version": "v1"
},
{
"created": "Thu, 8 May 1997 16:25:04 GMT",
"version": "v2"
}
] | 2010-11-19 | [
[
"Kay",
"Bernard S.",
"",
"York"
],
[
"Radzikowski",
"Marek J.",
"",
"York, Hamburg"
],
[
"Wald",
"Robert M.",
"",
"Chicago"
]
] | We prove two theorems which concern difficulties in the formulation of the quantum theory of a linear scalar field on a spacetime, (M,g_{ab}), with a compactly generated Cauchy horizon. These theorems demonstrate the breakdown of the theory at certain `base points' of the Cauchy horizon, which are defined as `past terminal accumulation points' of the horizon generators. Thus, the theorems may be interpreted as giving support to Hawking's `Chronology Protection Conjecture', according to which the laws of physics prevent one from manufacturing a `time machine'. Specifically, we prove: Theorem 1: There is no extension to (M,g_{ab}) of the usual field algebra on the initial globally hyperbolic region which satisfies the condition of F-locality at any base point. In other words, any extension of the field algebra must, in any globally hyperbolic neighbourhood of any base point, differ from the algebra one would define on that neighbourhood according to the rules for globally hyperbolic spacetimes. Theorem 2: The two-point distribution for any Hadamard state defined on the initial globally hyperbolic region must (when extended to a distributional bisolution of the covariant Klein-Gordon equation on the full spacetime) be singular at every base point x in the sense that the difference between this two point distribution and a local Hadamard distribution cannot be given by a bounded function in any neighbourhood (in MXM) of (x,x). Theorem 2 implies quantities such as the renormalized expectation value of \phi^2 or of the stress-energy tensor are necessarily ill-defined or singular at any base point. The proofs rely on the `Propagation of Singularities' theorems of Duistermaat and H\"ormander. |
1807.07407 | Mahouton J. Stephane Houndjo Dr | P. H. Logbo and M. J. S. Houndjo | Type IV singular bouncing cosmology from $f(T)$ Gravity | 9 pages, 3 figures. arXiv admin note: text overlap with
arXiv:1504.06866 by other authors | null | 10.1142/S0218271819501475 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate bouncing scenario in the modified $f(T)$ gravity, $T$ being
the torsion scalar. Attention is attached to the reconstruction of $f(T)$ able
to describe type IV singular bouncing evolution, where we adopt as assumption
that the bouncing and type IV singularity points coincide. In the context of
the reconstructed $f(T)$ model we calculate the Hubble slow-roll parameters in
order to determine the dynamical evolution of the cosmological system under
study. The results show that the Hubble slow-roll parameters become singular at
the type IV singularity indicating a dynamical instability. Moreover we perform
the stability analysis of the $f(T)$ gravity solution where, according to the
obtained result, the type IV singularity point is a saddle point in agreement
with the bounce scenario.
| [
{
"created": "Sat, 14 Jul 2018 16:51:58 GMT",
"version": "v1"
}
] | 2019-09-25 | [
[
"Logbo",
"P. H.",
""
],
[
"Houndjo",
"M. J. S.",
""
]
] | We investigate bouncing scenario in the modified $f(T)$ gravity, $T$ being the torsion scalar. Attention is attached to the reconstruction of $f(T)$ able to describe type IV singular bouncing evolution, where we adopt as assumption that the bouncing and type IV singularity points coincide. In the context of the reconstructed $f(T)$ model we calculate the Hubble slow-roll parameters in order to determine the dynamical evolution of the cosmological system under study. The results show that the Hubble slow-roll parameters become singular at the type IV singularity indicating a dynamical instability. Moreover we perform the stability analysis of the $f(T)$ gravity solution where, according to the obtained result, the type IV singularity point is a saddle point in agreement with the bounce scenario. |
1201.6164 | Scientific Information Service CERN | K. Enqvist (Univ. Helsinki and Helsinki Inst. Phys.) | Cosmological inflation | 9 pages, contribution to the 2010 European School of High-energy
Physics; 20 June - 3 July 2010, Raseborg, Finland | CERN Yellow Report CERN-2012-001, pp. 207-215 | null | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | The very basics of cosmological inflation are discussed. We derive the
equations of motion for the inflaton field, introduce the slow-roll parameters,
and present the computation of the inflationary perturbations and their
connection to the temperature fluctuations of the cosmic microwave background.
| [
{
"created": "Mon, 30 Jan 2012 10:51:17 GMT",
"version": "v1"
}
] | 2012-01-31 | [
[
"Enqvist",
"K.",
"",
"Univ. Helsinki and Helsinki Inst. Phys."
]
] | The very basics of cosmological inflation are discussed. We derive the equations of motion for the inflaton field, introduce the slow-roll parameters, and present the computation of the inflationary perturbations and their connection to the temperature fluctuations of the cosmic microwave background. |
1412.8404 | Carlos Hidalgo | Roberto A. Sussman, Juan Carlos Hidalgo, Peter K. S. Dunsby, Gabriel
German | On spherical dust fluctuations: the exact vs. the perturbative approach | V2: References added and typos corrected. Version accepted for
publication in PRD | null | 10.1103/PhysRevD.91.063512 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the relation between the dynamics of Lema\^{\i}tre-Tolman-Bondi
(LTB) dust models (with and without $\Lambda$) and the dynamics of dust
perturbations in two of the more familiar formalisms used in cosmology: the
metric based Cosmological Perturbation Theory (CPT) and the Covariant Gauge
Invariant (GIC) perturbations. For this purpose we recast the evolution of LTB
models in terms of a covariant and gauge invariant formalism of local and
non-local "exact fluctuations " on a Friedmann-Lema\^{\i}tre-Robertson-Walker
(FLRW) background defined by suitable averages of covariant scalars. We examine
the properties of these fluctuations, which can be defined for a confined
comoving domain or for an asymptotic domain extending to whole time slices. In
particular, the non-local density fluctuation provides a covariant and precise
definition for the notion of the "density contrast ". We show that in their
linear regime these LTB exact fluctuations (local and non-local) are fully
equivalent to the conventional cosmological perturbations in the
synchronous-comoving gauge of CPT and to GIC perturbations. As an immediate
consequence, we show the time-invariance of the spatial curvature perturbation
in a simple form. The present work may provide important theoretical
connections between the exact and perturbative (linear or no-linear) approach
to the dynamics of dust sources in General Relativity.
| [
{
"created": "Mon, 29 Dec 2014 17:43:19 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Feb 2015 22:00:17 GMT",
"version": "v2"
}
] | 2015-06-23 | [
[
"Sussman",
"Roberto A.",
""
],
[
"Hidalgo",
"Juan Carlos",
""
],
[
"Dunsby",
"Peter K. S.",
""
],
[
"German",
"Gabriel",
""
]
] | We examine the relation between the dynamics of Lema\^{\i}tre-Tolman-Bondi (LTB) dust models (with and without $\Lambda$) and the dynamics of dust perturbations in two of the more familiar formalisms used in cosmology: the metric based Cosmological Perturbation Theory (CPT) and the Covariant Gauge Invariant (GIC) perturbations. For this purpose we recast the evolution of LTB models in terms of a covariant and gauge invariant formalism of local and non-local "exact fluctuations " on a Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) background defined by suitable averages of covariant scalars. We examine the properties of these fluctuations, which can be defined for a confined comoving domain or for an asymptotic domain extending to whole time slices. In particular, the non-local density fluctuation provides a covariant and precise definition for the notion of the "density contrast ". We show that in their linear regime these LTB exact fluctuations (local and non-local) are fully equivalent to the conventional cosmological perturbations in the synchronous-comoving gauge of CPT and to GIC perturbations. As an immediate consequence, we show the time-invariance of the spatial curvature perturbation in a simple form. The present work may provide important theoretical connections between the exact and perturbative (linear or no-linear) approach to the dynamics of dust sources in General Relativity. |
gr-qc/0503075 | Luc Blanchet | Luc Blanchet, Guillaume Faye, Samaya Nissanke | On the structure of the post-Newtonian expansion in general relativity | 22 pages, to appear in Phys. Rev. D | Phys.Rev. D72 (2005) 044024 | 10.1103/PhysRevD.72.044024 | null | gr-qc | null | In the continuation of a preceding work, we derive a new expression for the
metric in the near zone of an isolated matter system in post-Newtonian
approximations of general relativity. The post-Newtonian metric, a solution of
the field equations in harmonic coordinates, is formally valid up to any order,
and is cast in the form of a particular solution of the wave equation, plus a
specific homogeneous solution which ensures the asymptotic matching to the
multipolar expansion of the gravitational field in the exterior of the system.
The new form provides some insights on the structure of the post-Newtonian
expansion in general relativity and the gravitational radiation reaction terms
therein.
| [
{
"created": "Thu, 17 Mar 2005 16:40:15 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Jul 2005 15:54:14 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Blanchet",
"Luc",
""
],
[
"Faye",
"Guillaume",
""
],
[
"Nissanke",
"Samaya",
""
]
] | In the continuation of a preceding work, we derive a new expression for the metric in the near zone of an isolated matter system in post-Newtonian approximations of general relativity. The post-Newtonian metric, a solution of the field equations in harmonic coordinates, is formally valid up to any order, and is cast in the form of a particular solution of the wave equation, plus a specific homogeneous solution which ensures the asymptotic matching to the multipolar expansion of the gravitational field in the exterior of the system. The new form provides some insights on the structure of the post-Newtonian expansion in general relativity and the gravitational radiation reaction terms therein. |
2406.00265 | Zhi Luo | Zhi Luo, Jin Li, Ke-Jian He, Hao Yu | Shadows, Quasinormal Modes, and Optical Appearances of Black Holes in
Horndeski Theory | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work describes the motion of photons in black hole (BH) spacetimes
within the framework of Horndeski theory. We focus on the shadows, quasinormal
modes (QNMs) and optical appearances of BHs surrounded by geometrically thin
accretion disks. The QNMs of BHs are calculated by the WKB method and the
eikonal limit, respectively. Using Event Horizon Telescope (EHT) observations
of $\mathrm{M} 87^*$ and $\mathrm{Sgr} \mathrm{A}^*$, we can constrain the
parameter in Horndeski theory to a small range. Based on the constraint, we
obtain the frequency ranges of the fundamental modes for $\mathrm{M} 87^*$ and
$\mathrm{Sgr} \mathrm{A}^*$ in Horndeski theory. By exploring the optical
appearances of BHs, we find that for the current resolution of the EHT, it
primarily captures direct emission. This work advances our understanding of the
observational characteristics of BHs in Horndeski theory and constrains
Horndeski theory by EHT observations of $\mathrm{M} 87^*$ and $\mathrm{Sgr}
\mathrm{A}^*$.
| [
{
"created": "Sat, 1 Jun 2024 02:07:20 GMT",
"version": "v1"
},
{
"created": "Mon, 22 Jul 2024 14:33:30 GMT",
"version": "v2"
}
] | 2024-07-23 | [
[
"Luo",
"Zhi",
""
],
[
"Li",
"Jin",
""
],
[
"He",
"Ke-Jian",
""
],
[
"Yu",
"Hao",
""
]
] | This work describes the motion of photons in black hole (BH) spacetimes within the framework of Horndeski theory. We focus on the shadows, quasinormal modes (QNMs) and optical appearances of BHs surrounded by geometrically thin accretion disks. The QNMs of BHs are calculated by the WKB method and the eikonal limit, respectively. Using Event Horizon Telescope (EHT) observations of $\mathrm{M} 87^*$ and $\mathrm{Sgr} \mathrm{A}^*$, we can constrain the parameter in Horndeski theory to a small range. Based on the constraint, we obtain the frequency ranges of the fundamental modes for $\mathrm{M} 87^*$ and $\mathrm{Sgr} \mathrm{A}^*$ in Horndeski theory. By exploring the optical appearances of BHs, we find that for the current resolution of the EHT, it primarily captures direct emission. This work advances our understanding of the observational characteristics of BHs in Horndeski theory and constrains Horndeski theory by EHT observations of $\mathrm{M} 87^*$ and $\mathrm{Sgr} \mathrm{A}^*$. |
1108.0081 | Donatella Fiorucci | Donatella Fiorucci, Orchidea Maria Lecian and Giovanni Montani | Non-analytical power law correction to the Einstein-Hilbert action:
gravitational wave propagation | 18 pages, 3 figures | null | 10.1142/S0217732314501788 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the features of the Minkowskian limit of a particular
non-analytical f(R) model, whose Taylor expansion in the weak field limit does
not hold, as far as gravitational waves (GWs) are concerned. We solve the
corresponding Einstein equations and we find an explicit expression of the
modified GWs as the sum of two terms, i.e. the standard one and a modified
part. As a result, GWs in this model are not transverse, and their polarization
is different from that of General Relativity. The velocity of the GW modified
part depends crucially on the parameters characterizing the model, and it
mostly results much smaller than the speed of light. Moreover, this
investigation allows one to further test the viability of this particular f(R)
gravity theory as far as interferometric observations of GWs are concerned.
| [
{
"created": "Sat, 30 Jul 2011 15:36:10 GMT",
"version": "v1"
}
] | 2014-10-24 | [
[
"Fiorucci",
"Donatella",
""
],
[
"Lecian",
"Orchidea Maria",
""
],
[
"Montani",
"Giovanni",
""
]
] | We analyze the features of the Minkowskian limit of a particular non-analytical f(R) model, whose Taylor expansion in the weak field limit does not hold, as far as gravitational waves (GWs) are concerned. We solve the corresponding Einstein equations and we find an explicit expression of the modified GWs as the sum of two terms, i.e. the standard one and a modified part. As a result, GWs in this model are not transverse, and their polarization is different from that of General Relativity. The velocity of the GW modified part depends crucially on the parameters characterizing the model, and it mostly results much smaller than the speed of light. Moreover, this investigation allows one to further test the viability of this particular f(R) gravity theory as far as interferometric observations of GWs are concerned. |
gr-qc/0512162 | Danielsson | Ulf H. Danielsson | Quantum gravitational proton decay at high temperature | 3 pages | null | null | null | gr-qc | null | One of the most important challenges of contemporary physics is to find
experimental signatures of quantum gravity. It is expected that quantum
gravitational effects lead to proton decay but on time scales way beyond what
is of any relevance to experiments. At non-zero temperatures there are reasons
to believe that the situation is much more favourable. We will argue that at
the temperatures and densities reached at present and future fusion facilities
there is a realistic possibility that proton decay could be detectable.
| [
{
"created": "Thu, 29 Dec 2005 14:26:31 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Danielsson",
"Ulf H.",
""
]
] | One of the most important challenges of contemporary physics is to find experimental signatures of quantum gravity. It is expected that quantum gravitational effects lead to proton decay but on time scales way beyond what is of any relevance to experiments. At non-zero temperatures there are reasons to believe that the situation is much more favourable. We will argue that at the temperatures and densities reached at present and future fusion facilities there is a realistic possibility that proton decay could be detectable. |
gr-qc/0410018 | Ryuichi Fujita | Ryuichi Fujita and Hideyuki Tagoshi | New Numerical Methods to Evaluate Homogeneous Solutions of the Teukolsky
Equation | 36 pages,7 figures | Prog.Theor.Phys. 112 (2004) 415-450 | 10.1143/PTP.112.415 | null | gr-qc | null | We discuss a numerical method to compute the homogeneous solutions of the
Teukolsky equation which is the basic equation of the black hole perturbation
method. We use the formalism developed by Mano, Suzuki and Takasugi, in which
the homogeneous solutions of the radial Teukolsky equation are expressed in
terms of two kinds of series of special functions, and the formulas for the
asymptotic amplitudes are derived explicitly.Although the application of this
method was previously limited to the analytical evaluation of the homogeneous
solutions, we find that it is also useful for numerical computation. We also
find that so-called "renormalized angular momentum parameter", $\nu$, can be
found only in the limited region of $\omega$ for each $l,m$ if we assume $\nu$
is real (here, $\omega$ is the angular frequency, and $l$ and $m$ are degree
and order of the spin-weighted spheroidal harmonics respectively). We also
compute the flux of the gravitational waves induced by a compact star in a
circular orbit on the equatorial plane around a rotating black hole. We find
that the relative error of the energy flux is about $10^{-14}$ which is much
smaller than the one obtained by usual numerical integration methods.
| [
{
"created": "Tue, 5 Oct 2004 09:16:12 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Fujita",
"Ryuichi",
""
],
[
"Tagoshi",
"Hideyuki",
""
]
] | We discuss a numerical method to compute the homogeneous solutions of the Teukolsky equation which is the basic equation of the black hole perturbation method. We use the formalism developed by Mano, Suzuki and Takasugi, in which the homogeneous solutions of the radial Teukolsky equation are expressed in terms of two kinds of series of special functions, and the formulas for the asymptotic amplitudes are derived explicitly.Although the application of this method was previously limited to the analytical evaluation of the homogeneous solutions, we find that it is also useful for numerical computation. We also find that so-called "renormalized angular momentum parameter", $\nu$, can be found only in the limited region of $\omega$ for each $l,m$ if we assume $\nu$ is real (here, $\omega$ is the angular frequency, and $l$ and $m$ are degree and order of the spin-weighted spheroidal harmonics respectively). We also compute the flux of the gravitational waves induced by a compact star in a circular orbit on the equatorial plane around a rotating black hole. We find that the relative error of the energy flux is about $10^{-14}$ which is much smaller than the one obtained by usual numerical integration methods. |
1006.2227 | Ujjal Debnath | Writambhara Chakraborty and Ujjal Debnath | A New Variable Modified Chaplygin Gas Model Interacting with Scalar
Field | 7 pages, 3 figures | Grav.Cosmol.16:223-227,2010 | 10.1134/S0202289310030059 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this letter we present a new form of the well known Chaplygin gas model by
introducing inhomogeneity in the EOS. This model explains $\omega=-1$ crossing.
Also we have given a graphical representation of the model using $\{r,s\}$
parameters. We have also considered an interaction of this model with the
scalar field by introducing a phenomenological coupling function and have shown
that the potential decays with time.
| [
{
"created": "Fri, 11 Jun 2010 08:21:48 GMT",
"version": "v1"
}
] | 2014-11-21 | [
[
"Chakraborty",
"Writambhara",
""
],
[
"Debnath",
"Ujjal",
""
]
] | In this letter we present a new form of the well known Chaplygin gas model by introducing inhomogeneity in the EOS. This model explains $\omega=-1$ crossing. Also we have given a graphical representation of the model using $\{r,s\}$ parameters. We have also considered an interaction of this model with the scalar field by introducing a phenomenological coupling function and have shown that the potential decays with time. |
2307.06999 | Piero Rettegno | Piero Rettegno, Geraint Pratten, Lucy Thomas, Patricia Schmidt,
Thibault Damour | Strong-field scattering of two spinning black holes: Numerical
Relativity versus post-Minkowskian gravity | 23 pages, 12 figures, 6 tables, 1 ancillary file | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Highly accurate models of the gravitational-wave signal from coalescing
compact binaries are built by completing analytical computations of the binary
dynamics with non-perturbative information from numerical relativity (NR)
simulations. In this paper we present four sets of NR simulations of equal-mass
black hole binaries that undergo strong-field scattering: (i) we reproduce and
extend the nonspinning simulations first presented in [Damour \textit{et al.},
Phys.Rev.D 89 (2014) 8, 081503], (ii) we compute two suites of nonspinning
simulations at higher energies, probing stronger field interactions, (iii) we
present a series of \textit{spinning} simulations including, for the first
time, unequal-spin configurations. When comparing the NR scattering angles to
analytical predictions based on state-of-the-art post-Minkowskian (PM)
calculations, we find that PM-expanded scattering angles show poor convergence
towards NR data. By contrast, a resummed computation of scattering angles via a
spin-dependent, radiation-reacted, effective-one-body potential shows excellent
agreement for both nonspinning and spinning configurations.
| [
{
"created": "Thu, 13 Jul 2023 18:01:06 GMT",
"version": "v1"
},
{
"created": "Sun, 19 Nov 2023 20:47:26 GMT",
"version": "v2"
}
] | 2023-11-21 | [
[
"Rettegno",
"Piero",
""
],
[
"Pratten",
"Geraint",
""
],
[
"Thomas",
"Lucy",
""
],
[
"Schmidt",
"Patricia",
""
],
[
"Damour",
"Thibault",
""
]
] | Highly accurate models of the gravitational-wave signal from coalescing compact binaries are built by completing analytical computations of the binary dynamics with non-perturbative information from numerical relativity (NR) simulations. In this paper we present four sets of NR simulations of equal-mass black hole binaries that undergo strong-field scattering: (i) we reproduce and extend the nonspinning simulations first presented in [Damour \textit{et al.}, Phys.Rev.D 89 (2014) 8, 081503], (ii) we compute two suites of nonspinning simulations at higher energies, probing stronger field interactions, (iii) we present a series of \textit{spinning} simulations including, for the first time, unequal-spin configurations. When comparing the NR scattering angles to analytical predictions based on state-of-the-art post-Minkowskian (PM) calculations, we find that PM-expanded scattering angles show poor convergence towards NR data. By contrast, a resummed computation of scattering angles via a spin-dependent, radiation-reacted, effective-one-body potential shows excellent agreement for both nonspinning and spinning configurations. |
1006.0138 | Luigi Ferraioli | Luigi Ferraioli, Gerhard Heinzel, Martin Hewitson, Mauro Hueller,
Anneke Monsky, Miquel Nofrarias and Stefano Vitale | Calibrating spectral estimation for the LISA Technology Package with
multichannel synthetic noise generation | Accepted for publication in Physical Review D (http://prd.aps.org/) | Phys.Rev.D82:042001,2010 | 10.1103/PhysRevD.82.042001 | null | gr-qc physics.data-an | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The scientific objectives of the Lisa Technology Package (LTP) experiment, on
board of the LISA Pathfinder mission, demand for an accurate calibration and
validation of the data analysis tools in advance of the mission launch. The
levels of confidence required on the mission outcomes can be reached only with
an intense activity on synthetically generated data. A flexible procedure
allowing the generation of cross-correlated stationary noise time series was
set-up. Multi-channel time series with the desired cross correlation behavior
can be generated once a model for a multichannel cross-spectral matrix is
provided. The core of the procedure is the synthesis of a noise coloring
multichannel filter through a frequency-by-frequency eigendecomposition of the
model cross-spectral matrix and a Z-domain fit. The common problem of initial
transients in noise time series is solved with a proper initialization of the
filter recursive equations. The noise generator performances were tested in a
two dimensional case study of the LTP dynamics along the two principal channels
of the sensing interferometer.
| [
{
"created": "Tue, 1 Jun 2010 14:20:08 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Jun 2010 13:39:19 GMT",
"version": "v2"
},
{
"created": "Fri, 11 Jun 2010 15:54:03 GMT",
"version": "v3"
},
{
"created": "Thu, 15 Jul 2010 13:31:52 GMT",
"version": "v4"
}
] | 2014-11-21 | [
[
"Ferraioli",
"Luigi",
""
],
[
"Heinzel",
"Gerhard",
""
],
[
"Hewitson",
"Martin",
""
],
[
"Hueller",
"Mauro",
""
],
[
"Monsky",
"Anneke",
""
],
[
"Nofrarias",
"Miquel",
""
],
[
"Vitale",
"Stefano",
""
]
] | The scientific objectives of the Lisa Technology Package (LTP) experiment, on board of the LISA Pathfinder mission, demand for an accurate calibration and validation of the data analysis tools in advance of the mission launch. The levels of confidence required on the mission outcomes can be reached only with an intense activity on synthetically generated data. A flexible procedure allowing the generation of cross-correlated stationary noise time series was set-up. Multi-channel time series with the desired cross correlation behavior can be generated once a model for a multichannel cross-spectral matrix is provided. The core of the procedure is the synthesis of a noise coloring multichannel filter through a frequency-by-frequency eigendecomposition of the model cross-spectral matrix and a Z-domain fit. The common problem of initial transients in noise time series is solved with a proper initialization of the filter recursive equations. The noise generator performances were tested in a two dimensional case study of the LTP dynamics along the two principal channels of the sensing interferometer. |
2304.04281 | Tommaso Favalli | Tommaso Favalli and Augusto Smerzi | Time dilation of quantum clocks in a Newtonian gravitational field | 8 pages, 2 figures | null | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | We consider two non-relativistic quantum clocks interacting with a Newtonian
gravitational field produced by a spherical mass. In the framework of Page and
Wootters approach, we derive a time dilation for the time states of the clocks.
The delay is in agreement up to first order with the gravitational time
dilation obtained from the Schwarzschild metric. This result can be extended by
considering the relativistic gravitational potential: in this case we obtain
the agreement with the exact Schwarzschild solution.
| [
{
"created": "Sun, 9 Apr 2023 17:02:51 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Sep 2023 10:42:01 GMT",
"version": "v2"
},
{
"created": "Sun, 26 Nov 2023 04:54:35 GMT",
"version": "v3"
},
{
"created": "Wed, 1 May 2024 19:46:34 GMT",
"version": "v4"
}
] | 2024-05-03 | [
[
"Favalli",
"Tommaso",
""
],
[
"Smerzi",
"Augusto",
""
]
] | We consider two non-relativistic quantum clocks interacting with a Newtonian gravitational field produced by a spherical mass. In the framework of Page and Wootters approach, we derive a time dilation for the time states of the clocks. The delay is in agreement up to first order with the gravitational time dilation obtained from the Schwarzschild metric. This result can be extended by considering the relativistic gravitational potential: in this case we obtain the agreement with the exact Schwarzschild solution. |
0712.3742 | Burkhard Kleihaus | Burkhard Kleihaus, Jutta Kunz, Meike List, Isabell Schaffer | Rotating Boson Stars and Q-Balls II: Negative Parity and Ergoregions | 20 pages, 17 figures | Phys.Rev.D77:064025,2008 | 10.1103/PhysRevD.77.064025 | null | gr-qc | null | We construct axially symmetric, rotating boson stars with positive and
negative parity. Their flat space limits represent spinning Q-balls. $Q$-balls
and boson stars exist only in a limited frequency range. The coupling to
gravity gives rise to a spiral-like frequency dependence of the mass and charge
of boson stars. We analyze the properties of these solutions. In particular, we
discuss the presence of ergoregions in boson stars, and determine their domains
of existence.
| [
{
"created": "Fri, 21 Dec 2007 16:28:56 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
],
[
"List",
"Meike",
""
],
[
"Schaffer",
"Isabell",
""
]
] | We construct axially symmetric, rotating boson stars with positive and negative parity. Their flat space limits represent spinning Q-balls. $Q$-balls and boson stars exist only in a limited frequency range. The coupling to gravity gives rise to a spiral-like frequency dependence of the mass and charge of boson stars. We analyze the properties of these solutions. In particular, we discuss the presence of ergoregions in boson stars, and determine their domains of existence. |
1205.1168 | Burin Gumjudpai | Antonio De Felice (IF, Naresuan), Burin Gumjudpai (IF, Naresuan),
Sanjay Jhingan (CTP, Jamia Millia Islamia) | Cosmological constraints for an Eddington-Born-Infeld field | 8 pages, 4 figures | Physical Review D 86, 043525 (2012) | 10.1103/PhysRevD.86.043525 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the Eddington-Born-Infeld (EBI) model here without assuming any
cosmological constant. The EBI scalar field is supposed to play a role of both
dark matter and dark energy. Different eras in cosmology are reconstructed for
the model. A comparison is drawn with $\Lambda$CDM model using Supernova Ia,
WMAP7 and BAO data. It seems that the EBI field in this form does not give good
fit to observational data in comparison to the $\Lambda$CDM model.
| [
{
"created": "Sun, 6 May 2012 00:58:08 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Aug 2012 10:03:11 GMT",
"version": "v2"
}
] | 2012-08-28 | [
[
"De Felice",
"Antonio",
"",
"IF, Naresuan"
],
[
"Gumjudpai",
"Burin",
"",
"IF, Naresuan"
],
[
"Jhingan",
"Sanjay",
"",
"CTP, Jamia Millia Islamia"
]
] | We consider the Eddington-Born-Infeld (EBI) model here without assuming any cosmological constant. The EBI scalar field is supposed to play a role of both dark matter and dark energy. Different eras in cosmology are reconstructed for the model. A comparison is drawn with $\Lambda$CDM model using Supernova Ia, WMAP7 and BAO data. It seems that the EBI field in this form does not give good fit to observational data in comparison to the $\Lambda$CDM model. |
1709.02133 | Mohammad Sami | Abhineet Agarwal, R. Myrzakulov, S. K. J. Pacif, M. Sami, Anzhong Wang | Cosmic acceleration sourced by modification of gravity without extra
degrees of freedom | 17 pages, 2 tables and 5 figures; minor clarifications added, to
appear in IJGMMP | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate a scenario in which late time cosmic
acceleration might arise due to coupling between dark matter and baryonic
matter without resorting to dark energy or large scale modification of gravity
associated with extra degrees of freedom. The scenario can give rise to late
time acceleration in Jordan frame and no acceleration in Einstein frame -
\textit{generic modification of gravity} caused by disformal coupling. Using a
simple parametrization of the coupling function, in maximally disformal case,
we constrain the model parameters by using the age constraints due to globular
cluster data. We also obtain observational constraints on the parameters using
$H(z)+SNIa+BAO$ data sets. In this case, we distinguish between phantom and non
phantom acceleration and show that the model can give rise to phantom behavior
in a narrow region of parameter space.
| [
{
"created": "Thu, 7 Sep 2017 08:26:34 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Jun 2019 07:55:13 GMT",
"version": "v2"
}
] | 2019-06-18 | [
[
"Agarwal",
"Abhineet",
""
],
[
"Myrzakulov",
"R.",
""
],
[
"Pacif",
"S. K. J.",
""
],
[
"Sami",
"M.",
""
],
[
"Wang",
"Anzhong",
""
]
] | In this paper, we investigate a scenario in which late time cosmic acceleration might arise due to coupling between dark matter and baryonic matter without resorting to dark energy or large scale modification of gravity associated with extra degrees of freedom. The scenario can give rise to late time acceleration in Jordan frame and no acceleration in Einstein frame - \textit{generic modification of gravity} caused by disformal coupling. Using a simple parametrization of the coupling function, in maximally disformal case, we constrain the model parameters by using the age constraints due to globular cluster data. We also obtain observational constraints on the parameters using $H(z)+SNIa+BAO$ data sets. In this case, we distinguish between phantom and non phantom acceleration and show that the model can give rise to phantom behavior in a narrow region of parameter space. |
gr-qc/0703054 | Matyas Vasuth | M\'aty\'as Vas\'uth, Bal\'azs Mik\'oczi, L\'aszl\'o \'A. Gergely | Orbital phase in inspiralling compact binaries | to appear in the Proceedings of the Eleventh Marcel Grossmann Meeting
2006, World Scientific, Singapore (2007) | null | 10.1142/9789812834300_0443 | null | gr-qc | null | We derive the rate of change of the mean motion up to the second
post-Newtonian order for inspiralling compact binaries with spin, mass
quadrupole and magnetic dipole moments on eccentric orbits. We give this result
in terms of orbital elements. We also present the related orbital phase for
circular orbits.
| [
{
"created": "Thu, 8 Mar 2007 14:14:26 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Mar 2007 21:36:44 GMT",
"version": "v2"
}
] | 2016-11-15 | [
[
"Vasúth",
"Mátyás",
""
],
[
"Mikóczi",
"Balázs",
""
],
[
"Gergely",
"László Á.",
""
]
] | We derive the rate of change of the mean motion up to the second post-Newtonian order for inspiralling compact binaries with spin, mass quadrupole and magnetic dipole moments on eccentric orbits. We give this result in terms of orbital elements. We also present the related orbital phase for circular orbits. |
1303.6620 | Lorenzo Luis Salcedo | C. Garcia-Recio and L. L. Salcedo | The perturbative scalar massless propagator in Schwarzschild spacetime | 6 pages, 1 figuere | Class. Quantum Grav. 30 (2013) 097001 | 10.1088/0264-9381/30/9/097001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A short derivation is given of the weak gravitational field approximation to
the scalar massless propagator in Schwarzschild spacetime obtained by Paszko
using the path-integral approach. The contribution from the direct coupling of
the quantum field to the scalar curvature is explictly included. The propagator
complies with Hadamard's pattern, and the vacuum state is consistent with the
perturbative version of the Boulware vacuum. The momentum space propagator is
computed for massless or massive particles to the same perturbative order. The
renormalized value of $\ < \phi^2(x)\ >$ for the massless case is reproduced.
| [
{
"created": "Tue, 26 Mar 2013 19:48:33 GMT",
"version": "v1"
}
] | 2013-04-22 | [
[
"Garcia-Recio",
"C.",
""
],
[
"Salcedo",
"L. L.",
""
]
] | A short derivation is given of the weak gravitational field approximation to the scalar massless propagator in Schwarzschild spacetime obtained by Paszko using the path-integral approach. The contribution from the direct coupling of the quantum field to the scalar curvature is explictly included. The propagator complies with Hadamard's pattern, and the vacuum state is consistent with the perturbative version of the Boulware vacuum. The momentum space propagator is computed for massless or massive particles to the same perturbative order. The renormalized value of $\ < \phi^2(x)\ >$ for the massless case is reproduced. |
2304.12823 | Adam Cie\'slik | Adam Cie\'slik, Patryk Mach | Timelike and null geodesics in the Schwarzschild space-time: Analytical
solutions | 10 pages, 0 figures | Acta Phys. Pol. B Proc. Suppl. 16, 6-A10 (2023) | 10.5506/APhysPolBSupp.16.6-A10 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The theory of Schwarzschild geodesics is revisited. Using a theorem due to
Weierstrass and Biermann, we derive concise formulas describing all timelike
and null trajectories in terms of Weierstrass elliptic functions. The
formulation given in this note uses an analogue of the so-called Mino time.
| [
{
"created": "Tue, 25 Apr 2023 13:50:10 GMT",
"version": "v1"
}
] | 2023-06-27 | [
[
"Cieślik",
"Adam",
""
],
[
"Mach",
"Patryk",
""
]
] | The theory of Schwarzschild geodesics is revisited. Using a theorem due to Weierstrass and Biermann, we derive concise formulas describing all timelike and null trajectories in terms of Weierstrass elliptic functions. The formulation given in this note uses an analogue of the so-called Mino time. |
1803.03283 | Gabriela B\'arcenas-Enr\'iquez | Gabriela B\'arcenas-Enr\'iquez, Celia Escamilla-Rivera and Miguel A.
Garcia-Aspeitia | Cosmological analysis of a DGP stable model with $H(z)$ observations a
revision | 6 pages, 3 figures, accepted for publication in RMF | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we will present a Dvali-Gabadadze-Porrati stable model in
order to perform an observational test using $H(z)$ data and radial BAO scale
in the galaxy distribution. In this vein, we study the tension between
constraints on the cosmological constant $\Lambda$ and the crossover scale
$r_c$, which is associated with the DGP model. Our results show that
observations do not favor the DGP stable model as a possible candidate to fit
the observations of the late cosmic acceleration.
| [
{
"created": "Thu, 8 Mar 2018 19:24:32 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Jun 2018 22:08:33 GMT",
"version": "v2"
}
] | 2018-06-29 | [
[
"Bárcenas-Enríquez",
"Gabriela",
""
],
[
"Escamilla-Rivera",
"Celia",
""
],
[
"Garcia-Aspeitia",
"Miguel A.",
""
]
] | In this paper, we will present a Dvali-Gabadadze-Porrati stable model in order to perform an observational test using $H(z)$ data and radial BAO scale in the galaxy distribution. In this vein, we study the tension between constraints on the cosmological constant $\Lambda$ and the crossover scale $r_c$, which is associated with the DGP model. Our results show that observations do not favor the DGP stable model as a possible candidate to fit the observations of the late cosmic acceleration. |
2005.06237 | Alexander Zhuk | Alvina Burgazli, Valerii Shulga, A.Emrah Y\"ukselci, Alexander Zhuk | Effect of peculiar velocities on the gravitational potential in
cosmological models with perfect fluids | 7 pages, 4 figures, references added, matches published version | Physics Letters B 809 (2020) 135761 | 10.1016/j.physletb.2020.135761 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a universe filled with perfect fluid with the constant equation
of state parameter $\omega$. In the theory of scalar perturbations, we study
the effect of peculiar velocities on the gravitational potential. For radiation
with $\omega=1/3$, we obtain the expression for the gravitational potential in
the integral form. Numerical calculation clearly demonstrates the modulation of
the gravitational potential by acoustic oscillations due to the presence of
peculiar velocities. We also show that peculiar velocities affect the
gravitational potential in the case of the frustrated network of cosmic strings
with $\omega =-1/3$.
| [
{
"created": "Wed, 13 May 2020 10:21:18 GMT",
"version": "v1"
},
{
"created": "Fri, 18 Sep 2020 16:10:52 GMT",
"version": "v2"
}
] | 2020-09-21 | [
[
"Burgazli",
"Alvina",
""
],
[
"Shulga",
"Valerii",
""
],
[
"Yükselci",
"A. Emrah",
""
],
[
"Zhuk",
"Alexander",
""
]
] | We consider a universe filled with perfect fluid with the constant equation of state parameter $\omega$. In the theory of scalar perturbations, we study the effect of peculiar velocities on the gravitational potential. For radiation with $\omega=1/3$, we obtain the expression for the gravitational potential in the integral form. Numerical calculation clearly demonstrates the modulation of the gravitational potential by acoustic oscillations due to the presence of peculiar velocities. We also show that peculiar velocities affect the gravitational potential in the case of the frustrated network of cosmic strings with $\omega =-1/3$. |
2307.09107 | Arick Shao | Arick Shao | Bulk-boundary correspondences and unique continuation in asymptotically
Anti-de Sitter spacetimes | To be published in "MATRIX Annals" | null | null | null | gr-qc hep-th math.AP math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article surveys the research presented by the author at the MATRIX
Institute workshop "Hyperbolic Differential Equations in Geometry and Physics"
in April 2022. The work is centered about establishing rigorous mathematical
statements toward the AdS/CFT correspondence in theoretical physics, in
particular in dynamical settings. The contents are mainly based on the recent
paper with G. Holzegel that proved a unique continuation result for the
Einstein-vacuum equations from asymptotically Anti-de Sitter (aAdS) conformal
boundaries. We also discuss some preceding results, in particular novel
Carleman estimates for wave equations on aAdS spacetimes, which laid the
foundations toward the main correspondence theorems.
| [
{
"created": "Tue, 18 Jul 2023 09:56:51 GMT",
"version": "v1"
}
] | 2023-07-19 | [
[
"Shao",
"Arick",
""
]
] | This article surveys the research presented by the author at the MATRIX Institute workshop "Hyperbolic Differential Equations in Geometry and Physics" in April 2022. The work is centered about establishing rigorous mathematical statements toward the AdS/CFT correspondence in theoretical physics, in particular in dynamical settings. The contents are mainly based on the recent paper with G. Holzegel that proved a unique continuation result for the Einstein-vacuum equations from asymptotically Anti-de Sitter (aAdS) conformal boundaries. We also discuss some preceding results, in particular novel Carleman estimates for wave equations on aAdS spacetimes, which laid the foundations toward the main correspondence theorems. |
1808.09765 | Andreas G. A. Pithis | Andreas G. A. Pithis and Johannes Th\"urigen | Phase transitions in group field theory: The Landau perspective | 17 pages, matches published version | Phys. Rev. D 98, 126006 (2018) | 10.1103/PhysRevD.98.126006 | KCL-PH-TH/2018-39 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In various approaches to quantum gravity continuum spacetime is expected to
emerge from discrete geometries through a phase transition. In group field
theory, various indications for such a transition have recently been found but
a complete understanding of such a phenomenon remains an open issue. In this
work, we investigate the critical behavior of different group field theory
models in the Gaussian approximation. Applying the Ginzburg criterion to
quantify field fluctuations, we find that this approximation breaks down in the
case of three-dimensional Euclidean quantum gravity as described by the
dynamical Boulatov model on the compact group $\text{SU}(2)$. This result is
independent of the peculiar gauge symmetry and specific form of nonlocality of
the model. On the contrary, we find that the Gaussian approximation is valid
for a rank-$1$ GFT on the noncompact sector of fields on
$\text{SL}(2,\mathbb{R})$ related to Lorentzian models. Though a
nonperturbative analysis is needed to settle the question of phase transitions
for compact groups, the results may also indicate the necessity to consider
group field theory on noncompact domains for phase transitions to occur.
| [
{
"created": "Wed, 29 Aug 2018 12:40:57 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Dec 2018 17:59:57 GMT",
"version": "v2"
}
] | 2018-12-14 | [
[
"Pithis",
"Andreas G. A.",
""
],
[
"Thürigen",
"Johannes",
""
]
] | In various approaches to quantum gravity continuum spacetime is expected to emerge from discrete geometries through a phase transition. In group field theory, various indications for such a transition have recently been found but a complete understanding of such a phenomenon remains an open issue. In this work, we investigate the critical behavior of different group field theory models in the Gaussian approximation. Applying the Ginzburg criterion to quantify field fluctuations, we find that this approximation breaks down in the case of three-dimensional Euclidean quantum gravity as described by the dynamical Boulatov model on the compact group $\text{SU}(2)$. This result is independent of the peculiar gauge symmetry and specific form of nonlocality of the model. On the contrary, we find that the Gaussian approximation is valid for a rank-$1$ GFT on the noncompact sector of fields on $\text{SL}(2,\mathbb{R})$ related to Lorentzian models. Though a nonperturbative analysis is needed to settle the question of phase transitions for compact groups, the results may also indicate the necessity to consider group field theory on noncompact domains for phase transitions to occur. |
2007.11023 | Mustapha Azreg-A\"inou | Mustapha Azreg-A\"inou | Dynamical and static solutions to $R=0$-scalar-tensor theory | 7 twocolumn pages | EPL, vol. 130 (2020) 60003 | 10.1209/0295-5075/130/60003 | null | gr-qc astro-ph.CO math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the most cosmologically interesting and relevant case of
scalar-tensor theory (STT) and derive new normal and phantom, dynamical and
static, solutions. We determine the Bianchi I Kasner exponents and show that
the dynamical solutions are heteroclinic orbits connecting two singularities.
Approaching the singularities, a purely transverse expansion (no radial
expansion or collapse) may occur.
| [
{
"created": "Tue, 21 Jul 2020 18:15:24 GMT",
"version": "v1"
}
] | 2020-07-23 | [
[
"Azreg-Aïnou",
"Mustapha",
""
]
] | We consider the most cosmologically interesting and relevant case of scalar-tensor theory (STT) and derive new normal and phantom, dynamical and static, solutions. We determine the Bianchi I Kasner exponents and show that the dynamical solutions are heteroclinic orbits connecting two singularities. Approaching the singularities, a purely transverse expansion (no radial expansion or collapse) may occur. |
1906.08835 | Flavio Mercati | Flavio Mercati | Through the Big Bang in inflationary cosmology | 23 pages + 2-page appendix, 9 figures | null | 10.1088/1475-7516/2019/10/025 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Singularities in General Relativity are regions where the description of
spacetime in terms of a pseudo-Riemannian geometry breaks down. The theory
seems unable to predict the evolution of the physical degrees of freedom around
and beyond such regions. In a recent paper, the author and collaborators
challenged this view by providing an example of a singularity at which
Einstein's equations can be rewritten in a form that satisfies an existence and
uniqueness theorem, thereby predicting that each solution can be continued
uniquely through the singularity. This result was obtained under the assumption
of homogeneity (but not isotropy), and requires the presence of a massless free
scalar field. This paper extends the result to N scalar fields with a
potential, the only requirement being that it does not grow too fast. In
particular, the result is compatible with inflationary potentials, e.g.
Starobinsky's. This brings us one step closer to the goal of extending the
original result to realistic cosmologies.
| [
{
"created": "Thu, 20 Jun 2019 20:30:42 GMT",
"version": "v1"
}
] | 2019-10-16 | [
[
"Mercati",
"Flavio",
""
]
] | Singularities in General Relativity are regions where the description of spacetime in terms of a pseudo-Riemannian geometry breaks down. The theory seems unable to predict the evolution of the physical degrees of freedom around and beyond such regions. In a recent paper, the author and collaborators challenged this view by providing an example of a singularity at which Einstein's equations can be rewritten in a form that satisfies an existence and uniqueness theorem, thereby predicting that each solution can be continued uniquely through the singularity. This result was obtained under the assumption of homogeneity (but not isotropy), and requires the presence of a massless free scalar field. This paper extends the result to N scalar fields with a potential, the only requirement being that it does not grow too fast. In particular, the result is compatible with inflationary potentials, e.g. Starobinsky's. This brings us one step closer to the goal of extending the original result to realistic cosmologies. |
1206.6306 | Jan {\AA}man | Jan E. Aman, Ingemar Bengtsson and Helgi F. Runarsson | What are extremal Kerr Killing vectors up to? | 12 pages, 3 figures | Class. Quantum Grav. 29 215017 (2012) | 10.1088/0264-9381/29/21/215017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the extremal Kerr spacetime the horizon Killing vector field is null on a
timelike hypersurface crossing the horizon at a fixed latitude, and spacelike
on both sides of the horizon in the equatorial plane. We explain in some detail
how this behaviour is consistent with the existence of timelike Killing vectors
everywhere off the horizon, and how it arises in a limit from the Kerr
spacetime where there is a similar hypersurface strictly outside the horizon.
| [
{
"created": "Wed, 27 Jun 2012 15:22:28 GMT",
"version": "v1"
}
] | 2013-03-20 | [
[
"Aman",
"Jan E.",
""
],
[
"Bengtsson",
"Ingemar",
""
],
[
"Runarsson",
"Helgi F.",
""
]
] | In the extremal Kerr spacetime the horizon Killing vector field is null on a timelike hypersurface crossing the horizon at a fixed latitude, and spacelike on both sides of the horizon in the equatorial plane. We explain in some detail how this behaviour is consistent with the existence of timelike Killing vectors everywhere off the horizon, and how it arises in a limit from the Kerr spacetime where there is a similar hypersurface strictly outside the horizon. |
1908.00875 | Francesco Marino | Francesco Marino | Massive phonons and gravitational dynamics in a photon-fluid model | Revised version: a few typos in formulas corrected | Phys. Rev. A 100, 063825 (2019) | 10.1103/PhysRevA.100.063825 | null | gr-qc physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We theoretically investigate the excitation dynamics in a photon-fluid with
both local and nonlocal interactions. We show that the interplay between
locality and an infinite-range nonlocality gives rise to a gapped Bogoliubov
spectrum of elementary excitations which, at lower momenta, correspond to
massive particles (phonons) with a relativistic energy-momentum relation. In
this regime and in the presence of an inhomogeneous flow the density
fluctuations are governed by the massive Klein-Gordon equation on the acoustic
metric and thus propagate as massive scalar fields on a curved spacetime. We
finally demonstrate that in the non-relativistic limit the phonon modes behave
as self-gravitating quantum particles with an effective Schr\"{o}dinger-Newton
dynamics, although with a finite-range gravitational interaction and a non-zero
cosmological constant. Our photon-fluid represents a viable alternative to BEC
models for "emergent-gravity" scenarios and offers a promising setting for
analogue simulations of quantum gravity phenomenology and semiclassical
gravity.
| [
{
"created": "Fri, 2 Aug 2019 14:19:32 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Nov 2019 22:53:11 GMT",
"version": "v2"
},
{
"created": "Tue, 9 Feb 2021 13:00:15 GMT",
"version": "v3"
}
] | 2021-02-10 | [
[
"Marino",
"Francesco",
""
]
] | We theoretically investigate the excitation dynamics in a photon-fluid with both local and nonlocal interactions. We show that the interplay between locality and an infinite-range nonlocality gives rise to a gapped Bogoliubov spectrum of elementary excitations which, at lower momenta, correspond to massive particles (phonons) with a relativistic energy-momentum relation. In this regime and in the presence of an inhomogeneous flow the density fluctuations are governed by the massive Klein-Gordon equation on the acoustic metric and thus propagate as massive scalar fields on a curved spacetime. We finally demonstrate that in the non-relativistic limit the phonon modes behave as self-gravitating quantum particles with an effective Schr\"{o}dinger-Newton dynamics, although with a finite-range gravitational interaction and a non-zero cosmological constant. Our photon-fluid represents a viable alternative to BEC models for "emergent-gravity" scenarios and offers a promising setting for analogue simulations of quantum gravity phenomenology and semiclassical gravity. |
2310.15018 | Francisco Lobo | Ricardo A. C. Cipriano, Tiberiu Harko, Francisco S. N. Lobo, Miguel A.
S. Pinto, Jo\~ao Lu\'is Rosa | Gravitationally induced matter creation in scalar-tensor
$f(R,T_{\mu\nu}T^{\mu\nu})$ gravity | 17 pages; 6 figures. V2: minor corrections; references added. V3: 20
pages, discussion and references added; matches published version | Physics of the Dark Universe 44 (2024) 101463 | 10.1016/j.dark.2024.101463 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we analyze the possibility of gravitationally induced matter
creation in the so-called Energy-Momentum-Squared gravity (EMSG), i.e.
$f(R,T_{\mu\nu}T^{\mu\nu})$ gravity, in its dynamically equivalent
scalar-tensor representation. Given the explicit nonminimal coupling between
matter and geometry in this theory, the energy-momentum tensor is not generally
covariantly conserved, which motivates the study of cosmological scenarios by
resorting to the formalism of irreversible thermodynamics of open systems. We
start by deriving the universe matter creation rates and subsequent
thermodynamical properties, such as, the creation pressure, temperature
evolution, and entropy evolution, in the framework of
$f(R,T_{\mu\nu}T^{\mu\nu})$ gravity. These quantities are then analyzed for a
Friedmann-Lema\^itre-Robertson-Walker (FLRW) background with a scale factor
described by the de Sitter solution, under different assumptions for the mater
distribution, namely a vacuum universe, a constant density universe, and a
time-varying density universe. Finally, we explore cosmological solutions with
varying Hubble parameters and provide a comparison with the standard
cosmological model. Our results indicate that the cosmological evolution in the
framework of EMSG are in close agreement with the observational cosmological
data for low redshift.
| [
{
"created": "Mon, 23 Oct 2023 15:13:52 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Oct 2023 15:37:09 GMT",
"version": "v2"
},
{
"created": "Thu, 14 Mar 2024 13:00:58 GMT",
"version": "v3"
}
] | 2024-03-15 | [
[
"Cipriano",
"Ricardo A. C.",
""
],
[
"Harko",
"Tiberiu",
""
],
[
"Lobo",
"Francisco S. N.",
""
],
[
"Pinto",
"Miguel A. S.",
""
],
[
"Rosa",
"João Luís",
""
]
] | In this work, we analyze the possibility of gravitationally induced matter creation in the so-called Energy-Momentum-Squared gravity (EMSG), i.e. $f(R,T_{\mu\nu}T^{\mu\nu})$ gravity, in its dynamically equivalent scalar-tensor representation. Given the explicit nonminimal coupling between matter and geometry in this theory, the energy-momentum tensor is not generally covariantly conserved, which motivates the study of cosmological scenarios by resorting to the formalism of irreversible thermodynamics of open systems. We start by deriving the universe matter creation rates and subsequent thermodynamical properties, such as, the creation pressure, temperature evolution, and entropy evolution, in the framework of $f(R,T_{\mu\nu}T^{\mu\nu})$ gravity. These quantities are then analyzed for a Friedmann-Lema\^itre-Robertson-Walker (FLRW) background with a scale factor described by the de Sitter solution, under different assumptions for the mater distribution, namely a vacuum universe, a constant density universe, and a time-varying density universe. Finally, we explore cosmological solutions with varying Hubble parameters and provide a comparison with the standard cosmological model. Our results indicate that the cosmological evolution in the framework of EMSG are in close agreement with the observational cosmological data for low redshift. |
1409.4648 | Malik Rakhmanov | Malik Rakhmanov | Fermi-normal, optical, and wave-synchronous coordinates for spacetime
with a plane gravitational wave | null | Class. Quantum Grav. 31 (2014) 085006 | 10.1088/0264-9381/31/8/085006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Fermi normal coordinates provide a standardized way to describe the effects
of gravitation from the point of view of an inertial observer. These
coordinates have always been introduced via perturbation expansions and were
usually limited to distances much less than the characteristic length scale set
by the curvature of spacetime. For a plane gravitational wave this scale is
given by its wavelength which defines the domain of validity for these
coordinates known as the long-wavelength regime. The symmetry of this
spacetime, however, allows us to extend Fermi normal coordinates far beyond the
long-wavelength regime. Here we present an explicit construction for this
long-range Fermi normal coordinate system based on the unique solution of the
boundary-value problem for spacelike geodesics. The resulting formulae amount
to summation of the infinite series for Fermi normal coordinates previously
obtained with perturbation expansions. We also consider two closely related
normal coordinate systems: optical coordinates which are built from null
geodesics and wave-synchronous coordinates which are built from spacelike
geodesics locked in phase with the propagating gravitational wave. The
wave-synchronous coordinates yield the exact solution of Peres and Ehlers-Kundt
which is globally defined. In this case, the limitation of the long-wavelength
regime is completely overcome, and the system of wave-synchronous coordinates
becomes valid for arbitrarily large distances. Comparison of the different
coordinate systems is done by considering the motion of an inertial test mass
in the field of a plane gravitational wave.
| [
{
"created": "Tue, 16 Sep 2014 14:09:33 GMT",
"version": "v1"
}
] | 2015-06-22 | [
[
"Rakhmanov",
"Malik",
""
]
] | Fermi normal coordinates provide a standardized way to describe the effects of gravitation from the point of view of an inertial observer. These coordinates have always been introduced via perturbation expansions and were usually limited to distances much less than the characteristic length scale set by the curvature of spacetime. For a plane gravitational wave this scale is given by its wavelength which defines the domain of validity for these coordinates known as the long-wavelength regime. The symmetry of this spacetime, however, allows us to extend Fermi normal coordinates far beyond the long-wavelength regime. Here we present an explicit construction for this long-range Fermi normal coordinate system based on the unique solution of the boundary-value problem for spacelike geodesics. The resulting formulae amount to summation of the infinite series for Fermi normal coordinates previously obtained with perturbation expansions. We also consider two closely related normal coordinate systems: optical coordinates which are built from null geodesics and wave-synchronous coordinates which are built from spacelike geodesics locked in phase with the propagating gravitational wave. The wave-synchronous coordinates yield the exact solution of Peres and Ehlers-Kundt which is globally defined. In this case, the limitation of the long-wavelength regime is completely overcome, and the system of wave-synchronous coordinates becomes valid for arbitrarily large distances. Comparison of the different coordinate systems is done by considering the motion of an inertial test mass in the field of a plane gravitational wave. |
0708.4048 | Yosef Zlochower | Carlos O. Lousto, Yosef Zlochower | Further insight into gravitational recoil | 13 pages, 12 figures, revtex 4 | Phys.Rev.D77:044028,2008 | 10.1103/PhysRevD.77.044028 | null | gr-qc astro-ph | null | We test the accuracy of our recently proposed empirical formula to model the
recoil velocity imparted to the merger remnant of spinning, unequal-mass
black-hole binaries. We study three families of black-hole binary
configurations, all with mass ratio q=3/8 (to maximize the unequal-mass
contribution to the kick) and spins aligned (or counter aligned) with the
orbital angular momentum, two with spin configurations chosen to minimize the
spin-induced tangential and radial accelerations of the trajectories
respectively, and a third family where the trajectories are significantly
altered by spin-orbit coupling. We find good agreement between the measured and
predicted recoil velocities for the first two families, and reasonable
agreement for the third. We also re-examine our original generic binary
configuration that led to the discovery of extremely large spin-driven recoil
velocities and inspired our empirical formula, and find reasonable agreement
between the predicted and measured recoil speeds.
| [
{
"created": "Thu, 30 Aug 2007 18:46:01 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Mar 2008 16:06:38 GMT",
"version": "v2"
},
{
"created": "Thu, 13 Mar 2008 11:08:43 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Lousto",
"Carlos O.",
""
],
[
"Zlochower",
"Yosef",
""
]
] | We test the accuracy of our recently proposed empirical formula to model the recoil velocity imparted to the merger remnant of spinning, unequal-mass black-hole binaries. We study three families of black-hole binary configurations, all with mass ratio q=3/8 (to maximize the unequal-mass contribution to the kick) and spins aligned (or counter aligned) with the orbital angular momentum, two with spin configurations chosen to minimize the spin-induced tangential and radial accelerations of the trajectories respectively, and a third family where the trajectories are significantly altered by spin-orbit coupling. We find good agreement between the measured and predicted recoil velocities for the first two families, and reasonable agreement for the third. We also re-examine our original generic binary configuration that led to the discovery of extremely large spin-driven recoil velocities and inspired our empirical formula, and find reasonable agreement between the predicted and measured recoil speeds. |
2108.12430 | Dylan Rankin | Alec Gunny, Dylan Rankin, Jeffrey Krupa, Muhammed Saleem, Tri Nguyen,
Michael Coughlin, Philip Harris, Erik Katsavounidis, Steven Timm, Burt
Holzman | Hardware-accelerated Inference for Real-Time Gravitational-Wave
Astronomy | 21 pages, 14 figures | null | null | null | gr-qc astro-ph.IM physics.comp-ph physics.data-an physics.ins-det | http://creativecommons.org/licenses/by/4.0/ | The field of transient astronomy has seen a revolution with the first
gravitational-wave detections and the arrival of multi-messenger observations
they enabled. Transformed by the first detection of binary black hole and
binary neutron star mergers, computational demands in gravitational-wave
astronomy are expected to grow by at least a factor of two over the next five
years as the global network of kilometer-scale interferometers are brought to
design sensitivity. With the increase in detector sensitivity, real-time
delivery of gravitational-wave alerts will become increasingly important as an
enabler of multi-messenger followup. In this work, we report a novel
implementation and deployment of deep learning inference for real-time
gravitational-wave data denoising and astrophysical source identification. This
is accomplished using a generic Inference-as-a-Service model that is capable of
adapting to the future needs of gravitational-wave data analysis. Our
implementation allows seamless incorporation of hardware accelerators and also
enables the use of commercial or private (dedicated) as-a-service computing.
Based on our results, we propose a paradigm shift in low-latency and offline
computing in gravitational-wave astronomy. Such a shift can address key
challenges in peak-usage, scalability and reliability, and provide a data
analysis platform particularly optimized for deep learning applications. The
achieved sub-millisecond scale latency will also be relevant for any machine
learning-based real-time control systems that may be invoked in the operation
of near-future and next generation ground-based laser interferometers, as well
as the front-end collection, distribution and processing of data from such
instruments.
| [
{
"created": "Fri, 27 Aug 2021 18:00:00 GMT",
"version": "v1"
}
] | 2021-08-31 | [
[
"Gunny",
"Alec",
""
],
[
"Rankin",
"Dylan",
""
],
[
"Krupa",
"Jeffrey",
""
],
[
"Saleem",
"Muhammed",
""
],
[
"Nguyen",
"Tri",
""
],
[
"Coughlin",
"Michael",
""
],
[
"Harris",
"Philip",
""
],
[
"Kat... | The field of transient astronomy has seen a revolution with the first gravitational-wave detections and the arrival of multi-messenger observations they enabled. Transformed by the first detection of binary black hole and binary neutron star mergers, computational demands in gravitational-wave astronomy are expected to grow by at least a factor of two over the next five years as the global network of kilometer-scale interferometers are brought to design sensitivity. With the increase in detector sensitivity, real-time delivery of gravitational-wave alerts will become increasingly important as an enabler of multi-messenger followup. In this work, we report a novel implementation and deployment of deep learning inference for real-time gravitational-wave data denoising and astrophysical source identification. This is accomplished using a generic Inference-as-a-Service model that is capable of adapting to the future needs of gravitational-wave data analysis. Our implementation allows seamless incorporation of hardware accelerators and also enables the use of commercial or private (dedicated) as-a-service computing. Based on our results, we propose a paradigm shift in low-latency and offline computing in gravitational-wave astronomy. Such a shift can address key challenges in peak-usage, scalability and reliability, and provide a data analysis platform particularly optimized for deep learning applications. The achieved sub-millisecond scale latency will also be relevant for any machine learning-based real-time control systems that may be invoked in the operation of near-future and next generation ground-based laser interferometers, as well as the front-end collection, distribution and processing of data from such instruments. |
2404.08026 | Hamed Hadi | H. Hadi, Amin Rezaei Akbarieh, David F. Mota | Gravitational wave pulse and memory effects for hairy Kiselev black hole
and its analogy with Bondi-Sachs formalism | 18 pages, 30 figures | 2024 Class. Quantum Grav | 10.1088/1361-6382/ad3caf | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The investigation of non-vacuum cosmological backgrounds containing black
holes is greatly enhanced by the Kiselev solution. This solution plays a
crucial role in understanding the properties of the background and its
relationship with the features of the black hole. Consequently, the
gravitational memory effects at large distances from the black hole offer a
valuable means of obtaining information about the surrounding field parameter N
and parameters related to the hair of the hairy Kiselev Black hole. This paper
investigates the gravitational memory effects in the context of the Kiselev
solution through two distinct approaches. At first, the gravitational memory
effect at null infinity is explored by utilizing the Bondi-Sachs formalism by
introducing a gravitational wave (GW) pulse to the solution. The resulting
Bondi mass is then analyzed to gain further insight. Therefore, the Kiselev
solution is being examined to determine the variations in Bondi mass caused by
the pulse of GWs. The study of changes in Bondi mass is motivated by the fact
that it is dynamic and time-dependent, and it measures mass on an
asymptotically null slice or the densities of energy on celestial spheres. In
the second approach, the investigation of displacement and velocity memory
effects is undertaken in relation to the deviation of two neighboring geodesics
and the deviation of their derivative influenced by surrounding field parameter
N and the hair of hairy Kiselev black hole. This analysis is conducted within
the context of a gravitational wave pulse present in the background of a hairy
Kiselev black hole surrounded by a field parameter N.
| [
{
"created": "Thu, 11 Apr 2024 12:48:00 GMT",
"version": "v1"
}
] | 2024-04-15 | [
[
"Hadi",
"H.",
""
],
[
"Akbarieh",
"Amin Rezaei",
""
],
[
"Mota",
"David F.",
""
]
] | The investigation of non-vacuum cosmological backgrounds containing black holes is greatly enhanced by the Kiselev solution. This solution plays a crucial role in understanding the properties of the background and its relationship with the features of the black hole. Consequently, the gravitational memory effects at large distances from the black hole offer a valuable means of obtaining information about the surrounding field parameter N and parameters related to the hair of the hairy Kiselev Black hole. This paper investigates the gravitational memory effects in the context of the Kiselev solution through two distinct approaches. At first, the gravitational memory effect at null infinity is explored by utilizing the Bondi-Sachs formalism by introducing a gravitational wave (GW) pulse to the solution. The resulting Bondi mass is then analyzed to gain further insight. Therefore, the Kiselev solution is being examined to determine the variations in Bondi mass caused by the pulse of GWs. The study of changes in Bondi mass is motivated by the fact that it is dynamic and time-dependent, and it measures mass on an asymptotically null slice or the densities of energy on celestial spheres. In the second approach, the investigation of displacement and velocity memory effects is undertaken in relation to the deviation of two neighboring geodesics and the deviation of their derivative influenced by surrounding field parameter N and the hair of hairy Kiselev black hole. This analysis is conducted within the context of a gravitational wave pulse present in the background of a hairy Kiselev black hole surrounded by a field parameter N. |
1811.07204 | Peter K.F. Kuhfittig | Peter K.F. Kuhfittig | Connecting noncommutative geometry to f(R) modified gravity | 7 pages, no figures | New Horizons in Mathematical Physics, vol. 2, No. 4, pp. 62-66,
2018 | 10.22606/nhmp.2018.24002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown in this note that a noncommutative-geometry background determines
the modified-gravity function $f(R)$ for modeling dark matter.
| [
{
"created": "Sat, 17 Nov 2018 18:17:55 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Feb 2019 19:23:42 GMT",
"version": "v2"
},
{
"created": "Thu, 23 May 2019 14:14:14 GMT",
"version": "v3"
}
] | 2019-05-24 | [
[
"Kuhfittig",
"Peter K. F.",
""
]
] | It is shown in this note that a noncommutative-geometry background determines the modified-gravity function $f(R)$ for modeling dark matter. |
gr-qc/0404056 | Bernd Bruegmann | Marcus Ansorg, Bernd Bruegmann, Wolfgang Tichy | A single-domain spectral method for black hole puncture data | 13 pages, 6 figures; published version with one important change, see
Fig. 4 and the corresponding changes to the text | Phys.Rev.D70:064011,2004 | 10.1103/PhysRevD.70.064011 | CGPG-03/12-3 | gr-qc | null | We calculate puncture initial data corresponding to both single and binary
black hole solutions of the constraint equations by means of a pseudo-spectral
method applied in a single spatial domain. Introducing appropriate coordinates,
these methods exhibit rapid convergence of the conformal factor and lead to
highly accurate solutions. As an application we investigate small mass ratios
of binary black holes and compare these with the corresponding test mass limit
that we obtain through a semi-analytical limiting procedure. In particular, we
compare the binding energy of puncture data in this limit with that of a test
particle in the Schwarzschild spacetime and find that it deviates by 50% from
the Schwarzschild result at the innermost stable circular orbit of
Schwarzschild, if the ADM mass at each puncture is used to define the local
black hole masses.
| [
{
"created": "Tue, 13 Apr 2004 12:03:13 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Sep 2004 14:29:43 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Ansorg",
"Marcus",
""
],
[
"Bruegmann",
"Bernd",
""
],
[
"Tichy",
"Wolfgang",
""
]
] | We calculate puncture initial data corresponding to both single and binary black hole solutions of the constraint equations by means of a pseudo-spectral method applied in a single spatial domain. Introducing appropriate coordinates, these methods exhibit rapid convergence of the conformal factor and lead to highly accurate solutions. As an application we investigate small mass ratios of binary black holes and compare these with the corresponding test mass limit that we obtain through a semi-analytical limiting procedure. In particular, we compare the binding energy of puncture data in this limit with that of a test particle in the Schwarzschild spacetime and find that it deviates by 50% from the Schwarzschild result at the innermost stable circular orbit of Schwarzschild, if the ADM mass at each puncture is used to define the local black hole masses. |
0802.3180 | Daniel Gomez Vergel | Daniel G\'omez Vergel | Schrodinger quantization of linearly polarized Gowdy $S^1\times S^2$ and
$S^3$ models coupled to massless scalar fields | 18 pages. Final version to appear in Classical and Quantum Gravity | Class.Quant.Grav.25:175016,2008 | 10.1088/0264-9381/25/17/175016 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we will construct the Schrodinger representation for the
linearly polarized Gowdy $S^1\times S^2$ and $S^3$ models coupled to massless
scalar fields. Here the quantum states belong to a $L^2$-space for a suitable
quantum configuration space endowed with a Gaussian measure, whose support is
analyzed. This study completes the quantization of these systems previously
performed in the Fock scheme, and provides a specially useful framework to
address physically relevant questions.
| [
{
"created": "Thu, 21 Feb 2008 18:01:02 GMT",
"version": "v1"
},
{
"created": "Tue, 27 May 2008 14:27:46 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Jul 2008 12:53:35 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Vergel",
"Daniel Gómez",
""
]
] | In this paper we will construct the Schrodinger representation for the linearly polarized Gowdy $S^1\times S^2$ and $S^3$ models coupled to massless scalar fields. Here the quantum states belong to a $L^2$-space for a suitable quantum configuration space endowed with a Gaussian measure, whose support is analyzed. This study completes the quantization of these systems previously performed in the Fock scheme, and provides a specially useful framework to address physically relevant questions. |
0806.4059 | Tushar Kanti Dey | Tushar Kanti Dey and Surajit Sen | Gravitational lensing by wormholes | 13 pages, 6 figures | Mod.Phys.Lett.A23:953-962,2008 | 10.1142/S0217732308025498 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have investigated the gravitational lensing by two wormholes, viz.,
Janis-Newman-Winnicour (JNW) wormhole and Ellis wormhole. The deflection angle
in the strong field limit is calculated and various lens parameters of two
wormholes are compared. It is shown that the JNW wormhole exhibits the
relativistic images, while the Ellis wormhole does not have any relativistic
images due to the absence of its photon sphere.
| [
{
"created": "Wed, 25 Jun 2008 09:48:17 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Dey",
"Tushar Kanti",
""
],
[
"Sen",
"Surajit",
""
]
] | We have investigated the gravitational lensing by two wormholes, viz., Janis-Newman-Winnicour (JNW) wormhole and Ellis wormhole. The deflection angle in the strong field limit is calculated and various lens parameters of two wormholes are compared. It is shown that the JNW wormhole exhibits the relativistic images, while the Ellis wormhole does not have any relativistic images due to the absence of its photon sphere. |
1912.11451 | Yury F. Pirogov | Yury F. Pirogov | Quartet-metric gravity, scalar-graviton dark substance and vacuum energy
screening: extending GR vs. its WTDiff alternative | 18 pages | null | null | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the frameworks of the effective field theory of metric supplemented by
some distinct dynamical coordinates parametrized, in turn, by a scalar quartet
-- the so-called quartet-metric gravity -- the extension of tensor gravity
through a massive scalar graviton in addition to the massless tensor one is
consistently exposed. The field equations for the two realizations of such an
extension originating from the classically equivalent prototype theories -
General Relativity (GR) and its Weyl transverse (WTDiff) alternative - are
derived and argued to be, generally, non-equivalent, with the pure-gravity case
manifesting this explicitly in detail. A splitting of the cosmological constant
onto the gravitating and non-gravitating parts, with a partial screening of the
vacuum energy through an emergent scalar-graviton dark substance, is
considered. A prior importance of treating the WTDiff gravity as a prototype
one on par with GR, when looking for a putative next-to-GR extended theory of
gravity with a scalar-graviton dark substance, is stressed.
| [
{
"created": "Tue, 24 Dec 2019 17:54:41 GMT",
"version": "v1"
}
] | 2019-12-25 | [
[
"Pirogov",
"Yury F.",
""
]
] | In the frameworks of the effective field theory of metric supplemented by some distinct dynamical coordinates parametrized, in turn, by a scalar quartet -- the so-called quartet-metric gravity -- the extension of tensor gravity through a massive scalar graviton in addition to the massless tensor one is consistently exposed. The field equations for the two realizations of such an extension originating from the classically equivalent prototype theories - General Relativity (GR) and its Weyl transverse (WTDiff) alternative - are derived and argued to be, generally, non-equivalent, with the pure-gravity case manifesting this explicitly in detail. A splitting of the cosmological constant onto the gravitating and non-gravitating parts, with a partial screening of the vacuum energy through an emergent scalar-graviton dark substance, is considered. A prior importance of treating the WTDiff gravity as a prototype one on par with GR, when looking for a putative next-to-GR extended theory of gravity with a scalar-graviton dark substance, is stressed. |
gr-qc/0212079 | Sumati Surya | G.J. Galloway, S. Surya, E. Woolgar | Non-Existence of Black Holes in Certain $\Lambda<0$ Spacetimes | 17 pages, Latex. Typos corrected, minor changes to the text. Accepted
for publication in Classical and Quantum Gravity | Class.Quant.Grav. 20 (2003) 1635-1648 | 10.1088/0264-9381/20/9/303 | Alberta-Thy-19-02 | gr-qc hep-th | null | Assuming certain asymptotic conditions, we prove a general theorem on the
non-existence of static regular (i.e., nondegenerate) black holes in spacetimes
with a negative cosmological constant, given that the fundamental group of
space is infinite. We use this to rule out the existence of regular negative
mass AdS black holes with Ricci flat scri. For any mass, we also rule out a
class of conformally compactifiable static black holes whose conformal infinity
has positive scalar curvature and infinite fundamental group, subject to our
asymptotic conditions. In a limited, but important, special case our result
adds new support to the AdS/CFT inspired positive mass conjecture of Horowitz
and Myers.
| [
{
"created": "Thu, 19 Dec 2002 20:52:31 GMT",
"version": "v1"
},
{
"created": "Sat, 8 Mar 2003 00:46:00 GMT",
"version": "v2"
}
] | 2017-08-23 | [
[
"Galloway",
"G. J.",
""
],
[
"Surya",
"S.",
""
],
[
"Woolgar",
"E.",
""
]
] | Assuming certain asymptotic conditions, we prove a general theorem on the non-existence of static regular (i.e., nondegenerate) black holes in spacetimes with a negative cosmological constant, given that the fundamental group of space is infinite. We use this to rule out the existence of regular negative mass AdS black holes with Ricci flat scri. For any mass, we also rule out a class of conformally compactifiable static black holes whose conformal infinity has positive scalar curvature and infinite fundamental group, subject to our asymptotic conditions. In a limited, but important, special case our result adds new support to the AdS/CFT inspired positive mass conjecture of Horowitz and Myers. |
2003.02374 | Zack Carson | Zack Carson and Kent Yagi | Probing beyond-Kerr spacetimes with inspiral-ringdown corrections to
gravitational waves | 18 pages, 4 figures; Updated to match published version | Phys. Rev. D 101, 084050 (2020) | 10.1103/PhysRevD.101.084050 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waves from the explosive merger of distant black holes are
encoded with details regarding the complex extreme-gravity spacetime present at
their source. Famously described by the Kerr spacetime metric for rotating
black holes in general relativity, what if effects beyond this theory are
present? One way to efficiently test this hypothesis is to first obtain a
metric which parametrically deviates from the Kerr metric in a
model-independent way. Given such a metric, one can then predict the ensuing
corrections to both the inspiral and ringdown portions of the gravitational
waveform for black holes present in the new spacetime. With these tools in
hand, one can then test gravitational wave signals for such effects by two
different methods, (i) inspiral-merger-ringdown consistency test, and (ii)
parameterized test. In this paper, we demonstrate the exact recipe one needs to
do just this. We first derive parameterized corrections to the waveform
inspiral, ringdown, and remnant properties for a generic non-Kerr spacetime and
apply this to two example beyond-Kerr spacetimes each parameterized by a single
non-Kerr parameter. We then predict the beyond-Kerr parameter magnitudes
required in an observed gravitational wave signal to be statistically
inconsistent with the Kerr case in general relativity. We find that the two
methods give very similar bounds. The constraints found with existing
gravitational-wave events are comparable to those from x-ray observations,
while future gravitational-wave observations using Cosmic Explorer (Laser
Interferometer Space Antenna) can improve such bounds by two (three) orders of
magnitude.
| [
{
"created": "Wed, 4 Mar 2020 23:56:04 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Apr 2020 23:28:52 GMT",
"version": "v2"
}
] | 2020-04-29 | [
[
"Carson",
"Zack",
""
],
[
"Yagi",
"Kent",
""
]
] | Gravitational waves from the explosive merger of distant black holes are encoded with details regarding the complex extreme-gravity spacetime present at their source. Famously described by the Kerr spacetime metric for rotating black holes in general relativity, what if effects beyond this theory are present? One way to efficiently test this hypothesis is to first obtain a metric which parametrically deviates from the Kerr metric in a model-independent way. Given such a metric, one can then predict the ensuing corrections to both the inspiral and ringdown portions of the gravitational waveform for black holes present in the new spacetime. With these tools in hand, one can then test gravitational wave signals for such effects by two different methods, (i) inspiral-merger-ringdown consistency test, and (ii) parameterized test. In this paper, we demonstrate the exact recipe one needs to do just this. We first derive parameterized corrections to the waveform inspiral, ringdown, and remnant properties for a generic non-Kerr spacetime and apply this to two example beyond-Kerr spacetimes each parameterized by a single non-Kerr parameter. We then predict the beyond-Kerr parameter magnitudes required in an observed gravitational wave signal to be statistically inconsistent with the Kerr case in general relativity. We find that the two methods give very similar bounds. The constraints found with existing gravitational-wave events are comparable to those from x-ray observations, while future gravitational-wave observations using Cosmic Explorer (Laser Interferometer Space Antenna) can improve such bounds by two (three) orders of magnitude. |
1707.01078 | Grasiele Batista Santos | E. Bittencourt, R. Klippert and G. B. Santos | Dynamical Wormhole Definitions Confronted | 14 pages, 21 figures | null | 10.1088/1361-6382/aace31 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Crude comparison between four alternative proposals for the very definition
of a wormhole is provided, all of which were intended to apply to the dynamical
cases. An interesting dynamical solution, based upon large scale magnetic
fields, is used for the comparisons. Such solution goes beyond the perfect
fluid approximation due to an anisotropic pressure component, bringing to the
fore some unsuspected features of those definitions. Certain notions as
reversible traversability are claimed as a way to select among those
definitions the best suited one to represent our intuition of what a wormhole
solution is expected to be.
| [
{
"created": "Tue, 4 Jul 2017 17:30:39 GMT",
"version": "v1"
}
] | 2018-07-25 | [
[
"Bittencourt",
"E.",
""
],
[
"Klippert",
"R.",
""
],
[
"Santos",
"G. B.",
""
]
] | Crude comparison between four alternative proposals for the very definition of a wormhole is provided, all of which were intended to apply to the dynamical cases. An interesting dynamical solution, based upon large scale magnetic fields, is used for the comparisons. Such solution goes beyond the perfect fluid approximation due to an anisotropic pressure component, bringing to the fore some unsuspected features of those definitions. Certain notions as reversible traversability are claimed as a way to select among those definitions the best suited one to represent our intuition of what a wormhole solution is expected to be. |
1101.4913 | Gonzalo Olmo | Gonzalo J. Olmo | Non-singular Universes a la Palatini | 4 pages, no figures. Contribution to the Spanish Relativity Meeting
(ERE2010), 6-10 Sept. Granada, Spain | J.Phys.Conf.Ser.314:012054,2011 | 10.1088/1742-6596/314/1/012054 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has recently been shown that f(R) theories formulated in the Palatini
variational formalism are able to avoid the big bang singularity yielding
instead a bouncing solution. The mechanism responsible for this behavior is
similar to that observed in the effective dynamics of loop quantum cosmology
and an f(R) theory exactly reproducing that dynamics has been found. I will
show here that considering more general actions, with quadratic contributions
of the Ricci tensor, results in a much richer phenomenology that yields
bouncing solutions even in anisotropic (Bianchi I) scenarios. Some implications
of these results are discussed.
| [
{
"created": "Tue, 25 Jan 2011 20:07:36 GMT",
"version": "v1"
}
] | 2011-09-28 | [
[
"Olmo",
"Gonzalo J.",
""
]
] | It has recently been shown that f(R) theories formulated in the Palatini variational formalism are able to avoid the big bang singularity yielding instead a bouncing solution. The mechanism responsible for this behavior is similar to that observed in the effective dynamics of loop quantum cosmology and an f(R) theory exactly reproducing that dynamics has been found. I will show here that considering more general actions, with quadratic contributions of the Ricci tensor, results in a much richer phenomenology that yields bouncing solutions even in anisotropic (Bianchi I) scenarios. Some implications of these results are discussed. |
gr-qc/0101003 | David Wiltshire | D.L. Wiltshire | An introduction to quantum cosmology | 60 pages, harvmac, 11 figures, epsf. These summer school lecture
notes have been available for 5 years; but are being placed on the archive to
make them more easily accessible. Published in "Cosmology: the Physics of the
Universe", eds B. Robson, N. Visvanathan and W.S. Woolcock (World Scientific,
Singapore, 1996) pp 473-531; v2 reference added, typo fixed | null | null | ADP-95-11/M28 | gr-qc | null | This is an introductory set of lecture notes on quantum cosmology, given in
1995 to an audience with interests ranging from astronomy to particle physics.
Topics covered: 1. Introduction: 1.1 Quantum cosmology and quantum gravity; 1.2
A brief history of quantum cosmology. 2. Hamiltonian formulation of general
relativity: 2.1 The 3+1 decomposition; 2.2 The action. 3. Quantisation: 3.1
Superspace; 3.2 Canonical quantisation; 3.3 Path integral quantisation; 3.4
Minisuperspace; 3.5 The WKB approximation; 3.6 Probability measures; 3.7
Minisuperspace for the Friedmann universe with massive scalar field. 4.
Boundary Conditions: 4.1 The no-boundary proposal; 4.2 The tunneling proposal.
5. The predictions of quantum cosmology: 5.1 The period of inflation; 5.2 The
origin of density perturbations; 5.3 The arrow of time.
| [
{
"created": "Sat, 30 Dec 2000 07:25:47 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Sep 2003 07:38:56 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Wiltshire",
"D. L.",
""
]
] | This is an introductory set of lecture notes on quantum cosmology, given in 1995 to an audience with interests ranging from astronomy to particle physics. Topics covered: 1. Introduction: 1.1 Quantum cosmology and quantum gravity; 1.2 A brief history of quantum cosmology. 2. Hamiltonian formulation of general relativity: 2.1 The 3+1 decomposition; 2.2 The action. 3. Quantisation: 3.1 Superspace; 3.2 Canonical quantisation; 3.3 Path integral quantisation; 3.4 Minisuperspace; 3.5 The WKB approximation; 3.6 Probability measures; 3.7 Minisuperspace for the Friedmann universe with massive scalar field. 4. Boundary Conditions: 4.1 The no-boundary proposal; 4.2 The tunneling proposal. 5. The predictions of quantum cosmology: 5.1 The period of inflation; 5.2 The origin of density perturbations; 5.3 The arrow of time. |
2406.05767 | Vaidik A Sharma | Vaidik A Sharma | Integrating Quantum Algorithms with Gravitational-Wave Metrology for
Enhanced Signal Detection | null | International Journal of Innovative Science and Research
Technology(IJISRT) Volume 9 - 2024, Issue 5 - May | 10.38124/ijisrt/IJISRT24MAY1808 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | This study explores the integration of quantum algorithms, specifically
Grover's algorithm, with quantum metrology to enhance the efficiency and
sensitivity of gravitational-wave detection. By combining quantum matched
filtering with precise parameter estimation techniques, the research aims to
optimize sensor networks for the identification of gravitational waves. This
integrated approach leverages the strengths of quantum superposition and
entanglement to improve signal detection, reduce noise, and strategically place
sensors. The findings demonstrate significant improvements in the sensitivity
and accuracy of gravitational wave measurements, highlighting the potential of
quantum technologies to revolutionize observational astronomy and enhance our
understanding of the universe.
| [
{
"created": "Sun, 9 Jun 2024 12:46:44 GMT",
"version": "v1"
}
] | 2024-06-13 | [
[
"Sharma",
"Vaidik A",
""
]
] | This study explores the integration of quantum algorithms, specifically Grover's algorithm, with quantum metrology to enhance the efficiency and sensitivity of gravitational-wave detection. By combining quantum matched filtering with precise parameter estimation techniques, the research aims to optimize sensor networks for the identification of gravitational waves. This integrated approach leverages the strengths of quantum superposition and entanglement to improve signal detection, reduce noise, and strategically place sensors. The findings demonstrate significant improvements in the sensitivity and accuracy of gravitational wave measurements, highlighting the potential of quantum technologies to revolutionize observational astronomy and enhance our understanding of the universe. |
gr-qc/0607122 | Ramin G. Daghigh | R. G. Daghigh, J. Gegenberg, G. Kunstatter | A Partially Gauged Fixed Hamiltonian for Scalar Field Collapse | 13 pages | Class.Quant.Grav.24:2099-2107,2007 | 10.1088/0264-9381/24/8/010 | null | gr-qc | null | We derive a partially gauge fixed Hamiltonian for black hole formation via
real scalar field collapse. The class of models considered includes many
theories of physical interest, including spherically symmetric black holes in
$D$ spacetime dimensions. The boundary and gauge fixing conditions are chosen
to be consistent with generalized Painleve-Gullstrand coordinates, in which the
metric is regular across the black hole future horizon. The resulting
Hamiltonian is remarkably simple and we argue that it provides a good starting
point for studying the quantum dynamics of black hole formation.
| [
{
"created": "Wed, 26 Jul 2006 18:34:52 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Aug 2007 21:03:51 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Daghigh",
"R. G.",
""
],
[
"Gegenberg",
"J.",
""
],
[
"Kunstatter",
"G.",
""
]
] | We derive a partially gauge fixed Hamiltonian for black hole formation via real scalar field collapse. The class of models considered includes many theories of physical interest, including spherically symmetric black holes in $D$ spacetime dimensions. The boundary and gauge fixing conditions are chosen to be consistent with generalized Painleve-Gullstrand coordinates, in which the metric is regular across the black hole future horizon. The resulting Hamiltonian is remarkably simple and we argue that it provides a good starting point for studying the quantum dynamics of black hole formation. |
gr-qc/0008058 | Scott A. Hughes | Scott A. Hughes | Gravitational waves from extreme mass ratio inspirals: Challenges in
mapping the spacetime of massive, compact objects | 6 pages, 2 figures. To appear (modulo refereeing) in the Proceedings
of the 3rd International LISA Symposium | Class.Quant.Grav. 18 (2001) 4067-4074 | 10.1088/0264-9381/18/19/314 | null | gr-qc astro-ph | null | In its final year of inspiral, a stellar mass ($1 - 10 M_\odot$) body orbits
a massive ($10^5 - 10^7 M_\odot$) compact object about $10^5$ times, spiralling
from several Schwarzschild radii to the last stable orbit. These orbits are
deep in the massive object's strong field, so the gravitational waves that they
produce probe the strong field nature of the object's spacetime. Measuring
these waves can, in principle, be used to ``map'' this spacetime, allowing
observers to test whether the object is a black hole or something more exotic.
Such measurements will require a good theoretical understanding of wave
generation during inspiral. In this article, I discuss the major theoretical
challenges standing in the way of building such maps from gravitational-wave
observations, as well as recent progress in producing extreme mass ratio
inspirals and waveforms.
| [
{
"created": "Wed, 23 Aug 2000 21:20:46 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Hughes",
"Scott A.",
""
]
] | In its final year of inspiral, a stellar mass ($1 - 10 M_\odot$) body orbits a massive ($10^5 - 10^7 M_\odot$) compact object about $10^5$ times, spiralling from several Schwarzschild radii to the last stable orbit. These orbits are deep in the massive object's strong field, so the gravitational waves that they produce probe the strong field nature of the object's spacetime. Measuring these waves can, in principle, be used to ``map'' this spacetime, allowing observers to test whether the object is a black hole or something more exotic. Such measurements will require a good theoretical understanding of wave generation during inspiral. In this article, I discuss the major theoretical challenges standing in the way of building such maps from gravitational-wave observations, as well as recent progress in producing extreme mass ratio inspirals and waveforms. |
gr-qc/0602048 | M. D. Maia | M. D. Maia | The Extended ADS/CFT Correspondence | 3 pages, Revtex4, no figures | Braz.J.Phys.35:1142-1144,2005 | 10.1590/S0103-97332005000700037 | null | gr-qc | null | The correspondence between conformal covariant fields in Minkowski's
space-time and isometric fields in the five dimensional anti-deSitter
space-time is extended to a six-dimensional bulk space and its regular
sub-manifolds, so as to include the analysis of evaporating Schwarzschild's
black holes without loss of quantum unitarity.
| [
{
"created": "Mon, 13 Feb 2006 18:51:26 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Maia",
"M. D.",
""
]
] | The correspondence between conformal covariant fields in Minkowski's space-time and isometric fields in the five dimensional anti-deSitter space-time is extended to a six-dimensional bulk space and its regular sub-manifolds, so as to include the analysis of evaporating Schwarzschild's black holes without loss of quantum unitarity. |
2405.20442 | Ernesto Contreras | M. Carrasco, N. M. Santos and E. Contreras | Spontaneous scalarization in Einstein--power--Maxwell--scalar models | null | Physics of the Dark Universe, Volume 45, 2024, 101529, ISSN
2212-6864 | 10.1016/j.dark.2024.101529. | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the spontaneous scalarization of charged black holes in Einstein's
gravity minimally coupled to power--Maxwell electrodynamics which, in turn, is
non--minimally coupled to a real scalar field. We point out the existence of a
specific power for which the scalarized solution is well-behaved, and
entropically preferred in comparison to the scalar-free charged black hole
solution.
| [
{
"created": "Thu, 30 May 2024 19:38:37 GMT",
"version": "v1"
}
] | 2024-06-03 | [
[
"Carrasco",
"M.",
""
],
[
"Santos",
"N. M.",
""
],
[
"Contreras",
"E.",
""
]
] | We study the spontaneous scalarization of charged black holes in Einstein's gravity minimally coupled to power--Maxwell electrodynamics which, in turn, is non--minimally coupled to a real scalar field. We point out the existence of a specific power for which the scalarized solution is well-behaved, and entropically preferred in comparison to the scalar-free charged black hole solution. |
1108.6059 | Steffen Gielen | Steffen Gielen | 2-point functions in quantum cosmology | 4 pages, based on a talk given at Loops '11, Madrid, to appear in
Journal of Physics: Conference Series (JPCS) | J. Phys.: Conf. Ser. 360 (2012) 012029 | 10.1088/1742-6596/360/1/012029 | AEI-2011-085 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the path-integral formulation of quantum cosmology with a massless
scalar field as a sum-over-histories, with particular reference to loop quantum
cosmology. Exploiting the analogy with the relativistic particle, we give a
complete overview of the possible two-point functions, deriving vertex
expansions and composition laws they satisfy. We clarify the tie between
definitions using a group averaging procedure and those in a deparametrised
framework. We draw some conclusions about the physics of a single quantum
universe and multiverse field theories where the role of these sectors and the
inner product are reinterpreted.
| [
{
"created": "Tue, 30 Aug 2011 20:00:03 GMT",
"version": "v1"
}
] | 2012-06-05 | [
[
"Gielen",
"Steffen",
""
]
] | We discuss the path-integral formulation of quantum cosmology with a massless scalar field as a sum-over-histories, with particular reference to loop quantum cosmology. Exploiting the analogy with the relativistic particle, we give a complete overview of the possible two-point functions, deriving vertex expansions and composition laws they satisfy. We clarify the tie between definitions using a group averaging procedure and those in a deparametrised framework. We draw some conclusions about the physics of a single quantum universe and multiverse field theories where the role of these sectors and the inner product are reinterpreted. |
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