id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1006.3926 | Xiang-Song Chen | Xiang-Song Chen and Ben-Chao Zhu | Physical decomposition of the gauge and gravitational fields | 11 pages, no figure; significant revision, with discussion on
relations of various metric decompositions | Phys.Rev.D83:084006,2011 | 10.1103/PhysRevD.83.084006 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Physical decomposition of the non-Abelian gauge field has recently solved the
two-decade-lasting problem of a meaningful gluon spin. Here we extend this
approach to gravity and attack the century-lasting problem of a meaningful
gravitational energy. The metric is unambiguously separated into a pure
geometric term which contributes null curvature tensor, and a physical term
which represents the true gravitational effect and always vanishes in a flat
space-time. By this decomposition the conventional pseudo-tensors of the
gravitational stress-energy are easily rescued to produce definite physical
result. Our decomposition applies to any symmetric tensor, and has interesting
relation to the transverse-traceless (TT) decomposition discussed by Arnowitt,
Deser and Misner, and by York.
| [
{
"created": "Sun, 20 Jun 2010 11:17:07 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Jun 2010 08:03:27 GMT",
"version": "v2"
},
{
"created": "Wed, 19 Jan 2011 12:30:33 GMT",
"version": "v3"
}
] | 2011-04-22 | [
[
"Chen",
"Xiang-Song",
""
],
[
"Zhu",
"Ben-Chao",
""
]
] | Physical decomposition of the non-Abelian gauge field has recently solved the two-decade-lasting problem of a meaningful gluon spin. Here we extend this approach to gravity and attack the century-lasting problem of a meaningful gravitational energy. The metric is unambiguously separated into a pure geometric term which contributes null curvature tensor, and a physical term which represents the true gravitational effect and always vanishes in a flat space-time. By this decomposition the conventional pseudo-tensors of the gravitational stress-energy are easily rescued to produce definite physical result. Our decomposition applies to any symmetric tensor, and has interesting relation to the transverse-traceless (TT) decomposition discussed by Arnowitt, Deser and Misner, and by York. |
gr-qc/0302116 | Graham Shore | G.M. Shore | Causality and Superluminal Light | 22 pages, 5 figures; prepared for the proceedings of the conference
`Time and Matter', Venice, August 2002 | null | null | SWAT/03-372 | gr-qc hep-th | null | The causal properties of curved spacetime, which underpin our sense of time
in gravitational theories, are defined by the null cones of the spacetime
metric. In classical general relativity, it is assumed that these coincide with
the light cones determined by the physical propagation of light rays. However,
the quantum vacuum acts as a dispersive medium for the propagation of light,
since vacuum polarisation in QED induces interactions which effectively violate
the strong equivalence principle (SEP). For low frequencies the phenomenon of
gravitational birefringence occurs and indeed, for some metrics and
polarisations, photons may acquire {\it superluminal} phase velocities. In this
article, we review some of the remarkable features of SEP violating
superluminal propagation in curved spacetime and discuss recent progress on the
issue of dispersion, explaining why it is the high-frequency limit of the phase
velocity that determines the characteristics of the effective wave equation and
thus the physical causal structure.
| [
{
"created": "Thu, 27 Feb 2003 19:29:04 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Shore",
"G. M.",
""
]
] | The causal properties of curved spacetime, which underpin our sense of time in gravitational theories, are defined by the null cones of the spacetime metric. In classical general relativity, it is assumed that these coincide with the light cones determined by the physical propagation of light rays. However, the quantum vacuum acts as a dispersive medium for the propagation of light, since vacuum polarisation in QED induces interactions which effectively violate the strong equivalence principle (SEP). For low frequencies the phenomenon of gravitational birefringence occurs and indeed, for some metrics and polarisations, photons may acquire {\it superluminal} phase velocities. In this article, we review some of the remarkable features of SEP violating superluminal propagation in curved spacetime and discuss recent progress on the issue of dispersion, explaining why it is the high-frequency limit of the phase velocity that determines the characteristics of the effective wave equation and thus the physical causal structure. |
0812.3310 | Joan Josep Ferrando | Joan Josep Ferrando, Juan Antonio S\'aez | An intrinsic characterization of the Kerr metric | 15 pages; v2: necessary conditions added to theorems 1 and 2, other
minor changes | Class.Quant.Grav.26:075013,2009 | 10.1088/0264-9381/26/7/075013 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give the necessary and sufficient (local) conditions for a metric tensor
to be the Kerr solution. These conditions exclusively involve explicit
concomitants of the Riemann tensor.
| [
{
"created": "Wed, 17 Dec 2008 15:00:04 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Feb 2009 14:03:01 GMT",
"version": "v2"
}
] | 2009-03-24 | [
[
"Ferrando",
"Joan Josep",
""
],
[
"Sáez",
"Juan Antonio",
""
]
] | We give the necessary and sufficient (local) conditions for a metric tensor to be the Kerr solution. These conditions exclusively involve explicit concomitants of the Riemann tensor. |
1101.2809 | Xiang-Song Chen | Xiang-Song Chen and Ben-Chao Zhu | Tensor gauge condition and tensor field decomposition | significant revision with extended discussion | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss various proposals of separating a tensor field into pure-gauge and
gauge-invariant components. Such tensor field decomposition is intimately
related to the effort of identifying the real gravitational degrees of freedom
out of the metric tensor in Einstein's general relativity. We show that, as for
a vector field, the tensor field decomposition has exact correspondence to, and
can be derived from, the gauge-fixing approach. The complication for the tensor
field, however, is that there are infinitely many complete gauge conditions, in
contrast to the uniqueness of Coulomb gauge for a vector field. We make an
extensive exploration of these tensor gauge conditions and their corresponding
tensor field decompositions, regarding mathematical structures, equations of
motion, nonlinear properties; and show that apparently no single choice is
superior in all aspects.
| [
{
"created": "Fri, 14 Jan 2011 13:57:01 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Jan 2011 12:47:01 GMT",
"version": "v2"
},
{
"created": "Thu, 17 Mar 2011 02:19:08 GMT",
"version": "v3"
},
{
"created": "Mon, 16 May 2011 14:02:52 GMT",
"version": "v4"
},
{
"c... | 2011-11-30 | [
[
"Chen",
"Xiang-Song",
""
],
[
"Zhu",
"Ben-Chao",
""
]
] | We discuss various proposals of separating a tensor field into pure-gauge and gauge-invariant components. Such tensor field decomposition is intimately related to the effort of identifying the real gravitational degrees of freedom out of the metric tensor in Einstein's general relativity. We show that, as for a vector field, the tensor field decomposition has exact correspondence to, and can be derived from, the gauge-fixing approach. The complication for the tensor field, however, is that there are infinitely many complete gauge conditions, in contrast to the uniqueness of Coulomb gauge for a vector field. We make an extensive exploration of these tensor gauge conditions and their corresponding tensor field decompositions, regarding mathematical structures, equations of motion, nonlinear properties; and show that apparently no single choice is superior in all aspects. |
1806.01625 | Tim Dietrich | Tim Dietrich, David Radice, Sebastiano Bernuzzi, Francesco Zappa,
Albino Perego, Bernd Brueugmann, Swami Vivekanandji Chaurasia, Reetika Dudi,
Wolfgang Tichy, Maximiliano Ujevic | CoRe database of binary neutron star merger waveforms and its
application in waveform development | Waveform database is online available at
http://www.computational-relativity.org/ | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the Computational Relativity CoRe collaboration's public database
of gravitational waveforms from binary neutron star mergers. The database
currently contains 367 waveforms from numerical simulations that are consistent
with general relativity and that employ constraint satisfying initial data in
hydrodynamical equilibrium. It spans 164 physically distinct configuration with
different binary parameters (total binary mass, mass-ratio, initial separation,
eccentricity, and stars' spins) and simulated physics. Waveforms computed at
multiple grid resolutions and extraction radii are provided for controlling
numerical uncertainties. We also release an exemplary set of 18 hybrid
waveforms constructed with a state-of-art effective-one-body model spanning the
frequency band of advanced gravitational-wave detectors. We outline present and
future applications of the database to gravitational-wave astronomy.
| [
{
"created": "Tue, 5 Jun 2018 12:14:30 GMT",
"version": "v1"
}
] | 2018-06-06 | [
[
"Dietrich",
"Tim",
""
],
[
"Radice",
"David",
""
],
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Zappa",
"Francesco",
""
],
[
"Perego",
"Albino",
""
],
[
"Brueugmann",
"Bernd",
""
],
[
"Chaurasia",
"Swami Vivekanandji"... | We present the Computational Relativity CoRe collaboration's public database of gravitational waveforms from binary neutron star mergers. The database currently contains 367 waveforms from numerical simulations that are consistent with general relativity and that employ constraint satisfying initial data in hydrodynamical equilibrium. It spans 164 physically distinct configuration with different binary parameters (total binary mass, mass-ratio, initial separation, eccentricity, and stars' spins) and simulated physics. Waveforms computed at multiple grid resolutions and extraction radii are provided for controlling numerical uncertainties. We also release an exemplary set of 18 hybrid waveforms constructed with a state-of-art effective-one-body model spanning the frequency band of advanced gravitational-wave detectors. We outline present and future applications of the database to gravitational-wave astronomy. |
2204.12949 | Jo\~ao Lu\'is Rosa | Jo\~ao Lu\'is Rosa, Diego Rubiera-Garcia | Shadows of boson and Proca stars with thin accretion disks | 15 pages, 7 figures | Phys. Rev. D 106, 084004 (2022) | 10.1103/PhysRevD.106.084004 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we obtain the shadow images of spherically symmetric scalar
boson and Proca stars using analytical fittings of numerical solutions, when
illuminated by a geometrically thin accretion disk. We chose a sample of four
boson and four Proca stars with radii ranging from more compact configurations
with $R\sim 9M$ to more dilute configurations with $R\sim 20M$, where $M$ is
the total mass of the bosonic star. In these configurations, the absence of the
photon sphere (the locus of unstable bound geodesics) makes the optical
appearance of these stars to be dominated by a single luminous ring enclosing a
central brightness depression, and no further light rings are available. We
show that if one considers face-on observations and a disk model whose emission
is truncated at some finite radius at which the luminosity attains its maximum
value, both the size of the shadow, as well as the luminosity and depth of the
bright region, are heavily influenced by the emission profile, with the choice
of the type and parameters of the bosonic stars in our samples having a
sub-dominant influence. These differences are nonetheless significantly
magnified when one allows the accretion disk to extend close enough to the
center of the star. Our results point out that even though bosonic stars are
horizonless and do not have a photon sphere, some of them may be able to
produce conventional black hole shadow-like images provided that their
compactness is large enough, thus being potentially consistent with current and
future observations.
| [
{
"created": "Wed, 27 Apr 2022 13:59:07 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Oct 2022 15:57:40 GMT",
"version": "v2"
}
] | 2022-10-11 | [
[
"Rosa",
"João Luís",
""
],
[
"Rubiera-Garcia",
"Diego",
""
]
] | In this work, we obtain the shadow images of spherically symmetric scalar boson and Proca stars using analytical fittings of numerical solutions, when illuminated by a geometrically thin accretion disk. We chose a sample of four boson and four Proca stars with radii ranging from more compact configurations with $R\sim 9M$ to more dilute configurations with $R\sim 20M$, where $M$ is the total mass of the bosonic star. In these configurations, the absence of the photon sphere (the locus of unstable bound geodesics) makes the optical appearance of these stars to be dominated by a single luminous ring enclosing a central brightness depression, and no further light rings are available. We show that if one considers face-on observations and a disk model whose emission is truncated at some finite radius at which the luminosity attains its maximum value, both the size of the shadow, as well as the luminosity and depth of the bright region, are heavily influenced by the emission profile, with the choice of the type and parameters of the bosonic stars in our samples having a sub-dominant influence. These differences are nonetheless significantly magnified when one allows the accretion disk to extend close enough to the center of the star. Our results point out that even though bosonic stars are horizonless and do not have a photon sphere, some of them may be able to produce conventional black hole shadow-like images provided that their compactness is large enough, thus being potentially consistent with current and future observations. |
1312.0725 | Yi Xie | Xue-Mei Deng and Yi Xie | Spacecraft Doppler tracking with possible violations of LLI and LPI: a
theoretical modeling | 10 pages; Accepted for publication in Research in Astronomy and
Astrophysics (RAA) | null | 10.1088/1674-4527/14/3/006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Currently two-way and three-way spacecraft Doppler tracking techniques are
widely used and playing important roles in control and navigation for deep
space missions. Starting from one-way Doppler model, we extend the models of
two-way and three-way Doppler by making them include possible violations of the
local Lorentz invariance (LLI) and the local position invariance (LPI) in order
to test the Einstein equivalence principle which is the cornerstone of general
relativity and all other metric theories of gravity. After taking the finite
speed of light into account, which is so-called light-time solution (LTS), we
have these models depending on the time of reception of the signal only for
practical convenience. We find that possible violations of LLI and LPI can not
affect two-way Doppler under linear approximation of LTS although this
approximation is sufficiently good for most cases in the solar system. We also
show that, in three-way Doppler, possible violations of LLI and LPI associate
with two stations only, which suggests that it is better to set the stations at
places with significant differences in velocities and gravitational potentials
to obtain high level of sensitivity for tests.
| [
{
"created": "Tue, 3 Dec 2013 08:11:31 GMT",
"version": "v1"
}
] | 2014-03-05 | [
[
"Deng",
"Xue-Mei",
""
],
[
"Xie",
"Yi",
""
]
] | Currently two-way and three-way spacecraft Doppler tracking techniques are widely used and playing important roles in control and navigation for deep space missions. Starting from one-way Doppler model, we extend the models of two-way and three-way Doppler by making them include possible violations of the local Lorentz invariance (LLI) and the local position invariance (LPI) in order to test the Einstein equivalence principle which is the cornerstone of general relativity and all other metric theories of gravity. After taking the finite speed of light into account, which is so-called light-time solution (LTS), we have these models depending on the time of reception of the signal only for practical convenience. We find that possible violations of LLI and LPI can not affect two-way Doppler under linear approximation of LTS although this approximation is sufficiently good for most cases in the solar system. We also show that, in three-way Doppler, possible violations of LLI and LPI associate with two stations only, which suggests that it is better to set the stations at places with significant differences in velocities and gravitational potentials to obtain high level of sensitivity for tests. |
1202.2540 | Diego S\'aez-G\'omez | Salvatore Capozziello and Diego S\'aez-G\'omez | Conformal frames and the validity of Birkhoff's theorem | 4 pages. Contribution to the Proceedings of Spanish Relativity
Meeting ERE2011, Madrid | null | 10.1063/1.4734431 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Birkhoff's theorem is one of the most important statements of Einstein's
general relativity, which generally can not be extended to modified theories of
gravity. Here we study the validity of the theorem in scalar-tensor theories
using a perturbative approach, and compare the results in the so-called
Einstein and Jordan frames. The implications of the results question the
physical equivalence between both frames, at least in perturbations.
| [
{
"created": "Sun, 12 Feb 2012 16:13:47 GMT",
"version": "v1"
}
] | 2015-06-04 | [
[
"Capozziello",
"Salvatore",
""
],
[
"Sáez-Gómez",
"Diego",
""
]
] | Birkhoff's theorem is one of the most important statements of Einstein's general relativity, which generally can not be extended to modified theories of gravity. Here we study the validity of the theorem in scalar-tensor theories using a perturbative approach, and compare the results in the so-called Einstein and Jordan frames. The implications of the results question the physical equivalence between both frames, at least in perturbations. |
1705.09232 | Uma Papnoi | Ravi Shankar Kuniyal, Hemwati Nandan, Uma Papnoi, Rashmi Uniyal, K D
Purohit | Strong lensing and Observables around 5D Myers-Perry black hole
spacetime | 11 pages two column, 7 figures,Title, text and figures modified,
Accepted for publication in Modern Physics Letter A | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the motion of massless test particles in a five dimensional (5D)
Myers-Perry black hole spacetime with two spin parameters. The behaviour of the
effective potential in view of different values of black hole parameters is
discussed in the equatorial plane. The frequency shift of photons is calculated
which is found to depend on the spin parameter of black hole and the observed
redshift is discussed accordingly. The deflection angle and the strong
deflection limit coefficients are also calculated and their behaviour with the
spin parameters is analysed in detail. It is observed that the behaviour of
both deflection angle and strong field coefficient differs from Kerr black hole
spacetime in four dimensions (4D) in General Relativity (GR) which is mainly
due to the presence of two spin parameters in higher dimension.
| [
{
"created": "Thu, 25 May 2017 15:35:56 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Jun 2018 07:47:06 GMT",
"version": "v2"
}
] | 2018-06-13 | [
[
"Kuniyal",
"Ravi Shankar",
""
],
[
"Nandan",
"Hemwati",
""
],
[
"Papnoi",
"Uma",
""
],
[
"Uniyal",
"Rashmi",
""
],
[
"Purohit",
"K D",
""
]
] | We study the motion of massless test particles in a five dimensional (5D) Myers-Perry black hole spacetime with two spin parameters. The behaviour of the effective potential in view of different values of black hole parameters is discussed in the equatorial plane. The frequency shift of photons is calculated which is found to depend on the spin parameter of black hole and the observed redshift is discussed accordingly. The deflection angle and the strong deflection limit coefficients are also calculated and their behaviour with the spin parameters is analysed in detail. It is observed that the behaviour of both deflection angle and strong field coefficient differs from Kerr black hole spacetime in four dimensions (4D) in General Relativity (GR) which is mainly due to the presence of two spin parameters in higher dimension. |
1109.4838 | Alexey Golovnev | Alexey Golovnev | On cosmic inflation in vector field theories | 10 pages; a few minor typos corrected; published version | Classical and Quantum Gravity, 28 (2011), 245018 | 10.1088/0264-9381/28/24/245018 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the longitudinal ghost issue in Abelian vector inflation. It
turns out that, within the class of Lorentz-invariant vector field theories
with three degrees of freedom and without any extra (scalar) fields, the
possibilities are essentially exhausted by the classical solution due to Larry
Ford with an extremely flat potential which doesn't feel the fast roll of its
argument. And, moreover, one needs to fulfil an extra condition on that
potential in order to avoid severe gradient instability. At the same time, some
Lorentz-violating modifications are worth to be explored.
| [
{
"created": "Thu, 22 Sep 2011 15:01:30 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Sep 2011 11:09:42 GMT",
"version": "v2"
},
{
"created": "Wed, 9 Nov 2011 11:08:49 GMT",
"version": "v3"
},
{
"created": "Thu, 24 Nov 2011 15:52:39 GMT",
"version": "v4"
}
] | 2011-12-02 | [
[
"Golovnev",
"Alexey",
""
]
] | We investigate the longitudinal ghost issue in Abelian vector inflation. It turns out that, within the class of Lorentz-invariant vector field theories with three degrees of freedom and without any extra (scalar) fields, the possibilities are essentially exhausted by the classical solution due to Larry Ford with an extremely flat potential which doesn't feel the fast roll of its argument. And, moreover, one needs to fulfil an extra condition on that potential in order to avoid severe gradient instability. At the same time, some Lorentz-violating modifications are worth to be explored. |
2107.02634 | Riccardo Sturani | Gabriel Luz Almeida, Stefano Foffa, Riccardo Sturani | Gravitational Multipole Renormalization | 20 pages, 1 figure. Typos corrected in v2, which is the version
published in PRD | null | 10.1103/PhysRevD.104.084095 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We compute the effect of scattering gravitational radiation off the static
background curvature, up to second order in Newton constant, known in
literature as tail and tail-of-tail processes, for generic electric and
magnetic multipoles. Starting from the multipole expansion of composite compact
objects, and as expected due to the known electric quadrupole case, both long-
and short-distance (UV) divergences are encountered. The former disappears from
properly defined observables, the latter are renormalized and their associated
logarithms give rise to a classical renormalization group flow. UV divergences
alert for incompleteness of the multipolar description of the composite source,
and are expected not to be present in a UV-complete theory, as explicitly
derived in literature for the case of conservative dynamics. Logarithmic terms
from tail-of-tail processes associated to generic magnetic multipoles are
computed in this work for the first time.
| [
{
"created": "Tue, 6 Jul 2021 14:18:52 GMT",
"version": "v1"
},
{
"created": "Fri, 29 Oct 2021 16:18:16 GMT",
"version": "v2"
}
] | 2021-11-10 | [
[
"Almeida",
"Gabriel Luz",
""
],
[
"Foffa",
"Stefano",
""
],
[
"Sturani",
"Riccardo",
""
]
] | We compute the effect of scattering gravitational radiation off the static background curvature, up to second order in Newton constant, known in literature as tail and tail-of-tail processes, for generic electric and magnetic multipoles. Starting from the multipole expansion of composite compact objects, and as expected due to the known electric quadrupole case, both long- and short-distance (UV) divergences are encountered. The former disappears from properly defined observables, the latter are renormalized and their associated logarithms give rise to a classical renormalization group flow. UV divergences alert for incompleteness of the multipolar description of the composite source, and are expected not to be present in a UV-complete theory, as explicitly derived in literature for the case of conservative dynamics. Logarithmic terms from tail-of-tail processes associated to generic magnetic multipoles are computed in this work for the first time. |
0805.4067 | Yi Xie | Yi Xie, Tian-Yi Huang | Second post-Newtonian approximation of Einstein-aether theory | 29 pages, no figures | Phys. Rev. D 77, 124049 (2008) | 10.1103/PhysRevD.77.124049 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, second post-Newtonian approximation of Einstein-aether theory
is obtained by Chandrasekhar's approach. Five parameterized post-Newtonian
parameters in first post-Newtonian approximation are presented after a time
transformation and they are identical with previous works, in which $\gamma=1$,
$\beta=1$ and two preferred-frame parameters remain. Meanwhile, in second
post-Newtonian approximation, a parameter, which represents third order
nonlinearity for gravity, is zero the same as in general relativity. For an
application for future deep space laser ranging missions, we reduce the metric
coefficients for light propagation in a case of $N$ point masses as a
simplified model of the solar system. The resulting light deflection angle in
second post-Newtonian approximation poses another constraint on the
Einstein-aether theory.
| [
{
"created": "Tue, 27 May 2008 10:25:20 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Jul 2008 08:19:40 GMT",
"version": "v2"
}
] | 2009-02-14 | [
[
"Xie",
"Yi",
""
],
[
"Huang",
"Tian-Yi",
""
]
] | In this paper, second post-Newtonian approximation of Einstein-aether theory is obtained by Chandrasekhar's approach. Five parameterized post-Newtonian parameters in first post-Newtonian approximation are presented after a time transformation and they are identical with previous works, in which $\gamma=1$, $\beta=1$ and two preferred-frame parameters remain. Meanwhile, in second post-Newtonian approximation, a parameter, which represents third order nonlinearity for gravity, is zero the same as in general relativity. For an application for future deep space laser ranging missions, we reduce the metric coefficients for light propagation in a case of $N$ point masses as a simplified model of the solar system. The resulting light deflection angle in second post-Newtonian approximation poses another constraint on the Einstein-aether theory. |
gr-qc/0503055 | Kirill Bronnikov | S.T. Abdyrakhmanov, K.A. Bronnikov, B.E. Meierovich | Uniqueness of RS2 type thick branes supported by a scalar field | 5 pages, no figures, gc style. Submitted to Proc. Int. Conf.
Cosmion-2004 | Grav.Cosmol. 11 (2005) 82-86 | null | null | gr-qc | null | We study thick brane world models as Z_2-symmetric domain walls supported by
a scalar field with an arbitrary potential V(\phi) in 5D general relativity.
Under the global regularity requirement, such configurations (i) have always an
AdS asymptotic far from the brane, (ii) are only possible if V(\phi) has an
alternating sign and (iii) V(\phi) should satisfy a certain fine-tuning type
equality. Thus a thick brane with any admissible V(\phi) is a regularized
version of the RS2 brane immersed in the AdS_5 bulk. The thin brane limit is
realized in a universal manner by including an arbitrary thick brane model in a
one-parameter family, where the parameter "a" is associated with brane
thickness; the asymptotic value of V(\phi) (related to \Lambda_5, the effective
cosmological constant) remains a-independent. The problem of ordinary matter
confinement on the brane is discussed for a test scalar field. Its
stress-energy tensor is found to diverge at the AdS horizon for both thin and
thick branes, making a serious problem for this class of brane world models.
| [
{
"created": "Sun, 13 Mar 2005 11:05:45 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Abdyrakhmanov",
"S. T.",
""
],
[
"Bronnikov",
"K. A.",
""
],
[
"Meierovich",
"B. E.",
""
]
] | We study thick brane world models as Z_2-symmetric domain walls supported by a scalar field with an arbitrary potential V(\phi) in 5D general relativity. Under the global regularity requirement, such configurations (i) have always an AdS asymptotic far from the brane, (ii) are only possible if V(\phi) has an alternating sign and (iii) V(\phi) should satisfy a certain fine-tuning type equality. Thus a thick brane with any admissible V(\phi) is a regularized version of the RS2 brane immersed in the AdS_5 bulk. The thin brane limit is realized in a universal manner by including an arbitrary thick brane model in a one-parameter family, where the parameter "a" is associated with brane thickness; the asymptotic value of V(\phi) (related to \Lambda_5, the effective cosmological constant) remains a-independent. The problem of ordinary matter confinement on the brane is discussed for a test scalar field. Its stress-energy tensor is found to diverge at the AdS horizon for both thin and thick branes, making a serious problem for this class of brane world models. |
1901.01253 | Peng Xu | Peng Xu, Zhi Wang, Li-E Qiang | Towards Constraining Parity-Violations in Gravity with Satellite
Gradiometry | 15 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1606.08183 | Physics Letters B, 789, 378-386 (2019) | 10.1016/j.physletb.2018.12.049 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Parity violation in gravity, if existed, could have important implications,
and it is meaningful to search and test the possible observational effects.
Chern-Simons modified gravity serves as a natural model for gravitational
parity-violations. Especially, considering extensions to Einstein-Hilbert
action up to second order curvature terms, it is known that theories of
gravitational parity-violation will reduce to the dynamical Chern-Simons
gravity. In this letter, we outline the theoretical principles of testing the
dynamical Chern-Simons gravity with orbiting gravity gradiometers, which could
be naturally incorporated into future satellite gravity missions. The secular
gravity gradient signals, due to the Mashhoon-Theiss (anomaly) effect, in
dynamical Chern-Simons gravity are worked out, which can improve the constraint
of the corresponding Chern-Simons length scale $\xi^{\frac{1}{4}}_{cs}$
obtained from such measurement scheme. For orbiting superconducting
gradiometers or gradiometers with optical readout, a bound
$\xi^{\frac{1}{4}}_{cs}\leq 10^6 \ km$ (or even better) could in principle be
obtained, which will be at least 2 orders of magnitude stronger than the
current one based on the observations from the GP-B mission and the LAGEOS I,
II satellites.
| [
{
"created": "Fri, 4 Jan 2019 10:05:24 GMT",
"version": "v1"
}
] | 2019-01-08 | [
[
"Xu",
"Peng",
""
],
[
"Wang",
"Zhi",
""
],
[
"Qiang",
"Li-E",
""
]
] | Parity violation in gravity, if existed, could have important implications, and it is meaningful to search and test the possible observational effects. Chern-Simons modified gravity serves as a natural model for gravitational parity-violations. Especially, considering extensions to Einstein-Hilbert action up to second order curvature terms, it is known that theories of gravitational parity-violation will reduce to the dynamical Chern-Simons gravity. In this letter, we outline the theoretical principles of testing the dynamical Chern-Simons gravity with orbiting gravity gradiometers, which could be naturally incorporated into future satellite gravity missions. The secular gravity gradient signals, due to the Mashhoon-Theiss (anomaly) effect, in dynamical Chern-Simons gravity are worked out, which can improve the constraint of the corresponding Chern-Simons length scale $\xi^{\frac{1}{4}}_{cs}$ obtained from such measurement scheme. For orbiting superconducting gradiometers or gradiometers with optical readout, a bound $\xi^{\frac{1}{4}}_{cs}\leq 10^6 \ km$ (or even better) could in principle be obtained, which will be at least 2 orders of magnitude stronger than the current one based on the observations from the GP-B mission and the LAGEOS I, II satellites. |
1001.0460 | Mayeul Arminjon | Mayeul Arminjon and Frank Reifler | Non-uniqueness of the Dirac theory in a curved spacetime | 13 pages (standard 12pt article format). Text of a talk given at the
1st Mediterranean Conference on Classical and Quantum Gravity, Kolymbari
(Greece), Sept. 14-18, 2009 | J.Phys.Conf.Ser. 222:012042,2010 | 10.1088/1742-6596/222/1/012042 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We summarize a recent work on the subject title. The Dirac equation in a
curved spacetime depends on a field of coefficients (essentially the Dirac
matrices), for which a continuum of different choices are possible. We study
the conditions under which a change of the coefficient fields leads to an
equivalent Hamiltonian operator H, or to an equivalent energy operator E. In
this paper, we focus on the standard version of the gravitational Dirac
equation, but the non-uniqueness applies also to our alternative versions. We
find that the changes which lead to an equivalent operator H, or respectively
to an equivalent operator E, are determined by initial data, or respectively
have to make some point-dependent antihermitian matrix vanish. Thus, the vast
majority of the possible coefficient changes lead neither to an equivalent
operator H, nor to an equivalent operator E, whence a lack of uniqueness. We
show that even the Dirac energy spectrum is not unique.
| [
{
"created": "Mon, 4 Jan 2010 08:54:30 GMT",
"version": "v1"
}
] | 2014-11-20 | [
[
"Arminjon",
"Mayeul",
""
],
[
"Reifler",
"Frank",
""
]
] | We summarize a recent work on the subject title. The Dirac equation in a curved spacetime depends on a field of coefficients (essentially the Dirac matrices), for which a continuum of different choices are possible. We study the conditions under which a change of the coefficient fields leads to an equivalent Hamiltonian operator H, or to an equivalent energy operator E. In this paper, we focus on the standard version of the gravitational Dirac equation, but the non-uniqueness applies also to our alternative versions. We find that the changes which lead to an equivalent operator H, or respectively to an equivalent operator E, are determined by initial data, or respectively have to make some point-dependent antihermitian matrix vanish. Thus, the vast majority of the possible coefficient changes lead neither to an equivalent operator H, nor to an equivalent operator E, whence a lack of uniqueness. We show that even the Dirac energy spectrum is not unique. |
2307.00318 | Mariem Magdy Ali Mohamed | Mariem Magdy Ali Mohamed | Calculation of asymptotic charges at the critical sets of null infinity | 16 pages, 2 Figures (A major change in the structure and content
compared to earlier version. The changes are made to agree with the peer
reviewed version.) | null | 10.1098/rsta.2023.0038 | null | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | The asymptotic structure of null and spatial infinities of asymptotically
flat spacetimes plays an essential role in discussing gravitational radiation,
gravitational memory effect, and conserved quantities in General Relativity.
Bondi, Metzner and Sachs established that the asymptotic symmetry group for
asymptotically simple spacetimes is the infinite-dimensional BMS group. Given
that null infinity is divided into two sets: past null infinity
$\mathscr{I}^{-}$ and future null infinity $\mathscr{I}^{+}$, one can identify
two independent symmetry groups: $\text{BMS}^{-}$ at $\mathscr{I}^{-}$ and
$\text{BMS}^{+}$ at $\mathscr{I}^{+}$. Associated with these symmetries are the
so-called BMS charges. A recent conjecture by Strominger suggests that the
generators of $\text{BMS}^{-}$ and $\text{BMS}^{+}$ and their associated
charges are related via an antipodal reflection map near spatial infinity. To
verify this matching, an analysis of the gravitational field near spatial
infinity is required. This task is complicated due to the singular nature of
spatial infinity for spacetimes with non-vanishing ADM mass. Different
frameworks have been introduced in the literature to address this singularity,
e.g., Friedrich's cylinder, Ashtekar-Hansen's hyperboloid and Ashtekar-Romano's
asymptote at spatial infinity. This paper reviews the role of Friedrich's
formulation of spatial infinity in the investigation of the matching of the
spin-2 charges on Minkowski spacetime and in the full GR setting.
| [
{
"created": "Sat, 1 Jul 2023 12:07:22 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Nov 2023 18:04:13 GMT",
"version": "v2"
}
] | 2024-01-17 | [
[
"Mohamed",
"Mariem Magdy Ali",
""
]
] | The asymptotic structure of null and spatial infinities of asymptotically flat spacetimes plays an essential role in discussing gravitational radiation, gravitational memory effect, and conserved quantities in General Relativity. Bondi, Metzner and Sachs established that the asymptotic symmetry group for asymptotically simple spacetimes is the infinite-dimensional BMS group. Given that null infinity is divided into two sets: past null infinity $\mathscr{I}^{-}$ and future null infinity $\mathscr{I}^{+}$, one can identify two independent symmetry groups: $\text{BMS}^{-}$ at $\mathscr{I}^{-}$ and $\text{BMS}^{+}$ at $\mathscr{I}^{+}$. Associated with these symmetries are the so-called BMS charges. A recent conjecture by Strominger suggests that the generators of $\text{BMS}^{-}$ and $\text{BMS}^{+}$ and their associated charges are related via an antipodal reflection map near spatial infinity. To verify this matching, an analysis of the gravitational field near spatial infinity is required. This task is complicated due to the singular nature of spatial infinity for spacetimes with non-vanishing ADM mass. Different frameworks have been introduced in the literature to address this singularity, e.g., Friedrich's cylinder, Ashtekar-Hansen's hyperboloid and Ashtekar-Romano's asymptote at spatial infinity. This paper reviews the role of Friedrich's formulation of spatial infinity in the investigation of the matching of the spin-2 charges on Minkowski spacetime and in the full GR setting. |
1811.08176 | Florencia Anabella Teppa Pannia | F.A. Teppa Pannia, S.E. Perez Bergliaffa, and N. Manske | Cosmography and the redshift drift in Palatini $f({\cal R})$ theories | 7 pages, 2 figures | Eur. Phys. J. C (2019) 79: 267 | 10.1140/epjc/s10052-019-6764-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an application to cosmological models in $f({\cal R})$ theories
within the Palatini formalism of a method that combines cosmography and the
explicit form of the field equations in the calculation of the redshift drift.
The method yields a sequence of constraint equations which lead to limits on
the parameter space of a given $f({\cal R})$-model. Two particular families of
$f({\cal R})$-cosmologies capable of describing the current dynamics of the
universe are explored here: (i) power law theories of the type $f({\cal
R})={\cal R}-\beta /{\cal R}^n$, and (ii) theories of the form $f({\cal
R})={\cal R}+\alpha \ln{{\cal R}} -\beta$. The constraints on $(n,\beta)$ and
$(\alpha,\beta)$, respectively, limit the values to intervals that are narrower
than the ones previously obtained. As a byproduct, we show that when applied to
General Relativity, the method yields values of the kinematic parameters with
much smaller errors that those obtained directly from observations.
| [
{
"created": "Tue, 20 Nov 2018 11:02:04 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Mar 2019 13:18:18 GMT",
"version": "v2"
}
] | 2019-03-28 | [
[
"Pannia",
"F. A. Teppa",
""
],
[
"Bergliaffa",
"S. E. Perez",
""
],
[
"Manske",
"N.",
""
]
] | We present an application to cosmological models in $f({\cal R})$ theories within the Palatini formalism of a method that combines cosmography and the explicit form of the field equations in the calculation of the redshift drift. The method yields a sequence of constraint equations which lead to limits on the parameter space of a given $f({\cal R})$-model. Two particular families of $f({\cal R})$-cosmologies capable of describing the current dynamics of the universe are explored here: (i) power law theories of the type $f({\cal R})={\cal R}-\beta /{\cal R}^n$, and (ii) theories of the form $f({\cal R})={\cal R}+\alpha \ln{{\cal R}} -\beta$. The constraints on $(n,\beta)$ and $(\alpha,\beta)$, respectively, limit the values to intervals that are narrower than the ones previously obtained. As a byproduct, we show that when applied to General Relativity, the method yields values of the kinematic parameters with much smaller errors that those obtained directly from observations. |
2205.12045 | Fengge Zhang | Fengge Zhang, Jia-Xi Feng and Xian Gao | Circularly polarized scalar induced gravitational waves from the
Chern-Simons modified gravity | 26 pages, 3 figures, references added, minor corrections | JCAP 10(2022)054 | 10.1088/1475-7516/2022/10/054 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the scalar induced gravitational waves (SIGWs) in the
Chern-Simons (CS) modified gravity during the radiation dominated era. The
SIGWs are circularly polarized, which provide us a tool to test the possible
parity violation in the early universe. We derive the semianalytic expressions
to evaluate the fractional energy density of the SIGWs, $\Omega_{\mathrm{GW}}$,
which receives contributions from the general relativity (GR) and the
correction due to the parity-violating term, respectively. We find that the
degree of the circular polarization of the SIGWs can be as large as of order
unity, although the contribution to $\Omega_{\mathrm{GW}}$ from the CS term is
at most of the same order as that from the GR.
| [
{
"created": "Tue, 24 May 2022 12:55:55 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Oct 2022 10:13:47 GMT",
"version": "v2"
}
] | 2022-10-19 | [
[
"Zhang",
"Fengge",
""
],
[
"Feng",
"Jia-Xi",
""
],
[
"Gao",
"Xian",
""
]
] | We investigate the scalar induced gravitational waves (SIGWs) in the Chern-Simons (CS) modified gravity during the radiation dominated era. The SIGWs are circularly polarized, which provide us a tool to test the possible parity violation in the early universe. We derive the semianalytic expressions to evaluate the fractional energy density of the SIGWs, $\Omega_{\mathrm{GW}}$, which receives contributions from the general relativity (GR) and the correction due to the parity-violating term, respectively. We find that the degree of the circular polarization of the SIGWs can be as large as of order unity, although the contribution to $\Omega_{\mathrm{GW}}$ from the CS term is at most of the same order as that from the GR. |
1006.2887 | Subenoy Chakraborty | Nairwita Mazumder, Ritabrata Biswas, Subenoy Chakraborty | Interacting Three Fluid System and Thermodynamics of the Universe
Bounded by the Event Horizon | 7 pages | Gen.Rel.Grav.43:1337-1345,2011 | 10.1007/s10714-010-1116-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The work deals with the thermodynamics of the universe bounded by the event
horizon. The matter in the universe has three constituents namely dark energy,
dark matter and radiation in nature and interaction between then is assumed.
The variation of entropy of the surface of the horizon is obtained from unified
first law while matter entropy variation is calculated from the Gibbss' law.
Finally, validity of the generalized second law of thermodynamics is examined
and conclusions are written point wise.
| [
{
"created": "Tue, 15 Jun 2010 04:38:51 GMT",
"version": "v1"
}
] | 2011-04-22 | [
[
"Mazumder",
"Nairwita",
""
],
[
"Biswas",
"Ritabrata",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | The work deals with the thermodynamics of the universe bounded by the event horizon. The matter in the universe has three constituents namely dark energy, dark matter and radiation in nature and interaction between then is assumed. The variation of entropy of the surface of the horizon is obtained from unified first law while matter entropy variation is calculated from the Gibbss' law. Finally, validity of the generalized second law of thermodynamics is examined and conclusions are written point wise. |
1209.4099 | G\"ul\c{c}in Berkoz Uluyazi | G\"ul\c{c}in Uluyazi | An Investigation of Equivalence between the Bulk-based and the
Brane-based Approaches for Anisotropic Models | 8 pages | Gen. Rel. and Grav. V. 44, Number 4 (2012), 875-886 | 10.1007/s10714-011-1313-4 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the relation between the brane-based and the bulk-based
approaches for anisotropic case in brane-world models. In the brane-based
approach, the brane is chosen to be fixed on a coordinate system, whereas in
the bulk-based approach it is no longer static as it moves along the extra
dimension. It was shown that these two approaches are basicly equal for
specific models Mukohyama et al., Bowcock et al. In this paper, it is aimed to
get general formalism of the equivalence obtained in Mukohyama et al. We found
that calculations driven by a general anisotropic bulk-based metric yield a
brane-based metric in Gaussian Normal Coordinates by conserving spatial
anisotropy. We also derive solutions for an anisotropic bulk-based model and
apply to get corresponding brane-based metric of the model.
| [
{
"created": "Tue, 18 Sep 2012 20:28:58 GMT",
"version": "v1"
}
] | 2012-09-20 | [
[
"Uluyazi",
"Gülçin",
""
]
] | We investigate the relation between the brane-based and the bulk-based approaches for anisotropic case in brane-world models. In the brane-based approach, the brane is chosen to be fixed on a coordinate system, whereas in the bulk-based approach it is no longer static as it moves along the extra dimension. It was shown that these two approaches are basicly equal for specific models Mukohyama et al., Bowcock et al. In this paper, it is aimed to get general formalism of the equivalence obtained in Mukohyama et al. We found that calculations driven by a general anisotropic bulk-based metric yield a brane-based metric in Gaussian Normal Coordinates by conserving spatial anisotropy. We also derive solutions for an anisotropic bulk-based model and apply to get corresponding brane-based metric of the model. |
gr-qc/9303029 | Mail | M. Carfora, A. Marzuoli | Critical Phenomena for Riemannian Manifolds: Simple Homotopy and
Simplicial Quantum Gravity | 78 pages, latex | null | null | FNT/T 90/19 | gr-qc | null | We show how Gromov's spaces of bounded geometries provide a general
mathematical framework for addressing and solving many of the issues of
$3D$-simplicial quantum gravity. In particular, we establish entropy estimates
characterizing the asymptotic distribution of combinatorially inequivalent
triangulated $3$-manifolds, as the number of tetrahedra diverges. Moreover, we
offer a rather detailed presentation of how spaces of three-dimensional
riemannian manifolds with natural bounds on curvatures, diameter, and volume
can be used to prove that three-dimensional simplicial quantum gravity is
connected to a Gaussian model determined by the simple homotopy types of the
underlying manifolds. This connection is determined by a Gaussian measure
defined over the general linear group $GL({\bf R},\infty)$. It is shown that
the partition function of three-dimensional simplicial quantum gravity is
well-defined, in the thermodynamic limit, for a suitable range of values of the
gravitational and cosmological coupling constants. Such values are determined
by the Reidemeister-Franz torsion invariants associated with an orthogonal
representation of the fundamental groups of the set of manifolds considered.
The geometrical system considered shows also critical behavior, and in such a
case the partition function is exactly evaluated and shown to be equal to the
Reidemeister-Franz torsion. The phase structure in the thermodynamical limit is
also discussed. In particular, there are either phase transitions describing
the passage from a simple homotopy type to another, and (first order) phase
transitions within a given simple homotopy type which seem to confirm, on an
analytical ground, the picture suggested by numerical simulations.
| [
{
"created": "Fri, 26 Mar 1993 12:56:33 GMT",
"version": "v1"
}
] | 2007-08-09 | [
[
"Carfora",
"M.",
""
],
[
"Marzuoli",
"A.",
""
]
] | We show how Gromov's spaces of bounded geometries provide a general mathematical framework for addressing and solving many of the issues of $3D$-simplicial quantum gravity. In particular, we establish entropy estimates characterizing the asymptotic distribution of combinatorially inequivalent triangulated $3$-manifolds, as the number of tetrahedra diverges. Moreover, we offer a rather detailed presentation of how spaces of three-dimensional riemannian manifolds with natural bounds on curvatures, diameter, and volume can be used to prove that three-dimensional simplicial quantum gravity is connected to a Gaussian model determined by the simple homotopy types of the underlying manifolds. This connection is determined by a Gaussian measure defined over the general linear group $GL({\bf R},\infty)$. It is shown that the partition function of three-dimensional simplicial quantum gravity is well-defined, in the thermodynamic limit, for a suitable range of values of the gravitational and cosmological coupling constants. Such values are determined by the Reidemeister-Franz torsion invariants associated with an orthogonal representation of the fundamental groups of the set of manifolds considered. The geometrical system considered shows also critical behavior, and in such a case the partition function is exactly evaluated and shown to be equal to the Reidemeister-Franz torsion. The phase structure in the thermodynamical limit is also discussed. In particular, there are either phase transitions describing the passage from a simple homotopy type to another, and (first order) phase transitions within a given simple homotopy type which seem to confirm, on an analytical ground, the picture suggested by numerical simulations. |
1010.1855 | Bijan Saha Dr. | Bijan Saha | Bianchi type-II cosmological model: some remarks | 3 pages | Central Eur.J.Phys.9 (2011) 939 - 941 | 10.2478/s11534-011-0017-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Within the framework of Bianchi type-II (BII) cosmological model the behavior
of matter distribution has been considered. It is shown that the non-zero
off-diagonal component of Einstein tensor implies some severe restriction on
the choice of matter distribution. In particular for a locally rotationally
symmetric Bianchi type-II (LRS BII) space-time it is proved that the matter
distribution should be strictly isotropic if the corresponding matter field
possesses only non-zero diagonal components of the energy-momentum tensor.
| [
{
"created": "Sat, 9 Oct 2010 16:03:52 GMT",
"version": "v1"
}
] | 2015-05-01 | [
[
"Saha",
"Bijan",
""
]
] | Within the framework of Bianchi type-II (BII) cosmological model the behavior of matter distribution has been considered. It is shown that the non-zero off-diagonal component of Einstein tensor implies some severe restriction on the choice of matter distribution. In particular for a locally rotationally symmetric Bianchi type-II (LRS BII) space-time it is proved that the matter distribution should be strictly isotropic if the corresponding matter field possesses only non-zero diagonal components of the energy-momentum tensor. |
gr-qc/9709084 | Lars Andersson | L. Andersson, G. J. Galloway and R. Howard | The Cosmological Time Function | 19 pages, AEI preprint, latex2e with amsmath and amsthm | Class.Quant.Grav. 15 (1998) 309-322 | 10.1088/0264-9381/15/2/006 | null | gr-qc dg-ga math.DG | null | Let $(M,g)$ be a time oriented Lorentzian manifold and $d$ the Lorentzian
distance on $M$. The function $\tau(q):=\sup_{p< q} d(p,q)$ is the cosmological
time function of $M$, where as usual $p< q$ means that $p$ is in the causal
past of $q$. This function is called regular iff $\tau(q) < \infty$ for all $q$
and also $\tau \to 0$ along every past inextendible causal curve. If the
cosmological time function $\tau$ of a space time $(M,g)$ is regular it has
several pleasant consequences: (1) It forces $(M,g)$ to be globally hyperbolic,
(2) every point of $(M,g)$ can be connected to the initial singularity by a
rest curve (i.e., a timelike geodesic ray that maximizes the distance to the
singularity), (3) the function $\tau$ is a time function in the usual sense, in
particular (4) $\tau$ is continuous, in fact locally Lipschitz and the second
derivatives of $\tau$ exist almost everywhere.
| [
{
"created": "Tue, 30 Sep 1997 20:04:38 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Andersson",
"L.",
""
],
[
"Galloway",
"G. J.",
""
],
[
"Howard",
"R.",
""
]
] | Let $(M,g)$ be a time oriented Lorentzian manifold and $d$ the Lorentzian distance on $M$. The function $\tau(q):=\sup_{p< q} d(p,q)$ is the cosmological time function of $M$, where as usual $p< q$ means that $p$ is in the causal past of $q$. This function is called regular iff $\tau(q) < \infty$ for all $q$ and also $\tau \to 0$ along every past inextendible causal curve. If the cosmological time function $\tau$ of a space time $(M,g)$ is regular it has several pleasant consequences: (1) It forces $(M,g)$ to be globally hyperbolic, (2) every point of $(M,g)$ can be connected to the initial singularity by a rest curve (i.e., a timelike geodesic ray that maximizes the distance to the singularity), (3) the function $\tau$ is a time function in the usual sense, in particular (4) $\tau$ is continuous, in fact locally Lipschitz and the second derivatives of $\tau$ exist almost everywhere. |
2005.06955 | Muhammad Zubair | M. Zubair, Hina Azmat | Anisotropic Tolman V Solution by Minimal Gravitational Decoupling
Approach | 11 pages, 4 figures | Annals of Physics, Volume 420, 168248 (2020) | 10.1016/j.aop.2020.168248 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider well known Tolman V perfect fluid solution and
extend it to its an anisotropic version using gravitational decoupling by
minimal geometric deformation approach and analyze the behavior of new version
of the solution graphically. The effects of coupling constant on anisotropic
factor has been measured and presented graphically. The matching conditions at
the surface of inner and outer geometry have also been discussed. The viability
of the solution has been studied by presenting the physical analysis of the
solution.
| [
{
"created": "Thu, 23 Apr 2020 04:45:49 GMT",
"version": "v1"
}
] | 2020-09-29 | [
[
"Zubair",
"M.",
""
],
[
"Azmat",
"Hina",
""
]
] | In this paper, we consider well known Tolman V perfect fluid solution and extend it to its an anisotropic version using gravitational decoupling by minimal geometric deformation approach and analyze the behavior of new version of the solution graphically. The effects of coupling constant on anisotropic factor has been measured and presented graphically. The matching conditions at the surface of inner and outer geometry have also been discussed. The viability of the solution has been studied by presenting the physical analysis of the solution. |
1511.06249 | Gerard Clement | G\'erard Cl\'ement | Axisymmetric multiwormholes revisited | 12 pages | Gen. Relat. Grav. 48 (2016) 76 | 10.1007/s10714-016-2073-y | LAPTH-063/15 | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The construction of stationary axisymmetric multiwormhole solutions to
gravitating field theories admitting toroidal reductions to three-dimensional
gravitating sigma models is reviewed. We show that, as in the multi-black hole
case, strut singularities always appear in this construction, except for very
special configurations with an odd number of centers. We also review the
analytical continuation of the multicenter solution across the $n$ cuts
associated with the wormhole mouths. The resulting Riemann manifold has $2^n$
sheets interconnected by $2^{n-1}n$ wormholes. We find that the maximally
extended multicenter solution can never be asymptotically locally flat in all
the Riemann sheets.
| [
{
"created": "Thu, 19 Nov 2015 16:47:29 GMT",
"version": "v1"
},
{
"created": "Sun, 6 Dec 2015 09:33:48 GMT",
"version": "v2"
}
] | 2021-03-01 | [
[
"Clément",
"Gérard",
""
]
] | The construction of stationary axisymmetric multiwormhole solutions to gravitating field theories admitting toroidal reductions to three-dimensional gravitating sigma models is reviewed. We show that, as in the multi-black hole case, strut singularities always appear in this construction, except for very special configurations with an odd number of centers. We also review the analytical continuation of the multicenter solution across the $n$ cuts associated with the wormhole mouths. The resulting Riemann manifold has $2^n$ sheets interconnected by $2^{n-1}n$ wormholes. We find that the maximally extended multicenter solution can never be asymptotically locally flat in all the Riemann sheets. |
2001.03014 | Dr. Goutam Manna | Bivash Majumder, Goutam Manna and Ashoke Das | Time-like geodesic structure for the K-essence Emergent
Barriola-Vilenkin type spacetime | 11 pages, 3 figures, Accepted from Classical and Quantum Gravity
(CQG) | null | 10.1088/1361-6382/ab86fa | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | For a particular type of {\bf k-}essence scalar field, the {\bf k-}essence
emergent gravity metric is exactly mapped on to the Barriola-Vilenkin (BV) type
metric for Schwarzschild background established by Gangopadhyay and Manna.
Based on the S. Chandrasekhar, we report the exciting features of the time-like
geodesic structure in the presence of dark energy in an emergent gravity
scenario for this Barriola-Vilenkin type metric. We trace the different kinds
of trajectories for time-like geodesic in the presence of dark energy for the
{\bf k-}essence emergent Barriola-Vilenkin spacetime, which is same as the
Schwarzchild spacetime in view of the basic orientation, but the allowed ranges
of the aphelion and perihelion distances are much more different. The bound and
unbound orbits are plotted for a fixed value of the dark energy density.
| [
{
"created": "Wed, 8 Jan 2020 18:04:57 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Jan 2020 17:14:04 GMT",
"version": "v2"
},
{
"created": "Tue, 7 Apr 2020 13:51:11 GMT",
"version": "v3"
}
] | 2020-04-08 | [
[
"Majumder",
"Bivash",
""
],
[
"Manna",
"Goutam",
""
],
[
"Das",
"Ashoke",
""
]
] | For a particular type of {\bf k-}essence scalar field, the {\bf k-}essence emergent gravity metric is exactly mapped on to the Barriola-Vilenkin (BV) type metric for Schwarzschild background established by Gangopadhyay and Manna. Based on the S. Chandrasekhar, we report the exciting features of the time-like geodesic structure in the presence of dark energy in an emergent gravity scenario for this Barriola-Vilenkin type metric. We trace the different kinds of trajectories for time-like geodesic in the presence of dark energy for the {\bf k-}essence emergent Barriola-Vilenkin spacetime, which is same as the Schwarzchild spacetime in view of the basic orientation, but the allowed ranges of the aphelion and perihelion distances are much more different. The bound and unbound orbits are plotted for a fixed value of the dark energy density. |
2202.11791 | George E. A. Matsas Professor | Luanna K. de Souza and George E. A. Matsas | Black-hole analog in vehicular traffic | 14 pages, 5 figures | Am. J. Phys., vol. 90, p. 692 (2022) | 10.1119/5.0091957 | null | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | We propose here a simple black-hole analog in vehicular-traffic dynamics. The
corresponding causal diagram is determined by the propagation of the tail light
flashes emitted by a convoy of cars on a highway. In addition to being a new
black-hole analog, this illustrates how causal diagrams, so common in general
relativity, may be useful in areas as unexpected as vehicular-traffic dynamics.
| [
{
"created": "Wed, 23 Feb 2022 21:18:32 GMT",
"version": "v1"
},
{
"created": "Sun, 24 Jul 2022 20:57:25 GMT",
"version": "v2"
},
{
"created": "Thu, 25 Aug 2022 13:56:09 GMT",
"version": "v3"
}
] | 2022-08-26 | [
[
"de Souza",
"Luanna K.",
""
],
[
"Matsas",
"George E. A.",
""
]
] | We propose here a simple black-hole analog in vehicular-traffic dynamics. The corresponding causal diagram is determined by the propagation of the tail light flashes emitted by a convoy of cars on a highway. In addition to being a new black-hole analog, this illustrates how causal diagrams, so common in general relativity, may be useful in areas as unexpected as vehicular-traffic dynamics. |
2203.06447 | Qihong Huang | Qihong Huang, Kaituo Zhang, Zhenxing Fang and Feiquan Tu | Analytical approximations for primordial power spectra in a spatially
closed emergent universe | null | Physics of the Dark Universe 38 (2022) 101124 | 10.1016/j.dark.2022.101124 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The emergent universe scenario was proposed to solve the big bang singularity
by suggesting that the universe originates from an Einstein static state and
then evolves into a subsequently inflationary era. Thus, to find the relic of
the existence of the Einstein static state becomes a crucial work. In this
paper, we derive analytical approximation of the primordial power spectra and
analyze the CMB TT-spectra for the spatially closed emergent universe. After
analyzing the CMB TT-spectrum of the emergent universe scenario, we find that
both the CMB TT-spectra produced by the Einstein static state followed by the
ultraslow-roll inflationary epoch (method I) and by a special evolution of the
scale factor in the emergent scenario as $a=a_{0}+A e^{H_{0}t}$(method II) are
suppressed at $l<30$, and their spectra are nearly identical. Additionally, by
comparing the spectra of the emergent universe scenario with the ones of the
ultraslow-roll inflationary model in the closed universe, we find that the CMB
TT-spectrum of the emergent universe is similar to the one of the inflationary
model with the special case $\eta_t = \eta_{max}$.
| [
{
"created": "Sat, 12 Mar 2022 14:40:02 GMT",
"version": "v1"
},
{
"created": "Sun, 30 Oct 2022 13:10:23 GMT",
"version": "v2"
}
] | 2022-11-01 | [
[
"Huang",
"Qihong",
""
],
[
"Zhang",
"Kaituo",
""
],
[
"Fang",
"Zhenxing",
""
],
[
"Tu",
"Feiquan",
""
]
] | The emergent universe scenario was proposed to solve the big bang singularity by suggesting that the universe originates from an Einstein static state and then evolves into a subsequently inflationary era. Thus, to find the relic of the existence of the Einstein static state becomes a crucial work. In this paper, we derive analytical approximation of the primordial power spectra and analyze the CMB TT-spectra for the spatially closed emergent universe. After analyzing the CMB TT-spectrum of the emergent universe scenario, we find that both the CMB TT-spectra produced by the Einstein static state followed by the ultraslow-roll inflationary epoch (method I) and by a special evolution of the scale factor in the emergent scenario as $a=a_{0}+A e^{H_{0}t}$(method II) are suppressed at $l<30$, and their spectra are nearly identical. Additionally, by comparing the spectra of the emergent universe scenario with the ones of the ultraslow-roll inflationary model in the closed universe, we find that the CMB TT-spectrum of the emergent universe is similar to the one of the inflationary model with the special case $\eta_t = \eta_{max}$. |
2404.19046 | Christos Tsagas | Eleftheria P. Miliou, Christos G. Tsagas | Peculiar velocities in Friedmann universes with nonzero spatial
curvature | 15 pages, 1 figure | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend the earlier linear studies of cosmological peculiar velocities to
Friedmann universes with nonzero spatial curvature. In the process, we also
compare our results with those obtained in cosmologies with Euclidean spatial
sections. Employing relativistic cosmological perturbation theory, we first
provide the differential formulae governing the evolution of peculiar
velocities on all Friedmann backgrounds. The technical complexities of the
curved models, however, mean that analytic solutions are possible only in
special, though characteristic, moments in the lifetime of these universes.
Nevertheless, our solutions exhibit persistent patterns that make us confident
enough to generalise them. Thus, we confirm earlier claims that, compared to
the Newtonian studies, the relativistic analysis supports considerably stronger
linear growth-rates for peculiar-velocity perturbations. This result holds
irrespective of the background curvature. Moreover, for positive curvature, the
peculiar growth-rate is found to be faster than that obtained in a spatially
flat Friedman universe. In contrast, linear peculiar velocities appear to grow
at a slower pace when their Friedmann host is spatially open. Extrapolating
them to the present, our results seem to suggest faster bulk peculiar motions
in overdense, rather than in underdense, regions of the universe.
| [
{
"created": "Mon, 29 Apr 2024 18:35:52 GMT",
"version": "v1"
}
] | 2024-05-01 | [
[
"Miliou",
"Eleftheria P.",
""
],
[
"Tsagas",
"Christos G.",
""
]
] | We extend the earlier linear studies of cosmological peculiar velocities to Friedmann universes with nonzero spatial curvature. In the process, we also compare our results with those obtained in cosmologies with Euclidean spatial sections. Employing relativistic cosmological perturbation theory, we first provide the differential formulae governing the evolution of peculiar velocities on all Friedmann backgrounds. The technical complexities of the curved models, however, mean that analytic solutions are possible only in special, though characteristic, moments in the lifetime of these universes. Nevertheless, our solutions exhibit persistent patterns that make us confident enough to generalise them. Thus, we confirm earlier claims that, compared to the Newtonian studies, the relativistic analysis supports considerably stronger linear growth-rates for peculiar-velocity perturbations. This result holds irrespective of the background curvature. Moreover, for positive curvature, the peculiar growth-rate is found to be faster than that obtained in a spatially flat Friedman universe. In contrast, linear peculiar velocities appear to grow at a slower pace when their Friedmann host is spatially open. Extrapolating them to the present, our results seem to suggest faster bulk peculiar motions in overdense, rather than in underdense, regions of the universe. |
gr-qc/0405109 | Charles W. Misner | R. Arnowitt (Syracuse Univ.), S. Deser (Brandeis Univ.) and C. W.
Misner (Princeton Univ.) | The Dynamics of General Relativity | 30 pages (LaTeX2e), uses amsfonts, no figures | "Gravitation: an introduction to current research", Louis Witten
ed. (Wiley 1962), chapter 7, pp 227--265 | 10.1007/s10714-008-0661-1 | null | gr-qc astro-ph hep-th | null | This article--summarizing the authors' then novel formulation of General
Relativity--appeared as Chapter 7 of an often cited compendium edited by L.
Witten in 1962, which is now long out of print. Intentionally unretouched, this
posting is intended to provide contemporary accessibility to the flavor of the
original ideas. Some typographical corrections have been made: footnote and
page numbering have changed--but not section nor equation numbering etc. The
authors' current institutional affiliations are encoded in:
arnowitt@physics.tamu.edu, deser@brandeis.edu, misner@physics.umd.edu .
| [
{
"created": "Wed, 19 May 2004 17:49:35 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Arnowitt",
"R.",
"",
"Syracuse Univ."
],
[
"Deser",
"S.",
"",
"Brandeis Univ."
],
[
"Misner",
"C. W.",
"",
"Princeton Univ."
]
] | This article--summarizing the authors' then novel formulation of General Relativity--appeared as Chapter 7 of an often cited compendium edited by L. Witten in 1962, which is now long out of print. Intentionally unretouched, this posting is intended to provide contemporary accessibility to the flavor of the original ideas. Some typographical corrections have been made: footnote and page numbering have changed--but not section nor equation numbering etc. The authors' current institutional affiliations are encoded in: arnowitt@physics.tamu.edu, deser@brandeis.edu, misner@physics.umd.edu . |
1711.01313 | Thomas Zannias | Thomas Zannias | On causality violation on a Kerr-de Sitter spacetime | 20 pages, 3 figures | Gen.Rel.Grav. 50, 134, (2018) | 10.1007/s10714-018-2456-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The causal properties of the family of Kerr-de Sitter spacetimes are analyzed
and compared to those of the Kerr family. At first we show that a Kerr-de
Sitter spacetime can be viewed as an assembly of Carter's blocks i.e. four
dimensional spacetime regions contained within Killing horizons or a Killing
horizon and the asymptotic de Sitter region. From this perspective and leaving
aside topological identifications, the causal properties of a Kerr de Sitter
spacetime are determined by the causal properties of the individual Carter's
blocks viewed as spacetimes in their own right. We show that any Carter's block
is stably causal except for the blocks that contain the ring singularity. The
latter are vicious sets: any two events within such block can be connected by a
future (respectively past) directed timelike curve. This behavior is identical
to the causal behavior of the Boyer-Lindquist blocks that contains the Kerr
ring singularity which are also vicious sets. On the other hand, while for the
case of a naked Kerr singularity the entire spacetime is a vicious set and thus
closed timelike curves pass through any event including events lying in the
asymptotic region, for the case of a Kerr-de Sitter spacetime the cosmological
horizons imply that the asymptotic de Sitter region is causally well behaved.
In that regard a positive cosmological constant appears to improve the causal
behavior of the underlying spacetime.
| [
{
"created": "Fri, 3 Nov 2017 19:38:25 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Dec 2018 20:24:27 GMT",
"version": "v2"
}
] | 2018-12-27 | [
[
"Zannias",
"Thomas",
""
]
] | The causal properties of the family of Kerr-de Sitter spacetimes are analyzed and compared to those of the Kerr family. At first we show that a Kerr-de Sitter spacetime can be viewed as an assembly of Carter's blocks i.e. four dimensional spacetime regions contained within Killing horizons or a Killing horizon and the asymptotic de Sitter region. From this perspective and leaving aside topological identifications, the causal properties of a Kerr de Sitter spacetime are determined by the causal properties of the individual Carter's blocks viewed as spacetimes in their own right. We show that any Carter's block is stably causal except for the blocks that contain the ring singularity. The latter are vicious sets: any two events within such block can be connected by a future (respectively past) directed timelike curve. This behavior is identical to the causal behavior of the Boyer-Lindquist blocks that contains the Kerr ring singularity which are also vicious sets. On the other hand, while for the case of a naked Kerr singularity the entire spacetime is a vicious set and thus closed timelike curves pass through any event including events lying in the asymptotic region, for the case of a Kerr-de Sitter spacetime the cosmological horizons imply that the asymptotic de Sitter region is causally well behaved. In that regard a positive cosmological constant appears to improve the causal behavior of the underlying spacetime. |
2006.14747 | El\'ias Castellanos Dr. | Jasel Berra-Montiel, El\'ias Castellanos, Alberto Molgado and Jonathan
Trinidad-Garc\'ia | Superfluids in Polymer Quantum Mechanics | 14 pages | Modern Physics Letters A Vol. 36, No. 07, 2150045 (2021) | 10.1142/S0217732321500450 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we analyze the corrections obtained on a homogeneous
one-dimensional Bose gas within the high densities limit by means of the
polymer quantization scheme. Thus, starting from the Bogoliubov formalism, we
analyze the ground expectation value of the polymer momentum operator in terms
of semiclassical states, in order to obtain an analytic expression for the
ground state energy of the N-body system, which allows us to solve the
pathological behavior commonly associated with the one-dimensional
Bose-Einstein condensation through the introduction of finite size effects
characterized by the contribution of the polymer corrections. We also discuss
the speed of sound in our polymer version of the Bose gas and the corresponding
relative shift induced by the introduction of a minimum length parameter.
Finally, by considering the idea that the Bose-Einstein condensation phenomenon
is closely related to that of superfluidity, we investigate the emergent
superfluid behavior in our polymer model by implementing an appropriate
Landau's criterion. In this case, we are able to consequently analyze the
changes in the critical velocity which defines the limit between the
superfluid-condensate regions, thus deducing that the polymer length acts as a
kind of pseudo-potential which induces a dissipationless flow associated with
the superfluid phase even in the absence of self-interactions.
| [
{
"created": "Fri, 26 Jun 2020 01:31:29 GMT",
"version": "v1"
}
] | 2021-03-12 | [
[
"Berra-Montiel",
"Jasel",
""
],
[
"Castellanos",
"Elías",
""
],
[
"Molgado",
"Alberto",
""
],
[
"Trinidad-García",
"Jonathan",
""
]
] | In this work, we analyze the corrections obtained on a homogeneous one-dimensional Bose gas within the high densities limit by means of the polymer quantization scheme. Thus, starting from the Bogoliubov formalism, we analyze the ground expectation value of the polymer momentum operator in terms of semiclassical states, in order to obtain an analytic expression for the ground state energy of the N-body system, which allows us to solve the pathological behavior commonly associated with the one-dimensional Bose-Einstein condensation through the introduction of finite size effects characterized by the contribution of the polymer corrections. We also discuss the speed of sound in our polymer version of the Bose gas and the corresponding relative shift induced by the introduction of a minimum length parameter. Finally, by considering the idea that the Bose-Einstein condensation phenomenon is closely related to that of superfluidity, we investigate the emergent superfluid behavior in our polymer model by implementing an appropriate Landau's criterion. In this case, we are able to consequently analyze the changes in the critical velocity which defines the limit between the superfluid-condensate regions, thus deducing that the polymer length acts as a kind of pseudo-potential which induces a dissipationless flow associated with the superfluid phase even in the absence of self-interactions. |
0707.1943 | Christian Corda cordac | Christian Corda | Analysis of the transverse effect of Einstein's gravitational waves | Review paper, accepted for the International Journal of Modern
Physics A | Int.J.Mod.Phys.A22:4859-4881,2007 | 10.1142/S0217751X07037172 | null | gr-qc | null | The investigation of the transverse effect of gravitational waves (GWs) could
constitute a further tool to discriminate among several relativistic theories
of gravity on the ground. After a review of the TT gauge, the transverse effect
of GWs arising by standard general relativity (called Einstein's GWs in this
paper) is reanalized with a different choice of coordinates. In the chosen
gauge test masses have an apparent motion in the direction of propagation of
the wave, while in the transverse direction they appear at rest. Of course,
this is only a gauge artefact. In fact, from careful investigation of this
particular gauge, it is shown that the tidal forces associated with GWs act
along the directions orthogonal to the direction of propagation of waves. In
the analysis it is also shown, in a heuristic way, that the transverse effect
of Einstein's GWs arises from the propagation of the waves at the speed of the
light, thus only massless GWs are purely transverse. But, because the physics
of gravitational waves has to be investigated by studing the tidal forces as
appearing in the geodesic deviation equation and directly in a laboratory
environment on Earth, an analysis of these tidal forces and of the transverse
effect in the frame of the local observer is also performed. After this, for a
further better understanding of the transverse effect, an example of a wave,
which arises from scalar tensor gravity, with both transverse and genuinely
longitudinal modes is given and discussed. In the example the connection
between the longitudinal component and the velocity of the wave will be
mathematical shown.
At the end of this paper the review of the TT gauge is completed, recovering
the gauge invariance between the presented gauge and the TT one.
| [
{
"created": "Fri, 13 Jul 2007 09:11:07 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Corda",
"Christian",
""
]
] | The investigation of the transverse effect of gravitational waves (GWs) could constitute a further tool to discriminate among several relativistic theories of gravity on the ground. After a review of the TT gauge, the transverse effect of GWs arising by standard general relativity (called Einstein's GWs in this paper) is reanalized with a different choice of coordinates. In the chosen gauge test masses have an apparent motion in the direction of propagation of the wave, while in the transverse direction they appear at rest. Of course, this is only a gauge artefact. In fact, from careful investigation of this particular gauge, it is shown that the tidal forces associated with GWs act along the directions orthogonal to the direction of propagation of waves. In the analysis it is also shown, in a heuristic way, that the transverse effect of Einstein's GWs arises from the propagation of the waves at the speed of the light, thus only massless GWs are purely transverse. But, because the physics of gravitational waves has to be investigated by studing the tidal forces as appearing in the geodesic deviation equation and directly in a laboratory environment on Earth, an analysis of these tidal forces and of the transverse effect in the frame of the local observer is also performed. After this, for a further better understanding of the transverse effect, an example of a wave, which arises from scalar tensor gravity, with both transverse and genuinely longitudinal modes is given and discussed. In the example the connection between the longitudinal component and the velocity of the wave will be mathematical shown. At the end of this paper the review of the TT gauge is completed, recovering the gauge invariance between the presented gauge and the TT one. |
1605.04293 | Javier Olmedo | Florencia Ben\'itez Mart\'inez and Javier Olmedo | Primordial tensor modes of the early Universe | 26 pages, minor corrections and typos, bibliography updated | Phys. Rev. D 93, 124008 (2016) | 10.1103/PhysRevD.93.124008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study cosmological tensor perturbations on a quantized background within
the hybrid quantization approach. In particular, we consider a flat,
homogeneous and isotropic spacetime and small tensor inhomogeneities on it. We
truncate the action to second order in the perturbations. The dynamics is ruled
by a homogeneous scalar constraint. We carry out a canonical transformation in
the system where the Hamiltonian for the tensor perturbations takes a canonical
form. The new tensor modes now admit a standard Fock quantization with a
unitary dynamics. We then combine this representation with a generic quantum
scheme for the homogeneous sector. We adopt a Born-Oppenheimer ansatz for the
solutions to the constraint operator, previously employed to study the dynamics
of scalar inhomogeneities. We analyze the approximations that allow us to
recover, on the one hand, a Schr\"odinger equation similar to the one emerging
in the dressed metric approach and, on the other hand, the ones necessary for
the effective evolution equations of these primordial tensor modes within the
hybrid approach to be valid. Finally, we consider loop quantum cosmology as an
example where these quantization techniques can be applied and compare with
other approaches.
| [
{
"created": "Fri, 13 May 2016 19:16:15 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Jun 2016 20:46:33 GMT",
"version": "v2"
}
] | 2016-06-07 | [
[
"Martínez",
"Florencia Benítez",
""
],
[
"Olmedo",
"Javier",
""
]
] | We study cosmological tensor perturbations on a quantized background within the hybrid quantization approach. In particular, we consider a flat, homogeneous and isotropic spacetime and small tensor inhomogeneities on it. We truncate the action to second order in the perturbations. The dynamics is ruled by a homogeneous scalar constraint. We carry out a canonical transformation in the system where the Hamiltonian for the tensor perturbations takes a canonical form. The new tensor modes now admit a standard Fock quantization with a unitary dynamics. We then combine this representation with a generic quantum scheme for the homogeneous sector. We adopt a Born-Oppenheimer ansatz for the solutions to the constraint operator, previously employed to study the dynamics of scalar inhomogeneities. We analyze the approximations that allow us to recover, on the one hand, a Schr\"odinger equation similar to the one emerging in the dressed metric approach and, on the other hand, the ones necessary for the effective evolution equations of these primordial tensor modes within the hybrid approach to be valid. Finally, we consider loop quantum cosmology as an example where these quantization techniques can be applied and compare with other approaches. |
1607.05998 | Muhammad Zubair | M. Zubair, Saira Waheed and Yasir Ahmad | Static Spherically Symmetric Wormholes in $f(R,T)$ Gravity | 26 pages, 12 figures | Eur. Phys. J. C (2016) 76:444 | 10.1140/epjc/s10052-016-4288-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we explore wormhole solutions in $f(R,T)$ theory of gravity,
where $R$ is the scalar curvature and $T$ is the trace of stress-energy tensor
of matter. To investigate this, we consider static spherically symmetric
geometry with matter contents as anisotropic, isotropic and barotropic fluids
in three separate cases. By taking into account Starobinsky $f(R)$ model , we
analyze the behavior of energy conditions for these different kind of fluids.
It is shown that the wormhole solutions can be constructed without exotic
matter in few regions of spacetime. We also give the graphical illustration of
obtained results and discuss the equilibrium picture for anisotropic case only.
It is concluded that the wormhole solutions with anisotropic matter are
realistic and stable in this gravity.
| [
{
"created": "Tue, 19 Jul 2016 12:36:13 GMT",
"version": "v1"
}
] | 2016-08-10 | [
[
"Zubair",
"M.",
""
],
[
"Waheed",
"Saira",
""
],
[
"Ahmad",
"Yasir",
""
]
] | In this work, we explore wormhole solutions in $f(R,T)$ theory of gravity, where $R$ is the scalar curvature and $T$ is the trace of stress-energy tensor of matter. To investigate this, we consider static spherically symmetric geometry with matter contents as anisotropic, isotropic and barotropic fluids in three separate cases. By taking into account Starobinsky $f(R)$ model , we analyze the behavior of energy conditions for these different kind of fluids. It is shown that the wormhole solutions can be constructed without exotic matter in few regions of spacetime. We also give the graphical illustration of obtained results and discuss the equilibrium picture for anisotropic case only. It is concluded that the wormhole solutions with anisotropic matter are realistic and stable in this gravity. |
1901.06388 | Ra\'ul Carballo-Rubio | Carlos Barcel\'o, Ra\'ul Carballo-Rubio and Stefano Liberati | Generalized no-hair theorems without horizons | v2: 18 pages, 1 figure, a couple of minor changes and typos fixed, as
accepted for publication; v1: 17 pages, 1 figure | Class.Quant.Grav. 36 (2019) no.13, 13LT01 | 10.1088/1361-6382/ab23b6 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The simplicity of black holes, as characterized by no-hair theorems, is one
of the most important mathematical results in the framework of general
relativity. Are these theorems unique to black hole spacetimes, or do they also
constrain the geometry around regions of spacetime with arbitrarily large
(although finite) redshift? This paper presents a systematic study of this
question and illustrates that no-hair theorems are not restricted to spacetimes
with event horizons but are instead characteristic of spacetimes with deep
enough gravitational wells, extending Israel's theorem to static spacetimes
without event horizons that contain small deviations from spherical symmetry.
Instead of a uniqueness result, we obtain a theorem that constrains the allowed
deviations from the Schwarzschild metric and guarantees that these deviations
decrease with the maximum redshift of the gravitational well in the external
vacuum region. Israel's theorem is recovered continuously in the limit of
infinite redshift. This result provides a first extension of no-hair theorems
to ultracompact stars, wormholes, and other exotic objects, and paves the way
for the construction of similar results for stationary spacetimes describing
rotating objects.
| [
{
"created": "Fri, 18 Jan 2019 19:00:01 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Jun 2019 09:49:59 GMT",
"version": "v2"
}
] | 2019-06-20 | [
[
"Barceló",
"Carlos",
""
],
[
"Carballo-Rubio",
"Raúl",
""
],
[
"Liberati",
"Stefano",
""
]
] | The simplicity of black holes, as characterized by no-hair theorems, is one of the most important mathematical results in the framework of general relativity. Are these theorems unique to black hole spacetimes, or do they also constrain the geometry around regions of spacetime with arbitrarily large (although finite) redshift? This paper presents a systematic study of this question and illustrates that no-hair theorems are not restricted to spacetimes with event horizons but are instead characteristic of spacetimes with deep enough gravitational wells, extending Israel's theorem to static spacetimes without event horizons that contain small deviations from spherical symmetry. Instead of a uniqueness result, we obtain a theorem that constrains the allowed deviations from the Schwarzschild metric and guarantees that these deviations decrease with the maximum redshift of the gravitational well in the external vacuum region. Israel's theorem is recovered continuously in the limit of infinite redshift. This result provides a first extension of no-hair theorems to ultracompact stars, wormholes, and other exotic objects, and paves the way for the construction of similar results for stationary spacetimes describing rotating objects. |
1802.00916 | Kiyoshi Shiraishi | Takuya Maki and Kiyoshi Shiraishi | Three-dimensional black holes and solitons in higher-dimensional
theories with compactification | 8 pages, no figure | Classical and Quantum Gravity 11, No. 11, pp. 2781-2787, 1994 | 10.1088/0264-9381/11/11/018 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Several types of static solutions to Einstein's equations coupled with
antisymmetric tensor fields are found in $(2+N+1)$-dimensional spacetime. The
solutions describe a product of a three-dimensional radially symmetric
spacetime and an internal maximally symmetric manifold. The scale of the
internal space may depend on the radial distance from the origin in these
solutions.
| [
{
"created": "Sat, 3 Feb 2018 05:25:02 GMT",
"version": "v1"
}
] | 2018-02-06 | [
[
"Maki",
"Takuya",
""
],
[
"Shiraishi",
"Kiyoshi",
""
]
] | Several types of static solutions to Einstein's equations coupled with antisymmetric tensor fields are found in $(2+N+1)$-dimensional spacetime. The solutions describe a product of a three-dimensional radially symmetric spacetime and an internal maximally symmetric manifold. The scale of the internal space may depend on the radial distance from the origin in these solutions. |
gr-qc/9604043 | Christian Wiesendanger | C. Wiesendanger | A Poincare Gauge Theory of Gravitation in Minkowski Spacetime | 18 pages, LaTex, to appear in the Proceedings on 'Quantum Gravity',
11-19 May 1995 (Erice, Italy) | null | null | DIAS-STP 95-27 | gr-qc | null | The conventional role of spacetime geometry in the description of gravity is
pointed out. Global Poincar$\acute{\mbox{e}}$ symmetry as an inner symmetry of
field theories defined on a fixed Minkowski spacetime is discussed. Its
extension to local {\bf P\/} gauge symmetry and the corresponding {\bf P\/}
gauge fields are introduced. Their minimal coupling to matter is obtained. The
scaling behaviour of the partition function of a spinor in {\bf P\/} gauge
field backgrounds is computed. The corresponding renormalization constraint is
used to determine a minimal gauge field dynamics.
| [
{
"created": "Tue, 23 Apr 1996 17:05:57 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Wiesendanger",
"C.",
""
]
] | The conventional role of spacetime geometry in the description of gravity is pointed out. Global Poincar$\acute{\mbox{e}}$ symmetry as an inner symmetry of field theories defined on a fixed Minkowski spacetime is discussed. Its extension to local {\bf P\/} gauge symmetry and the corresponding {\bf P\/} gauge fields are introduced. Their minimal coupling to matter is obtained. The scaling behaviour of the partition function of a spinor in {\bf P\/} gauge field backgrounds is computed. The corresponding renormalization constraint is used to determine a minimal gauge field dynamics. |
2201.09584 | Javier Olmedo | Daniel del-Corral and Javier Olmedo | Breaking of isospectrality of quasinormal modes in nonrotating loop
quantum gravity black holes | 12 pages, 3 figures, typos corrected, matches published version | null | 10.1103/PhysRevD.105.064053 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the quasinormal frequencies of three effective geometries of
nonrotating regular black holes derived from loop quantum gravity. Concretely,
we consider the Ashtekar-Olmedo-Singh and two Gambini-Olmedo-Pullin
prescriptions. We compute the quasinormal frequencies of axial and polar
perturbations adopting a WKB method. We show that they differ from those of
classical general relativity and, more importantly, that isospectrality is
broken. Nevertheless, these deviations are tiny, even for microscopic black
holes, and they decay following an inverse power law of the size of the mass of
the black holes. For the sake of completeness, we also analyze scalar and
vector perturbations, reaching similar conclusions.
| [
{
"created": "Mon, 24 Jan 2022 10:48:46 GMT",
"version": "v1"
},
{
"created": "Mon, 11 Apr 2022 14:20:13 GMT",
"version": "v2"
}
] | 2022-04-12 | [
[
"del-Corral",
"Daniel",
""
],
[
"Olmedo",
"Javier",
""
]
] | We study the quasinormal frequencies of three effective geometries of nonrotating regular black holes derived from loop quantum gravity. Concretely, we consider the Ashtekar-Olmedo-Singh and two Gambini-Olmedo-Pullin prescriptions. We compute the quasinormal frequencies of axial and polar perturbations adopting a WKB method. We show that they differ from those of classical general relativity and, more importantly, that isospectrality is broken. Nevertheless, these deviations are tiny, even for microscopic black holes, and they decay following an inverse power law of the size of the mass of the black holes. For the sake of completeness, we also analyze scalar and vector perturbations, reaching similar conclusions. |
gr-qc/9609070 | Jacek Gruszczak | Jacek Gruszczak | Discrete Spectrum of the Deficit Angle and the Differential Structure of
a Cosmic String | 20 pages, LaTeX,amsfonts, published version, to appear in
International J. of Th. Phys | null | null | null | gr-qc | null | Differential properties of Klein-Gordon and electromagnetic fields on the
space-time of a straight cosmic string are studied with the help of methods of
the differential space theory. It is shown that these fields are smooth in the
interior of the cosmic string space-time and that they loose this property at
the singular boundary except for the cosmic string space-times with the
following deficit angles : Delta=2\pi*(1-1/n), n=1,2,... A connection between
smoothness of fields at the conical singularity and the scalar and
electromagnetic conical bremsstrahlung is discussed. It is also argued that the
smoothness assumption of fields at the singularity is equivalent to the Aliev
and Gal'tsov "quantization" condition leading to the above mentioned discrete
spectrum of the deficit angle.
| [
{
"created": "Mon, 30 Sep 1996 12:15:35 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Sep 2007 13:35:19 GMT",
"version": "v2"
}
] | 2008-02-03 | [
[
"Gruszczak",
"Jacek",
""
]
] | Differential properties of Klein-Gordon and electromagnetic fields on the space-time of a straight cosmic string are studied with the help of methods of the differential space theory. It is shown that these fields are smooth in the interior of the cosmic string space-time and that they loose this property at the singular boundary except for the cosmic string space-times with the following deficit angles : Delta=2\pi*(1-1/n), n=1,2,... A connection between smoothness of fields at the conical singularity and the scalar and electromagnetic conical bremsstrahlung is discussed. It is also argued that the smoothness assumption of fields at the singularity is equivalent to the Aliev and Gal'tsov "quantization" condition leading to the above mentioned discrete spectrum of the deficit angle. |
0902.3283 | Takeshi Fukuyama | Takeshi Fukuyama | Gravitational Field as a Generalized Gauge Field Revisited | 6 pages, no figure | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We add some comments to our old paper \cite{F-U} where the metric tensor was
introduced as the gauge theory of general coordinate transformation. This
formulation is more satisfactorily completed than the original one if it is
required to be valid for arbitrary n dimensional spacetime. That is, our
formulation asserts the presence of extra dimensions positively.
| [
{
"created": "Thu, 19 Feb 2009 02:13:54 GMT",
"version": "v1"
}
] | 2009-02-20 | [
[
"Fukuyama",
"Takeshi",
""
]
] | We add some comments to our old paper \cite{F-U} where the metric tensor was introduced as the gauge theory of general coordinate transformation. This formulation is more satisfactorily completed than the original one if it is required to be valid for arbitrary n dimensional spacetime. That is, our formulation asserts the presence of extra dimensions positively. |
1911.09855 | Akash Kumar Mishra | Akash K Mishra, Sumanta Chakraborty | Strong Cosmic Censorship in higher curvature gravity | 20 pages, References Updated, Accepted in PRD | Phys. Rev. D 101, 064041 (2020) | 10.1103/PhysRevD.101.064041 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Deterministic nature of general relativity is ensured by the strong cosmic
censorship conjecture, which asserts that spacetime cannot be extended beyond
Cauchy horizon with square integrable connection. Although this conjecture
holds true for asymptotically flat black hole spacetimes in general relativity,
a potential violation of this conjecture occurs in charged asymptotically de
Sitter spacetimes. Since it is expected that Einstein-Hilbert action will
involve higher curvature corrections, in this article we have studied whether
one can restore faith in the strong cosmic censorship when higher curvature
corrections to general relativity are considered. Contrary to our expectations,
we have explicitly demonstrated that not only a violation to the conjecture
occurs near extremality, but the violation appears to become stronger as the
strength of the higher curvature term increases.
| [
{
"created": "Fri, 22 Nov 2019 04:47:24 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Mar 2020 12:25:20 GMT",
"version": "v2"
}
] | 2020-03-23 | [
[
"Mishra",
"Akash K",
""
],
[
"Chakraborty",
"Sumanta",
""
]
] | Deterministic nature of general relativity is ensured by the strong cosmic censorship conjecture, which asserts that spacetime cannot be extended beyond Cauchy horizon with square integrable connection. Although this conjecture holds true for asymptotically flat black hole spacetimes in general relativity, a potential violation of this conjecture occurs in charged asymptotically de Sitter spacetimes. Since it is expected that Einstein-Hilbert action will involve higher curvature corrections, in this article we have studied whether one can restore faith in the strong cosmic censorship when higher curvature corrections to general relativity are considered. Contrary to our expectations, we have explicitly demonstrated that not only a violation to the conjecture occurs near extremality, but the violation appears to become stronger as the strength of the higher curvature term increases. |
gr-qc/0501008 | Ian Hawke | Maria Babiuc, Bela Szilagyi, Ian Hawke, Yosef Zlochower | Gravitational wave extraction based on Cauchy-characteristic extraction
and characteristic evolution | 11 pages, 5 figures; corrections after referee's comments; add
section on Teukolsky wave | Class.Quant.Grav. 22 (2005) 5089-5108 | 10.1088/0264-9381/22/23/011 | null | gr-qc | null | We implement a code to find the gravitational news at future null infinity by
using data from a Cauchy code as boundary data for a characteristic code. This
technique of Cauchy-characteristic Extraction (CCE) allows for the unambiguous
extraction of gravitational waves from numerical simulations.
| [
{
"created": "Tue, 4 Jan 2005 15:14:59 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Sep 2005 09:01:59 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Babiuc",
"Maria",
""
],
[
"Szilagyi",
"Bela",
""
],
[
"Hawke",
"Ian",
""
],
[
"Zlochower",
"Yosef",
""
]
] | We implement a code to find the gravitational news at future null infinity by using data from a Cauchy code as boundary data for a characteristic code. This technique of Cauchy-characteristic Extraction (CCE) allows for the unambiguous extraction of gravitational waves from numerical simulations. |
2007.03403 | Yujie Tan | Cheng-Gang Qin, Yu-Jie Tan, and Cheng-Gang Shao | Relativistic tidal effects on clock-comparison experiments | null | null | 10.1088/1361-6382/ab01ae | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the relativistic tidal effects on frequency shift of
clock-comparison experiments. The relativistic formulation for frequency shift
and time transfer is derived in the gravitational field of a tidal,
axisymmetric, and rotating Earth. With the help of Love numbers describing the
tidal response of solid Earth, we formulize the mathematical connection between
tidal effects from the ground-based clock-comparison experiments and the local
gravity tides from the gravimeters, which in turn provides us an approach to
eliminate tidal influences on clock comparison with the local gravity tides
data. Moreover, we develop a method of the perturbed Kepler orbit to determine
relativistic effects of clock comparison for space missions, which allows more
precise calculations comparing to the conventional method of unperturbed Kepler
orbit. With this perturbed method, it can give the perturbation of relativistic
effects due to the orbital changes under the influences of tidal forces,
Earth's oblateness etc. In addition, as the applications of our results, we
simulate tidal effects in frequency shift for the clock comparison on the
ground and also give some estimates for TianQin mission and GPS.
| [
{
"created": "Tue, 7 Jul 2020 13:11:25 GMT",
"version": "v1"
}
] | 2020-07-08 | [
[
"Qin",
"Cheng-Gang",
""
],
[
"Tan",
"Yu-Jie",
""
],
[
"Shao",
"Cheng-Gang",
""
]
] | We consider the relativistic tidal effects on frequency shift of clock-comparison experiments. The relativistic formulation for frequency shift and time transfer is derived in the gravitational field of a tidal, axisymmetric, and rotating Earth. With the help of Love numbers describing the tidal response of solid Earth, we formulize the mathematical connection between tidal effects from the ground-based clock-comparison experiments and the local gravity tides from the gravimeters, which in turn provides us an approach to eliminate tidal influences on clock comparison with the local gravity tides data. Moreover, we develop a method of the perturbed Kepler orbit to determine relativistic effects of clock comparison for space missions, which allows more precise calculations comparing to the conventional method of unperturbed Kepler orbit. With this perturbed method, it can give the perturbation of relativistic effects due to the orbital changes under the influences of tidal forces, Earth's oblateness etc. In addition, as the applications of our results, we simulate tidal effects in frequency shift for the clock comparison on the ground and also give some estimates for TianQin mission and GPS. |
2307.15267 | Annalaura Stingo | C\'ecile Huneau, Annalaura Stingo, Zoe Wyatt | The global stability of the Kaluza-Klein spacetime | 80 pages | null | null | null | gr-qc math.AP | http://creativecommons.org/licenses/by/4.0/ | In this paper we show the classical global stability of the flat Kaluza-Klein
spacetime, which corresponds to Minkowski spacetime in $\m R^{1+4}$ with one
direction compactified on a circle. We consider small perturbations which are
allowed to vary in all directions including the compact direction. These
perturbations lead to the creation of massless modes and Klein-Gordon modes. On
the analytic side, this leads to a PDE system coupling wave equations to an
infinite sequence of Klein-Gordon equations with different masses. The
techniques we use are based purely in physical space using the vectorfield
method.
| [
{
"created": "Fri, 28 Jul 2023 02:23:52 GMT",
"version": "v1"
}
] | 2023-07-31 | [
[
"Huneau",
"Cécile",
""
],
[
"Stingo",
"Annalaura",
""
],
[
"Wyatt",
"Zoe",
""
]
] | In this paper we show the classical global stability of the flat Kaluza-Klein spacetime, which corresponds to Minkowski spacetime in $\m R^{1+4}$ with one direction compactified on a circle. We consider small perturbations which are allowed to vary in all directions including the compact direction. These perturbations lead to the creation of massless modes and Klein-Gordon modes. On the analytic side, this leads to a PDE system coupling wave equations to an infinite sequence of Klein-Gordon equations with different masses. The techniques we use are based purely in physical space using the vectorfield method. |
1511.07459 | Victor Shchigolev Konstantinovich | V. K. Shchigolev | Calculating Luminosity Distance versus Redshift in FLRW Cosmology via
Homotopy Perturbation Method | 6 pages, 1 figure. Submitted for publication in "Gravitation and
Cosmology" | Gravit. Cosmol. (2017) 23: 142 | 10.1134/S0202289317020098 | null | gr-qc physics.comp-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose an efficient analytical method for estimating the luminosity
distance in a homogenous Friedmann-Lema\^itre-Robertson-Walker (FLRW) model of
the Universe. This method is based on the homotopy perturbation method (HPM),
which has high accuracy in many nonlinear problems, and can be easily
implemented. For analytical calculation of the luminosity distance, we offer to
proceed not from the computation of the integral, which determines it, but from
the solution of a certain differential equation with corresponding initial
conditions. Solving this equation by means of HPM, we obtain the approximate
analytical expressions for the luminosity distance as a function of redshift
for two different types of homotopy. Possible extension of this method to other
cosmological models is also discussed.
| [
{
"created": "Mon, 23 Nov 2015 21:06:46 GMT",
"version": "v1"
},
{
"created": "Sat, 28 Nov 2015 19:37:13 GMT",
"version": "v2"
},
{
"created": "Tue, 1 Dec 2015 14:54:00 GMT",
"version": "v3"
},
{
"created": "Sun, 27 Nov 2016 18:53:58 GMT",
"version": "v4"
}
] | 2017-05-29 | [
[
"Shchigolev",
"V. K.",
""
]
] | We propose an efficient analytical method for estimating the luminosity distance in a homogenous Friedmann-Lema\^itre-Robertson-Walker (FLRW) model of the Universe. This method is based on the homotopy perturbation method (HPM), which has high accuracy in many nonlinear problems, and can be easily implemented. For analytical calculation of the luminosity distance, we offer to proceed not from the computation of the integral, which determines it, but from the solution of a certain differential equation with corresponding initial conditions. Solving this equation by means of HPM, we obtain the approximate analytical expressions for the luminosity distance as a function of redshift for two different types of homotopy. Possible extension of this method to other cosmological models is also discussed. |
0710.0158 | Harald P. Pfeiffer | Michael Boyle, Duncan A. Brown, Lawrence E. Kidder, Abdul H. Mroue,
Harald P. Pfeiffer, Mark A. Scheel, Gregory B. Cook, Saul A. Teukolsky | High-accuracy comparison of numerical relativity simulations with
post-Newtonian expansions | Updated to agree with published version (various minor
clarifications; added description of AH finder in Sec IIB; added discussion
of tidal heating in Sec VC) | Phys.Rev.D76:124038,2007 | 10.1103/PhysRevD.76.124038 | null | gr-qc | null | Numerical simulations of 15 orbits of an equal-mass binary black hole system
are presented. Gravitational waveforms from these simulations, covering more
than 30 cycles and ending about 1.5 cycles before merger, are compared with
those from quasi-circular zero-spin post-Newtonian (PN) formulae. The
cumulative phase uncertainty of these comparisons is about 0.05 radians,
dominated by effects arising from the small residual spins of the black holes
and the small residual orbital eccentricity in the simulations. Matching
numerical results to PN waveforms early in the run yields excellent agreement
(within 0.05 radians) over the first $\sim 15$ cycles, thus validating the
numerical simulation and establishing a regime where PN theory is accurate. In
the last 15 cycles to merger, however, {\em generic} time-domain Taylor
approximants build up phase differences of several radians. But, apparently by
coincidence, one specific post-Newtonian approximant, TaylorT4 at 3.5PN order,
agrees much better with the numerical simulations, with accumulated phase
differences of less than 0.05 radians over the 30-cycle waveform.
Gravitational-wave amplitude comparisons are also done between numerical
simulations and post-Newtonian, and the agreement depends on the post-Newtonian
order of the amplitude expansion: the amplitude difference is about 6--7% for
zeroth order and becomes smaller for increasing order. A newly derived 3.0PN
amplitude correction improves agreement significantly ($<1%$ amplitude
difference throughout most of the run, increasing to 4% near merger) over the
previously known 2.5PN amplitude terms.
| [
{
"created": "Sun, 30 Sep 2007 17:28:58 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Feb 2008 21:22:09 GMT",
"version": "v2"
}
] | 2010-04-06 | [
[
"Boyle",
"Michael",
""
],
[
"Brown",
"Duncan A.",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"Mroue",
"Abdul H.",
""
],
[
"Pfeiffer",
"Harald P.",
""
],
[
"Scheel",
"Mark A.",
""
],
[
"Cook",
"Gregory B.",
""... | Numerical simulations of 15 orbits of an equal-mass binary black hole system are presented. Gravitational waveforms from these simulations, covering more than 30 cycles and ending about 1.5 cycles before merger, are compared with those from quasi-circular zero-spin post-Newtonian (PN) formulae. The cumulative phase uncertainty of these comparisons is about 0.05 radians, dominated by effects arising from the small residual spins of the black holes and the small residual orbital eccentricity in the simulations. Matching numerical results to PN waveforms early in the run yields excellent agreement (within 0.05 radians) over the first $\sim 15$ cycles, thus validating the numerical simulation and establishing a regime where PN theory is accurate. In the last 15 cycles to merger, however, {\em generic} time-domain Taylor approximants build up phase differences of several radians. But, apparently by coincidence, one specific post-Newtonian approximant, TaylorT4 at 3.5PN order, agrees much better with the numerical simulations, with accumulated phase differences of less than 0.05 radians over the 30-cycle waveform. Gravitational-wave amplitude comparisons are also done between numerical simulations and post-Newtonian, and the agreement depends on the post-Newtonian order of the amplitude expansion: the amplitude difference is about 6--7% for zeroth order and becomes smaller for increasing order. A newly derived 3.0PN amplitude correction improves agreement significantly ($<1%$ amplitude difference throughout most of the run, increasing to 4% near merger) over the previously known 2.5PN amplitude terms. |
2006.03911 | Peter K.F. Kuhfittig | Peter K.F. Kuhfittig | Accounting for the large radial tension in Morris-Thorne wormholes | 9 pages, 1 figure | Eur. Phys. J. Plus, vol. 135, ID: 50 (2020) | 10.1140/epjp/s13360-020-00511-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is well known that a Morris-Thorne wormhole can only be held open by
violating the null energy condition, physically realizable by the use of
"exotic matter." Unfortunately, even a small or moderately-sized wormhole would
have a radial tension equal to that of the interior of a massive neutron star.
So outside a neutron-star setting, such an outcome is problematical at best,
calling for more than an appeal to exotic matter whose introduction had a
completely different objective and with possibly different outcomes. The
purpose of this paper is to account for the enormous radial tension in three
ways: (1) directly invoking noncommutative geometry, an offshoot of string
theory, (2) appealing to noncommutative geometry in conjunction with $f(R)$
modified gravity, and (3) determining the possible effect of a small extra
dimension.
| [
{
"created": "Sat, 6 Jun 2020 16:36:36 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Jun 2020 17:13:27 GMT",
"version": "v2"
}
] | 2020-06-29 | [
[
"Kuhfittig",
"Peter K. F.",
""
]
] | It is well known that a Morris-Thorne wormhole can only be held open by violating the null energy condition, physically realizable by the use of "exotic matter." Unfortunately, even a small or moderately-sized wormhole would have a radial tension equal to that of the interior of a massive neutron star. So outside a neutron-star setting, such an outcome is problematical at best, calling for more than an appeal to exotic matter whose introduction had a completely different objective and with possibly different outcomes. The purpose of this paper is to account for the enormous radial tension in three ways: (1) directly invoking noncommutative geometry, an offshoot of string theory, (2) appealing to noncommutative geometry in conjunction with $f(R)$ modified gravity, and (3) determining the possible effect of a small extra dimension. |
1106.2425 | Daisuke Nitta | Daisuke Nitta, Takeshi Chiba, Naoshi Sugiyama | Shadows of Colliding Black Holes | 5 pages, 1 figure, accepted for publication in PRD | Phys.Rev.D84:063008,2011 | 10.1103/PhysRevD.84.063008 | null | gr-qc astro-ph.CO astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the shadows of colliding black holes using the Kastor-Traschen
cosmological multiblack hole solution that is an exact solution describing the
collision of maximally charged black holes with a positive cosmological
constant. We find that in addition to the shadow of each black hole, an
eyebrowlike structure appears as the black holes come close to each other.
These features can be used as probes to find the multiblack hole system at the
final stage of its merger process.
| [
{
"created": "Mon, 13 Jun 2011 12:16:48 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Oct 2011 09:50:40 GMT",
"version": "v2"
}
] | 2011-10-20 | [
[
"Nitta",
"Daisuke",
""
],
[
"Chiba",
"Takeshi",
""
],
[
"Sugiyama",
"Naoshi",
""
]
] | We compute the shadows of colliding black holes using the Kastor-Traschen cosmological multiblack hole solution that is an exact solution describing the collision of maximally charged black holes with a positive cosmological constant. We find that in addition to the shadow of each black hole, an eyebrowlike structure appears as the black holes come close to each other. These features can be used as probes to find the multiblack hole system at the final stage of its merger process. |
1404.5529 | Daniel Canarutto | Daniel Canarutto | Nature's software | Essay presented for the 2011 contest, "Is Reality Digital or
Analog?", of the Foundational Questions Institute (FQXi) | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I bring forward some arguments to support the thesis that nature is
fundamentally discrete, and present my own thoughts about the direction in
which one could look for a possible, consistent "theory of everything"
describing gravitation and quantum particles.
| [
{
"created": "Sun, 20 Apr 2014 17:00:25 GMT",
"version": "v1"
}
] | 2014-04-23 | [
[
"Canarutto",
"Daniel",
""
]
] | I bring forward some arguments to support the thesis that nature is fundamentally discrete, and present my own thoughts about the direction in which one could look for a possible, consistent "theory of everything" describing gravitation and quantum particles. |
2408.00022 | Salim Shekh Dr. | S. H. Shekh, Anirudh Pradhan, S. P. Gaikwad, K. R. Mule | Cosmography in $f(Q,T)$ gravity with the specific $H(z)$ | 18 pages, 10 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The dynamics of perfect fluid as a source in the context of modified gravity,
specifically $f(Q,T)$ gravity, are examined within the
Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmological model. This gravity
is a generic function of the non-metricity scalar $Q$ and its trace $T$. We
investigate the characteristics of the derived cosmological model using a
parameterized form of Hubble's parameter, $H(z) = H_0\left[\Omega_{0m}(1+z)^3 +
(1-\Omega_{0m})\right]^{\frac{1}{2}}$ (Mahmood et al. Int. J. Geom. Methods
Mod. Phys., https://doi.org/10.1142/S0219887824502049). Our examination reveals
how physical parameters such as energy density, pressure, and the equation of
state parameter, among others, in our model accurately describe the physical
behavior of the cosmos. Furthermore, we explore the kinematic parameters in our
model, which provide valuable insights into the cosmos's expansion history,
including its acceleration, deceleration, and the evolution of its large-scale
structure. By exploring these aspects, we gain a deeper understanding of the
cosmos's dynamics and evolution within the context of modified gravity.
| [
{
"created": "Wed, 31 Jul 2024 02:41:07 GMT",
"version": "v1"
}
] | 2024-08-02 | [
[
"Shekh",
"S. H.",
""
],
[
"Pradhan",
"Anirudh",
""
],
[
"Gaikwad",
"S. P.",
""
],
[
"Mule",
"K. R.",
""
]
] | The dynamics of perfect fluid as a source in the context of modified gravity, specifically $f(Q,T)$ gravity, are examined within the Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmological model. This gravity is a generic function of the non-metricity scalar $Q$ and its trace $T$. We investigate the characteristics of the derived cosmological model using a parameterized form of Hubble's parameter, $H(z) = H_0\left[\Omega_{0m}(1+z)^3 + (1-\Omega_{0m})\right]^{\frac{1}{2}}$ (Mahmood et al. Int. J. Geom. Methods Mod. Phys., https://doi.org/10.1142/S0219887824502049). Our examination reveals how physical parameters such as energy density, pressure, and the equation of state parameter, among others, in our model accurately describe the physical behavior of the cosmos. Furthermore, we explore the kinematic parameters in our model, which provide valuable insights into the cosmos's expansion history, including its acceleration, deceleration, and the evolution of its large-scale structure. By exploring these aspects, we gain a deeper understanding of the cosmos's dynamics and evolution within the context of modified gravity. |
0903.0081 | Davood Momeni | D.Momeni, A.Azadi | Phase transition in Schwarzschild-de Sitter spacetime | 7 pages,no figures,RevTex, Typos corrected and references added | Astrophysics and Space Science, vol. 317, no. 3.(2008)-pp. 231-234 | 10.1007/s10509-008-9883-7 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using a static massive spherically symmetric scalar field coupled to gravity
in the Schwarzschild-de Sitter (SdS) background, first we consider some
asymptotic solutions near horizon and their local equations of state(E.O.S) on
them. We show that near cosmological and event horizons our scalar field
behaves as a dust. At the next step near two pure de-Sitter or Schwarzschild
horizons we obtain a coupling dependent pressure to energy density ratio. In
the case of a minimally couplling this ratio is -1 which springs to the mind
thermodynamical behavior of dark energy. If having a negative pressure behavior
near these horizons we concluded that the coupling constant must be $\xi<{1/4}$
>. Therefore we derive a new constraint on the value of our coupling $\xi$ .
These two different behaviors of unique matter in the distinct regions of
spacetime at present era can be interpreted as a phase transition from dark
matter to dark energy in the cosmic scales and construct a unified scenario.
| [
{
"created": "Sat, 28 Feb 2009 14:49:28 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Mar 2009 15:44:11 GMT",
"version": "v2"
}
] | 2009-03-24 | [
[
"Momeni",
"D.",
""
],
[
"Azadi",
"A.",
""
]
] | Using a static massive spherically symmetric scalar field coupled to gravity in the Schwarzschild-de Sitter (SdS) background, first we consider some asymptotic solutions near horizon and their local equations of state(E.O.S) on them. We show that near cosmological and event horizons our scalar field behaves as a dust. At the next step near two pure de-Sitter or Schwarzschild horizons we obtain a coupling dependent pressure to energy density ratio. In the case of a minimally couplling this ratio is -1 which springs to the mind thermodynamical behavior of dark energy. If having a negative pressure behavior near these horizons we concluded that the coupling constant must be $\xi<{1/4}$ >. Therefore we derive a new constraint on the value of our coupling $\xi$ . These two different behaviors of unique matter in the distinct regions of spacetime at present era can be interpreted as a phase transition from dark matter to dark energy in the cosmic scales and construct a unified scenario. |
gr-qc/9702026 | Michael Pfenning | Michael J. Pfenning, L.H. Ford | The unphysical nature of "Warp Drive" | 11 pages, 3 figures, latex. This revision corrects a typographical
sign error in Eq. (3) | Class.Quant.Grav. 14 (1997) 1743-1751 | 10.1088/0264-9381/14/7/011 | null | gr-qc | null | We will apply the quantum inequality type restrictions to Alcubierre's warp
drive metric on a scale in which a local region of spacetime can be considered
``flat''. These are inequalities that restrict the magnitude and extent of the
negative energy which is needed to form the warp drive metric. From this we are
able to place limits on the parameters of the ``Warp Bubble''. It will be shown
that the bubble wall thickness is on the order of only a few hundred Planck
lengths. Then we will show that the total integrated energy density needed to
maintain the warp metric with such thin walls is physically unattainable.
| [
{
"created": "Thu, 13 Feb 1997 23:24:10 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Mar 1997 22:18:15 GMT",
"version": "v2"
},
{
"created": "Thu, 15 Mar 2001 16:47:53 GMT",
"version": "v3"
}
] | 2009-10-30 | [
[
"Pfenning",
"Michael J.",
""
],
[
"Ford",
"L. H.",
""
]
] | We will apply the quantum inequality type restrictions to Alcubierre's warp drive metric on a scale in which a local region of spacetime can be considered ``flat''. These are inequalities that restrict the magnitude and extent of the negative energy which is needed to form the warp drive metric. From this we are able to place limits on the parameters of the ``Warp Bubble''. It will be shown that the bubble wall thickness is on the order of only a few hundred Planck lengths. Then we will show that the total integrated energy density needed to maintain the warp metric with such thin walls is physically unattainable. |
0707.2256 | Eduard Alexis Larranaga Rubio | Alexis Larranaga | On the First Law of Thermodynamics for (2+1) Dimensional Charged BTZ
Black Hole and Charged de Sitter Space | 4 pages | Turk. J. Phys. 32, 1 (2008) | null | null | gr-qc | null | In this paper we will show that using the cosmological constant as a new
thermodynamical state variable, the differential and integral mass formulas of
the first law of thermodynamics for asymptotic flat spacetimes can be extended
to (2+1) dimensional charged BTZ black holes and charged de Sitter space.
| [
{
"created": "Mon, 16 Jul 2007 02:52:17 GMT",
"version": "v1"
}
] | 2008-03-06 | [
[
"Larranaga",
"Alexis",
""
]
] | In this paper we will show that using the cosmological constant as a new thermodynamical state variable, the differential and integral mass formulas of the first law of thermodynamics for asymptotic flat spacetimes can be extended to (2+1) dimensional charged BTZ black holes and charged de Sitter space. |
gr-qc/9502012 | Baburova O. V. | O. V. Babourova, B. N. Frolov, M. Yu. Koroliov (Department of
Mathematics, Moscow State Pedagogical University) | Peculiarities of Matter Motion in Metric-Affine Gravitational Theory | 6 pages | null | null | EFI-95-02 | gr-qc | null | On the basis of the Lie derivative method in a metric-affine space-time it is
shown that in the metric-affine gravitational theory the energy-momentum
conservation law and therefore the equations of the matter motion are the
consequence (as in the GR) of the gravitational field equations. The possi-
bility of the detection of the space-time non-metric properties is discussed.
| [
{
"created": "Mon, 6 Feb 1995 13:50:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Babourova",
"O. V.",
"",
"Department of\n Mathematics, Moscow State Pedagogical University"
],
[
"Frolov",
"B. N.",
"",
"Department of\n Mathematics, Moscow State Pedagogical University"
],
[
"Koroliov",
"M. Yu.",
"",
"Department of\n Mathematics, Moscow... | On the basis of the Lie derivative method in a metric-affine space-time it is shown that in the metric-affine gravitational theory the energy-momentum conservation law and therefore the equations of the matter motion are the consequence (as in the GR) of the gravitational field equations. The possi- bility of the detection of the space-time non-metric properties is discussed. |
2308.07634 | Junpei Harada | Junpei Harada | Dark energy in conformal Killing gravity | v2: 8 pages, 4 figures, accepted for publication in Phys.Rev.D | Phys. Rev. D 108, 104037 (2023) | 10.1103/PhysRevD.108.104037 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The Friedmann equation, augmented with an additional term that effectively
takes on the role of dark energy, is demonstrated to be an exact solution to
the recently proposed gravitational theory named "conformal Killing gravity."
This theory does not explicitly incorporate dark energy. This finding suggests
that there is no necessity to postulate the existence of dark energy as an
independent physical entity. The dark energy derived from this theory is
characterized by a specific equation of state parameter, denoted as $\omega$,
which is uniquely determined to be $-5/3$. If this effective dark energy is
present, typically around 5% of the total energy density at the present time,
and under the assumption of density parameters for matter and the cosmological
constant, $\Omega_{\rm m}\sim 0.25$ and $\Omega_\Lambda \sim 0.7$,
respectively, the expansion of the universe at low redshifts ($z < 1.5$) can
exceed expectations, while the expansion at $z > 1.5$ remains unchanged. This
offers a potential solution to the Hubble tension problem. Alternatively,
effective dark energy could be a dominant component in the present-day
universe. In this scenario, there is also the potential to address the Hubble
tension, and furthermore, it resolves the coincidence problem associated with
the cosmological constant.
| [
{
"created": "Tue, 15 Aug 2023 08:31:15 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Nov 2023 03:20:43 GMT",
"version": "v2"
}
] | 2023-11-20 | [
[
"Harada",
"Junpei",
""
]
] | The Friedmann equation, augmented with an additional term that effectively takes on the role of dark energy, is demonstrated to be an exact solution to the recently proposed gravitational theory named "conformal Killing gravity." This theory does not explicitly incorporate dark energy. This finding suggests that there is no necessity to postulate the existence of dark energy as an independent physical entity. The dark energy derived from this theory is characterized by a specific equation of state parameter, denoted as $\omega$, which is uniquely determined to be $-5/3$. If this effective dark energy is present, typically around 5% of the total energy density at the present time, and under the assumption of density parameters for matter and the cosmological constant, $\Omega_{\rm m}\sim 0.25$ and $\Omega_\Lambda \sim 0.7$, respectively, the expansion of the universe at low redshifts ($z < 1.5$) can exceed expectations, while the expansion at $z > 1.5$ remains unchanged. This offers a potential solution to the Hubble tension problem. Alternatively, effective dark energy could be a dominant component in the present-day universe. In this scenario, there is also the potential to address the Hubble tension, and furthermore, it resolves the coincidence problem associated with the cosmological constant. |
1909.07271 | Susanne Schander | S. Schander, T. Thiemann | Quantum Cosmological Backreactions IV: Constrained Quantum Cosmological
Perturbation Theory | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This is the fourth paper in a series of four in which we use space adiabatic
methods in order to incorporate backreactions among the homogeneous and between
the homogeneous and inhomogeneous degrees of freedom in quantum cosmological
perturbation theory. In this paper, we finally consider the gauge invariant
scalar (Mukhanov-Sasaki) and tensor (primordial gravitational wave)
inhomogeneous perturbations of General Relativity coupled to an inflaton field
which arise from a careful constraint analysis of this system up to second
order in the perturbations. The simultaneous quantisation of the homogeneous
and inhomogeneous degrees of freedom suggests the space adiabatic perturbation
theory as an approximation scheme in order to capture the backreaction effects
between these two sets of degrees of freedom. We are confronted with all the
challenges at once that we found in the simpler models treated in this series
of papers. We are able to compute these effects up to second order in the
adiabatic parameter and find significant modifications as compared to earlier
derivations of the effective quantum dynamics of the homogeneous sector.
| [
{
"created": "Mon, 16 Sep 2019 15:20:37 GMT",
"version": "v1"
}
] | 2019-09-17 | [
[
"Schander",
"S.",
""
],
[
"Thiemann",
"T.",
""
]
] | This is the fourth paper in a series of four in which we use space adiabatic methods in order to incorporate backreactions among the homogeneous and between the homogeneous and inhomogeneous degrees of freedom in quantum cosmological perturbation theory. In this paper, we finally consider the gauge invariant scalar (Mukhanov-Sasaki) and tensor (primordial gravitational wave) inhomogeneous perturbations of General Relativity coupled to an inflaton field which arise from a careful constraint analysis of this system up to second order in the perturbations. The simultaneous quantisation of the homogeneous and inhomogeneous degrees of freedom suggests the space adiabatic perturbation theory as an approximation scheme in order to capture the backreaction effects between these two sets of degrees of freedom. We are confronted with all the challenges at once that we found in the simpler models treated in this series of papers. We are able to compute these effects up to second order in the adiabatic parameter and find significant modifications as compared to earlier derivations of the effective quantum dynamics of the homogeneous sector. |
1412.8384 | James Ira Thorpe | M. Armano, H. Audley, G. Auger, J. Baird, P. Binetruy, M. Born, D.
Bortoluzzi, N. Brandt, A. Bursi, M. Caleno, A. Cavalleri, A. Cesarini, M.
Cruise, C. Cutler, K. Danzmann, I. Diepholz, R. Dolesi, N. Dunbar, L.
Ferraioli, V. Ferroni, E. Fitzsimons, M. Freschi, J. Gallegos, C. Garcia.
Marirrodriga, R. Gerndt, LI. Gesa, F. Gibert, D. Giardini, R. Giusteri, C.
Grimani, I. Harrison, G. Heinzel, M. Hewitson, D. Hollington, M. Hueller, J.
Huesler, H. Inchauspe, O. Jennrich, P. Jetzer, B. Johlander, N. Karnesis, B.
Kaune, N. Korsakova, C. Killow, I. Lloro, R. Maarschalkerweerd, S. Madden, P.
Maghami, D. Mance, V. Martin, F. Martin-Porqueras, I. Mateos, P. McNamara, J.
Mendes, L. Mendes, A. Moroni, M. Nofrarias, S. Paczkowski, M. Perreur-Lloyd,
A. Petiteau, P. Pivato, E. Plagnol, P. Prat, U. Ragnit, J. Ramos-Castro, J.
Reiche, J. A. Romera. Perez, D. Robertson, H. Rozemeijer, G. Russano, P.
Sarra, A. Schleicher, J. Slutsky, C. F. Sopuerta, T. Sumner, D. Texier, J.
Thorpe, C. Trenkel, H. B. Tu, D. Vetrugno, S. Vitale, G. Wanner, H. Ward, S.
Waschke, P. Wass, D. Wealthy, S. Wen, W. Weber, A. Wittchen, C. Zanoni, T.
Ziegler, P. Zweifel | Free-flight experiments in LISA Pathfinder | 13 pages, 5 figures. Accepted to Journal Of Physics, Conference
Series. Presented at 10th International LISA Symposium, May 2014,
Gainesville, FL, USA | null | 10.1088/1742-6596/610/1/012006 | null | gr-qc astro-ph.IM | http://creativecommons.org/licenses/publicdomain/ | The LISA Pathfinder mission will demonstrate the technology of drag-free test
masses for use as inertial references in future space-based gravitational wave
detectors. To accomplish this, the Pathfinder spacecraft will perform drag-free
flight about a test mass while measuring the acceleration of this primary test
mass relative to a second reference test mass. Because the reference test mass
is contained within the same spacecraft, it is necessary to apply forces on it
to maintain its position and attitude relative to the spacecraft. These forces
are a potential source of acceleration noise in the LISA Pathfinder system that
are not present in the full LISA configuration. While LISA Pathfinder has been
designed to meet it's primary mission requirements in the presence of this
noise, recent estimates suggest that the on-orbit performance may be limited by
this `suspension noise'. The drift-mode or free-flight experiments provide an
opportunity to mitigate this noise source and further characterize the
underlying disturbances that are of interest to the designers of LISA-like
instruments. This article provides a high-level overview of these experiments
and the methods under development to analyze the resulting data.
| [
{
"created": "Mon, 29 Dec 2014 16:38:59 GMT",
"version": "v1"
}
] | 2015-06-11 | [
[
"Armano",
"M.",
""
],
[
"Audley",
"H.",
""
],
[
"Auger",
"G.",
""
],
[
"Baird",
"J.",
""
],
[
"Binetruy",
"P.",
""
],
[
"Born",
"M.",
""
],
[
"Bortoluzzi",
"D.",
""
],
[
"Brandt",
"N.",
""
... | The LISA Pathfinder mission will demonstrate the technology of drag-free test masses for use as inertial references in future space-based gravitational wave detectors. To accomplish this, the Pathfinder spacecraft will perform drag-free flight about a test mass while measuring the acceleration of this primary test mass relative to a second reference test mass. Because the reference test mass is contained within the same spacecraft, it is necessary to apply forces on it to maintain its position and attitude relative to the spacecraft. These forces are a potential source of acceleration noise in the LISA Pathfinder system that are not present in the full LISA configuration. While LISA Pathfinder has been designed to meet it's primary mission requirements in the presence of this noise, recent estimates suggest that the on-orbit performance may be limited by this `suspension noise'. The drift-mode or free-flight experiments provide an opportunity to mitigate this noise source and further characterize the underlying disturbances that are of interest to the designers of LISA-like instruments. This article provides a high-level overview of these experiments and the methods under development to analyze the resulting data. |
2303.02194 | Haidar Sheikhahmadi | Haidar Sheikhahmadi, Saheb Soroushfar, S.N. Sajadi, Tiberiu Harko | Astrophysical and electromagnetic emissivity properties of black holes
surrounded by a quintessence type exotic fluid in the Scalar-Vector-Tensor
Modified Gravity | 30 pages, including diagrams and tables | Eur. Phys. J. C (2023) 83: 814 | 10.1140/epjc/s10052-023-11980-3 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The astrophysical consequences of the presence of a quintessence scalar field
on the evolution of the horizon and on the accretion disk surrounding a static
black hole, in the Scalar-Vector-Tensor version of Modified Gravity (MOG), are
investigated. The positions of the stable circular orbits of the massive test
particles, moving around the central object, are obtained from the extremum of
the effective potential. Detailed calculations are also presented to
investigate the light deflection, shadow and Shapiro effect for such a black
hole. The electromagnetic properties of the accretion disks that form around
such black holes are considered in detail. The energy flux and efficiency
parameter are estimated analytically and numerically. A comparison with the
disk properties in Schwarzschild geometry is also performed. The quantum
properties of the black hole are also considered, and the Hawking temperature
and the mass loss rate due to the Hawking radiation are considered. The
obtained results may lead to the possibility of direct astrophysical tests of
black hole type objects in modified gravity theories.
| [
{
"created": "Fri, 3 Mar 2023 19:45:25 GMT",
"version": "v1"
}
] | 2023-09-15 | [
[
"Sheikhahmadi",
"Haidar",
""
],
[
"Soroushfar",
"Saheb",
""
],
[
"Sajadi",
"S. N.",
""
],
[
"Harko",
"Tiberiu",
""
]
] | The astrophysical consequences of the presence of a quintessence scalar field on the evolution of the horizon and on the accretion disk surrounding a static black hole, in the Scalar-Vector-Tensor version of Modified Gravity (MOG), are investigated. The positions of the stable circular orbits of the massive test particles, moving around the central object, are obtained from the extremum of the effective potential. Detailed calculations are also presented to investigate the light deflection, shadow and Shapiro effect for such a black hole. The electromagnetic properties of the accretion disks that form around such black holes are considered in detail. The energy flux and efficiency parameter are estimated analytically and numerically. A comparison with the disk properties in Schwarzschild geometry is also performed. The quantum properties of the black hole are also considered, and the Hawking temperature and the mass loss rate due to the Hawking radiation are considered. The obtained results may lead to the possibility of direct astrophysical tests of black hole type objects in modified gravity theories. |
2111.01871 | Alexei M. Frolov | Alexei M. Frolov | General Principles of Hamiltonian Formulations of the Metric Gravity | arXiv admin note: substantial text overlap with arXiv:2001.00275 | Yad. Fiz. (Phys. of Atomic Nuclei) {\bf 84}(5), 750 - 722 (2021) | 10.1134/S1063778821050069 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Principles of successful Hamiltonian approaches, which were developed to
describe free gravitational field(s) in the metric gravity, are formulated and
discussed. By using the standard $\Gamma-\Gamma$ Lagrangian ${\cal
L}_{\Gamma-\Gamma}$ of the metric GR we properly introduce all momenta of the
metric gravitational field and derive the both canonical $H_C$ and total $H_t$
Hamiltonians of the metric GR. We also developed an effective method which is
used to determine various Poisson brackets between analytical functions of the
basic dynamical variables, i.e., generalized coordinates $g_{\alpha\beta}$ and
momenta $\pi^{\mu\nu}$. In general, such variables can be chosen either from
the straight $\{ g_{\alpha\beta}, \pi^{\mu\nu} \}$, or dual $\{
g^{\alpha\beta}, \pi_{\mu\nu} \}$ sets of symplectic dynamical variables which
always arise (and complete each other) in any Hamiltonian formulation developed
for the coupled system of tensor fields. By applying canonical
transformation(s) of dynamical variables we reduce the canonical Hamiltonian
$H_C$ to its natural form. The natural form of canonical Hamiltonian provides
numerous advantages in actual applications to the metric GR, since the general
theory of dynamical systems with such Hamiltonians is well developed.
Furthermore, many analytical and numerically exact solutions have been found
and described in detail for dynamical systems with the Hamiltonians already
reduced to their natural forms. In particular, reduction of the canonical
Hamiltonian $H_C$ to its natural form allows one to derive the Jacobi equation
for the free gravitational field(s), which takes a particularly simple form.
| [
{
"created": "Tue, 2 Nov 2021 20:19:26 GMT",
"version": "v1"
}
] | 2021-12-22 | [
[
"Frolov",
"Alexei M.",
""
]
] | Principles of successful Hamiltonian approaches, which were developed to describe free gravitational field(s) in the metric gravity, are formulated and discussed. By using the standard $\Gamma-\Gamma$ Lagrangian ${\cal L}_{\Gamma-\Gamma}$ of the metric GR we properly introduce all momenta of the metric gravitational field and derive the both canonical $H_C$ and total $H_t$ Hamiltonians of the metric GR. We also developed an effective method which is used to determine various Poisson brackets between analytical functions of the basic dynamical variables, i.e., generalized coordinates $g_{\alpha\beta}$ and momenta $\pi^{\mu\nu}$. In general, such variables can be chosen either from the straight $\{ g_{\alpha\beta}, \pi^{\mu\nu} \}$, or dual $\{ g^{\alpha\beta}, \pi_{\mu\nu} \}$ sets of symplectic dynamical variables which always arise (and complete each other) in any Hamiltonian formulation developed for the coupled system of tensor fields. By applying canonical transformation(s) of dynamical variables we reduce the canonical Hamiltonian $H_C$ to its natural form. The natural form of canonical Hamiltonian provides numerous advantages in actual applications to the metric GR, since the general theory of dynamical systems with such Hamiltonians is well developed. Furthermore, many analytical and numerically exact solutions have been found and described in detail for dynamical systems with the Hamiltonians already reduced to their natural forms. In particular, reduction of the canonical Hamiltonian $H_C$ to its natural form allows one to derive the Jacobi equation for the free gravitational field(s), which takes a particularly simple form. |
gr-qc/0206059 | Zachary Wardell | Zachary E. Wardell (University of Missouri-Columbia) | Gravitational Radiation Damping and the Three-Body Problem | 16 pages, 3 Postscript figures, to appear in MNRAS | null | 10.1046/j.1365-8711.2002.05498.x | null | gr-qc astro-ph | null | A model of three-body motion is developed which includes the effects of
gravitational radiation reaction. The radiation reaction due to the emission of
gravitational waves is the only post-Newtonian effect that is included here.
For simplicity, all of the motion is taken to be planar. Two of the masses are
viewed as a binary system and the third mass, whose motion will be a fixed
orbit around the center-of-mass of the binary system, is viewed as a
perturbation. This model aims to describe the motion of a relativistic binary
pulsar that is perturbed by a third mass. Numerical integration of this
simplified model reveals that given the right initial conditions and parameters
one can see resonances. These (m,n) resonances are defined by the resonance
condition, $m\omega=2n\Omega$, where $m$ and $n$ are relatively prime integers
and $\omega$ and $\Omega$ are the angular frequencies of the binary orbit and
third mass orbit, respectively. The resonance condition consequently fixes a
value for the semimajor axis of the binary orbit for the duration of the
resonance; therefore, the binary energy remains constant on the average while
its angular momentum changes during the resonance.
| [
{
"created": "Thu, 20 Jun 2002 05:31:56 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Jul 2002 05:54:24 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Wardell",
"Zachary E.",
"",
"University of Missouri-Columbia"
]
] | A model of three-body motion is developed which includes the effects of gravitational radiation reaction. The radiation reaction due to the emission of gravitational waves is the only post-Newtonian effect that is included here. For simplicity, all of the motion is taken to be planar. Two of the masses are viewed as a binary system and the third mass, whose motion will be a fixed orbit around the center-of-mass of the binary system, is viewed as a perturbation. This model aims to describe the motion of a relativistic binary pulsar that is perturbed by a third mass. Numerical integration of this simplified model reveals that given the right initial conditions and parameters one can see resonances. These (m,n) resonances are defined by the resonance condition, $m\omega=2n\Omega$, where $m$ and $n$ are relatively prime integers and $\omega$ and $\Omega$ are the angular frequencies of the binary orbit and third mass orbit, respectively. The resonance condition consequently fixes a value for the semimajor axis of the binary orbit for the duration of the resonance; therefore, the binary energy remains constant on the average while its angular momentum changes during the resonance. |
1911.12034 | Yuri Pavlov | A. A. Grib, Yu. V. Pavlov | Static limit and Penrose effect in rotating reference frames | 12 pages, 2 figures | Theor. Math. Phys. 200 (2019) 1117-1125 | 10.1134/S004057791908004X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that effects similar to those for a rotating black hole arise for an
observer using a uniformly rotating reference frame in a flat space-time: a
surface appears such that no body can be stationary beyond this surface, while
the particle energy can be either zero or negative. Beyond this surface, which
is similar to the static limit for a rotating black hole, an effect similar to
the Penrose effect is possible. We consider the example where one of the
fragments of a particle that has decayed into two particles beyond the static
limit flies into the rotating reference frame inside the static limit and has
an energy greater than the original particle energy. We obtain constraints on
the relative velocity of the decay products during the Penrose process in the
rotating reference frame. We consider the problem of defining energy in a
noninertial reference frame. For a uniformly rotating reference frame, we
consider the states of particles with minimum energy and show the relation of
this quantity to the radiation frequency shift of the rotating body due to the
transverse Doppler effect.
| [
{
"created": "Wed, 27 Nov 2019 09:11:58 GMT",
"version": "v1"
}
] | 2019-11-28 | [
[
"Grib",
"A. A.",
""
],
[
"Pavlov",
"Yu. V.",
""
]
] | We show that effects similar to those for a rotating black hole arise for an observer using a uniformly rotating reference frame in a flat space-time: a surface appears such that no body can be stationary beyond this surface, while the particle energy can be either zero or negative. Beyond this surface, which is similar to the static limit for a rotating black hole, an effect similar to the Penrose effect is possible. We consider the example where one of the fragments of a particle that has decayed into two particles beyond the static limit flies into the rotating reference frame inside the static limit and has an energy greater than the original particle energy. We obtain constraints on the relative velocity of the decay products during the Penrose process in the rotating reference frame. We consider the problem of defining energy in a noninertial reference frame. For a uniformly rotating reference frame, we consider the states of particles with minimum energy and show the relation of this quantity to the radiation frequency shift of the rotating body due to the transverse Doppler effect. |
1010.0996 | Foek Hioe | F.T. Hioe and David Kuebel | Parameter Space for Orbits in the Schwarzschild Metric | 12 pages, 2 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Some features of a parametrized space of orbits in the Schwarzschild geometry
are described.
| [
{
"created": "Tue, 5 Oct 2010 19:44:40 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Nov 2010 21:34:17 GMT",
"version": "v2"
}
] | 2010-11-25 | [
[
"Hioe",
"F. T.",
""
],
[
"Kuebel",
"David",
""
]
] | Some features of a parametrized space of orbits in the Schwarzschild geometry are described. |
1509.03489 | Iver Brevik | Iver Brevik | Viscosity-Induced Crossing of the Phantom Barrier | 11 pages, latex, no figures, to appear in Entropy | Entropy, Vol. 17, pp. 6318-6328 (2015) | 10.3390/e17096318 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show explicitly, by using astrophysical data plus reasonable assumptions
for the bulk viscosity in the cosmic fluid, how the magnitude of this viscosity
may be high enough to drive the fluid from its position in the quintessence
region at present time $t=0$ across the barrier $w=-1$ into the phantom region
in the late universe. The phantom barrier is accordingly not a sharp
mathematical divide, but rather a fuzzy concept. We also calculate the limiting
forms of various thermodynamical quantities, including the rate of entropy
production, for a dark energy fluid near the future Big Rip singularity.
| [
{
"created": "Fri, 11 Sep 2015 13:05:35 GMT",
"version": "v1"
}
] | 2015-09-15 | [
[
"Brevik",
"Iver",
""
]
] | We show explicitly, by using astrophysical data plus reasonable assumptions for the bulk viscosity in the cosmic fluid, how the magnitude of this viscosity may be high enough to drive the fluid from its position in the quintessence region at present time $t=0$ across the barrier $w=-1$ into the phantom region in the late universe. The phantom barrier is accordingly not a sharp mathematical divide, but rather a fuzzy concept. We also calculate the limiting forms of various thermodynamical quantities, including the rate of entropy production, for a dark energy fluid near the future Big Rip singularity. |
gr-qc/9607076 | Herbert Balasin | H.Balasin | Geodesics for impulsive gravitational waves and the multiplication of
distributions | 14 pages, latex2e, amstex macros, no figures | Class.Quant.Grav. 14 (1997) 455-462 | 10.1088/0264-9381/14/2/018 | UWThPh-1996-46, TUW95-12 | gr-qc | null | We consider particle trajectories in the gravitational field of an impulsive
pp-wave. Due to the distributional character of the wave profile one inevitably
encounters an ambiguous point value $\theta(0)$. We show that this ambiguity
may be resolved by imposing covariant constancy of the square of the tangent.
Our result is consistent with Colombeau's multiplication of distributions.
| [
{
"created": "Tue, 30 Jul 1996 21:18:07 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Balasin",
"H.",
""
]
] | We consider particle trajectories in the gravitational field of an impulsive pp-wave. Due to the distributional character of the wave profile one inevitably encounters an ambiguous point value $\theta(0)$. We show that this ambiguity may be resolved by imposing covariant constancy of the square of the tangent. Our result is consistent with Colombeau's multiplication of distributions. |
1508.02291 | David W. Tian | David Wenjie Tian | Traversable wormholes and energy conditions in Lovelock-Brans-Dicke
gravity | 10 informative figures, 14 subfigures, 21 pages | null | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Following the recent theory of Lovelock-Brans-Dicke gravity, we continue to
investigate the conditions to support traversable wormholes by the
gravitational effects of spacetime parity and topology, which arise from the
nonminimal couplings of a background scalar field to the Chern-Pontryagin
density and the Gauss-Bonnet invariant. The flaring-out condition indicates
that a Morris-Thorne-type wormhole can be maintained by violating the
generalized null energy condition, and thus also breaking down the generalized
weak, strong, and dominant energy conditions; meanwhile, analyses of the
zero-tidal-force solution show that the standard null energy condition in
general relativity can still be respected by the physical matter threading the
wormhole. This way, the two topological effects have to dominate over the
ordinary-matter source of gravity, and the scalar field is preferred to be
noncanonical. By treating Brans-Dicke gravity as a reduced situation of
Lovelock-Brans-Dicke gravity, we also examine the Brans-Dicke wormholes and
energy conditions.
| [
{
"created": "Mon, 10 Aug 2015 15:39:31 GMT",
"version": "v1"
},
{
"created": "Sun, 30 Aug 2015 21:41:34 GMT",
"version": "v2"
},
{
"created": "Thu, 7 Jan 2016 16:06:14 GMT",
"version": "v3"
}
] | 2016-01-08 | [
[
"Tian",
"David Wenjie",
""
]
] | Following the recent theory of Lovelock-Brans-Dicke gravity, we continue to investigate the conditions to support traversable wormholes by the gravitational effects of spacetime parity and topology, which arise from the nonminimal couplings of a background scalar field to the Chern-Pontryagin density and the Gauss-Bonnet invariant. The flaring-out condition indicates that a Morris-Thorne-type wormhole can be maintained by violating the generalized null energy condition, and thus also breaking down the generalized weak, strong, and dominant energy conditions; meanwhile, analyses of the zero-tidal-force solution show that the standard null energy condition in general relativity can still be respected by the physical matter threading the wormhole. This way, the two topological effects have to dominate over the ordinary-matter source of gravity, and the scalar field is preferred to be noncanonical. By treating Brans-Dicke gravity as a reduced situation of Lovelock-Brans-Dicke gravity, we also examine the Brans-Dicke wormholes and energy conditions. |
1401.1599 | S. Q. Wu | Shuang-Qing Wu, Gao-Ming Deng, and Di Wu | Hawking radiation from rotating AdS black holes in conformal gravity | Latex, 12 pages, no figure | Astrophys. Space Sci. 352 (2014) 751-762 | 10.1007/s10509-014-1980-1 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend to study Hawking radiation via tunneling in conformal gravity. We
adopt Parikh-Wilczek's semi-classical tunneling method and the method of
complex-path integral to investigate Hawking radiation from new rotating AdS
black holes in conformal gravity. In this paper, the research on Hawking
radiation from the rotating black holes is done in a general system, not
limited in dragging coordinate systems any longer. Moreover, there existed some
shortcomings in the previous derivation of geodesic equations. Different from
the massless case, they used a different approach to derive the geodesic
equation of the massive particles. Even the treatment was inconsistent with the
variation principle of action. To remedy the shortcoming, we improve treatment
to deduce the geodesic equations of massive and massless particles in a unified
and self-consistent way. In addition, we also recover the Hawking temperature
resorting to the complex-path integral method.
| [
{
"created": "Wed, 8 Jan 2014 08:19:22 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Jul 2014 04:45:05 GMT",
"version": "v2"
}
] | 2014-07-23 | [
[
"Wu",
"Shuang-Qing",
""
],
[
"Deng",
"Gao-Ming",
""
],
[
"Wu",
"Di",
""
]
] | We extend to study Hawking radiation via tunneling in conformal gravity. We adopt Parikh-Wilczek's semi-classical tunneling method and the method of complex-path integral to investigate Hawking radiation from new rotating AdS black holes in conformal gravity. In this paper, the research on Hawking radiation from the rotating black holes is done in a general system, not limited in dragging coordinate systems any longer. Moreover, there existed some shortcomings in the previous derivation of geodesic equations. Different from the massless case, they used a different approach to derive the geodesic equation of the massive particles. Even the treatment was inconsistent with the variation principle of action. To remedy the shortcoming, we improve treatment to deduce the geodesic equations of massive and massless particles in a unified and self-consistent way. In addition, we also recover the Hawking temperature resorting to the complex-path integral method. |
gr-qc/0601031 | Kazuhiro Yamamoto | Kazuhiro Yamamoto, Shinji Miyoki, Takashi Uchiyama, Hideki Ishitsuka,
Masatake Ohashi, Kazuaki Kuroda, Takayuki Tomaru, Nobuaki Sato, Toshikazu
Suzuki, Tomiyoshi Haruyama, Akira Yamamoto, Takakazu Shintomi, Kenji Numata,
Koichi Waseda, Kazuhiko Ito, Koji Watanabe | Measurement of the mechanical loss of a cooled reflective coating for
gravitational wave detection | 8 pages, 6 figures, 3 tables : accepted version (by Physical Review
D) | Physical Review D 74, 022002 (2006) | 10.1103/PhysRevD.74.022002 | null | gr-qc cond-mat.mtrl-sci | null | We have measured the mechanical loss of a dielectric multilayer reflective
coating (ion-beam sputtered SiO$_2$ and Ta$_2$O$_5$) in cooled mirrors. The
loss was nearly independent of the temperature (4 K $\sim$ 300 K), frequency,
optical loss, and stress caused by the coating, and the details of the
manufacturing processes. The loss angle was $(4 \sim 6) \times 10^{-4}$. The
temperature independence of this loss implies that the amplitude of the coating
thermal noise, which is a severe limit in any precise measurement, is
proportional to the square root of the temperature. Sapphire mirrors at 20 K
satisfy the requirement concerning the thermal noise of even future
interferometric gravitational wave detector projects on the ground, for
example, LCGT.
| [
{
"created": "Sun, 8 Jan 2006 11:50:39 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Jul 2006 11:55:02 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Yamamoto",
"Kazuhiro",
""
],
[
"Miyoki",
"Shinji",
""
],
[
"Uchiyama",
"Takashi",
""
],
[
"Ishitsuka",
"Hideki",
""
],
[
"Ohashi",
"Masatake",
""
],
[
"Kuroda",
"Kazuaki",
""
],
[
"Tomaru",
"Takayuki",
""
... | We have measured the mechanical loss of a dielectric multilayer reflective coating (ion-beam sputtered SiO$_2$ and Ta$_2$O$_5$) in cooled mirrors. The loss was nearly independent of the temperature (4 K $\sim$ 300 K), frequency, optical loss, and stress caused by the coating, and the details of the manufacturing processes. The loss angle was $(4 \sim 6) \times 10^{-4}$. The temperature independence of this loss implies that the amplitude of the coating thermal noise, which is a severe limit in any precise measurement, is proportional to the square root of the temperature. Sapphire mirrors at 20 K satisfy the requirement concerning the thermal noise of even future interferometric gravitational wave detector projects on the ground, for example, LCGT. |
2305.17237 | Sara Saghafi | Kourosh Nozari, Sara Saghafi | Asymptotically locally flat and AdS higher-dimensional black holes of
Einstein-Horndeski-Maxwell gravity in the light of EHT observations: shadow
behavior and deflection angle | Accepted for publication in The European Physical Journal C, 31
pages, 14 figures | Eur. Phys. J. C, 83(07), 588 (2023) | 10.1140/epjc/s10052-023-11755-w | null | gr-qc astro-ph.HE hep-ph hep-th | http://creativecommons.org/licenses/by/4.0/ | Unification of gravity with other interactions, achieving the ultimate
framework of quantum gravity, and fundamental problems in particle physics and
cosmology motivate to consider extra spatial dimensions. The impact of these
extra dimensions on the modified theories of gravity has attracted a lot of
attention. One way to examine how extra dimensions affect the modified
gravitational theories is to analytically investigate astrophysical phenomena,
such as black hole shadows. In this study, we aim to investigate the behavior
of the shadow shapes of higher-dimensional charged black hole solutions
including asymptotically locally flat (ALF) and asymptotically locally AdS
(ALAdS) in Einstein-Horndeski-Maxwell (EHM) gravitational theory. We utilize
the Hamilton-Jacobi method to find photon orbits around these black holes as
well as the Carter approach to formulate the geodesic equations. We examine how
extra dimensions, negative cosmological constant, electric charge, and coupling
constants of the EHM gravity affect the shadow size of the black hole. Then, we
constrain these parameters by comparing the shadow radius of these black holes
with the shadow size of M87* supermassive black hole captured by the Event
Horizon Telescope (EHT) collaborations. We discover that generally the presence
of extra dimensions within the EHM gravity results in reducing the shadow size
of higher-dimensional ALF and ALAdS charged black holes, whereas the impact of
electric charge on the shadow of these black holes is suppressible....
| [
{
"created": "Fri, 26 May 2023 19:51:45 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Jun 2023 11:30:58 GMT",
"version": "v2"
}
] | 2023-07-12 | [
[
"Nozari",
"Kourosh",
""
],
[
"Saghafi",
"Sara",
""
]
] | Unification of gravity with other interactions, achieving the ultimate framework of quantum gravity, and fundamental problems in particle physics and cosmology motivate to consider extra spatial dimensions. The impact of these extra dimensions on the modified theories of gravity has attracted a lot of attention. One way to examine how extra dimensions affect the modified gravitational theories is to analytically investigate astrophysical phenomena, such as black hole shadows. In this study, we aim to investigate the behavior of the shadow shapes of higher-dimensional charged black hole solutions including asymptotically locally flat (ALF) and asymptotically locally AdS (ALAdS) in Einstein-Horndeski-Maxwell (EHM) gravitational theory. We utilize the Hamilton-Jacobi method to find photon orbits around these black holes as well as the Carter approach to formulate the geodesic equations. We examine how extra dimensions, negative cosmological constant, electric charge, and coupling constants of the EHM gravity affect the shadow size of the black hole. Then, we constrain these parameters by comparing the shadow radius of these black holes with the shadow size of M87* supermassive black hole captured by the Event Horizon Telescope (EHT) collaborations. We discover that generally the presence of extra dimensions within the EHM gravity results in reducing the shadow size of higher-dimensional ALF and ALAdS charged black holes, whereas the impact of electric charge on the shadow of these black holes is suppressible.... |
1310.4262 | Hongwei Yu | Jiawei Hu, Wenting Zhou, Hongwei Yu | Dynamics of an elementary quantum system outside a radiating
Schwarzschild black hole | a few typos corrected, a couple of references added, published
version | Phys. Rev. D 88, 085035 (2013) | 10.1103/PhysRevD.88.085035 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study, in the framework of open quantum systems, the dynamics of a
radially polarizable two-level atom in multi-polar coupling to fluctuating
vacuum electromagnetic fields which is placed at a fixed radial distance
outside a radiating Schwarzschild black hole, and analyze the transition rates
between atomic energy levels and the steady state the atom is driven to. We
find that the atom always thermalizes toward a steady state at an effective
temperature between zero and the Hawking temperature of the black hole.
Remarkably, the thermalization temperature depends on the transition frequency
of the atom, so that atoms with different transition frequencies essentially
thermalize to different temperatures. This counter-intuitive behavior is
however in close analogy to what happens for a two-level atom in a stationary
environment out of thermal equilibrium near a dielectric body of certain
geometry and dielectric permittivity. Our results thereby suggest in principle
a possible analogue system using engineered materials with certain desired
dielectric properties to verify features of Hawking radiation in lab-top
experiments.
| [
{
"created": "Wed, 16 Oct 2013 04:13:45 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Oct 2013 00:15:21 GMT",
"version": "v2"
}
] | 2013-10-30 | [
[
"Hu",
"Jiawei",
""
],
[
"Zhou",
"Wenting",
""
],
[
"Yu",
"Hongwei",
""
]
] | We study, in the framework of open quantum systems, the dynamics of a radially polarizable two-level atom in multi-polar coupling to fluctuating vacuum electromagnetic fields which is placed at a fixed radial distance outside a radiating Schwarzschild black hole, and analyze the transition rates between atomic energy levels and the steady state the atom is driven to. We find that the atom always thermalizes toward a steady state at an effective temperature between zero and the Hawking temperature of the black hole. Remarkably, the thermalization temperature depends on the transition frequency of the atom, so that atoms with different transition frequencies essentially thermalize to different temperatures. This counter-intuitive behavior is however in close analogy to what happens for a two-level atom in a stationary environment out of thermal equilibrium near a dielectric body of certain geometry and dielectric permittivity. Our results thereby suggest in principle a possible analogue system using engineered materials with certain desired dielectric properties to verify features of Hawking radiation in lab-top experiments. |
0710.0970 | Gamal Nashed G.L. | Gamal Gergess Lamee Nashed | Stability of Reissner Nordstr$\ddot{o}$m Black Hole | 10 pages, Latex | ActaPhys.Polon.a112:13,2007 | null | null | gr-qc | null | The singularity of the solutions obtained before in the teleparallel theory
of gravitation is studied. Also the stability of these solutions is studied
using the equations of geodesic deviation. The condition of stability is
obtained. From this condition the stability of Schwarzschild solution can be
obtained.
| [
{
"created": "Thu, 4 Oct 2007 10:18:42 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Nashed",
"Gamal Gergess Lamee",
""
]
] | The singularity of the solutions obtained before in the teleparallel theory of gravitation is studied. Also the stability of these solutions is studied using the equations of geodesic deviation. The condition of stability is obtained. From this condition the stability of Schwarzschild solution can be obtained. |
2212.05538 | Bernard Raffaelli | Bernard Raffaelli | The overtone level spacing of a black hole quasinormal frequencies: a
fingerprint of a local $SL(2,\mathbb{R})$ symmetry | 9 pages, preliminary version. arXiv admin note: text overlap with
arXiv:2112.12543 | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The imaginary part of the quasinormal frequencies spectrum for a static and
spherically symmetric black hole is analytically known to be equally spaced,
both for the highly damped and the weakly damped families of quasinormal modes.
Some interesting attempts have been made in the last twenty years to understand
in simple ways this level spacing for the only case of highly damped
quasinormal frequencies. Here, we show that the overtone level spacing, for
both the highly damped and weakly damped families of quasinormal modes, can
simply be understood as a fingerprint of a hidden local $SL(2,\mathbb{R})$
symmetry, near different regions of the black hole spacetime, i.e. the
near-horizon and the near-photon sphere regions.
| [
{
"created": "Sun, 11 Dec 2022 16:36:17 GMT",
"version": "v1"
}
] | 2022-12-13 | [
[
"Raffaelli",
"Bernard",
""
]
] | The imaginary part of the quasinormal frequencies spectrum for a static and spherically symmetric black hole is analytically known to be equally spaced, both for the highly damped and the weakly damped families of quasinormal modes. Some interesting attempts have been made in the last twenty years to understand in simple ways this level spacing for the only case of highly damped quasinormal frequencies. Here, we show that the overtone level spacing, for both the highly damped and weakly damped families of quasinormal modes, can simply be understood as a fingerprint of a hidden local $SL(2,\mathbb{R})$ symmetry, near different regions of the black hole spacetime, i.e. the near-horizon and the near-photon sphere regions. |
1206.1258 | Vishagan Sivanesan | Antonio Padilla and Vishagan Sivanesan | Boundary Terms and Junction Conditions for Generalized Scalar-Tensor
Theories | 13 pages, Equation corrected. Thanks to Tsutomu Kobayashi for
informing us of the typo | null | 10.1007/JHEP08(2012)122 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the boundary terms and junction conditions for Horndeski's
panoptic class of scalar-tensor theories, and write the bulk and boundary
equations of motion in explicitly second order form. We consider a number of
special subclasses, including galileon theories, and present the corresponding
formulae. Our analysis opens up of the possibility of studying tunnelling
between vacua in generalized scalar-tensor theories, and braneworld dynamics.
The latter follows because our results are independent of spacetime dimension.
| [
{
"created": "Wed, 6 Jun 2012 15:49:25 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Dec 2013 16:03:02 GMT",
"version": "v2"
}
] | 2015-06-05 | [
[
"Padilla",
"Antonio",
""
],
[
"Sivanesan",
"Vishagan",
""
]
] | We compute the boundary terms and junction conditions for Horndeski's panoptic class of scalar-tensor theories, and write the bulk and boundary equations of motion in explicitly second order form. We consider a number of special subclasses, including galileon theories, and present the corresponding formulae. Our analysis opens up of the possibility of studying tunnelling between vacua in generalized scalar-tensor theories, and braneworld dynamics. The latter follows because our results are independent of spacetime dimension. |
1602.02921 | Hamid Reza Sepangi | M. Khodadi, K. Nozari, H. R. Sepangi | More on the initial singularity problem in gravity's rainbow cosmology | 19 pages, 4 figures | Gen. Rel. Grav. 48 (2016) 166 | 10.1007/s10714-016-2160-0 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using a one-dimensional minisuperspace model with a dimensionless ratio
$\frac{E}{E_{Pl}}$, we study the initial singularity problem at the quantum
level for the closed rainbow cosmology with a homogeneous, isotropic classical
space-time background. We derive the classical Hamiltonian within the framework
of Schutz's formalism for an ideal fluid with a cosmological constant. We
characterize the behavior of the system at the early stages of the universe
evolution through analyzing the relevant shapes for the potential sector of the
classical Hamiltonian for various matter sources, each separately modified by
two rainbow functions. We show that for both rainbow universe models presented
here, there is the possibility of eliminating the initial singularity by
forming a potential barrier and static universe for a non-zero value of the
scale factor. We investigate their quantum stability and show that for an
energy-dependent space-time geometry with energies comparable with the Planck
energy, the non-zero value of the scale factor may be stable. It is shown that
under certain constraints the rainbow universe model filled with an exotic
matter as a domain wall fluid plus a cosmological constant can result in a
non-singular harmonic universe. In addition, we demonstrate that the
harmonically oscillating universe with respect to the scale factor is sensitive
to $\frac{E}{E_{Pl}}$ and that at high energies it may become stable quantum
mechanically. Through a Schr\"{o}dinger-Wheeler-De Witt (SWD) equation obtained
from the quantization of the classical Hamiltonian, we also extract the wave
packet of the universe with a focus on the early stages of the evolution.
| [
{
"created": "Tue, 9 Feb 2016 10:10:36 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Apr 2016 03:17:16 GMT",
"version": "v2"
},
{
"created": "Mon, 7 Nov 2016 05:53:28 GMT",
"version": "v3"
}
] | 2016-12-07 | [
[
"Khodadi",
"M.",
""
],
[
"Nozari",
"K.",
""
],
[
"Sepangi",
"H. R.",
""
]
] | Using a one-dimensional minisuperspace model with a dimensionless ratio $\frac{E}{E_{Pl}}$, we study the initial singularity problem at the quantum level for the closed rainbow cosmology with a homogeneous, isotropic classical space-time background. We derive the classical Hamiltonian within the framework of Schutz's formalism for an ideal fluid with a cosmological constant. We characterize the behavior of the system at the early stages of the universe evolution through analyzing the relevant shapes for the potential sector of the classical Hamiltonian for various matter sources, each separately modified by two rainbow functions. We show that for both rainbow universe models presented here, there is the possibility of eliminating the initial singularity by forming a potential barrier and static universe for a non-zero value of the scale factor. We investigate their quantum stability and show that for an energy-dependent space-time geometry with energies comparable with the Planck energy, the non-zero value of the scale factor may be stable. It is shown that under certain constraints the rainbow universe model filled with an exotic matter as a domain wall fluid plus a cosmological constant can result in a non-singular harmonic universe. In addition, we demonstrate that the harmonically oscillating universe with respect to the scale factor is sensitive to $\frac{E}{E_{Pl}}$ and that at high energies it may become stable quantum mechanically. Through a Schr\"{o}dinger-Wheeler-De Witt (SWD) equation obtained from the quantization of the classical Hamiltonian, we also extract the wave packet of the universe with a focus on the early stages of the evolution. |
0712.1429 | Ralf Schutzhold | Ralf Sch\"utzhold | Quantum back-reaction problems | 5 pages RevTeX, Proceedings to the workshop From Quantum to Emergent
Gravity: Theory and Phenomenology, June 11-15 2007, Trieste, Italy, published
in Proceedings of Science | PoSQG-Ph:036,2007 | null | null | gr-qc | null | The macroscopic behavior of many physical systems can be approximately
described by classical quantities. However, quantum theory demands the
existence of omnipresent quantum fluctuations on top of this classical
background -- which, albeit small, should have some impact onto its dynamics.
The correct treatment of this quantum back-reaction is one of the main problems
in quantum gravity and related to fundamental questions such as the initial
(big bang) singularity or the cosmological constant. By means of the
qualitative analogy between gravity and fluid dynamics, we try to shed some
light onto these problems and show some of the difficulties associated with the
calculation of the quantum back-reaction starting from the classical
(macroscopic) equation of motion.
| [
{
"created": "Mon, 10 Dec 2007 10:46:46 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Schützhold",
"Ralf",
""
]
] | The macroscopic behavior of many physical systems can be approximately described by classical quantities. However, quantum theory demands the existence of omnipresent quantum fluctuations on top of this classical background -- which, albeit small, should have some impact onto its dynamics. The correct treatment of this quantum back-reaction is one of the main problems in quantum gravity and related to fundamental questions such as the initial (big bang) singularity or the cosmological constant. By means of the qualitative analogy between gravity and fluid dynamics, we try to shed some light onto these problems and show some of the difficulties associated with the calculation of the quantum back-reaction starting from the classical (macroscopic) equation of motion. |
2407.17753 | Lakshmi J Naik | O. P. Jyothilakshmi, Lakshmi J. Naik, V. Sreekanth | Aspects of Rotating Anisotropic Dark Energy Stars | 10 pages, 12 figures, 1 table | null | null | null | gr-qc astro-ph.HE nucl-th | http://creativecommons.org/licenses/by/4.0/ | By employing modified Chaplygin fluid prescription for the dark energy, we
construct slowly rotating isotropic and anisotropic dark energy stars. The slow
rotation is incorporated via general relativistic Hartle-Thorne formalism;
whereas the anisotropy is introduced through Bowers-Liang prescription. We
consider both the monopole and quadrupole deformations and present a complete
analysis of rotating dark energy stars. By numerically solving the rotating
stellar structure equations in presence of anisotropy, we analyse and quantify
various properties of dark energy stars such as mass ($M$), radius, mass
deformation, angular momentum ($J$), moment of inertia, and quadrupole moment
($Q$), for three different equation of state parameters. We find that
anisotropic slow rotation results in significant deformation of stellar mass
and thereby affects other global properties studied. For the values of angular
frequencies considered, the effect of anisotropy on the stellar structure is
found to be more prominent than that due to rotation. The dimensionless
quadrupole moment $QM/J^2$ measuring deviation from a Kerr metric black hole
was obtained for anisotropic dark energy stars. We observe that dark energy
stars with higher anisotropic strength tend to approach the Kerr solution more
closely. We report that our results have considerable agreement with various
astrophysical observational measurements.
| [
{
"created": "Thu, 25 Jul 2024 04:08:19 GMT",
"version": "v1"
}
] | 2024-07-26 | [
[
"Jyothilakshmi",
"O. P.",
""
],
[
"Naik",
"Lakshmi J.",
""
],
[
"Sreekanth",
"V.",
""
]
] | By employing modified Chaplygin fluid prescription for the dark energy, we construct slowly rotating isotropic and anisotropic dark energy stars. The slow rotation is incorporated via general relativistic Hartle-Thorne formalism; whereas the anisotropy is introduced through Bowers-Liang prescription. We consider both the monopole and quadrupole deformations and present a complete analysis of rotating dark energy stars. By numerically solving the rotating stellar structure equations in presence of anisotropy, we analyse and quantify various properties of dark energy stars such as mass ($M$), radius, mass deformation, angular momentum ($J$), moment of inertia, and quadrupole moment ($Q$), for three different equation of state parameters. We find that anisotropic slow rotation results in significant deformation of stellar mass and thereby affects other global properties studied. For the values of angular frequencies considered, the effect of anisotropy on the stellar structure is found to be more prominent than that due to rotation. The dimensionless quadrupole moment $QM/J^2$ measuring deviation from a Kerr metric black hole was obtained for anisotropic dark energy stars. We observe that dark energy stars with higher anisotropic strength tend to approach the Kerr solution more closely. We report that our results have considerable agreement with various astrophysical observational measurements. |
gr-qc/0510109 | Alejandro Corichi | Alejandro Corichi, Jeronimo Cortez and Guillermo A. Mena Marugan | Unitary evolution in Gowdy cosmology | 5 pages, no figures. V2 discussion expanded, references added. Final
version to appear in PRD | Phys.Rev. D73 (2006) 041502 | 10.1103/PhysRevD.73.041502 | null | gr-qc hep-th | null | Recent results on the non-unitary character of quantum time evolution in the
family of Gowdy T**3 spacetimes bring the question of whether one should
renounce in cosmology to the most sacred principle of unitary evolution. In
this work we show that the answer is in the negative. We put forward a full
nonperturbative canonical quantization of the polarized Gowdy T**3 model that
implements the dynamics while preserving unitarity. We discuss possible
implications of this result.
| [
{
"created": "Tue, 25 Oct 2005 17:48:54 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Jan 2006 18:54:50 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Corichi",
"Alejandro",
""
],
[
"Cortez",
"Jeronimo",
""
],
[
"Marugan",
"Guillermo A. Mena",
""
]
] | Recent results on the non-unitary character of quantum time evolution in the family of Gowdy T**3 spacetimes bring the question of whether one should renounce in cosmology to the most sacred principle of unitary evolution. In this work we show that the answer is in the negative. We put forward a full nonperturbative canonical quantization of the polarized Gowdy T**3 model that implements the dynamics while preserving unitarity. We discuss possible implications of this result. |
1903.07543 | Justin Ripley | Justin L Ripley and Frans Pretorius | Gravitational Collapse in Einstein dilaton Gauss-Bonnet Gravity | 35 pages, 11 figures, edited to resemble journal version | null | 10.1088/1361-6382/ab2416 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present results from a numerical study of spherical gravitational collapse
in shift symmetric Einstein dilaton Gauss-Bonnet (EdGB) gravity. This modified
gravity theory has a single coupling parameter that when zero reduces to
general relativity (GR) minimally coupled to a massless scalar field. We first
show results from the weak EdGB coupling limit, where we obtain solutions that
smoothly approach those of the Einstein-Klein-Gordon system of GR. Here, in the
strong field case, though our code does not utilize horizon penetrating
coordinates, we nevertheless find tentative evidence that approaching black
hole formation the EdGB modifications cause the growth of scalar field "hair",
consistent with known static black hole solutions in EdGB gravity. For the
strong EdGB coupling regime, in a companion paper we first showed results that
even in the weak field (i.e. far from black hole formation), the EdGB equations
are of mixed type: evolution of the initially hyperbolic system of partial
differential equations lead to formation of a region where their character
changes to elliptic. Here, we present more details about this regime. In
particular, we show that an effective energy density based on the Misner-Sharp
mass is negative near these elliptic regions, and similarly the null
convergence condition is violated then.
| [
{
"created": "Mon, 18 Mar 2019 16:28:22 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Oct 2019 12:46:50 GMT",
"version": "v2"
}
] | 2019-10-16 | [
[
"Ripley",
"Justin L",
""
],
[
"Pretorius",
"Frans",
""
]
] | We present results from a numerical study of spherical gravitational collapse in shift symmetric Einstein dilaton Gauss-Bonnet (EdGB) gravity. This modified gravity theory has a single coupling parameter that when zero reduces to general relativity (GR) minimally coupled to a massless scalar field. We first show results from the weak EdGB coupling limit, where we obtain solutions that smoothly approach those of the Einstein-Klein-Gordon system of GR. Here, in the strong field case, though our code does not utilize horizon penetrating coordinates, we nevertheless find tentative evidence that approaching black hole formation the EdGB modifications cause the growth of scalar field "hair", consistent with known static black hole solutions in EdGB gravity. For the strong EdGB coupling regime, in a companion paper we first showed results that even in the weak field (i.e. far from black hole formation), the EdGB equations are of mixed type: evolution of the initially hyperbolic system of partial differential equations lead to formation of a region where their character changes to elliptic. Here, we present more details about this regime. In particular, we show that an effective energy density based on the Misner-Sharp mass is negative near these elliptic regions, and similarly the null convergence condition is violated then. |
1411.5203 | Zacharias Roupas | Zacharias Roupas | Thermal Mass limit of Neutron Cores | 8 pages, 8 figures, minor changes to match published version | Phys. Rev. D 91, 023001 (2015) | 10.1103/PhysRevD.91.023001 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Static thermal equilibrium of a quantum self-gravitating ideal gas in general
relativity is studied at any temperature, taking into account the
Tolman-Ehrenfest effect. Thermal contribution to the gravitational stability of
static neutron cores is quantified. The curve of maximum mass with respect to
temperature is reported. At low temperatures the Oppenheimer-Volkoff
calculation is recovered, while at high temperatures the recently reported
classical gas calculation is recovered. An ultimate upper mass limit $M =
2.43M_\odot$ of all maximum values is found to occur at Tolman temperature $ T
= 1.27mc^2$ with radius $R = 15.2km$.
| [
{
"created": "Wed, 19 Nov 2014 12:43:41 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Jan 2015 17:50:37 GMT",
"version": "v2"
}
] | 2015-01-08 | [
[
"Roupas",
"Zacharias",
""
]
] | Static thermal equilibrium of a quantum self-gravitating ideal gas in general relativity is studied at any temperature, taking into account the Tolman-Ehrenfest effect. Thermal contribution to the gravitational stability of static neutron cores is quantified. The curve of maximum mass with respect to temperature is reported. At low temperatures the Oppenheimer-Volkoff calculation is recovered, while at high temperatures the recently reported classical gas calculation is recovered. An ultimate upper mass limit $M = 2.43M_\odot$ of all maximum values is found to occur at Tolman temperature $ T = 1.27mc^2$ with radius $R = 15.2km$. |
1706.06311 | Richard Brito | Richard Brito, Shrobana Ghosh, Enrico Barausse, Emanuele Berti, Vitor
Cardoso, Irina Dvorkin, Antoine Klein, Paolo Pani | Gravitational wave searches for ultralight bosons with LIGO and LISA | 23 pages, 14 Figures, 4 Tables; v2: references added, small changes
to match version published in Physical Review D | Phys. Rev. D 96, 064050 (2017) | 10.1103/PhysRevD.96.064050 | null | gr-qc astro-ph.HE hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Ultralight bosons can induce superradiant instabilities in spinning black
holes, tapping their rotational energy to trigger the growth of a bosonic
condensate. Possible observational imprints of these boson clouds include (i)
direct detection of the nearly monochromatic (resolvable or stochastic)
gravitational waves emitted by the condensate, and (ii) statistically
significant evidence for the formation of "holes" at large spins in the spin
versus mass plane (sometimes also referred to as "Regge plane") of
astrophysical black holes. In this work, we focus on the prospects of LISA and
LIGO detecting or constraining scalars with mass in the range $m_s\in
[10^{-19},\,10^{-15}]$ eV and $m_s\in [10^{-14},\,10^{-11}]$ eV, respectively.
Using astrophysical models of black-hole populations calibrated to observations
and black-hole perturbation theory calculations of the gravitational emission,
we find that, in optimistic scenarios, LIGO could observe a stochastic
background of gravitational radiation in the range $m_s\in [2\times 10^{-13},
10^{-12}]$ eV, and up to $10^4$ resolvable events in a $4$-year search if
$m_s\sim 3\times 10^{-13}\,{\rm eV}$. LISA could observe a stochastic
background for boson masses in the range $m_s\in [5\times 10^{-19}, 5\times
10^{-16}]$, and up to $\sim 10^3$ resolvable events in a $4$-year search if
$m_s\sim 10^{-17}\,{\rm eV}$. LISA could further measure spins for black-hole
binaries with component masses in the range $[10^3, 10^7]~M_\odot$, which is
not probed by traditional spin-measurement techniques. A statistical analysis
of the spin distribution of these binaries could either rule out scalar fields
in the mass range $\sim [4 \times 10^{-18}, 10^{-14}]$ eV, or measure $m_s$
with ten percent accuracy if light scalars in the mass range $\sim [10^{-17},
10^{-13}]$ eV exist.
| [
{
"created": "Tue, 20 Jun 2017 08:27:59 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Oct 2017 14:42:49 GMT",
"version": "v2"
}
] | 2017-10-05 | [
[
"Brito",
"Richard",
""
],
[
"Ghosh",
"Shrobana",
""
],
[
"Barausse",
"Enrico",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Dvorkin",
"Irina",
""
],
[
"Klein",
"Antoine",
""
],
[
... | Ultralight bosons can induce superradiant instabilities in spinning black holes, tapping their rotational energy to trigger the growth of a bosonic condensate. Possible observational imprints of these boson clouds include (i) direct detection of the nearly monochromatic (resolvable or stochastic) gravitational waves emitted by the condensate, and (ii) statistically significant evidence for the formation of "holes" at large spins in the spin versus mass plane (sometimes also referred to as "Regge plane") of astrophysical black holes. In this work, we focus on the prospects of LISA and LIGO detecting or constraining scalars with mass in the range $m_s\in [10^{-19},\,10^{-15}]$ eV and $m_s\in [10^{-14},\,10^{-11}]$ eV, respectively. Using astrophysical models of black-hole populations calibrated to observations and black-hole perturbation theory calculations of the gravitational emission, we find that, in optimistic scenarios, LIGO could observe a stochastic background of gravitational radiation in the range $m_s\in [2\times 10^{-13}, 10^{-12}]$ eV, and up to $10^4$ resolvable events in a $4$-year search if $m_s\sim 3\times 10^{-13}\,{\rm eV}$. LISA could observe a stochastic background for boson masses in the range $m_s\in [5\times 10^{-19}, 5\times 10^{-16}]$, and up to $\sim 10^3$ resolvable events in a $4$-year search if $m_s\sim 10^{-17}\,{\rm eV}$. LISA could further measure spins for black-hole binaries with component masses in the range $[10^3, 10^7]~M_\odot$, which is not probed by traditional spin-measurement techniques. A statistical analysis of the spin distribution of these binaries could either rule out scalar fields in the mass range $\sim [4 \times 10^{-18}, 10^{-14}]$ eV, or measure $m_s$ with ten percent accuracy if light scalars in the mass range $\sim [10^{-17}, 10^{-13}]$ eV exist. |
gr-qc/0508012 | Lorenzo Iorio | Lorenzo Iorio | On the impossibility of using certain existing spacecraft for the
measurement of the Lense-Thirring effect in the terrestrial gravitational
field | LaTex2e, 13 pages, no figures, no tables, 31 references. Reference
added, Section 2.4 added | null | null | null | gr-qc astro-ph physics.space-ph | null | In the context of the currently ongoing efforts to improve the accuracy and
reliability of the measurement of the Lense-Thirring effect in the
gravitational field of the Earth it has recently been proposed to use the data
from the existing spacecraft endowed with some active mechanisms of
compensation of the non-gravitational accelerations like GRACE. In this paper
we critically discuss this interesting possibility. Unfortunately, it turns out
to be unpracticable because of the impact of the uncancelled even zonal
harmonic coefficients of the multipolar expansion of the terrestrial
gravitational potential and of some time-dependent tidal perturbations which
would resemble as superimposed linear trends over the necessarily limited
observational time span of the analysis.
| [
{
"created": "Tue, 2 Aug 2005 17:31:00 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Aug 2005 13:41:09 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Iorio",
"Lorenzo",
""
]
] | In the context of the currently ongoing efforts to improve the accuracy and reliability of the measurement of the Lense-Thirring effect in the gravitational field of the Earth it has recently been proposed to use the data from the existing spacecraft endowed with some active mechanisms of compensation of the non-gravitational accelerations like GRACE. In this paper we critically discuss this interesting possibility. Unfortunately, it turns out to be unpracticable because of the impact of the uncancelled even zonal harmonic coefficients of the multipolar expansion of the terrestrial gravitational potential and of some time-dependent tidal perturbations which would resemble as superimposed linear trends over the necessarily limited observational time span of the analysis. |
gr-qc/0003035 | Richard J. Epp | Richard J. Epp (Raman Research Institute, India) | Angular momentum and an invariant quasilocal energy in general
relativity | 54 pages LaTeX, no figures, includes brief summary of results,
submitted to Physical Review D | Phys.Rev. D62 (2000) 124018 | 10.1103/PhysRevD.62.124018 | null | gr-qc | null | Owing to its transformation property under local boosts, the Brown-York
quasilocal energy surface density is the analogue of E in the special
relativity formula: E^2-p^2=m^2. In this paper I will motivate the general
relativistic version of this formula, and thereby arrive at a geometrically
natural definition of an `invariant quasilocal energy', or IQE. In analogy with
the invariant mass m, the IQE is invariant under local boosts of the set of
observers on a given two-surface S in spacetime. A reference energy subtraction
procedure is required, but in contrast to the Brown-York procedure, S is
isometrically embedded into a four-dimensional reference spacetime. This
virtually eliminates the embeddability problem inherent in the use of a
three-dimensional reference space, but introduces a new one: such embeddings
are not unique, leading to an ambiguity in the reference IQE. However, in this
codimension-two setting there are two curvatures associated with S: the
curvatures of its tangent and normal bundles. Taking advantage of this fact, I
will suggest a possible way to resolve the embedding ambiguity, which at the
same time will be seen to incorporate angular momentum into the energy at the
quasilocal level. I will analyze the IQE in the following cases: both the
spatial and future null infinity limits of a large sphere in asymptotically
flat spacetimes; a small sphere shrinking toward a point along either spatial
or null directions; and finally, in asymptotically anti-de Sitter spacetimes.
The last case reveals a striking similarity between the reference IQE and a
certain counterterm energy recently proposed in the context of the conjectured
AdS/CFT correspondence.
| [
{
"created": "Wed, 8 Mar 2000 21:42:03 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Epp",
"Richard J.",
"",
"Raman Research Institute, India"
]
] | Owing to its transformation property under local boosts, the Brown-York quasilocal energy surface density is the analogue of E in the special relativity formula: E^2-p^2=m^2. In this paper I will motivate the general relativistic version of this formula, and thereby arrive at a geometrically natural definition of an `invariant quasilocal energy', or IQE. In analogy with the invariant mass m, the IQE is invariant under local boosts of the set of observers on a given two-surface S in spacetime. A reference energy subtraction procedure is required, but in contrast to the Brown-York procedure, S is isometrically embedded into a four-dimensional reference spacetime. This virtually eliminates the embeddability problem inherent in the use of a three-dimensional reference space, but introduces a new one: such embeddings are not unique, leading to an ambiguity in the reference IQE. However, in this codimension-two setting there are two curvatures associated with S: the curvatures of its tangent and normal bundles. Taking advantage of this fact, I will suggest a possible way to resolve the embedding ambiguity, which at the same time will be seen to incorporate angular momentum into the energy at the quasilocal level. I will analyze the IQE in the following cases: both the spatial and future null infinity limits of a large sphere in asymptotically flat spacetimes; a small sphere shrinking toward a point along either spatial or null directions; and finally, in asymptotically anti-de Sitter spacetimes. The last case reveals a striking similarity between the reference IQE and a certain counterterm energy recently proposed in the context of the conjectured AdS/CFT correspondence. |
2002.09208 | Yorgo Senikoglu | Tekin Dereli and Yorgo Senikoglu | A non-minimally coupled, conformally extended Einstein-Maxwell theory of
pp-waves | Title changed, some references added. Matches the published version | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A non-minimal coupling of Weyl curvatures to electromagnetic fields is
considered in Brans-Dicke-Maxwell theory. The gravitational field equations are
formulated in a Riemannian spacetime where the spacetime torsion is constrained
to zero by the method of Lagrange multipliers in the language of exterior
differential forms. The significance and ramifications of non-minimal couplings
to gravity are examined in a pp-wave spacetime.
| [
{
"created": "Fri, 21 Feb 2020 10:30:06 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Apr 2020 07:27:29 GMT",
"version": "v2"
}
] | 2020-04-14 | [
[
"Dereli",
"Tekin",
""
],
[
"Senikoglu",
"Yorgo",
""
]
] | A non-minimal coupling of Weyl curvatures to electromagnetic fields is considered in Brans-Dicke-Maxwell theory. The gravitational field equations are formulated in a Riemannian spacetime where the spacetime torsion is constrained to zero by the method of Lagrange multipliers in the language of exterior differential forms. The significance and ramifications of non-minimal couplings to gravity are examined in a pp-wave spacetime. |
2002.05177 | Josu Aurrekoetxea | Josu C. Aurrekoetxea, Thomas Helfer, Eugene A. Lim | Coherent Gravitational Waveforms and Memory from Cosmic String Loops | 15 pages, 16 figures, 2 YouTube movies: https://youtu.be/-dhYA2788LA
https://youtu.be/0sSH54gXu4U | null | 10.1088/1361-6382/aba28b | KCL-PH-TH/2020-06 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct, for the first time, the time-domain gravitational wave strain
waveform from the collapse of a strongly gravitating Abelian Higgs cosmic
string loop in full general relativity. We show that the strain exhibits a
large memory effect during merger, ending with a burst and the characteristic
ringdown as a black hole is formed. Furthermore, we investigate the waveform
and energy emitted as a function of string width, loop radius and string
tension $G\mu$. We find that the mass normalized gravitational wave energy
displays a strong dependence on the inverse of the string tension
$E_{\mathrm{GW}}/M_0\propto 1/G\mu$, with $E_{\mathrm{GW}}/M_0 \sim {\cal
O}(1)\%$ at the percent level, for the regime where $G\mu\gtrsim10^{-3}$.
Conversely, we show that the efficiency is only weakly dependent on the initial
string width and initial loop radii. Using these results, we argue that
gravitational wave production is dominated by kinematical instead of
geometrical considerations.
| [
{
"created": "Wed, 12 Feb 2020 19:02:44 GMT",
"version": "v1"
},
{
"created": "Fri, 18 Sep 2020 09:06:45 GMT",
"version": "v2"
}
] | 2020-10-28 | [
[
"Aurrekoetxea",
"Josu C.",
""
],
[
"Helfer",
"Thomas",
""
],
[
"Lim",
"Eugene A.",
""
]
] | We construct, for the first time, the time-domain gravitational wave strain waveform from the collapse of a strongly gravitating Abelian Higgs cosmic string loop in full general relativity. We show that the strain exhibits a large memory effect during merger, ending with a burst and the characteristic ringdown as a black hole is formed. Furthermore, we investigate the waveform and energy emitted as a function of string width, loop radius and string tension $G\mu$. We find that the mass normalized gravitational wave energy displays a strong dependence on the inverse of the string tension $E_{\mathrm{GW}}/M_0\propto 1/G\mu$, with $E_{\mathrm{GW}}/M_0 \sim {\cal O}(1)\%$ at the percent level, for the regime where $G\mu\gtrsim10^{-3}$. Conversely, we show that the efficiency is only weakly dependent on the initial string width and initial loop radii. Using these results, we argue that gravitational wave production is dominated by kinematical instead of geometrical considerations. |
1903.11425 | Silvia Pla Garc\'ia | Antonio Ferreiro, Jose Navarro-Salas and Silvia Pla | Pair creation in electric fields, renormalization, and backreaction | 6 pages. Contribution to the Marcel Grossmann Meeting 2018 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider pair production phenomena in spatially homogeneous strong
electric fields. We focus on spinor QED in two-dimensions and discuss the
potential ambiguity in the adiabatic order assignment for the electromagnetic
potential required to fix the renormalization subtractions. This ambiguity can
be univocally fixed by imposing, at the semiclassical level, stress-energy
conservation when both electric and gravitational backgrounds are present.
| [
{
"created": "Wed, 27 Mar 2019 13:48:59 GMT",
"version": "v1"
}
] | 2019-03-28 | [
[
"Ferreiro",
"Antonio",
""
],
[
"Navarro-Salas",
"Jose",
""
],
[
"Pla",
"Silvia",
""
]
] | We consider pair production phenomena in spatially homogeneous strong electric fields. We focus on spinor QED in two-dimensions and discuss the potential ambiguity in the adiabatic order assignment for the electromagnetic potential required to fix the renormalization subtractions. This ambiguity can be univocally fixed by imposing, at the semiclassical level, stress-energy conservation when both electric and gravitational backgrounds are present. |
1207.4689 | Christian Roeken | Christian R\"oken | On the Nature of Black Holes in Loop Quantum Gravity | null | Class. Quantum Grav. 30 (2013) 015005 | 10.1088/0264-9381/30/1/015005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A genuine notion of black holes can only be obtained in the fundamental
framework of quantum gravity resolving the curvature singularities and giving
an account of the statistical mechanical, microscopic degrees of freedom able
to explain the black hole thermodynamical properties. As for all quantum
systems, a quantum realization of black holes requires an operator algebra of
the fundamental observables of the theory which is introduced in this study
based on aspects of loop quantum gravity. From the eigenvalue spectra of the
quantum operators for the black hole area, charge and angular momentum, it is
demonstrated that a strict bound on the extensive parameters, different from
the relation arising in classical general relativity, holds, implying that the
extremal black hole state can neither be measured nor can its existence be
proven. This is, as turns out, a result of the specific form of the chosen
angular momentum operator and the corresponding eigenvalue spectrum, or rather
the quantum measurement process of angular momentum. Quantum mechanical
considerations and the lowest, non-zero eigenvalue of the loop quantum gravity
black hole mass spectrum indicate, on the one hand, a physical Planck scale
cutoff of the Hawking temperature law and, on the other hand, give upper and
lower bounds on the numerical value of the Immirzi parameter. This analysis
provides an approximative description of the behavior and the nature of quantum
black holes.
| [
{
"created": "Thu, 19 Jul 2012 14:39:55 GMT",
"version": "v1"
},
{
"created": "Wed, 15 Aug 2012 09:10:42 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Oct 2012 13:03:28 GMT",
"version": "v3"
}
] | 2015-06-05 | [
[
"Röken",
"Christian",
""
]
] | A genuine notion of black holes can only be obtained in the fundamental framework of quantum gravity resolving the curvature singularities and giving an account of the statistical mechanical, microscopic degrees of freedom able to explain the black hole thermodynamical properties. As for all quantum systems, a quantum realization of black holes requires an operator algebra of the fundamental observables of the theory which is introduced in this study based on aspects of loop quantum gravity. From the eigenvalue spectra of the quantum operators for the black hole area, charge and angular momentum, it is demonstrated that a strict bound on the extensive parameters, different from the relation arising in classical general relativity, holds, implying that the extremal black hole state can neither be measured nor can its existence be proven. This is, as turns out, a result of the specific form of the chosen angular momentum operator and the corresponding eigenvalue spectrum, or rather the quantum measurement process of angular momentum. Quantum mechanical considerations and the lowest, non-zero eigenvalue of the loop quantum gravity black hole mass spectrum indicate, on the one hand, a physical Planck scale cutoff of the Hawking temperature law and, on the other hand, give upper and lower bounds on the numerical value of the Immirzi parameter. This analysis provides an approximative description of the behavior and the nature of quantum black holes. |
2112.06758 | Fabian L\'aszl\'o Konstantin Wagner | Fabian Wagner | Towards quantum Mechanics on the curved cotangent bundle | 18 pages. v3: version accepted for publication in CQG, some
paragraphs added, minor modifications to v2; v2: major changes - much more
streamlined and rigorous derivation and new results in comparison to v1 | null | 10.1088/1361-6382/ad1c36 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The minimal-length paradigm is a cornerstone of quantum gravity
phenomenology. Recently, it has been demonstrated that minimal-length quantum
mechanics can alternatively be described as an undeformed theory set on a
nontrivial momentum space. However, there is no fully consistent formulation of
these theories beyond Cartesian coordinates in flat space and, in particular,
no position representation. This paper is intended to take the first steps in
bridging this gap. We find a natural position representation of the position
and momentum operators on general curved cotangent bundles. In an expansion
akin to Riemann normal coordinates with curvature in both position and momentum
space, we apply the formalism perturbatively to the isotropic harmonic
oscillator and the hydrogenic atom. Due to the symmetry of the harmonic
oscillator under exchange of positions and momenta, we show that it is
impossible to distinguish position- from momentum- space curvature with
oscillators alone. Thus, we obtain an instantiation of Born reciprocity on the
curved cotangent bundle, i. e. in precisely the way Born originally envisioned.
It manifests itself as a symmetry mixing UV and IR physics, reminiscent of
T-duality in string theory.
| [
{
"created": "Mon, 13 Dec 2021 16:08:19 GMT",
"version": "v1"
},
{
"created": "Tue, 21 Dec 2021 13:35:34 GMT",
"version": "v2"
},
{
"created": "Thu, 3 Feb 2022 17:43:13 GMT",
"version": "v3"
},
{
"created": "Thu, 11 Jan 2024 15:06:48 GMT",
"version": "v4"
}
] | 2024-01-12 | [
[
"Wagner",
"Fabian",
""
]
] | The minimal-length paradigm is a cornerstone of quantum gravity phenomenology. Recently, it has been demonstrated that minimal-length quantum mechanics can alternatively be described as an undeformed theory set on a nontrivial momentum space. However, there is no fully consistent formulation of these theories beyond Cartesian coordinates in flat space and, in particular, no position representation. This paper is intended to take the first steps in bridging this gap. We find a natural position representation of the position and momentum operators on general curved cotangent bundles. In an expansion akin to Riemann normal coordinates with curvature in both position and momentum space, we apply the formalism perturbatively to the isotropic harmonic oscillator and the hydrogenic atom. Due to the symmetry of the harmonic oscillator under exchange of positions and momenta, we show that it is impossible to distinguish position- from momentum- space curvature with oscillators alone. Thus, we obtain an instantiation of Born reciprocity on the curved cotangent bundle, i. e. in precisely the way Born originally envisioned. It manifests itself as a symmetry mixing UV and IR physics, reminiscent of T-duality in string theory. |
1603.05836 | Paingalil Kunjan Suresh | N. Malsawmtluangi and P. K. Suresh | BB mode angular power spectrum of CMB from massive gravity | 11 pages, 7 figures | Astrophysics and Space Science, Vol 366, 113 (2021) | 10.1007/s10509-021-04017-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The BB-mode correlation angular power spectrum of CMB is studied for
primordial massive gravitational waves for several inflation models. The
comparative study of the angular power spectrum with the joint BICEP2/Keck
Array and Planck data suggests further constraint on the lower and upper bounds
on the mass of primordial gravitons. Assuming a modified dispersion relation,
the mass of primordial graviton is also calculated. The resulting constraint
also agrees with other theoretical estimates.
| [
{
"created": "Fri, 18 Mar 2016 11:04:34 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Nov 2021 06:25:08 GMT",
"version": "v2"
}
] | 2021-11-29 | [
[
"Malsawmtluangi",
"N.",
""
],
[
"Suresh",
"P. K.",
""
]
] | The BB-mode correlation angular power spectrum of CMB is studied for primordial massive gravitational waves for several inflation models. The comparative study of the angular power spectrum with the joint BICEP2/Keck Array and Planck data suggests further constraint on the lower and upper bounds on the mass of primordial gravitons. Assuming a modified dispersion relation, the mass of primordial graviton is also calculated. The resulting constraint also agrees with other theoretical estimates. |
1812.05564 | Jose Navarro-Salas | Antonio Ferreiro and Jose Navarro-Salas | Running couplings from adiabatic regularization | Revised version. Some points clarified. New references added. 6
pages. To appear in Phys. Lett. B | null | 10.1016/j.physletb.2019.03.026 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend the adiabatic regularization method by introducing an arbitrary
mass scale $\mu$ in the construction of the subtraction terms. This allows us
to obtain, in a very robust way, the running of the coupling constants by
demanding $\mu$-invariance of the effective semiclassical (Maxwell-Einstein)
equations. In particular, we get the running of the electric charge of
perturbative quantum electrodynamics. Furthermore, the method brings about a
renormalization of the cosmological constant and the Newtonian gravitational
constant. The running obtained for these dimensionful coupling constants has
new relevant (non-logarithmic) contributions, not predicted by dimensional
regularization.
| [
{
"created": "Thu, 13 Dec 2018 18:32:26 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Mar 2019 07:16:07 GMT",
"version": "v2"
}
] | 2019-03-27 | [
[
"Ferreiro",
"Antonio",
""
],
[
"Navarro-Salas",
"Jose",
""
]
] | We extend the adiabatic regularization method by introducing an arbitrary mass scale $\mu$ in the construction of the subtraction terms. This allows us to obtain, in a very robust way, the running of the coupling constants by demanding $\mu$-invariance of the effective semiclassical (Maxwell-Einstein) equations. In particular, we get the running of the electric charge of perturbative quantum electrodynamics. Furthermore, the method brings about a renormalization of the cosmological constant and the Newtonian gravitational constant. The running obtained for these dimensionful coupling constants has new relevant (non-logarithmic) contributions, not predicted by dimensional regularization. |
2011.03828 | Vasilis Oikonomou | V.K. Oikonomou, F.P. Fronimos | Non-minimally Coupled Einstein-Gauss-Bonnet Gravity with Massless
Gravitons: The Constant-roll Case | Invited publication for the EPJP special issue Modified Gravity
Theories and Cosmology | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this letter we study the behavior of non-minimally coupled
Einstein-Gauss-Bonnet gravity theories with the constant-roll condition.
Recalling the results of the striking GW170817 event, we demand that the
velocity of the gravitational waves is equated to unity in natural units,
meaning that $c_T^2=1$. This is a powerful restriction since it leads to a
decrease in the degrees of freedom and subsequently reveals a connection
between the scalar functions of the theory which presumably have different
origins. In this framework, we shall assume that a scalar potential is present
and can be extracted easily from the equations of motion by simply designating
the scalar coupling functions. Obviously, a different approach is feasible but
such choice will prove to be extremely convenient. Afterwards, we impose
certain approximations in order to facilitate our study. Each assumption is
capable of producing different phenomenology so a summary of all the possible
configurations for Hubble's parameter, its derivative and the scalar potential
along with the corresponding assumptions are present at the end of the paper.
We show that compatibility under the constant-roll assumption can be achieved
for a variety of model functions and different approaches, although one must
always be aware of the imposed approximations since the possibility of a model
producing viable results while simultaneously violating even a single
approximation exists. Finally, in the end, a new formalism which leads to a
plethora of convenient coupling functions according to the readers choice is
presented. Utilizing such formalism may lead to new cases for coupling
functions which have not been used yet, but are in fact able of producing
viable phenomenology for the inflationary era.
| [
{
"created": "Sat, 7 Nov 2020 18:40:45 GMT",
"version": "v1"
}
] | 2020-11-10 | [
[
"Oikonomou",
"V. K.",
""
],
[
"Fronimos",
"F. P.",
""
]
] | In this letter we study the behavior of non-minimally coupled Einstein-Gauss-Bonnet gravity theories with the constant-roll condition. Recalling the results of the striking GW170817 event, we demand that the velocity of the gravitational waves is equated to unity in natural units, meaning that $c_T^2=1$. This is a powerful restriction since it leads to a decrease in the degrees of freedom and subsequently reveals a connection between the scalar functions of the theory which presumably have different origins. In this framework, we shall assume that a scalar potential is present and can be extracted easily from the equations of motion by simply designating the scalar coupling functions. Obviously, a different approach is feasible but such choice will prove to be extremely convenient. Afterwards, we impose certain approximations in order to facilitate our study. Each assumption is capable of producing different phenomenology so a summary of all the possible configurations for Hubble's parameter, its derivative and the scalar potential along with the corresponding assumptions are present at the end of the paper. We show that compatibility under the constant-roll assumption can be achieved for a variety of model functions and different approaches, although one must always be aware of the imposed approximations since the possibility of a model producing viable results while simultaneously violating even a single approximation exists. Finally, in the end, a new formalism which leads to a plethora of convenient coupling functions according to the readers choice is presented. Utilizing such formalism may lead to new cases for coupling functions which have not been used yet, but are in fact able of producing viable phenomenology for the inflationary era. |
2301.08200 | Micha{\l} Zawada | M. Naro\.znik, M. Bober, M. Zawada | Optical ultra-stable optical clock cavities as resonant mass
gravitational wave detectors in search for new physics | null | null | 10.1016/j.physletb.2023.138260 | null | gr-qc astro-ph.HE physics.atom-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose to use table-top-size ultra-stable optical cavities from the
state-of-the-art optical atomic clocks as bar gravitational wave detectors for
the frequencies higher than 2 kHz. We show that 2-20 kHz range of gravitational
waves' spectrum can be accessed with instruments below 2 meters in size. The
proposed cavities' materials and properties are being within the present-day
technology grasp. The ultra-stable optical cavities allow detecting not only
predicted gravitational wave signals from such sources as binary neutron star
mergers and post-mergers, subsolar-mass primordial black-hole mergers, and
collapsing stellar cores, but can reach new physics beyond standard model
looking for ultralight bosons such as QCD axions and axion-like particles
formed through black hole superradiance.
| [
{
"created": "Thu, 19 Jan 2023 17:52:16 GMT",
"version": "v1"
}
] | 2023-11-27 | [
[
"Narożnik",
"M.",
""
],
[
"Bober",
"M.",
""
],
[
"Zawada",
"M.",
""
]
] | We propose to use table-top-size ultra-stable optical cavities from the state-of-the-art optical atomic clocks as bar gravitational wave detectors for the frequencies higher than 2 kHz. We show that 2-20 kHz range of gravitational waves' spectrum can be accessed with instruments below 2 meters in size. The proposed cavities' materials and properties are being within the present-day technology grasp. The ultra-stable optical cavities allow detecting not only predicted gravitational wave signals from such sources as binary neutron star mergers and post-mergers, subsolar-mass primordial black-hole mergers, and collapsing stellar cores, but can reach new physics beyond standard model looking for ultralight bosons such as QCD axions and axion-like particles formed through black hole superradiance. |
gr-qc/0609084 | Kirill Bronnikov | K.A. Bronnikov, M.S. Chernakova, J.C. Fabris, N. Pinto-Neto, M.E.
Rodrigues | Cold black holes and conformal continuations | 15 pages, latex | Int.J.Mod.Phys.D17:25-42,2008 | 10.1142/S0218271808011845 | null | gr-qc | null | We study Einstein gravity minimally coupled to a scalar field in a static,
spherically symmetric space-time in four dimensions. Black hole solutions are
shown to exist for a phantom scalar field whose kinetic energy is negative.
These ``scalar black holes'' have an infinite horizon area and zero Hawking
temperature and are termed ``cold black holes'' (CBHs). The relevant explicit
solutions are well-known in the massless case (the so-called anti-Fisher
solution), and we have found a particular example of a CBH with a nonzero
potential $V(\phi)$. All CBHs with $V(\phi) \not \equiv 0$ are shown to behave
near the horizon quite similarly to those with a massless field. The above
solutions can be converted by a conformal transformation to Jordan frames of a
general class of scalar-tensor theories of gravity, but CBH horizons in one
frame are in many cases converted to singularities in the other, which gives
rise to a new type of conformal continuation.
| [
{
"created": "Wed, 20 Sep 2006 18:12:36 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Bronnikov",
"K. A.",
""
],
[
"Chernakova",
"M. S.",
""
],
[
"Fabris",
"J. C.",
""
],
[
"Pinto-Neto",
"N.",
""
],
[
"Rodrigues",
"M. E.",
""
]
] | We study Einstein gravity minimally coupled to a scalar field in a static, spherically symmetric space-time in four dimensions. Black hole solutions are shown to exist for a phantom scalar field whose kinetic energy is negative. These ``scalar black holes'' have an infinite horizon area and zero Hawking temperature and are termed ``cold black holes'' (CBHs). The relevant explicit solutions are well-known in the massless case (the so-called anti-Fisher solution), and we have found a particular example of a CBH with a nonzero potential $V(\phi)$. All CBHs with $V(\phi) \not \equiv 0$ are shown to behave near the horizon quite similarly to those with a massless field. The above solutions can be converted by a conformal transformation to Jordan frames of a general class of scalar-tensor theories of gravity, but CBH horizons in one frame are in many cases converted to singularities in the other, which gives rise to a new type of conformal continuation. |
0806.0034 | Gonzalo Olmo | Ivan Agullo, Jose Navarro-Salas, Gonzalo J. Olmo, Leonard Parker | The Power Spectrum in de Sitter Inflation, Revisited | 4 pages | Phys.Rev.Lett.101:171301,2008 | 10.1103/PhysRevLett.101.171301 | null | gr-qc astro-ph hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find that the amplitude of quantum fluctuations of the invariant de Sitter
vacuum coincides exactly with that of the vacuum of a comoving observer for a
massless scalar (inflaton) field. We propose redefining the actual physical
power spectrum as the difference between the amplitudes of the above vacua. An
inertial particle detector continues to observe the Gibbons-Hawking
temperature. However, although the resulting power spectrum is still
scale-free, its amplitude can be drastically reduced since now, instead of the
Hubble's scale at the inflationary period, it is determined by the square of
the mass of the inflaton fluctuation field.
| [
{
"created": "Fri, 30 May 2008 21:57:40 GMT",
"version": "v1"
}
] | 2010-05-12 | [
[
"Agullo",
"Ivan",
""
],
[
"Navarro-Salas",
"Jose",
""
],
[
"Olmo",
"Gonzalo J.",
""
],
[
"Parker",
"Leonard",
""
]
] | We find that the amplitude of quantum fluctuations of the invariant de Sitter vacuum coincides exactly with that of the vacuum of a comoving observer for a massless scalar (inflaton) field. We propose redefining the actual physical power spectrum as the difference between the amplitudes of the above vacua. An inertial particle detector continues to observe the Gibbons-Hawking temperature. However, although the resulting power spectrum is still scale-free, its amplitude can be drastically reduced since now, instead of the Hubble's scale at the inflationary period, it is determined by the square of the mass of the inflaton fluctuation field. |
gr-qc/0412087 | Peter Langfelder | Peter Langfelder and Robert B. Mann | A note on spherically symmetric naked singularities in general dimension | 16 pages, no figures, typos fixed | Class.Quant.Grav. 22 (2005) 1917-1932 | 10.1088/0264-9381/22/11/002 | null | gr-qc hep-th | null | We discuss generalizations of the recent theorem by Dafermos (hep-th/0403033)
forbidding a certain class of naked singularities in the spherical collapse of
a scalar field. Employing techniques similar to the ones Dafermos used, we
consider extending the theorem (1) to higher dimensions, (2) by including more
general matter represented by a stress-energy tensor satisfying certain
assumptions, and (3) by replacing the spherical geometry by a toroidal or
higher genus (locally hyperbolic) one. We show that the extension to higher
dimensions and a more general topology is straightforward; on the other hand,
replacing the scalar field by a more general matter content forces us to shrink
the class of naked singularities we are able to exclude. We then show that the
most common matter theories (scalar field interacting with a non-abelian gauge
field and a perfect fluid satisfying certain conditions) obey the assumptions
of our weaker theorem, and we end by commenting on the applicability of our
results to the five-dimensional AdS scenarii considered recently in the
literature.
| [
{
"created": "Fri, 17 Dec 2004 20:27:20 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Mar 2005 17:35:36 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Langfelder",
"Peter",
""
],
[
"Mann",
"Robert B.",
""
]
] | We discuss generalizations of the recent theorem by Dafermos (hep-th/0403033) forbidding a certain class of naked singularities in the spherical collapse of a scalar field. Employing techniques similar to the ones Dafermos used, we consider extending the theorem (1) to higher dimensions, (2) by including more general matter represented by a stress-energy tensor satisfying certain assumptions, and (3) by replacing the spherical geometry by a toroidal or higher genus (locally hyperbolic) one. We show that the extension to higher dimensions and a more general topology is straightforward; on the other hand, replacing the scalar field by a more general matter content forces us to shrink the class of naked singularities we are able to exclude. We then show that the most common matter theories (scalar field interacting with a non-abelian gauge field and a perfect fluid satisfying certain conditions) obey the assumptions of our weaker theorem, and we end by commenting on the applicability of our results to the five-dimensional AdS scenarii considered recently in the literature. |
0907.0826 | Andrew DeBenedictis | A. DeBenedictis | On the black hole singularity issue in loop quantum gravity | 8 pages, 3 figures. Slightly expanded version of a presentation for
an invited talk at Theory Canada IV (2008), Montreal. References and
developments reported on (fairly) current as of the date of the conference
(June 2008) | Can.J.Phys.87:255-262,2009 | 10.1139/P08-077 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper presents a brief overview on the issue of singularity resolution
in loop quantum gravity presented at the Theory Canada IV conference at the
Centre de Recherches Math\'{e}matiques at the Universit\'{e} de Montr\'{e}al
(June 4-7, 2008). The intended audience is theoretical physicists who are
non-specialist in the field and therefore much of the technical detail is
omitted here. Instead, a brief review of loop quantum gravity is presented,
followed by a survey of previous and current work on results concerning the
resolution of the classical black hole singularity within loop quantum gravity.
| [
{
"created": "Sun, 5 Jul 2009 06:17:20 GMT",
"version": "v1"
}
] | 2009-07-17 | [
[
"DeBenedictis",
"A.",
""
]
] | This paper presents a brief overview on the issue of singularity resolution in loop quantum gravity presented at the Theory Canada IV conference at the Centre de Recherches Math\'{e}matiques at the Universit\'{e} de Montr\'{e}al (June 4-7, 2008). The intended audience is theoretical physicists who are non-specialist in the field and therefore much of the technical detail is omitted here. Instead, a brief review of loop quantum gravity is presented, followed by a survey of previous and current work on results concerning the resolution of the classical black hole singularity within loop quantum gravity. |
gr-qc/9312010 | Sergey Tertychniy | S.Tertychniy | On the principles of description of time and space relationships in
frames of general relativity | 22 pages, uuencoded compressed PostScript, no local number | null | null | null | gr-qc | null | The problem of the referring of space and time relationships between physical
objects in a curved space-time is discussed. The basic notions of column and
weak column that could constitute the basis for consistent general relativistic
description of measurements of space and time relations are introduced and the
corresponding equations are derived. A column of observers is proposed to
realize still vague notion of `non-inertial frame of reference' in case of
curved space-time, the criterion distinguishing `inertial columns' is suggested
as well. A number of solutions of column equations is described. They are
applied for calculation of gravitational, inertial (or gravitational-inertial
in more general situation) and ``external" forces and the strength of
gravitational field in several cases of physical interest. In particular, the
`general relativistic' version of Newton's law of inverse squares is derived in
case of the interaction of test particle with a static central symmetric body.
| [
{
"created": "Fri, 3 Dec 1993 19:57:32 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Tertychniy",
"S.",
""
]
] | The problem of the referring of space and time relationships between physical objects in a curved space-time is discussed. The basic notions of column and weak column that could constitute the basis for consistent general relativistic description of measurements of space and time relations are introduced and the corresponding equations are derived. A column of observers is proposed to realize still vague notion of `non-inertial frame of reference' in case of curved space-time, the criterion distinguishing `inertial columns' is suggested as well. A number of solutions of column equations is described. They are applied for calculation of gravitational, inertial (or gravitational-inertial in more general situation) and ``external" forces and the strength of gravitational field in several cases of physical interest. In particular, the `general relativistic' version of Newton's law of inverse squares is derived in case of the interaction of test particle with a static central symmetric body. |
2111.06986 | David Reitze | David Reitze, Michele Punturo, Peter Couvares, Stavros Katsanevas,
Takaaki Kajita, Vicky Kalogera, Harald Lueck, David McClelland, Sheila Rowan,
Gary Sanders, B.S. Sathyaprakash, David Shoemaker, Jo van den Brand | Expanding the Reach of Gravitational Wave Astronomy to the Edge of the
Universe: The Gravitational-Wave International Committee Study Reports on
Next Generation Ground-based Gravitational-Wave Observatories | 7 pages, no figures | null | null | null | gr-qc astro-ph.HE astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | The first direct detection of gravitational waves emitted from a pair of
merging black holes in 2015 has been heralded as one of most significant
scientific breakthroughs in physics and astronomy of the 21st century.
Motivated by the tremendous scientific opportunities now opened by
gravitational-wave observatories and recognizing that to fully exploit the new
field will require new observatories that may take 15 to 20 years from
conception until operations begin, the Gravitational Wave International
Committee (GWIC) convened a subcommittee to examine the path to build and
operate a network of future ground-based observatories, capable of extending
the observational GW horizon well beyond that currently attainable with the
current generation of detectors.
This report is the first in a six part series of reports by the GWIC 3G
Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the
Edge of the Universe (this report), ii) The Next Generation Global
Gravitational Wave Observatory: The Science Book, iii) 3G R&D: R&D for the Next
Generation of Ground-based Gravitational Wave Detectors, iv) Gravitational Wave
Data Analysis: Computing Challenges in the 3G Era, v) Future Ground-based
Gravitational-wave Observatories: Synergies with Other Scientific Communities,
and vi) An Exploration of Possible Governance Models for the Future Global
Gravitational-Wave Observatory Network.
| [
{
"created": "Fri, 12 Nov 2021 23:46:06 GMT",
"version": "v1"
}
] | 2021-11-16 | [
[
"Reitze",
"David",
""
],
[
"Punturo",
"Michele",
""
],
[
"Couvares",
"Peter",
""
],
[
"Katsanevas",
"Stavros",
""
],
[
"Kajita",
"Takaaki",
""
],
[
"Kalogera",
"Vicky",
""
],
[
"Lueck",
"Harald",
""
],
... | The first direct detection of gravitational waves emitted from a pair of merging black holes in 2015 has been heralded as one of most significant scientific breakthroughs in physics and astronomy of the 21st century. Motivated by the tremendous scientific opportunities now opened by gravitational-wave observatories and recognizing that to fully exploit the new field will require new observatories that may take 15 to 20 years from conception until operations begin, the Gravitational Wave International Committee (GWIC) convened a subcommittee to examine the path to build and operate a network of future ground-based observatories, capable of extending the observational GW horizon well beyond that currently attainable with the current generation of detectors. This report is the first in a six part series of reports by the GWIC 3G Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the Edge of the Universe (this report), ii) The Next Generation Global Gravitational Wave Observatory: The Science Book, iii) 3G R&D: R&D for the Next Generation of Ground-based Gravitational Wave Detectors, iv) Gravitational Wave Data Analysis: Computing Challenges in the 3G Era, v) Future Ground-based Gravitational-wave Observatories: Synergies with Other Scientific Communities, and vi) An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network. |
1005.5447 | Sergei Maydanyuk | Sergei P. Maydanyuk | Resonant structure of space-time of early universe | 18 pages, 14 figures, 4 tables | Eur.Phys.J.Plus 126:76,2011 | 10.1140/epjp/i2011-11076-x | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new fully quantum method describing penetration of packet from internal
well outside with its tunneling through the barrier of arbitrary shape used in
problems of quantum cosmology, is presented. The method allows to determine
amplitudes of wave function, penetrability $T_{\rm bar}$ and reflection $R_{\rm
bar}$ relatively the barrier (accuracy of the method: $|T_{\rm bar}+R_{\rm
bar}-1| < 1 \cdot 10^{-15}$), coefficient of penetration (i.e. probability of
the packet to penetrate from the internal well outside with its tunneling),
coefficient of oscillations (describing oscillating behavior of the packet
inside the internal well). Using the method, evolution of universe in the
closed Friedmann--Robertson--Walker model with quantization in presence of
positive cosmological constant, radiation and component of generalize Chaplygin
gas is studied. It is established (for the first time): (1) oscillating
dependence of the penetrability on localization of start of the packet; (2)
presence of resonant values of energy of radiation $E_{\rm rad}$, at which the
coefficient of penetration increases strongly. From analysis of these results
it follows: (1) necessity to introduce initial condition into both
non-stationary, and stationary quantum models; (2) presence of some definite
values for the scale factor $a$, where start of expansion of universe is the
most probable; (3) during expansion of universe in the initial stage its radius
is changed not continuously, but passes consequently through definite discrete
values and tends to continuous spectrum in latter time.
| [
{
"created": "Sat, 29 May 2010 11:28:48 GMT",
"version": "v1"
}
] | 2011-08-17 | [
[
"Maydanyuk",
"Sergei P.",
""
]
] | A new fully quantum method describing penetration of packet from internal well outside with its tunneling through the barrier of arbitrary shape used in problems of quantum cosmology, is presented. The method allows to determine amplitudes of wave function, penetrability $T_{\rm bar}$ and reflection $R_{\rm bar}$ relatively the barrier (accuracy of the method: $|T_{\rm bar}+R_{\rm bar}-1| < 1 \cdot 10^{-15}$), coefficient of penetration (i.e. probability of the packet to penetrate from the internal well outside with its tunneling), coefficient of oscillations (describing oscillating behavior of the packet inside the internal well). Using the method, evolution of universe in the closed Friedmann--Robertson--Walker model with quantization in presence of positive cosmological constant, radiation and component of generalize Chaplygin gas is studied. It is established (for the first time): (1) oscillating dependence of the penetrability on localization of start of the packet; (2) presence of resonant values of energy of radiation $E_{\rm rad}$, at which the coefficient of penetration increases strongly. From analysis of these results it follows: (1) necessity to introduce initial condition into both non-stationary, and stationary quantum models; (2) presence of some definite values for the scale factor $a$, where start of expansion of universe is the most probable; (3) during expansion of universe in the initial stage its radius is changed not continuously, but passes consequently through definite discrete values and tends to continuous spectrum in latter time. |
1810.13313 | Kei Yamada | Yuya Nakamura, Daiki Kikuchi, Kei Yamada, Hideki Asada, Nicolas Yunes | Weakly-Gravitating Objects in dynamical Chern-Simons gravity and
Constraints with Gravity Probe B | 29 pages, 2 figures, submitted to CQG | null | 10.1088/1361-6382/ab04c5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Solar system observations have traditionally allowed for very stringent tests
of Einstein's theory of general relativity. We here revisit the possibility of
using these observations to constrain gravitational parity violation as
encapsulated in dynamical Chern-Simons gravity. Working in the small-coupling
and post-Newtonian approximations, we calculate analytically the scalar field
and the gravitomagnetic sector of the gravitational field in the interior and
the exterior of an isolated, weakly-gravitating object with uniform rotation
and a quadrupolar mass deformation. We find that the asymptotic peeling-off
behavior of the exterior fields is consistent with that found for black holes
and neutron stars, as well as for non-relativistic objects, with overall
coefficients that are different and dependent on the structure of the
weak-field source. We then use these fields to explicitly calculate the
dynamical Chern-Simons correction to the spin precession of gyroscopes in orbit
around Earth, which we find to be in the same direction as the Lense-Thirring
effect of General Relativity. We then compare this correction to the spin
precession prediction of General Relativity to the results of the Gravity Probe
B experiment to place a constraint on dynamical Chern-Simons theory that is
consistent with previous approximate estimates. Although we focus primarily on
a single body, our methods can be straightforwardly extended to binary systems
or N-bodies.
| [
{
"created": "Wed, 31 Oct 2018 14:45:45 GMT",
"version": "v1"
}
] | 2019-05-22 | [
[
"Nakamura",
"Yuya",
""
],
[
"Kikuchi",
"Daiki",
""
],
[
"Yamada",
"Kei",
""
],
[
"Asada",
"Hideki",
""
],
[
"Yunes",
"Nicolas",
""
]
] | Solar system observations have traditionally allowed for very stringent tests of Einstein's theory of general relativity. We here revisit the possibility of using these observations to constrain gravitational parity violation as encapsulated in dynamical Chern-Simons gravity. Working in the small-coupling and post-Newtonian approximations, we calculate analytically the scalar field and the gravitomagnetic sector of the gravitational field in the interior and the exterior of an isolated, weakly-gravitating object with uniform rotation and a quadrupolar mass deformation. We find that the asymptotic peeling-off behavior of the exterior fields is consistent with that found for black holes and neutron stars, as well as for non-relativistic objects, with overall coefficients that are different and dependent on the structure of the weak-field source. We then use these fields to explicitly calculate the dynamical Chern-Simons correction to the spin precession of gyroscopes in orbit around Earth, which we find to be in the same direction as the Lense-Thirring effect of General Relativity. We then compare this correction to the spin precession prediction of General Relativity to the results of the Gravity Probe B experiment to place a constraint on dynamical Chern-Simons theory that is consistent with previous approximate estimates. Although we focus primarily on a single body, our methods can be straightforwardly extended to binary systems or N-bodies. |
1706.06735 | Jordan Keller | Jordan Keller | Decay of Solutions to the Maxwell Equations on Schwarzschild-de Sitter
Spacetimes | 26 pages; v2: updated references | null | null | null | gr-qc math-ph math.AP math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we consider solutions of the Maxwell equations on the
Schwarzschild-de Sitter family of black hole spacetimes. We prove that, in the
static region bounded by black hole and cosmological horizons, solutions of the
Maxwell equations decay to stationary Coulomb solutions at a super-polynomial
rate, with decay measured according to ingoing and outgoing null coordinates.
Our method employs a differential transformation of Maxwell tensor components
to obtain higher-order quantities satisfying a Fackerell-Ipser equation, in the
style of Chandrasekhar and the more recent work of Pasqualotto. The analysis of
the Fackerell-Ipser equation is accomplished by means of the vector field
method, with decay estimates for the higher-order quantities leading to decay
estimates for components of the Maxwell tensor.
| [
{
"created": "Wed, 21 Jun 2017 04:23:15 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Jul 2017 16:23:45 GMT",
"version": "v2"
}
] | 2017-07-07 | [
[
"Keller",
"Jordan",
""
]
] | In this work, we consider solutions of the Maxwell equations on the Schwarzschild-de Sitter family of black hole spacetimes. We prove that, in the static region bounded by black hole and cosmological horizons, solutions of the Maxwell equations decay to stationary Coulomb solutions at a super-polynomial rate, with decay measured according to ingoing and outgoing null coordinates. Our method employs a differential transformation of Maxwell tensor components to obtain higher-order quantities satisfying a Fackerell-Ipser equation, in the style of Chandrasekhar and the more recent work of Pasqualotto. The analysis of the Fackerell-Ipser equation is accomplished by means of the vector field method, with decay estimates for the higher-order quantities leading to decay estimates for components of the Maxwell tensor. |
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