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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1812.04031 | Damianos Iosifidis | Damianos Iosifidis | Exactly Solvable Connections in Metric-Affine Gravity | 39 pages, 1 figure, references added | null | 10.1088/1361-6382/ab0be2 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article presents a systematic way to solve for the Affine Connection in
Metric-Affine Geometry. We start by adding to the Einstein-Hilbert action, a
general action that is linear in the connection and its partial derivatives and
respects projective invariance. We then generalize the result for Metric-Affine
f(R) Theories. Finally, we generalize even further and add an action (to the
Einstein-Hilbert) that has an arbitrary dependence on the connection and its
partial derivatives. We wrap up our results as three consecutive Theorems. We
then apply our Theorems to some simple examples in order to illustrate how the
procedure works and also discuss the cases of dynamical/non-dynamical
connections.
| [
{
"created": "Mon, 10 Dec 2018 19:09:20 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Apr 2019 12:48:19 GMT",
"version": "v2"
},
{
"created": "Mon, 24 Jun 2019 07:17:05 GMT",
"version": "v3"
}
] | 2019-06-25 | [
[
"Iosifidis",
"Damianos",
""
]
] | This article presents a systematic way to solve for the Affine Connection in Metric-Affine Geometry. We start by adding to the Einstein-Hilbert action, a general action that is linear in the connection and its partial derivatives and respects projective invariance. We then generalize the result for Metric-Affine f(R) Theories. Finally, we generalize even further and add an action (to the Einstein-Hilbert) that has an arbitrary dependence on the connection and its partial derivatives. We wrap up our results as three consecutive Theorems. We then apply our Theorems to some simple examples in order to illustrate how the procedure works and also discuss the cases of dynamical/non-dynamical connections. |
1710.11177 | John W. Moffat | M. A. Green, J. W. Moffat and V. T. Toth | Modified Gravity (MOG), the speed of gravitational radiation and the
event GW170817/GRB170817A | 6 pages, no figures | null | 10.1016/j.physletb.2018.03.015 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Modified gravity (MOG) is a covariant, relativistic, alternative
gravitational theory whose field equations are derived from an action that
supplements the spacetime metric tensor with vector and scalar fields. Both
gravitational (spin 2) and electromagnetic waves travel on null geodesics of
the theory's one metric. Despite a recent claim to the contrary, MOG satisfies
the weak equivalence principle and is consistent with observations of the
neutron star merger and gamma ray burster event GW170817/GRB170817A.
| [
{
"created": "Mon, 30 Oct 2017 18:38:11 GMT",
"version": "v1"
}
] | 2018-03-14 | [
[
"Green",
"M. A.",
""
],
[
"Moffat",
"J. W.",
""
],
[
"Toth",
"V. T.",
""
]
] | Modified gravity (MOG) is a covariant, relativistic, alternative gravitational theory whose field equations are derived from an action that supplements the spacetime metric tensor with vector and scalar fields. Both gravitational (spin 2) and electromagnetic waves travel on null geodesics of the theory's one metric. Despite a recent claim to the contrary, MOG satisfies the weak equivalence principle and is consistent with observations of the neutron star merger and gamma ray burster event GW170817/GRB170817A. |
gr-qc/0209055 | Nicholas G. Phillips | Nicholas G Phillips and B. L. Hu | Noise Kernel and Stress Energy Bi-Tensor of Quantum Fields in
Conformally-Optical Metrics: Schwarzschild Black Holes | 19 pages, RevTeX 4 | null | null | null | gr-qc | null | In Paper II [N. G. Phillips and B. L. Hu, previous abstract] we presented the
details for the regularization of the noise kernel of a quantum scalar field in
optical spacetimes by the modified point separation scheme, and a Gaussian
approximation for the Green function. We worked out the regularized noise
kernel for two examples: hot flat space and optical Schwarzschild metric. In
this paper we consider noise kernels for a scalar field in the Schwarzschild
black hole. Much of the work in the point separation approach is to determine
how the divergent piece conformally transforms. For the Schwarzschild metric we
find that the fluctuations of the stress tensor of the Hawking flux in the far
field region checks with the analytic results given by Campos and Hu earlier
[A. Campos and B. L. Hu, Phys. Rev. D {\bf 58} (1998) 125021; Int. J. Theor.
Phys. {\bf 38} (1999) 1253]. We also verify Page's result [D. N. Page, Phys.
Rev. {\bf D25}, 1499 (1982)] for the stress tensor, which, though used often,
still lacks a rigorous proof, as in his original work the direct use of the
conformal transformation was circumvented. However, as in the optical case, we
show that the Gaussian approximation applied to the Green function produces
significant error in the noise kernel on the Schwarzschild horizon. As before
we identify the failure as occurring at the fourth covariant derivative order.
| [
{
"created": "Tue, 17 Sep 2002 18:10:50 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Phillips",
"Nicholas G",
""
],
[
"Hu",
"B. L.",
""
]
] | In Paper II [N. G. Phillips and B. L. Hu, previous abstract] we presented the details for the regularization of the noise kernel of a quantum scalar field in optical spacetimes by the modified point separation scheme, and a Gaussian approximation for the Green function. We worked out the regularized noise kernel for two examples: hot flat space and optical Schwarzschild metric. In this paper we consider noise kernels for a scalar field in the Schwarzschild black hole. Much of the work in the point separation approach is to determine how the divergent piece conformally transforms. For the Schwarzschild metric we find that the fluctuations of the stress tensor of the Hawking flux in the far field region checks with the analytic results given by Campos and Hu earlier [A. Campos and B. L. Hu, Phys. Rev. D {\bf 58} (1998) 125021; Int. J. Theor. Phys. {\bf 38} (1999) 1253]. We also verify Page's result [D. N. Page, Phys. Rev. {\bf D25}, 1499 (1982)] for the stress tensor, which, though used often, still lacks a rigorous proof, as in his original work the direct use of the conformal transformation was circumvented. However, as in the optical case, we show that the Gaussian approximation applied to the Green function produces significant error in the noise kernel on the Schwarzschild horizon. As before we identify the failure as occurring at the fourth covariant derivative order. |
2211.14747 | Wenting Zhou | Wenting Zhou, Shijing Cheng, and Hongwei Yu | Understanding thermal nature of de Sitter spacetime via inter-detector
interaction | 14 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The seminar discovery by Gibbons and Hawking that a freely falling detector
observes an isotropic background of thermal radiation reveals that de Sitter
space is equivalent to a thermal bath at the Gibbons-Hawking temperature in
Minkowski space, as far as the response rate of the detector is concerned.
Meanwhile, for a static detector which is endowed with a proper acceleration
with respect to the local freely-falling detectors, the temperature becomes the
square root of the sum of the squared Gibbons-Hawking temperature and the
squared Unruh temperature associated with the proper acceleration of the
detector. Here, we demonstrate, by examining the interaction of two static
detectors in the de Sitter invariant vacuum, that de Sitter space in regard to
its thermal nature is unique on its own right in the sense that it is even
neither equivalent to the thermal bath in Minkowski space when the static
detectors become freely-falling nor to the Unruh thermal bath at the
cosmological horizon where the Unruh effect dominates, insofar as the behavior
of the inter-detector interaction in de Sitter space dramatically differs both
from that in the Minkowski thermal bath and the Unruh thermal bath.
| [
{
"created": "Sun, 27 Nov 2022 07:01:48 GMT",
"version": "v1"
}
] | 2022-11-29 | [
[
"Zhou",
"Wenting",
""
],
[
"Cheng",
"Shijing",
""
],
[
"Yu",
"Hongwei",
""
]
] | The seminar discovery by Gibbons and Hawking that a freely falling detector observes an isotropic background of thermal radiation reveals that de Sitter space is equivalent to a thermal bath at the Gibbons-Hawking temperature in Minkowski space, as far as the response rate of the detector is concerned. Meanwhile, for a static detector which is endowed with a proper acceleration with respect to the local freely-falling detectors, the temperature becomes the square root of the sum of the squared Gibbons-Hawking temperature and the squared Unruh temperature associated with the proper acceleration of the detector. Here, we demonstrate, by examining the interaction of two static detectors in the de Sitter invariant vacuum, that de Sitter space in regard to its thermal nature is unique on its own right in the sense that it is even neither equivalent to the thermal bath in Minkowski space when the static detectors become freely-falling nor to the Unruh thermal bath at the cosmological horizon where the Unruh effect dominates, insofar as the behavior of the inter-detector interaction in de Sitter space dramatically differs both from that in the Minkowski thermal bath and the Unruh thermal bath. |
1307.4854 | Lorenzo Sebastiani | R. Myrzakulov, L. Sebastiani and S. Zerbini | Inhomogeneous viscous fluids in FRW universe | 11 pages, references added; Galaxies 2013, 1 | Galaxies, v.1, N2, 83-95 (2013) | 10.3390/galaxies1020083 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a brief review of some aspects of inhomogeneous viscous fluids in a
flat Friedmann-Robertson-Walker Universe. In general, it is pointed out that
several fluid models may bring the future Universe evolution to become
singular, with the appearance of the so-called Big Rip scenario. We investigate
the effects of fluids coupled with dark matter in a de Sitter Universe, by
considering several cases. Due to this coupling, the coincidence problem may be
solved, and if the de Sitter solution is stable, the model is also protected
against the Big Rip singularity.
| [
{
"created": "Thu, 18 Jul 2013 07:51:34 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Jul 2013 08:17:37 GMT",
"version": "v2"
}
] | 2013-11-19 | [
[
"Myrzakulov",
"R.",
""
],
[
"Sebastiani",
"L.",
""
],
[
"Zerbini",
"S.",
""
]
] | We give a brief review of some aspects of inhomogeneous viscous fluids in a flat Friedmann-Robertson-Walker Universe. In general, it is pointed out that several fluid models may bring the future Universe evolution to become singular, with the appearance of the so-called Big Rip scenario. We investigate the effects of fluids coupled with dark matter in a de Sitter Universe, by considering several cases. Due to this coupling, the coincidence problem may be solved, and if the de Sitter solution is stable, the model is also protected against the Big Rip singularity. |
2402.00813 | Panagiota Kolitsidou | Panagiota Kolitsidou, Jonathan E. Thompson, Mark Hannam | Impact of anti-symmetric contributions to signal multipoles in the
measurement of black-hole spins | 14 pages, 8 figures | null | null | LIGO-P2300431 | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Many current models for the gravitational-wave signal from precessing
black-hole binaries neglect an asymmetry in the $\pm m$ multipoles. The
asymmetry is weak, but is responsible for out-of-plane recoil, which for the
final black hole can be several thousand km/s. In this work we show that the
multipole asymmetry is also necessary to accurately measure the black-hole
spins. We consider synthetic signals calculated from the numerical relativity
surrogate model NRSur7dq4, which includes the multipole asymmetry, and measure
the signal parameters using two versions of the same model, one with and one
without the multipole asymmetry included. We find that in high
signal-to-noise-ratio observations where the spin magnitude and direction can
in principle be measured accurately, neglecting the multipole asymmetry can
result in biased measurements of these quantities. Measurements of the
black-hole masses and the standard aligned-spin combination $\chi_{\rm eff}$
are not in general strongly affected. As an illustration of the impact of the
multipole asymmetry on a real signal we consider the LVK observation
GW200129_065458, and find that the inclusion of the multipole asymmetry is
necessary to identify the binary as unequal-mass and a high in-plane spin in
the primary.
| [
{
"created": "Thu, 1 Feb 2024 17:51:38 GMT",
"version": "v1"
}
] | 2024-02-02 | [
[
"Kolitsidou",
"Panagiota",
""
],
[
"Thompson",
"Jonathan E.",
""
],
[
"Hannam",
"Mark",
""
]
] | Many current models for the gravitational-wave signal from precessing black-hole binaries neglect an asymmetry in the $\pm m$ multipoles. The asymmetry is weak, but is responsible for out-of-plane recoil, which for the final black hole can be several thousand km/s. In this work we show that the multipole asymmetry is also necessary to accurately measure the black-hole spins. We consider synthetic signals calculated from the numerical relativity surrogate model NRSur7dq4, which includes the multipole asymmetry, and measure the signal parameters using two versions of the same model, one with and one without the multipole asymmetry included. We find that in high signal-to-noise-ratio observations where the spin magnitude and direction can in principle be measured accurately, neglecting the multipole asymmetry can result in biased measurements of these quantities. Measurements of the black-hole masses and the standard aligned-spin combination $\chi_{\rm eff}$ are not in general strongly affected. As an illustration of the impact of the multipole asymmetry on a real signal we consider the LVK observation GW200129_065458, and find that the inclusion of the multipole asymmetry is necessary to identify the binary as unequal-mass and a high in-plane spin in the primary. |
gr-qc/0310010 | Xin-Zhou Li | Xiang-hua Zhai, Li-ping Fu | Features of Motion Around Charged D-Stars | 9 pages, 2 figures | Nuovo Cim.B119:157-166,2004 | 10.1393/ncb/i2003-10091-6 | null | gr-qc | null | The motion of light and a neutral test particle around the charged D-star has
been studied. The difference of the deficit angle of light from the case in
asymptotically flat spacetime is in a factor $(1-\epsilon^2)$. The motion of a
test particle is affected by the deficit angle and the charge. Through the
phase analysis, we prove the existence of the periodic solution to the equation
of motion and the effect of the deficit angle and the charge to the critical
point and its type. We also give the conditions under which the critical point
is a stable center and an unstable saddle point.
| [
{
"created": "Thu, 2 Oct 2003 07:23:04 GMT",
"version": "v1"
}
] | 2011-08-24 | [
[
"Zhai",
"Xiang-hua",
""
],
[
"Fu",
"Li-ping",
""
]
] | The motion of light and a neutral test particle around the charged D-star has been studied. The difference of the deficit angle of light from the case in asymptotically flat spacetime is in a factor $(1-\epsilon^2)$. The motion of a test particle is affected by the deficit angle and the charge. Through the phase analysis, we prove the existence of the periodic solution to the equation of motion and the effect of the deficit angle and the charge to the critical point and its type. We also give the conditions under which the critical point is a stable center and an unstable saddle point. |
1704.02931 | Vasilis Oikonomou | S.D. Odintsov, V.K. Oikonomou | Inflation with a Smooth Constant-Roll to Constant-Roll Era Transition | PRD accepted | Phys. Rev. D 96, 024029 (2017) | 10.1103/PhysRevD.96.024029 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we study canonical scalar field models with a varying second
slow-roll parameter, that allow transitions between constant-roll eras. In the
models with two constant-roll eras it is possible to avoid fine-tunings in the
initial conditions of the scalar field. We mainly focus on the stability of the
resulting solutions and we also investigate if these solutions are attractors
of the cosmological system. We shall calculate the resulting scalar potential
and by using a numerical approach, we examine the stability and attractor
properties of the solutions. As we show, the first constant-roll era is
dynamically unstable towards linear perturbations and the cosmological system
is driven by the attractor solution to the final constant-roll era. As we
demonstrate, it is possible to have a nearly-scale invariant power spectrum of
primordial curvature perturbations in some cases, however this is strongly
model dependent and depends on the rate of the final constant-roll era.
Finally, we present in brief the essential features of a model that allows
oscillations between constant-roll eras.
| [
{
"created": "Mon, 10 Apr 2017 16:16:06 GMT",
"version": "v1"
},
{
"created": "Sun, 25 Jun 2017 18:21:18 GMT",
"version": "v2"
}
] | 2017-07-26 | [
[
"Odintsov",
"S. D.",
""
],
[
"Oikonomou",
"V. K.",
""
]
] | In this paper we study canonical scalar field models with a varying second slow-roll parameter, that allow transitions between constant-roll eras. In the models with two constant-roll eras it is possible to avoid fine-tunings in the initial conditions of the scalar field. We mainly focus on the stability of the resulting solutions and we also investigate if these solutions are attractors of the cosmological system. We shall calculate the resulting scalar potential and by using a numerical approach, we examine the stability and attractor properties of the solutions. As we show, the first constant-roll era is dynamically unstable towards linear perturbations and the cosmological system is driven by the attractor solution to the final constant-roll era. As we demonstrate, it is possible to have a nearly-scale invariant power spectrum of primordial curvature perturbations in some cases, however this is strongly model dependent and depends on the rate of the final constant-roll era. Finally, we present in brief the essential features of a model that allows oscillations between constant-roll eras. |
gr-qc/0506127 | Ettore Minguzzi | E. Minguzzi | Simultaneity in special and general relativity | Latex2e, 9 pages, no figures. To appear in the proceedings of the
school 'Relativistic Coordinates, Reference and Positioning Systems',
Salamanca (Spain), January 21-25, 2005 | null | null | null | gr-qc | null | We present some basic facts concerning simultaneity in both special and
general relativity. We discuss Weyl's proof of the consistence of Einstein's
synchronization convention and consider the general relativistic problem of
assigning a time function to a congruence of timelike curves.
| [
{
"created": "Tue, 28 Jun 2005 10:24:42 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Minguzzi",
"E.",
""
]
] | We present some basic facts concerning simultaneity in both special and general relativity. We discuss Weyl's proof of the consistence of Einstein's synchronization convention and consider the general relativistic problem of assigning a time function to a congruence of timelike curves. |
1104.5471 | James Ryan | James P. Ryan | Tensor models and embedded Riemann surfaces | 9 pages, 7 fig | null | 10.1103/PhysRevD.85.024010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Tensor models and, more generally, group field theories are candidates for
higher-dimensional quantum gravity, just as matrix models are in the 2d
setting. With the recent advent of a 1/N-expansion for coloured tensor models,
more focus has been given to the study of the topological aspects of their
Feynman graphs. Crucial to the aforementioned analysis were certain subgraphs
known as bubbles and jackets. We demonstrate in the 3d case that these graphs
are generated by matrix models embedded inside the tensor theory. Moreover, we
show that the jacket graphs represent (Heegaard) splitting surfaces for the
triangulation dual to the Feynman graph. With this in hand, we are able to
re-express the Boulatov model as a quantum field theory on these Riemann
surfaces.
| [
{
"created": "Thu, 28 Apr 2011 19:02:57 GMT",
"version": "v1"
}
] | 2013-05-30 | [
[
"Ryan",
"James P.",
""
]
] | Tensor models and, more generally, group field theories are candidates for higher-dimensional quantum gravity, just as matrix models are in the 2d setting. With the recent advent of a 1/N-expansion for coloured tensor models, more focus has been given to the study of the topological aspects of their Feynman graphs. Crucial to the aforementioned analysis were certain subgraphs known as bubbles and jackets. We demonstrate in the 3d case that these graphs are generated by matrix models embedded inside the tensor theory. Moreover, we show that the jacket graphs represent (Heegaard) splitting surfaces for the triangulation dual to the Feynman graph. With this in hand, we are able to re-express the Boulatov model as a quantum field theory on these Riemann surfaces. |
1506.07122 | Morgan Le Delliou | Alan Maciel, Morgan Le Delliou (IFT-UNESP), Jos\'e P. Mimoso (DFUL) | A dual null formalism for the collapse of fluids in a cosmological
background | 10pp 1 fig. corrected for equation labels, cross listing corrected | Phys. Rev. D 92, 083525 (2015) | 10.1103/PhysRevD.92.083525 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we revisit the definition of Matter Trapping Surfaces (MTS)
introduced in previous investigations and show how it can be expressed in the
so-called dual null formalism developed for Trapping Horizons (TH). With the
aim of unifying both approaches, we construct a 2+2 threading from the 1+3
flow, and thus isolate one prefered spatial direction, that allows
straightforward translation into a dual nul subbasis, and to deduce the
geometric apparatus that follows. We remain as general as possible, reverting
to spherical symmetry only when needed, and express the MTS conditions in terms
of 2-expansion of the flow, then in purely geometric form of the dual null
expansions. The Raychadhuri equations that describe both MTS and TH are written
and interpreted using the previously defined gTOV (generalized
Tolman-Oppenheimer-Volkov) functional introduced in previous work. Further
using the Misner-Sharp mass and its previous perfect fluid definition, we
relate the spatial 2-expansion to the fluid pressure, density and acceleration.
The Raychaudhuri equations also allows us to define the MTS dynamic condition
with first order differentials so the MTS conditions are now shown to be all
first order differentials. This unified formalism allows one to realise that
the MTS can only exist in normal regions, and so it can exist only between
black hole horizons and cosmological horizons. Finally we obtain a relation
yielding the sign, on a TH, of the non-vanishing null expansion which
determines the nature of the TH from fluid content, and flow characteristics.
The 2+2 unified formalism here investigated thus proves a powerful tool to
reveal, in the future extensions, more of the very rich and subtle relations
between MTS and TH.
| [
{
"created": "Tue, 23 Jun 2015 18:27:00 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Jun 2015 18:20:51 GMT",
"version": "v2"
}
] | 2015-10-28 | [
[
"Maciel",
"Alan",
"",
"IFT-UNESP"
],
[
"Delliou",
"Morgan Le",
"",
"IFT-UNESP"
],
[
"Mimoso",
"José P.",
"",
"DFUL"
]
] | In this work we revisit the definition of Matter Trapping Surfaces (MTS) introduced in previous investigations and show how it can be expressed in the so-called dual null formalism developed for Trapping Horizons (TH). With the aim of unifying both approaches, we construct a 2+2 threading from the 1+3 flow, and thus isolate one prefered spatial direction, that allows straightforward translation into a dual nul subbasis, and to deduce the geometric apparatus that follows. We remain as general as possible, reverting to spherical symmetry only when needed, and express the MTS conditions in terms of 2-expansion of the flow, then in purely geometric form of the dual null expansions. The Raychadhuri equations that describe both MTS and TH are written and interpreted using the previously defined gTOV (generalized Tolman-Oppenheimer-Volkov) functional introduced in previous work. Further using the Misner-Sharp mass and its previous perfect fluid definition, we relate the spatial 2-expansion to the fluid pressure, density and acceleration. The Raychaudhuri equations also allows us to define the MTS dynamic condition with first order differentials so the MTS conditions are now shown to be all first order differentials. This unified formalism allows one to realise that the MTS can only exist in normal regions, and so it can exist only between black hole horizons and cosmological horizons. Finally we obtain a relation yielding the sign, on a TH, of the non-vanishing null expansion which determines the nature of the TH from fluid content, and flow characteristics. The 2+2 unified formalism here investigated thus proves a powerful tool to reveal, in the future extensions, more of the very rich and subtle relations between MTS and TH. |
2406.03279 | Lorenzo Boldorini | L. Boldorini and G. Montani | Effective Quantum Gravitational Collapse in a Polymer Framework | 18 pages, 13 figures, submitted to PRD. Added references | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We study how the presence of an area gap, different than zero, affects the
gravitational collapse of a dust ball. The implementation of such discreteness
is achieved through the framework of polymer quantization, a scheme inspired by
loop quantum gravity (LQG). We study the collapse using variables which
represent the area, in order to impose the non-zero area gap condition. The
collapse is analyzed for both the flat and spherical Oppenheimer-Snyder models.
In both scenarios the formation of the singularity is avoided, due to the
inversion of the velocity at finite values of the sphere surface. This happens
due to the presence of a negative pressure, with origins at a quantum level.
When the inversion happens inside the black hole event horizon, we achieve a
geometry transition to a white hole. When the inversion happens outside the
event horizon, we find a new possible astrophysical object. A characterization
of such hypothetical object is done. Some constraints on the value for the area
gap are also imposed in order to maintain the link with our already established
physical theories.
| [
{
"created": "Wed, 5 Jun 2024 13:54:22 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Jun 2024 13:24:19 GMT",
"version": "v2"
}
] | 2024-06-14 | [
[
"Boldorini",
"L.",
""
],
[
"Montani",
"G.",
""
]
] | We study how the presence of an area gap, different than zero, affects the gravitational collapse of a dust ball. The implementation of such discreteness is achieved through the framework of polymer quantization, a scheme inspired by loop quantum gravity (LQG). We study the collapse using variables which represent the area, in order to impose the non-zero area gap condition. The collapse is analyzed for both the flat and spherical Oppenheimer-Snyder models. In both scenarios the formation of the singularity is avoided, due to the inversion of the velocity at finite values of the sphere surface. This happens due to the presence of a negative pressure, with origins at a quantum level. When the inversion happens inside the black hole event horizon, we achieve a geometry transition to a white hole. When the inversion happens outside the event horizon, we find a new possible astrophysical object. A characterization of such hypothetical object is done. Some constraints on the value for the area gap are also imposed in order to maintain the link with our already established physical theories. |
1209.3791 | Eugen Simanek | Eugen Simanek | Energy quantization for matter orbiting black hole and Hawking radiation | null | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The energy of a test particle orbiting a Schwarzschild black hole is
quantized owing to the quantization of the angular momentum. For smallest
stable circular orbit, the excitation energy is found to resemble closely the
expression for the temperature of the Hawking radiation. This result is
consistent with the Unruh effect for orbiting test particle. The predicted
energy quantization might be observable by studies of the red-shifted 21-cm
line of neutral hydrogen orbiting a primordial black hole with mass of the
order of that of Earth.
| [
{
"created": "Fri, 31 Aug 2012 20:12:13 GMT",
"version": "v1"
}
] | 2012-09-19 | [
[
"Simanek",
"Eugen",
""
]
] | The energy of a test particle orbiting a Schwarzschild black hole is quantized owing to the quantization of the angular momentum. For smallest stable circular orbit, the excitation energy is found to resemble closely the expression for the temperature of the Hawking radiation. This result is consistent with the Unruh effect for orbiting test particle. The predicted energy quantization might be observable by studies of the red-shifted 21-cm line of neutral hydrogen orbiting a primordial black hole with mass of the order of that of Earth. |
gr-qc/0408076 | Massimo Tinto | Massimo Tinto, and Malik Rakhmanov | On the laser frequency stabilization by locking to a LISA arm | 3 pages, 1 figure | null | null | null | gr-qc | null | LISA is an array of three spacecraft flying in an approximately equilateral
triangle configuration, which will be used as a low-frequency detector of
gravitational waves. Recently a technique has been proposed for suppressing the
phase noise of the onboard lasers by locking them to the LISA arms. In this
paper we show that the delay-induced effects substantially modify the
performance of this technique, making it different from the conventional
locking of lasers to optical resonators. We analyze these delay-induced effects
in both transient and steady-state regimes and discuss their implications for
the implementation of this technique on LISA.
| [
{
"created": "Sat, 21 Aug 2004 18:46:54 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Tinto",
"Massimo",
""
],
[
"Rakhmanov",
"Malik",
""
]
] | LISA is an array of three spacecraft flying in an approximately equilateral triangle configuration, which will be used as a low-frequency detector of gravitational waves. Recently a technique has been proposed for suppressing the phase noise of the onboard lasers by locking them to the LISA arms. In this paper we show that the delay-induced effects substantially modify the performance of this technique, making it different from the conventional locking of lasers to optical resonators. We analyze these delay-induced effects in both transient and steady-state regimes and discuss their implications for the implementation of this technique on LISA. |
2403.00531 | Esha Bhatia | Esha Bhatia, Sayan Chakrabarti, Sovan Chakraborty | Phenomenology of renormalization group improved gravity from the
kinematics of SPARC galaxies | 17 pages, 23 figures | null | null | null | gr-qc astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Renormalization Group correction to General Relativity (RGGR) proposes a
logarithmic running of the gravitational coupling $\left(G\right)$, resulting
in a modified description of gravity. This has the potential to explain the
observed kinematics of the galaxies, including the missing-mass problem. We,
for the first time, based on the galaxy morphological types, investigate the
dynamics of a diverse collection of galaxies present in the Spitzer Photometry
for Accurate Rotation Curve (SPARC) catalog. We phenomenologically constrain
the RGGR model parameter $\left(\bar\nu\right)$ along with the mass-to-light
ratio for a sample of 100 SPARC galaxies, selected from four different
morphological types, viz. early, spiral, late, and starburst. Our statistical
analysis finds RGGR to fit the observed galaxy kinematics consistently. The
constrained RGGR model parameter also supports the claim that it has a
near-linear dependence on the galactic baryonic mass. From our morphology
study, we find that the parameter $\bar\nu$ decreases from the early-type to
the starburst galaxies. Finally, the renormalization group improved gravity is
tested against the two established empirical relations for the SPARC catalog,
viz., the Radial Acceleration Relation (RAR) and the Baryonic Tully Fisher
relation (BTFR), both are found to be satisfied consistently.
| [
{
"created": "Fri, 1 Mar 2024 13:43:31 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Aug 2024 08:51:19 GMT",
"version": "v2"
}
] | 2024-08-02 | [
[
"Bhatia",
"Esha",
""
],
[
"Chakrabarti",
"Sayan",
""
],
[
"Chakraborty",
"Sovan",
""
]
] | Renormalization Group correction to General Relativity (RGGR) proposes a logarithmic running of the gravitational coupling $\left(G\right)$, resulting in a modified description of gravity. This has the potential to explain the observed kinematics of the galaxies, including the missing-mass problem. We, for the first time, based on the galaxy morphological types, investigate the dynamics of a diverse collection of galaxies present in the Spitzer Photometry for Accurate Rotation Curve (SPARC) catalog. We phenomenologically constrain the RGGR model parameter $\left(\bar\nu\right)$ along with the mass-to-light ratio for a sample of 100 SPARC galaxies, selected from four different morphological types, viz. early, spiral, late, and starburst. Our statistical analysis finds RGGR to fit the observed galaxy kinematics consistently. The constrained RGGR model parameter also supports the claim that it has a near-linear dependence on the galactic baryonic mass. From our morphology study, we find that the parameter $\bar\nu$ decreases from the early-type to the starburst galaxies. Finally, the renormalization group improved gravity is tested against the two established empirical relations for the SPARC catalog, viz., the Radial Acceleration Relation (RAR) and the Baryonic Tully Fisher relation (BTFR), both are found to be satisfied consistently. |
2012.01066 | Peng Wang | Peng Wang, Houwen Wu, Haitang Yang | Scalarized Einstein-Born-Infeld-scalar Black Holes | v1: 27 pages, 7 figures; v2: 27 pages, 7 figures, references added | Phys. Rev. D 103, 104012 (2021) | 10.1103/PhysRevD.103.104012 | CTP-SCU/2020037 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The phenomenon of spontaneous scalarization of Reissner-Nordstr\"{o}m (RN)
black holes has recently been found in an Einstein-Maxwell-scalar (EMS) model
due to a non-minimal coupling between the scalar and Maxwell fields. Non-linear
electrodynamics, e.g., Born-Infeld (BI) electrodynamics, generalizes Maxwell's
theory in the strong field regime. Non-minimally coupling the BI field to the
scalar field, we study spontaneous scalarization of an
Einstein-Born-Infeld-scalar (EBIS) model in this paper. It shows that there are
two types of scalarized black hole solutions, i.e., scalarized RN-like and
Schwarzschild-like solutions. Although the behavior of scalarized RN-like
solutions in the EBIS model is quite similar to that of scalarize solutions in
the EMS model, we find that there exist significant differences between
scalarized Schwarzschild-like solutions in the EBIS model and scalarized
solutions in the EMS model. In particular, the domain of existence of
scalarized Schwarzschild-like solutions possesses a certain region, which is
composed of two branches. The branch of larger horizon area is a family of
disconnected scalarized solutions, which do not bifurcate from scalar-free
black holes. However, the branch of smaller horizon area may or may not
bifurcate from scalar-free black holes depending on the parameters.
Additionally, these two branches of scalarized solutions can be both
entropically disfavored over comparable scalar-free black holes in some
parameter region.
| [
{
"created": "Wed, 2 Dec 2020 10:18:33 GMT",
"version": "v1"
},
{
"created": "Sun, 7 Feb 2021 09:21:18 GMT",
"version": "v2"
}
] | 2021-05-19 | [
[
"Wang",
"Peng",
""
],
[
"Wu",
"Houwen",
""
],
[
"Yang",
"Haitang",
""
]
] | The phenomenon of spontaneous scalarization of Reissner-Nordstr\"{o}m (RN) black holes has recently been found in an Einstein-Maxwell-scalar (EMS) model due to a non-minimal coupling between the scalar and Maxwell fields. Non-linear electrodynamics, e.g., Born-Infeld (BI) electrodynamics, generalizes Maxwell's theory in the strong field regime. Non-minimally coupling the BI field to the scalar field, we study spontaneous scalarization of an Einstein-Born-Infeld-scalar (EBIS) model in this paper. It shows that there are two types of scalarized black hole solutions, i.e., scalarized RN-like and Schwarzschild-like solutions. Although the behavior of scalarized RN-like solutions in the EBIS model is quite similar to that of scalarize solutions in the EMS model, we find that there exist significant differences between scalarized Schwarzschild-like solutions in the EBIS model and scalarized solutions in the EMS model. In particular, the domain of existence of scalarized Schwarzschild-like solutions possesses a certain region, which is composed of two branches. The branch of larger horizon area is a family of disconnected scalarized solutions, which do not bifurcate from scalar-free black holes. However, the branch of smaller horizon area may or may not bifurcate from scalar-free black holes depending on the parameters. Additionally, these two branches of scalarized solutions can be both entropically disfavored over comparable scalar-free black holes in some parameter region. |
gr-qc/0702091 | Hajime Sotani | Hajime Sotani, Shijun Yoshida, and Kostas D. Kokkotas | Gravitational radiation from collapsing magnetized dust | null | Phys.Rev.D75:084015,2007 | 10.1103/PhysRevD.75.084015 | null | gr-qc | null | In this article we study the influence of magnetic fields on the axial
gravitational waves emitted during the collapse of a homogeneous dust sphere.
We found that while the energy emitted depends weakly on the initial matter
perturbations it has strong dependence on the strength and the distribution of
the magnetic field perturbations. The gravitational wave output of such a
collapse can be up to an order of magnitude larger or smaller calling for
detailed numerical 3D studies of collapsing magnetized configurations.
| [
{
"created": "Thu, 15 Feb 2007 15:09:34 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Sotani",
"Hajime",
""
],
[
"Yoshida",
"Shijun",
""
],
[
"Kokkotas",
"Kostas D.",
""
]
] | In this article we study the influence of magnetic fields on the axial gravitational waves emitted during the collapse of a homogeneous dust sphere. We found that while the energy emitted depends weakly on the initial matter perturbations it has strong dependence on the strength and the distribution of the magnetic field perturbations. The gravitational wave output of such a collapse can be up to an order of magnitude larger or smaller calling for detailed numerical 3D studies of collapsing magnetized configurations. |
2402.19010 | Josef Kluson | J. Kluson | Reparametrization invariant action for Gravity with Dynamical
Determinant of Metric | 22 pages | null | null | null | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | We present manifestly reparametrization invariant action for theory of
gravity with dynamical determinant of metric. We show that it is similar to a
reparametrization invariant action for unimodular gravity. We determine
canonical form of the action and study structure of constraints.
| [
{
"created": "Thu, 29 Feb 2024 10:11:05 GMT",
"version": "v1"
}
] | 2024-03-01 | [
[
"Kluson",
"J.",
""
]
] | We present manifestly reparametrization invariant action for theory of gravity with dynamical determinant of metric. We show that it is similar to a reparametrization invariant action for unimodular gravity. We determine canonical form of the action and study structure of constraints. |
1706.03040 | Cenalo Vaz | Souvik Sarkar and Cenalo Vaz | Canonical Chern-Simons Gravity | null | Physical Review D 96, 024056 (2017) | 10.1103/PhysRevD.96.024056 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the canonical description of the axisymmetric vacuum in 2+1
dimensional gravity, treating Einstein's gravity as a Chern Simons gauge theory
on a manifold with the restriction that the dreibein is invertible. Our
treatment is in the spirit of Kucha\v r's description of the Schwarzschild
black hole in 3+1 dimensions, where the mass and angular momentum are expressed
in terms of the canonical variables and a series of canonical transformations
are performed that turn the curvature coordinates and their conjugate momenta
into new canonical variables. In their final form, the constraints are seen to
require that the momenta conjugate to the Killing time and curvature radius
vanish and what remains are the mass, the angular momentum and their conjugate
momenta, which we derive. The Wheeler-DeWitt equation is trivial and describes
time independent systems with wave functions described only by the total mass
and total angular momentum.
| [
{
"created": "Fri, 9 Jun 2017 16:57:16 GMT",
"version": "v1"
}
] | 2017-09-13 | [
[
"Sarkar",
"Souvik",
""
],
[
"Vaz",
"Cenalo",
""
]
] | We study the canonical description of the axisymmetric vacuum in 2+1 dimensional gravity, treating Einstein's gravity as a Chern Simons gauge theory on a manifold with the restriction that the dreibein is invertible. Our treatment is in the spirit of Kucha\v r's description of the Schwarzschild black hole in 3+1 dimensions, where the mass and angular momentum are expressed in terms of the canonical variables and a series of canonical transformations are performed that turn the curvature coordinates and their conjugate momenta into new canonical variables. In their final form, the constraints are seen to require that the momenta conjugate to the Killing time and curvature radius vanish and what remains are the mass, the angular momentum and their conjugate momenta, which we derive. The Wheeler-DeWitt equation is trivial and describes time independent systems with wave functions described only by the total mass and total angular momentum. |
2004.07515 | Matthew Charles Edwards | Matthew C. Edwards, Patricio Maturana-Russel, Renate Meyer, Jonathan
Gair, Natalia Korsakova, Nelson Christensen | Identifying and Addressing Nonstationary LISA Noise | 19 pages, 17 figures | Phys. Rev. D 102, 084062 (2020) | 10.1103/PhysRevD.102.084062 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We anticipate noise from the Laser Interferometer Space Antenna (LISA) will
exhibit nonstationarities throughout the duration of its mission due to factors
such as antenna repointing, cyclostationarities from spacecraft motion, and
glitches as highlighted by LISA Pathfinder. In this paper, we use a surrogate
data approach to test the stationarity of a time series which does not rely on
the Gaussianity assumption. The main goal is to identify noise
nonstationarities in the future LISA mission. This will be necessary for
determining how often the LISA noise power spectral density (PSD) will need to
be updated for parameter estimation routines. We conduct a thorough simulation
study illustrating the power/size of various versions of the hypothesis tests,
and then apply these approaches to differential acceleration measurements from
LISA Pathfinder. We also develop a data analysis strategy for addressing
nonstationarities in the LISA PSD, where we update the noise PSD over time,
while simultaneously conducting parameter estimation, with a focus on planned
data gaps.
| [
{
"created": "Thu, 16 Apr 2020 08:11:24 GMT",
"version": "v1"
},
{
"created": "Fri, 18 Sep 2020 00:20:10 GMT",
"version": "v2"
}
] | 2020-10-29 | [
[
"Edwards",
"Matthew C.",
""
],
[
"Maturana-Russel",
"Patricio",
""
],
[
"Meyer",
"Renate",
""
],
[
"Gair",
"Jonathan",
""
],
[
"Korsakova",
"Natalia",
""
],
[
"Christensen",
"Nelson",
""
]
] | We anticipate noise from the Laser Interferometer Space Antenna (LISA) will exhibit nonstationarities throughout the duration of its mission due to factors such as antenna repointing, cyclostationarities from spacecraft motion, and glitches as highlighted by LISA Pathfinder. In this paper, we use a surrogate data approach to test the stationarity of a time series which does not rely on the Gaussianity assumption. The main goal is to identify noise nonstationarities in the future LISA mission. This will be necessary for determining how often the LISA noise power spectral density (PSD) will need to be updated for parameter estimation routines. We conduct a thorough simulation study illustrating the power/size of various versions of the hypothesis tests, and then apply these approaches to differential acceleration measurements from LISA Pathfinder. We also develop a data analysis strategy for addressing nonstationarities in the LISA PSD, where we update the noise PSD over time, while simultaneously conducting parameter estimation, with a focus on planned data gaps. |
1307.3599 | Douglas A. Singleton | Preston Jones, Gerardo Munoz, Douglas Singleton, Triyanta | Field localization and Nambu Jona-Lasinio mass generation mechanism in
an alternative 5-dimensional brane model | 25 pages, no figures. Version matches published version, minor
corrections | Phys.Rev. D88 (2013) 025048 | 10.1103/PhysRevD.88.025048 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a 5-dimensional brane world model with a single brane which is
distinct from the well known Randall-Sundrum model. We discuss the similarities
and differences between our brane model and the Randall-Sundrum brane model. In
particular we focus on the localization of 5D fields with different spins --
spin 0, spin 1/2, spin 1 -- to the brane, and a self-consistent mass generation
mechanism. We find that the brane model studied here has different (and in some
cases superior) localization properties for fields/particles with different
spins to the brane, as compared to the original 5-dimensional brane models. In
addition this alternative 5D brane model exhibits a self generation mechanism
which recalls the self-consistent approach of Nambu and Jona-Lasinio.
| [
{
"created": "Sat, 13 Jul 2013 01:22:21 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Aug 2013 21:40:00 GMT",
"version": "v2"
}
] | 2013-08-15 | [
[
"Jones",
"Preston",
""
],
[
"Munoz",
"Gerardo",
""
],
[
"Singleton",
"Douglas",
""
],
[
"Triyanta",
"",
""
]
] | We consider a 5-dimensional brane world model with a single brane which is distinct from the well known Randall-Sundrum model. We discuss the similarities and differences between our brane model and the Randall-Sundrum brane model. In particular we focus on the localization of 5D fields with different spins -- spin 0, spin 1/2, spin 1 -- to the brane, and a self-consistent mass generation mechanism. We find that the brane model studied here has different (and in some cases superior) localization properties for fields/particles with different spins to the brane, as compared to the original 5-dimensional brane models. In addition this alternative 5D brane model exhibits a self generation mechanism which recalls the self-consistent approach of Nambu and Jona-Lasinio. |
1510.06776 | Ashfaque Bokhari | Suhail Khan (1), Tahir Hussain (1), Ashfaque H. Bokhari (2) and Gulzar
Ali Khan (1) (1) Department of Mathematics, University of Peshawar, Peshawar
Khyber Pakhtoonkhwa, Pakistan. (2) Department of Mathematics, King Fahd
University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia | Conformal Killing Vectors Of Plane Symmetric Four Dimensional Lorentzian
Manifolds | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate conformal Killing's vectors (CKVs) admitted by
some plane symmetric spacetimes. Ten conformal Killing's equations and their
general forms of CKVs are derived along with their conformal factor. The
existence of conformal Killing's symmetry imposes restrictions on the metric
functions. The conditions imposing restrictions on these metric functions are
obtained as a set of integrability conditions. Considering the cases of
time-like and inheriting CKVs, we obtain spacetimes admitting plane conformal
symmetry. Integrability conditions are solved completely for some known
non-conformally flat and conformally flat classes of plane symmetric
spacetimes. A special vacuum plane symmetric spacetime is obtained, and it is
shown that for such a metric CKVs are just the homothetic vectors (HVs). Among
all the examples considered, there exists only one case with a six dimensional
algebra of special CKVs admitting one proper CKV. In all other examples of
non-conformally flat metrics, no proper CKV is found and CKVs are either HVs or
Killing's vectors (KVs). In each of the three cases of conformally flat
metrics, a fifteen dimensional algebra of CKVs is obtained of which eight are
proper CKVs.
| [
{
"created": "Thu, 22 Oct 2015 22:00:04 GMT",
"version": "v1"
}
] | 2015-10-26 | [
[
"Khan",
"Suhail",
""
],
[
"Hussain",
"Tahir",
""
],
[
"Bokhari",
"Ashfaque H.",
""
],
[
"Khan",
"Gulzar Ali",
""
],
[
"Mathematics",
"Department of",
""
],
[
"Peshawar",
"University of",
""
],
[
"Pakhtoonkhwa",
... | In this paper, we investigate conformal Killing's vectors (CKVs) admitted by some plane symmetric spacetimes. Ten conformal Killing's equations and their general forms of CKVs are derived along with their conformal factor. The existence of conformal Killing's symmetry imposes restrictions on the metric functions. The conditions imposing restrictions on these metric functions are obtained as a set of integrability conditions. Considering the cases of time-like and inheriting CKVs, we obtain spacetimes admitting plane conformal symmetry. Integrability conditions are solved completely for some known non-conformally flat and conformally flat classes of plane symmetric spacetimes. A special vacuum plane symmetric spacetime is obtained, and it is shown that for such a metric CKVs are just the homothetic vectors (HVs). Among all the examples considered, there exists only one case with a six dimensional algebra of special CKVs admitting one proper CKV. In all other examples of non-conformally flat metrics, no proper CKV is found and CKVs are either HVs or Killing's vectors (KVs). In each of the three cases of conformally flat metrics, a fifteen dimensional algebra of CKVs is obtained of which eight are proper CKVs. |
gr-qc/9910053 | Garcia | L.C.Garcia de Andrade and R.O.Ramos (Universidade do Estado do Rio de
Janeiro) | Spin-torsion in Chaotic Inflation | Latex file 10 Kb | null | null | null | gr-qc | null | The role of spin-torsion coupling to gravity is analyzed in the context of a
model of chaotic inflation. The system of equations constructed from the
Einstein-Cartan and inflaton field equations are studied and it is shown that
spin-torsion interactions are effective only at the very first e-folds of
inflation, becoming quickly negligible and, therefore, not affecting the
standard inflationary scenario nor the density perturbations spectrum
predictions.
| [
{
"created": "Thu, 14 Oct 1999 21:52:03 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"de Andrade",
"L. C. Garcia",
"",
"Universidade do Estado do Rio de\n Janeiro"
],
[
"Ramos",
"R. O.",
"",
"Universidade do Estado do Rio de\n Janeiro"
]
] | The role of spin-torsion coupling to gravity is analyzed in the context of a model of chaotic inflation. The system of equations constructed from the Einstein-Cartan and inflaton field equations are studied and it is shown that spin-torsion interactions are effective only at the very first e-folds of inflation, becoming quickly negligible and, therefore, not affecting the standard inflationary scenario nor the density perturbations spectrum predictions. |
1807.10167 | Orlando Luongo | Rocco D'Agostino, Orlando Luongo | Growth of matter perturbations in non-minimal teleparallel dark energy | 14 pages, 12 figures, accepted for publication in Phys. Rev. D | Phys. Rev. D 98, 124013 (2018) | 10.1103/PhysRevD.98.124013 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the growth rate of matter perturbations in the context of
teleparallel dark energy in a flat universe. We investigate the dynamics of
different theoretical scenarios based on specific forms of the scalar field
potential. Allowing for non-minimal coupling between torsion scalar and scalar
field, we perform a phase-space analysis of the autonomous systems of equations
through the study of critical points. We thus analyze the stability of the
critical points, and discuss the cosmological implications searching for
possible attractor solutions at late times. Furthermore, combing the growth
rate data and the Hubble rate measurements, we place observational constraints
on the cosmological parameters of the models through Monte Carlo numerical
method. We find that the scenario with a non-minimal coupling is favoured with
respect to the standard quintessence case. Adopting the best-fit results, we
show that the dark energy equation of state parameter can cross the phantom
divide. Finally, we compare our results with the predictions of the concordance
$\Lambda$CDM paradigm by performing Bayesian model selection.
| [
{
"created": "Thu, 26 Jul 2018 14:27:54 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Nov 2018 14:26:09 GMT",
"version": "v2"
}
] | 2018-12-19 | [
[
"D'Agostino",
"Rocco",
""
],
[
"Luongo",
"Orlando",
""
]
] | We study the growth rate of matter perturbations in the context of teleparallel dark energy in a flat universe. We investigate the dynamics of different theoretical scenarios based on specific forms of the scalar field potential. Allowing for non-minimal coupling between torsion scalar and scalar field, we perform a phase-space analysis of the autonomous systems of equations through the study of critical points. We thus analyze the stability of the critical points, and discuss the cosmological implications searching for possible attractor solutions at late times. Furthermore, combing the growth rate data and the Hubble rate measurements, we place observational constraints on the cosmological parameters of the models through Monte Carlo numerical method. We find that the scenario with a non-minimal coupling is favoured with respect to the standard quintessence case. Adopting the best-fit results, we show that the dark energy equation of state parameter can cross the phantom divide. Finally, we compare our results with the predictions of the concordance $\Lambda$CDM paradigm by performing Bayesian model selection. |
2205.04462 | Pardyumn Kumar Sahoo | Raja Solanki, Simran Arora, P.K. Sahoo, P.H.R.S. Moraes | Bulk viscous fluid in symmetric teleparallel cosmology: theory versus
experiment | Comments are welcome | Universe, 9(1) (2023) 12 | 10.3390/universe9010012 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The standard formulation of General Relativity Theory, in the absence of a
cosmological constant, is unable to explain the responsible mechanism for the
observed late-time cosmic acceleration. On the other hand, by inserting the
cosmological constant in Einstein's field equations it is possible to describe
the cosmic acceleration, but the cosmological constant suffers from an
unprecedented fine-tunning problem. This motivates one to modify Einstein's
space-time geometry of General Relativity. The $f(Q)$ modified theory of
gravity is an alternative theory to General Relativity, where the non-metricity
scalar $Q$ is the responsible candidate for gravitational interactions. In the
present work we consider a Friedmann-Lem\^aitre-Robertson-Walker cosmological
model dominated by bulk viscous cosmic fluid in $f(Q)$ gravity with the
functional form $f(Q)=\alpha Q^n$, where $\alpha$ and $n$ are free parameters
of the model. We constrain our model with the recent Pantheon supernovae data
set of 1048 data points, Hubble data set of 31 data points and baryon acoustic
oscillations data set consisting of six points. For higher values of redshift,
it is clear that the $f(Q)$ cosmology better fits data than standard cosmology.
We present the evolution of our deceleration parameter with redshift and it
properly predicts a transition from decelerated to accelerated phases of the
universe expansion. Also, we present the evolution of density, bulk viscous
pressure and the effective equation of state parameter with redshift. Those
show that bulk viscosity in a cosmic fluid is a valid candidate to acquire the
negative pressure to drive the cosmic expansion efficiently.We also examine the
behavior of different energy conditions to test the viability of our
cosmological $f(Q)$ model. Furthermore, the statefinder diagnostics are also
investigated in order to distinguish among different dark energy models.
| [
{
"created": "Sat, 7 May 2022 06:03:53 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Nov 2022 00:52:48 GMT",
"version": "v2"
}
] | 2022-12-26 | [
[
"Solanki",
"Raja",
""
],
[
"Arora",
"Simran",
""
],
[
"Sahoo",
"P. K.",
""
],
[
"Moraes",
"P. H. R. S.",
""
]
] | The standard formulation of General Relativity Theory, in the absence of a cosmological constant, is unable to explain the responsible mechanism for the observed late-time cosmic acceleration. On the other hand, by inserting the cosmological constant in Einstein's field equations it is possible to describe the cosmic acceleration, but the cosmological constant suffers from an unprecedented fine-tunning problem. This motivates one to modify Einstein's space-time geometry of General Relativity. The $f(Q)$ modified theory of gravity is an alternative theory to General Relativity, where the non-metricity scalar $Q$ is the responsible candidate for gravitational interactions. In the present work we consider a Friedmann-Lem\^aitre-Robertson-Walker cosmological model dominated by bulk viscous cosmic fluid in $f(Q)$ gravity with the functional form $f(Q)=\alpha Q^n$, where $\alpha$ and $n$ are free parameters of the model. We constrain our model with the recent Pantheon supernovae data set of 1048 data points, Hubble data set of 31 data points and baryon acoustic oscillations data set consisting of six points. For higher values of redshift, it is clear that the $f(Q)$ cosmology better fits data than standard cosmology. We present the evolution of our deceleration parameter with redshift and it properly predicts a transition from decelerated to accelerated phases of the universe expansion. Also, we present the evolution of density, bulk viscous pressure and the effective equation of state parameter with redshift. Those show that bulk viscosity in a cosmic fluid is a valid candidate to acquire the negative pressure to drive the cosmic expansion efficiently.We also examine the behavior of different energy conditions to test the viability of our cosmological $f(Q)$ model. Furthermore, the statefinder diagnostics are also investigated in order to distinguish among different dark energy models. |
gr-qc/0504145 | Michele Vallisneri | Michele Vallisneri | Geometric Time Delay Interferometry | 18 pages REVTeX4, 6 EPS figures, revised PRD version. Related
materials can be found at http://www.vallis.org/tdi | Phys.Rev.D72:042003,2005; Erratum-ibid.D76:109903,2007 | 10.1103/PhysRevD.72.042003 10.1103/PhysRevD.76.109903 | null | gr-qc | null | The space-based gravitational-wave observatory LISA, a NASA-ESA mission to be
launched after 2012, will achieve its optimal sensitivity using Time Delay
Interferometry (TDI), a LISA-specific technique needed to cancel the otherwise
overwhelming laser noise in the inter-spacecraft phase measurements. The TDI
observables of the Michelson and Sagnac types have been interpreted physically
as the virtual measurements of a synthesized interferometer. In this paper, I
present Geometric TDI, a new and intuitive approach to extend this
interpretation to all TDI observables. Unlike the standard algebraic formalism,
Geometric TDI provides a combinatorial algorithm to explore exhaustively the
space of second-generation TDI observables (i.e., those that cancel laser noise
in LISA-like interferometers with time-dependent armlengths). Using this
algorithm, I survey the space of second-generation TDI observables of length
(i.e., number of component phase measurements) up to 24, and I identify
alternative, improved forms of the standard second-generation TDI observables.
The alternative forms have improved high-frequency gravitational-wave
sensitivity in realistic noise conditions (because they have fewer nulls in the
gravitational-wave and noise response functions), and are less susceptible to
instrumental gaps and glitches (because their component phase measurements span
shorter time periods).
| [
{
"created": "Fri, 29 Apr 2005 19:08:15 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Jun 2005 19:27:51 GMT",
"version": "v2"
}
] | 2014-11-17 | [
[
"Vallisneri",
"Michele",
""
]
] | The space-based gravitational-wave observatory LISA, a NASA-ESA mission to be launched after 2012, will achieve its optimal sensitivity using Time Delay Interferometry (TDI), a LISA-specific technique needed to cancel the otherwise overwhelming laser noise in the inter-spacecraft phase measurements. The TDI observables of the Michelson and Sagnac types have been interpreted physically as the virtual measurements of a synthesized interferometer. In this paper, I present Geometric TDI, a new and intuitive approach to extend this interpretation to all TDI observables. Unlike the standard algebraic formalism, Geometric TDI provides a combinatorial algorithm to explore exhaustively the space of second-generation TDI observables (i.e., those that cancel laser noise in LISA-like interferometers with time-dependent armlengths). Using this algorithm, I survey the space of second-generation TDI observables of length (i.e., number of component phase measurements) up to 24, and I identify alternative, improved forms of the standard second-generation TDI observables. The alternative forms have improved high-frequency gravitational-wave sensitivity in realistic noise conditions (because they have fewer nulls in the gravitational-wave and noise response functions), and are less susceptible to instrumental gaps and glitches (because their component phase measurements span shorter time periods). |
2407.15289 | Marco Galoppo | Marco Galoppo, Rudeep Gaur and Christopher Harvey-Hawes | Kerr--Newman Memory Effect | 24 pages, 0 figures | null | null | null | gr-qc hep-th math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | We bring the Kerr--Newman spacetime into the Bondi--Sachs gauge by means of
zero angular momentum, null geodesics. We compute the memory effect produced at
the black hole horizon by a transient gravitational shock wave, which from
future null infinity is seen as a Bondi-Metzner-Sachs supertranslation. This
results in a change of the supertransformation charges at infinity between the
spacetime geometries defined by the black hole before, and after, the shockwave
scattering. For an extremal Kerr--Newman black hole, we give the complementary
description of this process in the near-horizon limit, as seen by an observer
hovering over the horizon. In this limit, we compute the supertranformation
charges and compare them to those calculated at null infinity. We analyze the
effect of these transformations on the electromagnetic gauge field and explore
the self-interaction between this and the angular momentum of the black hole.
| [
{
"created": "Sun, 21 Jul 2024 22:56:38 GMT",
"version": "v1"
}
] | 2024-07-23 | [
[
"Galoppo",
"Marco",
""
],
[
"Gaur",
"Rudeep",
""
],
[
"Harvey-Hawes",
"Christopher",
""
]
] | We bring the Kerr--Newman spacetime into the Bondi--Sachs gauge by means of zero angular momentum, null geodesics. We compute the memory effect produced at the black hole horizon by a transient gravitational shock wave, which from future null infinity is seen as a Bondi-Metzner-Sachs supertranslation. This results in a change of the supertransformation charges at infinity between the spacetime geometries defined by the black hole before, and after, the shockwave scattering. For an extremal Kerr--Newman black hole, we give the complementary description of this process in the near-horizon limit, as seen by an observer hovering over the horizon. In this limit, we compute the supertranformation charges and compare them to those calculated at null infinity. We analyze the effect of these transformations on the electromagnetic gauge field and explore the self-interaction between this and the angular momentum of the black hole. |
gr-qc/0311002 | Francisco Lobo | Francisco S.N. Lobo and Paulo Crawford | Linearized stability analysis of thin-shell wormholes with a
cosmological constant | 16 pages, 10 figures, LaTeX2e, IOP style files. Accepted for
publication in Classical and Quantum Gravity | Class.Quant.Grav. 21 (2004) 391-404 | 10.1088/0264-9381/21/2/004 | null | gr-qc | null | Spherically symmetric thin-shell wormholes in the presence of a cosmological
constant are constructed applying the cut-and-paste technique implemented by
Visser. Using the Darmois-Israel formalism the surface stresses, which are
concentrated at the wormhole throat, are determined. This construction allows
one to apply a dynamical analysis to the throat, considering linearized radial
perturbations around static solutions. For a large positive cosmological
constant, i.e., for the Schwarzschild-de Sitter solution, the region of
stability is significantly increased, relatively to the null cosmological
constant case, analyzed by Poisson and Visser. With a negative cosmological
constant, i.e., the Schwarzschild-anti de Sitter solution, the region of
stability is decreased. In particular, considering static solutions with a
generic cosmological constant, the weak and dominant energy conditions are
violated, while for $a_0 \leq 3M$ the null and strong energy conditions are
satisfied. The surface pressure of the static solution is strictly positive for
the Schwarzschild and Schwarzschild-anti de Sitter spacetimes, but takes
negative values, assuming a surface tension in the Schwarzschild-de Sitter
solution, for high values of the cosmological constant and the wormhole throat
radius.
| [
{
"created": "Sat, 1 Nov 2003 11:33:51 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Lobo",
"Francisco S. N.",
""
],
[
"Crawford",
"Paulo",
""
]
] | Spherically symmetric thin-shell wormholes in the presence of a cosmological constant are constructed applying the cut-and-paste technique implemented by Visser. Using the Darmois-Israel formalism the surface stresses, which are concentrated at the wormhole throat, are determined. This construction allows one to apply a dynamical analysis to the throat, considering linearized radial perturbations around static solutions. For a large positive cosmological constant, i.e., for the Schwarzschild-de Sitter solution, the region of stability is significantly increased, relatively to the null cosmological constant case, analyzed by Poisson and Visser. With a negative cosmological constant, i.e., the Schwarzschild-anti de Sitter solution, the region of stability is decreased. In particular, considering static solutions with a generic cosmological constant, the weak and dominant energy conditions are violated, while for $a_0 \leq 3M$ the null and strong energy conditions are satisfied. The surface pressure of the static solution is strictly positive for the Schwarzschild and Schwarzschild-anti de Sitter spacetimes, but takes negative values, assuming a surface tension in the Schwarzschild-de Sitter solution, for high values of the cosmological constant and the wormhole throat radius. |
1607.07714 | Robert Bluhm | R. Bluhm | Background Fields and Gravity | Presented at the Seventh Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 20-24, 2016 | null | null | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational theories with fixed background fields break diffeomorphism
invariance. This breaking can be spontaneous or explicit. A brief summary of
the main consequences of these types of breaking is presented.
| [
{
"created": "Tue, 26 Jul 2016 14:25:05 GMT",
"version": "v1"
}
] | 2016-07-27 | [
[
"Bluhm",
"R.",
""
]
] | Gravitational theories with fixed background fields break diffeomorphism invariance. This breaking can be spontaneous or explicit. A brief summary of the main consequences of these types of breaking is presented. |
0903.4352 | Wlodzimierz Piechocki | Przemyslaw Malkiewicz and Wlodzimierz Piechocki | Energy Scale of the Big Bounce | 5 pages, no figures, version published by Phys Rev D80, 063506 (2009) | Phys.Rev.D80:063506,2009 | 10.1103/PhysRevD.80.063506 | INS 10 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the nature of the cosmological Big Bounce transition within the
loop geometry underlying loop quantum cosmology at classical and quantum
levels. Our canonical quantization method is an alternative to the standard
loop quantum cosmology. An evolution parameter we use has a clear
interpretation. Our method opens the door for analyses of spectra of physical
observables like the energy density and the volume operator. We find that one
cannot determine the energy scale specific to the Big Bounce by making use of
the loop geometry without an extra input from observational cosmology.
| [
{
"created": "Wed, 25 Mar 2009 14:22:39 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Aug 2009 08:06:06 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Sep 2009 09:44:08 GMT",
"version": "v3"
}
] | 2009-09-24 | [
[
"Malkiewicz",
"Przemyslaw",
""
],
[
"Piechocki",
"Wlodzimierz",
""
]
] | We examine the nature of the cosmological Big Bounce transition within the loop geometry underlying loop quantum cosmology at classical and quantum levels. Our canonical quantization method is an alternative to the standard loop quantum cosmology. An evolution parameter we use has a clear interpretation. Our method opens the door for analyses of spectra of physical observables like the energy density and the volume operator. We find that one cannot determine the energy scale specific to the Big Bounce by making use of the loop geometry without an extra input from observational cosmology. |
1807.10343 | S Habib Mazharimousavi | S. Danial Forghani, S. Habib Mazharimousavi and M. Halilsoy | Fate of a Thin-Shell Wormhole Powered by Morris-Thorne Wormhole | 6 pages, one figure | Eur. Phys. J. Plus (2018) 133: 497 | 10.1140/epjp/i2018-12409-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Asymmetric thin-shell wormholes from two traversable Morris-Thorne wormhole
spacetimes, with identical shape but different redshift functions, are
constructed. Energy density of the thin-shell wormhole derives its power from a
Morris-Thorne wormhole which is already exotic. By choice, the weak energy
condition for the thin-shell wormhole is satisfied. A linear barotropic
equation of state is assumed to hold after the radial perturbations. The fate
of our thin-shell wormhole, after the perturbation, is striking: the asymmetric
thin-shell wormhole is destined either to collapse to the original
Morris-Thorne wormhole or expand indefinitely along with the radius of the
throat. In case it collapses to the original wormhole, the result is an
asymmetric Morris-Thorne wormhole. Although this asymmetry does not reflect
into the embedding diagram of the wormhole, passing across the throat, the
wormhole adventurer feels a different redshift function.
| [
{
"created": "Thu, 26 Jul 2018 20:13:38 GMT",
"version": "v1"
}
] | 2019-01-17 | [
[
"Forghani",
"S. Danial",
""
],
[
"Mazharimousavi",
"S. Habib",
""
],
[
"Halilsoy",
"M.",
""
]
] | Asymmetric thin-shell wormholes from two traversable Morris-Thorne wormhole spacetimes, with identical shape but different redshift functions, are constructed. Energy density of the thin-shell wormhole derives its power from a Morris-Thorne wormhole which is already exotic. By choice, the weak energy condition for the thin-shell wormhole is satisfied. A linear barotropic equation of state is assumed to hold after the radial perturbations. The fate of our thin-shell wormhole, after the perturbation, is striking: the asymmetric thin-shell wormhole is destined either to collapse to the original Morris-Thorne wormhole or expand indefinitely along with the radius of the throat. In case it collapses to the original wormhole, the result is an asymmetric Morris-Thorne wormhole. Although this asymmetry does not reflect into the embedding diagram of the wormhole, passing across the throat, the wormhole adventurer feels a different redshift function. |
gr-qc/0403027 | Martin Zofka | M. Zofka | Comments on photonic shells | null | Class.Quant.Grav. 21 (2004) 465-470 | 10.1088/0264-9381/21/2/010 | null | gr-qc | null | We investigate in detail the special case of an infinitely thin static
cylindrical shell composed of counter-rotating photons on circular geodetical
paths separating two distinct parts of Minkowski spacetimes--one inside and the
other outside the shell--and compare it to a static disk shell formed by null
particles counter-rotating on circular geodesics within the shell located
between two sections of flat spacetime. One might ask whether the two cases are
not, in fact, merely one.
| [
{
"created": "Fri, 5 Mar 2004 13:50:10 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Zofka",
"M.",
""
]
] | We investigate in detail the special case of an infinitely thin static cylindrical shell composed of counter-rotating photons on circular geodetical paths separating two distinct parts of Minkowski spacetimes--one inside and the other outside the shell--and compare it to a static disk shell formed by null particles counter-rotating on circular geodesics within the shell located between two sections of flat spacetime. One might ask whether the two cases are not, in fact, merely one. |
2005.09464 | Ali \"Ovg\"un Dr. | Wajiha Javed, Ali Hamza and Ali \"Ovg\"un | Effect of Non-linear Electrodynamics on Weak field deflection angle by
Black Hole | 12 pages. Accepted for publication in Physical Review D
(https://journals.aps.org/prd/abstract/10.1103/PhysRevD.101.103521) | Phys. Rev. D 101, 103521 (2020) | 10.1103/PhysRevD.101.103521 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we investigate the weak deflection angle of light from exact
black hole within the non-linear electrodynamics. First we calculate the
Gaussian optical curvature using the optical spacetime geometry. With the help
of modern geometrical way popularized by Gibbons and Werner, we examine the
deflection angle of light from exact black hole.
For this desire, we determine the optical Gaussian curvature and execute the
Gauss-Bonnet theorem on optical metric and calculate the leading terms of
deflection angle in the weak limit approximation. Furthermore, we likewise
study the plasma medium's effect on weak gravitational lensing by exact black
hole. Hence we expose the effect of the non-linear electrodynamics on the
deflection angle in the weak gravitational field.
| [
{
"created": "Fri, 15 May 2020 20:51:49 GMT",
"version": "v1"
}
] | 2020-05-20 | [
[
"Javed",
"Wajiha",
""
],
[
"Hamza",
"Ali",
""
],
[
"Övgün",
"Ali",
""
]
] | In this work, we investigate the weak deflection angle of light from exact black hole within the non-linear electrodynamics. First we calculate the Gaussian optical curvature using the optical spacetime geometry. With the help of modern geometrical way popularized by Gibbons and Werner, we examine the deflection angle of light from exact black hole. For this desire, we determine the optical Gaussian curvature and execute the Gauss-Bonnet theorem on optical metric and calculate the leading terms of deflection angle in the weak limit approximation. Furthermore, we likewise study the plasma medium's effect on weak gravitational lensing by exact black hole. Hence we expose the effect of the non-linear electrodynamics on the deflection angle in the weak gravitational field. |
gr-qc/0306022 | Sebastian Schlicht | Sebastian Schlicht | Considerations on the Unruh Effect: Causality and Regularization | 19 pages, 2 figures, v2: some minor changes | Class.Quant.Grav. 21 (2004) 4647-4660 | 10.1088/0264-9381/21/19/011 | null | gr-qc | null | This article is motivated by the observation, that calculations of the Unruh
effect based on idealized particle detectors are usually made in a way that
involves integrations along the {\em entire} detector trajectory up to the
infinitely remote {\em future}. We derive an expression which allows
time-dependence of the detector response in the case of a non-stationary
trajectory and conforms more explicitely to the principle of causality, namely
that the response at a given instant of time depends only on the detectors {\em
past} movements. On trying to reproduce the thermal Unruh spectrum we are led
to an unphysical result, which we trace down to the use of the standard
regularization $t\to t-i\eps$ of the correlation function. By consistently
employing a rigid detector of finite extension, we are led to a different
regularization which works fine with our causal response function.
| [
{
"created": "Thu, 5 Jun 2003 13:44:00 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Aug 2003 15:00:59 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Schlicht",
"Sebastian",
""
]
] | This article is motivated by the observation, that calculations of the Unruh effect based on idealized particle detectors are usually made in a way that involves integrations along the {\em entire} detector trajectory up to the infinitely remote {\em future}. We derive an expression which allows time-dependence of the detector response in the case of a non-stationary trajectory and conforms more explicitely to the principle of causality, namely that the response at a given instant of time depends only on the detectors {\em past} movements. On trying to reproduce the thermal Unruh spectrum we are led to an unphysical result, which we trace down to the use of the standard regularization $t\to t-i\eps$ of the correlation function. By consistently employing a rigid detector of finite extension, we are led to a different regularization which works fine with our causal response function. |
1712.06582 | Iber\^e Kuntz | Iber\^e Kuntz | Quantum Corrections to the Gravitational Backreaction | null | null | 10.1140/epjc/s10052-017-5487-0 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Effective Field Theory techniques are used to study the leading order quantum
corrections to the gravitational wave backreaction. The effective stress-energy
tensor is calculated and it is shown that it has a non-vanishing trace that
contributes to the cosmological constant. By comparing the result obtained with
LIGO's data, the first bound on the amplitude of the massive mode is found:
$\epsilon < 1.4\times 10^{-33}$.
| [
{
"created": "Mon, 18 Dec 2017 18:55:23 GMT",
"version": "v1"
}
] | 2018-01-03 | [
[
"Kuntz",
"Iberê",
""
]
] | Effective Field Theory techniques are used to study the leading order quantum corrections to the gravitational wave backreaction. The effective stress-energy tensor is calculated and it is shown that it has a non-vanishing trace that contributes to the cosmological constant. By comparing the result obtained with LIGO's data, the first bound on the amplitude of the massive mode is found: $\epsilon < 1.4\times 10^{-33}$. |
gr-qc/9701022 | James Hartle | James B. Hartle (Institute for Theoretical Physics, University of
California, Santa Barbara) | Quantum Cosmology: Problems for the 21st Century | 18pages, uses REVTEX 3.0, one embedded ps figure, corrected reference | in Proceedings of the 11th Nishinomiya-Yukawa Symposium, ed by K.
Kikkawa, H. Kunitomo, and H. Ohtsubo, World Scientific Singapore, 1998. | null | NSF-ITP-96-141, UCSBTH-96-26 | gr-qc hep-th quant-ph | null | Two fundamental laws are needed for prediction in the universe: (1) a basic
dynamical law and (2) a law for the cosmological initial condition. Quantum
cosmology is the area of basic research concerned with the search for a theory
of the initial cosmological state. The issues involved in this search are
presented in the form of eight problems. (To appear in Physics 2001, ed. by M.
Kumar and in the Proceedings of the 10th Yukawa-Nishinomiya Symposium},
November 7-8, 1996, Nishinomiya, Japan.)
| [
{
"created": "Sat, 11 Jan 1997 00:22:53 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Jan 1997 19:04:11 GMT",
"version": "v2"
}
] | 2008-02-03 | [
[
"Hartle",
"James B.",
"",
"Institute for Theoretical Physics, University of\n California, Santa Barbara"
]
] | Two fundamental laws are needed for prediction in the universe: (1) a basic dynamical law and (2) a law for the cosmological initial condition. Quantum cosmology is the area of basic research concerned with the search for a theory of the initial cosmological state. The issues involved in this search are presented in the form of eight problems. (To appear in Physics 2001, ed. by M. Kumar and in the Proceedings of the 10th Yukawa-Nishinomiya Symposium}, November 7-8, 1996, Nishinomiya, Japan.) |
gr-qc/0308083 | Robin W. Tucker | Robin W. Tucker (Lancaster University UK) | Field-Particle Dynamics in Spacetime Geometries | LaTeX, 28 pages | null | 10.1098/rspa.2004.1311 | null | gr-qc | null | With the aid of a Fermi-Walker chart associated with an orthonormal frame
attached to a time-like curve in spacetime, a discussion is given of
relativistic balance laws that may be used to construct models of massive
particles with spin, electric charge and a magnetic moment,interacting with
background electromagnetic fields and gravitation described by non-Riemannian
geometries. A natural generalisation to relativistic Cosserat media is
immediate.
| [
{
"created": "Tue, 26 Aug 2003 09:15:41 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Tucker",
"Robin W.",
"",
"Lancaster University UK"
]
] | With the aid of a Fermi-Walker chart associated with an orthonormal frame attached to a time-like curve in spacetime, a discussion is given of relativistic balance laws that may be used to construct models of massive particles with spin, electric charge and a magnetic moment,interacting with background electromagnetic fields and gravitation described by non-Riemannian geometries. A natural generalisation to relativistic Cosserat media is immediate. |
2105.11691 | Ilham Prasetyo | I. Prasetyo, H. S. Ramadhan and A. Sulaksono | An Ultra-compact Object from Semi-classical Gravity | 33 pages, 9 figures, accepted for publication in Physical Review D | Phys. Rev. D 103 (2021) 123536 | 10.1103/PhysRevD.103.123536 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In a recent report, Carballo-Rubio [1] utilizes the semi-classical theory of
gravity to obtain a generalized Tolman-Oppenheimer-Volkoff (TOV) equation. This
model has a new coupling constant $l_p$ implying two different modified TOV
equation forms characterized by the sign of $p'$. The negative branch reduces
to the ordinary GR-TOV in the limit of $l_p\to0$, while the positive one does
not. In the positive branch, Carballo-Rubio was able to find the exact
solutions using the constant-$\lambda$ trick. In this work, we investigate
whether this theory's negative branch can also provide a different feature of
the ultra-compact object compared to those obtained from the GR-TOV equation.
We study ultra-compact objects with an isotropically ideal fluid matter where
we use a simple but physically motivated equation of state $\rho=p/w+\rho_0$
with $w$=1 and $w$=1/3. In general, we obtain that the range of $l_p$ is very
restricted and must not be equal to $r_c$. Here $r_c$ is the starting point of
integration located at the center of the star. While $l_p$ should be set to be
much larger than Planck length $L_\text{Pl}$. Consequently, the mass-radius
curves for the various value of $l_p$ for both $w$ cases are still
indistinguishable from the standard GR-TOV results. Hence from the negative
branch of $p'(r)$, the additional free parameter $l_p$ does not provide a
significant effect compared to the standard GR-TOV equation results, even
though $l_p$ is not in the limit of $l_p\to0$ anymore. Therefore, similar to
the conclusion in Ref. [3] with GR theory that the ultra-compact objects from
negative branch of semi-classical gravity with a linear equation of state are
unable to generate demanding gravitational echoes.
| [
{
"created": "Tue, 25 May 2021 06:18:06 GMT",
"version": "v1"
}
] | 2021-06-21 | [
[
"Prasetyo",
"I.",
""
],
[
"Ramadhan",
"H. S.",
""
],
[
"Sulaksono",
"A.",
""
]
] | In a recent report, Carballo-Rubio [1] utilizes the semi-classical theory of gravity to obtain a generalized Tolman-Oppenheimer-Volkoff (TOV) equation. This model has a new coupling constant $l_p$ implying two different modified TOV equation forms characterized by the sign of $p'$. The negative branch reduces to the ordinary GR-TOV in the limit of $l_p\to0$, while the positive one does not. In the positive branch, Carballo-Rubio was able to find the exact solutions using the constant-$\lambda$ trick. In this work, we investigate whether this theory's negative branch can also provide a different feature of the ultra-compact object compared to those obtained from the GR-TOV equation. We study ultra-compact objects with an isotropically ideal fluid matter where we use a simple but physically motivated equation of state $\rho=p/w+\rho_0$ with $w$=1 and $w$=1/3. In general, we obtain that the range of $l_p$ is very restricted and must not be equal to $r_c$. Here $r_c$ is the starting point of integration located at the center of the star. While $l_p$ should be set to be much larger than Planck length $L_\text{Pl}$. Consequently, the mass-radius curves for the various value of $l_p$ for both $w$ cases are still indistinguishable from the standard GR-TOV results. Hence from the negative branch of $p'(r)$, the additional free parameter $l_p$ does not provide a significant effect compared to the standard GR-TOV equation results, even though $l_p$ is not in the limit of $l_p\to0$ anymore. Therefore, similar to the conclusion in Ref. [3] with GR theory that the ultra-compact objects from negative branch of semi-classical gravity with a linear equation of state are unable to generate demanding gravitational echoes. |
2209.04813 | Zacharias Roupas | Zacharias Roupas | The Cosmological Black Hole | Talk given in the 11th International Conference on Mathematical
Modelling in Physical Sciences | AIP Conf. Proc. 2872, 060012 (2023) | 10.1063/5.0162770 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We briefly review the recent novel solution of General Relativity, we call
the cosmological black hole, firstly discovered in [Roupas, Z. Eur. Phys. J. C
82, 255 (2022)]. A dark energy universe and a Schwartzschild black hole are
matched on a common dual event horizon which is finitely thick due to quantum
indeterminacy. The system gets stabilized by a finite tangential pressure
applied on the dual horizon. The fluid entropy of the system at a Tolman
temperature identified with the cosmological horizon temperature is calculated
to be equal with the Bekenstein-Hawking entropy.
| [
{
"created": "Sun, 11 Sep 2022 08:18:33 GMT",
"version": "v1"
}
] | 2024-02-09 | [
[
"Roupas",
"Zacharias",
""
]
] | We briefly review the recent novel solution of General Relativity, we call the cosmological black hole, firstly discovered in [Roupas, Z. Eur. Phys. J. C 82, 255 (2022)]. A dark energy universe and a Schwartzschild black hole are matched on a common dual event horizon which is finitely thick due to quantum indeterminacy. The system gets stabilized by a finite tangential pressure applied on the dual horizon. The fluid entropy of the system at a Tolman temperature identified with the cosmological horizon temperature is calculated to be equal with the Bekenstein-Hawking entropy. |
1510.01925 | Suzanne Lan\'ery | Suzanne Lan\'ery and Thomas Thiemann | Projective Loop Quantum Gravity II. Searching for Semi-Classical States | 51 pages, 1 figure | J. Math. Phys. 58(5):052302 (2017) | 10.1063/1.4983133 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In [arXiv:1411.3592] an extension of the Ashtekar-Lewandowski (AL) state
space of Loop Quantum Gravity was set up with the help a projective formalism
introduced by Kijowski [Kijowski 1977; see also: arXiv:1304.6330,
arXiv:1411.3590]. The motivation for this work was to achieve a more balanced
treatment of the position and momentum variables (aka. holonomies and fluxes).
Indeed, states in the AL Hilbert spaces describe discrete quantum excitations
on top of a vacuum which is an eigenstate of the flux variables (a
`no-geometry' state): in such states, most holonomies are totally spread,
making it difficult to approximate a smooth, classical 4-geometry. However,
going beyond the AL sector does not fully resolve this difficulty: one uncovers
a deeper issue hindering the construction of states semi-classical with respect
to a full set of observables. In the present article, we analyze this issue in
the case of real-valued holonomies (we will briefly comment on the heuristic
implications for other gauge groups, eg. $\mathcal{SU}(2)$). Specifically, we
show that, in this case, there does not exist any state on the holonomy-flux
algebra in which the variances of the holonomies and fluxes observables would
all be finite, let alone small. It is important to note that this obstruction
cannot be bypassed by further enlarging the quantum state space, for it arises
from the structure of the algebra itself: as there are too many (uncountably
many) non-vanishing commutators between the holonomy and flux operators, the
corresponding Heisenberg inequalities force the quantum uncertainties to blow
up uncontrollably. A way out would be to suitably restrict the algebra of
observables. In a companion paper we take the first steps in this direction by
developing a general framework to perform such a restriction without giving up
the universality and diffeomorphism invariance of the theory.
| [
{
"created": "Wed, 7 Oct 2015 12:42:55 GMT",
"version": "v1"
}
] | 2017-05-23 | [
[
"Lanéry",
"Suzanne",
""
],
[
"Thiemann",
"Thomas",
""
]
] | In [arXiv:1411.3592] an extension of the Ashtekar-Lewandowski (AL) state space of Loop Quantum Gravity was set up with the help a projective formalism introduced by Kijowski [Kijowski 1977; see also: arXiv:1304.6330, arXiv:1411.3590]. The motivation for this work was to achieve a more balanced treatment of the position and momentum variables (aka. holonomies and fluxes). Indeed, states in the AL Hilbert spaces describe discrete quantum excitations on top of a vacuum which is an eigenstate of the flux variables (a `no-geometry' state): in such states, most holonomies are totally spread, making it difficult to approximate a smooth, classical 4-geometry. However, going beyond the AL sector does not fully resolve this difficulty: one uncovers a deeper issue hindering the construction of states semi-classical with respect to a full set of observables. In the present article, we analyze this issue in the case of real-valued holonomies (we will briefly comment on the heuristic implications for other gauge groups, eg. $\mathcal{SU}(2)$). Specifically, we show that, in this case, there does not exist any state on the holonomy-flux algebra in which the variances of the holonomies and fluxes observables would all be finite, let alone small. It is important to note that this obstruction cannot be bypassed by further enlarging the quantum state space, for it arises from the structure of the algebra itself: as there are too many (uncountably many) non-vanishing commutators between the holonomy and flux operators, the corresponding Heisenberg inequalities force the quantum uncertainties to blow up uncontrollably. A way out would be to suitably restrict the algebra of observables. In a companion paper we take the first steps in this direction by developing a general framework to perform such a restriction without giving up the universality and diffeomorphism invariance of the theory. |
2312.11908 | Yi Liao | Haiyuan Feng, Yi Liao, and Rong-Jia Yang | Stability of the de-Sitter universe: One-loop nonlocal $f(R)$ gravity | 26 pages,0 figure | JHEP 05 (2024) 115 | 10.1007/JHEP05(2024)115 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | With the method of the background field expansion, we investigate the
one-loop quantization of the Euclidean nonlocal $f(R)$ model in the de-Sitter
universe. We obtain the ghost-free condition (GFC) based on the transformation
from the Jordan frame to the Einstein frame and the classical stability
condition (CSC) satisfied $f^{(0)}_{RR}-\phi_0F^{(0)}_{RR}<0$. We present the
on-shell and off-shell one-loop effective action and quantum stability
condition (QSC) by utilizing the generalized zeta-function. We find that under
the fulfillment of GFC, CSC and QSC are inconsistent.
| [
{
"created": "Tue, 19 Dec 2023 07:30:57 GMT",
"version": "v1"
},
{
"created": "Sat, 11 May 2024 02:02:21 GMT",
"version": "v2"
}
] | 2024-05-14 | [
[
"Feng",
"Haiyuan",
""
],
[
"Liao",
"Yi",
""
],
[
"Yang",
"Rong-Jia",
""
]
] | With the method of the background field expansion, we investigate the one-loop quantization of the Euclidean nonlocal $f(R)$ model in the de-Sitter universe. We obtain the ghost-free condition (GFC) based on the transformation from the Jordan frame to the Einstein frame and the classical stability condition (CSC) satisfied $f^{(0)}_{RR}-\phi_0F^{(0)}_{RR}<0$. We present the on-shell and off-shell one-loop effective action and quantum stability condition (QSC) by utilizing the generalized zeta-function. We find that under the fulfillment of GFC, CSC and QSC are inconsistent. |
gr-qc/0308037 | Ujjal Debnath | Ujjal Debnath, Subenoy Chakraborty | Role of Initial Data in Higher Dimensional Quasi-Spherical Gravitational
Collapse | 7 Latex Pages, RevTex Style, No figures | Gen.Rel.Grav. 37 (2005) 225-232 | 10.1007/s10714-005-0011-5 | null | gr-qc | null | We study the gravitational collapse in ($n+2$)-D quasi-spherical Szekeres
space-time (which possess no killing vectors) with dust as the matter
distribution. Instead of choosing the radial coordinate `$r$' as the initial
value for the scale factor $R$, we consider a power function of $r$ as the
initial scale for the radius $R$. We examine the influence of initial data on
the formation of singularity in gravitational collapse.
| [
{
"created": "Tue, 12 Aug 2003 11:18:39 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Debnath",
"Ujjal",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | We study the gravitational collapse in ($n+2$)-D quasi-spherical Szekeres space-time (which possess no killing vectors) with dust as the matter distribution. Instead of choosing the radial coordinate `$r$' as the initial value for the scale factor $R$, we consider a power function of $r$ as the initial scale for the radius $R$. We examine the influence of initial data on the formation of singularity in gravitational collapse. |
1402.1139 | Jose M. M. Senovilla | Jos\'e M. M. Senovilla | Gravitational double layers | 11 pages, no figures. Minor corrections and some references added.
Typos corrected, new comments and new reference | null | 10.1088/0264-9381/31/7/072002 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I analyze the properties of thin shells through which the scalar curvature R
is discontinuous in gravity theories with R + R^2 Lagrangian on the bulk. These
shells/domain walls are of a new kind because they possess, in addition to the
standard energy-momentum tensor, an external energy flux vector, an external
scalar pressure/tension and, most exotic of all, another energy-momentum tensor
contribution resembling classical dipole distributions on a shell: a double
layer. I prove that all these contributions are necessary to make the entire
energy-momentum tensor divergence-free. This is the first known occurrence of
such a type of double layer allowed in a gravity theory. I present explicit
examples in constant-curvature 5-dimensional bulks, with a brief study of their
properties: new physical behaviors arise.
| [
{
"created": "Wed, 5 Feb 2014 19:43:08 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Feb 2014 19:26:45 GMT",
"version": "v2"
},
{
"created": "Thu, 20 Feb 2014 13:52:10 GMT",
"version": "v3"
}
] | 2015-06-18 | [
[
"Senovilla",
"José M. M.",
""
]
] | I analyze the properties of thin shells through which the scalar curvature R is discontinuous in gravity theories with R + R^2 Lagrangian on the bulk. These shells/domain walls are of a new kind because they possess, in addition to the standard energy-momentum tensor, an external energy flux vector, an external scalar pressure/tension and, most exotic of all, another energy-momentum tensor contribution resembling classical dipole distributions on a shell: a double layer. I prove that all these contributions are necessary to make the entire energy-momentum tensor divergence-free. This is the first known occurrence of such a type of double layer allowed in a gravity theory. I present explicit examples in constant-curvature 5-dimensional bulks, with a brief study of their properties: new physical behaviors arise. |
0905.1654 | Lisa Goggin | The LIGO Scientific Collaboration: B. Abbott, et al | Search for gravitational wave ringdowns from perturbed black holes in
LIGO S4 data | 8 pages, 6 figures | Phys.Rev.D80:062001,2009 | 10.1103/PhysRevD.80.062001 | LIGO-P080093 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | According to general relativity a perturbed black hole will settle to a
stationary configuration by the emission of gravitational radiation. Such a
perturbation will occur, for example, in the coalescence of a black hole
binary, following their inspiral and subsequent merger. At late times the
waveform is a superposition of quasi-normal modes, which we refer to as the
ringdown. The dominant mode is expected to be the fundamental mode, l=m=2.
Since this is a well-known waveform, matched filtering can be implemented to
search for this signal using LIGO data. We present a search for gravitational
waves from black hole ringdowns in the fourth LIGO science run S4, during which
LIGO was sensitive to the dominant mode of perturbed black holes with masses in
the range of 10 Msun to 500 Msun, the regime of intermediate-mass black holes,
to distances up to 300 Mpc. We present a search for gravitational waves from
black hole ringdowns using data from S4. No gravitational wave candidates were
found; we place a 90%-confidence upper limit on the rate of ringdowns from
black holes with mass between 85 Msun and 390 Msun in the local universe,
assuming a uniform distribution of sources, of 3.2 x 10^{-5} yr^{-1} Mpc^{-3} =
1.6 x 10^{-3}yr^{-1} L_{10}^{-1}, where L_{10} is 10^{10} times the solar
blue-light luminosity.
| [
{
"created": "Mon, 11 May 2009 16:59:48 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Aug 2009 19:52:24 GMT",
"version": "v2"
}
] | 2009-09-24 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"Abbott",
"B.",
""
]
] | According to general relativity a perturbed black hole will settle to a stationary configuration by the emission of gravitational radiation. Such a perturbation will occur, for example, in the coalescence of a black hole binary, following their inspiral and subsequent merger. At late times the waveform is a superposition of quasi-normal modes, which we refer to as the ringdown. The dominant mode is expected to be the fundamental mode, l=m=2. Since this is a well-known waveform, matched filtering can be implemented to search for this signal using LIGO data. We present a search for gravitational waves from black hole ringdowns in the fourth LIGO science run S4, during which LIGO was sensitive to the dominant mode of perturbed black holes with masses in the range of 10 Msun to 500 Msun, the regime of intermediate-mass black holes, to distances up to 300 Mpc. We present a search for gravitational waves from black hole ringdowns using data from S4. No gravitational wave candidates were found; we place a 90%-confidence upper limit on the rate of ringdowns from black holes with mass between 85 Msun and 390 Msun in the local universe, assuming a uniform distribution of sources, of 3.2 x 10^{-5} yr^{-1} Mpc^{-3} = 1.6 x 10^{-3}yr^{-1} L_{10}^{-1}, where L_{10} is 10^{10} times the solar blue-light luminosity. |
gr-qc/0105055 | Avraham E. Mayo | Jacob D. Bekenstein and Avraham E. Mayo | Black holes are one-dimensional | 5 pages, REVTEX, This essay received Second Award in the Annual Essay
Competition of the Gravity Research Foundation for the year 2001 | Gen.Rel.Grav. 33 (2001) 2095-2099 | 10.1023/A:1015278813573 | null | gr-qc | null | The holographic principle has revealed that physical systems in 3-D space,
black holes included, are basically two-dimensional as far as their information
content is concerned. This conclusion is complemented by one sketched here: as
far as entropy or information flow is concerned, a black hole behaves as a
one-dimensional channel. We define a channel in flat spacetime in thermodynamic
terms, and contrast it with common entropy emitting systems. A black hole is
more like the former: its entropy output is related to the emitted power as it
would be for a one-dimensional channel, and disposal of an information stream
down a black hole is limited by the power invested in the same way as for a
one-dimensional channel.
| [
{
"created": "Thu, 17 May 2001 07:24:19 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Bekenstein",
"Jacob D.",
""
],
[
"Mayo",
"Avraham E.",
""
]
] | The holographic principle has revealed that physical systems in 3-D space, black holes included, are basically two-dimensional as far as their information content is concerned. This conclusion is complemented by one sketched here: as far as entropy or information flow is concerned, a black hole behaves as a one-dimensional channel. We define a channel in flat spacetime in thermodynamic terms, and contrast it with common entropy emitting systems. A black hole is more like the former: its entropy output is related to the emitted power as it would be for a one-dimensional channel, and disposal of an information stream down a black hole is limited by the power invested in the same way as for a one-dimensional channel. |
1311.2800 | Rong-Jia Yang | Rong-Jia Yang, Bohai Chen, Haijun Zhao, Jun Li, Yuan Liu | Test of conformal gravity with astrophysical observations | 6 pages, 2 figures | Phys. Lett. B 727 (2013) 43 | 10.1016/j.physletb.2013.10.035 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Since it can describe the rotation curves of galaxies without dark matter and
can give rise to accelerated expansion, conformal gravity attracts much
attention recently. As a theory of modified gravity, it is important to test
conformal gravity with astrophysical observations. Here we constrain conformal
gravity with SNIa and Hubble parameter data and investigate whether it suffers
from an age problem with the age of APM~08279+5255. We find conformal gravity
can accommodate the age of APM~08279+5255 at 3 $\sigma$ deviation, unlike most
of dark energy models which suffer from an age problem.
| [
{
"created": "Tue, 12 Nov 2013 14:59:17 GMT",
"version": "v1"
}
] | 2014-05-28 | [
[
"Yang",
"Rong-Jia",
""
],
[
"Chen",
"Bohai",
""
],
[
"Zhao",
"Haijun",
""
],
[
"Li",
"Jun",
""
],
[
"Liu",
"Yuan",
""
]
] | Since it can describe the rotation curves of galaxies without dark matter and can give rise to accelerated expansion, conformal gravity attracts much attention recently. As a theory of modified gravity, it is important to test conformal gravity with astrophysical observations. Here we constrain conformal gravity with SNIa and Hubble parameter data and investigate whether it suffers from an age problem with the age of APM~08279+5255. We find conformal gravity can accommodate the age of APM~08279+5255 at 3 $\sigma$ deviation, unlike most of dark energy models which suffer from an age problem. |
1503.06539 | Shinji Tsujikawa | Antonio De Felice, Kazuya Koyama, Shinji Tsujikawa | Observational signatures of the theories beyond Horndeski | 20 pages, 4 figures, published in JCAP | JCAP 1505 (2015) 058 | 10.1088/1475-7516/2015/05/058 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the approach of the effective field theory of modified gravity, we derive
the equations of motion for linear perturbations in the presence of a
barotropic perfect fluid on the flat isotropic cosmological background. In a
simple version of Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories, which is
the minimum extension of Horndeski theories, we show that a slight deviation of
the tensor propagation speed squared $c_{\rm t}^2$ from 1 generally leads to
the large modification to the propagation speed squared $c_{\rm s}^2$ of a
scalar degree of freedom $\phi$. This problem persists whenever the kinetic
energy $\rho_X$ of the field $\phi$ is much smaller than the background energy
density $\rho_m$, which is the case for most of dark energy models in the
asymptotic past. Since the scaling solution characterized by the constant ratio
$\rho_X/\rho_m$ is one way out for avoiding such a problem, we study the
evolution of perturbations for a scaling dark energy model in the framework of
GLPV theories in the Jordan frame. Provided the oscillating mode of scalar
perturbations is fine-tuned so that it is initially suppressed, the anisotropic
parameter $\eta=-\Phi/\Psi$ between the two gravitational potentials $\Psi$ and
$\Phi$ significantly deviates from 1 for $c_{\rm t}^2$ away from 1. For other
general initial conditions, the deviation of $c_{\rm t}^2$ from 1 gives rise to
the large oscillation of $\Psi$ with the frequency related to $c_{\rm s}^2$. In
both cases, the model can leave distinct imprints for the observations of CMB
and weak lensing.
| [
{
"created": "Mon, 23 Mar 2015 06:19:43 GMT",
"version": "v1"
},
{
"created": "Thu, 28 May 2015 15:02:46 GMT",
"version": "v2"
}
] | 2015-05-29 | [
[
"De Felice",
"Antonio",
""
],
[
"Koyama",
"Kazuya",
""
],
[
"Tsujikawa",
"Shinji",
""
]
] | In the approach of the effective field theory of modified gravity, we derive the equations of motion for linear perturbations in the presence of a barotropic perfect fluid on the flat isotropic cosmological background. In a simple version of Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories, which is the minimum extension of Horndeski theories, we show that a slight deviation of the tensor propagation speed squared $c_{\rm t}^2$ from 1 generally leads to the large modification to the propagation speed squared $c_{\rm s}^2$ of a scalar degree of freedom $\phi$. This problem persists whenever the kinetic energy $\rho_X$ of the field $\phi$ is much smaller than the background energy density $\rho_m$, which is the case for most of dark energy models in the asymptotic past. Since the scaling solution characterized by the constant ratio $\rho_X/\rho_m$ is one way out for avoiding such a problem, we study the evolution of perturbations for a scaling dark energy model in the framework of GLPV theories in the Jordan frame. Provided the oscillating mode of scalar perturbations is fine-tuned so that it is initially suppressed, the anisotropic parameter $\eta=-\Phi/\Psi$ between the two gravitational potentials $\Psi$ and $\Phi$ significantly deviates from 1 for $c_{\rm t}^2$ away from 1. For other general initial conditions, the deviation of $c_{\rm t}^2$ from 1 gives rise to the large oscillation of $\Psi$ with the frequency related to $c_{\rm s}^2$. In both cases, the model can leave distinct imprints for the observations of CMB and weak lensing. |
gr-qc/9610011 | Piotr Chrusciel | Piotr T. Chru\'sciel | On rigidity of analytic black holes | 10 pages, latex with amssymb | Commun.Math.Phys. 189 (1997) 1-7 | 10.1007/s002200050187 | null | gr-qc | null | We establish global extendibility (to the domain of outer communications) of
locally defined isometries of appropriately regular analytic black holes. This
allows us to fill a gap in the Hawking-Ellis proof of black-hole rigidity.
| [
{
"created": "Wed, 9 Oct 1996 11:20:52 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Chruściel",
"Piotr T.",
""
]
] | We establish global extendibility (to the domain of outer communications) of locally defined isometries of appropriately regular analytic black holes. This allows us to fill a gap in the Hawking-Ellis proof of black-hole rigidity. |
gr-qc/0007007 | Sergei M. Kopeikin | Sergei M. Kopeikin (University of Missouri-Columbia, USA), N.V.
Shuygina, M.V. Vasilyev, E.I. Yagudina (Institute of Applied Astronomy,
Russia), L.I. Yagudin (Pulkovo Observatory, Russia) | Numerical Data-Processing Simulations of Microarcsecond Classical and
Relativistic Effects in Space Astrometry | 5 pages, the talk given at the IAU Coll. 180 "Towards Models and
Constants for Sub-Microarcsecond Astrometry", Washington DC, March 26 - April
2, 2000 | null | null | null | gr-qc astro-ph | null | The accuracy of astrometric observations conducted via a space-borne optical
interferometer orbiting the Earth is expected to approach a few
microarcseconds. Data processing of such extremely high-precision measurements
requires access to a rigorous relativistic model of light ray propagation
developed in the framework of General Relativity. The data-processing of the
space interferometric observations must rely upon the theory of
general-relativistic transformations between the spacecraft, geocentric, and
solar barycentric reference systems allowing unique and unambiguous
interpretation of the stellar aberration and parallax effects. On the other
hand, the algorithm must also include physically adequate treatment of the
relativistic effect of light deflection caused by the spherically-symmetric
(monopole-dependent) part of the gravitational field of the Sun and planets as
well as the quadrupole- and spin-dependent counterparts of it. In some
particular cases the gravitomagnetic field induced by the translational motion
of the Sun and planets should be also taken into account for unambigious
prediction of the light-ray deflection angle. In the present paper we describe
the corresponding software program for taking into account all classical
(proper motion, parallax, etc.) and relativistic (aberration, deflection of
light) effects up to the microarcsecond threshold and demonstrate, using
numerical simulations, how observations of stars and/or quasars conducted on
board a space optical interferometer orbiting the Earth can be processed and
disentangled.
| [
{
"created": "Wed, 5 Jul 2000 17:15:54 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Kopeikin",
"Sergei M.",
"",
"University of Missouri-Columbia, USA"
],
[
"Shuygina",
"N. V.",
"",
"Institute of Applied Astronomy,\n Russia"
],
[
"Vasilyev",
"M. V.",
"",
"Institute of Applied Astronomy,\n Russia"
],
[
"Yagudina",
"E. I.",
... | The accuracy of astrometric observations conducted via a space-borne optical interferometer orbiting the Earth is expected to approach a few microarcseconds. Data processing of such extremely high-precision measurements requires access to a rigorous relativistic model of light ray propagation developed in the framework of General Relativity. The data-processing of the space interferometric observations must rely upon the theory of general-relativistic transformations between the spacecraft, geocentric, and solar barycentric reference systems allowing unique and unambiguous interpretation of the stellar aberration and parallax effects. On the other hand, the algorithm must also include physically adequate treatment of the relativistic effect of light deflection caused by the spherically-symmetric (monopole-dependent) part of the gravitational field of the Sun and planets as well as the quadrupole- and spin-dependent counterparts of it. In some particular cases the gravitomagnetic field induced by the translational motion of the Sun and planets should be also taken into account for unambigious prediction of the light-ray deflection angle. In the present paper we describe the corresponding software program for taking into account all classical (proper motion, parallax, etc.) and relativistic (aberration, deflection of light) effects up to the microarcsecond threshold and demonstrate, using numerical simulations, how observations of stars and/or quasars conducted on board a space optical interferometer orbiting the Earth can be processed and disentangled. |
1906.10708 | Abraham Harte | Abraham I. Harte | Gravitational lensing beyond geometric optics: II. Metric independence | 37 pages, 1 figure | Gen. Rel. Grav. 51:160 (2019) | 10.1007/s10714-019-2646-7 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Typical applications of gravitational lensing use the properties of
electromagnetic or gravitational waves to infer the geometry through which
those waves propagate. Nevertheless, the optical fields themselves - as opposed
to their interactions with material bodies - encode very little of that
geometry: It is shown here that any given configuration is compatible with a
very large variety of spacetime metrics. For scalar fields in geometric optics,
or observables which are not sensitive to the detailed polarization content of
electromagnetic or gravitational waves, seven of the ten metric components are
essentially irrelevant. With polarization, five components are irrelevant. In
the former case, this result together with diffeomorphism invariance allows
essentially any geometric-optics configuration associated with a particular
spacetime to be embedded into any other spacetime, at least in finite regions.
Going beyond the geometric-optics approximation breaks some of this degeneracy,
although much remains even then. Overall, high-frequency wave propagation is
shown to be insensitive to compositions of certain conformal, Kerr-Schild, and
related transformations of the background metric. One application is that new
solutions for scalar, electromagnetic, and gravitational waves may be generated
from old ones. In one example described here, the high-frequency scattering of
a plane wave by a point mass is computed by transforming a plane wave in flat
spacetime.
| [
{
"created": "Tue, 25 Jun 2019 18:00:56 GMT",
"version": "v1"
},
{
"created": "Sun, 8 Dec 2019 10:40:51 GMT",
"version": "v2"
}
] | 2019-12-10 | [
[
"Harte",
"Abraham I.",
""
]
] | Typical applications of gravitational lensing use the properties of electromagnetic or gravitational waves to infer the geometry through which those waves propagate. Nevertheless, the optical fields themselves - as opposed to their interactions with material bodies - encode very little of that geometry: It is shown here that any given configuration is compatible with a very large variety of spacetime metrics. For scalar fields in geometric optics, or observables which are not sensitive to the detailed polarization content of electromagnetic or gravitational waves, seven of the ten metric components are essentially irrelevant. With polarization, five components are irrelevant. In the former case, this result together with diffeomorphism invariance allows essentially any geometric-optics configuration associated with a particular spacetime to be embedded into any other spacetime, at least in finite regions. Going beyond the geometric-optics approximation breaks some of this degeneracy, although much remains even then. Overall, high-frequency wave propagation is shown to be insensitive to compositions of certain conformal, Kerr-Schild, and related transformations of the background metric. One application is that new solutions for scalar, electromagnetic, and gravitational waves may be generated from old ones. In one example described here, the high-frequency scattering of a plane wave by a point mass is computed by transforming a plane wave in flat spacetime. |
1001.0550 | \"Ozg\"ur Akarsu | Ozgur Akarsu, Can B. Kilinc | de Sitter expansion with anisotropic fluid in Bianchi type-I space-time | 9 pages. Some corrections made in text and references in v2 | Astrophysics and Space Science, 326 (2010) 315-322 | 10.1007/s10509-009-0254-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Some features of the Bianchi type-I universes in the presence of a fluid that
wields an anisotropic equation of state (EoS) parameter are discussed in the
context of general relativity. The models that exhibit de Sitter volumetric
expansion due to the constant effective energy density (the sum of the energy
density of the fluid and the anisotropy energy density) are of particular
interest. We also introduce two locally rotationally symmetric models, which
exhibit de Sitter volumetric expansion in the presence of a hypothetical fluid
that has been obtained by minimally altering the conventional vacuum energy. In
the first model, the directional EoS parameter on the x axis is assumed to be
-1, while the ones on the other axes and the energy density of the fluid are
allowed to be functions of time. In the second model, the energy density of the
fluid is assumed to be constant, while the directional EoS parameters are
allowed to be functions of time.
| [
{
"created": "Mon, 4 Jan 2010 18:20:56 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Jan 2010 17:40:50 GMT",
"version": "v2"
}
] | 2010-03-02 | [
[
"Akarsu",
"Ozgur",
""
],
[
"Kilinc",
"Can B.",
""
]
] | Some features of the Bianchi type-I universes in the presence of a fluid that wields an anisotropic equation of state (EoS) parameter are discussed in the context of general relativity. The models that exhibit de Sitter volumetric expansion due to the constant effective energy density (the sum of the energy density of the fluid and the anisotropy energy density) are of particular interest. We also introduce two locally rotationally symmetric models, which exhibit de Sitter volumetric expansion in the presence of a hypothetical fluid that has been obtained by minimally altering the conventional vacuum energy. In the first model, the directional EoS parameter on the x axis is assumed to be -1, while the ones on the other axes and the energy density of the fluid are allowed to be functions of time. In the second model, the energy density of the fluid is assumed to be constant, while the directional EoS parameters are allowed to be functions of time. |
0806.4340 | Emanuel Gallo | Emanuel Gallo, Luis Lehner and Osvaldo Moreschi | Estimating total momentum at finite distances | 10 pages, 1 figure. Typos corrected. Comments added and a new
Appendix. To be published in PRD | Phys.Rev.D78:084027,2008 | 10.1103/PhysRevD.78.084027 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the difficulties associated with the evaluation of the total Bondi
momentum at finite distances around the central source of a general
(asymptotically flat) spacetime. Since the total momentum is only rigorously
defined at future null infinity, both finite distance and gauge effects must be
taken into account for a correct computation of this quantity.
Our discussion is applicable in general contexts but is particularly relevant
in numerically constructed spacetimes for both extracting important physical
information and assessing the accuracy of additional quantities.
| [
{
"created": "Thu, 26 Jun 2008 15:20:40 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Sep 2008 18:51:28 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Gallo",
"Emanuel",
""
],
[
"Lehner",
"Luis",
""
],
[
"Moreschi",
"Osvaldo",
""
]
] | We study the difficulties associated with the evaluation of the total Bondi momentum at finite distances around the central source of a general (asymptotically flat) spacetime. Since the total momentum is only rigorously defined at future null infinity, both finite distance and gauge effects must be taken into account for a correct computation of this quantity. Our discussion is applicable in general contexts but is particularly relevant in numerically constructed spacetimes for both extracting important physical information and assessing the accuracy of additional quantities. |
1812.02394 | Mykhailo Konchatnij | Yu. L. Bolotin, V. A. Cherkaskiy, O.Yu. Ivashtenko, M. I. Konchatnyi,
L. G. Zazunov | APPLIED COSMOGRAPHY: A Pedagogical Review | 66 pages, 4 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on the cosmological principle only, the method of describing the
evolution of the Universe, called cosmography, is in fact a kinematics of
cosmological expansion. The effectiveness of cosmography lies in the fact that
it allows, based on the results of observations, to perform a rigid selection
of models that do not contradict the cosmological principle. It is important
that the introduction of new components (dark matter, dark energy or even more
mysterious entities) will not affect the relationship between the kinematic
characteristics (cosmographic parameters) This paper shows that within the
framework of cosmography the parameters of any model that satisfies the
cosmological principle (the universe is homogeneous and isotropic on large
scale), can be expressed through cosmographic parameters. The proposed approach
to finding the parameters of cosmological models has many advantages. Emphasize
that all the obtained results are accurate, since they follow from identical
transformations. The procedure can be generalized to the case of models with
interaction between components.
| [
{
"created": "Thu, 6 Dec 2018 07:59:33 GMT",
"version": "v1"
}
] | 2018-12-07 | [
[
"Bolotin",
"Yu. L.",
""
],
[
"Cherkaskiy",
"V. A.",
""
],
[
"Ivashtenko",
"O. Yu.",
""
],
[
"Konchatnyi",
"M. I.",
""
],
[
"Zazunov",
"L. G.",
""
]
] | Based on the cosmological principle only, the method of describing the evolution of the Universe, called cosmography, is in fact a kinematics of cosmological expansion. The effectiveness of cosmography lies in the fact that it allows, based on the results of observations, to perform a rigid selection of models that do not contradict the cosmological principle. It is important that the introduction of new components (dark matter, dark energy or even more mysterious entities) will not affect the relationship between the kinematic characteristics (cosmographic parameters) This paper shows that within the framework of cosmography the parameters of any model that satisfies the cosmological principle (the universe is homogeneous and isotropic on large scale), can be expressed through cosmographic parameters. The proposed approach to finding the parameters of cosmological models has many advantages. Emphasize that all the obtained results are accurate, since they follow from identical transformations. The procedure can be generalized to the case of models with interaction between components. |
gr-qc/0102080 | Tsukasa Murata | Tsukasa Murata, Keiji Tsunoda, Kazuhiro Yamamoto (Hiroshima Univ.) | Explicit Derivation of the Fluctuation-Dissipation Relation of the
Vacuum Noise in the N-dimensional de Sitter Spacetime | 22 pages including 2 figures, to be published in Int. J. Mod. Phys. A | null | 10.1142/S0217751X01004244 | HUPD-0010 | gr-qc hep-ph hep-th | null | Motivated by a recent work by Terashima (Phys. Rev. D60 084001), we revisit
the fluctuation-dissipation (FD) relation between the dissipative coefficient
of a detector and the vacuum noise of fields in curved spacetime. In an
explicit manner we show that the dissipative coefficient obtained from
classical equations of motion of the detector and the scalar (or Dirac) field
satisfies the FD relation associated with the vacuum noise of the field, which
demonstrates that the Terashima's prescription works properly in the
$N$-dimensional de Sitter spacetime. This practice is useful not only to
reconfirm the validity of the use of the retarded Green function to evaluate
the dissipative coefficient from the classical equations of motion but also to
understand why the derivation works properly, which is discussed in connection
with previous investigations on the basis on the Kubo-Martin-Schwinger (KMS)
condition. Possible application to black hole spacetime is also briefly
discussed.
| [
{
"created": "Mon, 19 Feb 2001 04:37:44 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Murata",
"Tsukasa",
"",
"Hiroshima Univ."
],
[
"Tsunoda",
"Keiji",
"",
"Hiroshima Univ."
],
[
"Yamamoto",
"Kazuhiro",
"",
"Hiroshima Univ."
]
] | Motivated by a recent work by Terashima (Phys. Rev. D60 084001), we revisit the fluctuation-dissipation (FD) relation between the dissipative coefficient of a detector and the vacuum noise of fields in curved spacetime. In an explicit manner we show that the dissipative coefficient obtained from classical equations of motion of the detector and the scalar (or Dirac) field satisfies the FD relation associated with the vacuum noise of the field, which demonstrates that the Terashima's prescription works properly in the $N$-dimensional de Sitter spacetime. This practice is useful not only to reconfirm the validity of the use of the retarded Green function to evaluate the dissipative coefficient from the classical equations of motion but also to understand why the derivation works properly, which is discussed in connection with previous investigations on the basis on the Kubo-Martin-Schwinger (KMS) condition. Possible application to black hole spacetime is also briefly discussed. |
1711.01925 | Houri Ziaeepour | Houri Ziaeepour | Non-equilibrium evolution of quantum fields during inflation and late
accelerating expansion | 57 pages, 16 figures | null | null | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | To understand mechanisms leading to inflation and late acceleration of the
Universe it is important to see how one or a set of quantum fields may evolve
such that the classical energy-momentum tensor behave similar to a cosmological
constant. In this work we consider a toy model including 3 scalar fields with
very different masses to study the formation of a light axion-like condensate,
presumed to be responsible for inflation and/or late accelerating expansion of
the Universe. Despite its simplicity, this model reflects hierarchy of masses
and couplings of the Standard Model and its candidate extensions. The
investigation is performed in the framework of non-equilibrium quantum field
theory in a consistently evolved FLRW geometry. We discuss in details how the
initial conditions for such a model must be defined in a fully quantum setup
and show that in a multi-component model interactions reduce the number of
independent initial degrees of freedom. Numerical simulation of this model
shows that it can be fully consistent with present cosmological observations.
For the chosen range of parameters we find that quantum interactions rather
than effective potential of a condensate is the dominant contributor in the
energy density of the Universe and triggers both inflation and late
accelerating expansion. Nonetheless, despite its small contribution in the
energy density, the light scalar field - in both condensate and quasi free
particle forms - has a crucial role in controlling the trend of heavier fields.
Furthermore, up to precision of our simulations we do not find any IR
singularity during inflation. These findings highlight uncertainties in
attempts to extract information about physics of the early Universe by naively
comparing predictions of local effective classical models with cosmological
observations, neglecting inherently non-local nature of quantum processes.
| [
{
"created": "Fri, 3 Nov 2017 15:06:35 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Feb 2018 10:10:27 GMT",
"version": "v2"
},
{
"created": "Sun, 15 Jul 2018 13:42:06 GMT",
"version": "v3"
}
] | 2018-07-17 | [
[
"Ziaeepour",
"Houri",
""
]
] | To understand mechanisms leading to inflation and late acceleration of the Universe it is important to see how one or a set of quantum fields may evolve such that the classical energy-momentum tensor behave similar to a cosmological constant. In this work we consider a toy model including 3 scalar fields with very different masses to study the formation of a light axion-like condensate, presumed to be responsible for inflation and/or late accelerating expansion of the Universe. Despite its simplicity, this model reflects hierarchy of masses and couplings of the Standard Model and its candidate extensions. The investigation is performed in the framework of non-equilibrium quantum field theory in a consistently evolved FLRW geometry. We discuss in details how the initial conditions for such a model must be defined in a fully quantum setup and show that in a multi-component model interactions reduce the number of independent initial degrees of freedom. Numerical simulation of this model shows that it can be fully consistent with present cosmological observations. For the chosen range of parameters we find that quantum interactions rather than effective potential of a condensate is the dominant contributor in the energy density of the Universe and triggers both inflation and late accelerating expansion. Nonetheless, despite its small contribution in the energy density, the light scalar field - in both condensate and quasi free particle forms - has a crucial role in controlling the trend of heavier fields. Furthermore, up to precision of our simulations we do not find any IR singularity during inflation. These findings highlight uncertainties in attempts to extract information about physics of the early Universe by naively comparing predictions of local effective classical models with cosmological observations, neglecting inherently non-local nature of quantum processes. |
1905.02454 | Alessandro Tronconi | A.Y. Kamenshchik, A. Tronconi, G. Venturi | Induced Gravity and Quantum Cosmology | 8 pages, no figures | Phys. Rev. D 100, 023521 (2019) | 10.1103/PhysRevD.100.023521 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the Wheeler-DeWitt equation for a class of induced gravity models in
the minisuperspace approximation. In such models a scalar field nonminimally
coupled to gravity determines the effective Newton's constant. For simplicity
our analysis is limited to power-law potentials for the scalar field which have
exact classical solutions. We show that these models have exact solutions also
when quantised. Finally the Einstein Frame form of these solutions is obtained
and a classical-quantum correspondence is found. Realistic induced gravity
models also must include a symmetry breaking term which is needed in order to
obtain a gravitational constant, successful inflation and a subsequent standard
cosmological evolution. Nonetheless the potentials considered are important as
they may describe the inflationary phase when the symmetry breaking part of the
potential is negligible.
| [
{
"created": "Tue, 7 May 2019 10:32:10 GMT",
"version": "v1"
}
] | 2019-07-24 | [
[
"Kamenshchik",
"A. Y.",
""
],
[
"Tronconi",
"A.",
""
],
[
"Venturi",
"G.",
""
]
] | We study the Wheeler-DeWitt equation for a class of induced gravity models in the minisuperspace approximation. In such models a scalar field nonminimally coupled to gravity determines the effective Newton's constant. For simplicity our analysis is limited to power-law potentials for the scalar field which have exact classical solutions. We show that these models have exact solutions also when quantised. Finally the Einstein Frame form of these solutions is obtained and a classical-quantum correspondence is found. Realistic induced gravity models also must include a symmetry breaking term which is needed in order to obtain a gravitational constant, successful inflation and a subsequent standard cosmological evolution. Nonetheless the potentials considered are important as they may describe the inflationary phase when the symmetry breaking part of the potential is negligible. |
1810.07060 | Yoshinta Setyawati | Yoshinta Eka Setyawati, Frank Ohme, Sebastian Khan | Enhancing gravitational waveform models through dynamic calibration | 14 pages, 13 figures | Phys. Rev. D 99, 024010 (2019) | 10.1103/PhysRevD.99.024010 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Strategies to model the inspiral, merger and ringdown gravitational waveform
of coalescing binaries are restricted in parameter space by the coverage of
available numerical-relativity simulations. When more numerical waveforms
become available, substantial efforts to manually (re-)calibrate models are
required. The aim of this study is to overcome these limitations. We explore a
method to combine the information of two waveform models: an accurate, but
computationally expensive target model, and a fast but less accurate
approximate model. In an automatic process we systematically update the basis
representation of the approximate model using information from the target model
and call the new model as the enriched basis. This new model can be evaluated
anywhere in the parameter space jointly covered by either the approximate or
target model, and the enriched basis model is considerably more accurate in
regions where the sparse target signals were available. Here we show a
proof-of-concept construction of signals from non-precessing, spinning
black-hole binaries based on the phenomenological waveform family. We show that
obvious shortcomings of the previous PhenomB being the approximate model in the
region of unequal masses and unequal spins can be corrected by combining its
basis with interpolated projection coefficients derived from the more recent
and accurate PhenomD as the target model. Our success in building such a model
constitutes an major step towards dynamically combining numerical relativity
data and analytical waveform models in the computationally demanding analysis
of LIGO and Virgo data.
| [
{
"created": "Tue, 16 Oct 2018 15:03:54 GMT",
"version": "v1"
}
] | 2019-01-10 | [
[
"Setyawati",
"Yoshinta Eka",
""
],
[
"Ohme",
"Frank",
""
],
[
"Khan",
"Sebastian",
""
]
] | Strategies to model the inspiral, merger and ringdown gravitational waveform of coalescing binaries are restricted in parameter space by the coverage of available numerical-relativity simulations. When more numerical waveforms become available, substantial efforts to manually (re-)calibrate models are required. The aim of this study is to overcome these limitations. We explore a method to combine the information of two waveform models: an accurate, but computationally expensive target model, and a fast but less accurate approximate model. In an automatic process we systematically update the basis representation of the approximate model using information from the target model and call the new model as the enriched basis. This new model can be evaluated anywhere in the parameter space jointly covered by either the approximate or target model, and the enriched basis model is considerably more accurate in regions where the sparse target signals were available. Here we show a proof-of-concept construction of signals from non-precessing, spinning black-hole binaries based on the phenomenological waveform family. We show that obvious shortcomings of the previous PhenomB being the approximate model in the region of unequal masses and unequal spins can be corrected by combining its basis with interpolated projection coefficients derived from the more recent and accurate PhenomD as the target model. Our success in building such a model constitutes an major step towards dynamically combining numerical relativity data and analytical waveform models in the computationally demanding analysis of LIGO and Virgo data. |
gr-qc/0410104 | J. Daniel Christensen | J. Daniel Christensen, Louis Crane | Causal sites as quantum geometry | 21 pages, 3 eps figures; v2: added references; to appear in JMP | J.Math.Phys. 46 (2005) 122502 | 10.1063/1.2138043 | null | gr-qc math.CT | null | We propose a structure called a causal site to use as a setting for quantum
geometry, replacing the underlying point set. The structure has an interesting
categorical form, and a natural "tangent 2-bundle," analogous to the tangent
bundle of a smooth manifold. Examples with reasonable finiteness conditions
have an intrinsic geometry, which can approximate classical solutions to
general relativity. We propose an approach to quantization of causal sites as
well.
| [
{
"created": "Wed, 20 Oct 2004 20:36:48 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Sep 2005 19:50:33 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Christensen",
"J. Daniel",
""
],
[
"Crane",
"Louis",
""
]
] | We propose a structure called a causal site to use as a setting for quantum geometry, replacing the underlying point set. The structure has an interesting categorical form, and a natural "tangent 2-bundle," analogous to the tangent bundle of a smooth manifold. Examples with reasonable finiteness conditions have an intrinsic geometry, which can approximate classical solutions to general relativity. We propose an approach to quantization of causal sites as well. |
gr-qc/0310095 | Donald Salisbury | D. C. Salisbury | Gauge Fixing and Observables in General Relativity | Contribution to the Proceedings of Spacetime and Fundamental
Interactions: Quantum Aspects, May, 2003, honoring the 65'th birthday of A.
P. Balachandran | Mod.Phys.Lett. A18 (2003) 2475-2482 | 10.1142/S0217732303012714 | null | gr-qc | null | The conventional group of four-dimensional diffeomorphisms is not realizeable
as a canonical transformation group in phase space. Yet there is a larger
field-dependent symmetry transformation group which does faithfully reproduce
4-D diffeomorphism symmetries. Some properties of this group were first
explored by Bergmann and Komar. More recently the group has been analyzed from
the perspective of projectability under the Legendre map. Time translation is
not a realizeable symmetry, and is therefore distinct from
diffeomorphism-induced symmetries. This issue is explored further in this
paper. It is shown that time is not "frozen". Indeed, time-like diffeomorphism
invariants must be time-dependent. Intrinsic coordinates of the type proposed
by Bergmann and Komar are used to construct invariants. Lapse and shift
variables are retained as canonical variables in this approach, and therefore
will be subject to quantum fluctuations in an eventual quantum theory. Concepts
and constructions are illustrated using the relativistic classical and quantum
free particle. In this example concrete time-dependent invariants are displayed
and fluctuation in proper time is manifest.
| [
{
"created": "Sun, 19 Oct 2003 21:52:34 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Salisbury",
"D. C.",
""
]
] | The conventional group of four-dimensional diffeomorphisms is not realizeable as a canonical transformation group in phase space. Yet there is a larger field-dependent symmetry transformation group which does faithfully reproduce 4-D diffeomorphism symmetries. Some properties of this group were first explored by Bergmann and Komar. More recently the group has been analyzed from the perspective of projectability under the Legendre map. Time translation is not a realizeable symmetry, and is therefore distinct from diffeomorphism-induced symmetries. This issue is explored further in this paper. It is shown that time is not "frozen". Indeed, time-like diffeomorphism invariants must be time-dependent. Intrinsic coordinates of the type proposed by Bergmann and Komar are used to construct invariants. Lapse and shift variables are retained as canonical variables in this approach, and therefore will be subject to quantum fluctuations in an eventual quantum theory. Concepts and constructions are illustrated using the relativistic classical and quantum free particle. In this example concrete time-dependent invariants are displayed and fluctuation in proper time is manifest. |
1902.02128 | Gabriele Barca | Gabriele Barca, Paolo Di Antonio, Giovanni Montani, Alberto Patti | Semiclassical and Quantum Polymer Effects in the Flat Isotropic Universe | New submission to match published version | Phys. Rev. D 99, 123509 (2019) | 10.1103/PhysRevD.99.123509 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze some relevant semiclassical and quantum features of the
implementation of Polymer Quantum Mechanics to the phenomenology of the flat
isotropic Universe.
We firstly investigate a parallelism between the semiclassical polymer
dynamics of the flat isotropic Universe, as reduced to the effect of a modified
simplectic structure, and the so-called Generalized Uncertainty Principle. We
show how the difference in the sign of the fundamental Poisson bracket is
reflected in a sign of the modified source term in the Friedmann equation,
responsible for the removal of the initial singularity in the polymer case and
for the survival of a singular point in the Universe past, when the Generalized
Uncertainty Principle is concerned.
Then, we study the regularization of the vacuum energy of a free massless
scalar field, by implementing a second quantization formalism in the context of
Polymer Quantum Mechanics. We show that, from this reformulation, naturally
emerges a Cosmological Constant term for the isotropic Universe, whose value
depends directly on the polymer parameter of the regularization.
Finally, we investigate the behaviour of gravitational waves on the
background of a modified dynamics, according to the semiclassical Friedmann
equation. We demonstrate that the presence of a Bounce in the Universe past,
naturally removes the divergence of the gravitational wave amplitude and they
can, in principle, propagate across the minimum volume turning point. This
result offers the intriguing perspective for the detection of gravitational
signals coming from the pre-Big Bounce collapsing Universe.
| [
{
"created": "Wed, 6 Feb 2019 11:57:23 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Apr 2020 10:53:21 GMT",
"version": "v2"
}
] | 2020-04-17 | [
[
"Barca",
"Gabriele",
""
],
[
"Di Antonio",
"Paolo",
""
],
[
"Montani",
"Giovanni",
""
],
[
"Patti",
"Alberto",
""
]
] | We analyze some relevant semiclassical and quantum features of the implementation of Polymer Quantum Mechanics to the phenomenology of the flat isotropic Universe. We firstly investigate a parallelism between the semiclassical polymer dynamics of the flat isotropic Universe, as reduced to the effect of a modified simplectic structure, and the so-called Generalized Uncertainty Principle. We show how the difference in the sign of the fundamental Poisson bracket is reflected in a sign of the modified source term in the Friedmann equation, responsible for the removal of the initial singularity in the polymer case and for the survival of a singular point in the Universe past, when the Generalized Uncertainty Principle is concerned. Then, we study the regularization of the vacuum energy of a free massless scalar field, by implementing a second quantization formalism in the context of Polymer Quantum Mechanics. We show that, from this reformulation, naturally emerges a Cosmological Constant term for the isotropic Universe, whose value depends directly on the polymer parameter of the regularization. Finally, we investigate the behaviour of gravitational waves on the background of a modified dynamics, according to the semiclassical Friedmann equation. We demonstrate that the presence of a Bounce in the Universe past, naturally removes the divergence of the gravitational wave amplitude and they can, in principle, propagate across the minimum volume turning point. This result offers the intriguing perspective for the detection of gravitational signals coming from the pre-Big Bounce collapsing Universe. |
1809.03320 | Mustapha Azreg-A\"inou | Mustapha Azreg-A\"inou, Ayyesha K. Ahmed, Mubasher Jamil | Spherical accretion by normal and phantom Einstein--Maxwell--dilaton
black holes | 18 pages, 2 figures, minor corrections, references added | Class. Quantum Grav. 35 (2018) 235001 | 10.1088/1361-6382/aae997 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the spherical accretion process for general static spherically
symmetric fluids. We analyze this process by using the general metric ansatz
for spherically symmetric black holes. We specialize to the case of normal and
phantom isothermal fluids and investigate their accretion process onto normal
and phantom Einstein-Maxwell-dilaton black holes. Backreaction effects are
discussed.
| [
{
"created": "Wed, 5 Sep 2018 04:27:10 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Nov 2018 06:40:32 GMT",
"version": "v2"
}
] | 2018-11-07 | [
[
"Azreg-Aïnou",
"Mustapha",
""
],
[
"Ahmed",
"Ayyesha K.",
""
],
[
"Jamil",
"Mubasher",
""
]
] | We investigate the spherical accretion process for general static spherically symmetric fluids. We analyze this process by using the general metric ansatz for spherically symmetric black holes. We specialize to the case of normal and phantom isothermal fluids and investigate their accretion process onto normal and phantom Einstein-Maxwell-dilaton black holes. Backreaction effects are discussed. |
2110.08560 | Gamal G.L. Nashed | G.G.L. Nashed and Shin'ichi Nojiri | Black holes with Lagrange multiplier and potential in mimetic-like
gravitational theory: multi-horizon black holes | 14 pages, 12 figures. arXiv admin note: text overlap with
arXiv:2107.13550 | JCAP05(2022)011 | 10.1088/1475-7516/2022/05/011 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this paper, we employ the {\bf mimetic-like} field equations coupled with
the Lagrange multiplier and %mimetic {\bf potential} to derive non-trivial
spherically symmetric black hole (BH) solutions. We divided this study into
three cases: The first one in which we take the Lagrange multiplier and
%mimetic {\bf the potential} to have vanishing value and derive a BH solution
that completely coincides with the BH of the Einstein general relativity
despite the non-vanishing value of the {\bf mimetic-like scalar field}. The
first case is completely consistent with the previous studies in the literature
that mimetic theory coincides with GR \cite{Nashed:2018qag}. In the second
case, we derive a solution with a constant value of the {\bf potential} and a
dynamical value of the Lagrange multiplier. This solution has no horizon and
therefore the obtained spacetime does not correspond to the BH. In this
solution, there appears the region of the Euclidian signature where the
signature of the diagonal components of the metric is $(+,+,+,+)$ or the region
with two times where the signature is $(+,+,-,-)$. Finally, we derive a BH
solution with non-vanishing values of the Lagrange multiplier, {\bf potential},
and {\bf mimetic-like scalar field}. This BH shows a soft singularity compared
with the Einstein BH solution. The relevant physics of the third case is
discussed by showing their behavior of the metric potential at infinity,
calculating their energy conditions, and study their thermodynamical
quantities. We give a brief discussion on how our third case can generate a BH
with three horizons as in the de Sitter-Reissner-Nordstr\"om black hole
spacetime, where the largest horizon is the cosmological one and two correspond
to the outer and inner horizons of the BH. Even in the third case, there
appears the region of the Euclidian signature or the region with two times.
| [
{
"created": "Sat, 16 Oct 2021 12:04:46 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Oct 2021 06:56:41 GMT",
"version": "v2"
},
{
"created": "Tue, 7 Dec 2021 18:13:02 GMT",
"version": "v3"
},
{
"created": "Thu, 9 Dec 2021 08:39:19 GMT",
"version": "v4"
},
{
"cre... | 2022-05-18 | [
[
"Nashed",
"G. G. L.",
""
],
[
"Nojiri",
"Shin'ichi",
""
]
] | In this paper, we employ the {\bf mimetic-like} field equations coupled with the Lagrange multiplier and %mimetic {\bf potential} to derive non-trivial spherically symmetric black hole (BH) solutions. We divided this study into three cases: The first one in which we take the Lagrange multiplier and %mimetic {\bf the potential} to have vanishing value and derive a BH solution that completely coincides with the BH of the Einstein general relativity despite the non-vanishing value of the {\bf mimetic-like scalar field}. The first case is completely consistent with the previous studies in the literature that mimetic theory coincides with GR \cite{Nashed:2018qag}. In the second case, we derive a solution with a constant value of the {\bf potential} and a dynamical value of the Lagrange multiplier. This solution has no horizon and therefore the obtained spacetime does not correspond to the BH. In this solution, there appears the region of the Euclidian signature where the signature of the diagonal components of the metric is $(+,+,+,+)$ or the region with two times where the signature is $(+,+,-,-)$. Finally, we derive a BH solution with non-vanishing values of the Lagrange multiplier, {\bf potential}, and {\bf mimetic-like scalar field}. This BH shows a soft singularity compared with the Einstein BH solution. The relevant physics of the third case is discussed by showing their behavior of the metric potential at infinity, calculating their energy conditions, and study their thermodynamical quantities. We give a brief discussion on how our third case can generate a BH with three horizons as in the de Sitter-Reissner-Nordstr\"om black hole spacetime, where the largest horizon is the cosmological one and two correspond to the outer and inner horizons of the BH. Even in the third case, there appears the region of the Euclidian signature or the region with two times. |
2107.13804 | Tact Ikeda | Tact Ikeda, Aya Iyonaga and Tsutomu Kobayashi | Stars disformally coupled to a shift-symmetric scalar field | 12 pages, 4 figures | null | 10.1103/PhysRevD.104.104009 | RUP-21-13 | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We investigate static and spherically symmetric stars disformally coupled to
a scalar field. The scalar field is assumed to be shift symmetric, and hence
the conformal and disformal factors of the metric coupled to matter are
dependent only on the kinetic term of the scalar field. Assuming that the
scalar field is linearly dependent on time, we consider a general
shift-symmetric scalar-tensor theory and a general form of the matter
energy-momentum tensor that allows for the anisotropic pressure and the heat
flux in the radial direction. This is a natural starting point in light of how
the gravitational field equations and the energy-momentum tensor transform
under a disformal transformation. By inspecting the structure of the
hydrostatic equilibrium equation in the presence of the derivative-dependent
conformal and disformal factors, we show that the energy density and tangential
pressure must vanish at the surface of a star. This fact is used to prove the
disformal invariance of the surface of a star, which was previously subtle and
unclear. We then focus on the shift-symmetric k-essence disformally coupled to
matter, and study the interior and exterior metric functions and scalar-field
profile in more detail. It is found that there are two branches of the solution
depending on the velocity of the scalar field. The disformally-related metric
functions of the exterior spacetime are also discussed.
| [
{
"created": "Thu, 29 Jul 2021 08:07:35 GMT",
"version": "v1"
}
] | 2021-11-17 | [
[
"Ikeda",
"Tact",
""
],
[
"Iyonaga",
"Aya",
""
],
[
"Kobayashi",
"Tsutomu",
""
]
] | We investigate static and spherically symmetric stars disformally coupled to a scalar field. The scalar field is assumed to be shift symmetric, and hence the conformal and disformal factors of the metric coupled to matter are dependent only on the kinetic term of the scalar field. Assuming that the scalar field is linearly dependent on time, we consider a general shift-symmetric scalar-tensor theory and a general form of the matter energy-momentum tensor that allows for the anisotropic pressure and the heat flux in the radial direction. This is a natural starting point in light of how the gravitational field equations and the energy-momentum tensor transform under a disformal transformation. By inspecting the structure of the hydrostatic equilibrium equation in the presence of the derivative-dependent conformal and disformal factors, we show that the energy density and tangential pressure must vanish at the surface of a star. This fact is used to prove the disformal invariance of the surface of a star, which was previously subtle and unclear. We then focus on the shift-symmetric k-essence disformally coupled to matter, and study the interior and exterior metric functions and scalar-field profile in more detail. It is found that there are two branches of the solution depending on the velocity of the scalar field. The disformally-related metric functions of the exterior spacetime are also discussed. |
1412.7632 | Anirban Saha Dr. | Sunandan Gangopadhyay, Anirban Saha, Swarup Saha | Interaction of a circularly polarised gravitational wave with a charged
particle in a static magnetic background | 8 pages, Latex | Gen.Rel.Grav. 47 (2015) 6, 65 | 10.1007/s10714-015-1906-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Interaction of a charged particle in a static magnetic background, i.e., a
Landau system with circularly polarised gravitational wave (GW) is studied
quantum mechanically in the long wavelength and low velocity limit. We quantize
the classical Hamiltonian following \cite{speli}. The rotating polarization
vectors of the circularly polarized GW are employed to form a unique
directional triad which served as the coordinate axes. The Schrodinger
equations for the system are cast in the form of a set of coupled linear
differential equations. This system is solved by iterative technique. We
compute the time-evolution of the position and momentum expectation values of
the particle. The results show that the resonance behaviour obtained
earlier\cite{emgw_classical} by classical treatements of the system has a
quantum analogue not only for the linearly polarized GW \cite{emgw_1_lin}, but
for circularly polarized GW as well.
| [
{
"created": "Wed, 24 Dec 2014 09:51:49 GMT",
"version": "v1"
}
] | 2015-06-03 | [
[
"Gangopadhyay",
"Sunandan",
""
],
[
"Saha",
"Anirban",
""
],
[
"Saha",
"Swarup",
""
]
] | Interaction of a charged particle in a static magnetic background, i.e., a Landau system with circularly polarised gravitational wave (GW) is studied quantum mechanically in the long wavelength and low velocity limit. We quantize the classical Hamiltonian following \cite{speli}. The rotating polarization vectors of the circularly polarized GW are employed to form a unique directional triad which served as the coordinate axes. The Schrodinger equations for the system are cast in the form of a set of coupled linear differential equations. This system is solved by iterative technique. We compute the time-evolution of the position and momentum expectation values of the particle. The results show that the resonance behaviour obtained earlier\cite{emgw_classical} by classical treatements of the system has a quantum analogue not only for the linearly polarized GW \cite{emgw_1_lin}, but for circularly polarized GW as well. |
2203.15141 | John Klauder | John R. Klauder | A Straight Forward Path to a Path Integration of Einstein's Gravity | 19 pages, a review of path integration that leads to a path integral
for gravity, a few tiny improvements, minor modifications, corrected O and
partial TeX definitions, a sign error has \ nu \rightarrow 0 TO
\nu\rightarrtow. inviity | null | 10.1016/j.aop.2022.169148 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Path integration is a respected form of quantization that all theoretical
quantum physicists should welcome. This elaboration begins with simple examples
of three different versions of path integration. After an important
clarification of how gravity can be properly quantized, an appropriate path
integral, that also incorporates necessary constraint issues, becomes a proper
path integral for gravity that can effectively be obtained. How to evaluate
such path integrals is another aspect, but most likely best done by
computational efforts including Monte Carlo-like procedures.
| [
{
"created": "Mon, 28 Mar 2022 23:26:55 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Mar 2022 14:36:10 GMT",
"version": "v2"
},
{
"created": "Mon, 11 Apr 2022 19:17:13 GMT",
"version": "v3"
},
{
"created": "Mon, 16 May 2022 23:47:25 GMT",
"version": "v4"
},
{
"c... | 2023-01-10 | [
[
"Klauder",
"John R.",
""
]
] | Path integration is a respected form of quantization that all theoretical quantum physicists should welcome. This elaboration begins with simple examples of three different versions of path integration. After an important clarification of how gravity can be properly quantized, an appropriate path integral, that also incorporates necessary constraint issues, becomes a proper path integral for gravity that can effectively be obtained. How to evaluate such path integrals is another aspect, but most likely best done by computational efforts including Monte Carlo-like procedures. |
0912.2858 | Rolando Gaitan Deveras RGD | Rolando Gaitan D. (Grupo de F\'isica Te\'orica, Departamento de
F\'isica, FACYT-UC), Juan Petit and Alfredo Mej\'ia | Variational principle and free falling in a space-time with torsion | Talk given at the VII Congress of the Venezuelan Physical Society,
Caracas, December 07-11 of 2009 | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A comparison between the two possible variational principles for the study of
a free falling spinless particle in a space-time with torsion is noted. It is
well known that the autoparallel trajectories can be obtained from a
variational principle based on a non-holonomic mapping, starting with the
standard world-line action. In a contrast, we explore a world-line action with
a modified metric, thinking about the old idea of contorsion (torsion)
potentials. A fixed-ends variational principle can reproduce autoparallel
trajectories without restrictions on space-time torsion. As an illustration we
have considered a perturbative Weitzenb$\ddot{o}$ck space-time. The
non-perturbative problem is stablished at the end.
| [
{
"created": "Tue, 15 Dec 2009 12:10:04 GMT",
"version": "v1"
}
] | 2009-12-21 | [
[
"D.",
"Rolando Gaitan",
"",
"Grupo de Física Teórica, Departamento de\n Física, FACYT-UC"
],
[
"Petit",
"Juan",
""
],
[
"Mejía",
"Alfredo",
""
]
] | A comparison between the two possible variational principles for the study of a free falling spinless particle in a space-time with torsion is noted. It is well known that the autoparallel trajectories can be obtained from a variational principle based on a non-holonomic mapping, starting with the standard world-line action. In a contrast, we explore a world-line action with a modified metric, thinking about the old idea of contorsion (torsion) potentials. A fixed-ends variational principle can reproduce autoparallel trajectories without restrictions on space-time torsion. As an illustration we have considered a perturbative Weitzenb$\ddot{o}$ck space-time. The non-perturbative problem is stablished at the end. |
0712.1273 | Lorenzo Iorio | Lorenzo Iorio | Jupiter, Saturn and the Pioneer anomaly: a planetary-based independent
test | Latex, 6 pages, no figures, no tables, 22 references. To appear in
JGP (Journal of Gravitational Physics) | Journal of Gravitational Physics, vol. 1, no.1, pp. 5-8, 2007 | null | null | gr-qc astro-ph hep-ph physics.space-ph | null | In this paper we use the ratio of the corrections to the standard
Newtonian/Einsteinian secular precessions of the longitudes of perihelia of
Jupiter and Saturn, recently estimated by the Russian astronomer E.V. Pitjeva
by fitting almost one century of data with the EPM ephemerides, to make an
independent, planetary-based test of the hypothesis that the Pioneer anomaly
(PA), as it is presently known in the 5-10 AU region, is of gravitational
origin. Accounting for the errors in the determined apsidal extra-rates and in
the values of the PA acceleration at the orbits of Jupiter and Saturn the
answer is negative. If and when the re-analysis of the entire Pioneer 10/11
will be completed more firm conclusions could be reached. Moreover, it would
also be important that other teams of astronomers estimate independently their
own corrections to the perihelion precessions.
| [
{
"created": "Sat, 8 Dec 2007 10:31:43 GMT",
"version": "v1"
}
] | 2007-12-15 | [
[
"Iorio",
"Lorenzo",
""
]
] | In this paper we use the ratio of the corrections to the standard Newtonian/Einsteinian secular precessions of the longitudes of perihelia of Jupiter and Saturn, recently estimated by the Russian astronomer E.V. Pitjeva by fitting almost one century of data with the EPM ephemerides, to make an independent, planetary-based test of the hypothesis that the Pioneer anomaly (PA), as it is presently known in the 5-10 AU region, is of gravitational origin. Accounting for the errors in the determined apsidal extra-rates and in the values of the PA acceleration at the orbits of Jupiter and Saturn the answer is negative. If and when the re-analysis of the entire Pioneer 10/11 will be completed more firm conclusions could be reached. Moreover, it would also be important that other teams of astronomers estimate independently their own corrections to the perihelion precessions. |
gr-qc/0308012 | Rituparno Goswami | Pankaj S. Joshi, Rituparno Goswami, Naresh Dadhich | The critical role of shear in gravitational collapse | 4 pages, Letter, Revised version,clarity improved | null | null | null | gr-qc | null | We investigate here how the shearing effects present within a collapsing
matter cloud influence the outcome of gravitational collapse in terms of
formation of either a black hole or a naked singularity as the final end state.
For collapse of practically all physically reasonable matter fields, we prove
that it would always end up in a black hole if it is either shear-free or has
homogeneous density. Thus it follows that whenever a naked singularity forms as
end product, the collapsing cloud must necessarily be shearing with
inhomogeneous density. Our consideration brings out the physical forces at work
which could cause a naked singularity to result as collapse end state, rather
than a black hole.
| [
{
"created": "Wed, 6 Aug 2003 00:15:32 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Aug 2003 22:24:31 GMT",
"version": "v2"
},
{
"created": "Tue, 13 Jan 2004 05:15:07 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Joshi",
"Pankaj S.",
""
],
[
"Goswami",
"Rituparno",
""
],
[
"Dadhich",
"Naresh",
""
]
] | We investigate here how the shearing effects present within a collapsing matter cloud influence the outcome of gravitational collapse in terms of formation of either a black hole or a naked singularity as the final end state. For collapse of practically all physically reasonable matter fields, we prove that it would always end up in a black hole if it is either shear-free or has homogeneous density. Thus it follows that whenever a naked singularity forms as end product, the collapsing cloud must necessarily be shearing with inhomogeneous density. Our consideration brings out the physical forces at work which could cause a naked singularity to result as collapse end state, rather than a black hole. |
1507.05587 | Daniele Trifir\'o | Daniele Trifir\`o (1 and 2), Richard O'Shaughnessy (3), Davide Gerosa
(4), Emanuele Berti (2 and 5), Michael Kesden (6), Tyson Littenberg (7),
Ulrich Sperhake (4, 2 and 8) ((1) Dipartimento di Fisica E. Fermi,
Universit\`a di Pisa, Italy, (2) Department of Physics and Astronomy, The
University of Mississippi, USA, (3) Center for Computational Relativity and
Gravitation, Rochester Institute of Technology, Rochester, NY, USA, (4)
Department of Applied Mathematics and Theoretical Physics, Centre for
Mathematical Sciences, University of Cambridge, Cambridge, UK, (5) CENTRA,
Departamento de F\'isica, Instituto Superior T\'ecnico, Universidade de
Lisboa, Lisboa, Portugal, (6) Department of Physics, The University of Texas
at Dallas, Richardson, TX, USA, (7) Center for Interdisciplinary Exploration
and Research in Astrophysics (CIERA) and Department of Physics and Astronomy,
Northwestern University, Evanston, IL, USA, (8) California Institute of
Technology, Pasadena, CA, USA) | Distinguishing black-hole spin-orbit resonances by their gravitational
wave signatures. II: Full parameter estimation | 24 pages, 14 figures | Phys. Rev. D 93, 044071 (2016) | 10.1103/PhysRevD.93.044071 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waves from coalescing binary black holes encode the evolution
of their spins prior to merger. In the post-Newtonian regime and on the
precession timescale, this evolution has one of three morphologies, with the
spins either librating around one of two fixed points ("resonances") or
circulating freely. In this work we perform full parameter estimation on
resonant binaries with fixed masses and spin magnitudes, changing three
parameters: a conserved "projected effective spin" $\xi$ and resonant family
$\Delta\Phi=0,\pi$ (which uniquely label the source), the inclination
$\theta_{JN}$ of the binary's total angular momentum with respect to the line
of sight (which determines the strength of precessional effects in the
waveform), and the signal amplitude. We demonstrate that resonances can be
distinguished for a wide range of binaries, except for highly symmetric
configurations where precessional effects are suppressed. Motivated by new
insight into double-spin evolution, we introduce new variables to characterize
precessing black hole binaries which naturally reflects the timescale
separation of the system and therefore better encode the dynamical information
carried by gravitational waves.
| [
{
"created": "Mon, 20 Jul 2015 18:41:33 GMT",
"version": "v1"
},
{
"created": "Sat, 12 Dec 2015 21:17:54 GMT",
"version": "v2"
},
{
"created": "Mon, 15 Feb 2016 10:41:48 GMT",
"version": "v3"
}
] | 2016-03-02 | [
[
"Trifirò",
"Daniele",
"",
"1 and 2"
],
[
"O'Shaughnessy",
"Richard",
"",
"2 and 5"
],
[
"Gerosa",
"Davide",
"",
"2 and 5"
],
[
"Berti",
"Emanuele",
"",
"2 and 5"
],
[
"Kesden",
"Michael",
"",
"4, 2 and 8"
],
[
... | Gravitational waves from coalescing binary black holes encode the evolution of their spins prior to merger. In the post-Newtonian regime and on the precession timescale, this evolution has one of three morphologies, with the spins either librating around one of two fixed points ("resonances") or circulating freely. In this work we perform full parameter estimation on resonant binaries with fixed masses and spin magnitudes, changing three parameters: a conserved "projected effective spin" $\xi$ and resonant family $\Delta\Phi=0,\pi$ (which uniquely label the source), the inclination $\theta_{JN}$ of the binary's total angular momentum with respect to the line of sight (which determines the strength of precessional effects in the waveform), and the signal amplitude. We demonstrate that resonances can be distinguished for a wide range of binaries, except for highly symmetric configurations where precessional effects are suppressed. Motivated by new insight into double-spin evolution, we introduce new variables to characterize precessing black hole binaries which naturally reflects the timescale separation of the system and therefore better encode the dynamical information carried by gravitational waves. |
gr-qc/9703011 | Alexander L. Gromov | G.N.Parfionov, R.R.Zapatrine | Empirical topology in the histories approach to quantum theory | 17 pages, latex, some technical corrections | null | null | IRB-MSP-970301 | gr-qc quant-ph | null | An idealized experiment estimating the spacetime topology is considered in
both classical and quantum frameworks. The latter is described in terms of
histories approach to quantum theory. A procedure creating combinatorial models
of topology is suggested. The correspondence between these models and
discretized spacetime models is established.
| [
{
"created": "Wed, 5 Mar 1997 07:53:34 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Mar 1997 07:02:12 GMT",
"version": "v2"
}
] | 2008-02-03 | [
[
"Parfionov",
"G. N.",
""
],
[
"Zapatrine",
"R. R.",
""
]
] | An idealized experiment estimating the spacetime topology is considered in both classical and quantum frameworks. The latter is described in terms of histories approach to quantum theory. A procedure creating combinatorial models of topology is suggested. The correspondence between these models and discretized spacetime models is established. |
1411.5672 | Philipp Hoehn | Philipp A. Hoehn | Canonical linearized Regge Calculus: counting lattice gravitons with
Pachner moves | 26+13 pages, 2 appendices, many figures. References updated, small
clarifications added. This article is fairly self-contained | Phys. Rev. D 91, 124034 (2015) | 10.1103/PhysRevD.91.124034 | null | gr-qc hep-lat math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We afford a systematic and comprehensive account of the canonical dynamics of
4D Regge Calculus perturbatively expanded to linear order around a flat
background. To this end, we consider the Pachner moves which generate the most
basic and general simplicial evolution scheme. The linearized regime features a
vertex displacement (`diffeomorphism') symmetry for which we derive an abelian
constraint algebra. This permits to identify gauge invariant `lattice
gravitons' as propagating curvature degrees of freedom. The Pachner moves admit
a simple method to explicitly count the gauge and `graviton' degrees of freedom
on an evolving triangulated hypersurface and we clarify the distinct role of
each move in the dynamics. It is shown that the 1-4 move generates four `lapse
and shift' variables and four conjugate vertex displacement generators; the 2-3
move generates a `graviton'; the 3-2 move removes one `graviton' and produces
the only non-trivial equation of motion; and the 4-1 move removes four `lapse
and shift' variables and trivializes the four conjugate symmetry generators. It
is further shown that the Pachner moves preserve the vertex displacement
generators. These results may provide new impetus for exploring `graviton
dynamics' in discrete quantum gravity models.
| [
{
"created": "Thu, 20 Nov 2014 20:55:05 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Nov 2014 15:34:43 GMT",
"version": "v2"
}
] | 2015-06-17 | [
[
"Hoehn",
"Philipp A.",
""
]
] | We afford a systematic and comprehensive account of the canonical dynamics of 4D Regge Calculus perturbatively expanded to linear order around a flat background. To this end, we consider the Pachner moves which generate the most basic and general simplicial evolution scheme. The linearized regime features a vertex displacement (`diffeomorphism') symmetry for which we derive an abelian constraint algebra. This permits to identify gauge invariant `lattice gravitons' as propagating curvature degrees of freedom. The Pachner moves admit a simple method to explicitly count the gauge and `graviton' degrees of freedom on an evolving triangulated hypersurface and we clarify the distinct role of each move in the dynamics. It is shown that the 1-4 move generates four `lapse and shift' variables and four conjugate vertex displacement generators; the 2-3 move generates a `graviton'; the 3-2 move removes one `graviton' and produces the only non-trivial equation of motion; and the 4-1 move removes four `lapse and shift' variables and trivializes the four conjugate symmetry generators. It is further shown that the Pachner moves preserve the vertex displacement generators. These results may provide new impetus for exploring `graviton dynamics' in discrete quantum gravity models. |
1910.13522 | Merav Hadad | Merav Hadad | Truncation of Einstein equations through Gravitational Foliation | 26 pages, no figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In previous works, we suggested considering a (3+1)D quantum gravitational
field as an evolution of a (2+1)D renormalized quantum gravitational field
along the direction of the gravitational force. The starting point of the
suggestion is a derivation of a unique hypersurface which looks effectively
like (2+1)D from the point of view of Einstein equations in (3+1)D. In this
paper, we derive such unique hypersurfaces for different kinds of stationary
spherical metrics. We find that these hypersurfaces exist whenever all the
components of the gravitational force field vanish on the hypersurface. We
discuss the implication of this result and the necessary further work.
| [
{
"created": "Tue, 29 Oct 2019 20:42:06 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Feb 2021 13:29:29 GMT",
"version": "v2"
},
{
"created": "Fri, 15 Jul 2022 10:31:54 GMT",
"version": "v3"
}
] | 2022-07-18 | [
[
"Hadad",
"Merav",
""
]
] | In previous works, we suggested considering a (3+1)D quantum gravitational field as an evolution of a (2+1)D renormalized quantum gravitational field along the direction of the gravitational force. The starting point of the suggestion is a derivation of a unique hypersurface which looks effectively like (2+1)D from the point of view of Einstein equations in (3+1)D. In this paper, we derive such unique hypersurfaces for different kinds of stationary spherical metrics. We find that these hypersurfaces exist whenever all the components of the gravitational force field vanish on the hypersurface. We discuss the implication of this result and the necessary further work. |
1406.5919 | Ettore Minguzzi | E. Minguzzi | Area theorem and smoothness of compact Cauchy horizons | 44 pages. v2: added Sect. 2.4 on the propagation of singularities and
a second version of the area theorem (Theor. 14) which quantifies the area
increase due to the jump set | Commun. Math. Phys. 339, 57-98 (2015) | 10.1007/s00220-015-2415-8 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain an improved version of the area theorem for not necessarily
differentiable horizons which, in conjunction with a recent result on the
completeness of generators, allows us to prove that under the null energy
condition every compactly generated Cauchy horizon is smooth and compact. We
explore the consequences of this result for time machines, topology change,
black holes and cosmic censorship. For instance, it is shown that compact
Cauchy horizons cannot form in a non-empty spacetime which satisfies the stable
dominant energy condition wherever there is some source content.
| [
{
"created": "Mon, 23 Jun 2014 14:24:34 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Jun 2015 13:06:06 GMT",
"version": "v2"
}
] | 2015-07-28 | [
[
"Minguzzi",
"E.",
""
]
] | We obtain an improved version of the area theorem for not necessarily differentiable horizons which, in conjunction with a recent result on the completeness of generators, allows us to prove that under the null energy condition every compactly generated Cauchy horizon is smooth and compact. We explore the consequences of this result for time machines, topology change, black holes and cosmic censorship. For instance, it is shown that compact Cauchy horizons cannot form in a non-empty spacetime which satisfies the stable dominant energy condition wherever there is some source content. |
1007.4337 | Yuri Obukhov | Natalia Kudryashova and Yuri N. Obukhov | On the dynamics of classical particle with spin | 14 pages, Revtex, no figures | Phys.Lett.A374:3801-3805,2010 | 10.1016/j.physleta.2010.07.046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The complete explicitly covariant 4-dimensional description of the dynamics
of a free classical particle with spin within the framework of the special
relativity theory is presented. The key point of our approach is the the
introduction of the new vector field which enables to define the analogues of
the mean spin and position variables. The supplementary conditions are
discussed and it is demonstrated that the Frenkel condition unambiguously
determines the dynamics of a spinning particle.
| [
{
"created": "Sun, 25 Jul 2010 17:39:18 GMT",
"version": "v1"
}
] | 2014-11-21 | [
[
"Kudryashova",
"Natalia",
""
],
[
"Obukhov",
"Yuri N.",
""
]
] | The complete explicitly covariant 4-dimensional description of the dynamics of a free classical particle with spin within the framework of the special relativity theory is presented. The key point of our approach is the the introduction of the new vector field which enables to define the analogues of the mean spin and position variables. The supplementary conditions are discussed and it is demonstrated that the Frenkel condition unambiguously determines the dynamics of a spinning particle. |
gr-qc/0207080 | Badri Krishnan | Abhay Ashtekar and Badri Krishnan | Dynamical Horizons: Energy, Angular Momentum, Fluxes and Balance Laws | 4 pages, RevTeX4. Minor typos corrected. To appear in Phys.Rev.Lett | Phys.Rev.Lett.89:261101,2002 | 10.1103/PhysRevLett.89.261101 | null | gr-qc | null | Dynamical horizons are considered in full, non-linear general relativity.
Expressions of fluxes of energy and angular momentum carried by gravitational
waves across these horizons are obtained. Fluxes are local, the energy flux is
positive and change in the horizon area is related to these fluxes. The flux
formulae also give rise to balance laws analogous to the ones obtained by Bondi
and Sachs at null infinity and provide generalizations of the first and second
laws of black hole mechanics.
| [
{
"created": "Sun, 21 Jul 2002 19:12:27 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jul 2002 19:09:41 GMT",
"version": "v2"
},
{
"created": "Sun, 3 Nov 2002 19:57:59 GMT",
"version": "v3"
}
] | 2011-05-05 | [
[
"Ashtekar",
"Abhay",
""
],
[
"Krishnan",
"Badri",
""
]
] | Dynamical horizons are considered in full, non-linear general relativity. Expressions of fluxes of energy and angular momentum carried by gravitational waves across these horizons are obtained. Fluxes are local, the energy flux is positive and change in the horizon area is related to these fluxes. The flux formulae also give rise to balance laws analogous to the ones obtained by Bondi and Sachs at null infinity and provide generalizations of the first and second laws of black hole mechanics. |
2010.03708 | Yao-Zhong Zhang | Yao-Zhong Zhang | Analytic solutions of the Teukolsky equation for massless perturbations
of any spin in de Sitter background | LaTex 12 pages. To appear in J. Math. Phys | J. Math. Phys. 61, 103508 (2020) | 10.1063/5.0015848 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present analytic solutions to the Teukolsky equation for massless
perturbations of any spin in the 4-dimensional de Sitter background. The
angular part of the equation fixes the separation constant to a discrete set
and its solution is given by hypergeometric polynomials. For the radial part,
we derive analytic power series solution which is regular at the poles and
determine a transcendental function whose zeros give the characteristic values
of the wave frequency. We study the existence of explicit polynomial solutions
to the radial equation and obtain two classes of singular closed-form
solutions, one with discrete wave frequencies and the other with continuous
frequency spectra.
| [
{
"created": "Thu, 8 Oct 2020 00:45:27 GMT",
"version": "v1"
}
] | 2020-10-21 | [
[
"Zhang",
"Yao-Zhong",
""
]
] | We present analytic solutions to the Teukolsky equation for massless perturbations of any spin in the 4-dimensional de Sitter background. The angular part of the equation fixes the separation constant to a discrete set and its solution is given by hypergeometric polynomials. For the radial part, we derive analytic power series solution which is regular at the poles and determine a transcendental function whose zeros give the characteristic values of the wave frequency. We study the existence of explicit polynomial solutions to the radial equation and obtain two classes of singular closed-form solutions, one with discrete wave frequencies and the other with continuous frequency spectra. |
gr-qc/9703061 | Max Banados | M. Banados, M. Henneaux, C. Iannuzzo and C.M. Viallet | A note on the gauge symmetries of pure Chern-Simons theories with p-form
gauge fields | 22 pages, latex, one eps figure | Class.Quant.Grav. 14 (1997) 2455-2468 | 10.1088/0264-9381/14/9/006 | ULB-TH-97/04, PAR-LPTHE-97-08 | gr-qc hep-th | null | The gauge symmetries of pure Chern-Simons theories with p-form gauge fields
are analyzed. It is shown that the number of independent gauge symmetries
depends crucially on the parity of p. The case where p is odd appears to be a
direct generalization of the p=1 case and presents the remarkable feature that
the timelike diffeomorphisms can be expressed in terms of the spatial
diffeomorphisms and the internal gauge symmetries. By constrast, the timelike
diffeomorphisms may be an independent gauge symmetry when p is even. This
happens when the number of fields and the spacetime dimension fulfills an
algebraic condition which is explicitely written.
| [
{
"created": "Fri, 21 Mar 1997 14:56:26 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Banados",
"M.",
""
],
[
"Henneaux",
"M.",
""
],
[
"Iannuzzo",
"C.",
""
],
[
"Viallet",
"C. M.",
""
]
] | The gauge symmetries of pure Chern-Simons theories with p-form gauge fields are analyzed. It is shown that the number of independent gauge symmetries depends crucially on the parity of p. The case where p is odd appears to be a direct generalization of the p=1 case and presents the remarkable feature that the timelike diffeomorphisms can be expressed in terms of the spatial diffeomorphisms and the internal gauge symmetries. By constrast, the timelike diffeomorphisms may be an independent gauge symmetry when p is even. This happens when the number of fields and the spacetime dimension fulfills an algebraic condition which is explicitely written. |
1610.06637 | Tommi Markkanen | Tommi Markkanen | Decoherence Can Relax Cosmic Acceleration: an Example | 11 pages, 2 figures. v2: expanded text, new title and abstract.
Results unchanged. v3: version accepted for publication by JCAP, added
references | null | 10.1088/1475-7516/2017/09/022 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate back reaction in de Sitter space in an approach where only
states that are observationally accessible are included in the density matrix.
Using the Bunch-Davies vacuum as the initial condition we find for a conformal
scalar field and a cosmological constant that tracing over the unobservable
states beyond the cosmological horizon leads to a thermal spectrum of particles
and that such a configuration is unstable under semi-classical back reaction.
It is concluded that this prescription results in an instability of de Sitter
space with a gradually increasing horizon size.
| [
{
"created": "Fri, 21 Oct 2016 00:54:49 GMT",
"version": "v1"
},
{
"created": "Thu, 24 Aug 2017 12:47:35 GMT",
"version": "v2"
},
{
"created": "Fri, 8 Sep 2017 17:00:36 GMT",
"version": "v3"
}
] | 2017-09-20 | [
[
"Markkanen",
"Tommi",
""
]
] | We investigate back reaction in de Sitter space in an approach where only states that are observationally accessible are included in the density matrix. Using the Bunch-Davies vacuum as the initial condition we find for a conformal scalar field and a cosmological constant that tracing over the unobservable states beyond the cosmological horizon leads to a thermal spectrum of particles and that such a configuration is unstable under semi-classical back reaction. It is concluded that this prescription results in an instability of de Sitter space with a gradually increasing horizon size. |
2306.09289 | Alexey Golovnev | Daniel Blixt, Alexey Golovnev, Maria-Jose Guzman, Ramazan Maksyutov | Geometry and covariance of symmetric teleparallel theories of gravity | minor amendments; 19 pages | Physical Review D 109 (2024) 044061 | 10.1103/PhysRevD.109.044061 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the geometric foundations and derivations of equations of motion
for symmetric teleparallel theories of gravity in the coincident gauge and
covariant frameworks. We discuss the theoretical challenges introduced by the
auxiliary fields responsible for the covariantisation procedure. We elucidate a
tetradic structure interpretation behind this covariant formulation. Regarding
the effect of covariantisation at the level of the equations of motion, we
explicitly show that the only physical change, in case of setting an arbitrary
energy-momentum tensor to the right hand side, resides in the requirement of
the fulfillment of the covariant conservation laws. Also, we have explicitly
introduced the fundamental covariantly-conserved teleparallel tetrad for the
symmetric teleparallel frameworks.
| [
{
"created": "Thu, 15 Jun 2023 17:15:55 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Oct 2023 05:23:38 GMT",
"version": "v2"
},
{
"created": "Fri, 2 Feb 2024 16:54:23 GMT",
"version": "v3"
}
] | 2024-02-27 | [
[
"Blixt",
"Daniel",
""
],
[
"Golovnev",
"Alexey",
""
],
[
"Guzman",
"Maria-Jose",
""
],
[
"Maksyutov",
"Ramazan",
""
]
] | We present the geometric foundations and derivations of equations of motion for symmetric teleparallel theories of gravity in the coincident gauge and covariant frameworks. We discuss the theoretical challenges introduced by the auxiliary fields responsible for the covariantisation procedure. We elucidate a tetradic structure interpretation behind this covariant formulation. Regarding the effect of covariantisation at the level of the equations of motion, we explicitly show that the only physical change, in case of setting an arbitrary energy-momentum tensor to the right hand side, resides in the requirement of the fulfillment of the covariant conservation laws. Also, we have explicitly introduced the fundamental covariantly-conserved teleparallel tetrad for the symmetric teleparallel frameworks. |
gr-qc/0609096 | Gamal Nashed G.L. | Gamal G.L. Nashed | Kerr-Newman Solution and Energy in Teleparallel Equivalent of Einstein
Theory | 11 pages, Latex. Will appear in Mod. Phys. Lett. A | Mod.Phys.Lett.A22:1047-1056,2007 | 10.1142/S021773230702141X | null | gr-qc | null | An exact charged axially symmetric solution of the coupled gravitational and
electromagnetic fields in the teleparallel equivalent of Einstein theory is
derived. It is characterized by three parameters ``$ $the gravitational mass
$M$, the charge parameter $Q$ and the rotation parameter $a$" and its
associated metric gives Kerr-Newman spacetime. The parallel vector field and
the electromagnetic vector potential are axially symmetric. We then, calculate
the total energy using the gravitational energy-momentum. The energy is found
to be shared by its interior as well as exterior. Switching off the charge
parameter we find that no energy is shared by the exterior of the Kerr-Newman
black hole.
| [
{
"created": "Thu, 21 Sep 2006 22:32:47 GMT",
"version": "v1"
}
] | 2010-10-27 | [
[
"Nashed",
"Gamal G. L.",
""
]
] | An exact charged axially symmetric solution of the coupled gravitational and electromagnetic fields in the teleparallel equivalent of Einstein theory is derived. It is characterized by three parameters ``$ $the gravitational mass $M$, the charge parameter $Q$ and the rotation parameter $a$" and its associated metric gives Kerr-Newman spacetime. The parallel vector field and the electromagnetic vector potential are axially symmetric. We then, calculate the total energy using the gravitational energy-momentum. The energy is found to be shared by its interior as well as exterior. Switching off the charge parameter we find that no energy is shared by the exterior of the Kerr-Newman black hole. |
gr-qc/0502023 | Jiliang Jing | Jiliang Jing | Dirac Quasinormal modes of Schwarzschild black hole | 14 pages, 5 figures | Phys.Rev. D71 (2005) 124006 | 10.1103/PhysRevD.71.124006 | null | gr-qc astro-ph hep-th | null | The quasinormal modes (QNMs) associated with the decay of Dirac field
perturbation around a Schwarzschild black hole is investigated by using
continued fraction and Hill-determinant approaches. It is shown that the
fundamental quasinormal frequencies become evenly spaced for large angular
quantum number and the spacing is given by $\omega_{\lambda+1}-
\omega_{\lambda}=0.38490-0.00000i$. The angular quantum number has the
surprising effect of increasing real part of the quasinormal frequencies, but
it almost does not affect imaginary part, especially for low overtones. In
addition, the quasinormal frequencies also become evenly spaced for large
overtone number and the spacing for imaginary part is
$Im(\omega_{n+1})-Im(\omega_n)\approx -i/4M$ which is same as that of the
scalar, electromagnetic, and gravitational perturbations.
| [
{
"created": "Sun, 6 Feb 2005 04:11:34 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Jing",
"Jiliang",
""
]
] | The quasinormal modes (QNMs) associated with the decay of Dirac field perturbation around a Schwarzschild black hole is investigated by using continued fraction and Hill-determinant approaches. It is shown that the fundamental quasinormal frequencies become evenly spaced for large angular quantum number and the spacing is given by $\omega_{\lambda+1}- \omega_{\lambda}=0.38490-0.00000i$. The angular quantum number has the surprising effect of increasing real part of the quasinormal frequencies, but it almost does not affect imaginary part, especially for low overtones. In addition, the quasinormal frequencies also become evenly spaced for large overtone number and the spacing for imaginary part is $Im(\omega_{n+1})-Im(\omega_n)\approx -i/4M$ which is same as that of the scalar, electromagnetic, and gravitational perturbations. |
2010.15108 | Puskar Mondal | Puskar Mondal | The linear stability of the Einstein-Euler system on negative Einstein
spaces | null | null | null | null | gr-qc math-ph math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Here we prove the linear stability of a family of `$n+1$'-dimensional
Friedmann Lema\^{i}tre Robertson Walker (FLRW) cosmological models of general
relativity. We show that the solutions to the linearized Einstein-Euler field
equations around a class of FLRW metrics with compact spatial topology
(negative Einstein spaces and in particular hyperbolic for $n=3$) arising from
regular initial data remain uniformly bounded and decay to a family of metrics
with constant negative spatial scalar curvature. Utilizing a Hodge
decomposition of the fluid's $n-$velocity 1-form, the linearized Einstein-Euler
system becomes elliptic-hyperbolic (and non-autonomous) in the CMCSH gauge
facilitating an application of an energy type argument. Utilizing the estimates
derived from the associated elliptic equations, we first prove the uniform
boundedness of a Lyapunov functional (controlling appropriate norm of the data)
in the expanding direction. Utilizing the uniform boundedness, we later obtain
a sharp decay estimate which suggests that expansion of this particular
universe model may be sufficient to control the non-linearities (including
possible shock formation) of the Einstein-Euler system in a potential future
proof of the fully non-linear stability. In addition, the rotational and
harmonic parts of the fluid's $n-$velocity field couple to the remaining
degrees of freedom in higher orders, which once again indicates a
straightforward extension of current analysis to the fully non-linear setting
in the sufficiently small data limit. In addition, our results require a
certain integrability condition on the expansion factor and a suitable range of
the adiabatic index $\gamma_{a}$ ($(1,\frac{n+1}{n})$ i.e., $(1,\frac{4}{3})$
in the physically relevant `$3+1$' universe) if the equation of state
$p=(\gamma_{a}-1)\rho$ is chosen.
| [
{
"created": "Wed, 28 Oct 2020 17:50:46 GMT",
"version": "v1"
},
{
"created": "Sat, 7 Nov 2020 04:55:38 GMT",
"version": "v2"
},
{
"created": "Sun, 15 Nov 2020 20:56:54 GMT",
"version": "v3"
},
{
"created": "Tue, 8 Jun 2021 06:04:01 GMT",
"version": "v4"
},
{
"cre... | 2021-10-01 | [
[
"Mondal",
"Puskar",
""
]
] | Here we prove the linear stability of a family of `$n+1$'-dimensional Friedmann Lema\^{i}tre Robertson Walker (FLRW) cosmological models of general relativity. We show that the solutions to the linearized Einstein-Euler field equations around a class of FLRW metrics with compact spatial topology (negative Einstein spaces and in particular hyperbolic for $n=3$) arising from regular initial data remain uniformly bounded and decay to a family of metrics with constant negative spatial scalar curvature. Utilizing a Hodge decomposition of the fluid's $n-$velocity 1-form, the linearized Einstein-Euler system becomes elliptic-hyperbolic (and non-autonomous) in the CMCSH gauge facilitating an application of an energy type argument. Utilizing the estimates derived from the associated elliptic equations, we first prove the uniform boundedness of a Lyapunov functional (controlling appropriate norm of the data) in the expanding direction. Utilizing the uniform boundedness, we later obtain a sharp decay estimate which suggests that expansion of this particular universe model may be sufficient to control the non-linearities (including possible shock formation) of the Einstein-Euler system in a potential future proof of the fully non-linear stability. In addition, the rotational and harmonic parts of the fluid's $n-$velocity field couple to the remaining degrees of freedom in higher orders, which once again indicates a straightforward extension of current analysis to the fully non-linear setting in the sufficiently small data limit. In addition, our results require a certain integrability condition on the expansion factor and a suitable range of the adiabatic index $\gamma_{a}$ ($(1,\frac{n+1}{n})$ i.e., $(1,\frac{4}{3})$ in the physically relevant `$3+1$' universe) if the equation of state $p=(\gamma_{a}-1)\rho$ is chosen. |
2401.04770 | Georgios Doulis | Georgios Doulis, Sebastiano Bernuzzi, Wolfgang Tichy | Entropy based flux limiting scheme for conservation laws | 18 pages, 19 figures. arXiv admin note: text overlap with
arXiv:2202.08839 | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | The construction of high-resolution shock-capturing schemes is vital in
producing highly accurate gravitational waveforms from neutron star binaries.
The entropy based flux limiting (EFL) scheme is able to perform fast converging
binary neutron star merger simulations reaching up to fourth-order convergence
in the gravitational waveform phase. Here, we extend the applicability of the
EFL method beyond special/general relativistic hydrodynamics to scalar
conservation laws and show how to treat systems without a thermodynamic
entropy. This is an indication that the method has universal applicability to
any system of partial differential equations that can be written in
conservation form. We also present some further very challenging
special/general relativistic hydrodynamics applications of the EFL method and
use it to construct eccentricity reduced initial data for a specific neutron
star binary and show up to optimal fifth-order convergence in the gravitational
waveform phase for this simulation.
| [
{
"created": "Tue, 9 Jan 2024 19:00:15 GMT",
"version": "v1"
}
] | 2024-01-11 | [
[
"Doulis",
"Georgios",
""
],
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Tichy",
"Wolfgang",
""
]
] | The construction of high-resolution shock-capturing schemes is vital in producing highly accurate gravitational waveforms from neutron star binaries. The entropy based flux limiting (EFL) scheme is able to perform fast converging binary neutron star merger simulations reaching up to fourth-order convergence in the gravitational waveform phase. Here, we extend the applicability of the EFL method beyond special/general relativistic hydrodynamics to scalar conservation laws and show how to treat systems without a thermodynamic entropy. This is an indication that the method has universal applicability to any system of partial differential equations that can be written in conservation form. We also present some further very challenging special/general relativistic hydrodynamics applications of the EFL method and use it to construct eccentricity reduced initial data for a specific neutron star binary and show up to optimal fifth-order convergence in the gravitational waveform phase for this simulation. |
1902.08352 | Kai Lin | Kai Lin and Wei-Liang Qian | On matrix method for black hole quasinormal modes | null | Chinese Physics C, Vol. 43, No. 3 (2019) 035105 | 10.1088/1674-1137/43/3/035105 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we provide a comprehensive survey of possible applications of
the matrix method for black hole quasinormal modes. The proposed algorithm can
generally be applied to various background metrics, and in particular, it
accommodates for both analytic and numerical forms of the tortoise coordinates,
as well as black hole spacetimes. Our discussions give a detailed account of
different types of black hole metrics, master equations, and the corresponding
boundary conditions. Besides, we argue that the method can readily be applied
to cases where the master equation is a system of coupled equations. By
adjusting the number of interpolation points, the present method provides a
desirable degree of precision, in reasonable balance with its efficiency. The
method is flexible and can easily be adopted by various distinctive physical
scenarios.
| [
{
"created": "Fri, 22 Feb 2019 03:23:30 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Feb 2019 06:12:48 GMT",
"version": "v2"
}
] | 2019-02-28 | [
[
"Lin",
"Kai",
""
],
[
"Qian",
"Wei-Liang",
""
]
] | In this paper, we provide a comprehensive survey of possible applications of the matrix method for black hole quasinormal modes. The proposed algorithm can generally be applied to various background metrics, and in particular, it accommodates for both analytic and numerical forms of the tortoise coordinates, as well as black hole spacetimes. Our discussions give a detailed account of different types of black hole metrics, master equations, and the corresponding boundary conditions. Besides, we argue that the method can readily be applied to cases where the master equation is a system of coupled equations. By adjusting the number of interpolation points, the present method provides a desirable degree of precision, in reasonable balance with its efficiency. The method is flexible and can easily be adopted by various distinctive physical scenarios. |
0901.0892 | Sanjeev S. Seahra | Sanjeev S. Seahra, Christian G. Boehmer | Einstein static universes are unstable in generic f(R) models | 7 pages, 2 figures. Minor corrections. Minor changes and references
added to match version accepted by Phys. Rev. D | Phys.Rev.D79:064009,2009 | 10.1103/PhysRevD.79.064009 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study Einstein static universes in the context of generic f(R) models. It
is shown that Einstein static solutions exist for a wide variety of modified
gravity models sourced by a barotropic perfect fluid with equation of state
w=p/rho, but these solutions are always unstable to either homogeneous or
inhomogeneous perturbations. Our general results are in agreement with specific
models investigated in that past. We also discuss how our techniques can be
applied to other scenarios in f(R) gravity.
| [
{
"created": "Wed, 7 Jan 2009 18:50:00 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Feb 2009 15:56:32 GMT",
"version": "v2"
},
{
"created": "Sat, 14 Mar 2009 16:08:56 GMT",
"version": "v3"
}
] | 2009-03-14 | [
[
"Seahra",
"Sanjeev S.",
""
],
[
"Boehmer",
"Christian G.",
""
]
] | We study Einstein static universes in the context of generic f(R) models. It is shown that Einstein static solutions exist for a wide variety of modified gravity models sourced by a barotropic perfect fluid with equation of state w=p/rho, but these solutions are always unstable to either homogeneous or inhomogeneous perturbations. Our general results are in agreement with specific models investigated in that past. We also discuss how our techniques can be applied to other scenarios in f(R) gravity. |
2103.01693 | Paulo M. S\'a | Paulo M. S\'a | Late-time evolution of the Universe within a two-scalar-field
cosmological model | 15 pages, 4 figures | Phys. Rev. D 103, 123517 (2021) | 10.1103/PhysRevD.103.123517 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the late-time evolution of the Universe within a cosmological
model in which dark matter and dark energy are identified with two interacting
scalar fields. Using methods of qualitative analysis of dynamical systems, we
identify all cosmological solutions of this model. We show that viable
solutions -- in the sense that they correspond to a cosmic evolution in which a
long enough matter-dominated era is followed by a current era of accelerated
expansion -- can be found in several regions of the parameter space. These
solutions can be divided into two categories, namely, solutions that evolve to
a state of everlasting accelerated expansion, in which the energy density of
the dark-matter field rapidly approaches zero and the evolution becomes
entirely dominated by the dark-energy field, and solutions in which the stage
of accelerated expansion is temporary and the ratio between the energy
densities of dark energy and dark matter tends, asymptotically, to a constant
nonzero value.
| [
{
"created": "Tue, 2 Mar 2021 12:55:45 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Jun 2021 17:36:43 GMT",
"version": "v2"
}
] | 2021-06-14 | [
[
"Sá",
"Paulo M.",
""
]
] | We investigate the late-time evolution of the Universe within a cosmological model in which dark matter and dark energy are identified with two interacting scalar fields. Using methods of qualitative analysis of dynamical systems, we identify all cosmological solutions of this model. We show that viable solutions -- in the sense that they correspond to a cosmic evolution in which a long enough matter-dominated era is followed by a current era of accelerated expansion -- can be found in several regions of the parameter space. These solutions can be divided into two categories, namely, solutions that evolve to a state of everlasting accelerated expansion, in which the energy density of the dark-matter field rapidly approaches zero and the evolution becomes entirely dominated by the dark-energy field, and solutions in which the stage of accelerated expansion is temporary and the ratio between the energy densities of dark energy and dark matter tends, asymptotically, to a constant nonzero value. |
1609.07312 | B. S. Kandemir | B. S. Kandemir and \"Umit Ertem | Quasinormal modes of BTZ black hole and Hawking-like radiation in
graphene | 5 pages,1 figure | Annalen der Physik 529(4), 1600330 (2017) | 10.1002/andp.201600330 | null | gr-qc cond-mat.mes-hall | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Ba\~{n}ados-Teitelboim-Zanelli (BTZ) black hole model corresponds to a
solution of (2+1)-dimensional Einstein gravity with negative cosmological
constant, and by a conformal rescaling its metric can be mapped onto the
hyperbolic pseudosphere surface (Beltrami trumpet) with negative curvature.
Beltrami trumpet shaped graphene sheets have been predicted to emit Hawking
radiation that is experimentally detectable by a scanning tunnelling
microscope. Here, for the first time we present an analytical algorithm that
allows variational solutions to the Dirac Hamiltonian of graphene
pseudoparticles in BTZ black hole gravitational field by using an approach
based on the formalism of pseudo-Hermitian Hamiltonians within a
discrete-basis-set method. We show that our model not only reproduces the exact
results for the real part of quasinormal mode frequencies of (2+1)-dimensional
spinless BTZ black hole, but also provides analytical results for the real part
of quasinormal modes of spinning BTZ black hole, and also offers some
predictions for the observable effects with a view to gravity-like phenomena in
a curved graphene sheet.
| [
{
"created": "Fri, 23 Sep 2016 11:20:29 GMT",
"version": "v1"
}
] | 2017-04-26 | [
[
"Kandemir",
"B. S.",
""
],
[
"Ertem",
"Ümit",
""
]
] | The Ba\~{n}ados-Teitelboim-Zanelli (BTZ) black hole model corresponds to a solution of (2+1)-dimensional Einstein gravity with negative cosmological constant, and by a conformal rescaling its metric can be mapped onto the hyperbolic pseudosphere surface (Beltrami trumpet) with negative curvature. Beltrami trumpet shaped graphene sheets have been predicted to emit Hawking radiation that is experimentally detectable by a scanning tunnelling microscope. Here, for the first time we present an analytical algorithm that allows variational solutions to the Dirac Hamiltonian of graphene pseudoparticles in BTZ black hole gravitational field by using an approach based on the formalism of pseudo-Hermitian Hamiltonians within a discrete-basis-set method. We show that our model not only reproduces the exact results for the real part of quasinormal mode frequencies of (2+1)-dimensional spinless BTZ black hole, but also provides analytical results for the real part of quasinormal modes of spinning BTZ black hole, and also offers some predictions for the observable effects with a view to gravity-like phenomena in a curved graphene sheet. |
2403.14309 | Jan Tr\"ankle | Shyam Balaji, Guillem Dom\`enech, Gabriele Franciolini, Alexander
Ganz, Jan Tr\"ankle | Probing modified Hawking evaporation with gravitational waves from the
primordial black hole dominated universe | 18 pages+appendices, 7 figures | null | null | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been recently proposed that Hawking evaporation might slow down after
a black hole has lost about half of its mass. Such an effect, called "memory
burden", is parameterized as a suppression in the mass loss rate by negative
powers $n$ of the black hole entropy and could considerably extend the lifetime
of a black hole. We study the impact of memory burden on the Primordial Black
Hole (PBH) reheating scenario. Modified PBH evaporation leads to a
significantly longer PBH dominated stage. Requiring that PBHs evaporate prior
enough to Big Bang Nucleosynthesis shrinks the allowed PBH mass range. Indeed,
we find that for $n>2.5$ the PBH reheating scenario is not viable. The
frequency of the Gravitational Waves (GWs) induced by PBH number density
fluctuations is bound to be larger than about a Hz, while the amplitude of the
GW spectrum is enhanced due to the longer PBH dominated phase. Interestingly,
we show that, in some models, the slope of the induced GW spectrum might be
sensitive to the modifications to Hawking evaporation, proving it may be
possible to test the "memory burden" effect via induced GWs. Lastly, we argue
that our results could also apply to general modifications of Hawking
evaporation.
| [
{
"created": "Thu, 21 Mar 2024 11:30:57 GMT",
"version": "v1"
}
] | 2024-03-22 | [
[
"Balaji",
"Shyam",
""
],
[
"Domènech",
"Guillem",
""
],
[
"Franciolini",
"Gabriele",
""
],
[
"Ganz",
"Alexander",
""
],
[
"Tränkle",
"Jan",
""
]
] | It has been recently proposed that Hawking evaporation might slow down after a black hole has lost about half of its mass. Such an effect, called "memory burden", is parameterized as a suppression in the mass loss rate by negative powers $n$ of the black hole entropy and could considerably extend the lifetime of a black hole. We study the impact of memory burden on the Primordial Black Hole (PBH) reheating scenario. Modified PBH evaporation leads to a significantly longer PBH dominated stage. Requiring that PBHs evaporate prior enough to Big Bang Nucleosynthesis shrinks the allowed PBH mass range. Indeed, we find that for $n>2.5$ the PBH reheating scenario is not viable. The frequency of the Gravitational Waves (GWs) induced by PBH number density fluctuations is bound to be larger than about a Hz, while the amplitude of the GW spectrum is enhanced due to the longer PBH dominated phase. Interestingly, we show that, in some models, the slope of the induced GW spectrum might be sensitive to the modifications to Hawking evaporation, proving it may be possible to test the "memory burden" effect via induced GWs. Lastly, we argue that our results could also apply to general modifications of Hawking evaporation. |
1511.06161 | Jun-Qi Guo | Jun-Qi Guo and Pankaj S. Joshi | Spherical vacuum and scalar collapse for the Starobinsky R^2 model | 10 pages, 6 figures. Major change | Phys. Rev. D 94, 044063 (2016) | 10.1103/PhysRevD.94.044063 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spherical vacuum and scalar collapse for the Starobinsky R^2 model is
simulated. Obtained by considering the quantum-gravitational effects, this
model would admit some cases of singularity-free cosmological spacetimes. It is
found, however, that in vacuum and scalar collapse, when f' or the physical
scalar field is strong enough, a black hole including a central singularity can
be formed. In addition, near the central singularity, gravity dominates the
repulsion from the potential, so that in some circumstances the Ricci scalar is
pushed to infinity by gravity. Therefore, the semiclassical effects as included
here do not avoid the singularity problem in general relativity. A strong
physical scalar field can prevent the Ricci scalar from growing to infinity.
Vacuum collapse for the RlnR model is explored, and it is observed that for
this model the Ricci scalar can also go to infinity as the central singularity
is approached. Therefore, this feature seems universal in vacuum and scalar
collapse in f(R) gravity.
| [
{
"created": "Thu, 19 Nov 2015 13:30:28 GMT",
"version": "v1"
},
{
"created": "Sun, 29 Nov 2015 08:01:40 GMT",
"version": "v2"
},
{
"created": "Wed, 31 Aug 2016 16:30:22 GMT",
"version": "v3"
}
] | 2016-09-01 | [
[
"Guo",
"Jun-Qi",
""
],
[
"Joshi",
"Pankaj S.",
""
]
] | Spherical vacuum and scalar collapse for the Starobinsky R^2 model is simulated. Obtained by considering the quantum-gravitational effects, this model would admit some cases of singularity-free cosmological spacetimes. It is found, however, that in vacuum and scalar collapse, when f' or the physical scalar field is strong enough, a black hole including a central singularity can be formed. In addition, near the central singularity, gravity dominates the repulsion from the potential, so that in some circumstances the Ricci scalar is pushed to infinity by gravity. Therefore, the semiclassical effects as included here do not avoid the singularity problem in general relativity. A strong physical scalar field can prevent the Ricci scalar from growing to infinity. Vacuum collapse for the RlnR model is explored, and it is observed that for this model the Ricci scalar can also go to infinity as the central singularity is approached. Therefore, this feature seems universal in vacuum and scalar collapse in f(R) gravity. |
1606.06589 | Hooman Moradpour Hooman | Hooman Moradpour (RIAAM, Iran), Ines G. Salako (African Inst. Math.
Sci., Cape Town & Benin, IMSP & Ketou U.) | Thermodynamic analysis of the static spherically symmetric field
equations in Rastall theory | accepted by AHEP | null | 10.1155/2016/3492796 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The restrictions on the Rastall theory due to apply the Newtonian limit to
the theory are derived. In addition, we use the zero-zero component of the
Rastall field equations as well as the unified first law of thermodynamics to
find the Misner-Sharp mass content confined to the event horizon of the
spherically symmetric static spacetimes in the Rastall framework. The obtained
relation is calculated for the Schwarzschild and de-Sitter back holes as two
examples. Bearing the obtained relation for the Misner-Sharp mass in mind
together with recasting the one-one component of the Rastall field equations
into the form of the first law of thermodynamics, we obtain expressions for the
horizon entropy and the work term. Finally, we also compare the thermodynamic
quantities of system, including energy, entropy and work, with their
counterparts in the Einstein framework to have a better view about the role of
the Rastall hypothesis on the thermodynamics of system.
| [
{
"created": "Sun, 19 Jun 2016 13:20:15 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Sep 2016 08:12:29 GMT",
"version": "v2"
}
] | 2018-04-24 | [
[
"Moradpour",
"Hooman",
"",
"RIAAM, Iran"
],
[
"Salako",
"Ines G.",
"",
"African Inst. Math.\n Sci., Cape Town & Benin, IMSP & Ketou U."
]
] | The restrictions on the Rastall theory due to apply the Newtonian limit to the theory are derived. In addition, we use the zero-zero component of the Rastall field equations as well as the unified first law of thermodynamics to find the Misner-Sharp mass content confined to the event horizon of the spherically symmetric static spacetimes in the Rastall framework. The obtained relation is calculated for the Schwarzschild and de-Sitter back holes as two examples. Bearing the obtained relation for the Misner-Sharp mass in mind together with recasting the one-one component of the Rastall field equations into the form of the first law of thermodynamics, we obtain expressions for the horizon entropy and the work term. Finally, we also compare the thermodynamic quantities of system, including energy, entropy and work, with their counterparts in the Einstein framework to have a better view about the role of the Rastall hypothesis on the thermodynamics of system. |
0707.0876 | Yosef Zlochower | Badri Krishnan, Carlos O. Lousto, Yosef Zlochower | Quasi-Local Linear Momentum in Black-Hole Binaries | 5 pages, 3 figures, revtex4 | Phys.Rev.D76:081501,2007 | 10.1103/PhysRevD.76.081501 | null | gr-qc astro-ph | null | We propose a quasi-local formula for the linear momentum of black-hole
horizons inspired by the formalism of quasi-local horizons. We test this
formula using two complementary configurations: (i) by calculating the large
orbital linear momentum of the two black holes in an unequal-mass, zero-spin,
quasi-circular binary and (ii) by calculating the very small recoil momentum
imparted to the remnant of the head-on collision of an equal-mass,
anti-aligned-spin binary. We obtain results consistent with the horizon
trajectory in the orbiting case, and consistent with the net radiated linear
momentum for the much smaller head-on recoil velocity.
| [
{
"created": "Fri, 6 Jul 2007 19:53:23 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Oct 2007 15:44:42 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Krishnan",
"Badri",
""
],
[
"Lousto",
"Carlos O.",
""
],
[
"Zlochower",
"Yosef",
""
]
] | We propose a quasi-local formula for the linear momentum of black-hole horizons inspired by the formalism of quasi-local horizons. We test this formula using two complementary configurations: (i) by calculating the large orbital linear momentum of the two black holes in an unequal-mass, zero-spin, quasi-circular binary and (ii) by calculating the very small recoil momentum imparted to the remnant of the head-on collision of an equal-mass, anti-aligned-spin binary. We obtain results consistent with the horizon trajectory in the orbiting case, and consistent with the net radiated linear momentum for the much smaller head-on recoil velocity. |
2203.17080 | Pujian Mao | Pujian Mao and Weicheng Zhao | Notes on self-dual gravity | 11+4 pages; v2 minor revision, typos fixed; v3 minor typos corrected | JHEP 06 (2022) 081 | 10.1007/JHEP06(2022)081 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this paper, we study self-dual gravity in the Newman-Penrose formalism. We
specify the self-dual solution space from the Newman-Unti solutions. We show
that the asymptotic symmetries of the self-dual gravity are still the
(extended) BMS symmetries. We transform the self-dual Taub-NUT solution into
the Newman-Unti gauge in analytical form.
| [
{
"created": "Thu, 31 Mar 2022 14:52:37 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Jun 2022 02:43:22 GMT",
"version": "v2"
},
{
"created": "Mon, 5 Sep 2022 12:59:39 GMT",
"version": "v3"
}
] | 2022-09-07 | [
[
"Mao",
"Pujian",
""
],
[
"Zhao",
"Weicheng",
""
]
] | In this paper, we study self-dual gravity in the Newman-Penrose formalism. We specify the self-dual solution space from the Newman-Unti solutions. We show that the asymptotic symmetries of the self-dual gravity are still the (extended) BMS symmetries. We transform the self-dual Taub-NUT solution into the Newman-Unti gauge in analytical form. |
2404.14286 | Nihar Gupte | Nihar Gupte, Antoni Ramos-Buades, Alessandra Buonanno, Jonathan Gair,
M. Coleman Miller, Maximilian Dax, Stephen R. Green, Michael P\"urrer, Jonas
Wildberger, Jakob Macke, and Bernhard Sch\"olkopf | Evidence for eccentricity in the population of binary black holes
observed by LIGO-Virgo-KAGRA | 33 pages, 13 figures | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Binary black holes (BBHs) in eccentric orbits produce distinct modulations
the emitted gravitational waves (GWs). The measurement of orbital eccentricity
can provide robust evidence for dynamical binary formation channels. We analyze
57 GW events from the first, second and third observing runs of the
LIGO-Virgo-KAGRA (LVK) Collaboration using a multipolar aligned-spin
inspiral-merger-ringdown waveform model with two eccentric parameters:
eccentricity and relativistic anomaly. This is made computationally feasible
with the machine-learning code DINGO which accelerates inference by 2-3 orders
of magnitude compared to traditional inference. First, we find eccentric
aligned-spin versus quasi-circular aligned-spin $\log_{10}$ Bayes factors of
1.84 to 4.75 (depending on the glitch mitigation) for GW200129, 3.0 for
GW190701 and 1.77 for GW200208_22. We measure $e_{\text{gw}, 10Hz}$ to be
$0.27_{-0.12}^{+0.10}$ to $0.17_{-0.13}^{+0.14}$ for GW200129,
$0.35_{-0.11}^{+0.32}$ for GW190701 and $0.35_{-0.21}^{+0.18}$ for GW200208_22.
Second, we find $\log_{10}$ Bayes factors between the eccentric aligned-spin
versus quasi-circular precessing-spin hypothesis between 1.43 and 4.92 for
GW200129, 2.61 for GW190701 and 1.23 for GW200208_22. Third, our analysis does
not show evidence for eccentricity in GW190521, which has an eccentric
aligned-spin against quasi-circular aligned-spin $\log_{10}$ Bayes factor of
0.04. Fourth, we estimate that if we neglect the spin-precession and use an
astrophysical prior, the probability of one out of the 57 events being
eccentric is greater than 99.5% or $(100 - 8.4 \times 10^{-4})$% (depending on
the glitch mitigation). Fifth, we study the impact on parameter estimation when
neglecting either eccentricity or higher modes in eccentric models. These
results underscore the importance of including eccentric parameters in the
characterization of BBHs for GW detectors.
| [
{
"created": "Mon, 22 Apr 2024 15:37:08 GMT",
"version": "v1"
}
] | 2024-04-23 | [
[
"Gupte",
"Nihar",
""
],
[
"Ramos-Buades",
"Antoni",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Gair",
"Jonathan",
""
],
[
"Miller",
"M. Coleman",
""
],
[
"Dax",
"Maximilian",
""
],
[
"Green",
"Stephen R.",
... | Binary black holes (BBHs) in eccentric orbits produce distinct modulations the emitted gravitational waves (GWs). The measurement of orbital eccentricity can provide robust evidence for dynamical binary formation channels. We analyze 57 GW events from the first, second and third observing runs of the LIGO-Virgo-KAGRA (LVK) Collaboration using a multipolar aligned-spin inspiral-merger-ringdown waveform model with two eccentric parameters: eccentricity and relativistic anomaly. This is made computationally feasible with the machine-learning code DINGO which accelerates inference by 2-3 orders of magnitude compared to traditional inference. First, we find eccentric aligned-spin versus quasi-circular aligned-spin $\log_{10}$ Bayes factors of 1.84 to 4.75 (depending on the glitch mitigation) for GW200129, 3.0 for GW190701 and 1.77 for GW200208_22. We measure $e_{\text{gw}, 10Hz}$ to be $0.27_{-0.12}^{+0.10}$ to $0.17_{-0.13}^{+0.14}$ for GW200129, $0.35_{-0.11}^{+0.32}$ for GW190701 and $0.35_{-0.21}^{+0.18}$ for GW200208_22. Second, we find $\log_{10}$ Bayes factors between the eccentric aligned-spin versus quasi-circular precessing-spin hypothesis between 1.43 and 4.92 for GW200129, 2.61 for GW190701 and 1.23 for GW200208_22. Third, our analysis does not show evidence for eccentricity in GW190521, which has an eccentric aligned-spin against quasi-circular aligned-spin $\log_{10}$ Bayes factor of 0.04. Fourth, we estimate that if we neglect the spin-precession and use an astrophysical prior, the probability of one out of the 57 events being eccentric is greater than 99.5% or $(100 - 8.4 \times 10^{-4})$% (depending on the glitch mitigation). Fifth, we study the impact on parameter estimation when neglecting either eccentricity or higher modes in eccentric models. These results underscore the importance of including eccentric parameters in the characterization of BBHs for GW detectors. |
1301.6060 | Igor I. Smolyaninov | Igor I. Smolyaninov | Extra-dimensional metamaterials: simple models of inflation and metric
signature transitions | 14 pages, 1 figure | Universe 3,66 (2017) | 10.3390/universe3030066 | null | gr-qc physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Lattices of topological defects, such as Abrikosov lattices and domain wall
lattices often arise as metastable ground states in higher-dimensional field
theoretical models. We demonstrate that such lattice states may be described as
extra-dimensional metamaterials via higher-dimensional effective medium theory.
A 4+1 dimensional extension of Maxwell electrodynamics with a compactified
time-like dimension has been considered as an example. It is demonstrated that
from the point of view of macroscopic electrodynamics an Abrikosov lattice
state in such a 4+1 dimensional spacetime may be described as a uniaxial
hyperbolic metamaterial. Extraordinary photons perceive this medium as a 3+1
dimensional Minkowski spacetime in which one of the original spatial dimensions
(the optical axis of the metamaterial) plays the role of a new time-like
coordinate. Since metric signature of this effective space-time depends on the
Abrikosov lattice periodicity, the described model may be useful in studying
metric signature transitions. A particular kind of metric signature transition
understood as a macroscopic medium effect may emulate cosmological inflation.
| [
{
"created": "Fri, 25 Jan 2013 15:10:59 GMT",
"version": "v1"
}
] | 2017-09-22 | [
[
"Smolyaninov",
"Igor I.",
""
]
] | Lattices of topological defects, such as Abrikosov lattices and domain wall lattices often arise as metastable ground states in higher-dimensional field theoretical models. We demonstrate that such lattice states may be described as extra-dimensional metamaterials via higher-dimensional effective medium theory. A 4+1 dimensional extension of Maxwell electrodynamics with a compactified time-like dimension has been considered as an example. It is demonstrated that from the point of view of macroscopic electrodynamics an Abrikosov lattice state in such a 4+1 dimensional spacetime may be described as a uniaxial hyperbolic metamaterial. Extraordinary photons perceive this medium as a 3+1 dimensional Minkowski spacetime in which one of the original spatial dimensions (the optical axis of the metamaterial) plays the role of a new time-like coordinate. Since metric signature of this effective space-time depends on the Abrikosov lattice periodicity, the described model may be useful in studying metric signature transitions. A particular kind of metric signature transition understood as a macroscopic medium effect may emulate cosmological inflation. |
1509.01572 | Andreas Kreienbuehl | Andreas Kreienbuehl and Pietro Benedusi and Daniel Ruprecht and Rolf
Krause | Time parallel gravitational collapse simulation | 16 pages, 8 figures, 1 listing, and 1 table | Communications in Applied Mathematics and Computational Science
12-1 (2017), 109--128 | 10.2140/camcos.2017.12.109 | null | gr-qc cs.CE cs.DC cs.PF | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article demonstrates the applicability of the parallel-in-time method
Parareal to the numerical solution of the Einstein gravity equations for the
spherical collapse of a massless scalar field. To account for the shrinking of
the spatial domain in time, a tailored load balancing scheme is proposed and
compared to load balancing based on number of time steps alone. The performance
of Parareal is studied for both the sub-critical and black hole case; our
experiments show that Parareal generates substantial speedup and, in the
super-critical regime, can reproduce Choptuik's black hole mass scaling law.
| [
{
"created": "Fri, 4 Sep 2015 19:32:45 GMT",
"version": "v1"
},
{
"created": "Sun, 24 Apr 2016 19:18:58 GMT",
"version": "v2"
},
{
"created": "Wed, 28 Dec 2016 22:06:40 GMT",
"version": "v3"
}
] | 2017-05-23 | [
[
"Kreienbuehl",
"Andreas",
""
],
[
"Benedusi",
"Pietro",
""
],
[
"Ruprecht",
"Daniel",
""
],
[
"Krause",
"Rolf",
""
]
] | This article demonstrates the applicability of the parallel-in-time method Parareal to the numerical solution of the Einstein gravity equations for the spherical collapse of a massless scalar field. To account for the shrinking of the spatial domain in time, a tailored load balancing scheme is proposed and compared to load balancing based on number of time steps alone. The performance of Parareal is studied for both the sub-critical and black hole case; our experiments show that Parareal generates substantial speedup and, in the super-critical regime, can reproduce Choptuik's black hole mass scaling law. |
2205.00425 | Peng-Cheng Li | Tieguang Zi, Ziqi Zhou, Hai-Tian Wang, Peng-Cheng Li, Jian-dong Zhang
and Bin Chen | Analytic Kludge Waveforms for Extreme Mass Ratio Inspirals of Charged
Object around Kerr-Newman Black Hole | 15 pages, 7 figures, nb source is available, minor changes, to be
published in PRD | null | 10.1103/PhysRevD.107.023005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the approximate, ``analytic-kludge'' (AK) waveforms for the
inspiral of a charged stellar-mass compact object (CO) into a charged massive
Kerr-Newman (KN) black hole (BH). The modifications of the inspiral orbit due
to the charges in this system can be attributed to three sources: the electric
force between the CO and the MBH, the energy flow of the dipole electromagnetic
radiation, and the deformation of the metric caused by the charge of the MBH.
All these are encoded explicitly in the fundamental frequencies of the orbits,
which are calculated analytically in the weak-field regime. By calculating the
mismatch between the waveforms for charged and neutral EMRI systems with
respect to space-borne detectors TianQin and LISA, we show that tiny charges in
the system can produce distinct imprints on the waveforms. Finally, we perform
parameter estimation for the charges using the Fisher information matrix method
and find that the precision can reach the level of $10^{-5}$ in suitable
scenarios. We also study the effects of charges on the parameter estimation of
charge, where the effects from the charge of the MBH can be well explained by
its effects on the cutoff of the inspiral.
| [
{
"created": "Sun, 1 May 2022 09:01:44 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Nov 2022 08:54:56 GMT",
"version": "v2"
},
{
"created": "Wed, 4 Jan 2023 07:04:38 GMT",
"version": "v3"
}
] | 2023-01-25 | [
[
"Zi",
"Tieguang",
""
],
[
"Zhou",
"Ziqi",
""
],
[
"Wang",
"Hai-Tian",
""
],
[
"Li",
"Peng-Cheng",
""
],
[
"Zhang",
"Jian-dong",
""
],
[
"Chen",
"Bin",
""
]
] | We derive the approximate, ``analytic-kludge'' (AK) waveforms for the inspiral of a charged stellar-mass compact object (CO) into a charged massive Kerr-Newman (KN) black hole (BH). The modifications of the inspiral orbit due to the charges in this system can be attributed to three sources: the electric force between the CO and the MBH, the energy flow of the dipole electromagnetic radiation, and the deformation of the metric caused by the charge of the MBH. All these are encoded explicitly in the fundamental frequencies of the orbits, which are calculated analytically in the weak-field regime. By calculating the mismatch between the waveforms for charged and neutral EMRI systems with respect to space-borne detectors TianQin and LISA, we show that tiny charges in the system can produce distinct imprints on the waveforms. Finally, we perform parameter estimation for the charges using the Fisher information matrix method and find that the precision can reach the level of $10^{-5}$ in suitable scenarios. We also study the effects of charges on the parameter estimation of charge, where the effects from the charge of the MBH can be well explained by its effects on the cutoff of the inspiral. |
gr-qc/9602041 | R. Loll | R. Loll (INFN, Firenze) | A real alternative to quantum gravity in loop space | 11 pages, plain TeX, Feb 96 | Phys.Rev.D54:5381-5384,1996 | 10.1103/PhysRevD.54.5381 | DFF 244/02/96 | gr-qc hep-th | null | We show that the Hamiltonian of four-dimensional Lorentzian gravity, defined
on a space of real, SU(2)-valued connections, in spite of its non-polynomiality
possesses a natural quantum analogue in a lattice-discretized formulation of
the theory. This opens the way for a systematic investigation of its spectrum.
The unambiguous and well-defined scalar product is that of the SU(2)-gauge
theory. We also comment on various aspects of the continuum theory.
| [
{
"created": "Wed, 21 Feb 1996 16:46:17 GMT",
"version": "v1"
}
] | 2011-09-09 | [
[
"Loll",
"R.",
"",
"INFN, Firenze"
]
] | We show that the Hamiltonian of four-dimensional Lorentzian gravity, defined on a space of real, SU(2)-valued connections, in spite of its non-polynomiality possesses a natural quantum analogue in a lattice-discretized formulation of the theory. This opens the way for a systematic investigation of its spectrum. The unambiguous and well-defined scalar product is that of the SU(2)-gauge theory. We also comment on various aspects of the continuum theory. |
gr-qc/0408052 | Sergey Kozyrev | S. Kozyrev | Static spherically symmetric constant density relativistic and Newtonian
stars in the Lobachevskyan geometry | 10 pages | null | null | null | gr-qc | null | The present paper has the purpose to illustrate the importance of the ideas
and constructions of the Non-Euclidean (Lobachevsky) Geometry, which can be
applied even today for solving some conceptually important problems. We study
the static and spherically symmetric solutions to the Einstein field equations
under the assumption that the space-time may possess an arbitrary number of
spatial dimensions. A new exact solution of a perfect fluid sphere of constant
(homogeneous) energy-density which agrees with interior Lobachevsky geometry
for 3D and 4D spaces are found. We discuss the property of temporal scalar
field arise in lower-dimensional theories as the reduction of extra dimension.
| [
{
"created": "Tue, 17 Aug 2004 08:49:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Kozyrev",
"S.",
""
]
] | The present paper has the purpose to illustrate the importance of the ideas and constructions of the Non-Euclidean (Lobachevsky) Geometry, which can be applied even today for solving some conceptually important problems. We study the static and spherically symmetric solutions to the Einstein field equations under the assumption that the space-time may possess an arbitrary number of spatial dimensions. A new exact solution of a perfect fluid sphere of constant (homogeneous) energy-density which agrees with interior Lobachevsky geometry for 3D and 4D spaces are found. We discuss the property of temporal scalar field arise in lower-dimensional theories as the reduction of extra dimension. |
2210.15564 | Lang Liu | Zu-Cheng Chen, Sang Pyo Kim and Lang Liu | Gravitational and electromagnetic radiation from binary black holes with
electric and magnetic charges: Hyperbolic orbits on a cone | 21 pages, 2 figures; | Communications in Theoretical Physics (2023) | 10.1088/1572-9494/acce98 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the hyperbolic orbit of binary black holes with electric and
magnetic charges. In the low-velocity and weak-field regime, by using the
Newtonian method, we calculate the total emission rate of energy due to
gravitational and electromagnetic radiation from binary black holes with
electric and magnetic charges in hyperbolic orbits. Moreover, we develop a
formalism to derive the merger rate of binary black holes with electric and
magnetic charges from the two-body dynamical capture. We apply the formalism to
investigate the effects of the charges on the merger rate for the near-extremal
case and find that the effects cannot be ignored.
| [
{
"created": "Thu, 27 Oct 2022 15:56:57 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Jun 2023 15:43:11 GMT",
"version": "v2"
}
] | 2023-06-09 | [
[
"Chen",
"Zu-Cheng",
""
],
[
"Kim",
"Sang Pyo",
""
],
[
"Liu",
"Lang",
""
]
] | We derive the hyperbolic orbit of binary black holes with electric and magnetic charges. In the low-velocity and weak-field regime, by using the Newtonian method, we calculate the total emission rate of energy due to gravitational and electromagnetic radiation from binary black holes with electric and magnetic charges in hyperbolic orbits. Moreover, we develop a formalism to derive the merger rate of binary black holes with electric and magnetic charges from the two-body dynamical capture. We apply the formalism to investigate the effects of the charges on the merger rate for the near-extremal case and find that the effects cannot be ignored. |
2109.02844 | Wei-Liang Qian | Wei-Liang Qian, Kai Lin, Xiao-Mei Kuang, Bin Wang, and Rui-Hong Yue | Quasinormal modes in two-photon autocorrelation and the geometric-optics
approximation | 12 pages, 3 figures | null | 10.1140/epjc/s10052-022-10155-w | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we study the black hole light echoes in terms of the two-photon
autocorrelation and explore their connection with the quasinormal modes. It is
shown that the above time-domain phenomenon can be analyzed by utilizing the
well-known frequency-domain relations between the quasinormal modes and
characteristic parameters of null geodesics. We found that the time-domain
correlator, obtained by the inverse Fourier transform, naturally acquires the
echo feature, which can be attributed to a collective effect of the asymptotic
poles through a weighted summation of the squared modulus of the relevant
Green's functions. Specifically, the contour integral leads to a summation
taking over both the overtone index and angular momentum. Moreover, the
dominant contributions to the light echoes are from those in the eikonal limit,
consistent with the existing findings using the geometric-optics arguments. For
the Schwarzschild black holes, we demonstrate the results numerically by
considering a transient spherical light source. Also, for the Kerr spacetimes,
we point out a potential difference between the resulting light echoes using
the geometric-optics approach and those obtained by the black hole perturbation
theory. Possible astrophysical implications of the present study are addressed.
| [
{
"created": "Tue, 7 Sep 2021 03:55:51 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Jan 2022 18:01:28 GMT",
"version": "v2"
},
{
"created": "Fri, 11 Feb 2022 14:06:20 GMT",
"version": "v3"
}
] | 2022-03-14 | [
[
"Qian",
"Wei-Liang",
""
],
[
"Lin",
"Kai",
""
],
[
"Kuang",
"Xiao-Mei",
""
],
[
"Wang",
"Bin",
""
],
[
"Yue",
"Rui-Hong",
""
]
] | In this work, we study the black hole light echoes in terms of the two-photon autocorrelation and explore their connection with the quasinormal modes. It is shown that the above time-domain phenomenon can be analyzed by utilizing the well-known frequency-domain relations between the quasinormal modes and characteristic parameters of null geodesics. We found that the time-domain correlator, obtained by the inverse Fourier transform, naturally acquires the echo feature, which can be attributed to a collective effect of the asymptotic poles through a weighted summation of the squared modulus of the relevant Green's functions. Specifically, the contour integral leads to a summation taking over both the overtone index and angular momentum. Moreover, the dominant contributions to the light echoes are from those in the eikonal limit, consistent with the existing findings using the geometric-optics arguments. For the Schwarzschild black holes, we demonstrate the results numerically by considering a transient spherical light source. Also, for the Kerr spacetimes, we point out a potential difference between the resulting light echoes using the geometric-optics approach and those obtained by the black hole perturbation theory. Possible astrophysical implications of the present study are addressed. |
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