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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1610.01202 | Deng Wang | Deng Wang and Xin-He Meng | Model-independent determination on $H_0$ using the latest $H(z)$ data | null | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform the improved constraints on the Hubble constant $H_0$ by using the
model-independent method, Gaussian Processes. Utilizing the latest 36 $H(z)$
measurements, we obtain $H_0=69.21\pm3.72$ km s$^{-1}$ Mpc$^{-1}$, which is
consistent with the Planck 2015 and Riess et al. 2016 analysis at $1\sigma$
confidence level, and reduces the uncertainty from $6.5\%$ (Busti et al. 2014)
to $5.4\%$. Different from the results of Busti et al. 2014 by only using 19
$H(z)$ measurements, our reconstruction results of $H(z)$ and the derived
values of $H_0$ are independent of the choice of covariance functions.
| [
{
"created": "Sat, 1 Oct 2016 14:17:12 GMT",
"version": "v1"
}
] | 2016-10-06 | [
[
"Wang",
"Deng",
""
],
[
"Meng",
"Xin-He",
""
]
] | We perform the improved constraints on the Hubble constant $H_0$ by using the model-independent method, Gaussian Processes. Utilizing the latest 36 $H(z)$ measurements, we obtain $H_0=69.21\pm3.72$ km s$^{-1}$ Mpc$^{-1}$, which is consistent with the Planck 2015 and Riess et al. 2016 analysis at $1\sigma$ confidence level, and reduces the uncertainty from $6.5\%$ (Busti et al. 2014) to $5.4\%$. Different from the results of Busti et al. 2014 by only using 19 $H(z)$ measurements, our reconstruction results of $H(z)$ and the derived values of $H_0$ are independent of the choice of covariance functions. |
2006.06468 | Raviteja Konka | Konka Raviteja, Sashideep Gutti | Marginally trapped and anti-trapped surfaces for matter evolution in
D-dimensions | 14 pages, 12 figures | Phys. Rev. D 102, 024072 (2020) | 10.1103/PhysRevD.102.024072 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we explore the formation of the marginally trapped and
marginally anti-trapped surfaces that arise from the evolution of homogeneous
dust in D-dimensions with and without the cosmological constant, this is seen
through the analytical expressions for such surfaces. We obtain closed form
expressions for the Norm of the normal to the Horizon that decides their causal
nature and also look at several interesting features of these surface evolution
that are significantly different from the four dimensional counterpart. We
obtain the expressions for the Ashtekar-Badrikrihnan's Area-balance law for
dynamical horizon (spacelike surface) tailored for the case of spherically
symmetric dust evolution in D-dimensions.
| [
{
"created": "Wed, 10 Jun 2020 16:02:23 GMT",
"version": "v1"
}
] | 2020-07-29 | [
[
"Raviteja",
"Konka",
""
],
[
"Gutti",
"Sashideep",
""
]
] | In this paper, we explore the formation of the marginally trapped and marginally anti-trapped surfaces that arise from the evolution of homogeneous dust in D-dimensions with and without the cosmological constant, this is seen through the analytical expressions for such surfaces. We obtain closed form expressions for the Norm of the normal to the Horizon that decides their causal nature and also look at several interesting features of these surface evolution that are significantly different from the four dimensional counterpart. We obtain the expressions for the Ashtekar-Badrikrihnan's Area-balance law for dynamical horizon (spacelike surface) tailored for the case of spherically symmetric dust evolution in D-dimensions. |
1012.2433 | Balakin Alexander | Alexander B. Balakin and Vladimir V. Bochkarev | Archimedean-type force in a cosmic dark fluid: II. Qualitative and
numerical study of a multistage Universe expansion | 15 pages, 12 figures, Part II, typos corrected, Fig.4 replaced,
references corrected | Phys.Rev.D83:024036,2011 | 10.1103/PhysRevD.83.024036 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this (second) part of the work we present the results of numerical and
qualitative analysis, based on a new model of the Archimedean-type interaction
between dark matter and dark energy. The Archimedean-type force is linear in
the four-gradient of the dark energy pressure and plays a role of
self-regulator of the energy redistribution in a cosmic dark fluid. Because of
the Archimedean-type interaction the cosmological evolution is shown to have a
multistage character. Depending on the choice of the values of the model
guiding parameters,the Universe's expansion is shown to be perpetually
accelerated, periodic or quasiperiodic with finite number of
deceleration/acceleration epochs. We distinguished the models, which can be
definitely characterized by the inflation in the early Universe, by the
late-time accelerated expansion and nonsingular behavior in intermediate
epochs, and classified them with respect to a number of transition points.
Transition points appear, when the acceleration parameter changes the sign,
providing the natural partition of the Universe's history into epochs of
accelerated and decelerated expansion. The strategy and results of numerical
calculations are advocated by the qualitative analysis of the instantaneous
phase portraits of the dynamic system associated with the key equation for the
dark energy pressure evolution.
| [
{
"created": "Sat, 11 Dec 2010 07:54:49 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Feb 2011 18:12:48 GMT",
"version": "v2"
}
] | 2011-02-28 | [
[
"Balakin",
"Alexander B.",
""
],
[
"Bochkarev",
"Vladimir V.",
""
]
] | In this (second) part of the work we present the results of numerical and qualitative analysis, based on a new model of the Archimedean-type interaction between dark matter and dark energy. The Archimedean-type force is linear in the four-gradient of the dark energy pressure and plays a role of self-regulator of the energy redistribution in a cosmic dark fluid. Because of the Archimedean-type interaction the cosmological evolution is shown to have a multistage character. Depending on the choice of the values of the model guiding parameters,the Universe's expansion is shown to be perpetually accelerated, periodic or quasiperiodic with finite number of deceleration/acceleration epochs. We distinguished the models, which can be definitely characterized by the inflation in the early Universe, by the late-time accelerated expansion and nonsingular behavior in intermediate epochs, and classified them with respect to a number of transition points. Transition points appear, when the acceleration parameter changes the sign, providing the natural partition of the Universe's history into epochs of accelerated and decelerated expansion. The strategy and results of numerical calculations are advocated by the qualitative analysis of the instantaneous phase portraits of the dynamic system associated with the key equation for the dark energy pressure evolution. |
2308.02250 | Lavinia Heisenberg | Fabio D'Ambrosio, Lavinia Heisenberg and Stefan Zentarra | Hamiltonian Analysis of $f(Q)$ Gravity and the Failure of the
Dirac-Bergmann Algorithm for Teleparallel Theories of Gravity | 45 pages, 3 figues, Comments are welcome | null | null | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | In recent years, $f(Q)$ gravity has enjoyed considerable attention in the
literature and important results have been obtained. However, the question of
how many physical degrees of freedom the theory propagates -- and how this
number may depend on the form of the function $f$ -- has not been answered
satisfactorily. In this article we show that a Hamiltonian analysis based on
the Dirac-Bergmann algorithm -- one of the standard methods to address this
type of question -- fails. We isolate the source of the failure, show that
other commonly considered teleparallel theories of gravity are affected by the
same problem, and we point out that the number of degrees of freedom obtained
in Phys. Rev. D 106 no. 4, (2022) by K. Hu, T. Katsuragawa, and T. Qui (namely
eight), based on the Dirac-Bergmann algorithm, is wrong. Using a different
approach, we show that the upper bound on the degrees of freedom is seven.
Finally, we propose a more promising strategy for settling this important
question.
| [
{
"created": "Fri, 4 Aug 2023 11:15:59 GMT",
"version": "v1"
}
] | 2023-08-07 | [
[
"D'Ambrosio",
"Fabio",
""
],
[
"Heisenberg",
"Lavinia",
""
],
[
"Zentarra",
"Stefan",
""
]
] | In recent years, $f(Q)$ gravity has enjoyed considerable attention in the literature and important results have been obtained. However, the question of how many physical degrees of freedom the theory propagates -- and how this number may depend on the form of the function $f$ -- has not been answered satisfactorily. In this article we show that a Hamiltonian analysis based on the Dirac-Bergmann algorithm -- one of the standard methods to address this type of question -- fails. We isolate the source of the failure, show that other commonly considered teleparallel theories of gravity are affected by the same problem, and we point out that the number of degrees of freedom obtained in Phys. Rev. D 106 no. 4, (2022) by K. Hu, T. Katsuragawa, and T. Qui (namely eight), based on the Dirac-Bergmann algorithm, is wrong. Using a different approach, we show that the upper bound on the degrees of freedom is seven. Finally, we propose a more promising strategy for settling this important question. |
2307.00506 | Tetsuya Shiromizu | Tetsuya Shiromizu, Keisuke Izumi | Attractive gravity probe surface with positive cosmological constant | 14 pages, version accepted to PTEP | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In four dimensional spacetimes with a positive cosmological constant, we
introduce a new geometrical object associated with the cosmological horizon and
then show the areal inequality. We also examine the attractive gravity probe
surfaces as an indicator for the existence of attractive gravity.
| [
{
"created": "Sun, 2 Jul 2023 07:44:44 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Sep 2023 01:24:42 GMT",
"version": "v2"
}
] | 2023-09-22 | [
[
"Shiromizu",
"Tetsuya",
""
],
[
"Izumi",
"Keisuke",
""
]
] | In four dimensional spacetimes with a positive cosmological constant, we introduce a new geometrical object associated with the cosmological horizon and then show the areal inequality. We also examine the attractive gravity probe surfaces as an indicator for the existence of attractive gravity. |
1807.02461 | Ramin G. Daghigh | Ramin G. Daghigh, Michael D. Green, Gabor Kunstatter | Quantum Mechanics of the Interior of the Russo-Susskind-Thorlacius Black
Hole | 15 pages, 5 figures, accepted for publication in PRD | Phys. Rev. D 98, 124017 (2018) | 10.1103/PhysRevD.98.124017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the quantum mechanics of homogeneous black hole interiors in the RST
model of 2D gravity. The model, which contains a dilaton and metric, includes
radiation back-reaction terms and is exactly solvable classically. The reduced
phase space is four dimensional. The equations for one pair of variables can be
trivially solved. The dynamics of the remaining degree of freedom, namely the
dilaton, is more interesting and corresponds to that of a particle on the half
line in a linear potential with time dependent coupling. We construct the
self-adjoint extension of the corresponding quantized Hamiltonian and
numerically solve the time dependent Schr$\ddot{\mbox{o}}$dinger equation for
Gaussian initial data. As expected the singularity is resolved and the
expectation value of the dilaton oscillates between a minimum and maximum,
which both gradually decrease with time due to the time dependence in the
potential. In the classical black hole spacetime, the maximum value of the
dilaton corresponds to the size of the horizon while the minimum is the
singularity. The quantum dynamics, therefore, corresponds at the semi-classical
level to an evaporating black hole. The rate of quantum fluctuations increases
as the system evolves but intriguingly, at longer times the expectation value
of the radius undergoes "revivals" in which the amplitude of oscillations
between minimum and maximum temporarily increases. These revivals are also
characteristic of the quantum dynamics of the {\it time independent} quantum
linear potential.
| [
{
"created": "Fri, 6 Jul 2018 15:44:03 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Dec 2018 19:20:44 GMT",
"version": "v2"
}
] | 2018-12-26 | [
[
"Daghigh",
"Ramin G.",
""
],
[
"Green",
"Michael D.",
""
],
[
"Kunstatter",
"Gabor",
""
]
] | We study the quantum mechanics of homogeneous black hole interiors in the RST model of 2D gravity. The model, which contains a dilaton and metric, includes radiation back-reaction terms and is exactly solvable classically. The reduced phase space is four dimensional. The equations for one pair of variables can be trivially solved. The dynamics of the remaining degree of freedom, namely the dilaton, is more interesting and corresponds to that of a particle on the half line in a linear potential with time dependent coupling. We construct the self-adjoint extension of the corresponding quantized Hamiltonian and numerically solve the time dependent Schr$\ddot{\mbox{o}}$dinger equation for Gaussian initial data. As expected the singularity is resolved and the expectation value of the dilaton oscillates between a minimum and maximum, which both gradually decrease with time due to the time dependence in the potential. In the classical black hole spacetime, the maximum value of the dilaton corresponds to the size of the horizon while the minimum is the singularity. The quantum dynamics, therefore, corresponds at the semi-classical level to an evaporating black hole. The rate of quantum fluctuations increases as the system evolves but intriguingly, at longer times the expectation value of the radius undergoes "revivals" in which the amplitude of oscillations between minimum and maximum temporarily increases. These revivals are also characteristic of the quantum dynamics of the {\it time independent} quantum linear potential. |
1406.1456 | Antonino Marciano | Stephon Alexander, Yi-Fu Cai and Antonino Marciano | Fermi-bounce cosmology and the fermion curvaton mechanism | 9 pages, 4 figures | null | 10.1016/j.physletb.2015.04.026 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A nonsingular bouncing cosmology can be achieved by introducing a fermion
field with BCS condensation occurring at high energy scales. In this paper we
are able to dilute the anisotropic stress near the bounce by means of releasing
the gap energy density near the phase transition between the radiation and
condensate states. In order to explain the nearly scale-invariant CMB spectrum,
another fermion field is required. We investigate one possible curvaton
mechanism by involving one another fermion field without condensation where the
mass is lighter than the background field. We show that, by virtue of the
fermion curvaton mechanism, our model can satisfy the latest cosmological
observations very well, and that the fermion species involved may realize a
cosmological see-saw mechanism after one finely tunes model parameters.
| [
{
"created": "Thu, 5 Jun 2014 17:38:18 GMT",
"version": "v1"
}
] | 2015-05-20 | [
[
"Alexander",
"Stephon",
""
],
[
"Cai",
"Yi-Fu",
""
],
[
"Marciano",
"Antonino",
""
]
] | A nonsingular bouncing cosmology can be achieved by introducing a fermion field with BCS condensation occurring at high energy scales. In this paper we are able to dilute the anisotropic stress near the bounce by means of releasing the gap energy density near the phase transition between the radiation and condensate states. In order to explain the nearly scale-invariant CMB spectrum, another fermion field is required. We investigate one possible curvaton mechanism by involving one another fermion field without condensation where the mass is lighter than the background field. We show that, by virtue of the fermion curvaton mechanism, our model can satisfy the latest cosmological observations very well, and that the fermion species involved may realize a cosmological see-saw mechanism after one finely tunes model parameters. |
1309.4066 | Charles Wang | C. H.-T. Wang, J. A. Reid, A. St J. Murphy, D. Rodrigues, M. Al Alawi,
R. Bingham, J. T. Mendonca, T. B. Davies | A consistent scalar-tensor cosmology for inflation, dark energy and the
Hubble parameter | 6 pages; version accepted by PLA | Physics Letters A 380 (2016) 3761-3765 | 10.1016/j.physleta.2016.09.038 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A Friedman cosmology is investigated based on scalar-tensor gravitation with
general metric coupling and scalar potential functions. We show that for a
broad class of such functions, the scalar field can be dynamically trapped
using a recently suggested mechanism. The trapped scalar can drive inflation
and accelerated cosmic expansion, compatible with standard requirements. The
inflationary phase admits a natural exit with a value of the Hubble parameter
dictated by the duration of inflation in a parameter independent manner. For
inflationary duration consistent with the GUT description, the resulting Hubble
parameter is found to be consistent with its observed value.
| [
{
"created": "Mon, 16 Sep 2013 18:50:42 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Apr 2016 16:17:15 GMT",
"version": "v2"
},
{
"created": "Thu, 22 Sep 2016 14:58:14 GMT",
"version": "v3"
}
] | 2016-10-05 | [
[
"Wang",
"C. H. -T.",
""
],
[
"Reid",
"J. A.",
""
],
[
"Murphy",
"A. St J.",
""
],
[
"Rodrigues",
"D.",
""
],
[
"Alawi",
"M. Al",
""
],
[
"Bingham",
"R.",
""
],
[
"Mendonca",
"J. T.",
""
],
[
"Davies",
"T. B.",
""
]
] | A Friedman cosmology is investigated based on scalar-tensor gravitation with general metric coupling and scalar potential functions. We show that for a broad class of such functions, the scalar field can be dynamically trapped using a recently suggested mechanism. The trapped scalar can drive inflation and accelerated cosmic expansion, compatible with standard requirements. The inflationary phase admits a natural exit with a value of the Hubble parameter dictated by the duration of inflation in a parameter independent manner. For inflationary duration consistent with the GUT description, the resulting Hubble parameter is found to be consistent with its observed value. |
2303.10376 | Vinod Bhardwaj Dr. | Priyanka Garg, Vinod Kumar Bhardwaj, Anirudh Pradhan | Barrow entropic Quintessence and Dilation dark energy Models with
Generalized HDE cut-off | 18 pages, 9 figures | International Journal of Modern Physics A, Vol. 37, No. 36 (2022)
2250217 (16 pages) | 10.1142/S0217751X22502177 | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | In the present work, we have analyzed the behaviors of extension of
generalized Barrow holographic dark energy(`BHDE'). A ``generalized BHDE model
based on the particle and the future horizon using infrared cut-off" was
proposed by Nojiri et al. (2022). In this work, we have reviewed the
generalized BHDE extension under the assumption of a generalized HDE cut-off.
Using a scale factor of the form $a = k t^m$, the dynamics of the cosmos have
been discussed through graphic demonstration. By applying the ``open-source
emcee Python package", the values of the free parameters $k$ and $m$ are
estimated on 57 OHD points by the Markov Chain Monte Carlo (MCMC) technique. We
have examined the behavior of the equation of state (EoS) parameter, $(
p_{de})$, and dark energy density $(\rho_{de})$. We have also discussed the
equivalence of holographic dark energy (DE) with the Barrow entropic DE and its
extension. Also, we have explained quintessence and dilation dark energy models
in the context of Barrow entropic DE.
| [
{
"created": "Sat, 18 Mar 2023 09:52:21 GMT",
"version": "v1"
}
] | 2023-03-21 | [
[
"Garg",
"Priyanka",
""
],
[
"Bhardwaj",
"Vinod Kumar",
""
],
[
"Pradhan",
"Anirudh",
""
]
] | In the present work, we have analyzed the behaviors of extension of generalized Barrow holographic dark energy(`BHDE'). A ``generalized BHDE model based on the particle and the future horizon using infrared cut-off" was proposed by Nojiri et al. (2022). In this work, we have reviewed the generalized BHDE extension under the assumption of a generalized HDE cut-off. Using a scale factor of the form $a = k t^m$, the dynamics of the cosmos have been discussed through graphic demonstration. By applying the ``open-source emcee Python package", the values of the free parameters $k$ and $m$ are estimated on 57 OHD points by the Markov Chain Monte Carlo (MCMC) technique. We have examined the behavior of the equation of state (EoS) parameter, $( p_{de})$, and dark energy density $(\rho_{de})$. We have also discussed the equivalence of holographic dark energy (DE) with the Barrow entropic DE and its extension. Also, we have explained quintessence and dilation dark energy models in the context of Barrow entropic DE. |
2103.15634 | Sebasti\'an G\'omez | M. Bravo-Gaete, C. G\'omez, L. Guajardo and S. G\'omez | Towards the emergence of non-zero thermodynamical quantities for
Lanczos-Lovelock black holes dressed with a scalar field | 10 pages, 3 figures | Phys. Rev. D 104, 044027 (2021) | 10.1103/PhysRevD.104.044027 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The present work aims to explore the model given by Lanczos-Lovelock gravity
theories indexed by a fixed integer to require a unique anti-de Sitter vacuum,
dressed by a scalar field non-minimal coupling. For this model, we add a
special matter source characterized by a non-linear Maxwell field coupling with
a function depending on the scalar field. Computing its thermodynamics
parameters by using the Euclidean action, we obtain interesting and non zero
thermodynamical quantities, unlike its original version, allowing analyzing
thermodynamical stability. Together with the above, we found that these
solutions satisfy the First Law of Thermodynamics as well as a Smarr relation.
| [
{
"created": "Mon, 29 Mar 2021 14:12:32 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Jul 2021 20:02:23 GMT",
"version": "v2"
}
] | 2021-08-18 | [
[
"Bravo-Gaete",
"M.",
""
],
[
"Gómez",
"C.",
""
],
[
"Guajardo",
"L.",
""
],
[
"Gómez",
"S.",
""
]
] | The present work aims to explore the model given by Lanczos-Lovelock gravity theories indexed by a fixed integer to require a unique anti-de Sitter vacuum, dressed by a scalar field non-minimal coupling. For this model, we add a special matter source characterized by a non-linear Maxwell field coupling with a function depending on the scalar field. Computing its thermodynamics parameters by using the Euclidean action, we obtain interesting and non zero thermodynamical quantities, unlike its original version, allowing analyzing thermodynamical stability. Together with the above, we found that these solutions satisfy the First Law of Thermodynamics as well as a Smarr relation. |
gr-qc/0005060 | Alicia M. Sintes | A.M. Sintes | Laser interferometer gravitational wave detectors | Latex, 4 pages. Published in "Relativity and Gravitation in general.
Proceedings of the Spanish Relativity Meeting in honour of the 65th birthday
of Lluis Bel". Edts. J. Martin, E. Ruiz, F.Atrio and A. Molina; World
Scientific, pp. 321-324 (1999) | null | null | null | gr-qc | null | I give a brief introduction on gravitational wave laser interferometers,
possible detectable sources from the ground and noise in the detectors
| [
{
"created": "Tue, 16 May 2000 12:37:31 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Sintes",
"A. M.",
""
]
] | I give a brief introduction on gravitational wave laser interferometers, possible detectable sources from the ground and noise in the detectors |
2309.07825 | Martin Bojowald | Luis Martinez, Martin Bojowald, Garrett Wendel | Freeze-free cosmological evolution with a non-monotonic internal clock | 24 pages, 4 figures | Phys. Rev. D 108 (2023) 086001 | 10.1103/PhysRevD.108.086001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Given the lack of an absolute time parameter in general relativistic systems,
quantum cosmology often describes the expansion of the universe in terms of
relational changes between two degrees of freedom, such as matter and geometry.
However, if clock degrees of freedom (self-)interact non-trivially, they in
general have turning points where their momenta vanish. At and beyond a turning
point, the evolution of other degrees of freedom is no longer described
directly by changes of the clock parameter because it stops and then turns
back, while time is moving forward. Previous attempts to describe quantum
evolution relative to a clock with turning points have failed and led to frozen
evolution in which degrees of freedom remain constant while the clock
parameter, interpreted directly as a substitute for monotonic time, is being
pushed beyond its turning point. Here, a new method previously used in
oscillator systems is applied to a tractable cosmological model, given by an
isotropic universe with spatial curvature and scalar matter. The re-collapsing
scale factor presents an example of a clock with a single turning point. The
method succeeds in defining unitary and freeze-free evolution by unwinding the
turning point of the clock, introducing an effective monotonic time parameter
that is related to but not identical with the non-monotonic clock degree of
freedom. Characteristic new quantum features are found around the turning
point, based on analytical and numerical calculations.
| [
{
"created": "Thu, 14 Sep 2023 16:18:10 GMT",
"version": "v1"
}
] | 2023-10-16 | [
[
"Martinez",
"Luis",
""
],
[
"Bojowald",
"Martin",
""
],
[
"Wendel",
"Garrett",
""
]
] | Given the lack of an absolute time parameter in general relativistic systems, quantum cosmology often describes the expansion of the universe in terms of relational changes between two degrees of freedom, such as matter and geometry. However, if clock degrees of freedom (self-)interact non-trivially, they in general have turning points where their momenta vanish. At and beyond a turning point, the evolution of other degrees of freedom is no longer described directly by changes of the clock parameter because it stops and then turns back, while time is moving forward. Previous attempts to describe quantum evolution relative to a clock with turning points have failed and led to frozen evolution in which degrees of freedom remain constant while the clock parameter, interpreted directly as a substitute for monotonic time, is being pushed beyond its turning point. Here, a new method previously used in oscillator systems is applied to a tractable cosmological model, given by an isotropic universe with spatial curvature and scalar matter. The re-collapsing scale factor presents an example of a clock with a single turning point. The method succeeds in defining unitary and freeze-free evolution by unwinding the turning point of the clock, introducing an effective monotonic time parameter that is related to but not identical with the non-monotonic clock degree of freedom. Characteristic new quantum features are found around the turning point, based on analytical and numerical calculations. |
1509.01695 | Gerard Hooft 't | Gerard t Hooft | Diagonalizing the Black Hole Information Retrieval Process | 10 pages, no figures | null | null | ITP-UU-15/12 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The mechanism by which black holes return the absorbed information to the
outside world is reconsidered, and described in terms of a set of mutually
non-interacting modes. Our mechanism is based on the mostly classical
gravitational back-reaction. The diagonalized formalism is particularly useful
for further studies of this process. Although no use is made of string theory,
our analysis appears to point towards an ensuing string-like interaction. It is
shown how black hole entropy can be traced down to classical gravitational
back-reaction.
| [
{
"created": "Sat, 5 Sep 2015 11:47:49 GMT",
"version": "v1"
}
] | 2015-09-08 | [
[
"Hooft",
"Gerard t",
""
]
] | The mechanism by which black holes return the absorbed information to the outside world is reconsidered, and described in terms of a set of mutually non-interacting modes. Our mechanism is based on the mostly classical gravitational back-reaction. The diagonalized formalism is particularly useful for further studies of this process. Although no use is made of string theory, our analysis appears to point towards an ensuing string-like interaction. It is shown how black hole entropy can be traced down to classical gravitational back-reaction. |
2404.10721 | Adailton Ara\'ujo Filho | A. A. Ara\'ujo Filho, N. Heidari, J. A. A. S. Reis, H. Hassanabadi | The impact of an antisymmetric tensor on charged black holes:
evaporation process, geodesics, deflection angle, scattering effects and
quasinormal modes | 44 pages, 17 figures, and 9 tables | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate the influence of anti-symmetric tensor effects,
which trigger the Lorentz symmetry breaking, on charged spherically symmetric
black holes. Initially, we address an overview of the model, laying the
groundwork for deriving solutions to black holes. With this, we analyze the
horizons, critical orbits, and geodesics. We compute quasinormal modes with a
particular emphasis on vectorial perturbations. In addition, we derive the
Hawking temperature to perform the calculation of the remnant mass.
Additionally, we estimate the lifetime of the black holes until they reach
their final stage after the evaporation process. Furthermore, we explore the
emission rate, and the deflection angle. Finally, we investigate the
correlation between quasinormal modes and shadows.
| [
{
"created": "Tue, 16 Apr 2024 16:54:00 GMT",
"version": "v1"
}
] | 2024-04-17 | [
[
"Filho",
"A. A. Araújo",
""
],
[
"Heidari",
"N.",
""
],
[
"Reis",
"J. A. A. S.",
""
],
[
"Hassanabadi",
"H.",
""
]
] | In this paper, we investigate the influence of anti-symmetric tensor effects, which trigger the Lorentz symmetry breaking, on charged spherically symmetric black holes. Initially, we address an overview of the model, laying the groundwork for deriving solutions to black holes. With this, we analyze the horizons, critical orbits, and geodesics. We compute quasinormal modes with a particular emphasis on vectorial perturbations. In addition, we derive the Hawking temperature to perform the calculation of the remnant mass. Additionally, we estimate the lifetime of the black holes until they reach their final stage after the evaporation process. Furthermore, we explore the emission rate, and the deflection angle. Finally, we investigate the correlation between quasinormal modes and shadows. |
0709.1933 | Victor Hamity H | V. H. Hamity, M. A. Cecere and D. E. Barraco | Relativistic dynamics of cylindrical shells of counter-rotating
particles | 19 pages, 8 figures | Gen.Rel.Grav.41:2657-2676,2009 | 10.1007/s10714-009-0794-x | null | gr-qc | null | Although infinite cylinders are not astrophysical entities, it is possible to
learn a great deal about the basic qualitative features of generation of
gravitational waves and the behavior of the matter conforming such shells in
the limits of very small radius. We describe the analytical model using kinetic
theory for the matter and the junction conditions through the shell to obtain
its equation of motion. The nature of the static solutions are analyzed, both
for a single shell as well as for two concentric shells. In this second case,
for a time dependent external shell, we integrate numerically the equation of
motion for several values of the constants of the system. Also, a brief
description in terms of the Komar mass is given to account for the
gravitational wave energy emitted by the system.
| [
{
"created": "Wed, 12 Sep 2007 17:22:24 GMT",
"version": "v1"
}
] | 2014-11-18 | [
[
"Hamity",
"V. H.",
""
],
[
"Cecere",
"M. A.",
""
],
[
"Barraco",
"D. E.",
""
]
] | Although infinite cylinders are not astrophysical entities, it is possible to learn a great deal about the basic qualitative features of generation of gravitational waves and the behavior of the matter conforming such shells in the limits of very small radius. We describe the analytical model using kinetic theory for the matter and the junction conditions through the shell to obtain its equation of motion. The nature of the static solutions are analyzed, both for a single shell as well as for two concentric shells. In this second case, for a time dependent external shell, we integrate numerically the equation of motion for several values of the constants of the system. Also, a brief description in terms of the Komar mass is given to account for the gravitational wave energy emitted by the system. |
1508.06701 | Juliano Neves | J. C. S. Neves | Deforming regular black holes | 9 pages, 4 figures. Version 3 matches the published version in IJMPA | Int. J. Mod. Phys. A 32, 1750112 (2017) | 10.1142/S0217751X17501123 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we have deformed regular black holes which possess a general
mass term described by a function which generalizes the Bardeen and Hayward
mass functions. By using linear constraints in the energy-momentum tensor to
generate metrics, the solutions presented in this work are either regular or
singular. That is, within this approach, it is possible to generate regular or
singular black holes from regular or singular black holes. Moreover, contrary
to the Bardeen and Hayward regular solutions, the deformed regular black holes
may violate the weak energy condition despite the presence of the spherical
symmetry. Some comments on accretion of deformed black holes in cosmological
scenarios are made.
| [
{
"created": "Thu, 27 Aug 2015 02:12:57 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Aug 2016 19:07:36 GMT",
"version": "v2"
},
{
"created": "Wed, 28 Jun 2017 15:27:27 GMT",
"version": "v3"
}
] | 2017-06-29 | [
[
"Neves",
"J. C. S.",
""
]
] | In this work we have deformed regular black holes which possess a general mass term described by a function which generalizes the Bardeen and Hayward mass functions. By using linear constraints in the energy-momentum tensor to generate metrics, the solutions presented in this work are either regular or singular. That is, within this approach, it is possible to generate regular or singular black holes from regular or singular black holes. Moreover, contrary to the Bardeen and Hayward regular solutions, the deformed regular black holes may violate the weak energy condition despite the presence of the spherical symmetry. Some comments on accretion of deformed black holes in cosmological scenarios are made. |
gr-qc/0503001 | Carlos O. Lousto | Carlos O. Lousto (UT Brownsville) | A time-domain fourth-order-convergent numerical algorithm to integrate
black hole perturbations in the extreme-mass-ratio limit | 30 pages, 12 figures | Class.Quant.Grav. 22 (2005) S543-S568 | 10.1088/0264-9381/22/15/001 | null | gr-qc | null | We obtain a fourth order accurate numerical algorithm to integrate the
Zerilli and Regge-Wheeler wave equations, describing perturbations of
nonrotating black holes, with source terms due to an orbiting particle. Those
source terms contain the Dirac's delta and its first derivative. We also
re-derive the source of the Zerilli and Regge-Wheeler equations for more
convenient definitions of the waveforms, that allow direct metric
reconstruction (in the Regge-Wheeler gauge).
| [
{
"created": "Mon, 28 Feb 2005 23:46:49 GMT",
"version": "v1"
},
{
"created": "Mon, 8 Aug 2005 19:47:53 GMT",
"version": "v2"
},
{
"created": "Fri, 26 May 2006 23:16:44 GMT",
"version": "v3"
}
] | 2009-11-11 | [
[
"Lousto",
"Carlos O.",
"",
"UT Brownsville"
]
] | We obtain a fourth order accurate numerical algorithm to integrate the Zerilli and Regge-Wheeler wave equations, describing perturbations of nonrotating black holes, with source terms due to an orbiting particle. Those source terms contain the Dirac's delta and its first derivative. We also re-derive the source of the Zerilli and Regge-Wheeler equations for more convenient definitions of the waveforms, that allow direct metric reconstruction (in the Regge-Wheeler gauge). |
1006.5666 | Etera R. Livine | Mait\'e Dupuis, Etera R. Livine | Revisiting the Simplicity Constraints and Coherent Intertwiners | 28 pages | Class.Quant.Grav.28:085001,2011 | 10.1088/0264-9381/28/8/085001 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the context of loop quantum gravity and spinfoam models, the simplicity
constraints are essential in that they allow to write general relativity as a
constrained topological BF theory. In this work, we apply the recently
developed U(N) framework for SU(2) intertwiners to the issue of imposing the
simplicity constraints to spin network states. More particularly, we focus on
solving them on individual intertwiners in the 4d Euclidean theory. We review
the standard way of solving the simplicity constraints using coherent
intertwiners and we explain how these fit within the U(N) framework. Then we
show how these constraints can be written as a closed u(N) algebra and we
propose a set of U(N) coherent states that solves all the simplicity
constraints weakly for an arbitrary Immirzi parameter.
| [
{
"created": "Tue, 29 Jun 2010 16:18:35 GMT",
"version": "v1"
}
] | 2011-03-17 | [
[
"Dupuis",
"Maité",
""
],
[
"Livine",
"Etera R.",
""
]
] | In the context of loop quantum gravity and spinfoam models, the simplicity constraints are essential in that they allow to write general relativity as a constrained topological BF theory. In this work, we apply the recently developed U(N) framework for SU(2) intertwiners to the issue of imposing the simplicity constraints to spin network states. More particularly, we focus on solving them on individual intertwiners in the 4d Euclidean theory. We review the standard way of solving the simplicity constraints using coherent intertwiners and we explain how these fit within the U(N) framework. Then we show how these constraints can be written as a closed u(N) algebra and we propose a set of U(N) coherent states that solves all the simplicity constraints weakly for an arbitrary Immirzi parameter. |
0808.0107 | S Habib Mazharimousavi | S. Habib Mazharimousavi, I. Sakalli and M. Halilsoy | Hawking radiation for higher dimensional Einstein-Yang-Mills linear
dilaton black holes | 9 pages, 2 figures, | Physics Letters B 672 (2009) 177 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, Hawking radiation from a $4-$dimensional linear dilaton black hole
solution to Einstein-Maxwell-Dilaton (EMD) theory, via a method of computing
exactly the semi-classical radiation, has been derived by Cl\U{e9}ment, et al.
Their results show that, whenever solution is available to the massless scalar
wave equation, an exact computation of the radiation spectrum leads to the
Hawking temperature $T_{H}$. We apply the same method to derive Hawking
radiation spectrum for higher dimensional linear dilaton black holes in the
Einstein-Yang-Mills-Dilaton (EYMD) and Einstein-Maxwell-Dilaton (EMD) theories.
Our results show that the radiation with high frequencies for these massive
black holes reveal some remarkable information about the $T_{H}$.
| [
{
"created": "Fri, 1 Aug 2008 12:28:20 GMT",
"version": "v1"
}
] | 2009-02-09 | [
[
"Mazharimousavi",
"S. Habib",
""
],
[
"Sakalli",
"I.",
""
],
[
"Halilsoy",
"M.",
""
]
] | Recently, Hawking radiation from a $4-$dimensional linear dilaton black hole solution to Einstein-Maxwell-Dilaton (EMD) theory, via a method of computing exactly the semi-classical radiation, has been derived by Cl\U{e9}ment, et al. Their results show that, whenever solution is available to the massless scalar wave equation, an exact computation of the radiation spectrum leads to the Hawking temperature $T_{H}$. We apply the same method to derive Hawking radiation spectrum for higher dimensional linear dilaton black holes in the Einstein-Yang-Mills-Dilaton (EYMD) and Einstein-Maxwell-Dilaton (EMD) theories. Our results show that the radiation with high frequencies for these massive black holes reveal some remarkable information about the $T_{H}$. |
gr-qc/9604019 | Carsten Gundlach | Carsten Gundlach | Understanding critical collapse of a scalar field | RevTex, 26 galley or 53 preprint pages, 3 EPS figures, 2 tables | Phys.Rev. D55 (1997) 695-713 | 10.1103/PhysRevD.55.695 | LAEFF-96/07 | gr-qc | null | I construct a spherically symmetric solution for a massless real scalar field
minimally coupled to general relativity which is discretely self-similar (DSS)
and regular. This solution coincides with the intermediate attractor found by
Choptuik in critical gravitational collapse. The echoing period is Delta =
3.4453 +/- 0.0005. The solution is continued to the future self-similarity
horizon, which is also the future light cone of a naked singularity. The scalar
field and metric are C1 but not C2 at this Cauchy horizon. The curvature is
finite nevertheless, and the horizon carries regular null data. These are very
nearly flat. The solution has exactly one growing perturbation mode, thus
confirming the standard explanation for universality. The growth of this mode
corresponds to a critical exponent of gamma = 0.374 +/- 0.001, in agreement
with the best experimental value. I predict that in critical collapse dominated
by a DSS critical solution, the scaling of the black hole mass shows a periodic
wiggle, which like gamma is universal. My results carry over to the free
complex scalar field. Connections with previous investigations of self-similar
scalar field solutions are discussed, as well as an interpretation of Delta and
gamma as anomalous dimensions.
| [
{
"created": "Mon, 8 Apr 1996 16:36:52 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Gundlach",
"Carsten",
""
]
] | I construct a spherically symmetric solution for a massless real scalar field minimally coupled to general relativity which is discretely self-similar (DSS) and regular. This solution coincides with the intermediate attractor found by Choptuik in critical gravitational collapse. The echoing period is Delta = 3.4453 +/- 0.0005. The solution is continued to the future self-similarity horizon, which is also the future light cone of a naked singularity. The scalar field and metric are C1 but not C2 at this Cauchy horizon. The curvature is finite nevertheless, and the horizon carries regular null data. These are very nearly flat. The solution has exactly one growing perturbation mode, thus confirming the standard explanation for universality. The growth of this mode corresponds to a critical exponent of gamma = 0.374 +/- 0.001, in agreement with the best experimental value. I predict that in critical collapse dominated by a DSS critical solution, the scaling of the black hole mass shows a periodic wiggle, which like gamma is universal. My results carry over to the free complex scalar field. Connections with previous investigations of self-similar scalar field solutions are discussed, as well as an interpretation of Delta and gamma as anomalous dimensions. |
gr-qc/0702137 | Hakan Andreasson | Hakan Andreasson | Sharp bounds on $2m/r$ of general spherically symmetric static objects | 28 pages, typos corrected and the analogy in section 4 is presented
slightly differently | J. Diff. Eq. 245:2243-2266,2008 | 10.1016/j.jde.2008.05.010 | null | gr-qc | null | In 1959 Buchdahl \cite{Bu} obtained the inequality $2M/R\leq 8/9$ under the
assumptions that the energy density is non-increasing outwards and that the
pressure is isotropic. Here $M$ is the ADM mass and $R$ the area radius of the
boundary of the static body. The assumptions used to derive the Buchdahl
inequality are very restrictive and e.g. neither of them hold in a simple soap
bubble. In this work we remove both of these assumptions and consider
\textit{any} static solution of the spherically symmetric Einstein equations
for which the energy density $\rho\geq 0,$ and the radial- and tangential
pressures $p\geq 0$ and $p_T,$ satisfy $p+2p_T\leq\Omega\rho, \Omega>0,$ and we
show that $$\sup_{r>0}\frac{2m(r)}{r}\leq
\frac{(1+2\Omega)^2-1}{(1+2\Omega)^2},$$ where $m$ is the quasi-local mass, so
that in particular $M=m(R).$ We also show that the inequality is sharp. Note
that when $\Omega=1$ the original bound by Buchdahl is recovered. The
assumptions on the matter model are very general and in particular any model
with $p\geq 0$ which satisfies the dominant energy condition satisfies the
hypotheses with $\Omega=3.$
| [
{
"created": "Mon, 26 Feb 2007 13:48:38 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Mar 2007 16:16:51 GMT",
"version": "v2"
}
] | 2011-08-31 | [
[
"Andreasson",
"Hakan",
""
]
] | In 1959 Buchdahl \cite{Bu} obtained the inequality $2M/R\leq 8/9$ under the assumptions that the energy density is non-increasing outwards and that the pressure is isotropic. Here $M$ is the ADM mass and $R$ the area radius of the boundary of the static body. The assumptions used to derive the Buchdahl inequality are very restrictive and e.g. neither of them hold in a simple soap bubble. In this work we remove both of these assumptions and consider \textit{any} static solution of the spherically symmetric Einstein equations for which the energy density $\rho\geq 0,$ and the radial- and tangential pressures $p\geq 0$ and $p_T,$ satisfy $p+2p_T\leq\Omega\rho, \Omega>0,$ and we show that $$\sup_{r>0}\frac{2m(r)}{r}\leq \frac{(1+2\Omega)^2-1}{(1+2\Omega)^2},$$ where $m$ is the quasi-local mass, so that in particular $M=m(R).$ We also show that the inequality is sharp. Note that when $\Omega=1$ the original bound by Buchdahl is recovered. The assumptions on the matter model are very general and in particular any model with $p\geq 0$ which satisfies the dominant energy condition satisfies the hypotheses with $\Omega=3.$ |
1401.3155 | Wolung Lee | Wenjie Lu, Wolung Lee and Kin-Wang Ng | Teleparallel Poincar\'{e} Cosmology and $\Lambda$CDM Model | 7 pages by revtex4.1, no figure | IJMPD 23(2014)1450057 | 10.1142/S0218271814500576 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We apply the teleparallelism condition to the Poincar\'{e} gauge theory of
gravity. The resultant teleparallelized cosmology is completely equivalent to
the Friedmann cosmology derived from Einstein's general theory of relativity.
The torsion is shown to play the role of the cosmological constant driving the
cosmic acceleration. We then extend such theory to include the effect of spin
and explore the possibility of accounting for the current accelerating universe
by a spinning dark energy.
| [
{
"created": "Tue, 14 Jan 2014 11:56:14 GMT",
"version": "v1"
}
] | 2014-09-10 | [
[
"Lu",
"Wenjie",
""
],
[
"Lee",
"Wolung",
""
],
[
"Ng",
"Kin-Wang",
""
]
] | We apply the teleparallelism condition to the Poincar\'{e} gauge theory of gravity. The resultant teleparallelized cosmology is completely equivalent to the Friedmann cosmology derived from Einstein's general theory of relativity. The torsion is shown to play the role of the cosmological constant driving the cosmic acceleration. We then extend such theory to include the effect of spin and explore the possibility of accounting for the current accelerating universe by a spinning dark energy. |
2210.09861 | Yuewen Chen | Yuewen Chen, Shing-Tung Yau | Stable regular solution of Einstein-Yang-Mills equation | null | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this letter, we find the first dynamically stable non-singular solution
spherically symmetric SU(2) Einstein-Yang-Mills equation. This solutions is
regular at r=0 and asymptotically flat. Since the Yang-Mills field strength
decay exponentially, the Einstein-Yang-Mills particle perhaps can be used to be
a candidate for dark matter.
| [
{
"created": "Tue, 18 Oct 2022 13:48:30 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Oct 2022 16:35:07 GMT",
"version": "v2"
},
{
"created": "Sun, 30 Oct 2022 13:12:05 GMT",
"version": "v3"
}
] | 2022-11-01 | [
[
"Chen",
"Yuewen",
""
],
[
"Yau",
"Shing-Tung",
""
]
] | In this letter, we find the first dynamically stable non-singular solution spherically symmetric SU(2) Einstein-Yang-Mills equation. This solutions is regular at r=0 and asymptotically flat. Since the Yang-Mills field strength decay exponentially, the Einstein-Yang-Mills particle perhaps can be used to be a candidate for dark matter. |
1808.00317 | Paul Tod | Paul Tod | An example of an asymptotically $AdS_2\times S^2$ metric satisfying NEC
but which is not exactly $AdS_2\times S^2$ | 8 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give an example of an asymptotically $AdS_2\times S^2$ metric, in the
sense of \cite{GG}, which satisfies the Null Energy Condition but is not
exactly $AdS_2\times S^2$. It is therefore a counterexample to a conjecture of
Maldacena mentioned in \cite{GG}, but it does not satisfy field equations. In
an appendix we give an example admitting supercovariantly constant spinors as
in \cite{t1}, which is asymptotically $AdS_2\times S^2$ on one side only.
| [
{
"created": "Wed, 1 Aug 2018 13:47:29 GMT",
"version": "v1"
}
] | 2018-08-02 | [
[
"Tod",
"Paul",
""
]
] | We give an example of an asymptotically $AdS_2\times S^2$ metric, in the sense of \cite{GG}, which satisfies the Null Energy Condition but is not exactly $AdS_2\times S^2$. It is therefore a counterexample to a conjecture of Maldacena mentioned in \cite{GG}, but it does not satisfy field equations. In an appendix we give an example admitting supercovariantly constant spinors as in \cite{t1}, which is asymptotically $AdS_2\times S^2$ on one side only. |
gr-qc/9905107 | Sardanashvily Gennadi | L.Mangiarotti, G.Sardanashvily | Nonrelativistic Geodesic Motion | 17 pages, LaTeX | null | null | null | gr-qc | null | We show that any second order dynamic equation on a configuration space $X\to
R$ of nonrelativistic mechanics can be seen as a geodesic equation with respect
to some (nonlinear) connection on the tangent bundle $TX\to X$ of relativistic
velocities. We compare relativistic and nonrelativistic geodesic equations, and
study the Jacobi vector fields along nonrelativistic geodesics.
| [
{
"created": "Mon, 31 May 1999 06:31:53 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Mangiarotti",
"L.",
""
],
[
"Sardanashvily",
"G.",
""
]
] | We show that any second order dynamic equation on a configuration space $X\to R$ of nonrelativistic mechanics can be seen as a geodesic equation with respect to some (nonlinear) connection on the tangent bundle $TX\to X$ of relativistic velocities. We compare relativistic and nonrelativistic geodesic equations, and study the Jacobi vector fields along nonrelativistic geodesics. |
gr-qc/0005094 | Joseph Samuel | Joseph Samuel | Canonical Gravity, Diffeomorphisms and Objective Histories | Latex 16 Pages, no figures, revised in the light of referees'
comments, accepted for publication in Classical and Quantum Gravity | Class.Quant.Grav. 17 (2000) 4645-4654 | 10.1088/0264-9381/17/22/305 | null | gr-qc | null | This paper discusses the implementation of diffeomorphism invariance in
purely Hamiltonian formulations of General Relativity. We observe that, if a
constrained Hamiltonian formulation derives from a manifestly covariant
Lagrangian, the diffeomorphism invariance of the Lagrangian results in the
following properties of the constrained Hamiltonian theory: the diffeomorphisms
are generated by constraints on the phase space so that a) The algebra of the
generators reflects the algebra of the diffeomorphism group. b) The Poisson
brackets of the basic fields with the generators reflects the space-time
transformation properties of these basic fields. This suggests that in a purely
Hamiltonian approach the requirement of diffeomorphism invariance should be
interpreted to include b) and not just a) as one might naively suppose. Giving
up b) amounts to giving up objective histories, even at the classical level.
This observation has implications for Loop Quantum Gravity which are spelled
out in a companion paper. We also describe an analogy between canonical gravity
and Relativistic particle dynamics to illustrate our main point.
| [
{
"created": "Mon, 22 May 2000 07:54:12 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Sep 2000 12:23:43 GMT",
"version": "v2"
},
{
"created": "Wed, 20 Sep 2000 10:46:16 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Samuel",
"Joseph",
""
]
] | This paper discusses the implementation of diffeomorphism invariance in purely Hamiltonian formulations of General Relativity. We observe that, if a constrained Hamiltonian formulation derives from a manifestly covariant Lagrangian, the diffeomorphism invariance of the Lagrangian results in the following properties of the constrained Hamiltonian theory: the diffeomorphisms are generated by constraints on the phase space so that a) The algebra of the generators reflects the algebra of the diffeomorphism group. b) The Poisson brackets of the basic fields with the generators reflects the space-time transformation properties of these basic fields. This suggests that in a purely Hamiltonian approach the requirement of diffeomorphism invariance should be interpreted to include b) and not just a) as one might naively suppose. Giving up b) amounts to giving up objective histories, even at the classical level. This observation has implications for Loop Quantum Gravity which are spelled out in a companion paper. We also describe an analogy between canonical gravity and Relativistic particle dynamics to illustrate our main point. |
gr-qc/0405102 | Filipe Mena | Paul Tod (Oxford) and Filipe C. Mena (Oxford/Minho) | Matching of spatially homogeneous non-stationary space--times to vacuum
in cylindrical symmetry | LaTeX, 15 pages, 1 figure, submitted for publication | Phys.Rev.D70:104028,2004 | 10.1103/PhysRevD.70.104028 | null | gr-qc | null | We study the matching of LRS spatially homogeneous collapsing dust
space-times with non-stationary vacuum exteriors in cylindrical symmetry. Given
an interior with diagonal metric we prove existence and uniqueness results for
the exterior. The matched solutions contain trapped surfaces, singularities and
Cauchy horizons. The solutions cannot be asymptotically flat and we present
evidence that they are singular on the Cauchy horizons.
| [
{
"created": "Tue, 18 May 2004 22:22:08 GMT",
"version": "v1"
}
] | 2011-08-12 | [
[
"Tod",
"Paul",
"",
"Oxford"
],
[
"Mena",
"Filipe C.",
"",
"Oxford/Minho"
]
] | We study the matching of LRS spatially homogeneous collapsing dust space-times with non-stationary vacuum exteriors in cylindrical symmetry. Given an interior with diagonal metric we prove existence and uniqueness results for the exterior. The matched solutions contain trapped surfaces, singularities and Cauchy horizons. The solutions cannot be asymptotically flat and we present evidence that they are singular on the Cauchy horizons. |
1311.3275 | Peter K.F. Kuhfittig | Peter K.F. Kuhfittig | A note on wormholes in slightly modified gravitational theories | 4 pages, no figures | Adv. Studies Theor. Phys., vol. 7, 1087-1093 (2013) | 10.12988/astp.2013.3998 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Wormholes that meet the flare-out condition violate the weak energy condition
in classical general relativity. The purpose of this note is to show that even
a slight modification of the gravitational theory could, under certain
conditions, avoid this violation for matter threading the wormhole. The first
part discusses some general criteria based on the field equations, while the
second part assumes a specific equation of state describing normal matter,
together with a particular type of shape function. The analysis is confined to
wormholes with zero tidal forces.
| [
{
"created": "Wed, 13 Nov 2013 20:05:44 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Dec 2013 17:52:03 GMT",
"version": "v2"
},
{
"created": "Thu, 2 Feb 2017 16:20:28 GMT",
"version": "v3"
}
] | 2017-02-03 | [
[
"Kuhfittig",
"Peter K. F.",
""
]
] | Wormholes that meet the flare-out condition violate the weak energy condition in classical general relativity. The purpose of this note is to show that even a slight modification of the gravitational theory could, under certain conditions, avoid this violation for matter threading the wormhole. The first part discusses some general criteria based on the field equations, while the second part assumes a specific equation of state describing normal matter, together with a particular type of shape function. The analysis is confined to wormholes with zero tidal forces. |
0811.3952 | Ulrich Sperhake | Jose A. Gonzalez, Ulrich Sperhake, Bernd Bruegmann | Black-hole binary simulations: the mass ratio 10:1 | To match published version | Phys.Rev.D79:124006,2009 | 10.1103/PhysRevD.79.124006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the first numerical simulations of an initially non-spinning
black-hole binary with mass ratio as large as 10:1 in full general relativity.
The binary completes approximately 3 orbits prior to merger and radiates about
0.415% of the total energy and 12.48% of the initial angular momentum in the
form of gravitational waves. The single black hole resulting from the merger
acquires a kick of about 66.7 km/s relative to the original center of mass
frame. The resulting gravitational waveforms are used to validate existing
formulas for the recoil, final spin and radiated energy over a wider range of
the symmetric mass ratio parameter eta=M1*M2/(M1+M2)^2 than previously
possible. The contributions of l > 2 multipoles are found to visibly influence
the gravitational wave signal obtained at fixed inclination angles.
| [
{
"created": "Mon, 24 Nov 2008 20:51:26 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Aug 2009 02:49:59 GMT",
"version": "v2"
}
] | 2010-03-26 | [
[
"Gonzalez",
"Jose A.",
""
],
[
"Sperhake",
"Ulrich",
""
],
[
"Bruegmann",
"Bernd",
""
]
] | We present the first numerical simulations of an initially non-spinning black-hole binary with mass ratio as large as 10:1 in full general relativity. The binary completes approximately 3 orbits prior to merger and radiates about 0.415% of the total energy and 12.48% of the initial angular momentum in the form of gravitational waves. The single black hole resulting from the merger acquires a kick of about 66.7 km/s relative to the original center of mass frame. The resulting gravitational waveforms are used to validate existing formulas for the recoil, final spin and radiated energy over a wider range of the symmetric mass ratio parameter eta=M1*M2/(M1+M2)^2 than previously possible. The contributions of l > 2 multipoles are found to visibly influence the gravitational wave signal obtained at fixed inclination angles. |
2311.12930 | Marco Calz\`a | Marco Calz\`a, Jo\~ao G.Rosa | Determining the spin of light primordial black holes with Hawking
radiation II: high spin regime | null | null | null | null | gr-qc astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a method to determine the mass and spin of primordial black holes
based on measuring the energy and emission rate at the dipolar and quadrupolar
peaks in the primary photon Hawking spectrum, applicable for dimensionless spin
parameters $\tilde{a}\gtrsim 0.6$. In particular, we show that the ratio
between the energies of the two peaks is only a function of the black hole
spin, while the ratio between their emission rates depends also on the
line-of-sight inclination. The black hole mass and distance from the Earth may
then be inferred from the absolute values of the peak energies and emission
rates. This method is relevant for primordial black holes born with large spin
parameters that are presently still in the early stages of their evaporation
process.
| [
{
"created": "Tue, 21 Nov 2023 19:00:05 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Dec 2023 17:06:58 GMT",
"version": "v2"
}
] | 2023-12-05 | [
[
"Calzà",
"Marco",
""
],
[
"Rosa",
"João G.",
""
]
] | We propose a method to determine the mass and spin of primordial black holes based on measuring the energy and emission rate at the dipolar and quadrupolar peaks in the primary photon Hawking spectrum, applicable for dimensionless spin parameters $\tilde{a}\gtrsim 0.6$. In particular, we show that the ratio between the energies of the two peaks is only a function of the black hole spin, while the ratio between their emission rates depends also on the line-of-sight inclination. The black hole mass and distance from the Earth may then be inferred from the absolute values of the peak energies and emission rates. This method is relevant for primordial black holes born with large spin parameters that are presently still in the early stages of their evaporation process. |
1510.02347 | Mohsen Fathi | Mohsen Fathi, Morteza Mohseni | Surface configuration in $R + {\mu}^4/R$ gravity | 10 pages, 9 figures | Mod. Phys. Lett. A, Vol. 30, No. 33 (2015) 1550171 | 10.1142/S0217732315501710 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the conditions on the additional constant $\mu$ in the
so-called $R+\mu^4/R$ theory of gravity, due to existence of different kinds of
space-like surfaces in both weak field and strong field limits, and their
possible correspondence to black hole event horizons. Adopting a Schwarzschild
limit, we probe the behaviour of $\mu$ in different contexts of radial and
radial-rotational congruence of null geodesics. We show that these cases serve
as correspondents to black hole horizons in some peculiar cases of study.
| [
{
"created": "Wed, 7 Oct 2015 04:54:49 GMT",
"version": "v1"
}
] | 2015-10-09 | [
[
"Fathi",
"Mohsen",
""
],
[
"Mohseni",
"Morteza",
""
]
] | We investigate the conditions on the additional constant $\mu$ in the so-called $R+\mu^4/R$ theory of gravity, due to existence of different kinds of space-like surfaces in both weak field and strong field limits, and their possible correspondence to black hole event horizons. Adopting a Schwarzschild limit, we probe the behaviour of $\mu$ in different contexts of radial and radial-rotational congruence of null geodesics. We show that these cases serve as correspondents to black hole horizons in some peculiar cases of study. |
1712.09106 | Lorenzo Iorio | Lorenzo Iorio | Perspectives on constraining a cosmological constant-type parameter with
pulsar timing in the Galactic Center | Latex2e, 12 pages, 1 table, 1 figure, 79 references | Universe (2018) 4: 59 | 10.3390/universe4040059 | null | gr-qc astro-ph.GA physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Independent tests aiming to constrain the value of the cosmological constant
$\Lambda$ are usually difficult because of its extreme smallness $\left(\Lambda
\simeq 1\times 10^{-52}~\textrm{m}^{-2},~\textrm{or}~2.89\times
10^{-122}~\textrm{in Planck units}\right)$. Bounds on it from Solar System
orbital motions determined with spacecraft tracking are currently at the
$\simeq 10^{-43}-10^{-44}~\textrm{m}^{-2}~\left(5-1\times 10^{-113}~\textrm{in
Planck units}\right)$ level, but they may turn out to be somewhat optimistic
since $\Lambda$ has not yet been explicitly modeled in the planetary data
reductions. Accurate $\left(\sigma_{\tau_\textrm{p}}\simeq
1-10~\mu\textrm{s}\right)$ timing of expected pulsars orbiting the Black Hole
at the Galactic Center, preferably along highly eccentric and wide orbits,
might, at least in principle, improve the planetary constraints by several
orders of magnitude. By looking at the average time shift per orbit
$\overline{\Delta\delta\tau}^\Lambda_\textrm{p}$, a S2-like orbital
configuration with $e=0.8839,~P_\textrm{b}=16~\textrm{yr}$ would allow to
obtain preliminarily an upper bound of the order of
$\left|\Lambda\right|\lesssim 9\times 10^{-47}~\textrm{m}^{-2}~\left(\lesssim
2\times 10^{-116}~\textrm{in Planck units}\right)$ if only
$\sigma_{\tau_\textrm{p}}$ were to be considered. Our results can be easily
extended to modified models of gravity using $\Lambda-$type parameters.
| [
{
"created": "Mon, 25 Dec 2017 17:42:38 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Dec 2017 10:23:03 GMT",
"version": "v2"
},
{
"created": "Mon, 26 Mar 2018 18:18:16 GMT",
"version": "v3"
}
] | 2018-03-28 | [
[
"Iorio",
"Lorenzo",
""
]
] | Independent tests aiming to constrain the value of the cosmological constant $\Lambda$ are usually difficult because of its extreme smallness $\left(\Lambda \simeq 1\times 10^{-52}~\textrm{m}^{-2},~\textrm{or}~2.89\times 10^{-122}~\textrm{in Planck units}\right)$. Bounds on it from Solar System orbital motions determined with spacecraft tracking are currently at the $\simeq 10^{-43}-10^{-44}~\textrm{m}^{-2}~\left(5-1\times 10^{-113}~\textrm{in Planck units}\right)$ level, but they may turn out to be somewhat optimistic since $\Lambda$ has not yet been explicitly modeled in the planetary data reductions. Accurate $\left(\sigma_{\tau_\textrm{p}}\simeq 1-10~\mu\textrm{s}\right)$ timing of expected pulsars orbiting the Black Hole at the Galactic Center, preferably along highly eccentric and wide orbits, might, at least in principle, improve the planetary constraints by several orders of magnitude. By looking at the average time shift per orbit $\overline{\Delta\delta\tau}^\Lambda_\textrm{p}$, a S2-like orbital configuration with $e=0.8839,~P_\textrm{b}=16~\textrm{yr}$ would allow to obtain preliminarily an upper bound of the order of $\left|\Lambda\right|\lesssim 9\times 10^{-47}~\textrm{m}^{-2}~\left(\lesssim 2\times 10^{-116}~\textrm{in Planck units}\right)$ if only $\sigma_{\tau_\textrm{p}}$ were to be considered. Our results can be easily extended to modified models of gravity using $\Lambda-$type parameters. |
2207.11023 | Andronikos Paliathanasis | Andronikos Paliathanasis | Cosmological solutions with time-delay | 18 pages, 3 figures, to appear in MPLA | null | 10.1142/S021773232250167X | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | We introduce a time-delay function in bulk viscosity cosmology. Even for bulk
viscosity functions where closed-form solutions are known, because of the
time-delay term the exact solutions are lost. Therefore in order to study the
cosmological evolution of the resulting models we perform a detail analysis of
the stability of the critical points, which describe de Sitter solutions, by
using Lindstedt's method. We find that for the stability of the critical points
it depends also on the time-delay parameter, where a critical time-delay value
is found which play the role of a bifurcation point. For time-delay values near
to the critical value, the cosmological evolution has a periodic evolution,
this oscillating behaviour is because of the time-delay function. We find a new
behaviour near the exponential expansion point, which can be seen also as an
alternative way to exit the exponential inflation.
| [
{
"created": "Fri, 22 Jul 2022 11:55:09 GMT",
"version": "v1"
}
] | 2022-11-23 | [
[
"Paliathanasis",
"Andronikos",
""
]
] | We introduce a time-delay function in bulk viscosity cosmology. Even for bulk viscosity functions where closed-form solutions are known, because of the time-delay term the exact solutions are lost. Therefore in order to study the cosmological evolution of the resulting models we perform a detail analysis of the stability of the critical points, which describe de Sitter solutions, by using Lindstedt's method. We find that for the stability of the critical points it depends also on the time-delay parameter, where a critical time-delay value is found which play the role of a bifurcation point. For time-delay values near to the critical value, the cosmological evolution has a periodic evolution, this oscillating behaviour is because of the time-delay function. We find a new behaviour near the exponential expansion point, which can be seen also as an alternative way to exit the exponential inflation. |
2401.15342 | Junji Jia | Shaofei Xu, Junji Jia | Dragging of the particle spin and spin-spin coupling effect on its
periapsis shift | 7 pages, 2 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The periapsis shift (PS) of spinning test particles in the equatorial plane
of arbitrary stationary and axisymmetric spacetime is studied using the
post-Newtonian method. The result is expressed as a half-integer power series
of $M/p$ where $M$ is the spacetime mass and $p$ is the semilatus rectum. The
coefficients of the series are polynomials of the particle spin, the asymptotic
expansion coefficients of the metric functions and the eccentricity of the
orbit. The particle spin is shown to have a similar effect as the
Lense-Thirring (LT) effect on the PS, and both of them appear from the
$(M/p)^{-3/2}$ order in the PS. The coupling between the spacetime and particle
spins will increase (or decrease) the PS if they are parallel (or
antiparallel). For Jupiter and Saturn rotating around the Sun and exceptionally
designed satellites around Mercury and Moon, the particle spin effect can be
comparable to the LT one in size. The PS in other spacetime studied are not
distinguishable from that in the Kerr spacetime to the $(M/p)^{-3/2}$ order.
| [
{
"created": "Sat, 27 Jan 2024 08:20:55 GMT",
"version": "v1"
}
] | 2024-01-30 | [
[
"Xu",
"Shaofei",
""
],
[
"Jia",
"Junji",
""
]
] | The periapsis shift (PS) of spinning test particles in the equatorial plane of arbitrary stationary and axisymmetric spacetime is studied using the post-Newtonian method. The result is expressed as a half-integer power series of $M/p$ where $M$ is the spacetime mass and $p$ is the semilatus rectum. The coefficients of the series are polynomials of the particle spin, the asymptotic expansion coefficients of the metric functions and the eccentricity of the orbit. The particle spin is shown to have a similar effect as the Lense-Thirring (LT) effect on the PS, and both of them appear from the $(M/p)^{-3/2}$ order in the PS. The coupling between the spacetime and particle spins will increase (or decrease) the PS if they are parallel (or antiparallel). For Jupiter and Saturn rotating around the Sun and exceptionally designed satellites around Mercury and Moon, the particle spin effect can be comparable to the LT one in size. The PS in other spacetime studied are not distinguishable from that in the Kerr spacetime to the $(M/p)^{-3/2}$ order. |
2101.06442 | Eugen Radu | C. A. R. Herdeiro, J. Kunz, I. Perapechka, E. Radu and Y. Shnir | Chains of Boson Stars | 20 pages, 6 figures | Phys. Rev. D 103, 065009 (2021) | 10.1103/PhysRevD.103.065009 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We study axially symmetric multi-soliton solutions of a complex scalar field
theory with a sextic potential, minimally coupled to Einstein's gravity. These
solutions carry no angular momentum and can be classified by the number of
nodes of the scalar field, $k_z$, along the symmetry axis; they are interpreted
as chains with $k_z+1$ boson stars, bound by gravity, but kept apart by
repulsive scalar interactions. Chains with an odd number of constituents show a
spiraling behavior for their ADM mass (and Noether charge) in terms of their
angular frequency, similarly to a single fundamental boson star, as long as the
gravitational coupling is small; for larger coupling, however, the inner part
of the spiral is replaced by a merging with the fundamental branch of radially
excited spherical boson stars. Chains with an even number of constituents
exhibit a truncated spiral pattern, with only two or three branches, ending at
a limiting solution with finite values of ADM mass and Noether charge.
| [
{
"created": "Sat, 16 Jan 2021 12:34:00 GMT",
"version": "v1"
}
] | 2021-03-31 | [
[
"Herdeiro",
"C. A. R.",
""
],
[
"Kunz",
"J.",
""
],
[
"Perapechka",
"I.",
""
],
[
"Radu",
"E.",
""
],
[
"Shnir",
"Y.",
""
]
] | We study axially symmetric multi-soliton solutions of a complex scalar field theory with a sextic potential, minimally coupled to Einstein's gravity. These solutions carry no angular momentum and can be classified by the number of nodes of the scalar field, $k_z$, along the symmetry axis; they are interpreted as chains with $k_z+1$ boson stars, bound by gravity, but kept apart by repulsive scalar interactions. Chains with an odd number of constituents show a spiraling behavior for their ADM mass (and Noether charge) in terms of their angular frequency, similarly to a single fundamental boson star, as long as the gravitational coupling is small; for larger coupling, however, the inner part of the spiral is replaced by a merging with the fundamental branch of radially excited spherical boson stars. Chains with an even number of constituents exhibit a truncated spiral pattern, with only two or three branches, ending at a limiting solution with finite values of ADM mass and Noether charge. |
gr-qc/0412110 | Valery Kiselev | V.V.Kiselev | Radial geodesics as a microscopic origin of black hole entropy. III:
Exercise with the Kerr-Newman black hole | 6 pages, 1 eps-figure, iopart class, acknowledgement extended | null | null | null | gr-qc astro-ph hep-th | null | We specify an angular motion on geodesics to reduce the problem to the case
of radial motion elaborated in previous chapters. An appropriate value of
entropy for a charged and rotating black hole is obtained by calculating the
partition function on thermal geodesics confined under horizons. The quantum
aggregation is classified in a similar way to the Reissner--Nordstrom black
hole.
| [
{
"created": "Wed, 22 Dec 2004 07:58:24 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Dec 2004 08:46:34 GMT",
"version": "v2"
},
{
"created": "Tue, 4 Jan 2005 09:32:33 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Kiselev",
"V. V.",
""
]
] | We specify an angular motion on geodesics to reduce the problem to the case of radial motion elaborated in previous chapters. An appropriate value of entropy for a charged and rotating black hole is obtained by calculating the partition function on thermal geodesics confined under horizons. The quantum aggregation is classified in a similar way to the Reissner--Nordstrom black hole. |
0801.4854 | Tatyana P. Shestakova | T. P. Shestakova | The Wheeler - DeWitt Quantum Geometrodynamics: its fundamental problems
and tendencies of their resolution | 8 pages, no figures | Proceedings of Russian summer school-seminar on Gravitation and
Cosmology "GRACOS-2007", Kazan (2007) P. 179 - 183 | null | null | gr-qc | null | The paper is devoted to fundamental problems of the Wheeler - DeWitt quantum
geometrodynamics, which was the first attempt to apply quantum principles to
the Universe as a whole. Our purpose is to find out the origin of these
problems and follow up their consequences. We start from Dirac generalized
Hamiltonian dynamics as a cornerstone on which the Wheeler - DeWitt theory is
based. We remind the main statements of the famous DeWitt's paper of 1967 and
discuss the flaws of the theory: the well-known problem of time, the problem of
Hilbert space and others. In the concluding part of the paper we consider new
tendencies and approaches to quantum geometrodynamics appeared in the last
decade.
| [
{
"created": "Thu, 31 Jan 2008 12:11:18 GMT",
"version": "v1"
}
] | 2008-02-01 | [
[
"Shestakova",
"T. P.",
""
]
] | The paper is devoted to fundamental problems of the Wheeler - DeWitt quantum geometrodynamics, which was the first attempt to apply quantum principles to the Universe as a whole. Our purpose is to find out the origin of these problems and follow up their consequences. We start from Dirac generalized Hamiltonian dynamics as a cornerstone on which the Wheeler - DeWitt theory is based. We remind the main statements of the famous DeWitt's paper of 1967 and discuss the flaws of the theory: the well-known problem of time, the problem of Hilbert space and others. In the concluding part of the paper we consider new tendencies and approaches to quantum geometrodynamics appeared in the last decade. |
1212.4673 | Mohammad Malekjani | Mohammad Malekjani | Cosmography of interacting generalized QCD ghost dark energy | 20 pages, 8 figures | In. J. Mod. Phys D 22 (2013) 1350084 | 10.1142/S0218271813500843 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Exploring the accelerated expansion of the universe, we investigate the
generalized ghost dark energy (GGDE) model from the statefinder diagnosis
analysis in a flat FRW universe. First we calculate the cosmological evolution
and statefinder trajectories for non-interacting case and then extend this work
by considering the interaction between dark matter and dark energy components.
We show that in the non-interacting case the phantom line can not be crossed
and also he evolutionary trajectories of model in $s-r$ plane can not be
discriminated. It has been shown that the present location of model in $s-r$
plane would be close to observational value for negative values of model
parameter. In the presence of interaction between dark matter and dark energy,
the phantom regime is achieved, the accelerated phase of expansion occurs
sooner compare with non-interacting case. The GGDE model is also discussed from
the viewpoint of perturbation theory by calculating the adiabatic sound speed
of the model. Finally, unlike the non-interacting case, the evolutionary
trajectories in $s-r$ plane can be discriminated in the interacting model. Like
non-interacting model, in the interacting case the present location of GGDE
model is closer to observational value for negative values of model parameter.
| [
{
"created": "Tue, 18 Dec 2012 06:46:39 GMT",
"version": "v1"
},
{
"created": "Sat, 24 Aug 2013 05:49:04 GMT",
"version": "v2"
}
] | 2015-06-12 | [
[
"Malekjani",
"Mohammad",
""
]
] | Exploring the accelerated expansion of the universe, we investigate the generalized ghost dark energy (GGDE) model from the statefinder diagnosis analysis in a flat FRW universe. First we calculate the cosmological evolution and statefinder trajectories for non-interacting case and then extend this work by considering the interaction between dark matter and dark energy components. We show that in the non-interacting case the phantom line can not be crossed and also he evolutionary trajectories of model in $s-r$ plane can not be discriminated. It has been shown that the present location of model in $s-r$ plane would be close to observational value for negative values of model parameter. In the presence of interaction between dark matter and dark energy, the phantom regime is achieved, the accelerated phase of expansion occurs sooner compare with non-interacting case. The GGDE model is also discussed from the viewpoint of perturbation theory by calculating the adiabatic sound speed of the model. Finally, unlike the non-interacting case, the evolutionary trajectories in $s-r$ plane can be discriminated in the interacting model. Like non-interacting model, in the interacting case the present location of GGDE model is closer to observational value for negative values of model parameter. |
1011.1326 | Raymond Chiao Y. | R. Y. Chiao | Test of the superluminality of supercurrents induced by a local electric
field in a superconducting-core coaxial cable | White paper, 6 pages, 1 figure | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An experiment is proposed to test the prediction that induced supercurrents
in a superconductor can become superluminal, as was predicted in the paper by
S.J. Minter, K. Wegter-McNelly, R.Y. Chiao, Physica E 42 (2010) 234.
| [
{
"created": "Fri, 5 Nov 2010 06:03:04 GMT",
"version": "v1"
}
] | 2010-11-08 | [
[
"Chiao",
"R. Y.",
""
]
] | An experiment is proposed to test the prediction that induced supercurrents in a superconductor can become superluminal, as was predicted in the paper by S.J. Minter, K. Wegter-McNelly, R.Y. Chiao, Physica E 42 (2010) 234. |
2311.03433 | Pablo Antonio Cano Molina-Ni\~nirola | Pablo A. Cano, Ludovico Machet, Charlotte Myin | Boson stars with nonlinear sigma models | 12 pages, 5 figures. v2: references added | null | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Boson stars arise as solutions of a massive complex scalar field coupled to
gravity. A variety of scalar potentials, giving rise to different types of
boson stars, have been studied in the literature. Here we study instead the
effect of promoting the kinetic term of the scalar field to a nonlinear sigma
model -- an extension that is naturally motivated by UV completions of gravity
like string theory. We consider the $\mathrm{O}(3)$ and
$\mathrm{SL}(2,\mathbb{R})$ sigma models with minimally interacting potentials
and obtain their boson star solutions. We study the maximum mass and
compactness of the solutions as a function of the curvature of the sigma model
and compare the results to the prototypical case of mini boson stars, which are
recovered in the case of vanishing curvature. The effect of the curvature turns
out to be dramatic. While $\mathrm{O}(3)$ stars are massive and can reach a
size as compact as $R\sim 3.3 GM$, $\mathrm{SL}(2,\mathbb{R})$ stars are much
more diffuse and only astrophysically viable if the bosons are ultralight.
These results show that the scalar kinetic term is at least as important as the
potential in determining the properties of boson stars.
| [
{
"created": "Mon, 6 Nov 2023 19:00:00 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Nov 2023 15:22:21 GMT",
"version": "v2"
}
] | 2023-11-17 | [
[
"Cano",
"Pablo A.",
""
],
[
"Machet",
"Ludovico",
""
],
[
"Myin",
"Charlotte",
""
]
] | Boson stars arise as solutions of a massive complex scalar field coupled to gravity. A variety of scalar potentials, giving rise to different types of boson stars, have been studied in the literature. Here we study instead the effect of promoting the kinetic term of the scalar field to a nonlinear sigma model -- an extension that is naturally motivated by UV completions of gravity like string theory. We consider the $\mathrm{O}(3)$ and $\mathrm{SL}(2,\mathbb{R})$ sigma models with minimally interacting potentials and obtain their boson star solutions. We study the maximum mass and compactness of the solutions as a function of the curvature of the sigma model and compare the results to the prototypical case of mini boson stars, which are recovered in the case of vanishing curvature. The effect of the curvature turns out to be dramatic. While $\mathrm{O}(3)$ stars are massive and can reach a size as compact as $R\sim 3.3 GM$, $\mathrm{SL}(2,\mathbb{R})$ stars are much more diffuse and only astrophysically viable if the bosons are ultralight. These results show that the scalar kinetic term is at least as important as the potential in determining the properties of boson stars. |
2206.14117 | Samuel S\'anchez L\'opez | Konstantinos Dimopoulos, Alexandros Karam, Samuel S\'anchez L\'opez
and Eemeli Tomberg | Palatini $R^2$ Quintessential Inflation | 45 pages, 11 figures | null | 10.1088/1475-7516/2022/10/076 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct a model of quintessential inflation in Palatini $R^2$ gravity
employing a scalar field with a simple exponential potential and coupled to
gravity with a running non-minimal coupling. At early times, the field acts as
the inflaton, while later on it becomes the current dark energy. Combining the
scalar sector with an ideal fluid, we study the cosmological evolution of the
model from inflation all the way to dark energy domination. We interpret the
results in the Einstein frame, where a coupling emerges between the fluid and
the field, feeding energy from the former to the latter during the
matter-dominated era. We perform a numerical scan over the parameter space and
find points that align with observations for both the inflationary CMB data and
the late-time behaviour. The final dark energy density emerges from an
interplay between the model parameters, without requiring the extreme
fine-tuning of the cosmological constant in $\Lambda$CDM.
| [
{
"created": "Tue, 28 Jun 2022 16:23:46 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Nov 2022 17:24:52 GMT",
"version": "v2"
}
] | 2022-11-03 | [
[
"Dimopoulos",
"Konstantinos",
""
],
[
"Karam",
"Alexandros",
""
],
[
"López",
"Samuel Sánchez",
""
],
[
"Tomberg",
"Eemeli",
""
]
] | We construct a model of quintessential inflation in Palatini $R^2$ gravity employing a scalar field with a simple exponential potential and coupled to gravity with a running non-minimal coupling. At early times, the field acts as the inflaton, while later on it becomes the current dark energy. Combining the scalar sector with an ideal fluid, we study the cosmological evolution of the model from inflation all the way to dark energy domination. We interpret the results in the Einstein frame, where a coupling emerges between the fluid and the field, feeding energy from the former to the latter during the matter-dominated era. We perform a numerical scan over the parameter space and find points that align with observations for both the inflationary CMB data and the late-time behaviour. The final dark energy density emerges from an interplay between the model parameters, without requiring the extreme fine-tuning of the cosmological constant in $\Lambda$CDM. |
gr-qc/0205084 | Victor N. Pervushin | V.N. Pervushin and D.V. Proskurin | Cosmic Evolution as Inertial Motion in the Field Space of GR | RevTex file, 23 pages, 1 figure. Talk submitted to the 9th Course on
Astrofundamental Physics (Palermo-Sicily 7-18 September 2002). The abstract,
introduction, and conclusion are changed | null | null | null | gr-qc astro-ph hep-th | null | The identification of a cosmic scale function with the volume integral of a
spacelike hypersurface defines the cosmic evolution in General Relativity as a
collective motion along a geodesic in the field space of the metric components,
considered as the coset of the affine group over the Lorentz one.
The Friedmann equations are derived out of the homogeneous approximation by
the Gibbs averaging exact equations over the relative constant spatial volume.
A direct correspondence between the collective cosmic motion and Special
Relativity is established, to solve the problem of time and energy by analogy
with the solution of this problem for a relativistic particle by Poincare and
Einstein.
A geometrical time interval is introduced into quantum theory of the
relativistic collective motion by the canonical Levi-Civita -- type
transformation in agreement with the correspondence principle with quantum
field theory. In this context the problem of quantum cosmological creation of
visible matter is formulated.
We show that latest observational data can testify to the relative
measurement standard, and the cosmic evolution as an inertial motion along
geodesic in the field space.
| [
{
"created": "Mon, 20 May 2002 09:05:00 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Jul 2002 14:21:28 GMT",
"version": "v2"
},
{
"created": "Wed, 10 Jul 2002 12:27:12 GMT",
"version": "v3"
},
{
"created": "Thu, 25 Jul 2002 12:33:50 GMT",
"version": "v4"
}
] | 2016-08-31 | [
[
"Pervushin",
"V. N.",
""
],
[
"Proskurin",
"D. V.",
""
]
] | The identification of a cosmic scale function with the volume integral of a spacelike hypersurface defines the cosmic evolution in General Relativity as a collective motion along a geodesic in the field space of the metric components, considered as the coset of the affine group over the Lorentz one. The Friedmann equations are derived out of the homogeneous approximation by the Gibbs averaging exact equations over the relative constant spatial volume. A direct correspondence between the collective cosmic motion and Special Relativity is established, to solve the problem of time and energy by analogy with the solution of this problem for a relativistic particle by Poincare and Einstein. A geometrical time interval is introduced into quantum theory of the relativistic collective motion by the canonical Levi-Civita -- type transformation in agreement with the correspondence principle with quantum field theory. In this context the problem of quantum cosmological creation of visible matter is formulated. We show that latest observational data can testify to the relative measurement standard, and the cosmic evolution as an inertial motion along geodesic in the field space. |
gr-qc/0108079 | Claudio Simeone | Hernan De Cicco and Claudio Simeone | Gauge invariance of parametrized systems and path integral quantization | 23 pages | Int.J.Mod.Phys. A14 (1999) 5105-5120 | 10.1142/S0217751X99002414 | null | gr-qc | null | Gauge invariance of systems whose Hamilton-Jacobi equation is separable is
improved by adding surface terms to the action fuctional. The general form of
these terms is given for some complete solutions of the Hamilton-Jacobi
equation. The procedure is applied to the relativistic particle and toy
universes, which are quantized by imposing canonical gauge conditions in the
path integral; in the case of empty models, we first quantize the parametrized
system called ``ideal clock'', and then we examine the possibility of obtaining
the amplitude for the minisuperspaces by matching them with the ideal clock.
The relation existing between the geometrical properties of the constraint
surface and the variables identifying the quantum states in the path integral
is discussed.
| [
{
"created": "Thu, 30 Aug 2001 21:02:23 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"De Cicco",
"Hernan",
""
],
[
"Simeone",
"Claudio",
""
]
] | Gauge invariance of systems whose Hamilton-Jacobi equation is separable is improved by adding surface terms to the action fuctional. The general form of these terms is given for some complete solutions of the Hamilton-Jacobi equation. The procedure is applied to the relativistic particle and toy universes, which are quantized by imposing canonical gauge conditions in the path integral; in the case of empty models, we first quantize the parametrized system called ``ideal clock'', and then we examine the possibility of obtaining the amplitude for the minisuperspaces by matching them with the ideal clock. The relation existing between the geometrical properties of the constraint surface and the variables identifying the quantum states in the path integral is discussed. |
2212.09486 | Thomas Colas | Thomas Colas, Julien Grain, Vincent Vennin | Quantum recoherence in the early universe | 5 + 12 pages, 4 + 2 figures, matches published version in EPL | EPL 142 69002 (2023) | 10.1209/0295-5075/acdd94 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Despite being created through a fundamentally quantum-mechanical process,
cosmological structures have not yet revealed any sign of genuine quantum
correlations. Among the obstructions to the direct detection of quantum
signatures in cosmology, environmental-induced decoherence is arguably one of
the most inevitable. Yet, we discover a mechanism of quantum recoherence for
the adiabatic perturbations when they couple to an entropic sector. After a
transient phase of decoherence, a turning point is reached, recoherence
proceeds and adiabatic perturbations exhibit a large amount of self-coherence
at late-time. This result is also understood by means of a non-Markovian master
equation, which reduces to Wilsonian effective-field theory in the unitary
limit. This allows us to critically assess the validity of open-quantum-system
methods in cosmology and to highlight that re(de)coherence from linear
interactions has no flat-space analogue.
| [
{
"created": "Mon, 19 Dec 2022 14:20:37 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Jun 2023 09:35:18 GMT",
"version": "v2"
}
] | 2023-06-30 | [
[
"Colas",
"Thomas",
""
],
[
"Grain",
"Julien",
""
],
[
"Vennin",
"Vincent",
""
]
] | Despite being created through a fundamentally quantum-mechanical process, cosmological structures have not yet revealed any sign of genuine quantum correlations. Among the obstructions to the direct detection of quantum signatures in cosmology, environmental-induced decoherence is arguably one of the most inevitable. Yet, we discover a mechanism of quantum recoherence for the adiabatic perturbations when they couple to an entropic sector. After a transient phase of decoherence, a turning point is reached, recoherence proceeds and adiabatic perturbations exhibit a large amount of self-coherence at late-time. This result is also understood by means of a non-Markovian master equation, which reduces to Wilsonian effective-field theory in the unitary limit. This allows us to critically assess the validity of open-quantum-system methods in cosmology and to highlight that re(de)coherence from linear interactions has no flat-space analogue. |
1702.05694 | Richard Woodard | S. P. Miao (NCKU, Taiwan), N. C. Tsamis (U. Crete), and R. P. Woodard
(U. Florida) | Invariant Measure of the One Loop Quantum Gravitational Back-Reaction on
Inflation | 26 pages, 2 figures, 1 table, uses LaTeX2e, version 2 slightly
revised for publication | Phys. Rev. D 95, 125008 (2017) | 10.1103/PhysRevD.95.125008 | UFIFT-QG-17-01, CCTP-2017-1 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use dimensional regularization in pure quantum gravity on de Sitter
background to evaluate the one loop expectation value of an invariant operator
which gives the local expansion rate. We show that the renormalization of this
nonlocal composite operator can be accomplished using the counterterms of a
simple local theory of gravity plus matter, at least at one loop order. This
renormalization completely absorbs the one loop correction, which accords with
the prediction that the lowest secular back-reaction should be a 2-loop effect.
| [
{
"created": "Sun, 19 Feb 2017 03:14:11 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Jul 2017 14:47:19 GMT",
"version": "v2"
}
] | 2017-07-17 | [
[
"Miao",
"S. P.",
"",
"NCKU, Taiwan"
],
[
"Tsamis",
"N. C.",
"",
"U. Crete"
],
[
"Woodard",
"R. P.",
"",
"U. Florida"
]
] | We use dimensional regularization in pure quantum gravity on de Sitter background to evaluate the one loop expectation value of an invariant operator which gives the local expansion rate. We show that the renormalization of this nonlocal composite operator can be accomplished using the counterterms of a simple local theory of gravity plus matter, at least at one loop order. This renormalization completely absorbs the one loop correction, which accords with the prediction that the lowest secular back-reaction should be a 2-loop effect. |
1709.03362 | David McNutt | D. D. McNutt, M. A. H. MacCallum, D. Gregoris, A. Forget, A. A. Coley,
P. C. Chavy-Waddy and D. Brooks | Cartan Invariants and Event Horizon Detection, Extended Version | 17 pages. This is an extended version of the article published in
General Relativity and gravitation, it includes additional examples.
Equations in sections 4 and 6 have been corrected | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that it is possible to locate the event horizons of a black hole (in
arbitrary dimensions) as the zeros of certain Cartan invariants. This approach
accounts for the recent results on the detection of stationary horizons using
scalar polynomial curvature invariants, and improves upon them since the
proposed method is computationally less expensive. As an application, we
produce Cartan invariants that locate the event horizons for various exact
four-dimensional and five-dimensional stationary, asymptotically flat (or
(anti) de Sitter) black hole solutions and compare the Cartan invariants with
the corresponding scalar curvature invariants that detect the event horizon. In
particular, for each of the four-dimensional examples we express the scalar
polynomial curvature invariants introduced by Abdelqader and Lake in terms of
the Cartan invariants and show a direct relationship between the scalar
polynomial curvature invariants and the Cartan invariants that detect the
horizon.
| [
{
"created": "Mon, 11 Sep 2017 13:13:46 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Mar 2018 09:22:37 GMT",
"version": "v2"
},
{
"created": "Fri, 10 Jan 2020 13:57:28 GMT",
"version": "v3"
}
] | 2020-01-13 | [
[
"McNutt",
"D. D.",
""
],
[
"MacCallum",
"M. A. H.",
""
],
[
"Gregoris",
"D.",
""
],
[
"Forget",
"A.",
""
],
[
"Coley",
"A. A.",
""
],
[
"Chavy-Waddy",
"P. C.",
""
],
[
"Brooks",
"D.",
""
]
] | We show that it is possible to locate the event horizons of a black hole (in arbitrary dimensions) as the zeros of certain Cartan invariants. This approach accounts for the recent results on the detection of stationary horizons using scalar polynomial curvature invariants, and improves upon them since the proposed method is computationally less expensive. As an application, we produce Cartan invariants that locate the event horizons for various exact four-dimensional and five-dimensional stationary, asymptotically flat (or (anti) de Sitter) black hole solutions and compare the Cartan invariants with the corresponding scalar curvature invariants that detect the event horizon. In particular, for each of the four-dimensional examples we express the scalar polynomial curvature invariants introduced by Abdelqader and Lake in terms of the Cartan invariants and show a direct relationship between the scalar polynomial curvature invariants and the Cartan invariants that detect the horizon. |
2301.01337 | Anjali B Yelikar | A. B. Yelikar (1), V. Delfavero (1 and 2), R. O'Shaughnessy (1) ((1)
Rochester Institute of Technology, (2) NASA Goddard Space Flight Center) | Low-latency parameter inference enabled by a Gaussian likelihood
approximation for RIFT | 4 pages, 2 figures. Comments are welcome. arXiv admin note: text
overlap with arXiv:2011.03571 | null | null | LIGO DCC P2200368 | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Rapid identification, characterization, and localization of gravitational
waves from binary compact object mergers can enable well-informed follow-on
multimessenger observations. In this work, we investigate a small modification
to the RIFT parameter inference pipeline to enable extremely low-latency
inference, tested here for nonprecessing sources.
| [
{
"created": "Tue, 3 Jan 2023 20:09:01 GMT",
"version": "v1"
}
] | 2023-01-05 | [
[
"Yelikar",
"A. B.",
"",
"1 and 2"
],
[
"Delfavero",
"V.",
"",
"1 and 2"
],
[
"O'Shaughnessy",
"R.",
""
]
] | Rapid identification, characterization, and localization of gravitational waves from binary compact object mergers can enable well-informed follow-on multimessenger observations. In this work, we investigate a small modification to the RIFT parameter inference pipeline to enable extremely low-latency inference, tested here for nonprecessing sources. |
gr-qc/0610036 | Francesco Cianfrani dr | Francesco Cianfrani, Irene Milillo, Giovanni Montani | On the geometrization of the electro-magnetic interaction for a spinning
particle | 3 pages, proceedings of the XI Marcel Grossmann meeting on
Relativistic Astrophysics, July 23-29, 2006, Berlin | null | null | null | gr-qc | null | We outline that, in a Kaluza-Klein framework, not only the electro-magnetic
field can be geometrized, but also the dynamics of a charged spinning particle
can be inferred from the motion in a 5-dimensional space-time. This result is
achieved by the dimensional splitting of Papapetrou equations and by proper
identifications of 4-dimensional quantities.
| [
{
"created": "Mon, 9 Oct 2006 15:37:58 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Oct 2006 10:07:52 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Cianfrani",
"Francesco",
""
],
[
"Milillo",
"Irene",
""
],
[
"Montani",
"Giovanni",
""
]
] | We outline that, in a Kaluza-Klein framework, not only the electro-magnetic field can be geometrized, but also the dynamics of a charged spinning particle can be inferred from the motion in a 5-dimensional space-time. This result is achieved by the dimensional splitting of Papapetrou equations and by proper identifications of 4-dimensional quantities. |
gr-qc/0601001 | Carlos F. Sopuerta | A. Passamonti, M. Bruni, L. Gualtieri, A. Nagar, C. F. Sopuerta | Coupling of Radial and Axial non-Radial Oscillations of Compact Stars:
Gravitational Waves from first-order Differential Rotation | RevTeX 4. 23 pages, 13 figures | Phys.Rev. D73 (2006) 084010 | 10.1103/PhysRevD.73.084010 | null | gr-qc astro-ph | null | We investigate the non-linear coupling between radial and non-radial
oscillations of static spherically symmetric neutron stars as a possible
mechanism for the generation of gravitational waves that may lead to observable
signatures. In this paper we concentrate on the axial sector of the non-radial
perturbations. By using a multi-parameter perturbative framework we introduce a
complete description of the non-linear coupling between radial and axial
non-radial oscillations; we study the gauge invariant character of the
associated perturbative variables and develop a computational scheme to evolve
the non-linear coupling perturbations in the time domain. We present results of
simulations corresponding to different physical situations and discuss the
dynamical behaviour of this non-linear coupling. Of particular interest is the
occurrence of signal amplifications in the form of resonance phenomena when a
frequency associated with the radial pulsations is close to a frequency
associated with one of the axial w-modes of the star. Finally, we mention
possible extensions of this work and improvements towards more astrophysically
motivated scenarios.
| [
{
"created": "Sat, 31 Dec 2005 17:20:27 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Passamonti",
"A.",
""
],
[
"Bruni",
"M.",
""
],
[
"Gualtieri",
"L.",
""
],
[
"Nagar",
"A.",
""
],
[
"Sopuerta",
"C. F.",
""
]
] | We investigate the non-linear coupling between radial and non-radial oscillations of static spherically symmetric neutron stars as a possible mechanism for the generation of gravitational waves that may lead to observable signatures. In this paper we concentrate on the axial sector of the non-radial perturbations. By using a multi-parameter perturbative framework we introduce a complete description of the non-linear coupling between radial and axial non-radial oscillations; we study the gauge invariant character of the associated perturbative variables and develop a computational scheme to evolve the non-linear coupling perturbations in the time domain. We present results of simulations corresponding to different physical situations and discuss the dynamical behaviour of this non-linear coupling. Of particular interest is the occurrence of signal amplifications in the form of resonance phenomena when a frequency associated with the radial pulsations is close to a frequency associated with one of the axial w-modes of the star. Finally, we mention possible extensions of this work and improvements towards more astrophysically motivated scenarios. |
2401.05613 | Simona J. Miller | Simona J. Miller, Zoe Ko, Thomas A. Callister, Katerina Chatziioannou | Gravitational waves carry information beyond effective spin parameters
but it is hard to extract | 29 pages including appendices and references, 16 figures | Phys. Rev. D 109, 104036 (2024) | 10.1103/PhysRevD.109.104036 | LIGO-P2300453 | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | Gravitational wave observations of binary black hole mergers probe their
astrophysical origins via the binary spin, namely the spin magnitudes and
directions of each component black hole, together described by six degrees of
freedom. However, the emitted signals primarily depend on two effective spin
parameters that condense the spin degrees of freedom to those parallel and
those perpendicular to the orbital plane. Given this reduction in
dimensionality between the physically relevant problem and what is typically
measurable, we revisit the question of whether information about the component
spin magnitudes and directions can successfully be recovered via
gravitational-wave observations, or if we simply extrapolate information about
the distributions of effective spin parameters. To this end, we simulate three
astrophysical populations with the same underlying effective-spin distribution
but different spin magnitude and tilt distributions, on which we conduct full
individual-event and population-level parameter estimation. We find that
parameterized population models can indeed qualitatively distinguish between
populations with different spin magnitude and tilt distributions at current
sensitivity. However, it remains challenging to either accurately recover the
true distribution or to diagnose biases due to model misspecification. We
attribute the former to practical challenges of dealing with high-dimensional
posterior distributions, and the latter to the fact that each individual event
carries very little information about the full six spin degrees of freedom.
| [
{
"created": "Thu, 11 Jan 2024 01:36:19 GMT",
"version": "v1"
},
{
"created": "Tue, 14 May 2024 02:09:49 GMT",
"version": "v2"
}
] | 2024-05-15 | [
[
"Miller",
"Simona J.",
""
],
[
"Ko",
"Zoe",
""
],
[
"Callister",
"Thomas A.",
""
],
[
"Chatziioannou",
"Katerina",
""
]
] | Gravitational wave observations of binary black hole mergers probe their astrophysical origins via the binary spin, namely the spin magnitudes and directions of each component black hole, together described by six degrees of freedom. However, the emitted signals primarily depend on two effective spin parameters that condense the spin degrees of freedom to those parallel and those perpendicular to the orbital plane. Given this reduction in dimensionality between the physically relevant problem and what is typically measurable, we revisit the question of whether information about the component spin magnitudes and directions can successfully be recovered via gravitational-wave observations, or if we simply extrapolate information about the distributions of effective spin parameters. To this end, we simulate three astrophysical populations with the same underlying effective-spin distribution but different spin magnitude and tilt distributions, on which we conduct full individual-event and population-level parameter estimation. We find that parameterized population models can indeed qualitatively distinguish between populations with different spin magnitude and tilt distributions at current sensitivity. However, it remains challenging to either accurately recover the true distribution or to diagnose biases due to model misspecification. We attribute the former to practical challenges of dealing with high-dimensional posterior distributions, and the latter to the fact that each individual event carries very little information about the full six spin degrees of freedom. |
gr-qc/0002016 | Fredrik Andersson | Fredrik Andersson | Lanczos potentials and curvature-free connections aligned to a geodesic
shear-free expanding null congruence | 34 pages, LaTeX file; New section added, Slight changes in old
sections | null | null | null | gr-qc | null | By the method of rho-integration we obtain all Lanczos potentials L_{ABCA'}
of the Weyl spinor that, in a certain sense, are aligned to a geodesic
shear-free expanding null congruence. We also obtain all spinors
H_{ABA'B'}=Q_{AB}o_{A'}o_{B'}, Q_{AB}=Q_{(AB)} satisfying
nabla_{(A}{}^{B'}H_{BC)A'B'}=L_{ABCA'}. We go on to prove that H_{ABA'B'} can
be chosen so that Gamma_{ABCA'}=nabla_{(A}{}^{B'} H_{B)CA'B'} defines a metric
asymmetric curvature-free connection such that L_{ABCA'}=Gamma_{(ABC)A'} is a
Lanczos potential that is aligned to the geodesic shear-free expanding
congruence. These results are a generalization to a large class of
algebraically special spacetimes (including all vacuum ones for which the
principal null direction is expanding) of the curvature-free connection of the
Kerr spacetime found by Bergqvist and Ludvigsen, which was used in a
construction of quasi-local momentum.
| [
{
"created": "Thu, 3 Feb 2000 10:15:50 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Apr 2000 12:27:01 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Andersson",
"Fredrik",
""
]
] | By the method of rho-integration we obtain all Lanczos potentials L_{ABCA'} of the Weyl spinor that, in a certain sense, are aligned to a geodesic shear-free expanding null congruence. We also obtain all spinors H_{ABA'B'}=Q_{AB}o_{A'}o_{B'}, Q_{AB}=Q_{(AB)} satisfying nabla_{(A}{}^{B'}H_{BC)A'B'}=L_{ABCA'}. We go on to prove that H_{ABA'B'} can be chosen so that Gamma_{ABCA'}=nabla_{(A}{}^{B'} H_{B)CA'B'} defines a metric asymmetric curvature-free connection such that L_{ABCA'}=Gamma_{(ABC)A'} is a Lanczos potential that is aligned to the geodesic shear-free expanding congruence. These results are a generalization to a large class of algebraically special spacetimes (including all vacuum ones for which the principal null direction is expanding) of the curvature-free connection of the Kerr spacetime found by Bergqvist and Ludvigsen, which was used in a construction of quasi-local momentum. |
1301.1070 | Carlos A. R. Herdeiro | Flavio S. Coelho, Carlos Herdeiro and Mengjie Wang | n-DBI gravity, maximal slicing and the Kerr geometry | 3 pages | null | 10.1103/PhysRevD.87.047502 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, in arXiv:1110.0832, we have established that solutions of
Einstein's gravity admitting foliations with a certain geometric condition are
also solutions of n-DBI gravity, arXiv:1109.1468. Here we observe that, in
vacuum, the required geometric condition is fulfilled by the well known maximal
slicing, often used in numerical relativity. As a corollary, we establish that
the Kerr geometry is a solution of n-DBI gravity in the foliation adapted to
Boyer-Lindquist coordinates.
| [
{
"created": "Sun, 6 Jan 2013 22:41:45 GMT",
"version": "v1"
}
] | 2015-06-12 | [
[
"Coelho",
"Flavio S.",
""
],
[
"Herdeiro",
"Carlos",
""
],
[
"Wang",
"Mengjie",
""
]
] | Recently, in arXiv:1110.0832, we have established that solutions of Einstein's gravity admitting foliations with a certain geometric condition are also solutions of n-DBI gravity, arXiv:1109.1468. Here we observe that, in vacuum, the required geometric condition is fulfilled by the well known maximal slicing, often used in numerical relativity. As a corollary, we establish that the Kerr geometry is a solution of n-DBI gravity in the foliation adapted to Boyer-Lindquist coordinates. |
2111.04767 | Shahram Jalalzadeh | S. Jalalzadeh, S. Abarghouei Nejad and P. V. Moniz | On the Hydrogen Atom in the Holographic Universe | 13 pages, to appear in Physica Scripta | Phys. Scr. 96 125320 (2021) | 10.1088/1402-4896/ac3958 | null | gr-qc hep-th math-ph math.MP quant-ph | http://creativecommons.org/licenses/by/4.0/ | We investigate the holographic bound utilizing a homogeneous, isotropic, and
non-relativistic neutral hydrogen gas present in the de Sitter space.
Concretely, we propose to employ de Sitter holography intertwined with quantum
deformation of the hydrogen atom using the framework of quantum groups.
Particularly, the $\mathcal U_q(so(4))$ quantum algebra is used to construct a
finite-dimensional Hilbert space of the hydrogen atom. As a consequence of the
quantum deformation of the hydrogen atom, we demonstrate that the Rydberg
constant is dependent on the de Sitter radius, $L_\Lambda$. This feature is
then extended to obtain a finite-dimensional Hilbert space for the full set of
all hydrogen atoms in the de Sitter universe. We then show that the dimension
of the latter Hilbert space satisfies the holographic bound. We further show
that the mass of a hydrogen atom $m_\text{atom}$, the total number of hydrogen
atoms at the universe, $N$, and the retrieved dimension of the Hilbert space of
neutral hydrogen gas, $\text{Dim}{\mathcal H}_\text{bulk}$, are related to the
de Sitter entropy, $S_\text{dS}$, the Planck mass, $m_\text{Planck}$, the
electron mass, $m_\text{e}$, and the proton mass $m_\text{p}$, by
$m_\text{atom}\simeq m_\text{Planck}S_\text{dS}^{-\frac{1}{6}}$, $N\simeq
S_\text{dS}^\frac{2}{3}$ and $\text{Dim}{\mathcal
H}_\text{bulk}=2^{\frac{m_\text{e}}{m_\text{p}}\alpha^2S_\text{dS}}$,
respectively.
| [
{
"created": "Mon, 8 Nov 2021 19:01:39 GMT",
"version": "v1"
}
] | 2021-12-16 | [
[
"Jalalzadeh",
"S.",
""
],
[
"Nejad",
"S. Abarghouei",
""
],
[
"Moniz",
"P. V.",
""
]
] | We investigate the holographic bound utilizing a homogeneous, isotropic, and non-relativistic neutral hydrogen gas present in the de Sitter space. Concretely, we propose to employ de Sitter holography intertwined with quantum deformation of the hydrogen atom using the framework of quantum groups. Particularly, the $\mathcal U_q(so(4))$ quantum algebra is used to construct a finite-dimensional Hilbert space of the hydrogen atom. As a consequence of the quantum deformation of the hydrogen atom, we demonstrate that the Rydberg constant is dependent on the de Sitter radius, $L_\Lambda$. This feature is then extended to obtain a finite-dimensional Hilbert space for the full set of all hydrogen atoms in the de Sitter universe. We then show that the dimension of the latter Hilbert space satisfies the holographic bound. We further show that the mass of a hydrogen atom $m_\text{atom}$, the total number of hydrogen atoms at the universe, $N$, and the retrieved dimension of the Hilbert space of neutral hydrogen gas, $\text{Dim}{\mathcal H}_\text{bulk}$, are related to the de Sitter entropy, $S_\text{dS}$, the Planck mass, $m_\text{Planck}$, the electron mass, $m_\text{e}$, and the proton mass $m_\text{p}$, by $m_\text{atom}\simeq m_\text{Planck}S_\text{dS}^{-\frac{1}{6}}$, $N\simeq S_\text{dS}^\frac{2}{3}$ and $\text{Dim}{\mathcal H}_\text{bulk}=2^{\frac{m_\text{e}}{m_\text{p}}\alpha^2S_\text{dS}}$, respectively. |
2106.10792 | Fengge Zhang | Fengge Zhang, Jiong Lin and Yizhou Lu | Double-peaked inflation model: Scalar induced gravitational waves and
primordial-black-hole suppression from primordial non-Gaussianity | 29 pages,7 figures | Phys. Rev. D 104, 063515 (2021) | 10.1103/PhysRevD.104.063515 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A significant abundance of primordial black hole (PBH) dark matter can be
produced by curvature perturbations with power spectrum
$\Delta_\zeta^2(k_{\mathrm{peak}})\sim \mathcal{O}(10^{-2})$ at small scales,
associated with the generation of observable scalar induced gravitational waves
(SIGWs). However, the primordial non-Gaussianity may play a non-negligible
role, which is not usually considered. We propose two inflation models that
predict double peaks of order $\mathcal{O}(10^{-2})$ in the power spectrum and
study the effects of primordial non-Gaussianity on PBHs and SIGWs. This model
is driven by a power-law potential, and has a noncanonical kinetic term whose
coupling function admits two peaks. By field-redefinition, it can be recast
into a canonical inflation model with two quasi-inflection points in the
potential. We find that the PBH abundance will be altered saliently if
non-Gaussianity parameter satisfies
$|f_{\mathrm{NL}}(k_{\text{peak}},k_{\text{peak}},k_{\text{peak}})|\gtrsim
\Delta^2_{\zeta}(k_{\mathrm{peak}})/(23\delta^3_c) \sim \mathcal{O}(10^{-2})$.
Whether the PBH abundance is suppressed or enhanced depends on the
$f_{\mathrm{NL}}$ being positive or negative, respectively. In our model,
non-Gaussianity parameter
$f_{\mathrm{NL}}(k_{\mathrm{peak}},k_{\mathrm{peak}},k_{\mathrm{peak}})\sim
\mathcal{O}(1)$ takes positive sign, thus PBH abundance is suppressed
dramatically. On the contrary, SIGWs are insensitive to primordial
non-Gaussianity and hardly affected, so they are still within the sensitivities
of space-based GWs observatories and Square Kilometer Array.
| [
{
"created": "Mon, 21 Jun 2021 01:09:59 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Sep 2021 02:07:03 GMT",
"version": "v2"
}
] | 2021-09-09 | [
[
"Zhang",
"Fengge",
""
],
[
"Lin",
"Jiong",
""
],
[
"Lu",
"Yizhou",
""
]
] | A significant abundance of primordial black hole (PBH) dark matter can be produced by curvature perturbations with power spectrum $\Delta_\zeta^2(k_{\mathrm{peak}})\sim \mathcal{O}(10^{-2})$ at small scales, associated with the generation of observable scalar induced gravitational waves (SIGWs). However, the primordial non-Gaussianity may play a non-negligible role, which is not usually considered. We propose two inflation models that predict double peaks of order $\mathcal{O}(10^{-2})$ in the power spectrum and study the effects of primordial non-Gaussianity on PBHs and SIGWs. This model is driven by a power-law potential, and has a noncanonical kinetic term whose coupling function admits two peaks. By field-redefinition, it can be recast into a canonical inflation model with two quasi-inflection points in the potential. We find that the PBH abundance will be altered saliently if non-Gaussianity parameter satisfies $|f_{\mathrm{NL}}(k_{\text{peak}},k_{\text{peak}},k_{\text{peak}})|\gtrsim \Delta^2_{\zeta}(k_{\mathrm{peak}})/(23\delta^3_c) \sim \mathcal{O}(10^{-2})$. Whether the PBH abundance is suppressed or enhanced depends on the $f_{\mathrm{NL}}$ being positive or negative, respectively. In our model, non-Gaussianity parameter $f_{\mathrm{NL}}(k_{\mathrm{peak}},k_{\mathrm{peak}},k_{\mathrm{peak}})\sim \mathcal{O}(1)$ takes positive sign, thus PBH abundance is suppressed dramatically. On the contrary, SIGWs are insensitive to primordial non-Gaussianity and hardly affected, so they are still within the sensitivities of space-based GWs observatories and Square Kilometer Array. |
1311.4911 | Zahra Amirabi | Z. Amirabi | Black hole solution in third order Lovelock gravity has no Gauss-Bonnet
limit | 4 pages, 1 figure. Final version published in Phys. Rev. D | Phys. Rev. D 88, 087503 (2013) | 10.1103/PhysRevD.88.087503 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit the spherically symmetric third order Lovelock black hole solution
in 7-dimensions. We show that the general solution for the metric function does
not admit the Gauss-Bonnet (GB) limit. This is not expected due to the linear
superposition of the second (GB) and third order Lovelock Lagrangians in the
general action. It is found that the two branches of the GB solutions are
indeed the limit of the other two complex solutions of the field equations in
the third order Lovelock gravity. These two complex solutions could not be
accepted as the solutions of the Einstein's field equations which are supposed
to be real values function on entire real r- axis. A new solution which is only
valid if the third order Lovelock parameter is small is introduced which can be
considered as the natural extension of the general relativity (GR) to the third
order Lovelock modified theory of gravity. We also generalize the discussion to
the higher dimensional third order Lovelock gravity coupled to the matter
sources with cosmological constant.
| [
{
"created": "Tue, 19 Nov 2013 22:38:15 GMT",
"version": "v1"
}
] | 2013-11-21 | [
[
"Amirabi",
"Z.",
""
]
] | We revisit the spherically symmetric third order Lovelock black hole solution in 7-dimensions. We show that the general solution for the metric function does not admit the Gauss-Bonnet (GB) limit. This is not expected due to the linear superposition of the second (GB) and third order Lovelock Lagrangians in the general action. It is found that the two branches of the GB solutions are indeed the limit of the other two complex solutions of the field equations in the third order Lovelock gravity. These two complex solutions could not be accepted as the solutions of the Einstein's field equations which are supposed to be real values function on entire real r- axis. A new solution which is only valid if the third order Lovelock parameter is small is introduced which can be considered as the natural extension of the general relativity (GR) to the third order Lovelock modified theory of gravity. We also generalize the discussion to the higher dimensional third order Lovelock gravity coupled to the matter sources with cosmological constant. |
gr-qc/0012020 | Claudio M. G. de Sousa | Claudio M G de Sousa, Vanda Silveira | Slowly Rotating Boson Fermion Stars | 10 pages, RevTex. Changes on figure 2. Minor modifications on the
text | Int.J.Mod.Phys.D10:881,2001 | 10.1142/S0218271801001360 | ICCMP-2000-010 | gr-qc astro-ph | null | Relativistic prescription is used to study the slow rotation of stars
composed by self-gravitating bosons and fermions (fermions may be considered as
neutrons). Previous results demand that purely boson stars are unable to
display slow rotation, if one uses relativistic prescription with classical
scalar fields. In contrast to this, the present work shows that a combined
boson-neutron star in its ground-state can rotate. Their structure and
stability are analysed under slow rotation approximations.
| [
{
"created": "Tue, 5 Dec 2000 16:11:41 GMT",
"version": "v1"
},
{
"created": "Sun, 4 Feb 2001 14:06:48 GMT",
"version": "v2"
}
] | 2010-11-19 | [
[
"de Sousa",
"Claudio M G",
""
],
[
"Silveira",
"Vanda",
""
]
] | Relativistic prescription is used to study the slow rotation of stars composed by self-gravitating bosons and fermions (fermions may be considered as neutrons). Previous results demand that purely boson stars are unable to display slow rotation, if one uses relativistic prescription with classical scalar fields. In contrast to this, the present work shows that a combined boson-neutron star in its ground-state can rotate. Their structure and stability are analysed under slow rotation approximations. |
1403.7700 | Yakov Itin | Yakov Itin | Covariant jump conditions in electromagnetism | null | Annals of Physics 327.2 (2012): 359-375 | 10.1016/j.aop.2011.09.005 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A generally covariant four-dimensional representation of Maxwell's
electrodynamics in a generic material medium can be achieved straightforwardly
in the metric-free formulation of electromagnetism. In this setup, the
electromagnetic phenomena described by two tensor fields, which satisfy
Maxwell's equations.
A generic tensorial constitutive relation between these fields is an
independent ingredient of the theory. By use of different constitutive
relations (local and non-local, linear and non-linear, etc.), a wide area of
applications can be covered. In the current paper, we present the jump
conditions for the fields and for the energy-momentum tensor on an arbitrarily
moving surface between two media. From the differential and integral Maxwell
equations, we derive the covariant boundary conditions, which are independent
of any metric and connection. These conditions include the covariantly defined
surface current and are applicable to an arbitrarily moving smooth curved
boundary surface. As an application of the presented jump formulas, we derive a
Lorentzian type metric as a condition for existence the wave front in isotropic
media. This result holds for the ordinary materials as well as for the
metamaterials with the negative material constants.
| [
{
"created": "Sun, 30 Mar 2014 04:18:53 GMT",
"version": "v1"
}
] | 2014-04-01 | [
[
"Itin",
"Yakov",
""
]
] | A generally covariant four-dimensional representation of Maxwell's electrodynamics in a generic material medium can be achieved straightforwardly in the metric-free formulation of electromagnetism. In this setup, the electromagnetic phenomena described by two tensor fields, which satisfy Maxwell's equations. A generic tensorial constitutive relation between these fields is an independent ingredient of the theory. By use of different constitutive relations (local and non-local, linear and non-linear, etc.), a wide area of applications can be covered. In the current paper, we present the jump conditions for the fields and for the energy-momentum tensor on an arbitrarily moving surface between two media. From the differential and integral Maxwell equations, we derive the covariant boundary conditions, which are independent of any metric and connection. These conditions include the covariantly defined surface current and are applicable to an arbitrarily moving smooth curved boundary surface. As an application of the presented jump formulas, we derive a Lorentzian type metric as a condition for existence the wave front in isotropic media. This result holds for the ordinary materials as well as for the metamaterials with the negative material constants. |
2305.08816 | Aisha Rashid | M. Farasat Shamir, Aisha Rashid | Bardeen Compact Stars in Modified $f(R)$ Gravity with Conformal Motion | 13 pages, 11 figures | Int. J. Geom. Methods Mod. Phys. 20 (2023) 2350026 | 10.1142/S0219887823500263 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The main emphasis of this paper is to find the viable solutions of Einstein
Maxwell fields equations of compact star in context of modified $f(R)$ theory
of gravity. Two different models of modified $f(R)$ gravity are considered. In
particular, we choose isotropic matter distribution and Bardeen's model for
compact star to find the boundary conditions as an exterior space-time
geometry. We use the conformal Killing geometry to compute the metric
potentials. We discuss the behavior of energy density and pressure distribution
for both models. Moreover, we analyze different physical properties such as
behavior of energy density and pressure, equilibrium conditions, equation of
state parameters, causality conditions and adiabatic index. It is noticed that
both $f(R)$ gravity models are suitable and provides viable results with
Bardeen geometry.
| [
{
"created": "Mon, 15 May 2023 17:27:17 GMT",
"version": "v1"
}
] | 2023-05-16 | [
[
"Shamir",
"M. Farasat",
""
],
[
"Rashid",
"Aisha",
""
]
] | The main emphasis of this paper is to find the viable solutions of Einstein Maxwell fields equations of compact star in context of modified $f(R)$ theory of gravity. Two different models of modified $f(R)$ gravity are considered. In particular, we choose isotropic matter distribution and Bardeen's model for compact star to find the boundary conditions as an exterior space-time geometry. We use the conformal Killing geometry to compute the metric potentials. We discuss the behavior of energy density and pressure distribution for both models. Moreover, we analyze different physical properties such as behavior of energy density and pressure, equilibrium conditions, equation of state parameters, causality conditions and adiabatic index. It is noticed that both $f(R)$ gravity models are suitable and provides viable results with Bardeen geometry. |
gr-qc/0406079 | Charles Wang | Charles H-T Wang | Nonlinear quantum gravity on the constant mean curvature foliation | 14 pages. Classical and Quantum Gravity (To appear) | Class.Quant.Grav. 22 (2005) 33-45 | 10.1088/0264-9381/22/1/003 | null | gr-qc | null | A new approach to quantum gravity is presented based on a nonlinear
quantization scheme for canonical field theories with an implicitly defined
Hamiltonian. The constant mean curvature foliation is employed to eliminate the
momentum constraints in canonical general relativity. It is, however, argued
that the Hamiltonian constraint may be advantageously retained in the reduced
classical system to be quantized. This permits the Hamiltonian constraint
equation to be consistently turned into an expectation value equation on
quantization that describes the scale factor on each spatial hypersurface
characterized by a constant mean exterior curvature. This expectation value
equation augments the dynamical quantum evolution of the unconstrained
conformal three-geometry with a transverse traceless momentum tensor density.
The resulting quantum theory is inherently nonlinear. Nonetheless, it is
unitary and free from a nonlocal and implicit description of the Hamiltonian
operator. Finally, by imposing additional homogeneity symmetries, a broad class
of Bianchi cosmological models are analyzed as nonlinear quantum
minisuperspaces in the context of the proposed theory.
| [
{
"created": "Sun, 20 Jun 2004 10:59:06 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Nov 2004 13:32:27 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Wang",
"Charles H-T",
""
]
] | A new approach to quantum gravity is presented based on a nonlinear quantization scheme for canonical field theories with an implicitly defined Hamiltonian. The constant mean curvature foliation is employed to eliminate the momentum constraints in canonical general relativity. It is, however, argued that the Hamiltonian constraint may be advantageously retained in the reduced classical system to be quantized. This permits the Hamiltonian constraint equation to be consistently turned into an expectation value equation on quantization that describes the scale factor on each spatial hypersurface characterized by a constant mean exterior curvature. This expectation value equation augments the dynamical quantum evolution of the unconstrained conformal three-geometry with a transverse traceless momentum tensor density. The resulting quantum theory is inherently nonlinear. Nonetheless, it is unitary and free from a nonlocal and implicit description of the Hamiltonian operator. Finally, by imposing additional homogeneity symmetries, a broad class of Bianchi cosmological models are analyzed as nonlinear quantum minisuperspaces in the context of the proposed theory. |
1503.05551 | Christian Corda Prof. | Christian Corda | On quasi-normal modes, area quantization and Bohr correspondence
principle | 10 pages, accepted for publication in International Journal of
Theoretical Physics. Some typos have been corrected in this final version.
Some issues in the papers arXiv:1304.1899, arXiv:1503.00565 and
arXiv:1210.7747 has been carefully clarified and refined | Int. Journ. Theor. Phys. 54, 3841 (2015) | 10.1007/s10773-015-2625-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In Int. Journ. Mod. Phys. D 14, 181 (2005), the author Khriplovich verbatim
claims that "the correspondence principle does not dictate any relation between
the asymptotics of quasinormal modes and the spectrum of quantized black holes"
and that "this belief is in conflict with simple physical arguments". In this
paper we analyze Khriplovich's criticisms and realize that they work only for
the original proposal by Hod, while they do not work for the improvements
suggested by Maggiore and recently finalized by the author and collaborators
through a connection between Hawking radiation and black hole (BH) quasi-normal
modes (QNMs). This is a model of quantum BH somewhat similar to the historical
semi-classical model of the structure of a hydrogen atom introduced by Bohr in
1913. Thus, QNMs can be really interpreted as BH quantum levels (the
"electrons" of the "Bohr-like BH model"). Our results have also important
implications on the BH information puzzle.
| [
{
"created": "Wed, 18 Mar 2015 13:29:39 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Mar 2015 12:55:54 GMT",
"version": "v2"
}
] | 2015-09-15 | [
[
"Corda",
"Christian",
""
]
] | In Int. Journ. Mod. Phys. D 14, 181 (2005), the author Khriplovich verbatim claims that "the correspondence principle does not dictate any relation between the asymptotics of quasinormal modes and the spectrum of quantized black holes" and that "this belief is in conflict with simple physical arguments". In this paper we analyze Khriplovich's criticisms and realize that they work only for the original proposal by Hod, while they do not work for the improvements suggested by Maggiore and recently finalized by the author and collaborators through a connection between Hawking radiation and black hole (BH) quasi-normal modes (QNMs). This is a model of quantum BH somewhat similar to the historical semi-classical model of the structure of a hydrogen atom introduced by Bohr in 1913. Thus, QNMs can be really interpreted as BH quantum levels (the "electrons" of the "Bohr-like BH model"). Our results have also important implications on the BH information puzzle. |
1111.5974 | Gustavo Dotti | Gustavo Dotti, Reinaldo J. Gleiser and Ignacio F. Ranea-Sandoval | Unstable fields in Kerr spacetimes | null | Class.Quant.Grav. 29 (2012) 095017 | 10.1088/0264-9381/29/9/095017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that both the interior region $r<M-\sqrt{M^2-a^2}$ of a Kerr black
hole and the $a^2>M^2$ Kerr naked singularity admit unstable solutions of the
Teukolsky equation for any value of the spin weight. For every harmonic number
there is at least one axially symmetric mode that grows exponentially in time
and decays properly in the radial directions. These can be used as Debye
potentials to generate solutions for the scalar, Weyl spinor, Maxwell and
linearized gravity field equations on these backgrounds, satisfying appropriate
spatial boundary conditions and growing exponentially in time, as shown in
detail for the Maxwell case. It is suggested that the existence of the unstable
modes is related to the so called "time machine" region, where the axial
Killing vector field is time-like, and the Teukolsky equation, restricted to
axially symmetric fields, changes its character from hyperbolic to elliptic.
| [
{
"created": "Fri, 25 Nov 2011 13:01:30 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Aug 2012 15:54:49 GMT",
"version": "v2"
}
] | 2012-08-10 | [
[
"Dotti",
"Gustavo",
""
],
[
"Gleiser",
"Reinaldo J.",
""
],
[
"Ranea-Sandoval",
"Ignacio F.",
""
]
] | We show that both the interior region $r<M-\sqrt{M^2-a^2}$ of a Kerr black hole and the $a^2>M^2$ Kerr naked singularity admit unstable solutions of the Teukolsky equation for any value of the spin weight. For every harmonic number there is at least one axially symmetric mode that grows exponentially in time and decays properly in the radial directions. These can be used as Debye potentials to generate solutions for the scalar, Weyl spinor, Maxwell and linearized gravity field equations on these backgrounds, satisfying appropriate spatial boundary conditions and growing exponentially in time, as shown in detail for the Maxwell case. It is suggested that the existence of the unstable modes is related to the so called "time machine" region, where the axial Killing vector field is time-like, and the Teukolsky equation, restricted to axially symmetric fields, changes its character from hyperbolic to elliptic. |
1008.2955 | Mahdi Godazgar | Mahdi Godazgar | Spinor classification of the Weyl tensor in five dimensions | 40 pages | Class.Quant.Grav.27:245013,2010 | 10.1088/0264-9381/27/24/245013 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the spinor classification of the Weyl tensor in five
dimensions due to De Smet. We show that a previously overlooked reality
condition reduces the number of possible types in the classification. We
classify all vacuum solutions belonging to the most special algebraic type. The
connection between this spinor and the tensor classification due to Coley,
Milson, Pravda and Pravdov\'a is investigated and the relation between most of
the types in each of the classifications is given. We show that the black ring
is algebraically general in the spinor classification.
| [
{
"created": "Tue, 17 Aug 2010 20:00:00 GMT",
"version": "v1"
}
] | 2010-11-30 | [
[
"Godazgar",
"Mahdi",
""
]
] | We investigate the spinor classification of the Weyl tensor in five dimensions due to De Smet. We show that a previously overlooked reality condition reduces the number of possible types in the classification. We classify all vacuum solutions belonging to the most special algebraic type. The connection between this spinor and the tensor classification due to Coley, Milson, Pravda and Pravdov\'a is investigated and the relation between most of the types in each of the classifications is given. We show that the black ring is algebraically general in the spinor classification. |
gr-qc/0502035 | Metin Gurses | Metin Gurses and Ozgur Sarioglu | Accelerated Levi-Civita-Bertotti-Robinson Metric in D-Dimensions | Latex File, 12 pages | Gen.Rel.Grav. 37 (2005) 2015-2022 | 10.1007/s10714-005-0176-y | null | gr-qc hep-th | null | A conformally flat accelerated charge metric is found in an arbitrary
dimension $D$. It is a solution of the Einstein-Maxwell-null fluid with a
cosmological constant in $D \ge 4$ dimensions. When the acceleration is zero
our solution reduces to the Levi-Civita-Bertotti-Robinson metric. We show that
the charge loses its energy, for all dimensions, due to the acceleration.
| [
{
"created": "Wed, 9 Feb 2005 12:10:49 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Gurses",
"Metin",
""
],
[
"Sarioglu",
"Ozgur",
""
]
] | A conformally flat accelerated charge metric is found in an arbitrary dimension $D$. It is a solution of the Einstein-Maxwell-null fluid with a cosmological constant in $D \ge 4$ dimensions. When the acceleration is zero our solution reduces to the Levi-Civita-Bertotti-Robinson metric. We show that the charge loses its energy, for all dimensions, due to the acceleration. |
1609.02875 | Henri Roesch | Henri Roesch | Proof of a Null Penrose Conjecture using a new Quasi-local Mass | null | null | null | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We define an explicit quasi-local mass functional which is non-decreasing
along all foliations (satisfying a convexity assumption) of null cones. We use
this new functional to prove the null Penrose conjecture under fairly generic
conditions.
| [
{
"created": "Fri, 9 Sep 2016 17:47:06 GMT",
"version": "v1"
}
] | 2016-09-12 | [
[
"Roesch",
"Henri",
""
]
] | We define an explicit quasi-local mass functional which is non-decreasing along all foliations (satisfying a convexity assumption) of null cones. We use this new functional to prove the null Penrose conjecture under fairly generic conditions. |
1507.02902 | Giampiero Esposito Dr. | Emmanuele Battista, Simone Dell'Agnello, Giampiero Esposito, Luciano
Di Fiore, Jules Simo, Aniello Grado | Earth-Moon Lagrangian points as a testbed for general relativity and
effective field theories of gravity | 41 pages, 9 figures. Comments in the very end of Sec. VI have been
amended and shortened. The last typos have been corrected | Phys. Rev. D92, 064045 (2015) | 10.1103/PhysRevD.92.064045 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the restricted four-body problem consisting of the Earth, the Moon and the
Sun as the primaries and a spacecraft as the planetoid, we take into account
the solar perturbation in the description of the motion of a spacecraft in the
vicinity of the stable Earth-Moon libration points L4 and L5 both in the
classical regime and in the context of effective field theories of gravity. We
then evaluate the location of all Lagrangian points in the Earth-Moon system
within the framework of general relativity. For the points L4 and L5, the
corrections of coordinates are of order a few millimeters. After that, we set
up a scheme where the theory which is quantum corrected has as its classical
counterpart the Einstein theory, instead of the Newtonian one. By virtue of the
effective-gravity correction to the longdistance form of the potential among
two point masses, all terms involving the ratio between the gravitational
radius of the primary and its separation from the planetoid get modified.
Within this framework, for the Lagrangian points of stable equilibrium, we find
quantum corrections of order two millimeters, whereas for Lagrangian points of
unstable equilibrium we find quantum corrections below a millimeter. Finally,
general relativity corrections to Newtonian position of collinear Lagrangian
points turn out to be below the millimiter, whereas on stable equilibrium
points they are of order of a few millimiters.
| [
{
"created": "Fri, 10 Jul 2015 13:55:35 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Sep 2015 14:21:18 GMT",
"version": "v2"
},
{
"created": "Thu, 12 May 2016 12:41:45 GMT",
"version": "v3"
},
{
"created": "Sun, 15 May 2016 16:27:51 GMT",
"version": "v4"
}
] | 2016-05-17 | [
[
"Battista",
"Emmanuele",
""
],
[
"Dell'Agnello",
"Simone",
""
],
[
"Esposito",
"Giampiero",
""
],
[
"Di Fiore",
"Luciano",
""
],
[
"Simo",
"Jules",
""
],
[
"Grado",
"Aniello",
""
]
] | In the restricted four-body problem consisting of the Earth, the Moon and the Sun as the primaries and a spacecraft as the planetoid, we take into account the solar perturbation in the description of the motion of a spacecraft in the vicinity of the stable Earth-Moon libration points L4 and L5 both in the classical regime and in the context of effective field theories of gravity. We then evaluate the location of all Lagrangian points in the Earth-Moon system within the framework of general relativity. For the points L4 and L5, the corrections of coordinates are of order a few millimeters. After that, we set up a scheme where the theory which is quantum corrected has as its classical counterpart the Einstein theory, instead of the Newtonian one. By virtue of the effective-gravity correction to the longdistance form of the potential among two point masses, all terms involving the ratio between the gravitational radius of the primary and its separation from the planetoid get modified. Within this framework, for the Lagrangian points of stable equilibrium, we find quantum corrections of order two millimeters, whereas for Lagrangian points of unstable equilibrium we find quantum corrections below a millimeter. Finally, general relativity corrections to Newtonian position of collinear Lagrangian points turn out to be below the millimiter, whereas on stable equilibrium points they are of order of a few millimiters. |
1711.09627 | Roberto A. Sussman | Germ\'an Izquierdo, Roberto C Blanquet-Jaramillo and Roberto A Sussman | Interactive mixture of inhomogeneous dark fluids driven by dark energy:
a dynamical systems analysis | 23 pages, IOP format, 8 figures | null | 10.1140/epjc/s10052-018-5699-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the evolution of an inhomogeneous mixture of non-relativistic
pressureless cold dark matter (CDM), coupled to dark energy (DE) characterised
by the equation of state parameter $w<-1/3$, with the interaction term
proportional to the DE density. This coupled mixture is the source of a
spherically symmetric Lema\^\ itre-Tolman-Bondi (LTB) metric admitting an
asymptotic Friedman-Lema\^\ itre-Robertson-Walker (FLRW) background. Einstein's
equations reduce to a 5-dimensional autonomous dynamical system involving
quasi--local variables related to suitable averages of covariant scalars and
their fluctuations. The phase space evolution around the critical points
(past/future attractors and five saddles) is examined in detail. For all
parameter values and both directions of energy flow (CDM to DE and DE to CDM)
the phase space trajectories are compatible with a physically plausible early
cosmic times behaviour near the past attractor. This result compares favourably
with mixtures with the interaction driven by the CDM density in which
conditions for a physically plausible past evolution are more restrictive.
Numerical examples are provided describing the evolution of an initial profile
that can be associated with idealised structure formation scenarios
| [
{
"created": "Mon, 27 Nov 2017 11:32:37 GMT",
"version": "v1"
}
] | 2018-04-18 | [
[
"Izquierdo",
"Germán",
""
],
[
"Blanquet-Jaramillo",
"Roberto C",
""
],
[
"Sussman",
"Roberto A",
""
]
] | We examine the evolution of an inhomogeneous mixture of non-relativistic pressureless cold dark matter (CDM), coupled to dark energy (DE) characterised by the equation of state parameter $w<-1/3$, with the interaction term proportional to the DE density. This coupled mixture is the source of a spherically symmetric Lema\^\ itre-Tolman-Bondi (LTB) metric admitting an asymptotic Friedman-Lema\^\ itre-Robertson-Walker (FLRW) background. Einstein's equations reduce to a 5-dimensional autonomous dynamical system involving quasi--local variables related to suitable averages of covariant scalars and their fluctuations. The phase space evolution around the critical points (past/future attractors and five saddles) is examined in detail. For all parameter values and both directions of energy flow (CDM to DE and DE to CDM) the phase space trajectories are compatible with a physically plausible early cosmic times behaviour near the past attractor. This result compares favourably with mixtures with the interaction driven by the CDM density in which conditions for a physically plausible past evolution are more restrictive. Numerical examples are provided describing the evolution of an initial profile that can be associated with idealised structure formation scenarios |
gr-qc/0104047 | Juan Eloy Ayon Beato | Eloy Ay\'on-Beato, Alberto Garc\'ia, Alfredo Mac\'ias, Hernando
Quevedo | Static Black Holes of Metric-Affine Gravity in the Presence of Matter | 19 pages, RevTex, accepted for publication in Phys. Rev. D;
duplication of refs. corrected | Phys.Rev.D64:024026,2001 | 10.1103/PhysRevD.64.024026 | null | gr-qc | null | We investigate spherically symmetric and static gravitational fields
representing black hole configurations in the framework of metric-affine gauge
theories of gravity (MAG) in the presence of different matter fields. It is
shown that in the triplet ansatz sector of MAG, black hole configurations in
the presence of non-Abelian matter fields allow the existence of black hole
hair. We analyze several cases of matter fields characterized by the presence
of hair and for all of them we show the validity of the no short hair
conjecture.
| [
{
"created": "Mon, 16 Apr 2001 20:25:22 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Apr 2001 19:28:26 GMT",
"version": "v2"
}
] | 2016-08-16 | [
[
"Ayón-Beato",
"Eloy",
""
],
[
"García",
"Alberto",
""
],
[
"Macías",
"Alfredo",
""
],
[
"Quevedo",
"Hernando",
""
]
] | We investigate spherically symmetric and static gravitational fields representing black hole configurations in the framework of metric-affine gauge theories of gravity (MAG) in the presence of different matter fields. It is shown that in the triplet ansatz sector of MAG, black hole configurations in the presence of non-Abelian matter fields allow the existence of black hole hair. We analyze several cases of matter fields characterized by the presence of hair and for all of them we show the validity of the no short hair conjecture. |
2109.06901 | Paul Chesler | Paul M. Chesler | Hairy black resonators and the AdS$_4$ superradiant instability | 12 pages, 7 figures, v2: typos corrected and minor clarifications
added | null | 10.1103/PhysRevD.105.024026 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The superradiant instability of Kerr-AdS black holes is studied by
numerically solving the full 3+1 dimensional Einstein equations. We find that
the superradiant instability results in a two stage process with distinct
initial and secondary instabilities. At the end of the secondary instability
the geometry oscillates at several distinct fundamental frequencies -- a
multi-oscillating black hole. The multi-oscillating black hole is remarkably
close to a black resonator, albeit with a bit of gravitational hair. During the
hairy black resonator epoch, the evolution of the horizon area is consistent
with the exponential approach to a constant. By employing different seed
perturbations in the initial Kerr-AdS geometry, we also demonstrate that the
black resonator's hair is not unique. In the dual quantum field theory
description, rotation invariance is spontaneously broken and the energy density
is negative in some regions, signaling an exotic state of matter which does not
relax to a stationary configuration.
| [
{
"created": "Tue, 14 Sep 2021 18:01:38 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Sep 2021 14:48:36 GMT",
"version": "v2"
}
] | 2022-01-19 | [
[
"Chesler",
"Paul M.",
""
]
] | The superradiant instability of Kerr-AdS black holes is studied by numerically solving the full 3+1 dimensional Einstein equations. We find that the superradiant instability results in a two stage process with distinct initial and secondary instabilities. At the end of the secondary instability the geometry oscillates at several distinct fundamental frequencies -- a multi-oscillating black hole. The multi-oscillating black hole is remarkably close to a black resonator, albeit with a bit of gravitational hair. During the hairy black resonator epoch, the evolution of the horizon area is consistent with the exponential approach to a constant. By employing different seed perturbations in the initial Kerr-AdS geometry, we also demonstrate that the black resonator's hair is not unique. In the dual quantum field theory description, rotation invariance is spontaneously broken and the energy density is negative in some regions, signaling an exotic state of matter which does not relax to a stationary configuration. |
1302.5253 | Valter Moretti | Giovanni Collini (Leipzig U.), Valter Moretti (Trento U.), Nicola
Pinamonti (Genova U.) | Tunnelling black-hole radiation with $\phi^3$ self-interaction: one-loop
computation for Rindler Killing horizons | Some changes in the text, acknowledgments added, accepted for
publication in Letters in Mathematical Physics | Lett. Math. Phys. 104 (2014) 217-232 | 10.1007/s11005-013-0663-0 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Tunnelling processes through black hole horizons have recently been
investigated in the framework of WKB theory discovering interesting interplay
with the Hawking radiation. A more precise and general account of that
phenomenon has been subsequently given within the framework of QFT in curved
spacetime by two of the authors of the present paper. In particular, it has
been shown that, in the limit of sharp localization on opposite sides of a
Killing horizon, the quantum correlation functions of a scalar field appear to
have thermal nature, and the tunnelling probability is proportional to
$\exp\{-\beta_{Hawking} E\}$. This local result is valid in every spacetime
including a local Killing horizon, no field equation is necessary, while a
suitable choice for the quantum state is relevant. Indeed, the two point
function has to verify a short-distance condition weaker than the Hadamard one.
In this paper we consider a massive scalar quantum field with a $\phi^3$
self-interaction and we investigate the issue whether or not the black hole
radiation can be handled at perturbative level, including the renormalisation
contributions. We prove that, for the simplest model of the Killing horizon
generated by the boost in Minkowski spacetime, and referring to Minkowski
vacuum, the tunnelling probability in the limit of sharp localization on
opposite sides of the horizon preserves the thermal form proportional to
$\exp\{-\beta_H E\}$ even taking the one-loop renormalisation corrections into
account. A similar result is expected to hold for the Unruh state in the
Kruskal manifold, since that state is Hadamard and looks like Minkowski vacuum
close to the horizon.
| [
{
"created": "Thu, 21 Feb 2013 11:27:49 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Feb 2013 15:08:19 GMT",
"version": "v2"
},
{
"created": "Tue, 16 Apr 2013 12:47:46 GMT",
"version": "v3"
},
{
"created": "Wed, 16 Oct 2013 11:56:34 GMT",
"version": "v4"
}
] | 2014-01-21 | [
[
"Collini",
"Giovanni",
"",
"Leipzig U."
],
[
"Moretti",
"Valter",
"",
"Trento U."
],
[
"Pinamonti",
"Nicola",
"",
"Genova U."
]
] | Tunnelling processes through black hole horizons have recently been investigated in the framework of WKB theory discovering interesting interplay with the Hawking radiation. A more precise and general account of that phenomenon has been subsequently given within the framework of QFT in curved spacetime by two of the authors of the present paper. In particular, it has been shown that, in the limit of sharp localization on opposite sides of a Killing horizon, the quantum correlation functions of a scalar field appear to have thermal nature, and the tunnelling probability is proportional to $\exp\{-\beta_{Hawking} E\}$. This local result is valid in every spacetime including a local Killing horizon, no field equation is necessary, while a suitable choice for the quantum state is relevant. Indeed, the two point function has to verify a short-distance condition weaker than the Hadamard one. In this paper we consider a massive scalar quantum field with a $\phi^3$ self-interaction and we investigate the issue whether or not the black hole radiation can be handled at perturbative level, including the renormalisation contributions. We prove that, for the simplest model of the Killing horizon generated by the boost in Minkowski spacetime, and referring to Minkowski vacuum, the tunnelling probability in the limit of sharp localization on opposite sides of the horizon preserves the thermal form proportional to $\exp\{-\beta_H E\}$ even taking the one-loop renormalisation corrections into account. A similar result is expected to hold for the Unruh state in the Kruskal manifold, since that state is Hadamard and looks like Minkowski vacuum close to the horizon. |
1204.0055 | Yuri Bonder | Yuri Bonder | Lorentz Invariant Phenomenological Model of Quantum Gravity: A
Minimalistic Presentation | Work presented at the IX Workshop of the Mexican Gravity Division | null | 10.1063/1.4748552 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The purpose of this paper is to give a minimalistic and self-contained
presentation of a Lorentz Invariant phenomenological model of Quantum Gravity.
| [
{
"created": "Sat, 31 Mar 2012 01:15:00 GMT",
"version": "v1"
}
] | 2015-06-04 | [
[
"Bonder",
"Yuri",
""
]
] | The purpose of this paper is to give a minimalistic and self-contained presentation of a Lorentz Invariant phenomenological model of Quantum Gravity. |
2107.01738 | Daniela Doneva | Daniela D. Doneva, Stoytcho S. Yazadjiev | Beyond the spontaneous scalarization: New fully nonlinear dynamical
mechanism for formation of scalarized black holes | additionally, classes of sGB theories are considered where both the
standard and the nonlinear scalarization are present with a smooth connection
between both; 8 pages, 6 figures | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present letter we show the existence of a fully nonlinear dynamical
mechanism for the formation of scalarized black holes which is different from
the spontaneous scalarization. We consider a class of scalar-Gauss-Bonnet
gravity theories within which no tachyonic instability can occur. Although the
Schwarzschild black holes are linearly stable against scalar perturbations, we
show dynamically that for certain choices of the coupling function they are
unstable against nonlinear scalar perturbations. This nonlinear instability
leads to the formation of new black holes with scalar hair. The fully nonlinear
and self-consistent study of the equilibrium black holes reveals that the
spectrum of solutions is more complicated and more than one scalarized branch
can exist. We have also considered classes of scalar-Gauss-Bonnet theories
where both the standard and the nonlinear scalarization can be present, and
they are smoothly connected that completes in an interesting way the picture of
black hole scalarization. The fully nonlinear (de)scalarization of a
Schwarzschild black hole will always happen with a jump because the stable
"scalarized branch" is not continuously connected to the Schwarzschild one that
can leave clear observational signatures.
| [
{
"created": "Sun, 4 Jul 2021 21:26:36 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Nov 2021 07:21:10 GMT",
"version": "v2"
}
] | 2021-11-05 | [
[
"Doneva",
"Daniela D.",
""
],
[
"Yazadjiev",
"Stoytcho S.",
""
]
] | In the present letter we show the existence of a fully nonlinear dynamical mechanism for the formation of scalarized black holes which is different from the spontaneous scalarization. We consider a class of scalar-Gauss-Bonnet gravity theories within which no tachyonic instability can occur. Although the Schwarzschild black holes are linearly stable against scalar perturbations, we show dynamically that for certain choices of the coupling function they are unstable against nonlinear scalar perturbations. This nonlinear instability leads to the formation of new black holes with scalar hair. The fully nonlinear and self-consistent study of the equilibrium black holes reveals that the spectrum of solutions is more complicated and more than one scalarized branch can exist. We have also considered classes of scalar-Gauss-Bonnet theories where both the standard and the nonlinear scalarization can be present, and they are smoothly connected that completes in an interesting way the picture of black hole scalarization. The fully nonlinear (de)scalarization of a Schwarzschild black hole will always happen with a jump because the stable "scalarized branch" is not continuously connected to the Schwarzschild one that can leave clear observational signatures. |
2405.12644 | Hassan Basari V.T. | Hassan Basari V. T. | Unified formalism for the emergence of space in non-equilibrium
description | 11 Pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Previous studies indicate that the expansion law in emergence of space can be
derived from the first law f thermodynamics. It has been proposed a unified
formulation for the expansion law applicable to a general set of gravity
theories in equilibrium description. In that formulation, which is based on the
first law of thermodynamics, the non-equilibrium terms are ignored.
Additionally, the structure of surface degrees of freedom in that formulation
deviates from the standard notion, where $N_{sur} \ne 4S$ in general theories
of gravity. This motivates us to develop a new unified formulation for the
expansion law by incorporating non-equilibrium terms into the first law of
thermodynamics. In this work, we formulate a unified expansion law in a
non-equilibrium context, utilizing the first law of thermodynamics along with
the definition of an effective Misner-Sharp energy. Compared to previous
generalizations of the expansion law, our formulation reconciles the basic
definition of surface degrees of freedom $N_{sur} = 4S$ for a general set of
gravity theories. The unified expansion law in non-equilibrium not only
highlights the direct relationship between the rate of areal volume and the
difference in degrees of freedom between the surface and bulk
$(N_{sur}-N_{bulk})$, but also reveals an inverse correlation with the density
of surface degrees of freedom. We also demonstrate that the unified expansion
law is instrumental in deriving the expansion law for a general set of gravity
theories, including those with higher-order curvature corrections such as
$f(R)$ theories of gravity, which require a non-equilibrium description.
| [
{
"created": "Tue, 21 May 2024 09:55:34 GMT",
"version": "v1"
}
] | 2024-05-22 | [
[
"T.",
"Hassan Basari V.",
""
]
] | Previous studies indicate that the expansion law in emergence of space can be derived from the first law f thermodynamics. It has been proposed a unified formulation for the expansion law applicable to a general set of gravity theories in equilibrium description. In that formulation, which is based on the first law of thermodynamics, the non-equilibrium terms are ignored. Additionally, the structure of surface degrees of freedom in that formulation deviates from the standard notion, where $N_{sur} \ne 4S$ in general theories of gravity. This motivates us to develop a new unified formulation for the expansion law by incorporating non-equilibrium terms into the first law of thermodynamics. In this work, we formulate a unified expansion law in a non-equilibrium context, utilizing the first law of thermodynamics along with the definition of an effective Misner-Sharp energy. Compared to previous generalizations of the expansion law, our formulation reconciles the basic definition of surface degrees of freedom $N_{sur} = 4S$ for a general set of gravity theories. The unified expansion law in non-equilibrium not only highlights the direct relationship between the rate of areal volume and the difference in degrees of freedom between the surface and bulk $(N_{sur}-N_{bulk})$, but also reveals an inverse correlation with the density of surface degrees of freedom. We also demonstrate that the unified expansion law is instrumental in deriving the expansion law for a general set of gravity theories, including those with higher-order curvature corrections such as $f(R)$ theories of gravity, which require a non-equilibrium description. |
1112.0488 | Llu\'is Bel | Llu\'is Bel | Uniform rotation | 6 pages, formula (18) changed, Sect. 2 improved | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe the space-time model of a uniformly rotating frame of reference
satisfying the Helmholtz free mobility postulate, as we implemented it in a
preceding article \cite{Bel1}, and we discuss the implications of this model as
it concerns the problematic of the one way or two ways velocity of light
derived from the model and its relationship with the universal constant c.
| [
{
"created": "Fri, 2 Dec 2011 15:51:57 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Dec 2011 19:22:27 GMT",
"version": "v2"
},
{
"created": "Wed, 14 Jan 2015 08:54:35 GMT",
"version": "v3"
}
] | 2015-01-15 | [
[
"Bel",
"Lluís",
""
]
] | We describe the space-time model of a uniformly rotating frame of reference satisfying the Helmholtz free mobility postulate, as we implemented it in a preceding article \cite{Bel1}, and we discuss the implications of this model as it concerns the problematic of the one way or two ways velocity of light derived from the model and its relationship with the universal constant c. |
gr-qc/0612146 | Gregory Adkins | Gregory S. Adkins, Jordan McDonnell, Richard N. Fell | Cosmological perturbations on local systems | 10 pages | Phys.Rev.D75:064011,2007 | 10.1103/PhysRevD.75.064011 | null | gr-qc | null | We study the effect of cosmological expansion on orbits--galactic, planetary,
or atomic--subject to an inverse-square force law. We obtain the laws of motion
for gravitational or electrical interactions from general relativity--in
particular, we find the gravitational field of a mass distribution in an
expanding universe by applying perturbation theory to the Robertson-Walker
metric. Cosmological expansion induces an ($\ddot a/a) \vec r$ force where
$a(t)$ is the cosmological scale factor. In a locally Newtonian framework, we
show that the $(\ddot a/a) \vec r$ term represents the effect of a continuous
distribution of cosmological material in Hubble flow, and that the total force
on an object, due to the cosmological material plus the matter perturbation,
can be represented as the negative gradient of a gravitational potential whose
source is the material actually present. We also consider the effect on local
dynamics of the cosmological constant. We calculate the perihelion precession
of elliptical orbits due to the cosmological constant induced force, and work
out a generalized virial relation applicable to gravitationally bound clusters.
| [
{
"created": "Fri, 22 Dec 2006 15:35:16 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Adkins",
"Gregory S.",
""
],
[
"McDonnell",
"Jordan",
""
],
[
"Fell",
"Richard N.",
""
]
] | We study the effect of cosmological expansion on orbits--galactic, planetary, or atomic--subject to an inverse-square force law. We obtain the laws of motion for gravitational or electrical interactions from general relativity--in particular, we find the gravitational field of a mass distribution in an expanding universe by applying perturbation theory to the Robertson-Walker metric. Cosmological expansion induces an ($\ddot a/a) \vec r$ force where $a(t)$ is the cosmological scale factor. In a locally Newtonian framework, we show that the $(\ddot a/a) \vec r$ term represents the effect of a continuous distribution of cosmological material in Hubble flow, and that the total force on an object, due to the cosmological material plus the matter perturbation, can be represented as the negative gradient of a gravitational potential whose source is the material actually present. We also consider the effect on local dynamics of the cosmological constant. We calculate the perihelion precession of elliptical orbits due to the cosmological constant induced force, and work out a generalized virial relation applicable to gravitationally bound clusters. |
1711.01276 | Wolfgang Wieland | Wolfgang Wieland | Quantum gravity in three dimensions, Witten spinors and the quantisation
of length | 22 pages, one figure | Nuclear Physics B 930 (2018) 219-234 | 10.1016/j.nuclphysb.2018.02.022 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, I investigate the quantisation of length in euclidean quantum
gravity in three dimensions. The starting point is the classical hamiltonian
formalism in a cylinder of finite radius. At this finite boundary, a counter
term is introduced that couples the gravitational field in the interior to a
two-dimensional conformal field theory for an SU(2) boundary spinor, whose norm
determines the conformal factor between the fiducial boundary metric and the
physical metric in the bulk. The equations of motion for this boundary spinor
are derived from the boundary action and turn out to be the two-dimensional
analogue of the Witten equations appearing in Witten's proof of the positive
mass theorem. The paper concludes with some comments on the resulting quantum
theory. It is shown, in particular, that the length of a one-dimensional cross
section of the boundary turns into a number operator on the Fock space of the
theory. The spectrum of this operator is discrete and matches the results from
loop quantum gravity in the spin network representation.
| [
{
"created": "Fri, 3 Nov 2017 18:00:08 GMT",
"version": "v1"
}
] | 2018-04-06 | [
[
"Wieland",
"Wolfgang",
""
]
] | In this paper, I investigate the quantisation of length in euclidean quantum gravity in three dimensions. The starting point is the classical hamiltonian formalism in a cylinder of finite radius. At this finite boundary, a counter term is introduced that couples the gravitational field in the interior to a two-dimensional conformal field theory for an SU(2) boundary spinor, whose norm determines the conformal factor between the fiducial boundary metric and the physical metric in the bulk. The equations of motion for this boundary spinor are derived from the boundary action and turn out to be the two-dimensional analogue of the Witten equations appearing in Witten's proof of the positive mass theorem. The paper concludes with some comments on the resulting quantum theory. It is shown, in particular, that the length of a one-dimensional cross section of the boundary turns into a number operator on the Fock space of the theory. The spectrum of this operator is discrete and matches the results from loop quantum gravity in the spin network representation. |
2003.11748 | Teruaki Suyama | Teruaki Suyama | On arrival time difference between lensed gravitational waves and light | Version published in ApJ | null | 10.3847/1538-4357/ab8d3f | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is known that geometrical optics no longer applies to the gravitational
lensing if the wavelength of a propagating wave becomes comparable to or larger
than the Schwarzshild radius of a lensing object. We investigate the
propagation of gravitational waves in wave optics, particularly focusing on the
difference between their arrival time and the arrival time of light. We argue
that, contrary to the observation in the previous work, gravitational waves
never arrive at an observer earlier than light when both gravitational waves
and light are emitted from a same source simultaneously.
| [
{
"created": "Thu, 26 Mar 2020 05:32:39 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Jul 2020 10:16:01 GMT",
"version": "v2"
}
] | 2020-07-23 | [
[
"Suyama",
"Teruaki",
""
]
] | It is known that geometrical optics no longer applies to the gravitational lensing if the wavelength of a propagating wave becomes comparable to or larger than the Schwarzshild radius of a lensing object. We investigate the propagation of gravitational waves in wave optics, particularly focusing on the difference between their arrival time and the arrival time of light. We argue that, contrary to the observation in the previous work, gravitational waves never arrive at an observer earlier than light when both gravitational waves and light are emitted from a same source simultaneously. |
2201.00743 | Pardyumn Kumar Sahoo | Oleksii Sokoliuk, Zinnat Hassan, P. K. Sahoo, Alexander Baransky | Traversable wormholes with charge and non-commutative geometry in the
$f(Q)$ gravity | Annals of Physics revised version | Annals of Physics, 443 (2022) 168968 | 10.1016/j.aop.2022.168968 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We consider modified symmetric teleparallel gravity (STG), in which
gravitational Lagrangian is given by the arbitrary function of non-metricity
scalar $Q$ to study static and spherically symmetric charged traversable
wormhole solutions with non-commutative background geometry. The matter source
at the wormhole throat is acknowledged to be anisotropic, and the redshift
function has a constant value (thus, our wormhole solution is non-tidal). We
study the obtained field equations with the two functional forms of $f(Q)$ STG
models, such as linear $f(Q)=\alpha Q+\beta$ and non-linear $f(Q)=Q+mQ^n$
models under Gaussian and Lorentzian distributions. Our analysis found the
exact wormhole solutions for the linear STG model only. Also, for the
non-linear model, we derived numerically suitable forms of wormhole shape
functions directly from the modified Einstein Field Equations (EFEs). Besides,
we probed these models via Null, Dominant, and Strong energy conditions with
respect to free Modified gravity (MOG) parameters $\alpha$, $\beta$, $m$, and
$n$. We also used Tolman-Oppenheimer-Vokloff (TOV) equation to investigate the
stability of wormhole anisotropic matter in considered MOG. Finally, we plot
the equation of state.
| [
{
"created": "Mon, 3 Jan 2022 16:37:10 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Mar 2022 16:12:14 GMT",
"version": "v2"
},
{
"created": "Sun, 22 May 2022 12:50:28 GMT",
"version": "v3"
},
{
"created": "Fri, 10 Jun 2022 11:21:59 GMT",
"version": "v4"
}
] | 2022-06-30 | [
[
"Sokoliuk",
"Oleksii",
""
],
[
"Hassan",
"Zinnat",
""
],
[
"Sahoo",
"P. K.",
""
],
[
"Baransky",
"Alexander",
""
]
] | We consider modified symmetric teleparallel gravity (STG), in which gravitational Lagrangian is given by the arbitrary function of non-metricity scalar $Q$ to study static and spherically symmetric charged traversable wormhole solutions with non-commutative background geometry. The matter source at the wormhole throat is acknowledged to be anisotropic, and the redshift function has a constant value (thus, our wormhole solution is non-tidal). We study the obtained field equations with the two functional forms of $f(Q)$ STG models, such as linear $f(Q)=\alpha Q+\beta$ and non-linear $f(Q)=Q+mQ^n$ models under Gaussian and Lorentzian distributions. Our analysis found the exact wormhole solutions for the linear STG model only. Also, for the non-linear model, we derived numerically suitable forms of wormhole shape functions directly from the modified Einstein Field Equations (EFEs). Besides, we probed these models via Null, Dominant, and Strong energy conditions with respect to free Modified gravity (MOG) parameters $\alpha$, $\beta$, $m$, and $n$. We also used Tolman-Oppenheimer-Vokloff (TOV) equation to investigate the stability of wormhole anisotropic matter in considered MOG. Finally, we plot the equation of state. |
gr-qc/0309018 | Yi Ling | Yi Ling and Hongbao Zhang | Quasinormal modes prefer supersymmetry ? | 3 pages | Phys.Rev. D68 (2003) 101501 | 10.1103/PhysRevD.68.101501 | null | gr-qc hep-th | null | One ambiguity in loop quantum gravity is the appearance of a free parameter
which is called Immirzi parameter. Recently Dreyer has argued that this
parameter may be fixed by considering the quasinormal mode spectrum of black
holes, while at the price of changing the gauge group to SO(3) rather than the
original one SU(2). Physically such a replacement is not quite natural or
desirable. In this paper we study the relationship between the black hole
entropy and the quasi normal mode spectrum in the loop quantization of N=1
supergravity. We find that a single value of the Immirzi parameter agrees with
the semiclassical expectations as well. But in this case the lowest
supersymmetric representation dominates, fitting well with the result based on
statistical consideration. This suggests that, so long as fermions are included
in the theory, supersymemtry may be favored for the consistency of the low
energy limit of loop quantum gravity.
| [
{
"created": "Wed, 3 Sep 2003 09:18:29 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Ling",
"Yi",
""
],
[
"Zhang",
"Hongbao",
""
]
] | One ambiguity in loop quantum gravity is the appearance of a free parameter which is called Immirzi parameter. Recently Dreyer has argued that this parameter may be fixed by considering the quasinormal mode spectrum of black holes, while at the price of changing the gauge group to SO(3) rather than the original one SU(2). Physically such a replacement is not quite natural or desirable. In this paper we study the relationship between the black hole entropy and the quasi normal mode spectrum in the loop quantization of N=1 supergravity. We find that a single value of the Immirzi parameter agrees with the semiclassical expectations as well. But in this case the lowest supersymmetric representation dominates, fitting well with the result based on statistical consideration. This suggests that, so long as fermions are included in the theory, supersymemtry may be favored for the consistency of the low energy limit of loop quantum gravity. |
2204.09040 | Elda Guzman Elda Guzman-Herrera | Elda Guzman-Herrera, Nora Breton | Light propagating in a Born-Infeld background as seen by an accelerated
observer | 32 pages, 15 figures | null | 10.1002/andp.202200043 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-nd/4.0/ | We study the propagation of light in the Born-Infeld (BI) background as seen
by an accelerated observer. In a Born-Infeld electromagnetic field, light
trajectories are governed by the null geodesics of the effective optical
metric. The accelerated observer is in a Rindler frame, a situation that,
according to the Einstein Equivalence Principle, is equivalent to being in a
uniform gravitational field. The phase velocity of light propagating through a
purely magnetic or electric BI background is determined as measured by the
Rindler observer. The BI field and the acceleration of the frame have opposite
effects on the propagating light: while the intense electric or magnetic BI
background slows down the velocity of light, in the accelerated frame light may
exceed its velocity in vacuum. We consider light propagating parallel or
transversal to the acceleration direction of the Rindler frame. The redshift of
light pulses sent from one Rindler observer to another, in the BI background,
is calculated as well.
| [
{
"created": "Tue, 19 Apr 2022 17:58:34 GMT",
"version": "v1"
}
] | 2022-08-24 | [
[
"Guzman-Herrera",
"Elda",
""
],
[
"Breton",
"Nora",
""
]
] | We study the propagation of light in the Born-Infeld (BI) background as seen by an accelerated observer. In a Born-Infeld electromagnetic field, light trajectories are governed by the null geodesics of the effective optical metric. The accelerated observer is in a Rindler frame, a situation that, according to the Einstein Equivalence Principle, is equivalent to being in a uniform gravitational field. The phase velocity of light propagating through a purely magnetic or electric BI background is determined as measured by the Rindler observer. The BI field and the acceleration of the frame have opposite effects on the propagating light: while the intense electric or magnetic BI background slows down the velocity of light, in the accelerated frame light may exceed its velocity in vacuum. We consider light propagating parallel or transversal to the acceleration direction of the Rindler frame. The redshift of light pulses sent from one Rindler observer to another, in the BI background, is calculated as well. |
0907.3596 | Luc Blanchet | Luc Blanchet | Post-Newtonian theory and the two-body problem | 42 pages, to appear in the book "Mass and Motion in General
Relativity", proceedings of the C.N.R.S. School in Orleans, France, eds. L.
Blanchet, A. Spallicci and B. Whiting | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Reliable predictions of general relativity theory are extracted using
approximation methods. Among these, the powerful post-Newtonian approximation
provides us with our best insights into the problems of motion and
gravitational radiation of systems of compact objects. This approximation has
reached an impressive mature status, because of important progress regarding
its theoretical foundations, and the successful construction of templates of
gravitational waves emitted by inspiralling compact binaries. The
post-Newtonian predictions are routinely used for searching and analyzing the
very weak signals of gravitational waves in current generations of detectors.
High-accuracy comparisons with the results of numerical simulations for the
merger and ring-down of binary black holes are going on. In this article we
give an overview on the general formulation of the post-Newtonian approximation
and present up-to-date results for the templates of compact binary inspiral.
| [
{
"created": "Tue, 21 Jul 2009 09:53:53 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Mar 2010 19:25:17 GMT",
"version": "v2"
}
] | 2010-03-12 | [
[
"Blanchet",
"Luc",
""
]
] | Reliable predictions of general relativity theory are extracted using approximation methods. Among these, the powerful post-Newtonian approximation provides us with our best insights into the problems of motion and gravitational radiation of systems of compact objects. This approximation has reached an impressive mature status, because of important progress regarding its theoretical foundations, and the successful construction of templates of gravitational waves emitted by inspiralling compact binaries. The post-Newtonian predictions are routinely used for searching and analyzing the very weak signals of gravitational waves in current generations of detectors. High-accuracy comparisons with the results of numerical simulations for the merger and ring-down of binary black holes are going on. In this article we give an overview on the general formulation of the post-Newtonian approximation and present up-to-date results for the templates of compact binary inspiral. |
2404.02630 | Ana Luc\'ia Baez-Camargo | Ana Luc\'ia B\'aez-Camargo, Daniel Hartley, Christian K\"ading, Ivette
Fuentes-Guridi | Dynamical Casimir effect with screened scalar fields | 16+6 pages, 2 figures, 1 table | null | null | null | gr-qc astro-ph.CO hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Understanding the nature of dark energy and dark matter is one of modern
physics' greatest open problems. Scalar-tensor theories with screened scalar
fields like the chameleon model are among the most popular proposed solutions.
In this article, we present the first analysis of the impact of a chameleon
field on the dynamical Casimir effect, whose main feature is the particle
production associated with a resonant condition of boundary periodic motion in
cavities. For this, we employ a recently developed method to compute the
evolution of confined quantum scalar fields in a globally hyperbolic spacetime
by means of time-dependent Bogoliubov transformations. As a result, we show
that particle production is reduced due to the presence of the chameleon field.
In addition, our results for the Bogoliubov coefficients and the mean number of
created particles agree with known results in the absence of a chameleon field.
Our results initiate the discussion of the evolution of quantum fields on
screened scalar field backgrounds.
| [
{
"created": "Wed, 3 Apr 2024 10:36:42 GMT",
"version": "v1"
}
] | 2024-04-09 | [
[
"Báez-Camargo",
"Ana Lucía",
""
],
[
"Hartley",
"Daniel",
""
],
[
"Käding",
"Christian",
""
],
[
"Fuentes-Guridi",
"Ivette",
""
]
] | Understanding the nature of dark energy and dark matter is one of modern physics' greatest open problems. Scalar-tensor theories with screened scalar fields like the chameleon model are among the most popular proposed solutions. In this article, we present the first analysis of the impact of a chameleon field on the dynamical Casimir effect, whose main feature is the particle production associated with a resonant condition of boundary periodic motion in cavities. For this, we employ a recently developed method to compute the evolution of confined quantum scalar fields in a globally hyperbolic spacetime by means of time-dependent Bogoliubov transformations. As a result, we show that particle production is reduced due to the presence of the chameleon field. In addition, our results for the Bogoliubov coefficients and the mean number of created particles agree with known results in the absence of a chameleon field. Our results initiate the discussion of the evolution of quantum fields on screened scalar field backgrounds. |
1602.07434 | Alan Cornell | G. E. Harmsen, C. H. Chen, H. T. Cho and A. S. Cornell | Absorption probabilities associated with spin-3/2 particles near
$N$-dimensional Schwarzschild black holes | 6 pages, 2 figures, to appear in the proceedings of the High Energy
Particle Physics Workshop 2016 (iThemba Labs, Johannesburg, South Africa) | null | 10.1088/1742-6596/802/1/012002 | WITS-MITP-021 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In June 2015 the Large Hadron Collider was able to produce collisions with an
energy of 13TeV, where collisions at these energy levels may allow for the
formation of higher dimensional black holes. In order to detect these higher
dimensional black holes we require an understanding of their emission spectra.
One way of determining this is by looking at the absorption probabilities
associated with the black hole. In this proceedings we will look at the
absorption probability for spin-3/2 particles near $N$-dimensional
Schwarzschild black holes. We will show how the Unruh method is used to
determine these probabilities for low energy particles. We then use the
Wentzel-Kramers-Brillouin approximation in order to determine these absorption
probabilities for the entire possible energy range.
| [
{
"created": "Wed, 24 Feb 2016 08:54:54 GMT",
"version": "v1"
}
] | 2017-04-05 | [
[
"Harmsen",
"G. E.",
""
],
[
"Chen",
"C. H.",
""
],
[
"Cho",
"H. T.",
""
],
[
"Cornell",
"A. S.",
""
]
] | In June 2015 the Large Hadron Collider was able to produce collisions with an energy of 13TeV, where collisions at these energy levels may allow for the formation of higher dimensional black holes. In order to detect these higher dimensional black holes we require an understanding of their emission spectra. One way of determining this is by looking at the absorption probabilities associated with the black hole. In this proceedings we will look at the absorption probability for spin-3/2 particles near $N$-dimensional Schwarzschild black holes. We will show how the Unruh method is used to determine these probabilities for low energy particles. We then use the Wentzel-Kramers-Brillouin approximation in order to determine these absorption probabilities for the entire possible energy range. |
gr-qc/0512079 | Ezra Newman | Ezra T. Newman | Asymptotic twistor Theory and the Kerr Theorem | 11 | Class.Quant.Grav. 23 (2006) 3385-3392 | 10.1088/0264-9381/23/10/009 | null | gr-qc | null | We first review asymptotic twistor theory with its real subspace of null
asymptotic twistors. This is followed by a description of an asymptotic version
of the Kerr theorem that produces regular asymptotically shear free null
geodesic congruences in arbitrary asymptotically flat Einstein or
Einstein-Maxwell spacetimes.
| [
{
"created": "Tue, 13 Dec 2005 19:00:05 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Newman",
"Ezra T.",
""
]
] | We first review asymptotic twistor theory with its real subspace of null asymptotic twistors. This is followed by a description of an asymptotic version of the Kerr theorem that produces regular asymptotically shear free null geodesic congruences in arbitrary asymptotically flat Einstein or Einstein-Maxwell spacetimes. |
gr-qc/0102019 | Julien Sylvestre | Julien Sylvestre | A nonlinear detection algorithm for periodic signals in gravitational
wave detectors | 9 pages, 3 figures, to appear in Phys. Rev. D | Phys.Rev. D63 (2001) 082004 | 10.1103/PhysRevD.63.082004 | null | gr-qc | null | We present an algorithm for the detection of periodic sources of
gravitational waves with interferometric detectors that is based on a special
symmetry of the problem: the contributions to the phase modulation of the
signal from the earth rotation are exactly equal and opposite at any two
instants of time separated by half a sidereal day; the corresponding is true
for the contributions from the earth orbital motion for half a sidereal year,
assuming a circular orbit. The addition of phases through multiplications of
the shifted time series gives a demodulated signal; specific attention is given
to the reduction of noise mixing resulting from these multiplications. We
discuss the statistics of this algorithm for all-sky searches (which include a
parameterization of the source spin-down), in particular its optimal
sensitivity as a function of required computational power. Two specific
examples of all-sky searches (broad-band and narrow-band) are explored
numerically, and their performances are compared with the stack-slide technique
(P. R. Brady, T. Creighton, Phys. Rev. D, 61, 082001).
| [
{
"created": "Tue, 6 Feb 2001 02:28:00 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Sylvestre",
"Julien",
""
]
] | We present an algorithm for the detection of periodic sources of gravitational waves with interferometric detectors that is based on a special symmetry of the problem: the contributions to the phase modulation of the signal from the earth rotation are exactly equal and opposite at any two instants of time separated by half a sidereal day; the corresponding is true for the contributions from the earth orbital motion for half a sidereal year, assuming a circular orbit. The addition of phases through multiplications of the shifted time series gives a demodulated signal; specific attention is given to the reduction of noise mixing resulting from these multiplications. We discuss the statistics of this algorithm for all-sky searches (which include a parameterization of the source spin-down), in particular its optimal sensitivity as a function of required computational power. Two specific examples of all-sky searches (broad-band and narrow-band) are explored numerically, and their performances are compared with the stack-slide technique (P. R. Brady, T. Creighton, Phys. Rev. D, 61, 082001). |
1606.06558 | Saheb Soroushfar | Bahareh Hoseini, Reza Saffari, Saheb Soroushfar | Study of the geodesic equations of a spherical symmetric spacetime in
conformal gravity | 23 pages,1 table,23 figures | Classical and Quantum Gravity, 2017 (34) | 10.1088/1361-6382/aa5a63 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Set of analytic solutions of the geodesic equation in a spherical conformal
spacetime is presented. Solutions of this geodesics can be expressed in terms
of the Weierstrass {\wp} function and the Kleinian {\sigma} function. Using
conserved energy and angular momentum we can characterize the different orbits.
Also, considering parametric diagrams and effective potentials, we plot some
possible orbits. Moreover, with the help of analytical solutions, we
investigate the light deflection for such an escape orbit.
| [
{
"created": "Tue, 21 Jun 2016 13:23:45 GMT",
"version": "v1"
}
] | 2020-04-07 | [
[
"Hoseini",
"Bahareh",
""
],
[
"Saffari",
"Reza",
""
],
[
"Soroushfar",
"Saheb",
""
]
] | Set of analytic solutions of the geodesic equation in a spherical conformal spacetime is presented. Solutions of this geodesics can be expressed in terms of the Weierstrass {\wp} function and the Kleinian {\sigma} function. Using conserved energy and angular momentum we can characterize the different orbits. Also, considering parametric diagrams and effective potentials, we plot some possible orbits. Moreover, with the help of analytical solutions, we investigate the light deflection for such an escape orbit. |
gr-qc/0110105 | Iver H. Brevik | I. Brevik and S. D. Odintsov | On the Cardy-Verlinde Entropy Formula in Viscous Cosmology | 11 pages, LaTeX, no figures. Discussion added in Sec. 2. To appear in
Phys. Rev. D | Phys.Rev.D65:067302,2002 | 10.1103/PhysRevD.65.067302 | null | gr-qc hep-th | null | The results of the paper of Verlinde [hep-th/0008140], discussing the
holographic principle in a radiation dominated universe, are extended when
allowing the cosmic fluid to possess a bulk viscosity. This corresponds to a
non-conformally invariant theory. The generalization of the Cardy-Verlinde
entropy formula to the case of a viscous universe seems from a formal point of
view to be possible, although we question on physical grounds some elements in
this kind of theory, especially the manner in which the Casimir energy is
evaluated. Our discussion suggests that for non-conformally invariant theories
the holographic definition of Casimir energy should be modified.
| [
{
"created": "Wed, 24 Oct 2001 11:54:11 GMT",
"version": "v1"
},
{
"created": "Sat, 29 Dec 2001 15:06:05 GMT",
"version": "v2"
}
] | 2009-01-14 | [
[
"Brevik",
"I.",
""
],
[
"Odintsov",
"S. D.",
""
]
] | The results of the paper of Verlinde [hep-th/0008140], discussing the holographic principle in a radiation dominated universe, are extended when allowing the cosmic fluid to possess a bulk viscosity. This corresponds to a non-conformally invariant theory. The generalization of the Cardy-Verlinde entropy formula to the case of a viscous universe seems from a formal point of view to be possible, although we question on physical grounds some elements in this kind of theory, especially the manner in which the Casimir energy is evaluated. Our discussion suggests that for non-conformally invariant theories the holographic definition of Casimir energy should be modified. |
gr-qc/0111045 | Wu Shuangqin | S. Q. Wu, X. Cai | Hawking Radiation of Photons in a Vaidya-de Sitter Black Hole | Latex, 10 pages, no figure, to appear in Int. J. Theor. Phys. 41
(2002) No. 3 | Int.J.Theor.Phys. 41 (2002) 559-567 | null | null | gr-qc | null | Hawking evaporation of photons in a Vaidya-de Sitter black hole is
investigated by using the method of generalized tortoise coordinate
transformation. Both the location and the temperature of the event horizon
depend on the time. It is shown that Hawking radiation of photons exists only
for the complex Maxwell scalar $\phi_0$ in the advanced Eddington-Finkelstein
coordinate system. This asymmetry of Hawking radiation for different components
of Maxwell fields probably arises from the asymmetry of spacetime in the
advanced Eddington-Finkelstein coordinate system. It is shown that the black
body radiant spectrum of photons resembles that of Klein-Gordon particles.
PACS numbers: 04.70.Dy, 97.60.Lf
| [
{
"created": "Thu, 15 Nov 2001 08:54:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Wu",
"S. Q.",
""
],
[
"Cai",
"X.",
""
]
] | Hawking evaporation of photons in a Vaidya-de Sitter black hole is investigated by using the method of generalized tortoise coordinate transformation. Both the location and the temperature of the event horizon depend on the time. It is shown that Hawking radiation of photons exists only for the complex Maxwell scalar $\phi_0$ in the advanced Eddington-Finkelstein coordinate system. This asymmetry of Hawking radiation for different components of Maxwell fields probably arises from the asymmetry of spacetime in the advanced Eddington-Finkelstein coordinate system. It is shown that the black body radiant spectrum of photons resembles that of Klein-Gordon particles. PACS numbers: 04.70.Dy, 97.60.Lf |
2203.14610 | Andronikos Paliathanasis | Andronikos Paliathanasis | Hyperbolic inflation in the Jordan frame | 16 pages, 3 figures | Universe 2022, 8(4), 199 | 10.3390/universe8040199 | null | gr-qc hep-ph math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | We consider a multi-scalar field model in the Jordan frame which can be seen
as a two-scalar field model where the Brans-Dicke field interacts in the
kinetic part with the second scalar field. This theory under a conformal
transformation reduces to the hyperbolic inflation. We show that scaling
solutions and the de Sitter universe are provided by theory. In the study of
asymptotic dynamics, we determine an attractor where all the fluid sources
contribute in the cosmological fluid. This attractor is always a spiral and it
can be seen as the analogue of the hyperbolic inflation in the Jordan frame.
| [
{
"created": "Mon, 28 Mar 2022 09:43:51 GMT",
"version": "v1"
}
] | 2022-03-29 | [
[
"Paliathanasis",
"Andronikos",
""
]
] | We consider a multi-scalar field model in the Jordan frame which can be seen as a two-scalar field model where the Brans-Dicke field interacts in the kinetic part with the second scalar field. This theory under a conformal transformation reduces to the hyperbolic inflation. We show that scaling solutions and the de Sitter universe are provided by theory. In the study of asymptotic dynamics, we determine an attractor where all the fluid sources contribute in the cosmological fluid. This attractor is always a spiral and it can be seen as the analogue of the hyperbolic inflation in the Jordan frame. |
1003.5108 | S Habib Mazharimousavi | S. Habib Mazharimousavi and M. Halilsoy | Revisiting the dyonic Majumdar-Papapetrou black holes | 16 pages, 3 figures. | TJP 40, 163 (2016) | 10.3906/fiz-1506-19 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend the Majumdar-Papapetrou (MP) solution of the Einstein-Maxwell (EM)
equations which is implied generally for static electric charge in non-rotating
metrics to encompass equally well magnetic charges. In the absence of Higgs and
non-Abelian gauge fields, 'dyonic' is to be understood in this simpler sense.
Cosmologically this may have far-reaching consequences, to the extent that
existence of multi-magnetic monopole black holes may become a reality in our
universe. Infalling charged particle geodesics may reveal, through particular
integrals, their inner secrets which are screened from our observation.
| [
{
"created": "Fri, 26 Mar 2010 10:50:53 GMT",
"version": "v1"
}
] | 2016-05-31 | [
[
"Mazharimousavi",
"S. Habib",
""
],
[
"Halilsoy",
"M.",
""
]
] | We extend the Majumdar-Papapetrou (MP) solution of the Einstein-Maxwell (EM) equations which is implied generally for static electric charge in non-rotating metrics to encompass equally well magnetic charges. In the absence of Higgs and non-Abelian gauge fields, 'dyonic' is to be understood in this simpler sense. Cosmologically this may have far-reaching consequences, to the extent that existence of multi-magnetic monopole black holes may become a reality in our universe. Infalling charged particle geodesics may reveal, through particular integrals, their inner secrets which are screened from our observation. |
1901.03965 | Antoine Folacci | Antoine Folacci and Mohamed Ould El Hadj | Regge pole description of scattering of scalar and electromagnetic waves
by a Schwarzschild black hole | v2: We have added some considerations relevant to the long-wavelength
regime in order to emphasize the role of background integrals. v3: Close to
the published version. We have provided an analytical approximation
describing both the black hole glory and the orbiting oscillations | Phys. Rev. D 99, 104079 (2019) | 10.1103/PhysRevD.99.104079 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit the problem of scalar and electromagnetic waves impinging upon a
Schwarzschild black hole from complex angular momentum techniques. We focus
more particularly on the associated differential scattering cross sections. We
derive an exact representation of the corresponding scattering amplitudes by
replacing the discrete sum over integer values of the angular momentum which
defines their partial wave expansions by a background integral in the complex
angular momentum plane plus a sum over the Regge poles of the $S$-matrix
involving the associated residues. We show that, surprisingly, the background
integral is numerically negligible for intermediate and high frequencies and,
as a consequence, that the cross sections can be reconstructed in terms of
Regge poles with very good agreement. We show in particular that, for large
values of the scattering angle, a small number of Regge poles permits us to
describe the black hole glory and that, by increasing the number of Regge
poles, we can reconstruct very efficiently the differential scattering cross
sections for small and intermediate scattering angles and therefore describe
the orbiting oscillations. In fact, in the short-wavelength regime, the sum
over Regge poles allows us to extract by resummation the information encoded in
the partial wave expansion defining a scattering amplitude and, moreover, to
overcome the difficulties linked to its lack of convergence due to the
long-range nature of the fields propagating on the black hole. As a
consequence, from asymptotic expressions for the lowest Regge poles and the
associated residues based on the correspondence Regge poles -- ``surface
waves'' propagating close to the photon sphere, we can provide an analytical
approximation describing both the black hole glory and a large part of the
orbiting oscillations. We finally discuss the role of the background integral
for low frequencies.
| [
{
"created": "Sun, 13 Jan 2019 12:02:32 GMT",
"version": "v1"
},
{
"created": "Sun, 10 Feb 2019 17:44:25 GMT",
"version": "v2"
},
{
"created": "Sun, 2 Jun 2019 05:14:06 GMT",
"version": "v3"
}
] | 2019-06-04 | [
[
"Folacci",
"Antoine",
""
],
[
"Hadj",
"Mohamed Ould El",
""
]
] | We revisit the problem of scalar and electromagnetic waves impinging upon a Schwarzschild black hole from complex angular momentum techniques. We focus more particularly on the associated differential scattering cross sections. We derive an exact representation of the corresponding scattering amplitudes by replacing the discrete sum over integer values of the angular momentum which defines their partial wave expansions by a background integral in the complex angular momentum plane plus a sum over the Regge poles of the $S$-matrix involving the associated residues. We show that, surprisingly, the background integral is numerically negligible for intermediate and high frequencies and, as a consequence, that the cross sections can be reconstructed in terms of Regge poles with very good agreement. We show in particular that, for large values of the scattering angle, a small number of Regge poles permits us to describe the black hole glory and that, by increasing the number of Regge poles, we can reconstruct very efficiently the differential scattering cross sections for small and intermediate scattering angles and therefore describe the orbiting oscillations. In fact, in the short-wavelength regime, the sum over Regge poles allows us to extract by resummation the information encoded in the partial wave expansion defining a scattering amplitude and, moreover, to overcome the difficulties linked to its lack of convergence due to the long-range nature of the fields propagating on the black hole. As a consequence, from asymptotic expressions for the lowest Regge poles and the associated residues based on the correspondence Regge poles -- ``surface waves'' propagating close to the photon sphere, we can provide an analytical approximation describing both the black hole glory and a large part of the orbiting oscillations. We finally discuss the role of the background integral for low frequencies. |
1811.01330 | Deobrat Singh | Deobrat Singh and Supriya Kar | Emergent D-instanton as a source of Dark Energy | 11 pages, Typos corrected and added new citations | Brazilian Journal of Physics 2019 | 10.1007/s13538-019-00635-y | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit a non-perturbative formulation leading to a vacuum created
gravitational pair of (33)-brane by a Poincare dual higher form U (1) gauge
theory on a D4 -brane. In particular, the analysis has revealed a dynamical
geometric torsion H 3 for an on-shell Neveu-Schwarz (NS) form on a fat 4-brane.
We argue that a D-instanton can be a viable candidate to incorporate the
quintessence correction hidden to an emergent (3 + 1)-dimensional brane
universe. It is shown that a dynamical non-perturbative correction may be
realized with an axionic scalar QFT on an emergent anti 3-brane within a
gravitational pair. The theoretical tool provokes thought to believe for an
extra instantaneous dimension transverse to our classical brane-universe in an
emergent scenario. Interestingly a D-instanton correction, sourced by an axion
on an anti 3-brane, may serve as a potential candidate to explain the
accelerated rate of expansion of our 3-brane universe and may provide a clue to
the origin of dark energy.
| [
{
"created": "Sun, 4 Nov 2018 07:33:44 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Nov 2018 08:48:42 GMT",
"version": "v2"
},
{
"created": "Thu, 14 Feb 2019 00:29:52 GMT",
"version": "v3"
}
] | 2019-02-15 | [
[
"Singh",
"Deobrat",
""
],
[
"Kar",
"Supriya",
""
]
] | We revisit a non-perturbative formulation leading to a vacuum created gravitational pair of (33)-brane by a Poincare dual higher form U (1) gauge theory on a D4 -brane. In particular, the analysis has revealed a dynamical geometric torsion H 3 for an on-shell Neveu-Schwarz (NS) form on a fat 4-brane. We argue that a D-instanton can be a viable candidate to incorporate the quintessence correction hidden to an emergent (3 + 1)-dimensional brane universe. It is shown that a dynamical non-perturbative correction may be realized with an axionic scalar QFT on an emergent anti 3-brane within a gravitational pair. The theoretical tool provokes thought to believe for an extra instantaneous dimension transverse to our classical brane-universe in an emergent scenario. Interestingly a D-instanton correction, sourced by an axion on an anti 3-brane, may serve as a potential candidate to explain the accelerated rate of expansion of our 3-brane universe and may provide a clue to the origin of dark energy. |
1209.6218 | Hassan Hamad | M. I. Wanas and H. A. Hassan | Torsion and Problems of Standard Cosmology | 18 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The field equation of orthodox general relativity are written in the context
of a geometry with non-vanishing torsion, the Absolute Parallelism (AP)
geometry. An AP-structure, with homogeneity and isotropy, is used for
cosmological applications. The resulting dynamical equations are those of
FRW-Standard cosmology, which have many problems e.g. singularity, particle
horizons, ...etc. We suggest a new scheme for investigating the effect of
torsion on the dynamics of FRW-Cosmology, without changing the basic structure
of general relativity. It is shown that some of these problems will disappear
if the torsion, associated with AP-structure used, is inserted in to the
dynamical equations. Diagnose shows that problems arise when GR is written in
the context of a geometry with vanishing torsion, the Riemannian geometry. This
reflects the importance of using more wider geometries in studying physical
phenomena.
| [
{
"created": "Thu, 27 Sep 2012 13:23:01 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Nov 2012 10:39:04 GMT",
"version": "v2"
},
{
"created": "Wed, 7 Nov 2012 07:37:20 GMT",
"version": "v3"
}
] | 2012-11-08 | [
[
"Wanas",
"M. I.",
""
],
[
"Hassan",
"H. A.",
""
]
] | The field equation of orthodox general relativity are written in the context of a geometry with non-vanishing torsion, the Absolute Parallelism (AP) geometry. An AP-structure, with homogeneity and isotropy, is used for cosmological applications. The resulting dynamical equations are those of FRW-Standard cosmology, which have many problems e.g. singularity, particle horizons, ...etc. We suggest a new scheme for investigating the effect of torsion on the dynamics of FRW-Cosmology, without changing the basic structure of general relativity. It is shown that some of these problems will disappear if the torsion, associated with AP-structure used, is inserted in to the dynamical equations. Diagnose shows that problems arise when GR is written in the context of a geometry with vanishing torsion, the Riemannian geometry. This reflects the importance of using more wider geometries in studying physical phenomena. |
1604.03662 | Lijing Shao | Lijing Shao, Norbert Wex | Tests of gravitational symmetries with radio pulsars | 23 pages, 9 figures. Invited review article, minor modifications to
match published version | Science China Physics, Mechanics & Astronomy 59, 699501 (2016) | 10.1007/s11433-016-0087-6 | null | gr-qc astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Symmetries play important roles in modern theories of physical laws. In this
paper, we review several experimental tests of important symmetries associated
with the gravitational interaction, including the universality of free fall for
self-gravitating bodies, time-shift symmetry in the gravitational constant,
local position invariance and local Lorentz invariance of gravity, and
spacetime translational symmetries. Recent experimental explorations for
post-Newtonian gravity are discussed, of which, those from pulsar astronomy are
highlighted. All of these tests, of very different aspects of gravity theories,
at very different length scales, favor to very high precision the predictions
of the strong equivalence principle (SEP) and, in particular, general
relativity which embodies SEP completely. As the founding principles of
gravity, these symmetries are motivated to be promoted to even stricter tests
in future.
| [
{
"created": "Wed, 13 Apr 2016 05:47:19 GMT",
"version": "v1"
},
{
"created": "Sat, 23 Jul 2016 13:46:51 GMT",
"version": "v2"
}
] | 2016-07-26 | [
[
"Shao",
"Lijing",
""
],
[
"Wex",
"Norbert",
""
]
] | Symmetries play important roles in modern theories of physical laws. In this paper, we review several experimental tests of important symmetries associated with the gravitational interaction, including the universality of free fall for self-gravitating bodies, time-shift symmetry in the gravitational constant, local position invariance and local Lorentz invariance of gravity, and spacetime translational symmetries. Recent experimental explorations for post-Newtonian gravity are discussed, of which, those from pulsar astronomy are highlighted. All of these tests, of very different aspects of gravity theories, at very different length scales, favor to very high precision the predictions of the strong equivalence principle (SEP) and, in particular, general relativity which embodies SEP completely. As the founding principles of gravity, these symmetries are motivated to be promoted to even stricter tests in future. |
gr-qc/9210011 | null | Chris J. Isham | Canonical Quantum Gravity and the Problem of Time | 125 pages of LaTeX output | null | null | Imperial/TP/91-92/25 | gr-qc | null | This is the write-up of my lectures at the NATO Summer School held in
Salamanca in June 1992. The paper deals with the problem of time in quantum
gravity. All the major schemes are reviewed. Please note that the paper is in
two parts for ease of email transmission; this is part 1. The mailer from gr-qc
may further subdivide these two sections.
| [
{
"created": "Wed, 21 Oct 1992 14:54:51 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Isham",
"Chris J.",
""
]
] | This is the write-up of my lectures at the NATO Summer School held in Salamanca in June 1992. The paper deals with the problem of time in quantum gravity. All the major schemes are reviewed. Please note that the paper is in two parts for ease of email transmission; this is part 1. The mailer from gr-qc may further subdivide these two sections. |
gr-qc/0107070 | Abhik Kumar Sanyal | A.K.Sanyal and B.Modak | Quantum Cosmology With R+R^2 Gravity | 8 pages, Latex2e | Class.Quant.Grav.19:515-526,2002 | 10.1088/0264-9381/19/3/307 | null | gr-qc | null | Canonical quantization of an action containing curvature squared term
requires introduction of an auxiliary variable. Boulware etal[1] prescribed a
technique to choose such a variable, by taking derivative of an action with
respect to the highest derivative of the field variable, present in the
action.It has been shown that[2] this technique can even be applied in
situations where introduction of auxiliary variables are not at all required,
leading to wrong Wheeler-deWitt equation. It has also been pointed out that[2]
Boulware etal's[1] prescription should be taken up only after removing all
removable total derivative terms from the action. Once this is done only a
unique description of quantum dynamics would emerge. For curvature squared term
this technique yields, for the first time, a quantum mechanical probability
interpretation of quantum cosmology, and an effective potential, whose
extremization leads to Einstein's equation. We conclude that Einstein-Hilbert
action should essentially be modified by at least a curvature squared term to
get a quantum mechanical formulation of quantuum cosmology and hence extend our
previous work[2] for such an action along with a scalar field.
| [
{
"created": "Sat, 21 Jul 2001 08:27:12 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Sanyal",
"A. K.",
""
],
[
"Modak",
"B.",
""
]
] | Canonical quantization of an action containing curvature squared term requires introduction of an auxiliary variable. Boulware etal[1] prescribed a technique to choose such a variable, by taking derivative of an action with respect to the highest derivative of the field variable, present in the action.It has been shown that[2] this technique can even be applied in situations where introduction of auxiliary variables are not at all required, leading to wrong Wheeler-deWitt equation. It has also been pointed out that[2] Boulware etal's[1] prescription should be taken up only after removing all removable total derivative terms from the action. Once this is done only a unique description of quantum dynamics would emerge. For curvature squared term this technique yields, for the first time, a quantum mechanical probability interpretation of quantum cosmology, and an effective potential, whose extremization leads to Einstein's equation. We conclude that Einstein-Hilbert action should essentially be modified by at least a curvature squared term to get a quantum mechanical formulation of quantuum cosmology and hence extend our previous work[2] for such an action along with a scalar field. |
gr-qc/0302106 | Kunihito Ioka | Kunihito Ioka, Misao Sasaki | Grad-Shafranov equation in noncircular stationary axisymmetric
spacetimes | 17 pages, accepted for publication in Physical Review D, proof
corrections added | Phys.Rev.D67:124026,2003 | 10.1103/PhysRevD.67.124026 | null | gr-qc astro-ph | null | A formulation is developed for general relativistic ideal
magnetohydrodynamics in stationary axisymmetric spacetimes. We reduce basic
equations to a single second-order partial differential equation, the so-called
Grad-Shafranov (GS) equation. Our formulation is most general in the sense that
it is applicable even when a stationary axisymmetric spacetime is noncircular,
that is, even when it is impossible to foliate a spacetime with two orthogonal
families of two-surfaces. The GS equation for noncircular spacetimes is crucial
for the study of relativistic stars with a toroidal magnetic field or
meridional flow, such as magnetars, since the existence of a toroidal field or
meridional flow violates the circularity of a spacetime. We also derive the
wind equation in noncircular spacetimes, and discuss various limits of the GS
equation.
| [
{
"created": "Wed, 26 Feb 2003 10:18:38 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Mar 2003 00:54:37 GMT",
"version": "v2"
},
{
"created": "Sat, 19 Apr 2003 10:31:48 GMT",
"version": "v3"
},
{
"created": "Fri, 2 May 2003 11:38:51 GMT",
"version": "v4"
},
{
"created": "Thu, 8 May 2003 01:10:19 GMT",
"version": "v5"
},
{
"created": "Mon, 8 Sep 2003 04:38:28 GMT",
"version": "v6"
}
] | 2009-10-09 | [
[
"Ioka",
"Kunihito",
""
],
[
"Sasaki",
"Misao",
""
]
] | A formulation is developed for general relativistic ideal magnetohydrodynamics in stationary axisymmetric spacetimes. We reduce basic equations to a single second-order partial differential equation, the so-called Grad-Shafranov (GS) equation. Our formulation is most general in the sense that it is applicable even when a stationary axisymmetric spacetime is noncircular, that is, even when it is impossible to foliate a spacetime with two orthogonal families of two-surfaces. The GS equation for noncircular spacetimes is crucial for the study of relativistic stars with a toroidal magnetic field or meridional flow, such as magnetars, since the existence of a toroidal field or meridional flow violates the circularity of a spacetime. We also derive the wind equation in noncircular spacetimes, and discuss various limits of the GS equation. |
gr-qc/9305019 | null | A.A. Starobinsky | New Restrictions on Spatial Topology of the Universe from Microwave
Background Temperature Fluctuations | 4 pages, report LANDAU-93-04/GR-1 | JETP Lett. 57 (1993) 622-625 | null | null | gr-qc astro-ph | null | If the Universe has the topology of a 3-torus ($T^3$), then it follows from
recent data on large-scale temperature fluctuations $\Delta T/T$ of the cosmic
microwave background that either the minimal size of the torus is at least of
the order of the present cosmological horizon, or the large-scale $\Delta T/T$
pattern should have a symmetry plane (in case of the effective $T^1$ topology)
or a symmetry axis (in case of the effective $T^2$ topology), the latter
possibility being probably excluded by the data.
| [
{
"created": "Sun, 23 May 1993 09:32:58 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Starobinsky",
"A. A.",
""
]
] | If the Universe has the topology of a 3-torus ($T^3$), then it follows from recent data on large-scale temperature fluctuations $\Delta T/T$ of the cosmic microwave background that either the minimal size of the torus is at least of the order of the present cosmological horizon, or the large-scale $\Delta T/T$ pattern should have a symmetry plane (in case of the effective $T^1$ topology) or a symmetry axis (in case of the effective $T^2$ topology), the latter possibility being probably excluded by the data. |
2306.12793 | Bobur Turimov | Bobur Turimov and Igor Smolyaninov | Curved spacetime as a dispersive multiferroic medium for an
electromagnetic wave: polarization and magnetization vectors in the
Schwarzschild spacetime | 11 pages, 3 figures, to be accepted to Chinese Journal of Physics | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study one of the interesting properties of the electromagnetic wave
propagation in the curved Schwarzschild background spacetime in the framework
of general relativity (GR). The electromagnetic wave equation has been derived
from vacuum general relativistic Maxwell's equations. It is shown that the
solutions for the electromagnetic field can be expanded in the spherical
harmonic functions and all components of the electromagnetic fields can be
expressed in terms of two radial profile functions. These radial profile
functions can be expressed in terms of the confluent Heun function. The
calculated behaviour of the electric and magnetic susceptibilities near the
event horizon appears to be similar to the susceptibilities of multiferroic
materials near phase transition. The Curie temperature of this phase transition
appears to coincide with the Hawking temperature.
| [
{
"created": "Thu, 22 Jun 2023 10:49:07 GMT",
"version": "v1"
}
] | 2023-06-23 | [
[
"Turimov",
"Bobur",
""
],
[
"Smolyaninov",
"Igor",
""
]
] | We study one of the interesting properties of the electromagnetic wave propagation in the curved Schwarzschild background spacetime in the framework of general relativity (GR). The electromagnetic wave equation has been derived from vacuum general relativistic Maxwell's equations. It is shown that the solutions for the electromagnetic field can be expanded in the spherical harmonic functions and all components of the electromagnetic fields can be expressed in terms of two radial profile functions. These radial profile functions can be expressed in terms of the confluent Heun function. The calculated behaviour of the electric and magnetic susceptibilities near the event horizon appears to be similar to the susceptibilities of multiferroic materials near phase transition. The Curie temperature of this phase transition appears to coincide with the Hawking temperature. |
0808.2025 | F\'abio Dahia | F. Dahia, C. Romero, M. A. S. Cruz | Effective Field Equations of Brane-Induced Electromagnetism | null | J.Math.Phys.49:112501,2008 | 10.1063/1.3019866 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using a covariant embedding formalism, we find the effective field equations
for the Electromagnetism that emerge on branes in the context of
Dvali-Gabadadze-Porrati (DGP) braneworld scenario. Our treatment is essentially
geometrical. We start with Maxwell equations in five-dimensions and project
them into an arbitrary brane. The formalism is quite general and allows us to
consider curved bulk spaces and curved branes whose tension is not necessarily
null. The kinetic electromagnetic term induced on the world volume of the
brane, proper of DGP models, is incorporated in this formulation by means of an
appropriate match condition. We also give an estimate of each term of the
effective field equations and determine the domain in which the
four-dimensional Maxwell equations can be recovered in the brane.
| [
{
"created": "Thu, 14 Aug 2008 16:42:34 GMT",
"version": "v1"
}
] | 2008-12-18 | [
[
"Dahia",
"F.",
""
],
[
"Romero",
"C.",
""
],
[
"Cruz",
"M. A. S.",
""
]
] | Using a covariant embedding formalism, we find the effective field equations for the Electromagnetism that emerge on branes in the context of Dvali-Gabadadze-Porrati (DGP) braneworld scenario. Our treatment is essentially geometrical. We start with Maxwell equations in five-dimensions and project them into an arbitrary brane. The formalism is quite general and allows us to consider curved bulk spaces and curved branes whose tension is not necessarily null. The kinetic electromagnetic term induced on the world volume of the brane, proper of DGP models, is incorporated in this formulation by means of an appropriate match condition. We also give an estimate of each term of the effective field equations and determine the domain in which the four-dimensional Maxwell equations can be recovered in the brane. |
2301.13228 | Silvia Gasparotto | Silvia Gasparotto, Rodrigo Vicente, Diego Blas, Alexander C. Jenkins,
Enrico Barausse | Can gravitational-wave memory help constrain binary black-hole
parameters? A LISA case study | 16 pages, comments are welcomed | null | 10.1103/PhysRevD.107.124033 | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | Besides the transient effect, the passage of a gravitational wave also causes
a persistent displacement in the relative position of an interferometer's test
masses through the \emph{nonlinear memory effect}. This effect is generated by
the gravitational backreaction of the waves themselves, and encodes additional
information about the source. In this work, we explore the implications of
using this information for the parameter estimation of massive binary black
holes with LISA. Based on a Fisher analysis for nonprecessing black hole
binaries, our results show that the memory can help to reduce the degeneracy
between the luminosity distance and the inclination for binaries observed only
for a short time ($\sim$~few hours) before merger. To assess how many such
short signals will be detected, we utilized state-of-the-art predictions for
the population of massive black hole binaries and models for the gaps expected
in the LISA data. We forecast from tens to few hundreds of binaries with
observable memory, but only~$\sim \mathcal{O}(0.1)$ events in 4 years for which
the memory helps to reduce the degeneracy between distance and inclination.
Based on this, we conclude that the new information from the nonlinear memory,
while promising for testing general relativity in the strong field regime, has
probably a limited impact on further constraining the uncertainty on massive
black hole binary parameters with LISA.
| [
{
"created": "Mon, 30 Jan 2023 19:00:15 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Jun 2023 09:38:55 GMT",
"version": "v2"
}
] | 2023-06-29 | [
[
"Gasparotto",
"Silvia",
""
],
[
"Vicente",
"Rodrigo",
""
],
[
"Blas",
"Diego",
""
],
[
"Jenkins",
"Alexander C.",
""
],
[
"Barausse",
"Enrico",
""
]
] | Besides the transient effect, the passage of a gravitational wave also causes a persistent displacement in the relative position of an interferometer's test masses through the \emph{nonlinear memory effect}. This effect is generated by the gravitational backreaction of the waves themselves, and encodes additional information about the source. In this work, we explore the implications of using this information for the parameter estimation of massive binary black holes with LISA. Based on a Fisher analysis for nonprecessing black hole binaries, our results show that the memory can help to reduce the degeneracy between the luminosity distance and the inclination for binaries observed only for a short time ($\sim$~few hours) before merger. To assess how many such short signals will be detected, we utilized state-of-the-art predictions for the population of massive black hole binaries and models for the gaps expected in the LISA data. We forecast from tens to few hundreds of binaries with observable memory, but only~$\sim \mathcal{O}(0.1)$ events in 4 years for which the memory helps to reduce the degeneracy between distance and inclination. Based on this, we conclude that the new information from the nonlinear memory, while promising for testing general relativity in the strong field regime, has probably a limited impact on further constraining the uncertainty on massive black hole binary parameters with LISA. |
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