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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2108.11642 | Brett Bochner | Brett Bochner | Electromagnetic wave propagation in general Kasner-like metrics | 32 pages, 1 figure; Further developments of research presented at the
22nd International Conference on General Relativity and Gravitation | Int. J. Mod. Phys. D (IJMPD) Vol. 31, No. 13, 2230016 (2022) | 10.1142/S0218271822300166 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | The curved spacetime Maxwell equations are applied to the anisotropically
expanding Kasner metrics. Using the application of vector identities we derive
2$^\textrm{nd}$-order differential wave equations for the electromagnetic field
components; through this explicit derivation, we find that the
2$^\textrm{nd}$-order wave equations are not uncoupled for the various
components (as previously assumed), but that gravitationally-induced coupling
between the electric and magnetic field components is generated directly by the
anisotropy of the expansion. The lack of such coupling terms in the wave
equations from several prior studies may indicate a generally incomplete
understanding of the evolution of electromagnetic energy in anisotropic
cosmologies. Uncoupling the field components requires the derivation of a
4$^\textrm{th}$-order wave equation, which we obtain for Kasner-like metrics
with generalized expansion/contraction rate indices. For the axisymmetric
Kasner case, $(p_{1}, p_{2}, p_{3}) = (1,0,0)$, we obtain exact field solutions
(for general propagation wavevectors), half of which appear not to have been
found before in previous studies. For the other axisymmetric Kasner case,
$\{p_{1}, p_{2}, p_{3}\} = \{(-1/3),(2/3),(2/3)\}$, we use numerical methods to
demonstrate the explicit violation of the geometric optics approximation at
early times, showing the physical phase velocity of the wave to be inhibited
towards the initial singularity, with $v \rightarrow 0$ as $t \rightarrow 0$.
| [
{
"created": "Thu, 26 Aug 2021 08:15:35 GMT",
"version": "v1"
}
] | 2022-11-08 | [
[
"Bochner",
"Brett",
""
]
] | The curved spacetime Maxwell equations are applied to the anisotropically expanding Kasner metrics. Using the application of vector identities we derive 2$^\textrm{nd}$-order differential wave equations for the electromagnetic field components; through this explicit derivation, we find that the 2$^\textrm{nd}$-order wave equations are not uncoupled for the various components (as previously assumed), but that gravitationally-induced coupling between the electric and magnetic field components is generated directly by the anisotropy of the expansion. The lack of such coupling terms in the wave equations from several prior studies may indicate a generally incomplete understanding of the evolution of electromagnetic energy in anisotropic cosmologies. Uncoupling the field components requires the derivation of a 4$^\textrm{th}$-order wave equation, which we obtain for Kasner-like metrics with generalized expansion/contraction rate indices. For the axisymmetric Kasner case, $(p_{1}, p_{2}, p_{3}) = (1,0,0)$, we obtain exact field solutions (for general propagation wavevectors), half of which appear not to have been found before in previous studies. For the other axisymmetric Kasner case, $\{p_{1}, p_{2}, p_{3}\} = \{(-1/3),(2/3),(2/3)\}$, we use numerical methods to demonstrate the explicit violation of the geometric optics approximation at early times, showing the physical phase velocity of the wave to be inhibited towards the initial singularity, with $v \rightarrow 0$ as $t \rightarrow 0$. |
1907.11080 | Andrea Geralico | Donato Bini, Andrea Geralico | New gravitational self-force analytical results for eccentric equatorial
orbits around a Kerr black hole: redshift invariant | 15 pages, revtex macros | Phys. Rev. D 100, 104002 (2019) | 10.1103/PhysRevD.100.104002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Detweiler-Barack-Sago redshift function for particles moving along
slightly eccentric equatorial orbits around a Kerr black hole is currently
known up to the second order in eccentricity, second order in spin parameter,
and the 8.5 post-Newtonian order. We improve the analytical computation of such
a gauge-invariant quantity by including terms up to the fourth order in
eccentricity at the same post-Newtonian approximation level. We also check that
our results agrees with the corresponding post-Newtonian expectation of the
same quantity, calculated by using the currently known Hamiltonian for spinning
binaries.
| [
{
"created": "Tue, 23 Jul 2019 20:28:40 GMT",
"version": "v1"
}
] | 2019-11-13 | [
[
"Bini",
"Donato",
""
],
[
"Geralico",
"Andrea",
""
]
] | The Detweiler-Barack-Sago redshift function for particles moving along slightly eccentric equatorial orbits around a Kerr black hole is currently known up to the second order in eccentricity, second order in spin parameter, and the 8.5 post-Newtonian order. We improve the analytical computation of such a gauge-invariant quantity by including terms up to the fourth order in eccentricity at the same post-Newtonian approximation level. We also check that our results agrees with the corresponding post-Newtonian expectation of the same quantity, calculated by using the currently known Hamiltonian for spinning binaries. |
2307.09632 | Mitja Fridman | Saurya Das, Mitja Fridman, Gaetano Lambiase | General Formalism of the Quantum Equivalence Principle | 14 pages | Commun. Phys. 6, 198 (2023) | 10.1038/s42005-023-01306-w | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A consistent theory of quantum gravity will require a fully quantum
formulation of the classical equivalence principle. Such a formulation has been
recently proposed in terms of the equality of the rest, inertial and
gravitational mass operators, and for non-relativistic particles in a weak
gravitational field. In this work, we propose a generalization to a fully
relativistic formalism of the quantum equivalence principle, valid for all
background space-times, as well as for massive bosons and fermions. The
principle is trivially satisfied for massless particles. We show that if the
equivalence principle is broken at the quantum level, it implies the
modification of the standard Lorentz transformations in flat space-time and a
corresponding modification of the metric in curved space-time by the different
mass ratios. In other words, the observed geometry would effectively depend on
the properties of the test particle. Testable predictions of potential
violations of the quantum equivalence principle are proposed.
| [
{
"created": "Tue, 18 Jul 2023 20:53:10 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Aug 2023 21:26:15 GMT",
"version": "v2"
}
] | 2023-08-03 | [
[
"Das",
"Saurya",
""
],
[
"Fridman",
"Mitja",
""
],
[
"Lambiase",
"Gaetano",
""
]
] | A consistent theory of quantum gravity will require a fully quantum formulation of the classical equivalence principle. Such a formulation has been recently proposed in terms of the equality of the rest, inertial and gravitational mass operators, and for non-relativistic particles in a weak gravitational field. In this work, we propose a generalization to a fully relativistic formalism of the quantum equivalence principle, valid for all background space-times, as well as for massive bosons and fermions. The principle is trivially satisfied for massless particles. We show that if the equivalence principle is broken at the quantum level, it implies the modification of the standard Lorentz transformations in flat space-time and a corresponding modification of the metric in curved space-time by the different mass ratios. In other words, the observed geometry would effectively depend on the properties of the test particle. Testable predictions of potential violations of the quantum equivalence principle are proposed. |
2402.18882 | Anirban Chatterjee | Anirban Chatterjee, Abhijit Bandyopadhyay and Debasish Majumdar | Exploring the evolution of structure growth in the universe with
field-fluid interactions through dynamical stability analysis | 23 pages, 2 tables and 6 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We investigate an interacting quintessence dark energy - dark matter scenario
and its impact on structure formation by analyzing the evolution of scalar
perturbations. The interaction is introduced by incorporating a non-zero source
term into the continuity equations of the two sectors (with opposite signs),
modeled as $\bar{Q}_0 \equiv \alpha\bar{\rho}_{\rm m}(H + \kappa\dot{\phi})$.
The coupling parameter $\alpha$ and the parameter $\lambda$ involved in
quintessence potential $V(\phi) = V_0e^{-\lambda\kappa\phi}$, play crucial
roles in governing the dynamics of evolution examined within the present
framework. The cosmic evolution, within this context, is depicted as a
first-order autonomous system of equations involving appropriately chosen
dynamical variables. We analyzed the associated stability characteristics and
growth rate of perturbations and obtained domains in the ($\alpha-\lambda$)
parameter space for which fixed points can exhibit stable and non-phantom
accelerating solutions. Depending on its magnitude, the coupling parameter
$\alpha$ has the potential to change the characteristics of certain critical
points, altering them from attractors to repellers. This model effectively
captures the evolutionary features of the universe across its various phases at
both the background and perturbation levels. The issue of cosmic coincidence
can also be addressed within the framework of this model. We also observed that
for a moderate strength of coupling, the growth rate of matter perturbation
extends into the distant future.
| [
{
"created": "Thu, 29 Feb 2024 05:59:55 GMT",
"version": "v1"
}
] | 2024-03-01 | [
[
"Chatterjee",
"Anirban",
""
],
[
"Bandyopadhyay",
"Abhijit",
""
],
[
"Majumdar",
"Debasish",
""
]
] | We investigate an interacting quintessence dark energy - dark matter scenario and its impact on structure formation by analyzing the evolution of scalar perturbations. The interaction is introduced by incorporating a non-zero source term into the continuity equations of the two sectors (with opposite signs), modeled as $\bar{Q}_0 \equiv \alpha\bar{\rho}_{\rm m}(H + \kappa\dot{\phi})$. The coupling parameter $\alpha$ and the parameter $\lambda$ involved in quintessence potential $V(\phi) = V_0e^{-\lambda\kappa\phi}$, play crucial roles in governing the dynamics of evolution examined within the present framework. The cosmic evolution, within this context, is depicted as a first-order autonomous system of equations involving appropriately chosen dynamical variables. We analyzed the associated stability characteristics and growth rate of perturbations and obtained domains in the ($\alpha-\lambda$) parameter space for which fixed points can exhibit stable and non-phantom accelerating solutions. Depending on its magnitude, the coupling parameter $\alpha$ has the potential to change the characteristics of certain critical points, altering them from attractors to repellers. This model effectively captures the evolutionary features of the universe across its various phases at both the background and perturbation levels. The issue of cosmic coincidence can also be addressed within the framework of this model. We also observed that for a moderate strength of coupling, the growth rate of matter perturbation extends into the distant future. |
2103.01816 | Karim Van Aelst | Karim Van Aelst | Note on equatorial geodesics in circular spacetimes | 18 pages, 5 figures, version published in CQG | Class. Quantum Grav. 37 207001 (2020) | 10.1088/1361-6382/aba80c | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | General results on equatorial geodesics are exposed in the case of circular
spacetimes featuring an equatorial reflection symmetry. The way the geodesic
equation equivalently rewrites in terms of an effective potential is explicitly
recalled for circular and non-circular equatorial geodesics. This provides a
practical tool to discuss their stability. Statements are illustrated in Kerr
spacetime.
| [
{
"created": "Tue, 2 Mar 2021 15:46:14 GMT",
"version": "v1"
}
] | 2021-03-03 | [
[
"Van Aelst",
"Karim",
""
]
] | General results on equatorial geodesics are exposed in the case of circular spacetimes featuring an equatorial reflection symmetry. The way the geodesic equation equivalently rewrites in terms of an effective potential is explicitly recalled for circular and non-circular equatorial geodesics. This provides a practical tool to discuss their stability. Statements are illustrated in Kerr spacetime. |
2212.11648 | Maria Shubina | Maria Shubina | Exact analytical vacuum solutions of $ R^n $-gravity model depending on
two variables | 19 pages, 8 figures | null | 10.1016/j.aop.2023.169245 | null | gr-qc math-ph math.MP nlin.SI | http://creativecommons.org/licenses/by/4.0/ | In this paper we consider the metric power-law $f(R)\sim R^n $-gravity model
for the four-dimensional metric tensor depending on two coordinates. We obtain
exact analytical vacuum solutions for different values of $ n $. These
solutions contain both non-stationary configurations of the travelling wave
type and stationary ones, in particular, depending on one radial variable.
| [
{
"created": "Thu, 22 Dec 2022 12:32:47 GMT",
"version": "v1"
}
] | 2023-03-22 | [
[
"Shubina",
"Maria",
""
]
] | In this paper we consider the metric power-law $f(R)\sim R^n $-gravity model for the four-dimensional metric tensor depending on two coordinates. We obtain exact analytical vacuum solutions for different values of $ n $. These solutions contain both non-stationary configurations of the travelling wave type and stationary ones, in particular, depending on one radial variable. |
1502.06257 | Junbin Li | Junbin Li, Xi-Ping Zhu | Local existence in retarded time under a weak decay on complete null
cones | 30 pages. arXiv admin note: text overlap with arXiv:1406.0048 | null | 10.1007/s11425-015-5056-7 | null | gr-qc math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the previous paper \cite{L-Z}, for a characteristic problem with not
necessarily small initial data given on a complete null cone decaying like that
in the work \cite{Ch-K} of the stability of Minkowski spacetime by
Christodoulou and Klainerman, we proved the local existence in retarded time,
which means the solution to the vacuum Einstein equations exists in a uniform
future neighborhood, while the global existence in retarded time is the weak
cosmic censorship conjecture. In this paper, we prove that the local existence
in retarded time still holds when the data is assumed to decay slower, like
that in Bieri's work \cite{Bie} on the extension to the stability of Minkowski
spacetime. Such decay guarantees the existence of the limit of the Hawking mass
on the initial null cone, when approaching to infinity, in an optimal way.
| [
{
"created": "Sun, 22 Feb 2015 18:31:48 GMT",
"version": "v1"
}
] | 2016-01-20 | [
[
"Li",
"Junbin",
""
],
[
"Zhu",
"Xi-Ping",
""
]
] | In the previous paper \cite{L-Z}, for a characteristic problem with not necessarily small initial data given on a complete null cone decaying like that in the work \cite{Ch-K} of the stability of Minkowski spacetime by Christodoulou and Klainerman, we proved the local existence in retarded time, which means the solution to the vacuum Einstein equations exists in a uniform future neighborhood, while the global existence in retarded time is the weak cosmic censorship conjecture. In this paper, we prove that the local existence in retarded time still holds when the data is assumed to decay slower, like that in Bieri's work \cite{Bie} on the extension to the stability of Minkowski spacetime. Such decay guarantees the existence of the limit of the Hawking mass on the initial null cone, when approaching to infinity, in an optimal way. |
2107.08876 | Eleanor Hamilton | Eleanor Hamilton, Lionel London, Jonathan E. Thompson, Edward
Fauchon-Jones, Mark Hannam, Chinmay Kalaghatgi, Sebastian Khan, Francesco
Pannarale and Alex Vano-Vinuales | The final twist: A model of gravitational waves from precessing
black-hole binaries through merger and ringdown | 40 pages, 28 figures | null | 10.1103/PhysRevD.104.124027 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We present PhenomPNR, a frequency-domain phenomenological model of the
gravitational-wave (GW) signal from binary-black-hole mergers that is tuned to
numerical relativity (NR) simulations of precessing binaries. In many current
waveform models, e.g., the "Phenom" and "EOBNR" families that have been used
extensively to analyse LIGO-Virgo GW observations, analytic approximations are
used to add precession effects to models of non-precessing (aligned-spin)
binaries, and it is only the aligned-spin models that are fully tuned to NR
results. In PhenomPNR we incorporate precessing-binary NR results in two ways:
(i) we produce the first NR-tuned model of the signal-based precession dynamics
through merger and ringdown, and (ii) we extend a previous aligned-spin model,
PhenomD, to include the effects of misaligned spins on the signal in the
co-precessing frame. The NR calibration has been performed on 40 simulations of
binaries with mass ratios between 1:1 and 1:8, where the larger black hole has
a dimensionless spin magnitude of 0.4 or 0.8, and we choose five angles of spin
misalignment with the orbital angular momentum. PhenomPNR has a typical
mismatch accuracy within 0.1% up to mass-ratio 1:4, and within 1% up to
mass-ratio 1:8.
| [
{
"created": "Mon, 19 Jul 2021 13:48:09 GMT",
"version": "v1"
}
] | 2021-12-22 | [
[
"Hamilton",
"Eleanor",
""
],
[
"London",
"Lionel",
""
],
[
"Thompson",
"Jonathan E.",
""
],
[
"Fauchon-Jones",
"Edward",
""
],
[
"Hannam",
"Mark",
""
],
[
"Kalaghatgi",
"Chinmay",
""
],
[
"Khan",
"Sebastian",
""
],
[
"Pannarale",
"Francesco",
""
],
[
"Vano-Vinuales",
"Alex",
""
]
] | We present PhenomPNR, a frequency-domain phenomenological model of the gravitational-wave (GW) signal from binary-black-hole mergers that is tuned to numerical relativity (NR) simulations of precessing binaries. In many current waveform models, e.g., the "Phenom" and "EOBNR" families that have been used extensively to analyse LIGO-Virgo GW observations, analytic approximations are used to add precession effects to models of non-precessing (aligned-spin) binaries, and it is only the aligned-spin models that are fully tuned to NR results. In PhenomPNR we incorporate precessing-binary NR results in two ways: (i) we produce the first NR-tuned model of the signal-based precession dynamics through merger and ringdown, and (ii) we extend a previous aligned-spin model, PhenomD, to include the effects of misaligned spins on the signal in the co-precessing frame. The NR calibration has been performed on 40 simulations of binaries with mass ratios between 1:1 and 1:8, where the larger black hole has a dimensionless spin magnitude of 0.4 or 0.8, and we choose five angles of spin misalignment with the orbital angular momentum. PhenomPNR has a typical mismatch accuracy within 0.1% up to mass-ratio 1:4, and within 1% up to mass-ratio 1:8. |
2408.07036 | Karol Urba\'nski | Karol Urba\'nski | Visual relativistic mechanics | 8 pages, 9 figures | null | null | null | gr-qc physics.class-ph physics.ed-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Many formalisms of special relativity are shown in various textbooks.
However, even in those where the underlying geometry of Minkowski space is
emphasized, the visualisations are lacking. This article aims to remedy this by
expressing relativistic concepts in a visual manner, using the full power of
hyperbolic trigonometric functions. Minkowski diagrams in energy-momentum space
are used and then augmented in comparison with previous uses in literature by
direct usage of triangles in Minkowski space. As a proof-of-concept for the
advantages of this holistic approach, elegant new derivations of the
relativistic rocket equation and the relativistic Doppler effect are presented.
| [
{
"created": "Tue, 13 Aug 2024 17:02:20 GMT",
"version": "v1"
}
] | 2024-08-14 | [
[
"Urbański",
"Karol",
""
]
] | Many formalisms of special relativity are shown in various textbooks. However, even in those where the underlying geometry of Minkowski space is emphasized, the visualisations are lacking. This article aims to remedy this by expressing relativistic concepts in a visual manner, using the full power of hyperbolic trigonometric functions. Minkowski diagrams in energy-momentum space are used and then augmented in comparison with previous uses in literature by direct usage of triangles in Minkowski space. As a proof-of-concept for the advantages of this holistic approach, elegant new derivations of the relativistic rocket equation and the relativistic Doppler effect are presented. |
1710.06789 | Shinji Tsujikawa | Sachiko Kuroyanagi, Chunshan Lin, Misao Sasaki, Shinji Tsujikawa | Observational signatures of the parametric amplification of
gravitational waves during reheating after inflation | 17 pages, 8 figures | Phys. Rev. D 97, 023516 (2018) | 10.1103/PhysRevD.97.023516 | YITP-17-99 | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the evolution of Gravitational Waves (GWs) during and after
inflation as well as the resulting observational consequences in a
Lorentz-violating massive gravity theory with one scalar (inflaton) and two
tensor degrees of freedom. We consider two explicit examples of the tensor mass
$m_g$ that depends either on the inflaton field $\phi$ or on its time
derivative $\dot{\phi}$, both of which lead to parametric excitations of GWs
during reheating after inflation. The first example is Starobinsky's $R^2$
inflation model with a $\phi$-dependent $m_g$ and the second is a
low-energy-scale inflation model with a $\dot{\phi}$-dependent $m_g$. We
compute the energy density spectrum $\Omega_{\rm GW}(k)$ today of the GW
background. In the Starobinsky's model, we show that the GWs can be amplified
up to the detectable ranges of both CMB and DECIGO, but the bound from the big
bang nucleosynthesis is quite tight to limit the growth. In low-scale inflation
with a fast transition to the reheating stage driven by the potential
$V(\phi)=M^2 \phi^2/2$ around $\phi \approx M_{\rm pl}$ (where $M_{\rm pl}$ is
the reduced Planck mass), we find that the peak position of $\Omega_{\rm
GW}(k)$ induced by the parametric resonance can reach the sensitivity region of
advanced LIGO for the Hubble parameter of order 1 GeV at the end of inflation.
Thus, our massive gravity scenario offers exciting possibilities for probing
the physics of primordial GWs at various different frequencies.
| [
{
"created": "Wed, 18 Oct 2017 15:37:32 GMT",
"version": "v1"
},
{
"created": "Sat, 20 Jan 2018 00:30:13 GMT",
"version": "v2"
}
] | 2018-01-23 | [
[
"Kuroyanagi",
"Sachiko",
""
],
[
"Lin",
"Chunshan",
""
],
[
"Sasaki",
"Misao",
""
],
[
"Tsujikawa",
"Shinji",
""
]
] | We study the evolution of Gravitational Waves (GWs) during and after inflation as well as the resulting observational consequences in a Lorentz-violating massive gravity theory with one scalar (inflaton) and two tensor degrees of freedom. We consider two explicit examples of the tensor mass $m_g$ that depends either on the inflaton field $\phi$ or on its time derivative $\dot{\phi}$, both of which lead to parametric excitations of GWs during reheating after inflation. The first example is Starobinsky's $R^2$ inflation model with a $\phi$-dependent $m_g$ and the second is a low-energy-scale inflation model with a $\dot{\phi}$-dependent $m_g$. We compute the energy density spectrum $\Omega_{\rm GW}(k)$ today of the GW background. In the Starobinsky's model, we show that the GWs can be amplified up to the detectable ranges of both CMB and DECIGO, but the bound from the big bang nucleosynthesis is quite tight to limit the growth. In low-scale inflation with a fast transition to the reheating stage driven by the potential $V(\phi)=M^2 \phi^2/2$ around $\phi \approx M_{\rm pl}$ (where $M_{\rm pl}$ is the reduced Planck mass), we find that the peak position of $\Omega_{\rm GW}(k)$ induced by the parametric resonance can reach the sensitivity region of advanced LIGO for the Hubble parameter of order 1 GeV at the end of inflation. Thus, our massive gravity scenario offers exciting possibilities for probing the physics of primordial GWs at various different frequencies. |
1908.07504 | Henk Bart | Henk Bart | Quasi-local conserved charges in General Relativity | null | null | null | MPP-2019-179 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A general prescription for constructing quasi-local conserved quantities in
General Relativity is proposed. The construction is applied to BMS symmetry
generators in Newman-Unti gauge, so as to define quasi-local BMS charges. It is
argued that the zero mode of this BMS charge is a promising definition of
quasi-local energy.
| [
{
"created": "Tue, 20 Aug 2019 17:28:35 GMT",
"version": "v1"
}
] | 2019-08-21 | [
[
"Bart",
"Henk",
""
]
] | A general prescription for constructing quasi-local conserved quantities in General Relativity is proposed. The construction is applied to BMS symmetry generators in Newman-Unti gauge, so as to define quasi-local BMS charges. It is argued that the zero mode of this BMS charge is a promising definition of quasi-local energy. |
1907.03509 | B. S. Kandemir | B. S. Kandemir | Hairy BTZ black hole and its analogue model in graphene | null | null | 10.1016/j.aop.2019.168064 | null | gr-qc cond-mat.mes-hall | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain a novel exact analytical solution to Einstein-Maxwell-scalar
gravity with negative cosmological constant in (2+1)-dimensions. The scalar
field is minimally coupled to gravity and electromagnetism by the metric
ansatz. On the one hand, we first find analytical results for the real part of
quasinormal mode spectrum of a rotating hairy Ba\~{n}ados-Teitelboim-Zanelli
(BTZ) black hole by solving the associated Dirac equation through the
pseudo-Hermitian quantum mechanical tools within the framework of
discrete-basis-set method. We then show that, in the spinless case, these
quasinormal modes (QNMs) have equally spaced with respect to the related
azimuthal quantum number, while the spinning BTZ black hole with scalar hair
has Dirac-like unequally spaced discrete one. Moreover, the analytical results
for these QNMs found here are in excellent agreement with those found in the
literature for hairless BTZ black holes. On the other hand, we also develop an
analogue model for this hairy Banados-Teitelboim-Zanelli black hole in
graphene, by mapping it onto the hyperbolic pseudosphere surface with negative
curvature. The model not only offers to make some predictions for the
gravity-like phenomena in a curved graphene sheet but also paves the way for
reproducing black hole thermodynamics scenarios in two-dimensional topological
insulators.
| [
{
"created": "Mon, 8 Jul 2019 11:03:58 GMT",
"version": "v1"
}
] | 2020-01-29 | [
[
"Kandemir",
"B. S.",
""
]
] | We obtain a novel exact analytical solution to Einstein-Maxwell-scalar gravity with negative cosmological constant in (2+1)-dimensions. The scalar field is minimally coupled to gravity and electromagnetism by the metric ansatz. On the one hand, we first find analytical results for the real part of quasinormal mode spectrum of a rotating hairy Ba\~{n}ados-Teitelboim-Zanelli (BTZ) black hole by solving the associated Dirac equation through the pseudo-Hermitian quantum mechanical tools within the framework of discrete-basis-set method. We then show that, in the spinless case, these quasinormal modes (QNMs) have equally spaced with respect to the related azimuthal quantum number, while the spinning BTZ black hole with scalar hair has Dirac-like unequally spaced discrete one. Moreover, the analytical results for these QNMs found here are in excellent agreement with those found in the literature for hairless BTZ black holes. On the other hand, we also develop an analogue model for this hairy Banados-Teitelboim-Zanelli black hole in graphene, by mapping it onto the hyperbolic pseudosphere surface with negative curvature. The model not only offers to make some predictions for the gravity-like phenomena in a curved graphene sheet but also paves the way for reproducing black hole thermodynamics scenarios in two-dimensional topological insulators. |
gr-qc/9312026 | James E. Lidsey | James E. Lidsey | Solutions to the Wheeler-Dewitt Equation Inspired by the String
Effective Action | 21 pages of plain LaTeX, Fermilab-Pub-93/100-A | Class.Quant.Grav.11:1211-1224,1994 | 10.1088/0264-9381/11/5/009 | null | gr-qc | null | The Wheeler-DeWitt equation is derived from the bosonic sector of the
heterotic string effective action assuming a toroidal compactification. The
spatially closed, higher dimensional Friedmann-Robertson-Walker (FRW) cosmology
is investigated and a suitable change of variables rewrites the equation in a
canonical form. Real- and imaginary-phase exact solutions are found and a
method of successive approximations is employed to find more general power
series solutions. The quantum cosmology of the Bianchi IX universe is also
investigated and a class of exact solutions is found.
| [
{
"created": "Thu, 16 Dec 1993 16:03:10 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Lidsey",
"James E.",
""
]
] | The Wheeler-DeWitt equation is derived from the bosonic sector of the heterotic string effective action assuming a toroidal compactification. The spatially closed, higher dimensional Friedmann-Robertson-Walker (FRW) cosmology is investigated and a suitable change of variables rewrites the equation in a canonical form. Real- and imaginary-phase exact solutions are found and a method of successive approximations is employed to find more general power series solutions. The quantum cosmology of the Bianchi IX universe is also investigated and a class of exact solutions is found. |
1501.02187 | Arturo Stabile | A. Stabile, S. Capozziello | Post-Minkowskian Limit and Gravitational Waves solutions of Fourth Order
Gravity: a complete study | 10 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The post-Minkowskian limit and gravitational wave solutions for general
fourth-order gravity theories are discussed. Specifically, we consider a
Lagrangian with a generic function of curvature invariants $f(R,
R_{\alpha\beta}R^{\alpha\beta},
R_{\alpha\beta\gamma\delta}R^{\alpha\beta\gamma\delta})$. It is well known that
when dealing with General Relativity such an approach provides massless
spin-two waves as propagating degree of freedom of the gravitational field
while this theory implies other additional propagating modes in the gravity
spectra. We show that, in general, fourth order gravity, besides the standard
massless graviton is characterized by two further massive modes with a
finite-distance interaction. We find out the most general gravitational wave
solutions in terms of Green functions in vacuum and in presence of matter
sources. If an electromagnetic source is chosen, only the modes induced by
$R_{\alpha\beta}R^{\alpha\beta}$ are present, otherwise, for any $f(R)$ gravity
model, we have the complete analogy with tensor modes of General Relativity.
Polarizations and helicity states are classified in the hypothesis of plane
wave.
| [
{
"created": "Fri, 9 Jan 2015 16:02:19 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Apr 2015 22:24:41 GMT",
"version": "v2"
}
] | 2015-04-28 | [
[
"Stabile",
"A.",
""
],
[
"Capozziello",
"S.",
""
]
] | The post-Minkowskian limit and gravitational wave solutions for general fourth-order gravity theories are discussed. Specifically, we consider a Lagrangian with a generic function of curvature invariants $f(R, R_{\alpha\beta}R^{\alpha\beta}, R_{\alpha\beta\gamma\delta}R^{\alpha\beta\gamma\delta})$. It is well known that when dealing with General Relativity such an approach provides massless spin-two waves as propagating degree of freedom of the gravitational field while this theory implies other additional propagating modes in the gravity spectra. We show that, in general, fourth order gravity, besides the standard massless graviton is characterized by two further massive modes with a finite-distance interaction. We find out the most general gravitational wave solutions in terms of Green functions in vacuum and in presence of matter sources. If an electromagnetic source is chosen, only the modes induced by $R_{\alpha\beta}R^{\alpha\beta}$ are present, otherwise, for any $f(R)$ gravity model, we have the complete analogy with tensor modes of General Relativity. Polarizations and helicity states are classified in the hypothesis of plane wave. |
2203.13252 | Meng-Xiang Lin | Jose Maria Ezquiaga, Wayne Hu, Macarena Lagos, Meng-Xiang Lin, Fei Xu | Modified gravitational wave propagation with higher modes and its
degeneracies with lensing | 32 pages, 6 figures. Match the published version | Journal of Cosmology and Astroparticle Physics, Volume 2022, Issue
08, id.016, 33 pp | 10.1088/1475-7516/2022/08/016 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Low-energy alternatives to General Relativity (GR) generically modify the
phase of gravitational waves (GWs) during their propagation. As detector
sensitivities increase, it becomes key to understand how these modifications
affect the GW higher modes and to disentangle possible degeneracies with
astrophysical phenomena. We apply a general formalism -- the WKB approach --
for solving analytically wave propagation in the spatial domain with a modified
dispersion relation (MDR). We compare this WKB approach to applying a
stationary phase approximation (SPA) in the temporal domain with time delays
associated to the group or particle velocity. To this end, we extend the SPA to
generic signals with higher modes, keeping careful track of reference phases
and arrival times. We find that the WKB approach coincides with the SPA using
the group velocity, in agreement with the principles of wave propagation. We
then explore the degeneracies between a GW propagation with an MDR and a
strongly-lensed GW in GR, since the latter can introduce a
frequency-independent phase shift which is not degenerate with source
parameters in the presence of higher modes. We find that for a particular MDR
there is an exact degeneracy for wave propagation, unlike with the SPA for
particle propagation. For the other cases, we search for the values of the MDR
parameters that minimize the $\chi^2$ and conclude that strongly-lensed GR GWs
could be misinterpreted as GWs in modified gravity. Future MDR constraints with
higher mode GWs should include the possibility of frequency-independent phase
shifts, allowing for the identification of modified gravity and strong lensing
distortions at the same time.
| [
{
"created": "Thu, 24 Mar 2022 17:59:05 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Aug 2022 22:56:13 GMT",
"version": "v2"
}
] | 2022-08-17 | [
[
"Ezquiaga",
"Jose Maria",
""
],
[
"Hu",
"Wayne",
""
],
[
"Lagos",
"Macarena",
""
],
[
"Lin",
"Meng-Xiang",
""
],
[
"Xu",
"Fei",
""
]
] | Low-energy alternatives to General Relativity (GR) generically modify the phase of gravitational waves (GWs) during their propagation. As detector sensitivities increase, it becomes key to understand how these modifications affect the GW higher modes and to disentangle possible degeneracies with astrophysical phenomena. We apply a general formalism -- the WKB approach -- for solving analytically wave propagation in the spatial domain with a modified dispersion relation (MDR). We compare this WKB approach to applying a stationary phase approximation (SPA) in the temporal domain with time delays associated to the group or particle velocity. To this end, we extend the SPA to generic signals with higher modes, keeping careful track of reference phases and arrival times. We find that the WKB approach coincides with the SPA using the group velocity, in agreement with the principles of wave propagation. We then explore the degeneracies between a GW propagation with an MDR and a strongly-lensed GW in GR, since the latter can introduce a frequency-independent phase shift which is not degenerate with source parameters in the presence of higher modes. We find that for a particular MDR there is an exact degeneracy for wave propagation, unlike with the SPA for particle propagation. For the other cases, we search for the values of the MDR parameters that minimize the $\chi^2$ and conclude that strongly-lensed GR GWs could be misinterpreted as GWs in modified gravity. Future MDR constraints with higher mode GWs should include the possibility of frequency-independent phase shifts, allowing for the identification of modified gravity and strong lensing distortions at the same time. |
2308.16791 | Sam E. Brady | Sam E. Brady, Llibert Arest\'e Sal\'o, Katy Clough, Pau Figueras,
Annamalai P. S | Solving the initial conditions problem for modified gravity theories | 9 pages, 4 figures, comments welcome! | null | 10.1103/PhysRevD.108.104022 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Modified gravity theories such as Einstein scalar Gauss Bonnet (EsGB) contain
higher derivative terms in the spacetime curvature in their action, which
results in modifications to the Hamiltonian and momentum constraints of the
theory. In principle, such modifications may affect the principal part of the
operator in the resulting elliptic equations, and so further complicate the
already highly non-linear, coupled constraints that apply to the initial data
in numerical relativity simulations of curved spacetimes. However, since these
are effective field theories, we expect the additional curvature terms to be
small, which motivates treating them simply as an additional source in the
constraints, and iterating to find a solution to the full problem. In this work
we implement and test a modification to the CTT/CTTK methods of solving the
constraints for the case of the most general four derivative, parity invariant
scalar-tensor theory, and show that solutions can be found in both
asymptotically flat/black hole and periodic/cosmological spacetimes, even up to
couplings of order unity in the theory. Such methods will allow for numerical
investigations of a much broader class of initial data than has previously been
possible in these theories, and should be straightforward to extend to similar
models in the Horndeski class.
| [
{
"created": "Thu, 31 Aug 2023 15:08:09 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Nov 2023 10:17:40 GMT",
"version": "v2"
}
] | 2023-12-01 | [
[
"Brady",
"Sam E.",
""
],
[
"Saló",
"Llibert Aresté",
""
],
[
"Clough",
"Katy",
""
],
[
"Figueras",
"Pau",
""
],
[
"S",
"Annamalai P.",
""
]
] | Modified gravity theories such as Einstein scalar Gauss Bonnet (EsGB) contain higher derivative terms in the spacetime curvature in their action, which results in modifications to the Hamiltonian and momentum constraints of the theory. In principle, such modifications may affect the principal part of the operator in the resulting elliptic equations, and so further complicate the already highly non-linear, coupled constraints that apply to the initial data in numerical relativity simulations of curved spacetimes. However, since these are effective field theories, we expect the additional curvature terms to be small, which motivates treating them simply as an additional source in the constraints, and iterating to find a solution to the full problem. In this work we implement and test a modification to the CTT/CTTK methods of solving the constraints for the case of the most general four derivative, parity invariant scalar-tensor theory, and show that solutions can be found in both asymptotically flat/black hole and periodic/cosmological spacetimes, even up to couplings of order unity in the theory. Such methods will allow for numerical investigations of a much broader class of initial data than has previously been possible in these theories, and should be straightforward to extend to similar models in the Horndeski class. |
gr-qc/0404091 | T. Roy Choudhury | T. Roy Choudhury, T. Padmanabhan | Concept of temperature in multi-horizon spacetimes: Analysis of
Schwarzschild-De Sitter metric | 12 pages | Gen.Rel.Grav.39:1789-1811,2007 | 10.1007/s10714-007-0489-0 | null | gr-qc astro-ph hep-th | null | In case of spacetimes with single horizon, there exist several
well-established procedures for relating the surface gravity of the horizon to
a thermodynamic temperature. Such procedures, however, cannot be extended in a
straightforward manner when a spacetime has multiple horizons. In particular,
it is not clear whether there exists a notion of global temperature
characterizing the multi-horizon spacetimes. We examine the conditions under
which a global temperature can exist for a spacetime with two horizons using
the example of Schwarzschild-De Sitter (SDS) spacetime. We systematically
extend different procedures (like the expectation value of stress tensor,
response of particle detectors, periodicity in the Euclidean time etc.) for
identifying a temperature in the case of spacetimes with single horizon to the
SDS spacetime. This analysis is facilitated by using a global coordinate chart
which covers the entire SDS manifold. We find that all the procedures lead to a
consistent picture characterized by the following features: (a) In general, SDS
spacetime behaves like a non-equilibrium system characterized by two
temperatures. (b) It is not possible to associate a global temperature with SDS
spacetime except when the ratio of the two surface gravities is rational (c)
Even when the ratio of the two surface gravities is rational, the thermal
nature depends on the coordinate chart used. There exists a global coordinate
chart in which there is global equilibrium temperature while there exist other
charts in which SDS behaves as though it has two different temperatures. The
coordinate dependence of the thermal nature is reminiscent of the flat
spacetime in Minkowski and Rindler coordinate charts. The implications are
discussed.
| [
{
"created": "Wed, 21 Apr 2004 14:36:31 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Choudhury",
"T. Roy",
""
],
[
"Padmanabhan",
"T.",
""
]
] | In case of spacetimes with single horizon, there exist several well-established procedures for relating the surface gravity of the horizon to a thermodynamic temperature. Such procedures, however, cannot be extended in a straightforward manner when a spacetime has multiple horizons. In particular, it is not clear whether there exists a notion of global temperature characterizing the multi-horizon spacetimes. We examine the conditions under which a global temperature can exist for a spacetime with two horizons using the example of Schwarzschild-De Sitter (SDS) spacetime. We systematically extend different procedures (like the expectation value of stress tensor, response of particle detectors, periodicity in the Euclidean time etc.) for identifying a temperature in the case of spacetimes with single horizon to the SDS spacetime. This analysis is facilitated by using a global coordinate chart which covers the entire SDS manifold. We find that all the procedures lead to a consistent picture characterized by the following features: (a) In general, SDS spacetime behaves like a non-equilibrium system characterized by two temperatures. (b) It is not possible to associate a global temperature with SDS spacetime except when the ratio of the two surface gravities is rational (c) Even when the ratio of the two surface gravities is rational, the thermal nature depends on the coordinate chart used. There exists a global coordinate chart in which there is global equilibrium temperature while there exist other charts in which SDS behaves as though it has two different temperatures. The coordinate dependence of the thermal nature is reminiscent of the flat spacetime in Minkowski and Rindler coordinate charts. The implications are discussed. |
gr-qc/9911028 | Mauricio Bellini | Mauricio Bellini (Departamento de Fisica - Universidad Nacional de Mar
del Plata) | Gauge - invariant fluctuations of the metric in stochastic inflation | 4 pages, no figures, version accepted for publication in Physical
Review D (as Brief Report) | null | 10.1103/PhysRevD.61.107301 | null | gr-qc | null | I derive the stochastic equation for the perturbations of the metric for a
gauge - invariant energy - momemtum - tensor (EMT) in stochastic inflation. A
quantization for the field that describes the gauge - invariant perturbations
for the metric is developed. In a power - law expansion for the universe the
amplitude for these perturbations on a background metric could be very
important in the infrared sector.
| [
{
"created": "Mon, 8 Nov 1999 21:57:53 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Jan 2000 21:54:34 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Bellini",
"Mauricio",
"",
"Departamento de Fisica - Universidad Nacional de Mar\n del Plata"
]
] | I derive the stochastic equation for the perturbations of the metric for a gauge - invariant energy - momemtum - tensor (EMT) in stochastic inflation. A quantization for the field that describes the gauge - invariant perturbations for the metric is developed. In a power - law expansion for the universe the amplitude for these perturbations on a background metric could be very important in the infrared sector. |
gr-qc/0401014 | Jose Luis Rosales | J.L. Rosales | The Pioneer's Anomalous Doppler Drift as a Berry Phase | 7 pages, The references are now correct | null | null | null | gr-qc | null | The detected anomalous frequency drift acceleration in Pioneer's radar data
finds its explanation in a Berry phase that obtains the quantum state of a
photon that propagates within an expanding space-time. The clock acceleration
is just the adiabatic expansion rate and an analogy between the effect and
Foucault's experiment is fully suggested. In this sense, light rays play a
similar role in the expanding space than Foucault's Pendulum does while
determining Earth's rotation. On the other hand, one could speculate about a
suitable future experiment at "laboratory" scales able to measure the local
cosmological expansion rate using the procedure outlined in this paper.
| [
{
"created": "Mon, 5 Jan 2004 11:16:28 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Jan 2004 08:07:37 GMT",
"version": "v2"
},
{
"created": "Mon, 10 May 2004 09:32:15 GMT",
"version": "v3"
},
{
"created": "Thu, 13 May 2004 09:32:16 GMT",
"version": "v4"
}
] | 2007-05-23 | [
[
"Rosales",
"J. L.",
""
]
] | The detected anomalous frequency drift acceleration in Pioneer's radar data finds its explanation in a Berry phase that obtains the quantum state of a photon that propagates within an expanding space-time. The clock acceleration is just the adiabatic expansion rate and an analogy between the effect and Foucault's experiment is fully suggested. In this sense, light rays play a similar role in the expanding space than Foucault's Pendulum does while determining Earth's rotation. On the other hand, one could speculate about a suitable future experiment at "laboratory" scales able to measure the local cosmological expansion rate using the procedure outlined in this paper. |
2010.11201 | Sarunas Verner | Sarunas Verner | Quintessential Inflation in Palatini Gravity | 27 pages, 2 figures, 2 tables; v2: minor revision, references added,
matches the published version | null | 10.1088/1475-7516/2021/04/001 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study a model of quintessential inflation in the context of Palatini
gravity. As a representative example, we consider the Peebles-Vilenkin model of
quintessential inflation with a small non-minimal coupling to gravity, which is
consistent with the most recent Planck measurements. At the end of inflation,
the inflaton field passes through a tachyonic region and it leads to explosive
particle production through the tachyonic preheating process. After preheating,
the Universe becomes dominated by the kinetic energy of the inflaton and enters
a period of kination. Eventually, the total energy density of the Universe
becomes dominated by radiation, resulting in reheating. We find that the model
predicts the reheating temperature values $T_{\rm{RH}} \sim \mathcal{O}(10^3 -
10^8) \, \rm{GeV}$, which is significantly above the temperature of Big Bang
Nucleosynthesis. Following reheating, the inflaton field rolls down the
quintessence potential until it freezes. Since the quintessence remains frozen
until the present day, the residual potential energy density at this field
value explains the observed dark energy density.
| [
{
"created": "Wed, 21 Oct 2020 18:00:03 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Apr 2021 17:56:33 GMT",
"version": "v2"
}
] | 2021-07-19 | [
[
"Verner",
"Sarunas",
""
]
] | We study a model of quintessential inflation in the context of Palatini gravity. As a representative example, we consider the Peebles-Vilenkin model of quintessential inflation with a small non-minimal coupling to gravity, which is consistent with the most recent Planck measurements. At the end of inflation, the inflaton field passes through a tachyonic region and it leads to explosive particle production through the tachyonic preheating process. After preheating, the Universe becomes dominated by the kinetic energy of the inflaton and enters a period of kination. Eventually, the total energy density of the Universe becomes dominated by radiation, resulting in reheating. We find that the model predicts the reheating temperature values $T_{\rm{RH}} \sim \mathcal{O}(10^3 - 10^8) \, \rm{GeV}$, which is significantly above the temperature of Big Bang Nucleosynthesis. Following reheating, the inflaton field rolls down the quintessence potential until it freezes. Since the quintessence remains frozen until the present day, the residual potential energy density at this field value explains the observed dark energy density. |
1909.04347 | Kai Lin | Kai Lin, Yunqi Liu, Wei-Liang Qian, Bin Wang and Elcio Abdalla | On quasinormal modes for the Vaidya metric in asymptotically anti-de
Sitter spacetime | Accepted for publication in Physical Review D | Phys. Rev. D 100, 065018 (2019) | 10.1103/PhysRevD.100.065018 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we present a numerical scheme to study the quasinormal modes of
the time-dependent Vaidya black hole metric in asymptotically anti-de Sitter
spacetime. The proposed algorithm is primarily based on a generalized matrix
method for quasinormal modes. The main feature of the present approach is that
the quasinormal frequency, as a function of time, is obtained by a generalized
secular equation and therefore a satisfactory degree of precision is achieved.
The implications of the results are discussed.
| [
{
"created": "Tue, 10 Sep 2019 08:18:33 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Sep 2019 04:05:47 GMT",
"version": "v2"
}
] | 2019-10-02 | [
[
"Lin",
"Kai",
""
],
[
"Liu",
"Yunqi",
""
],
[
"Qian",
"Wei-Liang",
""
],
[
"Wang",
"Bin",
""
],
[
"Abdalla",
"Elcio",
""
]
] | In this work, we present a numerical scheme to study the quasinormal modes of the time-dependent Vaidya black hole metric in asymptotically anti-de Sitter spacetime. The proposed algorithm is primarily based on a generalized matrix method for quasinormal modes. The main feature of the present approach is that the quasinormal frequency, as a function of time, is obtained by a generalized secular equation and therefore a satisfactory degree of precision is achieved. The implications of the results are discussed. |
1811.04904 | Alex Nielsen | Alex B. Nielsen, Collin D. Capano, Ofek Birnholtz, Julian Westerweck | Parameter estimation for black hole echo signals and their statistical
significance | 7 pages, 5 figures. Typo fixes and references added in v2 | Phys. Rev. D 99, 104012 (2019) | 10.1103/PhysRevD.99.104012 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Searching for black hole echo signals with gravitational waves provides a
means of probing the near-horizon regime of these objects. We demonstrate a
pipeline to efficiently search for these signals in gravitational wave data and
calculate model selection probabilities between signal and no-signal
hypotheses. As an example of its use we calculate Bayes factors for the
Abedi-Dykaar-Afshordi (ADA) model on events in LIGO's first observing run and
compare to existing results in the literature. We discuss the benefits of using
a full likelihood exploration over existing search methods that used template
banks and calculated p-values. We use the waveforms of ADA, although the method
is easily extendable to other waveforms. With these waveforms we are able to
demonstrate a range of echo amplitudes that is already is ruled out by the
data.
| [
{
"created": "Mon, 12 Nov 2018 18:44:05 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Nov 2018 18:40:36 GMT",
"version": "v2"
}
] | 2019-05-15 | [
[
"Nielsen",
"Alex B.",
""
],
[
"Capano",
"Collin D.",
""
],
[
"Birnholtz",
"Ofek",
""
],
[
"Westerweck",
"Julian",
""
]
] | Searching for black hole echo signals with gravitational waves provides a means of probing the near-horizon regime of these objects. We demonstrate a pipeline to efficiently search for these signals in gravitational wave data and calculate model selection probabilities between signal and no-signal hypotheses. As an example of its use we calculate Bayes factors for the Abedi-Dykaar-Afshordi (ADA) model on events in LIGO's first observing run and compare to existing results in the literature. We discuss the benefits of using a full likelihood exploration over existing search methods that used template banks and calculated p-values. We use the waveforms of ADA, although the method is easily extendable to other waveforms. With these waveforms we are able to demonstrate a range of echo amplitudes that is already is ruled out by the data. |
2309.06498 | Benjamin Wade | David A. Nichols, Benjamin A. Wade, Alexander M. Grant | Secondary accretion of dark matter in intermediate mass-ratio inspirals:
Dark-matter dynamics and gravitational-wave phase | 24 pages, 6 figures; v2: fixed typos, matches version published in
PRD | Phys. Rev. D 108, 124062 (2023) | 10.1103/PhysRevD.108.124062 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | When particle dark matter is bound gravitationally around a massive black
hole in sufficiently high densities, the dark matter will affect the rate of
inspiral of a secondary compact object that forms a binary with the massive
black hole. In this paper, we revisit previous estimates of the impact of
dark-matter accretion by black-hole secondaries on the emitted gravitational
waves. We identify a region of parameter space of binaries for which estimates
of the accretion were too large (specifically, because the dark-matter
distribution was assumed to be unchanging throughout the process, and the
secondary black hole accreted more mass in dark matter than that enclosed
within the orbit of the secondary). To restore consistency in these scenarios,
we propose and implement a method to remove dark-matter particles from the
distribution function when they are accreted by the secondary. This new
feedback procedure then satisfies mass conservation, and when evolved with
physically reasonable initial data, the mass accreted by the secondary no
longer exceeds the mass enclosed within its orbital radius. Comparing the
simulations with accretion feedback to those without this feedback, including
feedback leads to a smaller gravitational-wave dephasing from binaries in which
only the effects of dynamical friction are being modeled. Nevertheless, the
dephasing can be hundreds to almost a thousand gravitational-wave cycles, an
amount that should allow the effects of accretion to be inferred from
gravitational-wave measurements of these systems.
| [
{
"created": "Tue, 12 Sep 2023 18:11:21 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Jan 2024 21:40:05 GMT",
"version": "v2"
}
] | 2024-01-09 | [
[
"Nichols",
"David A.",
""
],
[
"Wade",
"Benjamin A.",
""
],
[
"Grant",
"Alexander M.",
""
]
] | When particle dark matter is bound gravitationally around a massive black hole in sufficiently high densities, the dark matter will affect the rate of inspiral of a secondary compact object that forms a binary with the massive black hole. In this paper, we revisit previous estimates of the impact of dark-matter accretion by black-hole secondaries on the emitted gravitational waves. We identify a region of parameter space of binaries for which estimates of the accretion were too large (specifically, because the dark-matter distribution was assumed to be unchanging throughout the process, and the secondary black hole accreted more mass in dark matter than that enclosed within the orbit of the secondary). To restore consistency in these scenarios, we propose and implement a method to remove dark-matter particles from the distribution function when they are accreted by the secondary. This new feedback procedure then satisfies mass conservation, and when evolved with physically reasonable initial data, the mass accreted by the secondary no longer exceeds the mass enclosed within its orbital radius. Comparing the simulations with accretion feedback to those without this feedback, including feedback leads to a smaller gravitational-wave dephasing from binaries in which only the effects of dynamical friction are being modeled. Nevertheless, the dephasing can be hundreds to almost a thousand gravitational-wave cycles, an amount that should allow the effects of accretion to be inferred from gravitational-wave measurements of these systems. |
1303.0215 | Jiri Podolsky | Jiri Podolsky, Robert Svarc | Explicit algebraic classification of Kundt geometries in any dimension | 26 pages, no figures. Presentation improved. To appear in Classical
and Quantum Gravity | Class.Quant.Grav.30:125007,2013 | 10.1088/0264-9381/30/12/125007 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an algebraic classification, based on the null alignment
properties of the Weyl tensor, of the general Kundt class of spacetimes in
arbitrary dimension for which the non-expanding, non-twisting, shear-free null
direction \boldk is a (multiple) Weyl aligned null direction (WAND). No field
equations are used, so that the results apply not only to Einstein's gravity
and its direct extension to higher dimensions, but also to any metric theory of
gravity which admits the Kundt spacetimes. By an explicit evaluation of the
Weyl tensor in a natural null frame we demonstrate that all Kundt geometries
are of type I(b) or more special, and we derive simple necessary and sufficient
conditions under which \boldk becomes a double, triple or quadruple WAND. All
possible algebraically special types, including the refinement to subtypes, are
identified, namely II(a), II(b), II(c), II(d), III(a), III(b), N, O, II_i,
III_i, D(a), D(b), D(c) and D(d). The corresponding conditions are surprisingly
clear and expressed in an invariant geometric form. Some of them are always
satisfied in four dimensions. To illustrate our classification scheme, we apply
it to the most important subfamilies of the Kundt class, namely the pp-waves,
the VSI spacetimes, and generalization of the Bertotti-Robinson, Nariai, and
Plebanski-Hacyan direct-product spacetimes of any dimension.
| [
{
"created": "Fri, 1 Mar 2013 16:38:16 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Apr 2013 14:17:24 GMT",
"version": "v2"
},
{
"created": "Tue, 18 Jun 2013 15:27:30 GMT",
"version": "v3"
}
] | 2013-06-19 | [
[
"Podolsky",
"Jiri",
""
],
[
"Svarc",
"Robert",
""
]
] | We present an algebraic classification, based on the null alignment properties of the Weyl tensor, of the general Kundt class of spacetimes in arbitrary dimension for which the non-expanding, non-twisting, shear-free null direction \boldk is a (multiple) Weyl aligned null direction (WAND). No field equations are used, so that the results apply not only to Einstein's gravity and its direct extension to higher dimensions, but also to any metric theory of gravity which admits the Kundt spacetimes. By an explicit evaluation of the Weyl tensor in a natural null frame we demonstrate that all Kundt geometries are of type I(b) or more special, and we derive simple necessary and sufficient conditions under which \boldk becomes a double, triple or quadruple WAND. All possible algebraically special types, including the refinement to subtypes, are identified, namely II(a), II(b), II(c), II(d), III(a), III(b), N, O, II_i, III_i, D(a), D(b), D(c) and D(d). The corresponding conditions are surprisingly clear and expressed in an invariant geometric form. Some of them are always satisfied in four dimensions. To illustrate our classification scheme, we apply it to the most important subfamilies of the Kundt class, namely the pp-waves, the VSI spacetimes, and generalization of the Bertotti-Robinson, Nariai, and Plebanski-Hacyan direct-product spacetimes of any dimension. |
gr-qc/0405049 | Rituparno Goswami | Rituparno Goswami, Pankaj S Joshi | Cosmic Censorship in Higher Dimensions | 4 Pages, Revtex4, 1 figure | Phys.Rev. D69 (2004) 104002 | 10.1103/PhysRevD.69.104002 | null | gr-qc hep-th | null | We show that the naked singularities arising in dust collapse from smooth
initial data (which include those discovered by Eardley and Smarr,
Christodoulou, and Newman) are removed when we make transition to higher
dimensional spacetimes. The cosmic censorship is then restored for dust
collapse which will always produce a black hole as the collapse end state for
dimensions $D\ge6$, under conditions to be motivated physically such as the
smoothness of initial data from which the collapse develops.
| [
{
"created": "Mon, 10 May 2004 13:24:50 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Goswami",
"Rituparno",
""
],
[
"Joshi",
"Pankaj S",
""
]
] | We show that the naked singularities arising in dust collapse from smooth initial data (which include those discovered by Eardley and Smarr, Christodoulou, and Newman) are removed when we make transition to higher dimensional spacetimes. The cosmic censorship is then restored for dust collapse which will always produce a black hole as the collapse end state for dimensions $D\ge6$, under conditions to be motivated physically such as the smoothness of initial data from which the collapse develops. |
gr-qc/0511081 | Andrew Beckwith | A.W.Beckwith | How soliton-anti soliton di quark pairs signify an Einstein constant
dominated cosmology, and lead to new inflationary cosmology physics | 45 pages, 3 figures, very expanded version of material in accepted
PANIC 2005 talk at Santa Fe, NM, which will in abbreviated form be in AIP
published proceedings for PANIC 2005 | Electron.J.Theor.Phys. 9 (2006) 7-33 | null | null | gr-qc | null | We review the results of a model of how nucleation of a new universe occurs,
assuming a di quark identification for soliton-anti soliton constituent parts
of a scalar field. Initially, we employ a false vacuum potential system;
however ,when cosmological expansion is dominated by the Einstein cosmological
constant at the end of chaotic inflation, the initial di quark scalar field is
not consistent with respect to a semi classical consistency conditions we
analyze as the potential changes to the chaotic inflationary potential utilized
by Guth. We use Scherrer's derivation of a sound speed being zero during
initial inflationary cosmology, and obtain a sound speed approaching unity as
the slope of the scalar field moves away from a thin wall approximation. All
this is to aid in a data reconstruction problem of how to account for the
initial origins of CMB due to dark matter since effective field theories as
presently constructed require a cut off value for applicability of their
potential structure. This is often at the cost of, especially in early universe
theoretical models, of clearly defined baryogenesis, and of a well defined
mechanism of phase transitions.
| [
{
"created": "Tue, 15 Nov 2005 19:39:18 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Beckwith",
"A. W.",
""
]
] | We review the results of a model of how nucleation of a new universe occurs, assuming a di quark identification for soliton-anti soliton constituent parts of a scalar field. Initially, we employ a false vacuum potential system; however ,when cosmological expansion is dominated by the Einstein cosmological constant at the end of chaotic inflation, the initial di quark scalar field is not consistent with respect to a semi classical consistency conditions we analyze as the potential changes to the chaotic inflationary potential utilized by Guth. We use Scherrer's derivation of a sound speed being zero during initial inflationary cosmology, and obtain a sound speed approaching unity as the slope of the scalar field moves away from a thin wall approximation. All this is to aid in a data reconstruction problem of how to account for the initial origins of CMB due to dark matter since effective field theories as presently constructed require a cut off value for applicability of their potential structure. This is often at the cost of, especially in early universe theoretical models, of clearly defined baryogenesis, and of a well defined mechanism of phase transitions. |
gr-qc/0609060 | Sean Robinson | Sean P. Robinson | Normalization conventions for Newton's constant and the Planck scale in
arbitrary spacetime dimension | 4 pages, 2 figures, RevTeX4 | null | null | null | gr-qc | null | We calculate, in d spacetime dimensions, the relationship between the
coefficient 1/K^2 of the Einstein-Hilbert term in the action of general
relativity and the coefficient G_N of the force law that results from the
Newtonian limit of general relativity. The result is
K^2=2[(d-2)/(d-3)]Vol(S^[d-2])G_N, where Vol(S^n) is the volume of the unit
n-sphere. While the d=4 case is an elementary calculation in any general
relativity text, the arbitrary case presented here is slightly less well known.
We discuss the relevance of this result for the definition of the so-called
"reduced Planck mass" and comment very briefly on the implications for brane
world models. [abstract abridged]
| [
{
"created": "Sun, 17 Sep 2006 01:09:57 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Robinson",
"Sean P.",
""
]
] | We calculate, in d spacetime dimensions, the relationship between the coefficient 1/K^2 of the Einstein-Hilbert term in the action of general relativity and the coefficient G_N of the force law that results from the Newtonian limit of general relativity. The result is K^2=2[(d-2)/(d-3)]Vol(S^[d-2])G_N, where Vol(S^n) is the volume of the unit n-sphere. While the d=4 case is an elementary calculation in any general relativity text, the arbitrary case presented here is slightly less well known. We discuss the relevance of this result for the definition of the so-called "reduced Planck mass" and comment very briefly on the implications for brane world models. [abstract abridged] |
2212.01723 | Yan-Gang Miao | Yang Guo, Yan-Gang Miao | On heat properties of charged AdS black holes in Gauss-Bonnet gravity
coupled with nonlinear electrodynamics | v1: 11 pages, 5 figures; v2: 19 pages, 6 figures, clarifications and
references added, final version to appear in Physics Letters B | Phys. Lett. B 840 (2023) 137884 (12 pages) | 10.1016/j.physletb.2023.137884 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the heat properties of charged AdS black holes in the
Gauss-Bonnet gravity coupled with nonlinear electrodynamics. We consider the
thermodynamics of black holes from the perspective of heat capacity and show
that the nonlinear electrodynamics can be helpful to improve the thermodynamic
stability of black holes. We perform a two-dimensional description in order to
reproduce the Hawking temperature, which confirms that the Hawking temperature
has an intrinsic topological nature and holds for a higher dimensional
spherically symmetric spacetime. We also analyze the Maxwell equal area law and
coexistence curve, and find the existence of van der Waals-like phase
transitions based on critical exponents. Moreover, we deal with a charged AdS
black hole in the Gauss-Bonnet gravity coupled with nonlinear electrodynamics
as a working material to study holographic heat engines and obtain an exact
expression for the efficiency of a rectangular engine cycle. We then discuss
the effects of nonlinear electrodynamics and Gauss-Bonnet couplings on the
rectangular engine cycle and compare the efficiency of this cycle with that of
the Carnot cycle.
| [
{
"created": "Sun, 4 Dec 2022 02:19:22 GMT",
"version": "v1"
},
{
"created": "Sat, 8 Apr 2023 10:35:31 GMT",
"version": "v2"
}
] | 2023-04-11 | [
[
"Guo",
"Yang",
""
],
[
"Miao",
"Yan-Gang",
""
]
] | We investigate the heat properties of charged AdS black holes in the Gauss-Bonnet gravity coupled with nonlinear electrodynamics. We consider the thermodynamics of black holes from the perspective of heat capacity and show that the nonlinear electrodynamics can be helpful to improve the thermodynamic stability of black holes. We perform a two-dimensional description in order to reproduce the Hawking temperature, which confirms that the Hawking temperature has an intrinsic topological nature and holds for a higher dimensional spherically symmetric spacetime. We also analyze the Maxwell equal area law and coexistence curve, and find the existence of van der Waals-like phase transitions based on critical exponents. Moreover, we deal with a charged AdS black hole in the Gauss-Bonnet gravity coupled with nonlinear electrodynamics as a working material to study holographic heat engines and obtain an exact expression for the efficiency of a rectangular engine cycle. We then discuss the effects of nonlinear electrodynamics and Gauss-Bonnet couplings on the rectangular engine cycle and compare the efficiency of this cycle with that of the Carnot cycle. |
1911.00967 | Sven Hirsch | Hubert Bray, Benjamin Hamm, Sven Hirsch, James Wheeler and Yiyue Zhang | Flatly Foliated Relativity | 29 pages, 2 figures | null | null | null | gr-qc math.AP math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Flatly Foliated Relativity (FFR) is a new theory which conceptually lies
between Special Relativity (SR) and General Relativity (GR), in which spacetime
is foliated by flat Euclidean spaces. While GR is based on the idea that
"matter curves spacetime", FFR is based on the idea that "matter curves
spacetime, but not space". This idea, inspired by the observed spatial flatness
of our local universe, is realized by considering the same action as used in
GR, but restricting it only to metrics which are foliated by flat spatial
slices. FFR can be thought of as describing gravity without gravitational
waves.
In FFR, a positive cosmological constant implies several interesting
properties which do not follow in GR: the metric equations are elliptic on each
euclidean slice, there exists a unique vacuum solution among those spherically
symmetric at infinity, and there exists a geometric way to define the arrow of
time. Furthermore, as gravitational waves do not exist in FFR, there are simple
analogs to the positive mass theorem and Penrose-type inequalities.
Importantly, given that gravitational waves have a negligible effect on the
curvature of spacetime, and that the universe appears to be locally flat, FFR
may be a good approximation of GR. Moreover, FFR still admits many notable
features of GR including the big bang, an accelerating expansion of the
universe, and the Schwarzschild spacetime. Lastly, FFR is already known to have
an existence theory for some simplified cases, which provokes an interesting
discussion regarding the possibility of a more general existence theory, which
may be relevant to understanding existence of solutions to GR.
| [
{
"created": "Sun, 3 Nov 2019 21:09:37 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Nov 2019 03:18:10 GMT",
"version": "v2"
}
] | 2019-11-15 | [
[
"Bray",
"Hubert",
""
],
[
"Hamm",
"Benjamin",
""
],
[
"Hirsch",
"Sven",
""
],
[
"Wheeler",
"James",
""
],
[
"Zhang",
"Yiyue",
""
]
] | Flatly Foliated Relativity (FFR) is a new theory which conceptually lies between Special Relativity (SR) and General Relativity (GR), in which spacetime is foliated by flat Euclidean spaces. While GR is based on the idea that "matter curves spacetime", FFR is based on the idea that "matter curves spacetime, but not space". This idea, inspired by the observed spatial flatness of our local universe, is realized by considering the same action as used in GR, but restricting it only to metrics which are foliated by flat spatial slices. FFR can be thought of as describing gravity without gravitational waves. In FFR, a positive cosmological constant implies several interesting properties which do not follow in GR: the metric equations are elliptic on each euclidean slice, there exists a unique vacuum solution among those spherically symmetric at infinity, and there exists a geometric way to define the arrow of time. Furthermore, as gravitational waves do not exist in FFR, there are simple analogs to the positive mass theorem and Penrose-type inequalities. Importantly, given that gravitational waves have a negligible effect on the curvature of spacetime, and that the universe appears to be locally flat, FFR may be a good approximation of GR. Moreover, FFR still admits many notable features of GR including the big bang, an accelerating expansion of the universe, and the Schwarzschild spacetime. Lastly, FFR is already known to have an existence theory for some simplified cases, which provokes an interesting discussion regarding the possibility of a more general existence theory, which may be relevant to understanding existence of solutions to GR. |
gr-qc/0504082 | Masaru Shibata | Masaru Shibata | Constraining nuclear equations of state using gravitational waves from
hypermassive neutron stars | 4 pages, to appear in Phys. Rev. Lett | Phys.Rev.Lett. 94 (2005) 201101 | 10.1103/PhysRevLett.94.201101 | null | gr-qc astro-ph | null | Latest general relativistic simulations for merger of binary neutron stars
with realistic equations of state (EOSs) show that a hypermassive neutron star
of an ellipsoidal figure is formed after the merger if the total mass is
smaller than a threshold value which depends on the EOSs. The effective
amplitude of quasiperiodic gravitational waves from such hypermassive neutron
stars is $\sim 6$--$7 \times 10^{-21}$ at a distance of 50 Mpc, which may be
large enough for detection by advanced laser interferometric gravitational wave
detectors although the frequency is high $\sim 3$ kHz. We point out that the
detection of such signal may lead to constraining the EOSs for neutron stars.
| [
{
"created": "Tue, 19 Apr 2005 08:18:57 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Shibata",
"Masaru",
""
]
] | Latest general relativistic simulations for merger of binary neutron stars with realistic equations of state (EOSs) show that a hypermassive neutron star of an ellipsoidal figure is formed after the merger if the total mass is smaller than a threshold value which depends on the EOSs. The effective amplitude of quasiperiodic gravitational waves from such hypermassive neutron stars is $\sim 6$--$7 \times 10^{-21}$ at a distance of 50 Mpc, which may be large enough for detection by advanced laser interferometric gravitational wave detectors although the frequency is high $\sim 3$ kHz. We point out that the detection of such signal may lead to constraining the EOSs for neutron stars. |
1908.10688 | Pardyumn Kumar Sahoo | P.K. Sahoo, S. Bhattacharjee | Revisiting The Coincidence Problem in $f(R)$ Gravitation | 7 pages, 1 Figures, Published version | New Astronomy, 77 (2020), 101351 | 10.1016/j.newast.2019.101351 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The energy densities of dark matter (DM) and dark energy (DE) are of the same
order at the present epoch despite the fact that both these quantities have
contrasting characteristics and are presumed to have evolved distinctively with
cosmic evolution. This is a major issue in standard $\Lambda$CDM cosmology and
is termed "The Coincidence Problem" which hitherto cannot be explained by any
fundamental theory. In this spirit, Bisabr \cite{bisabr} reported a
cosmological scenario in $f(R)$ gravity where DM and DE interact and exchange
energy with each other and therefore evolve dependently. We investigate the
efficiency and model independancy of the technique reported in Bisabr
\cite{bisabr} in addressing the Coincidence problem with the help of two $f(R)$
gravity models with model parameters constrained from various observations. Our
result confirm the idea that not all scalar-tensor gravity theories and models
can circumvent the Coincidence Problem and any cosmological scenario with
interacting fluids is highly model dependent and hence alternate model
independent theories and ideas should be nominated to solve this mystery.
| [
{
"created": "Mon, 26 Aug 2019 11:09:24 GMT",
"version": "v1"
},
{
"created": "Sun, 22 Sep 2019 10:25:52 GMT",
"version": "v2"
},
{
"created": "Sat, 28 Dec 2019 14:11:56 GMT",
"version": "v3"
}
] | 2020-01-01 | [
[
"Sahoo",
"P. K.",
""
],
[
"Bhattacharjee",
"S.",
""
]
] | The energy densities of dark matter (DM) and dark energy (DE) are of the same order at the present epoch despite the fact that both these quantities have contrasting characteristics and are presumed to have evolved distinctively with cosmic evolution. This is a major issue in standard $\Lambda$CDM cosmology and is termed "The Coincidence Problem" which hitherto cannot be explained by any fundamental theory. In this spirit, Bisabr \cite{bisabr} reported a cosmological scenario in $f(R)$ gravity where DM and DE interact and exchange energy with each other and therefore evolve dependently. We investigate the efficiency and model independancy of the technique reported in Bisabr \cite{bisabr} in addressing the Coincidence problem with the help of two $f(R)$ gravity models with model parameters constrained from various observations. Our result confirm the idea that not all scalar-tensor gravity theories and models can circumvent the Coincidence Problem and any cosmological scenario with interacting fluids is highly model dependent and hence alternate model independent theories and ideas should be nominated to solve this mystery. |
1606.05263 | Abraao Capistrano | Abra\~ao J. S. Capistrano, Joice A. M. Penagos, Manuel S. Al\'arcon | Anomalous precession of planets on a Weyl conformastatic solution | 6 pages, revised version, Accepted for publication in MNRAS | Royal Astronomical Society. Monthly Notices, v. 463, p. 1587-1591,
2016 | 10.1093/mnras/stw1958 | null | gr-qc astro-ph.EP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate the anomalous planets precession in the
nearly-newtonian gravitational regime. This limit is obtained from the
application of the slow motion condition to the geodesic equations without
altering the geodesic deviation equations. Using a non-standard expression for
the perihelion advance from the Weyl conformastatic vacuum solution as a model,
we can describe the anomaly in planets precession compared with different
observational data from Ephemerides of the Planets and the Moon (EPM2008 and
EPM2011) and Planetary and Lunar Ephemeris (INPOP10a). As a result, using the
Levenberg-Marquardt algorithm and calculating the related Chi-squared
statistic, we find that the anomaly is statistical irrelevant in accordance
with INPOP10a observations. As a complement to this work, we also do an
application to the relativistic precession of giant planets using observational
data calibrated with the EPM2011.
| [
{
"created": "Wed, 15 Jun 2016 01:14:16 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Aug 2016 17:07:09 GMT",
"version": "v2"
}
] | 2017-04-06 | [
[
"Capistrano",
"Abraão J. S.",
""
],
[
"Penagos",
"Joice A. M.",
""
],
[
"Alárcon",
"Manuel S.",
""
]
] | In this paper, we investigate the anomalous planets precession in the nearly-newtonian gravitational regime. This limit is obtained from the application of the slow motion condition to the geodesic equations without altering the geodesic deviation equations. Using a non-standard expression for the perihelion advance from the Weyl conformastatic vacuum solution as a model, we can describe the anomaly in planets precession compared with different observational data from Ephemerides of the Planets and the Moon (EPM2008 and EPM2011) and Planetary and Lunar Ephemeris (INPOP10a). As a result, using the Levenberg-Marquardt algorithm and calculating the related Chi-squared statistic, we find that the anomaly is statistical irrelevant in accordance with INPOP10a observations. As a complement to this work, we also do an application to the relativistic precession of giant planets using observational data calibrated with the EPM2011. |
0904.2669 | Carlos A. R. Herdeiro | P.P. Avelino, A.J.S. Hamilton, C.A.R. Herdeiro | Mass Inflation in Brans-Dicke gravity | 14 pages, 15 figures | Phys.Rev.D79:124045,2009 | 10.1103/PhysRevD.79.124045 | null | gr-qc astro-ph.CO astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A detailed non-linear analysis of the internal structure of spherical,
charged black holes that are accreting scalar matter is performed in the
framework of the Brans-Dicke theory of gravity. We choose the lowest value of
the Brans-Dicke parameter that is compatible with observational constraints.
First, the homogeneous approximation is used. It indicates that mass inflation
occurs and that the variations of the Brans-Dicke scalar inside the black hole,
which could in principle be large in the absence of mass inflation, become
small when mass inflation does occur. Then, a full non-linear numerical study
of the black hole interior perturbed by a self-gravitating massless uncharged
scalar-field is performed. We use an algorithm with adaptive mesh refinement
capabilities. In this way, the changes in the internal structure of the black
hole caused by mass inflation are determined, as well as the induced variations
of the Brans-Dicke scalar, confirming, qualitatively, the indications given by
the homogeneous approximation.
| [
{
"created": "Fri, 17 Apr 2009 10:11:46 GMT",
"version": "v1"
}
] | 2010-05-12 | [
[
"Avelino",
"P. P.",
""
],
[
"Hamilton",
"A. J. S.",
""
],
[
"Herdeiro",
"C. A. R.",
""
]
] | A detailed non-linear analysis of the internal structure of spherical, charged black holes that are accreting scalar matter is performed in the framework of the Brans-Dicke theory of gravity. We choose the lowest value of the Brans-Dicke parameter that is compatible with observational constraints. First, the homogeneous approximation is used. It indicates that mass inflation occurs and that the variations of the Brans-Dicke scalar inside the black hole, which could in principle be large in the absence of mass inflation, become small when mass inflation does occur. Then, a full non-linear numerical study of the black hole interior perturbed by a self-gravitating massless uncharged scalar-field is performed. We use an algorithm with adaptive mesh refinement capabilities. In this way, the changes in the internal structure of the black hole caused by mass inflation are determined, as well as the induced variations of the Brans-Dicke scalar, confirming, qualitatively, the indications given by the homogeneous approximation. |
2103.17074 | Lo\"ic Marsot | Lo\"ic Marsot | Geometric studies of the interplay between spin and gravity | PhD thesis, 141 pages, 12 figures | null | null | null | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by-nc-nd/4.0/ | This PhD thesis is the conclusion of some of my works carried out at the
Centre de Physique Th\'eorique, under the supervision of Serge Lazzarini. Two
subjects are presented in the manuscript, both aiming at studying the effect of
the spin of elementary particles on otherwise known theories.
First is a study of the L\'evy-Leblond-Newton (LLN) equation, which is used
to describe the evolution of a quantum system with spin 1/2 that is coupled to
its own gravitational potential. After reviewing some symmetries of non
relativistic Quantum Mechanics, and how to geometrize them with the help of
Bargmann structures, we recall what is the L\'evy-Leblond equation. In this
chapter, the LLN equation is described in a fully covariant way on Bargmann
structures. This covariant formulation then helps to derive the dynamical
symmetries of the equation, and conserved quantities. The symmetry group of
this equation turns out to be the already known Schr\"odinger-Newton group.
The second part deals with the trajectory of particles with spin in General
Relativity. We first highlight Souriau's geometric method to derive the
Mathisson-Papapetrou-Dixon (MPD) equations, and then discuss the different
possible Spin Supplementary Conditions (SSC) that exist to close the system of
MPD equations. In this chapter, we assume the Tulczyjew SSC to describe the
trajectory of photons, leading to the Souriau-Saturnini equations. We then
present some works where we have applied these equations, in a Schwarzschild
spacetime, and in a spacetime deformed by a gravitational wave. In the first
work, we found gravitational birefringence: the trajectory deviates from the
geodesic plane, depending on the helicity of the photon and its wavelength. The
second work presented also found birefringence in gravitational interferometry
experiments, however the effect is many orders of magnitude lower than what we
can detect.
| [
{
"created": "Mon, 29 Mar 2021 21:59:24 GMT",
"version": "v1"
}
] | 2021-04-01 | [
[
"Marsot",
"Loïc",
""
]
] | This PhD thesis is the conclusion of some of my works carried out at the Centre de Physique Th\'eorique, under the supervision of Serge Lazzarini. Two subjects are presented in the manuscript, both aiming at studying the effect of the spin of elementary particles on otherwise known theories. First is a study of the L\'evy-Leblond-Newton (LLN) equation, which is used to describe the evolution of a quantum system with spin 1/2 that is coupled to its own gravitational potential. After reviewing some symmetries of non relativistic Quantum Mechanics, and how to geometrize them with the help of Bargmann structures, we recall what is the L\'evy-Leblond equation. In this chapter, the LLN equation is described in a fully covariant way on Bargmann structures. This covariant formulation then helps to derive the dynamical symmetries of the equation, and conserved quantities. The symmetry group of this equation turns out to be the already known Schr\"odinger-Newton group. The second part deals with the trajectory of particles with spin in General Relativity. We first highlight Souriau's geometric method to derive the Mathisson-Papapetrou-Dixon (MPD) equations, and then discuss the different possible Spin Supplementary Conditions (SSC) that exist to close the system of MPD equations. In this chapter, we assume the Tulczyjew SSC to describe the trajectory of photons, leading to the Souriau-Saturnini equations. We then present some works where we have applied these equations, in a Schwarzschild spacetime, and in a spacetime deformed by a gravitational wave. In the first work, we found gravitational birefringence: the trajectory deviates from the geodesic plane, depending on the helicity of the photon and its wavelength. The second work presented also found birefringence in gravitational interferometry experiments, however the effect is many orders of magnitude lower than what we can detect. |
1404.0260 | Ahmad Sheykhi | A. Sheykhi, M. H. Dehghani and R. Dehghani | Horizon Thermodynamics and Gravitational Field Equations in
Quasi-Topological Gravity | 9 pages | Gen Relat. Gravit. 46 (2014) 1679 | 10.1007/s10714-014-1679-1 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | In this paper we show that the gravitational field equations of $(n+1)$%
-dimensional topological black holes with constant horizon curvature, in cubic
and quartic quasi-topological gravity, can be recast in the form of the first
law of thermodynamics, $dE=TdS-PdV$, at the black hole horizon. This procedure
leads to extract an expression for the horizon entropy as well as the energy
(mass) in terms of the horizon radius, which coincide exactly with those
obtained in quasi-topological gravity by solving the field equations and using
the Wald's method. We also argue that this approach is powerful and can be
extended to all higher order quasi-topological gravity for extracting the
corresponding entropy and energy in terms of horizon radius.
| [
{
"created": "Mon, 31 Mar 2014 16:37:58 GMT",
"version": "v1"
}
] | 2015-06-19 | [
[
"Sheykhi",
"A.",
""
],
[
"Dehghani",
"M. H.",
""
],
[
"Dehghani",
"R.",
""
]
] | In this paper we show that the gravitational field equations of $(n+1)$% -dimensional topological black holes with constant horizon curvature, in cubic and quartic quasi-topological gravity, can be recast in the form of the first law of thermodynamics, $dE=TdS-PdV$, at the black hole horizon. This procedure leads to extract an expression for the horizon entropy as well as the energy (mass) in terms of the horizon radius, which coincide exactly with those obtained in quasi-topological gravity by solving the field equations and using the Wald's method. We also argue that this approach is powerful and can be extended to all higher order quasi-topological gravity for extracting the corresponding entropy and energy in terms of horizon radius. |
2001.05403 | Tommaso De Lorenzo | Tommaso De Lorenzo | Black Holes as a Gateway to the Quantum: Classical and Semi-Classical
Explorations | PhD Thesis - 146 pages; Lots of figures; Introductory sections are
not published elsewhere; The 5 Chapters overlap with published papers:
arXiv:1512.04566 [gr-qc], arXiv:1604.07222 [gr-qc], arXiv:1707.00479 [gr-qc],
arXiv:1807.02041 [gr-qc], arXiv:1811.03667 [gr-qc] | null | 10.13140/RG.2.2.18613.73449 | Num\'ero national de th\`ese / suffixe local: 2018AIXM0264 /
023ED352 | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | This thesis is entirely devoted to black hole physics as a natural arena to
study quantum gravity related questions. The five main Chapters present the
results already published in arXiv:1512.04566 [gr-qc], arXiv:1604.07222
[gr-qc], arXiv:1707.00479 [gr-qc], arXiv:1807.02041 [gr-qc], arXiv:1811.03667
[gr-qc]. A main introductory Section, together with the Sections introducing
each of the two parts of the manuscript compose the \emph{fil rouge} of the
thesis, and are not published elsewhere. They contain reviews (together with my
personal view) on the information paradox (Part 1) and the thermodynamics of
spacetime (Part 2).
| [
{
"created": "Wed, 15 Jan 2020 16:17:35 GMT",
"version": "v1"
}
] | 2020-01-16 | [
[
"De Lorenzo",
"Tommaso",
""
]
] | This thesis is entirely devoted to black hole physics as a natural arena to study quantum gravity related questions. The five main Chapters present the results already published in arXiv:1512.04566 [gr-qc], arXiv:1604.07222 [gr-qc], arXiv:1707.00479 [gr-qc], arXiv:1807.02041 [gr-qc], arXiv:1811.03667 [gr-qc]. A main introductory Section, together with the Sections introducing each of the two parts of the manuscript compose the \emph{fil rouge} of the thesis, and are not published elsewhere. They contain reviews (together with my personal view) on the information paradox (Part 1) and the thermodynamics of spacetime (Part 2). |
gr-qc/9510051 | Jorge Griego | Jorge Griego | Is the third coefficient of the Jones knot polynomial a quantum state of
gravity? | 22 pages | Phys.Rev.D53:6966-6978,1996 | 10.1103/PhysRevD.53.6966 | IFFC preprint 95-03 (Montevideo) | gr-qc | null | Some time ago it was conjectured that the coefficients of an expansion of the
Jones polynomial in terms of the cosmological constant could provide an
infinite string of knot invariants that are solutions of the vacuum Hamiltonian
constraint of quantum gravity in the loop representation. Here we discuss the
status of this conjecture at third order in the cosmological constant. The
calculation is performed in the extended loop representation, a generalization
of the loop representation. It is shown that the the Hamiltonian does not
annihilate the third coefficient of the Jones polynomal ($J_3$) for general
extended loops. For ordinary loops the result acquires an interesting
geometrical meaning and new possibilities appear for $J_3$ to represent a
quantum state of gravity.
| [
{
"created": "Wed, 25 Oct 1995 14:34:57 GMT",
"version": "v1"
}
] | 2011-09-09 | [
[
"Griego",
"Jorge",
""
]
] | Some time ago it was conjectured that the coefficients of an expansion of the Jones polynomial in terms of the cosmological constant could provide an infinite string of knot invariants that are solutions of the vacuum Hamiltonian constraint of quantum gravity in the loop representation. Here we discuss the status of this conjecture at third order in the cosmological constant. The calculation is performed in the extended loop representation, a generalization of the loop representation. It is shown that the the Hamiltonian does not annihilate the third coefficient of the Jones polynomal ($J_3$) for general extended loops. For ordinary loops the result acquires an interesting geometrical meaning and new possibilities appear for $J_3$ to represent a quantum state of gravity. |
gr-qc/0503117 | Gustavo Dotti | Gustavo Dotti and Reinaldo J. Gleiser | Linear stability of Einstein-Gauss-Bonnet static spacetimes. Part I:
tensor perturbations | 14 pages, 4 figures | Phys.Rev. D72 (2005) 044018 | 10.1103/PhysRevD.72.044018 | null | gr-qc hep-th | null | We study the stability under linear perturbations of a class of static
solutions of Einstein-Gauss-Bonnet gravity in $D=n+2$ dimensions with spatial
slices of the form $\Sigma_{\k}^n \times {\mathbb R}^+$, $\Sigma_{\k}^n$ an
$n-$manifold of constant curvature $\k$. Linear perturbations for this class of
space-times can be generally classified into tensor, vector and scalar types.
The analysis in this paper is restricted to tensor perturbations.
| [
{
"created": "Wed, 30 Mar 2005 11:51:35 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Jul 2005 11:50:48 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Dotti",
"Gustavo",
""
],
[
"Gleiser",
"Reinaldo J.",
""
]
] | We study the stability under linear perturbations of a class of static solutions of Einstein-Gauss-Bonnet gravity in $D=n+2$ dimensions with spatial slices of the form $\Sigma_{\k}^n \times {\mathbb R}^+$, $\Sigma_{\k}^n$ an $n-$manifold of constant curvature $\k$. Linear perturbations for this class of space-times can be generally classified into tensor, vector and scalar types. The analysis in this paper is restricted to tensor perturbations. |
1110.0065 | De-Cheng Zou | Kang Zhou, Rui-Hong Yue, Zhan-Ying Yang and De-Cheng Zou | Spontaneous Symmetry Breaking Vacuum Energy in Cosmology | 11 pages, no figure | null | 10.1088/1674-1056/21/7/079801 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In present paper the gravitational effect of spontaneous symmetry breaking
vacuum energy density is investigated by subtracting the flat space-time
contribution from the energy in the curved space-time. We found that the remain
effective energy-momentum tensor is too small to cause the acceleration of the
universe although it satisfies the characteristic of the dark energy. However
it could provide a promising explanation to the puzzle why the gravitational
effect produced by the huge symmetry breaking vacuum energy in the electroweak
theory has not been observed, since it has a sufficient small value (smaller
than the observed cosmic energy density by a factor $10^{32}$).
| [
{
"created": "Sat, 1 Oct 2011 02:32:05 GMT",
"version": "v1"
}
] | 2015-05-30 | [
[
"Zhou",
"Kang",
""
],
[
"Yue",
"Rui-Hong",
""
],
[
"Yang",
"Zhan-Ying",
""
],
[
"Zou",
"De-Cheng",
""
]
] | In present paper the gravitational effect of spontaneous symmetry breaking vacuum energy density is investigated by subtracting the flat space-time contribution from the energy in the curved space-time. We found that the remain effective energy-momentum tensor is too small to cause the acceleration of the universe although it satisfies the characteristic of the dark energy. However it could provide a promising explanation to the puzzle why the gravitational effect produced by the huge symmetry breaking vacuum energy in the electroweak theory has not been observed, since it has a sufficient small value (smaller than the observed cosmic energy density by a factor $10^{32}$). |
2108.09882 | Shiyang Hu | Shiyang Hu, Xin Wu, Enwei Liang | Construction of second-order six-dimensional Hamiltonian-conserving
scheme | 26 pages,13 figures | null | 10.3847/1538-4365/ac1ff3 | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | It is shown analytically that the energy-conserving implicit nonsymplectic
scheme of Bacchini, Ripperda, Chen and Sironi provides a first-order accuracy
to numerical solutions of a six-dimensional conservative Hamiltonian system.
Because of this, a new second-order energy-conserving implicit scheme is
proposed. Numerical simulations of Galactic model hosting a BL Lacertae object
and magnetized rotating black hole background support these analytical results.
The new method with appropriate time steps is used to explore the effects of
varying the parameters on the presence of chaos in the two physical models.
Chaos easily occurs in the Galactic model as the mass of the nucleus, the
internal perturbation parameter, and the anisotropy of the potential of the
elliptical galaxy increase. The dynamics of charged particles around the
magnetized Kerr spacetime is easily chaotic for larger energies of the
particles, smaller initial angular momenta of the particles, and stronger
magnetic fields. The chaotic properties are not necessarily weakened when the
black hole spin increases. The new method can be used for any six-dimensional
Hamiltonian problems, including globally hyperbolic spacetimes with readily
available (3+1) split coordinates.
| [
{
"created": "Mon, 23 Aug 2021 01:17:09 GMT",
"version": "v1"
}
] | 2021-12-08 | [
[
"Hu",
"Shiyang",
""
],
[
"Wu",
"Xin",
""
],
[
"Liang",
"Enwei",
""
]
] | It is shown analytically that the energy-conserving implicit nonsymplectic scheme of Bacchini, Ripperda, Chen and Sironi provides a first-order accuracy to numerical solutions of a six-dimensional conservative Hamiltonian system. Because of this, a new second-order energy-conserving implicit scheme is proposed. Numerical simulations of Galactic model hosting a BL Lacertae object and magnetized rotating black hole background support these analytical results. The new method with appropriate time steps is used to explore the effects of varying the parameters on the presence of chaos in the two physical models. Chaos easily occurs in the Galactic model as the mass of the nucleus, the internal perturbation parameter, and the anisotropy of the potential of the elliptical galaxy increase. The dynamics of charged particles around the magnetized Kerr spacetime is easily chaotic for larger energies of the particles, smaller initial angular momenta of the particles, and stronger magnetic fields. The chaotic properties are not necessarily weakened when the black hole spin increases. The new method can be used for any six-dimensional Hamiltonian problems, including globally hyperbolic spacetimes with readily available (3+1) split coordinates. |
1407.8058 | Hrvoje Nikolic | H. Nikolic | If time is a local observable, then Hawking radiation is unitary | 11 pages, accepted for publication in Int. J. Quantum Inf. arXiv
admin note: substantial text overlap with arXiv:1101.2744 | Int. J. Quant. Inf. 12, 1560001 (2014) | null | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the usual formulation of quantum theory, time is a global classical
evolution parameter, not a local quantum observable. On the other hand, both
canonical quantum gravity (which lacks fundamental time-evolution parameter)
and the principle of spacetime covariance (which insists that time should be
treated on an equal footing with space) suggest that quantum theory should be
slightly reformulated, in a manner that promotes time to a local observable.
Such a reformulated quantum theory is unitary in a more general sense than the
usual quantum theory. In particular, this promotes the non-unitary Hawking
radiation to a unitary phenomenon, which avoids the black-hole information
paradox.
| [
{
"created": "Mon, 28 Jul 2014 07:10:39 GMT",
"version": "v1"
}
] | 2015-03-17 | [
[
"Nikolic",
"H.",
""
]
] | In the usual formulation of quantum theory, time is a global classical evolution parameter, not a local quantum observable. On the other hand, both canonical quantum gravity (which lacks fundamental time-evolution parameter) and the principle of spacetime covariance (which insists that time should be treated on an equal footing with space) suggest that quantum theory should be slightly reformulated, in a manner that promotes time to a local observable. Such a reformulated quantum theory is unitary in a more general sense than the usual quantum theory. In particular, this promotes the non-unitary Hawking radiation to a unitary phenomenon, which avoids the black-hole information paradox. |
1409.0720 | Sergey Chervon | Renat R. Abbyazov, Sergey V. Chervon, Volker M\"uller | $\sigma$CDM coupled to radiation. Dark energy and Universe acceleration | 11 pages, 7 figures | null | 10.1142/S021773231550114X | NIL GCA 6/2014 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently the Chiral Cosmological Model (CCM) coupled to cold dark matter
(CDM) has been investigated as $\sigma$CDM model to study the observed
accelerated expansion of the Universe. Dark sector fields (as Dark Energy
content) coupled to cosmic dust were considered as the source of Einstein
gravity in Friedmann-Robertson-Walker (FRW) cosmology. Such model had a
beginning at the matter-dominated era. The purposes of our present
investigation are two folds: to extend <<life>> of the $\sigma$CDM for earlier
times to radiation-dominated era and to take into account variation of the
exponential potential via variation of the interaction parameter $\lambda $.
We use Markov Chain Monte Carlo (MCMC) procedure to investigate possible
values of initial conditions constrained by the measured amount of the dark
matter, dark energy and radiation component today.
Our analysis includes dark energy contribution to critical density, the ratio
of the kinetic and potential energies, deceleration parameter, effective
equation of state and evolution of DE equation of state with variation of
coupling constant $\lambda $. A comparison with the $\Lambda$CDM model was
performed. A new feature of the model is the existence of some values of
potential coupling constant, leading to a $\sigma$CDM solution without transit
into accelerated expansion epoch.
| [
{
"created": "Tue, 2 Sep 2014 14:13:56 GMT",
"version": "v1"
}
] | 2015-08-26 | [
[
"Abbyazov",
"Renat R.",
""
],
[
"Chervon",
"Sergey V.",
""
],
[
"Müller",
"Volker",
""
]
] | Recently the Chiral Cosmological Model (CCM) coupled to cold dark matter (CDM) has been investigated as $\sigma$CDM model to study the observed accelerated expansion of the Universe. Dark sector fields (as Dark Energy content) coupled to cosmic dust were considered as the source of Einstein gravity in Friedmann-Robertson-Walker (FRW) cosmology. Such model had a beginning at the matter-dominated era. The purposes of our present investigation are two folds: to extend <<life>> of the $\sigma$CDM for earlier times to radiation-dominated era and to take into account variation of the exponential potential via variation of the interaction parameter $\lambda $. We use Markov Chain Monte Carlo (MCMC) procedure to investigate possible values of initial conditions constrained by the measured amount of the dark matter, dark energy and radiation component today. Our analysis includes dark energy contribution to critical density, the ratio of the kinetic and potential energies, deceleration parameter, effective equation of state and evolution of DE equation of state with variation of coupling constant $\lambda $. A comparison with the $\Lambda$CDM model was performed. A new feature of the model is the existence of some values of potential coupling constant, leading to a $\sigma$CDM solution without transit into accelerated expansion epoch. |
gr-qc/0311046 | Edgard Casal de Rey Neto | E. C. de Rey Neto, J.C.N. de Araujo, O. D. Aguiar | Wave polarizations for a beam-like gravitational wave in quadratic
curvature gravity | 5 pages, 3 figures, minor corrections, to appear in CQG | Class.Quant.Grav. 21 (2004) S541-S544 | 10.1088/0264-9381/21/5/023 | null | gr-qc | null | We compute analytically the tidal field and polarizations of an exact
gravitational wave generated by a cylindrical beam of null matter of finite
width and length in quadratic curvature gravity. We propose that this wave can
represent the gravitational wave that keep up with the high energy photons
produced in a gamma ray burst (GRB) source.
| [
{
"created": "Fri, 14 Nov 2003 10:50:46 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Nov 2003 15:01:04 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Neto",
"E. C. de Rey",
""
],
[
"de Araujo",
"J. C. N.",
""
],
[
"Aguiar",
"O. D.",
""
]
] | We compute analytically the tidal field and polarizations of an exact gravitational wave generated by a cylindrical beam of null matter of finite width and length in quadratic curvature gravity. We propose that this wave can represent the gravitational wave that keep up with the high energy photons produced in a gamma ray burst (GRB) source. |
gr-qc/9909003 | Jerzy Kowalczynski | J.K. Kowalczynski (Institute of Physics, Polish Academy of Sciences) | A Twisting Electrovac Solution of Type II with the Cosmological Constant | 4 pages, LaTeX 2e, no figures. The present (second) version,
identical to that published in General Relativity and Gravitation, is derived
from the first version by presenting the admitted Killing vector, and by
adding the last paragraph, two footnotes (here Footnotes 1 and 3), and two
references (here Refs. [3,4]) | Gen.Rel.Grav. 32 (2000) 959-962 | 10.1023/A:1001945310297 | null | gr-qc | null | An exact solution of the current-free Einstein-Maxwell equations with the
cosmological constant is presented. It is of Petrov type II, and its double
principal null vector is geodesic, shear-free, expanding, and twisting. The
solution contains five constants. Its electromagnetic field is non-null and
aligned. The solution admits only one Killing vector and includes, as special
cases, several known solutions.
| [
{
"created": "Wed, 1 Sep 1999 14:14:27 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Nov 2000 12:20:16 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Kowalczynski",
"J. K.",
"",
"Institute of Physics, Polish Academy of Sciences"
]
] | An exact solution of the current-free Einstein-Maxwell equations with the cosmological constant is presented. It is of Petrov type II, and its double principal null vector is geodesic, shear-free, expanding, and twisting. The solution contains five constants. Its electromagnetic field is non-null and aligned. The solution admits only one Killing vector and includes, as special cases, several known solutions. |
1506.02788 | Anuradha Gupta | Anuradha Gupta and Achamveedu Gopakumar | Time-domain inspiral templates for spinning compact binaries in
quasi-circular orbits | 10 pages, 1 figure. Contribution to the proceedings of "Equations of
Motion in Relativistic Gravity", Bad Honnef, Germany, 17 Feb - 23 Feb 2013 | null | 10.1007/978-3-319-18335-0_26 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a prescription to compute the time-domain gravitational wave (GW)
polarization states associated with spinning compact binaries inspiraling along
quasi-circular orbits. We invoke the orbital angular momentum ${\bf L}$ rather
than its Newtonian counterpart ${\bf L_{\rm N}}$ to describe the orbits and the
two spin vectors are freely specified in the source frame associated with the
initial direction of the total angular momentum. We discuss the various
implications of our approach.
| [
{
"created": "Tue, 9 Jun 2015 06:09:25 GMT",
"version": "v1"
}
] | 2021-04-07 | [
[
"Gupta",
"Anuradha",
""
],
[
"Gopakumar",
"Achamveedu",
""
]
] | We present a prescription to compute the time-domain gravitational wave (GW) polarization states associated with spinning compact binaries inspiraling along quasi-circular orbits. We invoke the orbital angular momentum ${\bf L}$ rather than its Newtonian counterpart ${\bf L_{\rm N}}$ to describe the orbits and the two spin vectors are freely specified in the source frame associated with the initial direction of the total angular momentum. We discuss the various implications of our approach. |
2101.12688 | Gustav Mogull | Gustav Uhre Jakobsen, Gustav Mogull, Jan Plefka, Jan Steinhoff | Classical Gravitational Bremsstrahlung from a Worldline Quantum Field
Theory | v3: additional supplementary material; accepted for publication in
PRL | Phys. Rev. Lett. 126, 201103 (2021) | 10.1103/PhysRevLett.126.201103 | HU-EP-21/03-RTG | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the recently established formalism of a worldline quantum field theory
(WQFT) description of the classical scattering of two spinless black holes, we
compute the far-field time-domain waveform of the gravitational waves produced
in the encounter at leading order in the post-Minkowskian (weak field, but
generic velocity) expansion. We reproduce previous results of Kovacs and Thorne
in a highly economic way. Then using the waveform we extract the leading-order
total radiated angular momentum and energy (including differential results).
Our work may enable crucial improvements of gravitational-wave predictions in
the regime of large relative velocities.
| [
{
"created": "Fri, 29 Jan 2021 17:17:17 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Feb 2021 18:53:23 GMT",
"version": "v2"
},
{
"created": "Thu, 22 Apr 2021 15:48:02 GMT",
"version": "v3"
}
] | 2021-05-26 | [
[
"Jakobsen",
"Gustav Uhre",
""
],
[
"Mogull",
"Gustav",
""
],
[
"Plefka",
"Jan",
""
],
[
"Steinhoff",
"Jan",
""
]
] | Using the recently established formalism of a worldline quantum field theory (WQFT) description of the classical scattering of two spinless black holes, we compute the far-field time-domain waveform of the gravitational waves produced in the encounter at leading order in the post-Minkowskian (weak field, but generic velocity) expansion. We reproduce previous results of Kovacs and Thorne in a highly economic way. Then using the waveform we extract the leading-order total radiated angular momentum and energy (including differential results). Our work may enable crucial improvements of gravitational-wave predictions in the regime of large relative velocities. |
2404.14766 | Phongpichit Channuie | Phongpichit Channuie (Walailak U.) | Observational Constraints on Asymptotic Safety Inflation in Gravity
Rainbow | v2: 20 pages, 4 figures, more references added, added discussion and
new plots. arXiv admin note: text overlap with arXiv:1903.05996,
arXiv:2005.08310 | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Using suitable Renormalization Group (RG) based re-summation of quantum
corrections to $R^2$ term, a re-summed version of the effective Lagrangian can
be obtained \cite{Demmel:2015oqa}. In the context of gravity as an
Asymptotically Safe (AS) theory, authors of
Refs.\cite{Liu:2018hno,Koshelev:2022olc} proposed a refined Starobinsky model,
$L_{\rm AS} = M^{2}_{p} R/2+(\alpha/2)R^{2}/[1+\beta \ln(R/\mu^{2})]$, where
$R$ is the Ricci scalar, $\alpha$ and $\beta$ are constants and $\mu$ is an
energy scale. In the present work, we embed this underlying effective
Lagrangian within the framework of gravity's rainbow. By implementing the COBE
normalization and the Planck constraint on the scalar spectrum, we demonstrate
that the power spectrum of curvature perturbation relies on $\alpha$ and
$\beta$, as well as on a rainbow parameter. Similarly, the scalar spectral
index $n_s$ is influenced by $\beta$ and the rainbow parameter, yet remains
unaffected by $\alpha$. Additionally, the tensor-to-scalar ratio $r$ solely
depends on the rainbow parameter. Remarkably, when requiring $n_s$ to be
consistent with the Planck collaboration at $1\sigma$ confidence level, the
upper limit on the tensor-to-scalar ratio $r < 0.036$ can be naturally
satisfied. This value potentially holds promise for potential measurement by
Stage IV CMB ground experiments and is certainly within reach of future
dedicated space missions.
| [
{
"created": "Tue, 23 Apr 2024 06:05:26 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Jun 2024 08:43:26 GMT",
"version": "v2"
}
] | 2024-06-04 | [
[
"Channuie",
"Phongpichit",
"",
"Walailak U."
]
] | Using suitable Renormalization Group (RG) based re-summation of quantum corrections to $R^2$ term, a re-summed version of the effective Lagrangian can be obtained \cite{Demmel:2015oqa}. In the context of gravity as an Asymptotically Safe (AS) theory, authors of Refs.\cite{Liu:2018hno,Koshelev:2022olc} proposed a refined Starobinsky model, $L_{\rm AS} = M^{2}_{p} R/2+(\alpha/2)R^{2}/[1+\beta \ln(R/\mu^{2})]$, where $R$ is the Ricci scalar, $\alpha$ and $\beta$ are constants and $\mu$ is an energy scale. In the present work, we embed this underlying effective Lagrangian within the framework of gravity's rainbow. By implementing the COBE normalization and the Planck constraint on the scalar spectrum, we demonstrate that the power spectrum of curvature perturbation relies on $\alpha$ and $\beta$, as well as on a rainbow parameter. Similarly, the scalar spectral index $n_s$ is influenced by $\beta$ and the rainbow parameter, yet remains unaffected by $\alpha$. Additionally, the tensor-to-scalar ratio $r$ solely depends on the rainbow parameter. Remarkably, when requiring $n_s$ to be consistent with the Planck collaboration at $1\sigma$ confidence level, the upper limit on the tensor-to-scalar ratio $r < 0.036$ can be naturally satisfied. This value potentially holds promise for potential measurement by Stage IV CMB ground experiments and is certainly within reach of future dedicated space missions. |
gr-qc/0109070 | Daniel Brown | Daniel Brown | The Time Vector: An Analysis of Continuity and Change | 46 pages, LaTeX2e, 2 figures | null | null | null | gr-qc | null | This paper sets out to explain: 1. Why the speed of light c is a constant and
is the maximum speed at which any moving entity can travel. 2. Why time elapsed
is different for a moving entity relative to a stationary entity. 3. Why there
has been confusion between the wave and particle nature of an entity. 4. The
relation between the speed of light c, Planck's constant k and time 5. An
expression for Mass using this notation 6. The derivation for De Broglie's
theorem 7. Indeterminacy of position
| [
{
"created": "Wed, 19 Sep 2001 18:36:53 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Jul 2002 12:28:53 GMT",
"version": "v2"
},
{
"created": "Mon, 25 Nov 2002 17:25:25 GMT",
"version": "v3"
},
{
"created": "Mon, 14 Apr 2003 07:49:38 GMT",
"version": "v4"
}
] | 2007-05-23 | [
[
"Brown",
"Daniel",
""
]
] | This paper sets out to explain: 1. Why the speed of light c is a constant and is the maximum speed at which any moving entity can travel. 2. Why time elapsed is different for a moving entity relative to a stationary entity. 3. Why there has been confusion between the wave and particle nature of an entity. 4. The relation between the speed of light c, Planck's constant k and time 5. An expression for Mass using this notation 6. The derivation for De Broglie's theorem 7. Indeterminacy of position |
gr-qc/0612018 | Paul R. Anderson | Paul R. Anderson and A. Fabbri | Apparent universality of semiclassical gravity in the far field limit | Title change, some details added, minor changes, acknowledgement
added, references added, 7 pages, no figures | Phys.Rev.D75:044015,2007 | 10.1103/PhysRevD.75.044015 | null | gr-qc hep-th | null | The universality of semiclassical gravity is investigated by considering the
behavior of the quantities < \phi^2 > and < {T^a}_b >, along with quantum
corrections to the effective Newtonian potential in the far field limits of
static spherically symmetric objects ranging from stars in the weak field
Newtonian limit to black holes. For scalar fields it is shown that when
differences occur they all result from the behavior of a single mode with zero
frequency and angular momentum and are thus due to a combination of infrared
and s-wave effects. An intriguing combination of similarities and differences
between the extreme cases of a Schwarzschild black hole and a star in the weak
field Newtonian limit is explained.
| [
{
"created": "Mon, 4 Dec 2006 18:15:22 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Mar 2007 14:00:49 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Anderson",
"Paul R.",
""
],
[
"Fabbri",
"A.",
""
]
] | The universality of semiclassical gravity is investigated by considering the behavior of the quantities < \phi^2 > and < {T^a}_b >, along with quantum corrections to the effective Newtonian potential in the far field limits of static spherically symmetric objects ranging from stars in the weak field Newtonian limit to black holes. For scalar fields it is shown that when differences occur they all result from the behavior of a single mode with zero frequency and angular momentum and are thus due to a combination of infrared and s-wave effects. An intriguing combination of similarities and differences between the extreme cases of a Schwarzschild black hole and a star in the weak field Newtonian limit is explained. |
1709.10504 | Ziad Sakr georges | Ziad Sakr, Alain Blanchard | Testing General Relativity from Curvature & Energy contents at
Cosmological scale | To appeear in the proceedings of the 52st Rencontres de Moriond | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we examine what are the cosmological implications of allowing
the geometrical curvature density to behave independently from the energy
density contents. Using the full data extracted by Planck mission from CMB,
combined with BAO and SNIa measurements, we derive, in the light of this
approach, new constraints on the cosmological parameters. In particular we
determine the behavior of the curvature dark energy degeneracy when allowing a
varying equation of state for the latter. We also examine whether this approach
could bridge the gap recently found between the Hubble parameter value
determined from CMB and that from the local universe measurements
| [
{
"created": "Fri, 29 Sep 2017 17:27:09 GMT",
"version": "v1"
}
] | 2017-10-02 | [
[
"Sakr",
"Ziad",
""
],
[
"Blanchard",
"Alain",
""
]
] | In this work we examine what are the cosmological implications of allowing the geometrical curvature density to behave independently from the energy density contents. Using the full data extracted by Planck mission from CMB, combined with BAO and SNIa measurements, we derive, in the light of this approach, new constraints on the cosmological parameters. In particular we determine the behavior of the curvature dark energy degeneracy when allowing a varying equation of state for the latter. We also examine whether this approach could bridge the gap recently found between the Hubble parameter value determined from CMB and that from the local universe measurements |
0907.1620 | Woei Chet Lim | A. A. Coley, S. Hervik, W. C. Lim, M. A. H. MacCallum | Properties of kinematic singularities | 13 pages. Published version. One sentence from version 2 corrected | Class.Quant.Grav.26:215008,2009 | 10.1088/0264-9381/26/21/215008 | AEI-2009-064 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The locally rotationally symmetric tilted perfect fluid Bianchi type V
cosmological model provides examples of future geodesically complete spacetimes
that admit a `kinematic singularity' at which the fluid congruence is
inextendible but all frame components of the Weyl and Ricci tensors remain
bounded. We show that for any positive integer n there are examples of Bianchi
type V spacetimes admitting a kinematic singularity such that the covariant
derivatives of the Weyl and Ricci tensors up to the n-th order also stay
bounded. We briefly discuss singularities in classical spacetimes.
| [
{
"created": "Thu, 9 Jul 2009 17:04:15 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Sep 2009 11:52:35 GMT",
"version": "v2"
},
{
"created": "Tue, 6 Oct 2009 13:58:21 GMT",
"version": "v3"
}
] | 2009-10-06 | [
[
"Coley",
"A. A.",
""
],
[
"Hervik",
"S.",
""
],
[
"Lim",
"W. C.",
""
],
[
"MacCallum",
"M. A. H.",
""
]
] | The locally rotationally symmetric tilted perfect fluid Bianchi type V cosmological model provides examples of future geodesically complete spacetimes that admit a `kinematic singularity' at which the fluid congruence is inextendible but all frame components of the Weyl and Ricci tensors remain bounded. We show that for any positive integer n there are examples of Bianchi type V spacetimes admitting a kinematic singularity such that the covariant derivatives of the Weyl and Ricci tensors up to the n-th order also stay bounded. We briefly discuss singularities in classical spacetimes. |
2107.11352 | Fil Simovic | Gareth Arturo Marks, Fil Simovic, Robert B. Mann | Phase Transitions in 4D Gauss-Bonnet-de Sitter Black Holes | 23 pages, 6 figures. Updated references | null | 10.1103/PhysRevD.104.104056 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate thermodynamic aspects of black holes in the recently
formulated four dimensional Gauss-Bonnet theory of gravity, focusing on its
asymptotically de Sitter ($\Lambda>0$) solutions. We take a Euclidean path
integral approach, where thermodynamic data is fixed at a finite radius
`cavity' outside the black hole to achieve equilibrium in the presence of the
cosmological horizon. Working in the extended phase space where the
cosmological constant is treated as a thermodynamic pressure, we study the
phase structure of both uncharged and charged solutions, uncovering a wealth of
phenomena. In the uncharged case, black holes are found to undergo either the
standard Hawking-Page-like transition to empty de Sitter space or a small-large
transition (akin to those seen in charged AdS black holes in pure Einstein
gravity) depending on the pressure. We also find a triple point where the
radiation, small, and large black hole phases coexist, and a zeroth-order phase
transition within a narrow range of Gauss-Bonnet coupling parameter. Reentrant
phase transitions between radiation and a small black hole also exist inside a
certain parameter range. Similar phenomena are found in the charged case, with
the charge parameter playing a role analogous to the Gauss-Bonnet coupling
parameter in determining the phase structure.
| [
{
"created": "Fri, 23 Jul 2021 17:10:47 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Aug 2021 21:48:13 GMT",
"version": "v2"
}
] | 2021-12-01 | [
[
"Marks",
"Gareth Arturo",
""
],
[
"Simovic",
"Fil",
""
],
[
"Mann",
"Robert B.",
""
]
] | We investigate thermodynamic aspects of black holes in the recently formulated four dimensional Gauss-Bonnet theory of gravity, focusing on its asymptotically de Sitter ($\Lambda>0$) solutions. We take a Euclidean path integral approach, where thermodynamic data is fixed at a finite radius `cavity' outside the black hole to achieve equilibrium in the presence of the cosmological horizon. Working in the extended phase space where the cosmological constant is treated as a thermodynamic pressure, we study the phase structure of both uncharged and charged solutions, uncovering a wealth of phenomena. In the uncharged case, black holes are found to undergo either the standard Hawking-Page-like transition to empty de Sitter space or a small-large transition (akin to those seen in charged AdS black holes in pure Einstein gravity) depending on the pressure. We also find a triple point where the radiation, small, and large black hole phases coexist, and a zeroth-order phase transition within a narrow range of Gauss-Bonnet coupling parameter. Reentrant phase transitions between radiation and a small black hole also exist inside a certain parameter range. Similar phenomena are found in the charged case, with the charge parameter playing a role analogous to the Gauss-Bonnet coupling parameter in determining the phase structure. |
gr-qc/0301003 | Matt Visser | Matt Visser (Victoria University of Wellington), Sayan Kar (Indian
Institute of Technology), and Naresh Dadhich (IUCAA, Pune) | Traversable wormholes with arbitrarily small energy condition violations | 4 pages, revtex4; V2: discussion refined and strengthened in view of
referee comments, no changes in physics conclusions. To appear in Physical
Review Letters | Phys.Rev.Lett.90:201102,2003 | 10.1103/PhysRevLett.90.201102 | null | gr-qc | null | Traversable wormholes necessarily require violations of the averaged null
energy condition; this being the definition of ``exotic matter''. However, the
theorems which guarantee the energy condition violation are remarkably silent
when it comes to making quantitative statements regarding the ``total amount''
of energy condition violating matter in the spacetime. We develop a suitable
measure for quantifying this notion, and demonstrate the existence of spacetime
geometries containing traversable wormholes that are supported by arbitrarily
small quantities of ``exotic matter''.
| [
{
"created": "Wed, 1 Jan 2003 19:44:42 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Apr 2003 02:14:32 GMT",
"version": "v2"
}
] | 2011-07-18 | [
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
],
[
"Kar",
"Sayan",
"",
"Indian\n Institute of Technology"
],
[
"Dadhich",
"Naresh",
"",
"IUCAA, Pune"
]
] | Traversable wormholes necessarily require violations of the averaged null energy condition; this being the definition of ``exotic matter''. However, the theorems which guarantee the energy condition violation are remarkably silent when it comes to making quantitative statements regarding the ``total amount'' of energy condition violating matter in the spacetime. We develop a suitable measure for quantifying this notion, and demonstrate the existence of spacetime geometries containing traversable wormholes that are supported by arbitrarily small quantities of ``exotic matter''. |
1601.05902 | Hamed Pejhan | Hamed Pejhan and Surena Rahbardehghan | Casimir energy-momentum tensor for a quantized bulk scalar field in the
geometry of two curved branes on Friedmann-Robertson-Walker background | 10 pages | Phys. Rev. D 94,064034 (2016) | 10.1103/PhysRevD.94.064034 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a previous work [S. Rahbardehghan et al. in Phys. Lett. B 750, 627
(2015)], we considered a simple brane-world model; a single $4$-dimensional
brane embedded in a $5$-dimensional de Sitter (dS) space-time. Then, by
including a conformally coupled scalar field in the bulk, we studied the
induced Casimir energy-momentum tensor. Technically, the Krein-Gupta-Bleuler
(KGB) quantization scheme as a covariant and renormalizable quantum field
theory in dS space was used to perform the calculations. In the present paper,
we generalize this study to a less idealized, but physically motivated,
scenario, namely we consider Friedmann-Robertson-Walker (FRW) space-time which
behaves asymptotically as a dS space-time. More precisely, we evaluate Casimir
energy-momentum tensor for a system with two $D$-dimensional curved branes on
background of $D+1$-dimensional FRW space-time with negative spatial curvature
and a conformally coupled bulk scalar field that satisfies Dirichlet boundary
condition on the branes.
| [
{
"created": "Fri, 22 Jan 2016 08:05:31 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Jan 2016 06:22:16 GMT",
"version": "v2"
},
{
"created": "Wed, 14 Sep 2016 10:09:36 GMT",
"version": "v3"
}
] | 2016-12-21 | [
[
"Pejhan",
"Hamed",
""
],
[
"Rahbardehghan",
"Surena",
""
]
] | In a previous work [S. Rahbardehghan et al. in Phys. Lett. B 750, 627 (2015)], we considered a simple brane-world model; a single $4$-dimensional brane embedded in a $5$-dimensional de Sitter (dS) space-time. Then, by including a conformally coupled scalar field in the bulk, we studied the induced Casimir energy-momentum tensor. Technically, the Krein-Gupta-Bleuler (KGB) quantization scheme as a covariant and renormalizable quantum field theory in dS space was used to perform the calculations. In the present paper, we generalize this study to a less idealized, but physically motivated, scenario, namely we consider Friedmann-Robertson-Walker (FRW) space-time which behaves asymptotically as a dS space-time. More precisely, we evaluate Casimir energy-momentum tensor for a system with two $D$-dimensional curved branes on background of $D+1$-dimensional FRW space-time with negative spatial curvature and a conformally coupled bulk scalar field that satisfies Dirichlet boundary condition on the branes. |
2007.06671 | Sam Patrick | Sam Patrick | Quasinormal modes in dispersive black hole analogues | 22 pages, 10 figures | null | null | null | gr-qc physics.flu-dyn | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by analogue models of black holes, a scheme is developed to analyse
multi-mode scattering processes in dispersive, inhomogeneous media. The scheme
is applied to the scattering of weakly dispersive gravity waves with a
rotating, draining vortex flow, which captures many features of a rotating
black hole spacetime. In particular, the quasinormal mode spectrum is computed
and shown to deviate from the non-dispersive case for the co-rotating modes in
the system.
| [
{
"created": "Mon, 13 Jul 2020 20:25:37 GMT",
"version": "v1"
}
] | 2020-07-15 | [
[
"Patrick",
"Sam",
""
]
] | Motivated by analogue models of black holes, a scheme is developed to analyse multi-mode scattering processes in dispersive, inhomogeneous media. The scheme is applied to the scattering of weakly dispersive gravity waves with a rotating, draining vortex flow, which captures many features of a rotating black hole spacetime. In particular, the quasinormal mode spectrum is computed and shown to deviate from the non-dispersive case for the co-rotating modes in the system. |
1808.00673 | Madhavan Varadarajan | Madhavan Varadarajan | From Euclidean to Lorentzian Loop Quantum Gravity via a Positive
Complexifier | minor modification to section 5.2 | null | 10.1088/1361-6382/aaf2cd | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct a positive complexifier, differentiable almost everywhere on the
classical phase space of real triads and $SU(2)$ connections, which generates a
Wick Transform from Euclidean to Lorentzian gravity everywhere except on a
phase space set of measure zero. This Wick transform assigns an equal role to
the self dual and anti-self dual Ashtekar variables in quantum theory. We argue
that the appropriate quantum arena for an analysis of the properties of the
Wick rotation is the diffeomorphism invariant Hilbert space of Loop Quantum
Gravity (LQG) rather than its kinematic Hilbert space. We examine issues
related to the construction, in quantum theory, of the positive complexifier as
a positive operator on this diffeomorphism invariant Hilbert space. Assuming
the existence of such an operator, we explore the possibility of identifying
physical states in Lorentzian LQG as Wick rotated images of physical states in
the Euclidean theory. Our considerations derive from Thiemann's remarkable
proposal to define Lorentzian LQG from Euclidean LQG via the implementation in
quantum theory of a phase space `Wick rotation' which maps real
Ashtekar-Barbero variables to Ashtekar's complex, self dual variables.
| [
{
"created": "Thu, 2 Aug 2018 05:53:04 GMT",
"version": "v1"
},
{
"created": "Sun, 5 Aug 2018 07:13:20 GMT",
"version": "v2"
}
] | 2019-05-22 | [
[
"Varadarajan",
"Madhavan",
""
]
] | We construct a positive complexifier, differentiable almost everywhere on the classical phase space of real triads and $SU(2)$ connections, which generates a Wick Transform from Euclidean to Lorentzian gravity everywhere except on a phase space set of measure zero. This Wick transform assigns an equal role to the self dual and anti-self dual Ashtekar variables in quantum theory. We argue that the appropriate quantum arena for an analysis of the properties of the Wick rotation is the diffeomorphism invariant Hilbert space of Loop Quantum Gravity (LQG) rather than its kinematic Hilbert space. We examine issues related to the construction, in quantum theory, of the positive complexifier as a positive operator on this diffeomorphism invariant Hilbert space. Assuming the existence of such an operator, we explore the possibility of identifying physical states in Lorentzian LQG as Wick rotated images of physical states in the Euclidean theory. Our considerations derive from Thiemann's remarkable proposal to define Lorentzian LQG from Euclidean LQG via the implementation in quantum theory of a phase space `Wick rotation' which maps real Ashtekar-Barbero variables to Ashtekar's complex, self dual variables. |
gr-qc/9907038 | William Krivan | William Krivan (University of Utah) | Late-Time Dynamics of Scalar Fields on Rotating Black Hole Backgrounds | 4 pages, 4 Encapsulated Postscript figures, submitted to Phys. Rev. D | Phys.Rev.D60:101501,1999 | 10.1103/PhysRevD.60.101501 | null | gr-qc | null | Motivated by results of recent analytic studies, we present a numerical
investigation of the late-time dynamics of scalar test fields on Kerr
backgrounds. We pay particular attention to the issue of mixing of different
multipoles and their fall-off behavior at late times. Confining ourselves to
the special case of axisymmetric modes with equatorial symmetry, we show that,
in agreement with the results of previous work, the late-time behavior is
dominated by the lowest allowed l-multipole. However the numerical results
imply that, in general, the late-time fall-off of the dominating multipole is
different from that in the Schwarzschild case, and seems to be incompatible
with a result of a recently published analytic study.
| [
{
"created": "Thu, 8 Jul 1999 22:38:47 GMT",
"version": "v1"
}
] | 2009-12-30 | [
[
"Krivan",
"William",
"",
"University of Utah"
]
] | Motivated by results of recent analytic studies, we present a numerical investigation of the late-time dynamics of scalar test fields on Kerr backgrounds. We pay particular attention to the issue of mixing of different multipoles and their fall-off behavior at late times. Confining ourselves to the special case of axisymmetric modes with equatorial symmetry, we show that, in agreement with the results of previous work, the late-time behavior is dominated by the lowest allowed l-multipole. However the numerical results imply that, in general, the late-time fall-off of the dominating multipole is different from that in the Schwarzschild case, and seems to be incompatible with a result of a recently published analytic study. |
2005.10065 | Daniel Galviz Blanco | Daniel D. Sega and Daniel Galviz | Are the notions of past, present and future compatible with the General
Theory of Relativity? | There are some issues with the physics interpretation that leads to a
wrong perception of A-theory. The authors found with correction of these
issues hints that point out the fundamentality of B-theory. However, similar
arguments were already pointed out in previous literature | null | null | null | gr-qc physics.hist-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The notions of time and causality are revisited, as well as the A- and
B-theory of time, in order to determine which theory of time is most compatible
with relativistic spacetimes. By considering orientable spacetimes and defining
a time-orientation, we formalize the concepts of a time-series in relativistic
spacetimes; A-theory and B-theory are given mathematical descriptions within
the formalism of General Relativity. As a result, in time-orientable
spacetimes, the notions of events being in the future and in the past, which
are notions of A-theory, are found to be more fundamental than the notions of
events being earlier than or later than other events, which are notions of
B-theory. Furthermore, we find that B-theory notions are incompatible with some
structures encountered in globally hyperbolic spacetimes, namely past and
future inextendible curves. Hence, GR is favorable to A-theory and the notions
of past, present and future.
| [
{
"created": "Wed, 20 May 2020 14:20:56 GMT",
"version": "v1"
},
{
"created": "Fri, 29 May 2020 17:10:24 GMT",
"version": "v2"
},
{
"created": "Wed, 8 Sep 2021 10:35:14 GMT",
"version": "v3"
}
] | 2021-09-09 | [
[
"Sega",
"Daniel D.",
""
],
[
"Galviz",
"Daniel",
""
]
] | The notions of time and causality are revisited, as well as the A- and B-theory of time, in order to determine which theory of time is most compatible with relativistic spacetimes. By considering orientable spacetimes and defining a time-orientation, we formalize the concepts of a time-series in relativistic spacetimes; A-theory and B-theory are given mathematical descriptions within the formalism of General Relativity. As a result, in time-orientable spacetimes, the notions of events being in the future and in the past, which are notions of A-theory, are found to be more fundamental than the notions of events being earlier than or later than other events, which are notions of B-theory. Furthermore, we find that B-theory notions are incompatible with some structures encountered in globally hyperbolic spacetimes, namely past and future inextendible curves. Hence, GR is favorable to A-theory and the notions of past, present and future. |
2308.01784 | Aleksander Kozak | Aleksander Kozak, Aneta Wojnar | Earthquakes as probing tools for gravity theories | 6 pages, 3 figures | null | null | null | gr-qc astro-ph.EP | http://creativecommons.org/licenses/by/4.0/ | We propose a novel method for testing gravity models using seismic data from
Earth. By imposing observational constraints on Earth's moment of inertia and
mass, we rigorously limit the gravitational models' parameters within a
$2\sigma$ accuracy. Our method constrains the parameters governing additional
terms to the General Relativity Lagrangian to the following ranges:
$-2\times10^9\lesssim\beta\lesssim 10^9 \text{m}^2$ for Palatini $f(R)$
gravity, $-8\times10^9\lesssim\epsilon\lesssim 4\times 10^9 \text{m}^2$ for
Eddington-inspired Born-Infeld gravity, and
$-10^{-3}\lesssim\Upsilon\lesssim10^{-3}$ for Degenerate Higher-Order
Scalar-Tensor theories. We also discuss potential avenues to enhance the
proposed method, aiming to impose even tighter constraints on gravity models.
| [
{
"created": "Thu, 3 Aug 2023 14:23:33 GMT",
"version": "v1"
}
] | 2023-08-04 | [
[
"Kozak",
"Aleksander",
""
],
[
"Wojnar",
"Aneta",
""
]
] | We propose a novel method for testing gravity models using seismic data from Earth. By imposing observational constraints on Earth's moment of inertia and mass, we rigorously limit the gravitational models' parameters within a $2\sigma$ accuracy. Our method constrains the parameters governing additional terms to the General Relativity Lagrangian to the following ranges: $-2\times10^9\lesssim\beta\lesssim 10^9 \text{m}^2$ for Palatini $f(R)$ gravity, $-8\times10^9\lesssim\epsilon\lesssim 4\times 10^9 \text{m}^2$ for Eddington-inspired Born-Infeld gravity, and $-10^{-3}\lesssim\Upsilon\lesssim10^{-3}$ for Degenerate Higher-Order Scalar-Tensor theories. We also discuss potential avenues to enhance the proposed method, aiming to impose even tighter constraints on gravity models. |
0711.3538 | Nakia Carlevaro | Nakia Carlevaro, Orchidea Maria Lecian, Giovanni Montani | Macroscopic and Microscopic Paradigms for the Torsion Field: from the
Test-Particle Motion to a Lorentz Gauge Theory | 15 pages, no figures, invited paper | Ann. Fond. L. de Broglie 32, 281-295 (2007) | null | null | gr-qc astro-ph hep-th | null | Torsion represents the most natural extension of General Relativity and it
attracted interest over the years in view of its link with fundamental
properties of particle motion. The bulk of the approaches concerning the
torsion dynamics focus their attention on their geometrical nature and they are
naturally led to formulate a non-propagating theory.
Here we review two different paradigms to describe the role of the torsion
field, as far as a propagating feature of the resulting dynamics is concerned.
However, these two proposals deal with different pictures, i.e., a macroscopic
approach, based on the construction of suitable potentials for the torsion
field, and a microscopic approach, which relies on the identification of
torsion with the gauge field associated with the local Lorentz symmetry. We
analyze in some detail both points of view and their implications on the
coupling between torsion and matter will be investigated. In particular, in the
macroscopic case, we analyze the test-particle motion to fix the physical
trajectory, while, in the microscopic approach, a natural coupling between
torsion and the spin momentum of matter fields arises.
| [
{
"created": "Thu, 22 Nov 2007 10:37:48 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Dec 2007 12:11:30 GMT",
"version": "v2"
}
] | 2009-03-24 | [
[
"Carlevaro",
"Nakia",
""
],
[
"Lecian",
"Orchidea Maria",
""
],
[
"Montani",
"Giovanni",
""
]
] | Torsion represents the most natural extension of General Relativity and it attracted interest over the years in view of its link with fundamental properties of particle motion. The bulk of the approaches concerning the torsion dynamics focus their attention on their geometrical nature and they are naturally led to formulate a non-propagating theory. Here we review two different paradigms to describe the role of the torsion field, as far as a propagating feature of the resulting dynamics is concerned. However, these two proposals deal with different pictures, i.e., a macroscopic approach, based on the construction of suitable potentials for the torsion field, and a microscopic approach, which relies on the identification of torsion with the gauge field associated with the local Lorentz symmetry. We analyze in some detail both points of view and their implications on the coupling between torsion and matter will be investigated. In particular, in the macroscopic case, we analyze the test-particle motion to fix the physical trajectory, while, in the microscopic approach, a natural coupling between torsion and the spin momentum of matter fields arises. |
1312.2670 | Narayan Banerjee | Nandan Roy and narayan Banerjee | Tracking quintessence: a dynamical systems study | 10 pages, 3 figures; Accepted for publication in Gen. Relativ. Gravit | null | 10.1007/s10714-013-1651-5 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | With the tracking condition, the stability of quintessence solutions are
examined. It is found that there is only one physically relevant fixed point
for the system generically. Two specific examples of quintessence potentials
are worked out in the frame work.
| [
{
"created": "Tue, 10 Dec 2013 05:19:12 GMT",
"version": "v1"
}
] | 2013-12-11 | [
[
"Roy",
"Nandan",
""
],
[
"Banerjee",
"narayan",
""
]
] | With the tracking condition, the stability of quintessence solutions are examined. It is found that there is only one physically relevant fixed point for the system generically. Two specific examples of quintessence potentials are worked out in the frame work. |
gr-qc/0505083 | Jonas Mureika | J. R. Mureika and C. C. Dyer | Multifractal Analysis of Packed Swiss Cheese Cosmologies | 3 latex files, 18 ps figures | Gen. Rel. Gravit. 36 (2004) 151-184 | 10.1023/B:GERG.0000006699.45969.49 | null | gr-qc | null | The multifractal spectrum of various three-dimensional representations of
Packed Swiss Cheese cosmologies in open, closed, and flat spaces are measured,
and it is determined that the curvature of the space does not alter the
associated fractal structure. These results are compared to observational data
and simulated models of large scale galaxy clustering, to assess the viability
of the PSC as a candidate for such structure formation. It is found that the
PSC dimension spectra do not match those of observation, and possible solutions
to this discrepancy are offered, including accounting for potential luminosity
biasing effects. Various random and uniform sets are also analyzed to provide
insight into the meaning of the multifractal spectrum as it relates to the
observed scaling behaviors.
| [
{
"created": "Tue, 17 May 2005 16:02:44 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Mureika",
"J. R.",
""
],
[
"Dyer",
"C. C.",
""
]
] | The multifractal spectrum of various three-dimensional representations of Packed Swiss Cheese cosmologies in open, closed, and flat spaces are measured, and it is determined that the curvature of the space does not alter the associated fractal structure. These results are compared to observational data and simulated models of large scale galaxy clustering, to assess the viability of the PSC as a candidate for such structure formation. It is found that the PSC dimension spectra do not match those of observation, and possible solutions to this discrepancy are offered, including accounting for potential luminosity biasing effects. Various random and uniform sets are also analyzed to provide insight into the meaning of the multifractal spectrum as it relates to the observed scaling behaviors. |
1910.11017 | Jibril Ben Achour | Jibril Ben Achour, Hongguang Liu, Shinji Mukohyama | Hairy black holes in DHOST theories: Exploring disformal transformation
as a solution-generating method | 33 pages, 8 figures, matched the published version in JCAP | null | 10.1088/1475-7516/2020/02/023 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Solutions-generating methods based on field redefinitions, such as conformal
mapping, play an important role in investigating exact solutions in modified
gravity. In this work, we explore the possibility to use disformal field
redefinitions to investigate new regions of the solution space of DHOST
theories. The crucial ingredient is to find suitable seed solutions to generate
new exact ones for DHOST theories. We first consider a seed solution of the
Einstein-Scalar system describing a naked singularity. Under suitable
assumptions, we derive a no-go result showing that no black hole solution can
be constructed from such a seed GR solution. Then, taking into account the
stability of each degeneracy classes of quadratic DHOST theories under a
general disformal mapping, we consider two kinds of known black hole solutions
as seed configurations: the Schwarzschild stealth solution and the non-stealth
Reissner-Nordstrom like solution. Restricting our considerations to invertible
disformal transformations, we show that building new hairy black hole solutions
from the stealth solution associated to a constant kinetic term is also quite
constrained. We obtain new solutions which either are stealth or describe
asymptotically locally flat black holes with a deficit solid angle. However,
starting from the non-stealth seed solution associated to a non constant
kinetic term as well as a time-dependent scalar profile, we show that a
disformal transformation can introduce rather general modifications of the
exterior geometry. Finally, we consider the construction of minimally modified
hairy black hole solutions using a small disformal transformation. Further
applications of this solution generating method should allow to provide new
hairy rotating black hole solutions beyond the stealth sector useful for
phenomenological investigations of compact objects beyond GR.
| [
{
"created": "Thu, 24 Oct 2019 10:27:46 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Nov 2019 14:41:22 GMT",
"version": "v2"
},
{
"created": "Wed, 5 Feb 2020 15:03:06 GMT",
"version": "v3"
}
] | 2020-03-04 | [
[
"Achour",
"Jibril Ben",
""
],
[
"Liu",
"Hongguang",
""
],
[
"Mukohyama",
"Shinji",
""
]
] | Solutions-generating methods based on field redefinitions, such as conformal mapping, play an important role in investigating exact solutions in modified gravity. In this work, we explore the possibility to use disformal field redefinitions to investigate new regions of the solution space of DHOST theories. The crucial ingredient is to find suitable seed solutions to generate new exact ones for DHOST theories. We first consider a seed solution of the Einstein-Scalar system describing a naked singularity. Under suitable assumptions, we derive a no-go result showing that no black hole solution can be constructed from such a seed GR solution. Then, taking into account the stability of each degeneracy classes of quadratic DHOST theories under a general disformal mapping, we consider two kinds of known black hole solutions as seed configurations: the Schwarzschild stealth solution and the non-stealth Reissner-Nordstrom like solution. Restricting our considerations to invertible disformal transformations, we show that building new hairy black hole solutions from the stealth solution associated to a constant kinetic term is also quite constrained. We obtain new solutions which either are stealth or describe asymptotically locally flat black holes with a deficit solid angle. However, starting from the non-stealth seed solution associated to a non constant kinetic term as well as a time-dependent scalar profile, we show that a disformal transformation can introduce rather general modifications of the exterior geometry. Finally, we consider the construction of minimally modified hairy black hole solutions using a small disformal transformation. Further applications of this solution generating method should allow to provide new hairy rotating black hole solutions beyond the stealth sector useful for phenomenological investigations of compact objects beyond GR. |
1510.02085 | Hossein Mohseni Sadjadi | H. Mohseni Sadjadi | Onset of acceleration in a Universe initially filled by dark and
baryonic matters in nonminimally coupled teleparallel model | 16 pages, 3 figures, accepted for publication in Physical Review D | Phys. Rev. D 92, 123538 (2015) | 10.1103/PhysRevD.92.123538 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A nonminimally coupled quintessence dark energy in teleparallel model of
gravity is considered. It is clarified how a matter dominated universe with
initial negligible dark energy density can evolve to a late time de Sitter
space-time via the $Z_2$ symmetry breaking.
| [
{
"created": "Wed, 7 Oct 2015 13:15:19 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Nov 2015 11:09:29 GMT",
"version": "v2"
},
{
"created": "Sun, 13 Dec 2015 07:52:10 GMT",
"version": "v3"
},
{
"created": "Tue, 22 Dec 2015 11:38:21 GMT",
"version": "v4"
}
] | 2016-01-06 | [
[
"Sadjadi",
"H. Mohseni",
""
]
] | A nonminimally coupled quintessence dark energy in teleparallel model of gravity is considered. It is clarified how a matter dominated universe with initial negligible dark energy density can evolve to a late time de Sitter space-time via the $Z_2$ symmetry breaking. |
0707.0708 | Owen Pavel Fernandez Piedra | Owen Pavel Fernandez Piedra and Alejandro Cabo Montes de Oca | Vacuum polarization of massive spinor fields in static black-string
backgrounds | 15 pages, few corrections are done in this version | Phys.Rev.D77:024044,2008 | 10.1103/PhysRevD.77.024044 | null | gr-qc | null | The renormalized mean value of the quantum Lagrangian and the corresponding
components of the Energy-Momentum tensor for massive spinor fields coupled to
an arbitrary gravitational field configuration having cylindrical symmetry are
analytically evaluated using the Schwinger-DeWitt approximation, up to second
order in the inverse mass value. The general results are employed to explicitly
derive compact analytical expressions for the quantum mean Lagrangian and
Energy- Momentum tensor in the particular background of the Black-String
space-time.
| [
{
"created": "Wed, 4 Jul 2007 22:55:23 GMT",
"version": "v1"
},
{
"created": "Sun, 2 Sep 2007 15:54:02 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Piedra",
"Owen Pavel Fernandez",
""
],
[
"de Oca",
"Alejandro Cabo Montes",
""
]
] | The renormalized mean value of the quantum Lagrangian and the corresponding components of the Energy-Momentum tensor for massive spinor fields coupled to an arbitrary gravitational field configuration having cylindrical symmetry are analytically evaluated using the Schwinger-DeWitt approximation, up to second order in the inverse mass value. The general results are employed to explicitly derive compact analytical expressions for the quantum mean Lagrangian and Energy- Momentum tensor in the particular background of the Black-String space-time. |
2312.06878 | Mir Mehedi Faruk | Mir Mehedi Faruk, Edward Morvan, Jan Pieter van der Schaar | Static sphere observers and geodesics in Schwarzschild-de Sitter
spacetime | null | JCAP 05 (2024) 118 | 10.1088/1475-7516/2024/05/118 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We analyze null- and spacelike radial geodesics in Schwarzschild-de Sitter
spacetime connecting two conjugate static sphere observers, i.e. free-falling
observers at a fixed radius in between the two horizons. We explicitly
determine the changes in the causal structure with respect to these natural
observers as a result of the inward bending of the black hole singularity, as
well as the outward bending of asymptotic infinity. Notably, the inward and
outward bending changes as a function of the black hole mass, first increasing
towards a maximum and then decreasing to vanish in the extreme Nariai limit.
For a generic mass of the black hole this implies the existence of finite size
(temporal) windows for the presence of symmetric radial geodesics between the
static sphere observers probing the interior region of the black hole, as well
as the exterior de Sitter region. We determine the size of the interior (black
hole) and exterior (de Sitter) temporal windows in $4$, $5$ and $6$ spacetime
dimensions, finding that they are equal in $D=5$, and compute the proper
lengths of the symmetric radial geodesics. We comment on the implications for
information exchange and the potential role of the symmetric radial geodesics
in a geodesic approximation of static sphere correlators in Schwarzschild-de
Sitter spacetime.
| [
{
"created": "Mon, 11 Dec 2023 23:03:37 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Feb 2024 22:35:06 GMT",
"version": "v2"
},
{
"created": "Tue, 30 Apr 2024 12:03:52 GMT",
"version": "v3"
}
] | 2024-06-04 | [
[
"Faruk",
"Mir Mehedi",
""
],
[
"Morvan",
"Edward",
""
],
[
"van der Schaar",
"Jan Pieter",
""
]
] | We analyze null- and spacelike radial geodesics in Schwarzschild-de Sitter spacetime connecting two conjugate static sphere observers, i.e. free-falling observers at a fixed radius in between the two horizons. We explicitly determine the changes in the causal structure with respect to these natural observers as a result of the inward bending of the black hole singularity, as well as the outward bending of asymptotic infinity. Notably, the inward and outward bending changes as a function of the black hole mass, first increasing towards a maximum and then decreasing to vanish in the extreme Nariai limit. For a generic mass of the black hole this implies the existence of finite size (temporal) windows for the presence of symmetric radial geodesics between the static sphere observers probing the interior region of the black hole, as well as the exterior de Sitter region. We determine the size of the interior (black hole) and exterior (de Sitter) temporal windows in $4$, $5$ and $6$ spacetime dimensions, finding that they are equal in $D=5$, and compute the proper lengths of the symmetric radial geodesics. We comment on the implications for information exchange and the potential role of the symmetric radial geodesics in a geodesic approximation of static sphere correlators in Schwarzschild-de Sitter spacetime. |
2007.09196 | Daniel Boyanovsky | Mudit Rai, Daniel Boyanovsky | On the origin of entropy of gravitationally produced dark matter: the
entanglement entropy | published version | Phys. Rev. D 102, 063532 (2020) | 10.1103/PhysRevD.102.063532 | null | gr-qc astro-ph.CO hep-ph hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the emergence of entropy in gravitational production of dark matter
particles, ultra light scalars minimally coupled to gravity and heavier
fermions, from inflation to radiation domination (RD). Initial conditions
correspond to dark matter fields in their Bunch-Davies vacua during inflation.
The "out" states are correlated particle-antiparticle pairs, and the
distribution function is found in both cases. In the adiabatic regime the
density matrix features rapid decoherence by dephasing from interference
effects in the basis of "out" particle states, effectively reducing it to a
diagonal form with a concomitant von Neumann entropy. We show that it is
exactly the entanglement entropy obtained by tracing over one member of the
correlated pairs. Remarkably, for both statistics the entanglement entropy is
similar to the quantum kinetic entropy in terms of the distribution function
with noteworthy differences stemming from pair correlations. The entropy and
the kinetic fluid form of the energy momentum tensor all originate from
decoherence of the density matrix. For ultra light scalar dark matter, the
distribution function peaks at low momentum $\propto 1/k^3$ and the specific
entropy is $\ll 1$. This is a hallmark of a \emph{condensed phase} but with
vanishing field expectation value. For fermionic dark matter the distribution
function is nearly thermal and the specific entropy is $\mathcal{O}(1)$ typical
of a thermal species. We argue that the functional form of the entanglement
entropy is quite general and applies to alternative production mechanisms such
as parametric amplification during reheating.
| [
{
"created": "Fri, 17 Jul 2020 19:26:36 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Sep 2020 18:21:14 GMT",
"version": "v2"
}
] | 2020-09-30 | [
[
"Rai",
"Mudit",
""
],
[
"Boyanovsky",
"Daniel",
""
]
] | We study the emergence of entropy in gravitational production of dark matter particles, ultra light scalars minimally coupled to gravity and heavier fermions, from inflation to radiation domination (RD). Initial conditions correspond to dark matter fields in their Bunch-Davies vacua during inflation. The "out" states are correlated particle-antiparticle pairs, and the distribution function is found in both cases. In the adiabatic regime the density matrix features rapid decoherence by dephasing from interference effects in the basis of "out" particle states, effectively reducing it to a diagonal form with a concomitant von Neumann entropy. We show that it is exactly the entanglement entropy obtained by tracing over one member of the correlated pairs. Remarkably, for both statistics the entanglement entropy is similar to the quantum kinetic entropy in terms of the distribution function with noteworthy differences stemming from pair correlations. The entropy and the kinetic fluid form of the energy momentum tensor all originate from decoherence of the density matrix. For ultra light scalar dark matter, the distribution function peaks at low momentum $\propto 1/k^3$ and the specific entropy is $\ll 1$. This is a hallmark of a \emph{condensed phase} but with vanishing field expectation value. For fermionic dark matter the distribution function is nearly thermal and the specific entropy is $\mathcal{O}(1)$ typical of a thermal species. We argue that the functional form of the entanglement entropy is quite general and applies to alternative production mechanisms such as parametric amplification during reheating. |
1901.09163 | Muhammad Fitrah Alfian Rangga Sakti | M. F. A. R. Sakti, A. Suroso and F. P. Zen | Kerr-Newman-NUT-Kiselev black holes in Rastall theory of gravity and
Kerr/CFT Correspondence | 25 pages, title and abstract are changed, major revision, accepted in
Annals of Physics | Annals of Physics (2020), 413, 168062 | 10.1016/j.aop.2019.168062 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new twisted rotating black hole solution by performing
Demia{\'n}ski-Newman-Janis algorithm to the electrically and dyonically charged
black hole with quintessence in Rastall theory of gravity. Using our black hole
solution, we argue that Rastall gravity is not equivalent with Einstein
gravity. For further explanation, the black hole properties such as the horizon
and ergosphere are studied for which there are some different properties for
those theories. Some thermodynamic properties of the black hole solution are
also discussed. At the end, considering the Kerr/CFT correspondence is valid
for our black hole solution, the central charge from the CFT of this extremal
solution is derived.
| [
{
"created": "Sat, 26 Jan 2019 05:00:14 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Sep 2019 13:59:53 GMT",
"version": "v2"
},
{
"created": "Thu, 26 Dec 2019 11:03:27 GMT",
"version": "v3"
}
] | 2020-01-10 | [
[
"Sakti",
"M. F. A. R.",
""
],
[
"Suroso",
"A.",
""
],
[
"Zen",
"F. P.",
""
]
] | We present a new twisted rotating black hole solution by performing Demia{\'n}ski-Newman-Janis algorithm to the electrically and dyonically charged black hole with quintessence in Rastall theory of gravity. Using our black hole solution, we argue that Rastall gravity is not equivalent with Einstein gravity. For further explanation, the black hole properties such as the horizon and ergosphere are studied for which there are some different properties for those theories. Some thermodynamic properties of the black hole solution are also discussed. At the end, considering the Kerr/CFT correspondence is valid for our black hole solution, the central charge from the CFT of this extremal solution is derived. |
1812.05403 | Jorge Pullin | Rodolfo Gambini, Esteban Mato, Javier Olmedo, Jorge Pullin | Classical axisymmetric gravity in real Ashtekar variables | 14 pages, no figures, RevTex. Published version | Classical and Quantum Gravity 36 (2019) 125009 | 10.1088/1361-6382/ab1d82 | LSU-REL-121318 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We formulate axisymmetric general relativity in terms of real
Ashtekar--Barbero variables. We study the constraints and equations of motion
and show how the Kerr, Schwarzschild and Minkowski solutions arise. We also
discuss boundary conditions. This opens the possibility of a midisuperspace
quantization using loop quantum gravity techniques for spacetimes with axial
symmetry and time dependence.
| [
{
"created": "Thu, 13 Dec 2018 13:06:20 GMT",
"version": "v1"
},
{
"created": "Thu, 30 May 2019 18:35:09 GMT",
"version": "v2"
}
] | 2019-06-03 | [
[
"Gambini",
"Rodolfo",
""
],
[
"Mato",
"Esteban",
""
],
[
"Olmedo",
"Javier",
""
],
[
"Pullin",
"Jorge",
""
]
] | We formulate axisymmetric general relativity in terms of real Ashtekar--Barbero variables. We study the constraints and equations of motion and show how the Kerr, Schwarzschild and Minkowski solutions arise. We also discuss boundary conditions. This opens the possibility of a midisuperspace quantization using loop quantum gravity techniques for spacetimes with axial symmetry and time dependence. |
1803.10701 | Roberto Cotesta | Roberto Cotesta, Alessandra Buonanno, Alejandro Boh\'e, Andrea
Taracchini, Ian Hinder, Serguei Ossokine | Enriching the Symphony of Gravitational Waves from Binary Black Holes by
Tuning Higher Harmonics | 28 pages. Version that matches published article | Phys. Rev. D 98, 084028 (2018) | 10.1103/PhysRevD.98.084028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For the first time, we construct an inspiral-merger-ringdown waveform model
within the effective-one-body formalism for spinning, nonprecessing binary
black holes that includes gravitational modes beyond the dominant $(\ell,|m|) =
(2,2)$ mode, specifically $(\ell,|m|)=(2,1),(3,3),(4,4),(5,5)$. Our multipolar
waveform model incorporates recent (resummed) post-Newtonian results for the
inspiral and information from 157 numerical-relativity simulations, and 13
waveforms from black-hole perturbation theory for the (plunge-)merger and
ringdown. We quantify the improved accuracy including higher-order modes by
computing the faithfulness of the waveform model against the
numerical-relativity waveforms used to construct the model. We define the
faithfulness as the match maximized over time, phase of arrival,
gravitational-wave polarization and sky position of the waveform model, and
averaged over binary orientation, gravitational-wave polarization and sky
position of the numerical-relativity waveform. When the waveform model contains
only the $(2,2)$ mode, we find that the averaged faithfulness to
numerical-relativity waveforms containing all modes with $\ell \leq$ 5 ranges
from $90\%$ to $99.9\%$ for binaries with total mass $20-200 M_\odot$ (using
the Advanced LIGO's design noise curve). By contrast, when the
$(2,1),(3,3),(4,4),(5,5)$ modes are also included in the model, the
faithfulness improves to $99\%$ for all but four configurations in the
numerical-relativity catalog, for which the faithfulness is greater than
$98.5\%$. Using our results, we also develop also a (stand-alone) waveform
model for the merger-ringdown signal, calibrated to numerical-relativity
waveforms, which can be used to measure multiple quasi-normal modes. The
multipolar waveform model can be extended to include spin-precession, and will
be employed in upcoming observing runs of Advanced LIGO and Virgo.
| [
{
"created": "Wed, 28 Mar 2018 16:02:50 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Jul 2022 14:13:29 GMT",
"version": "v2"
}
] | 2022-07-22 | [
[
"Cotesta",
"Roberto",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Bohé",
"Alejandro",
""
],
[
"Taracchini",
"Andrea",
""
],
[
"Hinder",
"Ian",
""
],
[
"Ossokine",
"Serguei",
""
]
] | For the first time, we construct an inspiral-merger-ringdown waveform model within the effective-one-body formalism for spinning, nonprecessing binary black holes that includes gravitational modes beyond the dominant $(\ell,|m|) = (2,2)$ mode, specifically $(\ell,|m|)=(2,1),(3,3),(4,4),(5,5)$. Our multipolar waveform model incorporates recent (resummed) post-Newtonian results for the inspiral and information from 157 numerical-relativity simulations, and 13 waveforms from black-hole perturbation theory for the (plunge-)merger and ringdown. We quantify the improved accuracy including higher-order modes by computing the faithfulness of the waveform model against the numerical-relativity waveforms used to construct the model. We define the faithfulness as the match maximized over time, phase of arrival, gravitational-wave polarization and sky position of the waveform model, and averaged over binary orientation, gravitational-wave polarization and sky position of the numerical-relativity waveform. When the waveform model contains only the $(2,2)$ mode, we find that the averaged faithfulness to numerical-relativity waveforms containing all modes with $\ell \leq$ 5 ranges from $90\%$ to $99.9\%$ for binaries with total mass $20-200 M_\odot$ (using the Advanced LIGO's design noise curve). By contrast, when the $(2,1),(3,3),(4,4),(5,5)$ modes are also included in the model, the faithfulness improves to $99\%$ for all but four configurations in the numerical-relativity catalog, for which the faithfulness is greater than $98.5\%$. Using our results, we also develop also a (stand-alone) waveform model for the merger-ringdown signal, calibrated to numerical-relativity waveforms, which can be used to measure multiple quasi-normal modes. The multipolar waveform model can be extended to include spin-precession, and will be employed in upcoming observing runs of Advanced LIGO and Virgo. |
2311.07408 | Elena Giorgi | Elena Giorgi | Boundedness and Decay for the Teukolsky System in Kerr-Newman Spacetime
I: The Case $|a|, |Q| \ll M$ | 109 pages | null | null | null | gr-qc math-ph math.AP math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove boundedness and polynomial decay statements for solutions of the
Teukolsky system for electromagnetic-gravitational perturbations of a
Kerr-Newman exterior background, with parameters satisfying $|a|, |Q| \ll M$.
The identification and analysis of the Teukolsky system in Kerr-Newman has long
been problematic due to the long-standing problem of coupling and failure of
separability of the equations. Here, we analyze a system satisfied by novel
gauge-invariant quantities representing gravitational and electromagnetic
radiations for coupled perturbations of a Kerr-Newman black hole. The bounds
are obtained by making use of a generalization of the Chandrasekhar
transformation into a system of coupled generalized Regge-Wheeler equations
derived in previous work. Crucial in our resolution is the use of a combined
energy-momentum tensor for the system which exploits its symmetric structure,
performing an effective decoupling of the perturbations. As for other black
hole solutions, such bounds on the Teukolsky system provide the first step in
proving the non linear stability of the Kerr-Newman metric to gravitational and
electromagnetic perturbations.
| [
{
"created": "Mon, 13 Nov 2023 15:41:53 GMT",
"version": "v1"
}
] | 2023-11-14 | [
[
"Giorgi",
"Elena",
""
]
] | We prove boundedness and polynomial decay statements for solutions of the Teukolsky system for electromagnetic-gravitational perturbations of a Kerr-Newman exterior background, with parameters satisfying $|a|, |Q| \ll M$. The identification and analysis of the Teukolsky system in Kerr-Newman has long been problematic due to the long-standing problem of coupling and failure of separability of the equations. Here, we analyze a system satisfied by novel gauge-invariant quantities representing gravitational and electromagnetic radiations for coupled perturbations of a Kerr-Newman black hole. The bounds are obtained by making use of a generalization of the Chandrasekhar transformation into a system of coupled generalized Regge-Wheeler equations derived in previous work. Crucial in our resolution is the use of a combined energy-momentum tensor for the system which exploits its symmetric structure, performing an effective decoupling of the perturbations. As for other black hole solutions, such bounds on the Teukolsky system provide the first step in proving the non linear stability of the Kerr-Newman metric to gravitational and electromagnetic perturbations. |
gr-qc/0408073 | Valerio Faraoni | Valerio Faraoni | Negative energy and stability in scalar-tensor gravity | 9 pages, latex, to appear in Phys. Rev. D | Phys.Rev. D70 (2004) 081501 | 10.1103/PhysRevD.70.081501 | null | gr-qc | null | Linearized gravitational waves in Brans-Dicke and scalar-tensor theories
carry negative energy. A gauge-invariant analysis shows that the background
Minkowski space is stable at the classical level with respect to linear scalar
and tensor inhomogeneous perturbations.
| [
{
"created": "Fri, 20 Aug 2004 19:58:40 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Faraoni",
"Valerio",
""
]
] | Linearized gravitational waves in Brans-Dicke and scalar-tensor theories carry negative energy. A gauge-invariant analysis shows that the background Minkowski space is stable at the classical level with respect to linear scalar and tensor inhomogeneous perturbations. |
1306.3076 | Andreas Doering | Andreas Doering | Some Remarks on the Logic of Quantum Gravity | 17 pages, no figures | null | null | null | gr-qc math-ph math.MP quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss some conceptual issues that any approach to quantum gravity has to
confront. In particular, it is argued that one has to find a theory that can be
interpreted in a realist manner, because theories with an instrumentalist
interpretation are problematic for several well-known reasons. Since the
Hilbert space formalism almost inevitably forces an instrumentalist
interpretation on us, we suggest that a theory of quantum gravity should not be
based on the Hilbert space formalism. We briefly sketch the topos approach,
which makes use of the internal logic of a topos associated with a quantum
system and comes with a natural (neo-)realist interpretation. Finally, we make
some remarks on the relation between system logic and metalogic.
| [
{
"created": "Thu, 13 Jun 2013 11:05:51 GMT",
"version": "v1"
}
] | 2013-06-14 | [
[
"Doering",
"Andreas",
""
]
] | We discuss some conceptual issues that any approach to quantum gravity has to confront. In particular, it is argued that one has to find a theory that can be interpreted in a realist manner, because theories with an instrumentalist interpretation are problematic for several well-known reasons. Since the Hilbert space formalism almost inevitably forces an instrumentalist interpretation on us, we suggest that a theory of quantum gravity should not be based on the Hilbert space formalism. We briefly sketch the topos approach, which makes use of the internal logic of a topos associated with a quantum system and comes with a natural (neo-)realist interpretation. Finally, we make some remarks on the relation between system logic and metalogic. |
2305.02642 | Xiangdong Zhang | Yunlong Liu and Xiangdong Zhang | Quasinormal modes of the Bardeen black hole with a cloud of strings | 11 pages, 15 figures | Chinese Physics C Vol. 47, No. 12 (2023) 125103 | 10.1088/1674-1137/acf3d5 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We investigate the quasinormal mode and greybody factor of Bardeen black
holes with a string clouds by WKB approximation and verify them by Prony
algorithm. We found that the imaginary part of the quasinormal modes spectra is
always negative and the perturbation does not increase with the time,
indicating that the system is stable under scalar field perturbation. Moreover,
the string parameter $a$ has a dramatically impact on the frequency and decay
rate of the waveforms. In addition, the greybody factor becomes larger when $a$
and $\lambda$ increase while $q$ and $l$ decreases. The parameter $\lambda$ and
$l$ have a big effect on the tails. Especially, when $l=0$, a de Sitter phase
appears at the tail.
| [
{
"created": "Thu, 4 May 2023 08:20:43 GMT",
"version": "v1"
}
] | 2023-11-09 | [
[
"Liu",
"Yunlong",
""
],
[
"Zhang",
"Xiangdong",
""
]
] | We investigate the quasinormal mode and greybody factor of Bardeen black holes with a string clouds by WKB approximation and verify them by Prony algorithm. We found that the imaginary part of the quasinormal modes spectra is always negative and the perturbation does not increase with the time, indicating that the system is stable under scalar field perturbation. Moreover, the string parameter $a$ has a dramatically impact on the frequency and decay rate of the waveforms. In addition, the greybody factor becomes larger when $a$ and $\lambda$ increase while $q$ and $l$ decreases. The parameter $\lambda$ and $l$ have a big effect on the tails. Especially, when $l=0$, a de Sitter phase appears at the tail. |
1005.1491 | Joan Josep Ferrando | Joan Josep Ferrando and Juan Antonio S\'aez | An intrinsic characterization of 2+2 warped spacetimes | 18 pages; submitted to Class. Quantum Grav. | Class.Quant.Grav.27:205023,2010 | 10.1088/0264-9381/27/20/205023 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give several equivalent conditions that characterize the 2+2 warped
spacetimes: imposing the existence of a Killing-Yano tensor $A$ subject to
complementary algebraic restrictions; in terms of the projector $v$ (or of the
canonical 2-form $U$) associated with the 2-planes of the warped product. These
planes are principal planes of the Weyl and/or Ricci tensors and can be
explicitly obtained from them. Therefore, we obtain the necessary and
sufficient (local) conditions for a metric tensor to be a 2+2 warped product.
These conditions exclusively involve explicit concomitants of the Riemann
tensor. We present a similar analysis for the conformally 2+2 product
spacetimes and give an invariant classification of them. The warped products
correspond to two of these invariant classes. The more degenerate class is the
set of product metrics which are also studied from an invariant point of view.
| [
{
"created": "Mon, 10 May 2010 11:10:08 GMT",
"version": "v1"
}
] | 2012-04-19 | [
[
"Ferrando",
"Joan Josep",
""
],
[
"Sáez",
"Juan Antonio",
""
]
] | We give several equivalent conditions that characterize the 2+2 warped spacetimes: imposing the existence of a Killing-Yano tensor $A$ subject to complementary algebraic restrictions; in terms of the projector $v$ (or of the canonical 2-form $U$) associated with the 2-planes of the warped product. These planes are principal planes of the Weyl and/or Ricci tensors and can be explicitly obtained from them. Therefore, we obtain the necessary and sufficient (local) conditions for a metric tensor to be a 2+2 warped product. These conditions exclusively involve explicit concomitants of the Riemann tensor. We present a similar analysis for the conformally 2+2 product spacetimes and give an invariant classification of them. The warped products correspond to two of these invariant classes. The more degenerate class is the set of product metrics which are also studied from an invariant point of view. |
1701.01569 | Igor Nikitin | Igor Nikitin | Static spherically symmetric solutions of Einstein field equations with
radial dark matter | null | 2017 Int. J. Mod. Phys. C 28 1750096 | 10.1142/S0129183117500966 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study a static spherically symmetric problem with a black hole and
radially directed geodesic flows of dark matter. The obtained solutions have
the following properties. At large distances, the gravitational field produces
constant velocities of circular motion, i.e., flat rotation curves. At smaller
distances, the field switches to Newtonian regime, then to Schwarzschild
regime. Deviations from Schwarzschild regime start below the gravitational
radius. The dark matter prevents the creation of event horizon, instead, a
spherical region possessing extremely large redshift is created. The structure
of space-time for the obtained solutions is investigated and the implications
for the models of the galaxies are discussed.
| [
{
"created": "Fri, 6 Jan 2017 08:25:20 GMT",
"version": "v1"
}
] | 2021-02-11 | [
[
"Nikitin",
"Igor",
""
]
] | We study a static spherically symmetric problem with a black hole and radially directed geodesic flows of dark matter. The obtained solutions have the following properties. At large distances, the gravitational field produces constant velocities of circular motion, i.e., flat rotation curves. At smaller distances, the field switches to Newtonian regime, then to Schwarzschild regime. Deviations from Schwarzschild regime start below the gravitational radius. The dark matter prevents the creation of event horizon, instead, a spherical region possessing extremely large redshift is created. The structure of space-time for the obtained solutions is investigated and the implications for the models of the galaxies are discussed. |
1302.4368 | Daniel Siegel | Daniel M. Siegel, Riccardo Ciolfi, Abraham I. Harte, Luciano Rezzolla | Magnetorotational instability in relativistic hypermassive neutron stars | 5 pages, 4 figures. Updated to match published version | Phys. Rev. D 87, 121302(R) (2013) | 10.1103/PhysRevD.87.121302 | null | gr-qc astro-ph.HE astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A differentially rotating hypermassive neutron star (HMNS) is a metastable
object which can be formed in the merger of neutron-star binaries. The eventual
collapse of the HMNS into a black hole is a key element in generating the
physical conditions expected to accompany the launch of a short gamma-ray
burst. We investigate the influence of magnetic fields on HMNSs by performing
three-dimensional simulations in general-relativistic magnetohydrodynamics. In
particular, we provide direct evidence for the occurrence of the
magnetorotational instability (MRI) in HMNS interiors. For the first time in
simulations of these systems, rapidly-growing and spatially-periodic structures
are observed to form with features like those of the channel flows produced by
the MRI in other systems. Moreover, the growth time and wavelength of the
fastest-growing mode are extracted and compared successfully with analytical
predictions. The MRI emerges as an important mechanism to amplify magnetic
fields over the lifetime of the HMNS, whose collapse to a black hole is
accelerated. The evidence provided here that the MRI can actually develop in
HMNSs could have a profound impact on the outcome of the merger of neutron-star
binaries and on its connection to short gamma-ray bursts.
| [
{
"created": "Mon, 18 Feb 2013 17:43:23 GMT",
"version": "v1"
},
{
"created": "Thu, 30 May 2013 09:55:51 GMT",
"version": "v2"
},
{
"created": "Wed, 17 Jul 2013 10:43:54 GMT",
"version": "v3"
}
] | 2013-07-18 | [
[
"Siegel",
"Daniel M.",
""
],
[
"Ciolfi",
"Riccardo",
""
],
[
"Harte",
"Abraham I.",
""
],
[
"Rezzolla",
"Luciano",
""
]
] | A differentially rotating hypermassive neutron star (HMNS) is a metastable object which can be formed in the merger of neutron-star binaries. The eventual collapse of the HMNS into a black hole is a key element in generating the physical conditions expected to accompany the launch of a short gamma-ray burst. We investigate the influence of magnetic fields on HMNSs by performing three-dimensional simulations in general-relativistic magnetohydrodynamics. In particular, we provide direct evidence for the occurrence of the magnetorotational instability (MRI) in HMNS interiors. For the first time in simulations of these systems, rapidly-growing and spatially-periodic structures are observed to form with features like those of the channel flows produced by the MRI in other systems. Moreover, the growth time and wavelength of the fastest-growing mode are extracted and compared successfully with analytical predictions. The MRI emerges as an important mechanism to amplify magnetic fields over the lifetime of the HMNS, whose collapse to a black hole is accelerated. The evidence provided here that the MRI can actually develop in HMNSs could have a profound impact on the outcome of the merger of neutron-star binaries and on its connection to short gamma-ray bursts. |
1511.02936 | Martin Kolo\v{s} | Zden\v{e}k Stuchl\'ik, Martin Kolo\v{s} | Acceleration of charged particles due to chaotic scattering in the
combined black hole gravitational field and asymptotically uniform magnetic
field | 21 pages, 13 figures | null | 10.1140/epjc/s10052-015-3862-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | To test the role of large-scale magnetic fields in accretion processes, we
study dynamics of charged test particles in vicinity of a black hole immersed
into an asymptotically uniform magnetic field. Using the Hamiltonian formalism
of charged particle dynamics, we examine chaotic scattering in the effective
potential related to the black hole gravitational field combined with the
uniform magnetic field. Energy interchange between the translational and
oscillatory modes od the charged particle dynamics provides mechanism for
charged particle acceleration along the magnetic field lines. This energy
transmutation is an attribute of the chaotic charged particle dynamics in the
combined gravitational and magnetic fields only, the black hole rotation is not
necessary for such charged particle acceleration. The chaotic scatter can cause
transition to the motion along the magnetic field lines with small radius of
the Larmor motion or vanishing Larmor radius, when the speed of the particle
translational motion is largest and can be ultra-relativistic. We discuss
consequences of the model of ionization of test particles forming a neutral
accretion disc, or heavy ions following off-equatorial circular orbits, and we
explore the fate of heavy charged test particles after ionization where no kick
of heavy ions is assumed and only switch-on effect of the magnetic field is
relevant. We demonstrate that acceleration and escape of the ionized particles
can be efficient along the Kerr black hole symmetry axis parallel to the
magnetic field lines. We show that strong acceleration of ionized particles to
ultra-relativistic velocities is preferred in the direction close to the
magnetic field lines. Therefore, the process of ionization of Keplerian discs
around Kerr black holes can serve as a model of relativistic jets.
| [
{
"created": "Mon, 9 Nov 2015 23:54:31 GMT",
"version": "v1"
}
] | 2016-02-17 | [
[
"Stuchlík",
"Zdeněk",
""
],
[
"Kološ",
"Martin",
""
]
] | To test the role of large-scale magnetic fields in accretion processes, we study dynamics of charged test particles in vicinity of a black hole immersed into an asymptotically uniform magnetic field. Using the Hamiltonian formalism of charged particle dynamics, we examine chaotic scattering in the effective potential related to the black hole gravitational field combined with the uniform magnetic field. Energy interchange between the translational and oscillatory modes od the charged particle dynamics provides mechanism for charged particle acceleration along the magnetic field lines. This energy transmutation is an attribute of the chaotic charged particle dynamics in the combined gravitational and magnetic fields only, the black hole rotation is not necessary for such charged particle acceleration. The chaotic scatter can cause transition to the motion along the magnetic field lines with small radius of the Larmor motion or vanishing Larmor radius, when the speed of the particle translational motion is largest and can be ultra-relativistic. We discuss consequences of the model of ionization of test particles forming a neutral accretion disc, or heavy ions following off-equatorial circular orbits, and we explore the fate of heavy charged test particles after ionization where no kick of heavy ions is assumed and only switch-on effect of the magnetic field is relevant. We demonstrate that acceleration and escape of the ionized particles can be efficient along the Kerr black hole symmetry axis parallel to the magnetic field lines. We show that strong acceleration of ionized particles to ultra-relativistic velocities is preferred in the direction close to the magnetic field lines. Therefore, the process of ionization of Keplerian discs around Kerr black holes can serve as a model of relativistic jets. |
gr-qc/0404038 | Dmitri Fursaev | Dmitri V. Fursaev | Can One Understand Black Hole Entropy without Knowing Much about Quantum
Gravity? | 38 pages | Phys.Part.Nucl. 36 (2005) 81-99; Fiz.Elem.Chast.Atom.Yadra 36
(2005) 146-182 | null | null | gr-qc hep-th | null | It is a common belief now that the explanation of the microscopic origin of
the Bekenstein-Hawking entropy of black holes should be available in quantum
gravity theory, whatever this theory will finally look like. Calculations of
the entropy of certain black holes in string theory do support this point of
view. In the last few years there also appeared a hope that an understanding of
black hole entropy may be possible even without knowing the details of quantum
gravity. The thermodynamics of black holes is a low energy phenomenon, so only
a few general features of the fundamental theory may be really important. The
aim of this review is to describe some of the proposals in this direction and
the results obtained.
| [
{
"created": "Thu, 8 Apr 2004 12:11:04 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Fursaev",
"Dmitri V.",
""
]
] | It is a common belief now that the explanation of the microscopic origin of the Bekenstein-Hawking entropy of black holes should be available in quantum gravity theory, whatever this theory will finally look like. Calculations of the entropy of certain black holes in string theory do support this point of view. In the last few years there also appeared a hope that an understanding of black hole entropy may be possible even without knowing the details of quantum gravity. The thermodynamics of black holes is a low energy phenomenon, so only a few general features of the fundamental theory may be really important. The aim of this review is to describe some of the proposals in this direction and the results obtained. |
0802.2023 | Antoine Petiteau | Antoine Petiteau (APC), G. Auger (APC), H. Halloin (APC), O. Jeannin
(APC), E. Plagnol (APC), Sophie Pireaux (ARTEMIS), Tania Regimbau (ARTEMIS),
J.-Y. Vinet (ARTEMIS) | LISACode : A scientific simulator of LISA | null | Phys.Rev.D77:023002,2008 | 10.1103/PhysRevD.77.023002 | null | gr-qc astro-ph | null | A new LISA simulator (LISACode) is presented. Its ambition is to achieve a
new degree of sophistication allowing to map, as closely as possible, the
impact of the different sub-systems on the measurements. LISACode is not a
detailed simulator at the engineering level but rather a tool whose purpose is
to bridge the gap between the basic principles of LISA and a future,
sophisticated end-to-end simulator. This is achieved by introducing, in a
realistic manner, most of the ingredients that will influence LISA's
sensitivity as well as the application of TDI combinations. Many user-defined
parameters allow the code to study different configurations of LISA thus
helping to finalize the definition of the detector. Another important use of
LISACode is in generating time series for data analysis developments.
| [
{
"created": "Thu, 14 Feb 2008 14:29:05 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Petiteau",
"Antoine",
"",
"APC"
],
[
"Auger",
"G.",
"",
"APC"
],
[
"Halloin",
"H.",
"",
"APC"
],
[
"Jeannin",
"O.",
"",
"APC"
],
[
"Plagnol",
"E.",
"",
"APC"
],
[
"Pireaux",
"Sophie",
"",
"ARTEMIS"
],
[
"Regimbau",
"Tania",
"",
"ARTEMIS"
],
[
"Vinet",
"J. -Y.",
"",
"ARTEMIS"
]
] | A new LISA simulator (LISACode) is presented. Its ambition is to achieve a new degree of sophistication allowing to map, as closely as possible, the impact of the different sub-systems on the measurements. LISACode is not a detailed simulator at the engineering level but rather a tool whose purpose is to bridge the gap between the basic principles of LISA and a future, sophisticated end-to-end simulator. This is achieved by introducing, in a realistic manner, most of the ingredients that will influence LISA's sensitivity as well as the application of TDI combinations. Many user-defined parameters allow the code to study different configurations of LISA thus helping to finalize the definition of the detector. Another important use of LISACode is in generating time series for data analysis developments. |
0803.0277 | Christophe Le Poncin-Lafitte | Pierre Teyssandier and Christophe Le Poncin-Lafitte | General post-Minkowskian expansion of time transfer functions | 10 pages. Minor modifications. Accepted in Classical and Quantum
Gravity | Class.Quant.Grav.25:145020,2008 | 10.1088/0264-9381/25/14/145020 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Modeling most of the tests of general relativity requires to know the
function relating light travel time to the coordinate time of reception and to
the spatial coordinates of the emitter and the receiver. We call such a
function the reception time transfer function. Of course, an emission time
transfer function may as well be considered. We present here a recursive
procedure enabling to expand each time transfer function into a perturbative
series of ascending powers of the Newtonian gravitational constant $G$ (general
post-Minkowskian expansion). Our method is self-sufficient, in the sense that
neither the integration of null geodesic equations nor the determination of
Synge's world function are necessary. To illustrate the method, the time
transfer function of a three-parameter family of static, spherically symmetric
metrics is derived within the post-linear approximation.
| [
{
"created": "Mon, 3 Mar 2008 16:26:40 GMT",
"version": "v1"
},
{
"created": "Mon, 21 Apr 2008 09:45:32 GMT",
"version": "v2"
},
{
"created": "Mon, 2 Jun 2008 15:42:40 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Teyssandier",
"Pierre",
""
],
[
"Poncin-Lafitte",
"Christophe Le",
""
]
] | Modeling most of the tests of general relativity requires to know the function relating light travel time to the coordinate time of reception and to the spatial coordinates of the emitter and the receiver. We call such a function the reception time transfer function. Of course, an emission time transfer function may as well be considered. We present here a recursive procedure enabling to expand each time transfer function into a perturbative series of ascending powers of the Newtonian gravitational constant $G$ (general post-Minkowskian expansion). Our method is self-sufficient, in the sense that neither the integration of null geodesic equations nor the determination of Synge's world function are necessary. To illustrate the method, the time transfer function of a three-parameter family of static, spherically symmetric metrics is derived within the post-linear approximation. |
1002.0308 | Silke Weinfurtner | Silke Weinfurtner, Thomas P. Sotiriou and Matt Visser | Projectable Horava-Lifshitz gravity in a nutshell | 8 pages, no figures, to appear in the proceedings of First
Mediterranean Conference on Classical and Quantum Gravity Conference (MCCQG),
Kolymbari (Crete, Greece), September 14-18, 2009 | J. Phys.: Conf. Ser. 222, 012054 (2010) | 10.1088/1742-6596/222/1/012054 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Approximately one year ago Horava proposed a power-counting renormalizable
theory of gravity which abandons local Lorentz invariance. The proposal has
been received with growing interest and resulted in various different versions
of Horava-Lifshitz gravity theories, involving a colourful potpourri of new
terminology. In this proceedings contribution we first motivate and briefly
overview the various different approaches, clarifying their differences and
similarities. We then focus on a model referred to as projectable
Horava-Lifshitz gravity and summarize the key results regarding its viability.
| [
{
"created": "Mon, 1 Feb 2010 19:18:14 GMT",
"version": "v1"
}
] | 2011-06-03 | [
[
"Weinfurtner",
"Silke",
""
],
[
"Sotiriou",
"Thomas P.",
""
],
[
"Visser",
"Matt",
""
]
] | Approximately one year ago Horava proposed a power-counting renormalizable theory of gravity which abandons local Lorentz invariance. The proposal has been received with growing interest and resulted in various different versions of Horava-Lifshitz gravity theories, involving a colourful potpourri of new terminology. In this proceedings contribution we first motivate and briefly overview the various different approaches, clarifying their differences and similarities. We then focus on a model referred to as projectable Horava-Lifshitz gravity and summarize the key results regarding its viability. |
0812.1767 | Ricardo Monteiro | Ricardo Monteiro and Jorge E. Santos | Negative modes and the thermodynamics of Reissner-Nordstr\"om black
holes | 24 pages, 1 figure; v2 minor changes to fit published version | Phys. Rev. D 79, 064006 (2009) | 10.1103/PhysRevD.79.064006 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyse the problem of negative modes of the Euclidean section of the
Reissner-Nordstr\"om black hole in four dimensions. We find analytically that a
negative mode disappears when the specific heat at constant charge becomes
positive. The sector of perturbations analysed here is included in the
canonical partition function of the magnetically charged black hole. The result
obeys the usual rule that the partition function is only well-defined when
there is local thermodynamical equilibrium. We point out the difficulty in
quantising Einstein-Maxwell theory, where the so-called conformal factor
problem is considerably more intricate. Our method, inspired by hep-th/0608001,
allows us to decouple the divergent gauge volume and treat the metric
perturbations sector in a gauge-invariant way.
| [
{
"created": "Tue, 9 Dec 2008 18:47:39 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Mar 2009 18:09:48 GMT",
"version": "v2"
}
] | 2009-07-30 | [
[
"Monteiro",
"Ricardo",
""
],
[
"Santos",
"Jorge E.",
""
]
] | We analyse the problem of negative modes of the Euclidean section of the Reissner-Nordstr\"om black hole in four dimensions. We find analytically that a negative mode disappears when the specific heat at constant charge becomes positive. The sector of perturbations analysed here is included in the canonical partition function of the magnetically charged black hole. The result obeys the usual rule that the partition function is only well-defined when there is local thermodynamical equilibrium. We point out the difficulty in quantising Einstein-Maxwell theory, where the so-called conformal factor problem is considerably more intricate. Our method, inspired by hep-th/0608001, allows us to decouple the divergent gauge volume and treat the metric perturbations sector in a gauge-invariant way. |
1806.05195 | Vitor Cardoso | Leor Barack, Vitor Cardoso, Samaya Nissanke, Thomas P. Sotiriou, Abbas
Askar, Krzysztof Belczynski, Gianfranco Bertone, Edi Bon, Diego Blas, Richard
Brito, Tomasz Bulik, Clare Burrage, Christian T. Byrnes, Chiara Caprini,
Masha Chernyakova, Piotr Chrusciel, Monica Colpi, Valeria Ferrari, Daniele
Gaggero, Jonathan Gair, Juan Garcia-Bellido, S. F. Hassan, Lavinia
Heisenberg, Martin Hendry, Ik Siong Heng, Carlos Herdeiro, Tanja Hinderer,
Assaf Horesh, Bradley J. Kavanagh, Bence Kocsis, Michael Kramer, Alexandre Le
Tiec, Chiara Mingarelli, Germano Nardini, Gijs Nelemans, Carlos Palenzuela,
Paolo Pani, Albino Perego, Edward K. Porter, Elena M. Rossi, Patricia
Schmidt, Alberto Sesana, Ulrich Sperhake, Antonio Stamerra, Leo C. Stein,
Nicola Tamanini, Thomas M. Tauris, L. Arturo Urena-Lopez, Frederic Vincent,
Marta Volonteri, Barry Wardell, Norbert Wex, Kent Yagi, Tiziano Abdelsalhin,
Miguel Angel Aloy, Pau Amaro-Seoane, Lorenzo Annulli, Manuel Arca-Sedda,
Ibrahima Bah, Enrico Barausse, Elvis Barakovic, Robert Benkel, Charles L.
Bennett, Laura Bernard, Sebastiano Bernuzzi, Christopher P. L. Berry,
Emanuele Berti, Miguel Bezares, Jose Juan Blanco-Pillado, Jose Luis
Blazquez-Salcedo, Matteo Bonetti, Mateja Boskovic, Zeljka Bosnjak, Katja
Bricman, Bernd Bruegmann, Pedro R. Capelo, Sante Carloni, Pablo Cerda-Duran,
Christos Charmousis, Sylvain Chaty, Aurora Clerici, Andrew Coates, Marta
Colleoni, Lucas G. Collodel, Geoffrey Compere, William Cook, Isabel
Cordero-Carrion, Miguel Correia, Alvaro de la Cruz-Dombriz, Viktor G.
Czinner, Kyriakos Destounis, Kostas Dialektopoulos, Daniela Doneva, Massimo
Dotti, Amelia Drew, Christopher Eckner, James Edholm, Roberto Emparan, Recai
Erdem, Miguel Ferreira, Pedro G. Ferreira, Andrew Finch, Jose A. Font, Nicola
Franchini, Kwinten Fransen, Dmitry Gal'tsov, Apratim Ganguly, Davide Gerosa,
Kostas Glampedakis, Andreja Gomboc, Ariel Goobar, Leonardo Gualtieri, Eduardo
Guendelman, Francesco Haardt, Troels Harmark, Filip Hejda, Thomas Hertog,
Seth Hopper, Sascha Husa, Nada Ihanec, Taishi Ikeda, Amruta Jaodand, Philippe
Jetzer Xisco Jimenez-Forteza, Marc Kamionkowski, David E. Kaplan, Stelios
Kazantzidis, Masashi Kimura, Shiho Kobayashi, Kostas Kokkotas, Julian Krolik,
Jutta Kunz, Claus Lammerzahl, Paul Lasky, Jose P. S. Lemos, Jackson Levi
Said, Stefano Liberati, Jorge Lopes, Raimon Luna, Yin-Zhe Ma, Elisa Maggio,
Marina Martinez Montero, Andrea Maselli, Lucio Mayer, Anupam Mazumdar,
Christopher Messenger, Brice Menard, Masato Minamitsuji, Christopher J.
Moore, David Mota, Sourabh Nampalliwar, Andrea Nerozzi, David Nichols, Emil
Nissimov, Martin Obergaulinger, Niels A. Obers, Roberto Oliveri, George
Pappas, Vedad Pasic, Hiranya Peiris, Tanja Petrushevska, Denis Pollney,
Geraint Pratten, Nemanja Rakic, Istvan Racz, Miren Radia, Fethi M.
Ramazanouglu, Antoni Ramos-Buades, Guilherme Raposo, Roxana Rosca-Mead, Marek
Rogatko, Dorota Rosinska, Stephan Rosswog, Ester Ruiz Morales, Mairi
Sakellariadou, Nicolas Sanchis-Gual, Om Sharan Salafia, Anuradha Samajdar,
Alicia Sintes, Majda Smole, Carlos Sopuerta, Rafael Souza-Lima, Marko
Stalevski, Nikolaos Stergioulas, Chris Stevens, Tomas Tamfal, Alejandro
Torres-Forne, Sergey Tsygankov, Kivanc Unluturk, Rosa Valiante, Maarten van
de Meent, Jose Velhinho, Yosef Verbin, Bert Vercnocke, Daniele Vernieri,
Rodrigo Vicente, Vincenzo Vitagliano, Amanda Weltman, Bernard Whiting, Andrew
Williamson, Helvi Witek, Aneta Wojnar, Kadri Yakut, Haopeng Yan, Stoycho
Yazadjiev, Gabrijela Zaharijas, Miguel Zilhao | Black holes, gravitational waves and fundamental physics: a roadmap | White Paper for the COST action "Gravitational Waves, Black Holes,
and Fundamental Physics", 272 pages, 12 figures; v4: updated references and
author list. Overall improvements and corrections. To appear in Classical and
Quantum Gravity | null | 10.1088/1361-6382/ab0587 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The grand challenges of contemporary fundamental physics---dark matter, dark
energy, vacuum energy, inflation and early universe cosmology, singularities
and the hierarchy problem---all involve gravity as a key component. And of all
gravitational phenomena, black holes stand out in their elegant simplicity,
while harbouring some of the most remarkable predictions of General Relativity:
event horizons, singularities and ergoregions. The hitherto invisible landscape
of the gravitational Universe is being unveiled before our eyes: the historical
direct detection of gravitational waves by the LIGO-Virgo collaboration marks
the dawn of a new era of scientific exploration. Gravitational-wave astronomy
will allow us to test models of black hole formation, growth and evolution, as
well as models of gravitational-wave generation and propagation. It will
provide evidence for event horizons and ergoregions, test the theory of General
Relativity itself, and may reveal the existence of new fundamental fields. The
synthesis of these results has the potential to radically reshape our
understanding of the cosmos and of the laws of Nature. The purpose of this work
is to present a concise, yet comprehensive overview of the state of the art in
the relevant fields of research, summarize important open problems, and lay out
a roadmap for future progress.
| [
{
"created": "Wed, 13 Jun 2018 18:00:06 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Jun 2018 18:00:03 GMT",
"version": "v2"
},
{
"created": "Thu, 26 Jul 2018 20:41:48 GMT",
"version": "v3"
},
{
"created": "Fri, 1 Feb 2019 08:42:45 GMT",
"version": "v4"
}
] | 2019-07-17 | [
[
"Barack",
"Leor",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Nissanke",
"Samaya",
""
],
[
"Sotiriou",
"Thomas P.",
""
],
[
"Askar",
"Abbas",
""
],
[
"Belczynski",
"Krzysztof",
""
],
[
"Bertone",
"Gianfranco",
""
],
[
"Bon",
"Edi",
""
],
[
"Blas",
"Diego",
""
],
[
"Brito",
"Richard",
""
],
[
"Bulik",
"Tomasz",
""
],
[
"Burrage",
"Clare",
""
],
[
"Byrnes",
"Christian T.",
""
],
[
"Caprini",
"Chiara",
""
],
[
"Chernyakova",
"Masha",
""
],
[
"Chrusciel",
"Piotr",
""
],
[
"Colpi",
"Monica",
""
],
[
"Ferrari",
"Valeria",
""
],
[
"Gaggero",
"Daniele",
""
],
[
"Gair",
"Jonathan",
""
],
[
"Garcia-Bellido",
"Juan",
""
],
[
"Hassan",
"S. F.",
""
],
[
"Heisenberg",
"Lavinia",
""
],
[
"Hendry",
"Martin",
""
],
[
"Heng",
"Ik Siong",
""
],
[
"Herdeiro",
"Carlos",
""
],
[
"Hinderer",
"Tanja",
""
],
[
"Horesh",
"Assaf",
""
],
[
"Kavanagh",
"Bradley J.",
""
],
[
"Kocsis",
"Bence",
""
],
[
"Kramer",
"Michael",
""
],
[
"Tiec",
"Alexandre Le",
""
],
[
"Mingarelli",
"Chiara",
""
],
[
"Nardini",
"Germano",
""
],
[
"Nelemans",
"Gijs",
""
],
[
"Palenzuela",
"Carlos",
""
],
[
"Pani",
"Paolo",
""
],
[
"Perego",
"Albino",
""
],
[
"Porter",
"Edward K.",
""
],
[
"Rossi",
"Elena M.",
""
],
[
"Schmidt",
"Patricia",
""
],
[
"Sesana",
"Alberto",
""
],
[
"Sperhake",
"Ulrich",
""
],
[
"Stamerra",
"Antonio",
""
],
[
"Stein",
"Leo C.",
""
],
[
"Tamanini",
"Nicola",
""
],
[
"Tauris",
"Thomas M.",
""
],
[
"Urena-Lopez",
"L. Arturo",
""
],
[
"Vincent",
"Frederic",
""
],
[
"Volonteri",
"Marta",
""
],
[
"Wardell",
"Barry",
""
],
[
"Wex",
"Norbert",
""
],
[
"Yagi",
"Kent",
""
],
[
"Abdelsalhin",
"Tiziano",
""
],
[
"Aloy",
"Miguel Angel",
""
],
[
"Amaro-Seoane",
"Pau",
""
],
[
"Annulli",
"Lorenzo",
""
],
[
"Arca-Sedda",
"Manuel",
""
],
[
"Bah",
"Ibrahima",
""
],
[
"Barausse",
"Enrico",
""
],
[
"Barakovic",
"Elvis",
""
],
[
"Benkel",
"Robert",
""
],
[
"Bennett",
"Charles L.",
""
],
[
"Bernard",
"Laura",
""
],
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Berry",
"Christopher P. L.",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Bezares",
"Miguel",
""
],
[
"Blanco-Pillado",
"Jose Juan",
""
],
[
"Blazquez-Salcedo",
"Jose Luis",
""
],
[
"Bonetti",
"Matteo",
""
],
[
"Boskovic",
"Mateja",
""
],
[
"Bosnjak",
"Zeljka",
""
],
[
"Bricman",
"Katja",
""
],
[
"Bruegmann",
"Bernd",
""
],
[
"Capelo",
"Pedro R.",
""
],
[
"Carloni",
"Sante",
""
],
[
"Cerda-Duran",
"Pablo",
""
],
[
"Charmousis",
"Christos",
""
],
[
"Chaty",
"Sylvain",
""
],
[
"Clerici",
"Aurora",
""
],
[
"Coates",
"Andrew",
""
],
[
"Colleoni",
"Marta",
""
],
[
"Collodel",
"Lucas G.",
""
],
[
"Compere",
"Geoffrey",
""
],
[
"Cook",
"William",
""
],
[
"Cordero-Carrion",
"Isabel",
""
],
[
"Correia",
"Miguel",
""
],
[
"de la Cruz-Dombriz",
"Alvaro",
""
],
[
"Czinner",
"Viktor G.",
""
],
[
"Destounis",
"Kyriakos",
""
],
[
"Dialektopoulos",
"Kostas",
""
],
[
"Doneva",
"Daniela",
""
],
[
"Dotti",
"Massimo",
""
],
[
"Drew",
"Amelia",
""
],
[
"Eckner",
"Christopher",
""
],
[
"Edholm",
"James",
""
],
[
"Emparan",
"Roberto",
""
],
[
"Erdem",
"Recai",
""
],
[
"Ferreira",
"Miguel",
""
],
[
"Ferreira",
"Pedro G.",
""
],
[
"Finch",
"Andrew",
""
],
[
"Font",
"Jose A.",
""
],
[
"Franchini",
"Nicola",
""
],
[
"Fransen",
"Kwinten",
""
],
[
"Gal'tsov",
"Dmitry",
""
],
[
"Ganguly",
"Apratim",
""
],
[
"Gerosa",
"Davide",
""
],
[
"Glampedakis",
"Kostas",
""
],
[
"Gomboc",
"Andreja",
""
],
[
"Goobar",
"Ariel",
""
],
[
"Gualtieri",
"Leonardo",
""
],
[
"Guendelman",
"Eduardo",
""
],
[
"Haardt",
"Francesco",
""
],
[
"Harmark",
"Troels",
""
],
[
"Hejda",
"Filip",
""
],
[
"Hertog",
"Thomas",
""
],
[
"Hopper",
"Seth",
""
],
[
"Husa",
"Sascha",
""
],
[
"Ihanec",
"Nada",
""
],
[
"Ikeda",
"Taishi",
""
],
[
"Jaodand",
"Amruta",
""
],
[
"Jimenez-Forteza",
"Philippe Jetzer Xisco",
""
],
[
"Kamionkowski",
"Marc",
""
],
[
"Kaplan",
"David E.",
""
],
[
"Kazantzidis",
"Stelios",
""
],
[
"Kimura",
"Masashi",
""
],
[
"Kobayashi",
"Shiho",
""
],
[
"Kokkotas",
"Kostas",
""
],
[
"Krolik",
"Julian",
""
],
[
"Kunz",
"Jutta",
""
],
[
"Lammerzahl",
"Claus",
""
],
[
"Lasky",
"Paul",
""
],
[
"Lemos",
"Jose P. S.",
""
],
[
"Said",
"Jackson Levi",
""
],
[
"Liberati",
"Stefano",
""
],
[
"Lopes",
"Jorge",
""
],
[
"Luna",
"Raimon",
""
],
[
"Ma",
"Yin-Zhe",
""
],
[
"Maggio",
"Elisa",
""
],
[
"Montero",
"Marina Martinez",
""
],
[
"Maselli",
"Andrea",
""
],
[
"Mayer",
"Lucio",
""
],
[
"Mazumdar",
"Anupam",
""
],
[
"Messenger",
"Christopher",
""
],
[
"Menard",
"Brice",
""
],
[
"Minamitsuji",
"Masato",
""
],
[
"Moore",
"Christopher J.",
""
],
[
"Mota",
"David",
""
],
[
"Nampalliwar",
"Sourabh",
""
],
[
"Nerozzi",
"Andrea",
""
],
[
"Nichols",
"David",
""
],
[
"Nissimov",
"Emil",
""
],
[
"Obergaulinger",
"Martin",
""
],
[
"Obers",
"Niels A.",
""
],
[
"Oliveri",
"Roberto",
""
],
[
"Pappas",
"George",
""
],
[
"Pasic",
"Vedad",
""
],
[
"Peiris",
"Hiranya",
""
],
[
"Petrushevska",
"Tanja",
""
],
[
"Pollney",
"Denis",
""
],
[
"Pratten",
"Geraint",
""
],
[
"Rakic",
"Nemanja",
""
],
[
"Racz",
"Istvan",
""
],
[
"Radia",
"Miren",
""
],
[
"Ramazanouglu",
"Fethi M.",
""
],
[
"Ramos-Buades",
"Antoni",
""
],
[
"Raposo",
"Guilherme",
""
],
[
"Rosca-Mead",
"Roxana",
""
],
[
"Rogatko",
"Marek",
""
],
[
"Rosinska",
"Dorota",
""
],
[
"Rosswog",
"Stephan",
""
],
[
"Morales",
"Ester Ruiz",
""
],
[
"Sakellariadou",
"Mairi",
""
],
[
"Sanchis-Gual",
"Nicolas",
""
],
[
"Salafia",
"Om Sharan",
""
],
[
"Samajdar",
"Anuradha",
""
],
[
"Sintes",
"Alicia",
""
],
[
"Smole",
"Majda",
""
],
[
"Sopuerta",
"Carlos",
""
],
[
"Souza-Lima",
"Rafael",
""
],
[
"Stalevski",
"Marko",
""
],
[
"Stergioulas",
"Nikolaos",
""
],
[
"Stevens",
"Chris",
""
],
[
"Tamfal",
"Tomas",
""
],
[
"Torres-Forne",
"Alejandro",
""
],
[
"Tsygankov",
"Sergey",
""
],
[
"Unluturk",
"Kivanc",
""
],
[
"Valiante",
"Rosa",
""
],
[
"van de Meent",
"Maarten",
""
],
[
"Velhinho",
"Jose",
""
],
[
"Verbin",
"Yosef",
""
],
[
"Vercnocke",
"Bert",
""
],
[
"Vernieri",
"Daniele",
""
],
[
"Vicente",
"Rodrigo",
""
],
[
"Vitagliano",
"Vincenzo",
""
],
[
"Weltman",
"Amanda",
""
],
[
"Whiting",
"Bernard",
""
],
[
"Williamson",
"Andrew",
""
],
[
"Witek",
"Helvi",
""
],
[
"Wojnar",
"Aneta",
""
],
[
"Yakut",
"Kadri",
""
],
[
"Yan",
"Haopeng",
""
],
[
"Yazadjiev",
"Stoycho",
""
],
[
"Zaharijas",
"Gabrijela",
""
],
[
"Zilhao",
"Miguel",
""
]
] | The grand challenges of contemporary fundamental physics---dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem---all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions. The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature. The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. |
0812.0993 | Jonathan Ziprick | J. Ziprick, G. Kunstatter | Spherically Symmetric Black Hole Formation in Painlev\'e-Gullstrand
Coordinates | 12 pages, 7 figures | Phys.Rev.D79:101503,2009 | 10.1103/PhysRevD.79.101503 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform a numerical study of black hole formation from the spherically
symmetric collapse of a massless scalar field. The calculations are done in
Painlev\'e-Gullstrand (PG) coordinates that extend across apparent horizons and
allow the numerical evolution to proceed until the onset of singularity
formation. We generate spacetime maps of the collapse and illustrate the
evolution of apparent horizons and trapping surfaces for various initial data.
We also study the critical behaviour and find the expected Choptuik scaling
with universal values for the critical exponent and echoing period consistent
with the accepted values of $\gamma=0.374$ and $\Delta = 3.44$, respectively.
The subcritical curvature scaling exhibits the expected oscillatory behaviour
but the form of the periodic oscillations in the supercritical mass scaling
relation, while universal with respect to initial PG data, is non-standard: it
is non-sinusoidal with large amplitude cusps.
| [
{
"created": "Thu, 4 Dec 2008 17:47:22 GMT",
"version": "v1"
}
] | 2009-07-30 | [
[
"Ziprick",
"J.",
""
],
[
"Kunstatter",
"G.",
""
]
] | We perform a numerical study of black hole formation from the spherically symmetric collapse of a massless scalar field. The calculations are done in Painlev\'e-Gullstrand (PG) coordinates that extend across apparent horizons and allow the numerical evolution to proceed until the onset of singularity formation. We generate spacetime maps of the collapse and illustrate the evolution of apparent horizons and trapping surfaces for various initial data. We also study the critical behaviour and find the expected Choptuik scaling with universal values for the critical exponent and echoing period consistent with the accepted values of $\gamma=0.374$ and $\Delta = 3.44$, respectively. The subcritical curvature scaling exhibits the expected oscillatory behaviour but the form of the periodic oscillations in the supercritical mass scaling relation, while universal with respect to initial PG data, is non-standard: it is non-sinusoidal with large amplitude cusps. |
gr-qc/0107031 | Herbert W. Hamber | H.W. Hamber and G. Kagel | Exact Bianchi Identity in Regge Gravity | LaTeX, 45 pages, 6 figures, revised & expanded, references added | Class.Quant.Grav. 21 (2004) 5915-5948 | 10.1088/0264-9381/21/24/013 | null | gr-qc | null | In the continuum the Bianchi identity implies a relationship between
different components of the curvature tensor, thus ensuring the internal
consistency of the gravitational field equations. In this paper an exact form
for the Bianchi identity in Regge's discrete formulation of gravity is derived,
by considering appropriate products of rotation matrices constructed around
null-homotopic paths. It implies an algebraic relationship between deficit
angles belonging to neighboring hinges. As in the continuum, the derived
identity is valid for arbitrarily curved manifolds, without a restriction to
the weak field, small curvature limit, but is in general not linear in the
curvatures.
| [
{
"created": "Tue, 10 Jul 2001 05:47:18 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Oct 2004 20:16:50 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Hamber",
"H. W.",
""
],
[
"Kagel",
"G.",
""
]
] | In the continuum the Bianchi identity implies a relationship between different components of the curvature tensor, thus ensuring the internal consistency of the gravitational field equations. In this paper an exact form for the Bianchi identity in Regge's discrete formulation of gravity is derived, by considering appropriate products of rotation matrices constructed around null-homotopic paths. It implies an algebraic relationship between deficit angles belonging to neighboring hinges. As in the continuum, the derived identity is valid for arbitrarily curved manifolds, without a restriction to the weak field, small curvature limit, but is in general not linear in the curvatures. |
1609.05893 | Alireza Talebian Ashkezari | Alireza Talebian-Ashkezari, Nahid Ahmadi, Ali Akbar Abolhasani | \bf $\delta M$ Formalism: A New Approach to Cosmological Perturbation
Theory in Anisotropic Inflation | 35 pages, 2 figures | JCAP 03(2018)001 | 10.1088/1475-7516/2018/03/001 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the evolution of the metric perturbations in a Bianchi background in
the long-wavelength limit. By applying the gradient expansion to the equations
of motion we exhibit a generalized "Separate Universe" approach to the
cosmological perturbation theory. Having found this consistent separate
universe picture, we introduce the $\delta M $ formalism for calculating the
evolution of the linear tensor perturbations in anisotropic inflation models in
{\it almost} the same way that the so-called $\delta N$ formula is applied to
the super-horizon dynamics of the curvature perturbations. Similar to her twin
formula, $\delta N$, this new method can substantially reduce the amount of
calculations related to the evolution of tensor modes. However, it is not as
general as $\delta N$, it is a "perturbative" formula and solves the shear only
to linear order. In other words, it is restricted to weak shear limit.
| [
{
"created": "Mon, 19 Sep 2016 13:25:39 GMT",
"version": "v1"
},
{
"created": "Sat, 10 Mar 2018 05:30:54 GMT",
"version": "v2"
}
] | 2018-03-13 | [
[
"Talebian-Ashkezari",
"Alireza",
""
],
[
"Ahmadi",
"Nahid",
""
],
[
"Abolhasani",
"Ali Akbar",
""
]
] | We study the evolution of the metric perturbations in a Bianchi background in the long-wavelength limit. By applying the gradient expansion to the equations of motion we exhibit a generalized "Separate Universe" approach to the cosmological perturbation theory. Having found this consistent separate universe picture, we introduce the $\delta M $ formalism for calculating the evolution of the linear tensor perturbations in anisotropic inflation models in {\it almost} the same way that the so-called $\delta N$ formula is applied to the super-horizon dynamics of the curvature perturbations. Similar to her twin formula, $\delta N$, this new method can substantially reduce the amount of calculations related to the evolution of tensor modes. However, it is not as general as $\delta N$, it is a "perturbative" formula and solves the shear only to linear order. In other words, it is restricted to weak shear limit. |
0904.4435 | Francesco Cianfrani dr | F. Cianfrani, G. Montani | Matter in Loop Quantum Gravity without time gauge: a non-minimally
coupled scalar field | 6 pages | Phys. Rev. D 80, (2009) 084045 | 10.1103/PhysRevD.80.084045 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the phase space of gravity non-minimally coupled to a scalar field
in a generic local Lorentz frame. We reduce the set of constraints to a
first-class one by fixing a specific hypersurfaces in the phase space. The main
issue of our analysis is to extend the features of the vacuum case to the
presence of scalar matter by recovering the emergence of an SU(2) gauge
structure and the non-dynamical role of boost variables. Within this scheme,
the super-momentum and the super-Hamiltonian are those ones associated with a
scalar field minimally coupled to the metric in the Einstein frame. Hence, the
kinematical Hilbert space is defined as in canonical Loop Quantum Gravity with
a scalar field, but the differences in the area spectrum are outlined to be the
same as in the time-gauge approach.
| [
{
"created": "Tue, 28 Apr 2009 16:07:08 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Nov 2009 17:32:36 GMT",
"version": "v2"
}
] | 2013-05-29 | [
[
"Cianfrani",
"F.",
""
],
[
"Montani",
"G.",
""
]
] | We analyze the phase space of gravity non-minimally coupled to a scalar field in a generic local Lorentz frame. We reduce the set of constraints to a first-class one by fixing a specific hypersurfaces in the phase space. The main issue of our analysis is to extend the features of the vacuum case to the presence of scalar matter by recovering the emergence of an SU(2) gauge structure and the non-dynamical role of boost variables. Within this scheme, the super-momentum and the super-Hamiltonian are those ones associated with a scalar field minimally coupled to the metric in the Einstein frame. Hence, the kinematical Hilbert space is defined as in canonical Loop Quantum Gravity with a scalar field, but the differences in the area spectrum are outlined to be the same as in the time-gauge approach. |
gr-qc/0108008 | Brien C. Nolan | Filipe C Mena, Brien C Nolan | Non-radial null geodesics in spherical dust collapse | 26 pages, 1 figure | Class.Quant.Grav. 18 (2001) 4531-4548 | 10.1088/0264-9381/18/21/310 | null | gr-qc | null | The issue of the local visibility of the shell-focussing singularity in
marginally bound spherical dust collapse is considered from the point of view
of the existence of future-directed null geodesics with angular momentum which
emanate from the singularity. The initial data (i.e. the initial density
profile) at the onset of collapse is taken to be of class $C^3$. Simple
necessary and sufficient conditions for the existence of a naked singularity
are derived in terms of the data. It is shown that there exist future-directed
non-radial null geodesics emanating from the singularity if and only if there
exist future-directed radial null geodesics emanating from the singularity.
This result can be interpreted as indicating the robustness of previous results
on radial geodesics, with respect to the presence of angular momentum.
| [
{
"created": "Thu, 2 Aug 2001 17:53:28 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Mena",
"Filipe C",
""
],
[
"Nolan",
"Brien C",
""
]
] | The issue of the local visibility of the shell-focussing singularity in marginally bound spherical dust collapse is considered from the point of view of the existence of future-directed null geodesics with angular momentum which emanate from the singularity. The initial data (i.e. the initial density profile) at the onset of collapse is taken to be of class $C^3$. Simple necessary and sufficient conditions for the existence of a naked singularity are derived in terms of the data. It is shown that there exist future-directed non-radial null geodesics emanating from the singularity if and only if there exist future-directed radial null geodesics emanating from the singularity. This result can be interpreted as indicating the robustness of previous results on radial geodesics, with respect to the presence of angular momentum. |
1604.01157 | Aymen Hamid Mr | Aymen I. M. Hamid, Rituparno Goswami and Sunil D. Maharaj | Notes on Cosmic Censorship Conjecture revisited: Covariantly | 6 pages, Conference proceeding for MG14, submitted to MG14 2015,
based on arXiv:1402.4355 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we study the dynamics of the trapped region using a frame
independent semi-tetrad covariant formalism for general Locally Rotationally
Symmetric (LRS) class II spacetimes. We covariantly prove some important
geometrical results for the apparent horizon, and state the necessary and
sufficient conditions for a singularity to be locally naked. These conditions
bring out, for the first time in a quantitative and transparent manner, the
importance of the Weyl curvature in deforming and delaying the trapped region
during continual gravitational collapse, making the central singularity locally
visible.
| [
{
"created": "Tue, 5 Apr 2016 07:15:27 GMT",
"version": "v1"
}
] | 2016-04-06 | [
[
"Hamid",
"Aymen I. M.",
""
],
[
"Goswami",
"Rituparno",
""
],
[
"Maharaj",
"Sunil D.",
""
]
] | In this paper we study the dynamics of the trapped region using a frame independent semi-tetrad covariant formalism for general Locally Rotationally Symmetric (LRS) class II spacetimes. We covariantly prove some important geometrical results for the apparent horizon, and state the necessary and sufficient conditions for a singularity to be locally naked. These conditions bring out, for the first time in a quantitative and transparent manner, the importance of the Weyl curvature in deforming and delaying the trapped region during continual gravitational collapse, making the central singularity locally visible. |
gr-qc/9710029 | Maartens R. Staf | L Chimento, A Jakubi, V Mendez and R Maartens | Cosmological solutions with nonlinear bulk viscosity | 16 pages Latex (IOP style); to appear Class. Quantum Grav | Class.Quant.Grav. 14 (1997) 3363-3375 | 10.1088/0264-9381/14/12/019 | null | gr-qc | null | A recently proposed nonlinear transport equation is used to model bulk
viscous cosmologies that may be far from equilibrium, as happens during viscous
fluid inflation or during reheating. The asymptotic stability of the de Sitter
and Friedmann solutions is investigated. The former is stable for bulk
viscosity index $q<1$ and the latter for $q>1$. New solutions are obtained in
the weakly nonlinear regime for $q=1$. These solutions are singular and some of
them represent a late-time inflationary era.
| [
{
"created": "Mon, 6 Oct 1997 06:51:49 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Chimento",
"L",
""
],
[
"Jakubi",
"A",
""
],
[
"Mendez",
"V",
""
],
[
"Maartens",
"R",
""
]
] | A recently proposed nonlinear transport equation is used to model bulk viscous cosmologies that may be far from equilibrium, as happens during viscous fluid inflation or during reheating. The asymptotic stability of the de Sitter and Friedmann solutions is investigated. The former is stable for bulk viscosity index $q<1$ and the latter for $q>1$. New solutions are obtained in the weakly nonlinear regime for $q=1$. These solutions are singular and some of them represent a late-time inflationary era. |
2405.01594 | Gaurav Gadbail | Gaurav N. Gadbail, P.K. Sahoo | Modified $f(Q)$ gravity models and their cosmological consequences | Chinese Journal of Physics published version | Chinese Journal of Physics 89 (2024) 1754-1762 | 10.1016/j.cjph.2024.04.037 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this work, we consider three different $f(Q)$ models, such as power-law,
exponential, and logarithmic, to study which model better mimics $\Lambda$CDM
evolution theoretically. Henceforth, we determine solutions to the $f(Q)$
gravity field equations in the isotropic and homogeneous universe. Since all
the models contain two model parameters, we reduce the degrees of freedom using
the first Friedman equation at the present time. Further, we check the behavior
of cosmological parameters using the obtained solution to the field equations
and compare it with the $\Lambda$CDM model. As a result, the power-law model
shows a good match with $\Lambda$CDM model for $\lambda=-1$ and $\lambda=-2$,
while the exponential model behaves well for the range $5\le \beta<11$, and the
logarithmic model matches for $3.8<\gamma<4.4$.
| [
{
"created": "Tue, 30 Apr 2024 09:42:03 GMT",
"version": "v1"
}
] | 2024-05-10 | [
[
"Gadbail",
"Gaurav N.",
""
],
[
"Sahoo",
"P. K.",
""
]
] | In this work, we consider three different $f(Q)$ models, such as power-law, exponential, and logarithmic, to study which model better mimics $\Lambda$CDM evolution theoretically. Henceforth, we determine solutions to the $f(Q)$ gravity field equations in the isotropic and homogeneous universe. Since all the models contain two model parameters, we reduce the degrees of freedom using the first Friedman equation at the present time. Further, we check the behavior of cosmological parameters using the obtained solution to the field equations and compare it with the $\Lambda$CDM model. As a result, the power-law model shows a good match with $\Lambda$CDM model for $\lambda=-1$ and $\lambda=-2$, while the exponential model behaves well for the range $5\le \beta<11$, and the logarithmic model matches for $3.8<\gamma<4.4$. |
1204.0774 | Hoavo Hova | Hoavo Hova | A Dark Energy Model in Lyra Manifold | 15 pages, 2 figures, LaTeX file | Journal of Geometry and Physics 64 (2013) 146-154 | 10.1016/j.geomphys.2012.08.004 | null | gr-qc | http://creativecommons.org/licenses/publicdomain/ | We consider, in normal-gauge Lyra's geometry, evolution of a homogeneous
isotropic universe in a gravitational model involving only the standard matter
in interaction with a displacement vector field $\phi_{\mu}$. Considering both
constant and time-dependent displacement vector field we show that the observed
cosmic acceleration could be explained without considering an alien energy
component with a negative pressure.
| [
{
"created": "Sun, 1 Apr 2012 05:52:23 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Apr 2012 08:54:34 GMT",
"version": "v2"
}
] | 2012-12-18 | [
[
"Hova",
"Hoavo",
""
]
] | We consider, in normal-gauge Lyra's geometry, evolution of a homogeneous isotropic universe in a gravitational model involving only the standard matter in interaction with a displacement vector field $\phi_{\mu}$. Considering both constant and time-dependent displacement vector field we show that the observed cosmic acceleration could be explained without considering an alien energy component with a negative pressure. |
1507.01580 | Cedric Troessaert | Cedric Troessaert | Poisson Structure of the Boundary Gravitons in 3D Gravity with Negative
$\Lambda$ | null | null | 10.1088/0264-9381/32/23/235019 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use the hamiltonian formalism to study the asymptotic structure of 3
dimensional gravity with a negative cosmological constant. We start by defining
very general fall-off conditions for the canonical variables and study the
implied poisson structure of the boundary gravitons. From the allowed
differentiable gauge transformations, we can extract all the possible boundary
conditions on the lagrange multipliers and the associated boundary
hamiltonians. In the last section, we use this general framework to describe
some of the previoussly known boundary conditions.
| [
{
"created": "Mon, 6 Jul 2015 19:52:15 GMT",
"version": "v1"
}
] | 2015-12-09 | [
[
"Troessaert",
"Cedric",
""
]
] | We use the hamiltonian formalism to study the asymptotic structure of 3 dimensional gravity with a negative cosmological constant. We start by defining very general fall-off conditions for the canonical variables and study the implied poisson structure of the boundary gravitons. From the allowed differentiable gauge transformations, we can extract all the possible boundary conditions on the lagrange multipliers and the associated boundary hamiltonians. In the last section, we use this general framework to describe some of the previoussly known boundary conditions. |
0901.2741 | James Lindesay | James Lindesay | Global Structure of a Multi-Fluid Cosmology | 18 pages, 6 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Fluid cosmologies are consistent with the generally accepted observational
evidence during intermediate and late times, and they need not have singular
behavior in primordial times. A general form for fluid cosmology consistent
with Einstein's equation is demonstrated, and a dynamic metric that
incorporates fluid scale is developed. The large scale causal structure of a
multi-fluid cosmology exemplary of standard cosmology is then examined. This is
done through developing coupled rate equations for radiation, dust, and dark
components. The beginning of the dissolution of the primordial fluid into the
other components is singularity-free, since the fluid provides a non-vanishing
scale for the cosmology. Penrose diagrams are developed for cosmologies both
with and without a final state dark energy density.
| [
{
"created": "Sun, 18 Jan 2009 22:17:48 GMT",
"version": "v1"
}
] | 2009-01-20 | [
[
"Lindesay",
"James",
""
]
] | Fluid cosmologies are consistent with the generally accepted observational evidence during intermediate and late times, and they need not have singular behavior in primordial times. A general form for fluid cosmology consistent with Einstein's equation is demonstrated, and a dynamic metric that incorporates fluid scale is developed. The large scale causal structure of a multi-fluid cosmology exemplary of standard cosmology is then examined. This is done through developing coupled rate equations for radiation, dust, and dark components. The beginning of the dissolution of the primordial fluid into the other components is singularity-free, since the fluid provides a non-vanishing scale for the cosmology. Penrose diagrams are developed for cosmologies both with and without a final state dark energy density. |
gr-qc/0607003 | Carlos Augusto Romero Filho | J. B. Formiga and C. Romero | On the spectral shift and the time delay of light in a Rindler
accelerated frame | 12 pages, 3 figures | Int.J.Mod.Phys.D16:699-710,2007 | 10.1142/S021827180700984X | null | gr-qc | null | We discuss two effects predicted by the general theory of relativity in the
context of Rindler accelerated observers: the gravitational spectral shift and
the time delay of light. We show that these effects also appear in a Rindler
frame in the absence of gravitational field, in accordance with the Einstein's
equivalence principle.
| [
{
"created": "Sun, 2 Jul 2006 14:29:46 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Formiga",
"J. B.",
""
],
[
"Romero",
"C.",
""
]
] | We discuss two effects predicted by the general theory of relativity in the context of Rindler accelerated observers: the gravitational spectral shift and the time delay of light. We show that these effects also appear in a Rindler frame in the absence of gravitational field, in accordance with the Einstein's equivalence principle. |
2001.01591 | Mubasher Jamil | Seyed Hossein Hendi, Azadeh Nemati, Kai Lin, Mubasher Jamil | Instability and phase transitions of a rotating black hole in the
presence of perfect fluid dark matter | 13 pages, 14 figures, version accepted for publication in Eur. Phys.
J. C | Eur. Phys. J. C (2020) 80:296 | 10.1140/epjc/s10052-020-7829-6 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the thermodynamic features of a rotating black hole
surrounded by perfect fluid dark matter. We analyze the critical behavior of
the black hole by considering the known relationship between pressure and
cosmological constant. We show that the black hole admits a first order phase
transition and, both rotation and perfect fluid dark matter parameters have a
significant impact on the critical quantities. We also introduce a new ad hoc
pressure related to the perfect fluid dark matter and find a first order van
der Waals like phase transition. In addition, using the sixth order WKB method,
we investigate the massless scalar quasinormal modes (QNMs) for the static
spherically symmetric black hole surrounded by dark matter. Using the finite
difference scheme, the dynamical evolution of the QNMs is also discussed for
different values of angular momentum and overtone parameters.
| [
{
"created": "Thu, 2 Jan 2020 06:28:46 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Mar 2020 04:50:01 GMT",
"version": "v2"
}
] | 2020-04-03 | [
[
"Hendi",
"Seyed Hossein",
""
],
[
"Nemati",
"Azadeh",
""
],
[
"Lin",
"Kai",
""
],
[
"Jamil",
"Mubasher",
""
]
] | In this paper, we study the thermodynamic features of a rotating black hole surrounded by perfect fluid dark matter. We analyze the critical behavior of the black hole by considering the known relationship between pressure and cosmological constant. We show that the black hole admits a first order phase transition and, both rotation and perfect fluid dark matter parameters have a significant impact on the critical quantities. We also introduce a new ad hoc pressure related to the perfect fluid dark matter and find a first order van der Waals like phase transition. In addition, using the sixth order WKB method, we investigate the massless scalar quasinormal modes (QNMs) for the static spherically symmetric black hole surrounded by dark matter. Using the finite difference scheme, the dynamical evolution of the QNMs is also discussed for different values of angular momentum and overtone parameters. |
2301.01551 | Songbai Chen | Xin Qin, Songbai Chen, Zelin Zhang, Jiliang Jing | Polarized image of a rotating black hole surrounded by a cold dark
matter halo | 17 pages, 10 figures, Accepted for publication in EPJC | Eur. Phys. J. C 83, 159 (2023) | 10.1140/epjc/s10052-023-11300-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have studied the polarized image of an equatorial emitting ring around a
rotating black hole surrounded by a cold dark matter (CDM) halo. Results show
that the CDM halo density has the similar effects of the halo's characteristic
radius on the polarized image for the black hole. The effects of the CDM halo
on the polarized image depend on the magnetic field configuration, the fluid
velocity and the observed inclination. With the increase of the CDM halo
parameters, the observed polarization intensity decreases when the magnetic
field lies in equatorial plane, but in the case where the magnetic field is
perpendicular to the equatorial plane, the change of the observed polarization
intensity with CDM halo also depends on the position of the emitting point in
the ring. The change of the electric vector position angle (EVPA) with the CDM
halo becomes more complicated. Our results also show that the influence of the
CDM halo on the polarized image is generally small, which are consistent with
the effects of dark matter halo on black hole shadows. These results could help
to further understand dark matter from black hole images.
| [
{
"created": "Wed, 4 Jan 2023 11:42:45 GMT",
"version": "v1"
},
{
"created": "Sun, 19 Feb 2023 03:11:05 GMT",
"version": "v2"
}
] | 2023-03-22 | [
[
"Qin",
"Xin",
""
],
[
"Chen",
"Songbai",
""
],
[
"Zhang",
"Zelin",
""
],
[
"Jing",
"Jiliang",
""
]
] | We have studied the polarized image of an equatorial emitting ring around a rotating black hole surrounded by a cold dark matter (CDM) halo. Results show that the CDM halo density has the similar effects of the halo's characteristic radius on the polarized image for the black hole. The effects of the CDM halo on the polarized image depend on the magnetic field configuration, the fluid velocity and the observed inclination. With the increase of the CDM halo parameters, the observed polarization intensity decreases when the magnetic field lies in equatorial plane, but in the case where the magnetic field is perpendicular to the equatorial plane, the change of the observed polarization intensity with CDM halo also depends on the position of the emitting point in the ring. The change of the electric vector position angle (EVPA) with the CDM halo becomes more complicated. Our results also show that the influence of the CDM halo on the polarized image is generally small, which are consistent with the effects of dark matter halo on black hole shadows. These results could help to further understand dark matter from black hole images. |
gr-qc/9509041 | Henri Waelbroeck | A. Criscuolo, H. Quevedo and H. Waelbroeck (Instituto de Ciencias
Nucleares, UNAM, Mexico) | Quantization of 2+1 Gravity on the Torus | TeX file, 11 pages, proceedings of the CAP 95 meeting in Quebec | null | null | null | gr-qc | null | We use the polygon representation of 2+1--dimensional gravity to explicitly
carry out the canonical quantization of a universe with the topology of a
torus. The mapping-class-invariant wave function for a quantum ''big bounce'',
is reminiscent of the interference patterns of linear gratings. We consider the
``problem of time'' of quantum gravity: for one choice of internal time the
universe recovers a semiclassical interpretation after the bounce, with a wave
packet centered at a single geometry; for another choice of internal time, the
quantum solutions involve interference between macroscopically distinct
universes.
| [
{
"created": "Fri, 22 Sep 1995 17:37:20 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Criscuolo",
"A.",
"",
"Instituto de Ciencias\n Nucleares, UNAM, Mexico"
],
[
"Quevedo",
"H.",
"",
"Instituto de Ciencias\n Nucleares, UNAM, Mexico"
],
[
"Waelbroeck",
"H.",
"",
"Instituto de Ciencias\n Nucleares, UNAM, Mexico"
]
] | We use the polygon representation of 2+1--dimensional gravity to explicitly carry out the canonical quantization of a universe with the topology of a torus. The mapping-class-invariant wave function for a quantum ''big bounce'', is reminiscent of the interference patterns of linear gratings. We consider the ``problem of time'' of quantum gravity: for one choice of internal time the universe recovers a semiclassical interpretation after the bounce, with a wave packet centered at a single geometry; for another choice of internal time, the quantum solutions involve interference between macroscopically distinct universes. |
gr-qc/0603107 | Gabriele Gionti S.J. | Gabriele Gionti S.J | From Local Regge Calculus towards Spin Foam Formalism? | 14 pages, 1 figures, proceeding of the Albert Einstein's
International Conference 18-22 July 2005 | null | null | null | gr-qc hep-lat hep-th math-ph math.MP | null | We introduce the basic elements of SO(n)-local theory of Regge Calculus. A
first order formalism, in the sense of Palatini, is defined on the metric-dual
Voronoi complex of a simplicial complex. The Quantum Measure exhibits an
expansion, in four dimensions, in characters of irreducible representation of
SO(4) which has close resemblance and differences as well with the Spin Foam
Formalism. The coupling with fermionic matter is easily introduced which could
have consequences for the Spin Foam Formalism and Loop Quantum Gravity.
| [
{
"created": "Tue, 28 Mar 2006 19:39:20 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"J",
"Gabriele Gionti S.",
""
]
] | We introduce the basic elements of SO(n)-local theory of Regge Calculus. A first order formalism, in the sense of Palatini, is defined on the metric-dual Voronoi complex of a simplicial complex. The Quantum Measure exhibits an expansion, in four dimensions, in characters of irreducible representation of SO(4) which has close resemblance and differences as well with the Spin Foam Formalism. The coupling with fermionic matter is easily introduced which could have consequences for the Spin Foam Formalism and Loop Quantum Gravity. |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.