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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/0010028 | Mohammad Reza Setare | M. R. Setare and R. Mansouri | Casimir Effect for Spherical Shell in de Sitter Space | 9 pages, submitted to Class. Quantum Grav | Class.Quant.Grav. 18 (2001) 2331 | 10.1088/0264-9381/18/12/308 | null | gr-qc | null | The Casimir stress on a spherical shell in de Sitter background for massless
scalar field satisfying Dirichlet boundary conditions on the shell is
calculated. The metric is written in conformally flat form. Although the metric
is time dependent no particles are created. The Casimir stress is calculated
for inside and outside of the shell with different backgrounds corresponding to
different cosmological constants. The detail dynamics of the bubble depends on
different parameter of the model. Specifically, bubbles with true vacuum inside
expand if the difference in the vacuum energies is small, otherwise they
collapse.
| [
{
"created": "Sun, 8 Oct 2000 11:00:40 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Oct 2000 14:06:17 GMT",
"version": "v2"
},
{
"created": "Sun, 17 Dec 2000 10:01:17 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Setare",
"M. R.",
""
],
[
"Mansouri",
"R.",
""
]
] | The Casimir stress on a spherical shell in de Sitter background for massless scalar field satisfying Dirichlet boundary conditions on the shell is calculated. The metric is written in conformally flat form. Although the metric is time dependent no particles are created. The Casimir stress is calculated for inside and outside of the shell with different backgrounds corresponding to different cosmological constants. The detail dynamics of the bubble depends on different parameter of the model. Specifically, bubbles with true vacuum inside expand if the difference in the vacuum energies is small, otherwise they collapse. |
1405.3513 | Shamaila Rani | M. Sharif and Shamaila Rani | Nonlinear Electrodynamics in $f(T)$ Gravity and Generalized Second Law
of Thermodynamics | 21 pages, 10 figures | Astrophys. Space Sci. 346(2013)573 | 10.1007/s10509-013-1480-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the nonlinear electrodynamics in the framework of
$f(T)$ gravity for FRW universe along with dust matter, magnetic and torsion
contributions. We evaluate the equation of state and deceleration parameters to
explore the accelerated expansion of the universe. The validity of generalized
second law of thermodynamics for Hubble and event horizons is also investigated
in this scenario. For this purpose, we assume pole-like and power-law forms of
scale factor and construct $f(T)$ models. The graphical behavior of the
cosmological parameters versus smaller values of redshift $z$ represent the
accelerated expansion of the universe. It turns out that the generalized second
law of thermodynamics holds for all values of $z$ with event horizon for
power-law scale factor whereas it holds in a specific range of $z$ with Hubble
horizon for power-law and both horizons in pole-like scale factors.
| [
{
"created": "Tue, 3 Dec 2013 15:05:23 GMT",
"version": "v1"
}
] | 2015-06-19 | [
[
"Sharif",
"M.",
""
],
[
"Rani",
"Shamaila",
""
]
] | In this paper, we study the nonlinear electrodynamics in the framework of $f(T)$ gravity for FRW universe along with dust matter, magnetic and torsion contributions. We evaluate the equation of state and deceleration parameters to explore the accelerated expansion of the universe. The validity of generalized second law of thermodynamics for Hubble and event horizons is also investigated in this scenario. For this purpose, we assume pole-like and power-law forms of scale factor and construct $f(T)$ models. The graphical behavior of the cosmological parameters versus smaller values of redshift $z$ represent the accelerated expansion of the universe. It turns out that the generalized second law of thermodynamics holds for all values of $z$ with event horizon for power-law scale factor whereas it holds in a specific range of $z$ with Hubble horizon for power-law and both horizons in pole-like scale factors. |
0804.3274 | Ian Harry | I.W. Harry, S. Fairhurst, B.S. Sathyaprakash | A hierarchical search for gravitational waves from supermassive black
hole binary mergers | 11 pages, 2 figures, for GWDAW-12 proceedings edition of CQG | Class.Quant.Grav.25:184027,2008 | 10.1088/0264-9381/25/18/184027 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a method to search for gravitational waves from coalescing
supermassive binary black holes in LISA data. The search utilizes the
$\mathcal{F}$-statistic to maximize over, and determine the values of, the
extrinsic parameters of the binary system. The intrinsic parameters are
searched over hierarchically using stochastically generated multi-dimensional
template banks to recover the masses and sky locations of the binary. We
present the results of this method applied to the mock LISA data Challenge 1B
data set.
| [
{
"created": "Mon, 21 Apr 2008 11:38:25 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Oct 2008 11:48:41 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Harry",
"I. W.",
""
],
[
"Fairhurst",
"S.",
""
],
[
"Sathyaprakash",
"B. S.",
""
]
] | We present a method to search for gravitational waves from coalescing supermassive binary black holes in LISA data. The search utilizes the $\mathcal{F}$-statistic to maximize over, and determine the values of, the extrinsic parameters of the binary system. The intrinsic parameters are searched over hierarchically using stochastically generated multi-dimensional template banks to recover the masses and sky locations of the binary. We present the results of this method applied to the mock LISA data Challenge 1B data set. |
1407.0938 | Nabil Youssef L | Nabil L. Youssef, Amr M. Sid-Ahmed and Ebtsam H. Taha | Gravity theory in SAP-geometry | 14 pages, References added and a reference updated, minor corrections | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The aim of the present paper is to construct a field theory in the context of
absolute parallelism (Teleparallel) geometry under the assumption that the
canonical connection is semi-symmetric. The field equations are formulated
using a suitable Lagrangian first proposed by Mikhail and Wanas. The
mathematical and physical consequences arising from the obtained field
equations are investigated.
| [
{
"created": "Thu, 3 Jul 2014 14:56:25 GMT",
"version": "v1"
},
{
"created": "Mon, 21 Jul 2014 15:53:53 GMT",
"version": "v2"
}
] | 2014-07-22 | [
[
"Youssef",
"Nabil L.",
""
],
[
"Sid-Ahmed",
"Amr M.",
""
],
[
"Taha",
"Ebtsam H.",
""
]
] | The aim of the present paper is to construct a field theory in the context of absolute parallelism (Teleparallel) geometry under the assumption that the canonical connection is semi-symmetric. The field equations are formulated using a suitable Lagrangian first proposed by Mikhail and Wanas. The mathematical and physical consequences arising from the obtained field equations are investigated. |
2302.04738 | Ming Zhang | Ming Zhang and Jie Jiang | Strong Cosmic Censorship in accelerating spacetime | 6 pages, 2 figures, matches published version | Sci. China-Phys. Mech. Astron. 66, 280412 (2023) | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-nd/4.0/ | It has been established that Strong Cosmic Censorship Conjecture (SCCC) is
respected by an asymptotically flat black hole with charge, but violated by a
charged asymptotically de Sitter black hole. We studied the instability of the
Cauchy horizon for an accelerating black hole in Einstein theory conformally
coupled with a scalar field. The black hole is uncharged while having inner,
outer, and acceleration horizons. In the limit of vanishing acceleration,
denoted by $A \to 0$, it becomes asymptotically flat and extremal, with its
acceleration horizon vanishing as well. By exploring the perturbation of the
massless scalar field upon the accelerating black hole, whose decay rate is
governed by the quasinormal mode spectra, we show that the SCCC is violated in
the near-extremal regime and also in the $A\to 0^+$ limit. Our result is the
first observation of a black hole violating the SCCC in an almost
asymptotically Minkowskian flat regime, as well as the first example of a black
hole violating the SCCC with neither charge nor rotation.
| [
{
"created": "Thu, 9 Feb 2023 16:18:30 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Jul 2023 14:59:23 GMT",
"version": "v2"
}
] | 2023-07-06 | [
[
"Zhang",
"Ming",
""
],
[
"Jiang",
"Jie",
""
]
] | It has been established that Strong Cosmic Censorship Conjecture (SCCC) is respected by an asymptotically flat black hole with charge, but violated by a charged asymptotically de Sitter black hole. We studied the instability of the Cauchy horizon for an accelerating black hole in Einstein theory conformally coupled with a scalar field. The black hole is uncharged while having inner, outer, and acceleration horizons. In the limit of vanishing acceleration, denoted by $A \to 0$, it becomes asymptotically flat and extremal, with its acceleration horizon vanishing as well. By exploring the perturbation of the massless scalar field upon the accelerating black hole, whose decay rate is governed by the quasinormal mode spectra, we show that the SCCC is violated in the near-extremal regime and also in the $A\to 0^+$ limit. Our result is the first observation of a black hole violating the SCCC in an almost asymptotically Minkowskian flat regime, as well as the first example of a black hole violating the SCCC with neither charge nor rotation. |
gr-qc/0609057 | Mikhail Kagan | Martin Bojowald, Hector H. Hern\'andez, Mikhail Kagan, Parampreet
Singh, and Aureliano Skirzewski | Hamiltonian cosmological perturbation theory with loop quantum gravity
corrections | 24 pages, 1 figure | Phys.Rev.D74:123512,2006 | 10.1103/PhysRevD.74.123512 | IGPG-06/9-7 | gr-qc astro-ph hep-ph | null | Cosmological perturbation equations are derived systematically in a canonical
scheme based on Ashtekar variables. A comparison with the covariant derivation
and various subtleties in the calculation and choice of gauges are pointed out.
Nevertheless, the treatment is more systematic when correction terms of
canonical quantum gravity are to be included. This is done throughout the paper
for one characteristic modification expected from loop quantum gravity.
| [
{
"created": "Fri, 15 Sep 2006 19:59:19 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Sep 2006 21:04:05 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Bojowald",
"Martin",
""
],
[
"Hernández",
"Hector H.",
""
],
[
"Kagan",
"Mikhail",
""
],
[
"Singh",
"Parampreet",
""
],
[
"Skirzewski",
"Aureliano",
""
]
] | Cosmological perturbation equations are derived systematically in a canonical scheme based on Ashtekar variables. A comparison with the covariant derivation and various subtleties in the calculation and choice of gauges are pointed out. Nevertheless, the treatment is more systematic when correction terms of canonical quantum gravity are to be included. This is done throughout the paper for one characteristic modification expected from loop quantum gravity. |
1904.09550 | Alessandro Nagar | Alessandro Nagar, Geraint Pratten, Gunnar Riemenschneider, and
Rossella Gamba | A Multipolar Effective One Body Model for Non-Spinning Black Hole
Binaries | 24 pages, 18 figures. Improved figures and presentation. Submitted to
Phys. Rev. D | Phys. Rev. D 101, 024041 (2020) | 10.1103/PhysRevD.101.024041 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce \TEOBiResumSM{}, a nonspinning inspiral-merger-ringdown waveform
model built within the effective one body (EOB) framework that includes
gravitational waveform modes beyond the dominant quadrupole $(\ell,|m|) =
(2,2)$. The model incorporates: (i) an improved Pad\'e resummation of the
factorized waveform amplitudes $\rho_{\ell m}^{\rm orb}$ entering the
EOB-resummed waveform where the 3PN, mass-ratio dependent, terms are hybridized
with test-mass limit terms up to 6PN relative order for most of the multipoles
up to $\ell=6$ included; (ii) an improved determination of the effective 5PN
function $a_6^c(\nu)$ entering the EOB interaction potential done using the
most recent, error-controlled, nonspinning numerical relativity (NR) waveforms
from the Simulating eXtreme Spacetimes (SXS) collaboration; and (iii) a
NR-informed phenomenological description of the multipolar ringdown. Such
representation stems from 19 NR waveforms with mass ratios up to $m_1/m_2=18$
as well as test-mass waveform data, although it does not incorporate
mode-mixing effects. The NR-completed higher modes through merger and ringdown
considered here are: $(\ell,|m|) = \lbrace (2,1), (3,3), (3,2),(3,1),(4,4),
(4,3),(4,2), (4,1),(5,5)\rbrace$. For simplicity, the other subdominant modes,
up to $\ell=8$, are approximated by the corresponding, purely analytical,
factorized and resummed EOB waveform. To attempt an estimate of (some of) the
underlying analytic uncertainties of the model, we also contrast the effect of
the 6PN-hybrid Pad\'e-resummed $\rho_{\ell m}$'s with the standard $3^{+2}$PN,
Taylor-expanded, ones used in previous EOB works. The maximum unfaithfulness
$\bar{F}$ against the SXS waveforms including all NR-completed modes up to
$\ell=m=5$ is always $\lesssim 2\%$ for binaries with total mass $M$ as $50
M_{\odot} \leq M \lesssim 200 M_{\odot}$.
| [
{
"created": "Sun, 21 Apr 2019 07:01:24 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Nov 2019 10:52:25 GMT",
"version": "v2"
}
] | 2020-01-29 | [
[
"Nagar",
"Alessandro",
""
],
[
"Pratten",
"Geraint",
""
],
[
"Riemenschneider",
"Gunnar",
""
],
[
"Gamba",
"Rossella",
""
]
] | We introduce \TEOBiResumSM{}, a nonspinning inspiral-merger-ringdown waveform model built within the effective one body (EOB) framework that includes gravitational waveform modes beyond the dominant quadrupole $(\ell,|m|) = (2,2)$. The model incorporates: (i) an improved Pad\'e resummation of the factorized waveform amplitudes $\rho_{\ell m}^{\rm orb}$ entering the EOB-resummed waveform where the 3PN, mass-ratio dependent, terms are hybridized with test-mass limit terms up to 6PN relative order for most of the multipoles up to $\ell=6$ included; (ii) an improved determination of the effective 5PN function $a_6^c(\nu)$ entering the EOB interaction potential done using the most recent, error-controlled, nonspinning numerical relativity (NR) waveforms from the Simulating eXtreme Spacetimes (SXS) collaboration; and (iii) a NR-informed phenomenological description of the multipolar ringdown. Such representation stems from 19 NR waveforms with mass ratios up to $m_1/m_2=18$ as well as test-mass waveform data, although it does not incorporate mode-mixing effects. The NR-completed higher modes through merger and ringdown considered here are: $(\ell,|m|) = \lbrace (2,1), (3,3), (3,2),(3,1),(4,4), (4,3),(4,2), (4,1),(5,5)\rbrace$. For simplicity, the other subdominant modes, up to $\ell=8$, are approximated by the corresponding, purely analytical, factorized and resummed EOB waveform. To attempt an estimate of (some of) the underlying analytic uncertainties of the model, we also contrast the effect of the 6PN-hybrid Pad\'e-resummed $\rho_{\ell m}$'s with the standard $3^{+2}$PN, Taylor-expanded, ones used in previous EOB works. The maximum unfaithfulness $\bar{F}$ against the SXS waveforms including all NR-completed modes up to $\ell=m=5$ is always $\lesssim 2\%$ for binaries with total mass $M$ as $50 M_{\odot} \leq M \lesssim 200 M_{\odot}$. |
0802.1201 | Emanuele Alesci | Emanuele Alesci | Tensorial Structure of the LQG graviton propagator | 4 pages,; to appear in the proceedings of the II Stueckelberg
Workshop, Int.J.Mod.Phys.A | Int.J.Mod.Phys.A23:1209-1213,2008 | 10.1142/S0217751X0804007X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review the construction of the tensorial structure of the graviton
propagator in the context of loop quantum gravity and spinfoam formalism. The
main result of this analysis is that applying the same strategy used to compute
the diagonal terms, the Barrett-Crane vertex is unable to yield the correct
propagator in the long distance limit. The problem is in the
intertwiner-independence of the Barrett-Crane vertex. We also review the
asymptotic behavior of an alternative vertex that is able to give the correct
propagator.
| [
{
"created": "Fri, 8 Feb 2008 18:52:34 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Alesci",
"Emanuele",
""
]
] | We review the construction of the tensorial structure of the graviton propagator in the context of loop quantum gravity and spinfoam formalism. The main result of this analysis is that applying the same strategy used to compute the diagonal terms, the Barrett-Crane vertex is unable to yield the correct propagator in the long distance limit. The problem is in the intertwiner-independence of the Barrett-Crane vertex. We also review the asymptotic behavior of an alternative vertex that is able to give the correct propagator. |
1504.03305 | Antony Speranza | Antony J. Speranza | Ponderable aether | 22 pages (excluding references). Comments welcome | null | 10.1088/1475-7516/2015/08/016 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a Lorentz-violating theory of gravity where the aether vector is
taken to be nondynamical. This "ponderable aether theory" is almost the same as
Einstein-aether theory (where the aether vector is dynamical), but involves
additional integration constants arising due to the loss of initial value
constraints. One of these produces an effective energy density for the aether
fluid, similar to the appearance of dark matter in projectable Ho\v{r}ava
gravity and the mimetic dark matter theory. Here we investigate the extent to
which this energy density can reproduce the phenomenology of dark matter.
Although it is indistinguishable from cold dark matter in homogeneous,
isotropic cosmology, it encounters phenomenological problems in both
spherically symmetric configurations and cosmological perturbations.
Furthermore, inflationary considerations lead us to expect a tiny value for the
ponderable aether energy density today unless a sourcing effect is added to the
theory. The theory then effectively reduces to dynamical Einstein-aether
theory, rendering moot the question of whether an aether must be dynamical in
order to be consistent.
| [
{
"created": "Mon, 13 Apr 2015 19:27:52 GMT",
"version": "v1"
}
] | 2015-08-19 | [
[
"Speranza",
"Antony J.",
""
]
] | We consider a Lorentz-violating theory of gravity where the aether vector is taken to be nondynamical. This "ponderable aether theory" is almost the same as Einstein-aether theory (where the aether vector is dynamical), but involves additional integration constants arising due to the loss of initial value constraints. One of these produces an effective energy density for the aether fluid, similar to the appearance of dark matter in projectable Ho\v{r}ava gravity and the mimetic dark matter theory. Here we investigate the extent to which this energy density can reproduce the phenomenology of dark matter. Although it is indistinguishable from cold dark matter in homogeneous, isotropic cosmology, it encounters phenomenological problems in both spherically symmetric configurations and cosmological perturbations. Furthermore, inflationary considerations lead us to expect a tiny value for the ponderable aether energy density today unless a sourcing effect is added to the theory. The theory then effectively reduces to dynamical Einstein-aether theory, rendering moot the question of whether an aether must be dynamical in order to be consistent. |
2209.11358 | Abbas Sherif | Abbas M. Sherif and Peter K. S. Dunsby | Horizon area bound and MOTS stability in locally rotationally symmetric
solutions | Area bound of Proposition III.1 has been revised, and subsequently
affected results have been amended accordingly. Some rewriting of the texts
surrounding the MOTS stability operator has been done. This version matches
the version that has been accepted for publication in Classical and Quantum
Gravity | null | 10.1088/1361-6382/acb195 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In this paper, we study the stability of marginally outer trapped surfaces
(MOTS), foliating horizons of the form $r=X(\tau)$, embedded in locally
rotationally symmetric class II perfect fluid spacetimes. An upper bound on the
area of stable MOTS is obtained. It is shown that any stable MOTS of the types
considered in these spacetimes must be strictly stably outermost, that is,
there are no MOTS ``outside" of and homologous to $\mathcal{S}$. Aspects of the
topology of the MOTS, as well as the case when an extension is made to
imperfect fluids, are discussed. Some non-existence results are also obtained.
Finally, the ``growth" of certain matter and curvature quantities on certain
unstable MOTS are provided under specified conditions.
| [
{
"created": "Fri, 23 Sep 2022 01:04:37 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Jan 2023 13:22:25 GMT",
"version": "v2"
}
] | 2023-01-11 | [
[
"Sherif",
"Abbas M.",
""
],
[
"Dunsby",
"Peter K. S.",
""
]
] | In this paper, we study the stability of marginally outer trapped surfaces (MOTS), foliating horizons of the form $r=X(\tau)$, embedded in locally rotationally symmetric class II perfect fluid spacetimes. An upper bound on the area of stable MOTS is obtained. It is shown that any stable MOTS of the types considered in these spacetimes must be strictly stably outermost, that is, there are no MOTS ``outside" of and homologous to $\mathcal{S}$. Aspects of the topology of the MOTS, as well as the case when an extension is made to imperfect fluids, are discussed. Some non-existence results are also obtained. Finally, the ``growth" of certain matter and curvature quantities on certain unstable MOTS are provided under specified conditions. |
1208.1764 | Florian Kuhnel | Florian Kuhnel | On Instability of Certain Bi-Metric and Massive-Gravity Theories | 4 pages, 2 figures; v2: minor changes to match PRD version | null | 10.1103/PhysRevD.88.064024 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Stability about cosmological background solutions to the bi-metric
Hassan-Rosen theory is studied. The results of this analysis are presented, and
it is shown that a large class of cosmological backgrounds is classically
unstable. This sets serious doubts on the physical viability of the
Hassan-Rosen theory - and in turn also of the de Rham-Gadabaze-Tolley model, to
which the mentioned theory is parent. A way to overcome this instability by
means of curvature-type deformations is discussed.
| [
{
"created": "Wed, 8 Aug 2012 20:00:08 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Aug 2013 21:30:11 GMT",
"version": "v2"
}
] | 2013-09-18 | [
[
"Kuhnel",
"Florian",
""
]
] | Stability about cosmological background solutions to the bi-metric Hassan-Rosen theory is studied. The results of this analysis are presented, and it is shown that a large class of cosmological backgrounds is classically unstable. This sets serious doubts on the physical viability of the Hassan-Rosen theory - and in turn also of the de Rham-Gadabaze-Tolley model, to which the mentioned theory is parent. A way to overcome this instability by means of curvature-type deformations is discussed. |
2003.01542 | Cristian Armendariz-Picon | C. Armendariz-Picon | On the Expected Backreaction During Preheating | 40 pages, 10 figures. v2: Replaced with published version | null | 10.1088/1475-7516/2020/05/035 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In previous work we argued that the correct procedure to predict the
gravitational wave signal from preheating after inflation rests on the in-in
formalism. We extend here our previous analysis to include the backreaction of
the produced matter on the motion of the inflaton and the expansion of the
universe, and study how the latter affect the spectrum of the resulting
gravitational waves. The addition of backreaction demands the appropriate
renormalization of divergent expectation values, which we regularize by
preserving diffeomorphism invariance in a manner that is amenable to numerical
integration. The very same calculation also allows us to determine for which
strength of the inflaton to matter couplings reheating is successful. We
illustrate our results with the scalar version of the Starobinsky model of
inflation, and observe that it is hard to reheat the universe while keeping
radiative corrections under control.
| [
{
"created": "Mon, 2 Mar 2020 17:41:22 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Nov 2020 14:28:21 GMT",
"version": "v2"
}
] | 2020-11-26 | [
[
"Armendariz-Picon",
"C.",
""
]
] | In previous work we argued that the correct procedure to predict the gravitational wave signal from preheating after inflation rests on the in-in formalism. We extend here our previous analysis to include the backreaction of the produced matter on the motion of the inflaton and the expansion of the universe, and study how the latter affect the spectrum of the resulting gravitational waves. The addition of backreaction demands the appropriate renormalization of divergent expectation values, which we regularize by preserving diffeomorphism invariance in a manner that is amenable to numerical integration. The very same calculation also allows us to determine for which strength of the inflaton to matter couplings reheating is successful. We illustrate our results with the scalar version of the Starobinsky model of inflation, and observe that it is hard to reheat the universe while keeping radiative corrections under control. |
gr-qc/9512014 | Vladimir Dzhunushaliev | V.D. Dzhunushaliev | Kolmogorov Algorithmic Complexity and its Probability Interpretation in
Quantum Gravity | 11 pages, REVTEX, some corrections in text | Class.Quant.Grav. 15 (1998) 603 | 10.1088/0264-9381/15/3/011 | null | gr-qc | null | The quantum gravity has great difficulties with application of the
probability notion. In given article this problem is analyzed according to
algorithmic viewpoint. According to A.N. Kolmogorov, the probability notion can
be connected with algorithmic complexity of given object. The paper proposes an
interpretation of quantum gravity, according to which an appearance of
something corresponds to its Kolmogorov's algorithmic complexity. By this
viewpoint the following questions are considered: the quantum transition with
supplementary coordinates splitting off, the algorithmic complexity of the
Schwarzschild black hole is estimated, the redefinition of the Feynman path
integral, the quantum birth of the Euclidean Universe with the following
changing of the metric signature.
| [
{
"created": "Thu, 7 Dec 1995 03:41:39 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Apr 1997 02:58:09 GMT",
"version": "v2"
}
] | 2009-10-28 | [
[
"Dzhunushaliev",
"V. D.",
""
]
] | The quantum gravity has great difficulties with application of the probability notion. In given article this problem is analyzed according to algorithmic viewpoint. According to A.N. Kolmogorov, the probability notion can be connected with algorithmic complexity of given object. The paper proposes an interpretation of quantum gravity, according to which an appearance of something corresponds to its Kolmogorov's algorithmic complexity. By this viewpoint the following questions are considered: the quantum transition with supplementary coordinates splitting off, the algorithmic complexity of the Schwarzschild black hole is estimated, the redefinition of the Feynman path integral, the quantum birth of the Euclidean Universe with the following changing of the metric signature. |
2001.02016 | Andronikos Paliathanasis | Andronikos Paliathanasis | Extended analysis for the Evolution of the Cosmological history in
Einstein-aether Scalar Field theory | 19 pages, 7 figures, new appendix, discussion improved, version
accepted for publication by Physical Review D | Phys. Rev. D 101, 064008 (2020) | 10.1103/PhysRevD.101.064008 | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider an Einstein-aether scalar field cosmological model where the
aether and the scalar field are interacting. The model of our consideration
consists the two different interacting models proposed in the literature by
Kanno et al. and by Donnelly et al. We perform an extended analysis for the
cosmological evolution as it is provided by the field equations by using
methods from dynamical systems; specifically, we determine the stationary
points and we perform the stability analysis of those exact solutions.
| [
{
"created": "Tue, 7 Jan 2020 13:20:45 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Feb 2020 08:14:53 GMT",
"version": "v2"
}
] | 2020-03-11 | [
[
"Paliathanasis",
"Andronikos",
""
]
] | We consider an Einstein-aether scalar field cosmological model where the aether and the scalar field are interacting. The model of our consideration consists the two different interacting models proposed in the literature by Kanno et al. and by Donnelly et al. We perform an extended analysis for the cosmological evolution as it is provided by the field equations by using methods from dynamical systems; specifically, we determine the stationary points and we perform the stability analysis of those exact solutions. |
gr-qc/0411145 | Robert Beig | R.Beig, B.G.Schmidt | Relativistic Elastostatics I: Bodies in Rigid Rotation | 25 pages | Class.Quant.Grav. 22 (2005) 2249-2268 | 10.1088/0264-9381/22/11/021 | null | gr-qc | null | We consider elastic bodies in rigid rotation, both nonrelativistically and in
special relativity. Assuming a body to be in its natural state in the absence
of rotation, we prove the existence of solutions to the elastic field equations
for small angular velocity.
| [
{
"created": "Tue, 30 Nov 2004 11:19:28 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Apr 2005 07:00:57 GMT",
"version": "v2"
},
{
"created": "Thu, 19 May 2005 08:48:11 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Beig",
"R.",
""
],
[
"Schmidt",
"B. G.",
""
]
] | We consider elastic bodies in rigid rotation, both nonrelativistically and in special relativity. Assuming a body to be in its natural state in the absence of rotation, we prove the existence of solutions to the elastic field equations for small angular velocity. |
2208.10953 | Allan Alinea | Allan L. Alinea and Mark Ruel D. Chua | Extending the symmetry of the massless Klein-Gordon equation under the
general disformal transformation | 14 pages, accepted for publication in International Journal of Modern
Physics A, deleted some unimportant details, clarified that the
`orthogonality condition' does not make the field overdetermined, rewritten
parts for clarity | Int. J. Mod. Phys. A 38 01 (2023) 2350004 | 10.1142/S0217751X23500045 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The Klein-Gordon equation, one of the most fundamental equations in field
theory, is known to be not invariant under conformal transformation. However,
its massless limit exhibits symmetry under Bekenstein's disformal
transformation, subject to some conditions on the disformal part of the metric
variation. In this study, we explore the symmetry of the Klein-Gordon equation
under the general disformal transformation encompassing that of Bekenstein and
a hierarchy of `sub-generalisations' explored in the literature (within the
context of inflationary cosmology and scalar-tensor theories). We find that the
symmetry in the massless limit can be extended under this generalisation
provided that the disformal factors takes a special form in relation to the
conformal factor. Upon settling the effective extension of symmetry, we
investigate the invertibility of the general disformal transformation to avoid
propagating non-physical degrees of freedom upon changing the metric. We derive
the inverse transformation and the accompanying restrictions that make this
inverse possible.
| [
{
"created": "Tue, 23 Aug 2022 13:23:06 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Jan 2023 01:51:21 GMT",
"version": "v2"
}
] | 2023-03-14 | [
[
"Alinea",
"Allan L.",
""
],
[
"Chua",
"Mark Ruel D.",
""
]
] | The Klein-Gordon equation, one of the most fundamental equations in field theory, is known to be not invariant under conformal transformation. However, its massless limit exhibits symmetry under Bekenstein's disformal transformation, subject to some conditions on the disformal part of the metric variation. In this study, we explore the symmetry of the Klein-Gordon equation under the general disformal transformation encompassing that of Bekenstein and a hierarchy of `sub-generalisations' explored in the literature (within the context of inflationary cosmology and scalar-tensor theories). We find that the symmetry in the massless limit can be extended under this generalisation provided that the disformal factors takes a special form in relation to the conformal factor. Upon settling the effective extension of symmetry, we investigate the invertibility of the general disformal transformation to avoid propagating non-physical degrees of freedom upon changing the metric. We derive the inverse transformation and the accompanying restrictions that make this inverse possible. |
2204.05174 | Sudipta Das | Srijita Sinha, Manisha Banerjee, Sudipta Das | Perturbation in an interacting dark universe | 10 pages, 5 figures. arXiv admin note: text overlap with
arXiv:2110.02666 | Phys.Dark Univ. 42 (2023) 101273 | 10.1016/j.dark.2023.101273 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we have considered an interacting model of dark energy and have
looked into the evolution of the dark sectors. By solving the perturbation
equations numerically, we have studied the imprints on the growth of matter as
well as dark energy fluctuations. It has been found that for higher rate of
interaction strength for the coupling term, visible imprints on the dark energy
density fluctuations are observed at the early epochs of evolution.
| [
{
"created": "Mon, 11 Apr 2022 15:07:52 GMT",
"version": "v1"
}
] | 2024-05-30 | [
[
"Sinha",
"Srijita",
""
],
[
"Banerjee",
"Manisha",
""
],
[
"Das",
"Sudipta",
""
]
] | In this paper we have considered an interacting model of dark energy and have looked into the evolution of the dark sectors. By solving the perturbation equations numerically, we have studied the imprints on the growth of matter as well as dark energy fluctuations. It has been found that for higher rate of interaction strength for the coupling term, visible imprints on the dark energy density fluctuations are observed at the early epochs of evolution. |
1805.11042 | Everton Murilo Carvalho Abreu | E. M. C. Abreu, A. C. R. Mendes, G. Oliveira-Neto, J. Ananias Neto, L.
G. Rezende Rodrigues and M. Silva de Oliveira | Ho\v{r}ava-Lifshitz cosmological models in noncommutative space-times | 27 pages. Preprint format | null | 10.1007/s10714-019-2577-3 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we will analyze a noncommutative (NC) version of the
Friedmann-Robert-Walker cosmological models within the gravitational
Ho\v{r}ava-Lifshitz theory. The matter content of the models is described by a
perfect fluid and the constant curvature of the spatial sections may be
positive, negative or zero. In order to obtain this theory, we will use the
Faddeev-Jackiw symplectic formalism to introduce, naturally, space-time
noncommutativity inside the equations that provide the dynamics of the theory.
We will investigate, in details, the classical field equations of a particular
version of the NC models. The equations will be modified, with respect to the
commutative ones, by the introduction of a NC parameter. We will demonstrate
that various NC models, with different types of matter and spatial constant
curvatures, show several interesting and new results relative to the
corresponding commutative ones. We will pay special attention to some cases,
where the NC model predicts a scale factor accelerated expansion, which may
describe the current state of our Universe.
| [
{
"created": "Wed, 23 May 2018 18:50:27 GMT",
"version": "v1"
}
] | 2019-08-14 | [
[
"Abreu",
"E. M. C.",
""
],
[
"Mendes",
"A. C. R.",
""
],
[
"Oliveira-Neto",
"G.",
""
],
[
"Neto",
"J. Ananias",
""
],
[
"Rodrigues",
"L. G. Rezende",
""
],
[
"de Oliveira",
"M. Silva",
""
]
] | In this work, we will analyze a noncommutative (NC) version of the Friedmann-Robert-Walker cosmological models within the gravitational Ho\v{r}ava-Lifshitz theory. The matter content of the models is described by a perfect fluid and the constant curvature of the spatial sections may be positive, negative or zero. In order to obtain this theory, we will use the Faddeev-Jackiw symplectic formalism to introduce, naturally, space-time noncommutativity inside the equations that provide the dynamics of the theory. We will investigate, in details, the classical field equations of a particular version of the NC models. The equations will be modified, with respect to the commutative ones, by the introduction of a NC parameter. We will demonstrate that various NC models, with different types of matter and spatial constant curvatures, show several interesting and new results relative to the corresponding commutative ones. We will pay special attention to some cases, where the NC model predicts a scale factor accelerated expansion, which may describe the current state of our Universe. |
gr-qc/0212110 | Vladimir M. Khatsymovsky | V.M.Khatsymovsky | Area expectation values in quantum area Regge calculus | 9 pages, LaTeX, possible relation to quantisation of the usual
length-based Regge calculus is discussed | Phys.Lett. B560 (2003) 245-251 | 10.1016/S0370-2693(03)00439-8 | null | gr-qc | null | The Regge calculus generalised to independent area tensor variables is
considered. The continuous time limit is found and formal Feynman path integral
measure corresponding to the canonical quantisation is written out. The quantum
measure in the completely discrete theory is found which possesses the property
to lead to the Feynman path integral in the continuous time limit whatever
coordinate is chosen as time. This measure can be well defined by passing to
the integration over imaginary field variables (area tensors). Averaging with
the help of this measure gives finite expectation values for areas.
| [
{
"created": "Thu, 26 Dec 2002 18:25:27 GMT",
"version": "v1"
},
{
"created": "Fri, 27 Dec 2002 06:36:56 GMT",
"version": "v2"
},
{
"created": "Thu, 6 Mar 2003 08:19:28 GMT",
"version": "v3"
}
] | 2009-11-07 | [
[
"Khatsymovsky",
"V. M.",
""
]
] | The Regge calculus generalised to independent area tensor variables is considered. The continuous time limit is found and formal Feynman path integral measure corresponding to the canonical quantisation is written out. The quantum measure in the completely discrete theory is found which possesses the property to lead to the Feynman path integral in the continuous time limit whatever coordinate is chosen as time. This measure can be well defined by passing to the integration over imaginary field variables (area tensors). Averaging with the help of this measure gives finite expectation values for areas. |
0709.1940 | Albert Roura | Albert Roura, Enric Verdaguer | Cosmological perturbations from stochastic gravity | 29 pages, REVTeX; minor changes, additional appendix with an
alternative proof of the equivalence between stochastic and quantum
correlation functions as well as an exact argument showing that the
correlation function of curvature perturbations remains constant in time for
superhorizon modes, which clarifies a recent claim in arXiv:0710.5342v1 | Phys.Rev.D78:064010,2008 | 10.1103/PhysRevD.78.064010 | LA-UR-07-6116 | gr-qc | null | In inflationary cosmological models driven by an inflaton field the origin of
the primordial inhomogeneities which are responsible for large scale structure
formation are the quantum fluctuations of the inflaton field. These are usually
computed using the standard theory of cosmological perturbations, where both
the gravitational and the inflaton fields are linearly perturbed and quantized.
The correlation functions for the primordial metric fluctuations and their
power spectrum are then computed. Here we introduce an alternative procedure
for computing the metric correlations based on the Einstein-Langevin equation
which emerges in the framework of stochastic semiclassical gravity. We show
that the correlation functions for the metric perturbations that follow from
the Einstein-Langevin formalism coincide with those obtained with the usual
quantization procedures when the scalar field perturbations are linearized.
This method is explicitly applied to a simple model of chaotic inflation
consisting of a Robertson-Walker background, which undergoes a quasi-de-Sitter
expansion, minimally coupled to a free massive quantum scalar field. The
technique based on the Einstein-Langevin equation can, however, deal naturally
with the perturbations of the scalar field even beyond the linear
approximation, as is actually required in inflationary models which are not
driven by an inflaton field such as Starobinsky's trace-anomaly driven
inflation or when calculating corrections due to non-linear quantum effects in
the usual inflaton driven models.
| [
{
"created": "Wed, 12 Sep 2007 18:24:14 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Feb 2008 19:32:38 GMT",
"version": "v2"
}
] | 2009-02-20 | [
[
"Roura",
"Albert",
""
],
[
"Verdaguer",
"Enric",
""
]
] | In inflationary cosmological models driven by an inflaton field the origin of the primordial inhomogeneities which are responsible for large scale structure formation are the quantum fluctuations of the inflaton field. These are usually computed using the standard theory of cosmological perturbations, where both the gravitational and the inflaton fields are linearly perturbed and quantized. The correlation functions for the primordial metric fluctuations and their power spectrum are then computed. Here we introduce an alternative procedure for computing the metric correlations based on the Einstein-Langevin equation which emerges in the framework of stochastic semiclassical gravity. We show that the correlation functions for the metric perturbations that follow from the Einstein-Langevin formalism coincide with those obtained with the usual quantization procedures when the scalar field perturbations are linearized. This method is explicitly applied to a simple model of chaotic inflation consisting of a Robertson-Walker background, which undergoes a quasi-de-Sitter expansion, minimally coupled to a free massive quantum scalar field. The technique based on the Einstein-Langevin equation can, however, deal naturally with the perturbations of the scalar field even beyond the linear approximation, as is actually required in inflationary models which are not driven by an inflaton field such as Starobinsky's trace-anomaly driven inflation or when calculating corrections due to non-linear quantum effects in the usual inflaton driven models. |
1011.4159 | Francisco Lobo | Nadiezhda Montelongo Garc\'ia, Tiberiu Harko, Francisco S. N. Lobo,
Jos\'e P. Mimoso | Energy conditions in modified Gauss-Bonnet gravity | 9 pages, 8 figures. V2: minor additions and corrections; to appear in
PRD | Phys.Rev.D83:104032,2011 | 10.1103/PhysRevD.83.104032 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In considering alternative higher-order gravity theories, one is liable to be
motivated in pursuing models consistent and inspired by several candidates of a
fundamental theory of quantum gravity. Indeed, motivations from string/M-theory
predict that scalar field couplings with the Gauss-Bonnet invariant, G, are
important in the appearance of non-singular early time cosmologies. In this
work, we discuss the viability of an interesting alternative gravitational
theory, namely, modified Gauss-Bonnet gravity or f(G) gravity. We consider
specific realistic forms of f(G) analyzed in the literature that account for
the late-time cosmic acceleration and that have been found to cure the
finite-time future singularities present in the dark energy models. We present
the general inequalities imposed by the energy conditions and use the recent
estimated values of the Hubble, deceleration, jerk and snap parameters to
examine the viability of the above-mentioned forms of f(G) imposed by the weak
energy condition.
| [
{
"created": "Thu, 18 Nov 2010 09:21:31 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Apr 2011 21:49:37 GMT",
"version": "v2"
}
] | 2015-03-17 | [
[
"García",
"Nadiezhda Montelongo",
""
],
[
"Harko",
"Tiberiu",
""
],
[
"Lobo",
"Francisco S. N.",
""
],
[
"Mimoso",
"José P.",
""
]
] | In considering alternative higher-order gravity theories, one is liable to be motivated in pursuing models consistent and inspired by several candidates of a fundamental theory of quantum gravity. Indeed, motivations from string/M-theory predict that scalar field couplings with the Gauss-Bonnet invariant, G, are important in the appearance of non-singular early time cosmologies. In this work, we discuss the viability of an interesting alternative gravitational theory, namely, modified Gauss-Bonnet gravity or f(G) gravity. We consider specific realistic forms of f(G) analyzed in the literature that account for the late-time cosmic acceleration and that have been found to cure the finite-time future singularities present in the dark energy models. We present the general inequalities imposed by the energy conditions and use the recent estimated values of the Hubble, deceleration, jerk and snap parameters to examine the viability of the above-mentioned forms of f(G) imposed by the weak energy condition. |
0812.2332 | Molin Liu | Molin Liu, Jianbo Lu, Yuanxing Gui | The Influence of Free Quintessence on Gravitational Frequency Shift and
Deflection of Light with 4D momentum | 12 pages, 2 figures, 4 tables. European Physical Journal C in press | Eur.Phys.J.C59:107-116,2009 | 10.1140/epjc/s10052-008-0800-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on the 4D momentum, the influence of quintessence on the gravitational
frequency shift and the deflection of light are examined in modified
Schwarzschild space. We find that the frequency of photon depends on the state
parameter of quintessence $w_q$: the frequency increases for $-1<w_q<-1/3$ and
decreases for $-1/3<w_q<0$. Meanwhile, we adopt an integral power number $a$
($a = 3\omega_q + 2$) to solve the orbital equation of photon. The photon's
potentials become higher with the decrease of $\omega_q$. The behavior of
bending light depends on the state parameter $\omega_q$ sensitively. In
particular, for the case of $\omega_q = -1$, there is no influence on the
deflection of light by quintessence. Else, according to the H-masers of GP-A
redshift experiment and the long-baseline interferometry, the constraints on
the quintessence field in Solar system are presented here.
| [
{
"created": "Fri, 12 Dec 2008 10:00:43 GMT",
"version": "v1"
}
] | 2009-03-20 | [
[
"Liu",
"Molin",
""
],
[
"Lu",
"Jianbo",
""
],
[
"Gui",
"Yuanxing",
""
]
] | Based on the 4D momentum, the influence of quintessence on the gravitational frequency shift and the deflection of light are examined in modified Schwarzschild space. We find that the frequency of photon depends on the state parameter of quintessence $w_q$: the frequency increases for $-1<w_q<-1/3$ and decreases for $-1/3<w_q<0$. Meanwhile, we adopt an integral power number $a$ ($a = 3\omega_q + 2$) to solve the orbital equation of photon. The photon's potentials become higher with the decrease of $\omega_q$. The behavior of bending light depends on the state parameter $\omega_q$ sensitively. In particular, for the case of $\omega_q = -1$, there is no influence on the deflection of light by quintessence. Else, according to the H-masers of GP-A redshift experiment and the long-baseline interferometry, the constraints on the quintessence field in Solar system are presented here. |
2006.02944 | J\'er\'emy Auffinger | Alexandre Arbey, J\'er\'emy Auffinger | Detecting Planet 9 via Hawking radiation | 15 pages, 6 figures, text completed and units corrected | null | null | null | gr-qc astro-ph.EP astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Concordant evidence points towards the existence of a ninth planet in the
Solar System at more than $400\,$AU from the Sun. In particular,
trans-Neptunian object orbits are perturbed by the presence of a putative
gravitational source. Since this planet has not yet been observationally found
with conventional telescope research, it has been argued that it could be a
dark compact object, namely a black hole of probably primordial origin. Within
this assumption, we discuss the possibility of detecting Planet 9 via a
sub-relativistic spacecraft fly-by and the measure of its Hawking radiation in
the radio band and conclude that it is too faint compared to the CMB. We thus
present other perspectives with rather a satellite mission and conclude that
smaller black holes would give much more interesting signals. We emphasize the
importance of the study of such Hawking radiation laboratories in the Solar
System.
| [
{
"created": "Thu, 4 Jun 2020 15:27:49 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Jan 2021 10:46:33 GMT",
"version": "v2"
}
] | 2021-01-29 | [
[
"Arbey",
"Alexandre",
""
],
[
"Auffinger",
"Jérémy",
""
]
] | Concordant evidence points towards the existence of a ninth planet in the Solar System at more than $400\,$AU from the Sun. In particular, trans-Neptunian object orbits are perturbed by the presence of a putative gravitational source. Since this planet has not yet been observationally found with conventional telescope research, it has been argued that it could be a dark compact object, namely a black hole of probably primordial origin. Within this assumption, we discuss the possibility of detecting Planet 9 via a sub-relativistic spacecraft fly-by and the measure of its Hawking radiation in the radio band and conclude that it is too faint compared to the CMB. We thus present other perspectives with rather a satellite mission and conclude that smaller black holes would give much more interesting signals. We emphasize the importance of the study of such Hawking radiation laboratories in the Solar System. |
1704.01211 | Marcony Silva Cunha | V. B. Bezerra, H. R. Christiansen, M. S. Cunha, C. R. Muniz | Exact solutions and phenomenological constraints from massive scalars in
a Gravity's Rainbow spacetime | Rewritten and enlarged version. 17 pages, 1 figure, 1 table. Some
typos corrected. Final version to appear in Phys. Rev. D | Phys. Rev. D 96, 024018 (2017) | 10.1103/PhysRevD.96.024018 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain the exact (confluent Heun) solutions to the massive scalar field in
a Gravity's Rainbow Schwarzschild metric. With these solutions at hand, we
study the Hawking radiation resulting from the tunneling rate through the event
horizon. We show that the emission spectrum obeys non-extensive statistics and
is halted when a certain mass remnant is reached. Next, we infer constraints on
the rainbow parameters from recent LHC particle physics experiments and Hubble
STIS astrophysics measurements. Finally, we study the low frequency limit in
order to find the modified energy spectrum around the source.
| [
{
"created": "Tue, 4 Apr 2017 22:48:22 GMT",
"version": "v1"
},
{
"created": "Wed, 17 May 2017 05:38:42 GMT",
"version": "v2"
},
{
"created": "Fri, 30 Jun 2017 13:29:55 GMT",
"version": "v3"
},
{
"created": "Mon, 3 Jul 2017 03:33:41 GMT",
"version": "v4"
}
] | 2017-07-19 | [
[
"Bezerra",
"V. B.",
""
],
[
"Christiansen",
"H. R.",
""
],
[
"Cunha",
"M. S.",
""
],
[
"Muniz",
"C. R.",
""
]
] | We obtain the exact (confluent Heun) solutions to the massive scalar field in a Gravity's Rainbow Schwarzschild metric. With these solutions at hand, we study the Hawking radiation resulting from the tunneling rate through the event horizon. We show that the emission spectrum obeys non-extensive statistics and is halted when a certain mass remnant is reached. Next, we infer constraints on the rainbow parameters from recent LHC particle physics experiments and Hubble STIS astrophysics measurements. Finally, we study the low frequency limit in order to find the modified energy spectrum around the source. |
2010.08254 | Orlando Luongo | Kuantay Boshkayev, Orlando Luongo, Marco Muccino | Neutrino oscillation in the $q$-metric | 2 figures, 3 tables, accepted for publication in EPJC | null | 10.1140/epjc/s10052-020-08533-3 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate neutrino oscillation in the field of an axially symmetric
space-time, employing the so-called $q$-metric, in the context of general
relativity. Following the standard approach, we compute the phase shift
invoking the weak and strong field limits and small deformation. To do so, we
consider neutron stars, white dwarfs and supernovae as strong gravitational
regimes whereas the Solar System as weak field regime. We argue that the
inclusion of the quadrupole parameter leads to the modification of the
well-known results coming from the spherical solution due to the Schwarschild
space-time. Hence, we show that in the Solar System regime, considering the
Earth and Sun, there is a weak probability to detect deviations from the flat
case, differently from the case of neutron stars and white dwarfs in which this
probability is larger. Thus, we heuristically discuss some implications on
constraining the free parameters of the phase shift by means of astrophysical
neutrinos. A few consequences in cosmology and possible applications for future
space experiments are also discussed throughout the text.
| [
{
"created": "Fri, 16 Oct 2020 09:05:19 GMT",
"version": "v1"
}
] | 2020-12-02 | [
[
"Boshkayev",
"Kuantay",
""
],
[
"Luongo",
"Orlando",
""
],
[
"Muccino",
"Marco",
""
]
] | We investigate neutrino oscillation in the field of an axially symmetric space-time, employing the so-called $q$-metric, in the context of general relativity. Following the standard approach, we compute the phase shift invoking the weak and strong field limits and small deformation. To do so, we consider neutron stars, white dwarfs and supernovae as strong gravitational regimes whereas the Solar System as weak field regime. We argue that the inclusion of the quadrupole parameter leads to the modification of the well-known results coming from the spherical solution due to the Schwarschild space-time. Hence, we show that in the Solar System regime, considering the Earth and Sun, there is a weak probability to detect deviations from the flat case, differently from the case of neutron stars and white dwarfs in which this probability is larger. Thus, we heuristically discuss some implications on constraining the free parameters of the phase shift by means of astrophysical neutrinos. A few consequences in cosmology and possible applications for future space experiments are also discussed throughout the text. |
1003.1973 | Sean Gryb B | Sean B. Gryb | A Definition of Background Independence | 35 pages | Class. Quantum Grav. 27 (2010) 215018 | 10.1088/0264-9381/27/21/215018 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a definition for background (in)/dependence in dynamical theories
of the evolution of configurations that have a continuous symmetry and test
this definition on particle models and on gravity. Our definition draws from
Barbour's best-matching framework developed for the purpose of implementing
spatial and temporal relationalism. Among other interesting theories, general
relativity can be derived within this framework in novel ways. We study the
detailed canonical structure of a wide range of best matching theories and show
that their actions must have a local gauge symmetry. When gauge theory is
derived in this way, we obtain at the same time a conceptual framework for
distinguishing between background dependent and independent theories. Gauge
invariant observables satisfying Kuchar's criterion are identified and, in
simple cases, explicitly computed. We propose a procedure for inserting a
global background time into temporally relational theories. Interestingly,
using this procedure in general relativity leads to unimodular gravity.
| [
{
"created": "Tue, 9 Mar 2010 20:31:40 GMT",
"version": "v1"
}
] | 2010-10-13 | [
[
"Gryb",
"Sean B.",
""
]
] | We propose a definition for background (in)/dependence in dynamical theories of the evolution of configurations that have a continuous symmetry and test this definition on particle models and on gravity. Our definition draws from Barbour's best-matching framework developed for the purpose of implementing spatial and temporal relationalism. Among other interesting theories, general relativity can be derived within this framework in novel ways. We study the detailed canonical structure of a wide range of best matching theories and show that their actions must have a local gauge symmetry. When gauge theory is derived in this way, we obtain at the same time a conceptual framework for distinguishing between background dependent and independent theories. Gauge invariant observables satisfying Kuchar's criterion are identified and, in simple cases, explicitly computed. We propose a procedure for inserting a global background time into temporally relational theories. Interestingly, using this procedure in general relativity leads to unimodular gravity. |
1704.03719 | LVC Publications | The LIGO Scientific Collaboration and the Virgo Collaboration: B. P.
Abbott, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, C. Adams, T. Adams,
P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Afrough, B. Agarwal,
K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, B.
Allen, G. Allen, A. Allocca, H. Almoubayyed, P. A. Altin, A. Amato, A.
Ananyeva, S. B. Anderson, W. G. Anderson, S. Antier, S. Appert, K. Arai, M.
C. Araya, J. S. Areeda, N. Arnaud, K. G. Arun, S. Ascenzi, G. Ashton, M. Ast,
S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert, K. AultONeal, A.
Avila-Alvarez, S. Babak, P. Bacon, M. K. M. Bader, S. Bae, P. T. Baker, F.
Baldaccini, G. Ballardin, S. W. Ballmer, S. Banagiri, J. C. Barayoga, S. E.
Barclay, B. C. Barish, D. Barker, F. Barone, B. Barr, L. Barsotti, M.
Barsuglia, D. Barta, J. Bartlett, I. Bartos, R. Bassiri, A. Basti, J. C.
Batch, C. Baune, M. Bawaj, M. Bazzan, B. B'ecsy, C. Beer, M. Bejger, I.
Belahcene, A. S. Bell, B. K. Berger, G. Bergmann, C. P. L. Berry, D.
Bersanetti, A. Bertolini, Z. B.Etienne, J. Betzwieser, S. Bhagwat, R.
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R. Brady, V. B. Braginsky, M. Branchesi, J. E. Brau, T. Briant, A. Brillet,
M. Brinkmann, V. Brisson, P. Brockill, J. E. Broida, A. F. Brooks, D. A.
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Bulik, H. J. Bulten, A. Buonanno, D. Buskulic, C. Buy, R. L. Byer, M. Cabero,
L. Cadonati, G. Cagnoli, C. Cahillane, J. Calder'on Bustillo, T. A.
Callister, E. Calloni, J. B. Camp, M. Canepa, P. Canizares, K. C. Cannon, H.
Cao, J. Cao, C. D. Capano, E. Capocasa, F. Carbognani, S. Caride, M. F.
Carney, J. Casanueva Diaz, C. Casentini, S. Caudill, M. Cavagli`a, F.
Cavalier, R. Cavalieri, G. Cella, C. B. Cepeda, L. Cerboni Baiardi, G.
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Chassande-Mottin, D. Chatterjee, B. D. Cheeseboro, H. Y. Chen, Y. Chen, H.-P.
Cheng, A. Chincarini, A. Chiummo, T. Chmiel, H. S. Cho, M. Cho, J. H. Chow,
N. Christensen, Q. Chu, A. J. K. Chua, S. Chua, A. K. W. Chung, S. Chung, G.
Ciani, R. Ciolfi, C. E. Cirelli, A. Cirone, F. Clara, J. A. Clark, F. Cleva,
C. Cocchieri, E. Coccia, P.-F. Cohadon, A. Colla, C. G. Collette, L. R.
Cominsky, M. Constancio Jr., L. Conti, S. J. Cooper, P. Corban, T. R.
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E. Creighton, T. D. Creighton, J. Cripe, S. G. Crowder, T. J. Cullen, A.
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E. Deelman, J. Degallaix, M. De Laurentis, S. Del'eglise, W. Del Pozzo, T.
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Giovanni, T. Di Girolamo, A. Di Lieto, S. Di Pace, I. Di Palma, F. Di Renzo,
Z. Doctor, V. Dolique, F. Donovan, K. L. Dooley, S. Doravari, I. Dorrington,
R. Douglas, M. Dovale 'Alvarez, T. P. Downes, M. Drago, R. W. P. Drever, J.
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Eikenberry, R. C. Essick, T. Etzel, M. Evans, T. M. Evans, M. Factourovich,
V. Fafone, H. Fair, S. Fairhurst, X. Fan, S. Farinon, B. Farr, W. M. Farr, E.
J. Fauchon-Jones, M. Favata, M. Fays, H. Fehrmann, J. Feicht, M. M. Fejer, A.
Fernandez-Galiana, I. Ferrante, E. C. Ferreira, F. Ferrini, F. Fidecaro, I.
Fiori, D. Fiorucci, R. P. Fisher, R. Flaminio, M. Fletcher, H. Fong, P. W. F.
Forsyth, S. S. Forsyth, J.-D. Fournier, S. Frasca, F. Frasconi, Z. Frei, A.
Freise, R. Frey, V. Frey, E. M. Fries, P. Fritschel, V. V. Frolov, P. Fulda,
M. Fyffe, H. Gabbard, M. Gabel, B. U. Gadre, S. M. Gaebel, J. R. Gair, L.
Gammaitoni, M. R. Ganija, S. G. Gaonkar, F. Garufi, S. Gaudio, G. Gaur, V.
Gayathri, N. Gehrels, G. Gemme, E. Genin, A. Gennai, D. George, J. George, L.
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Goetz, S. Gomes, G. Gonz'alez, J. M. Gonzalez Castro, A. Gopakumar, M. L.
Gorodetsky, S. E. Gossan, M. Gosselin, R. Gouaty, A. Grado, C. Graef, M.
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Grote, S. Grunewald, P. Gruning, G. M. Guidi, X. Guo, A. Gupta, M. K. Gupta,
K. E. Gushwa, E. K. Gustafson, R. Gustafson, B. R. Hall, E. D. Hall, G.
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Huerta, D. Huet, B. Hughey, S. Husa, S. H. Huttner, T. Huynh-Dinh, N. Indik,
D. R. Ingram, R. Inta, G. Intini, H. N. Isa, J.-M. Isac, M. Isi, B. R. Iyer,
K. Izumi, T. Jacqmin, K. Jani, P. Jaranowski, S. Jawahar, F.
Jim'enez-Forteza, W. W. Johnson, D. I. Jones, R. Jones, R. J. G. Jonker, L.
Ju, J. Junker, C. V. Kalaghatgi, V. Kalogera, S. Kandhasamy, G. Kang, J. B.
Kanner, S. Karki, K. S. Karvinen, M. Kasprzack, M. Katolik, E. Katsavounidis,
W. Katzman, S. Kaufer, K. Kawabe, F. K'ef'elian, D. Keitel, A. J. Kemball, R.
Kennedy, C. Kent, J. S. Key, F. Y. Khalili, I. Khan, S. Khan, Z. Khan, E. A.
Khazanov, N. Kijbunchoo, Chunglee Kim, J. C. Kim, W. Kim, W. S. Kim, Y.-M.
Kim, S. J. Kimbrell, E. J. King, P. J. King, R. Kirchhoff, J. S. Kissel, L.
Kleybolte, S. Klimenko, P. Koch, S. M. Koehlenbeck, S. Koley, V. Kondrashov,
A. Kontos, M. Korobko, W. Z. Korth, I. Kowalska, D. B. Kozak, C. Kr"amer, V.
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Kuo, A. Kutynia, S. Kwang, B. D. Lackey, K. H. Lai, M. Landry, R. N. Lang, J.
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J. D. Lough, G. Lovelace, H. L"uck, D. Lumaca, A. P. Lundgren, R. Lynch, Y.
Ma, S. Macfoy, B. Machenschalk, M. MacInnis, D. M. Macleod, I. Magana
Hernandez, F. Magana-Sandoval, L. Magana Zertuche, R. M. Magee, E. Majorana,
I. Maksimovic, N. Man, V. Mandic, V. Mangano, G. L. Mansell, M. Manske, M.
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Melatos, G. Mendell, R. A. Mercer, E. L. Merilh, M. Merzougui, S. Meshkov, C.
Messenger, C. Messick, R. Metzdorff, P. M. Meyers, F. Mezzani, H. Miao, C.
Michel, H. Middleton, E. E. Mikhailov, L. Milano, A. L. Miller, A. Miller, B.
B. Miller, J. Miller, M. Millhouse, O. Minazzoli, Y. Minenkov, J. Ming, C.
Mishra, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, A. Moggi,
M. Mohan, S. R. P. Mohapatra, M. Montani, B. C. Moore, C. J. Moore, D.
Moraru, G. Moreno, S. R. Morriss, B. Mours, C. M. Mow-Lowry, G. Mueller, A.
W. Muir, Arunava Mukherjee, D. Mukherjee, S. Mukherjee, N. Mukund, A.
Mullavey, J. Munch, E. A. M. Muniz, P. G. Murray, K. Napier, I. Nardecchia,
L. Naticchioni, R. K. Nayak, G. Nelemans, T. J. N. Nelson, M. Neri, M. Nery,
A. Neunzert, J. M. Newport, G. Newton, K. K. Y. Ng, T. T. Nguyen, D. Nichols,
A. B. Nielsen, S. Nissanke, A. Nitz, A. Noack, F. Nocera, D. Nolting, M. E.
N. Normandin, L. K. Nuttall, J. Oberling, E. Ochsner, E. Oelker, G. H. Ogin,
J. J. Oh, S. H. Oh, F. Ohme, M. Oliver, P. Oppermann, Richard J. Oram, B.
O'Reilly, R. Ormiston, L. F. Ortega, R. O'Shaughnessy, D. J. Ottaway, H.
Overmier, B. J. Owen, A. E. Pace, J. Page, M. A. Page, A. Pai, S. A. Pai, J.
R. Palamos, O. Palashov, C. Palomba, A. Pal-Singh, H. Pan, B. Pang, P. T. H.
Pang, C. Pankow, F. Pannarale, B. C. Pant, F. Paoletti, A. Paoli, M. A. Papa,
H. R. Paris, W. Parker, D. Pascucci, A. Pasqualetti, R. Passaquieti, D.
Passuello, B. Patricelli, B. L. Pearlstone, M. Pedraza, R. Pedurand, L.
Pekowsky, A. Pele, S. Penn, C. J. Perez, A. Perreca, L. M. Perri, H. P.
Pfeiffer, M. Phelps, O. J. Piccinni, M. Pichot, F. Piergiovanni, V. Pierro,
G. Pillant, L. Pinard, I. M. Pinto, M. Pitkin, R. Poggiani, P. Popolizio, E.
K. Porter, A. Post, J. Powell, J. Prasad, J. W. W. Pratt, V. Predoi, T.
Prestegard, M. Prijatelj, M. Principe, S. Privitera, R. Prix, G. A. Prodi, L.
G. Prokhorov, O. Puncken, M. Punturo, P. Puppo, M. P"urrer, H. Qi, J. Qin, S.
Qiu, V. Quetschke, E. A. Quintero, R. Quitzow-James, F. J. Raab, D. S.
Rabeling, H. Radkins, P. Raffai, S. Raja, C. Rajan, M. Rakhmanov, K. E.
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S. Reid, D. H. Reitze, H. Rew, S. D. Reyes, F. Ricci, P. M. Ricker, S.
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L. Rolland, J. G. Rollins, V. J. Roma, R. Romano, C. L. Romel, J. H. Romie,
D. Rosi'nska, M. P. Ross, S. Rowan, A. R"udiger, P. Ruggi, K. Ryan, M. Rynge,
S. Sachdev, T. Sadecki, L. Sadeghian, M. Sakellariadou, L. Salconi, M.
Saleem, F. Salemi, A. Samajdar, L. Sammut, L. M. Sampson, E. J. Sanchez, V.
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Schwalbe, J. Scott, S. M. Scott, E. Seidel, D. Sellers, A. S. Sengupta, D.
Sentenac, V. Sequino, A. Sergeev, D. A. Shaddock, T. J. Shaffer, A. A. Shah,
M. S. Shahriar, L. Shao, B. Shapiro, P. Shawhan, A. Sheperd, D. H. Shoemaker,
D. M. Shoemaker, K. Siellez, X. Siemens, M. Sieniawska, D. Sigg, A. D. Silva,
A. Singer, L. P. Singer, A. Singh, R. Singh, A. Singhal, A. M. Sintes, B. J.
J. Slagmolen, B. Smith, J. R. Smith, R. J. E. Smith, E. J. Son, J. A.
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Strigin, R. Sturani, A. L. Stuver, T. Z. Summerscales, L. Sun, S. Sunil, P.
J. Sutton, B. L. Swinkels, M. J. Szczepa'nczyk, M. Tacca, D. Talukder, D. B.
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Ugolini, C. S. Unnikrishnan, A. L. Urban, S. A. Usman, K. Vahi, H. Vahlbruch,
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Venugopalan, D. Verkindt, F. Vetrano, A. Vicer'e, A. D. Viets, S.
Vinciguerra, D. J. Vine, J.-Y. Vinet, S. Vitale, T. Vo, H. Vocca, C. Vorvick,
D. V. Voss, W. D. Vousden, S. P. Vyatchanin, A. R. Wade, L. E. Wade, M. Wade,
R. Walet, M. Walker, L. Wallace, S. Walsh, G. Wang, H. Wang, J. Z. Wang, M.
Wang, Y.-F. Wang, Y. Wang, R. L. Ward, J. Warner, M. Was, J. Watchi, B.
Weaver, L.-W. Wei, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, E. K.
Wessel, P. Wessels, T. Westphal, K. Wette, J. T. Whelan, B. F. Whiting, C.
Whittle, D. Williams, R. D. Williams, A. R. Williamson, J. L. Willis, B.
Willke, M. H. Wimmer, W. Winkler, C. C. Wipf, H. Wittel, G. Woan, J. Woehler,
J. Wofford, K. W. K. Wong, J. Worden, J. L. Wright, D. S. Wu, G. Wu, W. Yam,
H. Yamamoto, C. C. Yancey, M. J. Yap, Hang Yu, Haocun Yu, M. Yvert, A.
Zadro.zny, M. Zanolin, T. Zelenova, J.-P. Zendri, M. Zevin, L. Zhang, M.
Zhang, T. Zhang, Y.-H. Zhang, C. Zhao, M. Zhou, Z. Zhou, X. J. Zhu, M. E.
Zucker, J. Zweizig, S. Suvorova, W. Moran, R. J. Evans | Search for gravitational waves from Scorpius X-1 in the first Advanced
LIGO observing run with a hidden Markov model | null | Phys. Rev. D 95, 122003 (2017); erratum Phys. Rev. D 104, 129901
(2021) | 10.1103/PhysRevD.95.122003 | LIGO-P1700019; erratum LIGO-P2100372 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Results are presented from a semi-coherent search for continuous
gravitational waves from the brightest low-mass X-ray binary, Scorpius X-1,
using data collected during the first Advanced LIGO observing run (O1). The
search combines a frequency domain matched filter (Bessel-weighted
$\mathcal{F}$-statistic) with a hidden Markov model to track wandering of the
neutron star spin frequency. No evidence of gravitational waves is found in the
frequency range 60-650 Hz. Frequentist 95% confidence strain upper limits,
$h_0^{95\%} = 4.0\times10^{-25}$, $8.3\times10^{-25}$, and $3.0\times10^{-25}$
for electromagnetically restricted source orientation, unknown polarization,
and circular polarization, respectively, are reported at 106 Hz. They are $\leq
10$ times higher than the theoretical torque-balance limit at 106 Hz.
| [
{
"created": "Wed, 12 Apr 2017 12:09:44 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Apr 2017 10:50:54 GMT",
"version": "v2"
},
{
"created": "Wed, 31 May 2017 05:08:52 GMT",
"version": "v3"
}
] | 2023-03-01 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"Abbott",
"B. P.",
""
],
[
"Abbott",
"R.",
""
],
[
"Abbott",
"T. D.",
""
],
[
"Acernese",
"F.",
""
],
[
"Ackley",
"K.",
... | Results are presented from a semi-coherent search for continuous gravitational waves from the brightest low-mass X-ray binary, Scorpius X-1, using data collected during the first Advanced LIGO observing run (O1). The search combines a frequency domain matched filter (Bessel-weighted $\mathcal{F}$-statistic) with a hidden Markov model to track wandering of the neutron star spin frequency. No evidence of gravitational waves is found in the frequency range 60-650 Hz. Frequentist 95% confidence strain upper limits, $h_0^{95\%} = 4.0\times10^{-25}$, $8.3\times10^{-25}$, and $3.0\times10^{-25}$ for electromagnetically restricted source orientation, unknown polarization, and circular polarization, respectively, are reported at 106 Hz. They are $\leq 10$ times higher than the theoretical torque-balance limit at 106 Hz. |
2112.09832 | Takuya Katagiri | Takuya Katagiri, Masashi Kimura | The Aretakis constants and instability in general spherically symmetric
extremal black hole spacetimes: higher multipole modes, late-time tails, and
geometrical meanings | 32 pages; v2: minor revisions, accepted for publication in Phys. Rev.
D | null | 10.1103/PhysRevD.105.064062 | RUP-21-19 | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We study late-time behaviors of massive scalar fields in general static and
spherically symmetric extremal black hole spacetimes in arbitrary dimensions.
We show the existence of conserved quantities on the extremal black hole
horizons for specific mass squared and multipole modes of the scalar fields.
Those quantities on the horizon are called the Aretakis constants and are
constructed from the higher-order derivatives of the fields. Focusing on the
region near the horizon at late times, where is well approximated by the
near-horizon geometry, we show that the leading behaviors of the fields are
described by power-law tails. The late-time power-law tails lead to the
Atetakis instability: blowups of the transverse derivatives of the fields on
the horizon. We further argue that the Aretakis constants and instability
correspond to respectively constants and blowups of components of covariant
derivatives of the fields at the late time in the parallelly propagated null
geodesic frame along the horizon. We finally discuss the relation between the
Aretakis constants and ladder operators constructed from the approximate
spacetime conformal symmetry near the extremal black hole horizons.
| [
{
"created": "Sat, 18 Dec 2021 03:27:13 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Mar 2022 10:17:59 GMT",
"version": "v2"
}
] | 2022-04-13 | [
[
"Katagiri",
"Takuya",
""
],
[
"Kimura",
"Masashi",
""
]
] | We study late-time behaviors of massive scalar fields in general static and spherically symmetric extremal black hole spacetimes in arbitrary dimensions. We show the existence of conserved quantities on the extremal black hole horizons for specific mass squared and multipole modes of the scalar fields. Those quantities on the horizon are called the Aretakis constants and are constructed from the higher-order derivatives of the fields. Focusing on the region near the horizon at late times, where is well approximated by the near-horizon geometry, we show that the leading behaviors of the fields are described by power-law tails. The late-time power-law tails lead to the Atetakis instability: blowups of the transverse derivatives of the fields on the horizon. We further argue that the Aretakis constants and instability correspond to respectively constants and blowups of components of covariant derivatives of the fields at the late time in the parallelly propagated null geodesic frame along the horizon. We finally discuss the relation between the Aretakis constants and ladder operators constructed from the approximate spacetime conformal symmetry near the extremal black hole horizons. |
0705.3422 | Friedrich W. Hehl | Friedrich W. Hehl (Cologne and Missouri-Columbia) and Yu.N. Obukhov
(Cologne and Moscow) | Equivalence principle and electromagnetic field: no birefringence, no
dilaton, and no axion | 13 pages latex | Gen.Rel.Grav.40:1239-1248,2008 | 10.1007/s10714-007-0601-5 | null | gr-qc hep-th physics.class-ph | null | The coupling of the electromagnetic field to gravity is discussed. In the
premetric axiomatic approach based on the experimentally well established
conservation laws of electric charge and magnetic flux, the Maxwell equations
are the same irrespective of the presence or absence of gravity. In this sense,
one can say that the charge "substratum" and the flux "substratum" are not
influenced by the gravitational field directly. However, the interrelation
between these fundamental substrata, formalized as the {\it spacetime relation}
H=H(F) between the 2-forms of the electromagnetic excitation H and the
electromagnetic field strength F, is affected by gravity. Thus the validity of
the equivalence principle for electromagnetism depends on the form of the
spacetime relation. We discuss the nonlocal and local linear constitutive
relations and demonstrate that the spacetime metric can be accompanied also by
skewon, dilaton, and axion fields. All these premetric companions of the metric
may eventually lead to a violation of the equivalence principle.
| [
{
"created": "Wed, 23 May 2007 17:00:07 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Hehl",
"Friedrich W.",
"",
"Cologne and Missouri-Columbia"
],
[
"Obukhov",
"Yu. N.",
"",
"Cologne and Moscow"
]
] | The coupling of the electromagnetic field to gravity is discussed. In the premetric axiomatic approach based on the experimentally well established conservation laws of electric charge and magnetic flux, the Maxwell equations are the same irrespective of the presence or absence of gravity. In this sense, one can say that the charge "substratum" and the flux "substratum" are not influenced by the gravitational field directly. However, the interrelation between these fundamental substrata, formalized as the {\it spacetime relation} H=H(F) between the 2-forms of the electromagnetic excitation H and the electromagnetic field strength F, is affected by gravity. Thus the validity of the equivalence principle for electromagnetism depends on the form of the spacetime relation. We discuss the nonlocal and local linear constitutive relations and demonstrate that the spacetime metric can be accompanied also by skewon, dilaton, and axion fields. All these premetric companions of the metric may eventually lead to a violation of the equivalence principle. |
0909.5113 | Diego S\'aez-G\'omez | Olesya Gorbunova, Diego S\'aez-G\'omez | The oscillating dark energy and cosmological Casimir effect | 4 pages. Added references | Open Astron.J.3:73,2010 | 10.2174/1874381101003020073 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The role of dynamical cosmological Casimir effect to phantom (constant $w$)
and oscillating Universe is discussed. It is shown explicitly that its role is
not essential near to Big Rip singularity. However, the account of Casimir
fluid makes the scale factor approach to Rip time to be faster. Rip time itself
maybe changed too.
| [
{
"created": "Mon, 28 Sep 2009 15:17:46 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Jun 2010 11:46:40 GMT",
"version": "v2"
}
] | 2011-04-07 | [
[
"Gorbunova",
"Olesya",
""
],
[
"Sáez-Gómez",
"Diego",
""
]
] | The role of dynamical cosmological Casimir effect to phantom (constant $w$) and oscillating Universe is discussed. It is shown explicitly that its role is not essential near to Big Rip singularity. However, the account of Casimir fluid makes the scale factor approach to Rip time to be faster. Rip time itself maybe changed too. |
1203.6366 | Astrid Eichhorn | Babette D\"obrich and Astrid Eichhorn | Can we see quantum gravity? Photons in the asymptotic-safety scenario | 29 pages, 9 figures, matches journal version in JHEP | null | 10.1007/JHEP06(2012)156 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the search for a quantum theory of gravity it is crucial to find
experimental access to quantum gravitational effects. Since these are expected
to be very small at observationally accessible scales it is advantageous to
consider processes with no tree-level contribution in the Standard Model, such
as photon-photon scattering. We examine the implications of asymptotically safe
quantum gravity in a setting with extra dimensions for this case, and point out
that various near-future photon-collider setups, employing either electron or
muon colliders, or even a purely laser-based setup, could provide a first
observational window into the quantum gravity regime.
| [
{
"created": "Wed, 28 Mar 2012 20:06:42 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Jun 2012 19:35:26 GMT",
"version": "v2"
}
] | 2015-06-04 | [
[
"Döbrich",
"Babette",
""
],
[
"Eichhorn",
"Astrid",
""
]
] | In the search for a quantum theory of gravity it is crucial to find experimental access to quantum gravitational effects. Since these are expected to be very small at observationally accessible scales it is advantageous to consider processes with no tree-level contribution in the Standard Model, such as photon-photon scattering. We examine the implications of asymptotically safe quantum gravity in a setting with extra dimensions for this case, and point out that various near-future photon-collider setups, employing either electron or muon colliders, or even a purely laser-based setup, could provide a first observational window into the quantum gravity regime. |
1406.7253 | Pedro Gir\~ao | Jo\~ao L. Costa, Pedro M. Gir\~ao, Jos\'e Nat\'ario, and Jorge Drumond
Silva | On the global uniqueness for the Einstein-Maxwell-scalar field system
with a cosmological constant. Part 2: Structure of the solutions and
stability of the Cauchy horizon | 44 pages, 13 figures; v2: a few small changes; v3: a paragraph was
added in the Introduction, minor clarifications were made thoughout, the list
of references was expanded, matches final published version | null | 10.1007/s00220-015-2433-6 | null | gr-qc math-ph math.AP math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper is the second part of a trilogy dedicated to the following
problem: given spherically symmetric characteristic initial data for the
Einstein-Maxwell-scalar field system with a cosmological constant $\Lambda$,
with the data on the outgoing initial null hypersurface given by a subextremal
Reissner-Nordstrom black hole event horizon, study the future extendibility of
the corresponding maximal globally hyperbolic development as a "suitably
regular" Lorentzian manifold.
In the first paper of this sequence, we established well posedness of the
characteristic problem with general initial data.
In this second paper, we generalize the results of Dafermos on the stability
of the radius function at the Cauchy horizon by including a cosmological
constant. This requires a considerable deviation from the strategy followed by
Dafermos, focusing on the level sets of the radius function instead of the
red-shift and blue-shift regions. We also present new results on the global
structure of the solution when the free data is not identically zero in a
neighborhood of the origin.
In the third and final paper, we will consider the issue of mass inflation
and extendibility of solutions beyond the Cauchy horizon.
| [
{
"created": "Fri, 27 Jun 2014 18:04:38 GMT",
"version": "v1"
},
{
"created": "Fri, 18 Jul 2014 01:20:54 GMT",
"version": "v2"
},
{
"created": "Mon, 17 Aug 2015 17:18:49 GMT",
"version": "v3"
}
] | 2015-09-02 | [
[
"Costa",
"João L.",
""
],
[
"Girão",
"Pedro M.",
""
],
[
"Natário",
"José",
""
],
[
"Silva",
"Jorge Drumond",
""
]
] | This paper is the second part of a trilogy dedicated to the following problem: given spherically symmetric characteristic initial data for the Einstein-Maxwell-scalar field system with a cosmological constant $\Lambda$, with the data on the outgoing initial null hypersurface given by a subextremal Reissner-Nordstrom black hole event horizon, study the future extendibility of the corresponding maximal globally hyperbolic development as a "suitably regular" Lorentzian manifold. In the first paper of this sequence, we established well posedness of the characteristic problem with general initial data. In this second paper, we generalize the results of Dafermos on the stability of the radius function at the Cauchy horizon by including a cosmological constant. This requires a considerable deviation from the strategy followed by Dafermos, focusing on the level sets of the radius function instead of the red-shift and blue-shift regions. We also present new results on the global structure of the solution when the free data is not identically zero in a neighborhood of the origin. In the third and final paper, we will consider the issue of mass inflation and extendibility of solutions beyond the Cauchy horizon. |
gr-qc/0407046 | Mario La Camera | Mario La Camera | Cosmological solutions in the brane-bulk system | 14 pages, revtex4, comments added | Eur.Phys.J.C41:251-256,2005 | 10.1140/epjc/s2005-02173-5 | null | gr-qc | null | In this work we find cosmological solutions in the brane-bulk system starting
from a 5-D line element which is a simple extension, for cosmological
applications, of the pioneering Randall-Sundrum line element. From the
knowledge of the bulk metric, assumed to have the form of plane waves
propagating in the fifth dimension, we solve the corresponding 4-D Einstein
equations on the brane with a well defined energy-momentum tensor.
| [
{
"created": "Tue, 13 Jul 2004 09:55:38 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Oct 2004 17:26:55 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Nov 2004 10:49:46 GMT",
"version": "v3"
}
] | 2011-09-13 | [
[
"La Camera",
"Mario",
""
]
] | In this work we find cosmological solutions in the brane-bulk system starting from a 5-D line element which is a simple extension, for cosmological applications, of the pioneering Randall-Sundrum line element. From the knowledge of the bulk metric, assumed to have the form of plane waves propagating in the fifth dimension, we solve the corresponding 4-D Einstein equations on the brane with a well defined energy-momentum tensor. |
2203.04490 | Bekir Can L\"utf\"uo\u{g}lu | B. C. L\"utf\"uo\u{g}lu, B. Hamil and L. Dahbi | Quantum corrections to the thermodynamics of rotating charged BTZ black
hole in gravity's rainbow | 12 Figures, Typos have been fixed. Missing references and information
have been fixed | Int. J. Mod. Phys. A 37 (18) 2250126 (2022) | 10.1142/S0217751X22501263 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this manuscript, we investigate the thermal properties of the rotating
charged BTZ black hole under the gravity's rainbow (GR) and generalized
uncertainty principle (GUP) formalism. At first, we study the GR-corrected
thermal quantities according to the usual Heisenberg algebra. Then, we consider
a deformed algebra that leads to a change in the Heisenberg uncertainty
principle and compare the Hawking temperature, entropy, thermodynamical volume,
pressure, and heat capacity functions with the previous results. Thus, we
understand and interpret the quantum effects on the BTZ black hole.
| [
{
"created": "Wed, 9 Mar 2022 02:19:58 GMT",
"version": "v1"
},
{
"created": "Sun, 5 Jun 2022 11:55:56 GMT",
"version": "v2"
}
] | 2023-01-02 | [
[
"Lütfüoğlu",
"B. C.",
""
],
[
"Hamil",
"B.",
""
],
[
"Dahbi",
"L.",
""
]
] | In this manuscript, we investigate the thermal properties of the rotating charged BTZ black hole under the gravity's rainbow (GR) and generalized uncertainty principle (GUP) formalism. At first, we study the GR-corrected thermal quantities according to the usual Heisenberg algebra. Then, we consider a deformed algebra that leads to a change in the Heisenberg uncertainty principle and compare the Hawking temperature, entropy, thermodynamical volume, pressure, and heat capacity functions with the previous results. Thus, we understand and interpret the quantum effects on the BTZ black hole. |
gr-qc/9912027 | Frank Gronwald | B. Mashhoon, F. Gronwald and H.I.M. Lichtenegger | Gravitomagnetism and the Clock Effect | 27 pages, LaTeX, submitted to Proc. Bad Honnef Meeting on: GYROS,
CLOCKS, AND INTERFEROMETERS: TESTING GENERAL RELATIVITY IN SPACE (22 - 27
August 1999; Bad Honnef, Germany) | Lect.Notes Phys. 562 (2001) 83-108 | 10.1007/3-540-40988-2_5 | null | gr-qc | null | The main theoretical aspects of gravitomagnetism are reviewed. It is shown
that the gravitomagnetic precession of a gyroscope is intimately connected with
the special temporal structure around a rotating mass that is revealed by the
gravitomagnetic clock effect. This remarkable effect, which involves the
difference in the proper periods of a standard clock in prograde and retrograde
circular geodesic orbits around a rotating mass, is discussed in detail. The
implications of this effect for the notion of ``inertial dragging'' in the
general theory of relativity are presented. The theory of the clock effect is
developed within the PPN framework and the possibility of measuring it via
spaceborne clocks is examined.
| [
{
"created": "Wed, 8 Dec 1999 09:45:54 GMT",
"version": "v1"
}
] | 2016-12-07 | [
[
"Mashhoon",
"B.",
""
],
[
"Gronwald",
"F.",
""
],
[
"Lichtenegger",
"H. I. M.",
""
]
] | The main theoretical aspects of gravitomagnetism are reviewed. It is shown that the gravitomagnetic precession of a gyroscope is intimately connected with the special temporal structure around a rotating mass that is revealed by the gravitomagnetic clock effect. This remarkable effect, which involves the difference in the proper periods of a standard clock in prograde and retrograde circular geodesic orbits around a rotating mass, is discussed in detail. The implications of this effect for the notion of ``inertial dragging'' in the general theory of relativity are presented. The theory of the clock effect is developed within the PPN framework and the possibility of measuring it via spaceborne clocks is examined. |
0909.1101 | Justin Corvino | Piotr T. Chru\'sciel, Justin Corvino, James Isenberg | Construction of N-body time-symmetric initial data sets in general
relativity | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Given a collection of N asymptotically Euclidean ends with zero scalar
curvature, we construct a Riemannian manifold with zero scalar curvature and
one asymptotically Euclidean end, whose boundary has a neighborhood isometric
to the disjoint union of a specified collection of sub-regions of the given
ends. An application is the construction of time-symmetric solutions of the
constraint equations which model N-body initial data.
| [
{
"created": "Sun, 6 Sep 2009 18:41:46 GMT",
"version": "v1"
}
] | 2009-09-08 | [
[
"Chruściel",
"Piotr T.",
""
],
[
"Corvino",
"Justin",
""
],
[
"Isenberg",
"James",
""
]
] | Given a collection of N asymptotically Euclidean ends with zero scalar curvature, we construct a Riemannian manifold with zero scalar curvature and one asymptotically Euclidean end, whose boundary has a neighborhood isometric to the disjoint union of a specified collection of sub-regions of the given ends. An application is the construction of time-symmetric solutions of the constraint equations which model N-body initial data. |
1412.4672 | Davood Momeni Dr | D. Momeni, M. J. S. Houndjo, E. G\"udekli, M. E. Rodrigues, F. G.
Alvarenga, R. Myrzakulov | Spherically symmetric solutions of light Galileon | Accepted in "International Journal of Theoretical Physics" | Int.J.Theor.Phys. 55 (2016) no.2, 1211-1221 | 10.1007/s10773-015-2762-4 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have been studied the model of light Galileon with translational shift
symmetry $\phi\to \phi+c$. The matter Lagrangian is presented in the form
$\mathcal{L}_{\phi}= -\eta (\partial \phi)^2+\beta
G^{\mu\nu}\partial_{\mu}\phi\partial_{\nu}\phi$. We have been addressed two
issues: the first is that, we have been proven that, this type of Galileons
belong to the modified matter-curvature models of gravity in type of
$f(R,R^{\mu\nu}T_{\mu\nu}^m)$. Secondly, we have been investigated exact
solution for spherically symmetric geometries in this model. We have been found
an exact solution with singularity at $r=0$ in null coordinates. We have been
proven that the solution has also a non-divergence current vector norm. This
solution can be considered as an special solution which has been investigated
in literature before, in which the Galileon's field is non-static (time
dependence). Our scalar-shift symmetrized Galileon has the simple form of
$\phi=t$, which it is remembered by us dilaton field.
| [
{
"created": "Sat, 6 Dec 2014 13:45:42 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Jul 2015 14:46:44 GMT",
"version": "v2"
}
] | 2018-10-09 | [
[
"Momeni",
"D.",
""
],
[
"Houndjo",
"M. J. S.",
""
],
[
"Güdekli",
"E.",
""
],
[
"Rodrigues",
"M. E.",
""
],
[
"Alvarenga",
"F. G.",
""
],
[
"Myrzakulov",
"R.",
""
]
] | We have been studied the model of light Galileon with translational shift symmetry $\phi\to \phi+c$. The matter Lagrangian is presented in the form $\mathcal{L}_{\phi}= -\eta (\partial \phi)^2+\beta G^{\mu\nu}\partial_{\mu}\phi\partial_{\nu}\phi$. We have been addressed two issues: the first is that, we have been proven that, this type of Galileons belong to the modified matter-curvature models of gravity in type of $f(R,R^{\mu\nu}T_{\mu\nu}^m)$. Secondly, we have been investigated exact solution for spherically symmetric geometries in this model. We have been found an exact solution with singularity at $r=0$ in null coordinates. We have been proven that the solution has also a non-divergence current vector norm. This solution can be considered as an special solution which has been investigated in literature before, in which the Galileon's field is non-static (time dependence). Our scalar-shift symmetrized Galileon has the simple form of $\phi=t$, which it is remembered by us dilaton field. |
gr-qc/9610066 | Christoph Schiller | Christoph Schiller | Does matter differ from vacuum? | 23 pages, LaTeX, one postscript figure in separate file (a raw latex
sketch of the figure is available by deleting a \comment{} command in the tex
file.) | null | null | null | gr-qc | null | A structured collection of thought provoking conclusions about space and time
is given. Using only the Compton wavelength lambda = hbar / m c and the
Schwarzschild radius r_s = 2 G m / c^2, it is argued that neither the
continuity of space-time nor the concepts of space-point, instant, or point
particle have experimental backing at high energies. It is then deduced that
Lorentz, gauge, and discrete symmetries are not precisely fulfilled in nature.
In the same way, using a simple and new Gedankenexperiment, it is found that at
Planck energies, vacuum is fundamentally indistinguishable from radiation and
from matter. Some consequences for supersymmetry, duality, and unification are
presented.
| [
{
"created": "Mon, 28 Oct 1996 20:41:17 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Schiller",
"Christoph",
""
]
] | A structured collection of thought provoking conclusions about space and time is given. Using only the Compton wavelength lambda = hbar / m c and the Schwarzschild radius r_s = 2 G m / c^2, it is argued that neither the continuity of space-time nor the concepts of space-point, instant, or point particle have experimental backing at high energies. It is then deduced that Lorentz, gauge, and discrete symmetries are not precisely fulfilled in nature. In the same way, using a simple and new Gedankenexperiment, it is found that at Planck energies, vacuum is fundamentally indistinguishable from radiation and from matter. Some consequences for supersymmetry, duality, and unification are presented. |
gr-qc/0207075 | Michael Edmund Tobar | C. R. Locke, M. E. Tobar, E. N. Ivanov | Properties of a monolithic sapphire parametric transducer: prospects of
measuring the standard quantum limit | One PDF | Class.Quant.Grav.19:1877-1888,2002 | 10.1088/0264-9381/19/7/388 | null | gr-qc | null | To measure the standard quantum limit (SQL) a high quality transducer must be
coupled to a high quality mechanical system. Due to its monolithic nature, the
monolithic sapphire transducer (MST) has high quality factors for both types of
resonances. Single loop suspension is shown to yield a mechanical quality
factor of 6.10^8 at 4 K. From standard analysis we show the MST has the
potential to measure noise fluctuations of the mechanical oscillator at the
SQL. also, we point out a new way to determine if the transducer back action is
quantum limited. We show that if the fluctuations are at the quantum limit,
then the amplitude of the oscillation will be amplified by the ratio of the
ringdown time to the measurement time, which is an inherently easier
measurement.
| [
{
"created": "Fri, 19 Jul 2002 12:33:52 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Locke",
"C. R.",
""
],
[
"Tobar",
"M. E.",
""
],
[
"Ivanov",
"E. N.",
""
]
] | To measure the standard quantum limit (SQL) a high quality transducer must be coupled to a high quality mechanical system. Due to its monolithic nature, the monolithic sapphire transducer (MST) has high quality factors for both types of resonances. Single loop suspension is shown to yield a mechanical quality factor of 6.10^8 at 4 K. From standard analysis we show the MST has the potential to measure noise fluctuations of the mechanical oscillator at the SQL. also, we point out a new way to determine if the transducer back action is quantum limited. We show that if the fluctuations are at the quantum limit, then the amplitude of the oscillation will be amplified by the ratio of the ringdown time to the measurement time, which is an inherently easier measurement. |
2004.02840 | Indrani Banerjee | Subhadip Sau, Indrani Banerjee, Soumitra SenGupta | Imprints of the Janis-Newman-Winicour spacetime on observations related
to shadow and accretion | 32 pages, 4 new figures added; accepted for publication in Physical
Review D | Phys. Rev. D 102, 064027 (2020) | 10.1103/PhysRevD.102.064027 | null | gr-qc astro-ph.GA astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The final fate of gravitational collapse of massive stars has been a subject
of interest for a long time since such a collapse may lead to black holes and
naked singularities alike. Since, the formation of naked singularities is
forbidden by the cosmic censorship conjecture, exploring their observational
differences from black holes may be a possible avenue to search for these
exotic objects. The simplest possible naked singularity spacetime emerges from
the Einstein massless scalar field theory with the advantage that it smoothly
translates to the Schwarzschild solution by the variation of the scalar charge.
This background, known as the Janis-Newman-Winicour spacetime is the subject of
interest in this work. %A further advantage of working with this spacetime is
that it smoothly translates to the Schwarzschild solution by the variation of
the scalar charge. We explore electromagnetic observations around this metric
which involves investigating the characteristics of black hole accretion and
shadow. We compute the shadow radius in this spacetime and compare it with the
image of M87*, recently released by the Event Horizon Telescope Collaboration.
Similarly, we derive the expression for the luminosity from the accretion disk
and compare it with the observed optical luminosity of eleven Palomar Green
quasars. Our analysis indicates that the shadow of M87* and the quasar optical
data consistently favor the Schwarzschild background over the
Janis-Newman-Winicour spacetime. The implications of this result are discussed.
| [
{
"created": "Mon, 6 Apr 2020 17:35:13 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Sep 2020 12:28:41 GMT",
"version": "v2"
}
] | 2020-09-16 | [
[
"Sau",
"Subhadip",
""
],
[
"Banerjee",
"Indrani",
""
],
[
"SenGupta",
"Soumitra",
""
]
] | The final fate of gravitational collapse of massive stars has been a subject of interest for a long time since such a collapse may lead to black holes and naked singularities alike. Since, the formation of naked singularities is forbidden by the cosmic censorship conjecture, exploring their observational differences from black holes may be a possible avenue to search for these exotic objects. The simplest possible naked singularity spacetime emerges from the Einstein massless scalar field theory with the advantage that it smoothly translates to the Schwarzschild solution by the variation of the scalar charge. This background, known as the Janis-Newman-Winicour spacetime is the subject of interest in this work. %A further advantage of working with this spacetime is that it smoothly translates to the Schwarzschild solution by the variation of the scalar charge. We explore electromagnetic observations around this metric which involves investigating the characteristics of black hole accretion and shadow. We compute the shadow radius in this spacetime and compare it with the image of M87*, recently released by the Event Horizon Telescope Collaboration. Similarly, we derive the expression for the luminosity from the accretion disk and compare it with the observed optical luminosity of eleven Palomar Green quasars. Our analysis indicates that the shadow of M87* and the quasar optical data consistently favor the Schwarzschild background over the Janis-Newman-Winicour spacetime. The implications of this result are discussed. |
1605.06021 | Sudipto Roy | Sudipto Roy, Dibyajyoti Laha, Argho Aranya Sangma, Indrani Pal | A Study on the Expanding Universe Based on a Model of the Time Variation
of its Matter Content in the Framework of Brans-Dicke Theory | 14 pages, 8 figures | International Journal of Current Research, Volume 8, Issue 5,
pages 32251-32259, 2016 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A theoretical model of cosmic expansion has been formulated on an assumption
of inter-conversion of matter and dark energy, in the framework of Brans-Dicke
theory. An empirical scale factor has been used, which generates a signature
flip of the deceleration parameter with time. To account for the
non-conservation of matter, a function of time f(t) is incorporated into the
equation representing the density of matter. Its value at any instant of time
is proportional to the matter content of the universe. The functional form of
f(t) has been determined from the field equations by using an empirical scalar
field parameter expressed in terms of the scale factor. It is found to decrease
with time almost monotonically, implying a conversion of matter into dark
energy. Using this function f(t), the time variation of the density of matter
has been determined and also the expressions regarding the proportions of
matter and dark energy of the universe have been formulated. Time variation of
gravitational constant, its fractional rate of change and the Brans-Dicke
dimensionless parameter has been analyzed. The dependence of Brans-Dicke
parameter upon the scalar field has been determined. The present study enables
us to correlate the change of matter content with the change of deceleration
parameter and gravitational constant without using any specific mechanism of
interaction between matter and scalar field.
| [
{
"created": "Fri, 13 May 2016 20:44:13 GMT",
"version": "v1"
}
] | 2017-11-07 | [
[
"Roy",
"Sudipto",
""
],
[
"Laha",
"Dibyajyoti",
""
],
[
"Sangma",
"Argho Aranya",
""
],
[
"Pal",
"Indrani",
""
]
] | A theoretical model of cosmic expansion has been formulated on an assumption of inter-conversion of matter and dark energy, in the framework of Brans-Dicke theory. An empirical scale factor has been used, which generates a signature flip of the deceleration parameter with time. To account for the non-conservation of matter, a function of time f(t) is incorporated into the equation representing the density of matter. Its value at any instant of time is proportional to the matter content of the universe. The functional form of f(t) has been determined from the field equations by using an empirical scalar field parameter expressed in terms of the scale factor. It is found to decrease with time almost monotonically, implying a conversion of matter into dark energy. Using this function f(t), the time variation of the density of matter has been determined and also the expressions regarding the proportions of matter and dark energy of the universe have been formulated. Time variation of gravitational constant, its fractional rate of change and the Brans-Dicke dimensionless parameter has been analyzed. The dependence of Brans-Dicke parameter upon the scalar field has been determined. The present study enables us to correlate the change of matter content with the change of deceleration parameter and gravitational constant without using any specific mechanism of interaction between matter and scalar field. |
2112.10567 | Miren Radia | Miren Radia, Ulrich Sperhake, Amelia Drew, Katy Clough, Pau Figueras,
Eugene A. Lim, Justin L. Ripley, Josu C. Aurrekoetxea, Tiago Fran\c{c}a and
Thomas Helfer | Lessons for adaptive mesh refinement in numerical relativity | 46 pages, 10 figures, to match version published in CQG | Class. Quantum Grav. 39 (2022) 135006 | 10.1088/1361-6382/ac6fa9 | KCL-PH-TH/2021-89 | gr-qc astro-ph.HE hep-ph | http://creativecommons.org/licenses/by/4.0/ | We demonstrate the flexibility and utility of the Berger-Rigoutsos Adaptive
Mesh Refinement (AMR) algorithm used in the open-source numerical relativity
code GRChombo for generating gravitational waveforms from binary black-hole
inspirals, and for studying other problems involving non-trivial matter
configurations. We show that GRChombo can produce high quality binary
black-hole waveforms through a code comparison with the established numerical
relativity code Lean. We also discuss some of the technical challenges involved
in making use of full AMR (as opposed to, e.g. moving box mesh refinement),
including the numerical effects caused by using various refinement criteria
when regridding. We suggest several "rules of thumb" for when to use different
tagging criteria for simulating a variety of physical phenomena. We demonstrate
the use of these different criteria through example evolutions of a scalar
field theory. Finally, we also review the current status and general
capabilities of GRChombo.
| [
{
"created": "Mon, 20 Dec 2021 14:40:42 GMT",
"version": "v1"
},
{
"created": "Wed, 29 Dec 2021 09:36:23 GMT",
"version": "v2"
},
{
"created": "Mon, 20 Jun 2022 13:07:28 GMT",
"version": "v3"
}
] | 2022-06-22 | [
[
"Radia",
"Miren",
""
],
[
"Sperhake",
"Ulrich",
""
],
[
"Drew",
"Amelia",
""
],
[
"Clough",
"Katy",
""
],
[
"Figueras",
"Pau",
""
],
[
"Lim",
"Eugene A.",
""
],
[
"Ripley",
"Justin L.",
""
],
[
"Aur... | We demonstrate the flexibility and utility of the Berger-Rigoutsos Adaptive Mesh Refinement (AMR) algorithm used in the open-source numerical relativity code GRChombo for generating gravitational waveforms from binary black-hole inspirals, and for studying other problems involving non-trivial matter configurations. We show that GRChombo can produce high quality binary black-hole waveforms through a code comparison with the established numerical relativity code Lean. We also discuss some of the technical challenges involved in making use of full AMR (as opposed to, e.g. moving box mesh refinement), including the numerical effects caused by using various refinement criteria when regridding. We suggest several "rules of thumb" for when to use different tagging criteria for simulating a variety of physical phenomena. We demonstrate the use of these different criteria through example evolutions of a scalar field theory. Finally, we also review the current status and general capabilities of GRChombo. |
gr-qc/0202031 | Mark J. Hadley | Mark J Hadley | The orientability of spacetime | 5 Pages plus 3 figures. More explanations added as requested by
referees. Figures enhanced | Class.Quant.Grav. 19 (2002) 4565-4572 | 10.1088/0264-9381/19/17/308 | null | gr-qc quant-ph | null | Contrary to established beliefs, spacetime may not be time-orientable. By
considering an experimental test of time orientability it is shown that a
failure of time-orientability of a spacetime region would be indistinguishable
from a particle antiparticle annihilation event.
| [
{
"created": "Fri, 8 Feb 2002 20:31:57 GMT",
"version": "v1"
},
{
"created": "Sun, 10 Feb 2002 15:25:35 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Apr 2002 22:40:53 GMT",
"version": "v3"
},
{
"created": "Sun, 23 Jun 2002 17:15:56 GMT",
"version": "v4"
}
] | 2009-11-07 | [
[
"Hadley",
"Mark J",
""
]
] | Contrary to established beliefs, spacetime may not be time-orientable. By considering an experimental test of time orientability it is shown that a failure of time-orientability of a spacetime region would be indistinguishable from a particle antiparticle annihilation event. |
2110.07502 | Emmanuel Tassone | Emmanuel A. Tassone, Paula A. Mandrilli, Carlos N. Kozameh, Gonzalo D.
Quiroga, and Jos\'e I. Nieva | Numerical evolution of the center of mass and angular momentum for
binaries black holes | Pages: 12. Figures:22 | PY - 2021/10/07 VL - 104 IS - 8 | 10.1103/PhysRevD.104.084038 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The asymptotic approach derived by Kozameh-Quiroga (K-Q) provides a modern
framework to obtain the evolution of global variables of isolated sources of
gravitational radiation. We test the K-Q formalism evolving the equations of
motion for the center of mass, the intrinsic angular momentum, and several
other global variables, for black hole binary coalescence. First we evolve the
equations of motion using 777 simulations from the RIT catalogue numerical data
of $\psi_4$ [J. Healy and C.O. Lousto, Third RIT binary black hole simulations
catalog, Phys. Rev. D 102, 104018 (2020).]. We then analyze the trajectory of
the center of mass and compute the final state of other physical variables
after the coalescence has taken place. Finally, we show the results obtained
from our equations of motion are consistent with those in the Rochester
metadata.
| [
{
"created": "Thu, 14 Oct 2021 16:20:21 GMT",
"version": "v1"
}
] | 2021-10-15 | [
[
"Tassone",
"Emmanuel A.",
""
],
[
"Mandrilli",
"Paula A.",
""
],
[
"Kozameh",
"Carlos N.",
""
],
[
"Quiroga",
"Gonzalo D.",
""
],
[
"Nieva",
"José I.",
""
]
] | The asymptotic approach derived by Kozameh-Quiroga (K-Q) provides a modern framework to obtain the evolution of global variables of isolated sources of gravitational radiation. We test the K-Q formalism evolving the equations of motion for the center of mass, the intrinsic angular momentum, and several other global variables, for black hole binary coalescence. First we evolve the equations of motion using 777 simulations from the RIT catalogue numerical data of $\psi_4$ [J. Healy and C.O. Lousto, Third RIT binary black hole simulations catalog, Phys. Rev. D 102, 104018 (2020).]. We then analyze the trajectory of the center of mass and compute the final state of other physical variables after the coalescence has taken place. Finally, we show the results obtained from our equations of motion are consistent with those in the Rochester metadata. |
gr-qc/0105115 | Don Marolf | Donald Marolf | Branes, Charge and Intersections | 7 pages, no figures, latex. This brief summary of lectures given at
the Fourth Mexican School on Gravitation and Mathematical Physics was written
for the associated proceedings | Rev.Mex.Fis. 49S1 (2003) 11-13 | null | null | gr-qc | null | This is a brief summary of lectures given at the Fourth Mexican School on
Gravitation and Mathematical Physics. The lectures gave an introduction to
branes in eleven-dimensional supergravity and in type IIA supergravities in
ten-dimensions. Charge conservation and the role of the so-called `Chern-Simons
terms' were emphasized. Known exact solutions were discussed and used to
provide insight into the question `Why don't fundamental strings fall off of
D-branes,' which is often asked by relativists. The following is a brief
overview of the lectures with an associated guide to the literature.
| [
{
"created": "Wed, 30 May 2001 14:00:01 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Marolf",
"Donald",
""
]
] | This is a brief summary of lectures given at the Fourth Mexican School on Gravitation and Mathematical Physics. The lectures gave an introduction to branes in eleven-dimensional supergravity and in type IIA supergravities in ten-dimensions. Charge conservation and the role of the so-called `Chern-Simons terms' were emphasized. Known exact solutions were discussed and used to provide insight into the question `Why don't fundamental strings fall off of D-branes,' which is often asked by relativists. The following is a brief overview of the lectures with an associated guide to the literature. |
gr-qc/9306029 | Martinez | Claus Kiefer and Erik A. Martinez | On time and the quantum-to-classical transition in Jordan-Brans-Dicke
quantum gravity | 10 pages, Latex, ZU-TH 15/93, BUTP-93/15 | Class.Quant.Grav.10:2511-2518,1993 | 10.1088/0264-9381/10/12/010 | null | gr-qc astro-ph hep-th | null | Any quantum theory of gravity which treats the gravitational constant as a
dynamical variable has to address the issue of superpositions of states
corresponding to different eigenvalues. We show how the unobservability of such
superpositions can be explained through the interaction with other
gravitational degrees of freedom (decoherence). The formal framework is
canonically quantized Jordan-Brans-Dicke theory. We discuss the concepts of
intrinsic time and semiclassical time as well as the possibility of tunneling
into regions corresponding to a negative gravitational constant. We calculate
the reduced density matrix of the Jordan-Brans-Dicke field and show that the
off-diagonal elements can be sufficiently suppressed to be consistent with
experiments. The possible relevance of this mechanism for structure formation
in extended inflation is briefly discussed.
| [
{
"created": "Thu, 24 Jun 1993 12:17:44 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Kiefer",
"Claus",
""
],
[
"Martinez",
"Erik A.",
""
]
] | Any quantum theory of gravity which treats the gravitational constant as a dynamical variable has to address the issue of superpositions of states corresponding to different eigenvalues. We show how the unobservability of such superpositions can be explained through the interaction with other gravitational degrees of freedom (decoherence). The formal framework is canonically quantized Jordan-Brans-Dicke theory. We discuss the concepts of intrinsic time and semiclassical time as well as the possibility of tunneling into regions corresponding to a negative gravitational constant. We calculate the reduced density matrix of the Jordan-Brans-Dicke field and show that the off-diagonal elements can be sufficiently suppressed to be consistent with experiments. The possible relevance of this mechanism for structure formation in extended inflation is briefly discussed. |
2403.18661 | William Benoit | Ethan Marx, William Benoit, Alec Gunny, Rafia Omer, Deep Chatterjee,
Ricco C. Venterea, Lauren Wills, Muhammed Saleem, Eric Moreno, Ryan Raikman,
Ekaterina Govorkova, Dylan Rankin, Michael W. Coughlin, Philip Harris, and
Erik Katsavounidis | A machine-learning pipeline for real-time detection of gravitational
waves from compact binary coalescences | null | null | null | null | gr-qc astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | The promise of multi-messenger astronomy relies on the rapid detection of
gravitational waves at very low latencies ($\mathcal{O}$(1\,s)) in order to
maximize the amount of time available for follow-up observations. In recent
years, neural-networks have demonstrated robust non-linear modeling
capabilities and millisecond-scale inference at a comparatively small
computational footprint, making them an attractive family of algorithms in this
context. However, integration of these algorithms into the gravitational-wave
astrophysics research ecosystem has proven non-trivial. Here, we present the
first fully machine learning-based pipeline for the detection of gravitational
waves from compact binary coalescences (CBCs) running in low-latency. We
demonstrate this pipeline to have a fraction of the latency of traditional
matched filtering search pipelines while achieving state-of-the-art sensitivity
to higher-mass stellar binary black holes.
| [
{
"created": "Wed, 27 Mar 2024 15:04:15 GMT",
"version": "v1"
}
] | 2024-03-28 | [
[
"Marx",
"Ethan",
""
],
[
"Benoit",
"William",
""
],
[
"Gunny",
"Alec",
""
],
[
"Omer",
"Rafia",
""
],
[
"Chatterjee",
"Deep",
""
],
[
"Venterea",
"Ricco C.",
""
],
[
"Wills",
"Lauren",
""
],
[
"Sale... | The promise of multi-messenger astronomy relies on the rapid detection of gravitational waves at very low latencies ($\mathcal{O}$(1\,s)) in order to maximize the amount of time available for follow-up observations. In recent years, neural-networks have demonstrated robust non-linear modeling capabilities and millisecond-scale inference at a comparatively small computational footprint, making them an attractive family of algorithms in this context. However, integration of these algorithms into the gravitational-wave astrophysics research ecosystem has proven non-trivial. Here, we present the first fully machine learning-based pipeline for the detection of gravitational waves from compact binary coalescences (CBCs) running in low-latency. We demonstrate this pipeline to have a fraction of the latency of traditional matched filtering search pipelines while achieving state-of-the-art sensitivity to higher-mass stellar binary black holes. |
1809.09633 | Jose Natario | Pedro M. Gir\~ao, Jos\'e Nat\'ario, Jorge Drumond Silva | Solutions of the wave equation bounded at the Big Bang | 11 pages, 1 figure; v2: minor changes; v3: references updated,
matches final published version | Class. Quantum Grav. 36 (2019) 075016 | 10.1088/1361-6382/ab09b2 | null | gr-qc math-ph math.AP math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | By solving a singular initial value problem, we prove the existence of
solutions of the wave equation $\Box_g\phi=0$ which are bounded at the Big Bang
in the Friedmann-Lemaitre-Robertson-Walker cosmological models. More precisely,
we show that given any function $A \in H^3(\Sigma)$ (where
$\Sigma=\mathbb{R}^n, \mathbb{S}^n$ or $\mathbb{H}^n$ models the spatial
hypersurfaces) there exists a unique solution $\phi$ of the wave equation
converging to $A$ in $H^1(\Sigma)$ at the Big Bang, and whose time derivative
is suitably controlled in $L^2(\Sigma)$.
| [
{
"created": "Tue, 25 Sep 2018 18:00:11 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Feb 2019 09:31:28 GMT",
"version": "v2"
},
{
"created": "Mon, 18 Mar 2019 08:23:38 GMT",
"version": "v3"
}
] | 2019-03-19 | [
[
"Girão",
"Pedro M.",
""
],
[
"Natário",
"José",
""
],
[
"Silva",
"Jorge Drumond",
""
]
] | By solving a singular initial value problem, we prove the existence of solutions of the wave equation $\Box_g\phi=0$ which are bounded at the Big Bang in the Friedmann-Lemaitre-Robertson-Walker cosmological models. More precisely, we show that given any function $A \in H^3(\Sigma)$ (where $\Sigma=\mathbb{R}^n, \mathbb{S}^n$ or $\mathbb{H}^n$ models the spatial hypersurfaces) there exists a unique solution $\phi$ of the wave equation converging to $A$ in $H^1(\Sigma)$ at the Big Bang, and whose time derivative is suitably controlled in $L^2(\Sigma)$. |
gr-qc/0405118 | Irina Radinschi | Irina Radinschi ("Gh. Asachi" Technical University, Romania) and
I-Ching Yang (National Taitung University, Republic of China) | On the Energy of Stringy Black Holes | LaTex | New Developments in String Theory Research, ed. Susan A. Grece,
Nova Science Publishers, Inc New York, U.S.A., 2005, ISBN: 1-59454-488-3 | null | null | gr-qc | null | It is well-known that one of the most interesting and challenging problems of
General Relativity is the energy and momentum localization. There are many
attempts to evaluate the energy distribution in a general relativistic system.
One of the methods used for the energy and momentum localization is the one
which used the energy-momentum complexes. After the Einstein work, a large
number of definitions for the energy distribution was given. We mention the
expressions proposed by Landau and Lifshitz, Papapetrou, Bergmann, Weinberg and
M{\o}ller. The Einstein, Landau and Lifshitz, Papapetrou, Bergmann and Weinberg
energy-momentum complexes are restricted to calculate the energy distribution
in quasi-Cartesian coordinates. The energy-momentum complex of M{\o}ller gives
the possibility to make the calculations in any coordinate system. In this
paper we calculate the energy distribution of three stringy black hole
solutions in the M{\o}ller prescription. The M{\o}ller energy-momentum complex
gives us a consistent result for these three situations.
Keywords: M{\o}ller energy-momentum complex, charged black hole solution in
heterotic string theory PACS: 04. 20 Dw, 04. 70. Bw,
| [
{
"created": "Mon, 24 May 2004 07:48:24 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Jun 2004 07:22:21 GMT",
"version": "v2"
},
{
"created": "Mon, 14 Jun 2004 10:18:20 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Radinschi",
"Irina",
"",
"\"Gh. Asachi\" Technical University, Romania"
],
[
"Yang",
"I-Ching",
"",
"National Taitung University, Republic of China"
]
] | It is well-known that one of the most interesting and challenging problems of General Relativity is the energy and momentum localization. There are many attempts to evaluate the energy distribution in a general relativistic system. One of the methods used for the energy and momentum localization is the one which used the energy-momentum complexes. After the Einstein work, a large number of definitions for the energy distribution was given. We mention the expressions proposed by Landau and Lifshitz, Papapetrou, Bergmann, Weinberg and M{\o}ller. The Einstein, Landau and Lifshitz, Papapetrou, Bergmann and Weinberg energy-momentum complexes are restricted to calculate the energy distribution in quasi-Cartesian coordinates. The energy-momentum complex of M{\o}ller gives the possibility to make the calculations in any coordinate system. In this paper we calculate the energy distribution of three stringy black hole solutions in the M{\o}ller prescription. The M{\o}ller energy-momentum complex gives us a consistent result for these three situations. Keywords: M{\o}ller energy-momentum complex, charged black hole solution in heterotic string theory PACS: 04. 20 Dw, 04. 70. Bw, |
2003.14255 | Craig J. Hogan | Craig Hogan | Cosmological Constant in Coherent Quantum Gravity | null | null | 10.1142/S0218271820420043 | FERMILAB-PUB-20-100-A | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is argued that quantum states of geometry, like those of particles, should
be coherent on light cones of any size. An exact classical solution, the
gravitational shock wave of a relativistic point particle, is used to estimate
gravitational drag from coherent energy flows, and the expected gravitational
effect of virtual transverse vacuum energy fluctuations on surfaces of causal
diamonds. It is proposed that the appropriately spacetime-averaged
gravitational effect of the Standard Model vacuum state leads to the observed
small nonzero value of the cosmological constant, dominated by gravitational
drag of virtual gluonic strings at the strong interaction scale.
| [
{
"created": "Tue, 31 Mar 2020 14:44:15 GMT",
"version": "v1"
}
] | 2021-02-03 | [
[
"Hogan",
"Craig",
""
]
] | It is argued that quantum states of geometry, like those of particles, should be coherent on light cones of any size. An exact classical solution, the gravitational shock wave of a relativistic point particle, is used to estimate gravitational drag from coherent energy flows, and the expected gravitational effect of virtual transverse vacuum energy fluctuations on surfaces of causal diamonds. It is proposed that the appropriately spacetime-averaged gravitational effect of the Standard Model vacuum state leads to the observed small nonzero value of the cosmological constant, dominated by gravitational drag of virtual gluonic strings at the strong interaction scale. |
gr-qc/9712100 | Mr. SS Xulu | S. S. Xulu | Tolman's energy of a stringy charged black hole | 8 pages, RevTex, no figures | Int.J.Theor.Phys.37:1773-1778,1998 | 10.1023/A:1026600910525 | null | gr-qc | null | Virbhadra and Parikh studied the energy distribution associated with stringy
charged black hole in Einstein's prescription. We study the same using Tolman's
energy-momentum complex and get the same result as obtained by Virbhadra and
Parikh. The entire energy is confined inside the black hole.
| [
{
"created": "Wed, 31 Dec 1997 08:26:43 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Xulu",
"S. S.",
""
]
] | Virbhadra and Parikh studied the energy distribution associated with stringy charged black hole in Einstein's prescription. We study the same using Tolman's energy-momentum complex and get the same result as obtained by Virbhadra and Parikh. The entire energy is confined inside the black hole. |
gr-qc/9607043 | null | Fran\c{c}ois Goy | Aberration and the Question of Equivalence of some Ether Theories to
Special Relativity | 9 pages, Latex, 2 figures already included in the main file | Found. Phys. Lett. 9 No 2 (1996) 165-174 | 10.1007/BF02186259 | null | gr-qc | null | In the last two decades, theories explaining the same experiments as well as
special relativity does, were developed by using different synchronization
procedures. All of them are ether-like theories. Most authors believe these
theories to be equivalent to special relativity, but no general proof was ever
brought. By means of a Gedankenexperiment on light aberration, we produce
strong evidence that this is the case for experiments made in inertial systems.
| [
{
"created": "Sat, 20 Jul 1996 11:54:18 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Goy",
"François",
""
]
] | In the last two decades, theories explaining the same experiments as well as special relativity does, were developed by using different synchronization procedures. All of them are ether-like theories. Most authors believe these theories to be equivalent to special relativity, but no general proof was ever brought. By means of a Gedankenexperiment on light aberration, we produce strong evidence that this is the case for experiments made in inertial systems. |
2202.10801 | Fidel F. Villase\~nor | Miguel \'Angel Javaloyes, Miguel S\'anchez and Fidel F. Villase\~nor | On the significance of the stress-energy tensor in Finsler spacetimes | 40 pages. Footnotes 5 and 6 are added with respect to the published
version | Universe 2022, 8(2), 93. Special issue "Beyond Riemannian geometry
in classical and quantum gravity" | 10.3390/universe8020093 | null | gr-qc math-ph math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit the physical arguments which lead to the definition of the
stress-energy tensor $T$ in the Lorentz-Finsler setting $(M,L)$ starting at
classical Relativity. Both the standard heuristic approach using fluids and the
Lagrangian one are taken into account. In particular, we argue that the
Finslerian breaking of Lorentz symmetry makes $T$ an anisotropic 2-tensor (i.
e., a tensor for each $L$-timelike direction), in contrast with the
energy-momentum vectors defined on $M$. Such a tensor is compared with
different ones obtained by using a Lagrangian approach. The notion of
divergence is revised from a geometric viewpoint and, then, the conservation
laws of $T$ for each observer field are revisited. We introduce a natural {\em
anisotropic Lie bracket derivation}, which leads to a divergence obtained from
the volume element and the non-linear connection associated with $L$ alone. The
computation of this divergence selects the Chern anisotropic connection, thus
giving a geometric interpretation to previous choices in the literature.
| [
{
"created": "Tue, 22 Feb 2022 10:40:48 GMT",
"version": "v1"
}
] | 2022-02-23 | [
[
"Javaloyes",
"Miguel Ángel",
""
],
[
"Sánchez",
"Miguel",
""
],
[
"Villaseñor",
"Fidel F.",
""
]
] | We revisit the physical arguments which lead to the definition of the stress-energy tensor $T$ in the Lorentz-Finsler setting $(M,L)$ starting at classical Relativity. Both the standard heuristic approach using fluids and the Lagrangian one are taken into account. In particular, we argue that the Finslerian breaking of Lorentz symmetry makes $T$ an anisotropic 2-tensor (i. e., a tensor for each $L$-timelike direction), in contrast with the energy-momentum vectors defined on $M$. Such a tensor is compared with different ones obtained by using a Lagrangian approach. The notion of divergence is revised from a geometric viewpoint and, then, the conservation laws of $T$ for each observer field are revisited. We introduce a natural {\em anisotropic Lie bracket derivation}, which leads to a divergence obtained from the volume element and the non-linear connection associated with $L$ alone. The computation of this divergence selects the Chern anisotropic connection, thus giving a geometric interpretation to previous choices in the literature. |
2110.15922 | Lorena Maga\~na Zertuche | Lorena Maga\~na Zertuche, Keefe Mitman, Neev Khera, Leo C. Stein,
Michael Boyle, Nils Deppe, Fran\c{c}ois H\'ebert, Dante A. B. Iozzo, Lawrence
E. Kidder, Jordan Moxon, Harald P. Pfeiffer, Mark A. Scheel, Saul A.
Teukolsky, William Throwe, and Nils Vu | High Precision Ringdown Modeling: Multimode Fits and BMS Frames | 17 + 2 pages, 11 figures, 2 tables | Phys. Rev. D 105, 104015 (2022) | 10.1103/PhysRevD.105.104015 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quasi-normal mode (QNM) modeling is an invaluable tool for characterizing
remnant black holes, studying strong gravity, and testing GR. Only recently
have QNM studies begun to focus on multimode fitting to numerical relativity
(NR) strain waveforms. As GW observatories become even more sensitive they will
be able to resolve higher-order modes. Consequently, multimode QNM fits will be
critically important, and in turn require a more thorough treatment of the
asymptotic frame at $\mathscr{I}^+$. The first main result of this work is a
method for systematically fitting a QNM model containing many modes to a
numerical waveform produced using Cauchy-characteristic extraction (CCE), an
extraction technique which is known to resolve memory effects. We choose the
modes to model based on their power contribution to the residual between
numerical and model waveforms. We show that the all-mode strain mismatch
improves by a factor of $\sim10^5$ when using multimode fitting as opposed to
only fitting the $(2,\pm2,n)$ modes. Our most significant result addresses a
critical point that has been overlooked in the QNM literature: the importance
of matching the Bondi-van der Burg-Metzner-Sachs (BMS) frame of the numerical
waveform to that of the QNM model. We show that by mapping the numerical
waveforms$-$which exhibit the memory effect$-$to a BMS frame known as the super
rest frame, there is an improvement of $\sim10^5$ in the all-mode strain
mismatch compared to using a strain waveform whose BMS frame is not fixed.
Furthermore, we find that by mapping CCE waveforms to the super rest frame, we
can obtain all-mode mismatches that are, on average, a factor of $\sim4$ better
than using the publicly-available extrapolated waveforms. We illustrate the
effectiveness of these modeling enhancements by applying them to families of
waveforms produced by NR and comparing our results to previous QNM studies.
| [
{
"created": "Fri, 29 Oct 2021 17:16:46 GMT",
"version": "v1"
},
{
"created": "Wed, 11 May 2022 17:06:40 GMT",
"version": "v2"
}
] | 2022-05-12 | [
[
"Zertuche",
"Lorena Magaña",
""
],
[
"Mitman",
"Keefe",
""
],
[
"Khera",
"Neev",
""
],
[
"Stein",
"Leo C.",
""
],
[
"Boyle",
"Michael",
""
],
[
"Deppe",
"Nils",
""
],
[
"Hébert",
"François",
""
],
[
... | Quasi-normal mode (QNM) modeling is an invaluable tool for characterizing remnant black holes, studying strong gravity, and testing GR. Only recently have QNM studies begun to focus on multimode fitting to numerical relativity (NR) strain waveforms. As GW observatories become even more sensitive they will be able to resolve higher-order modes. Consequently, multimode QNM fits will be critically important, and in turn require a more thorough treatment of the asymptotic frame at $\mathscr{I}^+$. The first main result of this work is a method for systematically fitting a QNM model containing many modes to a numerical waveform produced using Cauchy-characteristic extraction (CCE), an extraction technique which is known to resolve memory effects. We choose the modes to model based on their power contribution to the residual between numerical and model waveforms. We show that the all-mode strain mismatch improves by a factor of $\sim10^5$ when using multimode fitting as opposed to only fitting the $(2,\pm2,n)$ modes. Our most significant result addresses a critical point that has been overlooked in the QNM literature: the importance of matching the Bondi-van der Burg-Metzner-Sachs (BMS) frame of the numerical waveform to that of the QNM model. We show that by mapping the numerical waveforms$-$which exhibit the memory effect$-$to a BMS frame known as the super rest frame, there is an improvement of $\sim10^5$ in the all-mode strain mismatch compared to using a strain waveform whose BMS frame is not fixed. Furthermore, we find that by mapping CCE waveforms to the super rest frame, we can obtain all-mode mismatches that are, on average, a factor of $\sim4$ better than using the publicly-available extrapolated waveforms. We illustrate the effectiveness of these modeling enhancements by applying them to families of waveforms produced by NR and comparing our results to previous QNM studies. |
1402.1121 | Sergey Paston | A.A. Sheykin, S.A. Paston | The approach to gravity as a theory of embedded surface | LaTeX, 10 pages. Proceedings of "II Russian-Spanish Congress Particle
and Nuclear Physics at all Scales and Cosmology", Saint-Petersburg, October
1-4, 2013 | AIP Conference Proceedings 1606, 400 (2014) | 10.1063/1.4891157 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the approach to gravity in which our curved spacetime is considered
as a surface in a flat ambient space of higher dimension (the embedding
theory). The dynamical variable in this theory is not a metric but an embedding
function. The Euler-Lagrange equations for this theory (Regge-Teitelboim
equations) are more general than the Einstein equations, and admit "extra
solutions" which do not correspond to any Einsteinian metric. The
Regge-Teitelboim equations can be explicitly analyzed for the solutions with
high symmetry. We show that symmetric embeddings of a static spherically
symmetric asymptotically flat metrics in a 6-dimensional ambient space do not
admit extra solutions of the vacuum Regge-Teitelboim equations. Therefore in
the embedding theory the solutions with such properties correspond to the
exterior Schwarzchild metric.
| [
{
"created": "Wed, 5 Feb 2014 18:34:45 GMT",
"version": "v1"
}
] | 2014-09-02 | [
[
"Sheykin",
"A. A.",
""
],
[
"Paston",
"S. A.",
""
]
] | We study the approach to gravity in which our curved spacetime is considered as a surface in a flat ambient space of higher dimension (the embedding theory). The dynamical variable in this theory is not a metric but an embedding function. The Euler-Lagrange equations for this theory (Regge-Teitelboim equations) are more general than the Einstein equations, and admit "extra solutions" which do not correspond to any Einsteinian metric. The Regge-Teitelboim equations can be explicitly analyzed for the solutions with high symmetry. We show that symmetric embeddings of a static spherically symmetric asymptotically flat metrics in a 6-dimensional ambient space do not admit extra solutions of the vacuum Regge-Teitelboim equations. Therefore in the embedding theory the solutions with such properties correspond to the exterior Schwarzchild metric. |
2009.13565 | Martin Bojowald | Martin Bojowald | Black-hole models in loop quantum gravity | 38 pages, 7 figures, published in special issue "Universe: 5th
Anniversary" | Universe 6 (2020) 125 | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Dynamical black-hole scenarios have been developed in loop quantum gravity in
various ways, combining results from mini and midisuperspace models. In the
past, the underlying geometry of space-time has often been expressed in terms
of line elements with metric components that differ from the classical
solutions of general relativity, motivated by modified equations of motion and
constraints. However, recent results have shown by explicit calculations that
most of these constructions violate general covariance and slicing
independence. The proposed line elements and black-hole models are therefore
ruled out. The only known possibility to escape this sentence is to derive not
only modified metric components but also a new space-time structure which is
covariant in a generalized sense. Formally, such a derivation is made available
by an analysis of the constraints of canonical gravity, which generate
deformations of hypersurfaces in space-time, or generalized versions if the
constraints are consistently modified. Implications for black holes are
described here. [Abbreviated abstract]
| [
{
"created": "Mon, 28 Sep 2020 18:27:10 GMT",
"version": "v1"
}
] | 2020-09-30 | [
[
"Bojowald",
"Martin",
""
]
] | Dynamical black-hole scenarios have been developed in loop quantum gravity in various ways, combining results from mini and midisuperspace models. In the past, the underlying geometry of space-time has often been expressed in terms of line elements with metric components that differ from the classical solutions of general relativity, motivated by modified equations of motion and constraints. However, recent results have shown by explicit calculations that most of these constructions violate general covariance and slicing independence. The proposed line elements and black-hole models are therefore ruled out. The only known possibility to escape this sentence is to derive not only modified metric components but also a new space-time structure which is covariant in a generalized sense. Formally, such a derivation is made available by an analysis of the constraints of canonical gravity, which generate deformations of hypersurfaces in space-time, or generalized versions if the constraints are consistently modified. Implications for black holes are described here. [Abbreviated abstract] |
1809.06054 | Marko Sossich | Petar Pavlovi\'c and Marko Sossich | The effect of vacuum polarization on the magnetic fields around a
Schwarzschild black hole | 6 pages, 2 figures | Phys. Rev. D 99, 024011 (2019) | 10.1103/PhysRevD.99.024011 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is a well known result that the effect of vacuum polarization in
gravitational fields will lead to a non-minimal coupling between gravity and
electromagnetism. We investigate this phenomenon further by considering the
description of static magnetic field around a Schwarzschild black hole. It is
found that close to the Schwarzschild horizon the magnetic fields can be
strongly modified with respect to both cases of magnetic fields on flat
spacetime and magnetic fields minimally coupled on curved spacetime. Under the
proper sign of the non-minimal coupling parameter, $q$, the effective fields
can undergo large amplifications. Furthermore, we discuss the physical meaning
of the singularities that arise in the considered problem. We conclude by
discussing the potential observational effects of vacuum polarization on the
magnetic fields. In the case of astrophysical black holes, depending on the
value of the coupling parameter, significant modifications of the magnetic near
the black hole horizons are possible -- which could be used to detect the
vacuum polarization effect or at least to put constraints on the values of the
coupling parameter. Moreover, we show how the considered effect directly
constraints the viability of primordial black holes of sizes smaller than that
of the Compton wavelength for the electron, and also impacts the distribution
of magnetic fields in the early Universe.
| [
{
"created": "Mon, 17 Sep 2018 07:44:19 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Oct 2018 12:24:05 GMT",
"version": "v2"
}
] | 2019-01-10 | [
[
"Pavlović",
"Petar",
""
],
[
"Sossich",
"Marko",
""
]
] | It is a well known result that the effect of vacuum polarization in gravitational fields will lead to a non-minimal coupling between gravity and electromagnetism. We investigate this phenomenon further by considering the description of static magnetic field around a Schwarzschild black hole. It is found that close to the Schwarzschild horizon the magnetic fields can be strongly modified with respect to both cases of magnetic fields on flat spacetime and magnetic fields minimally coupled on curved spacetime. Under the proper sign of the non-minimal coupling parameter, $q$, the effective fields can undergo large amplifications. Furthermore, we discuss the physical meaning of the singularities that arise in the considered problem. We conclude by discussing the potential observational effects of vacuum polarization on the magnetic fields. In the case of astrophysical black holes, depending on the value of the coupling parameter, significant modifications of the magnetic near the black hole horizons are possible -- which could be used to detect the vacuum polarization effect or at least to put constraints on the values of the coupling parameter. Moreover, we show how the considered effect directly constraints the viability of primordial black holes of sizes smaller than that of the Compton wavelength for the electron, and also impacts the distribution of magnetic fields in the early Universe. |
2005.03859 | Katsuki Aoki | Katsuki Aoki, Mohammad Ali Gorji, and Shinji Mukohyama | A consistent theory of $D\rightarrow 4$ Einstein-Gauss-Bonnet gravity | 8 pages, no figures, published version | null | 10.1016/j.physletb.2020.135843 | YITP-20-66, IPMU20-0050 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the $D\rightarrow 4$ limit of the $D$-dimensional
Einstein-Gauss-Bonnet gravity, where the limit is taken with
$\tilde{\alpha}=(D-4)\, \alpha$ kept fixed and $\alpha$ is the original
Gauss-Bonnet coupling. Using the ADM decomposition in $D$ dimensions, we
clarify that the limit is rather subtle and ambiguous (if not ill-defined) and
depends on the way how to regularize the Hamiltonian or/and the equations of
motion. To find a consistent theory in $4$ dimensions that is different from
general relativity, the regularization needs to either break (a part of) the
diffeomorphism invariance or lead to an extra degree of freedom, in agreement
with the Lovelock theorem. We then propose a consistent theory of $D\rightarrow
4$ Einstein-Gauss-Bonnet gravity with two dynamical degrees of freedom by
breaking the temporal diffeomorphism invariance and argue that, under a number
of reasonable assumptions, the theory is unique up to a choice of a constraint
that stems from a temporal gauge condition.
| [
{
"created": "Fri, 8 May 2020 05:14:37 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Jun 2020 01:33:40 GMT",
"version": "v2"
},
{
"created": "Fri, 9 Oct 2020 02:37:42 GMT",
"version": "v3"
}
] | 2020-10-12 | [
[
"Aoki",
"Katsuki",
""
],
[
"Gorji",
"Mohammad Ali",
""
],
[
"Mukohyama",
"Shinji",
""
]
] | We investigate the $D\rightarrow 4$ limit of the $D$-dimensional Einstein-Gauss-Bonnet gravity, where the limit is taken with $\tilde{\alpha}=(D-4)\, \alpha$ kept fixed and $\alpha$ is the original Gauss-Bonnet coupling. Using the ADM decomposition in $D$ dimensions, we clarify that the limit is rather subtle and ambiguous (if not ill-defined) and depends on the way how to regularize the Hamiltonian or/and the equations of motion. To find a consistent theory in $4$ dimensions that is different from general relativity, the regularization needs to either break (a part of) the diffeomorphism invariance or lead to an extra degree of freedom, in agreement with the Lovelock theorem. We then propose a consistent theory of $D\rightarrow 4$ Einstein-Gauss-Bonnet gravity with two dynamical degrees of freedom by breaking the temporal diffeomorphism invariance and argue that, under a number of reasonable assumptions, the theory is unique up to a choice of a constraint that stems from a temporal gauge condition. |
2108.06989 | Pramit Rej | Piyali Bhar and Pramit Rej | Stable and self consistent charged gravastar model within the framework
of $f(R,\,T)$ gravity | 23 Pages, 10 Figures, Accepted for publication in European Physical
Journal C on 12.08.2021 | Eur. Phys. J. C 81, 763 (2021) | 10.1140/epjc/s10052-021-09548-0 | null | gr-qc astro-ph.GA astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we discuss the configuration of a gravastar (gravitational
vacuum stars) in the context of $f(R, \,T )$ gravity by employing the
Mazur-Mottola conjecture [P. Mazur and E. Mottola, Report No. LA-UR-01-5067; P.
Mazur and E. Mottola, Proc. Natl. Acad. Sci. USA $101$, $9545$ ($2004$)].
Gravastar is conceptually a substitute for a black hole theory as available in
literature and it has three regions with different equation of states. By
assuming that the gravastar geometry admits conformal killing vector, the
Einstein-Maxwell field equations have been solved in different regions of
gravastar by taking a specific equation of state as proposed by Mazur and
Mottola. We match our interior spacetime to the exterior spherical region which
is completely vacuum and described by Reissner-Nordstr\"{o}m geometry. For a
particular choice of $f(R,\,T)$ as $f(R, \,T )=R+2\gamma T$, here we analyze
various physical properties of the thin shell and also presented our results
graphically for these properties. The stability analysis of our present model
is also studied by introducing a new parameter $\eta$ and we explored the
stability regions. Our proposed gravastar model in presence of charge might be
treated as a successful stable alternative of the charged black hole in the
context of this gravity.
| [
{
"created": "Mon, 16 Aug 2021 09:37:21 GMT",
"version": "v1"
}
] | 2021-08-26 | [
[
"Bhar",
"Piyali",
""
],
[
"Rej",
"Pramit",
""
]
] | In this work, we discuss the configuration of a gravastar (gravitational vacuum stars) in the context of $f(R, \,T )$ gravity by employing the Mazur-Mottola conjecture [P. Mazur and E. Mottola, Report No. LA-UR-01-5067; P. Mazur and E. Mottola, Proc. Natl. Acad. Sci. USA $101$, $9545$ ($2004$)]. Gravastar is conceptually a substitute for a black hole theory as available in literature and it has three regions with different equation of states. By assuming that the gravastar geometry admits conformal killing vector, the Einstein-Maxwell field equations have been solved in different regions of gravastar by taking a specific equation of state as proposed by Mazur and Mottola. We match our interior spacetime to the exterior spherical region which is completely vacuum and described by Reissner-Nordstr\"{o}m geometry. For a particular choice of $f(R,\,T)$ as $f(R, \,T )=R+2\gamma T$, here we analyze various physical properties of the thin shell and also presented our results graphically for these properties. The stability analysis of our present model is also studied by introducing a new parameter $\eta$ and we explored the stability regions. Our proposed gravastar model in presence of charge might be treated as a successful stable alternative of the charged black hole in the context of this gravity. |
2001.00863 | Daniela P\'erez | Daniela P\'erez, Gustavo E. Romero | Astrophysical Constraints on Strong Modified Gravity | In: Topics on Strong Gravity: A Modern View on Theories and
Experiments. C\'esar Augusto Zen Vasconcellos (Ed.). World Scientific, 2020,
pp. 19-65 | null | 10.1142/11186 | null | gr-qc astro-ph.CO astro-ph.GA astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We offer a discussion on the strong field regime predictions of two families
of theories that deviate from General Relativity in different aspects:
$f(R)$-gravity and Scalar-Tensor-Vector Gravity (STVG). We discuss
astrophysical effects in models based upon both matter and vacuum solutions of
such theories. In particular, we analize neutron star structure and the
constraints on the parameters of the theories introduced by the latest
observations. We also review black hole solutions and several astrophysical
consequences of them, including accretion disks and jets. Finally, we report on
the implications of the detection of various gravitational wave events for
these theories.
| [
{
"created": "Fri, 3 Jan 2020 15:38:42 GMT",
"version": "v1"
}
] | 2020-01-06 | [
[
"Pérez",
"Daniela",
""
],
[
"Romero",
"Gustavo E.",
""
]
] | We offer a discussion on the strong field regime predictions of two families of theories that deviate from General Relativity in different aspects: $f(R)$-gravity and Scalar-Tensor-Vector Gravity (STVG). We discuss astrophysical effects in models based upon both matter and vacuum solutions of such theories. In particular, we analize neutron star structure and the constraints on the parameters of the theories introduced by the latest observations. We also review black hole solutions and several astrophysical consequences of them, including accretion disks and jets. Finally, we report on the implications of the detection of various gravitational wave events for these theories. |
gr-qc/9902077 | Alfredo Macias | Eckehard W. Mielke, Alfredo Macias (UAM-Iztapalapa) | Chiral supergravity and anomalies | Plain Latex 25 pages, no figures. to appear in Annalen der Physik
(Leipzig) 1999 | Annalen Phys. 8 (1999) 301-317 | 10.1002/(SICI)1521-3889(199904)8:4<301::AID-ANDP301>3.0.CO;2-2 | UAM-I 9902028 | gr-qc | null | Similarily as in the Ashtekar approach, the translational Chern-Simons term
is, as a generating function, instrumental for a chiral reformulation of simple
(N=1) supergravity. After applying the algebraic Cartan relation between spin
and torsion, the resulting canonical transformation induces not only
decomposition of the gravitational fields into selfdual and antiselfdual modes,
but also a splitting of the Rarita-Schwinger fields into their chiral parts in
a natural way. In some detail, we also analyze the consequences for axial and
chiral anomalies.
| [
{
"created": "Wed, 24 Feb 1999 00:55:18 GMT",
"version": "v1"
}
] | 2017-09-27 | [
[
"Mielke",
"Eckehard W.",
"",
"UAM-Iztapalapa"
],
[
"Macias",
"Alfredo",
"",
"UAM-Iztapalapa"
]
] | Similarily as in the Ashtekar approach, the translational Chern-Simons term is, as a generating function, instrumental for a chiral reformulation of simple (N=1) supergravity. After applying the algebraic Cartan relation between spin and torsion, the resulting canonical transformation induces not only decomposition of the gravitational fields into selfdual and antiselfdual modes, but also a splitting of the Rarita-Schwinger fields into their chiral parts in a natural way. In some detail, we also analyze the consequences for axial and chiral anomalies. |
2403.15867 | Adnan Malik | Adnan Malik, Aimen Rauf, Kazuharu Bamba, M. Farasat Shamir | Change of the sign of the Hubble parameter and its stability in
higher-order torsion gravity | 21 pages, 22 figures, Submitted for publication | null | null | FU-PCG-134 | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We explore the change in the sign of the Hubble parameter in the early
universe and its stability in higher-order torsion gravity. Our study explores
the various scenarios involving the sub-relativistic universe, radiation
universe, ultra-relativistic universe, dust universe, and stiff fluid universe.
Different analytical methods, including power-law, exponential scalar factor,
and hybrid scale factor methods, are employed to examine the behavior of the
universe about the equation of state (EoS) parameters. This study is based on
the previous ones by presenting a more comprehensive analysis of the bouncing
scenarios within the higher-order torsion gravity framework. It makes
significant progress in reconstructing gravitational Lagrangians, which are
tailored to specific parameter values, allowing for a thorough examination of
the energy conditions necessary for successful bouncing models. These derived
Lagrangians provide analytical solutions for a range of bouncing models,
including symmetric bounce, super-bounce, oscillatory bounce, matter bounce,
and exponential bouncing settings. The presence of exotic matter is responsible
for the accelerated expansion of the universe, as it exhibits substantial
negative pressure. A thorough analysis of torsion-based gravity theories and
the specific investigations into bouncing scenarios set it apart from previous
works exploring alternative gravity theories and their cosmological
consequences. These contributions lie in the comprehensive exploration of
bouncing models and the detailed examination of the energy conditions in
higher-order torsion gravity.
| [
{
"created": "Sat, 23 Mar 2024 15:31:12 GMT",
"version": "v1"
}
] | 2024-03-26 | [
[
"Malik",
"Adnan",
""
],
[
"Rauf",
"Aimen",
""
],
[
"Bamba",
"Kazuharu",
""
],
[
"Shamir",
"M. Farasat",
""
]
] | We explore the change in the sign of the Hubble parameter in the early universe and its stability in higher-order torsion gravity. Our study explores the various scenarios involving the sub-relativistic universe, radiation universe, ultra-relativistic universe, dust universe, and stiff fluid universe. Different analytical methods, including power-law, exponential scalar factor, and hybrid scale factor methods, are employed to examine the behavior of the universe about the equation of state (EoS) parameters. This study is based on the previous ones by presenting a more comprehensive analysis of the bouncing scenarios within the higher-order torsion gravity framework. It makes significant progress in reconstructing gravitational Lagrangians, which are tailored to specific parameter values, allowing for a thorough examination of the energy conditions necessary for successful bouncing models. These derived Lagrangians provide analytical solutions for a range of bouncing models, including symmetric bounce, super-bounce, oscillatory bounce, matter bounce, and exponential bouncing settings. The presence of exotic matter is responsible for the accelerated expansion of the universe, as it exhibits substantial negative pressure. A thorough analysis of torsion-based gravity theories and the specific investigations into bouncing scenarios set it apart from previous works exploring alternative gravity theories and their cosmological consequences. These contributions lie in the comprehensive exploration of bouncing models and the detailed examination of the energy conditions in higher-order torsion gravity. |
2304.07761 | Anshuman Baruah | Anshuman Baruah and Ali \"Ovg\"un and Atri Deshamukhya | Quasinormal Modes and Bounding Greybody Factors of GUP-corrected Black
Holes in Kalb-Ramond Gravity | null | Annals of Physics 455, 169393 (2023) | 10.1016/j.aop.2023.169393 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The vacuum expectation value of the non-minimally coupled Kalb-Ramond (KR)
field leads to spontaneous local Lorentz symmetry violation, and static
spherically symmetric solutions exist. In this study, we study the quasinormal
modes (QNMs) of modified black holes in non--minimally coupled KR gravity. We
employ a higher-order Pad\'e averaged WKB method to compute the QNMs for
scalar, electromagnetic, and gravitational perturbations. In order to account
for quantum corrections, we examine the geometric characteristics of the
horizon and QNMs by introducing the generalized uncertainty principle (GUP).
Additionally, we shed light on the impact of the Lorentz violating parameters
on our findings and estimate QNMs for different perturbations. Further, we
estimate bounds on the greybody factors for the modified and GUP-corrected
black holes. Our findings reveal the influence of the Lorentz violating
parameters in the model on the QNM frequencies and their reliance on the GUP
parameters.
| [
{
"created": "Sun, 16 Apr 2023 12:26:05 GMT",
"version": "v1"
},
{
"created": "Sat, 24 Jun 2023 16:57:05 GMT",
"version": "v2"
}
] | 2023-06-27 | [
[
"Baruah",
"Anshuman",
""
],
[
"Övgün",
"Ali",
""
],
[
"Deshamukhya",
"Atri",
""
]
] | The vacuum expectation value of the non-minimally coupled Kalb-Ramond (KR) field leads to spontaneous local Lorentz symmetry violation, and static spherically symmetric solutions exist. In this study, we study the quasinormal modes (QNMs) of modified black holes in non--minimally coupled KR gravity. We employ a higher-order Pad\'e averaged WKB method to compute the QNMs for scalar, electromagnetic, and gravitational perturbations. In order to account for quantum corrections, we examine the geometric characteristics of the horizon and QNMs by introducing the generalized uncertainty principle (GUP). Additionally, we shed light on the impact of the Lorentz violating parameters on our findings and estimate QNMs for different perturbations. Further, we estimate bounds on the greybody factors for the modified and GUP-corrected black holes. Our findings reveal the influence of the Lorentz violating parameters in the model on the QNM frequencies and their reliance on the GUP parameters. |
gr-qc/0107081 | Patrice Hello | Nicolas Arnaud, Matteo Barsuglia, Marie-Anne Bizouard, Philippe
Canitrot, Fabien Cavalier, Michel Davier, Patrice Hello and Thierry Pradier | Detection in coincidence of gravitational wave bursts with a network of
interferometric detectors (I): Geometric acceptance and timing | low resolution figure 1 due to file size problems | Phys.Rev. D65 (2002) 042004 | 10.1103/PhysRevD.65.042004 | null | gr-qc | null | Detecting gravitational wave bursts (characterised by short durations and
poorly modelled waveforms) requires to have coincidences between several
interferometric detectors in order to reject non-stationary noise events. As
the wave amplitude seen in a detector depends on its location with respect to
the source direction and as the signal to noise ratio of these bursts are
expected to be low, coincidences between antennas may not be so likely. This
paper investigates this question from a statistical point of view by using a
simple model of a network of detectors; it also estimates the timing precision
of a detection in an interferometer which is an important issue for the
reconstruction of the source location, based on time delays.
| [
{
"created": "Wed, 25 Jul 2001 09:25:26 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Arnaud",
"Nicolas",
""
],
[
"Barsuglia",
"Matteo",
""
],
[
"Bizouard",
"Marie-Anne",
""
],
[
"Canitrot",
"Philippe",
""
],
[
"Cavalier",
"Fabien",
""
],
[
"Davier",
"Michel",
""
],
[
"Hello",
"Patrice",
""... | Detecting gravitational wave bursts (characterised by short durations and poorly modelled waveforms) requires to have coincidences between several interferometric detectors in order to reject non-stationary noise events. As the wave amplitude seen in a detector depends on its location with respect to the source direction and as the signal to noise ratio of these bursts are expected to be low, coincidences between antennas may not be so likely. This paper investigates this question from a statistical point of view by using a simple model of a network of detectors; it also estimates the timing precision of a detection in an interferometer which is an important issue for the reconstruction of the source location, based on time delays. |
1909.09452 | Sergey Yu. Vernov | Emilio Elizalde, Ekaterina O. Pozdeeva, Sergey Yu. Vernov | Reconstruction Procedure for Nonlocal Gauss-Bonnet Models | 5 pages | Int. J. Mod. Phys. A 35 (2020) 2040045 | 10.1142/S0217751X2040045X | null | gr-qc astro-ph.CO math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the cosmological dynamics of nonlocally corrected gravity
involving a function of the inverse d'Alembertian acting on the Gauss-Bonnet
term. Casting the dynamical equations in local form, we derive the
reconstruction procedure. We find conditions on the model parameters that are
sufficient for the existence of de Sitter solutions and obtain these solutions
explicitly.
| [
{
"created": "Fri, 20 Sep 2019 12:27:02 GMT",
"version": "v1"
}
] | 2020-03-12 | [
[
"Elizalde",
"Emilio",
""
],
[
"Pozdeeva",
"Ekaterina O.",
""
],
[
"Vernov",
"Sergey Yu.",
""
]
] | We investigate the cosmological dynamics of nonlocally corrected gravity involving a function of the inverse d'Alembertian acting on the Gauss-Bonnet term. Casting the dynamical equations in local form, we derive the reconstruction procedure. We find conditions on the model parameters that are sufficient for the existence of de Sitter solutions and obtain these solutions explicitly. |
1609.02038 | Saurya Das | Saurya Das, Gabor Kunstatter | The central role of symmetry in physics | Invited review article for the Journal of Applied and Fundamental
Sciences (Assam Don Bosco University, India). Minor changes. References added | Journal of Applied and Fundamental Sciences (Assam Don Bosco
University, India), Vol.2(2), 69-77 (2016) | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spacetime and internal symmetries can be used to severely restrict the form
of the equations for the fundamental laws of physics. The success of this
approach in the context of general relativity and particle physics motivates
the conjecture that symmetries may help us to one day uncover the ultimate
theory that provides a unique, unified description of all observed physical
phenomena. We examine some of the strengths and weaknesses of this conjecture.
| [
{
"created": "Tue, 6 Sep 2016 05:38:48 GMT",
"version": "v1"
},
{
"created": "Sun, 11 Sep 2016 18:37:22 GMT",
"version": "v2"
}
] | 2017-02-16 | [
[
"Das",
"Saurya",
""
],
[
"Kunstatter",
"Gabor",
""
]
] | Spacetime and internal symmetries can be used to severely restrict the form of the equations for the fundamental laws of physics. The success of this approach in the context of general relativity and particle physics motivates the conjecture that symmetries may help us to one day uncover the ultimate theory that provides a unique, unified description of all observed physical phenomena. We examine some of the strengths and weaknesses of this conjecture. |
1404.3273 | Supriya Pan | Supriya Pan and Subenoy Chakraborty | Will there be future deceleration? A study of particle creation
mechanism in non-equilibrium thermodynamics | 12 pages, 12 figures, More discussions added, references updated | Adv.High Energy Phys. 2015 (2015) 654025 | 10.1155/2015/654025 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The paper deals with non-equilibrium thermodynamics based on adiabatic
particle creation mechanism with the motivation of considering it as an
alternative choice to explain the recent observed accelerating phase of the
universe. Using Friedmann equations, it is shown that the deceleration
parameter ($q$) can be obtained from the knowledge of the particle production
rate ($\Gamma$). Motivated from thermodynamical point of view, cosmological
solutions are evaluated for the particle creation rates in three cosmic phases,
namely, inflation, matter dominated and present late time acceleration. The
deceleration parameter ($q$) is expressed as a function of the redshift
parameter ($z$), and its variation is presented graphically. Also, statefinder
analysis has been presented graphically in three different phases of the
universe. Finally, two non-interacting fluids with different particle creation
rates are considered as cosmic substratum, and deceleration parameter ($q$) is
evaluated. It is examined whether more than one transition of $q$ is possible
or not by graphical representations.
| [
{
"created": "Sat, 12 Apr 2014 09:59:17 GMT",
"version": "v1"
},
{
"created": "Sun, 12 Apr 2015 06:48:31 GMT",
"version": "v2"
}
] | 2015-04-14 | [
[
"Pan",
"Supriya",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | The paper deals with non-equilibrium thermodynamics based on adiabatic particle creation mechanism with the motivation of considering it as an alternative choice to explain the recent observed accelerating phase of the universe. Using Friedmann equations, it is shown that the deceleration parameter ($q$) can be obtained from the knowledge of the particle production rate ($\Gamma$). Motivated from thermodynamical point of view, cosmological solutions are evaluated for the particle creation rates in three cosmic phases, namely, inflation, matter dominated and present late time acceleration. The deceleration parameter ($q$) is expressed as a function of the redshift parameter ($z$), and its variation is presented graphically. Also, statefinder analysis has been presented graphically in three different phases of the universe. Finally, two non-interacting fluids with different particle creation rates are considered as cosmic substratum, and deceleration parameter ($q$) is evaluated. It is examined whether more than one transition of $q$ is possible or not by graphical representations. |
2011.08715 | Jakub K\'aninsk\'y | Jakub K\'aninsk\'y | Models of Discrete Linear Evolution for Quantum Systems | 47 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Discrete canonical evolution is a key tool for understanding the dynamics in
discrete models of spacetime, in particular those represented by a triangular
Regge lattice. We consider a finite-dimensional system whose evolution is
realized by a series of discrete-time evolution steps governed by Hamiltonian
equations of motion that are linear in the canonical coordinates. The evolution
is allowed to be irregular, which produces constraints as well as
non-uniqueness of solutions. We provide two independent and fundamentally
different approaches to canonical quantization of this system, including
detailed description of the evolution maps, measurement and path integrals. It
is argued that some irregular discrete systems may be most naturally described
by a non-unitary quantum evolution. The formalism is then applied to a simple
yet physically relevant model of massless scalar field on a two-dimensional
spacetime lattice.
| [
{
"created": "Tue, 17 Nov 2020 15:41:42 GMT",
"version": "v1"
}
] | 2020-11-18 | [
[
"Káninský",
"Jakub",
""
]
] | Discrete canonical evolution is a key tool for understanding the dynamics in discrete models of spacetime, in particular those represented by a triangular Regge lattice. We consider a finite-dimensional system whose evolution is realized by a series of discrete-time evolution steps governed by Hamiltonian equations of motion that are linear in the canonical coordinates. The evolution is allowed to be irregular, which produces constraints as well as non-uniqueness of solutions. We provide two independent and fundamentally different approaches to canonical quantization of this system, including detailed description of the evolution maps, measurement and path integrals. It is argued that some irregular discrete systems may be most naturally described by a non-unitary quantum evolution. The formalism is then applied to a simple yet physically relevant model of massless scalar field on a two-dimensional spacetime lattice. |
gr-qc/0204077 | Giovanni Amelino-Camelia | Giovanni Amelino-Camelia, Y.Jack NG, Hendrik Van Dam | Anomalous particle-production thresholds through systematic and
non-systematic quantum-gravity effects | 10 pages, LaTex | Astropart.Phys.19:729-738,2003 | 10.1016/S0927-6505(03)00136-1 | null | gr-qc | null | A growing number of studies is being devoted to the identification of
plausible quantum properties of spacetime which might give rise to observably
large effects. The literature on this subject is now relatively large,
including studies in string theory, loop quantum gravity and noncommutative
geometry. It is useful to divide the various proposals into proposals involving
a systematic quantum-gravity effect (an effect that would shift the
main/average prediction for a given observable quantity) and proposals
involving a non-systematic quantum-gravity effect (an effect that would
introduce new fundamental uncertanties in some observable quantity). The case
of quantum-gravity-induced particle-production-threshold anomalies, a much
studied example of potentially observable quantum-gravity effect, is here used
as an example to illustrate the differences to be expected between systematic
and non-systematic effects.
| [
{
"created": "Wed, 24 Apr 2002 17:43:53 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Amelino-Camelia",
"Giovanni",
""
],
[
"NG",
"Y. Jack",
""
],
[
"Van Dam",
"Hendrik",
""
]
] | A growing number of studies is being devoted to the identification of plausible quantum properties of spacetime which might give rise to observably large effects. The literature on this subject is now relatively large, including studies in string theory, loop quantum gravity and noncommutative geometry. It is useful to divide the various proposals into proposals involving a systematic quantum-gravity effect (an effect that would shift the main/average prediction for a given observable quantity) and proposals involving a non-systematic quantum-gravity effect (an effect that would introduce new fundamental uncertanties in some observable quantity). The case of quantum-gravity-induced particle-production-threshold anomalies, a much studied example of potentially observable quantum-gravity effect, is here used as an example to illustrate the differences to be expected between systematic and non-systematic effects. |
gr-qc/0408054 | Mauricio Bellini | Jose Edgar Madriz Aguilar (IFM, UMSNH) and Mauricio Bellini (Mar del
Plata University & CONICET) | Extra force and extra mass from noncompact Kaluza-Klein theory in a
cosmological model | final version to be published in EPJC | Eur.Phys.J.C42:349,2005 | 10.1140/epjc/s2005-02295-8 | null | gr-qc astro-ph hep-ph hep-th | null | Using the Hamilton-Jacobi formalism, we study extra force and extra mass in a
recently introduced noncompact Kaluza-Klein cosmological model. We examine the
inertial 4D mass $m_0$ of the inflaton field on a 4D FRW bulk in two examples.
We find that $m_0$ has a geometrical origin and antigravitational effects on a
non inertial 4D bulk should be a consequence of the motion of the fifth
coordinate with respect to the 4D bulk.
| [
{
"created": "Tue, 17 Aug 2004 18:31:27 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Sep 2004 19:41:50 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Feb 2005 22:56:05 GMT",
"version": "v3"
},
{
"created": "Fri, 13 May 2005 14:07:51 GMT",
"version": "v4"
},
{
"c... | 2008-11-26 | [
[
"Aguilar",
"Jose Edgar Madriz",
"",
"IFM, UMSNH"
],
[
"Bellini",
"Mauricio",
"",
"Mar del\n Plata University & CONICET"
]
] | Using the Hamilton-Jacobi formalism, we study extra force and extra mass in a recently introduced noncompact Kaluza-Klein cosmological model. We examine the inertial 4D mass $m_0$ of the inflaton field on a 4D FRW bulk in two examples. We find that $m_0$ has a geometrical origin and antigravitational effects on a non inertial 4D bulk should be a consequence of the motion of the fifth coordinate with respect to the 4D bulk. |
gr-qc/0610056 | Mike Berger | Jang Young Bang and Micheal S. Berger | Quantum Mechanics and the Generalized Uncertainty Principle | 8 pages, 3 figures (added references) | Phys.Rev.D74:125012,2006 | 10.1103/PhysRevD.74.125012 | IUHET-501 | gr-qc | null | The generalized uncertainty principle has been described as a general
consequence of incorporating a minimal length from a theory of quantum gravity.
We consider a simple quantum mechanical model where the operator corresponding
to position has discrete eigenvalues and show how the generalized uncertainty
principle results for minimum uncertainty wave packets.
| [
{
"created": "Wed, 11 Oct 2006 15:36:09 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Nov 2006 19:00:28 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Bang",
"Jang Young",
""
],
[
"Berger",
"Micheal S.",
""
]
] | The generalized uncertainty principle has been described as a general consequence of incorporating a minimal length from a theory of quantum gravity. We consider a simple quantum mechanical model where the operator corresponding to position has discrete eigenvalues and show how the generalized uncertainty principle results for minimum uncertainty wave packets. |
1107.1092 | Jorma Louko | Jorma Louko, Eric Martinez-Pascual | Constraint rescaling in refined algebraic quantisation: momentum
constraint | 26 pages. v2: minor clarifications and corrections | J. Math. Phys. 52, 123504 (2011) | 10.1063/1.3664336 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate refined algebraic quantisation within a family of classically
equivalent constrained Hamiltonian systems that are related to each other by
rescaling a momentum-type constraint. The quantum constraint is implemented by
a rigging map that is motivated by group averaging but has a resolution finer
than what can be peeled off from the formally divergent contributions to the
averaging integral. Three cases emerge, depending on the asymptotics of the
rescaling function: (i) quantisation is equivalent to that with identity
scaling; (ii) quantisation fails, owing to nonexistence of self-adjoint
extensions of the constraint operator; (iii) a quantisation ambiguity arises
from the self-adjoint extension of the constraint operator, and the resolution
of this purely quantum mechanical ambiguity determines the superselection
structure of the physical Hilbert space. Prospects of generalising the analysis
to systems with several constraints are discussed.
| [
{
"created": "Wed, 6 Jul 2011 10:54:36 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Dec 2011 18:57:55 GMT",
"version": "v2"
}
] | 2011-12-08 | [
[
"Louko",
"Jorma",
""
],
[
"Martinez-Pascual",
"Eric",
""
]
] | We investigate refined algebraic quantisation within a family of classically equivalent constrained Hamiltonian systems that are related to each other by rescaling a momentum-type constraint. The quantum constraint is implemented by a rigging map that is motivated by group averaging but has a resolution finer than what can be peeled off from the formally divergent contributions to the averaging integral. Three cases emerge, depending on the asymptotics of the rescaling function: (i) quantisation is equivalent to that with identity scaling; (ii) quantisation fails, owing to nonexistence of self-adjoint extensions of the constraint operator; (iii) a quantisation ambiguity arises from the self-adjoint extension of the constraint operator, and the resolution of this purely quantum mechanical ambiguity determines the superselection structure of the physical Hilbert space. Prospects of generalising the analysis to systems with several constraints are discussed. |
1310.3938 | Judy Kupferman | Judy Kupferman | Curvature independence of statistical entropy | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the statistical number of states, from which statistical entropy
can be derived, and we show that it is an explicit function of the metric and
thus observer dependent. We find a constraint on a transformation of the metric
that preserves the number of states but does not preserve curvature. In showing
exactly how curvature independence arises in the conventional definition of
statistical entropy, we gain a precise understanding of the direction in which
it needs to be redefined in the treatment of black hole entropy.
| [
{
"created": "Tue, 15 Oct 2013 07:27:01 GMT",
"version": "v1"
},
{
"created": "Sun, 20 Jul 2014 15:20:24 GMT",
"version": "v2"
}
] | 2014-07-22 | [
[
"Kupferman",
"Judy",
""
]
] | We examine the statistical number of states, from which statistical entropy can be derived, and we show that it is an explicit function of the metric and thus observer dependent. We find a constraint on a transformation of the metric that preserves the number of states but does not preserve curvature. In showing exactly how curvature independence arises in the conventional definition of statistical entropy, we gain a precise understanding of the direction in which it needs to be redefined in the treatment of black hole entropy. |
0912.2510 | Khaled Saaidi | A. Aghmohammadi, Kh. Saaidi, M. R. Abolhassani and A. Vajdi | Standard Cosmological Evolution in f(R) Model to Kaluza Klein Cosmology | 12 pages | Phys. Scripta 80: 065008 (2009) | 10.1088/0031-8949/80/06/065008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, using $f(R)$ theory of gravity we explicitly calculate
cosmological evolution in the presence of a perfect fluid source in four and
five dimensional, space time in which this cosmological evolution in
self-creation is presented by Reddy et al 2009 Int. J. Theor. Phys. 48 10. An
exact cosmological model is presented using a relation between Einstein gravity
field equation components due to a metric with the same component from $f(R)$
theory of gravity. Some physics and kinematical properties of the model are
also discussed.
| [
{
"created": "Sun, 13 Dec 2009 15:30:52 GMT",
"version": "v1"
}
] | 2014-01-20 | [
[
"Aghmohammadi",
"A.",
""
],
[
"Saaidi",
"Kh.",
""
],
[
"Abolhassani",
"M. R.",
""
],
[
"Vajdi",
"A.",
""
]
] | In this paper, using $f(R)$ theory of gravity we explicitly calculate cosmological evolution in the presence of a perfect fluid source in four and five dimensional, space time in which this cosmological evolution in self-creation is presented by Reddy et al 2009 Int. J. Theor. Phys. 48 10. An exact cosmological model is presented using a relation between Einstein gravity field equation components due to a metric with the same component from $f(R)$ theory of gravity. Some physics and kinematical properties of the model are also discussed. |
2404.00895 | Muhammad Sharif | M. Sharif, M. Zeeshan Gul and Nusrat Fatima | Analysis of Bouncing Cosmology in Non-Riemannian Geometry | 23 pages, 8 figures | New Astronomy 109(2024)102211 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The main objective of this manuscript is to investigate the bouncing
cosmology in the background of $f(\mathcal{Q})$ gravity, where $\mathcal{Q}$
defines the non-metricity. For this purpose, we use the reconstruction approach
and consider a flat Friedmann-Robertson-Walker spacetime with perfect matter
configuration. We examine how the first contracting phase gives the expansion
by using a temporal derivative of the scale factor, i.e., $\dot{a}<0$,
$\dot{a}=0$ and $\dot{a}>0$ give contraction, bounce point and expansion
phases, respectively. Further, we use the order reduction method to solve the
modified field equations as these are very difficult due to the presence of
additional non-linear expressions. It is analyzed that the original singularity
of the universe diminishes for the required bounce conditions. We conclude that
the acceleration occurs near the bouncing point and the considered
$f(\mathcal{Q})$ models are consistent with the current cosmic accelerated
expansion.
| [
{
"created": "Mon, 1 Apr 2024 03:44:09 GMT",
"version": "v1"
}
] | 2024-04-02 | [
[
"Sharif",
"M.",
""
],
[
"Gul",
"M. Zeeshan",
""
],
[
"Fatima",
"Nusrat",
""
]
] | The main objective of this manuscript is to investigate the bouncing cosmology in the background of $f(\mathcal{Q})$ gravity, where $\mathcal{Q}$ defines the non-metricity. For this purpose, we use the reconstruction approach and consider a flat Friedmann-Robertson-Walker spacetime with perfect matter configuration. We examine how the first contracting phase gives the expansion by using a temporal derivative of the scale factor, i.e., $\dot{a}<0$, $\dot{a}=0$ and $\dot{a}>0$ give contraction, bounce point and expansion phases, respectively. Further, we use the order reduction method to solve the modified field equations as these are very difficult due to the presence of additional non-linear expressions. It is analyzed that the original singularity of the universe diminishes for the required bounce conditions. We conclude that the acceleration occurs near the bouncing point and the considered $f(\mathcal{Q})$ models are consistent with the current cosmic accelerated expansion. |
2406.05820 | Syed Masood | Syed Masood, Said Mikki | An information geometric probe for charged black holes in 4D
Einstein-Gauss-Bonnet gravity | 15 pages, 9 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)] have recently proposed a
consistent model of Einstein-Gauss-Bonnet modified gravity in four spacetime
dimensions. This model predicts significant contributions of the Gauss-Bonnet
coupling parameter $\alpha$ to gravitational dynamics, while circumventing the
Lovelock theorem and avoiding Ostrogradsky instability. As a powerful
competitor to general relativity, the model has been examined on various
phenomenological grounds. Here, we employ a technique from thermodynamic
geometry to analyze the thermodynamic phase structure of a charged black hole
with a quantum gravity-inspired entropy relation in this novel modified gravity
scenario. Based on the sign and magnitude of thermodynamic curvature, we
demonstrate that while the theory does not significantly impact larger black
holes, it may lead to multiple phase transitions and accelerate the formation
of black hole remnants at short-distance scales compared to general relativity.
Our analysis focuses solely on the non-extremal geometry case where
$M>\sqrt{Q^2+\alpha}$, with $M$ and $Q$ representing the mass and charge of the
black hole, respectively. We believe that these results may offer insights for
testing the phenomenological consistency of the theory as a potential
alternative to the standard Einstein paradigm.
| [
{
"created": "Sun, 9 Jun 2024 15:13:55 GMT",
"version": "v1"
}
] | 2024-06-11 | [
[
"Masood",
"Syed",
""
],
[
"Mikki",
"Said",
""
]
] | Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)] have recently proposed a consistent model of Einstein-Gauss-Bonnet modified gravity in four spacetime dimensions. This model predicts significant contributions of the Gauss-Bonnet coupling parameter $\alpha$ to gravitational dynamics, while circumventing the Lovelock theorem and avoiding Ostrogradsky instability. As a powerful competitor to general relativity, the model has been examined on various phenomenological grounds. Here, we employ a technique from thermodynamic geometry to analyze the thermodynamic phase structure of a charged black hole with a quantum gravity-inspired entropy relation in this novel modified gravity scenario. Based on the sign and magnitude of thermodynamic curvature, we demonstrate that while the theory does not significantly impact larger black holes, it may lead to multiple phase transitions and accelerate the formation of black hole remnants at short-distance scales compared to general relativity. Our analysis focuses solely on the non-extremal geometry case where $M>\sqrt{Q^2+\alpha}$, with $M$ and $Q$ representing the mass and charge of the black hole, respectively. We believe that these results may offer insights for testing the phenomenological consistency of the theory as a potential alternative to the standard Einstein paradigm. |
1908.10152 | Dimitry Ayzenberg | Askar B. Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi, Sourabh
Nampalliwar | RELXILL_NK: A Black Hole Relativistic Reflection Model for Testing
General Relativity | 8 Pages, 2 figures, 2 tables. Conference proceedings based on a talk
given at the meeting "Recent Progress in Relativistic Astrophysics" (6-8 May
2019, Shanghai, China). Content overlap with arXiv:1902.09665 | null | 10.3390/proceedings2019017007 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we briefly present RELXILL_NK, the first and currently only
readily available model of the relativistic reflection spectrum of black hole
accretion disks that includes non-Kerr solutions for the black hole spacetime,
thus allowing for tests of the Kerr hypothesis and GR. RELXILL_NK makes use of
a general relativistic ray-tracing code to calculate the relativistic effects
of any well-behaved, stationary, axisymmetric, and asymptotically flat black
hole spacetime, while the disk physics is handled through the non-relativistic
X-ray reflection code XILLVER. A number of different flavors are available
within RELXILL_NK; we summarize and compare these flavors using the Johannsen
metric for the black hole spacetime.
| [
{
"created": "Tue, 27 Aug 2019 12:05:56 GMT",
"version": "v1"
}
] | 2021-11-24 | [
[
"Abdikamalov",
"Askar B.",
""
],
[
"Ayzenberg",
"Dimitry",
""
],
[
"Bambi",
"Cosimo",
""
],
[
"Nampalliwar",
"Sourabh",
""
]
] | In this paper, we briefly present RELXILL_NK, the first and currently only readily available model of the relativistic reflection spectrum of black hole accretion disks that includes non-Kerr solutions for the black hole spacetime, thus allowing for tests of the Kerr hypothesis and GR. RELXILL_NK makes use of a general relativistic ray-tracing code to calculate the relativistic effects of any well-behaved, stationary, axisymmetric, and asymptotically flat black hole spacetime, while the disk physics is handled through the non-relativistic X-ray reflection code XILLVER. A number of different flavors are available within RELXILL_NK; we summarize and compare these flavors using the Johannsen metric for the black hole spacetime. |
gr-qc/9810064 | Jorge L. Cervantes-Cota | J.L. Cervantes-Cota, P. Ag. Chauvet | Can induced gravity isotropize Bianchi I, V, or IX Universes? | 24 pages, 5 figures, to be published in Phys. Rev. D15 | Phys.Rev. D59 (1999) 043501 | 10.1103/PhysRevD.59.043501 | null | gr-qc | null | We analyze if Bianchi I, V, and IX models in the Induced Gravity (IG) theory
can evolve to a Friedmann--Roberson--Walker (FRW) expansion due to the
non--minimal coupling of gravity and the scalar field. The analytical results
that we found for the Brans-Dicke (BD) theory are now applied to the IG theory
which has $\omega \ll 1$ ($\omega$ being the square ratio of the Higgs to
Planck mass) in a cosmological era in which the IG--potential is not
significant. We find that the isotropization mechanism crucially depends on the
value of $\omega$. Its smallness also permits inflationary solutions. For the
Bianch V model inflation due to the Higgs potential takes place afterwads, and
subsequently the spontaneous symmetry breaking (SSB) ends with an effective FRW
evolution. The ordinary tests of successful cosmology are well satisfied.
| [
{
"created": "Tue, 20 Oct 1998 15:12:32 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Cervantes-Cota",
"J. L.",
""
],
[
"Chauvet",
"P. Ag.",
""
]
] | We analyze if Bianchi I, V, and IX models in the Induced Gravity (IG) theory can evolve to a Friedmann--Roberson--Walker (FRW) expansion due to the non--minimal coupling of gravity and the scalar field. The analytical results that we found for the Brans-Dicke (BD) theory are now applied to the IG theory which has $\omega \ll 1$ ($\omega$ being the square ratio of the Higgs to Planck mass) in a cosmological era in which the IG--potential is not significant. We find that the isotropization mechanism crucially depends on the value of $\omega$. Its smallness also permits inflationary solutions. For the Bianch V model inflation due to the Higgs potential takes place afterwads, and subsequently the spontaneous symmetry breaking (SSB) ends with an effective FRW evolution. The ordinary tests of successful cosmology are well satisfied. |
1105.3709 | Norbert Bodendorfer | Norbert Bodendorfer, Thomas Thiemann, Andreas Thurn | Towards Loop Quantum Supergravity (LQSG) I. Rarita-Schwinger Sector | 43 pages. v2: Journal version. Some nonessential sign errors in
sections 2 and 3 corrected. Minor clarifications and corrections | Class. Quantum Grav. 30 (2013) 045006 | 10.1088/0264-9381/30/4/045006 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In our companion papers, we managed to derive a connection formulation of
Lorentzian General Relativity in D+1 dimensions with compact gauge group
SO(D+1) such that the connection is Poisson commuting, which implies that Loop
Quantum Gravity quantisation methods apply. We also provided the coupling to
standard matter. In this paper, we extend our methods to derive a connection
formulation of a large class of Lorentzian signature Supergravity theories, in
particular 11d SUGRA and 4d, N = 8 SUGRA, which was in fact the motivation to
consider higher dimensions. Starting from a Hamiltonian formulation in the time
gauge which yields a Spin(D) theory, a major challenge is to extend the
internal gauge group to Spin(D+1) in presence of the Rarita-Schwinger field.
This is non trivial because SUSY typically requires the Rarita-Schwinger field
to be a Majorana fermion for the Lorentzian Clifford algebra and Majorana
representations of the Clifford algebra are not available in the same spacetime
dimension for both Lorentzian and Euclidean signature. We resolve the arising
tension and provide a background independent representation of the non trivial
Dirac antibracket *-algebra for the Majorana field which significantly differs
from the analogous construction for Dirac fields already available in the
literature.
| [
{
"created": "Wed, 18 May 2011 18:25:11 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Feb 2013 19:14:13 GMT",
"version": "v2"
}
] | 2013-02-13 | [
[
"Bodendorfer",
"Norbert",
""
],
[
"Thiemann",
"Thomas",
""
],
[
"Thurn",
"Andreas",
""
]
] | In our companion papers, we managed to derive a connection formulation of Lorentzian General Relativity in D+1 dimensions with compact gauge group SO(D+1) such that the connection is Poisson commuting, which implies that Loop Quantum Gravity quantisation methods apply. We also provided the coupling to standard matter. In this paper, we extend our methods to derive a connection formulation of a large class of Lorentzian signature Supergravity theories, in particular 11d SUGRA and 4d, N = 8 SUGRA, which was in fact the motivation to consider higher dimensions. Starting from a Hamiltonian formulation in the time gauge which yields a Spin(D) theory, a major challenge is to extend the internal gauge group to Spin(D+1) in presence of the Rarita-Schwinger field. This is non trivial because SUSY typically requires the Rarita-Schwinger field to be a Majorana fermion for the Lorentzian Clifford algebra and Majorana representations of the Clifford algebra are not available in the same spacetime dimension for both Lorentzian and Euclidean signature. We resolve the arising tension and provide a background independent representation of the non trivial Dirac antibracket *-algebra for the Majorana field which significantly differs from the analogous construction for Dirac fields already available in the literature. |
1209.3488 | Stoytcho Yazadjiev | S. Yazadjiev | Kaluza-Klein rotating multi-black hole configurations with
electromagnetic field in Einstein-Maxwell-dilaton gravity | 7 papges | null | 10.1103/PhysRevD.86.107504 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new solution in 5D Einstein-Maxwell-dilaton gravity describing
an equilibrium configuration of extremal rotating black holes with lens space
horizon topologies. The basic properties of the solution are investigated and
the basic physical quantities are calculated. It is shown that the black hole
horizons are superconducting in the sense that they expel the magnetic flux
lines.
| [
{
"created": "Sun, 16 Sep 2012 14:25:33 GMT",
"version": "v1"
}
] | 2013-05-30 | [
[
"Yazadjiev",
"S.",
""
]
] | We present a new solution in 5D Einstein-Maxwell-dilaton gravity describing an equilibrium configuration of extremal rotating black holes with lens space horizon topologies. The basic properties of the solution are investigated and the basic physical quantities are calculated. It is shown that the black hole horizons are superconducting in the sense that they expel the magnetic flux lines. |
2305.16193 | Pasquale Bosso | Pasquale Bosso, Giuseppe Gaetano Luciano, Luciano Petruzziello, Fabian
Wagner | 30 years in: Quo vadis generalized uncertainty principle? | 38 pages. Accepted for publication in Classical and Quantum Gravity,
"Special Issue: Focus on Quantum Gravity Phenomenology in the Multi-Messenger
Era: Challenges and Perspectives" | Class.Quant.Grav. 40 (2023) 19, 195014 | 10.1088/1361-6382/acf021 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | According to a number of arguments in quantum gravity, both model-dependent
and model-independent, Heisenberg's uncertainty principle is modified when
approaching the Planck scale. This deformation is attributed to the existence
of a minimal length. The ensuing models have found entry into the literature
under the term Generalized Uncertainty Principle (GUP). In this work, we
discuss several conceptual shortcomings of the underlying framework and
critically review recent developments in the field. In particular, we touch
upon the issues of relativistic and field theoretical generalizations, the
classical limit and the application to composite systems. Furthermore, we
comment on subtleties involving the use of heuristic arguments instead of
explicit calculations. Finally, we present an extensive list of constraints on
the model parameter $\beta$, classifying them on the basis of the degree of
rigour in their derivation and reconsidering the ones subject to problems
associated with composites.
| [
{
"created": "Thu, 25 May 2023 15:53:30 GMT",
"version": "v1"
},
{
"created": "Fri, 18 Aug 2023 09:34:52 GMT",
"version": "v2"
}
] | 2023-10-30 | [
[
"Bosso",
"Pasquale",
""
],
[
"Luciano",
"Giuseppe Gaetano",
""
],
[
"Petruzziello",
"Luciano",
""
],
[
"Wagner",
"Fabian",
""
]
] | According to a number of arguments in quantum gravity, both model-dependent and model-independent, Heisenberg's uncertainty principle is modified when approaching the Planck scale. This deformation is attributed to the existence of a minimal length. The ensuing models have found entry into the literature under the term Generalized Uncertainty Principle (GUP). In this work, we discuss several conceptual shortcomings of the underlying framework and critically review recent developments in the field. In particular, we touch upon the issues of relativistic and field theoretical generalizations, the classical limit and the application to composite systems. Furthermore, we comment on subtleties involving the use of heuristic arguments instead of explicit calculations. Finally, we present an extensive list of constraints on the model parameter $\beta$, classifying them on the basis of the degree of rigour in their derivation and reconsidering the ones subject to problems associated with composites. |
2101.12488 | Alexei Nurmagambetov | A.M. Arslanaliev and A.J. Nurmagambetov | Scattering on Quasi-Spherical Black-Holes: Features and Beyond | 33 pages, 9 figures, 2 tables. Invited paper published in "Beyond the
Standard Models of Physics and Cosmology", special issue of Physics edited by
M.Yu. Khlopov | Physics 2021, 3(1), 17-41 | 10.3390/physics3010004 | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | Recent developments in the gravitational waves interferometry require more
pertinent theoretical models of gravitational waves generation and propagation.
Untouched possible mechanisms of spin-2 spacetime perturbations production, we
will consider their subsequent scattering on other black holes (BHs).
Specifically, we consider a generalization of the Regge-Wheeler-Zerilli
equations for the case of distorted BHs (BHs surrounded with matter) in
Minkowski and Anti-de Sitter spacetimes, the metric potential of which obeys
the Liouville equation. We establish significant differences in scattering
characteristics of waves of different spins and angular momenta, including the
gravitational waves, caused by losing the spherical symmetry of their
propagation background. In particular, we demonstrate the strong impact of the
background geometry deformation on the grey-body factors, hence on the
absorption cross-sections of scattering waves, and explore the issue of
stability of the background geometry upon changing the deformation degree
parameters.
| [
{
"created": "Fri, 29 Jan 2021 09:32:27 GMT",
"version": "v1"
}
] | 2021-02-01 | [
[
"Arslanaliev",
"A. M.",
""
],
[
"Nurmagambetov",
"A. J.",
""
]
] | Recent developments in the gravitational waves interferometry require more pertinent theoretical models of gravitational waves generation and propagation. Untouched possible mechanisms of spin-2 spacetime perturbations production, we will consider their subsequent scattering on other black holes (BHs). Specifically, we consider a generalization of the Regge-Wheeler-Zerilli equations for the case of distorted BHs (BHs surrounded with matter) in Minkowski and Anti-de Sitter spacetimes, the metric potential of which obeys the Liouville equation. We establish significant differences in scattering characteristics of waves of different spins and angular momenta, including the gravitational waves, caused by losing the spherical symmetry of their propagation background. In particular, we demonstrate the strong impact of the background geometry deformation on the grey-body factors, hence on the absorption cross-sections of scattering waves, and explore the issue of stability of the background geometry upon changing the deformation degree parameters. |
2208.02607 | Jan Ambjorn | Jan Ambjorn and Yoshiyuki Watabiki | The large scale structure of the Universe from a modified Friedmann
equation | null | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have already shown how a modified Friedmann equation, originating from a
model of the Universe built from a certain $W_3$ algebra, is able to explainthe
difference between the Hubble constants extracted from CMB data and from local
measurements. In this article we show that the same model also describes
aspects of the large scale structure of the Universe well.
| [
{
"created": "Wed, 3 Aug 2022 14:19:28 GMT",
"version": "v1"
}
] | 2022-08-05 | [
[
"Ambjorn",
"Jan",
""
],
[
"Watabiki",
"Yoshiyuki",
""
]
] | We have already shown how a modified Friedmann equation, originating from a model of the Universe built from a certain $W_3$ algebra, is able to explainthe difference between the Hubble constants extracted from CMB data and from local measurements. In this article we show that the same model also describes aspects of the large scale structure of the Universe well. |
gr-qc/0106019 | Miroslav Pardy | Miroslav Pardy | Deflection of light by the screw dislocation in space-time | 6 p | null | null | null | gr-qc | null | We derive the light deflection caused by the screw dislocation in space-time.
The derivation is based on the idea that space-time is a medium which can be
deformed by gravity and that the deformation of space-time is equivalent to the
existence of gravity.
| [
{
"created": "Wed, 6 Jun 2001 10:18:20 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Pardy",
"Miroslav",
""
]
] | We derive the light deflection caused by the screw dislocation in space-time. The derivation is based on the idea that space-time is a medium which can be deformed by gravity and that the deformation of space-time is equivalent to the existence of gravity. |
0909.1160 | Sigbjorn Hervik | A Coley and S Hervik | Higher dimensional bivectors and classification of the Weyl operator | 25 pages; v2: some notation changed, typos fixed; CQG accepted | Class.Quant.Grav.27:015002,2010 | 10.1088/0264-9381/27/1/015002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We develop the bivector formalism in higher dimensional Lorentzian
spacetimes. We define the Weyl bivector operator in a manner consistent with
its boost-weight decomposition. We then algebraically classify the Weyl tensor,
which gives rise to a refinement in dimensions higher than four of the usual
alignment (boost-weight) classification, in terms of the irreducible
representations of the spins. We are consequently able to define a number of
new algebraically special cases. In particular, the classification in five
dimensions is discussed in some detail. In addition, utilizing the (refined)
algebraic classification, we are able to prove some interesting results when
the Weyl tensor has (additional) symmetries.
| [
{
"created": "Mon, 7 Sep 2009 08:21:14 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Nov 2009 11:52:02 GMT",
"version": "v2"
}
] | 2010-01-06 | [
[
"Coley",
"A",
""
],
[
"Hervik",
"S",
""
]
] | We develop the bivector formalism in higher dimensional Lorentzian spacetimes. We define the Weyl bivector operator in a manner consistent with its boost-weight decomposition. We then algebraically classify the Weyl tensor, which gives rise to a refinement in dimensions higher than four of the usual alignment (boost-weight) classification, in terms of the irreducible representations of the spins. We are consequently able to define a number of new algebraically special cases. In particular, the classification in five dimensions is discussed in some detail. In addition, utilizing the (refined) algebraic classification, we are able to prove some interesting results when the Weyl tensor has (additional) symmetries. |
2001.08833 | Abhay Ashtekar | Abhay Ashtekar | Black Hole evaporation: A Perspective from Loop Quantum Gravity | 25 pages, 8 Figures. Invited article for a special issue "Probing New
Physics with Black Holes", edited by Aurelien Barrau | Universe , 6, 21 (2020) (22 pages) | 10.3390/universe6020021 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A personal perspective on the black hole evaporation process is presented
using as guidelines inputs from: (i) loop quantum gravity, (ii) simplified
models where concrete results have been obtained, and, (iii) semi-classical
quantum general relativity. On the one hand, the final picture is conservative
in that there are concrete results that support each stage of the argument, and
there are no large departures from general relativity or semi-classical gravity
in tame regions outside macroscopic black holes. On the other hand it argues
against certain views that are commonly held in many quarters, such as:
persistence of a piece of singularity that constitutes a part of the final
boundary of space-time; presence of an \emph{event} horizon serving as an
absolute barrier between the interior and the exterior; and the (often
implicit) requirement that purification must be completed by the time the `last
rays' representing the extension of this event horizon reach $\mathcal{I}^{+}$.
| [
{
"created": "Thu, 23 Jan 2020 22:21:26 GMT",
"version": "v1"
}
] | 2021-01-14 | [
[
"Ashtekar",
"Abhay",
""
]
] | A personal perspective on the black hole evaporation process is presented using as guidelines inputs from: (i) loop quantum gravity, (ii) simplified models where concrete results have been obtained, and, (iii) semi-classical quantum general relativity. On the one hand, the final picture is conservative in that there are concrete results that support each stage of the argument, and there are no large departures from general relativity or semi-classical gravity in tame regions outside macroscopic black holes. On the other hand it argues against certain views that are commonly held in many quarters, such as: persistence of a piece of singularity that constitutes a part of the final boundary of space-time; presence of an \emph{event} horizon serving as an absolute barrier between the interior and the exterior; and the (often implicit) requirement that purification must be completed by the time the `last rays' representing the extension of this event horizon reach $\mathcal{I}^{+}$. |
2402.15327 | Araceli Soler Oficial | David Brizuela, Marco de Cesare and Araceli Soler Oficial | Perturbations of bimetric gravity on most general spherically symmetric
spacetimes | For a better clarity, some notation has been changed. Matches the
published version | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a formalism to study linear perturbations of bimetric gravity on
any spherically symmetric background, including dynamical spacetimes. The setup
is based on the Gerlach-Sengupta formalism for general relativity. Each of the
two background metrics is written as a warped product between a two-dimensional
Lorentzian metric and the round metric of the two-sphere. The different
perturbations are then decomposed in terms of tensor spherical harmonics, which
makes the two polarity (axial and polar) sectors decouple. In addition, a
covariant notation on the Lorentzian manifold is used so that all expressions
are valid for any coordinates. In this theory, there are seven physical
propagating degrees of freedom, which, as compared to the two degrees of
freedom of general relativity, makes the dynamics much more intricate. In
particular, we discuss the amount of gauge and physical degrees of freedom for
different polarities and multipoles. Finally, as an interesting application, we
analyze static nonbidiagonal backgrounds and derive the corresponding
perturbative equations.
| [
{
"created": "Fri, 23 Feb 2024 13:46:52 GMT",
"version": "v1"
},
{
"created": "Mon, 13 May 2024 14:41:08 GMT",
"version": "v2"
},
{
"created": "Mon, 1 Jul 2024 07:07:34 GMT",
"version": "v3"
}
] | 2024-07-02 | [
[
"Brizuela",
"David",
""
],
[
"de Cesare",
"Marco",
""
],
[
"Oficial",
"Araceli Soler",
""
]
] | We present a formalism to study linear perturbations of bimetric gravity on any spherically symmetric background, including dynamical spacetimes. The setup is based on the Gerlach-Sengupta formalism for general relativity. Each of the two background metrics is written as a warped product between a two-dimensional Lorentzian metric and the round metric of the two-sphere. The different perturbations are then decomposed in terms of tensor spherical harmonics, which makes the two polarity (axial and polar) sectors decouple. In addition, a covariant notation on the Lorentzian manifold is used so that all expressions are valid for any coordinates. In this theory, there are seven physical propagating degrees of freedom, which, as compared to the two degrees of freedom of general relativity, makes the dynamics much more intricate. In particular, we discuss the amount of gauge and physical degrees of freedom for different polarities and multipoles. Finally, as an interesting application, we analyze static nonbidiagonal backgrounds and derive the corresponding perturbative equations. |
gr-qc/9901030 | Wolfgang Drechsler | Wolfgang Drechsler (MPI for Physics, Munich, Germany) | Mass-Generation by Weyl-Symmetry Breaking | LaTex, revtex, 36 pages | Found.Phys. 29 (1999) 1327-1369 | 10.1023/A:1018805108859 | MPI-PhT/98-68 | gr-qc hep-th | null | A massless electroweak theory for leptons is formulated in a Weyl space, W_4,
yielding a Weyl invariant gauge dynamics allowing for conformal rescalings of
the metric and all fields with nonvanishing Weyl weight together with the
corresponding transformations of the Weyl vector fields representing the D(1)
or dilatation gauge fields. To study the appearance of nonzero masses this
theory is explicitly broken by a term in the Lagrangean involving the curvature
scalar R of the W_4 and a mass term for the scalar field. Thereby also the
gauge fields as well as the charged fermion field acquire a mass as in the
standard electroweak theory. The symmetry breaking is governed by the relation
D Phi^2=0, where Phi is the modulus of the scalar field and D denotes the
Weyl-covariant derivative. This true symmetry reduction, establishing a scale
of length in the theory, is compared to the so-called spontanous symmetry
breaking in the standard electroweak theory which is, actually, the choice of a
particular (nonlinear) gauge obtained by adopting an origin in the coset space
representing the scalar field which is invariant under the electromagnetic
gauge group. Particular attention is devoted to the appearance of Einstein's
equations for the metric after the Weyl-symmetry breaking yielding a
pseudo-Riemannian space V_4 from a W_4 and a scalar field with a constant
modulus which in turn affects Einstein's gravitational constant in a manner
comparable to the Brans-Dicke theory.
| [
{
"created": "Mon, 11 Jan 1999 17:22:07 GMT",
"version": "v1"
}
] | 2022-10-12 | [
[
"Drechsler",
"Wolfgang",
"",
"MPI for Physics, Munich, Germany"
]
] | A massless electroweak theory for leptons is formulated in a Weyl space, W_4, yielding a Weyl invariant gauge dynamics allowing for conformal rescalings of the metric and all fields with nonvanishing Weyl weight together with the corresponding transformations of the Weyl vector fields representing the D(1) or dilatation gauge fields. To study the appearance of nonzero masses this theory is explicitly broken by a term in the Lagrangean involving the curvature scalar R of the W_4 and a mass term for the scalar field. Thereby also the gauge fields as well as the charged fermion field acquire a mass as in the standard electroweak theory. The symmetry breaking is governed by the relation D Phi^2=0, where Phi is the modulus of the scalar field and D denotes the Weyl-covariant derivative. This true symmetry reduction, establishing a scale of length in the theory, is compared to the so-called spontanous symmetry breaking in the standard electroweak theory which is, actually, the choice of a particular (nonlinear) gauge obtained by adopting an origin in the coset space representing the scalar field which is invariant under the electromagnetic gauge group. Particular attention is devoted to the appearance of Einstein's equations for the metric after the Weyl-symmetry breaking yielding a pseudo-Riemannian space V_4 from a W_4 and a scalar field with a constant modulus which in turn affects Einstein's gravitational constant in a manner comparable to the Brans-Dicke theory. |
gr-qc/0407108 | Carlos F. Sopuerta | Andrea Passamonti, Marco Bruni, Leonardo Gualtieri, Carlos F. Sopuerta | Coupling of radial and non-radial oscillations of relativistic stars:
gauge-invariant formalism | 23 pages, no figures, RevTeX 4.0. Minor changes to fit the version to
appear in PRD | Phys.Rev. D71 (2005) 024022 | 10.1103/PhysRevD.71.024022 | null | gr-qc astro-ph | null | Linear perturbation theory is appropriate to describe small oscillations of
stars, while a mild non-linearity is still tractable perturbatively but
requires to consider mode coupling. It is natural to start to look at this
problem by considering the coupling between linear radial and non-radial modes.
Radial pulsations of a spherical compact objects do not per se emit
gravitational waves but, if the coupling is efficient in driving and possibly
amplifying the non-radial modes, gravitational radiation could then be produced
to a significant level.
In this paper we develop the relativistic formalism to study the coupling of
radial and non-radial first order perturbations of a compact spherical star.
From a mathematical point of view, it is convenient to treat the two sets of
perturbations as separately parametrized, using a 2-parameter perturbative
expansion of the metric, the energy-momentum tensor and Einstein equations in
which $\lambda$ is associated with the radial modes, $\epsilon$ with the
non-radial perturbations, and the $\lambda\epsilon$ terms describe the
coupling. This approach provides a well-defined framework to consider the gauge
dependence of perturbations, allowing us to use $\epsilon$ order
gauge-invariant non-radial variables on the static background and to define new
second order $\lambda\epsilon$ gauge-invariant variables describing the
non-linear coupling. We present the evolution and constraint equations for our
variables outlining the setup for numerical computations, and briefly discuss
the surface boundary conditions in terms of the second order $\lambda\epsilon$
Lagrangian pressure perturbation.
| [
{
"created": "Wed, 28 Jul 2004 20:23:16 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Jan 2005 18:17:09 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Passamonti",
"Andrea",
""
],
[
"Bruni",
"Marco",
""
],
[
"Gualtieri",
"Leonardo",
""
],
[
"Sopuerta",
"Carlos F.",
""
]
] | Linear perturbation theory is appropriate to describe small oscillations of stars, while a mild non-linearity is still tractable perturbatively but requires to consider mode coupling. It is natural to start to look at this problem by considering the coupling between linear radial and non-radial modes. Radial pulsations of a spherical compact objects do not per se emit gravitational waves but, if the coupling is efficient in driving and possibly amplifying the non-radial modes, gravitational radiation could then be produced to a significant level. In this paper we develop the relativistic formalism to study the coupling of radial and non-radial first order perturbations of a compact spherical star. From a mathematical point of view, it is convenient to treat the two sets of perturbations as separately parametrized, using a 2-parameter perturbative expansion of the metric, the energy-momentum tensor and Einstein equations in which $\lambda$ is associated with the radial modes, $\epsilon$ with the non-radial perturbations, and the $\lambda\epsilon$ terms describe the coupling. This approach provides a well-defined framework to consider the gauge dependence of perturbations, allowing us to use $\epsilon$ order gauge-invariant non-radial variables on the static background and to define new second order $\lambda\epsilon$ gauge-invariant variables describing the non-linear coupling. We present the evolution and constraint equations for our variables outlining the setup for numerical computations, and briefly discuss the surface boundary conditions in terms of the second order $\lambda\epsilon$ Lagrangian pressure perturbation. |
1610.08850 | Suddhasattwa Brahma | Martin Bojowald and Suddhasattwa Brahma | Signature change in 2-dimensional black-hole models of loop quantum
gravity | 18 pages | Phys. Rev. D 98, 026012 (2018) | 10.1103/PhysRevD.98.026012 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Signature change has been identified as a generic consequence of holonomy
modifications in spherically symmetric models of loop quantum gravity with real
connections, which includes modified Schwarzschild solutions. Here, this result
is extended to 2-dimensional dilaton models and to different choices of
canonical variables, including in particular the
Callan-Giddings-Harvey-Strominger (CGHS) solution. New obstructions are found
to coupling matter and to including operator-ordering effects in an
anomaly-free manner.
| [
{
"created": "Thu, 27 Oct 2016 15:51:31 GMT",
"version": "v1"
}
] | 2018-07-18 | [
[
"Bojowald",
"Martin",
""
],
[
"Brahma",
"Suddhasattwa",
""
]
] | Signature change has been identified as a generic consequence of holonomy modifications in spherically symmetric models of loop quantum gravity with real connections, which includes modified Schwarzschild solutions. Here, this result is extended to 2-dimensional dilaton models and to different choices of canonical variables, including in particular the Callan-Giddings-Harvey-Strominger (CGHS) solution. New obstructions are found to coupling matter and to including operator-ordering effects in an anomaly-free manner. |
gr-qc/0006036 | Tony Rothman | Tony Rothman | Nonthermal nature of extremal Kerr black holes | Latex file, 8 pages This post corrects several misprints | Phys.Lett. A273 (2000) 303-309 | 10.1016/S0375-9601(00)00515-6 | null | gr-qc | null | Liberati, Rothman and Sonego have recently showed that objects collapsing
into extremal Reissner-Nordstrom black holes do not behave as thermal objects
at any time in their history. In particular, a temperature, and hence
thermodynamic entropy, are undefined for them. I demonstrate that the analysis
goes through essentially unchanged for Kerr black holes.
| [
{
"created": "Mon, 12 Jun 2000 10:23:32 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Mar 2001 17:03:23 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Rothman",
"Tony",
""
]
] | Liberati, Rothman and Sonego have recently showed that objects collapsing into extremal Reissner-Nordstrom black holes do not behave as thermal objects at any time in their history. In particular, a temperature, and hence thermodynamic entropy, are undefined for them. I demonstrate that the analysis goes through essentially unchanged for Kerr black holes. |
gr-qc/0011032 | Andrzej Krolak | Andrzej Krolak and Massimo Tinto | Resampled random processes in gravitational-wave data analysis | 7 pages | Phys.Rev. D63 (2001) 107101 | 10.1103/PhysRevD.63.107101 | null | gr-qc | null | The detection of continuous gravitational-wave signals requires to account
for the motion of the detector with respect to the solar system barycenter in
the data analysis. In order to search efficiently for such signals by means of
the fast Fourier transform the data needs to be transformed from the
topocentric time to the barycentric time by means of resampling. The resampled
data form a non-stationary random process. In this communication we prove that
this non-stationary random process is mathematically well defined, and show
that generalizations of the fundamental results for stationary processes, like
Wiener-Khintchine theorem and Cram\`{e}r representation, exist.
| [
{
"created": "Wed, 8 Nov 2000 09:43:07 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Nov 2000 10:47:28 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Krolak",
"Andrzej",
""
],
[
"Tinto",
"Massimo",
""
]
] | The detection of continuous gravitational-wave signals requires to account for the motion of the detector with respect to the solar system barycenter in the data analysis. In order to search efficiently for such signals by means of the fast Fourier transform the data needs to be transformed from the topocentric time to the barycentric time by means of resampling. The resampled data form a non-stationary random process. In this communication we prove that this non-stationary random process is mathematically well defined, and show that generalizations of the fundamental results for stationary processes, like Wiener-Khintchine theorem and Cram\`{e}r representation, exist. |
2303.05870 | Robert Beig | Robert Beig | Relativistic Elasticity II | 28 pages, to be published in Special Issue of Class. Quantum Gravity
on 'Focus on the Mathematics of Gravitation in the Non-Vacuum Regime' | null | 10.1088/1361-6382/acc307 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | This paper is based on a series of talks given at the ESI program on
'Mathematical Perspectives of Gravitation Beyond the Vacuum Regime' in February
2022. It is meant to be an introduction to the field of relativistic elasticity
for readers with a good base in the mathematics of General Relativity with no
necessary previous of knowledge of elasticity either in the classical or
relativistic domain. Despite its introductory purpose, the present work has new
material, in particular related to the formal structure of the theory.
| [
{
"created": "Fri, 10 Mar 2023 11:41:45 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Mar 2023 08:22:12 GMT",
"version": "v2"
}
] | 2023-03-24 | [
[
"Beig",
"Robert",
""
]
] | This paper is based on a series of talks given at the ESI program on 'Mathematical Perspectives of Gravitation Beyond the Vacuum Regime' in February 2022. It is meant to be an introduction to the field of relativistic elasticity for readers with a good base in the mathematics of General Relativity with no necessary previous of knowledge of elasticity either in the classical or relativistic domain. Despite its introductory purpose, the present work has new material, in particular related to the formal structure of the theory. |
2110.05397 | Saeed Rastgoo | Keagan Blanchette, Saurya Das, Samantha Hergott, Saeed Rastgoo | Effective black hole interior and the Raychadhuri equation | This is the contribution to the Proceedings of the MG16 Conference.
11 pages, 4 figures; v2: citations added | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that loop quantum gravity effects leads to the finiteness of
expansion and its rate of change in the effective regime in the interior of the
Schwarzschild black hole. As a consequence the singularity is resolved. We find
this in line with previous results about curvature scalar and strong curvature
singularities in Kantowski-Sachs model which is isometric to Schwarzschild
interior.
| [
{
"created": "Mon, 11 Oct 2021 16:35:13 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Mar 2022 19:23:27 GMT",
"version": "v2"
}
] | 2022-03-07 | [
[
"Blanchette",
"Keagan",
""
],
[
"Das",
"Saurya",
""
],
[
"Hergott",
"Samantha",
""
],
[
"Rastgoo",
"Saeed",
""
]
] | We show that loop quantum gravity effects leads to the finiteness of expansion and its rate of change in the effective regime in the interior of the Schwarzschild black hole. As a consequence the singularity is resolved. We find this in line with previous results about curvature scalar and strong curvature singularities in Kantowski-Sachs model which is isometric to Schwarzschild interior. |
2401.08269 | Matteo Carlesso | Jos\'e Luis Gaona-Reyes, Luc\'ia Men\'endez-Pidal, Mir Faizal, Matteo
Carlesso | Spontaneous collapse models lead to the emergence of classicality of the
Universe | null | J. High Energ. Phys. 2024, 193 (2024) | 10.1007/JHEP02(2024)193 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Assuming that Quantum Mechanics is universal and that it can be applied over
all scales, then the Universe is allowed to be in a quantum superposition of
states, where each of them can correspond to a different space-time geometry.
How can one then describe the emergence of the classical, well-defined geometry
that we observe? Considering that the decoherence-driven quantum-to-classical
transition relies on external physical entities, this process cannot account
for the emergence of the classical behaviour of the Universe. Here, we show how
models of spontaneous collapse of the wavefunction can offer a viable mechanism
for explaining such an emergence. We apply it to a simple General Relativity
dynamical model for gravity and a perfect fluid. We show that, by starting from
a general quantum superposition of different geometries, the collapse dynamics
leads to a single geometry, thus providing a possible mechanism for the
quantum-to-classical transition of the Universe. Similarly, when applying our
dynamics to the physically-equivalent Parametrised Unimodular gravity model, we
obtain a collapse on the basis of the cosmological constant, where eventually
one precise value is selected, thus providing also a viable explanation for the
cosmological constant problem. Our formalism can be easily applied to other
quantum cosmological models where we can choose a well-defined clock variable.
| [
{
"created": "Tue, 16 Jan 2024 10:46:29 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Feb 2024 10:37:44 GMT",
"version": "v2"
}
] | 2024-02-27 | [
[
"Gaona-Reyes",
"José Luis",
""
],
[
"Menéndez-Pidal",
"Lucía",
""
],
[
"Faizal",
"Mir",
""
],
[
"Carlesso",
"Matteo",
""
]
] | Assuming that Quantum Mechanics is universal and that it can be applied over all scales, then the Universe is allowed to be in a quantum superposition of states, where each of them can correspond to a different space-time geometry. How can one then describe the emergence of the classical, well-defined geometry that we observe? Considering that the decoherence-driven quantum-to-classical transition relies on external physical entities, this process cannot account for the emergence of the classical behaviour of the Universe. Here, we show how models of spontaneous collapse of the wavefunction can offer a viable mechanism for explaining such an emergence. We apply it to a simple General Relativity dynamical model for gravity and a perfect fluid. We show that, by starting from a general quantum superposition of different geometries, the collapse dynamics leads to a single geometry, thus providing a possible mechanism for the quantum-to-classical transition of the Universe. Similarly, when applying our dynamics to the physically-equivalent Parametrised Unimodular gravity model, we obtain a collapse on the basis of the cosmological constant, where eventually one precise value is selected, thus providing also a viable explanation for the cosmological constant problem. Our formalism can be easily applied to other quantum cosmological models where we can choose a well-defined clock variable. |
gr-qc/0402073 | Giovanni Montani | Andrea Marrocco and Giovanni Montani | QED Coupling from a 5-D Kaluza-Klein Theory | 3 pages, no figures, proceedings of the X Marcel Grossmann Meeting,
22-26 July 2003, Rio de Janeiro | null | 10.1142/9789812704030_0132 | null | gr-qc hep-th | null | We discuss the possibility to obtain, from a five-dimensional free spinor
Lagrangian, the Quantum Electro-Dynamics (QED) coupling via a Kaluza-Klein
reduction of the theory. This result is achieved taking a phase dependence of
the spinor field on the extra-coordinate and modifying the corresponding
connection. The five-dimensional spinor theory is covariant under the
admissible coordinates transformations and its four-dimensional reduction
provides the QED coupling term.
| [
{
"created": "Mon, 16 Feb 2004 10:45:22 GMT",
"version": "v1"
}
] | 2016-11-09 | [
[
"Marrocco",
"Andrea",
""
],
[
"Montani",
"Giovanni",
""
]
] | We discuss the possibility to obtain, from a five-dimensional free spinor Lagrangian, the Quantum Electro-Dynamics (QED) coupling via a Kaluza-Klein reduction of the theory. This result is achieved taking a phase dependence of the spinor field on the extra-coordinate and modifying the corresponding connection. The five-dimensional spinor theory is covariant under the admissible coordinates transformations and its four-dimensional reduction provides the QED coupling term. |
gr-qc/0004068 | Ulises Nucamendi | Ulises Nucamendi and Daniel Sudarsky | Black Holes with Zero Mass | 10 pages, 2 ps figures, REVTeX, some minor changes | Class.Quant.Grav. 17 (2000) 4051-4058 | 10.1088/0264-9381/17/19/306 | null | gr-qc astro-ph hep-th | null | We consider the spacetimes corresponding to static Global Monopoles with
interior boundaries corresponding to a Black Hole Horizon and analyze the
behavior of the appropriate ADM mass as a function of the horizon radius r_H.
We find that for small enough r_H, this mass is negative as in the case of the
regular global monopoles, but that for large enough r_H the mass becomes
positive encountering an intermediate value for which we have a Black Hole with
zero ADM mass.
| [
{
"created": "Thu, 20 Apr 2000 15:08:53 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Sep 2000 16:13:16 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Nucamendi",
"Ulises",
""
],
[
"Sudarsky",
"Daniel",
""
]
] | We consider the spacetimes corresponding to static Global Monopoles with interior boundaries corresponding to a Black Hole Horizon and analyze the behavior of the appropriate ADM mass as a function of the horizon radius r_H. We find that for small enough r_H, this mass is negative as in the case of the regular global monopoles, but that for large enough r_H the mass becomes positive encountering an intermediate value for which we have a Black Hole with zero ADM mass. |
1709.07709 | Helmut Friedrich | Helmut Friedrich | Peeling or not peeling -- is that the question ? | 22 pages, added reference, removed typos | null | 10.1088/1361-6382/aaafdb | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The concepts of isolated self-gravitating system, asymptotic flatness and
asymptotic simplicity are reconsidered, various related results are discussed
and put into perspective, basic open questions are posed.
| [
{
"created": "Fri, 22 Sep 2017 12:25:57 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Feb 2018 09:59:51 GMT",
"version": "v2"
}
] | 2018-03-28 | [
[
"Friedrich",
"Helmut",
""
]
] | The concepts of isolated self-gravitating system, asymptotic flatness and asymptotic simplicity are reconsidered, various related results are discussed and put into perspective, basic open questions are posed. |
1206.1192 | Aurelien Barrau | Aurelien Barrau, Julien Grain | Quantum gravity in the sky | Brief essay written for the "Gravity Research Foundation" and updated
as an introduction for a lecture on the philosophy of gravity | null | null | null | gr-qc astro-ph.CO hep-th physics.hist-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum gravity is known to be mostly a kind of metaphysical speculation. In
this brief essay, we try to argue that, although still extremely difficult to
reach, observational signatures can in fact be expected. The early universe is
an invaluable laboratory to probe "Planck scale physics". With the example of
Loop Quantum Gravity, we detail some expected features.
| [
{
"created": "Wed, 6 Jun 2012 11:59:40 GMT",
"version": "v1"
}
] | 2012-06-07 | [
[
"Barrau",
"Aurelien",
""
],
[
"Grain",
"Julien",
""
]
] | Quantum gravity is known to be mostly a kind of metaphysical speculation. In this brief essay, we try to argue that, although still extremely difficult to reach, observational signatures can in fact be expected. The early universe is an invaluable laboratory to probe "Planck scale physics". With the example of Loop Quantum Gravity, we detail some expected features. |
gr-qc/0101102 | Racz Istvan | Istv\'an R\'acz | On rigidity of spacetimes with a compact Cauchy horizon | 2 pages, contribution to the 9th Marcel Grossmann meeting (MG9),
Rome, July 2000 | null | 10.1142/9789812777386_0138 | null | gr-qc | null | Smooth spacetimes with a compact Cauchy horizon ruled by closed null
geodesics are considered. The compact Cauchy horizon is assumed to be
non-degenerate. Then, supporting the validity of Penrose's strong cosmic censor
hypothesis, the existence of a smooth Killing vector field in a neighbourhood
of the horizon on the Cauchy development side is shown.
| [
{
"created": "Fri, 26 Jan 2001 15:31:24 GMT",
"version": "v1"
}
] | 2017-08-23 | [
[
"Rácz",
"István",
""
]
] | Smooth spacetimes with a compact Cauchy horizon ruled by closed null geodesics are considered. The compact Cauchy horizon is assumed to be non-degenerate. Then, supporting the validity of Penrose's strong cosmic censor hypothesis, the existence of a smooth Killing vector field in a neighbourhood of the horizon on the Cauchy development side is shown. |
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