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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2309.04203 | Dionysios Kokkinos | D. Kokkinos and T. Papakostas | Carter's case [D] admits the 2nd Canonical Form of the Killing Tensor | null | null | null | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The study of the Canonical Forms of the Killing Tensor concerns the
simultaneous resolving of the Integrability Conditions of the Killing Tensor
along with the Einstein's Field Equations employing the framework of
Newman-Penrose Formalism. We present all the Petrov Types admitting the 2nd and
3rd Canonical Forms of Killing Tensor in Vacuum in the frame of General Theory
of Relativity. During the investigation of the Type D solution of 2nd Canonical
form of the Killing Tensor the Carter's Case [D] solution in Vacuum emerged.
| [
{
"created": "Fri, 8 Sep 2023 08:28:02 GMT",
"version": "v1"
}
] | 2023-09-11 | [
[
"Kokkinos",
"D.",
""
],
[
"Papakostas",
"T.",
""
]
] | The study of the Canonical Forms of the Killing Tensor concerns the simultaneous resolving of the Integrability Conditions of the Killing Tensor along with the Einstein's Field Equations employing the framework of Newman-Penrose Formalism. We present all the Petrov Types admitting the 2nd and 3rd Canonical Forms of Killing Tensor in Vacuum in the frame of General Theory of Relativity. During the investigation of the Type D solution of 2nd Canonical form of the Killing Tensor the Carter's Case [D] solution in Vacuum emerged. |
1809.03810 | Shoulong Li | Shou-Long Li and Hao Wei | Holographic Entanglement Entropy and Van der Waals transitions in
Einstein-Maxwell-dilaton theory | Latex, 25 pages, 7 figures, published version | Phys. Rev. D 99, 064002 (2019) | 10.1103/PhysRevD.99.064002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | According to the gauge/gravity duality, the Van der Waals transition of
charged AdS black holes in extended phase space is conjectured to be dual to a
renormalization group flow on the space of field theories. So exploring the Van
der Waals transition is potentially valuable for studying holographic
properties of charged black hole thermodynamics. There are different transition
behaviors for charged dilatonic AdS black holes in Einstein-Maxwell-dilaton
(EMD) theory with string-inspired potential with different dilaton coupling
constants in diverse dimensions. In this work, we find a special class of
charged dilatonic AdS black holes which have the standard Van der Waals
transition. We study the extended thermodynamics of the special class of black
holes, which, in the extremal limit, have near-horizon geometry conformal to
AdS$_2 \times S^{D-2}$. We find that, for these black holes, both the
pressure-volume transition in fixed charge ensemble and the inverse
temperature-entropy transition in fixed pressure ensemble have the standard Van
der Waals behaviors. We also find the holographic entanglement entropy
undergoes the same transition behaviors for the same critical temperature in
fixing the thermodynamic pressure ensemble.
| [
{
"created": "Tue, 11 Sep 2018 12:16:12 GMT",
"version": "v1"
},
{
"created": "Sun, 10 Mar 2019 11:36:42 GMT",
"version": "v2"
}
] | 2019-03-13 | [
[
"Li",
"Shou-Long",
""
],
[
"Wei",
"Hao",
""
]
] | According to the gauge/gravity duality, the Van der Waals transition of charged AdS black holes in extended phase space is conjectured to be dual to a renormalization group flow on the space of field theories. So exploring the Van der Waals transition is potentially valuable for studying holographic properties of charged black hole thermodynamics. There are different transition behaviors for charged dilatonic AdS black holes in Einstein-Maxwell-dilaton (EMD) theory with string-inspired potential with different dilaton coupling constants in diverse dimensions. In this work, we find a special class of charged dilatonic AdS black holes which have the standard Van der Waals transition. We study the extended thermodynamics of the special class of black holes, which, in the extremal limit, have near-horizon geometry conformal to AdS$_2 \times S^{D-2}$. We find that, for these black holes, both the pressure-volume transition in fixed charge ensemble and the inverse temperature-entropy transition in fixed pressure ensemble have the standard Van der Waals behaviors. We also find the holographic entanglement entropy undergoes the same transition behaviors for the same critical temperature in fixing the thermodynamic pressure ensemble. |
2407.03617 | Zeeshan Gul | M. Zeeshan Gul, M. Sharif and Adeeba Arooj | Physical Analysis of Spherical Stellar Structures in
$f(\mathrm{Q},\mathrm{T})$ Theory | 46 pages, 14 figures | Gen. Relativ. Gravit. 56(2024)45 | 10.1007/s10714-024-03234-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper explores the viability and stability of compact stellar objects
characterized by anisotropic matter in the framework of
$f(\mathrm{Q},\mathrm{T})$ theory, where $\mathrm{Q}$ denotes non-metricity and
$\mathrm{T}$ represents the trace of the energy-momentum tensor. We consider a
specific model of this theory to obtain explicit expressions for the field
equations governing the behavior of matter and geometry in this context.
Furthermore, the Karmarkar condition is employed to assess the configuration of
static spherically symmetric structures. The values of unknown constants in the
metric potentials are determined through matching conditions of the interior
and exterior spacetimes. Various physical quantities such as fluid parameters,
energy constraints, equation of state parameters, mass, compactness and
redshift are graphically analyzed to evaluate the viability of the considered
compact stars. The Tolman-Oppenheimer-Volkoff equation is used to examine the
equilibrium state of the stellar models. Moreover, the stability of the
proposed compact stars is investigated through sound speed and adiabatic index
methods. This study concludes that the proposed compact stars analyzed in this
theoretical framework are viable and stable, as all the required conditions are
satisfied.
| [
{
"created": "Thu, 4 Jul 2024 04:00:33 GMT",
"version": "v1"
}
] | 2024-07-08 | [
[
"Gul",
"M. Zeeshan",
""
],
[
"Sharif",
"M.",
""
],
[
"Arooj",
"Adeeba",
""
]
] | This paper explores the viability and stability of compact stellar objects characterized by anisotropic matter in the framework of $f(\mathrm{Q},\mathrm{T})$ theory, where $\mathrm{Q}$ denotes non-metricity and $\mathrm{T}$ represents the trace of the energy-momentum tensor. We consider a specific model of this theory to obtain explicit expressions for the field equations governing the behavior of matter and geometry in this context. Furthermore, the Karmarkar condition is employed to assess the configuration of static spherically symmetric structures. The values of unknown constants in the metric potentials are determined through matching conditions of the interior and exterior spacetimes. Various physical quantities such as fluid parameters, energy constraints, equation of state parameters, mass, compactness and redshift are graphically analyzed to evaluate the viability of the considered compact stars. The Tolman-Oppenheimer-Volkoff equation is used to examine the equilibrium state of the stellar models. Moreover, the stability of the proposed compact stars is investigated through sound speed and adiabatic index methods. This study concludes that the proposed compact stars analyzed in this theoretical framework are viable and stable, as all the required conditions are satisfied. |
gr-qc/0402094 | Hongsu Kim | Hongsu Kim, Hyung Mok Lee | Bonnor-type Black Dihole Solution in Brans-Dicke-Maxwell Theory | 29 pages, Revtex4, Int. J. Mod. Phys. A (IJMPA), in press | Int.J.Mod.Phys. A20 (2005) 6461-6485 | 10.1142/S0217751X05025413 | null | gr-qc astro-ph hep-th | null | It was originally thought that Bonnor's solution in Einstein-Maxwell theory
describes a singular point-like magnetic dipole. Lately, however, it has been
demonstrated that indeed it may describe a black {\it dihole}, i.e., a pair of
static, oppositely-charged extremal black holes with regular horizons.
Motivated particularly by this new interpretation, in the present work, the
construction and extensive analysis of a solution in the context of the
Brans-Dicke-Maxwell theory representing a black dihole are attempted. It has
been known for some time that the solution-generating algorithm of Singh and
Rai produces stationary, axisymmetric, charged solutions in Brans-Dicke-Maxwell
theory from the known such solutions in Einstein-Maxwell theory. Thus this
algorithm of Singh and Rai's is employed in order to construct a Bonnor-type
magnetic black dihole solution in Brans-Dicke-Maxwell theory from the known
Bonnor solution in Einstein-Maxwell theory. The peculiar feature of the new
solution including internal infinity nature of the symmetry axis and its
stability issue have been discussed in full detail.
| [
{
"created": "Mon, 23 Feb 2004 07:44:48 GMT",
"version": "v1"
},
{
"created": "Sat, 25 Jun 2005 04:10:17 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Kim",
"Hongsu",
""
],
[
"Lee",
"Hyung Mok",
""
]
] | It was originally thought that Bonnor's solution in Einstein-Maxwell theory describes a singular point-like magnetic dipole. Lately, however, it has been demonstrated that indeed it may describe a black {\it dihole}, i.e., a pair of static, oppositely-charged extremal black holes with regular horizons. Motivated particularly by this new interpretation, in the present work, the construction and extensive analysis of a solution in the context of the Brans-Dicke-Maxwell theory representing a black dihole are attempted. It has been known for some time that the solution-generating algorithm of Singh and Rai produces stationary, axisymmetric, charged solutions in Brans-Dicke-Maxwell theory from the known such solutions in Einstein-Maxwell theory. Thus this algorithm of Singh and Rai's is employed in order to construct a Bonnor-type magnetic black dihole solution in Brans-Dicke-Maxwell theory from the known Bonnor solution in Einstein-Maxwell theory. The peculiar feature of the new solution including internal infinity nature of the symmetry axis and its stability issue have been discussed in full detail. |
1412.3251 | Jan Steinhoff | Jan Steinhoff | Spin and quadrupole contributions to the motion of astrophysical
binaries | 43 pages. Proceedings of the 524. WE-Heraeus-Seminar "Equations of
Motion in Relativistic Gravity". v2: fixed reference. v3: corrected typos in
eqs. (1), (57), (85) | null | 10.1007/978-3-319-18335-0_19 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Compact objects in general relativity approximately move along geodesics of
spacetime. It is shown that the corrections to geodesic motion due to spin
(dipole), quadrupole, and higher multipoles can be modeled by an extension of
the point mass action. The quadrupole contributions are discussed in detail for
astrophysical objects like neutron stars or black holes. Implications for
binaries are analyzed for a small mass ratio situation. There quadrupole
effects can encode information about the internal structure of the compact
object, e.g., in principle they allow a distinction between black holes and
neutron stars, and also different equations of state for the latter.
Furthermore, a connection between the relativistic oscillation modes of the
object and a dynamical quadrupole evolution is established.
| [
{
"created": "Wed, 10 Dec 2014 10:43:00 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Dec 2014 09:29:10 GMT",
"version": "v2"
},
{
"created": "Mon, 18 Jul 2016 00:03:39 GMT",
"version": "v3"
}
] | 2021-04-07 | [
[
"Steinhoff",
"Jan",
""
]
] | Compact objects in general relativity approximately move along geodesics of spacetime. It is shown that the corrections to geodesic motion due to spin (dipole), quadrupole, and higher multipoles can be modeled by an extension of the point mass action. The quadrupole contributions are discussed in detail for astrophysical objects like neutron stars or black holes. Implications for binaries are analyzed for a small mass ratio situation. There quadrupole effects can encode information about the internal structure of the compact object, e.g., in principle they allow a distinction between black holes and neutron stars, and also different equations of state for the latter. Furthermore, a connection between the relativistic oscillation modes of the object and a dynamical quadrupole evolution is established. |
2012.15004 | Yuuki Sugiyama | Yuuki Sugiyama, Kazuhiro Yamamoto, Tsutomu Kobayashi | Gravitational waves in Kasner spacetimes and Rindler wedges in
Regge-Wheeler gauge: Unruh effect | 23 pages, 1 figure | Phys. Rev. D 103, 083503 (2021) | 10.1103/PhysRevD.103.083503 | RUP-20-35 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the solutions of gravitational waves in the future (F) expanding
and the past (P) shrinking Kanser spacetimes as well as in the left (L) and
right (R) Rindler wedges in the Regge-Wheeler gauge. The solutions for all
metric components are obtained in an analytic form in each region. We identify
the master variables, which are equivalent to massless scalar fields, to
describe the gravitational degrees of freedom for the odd parity and even
parity modes under the transformation in the two-dimensional plane symmetric
space. Then, the master variables are quantized, and we develop the quantum
field theory of the gravitational waves in the F, P, L, and R regions. We
demonstrate that the mode functions of the quantized gravitational waves in the
left and right Rindler wedges are obtained by an analytic continuation of the
left-moving and right-moving wave modes in Kasner spacetime. On the basis of
these analyses, we discuss the Unruh effect of quantized gravitational waves
for an observer in a uniformly accelerated motion in Minkowski spacetime.
| [
{
"created": "Wed, 30 Dec 2020 02:00:57 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Jan 2021 08:54:47 GMT",
"version": "v2"
},
{
"created": "Thu, 8 Apr 2021 02:58:05 GMT",
"version": "v3"
}
] | 2021-04-14 | [
[
"Sugiyama",
"Yuuki",
""
],
[
"Yamamoto",
"Kazuhiro",
""
],
[
"Kobayashi",
"Tsutomu",
""
]
] | We derive the solutions of gravitational waves in the future (F) expanding and the past (P) shrinking Kanser spacetimes as well as in the left (L) and right (R) Rindler wedges in the Regge-Wheeler gauge. The solutions for all metric components are obtained in an analytic form in each region. We identify the master variables, which are equivalent to massless scalar fields, to describe the gravitational degrees of freedom for the odd parity and even parity modes under the transformation in the two-dimensional plane symmetric space. Then, the master variables are quantized, and we develop the quantum field theory of the gravitational waves in the F, P, L, and R regions. We demonstrate that the mode functions of the quantized gravitational waves in the left and right Rindler wedges are obtained by an analytic continuation of the left-moving and right-moving wave modes in Kasner spacetime. On the basis of these analyses, we discuss the Unruh effect of quantized gravitational waves for an observer in a uniformly accelerated motion in Minkowski spacetime. |
1212.6433 | Y. Jack Ng | Y. Jack Ng | MoNDian Dark Matter, Entropic Gravity, and Infinite Statistics | 4 pages; LaTex; talk at 13th Marcel Grossmann Meeting and at Miami
2012 Conference, based on recent work done with CM Ho and D Minic
(arXiv:1005.3537, 1105.2916, 1201.2365); a similar version will appear in the
Proceedings of the 13th Marcel Grossmann Meeting | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose the concept of MoNDian dark matter which behaves like cold dark
matter at cluster and cosmic scales but emulates modified Newtonian dynamics at
the galactic scale. The connection between global physics and local galactic
dynamics is implemented via entropic gravity. We also give an alternative
formulation of MoNDian dark matter by using an effective gravitational
Born-Infeld theory. In the latter approach, we show that the quanta of MoNDian
dark matter obey infinite statistics.
| [
{
"created": "Thu, 27 Dec 2012 21:14:13 GMT",
"version": "v1"
}
] | 2013-01-01 | [
[
"Ng",
"Y. Jack",
""
]
] | We propose the concept of MoNDian dark matter which behaves like cold dark matter at cluster and cosmic scales but emulates modified Newtonian dynamics at the galactic scale. The connection between global physics and local galactic dynamics is implemented via entropic gravity. We also give an alternative formulation of MoNDian dark matter by using an effective gravitational Born-Infeld theory. In the latter approach, we show that the quanta of MoNDian dark matter obey infinite statistics. |
0808.3337 | Sergey Kozyrev | S.N. Andrianov, V.V. Bochkarev, S.M. Kozyrev | Quantum equation of motion for a particle in the field of primordial
fluctuations | 8 pages, 3 figures | null | 10.1117/12.801754 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Brane model of universe is considered for a particle. Conservation laws
inside the brane are obtained. Equation of motion is derived for a particle
using variation principle from these conservation laws. This equation includes
terms accounting the variation of brane topology. Its solution is obtained at
some approximations and dispersion relation for a particle is derived.
| [
{
"created": "Mon, 25 Aug 2008 11:41:22 GMT",
"version": "v1"
}
] | 2009-11-13 | [
[
"Andrianov",
"S. N.",
""
],
[
"Bochkarev",
"V. V.",
""
],
[
"Kozyrev",
"S. M.",
""
]
] | Brane model of universe is considered for a particle. Conservation laws inside the brane are obtained. Equation of motion is derived for a particle using variation principle from these conservation laws. This equation includes terms accounting the variation of brane topology. Its solution is obtained at some approximations and dispersion relation for a particle is derived. |
1510.01911 | Filip Hejda | Ji\v{r}\'i Bi\v{c}\'ak and Filip Hejda | Near-horizon description of extremal magnetised stationary black holes
and Meissner effect | Added one reference and some details to fit the journal version | Phys. Rev. D 92, 104006 (2015) | 10.1103/PhysRevD.92.104006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | After a brief summary of the basic properties of stationary spacetimes
representing rotating, charged black holes in strong axisymmetric magnetic
fields, we concentrate on extremal cases, for which the horizon surface gravity
vanishes. We investigate their properties by constructing simpler spacetimes
that exhibit their geometries near degenerate horizons. Starting from the
symmetry arguments we find that the near-horizon geometries of extremal
magnetised Kerr-Newman black holes can be characterised by just one
dimensionless parameter: "effective Kerr-Newman mixing angle". Employing the
near-horizon geometries we demonstrate the Meissner effect of magnetic field
expulsion from extremal black holes.
| [
{
"created": "Wed, 7 Oct 2015 12:07:25 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Nov 2015 10:49:47 GMT",
"version": "v2"
}
] | 2015-11-06 | [
[
"Bičák",
"Jiří",
""
],
[
"Hejda",
"Filip",
""
]
] | After a brief summary of the basic properties of stationary spacetimes representing rotating, charged black holes in strong axisymmetric magnetic fields, we concentrate on extremal cases, for which the horizon surface gravity vanishes. We investigate their properties by constructing simpler spacetimes that exhibit their geometries near degenerate horizons. Starting from the symmetry arguments we find that the near-horizon geometries of extremal magnetised Kerr-Newman black holes can be characterised by just one dimensionless parameter: "effective Kerr-Newman mixing angle". Employing the near-horizon geometries we demonstrate the Meissner effect of magnetic field expulsion from extremal black holes. |
2407.04750 | Nivaldo Agostinho Lemos | A. M. Silva, M. J. Rebou\c{c}as and N. A. Lemos | Violation of Causality in $f(Q)$ Gravity | 19 pages | null | null | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | There is ongoing interest in the nonmetricity formulation of gravity. The
nonlinear extension of the theory, called $f(Q)$ gravity, has recently been
proposed and offers a promising avenue for addressing some of the long-standing
challenges in cosmology and fundamental physics. A number of solutions have
already been found that have confirmed the usefulness of the theory for
astrophysics and cosmology. Motivated by earlier work on G\"odel-type
spacetimes, we investigate whether $f(Q)$ gravity admits cosmological solutions
that violate causality. We find that G\"odel-type metrics do not appear to be
compatible with this modified gravity theory unless it reduces to the trivial
case of symmetric teleparallel gravity, corresponding to $f(Q)=AQ+B$, which is
equivalent to general relativity. For $f(Q)$ more general than linear, the
theory seems endowed with some chronology protection mechanism that shields it
from G\"odel-like causality violations.
| [
{
"created": "Thu, 4 Jul 2024 22:09:57 GMT",
"version": "v1"
}
] | 2024-07-11 | [
[
"Silva",
"A. M.",
""
],
[
"Rebouças",
"M. J.",
""
],
[
"Lemos",
"N. A.",
""
]
] | There is ongoing interest in the nonmetricity formulation of gravity. The nonlinear extension of the theory, called $f(Q)$ gravity, has recently been proposed and offers a promising avenue for addressing some of the long-standing challenges in cosmology and fundamental physics. A number of solutions have already been found that have confirmed the usefulness of the theory for astrophysics and cosmology. Motivated by earlier work on G\"odel-type spacetimes, we investigate whether $f(Q)$ gravity admits cosmological solutions that violate causality. We find that G\"odel-type metrics do not appear to be compatible with this modified gravity theory unless it reduces to the trivial case of symmetric teleparallel gravity, corresponding to $f(Q)=AQ+B$, which is equivalent to general relativity. For $f(Q)$ more general than linear, the theory seems endowed with some chronology protection mechanism that shields it from G\"odel-like causality violations. |
1712.09706 | Viktor G. Czinner | Tam\'as S. Bir\'o, Viktor G. Czinner, Hideo Iguchi and P\'eter V\'an | Black hole horizons can hide positive heat capacity | 5 pages, no figures, to be published in Phys. Lett. B | Physics Letters B, V782:228-231, 2018 | 10.1016/j.physletb.2018.05.035 | null | gr-qc cond-mat.stat-mech hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Regarding the volume as independent thermodynamic variable we point out that
black hole horizons can hide positive heat capacity and specific heat. Such
horizons are mechanically marginal, but thermally stable. In the absence of a
canonical volume definition, we consider various suggestions scaling
differently with the horizon radius. Assuming Euler-homogeneity of the entropy,
besides the Hawking temperature, a pressure and a corresponding work term
render the equation of state at the horizon thermally stable for any meaningful
volume concept that scales larger than the horizon area. When considering also
a Stefan--Boltzmann radiation like equation of state at the horizon, only one
possible solution emerges: the Christodoulou--Rovelli volume, scaling as $V\sim
R^5$, with an entropy $S = \frac{8}{3}S_{BH}$.
| [
{
"created": "Wed, 27 Dec 2017 23:09:43 GMT",
"version": "v1"
},
{
"created": "Fri, 11 May 2018 14:18:30 GMT",
"version": "v2"
}
] | 2020-02-06 | [
[
"Biró",
"Tamás S.",
""
],
[
"Czinner",
"Viktor G.",
""
],
[
"Iguchi",
"Hideo",
""
],
[
"Ván",
"Péter",
""
]
] | Regarding the volume as independent thermodynamic variable we point out that black hole horizons can hide positive heat capacity and specific heat. Such horizons are mechanically marginal, but thermally stable. In the absence of a canonical volume definition, we consider various suggestions scaling differently with the horizon radius. Assuming Euler-homogeneity of the entropy, besides the Hawking temperature, a pressure and a corresponding work term render the equation of state at the horizon thermally stable for any meaningful volume concept that scales larger than the horizon area. When considering also a Stefan--Boltzmann radiation like equation of state at the horizon, only one possible solution emerges: the Christodoulou--Rovelli volume, scaling as $V\sim R^5$, with an entropy $S = \frac{8}{3}S_{BH}$. |
gr-qc/0701066 | Muhammad Sharif | Asghar Qadir and M. Sharif | The Relativistic Generalization of the Gravitational Force for Arbitrary
Spacetimes | 16 pages | NuovoCim.B107:1071-1083,1992 | 10.1007/BF02727045 | null | gr-qc | null | It has been suggested that re-expressing relativity in terms of forces could
provide fresh insights. The formalism developed for this purpose only applied
to static, or conformally static, space-times. Here we extend it to arbitrary
space-times. It is hoped that this formalism may lead to a workable definition
of mass and energy in relativity.
| [
{
"created": "Fri, 12 Jan 2007 08:05:03 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Qadir",
"Asghar",
""
],
[
"Sharif",
"M.",
""
]
] | It has been suggested that re-expressing relativity in terms of forces could provide fresh insights. The formalism developed for this purpose only applied to static, or conformally static, space-times. Here we extend it to arbitrary space-times. It is hoped that this formalism may lead to a workable definition of mass and energy in relativity. |
2305.08163 | Hoang Nguyen | Hoang Ky Nguyen | Buchdahl-inspired spacetimes and wormholes: Unearthing Hans Buchdahl's
other 'hidden' treasure trove | Honorable Mention -- 2023 GRF Awards for Essays on Gravitation.
Accepted for publishing in Oct 2023 Special Issue of Int.J.Mod.Phys.D | Int. J. Mod. Phys. D (2023) 2342007 | 10.1142/S0218271823420075 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Circa 1962 Hans A. Buchdahl pioneered a program -- and made significant
progress -- seeking vacuo configurations in pure $\mathcal{R}^{2}$ gravity [H.
A. Buchdahl, Nuovo Cimento 23, 141 (1962)]. Unfortunately, he deemed the final
step in his calculations impassable and prematurely suspended his pursuit.
Since then, his achievements on this front have faded into dormancy.
Unbeknownst to Buchdahl himself, the $\mathcal{R}^{2}$ vacua that he sought
were within $\textit{his}$ striking distance. In our recent three-paper body of
work published in Phys. Rev. D, we broke this six-decades-old impasse and
accomplished his goal: A novel class of metrics, describing non-Schwarzschild
spacetimes in quadratic gravity and carrying a hallmark of higher-derivative
characteristic. Intriguing properties of Buchdahl-inspired spacetimes and their
associated Morris-Thorne-Buchdahl wormholes -- summarized herein -- embody a
new branch of phenomenology that transcends the Einstein-Hilbert paradigm.
| [
{
"created": "Sun, 14 May 2023 14:21:58 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Jun 2023 05:16:58 GMT",
"version": "v2"
}
] | 2023-10-31 | [
[
"Nguyen",
"Hoang Ky",
""
]
] | Circa 1962 Hans A. Buchdahl pioneered a program -- and made significant progress -- seeking vacuo configurations in pure $\mathcal{R}^{2}$ gravity [H. A. Buchdahl, Nuovo Cimento 23, 141 (1962)]. Unfortunately, he deemed the final step in his calculations impassable and prematurely suspended his pursuit. Since then, his achievements on this front have faded into dormancy. Unbeknownst to Buchdahl himself, the $\mathcal{R}^{2}$ vacua that he sought were within $\textit{his}$ striking distance. In our recent three-paper body of work published in Phys. Rev. D, we broke this six-decades-old impasse and accomplished his goal: A novel class of metrics, describing non-Schwarzschild spacetimes in quadratic gravity and carrying a hallmark of higher-derivative characteristic. Intriguing properties of Buchdahl-inspired spacetimes and their associated Morris-Thorne-Buchdahl wormholes -- summarized herein -- embody a new branch of phenomenology that transcends the Einstein-Hilbert paradigm. |
2010.15842 | Pau Amaro Seoane | Alejandro Torres-Orjuela, Pau Amaro Seoane, Zeyuan Xuan, Alvin J. K.
Chua, Mar\'ia J. B. Rosell and Xian Chen | Exciting modes due to the aberration of gravitational waves:
Measurability for extreme-mass-ratio inspirals | Accepted PRL | Phys. Rev. Lett. 127, 041102 (2021) | 10.1103/PhysRevLett.127.041102 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waves from a source moving relative to us can suffer from
special-relativistic effects such as aberration. The required velocities for
these to be significant are on the order of $1000\,\textrm{km s}^{-1}$. This
value corresponds to the velocity dispersion that one finds in clusters of
galaxies. Hence, we expect a large number of gravitational-wave sources to have
such effects imprinted in their signals. In particular, the signal from a
moving source will have its higher modes excited, i.e., $(3,3)$ and beyond. We
derive expressions describing this effect, and study its measurability for the
specific case of a circular, non-spinning extreme-mass-ratio inspiral. We find
that the excitation of higher modes by a peculiar velocity of
$1000\,\textrm{km\,s}^{-1}$ is detectable for such inspirals with
signal-to-noise ratios of $\gtrsim20$. Using a Fisher matrix analysis, we show
that the velocity of the source can be measured to a precision of just a few
percent for a signal-to-noise ratio of 100. If the motion of the source is
ignored parameter estimates could be biased, e.g., the estimated masses of the
components through a Doppler shift. Conversely, by including this effect in
waveform models, we could measure the velocity dispersion of clusters of
galaxies at distances inaccessible to light.
| [
{
"created": "Thu, 29 Oct 2020 18:00:02 GMT",
"version": "v1"
},
{
"created": "Sun, 11 Jul 2021 14:39:42 GMT",
"version": "v2"
}
] | 2021-07-28 | [
[
"Torres-Orjuela",
"Alejandro",
""
],
[
"Seoane",
"Pau Amaro",
""
],
[
"Xuan",
"Zeyuan",
""
],
[
"Chua",
"Alvin J. K.",
""
],
[
"Rosell",
"María J. B.",
""
],
[
"Chen",
"Xian",
""
]
] | Gravitational waves from a source moving relative to us can suffer from special-relativistic effects such as aberration. The required velocities for these to be significant are on the order of $1000\,\textrm{km s}^{-1}$. This value corresponds to the velocity dispersion that one finds in clusters of galaxies. Hence, we expect a large number of gravitational-wave sources to have such effects imprinted in their signals. In particular, the signal from a moving source will have its higher modes excited, i.e., $(3,3)$ and beyond. We derive expressions describing this effect, and study its measurability for the specific case of a circular, non-spinning extreme-mass-ratio inspiral. We find that the excitation of higher modes by a peculiar velocity of $1000\,\textrm{km\,s}^{-1}$ is detectable for such inspirals with signal-to-noise ratios of $\gtrsim20$. Using a Fisher matrix analysis, we show that the velocity of the source can be measured to a precision of just a few percent for a signal-to-noise ratio of 100. If the motion of the source is ignored parameter estimates could be biased, e.g., the estimated masses of the components through a Doppler shift. Conversely, by including this effect in waveform models, we could measure the velocity dispersion of clusters of galaxies at distances inaccessible to light. |
2012.05642 | Yaser Tavakoli | Yaser Tavakoli, Ahad K. Ardabili, Paulo Vargas Moniz | Exploring the cosmic censorship conjecture with a Gauss-Bonnet sector | 14 pages, 4 figures (Version accepted in PRD) | Phys. Rev. D 103, 084039 (2021) | 10.1103/PhysRevD.103.084039 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Dvali-Gabadadze-Porrati (DGP) braneworld model is employed to study the
gravitational collapse of dust, with a Gauss-Bonnet (GB) term present in the
five-dimensional bulk. We find that, within the normal (nonself-accelerating)
DGP branch and due to the curvature effects from the GB component on the brane,
the black hole singularity acquires modified features. More precisely, during
collapse and for a finite comoving time, before a singularity would emerge at
the zero physical radius, the first time derivative of the Hubble rate
diverges, whereas the brane energy density and the Hubble rate remain finite.
This is a peculiar behavior which displays similar properties to the sudden
singularity occurring in particular late-time cosmological frameworks.
Furthermore, the question of whether this altered singularity can be viewed by
an external observer or will be hidden by a black hole horizon is addressed. We
establish that, depending on the given induced-gravity parameter and the GB
coupling constant, there exists a {\em threshold mass} for the collapsing dust,
below which no trapped surfaces evolve as the collapse proceeds toward the
singularity. In other words, a {\em naked sudden singularity} may form.
| [
{
"created": "Thu, 10 Dec 2020 13:02:28 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Apr 2021 22:47:00 GMT",
"version": "v2"
}
] | 2021-04-27 | [
[
"Tavakoli",
"Yaser",
""
],
[
"Ardabili",
"Ahad K.",
""
],
[
"Moniz",
"Paulo Vargas",
""
]
] | The Dvali-Gabadadze-Porrati (DGP) braneworld model is employed to study the gravitational collapse of dust, with a Gauss-Bonnet (GB) term present in the five-dimensional bulk. We find that, within the normal (nonself-accelerating) DGP branch and due to the curvature effects from the GB component on the brane, the black hole singularity acquires modified features. More precisely, during collapse and for a finite comoving time, before a singularity would emerge at the zero physical radius, the first time derivative of the Hubble rate diverges, whereas the brane energy density and the Hubble rate remain finite. This is a peculiar behavior which displays similar properties to the sudden singularity occurring in particular late-time cosmological frameworks. Furthermore, the question of whether this altered singularity can be viewed by an external observer or will be hidden by a black hole horizon is addressed. We establish that, depending on the given induced-gravity parameter and the GB coupling constant, there exists a {\em threshold mass} for the collapsing dust, below which no trapped surfaces evolve as the collapse proceeds toward the singularity. In other words, a {\em naked sudden singularity} may form. |
2004.01662 | Tao Zhu | Cheng Liu, Tao Zhu, and Qiang Wu | Thin Accretion Disk around a four-dimensional Einstein-Gauss-Bonnet
Black Hole | 7 pages, 5 figures; V2: references added and some typos are
corrected; v3: 10 pages, 6 figures, version to appear in Chinese Physics C | Chinese Physics C Vol. 45, No. 1 (2021) 015105 | 10.1088/1674-1137/abc16c | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently a novel four-dimensional Einstein-Gauss-Bonnet (4EGB) theory of
gravity was proposed by Glavan and Lin [D. Glavan and C. Lin, Phys. Rev. Lett.
124, 081301 (2020)] which includes a regularized Gauss-Bonnet term by using the
re-scaling of the Gauss-Bonnet coupling constant $\alpha \to \alpha/(D-4)$ in
the limit $D\to 4$. This theory also has been reformulated to a specific class
of the Horndeski theory with an additional scalar degree of freedom and to a
spatial covariant version with a Lagrangian multiplier that can eliminate the
scalar mode. Here we study the physical properties of the electromagnetic
radiation emitted from a thin accretion disk around the static spherically
symmetric black hole in the 4EGB gravity. For this purpose, we assume the disk
is in a steady-state and in hydrodynamic and thermodynamic equilibrium so that
the emitted electromagnetic radiation is a black body spectrum. We study in
detail the effects of the Gauss-Bonnet coupling constant $\alpha$ in 4EGB
gravity on the energy flux, temperature distribution, and electromagnetic
spectrum of the disk. It is shown that with the increases of the parameter
$\alpha$, the energy flux, temperature distribution, and electromagnetic
spectrum of the accretion disk all increase. Besides, we also show that the
accretion efficiency increases as the growth of the parameter $\alpha$. Our
results indicate that the thin accretion disk around the static spherically
symmetric black hole in the 4EGB gravity is hotter, more luminosity, and more
efficient than that around a Schwarzschild black hole with the same mass for a
positive $\alpha$, while it is cooler, less luminosity, and less efficient for
a negative $\alpha$.
| [
{
"created": "Fri, 3 Apr 2020 16:29:22 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Apr 2020 13:59:40 GMT",
"version": "v2"
},
{
"created": "Wed, 9 Sep 2020 05:50:29 GMT",
"version": "v3"
}
] | 2021-01-01 | [
[
"Liu",
"Cheng",
""
],
[
"Zhu",
"Tao",
""
],
[
"Wu",
"Qiang",
""
]
] | Recently a novel four-dimensional Einstein-Gauss-Bonnet (4EGB) theory of gravity was proposed by Glavan and Lin [D. Glavan and C. Lin, Phys. Rev. Lett. 124, 081301 (2020)] which includes a regularized Gauss-Bonnet term by using the re-scaling of the Gauss-Bonnet coupling constant $\alpha \to \alpha/(D-4)$ in the limit $D\to 4$. This theory also has been reformulated to a specific class of the Horndeski theory with an additional scalar degree of freedom and to a spatial covariant version with a Lagrangian multiplier that can eliminate the scalar mode. Here we study the physical properties of the electromagnetic radiation emitted from a thin accretion disk around the static spherically symmetric black hole in the 4EGB gravity. For this purpose, we assume the disk is in a steady-state and in hydrodynamic and thermodynamic equilibrium so that the emitted electromagnetic radiation is a black body spectrum. We study in detail the effects of the Gauss-Bonnet coupling constant $\alpha$ in 4EGB gravity on the energy flux, temperature distribution, and electromagnetic spectrum of the disk. It is shown that with the increases of the parameter $\alpha$, the energy flux, temperature distribution, and electromagnetic spectrum of the accretion disk all increase. Besides, we also show that the accretion efficiency increases as the growth of the parameter $\alpha$. Our results indicate that the thin accretion disk around the static spherically symmetric black hole in the 4EGB gravity is hotter, more luminosity, and more efficient than that around a Schwarzschild black hole with the same mass for a positive $\alpha$, while it is cooler, less luminosity, and less efficient for a negative $\alpha$. |
2402.18022 | Diogo Bragan\c{c}a | Diogo P. L. Bragan\c{c}a | Gravitational Repulsion in an Expanding Ball of Dust | 8 pages, 2 figures. Accepted for publication in Class. Quantum Grav | null | 10.1088/1361-6382/ad2d70 | null | gr-qc astro-ph.CO astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In general relativity, there is a velocity dependent term in the
gravitational acceleration of a test particle for an observer at infinity.
Depending on the direction of motion and the speed, that term can be repulsive.
We show that this is also the case in the Parametrized Post-Newtonian (PPN)
formalism. We compute the magnitude of that repulsive term for an expanding
sphere of dust observed at infinity, and find that it could mimic the effect of
a cosmological constant. The time evolution of such an expanding ball of dust
for an observer at infinity is calculated, and compared with the standard
$\Lambda$CDM model. We find that the so-called coincidence problem does not
exist for such a model as the energy density attributed to the expansion is
always of the same order as the matter energy density.
| [
{
"created": "Wed, 28 Feb 2024 03:36:43 GMT",
"version": "v1"
}
] | 2024-02-29 | [
[
"Bragança",
"Diogo P. L.",
""
]
] | In general relativity, there is a velocity dependent term in the gravitational acceleration of a test particle for an observer at infinity. Depending on the direction of motion and the speed, that term can be repulsive. We show that this is also the case in the Parametrized Post-Newtonian (PPN) formalism. We compute the magnitude of that repulsive term for an expanding sphere of dust observed at infinity, and find that it could mimic the effect of a cosmological constant. The time evolution of such an expanding ball of dust for an observer at infinity is calculated, and compared with the standard $\Lambda$CDM model. We find that the so-called coincidence problem does not exist for such a model as the energy density attributed to the expansion is always of the same order as the matter energy density. |
1003.5532 | Hubert F M Goenner | Hubert F M Goenner | Palatini's cousin: A New Variational Principle | 12 pages | Phys.Rev.D81:124019,2010 | 10.1103/PhysRevD.81.124019 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A variational principle is suggested within Riemannnian geometry, in which an
auxiliary metric and the Levi Civita connection are varied independently. The
auxiliary metric plays the role of a Lagrange multiplier and introduces
non-minimal coupling of matter to the curvature scalar. The field equations are
2nd order PDEs and easier to handle than those following from the so-called
Palatini method. Moreover, in contrast to the latter method. no gradients of
the matter variables appear. In cosmological modeling, the physics resulting
from the new variational principle will differ from the modeling using the
Palatini method.
| [
{
"created": "Mon, 29 Mar 2010 13:16:52 GMT",
"version": "v1"
}
] | 2014-11-20 | [
[
"Goenner",
"Hubert F M",
""
]
] | A variational principle is suggested within Riemannnian geometry, in which an auxiliary metric and the Levi Civita connection are varied independently. The auxiliary metric plays the role of a Lagrange multiplier and introduces non-minimal coupling of matter to the curvature scalar. The field equations are 2nd order PDEs and easier to handle than those following from the so-called Palatini method. Moreover, in contrast to the latter method. no gradients of the matter variables appear. In cosmological modeling, the physics resulting from the new variational principle will differ from the modeling using the Palatini method. |
2104.15011 | Matthew Mould | Matthew Mould | Unstable binary black-hole spins: post-Newtonian theory and numerical
relativity | 4 pages, 2 figures, contribution to the 2021 Gravitation session of
the 55th Rencontres de Moriond | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spin precession occurs in binary black holes whose spins are misaligned with
the orbital angular momentum. Otherwise, the spin configuration is constant and
the subsequent binary dynamics and gravitational-wave emission are much
simpler. We summarize a series of works which has shown that, while three of
the aligned configurations are stable equilibria, the `up-down' configuration,
in which the heavier (lighter) black hole is (anti) aligned with the orbital
angular momentum, is unstable when perturbed; at a critical point in the
inspiral the black hole spins begin to tilt wildly as precession takes over. We
present two equivalent approaches to derive the instability onset based on
multitimescale post-Newtonian techniques, and point out that the instability
has a predictable endpoint. Finally, we demonstrate the presence of this
precessional instability in the strong-field regime of numerical relativity
with simulations of aligned-spin binaries lasting $\sim100$ orbits before
merger. The spins of up-down systems can tilt by $\sim90^\circ$, leaving a
notable imprint in the emitted gravitational-wave signals and providing a
possible mechanism to form precessing systems in astrophysical environments
from which sources are preferentially born with (anti) aligned spins.
| [
{
"created": "Fri, 30 Apr 2021 13:59:19 GMT",
"version": "v1"
}
] | 2021-05-03 | [
[
"Mould",
"Matthew",
""
]
] | Spin precession occurs in binary black holes whose spins are misaligned with the orbital angular momentum. Otherwise, the spin configuration is constant and the subsequent binary dynamics and gravitational-wave emission are much simpler. We summarize a series of works which has shown that, while three of the aligned configurations are stable equilibria, the `up-down' configuration, in which the heavier (lighter) black hole is (anti) aligned with the orbital angular momentum, is unstable when perturbed; at a critical point in the inspiral the black hole spins begin to tilt wildly as precession takes over. We present two equivalent approaches to derive the instability onset based on multitimescale post-Newtonian techniques, and point out that the instability has a predictable endpoint. Finally, we demonstrate the presence of this precessional instability in the strong-field regime of numerical relativity with simulations of aligned-spin binaries lasting $\sim100$ orbits before merger. The spins of up-down systems can tilt by $\sim90^\circ$, leaving a notable imprint in the emitted gravitational-wave signals and providing a possible mechanism to form precessing systems in astrophysical environments from which sources are preferentially born with (anti) aligned spins. |
1410.6605 | Lorenzo De Vittori | Lorenzo De Vittori, Achamveedu Gopakumar, Anuradha Gupta, Philippe
Jetzer | Memory effect from spinning unbound binaries | 7 pages, 2 figures. To appear in the Proceedings of the 2014 Sant
Cugat Forum on Astrophysics. Astrophysics and Space Science Proceedings, ed.
C.Sopuerta (Berlin: Springer-Verlag) | null | 10.1007/978-3-319-10488-1_22 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a recently developed prescription to obtain ready-to-use
gravitational wave (GW) polarization states for spinning compact binaries on
hyperbolic orbits. We include leading order spin-orbit interactions, invoking
1.5PN-accurate quasi-Keplerian parametrization for the radial part of the
orbital dynamics. We also include radiation reaction effects on $h_+$ and
$h_{\times}$ during the interaction. In the GW signals from spinning binaries
there is evidence of the memory effect in both polarizations, in contrast to
the non-spinning case, where only the cross polarizations exhibits
non-vanishing amplitudes at infinite time. We also compute 1PN-accurate GW
polarization states for non-spinning compact binaries in unbound orbits in a
fully parametric way, and compare them with existing waveforms.
| [
{
"created": "Fri, 24 Oct 2014 07:54:03 GMT",
"version": "v1"
}
] | 2015-06-23 | [
[
"De Vittori",
"Lorenzo",
""
],
[
"Gopakumar",
"Achamveedu",
""
],
[
"Gupta",
"Anuradha",
""
],
[
"Jetzer",
"Philippe",
""
]
] | We present a recently developed prescription to obtain ready-to-use gravitational wave (GW) polarization states for spinning compact binaries on hyperbolic orbits. We include leading order spin-orbit interactions, invoking 1.5PN-accurate quasi-Keplerian parametrization for the radial part of the orbital dynamics. We also include radiation reaction effects on $h_+$ and $h_{\times}$ during the interaction. In the GW signals from spinning binaries there is evidence of the memory effect in both polarizations, in contrast to the non-spinning case, where only the cross polarizations exhibits non-vanishing amplitudes at infinite time. We also compute 1PN-accurate GW polarization states for non-spinning compact binaries in unbound orbits in a fully parametric way, and compare them with existing waveforms. |
2103.15707 | Luciano Combi | Luciano Combi, Federico G. Lopez Armengol, Manuela Campanelli, Brennan
Ireland, Scott C. Noble, Hiroyuki Nakano, Dennis Bowen | Superposed metric for spinning black hole binaries approaching merger | Accepted for publication in Physical Review D | Phys. Rev. D 104, 044041 (2021) | 10.1103/PhysRevD.104.044041 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We construct an approximate metric that represents the spacetime of spinning
binary black holes (BBH) approaching merger. We build the metric as an
analytical superposition of two Kerr metrics in harmonic coordinates, where we
transform each black hole term with time-dependent boosts describing an
inspiral trajectory. The velocities and trajectories of the boost are obtained
by solving the post-Newtonian (PN) equations of motion at 3.5 PN order. We
analyze the spacetime scalars of the new metric and we show that it is an
accurate approximation of Einstein's field equations in vacuum for a BBH system
in the inspiral regime. Furthermore, to prove the effectiveness of our
approach, we test the metric in the context of a 3D general relativistic
magneto-hydrodynamical (GRMHD) simulation of accreting mini-disks around the
black holes. We compare our results with a previous well-tested spacetime
construction based on the asymptotic matching method. We conclude that our new
spacetime is well-suited for long-term GRMHD simulations of spinning binary
black holes on their way to the merger.
| [
{
"created": "Mon, 29 Mar 2021 15:45:12 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Aug 2021 16:26:12 GMT",
"version": "v2"
}
] | 2021-08-25 | [
[
"Combi",
"Luciano",
""
],
[
"Armengol",
"Federico G. Lopez",
""
],
[
"Campanelli",
"Manuela",
""
],
[
"Ireland",
"Brennan",
""
],
[
"Noble",
"Scott C.",
""
],
[
"Nakano",
"Hiroyuki",
""
],
[
"Bowen",
"Dennis",
""
]
] | We construct an approximate metric that represents the spacetime of spinning binary black holes (BBH) approaching merger. We build the metric as an analytical superposition of two Kerr metrics in harmonic coordinates, where we transform each black hole term with time-dependent boosts describing an inspiral trajectory. The velocities and trajectories of the boost are obtained by solving the post-Newtonian (PN) equations of motion at 3.5 PN order. We analyze the spacetime scalars of the new metric and we show that it is an accurate approximation of Einstein's field equations in vacuum for a BBH system in the inspiral regime. Furthermore, to prove the effectiveness of our approach, we test the metric in the context of a 3D general relativistic magneto-hydrodynamical (GRMHD) simulation of accreting mini-disks around the black holes. We compare our results with a previous well-tested spacetime construction based on the asymptotic matching method. We conclude that our new spacetime is well-suited for long-term GRMHD simulations of spinning binary black holes on their way to the merger. |
1303.0939 | Miklos L{\aa}ngvik | Miklos L{\aa}ngvik | En komprimerad introduktion till slingkvantgravitation och spinnskum
modeller | 55 pages, 4 figures, review article, in Swedish | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A short introductory review of loop quantum gravity and spinfoam models in
Swedish. A small knowledge of general relativity in connection variables is
assumed, but an emphasis has been put on giving a self-supporting presentation.
--
Inom denna reviewarikel ser vi \"over slingkvantgravitationens och spinnskum
modellernas struktur och uppbyggnad. Artikeln g\"or sitt b\"asta f\"or att
f\"oruts\"atta s{\aa} lite f\"orkunskaper som m\"ojligt, men en viss k\"annedom
om allm\"an relativitet i konnektionsvariabler kan vara bra att ha.
| [
{
"created": "Tue, 5 Mar 2013 06:19:13 GMT",
"version": "v1"
}
] | 2013-03-06 | [
[
"Långvik",
"Miklos",
""
]
] | A short introductory review of loop quantum gravity and spinfoam models in Swedish. A small knowledge of general relativity in connection variables is assumed, but an emphasis has been put on giving a self-supporting presentation. -- Inom denna reviewarikel ser vi \"over slingkvantgravitationens och spinnskum modellernas struktur och uppbyggnad. Artikeln g\"or sitt b\"asta f\"or att f\"oruts\"atta s{\aa} lite f\"orkunskaper som m\"ojligt, men en viss k\"annedom om allm\"an relativitet i konnektionsvariabler kan vara bra att ha. |
1901.00676 | Andrea Geralico | Donato Bini, Andrea Geralico | Gravitational wave effects on astrometric observables | 15 pages, revtex macros; published version | Phys. Rev. D 98, 124036 (2018) | 10.1103/PhysRevD.98.124036 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Observational data from the ESA astrometric mission Gaia determining the
positions of celestial objects within an accuracy of few microarcseconds will
be soon fully available. Other satellite-based space missions are currently
planned to significantly improve such precision in the next years. The data
reduction process needs high-precision general relativistic models, allowing
one to solve the inverse ray-tracing problem in the gravitational field of the
Solar System up to the requested level of accuracy and leading then to the
estimate of astrometric parameters. Besides a satisfactory description of the
background field due to the planets (which should include their multipolar
structure), one should consider also other effects which may induce
modifications to the light propagation. For instance, the interaction of the
light signal with the superposed gravitational field of a gravitational wave
emitted by a distant source would cause a shift in the apparent positions of
the stars. We compute here the main astrometric observables needed for data
reduction of satellite-based missions in the presence of a passing plane
gravitational wave. We also take into account the effect of the mass quadrupole
moment of the planets, improving previous results obtained for Gaia.
| [
{
"created": "Thu, 3 Jan 2019 10:47:52 GMT",
"version": "v1"
}
] | 2019-01-04 | [
[
"Bini",
"Donato",
""
],
[
"Geralico",
"Andrea",
""
]
] | Observational data from the ESA astrometric mission Gaia determining the positions of celestial objects within an accuracy of few microarcseconds will be soon fully available. Other satellite-based space missions are currently planned to significantly improve such precision in the next years. The data reduction process needs high-precision general relativistic models, allowing one to solve the inverse ray-tracing problem in the gravitational field of the Solar System up to the requested level of accuracy and leading then to the estimate of astrometric parameters. Besides a satisfactory description of the background field due to the planets (which should include their multipolar structure), one should consider also other effects which may induce modifications to the light propagation. For instance, the interaction of the light signal with the superposed gravitational field of a gravitational wave emitted by a distant source would cause a shift in the apparent positions of the stars. We compute here the main astrometric observables needed for data reduction of satellite-based missions in the presence of a passing plane gravitational wave. We also take into account the effect of the mass quadrupole moment of the planets, improving previous results obtained for Gaia. |
2201.11072 | Gerardo Garc\'ia-Moreno | Carlos Barcel\'o, Jokin Eguia S\'anchez, Gerardo Garc\'ia-Moreno and
Gil Jannes | Chronology Protection Implementation in Analogue Gravity | 37 pages, 8 figures; v2: Minor changes introduced to match the
published version | Eur. Phys. J. C 82, 299 (2022) | 10.1140/epjc/s10052-022-10275-3 | null | gr-qc cond-mat.other hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Analogue gravity systems offer many insights into gravitational phenomena,
both at the classical and at the semiclassical level. The existence of an
underlying Minkowskian structure (or Galilean in the non-relativistic limit) in
the laboratory has been argued to directly forbid the simulation of geometries
with Closed Timelike Curves (CTCs) within analogue systems. We will show that
this is not strictly the case. In principle, it is possible to simulate
spacetimes with CTCs whenever this does not entail the presence of a
chronological horizon separating regions with CTCs from regions that do not
have CTCs. We find an Analogue-gravity Chronology protection mechanism very
similar in spirit to Hawking's Chronology Protection hypothesis. We identify
the universal behaviour of analogue systems near the formation of such horizons
and discuss the further implications that this analysis has from an emergent
gravity perspective. Furthermore, we build explicit geometries containing CTCs,
for instance spacetimes constructed from two warp-drive configurations, that
might be useful for future analysis, both from a theoretical and an
experimental point of view.
| [
{
"created": "Wed, 26 Jan 2022 17:32:32 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Apr 2022 08:13:08 GMT",
"version": "v2"
}
] | 2022-04-08 | [
[
"Barceló",
"Carlos",
""
],
[
"Sánchez",
"Jokin Eguia",
""
],
[
"García-Moreno",
"Gerardo",
""
],
[
"Jannes",
"Gil",
""
]
] | Analogue gravity systems offer many insights into gravitational phenomena, both at the classical and at the semiclassical level. The existence of an underlying Minkowskian structure (or Galilean in the non-relativistic limit) in the laboratory has been argued to directly forbid the simulation of geometries with Closed Timelike Curves (CTCs) within analogue systems. We will show that this is not strictly the case. In principle, it is possible to simulate spacetimes with CTCs whenever this does not entail the presence of a chronological horizon separating regions with CTCs from regions that do not have CTCs. We find an Analogue-gravity Chronology protection mechanism very similar in spirit to Hawking's Chronology Protection hypothesis. We identify the universal behaviour of analogue systems near the formation of such horizons and discuss the further implications that this analysis has from an emergent gravity perspective. Furthermore, we build explicit geometries containing CTCs, for instance spacetimes constructed from two warp-drive configurations, that might be useful for future analysis, both from a theoretical and an experimental point of view. |
2006.06421 | Arun Mathew | Arun Mathew, Muhammed Shafeeque and Malay K. Nandy | Stellar structure of quark stars in a modified Starobinsky gravity | null | null | 10.1140/epjc/s10052-020-8130-4 | null | gr-qc astro-ph.CO astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a form of gravity-matter interaction given by $\omega RT$ in the
framework of $f(R,T)$ gravity and examine the effect of such interaction in
spherically symmetric compact stars. Treating the gravity-matter coupling as a
perturbative term on the background of Starobinsky gravity, we develop a
perturbation theory for equilibrium configurations. For illustration, we take
the case of quark stars and explore their various stellar properties. We find
that the gravity-matter coupling causes an increase in the stable maximal mass
which is relevant for recent observations on binary pulsars.
| [
{
"created": "Wed, 10 Jun 2020 08:02:58 GMT",
"version": "v1"
}
] | 2020-07-14 | [
[
"Mathew",
"Arun",
""
],
[
"Shafeeque",
"Muhammed",
""
],
[
"Nandy",
"Malay K.",
""
]
] | We propose a form of gravity-matter interaction given by $\omega RT$ in the framework of $f(R,T)$ gravity and examine the effect of such interaction in spherically symmetric compact stars. Treating the gravity-matter coupling as a perturbative term on the background of Starobinsky gravity, we develop a perturbation theory for equilibrium configurations. For illustration, we take the case of quark stars and explore their various stellar properties. We find that the gravity-matter coupling causes an increase in the stable maximal mass which is relevant for recent observations on binary pulsars. |
2303.09116 | Theodoros Nakas | Athanasios Bakopoulos, Theodoros Nakas | Novel exact ultra-compact and ultra-sparse hairy black holes emanating
from regular and phantom scalar fields | 23 pages, 6 figures, an Appendix added, typos corrected, matches
published version | null | 10.1103/PhysRevD.107.124035 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the framework of a simple gravitational theory that contains a scalar
field minimally coupled to gravity, we investigate the emergence of analytic
black-hole solutions with non-trivial scalar hair of secondary type. Although
it is possible for one to obtain asymptotically (A)dS solutions using our
setup, in the context of the present work, we are solely interested in
asymptotically flat solutions. At first, we study the properties of static and
spherically symmetric black-hole solutions emanating from both regular and
phantom scalar fields. We find that the regular-scalar-field-induced solutions
are solutions describing ultra-compact black holes, while the phantom scalar
fields generate ultra-sparse black-hole solutions. The latter are black holes
that can be potentially of very low density since, contrary to ultra-compact
ones, their horizon radius is always greater than the horizon radius of the
corresponding Schwarzschild black hole of the same mass. Then, we generalize
the above static solutions to slowly rotating ones and compute their angular
velocities explicitly. Finally, the study of the axial perturbations of the
derived solutions takes place, in which we show that there is always a region
in the parameter space of the free parameters of our theory that allows the
existence of both ultra-compact and ultra-sparse black holes.
| [
{
"created": "Thu, 16 Mar 2023 07:17:48 GMT",
"version": "v1"
},
{
"created": "Sat, 17 Jun 2023 19:09:13 GMT",
"version": "v2"
}
] | 2023-06-21 | [
[
"Bakopoulos",
"Athanasios",
""
],
[
"Nakas",
"Theodoros",
""
]
] | In the framework of a simple gravitational theory that contains a scalar field minimally coupled to gravity, we investigate the emergence of analytic black-hole solutions with non-trivial scalar hair of secondary type. Although it is possible for one to obtain asymptotically (A)dS solutions using our setup, in the context of the present work, we are solely interested in asymptotically flat solutions. At first, we study the properties of static and spherically symmetric black-hole solutions emanating from both regular and phantom scalar fields. We find that the regular-scalar-field-induced solutions are solutions describing ultra-compact black holes, while the phantom scalar fields generate ultra-sparse black-hole solutions. The latter are black holes that can be potentially of very low density since, contrary to ultra-compact ones, their horizon radius is always greater than the horizon radius of the corresponding Schwarzschild black hole of the same mass. Then, we generalize the above static solutions to slowly rotating ones and compute their angular velocities explicitly. Finally, the study of the axial perturbations of the derived solutions takes place, in which we show that there is always a region in the parameter space of the free parameters of our theory that allows the existence of both ultra-compact and ultra-sparse black holes. |
2003.02373 | Sizheng Ma | Sizheng Ma, Hang Yu, Yanbei Chen | Excitation of f-modes during mergers of spinning binary neutron star | null | Phys. Rev. D 101, 123020 (2020) | 10.1103/PhysRevD.101.123020 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Tidal effects have important imprints on gravitational waves (GWs) emitted
during the final stage of the coalescence of binaries that involve neutron
stars (NSs). Dynamical tides can be significant when NS oscillations become
resonant with orbital motion; understanding this process is important for
accurately modeling GW emission from these binaries, and for extracting NS
information from GW data. In this paper, we carry out a systematic study on the
tidal excitation of fundamental modes of spinning NSs in coalescencing
binaries, focusing on the case when the NS spin is anti-aligned with the
orbital angular momentum-where the tidal resonance is most likely to take
place. We first expand NS oscillations into stellar eigen-modes, and then
obtain a Hamiltonian that governs the tidally coupled orbit-mode evolution. We
next find a new approximation that can lead to analytic expressions of tidal
excitations to a high accuracy, and are valid in all regimes of the binary
evolution: adiabatic, resonant, and post-resonance. Using the method of
osculating orbits, we obtain semi-analytic approximations to the orbital
evolution and GW emission; their agreements with numerical results give us
confidence in on our understanding of the system's dynamics. In particular, we
recover both the averaged post-resonance evolution, which differs from the
pre-resonance point-particle orbit by shifts in orbital energy and angular
momentum, as well as instantaneous perturbations driven by the tidal motion.
Finally, we use the Fisher matrix technique to study the effect of dynamical
tides on parameter estimation. We find that the dynamical tides may potentially
provide an additional channel to study the physics of NSs. The method presented
in this paper is generic and not restricted to f mode; it can also be applied
to other types of tide.
| [
{
"created": "Wed, 4 Mar 2020 23:55:04 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Jun 2020 03:41:46 GMT",
"version": "v2"
}
] | 2020-06-19 | [
[
"Ma",
"Sizheng",
""
],
[
"Yu",
"Hang",
""
],
[
"Chen",
"Yanbei",
""
]
] | Tidal effects have important imprints on gravitational waves (GWs) emitted during the final stage of the coalescence of binaries that involve neutron stars (NSs). Dynamical tides can be significant when NS oscillations become resonant with orbital motion; understanding this process is important for accurately modeling GW emission from these binaries, and for extracting NS information from GW data. In this paper, we carry out a systematic study on the tidal excitation of fundamental modes of spinning NSs in coalescencing binaries, focusing on the case when the NS spin is anti-aligned with the orbital angular momentum-where the tidal resonance is most likely to take place. We first expand NS oscillations into stellar eigen-modes, and then obtain a Hamiltonian that governs the tidally coupled orbit-mode evolution. We next find a new approximation that can lead to analytic expressions of tidal excitations to a high accuracy, and are valid in all regimes of the binary evolution: adiabatic, resonant, and post-resonance. Using the method of osculating orbits, we obtain semi-analytic approximations to the orbital evolution and GW emission; their agreements with numerical results give us confidence in on our understanding of the system's dynamics. In particular, we recover both the averaged post-resonance evolution, which differs from the pre-resonance point-particle orbit by shifts in orbital energy and angular momentum, as well as instantaneous perturbations driven by the tidal motion. Finally, we use the Fisher matrix technique to study the effect of dynamical tides on parameter estimation. We find that the dynamical tides may potentially provide an additional channel to study the physics of NSs. The method presented in this paper is generic and not restricted to f mode; it can also be applied to other types of tide. |
1602.07198 | Subenoy Chakraborty | Sanjukta Chakraborty and Subenoy Chakraborty | Gravitational collapse of cylindrical anisotropic fluid: A source of
gravitational waves | 9 pages, No figures | General Relativity and Gravitation, Volume 46, 1784 (2014) | 10.1007/s10714-014-1784-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The present work deals with dynamics of gravitational collapse with
cylindrical symmetry as developed by Misner and Sharp. The interior collapsing
anisotropic cylindrical perfect fluid is matched to an exterior vacuum
cylindrically symmetric space-time due to Einstein--Rosen using the Darmois
matching conditions. It is found that the radial pressure of the anisotropic
perfect fluid is non-zero on the boundary surface and is related to the
components of shear viscosity. As a result, there is formation of gravitational
waves outside the collapsing matter.
| [
{
"created": "Fri, 19 Feb 2016 04:37:20 GMT",
"version": "v1"
},
{
"created": "Sat, 5 Mar 2016 09:39:46 GMT",
"version": "v2"
}
] | 2016-03-08 | [
[
"Chakraborty",
"Sanjukta",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | The present work deals with dynamics of gravitational collapse with cylindrical symmetry as developed by Misner and Sharp. The interior collapsing anisotropic cylindrical perfect fluid is matched to an exterior vacuum cylindrically symmetric space-time due to Einstein--Rosen using the Darmois matching conditions. It is found that the radial pressure of the anisotropic perfect fluid is non-zero on the boundary surface and is related to the components of shear viscosity. As a result, there is formation of gravitational waves outside the collapsing matter. |
2407.20032 | Nigel Bishop | Nigel T. Bishop | The interaction between gravitational waves and a viscous fluid shell on
a Schwarzschild background | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | Previous work has shown that the interaction between gravitational waves
(GWs) and a shell of viscous matter leads to damping of the GWs and heating of
the matter, and that these effects may be astrophysically significant. This
result was derived using the theory of linear perturbations about a Minkowki
background, and in this work the model is extended to be more physically
realistic by allowing the background geometry to be Schwarzschild. It is found
that the difference between using a Schwarzschild or Minkowski background is
minimal when either $r\gg M$ or $\lambda< M$, where $r$ is the radius of the
shell, $\lambda$ is the GW wavelength and $M$ is the mass of the system in
geometric units (so that $1M_\odot=1.48$km). However, when $r\sim 6M$ and
$\lambda\sim 25M$, then the damping and heating effects are about 9 times
larger on a Schwarzschild background than on Minkowski, and such situations
occur astrophysically.
| [
{
"created": "Mon, 29 Jul 2024 14:18:44 GMT",
"version": "v1"
}
] | 2024-07-30 | [
[
"Bishop",
"Nigel T.",
""
]
] | Previous work has shown that the interaction between gravitational waves (GWs) and a shell of viscous matter leads to damping of the GWs and heating of the matter, and that these effects may be astrophysically significant. This result was derived using the theory of linear perturbations about a Minkowki background, and in this work the model is extended to be more physically realistic by allowing the background geometry to be Schwarzschild. It is found that the difference between using a Schwarzschild or Minkowski background is minimal when either $r\gg M$ or $\lambda< M$, where $r$ is the radius of the shell, $\lambda$ is the GW wavelength and $M$ is the mass of the system in geometric units (so that $1M_\odot=1.48$km). However, when $r\sim 6M$ and $\lambda\sim 25M$, then the damping and heating effects are about 9 times larger on a Schwarzschild background than on Minkowski, and such situations occur astrophysically. |
1409.7874 | Sunil Maharaj | Sushant G. Ghosh and Sunil D. Maharaj | Cloud of strings for radiating black holes in Lovelock gravity | 9 pages, To appear in Phys. Rev. D | Phys. Rev. D 89, 084027 (2014) | 10.1103/PhysRevD.89.084027 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present exact spherically symmetric null dust solutions in the third order
Lovelock gravity with a string cloud background in arbitrary $N$ dimensions,.
This represents radiating black holes and generalizes the well known Vaidya
solution to Lovelock gravity with a string cloud in the background. We also
discuss the energy conditions and horizon structures, and explicitly bring out
the effect of the string clouds on the horizon structure of black hole
solutions for the higher dimensional general relativity and
Einstein-Gauss-Bonnet theories. It turns out that the presence of the coupling
constant of the Gauss-Bonnet terms and/or background string clouds completely
changes the structure of the horizon and this may lead to a naked singularity.
We recover known spherically symmetric radiating models as well as static black
holes in the appropriate limits.
| [
{
"created": "Sun, 28 Sep 2014 07:41:22 GMT",
"version": "v1"
}
] | 2015-06-23 | [
[
"Ghosh",
"Sushant G.",
""
],
[
"Maharaj",
"Sunil D.",
""
]
] | We present exact spherically symmetric null dust solutions in the third order Lovelock gravity with a string cloud background in arbitrary $N$ dimensions,. This represents radiating black holes and generalizes the well known Vaidya solution to Lovelock gravity with a string cloud in the background. We also discuss the energy conditions and horizon structures, and explicitly bring out the effect of the string clouds on the horizon structure of black hole solutions for the higher dimensional general relativity and Einstein-Gauss-Bonnet theories. It turns out that the presence of the coupling constant of the Gauss-Bonnet terms and/or background string clouds completely changes the structure of the horizon and this may lead to a naked singularity. We recover known spherically symmetric radiating models as well as static black holes in the appropriate limits. |
1703.10241 | Federico Le\'on Carrasco | Federico Carrasco and Oscar Reula | A novel scheme for simulating the force-free equations: boundary
conditions and the evolution of solutions towards stationarity | 18 pages, 17 figures | Phys. Rev. D 96, 063006 (2017) | 10.1103/PhysRevD.96.063006 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Force-Free Electrodynamics (FFE) describes a particular regime of
magnetically dominated relativistic plasmas, which arises on several
astrophysical scenarios of interest such as pulsars or active galactic nuclei.
In this article, we present a full 3D numerical implementation of the FFE
evolution around a Kerr black hole. The novelty of our approach is
three-folded: i) We use the "multi-block" technique to represent a domain with
$S^2 \times \mathbb{R}^{+}$ topology within a stable finite-differences scheme.
ii) We employ as evolution equations those arising from a covariant
hyperbolization of the FFE system. iii) We implement stable and
constraint-preserving boundary conditions to represent an outer region given by
a uniform magnetic field aligned or misaligned respect to the symmetry axis.
We find stationary jet solutions which reach equilibrium --through boundary
conditions-- with the outer numerical surface. This is so, even when the outer
boundary is located very close to the central region (i.e. $r_{out}\sim 10M $).
These numerical solutions reproduce most of the known results for analogue
astrophysical settings.
| [
{
"created": "Wed, 29 Mar 2017 20:40:26 GMT",
"version": "v1"
}
] | 2017-09-20 | [
[
"Carrasco",
"Federico",
""
],
[
"Reula",
"Oscar",
""
]
] | Force-Free Electrodynamics (FFE) describes a particular regime of magnetically dominated relativistic plasmas, which arises on several astrophysical scenarios of interest such as pulsars or active galactic nuclei. In this article, we present a full 3D numerical implementation of the FFE evolution around a Kerr black hole. The novelty of our approach is three-folded: i) We use the "multi-block" technique to represent a domain with $S^2 \times \mathbb{R}^{+}$ topology within a stable finite-differences scheme. ii) We employ as evolution equations those arising from a covariant hyperbolization of the FFE system. iii) We implement stable and constraint-preserving boundary conditions to represent an outer region given by a uniform magnetic field aligned or misaligned respect to the symmetry axis. We find stationary jet solutions which reach equilibrium --through boundary conditions-- with the outer numerical surface. This is so, even when the outer boundary is located very close to the central region (i.e. $r_{out}\sim 10M $). These numerical solutions reproduce most of the known results for analogue astrophysical settings. |
1003.1471 | Pavel Sl\'adek | Pavel Sladek, Daniel J. Finley | Asymptotic properties of the C-Metric | 28 pages, 11 figures | Class.Quant.Grav.27:205020,2010 | 10.1088/0264-9381/27/20/205020 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The aim of this article is to analyze the asymptotic properties of the
C-metric, using a general method specified in work of Tafel and coworkers, [1],
[2], [3]. By finding an appropriate conformal factor $\Omega$, it allows the
investigation of the asymptotic properties of a given asymptotically flat
spacetime. The news function and Bondi mass aspect are computed, their general
properties are analyzed, as well as the small mass, small acceleration, small
and large Bondi time limits.
| [
{
"created": "Sun, 7 Mar 2010 13:57:33 GMT",
"version": "v1"
}
] | 2014-11-20 | [
[
"Sladek",
"Pavel",
""
],
[
"Finley",
"Daniel J.",
""
]
] | The aim of this article is to analyze the asymptotic properties of the C-metric, using a general method specified in work of Tafel and coworkers, [1], [2], [3]. By finding an appropriate conformal factor $\Omega$, it allows the investigation of the asymptotic properties of a given asymptotically flat spacetime. The news function and Bondi mass aspect are computed, their general properties are analyzed, as well as the small mass, small acceleration, small and large Bondi time limits. |
1011.4127 | Tiberiu Harko | Z. Kovacs, T. Harko | Can accretion disk properties observationally distinguish black holes
from naked singularities? | 21 pages, 9 figures, accepted for publication in PRD | Phys.Rev.D82:124047,2010 | 10.1103/PhysRevD.82.124047 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Naked singularities are hypothetical astrophysical objects, characterized by
a gravitational singularity without an event horizon. Penrose has proposed a
conjecture, according to which there exists a cosmic censor who forbids the
occurrence of naked singularities. Distinguishing between astrophysical black
holes and naked singularities is a major challenge for present day
observational astronomy. A possibility of differentiating naked singularities
from black holes is through the comparative study of thin accretion disks
properties around rotating naked singularities and Kerr-type black holes,
respectively. In the present paper, we consider accretion disks around rotating
naked singularities, obtained as solutions of the field equations in the
Einstein-massless scalar field theory. A first major difference between
rotating naked singularities and Kerr black holes is in the frame dragging
effect, the angular velocity of a rotating naked singularity being inversely
proportional to its spin parameter. Due to the differences in the exterior
geometry, the thermodynamic and electromagnetic properties of the disks are
different for these two classes of compact objects, consequently giving clear
observational signatures that could discriminate between black holes and naked
singularities. For specific values of the spin parameter and of the scalar
charge, the energy flux from the disk around a rotating naked singularity can
exceed by several orders of magnitude the flux from the disk of a Kerr black
hole. The conversion efficiency of the accreting mass into radiation by
rotating naked singularities is always higher than the conversion efficiency
for black holes. Thus, these observational signatures may provide the necessary
tools from clearly distinguishing rotating naked singularities from Kerr-type
black holes.
| [
{
"created": "Thu, 18 Nov 2010 03:01:53 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Dec 2010 04:54:21 GMT",
"version": "v2"
}
] | 2011-01-17 | [
[
"Kovacs",
"Z.",
""
],
[
"Harko",
"T.",
""
]
] | Naked singularities are hypothetical astrophysical objects, characterized by a gravitational singularity without an event horizon. Penrose has proposed a conjecture, according to which there exists a cosmic censor who forbids the occurrence of naked singularities. Distinguishing between astrophysical black holes and naked singularities is a major challenge for present day observational astronomy. A possibility of differentiating naked singularities from black holes is through the comparative study of thin accretion disks properties around rotating naked singularities and Kerr-type black holes, respectively. In the present paper, we consider accretion disks around rotating naked singularities, obtained as solutions of the field equations in the Einstein-massless scalar field theory. A first major difference between rotating naked singularities and Kerr black holes is in the frame dragging effect, the angular velocity of a rotating naked singularity being inversely proportional to its spin parameter. Due to the differences in the exterior geometry, the thermodynamic and electromagnetic properties of the disks are different for these two classes of compact objects, consequently giving clear observational signatures that could discriminate between black holes and naked singularities. For specific values of the spin parameter and of the scalar charge, the energy flux from the disk around a rotating naked singularity can exceed by several orders of magnitude the flux from the disk of a Kerr black hole. The conversion efficiency of the accreting mass into radiation by rotating naked singularities is always higher than the conversion efficiency for black holes. Thus, these observational signatures may provide the necessary tools from clearly distinguishing rotating naked singularities from Kerr-type black holes. |
0712.2236 | Vitaly Vanchurin | Vitaly Vanchurin | Cosmic string loops: large and small, but not tiny | 6 pages, 1 figure, power-law approximation is replaced with
exponential | Phys.Rev.D77:063532,2008 | 10.1103/PhysRevD.77.063532 | LMU-ASC 78/07 | gr-qc astro-ph hep-ph hep-th | null | We develop an analytical model to study the production spectrum of loops in
the cosmic string network. In the scaling regime, we find two different scales
corresponding to large (one order below horizon) and small (few orders below
horizon) loops. The very small (tiny) loops at the gravitational back reaction
scale are absent, and thus, our model has no ultra-violet divergences. We
calculate the spectrum of loops and derive analytical expressions for the
positions and magnitudes of the small and large scale peaks. The small loops
are produced by large bursts of similar loops moving with very high velocities
in the same direction. We describe the shape of large loops, which would
usually consist of few kinks and few cusps per oscillation cycle. We also argue
that the typical size of large loops is set by the correlation length, which
does not depend on the intercommutation probability p, while the interstring
distance scales as p^{1/3}.
| [
{
"created": "Fri, 14 Dec 2007 19:08:31 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Mar 2008 19:01:33 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Vanchurin",
"Vitaly",
""
]
] | We develop an analytical model to study the production spectrum of loops in the cosmic string network. In the scaling regime, we find two different scales corresponding to large (one order below horizon) and small (few orders below horizon) loops. The very small (tiny) loops at the gravitational back reaction scale are absent, and thus, our model has no ultra-violet divergences. We calculate the spectrum of loops and derive analytical expressions for the positions and magnitudes of the small and large scale peaks. The small loops are produced by large bursts of similar loops moving with very high velocities in the same direction. We describe the shape of large loops, which would usually consist of few kinks and few cusps per oscillation cycle. We also argue that the typical size of large loops is set by the correlation length, which does not depend on the intercommutation probability p, while the interstring distance scales as p^{1/3}. |
1511.00358 | Kazunari Eda | Kazunari Eda, Kenji Ono, Yousuke Itoh | Determination of mass of an isolated neutron star using continuous
gravitational waves with two frequency modes: an effect of a misalignment
angle | 4 pages, 1 figure | null | 10.1088/1742-6596/716/1/012026 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A rapidly spinning neutron star (NS) would emit a continuous gravitational
wave (GW) detectable by the advanced LIGO, advanced Virgo, KAGRA and proposed
third generation detectors such as the Einstein Telescope (ET). Such a GW does
not propagate freely, but is affected by the Coulomb-type gravitational field
of the NS itself. This effect appears as a phase shift in the GW depending on
the NS mass. We have shown that mass of an isolated NS can, in principle, be
determined if we could detect the continuous GW with two or more frequency
modes. Indeed, our Monte Carlo simulations have demonstrated that mass of a NS
with its ellipticity $10^{-6}$ at 1 kpc is typically measurable with precision
of 20% using the ET, if the NS is precessing or has a pinned superfluid core
and emits GWs with once and twice the spin frequencies. After briefly
explaining our idea and results, this paper concerns with the effect of
misalignment angle ("wobble angle" in the case of a precessing NS) on the mass
measurement precision.
| [
{
"created": "Mon, 2 Nov 2015 02:20:32 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Feb 2016 15:09:53 GMT",
"version": "v2"
}
] | 2016-06-22 | [
[
"Eda",
"Kazunari",
""
],
[
"Ono",
"Kenji",
""
],
[
"Itoh",
"Yousuke",
""
]
] | A rapidly spinning neutron star (NS) would emit a continuous gravitational wave (GW) detectable by the advanced LIGO, advanced Virgo, KAGRA and proposed third generation detectors such as the Einstein Telescope (ET). Such a GW does not propagate freely, but is affected by the Coulomb-type gravitational field of the NS itself. This effect appears as a phase shift in the GW depending on the NS mass. We have shown that mass of an isolated NS can, in principle, be determined if we could detect the continuous GW with two or more frequency modes. Indeed, our Monte Carlo simulations have demonstrated that mass of a NS with its ellipticity $10^{-6}$ at 1 kpc is typically measurable with precision of 20% using the ET, if the NS is precessing or has a pinned superfluid core and emits GWs with once and twice the spin frequencies. After briefly explaining our idea and results, this paper concerns with the effect of misalignment angle ("wobble angle" in the case of a precessing NS) on the mass measurement precision. |
2112.12481 | Juan Calderon Bustillo | Juan Calder\'on Bustillo and Samson H.W. Leong and Koustav Chandra and
Barry McKernan and K. E. S. Ford | GW190521 as a black-hole merger coincident with the ZTF19abanrhr flare | 14 Pages, 11 Figures | null | null | LIGO-P2100467 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an analysis that reconciles the gravitational-wave signal GW190521
observed by the Advanced LIGO and Advanced Virgo detectors with the
electromagnetic flare ZTF19abanrhr observed by the Zwicky Transient Facility.
We analyze GW190521 under a mass-ratio prior uniform in $Q \in [1,4]$ and using
the state-of-the-art waveform model for black-hole mergers \texttt{NRSur7dq4}.
We find a $90\%$ credible region for the black-hole masses extending far
outside what originally reported by \cite{GW190521D}, where our maximum
likelihood masses reside. We find a $15\%$ probability that both black holes
avoid the pair-instability supernova gap. We infer a three-dimensional
sky-location highly consistent with ZTF19abanrhr, obtaining an odds-ratio
${\cal{O}}_{C/R}=72:1$ that strongly favors the hypothesis of a true
coincidence over a random one. Combining this event with the neutron-star
merger GW170817, we estimate a Hubble constant
H$_0=72.1^{+10.6}_{-6.4}\mathrm{km\,s^{-1}\,Mpc^{-1}}$ at the $68\%$ credible
level.
| [
{
"created": "Thu, 23 Dec 2021 12:13:06 GMT",
"version": "v1"
}
] | 2021-12-24 | [
[
"Bustillo",
"Juan Calderón",
""
],
[
"Leong",
"Samson H. W.",
""
],
[
"Chandra",
"Koustav",
""
],
[
"McKernan",
"Barry",
""
],
[
"Ford",
"K. E. S.",
""
]
] | We present an analysis that reconciles the gravitational-wave signal GW190521 observed by the Advanced LIGO and Advanced Virgo detectors with the electromagnetic flare ZTF19abanrhr observed by the Zwicky Transient Facility. We analyze GW190521 under a mass-ratio prior uniform in $Q \in [1,4]$ and using the state-of-the-art waveform model for black-hole mergers \texttt{NRSur7dq4}. We find a $90\%$ credible region for the black-hole masses extending far outside what originally reported by \cite{GW190521D}, where our maximum likelihood masses reside. We find a $15\%$ probability that both black holes avoid the pair-instability supernova gap. We infer a three-dimensional sky-location highly consistent with ZTF19abanrhr, obtaining an odds-ratio ${\cal{O}}_{C/R}=72:1$ that strongly favors the hypothesis of a true coincidence over a random one. Combining this event with the neutron-star merger GW170817, we estimate a Hubble constant H$_0=72.1^{+10.6}_{-6.4}\mathrm{km\,s^{-1}\,Mpc^{-1}}$ at the $68\%$ credible level. |
1003.5490 | Sanjeev Dhurandhar | S. Dhurandhar, H. Mukhopadhyay, H. Tagoshi and N. Kanda | Coherent versus coincidence detection of gravitational wave signals from
compact inspiraling binaries | Based on the presentation at the 1st Galileo Xu Guangqi conference,
Shanghai. | Int.J.Mod.Phys.D20:2051-2056,2011 | 10.1142/S0218271811020160 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compare two multi-detector detection strategies, namely, the coincidence
and the coherent, for the detection of spinless inspiraling compact binary
gravitational wave signals. The coincident strategy treats the detectors as if
they are isolated - compares individual detector statistics with their
respective thresholds while the coherent strategy combines the detector network
data {\it phase coherently} to obtain a single detection statistic which is
then compared with a single threshold. In the case of geographically separated
detectors, we also consider an {\it enhanced} coincidence strategy because the
usual (naive) coincidence strategy yields poor results for misaligned
detectors. For simplicity, we consider detector pairs having the same power
spectral density of noise, as that of initial LIGO and also assume the noise to
be stationary and Gaussian. We compare the performances of the methods by
plotting the \emph{receiver operating characteristic} (ROC) for the two
strategies. A single astrophysical source as well as a distribution of sources
is considered. We find that the coherent strategy performs better than the two
coincident strategies under the assumptions of stationary Gaussian detector
noise.
| [
{
"created": "Mon, 29 Mar 2010 10:44:19 GMT",
"version": "v1"
}
] | 2011-09-30 | [
[
"Dhurandhar",
"S.",
""
],
[
"Mukhopadhyay",
"H.",
""
],
[
"Tagoshi",
"H.",
""
],
[
"Kanda",
"N.",
""
]
] | We compare two multi-detector detection strategies, namely, the coincidence and the coherent, for the detection of spinless inspiraling compact binary gravitational wave signals. The coincident strategy treats the detectors as if they are isolated - compares individual detector statistics with their respective thresholds while the coherent strategy combines the detector network data {\it phase coherently} to obtain a single detection statistic which is then compared with a single threshold. In the case of geographically separated detectors, we also consider an {\it enhanced} coincidence strategy because the usual (naive) coincidence strategy yields poor results for misaligned detectors. For simplicity, we consider detector pairs having the same power spectral density of noise, as that of initial LIGO and also assume the noise to be stationary and Gaussian. We compare the performances of the methods by plotting the \emph{receiver operating characteristic} (ROC) for the two strategies. A single astrophysical source as well as a distribution of sources is considered. We find that the coherent strategy performs better than the two coincident strategies under the assumptions of stationary Gaussian detector noise. |
gr-qc/9910042 | Marc Toussaint | Marc Toussaint (University of Cologne) | A numeric solution for metric-affine gravity and Einstein's
gravitational theory with Proca matter | LaTeX2e, 20 pages, 22 figures | Gen.Rel.Grav. 32 (2000) 1689-1709 | 10.1023/A:1001942420350 | Cologne-ThP-He3-oct99 | gr-qc | null | A special case of metric-affine gauge theory of gravity (MAG) is equivalent
to general relativity with Proca matter as source. We study in detail a
corresponding numeric solution of the Reissner-Nordstr"om type. It is static,
spherically symmetric, and of electric type. In particular, this solution has
no horizon, so it has a naked singularity as its origin.
| [
{
"created": "Tue, 12 Oct 1999 15:36:15 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Toussaint",
"Marc",
"",
"University of Cologne"
]
] | A special case of metric-affine gauge theory of gravity (MAG) is equivalent to general relativity with Proca matter as source. We study in detail a corresponding numeric solution of the Reissner-Nordstr"om type. It is static, spherically symmetric, and of electric type. In particular, this solution has no horizon, so it has a naked singularity as its origin. |
1110.2157 | Valentin Bonzom | Valentin Bonzom and Alok Laddha | Lessons from Toy-Models for the Dynamics of Loop Quantum Gravity | null | SIGMA 8 (2012), 009, 50 pages | 10.3842/SIGMA.2012.009 | pi-qg-243 | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/3.0/ | We review some approaches to the Hamiltonian dynamics of (loop) quantum
gravity, the main issues being the regularization of the Hamiltonian and the
continuum limit. First, Thiemann's definition of the quantum Hamiltonian is
presented, and then more recent approaches. They are based on toy models which
provide new insights into the difficulties and ambiguities faced in Thiemann's
construction. The models we use are parametrized field theories, the
topological BF model of which a special case is three-dimensional gravity which
describes quantum flat space, and Regge lattice gravity.
| [
{
"created": "Mon, 10 Oct 2011 19:44:34 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Mar 2012 06:03:39 GMT",
"version": "v2"
}
] | 2012-03-08 | [
[
"Bonzom",
"Valentin",
""
],
[
"Laddha",
"Alok",
""
]
] | We review some approaches to the Hamiltonian dynamics of (loop) quantum gravity, the main issues being the regularization of the Hamiltonian and the continuum limit. First, Thiemann's definition of the quantum Hamiltonian is presented, and then more recent approaches. They are based on toy models which provide new insights into the difficulties and ambiguities faced in Thiemann's construction. The models we use are parametrized field theories, the topological BF model of which a special case is three-dimensional gravity which describes quantum flat space, and Regge lattice gravity. |
gr-qc/0412075 | Mario Goto | Mario Goto | Charge Tempered Cosmological Model | Revised version extended to includ analytical solution of the
modified Friedmann equation and the red shift formula with gravitational
together the recessional velocity dependence. (23 pages) | null | null | null | gr-qc | null | The main purpose of this work is to obtain the metric of a Charge Tempered
Cosmological Model, a slightly modified Standard Cosmological Model by a small
excess of charge density, distributed uniformly in accordance with the
Cosmological Principle, the global Coulomb interaction incorporated in this
metric. The particularity of this model is that the commoving observer
referential where the metric belongs is non inertial, which consequence is that
clocks at different position can not be synchronized. The new metric is
constrained to k goint to 0, with dependence on a charge parameter, and related
to a modified Friedmann equation, but it is constrained to a positive
deceleration parameter and the hyperbolic solution . Nevertheless, there are
corrections to do, valid just for a long range distances. For example, the red
shift has, now, dependences on the gravitational potential together the
recessional motion. In any way, this model accepts as well the cosmological
constant and its physical counterpart, the dark energy.
| [
{
"created": "Wed, 15 Dec 2004 18:45:25 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Oct 2005 13:04:30 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Goto",
"Mario",
""
]
] | The main purpose of this work is to obtain the metric of a Charge Tempered Cosmological Model, a slightly modified Standard Cosmological Model by a small excess of charge density, distributed uniformly in accordance with the Cosmological Principle, the global Coulomb interaction incorporated in this metric. The particularity of this model is that the commoving observer referential where the metric belongs is non inertial, which consequence is that clocks at different position can not be synchronized. The new metric is constrained to k goint to 0, with dependence on a charge parameter, and related to a modified Friedmann equation, but it is constrained to a positive deceleration parameter and the hyperbolic solution . Nevertheless, there are corrections to do, valid just for a long range distances. For example, the red shift has, now, dependences on the gravitational potential together the recessional motion. In any way, this model accepts as well the cosmological constant and its physical counterpart, the dark energy. |
1702.08308 | Tuan Do | Tuan Q. Do and Sonnet Hung Q. Nguyen | Anisotropic power-law inflation in a two-scalar-field model with a mixed
kinetic term | 19 pages, no figures. Accepted for publication in International
Journal of Modern Physics D | International Journal of Modern Physics D 26, 1750072 (2017) | 10.1142/S0218271817500729 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine whether an extended scenario of a two-scalar-field model, in which
a mixed kinetic term of canonical and phantom scalar fields is involved, admits
the Bianchi type I metric, which is homogeneous but anisotropic spacetime, as
its power-law solutions. Then we analyze the stability of the anisotropic
power-law solutions to see whether these solutions respect the cosmic no-hair
conjecture or not during the inflationary phase. In addition, we will also
investigate a special scenario, where the pure kinetic terms of canonical and
phantom fields disappear altogether in field equations, to test again the
validity of cosmic no-hair conjecture. As a result, the cosmic no-hair
conjecture always holds in both these scenarios due to the instability of the
corresponding anisotropic inflationary solutions.
| [
{
"created": "Mon, 27 Feb 2017 14:54:51 GMT",
"version": "v1"
}
] | 2017-02-28 | [
[
"Do",
"Tuan Q.",
""
],
[
"Nguyen",
"Sonnet Hung Q.",
""
]
] | We examine whether an extended scenario of a two-scalar-field model, in which a mixed kinetic term of canonical and phantom scalar fields is involved, admits the Bianchi type I metric, which is homogeneous but anisotropic spacetime, as its power-law solutions. Then we analyze the stability of the anisotropic power-law solutions to see whether these solutions respect the cosmic no-hair conjecture or not during the inflationary phase. In addition, we will also investigate a special scenario, where the pure kinetic terms of canonical and phantom fields disappear altogether in field equations, to test again the validity of cosmic no-hair conjecture. As a result, the cosmic no-hair conjecture always holds in both these scenarios due to the instability of the corresponding anisotropic inflationary solutions. |
1205.6954 | Christian Corda cordac | Christian Corda | Radiation dominated era and the power of general relativity | 7 pages, 1 figure, accepted for publication in Europhysics Letters | EPL, 99, 10001 (2012) | 10.1209/0295-5075/99/10001 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An analysis in the framework of the radiation dominated era permits to put
bounds on the weak modification of general relativity which arises from the
Lagrangian R^{1+epsilon}. Such a theory has been recently discussed in various
papers in the literature. The new bounds together with previous ones in the
literature rule out this theory in an ultimate way.
| [
{
"created": "Thu, 31 May 2012 10:44:32 GMT",
"version": "v1"
}
] | 2012-07-13 | [
[
"Corda",
"Christian",
""
]
] | An analysis in the framework of the radiation dominated era permits to put bounds on the weak modification of general relativity which arises from the Lagrangian R^{1+epsilon}. Such a theory has been recently discussed in various papers in the literature. The new bounds together with previous ones in the literature rule out this theory in an ultimate way. |
gr-qc/0407075 | Pawel O. Mazur | Pawel O. Mazur, Emil Mottola (University of South Carolina, Los Alamos
National Laboratory) | Gravitational Vacuum Condensate Stars | 17 pages, LaTeX file | Proc.Nat.Acad.Sci.101:9545-9550,2004 | 10.1073/pnas.0402717101 | null | gr-qc hep-ph hep-th quant-ph | null | A new final state of gravitational collapse is proposed. By extending the
concept of Bose-Einstein condensation to gravitational systems, a cold, dark,
compact object with an interior de Sitter condensate $p_{_V} = -\rho_{_V}$ and
an exterior Schwarzschild geometry of arbitrary total mass $M$ is constructed.
These are separated by a shell with a small but finite proper thickness $\ell$
of fluid with equation of state $p=+\rho$, replacing both the Schwarzschild and
de Sitter classical horizons. The new solution has no singularities, no event
horizons, and a global time. Its entropy is maximized under small fluctuations
and is given by the standard hydrodynamic entropy of the thin shell, which is
of order $k_{_B}\ell Mc/\hbar$, instead of the Bekenstein-Hawking entropy
formula, $S_{_{BH}}= 4\pi k_{_B} G M^2/\hbar c$. Hence unlike black holes, the
new solution is thermodynamically stable and has no information paradox.
| [
{
"created": "Tue, 20 Jul 2004 00:31:46 GMT",
"version": "v1"
}
] | 2009-10-19 | [
[
"Mazur",
"Pawel O.",
"",
"University of South Carolina, Los Alamos\n National Laboratory"
],
[
"Mottola",
"Emil",
"",
"University of South Carolina, Los Alamos\n National Laboratory"
]
] | A new final state of gravitational collapse is proposed. By extending the concept of Bose-Einstein condensation to gravitational systems, a cold, dark, compact object with an interior de Sitter condensate $p_{_V} = -\rho_{_V}$ and an exterior Schwarzschild geometry of arbitrary total mass $M$ is constructed. These are separated by a shell with a small but finite proper thickness $\ell$ of fluid with equation of state $p=+\rho$, replacing both the Schwarzschild and de Sitter classical horizons. The new solution has no singularities, no event horizons, and a global time. Its entropy is maximized under small fluctuations and is given by the standard hydrodynamic entropy of the thin shell, which is of order $k_{_B}\ell Mc/\hbar$, instead of the Bekenstein-Hawking entropy formula, $S_{_{BH}}= 4\pi k_{_B} G M^2/\hbar c$. Hence unlike black holes, the new solution is thermodynamically stable and has no information paradox. |
0907.4930 | Richard Woodard | S. P. Miao (University of Utrecht) N. C. Tsamis (University of Crete)
R. P. Woodard (University of Florida) | Transforming to Lorentz Gauge on de Sitter | 45 pages | J.Math.Phys.50:122502,2009 | 10.1063/1.3266179 | UFIFT-QG-09-05 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We demonstrate that certain gauge fixing functionals cannot be added to the
action on backgrounds such as de Sitter in which a linearization instability is
present. We also construct the field dependent gauge transformation which
carries the electromagnetic vector potential from a convenient, non-de Sitter
invariant gauge to the de Sitter invariant, Lorentz gauge. The transformed
propagator agrees with the de Sitter invariant result previously found by
solving the propagator equation in Lorentz gauge. This shows that the gauge
transformation technique will eliminate unphysical breaking of de Sitter
invariance introduced by a gauge condition. It is suggested that the same
technique can be used to finally resolve the issue of whether or not free
gravitons are de Sitter invariant.
| [
{
"created": "Tue, 28 Jul 2009 15:11:16 GMT",
"version": "v1"
}
] | 2010-01-15 | [
[
"Miao",
"S. P.",
"",
"University of Utrecht"
],
[
"Tsamis",
"N. C.",
"",
"University of Crete"
],
[
"Woodard",
"R. P.",
"",
"University of Florida"
]
] | We demonstrate that certain gauge fixing functionals cannot be added to the action on backgrounds such as de Sitter in which a linearization instability is present. We also construct the field dependent gauge transformation which carries the electromagnetic vector potential from a convenient, non-de Sitter invariant gauge to the de Sitter invariant, Lorentz gauge. The transformed propagator agrees with the de Sitter invariant result previously found by solving the propagator equation in Lorentz gauge. This shows that the gauge transformation technique will eliminate unphysical breaking of de Sitter invariance introduced by a gauge condition. It is suggested that the same technique can be used to finally resolve the issue of whether or not free gravitons are de Sitter invariant. |
gr-qc/0411099 | Carlos Kozameh | Emanuel Gallo, Mirta Iriondo, and Carlos Kozameh (University of
Cordoba, Argentina) | Cartan's equivalence method and null coframes in General Relativity | 33 pages. To be published in Class. Quantum Grav | Class.Quant.Grav. 22 (2005) 1881-1901 | 10.1088/0264-9381/22/9/025 | null | gr-qc | null | Using Cartan's equivalence method for point transformations we obtain from
first principles the conformal geometry associated with third order ODEs and a
special class of PDEs in two dimensions. We explicitly construct the null
tetrads of a family of Lorentzian metrics, the conformal group in three and
four dimensions and the so called normal metric connection. A special feature
of this connection is that the non vanishing components of its torsion depend
on one relative invariant, the (generalized) W\"unschmann Invariant. We show
that the above mentioned construction naturally contains the Null Surface
Formulation of General Relativity.
| [
{
"created": "Fri, 19 Nov 2004 14:16:52 GMT",
"version": "v1"
},
{
"created": "Mon, 22 Nov 2004 21:14:39 GMT",
"version": "v2"
},
{
"created": "Wed, 6 Apr 2005 17:14:25 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Gallo",
"Emanuel",
"",
"University of\n Cordoba, Argentina"
],
[
"Iriondo",
"Mirta",
"",
"University of\n Cordoba, Argentina"
],
[
"Kozameh",
"Carlos",
"",
"University of\n Cordoba, Argentina"
]
] | Using Cartan's equivalence method for point transformations we obtain from first principles the conformal geometry associated with third order ODEs and a special class of PDEs in two dimensions. We explicitly construct the null tetrads of a family of Lorentzian metrics, the conformal group in three and four dimensions and the so called normal metric connection. A special feature of this connection is that the non vanishing components of its torsion depend on one relative invariant, the (generalized) W\"unschmann Invariant. We show that the above mentioned construction naturally contains the Null Surface Formulation of General Relativity. |
2303.15923 | Michele Maggiore | Marica Branchesi, Michele Maggiore, David Alonso, Charles Badger,
Biswajit Banerjee, Freija Beirnaert, Enis Belgacem, Swetha Bhagwat, Guillaume
Boileau, Ssohrab Borhanian, Daniel David Brown, Man Leong Chan, Giulia Cusin,
Stefan L. Danilishin, Jerome Degallaix, Valerio De Luca, Arnab Dhani, Tim
Dietrich, Ulyana Dupletsa, Stefano Foffa, Gabriele Franciolini, Andreas
Freise, Gianluca Gemme, Boris Goncharov, Archisman Ghosh, Francesca
Gulminelli, Ish Gupta, Pawan Kumar Gupta, Jan Harms, Nandini Hazra, Stefan
Hild, Tanja Hinderer, Ik Siong Heng, Francesco Iacovelli, Justin Janquart,
Kamiel Janssens, Alexander C. Jenkins, Chinmay Kalaghatgi, Xhesika Koroveshi,
Tjonnie G.F. Li, Yufeng Li, Eleonora Loffredo, Elisa Maggio, Michele
Mancarella, Michela Mapelli, Katarina Martinovic, Andrea Maselli, Patrick
Meyers, Andrew L. Miller, Chiranjib Mondal, Niccol\`o Muttoni, Harsh Narola,
Micaela Oertel, Gor Oganesyan, Costantino Pacilio, Cristiano Palomba, Paolo
Pani, Antonio Pasqualetti, Albino Perego, Carole P\`erigois, Mauro Pieroni,
Ornella Juliana Piccinni, Anna Puecher, Paola Puppo, Angelo Ricciardone,
Antonio Riotto, Samuele Ronchini, Mairi Sakellariadou, Anuradha Samajdar,
Filippo Santoliquido, B.S. Sathyaprakash, Jessica Steinlechner, Sebastian
Steinlechner, Andrei Utina, Chris Van Den Broeck, and Teng Zhang | Science with the Einstein Telescope: a comparison of different designs | 197 pages, 73 figures. v2: corrections in the part on the sensitivity
to stochastic backgrounds. Accepted in JCAP | null | 10.1088/1475-7516/2023/07/068 | ET-0084A-23 | gr-qc astro-ph.CO astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Einstein Telescope (ET), the European project for a third-generation
gravitational-wave detector, has a reference configuration based on a
triangular shape consisting of three nested detectors with 10 km arms, where in
each arm there is a `xylophone' configuration made of an interferometer tuned
toward high frequencies, and an interferometer tuned toward low frequencies and
working at cryogenic temperature. Here, we examine the scientific perspectives
under possible variations of this reference design. We perform a detailed
evaluation of the science case for a single triangular geometry observatory,
and we compare it with the results obtained for a network of two L-shaped
detectors (either parallel or misaligned) located in Europe, considering
different choices of arm-length for both the triangle and the 2L geometries. We
also study how the science output changes in the absence of the low-frequency
instrument, both for the triangle and the 2L configurations. We examine a broad
class of simple `metrics' that quantify the science output, related to compact
binary coalescences, multi-messenger astronomy and stochastic backgrounds, and
we then examine the impact of different detector designs on a more specific set
of scientific objectives.
| [
{
"created": "Tue, 28 Mar 2023 12:29:33 GMT",
"version": "v1"
},
{
"created": "Sat, 17 Jun 2023 10:49:26 GMT",
"version": "v2"
}
] | 2023-08-09 | [
[
"Branchesi",
"Marica",
""
],
[
"Maggiore",
"Michele",
""
],
[
"Alonso",
"David",
""
],
[
"Badger",
"Charles",
""
],
[
"Banerjee",
"Biswajit",
""
],
[
"Beirnaert",
"Freija",
""
],
[
"Belgacem",
"Enis",
""
],
[
"Bhagwat",
"Swetha",
""
],
[
"Boileau",
"Guillaume",
""
],
[
"Borhanian",
"Ssohrab",
""
],
[
"Brown",
"Daniel David",
""
],
[
"Chan",
"Man Leong",
""
],
[
"Cusin",
"Giulia",
""
],
[
"Danilishin",
"Stefan L.",
""
],
[
"Degallaix",
"Jerome",
""
],
[
"De Luca",
"Valerio",
""
],
[
"Dhani",
"Arnab",
""
],
[
"Dietrich",
"Tim",
""
],
[
"Dupletsa",
"Ulyana",
""
],
[
"Foffa",
"Stefano",
""
],
[
"Franciolini",
"Gabriele",
""
],
[
"Freise",
"Andreas",
""
],
[
"Gemme",
"Gianluca",
""
],
[
"Goncharov",
"Boris",
""
],
[
"Ghosh",
"Archisman",
""
],
[
"Gulminelli",
"Francesca",
""
],
[
"Gupta",
"Ish",
""
],
[
"Gupta",
"Pawan Kumar",
""
],
[
"Harms",
"Jan",
""
],
[
"Hazra",
"Nandini",
""
],
[
"Hild",
"Stefan",
""
],
[
"Hinderer",
"Tanja",
""
],
[
"Heng",
"Ik Siong",
""
],
[
"Iacovelli",
"Francesco",
""
],
[
"Janquart",
"Justin",
""
],
[
"Janssens",
"Kamiel",
""
],
[
"Jenkins",
"Alexander C.",
""
],
[
"Kalaghatgi",
"Chinmay",
""
],
[
"Koroveshi",
"Xhesika",
""
],
[
"Li",
"Tjonnie G. F.",
""
],
[
"Li",
"Yufeng",
""
],
[
"Loffredo",
"Eleonora",
""
],
[
"Maggio",
"Elisa",
""
],
[
"Mancarella",
"Michele",
""
],
[
"Mapelli",
"Michela",
""
],
[
"Martinovic",
"Katarina",
""
],
[
"Maselli",
"Andrea",
""
],
[
"Meyers",
"Patrick",
""
],
[
"Miller",
"Andrew L.",
""
],
[
"Mondal",
"Chiranjib",
""
],
[
"Muttoni",
"Niccolò",
""
],
[
"Narola",
"Harsh",
""
],
[
"Oertel",
"Micaela",
""
],
[
"Oganesyan",
"Gor",
""
],
[
"Pacilio",
"Costantino",
""
],
[
"Palomba",
"Cristiano",
""
],
[
"Pani",
"Paolo",
""
],
[
"Pasqualetti",
"Antonio",
""
],
[
"Perego",
"Albino",
""
],
[
"Pèrigois",
"Carole",
""
],
[
"Pieroni",
"Mauro",
""
],
[
"Piccinni",
"Ornella Juliana",
""
],
[
"Puecher",
"Anna",
""
],
[
"Puppo",
"Paola",
""
],
[
"Ricciardone",
"Angelo",
""
],
[
"Riotto",
"Antonio",
""
],
[
"Ronchini",
"Samuele",
""
],
[
"Sakellariadou",
"Mairi",
""
],
[
"Samajdar",
"Anuradha",
""
],
[
"Santoliquido",
"Filippo",
""
],
[
"Sathyaprakash",
"B. S.",
""
],
[
"Steinlechner",
"Jessica",
""
],
[
"Steinlechner",
"Sebastian",
""
],
[
"Utina",
"Andrei",
""
],
[
"Broeck",
"Chris Van Den",
""
],
[
"Zhang",
"Teng",
""
]
] | The Einstein Telescope (ET), the European project for a third-generation gravitational-wave detector, has a reference configuration based on a triangular shape consisting of three nested detectors with 10 km arms, where in each arm there is a `xylophone' configuration made of an interferometer tuned toward high frequencies, and an interferometer tuned toward low frequencies and working at cryogenic temperature. Here, we examine the scientific perspectives under possible variations of this reference design. We perform a detailed evaluation of the science case for a single triangular geometry observatory, and we compare it with the results obtained for a network of two L-shaped detectors (either parallel or misaligned) located in Europe, considering different choices of arm-length for both the triangle and the 2L geometries. We also study how the science output changes in the absence of the low-frequency instrument, both for the triangle and the 2L configurations. We examine a broad class of simple `metrics' that quantify the science output, related to compact binary coalescences, multi-messenger astronomy and stochastic backgrounds, and we then examine the impact of different detector designs on a more specific set of scientific objectives. |
0708.0708 | Chul-Moon Yoo | Chul-Moon Yoo, Hideki Ishihara, Masashi Kimura, Ken Matsuno and Shinya
Tomizawa | Horizons of Coalescing Black Holes on Eguchi-Hanson Space | 20 pages, 11 figures CQG accepted version | Class.Quant.Grav.25:095017,2008 | 10.1088/0264-9381/25/9/095017 | OCU-PHYS-272, AP-GR-46,YITP-08-09 | gr-qc hep-th | null | Using the numerical method, we study dynamics of coalescing black holes on
the Eguchi-Hanson base space. Effects of a difference in spacetime topology on
the black hole dynamics is discussed. We analyze appearance and disappearance
process of marginal surfaces. In our calculation, the area of a coverall black
hole horizon at the creation time in the coalescing black holes solutions on
Eguchi-Hanson space is larger than that in the five-dimensional Kastor-Traschen
solutions. This fact suggests that the black hole production on the
Eguchi-Hanson space is easier than that on the flat space.
| [
{
"created": "Mon, 6 Aug 2007 06:37:33 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Apr 2008 07:34:18 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Yoo",
"Chul-Moon",
""
],
[
"Ishihara",
"Hideki",
""
],
[
"Kimura",
"Masashi",
""
],
[
"Matsuno",
"Ken",
""
],
[
"Tomizawa",
"Shinya",
""
]
] | Using the numerical method, we study dynamics of coalescing black holes on the Eguchi-Hanson base space. Effects of a difference in spacetime topology on the black hole dynamics is discussed. We analyze appearance and disappearance process of marginal surfaces. In our calculation, the area of a coverall black hole horizon at the creation time in the coalescing black holes solutions on Eguchi-Hanson space is larger than that in the five-dimensional Kastor-Traschen solutions. This fact suggests that the black hole production on the Eguchi-Hanson space is easier than that on the flat space. |
1602.02456 | Ikjyot Singh Kohli | Ikjyot Singh Kohli | On Past Singularities in $k=0$ FLRW Cosmologies | Updated some of the contents and format | null | null | null | gr-qc astro-ph.CO math-ph math.DS math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The fundamental singularity theorem of FLRW cosmologies assumes that the
matter content in the cosmological model obeys the strong energy condition
along with a nonpositive cosmological constant which gives rise to an
irrotational geodesic singularity. In this paper, we show that the important
case of a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker universe with
barotropic matter obeying only the \emph{weak} energy condition with a
nonnegative cosmological constant also contains a past singularity. We
accomplish this using topological methods from dynamical systems theory. The
methods employed in this paper are sufficiently general that they could be
extended to other models to study the existence of past singularities.
| [
{
"created": "Mon, 8 Feb 2016 03:29:06 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Feb 2016 15:05:36 GMT",
"version": "v2"
},
{
"created": "Fri, 9 Sep 2016 15:17:55 GMT",
"version": "v3"
}
] | 2016-09-12 | [
[
"Kohli",
"Ikjyot Singh",
""
]
] | The fundamental singularity theorem of FLRW cosmologies assumes that the matter content in the cosmological model obeys the strong energy condition along with a nonpositive cosmological constant which gives rise to an irrotational geodesic singularity. In this paper, we show that the important case of a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker universe with barotropic matter obeying only the \emph{weak} energy condition with a nonnegative cosmological constant also contains a past singularity. We accomplish this using topological methods from dynamical systems theory. The methods employed in this paper are sufficiently general that they could be extended to other models to study the existence of past singularities. |
1709.05319 | Sebasti\'an Bahamonde | Sebastian Bahamonde | Generalised nonminimally gravity-matter coupled theory | Matches published version in EPJC | Eur. Phys. J. C (2018) no 78, 326 | 10.1140/epjc/s10052-018-5793-1 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, a new generalised gravity-matter coupled theory of gravity is
presented. This theory is constructed by assuming an action with an arbitrary
function $f(T,B,L_m)$ which depends on the scalar torsion $T$, the boundary
term $B=\nabla_{\mu}T^{\mu}$ and the matter Lagrangian $L_m$. Since the
function depends on $B$ which appears in $R=-T+B$, it is possible to also
reproduce curvature-matter coupled models such as $f(R,L_m)$ gravity.
Additionally, the full theory also contains some interesting new teleparallel
gravity-matter coupled theories of gravities such as $f(T,L_m)$ or $C_1 T+
f(B,L_m)$. The complete dynamical system for flat FLRW cosmology is presented
and for some specific cases of the function, the corresponding cosmological
model is studied. When it is necessary, the connection of our theory and the
dynamical system of other well-known theories is discussed.
| [
{
"created": "Fri, 15 Sep 2017 17:14:29 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Apr 2018 18:16:41 GMT",
"version": "v2"
},
{
"created": "Sun, 22 Apr 2018 12:12:46 GMT",
"version": "v3"
}
] | 2018-04-24 | [
[
"Bahamonde",
"Sebastian",
""
]
] | In this paper, a new generalised gravity-matter coupled theory of gravity is presented. This theory is constructed by assuming an action with an arbitrary function $f(T,B,L_m)$ which depends on the scalar torsion $T$, the boundary term $B=\nabla_{\mu}T^{\mu}$ and the matter Lagrangian $L_m$. Since the function depends on $B$ which appears in $R=-T+B$, it is possible to also reproduce curvature-matter coupled models such as $f(R,L_m)$ gravity. Additionally, the full theory also contains some interesting new teleparallel gravity-matter coupled theories of gravities such as $f(T,L_m)$ or $C_1 T+ f(B,L_m)$. The complete dynamical system for flat FLRW cosmology is presented and for some specific cases of the function, the corresponding cosmological model is studied. When it is necessary, the connection of our theory and the dynamical system of other well-known theories is discussed. |
gr-qc/9804063 | Giovanni Amelino-Camelia | Giovanni Amelino-Camelia | On the area operators of the Husain-Kuchar-Rovelli model and
Canonical/Loop Quantum Gravity | LaTex, 8 pages | Mod.Phys.Lett. A13 (1998) 1155-1161 | 10.1142/S0217732398001224 | NEIP-98-003 | gr-qc | null | I investigate the relation between an operative definition of the area of a
surface specified by matter fields and the area operators recently introduced
in the canonical/loop approach to Quantum Gravity and in Rovelli's variant of
the Husain-Kuchar Quantum-Gravity toy model. The results suggest that the
discreteness of the spectra of the area operators might not be observable.
| [
{
"created": "Fri, 24 Apr 1998 09:41:25 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Amelino-Camelia",
"Giovanni",
""
]
] | I investigate the relation between an operative definition of the area of a surface specified by matter fields and the area operators recently introduced in the canonical/loop approach to Quantum Gravity and in Rovelli's variant of the Husain-Kuchar Quantum-Gravity toy model. The results suggest that the discreteness of the spectra of the area operators might not be observable. |
2206.10336 | Gaurav Gadbail | Gaurav N. Gadbail, Simran Arora, P.K. Sahoo | Generalized Chaplygin gas and accelerating universe in $f(Q,T)$ gravity | Physics of the Dark Universe published version | Physics of the Dark Universe, 37 (2022) 101074 | 10.1016/j.dark.2022.101074 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The generalized Chaplygin gas (GCG), which has an unusual perfect fluid
equation of state, is another promising candidate for dark energy. We
investigate the GCG scenario coupled with a baryonic matter in a newly
suggested $f(Q,T)$ gravity, an arbitrary function of non-metricity $Q$ and the
trace of energy-momentum tensor $T$. We consider the functional form of $f(Q,
T)$ as a linear combination of $Q$ and an arbitrary function of $T$, denoted by
$h(T)$. Furthermore, we obtain two different functional forms of the $f(Q,T)$
model under high pressure and high-density scenarios of GCG. We also test each
model with the recent Pantheon supernovae data set of 1048 data points, Hubble
data set of 31 points, and baryon acoustic oscillations. The deceleration
parameter is constructed using $OHD+SNeIa+BAO$, predicting a transition from
decelerated to accelerated phases of the universe expansion. Also, the equation
of state parameter acquires a negative behavior depicting acceleration.
Finally, we analyze the statefinder diagnostic to discriminate between the GCG
and other dark energy models.
| [
{
"created": "Fri, 17 Jun 2022 06:58:51 GMT",
"version": "v1"
}
] | 2022-06-24 | [
[
"Gadbail",
"Gaurav N.",
""
],
[
"Arora",
"Simran",
""
],
[
"Sahoo",
"P. K.",
""
]
] | The generalized Chaplygin gas (GCG), which has an unusual perfect fluid equation of state, is another promising candidate for dark energy. We investigate the GCG scenario coupled with a baryonic matter in a newly suggested $f(Q,T)$ gravity, an arbitrary function of non-metricity $Q$ and the trace of energy-momentum tensor $T$. We consider the functional form of $f(Q, T)$ as a linear combination of $Q$ and an arbitrary function of $T$, denoted by $h(T)$. Furthermore, we obtain two different functional forms of the $f(Q,T)$ model under high pressure and high-density scenarios of GCG. We also test each model with the recent Pantheon supernovae data set of 1048 data points, Hubble data set of 31 points, and baryon acoustic oscillations. The deceleration parameter is constructed using $OHD+SNeIa+BAO$, predicting a transition from decelerated to accelerated phases of the universe expansion. Also, the equation of state parameter acquires a negative behavior depicting acceleration. Finally, we analyze the statefinder diagnostic to discriminate between the GCG and other dark energy models. |
1307.1787 | Yurii Ignatyev | Yu.G. Ignat'ev | The cosmological evolution of the cosmological plasma with interpartial
scalar interaction. I. The canonic formulation of classical scalar
interaction | 8 pages | Russian Physics Journal, Volume 55, Number 2 (2012), 166-172 | 10.1007/s11182-012-9790-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | On the basis of Hamilton a formalism the dynamic equations of movement scalar
charged particles in a classical scalar field are formulated. Unlike earlier
published works of the author the model with zero own weight of particles is
considered. Linear integrals of movement are found and ambiguity of
communication between kinematic speed and an impulse of particles is specified.
| [
{
"created": "Sat, 6 Jul 2013 14:32:35 GMT",
"version": "v1"
}
] | 2013-07-09 | [
[
"Ignat'ev",
"Yu. G.",
""
]
] | On the basis of Hamilton a formalism the dynamic equations of movement scalar charged particles in a classical scalar field are formulated. Unlike earlier published works of the author the model with zero own weight of particles is considered. Linear integrals of movement are found and ambiguity of communication between kinematic speed and an impulse of particles is specified. |
1707.07098 | Masooma Ali | Masooma Ali and Viqar Husain | Mixmaster dynamics in the dust time gauge | 27 pages, 4 figures | Phys. Rev. D 96, 044032 (2017) | 10.1103/PhysRevD.96.044032 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the Hamiltonian dynamics of the dust-Bianchi IX universe in dust
time gauge. This model has three physical metric degrees of freedom, with
evolution determined by a time-independent physical Hamiltonian. This approach
gives a new physical picture where dust-Bianchi IX dynamics is described by
oscillations between dust-Kasner solutions, rather than between vacuum-Kasner
solutions. We derive a generalized transition law between these phases, which
has a matter component. Sufficiently close to a singularity, we show that this
law reduces to the vacuum Belinski-Khalatnikov-Lifshitz map. We include an
analysis with dust and a scalar field. Lastly, we describe a path integral
quantization using the dust-time physical Hamiltonian and derive an effective
action for the dust-Kasner model by integrating out the anisotropy degrees of
freedom.
| [
{
"created": "Sat, 22 Jul 2017 03:33:45 GMT",
"version": "v1"
}
] | 2017-08-30 | [
[
"Ali",
"Masooma",
""
],
[
"Husain",
"Viqar",
""
]
] | We study the Hamiltonian dynamics of the dust-Bianchi IX universe in dust time gauge. This model has three physical metric degrees of freedom, with evolution determined by a time-independent physical Hamiltonian. This approach gives a new physical picture where dust-Bianchi IX dynamics is described by oscillations between dust-Kasner solutions, rather than between vacuum-Kasner solutions. We derive a generalized transition law between these phases, which has a matter component. Sufficiently close to a singularity, we show that this law reduces to the vacuum Belinski-Khalatnikov-Lifshitz map. We include an analysis with dust and a scalar field. Lastly, we describe a path integral quantization using the dust-time physical Hamiltonian and derive an effective action for the dust-Kasner model by integrating out the anisotropy degrees of freedom. |
gr-qc/0501016 | Gaurav Khanna | Daniel Cartin, Gaurav Khanna | Absence of pre-classical solutions in Bianchi I loop quantum cosmology | 4 pages, no figures, version to appear in PRL | Phys.Rev.Lett. 94 (2005) 111302 | 10.1103/PhysRevLett.94.111302 | null | gr-qc hep-th | null | Loop quantum cosmology, the symmetry reduction of quantum geometry for the
study of various cosmological situations, leads to a difference equation for
its quantum evolution equation. To ensure that solutions of this equation act
in the expected classical manner far from singularities, additional
restrictions are imposed on the solution. In this paper, we consider the
Bianchi I model, both the vacuum case and the addition of a cosmological
constant, and show using generating function techniques that only the zero
solution satisfies these constraints. This implies either that there are
technical difficulties with the current method of quantizing the evolution
equation, or else loop quantum gravity imposes strong restrictions on the
physically allowed solutions.
| [
{
"created": "Thu, 6 Jan 2005 15:14:38 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Feb 2005 00:48:17 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Cartin",
"Daniel",
""
],
[
"Khanna",
"Gaurav",
""
]
] | Loop quantum cosmology, the symmetry reduction of quantum geometry for the study of various cosmological situations, leads to a difference equation for its quantum evolution equation. To ensure that solutions of this equation act in the expected classical manner far from singularities, additional restrictions are imposed on the solution. In this paper, we consider the Bianchi I model, both the vacuum case and the addition of a cosmological constant, and show using generating function techniques that only the zero solution satisfies these constraints. This implies either that there are technical difficulties with the current method of quantizing the evolution equation, or else loop quantum gravity imposes strong restrictions on the physically allowed solutions. |
1808.07352 | Sajad Aghapour | Sajad Aghapour, Ghadir Jafari, Mehdi Golshani | On variational principle and canonical structure of gravitational theory
in double-foliation formalism | 23 pages, Mathematica file included | null | 10.1088/1361-6382/aaef9e | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we analyze the variation of the gravitational action on a
bounded region of spacetime whose boundary contains segments with various
characters, including null. We develop a systematic approach to decompose the
derivative of metric variations into orthogonal and tangential components with
respect to the boundary and express them in terms of variations of geometric
objects associated with the boundary hypersurface. We suggest that a
double-foliation of spacetime provides a natural and useful set-up for treating
the general problem and clarifies the assumptions and results in specialized
ones. In this set-up, we are able to obtain the boundary action necessary for
the variational principle to become well-posed, beside the canonical structure
of the theory, while keeping the variations quite general. Especially, we show
how one can remove the restrictions imposed on the metric variations in
previous works due to the assumption that the boundary character is kept
unaltered. As a result, we find that on null boundaries a new canonical pair
which is related to the change in character of the boundary. This set-up and
the calculation procedure are stated in a way that can be applied to other more
generalized theories of gravity.
| [
{
"created": "Wed, 22 Aug 2018 13:47:45 GMT",
"version": "v1"
},
{
"created": "Sat, 1 Sep 2018 12:25:36 GMT",
"version": "v2"
}
] | 2018-12-26 | [
[
"Aghapour",
"Sajad",
""
],
[
"Jafari",
"Ghadir",
""
],
[
"Golshani",
"Mehdi",
""
]
] | In this paper, we analyze the variation of the gravitational action on a bounded region of spacetime whose boundary contains segments with various characters, including null. We develop a systematic approach to decompose the derivative of metric variations into orthogonal and tangential components with respect to the boundary and express them in terms of variations of geometric objects associated with the boundary hypersurface. We suggest that a double-foliation of spacetime provides a natural and useful set-up for treating the general problem and clarifies the assumptions and results in specialized ones. In this set-up, we are able to obtain the boundary action necessary for the variational principle to become well-posed, beside the canonical structure of the theory, while keeping the variations quite general. Especially, we show how one can remove the restrictions imposed on the metric variations in previous works due to the assumption that the boundary character is kept unaltered. As a result, we find that on null boundaries a new canonical pair which is related to the change in character of the boundary. This set-up and the calculation procedure are stated in a way that can be applied to other more generalized theories of gravity. |
gr-qc/9309016 | Wai Suen | Peter Anninos, David Hobill, Edward Seidel, Larry Smarr and Wai-Mo
Suen | The Collision of Two Black Holes | 14 pages, 93-6 | Phys.Rev.Lett. 71 (1993) 2851-2854 | 10.1103/PhysRevLett.71.2851 | null | gr-qc | null | We study the head-on collision of two equal mass, nonrotating black holes. We
consider a range of cases from holes surrounded by a common horizon to holes
initially separated by about $20M$, where $M$ is the mass of each hole. We
determine the waveforms and energies radiated for both the $\ell = 2$ and
$\ell=4$ waves resulting from the collision. In all cases studied the normal
modes of the final black hole dominate the spectrum. We also estimate
analytically the total gravitational radiation emitted, taking into account the
tidal heating of horizons using the membrane paradigm, and other effects. For
the first time we are able to compare analytic calculations, black hole
perturbation theory, and strong field, nonlinear numerical calculations for
this problem, and we find excellent agreement.
| [
{
"created": "Tue, 14 Sep 1993 23:45:41 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Anninos",
"Peter",
""
],
[
"Hobill",
"David",
""
],
[
"Seidel",
"Edward",
""
],
[
"Smarr",
"Larry",
""
],
[
"Suen",
"Wai-Mo",
""
]
] | We study the head-on collision of two equal mass, nonrotating black holes. We consider a range of cases from holes surrounded by a common horizon to holes initially separated by about $20M$, where $M$ is the mass of each hole. We determine the waveforms and energies radiated for both the $\ell = 2$ and $\ell=4$ waves resulting from the collision. In all cases studied the normal modes of the final black hole dominate the spectrum. We also estimate analytically the total gravitational radiation emitted, taking into account the tidal heating of horizons using the membrane paradigm, and other effects. For the first time we are able to compare analytic calculations, black hole perturbation theory, and strong field, nonlinear numerical calculations for this problem, and we find excellent agreement. |
2302.13599 | Alexey Golovnev | Alexey Golovnev | The geometrical meaning of the Weitzenb\"ock connection | 8 pages; minor additions | International Journal of Geometric Methods in Modern Physics 20
(2023) 2350219 | 10.1142/S0219887823502195 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the current literature, there are many discussions about the local Lorentz
invariance of modified teleparallel gravity. This symmetry is obviously
violated in the classical "pure tetrad" formulation of the theory, while it
gets restored in the "fully covariant" approach. My claim is that, despite many
heated discussions, the two formulations are just equivalent. And the purpose
of this note is to argue that the local Lorentz invariance is not natural for
the modified teleparallel theories at all, making the pure tetrad approach more
fundamentally justified.
| [
{
"created": "Mon, 27 Feb 2023 09:08:12 GMT",
"version": "v1"
},
{
"created": "Sun, 21 May 2023 12:40:36 GMT",
"version": "v2"
}
] | 2024-02-26 | [
[
"Golovnev",
"Alexey",
""
]
] | In the current literature, there are many discussions about the local Lorentz invariance of modified teleparallel gravity. This symmetry is obviously violated in the classical "pure tetrad" formulation of the theory, while it gets restored in the "fully covariant" approach. My claim is that, despite many heated discussions, the two formulations are just equivalent. And the purpose of this note is to argue that the local Lorentz invariance is not natural for the modified teleparallel theories at all, making the pure tetrad approach more fundamentally justified. |
gr-qc/9904074 | Marcelo J. Reboucas | H.L. Carrion, M.J. Reboucas, A.F.F. Teixeira | G\"odel-type Spacetimes in Induced Matter Gravity Theory | 19 pages, Latex, no figures. To Appear in J.Math.Phys.(1999) | J.Math.Phys. 40 (1999) 4011-4027 | 10.1063/1.532939 | CBPF-NF-016/96 | gr-qc astro-ph | null | A five-dimensional (5D) generalized G\"odel-type manifolds are examined in
the light of the equivalence problem techniques, as formulated by Cartan. The
necessary and sufficient conditions for local homogeneity of these 5D manifolds
are derived. The local equivalence of these homogeneous Riemannian manifolds is
studied. It is found that they are characterized by three essential parameters
$k$, $m^2$ and $\omega$: identical triads $(k, m^2, \omega)$ correspond to
locally equivalent 5D manifolds. An irreducible set of isometrically
nonequivalent 5D locally homogeneous Riemannian generalized G\"odel-type
metrics are exhibited. A classification of these manifolds based on the
essential parameters is presented, and the Killing vector fields as well as the
corresponding Lie algebra of each class are determined. It is shown that the
generalized G\"odel-type 5D manifolds admit maximal group of isometry $G_r$
with $r=7$, $r=9$ or $r=15$ depending on the essential parameters $k$, $m^2$
and $\omega$. The breakdown of causality in all these classes of homogeneous
G\"odel-type manifolds are also examined. It is found that in three out of the
six irreducible classes the causality can be violated. The unique generalized
G\"odel-type solution of the induced matter (IM) field equations is found. The
question as to whether the induced matter version of general relativity is an
effective therapy for these type of causal anomalies of general relativity is
also discussed in connection with a recent article by Romero, Tavakol and
Zalaletdinov.
| [
{
"created": "Thu, 29 Apr 1999 01:37:55 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Carrion",
"H. L.",
""
],
[
"Reboucas",
"M. J.",
""
],
[
"Teixeira",
"A. F. F.",
""
]
] | A five-dimensional (5D) generalized G\"odel-type manifolds are examined in the light of the equivalence problem techniques, as formulated by Cartan. The necessary and sufficient conditions for local homogeneity of these 5D manifolds are derived. The local equivalence of these homogeneous Riemannian manifolds is studied. It is found that they are characterized by three essential parameters $k$, $m^2$ and $\omega$: identical triads $(k, m^2, \omega)$ correspond to locally equivalent 5D manifolds. An irreducible set of isometrically nonequivalent 5D locally homogeneous Riemannian generalized G\"odel-type metrics are exhibited. A classification of these manifolds based on the essential parameters is presented, and the Killing vector fields as well as the corresponding Lie algebra of each class are determined. It is shown that the generalized G\"odel-type 5D manifolds admit maximal group of isometry $G_r$ with $r=7$, $r=9$ or $r=15$ depending on the essential parameters $k$, $m^2$ and $\omega$. The breakdown of causality in all these classes of homogeneous G\"odel-type manifolds are also examined. It is found that in three out of the six irreducible classes the causality can be violated. The unique generalized G\"odel-type solution of the induced matter (IM) field equations is found. The question as to whether the induced matter version of general relativity is an effective therapy for these type of causal anomalies of general relativity is also discussed in connection with a recent article by Romero, Tavakol and Zalaletdinov. |
1710.00682 | Waleed El Hanafy | A. Awad, W. El Hanafy, G.G.L. Nashed, S.D. Odintsov, V.K. Oikonomou | Constant-roll Inflation in $f(T)$ Teleparallel Gravity | 29 pages, published in JCAP | JCAP 1807 (2018) no. 07, 026 | 10.1088/1475-7516/2018/07/026 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate in detail the implications of the constant-roll condition on
the inflationary era of a scalar field coupled to a teleparallel $f(T)$
gravity. The resulting cosmological equations constitute a reconstruction
technique which enables us to find either the $f(T)$ gravity which corresponds
to a given cosmological evolution, or the Hubble rate of the cosmological
evolution generated by a fixed $f(T)$ gravity. We also analyze in some detail
the phase space of the constant-roll teleparallel gravity and we discuss the
physical significance of the resulting fixed points and trajectories. Also we
calculate the observational indices of a theory with given $f(T)$ gravity, and
we discuss all the implications of the constant-roll condition on these. As we
demonstrate, the resulting theory can be compatible with the current
observational data, for a wide range of values of the free parameters of the
theory.
| [
{
"created": "Thu, 28 Sep 2017 09:16:24 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Jul 2018 17:18:38 GMT",
"version": "v2"
},
{
"created": "Fri, 13 Jul 2018 18:37:08 GMT",
"version": "v3"
}
] | 2018-07-17 | [
[
"Awad",
"A.",
""
],
[
"Hanafy",
"W. El",
""
],
[
"Nashed",
"G. G. L.",
""
],
[
"Odintsov",
"S. D.",
""
],
[
"Oikonomou",
"V. K.",
""
]
] | We investigate in detail the implications of the constant-roll condition on the inflationary era of a scalar field coupled to a teleparallel $f(T)$ gravity. The resulting cosmological equations constitute a reconstruction technique which enables us to find either the $f(T)$ gravity which corresponds to a given cosmological evolution, or the Hubble rate of the cosmological evolution generated by a fixed $f(T)$ gravity. We also analyze in some detail the phase space of the constant-roll teleparallel gravity and we discuss the physical significance of the resulting fixed points and trajectories. Also we calculate the observational indices of a theory with given $f(T)$ gravity, and we discuss all the implications of the constant-roll condition on these. As we demonstrate, the resulting theory can be compatible with the current observational data, for a wide range of values of the free parameters of the theory. |
1504.01443 | Takahisa Igata | Takahisa Igata, Shinya Tomizawa | Gravitational solitons in Levi-Civita spacetime | 14 pages | null | null | RUP-15-8 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Applying the Pomeransky inverse scattering method to the four-dimensional
vacuum Einstein equation and using the Levi-Civita solution for a seed, we
construct a cylindrically symmetric single-soliton solution. Although the
Levi-Civita spacetime generally includes singularities on its axis of symmetry,
it is shown that for the obtained single-soliton solution, such singularities
can be removed by choice of certain special parameters. This single-soliton
solution describes propagation of nonlinear cylindrical gravitational shock
wave pulses rather than solitonic waves. By analyzing wave amplitudes and
time-dependence of polarization angles, we provides physical description of the
single-soliton solution.
| [
{
"created": "Tue, 7 Apr 2015 00:36:14 GMT",
"version": "v1"
}
] | 2015-04-08 | [
[
"Igata",
"Takahisa",
""
],
[
"Tomizawa",
"Shinya",
""
]
] | Applying the Pomeransky inverse scattering method to the four-dimensional vacuum Einstein equation and using the Levi-Civita solution for a seed, we construct a cylindrically symmetric single-soliton solution. Although the Levi-Civita spacetime generally includes singularities on its axis of symmetry, it is shown that for the obtained single-soliton solution, such singularities can be removed by choice of certain special parameters. This single-soliton solution describes propagation of nonlinear cylindrical gravitational shock wave pulses rather than solitonic waves. By analyzing wave amplitudes and time-dependence of polarization angles, we provides physical description of the single-soliton solution. |
gr-qc/9709043 | G. Kunstatter | G. Kunstatter, R. Petryk and S. Shelemy (U. of Winnipeg) | Hamiltonian Thermodynamics of Black Holes in Generic 2-D Dilaton Gravity | 25 pages Revtex including 7 (eps) figures | Phys.Rev.D57:3537-3547,1998 | 10.1103/PhysRevD.57.3537 | null | gr-qc hep-th | null | We consider the Hamiltonian mechanics and thermodynamics of an eternal black
hole in a box of fixed radius and temperature in generic 2-D dilaton gravity.
Imposing boundary conditions analoguous to those used by Louko and Whiting for
spherically symmetric gravity, we find that the reduced Hamiltonian generically
takes the form: $$ H(M,\phi_+) = \sigma_0 E(M,\phi_+) -{N_0\over 2\pi} S(M) $$
where $E(M,\phi_+)$ is the quasilocal energy of a black hole of mass $M$ inside
a static box (surface of fixed dilaton field $\phi_+$) and $S(M)$ is the
associated classical thermodynamical entropy. $\sigma_0$ and $N_0$ determine
time evolution along the world line of the box and boosts at the bifurcation
point, respectively. An ansatz for the quantum partition function is obtained
by fixing $\sigma_0$ and $N_0$ and then tracing the operator $e^{-\beta H}$
over mass eigenstates. We analyze this partition function in some detail both
generically and for the class of dilaton gravity theories that is obtained by
dimensional reduction of Einstein gravity in n+2 dimensions with $S^n$
spherical symmetry.
| [
{
"created": "Tue, 16 Sep 1997 21:01:17 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Kunstatter",
"G.",
"",
"U. of Winnipeg"
],
[
"Petryk",
"R.",
"",
"U. of Winnipeg"
],
[
"Shelemy",
"S.",
"",
"U. of Winnipeg"
]
] | We consider the Hamiltonian mechanics and thermodynamics of an eternal black hole in a box of fixed radius and temperature in generic 2-D dilaton gravity. Imposing boundary conditions analoguous to those used by Louko and Whiting for spherically symmetric gravity, we find that the reduced Hamiltonian generically takes the form: $$ H(M,\phi_+) = \sigma_0 E(M,\phi_+) -{N_0\over 2\pi} S(M) $$ where $E(M,\phi_+)$ is the quasilocal energy of a black hole of mass $M$ inside a static box (surface of fixed dilaton field $\phi_+$) and $S(M)$ is the associated classical thermodynamical entropy. $\sigma_0$ and $N_0$ determine time evolution along the world line of the box and boosts at the bifurcation point, respectively. An ansatz for the quantum partition function is obtained by fixing $\sigma_0$ and $N_0$ and then tracing the operator $e^{-\beta H}$ over mass eigenstates. We analyze this partition function in some detail both generically and for the class of dilaton gravity theories that is obtained by dimensional reduction of Einstein gravity in n+2 dimensions with $S^n$ spherical symmetry. |
1507.02877 | Milovan Vasilic | Milovan Vasili\'c | Pseudo-Riemannian Universe from Euclidean bulk | 21 pages, 2 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I develop the idea that our world is a brane-like object embedded in
Euclidean bulk. In its ground state, the brane constituent matter is assumed to
be homogeneous and isotropic, and of negligible influence on the bulk geometry.
The analysis of this paper is model independent, in the sense that action
functional of bulk fields is not specified. Instead, the behavior of the brane
is derived from the universally valid conservation equation of the bulk stress
tensor. The present work studies the behavior of a $3$-sphere in the
$5$-dimensional Euclidean bulk. The sphere is made of bulk matter characterized
by the equation of state $p=\alpha\rho$. It is shown that stability of brane
vibrations requires $\alpha < 0$. Then, the stable brane perturbations obey
Klein-Gordon-like equation with an effective metric of Minkowski signature. The
argument is given that it is this effective metric that is detected in physical
measurements. The corresponding effective Universe is analyzed for all the
values of $\alpha<0$. In particular, the effective metric is shown to be a
solution of Einstein's equations coupled to an effective perfect fluid. The
effective energy density and pressure at the present epoch are calculated. So
are the age of the Universe, and the effective cosmological constant. All the
results are presented in two tables. As an illustration, one simple choice of
the brane constituent matter is studied in detail.
| [
{
"created": "Fri, 10 Jul 2015 12:52:20 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Sep 2015 13:29:44 GMT",
"version": "v2"
},
{
"created": "Mon, 12 Oct 2015 12:52:26 GMT",
"version": "v3"
},
{
"created": "Sat, 22 Apr 2017 20:46:06 GMT",
"version": "v4"
}
] | 2017-04-25 | [
[
"Vasilić",
"Milovan",
""
]
] | I develop the idea that our world is a brane-like object embedded in Euclidean bulk. In its ground state, the brane constituent matter is assumed to be homogeneous and isotropic, and of negligible influence on the bulk geometry. The analysis of this paper is model independent, in the sense that action functional of bulk fields is not specified. Instead, the behavior of the brane is derived from the universally valid conservation equation of the bulk stress tensor. The present work studies the behavior of a $3$-sphere in the $5$-dimensional Euclidean bulk. The sphere is made of bulk matter characterized by the equation of state $p=\alpha\rho$. It is shown that stability of brane vibrations requires $\alpha < 0$. Then, the stable brane perturbations obey Klein-Gordon-like equation with an effective metric of Minkowski signature. The argument is given that it is this effective metric that is detected in physical measurements. The corresponding effective Universe is analyzed for all the values of $\alpha<0$. In particular, the effective metric is shown to be a solution of Einstein's equations coupled to an effective perfect fluid. The effective energy density and pressure at the present epoch are calculated. So are the age of the Universe, and the effective cosmological constant. All the results are presented in two tables. As an illustration, one simple choice of the brane constituent matter is studied in detail. |
2404.02646 | Qing-Hua Zhu | Qing-Hua Zhu | Ultralight scalar dark matter versus non-adiabatic perfect fluid dark
matter in pulsar timing | 20 pages, 10 figures | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent evidence of direct detection of stochastic gravitational waves
reported by pulsar timing array collaborations might open a new window for
studying cosmology and astrophysical phenomena. In addition to signals from
gravitational waves, there is motivation to explore residual signals from
oscillating dark matter, which might partially comprise the galactic halo. We
investigate fluctuations in pulsar timing originating from the coherent
oscillation of scalar dark matter up to the subleading order of
$\mathcal{O}(k/m)$, as well as from acoustic oscillations of non-adiabatic
perfect fluid dark matter. Both types of dark matter can generate oscillating
Newtonian potential perturbations and curvature perturbations, thereby
affecting pulsar timing. Our results show distinctive signatures in pulsar
timing residuals and angular correlations for these dark matters. Specifically,
pulsar timing residuals from non-adiabatic perfect fluid dark matter exhibit
different directional dependence and are shown to be more sensitive to the
distance to a pulsar. We also study the angular correlation patterns from these
dark matters in the NANOGrav 15-year data set. The best fit might suggest that
the composition of non-adiabatic perfect fluid dark matter in our galaxy is
much greater than that of ultralight scalar dark matter.
| [
{
"created": "Wed, 3 Apr 2024 11:16:26 GMT",
"version": "v1"
}
] | 2024-04-04 | [
[
"Zhu",
"Qing-Hua",
""
]
] | Recent evidence of direct detection of stochastic gravitational waves reported by pulsar timing array collaborations might open a new window for studying cosmology and astrophysical phenomena. In addition to signals from gravitational waves, there is motivation to explore residual signals from oscillating dark matter, which might partially comprise the galactic halo. We investigate fluctuations in pulsar timing originating from the coherent oscillation of scalar dark matter up to the subleading order of $\mathcal{O}(k/m)$, as well as from acoustic oscillations of non-adiabatic perfect fluid dark matter. Both types of dark matter can generate oscillating Newtonian potential perturbations and curvature perturbations, thereby affecting pulsar timing. Our results show distinctive signatures in pulsar timing residuals and angular correlations for these dark matters. Specifically, pulsar timing residuals from non-adiabatic perfect fluid dark matter exhibit different directional dependence and are shown to be more sensitive to the distance to a pulsar. We also study the angular correlation patterns from these dark matters in the NANOGrav 15-year data set. The best fit might suggest that the composition of non-adiabatic perfect fluid dark matter in our galaxy is much greater than that of ultralight scalar dark matter. |
1011.1473 | Vladan Pankovic | Vladan Pankovic, Darko Kapor | A simplified quantum theoretical derivation of the Unruh and Hawking
temperature | 5 pages, no figures | null | null | PH-D/18-2015 | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we suggest a sufficiently simple for understanding "without
knowing the details of the quantum gravity" and quite correct deduction of the
Unruh temperature (but not whole Unruh radiation process!). Firstly, we shall
directly apply usual consequences of the Unruh radiation and temperature at
surface gravity of a large spherical physical system and we shall show that
corresponding thermal energy can be formally quite correctly presented as the
potential energy absolute value of the classical gravitational interaction
between this large and a small quantum system with well defined
characteristics. Secondly, we shall inversely "postulate" small quantum system
with necessary well defined characteristics and then, after "supposition" on
the equivalence between potential energy absolute value of its gravitational
interaction with large system with thermal energy, we shall obtain exact value
of the Unruh temperature. Moreover, by very simple and correct application of
suggested formalism (with small quantum system) at thermodynamic laws, we shall
successfully study other thermodynamic characteristics, especially entropy,
characteristic for Unruh and Hawking radiation
| [
{
"created": "Thu, 4 Nov 2010 15:54:32 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Dec 2012 09:41:13 GMT",
"version": "v2"
},
{
"created": "Thu, 25 Apr 2013 12:01:05 GMT",
"version": "v3"
},
{
"created": "Thu, 5 Mar 2015 13:49:56 GMT",
"version": "v4"
}
] | 2015-03-06 | [
[
"Pankovic",
"Vladan",
""
],
[
"Kapor",
"Darko",
""
]
] | In this work we suggest a sufficiently simple for understanding "without knowing the details of the quantum gravity" and quite correct deduction of the Unruh temperature (but not whole Unruh radiation process!). Firstly, we shall directly apply usual consequences of the Unruh radiation and temperature at surface gravity of a large spherical physical system and we shall show that corresponding thermal energy can be formally quite correctly presented as the potential energy absolute value of the classical gravitational interaction between this large and a small quantum system with well defined characteristics. Secondly, we shall inversely "postulate" small quantum system with necessary well defined characteristics and then, after "supposition" on the equivalence between potential energy absolute value of its gravitational interaction with large system with thermal energy, we shall obtain exact value of the Unruh temperature. Moreover, by very simple and correct application of suggested formalism (with small quantum system) at thermodynamic laws, we shall successfully study other thermodynamic characteristics, especially entropy, characteristic for Unruh and Hawking radiation |
gr-qc/0012025 | Jacob D. Bekenstein | Jacob D. Bekenstein and Asaf Oron | Extended Kelvin theorem in relativistic magnetohydrodynamics | Invited talk at IARD 2000, the Second International Conference on
Relativistic Dynamics, Bar-Ilan University, Israel, 26-28 June, 2000. To
appear in the proceedings in a special issue of Foundations of Physics | Found.Phys. 31 (2001) 895-907 | 10.1023/A:1017507917267 | null | gr-qc astro-ph physics.flu-dyn | null | We prove the existence of a generalization of Kelvin's circulation theorem in
general relativity which is applicable to perfect isentropic
magnetohydrodynamic flow. The argument is based on a new version of the
Lagrangian for perfect magnetohydrodynamics. We illustrate the new conserved
circulation with the example of a relativistic magnetohydrodynamic flow
possessing three symmetries.
| [
{
"created": "Wed, 6 Dec 2000 13:48:27 GMT",
"version": "v1"
}
] | 2022-10-12 | [
[
"Bekenstein",
"Jacob D.",
""
],
[
"Oron",
"Asaf",
""
]
] | We prove the existence of a generalization of Kelvin's circulation theorem in general relativity which is applicable to perfect isentropic magnetohydrodynamic flow. The argument is based on a new version of the Lagrangian for perfect magnetohydrodynamics. We illustrate the new conserved circulation with the example of a relativistic magnetohydrodynamic flow possessing three symmetries. |
2407.04304 | Spencer Collaviti | Spencer Collaviti, Ling Sun, Marios Galanis, Masha Baryakhtar | Observational prospects of self-interacting scalar superradiance with
next-generation gravitational-wave detectors | null | null | null | null | gr-qc astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Current- and next-generation gravitational-wave observatories may reveal new,
ultralight bosons. Through the superradiance process, these theoretical
particle candidates can form clouds around astrophysical black holes and result
in detectable gravitational-wave radiation. In the absence of detections,
constraints$-$contingent on astrophysical assumptions$-$have been derived using
LIGO-Virgo-KAGRA data on boson masses. However, the searches for ultralight
scalars to date have not adequately considered self-interactions between
particles. Self-interactions that significantly alter superradiance dynamics
are generically present for many scalar models, including axion-like dark
matter candidates and string axions. We implement the most complete treatment
of particle self-interactions available to determine the gravitational-wave
signatures expected from superradiant scalar clouds and revisit the constraints
obtained in a past gravitational-wave search targeting the black hole in Cygnus
X-1. We also project the reach of next-generation gravitational-wave
observatories to scalar particle parameter space in the mass-coupling plane. We
find that while proposed observatories have insufficient reach to
self-interactions that can halt black hole spin-down, next-generation
observatories are essential for expanding the search beyond gravitational
parameter space and can reach a mass and interaction scale of $\sim
10^{-13}-10^{-12}$ eV/c$^2$ and $\gtrsim 10^{17}$ GeV, respectively.
| [
{
"created": "Fri, 5 Jul 2024 07:16:15 GMT",
"version": "v1"
}
] | 2024-07-08 | [
[
"Collaviti",
"Spencer",
""
],
[
"Sun",
"Ling",
""
],
[
"Galanis",
"Marios",
""
],
[
"Baryakhtar",
"Masha",
""
]
] | Current- and next-generation gravitational-wave observatories may reveal new, ultralight bosons. Through the superradiance process, these theoretical particle candidates can form clouds around astrophysical black holes and result in detectable gravitational-wave radiation. In the absence of detections, constraints$-$contingent on astrophysical assumptions$-$have been derived using LIGO-Virgo-KAGRA data on boson masses. However, the searches for ultralight scalars to date have not adequately considered self-interactions between particles. Self-interactions that significantly alter superradiance dynamics are generically present for many scalar models, including axion-like dark matter candidates and string axions. We implement the most complete treatment of particle self-interactions available to determine the gravitational-wave signatures expected from superradiant scalar clouds and revisit the constraints obtained in a past gravitational-wave search targeting the black hole in Cygnus X-1. We also project the reach of next-generation gravitational-wave observatories to scalar particle parameter space in the mass-coupling plane. We find that while proposed observatories have insufficient reach to self-interactions that can halt black hole spin-down, next-generation observatories are essential for expanding the search beyond gravitational parameter space and can reach a mass and interaction scale of $\sim 10^{-13}-10^{-12}$ eV/c$^2$ and $\gtrsim 10^{17}$ GeV, respectively. |
gr-qc/9707053 | Thomas Kloesch | T. Kloesch and T. Strobl | A Global View of Kinks in 1+1 Gravity | 20 pages, 12 figures, uses amssymb | Phys.Rev. D57 (1998) 1034-1044 | 10.1103/PhysRevD.57.1034 | TUW-97-13, PITHA-96/24 | gr-qc hep-th | null | Following Finkelstein and Misner, kinks are non-trivial field configurations
of a field theory, and different kink-numbers correspond to different
disconnected components of the space of allowed field configurations for a
given topology of the base manifold. In a theory of gravity, non-vanishing
kink-numbers are associated to a twisted causal structure. In two dimensions
this means, more specifically, that the light-cone tilts around (non-trivially)
when going along a non-contractible non-selfintersecting loop on spacetime. One
purpose of this paper is to construct the maximal extensions of kink spacetimes
using Penrose diagrams. This will yield surprising insights into their geometry
but also allow us to give generalizations of some well-known examples like the
bare kink and the Misner torus. However, even for an arbitrary 2D metric with a
Killing field we can construct continuous one-parameter families of
inequivalent kinks. This result has already interesting implications in the
flat or deSitter case, but it applies e.g. also to generalized dilaton gravity
solutions. Finally, several coordinate systems for these newly obtained kinks
are discussed.
| [
{
"created": "Fri, 25 Jul 1997 11:27:36 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Kloesch",
"T.",
""
],
[
"Strobl",
"T.",
""
]
] | Following Finkelstein and Misner, kinks are non-trivial field configurations of a field theory, and different kink-numbers correspond to different disconnected components of the space of allowed field configurations for a given topology of the base manifold. In a theory of gravity, non-vanishing kink-numbers are associated to a twisted causal structure. In two dimensions this means, more specifically, that the light-cone tilts around (non-trivially) when going along a non-contractible non-selfintersecting loop on spacetime. One purpose of this paper is to construct the maximal extensions of kink spacetimes using Penrose diagrams. This will yield surprising insights into their geometry but also allow us to give generalizations of some well-known examples like the bare kink and the Misner torus. However, even for an arbitrary 2D metric with a Killing field we can construct continuous one-parameter families of inequivalent kinks. This result has already interesting implications in the flat or deSitter case, but it applies e.g. also to generalized dilaton gravity solutions. Finally, several coordinate systems for these newly obtained kinks are discussed. |
2308.06613 | Ke Yang | Ke Yang, Yue-Zhe Chen, Zheng-Qiao Duan, Ju-Ying Zhao | Static and spherically symmetric black holes in gravity with a
background Kalb-Ramond field | 11 pages and 1 figure, Published version | Phys. Rev. D 108, 124004 (2023) | 10.1103/PhysRevD.108.124004 | null | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | The Lorentz symmetry of gravity is spontaneously broken when the nonminimally
coupled Kalb-Ramond field acquires a nonzero vacuum expectation value. In this
work, we present exact solutions for static and spherically symmetric black
holes in the framework of this Lorentz-violating gravity theory. In order to
explore the physical implications of Lorentz violation, we analyze the
thermodynamic properties of the obtained solutions and evaluate the impact of
Lorentz violation on some classical gravitational experiments within the Solar
System. Furthermore, the Lorentz-violating parameter is constrained by using
the measured results of these experiments.
| [
{
"created": "Sat, 12 Aug 2023 17:08:28 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Dec 2023 02:54:06 GMT",
"version": "v2"
}
] | 2023-12-07 | [
[
"Yang",
"Ke",
""
],
[
"Chen",
"Yue-Zhe",
""
],
[
"Duan",
"Zheng-Qiao",
""
],
[
"Zhao",
"Ju-Ying",
""
]
] | The Lorentz symmetry of gravity is spontaneously broken when the nonminimally coupled Kalb-Ramond field acquires a nonzero vacuum expectation value. In this work, we present exact solutions for static and spherically symmetric black holes in the framework of this Lorentz-violating gravity theory. In order to explore the physical implications of Lorentz violation, we analyze the thermodynamic properties of the obtained solutions and evaluate the impact of Lorentz violation on some classical gravitational experiments within the Solar System. Furthermore, the Lorentz-violating parameter is constrained by using the measured results of these experiments. |
1705.02133 | Safia Ahmad | Safia Ahmad, R. Myrzakulov, M. Sami | Relic gravitational waves from Quintessential Inflation | 11 pages, 2 figures, major changes, results strengthened in model
independent form, to appear in PRD | Phys. Rev. D 96, 063515 (2017) | 10.1103/PhysRevD.96.063515 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study relic gravitational waves in the paradigm of quintessential
inflation. In this framework, irrespective of the underlying model, inflation
is followed by the kinetic regime. Thereafter, the field energy density remains
sub-dominant before the onset of acceleration. We carry out model independent
analysis to obtain the temperature at the end of inflation and the estimate for
upper bound on the Hubble parameter to circumvent the problem due to relic
gravitational waves. In this process, we used Planck 2015 data to constrain the
inflationary phase. We demonstrate that the required temperature can be
produced by the mechanism of instant preheating. The generic feature of the
scenario includes the presence of kinetic regime after inflation which results
into blue spectrum of gravitational wave background at high frequencies. We
discuss the prospects of detection of relic gravitational wave background in
the advanced LIGO and LISA space-born gravitational wave missions. Finally we
consider a concrete model to realize the paradigm of quintessential inflation
and show that inflationary as well as post-inflationary evolution can
successfully be described by the inflaton potential, $V(\phi) \propto
Exp(-\lambda \phi^n/\Mpl^n)(n>1)$, by suitably constraining the parameters of
the model.
| [
{
"created": "Fri, 5 May 2017 08:51:26 GMT",
"version": "v1"
},
{
"created": "Thu, 24 Aug 2017 08:27:54 GMT",
"version": "v2"
}
] | 2017-09-27 | [
[
"Ahmad",
"Safia",
""
],
[
"Myrzakulov",
"R.",
""
],
[
"Sami",
"M.",
""
]
] | We study relic gravitational waves in the paradigm of quintessential inflation. In this framework, irrespective of the underlying model, inflation is followed by the kinetic regime. Thereafter, the field energy density remains sub-dominant before the onset of acceleration. We carry out model independent analysis to obtain the temperature at the end of inflation and the estimate for upper bound on the Hubble parameter to circumvent the problem due to relic gravitational waves. In this process, we used Planck 2015 data to constrain the inflationary phase. We demonstrate that the required temperature can be produced by the mechanism of instant preheating. The generic feature of the scenario includes the presence of kinetic regime after inflation which results into blue spectrum of gravitational wave background at high frequencies. We discuss the prospects of detection of relic gravitational wave background in the advanced LIGO and LISA space-born gravitational wave missions. Finally we consider a concrete model to realize the paradigm of quintessential inflation and show that inflationary as well as post-inflationary evolution can successfully be described by the inflaton potential, $V(\phi) \propto Exp(-\lambda \phi^n/\Mpl^n)(n>1)$, by suitably constraining the parameters of the model. |
1012.4707 | Carlo Rovelli | Carlo Rovelli | Loop quantum gravity: the first twenty five years | 24 pages, 3 figures | Classical and Quantum Gravity, 28 (2011) 153002 | 10.1088/0264-9381/28/15/153002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This is a review paper invited by the journal "Classical ad Quantum Gravity"
for a "Cluster Issue" on approaches to quantum gravity. I give a synthetic
presentation of loop gravity. I spell-out the aims of the theory and compare
the results obtained with the initial hopes that motivated the early interest
in this research direction. I give my own perspective on the status of the
program and attempt of a critical evaluation of its successes and limits.
| [
{
"created": "Tue, 21 Dec 2010 15:53:38 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Dec 2010 11:47:30 GMT",
"version": "v2"
},
{
"created": "Thu, 23 Dec 2010 10:57:47 GMT",
"version": "v3"
},
{
"created": "Tue, 25 Jan 2011 08:56:34 GMT",
"version": "v4"
},
{
"created": "Sat, 28 Jan 2012 15:32:03 GMT",
"version": "v5"
}
] | 2015-05-20 | [
[
"Rovelli",
"Carlo",
""
]
] | This is a review paper invited by the journal "Classical ad Quantum Gravity" for a "Cluster Issue" on approaches to quantum gravity. I give a synthetic presentation of loop gravity. I spell-out the aims of the theory and compare the results obtained with the initial hopes that motivated the early interest in this research direction. I give my own perspective on the status of the program and attempt of a critical evaluation of its successes and limits. |
2203.14319 | Charis Anastopoulos | Eirini Sourtzinou and Charis Anastopoulos | Quantum statistical mechanics near a black hole horizon | 31 pages, 4 figures; restructured with minor revisions; to appear in
PRD | Phys. Rev. D 107, 085006 (2023) | 10.1103/PhysRevD.107.085006 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We undertake a first-principles analysis of the thermodynamics of a small
body near a black hole horizon. In particular, we study the paradigmatic system
of a quantum ideal gas in a small box hovering over the Schwarzschild horizon.
We describe the gas in terms of free quantum fields, bosonic and fermionic,
massive and massless. We identify thermodynamic properties through the
microcanonical distribution. We first analyse the more general case of a box in
Rindler spacetime, and then specialize to the black hole case. The physics
depends strongly on the distance of the box from the horizon, which we treat as
a macroscopic thermodynamic variable. We find that the effective dimension of
the system transitions from three-dimensional to two-dimensional as we approach
the horizon, that Bekenstein's bound fails when the box is adiabatically
lowered towards the black hole, and that the pressure is highly anisotropic.
The pressure difference between the upper and lower wall leads to an effective
force that must be added to the gravitational acceleration. We also show that
the approximation of quantum fields propagating on a fixed background for
matter breaks down when the system is brought to microscopic distances from the
horizon, in which case backreaction effects must be included.
| [
{
"created": "Sun, 27 Mar 2022 14:40:00 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Oct 2022 16:53:14 GMT",
"version": "v2"
},
{
"created": "Thu, 16 Mar 2023 12:37:11 GMT",
"version": "v3"
}
] | 2024-01-17 | [
[
"Sourtzinou",
"Eirini",
""
],
[
"Anastopoulos",
"Charis",
""
]
] | We undertake a first-principles analysis of the thermodynamics of a small body near a black hole horizon. In particular, we study the paradigmatic system of a quantum ideal gas in a small box hovering over the Schwarzschild horizon. We describe the gas in terms of free quantum fields, bosonic and fermionic, massive and massless. We identify thermodynamic properties through the microcanonical distribution. We first analyse the more general case of a box in Rindler spacetime, and then specialize to the black hole case. The physics depends strongly on the distance of the box from the horizon, which we treat as a macroscopic thermodynamic variable. We find that the effective dimension of the system transitions from three-dimensional to two-dimensional as we approach the horizon, that Bekenstein's bound fails when the box is adiabatically lowered towards the black hole, and that the pressure is highly anisotropic. The pressure difference between the upper and lower wall leads to an effective force that must be added to the gravitational acceleration. We also show that the approximation of quantum fields propagating on a fixed background for matter breaks down when the system is brought to microscopic distances from the horizon, in which case backreaction effects must be included. |
0912.5490 | Natalia Kiriushcheva | N. Kiriushcheva and S.V. Kuzmin | Darboux coordinates for the Hamiltonian of first order Einstein-Cartan
gravity | 44 pages, references are added, organization of material is slightly
modified (additional section is introduced), more details of calculation of
the Dirac bracket between translational and rotational constraints are
provided | Int.J.Theor.Phys.49:2859-2890,2010 | 10.1007/s10773-010-0479-y | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on preliminary analysis of the Hamiltonian formulation of the first
order Einstein-Cartan action (arXiv:0902.0856 [gr-qc] and arXiv:0907.1553
[gr-qc]) we derive the Darboux coordinates, which are a unique and uniform
change of variables preserving equivalence with the original action in all
spacetime dimensions higher than two. Considerable simplification of the
Hamiltonian formulation using the Darboux coordinates, compared with direct
analysis, is explicitly demonstrated. Even an incomplete Hamiltonian analysis
in combination with known symmetries of the Einstein-Cartan action and the
equivalence of Hamiltonian and Lagrangian formulations allows us to
unambiguously conclude that the \textit{unique} \textit{gauge} invariances
generated by the first class constraints of the Einstein-Cartan action and the
corresponding Hamiltonian are \textit{translation and rotation in the tangent
space}. Diffeomorphism invariance, though a manifest invariance of the action,
is not generated by the first class constraints of the theory.
| [
{
"created": "Wed, 30 Dec 2009 17:25:30 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Mar 2010 15:50:37 GMT",
"version": "v2"
}
] | 2014-11-20 | [
[
"Kiriushcheva",
"N.",
""
],
[
"Kuzmin",
"S. V.",
""
]
] | Based on preliminary analysis of the Hamiltonian formulation of the first order Einstein-Cartan action (arXiv:0902.0856 [gr-qc] and arXiv:0907.1553 [gr-qc]) we derive the Darboux coordinates, which are a unique and uniform change of variables preserving equivalence with the original action in all spacetime dimensions higher than two. Considerable simplification of the Hamiltonian formulation using the Darboux coordinates, compared with direct analysis, is explicitly demonstrated. Even an incomplete Hamiltonian analysis in combination with known symmetries of the Einstein-Cartan action and the equivalence of Hamiltonian and Lagrangian formulations allows us to unambiguously conclude that the \textit{unique} \textit{gauge} invariances generated by the first class constraints of the Einstein-Cartan action and the corresponding Hamiltonian are \textit{translation and rotation in the tangent space}. Diffeomorphism invariance, though a manifest invariance of the action, is not generated by the first class constraints of the theory. |
1901.03413 | Lior M. Burko | Lior M. Burko and Gaurav Khanna | The Marolf-Ori singularity inside fast spinning black holes | null | Phys. Rev. D 99, 081501 (2019) | 10.1103/PhysRevD.99.081501 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The effective shock wave singularity at the outgoing leg of the inner horizon
of a linearly perturbed fast spinning black hole is studied numerically for
either scalar field, or vacuum, gravitational perturbations. We demonstrate the
occurrence of the Marolf-Ori singularity, including changes of order unity in
the scalar field $\phi$ for the scalar field model, and in the Weyl scalars
$\psi_0$ and $\psi_4$ (rescaled appropriately by the horizon function $\Delta$)
and the Kretschmann curvature scalar $K$ for the vacuum, gravitational
perturbations model for both null and timelike geodesic observers. We quantify
the shock sharpening effect and show that in all cases its rate agrees with
expectations.
| [
{
"created": "Thu, 10 Jan 2019 22:04:59 GMT",
"version": "v1"
}
] | 2019-05-08 | [
[
"Burko",
"Lior M.",
""
],
[
"Khanna",
"Gaurav",
""
]
] | The effective shock wave singularity at the outgoing leg of the inner horizon of a linearly perturbed fast spinning black hole is studied numerically for either scalar field, or vacuum, gravitational perturbations. We demonstrate the occurrence of the Marolf-Ori singularity, including changes of order unity in the scalar field $\phi$ for the scalar field model, and in the Weyl scalars $\psi_0$ and $\psi_4$ (rescaled appropriately by the horizon function $\Delta$) and the Kretschmann curvature scalar $K$ for the vacuum, gravitational perturbations model for both null and timelike geodesic observers. We quantify the shock sharpening effect and show that in all cases its rate agrees with expectations. |
2001.02543 | Karthik Rajeev | Karthik Rajeev | Complex time route to quantum backreaction | 23 pages, 2 figures, published version | null | 10.1140/epjc/s10052-019-7480-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the backreaction of a quantum system $q$ on an effectively
classical degree of freedom $C$ that is interacting with it. The backreaction
equation based on the standard path integral formalism gives the so-called
`in-out' backreaction equation, which has several serious pathologies. One can
use a different backreaction prescription, referred to as the `in-in' approach,
which resolves all the issues of `in-out' backreaction equation. However, this
procedure is usually invoked in a rather ad hoc manner. Here we provide a
rigorous path integral derivation of the `in-in' approach by exploiting the
concept of quantum evolution along complex time contours. It turns out that,
this approach can also be used to study both the `in-in' and `in-out'
backreaction equations in a unified manner.
| [
{
"created": "Wed, 8 Jan 2020 14:20:10 GMT",
"version": "v1"
}
] | 2020-01-09 | [
[
"Rajeev",
"Karthik",
""
]
] | We consider the backreaction of a quantum system $q$ on an effectively classical degree of freedom $C$ that is interacting with it. The backreaction equation based on the standard path integral formalism gives the so-called `in-out' backreaction equation, which has several serious pathologies. One can use a different backreaction prescription, referred to as the `in-in' approach, which resolves all the issues of `in-out' backreaction equation. However, this procedure is usually invoked in a rather ad hoc manner. Here we provide a rigorous path integral derivation of the `in-in' approach by exploiting the concept of quantum evolution along complex time contours. It turns out that, this approach can also be used to study both the `in-in' and `in-out' backreaction equations in a unified manner. |
gr-qc/0409072 | Friedrich W. Hehl | Claus L\"ammerzahl (1), Friedrich W. Hehl (2,3) ((1) Bremen, (2)
Cologne, (3) Missouri-Columbia) | Riemannian light cone from vanishing birefringence in premetric vacuum
electrodynamics | 12 pages latex | Phys.Rev. D70 (2004) 105022 | 10.1103/PhysRevD.70.105022 | null | gr-qc | null | We consider premetric electrodynamics with a local and linear constitutive
law for the vacuum. Within this framework, we find quartic Fresnel wave
surfaces for the propagation of light. If we require vanishing birefringence in
vacuum, then a Riemannian light cone is implied. No proper Finslerian structure
can occur. This is generalized to dynamical equations of any order.
| [
{
"created": "Sun, 19 Sep 2004 21:17:27 GMT",
"version": "v1"
},
{
"created": "Mon, 22 Nov 2004 23:24:20 GMT",
"version": "v2"
}
] | 2016-08-16 | [
[
"Lämmerzahl",
"Claus",
""
],
[
"Hehl",
"Friedrich W.",
""
]
] | We consider premetric electrodynamics with a local and linear constitutive law for the vacuum. Within this framework, we find quartic Fresnel wave surfaces for the propagation of light. If we require vanishing birefringence in vacuum, then a Riemannian light cone is implied. No proper Finslerian structure can occur. This is generalized to dynamical equations of any order. |
1701.05750 | Timothy Clifton | Timothy Clifton, Bernard Carr, Alan Coley | Persistent Black Holes in Bouncing Cosmologies | 37 pages, 16 figures | Class. Quantum Grav. 34 (2017) 135005 | 10.1088/1361-6382/aa6dbb | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we explore the idea that black holes can persist in a universe
that collapses to a big crunch and then bounces into a new phase of expansion.
We use a scalar field to model the matter content of such a universe {near the
time} of the bounce, and look for solutions that represent a network of black
holes within a dynamical cosmology. We find exact solutions to Einstein's
constraint equations that provide the geometry of space at the minimum of
expansion and that can be used as initial data for the evolution of
hyperspherical cosmologies. These solutions illustrate that there exist models
in which multiple distinct black holes can persist through a bounce, and allow
for concrete computations of quantities such as the black hole filling factor.
We then consider solutions in flat cosmologies, as well as in
higher-dimensional spaces (with up to nine spatial dimensions). We derive
conditions for the black holes to remain distinct (i.e. avoid merging) and
hence persist into the new expansion phase. Some potentially interesting
consequences of these models are also discussed.
| [
{
"created": "Fri, 20 Jan 2017 10:38:52 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Jun 2017 09:34:30 GMT",
"version": "v2"
}
] | 2017-06-28 | [
[
"Clifton",
"Timothy",
""
],
[
"Carr",
"Bernard",
""
],
[
"Coley",
"Alan",
""
]
] | In this paper we explore the idea that black holes can persist in a universe that collapses to a big crunch and then bounces into a new phase of expansion. We use a scalar field to model the matter content of such a universe {near the time} of the bounce, and look for solutions that represent a network of black holes within a dynamical cosmology. We find exact solutions to Einstein's constraint equations that provide the geometry of space at the minimum of expansion and that can be used as initial data for the evolution of hyperspherical cosmologies. These solutions illustrate that there exist models in which multiple distinct black holes can persist through a bounce, and allow for concrete computations of quantities such as the black hole filling factor. We then consider solutions in flat cosmologies, as well as in higher-dimensional spaces (with up to nine spatial dimensions). We derive conditions for the black holes to remain distinct (i.e. avoid merging) and hence persist into the new expansion phase. Some potentially interesting consequences of these models are also discussed. |
1908.11170 | null | The LIGO Scientific Collaboration and the Virgo Collaboration: B. P.
Abbott, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C.
Adams, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D.
Aguiar, L. Aiello, A. Ain, P. Ajith, T. Alford, G. Allen, A. Allocca, M. A.
Aloy, P. A. Altin, A. Amato, A. Ananyeva, S. B. Anderson, W. G. Anderson, S.
V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M.
Ar\`ene, N. Arnaud, K. G. Arun, S. Ascenzi, G. Ashton, S. M. Aston, P.
Astone, F. Aubin, P. Aufmuth, K. AultONeal, C. Austin, V. Avendano, A.
Avila-Alvarez, S. Babak, P. Bacon, F. Badaracco, 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, K. Barkett, S. Barnum, F.
Barone, B. Barr, L. Barsotti, M. Barsuglia, D. Barta, J. Bartlett, I. Bartos,
R. Bassiri, A. Basti, M. Bawaj, J. C. Bayley, M. Bazzan, B. B\'ecsy, M.
Bejger, I. Belahcene, A. S. Bell, D. Beniwal, B. K. Berger, G. Bergmann, S.
Bernuzzi, J. J. Bero, C. P. L. Berry, D. Bersanetti, A. Bertolini, J.
Betzwieser, R. Bhandare, J. Bidler, I. A. Bilenko, S. A. Bilgili, G.
Billingsley, J. Birch, R. Birney, O. Birnholtz, S. Biscans, S. Biscoveanu, A.
Bisht, M. Bitossi, M. A. Bizouard, J. K. Blackburn, C. D. Blair, D. G. Blair,
R. M. Blair, S. Bloemen, N. Bode, M. Boer, Y. Boetzel, G. Bogaert, F. Bondu,
E. Bonilla, R. Bonnand, P. Booker, B. A. Boom, C. D. Booth, R. Bork, V.
Boschi, S. Bose, K. Bossie, V. Bossilkov, J. Bosveld, Y. Bouffanais, A.
Bozzi, C. Bradaschia, P. R. Brady, A. Bramley, M. Branchesi, J. E. Brau, T.
Briant, J. H. Briggs, F. Brighenti, A. Brillet, M. Brinkmann, V. Brisson, P.
Brockill, A. F. Brooks, D. D. Brown, S. Brunett, A. Buikema, T. 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, W. A. Campbell, M. Canepa, K. C. Cannon, H. Cao, J. Cao,
E. Capocasa, F. Carbognani, S. Caride, M. F. Carney, G. Carullo, J. Casanueva
Diaz, C. Casentini, S. Caudill, M. Cavagli\`a, F. Cavalier, R. Cavalieri, G.
Cella, P. Cerd\'a-Dur\'an, G. Cerretani, E. Cesarini, O. Chaibi, K.
Chakravarti, S. J. Chamberlin, M. Chan, S. Chao, P. Charlton, E. A. Chase, E.
Chassande-Mottin, D. Chatterjee, M. Chaturvedi, K. Chatziioannou, B. D.
Cheeseboro, H. Y. Chen, X. Chen, Y. Chen, H.-P. Cheng, C. K. Cheong, H. Y.
Chia, A. Chincarini, A. Chiummo, G. Cho, H. S. Cho, M. Cho, N. Christensen,
Q. Chu, S. Chua, K. W. Chung, S. Chung, G. Ciani, A. A. Ciobanu, R. Ciolfi,
F. Cipriano, A. Cirone, F. Clara, J. A. Clark, P. Clearwater, F. Cleva, C.
Cocchieri, E. Coccia, P.-F. Cohadon, D. Cohen, R. Colgan, M. Colleoni, C. G.
Collette, C. Collins, L. R. Cominsky, M. Constancio Jr., L. Conti, S. J.
Cooper, P. Corban, T. R. Corbitt, I. Cordero-Carri\'on, K. R. Corley, N.
Cornish, A. Corsi, S. Cortese, C. A. Costa, R. Cotesta, M. W. Coughlin, S. B.
Coughlin, J.-P. Coulon, S. T. Countryman, P. Couvares, P. B. Covas, E. E.
Cowan, D. M. Coward, M. J. Cowart, D. C. Coyne, R. Coyne, J. D. E. Creighton,
T. D. Creighton, J. Cripe, M. Croquette, S. G. Crowder, T. J. Cullen, A.
Cumming, L. Cunningham, E. Cuoco, T. Dal Canton, G. D\'alya, S. L.
Danilishin, S. D'Antonio, K. Danzmann, A. Dasgupta, C. F. Da Silva Costa, L.
E. H. Datrier, V. Dattilo, I. Dave, M. Davier, D. Davis, E. J. Daw, D. DeBra,
M. Deenadayalan, J. Degallaix, M. De Laurentis, S. Del\'eglise, W. Del Pozzo,
L. M. DeMarchi, N. Demos, T. Dent, R. De Pietri, J. Derby, R. De Rosa, C. De
Rossi, R. DeSalvo, O. de Varona, S. Dhurandhar, M. C. D\'iaz, T. Dietrich, L.
Di Fiore, M. Di Giovanni, T. Di Girolamo, A. Di Lieto, B. Ding, S. Di Pace,
I. Di Palma, F. Di Renzo, A. Dmitriev, Z. Doctor, F. Donovan, K. L. Dooley,
S. Doravari, I. Dorrington, T. P. Downes, M. Drago, J. C. Driggers, Z. Du,
J.-G. Ducoin, P. Dupej, S. E. Dwyer, P. J. Easter, T. B. Edo, M. C. Edwards,
A. Effler, P. Ehrens, J. Eichholz, S. S. Eikenberry, M. Eisenmann, R. A.
Eisenstein, R. C. Essick, H. Estelles, D. Estevez, Z. B. Etienne, T. Etzel,
M. Evans, T. M. Evans, V. Fafone, H. Fair, S. Fairhurst, X. Fan, S. Farinon,
B. Farr, W. M. Farr, E. J. Fauchon-Jones, M. Favata, M. Fays, M. Fazio, C.
Fee, J. Feicht, M. M. Fejer, F. Feng, A. Fernandez-Galiana, I. Ferrante, E.
C. Ferreira, T. A. Ferreira, F. Ferrini, F. Fidecaro, I. Fiori, D. Fiorucci,
M. Fishbach, R. P. Fisher, J. M. Fishner, M. Fitz-Axen, R. Flaminio, M.
Fletcher, E. Flynn, H. Fong, J. A. Font, P. W. F. Forsyth, J.-D. Fournier, S.
Frasca, F. Frasconi, Z. Frei, A. Freise, R. Frey, V. Frey, P. Fritschel, V.
V. Frolov, P. Fulda, M. Fyffe, H. A. Gabbard, B. U. Gadre, S. M. Gaebel, J.
R. Gair, L. Gammaitoni, M. R. Ganija, S. G. Gaonkar, A. Garcia, C.
Garc\'ia-Quir\'os, F. Garufi, B. Gateley, S. Gaudio, G. Gaur, V. Gayathri, G.
Gemme, E. Genin, A. Gennai, D. George, J. George, L. Gergely, V. Germain, S.
Ghonge, Abhirup Ghosh, Archisman Ghosh, S. Ghosh, B. Giacomazzo, J. A.
Giaime, K. D. Giardina, A. Giazotto, K. Gill, G. Giordano, L. Glover, P.
Godwin, E. Goetz, R. Goetz, B. Goncharov, G. Gonz\'alez, J. M. Gonzalez
Castro, A. Gopakumar, M. L. Gorodetsky, S. E. Gossan, M. Gosselin, R. Gouaty,
A. Grado, C. Graef, M. Granata, A. Grant, S. Gras, P. Grassia, C. Gray, R.
Gray, G. Greco, A. C. Green, R. Green, E. M. Gretarsson, P. Groot, H. Grote,
S. Grunewald, P. Gruning, G. M. Guidi, H. K. Gulati, Y. Guo, A. Gupta, M. K.
Gupta, E. K. Gustafson, R. Gustafson, L. Haegel, O. Halim, B. R. Hall, E. D.
Hall, E. Z. Hamilton, G. Hammond, M. Haney, M. M. Hanke, J. Hanks, C. Hanna,
M. D. Hannam, O. A. Hannuksela, J. Hanson, T. Hardwick, K. Haris, J. Harms,
G. M. Harry, I. W. Harry, C.-J. Haster, K. Haughian, F. J. Hayes, J. Healy,
A. Heidmann, M. C. Heintze, H. Heitmann, P. Hello, G. Hemming, M. Hendry, I.
S. Heng, J. Hennig, A. W. Heptonstall, Francisco Hernandez Vivanco, M. Heurs,
S. Hild, T. Hinderer, D. Hoak, S. Hochheim, D. Hofman, A. M. Holgado, N. A.
Holland, K. Holt, D. E. Holz, P. Hopkins, C. Horst, J. Hough, E. J. Howell,
C. G. Hoy, A. Hreibi, E. A. Huerta, D. Huet, B. Hughey, M. Hulko, S. Husa, S.
H. Huttner, T. Huynh-Dinh, B. Idzkowski, A. Iess, C. Ingram, R. Inta, G.
Intini, B. Irwin, H. N. Isa, J.-M. Isac, M. Isi, B. R. Iyer, K. Izumi, T.
Jacqmin, S. J. Jadhav, K. Jani, N. N. Janthalur, P. Jaranowski, A. C.
Jenkins, J. Jiang, D. S. Johnson, A. W. Jones, D. I. Jones, R. Jones, R. J.
G. Jonker, L. Ju, J. Junker, C. V. Kalaghatgi, V. Kalogera, B. Kamai, S.
Kandhasamy, G. Kang, J. B. Kanner, S. J. Kapadia, S. Karki, K. S. Karvinen,
R. Kashyap, M. Kasprzack, S. Katsanevas, E. Katsavounidis, W. Katzman, S.
Kaufer, K. Kawabe, N. V. Keerthana, F. K\'ef\'elian, D. Keitel, R. Kennedy,
J. S. Key, F. Y. Khalili, H. Khan, I. Khan, S. Khan, Z. Khan, E. A. Khazanov,
M. Khursheed, N. Kijbunchoo, A. X. Kim, Chunglee Kim, J. C. Kim, K. Kim, W.
Kim, W. S. Kim, Y.-M. Kim, C. Kimball, E. J. King, P. J. King, M.
Kinley-Hanlon, R. Kirchhoff, J. S. Kissel, L. Kleybolte, J. H. Klika, S.
Klimenko, T. D. Knowles, P. Koch, S. M. Koehlenbeck, G. Koekoek, S. Koley, V.
Kondrashov, A. Kontos, N. Koper, M. Korobko, W. Z. Korth, I. Kowalska, D. B.
Kozak, V. Kringel, N. Krishnendu, A. Kr\'olak, G. Kuehn, A. Kumar, P. Kumar,
R. Kumar, S. Kumar, L. Kuo, A. Kutynia, S. Kwang, B. D. Lackey, K. H. Lai, T.
L. Lam, M. Landry, B. B. Lane, R. N. Lang, J. Lange, B. Lantz, R. K. Lanza,
S. Larson, A. Lartaux-Vollard, P. D. Lasky, M. Laxen, A. Lazzarini, C.
Lazzaro, P. Leaci, S. Leavey, Y. K. Lecoeuche, C. H. Lee, H. K. Lee, H. M.
Lee, H. W. Lee, J. Lee, K. Lee, J. Lehmann, A. Lenon, N. Leroy, N. Letendre,
Y. Levin, J. Li, K. J. L. Li, T. G. F. Li, X. Li, F. Lin, F. Linde, S. D.
Linker, T. B. Littenberg, J. Liu, X. Liu, R. K. L. Lo, N. A. Lockerbie, L. T.
London, A. Longo, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. D.
Lough, C. O. Lousto, G. Lovelace, M. E. Lower, H. L\"uck, D. Lumaca, A. P.
Lundgren, R. Lynch, Y. Ma, R. Macas, S. Macfoy, M. MacInnis, D. M. Macleod,
A. Macquet, F. Maga\~na-Sandoval, L. Maga\~na Zertuche, R. M. Magee, E.
Majorana, I. Maksimovic, A. Malik, N. Man, V. Mandic, V. Mangano, G. L.
Mansell, M. Manske, M. Mantovani, F. Marchesoni, F. Marion, S. M\'arka, Z.
M\'arka, C. Markakis, A. S. Markosyan, A. Markowitz, E. Maros, A. Marquina,
S. Marsat, F. Martelli, I. W. Martin, R. M. Martin, D. V. Martynov, K. Mason,
E. Massera, A. Masserot, T. J. Massinger, M. Masso-Reid, S. Mastrogiovanni,
A. Matas, F. Matichard, L. Matone, N. Mavalvala, N. Mazumder, J. J. McCann,
R. McCarthy, D. E. McClelland, S. McCormick, L. McCuller, S. C. McGuire, J.
McIver, D. J. McManus, T. McRae, S. T. McWilliams, D. Meacher, G. D. Meadors,
M. Mehmet, A. K. Mehta, J. Meidam, A. Melatos, G. Mendell, R. A. Mercer, L.
Mereni, E. L. Merilh, M. Merzougui, S. Meshkov, C. Messenger, C. Messick, R.
Metzdorff, P. M. Meyers, H. Miao, C. Michel, H. Middleton, E. E. Mikhailov,
L. Milano, A. L. Miller, A. Miller, M. Millhouse, J. C. Mills, M. C.
Milovich-Goff, O. Minazzoli, Y. Minenkov, A. Mishkin, C. Mishra, T. Mistry,
S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, G. Mo, D. Moffa,
K. Mogushi, S. R. P. Mohapatra, M. Montani, C. J. Moore, D. Moraru, G.
Moreno, S. Morisaki, B. Mours, C. M. Mow-Lowry, Arunava Mukherjee, D.
Mukherjee, S. Mukherjee, N. Mukund, A. Mullavey, J. Munch, E. A. Mu\~niz, M.
Muratore, P. G. Murray, A. Nagar, I. Nardecchia, L. Naticchioni, R. K. Nayak,
J. Neilson, G. Nelemans, T. J. N. Nelson, M. Nery, A. Neunzert, K. Y. Ng, S.
Ng, P. Nguyen, D. Nichols, S. Nissanke, F. Nocera, C. North, L. K. Nuttall,
M. Obergaulinger, J. Oberling, B. D. O'Brien, G. D. O'Dea, G. H. Ogin, J. J.
Oh, S. H. Oh, F. Ohme, H. Ohta, M. A. Okada, M. Oliver, P. Oppermann, Richard
J. Oram, B. O'Reilly, R. G. Ormiston, L. F. Ortega, R. O'Shaughnessy, S.
Ossokine, D. J. Ottaway, H. Overmier, B. J. Owen, A. E. Pace, G. Pagano, M.
A. Page, A. Pai, S. A. Pai, J. R. Palamos, O. Palashov, C. Palomba, A.
Pal-Singh, Huang-Wei Pan, B. Pang, P. T. H. Pang, C. Pankow, F. Pannarale, B.
C. Pant, F. Paoletti, A. Paoli, A. Parida, W. Parker, D. Pascucci, A.
Pasqualetti, R. Passaquieti, D. Passuello, M. Patil, B. Patricelli, B. L.
Pearlstone, C. Pedersen, M. Pedraza, R. Pedurand, A. Pele, S. Penn, C. J.
Perez, A. Perreca, H. P. Pfeiffer, M. Phelps, K. S. Phukon, O. J. Piccinni,
M. Pichot, F. Piergiovanni, G. Pillant, L. Pinard, M. Pirello, M. Pitkin, R.
Poggiani, D. Y. T. Pong, S. Ponrathnam, P. Popolizio, E. K. Porter, J.
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Quintero, R. Quitzow-James, F. J. Raab, H. Radkins, N. Radulescu, P. Raffai,
S. Raja, C. Rajan, B. Rajbhandari, M. Rakhmanov, K. E. Ramirez, A.
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Schale, M. Scheel, J. Scheuer, P. Schmidt, R. Schnabel, R. M. S. Schofield,
A. Sch\"onbeck, E. Schreiber, B. W. Schulte, B. F. Schutz, S. G. Schwalbe, J.
Scott, S. M. Scott, E. Seidel, D. Sellers, A. S. Sengupta, N. Sennett, D.
Sentenac, V. Sequino, A. Sergeev, Y. Setyawati, D. A. Shaddock, T. Shaffer,
M. S. Shahriar, M. B. Shaner, L. Shao, P. Sharma, P. Shawhan, H. Shen, R.
Shink, D. H. Shoemaker, D. M. Shoemaker, S. ShyamSundar, K. Siellez, M.
Sieniawska, D. Sigg, A. D. Silva, L. P. Singer, N. Singh, A. Singhal, A. M.
Sintes, S. Sitmukhambetov, V. Skliris, B. J. J. Slagmolen, T. J.
Slaven-Blair, J. R. Smith, R. J. E. Smith, S. Somala, E. J. Son, B. Sorazu,
F. Sorrentino, T. Souradeep, E. Sowell, A. P. Spencer, A. K. Srivastava, V.
Srivastava, K. Staats, C. Stachie, M. Standke, D. A. Steer, M. Steinke, J.
Steinlechner, S. Steinlechner, D. Steinmeyer, S. P. Stevenson, D. Stocks, R.
Stone, D. J. Stops, K. A. Strain, G. Stratta, S. E. Strigin, A. Strunk, R.
Sturani, A. L. Stuver, V. Sudhir, T. Z. Summerscales, L. Sun, S. Sunil, J.
Suresh, P. J. Sutton, B. L. Swinkels, M. J. Szczepa\'nczyk, M. Tacca, S. C.
Tait, C. Talbot, D. Talukder, D. B. Tanner, M. T\'apai, A. Taracchini, J. D.
Tasson, R. Taylor, F. Thies, M. Thomas, P. Thomas, S. R. Thondapu, K. A.
Thorne, E. Thrane, Shubhanshu Tiwari, Srishti Tiwari, V. Tiwari, K. Toland,
M. Tonelli, Z. Tornasi, A. Torres-Forn\'e, C. I. Torrie, D. T\"oyr\"a, F.
Travasso, G. Traylor, M. C. Tringali, A. Trovato, L. Trozzo, R. Trudeau, K.
W. Tsang, M. Tse, R. Tso, L. Tsukada, D. Tsuna, D. Tuyenbayev, K. Ueno, D.
Ugolini, C. S. Unnikrishnan, A. L. Urban, S. A. Usman, H. Vahlbruch, G.
Vajente, G. Valdes, N. van Bakel, M. van Beuzekom, J. F. J. van den Brand, C.
Van Den Broeck, D. C. Vander-Hyde, J. V. van Heijningen, L. van der Schaaf,
A. A. van Veggel, M. Vardaro, V. Varma, S. Vass, M. Vas\'uth, A. Vecchio, G.
Vedovato, J. Veitch, P. J. Veitch, K. Venkateswara, G. Venugopalan, D.
Verkindt, F. Vetrano, A. Vicer\'e, A. D. Viets, D. J. Vine, J.-Y. Vinet, S.
Vitale, T. Vo, H. Vocca, C. Vorvick, 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, W. H. Wang, Y. F. Wang, R. L. Ward, Z. A. Warden, J. Warner, M.
Was, J. Watchi, B. Weaver, L.-W. Wei, M. Weinert, A. J. Weinstein, R. Weiss,
F. Wellmann, L. Wen, E. K. Wessel, P. We{\ss}els, J. W. Westhouse, K. Wette,
J. T. Whelan, B. F. Whiting, C. Whittle, D. M. Wilken, 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. K. Wofford, J. Worden, J. L. Wright, D. S.
Wu, D. M. Wysocki, L. Xiao, H. Yamamoto, C. C. Yancey, L. Yang, M. J. Yap, M.
Yazback, D. W. Yeeles, Hang Yu, Haocun Yu, S. H. R. Yuen, M. Yvert, A. K.
Zadro\.zny, M. Zanolin, T. Zelenova, J.-P. Zendri, M. Zevin, J. Zhang, L.
Zhang, T. Zhang, C. Zhao, M. Zhou, Z. Zhou, X. J. Zhu, M. E. Zucker, J.
Zweizig | A guide to LIGO-Virgo detector noise and extraction of transient
gravitational-wave signals | null | B P Abbott et al 2020 Class. Quantum Grav. 37 055002 | 10.1088/1361-6382/ab685e | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The LIGO Scientific Collaboration and the Virgo Collaboration have cataloged
eleven confidently detected gravitational-wave events during the first two
observing runs of the advanced detector era. All eleven events were consistent
with being from well-modeled mergers between compact stellar-mass objects:
black holes or neutron stars. The data around the time of each of these events
have been made publicly available through the gravitational-wave open science
center. The entirety of the gravitational-wave strain data from the first and
second observing runs have also now been made publicly available. There is
considerable interest among the broad scientific community in understanding the
data and methods used in the analyses. In this paper, we provide an overview of
the detector noise properties and the data analysis techniques used to detect
gravitational-wave signals and infer the source properties. We describe some of
the checks that are performed to validate the analyses and results from the
observations of gravitational-wave events. We also address concerns that have
been raised about various properties of LIGO-Virgo detector noise and the
correctness of our analyses as applied to the resulting data.
| [
{
"created": "Thu, 29 Aug 2019 12:15:16 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Sep 2019 15:22:19 GMT",
"version": "v2"
},
{
"created": "Mon, 10 Feb 2020 21:13:15 GMT",
"version": "v3"
}
] | 2020-02-12 | [
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[
"Warden",
"Z. A.",
""
],
[
"Warner",
"J.",
""
],
[
"Was",
"M.",
""
],
[
"Watchi",
"J.",
""
],
[
"Weaver",
"B.",
""
],
[
"Wei",
"L. -W.",
""
],
[
"Weinert",
"M.",
""
],
[
"Weinstein",
"A. J.",
""
],
[
"Weiss",
"R.",
""
],
[
"Wellmann",
"F.",
""
],
[
"Wen",
"L.",
""
],
[
"Wessel",
"E. K.",
""
],
[
"Weßels",
"P.",
""
],
[
"Westhouse",
"J. W.",
""
],
[
"Wette",
"K.",
""
],
[
"Whelan",
"J. T.",
""
],
[
"Whiting",
"B. F.",
""
],
[
"Whittle",
"C.",
""
],
[
"Wilken",
"D. M.",
""
],
[
"Williams",
"D.",
""
],
[
"Williamson",
"A. R.",
""
],
[
"Willis",
"J. L.",
""
],
[
"Willke",
"B.",
""
],
[
"Wimmer",
"M. H.",
""
],
[
"Winkler",
"W.",
""
],
[
"Wipf",
"C. C.",
""
],
[
"Wittel",
"H.",
""
],
[
"Woan",
"G.",
""
],
[
"Woehler",
"J.",
""
],
[
"Wofford",
"J. K.",
""
],
[
"Worden",
"J.",
""
],
[
"Wright",
"J. L.",
""
],
[
"Wu",
"D. S.",
""
],
[
"Wysocki",
"D. M.",
""
],
[
"Xiao",
"L.",
""
],
[
"Yamamoto",
"H.",
""
],
[
"Yancey",
"C. C.",
""
],
[
"Yang",
"L.",
""
],
[
"Yap",
"M. J.",
""
],
[
"Yazback",
"M.",
""
],
[
"Yeeles",
"D. W.",
""
],
[
"Yu",
"Hang",
""
],
[
"Yu",
"Haocun",
""
],
[
"Yuen",
"S. H. R.",
""
],
[
"Yvert",
"M.",
""
],
[
"Zadrożny",
"A. K.",
""
],
[
"Zanolin",
"M.",
""
],
[
"Zelenova",
"T.",
""
],
[
"Zendri",
"J. -P.",
""
],
[
"Zevin",
"M.",
""
],
[
"Zhang",
"J.",
""
],
[
"Zhang",
"L.",
""
],
[
"Zhang",
"T.",
""
],
[
"Zhao",
"C.",
""
],
[
"Zhou",
"M.",
""
],
[
"Zhou",
"Z.",
""
],
[
"Zhu",
"X. J.",
""
],
[
"Zucker",
"M. E.",
""
],
[
"Zweizig",
"J.",
""
]
] | The LIGO Scientific Collaboration and the Virgo Collaboration have cataloged eleven confidently detected gravitational-wave events during the first two observing runs of the advanced detector era. All eleven events were consistent with being from well-modeled mergers between compact stellar-mass objects: black holes or neutron stars. The data around the time of each of these events have been made publicly available through the gravitational-wave open science center. The entirety of the gravitational-wave strain data from the first and second observing runs have also now been made publicly available. There is considerable interest among the broad scientific community in understanding the data and methods used in the analyses. In this paper, we provide an overview of the detector noise properties and the data analysis techniques used to detect gravitational-wave signals and infer the source properties. We describe some of the checks that are performed to validate the analyses and results from the observations of gravitational-wave events. We also address concerns that have been raised about various properties of LIGO-Virgo detector noise and the correctness of our analyses as applied to the resulting data. |
gr-qc/0002027 | Jorge Pullin | Jorge Pullin | Matters of Gravity, the newsletter of the APS Topical Group on
Gravitation | 35 pages, LaTeX with psfig and html.sty, ISSN 1527-3431, Jorge Pullin
(editor), html, ps and pdf versions at http://gravity.phys.psu.edu/mog.html | null | null | MOG-15 | gr-qc | null | News:
TGG session in the April meeting, by Cliff Will NRC report, by Beverly Berger
MG9 Travel Grant for US researchers, by Jim Isenberg Research Briefs:
How many coalescing binaries are there?, by Vicky Kalogera Recent
developments in black critical phenomena, by Pat Brady Optical black holes?, by
Matt Visser ``Branification:'' an alternative to compactification, by Steve
Giddings Searches for non-Newtonian Gravity at Sub-mm Distances, by Riley
Newman Quiescent cosmological singularities by Bernd Schmidt The debut of LIGO
II, by David Shoemaker Is the universe still accelerating?, by Sean Carroll
Conference reports:
Journ\' ees Relativistes Weimar 1999, by Volker Perlick The 9th Midwest
Relativity Meeting, by Thomas Baumgarte
| [
{
"created": "Mon, 7 Feb 2000 14:28:29 GMT",
"version": "v1"
}
] | 2009-03-10 | [
[
"Pullin",
"Jorge",
""
]
] | News: TGG session in the April meeting, by Cliff Will NRC report, by Beverly Berger MG9 Travel Grant for US researchers, by Jim Isenberg Research Briefs: How many coalescing binaries are there?, by Vicky Kalogera Recent developments in black critical phenomena, by Pat Brady Optical black holes?, by Matt Visser ``Branification:'' an alternative to compactification, by Steve Giddings Searches for non-Newtonian Gravity at Sub-mm Distances, by Riley Newman Quiescent cosmological singularities by Bernd Schmidt The debut of LIGO II, by David Shoemaker Is the universe still accelerating?, by Sean Carroll Conference reports: Journ\' ees Relativistes Weimar 1999, by Volker Perlick The 9th Midwest Relativity Meeting, by Thomas Baumgarte |
gr-qc/0308087 | Alexander Unzicker | Alexander Unzicker | Galaxies as Rotating Buckets - a Hypothesis on the Gravitational
Constant Based on Mach's Principle | 12 pages, LaTeX, 2 figures. Minor corrections, some references added | null | null | null | gr-qc astro-ph | null | According to Mach's principle inertia has its reason in the presence of all
masses in the universe. Despite there is a lot of sympathy for this plausible
idea, only a few quantitative frameworks have been proposed to test it. In this
paper a tentative theory is given which is based on Mach's critisism on
Newton's rotating bucket. Taking this criticism seriously, one is led to the
hypothesis that the rotation of our galaxy is the reason for gravitation.
Concretely, a functional dependence of the gravitational constant on the size,
mass and angular momentum of the milky way is proposed that leads to a spatial,
but not to a temporal variation of G. Since Newton's inverse-square law is
modified, flat rotation curves of galaxies can be explained that usually need
the postulate of dark matter. While the consequences for stellar evolution are
discussed briefly, a couple of further observational coincidences are noted and
possible experimental tests are proposed.
| [
{
"created": "Thu, 28 Aug 2003 18:44:36 GMT",
"version": "v1"
},
{
"created": "Sun, 7 Sep 2003 11:33:23 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Unzicker",
"Alexander",
""
]
] | According to Mach's principle inertia has its reason in the presence of all masses in the universe. Despite there is a lot of sympathy for this plausible idea, only a few quantitative frameworks have been proposed to test it. In this paper a tentative theory is given which is based on Mach's critisism on Newton's rotating bucket. Taking this criticism seriously, one is led to the hypothesis that the rotation of our galaxy is the reason for gravitation. Concretely, a functional dependence of the gravitational constant on the size, mass and angular momentum of the milky way is proposed that leads to a spatial, but not to a temporal variation of G. Since Newton's inverse-square law is modified, flat rotation curves of galaxies can be explained that usually need the postulate of dark matter. While the consequences for stellar evolution are discussed briefly, a couple of further observational coincidences are noted and possible experimental tests are proposed. |
1602.00683 | Michael Good | Michael R.R. Good | Reflections on a Black Mirror | 6 pages, 4 figures, Contribution to the 2nd LeCosPA International
Symposium, "Everything About Gravity", Taipei, Taiwan, 2015 | null | 10.1142/9789813203952_0078 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A black mirror is an accelerated boundary that produces particles in an exact
correspondence to an evaporating black hole. We investigate the spectral
dynamics of the particle creation during the formation process.
| [
{
"created": "Sun, 31 Jan 2016 13:22:12 GMT",
"version": "v1"
},
{
"created": "Sun, 30 Oct 2016 04:18:32 GMT",
"version": "v2"
}
] | 2018-07-27 | [
[
"Good",
"Michael R. R.",
""
]
] | A black mirror is an accelerated boundary that produces particles in an exact correspondence to an evaporating black hole. We investigate the spectral dynamics of the particle creation during the formation process. |
2201.01716 | Oleg Tsupko | Gennady S. Bisnovatyi-Kogan and Oleg Yu. Tsupko | Analytical study of higher-order ring images of accretion disk around
black hole | 14 pages, 7 figures | Phys. Rev. D 105, 064040 (2022) | 10.1103/PhysRevD.105.064040 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational lensing of a light source by a black hole leads to appearance
of higher-order images produced by photons that loop around the black hole
before reaching the observer. Higher-order images were widely investigated
numerically and analytically, in particular using so-called strong deflection
limit of gravitational deflection. After recent observations of the black hole
image, attention has been drawn to higher-order rings, which are lensed images
of the accreting matter of the black hole environment and can appear near the
boundary of the black hole shadow. In this article, we use strong deflection
limit technique to investigate higher-order ring images of luminous accretion
disc around a Schwarzschild black hole. We consider thin disk given by the
inner and outer radii and an observer located far from the black hole on the
axis of symmetry. For this configuration, it becomes possible to find the
angular radii, thicknesses, and solid angles of higher-order rings in the form
of compact analytical expressions. We show that the size of the rings is mainly
determined by the position of the inner boundary of the accretion disk, which
makes it possible to use them to distinguish between different accretion
models. Possible generalizations of our model to non-symmetric images can help
to make the estimation of black hole angular momentum. We also present the
analytical estimation of fluxes from higher-order images. Our method makes it
easy to investigate $n=2$ and $n=3$ higher-order rings, the possible
observation of which in future projects is currently being discussed.
| [
{
"created": "Wed, 5 Jan 2022 17:10:52 GMT",
"version": "v1"
}
] | 2022-09-15 | [
[
"Bisnovatyi-Kogan",
"Gennady S.",
""
],
[
"Tsupko",
"Oleg Yu.",
""
]
] | Gravitational lensing of a light source by a black hole leads to appearance of higher-order images produced by photons that loop around the black hole before reaching the observer. Higher-order images were widely investigated numerically and analytically, in particular using so-called strong deflection limit of gravitational deflection. After recent observations of the black hole image, attention has been drawn to higher-order rings, which are lensed images of the accreting matter of the black hole environment and can appear near the boundary of the black hole shadow. In this article, we use strong deflection limit technique to investigate higher-order ring images of luminous accretion disc around a Schwarzschild black hole. We consider thin disk given by the inner and outer radii and an observer located far from the black hole on the axis of symmetry. For this configuration, it becomes possible to find the angular radii, thicknesses, and solid angles of higher-order rings in the form of compact analytical expressions. We show that the size of the rings is mainly determined by the position of the inner boundary of the accretion disk, which makes it possible to use them to distinguish between different accretion models. Possible generalizations of our model to non-symmetric images can help to make the estimation of black hole angular momentum. We also present the analytical estimation of fluxes from higher-order images. Our method makes it easy to investigate $n=2$ and $n=3$ higher-order rings, the possible observation of which in future projects is currently being discussed. |
1312.7801 | Sharmanthie Fernando | Sharmanthie Fernando | Born-Infeld-de Sitter gravity: Cold, ultracold and Nariai black holes | 12 figures, 17 pages, minor changes, one reference added | International Journal of Modern Physics D 22, 13, 1350080 ( 2013) | 10.1142/S0218271813500806 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we have presented interesting properties of the static charged
Born-Infeld-de Sitter black hole. They can have time-like as well as space-like
singularities depending on the parameters of the theory. The degenerate black
holes lead to cold, ultra cold and Nariai black holes. The geometry of such
black holes are discussed. A comparison is done with the Reissner-Nordstrom-de
Sitter black holes.
| [
{
"created": "Mon, 30 Dec 2013 18:07:30 GMT",
"version": "v1"
},
{
"created": "Sat, 16 Aug 2014 17:29:53 GMT",
"version": "v2"
}
] | 2015-06-18 | [
[
"Fernando",
"Sharmanthie",
""
]
] | In this paper, we have presented interesting properties of the static charged Born-Infeld-de Sitter black hole. They can have time-like as well as space-like singularities depending on the parameters of the theory. The degenerate black holes lead to cold, ultra cold and Nariai black holes. The geometry of such black holes are discussed. A comparison is done with the Reissner-Nordstrom-de Sitter black holes. |
1310.0675 | Ivan Arraut | Ivan Arraut | Can a non-local model of gravity reproduce Dark Matter effects in
agreement with MOND? | Final version to appear in Int. J. Mod. Phys. D | Int. J. Mod. Phys. D 23, No. 1 (2014) | 10.1142/S0218271814500084 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I analyze the possibility of reproducing MONDian Dark Matter effects by using
a non-local model of gravity. The model was used before in order to recreate
screening effects for the Cosmological Constant ($\Lambda$) value. Although the
model in the weak-field approximation (in static coordinates) can reproduce the
field equations in agreement with the AQUAL Lagrangian, the solutions are scale
dependent and cannot reproduce the same dynamics in agreement with MOND.
| [
{
"created": "Wed, 2 Oct 2013 12:18:06 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Oct 2013 15:12:03 GMT",
"version": "v2"
},
{
"created": "Mon, 18 Nov 2013 07:20:59 GMT",
"version": "v3"
}
] | 2013-11-26 | [
[
"Arraut",
"Ivan",
""
]
] | I analyze the possibility of reproducing MONDian Dark Matter effects by using a non-local model of gravity. The model was used before in order to recreate screening effects for the Cosmological Constant ($\Lambda$) value. Although the model in the weak-field approximation (in static coordinates) can reproduce the field equations in agreement with the AQUAL Lagrangian, the solutions are scale dependent and cannot reproduce the same dynamics in agreement with MOND. |
1707.08870 | Raissa Mendes | Raissa F. P. Mendes and Eric Poisson | Swimming in spacetime: the view from a Fermi observer | 11 pages, 2 figures. V2: note added regarding interpretation of
results | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An extended test body moving in a curved spacetime does not typically follow
a geodesic, because of forces that arise from couplings between its multipole
moments and the ambient curvature. An illustration of this fact was provided by
Wisdom, who showed that the motion of a quasi-rigid body undergoing cyclic
changes of shape in a curved spacetime deviates, in general, from a geodesic.
Wisdom's analysis, however, was recently challenged on the grounds that the
body's motion should be described by the Mathisson-Papapetrou-Dixon equations,
and that these predict geodesic motion for the kind of body considered by
Wisdom. We attempt to shed some light on this matter by examining the motion of
an internally-moving tripod in Schwarzschild spacetime, as viewed by a Fermi
observer moving on a timelike geodesic. We find that the description of the
motion depends sensitively on a choice of cycle for the tripod's internal
motions, but also on a choice of "center of mass" for the tripod; a sensible
(though not unique) prescription for this "center of mass" produces a motion
that conforms with Wisdom's prediction: the tripod drifts away from the
observer, even when they are given identical initial conditions. We suggest
pathways of reconciliation between this conclusion and the null result that
apparently follows from the Mathisson-Papapetrou-Dixon equations of motion.
| [
{
"created": "Thu, 27 Jul 2017 14:14:09 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Dec 2017 19:02:41 GMT",
"version": "v2"
}
] | 2017-12-20 | [
[
"Mendes",
"Raissa F. P.",
""
],
[
"Poisson",
"Eric",
""
]
] | An extended test body moving in a curved spacetime does not typically follow a geodesic, because of forces that arise from couplings between its multipole moments and the ambient curvature. An illustration of this fact was provided by Wisdom, who showed that the motion of a quasi-rigid body undergoing cyclic changes of shape in a curved spacetime deviates, in general, from a geodesic. Wisdom's analysis, however, was recently challenged on the grounds that the body's motion should be described by the Mathisson-Papapetrou-Dixon equations, and that these predict geodesic motion for the kind of body considered by Wisdom. We attempt to shed some light on this matter by examining the motion of an internally-moving tripod in Schwarzschild spacetime, as viewed by a Fermi observer moving on a timelike geodesic. We find that the description of the motion depends sensitively on a choice of cycle for the tripod's internal motions, but also on a choice of "center of mass" for the tripod; a sensible (though not unique) prescription for this "center of mass" produces a motion that conforms with Wisdom's prediction: the tripod drifts away from the observer, even when they are given identical initial conditions. We suggest pathways of reconciliation between this conclusion and the null result that apparently follows from the Mathisson-Papapetrou-Dixon equations of motion. |
2408.05142 | Dmitri Fursaev | D.V. Fursaev, E.A.Davydov, I.G. Pirozhenko, V.A.Tainov | Perturbations of classical fields by gravitational shockwaves | 29 pages, 4 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational shockwaves are geometries where components of the transverse
curvature have abrupt behaviour across null hypersurfaces, which are fronts of
the waves. We develop a general approach to describe classical field theories
on such geometries in a linearized approximation, by using free scalar fields
as a model. Perturbations caused by shockwaves exist above the wave front and
are solutions to a characteristic Cauchy problem with initial data on the wave
front determined by a supertranslation of ingoing fields. A special attention
is paid to perturbations of fields of pointlike sources generated by
plane-fronted gravitational shockwaves. One has three effects: conversion of
non-stationary perturbations into an outgoing radiation, a spherical scalar
shockwave which appears when the gravitational wave hits the source, and a
plane scalar shockwave accompanying the initial gravitational wave. Our
analysis is applicable to gravitational shockwaves of a general class including
geometries sourced by null particles and null branes.
| [
{
"created": "Fri, 9 Aug 2024 15:57:02 GMT",
"version": "v1"
}
] | 2024-08-12 | [
[
"Fursaev",
"D. V.",
""
],
[
"Davydov",
"E. A.",
""
],
[
"Pirozhenko",
"I. G.",
""
],
[
"Tainov",
"V. A.",
""
]
] | Gravitational shockwaves are geometries where components of the transverse curvature have abrupt behaviour across null hypersurfaces, which are fronts of the waves. We develop a general approach to describe classical field theories on such geometries in a linearized approximation, by using free scalar fields as a model. Perturbations caused by shockwaves exist above the wave front and are solutions to a characteristic Cauchy problem with initial data on the wave front determined by a supertranslation of ingoing fields. A special attention is paid to perturbations of fields of pointlike sources generated by plane-fronted gravitational shockwaves. One has three effects: conversion of non-stationary perturbations into an outgoing radiation, a spherical scalar shockwave which appears when the gravitational wave hits the source, and a plane scalar shockwave accompanying the initial gravitational wave. Our analysis is applicable to gravitational shockwaves of a general class including geometries sourced by null particles and null branes. |
gr-qc/0601067 | Victor N. Pervushin | V.N. Pervushin and V.A. Zinchuk | Bogoliubov's Integrals of Motion in Quantum Cosmology and Gravity | 12 pages, Proceedings of the II International Conference on
Superintegrable Systems in Classical and Quantum Mechanics, Dubna, Russia,
June 27 - July 1, 2005 (will be published in Yadernaya Fizika, 2006) | Phys.Atom.Nucl.70:593-600,2007 | 10.1134/S1063778807030210 | null | gr-qc | null | Quantum Cosmology and Gravity are formulated here as the primary and
secondary quantizations of the energy constraints by analogy with the
historical formulation of quantum field theory. New fact is that both the
Universe and its matter are created from stable vacuum obtained by the
Bogoliubov-type transformation just as it is in the theory of quantum
superfluid liquid. Such the Quantum Gravity gives us possibility to explain
topical problems of cosmology by the cosmological creation of universes and
particles from vacuum.
| [
{
"created": "Tue, 17 Jan 2006 10:06:38 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Pervushin",
"V. N.",
""
],
[
"Zinchuk",
"V. A.",
""
]
] | Quantum Cosmology and Gravity are formulated here as the primary and secondary quantizations of the energy constraints by analogy with the historical formulation of quantum field theory. New fact is that both the Universe and its matter are created from stable vacuum obtained by the Bogoliubov-type transformation just as it is in the theory of quantum superfluid liquid. Such the Quantum Gravity gives us possibility to explain topical problems of cosmology by the cosmological creation of universes and particles from vacuum. |
0712.3008 | Giovanni Montani | Giovanni Montani, Marco Valerio Battisti, Riccardo Benini, Giovanni
Imponente | Classical and Quantum Features of the Mixmaster Singularity | 170 pages, 14 figures, ~500 references. Invited review paper to
appear on Int. J. Mod. Phys. A. v2: minor changes, references added. v3:
Conclusions added | Int.J.Mod.Phys.A23:2353-2503,2008 | 10.1142/S0217751X08040275 | null | gr-qc astro-ph hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This review article is devoted to analyze the main properties characterizing
the cosmological singularity associated to the homogeneous and inhomogeneous
Mixmaster model. After the introduction of the main tools required to treat the
cosmological issue, we review in details the main results got along the last
forty years on the Mixmaster topic. We firstly assess the classical picture of
the homogeneous chaotic cosmologies and, after a presentation of the canonical
method for the quantization, we develop the quantum Mixmaster behavior.
Finally, we extend both the classical and quantum features to the fully
inhomogeneous case. Our survey analyzes the fundamental framework of the
Mixmaster picture and completes it by accounting for recent and peculiar
outstanding results.
| [
{
"created": "Tue, 18 Dec 2007 17:45:03 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Mar 2008 16:15:11 GMT",
"version": "v2"
},
{
"created": "Fri, 12 Sep 2008 13:24:57 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Montani",
"Giovanni",
""
],
[
"Battisti",
"Marco Valerio",
""
],
[
"Benini",
"Riccardo",
""
],
[
"Imponente",
"Giovanni",
""
]
] | This review article is devoted to analyze the main properties characterizing the cosmological singularity associated to the homogeneous and inhomogeneous Mixmaster model. After the introduction of the main tools required to treat the cosmological issue, we review in details the main results got along the last forty years on the Mixmaster topic. We firstly assess the classical picture of the homogeneous chaotic cosmologies and, after a presentation of the canonical method for the quantization, we develop the quantum Mixmaster behavior. Finally, we extend both the classical and quantum features to the fully inhomogeneous case. Our survey analyzes the fundamental framework of the Mixmaster picture and completes it by accounting for recent and peculiar outstanding results. |
1807.10830 | Ryan Marshman | Ryan J. Marshman, Anupam Mazumdar, Gavin W. Morley, Peter F. Barker,
Steven Hoekstra and Sougato Bose | Mesoscopic Interference for Metric and Curvature (MIMAC) & Gravitational
Wave Detection | 29 pages, 3 figures | New Journal of Physics 22, 083012 (2020) | 10.1088/1367-2630/ab9f6c | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A compact detector for space-time metric and curvature is highly desirable.
Here we show that quantum spatial superpositions of mesoscopic objects, of the
type which would in principle become possible with a combination of state of
the art techniques and taking into account the known sources of decoherence,
could be exploited to create such a detector. By using Stern-Gerlach (SG)
interferometry with masses much larger than atoms, where the interferometric
signal is extracted by measuring spins, we show that accelerations as low as
$5\times10^{-15}\textrm{ms}^{-2}\textrm{Hz}^{-1/2}$ or better, as well as the
frame dragging effects caused by the Earth, could be sensed. Constructing such
an apparatus to be non-symmetric would also enable the direct detection of
curvature and gravitational waves (GWs). The GW sensitivity scales differently
from the stray acceleration sensitivity, a unique feature of MIMAC. We have
identified mitigation mechanisms for the known sources of noise, namely Gravity
Gradient Noise (GGN), uncertainty principle and electro-magnetic forces. Hence
it could potentially lead to a meter sized, orientable and vibrational noise
(thermal/seismic) resilient detector of mid (ground based) and low (space
based) frequency GWs from massive binaries (the predicted regimes are similar
to those targeted by atom interferometers and LISA).
| [
{
"created": "Fri, 27 Jul 2018 20:46:08 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Oct 2018 14:01:40 GMT",
"version": "v2"
},
{
"created": "Sun, 8 Dec 2019 21:54:58 GMT",
"version": "v3"
},
{
"created": "Mon, 8 Jun 2020 09:54:47 GMT",
"version": "v4"
}
] | 2020-08-26 | [
[
"Marshman",
"Ryan J.",
""
],
[
"Mazumdar",
"Anupam",
""
],
[
"Morley",
"Gavin W.",
""
],
[
"Barker",
"Peter F.",
""
],
[
"Hoekstra",
"Steven",
""
],
[
"Bose",
"Sougato",
""
]
] | A compact detector for space-time metric and curvature is highly desirable. Here we show that quantum spatial superpositions of mesoscopic objects, of the type which would in principle become possible with a combination of state of the art techniques and taking into account the known sources of decoherence, could be exploited to create such a detector. By using Stern-Gerlach (SG) interferometry with masses much larger than atoms, where the interferometric signal is extracted by measuring spins, we show that accelerations as low as $5\times10^{-15}\textrm{ms}^{-2}\textrm{Hz}^{-1/2}$ or better, as well as the frame dragging effects caused by the Earth, could be sensed. Constructing such an apparatus to be non-symmetric would also enable the direct detection of curvature and gravitational waves (GWs). The GW sensitivity scales differently from the stray acceleration sensitivity, a unique feature of MIMAC. We have identified mitigation mechanisms for the known sources of noise, namely Gravity Gradient Noise (GGN), uncertainty principle and electro-magnetic forces. Hence it could potentially lead to a meter sized, orientable and vibrational noise (thermal/seismic) resilient detector of mid (ground based) and low (space based) frequency GWs from massive binaries (the predicted regimes are similar to those targeted by atom interferometers and LISA). |
0712.4363 | Andrzej Krolak | Robert J. Budzy\'nski, Witold Kondracki and Andrzej Kr\'olak | Applications of distance between probability distributions to
gravitational wave data analysis | 18 pages, 5 figures | Class.Quant.Grav.25:015005,2008 | 10.1088/0264-9381/25/1/015005 | null | gr-qc | null | We present a definition of the distance between probability distributions.
Our definition is based on the $L_1$ norm on space of probability measures. We
compare our distance with the well-known Kullback-Leibler divergence and with
the proper distance defined using the Fisher matrix as a metric on the
parameter space. We consider using our notion of distance in several problems
in gravitational wave data analysis: to place templates in the parameter space
in searches for gravitational-wave signals, to assess quality of search
templates, and to study the signal resolution.
| [
{
"created": "Fri, 28 Dec 2007 15:15:14 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Budzyński",
"Robert J.",
""
],
[
"Kondracki",
"Witold",
""
],
[
"Królak",
"Andrzej",
""
]
] | We present a definition of the distance between probability distributions. Our definition is based on the $L_1$ norm on space of probability measures. We compare our distance with the well-known Kullback-Leibler divergence and with the proper distance defined using the Fisher matrix as a metric on the parameter space. We consider using our notion of distance in several problems in gravitational wave data analysis: to place templates in the parameter space in searches for gravitational-wave signals, to assess quality of search templates, and to study the signal resolution. |
gr-qc/0101018 | Jonathan Wilson | J. A. Vickers and J. P. Wilson (Department of Mathematics, University
of Southampton) | Generalised hyperbolicity: hypersurface singularities | 9 pages, AmSTeX, 2 postscript figures | null | null | null | gr-qc | null | Sufficient conditions for the well-posedness of the initial value problem for
the scalar wave equation are obtained in space-times with hypersurface
singularities
| [
{
"created": "Fri, 5 Jan 2001 10:16:34 GMT",
"version": "v1"
}
] | 2009-09-25 | [
[
"Vickers",
"J. A.",
"",
"Department of Mathematics, University\n of Southampton"
],
[
"Wilson",
"J. P.",
"",
"Department of Mathematics, University\n of Southampton"
]
] | Sufficient conditions for the well-posedness of the initial value problem for the scalar wave equation are obtained in space-times with hypersurface singularities |
gr-qc/0211108 | Lorenzo Iorio | Herbert I.M. Lichtenegger, Lorenzo Iorio, Bahram Mashhoon | The gravitomagnetic clock effect and its possible observation | LaTex2e, 9 pages, no tables, 2 figures, 18 references. Paper
presented at COSPAR 2002 assembly held in Houston, Texas, 10 October 2002-19
October 2002. Expanded version published in Annalen der Physik | AnnalenPhys.15:868-876,2006 | 10.1002/andp.200610214 | null | gr-qc astro-ph | null | The general relativistic gravitomagnetic clock effect involves a coupling
between the orbital motion of a test particle and the rotation of the central
mass and results in a difference in the proper periods of two counter-revolving
satellites. It is shown that at O(c^-2) this effect has a simple analogue in
the electromagnetic case. Moreover, in view of a possible measurement of the
clock effect in the gravitational field of the Earth, we investigate the
influence of some classical perturbing forces of the terrestrial space
environment on the orbital motion of test bodies along opposite trajectories.
| [
{
"created": "Fri, 29 Nov 2002 17:08:41 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Dec 2002 16:16:18 GMT",
"version": "v2"
},
{
"created": "Wed, 2 Jul 2003 13:24:15 GMT",
"version": "v3"
},
{
"created": "Tue, 5 Dec 2006 21:12:13 GMT",
"version": "v4"
},
{
"created": "Fri, 8 Dec 2006 00:57:43 GMT",
"version": "v5"
}
] | 2008-11-26 | [
[
"Lichtenegger",
"Herbert I. M.",
""
],
[
"Iorio",
"Lorenzo",
""
],
[
"Mashhoon",
"Bahram",
""
]
] | The general relativistic gravitomagnetic clock effect involves a coupling between the orbital motion of a test particle and the rotation of the central mass and results in a difference in the proper periods of two counter-revolving satellites. It is shown that at O(c^-2) this effect has a simple analogue in the electromagnetic case. Moreover, in view of a possible measurement of the clock effect in the gravitational field of the Earth, we investigate the influence of some classical perturbing forces of the terrestrial space environment on the orbital motion of test bodies along opposite trajectories. |
1203.2779 | Izzet Sakalli | I.Sakalli | Effect of the cosmological constant in the Hawking radiation of 3D
charged dilaton black hole | null | Astrophys. Space Sci. 340, 317 (2012) | 10.1007/s10509-012-1053-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper deals with the semiclassical radiation spectrum of static and
circularly symmetric 3D charged dilaton black holes with cosmological constant
{\Lambda} in non-asymptotically flat spacetimes. We first review the 3D charged
dilaton black holes which are solution to low-energy string action. The wave
equation of a massless scalar field is shown to be exactly solvable in terms of
hypergeometric functions. Thus, the radiation spectrum and its corresponding
temperature are obtained, precisely. Computations at high frequency regime show
that the radiation spectrum yields the Hawking temperature of the black hole
with no charge. Unlike the chargeless case, the Hawking temperature of the
charged dilaton black holes is derived from the radiation spectrum at the low
frequencies. The utmost importance of the {\Lambda} in the latter result is
highlighted.
| [
{
"created": "Tue, 13 Mar 2012 11:50:36 GMT",
"version": "v1"
},
{
"created": "Sat, 15 Feb 2014 10:46:15 GMT",
"version": "v2"
}
] | 2014-02-18 | [
[
"Sakalli",
"I.",
""
]
] | This paper deals with the semiclassical radiation spectrum of static and circularly symmetric 3D charged dilaton black holes with cosmological constant {\Lambda} in non-asymptotically flat spacetimes. We first review the 3D charged dilaton black holes which are solution to low-energy string action. The wave equation of a massless scalar field is shown to be exactly solvable in terms of hypergeometric functions. Thus, the radiation spectrum and its corresponding temperature are obtained, precisely. Computations at high frequency regime show that the radiation spectrum yields the Hawking temperature of the black hole with no charge. Unlike the chargeless case, the Hawking temperature of the charged dilaton black holes is derived from the radiation spectrum at the low frequencies. The utmost importance of the {\Lambda} in the latter result is highlighted. |
gr-qc/0204011 | Eric Gourgoulhon | T. Damour (IHES), E. Gourgoulhon (LUTH, CNRS, Observatoire de Paris),
P. Grandclement (Northwestern University) | Circular orbits of corotating binary black holes: comparison between
analytical and numerical results | Minor revisions, accepted for publication in Phys. Rev. D, 19 pages,
6 figures | Phys.Rev. D66 (2002) 024007 | 10.1103/PhysRevD.66.024007 | null | gr-qc astro-ph | null | We compare recent numerical results, obtained within a ``helical Killing
vector'' (HKV) approach, on circular orbits of corotating binary black holes to
the analytical predictions made by the effective one body (EOB) method (which
has been recently extended to the case of spinning bodies). On the scale of the
differences between the results obtained by different numerical methods, we
find good agreement between numerical data and analytical predictions for
several invariant functions describing the dynamical properties of circular
orbits. This agreement is robust against the post-Newtonian accuracy used for
the analytical estimates, as well as under choices of resummation method for
the EOB ``effective potential'', and gets better as one uses a higher
post-Newtonian accuracy. These findings open the way to a significant
``merging'' of analytical and numerical methods, i.e. to matching an EOB-based
analytical description of the (early and late) inspiral, up to the beginning of
the plunge, to a numerical description of the plunge and merger. We illustrate
also the ``flexibility'' of the EOB approach, i.e. the possibility of
determining some ``best fit'' values for the analytical parameters by
comparison with numerical data.
| [
{
"created": "Wed, 3 Apr 2002 15:18:15 GMT",
"version": "v1"
},
{
"created": "Sat, 11 May 2002 15:21:51 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Damour",
"T.",
"",
"IHES"
],
[
"Gourgoulhon",
"E.",
"",
"LUTH, CNRS, Observatoire de Paris"
],
[
"Grandclement",
"P.",
"",
"Northwestern University"
]
] | We compare recent numerical results, obtained within a ``helical Killing vector'' (HKV) approach, on circular orbits of corotating binary black holes to the analytical predictions made by the effective one body (EOB) method (which has been recently extended to the case of spinning bodies). On the scale of the differences between the results obtained by different numerical methods, we find good agreement between numerical data and analytical predictions for several invariant functions describing the dynamical properties of circular orbits. This agreement is robust against the post-Newtonian accuracy used for the analytical estimates, as well as under choices of resummation method for the EOB ``effective potential'', and gets better as one uses a higher post-Newtonian accuracy. These findings open the way to a significant ``merging'' of analytical and numerical methods, i.e. to matching an EOB-based analytical description of the (early and late) inspiral, up to the beginning of the plunge, to a numerical description of the plunge and merger. We illustrate also the ``flexibility'' of the EOB approach, i.e. the possibility of determining some ``best fit'' values for the analytical parameters by comparison with numerical data. |
2108.09344 | Eliot Finch | Eliot Finch, Christopher J. Moore | Frequency-Domain Analysis of Black-Hole Ringdowns | 12 pages, 7 figures, plus appendix (accepted in Physical Review D on
16 November 2021) | Phys. Rev. D 104, 123034 (2021) | 10.1103/PhysRevD.104.123034 | LIGO document number P2100303-v2 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a novel, frequency-domain approach to the analysis of the
gravitational-wave ringdown signal of binary black holes and the identification
of quasinormal mode frequencies of the remnant. Our approach avoids the issues
of spectral leakage that would normally be expected (associated with the abrupt
start of the ringdown) by modeling the inspiral and merger parts of the signal
using a flexible sum of sine-Gaussian wavelets truncated at the onset of the
ringdown. Performing the analysis in the frequency domain allows us to use
standard (and by now well-established) Bayesian inference pipelines for
gravitational wave data as well as giving us the ability to readily search over
the sky position and the ringdown start time, although we find that it is
necessary to use an informative prior for the latter. We test our method by
using it to analyze several simulated signals with varying signal-to-noise
ratios injected into two- and three-detector networks. We find that our
frequency-domain approach is generally able to place tighter constraints on the
remnant black-hole mass and spin than a standard time-domain analysis.
| [
{
"created": "Fri, 20 Aug 2021 19:53:02 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Jan 2022 13:28:10 GMT",
"version": "v2"
}
] | 2022-01-11 | [
[
"Finch",
"Eliot",
""
],
[
"Moore",
"Christopher J.",
""
]
] | We propose a novel, frequency-domain approach to the analysis of the gravitational-wave ringdown signal of binary black holes and the identification of quasinormal mode frequencies of the remnant. Our approach avoids the issues of spectral leakage that would normally be expected (associated with the abrupt start of the ringdown) by modeling the inspiral and merger parts of the signal using a flexible sum of sine-Gaussian wavelets truncated at the onset of the ringdown. Performing the analysis in the frequency domain allows us to use standard (and by now well-established) Bayesian inference pipelines for gravitational wave data as well as giving us the ability to readily search over the sky position and the ringdown start time, although we find that it is necessary to use an informative prior for the latter. We test our method by using it to analyze several simulated signals with varying signal-to-noise ratios injected into two- and three-detector networks. We find that our frequency-domain approach is generally able to place tighter constraints on the remnant black-hole mass and spin than a standard time-domain analysis. |
1805.02509 | S. Sedigheh Hashemi | S. Sedigheh Hashemi and Nematollah Riazi | Boosted Kaluza- Klein magnetic monopole | 11 pages, 1 figure. arXiv admin note: text overlap with
arXiv:1405.4785 | Annals of Physics (2018) | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a Kaluza-Klein vacuum solution which is closely related to the
Gross-Perry-Sorkin (GPS) magnetic monopole. The solution can be obtained from
the Euclidean Taub-NUT solution with an extra compact fifth spatial dimension
within the formalism of Kaluza-Klein reduction. We study its physical
properties as appearing in $(3+1)$ spacetime dimensions, which turns out to be
a static magnetic monopole. We then boost the GPS magnetic monopole along the
extra dimension, and perform the Kaluza-Klein reduction. The resulting
four-dimensional spacetime is a rotating stationary system, with both electric
and magnetic fields. In fact, after the boost the magnetic monopole turns into
a string connected to a dyon.
| [
{
"created": "Fri, 4 May 2018 06:06:11 GMT",
"version": "v1"
}
] | 2018-05-08 | [
[
"Hashemi",
"S. Sedigheh",
""
],
[
"Riazi",
"Nematollah",
""
]
] | We consider a Kaluza-Klein vacuum solution which is closely related to the Gross-Perry-Sorkin (GPS) magnetic monopole. The solution can be obtained from the Euclidean Taub-NUT solution with an extra compact fifth spatial dimension within the formalism of Kaluza-Klein reduction. We study its physical properties as appearing in $(3+1)$ spacetime dimensions, which turns out to be a static magnetic monopole. We then boost the GPS magnetic monopole along the extra dimension, and perform the Kaluza-Klein reduction. The resulting four-dimensional spacetime is a rotating stationary system, with both electric and magnetic fields. In fact, after the boost the magnetic monopole turns into a string connected to a dyon. |
gr-qc/0105025 | Susana Judith Landau | Susana J. Landau, Pablo D. Sisterna and Hector Vucetich | Charge conservation and Equivalence principle | 8 pages | null | null | null | gr-qc | null | The $TH\epsilon\mu$ formalism was developed to study nonmetric theories of
gravitation. In this letter we show that theories that violate Local Lorentz
Invariance (LLI) or Local Position Invariance (LPI) also violate charge
conservation. Using upper bounds on this violation we can put very stringent
limits to violations of Einstein Equivalence Principle (EEP). These limits, in
turn, severely restrict string-based models of low energy physics.
| [
{
"created": "Mon, 7 May 2001 16:55:15 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Landau",
"Susana J.",
""
],
[
"Sisterna",
"Pablo D.",
""
],
[
"Vucetich",
"Hector",
""
]
] | The $TH\epsilon\mu$ formalism was developed to study nonmetric theories of gravitation. In this letter we show that theories that violate Local Lorentz Invariance (LLI) or Local Position Invariance (LPI) also violate charge conservation. Using upper bounds on this violation we can put very stringent limits to violations of Einstein Equivalence Principle (EEP). These limits, in turn, severely restrict string-based models of low energy physics. |
2310.02838 | Lorenzo Iorio | Lorenzo Iorio | The post-Newtonian motion around an oblate spheroid: the mixed orbital
effects due to the Newtonian oblateness and the post-Newtonian mass monopole
accelerations | LaTex2e, no Figures, no Tables, 20 pages. Version accepted for
publication in General Relativity and Gravitation | Gen. Relativ. Gravit. 55 (2023) 136 | 10.1007/s10714-023-03184-7 | null | gr-qc astro-ph.EP physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | When a test particle moves about an oblate spheroid, it is acted upon, among
other things, by two standard perturbing accelerations. One, of Newtonian
origin, is due to the quadrupole mass moment $J_2$ of the orbited body. The
other one, of the order of $\mathcal{O}\left(1/c^2\right)$, is caused by the
static, post-Newtonian field arising solely from the mass of the central
object. Both of them concur to induce \textrm{indirect}, \textrm{mixed} orbital
effects of the order of $\mathcal{O}\left(J_2/c^2\right)$. They are of the same
order of magnitude of the \textrm{direct} ones induced by the post-Newtonian
acceleration arising in presence of an oblate source, not treated here. We
calculate these less known features of motion in their full generality in terms
of the osculating Keplerian orbital elements. Subtleties pertaining the correct
calculation of their mixed net \textrm{precessions} per orbit to the full order
of $\mathcal{O}\left(J_2/c^2\right)$ are elucidated. The obtained results hold
for arbitrary orbital geometries and for any orientation of the body's spin
axis $\mathbf{\hat{k}}$ in space. The method presented is completely general,
and can be extended to any pair of post-Keplerian accelerations entering the
equations of motion of the satellite, irrespectively of their physical nature.
| [
{
"created": "Wed, 4 Oct 2023 14:06:17 GMT",
"version": "v1"
},
{
"created": "Sun, 8 Oct 2023 13:39:13 GMT",
"version": "v2"
},
{
"created": "Tue, 17 Oct 2023 14:10:08 GMT",
"version": "v3"
},
{
"created": "Sun, 19 Nov 2023 21:05:40 GMT",
"version": "v4"
}
] | 2023-12-13 | [
[
"Iorio",
"Lorenzo",
""
]
] | When a test particle moves about an oblate spheroid, it is acted upon, among other things, by two standard perturbing accelerations. One, of Newtonian origin, is due to the quadrupole mass moment $J_2$ of the orbited body. The other one, of the order of $\mathcal{O}\left(1/c^2\right)$, is caused by the static, post-Newtonian field arising solely from the mass of the central object. Both of them concur to induce \textrm{indirect}, \textrm{mixed} orbital effects of the order of $\mathcal{O}\left(J_2/c^2\right)$. They are of the same order of magnitude of the \textrm{direct} ones induced by the post-Newtonian acceleration arising in presence of an oblate source, not treated here. We calculate these less known features of motion in their full generality in terms of the osculating Keplerian orbital elements. Subtleties pertaining the correct calculation of their mixed net \textrm{precessions} per orbit to the full order of $\mathcal{O}\left(J_2/c^2\right)$ are elucidated. The obtained results hold for arbitrary orbital geometries and for any orientation of the body's spin axis $\mathbf{\hat{k}}$ in space. The method presented is completely general, and can be extended to any pair of post-Keplerian accelerations entering the equations of motion of the satellite, irrespectively of their physical nature. |
2103.04239 | Wen-Xiang Chen | Wen-Xiang Chen, Yao-Guang Zheng | The superradiant stability of Kerr-Newman black holes | arXiv admin note: substantial text overlap with arXiv:2105.05394 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, the superradiation stability of Kerr-Newman black holes is
discussed by introducing the condition used in Kerr black holes y into them.
Moreover, the motion equation of the minimal coupled scalar perturbation in a
Kerr-Newman black hole is divided into angular and radial parts. Hod
proved\cite{12} that the Kerr black hole should be superradiantly stable under
massive scalar perturbation when $\mu \ge \sqrt{2}m\Omega_H$, where $\mu$ is
the mass. In this article, a new variable y is added here to expand the results
of the above article. When $\sqrt{2(a^2+Q^2)}/{r^2_+}< \omega<
m\varOmega_H+q\varPhi_H$,particularly $\mu \ge
\sqrt{2}(m\varOmega_H+q\varPhi_H)$,so the Kerr-Newman black hole is
superradiantly stable at that time.
| [
{
"created": "Sun, 7 Mar 2021 02:54:01 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Sep 2021 11:03:35 GMT",
"version": "v2"
},
{
"created": "Tue, 19 Oct 2021 07:35:48 GMT",
"version": "v3"
},
{
"created": "Sat, 30 Oct 2021 10:23:38 GMT",
"version": "v4"
},
{
"created": "Wed, 1 Dec 2021 03:28:46 GMT",
"version": "v5"
},
{
"created": "Fri, 17 Dec 2021 11:32:40 GMT",
"version": "v6"
},
{
"created": "Sat, 23 Jul 2022 23:43:55 GMT",
"version": "v7"
}
] | 2022-07-26 | [
[
"Chen",
"Wen-Xiang",
""
],
[
"Zheng",
"Yao-Guang",
""
]
] | In this article, the superradiation stability of Kerr-Newman black holes is discussed by introducing the condition used in Kerr black holes y into them. Moreover, the motion equation of the minimal coupled scalar perturbation in a Kerr-Newman black hole is divided into angular and radial parts. Hod proved\cite{12} that the Kerr black hole should be superradiantly stable under massive scalar perturbation when $\mu \ge \sqrt{2}m\Omega_H$, where $\mu$ is the mass. In this article, a new variable y is added here to expand the results of the above article. When $\sqrt{2(a^2+Q^2)}/{r^2_+}< \omega< m\varOmega_H+q\varPhi_H$,particularly $\mu \ge \sqrt{2}(m\varOmega_H+q\varPhi_H)$,so the Kerr-Newman black hole is superradiantly stable at that time. |
2407.05002 | Vsevolod Ivanov | V. R. Ivanov and S. Yu. Vernov | Integrable Cosmological Models with an Arbitrary Number of Scalar Fields | 10 pages | null | null | null | gr-qc astro-ph.CO math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider cosmological models with an arbitrary number of scalar fields
nonminimally coupled to gravity and construct new integrable cosmological
models. In the constructed models, the Ricci scalar is an integral of motion
irrespectively of the type of metric. The general solutions of evolution
equations in the spatially flat FLRW metric have been found for models the
quartic potentials.
| [
{
"created": "Sat, 6 Jul 2024 08:40:04 GMT",
"version": "v1"
}
] | 2024-07-10 | [
[
"Ivanov",
"V. R.",
""
],
[
"Vernov",
"S. Yu.",
""
]
] | We consider cosmological models with an arbitrary number of scalar fields nonminimally coupled to gravity and construct new integrable cosmological models. In the constructed models, the Ricci scalar is an integral of motion irrespectively of the type of metric. The general solutions of evolution equations in the spatially flat FLRW metric have been found for models the quartic potentials. |
1907.08343 | Manuel Hohmann | Manuel Hohmann | Hamiltonian of new general relativity using differential forms | 4 pages, no figures; to appear in the conference proceedings of the
10th Alexander Friedmann International Seminar, International Journal of
Modern Physics A, World Scientific Publishing Company | null | 10.1142/S0217751X2040014X | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a recent work we derived the kinematic Hamiltonian and primary constraints
of the new general relativity class of teleparallel gravity theories and showed
that these theories can be grouped in 9 classes, based on the presence or
absence of primary constraints in their Hamiltonian. Here we demonstrate an
alternative approach towards this result, by using differential forms instead
of tensor components throughout the calculation. We prove that also this
alternative derivation yields the same results and show how they are related to
each other.
| [
{
"created": "Fri, 19 Jul 2019 02:06:00 GMT",
"version": "v1"
}
] | 2020-03-18 | [
[
"Hohmann",
"Manuel",
""
]
] | In a recent work we derived the kinematic Hamiltonian and primary constraints of the new general relativity class of teleparallel gravity theories and showed that these theories can be grouped in 9 classes, based on the presence or absence of primary constraints in their Hamiltonian. Here we demonstrate an alternative approach towards this result, by using differential forms instead of tensor components throughout the calculation. We prove that also this alternative derivation yields the same results and show how they are related to each other. |
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