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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0812.4712
|
Peter K.F. Kuhfittig
|
Peter K.F. Kuhfittig
|
Could some black holes have evolved from wormholes?
|
7 pages, 1 figure, updated version to incorporate recent findings
|
Schol.Res.Exch.2008:296158,2008
|
10.3814/2008/296158
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
One way to explain the present acceleration of the Universe is Einstein's
cosmological constant. It is quite likely, in view of some recent studies, that
a time-dependent equation of state had caused the Universe to evolve from an
earlier phantom-energy model. In that case traversable wormholes could have
formed spontaneously. It is shown in this paper that such wormholes would
eventually have become black holes. This would provide a possible explanation
for the huge number of black holes discovered, while any evidence for the
existence of wormholes is entirely lacking, even though wormholes are just as
good, in terms of being a prediction of general relativity, as black holes.
|
[
{
"created": "Mon, 29 Dec 2008 15:21:56 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Jan 2009 18:15:17 GMT",
"version": "v2"
},
{
"created": "Sat, 20 Nov 2010 14:43:43 GMT",
"version": "v3"
},
{
"created": "Fri, 24 Dec 2010 15:56:36 GMT",
"version": "v4"
},
{
"created": "Mon, 24 Jan 2011 15:53:09 GMT",
"version": "v5"
},
{
"created": "Sat, 30 Apr 2011 22:04:46 GMT",
"version": "v6"
}
] |
2011-05-03
|
[
[
"Kuhfittig",
"Peter K. F.",
""
]
] |
One way to explain the present acceleration of the Universe is Einstein's cosmological constant. It is quite likely, in view of some recent studies, that a time-dependent equation of state had caused the Universe to evolve from an earlier phantom-energy model. In that case traversable wormholes could have formed spontaneously. It is shown in this paper that such wormholes would eventually have become black holes. This would provide a possible explanation for the huge number of black holes discovered, while any evidence for the existence of wormholes is entirely lacking, even though wormholes are just as good, in terms of being a prediction of general relativity, as black holes.
|
2105.12413
|
Junji Jia
|
Xiaoge Xu, Tingyuan Jiang and Junji Jia
|
Deflection angle with electromagnetic interaction and
gravitational-electromagnetic dual lensing
|
16 pages, 6 figures, 1 table; to appear in JCAP
| null |
10.1088/1475-7516/2021/08/022
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The trajectory deflection and gravitational-electromagnetic dual lensing
(GEL) of charged signal in general charged static and spherically symmetric
spacetimes are considered in this work. We showed that the perturbative
approach previously developed for neutral particles can be extended to the
electromagnetic interaction case. The deflection angle still takes a
(quasi-)series form and the finite distance effect of both the source and
observer can be taken into account. Comparing to pure gravitational case, the
apparent angles of the images in the GEL, their magnifications and time delay
all receive the electromagnetic corrections starting from the first non-trivial
order. The sign and relative size of the leading corrections are determined by
$\sim \frac{Q}{M}\frac{q}{E}$ where $M,~Q,~q,~E$ are the spacetime mass and
charge, and signal particle charge and energy respectively. It is found that
for $qQ>0$ (or $<0$), the electromagnetic interaction will decrease (or
increase) the deflection angle, and in GEL the impact parameters, apparent
angles, magnifications and total travel time for each image. The time delay is
increased for small $\beta$ and $qQ>0$, and otherwise always increased
regardless the sign of $qQ$. The results are then applied to the deflection and
GEL of charged protons in cosmic rays in Reissner-Nordstrom, charged dilaton
and charged Horndeski spacetimes.
|
[
{
"created": "Wed, 26 May 2021 09:07:43 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Aug 2021 15:51:53 GMT",
"version": "v2"
}
] |
2021-08-25
|
[
[
"Xu",
"Xiaoge",
""
],
[
"Jiang",
"Tingyuan",
""
],
[
"Jia",
"Junji",
""
]
] |
The trajectory deflection and gravitational-electromagnetic dual lensing (GEL) of charged signal in general charged static and spherically symmetric spacetimes are considered in this work. We showed that the perturbative approach previously developed for neutral particles can be extended to the electromagnetic interaction case. The deflection angle still takes a (quasi-)series form and the finite distance effect of both the source and observer can be taken into account. Comparing to pure gravitational case, the apparent angles of the images in the GEL, their magnifications and time delay all receive the electromagnetic corrections starting from the first non-trivial order. The sign and relative size of the leading corrections are determined by $\sim \frac{Q}{M}\frac{q}{E}$ where $M,~Q,~q,~E$ are the spacetime mass and charge, and signal particle charge and energy respectively. It is found that for $qQ>0$ (or $<0$), the electromagnetic interaction will decrease (or increase) the deflection angle, and in GEL the impact parameters, apparent angles, magnifications and total travel time for each image. The time delay is increased for small $\beta$ and $qQ>0$, and otherwise always increased regardless the sign of $qQ$. The results are then applied to the deflection and GEL of charged protons in cosmic rays in Reissner-Nordstrom, charged dilaton and charged Horndeski spacetimes.
|
2303.15512
|
Maxime Gadioux
|
Maxime Gadioux and Harvey S. Reall
|
Creases, corners and caustics: properties of non-smooth structures on
black hole horizons
|
v2: improved discussion of crease entropy; added discussion of Bousso
bound
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The event horizon of a dynamical black hole is generically a non-smooth
hypersurface. We classify the types of non-smooth structure that can arise on a
horizon that is smooth at late time. The classification includes creases,
corners and caustic points. We prove that creases and corners form spacelike
submanifolds of dimension $2,1$ and that caustic points form a set of dimension
at most $1$. We classify "perestroikas" of these structures, in which they
undergo a qualitative change at an instant of time. A crease perestroika gives
an exact local description of the event horizon near the "instant of merger" of
a generic black hole merger. Other crease perestroikas describe horizon
nucleation or collapse of a hole in a toroidal horizon. Caustic perestroikas,
in which a pair of caustic points either nucleate or annihilate, provide a
mechanism for creases to decay. We argue that properties of quantum
entanglement entropy suggest that creases might contribute to black hole
entropy. We explain that a "Gauss-Bonnet" term in the entropy is
non-topological on a non-smooth horizon, which invalidates previous arguments
against such a term.
|
[
{
"created": "Mon, 27 Mar 2023 18:00:05 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Sep 2023 15:47:17 GMT",
"version": "v2"
}
] |
2023-09-13
|
[
[
"Gadioux",
"Maxime",
""
],
[
"Reall",
"Harvey S.",
""
]
] |
The event horizon of a dynamical black hole is generically a non-smooth hypersurface. We classify the types of non-smooth structure that can arise on a horizon that is smooth at late time. The classification includes creases, corners and caustic points. We prove that creases and corners form spacelike submanifolds of dimension $2,1$ and that caustic points form a set of dimension at most $1$. We classify "perestroikas" of these structures, in which they undergo a qualitative change at an instant of time. A crease perestroika gives an exact local description of the event horizon near the "instant of merger" of a generic black hole merger. Other crease perestroikas describe horizon nucleation or collapse of a hole in a toroidal horizon. Caustic perestroikas, in which a pair of caustic points either nucleate or annihilate, provide a mechanism for creases to decay. We argue that properties of quantum entanglement entropy suggest that creases might contribute to black hole entropy. We explain that a "Gauss-Bonnet" term in the entropy is non-topological on a non-smooth horizon, which invalidates previous arguments against such a term.
|
2104.06013
|
Yotam Sherf
|
Ram Brustein, Yotam Sherf
|
Classical Love for Quantum Blackholes
|
Replaced to agree with the published PRD version
| null |
10.1103/PhysRevD.105.024044
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present a method for comparing the classical and quantum calculations of
the electric quadrupolar Love number $k_2$ and show that our previous
derivation of the quantum Love number of a quantum blackhole matches exactly
the classical calculation of $k_2$ when quantum expectation values are replaced
by the corresponding classical quantities, as dictated by the Bohr
correspondence principle. The standard derivation of $k_2$ for classical
relativistic stars relies on fixing boundary conditions on the surface of the
star for the Einstein equations in the presence of an external perturbing
field. An alternative method for calculating $k_2$ uses properties of the
spectrum of the non-relativistic fluid modes of the star. We adopt this
alternative method and use it to derive an effective description of the
interior modes in terms of a collection of driven harmonic oscillators
characterized by different frequencies and amplitudes. We compare these two
classical methods and find that most of the interior information can be
integrated out, reducing the problem of calculating $k_2$ to fixing a single
boundary condition for the perturbed Einstein equations on the surface of the
deformed star. We then determine this single boundary condition in terms of the
spectrum of the object and proceed to identify the relationship between
classical quantities and quantum expectation values and to verify the agreement
between the results of the effective classical calculation and the quantum
calculation.
|
[
{
"created": "Tue, 13 Apr 2021 08:25:39 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Jan 2022 17:43:26 GMT",
"version": "v2"
}
] |
2022-01-20
|
[
[
"Brustein",
"Ram",
""
],
[
"Sherf",
"Yotam",
""
]
] |
We present a method for comparing the classical and quantum calculations of the electric quadrupolar Love number $k_2$ and show that our previous derivation of the quantum Love number of a quantum blackhole matches exactly the classical calculation of $k_2$ when quantum expectation values are replaced by the corresponding classical quantities, as dictated by the Bohr correspondence principle. The standard derivation of $k_2$ for classical relativistic stars relies on fixing boundary conditions on the surface of the star for the Einstein equations in the presence of an external perturbing field. An alternative method for calculating $k_2$ uses properties of the spectrum of the non-relativistic fluid modes of the star. We adopt this alternative method and use it to derive an effective description of the interior modes in terms of a collection of driven harmonic oscillators characterized by different frequencies and amplitudes. We compare these two classical methods and find that most of the interior information can be integrated out, reducing the problem of calculating $k_2$ to fixing a single boundary condition for the perturbed Einstein equations on the surface of the deformed star. We then determine this single boundary condition in terms of the spectrum of the object and proceed to identify the relationship between classical quantities and quantum expectation values and to verify the agreement between the results of the effective classical calculation and the quantum calculation.
|
1912.12626
|
Vladimir Khatsymovsky
|
V.M. Khatsymovsky
|
On the discrete version of the black hole solution
|
24 pages, typos corrected, readability improved
|
Int. Journ. Mod. Phys. A, Vol. 35, Nos. 11 & 12, 2050058 (2020)
|
10.1142/S0217751X2050058X
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A Schwarzschild type solution in Regge calculus is considered. Earlier, we
considered a mechanism of loose fixing of edge lengths due to the functional
integral measure arising from integration over connection in the functional
integral for the connection representation of the Regge action. The length
scale depends on a free dimensionless parameter that determines the final
functional measure. For this parameter and the length scale large in Planck
units, the resulting effective action is close to the Regge action.
Earlier, we considered the Regge action in terms of affine connection
matrices as functions of the metric inside the 4-simplices and found that it is
a difference form of the Hilbert-Einstein action in the leading order over
metric variations between the 4-simplices.
Now we take the (continuum) Schwarzschild problem in the form where spherical
symmetry is not set a priori and arises just in the solution, take the
difference form of the corresponding equations and get the metric (in fact, in
the Lemaitre or Painlev\'{e}-Gullstrand like frame), which is nonsingular at
the origin, just as the Newtonian gravitational potential, obeying the
difference Poisson equation with a point source, is cut off at the elementary
length and is finite at the source.
|
[
{
"created": "Sun, 29 Dec 2019 10:59:06 GMT",
"version": "v1"
},
{
"created": "Sat, 29 Aug 2020 14:42:50 GMT",
"version": "v2"
}
] |
2020-09-01
|
[
[
"Khatsymovsky",
"V. M.",
""
]
] |
A Schwarzschild type solution in Regge calculus is considered. Earlier, we considered a mechanism of loose fixing of edge lengths due to the functional integral measure arising from integration over connection in the functional integral for the connection representation of the Regge action. The length scale depends on a free dimensionless parameter that determines the final functional measure. For this parameter and the length scale large in Planck units, the resulting effective action is close to the Regge action. Earlier, we considered the Regge action in terms of affine connection matrices as functions of the metric inside the 4-simplices and found that it is a difference form of the Hilbert-Einstein action in the leading order over metric variations between the 4-simplices. Now we take the (continuum) Schwarzschild problem in the form where spherical symmetry is not set a priori and arises just in the solution, take the difference form of the corresponding equations and get the metric (in fact, in the Lemaitre or Painlev\'{e}-Gullstrand like frame), which is nonsingular at the origin, just as the Newtonian gravitational potential, obeying the difference Poisson equation with a point source, is cut off at the elementary length and is finite at the source.
|
gr-qc/9802063
|
Jorge Pullin
|
Reinaldo Gleiser, Oscar Nicasio, Richard Price and Jorge Pullin
|
The collision of boosted black holes: second order close limit
calculations
|
20 pages, RevTeX, 6 figures included with psfig
|
Phys.Rev. D59 (1999) 044024
|
10.1103/PhysRevD.59.044024
|
CGPG-98/2-1
|
gr-qc
| null |
We study the head-on collision of black holes starting from unsymmetrized,
Brill--Lindquist type data for black holes with non-vanishing initial linear
momentum. Evolution of the initial data is carried out with the ``close limit
approximation,'' in which small initial separation and momentum are assumed,
and second-order perturbation theory is used. We find agreement that is
remarkably good, and that in some ways improves with increasing momentum. This
work extends a previous study in which second order perturbation calculations
were used for momentarily stationary initial data, and another study in which
linearized perturbation theory was used for initially moving holes. In addition
to supplying answers about the collisions, the present work has revealed
several subtle points about the use of higher order perturbation theory, points
that did not arise in the previous studies. These points include issues of
normalization, and of comparison with numerical simulations, and will be
important to subsequent applications of approximation methods for collisions.
|
[
{
"created": "Thu, 26 Feb 1998 03:14:49 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Gleiser",
"Reinaldo",
""
],
[
"Nicasio",
"Oscar",
""
],
[
"Price",
"Richard",
""
],
[
"Pullin",
"Jorge",
""
]
] |
We study the head-on collision of black holes starting from unsymmetrized, Brill--Lindquist type data for black holes with non-vanishing initial linear momentum. Evolution of the initial data is carried out with the ``close limit approximation,'' in which small initial separation and momentum are assumed, and second-order perturbation theory is used. We find agreement that is remarkably good, and that in some ways improves with increasing momentum. This work extends a previous study in which second order perturbation calculations were used for momentarily stationary initial data, and another study in which linearized perturbation theory was used for initially moving holes. In addition to supplying answers about the collisions, the present work has revealed several subtle points about the use of higher order perturbation theory, points that did not arise in the previous studies. These points include issues of normalization, and of comparison with numerical simulations, and will be important to subsequent applications of approximation methods for collisions.
|
2112.04196
|
Saeed Noori Gashti
|
S. Noori Gashti, J. Sadeghi
|
Inflation, Swampland, and Landscape
|
15 pages, 3 figures, Accepted for publication in the International
Journal of Modern Physics A (IJMPA)
|
International Journal of Modern Physics A 37 (04), 2250006 (2022)
|
10.1142/S0217751X22500063
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we evaluate a new refined de Sitter (dS) conjecture
perspective. This conjecture provides interesting conditions in studying
various inflationary models. Therefore we challenge refined dS conjecture with
a general method for analyzing the potentials with the inflectional point near
the top (V''= 0). We find the compatible spaces for our inflationary model that
live out of swampland according to the latest observational data, such as
Planck 2018.
|
[
{
"created": "Wed, 8 Dec 2021 09:49:38 GMT",
"version": "v1"
}
] |
2023-02-14
|
[
[
"Gashti",
"S. Noori",
""
],
[
"Sadeghi",
"J.",
""
]
] |
In this paper, we evaluate a new refined de Sitter (dS) conjecture perspective. This conjecture provides interesting conditions in studying various inflationary models. Therefore we challenge refined dS conjecture with a general method for analyzing the potentials with the inflectional point near the top (V''= 0). We find the compatible spaces for our inflationary model that live out of swampland according to the latest observational data, such as Planck 2018.
|
1308.4704
|
Richard O'Shaughnessy
|
R. O'Shaughnessy (1), B. Farr (2), E. Ochsner (1), Hee-Suk Cho (3), C.
Kim (4), Chang-Hwan Lee (3) ((1) University of Wisconsin-Milwaukee, (2)
Northwestern University, (3) Department of Physics, Pusan National
University, Korea, (4) Department of Physics, West Virginia University)
|
Parameter Estimation of Gravitational Waves from Nonprecessing BH-NS
Inspirals with higher harmonics: Comparing MCMC posteriors to an Effective
Fisher Matrix
|
v2: Corrected figures, plus improvements in response to referee
|
Phys. Rev. D 89, 064048 (2014)
|
10.1103/PhysRevD.89.064048
|
LIGO DCC P1300110
|
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Using the \texttt{lalinference} Markov-chain Monte Carlo parameter estimation
code, we examine two distinct nonprecessing black hole-neutron star (BH-NS)
binaries with and without higher-order harmonics. Our simulations suggest that
higher harmonics provide a minimal amount of additional information,
principally about source geometry. Higher harmonics do provide
disproportionately more information than expected from the signal power. Our
results compare favorably to the "effective Fisher matrix" approach.
Extrapolating using analytic scalings, we expect higher harmonics will provide
little new information about nonprecessing BH-NS binaries at the signal
amplitudes expected for the first few detections. Any study of subdominant
degrees of freedom in gravitational wave astronomy can adopt the tools
presented here ($V/V_{\rm prior}$ and $D_{KL}$) to assess whether new physics
is accessible (e.g., modifications of gravity; spin-orbit misalignment) and if
so precisely what information those new parameters provide. For
astrophysicists, we provide a concrete illustration of how well parameters of a
BH-NS binary can be measured, relevant to the astrophysical interpretation of
coincident EM and GW events (e.g., short GRBs). For our fiducial
initial-detector example, the individual masses can be determined to lie
between $7.11-11.48 M_\odot$ and $1.77-1.276M_\odot$ at greater than 99%
confidence, accounting for unknown BH spin. Assuming comparable control over
waveform systematics, future measurements of BH-NS binaries can constrain the
BH and perhaps NS mass distributions.
|
[
{
"created": "Wed, 21 Aug 2013 20:29:42 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Feb 2014 18:04:10 GMT",
"version": "v2"
}
] |
2014-03-26
|
[
[
"O'Shaughnessy",
"R.",
""
],
[
"Farr",
"B.",
""
],
[
"Ochsner",
"E.",
""
],
[
"Cho",
"Hee-Suk",
""
],
[
"Kim",
"C.",
""
],
[
"Lee",
"Chang-Hwan",
""
]
] |
Using the \texttt{lalinference} Markov-chain Monte Carlo parameter estimation code, we examine two distinct nonprecessing black hole-neutron star (BH-NS) binaries with and without higher-order harmonics. Our simulations suggest that higher harmonics provide a minimal amount of additional information, principally about source geometry. Higher harmonics do provide disproportionately more information than expected from the signal power. Our results compare favorably to the "effective Fisher matrix" approach. Extrapolating using analytic scalings, we expect higher harmonics will provide little new information about nonprecessing BH-NS binaries at the signal amplitudes expected for the first few detections. Any study of subdominant degrees of freedom in gravitational wave astronomy can adopt the tools presented here ($V/V_{\rm prior}$ and $D_{KL}$) to assess whether new physics is accessible (e.g., modifications of gravity; spin-orbit misalignment) and if so precisely what information those new parameters provide. For astrophysicists, we provide a concrete illustration of how well parameters of a BH-NS binary can be measured, relevant to the astrophysical interpretation of coincident EM and GW events (e.g., short GRBs). For our fiducial initial-detector example, the individual masses can be determined to lie between $7.11-11.48 M_\odot$ and $1.77-1.276M_\odot$ at greater than 99% confidence, accounting for unknown BH spin. Assuming comparable control over waveform systematics, future measurements of BH-NS binaries can constrain the BH and perhaps NS mass distributions.
|
1608.00113
|
Tiberiu Harko
|
Min-Xing Xu, Tiberiu Harko, Shi-Dong Liang
|
Quantum Cosmology of $f(R,T)$ gravity
|
20 pages, no figures, accepted for publication in EPJC
|
The European Physical Journal C, 76(8), 1-19 (2016)
|
10.1140/epjc/s10052-016-4303-6
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Modified gravity theories have the potential of explaining the recent
acceleration of the Universe without resorting to the mysterious concept of
dark energy. In particular, it has been pointed out that matter-geometry
coupling may be responsible for the recent cosmological dynamics of the
Universe, and matter itself may play a more fundamental role in the description
of the gravitational processes that usually assumed. We study the quantum
cosmology of the $f(R,T)$ gravity theory, in which the effective Lagrangian of
the gravitational field is given by an arbitrary function of the Ricci scalar,
and the trace of the matter energy-momentum tensor, respectively. For the
background geometry we adopt the Friedmann--Robertson--Walker metric, and we
assume that matter content of the Universe consists of a perfect fluid. We
obtain the general form of the gravitational Hamiltonian, of the quantum
potential, and of the canonical momenta, respectively. This allows us to
formulate the full Wheeler-de Witt equation describing the quantum properties
of this modified gravity model. As a specific application we consider in detail
the quantum cosmology of the $f(R,T)=F^0(R)+\theta RT$ model, in which $F^0(R)$
is an arbitrary function of the Ricci scalar, and $\theta $ is a function of
the scale factor only. The Hamiltonian form of the equations of motion, and the
Wheeler-de Witt equations are obtained, and a time parameter for the
corresponding dynamical system is identified, which allows to formulate the
Schr\"{o}dinger--Wheeler--de Witt equation for the quantum-mechanical
description of the model under consideration. A perturbative approach for the
study of this equation is developed, and the energy levels of the Universe are
obtained by using a twofold degenerate perturbation approach. A second
quantization approach for the description of quantum time is also proposed, and
briefly discussed.
|
[
{
"created": "Sat, 30 Jul 2016 12:42:14 GMT",
"version": "v1"
}
] |
2016-08-17
|
[
[
"Xu",
"Min-Xing",
""
],
[
"Harko",
"Tiberiu",
""
],
[
"Liang",
"Shi-Dong",
""
]
] |
Modified gravity theories have the potential of explaining the recent acceleration of the Universe without resorting to the mysterious concept of dark energy. In particular, it has been pointed out that matter-geometry coupling may be responsible for the recent cosmological dynamics of the Universe, and matter itself may play a more fundamental role in the description of the gravitational processes that usually assumed. We study the quantum cosmology of the $f(R,T)$ gravity theory, in which the effective Lagrangian of the gravitational field is given by an arbitrary function of the Ricci scalar, and the trace of the matter energy-momentum tensor, respectively. For the background geometry we adopt the Friedmann--Robertson--Walker metric, and we assume that matter content of the Universe consists of a perfect fluid. We obtain the general form of the gravitational Hamiltonian, of the quantum potential, and of the canonical momenta, respectively. This allows us to formulate the full Wheeler-de Witt equation describing the quantum properties of this modified gravity model. As a specific application we consider in detail the quantum cosmology of the $f(R,T)=F^0(R)+\theta RT$ model, in which $F^0(R)$ is an arbitrary function of the Ricci scalar, and $\theta $ is a function of the scale factor only. The Hamiltonian form of the equations of motion, and the Wheeler-de Witt equations are obtained, and a time parameter for the corresponding dynamical system is identified, which allows to formulate the Schr\"{o}dinger--Wheeler--de Witt equation for the quantum-mechanical description of the model under consideration. A perturbative approach for the study of this equation is developed, and the energy levels of the Universe are obtained by using a twofold degenerate perturbation approach. A second quantization approach for the description of quantum time is also proposed, and briefly discussed.
|
gr-qc/0108060
|
Hajime Sotani
|
Hajime Sotani, Kazuhiro Tominaga, and Kei-ichi Maeda
|
Density Discontinuity of a Neutron Star and Gravitational Waves
|
REVTeX,18 pages, 8 figures
|
Phys.Rev. D65 (2002) 024010
|
10.1103/PhysRevD.65.024010
|
WU-AP/135/01
|
gr-qc
| null |
We calculate quasi-normal f- and g-modes of a neutron star with density
discontinuity, which may appear in a phase transition at extreme high density.
We find that discontinuity will reflect largely on the f-mode, and that the
g-mode could also be important for a less massive star.
|
[
{
"created": "Fri, 24 Aug 2001 11:51:07 GMT",
"version": "v1"
}
] |
2009-11-07
|
[
[
"Sotani",
"Hajime",
""
],
[
"Tominaga",
"Kazuhiro",
""
],
[
"Maeda",
"Kei-ichi",
""
]
] |
We calculate quasi-normal f- and g-modes of a neutron star with density discontinuity, which may appear in a phase transition at extreme high density. We find that discontinuity will reflect largely on the f-mode, and that the g-mode could also be important for a less massive star.
|
gr-qc/0210076
| null |
Sergei M. Kopeikin (University of Missouri-Columbia, USA)
|
Retardation of Gravity in Binary Pulsars
|
4 pages, no figures, to appear in the proceedings of the "Radio
Pulsars" meeting, Crete, Greece, August 26-29, 2002; eds. M. Bailes, D. Nice
and S. Thorsett
|
Radio Pulsars. Eds. M. Bailes, D. Nice and S. Thorsett. ASP
Conference Series, Vol. 302 (Sheridan Books 2003) pp. 111 - 114
| null | null |
gr-qc astro-ph
| null |
We study the effect of retardation of gravity in binary pulsars. It appears
in pulsar timing formula as a periodic excess time delay to the Shapiro effect.
The retardation of gravity effect can be large enough for observation in binary
pulsars with the nearly edgewise orbits and relatively large ratio of the
projected semimajor axis to the orbital period of the pulsar. If one succeeds
in measuring the retardation of gravity it will give further experimental
evidence in favor of General Relativity.
|
[
{
"created": "Wed, 23 Oct 2002 00:01:57 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Kopeikin",
"Sergei M.",
"",
"University of Missouri-Columbia, USA"
]
] |
We study the effect of retardation of gravity in binary pulsars. It appears in pulsar timing formula as a periodic excess time delay to the Shapiro effect. The retardation of gravity effect can be large enough for observation in binary pulsars with the nearly edgewise orbits and relatively large ratio of the projected semimajor axis to the orbital period of the pulsar. If one succeeds in measuring the retardation of gravity it will give further experimental evidence in favor of General Relativity.
|
2004.06525
|
Dipanjan Dey
|
Ashok B. Joshi, Dipanjan Dey, Pankaj S. Joshi, Parth Bambhaniya
|
Shadow of a Naked Singularity without Photon Sphere
|
9 pages, 12 figures
|
Phys. Rev. D 102, 024022 (2020)
|
10.1103/PhysRevD.102.024022
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
It is generally believed that the shadows of either a black hole or naked
singularity arise due to photon spheres developing in these spacetimes. Here we
propose a new spherically symmetric naked singularity spacetime solution of
Einstein equations which has no photon sphere, and we show that the singularity
casts a shadow in the absence of the photon sphere. We discuss some novel
features of this shadow and the lightlike geodesics in this spacetime. We
compare the shadow of the naked singularity here with shadows cast by
Schwarzschild black hole and the first type of Joshi-Malafarina-Narayan (JMN1)
naked singularity, where for the last two spacetimes the shadow is formed due
to the presence of a photon sphere. It is seen, in particular, that the size of
shadow of the singularity is considerably smaller than that of a black hole.
Our analysis shows that the shadow of this naked singularity is distinguishable
from the shadow of a Schwarzschild black hole and the JMN1 naked singularity.
These results are useful and important in the context of recent observations of
shadow of the M87 galactic center.
|
[
{
"created": "Tue, 14 Apr 2020 14:06:51 GMT",
"version": "v1"
}
] |
2020-07-15
|
[
[
"Joshi",
"Ashok B.",
""
],
[
"Dey",
"Dipanjan",
""
],
[
"Joshi",
"Pankaj S.",
""
],
[
"Bambhaniya",
"Parth",
""
]
] |
It is generally believed that the shadows of either a black hole or naked singularity arise due to photon spheres developing in these spacetimes. Here we propose a new spherically symmetric naked singularity spacetime solution of Einstein equations which has no photon sphere, and we show that the singularity casts a shadow in the absence of the photon sphere. We discuss some novel features of this shadow and the lightlike geodesics in this spacetime. We compare the shadow of the naked singularity here with shadows cast by Schwarzschild black hole and the first type of Joshi-Malafarina-Narayan (JMN1) naked singularity, where for the last two spacetimes the shadow is formed due to the presence of a photon sphere. It is seen, in particular, that the size of shadow of the singularity is considerably smaller than that of a black hole. Our analysis shows that the shadow of this naked singularity is distinguishable from the shadow of a Schwarzschild black hole and the JMN1 naked singularity. These results are useful and important in the context of recent observations of shadow of the M87 galactic center.
|
1108.4256
|
Grigory Vereshkov
|
Grigory Vereshkov and Leonid Marochnik
|
Quantum gravity in Heisenberg representation and self-consistent theory
of gravitons in macroscopic spacetime
|
15 pages; v2: Expanded explanation of the reasons why the vast
majority of papers on the quantum theory of gravitons published in 1977-2008
is erroneous
|
J. Mod. Phys. 4, 285-297 (2013)
|
10.4236/jmp.2013.42039
| null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The first mathematically consistent exact equations of quantum gravity in the
Heisenberg representation and Hamilton gauge are obtained. It is shown that the
path integral over the canonical variables in the Hamilton gauge is
mathematically equivalent to the operator equations of quantum theory of
gravity with canonical rules of quantization of the gravitational and ghost
fields. In its operator formulation, the theory can be used to calculate the
graviton S-matrix as well as to describe the quantum evolution of macroscopic
system of gravitons in the non-stationary Universe or in the vicinity of
relativistic objects. In the S-matrix case, the standard results are obtained.
For problems of the second type, the original Heisenberg equations of quantum
gravity are converted to a self-consistent system of equations for the metric
of the macroscopic spacetime and Heisenberg operators of quantum fields. It is
shown that conditions of the compatibility and internal consistency of this
system of equations are performed without restrictions on the amplitude and
wavelength of gravitons and ghosts. The status of ghost fields in the various
formulations of quantum theory of gravity is discussed.
|
[
{
"created": "Mon, 22 Aug 2011 08:24:40 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Mar 2013 09:53:46 GMT",
"version": "v2"
}
] |
2013-03-06
|
[
[
"Vereshkov",
"Grigory",
""
],
[
"Marochnik",
"Leonid",
""
]
] |
The first mathematically consistent exact equations of quantum gravity in the Heisenberg representation and Hamilton gauge are obtained. It is shown that the path integral over the canonical variables in the Hamilton gauge is mathematically equivalent to the operator equations of quantum theory of gravity with canonical rules of quantization of the gravitational and ghost fields. In its operator formulation, the theory can be used to calculate the graviton S-matrix as well as to describe the quantum evolution of macroscopic system of gravitons in the non-stationary Universe or in the vicinity of relativistic objects. In the S-matrix case, the standard results are obtained. For problems of the second type, the original Heisenberg equations of quantum gravity are converted to a self-consistent system of equations for the metric of the macroscopic spacetime and Heisenberg operators of quantum fields. It is shown that conditions of the compatibility and internal consistency of this system of equations are performed without restrictions on the amplitude and wavelength of gravitons and ghosts. The status of ghost fields in the various formulations of quantum theory of gravity is discussed.
|
1005.4530
|
Richard Woodard
|
L.H. Ford (Tufts University), S.P. Miao (CECS), Kin-Wang Ng (Academia
Sinica), R.P. Woodard (U. of Florida) and Chun-Hsien Wu (Academia Sinica)
|
Quantum Stress Tensor Fluctuations of a Conformal Field and Inflationary
Cosmology
|
31 pages, 1 figure, uses LaTeX2epsilon
|
Phys.Rev.D82:043501,2010
|
10.1103/PhysRevD.82.043501
|
CECS-PHY-10/6, UFIFT-QG-10-02
|
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We discuss the additional perturbation introduced during inflation by quantum
stress tensor fluctuations of a conformally invariant field such as the photon.
We consider both a kinematical model, which deals only with the expansion
fluctuations of geodesics, and a dynamical model which treats the coupling of
the stress tensor fluctuations to a scalar inflaton. In neither model do we
find any growth at late times, in accordance with a theorem due to Weinberg.
What we find instead is a correction which becomes larger the earlier one
starts inflation. This correction is non-Gaussian and highly scale dependent,
so the absence of such effects from the observed power spectra may imply a
constraint on the total duration of inflation. We discuss different views about
the validity of perturbation theory at very early times during which currently
observable modes are transplanckian.
|
[
{
"created": "Tue, 25 May 2010 10:56:00 GMT",
"version": "v1"
}
] |
2011-08-15
|
[
[
"Ford",
"L. H.",
"",
"Tufts University"
],
[
"Miao",
"S. P.",
"",
"CECS"
],
[
"Ng",
"Kin-Wang",
"",
"Academia\n Sinica"
],
[
"Woodard",
"R. P.",
"",
"U. of Florida"
],
[
"Wu",
"Chun-Hsien",
"",
"Academia Sinica"
]
] |
We discuss the additional perturbation introduced during inflation by quantum stress tensor fluctuations of a conformally invariant field such as the photon. We consider both a kinematical model, which deals only with the expansion fluctuations of geodesics, and a dynamical model which treats the coupling of the stress tensor fluctuations to a scalar inflaton. In neither model do we find any growth at late times, in accordance with a theorem due to Weinberg. What we find instead is a correction which becomes larger the earlier one starts inflation. This correction is non-Gaussian and highly scale dependent, so the absence of such effects from the observed power spectra may imply a constraint on the total duration of inflation. We discuss different views about the validity of perturbation theory at very early times during which currently observable modes are transplanckian.
|
1503.03436
|
Katy Clough Ms
|
Katy Clough, Pau Figueras, Hal Finkel, Markus Kunesch, Eugene A. Lim,
Saran Tunyasuvunakool
|
GRChombo : Numerical Relativity with Adaptive Mesh Refinement
|
48 pages, 24 figures
|
Class.Quant.Grav. 32 (2015) 24, 245011
|
10.1088/0264-9381/32/24/245011
|
KCL-PH-TH/2015-40
|
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, we introduce GRChombo: a new numerical relativity code which
incorporates full adaptive mesh refinement (AMR) using block structured
Berger-Rigoutsos grid generation. The code supports non-trivial
"many-boxes-in-many-boxes" mesh hierarchies and massive parallelism through the
Message Passing Interface (MPI). GRChombo evolves the Einstein equation using
the standard BSSN formalism, with an option to turn on CCZ4 constraint damping
if required. The AMR capability permits the study of a range of new physics
which has previously been computationally infeasible in a full 3+1 setting,
whilst also significantly simplifying the process of setting up the mesh for
these problems. We show that GRChombo can stably and accurately evolve standard
spacetimes such as binary black hole mergers and scalar collapses into black
holes, demonstrate the performance characteristics of our code, and discuss
various physics problems which stand to benefit from the AMR technique.
|
[
{
"created": "Wed, 11 Mar 2015 18:20:21 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Sep 2015 18:20:40 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Feb 2016 16:07:30 GMT",
"version": "v3"
}
] |
2016-02-09
|
[
[
"Clough",
"Katy",
""
],
[
"Figueras",
"Pau",
""
],
[
"Finkel",
"Hal",
""
],
[
"Kunesch",
"Markus",
""
],
[
"Lim",
"Eugene A.",
""
],
[
"Tunyasuvunakool",
"Saran",
""
]
] |
In this work, we introduce GRChombo: a new numerical relativity code which incorporates full adaptive mesh refinement (AMR) using block structured Berger-Rigoutsos grid generation. The code supports non-trivial "many-boxes-in-many-boxes" mesh hierarchies and massive parallelism through the Message Passing Interface (MPI). GRChombo evolves the Einstein equation using the standard BSSN formalism, with an option to turn on CCZ4 constraint damping if required. The AMR capability permits the study of a range of new physics which has previously been computationally infeasible in a full 3+1 setting, whilst also significantly simplifying the process of setting up the mesh for these problems. We show that GRChombo can stably and accurately evolve standard spacetimes such as binary black hole mergers and scalar collapses into black holes, demonstrate the performance characteristics of our code, and discuss various physics problems which stand to benefit from the AMR technique.
|
2304.02035
|
James Alvey
|
Uddipta Bhardwaj, James Alvey, Benjamin Kurt Miller, Samaya Nissanke,
Christoph Weniger
|
Peregrine: Sequential simulation-based inference for gravitational wave
signals
|
14 pages, 5 figures. Code: peregrine available at
https://github.com/peregrine-gw/peregrine. Matches published version
| null | null | null |
gr-qc astro-ph.CO astro-ph.HE astro-ph.IM
|
http://creativecommons.org/licenses/by/4.0/
|
The current and upcoming generations of gravitational wave experiments
represent an exciting step forward in terms of detector sensitivity and
performance. For example, key upgrades at the LIGO, Virgo and KAGRA facilities
will see the next observing run (O4) probe a spatial volume around four times
larger than the previous run (O3), and design implementations for e.g. the
Einstein Telescope, Cosmic Explorer and LISA experiments are taking shape to
explore a wider frequency range and probe cosmic distances. In this context,
however, a number of very real data analysis problems face the gravitational
wave community. For example, it will be crucial to develop tools and strategies
to analyse (amongst other scenarios) signals that arrive coincidentally in
detectors, longer signals that are in the presence of non-stationary noise or
other shorter transients, as well as noisy, potentially correlated, coherent
stochastic backgrounds. With these challenges in mind, we develop peregrine, a
new sequential simulation-based inference approach designed to study broad
classes of gravitational wave signal. In this work, we describe the method and
implementation, before demonstrating its accuracy and robustness through direct
comparison with established likelihood-based methods. Specifically, we show
that we are able to fully reconstruct the posterior distributions for every
parameter of a spinning, precessing compact binary coalescence using one of the
most physically detailed and computationally expensive waveform approximants
(SEOBNRv4PHM). Crucially, we are able to do this using only 2% of the waveform
evaluations that are required in e.g. nested sampling approaches. Finally, we
provide some outlook as to how this level of simulation efficiency and
flexibility in the statistical analysis could allow peregrine to tackle these
current and future gravitational wave data analysis problems.
|
[
{
"created": "Tue, 4 Apr 2023 18:00:01 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Jul 2024 07:21:09 GMT",
"version": "v2"
}
] |
2024-07-03
|
[
[
"Bhardwaj",
"Uddipta",
""
],
[
"Alvey",
"James",
""
],
[
"Miller",
"Benjamin Kurt",
""
],
[
"Nissanke",
"Samaya",
""
],
[
"Weniger",
"Christoph",
""
]
] |
The current and upcoming generations of gravitational wave experiments represent an exciting step forward in terms of detector sensitivity and performance. For example, key upgrades at the LIGO, Virgo and KAGRA facilities will see the next observing run (O4) probe a spatial volume around four times larger than the previous run (O3), and design implementations for e.g. the Einstein Telescope, Cosmic Explorer and LISA experiments are taking shape to explore a wider frequency range and probe cosmic distances. In this context, however, a number of very real data analysis problems face the gravitational wave community. For example, it will be crucial to develop tools and strategies to analyse (amongst other scenarios) signals that arrive coincidentally in detectors, longer signals that are in the presence of non-stationary noise or other shorter transients, as well as noisy, potentially correlated, coherent stochastic backgrounds. With these challenges in mind, we develop peregrine, a new sequential simulation-based inference approach designed to study broad classes of gravitational wave signal. In this work, we describe the method and implementation, before demonstrating its accuracy and robustness through direct comparison with established likelihood-based methods. Specifically, we show that we are able to fully reconstruct the posterior distributions for every parameter of a spinning, precessing compact binary coalescence using one of the most physically detailed and computationally expensive waveform approximants (SEOBNRv4PHM). Crucially, we are able to do this using only 2% of the waveform evaluations that are required in e.g. nested sampling approaches. Finally, we provide some outlook as to how this level of simulation efficiency and flexibility in the statistical analysis could allow peregrine to tackle these current and future gravitational wave data analysis problems.
|
1305.3757
|
Bin Chen
|
Bin Chen and Jia-ju Zhang
|
Thermodynamics in Black-hole/CFT Correspondence
|
8 pages. Essay awarded honourable mention in the Gravity Research
Foundation 2013 Awards for Essays on Gravitation
|
Int. J. Mod. Phys. D22 (2013) 1342012
|
10.1142/S0218271813420121
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The area law of Bekenstein-Hawking entropy of the black hole suggests that
the black hole should have a lower-dimensional holographic description. It has
been found recently that a large class of rotating and charged black holes
could be holographically described a two-dimensional (2D) conformal field
theory (CFT). We show that the universal information of the dual CFT, including
the central charges and the temperatures, is fully encoded in the
thermodynamics laws of both outer and inner horizons. These laws,
characterizing how the black hole responds under the perturbation, allows us to
read different dual pictures with respect to different kinds of perturbations.
The remarkable effectiveness of this thermodynamics method suggest that the
inner horizon could play a key role in the study of holographic description of
the black hole.
|
[
{
"created": "Thu, 16 May 2013 10:59:14 GMT",
"version": "v1"
}
] |
2015-04-29
|
[
[
"Chen",
"Bin",
""
],
[
"Zhang",
"Jia-ju",
""
]
] |
The area law of Bekenstein-Hawking entropy of the black hole suggests that the black hole should have a lower-dimensional holographic description. It has been found recently that a large class of rotating and charged black holes could be holographically described a two-dimensional (2D) conformal field theory (CFT). We show that the universal information of the dual CFT, including the central charges and the temperatures, is fully encoded in the thermodynamics laws of both outer and inner horizons. These laws, characterizing how the black hole responds under the perturbation, allows us to read different dual pictures with respect to different kinds of perturbations. The remarkable effectiveness of this thermodynamics method suggest that the inner horizon could play a key role in the study of holographic description of the black hole.
|
1210.6127
|
Wei Chieh Liang
|
Wei Chieh Liang and Si Chen Lee
|
Vorticity, Gyroscopic precession, and Spin-Curvature Force
| null |
Phys. Rev. D 87, 044024 (2013)
| null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In investigating the relation between vorticity and gyroscopic precession, we
calculate the vorticity vector in Godel, Kerr, Lewis, Schwarzschild, Minkowski
metric and find out the vorticity vector of the specific observers is the
angular velocity of gyroscopic precession. Furthermore, considering space-time
torsion will flip the vorticity and spin-curvature force to opposite sign. This
result is very similar to the behavior of positive and negative helicity of
quantum spin in Stern-Gerlach force. It implies that the inclusion of torsion
will lead to analogous property of quantum spin even in classical treatment.
|
[
{
"created": "Tue, 23 Oct 2012 04:56:31 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Feb 2013 08:12:40 GMT",
"version": "v2"
},
{
"created": "Wed, 6 Feb 2013 07:39:58 GMT",
"version": "v3"
},
{
"created": "Mon, 11 Feb 2013 18:12:16 GMT",
"version": "v4"
}
] |
2013-02-12
|
[
[
"Liang",
"Wei Chieh",
""
],
[
"Lee",
"Si Chen",
""
]
] |
In investigating the relation between vorticity and gyroscopic precession, we calculate the vorticity vector in Godel, Kerr, Lewis, Schwarzschild, Minkowski metric and find out the vorticity vector of the specific observers is the angular velocity of gyroscopic precession. Furthermore, considering space-time torsion will flip the vorticity and spin-curvature force to opposite sign. This result is very similar to the behavior of positive and negative helicity of quantum spin in Stern-Gerlach force. It implies that the inclusion of torsion will lead to analogous property of quantum spin even in classical treatment.
|
0906.3547
|
R Loll
|
T.G. Budd, R. Loll
|
In Search of Fundamental Discreteness in 2+1 Dimensional Quantum Gravity
|
29 pages, 18 figures
|
Class.Quant.Grav.26:185011,2009
|
10.1088/0264-9381/26/18/185011
|
ITP-UU-09/24
|
gr-qc hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Inspired by previous work in 2+1 dimensional quantum gravity, which found
evidence for a discretization of time in the quantum theory, we reexamine the
issue for the case of pure Lorentzian gravity with vanishing cosmological
constant and spatially compact universes of genus larger than 1. Taking as our
starting point the Chern-Simons formulation with Poincare gauge group, we
identify a set of length variables corresponding to space- and timelike
distances along geodesics in three-dimensional Minkowski space. These are Dirac
observables, that is, functions on the reduced phase space, whose quantization
is essentially unique. For both space- and timelike distance operators, the
spectrum is continuous and not bounded away from zero.
|
[
{
"created": "Thu, 18 Jun 2009 23:13:54 GMT",
"version": "v1"
}
] |
2009-09-28
|
[
[
"Budd",
"T. G.",
""
],
[
"Loll",
"R.",
""
]
] |
Inspired by previous work in 2+1 dimensional quantum gravity, which found evidence for a discretization of time in the quantum theory, we reexamine the issue for the case of pure Lorentzian gravity with vanishing cosmological constant and spatially compact universes of genus larger than 1. Taking as our starting point the Chern-Simons formulation with Poincare gauge group, we identify a set of length variables corresponding to space- and timelike distances along geodesics in three-dimensional Minkowski space. These are Dirac observables, that is, functions on the reduced phase space, whose quantization is essentially unique. For both space- and timelike distance operators, the spectrum is continuous and not bounded away from zero.
|
1610.05260
|
Breno Giacchini
|
Antonio Accioly, Breno L. Giacchini, Ilya L. Shapiro
|
Low-energy effects in a higher-derivative gravity model with real and
complex massive poles
|
43 pages. Matches the version published in PRD
|
Phys. Rev. D 96, 104004 (2017)
|
10.1103/PhysRevD.96.104004
| null |
gr-qc hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The most simple superrenormalizable model of quantum gravity is based on the
general local covariant six-derivative action. In addition to graviton such a
theory has massive scalar and tensor modes. It was shown recently that in the
case when the massive poles emerge in complex conjugate pairs, the theory has
also unitary $S$-matrix and hence can be seen as a candidate to be a consistent
quantum gravity theory. In the present work we construct the modified Newton
potential and explore the gravitational light bending in a general
six-derivative theory, including the most interesting case of complex massive
poles. In the case of the light deflection the results are obtained within
classical and semiclassical approaches.
|
[
{
"created": "Mon, 17 Oct 2016 18:48:09 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Nov 2016 04:10:23 GMT",
"version": "v2"
},
{
"created": "Mon, 31 Jul 2017 04:29:40 GMT",
"version": "v3"
},
{
"created": "Thu, 9 Nov 2017 17:41:26 GMT",
"version": "v4"
}
] |
2017-11-10
|
[
[
"Accioly",
"Antonio",
""
],
[
"Giacchini",
"Breno L.",
""
],
[
"Shapiro",
"Ilya L.",
""
]
] |
The most simple superrenormalizable model of quantum gravity is based on the general local covariant six-derivative action. In addition to graviton such a theory has massive scalar and tensor modes. It was shown recently that in the case when the massive poles emerge in complex conjugate pairs, the theory has also unitary $S$-matrix and hence can be seen as a candidate to be a consistent quantum gravity theory. In the present work we construct the modified Newton potential and explore the gravitational light bending in a general six-derivative theory, including the most interesting case of complex massive poles. In the case of the light deflection the results are obtained within classical and semiclassical approaches.
|
gr-qc/0505106
|
Lorenzo Iorio
|
Lorenzo Iorio
|
The impact of the new Earth gravity model EIGEN-CG03C on the measurement
of the Lense-Thirring effect with some existing Earth satellites
|
LaTex2e, 7 pages, 16 references, 1 table. It is an update of the
impact of the even zonal harmonics of the geopotential on the Lense-Thirring
effect with the EIGEN-GGM03C Earth gravity model publicly released on May 11
2005. Typos corrected. Reference added. To appear in General Relativity and
Gravitation, March 2006
|
Gen.Rel.Grav. 38 (2006) 523-527
|
10.1007/s10714-006-0239-8
| null |
gr-qc astro-ph physics.geo-ph
| null |
The impact of the latest combined CHAMP/GRACE/terrestrial measurements Earth
gravity model EIGEN-CG03C on the measurement of the Lense-Thirring effect with
some linear combinations of the nodes of some of the existing Earth's
artificial satellites is presented. The 1-sigma upper bound of the systematic
error in the node-node LAGEOS-LAGEOS II combination is 3.9% (4% with
EIGEN-GRACE02S, \sim 6% with EIGEN-CG01C and \sim 9% with GGM02S), while it is
1$% for the node-only LAGEOS-LAGEOS II-Ajisai-Jason-1 combination (2% with
EIGEN-GRACE02S, 1.6% with EIGEN-CG01C and 2.7% with GGM02S).
|
[
{
"created": "Fri, 20 May 2005 10:27:54 GMT",
"version": "v1"
},
{
"created": "Wed, 25 May 2005 14:11:04 GMT",
"version": "v2"
},
{
"created": "Sun, 2 Oct 2005 10:17:25 GMT",
"version": "v3"
}
] |
2016-08-31
|
[
[
"Iorio",
"Lorenzo",
""
]
] |
The impact of the latest combined CHAMP/GRACE/terrestrial measurements Earth gravity model EIGEN-CG03C on the measurement of the Lense-Thirring effect with some linear combinations of the nodes of some of the existing Earth's artificial satellites is presented. The 1-sigma upper bound of the systematic error in the node-node LAGEOS-LAGEOS II combination is 3.9% (4% with EIGEN-GRACE02S, \sim 6% with EIGEN-CG01C and \sim 9% with GGM02S), while it is 1$% for the node-only LAGEOS-LAGEOS II-Ajisai-Jason-1 combination (2% with EIGEN-GRACE02S, 1.6% with EIGEN-CG01C and 2.7% with GGM02S).
|
1005.1809
|
Julien Larena
|
Jean-Philippe Uzan, George F.R. Ellis and Julien Larena
|
A two-mass expanding exact space-time solution
|
15 pages, 5 figures. Replaced to match the published version
|
Gen.Rel.Grav.43:191-205,2011
|
10.1007/s10714-010-1081-6
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In order to understand how locally static configurations around
gravitationally bound bodies can be embedded in an expanding universe, we
investigate the solutions of general relativity describing a space-time whose
spatial sections have the topology of a 3-sphere with two identical masses at
the poles. We show that Israel junction conditions imply that two spherically
symmetric static regions around the masses cannot be glued together. If one is
interested in an exterior solution, this prevents the geometry around the
masses to be of the Schwarzschild type and leads to the introduction of a
cosmological constant. The study of the extension of the Kottler space-time
shows that there exists a non-static solution consisting of two static regions
surrounding the masses that match a Kantowski-Sachs expanding region on the
cosmological horizon. The comparison with a Swiss-Cheese construction is also
discussed.
|
[
{
"created": "Tue, 11 May 2010 11:58:01 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Feb 2011 09:38:13 GMT",
"version": "v2"
}
] |
2015-03-17
|
[
[
"Uzan",
"Jean-Philippe",
""
],
[
"Ellis",
"George F. R.",
""
],
[
"Larena",
"Julien",
""
]
] |
In order to understand how locally static configurations around gravitationally bound bodies can be embedded in an expanding universe, we investigate the solutions of general relativity describing a space-time whose spatial sections have the topology of a 3-sphere with two identical masses at the poles. We show that Israel junction conditions imply that two spherically symmetric static regions around the masses cannot be glued together. If one is interested in an exterior solution, this prevents the geometry around the masses to be of the Schwarzschild type and leads to the introduction of a cosmological constant. The study of the extension of the Kottler space-time shows that there exists a non-static solution consisting of two static regions surrounding the masses that match a Kantowski-Sachs expanding region on the cosmological horizon. The comparison with a Swiss-Cheese construction is also discussed.
|
1805.01265
|
Norman G\"urlebeck
|
Norman G\"urlebeck, Lisa W\"orner, Thilo Schuldt, Klaus D\"oringshoff,
Konstantin Gaul, Domenico Gerardi, Arne Grenzebach, Nandan Jha, Evgeny
Kovalchuk, Andreas Resch, Thijs Wendrich, Robert Berger, Sven Herrmann,
Ulrich Johann, Markus Krutzik, Achim Peters, Ernst M. Rasel and Claus
Braxmaier
|
BOOST -- A Satellite Mission to Test Lorentz Invariance Using
High-Performance Optical Frequency References
|
11 pages, 2 figures, accepted for publication in Phys. Rev. D
| null |
10.1103/PhysRevD.97.124051
| null |
gr-qc physics.ins-det physics.optics physics.space-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
BOOST (BOOst Symmetry Test) is a proposed satellite mission to search for
violations of Lorentz invariance by comparing two optical frequency references.
One is based on a long-term stable optical resonator and the other on a
hyperfine transition in molecular iodine. This mission will allow to determine
several parameters of the standard model extension in the electron sector up to
two orders of magnitude better than with the current best experiments. Here, we
will give an overview of the mission, the science case and the payload.
|
[
{
"created": "Thu, 3 May 2018 12:49:23 GMT",
"version": "v1"
}
] |
2018-08-01
|
[
[
"Gürlebeck",
"Norman",
""
],
[
"Wörner",
"Lisa",
""
],
[
"Schuldt",
"Thilo",
""
],
[
"Döringshoff",
"Klaus",
""
],
[
"Gaul",
"Konstantin",
""
],
[
"Gerardi",
"Domenico",
""
],
[
"Grenzebach",
"Arne",
""
],
[
"Jha",
"Nandan",
""
],
[
"Kovalchuk",
"Evgeny",
""
],
[
"Resch",
"Andreas",
""
],
[
"Wendrich",
"Thijs",
""
],
[
"Berger",
"Robert",
""
],
[
"Herrmann",
"Sven",
""
],
[
"Johann",
"Ulrich",
""
],
[
"Krutzik",
"Markus",
""
],
[
"Peters",
"Achim",
""
],
[
"Rasel",
"Ernst M.",
""
],
[
"Braxmaier",
"Claus",
""
]
] |
BOOST (BOOst Symmetry Test) is a proposed satellite mission to search for violations of Lorentz invariance by comparing two optical frequency references. One is based on a long-term stable optical resonator and the other on a hyperfine transition in molecular iodine. This mission will allow to determine several parameters of the standard model extension in the electron sector up to two orders of magnitude better than with the current best experiments. Here, we will give an overview of the mission, the science case and the payload.
|
1807.09818
|
Syed Moeez Hassan
|
Syed Moeez Hassan, Viqar Husain and Babar Qureshi
|
Gravity, time and varying constants
|
7 pages
| null | null |
MIT-CTP/5037
|
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
There are theories which implement the idea that the constants of nature may
be "time dependent." These introduce new fields representing "evolving
constants," in addition to physical fields. We argue that dynamical matter
coupling constants can arise naturally in non-perturbative matter-gravity
theories, after a choice of global time is made. We illustrate the idea in
scalar field cosmology with spatial volume as a global clock, and compute the
time dependence of the scalar mass and self-interaction coupling constants.
|
[
{
"created": "Wed, 25 Jul 2018 18:42:16 GMT",
"version": "v1"
}
] |
2018-07-27
|
[
[
"Hassan",
"Syed Moeez",
""
],
[
"Husain",
"Viqar",
""
],
[
"Qureshi",
"Babar",
""
]
] |
There are theories which implement the idea that the constants of nature may be "time dependent." These introduce new fields representing "evolving constants," in addition to physical fields. We argue that dynamical matter coupling constants can arise naturally in non-perturbative matter-gravity theories, after a choice of global time is made. We illustrate the idea in scalar field cosmology with spatial volume as a global clock, and compute the time dependence of the scalar mass and self-interaction coupling constants.
|
2408.04938
|
Robbert Scholtens
|
Robbert W. Scholtens, Marcello Seri, Holger Waalkens, Rien van de
Weygaert
|
Cosmic Anisotropy and Bianchi Characterization: Killing vector fields
and the implied finding of their metric frame
| null | null | null | null |
gr-qc astro-ph.CO math-ph math.MP
|
http://creativecommons.org/licenses/by/4.0/
|
On the largest scales the universe appears to be almost perfectly homogeneous
and isotropic, adhering to the cosmological principle. On smaller scales
inhomogeneities and anisotropies become increasingly prominent, reflecting the
origin, emergence and formation of structure in the Universe and its
cosmological impact. Also, a range of tensions between various cosmological
observations may suggest it to be necessary to explore the consequences of such
deviations from the ideal uniform universe. In this study, we restrict this to
an investigation of anisotropies on the nature of the Universe. This motivates
a more thorough understanding of the manifestation of anisotropy in
cosmological applications. When letting go of the assumption of isotropy,
spacetime metrics become homogeneous and completely anisotropic. As such, the
Lie algebras of Killing vector fields will be 3D, and fit into the so-called
9-part Bianchi classification. This work strives to, given a suitable 3D Lie
algebra of vector fields $\{\xi_a\}_{a=1,2,3}$ reconstruct the basis for a
metric on which this Lie algebra is Killing. Through finding a determining
equation for the frame invariant under $\{\xi_a\}$ and using the method of
characteristics to solve it, expressions for said invariant frame in terms of
the $\{\xi_a\}$ are obtained. This leads to general equations for the invariant
frame in terms of the $\{\xi_a\}$, organized by Bianchi class. Some examples
demonstrating this method are worked out.
|
[
{
"created": "Fri, 9 Aug 2024 08:37:36 GMT",
"version": "v1"
}
] |
2024-08-12
|
[
[
"Scholtens",
"Robbert W.",
""
],
[
"Seri",
"Marcello",
""
],
[
"Waalkens",
"Holger",
""
],
[
"van de Weygaert",
"Rien",
""
]
] |
On the largest scales the universe appears to be almost perfectly homogeneous and isotropic, adhering to the cosmological principle. On smaller scales inhomogeneities and anisotropies become increasingly prominent, reflecting the origin, emergence and formation of structure in the Universe and its cosmological impact. Also, a range of tensions between various cosmological observations may suggest it to be necessary to explore the consequences of such deviations from the ideal uniform universe. In this study, we restrict this to an investigation of anisotropies on the nature of the Universe. This motivates a more thorough understanding of the manifestation of anisotropy in cosmological applications. When letting go of the assumption of isotropy, spacetime metrics become homogeneous and completely anisotropic. As such, the Lie algebras of Killing vector fields will be 3D, and fit into the so-called 9-part Bianchi classification. This work strives to, given a suitable 3D Lie algebra of vector fields $\{\xi_a\}_{a=1,2,3}$ reconstruct the basis for a metric on which this Lie algebra is Killing. Through finding a determining equation for the frame invariant under $\{\xi_a\}$ and using the method of characteristics to solve it, expressions for said invariant frame in terms of the $\{\xi_a\}$ are obtained. This leads to general equations for the invariant frame in terms of the $\{\xi_a\}$, organized by Bianchi class. Some examples demonstrating this method are worked out.
|
1601.01384
|
Stephen Green
|
Pablo Bosch, Stephen R. Green, Luis Lehner
|
Nonlinear Evolution and Final Fate of Charged Anti-de Sitter Black Hole
Superradiant Instability
|
8 pages, 4 figures; V2: minor updates, added a reference; V3: updates
to match version accepted for publication in Physical Review Letters
|
Phys. Rev. Lett. 116, 141102 (2016)
|
10.1103/PhysRevLett.116.141102
| null |
gr-qc astro-ph.HE hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We describe the full nonlinear development of the superradiant instability
for a charged massless scalar field, coupled to general relativity and
electromagnetism, in the vicinity of a Reissner-Nordstrom-AdS black hole. The
presence of the negative cosmological constant provides a natural context for
considering perfectly reflecting boundary conditions and studying the dynamics
as the scalar field interacts repeatedly with the black hole. At early times,
small superradiant perturbations grow as expected from linearized studies.
Backreaction then causes the black hole to lose charge and mass until the
perturbation becomes nonsuperradiant, with the final state described by a
stable hairy black hole. For large gauge coupling, the instability extracts a
large amount of charge per unit mass, resulting in greater entropy increase. We
discuss the implications of the observed behavior for the general problem of
superradiance in black hole spacetimes.
|
[
{
"created": "Thu, 7 Jan 2016 03:20:12 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Jan 2016 20:23:02 GMT",
"version": "v2"
},
{
"created": "Wed, 30 Mar 2016 20:09:48 GMT",
"version": "v3"
}
] |
2016-04-13
|
[
[
"Bosch",
"Pablo",
""
],
[
"Green",
"Stephen R.",
""
],
[
"Lehner",
"Luis",
""
]
] |
We describe the full nonlinear development of the superradiant instability for a charged massless scalar field, coupled to general relativity and electromagnetism, in the vicinity of a Reissner-Nordstrom-AdS black hole. The presence of the negative cosmological constant provides a natural context for considering perfectly reflecting boundary conditions and studying the dynamics as the scalar field interacts repeatedly with the black hole. At early times, small superradiant perturbations grow as expected from linearized studies. Backreaction then causes the black hole to lose charge and mass until the perturbation becomes nonsuperradiant, with the final state described by a stable hairy black hole. For large gauge coupling, the instability extracts a large amount of charge per unit mass, resulting in greater entropy increase. We discuss the implications of the observed behavior for the general problem of superradiance in black hole spacetimes.
|
1511.06897
|
Brihaye Yves
|
Y. Brihaye, L. Ducobu
|
Black Holes with Scalar Hairs in Einstein-Gauss-Bonnet Gravity
|
16 pages, 9 figures
| null |
10.1142/S021827181650084X
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Einstein-Gauss-Bonnet gravity in five dimensions is extended by scalar
fields and the corresponding equations are reduced to a system of non-linear
differential equations. A large family of regular solutions of these equations
is shown to exist. Generically, these solutions are spinning black holes with
scalar hairs. They can be characterized (but not uniquely) by an horizon and an
angular velocity on this horizon. Taking particular limits the black holes
approach boson star or become extremal, in any case the limiting configurations
remain hairy.
|
[
{
"created": "Sat, 21 Nov 2015 16:43:49 GMT",
"version": "v1"
}
] |
2016-06-15
|
[
[
"Brihaye",
"Y.",
""
],
[
"Ducobu",
"L.",
""
]
] |
The Einstein-Gauss-Bonnet gravity in five dimensions is extended by scalar fields and the corresponding equations are reduced to a system of non-linear differential equations. A large family of regular solutions of these equations is shown to exist. Generically, these solutions are spinning black holes with scalar hairs. They can be characterized (but not uniquely) by an horizon and an angular velocity on this horizon. Taking particular limits the black holes approach boson star or become extremal, in any case the limiting configurations remain hairy.
|
0906.1928
|
Brihaye Yves
|
Yves Brihaye (Universite de Mons, Belgium)
|
Black holes, black strings and cosmological constant
|
31 pages including 24 figures; Extended version of a contribution to
the 418th WE-Heraeus Seminar, Bremen, 25-29 August 2008
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present a review of black holes and black string solutions available in
the $d$-dimensional Einstein and Einstein-Maxwell model in the presence of a
cosmological constant. Due to the cosmological constant, the equations do not
admit explicit solutions for generic values of the parameters and numerical
methods are necessary to construct the solutions. Several new features of the
solutions are discussed, namely their stability and the occurrence of
non-uniform black strings which depend non-trivially on the co-dimension. Black
string solutions are further constructed for the Einstein-Gauss-Bonnet model.
The influence of the Gauss-Bonnet term on the domain of existence of the black
strings is discussed in details.
|
[
{
"created": "Wed, 10 Jun 2009 13:05:42 GMT",
"version": "v1"
}
] |
2009-06-11
|
[
[
"Brihaye",
"Yves",
"",
"Universite de Mons, Belgium"
]
] |
We present a review of black holes and black string solutions available in the $d$-dimensional Einstein and Einstein-Maxwell model in the presence of a cosmological constant. Due to the cosmological constant, the equations do not admit explicit solutions for generic values of the parameters and numerical methods are necessary to construct the solutions. Several new features of the solutions are discussed, namely their stability and the occurrence of non-uniform black strings which depend non-trivially on the co-dimension. Black string solutions are further constructed for the Einstein-Gauss-Bonnet model. The influence of the Gauss-Bonnet term on the domain of existence of the black strings is discussed in details.
|
1612.07567
|
Juan Carlos Degollado
|
Claudia Moreno, Juan Carlos Degollado and Dario Nunez
|
Gravitational and electromagnetic signatures of accretion into a charged
black hole
|
17 pages, 9 figures
| null |
10.1007/s10714-017-2244-5
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present the derivation and the solutions to the coupled electromagnetic
and gravitational perturbations with sources in a charged black hole
background. We work in the so called ghost gauge and consider as source of the
perturbations the infall of radial currents. In this way, we study a system in
which it is provoked a response involving both, gravitational and
electromagnetic waves, which allows us to analyze the dependence between them.
We solve numerically the wave equations that describe both signals,
characterize the waveforms and study the relation between the input parameters
of the infalling matter with those of the gravitational and electromagnetic
responses.
|
[
{
"created": "Thu, 22 Dec 2016 12:20:05 GMT",
"version": "v1"
}
] |
2017-06-21
|
[
[
"Moreno",
"Claudia",
""
],
[
"Degollado",
"Juan Carlos",
""
],
[
"Nunez",
"Dario",
""
]
] |
We present the derivation and the solutions to the coupled electromagnetic and gravitational perturbations with sources in a charged black hole background. We work in the so called ghost gauge and consider as source of the perturbations the infall of radial currents. In this way, we study a system in which it is provoked a response involving both, gravitational and electromagnetic waves, which allows us to analyze the dependence between them. We solve numerically the wave equations that describe both signals, characterize the waveforms and study the relation between the input parameters of the infalling matter with those of the gravitational and electromagnetic responses.
|
gr-qc/9604017
|
Int. Lab. HTSC and Sse
|
Sergiu I. Vacaru
|
Nearly Autoparallel Maps, Tensor Integral and Conservation Laws in
Locally Anisotrpoic Spaces
|
38 pages, Revtex
|
Extension of a paper in "Romanian J. Phys" 39 (1994) 37-52
| null | null |
gr-qc dg-ga math.DG
| null |
We formulate the theory of nearly autoparallel maps (generalizing conformal
transforms) of locally anisotropic spaces and define the nearly autoparallel
integration as the inverse operation to both covariant derivation and
deformation of connections by nearly autoparallel maps. By using this geometric
formalism we consider a variant of solution of the problem of formulation of
conservation laws for locally anisotropic gravity. We note that locally
anisotropic spases contain as particular cases various extensions of
Kaluza--Klein, generalized Lagrange and Finsler spaces.
|
[
{
"created": "Mon, 8 Apr 1996 08:29:23 GMT",
"version": "v1"
}
] |
2016-08-31
|
[
[
"Vacaru",
"Sergiu I.",
""
]
] |
We formulate the theory of nearly autoparallel maps (generalizing conformal transforms) of locally anisotropic spaces and define the nearly autoparallel integration as the inverse operation to both covariant derivation and deformation of connections by nearly autoparallel maps. By using this geometric formalism we consider a variant of solution of the problem of formulation of conservation laws for locally anisotropic gravity. We note that locally anisotropic spases contain as particular cases various extensions of Kaluza--Klein, generalized Lagrange and Finsler spaces.
|
2103.13599
|
Yunqi Liu
|
Cheng-Yong Zhang, Peng Liu, Yunqi Liu, Chao Niu, Bin Wang
|
Dynamical charged black hole spontaneous scalarization in Anti-de Sitter
spacetimes
| null | null |
10.1103/PhysRevD.104.084089
| null |
gr-qc
|
http://creativecommons.org/licenses/by-nc-sa/4.0/
|
We study the fully nonlinear dynamics of black hole spontaneous
scalarizations in Einstein-Maxwell scalar theory with coupling function
$f(\phi)=e^{-b\phi^{2}}$, which can transform usual Reissner-Nordstr\"om
Anti-de Sitter (RN-AdS) black holes into hairy black holes. Fixing the
Arnowitt-Deser-Misner mass of the system, the initial scalar perturbation will
destroy the original RN-AdS black hole and turn it into a hairy black hole
provided that the constant $-b$ in the coupling function and the charge of the
original black hole are sufficiently large, while the cosmological constant is
small enough. In the scalarization process, we observe that the black hole
irreducible mass initially increases exponentially, then it approaches to and
finally saturates at a finite value. Choosing stronger coupling and larger
black hole charge, we find that the black hole mass exponentially grows earlier
and it takes a longer time for a hairy black hole to be developed and
stabilized. We further examine phase structure properties in the scalarization
process and confirm the observations in the non-linear dynamical study.
|
[
{
"created": "Thu, 25 Mar 2021 04:12:04 GMT",
"version": "v1"
}
] |
2021-11-10
|
[
[
"Zhang",
"Cheng-Yong",
""
],
[
"Liu",
"Peng",
""
],
[
"Liu",
"Yunqi",
""
],
[
"Niu",
"Chao",
""
],
[
"Wang",
"Bin",
""
]
] |
We study the fully nonlinear dynamics of black hole spontaneous scalarizations in Einstein-Maxwell scalar theory with coupling function $f(\phi)=e^{-b\phi^{2}}$, which can transform usual Reissner-Nordstr\"om Anti-de Sitter (RN-AdS) black holes into hairy black holes. Fixing the Arnowitt-Deser-Misner mass of the system, the initial scalar perturbation will destroy the original RN-AdS black hole and turn it into a hairy black hole provided that the constant $-b$ in the coupling function and the charge of the original black hole are sufficiently large, while the cosmological constant is small enough. In the scalarization process, we observe that the black hole irreducible mass initially increases exponentially, then it approaches to and finally saturates at a finite value. Choosing stronger coupling and larger black hole charge, we find that the black hole mass exponentially grows earlier and it takes a longer time for a hairy black hole to be developed and stabilized. We further examine phase structure properties in the scalarization process and confirm the observations in the non-linear dynamical study.
|
1603.01286
|
Kenta Hotokezaka
|
Kenta Hotokezaka, Koutarou Kyutoku, Yu-ichiro Sekiguchi, Masaru
Shibata
|
Measurability of the tidal deformability by gravitational waves from
coalescing binary neutron stars
|
18 pages, 9 figures, accepted for publication in PRD
| null |
10.1103/PhysRevD.93.064082
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Combining new gravitational waveforms derived by long-term (14--16 orbits)
numerical-relativity simulations with waveforms by an effective-one-body (EOB)
formalism for coalescing binary neutron stars, we construct hybrid waveforms
and estimate the measurability for the dimensionless tidal deformability of the
neutron stars, $\Lambda$, by advanced gravitational-wave detectors. We focus on
the equal-mass case with the total mass $2.7M_\odot$. We find that for an event
at a hypothetical effective distance of $D_{\rm eff}=200$ Mpc, the
distinguishable difference in the dimensionless tidal deformability will be
$\approx 100$, 400, and 800 at 1-$\sigma$, 2-$\sigma$, and 3-$\sigma$ levels,
respectively, for advanced LIGO. If the true equation of state is stiff and the
typical neutron-star radius is $R \gtrsim 13 $ km, our analysis suggests that
the radius will be constrained within $\approx 1$ km at 2-$\sigma$ level for an
event at $D_{\rm eff}=200$ Mpc. On the other hand, if the true equation of
state is soft and the typical neutron-star radius is $R\lesssim 12$ km , it
will be difficult to narrow down the equation of state among many soft ones,
although it is still possible to discriminate the true one from stiff equations
of state with $R\gtrsim 13$ km. We also find that gravitational waves from
binary neutron stars will be distinguished from those from spinless binary
black holes at more than 2-$\sigma$ level for an event at $D_{\rm eff}=200$
Mpc. The validity of the EOB formalism, Taylor-T4, and Taylor-F2 approximants
as the inspiral waveform model is also examined.
|
[
{
"created": "Thu, 3 Mar 2016 21:26:03 GMT",
"version": "v1"
}
] |
2016-04-20
|
[
[
"Hotokezaka",
"Kenta",
""
],
[
"Kyutoku",
"Koutarou",
""
],
[
"Sekiguchi",
"Yu-ichiro",
""
],
[
"Shibata",
"Masaru",
""
]
] |
Combining new gravitational waveforms derived by long-term (14--16 orbits) numerical-relativity simulations with waveforms by an effective-one-body (EOB) formalism for coalescing binary neutron stars, we construct hybrid waveforms and estimate the measurability for the dimensionless tidal deformability of the neutron stars, $\Lambda$, by advanced gravitational-wave detectors. We focus on the equal-mass case with the total mass $2.7M_\odot$. We find that for an event at a hypothetical effective distance of $D_{\rm eff}=200$ Mpc, the distinguishable difference in the dimensionless tidal deformability will be $\approx 100$, 400, and 800 at 1-$\sigma$, 2-$\sigma$, and 3-$\sigma$ levels, respectively, for advanced LIGO. If the true equation of state is stiff and the typical neutron-star radius is $R \gtrsim 13 $ km, our analysis suggests that the radius will be constrained within $\approx 1$ km at 2-$\sigma$ level for an event at $D_{\rm eff}=200$ Mpc. On the other hand, if the true equation of state is soft and the typical neutron-star radius is $R\lesssim 12$ km , it will be difficult to narrow down the equation of state among many soft ones, although it is still possible to discriminate the true one from stiff equations of state with $R\gtrsim 13$ km. We also find that gravitational waves from binary neutron stars will be distinguished from those from spinless binary black holes at more than 2-$\sigma$ level for an event at $D_{\rm eff}=200$ Mpc. The validity of the EOB formalism, Taylor-T4, and Taylor-F2 approximants as the inspiral waveform model is also examined.
|
2001.06261
|
Xiang-Hua Zhai
|
Hai-Feng Ding and Xiang-Hua Zhai
|
Entropies and The First Laws of Black Hole Thermodynamics in
Einstein-aether-Maxwell Theory
|
23 pages, version appeared in Class. Quantum Grav
|
Class. Quantum Grav. 37 (2020) 185015
|
10.1088/1361-6382/aba31d
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Using the solution phase space method, we investigate the thermodynamics of
black holes in Einstein-aether-Maxwell theory, for which the traditional Wald
method (covariant phase space method) fails. We show the first laws of
thermodynamics and definitive entropy expressions at both Killing and universal
horizons for some examples of exact black hole solutions, including
3-dimensional static charged quasi-BTZ black hole, two 4-dimensional static
charged black holes and 3-dimensional rotating solution. At Killing horizons
the entropies are exactly one quarter of the horizon area, but at universal
horizons of 3-dimensional black holes, the entropies have a corrected term in
addition to the one proportional to the horizon area.
|
[
{
"created": "Fri, 17 Jan 2020 12:30:40 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Aug 2020 13:57:57 GMT",
"version": "v2"
}
] |
2020-08-25
|
[
[
"Ding",
"Hai-Feng",
""
],
[
"Zhai",
"Xiang-Hua",
""
]
] |
Using the solution phase space method, we investigate the thermodynamics of black holes in Einstein-aether-Maxwell theory, for which the traditional Wald method (covariant phase space method) fails. We show the first laws of thermodynamics and definitive entropy expressions at both Killing and universal horizons for some examples of exact black hole solutions, including 3-dimensional static charged quasi-BTZ black hole, two 4-dimensional static charged black holes and 3-dimensional rotating solution. At Killing horizons the entropies are exactly one quarter of the horizon area, but at universal horizons of 3-dimensional black holes, the entropies have a corrected term in addition to the one proportional to the horizon area.
|
gr-qc/9703018
|
Chris Chambers
|
Chris M. Chambers, William A. Hiscock and Brett Taylor (Montana State
University)
|
Spinning Down a Black Hole With Scalar Fields
|
4 pages (including 3 postscript figures), Revtex, uses epsf.tex,
twocolumn.sty and header.sty (included). Submitted to Physical Review Letters
|
Phys.Rev.Lett. 78 (1997) 3249-3251
|
10.1103/PhysRevLett.78.3249
|
MSUPHY97.06
|
gr-qc
| null |
We study the evolution of a Kerr black hole emitting scalar radiation via the
Hawking process. We show that the rate at which mass and angular momentum are
lost by the black hole leads to a final evolutionary state with nonzero angular
momentum, namely $a/M \approx 0.555$.
|
[
{
"created": "Thu, 6 Mar 1997 22:49:12 GMT",
"version": "v1"
}
] |
2009-10-30
|
[
[
"Chambers",
"Chris M.",
"",
"Montana State\n University"
],
[
"Hiscock",
"William A.",
"",
"Montana State\n University"
],
[
"Taylor",
"Brett",
"",
"Montana State\n University"
]
] |
We study the evolution of a Kerr black hole emitting scalar radiation via the Hawking process. We show that the rate at which mass and angular momentum are lost by the black hole leads to a final evolutionary state with nonzero angular momentum, namely $a/M \approx 0.555$.
|
1611.10313
|
Alan Kostelecky
|
Alan Kostelecky, Matthew Mewes
|
Testing local Lorentz invariance with short-range gravity
|
7 pages
|
Phys.Lett.B766: 137-143, 2017
|
10.1016/j.physletb.2016.12.062
|
IUHET 622, November 2016
|
gr-qc hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Newton limit of gravity is studied in the presence of Lorentz-violating
gravitational operators of arbitrary mass dimension. The linearized modified
Einstein equations are obtained and the perturbative solutions are constructed
and characterized. We develop a formalism for data analysis in laboratory
experiments testing gravity at short range and demonstrate that these tests
provide unique sensitivity to deviations from local Lorentz invariance.
|
[
{
"created": "Wed, 30 Nov 2016 19:05:56 GMT",
"version": "v1"
}
] |
2017-01-17
|
[
[
"Kostelecky",
"Alan",
""
],
[
"Mewes",
"Matthew",
""
]
] |
The Newton limit of gravity is studied in the presence of Lorentz-violating gravitational operators of arbitrary mass dimension. The linearized modified Einstein equations are obtained and the perturbative solutions are constructed and characterized. We develop a formalism for data analysis in laboratory experiments testing gravity at short range and demonstrate that these tests provide unique sensitivity to deviations from local Lorentz invariance.
|
gr-qc/0110061
|
V. Kurbanova
|
A. B. Balakin, V. Kurbanova (Kazan State University)
|
Relativistic Dynamics of Vector Bosons in the Field of Gravitational
Radiation
|
10 pages, no figures, Tex
|
Found.Phys. 31 (2001) 1039-1049
| null | null |
gr-qc
| null |
We consider a model of the state evolution of relativistic vector bosons,
which includes both the dynamical equations for the particle four-velocity and
the equations for the polarization four-vector evolution in the field of a
nonlinear plane gravitational wave. In addition to the gravitational minimal
coupling, tidal forces linear in curvature tensor are suggested to drive the
particle state evolution. The exact solutions of the evolutionary equations are
obtained. Birefringence and tidal deviations from the geodesic motion are
discussed.
|
[
{
"created": "Fri, 12 Oct 2001 08:02:34 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Oct 2001 06:40:54 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Balakin",
"A. B.",
"",
"Kazan State University"
],
[
"Kurbanova",
"V.",
"",
"Kazan State University"
]
] |
We consider a model of the state evolution of relativistic vector bosons, which includes both the dynamical equations for the particle four-velocity and the equations for the polarization four-vector evolution in the field of a nonlinear plane gravitational wave. In addition to the gravitational minimal coupling, tidal forces linear in curvature tensor are suggested to drive the particle state evolution. The exact solutions of the evolutionary equations are obtained. Birefringence and tidal deviations from the geodesic motion are discussed.
|
gr-qc/9806061
|
Robert V. Gentry
|
Robert V. Gentry and David W. Gentry
|
The Genuine Cosmic Rosetta
|
9 pages LaTeX, no figures
| null | null | null |
gr-qc astro-ph
| null |
Reexamination of general relativistic experimental results shows the universe
is governed by Einstein's static-spacetime general relativity instead of
Friedmann-Lemaitre expanding-spacetime general relativity. The absence of
expansion redshifts in a static-spacetime universe suggests a reevaluation of
the present cosmology is needed.
|
[
{
"created": "Sun, 14 Jun 1998 23:00:45 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Gentry",
"Robert V.",
""
],
[
"Gentry",
"David W.",
""
]
] |
Reexamination of general relativistic experimental results shows the universe is governed by Einstein's static-spacetime general relativity instead of Friedmann-Lemaitre expanding-spacetime general relativity. The absence of expansion redshifts in a static-spacetime universe suggests a reevaluation of the present cosmology is needed.
|
0911.0604
|
Eyo Ita III
|
Eyo Eyo Ita III
|
CDJ formulation from the instanton representation of Plebanski gravity
|
4 pages. Submitting for proceedings for the 10th International
Conference on Gravitation, Astrophysics and Cosmology, Vietnam
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We show that a certain action which gives rise to the pure spin connection
formulation of gravity by CDJ can be consistently derived from the action for
the instanton representation of Plebanski gravity. This is an illustrative
example of when certain symmetries of the basic fields commute with the
symmetries of the equations of motion.
|
[
{
"created": "Tue, 3 Nov 2009 20:59:13 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Nov 2009 18:15:02 GMT",
"version": "v2"
},
{
"created": "Fri, 7 May 2010 19:54:13 GMT",
"version": "v3"
},
{
"created": "Wed, 29 Dec 2010 23:36:14 GMT",
"version": "v4"
},
{
"created": "Mon, 27 Feb 2012 18:49:47 GMT",
"version": "v5"
}
] |
2012-02-28
|
[
[
"Ita",
"Eyo Eyo",
"III"
]
] |
We show that a certain action which gives rise to the pure spin connection formulation of gravity by CDJ can be consistently derived from the action for the instanton representation of Plebanski gravity. This is an illustrative example of when certain symmetries of the basic fields commute with the symmetries of the equations of motion.
|
1806.01941
|
Antonio Enea Romano
|
Antonio Enea Romano, Sergio A. Vallejo Pena
|
The MESS of cosmological perturbations
|
We study the MESS of cosmological perturbations, version accepted in
Physics Letters B
| null |
10.1016/j.physletb.2018.08.016
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We introduce two new effective quantities for the study of comoving curvature
perturbations $\zeta$: the space dependent effective sound speed (SESS) and the
momentum dependent effective sound speed (MESS) . We use the SESS and the MESS
to derive a new set of equations which can be applied to any system described
by an effective stress-energy-momentum tensor (EST), including multi-fields
systems, supergravity and modified gravity theories. We show that this approach
is completely equivalent to the standard one and it has the advantage of
requiring to solve only one differential equation for $\zeta$ instead of a
system, without the need of explicitly computing the evolution of entropy
perturbations. The equations are valid for perturbations respect to any
arbitrary flat spatially homogeneous background, including any inflationary and
bounce model.
As an application we derive the equation for $\zeta$ for multi-fields $KGB$
models and show that observed features of the primordial curvature perturbation
spectrum are compatible with the effects of an appropriate local variation of
the MESS in momentum space. The MESS is the natural quantity to parametrize in
a model independent way the effects produced on curvature perturbations by
multi-fields systems, particle production and modified gravity theories and
could be conveniently used in the analysis of LSS observations, such as the
ones from the upcoming EUCLID mission or CMB radiation measurements.
|
[
{
"created": "Tue, 5 Jun 2018 21:38:58 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Aug 2018 18:11:51 GMT",
"version": "v2"
}
] |
2018-08-28
|
[
[
"Romano",
"Antonio Enea",
""
],
[
"Pena",
"Sergio A. Vallejo",
""
]
] |
We introduce two new effective quantities for the study of comoving curvature perturbations $\zeta$: the space dependent effective sound speed (SESS) and the momentum dependent effective sound speed (MESS) . We use the SESS and the MESS to derive a new set of equations which can be applied to any system described by an effective stress-energy-momentum tensor (EST), including multi-fields systems, supergravity and modified gravity theories. We show that this approach is completely equivalent to the standard one and it has the advantage of requiring to solve only one differential equation for $\zeta$ instead of a system, without the need of explicitly computing the evolution of entropy perturbations. The equations are valid for perturbations respect to any arbitrary flat spatially homogeneous background, including any inflationary and bounce model. As an application we derive the equation for $\zeta$ for multi-fields $KGB$ models and show that observed features of the primordial curvature perturbation spectrum are compatible with the effects of an appropriate local variation of the MESS in momentum space. The MESS is the natural quantity to parametrize in a model independent way the effects produced on curvature perturbations by multi-fields systems, particle production and modified gravity theories and could be conveniently used in the analysis of LSS observations, such as the ones from the upcoming EUCLID mission or CMB radiation measurements.
|
1811.10917
|
Nezihe Uzun
|
Nezihe Uzun
|
Reduced phase space optics for general relativity: Symplectic ray bundle
transfer
|
39 pages, 2 figures
|
Classical and Quantum Gravity, Volume 37, Number 4, Page 045002,
(2020)
|
10.1088/1361-6382/ab60b5
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In the paraxial regime of Newtonian optics, propagation of an ensemble of
rays is represented by a symplectic ABCD transfer matrix defined on a reduced
phase space. Here, we present its analogue for general relativity. Starting
from simultaneously applied null geodesic actions for two curves, we obtain a
geodesic deviation action up to quadratic order. We achieve this by following a
preexisting method constructed via Synge's world function. We find the
corresponding Hamiltonian function and the reduced phase space coordinates that
are composed of the components of the Jacobi fields projected on an
observational screen. Our thin ray bundle transfer matrix is then obtained
through the matrix representation of the Lie operator associated with this
quadratic Hamiltonian. Moreover, Etherington's distance reciprocity between any
two points is shown to be equivalent to the symplecticity conditions of our ray
bundle transfer matrix. We further interpret the bundle propagation as a free
canonical transformation with a generating function that is equal to the
geodesic deviation action. We present it in the form of matrix inner products.
A phase space distribution function and the associated Liouville equation is
also provided. Finally, we briefly sketch the potential applications of our
construction. Those include reduced phase space and null bundle averaging;
factorization of light propagation in any spacetime uniquely into its thin
lens, pure magnifier and fractional Fourier transformer components; wavization
of the ray bundle; reduced polarization optics and autonomization of the bundle
propagation on the phase space to find its invariants and obtain the stability
analysis.
|
[
{
"created": "Tue, 27 Nov 2018 11:25:42 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Jan 2020 17:35:27 GMT",
"version": "v2"
}
] |
2020-01-28
|
[
[
"Uzun",
"Nezihe",
""
]
] |
In the paraxial regime of Newtonian optics, propagation of an ensemble of rays is represented by a symplectic ABCD transfer matrix defined on a reduced phase space. Here, we present its analogue for general relativity. Starting from simultaneously applied null geodesic actions for two curves, we obtain a geodesic deviation action up to quadratic order. We achieve this by following a preexisting method constructed via Synge's world function. We find the corresponding Hamiltonian function and the reduced phase space coordinates that are composed of the components of the Jacobi fields projected on an observational screen. Our thin ray bundle transfer matrix is then obtained through the matrix representation of the Lie operator associated with this quadratic Hamiltonian. Moreover, Etherington's distance reciprocity between any two points is shown to be equivalent to the symplecticity conditions of our ray bundle transfer matrix. We further interpret the bundle propagation as a free canonical transformation with a generating function that is equal to the geodesic deviation action. We present it in the form of matrix inner products. A phase space distribution function and the associated Liouville equation is also provided. Finally, we briefly sketch the potential applications of our construction. Those include reduced phase space and null bundle averaging; factorization of light propagation in any spacetime uniquely into its thin lens, pure magnifier and fractional Fourier transformer components; wavization of the ray bundle; reduced polarization optics and autonomization of the bundle propagation on the phase space to find its invariants and obtain the stability analysis.
|
1810.02159
|
Ra\'ul Carballo-Rubio
|
Stephon Alexander and Ra\'ul Carballo-Rubio
|
Topological Features of the Quantum Vacuum
|
7 double-column pages + references, no figures
|
Phys. Rev. D 101, 024058 (2020)
|
10.1103/PhysRevD.101.024058
| null |
gr-qc hep-ex hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A central aspect of the cosmological constant problem is to understand why
vacuum energy does not gravitate. In order to account for this observation,
while allowing for nontrivial dynamics of the quantum vacuum, we motivate a
novel background independent theory of gravity. The theory is an extension of
unimodular gravity that is described in geometric terms by means of a conformal
(light-cone) structure and differential forms of degree one and two. We show
that the subset of the classical field equations describing the dynamics of
matter degrees of freedom and the conformal structure of spacetime are
equivalent to that of unimodular gravity. The sector with vanishing matter
fields and flat conformal structure is governed by the field equations of BF
theory and contains topological invariants that are influenced by quantum
vacuum fluctuations. Perturbative deviations from this sector lead to classical
solutions that necessarily display relatively small values of the cosmological
constant with respect to the would-be contribution of quantum vacuum
fluctuations. This feature that goes beyond general relativity (and unimodular
gravity) offers an interpretation of the smallness of the currently observed
cosmological constant.
|
[
{
"created": "Thu, 4 Oct 2018 11:56:36 GMT",
"version": "v1"
}
] |
2020-02-05
|
[
[
"Alexander",
"Stephon",
""
],
[
"Carballo-Rubio",
"Raúl",
""
]
] |
A central aspect of the cosmological constant problem is to understand why vacuum energy does not gravitate. In order to account for this observation, while allowing for nontrivial dynamics of the quantum vacuum, we motivate a novel background independent theory of gravity. The theory is an extension of unimodular gravity that is described in geometric terms by means of a conformal (light-cone) structure and differential forms of degree one and two. We show that the subset of the classical field equations describing the dynamics of matter degrees of freedom and the conformal structure of spacetime are equivalent to that of unimodular gravity. The sector with vanishing matter fields and flat conformal structure is governed by the field equations of BF theory and contains topological invariants that are influenced by quantum vacuum fluctuations. Perturbative deviations from this sector lead to classical solutions that necessarily display relatively small values of the cosmological constant with respect to the would-be contribution of quantum vacuum fluctuations. This feature that goes beyond general relativity (and unimodular gravity) offers an interpretation of the smallness of the currently observed cosmological constant.
|
gr-qc/0011079
|
Vanessa Carvalho De Andrade
|
V. C. de Andrade, L. C. T. Guillen and J. G. Pereira
|
Teleparallel Gravity and the Gravitational Energy-Momentum Density
|
6 pages. Contribuition to IX Marcel Grossmann Meeting, Rome 2000
| null | null | null |
gr-qc
| null |
In the context of the teleparallel equivalent of general relativity, we show
that the energy-momentum density for the gravitational field can be described
by a true spacetime tensor. It is also invariant under local (gauge)
translations of the tangent space coordinates, but transforms covariantly only
under global Lorentz transformations. When the gauge gravitational field
equation is written in a purely spacetime form, it becomes the teleparallel
equivalent of Einstein's equation, and we recover M{\o}ller's expression for
the canonical gravitational energy-momentum pseudotensor.
|
[
{
"created": "Wed, 22 Nov 2000 13:51:50 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"de Andrade",
"V. C.",
""
],
[
"Guillen",
"L. C. T.",
""
],
[
"Pereira",
"J. G.",
""
]
] |
In the context of the teleparallel equivalent of general relativity, we show that the energy-momentum density for the gravitational field can be described by a true spacetime tensor. It is also invariant under local (gauge) translations of the tangent space coordinates, but transforms covariantly only under global Lorentz transformations. When the gauge gravitational field equation is written in a purely spacetime form, it becomes the teleparallel equivalent of Einstein's equation, and we recover M{\o}ller's expression for the canonical gravitational energy-momentum pseudotensor.
|
1206.3903
|
Carlo Rovelli
|
Marios Christodoulou, Aldo Riello, Carlo Rovelli
|
How to detect an anti-spacetime
|
Article awarded with an "Honorable Mention" from the 2012 Gravity
Foundation Award. 6 pages, 8 (pretty) figures
| null |
10.1142/S021827181242014X
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Is it possible, in principle, to measure the sign of the Lapse? We show that
fermion dynamics distinguishes spacetimes having the same metric but different
tetrads, for instance a Lapse with opposite sign. This sign might be a physical
quantity not captured by the metric. We discuss its possible role in quantum
gravity.
|
[
{
"created": "Mon, 18 Jun 2012 12:22:58 GMT",
"version": "v1"
}
] |
2015-06-05
|
[
[
"Christodoulou",
"Marios",
""
],
[
"Riello",
"Aldo",
""
],
[
"Rovelli",
"Carlo",
""
]
] |
Is it possible, in principle, to measure the sign of the Lapse? We show that fermion dynamics distinguishes spacetimes having the same metric but different tetrads, for instance a Lapse with opposite sign. This sign might be a physical quantity not captured by the metric. We discuss its possible role in quantum gravity.
|
2004.07120
|
Mihai Marciu C
|
Mihai Marciu
|
Dynamical aspects for scalar fields coupled to cubic contractions of the
Riemann tensor
| null |
Phys. Rev. D 102, 023517 (2020)
|
10.1103/PhysRevD.102.023517
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The paper studies a new type of dark energy, a scalar field with positive or
negative kinetic energy, generically coupled to a term which is composed by
specific contractions of the Riemann tensor. After presenting the resulting
field equations, we have analyzed the physical characteristics of the
corresponding model by implementing the linear stability theory. In the case of
an exponential coupling function and exponential potential energy we have
deduced the phase space characteristics, analyzing the critical points obtained
which can represent specific eras in the evolution of the Universe. The
analytical study is showing that this model can represent a feasible
cosmological setup, having various epochs which correspond to stiff-fluid,
matter domination, and dark energy eras, pointing towards the emergence of the
accelerated expansion as a geometrical effect.
|
[
{
"created": "Wed, 15 Apr 2020 14:39:00 GMT",
"version": "v1"
}
] |
2020-07-15
|
[
[
"Marciu",
"Mihai",
""
]
] |
The paper studies a new type of dark energy, a scalar field with positive or negative kinetic energy, generically coupled to a term which is composed by specific contractions of the Riemann tensor. After presenting the resulting field equations, we have analyzed the physical characteristics of the corresponding model by implementing the linear stability theory. In the case of an exponential coupling function and exponential potential energy we have deduced the phase space characteristics, analyzing the critical points obtained which can represent specific eras in the evolution of the Universe. The analytical study is showing that this model can represent a feasible cosmological setup, having various epochs which correspond to stiff-fluid, matter domination, and dark energy eras, pointing towards the emergence of the accelerated expansion as a geometrical effect.
|
1503.05151
|
Massimiliano Rinaldi
|
Guido Cognola, Massimiliano Rinaldi, Luciano Vanzo, and Sergio Zerbini
|
Thermodynamics of topological black holes in $R^{2}$ gravity
|
Accepted for publication in Physical Review D
|
Phys. Rev. D 91, 104004 (2015)
|
10.1103/PhysRevD.91.104004
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study topological black hole solutions of the simplest quadratic gravity
action and we find that two classes are allowed. The first is asymptotically
flat and mimics the Reissner-Nordstr\"om solution, while the second is
asymptotically de Sitter or anti-de Sitter. In both classes, the geometry of
the horizon can be spherical, toroidal or hyperbolic. We focus in particular on
the thermodynamical properties of the asymptotically anti-de Sitter solutions
and we compute the entropy and the internal energy with Euclidean methods. We
find that the entropy is positive-definite for all horizon geometries and this
allows to formulate a consistent generalized first law of black hole
thermodynamics, which keeps in account the presence of two arbitrary parameters
in the solution. The two-dimensional thermodynamical state space is fully
characterized by the underlying scale invariance of the action and it has the
structure of a projective space. We find a kind of duality between black holes
and other objects with the same entropy in the state space. We briefly discuss
the extension of our results to more general quadratic actions.
|
[
{
"created": "Tue, 17 Mar 2015 18:23:48 GMT",
"version": "v1"
},
{
"created": "Mon, 23 Mar 2015 14:50:00 GMT",
"version": "v2"
},
{
"created": "Tue, 21 Apr 2015 16:20:11 GMT",
"version": "v3"
}
] |
2015-05-13
|
[
[
"Cognola",
"Guido",
""
],
[
"Rinaldi",
"Massimiliano",
""
],
[
"Vanzo",
"Luciano",
""
],
[
"Zerbini",
"Sergio",
""
]
] |
We study topological black hole solutions of the simplest quadratic gravity action and we find that two classes are allowed. The first is asymptotically flat and mimics the Reissner-Nordstr\"om solution, while the second is asymptotically de Sitter or anti-de Sitter. In both classes, the geometry of the horizon can be spherical, toroidal or hyperbolic. We focus in particular on the thermodynamical properties of the asymptotically anti-de Sitter solutions and we compute the entropy and the internal energy with Euclidean methods. We find that the entropy is positive-definite for all horizon geometries and this allows to formulate a consistent generalized first law of black hole thermodynamics, which keeps in account the presence of two arbitrary parameters in the solution. The two-dimensional thermodynamical state space is fully characterized by the underlying scale invariance of the action and it has the structure of a projective space. We find a kind of duality between black holes and other objects with the same entropy in the state space. We briefly discuss the extension of our results to more general quadratic actions.
|
gr-qc/9712094
|
Stanislav Alexeyev
|
S.O.Alexeyev and M.V.Sazhin (Sternberg Astronomical Institute, Moscow
State University)
|
Some Aspects of Four Dimensional Black Hole Solutions in Gauss-Bonnet
Extended String Gravity
|
17 pages, 7 Postscript figures, uses mprocl.sty and epsf.sty. Talk
given at the "Discussion Meeting on Physics of Black Holes", Bangalore,
India, December 8-10, 1997
| null | null | null |
gr-qc
| null |
An internal singularity of a string four-dimensional black hole with second
order curvature corrections is discussed. A restriction to a minimal size of a
neutral black hole is obtained in the frame of the model considered. Vacuum
polarization of the surrounding space-time caused by this minimal-size black
hole is also discussed.
|
[
{
"created": "Wed, 24 Dec 1997 19:53:47 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Alexeyev",
"S. O.",
"",
"Sternberg Astronomical Institute, Moscow\n State University"
],
[
"Sazhin",
"M. V.",
"",
"Sternberg Astronomical Institute, Moscow\n State University"
]
] |
An internal singularity of a string four-dimensional black hole with second order curvature corrections is discussed. A restriction to a minimal size of a neutral black hole is obtained in the frame of the model considered. Vacuum polarization of the surrounding space-time caused by this minimal-size black hole is also discussed.
|
2406.10692
|
Sudip Mishra
|
Soumya Chakraborty, Sudip Mishra and Subenoy Chakraborty
|
Dynamical system analysis of quintessence dark energy model
| null | null |
10.1142/S0219887824502505
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
Our work deals with the dynamical system analysis of quintessence dark energy
scalar field model with exponential potential. A dynamical system analysis has
been applied at the background level. Using suitable transformation of
variables, the evolution equations are reduced to an autonomous system for
exponential form of the scalar potential. The critical points are analyzed with
center manifold theory and stability has been discussed by using Schwarzian
derivative. Finally, cosmological implications of the critical points are
discussed and it is found that the stability of the late-time attractor changes
for quintessence dark energy model.
|
[
{
"created": "Sat, 15 Jun 2024 17:10:38 GMT",
"version": "v1"
}
] |
2024-06-18
|
[
[
"Chakraborty",
"Soumya",
""
],
[
"Mishra",
"Sudip",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] |
Our work deals with the dynamical system analysis of quintessence dark energy scalar field model with exponential potential. A dynamical system analysis has been applied at the background level. Using suitable transformation of variables, the evolution equations are reduced to an autonomous system for exponential form of the scalar potential. The critical points are analyzed with center manifold theory and stability has been discussed by using Schwarzian derivative. Finally, cosmological implications of the critical points are discussed and it is found that the stability of the late-time attractor changes for quintessence dark energy model.
|
1912.07609
|
Leo Stein
|
Leo C. Stein, Niels Warburton
|
The location of the last stable orbit in Kerr spacetime
|
11+4 pages, 6 figures, 1 ancillary Mathematica file. v2: Minor edits,
matched version published in PRD. Code available at https://bhptoolkit.org/
|
Phys. Rev. D 101, 064007 (2020)
|
10.1103/PhysRevD.101.064007
| null |
gr-qc astro-ph.HE hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Black hole spacetimes, like the Kerr spacetime, admit both stable and
plunging orbits, separated in parameter space by the separatrix. Determining
the location of the separatrix is of fundamental interest in understanding
black holes, and is of crucial importance for modeling extreme mass-ratio
inspirals. Previous numerical approaches to locating the Kerr separatrix were
not always efficient or stable across all of parameter space. In this paper we
show that the Kerr separatrix is the zero set of a single polynomial in
parameter space. This gives two main results. First, we thoroughly analyze
special cases (extreme Kerr, polar orbits, etc.), finding strict bounds on the
limits of roots, and unifying a number of results in the literature. Second, we
pose a stable numerical method which is guaranteed to quickly and robustly
converge to the separatrix. This new approach is implemented in the Black Hole
Perturbation Toolkit, and results in a ~45x speedup over the prior robust
approach.
|
[
{
"created": "Mon, 16 Dec 2019 19:00:00 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Mar 2020 23:13:43 GMT",
"version": "v2"
}
] |
2020-03-09
|
[
[
"Stein",
"Leo C.",
""
],
[
"Warburton",
"Niels",
""
]
] |
Black hole spacetimes, like the Kerr spacetime, admit both stable and plunging orbits, separated in parameter space by the separatrix. Determining the location of the separatrix is of fundamental interest in understanding black holes, and is of crucial importance for modeling extreme mass-ratio inspirals. Previous numerical approaches to locating the Kerr separatrix were not always efficient or stable across all of parameter space. In this paper we show that the Kerr separatrix is the zero set of a single polynomial in parameter space. This gives two main results. First, we thoroughly analyze special cases (extreme Kerr, polar orbits, etc.), finding strict bounds on the limits of roots, and unifying a number of results in the literature. Second, we pose a stable numerical method which is guaranteed to quickly and robustly converge to the separatrix. This new approach is implemented in the Black Hole Perturbation Toolkit, and results in a ~45x speedup over the prior robust approach.
|
1807.01725
|
Lavinia Heisenberg
|
Lavinia Heisenberg
|
A systematic approach to generalisations of General Relativity and their
cosmological implications
|
193 pages, Review under press at Physics Reports
| null |
10.1016/j.physrep.2018.11.006
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A century ago, Einstein formulated his elegant and elaborate theory of
General Relativity, which has so far withstood a multitude of empirical tests
with remarkable success. Notwithstanding the triumphs of Einstein's theory, the
tenacious challenges of modern cosmology and of particle physics have motivated
the exploration of further generalised theories of spacetime. Even though
Einstein's interpretation of gravity in terms of the curvature of spacetime is
commonly adopted, the assignment of geometrical concepts to gravity is
ambiguous because General Relativity allows three entirely different, but
equivalent approaches of which Einstein's interpretation is only one. From a
field-theoretical perspective, however, the construction of a consistent theory
for a Lorentz-invariant massless spin-2 particle uniquely leads to General
Relativity. Keeping Lorentz invariance then implies that any modification of
General Relativity will inevitably introduce additional propagating degrees of
freedom into the gravity sector. Adopting this perspective, we will review the
recent progress in constructing consistent field theories of gravity based on
additional scalar, vector and tensor fields. Within this conceptual framework,
we will discuss theories with Galileons, with Lagrange densities as constructed
by Horndeski and beyond, extended to DHOST interactions, or containing
generalized Proca fields and extensions thereof, or several Proca fields, as
well as bigravity theories and scalar-vector-tensor theories. We will review
the motivation of their inception, different formulations, and essential
results obtained within these classes of theories together with their empirical
viability.
|
[
{
"created": "Wed, 4 Jul 2018 18:03:25 GMT",
"version": "v1"
}
] |
2019-05-01
|
[
[
"Heisenberg",
"Lavinia",
""
]
] |
A century ago, Einstein formulated his elegant and elaborate theory of General Relativity, which has so far withstood a multitude of empirical tests with remarkable success. Notwithstanding the triumphs of Einstein's theory, the tenacious challenges of modern cosmology and of particle physics have motivated the exploration of further generalised theories of spacetime. Even though Einstein's interpretation of gravity in terms of the curvature of spacetime is commonly adopted, the assignment of geometrical concepts to gravity is ambiguous because General Relativity allows three entirely different, but equivalent approaches of which Einstein's interpretation is only one. From a field-theoretical perspective, however, the construction of a consistent theory for a Lorentz-invariant massless spin-2 particle uniquely leads to General Relativity. Keeping Lorentz invariance then implies that any modification of General Relativity will inevitably introduce additional propagating degrees of freedom into the gravity sector. Adopting this perspective, we will review the recent progress in constructing consistent field theories of gravity based on additional scalar, vector and tensor fields. Within this conceptual framework, we will discuss theories with Galileons, with Lagrange densities as constructed by Horndeski and beyond, extended to DHOST interactions, or containing generalized Proca fields and extensions thereof, or several Proca fields, as well as bigravity theories and scalar-vector-tensor theories. We will review the motivation of their inception, different formulations, and essential results obtained within these classes of theories together with their empirical viability.
|
0905.2421
|
Mariam Bouhmadi-Lopez
|
Mariam Bouhmadi-Lopez, Claus Kiefer, Barbara Sandhoefer, Paulo Vargas
Moniz
|
On the quantum fate of singularities in a dark-energy dominated universe
|
20 pages, 6 figures, RevTeX 4. References added. Version to appear in
PRD
|
Phys.Rev.D79:124035,2009
|
10.1103/PhysRevD.79.124035
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Classical models for dark energy can exhibit a variety of singularities, many
of which occur for scale factors much bigger than the Planck length. We address
here the issue whether some of these singularities, the big freeze and the big
demarrage, can be avoided in quantum cosmology. We use the framework of quantum
geometrodynamics. We restrict our attention to a class of models whose matter
content can be described by a generalized Chaplygin gas and be represented by a
scalar field with an appropriate potential. Employing the DeWitt criterium that
the wave function be zero at the classical singularity, we show that a class of
solutions to the Wheeler-DeWitt equation fulfilling this condition can be
found. These solutions thus avoid the classical singularity. We discuss the
reasons for the remaining ambiguity in fixing the solution.
|
[
{
"created": "Thu, 14 May 2009 20:35:43 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Jun 2009 20:10:21 GMT",
"version": "v2"
}
] |
2009-07-09
|
[
[
"Bouhmadi-Lopez",
"Mariam",
""
],
[
"Kiefer",
"Claus",
""
],
[
"Sandhoefer",
"Barbara",
""
],
[
"Moniz",
"Paulo Vargas",
""
]
] |
Classical models for dark energy can exhibit a variety of singularities, many of which occur for scale factors much bigger than the Planck length. We address here the issue whether some of these singularities, the big freeze and the big demarrage, can be avoided in quantum cosmology. We use the framework of quantum geometrodynamics. We restrict our attention to a class of models whose matter content can be described by a generalized Chaplygin gas and be represented by a scalar field with an appropriate potential. Employing the DeWitt criterium that the wave function be zero at the classical singularity, we show that a class of solutions to the Wheeler-DeWitt equation fulfilling this condition can be found. These solutions thus avoid the classical singularity. We discuss the reasons for the remaining ambiguity in fixing the solution.
|
1708.08868
|
Marina Martinez
|
Roberto Emparan, Marina Martinez, Miguel Zilhao
|
Black hole fusion in the extreme mass ratio limit
|
36 pages, 18 figures
|
Phys. Rev. D 97, 044004 (2018)
|
10.1103/PhysRevD.97.044004
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present a simple, general, and accurate construction of the event horizons
for the fusion of two neutral, rotating black holes with arbitrary orientation
and values of their spins, in the extreme mass ratio limit where one black hole
is much larger than the other. We compute several parameters that characterize
the fusion and investigate their dependence on the black hole spin and
orientation axis. We also exhibit and study the appearance of transient
toroidal topology of the horizon. An earlier conjecture about universal
critical exponents before and after an axisymmetric pinch is proven.
|
[
{
"created": "Tue, 29 Aug 2017 16:38:36 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Feb 2018 17:12:07 GMT",
"version": "v2"
}
] |
2018-02-07
|
[
[
"Emparan",
"Roberto",
""
],
[
"Martinez",
"Marina",
""
],
[
"Zilhao",
"Miguel",
""
]
] |
We present a simple, general, and accurate construction of the event horizons for the fusion of two neutral, rotating black holes with arbitrary orientation and values of their spins, in the extreme mass ratio limit where one black hole is much larger than the other. We compute several parameters that characterize the fusion and investigate their dependence on the black hole spin and orientation axis. We also exhibit and study the appearance of transient toroidal topology of the horizon. An earlier conjecture about universal critical exponents before and after an axisymmetric pinch is proven.
|
0806.2507
|
Supratik Pal Dr
|
Sudipta Mukherji, Supratik Pal
|
Bouncing Braneworld with Born-Infeld and Gauss-Bonnet
|
13 pages, 4 figures. Minor revisions. To appear in Mod.Phys.Lett.A
|
Mod.Phys.Lett.A25:35-45,2010
|
10.1142/S0217732310031397
| null |
gr-qc astro-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We show the existence of some bouncing cosmological solutions in the
braneworld scenario. More specifically, we consider a dynamical three-brane in
the background of Born-Infeld and electrically charged Gauss-Bonnet black hole.
We find that, in certain range of parameter space, the brane universe, at least
classically, never shrinks to a zero size, resulting in a singularity-free
cosmology within the classical domain.
|
[
{
"created": "Mon, 16 Jun 2008 06:52:54 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Jun 2009 06:19:46 GMT",
"version": "v2"
}
] |
2010-02-02
|
[
[
"Mukherji",
"Sudipta",
""
],
[
"Pal",
"Supratik",
""
]
] |
We show the existence of some bouncing cosmological solutions in the braneworld scenario. More specifically, we consider a dynamical three-brane in the background of Born-Infeld and electrically charged Gauss-Bonnet black hole. We find that, in certain range of parameter space, the brane universe, at least classically, never shrinks to a zero size, resulting in a singularity-free cosmology within the classical domain.
|
gr-qc/9802059
|
Pablo Laguna
|
Nils Andersson, Pablo Laguna and Philippos Papadopoulos
|
Dynamics of scalar fields in the background of rotating black holes II:
A note on superradiance
|
5 pages, 3 Postscript figures, Submitted Phys. Rev. D
|
Phys.Rev.D58:087503,1998
|
10.1103/PhysRevD.58.087503
|
CGPG 98/2-3
|
gr-qc
| null |
We analyze the amplification due to so-called superradiance from the
scattering of pulses off rotating black holes as a numerical time evolution
problem. We consider the "worst possible case" of scalar field pulses for which
superradiance effects yield amplifications $< 1%$. We show that this small
effect can be isolated by numerically evolving quasi-monochromatic, modulated
pulses with a recently developed Teukolsky code. The results show that it is
possible to study superradiance in the time domain, but only if the initial
data is carefully tuned. This illustrates the intrinsic difficulties of
detecting superradiance in more general evolution scenarios.
|
[
{
"created": "Mon, 23 Feb 1998 17:31:15 GMT",
"version": "v1"
}
] |
2010-11-19
|
[
[
"Andersson",
"Nils",
""
],
[
"Laguna",
"Pablo",
""
],
[
"Papadopoulos",
"Philippos",
""
]
] |
We analyze the amplification due to so-called superradiance from the scattering of pulses off rotating black holes as a numerical time evolution problem. We consider the "worst possible case" of scalar field pulses for which superradiance effects yield amplifications $< 1%$. We show that this small effect can be isolated by numerically evolving quasi-monochromatic, modulated pulses with a recently developed Teukolsky code. The results show that it is possible to study superradiance in the time domain, but only if the initial data is carefully tuned. This illustrates the intrinsic difficulties of detecting superradiance in more general evolution scenarios.
|
1602.06400
|
Christian Klein
|
S. Bai, G. Izquierdo, and C. Klein
|
Numerical study of the Kerr solution in rotating coordinates
| null |
Phys. Rev. D 93, 124001 (2016)
|
10.1103/PhysRevD.93.124001
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Kerr solution in coordinates corotating with the horizon is studied as a
testbed for a spacetime with a helical Killing vector in the Ernst picture. The
solution is numerically constructed by solving the Ernst equation with a
spectral method and a Newton iteration. We discuss convergence of the iteration
for several initial iterates and different values of the Kerr parameters.
|
[
{
"created": "Sat, 20 Feb 2016 12:42:16 GMT",
"version": "v1"
}
] |
2016-06-08
|
[
[
"Bai",
"S.",
""
],
[
"Izquierdo",
"G.",
""
],
[
"Klein",
"C.",
""
]
] |
The Kerr solution in coordinates corotating with the horizon is studied as a testbed for a spacetime with a helical Killing vector in the Ernst picture. The solution is numerically constructed by solving the Ernst equation with a spectral method and a Newton iteration. We discuss convergence of the iteration for several initial iterates and different values of the Kerr parameters.
|
2402.08240
|
Tao Zhu
|
Bo-Yang Zhang, Tao Zhu, Jing-Fei Zhang, and Xin Zhang
|
Forecasts for Constraining Lorentz-violating Damping of Gravitational
Waves from Compact Binary Inspirals
|
14 pages; v2: to appear in PRD
| null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
Violation of Lorentz symmetry can result in two distinct effects in the
propagation of the gravitational waves (GWs). One is a modified dispersion
relation and another is a frequency-dependent damping of GWs. While the former
has been extensively studied in the literature, in this paper we concentrate on
the frequency-dependent damping effect that arises from several specific
Lorentz-violating theories, such as spatial covariant gravities,
Ho\v{r}ava-Lifshitz gravities, etc. This Lorentz-violating damping effect
changes the damping rate of GWs at different frequencies and leads to an
amplitude correction to the GW waveform of compact binary inspiral systems.
With this modified waveform, we then use the Fisher information matrix to
investigate the prospects of constraining the Lorentz-violating damping effect
with GW observations. We consider both ground-based and space-based GW
detectors, including the advanced LIGO, Einstein Telescope, Cosmic Explorer
(CE), Taiji, TianQin, and LISA. Our results indicate that the ground-based
detectors in general give tighter constraints than those from the space-based
detectors. Among the considered three ground-based detectors, CE can give the
tightest constraints on the Lorentz-violating damping effect, which improves
the current constraint from LIGO-Virgo-KAGRA events by about 8 times.
|
[
{
"created": "Tue, 13 Feb 2024 06:09:48 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Apr 2024 06:35:10 GMT",
"version": "v2"
}
] |
2024-04-11
|
[
[
"Zhang",
"Bo-Yang",
""
],
[
"Zhu",
"Tao",
""
],
[
"Zhang",
"Jing-Fei",
""
],
[
"Zhang",
"Xin",
""
]
] |
Violation of Lorentz symmetry can result in two distinct effects in the propagation of the gravitational waves (GWs). One is a modified dispersion relation and another is a frequency-dependent damping of GWs. While the former has been extensively studied in the literature, in this paper we concentrate on the frequency-dependent damping effect that arises from several specific Lorentz-violating theories, such as spatial covariant gravities, Ho\v{r}ava-Lifshitz gravities, etc. This Lorentz-violating damping effect changes the damping rate of GWs at different frequencies and leads to an amplitude correction to the GW waveform of compact binary inspiral systems. With this modified waveform, we then use the Fisher information matrix to investigate the prospects of constraining the Lorentz-violating damping effect with GW observations. We consider both ground-based and space-based GW detectors, including the advanced LIGO, Einstein Telescope, Cosmic Explorer (CE), Taiji, TianQin, and LISA. Our results indicate that the ground-based detectors in general give tighter constraints than those from the space-based detectors. Among the considered three ground-based detectors, CE can give the tightest constraints on the Lorentz-violating damping effect, which improves the current constraint from LIGO-Virgo-KAGRA events by about 8 times.
|
2404.09795
|
Predrag Jovanovic
|
Predrag Jovanovi\'c, Vesna Borka Jovanovi\'c, Du\v{s}ko Borka,
Alexander F. Zakharov
|
Constraints on graviton mass from Schwarzschild precession in the orbits
of S-stars around the Galactic Center
|
16 pages, 4 tables, 3 figures. Accepted for publication in Symmetry
| null | null | null |
gr-qc astro-ph.GA
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we use a modification of the Newtonian gravitational potential
with a non-linear Yukawa-like correction, as it was proposed by C. Will earlier
to obtain new bounds on graviton mass from the observed orbits of S-stars
around the Galactic Center (GC). This phenomenological potential differs from
the gravitational potential obtained in the weak field limit of Yukawa gravity,
which we used in our previous studies. We also assumed that the orbital
precession of S-stars is close to the prediction of General Relativity (GR) for
Schwarzschild precession, but with a possible small discrepancy from it. This
assumption is motivated by the fact that the GRAVITY Collaboration in 2020 and
in 2022 detected Schwarzschild precession in the S2 star orbit around the
Supermassive Black Hole (SMBH) at the GC. Using this approach, we were able to
constrain parameter $\lambda$ of the potential and, assuming that it represents
the graviton Compton wavelength, we also found the corresponding upper bound of
graviton mass. The obtained results were then compared with our previous
estimates, as well as with the estimates of other authors.
|
[
{
"created": "Mon, 15 Apr 2024 13:52:20 GMT",
"version": "v1"
}
] |
2024-04-16
|
[
[
"Jovanović",
"Predrag",
""
],
[
"Jovanović",
"Vesna Borka",
""
],
[
"Borka",
"Duško",
""
],
[
"Zakharov",
"Alexander F.",
""
]
] |
In this paper we use a modification of the Newtonian gravitational potential with a non-linear Yukawa-like correction, as it was proposed by C. Will earlier to obtain new bounds on graviton mass from the observed orbits of S-stars around the Galactic Center (GC). This phenomenological potential differs from the gravitational potential obtained in the weak field limit of Yukawa gravity, which we used in our previous studies. We also assumed that the orbital precession of S-stars is close to the prediction of General Relativity (GR) for Schwarzschild precession, but with a possible small discrepancy from it. This assumption is motivated by the fact that the GRAVITY Collaboration in 2020 and in 2022 detected Schwarzschild precession in the S2 star orbit around the Supermassive Black Hole (SMBH) at the GC. Using this approach, we were able to constrain parameter $\lambda$ of the potential and, assuming that it represents the graviton Compton wavelength, we also found the corresponding upper bound of graviton mass. The obtained results were then compared with our previous estimates, as well as with the estimates of other authors.
|
1905.10380
|
Andrew R. Liddle
|
Stephon Alexander, Marina Cort\^es, Andrew R. Liddle, Jo\~ao Magueijo,
Robert Sims, and Lee Smolin
|
A Zero-Parameter Extension of General Relativity with Varying
Cosmological Constant
|
Companion paper to arXiv:1905.10382. Minor updates to match published
version
|
Phys. Rev. D 100, 083506 (2019)
|
10.1103/PhysRevD.100.083506
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We provide a new extension of general relativity (GR) which has the
remarkable property of being more constrained than GR plus a cosmological
constant, having one less free parameter. This is implemented by allowing the
cosmological constant to have a consistent space-time variation, through coding
its dynamics in the torsion tensor. We demonstrate this mechanism by adding a
`quasi-topological' term to the Einstein action, which naturally realizes a
dynamical torsion with an automatic satisfaction of the Bianchi identities.
Moreover, variation of the action with respect to this dynamical $\Lambda$
fixes it in terms of other variables, thus providing a scenario with less
freedom than general relativity with a cosmological constant. Once matter is
introduced, at least in the homogeneous and isotropic reduction, $\Lambda$ is
uniquely determined by the field content of the model. We make an explicit
construction using the Palatini formulation of GR and describe the striking
properties of this new theory. We also highlight some possible extensions to
the theory. A companion paper [1] explores the Friedmann--Robertson--Walker
reduction for cosmology, and future work will study Solar System tests of the
theory.
|
[
{
"created": "Fri, 24 May 2019 18:00:04 GMT",
"version": "v1"
},
{
"created": "Wed, 31 Jul 2019 14:24:36 GMT",
"version": "v2"
},
{
"created": "Fri, 4 Oct 2019 16:17:32 GMT",
"version": "v3"
}
] |
2019-10-09
|
[
[
"Alexander",
"Stephon",
""
],
[
"Cortês",
"Marina",
""
],
[
"Liddle",
"Andrew R.",
""
],
[
"Magueijo",
"João",
""
],
[
"Sims",
"Robert",
""
],
[
"Smolin",
"Lee",
""
]
] |
We provide a new extension of general relativity (GR) which has the remarkable property of being more constrained than GR plus a cosmological constant, having one less free parameter. This is implemented by allowing the cosmological constant to have a consistent space-time variation, through coding its dynamics in the torsion tensor. We demonstrate this mechanism by adding a `quasi-topological' term to the Einstein action, which naturally realizes a dynamical torsion with an automatic satisfaction of the Bianchi identities. Moreover, variation of the action with respect to this dynamical $\Lambda$ fixes it in terms of other variables, thus providing a scenario with less freedom than general relativity with a cosmological constant. Once matter is introduced, at least in the homogeneous and isotropic reduction, $\Lambda$ is uniquely determined by the field content of the model. We make an explicit construction using the Palatini formulation of GR and describe the striking properties of this new theory. We also highlight some possible extensions to the theory. A companion paper [1] explores the Friedmann--Robertson--Walker reduction for cosmology, and future work will study Solar System tests of the theory.
|
2102.08948
|
Sarbari Guha Dr.
|
Sarbari Guha and Uttaran Ghosh
|
Dynamical conditions and causal transport of dissipative spherical
collapse in $f(R,T)$ gravity
|
22 pages, accepted for publication in EPJP
|
European Physical Journal Plus, 2021
|
10.1140/epjp/s13360-021-01446-4
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
In this paper, we have investigated the non-adiabatic spherical gravitational
collapse in the framework of the $f(R,T)$ theory of gravity with a locally
anisotropic fluid that undergoes dissipation in the form of heat flux,
free-streaming radiation, and shearing viscosity. The dynamical equations are
analyzed in detail, both in the Newtonian and post-Newtonian regimes. Finally
we couple the dynamical equations to the full causal transport equation in the
context of Israel-Stewart theory of dissipative systems. This yields us a
better understanding of the collapse dynamics and may be connected to various
astrophysical consequences.
|
[
{
"created": "Tue, 16 Feb 2021 19:45:57 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Apr 2021 18:49:51 GMT",
"version": "v2"
}
] |
2021-06-08
|
[
[
"Guha",
"Sarbari",
""
],
[
"Ghosh",
"Uttaran",
""
]
] |
In this paper, we have investigated the non-adiabatic spherical gravitational collapse in the framework of the $f(R,T)$ theory of gravity with a locally anisotropic fluid that undergoes dissipation in the form of heat flux, free-streaming radiation, and shearing viscosity. The dynamical equations are analyzed in detail, both in the Newtonian and post-Newtonian regimes. Finally we couple the dynamical equations to the full causal transport equation in the context of Israel-Stewart theory of dissipative systems. This yields us a better understanding of the collapse dynamics and may be connected to various astrophysical consequences.
|
2207.11856
|
Marcell Howard
|
Stephon Alexander, Tatsuya Daniel, Marcell Howard, Morgane Konig
|
An Exact Fermionic Chern-Simons-Kodama State in Quantum Gravity
| null |
Phys. Rev. D 106, 10612 (2022)
|
10.1103/PhysRevD.106.106012
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Chern-Simons-Kodama (CSK) state is an exact, non-perturbative wave
function in the Ashtekar formulation of classical General Relativity. In this
work, we find a generalized fermionic CSK state by solving the extended
gravitational and fermionic Hamiltonian constraints of the Wheeler-DeWitt
equation exactly. We show that this new state reduces to the original Kodama
state upon symmetry reduction to FRW coordinates with perturbative fermionic
corrections, making contact with the Hartle-Hawking and Vilenkin wave functions
of the universe in cosmology. We also find that when both torsion and fermions
are non-vanishing, the wave function possesses a finite amplitude to evade the
Big Bang curvature singularity.
|
[
{
"created": "Mon, 25 Jul 2022 00:36:35 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Aug 2022 17:24:04 GMT",
"version": "v2"
}
] |
2022-11-21
|
[
[
"Alexander",
"Stephon",
""
],
[
"Daniel",
"Tatsuya",
""
],
[
"Howard",
"Marcell",
""
],
[
"Konig",
"Morgane",
""
]
] |
The Chern-Simons-Kodama (CSK) state is an exact, non-perturbative wave function in the Ashtekar formulation of classical General Relativity. In this work, we find a generalized fermionic CSK state by solving the extended gravitational and fermionic Hamiltonian constraints of the Wheeler-DeWitt equation exactly. We show that this new state reduces to the original Kodama state upon symmetry reduction to FRW coordinates with perturbative fermionic corrections, making contact with the Hartle-Hawking and Vilenkin wave functions of the universe in cosmology. We also find that when both torsion and fermions are non-vanishing, the wave function possesses a finite amplitude to evade the Big Bang curvature singularity.
|
1503.08891
|
Morgan Lynch
|
Morgan H. Lynch
|
Accelerated Quantum Dynamics
|
24 pages, 7 figures. Accepted for publication in Phys. Rev. D
|
Phys. Rev. D 92, 024019 (2015)
| null | null |
gr-qc hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we establish a formalism for the computation of observables due
to acceleration-induced particle physics processes. General expressions for the
transition rate, multiplicity, power, spectra, and displacement law of
particles undergoing time-dependent acceleration and transitioning into a final
state of arbitrary particle number are obtained. The transition rate, power,
and spectra are characterized by unique polynomials of multiplicity and thermal
distributions of both bosonic and fermionic statistics. The
acceleration-dependent multiplicities are computed in terms of the branching
fractions of the associated inertial processes. The displacement law of the
spectra predicts that the energy of the emitted particles is directly
proportional to the accelerated temperature.
|
[
{
"created": "Tue, 31 Mar 2015 02:42:27 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Jun 2015 14:39:07 GMT",
"version": "v2"
},
{
"created": "Tue, 14 Jul 2015 21:21:51 GMT",
"version": "v3"
}
] |
2015-07-16
|
[
[
"Lynch",
"Morgan H.",
""
]
] |
In this paper we establish a formalism for the computation of observables due to acceleration-induced particle physics processes. General expressions for the transition rate, multiplicity, power, spectra, and displacement law of particles undergoing time-dependent acceleration and transitioning into a final state of arbitrary particle number are obtained. The transition rate, power, and spectra are characterized by unique polynomials of multiplicity and thermal distributions of both bosonic and fermionic statistics. The acceleration-dependent multiplicities are computed in terms of the branching fractions of the associated inertial processes. The displacement law of the spectra predicts that the energy of the emitted particles is directly proportional to the accelerated temperature.
|
1105.6249
|
Rainer Verch
|
Rainer Verch
|
Local covariance, renormalization ambiguity, and local thermal
equilibrium in cosmology
|
28 p, 2 figures. To appear in the proceedings of the conference
"Quantum Field Theory and Gravity" (Regensburg, Germany, Sep 28 - Oct 1,
2010), F. Finster et al. (eds.) (Birkhaeuser, Basel, 2011). v2: References
updated and layout snags removed
| null | null | null |
gr-qc hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This article reviews some aspects of local covariance and of the ambiguities
and anomalies involved in the definition of the stress energy tensor of quantum
field theory in curved spacetime. Then, a summary is given of the approach
proposed by Buchholz et al. to define local thermal equilibrium states in
quantum field theory, i.e., non-equilibrium states to which, locally, one can
assign thermal parameters, such as temperature or thermal stress-energy. The
extension of that concept to curved spacetime is discussed and some related
results are presented. Finally, the recent approach to cosmology by Dappiaggi,
Fredenhagen and Pinamonti, based on a distinguished fixing of the stress-energy
renormalization ambiguity in the setting of the semiclassical Einstein
equations, is briefly described. The concept of local thermal equilibrium
states is then applied, to yield the result that the temperature behaviour of a
quantized, massless, conformally coupled linear scalar field at early
cosmological times is more singular than that of classical radiation.
|
[
{
"created": "Tue, 31 May 2011 12:02:17 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Jun 2011 17:17:00 GMT",
"version": "v2"
}
] |
2011-06-07
|
[
[
"Verch",
"Rainer",
""
]
] |
This article reviews some aspects of local covariance and of the ambiguities and anomalies involved in the definition of the stress energy tensor of quantum field theory in curved spacetime. Then, a summary is given of the approach proposed by Buchholz et al. to define local thermal equilibrium states in quantum field theory, i.e., non-equilibrium states to which, locally, one can assign thermal parameters, such as temperature or thermal stress-energy. The extension of that concept to curved spacetime is discussed and some related results are presented. Finally, the recent approach to cosmology by Dappiaggi, Fredenhagen and Pinamonti, based on a distinguished fixing of the stress-energy renormalization ambiguity in the setting of the semiclassical Einstein equations, is briefly described. The concept of local thermal equilibrium states is then applied, to yield the result that the temperature behaviour of a quantized, massless, conformally coupled linear scalar field at early cosmological times is more singular than that of classical radiation.
|
1703.04748
|
Marc Geiller
|
Marc Geiller
|
Edge modes and corner ambiguities in 3d Chern-Simons theory and gravity
|
Published version
|
Nucl. Phys. B924C (2017) 312-365
|
10.1016/j.nuclphysb.2017.09.010
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Boundaries in gauge field theories are known to be the locus of a wealth of
interesting phenomena, as illustrated for example by the holographic principle
or by the AdS/CFT and bulk-boundary correspondences. In particular, it has been
acknowledged for quite some time that boundaries can break gauge invariance,
and thereby turn gauge degrees of freedom into physical ones. There is however
no known systematic way of identifying these degrees of freedom and possible
associated boundary observables. Following recent work by Donnelly and Freidel,
we show that this can be achieved by extending the covariant Hamiltonian
formalism so as to make it gauge-invariant under arbitrary large gauge
transformations. This can be done at the expense of extending the phase space
by introducing new boundary fields, which in turn determine new boundary
symmetries and observables. We present the general framework behind this
construction, and find the conditions under which it can be applied to an
arbitrary Lagrangian. By studying the examples of Abelian Chern-Simons theory
and first order three-dimensional gravity, we then show that the new boundary
observables satisfy the known corresponding Kac-Moody affine algebras. This
shows that this new extended phase space formulation does indeed properly
describe the dynamical boundary degrees of freedom, and gives credit to the
results which have been previously derived in the case of diffeomorphism
symmetry. We expect that this systematic understanding of the boundary
symmetries will play a major role for the quantization of gravity in finite
regions.
|
[
{
"created": "Tue, 14 Mar 2017 22:09:48 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Apr 2017 21:04:27 GMT",
"version": "v2"
},
{
"created": "Tue, 2 May 2017 20:57:43 GMT",
"version": "v3"
},
{
"created": "Sun, 28 May 2017 17:25:56 GMT",
"version": "v4"
},
{
"created": "Tue, 26 Sep 2017 00:49:13 GMT",
"version": "v5"
}
] |
2017-09-28
|
[
[
"Geiller",
"Marc",
""
]
] |
Boundaries in gauge field theories are known to be the locus of a wealth of interesting phenomena, as illustrated for example by the holographic principle or by the AdS/CFT and bulk-boundary correspondences. In particular, it has been acknowledged for quite some time that boundaries can break gauge invariance, and thereby turn gauge degrees of freedom into physical ones. There is however no known systematic way of identifying these degrees of freedom and possible associated boundary observables. Following recent work by Donnelly and Freidel, we show that this can be achieved by extending the covariant Hamiltonian formalism so as to make it gauge-invariant under arbitrary large gauge transformations. This can be done at the expense of extending the phase space by introducing new boundary fields, which in turn determine new boundary symmetries and observables. We present the general framework behind this construction, and find the conditions under which it can be applied to an arbitrary Lagrangian. By studying the examples of Abelian Chern-Simons theory and first order three-dimensional gravity, we then show that the new boundary observables satisfy the known corresponding Kac-Moody affine algebras. This shows that this new extended phase space formulation does indeed properly describe the dynamical boundary degrees of freedom, and gives credit to the results which have been previously derived in the case of diffeomorphism symmetry. We expect that this systematic understanding of the boundary symmetries will play a major role for the quantization of gravity in finite regions.
|
1311.2489
|
Henriette Elvang
|
Henriette Elvang and Gary T. Horowitz
|
Quantum gravity via supersymmetry and holography
|
58 pages, 8 figures. v2: Minor revisions and clarifications.
References added. v3. References added
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We review the approach to quantum gravity based on supersymmetry, strings,
and holography. This includes a survey of black holes in higher-dimensions,
supersymmetry and supergravity, as well as string theory, black hole
microstates, and the gauge/gravity duality. This presentation will appear as a
chapter in "General Relativity and Gravitation: A Centennial Perspective", to
be published by Cambridge University Press.
|
[
{
"created": "Mon, 11 Nov 2013 16:40:03 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Mar 2014 17:11:45 GMT",
"version": "v2"
},
{
"created": "Wed, 28 May 2014 15:30:15 GMT",
"version": "v3"
}
] |
2014-05-29
|
[
[
"Elvang",
"Henriette",
""
],
[
"Horowitz",
"Gary T.",
""
]
] |
We review the approach to quantum gravity based on supersymmetry, strings, and holography. This includes a survey of black holes in higher-dimensions, supersymmetry and supergravity, as well as string theory, black hole microstates, and the gauge/gravity duality. This presentation will appear as a chapter in "General Relativity and Gravitation: A Centennial Perspective", to be published by Cambridge University Press.
|
1409.3546
|
Guillaume Faye
|
Guillaume Faye, Luc Blanchet, Bala R. Iyer
|
Non-linear multipole interactions and gravitational-wave octupole modes
for inspiralling compact binaries to third-and-a-half post-Newtonian order
|
37 pages, no figure; minor corrections
|
Class. Quantum Grav. 32 (2015) 045016
|
10.1088/0264-9381/32/4/045016
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This paper is motivated by the need to improve the post-Newtonian (PN)
amplitude accuracy of waveforms for gravitational waves generated by
inspiralling compact binaries, both for use in data analysis and in the
comparison between post-Newtonian approximations and numerical relativity
computations. It presents: (i) the non-linear couplings between multipole
moments of general post-Newtonian matter sources up to order 3.5PN, including
all contributions from tails, tails-of-tails and the non-linear memory effect;
and (ii) the source mass-type octupole moment of (non-spinning) compact
binaries up to order 3PN, which permits to complete the expressions of the
octupole modes (3,3) and (3,1) of the gravitational waveform to order 3.5PN. At
this occasion we reconfirm by means of independent calculations our earlier
results concerning the source mass-type quadrupole moment to order 3PN. Related
discussions on factorized resummed waveforms and the occurence of logarithmic
contributions to high order are also included.
|
[
{
"created": "Thu, 11 Sep 2014 19:13:25 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Feb 2015 20:41:39 GMT",
"version": "v2"
}
] |
2015-06-22
|
[
[
"Faye",
"Guillaume",
""
],
[
"Blanchet",
"Luc",
""
],
[
"Iyer",
"Bala R.",
""
]
] |
This paper is motivated by the need to improve the post-Newtonian (PN) amplitude accuracy of waveforms for gravitational waves generated by inspiralling compact binaries, both for use in data analysis and in the comparison between post-Newtonian approximations and numerical relativity computations. It presents: (i) the non-linear couplings between multipole moments of general post-Newtonian matter sources up to order 3.5PN, including all contributions from tails, tails-of-tails and the non-linear memory effect; and (ii) the source mass-type octupole moment of (non-spinning) compact binaries up to order 3PN, which permits to complete the expressions of the octupole modes (3,3) and (3,1) of the gravitational waveform to order 3.5PN. At this occasion we reconfirm by means of independent calculations our earlier results concerning the source mass-type quadrupole moment to order 3PN. Related discussions on factorized resummed waveforms and the occurence of logarithmic contributions to high order are also included.
|
1708.09430
|
Benito A. Ju\'arez-Aubry
|
Benito A. Ju\'arez-Aubry
|
Asymptotics in the time-dependent Hawking and Unruh effects
|
Thesis submitted to the University of Nottingham for the Degree of
Doctor of Philosophy. Thesis supervisor: Dr. Jorma Louko. 230 pages. 20
figures
| null | null | null |
gr-qc hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this thesis, we study the Hawking and Unruh effects in time-dependent
situations, as registered by localised spacetimes observers in several
asymptotic situations.
(Full abstract inside document.)
|
[
{
"created": "Wed, 30 Aug 2017 19:05:25 GMT",
"version": "v1"
}
] |
2017-09-01
|
[
[
"Juárez-Aubry",
"Benito A.",
""
]
] |
In this thesis, we study the Hawking and Unruh effects in time-dependent situations, as registered by localised spacetimes observers in several asymptotic situations. (Full abstract inside document.)
|
2311.17130
|
John W. Moffat
|
John W. Moffat
|
Wide Binaries and Modified Gravity (MOG)
|
7 pages, no figures. arXiv admin note: text overlap with
arXiv:2006.12550 typos and text changes
|
Journal of Cosmology and Astroparticle Physics, JCAP05(2024)079
| null | null |
gr-qc astro-ph.SR
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Wide binary stars are used to test the modified gravity called
Scalar-Tensor-Vector Gravity or MOG. This theory is based on the additional
gravitational degrees of freedom, the scalar field $G=G_N(1+\alpha)$, where
$G_N$ is Newton's constant, and the massive (spin-1 graviton) vector field
$\phi_\mu$. The wide binaries have separations of 2-30 kAU. The MOG
acceleration law, derived from the MOG field equations and equations of motion
of a massive test particle for weak gravitational fields, depends on the
enhanced gravitational constant $G=G_N(1+\alpha)$ and the effective running
mass $\mu$. The magnitude of $\alpha$ depends on the physical length scale or
averaging scale $\ell$ of the system. The modified MOG acceleration law for
weak gravitational fields predicts that for the solar system and for the wide
binary star systems gravitational dynamics follows Newton's law.
|
[
{
"created": "Tue, 28 Nov 2023 17:20:36 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Apr 2024 20:15:24 GMT",
"version": "v2"
},
{
"created": "Wed, 29 May 2024 21:47:05 GMT",
"version": "v3"
}
] |
2024-05-31
|
[
[
"Moffat",
"John W.",
""
]
] |
Wide binary stars are used to test the modified gravity called Scalar-Tensor-Vector Gravity or MOG. This theory is based on the additional gravitational degrees of freedom, the scalar field $G=G_N(1+\alpha)$, where $G_N$ is Newton's constant, and the massive (spin-1 graviton) vector field $\phi_\mu$. The wide binaries have separations of 2-30 kAU. The MOG acceleration law, derived from the MOG field equations and equations of motion of a massive test particle for weak gravitational fields, depends on the enhanced gravitational constant $G=G_N(1+\alpha)$ and the effective running mass $\mu$. The magnitude of $\alpha$ depends on the physical length scale or averaging scale $\ell$ of the system. The modified MOG acceleration law for weak gravitational fields predicts that for the solar system and for the wide binary star systems gravitational dynamics follows Newton's law.
|
1307.0662
|
Jong-Ping Hsu
|
Leonardo Hsu, Jong-Ping Hsu
|
Exact Rotational Space-time Transformations, Davies-Jennison Experiments
and Limiting Lorentz-Poincar\'e Invariance
|
23 pages, to be published in Euro. Phys. J. Plus, vol. 128 (2013)
|
Eur. Phys. J. Plus (2013) 128:74
|
10.1140/epjp/i2013-13074-4
| null |
gr-qc math-ph math.MP physics.optics
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Jennison deduced from the rotational experiments that a rotating radius $r_r$
measured by the rotating observer is contracted by $r_r = r(1-\om^2
r^2/c^2)^{1/2}$, compared with the radius $r$ measured in an inertial frame.
This conclusion differs from the result based on Lorentz transformations. Since
rotational frames are not equivalent to inertial frames, we analyze the
rotational experiments by using the exact rotational space-time transformations
rather than the Lorentz transformations. We derive exact rotational
transformations on the basis of the principle of limiting Lorentz-Poincar\'e
invariance. The exact rotational transformations form a pseudo-group rather
than the usual Lie group. They support Jennison's contraction of a rotating
radius and are consistent with two Davies-Jennison experiments. We also suggest
new experimental tests for the exact rotational transformations.
|
[
{
"created": "Tue, 2 Jul 2013 10:17:27 GMT",
"version": "v1"
}
] |
2014-02-26
|
[
[
"Hsu",
"Leonardo",
""
],
[
"Hsu",
"Jong-Ping",
""
]
] |
Jennison deduced from the rotational experiments that a rotating radius $r_r$ measured by the rotating observer is contracted by $r_r = r(1-\om^2 r^2/c^2)^{1/2}$, compared with the radius $r$ measured in an inertial frame. This conclusion differs from the result based on Lorentz transformations. Since rotational frames are not equivalent to inertial frames, we analyze the rotational experiments by using the exact rotational space-time transformations rather than the Lorentz transformations. We derive exact rotational transformations on the basis of the principle of limiting Lorentz-Poincar\'e invariance. The exact rotational transformations form a pseudo-group rather than the usual Lie group. They support Jennison's contraction of a rotating radius and are consistent with two Davies-Jennison experiments. We also suggest new experimental tests for the exact rotational transformations.
|
1206.6012
|
Ranjan Sharma
|
R. Sharma and R. Tikekar
|
Non-adiabatic radiative collapse of a relativistic star under different
initial conditions
|
To appear in Pramana- j. of physics
|
Pramana -j. of physics, Vol. 79, p. 501, 2012
|
10.1007/s12043-012-0323-4
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We examine the role of space-time geometry in the non-adiabatic collapse of a
star dissipating energy in the form of radial heat flow, studying its evolution
under different initial conditions. The collapse of a star with interior
comprising of a homogeneous perfect fluid is compared with that of a star
filled with inhomogeneous imperfect fluid with anisotropic pressure. Both the
configurations are spherically symmetric, however, in the latter case, the
physical space $t= constant$ of the configurations is assumed to be
inhomogeneous endowed with spheroidal or pseudo-spheroidal geometry. It is
observed that as long as the collapse is shear-free, its evolution depends only
on the mass and size of the star at the onset of collapse.
|
[
{
"created": "Mon, 25 Jun 2012 10:28:43 GMT",
"version": "v1"
}
] |
2013-04-30
|
[
[
"Sharma",
"R.",
""
],
[
"Tikekar",
"R.",
""
]
] |
We examine the role of space-time geometry in the non-adiabatic collapse of a star dissipating energy in the form of radial heat flow, studying its evolution under different initial conditions. The collapse of a star with interior comprising of a homogeneous perfect fluid is compared with that of a star filled with inhomogeneous imperfect fluid with anisotropic pressure. Both the configurations are spherically symmetric, however, in the latter case, the physical space $t= constant$ of the configurations is assumed to be inhomogeneous endowed with spheroidal or pseudo-spheroidal geometry. It is observed that as long as the collapse is shear-free, its evolution depends only on the mass and size of the star at the onset of collapse.
|
gr-qc/9612026
|
Robert Mann
|
S.F.J. Chan and R.B. Mann
|
Scalar Wave Falloff in Asymptotically Anti-de Sitter Backgrounds
|
34 pages, Latex, 26 figures, uses psfig
|
Phys. Rev. D 55, 7546 (1997)
|
10.1103/PhysRevD.55.7546
|
WATPHYS TH-96/20
|
gr-qc
| null |
Conformally invariant scalar waves in black hole spacetimes which are
asymptotically anti-de Sitter are investigated. We consider both the
$(2+1)$-dimensional black hole and $(3+1)$-dimensional Schwarzschild-anti-de
Sitter spacetime as backgrounds. Analytical and numerical methods show that the
waves decay exponentially in the $(2+1)$ dimensional black hole background.
However the falloff pattern of the conformal scalar waves in the
Schwarzschild-anti-de Sitter background is generally neither exponential nor an
inverse power rate, although the approximate falloff of the maximal peak is
weakly exponential. We discuss the implications of these results for mass
inflation.
|
[
{
"created": "Wed, 11 Dec 1996 16:26:22 GMT",
"version": "v1"
}
] |
2016-08-24
|
[
[
"Chan",
"S. F. J.",
""
],
[
"Mann",
"R. B.",
""
]
] |
Conformally invariant scalar waves in black hole spacetimes which are asymptotically anti-de Sitter are investigated. We consider both the $(2+1)$-dimensional black hole and $(3+1)$-dimensional Schwarzschild-anti-de Sitter spacetime as backgrounds. Analytical and numerical methods show that the waves decay exponentially in the $(2+1)$ dimensional black hole background. However the falloff pattern of the conformal scalar waves in the Schwarzschild-anti-de Sitter background is generally neither exponential nor an inverse power rate, although the approximate falloff of the maximal peak is weakly exponential. We discuss the implications of these results for mass inflation.
|
gr-qc/9503003
|
Jean-Guy Demers
|
J.- G. Demers, R. Lafrance and R.C. Myers
|
Black Hole Entropy without Brick Walls
|
15 pages, plain LaTex minor additions including some references;
version accepted for publication
|
Phys.Rev.D52:2245-2253,1995
|
10.1103/PhysRevD.52.2245
|
McGill 95-06
|
gr-qc hep-th
| null |
We present evidence which confirms a suggestion by Susskind and Uglum
regarding black hole entropy. Using a Pauli-Villars regulator, we find that 't
Hooft's approach to evaluating black hole entropy through a
statistical-mechanical counting of states for a scalar field propagating
outside the event horizon yields precisely the one-loop renormalization of the
standard Bekenstein-Hawking formula, $S=\A/(4G)$. Our calculation also yields a
constant contribution to the black hole entropy, a contribution associated with
the one-loop renormalization of higher curvature terms in the gravitational
action.
|
[
{
"created": "Wed, 1 Mar 1995 20:14:12 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Mar 1995 20:25:18 GMT",
"version": "v2"
},
{
"created": "Wed, 21 Jun 1995 01:52:13 GMT",
"version": "v3"
}
] |
2014-11-17
|
[
[
"Demers",
"J. - G.",
""
],
[
"Lafrance",
"R.",
""
],
[
"Myers",
"R. C.",
""
]
] |
We present evidence which confirms a suggestion by Susskind and Uglum regarding black hole entropy. Using a Pauli-Villars regulator, we find that 't Hooft's approach to evaluating black hole entropy through a statistical-mechanical counting of states for a scalar field propagating outside the event horizon yields precisely the one-loop renormalization of the standard Bekenstein-Hawking formula, $S=\A/(4G)$. Our calculation also yields a constant contribution to the black hole entropy, a contribution associated with the one-loop renormalization of higher curvature terms in the gravitational action.
|
1410.4446
|
Behnaz Fazlpour
|
Behnaz Fazlpour, Ali Banijamali
|
Non-minimally Coupled Tachyon Field in Teleparallel Gravity
|
15 pages, 6 figures
| null |
10.1088/1475-7516/2015/04/030
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We perform a full investigation on dynamics of a new dark energy model in
which the four-derivative of a non-canonical scalar field (tachyon) is
non-minimally coupled to the vector torsion. Our analysis is done in the
framework of teleparallel equivalent of general relativity which is based on
torsion instead of curvature. We show that in our model there exists a
late-time scaling attractor (point $P_{4}$), corresponding to an accelerating
universe with the property that dark energy and dark matter densities are of
the same order. Such a point can help to alleviate the cosmological coincidence
problem. Existence of this point is the most significant difference between our
model and another model in which a canonical scalar field (quintessence) is
used instead of tachyon field.
|
[
{
"created": "Thu, 16 Oct 2014 14:27:04 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Feb 2015 21:44:56 GMT",
"version": "v2"
},
{
"created": "Tue, 17 Mar 2015 19:45:44 GMT",
"version": "v3"
}
] |
2015-06-23
|
[
[
"Fazlpour",
"Behnaz",
""
],
[
"Banijamali",
"Ali",
""
]
] |
We perform a full investigation on dynamics of a new dark energy model in which the four-derivative of a non-canonical scalar field (tachyon) is non-minimally coupled to the vector torsion. Our analysis is done in the framework of teleparallel equivalent of general relativity which is based on torsion instead of curvature. We show that in our model there exists a late-time scaling attractor (point $P_{4}$), corresponding to an accelerating universe with the property that dark energy and dark matter densities are of the same order. Such a point can help to alleviate the cosmological coincidence problem. Existence of this point is the most significant difference between our model and another model in which a canonical scalar field (quintessence) is used instead of tachyon field.
|
2205.07642
|
Celio Muniz
|
Marcony S. Cunha, G. Alencar, Celio R. Muniz, Valdir B. Bezerra, and
Hor\'acio S. Vieira
|
Black strings from dark matter
|
16 pages. 9 figures
| null |
10.1016/j.aop.2023.169324
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we obtain two different static black string solutions by
considering as sources axisymmetric dark matter distributions in 3+1
dimensions. These solutions tend asymptotically to the usual static and
uncharged black string vacuum solution predicted by General Relativity (GR). We
show that both the solutions present an event horizon each, like the vacuum
solution, which is larger than the horizon of the latter. Then, we obtain the
Hawking temperature associated with the black string solutions. Differently
from what occurs with the static black string in the vacuum, we find that there
exists a linear density of mass (or tension) remnant associated with a
vanishing Hawking temperature for the obtained solutions. Thus, we analyze how
the presence of dark matter affects the occurrence of the remnants. Further, we
calculate other thermodynamic quantities, namely entropy, heat capacity, and
free energy per length unit, showing that thermal phase transitions can occur
in the presence of dark matter. We also analyze the weak (and null) energy
conditions and conclude that the dark matter does not behave like an exotic
fluid. Finally, we obtain the corresponding stationary solutions, determining
their tensions as functions of both the mass and angular momentum of the black
strings.
|
[
{
"created": "Mon, 16 May 2022 12:56:57 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Apr 2023 14:50:03 GMT",
"version": "v2"
}
] |
2023-05-17
|
[
[
"Cunha",
"Marcony S.",
""
],
[
"Alencar",
"G.",
""
],
[
"Muniz",
"Celio R.",
""
],
[
"Bezerra",
"Valdir B.",
""
],
[
"Vieira",
"Horácio S.",
""
]
] |
In this paper, we obtain two different static black string solutions by considering as sources axisymmetric dark matter distributions in 3+1 dimensions. These solutions tend asymptotically to the usual static and uncharged black string vacuum solution predicted by General Relativity (GR). We show that both the solutions present an event horizon each, like the vacuum solution, which is larger than the horizon of the latter. Then, we obtain the Hawking temperature associated with the black string solutions. Differently from what occurs with the static black string in the vacuum, we find that there exists a linear density of mass (or tension) remnant associated with a vanishing Hawking temperature for the obtained solutions. Thus, we analyze how the presence of dark matter affects the occurrence of the remnants. Further, we calculate other thermodynamic quantities, namely entropy, heat capacity, and free energy per length unit, showing that thermal phase transitions can occur in the presence of dark matter. We also analyze the weak (and null) energy conditions and conclude that the dark matter does not behave like an exotic fluid. Finally, we obtain the corresponding stationary solutions, determining their tensions as functions of both the mass and angular momentum of the black strings.
|
gr-qc/9506034
| null |
M.Alves
|
Quantum Corrections to the Two-dimensional Gravity with External Field
|
12 pages, Latex, revised version
|
Class.Quant.Grav. 13 (1996) 171-178
|
10.1088/0264-9381/13/2/005
| null |
gr-qc hep-th
| null |
We introduce an external field to calculate the quantum corrections of the 2d
gravity, via trace anomaly. We show that there are black hole type solution
even in the absence of matter field and cosmological constant. We also see that
these solutions are similar to the ones obtained from dilaton two-dimensional
gravity.
|
[
{
"created": "Mon, 19 Jun 1995 09:08:58 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Jun 1995 14:18:04 GMT",
"version": "v2"
}
] |
2009-10-28
|
[
[
"Alves",
"M.",
""
]
] |
We introduce an external field to calculate the quantum corrections of the 2d gravity, via trace anomaly. We show that there are black hole type solution even in the absence of matter field and cosmological constant. We also see that these solutions are similar to the ones obtained from dilaton two-dimensional gravity.
|
1408.3008
|
S Habib Mazharimousavi
|
S. Habib Mazharimousavi and M. Halilsoy
|
Global Monopole metric in 2+1-dimensions
|
8 pages, 7 figures published in IJGMMP
|
International Journal of Geometric Methods in Modern Physics, 16,
1950006 (2019)
|
10.1142/S0219887819500063
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In order to obtain the geometry of a global monopole without cosmological
constant and electric charge in $2+1-$ dimensions we make use of the broken $%
O(2)$ symmetry. In the absence of exact solution we determine the series
solutions for both the metric and monopole functions in a consistent manner
that satisfy all equations in appropriate powers. The new expansion elements
are of the form $\frac{1}{r^{n}}\left( \ln r\right) ^{m},$ for the radial
distance $r$ and positive integers $m$ and $n$ constrained by $m\leq n$. To the
lowest order of expansion we find that in analogy with the negative
cosmological constant the geometry of the global monopole acts repulsively,
i.e., in the absence of a cosmological constant the global monopole plays at
large distances the role of a negative cosmological constant.
|
[
{
"created": "Wed, 13 Aug 2014 13:47:54 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Aug 2014 11:08:52 GMT",
"version": "v2"
},
{
"created": "Fri, 10 Oct 2014 08:19:36 GMT",
"version": "v3"
},
{
"created": "Thu, 11 Dec 2014 09:13:48 GMT",
"version": "v4"
},
{
"created": "Thu, 10 Nov 2016 14:21:01 GMT",
"version": "v5"
},
{
"created": "Wed, 16 Jan 2019 12:36:20 GMT",
"version": "v6"
}
] |
2019-01-17
|
[
[
"Mazharimousavi",
"S. Habib",
""
],
[
"Halilsoy",
"M.",
""
]
] |
In order to obtain the geometry of a global monopole without cosmological constant and electric charge in $2+1-$ dimensions we make use of the broken $% O(2)$ symmetry. In the absence of exact solution we determine the series solutions for both the metric and monopole functions in a consistent manner that satisfy all equations in appropriate powers. The new expansion elements are of the form $\frac{1}{r^{n}}\left( \ln r\right) ^{m},$ for the radial distance $r$ and positive integers $m$ and $n$ constrained by $m\leq n$. To the lowest order of expansion we find that in analogy with the negative cosmological constant the geometry of the global monopole acts repulsively, i.e., in the absence of a cosmological constant the global monopole plays at large distances the role of a negative cosmological constant.
|
gr-qc/9412054
| null |
M. Bordag (Institute for Theoretical Physics, Leipzig University) and
A.A. Bytsenko (State Technical University, 195251 St.Petersburg, Russia)
|
Quantum Corrections to the Entropy for Higher Spin Fields in Hyperbolic
Space
|
Revised version -- 1 reference added
|
Grav.Cosmol. 1 (1995) 266-272
| null |
NTZ 23-94
|
gr-qc hep-th
| null |
We calculate the one-loop corrections to the free energy and to the entropy
for fields with arbitrary spins in the space $S^1\otimes H^N$. For conformally
invariant fields by means of a conformal transformation of the metric the
results are valid in Rindler space with $D=N+1$ dimensions. We use the zeta
regularization technique which yields an ultraviolet finite result for the
entropy per unit area. The problem of the infinite area factor in the entropy
which arises equally in Rindler space and in the black hole background is
addressed in the light of a factor space $H^N/\Gamma$.
|
[
{
"created": "Tue, 20 Dec 1994 20:25:07 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Dec 1994 21:09:23 GMT",
"version": "v2"
}
] |
2008-02-03
|
[
[
"Bordag",
"M.",
"",
"Institute for Theoretical Physics, Leipzig University"
],
[
"Bytsenko",
"A. A.",
"",
"State Technical University, 195251 St.Petersburg, Russia"
]
] |
We calculate the one-loop corrections to the free energy and to the entropy for fields with arbitrary spins in the space $S^1\otimes H^N$. For conformally invariant fields by means of a conformal transformation of the metric the results are valid in Rindler space with $D=N+1$ dimensions. We use the zeta regularization technique which yields an ultraviolet finite result for the entropy per unit area. The problem of the infinite area factor in the entropy which arises equally in Rindler space and in the black hole background is addressed in the light of a factor space $H^N/\Gamma$.
|
2403.16942
|
Kaye Jiale Li Ms
|
Kaye Jiale Li, Kinwah Wu, Ziri Younsi, Joana Teixeira, Dinesh Singh
|
Generic gravito-magnetic clock effects
|
11 pages
| null | null | null |
gr-qc astro-ph.HE astro-ph.IM
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
General relativity predicts that two counter-orbiting clocks around a
spinning mass differ in the time required to complete the same orbit. The
difference in these two values for the orbital period is generally referred to
as the gravito-magnetic (GM) clock effect. It has been proposed to measure the
GM clock effect using atomic clocks carried by satellites in prograde and
retrograde orbits around the Earth. The precision and stability required for
satellites to accurately perform this measurement remains a challenge for
current instrumentation. One of the most accurate clocks in the Universe is a
millisecond pulsar, which emits periodic radio pulses with high stability.
Timing of the pulsed signals from millisecond pulsars has proven to be very
successful in testing predictions of general relativity and the GM clock effect
is potentially measurable in binary systems. In this work we derive the generic
GM clock effect by considering a slowly-spinning binary system on an elliptical
orbit, with both arbitrary mass ratio and arbitrary spin orientations. The
spin-orbit interaction introduces a perturbation to the orbit, causing the
orbital plane to precess and nutate. We identify several different
contributions to the clock effects: the choice of spin supplementary condition
and the observer-dependent definition of a full revolution and
"nearly-identical" orbits. We discuss the impact of these subtle definitions on
the formula for GM clock effects and show that most of the existing formulae in
the literature can be recovered under appropriate assumptions.
|
[
{
"created": "Mon, 25 Mar 2024 17:05:12 GMT",
"version": "v1"
}
] |
2024-03-26
|
[
[
"Li",
"Kaye Jiale",
""
],
[
"Wu",
"Kinwah",
""
],
[
"Younsi",
"Ziri",
""
],
[
"Teixeira",
"Joana",
""
],
[
"Singh",
"Dinesh",
""
]
] |
General relativity predicts that two counter-orbiting clocks around a spinning mass differ in the time required to complete the same orbit. The difference in these two values for the orbital period is generally referred to as the gravito-magnetic (GM) clock effect. It has been proposed to measure the GM clock effect using atomic clocks carried by satellites in prograde and retrograde orbits around the Earth. The precision and stability required for satellites to accurately perform this measurement remains a challenge for current instrumentation. One of the most accurate clocks in the Universe is a millisecond pulsar, which emits periodic radio pulses with high stability. Timing of the pulsed signals from millisecond pulsars has proven to be very successful in testing predictions of general relativity and the GM clock effect is potentially measurable in binary systems. In this work we derive the generic GM clock effect by considering a slowly-spinning binary system on an elliptical orbit, with both arbitrary mass ratio and arbitrary spin orientations. The spin-orbit interaction introduces a perturbation to the orbit, causing the orbital plane to precess and nutate. We identify several different contributions to the clock effects: the choice of spin supplementary condition and the observer-dependent definition of a full revolution and "nearly-identical" orbits. We discuss the impact of these subtle definitions on the formula for GM clock effects and show that most of the existing formulae in the literature can be recovered under appropriate assumptions.
|
0804.1029
|
Liselotte De Groote
|
Liselotte De Groote, Norbert Van den Bergh
|
Complete integration of the aligned Newman Tamburino Maxwell solutions
| null | null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the cylindrical class of Newman Tamburino equations in the
presence of an aligned Maxwell field. After obtaining a complete integration of
the field equations we look at the possible vacuum limits and we examine the
symmetries of the general solution.
|
[
{
"created": "Mon, 7 Apr 2008 13:55:58 GMT",
"version": "v1"
}
] |
2008-04-08
|
[
[
"De Groote",
"Liselotte",
""
],
[
"Bergh",
"Norbert Van den",
""
]
] |
We investigate the cylindrical class of Newman Tamburino equations in the presence of an aligned Maxwell field. After obtaining a complete integration of the field equations we look at the possible vacuum limits and we examine the symmetries of the general solution.
|
1807.00765
|
Peter Horvathy
|
P.-M. Zhang, M. Cariglia, C. Duval, M. Elbistan, G. W. Gibbons, P.A.
Horvathy
|
Ion Traps and the Memory Effect for Periodic Gravitational Waves
|
Final version: 32 pages. An error in sec. 6 (Lagrange points) pointed
out for us by Matt Kalinski (to whom we are grateful) is corrected and the
stability problem clarified. See also our Erratum: Phys. Rev. D 98, 089901(E)
(2018). Our paper is dedicated to the memory of our friend and collaborator
Christian Duval, who deceased shortly after our paper was published
|
Phys. Rev. D 98, 044037 (2018)
|
10.1103/PhysRevD.98.044037
| null |
gr-qc astro-ph.CO hep-th physics.class-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Eisenhart lift of a Paul Trap used to store ions in molecular physics is
a linearly polarized periodic gravitational wave. A modified version of
Dehmelt's Penning Trap is in turn related to circularly polarized periodic
gravitational waves, sought for in inflationary models. Similar equations rule
also the Lagrange points in Celestial Mechanics. The explanation is provided by
anisotropic oscillators.
|
[
{
"created": "Mon, 2 Jul 2018 16:04:11 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Jul 2018 00:48:12 GMT",
"version": "v2"
},
{
"created": "Thu, 9 Aug 2018 06:44:13 GMT",
"version": "v3"
},
{
"created": "Mon, 1 Oct 2018 11:59:22 GMT",
"version": "v4"
},
{
"created": "Sun, 14 Oct 2018 08:36:22 GMT",
"version": "v5"
},
{
"created": "Thu, 11 Apr 2019 11:31:30 GMT",
"version": "v6"
}
] |
2019-04-12
|
[
[
"Zhang",
"P. -M.",
""
],
[
"Cariglia",
"M.",
""
],
[
"Duval",
"C.",
""
],
[
"Elbistan",
"M.",
""
],
[
"Gibbons",
"G. W.",
""
],
[
"Horvathy",
"P. A.",
""
]
] |
The Eisenhart lift of a Paul Trap used to store ions in molecular physics is a linearly polarized periodic gravitational wave. A modified version of Dehmelt's Penning Trap is in turn related to circularly polarized periodic gravitational waves, sought for in inflationary models. Similar equations rule also the Lagrange points in Celestial Mechanics. The explanation is provided by anisotropic oscillators.
|
gr-qc/9411061
|
Jemal Guven
|
Riccardo Capovilla and Jemal Guven
|
Large Deformations of Relativistic Membranes: A Generalization of the
Raychaudhuri Equations
|
24 pages, Plain Tex, sign errors corrected, new references added. To
appear in Physical Review D
|
Phys.Rev. D52 (1995) 1072-1081
|
10.1103/PhysRevD.52.1072
| null |
gr-qc
| null |
A coupled system of non-linear partial differential equations is presented
which describes non-perturbatively the evolution of deformations of a
relativistic membrane of arbitrary dimension, $D$, in an arbitrary background
spacetime. These equations can be considered from a formal point of view as
higher dimensional analogs of the Raychaudhuri equations for point particles to
which they are shown to reduce when $D=1$. For $D=1$ or $D=2$ (a string), there
are no constraints on the initial data. If $D>2$, however, there will be
constraints with a corresponding complication of the evolution problem. The
consistent evolution of the constraints is guaranteed by an integrability
condition which is satisfied when the equations of motion are satisfied.
Explicit calculations are performed for membranes described by the Nambu
action.
|
[
{
"created": "Wed, 23 Nov 1994 22:37:29 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Apr 1995 20:10:07 GMT",
"version": "v2"
}
] |
2009-10-22
|
[
[
"Capovilla",
"Riccardo",
""
],
[
"Guven",
"Jemal",
""
]
] |
A coupled system of non-linear partial differential equations is presented which describes non-perturbatively the evolution of deformations of a relativistic membrane of arbitrary dimension, $D$, in an arbitrary background spacetime. These equations can be considered from a formal point of view as higher dimensional analogs of the Raychaudhuri equations for point particles to which they are shown to reduce when $D=1$. For $D=1$ or $D=2$ (a string), there are no constraints on the initial data. If $D>2$, however, there will be constraints with a corresponding complication of the evolution problem. The consistent evolution of the constraints is guaranteed by an integrability condition which is satisfied when the equations of motion are satisfied. Explicit calculations are performed for membranes described by the Nambu action.
|
2102.06517
|
Samuel Kov\'a\v{c}ik
|
Samuel Kov\'a\v{c}ik
|
Hawking-Radiation Recoil of Microscopic Black Holes
|
10 pages, 3 figures
| null | null | null |
gr-qc astro-ph.CO hep-ph
|
http://creativecommons.org/licenses/by/4.0/
|
Hawking radiation would make microscopic black holes evaporate rapidly, which
excludes them from many astrophysical considerations. However, it has been
argued that the quantum nature of space would alter this behaviour: the
temperature of a Planck-size black hole vanishes, and what is left behind is a
Planck-mass remnant with the cross-section of $\approx 10^{-70}\mbox{m}^2$,
which makes a direct observation nearly impossible. Such black hole remnants
have been identified as possible dark matter candidates. Here, we argue that
the final stage of evaporation has a recoil effect that gives them a velocity
up to $\approx 10^{-1} c$. This would lead to a disagreement with the cold dark
matter cosmological model unless the primordial black hole formation ceased
shortly after the inflation era.
|
[
{
"created": "Thu, 11 Feb 2021 11:31:30 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Nov 2021 20:58:02 GMT",
"version": "v2"
}
] |
2021-11-05
|
[
[
"Kováčik",
"Samuel",
""
]
] |
Hawking radiation would make microscopic black holes evaporate rapidly, which excludes them from many astrophysical considerations. However, it has been argued that the quantum nature of space would alter this behaviour: the temperature of a Planck-size black hole vanishes, and what is left behind is a Planck-mass remnant with the cross-section of $\approx 10^{-70}\mbox{m}^2$, which makes a direct observation nearly impossible. Such black hole remnants have been identified as possible dark matter candidates. Here, we argue that the final stage of evaporation has a recoil effect that gives them a velocity up to $\approx 10^{-1} c$. This would lead to a disagreement with the cold dark matter cosmological model unless the primordial black hole formation ceased shortly after the inflation era.
|
2306.17512
|
James Lucietti
|
Maciej Dunajski, James Lucietti
|
Intrinsic rigidity of extremal horizons
|
13 pages
| null | null | null |
gr-qc hep-th math.DG
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We prove that the intrinsic geometry of compact cross-sections of any vacuum
extremal horizon must admit a Killing vector field. If the cross-sections are
two-dimensional spheres, this implies that the most general solution is the
extremal Kerr horizon and completes the classification of the associated
near-horizon geometries. The same results hold with a cosmological constant.
Furthermore, we also deduce that any non-trivial vacuum near-horizon geometry,
with a non-positive cosmological constant, must have an SO(2,1) isometry in all
dimensions under no symmetry assumptions. We also show that, if the
cross-sections are two-dimensional, the horizon Einstein equation is equivalent
to a single fourth order PDE for the K\"ahler potential, and that this equation
is explicitly solvable on the sphere if the corresponding metric admits a
Killing vector.
|
[
{
"created": "Fri, 30 Jun 2023 09:56:34 GMT",
"version": "v1"
}
] |
2023-07-03
|
[
[
"Dunajski",
"Maciej",
""
],
[
"Lucietti",
"James",
""
]
] |
We prove that the intrinsic geometry of compact cross-sections of any vacuum extremal horizon must admit a Killing vector field. If the cross-sections are two-dimensional spheres, this implies that the most general solution is the extremal Kerr horizon and completes the classification of the associated near-horizon geometries. The same results hold with a cosmological constant. Furthermore, we also deduce that any non-trivial vacuum near-horizon geometry, with a non-positive cosmological constant, must have an SO(2,1) isometry in all dimensions under no symmetry assumptions. We also show that, if the cross-sections are two-dimensional, the horizon Einstein equation is equivalent to a single fourth order PDE for the K\"ahler potential, and that this equation is explicitly solvable on the sphere if the corresponding metric admits a Killing vector.
|
2001.00010
|
Gauranga Samanta
|
Nisha Godani and Gauranga C. Samanta
|
Traversable Wormholes in $R+\alpha R^n$ Gravity
|
33 pages, 16 figures, accepted in EPJC
| null |
10.1140/epjc/s10052-019-7587-5
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, the study of traversable wormholes in $f(R)$ gravity with the
function $f(R)=R+\alpha R^n$, where $\alpha$ and $n$ are arbitrary constants,
is taken into account. The shape function $b(r)=\frac{r}{\exp(r-r_0)}$,
proposed by Samanta et al. \cite{godani1}, is considered. The energy conditions
with respect to both constant and variable redshift functions are discussed and
the existence of wormhole solutions without presence of exotic matter is
investigated.
|
[
{
"created": "Mon, 30 Dec 2019 05:01:36 GMT",
"version": "v1"
}
] |
2020-01-29
|
[
[
"Godani",
"Nisha",
""
],
[
"Samanta",
"Gauranga C.",
""
]
] |
In this work, the study of traversable wormholes in $f(R)$ gravity with the function $f(R)=R+\alpha R^n$, where $\alpha$ and $n$ are arbitrary constants, is taken into account. The shape function $b(r)=\frac{r}{\exp(r-r_0)}$, proposed by Samanta et al. \cite{godani1}, is considered. The energy conditions with respect to both constant and variable redshift functions are discussed and the existence of wormhole solutions without presence of exotic matter is investigated.
|
1601.03148
|
Taeyoon Moon
|
Yun Soo Myung and Taeyoon Moon
|
Inflaton decay and reheating in nonminimal derivative coupling
|
1+18 pages, 11 figures, accepted for publication in JCAP
| null |
10.1088/1475-7516/2016/07/014
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the inflaton decay and reheating period after the end of
inflation in the non-minimal derivative coupling (NDC) model with chaotic
potential. In general, this model is known to provide an enhanced slow-roll
inflation caused by gravitationally enhanced friction. We find violent
oscillations of Hubble parameter which induces oscillations of the sound speed
squared, implying the Lagrangian instability of curvature perturbation $\zeta$
under the comoving gauge $\varphi=0$. Also, it is shown that the curvature
perturbation blows up at $\dot{\phi}=0$, leading to the breakdown of the
comoving gauge at $\dot{\phi}=0$. Therefore, we use the Newtonian gauge to
perform the perturbation analysis where the Newtonian potential is employed as
a physical variable. The curvature perturbation is not considered as a physical
variable which describes a relevant perturbation during reheating.
|
[
{
"created": "Wed, 13 Jan 2016 07:20:02 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Jul 2016 03:53:25 GMT",
"version": "v2"
}
] |
2016-07-20
|
[
[
"Myung",
"Yun Soo",
""
],
[
"Moon",
"Taeyoon",
""
]
] |
We investigate the inflaton decay and reheating period after the end of inflation in the non-minimal derivative coupling (NDC) model with chaotic potential. In general, this model is known to provide an enhanced slow-roll inflation caused by gravitationally enhanced friction. We find violent oscillations of Hubble parameter which induces oscillations of the sound speed squared, implying the Lagrangian instability of curvature perturbation $\zeta$ under the comoving gauge $\varphi=0$. Also, it is shown that the curvature perturbation blows up at $\dot{\phi}=0$, leading to the breakdown of the comoving gauge at $\dot{\phi}=0$. Therefore, we use the Newtonian gauge to perform the perturbation analysis where the Newtonian potential is employed as a physical variable. The curvature perturbation is not considered as a physical variable which describes a relevant perturbation during reheating.
|
2206.12256
|
Gamal G.L. Nashed
|
G. G. L. Nashed and Emmanuel N. Saridakis
|
New anisotropic star solutions in mimetic gravity
|
20 pages 10 figures, will appear in EPJP
|
Eur.Phys.J.Plus 138 (2023) 318
|
10.1140/epjp/s13360-023-03767-y
| null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
We extract new classes of anisotropic solutions in the framework of mimetic
gravity, by applying the Tolman-Finch-Skea metric and a specific anisotropy not
directly depending on it, and by matching smoothly the interior anisotropic
solution to the Schwarzschild exterior one. Then, in order to provide a
transparent picture we use the data from the 4U 1608-52 pulsar. We study the
profile of the energy density, as well as the radial and tangential pressures,
and we show that they are all positive and decrease towards the center of the
star. Furthermore, we investigate the anisotropy parameter and the anisotropic
force, that are both increasing functions of the radius, which implies that the
latter is repulsive. Additionally, by examining the radial and tangential
equation-of-state parameters, we show that they are monotonically increasing,
not corresponding to exotic matter. Concerning the metric potentials we find
that they have no singularity, either at the center of the star or at the
boundary. Furthermore, we verify that all energy conditions are satisfied, we
show that the radial and tangential sound speed squares are positive and
sub-luminal, and we find that the surface redshift satisfies the theoretical
requirement. Finally, in order to investigate the stability we apply the
Tolman-Oppenheimer-Volkoff equation, we perform the adiabatic index analysis,
and we examine the static case, showing that in all cases the star is stable.
|
[
{
"created": "Thu, 23 Jun 2022 08:03:18 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Feb 2023 07:58:31 GMT",
"version": "v2"
}
] |
2023-04-19
|
[
[
"Nashed",
"G. G. L.",
""
],
[
"Saridakis",
"Emmanuel N.",
""
]
] |
We extract new classes of anisotropic solutions in the framework of mimetic gravity, by applying the Tolman-Finch-Skea metric and a specific anisotropy not directly depending on it, and by matching smoothly the interior anisotropic solution to the Schwarzschild exterior one. Then, in order to provide a transparent picture we use the data from the 4U 1608-52 pulsar. We study the profile of the energy density, as well as the radial and tangential pressures, and we show that they are all positive and decrease towards the center of the star. Furthermore, we investigate the anisotropy parameter and the anisotropic force, that are both increasing functions of the radius, which implies that the latter is repulsive. Additionally, by examining the radial and tangential equation-of-state parameters, we show that they are monotonically increasing, not corresponding to exotic matter. Concerning the metric potentials we find that they have no singularity, either at the center of the star or at the boundary. Furthermore, we verify that all energy conditions are satisfied, we show that the radial and tangential sound speed squares are positive and sub-luminal, and we find that the surface redshift satisfies the theoretical requirement. Finally, in order to investigate the stability we apply the Tolman-Oppenheimer-Volkoff equation, we perform the adiabatic index analysis, and we examine the static case, showing that in all cases the star is stable.
|
1207.2914
|
Xiao Zhang
|
Yaohua Wang, Naqing Xie, Xiao Zhang
|
The positive energy theorem for asymptotically anti-de Sitter spacetimes
|
24 pages, revised substantially, the new energy-momentum inequality
proved. Appeared in Communications in Contemporary Mathematics
| null |
10.1142/S0219199715500157
| null |
gr-qc math.DG
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We establish the inequality for Henneaux-Teitelboim's total energy-momentum
for asymptotically anti-de Sitter initial data sets which are asymptotic to
arbitrary $t$-slice in anti-de Sitter spacetime. In particular, when $t=0$, it
generalizes Chru\'{s}ciel-Maerten-Tod's inequality in the center of AdS mass
coordinates. We also show that the determinant of energy-momentum endomorphism
${\bf Q}$ is the geometric invariant of asymptotically anti-de Sitter
spacetimes.
|
[
{
"created": "Thu, 12 Jul 2012 10:57:31 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Jul 2012 06:10:42 GMT",
"version": "v2"
},
{
"created": "Wed, 6 Feb 2013 04:10:49 GMT",
"version": "v3"
},
{
"created": "Mon, 25 Nov 2013 07:20:25 GMT",
"version": "v4"
},
{
"created": "Tue, 17 Feb 2015 01:28:33 GMT",
"version": "v5"
}
] |
2015-02-18
|
[
[
"Wang",
"Yaohua",
""
],
[
"Xie",
"Naqing",
""
],
[
"Zhang",
"Xiao",
""
]
] |
We establish the inequality for Henneaux-Teitelboim's total energy-momentum for asymptotically anti-de Sitter initial data sets which are asymptotic to arbitrary $t$-slice in anti-de Sitter spacetime. In particular, when $t=0$, it generalizes Chru\'{s}ciel-Maerten-Tod's inequality in the center of AdS mass coordinates. We also show that the determinant of energy-momentum endomorphism ${\bf Q}$ is the geometric invariant of asymptotically anti-de Sitter spacetimes.
|
gr-qc/0207088
|
Jeronimo Cortez
|
Alejandro Corichi, Jeronimo Cortez and Hernando Quevedo
|
On the Schroedinger Representation for a Scalar Field on Curved
Spacetime
|
11 pages, Revtex, no figures
|
Phys.Rev. D66 (2002) 085025
|
10.1103/PhysRevD.66.085025
| null |
gr-qc hep-th math-ph math.MP
| null |
It is generally known that linear (free) field theories are one of the few
QFT that are exactly soluble. In the Schroedinger functional description of a
scalar field on flat Minkowski spacetime and for flat embeddings, it is known
that the usual Fock representation is described by a Gaussian measure. In this
paper, arbitrary globally hyperbolic space-times and embeddings of the Cauchy
surface are considered. The classical structures relevant for quantization are
used for constructing the Schroedinger representation in the general case. It
is shown that in this case, the measure is also Gaussian. Possible implications
for the program of canonical quantization of midisuperspace models are pointed
out.
|
[
{
"created": "Wed, 24 Jul 2002 01:33:52 GMT",
"version": "v1"
}
] |
2016-08-31
|
[
[
"Corichi",
"Alejandro",
""
],
[
"Cortez",
"Jeronimo",
""
],
[
"Quevedo",
"Hernando",
""
]
] |
It is generally known that linear (free) field theories are one of the few QFT that are exactly soluble. In the Schroedinger functional description of a scalar field on flat Minkowski spacetime and for flat embeddings, it is known that the usual Fock representation is described by a Gaussian measure. In this paper, arbitrary globally hyperbolic space-times and embeddings of the Cauchy surface are considered. The classical structures relevant for quantization are used for constructing the Schroedinger representation in the general case. It is shown that in this case, the measure is also Gaussian. Possible implications for the program of canonical quantization of midisuperspace models are pointed out.
|
2404.17405
|
Miguel Zumalacarregui
|
Miguel Zumalac\'arregui
|
Lens Stochastic Diffraction: A Signature of Compact Structures in
Gravitational-Wave Data
|
5 pages, 4 figures. Comments welcome!
| null | null | null |
gr-qc astro-ph.CO astro-ph.HE hep-ph
|
http://creativecommons.org/licenses/by/4.0/
|
Every signal propagating through the universe is diffracted by the
gravitational fields of intervening objects, aka gravitational lenses.
Diffraction is most efficient when caused by compact lenses, which invariably
produce additional images of a source. The signals associated with additional
images are generically faint, but their collective effect may be detectable
with coherent sources, such as gravitational waves (GWs), where both amplitude
and phase are measured. Here, I describe lens stochastic diffraction (LSD):
Poisson-distributed fluctuations after GW events caused by compact lenses. The
amplitude and temporal distribution of these signals encode crucial information
about the mass and abundance of compact lenses. Through the collective
stochastic signal, LSD offers an order-of-magnitude improvement over single
lens analysis for objects with mass $\gtrsim 10^3 M_\odot$. This gain can
improve limits on compact dark-matter halos and allows next-generation
instruments to detect supermassive black holes, given the abundance inferred
from quasar luminosity studies.
|
[
{
"created": "Fri, 26 Apr 2024 13:31:13 GMT",
"version": "v1"
}
] |
2024-04-29
|
[
[
"Zumalacárregui",
"Miguel",
""
]
] |
Every signal propagating through the universe is diffracted by the gravitational fields of intervening objects, aka gravitational lenses. Diffraction is most efficient when caused by compact lenses, which invariably produce additional images of a source. The signals associated with additional images are generically faint, but their collective effect may be detectable with coherent sources, such as gravitational waves (GWs), where both amplitude and phase are measured. Here, I describe lens stochastic diffraction (LSD): Poisson-distributed fluctuations after GW events caused by compact lenses. The amplitude and temporal distribution of these signals encode crucial information about the mass and abundance of compact lenses. Through the collective stochastic signal, LSD offers an order-of-magnitude improvement over single lens analysis for objects with mass $\gtrsim 10^3 M_\odot$. This gain can improve limits on compact dark-matter halos and allows next-generation instruments to detect supermassive black holes, given the abundance inferred from quasar luminosity studies.
|
2212.14147
|
Oscar Lasso Andino
|
\'Alvaro Duenas-Vidal, Oscar Lasso Andino
|
The Jacobi metric approach for dynamical wormholes
|
14 pages
|
Gen Relativ Gravit 55, 9 (2023)
|
10.1007/s10714-022-03060-w
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present the Jacobi metric formalism for dynamical wormholes. We show that
in isotropic dynamical spacetimes , a first integral of the geodesic equations
can be found using the Jacobi metric, and without any use of geodesic equation.
This enables us to reduce the geodesic motion in dynamical wormholes to a
dynamics defined in a Riemannian manifold. Then, making use of the Jacobi
formalism, we study the circular stable orbits in the Jacobi metric framework
for the dynamical wormhole background. Finally, we also show that the Gaussian
curvature of the family of Jacobi metrics is directly related, as in the static
case, to the flare-out condition of the dynamical wormhole, giving a way to
characterize a wormhole spacetime by the sign of the Gaussian curvature of its
Jacobi metric only.
|
[
{
"created": "Thu, 29 Dec 2022 02:05:11 GMT",
"version": "v1"
}
] |
2023-01-02
|
[
[
"Duenas-Vidal",
"Álvaro",
""
],
[
"Andino",
"Oscar Lasso",
""
]
] |
We present the Jacobi metric formalism for dynamical wormholes. We show that in isotropic dynamical spacetimes , a first integral of the geodesic equations can be found using the Jacobi metric, and without any use of geodesic equation. This enables us to reduce the geodesic motion in dynamical wormholes to a dynamics defined in a Riemannian manifold. Then, making use of the Jacobi formalism, we study the circular stable orbits in the Jacobi metric framework for the dynamical wormhole background. Finally, we also show that the Gaussian curvature of the family of Jacobi metrics is directly related, as in the static case, to the flare-out condition of the dynamical wormhole, giving a way to characterize a wormhole spacetime by the sign of the Gaussian curvature of its Jacobi metric only.
|
1409.3391
|
I-Sheng Yang
|
Ue-Li Pen and I-Sheng Yang
|
Strong lensing interferometry for compact binaries
|
5 pages, 5 figures
|
Phys. Rev. D 91, 064044 (2015)
|
10.1103/PhysRevD.91.064044
| null |
gr-qc astro-ph.HE astro-ph.IM hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We propose a possibility to improve the current precision measurements on
compact binaries. When the orbital axis is almost perpendicular to our line of
sight, a pulsar behind its companion can form two strong-lensing images. These
images cannot be resolved, but we can use multi-wavelength interferometry to
accurately determine the passage through superior conjunction. This method does
not depend strongly on the stability of the pulse profile, and applies equally
well to both slow and fast pulsars. We discuss the possible improvement this
can bring to the bound on stochastic gravitational wave background and to
determine black hole spin. We also discuss the possibility of discovering a
suitable binary system by the Square Kilometer Array that our method can apply
to.
|
[
{
"created": "Thu, 11 Sep 2014 11:17:06 GMT",
"version": "v1"
}
] |
2015-03-25
|
[
[
"Pen",
"Ue-Li",
""
],
[
"Yang",
"I-Sheng",
""
]
] |
We propose a possibility to improve the current precision measurements on compact binaries. When the orbital axis is almost perpendicular to our line of sight, a pulsar behind its companion can form two strong-lensing images. These images cannot be resolved, but we can use multi-wavelength interferometry to accurately determine the passage through superior conjunction. This method does not depend strongly on the stability of the pulse profile, and applies equally well to both slow and fast pulsars. We discuss the possible improvement this can bring to the bound on stochastic gravitational wave background and to determine black hole spin. We also discuss the possibility of discovering a suitable binary system by the Square Kilometer Array that our method can apply to.
|
1510.08215
|
Bogeun Gwak
|
Bogeun Gwak, Bum-Hoon Lee
|
Thermodynamics of Three-dimensional Black Holes via Charged Particle
Absorption
|
6 pages
|
Phys. Lett. B755 (2016) 324-327
|
10.1016/j.physletb.2016.02.028
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We have shown that changes occur in a (2+1)-dimensional charged black hole by
adding a charged probe. The particle increases the entropy of the black hole
and guarantees the second law of thermodynamics. The first law of
thermodynamics is derived from the change in the black hole mass. Using the
particle absorption, we test the extremal black hole and find out that the mass
of the extremal black hole increases more than the electric charge. Therefore,
the outer horizon of the black hole still exists. However, the extremal
condition becomes non-extremal.
|
[
{
"created": "Wed, 28 Oct 2015 07:33:58 GMT",
"version": "v1"
}
] |
2017-12-01
|
[
[
"Gwak",
"Bogeun",
""
],
[
"Lee",
"Bum-Hoon",
""
]
] |
We have shown that changes occur in a (2+1)-dimensional charged black hole by adding a charged probe. The particle increases the entropy of the black hole and guarantees the second law of thermodynamics. The first law of thermodynamics is derived from the change in the black hole mass. Using the particle absorption, we test the extremal black hole and find out that the mass of the extremal black hole increases more than the electric charge. Therefore, the outer horizon of the black hole still exists. However, the extremal condition becomes non-extremal.
|
0908.4006
|
John T. Whelan
|
Stephen Fairhurst, Gianluca M Guidi, Patrice Hello, John T Whelan,
Graham Woan
|
Current status of gravitational-wave observations
|
21 pages, LaTeX, uses svjour3.cls, 1 figure, for GRG special issue on
Einstein Telescope
|
Gen.Rel.Grav.43:387-407,2011
|
10.1007/s10714-010-1009-1
|
LIGO-P0900092
|
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The first generation of gravitational wave interferometric detectors has
taken data at, or close to, their design sensitivity. This data has been
searched for a broad range of gravitational wave signatures. An overview of
gravitational wave search methods and results are presented. Searches for
gravitational waves from unmodelled burst sources, compact binary coalescences,
continuous wave sources and stochastic backgrounds are discussed.
|
[
{
"created": "Thu, 27 Aug 2009 13:07:31 GMT",
"version": "v1"
}
] |
2011-01-28
|
[
[
"Fairhurst",
"Stephen",
""
],
[
"Guidi",
"Gianluca M",
""
],
[
"Hello",
"Patrice",
""
],
[
"Whelan",
"John T",
""
],
[
"Woan",
"Graham",
""
]
] |
The first generation of gravitational wave interferometric detectors has taken data at, or close to, their design sensitivity. This data has been searched for a broad range of gravitational wave signatures. An overview of gravitational wave search methods and results are presented. Searches for gravitational waves from unmodelled burst sources, compact binary coalescences, continuous wave sources and stochastic backgrounds are discussed.
|
2312.16736
|
Remo Garattini
|
R. Garattini and A.G. Tzikas
|
Traversable Wormholes induced by Stress Energy Conservation: combining
Casimir Energy with a scalar field
|
LaTeX 14 pages
| null | null | null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
We investigate possible manifolds characterizing traversable wormholes in the
presence of a scalar field, which is minimally coupled to gravity and has both
kinetic and potential energy. The feature of traversability requires the
violation of the null energy condition, which, in turn, signals the existence
of exotic matter with negative energy density. For this reason, we impose a
hypothetical Casimir apparatus with plates positioned at a distance either
parametrically fixed or radially varying. The main feature of all the derived
solutions is the conservation of the Stress Energy Tensor. Such a conservation
though requires the introduction of an auxiliary field, which we interpret as a
gravitational response of the Traversable Wormhole to the original source.
Interestingly, the only case that seems to avoid the necessity for such an
auxiliary field, is the one involving a scalar field with a potential, in
combination with a Casimir device with fixed plates.
|
[
{
"created": "Wed, 27 Dec 2023 22:35:08 GMT",
"version": "v1"
}
] |
2024-01-01
|
[
[
"Garattini",
"R.",
""
],
[
"Tzikas",
"A. G.",
""
]
] |
We investigate possible manifolds characterizing traversable wormholes in the presence of a scalar field, which is minimally coupled to gravity and has both kinetic and potential energy. The feature of traversability requires the violation of the null energy condition, which, in turn, signals the existence of exotic matter with negative energy density. For this reason, we impose a hypothetical Casimir apparatus with plates positioned at a distance either parametrically fixed or radially varying. The main feature of all the derived solutions is the conservation of the Stress Energy Tensor. Such a conservation though requires the introduction of an auxiliary field, which we interpret as a gravitational response of the Traversable Wormhole to the original source. Interestingly, the only case that seems to avoid the necessity for such an auxiliary field, is the one involving a scalar field with a potential, in combination with a Casimir device with fixed plates.
|
2205.05683
|
Muhammad Sharif
|
M. Sharif and Ayesha Anjum
|
Impact of Charge on the Complexity of Static Sphere in
$f(R,\textbf{T}^{2})$ Gravity
|
24 pages, 3 figures, to appear in EPJP
|
Eur. Phys. J. Plus. 137(2022)602
| null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This paper investigates the complexity of a charged static sphere filled with
anisotropic matter in the background of energy-momentum squared gravity. For
this purpose, we evaluate the modified field and conservation equations to
determine the structure of celestial system. The mass function is calculated
through Misner-Sharp as well as Tolman mass definitions. The complexity of a
self-gravitating system depends on different factors such as anisotropic
pressure, electromagnetic field, energy density inhomogeneity, etc. We
formulate the structure scalars by the orthogonal decomposition of the Riemann
tensor to develop a complexity factor containing all vital features of the
stellar structure. The vanishing complexity condition is achieved by setting
the complexity factor equal to zero. Finally, we construct two static solutions
by utilizing the energy density of Gokhroo-Mehra solution as well as the
polytropic equation of state along with the zero complexity condition. It is
found that electromagnetic field decreases the complexity of stellar structure.
|
[
{
"created": "Wed, 11 May 2022 09:07:54 GMT",
"version": "v1"
}
] |
2022-05-19
|
[
[
"Sharif",
"M.",
""
],
[
"Anjum",
"Ayesha",
""
]
] |
This paper investigates the complexity of a charged static sphere filled with anisotropic matter in the background of energy-momentum squared gravity. For this purpose, we evaluate the modified field and conservation equations to determine the structure of celestial system. The mass function is calculated through Misner-Sharp as well as Tolman mass definitions. The complexity of a self-gravitating system depends on different factors such as anisotropic pressure, electromagnetic field, energy density inhomogeneity, etc. We formulate the structure scalars by the orthogonal decomposition of the Riemann tensor to develop a complexity factor containing all vital features of the stellar structure. The vanishing complexity condition is achieved by setting the complexity factor equal to zero. Finally, we construct two static solutions by utilizing the energy density of Gokhroo-Mehra solution as well as the polytropic equation of state along with the zero complexity condition. It is found that electromagnetic field decreases the complexity of stellar structure.
|
gr-qc/0509069
|
Stephane Fay
|
Stephane Fay
|
Homogeneous cosmology dynamics revealed by Hamiltonian ADM formalism
|
23 pages, 3 figures, book chapter
|
Quantum cosmology research trends. Horizons in world physics, Nova
publishers, vol 246, 2005
| null | null |
gr-qc
| null |
We study the homogeneous but anisotropic cosmological models of Bianchi in
presence of a massive scalar field using the ADM Hamiltonian formalism. We
begin to describe the main steps to find the ADM Hamiltonian of the General
Relativity with a massive scalar field and then we study the dynamics of the
flat Bianchi type $I$ anisotropic Universe according to initial and final
values of this Hamiltonian and sign of the potential. After a brief recall of
the conditions necessary to isotropise an anisotropic Bianchi class A model
with such a field, we extend them to a non minimally coupled scalar field by
using a conformal transformation of the metric which casts the General
Relativity with a scalar field into a scalar-tensor theory. The new line
element then corresponds to the so-called Brans-Dicke frame, the former one
being the Einstein frame. Then, we study the isotropisation process of the
Bianchi class A model when we consider the low energy form of the string theory
without its antisymmetric tensor and the Brans-Dicke theory with some
exponential or power laws of the scalar field for the potential. Finally,
assuming an isotropic Universe such as all the metric functions behave as some
power or exponential laws of the proper time, we find the conditions such that
the gravitation function and the potential of the scalar field are bounded as
it is observed today, and compare them with the necessary conditions for
isotropy.
|
[
{
"created": "Fri, 16 Sep 2005 15:33:51 GMT",
"version": "v1"
}
] |
2014-04-15
|
[
[
"Fay",
"Stephane",
""
]
] |
We study the homogeneous but anisotropic cosmological models of Bianchi in presence of a massive scalar field using the ADM Hamiltonian formalism. We begin to describe the main steps to find the ADM Hamiltonian of the General Relativity with a massive scalar field and then we study the dynamics of the flat Bianchi type $I$ anisotropic Universe according to initial and final values of this Hamiltonian and sign of the potential. After a brief recall of the conditions necessary to isotropise an anisotropic Bianchi class A model with such a field, we extend them to a non minimally coupled scalar field by using a conformal transformation of the metric which casts the General Relativity with a scalar field into a scalar-tensor theory. The new line element then corresponds to the so-called Brans-Dicke frame, the former one being the Einstein frame. Then, we study the isotropisation process of the Bianchi class A model when we consider the low energy form of the string theory without its antisymmetric tensor and the Brans-Dicke theory with some exponential or power laws of the scalar field for the potential. Finally, assuming an isotropic Universe such as all the metric functions behave as some power or exponential laws of the proper time, we find the conditions such that the gravitation function and the potential of the scalar field are bounded as it is observed today, and compare them with the necessary conditions for isotropy.
|
gr-qc/9310022
|
Huw Price
|
Huw Price
|
Cosmology, Time's Arrow, and That Old Double Standard
|
26 pages, in LaTeX with 3 figures appended as postscript file.
(Written for Time's Arrows Today Conference, UBC, Vancouver, June 1992;
forthcoming in Savitt, S. (ed), 'Time's Arrows Today', Cambridge University
Press, 1994.)
| null | null | null |
gr-qc
| null |
It is widely accepted that temporal asymmetry is largely a cosmological
problem; the task of explaining temporal asymmetry reduces in the main to that
of explaining an aspect of the condition of the early universe. However,
cosmologists who discuss these issues often make mistakes similar to those that
plagued nineteenth century discussions of the statistical foundations of
thermodynamics. In particular, they are often guilty of applying temporal
"double standards" of various kinds---e.g., in failing to recognise that
certain statistical arguments apply with equal force in either temporal
direction. This paper aims to clarify the issue as to what would count as
adequate explanation of cosmological time asymmetry. A particular concern is
the question whether it is possible to explain why entropy is low near the Big
Bang without showing that it must also be low near a Big Crunch, in the event
that the universe recollapses. I criticise some of the objections raised to
this possibility, showing that these too often depend on a temporal double
standard. I also discuss briefly some issues that arise if we take the view
seriously. (Could we observe a time- reversing future, for example?)
|
[
{
"created": "Fri, 15 Oct 1993 04:39:37 GMT",
"version": "v1"
}
] |
2009-09-25
|
[
[
"Price",
"Huw",
""
]
] |
It is widely accepted that temporal asymmetry is largely a cosmological problem; the task of explaining temporal asymmetry reduces in the main to that of explaining an aspect of the condition of the early universe. However, cosmologists who discuss these issues often make mistakes similar to those that plagued nineteenth century discussions of the statistical foundations of thermodynamics. In particular, they are often guilty of applying temporal "double standards" of various kinds---e.g., in failing to recognise that certain statistical arguments apply with equal force in either temporal direction. This paper aims to clarify the issue as to what would count as adequate explanation of cosmological time asymmetry. A particular concern is the question whether it is possible to explain why entropy is low near the Big Bang without showing that it must also be low near a Big Crunch, in the event that the universe recollapses. I criticise some of the objections raised to this possibility, showing that these too often depend on a temporal double standard. I also discuss briefly some issues that arise if we take the view seriously. (Could we observe a time- reversing future, for example?)
|
gr-qc/0507020
|
L\'aszl\'o \'A Gergely
|
L\'aszl\'o \'A. Gergely, Zolt\'an Kov\'acs
|
Gravitational dynamics in s+1+1 dimensions
|
published version, typo in Eq. (47) corrected
|
Phys.Rev. D72 (2005) 064015
|
10.1103/PhysRevD.72.064015
| null |
gr-qc astro-ph hep-th
| null |
We present the concomitant decomposition of an (s+2)-dimensional spacetime
both with respect to a timelike and a spacelike direction. The formalism we
develop is suited for the study of the initial value problem and for canonical
gravitational dynamics in brane-world scenarios. The bulk metric is replaced by
two sets of variables. The first set consist of one tensorial (the induced
metric $g_{ij}$), one vectorial ($M^{i}$) and one scalar ($M$) dynamical
quantity, all defined on the s-space. Their time evolutions are related to the
second fundamental form (the extrinsic curvature $K_{ij}$), the normal
fundamental form ($\mathcal{K}^{i}$) and normal fundamental scalar
($\mathcal{K}$), respectively. The non-dynamical set of variables is given by
the lapse function and the shift vector, which however has one component less.
The missing component is due to the externally imposed constraint, which states
that physical trajectories are confined to the (s+1)-dimensional brane. The
pair of dynamical variables ($g_{ij}$, $K_{ij}$), well-known from the
ADM-decomposition is supplemented by the pairs ($M^{i}$, $\mathcal{K}^{i}$) and
($M$, $\mathcal{K}$) due to the bulk curvature. We give all projections of the
junction condition across the brane and prove that for a perfect fluid brane
neither of the dynamical variables has jump across the brane. Finally we
complete the set of equations needed for gravitational dynamics by deriving the
evolution equations of $K_{ij}$, $\mathcal{K}^{i}$ and $\mathcal{K}$ on a brane
with arbitrary matter.
|
[
{
"created": "Wed, 6 Jul 2005 13:56:36 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Mar 2006 13:41:08 GMT",
"version": "v2"
}
] |
2009-11-11
|
[
[
"Gergely",
"László Á.",
""
],
[
"Kovács",
"Zoltán",
""
]
] |
We present the concomitant decomposition of an (s+2)-dimensional spacetime both with respect to a timelike and a spacelike direction. The formalism we develop is suited for the study of the initial value problem and for canonical gravitational dynamics in brane-world scenarios. The bulk metric is replaced by two sets of variables. The first set consist of one tensorial (the induced metric $g_{ij}$), one vectorial ($M^{i}$) and one scalar ($M$) dynamical quantity, all defined on the s-space. Their time evolutions are related to the second fundamental form (the extrinsic curvature $K_{ij}$), the normal fundamental form ($\mathcal{K}^{i}$) and normal fundamental scalar ($\mathcal{K}$), respectively. The non-dynamical set of variables is given by the lapse function and the shift vector, which however has one component less. The missing component is due to the externally imposed constraint, which states that physical trajectories are confined to the (s+1)-dimensional brane. The pair of dynamical variables ($g_{ij}$, $K_{ij}$), well-known from the ADM-decomposition is supplemented by the pairs ($M^{i}$, $\mathcal{K}^{i}$) and ($M$, $\mathcal{K}$) due to the bulk curvature. We give all projections of the junction condition across the brane and prove that for a perfect fluid brane neither of the dynamical variables has jump across the brane. Finally we complete the set of equations needed for gravitational dynamics by deriving the evolution equations of $K_{ij}$, $\mathcal{K}^{i}$ and $\mathcal{K}$ on a brane with arbitrary matter.
|
2310.05591
|
Lei Ming
|
Lei Ming, Shi-Dong Liang, Hong-Hao Zhang and Tiberiu Harko
|
From the Weyl-Schr\"{o}dinger connection to the accelerating Universe --
extending Einstein's gravity via a length preserving nonmetricity
|
21 pages, 11 figures
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
One of the important extensions of Riemann geometry is Weyl geometry, which
is essentially based on the ideas of conformal invariance and nonmetricity. A
similar non-Riemannian geometry was proposed by Erwin Schr\"{o}dinger in the
late 1940s, in a geometry which is simpler, and (probably) more elegant than
the Weyl geometry. Even it contains nonmetricity, the Schr\"{o}dinger
connection preserves the length of vectors under parallel transport, and thus
seems to be more physical than the Weyl connection. Interestingly enough,
Schr\"{o}dinger's approach did not attract much interest in the field of
gravitational physics. It is the goal of the present paper to reconsider the
Schr\"{o}dinger geometry as a potential candidate for a gravitational theory
extending standard general relativity. We consider a gravitational action
constructed from a length preserving non-metricity, in the absence of torsion,
and investigate its variation in both Palatini and metric formalisms. While the
Palatini variation leads to standard general relativity, the metric version of
the theory adds some non-metricity dependent extra terms in the gravitational
Einstein equations, which can be interpreted as representing a geometric type
dark energy. After obtaining the generalized Friedmann equations, we analyze in
detail the cosmological implications of the theory, by considering two distinct
models, corresponding to a dark energy satisfying a linear equation of state,
and to conserved matter energy, respectively. In both cases we compare the
predictions of the Weyl-Schr\"{o}dinger cosmology with a set of observational
data for the Hubble function, and with the results of the $\Lambda$CDM standard
paradigm.
|
[
{
"created": "Mon, 9 Oct 2023 10:22:44 GMT",
"version": "v1"
}
] |
2023-10-10
|
[
[
"Ming",
"Lei",
""
],
[
"Liang",
"Shi-Dong",
""
],
[
"Zhang",
"Hong-Hao",
""
],
[
"Harko",
"Tiberiu",
""
]
] |
One of the important extensions of Riemann geometry is Weyl geometry, which is essentially based on the ideas of conformal invariance and nonmetricity. A similar non-Riemannian geometry was proposed by Erwin Schr\"{o}dinger in the late 1940s, in a geometry which is simpler, and (probably) more elegant than the Weyl geometry. Even it contains nonmetricity, the Schr\"{o}dinger connection preserves the length of vectors under parallel transport, and thus seems to be more physical than the Weyl connection. Interestingly enough, Schr\"{o}dinger's approach did not attract much interest in the field of gravitational physics. It is the goal of the present paper to reconsider the Schr\"{o}dinger geometry as a potential candidate for a gravitational theory extending standard general relativity. We consider a gravitational action constructed from a length preserving non-metricity, in the absence of torsion, and investigate its variation in both Palatini and metric formalisms. While the Palatini variation leads to standard general relativity, the metric version of the theory adds some non-metricity dependent extra terms in the gravitational Einstein equations, which can be interpreted as representing a geometric type dark energy. After obtaining the generalized Friedmann equations, we analyze in detail the cosmological implications of the theory, by considering two distinct models, corresponding to a dark energy satisfying a linear equation of state, and to conserved matter energy, respectively. In both cases we compare the predictions of the Weyl-Schr\"{o}dinger cosmology with a set of observational data for the Hubble function, and with the results of the $\Lambda$CDM standard paradigm.
|
2208.11913
|
Lijing Shao
|
Ziming Wang, Junjie Zhao, Zihe An, Lijing Shao, Zhoujian Cao
|
Simultaneous bounds on the gravitational dipole radiation and varying
gravitational constant from compact binary inspirals
|
16 pages, 9 figures, 2 tables; accepted by Physics Letters B
|
Physics Letters B 834 (2022) 137416
|
10.1016/j.physletb.2022.137416
| null |
gr-qc astro-ph.HE
|
http://creativecommons.org/licenses/by/4.0/
|
Compact binaries are an important class of gravitational-wave (GW) sources
that can be detected by current and future GW observatories. They provide a
testbed for general relativity (GR) in the highly dynamical strong-field
regime. Here, we use GWs from inspiraling binary neutron stars and binary black
holes to investigate dipolar gravitational radiation (DGR) and varying
gravitational constant predicted by some alternative theories to GR, such as
the scalar-tensor gravity. Within the parametrized post-Einsteinian framework,
we introduce the parametrization of these two effects simultaneously into
compact binaries' inspiral waveform and perform the Fisher-information-matrix
analysis to estimate their simultaneous bounds. In general, the space-based GW
detectors can give a tighter limit than ground-based ones. The tightest
constraints can reach $\sigma_B<3\times10^{-11}$ for the DGR parameter $B$ and
$\sigma_{\dot{G}}/G < 7\times10^{-9} \, {\rm yr}^{-1} $ for the varying $G$,
when the time to coalescence of the GW event is close to the lifetime of
space-based detectors. In addition, we analyze the correlation between these
two effects and highlight the importance of considering both effects in order
to arrive at more realistic results.
|
[
{
"created": "Thu, 25 Aug 2022 07:50:53 GMT",
"version": "v1"
}
] |
2022-09-12
|
[
[
"Wang",
"Ziming",
""
],
[
"Zhao",
"Junjie",
""
],
[
"An",
"Zihe",
""
],
[
"Shao",
"Lijing",
""
],
[
"Cao",
"Zhoujian",
""
]
] |
Compact binaries are an important class of gravitational-wave (GW) sources that can be detected by current and future GW observatories. They provide a testbed for general relativity (GR) in the highly dynamical strong-field regime. Here, we use GWs from inspiraling binary neutron stars and binary black holes to investigate dipolar gravitational radiation (DGR) and varying gravitational constant predicted by some alternative theories to GR, such as the scalar-tensor gravity. Within the parametrized post-Einsteinian framework, we introduce the parametrization of these two effects simultaneously into compact binaries' inspiral waveform and perform the Fisher-information-matrix analysis to estimate their simultaneous bounds. In general, the space-based GW detectors can give a tighter limit than ground-based ones. The tightest constraints can reach $\sigma_B<3\times10^{-11}$ for the DGR parameter $B$ and $\sigma_{\dot{G}}/G < 7\times10^{-9} \, {\rm yr}^{-1} $ for the varying $G$, when the time to coalescence of the GW event is close to the lifetime of space-based detectors. In addition, we analyze the correlation between these two effects and highlight the importance of considering both effects in order to arrive at more realistic results.
|
gr-qc/0512156
|
Gamal Nashed G.L.
|
Gamal G.L. Nashed
|
Axially symmetric solution in Teleparallel Theory of Gravitation
|
9 pages, Latex
| null | null | null |
gr-qc
| null |
An exact solution has an axial symmetry is obtained in the teleparallel
theory of gravitation. The associated metric has the structure function
G(xi)=1-xi^2-2mA(xi)^3. The cubic nature of the structure function can make
calculations cumbersome. Using a coordinate transformation we get a tetrad that
its associated metric has the structure function in a factorisable form. This
new form has the advantage that its roots are now trivial to write down. The
singularities of the obtained tetrad are studied. Using another coordinate
transformation we get a tetrad that its associated metric gives the
Schwarzschild spacetime. Calculate the energy content of this tetrad we get a
meaningless result!
|
[
{
"created": "Wed, 28 Dec 2005 09:12:54 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Nashed",
"Gamal G. L.",
""
]
] |
An exact solution has an axial symmetry is obtained in the teleparallel theory of gravitation. The associated metric has the structure function G(xi)=1-xi^2-2mA(xi)^3. The cubic nature of the structure function can make calculations cumbersome. Using a coordinate transformation we get a tetrad that its associated metric has the structure function in a factorisable form. This new form has the advantage that its roots are now trivial to write down. The singularities of the obtained tetrad are studied. Using another coordinate transformation we get a tetrad that its associated metric gives the Schwarzschild spacetime. Calculate the energy content of this tetrad we get a meaningless result!
|
2005.10024
|
Hossein Mohseni Sadjadi
|
H. Mohseni Sadjadi
|
On cosmic acceleration in four dimensional Einstein-Gauss-Bonnet gravity
|
major revision, 17 pages, typos corrected, accepted by Physics of the
Dark Universe
|
Phys. Dark Univ. 30, 100728 (2020)
|
10.1016/j.dark.2020.100728
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the possibility that in the model introduced in \cite{GBN}, the
Gauss-Bonnet term alone gives rise to the cosmic acceleration and
super-acceleration in four-dimensional FLRW space-time at the late time. We
also discuss transitions from deceleration to acceleration and acceleration to
super-acceleration. We show that the Gauss-Bonnet invariant can drive the
acceleration in the low redshift provided that its regularized coefficient has
the same order as the squared of the ratio of the reduced Planck mass to the
Hubble parameter.
|
[
{
"created": "Tue, 19 May 2020 10:43:15 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Jul 2020 10:00:12 GMT",
"version": "v2"
},
{
"created": "Fri, 3 Jul 2020 09:24:28 GMT",
"version": "v3"
},
{
"created": "Thu, 24 Sep 2020 12:58:09 GMT",
"version": "v4"
}
] |
2021-04-26
|
[
[
"Sadjadi",
"H. Mohseni",
""
]
] |
We study the possibility that in the model introduced in \cite{GBN}, the Gauss-Bonnet term alone gives rise to the cosmic acceleration and super-acceleration in four-dimensional FLRW space-time at the late time. We also discuss transitions from deceleration to acceleration and acceleration to super-acceleration. We show that the Gauss-Bonnet invariant can drive the acceleration in the low redshift provided that its regularized coefficient has the same order as the squared of the ratio of the reduced Planck mass to the Hubble parameter.
|
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