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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1607.05473 | Donato Bini | Donato Bini and Bahram Mashhoon | Relativistic Gravity Gradiometry: The Mashhoon--Theiss Effect | 23 pages; revtex macros used; two figures; v2: references added,
presentation improved; v3: subsection V(B) added, other additions and
improvements | Phys. Rev. D 94, 124009 (2016) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In general relativity, relativistic gravity gradiometry involves the
measurement of the relativistic tidal matrix, which is theoretically obtained
from the projection of the Riemann curvature tensor onto the orthonormal tetrad
frame of an observer. The observer's 4-velocity vector defines its local
temporal axis and its local spatial frame is defined by a set of three
orthonormal nonrotating gyro directions. The general tidal matrix for the
timelike geodesics of Kerr spacetime has been calculated by Marck\cite{Marck}.
We are interested in the measured components of the curvature tensor along the
inclined "circular" geodesic orbit of a test mass about a slowly rotating
astronomical object of mass $M$ and angular momentum $J$. Therefore, we
specialize Marck's results to such a "circular" orbit that is tilted with
respect to the equatorial plane of the Kerr source. To linear order in $J$, we
recover the Mashhoon--Theiss effect, which is due to a small denominator
("resonance") phenomenon involving the frequency of geodetic precession. The
Mashhoon--Theiss effect shows up as a special long-period gravitomagnetic part
of the relativistic tidal matrix. The physical interpretation of this effect is
briefly discussed.
| [
{
"created": "Tue, 19 Jul 2016 09:10:21 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Aug 2016 09:07:45 GMT",
"version": "v2"
},
{
"created": "Tue, 6 Dec 2016 08:26:50 GMT",
"version": "v3"
}
] | 2016-12-07 | [
[
"Bini",
"Donato",
""
],
[
"Mashhoon",
"Bahram",
""
]
] | In general relativity, relativistic gravity gradiometry involves the measurement of the relativistic tidal matrix, which is theoretically obtained from the projection of the Riemann curvature tensor onto the orthonormal tetrad frame of an observer. The observer's 4-velocity vector defines its local temporal axis and its local spatial frame is defined by a set of three orthonormal nonrotating gyro directions. The general tidal matrix for the timelike geodesics of Kerr spacetime has been calculated by Marck\cite{Marck}. We are interested in the measured components of the curvature tensor along the inclined "circular" geodesic orbit of a test mass about a slowly rotating astronomical object of mass $M$ and angular momentum $J$. Therefore, we specialize Marck's results to such a "circular" orbit that is tilted with respect to the equatorial plane of the Kerr source. To linear order in $J$, we recover the Mashhoon--Theiss effect, which is due to a small denominator ("resonance") phenomenon involving the frequency of geodetic precession. The Mashhoon--Theiss effect shows up as a special long-period gravitomagnetic part of the relativistic tidal matrix. The physical interpretation of this effect is briefly discussed. |
1512.05866 | Josef Kluson | M. Chaichian, A. Ghalee, J. Kluson | Restricted f(R) Gravity and Its Cosmological Implications | 22 pages, v2:minor corrections, figure added, v3:version published in
PRD | Phys. Rev. D 93, 104020 (2016) | 10.1103/PhysRevD.93.104020 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the f(R) theory of gravity with broken diffeomorphism due to
the change of the coefficient in front of the total divergence term in the
(3+1)-decomposition of the scalar curvature. We perform the canonical analysis
of this theory and show that its consistent, i.e. with no unphysical degrees of
freedom, form is equivalent to the low-energy limit of the non-projectable f(R)
Horava-Lifshitz theory of gravity. We also analyze its cosmological solutions
and show that the de Sitter solution can be obtained also in the case of this
broken symmetry. The consequences of the proposed theory on the asymptotic
solutions of a few specific models in the cosmological context are also
presented.
| [
{
"created": "Fri, 18 Dec 2015 07:31:51 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Feb 2016 07:42:11 GMT",
"version": "v2"
},
{
"created": "Wed, 27 Apr 2016 06:40:00 GMT",
"version": "v3"
}
] | 2016-05-18 | [
[
"Chaichian",
"M.",
""
],
[
"Ghalee",
"A.",
""
],
[
"Kluson",
"J.",
""
]
] | We investigate the f(R) theory of gravity with broken diffeomorphism due to the change of the coefficient in front of the total divergence term in the (3+1)-decomposition of the scalar curvature. We perform the canonical analysis of this theory and show that its consistent, i.e. with no unphysical degrees of freedom, form is equivalent to the low-energy limit of the non-projectable f(R) Horava-Lifshitz theory of gravity. We also analyze its cosmological solutions and show that the de Sitter solution can be obtained also in the case of this broken symmetry. The consequences of the proposed theory on the asymptotic solutions of a few specific models in the cosmological context are also presented. |
2404.01083 | Alejandro C\'ardenas-Avenda\~no | Alejandro C\'ardenas-Avenda\~no, Lennox Keeble, Alexandru Lupsasca | Assessing the impact of instrument noise and astrophysical fluctuations
on measurements of the first black hole photon ring | 20+1 pages, 13 figures. V2: Minor changes to match the published
version | Phys. Rev. D 109, 124052, 2024 | 10.1103/PhysRevD.109.124052 | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | Currently envisioned extensions of the Event Horizon Telescope to space will
soon target the black hole photon ring: a narrow ring-shaped imprint of a black
hole's strong gravity produced in its images by highly bent photon
trajectories. In principle, the shape of the photon ring encodes information
about the geometry of the underlying black hole spacetime. In practice,
however, whether or not this information can be extracted from the ring shape
depends on several factors, ranging from the astrophysical details of the
emitting source (such as the magnitude of its plasma fluctuations) to the
specific configuration of the interferometric array (such as the separation
between its telescopes, or the level of noise in its instruments). Here, we
employ a phenomenological model to assess the impact of astrophysical
fluctuations and instrument noise on the inferred shape of the photon ring. Our
systematic study of several astrophysical profiles suggests that this shape can
be measured even in the presence of instrument noise across a wide range of
baselines. The measurement accuracy and precision appear relatively insensitive
to the noise level, up to a sharp threshold beyond which any measurement
becomes incredibly challenging (at least without recourse to more sophisticated
data analysis methods). Encouragingly, we find that only a few snapshot images
are generally needed to overcome the impact of astrophysical fluctuations and
correctly infer the ring diameter. Inference becomes more challenging when
analyzing the visibility amplitude in a baseline window that is not entirely
dominated by a single photon ring. Nevertheless, in most cases, it is still
possible to fit a ring shape with the correct fractional asymmetry. These
results provide excellent prospects for future precision measurements of black
hole spin and fundamental astrophysics via black hole imaging.
| [
{
"created": "Mon, 1 Apr 2024 12:26:03 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Jun 2024 12:37:49 GMT",
"version": "v2"
}
] | 2024-06-24 | [
[
"Cárdenas-Avendaño",
"Alejandro",
""
],
[
"Keeble",
"Lennox",
""
],
[
"Lupsasca",
"Alexandru",
""
]
] | Currently envisioned extensions of the Event Horizon Telescope to space will soon target the black hole photon ring: a narrow ring-shaped imprint of a black hole's strong gravity produced in its images by highly bent photon trajectories. In principle, the shape of the photon ring encodes information about the geometry of the underlying black hole spacetime. In practice, however, whether or not this information can be extracted from the ring shape depends on several factors, ranging from the astrophysical details of the emitting source (such as the magnitude of its plasma fluctuations) to the specific configuration of the interferometric array (such as the separation between its telescopes, or the level of noise in its instruments). Here, we employ a phenomenological model to assess the impact of astrophysical fluctuations and instrument noise on the inferred shape of the photon ring. Our systematic study of several astrophysical profiles suggests that this shape can be measured even in the presence of instrument noise across a wide range of baselines. The measurement accuracy and precision appear relatively insensitive to the noise level, up to a sharp threshold beyond which any measurement becomes incredibly challenging (at least without recourse to more sophisticated data analysis methods). Encouragingly, we find that only a few snapshot images are generally needed to overcome the impact of astrophysical fluctuations and correctly infer the ring diameter. Inference becomes more challenging when analyzing the visibility amplitude in a baseline window that is not entirely dominated by a single photon ring. Nevertheless, in most cases, it is still possible to fit a ring shape with the correct fractional asymmetry. These results provide excellent prospects for future precision measurements of black hole spin and fundamental astrophysics via black hole imaging. |
gr-qc/9807055 | Andrew Philip Billyard | Andrew Billyard, Alan A Coley, Jesus Ibanez | On the Asymptotic Behaviour of Cosmological Models in Scalar-Tensor
Theories of Gravity | 22 pages, submitted to Phys Rev D | Phys.Rev. D59 (1999) 023507 | 10.1103/PhysRevD.59.023507 | Dal-98-07 | gr-qc | null | We study the qualitative properties of cosmological models in scalar-tensor
theories of gravity by exploiting the formal equivalence of these theories with
general relativity minimally coupled to a scalar field under a conformal
transformation and field redefinition. In particular, we investigate the
asymptotic behaviour of spatially homogeneous cosmological models in a class of
scalar-tensor theories which are conformally equivalent to general relativistic
Bianchi cosmologies with a scalar field and an exponential potential whose
qualitative features have been studied previously. Particular attention is
focussed on those scalar-tensor theory cosmological models, which are shown to
be self-similar, that correspond to general relativistic models that play an
important r\^{o}le in describing the asymptotic behaviour of more general
models (e.g., those cosmological models that act as early-time and late-time
attractors).
| [
{
"created": "Mon, 20 Jul 1998 17:28:43 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Billyard",
"Andrew",
""
],
[
"Coley",
"Alan A",
""
],
[
"Ibanez",
"Jesus",
""
]
] | We study the qualitative properties of cosmological models in scalar-tensor theories of gravity by exploiting the formal equivalence of these theories with general relativity minimally coupled to a scalar field under a conformal transformation and field redefinition. In particular, we investigate the asymptotic behaviour of spatially homogeneous cosmological models in a class of scalar-tensor theories which are conformally equivalent to general relativistic Bianchi cosmologies with a scalar field and an exponential potential whose qualitative features have been studied previously. Particular attention is focussed on those scalar-tensor theory cosmological models, which are shown to be self-similar, that correspond to general relativistic models that play an important r\^{o}le in describing the asymptotic behaviour of more general models (e.g., those cosmological models that act as early-time and late-time attractors). |
gr-qc/0108075 | Yosef Zlochower | Sascha Husa, Yosef Zlochower, Roberto Gomez, Jeffrey Winicour | Retarded radiation from colliding black holes in the close limit | 14 pages, 13 figures, revtex4 | Phys.Rev. D65 (2002) 084034 | 10.1103/PhysRevD.65.084034 | null | gr-qc | null | We use null hypersurface techniques in a new approach to calculate the
retarded waveform from a binary black hole merger in the close approximation.
The process of removing ingoing radiation from the system leads to two notable
features in the shape of the close approximation waveform for a head-on
collision of black holes: (i) an initial quasinormal ringup and (ii) weak
sensitivity to the parameter controlling the collision velocity. Feature (ii)
is unexpected and has the potential importance of enabling the design of an
efficient template for extracting the gravitational wave signal from the noise.
| [
{
"created": "Wed, 29 Aug 2001 20:49:00 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Husa",
"Sascha",
""
],
[
"Zlochower",
"Yosef",
""
],
[
"Gomez",
"Roberto",
""
],
[
"Winicour",
"Jeffrey",
""
]
] | We use null hypersurface techniques in a new approach to calculate the retarded waveform from a binary black hole merger in the close approximation. The process of removing ingoing radiation from the system leads to two notable features in the shape of the close approximation waveform for a head-on collision of black holes: (i) an initial quasinormal ringup and (ii) weak sensitivity to the parameter controlling the collision velocity. Feature (ii) is unexpected and has the potential importance of enabling the design of an efficient template for extracting the gravitational wave signal from the noise. |
1512.05865 | Daiske Yoshida | Daiske Yoshida, Jiro Soda | Quasi-Normal Modes of Black Holes in Lovelock Gravity | 20 pages, 27 figures | Phys. Rev. D 93, 044024 (2016) | 10.1103/PhysRevD.93.044024 | KOBE-TH-15-14 | gr-qc astro-ph.IM hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study quasinormal modes of black holes in Lovelock gravity. We formulate
the WKB method adapted to Lovelock gravity for the calculation of quasinormal
frequencies (QNFs). As a demonstration, we calculate various QNFs of Lovelock
black holes in seven and eight dimensions. We find that the QNFs show
remarkable features depending on the coefficients of the Lovelock terms, the
species of perturbations, and spacetime dimensions. In the case of the scalar
field, when we increase the coefficient of the third order Lovelock term, the
real part of QNFs increases, but the decay rate becomes small irrespective of
the mass of the black hole. For small black holes, the decay rate ceases to
depend on the Gauss-Bonnet term. In the case of tensor type perturbations of
the metric field, the tendency of the real part of QNFs is opposite to that of
the scalar field. The QNFs of vector type perturbations of the metric show no
particular behavior. The behavior of QNFs of the scalar type perturbations of
the metric field is similar to the vector type. However, available data are
rather sparse, which indicates that the WKB method is not applicable to many
models for this sector.
| [
{
"created": "Fri, 18 Dec 2015 07:30:45 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Feb 2016 17:37:32 GMT",
"version": "v2"
}
] | 2016-02-10 | [
[
"Yoshida",
"Daiske",
""
],
[
"Soda",
"Jiro",
""
]
] | We study quasinormal modes of black holes in Lovelock gravity. We formulate the WKB method adapted to Lovelock gravity for the calculation of quasinormal frequencies (QNFs). As a demonstration, we calculate various QNFs of Lovelock black holes in seven and eight dimensions. We find that the QNFs show remarkable features depending on the coefficients of the Lovelock terms, the species of perturbations, and spacetime dimensions. In the case of the scalar field, when we increase the coefficient of the third order Lovelock term, the real part of QNFs increases, but the decay rate becomes small irrespective of the mass of the black hole. For small black holes, the decay rate ceases to depend on the Gauss-Bonnet term. In the case of tensor type perturbations of the metric field, the tendency of the real part of QNFs is opposite to that of the scalar field. The QNFs of vector type perturbations of the metric show no particular behavior. The behavior of QNFs of the scalar type perturbations of the metric field is similar to the vector type. However, available data are rather sparse, which indicates that the WKB method is not applicable to many models for this sector. |
2209.01928 | Jo\~ao Lu\'is Rosa | D. Bazeia, A. S. Lob\~ao Jr., Jo\~ao Lu\'is Rosa | Multi-kink braneworld configurations in the scalar-tensor representation
of $f(R,T)$ gravity | 10 pages, 12 figures | European Physical Journal Plus 137:999 (2022) | 10.1140/epjp/s13360-022-03178-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we investigate the $f(R,T)$ brane in the scalar-tensor
representation, where the solutions of the equations of motions for the source
field engender topological defects with two-kink profiles. We use the
first-order formalism to obtain analytical solutions for the source field of
the brane and analyze how these solutions modify the structure of the auxiliary
fields arising from the scalar-tensor representation of the theory. We found
that when the model engenders two-kink solutions, the auxiliary fields are
modified in order to allow for the appearance of an internal structure. In
addition, the stability potential and zero mode also have their internal
structure modified by two-kink solution.
| [
{
"created": "Mon, 5 Sep 2022 12:13:31 GMT",
"version": "v1"
}
] | 2022-09-08 | [
[
"Bazeia",
"D.",
""
],
[
"Lobão",
"A. S.",
"Jr."
],
[
"Rosa",
"João Luís",
""
]
] | In this work we investigate the $f(R,T)$ brane in the scalar-tensor representation, where the solutions of the equations of motions for the source field engender topological defects with two-kink profiles. We use the first-order formalism to obtain analytical solutions for the source field of the brane and analyze how these solutions modify the structure of the auxiliary fields arising from the scalar-tensor representation of the theory. We found that when the model engenders two-kink solutions, the auxiliary fields are modified in order to allow for the appearance of an internal structure. In addition, the stability potential and zero mode also have their internal structure modified by two-kink solution. |
gr-qc/0403095 | Alexander E. Shalyt-Margolin | Alex E. Shalyt-Margolin | The Density Matrix Deformation in Physics of the Early Universe and Some
of its Implications | 53 pages, Latex. To appear in "Progress in General Relativity and
Quantum Cosmology Research" | "Quantum Cosmology Research Trends. Horizons in World Physics,
Volume 246,p.p.49--91" (Nova Science Publishers, Inc., Hauppauge, NY,2005)} | null | null | gr-qc | null | In this paper a new approach to investigation of Quantum and Statistical
Mechanics of the Early Universe (Planck scale) - density matrix deformation -
is proposed. The deformation is understood as an extension of a particular
theory by inclusion of one or several additional parameters in such a way that
the initial theory appears in the limiting transition...
| [
{
"created": "Tue, 23 Mar 2004 15:50:41 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Nov 2005 10:11:45 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Shalyt-Margolin",
"Alex E.",
""
]
] | In this paper a new approach to investigation of Quantum and Statistical Mechanics of the Early Universe (Planck scale) - density matrix deformation - is proposed. The deformation is understood as an extension of a particular theory by inclusion of one or several additional parameters in such a way that the initial theory appears in the limiting transition... |
gr-qc/0407034 | Tomohiro Harada | Tomohiro Harada, Ken-ichi Nakao | Border of Spacetime | 4 pages, 1 figure, accepted for publication in Physical Review D,
typos corrected | Phys.Rev. D70 (2004) 041501 | 10.1103/PhysRevD.70.041501 | null | gr-qc hep-th | null | It is still uncertain whether the cosmic censorship conjecture is true or
not. To get a new insight into this issue, we propose the concept of the border
of spacetime as a generalization of the spacetime singularity and discuss its
visibility. The visible border, corresponding to the naked singularity, is not
only relevant to mathematical completeness of general relativity but also a
window into new physics in strongly curved spacetimes, which is in principle
observable.
| [
{
"created": "Thu, 8 Jul 2004 09:04:37 GMT",
"version": "v1"
},
{
"created": "Sun, 8 Aug 2004 02:11:19 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Harada",
"Tomohiro",
""
],
[
"Nakao",
"Ken-ichi",
""
]
] | It is still uncertain whether the cosmic censorship conjecture is true or not. To get a new insight into this issue, we propose the concept of the border of spacetime as a generalization of the spacetime singularity and discuss its visibility. The visible border, corresponding to the naked singularity, is not only relevant to mathematical completeness of general relativity but also a window into new physics in strongly curved spacetimes, which is in principle observable. |
1511.08048 | P. A. Gonzalez | P. A. Gonzalez, Marco Olivares and Yerko Vasquez | Bounded orbits for photons as a consequence of extra dimensions | Improved version; References added | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we study the geodesic structure for a geometry described by a
spherically symmetric four-dimensional solution embedded in a five-dimensional
space known as a brane-based spherically symmetric solution. Mainly, we have
found that the extra dimension contributes to the existence of bounded orbits
for the photons, such as planetary and circular stable orbits that have not
been observed for other geometries.
| [
{
"created": "Wed, 25 Nov 2015 13:06:39 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Apr 2017 16:17:34 GMT",
"version": "v2"
}
] | 2017-04-04 | [
[
"Gonzalez",
"P. A.",
""
],
[
"Olivares",
"Marco",
""
],
[
"Vasquez",
"Yerko",
""
]
] | In this work, we study the geodesic structure for a geometry described by a spherically symmetric four-dimensional solution embedded in a five-dimensional space known as a brane-based spherically symmetric solution. Mainly, we have found that the extra dimension contributes to the existence of bounded orbits for the photons, such as planetary and circular stable orbits that have not been observed for other geometries. |
1611.04343 | Nematollah Riazi | S.N. Sajadi, N. Riazi | Gravitational Lensing by Polytropic Wormholes | 19 pages,11 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain static multi-polytropic wormhole solutions in the framework of GR
gravity. The resulting metric is asymptotically Minkowskian, and locally that
of a wormhole. We also examine gravitational lensing by the wormhole, and
calculate the deflection angle for weak and strong field limits. We investigate
microlensing in the weak field limit and obtain corresponding light curves for
both galactic and extragalactic situations. We discuss the multi-polytropic
equation of state for the energy-momentum tensor which supports this geometry
and finally, we check for the satisfaction of the weak energy condition.
| [
{
"created": "Mon, 14 Nov 2016 11:26:54 GMT",
"version": "v1"
},
{
"created": "Sat, 13 Jan 2018 11:30:20 GMT",
"version": "v2"
}
] | 2018-01-16 | [
[
"Sajadi",
"S. N.",
""
],
[
"Riazi",
"N.",
""
]
] | We obtain static multi-polytropic wormhole solutions in the framework of GR gravity. The resulting metric is asymptotically Minkowskian, and locally that of a wormhole. We also examine gravitational lensing by the wormhole, and calculate the deflection angle for weak and strong field limits. We investigate microlensing in the weak field limit and obtain corresponding light curves for both galactic and extragalactic situations. We discuss the multi-polytropic equation of state for the energy-momentum tensor which supports this geometry and finally, we check for the satisfaction of the weak energy condition. |
0804.0541 | Marco Pizzi | A. Paolino, M. Pizzi | Electric force lines of the double Reissner-Nordstrom exact solution | 19 pages, 7 figures, accepted by IJMPD | Int.J.Mod.Phys.D17:1159-1177,2008 | 10.1142/S0218271808012577 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, Alekseev and Belinski have presented a new exact solution of the
Einstein-Maxwell equations which describes two Reissner-Nordstrom (RN) sources
in reciprocal equilibrium (no struts nor strings); one source is a naked
singularity, the other is a black hole: this is the only possible configuration
for separable object, apart from the well-known extreme case ($m_i=e_i$).
In the present paper, after a brief summary of this solution, we study in
some detail the coordinate systems used and the main features of the
gravitational and electric fields. In particular we graph the plots of the
electric force lines in three qualitatively different situations: equal-signed
charges, opposite charges and the case of a naked singularity near a neutral
black hole.
| [
{
"created": "Thu, 3 Apr 2008 12:42:16 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Apr 2008 13:13:32 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Paolino",
"A.",
""
],
[
"Pizzi",
"M.",
""
]
] | Recently, Alekseev and Belinski have presented a new exact solution of the Einstein-Maxwell equations which describes two Reissner-Nordstrom (RN) sources in reciprocal equilibrium (no struts nor strings); one source is a naked singularity, the other is a black hole: this is the only possible configuration for separable object, apart from the well-known extreme case ($m_i=e_i$). In the present paper, after a brief summary of this solution, we study in some detail the coordinate systems used and the main features of the gravitational and electric fields. In particular we graph the plots of the electric force lines in three qualitatively different situations: equal-signed charges, opposite charges and the case of a naked singularity near a neutral black hole. |
0709.3152 | Brien C. Nolan | Brien C. Nolan, Ujjal Debnath | Is the shell-focusing singularity of Szekeres space-time visible? | 10 pages | Phys.Rev.D76:104046,2007 | 10.1103/PhysRevD.76.104046 | null | gr-qc | null | The visibility of the shell-focusing singularity in Szekeres space-time -
which represents quasi-spherical dust collapse - has been studied on numerous
occasions in the context of the cosmic censorship conjecture. The various
results derived have assumed that there exist radial null geodesics in the
space-time. We show that such geodesics do not exist in general, and so
previous results on the visibility of the singularity are not generally valid.
More precisely, we show that the existence of a radial geodesic in Szekeres
space-time implies that the space-time is axially symmetric, with the geodesic
along the polar direction (i.e. along the axis of symmetry). If there is a
second non-parallel radial geodesic, then the space-time is spherically
symmetric, and so is a Lema\^{\i}tre-Tolman-Bondi (LTB) space-time. For the
case of the polar geodesic in an axially symmetric Szekeres space-time, we give
conditions on the free functions (i.e. initial data) of the space-time which
lead to visibility of the singularity along this direction. Likewise, we give a
sufficient condition for censorship of the singularity. We point out the
complications involved in addressing the question of visibility of the
singularity both for non-radial null geodesics in the axially symmetric case
and in the general (non-axially symmetric) case, and suggest a possible
approach.
| [
{
"created": "Thu, 20 Sep 2007 08:18:42 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Nolan",
"Brien C.",
""
],
[
"Debnath",
"Ujjal",
""
]
] | The visibility of the shell-focusing singularity in Szekeres space-time - which represents quasi-spherical dust collapse - has been studied on numerous occasions in the context of the cosmic censorship conjecture. The various results derived have assumed that there exist radial null geodesics in the space-time. We show that such geodesics do not exist in general, and so previous results on the visibility of the singularity are not generally valid. More precisely, we show that the existence of a radial geodesic in Szekeres space-time implies that the space-time is axially symmetric, with the geodesic along the polar direction (i.e. along the axis of symmetry). If there is a second non-parallel radial geodesic, then the space-time is spherically symmetric, and so is a Lema\^{\i}tre-Tolman-Bondi (LTB) space-time. For the case of the polar geodesic in an axially symmetric Szekeres space-time, we give conditions on the free functions (i.e. initial data) of the space-time which lead to visibility of the singularity along this direction. Likewise, we give a sufficient condition for censorship of the singularity. We point out the complications involved in addressing the question of visibility of the singularity both for non-radial null geodesics in the axially symmetric case and in the general (non-axially symmetric) case, and suggest a possible approach. |
1612.08419 | Jeffrey Groah Ph.D. | Jeffrey M Groah | $C^{1,1}$ Pseudohermitian, Torsion-free Manifolds | 5 pages. arXiv admin note: text overlap with arXiv:1510.08078 | null | null | null | gr-qc math-ph math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Riemannian Manifolds may be $C^{1,1}$ and the geometry of these manifolds is
investigated in \cite{Groah1}. Here, a similar analysis is given for
pseudohermitian, torsion-free manifolds whereby, instead of assuming that the
metric is parallel, it is assumed that the metric is pseudohermitian, a
condition adopted by Einstein and elaborated upon in \cite{Hlavaty}. At the
level of regularity assumed here, Einstein's formulation of the pseudohermitian
condition is not tensorial and so a reformulation of this condition is given
here. It is shown that a $C^{1,1}$ manifold is pseudohermitian and torsion-free
if and only if it is Riemannian.
| [
{
"created": "Mon, 26 Dec 2016 18:17:24 GMT",
"version": "v1"
}
] | 2016-12-28 | [
[
"Groah",
"Jeffrey M",
""
]
] | Riemannian Manifolds may be $C^{1,1}$ and the geometry of these manifolds is investigated in \cite{Groah1}. Here, a similar analysis is given for pseudohermitian, torsion-free manifolds whereby, instead of assuming that the metric is parallel, it is assumed that the metric is pseudohermitian, a condition adopted by Einstein and elaborated upon in \cite{Hlavaty}. At the level of regularity assumed here, Einstein's formulation of the pseudohermitian condition is not tensorial and so a reformulation of this condition is given here. It is shown that a $C^{1,1}$ manifold is pseudohermitian and torsion-free if and only if it is Riemannian. |
gr-qc/9412002 | Maria Bento | M. C. Bento and O. Bertolami | Scale Factor Duality: A Quantum Cosmological Approach | 10 pages, plain tex, uses panda.tex (appended) | Class.Quant.Grav.12:1919-1926,1995 | 10.1088/0264-9381/12/8/009 | CERN-TH.7488/94, DFTT 43/94 | gr-qc | null | We consider the minisuperspace model arising from the lowest order string
effective action containing the graviton and the dilaton and study solutions of
the resulting Wheeler-Dewitt equation. The scale factor duality symmetry is
discussed in the context of our quantum cosmological model.
| [
{
"created": "Thu, 1 Dec 1994 16:59:02 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Bento",
"M. C.",
""
],
[
"Bertolami",
"O.",
""
]
] | We consider the minisuperspace model arising from the lowest order string effective action containing the graviton and the dilaton and study solutions of the resulting Wheeler-Dewitt equation. The scale factor duality symmetry is discussed in the context of our quantum cosmological model. |
2009.07681 | Ming Zhang | Ming Zhang and Jie Jiang | New gedanken experiment on higher-dimensional asymptotically AdS
Reissner-Nordstr\"om black hole | 7 pages, EPJC accepted | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | Viewing the negative cosmological constant as a dynamical quantity derived
from the matter field, we study the weak cosmic censorship conjecture for the
higher-dimensional asymptotically AdS Reissner-Nordstr\"om black hole. To this
end, using stability assumption of matter field perturbation and null energy
condition of the matter field, we first derive the first-order and second-order
perturbation inequalities containing the variable cosmological constant and its
conjugated quantity for the black hole . We prove that the higher-dimensional
RN-AdS black hole cannot be destroyed under a second-order approximation of the
matter field perturbation process.
| [
{
"created": "Wed, 16 Sep 2020 13:40:19 GMT",
"version": "v1"
}
] | 2020-09-17 | [
[
"Zhang",
"Ming",
""
],
[
"Jiang",
"Jie",
""
]
] | Viewing the negative cosmological constant as a dynamical quantity derived from the matter field, we study the weak cosmic censorship conjecture for the higher-dimensional asymptotically AdS Reissner-Nordstr\"om black hole. To this end, using stability assumption of matter field perturbation and null energy condition of the matter field, we first derive the first-order and second-order perturbation inequalities containing the variable cosmological constant and its conjugated quantity for the black hole . We prove that the higher-dimensional RN-AdS black hole cannot be destroyed under a second-order approximation of the matter field perturbation process. |
2209.00874 | Carlos Albertho Benavides-Gallego | Carlos A. Benavides-Gallego and Wen-Biao Han | Gravitational waves and electromagnetic radiation from charged black
hole binaries | 24 pages, 7 figures | Symmetry 2023, 15(2), 537; | 10.3390/sym15020537 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | It is still an open issue if astrophysical black holes have electric charges
or not. In this work, we analytically calculate gravitational and
electromagnetic waveforms in the frequency domain for charged black hole
binaries during the inspiral phase. In addition to the well-known $f^{-7/6}$
waveforms, we also get a $-11/6$ power law gravitational wave component. The
phase of waveforms for charged binary is fully derived. In the case of
electromagnetic counterparts, we focus on the electromagnetic dipole radiation,
but we include the quadrupole contribution to complete our discussion. We also
obtain the chirp property of the electromagnetic waves. In the case of dipole
radiation, the frequency-domain waves are proportional to $f^{-7/6}$, while
$f^{-1/6}$ appears in the quadrupole contribution. The frequency-domain
waveforms can be used to estimate the charges of black holes in the current
gravitational wave observations.
| [
{
"created": "Fri, 2 Sep 2022 08:23:01 GMT",
"version": "v1"
}
] | 2023-02-21 | [
[
"Benavides-Gallego",
"Carlos A.",
""
],
[
"Han",
"Wen-Biao",
""
]
] | It is still an open issue if astrophysical black holes have electric charges or not. In this work, we analytically calculate gravitational and electromagnetic waveforms in the frequency domain for charged black hole binaries during the inspiral phase. In addition to the well-known $f^{-7/6}$ waveforms, we also get a $-11/6$ power law gravitational wave component. The phase of waveforms for charged binary is fully derived. In the case of electromagnetic counterparts, we focus on the electromagnetic dipole radiation, but we include the quadrupole contribution to complete our discussion. We also obtain the chirp property of the electromagnetic waves. In the case of dipole radiation, the frequency-domain waves are proportional to $f^{-7/6}$, while $f^{-1/6}$ appears in the quadrupole contribution. The frequency-domain waveforms can be used to estimate the charges of black holes in the current gravitational wave observations. |
1405.0638 | Stanley P. Gudder | Stan Gudder | The Universe as a Quantum Computer | 23 pages, 1 figure | Axioms 2015; 4(1): 102-119 | 10.3390/axioms4010102 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article presents a sequential growth model for the universe that acts
like a quantum computer. The basic constituents of the model are a special type
of causal set (causet) called a $c$-causet. A $c$-causet is defined to be a
causet that is independent of its labeling. We characterize $c$-causets as
those causets that form a multipartite graph or equivalently those causets
whose elements are comparable whenever their heights are different. We show
that a $c$-causet has precisely two $c$-causet offspring. It follows that there
are $2^n$ $c$-causets of cardinality $n+1$. This enables us to classify
$c$-causets of cardinality $n+1$ in terms of $n$-bits. We then quantize the
model by introducing a quantum sequential growth process. This is accomplished
by replacing the $n$-bits by $n$-qubits and defining transition amplitudes for
the growth transitions. We mainly consider two types of processes called
stationary and completely stationary. We show that for stationary processes,
the probability operators are tensor products of positive rank-1 qubit
operators. Moreover, the converse of this result holds. Simplifications occur
for completely stationary processes. We close with examples of precluded
events.
| [
{
"created": "Sun, 4 May 2014 01:04:24 GMT",
"version": "v1"
}
] | 2022-09-01 | [
[
"Gudder",
"Stan",
""
]
] | This article presents a sequential growth model for the universe that acts like a quantum computer. The basic constituents of the model are a special type of causal set (causet) called a $c$-causet. A $c$-causet is defined to be a causet that is independent of its labeling. We characterize $c$-causets as those causets that form a multipartite graph or equivalently those causets whose elements are comparable whenever their heights are different. We show that a $c$-causet has precisely two $c$-causet offspring. It follows that there are $2^n$ $c$-causets of cardinality $n+1$. This enables us to classify $c$-causets of cardinality $n+1$ in terms of $n$-bits. We then quantize the model by introducing a quantum sequential growth process. This is accomplished by replacing the $n$-bits by $n$-qubits and defining transition amplitudes for the growth transitions. We mainly consider two types of processes called stationary and completely stationary. We show that for stationary processes, the probability operators are tensor products of positive rank-1 qubit operators. Moreover, the converse of this result holds. Simplifications occur for completely stationary processes. We close with examples of precluded events. |
2004.02858 | Wen-Yuan Ai | Wen-Yuan Ai | A note on the novel 4D Einstein-Gauss-Bonnet gravity | 9 pages, revtex format; v2: references added; v3: minor typos
corrected, an appendix added, to match the published version | Commun. Theor. Phys. 72 (2020) 095402 | 10.1088/1572-9494/aba242 | CP3-20-16 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, a novel 4D Einstein-Gauss-Bonnet gravity has been proposed by
Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)] by rescaling the coupling
$\alpha \rightarrow \alpha/(D-4)$ and taking the limit $D\rightarrow 4$ at the
level of equations of motion. This prescription, though was shown to bring
non-trivial effects for some spacetimes with particular symmetries, remains
mysterious and calls for scrutiny. Indeed, there is no continuous way to take
the limit $D\rightarrow 4$ in the higher $D$-dimensional equations of motion
because the tensor indices depend on the spacetime dimension and behave
discretely. On the other hand, if one works with four-dimensional spacetime
indices the contribution corresponding to the Gauss-Bonnet term vanishes
identically in the equations of motion. A necessary condition (but may not be
sufficient) for this procedure to work is that there is an embedding of the
four-dimensional spacetime into the higher $D$-dimensional spacetime so that
the equations in the latter can be properly interpreted after taking the limit.
In this note, working with 2D Einstein gravity, we show several subtleties when
applying the method used in [Phys. Rev. Lett. 124, 081301 (2020)].
| [
{
"created": "Mon, 6 Apr 2020 17:49:24 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Apr 2020 16:06:51 GMT",
"version": "v2"
},
{
"created": "Wed, 5 Aug 2020 15:25:40 GMT",
"version": "v3"
}
] | 2020-08-06 | [
[
"Ai",
"Wen-Yuan",
""
]
] | Recently, a novel 4D Einstein-Gauss-Bonnet gravity has been proposed by Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)] by rescaling the coupling $\alpha \rightarrow \alpha/(D-4)$ and taking the limit $D\rightarrow 4$ at the level of equations of motion. This prescription, though was shown to bring non-trivial effects for some spacetimes with particular symmetries, remains mysterious and calls for scrutiny. Indeed, there is no continuous way to take the limit $D\rightarrow 4$ in the higher $D$-dimensional equations of motion because the tensor indices depend on the spacetime dimension and behave discretely. On the other hand, if one works with four-dimensional spacetime indices the contribution corresponding to the Gauss-Bonnet term vanishes identically in the equations of motion. A necessary condition (but may not be sufficient) for this procedure to work is that there is an embedding of the four-dimensional spacetime into the higher $D$-dimensional spacetime so that the equations in the latter can be properly interpreted after taking the limit. In this note, working with 2D Einstein gravity, we show several subtleties when applying the method used in [Phys. Rev. Lett. 124, 081301 (2020)]. |
1807.00768 | Bob Osano | Bob Osano and Timothy Oreta | Multi-fluid Theory and Cosmology: A Convective Variational Approach to
Interacting Dark-Sector | 10 pages. This article builds on the foundational work presented by
the authors of arXiv:gr-qc/0605010 | null | 10.1142/S0218271819500780 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article examines the foundation of the recently developed relativistic
variational formalism[1]. Our work is heavily based on [2, 27] which extends
this approach to the multi-fluid theory and examines its utility in
astrophysics and cosmology. Unlike the extension to the formalism mentioned
above, that looks at the general interaction between different types of matter,
we use the formalism to examine the interaction involving, ordinary matter,
dark matter (DM) and dark energy (DE). We focus on entrainment phenomena
involving the dark-sector constituents.
| [
{
"created": "Mon, 2 Jul 2018 16:06:18 GMT",
"version": "v1"
},
{
"created": "Tue, 31 Jul 2018 20:44:58 GMT",
"version": "v2"
}
] | 2019-05-22 | [
[
"Osano",
"Bob",
""
],
[
"Oreta",
"Timothy",
""
]
] | This article examines the foundation of the recently developed relativistic variational formalism[1]. Our work is heavily based on [2, 27] which extends this approach to the multi-fluid theory and examines its utility in astrophysics and cosmology. Unlike the extension to the formalism mentioned above, that looks at the general interaction between different types of matter, we use the formalism to examine the interaction involving, ordinary matter, dark matter (DM) and dark energy (DE). We focus on entrainment phenomena involving the dark-sector constituents. |
gr-qc/9808019 | Jerzy Matyjasek | Jerzy Matyjasek | $<T^{\mu}_{\nu}>_{ren}$ of the quantized fields in the Unruh state in
the Schwarzschild spacetime | 17 pages, REVTEX | Phys. Rev. D 59, 044002 (1999) | 10.1103/PhysRevD.59.044002 | UMCS-FM-98-16 | gr-qc | null | The renormalized expectation value of the stress energy tensor of the
conformally invariant massless fields in the Unruh state in the Schwarzschild
spacetime is constructed. It is achieved through solving the conservation
equation in conformal space and utilizing the regularity conditions in the
physical metric. The relations of obtained results to the existing
approximations are analysed.
| [
{
"created": "Thu, 6 Aug 1998 17:14:28 GMT",
"version": "v1"
}
] | 2016-08-25 | [
[
"Matyjasek",
"Jerzy",
""
]
] | The renormalized expectation value of the stress energy tensor of the conformally invariant massless fields in the Unruh state in the Schwarzschild spacetime is constructed. It is achieved through solving the conservation equation in conformal space and utilizing the regularity conditions in the physical metric. The relations of obtained results to the existing approximations are analysed. |
2101.06347 | Celia Escamilla-Rivera | Geovanny A. Rave-Franco, Celia Escamilla-Rivera and Jackson Levi Said | Dynamical complexity of the Teleparallel gravity cosmology | 19 pages, 4 figures | Phys. Rev. D 103, 084017 (2021) | 10.1103/PhysRevD.103.084017 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The exploration of teleparallel gravity has been done from a dynamical
systems point of view in order to be tested against the cosmological evolution
currently observed. So far, the proposed autonomous systems have been
restrictive over a constant dynamical variable, which contains information
related to the dynamics on the $H_0$ value. It is therefore that in this paper
we consider a generalization of the dynamical system by imposing a nonconstant
degree of freedom over it which allows us to rewrite a generic autonomous
dynamical analysis. We describe the treatment of our nonlinear autonomous
system by studying the hyperbolic critical points and discuss an interesting
phenomenological feature in regards to $H_0$: the possibility to obtain a
best-fit value for this parameter in a cosmologically viable $f(T,B)$ model, a
mixed power law. This result allows us to present a generic scenario in which
it is possible to fix constraints to solve the $H_0$ tension at late times
where its linearized solutions are considered.
| [
{
"created": "Sat, 16 Jan 2021 01:56:33 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Apr 2021 23:24:00 GMT",
"version": "v2"
}
] | 2021-04-15 | [
[
"Rave-Franco",
"Geovanny A.",
""
],
[
"Escamilla-Rivera",
"Celia",
""
],
[
"Said",
"Jackson Levi",
""
]
] | The exploration of teleparallel gravity has been done from a dynamical systems point of view in order to be tested against the cosmological evolution currently observed. So far, the proposed autonomous systems have been restrictive over a constant dynamical variable, which contains information related to the dynamics on the $H_0$ value. It is therefore that in this paper we consider a generalization of the dynamical system by imposing a nonconstant degree of freedom over it which allows us to rewrite a generic autonomous dynamical analysis. We describe the treatment of our nonlinear autonomous system by studying the hyperbolic critical points and discuss an interesting phenomenological feature in regards to $H_0$: the possibility to obtain a best-fit value for this parameter in a cosmologically viable $f(T,B)$ model, a mixed power law. This result allows us to present a generic scenario in which it is possible to fix constraints to solve the $H_0$ tension at late times where its linearized solutions are considered. |
gr-qc/9602038 | Takahiro Tanaka | Takahiro Tanaka, Yasushi Mino, Misao Sasaki and Masaru Shibata | Gravitational waves from a spinning particle in circular orbits around a
rotating black hole | 20 pages, LaTeX, 2 figures available upon request | Phys.Rev.D54:3762-3777,1996 | 10.1103/PhysRevD.54.3762 | OU-TAP-27 | gr-qc | null | Using the Teukolsky and Sasaki-Nakamura formalisms for the perterbations
around a Kerr black hole, we calculate the energy flux of gravitational waves
induced by a {\it spinning} particle of mass $\mu$ and spin $S$ moving in
circular orbits near the equatorial plain of a rotating black hole of mass $M
(\gg \mu)$ and spin $Ma$. The calculations are performed by using the recently
developed post-Newtonian expansion technique of the Teukolsky equation. To
evaluate the source terms of perturbations caused by a {\it spinning} particle,
we used the equations of motion of a spinning particle derived by Papapetrou
and the energy momentum tensor of a spinning particle derived by Dixon. We
present the post-Newtonian formula of the gravitational wave luminosity up to
the order $(v/c)^5$ beyond the quadrupole formula including the linear order of
particle spin. The results obtained in this paper will be an important
guideline to the post-Newtonian calculation of the inspiral of two spinning
compact objects.
| [
{
"created": "Mon, 19 Feb 1996 12:13:46 GMT",
"version": "v1"
}
] | 2009-10-09 | [
[
"Tanaka",
"Takahiro",
""
],
[
"Mino",
"Yasushi",
""
],
[
"Sasaki",
"Misao",
""
],
[
"Shibata",
"Masaru",
""
]
] | Using the Teukolsky and Sasaki-Nakamura formalisms for the perterbations around a Kerr black hole, we calculate the energy flux of gravitational waves induced by a {\it spinning} particle of mass $\mu$ and spin $S$ moving in circular orbits near the equatorial plain of a rotating black hole of mass $M (\gg \mu)$ and spin $Ma$. The calculations are performed by using the recently developed post-Newtonian expansion technique of the Teukolsky equation. To evaluate the source terms of perturbations caused by a {\it spinning} particle, we used the equations of motion of a spinning particle derived by Papapetrou and the energy momentum tensor of a spinning particle derived by Dixon. We present the post-Newtonian formula of the gravitational wave luminosity up to the order $(v/c)^5$ beyond the quadrupole formula including the linear order of particle spin. The results obtained in this paper will be an important guideline to the post-Newtonian calculation of the inspiral of two spinning compact objects. |
1811.00065 | Tousif Islam | Tousif Islam | Globular clusters as a probe for Weyl Conformal Gravity | 11 pages, 8 figures, Accepted for publication in MNRAS, to appear in
the given DOI | null | 10.1093/mnras/stz2090 | null | gr-qc astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Eventual flattening of velocity dispersion profiles of some galactic globular
clusters in the Milky Way cannot be explained in the framework of Newtonian
gravity and hence in general theory of relativity in the weak field limit,
without resorting to the occurrence of tidal effects. We explore the
possibility of explaining such deviation from expected Keplerian fall-off in
dispersion profiles within the context of Weyl conformal gravity. We choose a
set of 20 globular clusters for which recent kinematic measurements are
available. We model the globular clusters with approximate Hernquist mass
profiles and choose a constant mass-to-light ratio throughout the cluster as
the only free parameter in the model. Our analysis finds reasonable Weyl
gravity fits to the observed dispersion profiles, exhibiting both Keplerian
decline and eventual flattening, with acceptable mass-to-light ratios. We
further recover a Tully-Fisher like scaling relation in globular clusters
through Weyl gravity.
| [
{
"created": "Wed, 31 Oct 2018 18:58:21 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Jul 2019 20:28:03 GMT",
"version": "v2"
}
] | 2019-07-31 | [
[
"Islam",
"Tousif",
""
]
] | Eventual flattening of velocity dispersion profiles of some galactic globular clusters in the Milky Way cannot be explained in the framework of Newtonian gravity and hence in general theory of relativity in the weak field limit, without resorting to the occurrence of tidal effects. We explore the possibility of explaining such deviation from expected Keplerian fall-off in dispersion profiles within the context of Weyl conformal gravity. We choose a set of 20 globular clusters for which recent kinematic measurements are available. We model the globular clusters with approximate Hernquist mass profiles and choose a constant mass-to-light ratio throughout the cluster as the only free parameter in the model. Our analysis finds reasonable Weyl gravity fits to the observed dispersion profiles, exhibiting both Keplerian decline and eventual flattening, with acceptable mass-to-light ratios. We further recover a Tully-Fisher like scaling relation in globular clusters through Weyl gravity. |
gr-qc/0302083 | Carlos Palenzuela | C. Bona, T. Ledvinka, C. Palenzuela and M. Zacek | General-covariant evolution formalism for Numerical Relativity | null | Phys.Rev.D67:104005,2003 | 10.1103/PhysRevD.67.104005 | null | gr-qc | null | A general covariant extension of Einstein\'{}s field equations is considered
with a view to Numerical Relativity applications. The basic variables are taken
to be the metric tensor and an additional four-vector $Z_\mu$. Einstein's
solutions are recovered when the additional four-vector vanishes, so that the
energy and momentum constraints amount to the covariant algebraic condition
$Z_\mu=0$. The extended field equations can be supplemented by suitable
coordinate conditions in order to provide symmetric hyperbolic evolution
systems: this is actually the case for either harmonic coordinates or normal
coordinates with harmonic slicing.
| [
{
"created": "Thu, 20 Feb 2003 09:33:45 GMT",
"version": "v1"
}
] | 2011-04-21 | [
[
"Bona",
"C.",
""
],
[
"Ledvinka",
"T.",
""
],
[
"Palenzuela",
"C.",
""
],
[
"Zacek",
"M.",
""
]
] | A general covariant extension of Einstein\'{}s field equations is considered with a view to Numerical Relativity applications. The basic variables are taken to be the metric tensor and an additional four-vector $Z_\mu$. Einstein's solutions are recovered when the additional four-vector vanishes, so that the energy and momentum constraints amount to the covariant algebraic condition $Z_\mu=0$. The extended field equations can be supplemented by suitable coordinate conditions in order to provide symmetric hyperbolic evolution systems: this is actually the case for either harmonic coordinates or normal coordinates with harmonic slicing. |
1310.5853 | Roberto Casadio | Roberto Casadio, Jorge Ovalle, Roldao da Rocha | Black Strings from Minimal Geometric Deformation in a Variable Tension
Brane-World | 20 pages, 6 figures | Class.Quant.Grav. 31 (2014) 045016 | 10.1088/0264-9381/31/4/045016 | null | gr-qc astro-ph.CO astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study brane-world models with variable brane tension and compute
corrections to the horizon of a black string along the extra dimension. The
four-dimensional geometry of the black string on the brane is obtained by means
of the minimal geometric deformation approach, and the bulk corrections are
then encoded in additional terms involving the covariant derivatives of the
variable brane tension. Our investigation shows that the variable brane tension
strongly affects the shape and evolution of the black string horizon along the
extra dimension, at least in a near-brane expansion. In particular, we apply
our general analysis to a model motivated by the E\"otv\"os branes, where the
variable brane tension is related to the Friedmann-Robertson-Walker brane-world
cosmology. We show that for some stages in the evolution of the universe, the
black string warped horizon collapses to a point and the black string has
correspondingly finite extent along the extra dimension. Furthermore, we show
that in the minimal geometric deformation of a black hole on the variable
tension brane, the black string has a throat along the extra dimension, whose
area tends to zero as time goes to infinity.
| [
{
"created": "Tue, 22 Oct 2013 09:30:10 GMT",
"version": "v1"
}
] | 2015-01-21 | [
[
"Casadio",
"Roberto",
""
],
[
"Ovalle",
"Jorge",
""
],
[
"da Rocha",
"Roldao",
""
]
] | We study brane-world models with variable brane tension and compute corrections to the horizon of a black string along the extra dimension. The four-dimensional geometry of the black string on the brane is obtained by means of the minimal geometric deformation approach, and the bulk corrections are then encoded in additional terms involving the covariant derivatives of the variable brane tension. Our investigation shows that the variable brane tension strongly affects the shape and evolution of the black string horizon along the extra dimension, at least in a near-brane expansion. In particular, we apply our general analysis to a model motivated by the E\"otv\"os branes, where the variable brane tension is related to the Friedmann-Robertson-Walker brane-world cosmology. We show that for some stages in the evolution of the universe, the black string warped horizon collapses to a point and the black string has correspondingly finite extent along the extra dimension. Furthermore, we show that in the minimal geometric deformation of a black hole on the variable tension brane, the black string has a throat along the extra dimension, whose area tends to zero as time goes to infinity. |
1609.02219 | Nelson Yokomizo | Eugenio Bianchi, Jonathan Guglielmon, Lucas Hackl, Nelson Yokomizo | Loop expansion and the bosonic representation of loop quantum gravity | 33 pages, 2 figures | Phys. Rev. D 94, 086009 (2016) | 10.1103/PhysRevD.94.086009 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce a new loop expansion that provides a resolution of the identity
in the Hilbert space of loop quantum gravity on a fixed graph. We work in the
bosonic representation obtained by the canonical quantization of the spinorial
formalism. The resolution of the identity gives a tool for implementing the
projection of states in the full bosonic representation onto the space of
solutions to the Gauss and area matching constraints of loop quantum gravity.
This procedure is particularly efficient in the semiclassical regime, leading
to explicit expressions for the loop expansions of coherent, heat kernel and
squeezed states.
| [
{
"created": "Wed, 7 Sep 2016 23:29:56 GMT",
"version": "v1"
}
] | 2016-11-02 | [
[
"Bianchi",
"Eugenio",
""
],
[
"Guglielmon",
"Jonathan",
""
],
[
"Hackl",
"Lucas",
""
],
[
"Yokomizo",
"Nelson",
""
]
] | We introduce a new loop expansion that provides a resolution of the identity in the Hilbert space of loop quantum gravity on a fixed graph. We work in the bosonic representation obtained by the canonical quantization of the spinorial formalism. The resolution of the identity gives a tool for implementing the projection of states in the full bosonic representation onto the space of solutions to the Gauss and area matching constraints of loop quantum gravity. This procedure is particularly efficient in the semiclassical regime, leading to explicit expressions for the loop expansions of coherent, heat kernel and squeezed states. |
2306.03880 | Andronikos Paliathanasis | Andronikos Paliathanasis | Dynamical analysis in Chameleon dark energy | 34 pages, 13 figures, to appear in Fortschritte der Physik (Progress
of Physics) | null | null | null | gr-qc hep-th math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | We present a detailed analysis of the phase-space for the field equations in
scalar field cosmology with a chameleon cosmology in a spatially flat
Friedmann--Lema\^{\i}tre--Robertson--Walker spacetime. For the matter source we
assume that it is an ideal gas with a constant equation of state parameter,
while for the scalar field potential and the coupling function of the chameleon
mechanism we consider four different sets which provide four different models.
We consider the $H$-normalization approach and we write the field equations
with the help of dimensionless variables. The asymptotic solutions are
determined from where we find that the theory can describe the main eras of
cosmological history and evolution. Future attractors which describe
acceleration exist, however we found past acceleration solutions related to the
inflationary era, as also the radiation epoch and the matter dominated eras are
provided by the dynamics. We conclude that the Chameleon dark energy model can
be used as a unified model for the elements which contribute to the dark sector
of the universe.
| [
{
"created": "Tue, 6 Jun 2023 17:31:04 GMT",
"version": "v1"
}
] | 2023-06-07 | [
[
"Paliathanasis",
"Andronikos",
""
]
] | We present a detailed analysis of the phase-space for the field equations in scalar field cosmology with a chameleon cosmology in a spatially flat Friedmann--Lema\^{\i}tre--Robertson--Walker spacetime. For the matter source we assume that it is an ideal gas with a constant equation of state parameter, while for the scalar field potential and the coupling function of the chameleon mechanism we consider four different sets which provide four different models. We consider the $H$-normalization approach and we write the field equations with the help of dimensionless variables. The asymptotic solutions are determined from where we find that the theory can describe the main eras of cosmological history and evolution. Future attractors which describe acceleration exist, however we found past acceleration solutions related to the inflationary era, as also the radiation epoch and the matter dominated eras are provided by the dynamics. We conclude that the Chameleon dark energy model can be used as a unified model for the elements which contribute to the dark sector of the universe. |
2405.19181 | Gustav Mogull | Alessandra Buonanno, Gustav Mogull, Raj Patil, Lorenzo Pompili | Post-Minkowskian Theory Meets the Spinning Effective-One-Body Approach
for Bound-Orbit Waveforms | 5 pages, 4 figures; supplemental material; attached ancillary
Mathematica file | null | null | HU-EP-24/16-RTG | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Driven by advances in scattering amplitudes and worldline-based methods,
recent years have seen significant progress in our ability to calculate
gravitational two-body scattering observables. These observables effectively
encapsulate the gravitational two-body problem in the weak-field and
high-velocity regime (post-Minkowskian, PM), with applications to the bound
two-body problem and gravitational-wave modeling. We leverage PM data to
construct a complete inspiral-merger-ringdown waveform model for non-precessing
spinning black holes within the effective-one-body (EOB) formalism: SEOBNR-PM.
This model is closely based on the highly successful SEOBNRv5 model, used by
the LIGO-Virgo-KAGRA Collaboration, with its key new feature being an EOB
Hamiltonian derived by matching the two-body scattering angle in a perturbative
PM expansion. The model performs remarkably well, showing a median mismatch
against 441 numerical-relativity (NR) simulations that is somewhat lower than a
similarly calibrated version of SEOBNRv5. Comparisons of the binding energy
with NR also demonstrate better agreement than SEOBNRv5, despite the latter
containing additional calibration to NR simulations.
| [
{
"created": "Wed, 29 May 2024 15:21:51 GMT",
"version": "v1"
}
] | 2024-05-30 | [
[
"Buonanno",
"Alessandra",
""
],
[
"Mogull",
"Gustav",
""
],
[
"Patil",
"Raj",
""
],
[
"Pompili",
"Lorenzo",
""
]
] | Driven by advances in scattering amplitudes and worldline-based methods, recent years have seen significant progress in our ability to calculate gravitational two-body scattering observables. These observables effectively encapsulate the gravitational two-body problem in the weak-field and high-velocity regime (post-Minkowskian, PM), with applications to the bound two-body problem and gravitational-wave modeling. We leverage PM data to construct a complete inspiral-merger-ringdown waveform model for non-precessing spinning black holes within the effective-one-body (EOB) formalism: SEOBNR-PM. This model is closely based on the highly successful SEOBNRv5 model, used by the LIGO-Virgo-KAGRA Collaboration, with its key new feature being an EOB Hamiltonian derived by matching the two-body scattering angle in a perturbative PM expansion. The model performs remarkably well, showing a median mismatch against 441 numerical-relativity (NR) simulations that is somewhat lower than a similarly calibrated version of SEOBNRv5. Comparisons of the binding energy with NR also demonstrate better agreement than SEOBNRv5, despite the latter containing additional calibration to NR simulations. |
1003.1309 | Mark D. Roberts | Mark D. Roberts | String theory explanation of galactic rotation | Note change in title from: Scalar-tensor explanation of galactic
rotation, to: String theory explanation of galactic rotation, was three and a
half pages, now is seven pages long | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The unique spherically symmetric metric which has vanishing weyl tensor, is
asymptotically desitter, and can model constant galactic rotation curves is
presented. Two types of field equations are shown to have this metric as an
exact solution. The first is palatini varied scalar-tensor theory. The second
is the low energy limit of string theory modified by inclusion of a contrived
potential.
| [
{
"created": "Fri, 5 Mar 2010 16:55:59 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Apr 2010 15:56:18 GMT",
"version": "v2"
}
] | 2010-04-14 | [
[
"Roberts",
"Mark D.",
""
]
] | The unique spherically symmetric metric which has vanishing weyl tensor, is asymptotically desitter, and can model constant galactic rotation curves is presented. Two types of field equations are shown to have this metric as an exact solution. The first is palatini varied scalar-tensor theory. The second is the low energy limit of string theory modified by inclusion of a contrived potential. |
2312.02507 | Yong Tang | Wen-Hao Wu, Yong Tang | Post-Newtonian Binary Dynamics in Effective Field Theory of Horndeski
Gravity | 1+22 pages, 9 figures | Chinese Physics C 48, 035101(2024) | 10.1088/1674-1137/ad1a0c | null | gr-qc astro-ph.CO hep-ph | http://creativecommons.org/licenses/by/4.0/ | General relativity has been very successful since its proposal more a century
ago. However, various cosmological observations and theoretical consistency
still motivate us to explore extended gravity theories. Horndeski gravity
stands out as one attractive theory by introducing only one scalar field. Here
we formulate the post-Newtonian effective field theory of Horndeski gravity and
investigate the conservative dynamics of the inspiral compact binary systems.
We calculate the leading effective Lagrangian for a compact binary and obtain
the periastron advance per period. In particular, we apply our analytical
calculation to two binary systems, PSR B 1534+12 and PSR J0737-3039, and
constrain the relevant model parameters. The theoretical framework can also be
extended to higher order systematically.
| [
{
"created": "Tue, 5 Dec 2023 05:23:00 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Feb 2024 08:39:59 GMT",
"version": "v2"
}
] | 2024-02-27 | [
[
"Wu",
"Wen-Hao",
""
],
[
"Tang",
"Yong",
""
]
] | General relativity has been very successful since its proposal more a century ago. However, various cosmological observations and theoretical consistency still motivate us to explore extended gravity theories. Horndeski gravity stands out as one attractive theory by introducing only one scalar field. Here we formulate the post-Newtonian effective field theory of Horndeski gravity and investigate the conservative dynamics of the inspiral compact binary systems. We calculate the leading effective Lagrangian for a compact binary and obtain the periastron advance per period. In particular, we apply our analytical calculation to two binary systems, PSR B 1534+12 and PSR J0737-3039, and constrain the relevant model parameters. The theoretical framework can also be extended to higher order systematically. |
0810.1680 | Dan Giang | Dan Giang, Charles C. Dyer | Velocity dominated singularities in the cheese slice universe | 11 pages, 3 figures, accepted for publication in the International
Journal of Modern Physics D | Int.J.Mod.Phys.D18:13-23,2009 | 10.1142/S0218271809014248 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the properties of spacetimes resulting from matching together
exact solutions using the Darmois matching conditions. In particular we focus
on the asymptotically velocity term dominated property (AVTD). We propose a
criterion that can be used to test if a spacetime constructed from a matching
can be considered AVTD. Using the Cheese Slice universe as an example, we show
that a spacetime constructed from a such a matching can inherit the AVTD
property from the original spacetimes. Furthermore the singularity resulting
from this particular matching is an AVTD singularity.
| [
{
"created": "Thu, 9 Oct 2008 15:55:04 GMT",
"version": "v1"
}
] | 2009-03-24 | [
[
"Giang",
"Dan",
""
],
[
"Dyer",
"Charles C.",
""
]
] | We investigate the properties of spacetimes resulting from matching together exact solutions using the Darmois matching conditions. In particular we focus on the asymptotically velocity term dominated property (AVTD). We propose a criterion that can be used to test if a spacetime constructed from a matching can be considered AVTD. Using the Cheese Slice universe as an example, we show that a spacetime constructed from a such a matching can inherit the AVTD property from the original spacetimes. Furthermore the singularity resulting from this particular matching is an AVTD singularity. |
2307.03155 | Tousif Islam | Tousif Islam and Gaurav Khanna | On the approximate relation between black-hole perturbation theory and
numerical relativity | 14 pages, 11 figures, Phys. Rev. D 108, 124046 | null | 10.1103/PhysRevD.108.124046 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the interplay between numerical relativity (NR) and adiabatic
point-particle black hole perturbation theory (ppBHPT) in the comparable mass
regime for quasi-circular non-spinning binary black holes. Specifically, we
reassess the $\alpha$-$\beta$ scaling technique, previously introduced by Islam
et al, as a means to effectively match ppBHPT waveforms to NR waveforms within
this regime. In particular, $\alpha$ rescales the amplitude and $\beta$
rescales the time (and hence the phase). Utilizing publicly available long NR
data (\texttt{SXS:BBH:2265}~\cite{sxs_collaboration_2019}) for a mass ratio of
$1:3$, encompassing the final $\sim 65$ orbital cycles of the binary evolution,
we examine the range of applicability of such scalings. We observe that the
scaling technique remains effective even during the earlier stages of the
inspiral. Additionally, we provide commentary on the temporal evolution of the
$\alpha$ and $\beta$ parameters and discuss whether they can be approximated as
constant values. Consequently, we derive the $\alpha$-$\beta$ scaling as a
function of orbital frequencies and demonstrate that it is equivalent to a
frequency-dependent correction. We further provide a brief comparison between
post-Newtonian (PN) waveforms and the rescaled ppBHPT waveform at a mass ratio
of $q=3$ and comment on their regime of validity. Finally, we explore the
possibility of using PN theory to obtain the $\alpha$-$\beta$ calibration
parameters and still provide a rescaled ppBHPT waveform that matches NR.
| [
{
"created": "Thu, 6 Jul 2023 17:30:43 GMT",
"version": "v1"
},
{
"created": "Sat, 3 Feb 2024 23:33:30 GMT",
"version": "v2"
}
] | 2024-02-06 | [
[
"Islam",
"Tousif",
""
],
[
"Khanna",
"Gaurav",
""
]
] | We investigate the interplay between numerical relativity (NR) and adiabatic point-particle black hole perturbation theory (ppBHPT) in the comparable mass regime for quasi-circular non-spinning binary black holes. Specifically, we reassess the $\alpha$-$\beta$ scaling technique, previously introduced by Islam et al, as a means to effectively match ppBHPT waveforms to NR waveforms within this regime. In particular, $\alpha$ rescales the amplitude and $\beta$ rescales the time (and hence the phase). Utilizing publicly available long NR data (\texttt{SXS:BBH:2265}~\cite{sxs_collaboration_2019}) for a mass ratio of $1:3$, encompassing the final $\sim 65$ orbital cycles of the binary evolution, we examine the range of applicability of such scalings. We observe that the scaling technique remains effective even during the earlier stages of the inspiral. Additionally, we provide commentary on the temporal evolution of the $\alpha$ and $\beta$ parameters and discuss whether they can be approximated as constant values. Consequently, we derive the $\alpha$-$\beta$ scaling as a function of orbital frequencies and demonstrate that it is equivalent to a frequency-dependent correction. We further provide a brief comparison between post-Newtonian (PN) waveforms and the rescaled ppBHPT waveform at a mass ratio of $q=3$ and comment on their regime of validity. Finally, we explore the possibility of using PN theory to obtain the $\alpha$-$\beta$ calibration parameters and still provide a rescaled ppBHPT waveform that matches NR. |
1311.5397 | Iver Brevik | I. Brevik, A. V. Timoshkin and Y. Rabochaya | Little Rip and Pseudo Rip Phenomena from Coupled Dark Energy | 11 pages, Latex2e, no figures. To appear in Modern Physics Letters A | Modern Physics Letters A 28, 1350172 (2013) | 10.1142/S0217732313501721 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider Little Rip (LR) and Pseudo Rip (PR) cosmological models with two
interacting ideal fluids, corresponding to dark energy and dark matter. The
interaction between the dark energy and the dark matter fluid components is
described in terms of the parameters in the equations of state for the LR and
PR universes. In contrast to a model containing only a pure dark energy, the
presence of the interaction term between the fluid components in the
gravitational equations leads to a modification of the equation of state
parameters. The properties of the early universe in this formalism are pointed
out.
| [
{
"created": "Thu, 21 Nov 2013 13:29:44 GMT",
"version": "v1"
}
] | 2014-01-28 | [
[
"Brevik",
"I.",
""
],
[
"Timoshkin",
"A. V.",
""
],
[
"Rabochaya",
"Y.",
""
]
] | We consider Little Rip (LR) and Pseudo Rip (PR) cosmological models with two interacting ideal fluids, corresponding to dark energy and dark matter. The interaction between the dark energy and the dark matter fluid components is described in terms of the parameters in the equations of state for the LR and PR universes. In contrast to a model containing only a pure dark energy, the presence of the interaction term between the fluid components in the gravitational equations leads to a modification of the equation of state parameters. The properties of the early universe in this formalism are pointed out. |
gr-qc/9405013 | Genadi A. Sardanashvily | G. Sardanashvily | Gravity as a Higgs Field. I.the Geometric Equivalence Principle | 20 pages, LaTeX file | null | null | null | gr-qc | null | {\it If gravity is a metric field by Einstein, it is a Higgs field.}
Gravitation theory meets spontaneous symmetry breaking in accordance with the
Equivalence Principle reformulated in the spirit of Klein-Chern geometries of
invariants. In gravitation theory, the structure group of the principal linear
frame bundle $LX$ over a world manifold $X^4$ is reducible to the connected
Lorentz group $SO(3,1)$. The physical underlying reason of this reduction is
Dirac fermion matter possessing only exact Lorentz symmetries. The associated
Higgs field is a tetrad gravitational field $h$ represented by a global section
of the quotient $\Si$ of $LX$ by $SO(3,1)$. The feature of gravity as a Higgs
field issues from the fact that, in the presence of different tetrad fields,
Dirac fermion fields are described by spinor bundles associated with different
reduced Lorentz subbundles of $LX$, and we have nonequivalent representations
of cotangent vectors to $X^4$ by Dirac's matrices. It follows that a fermion
field must be regarded only in a pair with a certain tetrad field. These pairs
fail to be represented by sections of any product bundle $S\times\Si$, but
sections of the composite spinor bundle $S\to\Si\to X^4$. They constitute the
so-called fermion-gravitation complex where values of tetrad gravitational
fields play the role of coordinate parameters, besides the familiar world
coordinates. In Part 1 of the article, geometry of the fermion-gravitation
complex is investigated. The goal is the total Dirac operator into which
components of a connection on $S\to\Si$ along tetrad coordinate directions make
contribution. The Part II will be devoted to dynamics of fermion-gravitation
complex. It is a constraint system to describe which we use the covariant
multisymplectic generalization of the Hamiltonian formalism when canonical
momenta correspond to derivatives of fields with respect to all world
coordinates, not only the time.
| [
{
"created": "Fri, 6 May 1994 14:26:38 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Sardanashvily",
"G.",
""
]
] | {\it If gravity is a metric field by Einstein, it is a Higgs field.} Gravitation theory meets spontaneous symmetry breaking in accordance with the Equivalence Principle reformulated in the spirit of Klein-Chern geometries of invariants. In gravitation theory, the structure group of the principal linear frame bundle $LX$ over a world manifold $X^4$ is reducible to the connected Lorentz group $SO(3,1)$. The physical underlying reason of this reduction is Dirac fermion matter possessing only exact Lorentz symmetries. The associated Higgs field is a tetrad gravitational field $h$ represented by a global section of the quotient $\Si$ of $LX$ by $SO(3,1)$. The feature of gravity as a Higgs field issues from the fact that, in the presence of different tetrad fields, Dirac fermion fields are described by spinor bundles associated with different reduced Lorentz subbundles of $LX$, and we have nonequivalent representations of cotangent vectors to $X^4$ by Dirac's matrices. It follows that a fermion field must be regarded only in a pair with a certain tetrad field. These pairs fail to be represented by sections of any product bundle $S\times\Si$, but sections of the composite spinor bundle $S\to\Si\to X^4$. They constitute the so-called fermion-gravitation complex where values of tetrad gravitational fields play the role of coordinate parameters, besides the familiar world coordinates. In Part 1 of the article, geometry of the fermion-gravitation complex is investigated. The goal is the total Dirac operator into which components of a connection on $S\to\Si$ along tetrad coordinate directions make contribution. The Part II will be devoted to dynamics of fermion-gravitation complex. It is a constraint system to describe which we use the covariant multisymplectic generalization of the Hamiltonian formalism when canonical momenta correspond to derivatives of fields with respect to all world coordinates, not only the time. |
1304.3954 | Hernando Quevedo | Hernando Quevedo, Alberto Sanchez and Safia Taj | On the ensemble dependence in black hole geometrothermodynamics | 14 pages, no figures | null | 10.1088/0031-8949/89/8/084007 | CBPF-011 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the dependence of thermodynamic properties of black holes on
the choice of statistical ensemble for a particular class of
Einstein-Maxwell-Gauss-Bonnet black holes with cosmological constant. We use
partial Legendre transformations in the thermodynamic limit in order to compare
the results in different ensembles, and show that the phase transition
structure depend on the choice of thermodynamic potential. This result implies
that thermodynamic metrics which are partially Legendre invariant cannot be
employed to describe black hole thermodynamics, and partly explains why a
particular thermodynamic metric has been used so far in the framework of black
hole geometrothermodynamics.
| [
{
"created": "Sun, 14 Apr 2013 22:05:42 GMT",
"version": "v1"
}
] | 2015-06-15 | [
[
"Quevedo",
"Hernando",
""
],
[
"Sanchez",
"Alberto",
""
],
[
"Taj",
"Safia",
""
]
] | We investigate the dependence of thermodynamic properties of black holes on the choice of statistical ensemble for a particular class of Einstein-Maxwell-Gauss-Bonnet black holes with cosmological constant. We use partial Legendre transformations in the thermodynamic limit in order to compare the results in different ensembles, and show that the phase transition structure depend on the choice of thermodynamic potential. This result implies that thermodynamic metrics which are partially Legendre invariant cannot be employed to describe black hole thermodynamics, and partly explains why a particular thermodynamic metric has been used so far in the framework of black hole geometrothermodynamics. |
2205.01967 | Yusef Maleki | Yusef Maleki and Alireza Maleki | Complementarity-Entanglement Tradeoff in Quantum Gravity | 9 pages, 5 figures | Phys. Rev. D 105, 086024 (2022) | 10.1103/PhysRevD.105.086024 | null | gr-qc hep-th quant-ph | http://creativecommons.org/licenses/by/4.0/ | Quantization of the gravity remains one of the most important, yet extremely
illusive, challenges at the heart of modern physics. Any attempt to resolve
this long-standing problem seems to be doomed, as the route to any direct
empirical evidence (i.e., detecting gravitons) for shedding light on the
quantum aspect of the gravity is far beyond the current capabilities. Recently,
it has been discovered that gravitationally-induced entanglement, tailored in
the interferometric frameworks, can be used to witness the quantum nature of
the gravity. Even though these schemes offer promising tools for investigating
quantum gravity, many fundamental and empirical aspects of the schemes are yet
to be discovered. Considering the fact that, beside quantum entanglement,
quantum uncertainty and complementarity principles are the two other
foundational aspects of quantum physics, the quantum nature of the gravity
needs to manifest all of these features. Here, we lay out an interferometric
platform for testing these three nonclassical aspects of quantum mechanics in
quantum gravity setting, which connects gravity and quantum physics in a
broader and deeper context. As we show in this work, all of these three
fundamental features of quantum gravity can be framed and fully analyzed in an
interferometric scheme.
| [
{
"created": "Wed, 4 May 2022 09:34:10 GMT",
"version": "v1"
}
] | 2022-05-05 | [
[
"Maleki",
"Yusef",
""
],
[
"Maleki",
"Alireza",
""
]
] | Quantization of the gravity remains one of the most important, yet extremely illusive, challenges at the heart of modern physics. Any attempt to resolve this long-standing problem seems to be doomed, as the route to any direct empirical evidence (i.e., detecting gravitons) for shedding light on the quantum aspect of the gravity is far beyond the current capabilities. Recently, it has been discovered that gravitationally-induced entanglement, tailored in the interferometric frameworks, can be used to witness the quantum nature of the gravity. Even though these schemes offer promising tools for investigating quantum gravity, many fundamental and empirical aspects of the schemes are yet to be discovered. Considering the fact that, beside quantum entanglement, quantum uncertainty and complementarity principles are the two other foundational aspects of quantum physics, the quantum nature of the gravity needs to manifest all of these features. Here, we lay out an interferometric platform for testing these three nonclassical aspects of quantum mechanics in quantum gravity setting, which connects gravity and quantum physics in a broader and deeper context. As we show in this work, all of these three fundamental features of quantum gravity can be framed and fully analyzed in an interferometric scheme. |
1002.4880 | Craig J. Hogan | Craig J. Hogan | Interferometers as Probes of Planckian Quantum Geometry | 23 pages, 6 figures, Latex. To appear in Physical Review D | null | 10.1103/PhysRevD.85.064007 | FERMILAB-PUB-10-036-A-T | gr-qc astro-ph.CO hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A theory of position of massive bodies is proposed that results in an
observable quantum behavior of geometry at the Planck scale, $t_P$. Departures
from classical world lines in flat spacetime are described by Planckian
noncommuting operators for position in different directions, as defined by
interactions with null waves. The resulting evolution of position wavefunctions
in two dimensions displays a new kind of directionally-coherent quantum noise
of transverse position. The amplitude of the effect in physical units is
predicted with no parameters, by equating the number of degrees of freedom of
position wavefunctions on a 2D spacelike surface with the entropy density of a
black hole event horizon of the same area. In a region of size $L$, the effect
resembles spatially and directionally coherent random transverse shear
deformations on timescale $\approx L/c$ with typical amplitude $\approx
\sqrt{ct_PL}$. This quantum-geometrical "holographic noise" in position is not
describable as fluctuations of a quantized metric, or as any kind of
fluctuation, dispersion or propagation effect in quantum fields. In a Michelson
interferometer the effect appears as noise that resembles a random Planckian
walk of the beamsplitter for durations up to the light crossing time. Signal
spectra and correlation functions in interferometers are derived, and predicted
to be comparable with the sensitivities of current and planned experiments. It
is proposed that nearly co-located Michelson interferometers of laboratory
scale, cross-correlated at high frequency, can test the Planckian noise
prediction with current technology.
| [
{
"created": "Thu, 25 Feb 2010 21:07:32 GMT",
"version": "v1"
},
{
"created": "Sun, 31 Oct 2010 16:04:38 GMT",
"version": "v10"
},
{
"created": "Mon, 13 Dec 2010 11:57:48 GMT",
"version": "v11"
},
{
"created": "Tue, 4 Jan 2011 23:38:22 GMT",
"version": "v12"
},
{
"created": "Mon, 17 Jan 2011 16:47:14 GMT",
"version": "v13"
},
{
"created": "Fri, 25 Feb 2011 20:20:46 GMT",
"version": "v14"
},
{
"created": "Thu, 3 Mar 2011 00:25:08 GMT",
"version": "v15"
},
{
"created": "Sun, 20 Mar 2011 20:55:49 GMT",
"version": "v16"
},
{
"created": "Sat, 16 Apr 2011 00:50:47 GMT",
"version": "v17"
},
{
"created": "Sun, 24 Apr 2011 16:13:45 GMT",
"version": "v18"
},
{
"created": "Fri, 20 May 2011 19:57:39 GMT",
"version": "v19"
},
{
"created": "Wed, 30 Jun 2010 18:25:06 GMT",
"version": "v2"
},
{
"created": "Mon, 4 Jul 2011 14:54:30 GMT",
"version": "v20"
},
{
"created": "Mon, 1 Aug 2011 15:57:49 GMT",
"version": "v21"
},
{
"created": "Fri, 2 Sep 2011 21:01:02 GMT",
"version": "v22"
},
{
"created": "Mon, 28 Nov 2011 04:08:15 GMT",
"version": "v23"
},
{
"created": "Wed, 30 Nov 2011 05:46:17 GMT",
"version": "v24"
},
{
"created": "Sun, 4 Dec 2011 15:27:04 GMT",
"version": "v25"
},
{
"created": "Mon, 19 Dec 2011 22:56:40 GMT",
"version": "v26"
},
{
"created": "Tue, 7 Feb 2012 15:27:37 GMT",
"version": "v27"
},
{
"created": "Fri, 23 Jul 2010 14:28:58 GMT",
"version": "v3"
},
{
"created": "Tue, 17 Aug 2010 21:33:42 GMT",
"version": "v4"
},
{
"created": "Sun, 22 Aug 2010 06:44:15 GMT",
"version": "v5"
},
{
"created": "Tue, 24 Aug 2010 14:05:12 GMT",
"version": "v6"
},
{
"created": "Thu, 26 Aug 2010 19:09:40 GMT",
"version": "v7"
},
{
"created": "Tue, 12 Oct 2010 22:07:26 GMT",
"version": "v8"
},
{
"created": "Mon, 18 Oct 2010 02:29:45 GMT",
"version": "v9"
}
] | 2013-05-30 | [
[
"Hogan",
"Craig J.",
""
]
] | A theory of position of massive bodies is proposed that results in an observable quantum behavior of geometry at the Planck scale, $t_P$. Departures from classical world lines in flat spacetime are described by Planckian noncommuting operators for position in different directions, as defined by interactions with null waves. The resulting evolution of position wavefunctions in two dimensions displays a new kind of directionally-coherent quantum noise of transverse position. The amplitude of the effect in physical units is predicted with no parameters, by equating the number of degrees of freedom of position wavefunctions on a 2D spacelike surface with the entropy density of a black hole event horizon of the same area. In a region of size $L$, the effect resembles spatially and directionally coherent random transverse shear deformations on timescale $\approx L/c$ with typical amplitude $\approx \sqrt{ct_PL}$. This quantum-geometrical "holographic noise" in position is not describable as fluctuations of a quantized metric, or as any kind of fluctuation, dispersion or propagation effect in quantum fields. In a Michelson interferometer the effect appears as noise that resembles a random Planckian walk of the beamsplitter for durations up to the light crossing time. Signal spectra and correlation functions in interferometers are derived, and predicted to be comparable with the sensitivities of current and planned experiments. It is proposed that nearly co-located Michelson interferometers of laboratory scale, cross-correlated at high frequency, can test the Planckian noise prediction with current technology. |
gr-qc/9409036 | Donald Marolf | Donald Marolf | The Spectral Analysis Inner Product for Quantum Gravity | 5 pages LaTex, UCSBTH-94-38, CGPG-94/9-1 | null | null | null | gr-qc | null | This submission to the Proceedings of the Seventh Marcel-Grossman Conference
is an advertisement for the use of the ``spectral analysis inner product" for
minisuperspace models in quantum gravity.
| [
{
"created": "Fri, 16 Sep 1994 18:36:26 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Marolf",
"Donald",
""
]
] | This submission to the Proceedings of the Seventh Marcel-Grossman Conference is an advertisement for the use of the ``spectral analysis inner product" for minisuperspace models in quantum gravity. |
gr-qc/9801059 | Shahar Hod | Shahar Hod and Tsvi Piran | Late-Time Tails in Gravitational Collapse of a Self-Interacting
(Massive) Scalar-Field and Decay of a Self-Interacting Scalar Hair | 16 pages, 3 ps figures, Revtex | Phys.Rev. D58 (1998) 044018 | 10.1103/PhysRevD.58.044018 | null | gr-qc | null | We study analytically the initial value problem for a self-interacting
(massive) scalar-field on a Reissner-Nordstr\"om spacetime. Following the
no-hair theorem we examine the dynamical physical mechanism by which the
self-interacting (SI) hair decays. We show that the intermediate asymptotic
behaviour of SI perturbations is dominated by an oscillatory inverse power-law
decaying tail. We show that at late-times the decay of a SI hair is slower than
any power-law. We confirm our analytical results by numerical simulations.
| [
{
"created": "Sun, 18 Jan 1998 15:17:01 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Jan 1998 13:32:24 GMT",
"version": "v2"
},
{
"created": "Tue, 6 Oct 1998 09:26:48 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Hod",
"Shahar",
""
],
[
"Piran",
"Tsvi",
""
]
] | We study analytically the initial value problem for a self-interacting (massive) scalar-field on a Reissner-Nordstr\"om spacetime. Following the no-hair theorem we examine the dynamical physical mechanism by which the self-interacting (SI) hair decays. We show that the intermediate asymptotic behaviour of SI perturbations is dominated by an oscillatory inverse power-law decaying tail. We show that at late-times the decay of a SI hair is slower than any power-law. We confirm our analytical results by numerical simulations. |
gr-qc/0005105 | Jljing | Jiliang Jing, Mu-Lin Yan | Statistical Entropy of a Stationary Dilaton Black Hole from Cardy
Formula | 11 pages, no figure, RevTex. Accepted for publication in Phys. Rev. D | Phys.Rev.D63:024003,2001 | 10.1103/PhysRevD.63.024003 | null | gr-qc hep-th | null | With Carlip's boundary conditions, a standard Virasoro subalgebra with
corresponding central charge for stationary dilaton black hole obtained in the
low-energy effective field theory describing string is constructed at a Killing
horizon. The statistical entropy of stationary dilaton black hole yielded by
standard Cardy formula agree with its Bekenstein-Hawking entropy only if we
take period $ T$ of function $v$ as the periodicity of the Euclidean black
hole. On the other hand, if we consider first-order quantum correction then the
entropy contains a logarithmic term with a factor $-{1/2}$, which is different
from Kaul and Majumdar's one, $-{3/2}$. We also show that the discrepancy is
not just for the dilaton black hole, but for any one whose corresponding
central change takes the form $\frac{c}{12}= \frac{A_H}{8\pi
G}\frac{2\pi}{\kappa T}$.
| [
{
"created": "Wed, 24 May 2000 09:03:29 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Sep 2000 14:00:24 GMT",
"version": "v2"
}
] | 2016-08-31 | [
[
"Jing",
"Jiliang",
""
],
[
"Yan",
"Mu-Lin",
""
]
] | With Carlip's boundary conditions, a standard Virasoro subalgebra with corresponding central charge for stationary dilaton black hole obtained in the low-energy effective field theory describing string is constructed at a Killing horizon. The statistical entropy of stationary dilaton black hole yielded by standard Cardy formula agree with its Bekenstein-Hawking entropy only if we take period $ T$ of function $v$ as the periodicity of the Euclidean black hole. On the other hand, if we consider first-order quantum correction then the entropy contains a logarithmic term with a factor $-{1/2}$, which is different from Kaul and Majumdar's one, $-{3/2}$. We also show that the discrepancy is not just for the dilaton black hole, but for any one whose corresponding central change takes the form $\frac{c}{12}= \frac{A_H}{8\pi G}\frac{2\pi}{\kappa T}$. |
2307.00922 | Carlos Bouthelier-Madre | J. L. Alonso, C. Bouthelier-Madre, J. Clemente-Gallardo, D.
Mart\'inez-Crespo | Hybrid Geometrodynamics: A Hamiltonian description of classical gravity
coupled to quantum matter | null | null | 10.1088/1361-6382/ad3459 | null | gr-qc math-ph math.MP quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We generalize the Hamiltonian picture of General Relativity coupled to
classical matter, known as geometrodynamics, to the case where such matter is
described by a Quantum Field Theory in Curved Spacetime, but gravity is still
described by a classical metric tensor field over a spatial hypersurface and
its associated momentum. Thus, in our approach there is no non-dynamic
background structure, apart from the manifold of events, and the gravitational
and quantum degrees of freedom have their dynamics inextricably coupled. Given
the Hamiltonian natureof the framework, we work with the generators of
hypersurface deformations over the manifold of quantum states. The construction
relies heavily on the differential geometry of a fibration of the set of
quantum states over the set of gravitational variables. An important feature of
this work is the use of Gaussian measures over the space of matter fields and
of Hida distributions to define a common superspace to all possible Hilbert
spaces with different measures, to properly characterize the Schrodinger wave
functional picture of QFT in curved spacetime. This allows us to relate states
within different Hilbert spaces in the case of vacuum states or measures that
depend on the gravitational degrees of freedom, as the ones associated to
Ashtekar's complex structure. This is achieved through the inclusion of a
quantum Hermitian connection for the fibration, which will have profound
physical implications. The most remarkable physical features of the
construction are norm conservation of the quantum state (even if the total
dynamics are non-unitary), the clear identification of the hybrid conserved
quantities and the description of a dynamical backreaction of quantum matter on
geometry and vice versa, which shall modify the physical properties the
gravitational field would have in the absence of backreaction.
| [
{
"created": "Mon, 3 Jul 2023 10:46:40 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Feb 2024 22:39:55 GMT",
"version": "v2"
}
] | 2024-03-20 | [
[
"Alonso",
"J. L.",
""
],
[
"Bouthelier-Madre",
"C.",
""
],
[
"Clemente-Gallardo",
"J.",
""
],
[
"Martínez-Crespo",
"D.",
""
]
] | We generalize the Hamiltonian picture of General Relativity coupled to classical matter, known as geometrodynamics, to the case where such matter is described by a Quantum Field Theory in Curved Spacetime, but gravity is still described by a classical metric tensor field over a spatial hypersurface and its associated momentum. Thus, in our approach there is no non-dynamic background structure, apart from the manifold of events, and the gravitational and quantum degrees of freedom have their dynamics inextricably coupled. Given the Hamiltonian natureof the framework, we work with the generators of hypersurface deformations over the manifold of quantum states. The construction relies heavily on the differential geometry of a fibration of the set of quantum states over the set of gravitational variables. An important feature of this work is the use of Gaussian measures over the space of matter fields and of Hida distributions to define a common superspace to all possible Hilbert spaces with different measures, to properly characterize the Schrodinger wave functional picture of QFT in curved spacetime. This allows us to relate states within different Hilbert spaces in the case of vacuum states or measures that depend on the gravitational degrees of freedom, as the ones associated to Ashtekar's complex structure. This is achieved through the inclusion of a quantum Hermitian connection for the fibration, which will have profound physical implications. The most remarkable physical features of the construction are norm conservation of the quantum state (even if the total dynamics are non-unitary), the clear identification of the hybrid conserved quantities and the description of a dynamical backreaction of quantum matter on geometry and vice versa, which shall modify the physical properties the gravitational field would have in the absence of backreaction. |
gr-qc/0210041 | Edward Malec | J. Karkowski, K. Roszkowski, Z. Swierczynski and E. Malec | Waves in Schwarzschild spacetimes: How strong can imprints of the
spacetime curvature be | null | Phys.Rev.D67:064024,2003 | 10.1103/PhysRevD.67.064024 | null | gr-qc | null | Misprints corrected, two references added. To appear in the Phys. Rev. D.
| [
{
"created": "Mon, 14 Oct 2002 12:23:41 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Mar 2003 12:26:46 GMT",
"version": "v2"
}
] | 2014-11-17 | [
[
"Karkowski",
"J.",
""
],
[
"Roszkowski",
"K.",
""
],
[
"Swierczynski",
"Z.",
""
],
[
"Malec",
"E.",
""
]
] | Misprints corrected, two references added. To appear in the Phys. Rev. D. |
gr-qc/0010075 | Pascual-Sanchez J.-F. | J.-F. Pascual-S\'anchez | The harmonic gauge condition in the gravitomagnetic equations | 8 pages, LaTeX, to appear in Il Nuovo Cimento B (2000) | Nuovo Cim. B115 (2000) 725-732 | null | null | gr-qc | null | It has been asserted in the literature that the analogy between the linear
and first order slow motion approximation of Einstein equations of General
Relativity (gravitomagnetic equations) and the Maxwell-Lorentz equations of
electrodynamics breaks down if the gravitational potentials are time dependent.
In this work, we show that this assertion is not correct and it has arisen
from an incorrect limit of the usual harmonic gauge condition, which
drastically changes the physical content of the gravitomagnetic equations.
| [
{
"created": "Fri, 20 Oct 2000 17:31:54 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Pascual-Sánchez",
"J. -F.",
""
]
] | It has been asserted in the literature that the analogy between the linear and first order slow motion approximation of Einstein equations of General Relativity (gravitomagnetic equations) and the Maxwell-Lorentz equations of electrodynamics breaks down if the gravitational potentials are time dependent. In this work, we show that this assertion is not correct and it has arisen from an incorrect limit of the usual harmonic gauge condition, which drastically changes the physical content of the gravitomagnetic equations. |
gr-qc/0202088 | L. Fern\'andez | L. Fernandez-Jambrina (Universidad Politecnica de Madrid, Spain) | Comment on ``Singularity-free Cosmological Solutions with Non-rotating
Perfect Fluids'' | 4 pages, 0 figures, RevTeX4, submitted to Physical Review D | null | null | null | gr-qc | null | A theorem stated by Raychaudhuri which claims that the only physical
non-singular cosmological models are comprised in the Ruiz-Senovilla family is
shown to be incorrect. An explicit counterexample is provided and the failure
of the argument leading to the theorem is explicitly pointed out.
| [
{
"created": "Sun, 24 Feb 2002 21:52:05 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Fernandez-Jambrina",
"L.",
"",
"Universidad Politecnica de Madrid, Spain"
]
] | A theorem stated by Raychaudhuri which claims that the only physical non-singular cosmological models are comprised in the Ruiz-Senovilla family is shown to be incorrect. An explicit counterexample is provided and the failure of the argument leading to the theorem is explicitly pointed out. |
0908.4110 | Kristin Schleich | Kristin Schleich and Donald M. Witt | A simple proof of Birkhoff's theorem for cosmological constant | 10 pages, 5 figures References added; typo in eqn. 12 fixed | null | 10.1063/1.3503447 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a simple, unified proof of Birkhoff's theorem for the vacuum and
cosmological constant case, emphasizing its local nature. We discuss its
implications for the maximal analytic extensions of Schwarzschild,
Schwarzschild(-anti)-de Sitter and Nariai spacetimes. In particular, we note
that the maximal analytic extensions of extremal and over-extremal
Schwarzschild-de Sitter spacetimes exhibit no static region. Hence the common
belief that Birkhoff's theorem implies staticity is false for the case of
positive cosmological constant. Instead, the correct point of view is that
generalized Birkhoff's theorems are local uniqueness theorems whose corollary
is that locally spherically symmetric solutions of Einstein's equations exhibit
an additional local killing vector field.
| [
{
"created": "Thu, 27 Aug 2009 23:35:43 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Oct 2009 17:51:07 GMT",
"version": "v2"
}
] | 2015-05-14 | [
[
"Schleich",
"Kristin",
""
],
[
"Witt",
"Donald M.",
""
]
] | We provide a simple, unified proof of Birkhoff's theorem for the vacuum and cosmological constant case, emphasizing its local nature. We discuss its implications for the maximal analytic extensions of Schwarzschild, Schwarzschild(-anti)-de Sitter and Nariai spacetimes. In particular, we note that the maximal analytic extensions of extremal and over-extremal Schwarzschild-de Sitter spacetimes exhibit no static region. Hence the common belief that Birkhoff's theorem implies staticity is false for the case of positive cosmological constant. Instead, the correct point of view is that generalized Birkhoff's theorems are local uniqueness theorems whose corollary is that locally spherically symmetric solutions of Einstein's equations exhibit an additional local killing vector field. |
2306.10434 | Claudio Cremaschini | Claudio Cremaschini and Zden\v{e}k Stuchl\'ik | Carter-constant induced mechanism for generation of anisotropic kinetic
equilibria in collisionless N-body systems | 14 pages | International Journal of Modern Physics D 26, 1750001 (2017) | 10.1142/S0218271817500018 | null | gr-qc astro-ph.HE cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new intrinsically-relativistic kinetic mechanism for generation of
non-isotropic relativistic kinetic equilibria in collisionless N-body systems
is pointed out. The theory is developed in the framework of the covariant
Vlasov statistical description. The new effect is based on the constraints
placed by the conservation laws of neutral single-particle dynamics in
prescribed background curved-spacetimes demonstrating existence of Killing
tensors. As an illustration, the particular case of the Kerr space-time
admitting the so-called Carter constant for the particle geodesic motion is
considered. The general functional form of the equilibrium kinetic distribution
function (KDF) is determined and an explicit realization in terms of
Gaussian-like distributions is provided. It is shown that, due to the Carter
constant, these equilibrium KDFs exhibit an anisotropic phase-space functional
dependence in terms of the single-particle 4-velocity components, giving rise
to corresponding non-isotropic continuum fluid fields. The qualitative
properties of the equilibrium stress-energy tensor associated with these
systems are discussed, with a particular emphasis on the related occurrence of
temperature anisotropy effects. The theory is susceptible of astrophysical
applications, including in particular the statistical properties of dark matter
halos around stellar-mass or galactic-center black holes.
| [
{
"created": "Sat, 17 Jun 2023 22:50:48 GMT",
"version": "v1"
}
] | 2023-06-21 | [
[
"Cremaschini",
"Claudio",
""
],
[
"Stuchlík",
"Zdeněk",
""
]
] | A new intrinsically-relativistic kinetic mechanism for generation of non-isotropic relativistic kinetic equilibria in collisionless N-body systems is pointed out. The theory is developed in the framework of the covariant Vlasov statistical description. The new effect is based on the constraints placed by the conservation laws of neutral single-particle dynamics in prescribed background curved-spacetimes demonstrating existence of Killing tensors. As an illustration, the particular case of the Kerr space-time admitting the so-called Carter constant for the particle geodesic motion is considered. The general functional form of the equilibrium kinetic distribution function (KDF) is determined and an explicit realization in terms of Gaussian-like distributions is provided. It is shown that, due to the Carter constant, these equilibrium KDFs exhibit an anisotropic phase-space functional dependence in terms of the single-particle 4-velocity components, giving rise to corresponding non-isotropic continuum fluid fields. The qualitative properties of the equilibrium stress-energy tensor associated with these systems are discussed, with a particular emphasis on the related occurrence of temperature anisotropy effects. The theory is susceptible of astrophysical applications, including in particular the statistical properties of dark matter halos around stellar-mass or galactic-center black holes. |
gr-qc/9801018 | Lior M. Burko | Lior M. Burko | Interaction of electromagnetic perturbations with infalling observers
inside spherical charged black holes | null | null | null | TECHNION-PH-95-14 | gr-qc quant-ph | null | The electromagnetic radiation that falls into a Reissner-Nordstr\"{o}m black
hole is known to develop a ``blue sheet'', namely, an infinite concentration of
energy density at the Cauchy horizon. The interaction of these divergent
electromagnetic fields with infalling matter was recently analyzed (L. M. burko
and A. Ori, Phys. Rev. Lett. 74, 1064 (1995)). Here, we give a more detailed
description of that analysis: We consider classical electromagnetic fields
(that were produced during the collapse and then backscattered into the black
hole), and investigate the blue-sheet effects of these fields on infalling
objects within two simplified models of a classical and a quantum absorber.
These effects are found to be finite and even negligible for typical parameters
of a supermassive black hole.
| [
{
"created": "Thu, 8 Jan 1998 14:55:53 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Burko",
"Lior M.",
""
]
] | The electromagnetic radiation that falls into a Reissner-Nordstr\"{o}m black hole is known to develop a ``blue sheet'', namely, an infinite concentration of energy density at the Cauchy horizon. The interaction of these divergent electromagnetic fields with infalling matter was recently analyzed (L. M. burko and A. Ori, Phys. Rev. Lett. 74, 1064 (1995)). Here, we give a more detailed description of that analysis: We consider classical electromagnetic fields (that were produced during the collapse and then backscattered into the black hole), and investigate the blue-sheet effects of these fields on infalling objects within two simplified models of a classical and a quantum absorber. These effects are found to be finite and even negligible for typical parameters of a supermassive black hole. |
gr-qc/0604080 | James S. Graber | James S. Graber | Performing a theoretically robust Ryan test using intermediate-mass
black holes | Poster paper presented at GWDAW-10 10th Gravitational Wave Data
Analysis Workshop. Submitted to Classical & Quantum Gravity; 10 pages LaTeX,
Figure Size Increased | null | null | null | gr-qc | null | We investigate the possibility of using binary IMBH inspirals to perform the
Ryan test of general relativity in a theoretically robust manner using data
from early in the detectable part of the inspiral. We find this to be feasible
and compute the masses of the most favourable systems.
| [
{
"created": "Wed, 19 Apr 2006 12:34:53 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Apr 2006 16:43:04 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Graber",
"James S.",
""
]
] | We investigate the possibility of using binary IMBH inspirals to perform the Ryan test of general relativity in a theoretically robust manner using data from early in the detectable part of the inspiral. We find this to be feasible and compute the masses of the most favourable systems. |
1505.05870 | Masahiro Hotta | Masahiro Hotta and Ayumu Sugita | The Fall of Black Hole Firewall: Natural Nonmaximal Entanglement for
Page Curve | 30 pages, 16 figures, some comments and figures are added | null | 10.1093/ptep/ptv170 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The black hole firewall conjecture is based on Page curve hypothesis, which
claims that entanglement between black hole and Hawking radiation is almost
maximum. The hypothesis is inspired by Lubkin-Lloyd-Pagels-Page theorem for
degenerate systems with zero Hamiltonian. Adopting canonical typicality for
nondegenerate systems with nonvanishing Hamiltonians, the entanglement becomes
nonmaximal,and energetic singularities (firewalls) do not emerge for general
systems. For static thermal pure states of black hole and Hawking radiation,
entanglement entropy equals thermal entropy of the smaller system.
| [
{
"created": "Wed, 20 May 2015 20:39:02 GMT",
"version": "v1"
},
{
"created": "Sat, 6 Jun 2015 02:52:28 GMT",
"version": "v2"
},
{
"created": "Wed, 30 Sep 2015 22:49:57 GMT",
"version": "v3"
},
{
"created": "Fri, 2 Oct 2015 00:44:00 GMT",
"version": "v4"
}
] | 2015-12-23 | [
[
"Hotta",
"Masahiro",
""
],
[
"Sugita",
"Ayumu",
""
]
] | The black hole firewall conjecture is based on Page curve hypothesis, which claims that entanglement between black hole and Hawking radiation is almost maximum. The hypothesis is inspired by Lubkin-Lloyd-Pagels-Page theorem for degenerate systems with zero Hamiltonian. Adopting canonical typicality for nondegenerate systems with nonvanishing Hamiltonians, the entanglement becomes nonmaximal,and energetic singularities (firewalls) do not emerge for general systems. For static thermal pure states of black hole and Hawking radiation, entanglement entropy equals thermal entropy of the smaller system. |
2103.16626 | Christian Pfeifer | Christian Pfeifer and Jos\'e Javier Relancio | Deformed relativistic kinematics on curved spacetime -- a geometric
approach | 19 pages, essay written for the Gravity Research Foundation 2021,
extended to a full article, published version | The European Physical Journal C volume 82, Article number: 150
(2022) | 10.1140/epjc/s10052-022-10066-w | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Deformed relativistic kinematics have been considered as a way to capture
residual effects of quantum gravity. It has been shown that they can be
understood geometrically in terms of a curved momentum space on a flat
spacetime. In this article we present a systematic analysis under which
conditions and how deformed relativistic kinematics, encoded in a momentum
space metric on flat spacetime, can be lifted to curved spacetimes in terms of
a self-consistent cotangent bundle geometry, which leads to purely geometric,
geodesic motion of freely falling point particles. We comment how this
construction is connected to, and offers a new perspective on, non-commutative
spacetimes. From geometric consistency conditions we find that momentum space
metrics can be consistently lifted to curved spacetimes if they either lead to
a dispersion relation which is homogeneous in the momenta, or, if they satisfy
a specific symmetry constraint. The latter is relevant for the momentum space
metrics encoding the most studied deformed relativistic kinematics. For these,
the constraint can only be satisfied in a momentum space basis in which the
momentum space metric is invariant under linear local Lorentz transformations.
We discuss how this result can be interpreted and the consequences of relaxing
some conditions and principles of the construction from which we started.
| [
{
"created": "Tue, 30 Mar 2021 19:06:24 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Aug 2021 08:22:27 GMT",
"version": "v2"
},
{
"created": "Thu, 17 Feb 2022 07:35:44 GMT",
"version": "v3"
}
] | 2022-02-18 | [
[
"Pfeifer",
"Christian",
""
],
[
"Relancio",
"José Javier",
""
]
] | Deformed relativistic kinematics have been considered as a way to capture residual effects of quantum gravity. It has been shown that they can be understood geometrically in terms of a curved momentum space on a flat spacetime. In this article we present a systematic analysis under which conditions and how deformed relativistic kinematics, encoded in a momentum space metric on flat spacetime, can be lifted to curved spacetimes in terms of a self-consistent cotangent bundle geometry, which leads to purely geometric, geodesic motion of freely falling point particles. We comment how this construction is connected to, and offers a new perspective on, non-commutative spacetimes. From geometric consistency conditions we find that momentum space metrics can be consistently lifted to curved spacetimes if they either lead to a dispersion relation which is homogeneous in the momenta, or, if they satisfy a specific symmetry constraint. The latter is relevant for the momentum space metrics encoding the most studied deformed relativistic kinematics. For these, the constraint can only be satisfied in a momentum space basis in which the momentum space metric is invariant under linear local Lorentz transformations. We discuss how this result can be interpreted and the consequences of relaxing some conditions and principles of the construction from which we started. |
2001.03613 | Behzad Tajahmad | Behzad Tajahmad | Raychaudhuri-based reconstruction of anisotropic Einstein-Maxwell
equation in 1+3 covariant formalism of $f(R)$-gravity | 19 pages, 8 figures | null | 10.1140/epjc/s10052-020-7986-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, a new strategy to the reconstruction of $f(R)$-gravity models based
on the Raychaudhuri equation has been suggested by Choudhury et al. In this
paper, utilizing this method, the reconstruction of anisotropic
Einstein-Maxwell equation in the $1+3$ covariant formalism of $f(R)$-gravity is
investigated in four modes: $i.$ Reconstruction from a negative constant
deceleration parameter refereeing to an ever-accelerating universe; $ii.$
Reconstruction from a constant jerk parameter $j=1$ which recovers celebrated
$\Lambda \text{CDM}$ mode of evolution; $iii.$ Reconstruction from a variable
jerk parameter $j=Q(t)$; and $iv.$ Reconstruction from a slowly varying jerk
parameter. Furthermore, two suggestions for enhancing the method are proposed.
| [
{
"created": "Fri, 10 Jan 2020 18:52:14 GMT",
"version": "v1"
}
] | 2020-06-24 | [
[
"Tajahmad",
"Behzad",
""
]
] | Recently, a new strategy to the reconstruction of $f(R)$-gravity models based on the Raychaudhuri equation has been suggested by Choudhury et al. In this paper, utilizing this method, the reconstruction of anisotropic Einstein-Maxwell equation in the $1+3$ covariant formalism of $f(R)$-gravity is investigated in four modes: $i.$ Reconstruction from a negative constant deceleration parameter refereeing to an ever-accelerating universe; $ii.$ Reconstruction from a constant jerk parameter $j=1$ which recovers celebrated $\Lambda \text{CDM}$ mode of evolution; $iii.$ Reconstruction from a variable jerk parameter $j=Q(t)$; and $iv.$ Reconstruction from a slowly varying jerk parameter. Furthermore, two suggestions for enhancing the method are proposed. |
2310.20147 | Jonathan Engle | Jonathan Engle and Simone Speziale | Spinfoams: Foundations | 43 pages, 1 figure, Invited Chapter for the Handbook of Quantum
Gravity (Eds. Bambi, Modesto and Shapiro, Springer 2023) | In: Bambi, C., Modesto, L., Shapiro, I. (eds) Handbook of Quantum
Gravity. Springer, Singapore (2023) | 10.1007/978-981-19-3079-9_99-1 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spinfoams provide a framework for the dynamics of loop quantum gravity that
is manifestly covariant under the full four-dimensional diffeomorphism symmetry
group of general relativity. In this way they complete the ideal of
three-dimensional diffeomorphism covariance that consistently motivates loop
quantum gravity at every step. Specifically, spinfoam models aim to provide a
projector onto, and a physical inner product on, the simultaneous kernel of all
of the constraints of loop quantum gravity by means of a discretization of the
gravitational path integral. In the limit of small Planck constant, they are
closely related to the path integral for Regge calculus, while at the same time
retaining all of the tools of a canonical quantum theory of gravity. They may
also be understood as generalizations of well-understood state sum models for
topological quantum field theories. In this chapter, we review all of these
aspects of spinfoams, as well as review in detail the derivation of the
currently most used spinfoam model, the EPRL model, calculational tools for it,
and the various extensions of it in the literature. We additionally summarize
some of the successes and open problems in the field.
| [
{
"created": "Tue, 31 Oct 2023 03:30:23 GMT",
"version": "v1"
}
] | 2023-11-01 | [
[
"Engle",
"Jonathan",
""
],
[
"Speziale",
"Simone",
""
]
] | Spinfoams provide a framework for the dynamics of loop quantum gravity that is manifestly covariant under the full four-dimensional diffeomorphism symmetry group of general relativity. In this way they complete the ideal of three-dimensional diffeomorphism covariance that consistently motivates loop quantum gravity at every step. Specifically, spinfoam models aim to provide a projector onto, and a physical inner product on, the simultaneous kernel of all of the constraints of loop quantum gravity by means of a discretization of the gravitational path integral. In the limit of small Planck constant, they are closely related to the path integral for Regge calculus, while at the same time retaining all of the tools of a canonical quantum theory of gravity. They may also be understood as generalizations of well-understood state sum models for topological quantum field theories. In this chapter, we review all of these aspects of spinfoams, as well as review in detail the derivation of the currently most used spinfoam model, the EPRL model, calculational tools for it, and the various extensions of it in the literature. We additionally summarize some of the successes and open problems in the field. |
2402.19459 | Jonathan Oppenheim | Jonathan Oppenheim and Andrea Russo | Anomalous contribution to galactic rotation curves due to stochastic
spacetime | v2 : a comment added, and more critical discussion extended, v3 :
comparison with tabletop experiments added | null | null | null | gr-qc astro-ph.GA hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a proposed alternative to quantum gravity, in which the spacetime
metric is treated as classical, even while matter fields remain quantum.
Consistency of the theory necessarily requires that the metric evolve
stochastically. Here, we show that this stochastic behaviour leads to a
modification of general relativity at low accelerations. In the low
acceleration regime, the variance in the acceleration produced by the
gravitational field is high in comparison to that produced by the Newtonian
potential, and can act as an entropic force, causing a deviation from
Einstein's theory of general relativity. We show that in this "diffusion
regime", the entropic force acts from a gravitational point of view, as if it
were a contribution to the matter distribution. We compute modifications to the
expectation value of the metric via the path integral formalism, and find an
anomalous contribution which corresponds to a cosmological constant,
anti-correlated with a contribution which has been used to fit galactic
rotation curves without dark matter. We caution that a greater understanding of
this effect is needed before conclusions can be drawn, most likely through
numerical simulations, and provide a template for computing the deviation from
general relativity which serves as an experimental signature of the Brownian
motion of spacetime.
| [
{
"created": "Thu, 29 Feb 2024 18:52:40 GMT",
"version": "v1"
},
{
"created": "Wed, 1 May 2024 17:54:56 GMT",
"version": "v2"
},
{
"created": "Mon, 22 Jul 2024 17:39:00 GMT",
"version": "v3"
}
] | 2024-07-23 | [
[
"Oppenheim",
"Jonathan",
""
],
[
"Russo",
"Andrea",
""
]
] | We consider a proposed alternative to quantum gravity, in which the spacetime metric is treated as classical, even while matter fields remain quantum. Consistency of the theory necessarily requires that the metric evolve stochastically. Here, we show that this stochastic behaviour leads to a modification of general relativity at low accelerations. In the low acceleration regime, the variance in the acceleration produced by the gravitational field is high in comparison to that produced by the Newtonian potential, and can act as an entropic force, causing a deviation from Einstein's theory of general relativity. We show that in this "diffusion regime", the entropic force acts from a gravitational point of view, as if it were a contribution to the matter distribution. We compute modifications to the expectation value of the metric via the path integral formalism, and find an anomalous contribution which corresponds to a cosmological constant, anti-correlated with a contribution which has been used to fit galactic rotation curves without dark matter. We caution that a greater understanding of this effect is needed before conclusions can be drawn, most likely through numerical simulations, and provide a template for computing the deviation from general relativity which serves as an experimental signature of the Brownian motion of spacetime. |
1903.08556 | Sara Saghafi | Sara Saghafi, Koroush Nozari and Milad Hajebrahimi | Thermodynamics of Non-Commutative Scalar-Tensor-Vector Gravity Black
holes | 17 pages, 5 figures | International Journal of Geometric Methods in Modern Physics,2020 | 10.1142/S0219887821500249 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we analyze the thermodynamic stability of Schwarzschild
Modified Gravity (MOG) black holes in a non-commutative framework. We show
that, unlike a commutative MOG black hole, in the coherent state picture of
non-commutativity MOG black holes are thermodynamically stable. At the final
stage of evaporation, a stable remnant with zero temperature and finite entropy
is left in this noncommutative framework. Also, we consider Parikh-Wilczek
tunneling mechanism of massive particles from non-commutative MOG black holes
and demonstrate that information leaks out of non-commutative MOG black holes
in the form of some non-thermal correlations.
| [
{
"created": "Tue, 19 Mar 2019 14:38:16 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Mar 2019 14:29:42 GMT",
"version": "v2"
},
{
"created": "Mon, 25 Mar 2019 19:48:01 GMT",
"version": "v3"
},
{
"created": "Mon, 8 Apr 2019 05:01:05 GMT",
"version": "v4"
},
{
"created": "Thu, 20 Aug 2020 13:52:12 GMT",
"version": "v5"
}
] | 2020-12-02 | [
[
"Saghafi",
"Sara",
""
],
[
"Nozari",
"Koroush",
""
],
[
"Hajebrahimi",
"Milad",
""
]
] | In this paper, we analyze the thermodynamic stability of Schwarzschild Modified Gravity (MOG) black holes in a non-commutative framework. We show that, unlike a commutative MOG black hole, in the coherent state picture of non-commutativity MOG black holes are thermodynamically stable. At the final stage of evaporation, a stable remnant with zero temperature and finite entropy is left in this noncommutative framework. Also, we consider Parikh-Wilczek tunneling mechanism of massive particles from non-commutative MOG black holes and demonstrate that information leaks out of non-commutative MOG black holes in the form of some non-thermal correlations. |
0705.2325 | Orfeu Bertolami | Orfeu Bertolami | A Curvature Principle for the interaction between universes | Essay selected for an honorable mention by the Gravity Research
Foundation, 2007. Plain latex, 8 pages | Gen.Rel.Grav.40:1891-1898,2008 | 10.1007/s10714-008-0608-6 | DF/IST-2.2007 | gr-qc | null | We propose a Curvature Principle to describe the dynamics of interacting
universes in a multi-universe scenario and show, in the context of a simplified
model, how interaction drives the cosmological constant of one of the universes
toward a vanishingly small value. We also conjecture on how the proposed
Curvature Principle suggests a solution for the entropy paradox of a universe
where the cosmological constant vanishes.
| [
{
"created": "Wed, 16 May 2007 10:49:57 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Bertolami",
"Orfeu",
""
]
] | We propose a Curvature Principle to describe the dynamics of interacting universes in a multi-universe scenario and show, in the context of a simplified model, how interaction drives the cosmological constant of one of the universes toward a vanishingly small value. We also conjecture on how the proposed Curvature Principle suggests a solution for the entropy paradox of a universe where the cosmological constant vanishes. |
2307.04325 | Tayyab Naseer | M. Sharif, Tayyab Naseer | Influence of Charge on Anisotropic Class-one Solution in Non-minimally
Coupled Gravity | 37 pages, 11 figures | Phys. Scr. 97(2022)125016 | 10.1088/1402-4896/aca142 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper studies charged star models associated with anisotropic matter
distribution in $f(\mathcal{R},\mathcal{T},\mathcal{Q})$ theory, where
$\mathcal{Q}=\mathcal{R}_{\phi\psi}\mathcal{T}^{\phi\psi}$. For this purpose,
we take a linear model of this gravity as $\mathcal{R}+\zeta\mathcal{Q}$, where
$\zeta$ represents a coupling constant. We consider a self-gravitating
spherical geometry in the presence of electromagnetic field and generate
solution to the modified field equations by using the ``embedding class-one''
condition and $\mathbb{MIT}$ bag model equation of state. The observational
data (masses and radii) of four different stellar models like 4U 1820-30,~SAX J
1808.4-3658,~SMC X-4 and Her X-I is employed to analyze the effects of charge
on their physical properties. Finally, the effect of the coupling constant is
checked on the viability, hydrostatic equilibrium condition and stability of
the resulting solution. We conclude that the considered models show viable and
stable behavior for all the considered values of charge and $\zeta$.
| [
{
"created": "Mon, 10 Jul 2023 03:39:39 GMT",
"version": "v1"
}
] | 2023-07-11 | [
[
"Sharif",
"M.",
""
],
[
"Naseer",
"Tayyab",
""
]
] | This paper studies charged star models associated with anisotropic matter distribution in $f(\mathcal{R},\mathcal{T},\mathcal{Q})$ theory, where $\mathcal{Q}=\mathcal{R}_{\phi\psi}\mathcal{T}^{\phi\psi}$. For this purpose, we take a linear model of this gravity as $\mathcal{R}+\zeta\mathcal{Q}$, where $\zeta$ represents a coupling constant. We consider a self-gravitating spherical geometry in the presence of electromagnetic field and generate solution to the modified field equations by using the ``embedding class-one'' condition and $\mathbb{MIT}$ bag model equation of state. The observational data (masses and radii) of four different stellar models like 4U 1820-30,~SAX J 1808.4-3658,~SMC X-4 and Her X-I is employed to analyze the effects of charge on their physical properties. Finally, the effect of the coupling constant is checked on the viability, hydrostatic equilibrium condition and stability of the resulting solution. We conclude that the considered models show viable and stable behavior for all the considered values of charge and $\zeta$. |
1911.09094 | Jose Socorro Garcia | J. Socorro, S. P\'erez-Pay\'an, Abraham Espinoza-Garc\'ia and Luis Rey
D\'iaz-Barr\'on | Cosmological volume acceleration in dust epoch: using scaling solutions
and variable cosmological term $\Lambda(t)$ within an anisotropic
cosmological model | 12 pages, two figures, Mayor changes in abstract, introduction and
title, and we add 11 references. To publish in Astrophysics Space Science
Journal | null | 10.1007/s10509-020-03810-9 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Under the premise that the current observations of the cosmic microwave
background radiation set a very stringent limit to the anisotropy of the
universe, we consider an anistropic model in the presence of a barotropic
perfect fluid and a homogeneous scalar field, which transits to a flat FRW
cosmology for late times in a dust epoch, presenting an accelerated volume
expansion. Furtheremore, the scalar field is identified with a varying
cosmological term via $V(\phi(t))=2\Lambda(t)$. Exact solutions to the EKG
system are obtained by proposing an anisotropic extension of the scaling
solutions scenario:
$\rm\rho\sim \eta^{-n},\ \rho_\phi\sim \eta^{-m}$, with $\rm\eta^3=a_1a_2a_3$
the volume function of
the anistropic model ($\rm a_1,\, a_2,\, a_3$ being the scale factors).
| [
{
"created": "Wed, 20 Nov 2019 05:18:00 GMT",
"version": "v1"
},
{
"created": "Fri, 29 May 2020 19:15:58 GMT",
"version": "v2"
}
] | 2020-06-02 | [
[
"Socorro",
"J.",
""
],
[
"Pérez-Payán",
"S.",
""
],
[
"Espinoza-García",
"Abraham",
""
],
[
"Díaz-Barrón",
"Luis Rey",
""
]
] | Under the premise that the current observations of the cosmic microwave background radiation set a very stringent limit to the anisotropy of the universe, we consider an anistropic model in the presence of a barotropic perfect fluid and a homogeneous scalar field, which transits to a flat FRW cosmology for late times in a dust epoch, presenting an accelerated volume expansion. Furtheremore, the scalar field is identified with a varying cosmological term via $V(\phi(t))=2\Lambda(t)$. Exact solutions to the EKG system are obtained by proposing an anisotropic extension of the scaling solutions scenario: $\rm\rho\sim \eta^{-n},\ \rho_\phi\sim \eta^{-m}$, with $\rm\eta^3=a_1a_2a_3$ the volume function of the anistropic model ($\rm a_1,\, a_2,\, a_3$ being the scale factors). |
gr-qc/0207019 | Yasusada Nambu | Yasusada Nambu and Shin-ichi Ohokata | Long-wavelength Cosmological Perturbation in the Universe with Multiple
Perfect Fluids | to be published in CQG | Class.Quant.Grav. 19 (2002) 4263-4272 | 10.1088/0264-9381/19/16/303 | null | gr-qc | null | We investigate the large scale cosmological perturbation in the Universe with
multiple perfect fluids. Using the long-wavelength approximation with
Hamilton-Jacobi method, we derive the formula for the gauge invariant comoving
curvature perturbation. As an application of our approach, we examine the large
scale perturbation in a brane cosmology.
| [
{
"created": "Wed, 3 Jul 2002 07:42:10 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Nambu",
"Yasusada",
""
],
[
"Ohokata",
"Shin-ichi",
""
]
] | We investigate the large scale cosmological perturbation in the Universe with multiple perfect fluids. Using the long-wavelength approximation with Hamilton-Jacobi method, we derive the formula for the gauge invariant comoving curvature perturbation. As an application of our approach, we examine the large scale perturbation in a brane cosmology. |
1401.3279 | Sumanta Chakraborty | Sumanta Chakraborty, Soumitra SenGupta | Bulk scalar field in warped extra dimensional models | Mathches published version; 14 pages, two figures | Phys. Rev. D 89, 126001 (2014) | 10.1103/PhysRevD.89.126001 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work presents a general formalism to analyze a generic bulk scalar field
in a multiple warped extra-dimensional model with arbitrary number of extra
dimensions. The Kaluza-Klein mass modes along with the self-interaction
couplings are determined and the possibility of having lowest lying KK mode
masses near TeV scale are discussed. Also some numerical values for low-lying
KK modes has been presented showing explicit localization around TeV scale. It
is argued that the appearance of large number of closely spaced KK modes with
enhanced coupling may prompt possible new signatures in collider physics.
| [
{
"created": "Sat, 11 Jan 2014 10:24:50 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Jun 2014 12:35:44 GMT",
"version": "v2"
}
] | 2014-06-05 | [
[
"Chakraborty",
"Sumanta",
""
],
[
"SenGupta",
"Soumitra",
""
]
] | This work presents a general formalism to analyze a generic bulk scalar field in a multiple warped extra-dimensional model with arbitrary number of extra dimensions. The Kaluza-Klein mass modes along with the self-interaction couplings are determined and the possibility of having lowest lying KK mode masses near TeV scale are discussed. Also some numerical values for low-lying KK modes has been presented showing explicit localization around TeV scale. It is argued that the appearance of large number of closely spaced KK modes with enhanced coupling may prompt possible new signatures in collider physics. |
0912.0476 | Valeriu Predoi | V. Predoi, J. Clark, T. Creighton, E. Daw, S. Fairhurst, I. S. Heng,
J. Kanner, T. Regimbau, P. Shawhan, X. Siemens, P. Sutton, A. Vecchio, D.
White, G. Woan | Prospects for joint radio telescope and gravitational wave searches for
astrophysical transients | 12 pages, Amaldi 8 Conference (New York, 2009) proceedings paper | null | 10.1088/0264-9381/27/8/084018 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The radio skies remain mostly unobserved when it comes to transient
phenomena. The direct detection of gravitational waves will mark a major
milestone of modern astronomy, as an entirely new window will open on the
universe. Two apparently independent phenomena can be brought together in a
coincident effort that has the potential to boost both searches. In this paper
we will outline the scientific case that stands behind these future joint
observations and will describe the methods that might be used to conduct the
searches and analyze the data. The targeted sources are binary systems of
compact objects, known to be strong candidate sources for gravitational waves.
Detection of transients coincident in these two channels would be a significant
smoking gun for first direct detection of gravitational waves, and would open
up a new field for characterization of astrophysical transients involving
massive compact objects.
| [
{
"created": "Wed, 2 Dec 2009 17:47:22 GMT",
"version": "v1"
}
] | 2015-05-14 | [
[
"Predoi",
"V.",
""
],
[
"Clark",
"J.",
""
],
[
"Creighton",
"T.",
""
],
[
"Daw",
"E.",
""
],
[
"Fairhurst",
"S.",
""
],
[
"Heng",
"I. S.",
""
],
[
"Kanner",
"J.",
""
],
[
"Regimbau",
"T.",
""
],
[
"Shawhan",
"P.",
""
],
[
"Siemens",
"X.",
""
],
[
"Sutton",
"P.",
""
],
[
"Vecchio",
"A.",
""
],
[
"White",
"D.",
""
],
[
"Woan",
"G.",
""
]
] | The radio skies remain mostly unobserved when it comes to transient phenomena. The direct detection of gravitational waves will mark a major milestone of modern astronomy, as an entirely new window will open on the universe. Two apparently independent phenomena can be brought together in a coincident effort that has the potential to boost both searches. In this paper we will outline the scientific case that stands behind these future joint observations and will describe the methods that might be used to conduct the searches and analyze the data. The targeted sources are binary systems of compact objects, known to be strong candidate sources for gravitational waves. Detection of transients coincident in these two channels would be a significant smoking gun for first direct detection of gravitational waves, and would open up a new field for characterization of astrophysical transients involving massive compact objects. |
1406.3918 | Hemwati Nandan | Rashmi Uniyal, Hemwati Nandan and K.D. Purohit | Geodesic Motion in a Charged 2D Stringy Blackhole Spacetime | 17 pages, 6 figures | Mod. Phys. Lett. A, Vol. 29, No. 29 (2014) 1450157 | 10.1142/S0217732314501570 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the timelike geodesics and geodesic deviation for a two-dimensional
stringy blackhole spacetime in Schwarzschild gauge. We have analyzed the
properties of effective potential along with the structure of the possible
orbits for test particles with different settings of blackhole parameters. The
exactly solvable geodesic deviation equation is used to obtain corresponding
deviation vector. The nature of deviation and tidal force is also examined in
view of the behavior of corresponding deviation vector.The results are also
compared with an another two-dimensional stringy blackhole spacetime.
| [
{
"created": "Mon, 16 Jun 2014 06:54:00 GMT",
"version": "v1"
}
] | 2014-09-23 | [
[
"Uniyal",
"Rashmi",
""
],
[
"Nandan",
"Hemwati",
""
],
[
"Purohit",
"K. D.",
""
]
] | We study the timelike geodesics and geodesic deviation for a two-dimensional stringy blackhole spacetime in Schwarzschild gauge. We have analyzed the properties of effective potential along with the structure of the possible orbits for test particles with different settings of blackhole parameters. The exactly solvable geodesic deviation equation is used to obtain corresponding deviation vector. The nature of deviation and tidal force is also examined in view of the behavior of corresponding deviation vector.The results are also compared with an another two-dimensional stringy blackhole spacetime. |
1602.00697 | Pierre Christian | Pierre Christian | Newton's Theorem of Revolving Orbits in Curved Spacetime | 10 pages, 7 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Newton's theorem of revolving orbits states that one can multiply the angular
speed of a Keplerian orbit by a factor $k$ by applying a radial inverse cubed
force proportional to $(1-k^2)$. In this paper we derive an extension of this
theorem in general relativity, valid for the motion of massive particles in any
static, spherically symmetric metrics. We verify the Newtonian limit of this
extension and demonstrate that there is no such generalization for rotating
metrics. Further we also extend the theory to the case of charged particles in
the Einstein-Maxwell and Kaluza-Klein theories.
| [
{
"created": "Mon, 1 Feb 2016 21:00:07 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Feb 2016 20:35:23 GMT",
"version": "v2"
},
{
"created": "Tue, 4 Oct 2016 23:37:44 GMT",
"version": "v3"
}
] | 2016-10-06 | [
[
"Christian",
"Pierre",
""
]
] | Newton's theorem of revolving orbits states that one can multiply the angular speed of a Keplerian orbit by a factor $k$ by applying a radial inverse cubed force proportional to $(1-k^2)$. In this paper we derive an extension of this theorem in general relativity, valid for the motion of massive particles in any static, spherically symmetric metrics. We verify the Newtonian limit of this extension and demonstrate that there is no such generalization for rotating metrics. Further we also extend the theory to the case of charged particles in the Einstein-Maxwell and Kaluza-Klein theories. |
0902.0351 | Florian Conrady | Florian Conrady and Laurent Freidel (Perimeter Inst. Theor. Phys.) | Quantum geometry from phase space reduction | 33 pages, 1 figure | J.Math.Phys.50:123510,2009 | 10.1063/1.3257109 | PI-QG-118 | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we give an explicit isomorphism between the usual spin network
basis and the direct quantization of the reduced phase space of tetrahedra. The
main outcome is a formula that describes the space of SU(2) invariant states by
an integral over coherent states satisfying the closure constraint exactly, or
equivalently, as an integral over the space of classical tetrahedra. This
provides an explicit realization of theorems by Guillemin--Sternberg and Hall
that describe the commutation of quantization and reduction. In the final part
of the paper, we use our result to express the FK spin foam model as an
integral over classical tetrahedra and the asymptotics of the vertex amplitude
is determined.
| [
{
"created": "Mon, 2 Feb 2009 20:50:13 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Feb 2009 20:37:00 GMT",
"version": "v2"
},
{
"created": "Thu, 19 Mar 2009 12:20:42 GMT",
"version": "v3"
}
] | 2010-01-15 | [
[
"Conrady",
"Florian",
"",
"Perimeter Inst. Theor. Phys."
],
[
"Freidel",
"Laurent",
"",
"Perimeter Inst. Theor. Phys."
]
] | In this work we give an explicit isomorphism between the usual spin network basis and the direct quantization of the reduced phase space of tetrahedra. The main outcome is a formula that describes the space of SU(2) invariant states by an integral over coherent states satisfying the closure constraint exactly, or equivalently, as an integral over the space of classical tetrahedra. This provides an explicit realization of theorems by Guillemin--Sternberg and Hall that describe the commutation of quantization and reduction. In the final part of the paper, we use our result to express the FK spin foam model as an integral over classical tetrahedra and the asymptotics of the vertex amplitude is determined. |
gr-qc/9312029 | Jorge Pullin | C. Di Bartolo, R. Gambini, J. Griego and J. Pullin | Extended Loops: A New Arena for Nonperturbative Quantum Gravity | 12pp, Revtex, no figures, CGPG-93/12-1 | Phys.Rev.Lett. 72 (1994) 3638-3641 | 10.1103/PhysRevLett.72.3638 | null | gr-qc hep-th | null | We propose a new representation for gauge theories and quantum gravity. It
can be viewed as a generalization of the loop representation. We make use of a
recently introduced extension of the group of loops into a Lie Group. This
extension allows the use of functional methods to solve the constraint
equations. It puts in a precise framework the regularization problems of the
loop representation. It has practical advantages in the search for quantum
states. We present new solutions to the Wheeler-DeWitt equation that reinforce
the conjecture that the Jones Polynomial is a state of nonperturbative quantum
gravity.
| [
{
"created": "Fri, 17 Dec 1993 16:06:53 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Di Bartolo",
"C.",
""
],
[
"Gambini",
"R.",
""
],
[
"Griego",
"J.",
""
],
[
"Pullin",
"J.",
""
]
] | We propose a new representation for gauge theories and quantum gravity. It can be viewed as a generalization of the loop representation. We make use of a recently introduced extension of the group of loops into a Lie Group. This extension allows the use of functional methods to solve the constraint equations. It puts in a precise framework the regularization problems of the loop representation. It has practical advantages in the search for quantum states. We present new solutions to the Wheeler-DeWitt equation that reinforce the conjecture that the Jones Polynomial is a state of nonperturbative quantum gravity. |
2204.10150 | Hajar Belmahi | A. Belhaj, H. Belmahi, M. Benali, H. El Moumni | Light Deflection by Rotating Regular Black Holes with a Cosmological
Constant | latex, 16 pages, 4 figures. Accepted for publication in Chin. J. Phys
2022 | null | 10.1016/j.cjph.2022.04.013 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the Gauss-Bonnet theorem, we compute and examine the deflection angle
of light rays by rotating regular black holes with a cosmological constant. By
the help of optical geometries, we first deal with the Hayward black holes with
cosmological contributions. Then, we reconsider the study of the Bardeen
solutions. We inspect the cosmological constant effect on the deflection angle
of light rays. Concretely, we find extra cosmological correction terms
generalizing certain obtained findings. Using graphical analysis, we provide a
comparative discussion with respect to the Kerr solutions. The results confirm
that the non-linear electrodynamic charges affect the space-time geometry by
decreasing the deflection angle of light rays by such cosmological black holes.
| [
{
"created": "Thu, 21 Apr 2022 14:58:43 GMT",
"version": "v1"
}
] | 2022-11-30 | [
[
"Belhaj",
"A.",
""
],
[
"Belmahi",
"H.",
""
],
[
"Benali",
"M.",
""
],
[
"Moumni",
"H. El",
""
]
] | Using the Gauss-Bonnet theorem, we compute and examine the deflection angle of light rays by rotating regular black holes with a cosmological constant. By the help of optical geometries, we first deal with the Hayward black holes with cosmological contributions. Then, we reconsider the study of the Bardeen solutions. We inspect the cosmological constant effect on the deflection angle of light rays. Concretely, we find extra cosmological correction terms generalizing certain obtained findings. Using graphical analysis, we provide a comparative discussion with respect to the Kerr solutions. The results confirm that the non-linear electrodynamic charges affect the space-time geometry by decreasing the deflection angle of light rays by such cosmological black holes. |
2207.13454 | Clifford M. Will | Fatemeh Taherasghari and Clifford M. Will | Modified geodesic equations of motion for compact bodies in alternative
theories gravity | 8 pages | null | 10.1103/PhysRevD.106.064021 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We derive exact, modified geodesic equations for a system of non-spinning,
self-gravitating interacting bodies in a class of alternative theories of
gravity to general relativity. We use a prescription proposed by Eardley for
incorporating the effects of self-gravity within gravitationally bound bodies,
in which their masses may depend on invariant quantities constructed from the
auxiliary scalar, vector or tensor fields introduced by such theories,
evaluated in the vicinity of each body. The forms of the equations are
independent of the field equations of the chosen theory. In the case where the
masses are strictly constant, the equations reduce to the conventional geodesic
equations of general relativity. These equations may be useful tools for
deriving equations of motion for compact bodies to high post-Newtonian orders
in alternative theories of gravity.
| [
{
"created": "Wed, 27 Jul 2022 11:12:27 GMT",
"version": "v1"
}
] | 2022-10-05 | [
[
"Taherasghari",
"Fatemeh",
""
],
[
"Will",
"Clifford M.",
""
]
] | We derive exact, modified geodesic equations for a system of non-spinning, self-gravitating interacting bodies in a class of alternative theories of gravity to general relativity. We use a prescription proposed by Eardley for incorporating the effects of self-gravity within gravitationally bound bodies, in which their masses may depend on invariant quantities constructed from the auxiliary scalar, vector or tensor fields introduced by such theories, evaluated in the vicinity of each body. The forms of the equations are independent of the field equations of the chosen theory. In the case where the masses are strictly constant, the equations reduce to the conventional geodesic equations of general relativity. These equations may be useful tools for deriving equations of motion for compact bodies to high post-Newtonian orders in alternative theories of gravity. |
1205.2481 | Luca Lusanna | Luca Lusanna | From Clock Synchronization to Dark Matter as a Relativistic Inertial
Effect | 90 pages. Lecture at BOSS2011 | null | 10.1007/978-3-319-00215-6_8 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Lecture at BOSS2011 on relativistic metrology, on clock synchronization,
relativistic dynamics and non-inertial frames in Minkowski spacetime, on
relativistic atomic physics, on ADM canonical tetrad gravity in asymptotically
Minkowskian spacetimes, on the York canonical basis identifying the inertial
(gauge) and tidal degrees of freedom of the gravitational field, on the
Post-Minkowskian linearization in 3-orthogonal gauges, on the Post-Newtonian
limit of matter Hamilton equations, on the possibility to interpret dark matter
as a relativistic inertial effect connected with relativistic metrology (i.e.
clock synchronization) in Einstein GR.
| [
{
"created": "Fri, 11 May 2012 10:56:25 GMT",
"version": "v1"
}
] | 2015-06-05 | [
[
"Lusanna",
"Luca",
""
]
] | Lecture at BOSS2011 on relativistic metrology, on clock synchronization, relativistic dynamics and non-inertial frames in Minkowski spacetime, on relativistic atomic physics, on ADM canonical tetrad gravity in asymptotically Minkowskian spacetimes, on the York canonical basis identifying the inertial (gauge) and tidal degrees of freedom of the gravitational field, on the Post-Minkowskian linearization in 3-orthogonal gauges, on the Post-Newtonian limit of matter Hamilton equations, on the possibility to interpret dark matter as a relativistic inertial effect connected with relativistic metrology (i.e. clock synchronization) in Einstein GR. |
1801.08373 | Rabin Banerjee | Rabin Banerjee and Pradip Mukherjee | On the subtelties of nonrelativistic reduction and applications | 29 pages, no figure | null | 10.1016/j.nuclphysb.2018.11.002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Various subtleties and problems associated with nonrelativistic (NR)
reduction of a scalar field theory to the Schroedinger theory are discussed.
Contrary to the usual approaches that discuss the mapping among the equations
of motion or the actions, we highlight the mapping among the space time
generators. Using a null reduction we show the embedding of the conformal
generators of the Schroedinger theory to that of a complex scalar theory in one
higher dimension. As applications we reveal the conformal symmetry in
hydrodynamics and the obtention of NR diffeomorphism symmetry from the
relativistic one. A geometrical connection based on Horava-Lifshitz and
Newton-Cartan spacetime is discussed.
| [
{
"created": "Thu, 25 Jan 2018 12:20:50 GMT",
"version": "v1"
}
] | 2018-12-05 | [
[
"Banerjee",
"Rabin",
""
],
[
"Mukherjee",
"Pradip",
""
]
] | Various subtleties and problems associated with nonrelativistic (NR) reduction of a scalar field theory to the Schroedinger theory are discussed. Contrary to the usual approaches that discuss the mapping among the equations of motion or the actions, we highlight the mapping among the space time generators. Using a null reduction we show the embedding of the conformal generators of the Schroedinger theory to that of a complex scalar theory in one higher dimension. As applications we reveal the conformal symmetry in hydrodynamics and the obtention of NR diffeomorphism symmetry from the relativistic one. A geometrical connection based on Horava-Lifshitz and Newton-Cartan spacetime is discussed. |
gr-qc/0502095 | Pavel Krtous | Pavel Krtous, Jiri Podolsky | Asymptotic directional structure of radiative fields in spacetimes with
a cosmological constant | CQG Topical Review (44 pages, 6 figures) | Class.Quant.Grav. 21 (2004) R233-R273 | null | null | gr-qc | null | We analyze the directional properties of general gravitational,
electromagnetic, and spin-s fields near conformal infinity I. The fields are
evaluated in normalized tetrads which are parallelly propagated along null
geodesics which approach a point P of I. The standard peeling-off property is
recovered and its meaning is discussed and refined. When the (local) character
of the conformal infinity is null, such as in asymptotically flat spacetimes,
the dominant term which is identified with radiation is unique. However, for
spacetimes with a non-vanishing cosmological constant the conformal infinity is
spacelike (for Lambda>0) or timelike (for Lambda<0), and the radiative
component of each field depends substantially on the null direction along which
P is approached. The directional dependence of asymptotic fields near such de
Sitter-like or anti-de Sitter-like I is explicitly found and described. We
demonstrate that the corresponding directional structure of radiation has a
universal character that is determined by the algebraic (Petrov) type of the
field. In particular, when Lambda>0 the radiation vanishes only along
directions which are opposite to principal null directions. For Lambda<0 the
directional dependence is more complicated because it is necessary to
distinguish outgoing and ingoing radiation. Near such anti-de Sitter-like
conformal infinity the corresponding directional structures differ, depending
not only on the number and degeneracy of the principal null directions at P but
also on their specific orientation with respect to I. The directional structure
of radiation near (anti-)de Sitter-like infinities supplements the standard
peeling-off property of spin-s fields. This offers a better understanding of
the asymptotic behaviour of the fields near conformal infinity.
| [
{
"created": "Tue, 22 Feb 2005 16:06:14 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Krtous",
"Pavel",
""
],
[
"Podolsky",
"Jiri",
""
]
] | We analyze the directional properties of general gravitational, electromagnetic, and spin-s fields near conformal infinity I. The fields are evaluated in normalized tetrads which are parallelly propagated along null geodesics which approach a point P of I. The standard peeling-off property is recovered and its meaning is discussed and refined. When the (local) character of the conformal infinity is null, such as in asymptotically flat spacetimes, the dominant term which is identified with radiation is unique. However, for spacetimes with a non-vanishing cosmological constant the conformal infinity is spacelike (for Lambda>0) or timelike (for Lambda<0), and the radiative component of each field depends substantially on the null direction along which P is approached. The directional dependence of asymptotic fields near such de Sitter-like or anti-de Sitter-like I is explicitly found and described. We demonstrate that the corresponding directional structure of radiation has a universal character that is determined by the algebraic (Petrov) type of the field. In particular, when Lambda>0 the radiation vanishes only along directions which are opposite to principal null directions. For Lambda<0 the directional dependence is more complicated because it is necessary to distinguish outgoing and ingoing radiation. Near such anti-de Sitter-like conformal infinity the corresponding directional structures differ, depending not only on the number and degeneracy of the principal null directions at P but also on their specific orientation with respect to I. The directional structure of radiation near (anti-)de Sitter-like infinities supplements the standard peeling-off property of spin-s fields. This offers a better understanding of the asymptotic behaviour of the fields near conformal infinity. |
1109.5793 | Hanno Sahlmann | Hanno Sahlmann and Thomas Thiemann | Chern-Simons expectation values and quantum horizons from LQG and the
Duflo map | 5 pages, 2 figures. v2: update of bibliography, correction of typos,
virtually identical to published version | Phys. Rev. Lett. 108, 111303 (2012) | 10.1103/PhysRevLett.108.111303 | APCTP Pre2011-007 | gr-qc math-ph math.MP math.QA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We report on a new approach to the calculation of Chern-Simons theory
expectation values, using the mathematical underpinnings of loop quantum
gravity, as well as the Duflo map, a quantization map for functions on Lie
algebras. These new developments can be used in the quantum theory for certain
types of black hole horizons, and they may offer new insights for loop quantum
gravity, Chern-Simons theory and the theory of quantum groups.
| [
{
"created": "Tue, 27 Sep 2011 07:28:34 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Mar 2012 07:21:28 GMT",
"version": "v2"
}
] | 2012-03-28 | [
[
"Sahlmann",
"Hanno",
""
],
[
"Thiemann",
"Thomas",
""
]
] | We report on a new approach to the calculation of Chern-Simons theory expectation values, using the mathematical underpinnings of loop quantum gravity, as well as the Duflo map, a quantization map for functions on Lie algebras. These new developments can be used in the quantum theory for certain types of black hole horizons, and they may offer new insights for loop quantum gravity, Chern-Simons theory and the theory of quantum groups. |
2209.10851 | Quentin Baghi | Quentin Baghi, John G. Baker, Jacob Slutsky, James Ira Thorpe | Fully data-driven time-delay interferometry with time-varying delays | 12 pages, 7 figures. Update Eqs. (1) and (2) to generalize them to
all possible TDI combinations. Other minor changes | Annalen Der Physik 2023, 2200447 | 10.1002/andp.202200447 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Raw space-based gravitational-wave data like LISA's phase measurements are
dominated by laser frequency noise. The standard technique to make this data
usable for science is time-delay interferometry (TDI), which cancels laser
noise terms by forming suitable combinations of delayed measurements. We
recently introduced the basic concepts of an alternative approach which, unlike
TDI, does not rely on independent knowledge of temporal correlations in the
dominant noise. Instead, our automated Principal Component Interferometry
(aPCI) processing only assumes that one can produce some linear combinations of
the temporally nearby regularly spaced phase measurements, which cancel the
laser noise. Then we let the data reveal those combinations. Our previous work
relies on the simplifying additional assumption that the filters which lead to
the laser-noise-free data streams are time-independent. In LISA, however, these
filters will vary as the constellation armlengths evolve. Here, we discuss a
generalization of the basic aPCI concept compatible with data dominated by a
still unmodeled but slowly varying noise covariance. Despite its independence
on any model, aPCI successfully mitigates laser frequency noise below the other
noises' level, and its sensitivity to gravitational waves is the same as the
state-of-the-art second-generation TDI, up to a 2\% error.
| [
{
"created": "Thu, 22 Sep 2022 08:33:58 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Apr 2023 09:11:52 GMT",
"version": "v2"
}
] | 2023-04-12 | [
[
"Baghi",
"Quentin",
""
],
[
"Baker",
"John G.",
""
],
[
"Slutsky",
"Jacob",
""
],
[
"Thorpe",
"James Ira",
""
]
] | Raw space-based gravitational-wave data like LISA's phase measurements are dominated by laser frequency noise. The standard technique to make this data usable for science is time-delay interferometry (TDI), which cancels laser noise terms by forming suitable combinations of delayed measurements. We recently introduced the basic concepts of an alternative approach which, unlike TDI, does not rely on independent knowledge of temporal correlations in the dominant noise. Instead, our automated Principal Component Interferometry (aPCI) processing only assumes that one can produce some linear combinations of the temporally nearby regularly spaced phase measurements, which cancel the laser noise. Then we let the data reveal those combinations. Our previous work relies on the simplifying additional assumption that the filters which lead to the laser-noise-free data streams are time-independent. In LISA, however, these filters will vary as the constellation armlengths evolve. Here, we discuss a generalization of the basic aPCI concept compatible with data dominated by a still unmodeled but slowly varying noise covariance. Despite its independence on any model, aPCI successfully mitigates laser frequency noise below the other noises' level, and its sensitivity to gravitational waves is the same as the state-of-the-art second-generation TDI, up to a 2\% error. |
2207.13654 | Sergey Paston | S.A. Paston, T.I. Zaitseva | Canonical formulation of embedding gravity in a form of General
Relativity with dark matter | LaTeX, 15 pages. This version corresponds to the published one | Gravitation and Cosmology 29 (2023) 153 | 10.1134/S0202289323020093 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study embedding gravity, a modified theory of gravity, in which our
space-time is assumed to be a four-dimensional surface in flat ten-dimensional
space. Based on a simple geometric idea, this theory can be reformulated as
General Relativity with additional degrees of freedom and contribution to
action, which can be interpreted as describing dark matter. We study the
canonical formalism for such a formulation of embedding gravity. After solving
simple constraints, the Hamiltonian is reduced to a linear combination of four
first class constraints with Lagrange multipliers. There still remain six pairs
of second class constraints. Possible ways of taking these constraints into
account are discussed. We show that one way of solving the constraints leads to
the canonical system going into the previously known canonical formulation of
the complete embedding theory with an implicitly defined constraint.
| [
{
"created": "Wed, 27 Jul 2022 17:20:08 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Jul 2023 11:34:26 GMT",
"version": "v2"
}
] | 2023-07-04 | [
[
"Paston",
"S. A.",
""
],
[
"Zaitseva",
"T. I.",
""
]
] | We study embedding gravity, a modified theory of gravity, in which our space-time is assumed to be a four-dimensional surface in flat ten-dimensional space. Based on a simple geometric idea, this theory can be reformulated as General Relativity with additional degrees of freedom and contribution to action, which can be interpreted as describing dark matter. We study the canonical formalism for such a formulation of embedding gravity. After solving simple constraints, the Hamiltonian is reduced to a linear combination of four first class constraints with Lagrange multipliers. There still remain six pairs of second class constraints. Possible ways of taking these constraints into account are discussed. We show that one way of solving the constraints leads to the canonical system going into the previously known canonical formulation of the complete embedding theory with an implicitly defined constraint. |
2211.15534 | Ming Zhang | Chaoxi Fang, Jie Jiang, Ming Zhang | Revisiting thermodynamic topologies of black holes | 18 pages | null | 10.1007/JHEP01(2023)102 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-nd/4.0/ | In the generalized off-shell free energy landscape, black holes can be
treated as thermodynamic topological defects. The local topological properties
of the spacetime can be reflected by the winding numbers at the defects, while
the global topological nature can be classified by the topological number which
is the sum of all local winding numbers. We propose that the winding numbers
can be calculated via the residues of isolated one-order pole points of
characterized functions constructed from the off-shell free energy. Using the
residue method, we show that the topologies of black holes can be divided into
three classes with the topological numbers being -1, 0, and 1, respectively,
being consistent with the results obtained in [Phys. Rev. Lett. 129, 191101
(2022)] by using the topological current method. Moreover, we point out that
standard defect points, generation and annihilation points, and critical points
can be distinguished by coefficients of the Laurent series of the off-shell
characterized function at those singular points.
| [
{
"created": "Mon, 28 Nov 2022 16:42:37 GMT",
"version": "v1"
},
{
"created": "Sat, 3 Dec 2022 02:46:24 GMT",
"version": "v2"
},
{
"created": "Sat, 31 Dec 2022 09:51:40 GMT",
"version": "v3"
}
] | 2023-02-08 | [
[
"Fang",
"Chaoxi",
""
],
[
"Jiang",
"Jie",
""
],
[
"Zhang",
"Ming",
""
]
] | In the generalized off-shell free energy landscape, black holes can be treated as thermodynamic topological defects. The local topological properties of the spacetime can be reflected by the winding numbers at the defects, while the global topological nature can be classified by the topological number which is the sum of all local winding numbers. We propose that the winding numbers can be calculated via the residues of isolated one-order pole points of characterized functions constructed from the off-shell free energy. Using the residue method, we show that the topologies of black holes can be divided into three classes with the topological numbers being -1, 0, and 1, respectively, being consistent with the results obtained in [Phys. Rev. Lett. 129, 191101 (2022)] by using the topological current method. Moreover, we point out that standard defect points, generation and annihilation points, and critical points can be distinguished by coefficients of the Laurent series of the off-shell characterized function at those singular points. |
gr-qc/9907094 | The Mammouth | Tamath Rainsford (University of Adelaide) | Newtonian and Post-Newtonian approximations of the k = 0 Friedmann
Robertson Walker Cosmology | 11 pages, Latex, corrected typos | Gen.Rel.Grav. 32 (2000) 719-733 | 10.1023/A:1001971203318 | The University of Adelaide preprint 9929M84 | gr-qc | null | In a previous paper we derived a post-Newtonian approximation to cosmology
which, in contrast to former Newtonian and post-Newtonian cosmological
theories, has a well-posed initial value problem. In this paper, this new
post-Newtonian theory is compared with the fully general relativistic theory,
in the context of the k = 0 Friedmann Robertson Walker cosmologies. It is found
that the post-Newtonian theory reproduces the results of its general
relativistic counterpart, whilst the Newtonian theory does not.
| [
{
"created": "Wed, 28 Jul 1999 08:47:40 GMT",
"version": "v1"
},
{
"created": "Sun, 12 Sep 1999 07:41:45 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Rainsford",
"Tamath",
"",
"University of Adelaide"
]
] | In a previous paper we derived a post-Newtonian approximation to cosmology which, in contrast to former Newtonian and post-Newtonian cosmological theories, has a well-posed initial value problem. In this paper, this new post-Newtonian theory is compared with the fully general relativistic theory, in the context of the k = 0 Friedmann Robertson Walker cosmologies. It is found that the post-Newtonian theory reproduces the results of its general relativistic counterpart, whilst the Newtonian theory does not. |
2210.14574 | Marie-No\"elle C\'el\'erier | Marie-No\"elle C\'el\'erier | Fully integrated interior solutions of GR for stationary rigidly
rotating cylindrical perfect fluids | 11 pages, no figure | null | 10.1063/5.0131945 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In an important series of articles published during the 70's, Krasi\'nski
displayed a class of interior solutions of the Einstein field equations sourced
by a stationary isentropic rotating cylinder of perfect fluid. However, these
solutions depend on an unspecified arbitrary function, which lead the author to
claim that the equation of state of the fluid could not be obtained directly
from the field equations but had to be added by hand. In the present article,
we use a double ansatz which we have developed in 2021 and implemented at
length into a series of recent papers displaying exact interior solutions for a
stationary rotating cylindrically symmetric fluid with anisotropic pressure.
This ansatz allows us to obtain here a fully integrated class of solutions to
the Einstein equations, written with the use of very simple analytical
functions, and to show that the equation of state of the fluid follows
naturally from these field equations.
| [
{
"created": "Wed, 26 Oct 2022 09:14:26 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Aug 2023 07:31:49 GMT",
"version": "v2"
}
] | 2023-08-08 | [
[
"Célérier",
"Marie-Noëlle",
""
]
] | In an important series of articles published during the 70's, Krasi\'nski displayed a class of interior solutions of the Einstein field equations sourced by a stationary isentropic rotating cylinder of perfect fluid. However, these solutions depend on an unspecified arbitrary function, which lead the author to claim that the equation of state of the fluid could not be obtained directly from the field equations but had to be added by hand. In the present article, we use a double ansatz which we have developed in 2021 and implemented at length into a series of recent papers displaying exact interior solutions for a stationary rotating cylindrically symmetric fluid with anisotropic pressure. This ansatz allows us to obtain here a fully integrated class of solutions to the Einstein equations, written with the use of very simple analytical functions, and to show that the equation of state of the fluid follows naturally from these field equations. |
0910.2936 | Martin Bojowald | Martin Bojowald | Quantum geometry and quantum dynamics at the Planck scale | 10 pages, 2 figures, Proceedings of "The Planck Scale" (XXV Max Born
Symposium, Wroclaw) | AIP Conf. Proc.1196:62-71, 2009 | 10.1063/1.3284401 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Canonical quantum gravity provides insights into the quantum dynamics as well
as quantum geometry of space-time by its implications for constraints. Loop
quantum gravity in particular requires specific corrections due to its
quantization procedure, which also results in a discrete picture of space. The
corresponding changes compared to the classical behavior can most easily be
analyzed in isotropic models, but perturbations around them are more involved.
For one type of corrections, consistent equations have been found which shed
light on the underlying space-time structure at the Planck scale: not just
quantum dynamics but also the concept of space-time manifolds changes in
quantum gravity. Effective line elements provide indications for possible
relationships to other frameworks, such as non-commutative geometry.
| [
{
"created": "Thu, 15 Oct 2009 16:55:58 GMT",
"version": "v1"
}
] | 2015-05-14 | [
[
"Bojowald",
"Martin",
""
]
] | Canonical quantum gravity provides insights into the quantum dynamics as well as quantum geometry of space-time by its implications for constraints. Loop quantum gravity in particular requires specific corrections due to its quantization procedure, which also results in a discrete picture of space. The corresponding changes compared to the classical behavior can most easily be analyzed in isotropic models, but perturbations around them are more involved. For one type of corrections, consistent equations have been found which shed light on the underlying space-time structure at the Planck scale: not just quantum dynamics but also the concept of space-time manifolds changes in quantum gravity. Effective line elements provide indications for possible relationships to other frameworks, such as non-commutative geometry. |
0707.0409 | Pavel Krtous | David Kubiznak, Pavel Krtous | On conformal Killing-Yano tensors for Plebanski-Demianski family of
solutions | 7 pages, no figures | Phys.Rev.D76:084036,2007 | 10.1103/PhysRevD.76.084036 | Alberta-Thy-15-07 | gr-qc hep-th | null | We present the explicit expressions for the conformal Killing-Yano tensors
for the Plebanski-Demianski family of type D solutions in four dimensions. Some
physically important special cases are discussed in more detail. In particular,
it is demonstrated how the conformal Killing-Yano tensor becomes the
Killing-Yano tensor for the solutions without acceleration. A possible
generalization into higher dimensions is studied. Whereas the transition from
the nonaccelerating to accelerating solutions in four dimensions is achieved by
the conformal rescaling of the metric, we show that such a procedure is not
sufficiently general in higher dimensions - only the maximally symmetric
spacetimes in 'accelerated' coordinates are obtained.
| [
{
"created": "Tue, 3 Jul 2007 12:47:59 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Kubiznak",
"David",
""
],
[
"Krtous",
"Pavel",
""
]
] | We present the explicit expressions for the conformal Killing-Yano tensors for the Plebanski-Demianski family of type D solutions in four dimensions. Some physically important special cases are discussed in more detail. In particular, it is demonstrated how the conformal Killing-Yano tensor becomes the Killing-Yano tensor for the solutions without acceleration. A possible generalization into higher dimensions is studied. Whereas the transition from the nonaccelerating to accelerating solutions in four dimensions is achieved by the conformal rescaling of the metric, we show that such a procedure is not sufficiently general in higher dimensions - only the maximally symmetric spacetimes in 'accelerated' coordinates are obtained. |
gr-qc/0508116 | Roy Maartens | Richard A. Brown, Roy Maartens, Eleftherios Papantonopoulos, Vassilis
Zamarias | A late-accelerating universe with no dark energy - and a
finite-temperature big bang | revised title and minor improvements, additional references; to
appear JCAP | JCAP 0511 (2005) 008 | 10.1088/1475-7516/2005/11/008 | null | gr-qc astro-ph hep-th | null | Brane-world models offer the possibility of explaining the late acceleration
of the universe via infra-red modifications to General Relativity, rather than
a dark energy field. However, one also expects ultra-violet modifications to
General Relativity, when high-energy stringy effects in the early universe
begin to grow. We generalize the DGP brane-world model via an ultra-violet
modification, in the form of a Gauss-Bonnet term in the bulk action. The
combination of infra-red and ultra-violet modifications produces an intriguing
cosmology. The DGP feature of late-time acceleration without dark energy is
preserved, but there is an entirely new feature - there is no hot big bang in
the early universe. The universe starts with finite density and pressure, from
a "sudden" curvature singularity.
| [
{
"created": "Sun, 28 Aug 2005 14:22:51 GMT",
"version": "v1"
},
{
"created": "Mon, 31 Oct 2005 12:23:10 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Brown",
"Richard A.",
""
],
[
"Maartens",
"Roy",
""
],
[
"Papantonopoulos",
"Eleftherios",
""
],
[
"Zamarias",
"Vassilis",
""
]
] | Brane-world models offer the possibility of explaining the late acceleration of the universe via infra-red modifications to General Relativity, rather than a dark energy field. However, one also expects ultra-violet modifications to General Relativity, when high-energy stringy effects in the early universe begin to grow. We generalize the DGP brane-world model via an ultra-violet modification, in the form of a Gauss-Bonnet term in the bulk action. The combination of infra-red and ultra-violet modifications produces an intriguing cosmology. The DGP feature of late-time acceleration without dark energy is preserved, but there is an entirely new feature - there is no hot big bang in the early universe. The universe starts with finite density and pressure, from a "sudden" curvature singularity. |
gr-qc/9909037 | H. E. Puthoff, . D. | H. E. Puthoff | Polarizable-Vacuum (PV) representation of general relativity | corrected missing minus signs in eqns 68 and 71 | Found.Phys. 32 (2002) 927-943 | null | null | gr-qc | null | Standard pedagogy treats topics in general relativity (GR) in terms of tensor
formulations in curved space-time. Although mathematically straightforward, the
curved space-time approach can seem abstruse to beginning students due to the
degree of mathematical sophistication required. As a heuristic tool to provide
insight into what is meant by a curved metric, we present a polarizable-vacuum
(PV) representation of GR derived from a model by Dicke and related to the
"TH-epsilon-mu" formalism used in comparative studies of gravitational
theories.
| [
{
"created": "Fri, 10 Sep 1999 23:13:30 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Feb 2001 22:00:02 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Puthoff",
"H. E.",
""
]
] | Standard pedagogy treats topics in general relativity (GR) in terms of tensor formulations in curved space-time. Although mathematically straightforward, the curved space-time approach can seem abstruse to beginning students due to the degree of mathematical sophistication required. As a heuristic tool to provide insight into what is meant by a curved metric, we present a polarizable-vacuum (PV) representation of GR derived from a model by Dicke and related to the "TH-epsilon-mu" formalism used in comparative studies of gravitational theories. |
2209.06982 | Todd Oliynyk | Elliot Marshall, Todd A. Oliynyk | On the stability of relativistic perfect fluids with linear equations of
state $p=K\rho$ where $1/3<K<1$ | null | Lett. Math. Phys. 113 (2023), 102 | 10.1007/s11005-023-01722-7 | null | gr-qc math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For $1/3<K<1$, we consider the stability of two distinct families of
spatially homogeneous solutions to the relativistic Euler equations with a
linear equation of state $p=K\rho$ on exponentially expanding FLRW spacetimes.
The two families are distinguished by one being spatially isotropic while the
other is not. We establish the future stability of nonlinear perturbations of
the non-isotropic family for the full range of parameter values $1/3<K<1$,
which improves a previous stability result established by the second author
that required $K$ to lie in the restricted range $(1/3,1/2)$. As a first step
towards understanding the behaviour of nonlinear perturbations of the isotropic
family, we construct numerical solutions to the relativistic Euler equations
under a $\mathbb{T}^2$-symmetry assumption. These solutions are generated from
initial data at a fixed time that is chosen to be suitably close to the initial
data of an isotropic solution. Our numerical results reveal that, for the full
parameter range $1/3<K<1$, the density contrast $\frac{\partial_{x}\rho}{\rho}$
associated to a nonlinear perturbation of an isotropic solution develops steep
gradients near a finite number of spatial points where it becomes unbounded at
future timelike infinity. This behaviour, anticipated by Rendall in
\cite{Rendall:2004}, is of particular interest since it is not consistent with
the standard picture for inflation in cosmology.
| [
{
"created": "Thu, 15 Sep 2022 00:14:37 GMT",
"version": "v1"
}
] | 2024-03-20 | [
[
"Marshall",
"Elliot",
""
],
[
"Oliynyk",
"Todd A.",
""
]
] | For $1/3<K<1$, we consider the stability of two distinct families of spatially homogeneous solutions to the relativistic Euler equations with a linear equation of state $p=K\rho$ on exponentially expanding FLRW spacetimes. The two families are distinguished by one being spatially isotropic while the other is not. We establish the future stability of nonlinear perturbations of the non-isotropic family for the full range of parameter values $1/3<K<1$, which improves a previous stability result established by the second author that required $K$ to lie in the restricted range $(1/3,1/2)$. As a first step towards understanding the behaviour of nonlinear perturbations of the isotropic family, we construct numerical solutions to the relativistic Euler equations under a $\mathbb{T}^2$-symmetry assumption. These solutions are generated from initial data at a fixed time that is chosen to be suitably close to the initial data of an isotropic solution. Our numerical results reveal that, for the full parameter range $1/3<K<1$, the density contrast $\frac{\partial_{x}\rho}{\rho}$ associated to a nonlinear perturbation of an isotropic solution develops steep gradients near a finite number of spatial points where it becomes unbounded at future timelike infinity. This behaviour, anticipated by Rendall in \cite{Rendall:2004}, is of particular interest since it is not consistent with the standard picture for inflation in cosmology. |
1606.02302 | Carlos A. R. Herdeiro | Carlos A. R. Herdeiro, Eugen Radu | Static Einstein-Maxwell black holes with no spatial isometries in AdS
space | 5 pages, 4 figures; v2. change in title to comply with PRL
requirements. Version published in Physical Review Letters | Phys. Rev. Lett. 117, 221102 (2016) | 10.1103/PhysRevLett.117.221102 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explicitly construct static black hole solutions to the fully non-linear,
D=4, Einstein-Maxwell-AdS equations that have no continuous spatial symmetries.
These black holes have a smooth, topologically spherical horizon (section), but
without isometries, and approach, asymptotically, global AdS spacetime. They
are interpreted as bound states of a horizon with the Einstein-Maxwell-AdS
solitons recently discovered, for appropriate boundary data. In sharp contrast
with the uniqueness results for Minkowski electrovacuum, the existence of these
black holes shows that single, equilibrium, BH solutions in AdS-electrovacuum
admit an arbitrary multipole structure.
| [
{
"created": "Tue, 7 Jun 2016 20:00:02 GMT",
"version": "v1"
},
{
"created": "Thu, 24 Nov 2016 20:28:52 GMT",
"version": "v2"
}
] | 2016-11-30 | [
[
"Herdeiro",
"Carlos A. R.",
""
],
[
"Radu",
"Eugen",
""
]
] | We explicitly construct static black hole solutions to the fully non-linear, D=4, Einstein-Maxwell-AdS equations that have no continuous spatial symmetries. These black holes have a smooth, topologically spherical horizon (section), but without isometries, and approach, asymptotically, global AdS spacetime. They are interpreted as bound states of a horizon with the Einstein-Maxwell-AdS solitons recently discovered, for appropriate boundary data. In sharp contrast with the uniqueness results for Minkowski electrovacuum, the existence of these black holes shows that single, equilibrium, BH solutions in AdS-electrovacuum admit an arbitrary multipole structure. |
2012.03446 | Sergio Mendoza | E. Barrientos, S. Mendoza, P. Padilla | Extending Friedmann equations using fractional derivatives using a Last
Step Modification technique: the case of a matter dominated accelerated
expanding Universe | 13 pages, 3 figures, 3 tables. Accepted for publication in the
Journal Symmetry | Symmetry 2021, 13(2), 174 | 10.3390/sym13020174 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a toy model for extending the Friedmann equations of relativistic
cosmology using fractional derivatives. We do this by replacing the integer
derivatives, in a few well-known cosmological results with fractional
derivatives leaving their order as a free parameter. All this with the
intention to explain the current observed acceleration of the Universe. We
apply the Last Step Modification technique of fractional calculus to construct
some useful fractional equations of cosmology. The fits of the unknown
fractional derivative order and the fractional cosmographic parameters to SN Ia
data shows that this simple construction can explain the current accelerated
expansion of the Universe without the use of a dark energy component with a
MOND-like behaviour using Milgrom's acceleration constant which sheds light
into to the non-necessity of a dark matter component as well.
| [
{
"created": "Mon, 7 Dec 2020 04:48:44 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Jan 2021 23:20:32 GMT",
"version": "v2"
}
] | 2021-01-25 | [
[
"Barrientos",
"E.",
""
],
[
"Mendoza",
"S.",
""
],
[
"Padilla",
"P.",
""
]
] | We present a toy model for extending the Friedmann equations of relativistic cosmology using fractional derivatives. We do this by replacing the integer derivatives, in a few well-known cosmological results with fractional derivatives leaving their order as a free parameter. All this with the intention to explain the current observed acceleration of the Universe. We apply the Last Step Modification technique of fractional calculus to construct some useful fractional equations of cosmology. The fits of the unknown fractional derivative order and the fractional cosmographic parameters to SN Ia data shows that this simple construction can explain the current accelerated expansion of the Universe without the use of a dark energy component with a MOND-like behaviour using Milgrom's acceleration constant which sheds light into to the non-necessity of a dark matter component as well. |
1001.4148 | Khaled Saaidi | A. Aghamohammadi, Kh. Saaidi, M. R.Abolhasani, A.Vajdi | Spherical Symmetric Solution in f(R) Model Around Charged Black Hole | null | Int.J.Theor.Phys.49:709,2010 | 10.1007/s10773-010-0250-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A static, asymptotically flat, spherically symmetric solutions is
investigated in f(R) theories of gravity for a charged black hole. We have
studied the weak field limit of f(R) gravity for the some f(R) model such as
f(R) = R + epsilon h(R). In particular, weconsider the case lim_{R =0} {h(R)/
dh(R)/dR}=0 and find the space time metric for f(R) = R + {mu}^{4} /R and f(R)
= R^{1-epsilon} theories of gravity far away a charged mass point.
| [
{
"created": "Sat, 23 Jan 2010 12:14:25 GMT",
"version": "v1"
}
] | 2011-09-13 | [
[
"Aghamohammadi",
"A.",
""
],
[
"Saaidi",
"Kh.",
""
],
[
"Abolhasani",
"M. R.",
""
],
[
"Vajdi",
"A.",
""
]
] | A static, asymptotically flat, spherically symmetric solutions is investigated in f(R) theories of gravity for a charged black hole. We have studied the weak field limit of f(R) gravity for the some f(R) model such as f(R) = R + epsilon h(R). In particular, weconsider the case lim_{R =0} {h(R)/ dh(R)/dR}=0 and find the space time metric for f(R) = R + {mu}^{4} /R and f(R) = R^{1-epsilon} theories of gravity far away a charged mass point. |
1907.10694 | Alexander Oliveros < | A. Oliveros and Hern\'an E. Noriega | Constant-roll inflation driven by a scalar field with non-minimal
derivative coupling | 15 pages, 6 figures, accepted for publication in Int. J. Mod. Phys. D | null | 10.1142/S0218271819501591 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we study constant-roll inflation driven by a scalar field with
non-minimal derivative coupling to gravity, via the Einstein tensor. This model
contains a free parameter, $\eta$, which quantifies the non-minimal derivative
coupling and a parameter $\alpha$ which characterize the constant-roll
condition. In this scenario, using the Hamilton-Jacobi-like formalism, an
ansatz for the Hubble parameter (as a function of the scalar field) and some
restrictions on the model parameters, we found new exact solutions for the
inflaton potential which include power-law, de Sitter, quadratic hilltop and
natural inflation, among others. Additionally, a phase space analysis was
performed and it is shown that the exact solutions associated to natural
inflation and a "$\cosh$-type" potential, are attractors.
| [
{
"created": "Wed, 24 Jul 2019 20:06:36 GMT",
"version": "v1"
}
] | 2019-10-23 | [
[
"Oliveros",
"A.",
""
],
[
"Noriega",
"Hernán E.",
""
]
] | In this work, we study constant-roll inflation driven by a scalar field with non-minimal derivative coupling to gravity, via the Einstein tensor. This model contains a free parameter, $\eta$, which quantifies the non-minimal derivative coupling and a parameter $\alpha$ which characterize the constant-roll condition. In this scenario, using the Hamilton-Jacobi-like formalism, an ansatz for the Hubble parameter (as a function of the scalar field) and some restrictions on the model parameters, we found new exact solutions for the inflaton potential which include power-law, de Sitter, quadratic hilltop and natural inflation, among others. Additionally, a phase space analysis was performed and it is shown that the exact solutions associated to natural inflation and a "$\cosh$-type" potential, are attractors. |
gr-qc/9310004 | Khatsymovsky | V. Khatsymovsky | Regge calculus in the canonical form | 24 pages,Plain LaTeX,BINP 93-42 | Gen.Rel.Grav. 27 (1995) 583-603 | 10.1007/BF02108063 | null | gr-qc | null | (3+1) (continuous time) Regge calculus is reduced to Hamiltonian form. The
constraints are classified, classical and quantum consequences are discussed.
As basic variables connection matrices and antisymmetric area tensors are used
supplemented with appropriate bilinear constraints. In these variables the
action can be made quasipolinomial with $\arcsin$ as the only deviation from
polinomiality. In comparison with analogous formalism in the continuum theory
classification of constraints changes: some of them disappear, the part of I
class constraints including Hamiltonian one become II class (and vice versa,
some new constraints arise and some II class constraints become I class). As a
result, the number of the degrees of freedom coincides with the number of links
in 3-dimensional leaf of foliation. Moreover, in empty space classical dynamics
is trivial: the scale of timelike links become zero and spacelike links are
constant.
| [
{
"created": "Sun, 3 Oct 1993 12:32:50 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Khatsymovsky",
"V.",
""
]
] | (3+1) (continuous time) Regge calculus is reduced to Hamiltonian form. The constraints are classified, classical and quantum consequences are discussed. As basic variables connection matrices and antisymmetric area tensors are used supplemented with appropriate bilinear constraints. In these variables the action can be made quasipolinomial with $\arcsin$ as the only deviation from polinomiality. In comparison with analogous formalism in the continuum theory classification of constraints changes: some of them disappear, the part of I class constraints including Hamiltonian one become II class (and vice versa, some new constraints arise and some II class constraints become I class). As a result, the number of the degrees of freedom coincides with the number of links in 3-dimensional leaf of foliation. Moreover, in empty space classical dynamics is trivial: the scale of timelike links become zero and spacelike links are constant. |
2103.14582 | Roberto Casadio | Roberto Casadio | A quantum bound on the compactness | 8 pages, LaTeX, one figure, references and comments added | null | 10.1140/epjc/s10052-021-09980-2 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We present a simple quantum description of the gravitational collapse of a
ball of dust which excludes those states whose width is arbitrarily smaller
than the gravitational radius of the matter source and supports the conclusion
that black holes are macroscopic extended objects. We also comment briefly on
the relevance of this result for the ultraviolet self-completion of gravity and
the corpuscular picture of black holes.
| [
{
"created": "Fri, 26 Mar 2021 16:44:05 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Apr 2021 05:53:06 GMT",
"version": "v2"
},
{
"created": "Tue, 8 Jun 2021 15:42:04 GMT",
"version": "v3"
},
{
"created": "Tue, 28 Dec 2021 15:35:11 GMT",
"version": "v4"
}
] | 2022-01-26 | [
[
"Casadio",
"Roberto",
""
]
] | We present a simple quantum description of the gravitational collapse of a ball of dust which excludes those states whose width is arbitrarily smaller than the gravitational radius of the matter source and supports the conclusion that black holes are macroscopic extended objects. We also comment briefly on the relevance of this result for the ultraviolet self-completion of gravity and the corpuscular picture of black holes. |
gr-qc/9908045 | Don Marolf | Donald Marolf | String/M-branes for Relativists | 50 pages, 6 figures, For the Proceedings of the 3rd Mexican School on
Gravitation and Mathematical Physics (Mazatl\'an, Mexico, Nov. 1998)
Kaluza-Klein reduction or 3-form corrected | null | null | SU-GP-99/8-3 | gr-qc hep-th | null | These notes present an introduction to branes in ten and eleven dimensional
supergravity and string/M-theory which is geared to an audience of traditional
relativists, especially graduate students and others with little background in
supergravity. They are designed as a tutorial and not as a thorough review of
the subject; as a result, many topics of current interest are not addressed.
However, a guide to further reading is included. The presentation begins with
eleven dimensional supergravity, stressing its relation to 3+1 Einstein-Maxwell
theory. The notion of Kaluza-Klein compactification is then introduced, and is
used to relate the eleven dimensional discussion to supergravity in 9+1
dimensions and to string theory. The focus is on type IIA supergravity, but the
type IIB theory is also addressed, as is the T-duality symmetry that relates
them. Branes in both 10+1 and 9+1 dimensions are included. Finally, although
the details are not discussed, a few comments are provided on the relation
between supergravity and string perturbation theory and on black hole entropy.
The goal is to provide traditional relativists with a kernel of knowledge from
which to grow their understanding of branes and strings.
| [
{
"created": "Mon, 16 Aug 1999 18:17:11 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Dec 1999 04:53:23 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Marolf",
"Donald",
""
]
] | These notes present an introduction to branes in ten and eleven dimensional supergravity and string/M-theory which is geared to an audience of traditional relativists, especially graduate students and others with little background in supergravity. They are designed as a tutorial and not as a thorough review of the subject; as a result, many topics of current interest are not addressed. However, a guide to further reading is included. The presentation begins with eleven dimensional supergravity, stressing its relation to 3+1 Einstein-Maxwell theory. The notion of Kaluza-Klein compactification is then introduced, and is used to relate the eleven dimensional discussion to supergravity in 9+1 dimensions and to string theory. The focus is on type IIA supergravity, but the type IIB theory is also addressed, as is the T-duality symmetry that relates them. Branes in both 10+1 and 9+1 dimensions are included. Finally, although the details are not discussed, a few comments are provided on the relation between supergravity and string perturbation theory and on black hole entropy. The goal is to provide traditional relativists with a kernel of knowledge from which to grow their understanding of branes and strings. |
2112.08413 | Carlos Palenzuela | C. Palenzuela, R. Aguilera-Miret, F. Carrasco, R. Ciolfi, J.V.
Kalinani, W. Kastaun, B. Mi\~nano and D. Vigan\`o | Turbulent magnetic field amplification in binary neutron star mergers | 22 pages, 17 figures, version matching the published article | null | 10.1103/PhysRevD.106.023013 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Magnetic fields are expected to play a key role in the dynamics and the
ejection mechanisms that accompany the merger of two neutron stars. General
relativistic magnetohydrodynamic (MHD) simulations offer a unique opportunity
to unravel the details of the ongoing physical processes. Nevertheless, current
numerical studies are severely limited by the fact that any affordable
resolution remains insufficient to fully capture the small-scale dynamo,
initially triggered by the Kelvin-Helmholtz instability, and later sourced by
several MHD processes involving differential rotation. Here, we alleviate this
limitation by using explicit large-eddy simulations, a technique where the
unresolved dynamics occurring at the sub-grid scales (SGS) is modeled by extra
terms, which are functions of the resolved fields and their derivatives. The
combination of high-order numerical schemes, high resolutions, and the gradient
SGS model allow us to capture the small-scale dynamos produced during the
binary neutron star mergers. Here we follow the first 50 milliseconds after the
merger and, for the first time, we find numerical convergence on the magnetic
field amplification, in terms of integrated energy and spectral distribution
over spatial scales. We also find that the average intensity of the magnetic
field in the remnant saturates at $\sim 10^{16}$~G around $5$~ms after the
merger. After $20-30$~ms, both toroidal and poloidal magnetic field components
grow continuously, fed by the winding mechanism that provides a slow inverse
cascade. We find no clear hints for magneto-rotational instabilities, and no
significant impact of the magnetic field on the redistribution of angular
momentum in the remnant in our simulations, probably due to the very turbulent
and dynamical topology of the magnetic field at all stages, with small-scale
components largely dominating over the large-scale ones.
| [
{
"created": "Wed, 15 Dec 2021 19:02:31 GMT",
"version": "v1"
},
{
"created": "Sun, 3 Jul 2022 07:41:52 GMT",
"version": "v2"
}
] | 2022-07-27 | [
[
"Palenzuela",
"C.",
""
],
[
"Aguilera-Miret",
"R.",
""
],
[
"Carrasco",
"F.",
""
],
[
"Ciolfi",
"R.",
""
],
[
"Kalinani",
"J. V.",
""
],
[
"Kastaun",
"W.",
""
],
[
"Miñano",
"B.",
""
],
[
"Viganò",
"D.",
""
]
] | Magnetic fields are expected to play a key role in the dynamics and the ejection mechanisms that accompany the merger of two neutron stars. General relativistic magnetohydrodynamic (MHD) simulations offer a unique opportunity to unravel the details of the ongoing physical processes. Nevertheless, current numerical studies are severely limited by the fact that any affordable resolution remains insufficient to fully capture the small-scale dynamo, initially triggered by the Kelvin-Helmholtz instability, and later sourced by several MHD processes involving differential rotation. Here, we alleviate this limitation by using explicit large-eddy simulations, a technique where the unresolved dynamics occurring at the sub-grid scales (SGS) is modeled by extra terms, which are functions of the resolved fields and their derivatives. The combination of high-order numerical schemes, high resolutions, and the gradient SGS model allow us to capture the small-scale dynamos produced during the binary neutron star mergers. Here we follow the first 50 milliseconds after the merger and, for the first time, we find numerical convergence on the magnetic field amplification, in terms of integrated energy and spectral distribution over spatial scales. We also find that the average intensity of the magnetic field in the remnant saturates at $\sim 10^{16}$~G around $5$~ms after the merger. After $20-30$~ms, both toroidal and poloidal magnetic field components grow continuously, fed by the winding mechanism that provides a slow inverse cascade. We find no clear hints for magneto-rotational instabilities, and no significant impact of the magnetic field on the redistribution of angular momentum in the remnant in our simulations, probably due to the very turbulent and dynamical topology of the magnetic field at all stages, with small-scale components largely dominating over the large-scale ones. |
gr-qc/0601077 | Emanuele Berti | Emanuele Berti, Vitor Cardoso, Clifford M. Will | Considerations on the excitation of black hole quasinormal modes | 11 pages, 2 figures, proceedings of the 7th International Conference
of the Hellenic Astronomical Society. Complements section VB of gr-qc/0512160 | null | 10.1063/1.2348047 | null | gr-qc astro-ph | null | We provide some considerations on the excitation of black hole quasinormal
modes (QNMs) in different physical scenarios. Considering a simple model in
which a stream of particles accretes onto a black hole, we show that resonant
QNM excitation by hyperaccretion requires a significant amount of fine-tuning,
and is quite unlikely to occur in nature. Then we summarize and discuss present
estimates of black hole QNM excitation from gravitational collapse, distorted
black holes and head-on black hole collisions. We emphasize the areas that, in
our opinion, are in urgent need of further investigation from the point of view
of gravitational wave source modeling.
| [
{
"created": "Wed, 18 Jan 2006 18:57:13 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Berti",
"Emanuele",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Will",
"Clifford M.",
""
]
] | We provide some considerations on the excitation of black hole quasinormal modes (QNMs) in different physical scenarios. Considering a simple model in which a stream of particles accretes onto a black hole, we show that resonant QNM excitation by hyperaccretion requires a significant amount of fine-tuning, and is quite unlikely to occur in nature. Then we summarize and discuss present estimates of black hole QNM excitation from gravitational collapse, distorted black holes and head-on black hole collisions. We emphasize the areas that, in our opinion, are in urgent need of further investigation from the point of view of gravitational wave source modeling. |
1910.00315 | Tigran Tchrakian | D.H. Tchrakian | A remark on black holes of Chern-Simons gravities in $2n+1$ dimensions:
$n=1,2,3$ | 8 pages | null | 10.1142/S0217751X20500220 | DIAS-STP-19-07 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that Chern-Simons gravities in $2n+1$ dimensions admit solutions
described by the same lapse function which describes the BTZ black hole in the
$n=1$ case. This has been carried out explicitly for $n=1,2,3$. Moreover, it is
seen that these solutions are unique.
| [
{
"created": "Tue, 1 Oct 2019 11:47:38 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Oct 2019 10:13:43 GMT",
"version": "v2"
},
{
"created": "Wed, 5 Feb 2020 14:16:52 GMT",
"version": "v3"
},
{
"created": "Fri, 28 Feb 2020 12:15:43 GMT",
"version": "v4"
}
] | 2020-04-15 | [
[
"Tchrakian",
"D. H.",
""
]
] | It is shown that Chern-Simons gravities in $2n+1$ dimensions admit solutions described by the same lapse function which describes the BTZ black hole in the $n=1$ case. This has been carried out explicitly for $n=1,2,3$. Moreover, it is seen that these solutions are unique. |
gr-qc/0511132 | Edgard Casal de Rey Neto | Edgard Casal de Rey Neto | Braneworld with Induced Axial Symmetry | 3 pages, one figure, typos corrected, to apear in the special issue
of Brazilian Journal of Physics dedicated to the conference 100 years of
relativity, Sao Paulo, Brazil, 2005 | Braz.J.Phys. 35 (2005) 1131-1132 | null | null | gr-qc hep-th | null | We take arbitrary gravitational perturbations of a 5d spacetime and reduce it
to the form an axially symmetric warped braneworld. Then, we write the filed
equations for the linearized gravity perturbations. We obtain the equations
that describes the graviton, gravivector and the graviscalar fluctuations and
analyse the effects of the Schr\"odinger potentials that appear in these
equations.
| [
{
"created": "Thu, 24 Nov 2005 12:17:49 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Dec 2005 13:09:27 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Neto",
"Edgard Casal de Rey",
""
]
] | We take arbitrary gravitational perturbations of a 5d spacetime and reduce it to the form an axially symmetric warped braneworld. Then, we write the filed equations for the linearized gravity perturbations. We obtain the equations that describes the graviton, gravivector and the graviscalar fluctuations and analyse the effects of the Schr\"odinger potentials that appear in these equations. |
0801.3407 | Serge Reynaud | Serge Reynaud and Marc-Thierry Jaekel | Tests of general relativity in the solar system | Notes of a lecture given during the International School of Physics
Enrico Fermi on Atom Optics and Space Physics (Varenna, July 2007) | Proceedings of the International School of Physics "Enrico Fermi"
(2009) Volume 168: Atom Optics and Space Physics pp 203--217 | 10.3254/978-1-58603-990-5-203 | null | gr-qc astro-ph quant-ph | null | Tests of gravity performed in the solar system show a good agreement with
general relativity. The latter is however challenged by observations at larger,
galactic and cosmic, scales which are presently cured by introducing "dark
matter" or "dark energy". A few measurements in the solar system, particularly
the so-called "Pioneer anomaly", might also be pointing at a modification of
gravity law at ranges of the order of the size of the solar system. The present
lecture notes discuss the current status of tests of general relativity in the
solar system. They describe metric extensions of general relativity which have
the capability to preserve compatibility with existing gravity tests while
opening free space for new phenomena. They present arguments for new mission
designs and new space technologies as well as for having a new look on data of
existing or future experiments.
| [
{
"created": "Tue, 22 Jan 2008 16:33:26 GMT",
"version": "v1"
}
] | 2023-04-14 | [
[
"Reynaud",
"Serge",
""
],
[
"Jaekel",
"Marc-Thierry",
""
]
] | Tests of gravity performed in the solar system show a good agreement with general relativity. The latter is however challenged by observations at larger, galactic and cosmic, scales which are presently cured by introducing "dark matter" or "dark energy". A few measurements in the solar system, particularly the so-called "Pioneer anomaly", might also be pointing at a modification of gravity law at ranges of the order of the size of the solar system. The present lecture notes discuss the current status of tests of general relativity in the solar system. They describe metric extensions of general relativity which have the capability to preserve compatibility with existing gravity tests while opening free space for new phenomena. They present arguments for new mission designs and new space technologies as well as for having a new look on data of existing or future experiments. |
gr-qc/0611142 | Luc Blanchet | Luc Blanchet | General Relativistic Dynamics of Compact Binary Systems | 13 pages, to appear in the special issue of the Comptes rendus de
l'Academie des Sciences de Paris on "Observations of black holes and extreme
gravitational events", edited by Daniel Rouan | ComptesRendusPhysique8:57-68,2007 | 10.1016/j.crhy.2006.11.004 | null | gr-qc | null | The equations of motion of compact binary systems have been derived in the
post-Newtonian (PN) approximation of general relativity. The current level of
accuracy is 3.5PN order. The conservative part of the equations of motion
(neglecting the radiation reaction damping terms) is deducible from a
generalized Lagrangian in harmonic coordinates, or equivalently from an
ordinary Hamiltonian in ADM coordinates. As an application we investigate the
problem of the dynamical stability of circular binary orbits against
gravitational perturbations up to the 3PN order. We find that there is no
innermost stable circular orbit or ISCO at the 3PN order for equal masses.
| [
{
"created": "Mon, 27 Nov 2006 18:54:59 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Blanchet",
"Luc",
""
]
] | The equations of motion of compact binary systems have been derived in the post-Newtonian (PN) approximation of general relativity. The current level of accuracy is 3.5PN order. The conservative part of the equations of motion (neglecting the radiation reaction damping terms) is deducible from a generalized Lagrangian in harmonic coordinates, or equivalently from an ordinary Hamiltonian in ADM coordinates. As an application we investigate the problem of the dynamical stability of circular binary orbits against gravitational perturbations up to the 3PN order. We find that there is no innermost stable circular orbit or ISCO at the 3PN order for equal masses. |
gr-qc/0311011 | Daniel Grumiller | D. Grumiller | Deformations of the Schwarzschild Black Hole | 6 pages, 3 figures, invited contribution to the QG1 session at MGX,
v2: updated affiliation | null | null | ESI-1404, TUW-03-34 | gr-qc astro-ph hep-th | null | Due to its large number of symmetries the Schwarzschild Black Hole can be
described by a specific two-dimensional dilaton gravity model. After reviewing
classical, semi-classical and quantum properties and a brief discussion of
virtual black holes deformations are studied: the first part is devoted to
deformations of the Lorentz-symmetry, the second part to dynamical deformations
and its role for the long time evaporation of the Schwarzschild Black Hole.
| [
{
"created": "Tue, 4 Nov 2003 18:43:59 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Dec 2003 10:18:28 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Grumiller",
"D.",
""
]
] | Due to its large number of symmetries the Schwarzschild Black Hole can be described by a specific two-dimensional dilaton gravity model. After reviewing classical, semi-classical and quantum properties and a brief discussion of virtual black holes deformations are studied: the first part is devoted to deformations of the Lorentz-symmetry, the second part to dynamical deformations and its role for the long time evaporation of the Schwarzschild Black Hole. |
2004.03912 | Masroor C. Pookkillath | Masroor C. Pookkillath, Antonio De Felice, Alexei A. Starobinsky | Anisotropic instability in a higher order gravity theory | 15 pages, 2 figures, accepted by JCAP, matches with accepted version | JCAP07(2020)041 | 10.1088/1475-7516/2020/07/041 | YITP-20-43 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study a metric cubic gravity theory considering odd-parity modes of linear
inhomogeneous perturbations on a spatially homogeneous Bianchi type I manifold
close to the isotropic de Sitter spacetime. We show that in the regime of small
anisotropy, the theory possesses new degrees of freedom compared to General
Relativity, whose kinetic energy vanishes in the limit of exact isotropy. From
the mass dispersion relation we show that such theory always possesses at least
one ghost mode as well as a very short-time-scale (compared to the Hubble time)
classical tachyonic (or ghost-tachyonic) instability. In order to confirm our
analytic analysis, we also solve the equations of motion numerically and we
find that this instability is developed well before a single e-fold of the
scale factor. This shows that this gravity theory, as it is, cannot be used to
construct viable cosmological models.
| [
{
"created": "Wed, 8 Apr 2020 09:53:09 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Jul 2020 09:11:28 GMT",
"version": "v2"
}
] | 2020-07-20 | [
[
"Pookkillath",
"Masroor C.",
""
],
[
"De Felice",
"Antonio",
""
],
[
"Starobinsky",
"Alexei A.",
""
]
] | We study a metric cubic gravity theory considering odd-parity modes of linear inhomogeneous perturbations on a spatially homogeneous Bianchi type I manifold close to the isotropic de Sitter spacetime. We show that in the regime of small anisotropy, the theory possesses new degrees of freedom compared to General Relativity, whose kinetic energy vanishes in the limit of exact isotropy. From the mass dispersion relation we show that such theory always possesses at least one ghost mode as well as a very short-time-scale (compared to the Hubble time) classical tachyonic (or ghost-tachyonic) instability. In order to confirm our analytic analysis, we also solve the equations of motion numerically and we find that this instability is developed well before a single e-fold of the scale factor. This shows that this gravity theory, as it is, cannot be used to construct viable cosmological models. |
1109.6798 | J. A. de Freitas Pacheco | J.A. de Freitas Pacheco | Relativistic Accretion into a Reissner-Nordstr\"om Black Hole Revisited | 13 pages - Accepted for publication in Journal of Thermodynamics | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The accretion of relativistic and non-relativistic fluids into a
Reissner-Nordstr\"om black hole is revisited. The position of the critical
point, the flow velocity at this point and the accretion rate are only slightly
affected with respect to the Schwarzschild case when the fluid is
non-relativistic. On the contrary, relativistic fluids cross the critical point
always subsonically. In this case, the sonic point is located near the event
horizon, which is crossed by the fluid with a velocity less than the light
speed. The accretion rate of relativistic fluids by a Reissner-Nordstr\"om
black hole is reduced with respect to those estimated for uncharged black
holes, being about 60% less for the extreme case (charge-to-mass ratio equal to
one).
| [
{
"created": "Fri, 30 Sep 2011 11:39:02 GMT",
"version": "v1"
}
] | 2011-10-03 | [
[
"Pacheco",
"J. A. de Freitas",
""
]
] | The accretion of relativistic and non-relativistic fluids into a Reissner-Nordstr\"om black hole is revisited. The position of the critical point, the flow velocity at this point and the accretion rate are only slightly affected with respect to the Schwarzschild case when the fluid is non-relativistic. On the contrary, relativistic fluids cross the critical point always subsonically. In this case, the sonic point is located near the event horizon, which is crossed by the fluid with a velocity less than the light speed. The accretion rate of relativistic fluids by a Reissner-Nordstr\"om black hole is reduced with respect to those estimated for uncharged black holes, being about 60% less for the extreme case (charge-to-mass ratio equal to one). |
2310.08518 | Horacio Santana Vieira | M. Abu-Saleem, H. S. Vieira, L. H. C. Borges | On the five-dimensional non-extremal Reissner-Nordstr\"{o}m black hole:
Retractions and scalar quasibound states | 17 pages, 4 figures. Matches published version in Universe | Universe 10, 267 (2024) | 10.3390/universe10060267 | null | gr-qc math.GT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we examine the role played by topology, and some specific
boundary conditions as well, on the physics of a higher-dimensional black hole.
We analyze the line element of a five-dimensional non-extremal
Reissner-Nordstr\"{o}m black hole to obtain a new family of subspaces that are
types of strong retractions and deformations, and then we extend these results
to higher dimensions in order to deduce the relationship between various types
of transformations. We also study the scalar field perturbations in the
background under consideration and obtain an analytical expression for the
quasibound state frequencies by using the Vieira-Bezerra-Kokkotas approach,
which uses the polynomial conditions of the general Heun functions, and then we
discuss the stability of the system and present the radial eigenfunctions. Our
main goal is to discuss the physical meaning of these mathematical applications
in such higher-dimensional effective metric.
| [
{
"created": "Thu, 12 Oct 2023 17:11:21 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Jul 2024 20:31:25 GMT",
"version": "v2"
}
] | 2024-07-17 | [
[
"Abu-Saleem",
"M.",
""
],
[
"Vieira",
"H. S.",
""
],
[
"Borges",
"L. H. C.",
""
]
] | In this paper, we examine the role played by topology, and some specific boundary conditions as well, on the physics of a higher-dimensional black hole. We analyze the line element of a five-dimensional non-extremal Reissner-Nordstr\"{o}m black hole to obtain a new family of subspaces that are types of strong retractions and deformations, and then we extend these results to higher dimensions in order to deduce the relationship between various types of transformations. We also study the scalar field perturbations in the background under consideration and obtain an analytical expression for the quasibound state frequencies by using the Vieira-Bezerra-Kokkotas approach, which uses the polynomial conditions of the general Heun functions, and then we discuss the stability of the system and present the radial eigenfunctions. Our main goal is to discuss the physical meaning of these mathematical applications in such higher-dimensional effective metric. |
2311.09921 | Ronaldas Macas | Ronaldas Macas, Andrew Lundgren, Gregory Ashton | Revisiting the evidence for precession in GW200129 with machine learning
noise mitigation | Updating with the journal-reviewed version. 8 pages, 6 figures. Data
frame available at DOI: 10.5281/zenodo.10143337 | Phys. Rev. D 109, 062006 (2024) | 10.1103/PhysRevD.109.062006 | null | gr-qc astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | GW200129 is claimed to be the first-ever observation of the spin-disk orbital
precession detected with gravitational waves (GWs) from an individual binary
system. However, this claim warrants a cautious evaluation because the GW event
coincided with a broadband noise disturbance in LIGO Livingston caused by the
45 MHz electro-optic modulator system. In this paper, we present a
state-of-the-art neural network that is able to model and mitigate the
broadband noise from the LIGO Livingston interferometer. We also demonstrate
that our neural network mitigates the noise better than the algorithm used by
the LIGO-Virgo-KAGRA collaboration. Finally, we re-analyse GW200129 with the
improved data quality and show that the evidence for precession is still
observed.
| [
{
"created": "Thu, 16 Nov 2023 14:21:11 GMT",
"version": "v1"
},
{
"created": "Sat, 23 Mar 2024 08:43:28 GMT",
"version": "v2"
}
] | 2024-03-26 | [
[
"Macas",
"Ronaldas",
""
],
[
"Lundgren",
"Andrew",
""
],
[
"Ashton",
"Gregory",
""
]
] | GW200129 is claimed to be the first-ever observation of the spin-disk orbital precession detected with gravitational waves (GWs) from an individual binary system. However, this claim warrants a cautious evaluation because the GW event coincided with a broadband noise disturbance in LIGO Livingston caused by the 45 MHz electro-optic modulator system. In this paper, we present a state-of-the-art neural network that is able to model and mitigate the broadband noise from the LIGO Livingston interferometer. We also demonstrate that our neural network mitigates the noise better than the algorithm used by the LIGO-Virgo-KAGRA collaboration. Finally, we re-analyse GW200129 with the improved data quality and show that the evidence for precession is still observed. |
0708.0883 | Carlo Rovelli | Emanuele Alesci, Carlo Rovelli | The complete LQG propagator: I. Difficulties with the Barrett-Crane
vertex | 31 pages | Phys.Rev.D76:104012,2007 | 10.1103/PhysRevD.76.104012 | null | gr-qc | null | Some components of the graviton two-point function have been recently
computed in the context of loop quantum gravity, using the spinfoam
Barrett-Crane vertex. We complete the calculation of the remaining components.
We find that, under our assumptions, the Barrett-Crane vertex does not yield
the correct long distance limit. We argue that the problem is general and can
be traced to the intertwiner-independence of the Barrett-Crane vertex, and
therefore to the well-known mismatch between the Barrett-Crane formalism and
the standard canonical spin networks. In a companion paper we illustrate the
asymptotic behavior of a vertex amplitude that can correct this difficulty.
| [
{
"created": "Tue, 7 Aug 2007 07:00:16 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Alesci",
"Emanuele",
""
],
[
"Rovelli",
"Carlo",
""
]
] | Some components of the graviton two-point function have been recently computed in the context of loop quantum gravity, using the spinfoam Barrett-Crane vertex. We complete the calculation of the remaining components. We find that, under our assumptions, the Barrett-Crane vertex does not yield the correct long distance limit. We argue that the problem is general and can be traced to the intertwiner-independence of the Barrett-Crane vertex, and therefore to the well-known mismatch between the Barrett-Crane formalism and the standard canonical spin networks. In a companion paper we illustrate the asymptotic behavior of a vertex amplitude that can correct this difficulty. |
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