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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1505.07441
|
Steven Carlip
|
S. Carlip
|
Can gravitational microlensing by vacuum fluctuations be observed?
|
8 pages, 1 figure
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Although the prospect is more plausible than it might appear, the answer to
the title question is, unfortunately, "probably not." Quantum fluctuations of
vacuum energy can focus light, and while the effect is tiny, the distribution
of fluctuations is highly non-Gaussian, offering hope that relatively rare
"large" fluctuations might be observable. I show that although gravitational
microlensing by such fluctuations become important at scales much larger than
the Planck length, the possibility of direct observation remains remote,
although there is a small chance that cumulative effects over cosmological
distances might be detectable. The effect is sensitive to the size of the
Planck scale, however, and could offer a new test of TeV-scale gravity.
|
[
{
"created": "Wed, 27 May 2015 19:28:05 GMT",
"version": "v1"
}
] |
2015-05-28
|
[
[
"Carlip",
"S.",
""
]
] |
Although the prospect is more plausible than it might appear, the answer to the title question is, unfortunately, "probably not." Quantum fluctuations of vacuum energy can focus light, and while the effect is tiny, the distribution of fluctuations is highly non-Gaussian, offering hope that relatively rare "large" fluctuations might be observable. I show that although gravitational microlensing by such fluctuations become important at scales much larger than the Planck length, the possibility of direct observation remains remote, although there is a small chance that cumulative effects over cosmological distances might be detectable. The effect is sensitive to the size of the Planck scale, however, and could offer a new test of TeV-scale gravity.
|
0906.3806
|
Kourosh Nozari
|
Kourosh Nozari and Faeze Kiani
|
Dynamical-Screening and the Phantom-Like Effects in a DGP-Inspired
$F(R,\phi)$ Model
|
21 pages, 8 eps figures, to appear in JCAP
|
JCAP 0907:010,2009
|
10.1088/1475-7516/2009/07/010
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Based on the Lue-Starkman conjecture on the dynamical screening of the brane
cosmological constant in the DGP scenario, we extend this proposal to a general
DGP-inspired $F(R,\phi)$ Model. We show that modification of the induced
gravity and its coupling to a quintessence field localized on the brane,
affects the screening of the brane cosmological constant and also phantom-like
behavior on the brane. We extend our study to possible modification of the
induced gravity on the brane and for clarification some specific examples are
presented. As a result, phantom-like behavior can be realized in this setup
without violating the null energy condition at least in some subspaces of the
model parameter space. The key result of our study is the fact that a
DGP-inspired $F(R,\phi)$ scenario has the best fit with LCDM and recent
observations than other alternative theories.
|
[
{
"created": "Sat, 20 Jun 2009 12:57:12 GMT",
"version": "v1"
}
] |
2009-09-24
|
[
[
"Nozari",
"Kourosh",
""
],
[
"Kiani",
"Faeze",
""
]
] |
Based on the Lue-Starkman conjecture on the dynamical screening of the brane cosmological constant in the DGP scenario, we extend this proposal to a general DGP-inspired $F(R,\phi)$ Model. We show that modification of the induced gravity and its coupling to a quintessence field localized on the brane, affects the screening of the brane cosmological constant and also phantom-like behavior on the brane. We extend our study to possible modification of the induced gravity on the brane and for clarification some specific examples are presented. As a result, phantom-like behavior can be realized in this setup without violating the null energy condition at least in some subspaces of the model parameter space. The key result of our study is the fact that a DGP-inspired $F(R,\phi)$ scenario has the best fit with LCDM and recent observations than other alternative theories.
|
1511.04418
|
Abhijit Mandal
|
Abhijit Mandal and Ritabrata Biswas
|
Quantum Corrected Schwarzschild Black Hole: Inner Horizon Thermodynamic
Behaviors
|
7 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1511.00653; text overlap with arXiv:gr-qc/9704072 by other authors
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The thermodynamic properties of Cauchy horizon is a matter of interest. Event
horizon and Cauchy horizon together can enlighten us about the micro-states of
a black hole. In addition, if we consider a black hole metric modified with
quantum terms, which is not forcing the geodesics to focus at a singularity,
the study of horizons becomes much more interesting. The spacelike behavior
inside the Cauchy horizon has a deep impact on the related thermodynamics. We
analyze different thermodynamic product to check whether a right left string
theory mode's addition type representation for the concerned thermodynamic
parameters is possible or not. Stability of Cauchy horizon is studied.
|
[
{
"created": "Fri, 13 Nov 2015 20:15:19 GMT",
"version": "v1"
}
] |
2015-11-16
|
[
[
"Mandal",
"Abhijit",
""
],
[
"Biswas",
"Ritabrata",
""
]
] |
The thermodynamic properties of Cauchy horizon is a matter of interest. Event horizon and Cauchy horizon together can enlighten us about the micro-states of a black hole. In addition, if we consider a black hole metric modified with quantum terms, which is not forcing the geodesics to focus at a singularity, the study of horizons becomes much more interesting. The spacelike behavior inside the Cauchy horizon has a deep impact on the related thermodynamics. We analyze different thermodynamic product to check whether a right left string theory mode's addition type representation for the concerned thermodynamic parameters is possible or not. Stability of Cauchy horizon is studied.
|
2401.08783
|
Adri\'an Del R\'io Vega
|
Adri\'an del R\'io, Evelyn-Andreea Ester
|
Electrically charged black hole solutions in semiclassical gravity and
dynamics of linear perturbations
|
22 pages, one column format, 2 figures. Revised version: extra
references added, minor corrections, new appendix. Published in PRD
|
Phys. Rev. D 109, 105022 (2024)
|
10.1103/PhysRevD.109.105022
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We explore quantum corrections of electrically charged black holes subject to
vacuum polarization effects of fermion fields in QED. Solving this problem
exactly is challenging so we restrict to perturbative corrections that one can
obtain using the heat kernel expansion in the one-loop effective action for
electrons. Starting from the corrections originally computed by Drummond and
Hathrell, we solve the full semiclassical Einstein-Maxwell system of coupled
equations to leading order in Planck's constant, and find a new electrically
charged, static black hole solution. To probe these quantum corrections, we
study electromagnetic and gravitational (axial) perturbations on this
background, and derive the coupled system of Regge-Wheeler master equations
that govern the propagation of these waves. In the classical limit our results
agree with previous findings in the literature. We finally compare these
results with those that one can obtain by working out the Euler-Heisenberg
effective action. We find again a new electrically charged static black hole
spacetime, and derive the coupled system of Regge-Wheeler equations governing
the propagation of axial electromagnetic and gravitational perturbations.
Results are qualitatively similar in both cases. We briefly discuss some
challenges found in the numerical computation of the quasinormal mode frequency
spectra when quantum corrections are included.
|
[
{
"created": "Tue, 16 Jan 2024 19:04:42 GMT",
"version": "v1"
},
{
"created": "Sat, 18 May 2024 10:43:24 GMT",
"version": "v2"
}
] |
2024-05-21
|
[
[
"del Río",
"Adrián",
""
],
[
"Ester",
"Evelyn-Andreea",
""
]
] |
We explore quantum corrections of electrically charged black holes subject to vacuum polarization effects of fermion fields in QED. Solving this problem exactly is challenging so we restrict to perturbative corrections that one can obtain using the heat kernel expansion in the one-loop effective action for electrons. Starting from the corrections originally computed by Drummond and Hathrell, we solve the full semiclassical Einstein-Maxwell system of coupled equations to leading order in Planck's constant, and find a new electrically charged, static black hole solution. To probe these quantum corrections, we study electromagnetic and gravitational (axial) perturbations on this background, and derive the coupled system of Regge-Wheeler master equations that govern the propagation of these waves. In the classical limit our results agree with previous findings in the literature. We finally compare these results with those that one can obtain by working out the Euler-Heisenberg effective action. We find again a new electrically charged static black hole spacetime, and derive the coupled system of Regge-Wheeler equations governing the propagation of axial electromagnetic and gravitational perturbations. Results are qualitatively similar in both cases. We briefly discuss some challenges found in the numerical computation of the quasinormal mode frequency spectra when quantum corrections are included.
|
gr-qc/0202019
|
Vitor Cardoso
|
Vitor Cardoso, Jose' P. S. Lemos
|
Gravitational radiation from collisions at the speed of light: a
massless particle falling into a Schwarzschild black hole
|
10 pages, 3 figures, published version
|
Phys.Lett. B538 (2002) 1-5
|
10.1016/S0370-2693(02)01961-5
| null |
gr-qc astro-ph hep-ph hep-th
| null |
We compute spectra, waveforms, angular distribution and total gravitational
energy of the gravitiational radiation emitted during the radial infall of a
massless particle into a Schwarzschild black hole. Our fully relativistic
approach shows that (i) less than 50% of the total energy radiated to infinity
is carried by quadrupole waves, (ii) the spectra is flat, and (iii) the zero
frequency limit agrees extremely well with a prediction by Smarr. This process
may be looked at as the limiting case of collisions between massive particles
traveling at nearly the speed of light, by identifying the energy $E$ of the
massless particle with $m_0 \gamma$, $m_0$ being the mass of the test particle
and $\gamma$ the Lorentz boost parameter. We comment on the implications for
the two black hole collision at nearly the speed of light process, where we
obtain a 13.3% wave generation efficiency, and compare our results with
previous results by D'Eath and Payne.
|
[
{
"created": "Wed, 6 Feb 2002 14:26:23 GMT",
"version": "v1"
},
{
"created": "Sat, 15 Jun 2002 16:38:35 GMT",
"version": "v2"
}
] |
2015-06-25
|
[
[
"Cardoso",
"Vitor",
""
],
[
"Lemos",
"Jose' P. S.",
""
]
] |
We compute spectra, waveforms, angular distribution and total gravitational energy of the gravitiational radiation emitted during the radial infall of a massless particle into a Schwarzschild black hole. Our fully relativistic approach shows that (i) less than 50% of the total energy radiated to infinity is carried by quadrupole waves, (ii) the spectra is flat, and (iii) the zero frequency limit agrees extremely well with a prediction by Smarr. This process may be looked at as the limiting case of collisions between massive particles traveling at nearly the speed of light, by identifying the energy $E$ of the massless particle with $m_0 \gamma$, $m_0$ being the mass of the test particle and $\gamma$ the Lorentz boost parameter. We comment on the implications for the two black hole collision at nearly the speed of light process, where we obtain a 13.3% wave generation efficiency, and compare our results with previous results by D'Eath and Payne.
|
2112.08531
|
Karen Crowther
|
Karen Crowther and Sebastian De Haro
|
Four Attitudes Towards Singularities in the Search for a Theory of
Quantum Gravity
| null | null | null | null |
gr-qc physics.hist-ph
|
http://creativecommons.org/licenses/by/4.0/
|
Singularities in general relativity and quantum field theory are often taken
not only to motivate the search for a more-fundamental theory (quantum gravity,
QG), but also to characterise this new theory and shape expectations of what it
is to achieve. Here, we first evaluate how particular types of singularities
may suggest an incompleteness of current theories. We then classify four
different `attitudes' towards singularities in the search for QG, and show,
through examples in the physics literature, that these lead to different
scenarios for the new theory. Two of the attitudes prompt singularity
resolution, but only one suggests the need for a theory of QG. Rather than
evaluate the different attitudes, we close with some suggestions of factors
that influence the choice between them.
|
[
{
"created": "Wed, 15 Dec 2021 23:51:12 GMT",
"version": "v1"
}
] |
2021-12-17
|
[
[
"Crowther",
"Karen",
""
],
[
"De Haro",
"Sebastian",
""
]
] |
Singularities in general relativity and quantum field theory are often taken not only to motivate the search for a more-fundamental theory (quantum gravity, QG), but also to characterise this new theory and shape expectations of what it is to achieve. Here, we first evaluate how particular types of singularities may suggest an incompleteness of current theories. We then classify four different `attitudes' towards singularities in the search for QG, and show, through examples in the physics literature, that these lead to different scenarios for the new theory. Two of the attitudes prompt singularity resolution, but only one suggests the need for a theory of QG. Rather than evaluate the different attitudes, we close with some suggestions of factors that influence the choice between them.
|
2405.10813
|
Hajime Kobayashi
|
Chams Gharib Ali Barura, Hajime Kobayashi, Shinji Mukohyama, Naritaka
Oshita, Kazufumi Takahashi, Vicharit Yingcharoenrat
|
Tidal Love Numbers from EFT of Black Hole Perturbations with Timelike
Scalar Profile
|
40 pages
| null | null |
YITP-24-62, IPMU24-0018, RIKEN-iTHEMS-Report-24
|
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
We study static tidal Love numbers (TLNs) of a static and spherically
symmetric black hole for odd-parity metric perturbations. We describe black
hole perturbations using the effective field theory (EFT), formulated on an
arbitrary background with a timelike scalar profile in the context of
scalar-tensor theories. In particular, we obtain a static solution for the
generalized Regge-Wheeler equation order by order in a modified-gravity
parameter and extract the TLNs uniquely by analytic continuation of the
multipole index $\ell$ to non-integer values. For a stealth Schwarzschild black
hole, the TLNs are vanishing as in the case of Schwarzschild solution in
general relativity. We also study the case of Hayward black hole as an example
of non-stealth background, where we find that the TLNs are non-zero (or there
is a logarithmic running). This result suggests that our EFT allows for
non-vanishing TLNs and can in principle leave a detectable imprint on
gravitational waves from inspiralling binary systems, which opens a new window
for testing gravity in the strong-field regime.
|
[
{
"created": "Fri, 17 May 2024 14:27:26 GMT",
"version": "v1"
}
] |
2024-05-20
|
[
[
"Barura",
"Chams Gharib Ali",
""
],
[
"Kobayashi",
"Hajime",
""
],
[
"Mukohyama",
"Shinji",
""
],
[
"Oshita",
"Naritaka",
""
],
[
"Takahashi",
"Kazufumi",
""
],
[
"Yingcharoenrat",
"Vicharit",
""
]
] |
We study static tidal Love numbers (TLNs) of a static and spherically symmetric black hole for odd-parity metric perturbations. We describe black hole perturbations using the effective field theory (EFT), formulated on an arbitrary background with a timelike scalar profile in the context of scalar-tensor theories. In particular, we obtain a static solution for the generalized Regge-Wheeler equation order by order in a modified-gravity parameter and extract the TLNs uniquely by analytic continuation of the multipole index $\ell$ to non-integer values. For a stealth Schwarzschild black hole, the TLNs are vanishing as in the case of Schwarzschild solution in general relativity. We also study the case of Hayward black hole as an example of non-stealth background, where we find that the TLNs are non-zero (or there is a logarithmic running). This result suggests that our EFT allows for non-vanishing TLNs and can in principle leave a detectable imprint on gravitational waves from inspiralling binary systems, which opens a new window for testing gravity in the strong-field regime.
|
2106.03426
|
Olivier Minazzoli
|
Denis Arruga and Olivier Minazzoli
|
Analytical external spherical solutions in entangled relativity
|
11 pages, 10 figures. Few changes and additions in v2
| null |
10.1140/epjc/s10052-021-09818-x
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this manuscript, we present analytical external spherical solutions of
entangled relativity, which we compare to numerical solutions obtained in a
Tolman-Oppenheimer-Volkoff framework. Analytical and numerical solutions match
perfectly well outside spherical compact objects, therefore validating both
types of solutions at the same time. The analytical external (hairy) solutions
-- which depend on two parameters only -- may be used in order to easily
compute observables -- such as X-ray pusle profiles -- without having to rely
on an unknown equation of state for matter inside the compact object.
|
[
{
"created": "Mon, 7 Jun 2021 08:48:12 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Jun 2021 14:01:56 GMT",
"version": "v2"
}
] |
2021-12-08
|
[
[
"Arruga",
"Denis",
""
],
[
"Minazzoli",
"Olivier",
""
]
] |
In this manuscript, we present analytical external spherical solutions of entangled relativity, which we compare to numerical solutions obtained in a Tolman-Oppenheimer-Volkoff framework. Analytical and numerical solutions match perfectly well outside spherical compact objects, therefore validating both types of solutions at the same time. The analytical external (hairy) solutions -- which depend on two parameters only -- may be used in order to easily compute observables -- such as X-ray pusle profiles -- without having to rely on an unknown equation of state for matter inside the compact object.
|
2006.00634
|
Siddarth Ajith
|
Siddarth Ajith, Alexander Saffer, Kent Yagi
|
Rotating black holes in valid vector-tensor theories after GW170817
|
12 pages, 3 figures
|
Phys. Rev. D 102, 064031 (2020)
|
10.1103/PhysRevD.102.064031
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Vector-tensor theories beyond General Relativity have widely been studied in
the context of ultraviolet completion of gravity, endowing a mass to the
graviton and explaining dark energy phenomena. We here construct rotating black
hole solutions in vector-tensor theories valid after the binary neutron star
merger event GW170817 that placed very stringent bound on the propagation speed
of gravitational waves away from the speed of light. Such valid vector-tensor
theories are constructed by performing a generic conformal transformation to
Einstein-Maxwell theory, and the new rotating black hole solutions are
constructed by applying the same conformal transformation to the Kerr-Newman
solution. These theories fall outside of beyond generalized Proca theories but
are within an extended class of vector-tensor theories that satisfy a
degenerate condition to eliminate instability modes and are thus healthy. We
find that such conformal Kerr-Newman solutions preserve the location of the
singularities, event horizons and ergoregion boundary from Kerr-Newman, as well
as the multipole moments and the Petrov type. On the other hand, the
Hamilton-Jacobi equation is no longer separable, suggesting that the
Carter-like constant does not exist in this solution. The standard Newman-Janis
algorithm also does not work to construct the new solutions. We also compute
the epicyclic frequencies, the location of the innermost stable circular
orbits, and the Schwarzschild precession and apply the latter to the recent
GRAVITY measurement to place bounds on the deviations away from Kerr-Newman for
Sgr A$^*$.
|
[
{
"created": "Sun, 31 May 2020 23:07:02 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Sep 2020 17:00:23 GMT",
"version": "v2"
}
] |
2020-09-16
|
[
[
"Ajith",
"Siddarth",
""
],
[
"Saffer",
"Alexander",
""
],
[
"Yagi",
"Kent",
""
]
] |
Vector-tensor theories beyond General Relativity have widely been studied in the context of ultraviolet completion of gravity, endowing a mass to the graviton and explaining dark energy phenomena. We here construct rotating black hole solutions in vector-tensor theories valid after the binary neutron star merger event GW170817 that placed very stringent bound on the propagation speed of gravitational waves away from the speed of light. Such valid vector-tensor theories are constructed by performing a generic conformal transformation to Einstein-Maxwell theory, and the new rotating black hole solutions are constructed by applying the same conformal transformation to the Kerr-Newman solution. These theories fall outside of beyond generalized Proca theories but are within an extended class of vector-tensor theories that satisfy a degenerate condition to eliminate instability modes and are thus healthy. We find that such conformal Kerr-Newman solutions preserve the location of the singularities, event horizons and ergoregion boundary from Kerr-Newman, as well as the multipole moments and the Petrov type. On the other hand, the Hamilton-Jacobi equation is no longer separable, suggesting that the Carter-like constant does not exist in this solution. The standard Newman-Janis algorithm also does not work to construct the new solutions. We also compute the epicyclic frequencies, the location of the innermost stable circular orbits, and the Schwarzschild precession and apply the latter to the recent GRAVITY measurement to place bounds on the deviations away from Kerr-Newman for Sgr A$^*$.
|
2105.11139
|
Suvodip Mukherjee
|
Suvodip Mukherjee and Joseph Silk
|
Can we distinguish astrophysical from primordial black holes via the
stochastic gravitational wave background?
|
10 pages, 4 figures. Accepted for publication in MNRAS
| null |
10.1093/mnras/stab1932
| null |
gr-qc astro-ph.CO astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
One of the crucial windows for distinguishing astrophysical black holes from
primordial black holes is through the redshift evolution of their respective
merger rates. The low redshift population of black holes of astrophysical
origin is expected to follow the star formation rate. The corresponding peak in
their merger rate peaks at a redshift smaller than that of the star formation
rate peak ($z_p \approx 2$), depending on the time delay between the formation
and mergers of black holes. Black holes of primordial origin are going to be
present before the formation of the stars, and the merger rate of these sources
at high redshift is going to be large. We propose a joint estimation of a
hybrid merger rate from the stochastic gravitational wave background, which can
use the cosmic history of merger rates to distinguish between the two
populations of black holes. Using the latest bounds on the amplitude of the
stochastic gravitational wave background amplitude from the third observation
run of LIGO/Virgo, we obtain weak constraints at $68\%$ C.L. on the primordial
black hole merger rate index $2.56_{-1.76}^{+1.64}$ and astrophysical black
hole time delay $6.7_{-4.74}^{+4.22}$ Gyr. We should be able to distinguish
between the different populations of black holes with the forthcoming O5 and A+
detector sensitivities.
|
[
{
"created": "Mon, 24 May 2021 07:41:39 GMT",
"version": "v1"
},
{
"created": "Sun, 4 Jul 2021 06:17:08 GMT",
"version": "v2"
}
] |
2021-07-21
|
[
[
"Mukherjee",
"Suvodip",
""
],
[
"Silk",
"Joseph",
""
]
] |
One of the crucial windows for distinguishing astrophysical black holes from primordial black holes is through the redshift evolution of their respective merger rates. The low redshift population of black holes of astrophysical origin is expected to follow the star formation rate. The corresponding peak in their merger rate peaks at a redshift smaller than that of the star formation rate peak ($z_p \approx 2$), depending on the time delay between the formation and mergers of black holes. Black holes of primordial origin are going to be present before the formation of the stars, and the merger rate of these sources at high redshift is going to be large. We propose a joint estimation of a hybrid merger rate from the stochastic gravitational wave background, which can use the cosmic history of merger rates to distinguish between the two populations of black holes. Using the latest bounds on the amplitude of the stochastic gravitational wave background amplitude from the third observation run of LIGO/Virgo, we obtain weak constraints at $68\%$ C.L. on the primordial black hole merger rate index $2.56_{-1.76}^{+1.64}$ and astrophysical black hole time delay $6.7_{-4.74}^{+4.22}$ Gyr. We should be able to distinguish between the different populations of black holes with the forthcoming O5 and A+ detector sensitivities.
|
gr-qc/0110117
|
Reg Cahill
|
Reginald T. Cahill (Flinders University, Australia)
|
Process Physics: Inertia, Gravity and the Quantum
|
LaTex, 18 pages 1 eps file. Contribution to the 3rd Australasian
Conference on General Relativity and Gravitation, Perth, Australia, July 2001
|
Gen.Rel.Grav. 34 (2002) 1637-1656
| null | null |
gr-qc
| null |
Process Physics models reality as self-organising relational or semantic
information using a self-referentially limited neural network model. This
generalises the traditional non-process syntactical modelling of reality by
taking account of the limitations and characteristics of self-referential
syntactical information systems, discovered by Goedel and Chaitin, and the
analogies with the standard quantum formalism and its limitations. In process
physics space and quantum physics are emergent and unified, and time is a
distinct non-geometric process. Quantum phenomena are caused by fractal
topological defects embedded in and forming a growing three-dimensional fractal
process-space. Various features of the emergent physics are briefly discussed
including: quantum gravity, quantum field theory, limited causality and the
Born quantum measurement metarule, inertia, time-dilation effects, gravity and
the equivalence principle, a growing universe with a cosmological constant,
black holes and event horizons, and the emergence of classicality.
|
[
{
"created": "Mon, 29 Oct 2001 00:41:25 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Cahill",
"Reginald T.",
"",
"Flinders University, Australia"
]
] |
Process Physics models reality as self-organising relational or semantic information using a self-referentially limited neural network model. This generalises the traditional non-process syntactical modelling of reality by taking account of the limitations and characteristics of self-referential syntactical information systems, discovered by Goedel and Chaitin, and the analogies with the standard quantum formalism and its limitations. In process physics space and quantum physics are emergent and unified, and time is a distinct non-geometric process. Quantum phenomena are caused by fractal topological defects embedded in and forming a growing three-dimensional fractal process-space. Various features of the emergent physics are briefly discussed including: quantum gravity, quantum field theory, limited causality and the Born quantum measurement metarule, inertia, time-dilation effects, gravity and the equivalence principle, a growing universe with a cosmological constant, black holes and event horizons, and the emergence of classicality.
|
gr-qc/0212064
|
David P. Rideout
|
David Rideout
|
Dynamics of Causal Sets
|
121 pages, 32 figures, Ph.D. thesis, LaTeX
| null | null |
SU-GP-01/4-2
|
gr-qc
| null |
The Causal Set approach to quantum gravity asserts that spacetime, at its
smallest length scale, has a discrete structure. This discrete structure takes
the form of a locally finite order relation, where the order, corresponding
with the macroscopic notion of spacetime causality, is taken to be a
fundamental aspect of nature.
After an introduction to the Causal Set approach, this thesis considers a
simple toy dynamics for causal sets. Numerical simulations of the model provide
evidence for the existence of a continuum limit. While studying this toy
dynamics, a picture arises of how the dynamics can be generalized in such a way
that the theory could hope to produce more physically realistic causal sets. By
thinking in terms of a stochastic growth process, and positing some fundamental
principles, we are led almost uniquely to a family of dynamical laws
(stochastic processes) parameterized by a countable sequence of coupling
constants. This result is quite promising in that we now know how to speak of
dynamics for a theory with discrete time. In addition, these dynamics can be
expressed in terms of state models of Ising spins living on the relations of
the causal set, which indicates how non-gravitational matter may arise from the
theory without having to be built in at the fundamental level.
These results are encouraging in that there exists a natural way to transform
this classical theory, which is expressed in terms of a probability measure, to
a quantum theory, expressed in terms of a quantum measure. A sketch as to how
one might proceed in doing this is provided. Thus there is good reason to
expect that Causal Sets are close to providing a background independent theory
of quantum gravity.
|
[
{
"created": "Sat, 14 Dec 2002 02:29:54 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Rideout",
"David",
""
]
] |
The Causal Set approach to quantum gravity asserts that spacetime, at its smallest length scale, has a discrete structure. This discrete structure takes the form of a locally finite order relation, where the order, corresponding with the macroscopic notion of spacetime causality, is taken to be a fundamental aspect of nature. After an introduction to the Causal Set approach, this thesis considers a simple toy dynamics for causal sets. Numerical simulations of the model provide evidence for the existence of a continuum limit. While studying this toy dynamics, a picture arises of how the dynamics can be generalized in such a way that the theory could hope to produce more physically realistic causal sets. By thinking in terms of a stochastic growth process, and positing some fundamental principles, we are led almost uniquely to a family of dynamical laws (stochastic processes) parameterized by a countable sequence of coupling constants. This result is quite promising in that we now know how to speak of dynamics for a theory with discrete time. In addition, these dynamics can be expressed in terms of state models of Ising spins living on the relations of the causal set, which indicates how non-gravitational matter may arise from the theory without having to be built in at the fundamental level. These results are encouraging in that there exists a natural way to transform this classical theory, which is expressed in terms of a probability measure, to a quantum theory, expressed in terms of a quantum measure. A sketch as to how one might proceed in doing this is provided. Thus there is good reason to expect that Causal Sets are close to providing a background independent theory of quantum gravity.
|
gr-qc/9809020
|
James M. Nester
|
C. M. Chen (Moscow State U.), J. M. Nester (Nat. Central U.)
|
Quasilocal quantities for GR and other gravity theories
|
LaTeX (ioplppt.sty), 33 pages, no figures, accepted by CQG, small
improvements, clarifications and new references, especially connection to
recent work of Katz et al
|
Class.Quant.Grav.16:1279-1304,1999
|
10.1088/0264-9381/16/4/018
| null |
gr-qc
| null |
From a covariant Hamiltonian formulation, by using symplectic ideas, we
obtain certain covariant boundary expressions for the quasilocal quantities of
general relativity and other geometric gravity theories. The contribution from
each of the independent dynamic geometric variables (the frame, metric or
connection) has two possible covariant forms associated with the selected type
of boundary condition. The quasilocal expressions also depend on a reference
value for each dynamic variable and a displacement vector field. Integrating
over a closed two surface with suitable choices for the vector field gives the
quasilocal energy, momentum and angular momentum. For the special cases of
Einstein's theory and the Poincar\'e Gauge theory our expressions are similar
to some previously known expressions and give good values for the total ADM and
Bondi quantities. We apply our formalism to black hole thermodynamics obtaining
the first law and an associated entropy expression for these general gravity
theories. For Einstein's theory our quasilocal expressions are evaluated on
static spherically symmetric solutions and compared with the findings of some
other researchers. The choices needed for the formalism to associate a
quasilocal expression with the boundary of a region are discussed.
|
[
{
"created": "Fri, 4 Sep 1998 06:32:48 GMT",
"version": "v1"
},
{
"created": "Sun, 14 Feb 1999 06:04:57 GMT",
"version": "v2"
}
] |
2014-11-17
|
[
[
"Chen",
"C. M.",
"",
"Moscow State U."
],
[
"Nester",
"J. M.",
"",
"Nat. Central U."
]
] |
From a covariant Hamiltonian formulation, by using symplectic ideas, we obtain certain covariant boundary expressions for the quasilocal quantities of general relativity and other geometric gravity theories. The contribution from each of the independent dynamic geometric variables (the frame, metric or connection) has two possible covariant forms associated with the selected type of boundary condition. The quasilocal expressions also depend on a reference value for each dynamic variable and a displacement vector field. Integrating over a closed two surface with suitable choices for the vector field gives the quasilocal energy, momentum and angular momentum. For the special cases of Einstein's theory and the Poincar\'e Gauge theory our expressions are similar to some previously known expressions and give good values for the total ADM and Bondi quantities. We apply our formalism to black hole thermodynamics obtaining the first law and an associated entropy expression for these general gravity theories. For Einstein's theory our quasilocal expressions are evaluated on static spherically symmetric solutions and compared with the findings of some other researchers. The choices needed for the formalism to associate a quasilocal expression with the boundary of a region are discussed.
|
2405.18893
|
Aleksandar Mikovic
|
Aleksandar Mikovic
|
Physical States and Transition Amplitudes in Piecewise Flat Quantum
Gravity
|
23 pages, 7 figures, expanded version accepted for publication in
Int. J. Mod. Phys. D
| null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
We show how the path integral for gravity and matter on a piecewise flat
spacetime can be used to define the physical quantum gravity states and the
related transition amplitudes. The physical states are given by the path
integrals for open manifolds from a certain topological class, while the
corresponding transition amplitudes are obtained by gluing two such open
manifolds into a closed one and calculating the corresponding path integral. We
also solve the problem of how to associate a quantum gravity state to an
effective action. This is done by using the path integral for a closed manifold
from the transition-amplitude topological class so that the state which
corresponds to the effective action can be choosen to be the Hartle-Hawking or
the Vilenkin wavefunction for the vacuum manifold component of the
transition-amplitude manifold.
|
[
{
"created": "Wed, 29 May 2024 08:53:10 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Aug 2024 10:36:21 GMT",
"version": "v2"
}
] |
2024-08-08
|
[
[
"Mikovic",
"Aleksandar",
""
]
] |
We show how the path integral for gravity and matter on a piecewise flat spacetime can be used to define the physical quantum gravity states and the related transition amplitudes. The physical states are given by the path integrals for open manifolds from a certain topological class, while the corresponding transition amplitudes are obtained by gluing two such open manifolds into a closed one and calculating the corresponding path integral. We also solve the problem of how to associate a quantum gravity state to an effective action. This is done by using the path integral for a closed manifold from the transition-amplitude topological class so that the state which corresponds to the effective action can be choosen to be the Hartle-Hawking or the Vilenkin wavefunction for the vacuum manifold component of the transition-amplitude manifold.
|
gr-qc/9506050
|
David Wands
|
Juan Garcia-Bellido and David Wands
|
Constraints from Inflation on Scalar-Tensor Gravity Theories
|
LaTeX (with RevTex) 19 pages, 8 uuencoded figures appended, also
available on WWW via http://star.maps.susx.ac.uk/index.html
|
Phys. Rev. D 52, 6739 (1995)
|
10.1103/PhysRevD.52.6739
|
SUSSEX-AST-95/6-3, IEM-FT-107/95
|
gr-qc astro-ph
| null |
We show how observations of the perturbation spectra produced during
inflation may be used to constrain the parameters of general scalar-tensor
theories of gravity, which include both an inflaton and dilaton field. An
interesting feature of these models is the possibility that the curvature
perturbations on super-horizon scales may not be constant due to non-adiabatic
perturbations of the two fields. Within a given model, the tilt and relative
amplitude of the scalar and tensor perturbation spectra gives constraints on
the parameters of the gravity theory, which may be comparable with those from
primordial nucleosynthesis and post-Newtonian experiments.
|
[
{
"created": "Fri, 23 Jun 1995 14:20:21 GMT",
"version": "v1"
}
] |
2016-08-24
|
[
[
"Garcia-Bellido",
"Juan",
""
],
[
"Wands",
"David",
""
]
] |
We show how observations of the perturbation spectra produced during inflation may be used to constrain the parameters of general scalar-tensor theories of gravity, which include both an inflaton and dilaton field. An interesting feature of these models is the possibility that the curvature perturbations on super-horizon scales may not be constant due to non-adiabatic perturbations of the two fields. Within a given model, the tilt and relative amplitude of the scalar and tensor perturbation spectra gives constraints on the parameters of the gravity theory, which may be comparable with those from primordial nucleosynthesis and post-Newtonian experiments.
|
2108.03075
|
Andrew Finch
|
Salvatore Capozziello, Andrew Finch, Jackson Levi Said, Alessio Magro
|
The $3+1$ Formalism in the Geometric Trinity of Gravity
|
23 pages
| null |
10.1140/epjc/s10052-021-09944-6
| null |
gr-qc astro-ph.CO
|
http://creativecommons.org/licenses/by/4.0/
|
The geometric trinity of gravity offers a platform in which gravity can be
formulated in three analogous approaches, namely curvature, torsion and
nonmetricity. In this vein, general relativity can be expressed in three
dynamically equivalent ways which may offer insights into the different
properties of these decompositions such as their Hamiltonian structure, the
efficiency of numerical analyses, as well as the classification of
gravitational field degrees of freedom. In this work, we take a $3+1$
decomposition of the teleparallel equivalent of general relativity and the
symmetric teleparallel equivalent of general relativity which are both
dynamically equivalent to curvature based general relativity. By splitting the
spacetime metric and corresponding tetrad into their spatial and temporal parts
as well as through finding the Gauss-like equations, it is possible to set up a
general foundation for the different formulations of gravity. Based on these
results, general $3$-tetrad and $3$-metric evolution equations are derived.
Finally through the choice of the two respective connections, the metric $3+1$
formulation for general relativity is recovered as well as the tetrad $3+1$
formulation of the teleparallel equivalent of general relativity and the metric
$3+1$ formulation of symmetric teleparallel equivalent of general relativity.
The approach is capable, in principle, of resolving common features of the
various formulations of general relativity at a fundamental level and pointing
out characteristics that extensions and alternatives to the various
formulations can present.
|
[
{
"created": "Fri, 6 Aug 2021 12:17:01 GMT",
"version": "v1"
}
] |
2022-10-12
|
[
[
"Capozziello",
"Salvatore",
""
],
[
"Finch",
"Andrew",
""
],
[
"Said",
"Jackson Levi",
""
],
[
"Magro",
"Alessio",
""
]
] |
The geometric trinity of gravity offers a platform in which gravity can be formulated in three analogous approaches, namely curvature, torsion and nonmetricity. In this vein, general relativity can be expressed in three dynamically equivalent ways which may offer insights into the different properties of these decompositions such as their Hamiltonian structure, the efficiency of numerical analyses, as well as the classification of gravitational field degrees of freedom. In this work, we take a $3+1$ decomposition of the teleparallel equivalent of general relativity and the symmetric teleparallel equivalent of general relativity which are both dynamically equivalent to curvature based general relativity. By splitting the spacetime metric and corresponding tetrad into their spatial and temporal parts as well as through finding the Gauss-like equations, it is possible to set up a general foundation for the different formulations of gravity. Based on these results, general $3$-tetrad and $3$-metric evolution equations are derived. Finally through the choice of the two respective connections, the metric $3+1$ formulation for general relativity is recovered as well as the tetrad $3+1$ formulation of the teleparallel equivalent of general relativity and the metric $3+1$ formulation of symmetric teleparallel equivalent of general relativity. The approach is capable, in principle, of resolving common features of the various formulations of general relativity at a fundamental level and pointing out characteristics that extensions and alternatives to the various formulations can present.
|
1411.0270
|
Bang-Yen Chen
|
Bang-Yen Chen
|
A simple characterization of generalized Robertson-Walker spacetimes
|
5 pages, to appear in General Relativity and Gravitation
| null |
10.1007/s10714-014-1833-9
| null |
gr-qc math.DG
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A generalized Robertson-Walker spacetime is the warped product with base an
open interval of the real line endowed with the opposite of its metric and base
any Riemannian manifold. The family of generalized Robertson-Walker spacetimes
widely extends the one of classical Robertson-Walker spacetimes. In this
article we prove a very simple characterization of generalized Robertson-Walker
spacetimes; namely, a Lorentzian manifold is a generalized Robertson-Walker
spacetime if and only if it admits a timelike concircular vector field.
|
[
{
"created": "Sun, 2 Nov 2014 15:29:52 GMT",
"version": "v1"
}
] |
2015-06-23
|
[
[
"Chen",
"Bang-Yen",
""
]
] |
A generalized Robertson-Walker spacetime is the warped product with base an open interval of the real line endowed with the opposite of its metric and base any Riemannian manifold. The family of generalized Robertson-Walker spacetimes widely extends the one of classical Robertson-Walker spacetimes. In this article we prove a very simple characterization of generalized Robertson-Walker spacetimes; namely, a Lorentzian manifold is a generalized Robertson-Walker spacetime if and only if it admits a timelike concircular vector field.
|
1302.0800
|
Jeffrey Winicour
|
H-O. Kreiss, J. Winicour
|
Geometric Boundary Data for the Gravitational Field
|
Clarification given and typos corrected. Published version
|
Class. Quantum Grav. 31 (2014) 065004
|
10.1088/0264-9381/31/6/065004
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
An outstanding issue in the treatment of boundaries in general relativity is
the lack of a local geometric interpretation of the necessary boundary data.
For the Cauchy problem, the initial data is supplied by the 3-metric and
extrinsic curvature of the initial Cauchy hypersurface.. This Cauchy data
determines a solution to Einstein's equations which is unique up to a
diffeomorphism. Here, we show how three pieces of boundary data, which are
associated locally with the geometry of the boundary, likewise determine a
solution of the initial-boundary value problem which is unique up to a
diffeomorphism. One piece of this data, constructed from the extrinsic
curvature of the boundary, determines the dynamical evolution of the boundary.
The other two pieces constitute a conformal class of rank-2, positive definite
metrics, which represent the two gravitational degrees of freedom.
|
[
{
"created": "Mon, 4 Feb 2013 19:03:11 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Jun 2013 17:09:31 GMT",
"version": "v2"
},
{
"created": "Tue, 25 Feb 2014 14:38:11 GMT",
"version": "v3"
}
] |
2014-03-05
|
[
[
"Kreiss",
"H-O.",
""
],
[
"Winicour",
"J.",
""
]
] |
An outstanding issue in the treatment of boundaries in general relativity is the lack of a local geometric interpretation of the necessary boundary data. For the Cauchy problem, the initial data is supplied by the 3-metric and extrinsic curvature of the initial Cauchy hypersurface.. This Cauchy data determines a solution to Einstein's equations which is unique up to a diffeomorphism. Here, we show how three pieces of boundary data, which are associated locally with the geometry of the boundary, likewise determine a solution of the initial-boundary value problem which is unique up to a diffeomorphism. One piece of this data, constructed from the extrinsic curvature of the boundary, determines the dynamical evolution of the boundary. The other two pieces constitute a conformal class of rank-2, positive definite metrics, which represent the two gravitational degrees of freedom.
|
2405.08170
|
Maciej Dunajski
|
Maciej Dunajski, Paul Tod
|
Twistor theory of the Chen--Teo gravitational instanton
|
Dedicated to Nick Woodhouse on the occasion of his 75th birthday. The
link between the twistor mass and NUT parameters and the Kunduri-Lucietti
mass and the Chen-Teo NUT clarified following a comment from James Lucietti
| null | null | null |
gr-qc hep-th math.DG
|
http://creativecommons.org/publicdomain/zero/1.0/
|
Toric Ricci--flat metrics in dimension four correspond to certain holomorphic
vector bundles over a twistor space. We construct these bundles explicitly, by
exhibiting and characterising their patching matrices, for the five--parameter
family of Riemannian ALF metrics constructed by Chen and Teo. The Chen--Teo
family contains a two--parameter family of asymptotically flat gravitational
instantons. The patching matrices for these instantons take a simple rational
form.
|
[
{
"created": "Mon, 13 May 2024 20:29:50 GMT",
"version": "v1"
},
{
"created": "Wed, 29 May 2024 21:17:01 GMT",
"version": "v2"
}
] |
2024-05-31
|
[
[
"Dunajski",
"Maciej",
""
],
[
"Tod",
"Paul",
""
]
] |
Toric Ricci--flat metrics in dimension four correspond to certain holomorphic vector bundles over a twistor space. We construct these bundles explicitly, by exhibiting and characterising their patching matrices, for the five--parameter family of Riemannian ALF metrics constructed by Chen and Teo. The Chen--Teo family contains a two--parameter family of asymptotically flat gravitational instantons. The patching matrices for these instantons take a simple rational form.
|
1110.1668
|
Jeffrey Kaplan
|
Michael I. Cohen, Jeffrey D. Kaplan, and Mark A. Scheel
|
On Toroidal Horizons in Binary Black Hole Inspirals
|
Submitted to Phys. Rev. D
|
Phys. Rev. D 85, 024031 (2012)
|
10.1103/PhysRevD.85.024031
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We examine the structure of the event horizon for numerical simulations of
two black holes that begin in a quasicircular orbit, inspiral, and finally
merge. We find that the spatial cross section of the merged event horizon has
spherical topology (to the limit of our resolution), despite the expectation
that generic binary black hole mergers in the absence of symmetries should
result in an event horizon that briefly has a toroidal cross section. Using
insight gained from our numerical simulations, we investigate how the choice of
time slicing affects both the spatial cross section of the event horizon and
the locus of points at which generators of the event horizon cross. To ensure
the robustness of our conclusions, our results are checked at multiple
numerical resolutions. 3D visualization data for these resolutions are
available for public access online. We find that the structure of the horizon
generators in our simulations is consistent with expectations, and the lack of
toroidal horizons in our simulations is due to our choice of time slicing.
|
[
{
"created": "Fri, 7 Oct 2011 22:00:55 GMT",
"version": "v1"
}
] |
2012-12-04
|
[
[
"Cohen",
"Michael I.",
""
],
[
"Kaplan",
"Jeffrey D.",
""
],
[
"Scheel",
"Mark A.",
""
]
] |
We examine the structure of the event horizon for numerical simulations of two black holes that begin in a quasicircular orbit, inspiral, and finally merge. We find that the spatial cross section of the merged event horizon has spherical topology (to the limit of our resolution), despite the expectation that generic binary black hole mergers in the absence of symmetries should result in an event horizon that briefly has a toroidal cross section. Using insight gained from our numerical simulations, we investigate how the choice of time slicing affects both the spatial cross section of the event horizon and the locus of points at which generators of the event horizon cross. To ensure the robustness of our conclusions, our results are checked at multiple numerical resolutions. 3D visualization data for these resolutions are available for public access online. We find that the structure of the horizon generators in our simulations is consistent with expectations, and the lack of toroidal horizons in our simulations is due to our choice of time slicing.
|
1612.08525
|
Sunil Maharaj
|
P. Mafa Takisa, S. D. Maharaj
|
Anisotropic charged core envelope star
|
11 pages, submitted for publication
|
Astrophys. Space Sci. 361, 262 (2016)
|
10.1007/s10509-016-2840-y
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study a charged compact object with anisotropic pressures in a core
envelope setting. The equation of state is quadratic in the core and linear in
the envelope. There is smooth matching between the three regions: the core,
envelope and the Reissner-Nordstr\"{o}m exterior. We show that the presence of
the electric field affects the masses, radii and compactification factors of
stellar objects with values which are in agreement with previous studies. We
investigate in particular the effect of electric field on the physical features
of the pulsar PSR J1614-2230 in the core envelope model. The gravitational
potentials and the matter variables are well behaved within the stellar object.
We demonstrate that the radius of the core and the envelope can vary by
changing the parameters in the speed of sound.
|
[
{
"created": "Tue, 27 Dec 2016 07:57:33 GMT",
"version": "v1"
}
] |
2017-01-04
|
[
[
"Takisa",
"P. Mafa",
""
],
[
"Maharaj",
"S. D.",
""
]
] |
We study a charged compact object with anisotropic pressures in a core envelope setting. The equation of state is quadratic in the core and linear in the envelope. There is smooth matching between the three regions: the core, envelope and the Reissner-Nordstr\"{o}m exterior. We show that the presence of the electric field affects the masses, radii and compactification factors of stellar objects with values which are in agreement with previous studies. We investigate in particular the effect of electric field on the physical features of the pulsar PSR J1614-2230 in the core envelope model. The gravitational potentials and the matter variables are well behaved within the stellar object. We demonstrate that the radius of the core and the envelope can vary by changing the parameters in the speed of sound.
|
gr-qc/9902074
|
Daniel Grumiller
|
D. Grumiller, W. Kummer
|
Absolute conservation law for black holes
|
LaTex, 17 pages, final version, to appear in Phys. Rev. D
|
Phys.Rev.D61:064006,2000
|
10.1103/PhysRevD.61.064006
|
TUW-99-02, Vers. 2.1
|
gr-qc
| null |
In all 2d theories of gravity a conservation law connects the (space-time
dependent) mass aspect function at all times and all radii with an integral of
the matter fields. It depends on an arbitrary constant which may be interpreted
as determining the initial value together with the initial values for the
matter field. We discuss this for spherically reduced Einstein-gravity in a
diagonal metric and in a Bondi-Sachs metric using the first order formulation
of spherically reduced gravity, which allows easy and direct fixations of any
type of gauge. The relation of our conserved quantity to the ADM and Bondi mass
is investigated. Further possible applications (ideal fluid, black holes in
higher dimensions or AdS spacetimes etc.) are straightforward generalizations.
|
[
{
"created": "Tue, 23 Feb 1999 15:35:32 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Feb 1999 10:03:37 GMT",
"version": "v2"
},
{
"created": "Thu, 24 Jun 1999 14:20:35 GMT",
"version": "v3"
},
{
"created": "Mon, 8 Nov 1999 13:31:42 GMT",
"version": "v4"
}
] |
2014-11-17
|
[
[
"Grumiller",
"D.",
""
],
[
"Kummer",
"W.",
""
]
] |
In all 2d theories of gravity a conservation law connects the (space-time dependent) mass aspect function at all times and all radii with an integral of the matter fields. It depends on an arbitrary constant which may be interpreted as determining the initial value together with the initial values for the matter field. We discuss this for spherically reduced Einstein-gravity in a diagonal metric and in a Bondi-Sachs metric using the first order formulation of spherically reduced gravity, which allows easy and direct fixations of any type of gauge. The relation of our conserved quantity to the ADM and Bondi mass is investigated. Further possible applications (ideal fluid, black holes in higher dimensions or AdS spacetimes etc.) are straightforward generalizations.
|
gr-qc/0209089
|
Luc Blanchet
|
Luc Blanchet and Bala Iyer
|
Third post-Newtonian dynamics of compact binaries: Equations of motion
in the center-of-mass frame
|
31 pages, to appear in Classical and Quantum Gravity
|
Class.Quant.Grav. 20 (2003) 755
|
10.1088/0264-9381/20/4/309
| null |
gr-qc
| null |
The equations of motion of compact binary systems and their associated
Lagrangian formulation have been derived in previous works at the third
post-Newtonian (3PN) approximation of general relativity in harmonic
coordinates. In the present work we investigate the binary's relative dynamics
in the center-of-mass frame (center of mass located at the origin of the
coordinates). We obtain the 3PN-accurate expressions of the center-of-mass
positions and equations of the relative binary motion. We show that the
equations derive from a Lagrangian (neglecting the radiation reaction), from
which we deduce the conserved center-of-mass energy and angular momentum at the
3PN order. The harmonic-coordinates center-of-mass Lagrangian is equivalent,
{\it via} a contact transformation of the particles' variables, to the
center-of-mass Hamiltonian in ADM coordinates that is known from the
post-Newtonian ADM-Hamiltonian formalism. As an application we investigate the
dynamical stability of circular binary orbits at the 3PN order.
|
[
{
"created": "Tue, 24 Sep 2002 14:16:31 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Jan 2003 11:15:00 GMT",
"version": "v2"
}
] |
2017-08-23
|
[
[
"Blanchet",
"Luc",
""
],
[
"Iyer",
"Bala",
""
]
] |
The equations of motion of compact binary systems and their associated Lagrangian formulation have been derived in previous works at the third post-Newtonian (3PN) approximation of general relativity in harmonic coordinates. In the present work we investigate the binary's relative dynamics in the center-of-mass frame (center of mass located at the origin of the coordinates). We obtain the 3PN-accurate expressions of the center-of-mass positions and equations of the relative binary motion. We show that the equations derive from a Lagrangian (neglecting the radiation reaction), from which we deduce the conserved center-of-mass energy and angular momentum at the 3PN order. The harmonic-coordinates center-of-mass Lagrangian is equivalent, {\it via} a contact transformation of the particles' variables, to the center-of-mass Hamiltonian in ADM coordinates that is known from the post-Newtonian ADM-Hamiltonian formalism. As an application we investigate the dynamical stability of circular binary orbits at the 3PN order.
|
2404.08740
|
Marco Brito MSc
|
Marco Brito, Carlos Herdeiro, Nicolas Sanchis-Gual, Etevaldo dos
Santos Costa Filho, Miguel Zilh\~ao
|
Self-interactions can (also) destabilize bosonic stars
|
14 pages, 11 figures
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the dynamical stability of Proca-Higgs stars, in spherical symmetry.
These are solutions of the Einstein-Proca-Higgs model, which features a
Higgs-like field coupled to a Proca field, both of which minimally coupled to
the gravitational field. The corresponding stars can be regarded as Proca stars
with self-interactions, while avoiding the hyperbolicity issues of
self-interacting Einstein-Proca models. We report that these configurations are
stable near the Proca limit in the candidate stable branches, but exhibit
instabilities in certain parts of the parameter space, even in the candidate
stable branches, regaining their stability for very strong self-interactions.
This shows that for these models, unlike various examples of scalar boson
stars, self-interactions can deteriorate, rather than improve, the dynamical
robustness of bosonic stars.
|
[
{
"created": "Fri, 12 Apr 2024 18:04:23 GMT",
"version": "v1"
}
] |
2024-04-16
|
[
[
"Brito",
"Marco",
""
],
[
"Herdeiro",
"Carlos",
""
],
[
"Sanchis-Gual",
"Nicolas",
""
],
[
"Filho",
"Etevaldo dos Santos Costa",
""
],
[
"Zilhão",
"Miguel",
""
]
] |
We study the dynamical stability of Proca-Higgs stars, in spherical symmetry. These are solutions of the Einstein-Proca-Higgs model, which features a Higgs-like field coupled to a Proca field, both of which minimally coupled to the gravitational field. The corresponding stars can be regarded as Proca stars with self-interactions, while avoiding the hyperbolicity issues of self-interacting Einstein-Proca models. We report that these configurations are stable near the Proca limit in the candidate stable branches, but exhibit instabilities in certain parts of the parameter space, even in the candidate stable branches, regaining their stability for very strong self-interactions. This shows that for these models, unlike various examples of scalar boson stars, self-interactions can deteriorate, rather than improve, the dynamical robustness of bosonic stars.
|
1302.2919
|
Michael Boyle
|
Michael Boyle
|
Angular velocity of gravitational radiation from precessing binaries and
the corotating frame
|
Accepted by PRD; added a few clarifications
|
Phys. Rev. D 87, 104006 (2013)
|
10.1103/PhysRevD.87.104006
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This paper defines an angular velocity for time-dependent functions on the
sphere, and applies it to gravitational waveforms from compact binaries.
Because it is geometrically meaningful and has a clear physical motivation, the
angular velocity is uniquely useful in helping to solve an important---and
largely ignored---problem in models of compact binaries: the inverse problem of
deducing the physical parameters of a system from the gravitational waves
alone. It is also used to define the corotating frame of the waveform. When
decomposed in this frame, the waveform has no rotational dynamics and is
therefore as slowly evolving as possible. The resulting simplifications lead to
straightforward methods for accurately comparing waveforms and constructing
hybrids. As formulated in this paper, the methods can be applied robustly to
both precessing and nonprecessing waveforms, providing a clear, comprehensive,
and consistent framework for waveform analysis. Explicit implementations of all
these methods are provided in accompanying computer code.
|
[
{
"created": "Tue, 12 Feb 2013 21:00:03 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Feb 2013 20:42:47 GMT",
"version": "v2"
},
{
"created": "Wed, 10 Apr 2013 03:22:31 GMT",
"version": "v3"
}
] |
2017-10-27
|
[
[
"Boyle",
"Michael",
""
]
] |
This paper defines an angular velocity for time-dependent functions on the sphere, and applies it to gravitational waveforms from compact binaries. Because it is geometrically meaningful and has a clear physical motivation, the angular velocity is uniquely useful in helping to solve an important---and largely ignored---problem in models of compact binaries: the inverse problem of deducing the physical parameters of a system from the gravitational waves alone. It is also used to define the corotating frame of the waveform. When decomposed in this frame, the waveform has no rotational dynamics and is therefore as slowly evolving as possible. The resulting simplifications lead to straightforward methods for accurately comparing waveforms and constructing hybrids. As formulated in this paper, the methods can be applied robustly to both precessing and nonprecessing waveforms, providing a clear, comprehensive, and consistent framework for waveform analysis. Explicit implementations of all these methods are provided in accompanying computer code.
|
1308.6489
|
Anja Marunovic
|
Anja Marunovic and Miljenko Murkovic
|
A novel black hole mimicker: a boson star and a global monopole
nonminimally coupled to gravity
|
22 pages, 18 figures; References added; matches published version
|
Class. Quantum Grav. 31 (2014) 045010
|
10.1088/0264-9381/31/4/045010
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A field-theoretic model for a highly compact object that mimicks a black hole
is found for the gravitationally interacting system of a boson star and a
global monopole which are nonminimally coupled to gravity. According to the
strength of the nonlinear gravitational effects and the gravitational
backreaction, three distinct coupling regimes are featured: weak, mild and
strong. In the strong coupling regime we show that a repulsive monopole
stabilizes an attractive boson star and the resulting configuration exhibits
large energy density, large (and negative) principal pressures, large
compactness, large effective potential, large local forces, and yet exhibits no
event horizon. As such a composite system of a boson star and a global monopole
represents a convincing microscopic candidate for a black hole mimicker.
|
[
{
"created": "Thu, 29 Aug 2013 14:58:33 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Feb 2014 16:45:46 GMT",
"version": "v2"
}
] |
2014-02-12
|
[
[
"Marunovic",
"Anja",
""
],
[
"Murkovic",
"Miljenko",
""
]
] |
A field-theoretic model for a highly compact object that mimicks a black hole is found for the gravitationally interacting system of a boson star and a global monopole which are nonminimally coupled to gravity. According to the strength of the nonlinear gravitational effects and the gravitational backreaction, three distinct coupling regimes are featured: weak, mild and strong. In the strong coupling regime we show that a repulsive monopole stabilizes an attractive boson star and the resulting configuration exhibits large energy density, large (and negative) principal pressures, large compactness, large effective potential, large local forces, and yet exhibits no event horizon. As such a composite system of a boson star and a global monopole represents a convincing microscopic candidate for a black hole mimicker.
|
2405.01201
|
Thomas Thiemann
|
Thomas Thiemann
|
Observations on representations of the spatial diffeomorphism group and
algebra in all dimensions
| null | null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The canonical quantisation of General Relativity including matter on a
spacetime manifold in the globally hyperbolic setting involves in particular
the representation theory of the spatial diffeomorphism group (SDG), and/or its
Lie algebra (SDA), of the underlying spatial submanifold. There are well known
Fock representations of the SDA in one spatial dimension and non-Fock
representations of the SDG in all dimensions. The latter are not strongly
continuous and do not descend to representations of the SDA.
In this work we report some partial results on non anomalous representations
of the SDA for both geometry and matter: 1. Background independent Fock
representations of the SDA by operators exist in all dimensions. 2. Infinitely
many unitary equivalence classes of background dependent Fock representations
of the SDA by operators exist in one dimension but these do not extend to
higher dimensions. 3. Infinitely many unitary equivalence classes of background
dependent Fock representations of the SDA of volume preserving diffeomorphisms
by operators exist in all dimensions. 4. Infinitely many unitary equivalence
classes of background dependent Fock representations of the SDA by quadratic
forms exist in all dimensions.
Except for 1. these representations do not descend from an invariant state of
the Weyl algebra and 4. points to a new strategy for solving the quantum
constraints.
|
[
{
"created": "Thu, 2 May 2024 11:43:14 GMT",
"version": "v1"
}
] |
2024-05-03
|
[
[
"Thiemann",
"Thomas",
""
]
] |
The canonical quantisation of General Relativity including matter on a spacetime manifold in the globally hyperbolic setting involves in particular the representation theory of the spatial diffeomorphism group (SDG), and/or its Lie algebra (SDA), of the underlying spatial submanifold. There are well known Fock representations of the SDA in one spatial dimension and non-Fock representations of the SDG in all dimensions. The latter are not strongly continuous and do not descend to representations of the SDA. In this work we report some partial results on non anomalous representations of the SDA for both geometry and matter: 1. Background independent Fock representations of the SDA by operators exist in all dimensions. 2. Infinitely many unitary equivalence classes of background dependent Fock representations of the SDA by operators exist in one dimension but these do not extend to higher dimensions. 3. Infinitely many unitary equivalence classes of background dependent Fock representations of the SDA of volume preserving diffeomorphisms by operators exist in all dimensions. 4. Infinitely many unitary equivalence classes of background dependent Fock representations of the SDA by quadratic forms exist in all dimensions. Except for 1. these representations do not descend from an invariant state of the Weyl algebra and 4. points to a new strategy for solving the quantum constraints.
|
1404.0602
|
Eugenio Bianchi
|
Eugenio Bianchi and Matteo Smerlak
|
Entanglement entropy and negative energy in two dimensions
|
5 pages, 3 figures
|
Phys. Rev. D 90, 041904 (2014)
|
10.1103/PhysRevD.90.041904
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
It is well known that quantum effects can produce negative energy densities,
though for limited times. Here we show in the context of two-dimensional CFT
that such negative energy densities are present in any non-trivial conformal
vacuum and can be interpreted in terms of the entanglement structure of such
states. We derive an exact identity relating the outgoing energy flux and the
entanglement entropy in the in-vacuum. When applied to two-dimensional models
of black hole evaporation, this identity implies that unitarity is incompatible
with monotonic mass loss.
|
[
{
"created": "Wed, 2 Apr 2014 16:15:16 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Apr 2014 17:32:00 GMT",
"version": "v2"
},
{
"created": "Wed, 13 Aug 2014 20:39:56 GMT",
"version": "v3"
}
] |
2014-09-05
|
[
[
"Bianchi",
"Eugenio",
""
],
[
"Smerlak",
"Matteo",
""
]
] |
It is well known that quantum effects can produce negative energy densities, though for limited times. Here we show in the context of two-dimensional CFT that such negative energy densities are present in any non-trivial conformal vacuum and can be interpreted in terms of the entanglement structure of such states. We derive an exact identity relating the outgoing energy flux and the entanglement entropy in the in-vacuum. When applied to two-dimensional models of black hole evaporation, this identity implies that unitarity is incompatible with monotonic mass loss.
|
2304.03263
|
Andrea Giusti
|
Jorge Ovalle, Roberto Casadio, Andrea Giusti
|
Regular hairy black holes through Minkowski deformation
|
8 pages, 3 figures, final version to appear in Phys.Lett.B
| null |
10.1016/j.physletb.2023.138085
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Static and stationary regular black holes are examined under a minimal set of
requirements consisting of (i) the existence of a well defined event horizon
and (ii) the weak energy condition for matter sourcing the geometry. We perform
our analysis by means of the gravitational decoupling approach and find hairy
solutions free of curvature singularities. We identify the matter source
producing a deformation of the Minkowski vacuum such that the maximum
deformation is the Schwarzschild solution for the static case, and the Kerr
metric for the stationary case.
|
[
{
"created": "Thu, 6 Apr 2023 17:47:50 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Jul 2023 05:27:38 GMT",
"version": "v2"
}
] |
2023-07-24
|
[
[
"Ovalle",
"Jorge",
""
],
[
"Casadio",
"Roberto",
""
],
[
"Giusti",
"Andrea",
""
]
] |
Static and stationary regular black holes are examined under a minimal set of requirements consisting of (i) the existence of a well defined event horizon and (ii) the weak energy condition for matter sourcing the geometry. We perform our analysis by means of the gravitational decoupling approach and find hairy solutions free of curvature singularities. We identify the matter source producing a deformation of the Minkowski vacuum such that the maximum deformation is the Schwarzschild solution for the static case, and the Kerr metric for the stationary case.
|
2203.00492
|
Zahra Feizi Mangoudehi
|
Z. Feizi Mangoudehi
|
Interacting Tsallis agegraphic dark energy in DGP Braneworld Cosmology
|
32 pager, 15 figures accepted in Astrophysics and Space Science
|
Astrophys Space Sci 367, 31 (2022) (view-only version link=
https://rdcu.be/cI39R)
|
10.1007/s10509-022-04044-7
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The purpose of this paper is to study the Tsallis agegraphic dark energy with
an interaction term between dark energy and dark matter in the DGP brane-world
scenario. For this, we assume some initial conditions to obtain the dark energy
density, deceleration, dark energy EoS, and total EoS parameters. Then, we
analyze the statefinder parameters, $\omega'{}_{DE}-\omega_{DE}$ plots, and
classical stability features of the model. The results state that the
deceleration parameter provides the phase transition from decelerated to
accelerated phase. The $\omega_{DE}$ graphs show the phantom behavior, while
the $\omega_{tot}$ exhibits the quintessence and phantom during the evolution
of the Universe. Following the graphs, the Statefinder analysis shows the
quintessence behavior of the model for the past and present. However, it tends
to the $\Lambda CDM$ in the following era. The $\omega'{}_{DE}-\omega_{DE}$
plot indicates the thawing or freezing area depending on the type of era and
different values of $b^{2}$, $\delta$, and $m$. By the square of the sound
speed, we see the model is stable in the past, stable or unstable at the
current time, and unstable in the future for selected values of $b^{2}$,
$\delta$, and $m$. To test the model, we use the recent Hubble data. We also
employ Akaike Information Criterion (AIC) and Bayesian Information Criterion
(BIC) to compare the model with the $\Lambda CDM$ as the reference model. In
addition, we test the model using the $H-z$ plot, and we see a turning point in
the future time. The results from the best fit values for the $\omega_{tot}$
plot emphasize that the Universe is in the quintessence region in the current
time. It will enter the phantom phase, and then it will approach the $\Lambda$
state in the future. But, the $\omega_{DE}$ always stays on the phantom region.
The model is unstable in the present and progressive era.
|
[
{
"created": "Tue, 1 Mar 2022 14:39:53 GMT",
"version": "v1"
}
] |
2022-03-17
|
[
[
"Mangoudehi",
"Z. Feizi",
""
]
] |
The purpose of this paper is to study the Tsallis agegraphic dark energy with an interaction term between dark energy and dark matter in the DGP brane-world scenario. For this, we assume some initial conditions to obtain the dark energy density, deceleration, dark energy EoS, and total EoS parameters. Then, we analyze the statefinder parameters, $\omega'{}_{DE}-\omega_{DE}$ plots, and classical stability features of the model. The results state that the deceleration parameter provides the phase transition from decelerated to accelerated phase. The $\omega_{DE}$ graphs show the phantom behavior, while the $\omega_{tot}$ exhibits the quintessence and phantom during the evolution of the Universe. Following the graphs, the Statefinder analysis shows the quintessence behavior of the model for the past and present. However, it tends to the $\Lambda CDM$ in the following era. The $\omega'{}_{DE}-\omega_{DE}$ plot indicates the thawing or freezing area depending on the type of era and different values of $b^{2}$, $\delta$, and $m$. By the square of the sound speed, we see the model is stable in the past, stable or unstable at the current time, and unstable in the future for selected values of $b^{2}$, $\delta$, and $m$. To test the model, we use the recent Hubble data. We also employ Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) to compare the model with the $\Lambda CDM$ as the reference model. In addition, we test the model using the $H-z$ plot, and we see a turning point in the future time. The results from the best fit values for the $\omega_{tot}$ plot emphasize that the Universe is in the quintessence region in the current time. It will enter the phantom phase, and then it will approach the $\Lambda$ state in the future. But, the $\omega_{DE}$ always stays on the phantom region. The model is unstable in the present and progressive era.
|
gr-qc/0310091
|
Pieter Blue
|
P. Blue, A. Soffer
|
Semilinear wave equations on the Schwarzschild manifold I: Local decay
estimates
|
AMS-LaTeX, 16 pages. There is an errata to this paper at
gr-qc/0608073
|
Adv.Diff.Eq. 8 (2003) 595-614
| null | null |
gr-qc
| null |
The semilinear wave equation on the (outer) Schwarzschild manifold is
studied. We prove local decay estimates for general (non-radial) data, deriving
a-priori Morawetz type estimates.
|
[
{
"created": "Sun, 19 Oct 2003 16:33:17 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Aug 2006 22:11:56 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Blue",
"P.",
""
],
[
"Soffer",
"A.",
""
]
] |
The semilinear wave equation on the (outer) Schwarzschild manifold is studied. We prove local decay estimates for general (non-radial) data, deriving a-priori Morawetz type estimates.
|
2303.13302
|
Adam Balcerzak
|
Adam Balcerzak, Mateusz Lisaj
|
Spinor wave function of the Universe in non-minimally coupled varying
constants cosmologies
|
7 pages, 1 figure
| null |
10.1140/epjc/s10052-023-11577-w
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we introduce a non-minimally coupled varying speed of light
and varying gravitational constant cosmological toy model. Using the
Eisenhart-Duval lifting method, we extend the original minisuperspace of the
model and depict the evolution of the system in the presence of the potential
term as a geometrical flow associated with the lifted metric. We write the
Dirac-Wheeler-DeWitt equation, which solution is a spinor wave function of the
Universe. Then we find the solution of the Dirac-Wheeler-DeWitt equation, which
describes the emergence of two early universe-antiuniverse pairs that differ
with the conserved quantity, which is an analog of the spin.
|
[
{
"created": "Thu, 23 Mar 2023 14:39:02 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Mar 2023 12:20:35 GMT",
"version": "v2"
},
{
"created": "Sun, 14 May 2023 08:23:35 GMT",
"version": "v3"
}
] |
2023-05-16
|
[
[
"Balcerzak",
"Adam",
""
],
[
"Lisaj",
"Mateusz",
""
]
] |
In this paper, we introduce a non-minimally coupled varying speed of light and varying gravitational constant cosmological toy model. Using the Eisenhart-Duval lifting method, we extend the original minisuperspace of the model and depict the evolution of the system in the presence of the potential term as a geometrical flow associated with the lifted metric. We write the Dirac-Wheeler-DeWitt equation, which solution is a spinor wave function of the Universe. Then we find the solution of the Dirac-Wheeler-DeWitt equation, which describes the emergence of two early universe-antiuniverse pairs that differ with the conserved quantity, which is an analog of the spin.
|
2110.12188
|
Mert Mangut
|
Ozay Gurtug, Mustafa Halilsoy and Mert Mangut
|
The Charged Zipoy-Voorhees Metric with Astrophysical Applications
|
New sections are added and supported with new graphs. Typos are
corrected. Matched with published version
|
Eur. Phys. J. C 82, 671 (2022)
|
10.1140/epjc/s10052-022-10626-0
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Starting from an integral of the interaction region of colliding
Einstein-Maxwell waves and by applying a coordinate transformation, we obtain
the charged version of the static Zipoy-Voorhees (ZV) metric valid for all
values of the distortion parameter $\gamma$. In Schwarzschild coordinates, we
investigate the effect of the charge in the newly found spacetime, stress the
analogy with Reissner - Nordstrom metric and discuss some of its features. It
is shown that from the expression of Weyl curvature, directional singularities
become manifest. For astrophysical importance, we find lensing of null
geodesics from the Gauss - Bonnet theorem in such non - spherically charged
objects. To prepare the ground for our null, circular geodesics we consider the
angular equation linearized about the symmetry plane $\theta=\pi/2$. This, in
turn, suggests the distortion parameter (the $ZV$ parameter) must be in the
interval $1/2<\gamma<1$. It is found that the lensing angle is highly dependent
on the distortion parameter, and becomes decisive on the effect of the charge.
For a class of charged compact stars, we plot the deflection angle versus the
ratio of impact parameter to the radius of the star. Plots have revealed that
for perfectly spherical compact stars, it is hard to identify the effect of
electric/magnetic charge, but for non-spherical compact stars the effect of
electric charge becomes apparent. For comparison, the same lensing angle has
also been found for the stationary ZV metric in the equatorial plane. Our
analysis indicates that depending on the value of $\gamma$, the stationary
state induces counter effect on the bending angle and thus, when compared with
the uncharged static ZV case, the bending angle decreases. The influence of the
parameter $\gamma$ on the gravitational redshift is also displayed.
|
[
{
"created": "Sat, 23 Oct 2021 10:05:07 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Dec 2021 20:02:09 GMT",
"version": "v2"
},
{
"created": "Tue, 8 Feb 2022 14:13:05 GMT",
"version": "v3"
},
{
"created": "Tue, 9 Aug 2022 15:01:31 GMT",
"version": "v4"
}
] |
2022-08-10
|
[
[
"Gurtug",
"Ozay",
""
],
[
"Halilsoy",
"Mustafa",
""
],
[
"Mangut",
"Mert",
""
]
] |
Starting from an integral of the interaction region of colliding Einstein-Maxwell waves and by applying a coordinate transformation, we obtain the charged version of the static Zipoy-Voorhees (ZV) metric valid for all values of the distortion parameter $\gamma$. In Schwarzschild coordinates, we investigate the effect of the charge in the newly found spacetime, stress the analogy with Reissner - Nordstrom metric and discuss some of its features. It is shown that from the expression of Weyl curvature, directional singularities become manifest. For astrophysical importance, we find lensing of null geodesics from the Gauss - Bonnet theorem in such non - spherically charged objects. To prepare the ground for our null, circular geodesics we consider the angular equation linearized about the symmetry plane $\theta=\pi/2$. This, in turn, suggests the distortion parameter (the $ZV$ parameter) must be in the interval $1/2<\gamma<1$. It is found that the lensing angle is highly dependent on the distortion parameter, and becomes decisive on the effect of the charge. For a class of charged compact stars, we plot the deflection angle versus the ratio of impact parameter to the radius of the star. Plots have revealed that for perfectly spherical compact stars, it is hard to identify the effect of electric/magnetic charge, but for non-spherical compact stars the effect of electric charge becomes apparent. For comparison, the same lensing angle has also been found for the stationary ZV metric in the equatorial plane. Our analysis indicates that depending on the value of $\gamma$, the stationary state induces counter effect on the bending angle and thus, when compared with the uncharged static ZV case, the bending angle decreases. The influence of the parameter $\gamma$ on the gravitational redshift is also displayed.
|
gr-qc/0301100
|
Jian Qi Shen
|
Jian-Qi Shen
|
Dynamics of Gravitomagnetic Charge
|
10 pages, Latex. This paper was not published. For the relevant
papers, see: General Relativity and Gravitation 34: 1423-1435 (2002); Annalen
der Physik 13: 532-553 (2004)
| null | null | null |
gr-qc
| null |
The physically interesting gravitational analogue of magnetic monopole in
electrodynamics is considered in the present paper. The author investigates the
field equation of gravitomagnetic matter, and the exact static cylindrically
symmetric solution of field equation as well as the motion of gravitomagnetic
charge in gravitational fields. Use is made of the mechanism of gravitational
Meissner effect, a potential interpretation of anomalous, constant,
acceleration acting on the Pioneer 10/11, Galileo and Ulysses spacecrafts is
also suggested.
|
[
{
"created": "Fri, 24 Jan 2003 08:22:59 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Jan 2003 07:36:45 GMT",
"version": "v2"
}
] |
2015-09-14
|
[
[
"Shen",
"Jian-Qi",
""
]
] |
The physically interesting gravitational analogue of magnetic monopole in electrodynamics is considered in the present paper. The author investigates the field equation of gravitomagnetic matter, and the exact static cylindrically symmetric solution of field equation as well as the motion of gravitomagnetic charge in gravitational fields. Use is made of the mechanism of gravitational Meissner effect, a potential interpretation of anomalous, constant, acceleration acting on the Pioneer 10/11, Galileo and Ulysses spacecrafts is also suggested.
|
gr-qc/9903040
|
Hans-Jurgen Matschull
|
Hans-Juergen Matschull
|
On the relation between 2+1 Einstein gravity and Chern Simons theory
|
14 pages, LaTeX2e, 3 eps figures
|
Class.Quant.Grav. 16 (1999) 2599-2609
|
10.1088/0264-9381/16/8/303
|
MZ-TH/99-04
|
gr-qc
| null |
A simple example is given to show that the gauge equivalence classes of
physical states in Chern Simons theory are not in one-to-one correspondence
with those of Einstein gravity in three spacetime dimensions. The two theories
are therefore not equivalent. It is shown that including singular metrics into
general relativity has more, and in fact a quite counter-intuitive, impact on
the theory than one naively expects.
|
[
{
"created": "Thu, 11 Mar 1999 13:12:00 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Matschull",
"Hans-Juergen",
""
]
] |
A simple example is given to show that the gauge equivalence classes of physical states in Chern Simons theory are not in one-to-one correspondence with those of Einstein gravity in three spacetime dimensions. The two theories are therefore not equivalent. It is shown that including singular metrics into general relativity has more, and in fact a quite counter-intuitive, impact on the theory than one naively expects.
|
2408.06176
|
Allan Alinea
|
Allan L. Alinea, Joshwa DJ. Ordonez
|
On the KG-constrained general disformal transformation of the
Einstein-Hilbert action
|
15 pages
| null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
Although with great successes in explaining phenomena and natural behaviour
involving the Universe or a part thereof, the General Theory of Relativity is
far from a complete theory. There are plenty of avenues to investigate its
extensions or generalisations that, in the future, could pave the way for a
much deeper understanding and possibly solutions of current problems involving
the Universe; e.g., dark matter, dark energy, fine-tuning, etc. Focusing on its
extension within the framework of scalar tensor theory, we investigate the
transformation of the Einstein-Hilbert action under the general disformal
transformation coupled with set of triple KG constraints. The idea is that the
general disformal transformation leads to an extremely complicated action
necessitating a set of constraints to tame the resulting form. Motivated by
previous studies on the invertibility and invariance of the massless
Klein-Gordon equation under the general disformal transformation, we identify
three constraints that significantly simplifies the transformed
Einstein-Hilbert action. In four spacetime dimensions, we find that the
transformed action is a sum of the original action and a disformal contribution
involving a six-term Lagrangian that includes the Ricci tensor coupled to a sum
of derivatives of scalar fields and kinetic terms. In three spacetime
dimensions, the disformal contribution becomes a five-term Lagrangian. Lastly,
in two spacetime dimensions, the Einstein-Hilbert action is invariant under the
constrained disformal transformation.
|
[
{
"created": "Mon, 12 Aug 2024 14:22:53 GMT",
"version": "v1"
}
] |
2024-08-13
|
[
[
"Alinea",
"Allan L.",
""
],
[
"Ordonez",
"Joshwa DJ.",
""
]
] |
Although with great successes in explaining phenomena and natural behaviour involving the Universe or a part thereof, the General Theory of Relativity is far from a complete theory. There are plenty of avenues to investigate its extensions or generalisations that, in the future, could pave the way for a much deeper understanding and possibly solutions of current problems involving the Universe; e.g., dark matter, dark energy, fine-tuning, etc. Focusing on its extension within the framework of scalar tensor theory, we investigate the transformation of the Einstein-Hilbert action under the general disformal transformation coupled with set of triple KG constraints. The idea is that the general disformal transformation leads to an extremely complicated action necessitating a set of constraints to tame the resulting form. Motivated by previous studies on the invertibility and invariance of the massless Klein-Gordon equation under the general disformal transformation, we identify three constraints that significantly simplifies the transformed Einstein-Hilbert action. In four spacetime dimensions, we find that the transformed action is a sum of the original action and a disformal contribution involving a six-term Lagrangian that includes the Ricci tensor coupled to a sum of derivatives of scalar fields and kinetic terms. In three spacetime dimensions, the disformal contribution becomes a five-term Lagrangian. Lastly, in two spacetime dimensions, the Einstein-Hilbert action is invariant under the constrained disformal transformation.
|
2309.07342
|
Serban Cicortas
|
Serban Cicortas
|
Scattering for the Wave Equation on de Sitter Space in All Even Spatial
Dimensions
|
37 pages; minor corrections and added references for section 1
| null | null | null |
gr-qc math.AP
|
http://creativecommons.org/licenses/by/4.0/
|
For any $n\geq4$ even, we establish a complete scattering theory for the
linear wave equation on the $(n+1)$-dimensional de Sitter space. We prove the
existence and uniqueness of scattering states, and asymptotic completeness.
Moreover, we construct the scattering map taking asymptotic data at past
infinity $\mathscr{I}^-$ to asymptotic data at future infinity $\mathscr{I}^+$.
Identifying $\mathscr{I}^-$ and $\mathscr{I}^+$ with $S^n,$ we prove that the
scattering map is a Banach space isomorphism on $H^{s+n}(S^n)\times
H^{s}(S^n),$ for any $s\geq1.$
The main analysis is carried out at the level of the model equation obtained
by differentiating the linear wave equation $\frac{n}{2}$ times in the time
variable. The main result of the paper follows from proving a scattering theory
for this equation. In particular, for the model equation we construct a
scattering isomorphism from asymptotic data in $H^{s+\frac{1}{2}}(S^n)\times
H^s(S^n)\times H^s(S^n)$ to Cauchy initial data in
$H^{s+\frac{1}{2}}(S^n)\times H^{s+\frac{1}{2}}(S^n)\times
H^{s-\frac{1}{2}}(S^n)$.
|
[
{
"created": "Wed, 13 Sep 2023 22:43:20 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Sep 2023 22:05:56 GMT",
"version": "v2"
},
{
"created": "Wed, 8 May 2024 18:21:05 GMT",
"version": "v3"
}
] |
2024-05-10
|
[
[
"Cicortas",
"Serban",
""
]
] |
For any $n\geq4$ even, we establish a complete scattering theory for the linear wave equation on the $(n+1)$-dimensional de Sitter space. We prove the existence and uniqueness of scattering states, and asymptotic completeness. Moreover, we construct the scattering map taking asymptotic data at past infinity $\mathscr{I}^-$ to asymptotic data at future infinity $\mathscr{I}^+$. Identifying $\mathscr{I}^-$ and $\mathscr{I}^+$ with $S^n,$ we prove that the scattering map is a Banach space isomorphism on $H^{s+n}(S^n)\times H^{s}(S^n),$ for any $s\geq1.$ The main analysis is carried out at the level of the model equation obtained by differentiating the linear wave equation $\frac{n}{2}$ times in the time variable. The main result of the paper follows from proving a scattering theory for this equation. In particular, for the model equation we construct a scattering isomorphism from asymptotic data in $H^{s+\frac{1}{2}}(S^n)\times H^s(S^n)\times H^s(S^n)$ to Cauchy initial data in $H^{s+\frac{1}{2}}(S^n)\times H^{s+\frac{1}{2}}(S^n)\times H^{s-\frac{1}{2}}(S^n)$.
|
gr-qc/9907099
|
Mark E. Rupright
|
Arlen Anderson, Yvonne Choquet-Bruhat, and James W. York Jr
|
Einstein's Equations and Equivalent Hyperbolic Dynamical Systems
|
30 pages, LaTeX2e, to be published in the Proceedings of the 2nd
Samos Meeting. (Errors in previous version corrected)
| null | null | null |
gr-qc
| null |
We discuss several explicitly causal hyperbolic formulations of Einstein's
dynamical 3+1 equations in a coherent way, emphasizing throughout the
fundamental role of the ``slicing function,'' $\alpha$---the quantity that
relates the lapse $N$ to the determinant of the spatial metric $\bar{g}$
through $N = \bar{g}^{1/2} \alpha$. The slicing function allows us to
demonstrate explicitly that every foliation of spacetime by spatial time-slices
can be used in conjunction with the causal hyperbolic forms of the dynamical
Einstein equations. Specifically, the slicing function plays an essential role
(1) in a clearer form of the canonical action principle and Hamiltonian
dynamics for gravity and leads to a recasting (2) of the Bianchi identities
$\nabla_\beta G^\beta\mathstrut_\alpha \equiv 0$ as a well-posed system for the
evolution of the gravitational constraints in vacuum, and also (3) of
$\nabla_\beta T^\beta\mathstrut_\alpha \equiv 0$ as a well-posed system for
evolution of the energy and momentum components of the stress tensor in the
presence of matter, (4) in an explicit rendering of four hyperbolic
formulations of Einstein's equations with only physical characteristics, and
(5) in providing guidance to a new ``conformal thin sandwich'' form of the
initial value constraints.
|
[
{
"created": "Wed, 28 Jul 1999 19:37:54 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Aug 1999 18:34:28 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Anderson",
"Arlen",
""
],
[
"Choquet-Bruhat",
"Yvonne",
""
],
[
"York",
"James W.",
"Jr"
]
] |
We discuss several explicitly causal hyperbolic formulations of Einstein's dynamical 3+1 equations in a coherent way, emphasizing throughout the fundamental role of the ``slicing function,'' $\alpha$---the quantity that relates the lapse $N$ to the determinant of the spatial metric $\bar{g}$ through $N = \bar{g}^{1/2} \alpha$. The slicing function allows us to demonstrate explicitly that every foliation of spacetime by spatial time-slices can be used in conjunction with the causal hyperbolic forms of the dynamical Einstein equations. Specifically, the slicing function plays an essential role (1) in a clearer form of the canonical action principle and Hamiltonian dynamics for gravity and leads to a recasting (2) of the Bianchi identities $\nabla_\beta G^\beta\mathstrut_\alpha \equiv 0$ as a well-posed system for the evolution of the gravitational constraints in vacuum, and also (3) of $\nabla_\beta T^\beta\mathstrut_\alpha \equiv 0$ as a well-posed system for evolution of the energy and momentum components of the stress tensor in the presence of matter, (4) in an explicit rendering of four hyperbolic formulations of Einstein's equations with only physical characteristics, and (5) in providing guidance to a new ``conformal thin sandwich'' form of the initial value constraints.
|
1606.05295
|
Sebasti\'an Bahamonde
|
Sebastian Bahamonde, Mubasher Jamil, Petar Pavlovic, Marko Sossich
|
Cosmological wormholes in $f(R)$ theories of gravity
|
Slighly updated version. Accepted for publication in Physical Review
D
|
Phys. Rev. D 94, 044041 (2016)
|
10.1103/PhysRevD.94.044041
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Motivated by recent proposals of possible wormhole existence in galactic
halos, we analyse the cosmological evolution of wormhole solutions in modified
$f(R)$ gravity. We construct a dynamical wormhole that asymptotically
approaches FLRW universe, with supporting material going to the perfect
isotropic fluid described by the equation of state for radiation and matter
dominated universe respectively. Our analysis is based on an approximation of a
small wormhole - a wormhole that can be treated as matched with the FLRW metric
at some radial coordinate much smaller than the Hubble radius, so that
cosmological boundary conditions are satisfied. With a special interest in
viable wormhole solutions, we refer to the results of reconstruction procedure
and use $f(R)$ functions which lead to the experimentally confirmed
$\Lambda$CDM expansion history of the Universe. Solutions we find imply no need
for exotic matter near the throat of considered wormholes, while in the limit
of $f(R)=R$ this need is always present during radiation and matter dominated
epoch.
|
[
{
"created": "Thu, 16 Jun 2016 18:01:17 GMT",
"version": "v1"
},
{
"created": "Sun, 7 Aug 2016 17:52:25 GMT",
"version": "v2"
}
] |
2016-08-24
|
[
[
"Bahamonde",
"Sebastian",
""
],
[
"Jamil",
"Mubasher",
""
],
[
"Pavlovic",
"Petar",
""
],
[
"Sossich",
"Marko",
""
]
] |
Motivated by recent proposals of possible wormhole existence in galactic halos, we analyse the cosmological evolution of wormhole solutions in modified $f(R)$ gravity. We construct a dynamical wormhole that asymptotically approaches FLRW universe, with supporting material going to the perfect isotropic fluid described by the equation of state for radiation and matter dominated universe respectively. Our analysis is based on an approximation of a small wormhole - a wormhole that can be treated as matched with the FLRW metric at some radial coordinate much smaller than the Hubble radius, so that cosmological boundary conditions are satisfied. With a special interest in viable wormhole solutions, we refer to the results of reconstruction procedure and use $f(R)$ functions which lead to the experimentally confirmed $\Lambda$CDM expansion history of the Universe. Solutions we find imply no need for exotic matter near the throat of considered wormholes, while in the limit of $f(R)=R$ this need is always present during radiation and matter dominated epoch.
|
gr-qc/0509127
|
Aharon Davidson
|
Aharon Davidson, David Karasik, and Yoav Lederer
|
Geodesic Nucleation and Evolution of a de Sitter Brane
|
5 PRD pages, 4 eps figures
|
Phys.Rev.D72:064011,2005
|
10.1103/PhysRevD.72.064011
| null |
gr-qc
| null |
Within the framework of Geodesic Brane Gravity, the deviation from General
Relativity is parameterized by the conserved bulk energy. The corresponding
geodesic evolution/nucleation of a de-Sitter brane is shown to be exclusively
driven by a double-well Higgs potential, rather than by a plain cosmological
constant. The (hairy) horizon serves then as the locus of unbroken $Z_{2}$
symmetry. The quartic structure of the scalar potential, singled out on
finiteness grounds of the total (including the dark component) energy density,
chooses the Hartle-Hawking no-boundary proposal.
|
[
{
"created": "Fri, 30 Sep 2005 15:05:16 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Davidson",
"Aharon",
""
],
[
"Karasik",
"David",
""
],
[
"Lederer",
"Yoav",
""
]
] |
Within the framework of Geodesic Brane Gravity, the deviation from General Relativity is parameterized by the conserved bulk energy. The corresponding geodesic evolution/nucleation of a de-Sitter brane is shown to be exclusively driven by a double-well Higgs potential, rather than by a plain cosmological constant. The (hairy) horizon serves then as the locus of unbroken $Z_{2}$ symmetry. The quartic structure of the scalar potential, singled out on finiteness grounds of the total (including the dark component) energy density, chooses the Hartle-Hawking no-boundary proposal.
|
1207.5359
|
Lorenzo De Vittori
|
Lorenzo De Vittori, Philippe Jetzer, Antoine Klein
|
Gravitational wave energy spectrum of hyperbolic encounters
|
9 pages, 4 figures, Accepted for publication in Physical Review D
|
Phys.Rev.D 86 (2012) 044017
|
10.1103/PhysRevD.86.044017
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The emission of gravitational waves is studied for a system of massive
objects interacting on hyperbolic orbits within the quadrupole approximation
following the work of Capozziello et al. Here we focus on the derivation of an
analytic formula for the energy spectrum of the emitted waves. We checked
numerically that our formula is in agreement with the two limiting cases for
which results were already available: for the eccentricity {\epsilon} = 1, the
parabolic case whose spectrum was computed by Berry and Gair, and the large
{\epsilon} limit with the formula given by Turner.
|
[
{
"created": "Mon, 23 Jul 2012 11:27:58 GMT",
"version": "v1"
}
] |
2012-08-13
|
[
[
"De Vittori",
"Lorenzo",
""
],
[
"Jetzer",
"Philippe",
""
],
[
"Klein",
"Antoine",
""
]
] |
The emission of gravitational waves is studied for a system of massive objects interacting on hyperbolic orbits within the quadrupole approximation following the work of Capozziello et al. Here we focus on the derivation of an analytic formula for the energy spectrum of the emitted waves. We checked numerically that our formula is in agreement with the two limiting cases for which results were already available: for the eccentricity {\epsilon} = 1, the parabolic case whose spectrum was computed by Berry and Gair, and the large {\epsilon} limit with the formula given by Turner.
|
1606.06605
|
Francesco Becattini
|
F. Becattini
|
Thermodynamic equilibrium in relativity: four-temperature, Killing
vectors and Lie derivatives
|
13 pages
| null |
10.5506/APhysPolB.47.1819
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The main concepts of general relativistic thermodynamics and general
relativistic statistical mechanics are reviewed. The main building block of the
proper relativistic extension of the classical thermodynamics laws is the
four-temperature vector \beta, which plays a major role in the quantum
framework and defines a very convenient hydrodynamic frame. The general
relativistic thermodynamic equilibrium condition demands \beta to be a Killing
vector field. We show that a remarkable consequence is that all Lie derivatives
of all physical observables along the four-temperature flow must then vanish.
|
[
{
"created": "Tue, 21 Jun 2016 14:56:42 GMT",
"version": "v1"
}
] |
2016-08-24
|
[
[
"Becattini",
"F.",
""
]
] |
The main concepts of general relativistic thermodynamics and general relativistic statistical mechanics are reviewed. The main building block of the proper relativistic extension of the classical thermodynamics laws is the four-temperature vector \beta, which plays a major role in the quantum framework and defines a very convenient hydrodynamic frame. The general relativistic thermodynamic equilibrium condition demands \beta to be a Killing vector field. We show that a remarkable consequence is that all Lie derivatives of all physical observables along the four-temperature flow must then vanish.
|
1007.3368
|
Julian Barbour
|
Julian Barbour
|
The Definition of Mach's Principle
|
To be published in Foundations of Physics as invited contribution to
Peter Mittelstaedt's 80th Birthday Festschrift. 30 pages
|
Found.Phys.40:1263-1284,2010
|
10.1007/s10701-010-9490-7
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Two definitions of Mach's principle are proposed. Both are related to gauge
theory, are universal in scope and amount to formulations of causality that
take into account the relational nature of position, time, and size. One of
them leads directly to general relativity and may have relevance to the problem
of creating a quantum theory of gravity.
|
[
{
"created": "Tue, 20 Jul 2010 09:14:50 GMT",
"version": "v1"
}
] |
2014-11-21
|
[
[
"Barbour",
"Julian",
""
]
] |
Two definitions of Mach's principle are proposed. Both are related to gauge theory, are universal in scope and amount to formulations of causality that take into account the relational nature of position, time, and size. One of them leads directly to general relativity and may have relevance to the problem of creating a quantum theory of gravity.
|
gr-qc/0603130
|
Spiros Cotsakis
|
Spiros Cotsakis and Ifigeneia Klaoudatou
|
Singular Isotropic Cosmologies and Bel-Robinson Energy
|
13 pages, to appear in the Proceedings of the A. Einstein Century
International Conference, Paris, France, July 18-22, 2005
| null |
10.1063/1.2399667
|
RG-MPC/060331-1
|
gr-qc
| null |
We consider the problem of the nature and possible types of spacetime
singularities that can form during the evolution of \emph{FRW} universes in
general relativity. We show that by using, in addition to the Hubble expansion
rate and the scale factor, the Bel-Robinson energy of these universes we can
consistently distinguish between the possible different types of singularities
and arrive at a complete classification of the singularities that can occur in
the isotropic case. We also use the Bel-Robinson energy to prove that known
behaviours of exact flat isotropic universes with given singularities are
generic in the sense that they hold true in every type of spatial geometry.
|
[
{
"created": "Fri, 31 Mar 2006 10:40:45 GMT",
"version": "v1"
}
] |
2009-11-11
|
[
[
"Cotsakis",
"Spiros",
""
],
[
"Klaoudatou",
"Ifigeneia",
""
]
] |
We consider the problem of the nature and possible types of spacetime singularities that can form during the evolution of \emph{FRW} universes in general relativity. We show that by using, in addition to the Hubble expansion rate and the scale factor, the Bel-Robinson energy of these universes we can consistently distinguish between the possible different types of singularities and arrive at a complete classification of the singularities that can occur in the isotropic case. We also use the Bel-Robinson energy to prove that known behaviours of exact flat isotropic universes with given singularities are generic in the sense that they hold true in every type of spatial geometry.
|
1111.5274
|
Tjonnie Guang Feng Li
|
T. G. F. Li, W. Del Pozzo, S. Vitale, C. Van Den Broeck, M. Agathos,
J. Veitch, K. Grover, T. Sidery, R. Sturani, A. Vecchio
|
Towards a generic test of the strong field dynamics of general
relativity using compact binary coalescence: Further investigations
|
15 pages, 7 figures, Amaldi 9 proceedings
| null |
10.1088/1742-6596/363/1/012028
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we elaborate on earlier work by the same authors in which a
novel Bayesian inference framework for testing the strong-field dynamics of
General Relativity using coalescing compact binaries was proposed. Unlike
methods that were used previously, our technique addresses the question whether
one or more 'testing coefficients' (e.g. in the phase) parameterizing
deviations from GR are non-zero, rather than all of them differing from zero at
the same time. The framework is well-adapted to a scenario where most sources
have low signal-to-noise ratio, and information from multiple sources as seen
in multiple detectors can readily be combined. In our previous work, we
conjectured that this framework can detect generic deviations from GR that can
in principle not be accomodated by our model waveforms, on condition that the
change in phase near frequencies where the detectors are the most sensitive is
comparable to that induced by simple shifts in the lower-order phase
coefficients of more than a few percent ($\sim 5$ radians at 150 Hz). To
further support this claim, we perform additional numerical experiments in
Gaussian and stationary noise according to the expected Advanced LIGO/Virgo
noise curves, and coherently injecting signals into the network whose phasing
differs structurally from the predictions of GR, but with the magnitude of the
deviation still being small. We find that even then, a violation of GR can be
established with good confidence.
|
[
{
"created": "Tue, 22 Nov 2011 18:29:40 GMT",
"version": "v1"
},
{
"created": "Thu, 3 May 2012 22:05:16 GMT",
"version": "v2"
}
] |
2015-06-03
|
[
[
"Li",
"T. G. F.",
""
],
[
"Del Pozzo",
"W.",
""
],
[
"Vitale",
"S.",
""
],
[
"Broeck",
"C. Van Den",
""
],
[
"Agathos",
"M.",
""
],
[
"Veitch",
"J.",
""
],
[
"Grover",
"K.",
""
],
[
"Sidery",
"T.",
""
],
[
"Sturani",
"R.",
""
],
[
"Vecchio",
"A.",
""
]
] |
In this paper we elaborate on earlier work by the same authors in which a novel Bayesian inference framework for testing the strong-field dynamics of General Relativity using coalescing compact binaries was proposed. Unlike methods that were used previously, our technique addresses the question whether one or more 'testing coefficients' (e.g. in the phase) parameterizing deviations from GR are non-zero, rather than all of them differing from zero at the same time. The framework is well-adapted to a scenario where most sources have low signal-to-noise ratio, and information from multiple sources as seen in multiple detectors can readily be combined. In our previous work, we conjectured that this framework can detect generic deviations from GR that can in principle not be accomodated by our model waveforms, on condition that the change in phase near frequencies where the detectors are the most sensitive is comparable to that induced by simple shifts in the lower-order phase coefficients of more than a few percent ($\sim 5$ radians at 150 Hz). To further support this claim, we perform additional numerical experiments in Gaussian and stationary noise according to the expected Advanced LIGO/Virgo noise curves, and coherently injecting signals into the network whose phasing differs structurally from the predictions of GR, but with the magnitude of the deviation still being small. We find that even then, a violation of GR can be established with good confidence.
|
1504.07817
|
Jose Geraldo Pereira
|
H. Arcos, M. Krssak, J. G. Pereira
|
Exploring Higher-Order Gravitational Waves
|
12 pages, no figures
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In addition to the usual linear gravitational waves in transverse-traceless
coordinates, higher-order gravitational field equations, as well as their
corresponding solutions, are explicitly obtained. It is found that higher-order
waves do not represent corrections to the first-order wave. In contrast, all
higher than second-order solutions do represent corrections to the second-order
wave, a property that makes the first-order gravitational wave to stand apart
from higher-order waves. Furthermore, although the first-order solution is
transverse and traceless, all higher-order solutions are not. As a consequence,
the whole solution is neither transverse nor traceless, a result that could
eventually have important consequences for quantum gravity, and in particular
for the definition of graviton itself. Some additional properties and features
of these higher-order gravitational waves are explored and discussed.
|
[
{
"created": "Wed, 29 Apr 2015 11:42:08 GMT",
"version": "v1"
}
] |
2015-04-30
|
[
[
"Arcos",
"H.",
""
],
[
"Krssak",
"M.",
""
],
[
"Pereira",
"J. G.",
""
]
] |
In addition to the usual linear gravitational waves in transverse-traceless coordinates, higher-order gravitational field equations, as well as their corresponding solutions, are explicitly obtained. It is found that higher-order waves do not represent corrections to the first-order wave. In contrast, all higher than second-order solutions do represent corrections to the second-order wave, a property that makes the first-order gravitational wave to stand apart from higher-order waves. Furthermore, although the first-order solution is transverse and traceless, all higher-order solutions are not. As a consequence, the whole solution is neither transverse nor traceless, a result that could eventually have important consequences for quantum gravity, and in particular for the definition of graviton itself. Some additional properties and features of these higher-order gravitational waves are explored and discussed.
|
gr-qc/0511032
|
Choquet-Bruhat
|
Yvonne Choquet-Bruhat and James W. York
|
Einstein Bianchi equations with sources
|
submitted for special issue of Circolo Matematico di Palermo in honor
of Guy Boilla
| null | null | null |
gr-qc
| null |
In this article, dedicated to one of the best specialist of the FOSH systems,
we couple the Bianchi equations with the equations satisfied by the dynamical
acceleration of a charged fluid and the derivatives of the associated Maxwell
field.
|
[
{
"created": "Mon, 7 Nov 2005 13:14:25 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Choquet-Bruhat",
"Yvonne",
""
],
[
"York",
"James W.",
""
]
] |
In this article, dedicated to one of the best specialist of the FOSH systems, we couple the Bianchi equations with the equations satisfied by the dynamical acceleration of a charged fluid and the derivatives of the associated Maxwell field.
|
2008.07040
|
Marco Maceda
|
Marco Maceda and Alfredo Mac\'ias and Daniel Mart\'inez-Carbajal
|
Shadow of a noncommutative inspired Einstein-Euler-Heisenberg black hole
|
8 pages, 5 figures; minor modifications, some typos corrected
| null |
10.1142/S0217751X21501918
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Using a noncommutative inspired Einstein-Euler-Heisenberg black hole, we
analyse the associated graviton and light rings that together with the event
horizon, provide the necessary components to build its shadow. An analysis of
the angular radius of the noncommutative inspired Einstein-Euler-Heisenberg
black hole shows that for observers located in its vicinity, it becomes smaller
when compared with the commutative case; this effect is more noticeable as
noncommutativity increases. The existence of marginally stable bound orbits and
the critical angle for the escaping of photons of a noncommutative inspired
Einstein-Euler-Heisenberg star is also discussed.
|
[
{
"created": "Mon, 17 Aug 2020 00:52:30 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Aug 2020 19:32:29 GMT",
"version": "v2"
}
] |
2021-10-27
|
[
[
"Maceda",
"Marco",
""
],
[
"Macías",
"Alfredo",
""
],
[
"Martínez-Carbajal",
"Daniel",
""
]
] |
Using a noncommutative inspired Einstein-Euler-Heisenberg black hole, we analyse the associated graviton and light rings that together with the event horizon, provide the necessary components to build its shadow. An analysis of the angular radius of the noncommutative inspired Einstein-Euler-Heisenberg black hole shows that for observers located in its vicinity, it becomes smaller when compared with the commutative case; this effect is more noticeable as noncommutativity increases. The existence of marginally stable bound orbits and the critical angle for the escaping of photons of a noncommutative inspired Einstein-Euler-Heisenberg star is also discussed.
|
gr-qc/0702035
|
David W. Neilsen
|
David Neilsen, Eric W. Hirschmann, Matthew Anderson, and Steven L.
Liebling
|
Adaptive Mesh Refinement and Relativistic MHD
|
3 Pages, Proceedings of the Marcel Grossmann Meeting XI
| null |
10.1142/9789812834300_0200
| null |
gr-qc
| null |
We solve the general relativistic magnetohydrodynamics equations using
distributed parallel adaptive mesh refinement. We discuss strong scaling tests
of the code, and present evolutions of Michel accretion and a TOV star.
|
[
{
"created": "Tue, 6 Feb 2007 20:55:07 GMT",
"version": "v1"
}
] |
2016-11-15
|
[
[
"Neilsen",
"David",
""
],
[
"Hirschmann",
"Eric W.",
""
],
[
"Anderson",
"Matthew",
""
],
[
"Liebling",
"Steven L.",
""
]
] |
We solve the general relativistic magnetohydrodynamics equations using distributed parallel adaptive mesh refinement. We discuss strong scaling tests of the code, and present evolutions of Michel accretion and a TOV star.
|
0905.3833
|
H\'ector Calder\'on
|
H\'ector H. Calder\'on
|
The Reciprocal of the Fundamental Theorem of Riemannian Geometry
|
6 pages
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The fundamental theorem of Riemannian geometry is inverted for analytic
Christoffel symbols. The inversion formula, henceforth dubbed Ricardo's
formula, is obtained without ancillary assumptions. Even though Ricardo's
formula can mathematically give the full answer, it is argued that the solution
should be taken only up to a constant conformal factor. A procedure to obtain
the Christoffel symbols out of unparameterized geodesics is sketched. Thus, a
complete framework to obtain the metric out of measurements is presented. The
framework is suitable for analysis of experiments testing the geometrical
nature of gravity.
|
[
{
"created": "Sat, 23 May 2009 16:48:27 GMT",
"version": "v1"
}
] |
2009-05-26
|
[
[
"Calderón",
"Héctor H.",
""
]
] |
The fundamental theorem of Riemannian geometry is inverted for analytic Christoffel symbols. The inversion formula, henceforth dubbed Ricardo's formula, is obtained without ancillary assumptions. Even though Ricardo's formula can mathematically give the full answer, it is argued that the solution should be taken only up to a constant conformal factor. A procedure to obtain the Christoffel symbols out of unparameterized geodesics is sketched. Thus, a complete framework to obtain the metric out of measurements is presented. The framework is suitable for analysis of experiments testing the geometrical nature of gravity.
|
1102.0117
|
Remo Garattini
|
Remo Garattini
|
Modified Dispersion Relations and Noncommutative Geometry lead to a
finite Zero Point Energy
|
Contribution written for the Proceedings of Frontiers of Fundamental
Physics [FFP11], 6-9 July 2010, Paris. 12 Pages
| null |
10.1063/1.4728001
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We compute Zero Point Energy in a spherically symmetric background with the
help of the Wheeler-DeWitt equation. This last one is regarded as a
Sturm-Liouville problem with the cosmological constant considered as the
associated eigenvalue. The graviton contribution, at one loop is extracted wit
the help of a variational approach together with Gaussian trial functionals.
The divergences handled with a zeta function regularization are compared with
the results obtained using a Noncommutative Geometry (NCG) and Modified
Dispersion Relations (MDR). In both NCG and MDR no renormalization scheme is
necessary to remove infinities in contrast to what happens in conventional
approaches.
|
[
{
"created": "Tue, 1 Feb 2011 10:17:25 GMT",
"version": "v1"
}
] |
2015-05-27
|
[
[
"Garattini",
"Remo",
""
]
] |
We compute Zero Point Energy in a spherically symmetric background with the help of the Wheeler-DeWitt equation. This last one is regarded as a Sturm-Liouville problem with the cosmological constant considered as the associated eigenvalue. The graviton contribution, at one loop is extracted wit the help of a variational approach together with Gaussian trial functionals. The divergences handled with a zeta function regularization are compared with the results obtained using a Noncommutative Geometry (NCG) and Modified Dispersion Relations (MDR). In both NCG and MDR no renormalization scheme is necessary to remove infinities in contrast to what happens in conventional approaches.
|
1903.08809
|
Pitayuth Wongjun
|
Sushant G. Ghosh, Rahul Kumar, Lunchakorn Tannukij, Pitayuth Wongjun
|
Rotating black string in dRGT massive gravity
|
27 pages, 18 figures; V2 minor change, two column, 14 pages, 18
figures,V3 more information and discussion added, V4 minor change, matched
with PRD
|
Phys. Rev. D 101, 104042 (2020)
|
10.1103/PhysRevD.101.104042
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
One of the solutions of Einstein field equation with cylindrical symmetry is
known as black string solution. In this work, the rotating black string
solution in dRGT massive gravity is obtained and then called rotating-dRGT
black string solution. This solution is a kind of generalized version of
rotating AdS/dS black sting solution containing an additional two more terms
characterizing the structure of graviton mass. The horizon structures of the
black string are explored. The thermodynamical properties of the black string
are investigated. We found that it is possible to obtain the Hawking-Page phase
transition depending on the additional structure of the graviton mass, while it
is not possible for rotating-AdS/dS black string. By analyzing the free energy,
we also found that the stable rotating black string is bigger than the
non-rotating one.
|
[
{
"created": "Thu, 21 Mar 2019 02:35:29 GMT",
"version": "v1"
},
{
"created": "Sat, 30 Mar 2019 08:15:42 GMT",
"version": "v2"
},
{
"created": "Thu, 27 Feb 2020 15:32:47 GMT",
"version": "v3"
},
{
"created": "Wed, 3 Jun 2020 06:03:19 GMT",
"version": "v4"
}
] |
2020-06-04
|
[
[
"Ghosh",
"Sushant G.",
""
],
[
"Kumar",
"Rahul",
""
],
[
"Tannukij",
"Lunchakorn",
""
],
[
"Wongjun",
"Pitayuth",
""
]
] |
One of the solutions of Einstein field equation with cylindrical symmetry is known as black string solution. In this work, the rotating black string solution in dRGT massive gravity is obtained and then called rotating-dRGT black string solution. This solution is a kind of generalized version of rotating AdS/dS black sting solution containing an additional two more terms characterizing the structure of graviton mass. The horizon structures of the black string are explored. The thermodynamical properties of the black string are investigated. We found that it is possible to obtain the Hawking-Page phase transition depending on the additional structure of the graviton mass, while it is not possible for rotating-AdS/dS black string. By analyzing the free energy, we also found that the stable rotating black string is bigger than the non-rotating one.
|
gr-qc/0205046
|
Kudoh Hideaki
|
Hideaki Kudoh
|
Gravity beyond linear perturbations in the braneworld
|
12 pages, typos corrected, Proceedings for YITP workshop "Braneworld
-Dynamics of spacetime boundary -"
|
Prog.Theor.Phys.Suppl.148:145-157,2003
|
10.1143/PTPS.148.145
|
KUNS-1787
|
gr-qc
| null |
In the present paper, we briefly review recent studies of second-order
gravitational perturbations in braneworld models. After we consider the
possibility of pathological behavior of gravity at higher orders of
perturbation, second-order perturbations are discussed in Randall-Sundrum
braneworld models. Because the mass spectra in these braneworld models are
different, we analyze them using different approaches. In the respective
models, it is discussed that 4D Einstein gravity is approximately recovered at
level of second-order perturbation, although there are some exceptional cases
in the two-brane model.
|
[
{
"created": "Sun, 12 May 2002 14:02:17 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Feb 2003 15:20:21 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Kudoh",
"Hideaki",
""
]
] |
In the present paper, we briefly review recent studies of second-order gravitational perturbations in braneworld models. After we consider the possibility of pathological behavior of gravity at higher orders of perturbation, second-order perturbations are discussed in Randall-Sundrum braneworld models. Because the mass spectra in these braneworld models are different, we analyze them using different approaches. In the respective models, it is discussed that 4D Einstein gravity is approximately recovered at level of second-order perturbation, although there are some exceptional cases in the two-brane model.
|
gr-qc/0505133
|
Alan D. Rendall
|
Alan D. Rendall
|
Theorems on existence and global dynamics for the Einstein equations
|
Submitted to Living Reviews in Relativity, major update of Living
Rev. Rel. 5 (2002) 6
|
LivingRev.Rel.8:6,2002
|
10.12942/lrr-2005-6
|
AEI-2005-106
|
gr-qc
| null |
This article is a guide to theorems on existence and global dynamics of
solutions of the Einstein equations. It draws attention to open questions in
the field. The local-in-time Cauchy problem, which is relatively well
understood, is surveyed. Global results for solutions with various types of
symmetry are discussed. A selection of results from Newtonian theory and
special relativity that offer useful comparisons is presented. Treatments of
global results in the case of small data and results on constructing spacetimes
with prescribed singularity structure or late-time asymptotics are given. A
conjectural picture of the asymptotic behaviour of general cosmological
solutions of the Einstein equations is built up. Some miscellaneous topics
connected with the main theme are collected in a separate section.
|
[
{
"created": "Thu, 26 May 2005 09:42:26 GMT",
"version": "v1"
}
] |
2015-06-25
|
[
[
"Rendall",
"Alan D.",
""
]
] |
This article is a guide to theorems on existence and global dynamics of solutions of the Einstein equations. It draws attention to open questions in the field. The local-in-time Cauchy problem, which is relatively well understood, is surveyed. Global results for solutions with various types of symmetry are discussed. A selection of results from Newtonian theory and special relativity that offer useful comparisons is presented. Treatments of global results in the case of small data and results on constructing spacetimes with prescribed singularity structure or late-time asymptotics are given. A conjectural picture of the asymptotic behaviour of general cosmological solutions of the Einstein equations is built up. Some miscellaneous topics connected with the main theme are collected in a separate section.
|
1902.00783
|
Nidal Chamoun
|
A. Ashour (Damascus Univ.), M. Alcheikh (Damascus Univ.) and N.
Chamoun (HIAST)
|
General Modified Friedmann Equations in Rainbow Flat Universe, by
Thermodynamics
|
7 pages, to appear in EPJC
| null |
10.1140/epjc/s10052-019-6640-8
| null |
gr-qc hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the derivation of Friedmann equations in Rainbow gravity
following Jacobson thermodynamic approach. We do not restrict the rainbow
functions to be constant as is customarily used, and show that the first law of
thermodynamics with a corresponding `classical' proportionality between entropy
and surface area, supplemented eventually by a `quantum' logarithmic
correction, are not in general sufficient to obtain the equations in flat FRW
metrics.
|
[
{
"created": "Sat, 2 Feb 2019 20:37:37 GMT",
"version": "v1"
}
] |
2020-05-28
|
[
[
"Ashour",
"A.",
"",
"Damascus Univ."
],
[
"Alcheikh",
"M.",
"",
"Damascus Univ."
],
[
"Chamoun",
"N.",
"",
"HIAST"
]
] |
We investigate the derivation of Friedmann equations in Rainbow gravity following Jacobson thermodynamic approach. We do not restrict the rainbow functions to be constant as is customarily used, and show that the first law of thermodynamics with a corresponding `classical' proportionality between entropy and surface area, supplemented eventually by a `quantum' logarithmic correction, are not in general sufficient to obtain the equations in flat FRW metrics.
|
2112.13266
|
Igor Khavkine
|
Markus B. Fr\"ob, Igor Khavkine, Tom\'a\v{s} M\'alek, Vojt\v{e}ch
Pravda
|
On well-posedness and algebraic type of the five-dimensional charged
rotating black hole with two equal-magnitude angular momenta
|
v2: 26 pages, 1 figure, close to published version
|
Eur. Phys. J. C 82, 215 (2022)
|
10.1140/epjc/s10052-022-10160-z
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
We study various mathematical aspects of the charged rotating black hole with
two equal-magnitude angular momenta in five dimensions. We introduce a
coordinate system that is regular on the horizon and in which Einstein-Maxwell
equations reduce to an autonomous system of ODEs. Employing Bondi and
Kruskal-like coordinates, we analyze the geometric regularity of the black hole
metric at infinity and the horizon, respectively, and the well-posedness of the
corresponding boundary value problem.
We also study the algebraic types of the electromagnetic and curvature
tensors. While outside the horizon the electromagnetic and Ricci tensors are of
type D, the Weyl tensor is algebraically general. The Weyl tensor simplifies to
type~II on the horizon and type~D on the bifurcation sphere. These results
imply inconsistency of the metric with the Kerr--Schild form with a geodesic
Kerr-Schild vector. This feature is shared by the four-dimensional Kerr-Newman
metric and the vacuum Myers-Perry or charged Schwarzschild-Tangherlini
geometries in arbitrary dimension, but hence not by the black hole we have
considered here.
|
[
{
"created": "Sat, 25 Dec 2021 18:38:47 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Mar 2022 11:39:56 GMT",
"version": "v2"
}
] |
2022-03-14
|
[
[
"Fröb",
"Markus B.",
""
],
[
"Khavkine",
"Igor",
""
],
[
"Málek",
"Tomáš",
""
],
[
"Pravda",
"Vojtěch",
""
]
] |
We study various mathematical aspects of the charged rotating black hole with two equal-magnitude angular momenta in five dimensions. We introduce a coordinate system that is regular on the horizon and in which Einstein-Maxwell equations reduce to an autonomous system of ODEs. Employing Bondi and Kruskal-like coordinates, we analyze the geometric regularity of the black hole metric at infinity and the horizon, respectively, and the well-posedness of the corresponding boundary value problem. We also study the algebraic types of the electromagnetic and curvature tensors. While outside the horizon the electromagnetic and Ricci tensors are of type D, the Weyl tensor is algebraically general. The Weyl tensor simplifies to type~II on the horizon and type~D on the bifurcation sphere. These results imply inconsistency of the metric with the Kerr--Schild form with a geodesic Kerr-Schild vector. This feature is shared by the four-dimensional Kerr-Newman metric and the vacuum Myers-Perry or charged Schwarzschild-Tangherlini geometries in arbitrary dimension, but hence not by the black hole we have considered here.
|
gr-qc/9310023
| null |
R. Brout and Ph. Spindel
|
Entropy Production from Vacuum Decay
|
UMH-ULB-TH 05/93
|
Phys.Lett. B320 (1994) 241-244
|
10.1016/0370-2693(94)90651-3
| null |
gr-qc
| null |
Using as dynamical variable the square of the radius of the Universe, we
solve analytically the Einstein equations in the framework of Robertson-Walker
models where a cosmological constant describing phenomenologically the vacuum
energy decays into radiation. Emphasis is put on the computation of the entropy
creation.
|
[
{
"created": "Fri, 15 Oct 1993 10:41:07 GMT",
"version": "v1"
}
] |
2009-10-22
|
[
[
"Brout",
"R.",
""
],
[
"Spindel",
"Ph.",
""
]
] |
Using as dynamical variable the square of the radius of the Universe, we solve analytically the Einstein equations in the framework of Robertson-Walker models where a cosmological constant describing phenomenologically the vacuum energy decays into radiation. Emphasis is put on the computation of the entropy creation.
|
1105.5391
|
Helvi Witek
|
Ulrich Sperhake, Vitor Cardoso, Christian D. Ott, Erik Schnetter and
Helvi Witek
|
Extreme black hole simulations: collisions of unequal mass black holes
and the point particle limit
|
7 pages, 2 pages
| null |
10.1103/PhysRevD.84.084038
| null |
gr-qc astro-ph.HE hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Numerical relativity has seen incredible progress in the last years, and is
being applied with success to a variety of physical phenomena, from
gravitational-wave research and relativistic astrophysics to cosmology and
high-energy physics. Here we probe the limits of current numerical setups, by
studying collisions of unequal mass, non-rotating black holes of mass-ratios up
to 1:100 and making contact with a classical calculation in General Relativity:
the infall of a point-like particle into a massive black hole.
Our results agree well with the predictions coming from linearized
calculations of the infall of point-like particles into non-rotating black
holes. In particular, in the limit that one hole is much smaller than the
other, and the infall starts from an infinite initial separation, we recover
the point-particle limit. Thus, numerical relativity is able to bridge the gap
between fully non-linear dynamics and linearized approximations, which may have
important applications. Finally, we also comment on the "spurious" radiation
content in the initial data and the linearized predictions.
|
[
{
"created": "Thu, 26 May 2011 20:01:18 GMT",
"version": "v1"
}
] |
2013-05-29
|
[
[
"Sperhake",
"Ulrich",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Ott",
"Christian D.",
""
],
[
"Schnetter",
"Erik",
""
],
[
"Witek",
"Helvi",
""
]
] |
Numerical relativity has seen incredible progress in the last years, and is being applied with success to a variety of physical phenomena, from gravitational-wave research and relativistic astrophysics to cosmology and high-energy physics. Here we probe the limits of current numerical setups, by studying collisions of unequal mass, non-rotating black holes of mass-ratios up to 1:100 and making contact with a classical calculation in General Relativity: the infall of a point-like particle into a massive black hole. Our results agree well with the predictions coming from linearized calculations of the infall of point-like particles into non-rotating black holes. In particular, in the limit that one hole is much smaller than the other, and the infall starts from an infinite initial separation, we recover the point-particle limit. Thus, numerical relativity is able to bridge the gap between fully non-linear dynamics and linearized approximations, which may have important applications. Finally, we also comment on the "spurious" radiation content in the initial data and the linearized predictions.
|
1110.3114
|
Abril Su\'arez
|
T. Matos and A. Su\'arez
|
Finite temperature and dissipative corrections to the Gross-Pitaevskii
equation from $\lambda\Phi^4$ one loop contributions
|
5 pages, accepted for publication at EPL. arXiv admin note:
substantial text overlap with arXiv:1103.5731
|
T. Matos and A. Su\'arez 2011 EPL 96 56005
|
10.1209/0295-5075/96/56005
| null |
gr-qc cond-mat.quant-gas
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Starting with a scalar field in a thermal bath and using the one loop quantum
correction potential, we rewrite the Klein-Gordon equation in its
thermodynamical representation and study the behavior of this scalar field due
to temperature variations in the equations of motion. We find the
generalization of a Gross-Pitaevskii like equation for a relativistic Bose gas
with finite temperature, the corresponding thermodynamic and viscosity
expressions, and an expression for the postulate of the first law of the
thermodynamics for this BECs. We also propose that the equations obtained might
help to explain at some level the phase transition of a Bose-Einstein
Condensate in terms of quantum field theory in a simple way.
|
[
{
"created": "Fri, 14 Oct 2011 02:43:24 GMT",
"version": "v1"
}
] |
2014-02-04
|
[
[
"Matos",
"T.",
""
],
[
"Suárez",
"A.",
""
]
] |
Starting with a scalar field in a thermal bath and using the one loop quantum correction potential, we rewrite the Klein-Gordon equation in its thermodynamical representation and study the behavior of this scalar field due to temperature variations in the equations of motion. We find the generalization of a Gross-Pitaevskii like equation for a relativistic Bose gas with finite temperature, the corresponding thermodynamic and viscosity expressions, and an expression for the postulate of the first law of the thermodynamics for this BECs. We also propose that the equations obtained might help to explain at some level the phase transition of a Bose-Einstein Condensate in terms of quantum field theory in a simple way.
|
1407.7119
|
Hristu Culetu
|
Hristu Culetu
|
On the Vaz no horizon black hole
|
7 pages, no figures, minor changes, reference added
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We propose a no horizon black hole whose collapsing matter condenses close to
the event horizon and before its formation. Compared to Vaz's model [arXiv:
1407.3823], our interior geometry depends only on one parameter $r_{0}$ - the
radius of the region where quantum fluctuations are significant. While the
equation of state of the inner fluid is $p_{r} = -\rho$ and the traverse
pressures are vanishing, the surface stress tensor corresponds to an
anisotropic fluid with negative surface tension. Using the junction conditions
on the boundary of the collapsing star, we found that $r_{0}$ is half its
Schwarzschild radius and not $2M$, as previously obtained by Vaz for a dust
ball.
|
[
{
"created": "Sat, 26 Jul 2014 10:35:39 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Aug 2014 12:08:27 GMT",
"version": "v2"
}
] |
2014-08-04
|
[
[
"Culetu",
"Hristu",
""
]
] |
We propose a no horizon black hole whose collapsing matter condenses close to the event horizon and before its formation. Compared to Vaz's model [arXiv: 1407.3823], our interior geometry depends only on one parameter $r_{0}$ - the radius of the region where quantum fluctuations are significant. While the equation of state of the inner fluid is $p_{r} = -\rho$ and the traverse pressures are vanishing, the surface stress tensor corresponds to an anisotropic fluid with negative surface tension. Using the junction conditions on the boundary of the collapsing star, we found that $r_{0}$ is half its Schwarzschild radius and not $2M$, as previously obtained by Vaz for a dust ball.
|
0801.3497
|
Allan Joseph Michael Medved
|
A.J.M. Medved
|
A Commentary on Ruppeiner Metrics for Black Holes
|
15 pages; v2, typos corrected and a few references added
|
Mod.Phys.Lett.A23:2149-2161,2008
|
10.1142/S0217732308027333
| null |
gr-qc
| null |
There has been some recent controversy regarding the Ruppeiner metrics that
are induced by Reissner-Nordstrom (and Reissner-Nordstrom-like) black holes.
Most infamously, why does this family of metrics turn out to be flat, how is
this outcome to be physically understood, and can/should the formalism be
suitably modified to induce curvature? In the current paper, we provide a novel
interpretation of this debate. For the sake of maximal analytic clarity and
tractability, some supporting calculations are carried out for the relatively
simple model of a rotating BTZ black hole.
|
[
{
"created": "Wed, 23 Jan 2008 20:55:44 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Jan 2008 09:36:22 GMT",
"version": "v2"
}
] |
2008-12-18
|
[
[
"Medved",
"A. J. M.",
""
]
] |
There has been some recent controversy regarding the Ruppeiner metrics that are induced by Reissner-Nordstrom (and Reissner-Nordstrom-like) black holes. Most infamously, why does this family of metrics turn out to be flat, how is this outcome to be physically understood, and can/should the formalism be suitably modified to induce curvature? In the current paper, we provide a novel interpretation of this debate. For the sake of maximal analytic clarity and tractability, some supporting calculations are carried out for the relatively simple model of a rotating BTZ black hole.
|
gr-qc/9806041
|
Alejandro Corichi
|
Abhay Ashtekar, Alejandro Corichi and Jose. A. Zapata
|
Quantum Theory of Geometry III: Non-commutativity of Riemannian
Structures
|
20 pages, revtex, 1 figure. Some typos corrected. References updated
|
Class.Quant.Grav. 15 (1998) 2955-2972
|
10.1088/0264-9381/15/10/006
|
CGPG-98/6-1
|
gr-qc hep-th
| null |
The basic framework for a systematic construction of a quantum theory of
Riemannian geometry was introduced recently. The quantum versions of Riemannian
structures --such as triad and area operators-- exhibit a non-commutativity. At
first sight, this feature is surprising because it implies that the framework
does not admit a triad representation. To better understand this property and
to reconcile it with intuition, we analyze its origin in detail. In particular,
a careful study of the underlying phase space is made and the feature is traced
back to the classical theory; there is no anomaly associated with quantization.
We also indicate why the uncertainties associated with this non-commutativity
become negligible in the semi-classical regime.
|
[
{
"created": "Tue, 9 Jun 1998 06:01:31 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Aug 1998 22:07:03 GMT",
"version": "v2"
}
] |
2009-10-31
|
[
[
"Ashtekar",
"Abhay",
""
],
[
"Corichi",
"Alejandro",
""
],
[
"Zapata",
"Jose. A.",
""
]
] |
The basic framework for a systematic construction of a quantum theory of Riemannian geometry was introduced recently. The quantum versions of Riemannian structures --such as triad and area operators-- exhibit a non-commutativity. At first sight, this feature is surprising because it implies that the framework does not admit a triad representation. To better understand this property and to reconcile it with intuition, we analyze its origin in detail. In particular, a careful study of the underlying phase space is made and the feature is traced back to the classical theory; there is no anomaly associated with quantization. We also indicate why the uncertainties associated with this non-commutativity become negligible in the semi-classical regime.
|
1408.3691
|
Erik Curiel
|
Erik Curiel
|
Classical Black Holes Are Hot
|
30 pages; revised so as to address possible counter-example due to
Bob Wald, that treating black holes purely classically may lead to violations
of the GSL
| null | null | null |
gr-qc physics.hist-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In the early 1970s it is was realized that there is a striking formal analogy
between the Laws of black-hole mechanics and the Laws of classical
thermodynamics. Before the discovery of Hawking radiation, however, it was
generally thought that the analogy was only formal, and did not reflect a deep
connection between gravitational and thermodynamical phenomena. It is still
commonly held that the surface gravity of a stationary black hole can be
construed as a true physical temperature and its area as a true entropy only
when quantum effects are taken into account; in the context of classical
general relativity alone, one cannot cogently construe them so. Does the use of
quantum field theory in curved spacetime offer the only hope for taking the
analogy seriously? I think the answer is `no'. To attempt to justify that
answer, I shall begin by arguing that the standard argument to the contrary is
not physically well founded, and in any event begs the question. Looking at the
various ways that the ideas of "temperature" and "entropy" enter classical
thermodynamics then will suggest arguments that, I claim, show the analogy
between classical black-hole mechanics and classical thermodynamics should be
taken more seriously, without the need to rely on or invoke quantum mechanics.
In particular, I construct an analogue of a Carnot cycle in which a black hole
"couples" with an ordinary thermodynamical system in such a way that its
surface gravity plays the role of temperature and its area that of entropy.
Thus, the connection between classical general relativity and classical
thermodynamics on their own is already deep and physically significant,
independent of quantum mechanics.
|
[
{
"created": "Sat, 16 Aug 2014 01:14:38 GMT",
"version": "v1"
},
{
"created": "Sun, 9 Nov 2014 20:04:41 GMT",
"version": "v2"
}
] |
2014-11-11
|
[
[
"Curiel",
"Erik",
""
]
] |
In the early 1970s it is was realized that there is a striking formal analogy between the Laws of black-hole mechanics and the Laws of classical thermodynamics. Before the discovery of Hawking radiation, however, it was generally thought that the analogy was only formal, and did not reflect a deep connection between gravitational and thermodynamical phenomena. It is still commonly held that the surface gravity of a stationary black hole can be construed as a true physical temperature and its area as a true entropy only when quantum effects are taken into account; in the context of classical general relativity alone, one cannot cogently construe them so. Does the use of quantum field theory in curved spacetime offer the only hope for taking the analogy seriously? I think the answer is `no'. To attempt to justify that answer, I shall begin by arguing that the standard argument to the contrary is not physically well founded, and in any event begs the question. Looking at the various ways that the ideas of "temperature" and "entropy" enter classical thermodynamics then will suggest arguments that, I claim, show the analogy between classical black-hole mechanics and classical thermodynamics should be taken more seriously, without the need to rely on or invoke quantum mechanics. In particular, I construct an analogue of a Carnot cycle in which a black hole "couples" with an ordinary thermodynamical system in such a way that its surface gravity plays the role of temperature and its area that of entropy. Thus, the connection between classical general relativity and classical thermodynamics on their own is already deep and physically significant, independent of quantum mechanics.
|
gr-qc/0404122
|
Luca Lusanna
|
Luca Lusanna (INFN, Firenze)
|
The Chrono'Geometrical Structure of Special and General Relativity:
Towards a Background-Independent Description of the Gravitational Field and
Elementary Particles
|
71 pages, invited paper for the book "Progress in General Relativity
and Quantum Cosmology Research" (Nova Science)
| null | null | null |
gr-qc astro-ph hep-th
| null |
Since the main open problem of contemporary physics is to find a unified
description of the four interactions, we present a possible scenario which,
till now only at the classical level, is able to englobe experiments ranging
from experimental space gravitation to atomic and particle physics. After a
reformulation of special relativistic physics in a form taking into account the
non-dynamical chrono-geometrical structure of Minkowski space-time
(parametrized Minkowski theories and rest-frame instant form) and in particular
the conventionality of simultaneity (re-phrased as a gauge freedom), a model of
canonical metric and tetrad gravity is proposed in a class of space-times where
the deparametrization to Minkowski space-time is possible. In them it is
possible to give a post-Minkowskian background-independent description of the
gravitational field and of matter. The study of the dynamical
chrono-geometrical structure of these space-times allows to face
interpretational problems like the physical identification of point-events (the
Hole Argument), the distinction between inertial (gauge) and tidal (Dirac
observables) effects, the dynamical nature of simultaneity in general
relativity and to find background-independent gravitational waves. These
developments are possible at the Hamiltonian level due to a systematic use of
Dirac-Bergmann theory of constraints. Finally there is a proposal for a new
coordinate- and background-independent quantization scheme for gravity.
|
[
{
"created": "Thu, 29 Apr 2004 09:10:21 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Lusanna",
"Luca",
"",
"INFN, Firenze"
]
] |
Since the main open problem of contemporary physics is to find a unified description of the four interactions, we present a possible scenario which, till now only at the classical level, is able to englobe experiments ranging from experimental space gravitation to atomic and particle physics. After a reformulation of special relativistic physics in a form taking into account the non-dynamical chrono-geometrical structure of Minkowski space-time (parametrized Minkowski theories and rest-frame instant form) and in particular the conventionality of simultaneity (re-phrased as a gauge freedom), a model of canonical metric and tetrad gravity is proposed in a class of space-times where the deparametrization to Minkowski space-time is possible. In them it is possible to give a post-Minkowskian background-independent description of the gravitational field and of matter. The study of the dynamical chrono-geometrical structure of these space-times allows to face interpretational problems like the physical identification of point-events (the Hole Argument), the distinction between inertial (gauge) and tidal (Dirac observables) effects, the dynamical nature of simultaneity in general relativity and to find background-independent gravitational waves. These developments are possible at the Hamiltonian level due to a systematic use of Dirac-Bergmann theory of constraints. Finally there is a proposal for a new coordinate- and background-independent quantization scheme for gravity.
|
1903.09037
|
Jos\'e Villanueva
|
Mohsen Fathi, \'Angel Rinc\'on and J.R. Villanueva
|
Photons trajectories on a first order scale-dependent static BTZ black
hole
|
9 pages, 6 figures
| null |
10.1088/1361-6382/ab6f7c
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we study the motion of massless particles on a static BTZ black
hole background in the context of scale-dependent gravity, which is
characterized by the running parameter $\epsilon$. Thus, by using standard
methods we obtain the equation of motions and then analytic solutions are
found. The relevant non-trivial differences appear when we compare our solution
against the classical counterpart.
|
[
{
"created": "Thu, 21 Mar 2019 14:53:23 GMT",
"version": "v1"
}
] |
2020-04-08
|
[
[
"Fathi",
"Mohsen",
""
],
[
"Rincón",
"Ángel",
""
],
[
"Villanueva",
"J. R.",
""
]
] |
In this paper we study the motion of massless particles on a static BTZ black hole background in the context of scale-dependent gravity, which is characterized by the running parameter $\epsilon$. Thus, by using standard methods we obtain the equation of motions and then analytic solutions are found. The relevant non-trivial differences appear when we compare our solution against the classical counterpart.
|
2005.14114
|
Karan Fernandes
|
Karan Fernandes, Susovan Maity and Tapas K. Das
|
Emergent gravity through non-linear perturbation
|
The analysis concerned the specific case of Bondi flows, but holds in
a more general setting. The revised general analysis including the high and
low frequency perturbation results lie beyond the scope of a replacement
| null | null | null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
As of now, all analogue gravity models available in the literature deal with
the emergence of an acoustic geometry through linear perturbations of transonic
fluids only. It has never been investigated whether the analogue gravity
phenomena is solely a consequence of linear perturbations, or rather a generic
property of arbitrary perturbations of inhomogeneous, inviscid and irrotational
fluids. In the present work, for the first time in the literature, we
demonstrate that acoustic spacetimes may be formed through higher order
non-linear perturbations, and thus establish that analogue gravity phenomena is
rather more general than what was thought before. We consider spherically
accreting astrophysical systems as a natural classical analogue gravity model,
and develop a formalism to investigate non-linear perturbations of such
accretion flows to arbitrary order. Our iterative approach involves a coupled
set of equations for the mass accretion rate and the density of the fluid. In
particular, we demonstrate that the wave equation for the mass accretion rate
involves an acoustic metric which can be perturbatively constructed to all
orders. We numerically solve the coupled equations about the leading transonic
Bondi flow solution. This analysis uses boundary conditions set to the original
unperturbed values, with the time dependence of the mass accretion rate
perturbation taken to be exponentially damped. The perturbed solutions indicate
that second order and higher perturbations of the metric generically cause the
original acoustic horizon to oscillate and change in size. We explain this
phenomenon in detail and its implications on non-linear perturbations of
accretion flows in general.
|
[
{
"created": "Thu, 28 May 2020 16:08:58 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Jun 2021 05:16:58 GMT",
"version": "v2"
}
] |
2021-06-08
|
[
[
"Fernandes",
"Karan",
""
],
[
"Maity",
"Susovan",
""
],
[
"Das",
"Tapas K.",
""
]
] |
As of now, all analogue gravity models available in the literature deal with the emergence of an acoustic geometry through linear perturbations of transonic fluids only. It has never been investigated whether the analogue gravity phenomena is solely a consequence of linear perturbations, or rather a generic property of arbitrary perturbations of inhomogeneous, inviscid and irrotational fluids. In the present work, for the first time in the literature, we demonstrate that acoustic spacetimes may be formed through higher order non-linear perturbations, and thus establish that analogue gravity phenomena is rather more general than what was thought before. We consider spherically accreting astrophysical systems as a natural classical analogue gravity model, and develop a formalism to investigate non-linear perturbations of such accretion flows to arbitrary order. Our iterative approach involves a coupled set of equations for the mass accretion rate and the density of the fluid. In particular, we demonstrate that the wave equation for the mass accretion rate involves an acoustic metric which can be perturbatively constructed to all orders. We numerically solve the coupled equations about the leading transonic Bondi flow solution. This analysis uses boundary conditions set to the original unperturbed values, with the time dependence of the mass accretion rate perturbation taken to be exponentially damped. The perturbed solutions indicate that second order and higher perturbations of the metric generically cause the original acoustic horizon to oscillate and change in size. We explain this phenomenon in detail and its implications on non-linear perturbations of accretion flows in general.
|
gr-qc/0410111
|
Gianluca Calcagni
|
Gianluca Calcagni
|
Regularized dualities in patch cosmology
|
5 pages, 1 figure
| null | null |
UPRF-2004-26
|
gr-qc astro-ph hep-th
| null |
Following past investigations, we explore the symmetries of the
Hamilton-Jacobi cosmological equations in the generalized patch formalism
describing braneworld and tachyon scenarios. Dualities between different
patches are established and regular dual solutions, either contracting or
phantom-like, are constructed.
|
[
{
"created": "Thu, 21 Oct 2004 15:08:41 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Calcagni",
"Gianluca",
""
]
] |
Following past investigations, we explore the symmetries of the Hamilton-Jacobi cosmological equations in the generalized patch formalism describing braneworld and tachyon scenarios. Dualities between different patches are established and regular dual solutions, either contracting or phantom-like, are constructed.
|
gr-qc/0702124
|
Eirini Messaritaki
|
Eirini Messaritaki
|
The singular field used to calculate the self-force on non-spinning and
spinning particles
|
14 pages; addressed referee's comments; published in PhysRevD
|
Phys.Rev.D75:104011,2007
|
10.1103/PhysRevD.75.104011
| null |
gr-qc
| null |
The singular field of a point charge has recently been described in terms of
a new Green's function of curved spacetime. This singular field plays an
important role in the calculation of the self-force acting upon the particle.
We provide a method for calculating the singular field and a catalog of
expansions of the singular field associated with the geodesic motion of
monopole and dipole sources for scalar, electromagnetic and gravitational
fields. These results can be used, for example, to calculate the effects of the
self-force acting on a particle as it moves through spacetime.
|
[
{
"created": "Fri, 23 Feb 2007 19:04:31 GMT",
"version": "v1"
},
{
"created": "Tue, 15 May 2007 18:16:47 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Messaritaki",
"Eirini",
""
]
] |
The singular field of a point charge has recently been described in terms of a new Green's function of curved spacetime. This singular field plays an important role in the calculation of the self-force acting upon the particle. We provide a method for calculating the singular field and a catalog of expansions of the singular field associated with the geodesic motion of monopole and dipole sources for scalar, electromagnetic and gravitational fields. These results can be used, for example, to calculate the effects of the self-force acting on a particle as it moves through spacetime.
|
0710.2013
|
Shankaranarayanan S
|
Sudipta Sarkar (IUCAA), S. Shankaranarayanan (AEI, Golm), L.
Sriramkumar (HRI, Allahabad)
|
Sub-leading contributions to the black hole entropy in the brick wall
approach
|
21 pages, Revtex 4; Final verson - 22 pages, References added,
Accepted in Phys. Rev. D
|
Phys.Rev.D78:024003,2008
|
10.1103/PhysRevD.78.024003
|
AEI-2007-139
|
gr-qc hep-th
| null |
[Abridged] We compute the canonical entropy of a quantum scalar field around
static and spherically symmetric black holes through the brick wall approach at
the higher orders (in fact, up to the sixth order in \hbar) in the WKB
approximation. We explicitly show that the brick wall model generally predicts
corrections to the Bekenstein-Hawking entropy in all spacetime dimensions. In
four dimensions, we find that the corrections to the Bekenstein-Hawking entropy
are of the form (A^n \log A), while, in six dimensions, the corrections behave
as (A^m + A^n \log A), where A denotes the area of the black hole event
horizon, and (m, n) < 1. We compare our results with the corrections to the
Bekenstein-Hawking entropy that have been obtained through the other approaches
in the literature, and discuss the implications.
|
[
{
"created": "Wed, 10 Oct 2007 13:59:24 GMT",
"version": "v1"
},
{
"created": "Sun, 1 Jun 2008 17:52:54 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Sarkar",
"Sudipta",
"",
"IUCAA"
],
[
"Shankaranarayanan",
"S.",
"",
"AEI, Golm"
],
[
"Sriramkumar",
"L.",
"",
"HRI, Allahabad"
]
] |
[Abridged] We compute the canonical entropy of a quantum scalar field around static and spherically symmetric black holes through the brick wall approach at the higher orders (in fact, up to the sixth order in \hbar) in the WKB approximation. We explicitly show that the brick wall model generally predicts corrections to the Bekenstein-Hawking entropy in all spacetime dimensions. In four dimensions, we find that the corrections to the Bekenstein-Hawking entropy are of the form (A^n \log A), while, in six dimensions, the corrections behave as (A^m + A^n \log A), where A denotes the area of the black hole event horizon, and (m, n) < 1. We compare our results with the corrections to the Bekenstein-Hawking entropy that have been obtained through the other approaches in the literature, and discuss the implications.
|
gr-qc/9404041
|
Jose Pizarro de Sande Lemos
|
Jose' P. S. Lemos
|
Cylindrical Black Hole in General Relativity
| null |
Phys.Lett.B353:46-51,1995
|
10.1016/0370-2693(95)00533-Q
| null |
gr-qc
| null |
A black hole solution of Einstein's field equations with cylindrical symmetry
is found. Using the Hamiltonian formulation one is able to define mass and
angular momentum for the cylindrical black hole through the corresponding and
equivalent three dimensional theory. The causal structure is analyzed.
Comments: revised version.
|
[
{
"created": "Sat, 23 Apr 1994 00:40:06 GMT",
"version": "v1"
},
{
"created": "Wed, 17 May 1995 01:05:44 GMT",
"version": "v2"
}
] |
2010-11-01
|
[
[
"Lemos",
"Jose' P. S.",
""
]
] |
A black hole solution of Einstein's field equations with cylindrical symmetry is found. Using the Hamiltonian formulation one is able to define mass and angular momentum for the cylindrical black hole through the corresponding and equivalent three dimensional theory. The causal structure is analyzed. Comments: revised version.
|
gr-qc/9906094
|
S. Antoci
|
S. Antoci and L. Mihich
|
A four-dimensional Hooke's law can encompass linear elasticity and
inertia
|
AMS LaTeX, 8 pages, Nuovo Cimento B (in press)
|
Nuovo Cim. B114 (1999) 873
| null | null |
gr-qc
| null |
The question is examined, whether the formally straightforward extension of
Hooke's time-honoured stress-strain relation to the four dimensions of special
and of general relativity can make physical sense. The four-dimensional Hooke's
law is found able to account for the inertia of matter; in the flat space, slow
motion approximation the field equations for the ``displacement'' four-vector
field can encompass both linear elasticity and inertia. In this limit one just
recovers the equations of motion of the classical theory of elasticity.
|
[
{
"created": "Wed, 23 Jun 1999 14:53:10 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Antoci",
"S.",
""
],
[
"Mihich",
"L.",
""
]
] |
The question is examined, whether the formally straightforward extension of Hooke's time-honoured stress-strain relation to the four dimensions of special and of general relativity can make physical sense. The four-dimensional Hooke's law is found able to account for the inertia of matter; in the flat space, slow motion approximation the field equations for the ``displacement'' four-vector field can encompass both linear elasticity and inertia. In this limit one just recovers the equations of motion of the classical theory of elasticity.
|
gr-qc/0303027
|
Jorge Pullin
|
Jorge Pullin
|
Matters of Gravity, the newsletter of the APS Topical Group on
Gravitation, Spring 2003
|
28 pages, LaTeX with html.sty and psfig, 4 figures. Jorge Pullin
(editor). PDF and html versions in http://www.phys.lsu.edu/mog
| null | null |
MOG-21
|
gr-qc
| null |
Contents:
* Community news:
GGR activities, by Richard Price
We hear that..., by Jorge Pullin
Institute of Physics Gravitational Physics Group, by Elizabeth Winstanley
Center for gravitational wave astronomy, by Mario Diaz
* Research briefs:
LIGO's first preliminary science run, by Gary Sanders
Quantization of area: the plot thickens, by John Baez
Convergence of G measurements -Mysteries remain, by Riley Newman
* Conference reports:
Brane world gravity, by Elizabeth Winstanley
Massive black holes focus session, by Steinn Sigurdsson
GWDAW 2002, by Peter Saulson
Source simulation focus session, by Pablo Laguna
RRI workshop on loop quantum gravity, by Fernando Barbero
Lazarus/Kudu Meeting, by Warren G. Anderson
|
[
{
"created": "Thu, 6 Mar 2003 23:06:16 GMT",
"version": "v1"
}
] |
2009-03-10
|
[
[
"Pullin",
"Jorge",
""
]
] |
Contents: * Community news: GGR activities, by Richard Price We hear that..., by Jorge Pullin Institute of Physics Gravitational Physics Group, by Elizabeth Winstanley Center for gravitational wave astronomy, by Mario Diaz * Research briefs: LIGO's first preliminary science run, by Gary Sanders Quantization of area: the plot thickens, by John Baez Convergence of G measurements -Mysteries remain, by Riley Newman * Conference reports: Brane world gravity, by Elizabeth Winstanley Massive black holes focus session, by Steinn Sigurdsson GWDAW 2002, by Peter Saulson Source simulation focus session, by Pablo Laguna RRI workshop on loop quantum gravity, by Fernando Barbero Lazarus/Kudu Meeting, by Warren G. Anderson
|
2010.00008
|
Miguel Zilhao
|
Taishi Ikeda, Laura Bernard, Vitor Cardoso, Miguel Zilhao
|
Black hole binaries and light fields: Gravitational molecules
|
16 pages, 12 figures. Matches published version in PRD
|
Phys. Rev. D 103, 024020 (2021)
|
10.1103/PhysRevD.103.024020
| null |
gr-qc astro-ph.HE hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We show that light scalars can form quasibound states around binaries. In the
nonrelativistic regime, these states are formally described by the
quantum-mechanical Schrodinger equation for a one-electron heteronuclear
diatomic molecule. We performed extensive numerical simulations of scalar
fields around black hole binaries showing that a scalar structure condenses
around the binary -- we dub these states "gravitational molecules". We further
show that these are well described by the perturbative, nonrelativistic
description.
|
[
{
"created": "Wed, 30 Sep 2020 18:00:00 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Jan 2021 15:27:59 GMT",
"version": "v2"
}
] |
2021-01-13
|
[
[
"Ikeda",
"Taishi",
""
],
[
"Bernard",
"Laura",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Zilhao",
"Miguel",
""
]
] |
We show that light scalars can form quasibound states around binaries. In the nonrelativistic regime, these states are formally described by the quantum-mechanical Schrodinger equation for a one-electron heteronuclear diatomic molecule. We performed extensive numerical simulations of scalar fields around black hole binaries showing that a scalar structure condenses around the binary -- we dub these states "gravitational molecules". We further show that these are well described by the perturbative, nonrelativistic description.
|
gr-qc/0008009
|
Antonio Alfonso Faus
|
Antonio Alfonso-Faus
|
The Speed of Light and the Fine Structure Constant
|
4 pages. ReVTeX Some minor corrections
|
Phys.Essays 13:46-49,2000
|
10.4006/1.3025=
| null |
gr-qc
| null |
The fine structure constant $\alpha $ includes the speed of light as given by
$\alpha =\frac{e^{2}}{4\pi \epsilon_{0}c\hbar}$. It is shown here that,
following a $TH\epsilon \mu $ formalism, interpreting the permittivity
$\epsilon_{0}$ and permeabiliy $\mu_{0}$ of free space under Lorentz local and
position invariance, this is not the case. The result is a new expression as
$\alpha =\frac{e^{2}}{4\pi \hbar}$ in a new system of units for the charge that
preserves local and position invariance. Hence, the speed of light does not
explicitly enter in the constitution of the fine structure constant. The new
expressions for the Maxwell's equations are derived and some cosmological
implications discussed.
|
[
{
"created": "Fri, 4 Aug 2000 09:17:06 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Aug 2000 09:17:20 GMT",
"version": "v2"
}
] |
2009-08-25
|
[
[
"Alfonso-Faus",
"Antonio",
""
]
] |
The fine structure constant $\alpha $ includes the speed of light as given by $\alpha =\frac{e^{2}}{4\pi \epsilon_{0}c\hbar}$. It is shown here that, following a $TH\epsilon \mu $ formalism, interpreting the permittivity $\epsilon_{0}$ and permeabiliy $\mu_{0}$ of free space under Lorentz local and position invariance, this is not the case. The result is a new expression as $\alpha =\frac{e^{2}}{4\pi \hbar}$ in a new system of units for the charge that preserves local and position invariance. Hence, the speed of light does not explicitly enter in the constitution of the fine structure constant. The new expressions for the Maxwell's equations are derived and some cosmological implications discussed.
|
2312.14071
|
Robert Bluhm
|
Robert Bluhm and Yu Zhi
|
Spontaneous and Explicit Spacetime Symmetry Breaking in Einstein-Cartan
Theory with Background Fields
|
27 pages
|
Symmetry 16 (2024) 25
|
10.3390/sym16010025
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Explicit and spontaneous breaking of spacetime symmetry under
diffeomorphisms, local translations, and local Lorentz transformations due to
the presence of fixed background fields is examined in Einstein-Cartan theory.
In particular, the roles of torsion and violation of local translation
invariance are highlighted. The nature of the types of background fields that
can arise and how they cause spacetime symmetry breaking is discussed. With
explicit breaking, potential no-go results are known to exist, which if not
evaded lead to inconsistencies between the Bianchi identities, Noether
identities, and the equations of motion. These are examined in detail, and the
effects of nondynamical backgrounds and explicit breaking on the
energy-momentum tensor when torsion is present are discussed as well. Examples
illustrating various features of both explicit and spontaneous breaking of
local translations are presented and compared to the case of diffeomorphism
breaking.
|
[
{
"created": "Thu, 21 Dec 2023 17:49:00 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Jan 2024 16:14:37 GMT",
"version": "v2"
}
] |
2024-01-22
|
[
[
"Bluhm",
"Robert",
""
],
[
"Zhi",
"Yu",
""
]
] |
Explicit and spontaneous breaking of spacetime symmetry under diffeomorphisms, local translations, and local Lorentz transformations due to the presence of fixed background fields is examined in Einstein-Cartan theory. In particular, the roles of torsion and violation of local translation invariance are highlighted. The nature of the types of background fields that can arise and how they cause spacetime symmetry breaking is discussed. With explicit breaking, potential no-go results are known to exist, which if not evaded lead to inconsistencies between the Bianchi identities, Noether identities, and the equations of motion. These are examined in detail, and the effects of nondynamical backgrounds and explicit breaking on the energy-momentum tensor when torsion is present are discussed as well. Examples illustrating various features of both explicit and spontaneous breaking of local translations are presented and compared to the case of diffeomorphism breaking.
|
1801.09186
|
Georgia Kittou
|
Georgia Kittou
|
Is interacting vacuum viable?
|
6 pages
| null |
10.1016/j.physletb.2018.04.059
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the asymptotic dynamics of dark energy as a mixture of pressureless
matter and an interacting vacuum component. We find that the only dynamics
compatible with current observational data favors an asymptotically vanishing
matter-vacuum energy interaction in a model where dark energy is simulated by a
generalized Chaplygin gas cosmology
|
[
{
"created": "Sun, 28 Jan 2018 06:09:25 GMT",
"version": "v1"
},
{
"created": "Sun, 8 Apr 2018 10:50:58 GMT",
"version": "v2"
},
{
"created": "Thu, 19 Apr 2018 19:53:35 GMT",
"version": "v3"
}
] |
2018-09-19
|
[
[
"Kittou",
"Georgia",
""
]
] |
We study the asymptotic dynamics of dark energy as a mixture of pressureless matter and an interacting vacuum component. We find that the only dynamics compatible with current observational data favors an asymptotically vanishing matter-vacuum energy interaction in a model where dark energy is simulated by a generalized Chaplygin gas cosmology
|
1608.08971
|
Julio Cesar Fabris
|
C.R. Almeida, A.B. Batista, J.C. Fabris, P.V. Moniz
|
Quantum cosmology of scalar-tensor theories and self-adjointness
|
Latex file, 12 pages. Small changes made in the paper, and a a new
appendix added
| null |
10.1063/1.4979537
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, the problem of the self-adjointness for the case of a quantum
minisuperspace Hamiltonian retrieved from a Brans-Dicke (BD) action is
investigated. Our matter content is presented in terms of a perfect fluid, onto
which the Schutz's formalism will be applied. We use the von Neumann theorem
and the similarity with the Laplacian operator in one of the variables to
determine the cases where the Hamiltonian is self-adjoint and if it admits
self-adjoint extensions. For the latter, we study which extension is physically
more suitable.
|
[
{
"created": "Wed, 31 Aug 2016 18:05:46 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Dec 2016 12:42:53 GMT",
"version": "v2"
}
] |
2017-04-26
|
[
[
"Almeida",
"C. R.",
""
],
[
"Batista",
"A. B.",
""
],
[
"Fabris",
"J. C.",
""
],
[
"Moniz",
"P. V.",
""
]
] |
In this paper, the problem of the self-adjointness for the case of a quantum minisuperspace Hamiltonian retrieved from a Brans-Dicke (BD) action is investigated. Our matter content is presented in terms of a perfect fluid, onto which the Schutz's formalism will be applied. We use the von Neumann theorem and the similarity with the Laplacian operator in one of the variables to determine the cases where the Hamiltonian is self-adjoint and if it admits self-adjoint extensions. For the latter, we study which extension is physically more suitable.
|
gr-qc/0006086
|
Diego F. Torres
|
S. Capozziello, G. Lambiase and Diego F. Torres
|
Cerenkov radiation and scalar stars
|
Accepted for publication in Class. Quantum Grav
|
Class.Quant.Grav. 17 (2000) 3171-3182
|
10.1088/0264-9381/17/16/306
| null |
gr-qc
| null |
We explore the possibility that a charged particle moving in the
gravitational field generated by a scalar star could radiate energy via a
recently proposed gravitational \v{C}erenkov mechanism. We numerically prove
that this is not possible for stable boson stars. We also show that soliton
stars could have \v{C}erenkov radiation for particular values of the boson
mass, although diluteness of the star grows and actual observational
possibility decreases for the more usually discussed boson masses. These
conclusions diminish, although do not completely rule out, the observational
possibility of actually detecting scalar stars using this mechanism, and lead
us to consider other forms, like gravitational lensing.
|
[
{
"created": "Fri, 23 Jun 2000 16:55:00 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Capozziello",
"S.",
""
],
[
"Lambiase",
"G.",
""
],
[
"Torres",
"Diego F.",
""
]
] |
We explore the possibility that a charged particle moving in the gravitational field generated by a scalar star could radiate energy via a recently proposed gravitational \v{C}erenkov mechanism. We numerically prove that this is not possible for stable boson stars. We also show that soliton stars could have \v{C}erenkov radiation for particular values of the boson mass, although diluteness of the star grows and actual observational possibility decreases for the more usually discussed boson masses. These conclusions diminish, although do not completely rule out, the observational possibility of actually detecting scalar stars using this mechanism, and lead us to consider other forms, like gravitational lensing.
|
1209.0718
|
Chad Hanna
|
Kipp Cannon, Chad Hanna, Drew Keppel
|
A method to estimate the significance of coincident gravitational-wave
observations from compact binary coalescence
| null | null |
10.1103/PhysRevD.88.024025
| null |
gr-qc astro-ph.IM
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Coalescing compact binary systems consisting of neutron stars and/or black
holes should be detectable with upcoming advanced gravitational-wave detectors
such as LIGO, Virgo, GEO and {KAGRA}. Gravitational-wave experiments to date
have been riddled with non-Gaussian, non-stationary noise that makes it
challenging to ascertain the significance of an event. A popular method to
estimate significance is to time shift the events collected between detectors
in order to establish a false coincidence rate. Here we propose a method for
estimating the false alarm probability of events using variables commonly
available to search candidates that does not rely on explicitly time shifting
the events while still capturing the non-Gaussianity of the data. We present a
method for establishing a statistical detection of events in the case where
several silver-plated (3--5$\sigma$) events exist but not necessarily any
gold-plated ($>5\sigma$) events. We use LIGO data and a simulated, realistic,
blind signal population to test our method.
|
[
{
"created": "Tue, 4 Sep 2012 17:58:54 GMT",
"version": "v1"
}
] |
2013-08-09
|
[
[
"Cannon",
"Kipp",
""
],
[
"Hanna",
"Chad",
""
],
[
"Keppel",
"Drew",
""
]
] |
Coalescing compact binary systems consisting of neutron stars and/or black holes should be detectable with upcoming advanced gravitational-wave detectors such as LIGO, Virgo, GEO and {KAGRA}. Gravitational-wave experiments to date have been riddled with non-Gaussian, non-stationary noise that makes it challenging to ascertain the significance of an event. A popular method to estimate significance is to time shift the events collected between detectors in order to establish a false coincidence rate. Here we propose a method for estimating the false alarm probability of events using variables commonly available to search candidates that does not rely on explicitly time shifting the events while still capturing the non-Gaussianity of the data. We present a method for establishing a statistical detection of events in the case where several silver-plated (3--5$\sigma$) events exist but not necessarily any gold-plated ($>5\sigma$) events. We use LIGO data and a simulated, realistic, blind signal population to test our method.
|
gr-qc/0102053
|
Howard E. Abrams
|
Leonard S. Abrams
|
The Total Space-Time of a Point-Mass When the Cosmological Constant is
Nonzero and Its Consequences for the Lake-Roeder Black Hole
|
9 pages
|
Physica A227 (1996) 131-140
|
10.1016/0378-4371(95)00383-5
| null |
gr-qc
| null |
Singularities associated with an incomplete space-time (S) are not
well-defined until a boundary is attached to it. Moreover, each boundary gives
rise to a different singularity structure for the resulting total space-time
(TST). Since S is compatible with a variety of boundaries, it therefore does
not represent a unique universe, but instead corresponds to a family of
universes, one for each possible boundary.
It is shown that in the case of Weyl's space-time for a point-mass with
nonzero cosmological constant, the boundary which he attached is invalid, and
when the correct one is attached, the resulting TST is inextendible. This
implies that the Lake-Roeder black hole cannot be produced by gravitational
collapse.
|
[
{
"created": "Mon, 12 Feb 2001 23:35:11 GMT",
"version": "v1"
}
] |
2015-06-25
|
[
[
"Abrams",
"Leonard S.",
""
]
] |
Singularities associated with an incomplete space-time (S) are not well-defined until a boundary is attached to it. Moreover, each boundary gives rise to a different singularity structure for the resulting total space-time (TST). Since S is compatible with a variety of boundaries, it therefore does not represent a unique universe, but instead corresponds to a family of universes, one for each possible boundary. It is shown that in the case of Weyl's space-time for a point-mass with nonzero cosmological constant, the boundary which he attached is invalid, and when the correct one is attached, the resulting TST is inextendible. This implies that the Lake-Roeder black hole cannot be produced by gravitational collapse.
|
2310.02741
|
Genly Le\'on
|
Alfredo D. Millano (Catolica del Norte U.), Genly Leon (Catolica del
Norte U. and DUT, Durban)
|
Averaging generalized scalar field cosmologies IV: locally rotationally
symmetric Bianchi V model
|
Research Program Averaging Generalized Scalar Field Cosmologies, part
IV. 40 pages, 4 compound figures. Updated references
| null | null | null |
gr-qc astro-ph.CO math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This research focuses on scalar field cosmologies with a generalized harmonic
potential. Our attention is centred on the anisotropic LRS Bianchi I and III
metrics, Bianchi V metrics, and their isotropic limits. We provide a
comprehensive overview of the first two metrics classes and offer new findings
for Bianchi V metrics. We show that the Hubble parameter is a time-dependent
perturbation parameter that controls the magnitude of the error between
full-system and time-averaged solutions as it decreases, such that those
complete and time-averaged systems have the same asymptotic behaviour.
Therefore, oscillations entering the system can be controlled and smoothed out,
which simplifies the problem at hand.
|
[
{
"created": "Wed, 4 Oct 2023 11:32:19 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Oct 2023 22:34:13 GMT",
"version": "v2"
}
] |
2023-10-16
|
[
[
"Millano",
"Alfredo D.",
"",
"Catolica del Norte U."
],
[
"Leon",
"Genly",
"",
"Catolica del\n Norte U. and DUT, Durban"
]
] |
This research focuses on scalar field cosmologies with a generalized harmonic potential. Our attention is centred on the anisotropic LRS Bianchi I and III metrics, Bianchi V metrics, and their isotropic limits. We provide a comprehensive overview of the first two metrics classes and offer new findings for Bianchi V metrics. We show that the Hubble parameter is a time-dependent perturbation parameter that controls the magnitude of the error between full-system and time-averaged solutions as it decreases, such that those complete and time-averaged systems have the same asymptotic behaviour. Therefore, oscillations entering the system can be controlled and smoothed out, which simplifies the problem at hand.
|
2111.09569
|
Bijan Bagchi
|
Bijan Bagchi, Sauvik Sen
|
Tunneling of Hawking radiation for BTZ black hole revisited
|
8 pages; accepted in Int. J. Mod. Phys. A. arXiv admin note:
substantial text overlap with arXiv:2105.12423
|
Int. J. Mod. Phys. A 37, 2150252 (2022)
|
10.1142/S0217751X21502523
| null |
gr-qc hep-th quant-ph
|
http://creativecommons.org/publicdomain/zero/1.0/
|
We re-examine Hawking radiation for a nonrotating (2+1)-dimensional BTZ black
hole and evaluate the transmission probability of tunneling through the barrier
of the event horizon employing the standard method of WKB approximation. Our
results are presented for both uncharged and charged cases. We also explore the
associated thermodynamics in terms of Hawking temperature and provide estimates
of black hole parameters like the surface gravity and entropy.
|
[
{
"created": "Thu, 18 Nov 2021 08:09:31 GMT",
"version": "v1"
}
] |
2022-08-18
|
[
[
"Bagchi",
"Bijan",
""
],
[
"Sen",
"Sauvik",
""
]
] |
We re-examine Hawking radiation for a nonrotating (2+1)-dimensional BTZ black hole and evaluate the transmission probability of tunneling through the barrier of the event horizon employing the standard method of WKB approximation. Our results are presented for both uncharged and charged cases. We also explore the associated thermodynamics in terms of Hawking temperature and provide estimates of black hole parameters like the surface gravity and entropy.
|
0802.0043
|
Jiliang Jing
|
Jiliang Jing, Qiyuan Pan
|
Quasinormal modes and second order thermodynamic phase transition for
Reissner-Nordstr\"om black hole
|
10 pages, 5 figures
|
Phys.Lett.B660:13-18,2008
|
10.1016/j.physletb.2007.11.039
| null |
gr-qc astro-ph hep-th
| null |
The relation between the quasinormal modes (QNMs) and the second order
thermodynamic phase transition (SOTPT) for the Reissner-Nordstr\"om (RN) black
hole is studied. It is shown that the quasinormal frequencies of the RN black
hole start to get a spiral-like shape in the complex $\omega$ plane and both
the real and imaginary parts become the oscillatory functions of the charge if
the real part of the quasinormal frequencies arrives at its maximum at the
second order phase transition point of Davies for given overtone number and
angular quantum number. That is to say, we can find out the SOTPT point from
the QNMs of the RN black hole. The fact shows that the quasinormal frequencies
carry the thermodynamical information of the RN black hole.
|
[
{
"created": "Fri, 1 Feb 2008 01:36:52 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Jing",
"Jiliang",
""
],
[
"Pan",
"Qiyuan",
""
]
] |
The relation between the quasinormal modes (QNMs) and the second order thermodynamic phase transition (SOTPT) for the Reissner-Nordstr\"om (RN) black hole is studied. It is shown that the quasinormal frequencies of the RN black hole start to get a spiral-like shape in the complex $\omega$ plane and both the real and imaginary parts become the oscillatory functions of the charge if the real part of the quasinormal frequencies arrives at its maximum at the second order phase transition point of Davies for given overtone number and angular quantum number. That is to say, we can find out the SOTPT point from the QNMs of the RN black hole. The fact shows that the quasinormal frequencies carry the thermodynamical information of the RN black hole.
|
1801.03745
|
Alexander Isayev
|
A. A. Isayev
|
General relativistic polytropes in anisotropic stars
|
27 pages, including 4 figures and 2 tables
|
Phys. Rev. D 96: 083007, 2017
|
10.1103/PhysRevD.96.083007
| null |
gr-qc astro-ph.HE hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Spherically symmetric relativistic stars with the polytropic equation of
state (EoS), which possess the local pressure anisotropy, are considered within
the framework of general relativity. The generalized Lane-Emden equations are
derived for the arbitrary anisotropy parameter $\Delta=p_t-p_r$ ($p_t$ and
$p_r$ being the transverse and radial pressure, respectively). They are then
applied to some special ansatz for the anisotropy parameter in the form of the
differential relation between the anisotropy parameter $\Delta$ and the metric
function $\nu$. The analytical solutions of the obtained equations are found
for incompressible fluid stars and then used for getting their mass-radius
relation, gravitational and binding energy. Also, following the Chandrasekhar
variational approach, the dynamical stability of incompressible anisotropic
fluid stars with the polytropic EoS against radial oscillations is studied. It
is shown that the local pressure anisotropy with $p_t>p_r$ can make the
incompressible fluid stars unstable with respect to radial oscillations, in
contrast to incompressible isotropic fluid stars with the polytropic EoS which
are dynamically stable.
|
[
{
"created": "Thu, 11 Jan 2018 13:19:19 GMT",
"version": "v1"
}
] |
2018-01-12
|
[
[
"Isayev",
"A. A.",
""
]
] |
Spherically symmetric relativistic stars with the polytropic equation of state (EoS), which possess the local pressure anisotropy, are considered within the framework of general relativity. The generalized Lane-Emden equations are derived for the arbitrary anisotropy parameter $\Delta=p_t-p_r$ ($p_t$ and $p_r$ being the transverse and radial pressure, respectively). They are then applied to some special ansatz for the anisotropy parameter in the form of the differential relation between the anisotropy parameter $\Delta$ and the metric function $\nu$. The analytical solutions of the obtained equations are found for incompressible fluid stars and then used for getting their mass-radius relation, gravitational and binding energy. Also, following the Chandrasekhar variational approach, the dynamical stability of incompressible anisotropic fluid stars with the polytropic EoS against radial oscillations is studied. It is shown that the local pressure anisotropy with $p_t>p_r$ can make the incompressible fluid stars unstable with respect to radial oscillations, in contrast to incompressible isotropic fluid stars with the polytropic EoS which are dynamically stable.
|
2312.17214
|
Sang-Eon Bak
|
Sang-Eon Bak, Maulik Parikh, Sudipta Sarkar, and Francesco Setti
|
Quantum-Gravitational Null Raychaudhuri Equation
|
15 pages, 1 figure, v2. published version in JHEP
|
JHEP 07 (2024) 214
|
10.1007/JHEP07(2024)214
| null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
We consider a congruence of null geodesics in the presence of a quantized
spacetime metric. The coupling to a quantum metric induces fluctuations in the
congruence; we calculate the change in the area of a pencil of geodesics
induced by such fluctuations. For the gravitational field in its vacuum state,
we find that quantum gravity contributes a correction to the null Raychaudhuri
equation which is of the same sign as the classical terms. We thus derive a
quantum-gravitational focusing theorem valid for linearized quantum gravity.
|
[
{
"created": "Thu, 28 Dec 2023 18:45:47 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jul 2024 20:34:36 GMT",
"version": "v2"
}
] |
2024-07-29
|
[
[
"Bak",
"Sang-Eon",
""
],
[
"Parikh",
"Maulik",
""
],
[
"Sarkar",
"Sudipta",
""
],
[
"Setti",
"Francesco",
""
]
] |
We consider a congruence of null geodesics in the presence of a quantized spacetime metric. The coupling to a quantum metric induces fluctuations in the congruence; we calculate the change in the area of a pencil of geodesics induced by such fluctuations. For the gravitational field in its vacuum state, we find that quantum gravity contributes a correction to the null Raychaudhuri equation which is of the same sign as the classical terms. We thus derive a quantum-gravitational focusing theorem valid for linearized quantum gravity.
|
0904.4572
|
Marco Pizzi
|
M. Pizzi
|
The time factor in the semi-classical approach to the Hawking radiation
|
10 pages, submitted 30/12/2008; v2 minor changes
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Hawking radiation in the semi-classical approach is re-considered. In the
so-called "Angheben method" for the calculation of the imaginary part of the
action it was missed the temporal part contribution. This has been recently
noticed by Akhmedov et \textsl{al.}, but also there the time part was not
properly considered, the sign being reversed. We show that using the
semi-classical approach on a fixed background it is not possible to find any
tunneling effect from the interior to the exterior of the Schwarzschild black
hole. The same critic applies to the derivations which use the Painleve
coordinates: also in this procedure it was missed the temporal factor
contribution. In this way it is naturally solved also the "factor-two-problem".
|
[
{
"created": "Wed, 29 Apr 2009 10:28:42 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jun 2009 09:58:05 GMT",
"version": "v2"
}
] |
2009-06-25
|
[
[
"Pizzi",
"M.",
""
]
] |
The Hawking radiation in the semi-classical approach is re-considered. In the so-called "Angheben method" for the calculation of the imaginary part of the action it was missed the temporal part contribution. This has been recently noticed by Akhmedov et \textsl{al.}, but also there the time part was not properly considered, the sign being reversed. We show that using the semi-classical approach on a fixed background it is not possible to find any tunneling effect from the interior to the exterior of the Schwarzschild black hole. The same critic applies to the derivations which use the Painleve coordinates: also in this procedure it was missed the temporal factor contribution. In this way it is naturally solved also the "factor-two-problem".
|
2207.08508
|
Miloslav Znojil
|
Miloslav Znojil
|
Wheeler-DeWitt equation and the applicability of crypto-Hermitian
interaction representation in quantum cosmology
|
33 pp., 3 pictures
|
Universe 8 (2022) 385
|
10.3390/universe8070385
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
Recently, Wang with Stankiewicz (Phys. Lett. B 800 (2020) 135106) opposed the
widespread belief that due to quantization, the Big Bang singularity {\em must}
necessarily get smeared and replaced by a non-singular "Big Bounce" process.
Their claim is supported in a methodically independent manner in which just a
highly schematic model (viz., the discrete and drastically simplified
Wheeler-DeWitt equation) is considered. Our comparatively elementary
argumentation is constructive, based on the assumption that the evolution of
the Universe can fully consistently be described using an innovative, hiddenly
Hermitian version of quantum theory formulated in a properly upgraded Dirac's
interaction picture.
|
[
{
"created": "Mon, 18 Jul 2022 10:58:24 GMT",
"version": "v1"
}
] |
2022-12-21
|
[
[
"Znojil",
"Miloslav",
""
]
] |
Recently, Wang with Stankiewicz (Phys. Lett. B 800 (2020) 135106) opposed the widespread belief that due to quantization, the Big Bang singularity {\em must} necessarily get smeared and replaced by a non-singular "Big Bounce" process. Their claim is supported in a methodically independent manner in which just a highly schematic model (viz., the discrete and drastically simplified Wheeler-DeWitt equation) is considered. Our comparatively elementary argumentation is constructive, based on the assumption that the evolution of the Universe can fully consistently be described using an innovative, hiddenly Hermitian version of quantum theory formulated in a properly upgraded Dirac's interaction picture.
|
gr-qc/0612129
|
Orfeu Bertolami
|
O. Bertolami and C. Carvalho
|
Brane Lorentz Symmetry from Lorentz Breaking in the Bulk
|
11 pages, Latex file with IOP style. To appear in Journal of Physics:
Conference Series. Based on talk present by O.B. at the Third International
Workshop DICE2006, Quantum Mechanics between Decoherence and Determinism: new
aspects from particle physics to cosmology, 11-15 September 2006, Piombino,
Italy. Typos corrected
|
J.Phys.Conf.Ser.67:012009,2007
|
10.1088/1742-6596/67/1/012009
| null |
gr-qc
| null |
We propose the mechanism of spontaneous symmetry breaking of a bulk vector
field as a way to generate the selection of bulk dimensions invisible to the
standard model confined to the brane. By assigning a non-vanishing vacuum value
to the vector field, a direction is singled out in the bulk vacuum, thus
breaking the bulk Lorentz symmetry. We present the condition for induced
Lorentz symmetry on the brane, as phenomenologically required.
|
[
{
"created": "Wed, 20 Dec 2006 15:16:03 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Dec 2006 14:16:54 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Bertolami",
"O.",
""
],
[
"Carvalho",
"C.",
""
]
] |
We propose the mechanism of spontaneous symmetry breaking of a bulk vector field as a way to generate the selection of bulk dimensions invisible to the standard model confined to the brane. By assigning a non-vanishing vacuum value to the vector field, a direction is singled out in the bulk vacuum, thus breaking the bulk Lorentz symmetry. We present the condition for induced Lorentz symmetry on the brane, as phenomenologically required.
|
2012.15001
|
Jianfei Xu
|
Jianfei Xu
|
Gravitational waves in gauge theory gravity with a negative cosmological
constant
|
21 pages, 3 figures
|
Class.Quant.Grav. 39 (2022) 17, 175005
|
10.1088/1361-6382/ac8092
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we discuss the gravitational waves in the context of gauge
theory gravity with a negative cosmological constant. The gauge theory gravity
is a gravity theory under gauge formulation in the language of geometric
algebra. In contrast to general relativity, the background spacetime in gauge
theory gravity is flat, the gauge freedom comes from the fact that equations in
terms of physical quantities should be kept in a covariant form under spacetime
displacement and rotation. Similar to the electromagnetism, the gauge
formulation enables us to interpret the gravitational force as a gauge force on
the background flat spacetime. The dynamical fields that describe the
gravitational interactions are those position and rotation gauge fields
introduced as the requirement of the gauge covariance. The gravitational field
equations can be derived from the least action principle with the action as a
gauge invariant quantity built from the covariant field strength. We discuss
the gravitational wave solutions of the field equations with a negative
cosmological constant, and show that these solutions are of Petrov type-N. We
also discuss the velocity memory effect by calculating the velocity change of
an initially free falling massive particle due to the presence of the
gravitational waves.
|
[
{
"created": "Wed, 30 Dec 2020 01:46:26 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Jan 2021 07:59:20 GMT",
"version": "v2"
},
{
"created": "Sun, 21 Aug 2022 07:07:21 GMT",
"version": "v3"
},
{
"created": "Fri, 9 Sep 2022 07:07:11 GMT",
"version": "v4"
}
] |
2022-09-12
|
[
[
"Xu",
"Jianfei",
""
]
] |
In this paper, we discuss the gravitational waves in the context of gauge theory gravity with a negative cosmological constant. The gauge theory gravity is a gravity theory under gauge formulation in the language of geometric algebra. In contrast to general relativity, the background spacetime in gauge theory gravity is flat, the gauge freedom comes from the fact that equations in terms of physical quantities should be kept in a covariant form under spacetime displacement and rotation. Similar to the electromagnetism, the gauge formulation enables us to interpret the gravitational force as a gauge force on the background flat spacetime. The dynamical fields that describe the gravitational interactions are those position and rotation gauge fields introduced as the requirement of the gauge covariance. The gravitational field equations can be derived from the least action principle with the action as a gauge invariant quantity built from the covariant field strength. We discuss the gravitational wave solutions of the field equations with a negative cosmological constant, and show that these solutions are of Petrov type-N. We also discuss the velocity memory effect by calculating the velocity change of an initially free falling massive particle due to the presence of the gravitational waves.
|
gr-qc/9708053
|
Madore
|
J. Madore, L.A. Saeger
|
Topology at the Planck Length
|
Orsay Preprint 97/34, 17 pages, Latex
|
Class.Quant.Grav. 15 (1998) 811-826
|
10.1088/0264-9381/15/4/009
| null |
gr-qc hep-th
| null |
A basic arbitrariness in the determination of the topology of a manifold at
the Planck length is discussed. An explicit example is given of a `smooth'
change in topology from the 2-sphere to the 2-torus through a sequence of
noncommuting geometries. Applications are considered to the theory of D-branes
within the context of the proposed $M$(atrix) theory.
|
[
{
"created": "Fri, 22 Aug 1997 15:30:57 GMT",
"version": "v1"
}
] |
2009-10-30
|
[
[
"Madore",
"J.",
""
],
[
"Saeger",
"L. A.",
""
]
] |
A basic arbitrariness in the determination of the topology of a manifold at the Planck length is discussed. An explicit example is given of a `smooth' change in topology from the 2-sphere to the 2-torus through a sequence of noncommuting geometries. Applications are considered to the theory of D-branes within the context of the proposed $M$(atrix) theory.
|
1404.7123
|
Mubasher Jamil
|
Mubasher Jamil, Saqib Hussain, Bushra Majeed
|
Dynamics of Particles Around a Schwarzschild-like Black Hole in the
Presence of Quintessence and Magnetic Field
|
25 pages, 17 figures, accepted for publication in the European
Physical Journal C
|
Eur. Phys. J. C (2015) 75:24
|
10.1140/epjc/s10052-014-3230-7
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the dynamics of a neutral and a charged particle around a
static and spherically symmetric black hole in the presence of quintessence
matter and external magnetic field. We explore the conditions under which the
particle moving around the black hole could escape to infinity after colliding
with another particle. The innermost stable circular orbit (ISCO) for the
particles are studied in detail. Mainly the dependence of ISCO on dark energy
and on the presence of external magnetic field in the vicinity of black hole is
discussed. By using the Lyapunov exponent, we compare the stabilities of the
orbits of the particles in the presence and absence of dark energy and magnetic
field. The expressions for the center of mass energies of the colliding
particles near the horizon of the black hole are derived. The effective force
on the particles due to dark energy and magnetic field in the vicinity of black
hole is also discussed.
|
[
{
"created": "Mon, 28 Apr 2014 13:36:26 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Nov 2014 04:26:43 GMT",
"version": "v2"
},
{
"created": "Wed, 21 Jan 2015 09:49:57 GMT",
"version": "v3"
}
] |
2015-01-26
|
[
[
"Jamil",
"Mubasher",
""
],
[
"Hussain",
"Saqib",
""
],
[
"Majeed",
"Bushra",
""
]
] |
We investigate the dynamics of a neutral and a charged particle around a static and spherically symmetric black hole in the presence of quintessence matter and external magnetic field. We explore the conditions under which the particle moving around the black hole could escape to infinity after colliding with another particle. The innermost stable circular orbit (ISCO) for the particles are studied in detail. Mainly the dependence of ISCO on dark energy and on the presence of external magnetic field in the vicinity of black hole is discussed. By using the Lyapunov exponent, we compare the stabilities of the orbits of the particles in the presence and absence of dark energy and magnetic field. The expressions for the center of mass energies of the colliding particles near the horizon of the black hole are derived. The effective force on the particles due to dark energy and magnetic field in the vicinity of black hole is also discussed.
|
0709.3958
|
Sophonie Blaise Tchapnda
|
S. B. Tchapnda
|
The plane symmetric Einstein-dust system with positive cosmological
constant
|
12 pages
| null | null | null |
gr-qc
| null |
The Einstein equations with a positive cosmological constant are coupled to
the pressureless perfect fluid matter in plane symmetry. Under suitable
restrictions on the initial data, the resulting Einstein-dust system is proved
to have a global classical solution in the future time direction. Some late
time asymptotic properties are obtained as well.
|
[
{
"created": "Tue, 25 Sep 2007 14:12:39 GMT",
"version": "v1"
}
] |
2007-09-26
|
[
[
"Tchapnda",
"S. B.",
""
]
] |
The Einstein equations with a positive cosmological constant are coupled to the pressureless perfect fluid matter in plane symmetry. Under suitable restrictions on the initial data, the resulting Einstein-dust system is proved to have a global classical solution in the future time direction. Some late time asymptotic properties are obtained as well.
|
1303.3379
|
Mikhail Gorbatenko
|
M.V. Gorbatenko, V.P. Neznamov
|
Quantum-mechanical nonequivalence of metrics of centrally symmetric
uncharged gravitational field
|
21 pages
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Quantum-mechanical analysis shows that the metrics of a centrally symmetric
uncharged gravitational field, which are exact solutions of the general
relativity equations, are physically non-equivalent. The classical
Schwarzschield metric and the Schwarzschild metrics in isotropic and harmonic
coordinates provide for the existence of stationary bound states of Dirac
particles with a real energy spectrum. The Hilbert condition g_{00}>0 is
responsible for zero values of the wave functions under the "event horizon"
that leads to the absence of Hawking radiation. For the Eddington-Finkelstein
and Painleve-Gullstrand metrics, stationary bound states of spin-half particles
cannot exist because Dirac Hamiltonians are non-Hermitian. For these metrics,
the condition g_{00}>0 also leads to the absence of Hawking evaporation. For
the Finkelstein-Lemaitre and Kruskal metrics, Dirac Hamiltonians are explicitly
time-dependent, and stationary bound states of spin-half particles cannot exist
for them. The Hilbert condition for these metrics does not place any
constraints on the domains of the wave functions. Hawking evaporation of black
holes is possible in this case. The results can lead to revisiting some
concepts of the standard cosmological model related to the evolution of the
universe and interaction of collapsars with surrounding matter.
|
[
{
"created": "Thu, 14 Mar 2013 08:44:18 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Jul 2013 16:41:03 GMT",
"version": "v2"
},
{
"created": "Fri, 2 Aug 2013 06:05:15 GMT",
"version": "v3"
}
] |
2013-08-05
|
[
[
"Gorbatenko",
"M. V.",
""
],
[
"Neznamov",
"V. P.",
""
]
] |
Quantum-mechanical analysis shows that the metrics of a centrally symmetric uncharged gravitational field, which are exact solutions of the general relativity equations, are physically non-equivalent. The classical Schwarzschield metric and the Schwarzschild metrics in isotropic and harmonic coordinates provide for the existence of stationary bound states of Dirac particles with a real energy spectrum. The Hilbert condition g_{00}>0 is responsible for zero values of the wave functions under the "event horizon" that leads to the absence of Hawking radiation. For the Eddington-Finkelstein and Painleve-Gullstrand metrics, stationary bound states of spin-half particles cannot exist because Dirac Hamiltonians are non-Hermitian. For these metrics, the condition g_{00}>0 also leads to the absence of Hawking evaporation. For the Finkelstein-Lemaitre and Kruskal metrics, Dirac Hamiltonians are explicitly time-dependent, and stationary bound states of spin-half particles cannot exist for them. The Hilbert condition for these metrics does not place any constraints on the domains of the wave functions. Hawking evaporation of black holes is possible in this case. The results can lead to revisiting some concepts of the standard cosmological model related to the evolution of the universe and interaction of collapsars with surrounding matter.
|
2303.16326
|
Erickson Tjoa
|
Erickson Tjoa
|
Fuzzy spacetime: fundamental limits of quantum-optical holographic bulk
reconstruction
|
10 pages, no figure. Essay written for the Gravity Research
Foundation 2023 Awards for Essays on Gravitation; v2: fixed attribution and
typos
| null | null | null |
gr-qc quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this Essay we construct a concrete, non-perturbative realization of metric
reconstruction using quantum-optical model of particle detectors in
relativistic quantum information. The non-perturbative approach allows us to
realize a version of "short-distance physics corresponds to poor statistics"
idea by Kempf which occurs way above the Planck scale before one reaches the
quantum-gravitational regime. In particular, the "fuzziness" of spacetime that
arise from operational measurement protocols can be given a holographic dual
interpretation using bulk-to-boundary correspondence between scalar correlators
in asymptotically flat spacetimes. The holographic interpretation necessitates
imperfect metric reconstruction even in principle due to the universality of
future null infinity.
|
[
{
"created": "Tue, 28 Mar 2023 21:59:05 GMT",
"version": "v1"
},
{
"created": "Tue, 30 May 2023 18:17:42 GMT",
"version": "v2"
}
] |
2023-06-01
|
[
[
"Tjoa",
"Erickson",
""
]
] |
In this Essay we construct a concrete, non-perturbative realization of metric reconstruction using quantum-optical model of particle detectors in relativistic quantum information. The non-perturbative approach allows us to realize a version of "short-distance physics corresponds to poor statistics" idea by Kempf which occurs way above the Planck scale before one reaches the quantum-gravitational regime. In particular, the "fuzziness" of spacetime that arise from operational measurement protocols can be given a holographic dual interpretation using bulk-to-boundary correspondence between scalar correlators in asymptotically flat spacetimes. The holographic interpretation necessitates imperfect metric reconstruction even in principle due to the universality of future null infinity.
|
gr-qc/0209073
|
Michael T. Anderson
|
Michael T. Anderson
|
Regularity for Lorentz Metrics under Curvature Bounds
|
18pp
|
J.Math.Phys. 44 (2003) 2994-3012
|
10.1063/1.1580199
| null |
gr-qc math.DG
| null |
Let (M, g) be an (n+1) dimensional space-time, with bounded curvature with
respect to a bounded framing. If (M, g) is vacuum or satisfies a mild condition
on the stress-energy tensor, then we show that (M, g) locally admits coordinate
systems in which the Lorentz metric is well-controlled in the (space-time)
Sobolev space L^{2,p}, for any finite p.
|
[
{
"created": "Fri, 20 Sep 2002 16:20:41 GMT",
"version": "v1"
}
] |
2015-06-25
|
[
[
"Anderson",
"Michael T.",
""
]
] |
Let (M, g) be an (n+1) dimensional space-time, with bounded curvature with respect to a bounded framing. If (M, g) is vacuum or satisfies a mild condition on the stress-energy tensor, then we show that (M, g) locally admits coordinate systems in which the Lorentz metric is well-controlled in the (space-time) Sobolev space L^{2,p}, for any finite p.
|
2408.01205
|
Lai Zhao
|
Lai Zhao, Meirong Tang, Zhaoyi Xu
|
Gravitational Lensing Effects and Observational Behaviors of the
Rotating Short-Hairy Black Hole
| null | null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The successful capture of black hole(BH) images by the Event Horizon
Telescope(EHT) has sparked a surge in research on strong gravitational lensing,
providing new methods for studying behavior near the event horizon of BHs. For
the short-hair that has significant effects only near the BH event horizon,
studying its strong gravitational lensing effects helps to understand the
nature of this hair. This paper explores the behaviors of the rotating
short-hairy BH in strong gravitational lensing. Simulations show that the
short-hair parameter results in a smaller event horizon radius, photon sphere,
and impact parameter compared to the Kerr BH. Moreover, the lensing
coefficients $ \bar{a} $ and $ \bar{b} $ show opposite trends due to the
short-hair parameter $ Q_m $, with the former increasing and the latter
decreasing. It is worth mentioning that in certain cases, the short-hair
parameter can make $ \bar{b} $ slightly higher than that of the Kerr BH. The
deflection angle $ \alpha_D $ decreases with an increasing impact parameter and
diverges at $ u_m $, with the divergent impact parameter of rotating
short-hairy BH being smaller than that of the Kerr BH. In the context of
$M87^*$ and $Sgr A^*$ BHs, their Einstein rings, relativistic images, and time
delays differ significantly from those of the Kerr BH. Although current
equipment cannot yet distinguish these differences, future high-precision
instruments are expected to achieve this goal, thereby differentiating rotating
short-hairy BH from the Kerr BH, exploring the nature of the short-hair, and
testing the no-hair theorem of BH. This provides a new perspective for
understanding the extreme physical environments of BHs and offers necessary
references for future observational and theoretical research.
|
[
{
"created": "Fri, 2 Aug 2024 11:38:08 GMT",
"version": "v1"
}
] |
2024-08-05
|
[
[
"Zhao",
"Lai",
""
],
[
"Tang",
"Meirong",
""
],
[
"Xu",
"Zhaoyi",
""
]
] |
The successful capture of black hole(BH) images by the Event Horizon Telescope(EHT) has sparked a surge in research on strong gravitational lensing, providing new methods for studying behavior near the event horizon of BHs. For the short-hair that has significant effects only near the BH event horizon, studying its strong gravitational lensing effects helps to understand the nature of this hair. This paper explores the behaviors of the rotating short-hairy BH in strong gravitational lensing. Simulations show that the short-hair parameter results in a smaller event horizon radius, photon sphere, and impact parameter compared to the Kerr BH. Moreover, the lensing coefficients $ \bar{a} $ and $ \bar{b} $ show opposite trends due to the short-hair parameter $ Q_m $, with the former increasing and the latter decreasing. It is worth mentioning that in certain cases, the short-hair parameter can make $ \bar{b} $ slightly higher than that of the Kerr BH. The deflection angle $ \alpha_D $ decreases with an increasing impact parameter and diverges at $ u_m $, with the divergent impact parameter of rotating short-hairy BH being smaller than that of the Kerr BH. In the context of $M87^*$ and $Sgr A^*$ BHs, their Einstein rings, relativistic images, and time delays differ significantly from those of the Kerr BH. Although current equipment cannot yet distinguish these differences, future high-precision instruments are expected to achieve this goal, thereby differentiating rotating short-hairy BH from the Kerr BH, exploring the nature of the short-hair, and testing the no-hair theorem of BH. This provides a new perspective for understanding the extreme physical environments of BHs and offers necessary references for future observational and theoretical research.
|
gr-qc/0703051
|
L\'aszl\'o \'A Gergely
|
L\'aszl\'o \'A. Gergely
|
Black holes on cosmological branes
|
to appear in the Proceedings of the Eleventh Marcel Grossmann Meeting
2006, World Scientific, Singapore (2007)
| null |
10.1142/9789812834300_0524
| null |
gr-qc
| null |
While in general relativity black holes can be freely embedded into a
cosmological background, the same problem in brane-worlds is much more
cumbersome. We present here the results obtained so far in the explicit
constructions of such space-times. We also discuss gravitational collapse in
this context.
|
[
{
"created": "Thu, 8 Mar 2007 11:15:11 GMT",
"version": "v1"
}
] |
2016-11-15
|
[
[
"Gergely",
"László Á.",
""
]
] |
While in general relativity black holes can be freely embedded into a cosmological background, the same problem in brane-worlds is much more cumbersome. We present here the results obtained so far in the explicit constructions of such space-times. We also discuss gravitational collapse in this context.
|
2405.03719
|
Christian Wiesendanger
|
C Wiesendanger
|
Schwarzschild Solution within a new renormalizable SO(1,3) Gauge Field
Theory of Gravitation
|
16 Pages
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The existence of the Schwarzschild solution is demonstrated within a new
SO(1,3) gauge field theory whose fundamental gauge field B is of dimension one
allowing for the renormalizability of the full quantum theory. On the other
hand the classically dominant term of the gauge field action can be expressed
in terms of a naturally emerging Vierbein of dimension zero. In fact this
action term is the same functional of the emerging Vierbein e[B] as is the
Einstein-Hilbert action of the Vierbein in General Relativity (GR), albeit with
e[B] subject to a constraint. To solve the Einstein equations a spherically
symmetric Ansatz for e[B] respecting the constraint is determined and
transformed into the standard metric used to calculate the Schwarzschild
solution. This allows to prove the latter's existence making the present theory
a perfectly viable theory of gravitation equivalent to GR at the classical
level.
|
[
{
"created": "Sun, 5 May 2024 16:43:29 GMT",
"version": "v1"
}
] |
2024-05-08
|
[
[
"Wiesendanger",
"C",
""
]
] |
The existence of the Schwarzschild solution is demonstrated within a new SO(1,3) gauge field theory whose fundamental gauge field B is of dimension one allowing for the renormalizability of the full quantum theory. On the other hand the classically dominant term of the gauge field action can be expressed in terms of a naturally emerging Vierbein of dimension zero. In fact this action term is the same functional of the emerging Vierbein e[B] as is the Einstein-Hilbert action of the Vierbein in General Relativity (GR), albeit with e[B] subject to a constraint. To solve the Einstein equations a spherically symmetric Ansatz for e[B] respecting the constraint is determined and transformed into the standard metric used to calculate the Schwarzschild solution. This allows to prove the latter's existence making the present theory a perfectly viable theory of gravitation equivalent to GR at the classical level.
|
gr-qc/0009033
|
D. V. Ahluwalia
|
D. V. Ahluwalia
|
Principle of equivalence and wave-particle duality in quantum gravity
|
Invited talk at the III Workshop of DGFM-SMF, Nov. 28-Dec. 03, 1999,
Leon, Mexico
|
Memorias del III Taller de la DGFM-SMF, 2000. ``Aspectos de
Gravitacion y Fisica-Matematica,'' Editors: N. Breton, O. Pimentel, J.
Socorro
| null | null |
gr-qc
| null |
This talk presents: (a) A quantum-mechanically induced violation of the
principle of equivalence, and (b) Gravitationally-induced modification to the
wave particle duality. In this context I note that the agreement between the
predictions of general relativity and observations of the energy loss due to
gravitational waves emitted by binary pulsars is just as impressive as the
agreement between prediction of quantum electrodynamics and the measured value
of Lamb shift in atoms. However, general relativity has not yet yielded to a
successful quantised theory. There is a widespread belief that the two thories
are incompatible at some deep level. The question is: where? Here, I show that
the conceptual foundations of the theory of general relativity and quantum
mechanics are so rich that they suggest concrete modifications into each other
in the interface region. Specifically, I consider quantum states that have no
classical counterpart and show that such states must carry an inherent
violation of the principle of equivalence. On the other hand, I show that when
gravitational effects are incorporated into the quantum measurement process one
must induce a gravitationally induced modification to the de Broglie's
wave-particle duality. The reported changes into the foundations of the two
theories are far from in-principle modifications. These are endowed with
serious implications for the understanding of the early universe and, in
certain instances, can be explored in terrestrial laboratories.
|
[
{
"created": "Mon, 11 Sep 2000 16:38:09 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Ahluwalia",
"D. V.",
""
]
] |
This talk presents: (a) A quantum-mechanically induced violation of the principle of equivalence, and (b) Gravitationally-induced modification to the wave particle duality. In this context I note that the agreement between the predictions of general relativity and observations of the energy loss due to gravitational waves emitted by binary pulsars is just as impressive as the agreement between prediction of quantum electrodynamics and the measured value of Lamb shift in atoms. However, general relativity has not yet yielded to a successful quantised theory. There is a widespread belief that the two thories are incompatible at some deep level. The question is: where? Here, I show that the conceptual foundations of the theory of general relativity and quantum mechanics are so rich that they suggest concrete modifications into each other in the interface region. Specifically, I consider quantum states that have no classical counterpart and show that such states must carry an inherent violation of the principle of equivalence. On the other hand, I show that when gravitational effects are incorporated into the quantum measurement process one must induce a gravitationally induced modification to the de Broglie's wave-particle duality. The reported changes into the foundations of the two theories are far from in-principle modifications. These are endowed with serious implications for the understanding of the early universe and, in certain instances, can be explored in terrestrial laboratories.
|
1506.02505
|
Ahmad Sheykhi
|
A. Sheykhi, M. H. Dehghani and S. Ghaffari
|
New holographic dark energy model inspired by the DGP braneworld
|
11 pages
|
IJMPD, Vol 25, (2016) 1650018
|
10.1142/S0218271816500188
| null |
gr-qc
|
http://creativecommons.org/licenses/by/3.0/
|
The energy density of the holographic dark energy is based on the area law of
entropy, and thus any modification of the area law leads to a modified
holographic energy density. Inspired by the entropy expression associated with
the apparent horizon of a Friedmann-Robertson-Walker (FRW) Universe in DGP
braneworld, we propose a new model for the holographic dark energy in the
framework of DGP brane cosmology. We investigate the cosmological consequences
of this new model and calculate the equation of state parameter by choosing the
Hubble radius, $L = H^{-1}$, as the system's IR cutoff. Our study show that,
due to the effects of the extra dimension (bulk), the identification of
IR-cutoff with Hubble radius, can reproduce the present acceleration of the
Universe expansion. This is in contrast to the ordinary holographic dark energy
in standard cosmology which leads to the zero equation of state parameter in
the case of choosing the Hubble radius as system's IR cutoff in the absence of
interaction between dark matter and dark energy.
|
[
{
"created": "Fri, 5 Jun 2015 05:38:48 GMT",
"version": "v1"
}
] |
2016-03-16
|
[
[
"Sheykhi",
"A.",
""
],
[
"Dehghani",
"M. H.",
""
],
[
"Ghaffari",
"S.",
""
]
] |
The energy density of the holographic dark energy is based on the area law of entropy, and thus any modification of the area law leads to a modified holographic energy density. Inspired by the entropy expression associated with the apparent horizon of a Friedmann-Robertson-Walker (FRW) Universe in DGP braneworld, we propose a new model for the holographic dark energy in the framework of DGP brane cosmology. We investigate the cosmological consequences of this new model and calculate the equation of state parameter by choosing the Hubble radius, $L = H^{-1}$, as the system's IR cutoff. Our study show that, due to the effects of the extra dimension (bulk), the identification of IR-cutoff with Hubble radius, can reproduce the present acceleration of the Universe expansion. This is in contrast to the ordinary holographic dark energy in standard cosmology which leads to the zero equation of state parameter in the case of choosing the Hubble radius as system's IR cutoff in the absence of interaction between dark matter and dark energy.
|
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