id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1111.1071 | Luis Herrera | L. Herrera, A. Di Prisco and J. Iba\~nez | On the Role of Electric Charge and Cosmological Constant in Structure
Scalars | 5 pages Latex. Published in Phys. Rev. D. Some typos corrected | Phys. Rev. D84,107501, (2011) | 10.1103/PhysRevD.84.107501 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The physical meaning of structure scalars is analyzed for charged dissipative
spherical fluids and for neutral dust in the presence of cosmological constant.
The role played by such factors in the structure scalars is clearly brought out
and physical consequences are discussed. Particular attention needs to be paid
to the changes introduced by the above mentioned factors in the inhomogeneity
factor and the evolution of the expansion scalar and the shear tensor.
| [
{
"created": "Fri, 4 Nov 2011 08:58:45 GMT",
"version": "v1"
},
{
"created": "Fri, 18 Nov 2011 16:19:38 GMT",
"version": "v2"
}
] | 2015-06-03 | [
[
"Herrera",
"L.",
""
],
[
"Di Prisco",
"A.",
""
],
[
"Ibañez",
"J.",
""
]
] | The physical meaning of structure scalars is analyzed for charged dissipative spherical fluids and for neutral dust in the presence of cosmological constant. The role played by such factors in the structure scalars is clearly brought out and physical consequences are discussed. Particular attention needs to be paid to the changes introduced by the above mentioned factors in the inhomogeneity factor and the evolution of the expansion scalar and the shear tensor. |
1303.5484 | Maurizio Gasperini | L. Cosmai, G. Fanizza, M. Gasperini and L. Tedesco | Discriminating different models of luminosity-redshift distribution | 11 pages, 6 figures. To appear in Class. Quantum Grav | null | 10.1088/0264-9381/30/9/095011 | BA-TH/672-13 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The beginning of the cosmological phase bearing the direct kinematic imprints
of supernovae dimming may significantly vary within different models of
late-time cosmology, even if such models are able to fit present SNe data at a
comparable level of statistical accuracy. This effect -- useful in principle to
discriminate among different physical interpretations of the
luminosity-redshift relation -- is illustrated here with a pedagogical example
based on the LTB geometry.
| [
{
"created": "Thu, 21 Mar 2013 23:34:54 GMT",
"version": "v1"
}
] | 2015-06-15 | [
[
"Cosmai",
"L.",
""
],
[
"Fanizza",
"G.",
""
],
[
"Gasperini",
"M.",
""
],
[
"Tedesco",
"L.",
""
]
] | The beginning of the cosmological phase bearing the direct kinematic imprints of supernovae dimming may significantly vary within different models of late-time cosmology, even if such models are able to fit present SNe data at a comparable level of statistical accuracy. This effect -- useful in principle to discriminate among different physical interpretations of the luminosity-redshift relation -- is illustrated here with a pedagogical example based on the LTB geometry. |
gr-qc/9304039 | null | J.J.Halliwell | Quantum-Mechanical Histories and the Uncertainty Principle:
I.Information-Theoretic Inequalities | 40 pages (revised uncorrupted version), Imperial College Preprint IC
92-93/26 | Phys.Rev. D48 (1993) 2739-2752 | 10.1103/PhysRevD.48.2739 | null | gr-qc cond-mat hep-th | null | This paper is generally concerned with understanding how the uncertainty
principle arises in formulations of quantum mechanics, such as the decoherent
histories approach, whose central goal is the assignment of probabilities to
histories. We first consider histories characterized by position or momentum
projections at two moments of time. Both exact and approximate (Gaussian)
projections are studied. Shannon information is used as a measure of the
uncertainty expressed in the probabilities for these histories. We derive a
number of inequalities in which the uncertainty principle is expressed as a
lower bound on the information of phase space distributions derived from the
probabilities for two-time histories. We go on to consider histories
characterized by position samplings at $n$ moments of time. We derive a lower
bound on the information of the joint probability for $n$ position samplings.
Similar bounds are derived for histories characterized by samplings of other
variables. All lower bounds on the information of histories have the general
form $\ln \left( V_H / V_S \right) $, where $V_H$ is a volume element of
history space, which we define, and $V_S$ is the volume of that space probed by
the projections. We thus obtain a concise and general form of the uncertainty
principle referring directly to the histories description of the system, and
making no reference to notions of phase space.
| [
{
"created": "Tue, 27 Apr 1993 11:11:00 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Apr 1993 10:42:05 GMT",
"version": "v2"
}
] | 2009-10-22 | [
[
"Halliwell",
"J. J.",
""
]
] | This paper is generally concerned with understanding how the uncertainty principle arises in formulations of quantum mechanics, such as the decoherent histories approach, whose central goal is the assignment of probabilities to histories. We first consider histories characterized by position or momentum projections at two moments of time. Both exact and approximate (Gaussian) projections are studied. Shannon information is used as a measure of the uncertainty expressed in the probabilities for these histories. We derive a number of inequalities in which the uncertainty principle is expressed as a lower bound on the information of phase space distributions derived from the probabilities for two-time histories. We go on to consider histories characterized by position samplings at $n$ moments of time. We derive a lower bound on the information of the joint probability for $n$ position samplings. Similar bounds are derived for histories characterized by samplings of other variables. All lower bounds on the information of histories have the general form $\ln \left( V_H / V_S \right) $, where $V_H$ is a volume element of history space, which we define, and $V_S$ is the volume of that space probed by the projections. We thus obtain a concise and general form of the uncertainty principle referring directly to the histories description of the system, and making no reference to notions of phase space. |
0910.5591 | Evan Goetz | E. Goetz, P. Kalmus, S. Erickson, R. L. Savage Jr., G. Gonzalez, K.
Kawabe, M. Landry, S. Marka, B. O'Reilly, K. Riles, D. Sigg and P. Willems | Precise calibration of LIGO test mass actuators using photon radiation
pressure | 13 pages, 6 figures, accepted by Classical and Quantum Gravity | Class.Quant.Grav.26:245011,2009 | 10.1088/0264-9381/26/24/245011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Precise calibration of kilometer-scale interferometric gravitational wave
detectors is crucial for source localization and waveform reconstruction. A
technique that uses the radiation pressure of a power-modulated auxiliary laser
to induce calibrated displacements of one of the ~10 kg arm cavity mirrors, a
so-called photon calibrator, has been demonstrated previously and has recently
been implemented on the LIGO detectors. In this article, we discuss the
inherent precision and accuracy of the LIGO photon calibrators and several
improvements that have been developed to reduce the estimated voice coil
actuator calibration uncertainties to less than 2 percent (1-sigma). These
improvements include accounting for rotation-induced apparent length variations
caused by interferometer and photon calibrator beam centering offsets, absolute
laser power measurement using temperature-controlled InGaAs photodetectors
mounted on integrating spheres and calibrated by NIST, minimizing errors
induced by localized elastic deformation of the mirror surface by using a
two-beam configuration with the photon calibrator beams symmetrically displaced
about the center of the optic, and simultaneously actuating the test mass with
voice coil actuators and the photon calibrator to minimize fluctuations caused
by the changing interferometer response. The photon calibrator is able to
operate in the most sensitive interferometer configuration, and is expected to
become a primary calibration method for future gravitational wave searches.
| [
{
"created": "Thu, 29 Oct 2009 15:33:33 GMT",
"version": "v1"
}
] | 2010-02-23 | [
[
"Goetz",
"E.",
""
],
[
"Kalmus",
"P.",
""
],
[
"Erickson",
"S.",
""
],
[
"Savage",
"R. L.",
"Jr."
],
[
"Gonzalez",
"G.",
""
],
[
"Kawabe",
"K.",
""
],
[
"Landry",
"M.",
""
],
[
"Marka",
"S.",
""
],
[
"O'Reilly",
"B.",
""
],
[
"Riles",
"K.",
""
],
[
"Sigg",
"D.",
""
],
[
"Willems",
"P.",
""
]
] | Precise calibration of kilometer-scale interferometric gravitational wave detectors is crucial for source localization and waveform reconstruction. A technique that uses the radiation pressure of a power-modulated auxiliary laser to induce calibrated displacements of one of the ~10 kg arm cavity mirrors, a so-called photon calibrator, has been demonstrated previously and has recently been implemented on the LIGO detectors. In this article, we discuss the inherent precision and accuracy of the LIGO photon calibrators and several improvements that have been developed to reduce the estimated voice coil actuator calibration uncertainties to less than 2 percent (1-sigma). These improvements include accounting for rotation-induced apparent length variations caused by interferometer and photon calibrator beam centering offsets, absolute laser power measurement using temperature-controlled InGaAs photodetectors mounted on integrating spheres and calibrated by NIST, minimizing errors induced by localized elastic deformation of the mirror surface by using a two-beam configuration with the photon calibrator beams symmetrically displaced about the center of the optic, and simultaneously actuating the test mass with voice coil actuators and the photon calibrator to minimize fluctuations caused by the changing interferometer response. The photon calibrator is able to operate in the most sensitive interferometer configuration, and is expected to become a primary calibration method for future gravitational wave searches. |
1912.03149 | Kirill Bronnikov | K.A. Bronnikov | Comment on "Linear superposition of regular black hole solutions of
Einstein nonlinear electrodynamics" | 4 pages, no figures | Phys. Rev. D 101, 128501 (2020) | 10.1103/PhysRevD.101.128501 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is argued that in the paper by A.A. Garcia-Diaz and G. Gutierrez-Cano
[Phys. Rev. D 100, 064068 (2019)] on nonlinear electrodynamics coupled to
general relativity, along with some interesting results and useful
observations, many statements are either inaccurate or incomplete. In
particular, the authors only consider solutions with an electric charge,
whereas their magnetic counterparts have features of equal interest, both
similar to and different from those of electric ones. Moreover, it is not
mentioned that in electric solutions with a regular center the Lagrangian
function $L(f)$ ($f = F_{\mu\nu} F^{\mu\nu}$) cannot have a Maxwell weak-field
limit. The observation on superpositions of regular solutions suffers some
inaccuracies. The present Comment tries to fill these and other gaps and to
provide necessary corrections.
| [
{
"created": "Fri, 6 Dec 2019 14:28:05 GMT",
"version": "v1"
}
] | 2020-07-01 | [
[
"Bronnikov",
"K. A.",
""
]
] | It is argued that in the paper by A.A. Garcia-Diaz and G. Gutierrez-Cano [Phys. Rev. D 100, 064068 (2019)] on nonlinear electrodynamics coupled to general relativity, along with some interesting results and useful observations, many statements are either inaccurate or incomplete. In particular, the authors only consider solutions with an electric charge, whereas their magnetic counterparts have features of equal interest, both similar to and different from those of electric ones. Moreover, it is not mentioned that in electric solutions with a regular center the Lagrangian function $L(f)$ ($f = F_{\mu\nu} F^{\mu\nu}$) cannot have a Maxwell weak-field limit. The observation on superpositions of regular solutions suffers some inaccuracies. The present Comment tries to fill these and other gaps and to provide necessary corrections. |
gr-qc/0009097 | Marcelo Alves | M.Alves (F.U.Rio de Janeiro) and V.B.Bezerra (F.U.Paraiba) | Dilaton Gravity with a Non-minmally Coupled Scalar Field | null | Int.J.Mod.Phys. D9 (2000) 697-704 | 10.1142/S0218271800000815 | null | gr-qc hep-th | null | We discuss the two-dimensional dilaton gravity with a scalar field as the
source matter. The coupling between the gravity and the scalar, massless, field
is presented in an unusual form. We work out two examples of these couplings
and solutions with black-hole behaviour are discussed and compared with those
found in the literature.
| [
{
"created": "Thu, 28 Sep 2000 17:58:23 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Alves",
"M.",
"",
"F.U.Rio de Janeiro"
],
[
"Bezerra",
"V. B.",
"",
"F.U.Paraiba"
]
] | We discuss the two-dimensional dilaton gravity with a scalar field as the source matter. The coupling between the gravity and the scalar, massless, field is presented in an unusual form. We work out two examples of these couplings and solutions with black-hole behaviour are discussed and compared with those found in the literature. |
1610.07788 | Diego Pavon | Jos\'e Pedro Mimoso and Diego Pav\'on | Considerations on the thermal equilibrium between matter and the cosmic
horizon | 4 pages, two columns, no figures, matches version published in the
Physical Review | PRD 94, 103507(2016) | 10.1103/PhysRevD.94.103507 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A common feature in the thermodynamic analysis of homogeneous and isotropic
world models is the assumption that the temperature of the fluids inside the
cosmic horizon (including dark energy) coincides with the temperature of the
latter, whether it be either the event or the apparent horizon. We examine up
to what extent this assumption may be justified, given that these temperatures
evolve under different time-temperature laws. We argue that while radiation
cannot reach thermal equilibrium with the horizon, non-relativistic matter may,
and dark energy might though only approximately.
| [
{
"created": "Tue, 25 Oct 2016 08:45:52 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Nov 2016 09:36:16 GMT",
"version": "v2"
}
] | 2016-11-18 | [
[
"Mimoso",
"José Pedro",
""
],
[
"Pavón",
"Diego",
""
]
] | A common feature in the thermodynamic analysis of homogeneous and isotropic world models is the assumption that the temperature of the fluids inside the cosmic horizon (including dark energy) coincides with the temperature of the latter, whether it be either the event or the apparent horizon. We examine up to what extent this assumption may be justified, given that these temperatures evolve under different time-temperature laws. We argue that while radiation cannot reach thermal equilibrium with the horizon, non-relativistic matter may, and dark energy might though only approximately. |
1107.0898 | Jonathan Luk | Jonathan Luk | On the Local Existence for the Characteristic Initial Value Problem in
General Relativity | null | null | null | null | gr-qc math-ph math.AP math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Given a truncated incoming null cone and a truncated outgoing null cone
intersecting at a two sphere $S$ with smooth characteristic initial data, a
theorem of Rendall shows that the vacuum Einstein equations can be solved in a
small neighborhood of $S$ in the future of $S$. We show that in fact the vacuum
Einstein equations can be solved in a neighborhood in the future of the cones,
as long as the constraint equations are initially satisfied on the null cones.
The proof is based on energy type estimates and relies heavily on the null
structure of the Einstein equations in the double null foliation.
| [
{
"created": "Tue, 5 Jul 2011 15:20:00 GMT",
"version": "v1"
}
] | 2011-07-06 | [
[
"Luk",
"Jonathan",
""
]
] | Given a truncated incoming null cone and a truncated outgoing null cone intersecting at a two sphere $S$ with smooth characteristic initial data, a theorem of Rendall shows that the vacuum Einstein equations can be solved in a small neighborhood of $S$ in the future of $S$. We show that in fact the vacuum Einstein equations can be solved in a neighborhood in the future of the cones, as long as the constraint equations are initially satisfied on the null cones. The proof is based on energy type estimates and relies heavily on the null structure of the Einstein equations in the double null foliation. |
gr-qc/0302061 | Kashif Alvi | Kashif Alvi | Note on ingoing coordinates for binary black holes | 5 pages, no figures | Phys.Rev. D67 (2003) 104006 | 10.1103/PhysRevD.67.104006 | null | gr-qc | null | In a previous paper, a binary black hole four-metric was presented in a
post-Newtonian corotating coordinate system valid only up to the holes'
apparent horizons. In this paper, I define an ingoing coordinate transformation
that extends this corotating coordinate system through the holes' horizons and
into their interiors. The motivation for using ingoing coordinates is that
numerical simulations of black holes require the computational grid to extend
inside the horizons. The coordinate transformation presented here makes the
binary black hole four-metric suitable as a source of initial data for
numerical simulations.
| [
{
"created": "Fri, 14 Feb 2003 13:40:15 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Alvi",
"Kashif",
""
]
] | In a previous paper, a binary black hole four-metric was presented in a post-Newtonian corotating coordinate system valid only up to the holes' apparent horizons. In this paper, I define an ingoing coordinate transformation that extends this corotating coordinate system through the holes' horizons and into their interiors. The motivation for using ingoing coordinates is that numerical simulations of black holes require the computational grid to extend inside the horizons. The coordinate transformation presented here makes the binary black hole four-metric suitable as a source of initial data for numerical simulations. |
1806.09961 | Andreas G. A. Pithis | Joseph Ben Geloun and Alexander Kegeles and Andreas G. A. Pithis | Minimizers of the dynamical Boulatov model | closest to published version | Eur. Phys. J. C (2018) 78: 996 | 10.1140/epjc/s10052-018-6483-8 | KCL-PH-TH/2018-7 | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the Euler-Lagrange equation of the dynamical Boulatov model which is
a simplicial model for 3d Euclidean quantum gravity augmented by a
Laplace-Beltrami operator. We provide all its solutions on the space of left
and right invariant functions that render the interaction of the model an
equilateral tetrahedron. Surprisingly, for a non-linear equation of motion, the
solution space forms a vector space. This space distinguishes three classes of
solutions: saddle points, global and local minima of the action. Our analysis
shows that there exists one parameter region of coupling constants for which
the action admits degenerate global minima.
| [
{
"created": "Tue, 26 Jun 2018 13:18:37 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Dec 2018 16:08:44 GMT",
"version": "v2"
}
] | 2018-12-10 | [
[
"Geloun",
"Joseph Ben",
""
],
[
"Kegeles",
"Alexander",
""
],
[
"Pithis",
"Andreas G. A.",
""
]
] | We study the Euler-Lagrange equation of the dynamical Boulatov model which is a simplicial model for 3d Euclidean quantum gravity augmented by a Laplace-Beltrami operator. We provide all its solutions on the space of left and right invariant functions that render the interaction of the model an equilateral tetrahedron. Surprisingly, for a non-linear equation of motion, the solution space forms a vector space. This space distinguishes three classes of solutions: saddle points, global and local minima of the action. Our analysis shows that there exists one parameter region of coupling constants for which the action admits degenerate global minima. |
1904.12670 | Wei Dongdong | Dongdong Wei, Xinhe Meng and Bin Wang | Detecting the processes of colliding plane gravitational waves by
electromagnetic response signals | 9 pages, 25 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we have considered how to detect the processes of plane
gravitational waves colliding. The degenerate Ferrari-Ibanez solution describes
the collision of plane gravitational waves with aligned linear polarization,
and the solution of the interaction region is Schwarzschild-like metric by
taking coordinate transformation, which impels us more interesting to detect
the process to explore. We have calculated explicitly out the solutions of the
electromagnetic field produced by the plane gravitational wave and the
colliding region of plane gravitational waves perturbing a weak magnetic field
background. The magnitudes are so small that the likelihood of detecting
gravitational waves is only just emergence within the range of the most
high-level modern apparatus such as the further upgraded aLIGO, but we can
judge whether the collision process has occurred or not by measuring the
amplitude and waveform of electromagnetic wave properties. Moreover, detecting
electromagnetic waves can offer a new method to verify general relativity.
| [
{
"created": "Mon, 29 Apr 2019 12:56:51 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Jun 2019 11:57:42 GMT",
"version": "v2"
},
{
"created": "Thu, 26 Sep 2019 01:30:07 GMT",
"version": "v3"
}
] | 2019-09-27 | [
[
"Wei",
"Dongdong",
""
],
[
"Meng",
"Xinhe",
""
],
[
"Wang",
"Bin",
""
]
] | In this paper, we have considered how to detect the processes of plane gravitational waves colliding. The degenerate Ferrari-Ibanez solution describes the collision of plane gravitational waves with aligned linear polarization, and the solution of the interaction region is Schwarzschild-like metric by taking coordinate transformation, which impels us more interesting to detect the process to explore. We have calculated explicitly out the solutions of the electromagnetic field produced by the plane gravitational wave and the colliding region of plane gravitational waves perturbing a weak magnetic field background. The magnitudes are so small that the likelihood of detecting gravitational waves is only just emergence within the range of the most high-level modern apparatus such as the further upgraded aLIGO, but we can judge whether the collision process has occurred or not by measuring the amplitude and waveform of electromagnetic wave properties. Moreover, detecting electromagnetic waves can offer a new method to verify general relativity. |
2208.10562 | Anzhong Wang | Geeth Ongole, Hongchao Zhang, Tao Zhu, Anzhong Wang and Bin Wang | Dirac observables in the 4-dimensional phase space of Ashtekar's
variables and spherically symmetric loop quantum black holes | revetex4-1, 2 tables and 13 figures. To appear in Universe for the
Special Issue "Loop Quantum Gravity: A Themed Issue in Honor of Prof. Abhay
Ashtekar" | Universe 8 (2022) 543 | 10.3390/ universe8100543 | null | gr-qc math-ph math.MP quant-ph | http://creativecommons.org/licenses/by/4.0/ | In this paper, we study a proposal put forward recently by Bodendorfer, Mele
and M\"unch and Garc\'\i{}a-Quismondo and Marug\'an, in which the two
polymerization parameters of spherically symmetric black hole spacetimes are
the Dirac observables of the four-dimensional Ashtekar's variables. In this
model, black and white hole horizons in general exist and naturally divide the
spacetime into the external and internal regions. In the external region, the
spacetime can be made asymptotically flat by properly choosing the dependence
of the two polymerization parameters on the Ashtekar variables. Then, we find
that the asymptotical behavior of the spacetime is universal, and, to the
leading order, the curvature invariants are independent of the mass parameter
$m$. For example, the Kretschmann scalar approaches zero as $K \simeq
A_0r^{-4}$ asymptotically, where $A_0$ is generally a non-zero constant and
independent of $m$, and $r$ the geometric radius of the two-spheres. In the
internal region, all the physical quantities are finite, and the Schwarzschild
black hole singularity is replaced by a transition surface whose radius is
always finite and non-zero. The quantum gravitational effects are negligible
near the black hole horizon for very massive black holes. However, the behavior
of the spacetime across the transition surface is significantly different from
all loop quantum black holes studied so far. In particular, the location of the
maximum amplitude of the curvature scalars is displaced from the transition
surface and depends on $m$, so does the maximum amplitude. In addition, the
radius of the white hole is much smaller than that of the black hole, and its
exact value sensitively depends on $m$, too.
| [
{
"created": "Mon, 22 Aug 2022 19:39:20 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Oct 2022 14:38:46 GMT",
"version": "v2"
}
] | 2022-10-21 | [
[
"Ongole",
"Geeth",
""
],
[
"Zhang",
"Hongchao",
""
],
[
"Zhu",
"Tao",
""
],
[
"Wang",
"Anzhong",
""
],
[
"Wang",
"Bin",
""
]
] | In this paper, we study a proposal put forward recently by Bodendorfer, Mele and M\"unch and Garc\'\i{}a-Quismondo and Marug\'an, in which the two polymerization parameters of spherically symmetric black hole spacetimes are the Dirac observables of the four-dimensional Ashtekar's variables. In this model, black and white hole horizons in general exist and naturally divide the spacetime into the external and internal regions. In the external region, the spacetime can be made asymptotically flat by properly choosing the dependence of the two polymerization parameters on the Ashtekar variables. Then, we find that the asymptotical behavior of the spacetime is universal, and, to the leading order, the curvature invariants are independent of the mass parameter $m$. For example, the Kretschmann scalar approaches zero as $K \simeq A_0r^{-4}$ asymptotically, where $A_0$ is generally a non-zero constant and independent of $m$, and $r$ the geometric radius of the two-spheres. In the internal region, all the physical quantities are finite, and the Schwarzschild black hole singularity is replaced by a transition surface whose radius is always finite and non-zero. The quantum gravitational effects are negligible near the black hole horizon for very massive black holes. However, the behavior of the spacetime across the transition surface is significantly different from all loop quantum black holes studied so far. In particular, the location of the maximum amplitude of the curvature scalars is displaced from the transition surface and depends on $m$, so does the maximum amplitude. In addition, the radius of the white hole is much smaller than that of the black hole, and its exact value sensitively depends on $m$, too. |
gr-qc/9210005 | Terry Goldman | T. Goldman, J. P\'erez-Mercader, Fred Cooper and Michael Martin Nieto | The Dark Matter Problem in Light of Quantum Gravity | 13 pages, LaTeX, (3 figues, not included) | null | 10.1016/0370-2693(92)91132-S | LA-UR-92-2642 | gr-qc astro-ph hep-ph | null | We show how, by considering the cumulative effect of tiny quantum
gravitational fluctuations over very large distances, it may be possible to:
($a$) reconcile nucleosynthesis bounds on the density parameter of the Universe
with the predictions of inflationary cosmology, and ($b$) reproduce the
inferred variation of the density parameter with distance. Our calculation can
be interpreted as a computation of the contribution of quantum gravitational
degrees of freedom to the (local) energy density of the Universe.
| [
{
"created": "Thu, 8 Oct 1992 03:47:44 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Goldman",
"T.",
""
],
[
"Pérez-Mercader",
"J.",
""
],
[
"Cooper",
"Fred",
""
],
[
"Nieto",
"Michael Martin",
""
]
] | We show how, by considering the cumulative effect of tiny quantum gravitational fluctuations over very large distances, it may be possible to: ($a$) reconcile nucleosynthesis bounds on the density parameter of the Universe with the predictions of inflationary cosmology, and ($b$) reproduce the inferred variation of the density parameter with distance. Our calculation can be interpreted as a computation of the contribution of quantum gravitational degrees of freedom to the (local) energy density of the Universe. |
2204.03093 | Etera R. Livine | Qian Chen, Etera R. Livine | Intertwiner Entanglement Excitation and Holonomy Operator | 35 pages | null | 10.1088/1361-6382/ac90aa | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the loop quantum gravity framework, spin network states carry entanglement
between quantum excitations of the geometry at different space points. This
intertwiner entanglement is gauge-invariant and comes from quantum
superposition of spins and intertwiners. Bipartite entanglement can be
interpreted as a witness of distance, while multipartite entanglement reflects
the curvature of the quantum geometry. The present work investigates how the
bipartite and multipartite intertwiner entanglement changes under the action of
the holonomy operator, which is the basic building block of loop quantum
gravity's dynamics. We reveal the relation between entanglement excitation and
the dispersion of the holonomy operator. This leads to a new interesting
connection between bulk geometry and boundary observables via the dynamics of
entanglement.
| [
{
"created": "Wed, 6 Apr 2022 21:15:35 GMT",
"version": "v1"
}
] | 2022-10-19 | [
[
"Chen",
"Qian",
""
],
[
"Livine",
"Etera R.",
""
]
] | In the loop quantum gravity framework, spin network states carry entanglement between quantum excitations of the geometry at different space points. This intertwiner entanglement is gauge-invariant and comes from quantum superposition of spins and intertwiners. Bipartite entanglement can be interpreted as a witness of distance, while multipartite entanglement reflects the curvature of the quantum geometry. The present work investigates how the bipartite and multipartite intertwiner entanglement changes under the action of the holonomy operator, which is the basic building block of loop quantum gravity's dynamics. We reveal the relation between entanglement excitation and the dispersion of the holonomy operator. This leads to a new interesting connection between bulk geometry and boundary observables via the dynamics of entanglement. |
2312.09622 | Alexey Smirnov | Alexey L. Smirnov | The initial data problem for a traversable wormhole with interacting
mouths | 9 pages, 2 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this study, we consider the time-symmetric initial data problem for GR
minimally coupled with a phantom scalar field and a Maxwell field. The main
focus is on initial data sets describing two interacting mouths of the same
traversable wormhole. These data sets are similar in many respects to the
Misner initial data with two black holes.
| [
{
"created": "Fri, 15 Dec 2023 09:04:24 GMT",
"version": "v1"
}
] | 2023-12-18 | [
[
"Smirnov",
"Alexey L.",
""
]
] | In this study, we consider the time-symmetric initial data problem for GR minimally coupled with a phantom scalar field and a Maxwell field. The main focus is on initial data sets describing two interacting mouths of the same traversable wormhole. These data sets are similar in many respects to the Misner initial data with two black holes. |
1611.03096 | Florian Hopfm\"uller | Florian Hopfm\"uller, Laurent Freidel | Gravity Degrees of Freedom on a Null Surface | 28 pages, 3 figures. Second version with minor edits | Phys. Rev. D 95, 104006 (2017) | 10.1103/PhysRevD.95.104006 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A canonical analysis for general relativity is performed on a null surface
without fixing the diffeomorphism gauge, and the canonical pairs of
configuration and momentum variables are derived. Next to the well-known spin-2
pair, also spin-1 and spin-0 pairs are identified. The boundary action for a
null boundary segment of spacetime is obtained, including terms on codimension
two corners.
| [
{
"created": "Wed, 9 Nov 2016 21:13:49 GMT",
"version": "v1"
},
{
"created": "Mon, 21 Nov 2016 17:29:04 GMT",
"version": "v2"
}
] | 2017-05-17 | [
[
"Hopfmüller",
"Florian",
""
],
[
"Freidel",
"Laurent",
""
]
] | A canonical analysis for general relativity is performed on a null surface without fixing the diffeomorphism gauge, and the canonical pairs of configuration and momentum variables are derived. Next to the well-known spin-2 pair, also spin-1 and spin-0 pairs are identified. The boundary action for a null boundary segment of spacetime is obtained, including terms on codimension two corners. |
1809.00868 | Sanjib Dey | Sumeet Chougule, Sanjib Dey, Behnam Pourhassan, Mir Faizal | BTZ black holes in massive gravity | 11 pages | Eur. Phys. J. C (2018) 78:685 | 10.1140/epjc/s10052-018-6172-7 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze certain aspects of BTZ black holes in massive theory of gravity.
The black hole solution is obtained by using the Vainshtein and dRGT mechanism,
which is asymptotically AdS with an electric charge. We study the Hawking
radiation using the tunneling formalism as well as analyze the black hole
chemistry for such system. Subsequently, we use the thermodynamic
pressure-volume diagram to explore the efficiency of the Carnot heat engine for
this system. Some of the important features arising from our solution include
the non-existence of quantum effects, critical Van der Walls behaviour, thermal
fluctuations and instabilities. Moreover, our solution violates the Reverse
Isoperimetric Inequality and, thus, the black hole is super-entropic, perhaps
which turns out to be the most interesting characteristics of the BTZ black
hole in massive gravity.
| [
{
"created": "Tue, 4 Sep 2018 10:05:06 GMT",
"version": "v1"
}
] | 2018-09-05 | [
[
"Chougule",
"Sumeet",
""
],
[
"Dey",
"Sanjib",
""
],
[
"Pourhassan",
"Behnam",
""
],
[
"Faizal",
"Mir",
""
]
] | We analyze certain aspects of BTZ black holes in massive theory of gravity. The black hole solution is obtained by using the Vainshtein and dRGT mechanism, which is asymptotically AdS with an electric charge. We study the Hawking radiation using the tunneling formalism as well as analyze the black hole chemistry for such system. Subsequently, we use the thermodynamic pressure-volume diagram to explore the efficiency of the Carnot heat engine for this system. Some of the important features arising from our solution include the non-existence of quantum effects, critical Van der Walls behaviour, thermal fluctuations and instabilities. Moreover, our solution violates the Reverse Isoperimetric Inequality and, thus, the black hole is super-entropic, perhaps which turns out to be the most interesting characteristics of the BTZ black hole in massive gravity. |
gr-qc/0702039 | Matthew Pitkin | The LIGO Scientific Collaboration: B. Abbott, et al, M. Kramer and A.
G. Lyne | Upper limits on gravitational wave emission from 78 radio pulsars | 21 pages, published in Phys. Rev. D, corrected GEO600 sensitvity
curve in Figure 1 | Phys.Rev.D76:042001,2007 | 10.1103/PhysRevD.76.042001 | LIGO-P060011-05-Z | gr-qc astro-ph | null | We present upper limits on the gravitational wave emission from 78 radio
pulsars based on data from the third and fourth science runs of the LIGO and
GEO600 gravitational wave detectors. The data from both runs have been combined
coherently to maximise sensitivity. For the first time pulsars within binary
(or multiple) systems have been included in the search by taking into account
the signal modulation due to their orbits. Our upper limits are therefore the
first measured for 56 of these pulsars. For the remaining 22, our results
improve on previous upper limits by up to a factor of 10. For example, our
tightest upper limit on the gravitational strain is 2.6e-25 for PSRJ1603-7202,
and the equatorial ellipticity of PSRJ2124-3358 is less than 10^{-6}.
Furthermore, our strain upper limit for the Crab pulsar is only 2.2 times
greater than the fiducial spin-down limit.
| [
{
"created": "Wed, 7 Feb 2007 14:53:58 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Apr 2007 10:47:08 GMT",
"version": "v2"
},
{
"created": "Wed, 27 Jun 2007 09:06:22 GMT",
"version": "v3"
},
{
"created": "Thu, 26 Jul 2007 14:31:54 GMT",
"version": "v4"
},
{
"created": "Fri, 12 Oct 2007 16:23:23 GMT",
"version": "v5"
}
] | 2008-11-26 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"Abbott",
"B.",
""
],
[
"Kramer",
"M.",
""
],
[
"Lyne",
"A. G.",
""
]
] | We present upper limits on the gravitational wave emission from 78 radio pulsars based on data from the third and fourth science runs of the LIGO and GEO600 gravitational wave detectors. The data from both runs have been combined coherently to maximise sensitivity. For the first time pulsars within binary (or multiple) systems have been included in the search by taking into account the signal modulation due to their orbits. Our upper limits are therefore the first measured for 56 of these pulsars. For the remaining 22, our results improve on previous upper limits by up to a factor of 10. For example, our tightest upper limit on the gravitational strain is 2.6e-25 for PSRJ1603-7202, and the equatorial ellipticity of PSRJ2124-3358 is less than 10^{-6}. Furthermore, our strain upper limit for the Crab pulsar is only 2.2 times greater than the fiducial spin-down limit. |
1404.2684 | Shinji Tsujikawa | Shinji Tsujikawa | The effective field theory of inflation/dark energy and the Horndeski
theory | 39 pages, no figures, lecture note for the 7th Aegean Summer School,
Paros, 23-28 September, 2013 | Lect.Notes Phys. 892 (2015) 97-136 | 10.1007/978-3-319-10070-8_4 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The effective field theory (EFT) of cosmological perturbations is a useful
framework to deal with the low-energy degrees of freedom present for inflation
and dark energy. We review the EFT for modified gravitational theories by
starting from the most general action in unitary gauge that involves the lapse
function and the three-dimensional geometric scalar quantities appearing in the
Arnowitt-Deser-Misner (ADM) formalism. Expanding the action up to quadratic
order in the perturbations and imposing conditions for the elimination of
spatial derivatives higher than second order, we obtain the Lagrangian of
curvature perturbations and gravitational waves with a single scalar degree of
freedom. The resulting second-order Lagrangian is exploited for computing the
scalar and tensor power spectra generated during inflation. We also show that
the most general scalar-tensor theory with second-order equations of
motion-Horndeski theory-belongs to the action of our general EFT framework and
that the background equations of motion in Horndeski theory can be conveniently
expressed in terms of three EFT parameters. Finally we study the equations of
matter density perturbations and the effective gravitational coupling for dark
energy models based on Horndeski theory, to confront the models with the
observations of large-scale structures and weak lensing.
| [
{
"created": "Thu, 10 Apr 2014 03:56:55 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Sep 2014 05:27:42 GMT",
"version": "v2"
}
] | 2014-11-13 | [
[
"Tsujikawa",
"Shinji",
""
]
] | The effective field theory (EFT) of cosmological perturbations is a useful framework to deal with the low-energy degrees of freedom present for inflation and dark energy. We review the EFT for modified gravitational theories by starting from the most general action in unitary gauge that involves the lapse function and the three-dimensional geometric scalar quantities appearing in the Arnowitt-Deser-Misner (ADM) formalism. Expanding the action up to quadratic order in the perturbations and imposing conditions for the elimination of spatial derivatives higher than second order, we obtain the Lagrangian of curvature perturbations and gravitational waves with a single scalar degree of freedom. The resulting second-order Lagrangian is exploited for computing the scalar and tensor power spectra generated during inflation. We also show that the most general scalar-tensor theory with second-order equations of motion-Horndeski theory-belongs to the action of our general EFT framework and that the background equations of motion in Horndeski theory can be conveniently expressed in terms of three EFT parameters. Finally we study the equations of matter density perturbations and the effective gravitational coupling for dark energy models based on Horndeski theory, to confront the models with the observations of large-scale structures and weak lensing. |
1602.03460 | Antoine Folacci | Yves D\'ecanini, Antoine Folacci and Mohamed Ould El Hadj | Waveforms in massive gravity and neutralization of giant black hole
ringings | v1:We complete our work on resonant excitation of BHs in massive
gravity (see arXiv:1401.0321[gr-qc] and arXiv:1402.2481[gr-qc]) and discuss
more particularly the observability of giant ringings. v2:With additional
remarks concerning waveforms corresponding to the weak instability regime.
(To appear in PRD). v3:Close to the published version | Phys. Rev. D 93, 124027 (2016) | 10.1103/PhysRevD.93.124027 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A distorted black hole radiates gravitational waves in order to settle down
in a smoother geometry. During that relaxation phase, a characteristic damped
ringing is generated. It can be theoretically constructed from both the black
hole quasinormal frequencies (which govern its oscillating behavior and its
decay) and the associated excitation factors (which determine intrinsically its
amplitude) by carefully taking into account the source of the distortion. In
the framework of massive gravity, the excitation factors of the Schwarzschild
black hole have an unexpected strong resonant behavior which, theoretically,
could lead to giant and slowly decaying ringings. If massive gravity is
relevant to physics, one can hope to observe these extraordinary ringings by
using the next generations of gravitational wave detectors. Indeed, they could
be generated by supermassive black holes if the graviton mass is not too small.
In fact, by focusing on the odd-parity $\ell=1$ mode of the Fierz-Pauli field,
we shall show here that such ringings are neutralized in waveforms due to (i)
the excitation of the quasibound states of the black hole and (ii) the
evanescent nature of the particular partial modes which could excite the
concerned quasinormal modes. Despite this, with observational consequences in
mind, it is interesting to note that the waveform amplitude is nevertheless
rather pronounced and slowly decaying (this effect is now due to the long-lived
quasibound states). It is worth noting also that, for very low values of the
graviton mass (corresponding to the weak instability regime for the black
hole), the waveform is now very clean and dominated by an ordinary ringing
which could be used as a signature of massive gravity.
| [
{
"created": "Wed, 10 Feb 2016 17:31:12 GMT",
"version": "v1"
},
{
"created": "Sat, 28 May 2016 06:02:45 GMT",
"version": "v2"
},
{
"created": "Tue, 14 Jun 2016 08:57:20 GMT",
"version": "v3"
}
] | 2016-06-22 | [
[
"Décanini",
"Yves",
""
],
[
"Folacci",
"Antoine",
""
],
[
"Hadj",
"Mohamed Ould El",
""
]
] | A distorted black hole radiates gravitational waves in order to settle down in a smoother geometry. During that relaxation phase, a characteristic damped ringing is generated. It can be theoretically constructed from both the black hole quasinormal frequencies (which govern its oscillating behavior and its decay) and the associated excitation factors (which determine intrinsically its amplitude) by carefully taking into account the source of the distortion. In the framework of massive gravity, the excitation factors of the Schwarzschild black hole have an unexpected strong resonant behavior which, theoretically, could lead to giant and slowly decaying ringings. If massive gravity is relevant to physics, one can hope to observe these extraordinary ringings by using the next generations of gravitational wave detectors. Indeed, they could be generated by supermassive black holes if the graviton mass is not too small. In fact, by focusing on the odd-parity $\ell=1$ mode of the Fierz-Pauli field, we shall show here that such ringings are neutralized in waveforms due to (i) the excitation of the quasibound states of the black hole and (ii) the evanescent nature of the particular partial modes which could excite the concerned quasinormal modes. Despite this, with observational consequences in mind, it is interesting to note that the waveform amplitude is nevertheless rather pronounced and slowly decaying (this effect is now due to the long-lived quasibound states). It is worth noting also that, for very low values of the graviton mass (corresponding to the weak instability regime for the black hole), the waveform is now very clean and dominated by an ordinary ringing which could be used as a signature of massive gravity. |
1703.01521 | Thilina Shihan Weerathunga | Thilina S. Weerathunga, Soumya D. Mohanty | Performance of Particle Swarm Optimization on the fully-coherent all-sky
search for gravitational waves from compact binary coalescences | 14 pages, 8 figures, Corrected typos, Eq. 40 has been corrected | Phys. Rev. D 95, 124030 (2017) | 10.1103/PhysRevD.95.124030 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Fully-coherent all-sky search for gravitational wave (GW) signals from the
coalescence of compact object binaries is a computationally expensive task.
Approximations, such as semi-coherent coincidence searches, are currently used
to circumvent the computational barrier with a concomitant loss in sensitivity.
We explore the effectiveness of Particle Swarm Optimization (PSO) in addressing
this problem. Our results, using a simulated network of detectors with initial
LIGO design sensitivities and a realistic signal strength, show that PSO can
successfully deliver a fully-coherent all-sky search with < 1/10 the number of
likelihood evaluations needed for a grid-based search.
| [
{
"created": "Sat, 4 Mar 2017 21:14:55 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Mar 2017 05:37:18 GMT",
"version": "v2"
},
{
"created": "Mon, 1 May 2017 23:21:55 GMT",
"version": "v3"
}
] | 2017-06-21 | [
[
"Weerathunga",
"Thilina S.",
""
],
[
"Mohanty",
"Soumya D.",
""
]
] | Fully-coherent all-sky search for gravitational wave (GW) signals from the coalescence of compact object binaries is a computationally expensive task. Approximations, such as semi-coherent coincidence searches, are currently used to circumvent the computational barrier with a concomitant loss in sensitivity. We explore the effectiveness of Particle Swarm Optimization (PSO) in addressing this problem. Our results, using a simulated network of detectors with initial LIGO design sensitivities and a realistic signal strength, show that PSO can successfully deliver a fully-coherent all-sky search with < 1/10 the number of likelihood evaluations needed for a grid-based search. |
0801.2134 | Bahram Mashhoon | Bahram Mashhoon | Spin-Gravity Coupling | 10 pages, invited paper presented at the Mathisson Conference (17-20
October 2007, Warsaw, Poland), to appear in Acta Phys. Pol. B | Acta Phys.Polon.Supp.1:113-122,2008 | null | null | gr-qc astro-ph hep-th | null | Mathisson's spin-gravity coupling and its Larmor-equivalent interaction,
namely, the spin-rotation coupling are discussed. The study of the latter leads
to a critical examination of the basic role of locality in relativistic
physics. The nonlocal theory of accelerated systems is outlined and some of its
implications are described.
| [
{
"created": "Mon, 14 Jan 2008 18:59:33 GMT",
"version": "v1"
}
] | 2009-02-10 | [
[
"Mashhoon",
"Bahram",
""
]
] | Mathisson's spin-gravity coupling and its Larmor-equivalent interaction, namely, the spin-rotation coupling are discussed. The study of the latter leads to a critical examination of the basic role of locality in relativistic physics. The nonlocal theory of accelerated systems is outlined and some of its implications are described. |
2304.10422 | Bing Tang | Jiayu Xie, Jie Wang, Bing Tang | Circular motion and chaos bound of a charged particle near charged 4D
Einstein-Gauss-Bonnet-AdS black holes | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the circular motion and chaos bound of a charged particle near
4D charged AdS black holes in Einstein-Gauss-Bonnet gravity theory. By means of
the Jacobian matrix, the analytical form of the Lyapunov exponent of the
charged particle is constructed, which satisfies the upper bound when it is on
the event horizon. By further expanding the Lyapunov exponent near the horizon
and investigating a 4D charged Einstein-Gauss-Bonnet-AdS black hole with
different Gauss-Bonnet coupling constant, we find that it has some specific
values to determine whether a violation of chaos bound. Besides, we find that
in contrast to the static equilibrium, the circular motion of charged particle
can have a larger Lyapunov exponent due to the existence of angular momentum.
Moreover, we show that the black hole gets closer to the extremal state as the
Gauss-Bonnet coupling constant increases, and the bound is more easily
violated. In addition, the range of particle charge that may violate the
chaotic bound are found for different Gauss-Bonnet coupling constants. The
results show that as the GB coupling parameter increases, the value of particle
charge required to satisfy the violation of the chaos bound is even smaller.
| [
{
"created": "Thu, 20 Apr 2023 16:11:04 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Jun 2023 15:51:52 GMT",
"version": "v2"
}
] | 2023-06-16 | [
[
"Xie",
"Jiayu",
""
],
[
"Wang",
"Jie",
""
],
[
"Tang",
"Bing",
""
]
] | We investigate the circular motion and chaos bound of a charged particle near 4D charged AdS black holes in Einstein-Gauss-Bonnet gravity theory. By means of the Jacobian matrix, the analytical form of the Lyapunov exponent of the charged particle is constructed, which satisfies the upper bound when it is on the event horizon. By further expanding the Lyapunov exponent near the horizon and investigating a 4D charged Einstein-Gauss-Bonnet-AdS black hole with different Gauss-Bonnet coupling constant, we find that it has some specific values to determine whether a violation of chaos bound. Besides, we find that in contrast to the static equilibrium, the circular motion of charged particle can have a larger Lyapunov exponent due to the existence of angular momentum. Moreover, we show that the black hole gets closer to the extremal state as the Gauss-Bonnet coupling constant increases, and the bound is more easily violated. In addition, the range of particle charge that may violate the chaotic bound are found for different Gauss-Bonnet coupling constants. The results show that as the GB coupling parameter increases, the value of particle charge required to satisfy the violation of the chaos bound is even smaller. |
1604.07306 | Lavinia Heisenberg | Lavinia Heisenberg and Alexandre Refregier | Cosmology in massive gravity with effective composite metric | 31 pages, 6 figures | null | 10.1088/1475-7516/2016/09/020 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper is dedicated to scrutinizing the cosmology in massive gravity. A
matter field of the dark sector is coupled to an effective composite metric
while a standard matter field couples to the dynamical metric in the usual way.
For this purpose, we study the dynamical system of cosmological solutions by
using phase analysis, which provides an overview of the class of cosmological
solutions in this setup. This also permits us to study the critical points of
the cosmological equations together with their stability. We show the presence
of stable attractor de Sitter critical points relevant to the late-time cosmic
acceleration. Furthermore, we study the tensor, vector and scalar perturbations
in the presence of standard matter fields and obtain the conditions for the
absence of ghost and gradient instabilities. Hence, massive gravity in the
presence of the effective composite metric can accommodate interesting dark
energy phenomenology, that can be observationally distinguished from the
standard model according to the expansion history and cosmic growth.
| [
{
"created": "Mon, 25 Apr 2016 15:16:40 GMT",
"version": "v1"
}
] | 2016-09-21 | [
[
"Heisenberg",
"Lavinia",
""
],
[
"Refregier",
"Alexandre",
""
]
] | This paper is dedicated to scrutinizing the cosmology in massive gravity. A matter field of the dark sector is coupled to an effective composite metric while a standard matter field couples to the dynamical metric in the usual way. For this purpose, we study the dynamical system of cosmological solutions by using phase analysis, which provides an overview of the class of cosmological solutions in this setup. This also permits us to study the critical points of the cosmological equations together with their stability. We show the presence of stable attractor de Sitter critical points relevant to the late-time cosmic acceleration. Furthermore, we study the tensor, vector and scalar perturbations in the presence of standard matter fields and obtain the conditions for the absence of ghost and gradient instabilities. Hence, massive gravity in the presence of the effective composite metric can accommodate interesting dark energy phenomenology, that can be observationally distinguished from the standard model according to the expansion history and cosmic growth. |
1205.6751 | W. G. Unruh | W. G. Unruh | Irrotational, two-dimensional Surface waves in fluids | 14 pages. To appear in Analog Gravity-- Proceedings of the Como
Summer School 2011 ed D. Faccio et al, Springer-Velag | null | 10.1007/978-3-319-00266-8_4 | null | gr-qc physics.flu-dyn | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The equations for waves on the surface of an irrotational incompressible
fluid are derived in the coordinates of the velocity potential/stream function.
The low frequency shallow water approximation for these waves is derived for a
varying bottom topography. Most importantly, the conserved norm for the surface
waves is derived, important for quantisation of these waves and their use in
analog models for black holes.
| [
{
"created": "Wed, 30 May 2012 16:49:13 GMT",
"version": "v1"
}
] | 2015-06-05 | [
[
"Unruh",
"W. G.",
""
]
] | The equations for waves on the surface of an irrotational incompressible fluid are derived in the coordinates of the velocity potential/stream function. The low frequency shallow water approximation for these waves is derived for a varying bottom topography. Most importantly, the conserved norm for the surface waves is derived, important for quantisation of these waves and their use in analog models for black holes. |
1304.1899 | Christian Corda Prof. | Christian Corda | Time-Dependent Schrodinger Equation for Black Hole Evaporation: no
Information Loss | 18 pages, definitive version accepted for publication in Annals of
Physics. Comments are welcome. The results in arXiv:1210.7747 have been
partially reviewed. Dedicated to the memory of the latter IFM Secretary
Franco Pettini | Ann. Phys. 353, 71 (2015) | 10.1016/j.aop.2014.11.002 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In 1976 S. Hawking claimed that "Because part of the information about the
state of the system is lost down the hole, the final situation is represented
by a density matrix rather than a pure quantum state" (Verbatim from ref. 2).
This was the starting point of the popular "black hole (BH) information
paradox". In a series of papers, together with collaborators, we naturally
interpreted BH quasi-normal modes (QNMs) in terms of quantum levels discussing
a model of excited BH somewhat similar to the historical semi-classical Bohr
model of the structure of a hydrogen atom. Here we explicitly write down, for
the same model, a time dependent Schr\"odinger equation for the system composed
by Hawking radiation and BH QNMs. The physical state and the correspondent wave
function are written in terms of an unitary evolution matrix instead of a
density matrix. Thus, the final state results to be a pure quantum state
instead of a mixed one. Hence, Hawking's claim is falsified because BHs result
to be well defined quantum mechanical systems, having ordered, discrete quantum
spectra, which respect 't Hooft's assumption that Schr\"oedinger equations can
be used universally for all dynamics in the universe. As a consequence,
information comes out in BH evaporation in terms of pure states in an unitary
time dependent evolution. In Section 4 of this paper we show that the present
approach permits also to solve the entanglement problem connected with the
information paradox.
| [
{
"created": "Sat, 6 Apr 2013 15:06:53 GMT",
"version": "v1"
},
{
"created": "Wed, 22 May 2013 16:35:17 GMT",
"version": "v2"
},
{
"created": "Thu, 27 Jun 2013 12:02:57 GMT",
"version": "v3"
},
{
"created": "Wed, 9 Apr 2014 15:59:21 GMT",
"version": "v4"
},
{
"created": "Thu, 6 Nov 2014 06:37:57 GMT",
"version": "v5"
}
] | 2014-12-04 | [
[
"Corda",
"Christian",
""
]
] | In 1976 S. Hawking claimed that "Because part of the information about the state of the system is lost down the hole, the final situation is represented by a density matrix rather than a pure quantum state" (Verbatim from ref. 2). This was the starting point of the popular "black hole (BH) information paradox". In a series of papers, together with collaborators, we naturally interpreted BH quasi-normal modes (QNMs) in terms of quantum levels discussing a model of excited BH somewhat similar to the historical semi-classical Bohr model of the structure of a hydrogen atom. Here we explicitly write down, for the same model, a time dependent Schr\"odinger equation for the system composed by Hawking radiation and BH QNMs. The physical state and the correspondent wave function are written in terms of an unitary evolution matrix instead of a density matrix. Thus, the final state results to be a pure quantum state instead of a mixed one. Hence, Hawking's claim is falsified because BHs result to be well defined quantum mechanical systems, having ordered, discrete quantum spectra, which respect 't Hooft's assumption that Schr\"oedinger equations can be used universally for all dynamics in the universe. As a consequence, information comes out in BH evaporation in terms of pure states in an unitary time dependent evolution. In Section 4 of this paper we show that the present approach permits also to solve the entanglement problem connected with the information paradox. |
gr-qc/9806053 | Alex Kaganovich | E.I.Guendelman and A.B.Kaganovich | Dominance of a Dynamical Measure and Disappearance of the Cosmological
Constant | 10 pages | null | null | null | gr-qc | null | We consider an action which consists of two terms: the first S_{1}=\int
L_{1}\Phi d^{4}x and the second S_{2}=\int L_{2}\sqrt{-g}d^{4}x where \Phi is a
measure which has to be determined dynamically. S_{1} satisfies the requirement
that the transformation L_{1}\to L_{1}+const does not effect equations of
motion. In the first order formalism, a constraint appears which allows to
solve \chi =\Phi/\sqrt{-g}. Then, in a true vacuum state (TVS), \chi\to\infty
and in the conformal Einstein frame no singularities are present, the energy
density of TVS is zero without fine tuning of any scalar potential in S_{1} or
S_{2}. When considering only a linear potential for a scalar field \phi in
S_{1}, the continuous symmetry \phi\to\phi+const is respected. Surprisingly, in
this case SSB takes place while no massless ("Goldstone") boson appears.
| [
{
"created": "Thu, 11 Jun 1998 07:45:29 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Guendelman",
"E. I.",
""
],
[
"Kaganovich",
"A. B.",
""
]
] | We consider an action which consists of two terms: the first S_{1}=\int L_{1}\Phi d^{4}x and the second S_{2}=\int L_{2}\sqrt{-g}d^{4}x where \Phi is a measure which has to be determined dynamically. S_{1} satisfies the requirement that the transformation L_{1}\to L_{1}+const does not effect equations of motion. In the first order formalism, a constraint appears which allows to solve \chi =\Phi/\sqrt{-g}. Then, in a true vacuum state (TVS), \chi\to\infty and in the conformal Einstein frame no singularities are present, the energy density of TVS is zero without fine tuning of any scalar potential in S_{1} or S_{2}. When considering only a linear potential for a scalar field \phi in S_{1}, the continuous symmetry \phi\to\phi+const is respected. Surprisingly, in this case SSB takes place while no massless ("Goldstone") boson appears. |
1710.06605 | Mohammad Vahid Takook | M. V. Takook | Linear Gravity in de Sitter universe | 13 pages, | Iranian Physical Journal, 3-1, 1-8 (2009) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give in this paper an explicit construction of the covariant quantization
of the rank-two massless tensor field on de Sitter space (linear covariant
quantum gravity on a de Sitter background). The main ingredient of the
construction is an indecomposable representation of de Sitter group. We here
make the choice of a specific simple gauge fixing. We show that our gauge
fixing eliminates any infrared divergence in the two-point function for the
traceless part of this field. But it is not possible to do the same for the
pure trace part (conformal sector). We describe the related Krein space
structure and covariant field operators. This work is in the continuation of
our previous ones concerning the massless minimally coupled scalar fields and
the massive tensor field on de Sitter.
| [
{
"created": "Wed, 18 Oct 2017 07:40:02 GMT",
"version": "v1"
}
] | 2017-10-19 | [
[
"Takook",
"M. V.",
""
]
] | We give in this paper an explicit construction of the covariant quantization of the rank-two massless tensor field on de Sitter space (linear covariant quantum gravity on a de Sitter background). The main ingredient of the construction is an indecomposable representation of de Sitter group. We here make the choice of a specific simple gauge fixing. We show that our gauge fixing eliminates any infrared divergence in the two-point function for the traceless part of this field. But it is not possible to do the same for the pure trace part (conformal sector). We describe the related Krein space structure and covariant field operators. This work is in the continuation of our previous ones concerning the massless minimally coupled scalar fields and the massive tensor field on de Sitter. |
1607.03505 | Farook Rahaman | I. Radinschi, Farook Rahaman, Th. Grammenos, Sayeedul Islam | Einstein and M{\o}ller energy-momentum complexes for a new regular black
hole solution with a nonlinear electrodynamics source | New figures and minor changes. Accepted in Adv.High.Ener.Phys | null | 10.1155/2016/904930 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A study about the energy and momentum distributions of a new charged regular
black hole solution with a nonlinear electrodynamics source is presented. The
energy and momentum are calculated using the Einstein and M{\o}ller
energy-momentum complexes. The results show that in both pseudotensorial
prescriptions the expressions for the energy of the gravitational background
depend on the mass $M$ and the charge $q$ of the black hole, an additional
factor $\beta $ coming from the spacetime metric considered, and the radial
coordinate $r$, while in both prescriptions all the momenta vanish. Further, it
is pointed out that in some limiting and particular cases the two complexes
yield the same expression for the energy distribution as that obtained in the
relevant literature for the Schwarzschild black hole solution.
| [
{
"created": "Thu, 30 Jun 2016 15:38:36 GMT",
"version": "v1"
},
{
"created": "Fri, 30 Sep 2016 08:31:40 GMT",
"version": "v2"
}
] | 2017-04-26 | [
[
"Radinschi",
"I.",
""
],
[
"Rahaman",
"Farook",
""
],
[
"Grammenos",
"Th.",
""
],
[
"Islam",
"Sayeedul",
""
]
] | A study about the energy and momentum distributions of a new charged regular black hole solution with a nonlinear electrodynamics source is presented. The energy and momentum are calculated using the Einstein and M{\o}ller energy-momentum complexes. The results show that in both pseudotensorial prescriptions the expressions for the energy of the gravitational background depend on the mass $M$ and the charge $q$ of the black hole, an additional factor $\beta $ coming from the spacetime metric considered, and the radial coordinate $r$, while in both prescriptions all the momenta vanish. Further, it is pointed out that in some limiting and particular cases the two complexes yield the same expression for the energy distribution as that obtained in the relevant literature for the Schwarzschild black hole solution. |
1103.0783 | Ghazal Geshnizjani | Jose Tomas Galvez Ghersi, Ghazal Geshnizjani, Federico Piazza, Sarah
Shandera | Eternal inflation and a thermodynamic treatment of Einstein's equations | 1 figure, matches the published version in JCAP | JCAP 1106:005,2011 | 10.1088/1475-7516/2011/06/005 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In pursuing the intriguing resemblance of the Einstein equations to
thermodynamic equations, most sharply seen in systems possessing horizons, we
suggest that eternal inflation of the stochastic type may be a fruitful
phenomenon to explore. We develop a thermodynamic first law for quasi-de Sitter
space, valid on the horizon of a single observer's Hubble patch and explore
consistancy with previous proposals for horizons of various types in dynamic
and static situations. We use this framework to demonstrate that for the local
observer fluctuations of the type necessary for stochastic eternal inflation
fall within the regime where the thermodynamic approach is believed to apply.
This scenario is interesting because of suggestive parallels to black hole
evaporation.
| [
{
"created": "Thu, 3 Mar 2011 21:04:50 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Sep 2011 21:46:31 GMT",
"version": "v2"
}
] | 2011-10-03 | [
[
"Ghersi",
"Jose Tomas Galvez",
""
],
[
"Geshnizjani",
"Ghazal",
""
],
[
"Piazza",
"Federico",
""
],
[
"Shandera",
"Sarah",
""
]
] | In pursuing the intriguing resemblance of the Einstein equations to thermodynamic equations, most sharply seen in systems possessing horizons, we suggest that eternal inflation of the stochastic type may be a fruitful phenomenon to explore. We develop a thermodynamic first law for quasi-de Sitter space, valid on the horizon of a single observer's Hubble patch and explore consistancy with previous proposals for horizons of various types in dynamic and static situations. We use this framework to demonstrate that for the local observer fluctuations of the type necessary for stochastic eternal inflation fall within the regime where the thermodynamic approach is believed to apply. This scenario is interesting because of suggestive parallels to black hole evaporation. |
0811.0299 | Mikhail Smolyakov | Mikhail N. Smolyakov | Submanifolds in space-time with unphysical extra dimensions, cosmology
and warped brane world models | 4 pages, LaTeX, equations (19) and (20) corrected | Class.Quant.Grav.25:238003,2008; Erratum-ibid.27:109801,2010 | 10.1088/0264-9381/25/23/238003 10.1088/0264-9381/27/10/109801 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The explicit coordinate transformations which show the equivalence between a
four-dimensional spatially flat cosmology and an appropriate submanifold in the
flat five-dimensional Minkowski space-time are presented. Analogous procedure
is made for the case of five-dimensional warped brane world models. Several
examples are presented.
| [
{
"created": "Mon, 3 Nov 2008 13:59:25 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Apr 2010 23:46:48 GMT",
"version": "v2"
}
] | 2010-04-29 | [
[
"Smolyakov",
"Mikhail N.",
""
]
] | The explicit coordinate transformations which show the equivalence between a four-dimensional spatially flat cosmology and an appropriate submanifold in the flat five-dimensional Minkowski space-time are presented. Analogous procedure is made for the case of five-dimensional warped brane world models. Several examples are presented. |
1805.08644 | Cong Zhang | Cong Zhang, Jerzy Lewandowski, Yongge Ma | Towards the self-adjointness of a Hamiltonian operator in loop quantum
gravity | null | Phys. Rev. D 98, 086014 (2018) | 10.1103/PhysRevD.98.086014 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Although the physical Hamiltonian operator can be constructed in the
deparameterized model of loop quantum gravity coupled to a scalar field, its
property is still unknown. This open issue is attacked in this paper by
considering an operator $\hat{H}_v$ representing the square of the physical
Hamiltonian operator acting nontrivially on two-valent spin networks. The
Hilbert space $\mathcal{H}_v$ preserved by the graphing changing operator
$\hat{H}_v$ is consist of spin networks with a single two-valent non-degenerate
vertex. The matrix element of $\hat{H}_v$ are explicitly worked out in a
suitable basis. It turns out that the operator $\hat{H}_v$ is essentially
self-adjoint, which implies a well-defined physical Hamiltonian operator in
$\mathcal{H}_v$ for the deparameterized model.
| [
{
"created": "Tue, 22 May 2018 14:49:40 GMT",
"version": "v1"
},
{
"created": "Wed, 23 May 2018 07:32:38 GMT",
"version": "v2"
},
{
"created": "Sun, 28 Oct 2018 14:21:32 GMT",
"version": "v3"
},
{
"created": "Wed, 5 Jun 2019 14:26:30 GMT",
"version": "v4"
},
{
"created": "Sun, 15 Dec 2019 14:59:48 GMT",
"version": "v5"
}
] | 2019-12-17 | [
[
"Zhang",
"Cong",
""
],
[
"Lewandowski",
"Jerzy",
""
],
[
"Ma",
"Yongge",
""
]
] | Although the physical Hamiltonian operator can be constructed in the deparameterized model of loop quantum gravity coupled to a scalar field, its property is still unknown. This open issue is attacked in this paper by considering an operator $\hat{H}_v$ representing the square of the physical Hamiltonian operator acting nontrivially on two-valent spin networks. The Hilbert space $\mathcal{H}_v$ preserved by the graphing changing operator $\hat{H}_v$ is consist of spin networks with a single two-valent non-degenerate vertex. The matrix element of $\hat{H}_v$ are explicitly worked out in a suitable basis. It turns out that the operator $\hat{H}_v$ is essentially self-adjoint, which implies a well-defined physical Hamiltonian operator in $\mathcal{H}_v$ for the deparameterized model. |
1109.5821 | Luca Fabbri | Stefano Vignolo, Luca Fabbri | Spin fluids in Bianchi-I f(R)-cosmology with torsion | 18 pages | Int. J. Geom. Meth. Mod. Phys. 9, 1250054 (2012) | 10.1142/S0219887812500545 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study Weyssenhoff spin fluids in Bianchi type-I cosmological models,
within the framework of torsional f(R)-gravity; the resulting field equations
are derived and discussed in both Jordan and Einstein frames, clarifying the
role played by the spin and the non-linearity of the gravitational Lagrangian
f(R) in generating the torsional dynamical contributions. The general
conservation laws holding for f(R)-gravity with torsion are employed to provide
the conditions needed to ensure the preservation of the Hamiltonian constraint
and the consequent correct formulation of the associated initial value problem.
Examples are eventually given.
| [
{
"created": "Tue, 27 Sep 2011 09:48:31 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Jul 2012 07:49:05 GMT",
"version": "v2"
}
] | 2012-08-01 | [
[
"Vignolo",
"Stefano",
""
],
[
"Fabbri",
"Luca",
""
]
] | We study Weyssenhoff spin fluids in Bianchi type-I cosmological models, within the framework of torsional f(R)-gravity; the resulting field equations are derived and discussed in both Jordan and Einstein frames, clarifying the role played by the spin and the non-linearity of the gravitational Lagrangian f(R) in generating the torsional dynamical contributions. The general conservation laws holding for f(R)-gravity with torsion are employed to provide the conditions needed to ensure the preservation of the Hamiltonian constraint and the consequent correct formulation of the associated initial value problem. Examples are eventually given. |
2311.08344 | Ernesto Contreras | A. Rueda, E. Contreras | Geodesic analysis and steady accretion on a traversable wormhole | null | Annals of Physics 459, 169540 (2023) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we analyze the behavior of light and matter as they pass near
and through a traversable wormhole. In particular, we study the trajectories of
massive and massless particles and the dust accretion around a traversable
wormhole previously reported in Eur. Phys. J. C \textbf{82} (2022) no.7, 605.
For massive particles, we integrate the trajectory equation for ingoing and
outgoing geodesics and classify the orbits of particles scattered by the
wormhole in accordance with their asymptotic behavior far from the throat. We
represent all the time--like trajectories in an embedding surface where it is
shown explicitly the trajectories of i) particles that deviate from the throat
and remain in the same universe, ii) particles that traverse the wormhole to
another universe, and iii) particles that get trapped in the wormhole in
unstable circular orbits. For the massless particles, we numerically integrate
the trajectory equation to show the ray-tracing around the wormhole specifying
the particles that traverse the wormhole and those that are only deviated by
the throat. For the study of accretion, we consider the steady and spherically
symmetric accretion of dust. Our results show that the wormhole parameters can
significantly affect the behavior of light and matter near the wormhole. Some
comparisons with the behavior of matter around black holes are made.
| [
{
"created": "Tue, 14 Nov 2023 17:40:57 GMT",
"version": "v1"
}
] | 2023-11-15 | [
[
"Rueda",
"A.",
""
],
[
"Contreras",
"E.",
""
]
] | In this work, we analyze the behavior of light and matter as they pass near and through a traversable wormhole. In particular, we study the trajectories of massive and massless particles and the dust accretion around a traversable wormhole previously reported in Eur. Phys. J. C \textbf{82} (2022) no.7, 605. For massive particles, we integrate the trajectory equation for ingoing and outgoing geodesics and classify the orbits of particles scattered by the wormhole in accordance with their asymptotic behavior far from the throat. We represent all the time--like trajectories in an embedding surface where it is shown explicitly the trajectories of i) particles that deviate from the throat and remain in the same universe, ii) particles that traverse the wormhole to another universe, and iii) particles that get trapped in the wormhole in unstable circular orbits. For the massless particles, we numerically integrate the trajectory equation to show the ray-tracing around the wormhole specifying the particles that traverse the wormhole and those that are only deviated by the throat. For the study of accretion, we consider the steady and spherically symmetric accretion of dust. Our results show that the wormhole parameters can significantly affect the behavior of light and matter near the wormhole. Some comparisons with the behavior of matter around black holes are made. |
2310.16799 | Andrew Laeuger | Andrew Laeuger, Brian Seymour, Yanbei Chen, Hang Yu | Measuring Supermassive Black Hole Properties via Gravitational Radiation
from Eccentrically Orbiting Stellar Mass Black Hole Binaries | 12 pages (main text excluding references and appendices), 11 figures,
submitted to PRD | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | There may exist stellar-mass binary black holes (BBH) which merge while
orbiting nearby a supermassive black hole (SMBH). In such a triple system, the
SMBH will modulate the gravitational waveform of the BBH through orbital
Doppler shift and de Sitter precession of the angular momentum. Future
space-based GW observatories focused on the milli- and decihertz band will be
uniquely poised to observe these waveform modulations, as the GW frequency from
stellar-mass BBHs varies slowly in this band while modulation effects
accumulate. In this work, we apply the Fisher information matrix formalism to
estimate how well space-borne GW detectors can measure properties of BBH+SMBH
hierarchical triples using the GW from orbiting BBH. We extend previous work by
considering the more realistic case of an eccentric orbit around the SMBH, and
notably include the effects of orbital pericenter precession. We find that for
detector concepts such as LISA, B-DECIGO, and TianGO, we can extract the SMBH
mass and semimajor axis of the orbit with a fractional uncertainty below the
0.1% level over a wide range of triple system parameters. Furthermore, we find
that the effects of pericenter precession and orbital eccentricity
significantly improve our ability to measure this system. We also find that
while LISA could measure these systems, the decihertz detector concepts
B-DECIGO and TianGO would enable better sensitivity to the triple's parameters.
| [
{
"created": "Wed, 25 Oct 2023 17:29:19 GMT",
"version": "v1"
}
] | 2023-10-26 | [
[
"Laeuger",
"Andrew",
""
],
[
"Seymour",
"Brian",
""
],
[
"Chen",
"Yanbei",
""
],
[
"Yu",
"Hang",
""
]
] | There may exist stellar-mass binary black holes (BBH) which merge while orbiting nearby a supermassive black hole (SMBH). In such a triple system, the SMBH will modulate the gravitational waveform of the BBH through orbital Doppler shift and de Sitter precession of the angular momentum. Future space-based GW observatories focused on the milli- and decihertz band will be uniquely poised to observe these waveform modulations, as the GW frequency from stellar-mass BBHs varies slowly in this band while modulation effects accumulate. In this work, we apply the Fisher information matrix formalism to estimate how well space-borne GW detectors can measure properties of BBH+SMBH hierarchical triples using the GW from orbiting BBH. We extend previous work by considering the more realistic case of an eccentric orbit around the SMBH, and notably include the effects of orbital pericenter precession. We find that for detector concepts such as LISA, B-DECIGO, and TianGO, we can extract the SMBH mass and semimajor axis of the orbit with a fractional uncertainty below the 0.1% level over a wide range of triple system parameters. Furthermore, we find that the effects of pericenter precession and orbital eccentricity significantly improve our ability to measure this system. We also find that while LISA could measure these systems, the decihertz detector concepts B-DECIGO and TianGO would enable better sensitivity to the triple's parameters. |
1307.7859 | Amalaya Khurshudyan | Martiros Khurshudyan and Amalya Khurshudyan | Interacting varying Ghost Dark energy models in General Relativity | null | null | 10.1007/s10509-015-2341-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by recent developments in Cosmology we would like to consider an
extension of the Ghost DE which we will call as varying Ghost DE. Ghost DE like
other models was introduced recently as a possible way to explain accelerated
expansion of the Universe. For the phenomenological origin of the varying Ghost
dark energy in our Universe we can suggest an existence of some unknown
dynamics between the Ghost Dark energy and a fluid which evaporated completely
making sense of the proposed effect. Moreover, we assume that this was in the
epochs and scales which are unreachable by nowadays experiments, like in very
early Universe. In this study we will investigate the model for cosmological
validity. We will apply observational and causality constraints to illuminate
physically correct behavior of the model from the phenomenological one. We saw
that an interaction between the varying Ghost DE and cold DM~(CDM) also
provides a solution to the cosmological coincidence problem. And we found that
the Ghost DE behaves as a matter like fluid in early Universe.
| [
{
"created": "Tue, 30 Jul 2013 08:01:55 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Nov 2014 11:27:05 GMT",
"version": "v2"
}
] | 2015-07-28 | [
[
"Khurshudyan",
"Martiros",
""
],
[
"Khurshudyan",
"Amalya",
""
]
] | Motivated by recent developments in Cosmology we would like to consider an extension of the Ghost DE which we will call as varying Ghost DE. Ghost DE like other models was introduced recently as a possible way to explain accelerated expansion of the Universe. For the phenomenological origin of the varying Ghost dark energy in our Universe we can suggest an existence of some unknown dynamics between the Ghost Dark energy and a fluid which evaporated completely making sense of the proposed effect. Moreover, we assume that this was in the epochs and scales which are unreachable by nowadays experiments, like in very early Universe. In this study we will investigate the model for cosmological validity. We will apply observational and causality constraints to illuminate physically correct behavior of the model from the phenomenological one. We saw that an interaction between the varying Ghost DE and cold DM~(CDM) also provides a solution to the cosmological coincidence problem. And we found that the Ghost DE behaves as a matter like fluid in early Universe. |
1111.5558 | Gonzalo Olmo | Gonzalo J. Olmo | Palatini approach to bouncing cosmologies and DSR-like effects | 4 pages. Proceedings of Loops'11, Madrid. To appear in Journal of
Physics: Conference Series (JPCS) | null | 10.1088/1742-6596/360/1/012034 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that a quadratic gravitational Lagrangian in the Palatini
formulation is able to capture different aspects of quantum gravity
phenomenology in a single framework. In particular, in this theory field
excitations propagating with different energy-densities perceive different
background metrics, a fundamental characteristic of the DSR and Rainbow Gravity
approaches. This theory, however, avoids the so-called soccer ball problem.
Also, the resulting isotropic and anisotropic cosmologies are free from the big
bang singularity. This singularity avoidance occurs non-perturbatively and
shares some similitudes with the effective dynamics of loop quantum cosmology.
| [
{
"created": "Wed, 23 Nov 2011 17:14:18 GMT",
"version": "v1"
}
] | 2015-06-03 | [
[
"Olmo",
"Gonzalo J.",
""
]
] | It is shown that a quadratic gravitational Lagrangian in the Palatini formulation is able to capture different aspects of quantum gravity phenomenology in a single framework. In particular, in this theory field excitations propagating with different energy-densities perceive different background metrics, a fundamental characteristic of the DSR and Rainbow Gravity approaches. This theory, however, avoids the so-called soccer ball problem. Also, the resulting isotropic and anisotropic cosmologies are free from the big bang singularity. This singularity avoidance occurs non-perturbatively and shares some similitudes with the effective dynamics of loop quantum cosmology. |
2104.05250 | Aurore Blelly | Aurore Blelly and J\'er\^ome Bobin and Herv\'e Moutarde | Sparse data inpainting for the recovery of Galactic-binary gravitational
wave signals from gapped data | null | null | 10.1093/mnras/stab3314 | null | gr-qc astro-ph.HE astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The forthcoming space-based gravitational wave observatory LISA will open a
new window for the measurement of galactic binaries, which will deliver
unprecedented information about these systems. However, the detection of
galactic binary gravitational wave signals is challenged by the presence of
gaps in the data. Whether being planned or not, gapped data dramatically reduce
our ability to detect faint signals and the risk of misdetection soars.
Inspired by advances in signal processing, we introduce a \nonparametric
inpainting algorithm based on the sparse representation of the galactic binary
signal in the Fourier domain. In contrast to traditional inpainting approaches,
noise statistics are known theoretically on ungapped measurements only. This
calls for the joint recovery of both the ungapped noise and the galactic binary
signal. We thoroughly show that sparse inpainting yields an accurate estimation
of the gravitational imprint of the galactic binaries. Additionally, we
highlight that the proposed algorithm produces a statistically consistent
ungapped noise estimate. We further evaluate the performances of the proposed
inpainting methods to recover the gravitational wave signal on a simple example
involving verification galactic binaries recently proposed in LISA data
challenges.
| [
{
"created": "Mon, 12 Apr 2021 07:34:43 GMT",
"version": "v1"
}
] | 2021-11-24 | [
[
"Blelly",
"Aurore",
""
],
[
"Bobin",
"Jérôme",
""
],
[
"Moutarde",
"Hervé",
""
]
] | The forthcoming space-based gravitational wave observatory LISA will open a new window for the measurement of galactic binaries, which will deliver unprecedented information about these systems. However, the detection of galactic binary gravitational wave signals is challenged by the presence of gaps in the data. Whether being planned or not, gapped data dramatically reduce our ability to detect faint signals and the risk of misdetection soars. Inspired by advances in signal processing, we introduce a \nonparametric inpainting algorithm based on the sparse representation of the galactic binary signal in the Fourier domain. In contrast to traditional inpainting approaches, noise statistics are known theoretically on ungapped measurements only. This calls for the joint recovery of both the ungapped noise and the galactic binary signal. We thoroughly show that sparse inpainting yields an accurate estimation of the gravitational imprint of the galactic binaries. Additionally, we highlight that the proposed algorithm produces a statistically consistent ungapped noise estimate. We further evaluate the performances of the proposed inpainting methods to recover the gravitational wave signal on a simple example involving verification galactic binaries recently proposed in LISA data challenges. |
0709.0073 | Alejandro Cabo | Alejandro Cabo Bizet and Alejandro Cabo Montes de Oca | Static Universe model existing due to the Matter-Dark Energy coupling | 5 pages, 4 figures, a file of a different work was somehow uploaded
in the past version. We regret this happening | null | null | null | gr-qc | null | The work investigate a static, isotropic and almost homogeneous Universe
containing a real scalar field modeling the Dark-Energy (quintaessence)
interacting with pressureless matter. It is argued that the interaction between
matter and the Dark Energy, is essential for the very existence of the
considered solution. Assuming the possibility that Dark-Energy can be furnished
by the Dilaton (a scalar field reflecting the condensation of string states
with zero angular momentum) we fix the value of scalar field at the origin to
the Planck scale. It became possible to fix the ratio of the amount of Dark
Energy to matter energy, in the currently estimated value 0.7/0.3, and also the
observed magnitude of the Hubble constant. The value of the mass for the scalar
field chosen for fixing the above ratio and Hubble effect strength, results to
be of the order of 10^{-29}cm^{-1}, a small mass which seems to be compatible
with the zero mass of the Dilaton in the lowest approximations.
| [
{
"created": "Sat, 1 Sep 2007 19:37:43 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Sep 2007 12:41:13 GMT",
"version": "v2"
}
] | 2007-09-04 | [
[
"Bizet",
"Alejandro Cabo",
""
],
[
"de Oca",
"Alejandro Cabo Montes",
""
]
] | The work investigate a static, isotropic and almost homogeneous Universe containing a real scalar field modeling the Dark-Energy (quintaessence) interacting with pressureless matter. It is argued that the interaction between matter and the Dark Energy, is essential for the very existence of the considered solution. Assuming the possibility that Dark-Energy can be furnished by the Dilaton (a scalar field reflecting the condensation of string states with zero angular momentum) we fix the value of scalar field at the origin to the Planck scale. It became possible to fix the ratio of the amount of Dark Energy to matter energy, in the currently estimated value 0.7/0.3, and also the observed magnitude of the Hubble constant. The value of the mass for the scalar field chosen for fixing the above ratio and Hubble effect strength, results to be of the order of 10^{-29}cm^{-1}, a small mass which seems to be compatible with the zero mass of the Dilaton in the lowest approximations. |
1008.3137 | Burkhard Kleihaus | Betti Hartmann, Burkhard Kleihaus, Jutta Kunz, Meike List | Rotating Boson Stars in 5 Dimensions | 17 pages, 6 figures | Phys.Rev.D82:084022,2010 | 10.1103/PhysRevD.82.084022 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study rotating boson stars in five spacetime dimensions. The boson fields
consist of a complex doublet scalar field. Considering boson stars rotating in
two orthogonal planes with both angular momenta of equal magnitude, a special
ansatz for the boson field and the metric allows for solutions with nontrivial
dependence on the radial coordinate only. The charge of the scalar field equals
the sum of the angular momenta. The rotating boson stars are globally regular
and asymptotically flat. For our choice of a sixtic potential the rotating
boson star solutions possess a flat spacetime limit. We study the solutions in
flat and curved spacetime.
| [
{
"created": "Wed, 18 Aug 2010 17:19:48 GMT",
"version": "v1"
}
] | 2014-11-21 | [
[
"Hartmann",
"Betti",
""
],
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
],
[
"List",
"Meike",
""
]
] | We study rotating boson stars in five spacetime dimensions. The boson fields consist of a complex doublet scalar field. Considering boson stars rotating in two orthogonal planes with both angular momenta of equal magnitude, a special ansatz for the boson field and the metric allows for solutions with nontrivial dependence on the radial coordinate only. The charge of the scalar field equals the sum of the angular momenta. The rotating boson stars are globally regular and asymptotically flat. For our choice of a sixtic potential the rotating boson star solutions possess a flat spacetime limit. We study the solutions in flat and curved spacetime. |
1806.04547 | Sergei Kopeikin | Sergei M. Kopeikin (University of Missouri, USA) | Carter-like Constant of Motion in Newtonian Gravity is the Vinti
Integral | 2 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compare the Vinti integral of the classic celestial mechanics with a
conserved Carter-like integral of motion for an axially-symmetric body in the
Newtonian theory that has been recently found by Clifford Will. We demonstrate
that the integrals are identical. It sheds new light on the Newtonian limit of
the Kerr geometry.
| [
{
"created": "Mon, 11 Jun 2018 17:07:05 GMT",
"version": "v1"
}
] | 2018-06-13 | [
[
"Kopeikin",
"Sergei M.",
"",
"University of Missouri, USA"
]
] | We compare the Vinti integral of the classic celestial mechanics with a conserved Carter-like integral of motion for an axially-symmetric body in the Newtonian theory that has been recently found by Clifford Will. We demonstrate that the integrals are identical. It sheds new light on the Newtonian limit of the Kerr geometry. |
1207.4303 | Diego Rubiera-Garcia | Gonzalo J. Olmo and Diego Rubiera-Garcia | Nonsingular charged black holes \`{a} la Palatini | 10 single column pages | null | 10.1142/S0218271812500678 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We argue that the quantum nature of matter and gravity should lead to a
discretization of the allowed states of the matter confined in the interior of
black holes. To support and illustrate this idea, we consider a quadratic
extension of General Relativity formulated \`{a} la Palatini and show that
nonrotating, electrically charged black holes develop a compact core at the
Planck density which is nonsingular if the mass spectrum satisfies a certain
discreteness condition. We also find that the area of the core is proportional
to the number of charges times the Planck area.
| [
{
"created": "Wed, 18 Jul 2012 08:45:42 GMT",
"version": "v1"
}
] | 2015-06-05 | [
[
"Olmo",
"Gonzalo J.",
""
],
[
"Rubiera-Garcia",
"Diego",
""
]
] | We argue that the quantum nature of matter and gravity should lead to a discretization of the allowed states of the matter confined in the interior of black holes. To support and illustrate this idea, we consider a quadratic extension of General Relativity formulated \`{a} la Palatini and show that nonrotating, electrically charged black holes develop a compact core at the Planck density which is nonsingular if the mass spectrum satisfies a certain discreteness condition. We also find that the area of the core is proportional to the number of charges times the Planck area. |
0804.4184 | Lawrence E. Kidder | Michael Boyle, Alessandra Buonanno, Lawrence E. Kidder, Abdul H.
Mrou\'e, Yi Pan, Harald P. Pfeiffer, Mark A. Scheel | High-accuracy numerical simulation of black-hole binaries: Computation
of the gravitational-wave energy flux and comparisons with post-Newtonian
approximants | modified non-Keplerian flux improves agreement with NR; updated error
bound of NR-PN comparison; added refs | Phys.Rev.D78:104020,2008 | 10.1103/PhysRevD.78.104020 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Expressions for the gravitational wave (GW) energy flux and center-of-mass
energy of a compact binary are integral building blocks of post-Newtonian (PN)
waveforms. In this paper, we compute the GW energy flux and GW frequency
derivative from a highly accurate numerical simulation of an equal-mass,
non-spinning black hole binary. We also estimate the (derivative of the)
center-of-mass energy from the simulation by assuming energy balance. We
compare these quantities with the predictions of various PN approximants
(adiabatic Taylor and Pade models; non-adiabatic effective-one-body (EOB)
models). We find that Pade summation of the energy flux does not accelerate the
convergence of the flux series; nevertheless, the Pade flux is markedly closer
to the numerical result for the whole range of the simulation (about 30 GW
cycles). Taylor and Pade models overestimate the increase in flux and frequency
derivative close to merger, whereas EOB models reproduce more faithfully the
shape of and are closer to the numerical flux, frequency derivative and
derivative of energy. We also compare the GW phase of the numerical simulation
with Pade and EOB models. Matching numerical and untuned 3.5 PN order
waveforms, we find that the phase difference accumulated until $M \omega = 0.1$
is -0.12 radians for Pade approximants, and 0.50 (0.45) radians for an EOB
approximant with Keplerian (non-Keplerian) flux. We fit free parameters within
the EOB models to minimize the phase difference, and confirm degeneracies among
these parameters. By tuning pseudo 4PN order coefficients in the radial
potential or in the flux, or, if present, the location of the pole in the flux,
we find that the accumulated phase difference can be reduced - if desired - to
much less than the estimated numerical phase error (0.02 radians).
| [
{
"created": "Fri, 25 Apr 2008 22:21:05 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Oct 2008 15:16:51 GMT",
"version": "v2"
}
] | 2009-02-23 | [
[
"Boyle",
"Michael",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"Mroué",
"Abdul H.",
""
],
[
"Pan",
"Yi",
""
],
[
"Pfeiffer",
"Harald P.",
""
],
[
"Scheel",
"Mark A.",
""
]
] | Expressions for the gravitational wave (GW) energy flux and center-of-mass energy of a compact binary are integral building blocks of post-Newtonian (PN) waveforms. In this paper, we compute the GW energy flux and GW frequency derivative from a highly accurate numerical simulation of an equal-mass, non-spinning black hole binary. We also estimate the (derivative of the) center-of-mass energy from the simulation by assuming energy balance. We compare these quantities with the predictions of various PN approximants (adiabatic Taylor and Pade models; non-adiabatic effective-one-body (EOB) models). We find that Pade summation of the energy flux does not accelerate the convergence of the flux series; nevertheless, the Pade flux is markedly closer to the numerical result for the whole range of the simulation (about 30 GW cycles). Taylor and Pade models overestimate the increase in flux and frequency derivative close to merger, whereas EOB models reproduce more faithfully the shape of and are closer to the numerical flux, frequency derivative and derivative of energy. We also compare the GW phase of the numerical simulation with Pade and EOB models. Matching numerical and untuned 3.5 PN order waveforms, we find that the phase difference accumulated until $M \omega = 0.1$ is -0.12 radians for Pade approximants, and 0.50 (0.45) radians for an EOB approximant with Keplerian (non-Keplerian) flux. We fit free parameters within the EOB models to minimize the phase difference, and confirm degeneracies among these parameters. By tuning pseudo 4PN order coefficients in the radial potential or in the flux, or, if present, the location of the pole in the flux, we find that the accumulated phase difference can be reduced - if desired - to much less than the estimated numerical phase error (0.02 radians). |
gr-qc/0403022 | Robert T. Jantzen | Donato Bini, Christian Cherubini, Robert T. Jantzen, Giovanni Miniutti | The Simon and Simon-Mars Tensors for Stationary Einstein-Maxwell Fields | 12 pages, Latex IOP article class, no figures | Class.Quant.Grav. 21 (2004) 1987-1998 | 10.1088/0264-9381/21/8/005 | null | gr-qc | null | Modulo conventional scale factors, the Simon and Simon-Mars tensors are
defined for stationary vacuum spacetimes so that their equality follows from
the Bianchi identities of the second kind. In the nonvacuum case one can absorb
additional source terms into a redefinition of the Simon tensor so that this
equality is maintained. Among the electrovacuum class of solutions of the
Einstein-Maxwell equations, the expression for the Simon tensor in the
Kerr-Newman-Taub-NUT spacetime in terms of the Ernst potential is formally the
same as in the vacuum case (modulo a scale factor), and its vanishing
guarantees the simultaneous alignment of the principal null directions of the
Weyl tensor, the Papapetrou field associated with the timelike Killing vector
field, the electromagnetic field of the spacetime and even the Killing-Yano
tensor.
| [
{
"created": "Thu, 4 Mar 2004 15:59:12 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Bini",
"Donato",
""
],
[
"Cherubini",
"Christian",
""
],
[
"Jantzen",
"Robert T.",
""
],
[
"Miniutti",
"Giovanni",
""
]
] | Modulo conventional scale factors, the Simon and Simon-Mars tensors are defined for stationary vacuum spacetimes so that their equality follows from the Bianchi identities of the second kind. In the nonvacuum case one can absorb additional source terms into a redefinition of the Simon tensor so that this equality is maintained. Among the electrovacuum class of solutions of the Einstein-Maxwell equations, the expression for the Simon tensor in the Kerr-Newman-Taub-NUT spacetime in terms of the Ernst potential is formally the same as in the vacuum case (modulo a scale factor), and its vanishing guarantees the simultaneous alignment of the principal null directions of the Weyl tensor, the Papapetrou field associated with the timelike Killing vector field, the electromagnetic field of the spacetime and even the Killing-Yano tensor. |
1112.4882 | Torsten Asselmeyer-Maluga | T. Asselmeyer-Maluga and J. Krol | Exotic Smoothness and Quantum Gravity II: exotic R^4, singularities and
cosmology | 23 pages, 5 figures, iopart style, important changes in the global
hyperbolicity part thanks to M. Sanchez | null | null | null | gr-qc hep-th math-ph math.GT math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Since the first work on exotic smoothness in physics, it was folklore to
assume a direct influence of exotic smoothness to quantum gravity. In the
second paper, we calculate the "smoothness structure" part of the path integral
in quantum gravity for the exotic R^4 as non-compact manifold. We discuss the
influence of the "sum over geometries" to the "sum over smoothness structure".
There are two types of exotic R^4: large (no smooth embedded 3-sphere) and
small (smooth embedded 3-sphere). A large exotic R^4 can be produced by using
topologically slice but smoothly non-slice knots whereas a small exotic R^4 is
constructed by a 5-dimensional h-cobordism between compact 4-manifolds. The
results are applied to the calculation of expectation values, i.e. we discuss
the two observables, volume and Wilson loop. Then the appearance of naked
singularities is analyzed. By using Mostow rigidity, we obtain a justification
of area and volume quantization again. Finally exotic smoothness of the R^4
produces in all cases (small or large) a cosmological constant.
| [
{
"created": "Tue, 20 Dec 2011 23:27:17 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Jan 2012 13:46:35 GMT",
"version": "v2"
}
] | 2012-01-19 | [
[
"Asselmeyer-Maluga",
"T.",
""
],
[
"Krol",
"J.",
""
]
] | Since the first work on exotic smoothness in physics, it was folklore to assume a direct influence of exotic smoothness to quantum gravity. In the second paper, we calculate the "smoothness structure" part of the path integral in quantum gravity for the exotic R^4 as non-compact manifold. We discuss the influence of the "sum over geometries" to the "sum over smoothness structure". There are two types of exotic R^4: large (no smooth embedded 3-sphere) and small (smooth embedded 3-sphere). A large exotic R^4 can be produced by using topologically slice but smoothly non-slice knots whereas a small exotic R^4 is constructed by a 5-dimensional h-cobordism between compact 4-manifolds. The results are applied to the calculation of expectation values, i.e. we discuss the two observables, volume and Wilson loop. Then the appearance of naked singularities is analyzed. By using Mostow rigidity, we obtain a justification of area and volume quantization again. Finally exotic smoothness of the R^4 produces in all cases (small or large) a cosmological constant. |
2105.03485 | Stephanie Brown | Stephanie M. Brown and Collin D. Capano and Badri Krishnan | Using gravitational waves to distinguish between neutron stars and black
holes in compact binary mergers | 16 pages, 7 figures, 13 tables | ApJ 941 98 (2022) | 10.3847/1538-4357/ac98fe | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In August 2017, the first detection of a binary neutron star merger,
GW170817, made it possible to study neutron stars in compact binary systems
using gravitational waves. Despite being the loudest gravitational wave event
detected to date (in terms of signal-to-noise ratio), it was not possible to
unequivocally determine that GW170817 was caused by the merger of two neutron
stars instead of two black holes from the gravitational-wave data alone. That
distinction was primarily due to the accompanying electromagnetic counterpart.
This raises the question: under what circumstances can gravitational-wave data
alone, in the absence of an electromagnetic signal, be used to distinguish
between different types of mergers? Here, we study whether a neutron star-black
hole binary merger can be distinguished from a binary black hole merger using
gravitational-wave data alone. We build on earlier results using chiral
effective field theory to explore whether the data from LIGO and Virgo, LIGO
A+, LIGO Voyager, the Einstein Telescope, or Cosmic Explorer could lead to such
a distinction. The results suggest that the present LIGO-Virgo detector network
will most likely be unable to distinguish between these systems even with the
planned near-term upgrades. However, given an event with favorable parameters,
third-generation instruments such as Cosmic Explorer will be capable of making
this distinction. This result further strengthens the science case for
third-generation detectors.
| [
{
"created": "Fri, 7 May 2021 20:06:44 GMT",
"version": "v1"
},
{
"created": "Mon, 23 Jan 2023 18:43:44 GMT",
"version": "v2"
}
] | 2023-01-24 | [
[
"Brown",
"Stephanie M.",
""
],
[
"Capano",
"Collin D.",
""
],
[
"Krishnan",
"Badri",
""
]
] | In August 2017, the first detection of a binary neutron star merger, GW170817, made it possible to study neutron stars in compact binary systems using gravitational waves. Despite being the loudest gravitational wave event detected to date (in terms of signal-to-noise ratio), it was not possible to unequivocally determine that GW170817 was caused by the merger of two neutron stars instead of two black holes from the gravitational-wave data alone. That distinction was primarily due to the accompanying electromagnetic counterpart. This raises the question: under what circumstances can gravitational-wave data alone, in the absence of an electromagnetic signal, be used to distinguish between different types of mergers? Here, we study whether a neutron star-black hole binary merger can be distinguished from a binary black hole merger using gravitational-wave data alone. We build on earlier results using chiral effective field theory to explore whether the data from LIGO and Virgo, LIGO A+, LIGO Voyager, the Einstein Telescope, or Cosmic Explorer could lead to such a distinction. The results suggest that the present LIGO-Virgo detector network will most likely be unable to distinguish between these systems even with the planned near-term upgrades. However, given an event with favorable parameters, third-generation instruments such as Cosmic Explorer will be capable of making this distinction. This result further strengthens the science case for third-generation detectors. |
gr-qc/9407039 | Jonathan Halliwell | C.Anastopoulos and J.J.Halliwell | Generalized Uncertainty Relations and Long Time Limits for Quantum
Brownian Motion Models | 35 pages (plain Tex, revised to avoid corruption during file
transmission), Imperial College preprint 92-93/25 (1994) | Phys.Rev.D51:6870-6885,1995 | 10.1103/PhysRevD.51.6870 | null | gr-qc cond-mat | null | We study the time evolution of the reduced Wigner function for a class of
quantum Brownian motion models. We derive two generalized uncertainty
relations. The first consists of a sharp lower bound on the uncertainty
function, $U = (\Delta p)^2 (\Delta q)^2 $, after evolution for time $t$ in the
presence of an environment. The second, a stronger and simpler result, consists
of a lower bound at time $t$ on a modified uncertainty function, essentially
the area enclosed by the $1-\sigma$ contour of the Wigner function. In both
cases the minimizing initial state is a non-minimal Gaussian pure state. These
generalized uncertainty relations supply a measure of the comparative size of
quantum and thermal fluctuations. We prove two simple inequalites, relating
uncertainty to von Neumann entropy, and the von Neumann entropy to linear
entropy. We also prove some results on the long-time limit of the Wigner
function for arbitrary initial states. For the harmonic oscillator the Wigner
function for all initial states becomes a Gaussian at large times (often, but
not always, a thermal state). We derive the explicit forms of the long-time
limit for the free particle (which does not in general go to a Gaussian), and
also for more general potentials in the approximation of high temperature.
| [
{
"created": "Tue, 26 Jul 1994 14:02:51 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Jul 1994 15:22:19 GMT",
"version": "v2"
}
] | 2011-08-11 | [
[
"Anastopoulos",
"C.",
""
],
[
"Halliwell",
"J. J.",
""
]
] | We study the time evolution of the reduced Wigner function for a class of quantum Brownian motion models. We derive two generalized uncertainty relations. The first consists of a sharp lower bound on the uncertainty function, $U = (\Delta p)^2 (\Delta q)^2 $, after evolution for time $t$ in the presence of an environment. The second, a stronger and simpler result, consists of a lower bound at time $t$ on a modified uncertainty function, essentially the area enclosed by the $1-\sigma$ contour of the Wigner function. In both cases the minimizing initial state is a non-minimal Gaussian pure state. These generalized uncertainty relations supply a measure of the comparative size of quantum and thermal fluctuations. We prove two simple inequalites, relating uncertainty to von Neumann entropy, and the von Neumann entropy to linear entropy. We also prove some results on the long-time limit of the Wigner function for arbitrary initial states. For the harmonic oscillator the Wigner function for all initial states becomes a Gaussian at large times (often, but not always, a thermal state). We derive the explicit forms of the long-time limit for the free particle (which does not in general go to a Gaussian), and also for more general potentials in the approximation of high temperature. |
1406.4552 | Juan Margalef-Bentabol | Juan Margalef-Bentabol and Eduardo J.S. Villase\~nor | Topology of the Misner Space and its g-boundary | 17 pages, 13 images (new versions update bibliography and correct
some minor typos) | General Relativity and Gravitation, 46 (2014) 1755 | 10.1007/s10714-014-1755-6 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Misner space is a simplified $2$-dimensional model of the $4$-dimensional
Taub-NUT space that reproduces some of its pathological behaviours. In this
paper we provide an explicit base of the topology of the complete Misner space
$\mathbb{R}^{1,1}/boost$. Besides we prove that some parts of this space, that
behave like topological boundaries, are equivalent to the $g$-boundaries of the
Misner space.
| [
{
"created": "Tue, 17 Jun 2014 22:36:28 GMT",
"version": "v1"
},
{
"created": "Sun, 6 Jul 2014 15:06:43 GMT",
"version": "v2"
},
{
"created": "Sun, 31 Aug 2014 13:10:09 GMT",
"version": "v3"
}
] | 2017-02-13 | [
[
"Margalef-Bentabol",
"Juan",
""
],
[
"Villaseñor",
"Eduardo J. S.",
""
]
] | The Misner space is a simplified $2$-dimensional model of the $4$-dimensional Taub-NUT space that reproduces some of its pathological behaviours. In this paper we provide an explicit base of the topology of the complete Misner space $\mathbb{R}^{1,1}/boost$. Besides we prove that some parts of this space, that behave like topological boundaries, are equivalent to the $g$-boundaries of the Misner space. |
gr-qc/0101048 | Luca Lusanna | Luca Lusanna (INFN, Firenze) | The Rest-Frame Instant Form of Metric Gravity | 106 pages, revtex file | Gen.Rel.Grav.33:1579-1696,2001 | 10.1023/A:1012297028267 | FI/TH-0010 | gr-qc | null | In a special class of globally hyperbolic, topologically trivial,
asymptotically flat at spatial infinity spacetimes selected by the requirement
of absence of supertranslations (compatible with Christodoulou-Klainermann
spacetimes) it is possible to define the {\it rest-frame instant form} of ADM
canonical gravity by using Dirac's strategy of adding ten extra variables at
spatial infinity and ten extra first class constraints implying the gauge
nature of these variables. The final canonical Hamiltonian is the weak ADM
energy and a discussion of the Hamiltonian gauge transformations generated by
the eight first class ADM constraints is given. When there is matter and the
Newton constant is switched off, one recovers the description of the matter on
the Wigner hyperplanes of the rest-frame instant form of dynamics in Minkowski
spacetime.
| [
{
"created": "Fri, 12 Jan 2001 16:13:43 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Lusanna",
"Luca",
"",
"INFN, Firenze"
]
] | In a special class of globally hyperbolic, topologically trivial, asymptotically flat at spatial infinity spacetimes selected by the requirement of absence of supertranslations (compatible with Christodoulou-Klainermann spacetimes) it is possible to define the {\it rest-frame instant form} of ADM canonical gravity by using Dirac's strategy of adding ten extra variables at spatial infinity and ten extra first class constraints implying the gauge nature of these variables. The final canonical Hamiltonian is the weak ADM energy and a discussion of the Hamiltonian gauge transformations generated by the eight first class ADM constraints is given. When there is matter and the Newton constant is switched off, one recovers the description of the matter on the Wigner hyperplanes of the rest-frame instant form of dynamics in Minkowski spacetime. |
gr-qc/0001084 | Avraham E. Mayo | Avraham E. Mayo | Can one increase the luminosity of a Schwarzschild black hole? | 17 pages, REVTEX, Submitted to Physical Review D | null | null | null | gr-qc | null | We illustrate how Hawking's radiance from a Schwarzschild black hole is
modified by the electrostatic self-interaction of the emitted charged
particles. A W.K.B approximation shows that the probability for a
self-interacting charged particle to propagate from the interior to the
exterior of the horizon is increased relative to the corresponding probability
for neutral particles. We also demonstrate how the electric potential of a
charged test object in the black hole's vicinity gives rise to pair creation.
We analyze this phenomenon semiclassically by considering the existence of the
appropriate Klein region. Finally we discuss the possible energy source for the
process.
| [
{
"created": "Wed, 26 Jan 2000 08:29:28 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Mayo",
"Avraham E.",
""
]
] | We illustrate how Hawking's radiance from a Schwarzschild black hole is modified by the electrostatic self-interaction of the emitted charged particles. A W.K.B approximation shows that the probability for a self-interacting charged particle to propagate from the interior to the exterior of the horizon is increased relative to the corresponding probability for neutral particles. We also demonstrate how the electric potential of a charged test object in the black hole's vicinity gives rise to pair creation. We analyze this phenomenon semiclassically by considering the existence of the appropriate Klein region. Finally we discuss the possible energy source for the process. |
1104.4199 | G\'abor Zsolt T\'oth | Istvan Racz, Gabor Zsolt Toth | Numerical investigation of the late-time Kerr tails | 33 pages, 12 figures | Class.Quant.Grav.28:195003,2011 | 10.1088/0264-9381/28/19/195003 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The late-time behavior of a scalar field on fixed Kerr background is examined
in a numerical framework incorporating the techniques of conformal
compactification and hyperbolic initial value formulation. The applied code is
1+(1+2) as it is based on the use of the spectral method in the angular
directions while in the time-radial section fourth order finite differencing,
along with the method of lines, is applied. The evolution of various types of
stationary and non-stationary pure multipole initial states are investigated.
The asymptotic decay rates are determined not only in the domain of outer
communication but along the event horizon and at future null infinity as well.
The decay rates are found to be different for stationary and non-stationary
initial data, and they also depend on the fall off properties of the initial
data toward future null infinity. The energy and angular momentum transfers are
found to show significantly different behavior in the initial phase of the time
evolution. The quasinormal ringing phase and the tail phase are also
investigated. In the tail phase, the decay exponents for the energy and angular
momentum losses at future null infinity are found to be smaller than at the
horizon which is in accordance with the behavior of the field itself and it
means that at late times the energy and angular momentum falling into the black
hole become negligible in comparison with the energy and angular momentum
radiated toward future null infinity. The energy and angular momentum balances
are used as additional verifications of the reliability of our numerical
method.
| [
{
"created": "Thu, 21 Apr 2011 08:14:02 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Sep 2011 13:12:49 GMT",
"version": "v2"
}
] | 2015-03-19 | [
[
"Racz",
"Istvan",
""
],
[
"Toth",
"Gabor Zsolt",
""
]
] | The late-time behavior of a scalar field on fixed Kerr background is examined in a numerical framework incorporating the techniques of conformal compactification and hyperbolic initial value formulation. The applied code is 1+(1+2) as it is based on the use of the spectral method in the angular directions while in the time-radial section fourth order finite differencing, along with the method of lines, is applied. The evolution of various types of stationary and non-stationary pure multipole initial states are investigated. The asymptotic decay rates are determined not only in the domain of outer communication but along the event horizon and at future null infinity as well. The decay rates are found to be different for stationary and non-stationary initial data, and they also depend on the fall off properties of the initial data toward future null infinity. The energy and angular momentum transfers are found to show significantly different behavior in the initial phase of the time evolution. The quasinormal ringing phase and the tail phase are also investigated. In the tail phase, the decay exponents for the energy and angular momentum losses at future null infinity are found to be smaller than at the horizon which is in accordance with the behavior of the field itself and it means that at late times the energy and angular momentum falling into the black hole become negligible in comparison with the energy and angular momentum radiated toward future null infinity. The energy and angular momentum balances are used as additional verifications of the reliability of our numerical method. |
1907.01460 | Sebastian Ulbricht | Sebastian Ulbricht, Robert Alexander M\"uller, Andrey Surzhykov | Gravitational effects on geonium and free electron $\mathrm{g}_s$-factor
measurements in a Penning trap | 12 pages, 3 figures | Phys. Rev. D 100, 064029 (2019) | 10.1103/PhysRevD.100.064029 | null | gr-qc physics.atom-ph quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a theoretical analysis of an electron confined by a Penning trap,
also known as geonium, that is affected by gravity. In particular, we
investigate the gravitational influence on the electron dynamics and the
electromagnetic field of the trap. We consider the special case of a
homogeneous gravitational field, which is represented by Rindler spacetime. In
this spacetime the Hamiltonian of an electron with anomalous magnetic moment is
constructed. Based on this Hamiltonian and the exact solution to Maxwell
equations for the field of a Penning trap in Rindler spacetime, we derived the
transition energies of geonium up to the relativistic corrections of
$1/\mathrm{c}^2$. These transition energies are used to obtain an extension of
the well known $\mathrm{g}_s$-factor formula introduced by L. S. Brown and G.
Gabrielse [Rev. Mod. Phys. 58, 233 1986].
| [
{
"created": "Tue, 2 Jul 2019 15:44:27 GMT",
"version": "v1"
},
{
"created": "Mon, 23 Sep 2019 11:25:55 GMT",
"version": "v2"
}
] | 2019-09-24 | [
[
"Ulbricht",
"Sebastian",
""
],
[
"Müller",
"Robert Alexander",
""
],
[
"Surzhykov",
"Andrey",
""
]
] | We present a theoretical analysis of an electron confined by a Penning trap, also known as geonium, that is affected by gravity. In particular, we investigate the gravitational influence on the electron dynamics and the electromagnetic field of the trap. We consider the special case of a homogeneous gravitational field, which is represented by Rindler spacetime. In this spacetime the Hamiltonian of an electron with anomalous magnetic moment is constructed. Based on this Hamiltonian and the exact solution to Maxwell equations for the field of a Penning trap in Rindler spacetime, we derived the transition energies of geonium up to the relativistic corrections of $1/\mathrm{c}^2$. These transition energies are used to obtain an extension of the well known $\mathrm{g}_s$-factor formula introduced by L. S. Brown and G. Gabrielse [Rev. Mod. Phys. 58, 233 1986]. |
1510.03204 | Hongsheng Zhang | Hongsheng Zhang, Xin-Zhou Li | Ghost free massive gravity with singular reference metrics | 6pages, no figure | Phys. Rev. D 93, 124039 (2016) | 10.1103/PhysRevD.93.124039 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An auxiliary metric (reference metric) is inevitable in massive gravity
theory. In the scenario of gauge/gravity duality, a singular reference metric
corresponds to momentum dissipations, which describes the electric and heat
conductivity for normal conductors. We demonstrate in detail that the massive
gravity with singular reference metric is ghost-free.
| [
{
"created": "Mon, 12 Oct 2015 09:49:04 GMT",
"version": "v1"
}
] | 2016-06-22 | [
[
"Zhang",
"Hongsheng",
""
],
[
"Li",
"Xin-Zhou",
""
]
] | An auxiliary metric (reference metric) is inevitable in massive gravity theory. In the scenario of gauge/gravity duality, a singular reference metric corresponds to momentum dissipations, which describes the electric and heat conductivity for normal conductors. We demonstrate in detail that the massive gravity with singular reference metric is ghost-free. |
1405.2439 | Shin'ichi Nojiri | Shin'ichi Nojiri and Sergei D. Odintsov | Instabilities and Anti-Evaporation of Reissner-Nordstr\"om Black Holes
in modified $F(R)$ gravity | LaTeX 11 pages, no figure, publication data: Physics Letters B 735,
376-382 (2014) | null | 10.1016/j.physletb.2014.06.070 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the instabilities and related anti-evaporation of the extremal
Reissner-Nordstr\"om (RN) black hole in $F(R)$ gravity. It is remarkable that
the effective electric charge can be generated for some solutions of $F(R)$
gravity without electromagnetic field. The anti-evaporation effect occurs but
it emerges only in the strong coupling limit of the effective gravitational
coupling. The instabilities of RN black hole are also investigated when the
electromagnetic sector is added to the action of $F(R)$ gravity. We show the
anti-evaporation occurs in the Maxwell-$F(R)$ gravity with the arbitrary
gravitational coupling constant although it does not occur in the
Maxwell-Einstein gravity. Furthermore, general spherically-symmetric solution
of $F(R)$ gravity in the Einstein frame is obtained.
| [
{
"created": "Sat, 10 May 2014 14:43:53 GMT",
"version": "v1"
},
{
"created": "Thu, 24 Jul 2014 11:02:56 GMT",
"version": "v2"
},
{
"created": "Thu, 2 Oct 2014 08:56:09 GMT",
"version": "v3"
},
{
"created": "Sun, 5 Oct 2014 10:21:37 GMT",
"version": "v4"
}
] | 2015-06-19 | [
[
"Nojiri",
"Shin'ichi",
""
],
[
"Odintsov",
"Sergei D.",
""
]
] | We study the instabilities and related anti-evaporation of the extremal Reissner-Nordstr\"om (RN) black hole in $F(R)$ gravity. It is remarkable that the effective electric charge can be generated for some solutions of $F(R)$ gravity without electromagnetic field. The anti-evaporation effect occurs but it emerges only in the strong coupling limit of the effective gravitational coupling. The instabilities of RN black hole are also investigated when the electromagnetic sector is added to the action of $F(R)$ gravity. We show the anti-evaporation occurs in the Maxwell-$F(R)$ gravity with the arbitrary gravitational coupling constant although it does not occur in the Maxwell-Einstein gravity. Furthermore, general spherically-symmetric solution of $F(R)$ gravity in the Einstein frame is obtained. |
2109.00875 | Steffen Gielen | Bianca Dittrich, Steffen Gielen and Susanne Schander | Lorentzian quantum cosmology goes simplicial | 47 pages, 19 figures; v4: fixed a few typos, added some references to
figures | Class. Quant. Grav. 39 (2022), 035012 | 10.1088/1361-6382/ac42ad | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We employ the methods of discrete (Lorentzian) Regge calculus for analysing
Lorentzian quantum cosmology models with a special focus on discrete analogues
of the no-boundary proposal for the early universe. We use a simple 4-polytope,
a subdivided 4-polytope and shells of discrete 3-spheres as triangulations to
model a closed universe with cosmological constant, and examine the
semiclassical path integral for these different choices. We find that the
shells give good agreement with continuum results for small values of the scale
factor and in particular for finer discretisations of the boundary 3-sphere,
while the simple and subdivided 4-polytopes can only be compared with the
continuum in certain regimes, and in particular are not able to capture a
transition from Euclidean geometry with small scale factor to a large
Lorentzian one. Finally, we consider a closed universe filled with dust
particles and discretised by shells of 3-spheres. This model can approximate
the continuum case quite well. Our results embed the no-boundary proposal in a
discrete setting where it is possibly more naturally defined, and prepare for
its discussion within the realm of spin foams.
| [
{
"created": "Thu, 2 Sep 2021 12:36:19 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Sep 2021 18:59:31 GMT",
"version": "v2"
},
{
"created": "Mon, 13 Dec 2021 15:45:00 GMT",
"version": "v3"
},
{
"created": "Mon, 17 Jan 2022 12:08:31 GMT",
"version": "v4"
}
] | 2022-01-24 | [
[
"Dittrich",
"Bianca",
""
],
[
"Gielen",
"Steffen",
""
],
[
"Schander",
"Susanne",
""
]
] | We employ the methods of discrete (Lorentzian) Regge calculus for analysing Lorentzian quantum cosmology models with a special focus on discrete analogues of the no-boundary proposal for the early universe. We use a simple 4-polytope, a subdivided 4-polytope and shells of discrete 3-spheres as triangulations to model a closed universe with cosmological constant, and examine the semiclassical path integral for these different choices. We find that the shells give good agreement with continuum results for small values of the scale factor and in particular for finer discretisations of the boundary 3-sphere, while the simple and subdivided 4-polytopes can only be compared with the continuum in certain regimes, and in particular are not able to capture a transition from Euclidean geometry with small scale factor to a large Lorentzian one. Finally, we consider a closed universe filled with dust particles and discretised by shells of 3-spheres. This model can approximate the continuum case quite well. Our results embed the no-boundary proposal in a discrete setting where it is possibly more naturally defined, and prepare for its discussion within the realm of spin foams. |
1603.02398 | Huaifan Li | Xiongying Guo, Huaifan Li, Lichun Zhang, Ren Zhao | The phase transition of higher dimensional Charged black holes | 15 pages,14 figures,references adjusted | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper,we have studied phase transitions of higher dimensional charge
black hole with spherical symmetry. we calculated the local energy and local
temperature, and find that these state parameters satisfy the first law of
thermodynamics. We analyze the critical behavior of black hole thermodynamic
system by taking state parameters $(Q,\Phi)$ of black hole thermodynamic
system, in accordance with considering to the state parameters $(P,V)$ of Van
der Waals system respectively. we obtain the critical point of black hole
thermodynamic system, and find the critical point is independent of the dual
independent variables we selected. This result for asymptotically flat space is
consistent with that for AdS spacetime, and is intrinsic property of black hole
thermodynamic system.
| [
{
"created": "Tue, 8 Mar 2016 07:09:32 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Apr 2016 09:19:44 GMT",
"version": "v2"
}
] | 2016-04-26 | [
[
"Guo",
"Xiongying",
""
],
[
"Li",
"Huaifan",
""
],
[
"Zhang",
"Lichun",
""
],
[
"Zhao",
"Ren",
""
]
] | In this paper,we have studied phase transitions of higher dimensional charge black hole with spherical symmetry. we calculated the local energy and local temperature, and find that these state parameters satisfy the first law of thermodynamics. We analyze the critical behavior of black hole thermodynamic system by taking state parameters $(Q,\Phi)$ of black hole thermodynamic system, in accordance with considering to the state parameters $(P,V)$ of Van der Waals system respectively. we obtain the critical point of black hole thermodynamic system, and find the critical point is independent of the dual independent variables we selected. This result for asymptotically flat space is consistent with that for AdS spacetime, and is intrinsic property of black hole thermodynamic system. |
gr-qc/0510025 | Alexey Toporensky | A.V.Toporensky and P.V.Tretyakov | Recollapsing Bianchi I brane worlds | 9 pages, 4 figures, to appear in Gravitation and Cosmology | Grav.Cosmol. 11 (2005) 226-228 | null | null | gr-qc | null | We investigate the possibility for a flat Bianchi I brane Universe to
recollaps due to the presence of a negative "dark radiation" and an anisotropic
stress in the form of a homogeneous magnetic field, localized on the brane.
| [
{
"created": "Fri, 7 Oct 2005 15:21:45 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Toporensky",
"A. V.",
""
],
[
"Tretyakov",
"P. V.",
""
]
] | We investigate the possibility for a flat Bianchi I brane Universe to recollaps due to the presence of a negative "dark radiation" and an anisotropic stress in the form of a homogeneous magnetic field, localized on the brane. |
1001.1266 | Christian Boehmer | Christian G. Boehmer, Lukas Hollenstein, Francisco S. N. Lobo, Sanjeev
S. Seahra | Stability of the Einstein static universe in modified theories of
gravity | 3 pages, submitted to the Proceedings of the Twelfth Marcel Grossmann
Meeting on General Relativity | null | 10.1142/9789814374552_0379 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a brief overview of the stability analysis of the Einstein static
universe in various modified theories of gravity, like f(R) gravity,
Gauss-Bonnet or f(G) gravity, and Horava-Lifshitz gravity.
| [
{
"created": "Fri, 8 Jan 2010 13:11:48 GMT",
"version": "v1"
}
] | 2016-11-15 | [
[
"Boehmer",
"Christian G.",
""
],
[
"Hollenstein",
"Lukas",
""
],
[
"Lobo",
"Francisco S. N.",
""
],
[
"Seahra",
"Sanjeev S.",
""
]
] | We present a brief overview of the stability analysis of the Einstein static universe in various modified theories of gravity, like f(R) gravity, Gauss-Bonnet or f(G) gravity, and Horava-Lifshitz gravity. |
0808.1615 | Vitor Cardoso | Vitor Cardoso, Paolo Pani, Mariano Cadoni, Marco Cavaglia | Instability of hyper-compact Kerr-like objects | 15 pages, 3 figures. To be published in CQG | Class.Quant.Grav.25:195010,2008 | 10.1088/0264-9381/25/19/195010 | null | gr-qc astro-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Viable alternatives to astrophysical black holes include hyper-compact
objects without horizon, such as gravastars, boson stars, wormholes and
superspinars. The authors have recently shown that typical rapidly-spinning
gravastars and boson stars develop a strong instability. That analysis is
extended in this paper to a wide class of horizonless objects with approximate
Kerr-like geometry. A detailed investigation of wormholes and superspinars is
presented, using plausible models and mirror boundary conditions at the
surface. Like gravastars and boson stars, these objects are unstable with very
short instability timescales. This result strengthens previous conclusions that
observed hyper-compact astrophysical objects with large rotation are likely to
be black holes.
| [
{
"created": "Tue, 12 Aug 2008 08:14:08 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Cardoso",
"Vitor",
""
],
[
"Pani",
"Paolo",
""
],
[
"Cadoni",
"Mariano",
""
],
[
"Cavaglia",
"Marco",
""
]
] | Viable alternatives to astrophysical black holes include hyper-compact objects without horizon, such as gravastars, boson stars, wormholes and superspinars. The authors have recently shown that typical rapidly-spinning gravastars and boson stars develop a strong instability. That analysis is extended in this paper to a wide class of horizonless objects with approximate Kerr-like geometry. A detailed investigation of wormholes and superspinars is presented, using plausible models and mirror boundary conditions at the surface. Like gravastars and boson stars, these objects are unstable with very short instability timescales. This result strengthens previous conclusions that observed hyper-compact astrophysical objects with large rotation are likely to be black holes. |
0906.3827 | Lukasz Glinka | Lukasz Andrzej Glinka | Thermodynamical Quantum Gravity | 16 pages | in L.A. Glinka (Ed.) "Towards New Cosmology From Quantum Gravity &
Particle Physics", Applied Mathematics and Physics, vol. 2, no. 3 (2014):
66-72 | 10.12691/amp-2-3-2 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | The canonically quantized 3+1 General Relativity with the global one
dimensionality conjecture defines the model, which dimensionally reduced and
secondary quantized yields the one-dimensional quantum field theory wherein the
generic one-point correlations create a boson mass responsible for quantum
gravity. In this paper, this simple model is developed in a wider sense. We
propose to consider the thermodynamics of space quanta, constructed ab initio
from the entropic formalism, as the quantum gravity phenomenology.
| [
{
"created": "Sat, 20 Jun 2009 20:34:19 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Jun 2014 15:10:04 GMT",
"version": "v2"
}
] | 2014-06-11 | [
[
"Glinka",
"Lukasz Andrzej",
""
]
] | The canonically quantized 3+1 General Relativity with the global one dimensionality conjecture defines the model, which dimensionally reduced and secondary quantized yields the one-dimensional quantum field theory wherein the generic one-point correlations create a boson mass responsible for quantum gravity. In this paper, this simple model is developed in a wider sense. We propose to consider the thermodynamics of space quanta, constructed ab initio from the entropic formalism, as the quantum gravity phenomenology. |
2111.03734 | Eli\v{s}ka Pol\'a\v{s}kov\'a | Eli\v{s}ka Pol\'a\v{s}kov\'a, Pavel Krtou\v{s} | Higher-dimensional black holes with multiple equal rotations | null | Phys. Rev. D 105, 044041 (2022) | 10.1103/PhysRevD.105.044041 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study a limit of the Kerr-(A)dS spacetime in a general dimension where an
arbitrary number of its rotational parameters is set equal. The resulting
metric after the limit formally splits into two parts - the first part has the
form of the Kerr-NUT-(A)dS metric analogous to the metric of the entire
spacetime, but only for the directions not subject to the limit, and the second
part can be interpreted as the K\"{a}hler metrics. However, this separation is
not integrable, thus it does not lead to a product of independent manifolds. We
also reconstruct the original number of explicit and hidden symmetries
associated with Killing vectors and Killing tensors. Therefore, the resulting
spacetime represents a special subcase of the generalized Kerr-NUT-(A)dS metric
that retains the full Killing tower of symmetries. In $D=6$, we present
evidence of an enhanced symmetry structure after the limit. Namely, we find
additional Killing vectors and show that one of the Killing tensors becomes
reducible as it can be decomposed into Killing vectors.
| [
{
"created": "Fri, 5 Nov 2021 21:38:01 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Mar 2022 16:42:27 GMT",
"version": "v2"
}
] | 2022-03-02 | [
[
"Polášková",
"Eliška",
""
],
[
"Krtouš",
"Pavel",
""
]
] | We study a limit of the Kerr-(A)dS spacetime in a general dimension where an arbitrary number of its rotational parameters is set equal. The resulting metric after the limit formally splits into two parts - the first part has the form of the Kerr-NUT-(A)dS metric analogous to the metric of the entire spacetime, but only for the directions not subject to the limit, and the second part can be interpreted as the K\"{a}hler metrics. However, this separation is not integrable, thus it does not lead to a product of independent manifolds. We also reconstruct the original number of explicit and hidden symmetries associated with Killing vectors and Killing tensors. Therefore, the resulting spacetime represents a special subcase of the generalized Kerr-NUT-(A)dS metric that retains the full Killing tower of symmetries. In $D=6$, we present evidence of an enhanced symmetry structure after the limit. Namely, we find additional Killing vectors and show that one of the Killing tensors becomes reducible as it can be decomposed into Killing vectors. |
1210.4149 | Emilio Rub\'in de Celis | E. Rub\'in de Celis, O. P. Santill\'an and C. Simeone | Probing global aspects of a geometry by the self-force on a charge;
cylindical thin-shell wormholes | 16 pages, 4 figues. Minor corrections. Accepted version for
publication in Phys. Rev. D | null | 10.1103/PhysRevD.86.124009 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain the self-interaction for a point charge in the space-time of a
cylindrical thin-shell wormhole connecting two identical locally flat
geometries with a constant deficit angle. Although this wormhole geometry is
locally indistinguishable from a cosmic string background, the corresponding
self-forces are different even at the qualitative level. In fact in the cosmic
string geometry the force is always repulsive while for the wormhole background
we find that the force may point outwards or towards the wormhole throat
depending on the parameters of the configuration. These results suggest that
the study of the electromagnetic fields of charged particles is a useful tool
for testing the global properties of a given background.
| [
{
"created": "Mon, 15 Oct 2012 19:52:13 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Nov 2012 08:13:01 GMT",
"version": "v2"
}
] | 2015-06-11 | [
[
"de Celis",
"E. Rubín",
""
],
[
"Santillán",
"O. P.",
""
],
[
"Simeone",
"C.",
""
]
] | We obtain the self-interaction for a point charge in the space-time of a cylindrical thin-shell wormhole connecting two identical locally flat geometries with a constant deficit angle. Although this wormhole geometry is locally indistinguishable from a cosmic string background, the corresponding self-forces are different even at the qualitative level. In fact in the cosmic string geometry the force is always repulsive while for the wormhole background we find that the force may point outwards or towards the wormhole throat depending on the parameters of the configuration. These results suggest that the study of the electromagnetic fields of charged particles is a useful tool for testing the global properties of a given background. |
1402.6166 | Jozef Skakala | Jozef Skakala (IISER-TVM), S. Shankaranarayanan (IISER-TVM) | No minimally coupled scalar black hole hair in Lanczos-Lovelock gravity | 9 pages, v2: minor changes, the final version accepted for
publication in Class.Quant.Grav | Class.Quant.Grav. 31 (2014) 175005 | 10.1088/0264-9381/31/17/175005 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend here the result of Bekenstein [1,2] proving the non-existence of
minimally coupled scalar black hole hair in general relativity to the
Lanczos-Lovelock gravity in arbitrary dimension with non-negative coupling
constants. The only physical requirement on the multiplet of minimally coupled
scalar fields is that it fulfills the weak energy condition. We also assume,
similarly to Bekenstein, spherical symmetry and asymptotic flatness.
| [
{
"created": "Tue, 25 Feb 2014 13:55:29 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Jul 2014 15:35:16 GMT",
"version": "v2"
}
] | 2014-08-11 | [
[
"Skakala",
"Jozef",
"",
"IISER-TVM"
],
[
"Shankaranarayanan",
"S.",
"",
"IISER-TVM"
]
] | We extend here the result of Bekenstein [1,2] proving the non-existence of minimally coupled scalar black hole hair in general relativity to the Lanczos-Lovelock gravity in arbitrary dimension with non-negative coupling constants. The only physical requirement on the multiplet of minimally coupled scalar fields is that it fulfills the weak energy condition. We also assume, similarly to Bekenstein, spherical symmetry and asymptotic flatness. |
gr-qc/0606032 | Parampreet Singh | Parampreet Singh, Kevin Vandersloot, G. V. Vereshchagin | Non-Singular Bouncing Universes in Loop Quantum Cosmology | Minor changes and one figure added to improve presentation.
References added. To appear in Physical Review D | Phys.Rev. D74 (2006) 043510 | 10.1103/PhysRevD.74.043510 | IGPG-06/6-1 | gr-qc astro-ph hep-th | null | Non-perturbative quantum geometric effects in Loop Quantum Cosmology predict
a $\rho^2$ modification to the Friedmann equation at high energies. The
quadratic term is negative definite and can lead to generic bounces when the
matter energy density becomes equal to a critical value of the order of the
Planck density. The non-singular bounce is achieved for arbitrary matter
without violation of positive energy conditions. By performing a qualitative
analysis we explore the nature of the bounce for inflationary and Cyclic model
potentials. For the former we show that inflationary trajectories are
attractors of the dynamics after the bounce implying that inflation can be
harmoniously embedded in LQC. For the latter difficulties associated with
singularities in cyclic models can be overcome. We show that non-singular
cyclic models can be constructed with a small variation in the original Cyclic
model potential by making it slightly positive in the regime where scalar field
is negative.
| [
{
"created": "Wed, 7 Jun 2006 15:41:50 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Jul 2006 19:50:03 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Singh",
"Parampreet",
""
],
[
"Vandersloot",
"Kevin",
""
],
[
"Vereshchagin",
"G. V.",
""
]
] | Non-perturbative quantum geometric effects in Loop Quantum Cosmology predict a $\rho^2$ modification to the Friedmann equation at high energies. The quadratic term is negative definite and can lead to generic bounces when the matter energy density becomes equal to a critical value of the order of the Planck density. The non-singular bounce is achieved for arbitrary matter without violation of positive energy conditions. By performing a qualitative analysis we explore the nature of the bounce for inflationary and Cyclic model potentials. For the former we show that inflationary trajectories are attractors of the dynamics after the bounce implying that inflation can be harmoniously embedded in LQC. For the latter difficulties associated with singularities in cyclic models can be overcome. We show that non-singular cyclic models can be constructed with a small variation in the original Cyclic model potential by making it slightly positive in the regime where scalar field is negative. |
1802.09024 | Vasilis Oikonomou | Jaume de Haro, S.D. Odintsov, V.K. Oikonomou | Viable Inflationary Evolution from Loop Quantum Cosmology Scalar-Tensor
Theory | PRD Accepted | Phys. Rev. D 97, 084052 (2018) | 10.1103/PhysRevD.97.084052 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we construct a bottom-up reconstruction technique for Loop
Quantum Cosmology scalar-tensor theories, from the observational indices.
Particularly, the reconstruction technique is based on fixing the functional
form of the scalar-to-tensor ratio as a function of the $e$-foldings number.
The aim of the technique is to realize viable inflationary scenarios, and the
only assumption that must hold true in order for the reconstruction technique
to work is that the dynamical evolution of the scalar field obeys the slow-roll
conditions. We shall use two functional forms for the scalar-to-tensor ratio,
one of which corresponds to a popular inflationary class of models, the
$\alpha$-attractors. For the latter, we shall calculate the leading order
behavior of the spectral index and we shall demonstrate that the resulting
inflationary theory is viable and compatible with the latest Planck and
BICEP2/Keck-Array data. In addition, we shall find the classical limit of the
theory, and as we demonstrate, the Loop Quantum Cosmology corrected theory and
the classical theory are identical at leading order in the perturbative
expansion quantified by the parameter $\rho_c$, which is the critical density
of the quantum theory. Finally, by using the formalism of slow-roll
scalar-tensor Loop Quantum Cosmology, we shall investigate how several
inflationary potentials can be realized by the quantum theory, and we shall
calculate directly the slow-roll indices and the corresponding observational
indices. In addition, the $f(R)$ gravity frame picture is presented.
| [
{
"created": "Sun, 25 Feb 2018 15:38:39 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Apr 2018 16:27:13 GMT",
"version": "v2"
}
] | 2018-05-02 | [
[
"de Haro",
"Jaume",
""
],
[
"Odintsov",
"S. D.",
""
],
[
"Oikonomou",
"V. K.",
""
]
] | In this work we construct a bottom-up reconstruction technique for Loop Quantum Cosmology scalar-tensor theories, from the observational indices. Particularly, the reconstruction technique is based on fixing the functional form of the scalar-to-tensor ratio as a function of the $e$-foldings number. The aim of the technique is to realize viable inflationary scenarios, and the only assumption that must hold true in order for the reconstruction technique to work is that the dynamical evolution of the scalar field obeys the slow-roll conditions. We shall use two functional forms for the scalar-to-tensor ratio, one of which corresponds to a popular inflationary class of models, the $\alpha$-attractors. For the latter, we shall calculate the leading order behavior of the spectral index and we shall demonstrate that the resulting inflationary theory is viable and compatible with the latest Planck and BICEP2/Keck-Array data. In addition, we shall find the classical limit of the theory, and as we demonstrate, the Loop Quantum Cosmology corrected theory and the classical theory are identical at leading order in the perturbative expansion quantified by the parameter $\rho_c$, which is the critical density of the quantum theory. Finally, by using the formalism of slow-roll scalar-tensor Loop Quantum Cosmology, we shall investigate how several inflationary potentials can be realized by the quantum theory, and we shall calculate directly the slow-roll indices and the corresponding observational indices. In addition, the $f(R)$ gravity frame picture is presented. |
1906.01826 | Alexander Breev | A. I. Breev and A. V. Shapovalov | Vacuum quantum effects on Lie groups with bi-invariant metrics | 28 pages, version accepted for publication in Int. J. Geom. Methods
Mod. Phys | Int. J. Geom. Methods Mod. Phys (2019) | 10.1142/S0219887819501226 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the effects of vacuum polarization and particle creation of a
scalar field on Lie groups with a non-stationary bi-invariant metric of the
Robertson-Walker type. The vacuum expectation values of the energy momentum
tensor for a scalar field determined by the group representation are found
using the noncommutative integration method for the field equations instead of
separation of variables. The results obtained are illustrated by the example of
the three-dimensional rotation group.
| [
{
"created": "Wed, 5 Jun 2019 05:09:39 GMT",
"version": "v1"
}
] | 2019-07-01 | [
[
"Breev",
"A. I.",
""
],
[
"Shapovalov",
"A. V.",
""
]
] | We consider the effects of vacuum polarization and particle creation of a scalar field on Lie groups with a non-stationary bi-invariant metric of the Robertson-Walker type. The vacuum expectation values of the energy momentum tensor for a scalar field determined by the group representation are found using the noncommutative integration method for the field equations instead of separation of variables. The results obtained are illustrated by the example of the three-dimensional rotation group. |
2308.07355 | Paola Carolina Moreira Delgado | Paola C. M. Delgado | Introdu\c{c}\~ao \`a Cosmologia Qu\^antica | 11 pages, in Portuguese, 3 figures, version accepted for publication
in Cadernos de Astronomia | null | 10.47456/Cad.Astro.v4n2.41563 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This review presents an introduction to Quantum Cosmology, including the
mathematical methods essential to the canonical approach, some of the existing
conceptual problems and the connection of the models to possible observables.
| [
{
"created": "Mon, 14 Aug 2023 11:48:23 GMT",
"version": "v1"
}
] | 2023-09-19 | [
[
"Delgado",
"Paola C. M.",
""
]
] | This review presents an introduction to Quantum Cosmology, including the mathematical methods essential to the canonical approach, some of the existing conceptual problems and the connection of the models to possible observables. |
1206.1271 | Jose Luis Jaramillo | Jos\'e Luis Jaramillo | A note on degeneracy, marginal stability and extremality of black hole
horizons | 6 pages, no figures, updated to match published version | Class.Quant.Grav. 29 (2012) 177001 | 10.1088/0264-9381/29/17/177001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Given a stationary axisymmetric black hole horizon admitting a section
characterised as a strictly future stable marginally outer trapped surface, we
extend the equivalence between the notions of horizon degeneracy and marginal
stability to the fulfillment, under the dominant energy condition, of the
A=8\pi |J| geometric relation between the area $A$ and the angular momentum J
of a horizon section.
| [
{
"created": "Wed, 6 Jun 2012 16:42:44 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Aug 2012 09:14:45 GMT",
"version": "v2"
}
] | 2012-08-28 | [
[
"Jaramillo",
"José Luis",
""
]
] | Given a stationary axisymmetric black hole horizon admitting a section characterised as a strictly future stable marginally outer trapped surface, we extend the equivalence between the notions of horizon degeneracy and marginal stability to the fulfillment, under the dominant energy condition, of the A=8\pi |J| geometric relation between the area $A$ and the angular momentum J of a horizon section. |
gr-qc/0005036 | Farhad Darabi | F. Darabi, W. N. Sajko, P. S. Wesson | Quantum cosmology of 5D non-compactified Kaluza-Klein theory | 14 pages, LaTeX | Class.Quant.Grav. 17 (2000) 4357-4364 | 10.1088/0264-9381/17/21/301 | null | gr-qc | null | We study the quantum cosmology of a five dimensional non-compactified
Kaluza-Klein theory where the 4D metric depends on the fifth coordinate,
$x^4\equiv l$. This model is effectively equivalent to a 4D non-minimally
coupled dilaton field in addition to matter generated on hypersurfaces
l=constant by the extra coordinate dependence in the four-dimensional metric.
We show that the Vilenkin wave function of the universe is more convenient for
this model as it predicts a new-born 4D universe on the $l\simeq0$ constant
hypersurface.
| [
{
"created": "Wed, 10 May 2000 23:28:20 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Darabi",
"F.",
""
],
[
"Sajko",
"W. N.",
""
],
[
"Wesson",
"P. S.",
""
]
] | We study the quantum cosmology of a five dimensional non-compactified Kaluza-Klein theory where the 4D metric depends on the fifth coordinate, $x^4\equiv l$. This model is effectively equivalent to a 4D non-minimally coupled dilaton field in addition to matter generated on hypersurfaces l=constant by the extra coordinate dependence in the four-dimensional metric. We show that the Vilenkin wave function of the universe is more convenient for this model as it predicts a new-born 4D universe on the $l\simeq0$ constant hypersurface. |
1206.0331 | B. S. Sathyaprakash | B. Sathyaprakash, M. Abernathy, F. Acernese, P. Ajith, B. Allen, P.
Amaro-Seoane, N. Andersson, S. Aoudia, K. Arun, P. Astone, B. Krishnan, L.
Barack, F. Barone, B. Barr, M. Barsuglia, M. Bassan, R. Bassiri, M. Beker, N.
Beveridge, M. Bizouard, C. Bond, S. Bose, L. Bosi, S. Braccini, C.
Bradaschia, M. Britzger, F. Brueckner, T. Bulik, H. J. Bulten, O. Burmeister,
E. Calloni, P. Campsie, L. Carbone, G. Cella, E. Chalkley, E.
Chassande-Mottin, S. Chelkowski, A. Chincarini, A. Di. Cintio, J. Clark, E.
Coccia, C. N. Colacino, J. Colas, A. Colla, A. Corsi, A. Cumming, L.
Cunningham, E. Cuoco, S. Danilishin, K. Danzmann, E. Daw, R. De. Salvo, W.
Del. Pozzo, T. Dent, R. De. Rosa, L. Di. Fiore, M. Di. Paolo. Emilio, A. Di.
Virgilio, A. Dietz, M. Doets, J. Dueck, M. Edwards, V. Fafone, S. Fairhurst,
P. Falferi, M. Favata, V. Ferrari, F. Ferrini, F. Fidecaro, R. Flaminio, J.
Franc, F. Frasconi, A. Freise, D. Friedrich, P. Fulda, J. Gair, M.
Galimberti, G. Gemme, E. Genin, A. Gennai, A. Giazotto, K. Glampedakis, S.
Gossan, R. Gouaty, C. Graef, W. Graham, M. Granata, H. Grote, G. Guidi, J.
Hallam, G. Hammond, M. Hannam, J. Harms, K. Haughian, I. Hawke, D. Heinert,
M. Hendry, I. Heng, E. Hennes, S. Hild, J. Hough, D. Huet, S. Husa, S.
Huttner, B. Iyer, D. I. Jones, G. Jones, I. Kamaretsos, C. Kant Mishra, F.
Kawazoe, F. Khalili, B. Kley, K. Kokeyama, K. Kokkotas, S. Kroker, R. Kumar,
K. Kuroda, B. Lagrange, N. Lastzka, T. G. F. Li, M. Lorenzini, G. Losurdo, H.
L\"uck, E. Majorana, V. Malvezzi, I. Mandel, V. Mandic, S. Marka, F. Marin,
F. Marion, J. Marque, I. Martin, D. Mc. Leod, D. Mckechan, M. Mehmet, C.
Michel, Y. Minenkov, N. Morgado, A. Morgia, S. Mosca, L. Moscatelli, B.
Mours, H. M\"uller-Ebhardt, P. Murray, L. Naticchioni, R. Nawrodt, J. Nelson,
R. O'. Shaughnessy, C. D. Ott, C. Palomba, A. Paoli, G. Parguez, A.
Pasqualetti, R. Passaquieti, D. Passuello, M. Perciballi, F. Piergiovanni, L.
Pinard, M. Pitkin, W. Plastino, M. Plissi, R. Poggiani, P. Popolizio, E.
Porter, M. Prato, G. Prodi, M. Punturo, P. Puppo, D. Rabeling, I. Racz, P.
Rapagnani, V. Re, J. Read, T. Regimbau, H. Rehbein, S. Reid, F. Ricci, F.
Richard, C. Robinson, A. Rocchi, R. Romano, S. Rowan, A. R\"udiger, A.
Samblowski, L. Santamar\'ia, B. Sassolas, R. Schilling, P. Schmidt, R.
Schnabel, B. Schutz, C. Schwarz, J. Scott, P. Seidel, A. M. Sintes, K.
Somiya, C. F. Sopuerta, B. Sorazu, F. Speirits, L. Storchi, K. Strain, S.
Strigin, P. Sutton, S. Tarabrin, B. Taylor, A. Th\"urin, K. Tokmakov, M.
Tonelli, H. Tournefier, R. Vaccarone, H. Vahlbruch, J. F. J. van. den. Brand,
C. Van. Den. Broeck, S. van. der. Putten, M. van. Veggel, A. Vecchio, J.
Veitch, F. Vetrano, A. Vicere, S. Vyatchanin, P. We{\ss}els, B. Willke, W.
Winkler, G. Woan, A. Woodcraft, K. Yamamoto | Scientific Objectives of Einstein Telescope | 18 pages, 4 figures, Plenary talk given at Amaldi Meeting, July 2011 | Class. Quantum Grav. 29, 124013, 2012 | 10.1088/0264-9381/29/12/124013 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The advanced interferometer network will herald a new era in observational
astronomy. There is a very strong science case to go beyond the advanced
detector network and build detectors that operate in a frequency range from 1
Hz-10 kHz, with sensitivity a factor ten better in amplitude. Such detectors
will be able to probe a range of topics in nuclear physics, astronomy,
cosmology and fundamental physics, providing insights into many unsolved
problems in these areas.
| [
{
"created": "Sat, 2 Jun 2012 00:04:12 GMT",
"version": "v1"
}
] | 2012-06-05 | [
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"Bose",
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[
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[
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"Bulten",
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[
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[
"Colacino",
"C. N.",
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[
"Colas",
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[
"Colla",
"A.",
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"Corsi",
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"Fulda",
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[
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[
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[
"Glampedakis",
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[
"Gossan",
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"R.",
""
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[
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"C.",
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[
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""
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[
"Granata",
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[
"Hallam",
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"M.",
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"I.",
""
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"Hendry",
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""
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[
"Heng",
"I.",
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[
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""
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[
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[
"Iyer",
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"D. I.",
""
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[
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""
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[
"Kamaretsos",
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"C. Kant",
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"F.",
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[
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"K.",
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[
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""
],
[
"Kumar",
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""
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[
"Kuroda",
"K.",
""
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[
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"B.",
""
],
[
"Lastzka",
"N.",
""
],
[
"Li",
"T. G. F.",
""
],
[
"Lorenzini",
"M.",
""
],
[
"Losurdo",
"G.",
""
],
[
"Lück",
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""
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[
"Majorana",
"E.",
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[
"Malvezzi",
"V.",
""
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[
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"I.",
""
],
[
"Mandic",
"V.",
""
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[
"Marka",
"S.",
""
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[
"Marin",
"F.",
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[
"Marion",
"F.",
""
],
[
"Marque",
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""
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[
"Martin",
"I.",
""
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[
"Leod",
"D. Mc.",
""
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[
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"D.",
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[
"Mehmet",
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""
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[
"Michel",
"C.",
""
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[
"Minenkov",
"Y.",
""
],
[
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"N.",
""
],
[
"Morgia",
"A.",
""
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[
"Mosca",
"S.",
""
],
[
"Moscatelli",
"L.",
""
],
[
"Mours",
"B.",
""
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[
"Müller-Ebhardt",
"H.",
""
],
[
"Murray",
"P.",
""
],
[
"Naticchioni",
"L.",
""
],
[
"Nawrodt",
"R.",
""
],
[
"Nelson",
"J.",
""
],
[
"Shaughnessy",
"R. O'.",
""
],
[
"Ott",
"C. D.",
""
],
[
"Palomba",
"C.",
""
],
[
"Paoli",
"A.",
""
],
[
"Parguez",
"G.",
""
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[
"Pasqualetti",
"A.",
""
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[
"Passaquieti",
"R.",
""
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[
"Passuello",
"D.",
""
],
[
"Perciballi",
"M.",
""
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[
"Piergiovanni",
"F.",
""
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[
"Pinard",
"L.",
""
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[
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"M.",
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[
"Plastino",
"W.",
""
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[
"Plissi",
"M.",
""
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[
"Poggiani",
"R.",
""
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[
"Popolizio",
"P.",
""
],
[
"Porter",
"E.",
""
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[
"Prato",
"M.",
""
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"G.",
""
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"Punturo",
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""
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[
"Puppo",
"P.",
""
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[
"Rabeling",
"D.",
""
],
[
"Racz",
"I.",
""
],
[
"Rapagnani",
"P.",
""
],
[
"Re",
"V.",
""
],
[
"Read",
"J.",
""
],
[
"Regimbau",
"T.",
""
],
[
"Rehbein",
"H.",
""
],
[
"Reid",
"S.",
""
],
[
"Ricci",
"F.",
""
],
[
"Richard",
"F.",
""
],
[
"Robinson",
"C.",
""
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[
"Rocchi",
"A.",
""
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[
"Romano",
"R.",
""
],
[
"Rowan",
"S.",
""
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[
"Rüdiger",
"A.",
""
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[
"Samblowski",
"A.",
""
],
[
"Santamaría",
"L.",
""
],
[
"Sassolas",
"B.",
""
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[
"Schilling",
"R.",
""
],
[
"Schmidt",
"P.",
""
],
[
"Schnabel",
"R.",
""
],
[
"Schutz",
"B.",
""
],
[
"Schwarz",
"C.",
""
],
[
"Scott",
"J.",
""
],
[
"Seidel",
"P.",
""
],
[
"Sintes",
"A. M.",
""
],
[
"Somiya",
"K.",
""
],
[
"Sopuerta",
"C. F.",
""
],
[
"Sorazu",
"B.",
""
],
[
"Speirits",
"F.",
""
],
[
"Storchi",
"L.",
""
],
[
"Strain",
"K.",
""
],
[
"Strigin",
"S.",
""
],
[
"Sutton",
"P.",
""
],
[
"Tarabrin",
"S.",
""
],
[
"Taylor",
"B.",
""
],
[
"Thürin",
"A.",
""
],
[
"Tokmakov",
"K.",
""
],
[
"Tonelli",
"M.",
""
],
[
"Tournefier",
"H.",
""
],
[
"Vaccarone",
"R.",
""
],
[
"Vahlbruch",
"H.",
""
],
[
"Brand",
"J. F. J. van. den.",
""
],
[
"Broeck",
"C. Van. Den.",
""
],
[
"Putten",
"S. van. der.",
""
],
[
"Veggel",
"M. van.",
""
],
[
"Vecchio",
"A.",
""
],
[
"Veitch",
"J.",
""
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[
"Vetrano",
"F.",
""
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[
"Vicere",
"A.",
""
],
[
"Vyatchanin",
"S.",
""
],
[
"Weßels",
"P.",
""
],
[
"Willke",
"B.",
""
],
[
"Winkler",
"W.",
""
],
[
"Woan",
"G.",
""
],
[
"Woodcraft",
"A.",
""
],
[
"Yamamoto",
"K.",
""
]
] | The advanced interferometer network will herald a new era in observational astronomy. There is a very strong science case to go beyond the advanced detector network and build detectors that operate in a frequency range from 1 Hz-10 kHz, with sensitivity a factor ten better in amplitude. Such detectors will be able to probe a range of topics in nuclear physics, astronomy, cosmology and fundamental physics, providing insights into many unsolved problems in these areas. |
gr-qc/9904072 | Mauricio Bellini | Mauricio Bellini | Towards a theory of Warm Inflation of the Universe | 14 pages, no figures, to appear in Classical and Quantum Gravity | Class.Quant.Grav. 16 (1999) 2393-2402 | 10.1088/0264-9381/16/7/316 | null | gr-qc | null | The warm inflation scenario is an alternative mechanism which can explain the
isotropic and homogeneous Universe which we are living in. In this work I
extend a previously introduced formalism, without the restriction of slow -
roll regime. Quantum to classical transition of the fluctuations is studied by
means of the "transition function" here introduced. I found that the
fluctuations of radiation energy density decrease with time and the thermal
equilibrium at the end of inflation holds.
| [
{
"created": "Tue, 27 Apr 1999 19:02:17 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Bellini",
"Mauricio",
""
]
] | The warm inflation scenario is an alternative mechanism which can explain the isotropic and homogeneous Universe which we are living in. In this work I extend a previously introduced formalism, without the restriction of slow - roll regime. Quantum to classical transition of the fluctuations is studied by means of the "transition function" here introduced. I found that the fluctuations of radiation energy density decrease with time and the thermal equilibrium at the end of inflation holds. |
1310.4143 | Mehdi Saravani | Mehdi Saravani, Niayesh Afshordi and Robert B. Mann | Dynamical Emergence of Universal Horizons during the formation of Black
Holes | 20 pages | Phys. Rev. D 89, 084029 (2014) | 10.1103/PhysRevD.89.084029 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivations for the existence of a fundamental preferred frame range from
pure phenomenology to attempts to solve the non-renormalizability of quantum
gravity, the problem of time (and scale), and the cosmological constant
problem(s). In many explicit constructions, such as Einstein-Aether or
Gravitational Aether theories, K-essence, Cuscuton theory, Shape Dynamics, or
(non-projectable) Horava-Lifshitz gravity, the low energy theory contains a
fluid (which defines a preferred frame) with superluminal or incompressible
excitations. We study here the formation of black holes in the presence of such
a fluid. In particular, we focus on the incompressible limit of the fluid (or
Constant Mean Curvature foliation) in the space-time of a spherically
collapsing shell within an asymptotically cosmological space-time. In this
case, ignoring the fluid back reaction, we can analytically show that an
observer inside 3/4 of the Schwarzschild radius cannot send a signal outside,
after a stage in collapse, even using signals that propagate infinitely fast in
the preferred frame. This confirms the dynamical emergence of universal
horizons that have been previously found in static solutions. We argue that
this universal horizon should be considered as the future boundary of the
classical space-time.
| [
{
"created": "Tue, 15 Oct 2013 18:44:46 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Jul 2014 18:33:06 GMT",
"version": "v2"
}
] | 2014-07-10 | [
[
"Saravani",
"Mehdi",
""
],
[
"Afshordi",
"Niayesh",
""
],
[
"Mann",
"Robert B.",
""
]
] | Motivations for the existence of a fundamental preferred frame range from pure phenomenology to attempts to solve the non-renormalizability of quantum gravity, the problem of time (and scale), and the cosmological constant problem(s). In many explicit constructions, such as Einstein-Aether or Gravitational Aether theories, K-essence, Cuscuton theory, Shape Dynamics, or (non-projectable) Horava-Lifshitz gravity, the low energy theory contains a fluid (which defines a preferred frame) with superluminal or incompressible excitations. We study here the formation of black holes in the presence of such a fluid. In particular, we focus on the incompressible limit of the fluid (or Constant Mean Curvature foliation) in the space-time of a spherically collapsing shell within an asymptotically cosmological space-time. In this case, ignoring the fluid back reaction, we can analytically show that an observer inside 3/4 of the Schwarzschild radius cannot send a signal outside, after a stage in collapse, even using signals that propagate infinitely fast in the preferred frame. This confirms the dynamical emergence of universal horizons that have been previously found in static solutions. We argue that this universal horizon should be considered as the future boundary of the classical space-time. |
2403.15984 | Sven Hirsch | Sven Hirsch and Yiyue Zhang | Initial data sets with vanishing mass are contained in pp-wave
spacetimes | null | null | null | null | gr-qc math.AP math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In 1981, Schoen-Yau and Witten showed that in General Relativity both the
total energy $E$ and the total mass $m$ of an initial data set modelling an
isolated gravitational system are non-negative. Moreover, if $E=0$, the initial
data set must be contained in Minkowski space. In this paper, we show that if
$m=0$, i.e. if $E$ equals the total momentum $|P|$, the initial data set must
be contained in a pp-wave spacetime. Our proof combines spinorial methods with
spacetime harmonic functions and works in all dimensions. Additionally, we find
the decay rate threshold where the embedding has to be within Minkowski space
and construct non-vacuum initial data sets with $m=0$ in the borderline case.
As a consequence, this completely settles the rigidity of the spacetime
positive mass theorem for spin manifolds.
| [
{
"created": "Sun, 24 Mar 2024 02:28:21 GMT",
"version": "v1"
}
] | 2024-03-26 | [
[
"Hirsch",
"Sven",
""
],
[
"Zhang",
"Yiyue",
""
]
] | In 1981, Schoen-Yau and Witten showed that in General Relativity both the total energy $E$ and the total mass $m$ of an initial data set modelling an isolated gravitational system are non-negative. Moreover, if $E=0$, the initial data set must be contained in Minkowski space. In this paper, we show that if $m=0$, i.e. if $E$ equals the total momentum $|P|$, the initial data set must be contained in a pp-wave spacetime. Our proof combines spinorial methods with spacetime harmonic functions and works in all dimensions. Additionally, we find the decay rate threshold where the embedding has to be within Minkowski space and construct non-vacuum initial data sets with $m=0$ in the borderline case. As a consequence, this completely settles the rigidity of the spacetime positive mass theorem for spin manifolds. |
2405.09435 | Miguel Pe\~nafiel | M. L. Pe\~nafiel and S. E. Perez Bergliaffa | On the radiation field of a linearly accelerated charged particle in
Born-Infeld theory | 41 pages, 9 figures, Accepted for publication in Annals of Physics | null | 10.1016/j.aop.2024.169691 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The electric potential and the electromagnetic field for a linearly
accelerated Born-Infeld charged particle are obtained in an inertial frame by a
method that can, in principle, be applied to any electromagnetic theory. The
method is based on (i) the fact that the metric near the horizon of a
Schwarzschild black hole is equivalent to that of Rindler spacetime, and (ii) a
theorem that guarantees that the electrostatic potential for a given nonlinear
theory in a static, spherically symmetric spacetime is entirely specified by
the Maxwellian electrostatic potential in the same background. Using analytical
and numerical methods, the features of the radiation field and the
radiation-reaction for such an accelerated particle are discussed in detail.
| [
{
"created": "Wed, 15 May 2024 15:26:47 GMT",
"version": "v1"
}
] | 2024-07-08 | [
[
"Peñafiel",
"M. L.",
""
],
[
"Bergliaffa",
"S. E. Perez",
""
]
] | The electric potential and the electromagnetic field for a linearly accelerated Born-Infeld charged particle are obtained in an inertial frame by a method that can, in principle, be applied to any electromagnetic theory. The method is based on (i) the fact that the metric near the horizon of a Schwarzschild black hole is equivalent to that of Rindler spacetime, and (ii) a theorem that guarantees that the electrostatic potential for a given nonlinear theory in a static, spherically symmetric spacetime is entirely specified by the Maxwellian electrostatic potential in the same background. Using analytical and numerical methods, the features of the radiation field and the radiation-reaction for such an accelerated particle are discussed in detail. |
1012.4730 | Robert Monjo Dr | Robert Monjo, \'Alvaro Rodr\'iguez Abella, Rutwig Campoamor-Stursberg | From coloured gravity to electromagnetism | 42 pages, no figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gauge formalism in \textit{telepalallel gravity} provides an interesting
viewpoint to describe interactions according to an anholonomic observer's
tetrad basis. Without going into assessing the complete viability of
quantization in an early stage, this paper explores classical gravity within
the framework of a classical-to-quantum bridge between the SU$(1, 3)$
Yang--Mills gauge formalism and the gauge-like treatment of teleparallel
gravity. Specifically, the perturbed spacetime algebra with Weitzenb\"ock
connection can be assimilated to a local complexification based on the
SU$(1,3)$ Yang--Mills theory, what we call hypercolor or, simply, color. The
formulation of the hypercolor dynamics is build by a translational gauge, as in
the teleparallel gravities. In particular, this work analyses small
perturbations of a metric decomposition related to the Wilson line and the
Kaluza--Klein metric, but obtaining electrodynamics in four dimensions. The
spacetime coordinates are now matrices that represent elements of the
$\mathfrak{su}(1,3)$ algebra. To make compatible the formulation of a colored
gravity with the Lorentz force and the Maxwell equations, it is enough to
define every energy potential origin as 0 in the event horizon instead of the
classic zero potential at infinity. Under the colored gravity framework,
standard electromagnetism can be obtained as a particular abelian case.
| [
{
"created": "Tue, 21 Dec 2010 16:55:52 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Jan 2011 19:57:30 GMT",
"version": "v2"
},
{
"created": "Mon, 2 Dec 2013 22:04:05 GMT",
"version": "v3"
},
{
"created": "Wed, 26 Jul 2023 22:32:15 GMT",
"version": "v4"
},
{
"created": "Sun, 9 Jun 2024 21:42:06 GMT",
"version": "v5"
},
{
"created": "Thu, 15 Aug 2024 10:57:15 GMT",
"version": "v6"
}
] | 2024-08-16 | [
[
"Monjo",
"Robert",
""
],
[
"Abella",
"Álvaro Rodríguez",
""
],
[
"Campoamor-Stursberg",
"Rutwig",
""
]
] | The gauge formalism in \textit{telepalallel gravity} provides an interesting viewpoint to describe interactions according to an anholonomic observer's tetrad basis. Without going into assessing the complete viability of quantization in an early stage, this paper explores classical gravity within the framework of a classical-to-quantum bridge between the SU$(1, 3)$ Yang--Mills gauge formalism and the gauge-like treatment of teleparallel gravity. Specifically, the perturbed spacetime algebra with Weitzenb\"ock connection can be assimilated to a local complexification based on the SU$(1,3)$ Yang--Mills theory, what we call hypercolor or, simply, color. The formulation of the hypercolor dynamics is build by a translational gauge, as in the teleparallel gravities. In particular, this work analyses small perturbations of a metric decomposition related to the Wilson line and the Kaluza--Klein metric, but obtaining electrodynamics in four dimensions. The spacetime coordinates are now matrices that represent elements of the $\mathfrak{su}(1,3)$ algebra. To make compatible the formulation of a colored gravity with the Lorentz force and the Maxwell equations, it is enough to define every energy potential origin as 0 in the event horizon instead of the classic zero potential at infinity. Under the colored gravity framework, standard electromagnetism can be obtained as a particular abelian case. |
1211.0690 | Gonzalo Olmo | Gonzalo J. Olmo, Helios Sanchis-Alepuz, Swapnil Tripathi | Static Spherically Symmetric Solutions in Extended Palatini Gravity | 3 pages, ws-procs975x65.cls, corrects some typos present in the
published version of the Proceedings of 12th Marcel Grossmann Meeting, Paris
(France) | null | 10.1142/9789814374552_0402 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider static spherically symmetric stellar configurations in Palatini
theories of gravity in which the Lagrangian is an unspecified function of the
form f(R,R_{\mu\nu}R^{\mu\nu}). We obtain the Tolman-Oppenheimer-Volkov
equations corresponding to this class of theories and show that they recover
those of f(R) theories and General Relativity in the appropriate limits. We
compute exterior vacuum solutions and comment on the possible expected
modifications, as compared to GR, of the interior solutions.
| [
{
"created": "Sun, 4 Nov 2012 15:07:50 GMT",
"version": "v1"
}
] | 2012-11-06 | [
[
"Olmo",
"Gonzalo J.",
""
],
[
"Sanchis-Alepuz",
"Helios",
""
],
[
"Tripathi",
"Swapnil",
""
]
] | We consider static spherically symmetric stellar configurations in Palatini theories of gravity in which the Lagrangian is an unspecified function of the form f(R,R_{\mu\nu}R^{\mu\nu}). We obtain the Tolman-Oppenheimer-Volkov equations corresponding to this class of theories and show that they recover those of f(R) theories and General Relativity in the appropriate limits. We compute exterior vacuum solutions and comment on the possible expected modifications, as compared to GR, of the interior solutions. |
gr-qc/9912062 | Alberto Balfagon Costa | X. Jaen (1) and A. Balfagon (2) ((1)Universitat Politecnica de
Catalunya, Laboratori de Fisica Matematica,Societat Catalana de
Fisica(I.E.C.), (2)Institut Quimic de Sarria (universitat Ramon
Llull),Laboratori de Fisica Matematica,Societat Catalana de Fisica(I.E.C.)) | Nondimensional Simplification of Tensor Polynomials with Indices | null | null | null | null | gr-qc | null | We are presenting an algorithm capable of simplifying tensor polynomials with
indices when the building tensors have index symmetry properties. These
properties include simple symmetry, cyclicity and those due to the presence of
covariant derivatives. The algorithm is part of a Mathematica package called
Tools of Tensor Calculus (TTC) [web address: http://baldufa.upc.es/ttc]
| [
{
"created": "Wed, 15 Dec 1999 11:53:50 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Jaen",
"X.",
""
],
[
"Balfagon",
"A.",
""
]
] | We are presenting an algorithm capable of simplifying tensor polynomials with indices when the building tensors have index symmetry properties. These properties include simple symmetry, cyclicity and those due to the presence of covariant derivatives. The algorithm is part of a Mathematica package called Tools of Tensor Calculus (TTC) [web address: http://baldufa.upc.es/ttc] |
1208.6563 | Dong-han Yeom | Dong-il Hwang, Bum-Hoon Lee, Ewan D. Stewart, Dong-han Yeom, Heeseung
Zoe | Euclidean quantum gravity and stochastic inflation | 25 pages, 6 figures | Phys.Rev.D87:063502,2013 | 10.1103/PhysRevD.87.063502 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we compare dispersions of a scalar field in Euclidean quantum
gravity with stochastic inflation. We use Einstein gravity and a minimally
coupled scalar field with a quadratic potential. We restrict our attention to
small mass and small field cases. In the Euclidean approach, we introduce the
ground state wave function which is approximated by instantons. We used a
numerical technique to find instantons that satisfy classicality. In the
stochastic approach, we introduce the probability distribution of Hubble
patches that can be approximated by locally homogeneous universes down to a
smoothing scale. We assume that the ground state wave function should
correspond to the stationary state of the probability distribution of the
stochastic universe. By comparing the dispersion of both approaches, we
conclude three main results. (1) For a statistical distribution with a certain
value, we can find a corresponding instanton in the Euclidean side, and it
should be a complex-valued instanton. (2) The size of the universe of the
Euclidean approach corresponds to the smoothing scale of the stochastic side;
the universe is homogeneous up to the Euclidean instanton. (3) In addition, as
the mass increases up to a critical value, both approaches break at the same
time. Hence, generation of classical inhomogeneity in the stochastic approach
and the instability of classicality in the Euclidean approach are related.
| [
{
"created": "Fri, 31 Aug 2012 18:07:06 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Apr 2013 05:19:23 GMT",
"version": "v2"
},
{
"created": "Wed, 27 Aug 2014 01:25:18 GMT",
"version": "v3"
},
{
"created": "Fri, 12 Sep 2014 13:18:23 GMT",
"version": "v4"
}
] | 2014-09-16 | [
[
"Hwang",
"Dong-il",
""
],
[
"Lee",
"Bum-Hoon",
""
],
[
"Stewart",
"Ewan D.",
""
],
[
"Yeom",
"Dong-han",
""
],
[
"Zoe",
"Heeseung",
""
]
] | In this paper, we compare dispersions of a scalar field in Euclidean quantum gravity with stochastic inflation. We use Einstein gravity and a minimally coupled scalar field with a quadratic potential. We restrict our attention to small mass and small field cases. In the Euclidean approach, we introduce the ground state wave function which is approximated by instantons. We used a numerical technique to find instantons that satisfy classicality. In the stochastic approach, we introduce the probability distribution of Hubble patches that can be approximated by locally homogeneous universes down to a smoothing scale. We assume that the ground state wave function should correspond to the stationary state of the probability distribution of the stochastic universe. By comparing the dispersion of both approaches, we conclude three main results. (1) For a statistical distribution with a certain value, we can find a corresponding instanton in the Euclidean side, and it should be a complex-valued instanton. (2) The size of the universe of the Euclidean approach corresponds to the smoothing scale of the stochastic side; the universe is homogeneous up to the Euclidean instanton. (3) In addition, as the mass increases up to a critical value, both approaches break at the same time. Hence, generation of classical inhomogeneity in the stochastic approach and the instability of classicality in the Euclidean approach are related. |
2209.09922 | Adri\'an Del R\'io Vega | Abhay Ashtekar and Adri\'an del R\'io | Probing cosmological singularities with quantum fields: Open and closed
FLRW universes | 22 pages + 2 appendices | Phys. Rev. D 106, 085003 (2022) | 10.1103/PhysRevD.106.085003 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It was recently pointed out that linear quantum fields $\hat \phi(x)$ can be
meaningfully propagated across the big bang (and the big crunch) singularities
of spatially flat Friedmann, Lema\^itre, Robertson, Walker (FLRW) universes
\cite{ADLS2021}. Recall that $\hat \phi(x)$, as well as renormalized
observables $\langle\hat \phi(x)^2 \rangle_{ren}$ and $\langle \hat
T_{ab}(x)\rangle_{ren}$, are distribution-valued already in Minkowskian quantum
field theories. It was shown that they can be extended as well-defined
distributions even when these space-times are enlarged to include the big-bang
(or the big crunch). We generalize these results to spatially closed and open
FLRW models, showing that this `tameness' of cosmological singularities is not
an artifact of the technical simplifications due to spatial flatness. Our
analysis also provides explicit expressions of $\langle\hat \phi(x) \hat
\phi(x') \rangle_{ren}$, $\langle\hat \phi(x)^2 \rangle_{ren}$ and $\langle
\hat T_{ab}(x)\rangle_{ren}$ in closed and open universes for minimally coupled
massless scalar fields and discuss the ambiguities in the definition of
$\langle \hat T_{ab}(x)\rangle_{ren}$ at the big-bang. While the technical
expressions are more complicated than in the spatially flat case, there is also
an unexpected conceptual simplification: the infrared divergence \cite{fp} is
now absent because, in effect, the spatial curvature provides a natural cutoff.
Finally, we further clarify the sense in which quantum field theory can
continue to be well defined even though the extended space-time is not globally
hyperbolic because of the singularity, and suggest directions for further work.
| [
{
"created": "Tue, 20 Sep 2022 18:00:55 GMT",
"version": "v1"
}
] | 2022-10-12 | [
[
"Ashtekar",
"Abhay",
""
],
[
"del Río",
"Adrián",
""
]
] | It was recently pointed out that linear quantum fields $\hat \phi(x)$ can be meaningfully propagated across the big bang (and the big crunch) singularities of spatially flat Friedmann, Lema\^itre, Robertson, Walker (FLRW) universes \cite{ADLS2021}. Recall that $\hat \phi(x)$, as well as renormalized observables $\langle\hat \phi(x)^2 \rangle_{ren}$ and $\langle \hat T_{ab}(x)\rangle_{ren}$, are distribution-valued already in Minkowskian quantum field theories. It was shown that they can be extended as well-defined distributions even when these space-times are enlarged to include the big-bang (or the big crunch). We generalize these results to spatially closed and open FLRW models, showing that this `tameness' of cosmological singularities is not an artifact of the technical simplifications due to spatial flatness. Our analysis also provides explicit expressions of $\langle\hat \phi(x) \hat \phi(x') \rangle_{ren}$, $\langle\hat \phi(x)^2 \rangle_{ren}$ and $\langle \hat T_{ab}(x)\rangle_{ren}$ in closed and open universes for minimally coupled massless scalar fields and discuss the ambiguities in the definition of $\langle \hat T_{ab}(x)\rangle_{ren}$ at the big-bang. While the technical expressions are more complicated than in the spatially flat case, there is also an unexpected conceptual simplification: the infrared divergence \cite{fp} is now absent because, in effect, the spatial curvature provides a natural cutoff. Finally, we further clarify the sense in which quantum field theory can continue to be well defined even though the extended space-time is not globally hyperbolic because of the singularity, and suggest directions for further work. |
0908.2500 | Evgeny Sorkin | Evgeny Sorkin, Matthew W. Choptuik | Generalized harmonic formulation in spherical symmetry | 47 pages, 15 figures. v2: Minor corrections, including 2 added
references; journal version. | Gen.Rel.Grav.42:1239-1286,2010 | 10.1007/s10714-009-0905-8 | AEI-2009-077 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this pedagogically structured article, we describe a generalized harmonic
formulation of the Einstein equations in spherical symmetry which is regular at
the origin. The generalized harmonic approach has attracted significant
attention in numerical relativity over the past few years, especially as
applied to the problem of binary inspiral and merger. A key issue when using
the technique is the choice of the gauge source functions, and recent work has
provided several prescriptions for gauge drivers designed to evolve these
functions in a controlled way. We numerically investigate the parameter spaces
of some of these drivers in the context of fully non-linear collapse of a real,
massless scalar field, and determine nearly optimal parameter settings for
specific situations. Surprisingly, we find that many of the drivers that
perform well in 3+1 calculations that use Cartesian coordinates, are
considerably less effective in spherical symmetry, where some of them are, in
fact, unstable.
| [
{
"created": "Tue, 18 Aug 2009 07:36:41 GMT",
"version": "v1"
},
{
"created": "Fri, 30 Apr 2010 15:01:09 GMT",
"version": "v2"
}
] | 2010-05-07 | [
[
"Sorkin",
"Evgeny",
""
],
[
"Choptuik",
"Matthew W.",
""
]
] | In this pedagogically structured article, we describe a generalized harmonic formulation of the Einstein equations in spherical symmetry which is regular at the origin. The generalized harmonic approach has attracted significant attention in numerical relativity over the past few years, especially as applied to the problem of binary inspiral and merger. A key issue when using the technique is the choice of the gauge source functions, and recent work has provided several prescriptions for gauge drivers designed to evolve these functions in a controlled way. We numerically investigate the parameter spaces of some of these drivers in the context of fully non-linear collapse of a real, massless scalar field, and determine nearly optimal parameter settings for specific situations. Surprisingly, we find that many of the drivers that perform well in 3+1 calculations that use Cartesian coordinates, are considerably less effective in spherical symmetry, where some of them are, in fact, unstable. |
gr-qc/0005027 | Sawa Manoff | S. Manoff | Relative velocity and relative acceleration induced by the torsion in
(pseudo) Riemannian spaces with torsion and in spaces with an affine
connection and metrics | 35 pages | null | null | null | gr-qc | null | The influence of the torsion on the relative velocity and on the relative
acceleration between particles (points) in spaces with an affine connection and
a metric [$(L_n,g)$-spaces] and in (pseudo) Riemannian spaces with torsion
($U_n$-spaces) is considered. Necessary and sufficient conditions as well as
only necessary and only sufficient conditions for vanishing deformation, shear,
rotation and expansion are found. The notion of relative acceleration and the
related to it notions of shear, rotation and expansion accelerations induced by
the torsion are determined. It is shown that the kinematic characteristics
induced by the torsion (shear acceleration, rotation acceleration and expansion
acceleration) could play the same role as the kinematic characteristics induced
by the curvature and can (under given conditions) compensate their action as
well as the action of external forces.
The change of the rate of change of the length of a deviation vector field is
given in explicit form for $(L_n,g)$- and $U_n$-spaces.
PACS numbers: 04.90+e, 04.50+h, 12.10.Gq, 03.40.-t
| [
{
"created": "Wed, 10 May 2000 07:59:47 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Manoff",
"S.",
""
]
] | The influence of the torsion on the relative velocity and on the relative acceleration between particles (points) in spaces with an affine connection and a metric [$(L_n,g)$-spaces] and in (pseudo) Riemannian spaces with torsion ($U_n$-spaces) is considered. Necessary and sufficient conditions as well as only necessary and only sufficient conditions for vanishing deformation, shear, rotation and expansion are found. The notion of relative acceleration and the related to it notions of shear, rotation and expansion accelerations induced by the torsion are determined. It is shown that the kinematic characteristics induced by the torsion (shear acceleration, rotation acceleration and expansion acceleration) could play the same role as the kinematic characteristics induced by the curvature and can (under given conditions) compensate their action as well as the action of external forces. The change of the rate of change of the length of a deviation vector field is given in explicit form for $(L_n,g)$- and $U_n$-spaces. PACS numbers: 04.90+e, 04.50+h, 12.10.Gq, 03.40.-t |
0911.2297 | Ken-Ichi Nakao | Swastik Bhattacharya, Pankaj S. Joshi and Ken-ichi Nakao | Accelerated cosmic expansion in a scalar-field universe | 12 pages, 8 figures | Phys.Rev.D81:064032,2010 | 10.1103/PhysRevD.81.064032 | OCU-PHYS-323, AP-GR-74 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider here a spherically symmetric but inhomogeneous universe filled
with a massless scalar field. The model obeys two constraints. The first one is
that the gradient of the scalar field is timelike everywhere. The second
constraint is that the radial coordinate basis vector is a unit vector field in
the comoving coordinate system. We find that the resultant dynamical solutions
compose a one-parameter family of self-similar models which is known as the
Roberts solution. The solutions are divided into three classes. The first class
consists of solutions with only one spacelike singularity in the
synchronous-comoving chart. The second class consists of solutions with two
singularities which are null and spacelike, respectively. The third class
consists of solutions with two spacelike singularities which correspond to the
big bang and big crunch, respectively. We see that, in the first case, a
comoving volume exponentially expands as in an inflationary period; the fluid
elements are accelerated outwards form the symmetry center, even though the
strong energy condition is satisfied. This behavior is very different from that
observed in the homogeneous and isotropic universe in which the fluid elements
would move outwards with deceleration, if the strong energy conditions are
satisfied. We are thus able to achieve the accelerated expansion of the
universe for the models considered here, without a need to violate the energy
conditions. The cosmological features of the models are examined in some
detail.
| [
{
"created": "Thu, 12 Nov 2009 04:32:45 GMT",
"version": "v1"
}
] | 2011-04-20 | [
[
"Bhattacharya",
"Swastik",
""
],
[
"Joshi",
"Pankaj S.",
""
],
[
"Nakao",
"Ken-ichi",
""
]
] | We consider here a spherically symmetric but inhomogeneous universe filled with a massless scalar field. The model obeys two constraints. The first one is that the gradient of the scalar field is timelike everywhere. The second constraint is that the radial coordinate basis vector is a unit vector field in the comoving coordinate system. We find that the resultant dynamical solutions compose a one-parameter family of self-similar models which is known as the Roberts solution. The solutions are divided into three classes. The first class consists of solutions with only one spacelike singularity in the synchronous-comoving chart. The second class consists of solutions with two singularities which are null and spacelike, respectively. The third class consists of solutions with two spacelike singularities which correspond to the big bang and big crunch, respectively. We see that, in the first case, a comoving volume exponentially expands as in an inflationary period; the fluid elements are accelerated outwards form the symmetry center, even though the strong energy condition is satisfied. This behavior is very different from that observed in the homogeneous and isotropic universe in which the fluid elements would move outwards with deceleration, if the strong energy conditions are satisfied. We are thus able to achieve the accelerated expansion of the universe for the models considered here, without a need to violate the energy conditions. The cosmological features of the models are examined in some detail. |
2303.04126 | Nicolas Lecoeur | Eugeny Babichev, Christos Charmousis, Mokhtar Hassaine, Nicolas
Lecoeur | Selecting Horndeski theories without apparent symmetries and their black
hole solutions | null | null | 10.1103/PhysRevD.108.024019 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Starting from a generalised Kaluza-Klein action including arbitrary Horndeski
potentials, we establish integrability and compatibility conditions that solve
the generic field equations for spherical symmetry. The resulting theories can
be identified as general Horndeski theories having no apparent symmetries in
four dimensions or as effective string theory actions with an IR logarithmic
running for the dilaton, higher order corrections and generalised Liouville
type potentials. For such actions, we then find black holes with secondary hair
parameterized by two coupling constants essentially characterising the theories
at hand. One is related to an action which is conformally coupled in five
dimensions while the second is related to a Kaluza-Klein reduction of Lovelock
theory. We show that the full action can also be interpreted as a sum of
conformally coupled actions in differing dimensions. Known solutions are mapped
within the general chart of the found theories and novel general black holes
are discussed, focusing on their important properties and some of their
observational constraints.
| [
{
"created": "Tue, 7 Mar 2023 18:40:48 GMT",
"version": "v1"
}
] | 2023-07-26 | [
[
"Babichev",
"Eugeny",
""
],
[
"Charmousis",
"Christos",
""
],
[
"Hassaine",
"Mokhtar",
""
],
[
"Lecoeur",
"Nicolas",
""
]
] | Starting from a generalised Kaluza-Klein action including arbitrary Horndeski potentials, we establish integrability and compatibility conditions that solve the generic field equations for spherical symmetry. The resulting theories can be identified as general Horndeski theories having no apparent symmetries in four dimensions or as effective string theory actions with an IR logarithmic running for the dilaton, higher order corrections and generalised Liouville type potentials. For such actions, we then find black holes with secondary hair parameterized by two coupling constants essentially characterising the theories at hand. One is related to an action which is conformally coupled in five dimensions while the second is related to a Kaluza-Klein reduction of Lovelock theory. We show that the full action can also be interpreted as a sum of conformally coupled actions in differing dimensions. Known solutions are mapped within the general chart of the found theories and novel general black holes are discussed, focusing on their important properties and some of their observational constraints. |
2205.08831 | Miguel Manzano | Miguel Manzano and Marc Mars | General matching across Killing horizons of zero order | 38 pages, 2 figures | null | 10.1103/PhysRevD.106.044019 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Null shells are a useful geometric construction to study the propagation of
infinitesimally thin concentrations of massless particles or impulsive waves.
After recalling the necessary and sufficient conditions obtained in [28] that
allow for the matching of two spacetimes with null embedded hypersurfaces as
boundaries, we will address the problem of matching across Killing horizons of
zero order in the case when the symmetry generators are to be identified. The
results are substantially different depending on whether the boundaries are
non-degenerate or degenerate, and contain or not fixed points (in particular,
in the former case the shells have zero pressure but non-vanishing energy
density and energy flux in general). We will present the explicit form of the
so-called step function in each situation. We will then concentrate on the case
of actual Killing horizons admitting a bifurcation surface, where a complete
description of the shell and its energy-momentum tensor can be obtained. We
will conclude particularizing to the matching of two spacetimes with spherical,
plane or hyperbolic symmetry without imposing this symmetry on the shell
itself.
| [
{
"created": "Wed, 18 May 2022 09:57:48 GMT",
"version": "v1"
}
] | 2022-08-31 | [
[
"Manzano",
"Miguel",
""
],
[
"Mars",
"Marc",
""
]
] | Null shells are a useful geometric construction to study the propagation of infinitesimally thin concentrations of massless particles or impulsive waves. After recalling the necessary and sufficient conditions obtained in [28] that allow for the matching of two spacetimes with null embedded hypersurfaces as boundaries, we will address the problem of matching across Killing horizons of zero order in the case when the symmetry generators are to be identified. The results are substantially different depending on whether the boundaries are non-degenerate or degenerate, and contain or not fixed points (in particular, in the former case the shells have zero pressure but non-vanishing energy density and energy flux in general). We will present the explicit form of the so-called step function in each situation. We will then concentrate on the case of actual Killing horizons admitting a bifurcation surface, where a complete description of the shell and its energy-momentum tensor can be obtained. We will conclude particularizing to the matching of two spacetimes with spherical, plane or hyperbolic symmetry without imposing this symmetry on the shell itself. |
2008.09902 | Francisco Lobo | Francisco S. N. Lobo, Diego Rubiera-Garcia | Wormholes, energy conditions and time machines | 7 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This report is based on the Parallel Session AT3 ``Wormholes, Energy
Conditions and Time Machines'' of the Fifteenth Marcel Grossmann Meeting -
MG15, held at the University of Rome ``La Sapienza'', Rome, in 2018.
| [
{
"created": "Sat, 22 Aug 2020 19:32:53 GMT",
"version": "v1"
}
] | 2020-08-25 | [
[
"Lobo",
"Francisco S. N.",
""
],
[
"Rubiera-Garcia",
"Diego",
""
]
] | This report is based on the Parallel Session AT3 ``Wormholes, Energy Conditions and Time Machines'' of the Fifteenth Marcel Grossmann Meeting - MG15, held at the University of Rome ``La Sapienza'', Rome, in 2018. |
gr-qc/0609049 | Marcello Ortaggio | Marcello Ortaggio, Vojtech Pravda | Black rings with a small electric charge: gyromagnetic ratios and
algebraic alignment | 22 pages, 3 figures. v2: new appendix C finds the gyromagnetic ratio
g=D-2 in any dimensions, two new references. To appear in JHEP | JHEP0612:054,2006 | 10.1088/1126-6708/2006/12/054 | null | gr-qc hep-th | null | We study electromagnetic test fields in the background of vacuum black rings
using Killing vectors as vector potentials. We consider both spacetimes with a
rotating S^1 and with a rotating S^2 and we demonstrate, in particular, that
the gyromagnetic ratio of slightly charged black rings takes the value g=3
(this will in fact apply to a wider class of spacetimes). We also observe that
a S^2-rotating black ring immersed in an external "aligned" magnetic field
completely expels the magnetic flux in the extremal limit. Finally, we discuss
the mutual alignment of principal null directions of the Maxwell 2-form and of
the Weyl tensor, and the algebraic type of exact charged black rings. In
contrast to spherical black holes, charged rings display new distinctive
features and provide us with an explicit example of algebraically general (type
G) spacetimes in higher dimensions. Appendix A contains some global results on
black rings with a rotating 2-sphere. Appendix C shows that g=D-2 in any D>=4
dimensions for test electromagnetic fields generated by a time translation.
| [
{
"created": "Thu, 14 Sep 2006 11:44:51 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Dec 2006 09:38:51 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Ortaggio",
"Marcello",
""
],
[
"Pravda",
"Vojtech",
""
]
] | We study electromagnetic test fields in the background of vacuum black rings using Killing vectors as vector potentials. We consider both spacetimes with a rotating S^1 and with a rotating S^2 and we demonstrate, in particular, that the gyromagnetic ratio of slightly charged black rings takes the value g=3 (this will in fact apply to a wider class of spacetimes). We also observe that a S^2-rotating black ring immersed in an external "aligned" magnetic field completely expels the magnetic flux in the extremal limit. Finally, we discuss the mutual alignment of principal null directions of the Maxwell 2-form and of the Weyl tensor, and the algebraic type of exact charged black rings. In contrast to spherical black holes, charged rings display new distinctive features and provide us with an explicit example of algebraically general (type G) spacetimes in higher dimensions. Appendix A contains some global results on black rings with a rotating 2-sphere. Appendix C shows that g=D-2 in any D>=4 dimensions for test electromagnetic fields generated by a time translation. |
2204.03480 | Mariana Carrillo-Gonz\'alez | Jos\'e Eliel Camargo-Molina, Mariana Carrillo Gonz\'alez, Arttu
Rajantie | Phase Transitions in de Sitter: Quantum Corrections | 7 pages, double column | null | null | Imperial/TP/2022/MC/03 | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the decay rate of a false vacuum state in de Sitter space at
high Hubble rates, using two methods: the Hawking-Moss instanton method which
is fully quantum mechanical but relies on the saddle-point approximation, and
the Starobinsky-Yokoyama stochastic approach which is non-perturbative but does
not include quantum effects. We use the flux-over-population method to compute
the Hawking-Moss decay rate at one-loop order, and demonstrate that in its
domain of validity, it is reproduced by the stochastic calculation using the
one-loop constraint effective potential. This suggests that the stochastic
approach together with the constraint effective potential can be used to
accurately describe vacuum decay beyond the saddle-point approximation.
| [
{
"created": "Wed, 6 Apr 2022 14:46:16 GMT",
"version": "v1"
}
] | 2022-04-08 | [
[
"Camargo-Molina",
"José Eliel",
""
],
[
"González",
"Mariana Carrillo",
""
],
[
"Rajantie",
"Arttu",
""
]
] | We investigate the decay rate of a false vacuum state in de Sitter space at high Hubble rates, using two methods: the Hawking-Moss instanton method which is fully quantum mechanical but relies on the saddle-point approximation, and the Starobinsky-Yokoyama stochastic approach which is non-perturbative but does not include quantum effects. We use the flux-over-population method to compute the Hawking-Moss decay rate at one-loop order, and demonstrate that in its domain of validity, it is reproduced by the stochastic calculation using the one-loop constraint effective potential. This suggests that the stochastic approach together with the constraint effective potential can be used to accurately describe vacuum decay beyond the saddle-point approximation. |
2208.04596 | Saikat Chakraborty | Saikat Chakraborty, Daniele Gregoris, B. Mishra | On the uniqueness of $\Lambda$CDM-like evolution for homogeneous and
isotropic cosmology in General Relativity | 15 pages. 3 figures. Accepted for publication in PLB | PLB, 842, 137962, 2023 | 10.1016/j.physletb.2023.137962 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We address the question of the uniqueness of spatially flat $\Lambda$CDM-like
evolution for FLRW cosmologies in General Relativity, i.e. whether any model
other than the spatially flat $\Lambda$CDM can give rise to the same type of
scale factor evolution. Firstly, we elaborate on what we exactly imply by a
$\Lambda$CDM-like evolution or kinematic/cosmographic degeneracy with the
$\Lambda$CDM model, using the lessons from the statefinder diagnostic. Then, we
consider two models with interaction in the dark sector: coupled fluid-fluid
model and coupled quintessence model. We enforce the \emph{kinematic}
degeneracy with the spatially flat $\Lambda$CDM model via the cosmographic
condition $j=1$ ($j$ being the jerk parameter), which in turn fixes the
function of the interaction term that is a priori unspecified. We argue that in
General Relativity this cosmographic condition is consistent only with spatial
flatness. Employing a dynamical system approach, we show that the spatially
flat coupled fluid-fluid interacting models kinematically degenerate with
$\Lambda$CDM must necessarily be based on a phantom fluid, whereas the set of
physically viable spatially flat coupled quintessence models with power law or
exponential potential kinematically degenerate to $\Lambda$CDM is of measure
zero. Our analysis establishes that coupled fluid-fluid models with non-phantom
fluids or coupled quintessence models with power law and exponential potential
can never reproduce a cosmological evolution similar to that of the
$\Lambda$CDM. The astrophysical consequences of our findings are qualitatively
discussed in light of observational cosmological tensions.
| [
{
"created": "Tue, 9 Aug 2022 08:25:06 GMT",
"version": "v1"
},
{
"created": "Thu, 18 May 2023 17:11:20 GMT",
"version": "v2"
}
] | 2024-03-21 | [
[
"Chakraborty",
"Saikat",
""
],
[
"Gregoris",
"Daniele",
""
],
[
"Mishra",
"B.",
""
]
] | We address the question of the uniqueness of spatially flat $\Lambda$CDM-like evolution for FLRW cosmologies in General Relativity, i.e. whether any model other than the spatially flat $\Lambda$CDM can give rise to the same type of scale factor evolution. Firstly, we elaborate on what we exactly imply by a $\Lambda$CDM-like evolution or kinematic/cosmographic degeneracy with the $\Lambda$CDM model, using the lessons from the statefinder diagnostic. Then, we consider two models with interaction in the dark sector: coupled fluid-fluid model and coupled quintessence model. We enforce the \emph{kinematic} degeneracy with the spatially flat $\Lambda$CDM model via the cosmographic condition $j=1$ ($j$ being the jerk parameter), which in turn fixes the function of the interaction term that is a priori unspecified. We argue that in General Relativity this cosmographic condition is consistent only with spatial flatness. Employing a dynamical system approach, we show that the spatially flat coupled fluid-fluid interacting models kinematically degenerate with $\Lambda$CDM must necessarily be based on a phantom fluid, whereas the set of physically viable spatially flat coupled quintessence models with power law or exponential potential kinematically degenerate to $\Lambda$CDM is of measure zero. Our analysis establishes that coupled fluid-fluid models with non-phantom fluids or coupled quintessence models with power law and exponential potential can never reproduce a cosmological evolution similar to that of the $\Lambda$CDM. The astrophysical consequences of our findings are qualitatively discussed in light of observational cosmological tensions. |
2404.07723 | Lajos Di\'osi | Lajos Di\'osi | The classical-quantum hybrid canonical dynamics and its difficulties
with special and general relativity | 9pp | null | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | We discuss the Hamiltonian hybrid coupling between a classical and a quantum
subsystem. If applicable to classical gravity coupled to quantized matter, this
hybrid theory might realize a captivating `postquantum' alternative to full
quantum-gravity. We summarize the nonrelativistic hybrid dynamics in improved
formalism adequate to Hamiltonian systems. The mandatory decoherence and
diffusion terms become divergent in special and general relativistic
extensions. It is not yet known if any renormalization method might reconcile
Markovian decoherence and diffusion with relativity. Postquantum gravity could
previously only be realized in the Newtonian approximation. We argue that
pending problems of the recently proposed general relativistic postquantum
theory will not be solved if Markovian diffusion/decoherence are truly
incompatible with relativity.
| [
{
"created": "Thu, 11 Apr 2024 13:13:35 GMT",
"version": "v1"
}
] | 2024-04-12 | [
[
"Diósi",
"Lajos",
""
]
] | We discuss the Hamiltonian hybrid coupling between a classical and a quantum subsystem. If applicable to classical gravity coupled to quantized matter, this hybrid theory might realize a captivating `postquantum' alternative to full quantum-gravity. We summarize the nonrelativistic hybrid dynamics in improved formalism adequate to Hamiltonian systems. The mandatory decoherence and diffusion terms become divergent in special and general relativistic extensions. It is not yet known if any renormalization method might reconcile Markovian decoherence and diffusion with relativity. Postquantum gravity could previously only be realized in the Newtonian approximation. We argue that pending problems of the recently proposed general relativistic postquantum theory will not be solved if Markovian diffusion/decoherence are truly incompatible with relativity. |
gr-qc/0207047 | David Langlois | David Langlois (GRECO/IAP, Paris) | Gravitation and cosmology in a brane-universe | Invited review talk given at the 11th Workshop on General Relativity
and Gravitation, Waseda University, Tokyo, Japan (Jan 2002); 14 pages; Latex;
one figure | null | null | null | gr-qc astro-ph hep-ph hep-th | null | Recent theoretical developments have generated a strong interest in the
``brane-world'' picture, which assumes that ordinary matter is trapped in a
three-dimensional submanifold, usually called brane, embedded in a higher
dimensional space. The purpose of this review is to introduce some basic
results concerning gravity in these models and then to present various aspects
of the cosmology in a brane-universe.
| [
{
"created": "Thu, 11 Jul 2002 16:53:12 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Langlois",
"David",
"",
"GRECO/IAP, Paris"
]
] | Recent theoretical developments have generated a strong interest in the ``brane-world'' picture, which assumes that ordinary matter is trapped in a three-dimensional submanifold, usually called brane, embedded in a higher dimensional space. The purpose of this review is to introduce some basic results concerning gravity in these models and then to present various aspects of the cosmology in a brane-universe. |
1905.10554 | Bibhas Majhi Ranjan | Kushal Chakraborty, Bibhas Ranjan Majhi | Detector response along null geodesics in black hole spacetimes and in a
Friedmann-Lemaitre-Robertson-Walker Universe | Expanded version, to appear in Phys. Rev. D | Phys. Rev. D 100, 045004 (2019) | 10.1103/PhysRevD.100.045004 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the detector's response when moving along an ingoing null geodesic.
The backgrounds are chosen to be black hole spacetimes ($(1+1)$ dimensional
Schwarzschild metric and near horizon effective metric for any stationary black
hole in arbitrary dimensions) as well as Friedmann-Lemaitre-Robertson-Walker
(FLRW) Universe. For black holes the trajectories are defined in Schwarzschild
coordinates and the field modes are corresponding to {\it Boulware vacuum}.
Whereas for FLRW case, the detector is moving along the path defined in
original {\it cosmic time} and the field modes are related to {\it conformal
vacuum}. The analysis is done for three stages (de-Sitter, radiation dominated
and matter dominated) of the Universe. We find that, although the detector is
freely falling, it registered particles in the above mentioned respective
vacuums. We confirm this by different approaches. The detection probability
distributions, in all situations, are thermal in nature.
| [
{
"created": "Sat, 25 May 2019 08:20:32 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Jul 2019 17:30:44 GMT",
"version": "v2"
}
] | 2019-08-14 | [
[
"Chakraborty",
"Kushal",
""
],
[
"Majhi",
"Bibhas Ranjan",
""
]
] | We study the detector's response when moving along an ingoing null geodesic. The backgrounds are chosen to be black hole spacetimes ($(1+1)$ dimensional Schwarzschild metric and near horizon effective metric for any stationary black hole in arbitrary dimensions) as well as Friedmann-Lemaitre-Robertson-Walker (FLRW) Universe. For black holes the trajectories are defined in Schwarzschild coordinates and the field modes are corresponding to {\it Boulware vacuum}. Whereas for FLRW case, the detector is moving along the path defined in original {\it cosmic time} and the field modes are related to {\it conformal vacuum}. The analysis is done for three stages (de-Sitter, radiation dominated and matter dominated) of the Universe. We find that, although the detector is freely falling, it registered particles in the above mentioned respective vacuums. We confirm this by different approaches. The detection probability distributions, in all situations, are thermal in nature. |
2008.02774 | Luca Marchetti | Luca Marchetti and Daniele Oriti | Effective relational cosmological dynamics from Quantum Gravity | 31 pages, 1 figure | JHEP 05 (2021) 025 | 10.1007/JHEP05(2021)025 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the relational strategy to solve the problem of time in quantum
gravity and different ways in which it could be implemented, pointing out in
particular the fundamentally new dimension that the problem takes in a quantum
gravity context in which spacetime and geometry are understood as emergent. We
realize concretely the relational strategy we have advocated in the context of
the tensorial group field theory formalism for quantum gravity, leading to the
extraction of an effective relational cosmological dynamics from quantum
geometric models. We analyze in detail the emergent cosmological dynamics,
highlighting the improvements over previous work, the contribution of the
quantum properties of the relational clock to it, and the interplay between the
conditions ensuring a bona fide relational dynamics throughout the cosmological
evolution and the existence of a quantum bounce resolving the classical big
bang singularity.
| [
{
"created": "Thu, 6 Aug 2020 17:17:58 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Oct 2020 11:22:57 GMT",
"version": "v2"
},
{
"created": "Sun, 16 May 2021 15:14:21 GMT",
"version": "v3"
}
] | 2021-09-23 | [
[
"Marchetti",
"Luca",
""
],
[
"Oriti",
"Daniele",
""
]
] | We discuss the relational strategy to solve the problem of time in quantum gravity and different ways in which it could be implemented, pointing out in particular the fundamentally new dimension that the problem takes in a quantum gravity context in which spacetime and geometry are understood as emergent. We realize concretely the relational strategy we have advocated in the context of the tensorial group field theory formalism for quantum gravity, leading to the extraction of an effective relational cosmological dynamics from quantum geometric models. We analyze in detail the emergent cosmological dynamics, highlighting the improvements over previous work, the contribution of the quantum properties of the relational clock to it, and the interplay between the conditions ensuring a bona fide relational dynamics throughout the cosmological evolution and the existence of a quantum bounce resolving the classical big bang singularity. |
2210.01914 | Makana Silva | Makana Silva, Gabriel Vasquez, Emily Koivu, Arijit Das, and
Christopher Hirata | Corrections to Hawking Radiation from Asteroid Mass Primordial Black
Holes: I. Formalism of Dissipative Interactions in Quantum Electrodynamics | 30 pages, 1 figure | null | 10.1103/PhysRevD.107.045004 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Primordial black holes (PBHs) within the mass range $10^{17} - 10^{22}$ g are
a favorable candidate for describing the all of the dark matter content.
Towards the lower end of this mass range, the Hawking temperature, $T_{\rm H}$,
of these PBHs is $T_{\rm H} \gtrsim 100$ keV, allowing for the creation of
electron -- positron pairs; thus making their Hawking radiation a useful
constraint for most current and future MeV surveys. This motivates the need for
realistic and rigorous accounts of the distribution and dynamics of emitted
particles from Hawking radiation in order to properly model detected signals
from high energy observations. This is the first in a series of papers to
account for the $\mathcal{O}(\alpha)$ correction to the Hawking radiation
spectrum. We begin by the usual canonical quantization of the photon and spinor
(electron/positron) fields on the Schwarzschild geometry. Then we compute the
correction to the rate of emission by standard time dependent perturbation
theory from the interaction Hamiltonian. We conclude with the analytic
expression for the dissipative correction, i.e. corrections due to the creation
and annihilation of electron/positrons in the plasma.
| [
{
"created": "Tue, 4 Oct 2022 21:25:44 GMT",
"version": "v1"
}
] | 2023-02-22 | [
[
"Silva",
"Makana",
""
],
[
"Vasquez",
"Gabriel",
""
],
[
"Koivu",
"Emily",
""
],
[
"Das",
"Arijit",
""
],
[
"Hirata",
"Christopher",
""
]
] | Primordial black holes (PBHs) within the mass range $10^{17} - 10^{22}$ g are a favorable candidate for describing the all of the dark matter content. Towards the lower end of this mass range, the Hawking temperature, $T_{\rm H}$, of these PBHs is $T_{\rm H} \gtrsim 100$ keV, allowing for the creation of electron -- positron pairs; thus making their Hawking radiation a useful constraint for most current and future MeV surveys. This motivates the need for realistic and rigorous accounts of the distribution and dynamics of emitted particles from Hawking radiation in order to properly model detected signals from high energy observations. This is the first in a series of papers to account for the $\mathcal{O}(\alpha)$ correction to the Hawking radiation spectrum. We begin by the usual canonical quantization of the photon and spinor (electron/positron) fields on the Schwarzschild geometry. Then we compute the correction to the rate of emission by standard time dependent perturbation theory from the interaction Hamiltonian. We conclude with the analytic expression for the dissipative correction, i.e. corrections due to the creation and annihilation of electron/positrons in the plasma. |
2102.10813 | Nicola Maggiore | Giulio Gambuti and Nicola Maggiore | Fierz-Pauli theory reloaded: from a theory of a symmetric tensor field
to linearized massive gravity | 21 pages, no figures | Eur. Phys. J. C 81, 171 (2021) | 10.1140/epjc/s10052-021-08962-8 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Modifying gravity at large distances by means of a massive graviton may
explain the observed acceleration of the Universe without Dark Energy. The
standard paradigm for Massive Gravity is the Fierz-Pauli theory, which,
nonetheless, displays well known flaws in its massless limit. The most serious
one is represented by the vDVZ discontinuity, which consists in a disagreement
between the massless limit of the Fierz-Pauli theory and General Relativity.
Our approach is based on a field theoretical treatment of Massive Gravity:
General Relativity, in the weak field approximation, is treated as a gauge
theory of a symmetric rank-2 tensor field. This leads us to propose an
alternative theory of linearized Massive Gravity, describing five degrees of
freedom of the graviton, with a good massless limit, without vDVZ
discontinuity, and depending on one mass parameter only, in agreement with the
Fierz-Pauli theory.
| [
{
"created": "Mon, 22 Feb 2021 07:42:26 GMT",
"version": "v1"
}
] | 2021-02-23 | [
[
"Gambuti",
"Giulio",
""
],
[
"Maggiore",
"Nicola",
""
]
] | Modifying gravity at large distances by means of a massive graviton may explain the observed acceleration of the Universe without Dark Energy. The standard paradigm for Massive Gravity is the Fierz-Pauli theory, which, nonetheless, displays well known flaws in its massless limit. The most serious one is represented by the vDVZ discontinuity, which consists in a disagreement between the massless limit of the Fierz-Pauli theory and General Relativity. Our approach is based on a field theoretical treatment of Massive Gravity: General Relativity, in the weak field approximation, is treated as a gauge theory of a symmetric rank-2 tensor field. This leads us to propose an alternative theory of linearized Massive Gravity, describing five degrees of freedom of the graviton, with a good massless limit, without vDVZ discontinuity, and depending on one mass parameter only, in agreement with the Fierz-Pauli theory. |
gr-qc/9908083 | Keith H. Lockitch | John L. Friedman and Keith H. Lockitch | Gravitational-wave driven instability of rotating relativistic stars | 14 pages PTPTeX v.1.0. Contribution to proceedings of the 1999 Yukawa
International Seminar | Prog.Theor.Phys.Suppl.136:121-134,1999 | 10.1143/PTPS.136.121 | WISC-MILW-99-TH-12 | gr-qc astro-ph | null | A brief review of the stability of rotating relativistic stars is followed by
a more detailed discussion of recent work on an instability of r-modes, modes
of rotating stars that have axial parity in the slow-rotation limit. These
modes may dominate the spin-down of neutron stars that are rapidly rotating at
birth, and the gravitational waves they emit may be detectable.
| [
{
"created": "Tue, 31 Aug 1999 19:54:54 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Friedman",
"John L.",
""
],
[
"Lockitch",
"Keith H.",
""
]
] | A brief review of the stability of rotating relativistic stars is followed by a more detailed discussion of recent work on an instability of r-modes, modes of rotating stars that have axial parity in the slow-rotation limit. These modes may dominate the spin-down of neutron stars that are rapidly rotating at birth, and the gravitational waves they emit may be detectable. |
gr-qc/9711085 | Jai-chan Hwang | J. Hwang and H. Noh | Relativistic cosmological hydrodynamics | 3 pages, latex, mprocl.sty; The Eighth Marcel Grossmann Meeting on
General Relativity | null | null | null | gr-qc | null | We investigate the relativistic cosmological hydrodynamic perturbations. We
present the general large scale solutions of the perturbation variables valid
for the general sign of three space curvature, the cosmological constant, and
generally evolving background equation of state. The large scale evolution is
characterized by a conserved gauge invariant quantity which is the same as a
perturbed potential (or three-space curvature) in the comoving gauge.
| [
{
"created": "Fri, 28 Nov 1997 07:51:18 GMT",
"version": "v1"
},
{
"created": "Sat, 29 Nov 1997 07:47:09 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Hwang",
"J.",
""
],
[
"Noh",
"H.",
""
]
] | We investigate the relativistic cosmological hydrodynamic perturbations. We present the general large scale solutions of the perturbation variables valid for the general sign of three space curvature, the cosmological constant, and generally evolving background equation of state. The large scale evolution is characterized by a conserved gauge invariant quantity which is the same as a perturbed potential (or three-space curvature) in the comoving gauge. |
1212.1006 | Francisco Lobo | Francisco S. N. Lobo | Time machines and traversable wormholes in modified theories of gravity | 5 pages, 2 figures; contribution to the proceedings of The Time
Machine Factory, Turin, Italy, 14-20 October, 2012 | EPJ Web Conf. 58 (2013) 01006 | 10.1051/epjconf/20135801006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review recent work on wormhole geometries in the context of modified
theories of gravity, in particular, in f(R) gravity and with a nonminimal
curvature-matter coupling, and in the recently proposed hybrid metric-Palatini
theory. In principle, the normal matter threading the throat can be shown to
satisfy the energy conditions and it is the higher order curvatures terms that
sustain these wormhole geometries. We also briefly review the conversion of
wormholes into time-machines, explore several of the time travel paradoxes and
possible remedies to these intriguing side-effects in wormhole physics.
| [
{
"created": "Wed, 5 Dec 2012 12:29:11 GMT",
"version": "v1"
}
] | 2013-10-18 | [
[
"Lobo",
"Francisco S. N.",
""
]
] | We review recent work on wormhole geometries in the context of modified theories of gravity, in particular, in f(R) gravity and with a nonminimal curvature-matter coupling, and in the recently proposed hybrid metric-Palatini theory. In principle, the normal matter threading the throat can be shown to satisfy the energy conditions and it is the higher order curvatures terms that sustain these wormhole geometries. We also briefly review the conversion of wormholes into time-machines, explore several of the time travel paradoxes and possible remedies to these intriguing side-effects in wormhole physics. |
1905.09913 | Mar\'ia Jos\'e Guzm\'an | Cecilia Bejarano, Rafael Ferraro, Franco Fiorini, Mar\'ia Jos\'e
Guzm\'an | Reflections on the covariance of modified teleparallel theories of
gravity | 12 pages, no figures; contribution to the proceedings of the workshop
"Teleparallel Universes in Salamanca" | Universe 5 (2019) no.6, 158 | 10.3390/universe5060158 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We review the current status of the Lorentz covariance in teleparallel and
modified teleparallel theories of gravity, and discuss the controversial
features of the different approaches. We also revisit the issue of the remnant
Lorentz gauge symmetries in $f(T)$ gravity.
| [
{
"created": "Thu, 23 May 2019 20:37:22 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Jun 2019 21:48:59 GMT",
"version": "v2"
}
] | 2019-07-05 | [
[
"Bejarano",
"Cecilia",
""
],
[
"Ferraro",
"Rafael",
""
],
[
"Fiorini",
"Franco",
""
],
[
"Guzmán",
"María José",
""
]
] | We review the current status of the Lorentz covariance in teleparallel and modified teleparallel theories of gravity, and discuss the controversial features of the different approaches. We also revisit the issue of the remnant Lorentz gauge symmetries in $f(T)$ gravity. |
gr-qc/9410015 | Renaud Parentani | Renaud Parentani, Joseph Katz and Isao Okamoto | Thermodynamics of a black hole in a cavity | 27 pages, latex file, contains 3 figures available on request at
okamoto@gprx.miz.nao.ac.jp | Class.Quant.Grav.12:1663-1684,1995 | 10.1088/0264-9381/12/7/009 | null | gr-qc | null | We present a unified thermodynamical description of the configurations
consisting on self-gravitating radiation with or without a black hole. We
compute the thermal fluctuations and evaluate where will they induce a
transition from metastable configurations towards stable ones. We show that the
probability of finding such a transition is exponentially small. This indicates
that, in a sequence of quasi equilibrium configurations, the system will remain
in the metastable states till it approaches very closely the critical point
beyond which no metastable configuration exists. Near that point, we relate the
divergence of the local temperature fluctuations to the approach of the
instability of the whole system, thereby generalizing the usual fluctuations
analysis in the cases where long range forces are present. When angular
momentum is added to the cavity, the above picture is slightly modified.
Nevertheless, at high angular momentum, the black hole loses most of its mass
before it reaches the critical point at which it evaporates completely.
| [
{
"created": "Wed, 12 Oct 1994 11:19:00 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Parentani",
"Renaud",
""
],
[
"Katz",
"Joseph",
""
],
[
"Okamoto",
"Isao",
""
]
] | We present a unified thermodynamical description of the configurations consisting on self-gravitating radiation with or without a black hole. We compute the thermal fluctuations and evaluate where will they induce a transition from metastable configurations towards stable ones. We show that the probability of finding such a transition is exponentially small. This indicates that, in a sequence of quasi equilibrium configurations, the system will remain in the metastable states till it approaches very closely the critical point beyond which no metastable configuration exists. Near that point, we relate the divergence of the local temperature fluctuations to the approach of the instability of the whole system, thereby generalizing the usual fluctuations analysis in the cases where long range forces are present. When angular momentum is added to the cavity, the above picture is slightly modified. Nevertheless, at high angular momentum, the black hole loses most of its mass before it reaches the critical point at which it evaporates completely. |
1608.06540 | Ruben Cordero | Ruben Cordero, Eduardo L. Gonzalez and Alfonso Queijeiro | An equation of state for purely kinetic k-essence inspired by cosmic
topological defects | 19 pages, 13 figures, typos corrected and references added | null | 10.1140/epjc/s10052-017-4913-7 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the physical properties of a purely kinetic k-essence model
with an equation of state motivated in superconducting membranes. We compute
the equation of state parameter $w$ and discuss its physical evolution via a
nonlinear equation of state. Using the adiabatic speed of sound and energy
density, we restrict the range of parameters of the model in order to have an
acceptable physical behavior. Furthermore, we analyze the evolution of the
luminosity distance $d_{L}$ with redshift $z$ by comparing (normalizing) it
with the $\Lambda$CDM model. Since the equation of state parameter is
$z$-dependent the evolution of the luminosity distance is also analyzed using
the Alcock-Paczy\'{n}ski test.
| [
{
"created": "Mon, 15 Aug 2016 18:59:25 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Sep 2016 15:41:28 GMT",
"version": "v2"
}
] | 2017-08-02 | [
[
"Cordero",
"Ruben",
""
],
[
"Gonzalez",
"Eduardo L.",
""
],
[
"Queijeiro",
"Alfonso",
""
]
] | We investigate the physical properties of a purely kinetic k-essence model with an equation of state motivated in superconducting membranes. We compute the equation of state parameter $w$ and discuss its physical evolution via a nonlinear equation of state. Using the adiabatic speed of sound and energy density, we restrict the range of parameters of the model in order to have an acceptable physical behavior. Furthermore, we analyze the evolution of the luminosity distance $d_{L}$ with redshift $z$ by comparing (normalizing) it with the $\Lambda$CDM model. Since the equation of state parameter is $z$-dependent the evolution of the luminosity distance is also analyzed using the Alcock-Paczy\'{n}ski test. |
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