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1508.04697
Mohammad Malekjani
Mohammad Malekjani, Tayebe Naderi and Francesco Pace
Effects of ghost dark energy perturbations on the evolution of spherical overdensities
Accepted for publication in MNRAS
MNRAS 453, 4148 (2015)
10.1093/mnras/stv1909
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
While in the standard cosmological model the accelerated expansion of the Universe is explained by invoking the presence of the cosmological constant term, it is still unclear the true origin of this stunning observational fact. It is therefore interesting to explore alternatives to the simplest scenario, in particul...
[ { "created": "Tue, 18 Aug 2015 10:54:08 GMT", "version": "v1" } ]
2015-10-07
[ [ "Malekjani", "Mohammad", "" ], [ "Naderi", "Tayebe", "" ], [ "Pace", "Francesco", "" ] ]
While in the standard cosmological model the accelerated expansion of the Universe is explained by invoking the presence of the cosmological constant term, it is still unclear the true origin of this stunning observational fact. It is therefore interesting to explore alternatives to the simplest scenario, in particular...
1910.11970
Daniel Berkowitz
Daniel Berkowitz
New Solutions To The Bianchi IX Wheeler DeWitt Equation And Leading Order Solutions For $\Lambda$ $\ne$ 0 And A Primordial Magnetic Field
null
null
null
null
gr-qc math-ph math.MP quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
New closed form solutions to the Lorentzian signature symmetry reduced Bianchi IX Wheeler DeWitt equation are obtained using a Euclidean-signature semi classical method for Hartle Hawking ordering parameters $ \pm 2\sqrt{33} $ for the wormhole Hamilton-Jacobi solution. Moving past the wormhole case we also compute fi...
[ { "created": "Sat, 26 Oct 2019 00:50:00 GMT", "version": "v1" } ]
2019-10-29
[ [ "Berkowitz", "Daniel", "" ] ]
New closed form solutions to the Lorentzian signature symmetry reduced Bianchi IX Wheeler DeWitt equation are obtained using a Euclidean-signature semi classical method for Hartle Hawking ordering parameters $ \pm 2\sqrt{33} $ for the wormhole Hamilton-Jacobi solution. Moving past the wormhole case we also compute firs...
1707.06747
Chikun Ding
Chikun Ding
Quasinormal ringing of black holes in Einstein aether theory
9 firgures, 4tables, 4 pages and 2 appendix added. Accepted for publication in Phys. Rev. D. arXiv admin note: text overlap with arXiv:gr-qc/0701089 by other authors
Phys. Rev. D 96, 104021 (2017)
10.1103/PhysRevD.96.104021
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The gravitational consequence of local Lorentz violation (LV) should show itself in derivation of the characteristic quasinormal ringing of black hole mergers from their general relativity case. In this paper, we study quasinormal modes (QNMs) of the scalar and electromagnetic field perturbations to Einstein aether b...
[ { "created": "Fri, 21 Jul 2017 03:24:01 GMT", "version": "v1" }, { "created": "Tue, 24 Oct 2017 00:23:12 GMT", "version": "v2" } ]
2017-11-22
[ [ "Ding", "Chikun", "" ] ]
The gravitational consequence of local Lorentz violation (LV) should show itself in derivation of the characteristic quasinormal ringing of black hole mergers from their general relativity case. In this paper, we study quasinormal modes (QNMs) of the scalar and electromagnetic field perturbations to Einstein aether bla...
2211.13616
Josef Seitz
Josef Seitz (Arnold-Sommerfeld-Center, Munich, Germany)
De Sitter and Minkowski Solutions in 4+1 Brane-World Models
6 pages
null
null
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We comment on approaches to the Cosmological Constant Problem in 4+1 dimensions, with the Standard Model fields confined to a 3-brane. We show that requiring maximal 4D symmetry only on this 3-brane (and not on all other 3-branes that foliate the 4+1-dimensional space) leads to a wide class of de Sitter solutions on ...
[ { "created": "Thu, 24 Nov 2022 14:06:19 GMT", "version": "v1" } ]
2022-11-28
[ [ "Seitz", "Josef", "", "Arnold-Sommerfeld-Center, Munich, Germany" ] ]
We comment on approaches to the Cosmological Constant Problem in 4+1 dimensions, with the Standard Model fields confined to a 3-brane. We show that requiring maximal 4D symmetry only on this 3-brane (and not on all other 3-branes that foliate the 4+1-dimensional space) leads to a wide class of de Sitter solutions on th...
gr-qc/0111061
Navin Singh
S.C. Tiwari
Time and Cosmic Clock
Prepared for Gravity Research Foundation Award 2001. Report IONP-5-2001
null
null
null
gr-qc
null
The nature of time vis-a-vis relativity is critically examined. Based on the author's space-time interaction hypothesis of late 1970's, cosmological model with time-varying velocity of light is discussed.
[ { "created": "Tue, 20 Nov 2001 08:00:44 GMT", "version": "v1" } ]
2007-05-23
[ [ "Tiwari", "S. C.", "" ] ]
The nature of time vis-a-vis relativity is critically examined. Based on the author's space-time interaction hypothesis of late 1970's, cosmological model with time-varying velocity of light is discussed.
2101.07566
David Benisty
David Benisty, David Vasak, Johannes Kirsch, Jurgen Struckmeier
Low-Redshift Constraints on Covariant Canonical Gauge Theory of Gravity
9 pages; 5 figures
Eur. Phys. J. C81 (2021) 125
10.1140/epjc/s10052-021-08924-0
null
gr-qc astro-ph.CO hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Constraints on the Covariant Canonical Gauge Gravity (CCGG) theory from low-redshift cosmology are studied. The formulation extends Einstein's theory of General Relativity (GR) by a quadratic Riemann-Cartan term in the Lagrangian, controlled by a "deformation" parameter. In the Friedman universe this leads to an addi...
[ { "created": "Tue, 19 Jan 2021 11:21:14 GMT", "version": "v1" } ]
2021-02-09
[ [ "Benisty", "David", "" ], [ "Vasak", "David", "" ], [ "Kirsch", "Johannes", "" ], [ "Struckmeier", "Jurgen", "" ] ]
Constraints on the Covariant Canonical Gauge Gravity (CCGG) theory from low-redshift cosmology are studied. The formulation extends Einstein's theory of General Relativity (GR) by a quadratic Riemann-Cartan term in the Lagrangian, controlled by a "deformation" parameter. In the Friedman universe this leads to an additi...
1110.3020
Francesca Vidotto
Enrique F. Borja, I\~naki Garay, Francesca Vidotto
Learning about Quantum Gravity with a Couple of Nodes
null
SIGMA 8 (2012), 015, 44 pages
10.3842/SIGMA.2012.015
null
gr-qc
http://creativecommons.org/licenses/by-nc-sa/3.0/
Loop Quantum Gravity provides a natural truncation of the infinite degrees of freedom of gravity, obtained by studying the theory on a given finite graph. We review this procedure and we present the construction of the canonical theory on a simple graph, formed by only two nodes. We review the U(N) framework, which p...
[ { "created": "Thu, 13 Oct 2011 18:11:35 GMT", "version": "v1" }, { "created": "Tue, 24 Jan 2012 13:56:10 GMT", "version": "v2" }, { "created": "Mon, 12 Mar 2012 10:10:56 GMT", "version": "v3" }, { "created": "Sun, 25 Mar 2012 07:26:43 GMT", "version": "v4" } ]
2012-03-27
[ [ "Borja", "Enrique F.", "" ], [ "Garay", "Iñaki", "" ], [ "Vidotto", "Francesca", "" ] ]
Loop Quantum Gravity provides a natural truncation of the infinite degrees of freedom of gravity, obtained by studying the theory on a given finite graph. We review this procedure and we present the construction of the canonical theory on a simple graph, formed by only two nodes. We review the U(N) framework, which pro...
1410.8281
Supriya Pan
Supriya Pan and Subenoy Chakraborty
A cosmographic analysis of holographic dark energy models
13 pages, 20 figures
Int. J. Mod. Phys. D Vol. 23, No. 11 (2014) 1450092
10.1142/S0218271814500928
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The present work deals with a detailed study of interacting holographic dark energy model for three common choices of the interaction term. Also, two standard choices of IR cut-off, namely, Ricci length scale and radius of the event horizon are considered here. Finally, the cosmographic parameters are presented both ...
[ { "created": "Thu, 30 Oct 2014 07:51:23 GMT", "version": "v1" }, { "created": "Mon, 10 Nov 2014 08:06:08 GMT", "version": "v2" } ]
2014-11-11
[ [ "Pan", "Supriya", "" ], [ "Chakraborty", "Subenoy", "" ] ]
The present work deals with a detailed study of interacting holographic dark energy model for three common choices of the interaction term. Also, two standard choices of IR cut-off, namely, Ricci length scale and radius of the event horizon are considered here. Finally, the cosmographic parameters are presented both an...
2404.07244
V. G. Gurzadyan
M. Samsonyan, A.A. Kocharyan, V.G. Gurzadyan
Smearing of primordial gravitational waves
8 pages, 4 figs; Eur Phys J Plus (in press)
Eur. Phys. J. Plus, 139, 317 (2024)
10.1140/epjp/s13360-024-05097-z
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A mechanism for smearing of the primordial gravitational waves during the radiation-dominated phase of the evolution of the Universe is considered. It is shown that the primordial gravitational waves can possess hyperbolicity features due to their propagation through the matter inhomogeneities. This mechanism of smea...
[ { "created": "Wed, 10 Apr 2024 02:51:01 GMT", "version": "v1" } ]
2024-04-15
[ [ "Samsonyan", "M.", "" ], [ "Kocharyan", "A. A.", "" ], [ "Gurzadyan", "V. G.", "" ] ]
A mechanism for smearing of the primordial gravitational waves during the radiation-dominated phase of the evolution of the Universe is considered. It is shown that the primordial gravitational waves can possess hyperbolicity features due to their propagation through the matter inhomogeneities. This mechanism of smeari...
1603.09671
Parampreet Singh
David Craig, Parampreet Singh
The Vertex Expansion in the Consistent Histories Formulation of Spin Foam Loop Quantum Cosmology
6 pages. To appear in Proceedings of the Fourteenth Marcel Grossman Meeting on General Relativity
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Assignment of consistent quantum probabilities to events in a quantum universe is a fundamental challenge which every quantum cosmology/gravity framework must overcome. In loop quantum cosmology, this issue leads to a fundamental question: What is the probability that the universe undergoes a non-singular bounce? Usi...
[ { "created": "Thu, 31 Mar 2016 16:31:30 GMT", "version": "v1" } ]
2016-04-01
[ [ "Craig", "David", "" ], [ "Singh", "Parampreet", "" ] ]
Assignment of consistent quantum probabilities to events in a quantum universe is a fundamental challenge which every quantum cosmology/gravity framework must overcome. In loop quantum cosmology, this issue leads to a fundamental question: What is the probability that the universe undergoes a non-singular bounce? Using...
0909.2330
Laura Mersini-Houghton
L.Mersini-Houghton
Notes on Time's Enigma
6pgs, Talk given at FQXI conference, Azores, 2009; to appear in 'Time's Arrow' book, Springer
null
null
null
gr-qc hep-ph hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Scientists continue to wrestle with the enigma of time. Is time a dynamic or a fundamental property of spacetime? Why does it have an arrow pointing from past to future? Why are physical laws time-symmetric in a universe with broken time-reversal symmetry? These questions remain a mystery. The hope has been that an u...
[ { "created": "Sat, 12 Sep 2009 12:59:51 GMT", "version": "v1" } ]
2009-09-15
[ [ "Mersini-Houghton", "L.", "" ] ]
Scientists continue to wrestle with the enigma of time. Is time a dynamic or a fundamental property of spacetime? Why does it have an arrow pointing from past to future? Why are physical laws time-symmetric in a universe with broken time-reversal symmetry? These questions remain a mystery. The hope has been that an und...
gr-qc/0309085
Stephane Fay
Stephane Fay
Hamiltonian study of the Generalized scalar-tensor theory with potential in a Bianchi type I model
15 pages
Class.Quant.Grav. 17 (2000) 891-902
10.1088/0264-9381/17/4/310
null
gr-qc
null
We study the generalized scalar tensor theory with a potential in the Bianchi type I model by using the ADM formalism. We examine the conditions for the Universe to be in expansion, isotropic and with a positive potential at late time in the Brans-Dicke and Einstein frames. In particular, we analyse the two important...
[ { "created": "Thu, 18 Sep 2003 11:35:43 GMT", "version": "v1" } ]
2009-11-10
[ [ "Fay", "Stephane", "" ] ]
We study the generalized scalar tensor theory with a potential in the Bianchi type I model by using the ADM formalism. We examine the conditions for the Universe to be in expansion, isotropic and with a positive potential at late time in the Brans-Dicke and Einstein frames. In particular, we analyse the two important c...
gr-qc/0302036
Gaetano Vilasi
F. Canfora, G. Vilasi
Trace anomaly and black holes evaporation
null
null
null
null
gr-qc hep-th
null
A model is proposed to describe a transition from a Schwarzschild black hole of mass $M_{0}$ to a Schwarzschild black hole of mass $M_{1}$ $\leq M_{0}$. The basic equations are derived from the non-vacuum Einstein field equations taking a source representing a null scalar field with a nonvanishing trace anomaly. It i...
[ { "created": "Mon, 10 Feb 2003 21:53:56 GMT", "version": "v1" }, { "created": "Thu, 13 Feb 2003 22:04:35 GMT", "version": "v2" }, { "created": "Mon, 5 May 2003 17:17:25 GMT", "version": "v3" } ]
2007-05-23
[ [ "Canfora", "F.", "" ], [ "Vilasi", "G.", "" ] ]
A model is proposed to describe a transition from a Schwarzschild black hole of mass $M_{0}$ to a Schwarzschild black hole of mass $M_{1}$ $\leq M_{0}$. The basic equations are derived from the non-vacuum Einstein field equations taking a source representing a null scalar field with a nonvanishing trace anomaly. It is ...
0904.0066
D. V. Ahluwalia
D. V. Ahluwalia
Towards a relativity of dark-matter rods and clocks
Revised version with minor changes. This essay received an "honorable mention" in the 2009 Essay Competition of the Gravity Research Foundation. Submitted to IJMPD Special Issue
Int. J. Mod. Phys. D18:2311-2316, 2009
10.1142/S0218271809015850
null
gr-qc astro-ph.CO hep-ph hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the absence of dark matter, the dynamical and kinematical interpretations of the special relativistic spacetime have been and still are the topic of philosophic debate, which whilst fertile, is by and large of little predictive power. This changes dramatically if the debate includes a dark matter candidate in a "n...
[ { "created": "Wed, 1 Apr 2009 18:59:04 GMT", "version": "v1" }, { "created": "Wed, 20 May 2009 03:27:56 GMT", "version": "v2" }, { "created": "Sun, 25 Oct 2009 06:16:07 GMT", "version": "v3" } ]
2011-06-16
[ [ "Ahluwalia", "D. V.", "" ] ]
In the absence of dark matter, the dynamical and kinematical interpretations of the special relativistic spacetime have been and still are the topic of philosophic debate, which whilst fertile, is by and large of little predictive power. This changes dramatically if the debate includes a dark matter candidate in a "non...
2309.14472
Christopher Alexander
Christopher Alexander, Blake Temple and Joel Smoller
Shock-Wave Refinement of the Friedmann-Robertson-Walker Metric
null
null
null
null
gr-qc math-ph math.MP
http://creativecommons.org/licenses/by/4.0/
The mathematics of general relativistic shock waves is introduced and considered in a cosmological context. In particular, an expanding Friedmann-Roberson-Walker metric is matched to a Tolman-Oppenheimer-Volkoff metric across a spherical shock surface. This is the general relativistic analogue of a shock-wave explosi...
[ { "created": "Mon, 25 Sep 2023 19:14:13 GMT", "version": "v1" } ]
2023-09-27
[ [ "Alexander", "Christopher", "" ], [ "Temple", "Blake", "" ], [ "Smoller", "Joel", "" ] ]
The mathematics of general relativistic shock waves is introduced and considered in a cosmological context. In particular, an expanding Friedmann-Roberson-Walker metric is matched to a Tolman-Oppenheimer-Volkoff metric across a spherical shock surface. This is the general relativistic analogue of a shock-wave explosion...
0903.4144
Gilberto Medeiros Kremer
Luis P. Chimento, Monica Forte, Gilberto M. Kremer, Martin G. Richarte
Tachyon and Quintessence Brane-World Universe
8 pages. Version accepted for publication in Physical Review D
Phys.Rev.D79:083527,2009
10.1103/PhysRevD.79.083527
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Using tachyon or quintessence fields along with a barotropic fluid on the brane we examine the different cosmological stages in a Friedmann-Robertson-Walker(FRW) universe, from the first radiation scenario to the later era dominated by cosmic string networks. We introduce a new algorithm to generalize previous works ...
[ { "created": "Tue, 24 Mar 2009 17:49:18 GMT", "version": "v1" }, { "created": "Wed, 24 Jun 2009 07:08:26 GMT", "version": "v2" } ]
2011-08-11
[ [ "Chimento", "Luis P.", "" ], [ "Forte", "Monica", "" ], [ "Kremer", "Gilberto M.", "" ], [ "Richarte", "Martin G.", "" ] ]
Using tachyon or quintessence fields along with a barotropic fluid on the brane we examine the different cosmological stages in a Friedmann-Robertson-Walker(FRW) universe, from the first radiation scenario to the later era dominated by cosmic string networks. We introduce a new algorithm to generalize previous works on...
0711.4415
J. Ponce de Leon
J. Ponce de Leon
Static exteriors for nonstatic braneworld stars
Some Editorial changes and references added to the boundary conditions section. Accepted for publication in Classical and Quantum Gravity
Class.Quant.Grav.25:075012,2008
10.1088/0264-9381/25/7/075012
null
gr-qc
null
We study possible static non-Schwarzschild exteriors for nonstatic spherically symmetric stars in a Randall $&$ Sundrum type II braneworld scenario. Thus, the vacuum region outside the surface of a star is assumed to be a static solution to the equation $^{(4)}R = 0$, where $^{(4)}R $ is the scalar curvature of the 4...
[ { "created": "Wed, 28 Nov 2007 03:49:08 GMT", "version": "v1" }, { "created": "Tue, 4 Mar 2008 05:24:11 GMT", "version": "v2" } ]
2008-11-26
[ [ "de Leon", "J. Ponce", "" ] ]
We study possible static non-Schwarzschild exteriors for nonstatic spherically symmetric stars in a Randall $&$ Sundrum type II braneworld scenario. Thus, the vacuum region outside the surface of a star is assumed to be a static solution to the equation $^{(4)}R = 0$, where $^{(4)}R $ is the scalar curvature of the 4-d...
1807.00434
Federico Di Gioia
Federico Di Gioia and Giovanni Montani
Linear perturbations of an anisotropic Bianchi I model with a uniform magnetic field
Small modifications. Final version, published by EPJC
Eur. Phys. J. C (2019) 79: 921
10.1140/epjc/s10052-019-7411-2
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this work, we study the effect of a magnetic field on the growth of cosmological perturbations. We develop a mathematical consistent treatment in which a perfect fluid and a uniform magnetic field evolve together in a Bianchi I universe. We then study the energy density perturbations on this background with partic...
[ { "created": "Mon, 2 Jul 2018 02:11:12 GMT", "version": "v1" }, { "created": "Thu, 12 Jul 2018 12:30:48 GMT", "version": "v2" }, { "created": "Wed, 26 Jun 2019 15:35:54 GMT", "version": "v3" }, { "created": "Sun, 17 Nov 2019 15:16:36 GMT", "version": "v4" } ]
2019-11-19
[ [ "Di Gioia", "Federico", "" ], [ "Montani", "Giovanni", "" ] ]
In this work, we study the effect of a magnetic field on the growth of cosmological perturbations. We develop a mathematical consistent treatment in which a perfect fluid and a uniform magnetic field evolve together in a Bianchi I universe. We then study the energy density perturbations on this background with particul...
2211.13477
Ken-Ichi Nakao
Ken-ichi Nakao, Kazumasa Okabayashi and Tomohiro Harada
Radiative gravastar with thermal spectrum; Sudden vacuum condensation without gravitational collapse
22 pages, 2 figures. arXiv admin note: text overlap with arXiv:2203.14519. Discussions about the temperature of the radiation are added in the revised version
null
10.1103/PhysRevD.107.084036
AP-GR-186, NITEP 150, YITP-22-141, RUP-22-24
gr-qc
http://creativecommons.org/licenses/by/4.0/
The gravastar is an exotic compact object proposed as a final product of gravitational collapse of a massive object in order to resolve problems associated with black holes. It is enclosed by a thin crust and the inside of it is occupied by the positive cosmological constant. Recently, the present authors studied qua...
[ { "created": "Thu, 24 Nov 2022 08:51:09 GMT", "version": "v1" }, { "created": "Mon, 5 Dec 2022 03:42:35 GMT", "version": "v2" } ]
2023-05-03
[ [ "Nakao", "Ken-ichi", "" ], [ "Okabayashi", "Kazumasa", "" ], [ "Harada", "Tomohiro", "" ] ]
The gravastar is an exotic compact object proposed as a final product of gravitational collapse of a massive object in order to resolve problems associated with black holes. It is enclosed by a thin crust and the inside of it is occupied by the positive cosmological constant. Recently, the present authors studied quant...
2407.01736
Surajit Kalita
Surajit Kalita
Constraining Fundamental Constants with Fast Radio Bursts: Unveiling the Role of Energy Scale
7 pages with 3 figures and 1 table; accepted for publication in MNRAS Letters
MNRAS: Letters 533 (2024) L57
10.1093/mnrasl/slae062
null
gr-qc astro-ph.CO astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Understanding physical mechanisms relies on the accurate determination of fundamental constants, although inherent limitations in experimental techniques introduce uncertainties into these measurements. This paper explores the uncertainties associated with measuring the fine-structure constant ($\alpha$) and the prot...
[ { "created": "Mon, 1 Jul 2024 19:11:28 GMT", "version": "v1" } ]
2024-07-11
[ [ "Kalita", "Surajit", "" ] ]
Understanding physical mechanisms relies on the accurate determination of fundamental constants, although inherent limitations in experimental techniques introduce uncertainties into these measurements. This paper explores the uncertainties associated with measuring the fine-structure constant ($\alpha$) and the proton...
2105.13529
Abhik Kumar Sanyal Dr.
Abhik Kumar Sanyal, Bijan Modak and Manas Chakrabortty
New conserved tensors and Brans-Dicke type field equation, using integrability condition
14 pages, 0 figures
International Journal of Geometric Methods in Modern Physics, (2022) 2250058 (19 pages)
10.1142/S021988782250058X
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We explore some new off-shell and on-shell conserved quantities for a scalar field in Minkowski space, using integrability condition. The off-shell conserved tensors are related to the kinematics of the field, while a linear combination of the off-shell and the on-shell conserved tensors ends up with the energy-momen...
[ { "created": "Fri, 28 May 2021 01:05:07 GMT", "version": "v1" }, { "created": "Thu, 20 Jan 2022 15:05:34 GMT", "version": "v2" } ]
2022-01-21
[ [ "Sanyal", "Abhik Kumar", "" ], [ "Modak", "Bijan", "" ], [ "Chakrabortty", "Manas", "" ] ]
We explore some new off-shell and on-shell conserved quantities for a scalar field in Minkowski space, using integrability condition. The off-shell conserved tensors are related to the kinematics of the field, while a linear combination of the off-shell and the on-shell conserved tensors ends up with the energy-momentu...
gr-qc/0403079
Alexander I. Nesterov
Alexander I. Nesterov
Topology change in (2+1)-dimensional gravity with non-Abelian Higgs field
This essay was selected for an Honorable Mention by the Gravity Research Foundation, 1996
Gen.Rel.Grav. 29 (1997) 1115-1122
10.1023/A:1018839108338
null
gr-qc hep-th math-ph math.GT math.MP
null
We study topology change in (2+1)D gravity coupling with non-Abelian SO(2,1) Higgs field from the point of view of Morse theory. It is shown that the Higgs potential can be identified as a Morse function. The critical points of the latter (i.e. loci of change of the spacetime topology) coincide with zeros of the Higg...
[ { "created": "Thu, 18 Mar 2004 03:15:04 GMT", "version": "v1" } ]
2013-01-15
[ [ "Nesterov", "Alexander I.", "" ] ]
We study topology change in (2+1)D gravity coupling with non-Abelian SO(2,1) Higgs field from the point of view of Morse theory. It is shown that the Higgs potential can be identified as a Morse function. The critical points of the latter (i.e. loci of change of the spacetime topology) coincide with zeros of the Higgs ...
1909.07959
Raihaneh Moti
R. Moti and A. Shojai
Geodesic congruences in quantum improved spacetimes
null
Phys. Rev. D 101, 064013 (2020)
10.1103/PhysRevD.101.064013
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We investigate the geodesic deviation equation in the context of quantum improved spacetimes. The improved Raychaudhuri equation is derived, and it is shown that the classical strong energy condition does not necessarily lead to the convergence of geodesics in a congruence in the quantum improved spacetime.
[ { "created": "Tue, 17 Sep 2019 17:50:16 GMT", "version": "v1" }, { "created": "Wed, 6 Nov 2019 13:49:41 GMT", "version": "v2" }, { "created": "Thu, 20 Feb 2020 16:59:26 GMT", "version": "v3" } ]
2020-03-11
[ [ "Moti", "R.", "" ], [ "Shojai", "A.", "" ] ]
We investigate the geodesic deviation equation in the context of quantum improved spacetimes. The improved Raychaudhuri equation is derived, and it is shown that the classical strong energy condition does not necessarily lead to the convergence of geodesics in a congruence in the quantum improved spacetime.
2012.04997
Nikolay Fimin N
N.N. Fimin, V.M. Chechetkin
The modified Newton attraction law and its connection with cosmological $\Lambda$--term
null
null
10.1140/epjp/s13360-020-01002-6
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider the possibility of generalizing the Newtonian law of gravity and the transition to a general relativistic model for weak fields with the inclusion of a repulsive term identified as a cosmological constant. The analysis includes that of the test particle's motion in a modified gravitational field of the Hi...
[ { "created": "Wed, 9 Dec 2020 12:04:12 GMT", "version": "v1" } ]
2020-12-10
[ [ "Fimin", "N. N.", "" ], [ "Chechetkin", "V. M.", "" ] ]
We consider the possibility of generalizing the Newtonian law of gravity and the transition to a general relativistic model for weak fields with the inclusion of a repulsive term identified as a cosmological constant. The analysis includes that of the test particle's motion in a modified gravitational field of the Hilb...
1606.06967
Nicholas Tsamis
N. C. Tsamis and R. P. Woodard
An Improved Cosmological Model
22 pages, 9 figures, uses latex 2e
Phys. Rev. D 94, 043508 (2016)
10.1103/PhysRevD.94.043508
UFIFT-QG-16-07, CCTP-2016-09, CCQCN-2016-146, ITCP-IPP 2016/07
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study a class of non-local, action-based, and purely gravitational models. These models seek to describe a cosmology in which inflation is driven by a large, bare cosmological constant that is screened by the self-gravitation between the soft gravitons that inflation rips from the vacuum. Inflation ends with the u...
[ { "created": "Wed, 22 Jun 2016 14:47:56 GMT", "version": "v1" } ]
2016-08-17
[ [ "Tsamis", "N. C.", "" ], [ "Woodard", "R. P.", "" ] ]
We study a class of non-local, action-based, and purely gravitational models. These models seek to describe a cosmology in which inflation is driven by a large, bare cosmological constant that is screened by the self-gravitation between the soft gravitons that inflation rips from the vacuum. Inflation ends with the uni...
2107.02872
Yaghoub Heydarzade
Elham Ghorani and Yaghoub Heydarzade
On the initial singularity in Kantowski-Sachs spacetime
21 pages, 4 figures, published version
Eur. Phys. J. C 81, 557 (2021)
10.1140/epjc/s10052-021-09355-7
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
The emergent universe scenario is a proposal for resolving the Big Bang singularity problem in the standard Friedmann-Lemaitre-Robertson-Walker cosmology. In the context of this scenario, the Universe originates from a nonsingular static state. In the present work, considering the realization of the emergent universe...
[ { "created": "Tue, 6 Jul 2021 20:11:50 GMT", "version": "v1" } ]
2021-07-14
[ [ "Ghorani", "Elham", "" ], [ "Heydarzade", "Yaghoub", "" ] ]
The emergent universe scenario is a proposal for resolving the Big Bang singularity problem in the standard Friedmann-Lemaitre-Robertson-Walker cosmology. In the context of this scenario, the Universe originates from a nonsingular static state. In the present work, considering the realization of the emergent universe s...
0811.3582
Joseph Romano
Lee Samuel Finn, Shane L. Larson, Joseph D. Romano
Detecting a Stochastic Gravitational-Wave Background: The Overlap Reduction Function
Removed incorrect references to the Seto and Taruya papers; added explicit expression for the detector transfer function; final published version
Phys.Rev.D79:062003,2009
10.1103/PhysRevD.79.062003
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Detection of a gravitational-wave stochastic background via ground or space-based gravitational-wave detectors requires the cross-correlation of the response of two or more independent detectors. The cross-correlation involves a frequency-dependent factor -- the so-called overlap reduction function or Hellings-Downs ...
[ { "created": "Fri, 21 Nov 2008 17:03:03 GMT", "version": "v1" }, { "created": "Thu, 30 Apr 2009 15:25:51 GMT", "version": "v2" } ]
2009-11-06
[ [ "Finn", "Lee Samuel", "" ], [ "Larson", "Shane L.", "" ], [ "Romano", "Joseph D.", "" ] ]
Detection of a gravitational-wave stochastic background via ground or space-based gravitational-wave detectors requires the cross-correlation of the response of two or more independent detectors. The cross-correlation involves a frequency-dependent factor -- the so-called overlap reduction function or Hellings-Downs cu...
2111.01283
Andrea Geralico
Donato Bini, Andrea Geralico, Robert T. Jantzen
Petrov type I spacetime curvature: principal null vector spanning dimension
v1: 16 pages; v2: 21 pages, references added, discussion expanded; v3: 21 pages, final version matching the published one
International Journal of Geometric Methods in Modern Physics (2023) 2350087
10.1142/S0219887823500871
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The class of Petrov type I curvature tensors is further divided into those for which the span of the set of distinct principal null directions has dimension four (maximally spanning type I) or dimension three (nonmaximally spanning type I). Explicit examples are provided for both vacuum and nonvacuum spacetimes.
[ { "created": "Mon, 1 Nov 2021 22:26:54 GMT", "version": "v1" }, { "created": "Tue, 15 Mar 2022 22:04:26 GMT", "version": "v2" }, { "created": "Tue, 7 Feb 2023 10:06:49 GMT", "version": "v3" } ]
2023-02-08
[ [ "Bini", "Donato", "" ], [ "Geralico", "Andrea", "" ], [ "Jantzen", "Robert T.", "" ] ]
The class of Petrov type I curvature tensors is further divided into those for which the span of the set of distinct principal null directions has dimension four (maximally spanning type I) or dimension three (nonmaximally spanning type I). Explicit examples are provided for both vacuum and nonvacuum spacetimes.
2312.13659
Jia-Hui Huang
Jia-Hui Huang
No black hole bomb for $D$-dimensional non-extremal Reissner-Nordstrom black holes against charged massive scalar perturbation
34 pages,no figure. arXiv admin note: text overlap with arXiv:2201.00725
null
null
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
The superradiant stability of asymptotically flat $D$-dimensional non-extremal Reissner-Nordstrom black holes under charged massive scalar perturbation is analytically studied. In previous works, it proved that there are no black hole bombs for five and six-dimensional non-extremal Reissner-Nordstrom black holes agai...
[ { "created": "Thu, 21 Dec 2023 08:31:57 GMT", "version": "v1" } ]
2023-12-22
[ [ "Huang", "Jia-Hui", "" ] ]
The superradiant stability of asymptotically flat $D$-dimensional non-extremal Reissner-Nordstrom black holes under charged massive scalar perturbation is analytically studied. In previous works, it proved that there are no black hole bombs for five and six-dimensional non-extremal Reissner-Nordstrom black holes agains...
gr-qc/0604063
Timothy Clifton
John D. Barrow and T. Clifton
Cosmologies with Energy Exchange
12 pages, 1 figure
Phys.Rev.D73:103520,2006
10.1103/PhysRevD.73.103520
null
gr-qc astro-ph
null
We provide a simple mathematical description of the exchange of energy between two fluids in an expanding Friedmann universe with zero spatial curvature. The evolution can be reduced to a single non-linear differential equation which we solve in physically relevant cases and provide an analysis of all the possible ev...
[ { "created": "Mon, 17 Apr 2006 13:32:55 GMT", "version": "v1" }, { "created": "Thu, 25 May 2006 17:14:32 GMT", "version": "v2" } ]
2008-11-26
[ [ "Barrow", "John D.", "" ], [ "Clifton", "T.", "" ] ]
We provide a simple mathematical description of the exchange of energy between two fluids in an expanding Friedmann universe with zero spatial curvature. The evolution can be reduced to a single non-linear differential equation which we solve in physically relevant cases and provide an analysis of all the possible evol...
1909.12344
Mahdi Kord Zangeneh
S. Rajaee Chaloshtary, M. Kord Zangeneh, S. Hajkhalili, A. Sheykhi, S. M. Zebarjad
Thermodynamics and reentrant phase transition for logarithmic nonlinear charged black holes in massive gravity
14 pages (one column), 12 captioned figures
2020
10.1142/S0218271820500819
International Journal of Modern Physics, 29, No. 12, 2050081
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We investigate a new class of $(n+1)$-dimensional topological black hole solutions in the context of massive gravity and in the presence of logarithmic nonlinear electrodynamics. Exploring higher dimensional solutions in massive gravity coupled to nonlinear electrodynamics is motivated by holographic hypothesis as we...
[ { "created": "Thu, 26 Sep 2019 19:15:31 GMT", "version": "v1" }, { "created": "Tue, 18 Feb 2020 22:24:58 GMT", "version": "v2" } ]
2023-10-31
[ [ "Chaloshtary", "S. Rajaee", "" ], [ "Zangeneh", "M. Kord", "" ], [ "Hajkhalili", "S.", "" ], [ "Sheykhi", "A.", "" ], [ "Zebarjad", "S. M.", "" ] ]
We investigate a new class of $(n+1)$-dimensional topological black hole solutions in the context of massive gravity and in the presence of logarithmic nonlinear electrodynamics. Exploring higher dimensional solutions in massive gravity coupled to nonlinear electrodynamics is motivated by holographic hypothesis as well...
1806.09845
Ashutosh Tripathi
Ashutosh Tripathi
Testing General Relativity with X-ray Reflection Spectroscopy of a 'Bare' Active Galactic Nucleus
6 pages, 2 figures, conference
null
null
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Einstein's gravity has been extensively tested in the weak field regime, primarily with experiments in the Solar System and observations of binary pulsars, and current data agree well with theoretical predictions. On the other hand, strong gravity is largely unexplored and there are a number of theories beyond Einste...
[ { "created": "Tue, 26 Jun 2018 08:48:42 GMT", "version": "v1" } ]
2018-06-27
[ [ "Tripathi", "Ashutosh", "" ] ]
Einstein's gravity has been extensively tested in the weak field regime, primarily with experiments in the Solar System and observations of binary pulsars, and current data agree well with theoretical predictions. On the other hand, strong gravity is largely unexplored and there are a number of theories beyond Einstein...
1604.02955
Georgios Lukes Gerakopoulos
Georgios Lukes-Gerakopoulos
Comment on "Chaotic orbits for spinning particles in Schwarzschild spacetime"
3 pages, a comment on the article: C. Verhaaren and E. W. Hirschmann, Chaotic orbits for spinning particles in Schwarzschild spacetime, Phys. Rev. D 81, 124034 (2010)
Phys. Rev. D 94, 108501 (2016)
10.1103/PhysRevD.94.108501
null
gr-qc nlin.CD
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The astrophysical relevance of chaos for a test particle with spin moving in Schwarzschild spacetime was the objective of \cite{Verhaaren10}. Even if the results of the study seem to be qualitatively in agreement with similar works, the study presented in \cite{Verhaaren10} suffers both from theoretical and technical...
[ { "created": "Mon, 11 Apr 2016 13:52:30 GMT", "version": "v1" } ]
2016-11-16
[ [ "Lukes-Gerakopoulos", "Georgios", "" ] ]
The astrophysical relevance of chaos for a test particle with spin moving in Schwarzschild spacetime was the objective of \cite{Verhaaren10}. Even if the results of the study seem to be qualitatively in agreement with similar works, the study presented in \cite{Verhaaren10} suffers both from theoretical and technical i...
2103.14674
Maciej Kolanowski
Maciej Kolanowski and Jerzy Lewandowski
Hamiltonian charges in the asymptotically de Sitter spacetimes
18 pages, 1 figure
null
10.1007/JHEP05(2021)063
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We generalize a notion of 'conserved' charges given by Wald and Zoupas to the asymptotically de Sitter spacetimes. Surprisingly, our construction is less ambiguous than the one encountered in the asymptotically flat context. An expansion around exact solutions possessing Killing vectors provides their physical meanin...
[ { "created": "Fri, 26 Mar 2021 18:23:12 GMT", "version": "v1" } ]
2021-05-26
[ [ "Kolanowski", "Maciej", "" ], [ "Lewandowski", "Jerzy", "" ] ]
We generalize a notion of 'conserved' charges given by Wald and Zoupas to the asymptotically de Sitter spacetimes. Surprisingly, our construction is less ambiguous than the one encountered in the asymptotically flat context. An expansion around exact solutions possessing Killing vectors provides their physical meaning....
2304.09332
Jaroslaw Jaracz
Jaroslaw S. Jaracz
Nonexistence of Solutions to the Coupled Generalized Jang Equation/Zero Divergence System
null
null
10.13140/RG.2.2.20090.77768
null
gr-qc math-ph math.MP
http://creativecommons.org/licenses/by-nc-sa/4.0/
In [5], Bray and Khuri proposed coupling the generalized Jang equation to several different auxiliary equations. The solutions to these coupled systems would then imply the Penrose inequality. One of these involves coupling the generalized Jang equation to $\overline{div}(\phi q)=0$, as this would guarantee the non-n...
[ { "created": "Tue, 18 Apr 2023 22:39:33 GMT", "version": "v1" } ]
2023-04-20
[ [ "Jaracz", "Jaroslaw S.", "" ] ]
In [5], Bray and Khuri proposed coupling the generalized Jang equation to several different auxiliary equations. The solutions to these coupled systems would then imply the Penrose inequality. One of these involves coupling the generalized Jang equation to $\overline{div}(\phi q)=0$, as this would guarantee the non-neg...
1207.5060
Paolo Aschieri
Paolo Aschieri
Extended gravity from noncommutativity
13 pages. Proceedings of the "Twelfth international Symposium Frontiers of fundamental Physics FFP12", Udine 21-23.11.11
null
null
null
gr-qc hep-th math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We review the first order theory of gravity (vierbein formulation) on noncommutative spacetime studied in [1, 2]. The first order formalism allows to couple the theory to fermions. This NC action is then reinterpreted (using the Seiberg-Witten map) as a gravity theory on commutative spacetime that contains terms with...
[ { "created": "Fri, 20 Jul 2012 21:10:31 GMT", "version": "v1" } ]
2012-07-24
[ [ "Aschieri", "Paolo", "" ] ]
We review the first order theory of gravity (vierbein formulation) on noncommutative spacetime studied in [1, 2]. The first order formalism allows to couple the theory to fermions. This NC action is then reinterpreted (using the Seiberg-Witten map) as a gravity theory on commutative spacetime that contains terms with h...
1705.07102
Nirmalya Kajuri
Nirmalya Kajuri
The time measurement problem in quantum cosmology
5 pages. Received Honorable Mention in the 2017 Gravity Research Foundation essay competition
Int. J. Mod. Phys. D, 26, 1743011 (2017)
null
null
gr-qc hep-th quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the canonical approach to quantization of gravity, one often uses relational clock variables and an interpretation in terms of conditional probabilities to overcome the problem of time. In this essay we show that these suffer from serious conceptual issues.
[ { "created": "Fri, 19 May 2017 17:27:26 GMT", "version": "v1" } ]
2017-11-23
[ [ "Kajuri", "Nirmalya", "" ] ]
In the canonical approach to quantization of gravity, one often uses relational clock variables and an interpretation in terms of conditional probabilities to overcome the problem of time. In this essay we show that these suffer from serious conceptual issues.
2012.02343
Jianbo Lu
Jianbo Lu, Jiachun Li, Hui Guo, Zhitong Zhuang, Xin Zhao
Linearized physics and gravitational-waves polarizations in the Palatini formalism of GBD theory
12 pages, no figure
Physics Letters B 811 (2020) 135985
10.1016/j.physletb.2020.135985
null
gr-qc astro-ph.HE
http://creativecommons.org/licenses/by/4.0/
A generalized Brans-Dicke (GBD) theory in the framework of Palatini formalism are proposed in this paper. We derive the field equations by using the variational approach and obtain the linearized equations by using the weak-field approximation method. We show various properties of the geometrical scalar field in the ...
[ { "created": "Fri, 4 Dec 2020 00:28:51 GMT", "version": "v1" } ]
2020-12-30
[ [ "Lu", "Jianbo", "" ], [ "Li", "Jiachun", "" ], [ "Guo", "Hui", "" ], [ "Zhuang", "Zhitong", "" ], [ "Zhao", "Xin", "" ] ]
A generalized Brans-Dicke (GBD) theory in the framework of Palatini formalism are proposed in this paper. We derive the field equations by using the variational approach and obtain the linearized equations by using the weak-field approximation method. We show various properties of the geometrical scalar field in the Pa...
2302.06864
Yorgo Senikoglu
Yorgo Senikoglu
Scattering of complex gravitino test fields from a gravitational pulse
Accepted Version to appear in GERG
null
10.1007/s10714-023-03089-5
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Gravitational pulse waves are defined as step functions at the boundaries. In this setting, linearized Rarita-Schwinger equations are precisely solved in Rosen coordinates. It is found that the gravitino's energy-momentum varies with the sandwich wave's shape. The gravitino's energy density will decrease as it crosse...
[ { "created": "Tue, 14 Feb 2023 07:04:15 GMT", "version": "v1" } ]
2023-03-15
[ [ "Senikoglu", "Yorgo", "" ] ]
Gravitational pulse waves are defined as step functions at the boundaries. In this setting, linearized Rarita-Schwinger equations are precisely solved in Rosen coordinates. It is found that the gravitino's energy-momentum varies with the sandwich wave's shape. The gravitino's energy density will decrease as it crosses ...
1108.2916
Hengzhong Fang
H. Z. Fang and K. H. Zhou
Phonon tunnels across a sonic horizon
null
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider phonon tunneling in sonic black hole by WKB approximation method without the backreaction, in which the relativistic momentum-energy equation is used. We also study the WKB loop (closed path) integral [B. D. Chowdhury, Pramana70:3-26, 2008] in sonic black hole case and discuss the equivalence of the resul...
[ { "created": "Mon, 15 Aug 2011 01:51:20 GMT", "version": "v1" } ]
2011-08-16
[ [ "Fang", "H. Z.", "" ], [ "Zhou", "K. H.", "" ] ]
We consider phonon tunneling in sonic black hole by WKB approximation method without the backreaction, in which the relativistic momentum-energy equation is used. We also study the WKB loop (closed path) integral [B. D. Chowdhury, Pramana70:3-26, 2008] in sonic black hole case and discuss the equivalence of the results...
2209.02278
Tianhao Wu
Tianhao Wu
AdS Wormholes from AdS/Ricci-flat Correspondence
Corrected some typos in the Appendix in previous version
null
10.1103/PhysRevD.108.044001
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We discuss the Wormholes in general dimensions by studying the Einstein-phantom scalar field with and without the cosmological constant. Solving AdS wormholes in general dimension is hard due to the nonlinear nature of the theory. In this work, we implement the AdS/Ricci-flat correspondence, extended to include the a...
[ { "created": "Tue, 6 Sep 2022 08:10:19 GMT", "version": "v1" }, { "created": "Mon, 10 Apr 2023 22:36:18 GMT", "version": "v2" } ]
2023-08-16
[ [ "Wu", "Tianhao", "" ] ]
We discuss the Wormholes in general dimensions by studying the Einstein-phantom scalar field with and without the cosmological constant. Solving AdS wormholes in general dimension is hard due to the nonlinear nature of the theory. In this work, we implement the AdS/Ricci-flat correspondence, extended to include the axi...
2104.09626
Hermann Nicolai
Hermann Nicolai
Complexity and the Big Bang
Revised version: minor additions and clarifications; references added
null
10.1088/1361-6382/ac1b07
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
After a brief review of current scenarios for the resolution and/or avoidance of the Big Bang, an alternative hypothesis is put forward implying an infinite increase in complexity towards the initial singularity. This may result in an effective non-calculability which would present an obstruction to actually reaching...
[ { "created": "Fri, 16 Apr 2021 08:26:53 GMT", "version": "v1" }, { "created": "Wed, 19 May 2021 11:13:45 GMT", "version": "v2" }, { "created": "Thu, 5 Aug 2021 09:52:31 GMT", "version": "v3" } ]
2021-09-22
[ [ "Nicolai", "Hermann", "" ] ]
After a brief review of current scenarios for the resolution and/or avoidance of the Big Bang, an alternative hypothesis is put forward implying an infinite increase in complexity towards the initial singularity. This may result in an effective non-calculability which would present an obstruction to actually reaching t...
2310.11990
Vania Vellucci
Edgardo Franzin, Stefano Liberati, Vania Vellucci
From regular black holes to horizonless objects: quasi-normal modes, instabilities and spectroscopy
null
JCAP01(2024)020
10.1088/1475-7516/2024/01/020
null
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study gravitational and test-field perturbations for the two possible families of spherically symmetric black-hole mimickers that smoothly interpolate between regular black holes and horizonless compact objects accordingly to the value of a regularization parameter. One family can be described by the Bardeen-like ...
[ { "created": "Wed, 18 Oct 2023 14:21:03 GMT", "version": "v1" }, { "created": "Fri, 12 Jan 2024 11:51:57 GMT", "version": "v2" } ]
2024-03-08
[ [ "Franzin", "Edgardo", "" ], [ "Liberati", "Stefano", "" ], [ "Vellucci", "Vania", "" ] ]
We study gravitational and test-field perturbations for the two possible families of spherically symmetric black-hole mimickers that smoothly interpolate between regular black holes and horizonless compact objects accordingly to the value of a regularization parameter. One family can be described by the Bardeen-like me...
1409.1894
Olga Kichakova
Olga Kichakova, Jutta Kunz, Eugen Radu, Yasha Shnir
Non-Abelian fields in AdS$_4$ spacetime: axially symmetric, composite configurations
30 pages, 15 figures
Phys. Rev. D 90, 124012 (2014)
10.1103/PhysRevD.90.124012
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We construct new finite energy regular solutions in Einstein-Yang-Mills-SU(2) theory. They are static, axially symmetric and approach at infinity the anti-de Sitter spacetime background. These configurations are characterized by a pair of integers $(m, n)$, where $m$ is related to the polar angle and $n$ to the azimu...
[ { "created": "Fri, 5 Sep 2014 18:11:13 GMT", "version": "v1" } ]
2014-12-17
[ [ "Kichakova", "Olga", "" ], [ "Kunz", "Jutta", "" ], [ "Radu", "Eugen", "" ], [ "Shnir", "Yasha", "" ] ]
We construct new finite energy regular solutions in Einstein-Yang-Mills-SU(2) theory. They are static, axially symmetric and approach at infinity the anti-de Sitter spacetime background. These configurations are characterized by a pair of integers $(m, n)$, where $m$ is related to the polar angle and $n$ to the azimuth...
1810.03942
Rafael Nunes
Rafael C. Nunes, Supriya Pan, and Emmanuel N. Saridakis
New observational constraints on $f(T)$ gravity through gravitational-wave astronomy
8 pages, 5 figures, 1 table. Matches the version published in PRD
Phys. Rev. D 98, 104055 (2018)
10.1103/PhysRevD.98.104055
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We investigate the new observational constraints on $f(T)$ gravity that arise from the effects of primordial gravitational waves (GWs) on the cosmic microwave background (CMB) anisotropies and the BB spectrum. We first show that on the GWs propagation in $f(T)$ gravity we obtain only an amplitude modification and not...
[ { "created": "Tue, 9 Oct 2018 12:40:04 GMT", "version": "v1" }, { "created": "Thu, 29 Nov 2018 11:06:59 GMT", "version": "v2" } ]
2018-11-30
[ [ "Nunes", "Rafael C.", "" ], [ "Pan", "Supriya", "" ], [ "Saridakis", "Emmanuel N.", "" ] ]
We investigate the new observational constraints on $f(T)$ gravity that arise from the effects of primordial gravitational waves (GWs) on the cosmic microwave background (CMB) anisotropies and the BB spectrum. We first show that on the GWs propagation in $f(T)$ gravity we obtain only an amplitude modification and not a...
1501.04134
Anzhong Wang
Miao Tian, Xinwen Wang, M.F. da Silva, Anzhong Wang
Gravitational collapse and formation of universal horizons
revtex4, 4 figures. Typos are corrected, and new references are added
null
null
null
gr-qc astro-ph.HE hep-ph hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we first generalize the definition of stationary universal horizons to dynamical ones, and then show that (dynamical) universal horizons can be formed from realistic gravitational collapse. This is done by constructing analytical models of a collapsing spherically symmetric star with finite thickness i...
[ { "created": "Fri, 16 Jan 2015 23:32:38 GMT", "version": "v1" }, { "created": "Sat, 24 Jan 2015 17:24:00 GMT", "version": "v2" } ]
2015-01-27
[ [ "Tian", "Miao", "" ], [ "Wang", "Xinwen", "" ], [ "da Silva", "M. F.", "" ], [ "Wang", "Anzhong", "" ] ]
In this paper, we first generalize the definition of stationary universal horizons to dynamical ones, and then show that (dynamical) universal horizons can be formed from realistic gravitational collapse. This is done by constructing analytical models of a collapsing spherically symmetric star with finite thickness in ...
gr-qc/0501018
Sanjeev S. Seahra
Sanjeev S. Seahra
Naked shell singularities on the brane
REVTeX4, 13 pages, 6 figures, references and comments added
Phys.Rev. D71 (2005) 084020
10.1103/PhysRevD.71.084020
null
gr-qc hep-th
null
By utilizing non-standard slicings of 5-dimensional Schwarzschild and Schwarzschild-AdS manifolds based on isotropic coordinates, we generate static and spherically symmetric braneworld spacetimes containing shell-like naked null singularities. For planar slicings, we find that the brane-matter sourcing the solution ...
[ { "created": "Fri, 7 Jan 2005 15:58:48 GMT", "version": "v1" }, { "created": "Thu, 27 Jan 2005 12:42:59 GMT", "version": "v2" } ]
2009-11-11
[ [ "Seahra", "Sanjeev S.", "" ] ]
By utilizing non-standard slicings of 5-dimensional Schwarzschild and Schwarzschild-AdS manifolds based on isotropic coordinates, we generate static and spherically symmetric braneworld spacetimes containing shell-like naked null singularities. For planar slicings, we find that the brane-matter sourcing the solution is...
2308.11695
Dr. Sudhaker Upadhyay
Jyotish Kumar, Sudhaker Upadhyay and Himanshu Kumar Sudhanshu
Small Black String Thermodynamics
12 pages, 6 captioned figures, published in Physica Scripta
Phys. Scr. 98 (2023) 095306
10.1088/1402-4896/aceec3
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
We consider a cylindrically symmetric solution for the field equations of Einstein-Hilbert action with a negative cosmological constant in four dimensions. The small statistical fluctuation in the equilibrium thermodynamics of the black string solution is investigated. The small black string under the influence of sm...
[ { "created": "Tue, 22 Aug 2023 17:27:11 GMT", "version": "v1" } ]
2023-08-24
[ [ "Kumar", "Jyotish", "" ], [ "Upadhyay", "Sudhaker", "" ], [ "Sudhanshu", "Himanshu Kumar", "" ] ]
We consider a cylindrically symmetric solution for the field equations of Einstein-Hilbert action with a negative cosmological constant in four dimensions. The small statistical fluctuation in the equilibrium thermodynamics of the black string solution is investigated. The small black string under the influence of smal...
1912.11227
Chol Jun Kim
Kim Jik-su, Kim Chol-jun
A Special Class of the Scalar-Tensor Gravity with Scalar-Matter Direct Coupling
null
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A role of the scalar-matter direct coupling in the evolution of scalar-tensor gravity was studied. If the coupling functions in the generalized scalar-tensor gravity satisfy a definite equation the scalar-tensor gravity is reduced to Einstein's tensor gravity. We consider the issue in Jordan frame and then Einstein f...
[ { "created": "Tue, 24 Dec 2019 06:55:17 GMT", "version": "v1" } ]
2019-12-25
[ [ "Jik-su", "Kim", "" ], [ "Chol-jun", "Kim", "" ] ]
A role of the scalar-matter direct coupling in the evolution of scalar-tensor gravity was studied. If the coupling functions in the generalized scalar-tensor gravity satisfy a definite equation the scalar-tensor gravity is reduced to Einstein's tensor gravity. We consider the issue in Jordan frame and then Einstein fra...
gr-qc/9507058
Gerald Horwitz
Gerald Horwitz
Time and Entropy from Semi-classical Tunneling of the Cosmological Scale Function
17 pages;, no figure. latex 2e, To appear in Moscow Quantum Gravity Seminar, June 12-19, 1995, latex correction!
Int.J.Mod.Phys.D5:885-902,1996
10.1142/S0218271896000539
ITP-UH-19-95
gr-qc
null
Two major apparently unrelated problems, that of the origin of time in the universe associated with quantum gravity and to the entropy in de Sitter cosmological models, are found to have their origin in a single physical phenomenon: the semi-classical tunneling through a classically forbidden region of the cosmologic...
[ { "created": "Mon, 31 Jul 1995 13:03:11 GMT", "version": "v1" }, { "created": "Mon, 7 Aug 1995 13:41:57 GMT", "version": "v2" } ]
2011-04-15
[ [ "Horwitz", "Gerald", "" ] ]
Two major apparently unrelated problems, that of the origin of time in the universe associated with quantum gravity and to the entropy in de Sitter cosmological models, are found to have their origin in a single physical phenomenon: the semi-classical tunneling through a classically forbidden region of the cosmological...
gr-qc/9811039
Olaf Richter
C. Klein, O. Richter
Riemann-Hilbert Problems for the Ernst Equation and Fibre Bundles
12 pages, to be published in Journal of Geometry and Physics
J.Geom.Phys. 30 (1999) 331-342
10.1016/S0393-0440(98)00067-9
LMU-TPW 98-16
gr-qc
null
Riemann--Hilbert techniques are used in the theory of completely integrable differential equations to generate solutions that contain a free function which can be used at least in principle to solve initial or boundary value problems. The solution of a boundary value problem is thus reduced to the identification of t...
[ { "created": "Thu, 12 Nov 1998 09:46:47 GMT", "version": "v1" } ]
2009-10-31
[ [ "Klein", "C.", "" ], [ "Richter", "O.", "" ] ]
Riemann--Hilbert techniques are used in the theory of completely integrable differential equations to generate solutions that contain a free function which can be used at least in principle to solve initial or boundary value problems. The solution of a boundary value problem is thus reduced to the identification of the...
2108.10706
Andrea Giusti
Andrea Giusti, Stefan Zentarra, Lavinia Heisenberg, Valerio Faraoni
First-order thermodynamics of Horndeski gravity
15 pages, no figures
null
10.1103/PhysRevD.105.124011
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We extend to the Horndeski realm the irreversible thermodynamics description of gravity previously studied in "first generation" scalar-tensor theories. We identify a subclass of Horndeski theories as an out-of--equilibrium state, while general relativity corresponds to an equilibrium state. In this context, we ident...
[ { "created": "Tue, 24 Aug 2021 13:12:17 GMT", "version": "v1" } ]
2022-06-22
[ [ "Giusti", "Andrea", "" ], [ "Zentarra", "Stefan", "" ], [ "Heisenberg", "Lavinia", "" ], [ "Faraoni", "Valerio", "" ] ]
We extend to the Horndeski realm the irreversible thermodynamics description of gravity previously studied in "first generation" scalar-tensor theories. We identify a subclass of Horndeski theories as an out-of--equilibrium state, while general relativity corresponds to an equilibrium state. In this context, we identif...
1006.5150
Nicholas Tsamis
Maria G. Romania (University of Crete), N. C. Tsamis (University of Crete) and R. P. Woodard (University of Florida)
Possible Enhancement of High Frequency Gravitational Waves
27 pages, 11 figures, LaTeX.2e
Class.Quant.Grav.28:075013,2011
10.1088/0264-9381/28/7/075013
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the tensor perturbations in a class of non-local, purely gravitational models which naturally end inflation in a distinctive phase of oscillations with slight and short violations of the weak energy condition. We find the usual generic form for the tensor power spectrum. The presence of the oscillatory phase...
[ { "created": "Sat, 26 Jun 2010 15:52:15 GMT", "version": "v1" }, { "created": "Sat, 5 Mar 2011 21:06:36 GMT", "version": "v2" } ]
2011-03-18
[ [ "Romania", "Maria G.", "", "University of Crete" ], [ "Tsamis", "N. C.", "", "University of\n Crete" ], [ "Woodard", "R. P.", "", "University of Florida" ] ]
We study the tensor perturbations in a class of non-local, purely gravitational models which naturally end inflation in a distinctive phase of oscillations with slight and short violations of the weak energy condition. We find the usual generic form for the tensor power spectrum. The presence of the oscillatory phase l...
gr-qc/9603026
Henk van Elst
Henk van Elst, Claes Uggla
General Relativistic 1+3 Orthonormal Frame Approach Revisited
41 pages, uufiles encoded postscript file, submitted to Phys. Rev. D
Class.Quant.Grav. 14 (1997) 2673-2695
10.1088/0264-9381/14/9/021
QMW-AU-96005
gr-qc
null
The equations of the 1+3 orthonormal frame approach are explicitly presented and discussed. Natural choices of local coordinates are mentioned. A dimensionless formulation is subsequently given. It is demonstrated how one can obtain a number of interesting problems by specializing the general equations. In particular...
[ { "created": "Mon, 18 Mar 1996 15:24:26 GMT", "version": "v1" } ]
2009-10-28
[ [ "van Elst", "Henk", "" ], [ "Uggla", "Claes", "" ] ]
The equations of the 1+3 orthonormal frame approach are explicitly presented and discussed. Natural choices of local coordinates are mentioned. A dimensionless formulation is subsequently given. It is demonstrated how one can obtain a number of interesting problems by specializing the general equations. In particular, ...
2008.09950
Fei Qu
Fei Qu, Si-Jiang Yang, Zhi Wang, Ji-Rong Ren
Weak cosmic censorship conjecture is not violated for a rotating linear dilaton black hole
null
null
null
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we investigate the validity of the weak cosmic censorship conjecture(WCCC) for a rotating linear dilaton black hole from two different methods. By using the classsical ingoing test particle method, we obtain the same results as given in the new version of gedanken experiment recently proposed by Wald. ...
[ { "created": "Sun, 23 Aug 2020 03:21:54 GMT", "version": "v1" }, { "created": "Wed, 21 Apr 2021 16:24:23 GMT", "version": "v2" } ]
2021-04-22
[ [ "Qu", "Fei", "" ], [ "Yang", "Si-Jiang", "" ], [ "Wang", "Zhi", "" ], [ "Ren", "Ji-Rong", "" ] ]
In this paper, we investigate the validity of the weak cosmic censorship conjecture(WCCC) for a rotating linear dilaton black hole from two different methods. By using the classsical ingoing test particle method, we obtain the same results as given in the new version of gedanken experiment recently proposed by Wald. We...
2011.15025
Jiri Kovar
Ji\v{r}\'i Kov\'a\v{r}, Yasufumi Kojima, Petr Slan\'y, Zden\v{e}k Stuchl\'ik, Vladim\'ir Karas
Charged fluids encircling compact objects: force representations and conformal geometries
23 pages, 3 figures
Classical and Quantum Gravity, 37, 245007 (2020)
10.1088/1361-6382/abbe70
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Charged fluids rotating around compact objects can form unique equilibrium structures when ambient large-scale electromagnetic fields combine with strong gravity. Equatorial as well as off-equatorial toroidal structures are among such figures of equilibrium with a direct relevance for astrophysics. To investigate the...
[ { "created": "Mon, 30 Nov 2020 17:28:46 GMT", "version": "v1" } ]
2020-12-30
[ [ "Kovář", "Jiří", "" ], [ "Kojima", "Yasufumi", "" ], [ "Slaný", "Petr", "" ], [ "Stuchlík", "Zdeněk", "" ], [ "Karas", "Vladimír", "" ] ]
Charged fluids rotating around compact objects can form unique equilibrium structures when ambient large-scale electromagnetic fields combine with strong gravity. Equatorial as well as off-equatorial toroidal structures are among such figures of equilibrium with a direct relevance for astrophysics. To investigate their...
2211.15537
Suraj Maurya
Suraj Maurya, Rahul Nigam and Sashideep Gutti
Maximal hypersurface in a D-dimensional dynamical spacetime
16 pages, 14 figures
Phys. Rev. D 109, 044019 (2024)
10.1103/PhysRevD.109.044019
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
In this article, we set up a variational problem to arrive at the equation of the maximal hypersurface in the interior of a spherically symmetric evolving trapped region. In the first part of the article, we present the Lagrangian and the corresponding Euler-Lagrange equations that maximize the interior volume of a t...
[ { "created": "Mon, 28 Nov 2022 16:43:50 GMT", "version": "v1" }, { "created": "Sat, 3 Feb 2024 11:58:47 GMT", "version": "v2" } ]
2024-07-01
[ [ "Maurya", "Suraj", "" ], [ "Nigam", "Rahul", "" ], [ "Gutti", "Sashideep", "" ] ]
In this article, we set up a variational problem to arrive at the equation of the maximal hypersurface in the interior of a spherically symmetric evolving trapped region. In the first part of the article, we present the Lagrangian and the corresponding Euler-Lagrange equations that maximize the interior volume of a tra...
1507.02998
Christopher Moore
Christopher J. Moore, Jonathan R. Gair
Testing the "no-hair" property of black holes with X-ray observations of accretion disks
20 pages, 11 figures, accepted for publication in Physical Review D
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Accretion disks around black holes radiate a significant fraction of the rest mass of the accreting material in the form of thermal radiation from within a few gravitational radii of the black hole ($ r \lesssim 20 G M / c^{2}$). In addition, the accreting matter may also be illuminated by hard X-rays from the surrou...
[ { "created": "Fri, 10 Jul 2015 19:36:48 GMT", "version": "v1" } ]
2015-07-13
[ [ "Moore", "Christopher J.", "" ], [ "Gair", "Jonathan R.", "" ] ]
Accretion disks around black holes radiate a significant fraction of the rest mass of the accreting material in the form of thermal radiation from within a few gravitational radii of the black hole ($ r \lesssim 20 G M / c^{2}$). In addition, the accreting matter may also be illuminated by hard X-rays from the surround...
1009.2783
Marcelo Araujo
M. E. Araujo and W.R. Stoeger
Using Time Drift of Cosmological Redshifts to find the Mass-Energy Density of the Universe
17 pages
Phys.Rev.D82:123513,2010
10.1103/PhysRevD.82.123513
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we show that the mass-energy density of the Universe can be fully determined in terms of the cosmological redshifts, their time drifts and angular-diameter distance (observer area distance). Besides providing an indirect measurement of the mass-energy density of the Universe, we show how one can use the...
[ { "created": "Tue, 14 Sep 2010 20:47:53 GMT", "version": "v1" } ]
2010-12-24
[ [ "Araujo", "M. E.", "" ], [ "Stoeger", "W. R.", "" ] ]
In this paper we show that the mass-energy density of the Universe can be fully determined in terms of the cosmological redshifts, their time drifts and angular-diameter distance (observer area distance). Besides providing an indirect measurement of the mass-energy density of the Universe, we show how one can use the t...
gr-qc/9803094
Andrew Liddle
Diego F Torres, Franz E Schunck and Andrew R Liddle
Brans-Dicke Boson Stars: Configurations and Stability through Cosmic History
9 pages RevTeX file with nine figures incorporated (uses RevTeX and epsf)
Class.Quant.Grav.15:3701-3718,1998
10.1088/0264-9381/15/11/027
SUSSEX-AST 98/3-5
gr-qc
null
We make a detailed study of boson star configurations in Jordan--Brans--Dicke theory, studying both equilibrium properties and stability, and considering boson stars existing at different cosmic epochs. We show that boson stars can be stable at any time of cosmic history and that equilibrium stars are denser in the p...
[ { "created": "Fri, 27 Mar 1998 15:55:18 GMT", "version": "v1" } ]
2011-08-11
[ [ "Torres", "Diego F", "" ], [ "Schunck", "Franz E", "" ], [ "Liddle", "Andrew R", "" ] ]
We make a detailed study of boson star configurations in Jordan--Brans--Dicke theory, studying both equilibrium properties and stability, and considering boson stars existing at different cosmic epochs. We show that boson stars can be stable at any time of cosmic history and that equilibrium stars are denser in the pas...
0812.4489
Hao Wei
Hao Wei
Relaxing the Cosmological Constraints on Unparticle Dark Component
11 pages, 5 figures, revtex4; v2: discussions added, accepted by Eur. Phys. J. C; v3: published version
Eur.Phys.J.C62:579-586,2009
10.1140/epjc/s10052-009-1056-5
null
gr-qc astro-ph hep-ph hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Unparticle physics has been an active field since the seminal work of Georgi. Recently, many constraints on unparticles from various observations have been considered in the literature. In particular, the cosmological constraints on the unparticle dark component put it in a serious situation. In this work, we try to ...
[ { "created": "Wed, 24 Dec 2008 10:10:07 GMT", "version": "v1" }, { "created": "Fri, 15 May 2009 03:24:19 GMT", "version": "v2" }, { "created": "Thu, 30 Jul 2009 07:00:00 GMT", "version": "v3" } ]
2009-07-30
[ [ "Wei", "Hao", "" ] ]
Unparticle physics has been an active field since the seminal work of Georgi. Recently, many constraints on unparticles from various observations have been considered in the literature. In particular, the cosmological constraints on the unparticle dark component put it in a serious situation. In this work, we try to fi...
2012.14291
Vipin Dubey
Umesh Kumar Sharma, Gunjan Varshney, Vipin Chandra Dubey
Barrow agegraphic dark energy
null
null
10.1142/S0218271821500218
null
gr-qc
http://creativecommons.org/publicdomain/zero/1.0/
In this work, we propose a new dark energy model by applying the Barrow entropy and the holographic principle, with a time scale as IR cut off. Analysing the conformal time as well as universe's age as infrared cut-offs, we explore the cosmological importance of the suggested dark energy models and examine the univer...
[ { "created": "Thu, 24 Dec 2020 15:21:34 GMT", "version": "v1" } ]
2020-12-29
[ [ "Sharma", "Umesh Kumar", "" ], [ "Varshney", "Gunjan", "" ], [ "Dubey", "Vipin Chandra", "" ] ]
In this work, we propose a new dark energy model by applying the Barrow entropy and the holographic principle, with a time scale as IR cut off. Analysing the conformal time as well as universe's age as infrared cut-offs, we explore the cosmological importance of the suggested dark energy models and examine the universe...
2312.06615
Bouzenada Abdelmalek .
Faizuddin Ahmed and Abdelmalek Bouzenada
Effects of rainbow gravity on charge-free scalar Bosons in Bonnor-Melvin s universe with cosmological constant
null
null
null
null
gr-qc hep-th
http://creativecommons.org/publicdomain/zero/1.0/
In this paper, we explore the relativistic quantum motion of spin-zero scalar particles influenced by rainbow gravity's in the background of a magnetic solution. Our focus is on the Bonnor-Melvin magnetic space-time, a four-dimensional solution featuring a non-zero cosmological constant. To analyze this scenario, we ...
[ { "created": "Fri, 8 Dec 2023 10:56:32 GMT", "version": "v1" } ]
2023-12-12
[ [ "Ahmed", "Faizuddin", "" ], [ "Bouzenada", "Abdelmalek", "" ] ]
In this paper, we explore the relativistic quantum motion of spin-zero scalar particles influenced by rainbow gravity's in the background of a magnetic solution. Our focus is on the Bonnor-Melvin magnetic space-time, a four-dimensional solution featuring a non-zero cosmological constant. To analyze this scenario, we so...
1508.00732
Sabine Hossenfelder
S. Hossenfelder
A relativistic acoustic metric for planar black holes
11 pages, no figures, replaced with published version
Phys.Lett. B752 (2016) 13-17
10.1016/j.physletb.2015.11.026
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We demonstrate here that the metric of a planar black hole in asymptotic Anti-de Sitter space can, on a slice of dimension 3+1, be reproduced as a relativistic acoustic metric. This completes an earlier calculation in which the non-relativistic limit was used, and also serves to obtain a concrete form of the Lagrangi...
[ { "created": "Tue, 4 Aug 2015 11:11:22 GMT", "version": "v1" }, { "created": "Fri, 7 Aug 2015 14:25:57 GMT", "version": "v2" }, { "created": "Mon, 21 Dec 2015 13:33:17 GMT", "version": "v3" } ]
2015-12-22
[ [ "Hossenfelder", "S.", "" ] ]
We demonstrate here that the metric of a planar black hole in asymptotic Anti-de Sitter space can, on a slice of dimension 3+1, be reproduced as a relativistic acoustic metric. This completes an earlier calculation in which the non-relativistic limit was used, and also serves to obtain a concrete form of the Lagrangian...
1812.00938
Jorge L. Fuentes
Jorge L. Fuentes, Usman A. Gillani and Karim A. Malik
Linear cosmological perturbations in almost scale-invariant fourth-order gravity
13 pages. Companion Mathematica notebooks can be found in https://github.com/jorchfv/Linear-Gauss-Bonnet
null
null
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study a class of almost scale-invariant modified gravity theories, using a particular form of $f(R, G) = \alpha R^2 + \beta G \log G$ where $R$ and $G$ are the Ricci and Gauss-Bonnet scalars, respectively and $\alpha$, $\beta$ are arbitrary constants. We derive the Einstein-like field equations to first order in c...
[ { "created": "Mon, 3 Dec 2018 18:06:06 GMT", "version": "v1" } ]
2018-12-04
[ [ "Fuentes", "Jorge L.", "" ], [ "Gillani", "Usman A.", "" ], [ "Malik", "Karim A.", "" ] ]
We study a class of almost scale-invariant modified gravity theories, using a particular form of $f(R, G) = \alpha R^2 + \beta G \log G$ where $R$ and $G$ are the Ricci and Gauss-Bonnet scalars, respectively and $\alpha$, $\beta$ are arbitrary constants. We derive the Einstein-like field equations to first order in cos...
2301.12464
Julio Cesar Fabris
Marcelo H. Alvarenga, J\'ulio C. Fabris and Hermano Velten
Using cosmological perturbation theory to distinguish between General Relativity and Unimodular Gravity
Latex file, 9 pages. Contribution to the proceedings of the International Conference on Particle Physics and Astrophysics (ICCPA-2022)}
null
null
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Unimodular Gravity is one of the oldest geometric gravity theory alternative to General Relativity. Essentially, it is based on the Einstein-Hilbert Lagrangian with an additional constraint on the determinant of the metric. It can be explicitly shown that Unimodular Gravity can be recast as General Relativity in pres...
[ { "created": "Sun, 29 Jan 2023 15:24:43 GMT", "version": "v1" } ]
2023-01-31
[ [ "Alvarenga", "Marcelo H.", "" ], [ "Fabris", "Júlio C.", "" ], [ "Velten", "Hermano", "" ] ]
Unimodular Gravity is one of the oldest geometric gravity theory alternative to General Relativity. Essentially, it is based on the Einstein-Hilbert Lagrangian with an additional constraint on the determinant of the metric. It can be explicitly shown that Unimodular Gravity can be recast as General Relativity in presen...
gr-qc/9905087
John Baez
John C. Baez
An Introduction to Spin Foam Models of Quantum Gravity and BF Theory
55 pages LaTeX, 31 encapsulated Postscript figures
Lect. Notes Phys. 543 (2000) 25-94
null
null
gr-qc hep-th math.QA
null
In loop quantum gravity we now have a clear picture of the quantum geometry of space, thanks in part to the theory of spin networks. The concept of `spin foam' is intended to serve as a similar picture for the quantum geometry of spacetime. In general, a spin network is a graph with edges labelled by representations ...
[ { "created": "Fri, 21 May 1999 23:25:08 GMT", "version": "v1" } ]
2015-02-13
[ [ "Baez", "John C.", "" ] ]
In loop quantum gravity we now have a clear picture of the quantum geometry of space, thanks in part to the theory of spin networks. The concept of `spin foam' is intended to serve as a similar picture for the quantum geometry of spacetime. In general, a spin network is a graph with edges labelled by representations an...
1809.08557
Thomas-Paul Hack
Klaus Fredenhagen, Thomas-Paul Hack, Nicola Pinamonti
Thermodynamics of Quantum Fields in Nonstationary Spacetimes
Contribution to "Particles, String and the Early Universe - Research Results of the Collaborative Research Centre SFB 676 in Hamburg
null
null
null
gr-qc hep-th math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Quantum field theory (QFT) on non-stationary spacetimes is well understood from the side of the algebra of observables. The state space, however, is largely unexplored, due to the non-existence of distinguished states (vacuum, scattering states, thermal states). Project C7 of the SFB 676 was focused on characterisati...
[ { "created": "Sun, 23 Sep 2018 08:58:59 GMT", "version": "v1" } ]
2018-09-25
[ [ "Fredenhagen", "Klaus", "" ], [ "Hack", "Thomas-Paul", "" ], [ "Pinamonti", "Nicola", "" ] ]
Quantum field theory (QFT) on non-stationary spacetimes is well understood from the side of the algebra of observables. The state space, however, is largely unexplored, due to the non-existence of distinguished states (vacuum, scattering states, thermal states). Project C7 of the SFB 676 was focused on characterisation...
1010.5444
Muxin Han
Muxin Han, Thomas Thiemann
Commuting Simplicity and Closure Constraints for 4D Spin Foam Models
41 pages, 4 figures
Class. Quantum Grav. 30 (2013) 235024
10.1088/0264-9381/30/23/235024
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Spin Foam Models are supposed to be discretised path integrals for quantum gravity constructed from the Plebanski-Holst action. The reason for there being several models currently under consideration is that no consensus has been reached for how to implement the simplicity constraints. Indeed, none of these models st...
[ { "created": "Tue, 26 Oct 2010 16:15:51 GMT", "version": "v1" }, { "created": "Thu, 31 Oct 2013 10:02:05 GMT", "version": "v2" } ]
2013-11-01
[ [ "Han", "Muxin", "" ], [ "Thiemann", "Thomas", "" ] ]
Spin Foam Models are supposed to be discretised path integrals for quantum gravity constructed from the Plebanski-Holst action. The reason for there being several models currently under consideration is that no consensus has been reached for how to implement the simplicity constraints. Indeed, none of these models stri...
1910.03666
Elizabeth Winstanley
Visakan Balakumar and Elizabeth Winstanley
Hadamard renormalization for a charged scalar field
31 pages, new section comparing with other approaches to renormalization, minor edits
null
10.1088/1361-6382/ab6b6e
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The Hadamard representation of the Green's function of a quantum field on a curved space-time is a powerful tool for computations of renormalized expectation values. We study the Hadamard form of the Feynman Green's function for a massive charged complex scalar field in an arbitrary number of space-time dimensions. E...
[ { "created": "Tue, 8 Oct 2019 20:17:04 GMT", "version": "v1" }, { "created": "Thu, 23 Jan 2020 18:29:09 GMT", "version": "v2" } ]
2020-04-08
[ [ "Balakumar", "Visakan", "" ], [ "Winstanley", "Elizabeth", "" ] ]
The Hadamard representation of the Green's function of a quantum field on a curved space-time is a powerful tool for computations of renormalized expectation values. We study the Hadamard form of the Feynman Green's function for a massive charged complex scalar field in an arbitrary number of space-time dimensions. Exp...
0806.1018
Jose' P. S. Lemos
Gon\c{c}alo A. S. Dias, Jos\'e P. S. Lemos
Hamiltonian thermodynamics of three-dimensional dilatonic black holes
34 pages, 3 figures, references added, minor changes in the revised version
Phys.Rev.D78:044010,2008
10.1103/PhysRevD.78.044010
null
gr-qc hep-th math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The action for a class of three-dimensional dilaton-gravity theories with a cosmological constant can be recast in a Brans-Dicke type action, with its free $\omega$ parameter. These theories have static spherically symmetric black holes. Those with well formulated asymptotics are studied through a Hamiltonian formali...
[ { "created": "Thu, 5 Jun 2008 17:34:07 GMT", "version": "v1" }, { "created": "Thu, 14 Aug 2008 21:53:18 GMT", "version": "v2" } ]
2008-11-26
[ [ "Dias", "Gonçalo A. S.", "" ], [ "Lemos", "José P. S.", "" ] ]
The action for a class of three-dimensional dilaton-gravity theories with a cosmological constant can be recast in a Brans-Dicke type action, with its free $\omega$ parameter. These theories have static spherically symmetric black holes. Those with well formulated asymptotics are studied through a Hamiltonian formalism...
2009.13334
Xiao Yan Chew
Xiao Yan Chew and Kok-Geng Lim
Non--Abelian Wormholes Threaded by Yang--Mills--Higgs Field in the BPS Limit
11 pages with 15 figures
Phys. Rev. D 102, 124068 (2020)
10.1103/PhysRevD.102.124068
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the Bogomol'nyi-Prasad-Sommerfield (BPS) limit of Einstein-Yang-Mills-Higgs theory, we construct numerically a non-Abelian wormhole supported by a phantom field. The probe limit is the Yang-Mills-Higgs field in the background of Ellis wormhole when the gravity is switched off. The wormhole solutions possess the Ya...
[ { "created": "Mon, 28 Sep 2020 14:00:19 GMT", "version": "v1" }, { "created": "Wed, 30 Sep 2020 02:58:43 GMT", "version": "v2" }, { "created": "Wed, 7 Oct 2020 07:56:06 GMT", "version": "v3" }, { "created": "Mon, 4 Jan 2021 02:10:11 GMT", "version": "v4" } ]
2021-01-06
[ [ "Chew", "Xiao Yan", "" ], [ "Lim", "Kok-Geng", "" ] ]
In the Bogomol'nyi-Prasad-Sommerfield (BPS) limit of Einstein-Yang-Mills-Higgs theory, we construct numerically a non-Abelian wormhole supported by a phantom field. The probe limit is the Yang-Mills-Higgs field in the background of Ellis wormhole when the gravity is switched off. The wormhole solutions possess the Yang...
1610.03805
Wolfgang Tichy
Wolfgang Tichy
The initial value problem as it relates to numerical relativity
64 pages, 5 figures, updated with version published in Reports on Progress in Physics
Reports on Progress in Physics 80, 026901 (2017)
10.1088/1361-6633/80/2/026901
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Spacetime is foliated by spatial hypersurfaces in the 3+1 split of General Relativity. The initial value problem then consists of specifying initial data for all relevant fields on one such a spatial hypersurface. These fields are the 3-metric and extrinsic curvature together with matter fields such as fluid velocity...
[ { "created": "Wed, 12 Oct 2016 17:52:17 GMT", "version": "v1" }, { "created": "Fri, 23 Dec 2016 14:32:04 GMT", "version": "v2" } ]
2017-01-04
[ [ "Tichy", "Wolfgang", "" ] ]
Spacetime is foliated by spatial hypersurfaces in the 3+1 split of General Relativity. The initial value problem then consists of specifying initial data for all relevant fields on one such a spatial hypersurface. These fields are the 3-metric and extrinsic curvature together with matter fields such as fluid velocity, ...
2012.06869
Grigoris Panotopoulos
Grigoris Panotopoulos, Ilidio Lopes and Angel Rincon
Lagrangian formulation for an extended cosmological equation-of-state
6 pages, 3 figures
Phys. Dark Univ. 31 (2021) 100751
10.1016/j.dark.2020.100751
null
gr-qc astro-ph.CO hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We show that the extended cosmological equation-of-state developed starting from a Chaplygin equation-of-state, recently applied to stellar modeling, is a viable dark energy model consistent with standard scalar potentials. Moreover we find a Lagrangian formulation based on a canonical scalar field with the appropria...
[ { "created": "Sat, 12 Dec 2020 17:28:41 GMT", "version": "v1" } ]
2020-12-15
[ [ "Panotopoulos", "Grigoris", "" ], [ "Lopes", "Ilidio", "" ], [ "Rincon", "Angel", "" ] ]
We show that the extended cosmological equation-of-state developed starting from a Chaplygin equation-of-state, recently applied to stellar modeling, is a viable dark energy model consistent with standard scalar potentials. Moreover we find a Lagrangian formulation based on a canonical scalar field with the appropriate...
gr-qc/9408032
Robert Mann
J.S.F. Chan and R.B. Mann
Gravitation and Cosmology in Generalized (1+1)-dimensional dilaton gravity
34 pages
Class.Quant.Grav.12:351-372,1995
10.1088/0264-9381/12/2/006
null
gr-qc
null
The actions of the ``$R=T$'' and string-inspired theories of gravity in (1+1) dimensions are generalized into one single action which is characterized by two functions. We discuss differing interpretations of the matter stress-energy tensor, and show how two such different interpretations can yield two different sets...
[ { "created": "Thu, 25 Aug 1994 20:04:37 GMT", "version": "v1" } ]
2010-04-06
[ [ "Chan", "J. S. F.", "" ], [ "Mann", "R. B.", "" ] ]
The actions of the ``$R=T$'' and string-inspired theories of gravity in (1+1) dimensions are generalized into one single action which is characterized by two functions. We discuss differing interpretations of the matter stress-energy tensor, and show how two such different interpretations can yield two different sets o...
gr-qc/9406035
null
Bjorn Jensen and Jarom\'ir Ku\v{c}era
A reinterpretation of the Taub singularity
11, Oslo-TP-9-94, TP-MUBR 94-06/1
null
10.1016/0375-9601(94)90081-7
null
gr-qc
null
We reinterpret the well known Taub-singularity in terms of a cylinder symmetric geometry. It is shown that a cylindrical analog to the Einstein-Rosen bridge as well as a cosmic string will be present in the geometry.
[ { "created": "Tue, 21 Jun 1994 13:16:57 GMT", "version": "v1" } ]
2016-08-14
[ [ "Jensen", "Bjorn", "" ], [ "Kučera", "Jaromír", "" ] ]
We reinterpret the well known Taub-singularity in terms of a cylinder symmetric geometry. It is shown that a cylindrical analog to the Einstein-Rosen bridge as well as a cosmic string will be present in the geometry.
gr-qc/0607024
Fernando Mendez
R. Aloisio, A. Galante, A.F. Grillo, S. Liberati, E. Luzio and F. Mendez
Modified Special Relativity on a fluctuating spacetime
7 pages, no figures
Phys.Rev. D74 (2006) 085017
10.1103/PhysRevD.74.085017
null
gr-qc
null
It was recently proposed that deformations of the relativistic symmetry, as those considered in Deformed Special Relativity (DSR), can be seen as the outcome of a measurement theory in the presence of non-negligible (albeit small) quantum gravitational fluctuations [1,2]. In this paper we explicitly consider the case...
[ { "created": "Thu, 6 Jul 2006 14:35:36 GMT", "version": "v1" } ]
2009-11-11
[ [ "Aloisio", "R.", "" ], [ "Galante", "A.", "" ], [ "Grillo", "A. F.", "" ], [ "Liberati", "S.", "" ], [ "Luzio", "E.", "" ], [ "Mendez", "F.", "" ] ]
It was recently proposed that deformations of the relativistic symmetry, as those considered in Deformed Special Relativity (DSR), can be seen as the outcome of a measurement theory in the presence of non-negligible (albeit small) quantum gravitational fluctuations [1,2]. In this paper we explicitly consider the case o...
2007.10259
Naveena Kumara A
Kartheek Hegde, A. Naveena Kumara, C.L. Ahmed Rizwan, Md Sabir Ali and Ajith K.M
Null Geodesics and Thermodynamic Phase Transition of Four-Dimensional Gauss-Bonnet AdS Black Hole
18 pages, 5 figures
null
10.1016/j.aop.2021.168461
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Modified gravity theories are of great interest in both observational and theoretical studies. In this article we study the correlation between the null geodesics in the background of a four-dimensional Einstein-Maxwell-Gauss-Bonnet AdS black hole, a modification of Einstein gravity, and it's thermodynamic phase tran...
[ { "created": "Mon, 20 Jul 2020 16:47:02 GMT", "version": "v1" } ]
2021-05-19
[ [ "Hegde", "Kartheek", "" ], [ "Kumara", "A. Naveena", "" ], [ "Rizwan", "C. L. Ahmed", "" ], [ "Ali", "Md Sabir", "" ], [ "M", "Ajith K.", "" ] ]
Modified gravity theories are of great interest in both observational and theoretical studies. In this article we study the correlation between the null geodesics in the background of a four-dimensional Einstein-Maxwell-Gauss-Bonnet AdS black hole, a modification of Einstein gravity, and it's thermodynamic phase transi...
1202.2285
Hristu Culetu
Hristu Culetu
Conformal time dependent Painleve-Gullstrand spacetime
8 pages, no figures, one chapter added, new refs
null
null
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The properties of an anisotropic fluid outside a star or a black hole embedded in an expanding universe are investigated. One finds that, in Painleve-Gullstrand coordinates, the heat flux of the cosmological fluid vanishes, in spite of the nonzero value of a non-diagonal component of the stress tensor. The pressures ...
[ { "created": "Fri, 10 Feb 2012 15:42:30 GMT", "version": "v1" }, { "created": "Tue, 20 Mar 2012 15:06:24 GMT", "version": "v2" } ]
2012-03-21
[ [ "Culetu", "Hristu", "" ] ]
The properties of an anisotropic fluid outside a star or a black hole embedded in an expanding universe are investigated. One finds that, in Painleve-Gullstrand coordinates, the heat flux of the cosmological fluid vanishes, in spite of the nonzero value of a non-diagonal component of the stress tensor. The pressures an...
1905.01427
Tuan Do
Tuan Q. Do, Sonnet Hung Q. Nguyen
No small hairs in anisotropic power-law Gauss-Bonnet inflation
15 pages, two figures. To be published in Communications in Physics, a leading physical journal in Vietnam
Communications in Physics 29, 173 (2019)
10.15625/0868-3166/29/2/13677
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We will examine whether anisotropic hairs exist in a string-inspired scalar-Gauss-Bonnet gravity model with the absence of potential of scalar field during the inflationary phase. As a result, we are able to obtain the Bianchi type I power-law solution to this model under the assumption that the scalar field acts as ...
[ { "created": "Sat, 4 May 2019 04:18:42 GMT", "version": "v1" } ]
2019-05-16
[ [ "Do", "Tuan Q.", "" ], [ "Nguyen", "Sonnet Hung Q.", "" ] ]
We will examine whether anisotropic hairs exist in a string-inspired scalar-Gauss-Bonnet gravity model with the absence of potential of scalar field during the inflationary phase. As a result, we are able to obtain the Bianchi type I power-law solution to this model under the assumption that the scalar field acts as th...
1405.4229
Sunandan Gangopadhyay
Sunandan Gangopadhyay
Minimal length effects in black hole thermodynamics from tunneling formalism
9 pages Latex, To appear in Int.J.Theo.Phys
Int J Theor Phys 55 (2016) 617
10.1007/s10773-015-2699-7
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The tunneling formalism in the Hamilton-Jacobi approach is adopted to study Hawking radiation of massless Dirac particles from spherically symmetric black hole spacetimes incorporating the effects of the generalized uncertainty principle. The Hawking temperature is found to contain corrections from the generalized un...
[ { "created": "Fri, 16 May 2014 16:19:40 GMT", "version": "v1" }, { "created": "Wed, 16 Jul 2014 10:25:06 GMT", "version": "v2" }, { "created": "Thu, 28 May 2015 14:16:15 GMT", "version": "v3" } ]
2016-01-05
[ [ "Gangopadhyay", "Sunandan", "" ] ]
The tunneling formalism in the Hamilton-Jacobi approach is adopted to study Hawking radiation of massless Dirac particles from spherically symmetric black hole spacetimes incorporating the effects of the generalized uncertainty principle. The Hawking temperature is found to contain corrections from the generalized unce...
1908.11647
Sumati Surya
William J. Cunningham and Sumati Surya
Dimensionally Restricted Causal Set Quantum Gravity: Examples in Two and Three Dimensions
31 pages, 21 figures. Typos corrected, figures corrected, references updated
null
10.1088/1361-6382/ab60b7
null
gr-qc hep-lat
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study dimensionally restricted non-perturbative causal set quantum dynamics in $2$ and $3$ spacetime dimensions with non-trivial global spatial topology. The causal set sample space is generated from causal embeddings into spacetime lattices with global spatial topology $S^1$ and $T^2$ in $2$ and $3$ dimensi...
[ { "created": "Fri, 30 Aug 2019 10:51:22 GMT", "version": "v1" }, { "created": "Tue, 3 Dec 2019 07:26:12 GMT", "version": "v2" } ]
2020-04-08
[ [ "Cunningham", "William J.", "" ], [ "Surya", "Sumati", "" ] ]
We study dimensionally restricted non-perturbative causal set quantum dynamics in $2$ and $3$ spacetime dimensions with non-trivial global spatial topology. The causal set sample space is generated from causal embeddings into spacetime lattices with global spatial topology $S^1$ and $T^2$ in $2$ and $3$ dimensions, res...
1810.08780
Handhika Ramadhan
Byon N. Jayawiguna and Handhika S. Ramadhan
Charged black holes in higher-dimensional Eddington-inspired Born-Infeld gravity
36 pages, 16 figures, accepted for publication in Nucl. Phys. B
null
10.1016/j.nuclphysb.2019.114615
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study static (electrically)-charged solutions of Eddington-inspired Born-Infeld (EiBI) theory of gravity in general $D$-dimensional spacetime. We consider both linear (Maxwell) as well as nonlinear electrodynamics for the matter fields. In this particular work, the nonlinear theory we specifically consider is the ...
[ { "created": "Sat, 20 Oct 2018 09:53:11 GMT", "version": "v1" }, { "created": "Wed, 24 Oct 2018 14:31:19 GMT", "version": "v2" }, { "created": "Tue, 6 Nov 2018 02:55:36 GMT", "version": "v3" }, { "created": "Fri, 5 Apr 2019 03:02:15 GMT", "version": "v4" } ]
2019-06-26
[ [ "Jayawiguna", "Byon N.", "" ], [ "Ramadhan", "Handhika S.", "" ] ]
We study static (electrically)-charged solutions of Eddington-inspired Born-Infeld (EiBI) theory of gravity in general $D$-dimensional spacetime. We consider both linear (Maxwell) as well as nonlinear electrodynamics for the matter fields. In this particular work, the nonlinear theory we specifically consider is the Bo...
2101.07265
Kaloian Lozanov
Peter Adshead and Kaloian D. Lozanov
Self-gravitating Vector Dark Matter
15 pages (9+6), 5 figures; matches published version
Phys. Rev. D 103, 103501 (2021)
10.1103/PhysRevD.103.103501
null
gr-qc astro-ph.CO hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We derive the non-relativistic limit of a massive vector field. We show that the Cartesian spatial components of the vector behave as three identical, non-interacting scalar fields. We find classes of spherical, cylindrical, and planar self-gravitating vector solitons in the Newtonian limit. The gravitational propert...
[ { "created": "Mon, 18 Jan 2021 19:00:01 GMT", "version": "v1" }, { "created": "Wed, 7 Jul 2021 19:26:41 GMT", "version": "v2" } ]
2021-07-09
[ [ "Adshead", "Peter", "" ], [ "Lozanov", "Kaloian D.", "" ] ]
We derive the non-relativistic limit of a massive vector field. We show that the Cartesian spatial components of the vector behave as three identical, non-interacting scalar fields. We find classes of spherical, cylindrical, and planar self-gravitating vector solitons in the Newtonian limit. The gravitational propertie...
1304.4844
J. W. van Holten
J.W. van Holten
Single scalar cosmology
9 pages, 7 figures v2: typo corrected; reference added; discussion section added
Int. J. Mod. Phys. A 28 (2013), 1350132
10.1142/S0217751X13501327
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The cosmology of flat FLRW universes dominated by a single scalar field is discussed. General features of the evolution of the universe and the scalar field are illustrated by specific examples. In particular the role of critical points, where the scalar field is stationary, is emphasized and their classification and...
[ { "created": "Wed, 17 Apr 2013 14:55:12 GMT", "version": "v1" }, { "created": "Fri, 27 Sep 2013 07:46:31 GMT", "version": "v2" } ]
2015-11-24
[ [ "van Holten", "J. W.", "" ] ]
The cosmology of flat FLRW universes dominated by a single scalar field is discussed. General features of the evolution of the universe and the scalar field are illustrated by specific examples. In particular the role of critical points, where the scalar field is stationary, is emphasized and their classification and i...
1306.6541
Ali Kaya
Ali Kaya
In-in formalism, pseudo-instantons and rethinking quantum cosmology
9 pages, Essay written for the Gravity Research Foundation 2013 Awards for Essays on Gravitation, received honorable mention
null
10.1142/S0218271814500266
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Unlike flat space quantum field theories that focus on scattering amplitudes, the main observables in quantum cosmology are correlation functions. The systematic way of calculating correlators is called in-in formalism, which requires only a single asymptotic region, i.e. past infinity. The rules in perturbation theo...
[ { "created": "Thu, 27 Jun 2013 15:13:03 GMT", "version": "v1" } ]
2015-06-16
[ [ "Kaya", "Ali", "" ] ]
Unlike flat space quantum field theories that focus on scattering amplitudes, the main observables in quantum cosmology are correlation functions. The systematic way of calculating correlators is called in-in formalism, which requires only a single asymptotic region, i.e. past infinity. The rules in perturbation theory...
2203.02685
Yaoguang Zheng
Wen-Xiang Chen, Yao-Guang Zheng
Thermodynamic geometric analysis of BTZ black hole in f(R,{\phi}) Gravity
arXiv admin note: substantial text overlap with arXiv:2112.15032
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this work, we obtain the thermodynamic geometry of the extended black hole solution under f(R) gravity. This is the foundation of our work. We also obtain the exact form of the f(R) model for some solutions. In the thermodynamic analysis, we calculate the thermodynamic quantities such as temperature and entropy of...
[ { "created": "Sat, 5 Mar 2022 08:54:26 GMT", "version": "v1" }, { "created": "Thu, 24 Mar 2022 10:58:28 GMT", "version": "v2" }, { "created": "Fri, 25 Mar 2022 01:52:16 GMT", "version": "v3" } ]
2022-03-28
[ [ "Chen", "Wen-Xiang", "" ], [ "Zheng", "Yao-Guang", "" ] ]
In this work, we obtain the thermodynamic geometry of the extended black hole solution under f(R) gravity. This is the foundation of our work. We also obtain the exact form of the f(R) model for some solutions. In the thermodynamic analysis, we calculate the thermodynamic quantities such as temperature and entropy of t...
gr-qc/0204010
Alberto Guijosa
Ulf H. Danielsson, Alberto Guijosa, Martin Kruczenski
Black Brane Entropy from Brane-Antibrane Systems
6 pages, revtex; aimed at non-string-theorists. Invited talk at the IV Mexican Workshop on Gravitation and Mathematical Physics, Chapala, Mexico, November 2001
Rev.Mex.Fis.49S2:61-66,2003
null
ICN-UNAM-02/03
gr-qc hep-th
null
In the context of string theory, it is possible to explain the microscopic origin of the entropy of certain black holes in terms of D-brane systems. To date, most of the cases studied in detail refer to extremal (supersymmetric) or near-extremal black holes. In this work we propose a microscopic model for certain bla...
[ { "created": "Tue, 2 Apr 2002 21:01:48 GMT", "version": "v1" } ]
2014-11-17
[ [ "Danielsson", "Ulf H.", "" ], [ "Guijosa", "Alberto", "" ], [ "Kruczenski", "Martin", "" ] ]
In the context of string theory, it is possible to explain the microscopic origin of the entropy of certain black holes in terms of D-brane systems. To date, most of the cases studied in detail refer to extremal (supersymmetric) or near-extremal black holes. In this work we propose a microscopic model for certain black...
1310.1165
Barun Majumder
Barun Majumder
The Effects of Minimal Length in Entropic Force Approach
12 pages, to appear in Advances in High Energy Physics
Advances in High Energy Physics Volume 2013 (2013), Article ID 296836, 8 pages
10.1155/2013/296836
null
gr-qc astro-ph.CO hep-th physics.class-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
With Verlinde's recent proposal which says that gravity can be identified with an entropic force and considering the effects of generalized uncertainty principle in the black hole entropy-area relation we derive the modified equations for Newton's law of gravitation, modified Newtonian dynamics and Einstein's general...
[ { "created": "Fri, 4 Oct 2013 04:42:10 GMT", "version": "v1" } ]
2013-11-11
[ [ "Majumder", "Barun", "" ] ]
With Verlinde's recent proposal which says that gravity can be identified with an entropic force and considering the effects of generalized uncertainty principle in the black hole entropy-area relation we derive the modified equations for Newton's law of gravitation, modified Newtonian dynamics and Einstein's general r...
2107.13952
Francesco Gozzini
Francesco Gozzini
A high-performance code for EPRL spin foam amplitudes
26 pages, many figures and code snippets
null
10.1088/1361-6382/ac2b0b
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
We present $\mathtt{\text{sl2cfoam-next}}$, a high-performance software library for computing Lorentzian EPRL spin foam amplitudes. The library improves on previous codes by many orders of magnitude in single-core performance, can be parallelized on a large number of CPUs and on the GPU, and can be used interactively...
[ { "created": "Thu, 29 Jul 2021 13:20:46 GMT", "version": "v1" } ]
2021-11-17
[ [ "Gozzini", "Francesco", "" ] ]
We present $\mathtt{\text{sl2cfoam-next}}$, a high-performance software library for computing Lorentzian EPRL spin foam amplitudes. The library improves on previous codes by many orders of magnitude in single-core performance, can be parallelized on a large number of CPUs and on the GPU, and can be used interactively. ...
gr-qc/0401065
Muhammad Sharif
M. Sharif
Dirac Equation in Standard Cosmological Models
null
Chin.J.Phys.40:526-531,2002
null
null
gr-qc
null
The time equation associated to the Dirac Equation (DE) is studied for the radiation-dominated Friedmann-Robertson-Walker (FRW) universe. The results are analysed for small and large values of time. We also incorporate the corrections of the paper studied by Zecca [1] for the matter-dominated FRW universe.
[ { "created": "Thu, 15 Jan 2004 13:01:34 GMT", "version": "v1" } ]
2008-11-07
[ [ "Sharif", "M.", "" ] ]
The time equation associated to the Dirac Equation (DE) is studied for the radiation-dominated Friedmann-Robertson-Walker (FRW) universe. The results are analysed for small and large values of time. We also incorporate the corrections of the paper studied by Zecca [1] for the matter-dominated FRW universe.
2311.14130
Neev Khera
Abhay Ashtekar, Neev Khera
Unified Treatment of Null and Spatial Infinity III: Asymptotically Minkowski Space-times
References and minor clarifications added. Version to appear in JHEP. 36 pages, 1 figure
JHEP02(2024)210
10.1007/JHEP02(2024)210
ArXiv ePrint: 2311.14130
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The Spi framework provides a 4-dimensional approach to investigate the asymptotic properties of gravitational fields as one recedes from isolated systems in any space-like direction, without reference to a Cauchy surface. It is well suited to unify descriptions at null and spatial infinity because $\mathscr{I}$ arise...
[ { "created": "Thu, 23 Nov 2023 17:57:55 GMT", "version": "v1" }, { "created": "Fri, 19 Jan 2024 14:05:32 GMT", "version": "v2" } ]
2024-03-13
[ [ "Ashtekar", "Abhay", "" ], [ "Khera", "Neev", "" ] ]
The Spi framework provides a 4-dimensional approach to investigate the asymptotic properties of gravitational fields as one recedes from isolated systems in any space-like direction, without reference to a Cauchy surface. It is well suited to unify descriptions at null and spatial infinity because $\mathscr{I}$ arises ...
gr-qc/0311078
Patricio S. Letelier
Guillermo A. Gonzalez and Patricio S. Letelier
Exact General Relativistic Thick Disks
11 pages, RevTex, 9 eps figs. Accepted for publication in PRD
Phys.Rev. D69 (2004) 044013
10.1103/PhysRevD.69.044013
null
gr-qc astro-ph
null
A method to construct exact general relativistic thick disks that is a simple generalization of the ``displace, cut and reflect'' method commonly used in Newtonian, as well as, in Einstein theory of gravitation is presented. This generalization consists in the addition of a new step in the above mentioned method. The...
[ { "created": "Mon, 24 Nov 2003 12:23:02 GMT", "version": "v1" } ]
2009-11-10
[ [ "Gonzalez", "Guillermo A.", "" ], [ "Letelier", "Patricio S.", "" ] ]
A method to construct exact general relativistic thick disks that is a simple generalization of the ``displace, cut and reflect'' method commonly used in Newtonian, as well as, in Einstein theory of gravitation is presented. This generalization consists in the addition of a new step in the above mentioned method. The n...
1009.0936
Philippe G. LeFloch
Philippe G. LeFloch and Luc Rozoy
Uniqueness of Kottler spacetime and Besse conjecture
4 pages
null
null
null
gr-qc math.AP math.DG
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We establish a black hole uniqueness theorem for Schwarzschild-de Sitter spacetime, also called Kottler spacetime, which satisfies Einstein's field equations of general relativity with positive cosmological constant. Our result concerns the class of static vacuum spacetimes with compact spacelike slices and regular m...
[ { "created": "Sun, 5 Sep 2010 17:45:20 GMT", "version": "v1" }, { "created": "Thu, 9 Sep 2010 18:57:50 GMT", "version": "v2" } ]
2010-09-10
[ [ "LeFloch", "Philippe G.", "" ], [ "Rozoy", "Luc", "" ] ]
We establish a black hole uniqueness theorem for Schwarzschild-de Sitter spacetime, also called Kottler spacetime, which satisfies Einstein's field equations of general relativity with positive cosmological constant. Our result concerns the class of static vacuum spacetimes with compact spacelike slices and regular max...
1107.2916
Lorenzo Iorio
Lorenzo Iorio
Perturbed stellar motions around the rotating black hole in Sgr A* for a generic orientation of its spin axis
LaTex2e, 10 pages, 4 tables, no figures, 72 references. Sign error corrected in Eq. (8), in the correspondence Q_2-->J_2, and in the precessional formulas. Clarification about the mean anomaly precession added
Phys.Rev.D84:124001,2011
10.1103/PhysRevD.84.124001
null
gr-qc astro-ph.GA physics.geo-ph physics.space-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Empirically determining the averaged variations of the orbital parameters of the stars orbiting the Supermassive Black Hole (SBH) hosted by the Galactic Centre (GC) in Sgr A* is, in principle, a valuable tool to put on the test the General Theory of Relativity (GTR), in regimes far stronger than those tested so far, ...
[ { "created": "Thu, 14 Jul 2011 08:59:09 GMT", "version": "v1" }, { "created": "Tue, 2 Aug 2011 15:24:54 GMT", "version": "v2" }, { "created": "Wed, 3 Aug 2011 14:01:54 GMT", "version": "v3" }, { "created": "Wed, 9 Nov 2011 19:44:08 GMT", "version": "v4" }, { "crea...
2017-10-06
[ [ "Iorio", "Lorenzo", "" ] ]
Empirically determining the averaged variations of the orbital parameters of the stars orbiting the Supermassive Black Hole (SBH) hosted by the Galactic Centre (GC) in Sgr A* is, in principle, a valuable tool to put on the test the General Theory of Relativity (GTR), in regimes far stronger than those tested so far, an...
gr-qc/0005014
V. Guruprasad
V Guruprasad
Relativity of spatial scale and of the Hubble flow: The logical foundations of relativity and cosmology
8 pages
null
null
null
gr-qc
null
Formalising the logical dependence of physical quantities on material referents of scale, I show that both Hubble's law and the cosmological constant are in fact exactly replicable by a spatial contraction of referents locally on earth, and that the Pioneer anomaly is irrefutable indication that this is the case. The...
[ { "created": "Thu, 4 May 2000 12:25:20 GMT", "version": "v1" } ]
2007-05-23
[ [ "Guruprasad", "V", "" ] ]
Formalising the logical dependence of physical quantities on material referents of scale, I show that both Hubble's law and the cosmological constant are in fact exactly replicable by a spatial contraction of referents locally on earth, and that the Pioneer anomaly is irrefutable indication that this is the case. The f...
2004.04878
Gesiel Rodrigues
G. Rodrigues-da-Silva and L. G. Medeiros
Spherically Symmetric Solutions in Higher-Derivative Theories of Gravity
10 pages, 2 tables. To incorporate the referee's comments, in this version that matches the one published in Phys. Rev. D, we expanded the discussion in the stability analysis, the references were updated and there were improvements throughout the text
Phys. Rev. D 101, 124061 (2020)
10.1103/PhysRevD.101.124061
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Higher-order theories of gravity have received much attention from several areas including quantum gravity, string theory and cosmology. This paper proposes a higher-order gravity whose action includes all curvature scalar terms up to the second-order corrections of general relativity, namely, $R^{2}$, $R^{3}$ and $R...
[ { "created": "Fri, 10 Apr 2020 01:55:49 GMT", "version": "v1" }, { "created": "Sat, 25 Apr 2020 03:11:00 GMT", "version": "v2" }, { "created": "Mon, 3 Aug 2020 15:27:13 GMT", "version": "v3" } ]
2020-08-04
[ [ "Rodrigues-da-Silva", "G.", "" ], [ "Medeiros", "L. G.", "" ] ]
Higher-order theories of gravity have received much attention from several areas including quantum gravity, string theory and cosmology. This paper proposes a higher-order gravity whose action includes all curvature scalar terms up to the second-order corrections of general relativity, namely, $R^{2}$, $R^{3}$ and $R\s...
2306.02279
Andrzej Odrzywolek
Patryk Mach and Andrzej Odrzywo{\l}ek
Equatorial accretion on the Kerr black hole
Accepted to Acta Phys. Pol. B Proc. Suppl. Animated Fig. 1. Talk presented at the 8th Conference of the Polish Society on Relativity (POTOR8), 19-23 September 2022, Banach Center IMPAN, Warsaw, Poland
null
null
null
gr-qc astro-ph.GA hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We investigate stationary accretion of the collisionless Vlasov gas onto the Kerr black hole, occurring in the equatorial plane. At infinity the gas obeys the Maxwell-J\"{u}ttner distribution, restricted to the equatorial plane. In the vicinity of the black hole, the motion of the gas is governed by the spacetime geo...
[ { "created": "Sun, 4 Jun 2023 06:56:15 GMT", "version": "v1" } ]
2023-06-06
[ [ "Mach", "Patryk", "" ], [ "Odrzywołek", "Andrzej", "" ] ]
We investigate stationary accretion of the collisionless Vlasov gas onto the Kerr black hole, occurring in the equatorial plane. At infinity the gas obeys the Maxwell-J\"{u}ttner distribution, restricted to the equatorial plane. In the vicinity of the black hole, the motion of the gas is governed by the spacetime geome...
1610.05635
Jessie Durk
Jessie Durk, Timothy Clifton
Exact Initial Data for Black Hole Universes with a Cosmological Constant
19 pages, 5 figures, v2: matches published version
Class. Quantum Grav. 34 (2017) 065009
10.1088/1361-6382/aa6064
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We construct exact initial data for closed cosmological models filled with regularly arranged black holes in the presence of $\Lambda$. The intrinsic geometry of the 3-dimensional space described by this data is a sum of simple closed-form expressions, while the extrinsic curvature is just proportional to $\Lambda$. ...
[ { "created": "Tue, 18 Oct 2016 14:27:37 GMT", "version": "v1" }, { "created": "Wed, 8 Mar 2017 12:14:38 GMT", "version": "v2" } ]
2017-03-15
[ [ "Durk", "Jessie", "" ], [ "Clifton", "Timothy", "" ] ]
We construct exact initial data for closed cosmological models filled with regularly arranged black holes in the presence of $\Lambda$. The intrinsic geometry of the 3-dimensional space described by this data is a sum of simple closed-form expressions, while the extrinsic curvature is just proportional to $\Lambda$. We...
gr-qc/0502076
Hamid Reza Sepangi
B. Vakili, S. Jalalzadeh and H. R. Sepangi
Classical and quantum spinor cosmology with signature change
13 pages, 4 figures
JCAP 0505 (2005) 006
10.1088/1475-7516/2005/05/006
null
gr-qc hep-th
null
We study the classical and quantum cosmology of a universe in which the matter source is a massive Dirac spinor field and consider cases where such fields are either free or self-interacting. We focus attention on the spatially flat Robertson-Walker cosmology and classify the solutions of the Einstein-Dirac system in...
[ { "created": "Wed, 16 Feb 2005 16:38:21 GMT", "version": "v1" }, { "created": "Sat, 14 May 2005 11:29:32 GMT", "version": "v2" } ]
2009-11-11
[ [ "Vakili", "B.", "" ], [ "Jalalzadeh", "S.", "" ], [ "Sepangi", "H. R.", "" ] ]
We study the classical and quantum cosmology of a universe in which the matter source is a massive Dirac spinor field and consider cases where such fields are either free or self-interacting. We focus attention on the spatially flat Robertson-Walker cosmology and classify the solutions of the Einstein-Dirac system in t...