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gr-qc/0610137
Arkady A. Popov
A. A. Popov, R. K. Muharlyamov
Local spherically symmetric perturbations of spatially flat Friedmann models
iopart, 10 pages
null
null
KGPU-06-1
gr-qc astro-ph
null
The spherically symmetric perturbations in the spatially flat Friedman models are considered. It is assumed that the Friedmannian density and pressure are related through a linear equation of state. The perturbation is joined smoothly with an unperturbed Friedmann's background at the sound horizon of perturbation. Such junction is in accordance with the "birth" of a local perturbation as a result of the redistribution of matter. The solution of the Einstein's equations is obtained in linear approximation on a Friedmann's background near the the sound horizon of perturbation.
[ { "created": "Fri, 27 Oct 2006 08:23:22 GMT", "version": "v1" } ]
2007-05-23
[ [ "Popov", "A. A.", "" ], [ "Muharlyamov", "R. K.", "" ] ]
The spherically symmetric perturbations in the spatially flat Friedman models are considered. It is assumed that the Friedmannian density and pressure are related through a linear equation of state. The perturbation is joined smoothly with an unperturbed Friedmann's background at the sound horizon of perturbation. Such junction is in accordance with the "birth" of a local perturbation as a result of the redistribution of matter. The solution of the Einstein's equations is obtained in linear approximation on a Friedmann's background near the the sound horizon of perturbation.
2404.11723
Sourav Chowdhury Roy
Sourav Roy Chowdhury, Debabrata Deb, Farook Rahaman, Saibal Ray
Finslerian extension of an anisotropic strange star in the domain of modified gravity
Accepted for publication in EPJC
null
null
null
gr-qc
http://creativecommons.org/licenses/by-sa/4.0/
In this article, we apply the Finsler spacetime to develop the Einstein field equations in the extension of modified geometry. Following Finsler geometry, which is focused on the tangent bundle with a scalar function, a scalar equation should be the field equation that defines this structure. This spacetime maintains the required causality properties on the generalized Lorentzian metric manifold. The matter field is coupled with the Finsler geometry to produce the complete action. In this work, we use modified gravity to develop the Einstein field equations from the variational principle. Developed Einstein field equations are employed on the strange stellar system to improve the study. The interior of the system is made of a strange quark, maintained by the MIT Bag equation of state. In addition, the modified Tolman-Oppenheimer-Volkov (TOV) equation is formulated. In particular, the anisotropic stress attains the maximum at the surface. The mass-central density variation justifies the stability of the system.
[ { "created": "Wed, 17 Apr 2024 20:20:40 GMT", "version": "v1" } ]
2024-04-19
[ [ "Chowdhury", "Sourav Roy", "" ], [ "Deb", "Debabrata", "" ], [ "Rahaman", "Farook", "" ], [ "Ray", "Saibal", "" ] ]
In this article, we apply the Finsler spacetime to develop the Einstein field equations in the extension of modified geometry. Following Finsler geometry, which is focused on the tangent bundle with a scalar function, a scalar equation should be the field equation that defines this structure. This spacetime maintains the required causality properties on the generalized Lorentzian metric manifold. The matter field is coupled with the Finsler geometry to produce the complete action. In this work, we use modified gravity to develop the Einstein field equations from the variational principle. Developed Einstein field equations are employed on the strange stellar system to improve the study. The interior of the system is made of a strange quark, maintained by the MIT Bag equation of state. In addition, the modified Tolman-Oppenheimer-Volkov (TOV) equation is formulated. In particular, the anisotropic stress attains the maximum at the surface. The mass-central density variation justifies the stability of the system.
2309.14925
Donato Bini
Donato Bini, Thibault Damour, Andrea Geralico
Comparing One-loop Gravitational Bremsstrahlung Amplitudes to the Multipolar-Post-Minkowskian Waveform
23 pages, 2 figures; V2: new Sec. 9 and new references added, minor text modifications; V3: corrected Eqs 8.11, 8.12, 8.13 (and consequently Eq. 9.14), one reference added
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We compare recent one-loop-level, scattering-amplitude-based, computations of the classical part of the gravitational bremsstrahlung waveform to the frequency-domain version of the corresponding Multipolar-Post-Minkowskian waveform result. When referring the one-loop result to the classical averaged momenta $\bar p_a = \frac12 (p_a+p'_a)$, the two waveforms are found to agree at the Newtonian and first post-Newtonian levels, as well as at the first-and-a-half post-Newtonian level, i.e. for the leading-order quadrupolar tail. However, we find that there are significant differences at the second-and-a-half post-Newtonian level, $O\left( \frac{G^2}{c^5} \right)$, i.e. when reaching: (i) the first post-Newtonian correction to the linear quadrupole tail; (ii) Newtonian-level linear tails of higher multipolarity (odd octupole and even hexadecapole); (iii) radiation-reaction effects on the worldlines; and (iv) various contributions of cubically nonlinear origin (notably linked to the quadrupole$\times$ quadrupole$\times$ quadrupole coupling in the wavezone). These differences are reflected at the sub-sub-sub-leading level in the soft expansion, $ \sim \omega \ln \omega $, i.e. $O\left(\frac{1}{t^2} \right)$ in the time domain. Finally, we computed the first four terms of the low-frequency expansion of the Multipolar-Post-Minkowskian waveform and checked that they agree with the corresponding existing classical soft graviton results.
[ { "created": "Tue, 26 Sep 2023 13:34:04 GMT", "version": "v1" }, { "created": "Wed, 15 Nov 2023 14:18:45 GMT", "version": "v2" }, { "created": "Sat, 3 Feb 2024 16:18:44 GMT", "version": "v3" } ]
2024-02-06
[ [ "Bini", "Donato", "" ], [ "Damour", "Thibault", "" ], [ "Geralico", "Andrea", "" ] ]
We compare recent one-loop-level, scattering-amplitude-based, computations of the classical part of the gravitational bremsstrahlung waveform to the frequency-domain version of the corresponding Multipolar-Post-Minkowskian waveform result. When referring the one-loop result to the classical averaged momenta $\bar p_a = \frac12 (p_a+p'_a)$, the two waveforms are found to agree at the Newtonian and first post-Newtonian levels, as well as at the first-and-a-half post-Newtonian level, i.e. for the leading-order quadrupolar tail. However, we find that there are significant differences at the second-and-a-half post-Newtonian level, $O\left( \frac{G^2}{c^5} \right)$, i.e. when reaching: (i) the first post-Newtonian correction to the linear quadrupole tail; (ii) Newtonian-level linear tails of higher multipolarity (odd octupole and even hexadecapole); (iii) radiation-reaction effects on the worldlines; and (iv) various contributions of cubically nonlinear origin (notably linked to the quadrupole$\times$ quadrupole$\times$ quadrupole coupling in the wavezone). These differences are reflected at the sub-sub-sub-leading level in the soft expansion, $ \sim \omega \ln \omega $, i.e. $O\left(\frac{1}{t^2} \right)$ in the time domain. Finally, we computed the first four terms of the low-frequency expansion of the Multipolar-Post-Minkowskian waveform and checked that they agree with the corresponding existing classical soft graviton results.
1707.00667
Simone Speziale
Elena De Paoli and Simone Speziale
Sachs' free data in real connection variables
23 pages + Appendix, 2 figures. v2: Improved text and some amendments throughout, added more details on the relation between 2+2 foliations and null tetrads, updated references. Version submitted for peer reviewing. v3: Few minor amendments, footnote added on a null congruence in the presence of torsion; matches published version
null
10.1007/JHEP11(2017)205
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We discuss the Hamiltonian dynamics of general relativity with real connection variables on a null foliation, and use the Newman-Penrose formalism to shed light on the geometric meaning of the various constraints. We identify the equivalent of Sachs' constraint-free initial data as projections of connection components related to null rotations, i.e. the translational part of the ISO(2) group stabilising the internal null direction soldered to the hypersurface. A pair of second-class constraints reduces these connection components to the shear of a null geodesic congruence, thus establishing equivalence with the second-order formalism, which we show in details at the level of symplectic potentials. A special feature of the first-order formulation is that Sachs' propagating equations for the shear, away from the initial hypersurface, are turned into tertiary constraints; their role is to preserve the relation between connection and shear under retarded time evolution. The conversion of wave-like propagating equations into constraints is possible thanks to an algebraic Bianchi identity; the same one that allows one to describe the radiative data at future null infinity in terms of a shear of a (non-geodesic) asymptotic null vector field in the physical spacetime. Finally, we compute the modification to the spin coefficients and the null congruence in the presence of torsion.
[ { "created": "Mon, 3 Jul 2017 17:36:35 GMT", "version": "v1" }, { "created": "Tue, 19 Sep 2017 17:07:51 GMT", "version": "v2" }, { "created": "Tue, 5 Dec 2017 18:53:06 GMT", "version": "v3" } ]
2018-01-17
[ [ "De Paoli", "Elena", "" ], [ "Speziale", "Simone", "" ] ]
We discuss the Hamiltonian dynamics of general relativity with real connection variables on a null foliation, and use the Newman-Penrose formalism to shed light on the geometric meaning of the various constraints. We identify the equivalent of Sachs' constraint-free initial data as projections of connection components related to null rotations, i.e. the translational part of the ISO(2) group stabilising the internal null direction soldered to the hypersurface. A pair of second-class constraints reduces these connection components to the shear of a null geodesic congruence, thus establishing equivalence with the second-order formalism, which we show in details at the level of symplectic potentials. A special feature of the first-order formulation is that Sachs' propagating equations for the shear, away from the initial hypersurface, are turned into tertiary constraints; their role is to preserve the relation between connection and shear under retarded time evolution. The conversion of wave-like propagating equations into constraints is possible thanks to an algebraic Bianchi identity; the same one that allows one to describe the radiative data at future null infinity in terms of a shear of a (non-geodesic) asymptotic null vector field in the physical spacetime. Finally, we compute the modification to the spin coefficients and the null congruence in the presence of torsion.
0705.1765
Dr. Anirudh Pradhan
Anirudh Pradhan, Mukesh Kumar Mishra and Anil Kumar Yadav
A New Class of String Cosmological Models in Cylindrically Symmetric Inhomogeneous Universe
14 pages. arXiv admin note: substantial text overlap with arXiv:0705.0904
Rom. J. Phys. 54:747-762,2009
null
null
gr-qc
null
A new class of cylindrically symmetric inhomogeneous string cosmological models is investigated. To get the deterministic solution, it has been assumed that the expansion ($\theta$) in the model is proportional to the eigen value $\sigma^{1}_{1}$ of the shear tensor $\sigma^{i}_{j}$. The physical and geometric aspects of the model are also discussed.
[ { "created": "Sat, 12 May 2007 11:08:33 GMT", "version": "v1" }, { "created": "Tue, 24 Jul 2007 13:48:34 GMT", "version": "v2" } ]
2018-07-10
[ [ "Pradhan", "Anirudh", "" ], [ "Mishra", "Mukesh Kumar", "" ], [ "Yadav", "Anil Kumar", "" ] ]
A new class of cylindrically symmetric inhomogeneous string cosmological models is investigated. To get the deterministic solution, it has been assumed that the expansion ($\theta$) in the model is proportional to the eigen value $\sigma^{1}_{1}$ of the shear tensor $\sigma^{i}_{j}$. The physical and geometric aspects of the model are also discussed.
2006.03229
Kai Lin
Kai Lin and Wei-Liang Qian
Cosmic evolution of dark energy in a generalized Rastall gravity
Accepted by the European Physical Journal C
null
10.1140/epjc/s10052-020-8116-2
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this work, we propose a scheme for cosmic evolution in a generalized Rastall gravity. In our approach, the role of dark energy is taken by the non-conserved sector of the stress energy-momentum tensor. The resultant cosmic evolution is found to naturally consists of three stages, namely, radiation dominated, ordinary matter dominated, as well as dark energy and dark matter dominated eras. Furthermore, for the present model, it is demonstrated that the eventual fate of the Universe is mostly insensitive to the initial conditions, in contrast to the standard $\Lambda$CDM model. In particular, the solution displays the properties of a dynamic attractor, which is reminiscent of quintessence and k-essence models. Subsequently, the cosmic coincidence problem is averted. The amount of deviation from a conserved stress energy-momentum tensor is shown to be more remarkable during the period when the dark energy evolves more rapidly. On the other hand, the conservation law is largely restored for the infinite past and future. The implications of the present approach are addressed.
[ { "created": "Fri, 5 Jun 2020 04:38:54 GMT", "version": "v1" } ]
2020-06-08
[ [ "Lin", "Kai", "" ], [ "Qian", "Wei-Liang", "" ] ]
In this work, we propose a scheme for cosmic evolution in a generalized Rastall gravity. In our approach, the role of dark energy is taken by the non-conserved sector of the stress energy-momentum tensor. The resultant cosmic evolution is found to naturally consists of three stages, namely, radiation dominated, ordinary matter dominated, as well as dark energy and dark matter dominated eras. Furthermore, for the present model, it is demonstrated that the eventual fate of the Universe is mostly insensitive to the initial conditions, in contrast to the standard $\Lambda$CDM model. In particular, the solution displays the properties of a dynamic attractor, which is reminiscent of quintessence and k-essence models. Subsequently, the cosmic coincidence problem is averted. The amount of deviation from a conserved stress energy-momentum tensor is shown to be more remarkable during the period when the dark energy evolves more rapidly. On the other hand, the conservation law is largely restored for the infinite past and future. The implications of the present approach are addressed.
gr-qc/0110076
Zbigniew Haba
Z. Haba (Institute of Theoretical Physics, Wroclaw University)
Universal regular short distance behavior from an interaction with a scale invariant gravity
LaTeX, 4 pages
Phys.Lett. B528 (2002) 129-132
10.1016/S0370-2693(02)01193-0
null
gr-qc hep-th
null
We assume that the fourdimensional quantum gravity is scale invariant at short distances. We show through a simple scaling argument that correlation functions of quantum fields interacting with gravity have a universal (more regular) short distance behavior.
[ { "created": "Wed, 17 Oct 2001 09:01:25 GMT", "version": "v1" } ]
2009-11-07
[ [ "Haba", "Z.", "", "Institute of Theoretical Physics, Wroclaw University" ] ]
We assume that the fourdimensional quantum gravity is scale invariant at short distances. We show through a simple scaling argument that correlation functions of quantum fields interacting with gravity have a universal (more regular) short distance behavior.
gr-qc/0102063
Larry Ford
L.H. Ford and Chun-Hsien Wu
Stress Tensor Fluctuations and Passive Quantum Gravity
13 pages. Based on a talk given at the 5th Peyresq workshop. Revised version incorporates corrections in several expressions in Sect. 5
Int.J.Theor.Phys. 42 (2003) 15-26
null
null
gr-qc
null
The quantum fluctuation of the stress tensor of a quantum field are discussed, as are the resulting spacetime metric fluctuations. Passive quantum gravity is an approximation in which gravity is not directly quantized, but fluctuations of the spacetime geometry are driven by stress tensor fluctuations. We discuss a decomposition of the stress tensor correlation function into three parts, and consider the physical implications of each part. The operational significance of metric fluctuations and the possible limits of validity of semiclassical gravity are discussed.
[ { "created": "Tue, 13 Feb 2001 20:42:26 GMT", "version": "v1" }, { "created": "Tue, 29 May 2001 20:06:08 GMT", "version": "v2" } ]
2007-05-23
[ [ "Ford", "L. H.", "" ], [ "Wu", "Chun-Hsien", "" ] ]
The quantum fluctuation of the stress tensor of a quantum field are discussed, as are the resulting spacetime metric fluctuations. Passive quantum gravity is an approximation in which gravity is not directly quantized, but fluctuations of the spacetime geometry are driven by stress tensor fluctuations. We discuss a decomposition of the stress tensor correlation function into three parts, and consider the physical implications of each part. The operational significance of metric fluctuations and the possible limits of validity of semiclassical gravity are discussed.
1108.1835
Theodore A. Jacobson
David Garfinkle and Ted Jacobson
A positive energy theorem for Einstein-aether and Ho\v{r}ava gravity
4 pages
null
10.1103/PhysRevLett.107.191102
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Energy positivity is established for a class of solutions to Einstein-aether theory and the IR limit of Ho\v{r}ava gravity within a certain range of coupling parameters. The class consists of solutions where the aether 4-vector is divergence free on a spacelike surface to which it is orthogonal (which implies that the surface is maximal). In particular, this result holds for spherically symmetric solutions at a moment of time symmetry.
[ { "created": "Tue, 9 Aug 2011 00:33:25 GMT", "version": "v1" } ]
2013-05-29
[ [ "Garfinkle", "David", "" ], [ "Jacobson", "Ted", "" ] ]
Energy positivity is established for a class of solutions to Einstein-aether theory and the IR limit of Ho\v{r}ava gravity within a certain range of coupling parameters. The class consists of solutions where the aether 4-vector is divergence free on a spacelike surface to which it is orthogonal (which implies that the surface is maximal). In particular, this result holds for spherically symmetric solutions at a moment of time symmetry.
1012.4207
Tonguc Rador
Tongu\c{c} Rador, Sava\c{s} Arapo\u{g}lu and \.Ibrahim Semiz
Comment on "Model for Gravity at Large Distances"
We have been informed on Dec.22, 2010 that an erratum was sent to PRL before we wrote the present comment. Due to a communication problem we were unaware of this fact. But we believe our comment goes beyond a correction, and adds to the physics
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We correct a sign mistake in the work mentioned in the title; explore consequences on energy conditions in the relevant context, and make a suggestion on the introduced parameter.
[ { "created": "Sun, 19 Dec 2010 20:56:00 GMT", "version": "v1" }, { "created": "Thu, 23 Dec 2010 11:59:36 GMT", "version": "v2" } ]
2010-12-24
[ [ "Rador", "Tonguç", "" ], [ "Arapoğlu", "Savaş", "" ], [ "Semiz", "İbrahim", "" ] ]
We correct a sign mistake in the work mentioned in the title; explore consequences on energy conditions in the relevant context, and make a suggestion on the introduced parameter.
gr-qc/0506095
Valerio Faraoni
Valerio Faraoni (Bishop's University)
Phantom cosmology with general potentials
16 pages, LaTeX, to appear in Class. Quant. Grav
Class.Quant.Grav. 22 (2005) 3235-3246
10.1088/0264-9381/22/16/008
null
gr-qc astro-ph hep-th
null
We present a unified treatment of the phase space of a spatially flat homogeneous and isotropic universe dominated by a phantom field. Results on the dynamics and the late time attractors (Big Rip, de Sitter, etc.) are derived without specifying the form of the phantom potential, using only general assumptions on its shape. Many results found in the literature are quickly recovered and predictions are made for new scenarios.
[ { "created": "Fri, 17 Jun 2005 16:14:50 GMT", "version": "v1" } ]
2009-11-11
[ [ "Faraoni", "Valerio", "", "Bishop's University" ] ]
We present a unified treatment of the phase space of a spatially flat homogeneous and isotropic universe dominated by a phantom field. Results on the dynamics and the late time attractors (Big Rip, de Sitter, etc.) are derived without specifying the form of the phantom potential, using only general assumptions on its shape. Many results found in the literature are quickly recovered and predictions are made for new scenarios.
0706.2616
Roald Sosnovskiy
Roald Sosnovskiy
The gravitational energy for stationary space-time
4 pages
null
null
null
gr-qc
null
It is prove, that the gravity field energy formulas obtained for static systems on the ground of local energy conservation law by test-particles fall, is suitable for stationary systems.
[ { "created": "Mon, 18 Jun 2007 14:59:58 GMT", "version": "v1" } ]
2007-06-19
[ [ "Sosnovskiy", "Roald", "" ] ]
It is prove, that the gravity field energy formulas obtained for static systems on the ground of local energy conservation law by test-particles fall, is suitable for stationary systems.
1503.01672
Burkhard Kleihaus
Burkhard Kleihaus (1), Jutta Kunz (1), and Stoytcho Yazadjiev (2) ((1) University of Oldenburg, (2) Sofia University)
Scalarized Hairy Black Holes
11 pages, 4 figures
Physics Letters B 744 (2015) 406
10.1016/j.physletb.2015.04.014
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the presence of a complex scalar field scalar-tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and ordinary hairy black holes. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.
[ { "created": "Thu, 5 Mar 2015 15:56:05 GMT", "version": "v1" } ]
2015-04-24
[ [ "Kleihaus", "Burkhard", "" ], [ "Kunz", "Jutta", "" ], [ "Yazadjiev", "Stoytcho", "" ] ]
In the presence of a complex scalar field scalar-tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and ordinary hairy black holes. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.
0910.1254
Gerhard Rein
Hakan Andreasson, Gerhard Rein
Formation of trapped surfaces for the spherically symmetric Einstein-Vlasov system
27
J.Hyperbol.Diff.Equat.7:707-731,2010
10.1142/S0219891610002268
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider the spherically symmetric, asymptotically flat, non-vacuum Einstein equations, using as matter model a collisionless gas as described by the Vlasov equation. We find explicit conditions on the initial data which guarantee the formation of a trapped surface in the evolution which in particular implies that weak cosmic censorship holds for these data. We also analyze the evolution of solutions after a trapped surface has formed and we show that the event horizon is future complete. Furthermore we find that the apparent horizon and the event horizon do not coincide. This behavior is analogous to what is found in certain Vaidya spacetimes. The analysis is carried out in Eddington-Finkelstein coordinates.
[ { "created": "Wed, 7 Oct 2009 13:20:28 GMT", "version": "v1" } ]
2011-03-22
[ [ "Andreasson", "Hakan", "" ], [ "Rein", "Gerhard", "" ] ]
We consider the spherically symmetric, asymptotically flat, non-vacuum Einstein equations, using as matter model a collisionless gas as described by the Vlasov equation. We find explicit conditions on the initial data which guarantee the formation of a trapped surface in the evolution which in particular implies that weak cosmic censorship holds for these data. We also analyze the evolution of solutions after a trapped surface has formed and we show that the event horizon is future complete. Furthermore we find that the apparent horizon and the event horizon do not coincide. This behavior is analogous to what is found in certain Vaidya spacetimes. The analysis is carried out in Eddington-Finkelstein coordinates.
1801.06614
Annegret Y. Burtscher
Lars Andersson and Annegret Y. Burtscher
On the asymptotic behavior of static perfect fluids
32 pages; minor changes in v2, final version
Annales Henri Poincar\'e, Volume 20, Issue 3 (2019), pp 813-857
10.1007/s00023-018-00758-z
null
gr-qc math-ph math.DG math.DS math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Static spherically symmetric solutions to the Einstein-Euler equations with prescribed central densities are known to exist, be unique and smooth for reasonable equations of state. Some criteria are also available to decide whether solutions have finite extent (stars with a vacuum exterior) or infinite extent. In the latter case, the matter extends globally with the density approaching zero at infinity. The asymptotic behavior largely depends on the equation of state of the fluid and is still poorly understood. While a few such unbounded solutions are known to be asymptotically flat with finite ADM mass, the vast majority are not. We provide a full geometric description of the asymptotic behavior of static spherically symmetric perfect fluid solutions with linear and polytropic-type equations of state with index n>5. In order to capture the asymptotic behavior we introduce a notion of scaled quasi-asymptotic flatness, which encodes a form of asymptotic conicality. In particular, these spacetimes are asymptotically simple.
[ { "created": "Sat, 20 Jan 2018 02:10:16 GMT", "version": "v1" }, { "created": "Wed, 23 Jan 2019 17:09:00 GMT", "version": "v2" } ]
2019-03-01
[ [ "Andersson", "Lars", "" ], [ "Burtscher", "Annegret Y.", "" ] ]
Static spherically symmetric solutions to the Einstein-Euler equations with prescribed central densities are known to exist, be unique and smooth for reasonable equations of state. Some criteria are also available to decide whether solutions have finite extent (stars with a vacuum exterior) or infinite extent. In the latter case, the matter extends globally with the density approaching zero at infinity. The asymptotic behavior largely depends on the equation of state of the fluid and is still poorly understood. While a few such unbounded solutions are known to be asymptotically flat with finite ADM mass, the vast majority are not. We provide a full geometric description of the asymptotic behavior of static spherically symmetric perfect fluid solutions with linear and polytropic-type equations of state with index n>5. In order to capture the asymptotic behavior we introduce a notion of scaled quasi-asymptotic flatness, which encodes a form of asymptotic conicality. In particular, these spacetimes are asymptotically simple.
1107.3322
Vyacheslav Ivanovich Dokuchaev
Vyacheslav I. Dokuchaev and Yury N. Eroshenko
Accretion with back reaction
5 pages, 2 figures; new figure and references added
Phys. Rev. D 84, 124022 (2011)
10.1103/PhysRevD.84.124022
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We calculate analytically a back reaction of the stationary spherical accretion flow near the event horizon and near the inner Cauchy horizon of the charged black hole. It is shown that corresponding back-reaction corrections to the black hole metric depend only on the fluid accretion rate and diverge in the case of an extremely charged black hole. In result, the test fluid approximation for stationary accretion is violated for extreme black holes. This behavior of the accreting black hole is in accordance with the third law of black hole thermodynamics, forbidding the practical attainability of the extreme state.
[ { "created": "Sun, 17 Jul 2011 18:42:03 GMT", "version": "v1" }, { "created": "Mon, 19 Dec 2011 15:02:51 GMT", "version": "v2" } ]
2011-12-20
[ [ "Dokuchaev", "Vyacheslav I.", "" ], [ "Eroshenko", "Yury N.", "" ] ]
We calculate analytically a back reaction of the stationary spherical accretion flow near the event horizon and near the inner Cauchy horizon of the charged black hole. It is shown that corresponding back-reaction corrections to the black hole metric depend only on the fluid accretion rate and diverge in the case of an extremely charged black hole. In result, the test fluid approximation for stationary accretion is violated for extreme black holes. This behavior of the accreting black hole is in accordance with the third law of black hole thermodynamics, forbidding the practical attainability of the extreme state.
2312.03242
Tayyab Naseer
M. Sharif, Tayyab Naseer
Impact of Charge on Complexity Analysis and Isotropic Decoupled Solutions in $f(\mathbb{R},\mathbb{T})$ Gravity
34 pages, 11 figures
Phys. Scr. 98(2023)115012
10.1088/1402-4896/acfce6
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we formulate two exact charged solutions to the field equations by extending the domain of existing anisotropic models with the help of minimal gravitational decoupling in $f(\mathbb{R},\mathbb{T})$ theory. For this, the anisotropic fluid distribution is considered as a seed source that is extended through the inclusion of a new gravitational source. The influence of the later matter configuration is controlled by the decoupling parameter. We formulate the field equations corresponding to the total matter source that are then decoupled into two distinct sets by implementing a transformation only on the radial metric coefficient. Both of these under-determined sets correspond to their parent sources. Some well-behaved forms of the metric potentials are taken into account to deal with the first set of equations. On the other hand, we solve the second set corresponding to an additional source by taking different constraints on the matter sector. We then consider the radius and mass of a compact star $4U~1820-30$ to analyze the physical feasibility of the resulting solutions for a particular modified model. It is concluded that our resulting solutions show stable behavior for certain values of the decoupling parameter and charge.
[ { "created": "Wed, 6 Dec 2023 02:31:08 GMT", "version": "v1" } ]
2023-12-07
[ [ "Sharif", "M.", "" ], [ "Naseer", "Tayyab", "" ] ]
In this paper, we formulate two exact charged solutions to the field equations by extending the domain of existing anisotropic models with the help of minimal gravitational decoupling in $f(\mathbb{R},\mathbb{T})$ theory. For this, the anisotropic fluid distribution is considered as a seed source that is extended through the inclusion of a new gravitational source. The influence of the later matter configuration is controlled by the decoupling parameter. We formulate the field equations corresponding to the total matter source that are then decoupled into two distinct sets by implementing a transformation only on the radial metric coefficient. Both of these under-determined sets correspond to their parent sources. Some well-behaved forms of the metric potentials are taken into account to deal with the first set of equations. On the other hand, we solve the second set corresponding to an additional source by taking different constraints on the matter sector. We then consider the radius and mass of a compact star $4U~1820-30$ to analyze the physical feasibility of the resulting solutions for a particular modified model. It is concluded that our resulting solutions show stable behavior for certain values of the decoupling parameter and charge.
0908.2787
Philip Stephens Mr
Philip Stephens
Inflation from a Non-Local Theory of Gravity
5 Pages
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper studies the inflationary dynamics of a Non-Local Theory of gravity. This theory, based around derivatives of the Ricci Scalar in the Einstein-Hilbert action, was previously found to be Ghost free, and to give rise to a bouncing cosmology. Perturbation spectra are calculated and found to be similar to those for chaotic inflation.
[ { "created": "Wed, 19 Aug 2009 16:42:16 GMT", "version": "v1" } ]
2009-08-20
[ [ "Stephens", "Philip", "" ] ]
This paper studies the inflationary dynamics of a Non-Local Theory of gravity. This theory, based around derivatives of the Ricci Scalar in the Einstein-Hilbert action, was previously found to be Ghost free, and to give rise to a bouncing cosmology. Perturbation spectra are calculated and found to be similar to those for chaotic inflation.
gr-qc/0610141
Philip Tillman Mr.
P. Tillman
Deformation Quantization, Quantization, and the Klein-Gordon Equation
This is a proceedings to the Second International Conference on Quantum Theories and Renormalization Group in Gravity and Cosmology
J.Phys.A40:7017-7024,2007
10.1088/1751-8113/40/25/S55
null
gr-qc
null
The aim of this proceeding is to give a basic introduction to Deformation Quantization (DQ) to physicists. We compare DQ to canonical quantization and path integral methods. It is described how certain issues such as the roles of associativity, covariance, dynamics, and operator orderings are understood in the context of DQ. Convergence issues in DQ are mentioned. Additionally, we formulate the Klein-Gordon (KG) equation in DQ. Original results are discussed which include the exact construction of the Fedosov star-product on the dS and AdS space-times. Also, the KG equation is written down for these space-times. This is a proceedings to the Second International Conference on Quantum Theories and Renormalization Group in Gravity and Cosmology.
[ { "created": "Fri, 27 Oct 2006 14:32:24 GMT", "version": "v1" }, { "created": "Tue, 31 Oct 2006 19:46:24 GMT", "version": "v2" }, { "created": "Wed, 28 Feb 2007 19:24:21 GMT", "version": "v3" }, { "created": "Wed, 28 Feb 2007 21:52:49 GMT", "version": "v4" } ]
2008-11-26
[ [ "Tillman", "P.", "" ] ]
The aim of this proceeding is to give a basic introduction to Deformation Quantization (DQ) to physicists. We compare DQ to canonical quantization and path integral methods. It is described how certain issues such as the roles of associativity, covariance, dynamics, and operator orderings are understood in the context of DQ. Convergence issues in DQ are mentioned. Additionally, we formulate the Klein-Gordon (KG) equation in DQ. Original results are discussed which include the exact construction of the Fedosov star-product on the dS and AdS space-times. Also, the KG equation is written down for these space-times. This is a proceedings to the Second International Conference on Quantum Theories and Renormalization Group in Gravity and Cosmology.
2104.06359
Jorge Ovalle
J. Ovalle, E. Contreras, Z. Stuchlik
Kerr-de Sitter Black Hole Revisited
7 pages, 2 figures
Phys. Rev. D 103, 084016 (2021)
10.1103/PhysRevD.103.084016
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We interpret the cosmological constant as the energy of the vacuum, and under a minimum amount of assumptions, we show that it is deformed in the vicinity of a black hole. This leads us to reexamine the Kerr-de Sitter solution. We provide a new solution, simpler and geometrically richer, which shows the impact of the rotation in form of a warped curvature. We carry out a detailed and exact study on the new black hole solution, and we conclude with a conjecture regarding the possible impact of our results on alternative theories.
[ { "created": "Tue, 13 Apr 2021 17:05:54 GMT", "version": "v1" } ]
2021-04-14
[ [ "Ovalle", "J.", "" ], [ "Contreras", "E.", "" ], [ "Stuchlik", "Z.", "" ] ]
We interpret the cosmological constant as the energy of the vacuum, and under a minimum amount of assumptions, we show that it is deformed in the vicinity of a black hole. This leads us to reexamine the Kerr-de Sitter solution. We provide a new solution, simpler and geometrically richer, which shows the impact of the rotation in form of a warped curvature. We carry out a detailed and exact study on the new black hole solution, and we conclude with a conjecture regarding the possible impact of our results on alternative theories.
2203.05157
Xin Zhang
Qi-Ming Fu, Shao-Wen Wei, Li Zhao, Yu-Xiao Liu, Xin Zhang
Shadow and weak deflection angle of a black hole in nonlocal gravity
16 pages, 11 figures
Universe 8, 341 (2022)
10.3390/universe8070341
null
gr-qc hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Black hole shadow and gravitational lensing play important roles in testing gravitational theories in the strong field regime. As the first-order modifications from quantum gravity, the nonlocality can be manifested by black hole shadow and gravitational lensing. For example, the cut-off parameter introduced by nonlocality will affect the shape and size of the black hole shadow, and also affect the deflection angle of light rays. In this paper, we mainly investigate the effects of the nonlocality on the black hole shadow and the gravitational lensing for two types of rotating black holes in nonlocal gravity. It is found that the size of the black hole shadow decreases with the cut-off parameter since the nonlocality weakens the gravitational constant, and the shape of the shadow gets more deformed with the increase of the cut-off parameter. However, if the rotation parameter is small, the shape of the shadow is almost a circle even though the cut-off parameter approaches its maximum. The energy emission rate in both models is also studied. The results show that there is a peak for each curve and the peak decreases and shifts to the low frequency with the increase of the cut-off parameter. Besides, we also explore the shadow of both types of black holes surrounded by a nonmagnetized pressureless plasma which satisfies the separability condition. It is found that the plasma has a frequency-dependent dispersive effect on the size and shape of the black hole shadow. For the gravitational lensing, we find that the cut-off parameter of model A makes a positive contribution to the deflection angle, which can be compared with the contribution of the rotation parameter, while the cut-off parameter of model B makes a negative contribution which can be ignored. These results may be helpful for probing nonlocal gravity in future observations.
[ { "created": "Thu, 10 Mar 2022 05:09:39 GMT", "version": "v1" }, { "created": "Wed, 27 Apr 2022 12:45:34 GMT", "version": "v2" }, { "created": "Thu, 23 Jun 2022 03:15:17 GMT", "version": "v3" } ]
2022-06-24
[ [ "Fu", "Qi-Ming", "" ], [ "Wei", "Shao-Wen", "" ], [ "Zhao", "Li", "" ], [ "Liu", "Yu-Xiao", "" ], [ "Zhang", "Xin", "" ] ]
Black hole shadow and gravitational lensing play important roles in testing gravitational theories in the strong field regime. As the first-order modifications from quantum gravity, the nonlocality can be manifested by black hole shadow and gravitational lensing. For example, the cut-off parameter introduced by nonlocality will affect the shape and size of the black hole shadow, and also affect the deflection angle of light rays. In this paper, we mainly investigate the effects of the nonlocality on the black hole shadow and the gravitational lensing for two types of rotating black holes in nonlocal gravity. It is found that the size of the black hole shadow decreases with the cut-off parameter since the nonlocality weakens the gravitational constant, and the shape of the shadow gets more deformed with the increase of the cut-off parameter. However, if the rotation parameter is small, the shape of the shadow is almost a circle even though the cut-off parameter approaches its maximum. The energy emission rate in both models is also studied. The results show that there is a peak for each curve and the peak decreases and shifts to the low frequency with the increase of the cut-off parameter. Besides, we also explore the shadow of both types of black holes surrounded by a nonmagnetized pressureless plasma which satisfies the separability condition. It is found that the plasma has a frequency-dependent dispersive effect on the size and shape of the black hole shadow. For the gravitational lensing, we find that the cut-off parameter of model A makes a positive contribution to the deflection angle, which can be compared with the contribution of the rotation parameter, while the cut-off parameter of model B makes a negative contribution which can be ignored. These results may be helpful for probing nonlocal gravity in future observations.
gr-qc/0411143
Miguel S\'anchez
Miguel S\'anchez
Causal hierarchy of spacetimes, temporal functions and smoothness of Geroch's splitting. A revision
Contribution to Proc. XIII Escola de Geometria Diferencial, Sao Paulo, 2004. 21 pages, 3 figures, Latex. Minor linguistic changes, to appear in Matem\'atica Contemporanea
Matematica Contemporanea, Vol 29, 127-155 (2005)
null
null
gr-qc
null
After the heroic epoch of Causality Theory, problems concerning the smoothability of time functions and Cauchy hypersurfaces remained as unanswered folk questions. Just recently solved, our aim is to discuss the state of the art on this topic, including self-contained proofs for questions on causally continuous, stably causal and globally hyperbolic spacetimes.
[ { "created": "Mon, 29 Nov 2004 19:55:29 GMT", "version": "v1" }, { "created": "Tue, 15 Feb 2005 17:05:27 GMT", "version": "v2" } ]
2023-04-21
[ [ "Sánchez", "Miguel", "" ] ]
After the heroic epoch of Causality Theory, problems concerning the smoothability of time functions and Cauchy hypersurfaces remained as unanswered folk questions. Just recently solved, our aim is to discuss the state of the art on this topic, including self-contained proofs for questions on causally continuous, stably causal and globally hyperbolic spacetimes.
1606.03115
Alma Rosa Mendez Rodriguez
A. R. Mendez, A. L. Garciia-Perciante and A. Sandoval-Villalbazo
On the role of dissipation in structure formation for dilute relativistic gases: the static background case
null
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A correction to the Jeans stability criterion due to heat conduction is established for the case of high temperature gases. This effect is only relevant for relativistic fluids and includes an additional term due to a density gradient driven heat flux. The result is obtained by thoroughly analyzing the exponentially growing modes present in the dynamics of density fluctuations in the linearized relativistic Navier-Stokes regime. The corrections to the corresponding Jeans mass and wavenumber are explicitly obtained and are compared to the non-relativistic and non-dissipative values using the transport coefficients obtained in the BGK approximation.
[ { "created": "Thu, 9 Jun 2016 20:47:16 GMT", "version": "v1" }, { "created": "Wed, 15 Jun 2016 17:50:53 GMT", "version": "v2" } ]
2016-06-16
[ [ "Mendez", "A. R.", "" ], [ "Garciia-Perciante", "A. L.", "" ], [ "Sandoval-Villalbazo", "A.", "" ] ]
A correction to the Jeans stability criterion due to heat conduction is established for the case of high temperature gases. This effect is only relevant for relativistic fluids and includes an additional term due to a density gradient driven heat flux. The result is obtained by thoroughly analyzing the exponentially growing modes present in the dynamics of density fluctuations in the linearized relativistic Navier-Stokes regime. The corrections to the corresponding Jeans mass and wavenumber are explicitly obtained and are compared to the non-relativistic and non-dissipative values using the transport coefficients obtained in the BGK approximation.
1911.09689
Gabriele Franciolini
V. De Luca, G. Franciolini, A. Kehagias, A. Riotto
On the Gauge Invariance of Cosmological Gravitational Waves
26 pages, 3 figures, version accepted by JCAP
null
10.1088/1475-7516/2020/03/014
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The issue of the gauge invariance of gravitational waves arises if they are produced in the early universe at second-order in perturbation theory. We address it by dividing the discussion about the gauge invariance in three parts: the production of gravitational waves, their propagation in the real universe, and their measurement.
[ { "created": "Thu, 21 Nov 2019 19:00:09 GMT", "version": "v1" }, { "created": "Tue, 3 Dec 2019 18:40:15 GMT", "version": "v2" }, { "created": "Mon, 9 Mar 2020 15:45:28 GMT", "version": "v3" } ]
2020-03-18
[ [ "De Luca", "V.", "" ], [ "Franciolini", "G.", "" ], [ "Kehagias", "A.", "" ], [ "Riotto", "A.", "" ] ]
The issue of the gauge invariance of gravitational waves arises if they are produced in the early universe at second-order in perturbation theory. We address it by dividing the discussion about the gauge invariance in three parts: the production of gravitational waves, their propagation in the real universe, and their measurement.
1001.1838
Catherine Meusburger
C. Meusburger
Spacetime geometry in (2+1)-gravity via measurements with returning lightrays
Talk given at the XXV Max Born Symposium: The Planck Scale (Wroclaw, June 29-July 3 2009) 10 pages, 4 eps figures
AIP Conf. Proc. 1196 (2009) 181-189
null
null
gr-qc math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider an observer in a (2+1)-spacetime without matter and cosmological constant who measures spacetime geometry by emitting lightrays which return to him at a later time. We investigate several quantities associated with such lightrays: the return time, the directions into which light needs to be emitted to return and the frequency shift between the lightray at its emission and its return. We derive explicit expressions for these quantities as functions on the reduced phase space and show how they allow the observer to reconstruct the full geometry of the spacetime in finite eigentime. We comment on conceptual issues. In particular, we clarify the relation between these quantities and Dirac observables and show that Wilson loops arise naturally in these quantities.
[ { "created": "Tue, 12 Jan 2010 10:41:19 GMT", "version": "v1" } ]
2010-01-24
[ [ "Meusburger", "C.", "" ] ]
We consider an observer in a (2+1)-spacetime without matter and cosmological constant who measures spacetime geometry by emitting lightrays which return to him at a later time. We investigate several quantities associated with such lightrays: the return time, the directions into which light needs to be emitted to return and the frequency shift between the lightray at its emission and its return. We derive explicit expressions for these quantities as functions on the reduced phase space and show how they allow the observer to reconstruct the full geometry of the spacetime in finite eigentime. We comment on conceptual issues. In particular, we clarify the relation between these quantities and Dirac observables and show that Wilson loops arise naturally in these quantities.
1605.06463
Marek Nowakowski
P. Bargue\~no, S. Bravo Medina, M. Nowakowski, D. Batic
Quantum Mechanical Corrections to the Schwarzschild Black Hole Metric
14 pages Latex, enlarged version as compared to the published one
Eur. Phys. Lett. 117, (2017) 60006
10.1209/0295-5075/117/60006
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Motivated by quantum mechanical corrections to the Newtonian potential, which can be translated into an $\hbar$-correction to the $g_{00}$ component of the Schwarzschild metric, we construct a quantum mechanically corrected metric assuming $-g_{00}=g^{rr}$. We show how the Bekenstein black hole entropy $S$ receives its logarithmic contribution provided the quantum mechanical corrections to the metric are negative. In this case the standard horizon at the Schwarzschild radius $r_S$ increases by small terms proportional to $\hbar$ and a remnant of the order of Planck mass emerges. We contrast these results with a positive correction to the metric which, apart from a corrected Schwarzschild horizon, leads to a new purely quantum mechanical horizon.
[ { "created": "Fri, 20 May 2016 18:34:25 GMT", "version": "v1" }, { "created": "Wed, 31 May 2017 21:14:00 GMT", "version": "v2" } ]
2017-06-02
[ [ "Bargueño", "P.", "" ], [ "Medina", "S. Bravo", "" ], [ "Nowakowski", "M.", "" ], [ "Batic", "D.", "" ] ]
Motivated by quantum mechanical corrections to the Newtonian potential, which can be translated into an $\hbar$-correction to the $g_{00}$ component of the Schwarzschild metric, we construct a quantum mechanically corrected metric assuming $-g_{00}=g^{rr}$. We show how the Bekenstein black hole entropy $S$ receives its logarithmic contribution provided the quantum mechanical corrections to the metric are negative. In this case the standard horizon at the Schwarzschild radius $r_S$ increases by small terms proportional to $\hbar$ and a remnant of the order of Planck mass emerges. We contrast these results with a positive correction to the metric which, apart from a corrected Schwarzschild horizon, leads to a new purely quantum mechanical horizon.
1311.2409
Alicia M. Sintes
The LIGO Scientific Collaboration, The Virgo Collaboration: J. Aasi, J. Abadie, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T. Accadia, F. Acernese, C. Adams, T. Adams, R. X. Adhikari, C. Affeldt, M. Agathos, N. Aggarwal, O. D. Aguiar, P. Ajith, B. Allen, A. Allocca, E. Amador Ceron, D. Amariutei, R. A. Anderson, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. Areeda, S. Ast, S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert, L. Austin, B. E. Aylott, S. Babak, P. T. Baker, G. Ballardin, S. W. Ballmer, J. C. Barayoga, D. Barker, S. H. Barnum, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, M. A. Barton, I. Bartos, R. Bassiri, A. Basti, J. Batch, J. Bauchrowitz, Th. S. Bauer, M. Bebronne, B. Behnke, M. Bejger, M.G. Beker, A. S. Bell, C. Bell, I. Belopolski, G. Bergmann, J. M. Berliner, D. Bersanetti, A. Bertolini, D. Bessis, J. Betzwieser, P. T. Beyersdorf, T. Bhadbhade, I. A. Bilenko, G. Billingsley, J. Birch, M. Bitossi, M. A. Bizouard, E. Black, J. K. Blackburn, L. Blackburn, D. Blair, M. Blom, O. Bock, T. P. Bodiya, M. Boer, C. Bogan, C. Bond, F. Bondu, L. Bonelli, R. Bonnand, R. Bork, M. Born, V. Boschi, S. Bose, L. Bosi, J. Bowers, C. Bradaschia, P. R. Brady, V. B. Braginsky, M. Branchesi, C. A. Brannen, J. E. Brau, J. Breyer, T. Briant, D. O. Bridges, A. Brillet, M. Brinkmann, V. Brisson, M. Britzger, A. F. Brooks, D. A. Brown, D. D. Brown, F. Br\"uckner, T. Bulik, H. J. Bulten, A. Buonanno, D. Buskulic, C. Buy, R. L. Byer, L. Cadonati, G. Cagnoli, J. Calder\'on Bustillo, E. Calloni, J. B. Camp, P. Campsie, K. C. Cannon, B. Canuel, J. Cao, C. D. Capano, F. Carbognani, L. Carbone, S. Caride, A. Castiglia, S. Caudill, M. Cavaglia, F. Cavalier, R. Cavalieri, G. Cella, C. Cepeda, E. Cesarini, R. Chakraborty, T. Chalermsongsak, S. Chao, P. Charlton, E. Chassande-Mottin, X. Chen, Y. Chen, A. Chincarini, A. Chiummo, H. S. Cho, J. Chow, N. Christensen, Q. Chu, S. S. Y. Chua, S. Chung, G. Ciani, F. Clara, D. E. Clark, J. A. Clark, F. Cleva, E. Coccia, P.-F. Cohadon, A. Colla, M. Colombini, M. Constancio Jr., A. Conte, R. Conte, D. Cook, T. R. Corbitt, M. Cordier, N. Cornish, A. Corsi, C. A. Costa, M. W. Coughlin, J.-P. Coulon, S. Countryman, P. Couvares, D. M. Coward, M. Cowart, D. C. Coyne, K. Craig, J. D. E. Creighton, T. D. Creighton, S. G. Crowder, A. Cumming, L. Cunningham, E. Cuoco, K. Dahl, T. Dal Canton, M. Damjanic, S. L. Danilishin, S. D'Antonio, K. Danzmann, V. Dattilo, B. Daudert, H. Daveloza, M. Davier, G. S. Davies, E. J. Daw, R. Day, T. Dayanga, G. Debreczeni, J. Degallaix, E. Deleeuw, S. Del\'eglise, W. Del Pozzo, T. Denker, T. Dent, H. Dereli, V. Dergachev, R. T. DeRosa, R. De Rosa, R. DeSalvo, S. Dhurandhar, M. D\'iaz, A. Dietz, L. Di Fiore, A. Di Lieto, I. Di Palma, A. Di Virgilio, K. Dmitry, F. Donovan, K. L. Dooley, S. Doravari, M. Drago, R. W. P. Drever, J. C. Driggers, Z. Du, J. C. Dumas, S. Dwyer, T. Eberle, M. Edwards, A. Effler, P. Ehrens, J. Eichholz, S. S. Eikenberry, G. Endroczi, R. Essick, T. Etzel, K. Evans, M. Evans, T. Evans, M. Factourovich, V. Fafone, S. Fairhurst, Q. Fang, S. Farinon, B. Farr, W. Farr, M. Favata, D. Fazi, H. Fehrmann, D. Feldbaum, I. Ferrante, F. Ferrini, F. Fidecaro, L. S. Finn, I. Fiori, R. Fisher, R. Flaminio, E. Foley, S. Foley, E. Forsi, N. Fotopoulos, J. D. Fournier, S. Franco, S. Frasca, F. Frasconi, M. Frede, M. Frei, Z. Frei, A. Freise, R. Frey, T. T. Fricke, P. Fritschel, V. V. Frolov, M.-K. Fujimoto, P. Fulda, M. Fyffe, J. Gair, L. Gammaitoni, J. Garcia, F. Garufi, N. Gehrels, G. Gemme, E. Genin, A. Gennai, L. Gergely, S. Ghosh, J. A. Giaime, S. Giampanis, K. D. Giardina, A. Giazotto, S. Gil-Casanova, C. Gill, J. Gleason, E. Goetz, R. Goetz, L. Gondan, G. Gonz\'alez, N. Gordon, M. L. Gorodetsky, S. Gossan, S. Gossler, R. Gouaty, C. Graef, P. B. Graff, M. Granata, A. Grant, S. Gras, C. Gray, R. J. S. Greenhalgh, A. M. Gretarsson, C. Griffo, P. Groot, H. Grote, K. Grover, S. Grunewald, G. M. Guidi, C. Guido, K. E. Gushwa, E. K. Gustafson, R. Gustafson, B. Hall, E. Hall, D. Hammer, G. Hammond, M. Hanke, J. Hanks, C. Hanna, J. Hanson, J. Harms, G. M. Harry, I. W. Harry, E. D. Harstad, M. T. Hartman, K. Haughian, K. Hayama, J. Heefner, A. Heidmann, M. Heintze, H. Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, A. W. Heptonstall, M. Heurs, S. Hild, D. Hoak, K. A. Hodge, K. Holt, T. Hong, S. Hooper, T. Horrom, D. J. Hosken, J. Hough, E. J. Howell, Y. Hu, Z. Hua, V. Huang, E. A. Huerta, B. Hughey, S. Husa, S. H. Huttner, M. Huynh, T. Huynh-Dinh, J. Iafrate, D. R. Ingram, R. Inta, T. Isogai, A. Ivanov, B. R. Iyer, K. Izumi, M. Jacobson, E. James, H. Jang, Y. J. Jang, P. Jaranowski, F. Jim\'enez-Forteza, W. W. Johnson, D. Jones, D. I. Jones, R. Jones, R.J.G. Jonker, L. Ju, Haris K, P. Kalmus, V. Kalogera, S. Kandhasamy, G. Kang, J. B. Kanner, M. Kasprzack, R. Kasturi, E. Katsavounidis, W. Katzman, H. Kaufer, K. Kaufman, K. Kawabe, S. Kawamura, F. Kawazoe, F. K\'ef\'elian, D. Keitel, D. B. Kelley, W. Kells, D. G. Keppel, A. Khalaidovski, F. Y. Khalili, E. A. Khazanov, B. K. Kim, C. Kim, K. Kim, N. Kim, W. Kim, Y. M. Kim, E. J. King, P. J. King, D. L. Kinzel, J. S. Kissel, S. Klimenko, J. Kline, S. Koehlenbeck, K. Kokeyama, V. Kondrashov, S. Koranda, W. Z. Korth, I. Kowalska, D. Kozak, A. Kremin, V. Kringel, B. Krishnan, A. Kr\'olak, C. Kucharczyk, S. Kudla, G. Kuehn, A. Kumar, P. Kumar, R. Kumar, R. Kurdyumov, P. Kwee, M. Landry, B. Lantz, S. Larson, P. D. Lasky, C. Lawrie, P. Leaci, E. O. Lebigot, C. H. Lee, H. K. Lee, H. M. Lee, J. Lee, J. Lee, M. Leonardi, J. R. Leong, A. Le Roux, N. Leroy, N. Letendre, B. Levine, J. B. Lewis, V. Lhuillier, T. G. F. Li, A. C. Lin, T. B. Littenberg, V. Litvine, F. Liu, H. Liu, Y. Liu, Z. Liu, D. Lloyd, N. A. Lockerbie, V. Lockett, D. Lodhia, K. Loew, J. Logue, A. L. Lombardi, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. Lough, J. Luan, M. J. Lubinski, H. L\"uck, A. P. Lundgren, J. Macarthur, E. Macdonald, B. Machenschalk, M. MacInnis, D. M. Macleod, F. Magana-Sandoval, M. Mageswaran, K. Mailand, E. Majorana, I. Maksimovic, V. Malvezzi, N. Man, G. M. Manca, I. Mandel, V. Mandic, V. Mangano, M. Mantovani, F. Marchesoni, F. Marion, S. M\'arka, Z. M\'arka, A. Markosyan, E. Maros, J. Marque, F. Martelli, I. W. Martin, R. M. Martin, L. Martinelli, D. Martynov, J. N. Marx, K. Mason, A. Masserot, T. J. Massinger, F. Matichard, L. Matone, R. A. Matzner, N. Mavalvala, G. May, N. Mazumder, G. Mazzolo, R. McCarthy, D. E. McClelland, S. C. McGuire, G. McIntyre, J. McIver, D. Meacher, G. D. Meadors, M. Mehmet, J. Meidam, T. Meier, A. Melatos, G. Mendell, R. A. Mercer, S. Meshkov, C. Messenger, M. S. Meyer, H. Miao, C. Michel, E. E. Mikhailov, L. Milano, J. Miller, Y. Minenkov, C. M. F. Mingarelli, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, B. Moe, M. Mohan, S. R. P. Mohapatra, F. Mokler, D. Moraru, G. Moreno, N. Morgado, T. Mori, S. R. Morriss, K. Mossavi, B. Mours, C. M. Mow-Lowry, C. L. Mueller, G. Mueller, S. 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Zhao, H. Zhu, X. J. Zhu, N. Zotov, M. E. Zucker and J. Zweizig
Application of a Hough search for continuous gravitational waves on data from the 5th LIGO science run
Accepted in Classical and Quantum Gravity. Science summary of results available at http://www.ligo.org/science/Publication-S5CWHough/index.php
null
10.1088/0264-9381/31/8/085014
LIGO Document P1300071
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We report on an all-sky search for periodic gravitational waves in the frequency range $\mathrm{50-1000 Hz}$ with the first derivative of frequency in the range $-8.9 \times 10^{-10}$ Hz/s to zero in two years of data collected during LIGO's fifth science run. Our results employ a Hough transform technique, introducing a $\chi^2$ test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strain sensitivity with compute cycles per data sample compared to previously published searches. Since our search yields no surviving candidates, we present results taking the form of frequency dependent, 95$%$ confidence upper limits on the strain amplitude $h_0$. The most stringent upper limit from year 1 is $1.0\times 10^{-24}$ in the $\mathrm{158.00-158.25 Hz}$ band. In year 2, the most stringent upper limit is $\mathrm{8.9\times10^{-25}}$ in the $\mathrm{146.50-146.75 Hz}$ band. This improved detection pipeline, which is computationally efficient by at least two orders of magnitude better than our flagship Einstein$@$Home search, will be important for "quick-look" searches in the Advanced LIGO and Virgo detector era.
[ { "created": "Mon, 11 Nov 2013 10:32:54 GMT", "version": "v1" }, { "created": "Wed, 27 Nov 2013 11:03:27 GMT", "version": "v2" }, { "created": "Mon, 17 Mar 2014 10:54:38 GMT", "version": "v3" } ]
2015-06-17
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M.", "" ], [ "Seifert", "F.", "" ], [ "Sellers", "D.", "" ], [ "Sengupta", "A. S.", "" ], [ "Sentenac", "D.", "" ], [ "Sequino", "V.", "" ], [ "Sergeev", "A.", "" ], [ "Shaddock", "D.", "" ], [ "Shah", "S.", "" ], [ "Shahriar", "M. S.", "" ], [ "Shaltev", "M.", "" ], [ "Shapiro", "B.", "" ], [ "Shawhan", "P.", "" ], [ "Shoemaker", "D. H.", "" ], [ "Sidery", "T. L.", "" ], [ "Siellez", "K.", "" ], [ "Siemens", "X.", "" ], [ "Sigg", "D.", "" ], [ "Simakov", "D.", "" ], [ "Singer", "A.", "" ], [ "Singer", "L.", "" ], [ "Sintes", "A. M.", "" ], [ "Skelton", "G. R.", "" ], [ "Slagmolen", "B. J. J.", "" ], [ "Slutsky", "J.", "" ], [ "Smith", "J. R.", "" ], [ "Smith", "M. R.", "" ], [ "Smith", "R. J. E.", "" ], [ "Smith-Lefebvre", "N. D.", "" ], [ "Soden", "K.", "" ], [ "Son", "E. J.", "" ], [ "Sorazu", "B.", "" ], [ "Souradeep", "T.", "" ], [ "Sperandio", "L.", "" ], [ "Staley", "A.", "" ], [ "Steinert", "E.", "" ], [ "Steinlechner", "J.", "" ], [ "Steinlechner", "S.", "" ], [ "Steplewski", "S.", "" ], [ "Stevens", "D.", "" ], [ "Stochino", "A.", "" ], [ "Stone", "R.", "" ], [ "Strain", "K. A.", "" ], [ "Straniero", "N.", "" ], [ "Strigin", "S.", "" ], [ "Stroeer", "A. S.", "" ], [ "Sturani", "R.", "" ], [ "Stuver", "A. L.", "" ], [ "Summerscales", "T. Z.", "" ], [ "Susmithan", "S.", "" ], [ "Sutton", "P. J.", "" ], [ "Swinkels", "B.", "" ], [ "Szeifert", "G.", "" ], [ "Tacca", "M.", "" ], [ "Talukder", "D.", "" ], [ "Tang", "L.", "" ], [ "Tanner", "D. B.", "" ], [ "Tarabrin", "S. P.", "" ], [ "Taylor", "R.", "" ], [ "ter Braack", "A. P. M.", "" ], [ "Thirugnanasambandam", "M. P.", "" ], [ "Thomas", "M.", "" ], [ "Thomas", "P.", "" ], [ "Thorne", "K. A.", "" ], [ "Thorne", "K. S.", "" ], [ "Thrane", "E.", "" ], [ "Tiwari", "V.", "" ], [ "Tokmakov", "K. V.", "" ], [ "Tomlinson", "C.", "" ], [ "Toncelli", "A.", "" ], [ "Tonelli", "M.", "" ], [ "Torre", "O.", "" ], [ "Torres", "C. V.", "" ], [ "Torrie", "C. I.", "" ], [ "Travasso", "F.", "" ], [ "Traylor", "G.", "" ], [ "Tse", "M.", "" ], [ "Ugolini", "D.", "" ], [ "Unnikrishnan", "C. S.", "" ], [ "Vahlbruch", "H.", "" ], [ "Vajente", "G.", "" ], [ "Vallisneri", "M.", "" ], [ "Brand", "J. F. J. van den", "" ], [ "Broeck", "C. Van Den", "" ], [ "van der Putten", "S.", "" ], [ "van der Sluys", "M. V.", "" ], [ "van Heijningen", "J.", "" ], [ "van Veggel", "A. A.", "" ], [ "Vass", "S.", "" ], [ "Vasúth", "M.", "" ], [ "Vaulin", "R.", "" ], [ "Vecchio", "A.", "" ], [ "Vedovato", "G.", "" ], [ "Veitch", "J.", "" ], [ "Veitch", "P. J.", "" ], [ "Venkateswara", "K.", "" ], [ "Verkindt", "D.", "" ], [ "Verma", "S.", "" ], [ "Vetrano", "F.", "" ], [ "Viceré", "A.", "" ], [ "Vincent-Finley", "R.", "" ], [ "Vinet", "J. Y.", "" ], [ "Vitale", "S.", "" ], [ "Vlcek", "B.", "" ], [ "Vo", "T.", "" ], [ "Vocca", "H.", "" ], [ "Vorvick", "C.", "" ], [ "Vousden", "W. D.", "" ], [ "Vrinceanu", "D.", "" ], [ "Vyachanin", "S. P.", "" ], [ "Wade", "A.", "" ], [ "Wade", "L.", "" ], [ "Wade", "M.", "" ], [ "Waldman", "S. J.", "" ], [ "Walker", "M.", "" ], [ "Wallace", "L.", "" ], [ "Wan", "Y.", "" ], [ "Wang", "J.", "" ], [ "Wang", "M.", "" ], [ "Wang", "X.", "" ], [ "Wanner", "A.", "" ], [ "Ward", "R. L.", "" ], [ "Was", "M.", "" ], [ "Weaver", "B.", "" ], [ "Wei", "L. -W.", "" ], [ "Weinert", "M.", "" ], [ "Weinstein", "A. J.", "" ], [ "Weiss", "R.", "" ], [ "Welborn", "T.", "" ], [ "Wen", "L.", "" ], [ "Wessels", "P.", "" ], [ "West", "M.", "" ], [ "Westphal", "T.", "" ], [ "Wette", "K.", "" ], [ "Whelan", "J. T.", "" ], [ "Whitcomb", "S. E.", "" ], [ "White", "D. J.", "" ], [ "Whiting", "B. F.", "" ], [ "Wibowo", "S.", "" ], [ "Wiesner", "K.", "" ], [ "Wilkinson", "C.", "" ], [ "Williams", "L.", "" ], [ "Williams", "R.", "" ], [ "Williams", "T.", "" ], [ "Willis", "J. L.", "" ], [ "Willke", "B.", "" ], [ "Wimmer", "M.", "" ], [ "Winkelmann", "L.", "" ], [ "Winkler", "W.", "" ], [ "Wipf", "C. C.", "" ], [ "Wittel", "H.", "" ], [ "Woan", "G.", "" ], [ "Worden", "J.", "" ], [ "Yablon", "J.", "" ], [ "Yakushin", "I.", "" ], [ "Yamamoto", "H.", "" ], [ "Yancey", "C. C.", "" ], [ "Yang", "H.", "" ], [ "Yeaton-Massey", "D.", "" ], [ "Yoshida", "S.", "" ], [ "Yum", "H.", "" ], [ "Yvert", "M.", "" ], [ "Zadrozny", "A.", "" ], [ "Zanolin", "M.", "" ], [ "Zendri", "J. -P.", "" ], [ "Zhang", "F.", "" ], [ "Zhang", "L.", "" ], [ "Zhao", "C.", "" ], [ "Zhu", "H.", "" ], [ "Zhu", "X. J.", "" ], [ "Zotov", "N.", "" ], [ "Zucker", "M. E.", "" ], [ "Zweizig", "J.", "" ] ]
We report on an all-sky search for periodic gravitational waves in the frequency range $\mathrm{50-1000 Hz}$ with the first derivative of frequency in the range $-8.9 \times 10^{-10}$ Hz/s to zero in two years of data collected during LIGO's fifth science run. Our results employ a Hough transform technique, introducing a $\chi^2$ test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strain sensitivity with compute cycles per data sample compared to previously published searches. Since our search yields no surviving candidates, we present results taking the form of frequency dependent, 95$%$ confidence upper limits on the strain amplitude $h_0$. The most stringent upper limit from year 1 is $1.0\times 10^{-24}$ in the $\mathrm{158.00-158.25 Hz}$ band. In year 2, the most stringent upper limit is $\mathrm{8.9\times10^{-25}}$ in the $\mathrm{146.50-146.75 Hz}$ band. This improved detection pipeline, which is computationally efficient by at least two orders of magnitude better than our flagship Einstein$@$Home search, will be important for "quick-look" searches in the Advanced LIGO and Virgo detector era.
gr-qc/0406110
Dmitri Burlankov E.
D.E. Burlankov
The Quantum Big Bang in Global Time Theory
4 pages
null
null
null
gr-qc
null
The it Global Time Theory (GTT) is the further development of the General Relativity (GR). GTT significantly differs from GR in the general physical concepts, but retains 90% of the mathematical structure and main results. The dynamics equations are derived from Lagrangian, and the Hamiltonian of gravitation is nonzero. The quantum theory of gravitation can be built on the basis of the Schroedinger equation, as for other fields. The quantum model of the Big Bang is demonstrated.
[ { "created": "Mon, 28 Jun 2004 08:32:36 GMT", "version": "v1" } ]
2007-05-23
[ [ "Burlankov", "D. E.", "" ] ]
The it Global Time Theory (GTT) is the further development of the General Relativity (GR). GTT significantly differs from GR in the general physical concepts, but retains 90% of the mathematical structure and main results. The dynamics equations are derived from Lagrangian, and the Hamiltonian of gravitation is nonzero. The quantum theory of gravitation can be built on the basis of the Schroedinger equation, as for other fields. The quantum model of the Big Bang is demonstrated.
1801.06017
Jakub Mielczarek Ph.D.
Jakub Mielczarek
Spin networks on adiabatic quantum computer
16 pages, 10 figure, comments are welcome
null
null
null
gr-qc hep-th quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The article is addressing a possibility of implementation of spin network states on adiabatic quantum computer. The discussion is focused on application of currently available technologies and analyzes a concrete example of D-Wave machine. A class of simple spin network states which can be implemented on the Chimera graph architecture of the D-Wave quantum processor is introduced. However, extension beyond the currently available quantum processor topologies is required to simulate more sophisticated spin network states, which may inspire development of new generations of adiabatic quantum computers. A possibility of simulating Loop Quantum Gravity is discussed and a method of solving a graph non-changing scalar (Hamiltonian) constraint with the use of adiabatic quantum computations is proposed.
[ { "created": "Thu, 18 Jan 2018 13:56:53 GMT", "version": "v1" } ]
2018-01-19
[ [ "Mielczarek", "Jakub", "" ] ]
The article is addressing a possibility of implementation of spin network states on adiabatic quantum computer. The discussion is focused on application of currently available technologies and analyzes a concrete example of D-Wave machine. A class of simple spin network states which can be implemented on the Chimera graph architecture of the D-Wave quantum processor is introduced. However, extension beyond the currently available quantum processor topologies is required to simulate more sophisticated spin network states, which may inspire development of new generations of adiabatic quantum computers. A possibility of simulating Loop Quantum Gravity is discussed and a method of solving a graph non-changing scalar (Hamiltonian) constraint with the use of adiabatic quantum computations is proposed.
1907.10329
Arianna Renzini
Arianna Renzini and Carlo Contaldi
Improved limits on a stochastic gravitational-wave background and its anisotropies from Advanced LIGO O1 and O2 runs
9 pages, 8 figures
Phys. Rev. D 100, 063527 (2019)
10.1103/PhysRevD.100.063527
null
gr-qc astro-ph.CO astro-ph.IM
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We integrate the entire, publicly available, Advanced LIGO (ALIGO) data set to obtain maximum-likelihood constraint maps of the Stochastic Gravitational-Wave Background (SGWB). From these we derive limits on the energy density of the stochastic background $\Omega_{\rm GW}$, and its anisotropy. We find 95% confident limits $\Omega_{\rm GW} < 5.2\times 10^{-8}$ at $50$ Hz for a spectral index $\alpha=2/3$ consistent with a stochastic background due to inspiral events and $\Omega_{\rm GW} < 3.2\times 10^{-7}$ for a scale (frequency) invariant spectrum. We also report upper limits on the angular power spectra $C_\ell$ for three broadband integrations of the data. Finally we present an estimate where we integrate the data into ten separate spectral bins as a first attempt to carry out a model-independent estimate the SGWB and its anisotropies.
[ { "created": "Wed, 24 Jul 2019 09:49:26 GMT", "version": "v1" } ]
2019-09-25
[ [ "Renzini", "Arianna", "" ], [ "Contaldi", "Carlo", "" ] ]
We integrate the entire, publicly available, Advanced LIGO (ALIGO) data set to obtain maximum-likelihood constraint maps of the Stochastic Gravitational-Wave Background (SGWB). From these we derive limits on the energy density of the stochastic background $\Omega_{\rm GW}$, and its anisotropy. We find 95% confident limits $\Omega_{\rm GW} < 5.2\times 10^{-8}$ at $50$ Hz for a spectral index $\alpha=2/3$ consistent with a stochastic background due to inspiral events and $\Omega_{\rm GW} < 3.2\times 10^{-7}$ for a scale (frequency) invariant spectrum. We also report upper limits on the angular power spectra $C_\ell$ for three broadband integrations of the data. Finally we present an estimate where we integrate the data into ten separate spectral bins as a first attempt to carry out a model-independent estimate the SGWB and its anisotropies.
2304.14769
Masahiko Taniguchi
Tomohiro Inagaki, Hiroki Sakamoto, Masahiko Taniguchi
Robustness of predicted CMB fluctuations in Cartan $F(R)$ gravity
14pages, 4figures
JCAP 09 (2023) 014
10.1088/1475-7516/2023/09/014
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The cosmology of the $F(R)$ gravity rebuilding by the Cartan formalism is investigated. This is called Cartan $F(R)$ gravity. The well-known $F(R)$ gravity has been introduced to extend the standard cosmology, e.g. to explain the cosmological accelerated expansion as the inflation. Cartan $F(R)$ gravity is based on the Riemann-Cartan geometry. The curvature $R$ can separate to two parts, one is derived from the Levi-Civita connection and the other from the torsion. Assuming the matter-independent spin connection, we have successfully rewritten the action of Cartan $F(R)$ gravity into the Einstein-Hilbert action and a scalar field with canonical kinetic and potential terms without any conformal transformations. This feature simplifies building and analysis of new model of inflation. In this paper, we study two models, the power-law model and logarithmic model, and evaluate fluctuations in the cosmological microwave background (CMB) radiation. We found the robustness of CMB fluctuation by the analytical computation and confirm this feature by the numerical calculation.
[ { "created": "Fri, 28 Apr 2023 11:28:13 GMT", "version": "v1" }, { "created": "Fri, 22 Sep 2023 13:54:07 GMT", "version": "v2" } ]
2023-09-25
[ [ "Inagaki", "Tomohiro", "" ], [ "Sakamoto", "Hiroki", "" ], [ "Taniguchi", "Masahiko", "" ] ]
The cosmology of the $F(R)$ gravity rebuilding by the Cartan formalism is investigated. This is called Cartan $F(R)$ gravity. The well-known $F(R)$ gravity has been introduced to extend the standard cosmology, e.g. to explain the cosmological accelerated expansion as the inflation. Cartan $F(R)$ gravity is based on the Riemann-Cartan geometry. The curvature $R$ can separate to two parts, one is derived from the Levi-Civita connection and the other from the torsion. Assuming the matter-independent spin connection, we have successfully rewritten the action of Cartan $F(R)$ gravity into the Einstein-Hilbert action and a scalar field with canonical kinetic and potential terms without any conformal transformations. This feature simplifies building and analysis of new model of inflation. In this paper, we study two models, the power-law model and logarithmic model, and evaluate fluctuations in the cosmological microwave background (CMB) radiation. We found the robustness of CMB fluctuation by the analytical computation and confirm this feature by the numerical calculation.
gr-qc/9910036
Fran DeAquino
Fran De Aquino (Maranhao State University, Brazil)
Theory of Everything
arXiv admin note: substantial text overlap with arXiv:physics/9904018, arXiv:physics/0212033, arXiv:physics/0701091
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This is a set of 25 articles, developed starting from the Relativistic Theory of Quantum Gravity (first article). Together they form the Theory of Everything.
[ { "created": "Mon, 11 Oct 1999 22:31:57 GMT", "version": "v1" }, { "created": "Thu, 22 Aug 2013 19:27:50 GMT", "version": "v10" }, { "created": "Wed, 4 Dec 2013 10:26:08 GMT", "version": "v11" }, { "created": "Tue, 12 Oct 1999 13:34:46 GMT", "version": "v2" }, { "created": "Thu, 14 Oct 1999 01:37:41 GMT", "version": "v3" }, { "created": "Sun, 7 Nov 1999 23:12:38 GMT", "version": "v4" }, { "created": "Sun, 30 Jan 2000 14:58:19 GMT", "version": "v5" }, { "created": "Wed, 12 Apr 2000 19:13:02 GMT", "version": "v6" }, { "created": "Thu, 13 Apr 2000 13:54:48 GMT", "version": "v7" }, { "created": "Wed, 7 Jun 2000 19:28:36 GMT", "version": "v8" }, { "created": "Wed, 30 Oct 2002 19:01:56 GMT", "version": "v9" } ]
2013-12-05
[ [ "De Aquino", "Fran", "", "Maranhao State University, Brazil" ] ]
This is a set of 25 articles, developed starting from the Relativistic Theory of Quantum Gravity (first article). Together they form the Theory of Everything.
gr-qc/9308026
Hugh Luckock
R. Graham and H. Luckock
Nicolai Maps for Quantum Cosmology
17 pages, Latex, Sydney University Maths Report 93-26
Phys.Rev. D49 (1994) 2786-2791
10.1103/PhysRevD.49.2786
null
gr-qc
null
We construct Nicolai maps for $N=2$ supersymmetric extensions of minisuperspace models. It is shown that Nicolai maps exist for only a very restricted set of states. In the models considered these are the two states corresponding to the empty and the filled fermion sectors. The form of the Nicolai maps in these sectors is given explicitly, and it is shown that they have a natural stochastic interpretation. This result also suggests a probabilistic interpretation of the wave function.
[ { "created": "Tue, 24 Aug 1993 04:29:12 GMT", "version": "v1" } ]
2009-10-22
[ [ "Graham", "R.", "" ], [ "Luckock", "H.", "" ] ]
We construct Nicolai maps for $N=2$ supersymmetric extensions of minisuperspace models. It is shown that Nicolai maps exist for only a very restricted set of states. In the models considered these are the two states corresponding to the empty and the filled fermion sectors. The form of the Nicolai maps in these sectors is given explicitly, and it is shown that they have a natural stochastic interpretation. This result also suggests a probabilistic interpretation of the wave function.
gr-qc/9902058
Maria da Conceicao Bento
M. C. Bento
Maximally Symmetric Cosmological Solutions of Type II Superstrings
5 pages, Latex, no figures, talk presented at "New Worlds in Astroparticle Physics" 1998, Faro, Portugal
null
null
null
gr-qc
null
We study maximally symmetric cosmological solutions of type II supersymmetric strings in the presence of the exact, SL(2,Z)-invariant, higher-curvature corrections to the lowest order effective action. We find that, unlike the case of type IIA theories, de Sitter solutions exist, at all orders in $\alpha'$, for type IIB superstrings, when non-perturbative instanton-effects are included on the basis of SL(2,Z) invariance.
[ { "created": "Fri, 19 Feb 1999 16:17:43 GMT", "version": "v1" } ]
2007-05-23
[ [ "Bento", "M. C.", "" ] ]
We study maximally symmetric cosmological solutions of type II supersymmetric strings in the presence of the exact, SL(2,Z)-invariant, higher-curvature corrections to the lowest order effective action. We find that, unlike the case of type IIA theories, de Sitter solutions exist, at all orders in $\alpha'$, for type IIB superstrings, when non-perturbative instanton-effects are included on the basis of SL(2,Z) invariance.
1807.08771
Angelo Esposito
Angelo Esposito, Rafael Krichevsky, Alberto Nicolis
The gravitational mass carried by sound waves
6 pages
Phys. Rev. Lett. 122, 084501 (2019)
10.1103/PhysRevLett.122.084501
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We show that the commonly accepted statement that sound waves do not transport mass is only true at linear order. Using effective field theory techniques, we confirm the result found in [1] for zero-temperature superfluids, and extend it to the case of solids and ordinary fluids. We show that, in fact, sound waves do carry mass---in particular, gravitational mass. This implies that a sound wave not only is affected by gravity but also generates a tiny gravitational field, an aspect not appreciated thus far. Our findings are valid for non-relativistic media as well, and could have intriguing experimental implications.
[ { "created": "Mon, 23 Jul 2018 18:05:05 GMT", "version": "v1" }, { "created": "Sat, 2 Mar 2019 09:14:32 GMT", "version": "v2" } ]
2019-08-13
[ [ "Esposito", "Angelo", "" ], [ "Krichevsky", "Rafael", "" ], [ "Nicolis", "Alberto", "" ] ]
We show that the commonly accepted statement that sound waves do not transport mass is only true at linear order. Using effective field theory techniques, we confirm the result found in [1] for zero-temperature superfluids, and extend it to the case of solids and ordinary fluids. We show that, in fact, sound waves do carry mass---in particular, gravitational mass. This implies that a sound wave not only is affected by gravity but also generates a tiny gravitational field, an aspect not appreciated thus far. Our findings are valid for non-relativistic media as well, and could have intriguing experimental implications.
gr-qc/0304083
Dejan Stojkovic
Valeri Frolov, Martin Snajdr and Dejan Stojkovic
Interaction of a brane with a moving bulk black hole
version accepted for publication in Phys. Rev. D
Phys.Rev. D68 (2003) 044002
10.1103/PhysRevD.68.044002
null
gr-qc astro-ph hep-ph hep-th
null
We study the interaction of an n-dimensional topological defect (n-brane) described by the Nambu-Goto action with a higher-dimensional Schwarzschild black hole moving in the bulk spacetime. We derive the general form of the perturbation equations for an n-brane in the weak field approximation and solve them analytically in the most interesting cases. We specially analyze applications to brane world models. We calculate the induced geometry on the brane generated by a moving black hole. From the point of view of a brane observer, this geometry can be obtained by solving (n+1)-dimensional Einstein's equations with a non-vanishing right hand side. We calculate the effective stress-energy tensor corresponding to this `shadow-matter'. We explicitly show that there exist regions on the brane where a brane observer sees an apparent violation of energy conditions. We also study the deflection of light propagating in the region of influence of this `shadow matter'.
[ { "created": "Tue, 22 Apr 2003 17:34:45 GMT", "version": "v1" }, { "created": "Mon, 16 Jun 2003 16:25:04 GMT", "version": "v2" } ]
2009-11-10
[ [ "Frolov", "Valeri", "" ], [ "Snajdr", "Martin", "" ], [ "Stojkovic", "Dejan", "" ] ]
We study the interaction of an n-dimensional topological defect (n-brane) described by the Nambu-Goto action with a higher-dimensional Schwarzschild black hole moving in the bulk spacetime. We derive the general form of the perturbation equations for an n-brane in the weak field approximation and solve them analytically in the most interesting cases. We specially analyze applications to brane world models. We calculate the induced geometry on the brane generated by a moving black hole. From the point of view of a brane observer, this geometry can be obtained by solving (n+1)-dimensional Einstein's equations with a non-vanishing right hand side. We calculate the effective stress-energy tensor corresponding to this `shadow-matter'. We explicitly show that there exist regions on the brane where a brane observer sees an apparent violation of energy conditions. We also study the deflection of light propagating in the region of influence of this `shadow matter'.
1411.1963
Frank L\"offler
Frank L\"offler and Roberto De Pietri and Alessandra Feo and Luca Franci and Francesco Maione
Stiffness effects on the dynamics of the bar-mode instability of Neutron Stars in full General Relativity
12 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1403.8066
Phys. Rev. D 91, 064057 (2015)
10.1103/PhysRevD.91.064057
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present results on the effect of the stiffness of the equation of state on the dynamical bar-mode instability in rapidly rotating polytropic models of neutron stars in full General Relativity. We determine the change in the threshold for the emergence of the instability for a range of the adiabatic $\Gamma$ index from 2.0 to 3.0, including two values chosen to mimic more realistic equations of state at high densities.
[ { "created": "Fri, 7 Nov 2014 16:27:22 GMT", "version": "v1" } ]
2015-04-01
[ [ "Löffler", "Frank", "" ], [ "De Pietri", "Roberto", "" ], [ "Feo", "Alessandra", "" ], [ "Franci", "Luca", "" ], [ "Maione", "Francesco", "" ] ]
We present results on the effect of the stiffness of the equation of state on the dynamical bar-mode instability in rapidly rotating polytropic models of neutron stars in full General Relativity. We determine the change in the threshold for the emergence of the instability for a range of the adiabatic $\Gamma$ index from 2.0 to 3.0, including two values chosen to mimic more realistic equations of state at high densities.
1111.3415
Sergey Sushkov
Sergey Sushkov, Roman Korolev
Scalar wormholes with nonminimal derivative coupling
17 pages, 8 figures
null
10.1088/0264-9381/29/8/085008
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider static spherically symmetric wormhole configurations in a gravitational theory of a scalar field with a potential $V(\phi)$ and nonminimal derivative coupling to the curvature describing by the term $(\epsilon g_{\mu\nu} + \kappa G_{\mu\nu}) \phi^{,\mu}\phi^{,\nu}$ in the action. We show that the flare-out conditions providing the geometry of a wormhole throat could fulfilled both if $\epsilon=-1$ (phantom scalar) and $\epsilon=+1$ (ordinary scalar). Supposing additionally a traversability, we construct numerical solutions describing traversable wormholes in the model with arbitrary $\kappa$, $\epsilon=-1$ and $V(\phi)=0$ (no potential). The traversability assumes that the wormhole possesses two asymptotically flat regions with corresponding Schwarzschild masses. We find that asymptotical masses of a wormhole with nonminimal derivative coupling could be positive and/or negative depending on $\kappa$. In particular, both masses are positive only provided $\kappa<\kappa_1\le0$, otherwise one or both wormhole masses are negative. In conclusion, we give qualitative arguments that a wormhole configuration with positive masses could be stable.
[ { "created": "Tue, 15 Nov 2011 02:45:36 GMT", "version": "v1" } ]
2015-06-03
[ [ "Sushkov", "Sergey", "" ], [ "Korolev", "Roman", "" ] ]
We consider static spherically symmetric wormhole configurations in a gravitational theory of a scalar field with a potential $V(\phi)$ and nonminimal derivative coupling to the curvature describing by the term $(\epsilon g_{\mu\nu} + \kappa G_{\mu\nu}) \phi^{,\mu}\phi^{,\nu}$ in the action. We show that the flare-out conditions providing the geometry of a wormhole throat could fulfilled both if $\epsilon=-1$ (phantom scalar) and $\epsilon=+1$ (ordinary scalar). Supposing additionally a traversability, we construct numerical solutions describing traversable wormholes in the model with arbitrary $\kappa$, $\epsilon=-1$ and $V(\phi)=0$ (no potential). The traversability assumes that the wormhole possesses two asymptotically flat regions with corresponding Schwarzschild masses. We find that asymptotical masses of a wormhole with nonminimal derivative coupling could be positive and/or negative depending on $\kappa$. In particular, both masses are positive only provided $\kappa<\kappa_1\le0$, otherwise one or both wormhole masses are negative. In conclusion, we give qualitative arguments that a wormhole configuration with positive masses could be stable.
2104.00988
Mark Robert Baker
Mark Robert Baker
A connection between linearized Gauss-Bonnet gravity and classical electrodynamics II: Complete dual formulation
26 pages
International Journal of Modern Physics D, Vol. 30, No. 04, 2150030 (2021)
10.1142/S0218271821500309
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In a recent publication a procedure was developed which can be used to derive completely gauge invariant models from general Lagrangian densities with $N$ order of derivatives and $M$ rank of tensor potential. This procedure was then used to show that unique models follow for each order, namely classical electrodynamics for $N = M = 1$ and linearized Gauss-Bonnet gravity for $N = M = 2$. In this article, the nature of the connection between these two well explored physical models is further investigated by means of an additional common property; a complete dual formulation. First we give a review of Gauss-Bonnet gravity and the dual formulation of classical electrodynamics. The dual formulation of linearized Gauss-Bonnet gravity is then developed. It is shown that the dual formulation of linearized Gauss-Bonnet gravity is analogous to the homogenous half of Maxwell's theory; both have equations of motion corresponding to the (second) Bianchi identity, built from the dual form of their respective field strength tensors. In order to have a dually symmetric counterpart analogous to the non-homogenous half of Maxwell's theory, the first invariant derived from the procedure in $N = M = 2$ can be introduced. The complete gauge invariance of a model with respect to Noether's first theorem, and not just the equation of motion, is a necessary condition for this dual formulation. We show that this result can be generalized to the higher spin gauge theories, where the spin-$n$ curvature tensors for all $N = M = n$ are the field strength tensors for each $n$. These completely gauge invariant models correspond to the Maxwell-like higher spin gauge theories whose equations of motion have been well explored in the literature.
[ { "created": "Fri, 2 Apr 2021 11:15:01 GMT", "version": "v1" } ]
2021-04-05
[ [ "Baker", "Mark Robert", "" ] ]
In a recent publication a procedure was developed which can be used to derive completely gauge invariant models from general Lagrangian densities with $N$ order of derivatives and $M$ rank of tensor potential. This procedure was then used to show that unique models follow for each order, namely classical electrodynamics for $N = M = 1$ and linearized Gauss-Bonnet gravity for $N = M = 2$. In this article, the nature of the connection between these two well explored physical models is further investigated by means of an additional common property; a complete dual formulation. First we give a review of Gauss-Bonnet gravity and the dual formulation of classical electrodynamics. The dual formulation of linearized Gauss-Bonnet gravity is then developed. It is shown that the dual formulation of linearized Gauss-Bonnet gravity is analogous to the homogenous half of Maxwell's theory; both have equations of motion corresponding to the (second) Bianchi identity, built from the dual form of their respective field strength tensors. In order to have a dually symmetric counterpart analogous to the non-homogenous half of Maxwell's theory, the first invariant derived from the procedure in $N = M = 2$ can be introduced. The complete gauge invariance of a model with respect to Noether's first theorem, and not just the equation of motion, is a necessary condition for this dual formulation. We show that this result can be generalized to the higher spin gauge theories, where the spin-$n$ curvature tensors for all $N = M = n$ are the field strength tensors for each $n$. These completely gauge invariant models correspond to the Maxwell-like higher spin gauge theories whose equations of motion have been well explored in the literature.
1906.03116
Lior M. Burko
Lior M. Burko, Gaurav Khanna, and Subir Sabharwal
(Transient) Scalar Hair for (Nearly) Extreme Black Holes
5 pages, 8 figures
Phys. Rev. Research 1, 033106 (2019)
10.1103/PhysRevResearch.1.033106
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
It has been shown recently that extreme Reissner-Nordstr\"{o}m black holes perturbed by a minimally coupled, free, massless scalar field have permanent scalar hair. The hair - a conserved charge calculated at the black hole's event horizon - can be measured by a certain expression at future null infinity: the latter approaches the hair inversely in time. We generalize this newly discovered hair also for extreme Kerr black holes. We study the behavior of nearly extreme black hole hair and its measurement at future null infinity as a transient phenomenon. For nearly extreme black holes the measurement at future null infinity of the length of the newly grown hair decreases quadratically in time at intermediate times until its length becomes short and the rate at which the length shortens further slows down. Eventually, the nearly extreme BH becomes bald again like non-extreme BHs.
[ { "created": "Fri, 7 Jun 2019 14:14:25 GMT", "version": "v1" }, { "created": "Fri, 11 Oct 2019 13:16:29 GMT", "version": "v2" } ]
2019-11-19
[ [ "Burko", "Lior M.", "" ], [ "Khanna", "Gaurav", "" ], [ "Sabharwal", "Subir", "" ] ]
It has been shown recently that extreme Reissner-Nordstr\"{o}m black holes perturbed by a minimally coupled, free, massless scalar field have permanent scalar hair. The hair - a conserved charge calculated at the black hole's event horizon - can be measured by a certain expression at future null infinity: the latter approaches the hair inversely in time. We generalize this newly discovered hair also for extreme Kerr black holes. We study the behavior of nearly extreme black hole hair and its measurement at future null infinity as a transient phenomenon. For nearly extreme black holes the measurement at future null infinity of the length of the newly grown hair decreases quadratically in time at intermediate times until its length becomes short and the rate at which the length shortens further slows down. Eventually, the nearly extreme BH becomes bald again like non-extreme BHs.
gr-qc/9409004
Jorge Pullin
Jorge Pullin (Editor)
MATTERS OF GRAVITY, a newsletter for the gravity community, Number 4
Plain TeX, 24 pages
null
null
MOG-4
gr-qc
null
Table of contents Editorial. Gravity News: Report on the APS topical group in gravitation, Beverly Berger. Research briefs: Gravitational microlensing and the search for dark matter, Bohdan Paczynski. Laboratory gravity: the G mystery, Riley Newman. LIGO project update, Stan Whitcomb. Conference Reports PASCOS '94, Peter Saulson. The Vienna Meeting, P. Aichelburg, R. Beig. The Pitt binary black hole grand challenge meeting, Jeff Winicour. International symposium on experimental gravitation at Pakistan,Munawar Karim 10th Pacific coast gravity meeting, Jim Isenberg.
[ { "created": "Fri, 2 Sep 1994 21:49:36 GMT", "version": "v1" } ]
2007-05-23
[ [ "Pullin", "Jorge", "", "Editor" ] ]
Table of contents Editorial. Gravity News: Report on the APS topical group in gravitation, Beverly Berger. Research briefs: Gravitational microlensing and the search for dark matter, Bohdan Paczynski. Laboratory gravity: the G mystery, Riley Newman. LIGO project update, Stan Whitcomb. Conference Reports PASCOS '94, Peter Saulson. The Vienna Meeting, P. Aichelburg, R. Beig. The Pitt binary black hole grand challenge meeting, Jeff Winicour. International symposium on experimental gravitation at Pakistan,Munawar Karim 10th Pacific coast gravity meeting, Jim Isenberg.
1407.4673
S Habib Mazharimousavi
S. Habib Mazharimousavi and M. Halilsoy
Counterrotational effects on stability of 2+1-dimensional thin-shell wormholes
5 pages, 2 figures, final version published in EPJC
Eur. Phys. J. C (2014) 74:3073
10.1140/epjc/s10052-014-3073-2
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The role of angular momentum in a 2+1-dimensional rotating thin-shell wormhole (TSW) is considered. Particular emphasis is made on stability when the shells (rings) are counterrotating. We find that counter-rotating halves make the TSW supported by the equation of state of a linear gas more stable. Under a small velocity dependent perturbation, however, it becomes unstable.
[ { "created": "Tue, 15 Jul 2014 20:03:32 GMT", "version": "v1" }, { "created": "Mon, 29 Sep 2014 05:54:45 GMT", "version": "v2" } ]
2014-09-30
[ [ "Mazharimousavi", "S. Habib", "" ], [ "Halilsoy", "M.", "" ] ]
The role of angular momentum in a 2+1-dimensional rotating thin-shell wormhole (TSW) is considered. Particular emphasis is made on stability when the shells (rings) are counterrotating. We find that counter-rotating halves make the TSW supported by the equation of state of a linear gas more stable. Under a small velocity dependent perturbation, however, it becomes unstable.
1512.05757
Antonio Enea Romano
Antonio Enea Romano, Sander Mooij, Misao Sasaki
Adiabaticity and gravity theory independent conservation laws for cosmological perturbations
6 pages, accepted in Physics Letters B
null
10.1016/j.physletb.2016.02.054
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We carefully study the implications of adiabaticity for the behavior of cosmological perturbations. There are essentially three similar but different definitions of non-adiabaticity: one is appropriate for a thermodynamic fluid $\delta P_{nad}$, another is for a general matter field $\delta P_{c,nad}$, and the last one is valid only on superhorizon scales. The first two definitions coincide if $c_s^2=c_w^2$ where $c_s$ is the propagation speed of the perturbation, while $c_w^2=\dot P/\dot\rho$. Assuming the adiabaticity in the general sense, $\delta P_{c,nad}=0$, we derive a relation between the lapse function in the comoving sli\-cing $A_c$ and $\delta P_{nad}$ valid for arbitrary matter field in any theory of gravity, by using only momentum conservation. The relation implies that as long as $c_s\neq c_w$, the uniform density, comoving and the proper-time slicings coincide approximately for any gravity theory and for any matter field if $\delta P_{nad}=0$ approximately. In the case of general relativity this gives the equivalence between the comoving curvature perturbation $R_c$ and the uniform density curvature perturbation $\zeta$ on superhorizon scales, and their conservation. We then consider an example in which $c_w=c_s$, where $\delta P_{nad}=\delta P_{c,nad}=0$ exactly, but the equivalence between $R_c$ and $\zeta$ no longer holds. Namely we consider the so-called ultra slow-roll inflation. In this case both $R_c$ and $\zeta$ are not conserved. In particular, as for $\zeta$, we find that it is crucial to take into account the next-to-leading order term in $\zeta$'s spatial gradient expansion to show its non-conservation, even on superhorizon scales. This is an example of the fact that adiabaticity (in the thermodynamic sense) is not always enough to ensure the conservation of $R_c$ or $\zeta$.
[ { "created": "Thu, 17 Dec 2015 20:29:09 GMT", "version": "v1" }, { "created": "Tue, 23 Feb 2016 06:47:09 GMT", "version": "v2" } ]
2016-07-29
[ [ "Romano", "Antonio Enea", "" ], [ "Mooij", "Sander", "" ], [ "Sasaki", "Misao", "" ] ]
We carefully study the implications of adiabaticity for the behavior of cosmological perturbations. There are essentially three similar but different definitions of non-adiabaticity: one is appropriate for a thermodynamic fluid $\delta P_{nad}$, another is for a general matter field $\delta P_{c,nad}$, and the last one is valid only on superhorizon scales. The first two definitions coincide if $c_s^2=c_w^2$ where $c_s$ is the propagation speed of the perturbation, while $c_w^2=\dot P/\dot\rho$. Assuming the adiabaticity in the general sense, $\delta P_{c,nad}=0$, we derive a relation between the lapse function in the comoving sli\-cing $A_c$ and $\delta P_{nad}$ valid for arbitrary matter field in any theory of gravity, by using only momentum conservation. The relation implies that as long as $c_s\neq c_w$, the uniform density, comoving and the proper-time slicings coincide approximately for any gravity theory and for any matter field if $\delta P_{nad}=0$ approximately. In the case of general relativity this gives the equivalence between the comoving curvature perturbation $R_c$ and the uniform density curvature perturbation $\zeta$ on superhorizon scales, and their conservation. We then consider an example in which $c_w=c_s$, where $\delta P_{nad}=\delta P_{c,nad}=0$ exactly, but the equivalence between $R_c$ and $\zeta$ no longer holds. Namely we consider the so-called ultra slow-roll inflation. In this case both $R_c$ and $\zeta$ are not conserved. In particular, as for $\zeta$, we find that it is crucial to take into account the next-to-leading order term in $\zeta$'s spatial gradient expansion to show its non-conservation, even on superhorizon scales. This is an example of the fact that adiabaticity (in the thermodynamic sense) is not always enough to ensure the conservation of $R_c$ or $\zeta$.
2005.03989
Sergio Cacciatori
Sergio L. Cacciatori
Gravitational waves, 100 years later
Extended version of a communication to appear on "Rendiconti dell'Istituto Lombardo dell'Accademia delle Scienze e delle Lettere" in a reduced version (without the appendices)
null
null
null
gr-qc physics.pop-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present a short communication on the recent direct measurements of gravitational waves, made possible by the joint efforts of the LIGO and the Virgo projects. These notes are devoted to a broad audience. In the first part we will present the basic ideas of the theory of relativity, leading to the prediction of the existence of gravitational waves. The second part is devoted to present the main results and consequences of the discovery.
[ { "created": "Fri, 8 May 2020 12:43:34 GMT", "version": "v1" } ]
2020-05-11
[ [ "Cacciatori", "Sergio L.", "" ] ]
We present a short communication on the recent direct measurements of gravitational waves, made possible by the joint efforts of the LIGO and the Virgo projects. These notes are devoted to a broad audience. In the first part we will present the basic ideas of the theory of relativity, leading to the prediction of the existence of gravitational waves. The second part is devoted to present the main results and consequences of the discovery.
gr-qc/9401017
Cenalo Vaz
Cenalo Vaz and Louis Witten
Wilson Loops and Black Holes in 2+1 Dimensions
PHYZZX, 10 pages, UATP-9306
Phys.Lett. B327 (1994) 29-34
10.1016/0370-2693(94)91523-7
null
gr-qc hep-th
null
In 2+1 dimensional Chern-Simons gravity, Wilson loops in the three dimensional Anti de Sitter group, $SO(2,2)$, reproduce the spinning black hole of Ba\~nados, Teitelboim and Zanelli (BTZ) by naturally duplicating the necessary identification of points of a four dimensional globally $SO(2,2)$ invariant space in which the hole appears as an embedding.
[ { "created": "Mon, 17 Jan 1994 22:41:55 GMT", "version": "v1" } ]
2009-10-22
[ [ "Vaz", "Cenalo", "" ], [ "Witten", "Louis", "" ] ]
In 2+1 dimensional Chern-Simons gravity, Wilson loops in the three dimensional Anti de Sitter group, $SO(2,2)$, reproduce the spinning black hole of Ba\~nados, Teitelboim and Zanelli (BTZ) by naturally duplicating the necessary identification of points of a four dimensional globally $SO(2,2)$ invariant space in which the hole appears as an embedding.
2006.11552
Oleg Zaslavskii
O. B. Zaslavskii
Special case of the Ba\~{n}ados-Silk-West effect
12 pages. Matches published version
Phys. Rev. D 102, 044051 (2020)
10.1103/PhysRevD.102.044051
null
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
If two particles collide near the rotating extremal black hole and one of them is fine-tuned, the energy in the center of mass frame $E_{c.m.}$ can grow unbounded. This is the so-called Ba\~{n}ados-Silk-West (BSW) effect. Recently, another type of high energy collisions was considered in which all processes happen in the Schwarzschild background with free falling particles. If the Killing energy $E$ of one of particle is sufficiently small, $E_{c.m.}$ grows unbounded. We show that, however, such a particle cannot be created in any precedent collision with finite energies, angular momenta and masses. Therefore, in contrast to the standard BSW effect, this one cannot be realized if initial particles fall from infinity. If the black hole is electrically charged, such a type of collisions is indeed possible, when a particle with very small $E$ collides with one more particle coming from infinity. Thus the BSW effect is achieved due to collisions of neutral particles in the background of a charged black hole. This requires, however, at least two-step process.
[ { "created": "Sat, 20 Jun 2020 11:31:17 GMT", "version": "v1" }, { "created": "Thu, 6 Aug 2020 14:40:21 GMT", "version": "v2" }, { "created": "Thu, 27 Aug 2020 19:56:29 GMT", "version": "v3" } ]
2020-09-02
[ [ "Zaslavskii", "O. B.", "" ] ]
If two particles collide near the rotating extremal black hole and one of them is fine-tuned, the energy in the center of mass frame $E_{c.m.}$ can grow unbounded. This is the so-called Ba\~{n}ados-Silk-West (BSW) effect. Recently, another type of high energy collisions was considered in which all processes happen in the Schwarzschild background with free falling particles. If the Killing energy $E$ of one of particle is sufficiently small, $E_{c.m.}$ grows unbounded. We show that, however, such a particle cannot be created in any precedent collision with finite energies, angular momenta and masses. Therefore, in contrast to the standard BSW effect, this one cannot be realized if initial particles fall from infinity. If the black hole is electrically charged, such a type of collisions is indeed possible, when a particle with very small $E$ collides with one more particle coming from infinity. Thus the BSW effect is achieved due to collisions of neutral particles in the background of a charged black hole. This requires, however, at least two-step process.
1101.5479
Luisa T. Buchman
James M. Bardeen, Olivier Sarbach, Luisa T. Buchman
Tetrad formalism for numerical relativity on conformally compactified constant mean curvature hypersurfaces
Corrected factor of 2 errors in Eqs. (A8) and (A9) and a few typos; final version
Phys.Rev.D83:104045,2011
10.1103/PhysRevD.83.104045
null
gr-qc math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present a new evolution system for Einstein's field equations which is based on tetrad fields and conformally compactified hyperboloidal spatial hypersurfaces which reach future null infinity. The boost freedom in the choice of the tetrad is fixed by requiring that its timelike leg be orthogonal to the foliation, which consists of constant mean curvature slices. The rotational freedom in the tetrad is fixed by the 3D Nester gauge. With these conditions, the field equations reduce naturally to a first-order constrained symmetric hyperbolic evolution system which is coupled to elliptic equations for the gauge variables. The conformally rescaled equations are given explicitly, and their regularity at future null infinity is discussed. Our formulation is potentially useful for high accuracy numerical modeling of gravitational radiation emitted by inspiraling and merging black hole binaries and other highly relativistic isolated systems.
[ { "created": "Fri, 28 Jan 2011 09:07:39 GMT", "version": "v1" }, { "created": "Wed, 16 Mar 2011 20:52:03 GMT", "version": "v2" }, { "created": "Thu, 5 May 2011 23:37:27 GMT", "version": "v3" } ]
2011-06-07
[ [ "Bardeen", "James M.", "" ], [ "Sarbach", "Olivier", "" ], [ "Buchman", "Luisa T.", "" ] ]
We present a new evolution system for Einstein's field equations which is based on tetrad fields and conformally compactified hyperboloidal spatial hypersurfaces which reach future null infinity. The boost freedom in the choice of the tetrad is fixed by requiring that its timelike leg be orthogonal to the foliation, which consists of constant mean curvature slices. The rotational freedom in the tetrad is fixed by the 3D Nester gauge. With these conditions, the field equations reduce naturally to a first-order constrained symmetric hyperbolic evolution system which is coupled to elliptic equations for the gauge variables. The conformally rescaled equations are given explicitly, and their regularity at future null infinity is discussed. Our formulation is potentially useful for high accuracy numerical modeling of gravitational radiation emitted by inspiraling and merging black hole binaries and other highly relativistic isolated systems.
gr-qc/0503054
Robert Lompay
R.R. Lompay
Deriving Mathisson - Papapetrou equations from relativistic pseudomechanics
5 pages, 0 figures
null
null
null
gr-qc
null
It is shown that the equations of motion of a test point particle with spin in a given gravitational field, so called Mathisson - Papapetrou equations, can be derived from Euler - Lagrange equations of the relativistic pseudomechanics -- relativistic mechanics, which side by side uses the conventional (commuting) and Grassmannian (anticommuting) variables. In this approach the known difficulties of the Mathisson - Papapetrou equations, namely, the problem of the choice of supplementary conditions and the problem of higher derivatives are not appear.
[ { "created": "Sat, 12 Mar 2005 19:15:21 GMT", "version": "v1" } ]
2007-05-23
[ [ "Lompay", "R. R.", "" ] ]
It is shown that the equations of motion of a test point particle with spin in a given gravitational field, so called Mathisson - Papapetrou equations, can be derived from Euler - Lagrange equations of the relativistic pseudomechanics -- relativistic mechanics, which side by side uses the conventional (commuting) and Grassmannian (anticommuting) variables. In this approach the known difficulties of the Mathisson - Papapetrou equations, namely, the problem of the choice of supplementary conditions and the problem of higher derivatives are not appear.
2310.03785
Quentin Henry
Quentin Henry and Fran\c{c}ois Larrouturou and Christophe Le Poncin-Lafitte
Electromagnetic fields in compact binaries: post-Newtonian wave generation and application to double white dwarfs systems
44 pages
Phys. Rev. D 109, 084048 (2024)
10.1103/PhysRevD.109.084048
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
The aim of this work is twofold: (i) to properly define a wave-generation formalism for compact-supported sources embedded in Einstein-Maxwell theory, relying on matched post-Newtonian and multipolar-post-Minkowskian expansions; (ii) to apply this formalism (which is valid for any type of post-Newtonian sources) to the case of two stars with constant and aligned magnetic dipoles, by computing the fluxes of energy and angular momentum to the next-to-leading order, as well as the gravitational amplitude modes. Assuming eccentric orbits, we derive the evolution of orbital parameters, as well as the observables of the system, notably the gravitational phase for quasi-circular orbits. Finally, we give some numerical estimates for the contribution of the magnetic dipoles for some realistic systems.
[ { "created": "Thu, 5 Oct 2023 18:00:00 GMT", "version": "v1" } ]
2024-05-24
[ [ "Henry", "Quentin", "" ], [ "Larrouturou", "François", "" ], [ "Poncin-Lafitte", "Christophe Le", "" ] ]
The aim of this work is twofold: (i) to properly define a wave-generation formalism for compact-supported sources embedded in Einstein-Maxwell theory, relying on matched post-Newtonian and multipolar-post-Minkowskian expansions; (ii) to apply this formalism (which is valid for any type of post-Newtonian sources) to the case of two stars with constant and aligned magnetic dipoles, by computing the fluxes of energy and angular momentum to the next-to-leading order, as well as the gravitational amplitude modes. Assuming eccentric orbits, we derive the evolution of orbital parameters, as well as the observables of the system, notably the gravitational phase for quasi-circular orbits. Finally, we give some numerical estimates for the contribution of the magnetic dipoles for some realistic systems.
1712.09422
David Garfinkle
David Garfinkle
Matters of Gravity, The Newsletter of the Division of Gravitational Physics of the American Physical Society, Volume 50, December 2017
null
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
DGRAV News: We hear that .... APS April Meeting Town Hall Meeting Conference Reports: Hawking Conference Benasque workshop 2017 QIQG 3 Obituary: Remembering Cecile De Witt-Morette
[ { "created": "Tue, 26 Dec 2017 21:27:23 GMT", "version": "v1" } ]
2017-12-29
[ [ "Garfinkle", "David", "" ] ]
DGRAV News: We hear that .... APS April Meeting Town Hall Meeting Conference Reports: Hawking Conference Benasque workshop 2017 QIQG 3 Obituary: Remembering Cecile De Witt-Morette
1208.1357
Valery Kiselev
V. V. Kiselev
Thermodynamical instability of black holes
7 pages
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In contrast to Hawking radiation of black hole with a given spacetime structure, we consider a competitive transition due to a heat transfer from a hotter inner horizon to a colder outer horizon of Kerr black hole, that results in a stable thermodynamical state of extremal black hole. In this process, by supposing an emission of gravitational quanta, we calculate the mass of extremal black hole in the final state of transition.
[ { "created": "Tue, 7 Aug 2012 08:03:20 GMT", "version": "v1" } ]
2012-08-08
[ [ "Kiselev", "V. V.", "" ] ]
In contrast to Hawking radiation of black hole with a given spacetime structure, we consider a competitive transition due to a heat transfer from a hotter inner horizon to a colder outer horizon of Kerr black hole, that results in a stable thermodynamical state of extremal black hole. In this process, by supposing an emission of gravitational quanta, we calculate the mass of extremal black hole in the final state of transition.
gr-qc/0505066
Yavuz Nutku
Y. Nutku
What is the present-day status of The Copernican Principle?
an essay deemed not to be worthy of even an honorable mention
null
null
null
gr-qc
null
I point out that according to the Copernican principle our universe is not unique. The way to make sense out of this statement is for us to construct a gravitational instanton that will tunnel out of our vacuum into another, to form a universe other than our Hubble bubble.
[ { "created": "Fri, 13 May 2005 08:56:47 GMT", "version": "v1" } ]
2007-05-23
[ [ "Nutku", "Y.", "" ] ]
I point out that according to the Copernican principle our universe is not unique. The way to make sense out of this statement is for us to construct a gravitational instanton that will tunnel out of our vacuum into another, to form a universe other than our Hubble bubble.
0803.4482
Pranesh Sundararajan
Pranesh A. Sundararajan
The transition from adiabatic inspiral to geodesic plunge for a compact object around a massive Kerr black hole: Generic orbits
11 pages, 6 figures. Accepted by Phys. Rev. D. New version addresses referee's comments
Phys.Rev.D77:124050,2008
10.1103/PhysRevD.77.124050
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The inspiral of a stellar mass compact object falling into a massive Kerr black hole can be broken into three different regimes: An adiabatic inspiral phase, where the inspiral timescale is much larger than the orbital period; a late-time radial infall, which can be approximated as a plunging geodesic; and a regime where the body transitions from the inspiral to plunge. In earlier work, Ori and Thorne have outlined a method to compute the trajectory during this transition for a compact object in a circular, equatorial orbit. We generalize this technique to include inclination and eccentricity.
[ { "created": "Mon, 31 Mar 2008 15:38:54 GMT", "version": "v1" }, { "created": "Tue, 1 Apr 2008 14:14:32 GMT", "version": "v2" }, { "created": "Thu, 8 May 2008 15:45:12 GMT", "version": "v3" } ]
2008-11-26
[ [ "Sundararajan", "Pranesh A.", "" ] ]
The inspiral of a stellar mass compact object falling into a massive Kerr black hole can be broken into three different regimes: An adiabatic inspiral phase, where the inspiral timescale is much larger than the orbital period; a late-time radial infall, which can be approximated as a plunging geodesic; and a regime where the body transitions from the inspiral to plunge. In earlier work, Ori and Thorne have outlined a method to compute the trajectory during this transition for a compact object in a circular, equatorial orbit. We generalize this technique to include inclination and eccentricity.
1809.01993
Peter K.F. Kuhfittig
Peter K.F. Kuhfittig
Traversable wormholes sustained by an extra spatial dimension
10 pages, no figures
Physical Review D, vol. 98, 064041 (2018)
10.1103/PhysRevD.98.064041
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper explores the effect of an extra spatial dimension on a Morris-Thorne wormhole. After proposing a suitable model, it is shown that under certain conditions, the throat of the wormhole can be threaded with ordinary matter, while the unavoidable violation of the null energy condition can be attributed to the existence of the extra dimension.
[ { "created": "Thu, 6 Sep 2018 13:51:16 GMT", "version": "v1" }, { "created": "Tue, 21 May 2019 14:01:22 GMT", "version": "v2" }, { "created": "Sat, 2 Dec 2023 15:58:02 GMT", "version": "v3" } ]
2023-12-05
[ [ "Kuhfittig", "Peter K. F.", "" ] ]
This paper explores the effect of an extra spatial dimension on a Morris-Thorne wormhole. After proposing a suitable model, it is shown that under certain conditions, the throat of the wormhole can be threaded with ordinary matter, while the unavoidable violation of the null energy condition can be attributed to the existence of the extra dimension.
2403.00882
Rahul Mapari Dr.
R. V. Mapari, D. D. Pawar, V. R. Patil, and J. L. Pawde
Interacting Field Cosmological Model in Lyra Geometry
19 pages
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The paper explores a plane symmetric cosmological model within the framework of the Lyra manifold, incorporating interactions among various fields. These fields include a charged perfect fluid, a mass-less scalar field, and an electromagnetic field. The study focuses on deriving relativistic field equations and exact solutions for this complex system. The relationships between the scalar field (\b{eta}) and the average scale factor (a(t)), as well as between the metric potentials, are assumed to solve the nonlinear field equations. Two specific expansion models are examined: 1) Exponential expansion and 2) Power law expansion. The research delves into the dynamic parameters behavior, observing changes in pressure, density, and cosmological parameters across different models. The findings indicate that while the Universe is expanding, the rate of expansion can vary among the different models. The investigation also involves kinematic parameters, such as jerk and snap parameters derived from the scale factor variation, and compares them to the {\Lambda}CDM model.
[ { "created": "Fri, 1 Mar 2024 09:28:57 GMT", "version": "v1" } ]
2024-03-05
[ [ "Mapari", "R. V.", "" ], [ "Pawar", "D. D.", "" ], [ "Patil", "V. R.", "" ], [ "Pawde", "J. L.", "" ] ]
The paper explores a plane symmetric cosmological model within the framework of the Lyra manifold, incorporating interactions among various fields. These fields include a charged perfect fluid, a mass-less scalar field, and an electromagnetic field. The study focuses on deriving relativistic field equations and exact solutions for this complex system. The relationships between the scalar field (\b{eta}) and the average scale factor (a(t)), as well as between the metric potentials, are assumed to solve the nonlinear field equations. Two specific expansion models are examined: 1) Exponential expansion and 2) Power law expansion. The research delves into the dynamic parameters behavior, observing changes in pressure, density, and cosmological parameters across different models. The findings indicate that while the Universe is expanding, the rate of expansion can vary among the different models. The investigation also involves kinematic parameters, such as jerk and snap parameters derived from the scale factor variation, and compares them to the {\Lambda}CDM model.
1606.07644
Zhi-Chao Zhao
Zhe Chang, Chao-Guang Huang, Zhi-Chao Zhao
Propagation effect of gravitational wave on detector response
null
null
10.1007/s11433-016-0268-1
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The response of a detector to gravitational wave is a function of frequency. When the time a photon moving around in the Fabry-Perot cavities is the same order of the period of a gravitational wave, the phase-difference due to the gravitational wave should be an integral along the path. We present a formula description for detector response to gravitational wave with varied frequencies. The LIGO data for GW150914 and GW 151226 are reexamined in this framework. For GW150924, the traveling time of a photon in the LIGO detector is just a bit larger than a half period of the highest frequency of gravitational wave and the similar result is obtained with LIGO and Virgo collaborations. However, we are not always so luck. In the case of GW151226, the time of a photon traveling in the detector is larger than the period of the highest frequency of gravitational wave and the announced signal cannot match well the template with the initial black hole masses 14.2M$_\odot$ and 7.5M$_\odot$.
[ { "created": "Fri, 24 Jun 2016 11:24:45 GMT", "version": "v1" }, { "created": "Fri, 29 Jul 2016 06:52:56 GMT", "version": "v2" } ]
2016-08-01
[ [ "Chang", "Zhe", "" ], [ "Huang", "Chao-Guang", "" ], [ "Zhao", "Zhi-Chao", "" ] ]
The response of a detector to gravitational wave is a function of frequency. When the time a photon moving around in the Fabry-Perot cavities is the same order of the period of a gravitational wave, the phase-difference due to the gravitational wave should be an integral along the path. We present a formula description for detector response to gravitational wave with varied frequencies. The LIGO data for GW150914 and GW 151226 are reexamined in this framework. For GW150924, the traveling time of a photon in the LIGO detector is just a bit larger than a half period of the highest frequency of gravitational wave and the similar result is obtained with LIGO and Virgo collaborations. However, we are not always so luck. In the case of GW151226, the time of a photon traveling in the detector is larger than the period of the highest frequency of gravitational wave and the announced signal cannot match well the template with the initial black hole masses 14.2M$_\odot$ and 7.5M$_\odot$.
1905.05273
Petya Nedkova
Galin Gyulchev, Petya Nedkova, Tsvetan Vetsov, Stoytcho Yazadjiev
Image of the Janis-Newman-Winicour naked singularity with a thin accretion disk
21 pages; 9 figures
Phys. Rev. D 100, 024055 (2019)
10.1103/PhysRevD.100.024055
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the optical appearance and the apparent radiation flux of a thin accretion disk around the static Janis-Newman-Winicour naked singularity. We confine ourselves to the astrophysically most relevant case, when the solution possesses a photon sphere, assuming that the radiation emitted by the disk is described by the Novikov-Thorne model. The observable images resemble closely the visual appearance of the Schwarzschild black hole, as only quantitative differences are present. For the Janis-Newman-Winicour solution the accretion disk appears smaller, and its emission is characterized by a higher peak of the radiation flux. In addition, the most significant part of the radiation is concentrated in a closer neighbourhood of the flux maximum. The results are obtained independently by two alternative methods, consisting of a semi-analytical scheme using the spherical symmetry of the spacetime, and a fully numerical ray-tracing procedure valid for any stationary and axisymmetric spacetime.
[ { "created": "Mon, 13 May 2019 20:12:41 GMT", "version": "v1" } ]
2019-07-31
[ [ "Gyulchev", "Galin", "" ], [ "Nedkova", "Petya", "" ], [ "Vetsov", "Tsvetan", "" ], [ "Yazadjiev", "Stoytcho", "" ] ]
We study the optical appearance and the apparent radiation flux of a thin accretion disk around the static Janis-Newman-Winicour naked singularity. We confine ourselves to the astrophysically most relevant case, when the solution possesses a photon sphere, assuming that the radiation emitted by the disk is described by the Novikov-Thorne model. The observable images resemble closely the visual appearance of the Schwarzschild black hole, as only quantitative differences are present. For the Janis-Newman-Winicour solution the accretion disk appears smaller, and its emission is characterized by a higher peak of the radiation flux. In addition, the most significant part of the radiation is concentrated in a closer neighbourhood of the flux maximum. The results are obtained independently by two alternative methods, consisting of a semi-analytical scheme using the spherical symmetry of the spacetime, and a fully numerical ray-tracing procedure valid for any stationary and axisymmetric spacetime.
1809.03952
Maur\'icio Richartz
Carolina L. Benone and Lu\'is C. B. Crispino and Carlos A. R. Herdeiro and Maur\'icio Richartz
Synchronized stationary clouds in a static fluid
v2: 7 pages, 4 figures. Accepted for publication in Physics Letters B
Physics Letters B 786 (2018) pp. 442-447
10.1016/j.physletb.2018.10.030
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The existence of stationary bound states for the hydrodynamic velocity field between two concentric cylinders is established. We argue that rotational motion, together with a trapping mechanism for the associated field, is sufficient to mitigate energy dissipation between the cylinders, thus allowing the existence of infinitely long lived modes, which we dub stationary clouds. We demonstrate the existence of such stationary clouds for sound and surface waves when the fluid is static and the internal cylinder rotates with constant angular velocity $\Omega$. These setups provide a unique opportunity for the first experimental observation of synchronized stationary clouds. As in the case of bosonic fields around rotating black holes and black hole analogues, the existence of these clouds relies on a synchronization condition between $\Omega$ and the angular phase velocity of the cloud.
[ { "created": "Tue, 11 Sep 2018 14:59:24 GMT", "version": "v1" }, { "created": "Tue, 16 Oct 2018 23:35:21 GMT", "version": "v2" } ]
2018-11-06
[ [ "Benone", "Carolina L.", "" ], [ "Crispino", "Luís C. B.", "" ], [ "Herdeiro", "Carlos A. R.", "" ], [ "Richartz", "Maurício", "" ] ]
The existence of stationary bound states for the hydrodynamic velocity field between two concentric cylinders is established. We argue that rotational motion, together with a trapping mechanism for the associated field, is sufficient to mitigate energy dissipation between the cylinders, thus allowing the existence of infinitely long lived modes, which we dub stationary clouds. We demonstrate the existence of such stationary clouds for sound and surface waves when the fluid is static and the internal cylinder rotates with constant angular velocity $\Omega$. These setups provide a unique opportunity for the first experimental observation of synchronized stationary clouds. As in the case of bosonic fields around rotating black holes and black hole analogues, the existence of these clouds relies on a synchronization condition between $\Omega$ and the angular phase velocity of the cloud.
0901.2423
Giovanni Arcioni
Giovanni Arcioni, Antoine Suarez
At World's End: Where Complementarity and Irreversibility meet in the Black Hole
5 pages, 4 figures
null
null
null
gr-qc hep-th quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
It is argued that a slight modification of the complementarity principle may help to overcome paradoxes about the observer who falls through the event horizon
[ { "created": "Fri, 16 Jan 2009 16:05:03 GMT", "version": "v1" } ]
2009-01-19
[ [ "Arcioni", "Giovanni", "" ], [ "Suarez", "Antoine", "" ] ]
It is argued that a slight modification of the complementarity principle may help to overcome paradoxes about the observer who falls through the event horizon
1003.3120
George Lukes Gerakopoulos
Georgios Lukes-Gerakopoulos, Theocharis A. Apostolatos, George Contopoulos
An observable signature of a background deviating from Kerr
25 pages, 15 figures
Phys.Rev.D81:124005,2010
10.1103/PhysRevD.81.124005
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
By detecting gravitational wave signals from extreme mass ratio inspiraling sources (EMRIs) we will be given the opportunity to check our theoretical expectations regarding the nature of supermassive bodies that inhabit the central regions of galaxies. We have explored some qualitatively new features that a perturbed Kerr metric induces in its geodesic orbits. Since a generic perturbed Kerr metric does not possess all the special symmetries of a Kerr metric, the geodesic equations in the former case are described by a slightly nonintegrable Hamiltonian system. According to the Poincar\'{e}-Birkhoff theorem this causes the appearance of the so-called Birkhoff chains of islands on the corresponding surfaces of section in between the anticipated KAM curves of the integrable Kerr case, whenever the intrinsic frequencies of the system are at resonance. The chains of islands are characterized by finite width, i.e. there is a finite range of initial conditions that correspond to a particular resonance and consequently to a constant rational ratio of intrinsic frequencies. Thus while the EMRI changes adiabatically by radiating energy and angular momentum, by monitoring the frequencies of a signal we can look for a transient pattern, in the form of a plateau, in the evolution of their ratio. We have shown that such a plateau is anticipated to be apparent in a quite large fraction of possible orbital characteristics if the central gravitating source is not a Kerr black hole. Moreover the plateau in the ratio of frequencies is expected to be more prominent at specific rational values that correspond to the strongest resonances. This gives a possible observational detection of such non-Kerr exotic objects.
[ { "created": "Tue, 16 Mar 2010 10:32:35 GMT", "version": "v1" } ]
2014-11-20
[ [ "Lukes-Gerakopoulos", "Georgios", "" ], [ "Apostolatos", "Theocharis A.", "" ], [ "Contopoulos", "George", "" ] ]
By detecting gravitational wave signals from extreme mass ratio inspiraling sources (EMRIs) we will be given the opportunity to check our theoretical expectations regarding the nature of supermassive bodies that inhabit the central regions of galaxies. We have explored some qualitatively new features that a perturbed Kerr metric induces in its geodesic orbits. Since a generic perturbed Kerr metric does not possess all the special symmetries of a Kerr metric, the geodesic equations in the former case are described by a slightly nonintegrable Hamiltonian system. According to the Poincar\'{e}-Birkhoff theorem this causes the appearance of the so-called Birkhoff chains of islands on the corresponding surfaces of section in between the anticipated KAM curves of the integrable Kerr case, whenever the intrinsic frequencies of the system are at resonance. The chains of islands are characterized by finite width, i.e. there is a finite range of initial conditions that correspond to a particular resonance and consequently to a constant rational ratio of intrinsic frequencies. Thus while the EMRI changes adiabatically by radiating energy and angular momentum, by monitoring the frequencies of a signal we can look for a transient pattern, in the form of a plateau, in the evolution of their ratio. We have shown that such a plateau is anticipated to be apparent in a quite large fraction of possible orbital characteristics if the central gravitating source is not a Kerr black hole. Moreover the plateau in the ratio of frequencies is expected to be more prominent at specific rational values that correspond to the strongest resonances. This gives a possible observational detection of such non-Kerr exotic objects.
1712.04342
Kirill Bronnikov
K.A. Bronnikov
Comment on "Construction of regular black holes in general relativity"
3 pages, no figures. arXiv admin note: text overlap with arXiv:1708.08125
Phys. Rev. D 96 (12), 128501 (2017)
10.1103/PhysRevD.96.128501
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
It is claimed that the paper by Zhong-Ying Fan and Xiaobao Wang [Phys. Rev. D 94, 124027 (2016), arXiv: 1610.02636] on nonlinear electrodynamics coupled to general relativity, being correct in general, in some respects repeats previously obtained results without giving proper references. There is also an important point missing in this paper, but necessary for understanding the physics of the system: in solutions with an electric charge, a regular center requires a non-Maxwell behavior of the Lagrangian function $L(f),\ (f= F_{\mu\nu} F^{\mu\nu})$ at small $f$. Therefore, in all electric regular black hole solutions with a Reissner-Nordstr\"om asymptotic, the Lagrangian $L(f)$ is different in different parts of space, and the electromagnetic field behaves in a singular way at surfaces where $L(f)$ suffers branching.
[ { "created": "Sun, 10 Dec 2017 19:46:45 GMT", "version": "v1" } ]
2017-12-13
[ [ "Bronnikov", "K. A.", "" ] ]
It is claimed that the paper by Zhong-Ying Fan and Xiaobao Wang [Phys. Rev. D 94, 124027 (2016), arXiv: 1610.02636] on nonlinear electrodynamics coupled to general relativity, being correct in general, in some respects repeats previously obtained results without giving proper references. There is also an important point missing in this paper, but necessary for understanding the physics of the system: in solutions with an electric charge, a regular center requires a non-Maxwell behavior of the Lagrangian function $L(f),\ (f= F_{\mu\nu} F^{\mu\nu})$ at small $f$. Therefore, in all electric regular black hole solutions with a Reissner-Nordstr\"om asymptotic, the Lagrangian $L(f)$ is different in different parts of space, and the electromagnetic field behaves in a singular way at surfaces where $L(f)$ suffers branching.
0906.1570
Claudio Simeone
Martin G. Richarte and Claudio Simeone
More about thin-shell wormholes associated to cosmic strings
8 pages; accepted for publication in Physical Review D
Phys.Rev.D79:127502,2009
10.1103/PhysRevD.79.127502
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Previous analysis about thin-shell wormholes associated to cosmic strings are extended. More evidence is found supporting the conjecture that, under reasonable assumptions about the equations of state of matter on the shell, the configurations are not stable under radial velocity perturbations.
[ { "created": "Mon, 8 Jun 2009 19:35:09 GMT", "version": "v1" } ]
2009-07-09
[ [ "Richarte", "Martin G.", "" ], [ "Simeone", "Claudio", "" ] ]
Previous analysis about thin-shell wormholes associated to cosmic strings are extended. More evidence is found supporting the conjecture that, under reasonable assumptions about the equations of state of matter on the shell, the configurations are not stable under radial velocity perturbations.
2007.04354
Abdulrahim Al Balushi
Michael T.N. Imseis, Abdulrahim Al Balushi, Robert B. Mann
Null Hypersurfaces in Kerr-Newman-AdS Black Hole and Super-Entropic Black Hole Spacetimes
some figures updated
null
10.1088/1361-6382/abd3e0
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A three-dimensional light-like foliation of a spacetime geometry is one particular way of studying its light cone structure and has important applications in numerical relativity. In this paper, we execute such a foliation for the Kerr-Newman-AdS black hole geometry and compare it with the lightlike foliations of the Kerr-AdS and Kerr-Newman black holes. We derive the equations that govern this slicing and study their properties. In particular, we find that these null hypersurfaces develop caustics inside the inner horizon of the Kerr-Newman-AdS black hole, in strong contrast to the Kerr-AdS case. We then take the ultra-spinning limit of the Kerr-Newman-AdS spacetime, leading to what is known as a Super-Entropic black hole, and show that the null hypersurfaces develop caustics at a finite distance outside the event horizon of this black hole. As an application, we construct Kruskal coordinates for both the Kerr-Newman-AdS black hole and its ultra-spinning counterpart.
[ { "created": "Wed, 8 Jul 2020 18:17:49 GMT", "version": "v1" }, { "created": "Tue, 4 Aug 2020 15:06:47 GMT", "version": "v2" } ]
2021-02-03
[ [ "Imseis", "Michael T. N.", "" ], [ "Balushi", "Abdulrahim Al", "" ], [ "Mann", "Robert B.", "" ] ]
A three-dimensional light-like foliation of a spacetime geometry is one particular way of studying its light cone structure and has important applications in numerical relativity. In this paper, we execute such a foliation for the Kerr-Newman-AdS black hole geometry and compare it with the lightlike foliations of the Kerr-AdS and Kerr-Newman black holes. We derive the equations that govern this slicing and study their properties. In particular, we find that these null hypersurfaces develop caustics inside the inner horizon of the Kerr-Newman-AdS black hole, in strong contrast to the Kerr-AdS case. We then take the ultra-spinning limit of the Kerr-Newman-AdS spacetime, leading to what is known as a Super-Entropic black hole, and show that the null hypersurfaces develop caustics at a finite distance outside the event horizon of this black hole. As an application, we construct Kruskal coordinates for both the Kerr-Newman-AdS black hole and its ultra-spinning counterpart.
2309.05696
Ashish Kumar Meena
Ashish Kumar Meena and Prasenjit Saha
What are the parities of photon-ring images near a black hole?
11 pages. 7 figures. 3 appendix. Accepted in OJA
null
10.21105/astro.2309.05696
null
gr-qc astro-ph.CO
http://creativecommons.org/licenses/by/4.0/
Light that grazes a black-hole event horizon can loop around one or more times before escaping again, resulting for distance observers in an infinite sequence of ever fainter and more delayed images near the black hole shadow. In the case of the M87 and Sgr A$^*$ back holes, the first of these so-called photon-ring images have now been observed. A question then arises: are such images minima, maxima, or saddle-points in the sense of Fermat's principle in gravitational lensing? or more briefly, the title question above. In the theory of lensing by weak gravitational fields, image parities are readily found by considering the time-delay surface (also called the Fermat potential or the arrival-time surface). In this work, we extend the notion of the time delay surface to strong gravitational fields and compute the surface for a Schwarzschild black hole. The time-delay surface is the difference of two wavefronts, one travelling forward from the source and one travelling backwards from the observer. Image parities are read off from the topography of the surface, exactly as in the weak-field regime, but the surface itself is more complicated. Of the images, furthest from the black hole and similar to the weak-field limit, are a minimum and a saddle point. The strong field repeats the pattern, corresponding to light taking one or more loops around the back hole. In between, there are steeply-rising walls in the time-delay surface, which can be interpreted as maxima and saddle points that are infinitely delayed and not observable -- these correspond to light rays taking a U-turn around the black hole.
[ { "created": "Mon, 11 Sep 2023 18:00:00 GMT", "version": "v1" }, { "created": "Thu, 21 Dec 2023 09:22:30 GMT", "version": "v2" } ]
2024-01-02
[ [ "Meena", "Ashish Kumar", "" ], [ "Saha", "Prasenjit", "" ] ]
Light that grazes a black-hole event horizon can loop around one or more times before escaping again, resulting for distance observers in an infinite sequence of ever fainter and more delayed images near the black hole shadow. In the case of the M87 and Sgr A$^*$ back holes, the first of these so-called photon-ring images have now been observed. A question then arises: are such images minima, maxima, or saddle-points in the sense of Fermat's principle in gravitational lensing? or more briefly, the title question above. In the theory of lensing by weak gravitational fields, image parities are readily found by considering the time-delay surface (also called the Fermat potential or the arrival-time surface). In this work, we extend the notion of the time delay surface to strong gravitational fields and compute the surface for a Schwarzschild black hole. The time-delay surface is the difference of two wavefronts, one travelling forward from the source and one travelling backwards from the observer. Image parities are read off from the topography of the surface, exactly as in the weak-field regime, but the surface itself is more complicated. Of the images, furthest from the black hole and similar to the weak-field limit, are a minimum and a saddle point. The strong field repeats the pattern, corresponding to light taking one or more loops around the back hole. In between, there are steeply-rising walls in the time-delay surface, which can be interpreted as maxima and saddle points that are infinitely delayed and not observable -- these correspond to light rays taking a U-turn around the black hole.
gr-qc/9904067
Friedrich W. Hehl
Yuri N. Obukhov (Moscow/Cologne) and Friedrich W. Hehl (Cologne)
Spacetime metric from linear electrodynamics
4 pages' latex-script
Phys.Lett. B458 (1999) 466-470
10.1016/S0370-2693(99)00643-7
Cologne-THP-H-99/03
gr-qc hep-th
null
The Maxwell equations are formulated on an arbitrary (1+3)-dimensional manifold. Then, imposing a (constrained) linear constitutive relation between electromagnetic field $(E,B)$ and excitation $({\cal D},{\cal H})$, we derive the metric of spacetime therefrom.
[ { "created": "Mon, 26 Apr 1999 21:52:21 GMT", "version": "v1" }, { "created": "Mon, 14 Jun 1999 14:04:37 GMT", "version": "v2" } ]
2009-10-31
[ [ "Obukhov", "Yuri N.", "", "Moscow/Cologne" ], [ "Hehl", "Friedrich W.", "", "Cologne" ] ]
The Maxwell equations are formulated on an arbitrary (1+3)-dimensional manifold. Then, imposing a (constrained) linear constitutive relation between electromagnetic field $(E,B)$ and excitation $({\cal D},{\cal H})$, we derive the metric of spacetime therefrom.
2403.14164
Shao-Wen Wei
Ke Chen, Shao-Wen Wei
Motion of spinning particles around a polymer black hole in loop quantum gravity
11 pages, 12 figures
null
null
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
In the curved spacetime background, the trajectory of a spinning test particle will deviate from the geodesic. Using the effective potential method, we study the motion of a spinning test particle on the equatorial plane of a polymer black hole in loop quantum gravity described by the Mathisson-Papapetrou-Dixon equations with minimal spin-gravity interaction. We find that for the bounded orbits in the radial direction, the particle's motion is timelike when its spin is small. The radial range of the orbit and its eccentricity decrease with the loop quantum gravity parameter. However, when the particle takes a large enough spin, we observe an interesting phenomenon that the timelike and spacelike motions alternately appear while are separated by a critical radius. Outside the critical radius, the motion is timelike, however inside it is spacelike, and on the radius $r_c$ it is null. To explore more observable effects of the loop quantum gravity parameter on the motion of the spinning particle, we focus our attention on the circular orbits, particularly the innermost stable circular orbits, near the black hole. The result shows that for the same spin, there are two different innermost stable circular orbits, one with a larger radius and the other with a smaller radius. Both the radii decrease as the loop quantum gravity parameter increases. More significantly, with the increase of the spin of the particle, the small innermost stable circular orbit transition from timelike to spacelike, while the one with large radius does not. Instead, it terminates at a certain value of spin. All the results present the significant influences of the loop quantum gravity parameter on the motion of the spinning particles.
[ { "created": "Thu, 21 Mar 2024 06:33:10 GMT", "version": "v1" } ]
2024-03-22
[ [ "Chen", "Ke", "" ], [ "Wei", "Shao-Wen", "" ] ]
In the curved spacetime background, the trajectory of a spinning test particle will deviate from the geodesic. Using the effective potential method, we study the motion of a spinning test particle on the equatorial plane of a polymer black hole in loop quantum gravity described by the Mathisson-Papapetrou-Dixon equations with minimal spin-gravity interaction. We find that for the bounded orbits in the radial direction, the particle's motion is timelike when its spin is small. The radial range of the orbit and its eccentricity decrease with the loop quantum gravity parameter. However, when the particle takes a large enough spin, we observe an interesting phenomenon that the timelike and spacelike motions alternately appear while are separated by a critical radius. Outside the critical radius, the motion is timelike, however inside it is spacelike, and on the radius $r_c$ it is null. To explore more observable effects of the loop quantum gravity parameter on the motion of the spinning particle, we focus our attention on the circular orbits, particularly the innermost stable circular orbits, near the black hole. The result shows that for the same spin, there are two different innermost stable circular orbits, one with a larger radius and the other with a smaller radius. Both the radii decrease as the loop quantum gravity parameter increases. More significantly, with the increase of the spin of the particle, the small innermost stable circular orbit transition from timelike to spacelike, while the one with large radius does not. Instead, it terminates at a certain value of spin. All the results present the significant influences of the loop quantum gravity parameter on the motion of the spinning particles.
gr-qc/9907095
Sawa Manoff
Sawa Manoff
Conformal derivative and conformal transports over spaces with an affine connection and metrics
17 pages, LaTeX, submitted for publication in Intern. J. of Math. Phys., Nonlinear Phenomena and Group Theory
Int.J.Mod.Phys. A15 (2000) 679-696
10.1142/S0217751X00000343
null
gr-qc
null
Transports preserving the angle between two contravariant vector fields but changing their lengths proportional to their own lengths are introduced as `conformal' transports and investigated over spaces with one affine connection and metric. They are more general than the Fermi-Walker transports. In an analogous way as in the case of Fermi-Walker transports a conformal covariant differential operator and its conformal derivative are defined and considered over spaces with one affine connection and metric. Different special types of conformal transports are determined inducing also Fermi-Walker transports for orthogonal vector fields as special cases. Conditions under which the length of a non-null contravariant vector field could swing as a homogeneous harmonic oscillator are established. The results obtained regardless of any concrete field (gravitational) theory could have direct applications in such types of theories. PACS numbers: 04.90.+e; 04.50.+h; 12.10.Gq; 02.40.Vh
[ { "created": "Wed, 28 Jul 1999 08:49:55 GMT", "version": "v1" }, { "created": "Thu, 12 Oct 2000 07:43:00 GMT", "version": "v2" } ]
2009-10-31
[ [ "Manoff", "Sawa", "" ] ]
Transports preserving the angle between two contravariant vector fields but changing their lengths proportional to their own lengths are introduced as `conformal' transports and investigated over spaces with one affine connection and metric. They are more general than the Fermi-Walker transports. In an analogous way as in the case of Fermi-Walker transports a conformal covariant differential operator and its conformal derivative are defined and considered over spaces with one affine connection and metric. Different special types of conformal transports are determined inducing also Fermi-Walker transports for orthogonal vector fields as special cases. Conditions under which the length of a non-null contravariant vector field could swing as a homogeneous harmonic oscillator are established. The results obtained regardless of any concrete field (gravitational) theory could have direct applications in such types of theories. PACS numbers: 04.90.+e; 04.50.+h; 12.10.Gq; 02.40.Vh
1512.03137
Eric Thrane
Eric Thrane, Russell P Anderson, Yuri Levin and Lincoln D Turner
Suspending test masses in terrestrial millihertz gravitational-wave detectors: a case study with a magnetic assisted torsion pendulum
6 pages, 4 figures
null
null
null
gr-qc astro-ph.IM physics.ins-det
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Current terrestrial gravitational-wave detectors operate at frequencies above 10 Hz. There is strong astrophysical motivation to construct low-frequency gravitational-wave detectors capable of observing 10 mHz - 10Hz signals. While space-based detectors provide one means of achieving this end, one may also consider terretrial detectors. However, there are numerous technological challenges. In particular, it is difficult to isolate test masses so that they are both seismically isolated and freely falling under the influence of gravity at millihertz frequencies. We investigate the challenges of low-frequency suspension in a hypothetical terrestrial detector. As a case study, we consider a Magnetically Assisted Gravitational-wave Pendulum Intorsion (MAGPI) suspension design. We construct a noise budget to estimate some of the required specifications. In doing so, we identify what are likely to be a number of generic limiting noise sources for terrestrial millihertz gravitational-wave suspension systems (as well as some peculiar to the MAGPI design). We highlight significant experimental challenges in order to argue that the development of millihertz suspensions will be a daunting task. Any system that relies on magnets faces even greater challenges. Entirely mechanical designs such as Zollner pendulums may provide the best path forward.
[ { "created": "Thu, 10 Dec 2015 04:38:32 GMT", "version": "v1" }, { "created": "Thu, 15 Dec 2016 11:53:13 GMT", "version": "v2" }, { "created": "Fri, 24 Mar 2017 00:49:46 GMT", "version": "v3" } ]
2017-03-27
[ [ "Thrane", "Eric", "" ], [ "Anderson", "Russell P", "" ], [ "Levin", "Yuri", "" ], [ "Turner", "Lincoln D", "" ] ]
Current terrestrial gravitational-wave detectors operate at frequencies above 10 Hz. There is strong astrophysical motivation to construct low-frequency gravitational-wave detectors capable of observing 10 mHz - 10Hz signals. While space-based detectors provide one means of achieving this end, one may also consider terretrial detectors. However, there are numerous technological challenges. In particular, it is difficult to isolate test masses so that they are both seismically isolated and freely falling under the influence of gravity at millihertz frequencies. We investigate the challenges of low-frequency suspension in a hypothetical terrestrial detector. As a case study, we consider a Magnetically Assisted Gravitational-wave Pendulum Intorsion (MAGPI) suspension design. We construct a noise budget to estimate some of the required specifications. In doing so, we identify what are likely to be a number of generic limiting noise sources for terrestrial millihertz gravitational-wave suspension systems (as well as some peculiar to the MAGPI design). We highlight significant experimental challenges in order to argue that the development of millihertz suspensions will be a daunting task. Any system that relies on magnets faces even greater challenges. Entirely mechanical designs such as Zollner pendulums may provide the best path forward.
gr-qc/0512064
Nadja Magalh\~aes Sim\~ao
Nadja S. Magalhaes, Rubem M. Marinho Jr., Odylio D. Aguiar, C. Frajuca
Can lightning be a noise source for a spherical gravitational wave antenna?
5 pages, 6 figures
Phys.Rev. D72 (2005) 102003
10.1103/PhysRevD.72.102003
null
gr-qc
null
The detection of gravitational waves is a very active research field at the moment. In Brazil the gravitational wave detector is called Mario SCHENBERG. Due to its high sensitivity it is necessary to model mathematically all known noise sources so that digital filters can be developed that maximize the signal-to-noise ratio. One of the noise sources that must be considered are the disturbances caused by electromagnetic pulses due to lightning close to the experiment. Such disturbances may influence the vibrations of the antenna's normal modes and mask possible gravitational wave signals. In this work we model the interaction between lightning and SCHENBERG antenna and calculate the intensity of the noise due to a close lightning stroke in the detected signal. We find that the noise generated does not disturb the experiment significantly.
[ { "created": "Sun, 11 Dec 2005 16:15:29 GMT", "version": "v1" } ]
2009-11-11
[ [ "Magalhaes", "Nadja S.", "" ], [ "Marinho", "Rubem M.", "Jr." ], [ "Aguiar", "Odylio D.", "" ], [ "Frajuca", "C.", "" ] ]
The detection of gravitational waves is a very active research field at the moment. In Brazil the gravitational wave detector is called Mario SCHENBERG. Due to its high sensitivity it is necessary to model mathematically all known noise sources so that digital filters can be developed that maximize the signal-to-noise ratio. One of the noise sources that must be considered are the disturbances caused by electromagnetic pulses due to lightning close to the experiment. Such disturbances may influence the vibrations of the antenna's normal modes and mask possible gravitational wave signals. In this work we model the interaction between lightning and SCHENBERG antenna and calculate the intensity of the noise due to a close lightning stroke in the detected signal. We find that the noise generated does not disturb the experiment significantly.
gr-qc/0103090
Evgeny Sorkin
Evgeny Sorkin and Tsvi Piran
Formation and Evaporation of Charged Black Holes
23 pages, 7 eps figures, RevTex, accepted for publication in Phys. Rev. D
Phys.Rev.D63:124024,2001
10.1103/PhysRevD.63.124024
null
gr-qc
null
We investigate the dynamical formation and evaporation of a spherically symmetric charged black hole. We study the self-consistent one loop order semiclassical back-reaction problem. To this end the mass-evaporation is modeled by an expectation value of the stress-energy tensor of a neutral massless scalar field, while the charge is not radiated away. We observe the formation of an initially non extremal black hole which tends toward the extremal black hole $M=Q$, emitting Hawking radiation. If also the discharge due to the instability of vacuum to pair creation in strong electric fields occurs, then the black hole discharges and evaporates simultaneously and decays regularly until the scale where the semiclassical approximation breaks down. We calculate the rates of the mass and the charge loss and estimate the life-time of the decaying black holes.
[ { "created": "Sun, 25 Mar 2001 08:02:15 GMT", "version": "v1" } ]
2014-11-17
[ [ "Sorkin", "Evgeny", "" ], [ "Piran", "Tsvi", "" ] ]
We investigate the dynamical formation and evaporation of a spherically symmetric charged black hole. We study the self-consistent one loop order semiclassical back-reaction problem. To this end the mass-evaporation is modeled by an expectation value of the stress-energy tensor of a neutral massless scalar field, while the charge is not radiated away. We observe the formation of an initially non extremal black hole which tends toward the extremal black hole $M=Q$, emitting Hawking radiation. If also the discharge due to the instability of vacuum to pair creation in strong electric fields occurs, then the black hole discharges and evaporates simultaneously and decays regularly until the scale where the semiclassical approximation breaks down. We calculate the rates of the mass and the charge loss and estimate the life-time of the decaying black holes.
2107.00917
Alexander Kamenshchik
Alexander Yu. Kamenshchik, Jeinny Nallely Perez Rodriguez and Tereza Vardanyan
Time and Evolution in Quantum and Classical Cosmology
30 pages, published in Universe 7, 219 (2021) in the Special Issue on "Quantum Cosmology", Ed. Paulo Vargas Moniz
Universe 7, 219 (2021)
10.3390/universe7070219
null
gr-qc quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We analyze the issue of dynamical evolution and time in quantum cosmology. We emphasize the problem of choice of phase space variables that can play the role of a time parameter in such a way that for expectation values of quantum operators the classical evolution is reproduced. We show that it is neither necessary nor sufficient for the Poisson bracket between the time variable and the super-Hamiltonian to be equal to unity in all of the phase space. We also discuss the question of switching between different internal times as well as the Montevideo interpretation of quantum theory.
[ { "created": "Fri, 2 Jul 2021 09:17:55 GMT", "version": "v1" } ]
2021-07-05
[ [ "Kamenshchik", "Alexander Yu.", "" ], [ "Rodriguez", "Jeinny Nallely Perez", "" ], [ "Vardanyan", "Tereza", "" ] ]
We analyze the issue of dynamical evolution and time in quantum cosmology. We emphasize the problem of choice of phase space variables that can play the role of a time parameter in such a way that for expectation values of quantum operators the classical evolution is reproduced. We show that it is neither necessary nor sufficient for the Poisson bracket between the time variable and the super-Hamiltonian to be equal to unity in all of the phase space. We also discuss the question of switching between different internal times as well as the Montevideo interpretation of quantum theory.
gr-qc/0210035
Thomas Waters
Brien C Nolan and Thomas J Waters
Cauchy horizon stability in self-similar collapse: scalar radiation
10 pages. To appear in Phys Rev D
Phys.Rev.D66:104012,2002
10.1103/PhysRevD.66.104012
null
gr-qc
null
The stability of the Cauchy horizon in spherically symmetric self-similar collapse is studied by determining the flux of scalar radiation impinging on the horizon. This flux is found to be finite.
[ { "created": "Fri, 11 Oct 2002 16:09:20 GMT", "version": "v1" } ]
2010-11-19
[ [ "Nolan", "Brien C", "" ], [ "Waters", "Thomas J", "" ] ]
The stability of the Cauchy horizon in spherically symmetric self-similar collapse is studied by determining the flux of scalar radiation impinging on the horizon. This flux is found to be finite.
2404.01262
Artem Talanov
Yoong S. Phang and Artem V. Talanov
Engineered Graviton Condensates in a Room-Temperature Superconductor for a Unified Quantum Fibonacci Field Theory
21 pages, 19 figures. This an April Fools submission following the tradition of joke papers on arXiv for April Fools
null
null
null
gr-qc cond-mat.supr-con quant-ph
http://creativecommons.org/licenses/by/4.0/
In the quest to unify quantum mechanics with general relativity, the concept of gravitons as quantum carriers of gravitational force stands as a pivotal yet unproven hypothesis. This work pioneers a bold approach to graviton condensation via an innovative ambient superconductor, synthesized through a groundbreaking yet theoretically plausible physics process. Building on recent superconductivity breakthroughs, we introduce a novel ambient superconductor fabricated through the bombardment of a dilute Bose-Einstein condensate with high-energy gamma photons, under precisely controlled magnetic fields oscillating in Fibonacci sequence patterns. This process, designed to exploit quantum coherence at macroscopic scales, fosters conditions ripe for graviton condensation. Here we demonstrate the successful induction of a graviton condensate within our engineered superconductor, marking a significant stride towards integrating gravitational and electromagnetic forces at a quantum level. This discovery not only defies traditional views separating the four fundamental interactions but also lays down a tangible groundwork for quantum gravity. Our results challenge existing paradigms by indicating that graviton condensation, mediated through tailored superconducting states, can unlock new aspects of fundamental physics. This graviton condensate represents a critical step towards a unified field theory, bridging the gap between quantum mechanics and general relativity. This investigation not only extends the boundaries of theoretical physics but also hints at potential future technologies harnessing the quantum interplay of gravitational and electromagnetic forces. Through imaginative yet rigorous scientific inquiry, this study underscores the limitless potential of physics to explore and unify the natural world's most fundamental forces.
[ { "created": "Mon, 1 Apr 2024 17:34:22 GMT", "version": "v1" } ]
2024-04-02
[ [ "Phang", "Yoong S.", "" ], [ "Talanov", "Artem V.", "" ] ]
In the quest to unify quantum mechanics with general relativity, the concept of gravitons as quantum carriers of gravitational force stands as a pivotal yet unproven hypothesis. This work pioneers a bold approach to graviton condensation via an innovative ambient superconductor, synthesized through a groundbreaking yet theoretically plausible physics process. Building on recent superconductivity breakthroughs, we introduce a novel ambient superconductor fabricated through the bombardment of a dilute Bose-Einstein condensate with high-energy gamma photons, under precisely controlled magnetic fields oscillating in Fibonacci sequence patterns. This process, designed to exploit quantum coherence at macroscopic scales, fosters conditions ripe for graviton condensation. Here we demonstrate the successful induction of a graviton condensate within our engineered superconductor, marking a significant stride towards integrating gravitational and electromagnetic forces at a quantum level. This discovery not only defies traditional views separating the four fundamental interactions but also lays down a tangible groundwork for quantum gravity. Our results challenge existing paradigms by indicating that graviton condensation, mediated through tailored superconducting states, can unlock new aspects of fundamental physics. This graviton condensate represents a critical step towards a unified field theory, bridging the gap between quantum mechanics and general relativity. This investigation not only extends the boundaries of theoretical physics but also hints at potential future technologies harnessing the quantum interplay of gravitational and electromagnetic forces. Through imaginative yet rigorous scientific inquiry, this study underscores the limitless potential of physics to explore and unify the natural world's most fundamental forces.
gr-qc/0312029
Hongbao Zhang
Hongbao Zhang, Zhoujian Cao, Xuefei Gong and Wei Zhou
Quasinormal modes for Weyl neutrino field in R-N black holes
13 pages, 4 figures, and 2 tables, references added, typos corrected, accepted for publication in Classical and Quantum Gravity
Class.Quant.Grav. 21 (2004) 917-926
10.1088/0264-9381/21/4/011
null
gr-qc
null
We employ WKB approximation up to the third order to determine the low-lying quasinormal modes for Weyl neutrino field in R-N black holes, which are the most relevant to the evolution of the field around a black hole in the intermediate stage. It is showed that the quasinormal mode frequencies for Weyl neutrino field in R-N black holes are different from those in Schwartzchild black holes owning to the charge-induced additional gravitation, and the variations of the quasinormal mode frequencies for Weyl neutrino field are similar to those for integral spin fields in R-N black holes.
[ { "created": "Thu, 4 Dec 2003 14:47:48 GMT", "version": "v1" }, { "created": "Mon, 15 Dec 2003 04:12:46 GMT", "version": "v2" } ]
2009-11-10
[ [ "Zhang", "Hongbao", "" ], [ "Cao", "Zhoujian", "" ], [ "Gong", "Xuefei", "" ], [ "Zhou", "Wei", "" ] ]
We employ WKB approximation up to the third order to determine the low-lying quasinormal modes for Weyl neutrino field in R-N black holes, which are the most relevant to the evolution of the field around a black hole in the intermediate stage. It is showed that the quasinormal mode frequencies for Weyl neutrino field in R-N black holes are different from those in Schwartzchild black holes owning to the charge-induced additional gravitation, and the variations of the quasinormal mode frequencies for Weyl neutrino field are similar to those for integral spin fields in R-N black holes.
2104.00555
Jens Boos
Jens Boos
Non-singular "Gauss" black hole from non-locality: a simple model with a de Sitter core, mass gap, and no inner horizon
11 pages, 2 figures; fixed a typo in Eq.(4), added references and additional discussion. Extended version of an Essay written for the Gravity Research Foundation 2021 Awards for Essays on Gravitation
null
null
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Cutting out an infinite tube around $r=0$ formally removes the Schwarzschild singularity, but without a physical mechanism this procedure seems ad hoc and artificial. In this Essay we provide such a mechanism by means of non-locality. Motivated by the Gauss law we define a suitable radius variable as the inverse of a regular non-local potential, and use this variable to model a non-singular black hole. The resulting geometry has a de Sitter core, but for generic values of the regulator there is no inner horizon, saving this model from potential issues via mass inflation. An outer horizon only exists for masses above a critical threshold, thereby reproducing the conjectured "mass gap" for black holes in non-local theories. The geometry's density and pressure terms decrease exponentially, thereby rendering it an almost-exact vacuum solution of the Einstein equations outside of astrophysical black holes.
[ { "created": "Thu, 1 Apr 2021 15:30:02 GMT", "version": "v1" }, { "created": "Mon, 5 Apr 2021 19:24:06 GMT", "version": "v2" } ]
2021-04-07
[ [ "Boos", "Jens", "" ] ]
Cutting out an infinite tube around $r=0$ formally removes the Schwarzschild singularity, but without a physical mechanism this procedure seems ad hoc and artificial. In this Essay we provide such a mechanism by means of non-locality. Motivated by the Gauss law we define a suitable radius variable as the inverse of a regular non-local potential, and use this variable to model a non-singular black hole. The resulting geometry has a de Sitter core, but for generic values of the regulator there is no inner horizon, saving this model from potential issues via mass inflation. An outer horizon only exists for masses above a critical threshold, thereby reproducing the conjectured "mass gap" for black holes in non-local theories. The geometry's density and pressure terms decrease exponentially, thereby rendering it an almost-exact vacuum solution of the Einstein equations outside of astrophysical black holes.
1112.5308
Laur J\"arv
Laur J\"arv, Piret Kuusk, Margus Saal
Scalar-tensor cosmologies with dust matter in the general relativity limit
15 pages
null
10.1103/PhysRevD.85.064013
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider flat Friedmann-Lema\^{\i}tre-Robertson-Walker cosmological models in the framework of general scalar-tensor theories of gravity with arbitrary coupling functions, set in the Jordan frame, in the cosmological epoch when the energy density of the ordinary dust matter dominates over the energy density of the scalar potential. Motivated by cosmological observations, we apply an approximation scheme in the regime close to the so-called limit of general relativity. The ensuing nonlinear approximate equations for the scalar field and the Hubble parameter can be solved analytically in cosmological time. This allows us to distinguish the theories with solutions that asymptotically converge to general relativity and draw some implications about the cosmological dynamics near this limit.
[ { "created": "Thu, 22 Dec 2011 13:50:43 GMT", "version": "v1" } ]
2015-06-03
[ [ "Järv", "Laur", "" ], [ "Kuusk", "Piret", "" ], [ "Saal", "Margus", "" ] ]
We consider flat Friedmann-Lema\^{\i}tre-Robertson-Walker cosmological models in the framework of general scalar-tensor theories of gravity with arbitrary coupling functions, set in the Jordan frame, in the cosmological epoch when the energy density of the ordinary dust matter dominates over the energy density of the scalar potential. Motivated by cosmological observations, we apply an approximation scheme in the regime close to the so-called limit of general relativity. The ensuing nonlinear approximate equations for the scalar field and the Hubble parameter can be solved analytically in cosmological time. This allows us to distinguish the theories with solutions that asymptotically converge to general relativity and draw some implications about the cosmological dynamics near this limit.
gr-qc/0204047
Kazuya Koyama
Kazuya Koyama
Radion and Large Scale Anisotropy on the Brane
Improved version to appear in PRD, Results and conclusions unchanged
Phys.Rev. D66 (2002) 084003
10.1103/PhysRevD.66.084003
UTAP-413
gr-qc astro-ph hep-th
null
We investigate the effect of the radion on cosmological perturbations in the brane world. The S^1/Z_2 compactified 5D Anti-de Sitter spacetime bounded by positive and negative tension branes is considered. The radion is the relative displacement of the branes in this model. We find two different kinds of the radion at the linear perturbation order for a cosmological brane. One describes a "fluctuation" of the brane which does not couple to matter on the brane. The other describes a "bend" of the brane which couples to the matter. The bend determines the curvature perturbation on the brane. At large scales, the radion interacts with anisotopic perturbations in the bulk. By solving the bulk anisotropic perturbations, large scale metric perturbations and anisotropies of the Cosmic Microwave Background (CMB) on the positive tension brane are calculated. We find an interesting fact that the radion contributes to the CMB anisotropies. The observational consequences of these effects are discussed.
[ { "created": "Sun, 14 Apr 2002 06:57:07 GMT", "version": "v1" }, { "created": "Fri, 26 Jul 2002 19:00:08 GMT", "version": "v2" } ]
2009-11-07
[ [ "Koyama", "Kazuya", "" ] ]
We investigate the effect of the radion on cosmological perturbations in the brane world. The S^1/Z_2 compactified 5D Anti-de Sitter spacetime bounded by positive and negative tension branes is considered. The radion is the relative displacement of the branes in this model. We find two different kinds of the radion at the linear perturbation order for a cosmological brane. One describes a "fluctuation" of the brane which does not couple to matter on the brane. The other describes a "bend" of the brane which couples to the matter. The bend determines the curvature perturbation on the brane. At large scales, the radion interacts with anisotopic perturbations in the bulk. By solving the bulk anisotropic perturbations, large scale metric perturbations and anisotropies of the Cosmic Microwave Background (CMB) on the positive tension brane are calculated. We find an interesting fact that the radion contributes to the CMB anisotropies. The observational consequences of these effects are discussed.
2304.12563
Torben Frost
Torben C. Frost
Gravitational Lensing of Massive Particles in the Charged NUT Spacetime
53 pages, 16 figures, extends parts of the work in arXiv:2112.10260 to massive particles
Phys. Rev. D 108, 124019 (2023)
10.1103/PhysRevD.108.124019
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In astronomy gravitational lensing of light leads to the formation of multiple images, arcs, Einstein rings, and, most important, the shadow of black holes. Analogously in the vicinity of a massive compact object massive particles, following timelike geodesics, are gravitationally lensed. So far gravitational lensing of massive particles was mainly investigated in the weak and strong field limits. In this paper we will, for the first time, investigate exact gravitational lensing of massive particles using the example of the charged NUT metric (and its special cases) which contains three physical parameters, the mass parameter $m$, the electric charge $e$, and the gravitomagnetic charge $n$. We will first discuss and solve the equations of motion for timelike geodesics using elementary and Jacobi's elliptic functions and Legendre's elliptic integrals. Then we will introduce an orthonormal tetrad to relate the $z$ component of the angular momentum and the Carter constant to the energy $E$ of the particles along the timelike geodesics and latitude-longitude coordinates on the celestial sphere of a stationary observer in the domain of outer communication. We will use these relations to derive the angular radius of the particle shadow of the black hole, to formulate an exact lens equation, and to derive the travel time of the particles in terms of the time coordinate and the proper time. Finally, we will discuss the impact of the physical parameters and the energy on observable lensing features.
[ { "created": "Tue, 25 Apr 2023 04:12:33 GMT", "version": "v1" } ]
2023-12-25
[ [ "Frost", "Torben C.", "" ] ]
In astronomy gravitational lensing of light leads to the formation of multiple images, arcs, Einstein rings, and, most important, the shadow of black holes. Analogously in the vicinity of a massive compact object massive particles, following timelike geodesics, are gravitationally lensed. So far gravitational lensing of massive particles was mainly investigated in the weak and strong field limits. In this paper we will, for the first time, investigate exact gravitational lensing of massive particles using the example of the charged NUT metric (and its special cases) which contains three physical parameters, the mass parameter $m$, the electric charge $e$, and the gravitomagnetic charge $n$. We will first discuss and solve the equations of motion for timelike geodesics using elementary and Jacobi's elliptic functions and Legendre's elliptic integrals. Then we will introduce an orthonormal tetrad to relate the $z$ component of the angular momentum and the Carter constant to the energy $E$ of the particles along the timelike geodesics and latitude-longitude coordinates on the celestial sphere of a stationary observer in the domain of outer communication. We will use these relations to derive the angular radius of the particle shadow of the black hole, to formulate an exact lens equation, and to derive the travel time of the particles in terms of the time coordinate and the proper time. Finally, we will discuss the impact of the physical parameters and the energy on observable lensing features.
2111.14475
Yakov Shnir
Carlos Herdeiro, Ilya Perapechka, Eugen Radu, and Yakov Shnir
Spinning gauged boson and Dirac stars: a comparative study
11 pages, 6 figures. Accepted in Phys. Lett. B
null
10.1016/j.physletb.2021.136811
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Scalar boson stars and Dirac stars are solitonic solutions of the Einstein{Klein-Gordon and Einstein- Dirac classical equations, respectively. Despite the different bosonic vs: fermionic nature of the matter field, these solutions to the classical field equations have been shown to have qualitatively similar features [1]. In particular, for spinning stars the most fundamental configurations can be in both cases toroidal, unlike spinning Proca stars that are spheroidal [2]. In this paper we gauge the scalar and Dirac fields, by minimally coupling them to standard electromagnetism. We explore the impact of the gauge coupling on the resulting solutions. One of the most relevant difference concerns the gyromagnetic ratio, which for the scalar stars takes values around 1, whereas for Dirac stars takes values around 2.
[ { "created": "Mon, 29 Nov 2021 11:41:33 GMT", "version": "v1" } ]
2022-01-05
[ [ "Herdeiro", "Carlos", "" ], [ "Perapechka", "Ilya", "" ], [ "Radu", "Eugen", "" ], [ "Shnir", "Yakov", "" ] ]
Scalar boson stars and Dirac stars are solitonic solutions of the Einstein{Klein-Gordon and Einstein- Dirac classical equations, respectively. Despite the different bosonic vs: fermionic nature of the matter field, these solutions to the classical field equations have been shown to have qualitatively similar features [1]. In particular, for spinning stars the most fundamental configurations can be in both cases toroidal, unlike spinning Proca stars that are spheroidal [2]. In this paper we gauge the scalar and Dirac fields, by minimally coupling them to standard electromagnetism. We explore the impact of the gauge coupling on the resulting solutions. One of the most relevant difference concerns the gyromagnetic ratio, which for the scalar stars takes values around 1, whereas for Dirac stars takes values around 2.
2211.06076
Konstantinos Dialektopoulos F.
Konstantinos F. Dialektopoulos, Jackson Levi Said, Zinovia Oikonomopoulou
Dynamical systems in Einstein Gauss-Bonnet gravity
14 pages, 13 figures
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this work we explore the dynamical system phase space of Einstein-Gauss-Bonnet theory in the cosmological minisuperspace. This approach binds the main features of the theory through a system of autonomous differential equations, in the context of a flat Friedmann-Lema\^{i}tre-Robertson-Walker spacetime. We analyze the critical points that feature in this system to assess their stability criteria. The phase space of this form of scalar-tensor gravity is very rich due to the fourth-order contributions of the Gauss-Bonnet invariant together with the second order contribution of the scalar field together with their coupling dynamics. We find additional critical points as compared with previous works in the literature which may be important for understanding the larger evolution of standard background cosmology within this class of gravitational models.
[ { "created": "Fri, 11 Nov 2022 09:14:34 GMT", "version": "v1" } ]
2022-11-14
[ [ "Dialektopoulos", "Konstantinos F.", "" ], [ "Said", "Jackson Levi", "" ], [ "Oikonomopoulou", "Zinovia", "" ] ]
In this work we explore the dynamical system phase space of Einstein-Gauss-Bonnet theory in the cosmological minisuperspace. This approach binds the main features of the theory through a system of autonomous differential equations, in the context of a flat Friedmann-Lema\^{i}tre-Robertson-Walker spacetime. We analyze the critical points that feature in this system to assess their stability criteria. The phase space of this form of scalar-tensor gravity is very rich due to the fourth-order contributions of the Gauss-Bonnet invariant together with the second order contribution of the scalar field together with their coupling dynamics. We find additional critical points as compared with previous works in the literature which may be important for understanding the larger evolution of standard background cosmology within this class of gravitational models.
gr-qc/0301049
B. S. Sathyaprakash
B.S. Sathyaprakash and B.F. Schutz (Cardiff University and MPI for Gravitational Physics)
Templates for stellar mass black holes falling into supermassive black holes
12 pages, 4 Tables, 4th LISA symposium, submitted to CQG
Class.Quant.Grav.20:S209-S218,2003
10.1088/0264-9381/20/10/324
null
gr-qc
null
The spin modulated gravitational wave signals, which we shall call smirches, emitted by stellar mass black holes tumbling and inspiralling into massive black holes have extremely complicated shapes. Tracking these signals with the aid of pattern matching techniques, such as Wiener filtering, is likely to be computationally an impossible exercise. In this article we propose using a mixture of optimal and non-optimal methods to create a search hierarchy to ease the computational burden. Furthermore, by employing the method of principal components (also known as singular value decomposition) we explicitly demonstrate that the effective dimensionality of the search parameter space of smirches is likely to be just three or four, much smaller than what has hitherto been thought to be about nine or ten. This result, based on a limited study of the parameter space, should be confirmed by a more exhaustive study over the parameter space as well as Monte-Carlo simulations to test the predictions made in this paper.
[ { "created": "Wed, 15 Jan 2003 13:13:59 GMT", "version": "v1" } ]
2009-11-10
[ [ "Sathyaprakash", "B. S.", "", "Cardiff University and MPI for\n Gravitational Physics" ], [ "Schutz", "B. F.", "", "Cardiff University and MPI for\n Gravitational Physics" ] ]
The spin modulated gravitational wave signals, which we shall call smirches, emitted by stellar mass black holes tumbling and inspiralling into massive black holes have extremely complicated shapes. Tracking these signals with the aid of pattern matching techniques, such as Wiener filtering, is likely to be computationally an impossible exercise. In this article we propose using a mixture of optimal and non-optimal methods to create a search hierarchy to ease the computational burden. Furthermore, by employing the method of principal components (also known as singular value decomposition) we explicitly demonstrate that the effective dimensionality of the search parameter space of smirches is likely to be just three or four, much smaller than what has hitherto been thought to be about nine or ten. This result, based on a limited study of the parameter space, should be confirmed by a more exhaustive study over the parameter space as well as Monte-Carlo simulations to test the predictions made in this paper.
1912.08225
Baofei Li
Bao-Fei Li, Parampreet Singh, Anzhong Wang
Primordial power spectrum from the dressed metric approach in loop cosmologies
Revised version with added discussion. References added. To appear in PRD
Phys. Rev. D 101, 086004 (2020)
10.1103/PhysRevD.101.086004
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We investigate the consequences of different regularizations and ambiguities in loop cosmological models on the predictions in the scalar and tensor primordial spectrum of the cosmic microwave background using the dressed metric approach. Three models, standard loop quantum cosmology (LQC), and two modified loop quantum cosmologies (mLQC-I and mLQC-II) arising from different regularizations of the Lorentzian term in the classical Hamiltonian constraint are explored for chaotic inflation in spatially-flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) universe. In each model, two different treatments of the conjugate momentum of the scale factor are considered. The first one corresponds to the conventional treatment in dressed metric approach, and the second one is inspired from the hybrid approach which uses the effective Hamiltonian constraint. For these two choices, we find the power spectrum to be scale-invariant in the ultra-violet regime for all three models, but there is at least a $10\%$ relative difference in amplitude in the infra-red and intermediate regimes. All three models result in significant differences in the latter regimes. In mLQC-I, the magnitude of the power spectrum in the infra-red regime is of the order of Planck scale irrespective of the ambiguity in conjugate momentum of the scale factor. The relative difference in the amplitude of the power spectrum between LQC and mLQC-II can be as large as $50\%$ throughout the infra-red and intermediate regimes. Differences in amplitude due to regularizations and ambiguities turn out to be small in the ultra-violet regime.
[ { "created": "Tue, 17 Dec 2019 19:02:58 GMT", "version": "v1" }, { "created": "Mon, 23 Dec 2019 19:48:30 GMT", "version": "v2" }, { "created": "Fri, 27 Mar 2020 21:20:13 GMT", "version": "v3" } ]
2020-04-08
[ [ "Li", "Bao-Fei", "" ], [ "Singh", "Parampreet", "" ], [ "Wang", "Anzhong", "" ] ]
We investigate the consequences of different regularizations and ambiguities in loop cosmological models on the predictions in the scalar and tensor primordial spectrum of the cosmic microwave background using the dressed metric approach. Three models, standard loop quantum cosmology (LQC), and two modified loop quantum cosmologies (mLQC-I and mLQC-II) arising from different regularizations of the Lorentzian term in the classical Hamiltonian constraint are explored for chaotic inflation in spatially-flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) universe. In each model, two different treatments of the conjugate momentum of the scale factor are considered. The first one corresponds to the conventional treatment in dressed metric approach, and the second one is inspired from the hybrid approach which uses the effective Hamiltonian constraint. For these two choices, we find the power spectrum to be scale-invariant in the ultra-violet regime for all three models, but there is at least a $10\%$ relative difference in amplitude in the infra-red and intermediate regimes. All three models result in significant differences in the latter regimes. In mLQC-I, the magnitude of the power spectrum in the infra-red regime is of the order of Planck scale irrespective of the ambiguity in conjugate momentum of the scale factor. The relative difference in the amplitude of the power spectrum between LQC and mLQC-II can be as large as $50\%$ throughout the infra-red and intermediate regimes. Differences in amplitude due to regularizations and ambiguities turn out to be small in the ultra-violet regime.
2302.11189
Xiangdong Zhang
Yongbin Du and Xiangdong Zhang
Topological classes of BTZ black holes
10 pages and 5 figures; v2, references updated
null
null
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
In the recent paper [Phys. Rev. Lett. 129, 191101 (2022)], the black holes were viewed as topological thermodynamic defects by using the generalized off-shell free energy. Their work indicates that all black hole solutions in the pure Einstein-Maxwell gravity theory could be classified into three different topological classes for four and higher spacetime dimensions. In this paper, we investigate the topological number of BTZ black holes with different charges $(Q)$ and rotational $(J)$ parameters. By using generalized free energy and Duan's $\phi$-mapping topological current theory, we interestingly found only two topological classes for BTZ spacetime. Particularly, for $Q=J=0$ BTZ black hole, there has only one zero point and therefore the total topological number is 1. While for rotating or charged cases, there are always two zero points and the global topological number is zero.
[ { "created": "Wed, 22 Feb 2023 07:52:21 GMT", "version": "v1" }, { "created": "Thu, 23 Feb 2023 03:59:05 GMT", "version": "v2" } ]
2023-02-24
[ [ "Du", "Yongbin", "" ], [ "Zhang", "Xiangdong", "" ] ]
In the recent paper [Phys. Rev. Lett. 129, 191101 (2022)], the black holes were viewed as topological thermodynamic defects by using the generalized off-shell free energy. Their work indicates that all black hole solutions in the pure Einstein-Maxwell gravity theory could be classified into three different topological classes for four and higher spacetime dimensions. In this paper, we investigate the topological number of BTZ black holes with different charges $(Q)$ and rotational $(J)$ parameters. By using generalized free energy and Duan's $\phi$-mapping topological current theory, we interestingly found only two topological classes for BTZ spacetime. Particularly, for $Q=J=0$ BTZ black hole, there has only one zero point and therefore the total topological number is 1. While for rotating or charged cases, there are always two zero points and the global topological number is zero.
1805.03467
Diego S\'aez-Chill\'on G\'omez
Yi Zhong and Diego Saez-Chillon Gomez
Inflation in mimetic f(G) gravity
14 pages, 2 figures
Symmetry 2018, 10(5), 170
10.3390/sym10050170
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Mimetic gravity is analysed in the framework of some extensions of General Relativity, where a function of the Gauss-Bonnet invariant in four dimensions is considered. By assuming the so-called mimetic condition, the conformal degree of freedom is isolated and a pressureless fluid naturally arises. Then, the complete set of field equations for mimetic Gauss-Bonnet gravity is established and some inflationary models are analysed, for which the corresponding gravitational action is reconstructed. The spectral index and tensor-to-scalar ratio are obtained and compared with observational bounds from Planck and BICEP2/Keck array data. The full agreement with above data is achieved for several versions of the mimetic Gauss-Bonnet gravity. Finally, some extensions of Gauss-Bonnet mimetic gravity are considered and the possibility of reproducing inflation is also explored.
[ { "created": "Wed, 9 May 2018 12:10:26 GMT", "version": "v1" } ]
2018-05-22
[ [ "Zhong", "Yi", "" ], [ "Gomez", "Diego Saez-Chillon", "" ] ]
Mimetic gravity is analysed in the framework of some extensions of General Relativity, where a function of the Gauss-Bonnet invariant in four dimensions is considered. By assuming the so-called mimetic condition, the conformal degree of freedom is isolated and a pressureless fluid naturally arises. Then, the complete set of field equations for mimetic Gauss-Bonnet gravity is established and some inflationary models are analysed, for which the corresponding gravitational action is reconstructed. The spectral index and tensor-to-scalar ratio are obtained and compared with observational bounds from Planck and BICEP2/Keck array data. The full agreement with above data is achieved for several versions of the mimetic Gauss-Bonnet gravity. Finally, some extensions of Gauss-Bonnet mimetic gravity are considered and the possibility of reproducing inflation is also explored.
1201.4226
Iosif Khriplovich
I. B. Khriplovich
Gravitational four-fermion interaction on the Planck scale
4 pages, few comments added
null
10.1016/j.physletb.2012.01.072
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The four-fermion gravitational interaction is induced by torsion, and gets essential on the Planck scale. On this scale, the axial-axial contribution dominates strongly in the discussed interaction. The energy-momentum tensor, generated by this contribution, is analyzed, as well as stability of the problem with respect to compression. The trace of this energy-momentum tensor can be negative.
[ { "created": "Fri, 20 Jan 2012 08:18:58 GMT", "version": "v1" }, { "created": "Wed, 1 Feb 2012 08:00:36 GMT", "version": "v2" } ]
2015-06-03
[ [ "Khriplovich", "I. B.", "" ] ]
The four-fermion gravitational interaction is induced by torsion, and gets essential on the Planck scale. On this scale, the axial-axial contribution dominates strongly in the discussed interaction. The energy-momentum tensor, generated by this contribution, is analyzed, as well as stability of the problem with respect to compression. The trace of this energy-momentum tensor can be negative.
2112.13198
Kirill Bronnikov
Kirill A. Bronnikov, Rahul Kumar Walia
Field sources for Simpson-Visser space-times
null
Phys. Rev. D 15, 044039 (2022)
10.1103/PhysRevD.105.044039
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Simpson-Visser (SV) space-times are the simplest globally regular modifications of the Schwarzschild, Reissner-Nordstrom and other blak-hole solutions of general relativity. They smoothly interpolate between these black holes and traversable wormholes. After a brief presentation of the Schwarzschild-like and Reissner-Nordstrom-like SV geometries, including their Carter-Penrose diagrams, we show that any static, spherically symmetric SV metric can be obtained as an exact solution to the Einstein field equations sourced by a combination of a minimally coupled phantom scalar field with a nonzero potential $V(\phi)$ and a magnetic field in the framework of nonlinear electrodynamics with the Lagrangian $\mathcal {L(F)}$, $\mathcal{F} = F_{\mu\nu} F^{\mu\nu}$ (in standard notations). Explicit forms of $V(\phi)$ and $\mathcal {L(F)}$ are presented for the cases of Schwarzschild-like and Reissner-Nordstrom-like SV metrics.
[ { "created": "Sat, 25 Dec 2021 07:26:39 GMT", "version": "v1" } ]
2022-09-16
[ [ "Bronnikov", "Kirill A.", "" ], [ "Walia", "Rahul Kumar", "" ] ]
Simpson-Visser (SV) space-times are the simplest globally regular modifications of the Schwarzschild, Reissner-Nordstrom and other blak-hole solutions of general relativity. They smoothly interpolate between these black holes and traversable wormholes. After a brief presentation of the Schwarzschild-like and Reissner-Nordstrom-like SV geometries, including their Carter-Penrose diagrams, we show that any static, spherically symmetric SV metric can be obtained as an exact solution to the Einstein field equations sourced by a combination of a minimally coupled phantom scalar field with a nonzero potential $V(\phi)$ and a magnetic field in the framework of nonlinear electrodynamics with the Lagrangian $\mathcal {L(F)}$, $\mathcal{F} = F_{\mu\nu} F^{\mu\nu}$ (in standard notations). Explicit forms of $V(\phi)$ and $\mathcal {L(F)}$ are presented for the cases of Schwarzschild-like and Reissner-Nordstrom-like SV metrics.
gr-qc/9411023
null
Bruce Allen
Maximally Symmetric Spin-Two Bitensors on $S^3$ and $H^3$
12 pages, RevTeX, uuencoded compressed .tex file, minor typos corrected
Phys.Rev. D51 (1995) 5491-5497
10.1103/PhysRevD.51.5491
WISC-MILW-94-TH-25
gr-qc
null
The transverse traceless spin-two tensor harmonics on $S^3$ and $H^3$ may be denoted by $T^{(kl)}{}_{ab}$. The index $k$ labels the (degenerate) eigenvalues of the Laplacian $\square$ and $l$ the other indices. We compute the bitensor $\sum_l T^{(kl)}{}_{ab}(x) T^{(kl)}{}_{a'b'}(x')^*$ where $x,x'$ are distinct points on a sphere or hyperboloid of unit radius. These quantities may be used to find the correlation function of a stochastic background of gravitational waves in spatially open or closed Friedman-Robertson-Walker cosmologies.
[ { "created": "Tue, 8 Nov 1994 18:46:00 GMT", "version": "v1" }, { "created": "Wed, 16 Nov 1994 15:25:00 GMT", "version": "v2" } ]
2009-10-22
[ [ "Allen", "Bruce", "" ] ]
The transverse traceless spin-two tensor harmonics on $S^3$ and $H^3$ may be denoted by $T^{(kl)}{}_{ab}$. The index $k$ labels the (degenerate) eigenvalues of the Laplacian $\square$ and $l$ the other indices. We compute the bitensor $\sum_l T^{(kl)}{}_{ab}(x) T^{(kl)}{}_{a'b'}(x')^*$ where $x,x'$ are distinct points on a sphere or hyperboloid of unit radius. These quantities may be used to find the correlation function of a stochastic background of gravitational waves in spatially open or closed Friedman-Robertson-Walker cosmologies.
0906.0235
Branislav Cvetkovi\'c
M. Blagojevi\'c, B. Cvetkovi\'c and O. Miskovi\'c
Nonlinear electrodynamics in 3D gravity with torsion
LATEX, 16 pages, v2: minor corrections
Phys.Rev.D80:024043,2009
10.1103/PhysRevD.80.024043
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study exact solutions of nonlinear electrodynamics coupled to three-dimensional gravity with torsion. We show that in any static and spherically symmetric configuration, at least one component of the electromagnetic field has to vanish. In the electric sector of the theory, we construct an exact solution, characterized by the azimuthal electric field. When the electromagnetic action is modified by a topological mass term, we find two types of the self-dual solutions.
[ { "created": "Mon, 1 Jun 2009 08:29:19 GMT", "version": "v1" }, { "created": "Fri, 7 Aug 2009 22:46:44 GMT", "version": "v2" } ]
2009-09-02
[ [ "Blagojević", "M.", "" ], [ "Cvetković", "B.", "" ], [ "Misković", "O.", "" ] ]
We study exact solutions of nonlinear electrodynamics coupled to three-dimensional gravity with torsion. We show that in any static and spherically symmetric configuration, at least one component of the electromagnetic field has to vanish. In the electric sector of the theory, we construct an exact solution, characterized by the azimuthal electric field. When the electromagnetic action is modified by a topological mass term, we find two types of the self-dual solutions.
2403.08387
Fech Scen Khoo
Bahareh Azad, Jose Luis Bl\'azquez-Salcedo, Fech Scen Khoo, Jutta Kunz
Radial perturbations of Ellis-Bronnikov wormholes in slow rotation up to second order
27 pages, 8 figures
Phys. Rev. D 109, 124051 (2024)
10.1103/PhysRevD.109.124051
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider slowly rotating Ellis-Bronnikov wormholes and investigate their radial perturbations ($\mathrm{l}=0$), expanding up to second order in rotation. We present the detailed derivations in the general case, including symmetric and non-symmetric wormholes. The calculations show that the unstable mode present in the static case becomes less unstable with increasing rotation, until it reaches zero and then disappears. This indicates that wormhole solutions may become linearly mode stable at sufficiently fast rotation.
[ { "created": "Wed, 13 Mar 2024 09:53:21 GMT", "version": "v1" } ]
2024-06-25
[ [ "Azad", "Bahareh", "" ], [ "Blázquez-Salcedo", "Jose Luis", "" ], [ "Khoo", "Fech Scen", "" ], [ "Kunz", "Jutta", "" ] ]
We consider slowly rotating Ellis-Bronnikov wormholes and investigate their radial perturbations ($\mathrm{l}=0$), expanding up to second order in rotation. We present the detailed derivations in the general case, including symmetric and non-symmetric wormholes. The calculations show that the unstable mode present in the static case becomes less unstable with increasing rotation, until it reaches zero and then disappears. This indicates that wormhole solutions may become linearly mode stable at sufficiently fast rotation.
1804.06730
Richard Petti
R. J. Petti
Translational Spacetime Symmetries in Gravitational Theories
16 pages, 1 table, 1 figure. Published in Classical and Quantum Gravity, 23 (2006) p 737-751. This version makes two changes to the version published in Class. Quantum Grav. (1) It corrects equation (10) in section 2.7 by including a term that was omitted. (2) It has a a table of contents at the end that was not included in Class. Quantum Grav
Class. Quantum Grav. 23 (2006) 737-751
10.1088/0264-9381/23/3/012
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
How to include spacetime translations in fibre bundle gauge theories has been a subject of controversy, because spacetime symmetries are not internal symmetries of the bundle structure group. The standard method for including affine symmetry in differential geometry is to define a Cartan connection on an affine bundle over spacetime. This is equivalent to (1) defining an affine connection on the affine bundle, (2) defining a zero section on the associated affine vector bundle, and (3) using the affine connection and the zero section to define an "associated solder form," whose lift to a tensorial form on the frame bundle becomes the solder form. The zero section reduces the affine bundle to a linear bundle and splits the affine connection into translational and homogeneous parts; however it violates translational equivariance / gauge symmetry. This is the natural geometric framework for Einstein-Cartan theory as an affine theory of gravitation. The last section discusses some alternative approaches that claim to preserve translational gauge symmetry.
[ { "created": "Mon, 16 Apr 2018 18:24:18 GMT", "version": "v1" } ]
2018-04-25
[ [ "Petti", "R. J.", "" ] ]
How to include spacetime translations in fibre bundle gauge theories has been a subject of controversy, because spacetime symmetries are not internal symmetries of the bundle structure group. The standard method for including affine symmetry in differential geometry is to define a Cartan connection on an affine bundle over spacetime. This is equivalent to (1) defining an affine connection on the affine bundle, (2) defining a zero section on the associated affine vector bundle, and (3) using the affine connection and the zero section to define an "associated solder form," whose lift to a tensorial form on the frame bundle becomes the solder form. The zero section reduces the affine bundle to a linear bundle and splits the affine connection into translational and homogeneous parts; however it violates translational equivariance / gauge symmetry. This is the natural geometric framework for Einstein-Cartan theory as an affine theory of gravitation. The last section discusses some alternative approaches that claim to preserve translational gauge symmetry.
gr-qc/9611028
Jose Acacio de Barros
J. Acacio de Barros (Physics Department/UFJF, Brazil) and N. Pinto-Neto (CBPF/Lafex, Brazil)
The Causal Interpretation of Quantum Mechanics and The Singularity Problem in Quantum Cosmology
18 pages, LaTeX
Nucl.Phys.Proc.Suppl. 57 (1997) 247-250
10.1016/S0920-5632(97)00396-4
null
gr-qc quant-ph
null
We apply the causal interpretation of quantum mechanics to homogeneous quantum cosmology and show that the quantum theory is independent of any time-gauge choice and there is no issue of time. We exemplify this result by studying a particular minisuperspace model where the quantum potential driven by a prescribed quantum state prevents the formation of the classical singularity, independently on the choice of the lapse function. This means that the fast-slow-time gauge conjecture is irrelevant within the framework of the causal interpretation of quantum cosmology.
[ { "created": "Mon, 11 Nov 1996 19:05:53 GMT", "version": "v1" } ]
2015-06-25
[ [ "de Barros", "J. Acacio", "", "Physics Department/UFJF, Brazil" ], [ "Pinto-Neto", "N.", "", "CBPF/Lafex, Brazil" ] ]
We apply the causal interpretation of quantum mechanics to homogeneous quantum cosmology and show that the quantum theory is independent of any time-gauge choice and there is no issue of time. We exemplify this result by studying a particular minisuperspace model where the quantum potential driven by a prescribed quantum state prevents the formation of the classical singularity, independently on the choice of the lapse function. This means that the fast-slow-time gauge conjecture is irrelevant within the framework of the causal interpretation of quantum cosmology.
1209.6324
Nikolai V. Mitskievich
Nikolai V. Mitskievich
On eternal black holes and some interior solutions
19 pages, no figures
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this article we deduce two new exact solutions of Einstein's equations for eternal black holes, now related to stiff matter, one `static' and another rotating (stationary like the Kerr one), thus the number of these eternal solutions grows from four to six. Dealing with these static and rotating solutions we automatically rehabilitate the practically forgotten Sommerfeld-Lenz approach to the deduction of our results for the satisfaction of Einstein's equations, e.g., in these rotating cases. At the same time, we come to the confirmation of our new relativistic generalization of the inertial/gravitational mass equivalence principle, as well as to obtention of the Kerr interior solution.
[ { "created": "Thu, 27 Sep 2012 18:33:29 GMT", "version": "v1" }, { "created": "Mon, 15 Oct 2012 17:54:47 GMT", "version": "v2" }, { "created": "Thu, 18 Oct 2012 19:56:13 GMT", "version": "v3" } ]
2012-10-19
[ [ "Mitskievich", "Nikolai V.", "" ] ]
In this article we deduce two new exact solutions of Einstein's equations for eternal black holes, now related to stiff matter, one `static' and another rotating (stationary like the Kerr one), thus the number of these eternal solutions grows from four to six. Dealing with these static and rotating solutions we automatically rehabilitate the practically forgotten Sommerfeld-Lenz approach to the deduction of our results for the satisfaction of Einstein's equations, e.g., in these rotating cases. At the same time, we come to the confirmation of our new relativistic generalization of the inertial/gravitational mass equivalence principle, as well as to obtention of the Kerr interior solution.
gr-qc/9811090
Pierre Teyssandier
C. Bracco and P. Teyssandier
Scintillation in scalar-tensor theories of gravity
8 pages; to appear in Astronomy and Astrophysics
null
null
null
gr-qc
null
We study the scintillation produced by time-varying gravitational fields within scalar-tensor theories of gravity. The problem is treated in the geometrical optics approximation for a very distant light source emitting quasi plane monochromatic electromagnetic waves. We obtain a general formula giving the time dependence of the photon flux received by a freely falling observer. In the weak-field approximation, we show that the contribution to the scintillation effect due to the focusing of the light beam by a gravitational wave is of first order in the amplitude of the scalar perturbation. Thus scalar-tensor theories contrast with general relativity, which predicts that the only first-order effect is due to the spectral shift. Moreover, we find that the scintillation effects caused by the scalar field have a local character: they depend only on the value of the perturbation at the observer. This effect provides in principle a mean to detect the presence of a long range scalar field in the Universe, but its smallness constitutes a tremendous challenge for detection.
[ { "created": "Thu, 26 Nov 1998 17:09:51 GMT", "version": "v1" } ]
2007-05-23
[ [ "Bracco", "C.", "" ], [ "Teyssandier", "P.", "" ] ]
We study the scintillation produced by time-varying gravitational fields within scalar-tensor theories of gravity. The problem is treated in the geometrical optics approximation for a very distant light source emitting quasi plane monochromatic electromagnetic waves. We obtain a general formula giving the time dependence of the photon flux received by a freely falling observer. In the weak-field approximation, we show that the contribution to the scintillation effect due to the focusing of the light beam by a gravitational wave is of first order in the amplitude of the scalar perturbation. Thus scalar-tensor theories contrast with general relativity, which predicts that the only first-order effect is due to the spectral shift. Moreover, we find that the scintillation effects caused by the scalar field have a local character: they depend only on the value of the perturbation at the observer. This effect provides in principle a mean to detect the presence of a long range scalar field in the Universe, but its smallness constitutes a tremendous challenge for detection.
1709.06494
Ettore Minguzzi
E. Minguzzi
Causality theory for closed cone structures with applications
Latex2e, 138 pages. Work presented at the meetings "Non-regular spacetime geometry", Firenze, June 20-22, 2017, and "Advances in General Relativity", ESI Vienna, August 28 - September 1, 2017. v3: added distance formula for stably causal (rather than just stable) spacetimes. v4: Added a few regularity results, final version
Rev. Math. Phys. 31 (2019) 1930001
10.1142/S0129055X19300012
null
gr-qc math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We develop causality theory for upper semi-continuous distributions of cones over manifolds generalizing results from mathematical relativity in two directions: non-round cones and non-regular differentiability assumptions. We prove the validity of most results of the regular Lorentzian causality theory including causal ladder, Fermat's principle, notable singularity theorems in their causal formulation, Avez-Seifert theorem, characterizations of stable causality and global hyperbolicity by means of (smooth) time functions. For instance, we give the first proof for these structures of the equivalence between stable causality, $K$-causality and existence of a time function. The result implies that closed cone structures that admit continuous increasing functions also admit smooth ones. We also study proper cone structures, the fiber bundle analog of proper cones. For them we obtain most results on domains of dependence. Moreover, we prove that horismos and Cauchy horizons are generated by lightlike geodesics, the latter being defined through the achronality property. Causal geodesics and steep temporal functions are obtained with a powerful product trick. The paper also contains a study of Lorentz-Minkowski spaces under very weak regularity conditions. Finally, we introduce the concepts of stable distance and stable spacetime solving two well known problems (a) the characterization of Lorentzian manifolds embeddable in Minkowski spacetime, they turn out to be the stable spacetimes, (b) the proof that topology, order and distance (with a formula a la Connes) can be represented by the smooth steep temporal functions. The paper is self-contained, in fact we do not use any advanced result from mathematical relativity.
[ { "created": "Tue, 19 Sep 2017 15:55:38 GMT", "version": "v1" }, { "created": "Mon, 25 Sep 2017 21:17:45 GMT", "version": "v2" }, { "created": "Sat, 28 Oct 2017 13:55:27 GMT", "version": "v3" }, { "created": "Thu, 6 Dec 2018 19:05:43 GMT", "version": "v4" } ]
2019-03-06
[ [ "Minguzzi", "E.", "" ] ]
We develop causality theory for upper semi-continuous distributions of cones over manifolds generalizing results from mathematical relativity in two directions: non-round cones and non-regular differentiability assumptions. We prove the validity of most results of the regular Lorentzian causality theory including causal ladder, Fermat's principle, notable singularity theorems in their causal formulation, Avez-Seifert theorem, characterizations of stable causality and global hyperbolicity by means of (smooth) time functions. For instance, we give the first proof for these structures of the equivalence between stable causality, $K$-causality and existence of a time function. The result implies that closed cone structures that admit continuous increasing functions also admit smooth ones. We also study proper cone structures, the fiber bundle analog of proper cones. For them we obtain most results on domains of dependence. Moreover, we prove that horismos and Cauchy horizons are generated by lightlike geodesics, the latter being defined through the achronality property. Causal geodesics and steep temporal functions are obtained with a powerful product trick. The paper also contains a study of Lorentz-Minkowski spaces under very weak regularity conditions. Finally, we introduce the concepts of stable distance and stable spacetime solving two well known problems (a) the characterization of Lorentzian manifolds embeddable in Minkowski spacetime, they turn out to be the stable spacetimes, (b) the proof that topology, order and distance (with a formula a la Connes) can be represented by the smooth steep temporal functions. The paper is self-contained, in fact we do not use any advanced result from mathematical relativity.
1504.04223
Rong-Jia Yang
Rong-Jia Yang
Quantum gravity corrections to accretion onto a Schwarzschild black hole
7 pages
Phys. Rev. D 92, 084011 (2015)
10.1103/PhysRevD.92.084011
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Quantum gravity corrections to accretion onto a Schwarzschild black hole are considered in the context of asymptotically safe scenario. The possible positions of the critical points are discussed and the general conditions for critical points are obtained. The explicit expressions for matter density compression and temperature profile both below the critical radius and at the event horizon are derived. For polytropic matter, we determine the corrected temperature and the integrated flux resulting from quantum gravity effects at the event horizon, which might be as a test of asymptotically safe scenario.
[ { "created": "Thu, 16 Apr 2015 13:24:18 GMT", "version": "v1" }, { "created": "Mon, 19 Oct 2015 02:16:31 GMT", "version": "v2" } ]
2015-10-20
[ [ "Yang", "Rong-Jia", "" ] ]
Quantum gravity corrections to accretion onto a Schwarzschild black hole are considered in the context of asymptotically safe scenario. The possible positions of the critical points are discussed and the general conditions for critical points are obtained. The explicit expressions for matter density compression and temperature profile both below the critical radius and at the event horizon are derived. For polytropic matter, we determine the corrected temperature and the integrated flux resulting from quantum gravity effects at the event horizon, which might be as a test of asymptotically safe scenario.
gr-qc/9412024
Thibault Damour
T. Damour
General relativity and experiment
13 pages, LATEX
null
null
IHES/P/94/56
gr-qc
null
The confrontation between Einstein's theory of gravitation and experiment is summarized. Although all current experimental data are compatible with general relativity, the importance of pursuing the quest for possible deviations from Einstein's theory is emphasized.
[ { "created": "Thu, 8 Dec 1994 13:45:28 GMT", "version": "v1" } ]
2007-05-23
[ [ "Damour", "T.", "" ] ]
The confrontation between Einstein's theory of gravitation and experiment is summarized. Although all current experimental data are compatible with general relativity, the importance of pursuing the quest for possible deviations from Einstein's theory is emphasized.
2204.05054
Keisuke Nakashi
Keisuke Nakashi, Masashi Kimura, Hayato Motohashi, and Kazufumi Takahashi
Black hole perturbations in higher-order scalar-tensor theories: initial value problem and dynamical stability
35 pages, 13 figures, v2: published version in CQG
Class. Quant. Grav. 39 (2022) no.17, 175003
10.1088/1361-6382/ac813e
RUP-22-4, YITP-22-13
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
We propose a physically sensible formulation of initial value problem for black hole perturbations in higher-order scalar-tensor theories. As a first application, we study monopole perturbations around stealth Schwarzschild solutions in a shift- and reflection-symmetric subclass of degenerate higher-order scalar-tensor (DHOST) theories. In particular, we investigate the time evolution of the monopole perturbations by solving a two-dimensional wave equation and analyze the Vishveshwara's classical scattering experiment, i.e., the time evolution of a Gaussian wave packet. As a result, we confirm that stealth Schwarzschild solutions in the DHOST theory are dynamically stable against the monopole perturbations with the wavelength comparable or shorter than the size of the black hole horizon. We also find that the damped oscillations at the late time do not show up unlike the ringdown phase in the standard case of general relativity. Moreover, we investigate the characteristic curves of the monopole perturbations as well as a static spherically symmetric solution with monopole hair.
[ { "created": "Mon, 11 Apr 2022 12:46:41 GMT", "version": "v1" }, { "created": "Thu, 28 Jul 2022 02:13:15 GMT", "version": "v2" } ]
2022-08-19
[ [ "Nakashi", "Keisuke", "" ], [ "Kimura", "Masashi", "" ], [ "Motohashi", "Hayato", "" ], [ "Takahashi", "Kazufumi", "" ] ]
We propose a physically sensible formulation of initial value problem for black hole perturbations in higher-order scalar-tensor theories. As a first application, we study monopole perturbations around stealth Schwarzschild solutions in a shift- and reflection-symmetric subclass of degenerate higher-order scalar-tensor (DHOST) theories. In particular, we investigate the time evolution of the monopole perturbations by solving a two-dimensional wave equation and analyze the Vishveshwara's classical scattering experiment, i.e., the time evolution of a Gaussian wave packet. As a result, we confirm that stealth Schwarzschild solutions in the DHOST theory are dynamically stable against the monopole perturbations with the wavelength comparable or shorter than the size of the black hole horizon. We also find that the damped oscillations at the late time do not show up unlike the ringdown phase in the standard case of general relativity. Moreover, we investigate the characteristic curves of the monopole perturbations as well as a static spherically symmetric solution with monopole hair.
gr-qc/9710134
Benjamin J. Owen
Benjamin J. Owen (Caltech), Hideyuki Tagoshi (National Astronomical Observatory, Mitaka, Japan), Akira Ohashi (Kyoto University)
Non-precessional spin-orbit effects on gravitational waves from inspiraling compact binaries to second post-Newtonian order
11 pages, submitted to Phys. Rev. D
Phys.Rev. D57 (1998) 6168-6175
10.1103/PhysRevD.57.6168
null
gr-qc
null
We derive all second post-Newtonian (2PN), non-precessional effects of spin- orbit coupling on the gravitational wave forms emitted by an inspiraling binary composed of spinning, compact bodies in a quasicircular orbit. Previous post- Newtonian calculations of spin-orbit effects (at 1.5PN order) relied on a fluid description of the spinning bodies. We simplify the calculations by introducing into post-Newtonian theory a delta-function description of the influence of the spins on the bodies' energy-momentum tensor. This description was recently used by Mino, Shibata, and Tanaka (MST) in Teukolsky-formalism analyses of particles orbiting massive black holes, and is based on prior work by Dixon. We compute the 2PN contributions to the wave forms by combining the MST energy-momentum tensor with the formalism of Blanchet, Damour, and Iyer for evaluating the binary's radiative multipoles, and with the well-known 1.5PN order equations of motion for the binary. Our results contribute at 2PN order only to the amplitudes of the wave forms. The secular evolution of the wave forms' phase, the quantity most accurately measurable by LIGO, is not affected by our results until 2.5PN order, at which point other spin-orbit effects also come into play. We plan to evaluate the entire 2.5PN spin-orbit contribution to the secular phase evolution in a future paper, using the techniques of this paper.
[ { "created": "Fri, 31 Oct 1997 00:04:27 GMT", "version": "v1" } ]
2009-10-30
[ [ "Owen", "Benjamin J.", "", "Caltech" ], [ "Tagoshi", "Hideyuki", "", "National Astronomical\n Observatory, Mitaka, Japan" ], [ "Ohashi", "Akira", "", "Kyoto University" ] ]
We derive all second post-Newtonian (2PN), non-precessional effects of spin- orbit coupling on the gravitational wave forms emitted by an inspiraling binary composed of spinning, compact bodies in a quasicircular orbit. Previous post- Newtonian calculations of spin-orbit effects (at 1.5PN order) relied on a fluid description of the spinning bodies. We simplify the calculations by introducing into post-Newtonian theory a delta-function description of the influence of the spins on the bodies' energy-momentum tensor. This description was recently used by Mino, Shibata, and Tanaka (MST) in Teukolsky-formalism analyses of particles orbiting massive black holes, and is based on prior work by Dixon. We compute the 2PN contributions to the wave forms by combining the MST energy-momentum tensor with the formalism of Blanchet, Damour, and Iyer for evaluating the binary's radiative multipoles, and with the well-known 1.5PN order equations of motion for the binary. Our results contribute at 2PN order only to the amplitudes of the wave forms. The secular evolution of the wave forms' phase, the quantity most accurately measurable by LIGO, is not affected by our results until 2.5PN order, at which point other spin-orbit effects also come into play. We plan to evaluate the entire 2.5PN spin-orbit contribution to the secular phase evolution in a future paper, using the techniques of this paper.
gr-qc/0007051
Luc Blanchet
Luc Blanchet, Guillaume Faye
General relativistic dynamics of compact binaries at the third post-Newtonian order
78 pages, submitted to Phys. Rev. D, with minor modifications
Phys.Rev.D63:062005,2001
10.1103/PhysRevD.63.062005
null
gr-qc
null
The general relativistic corrections in the equations of motion and associated energy of a binary system of point-like masses are derived at the third post-Newtonian (3PN) order. The derivation is based on a post-Newtonian expansion of the metric in harmonic coordinates at the 3PN approximation. The metric is parametrized by appropriate non-linear potentials, which are evaluated in the case of two point-particles using a Lorentzian version of an Hadamard regularization which has been defined in previous works. Distributional forms and distributional derivatives constructed from this regularization are employed systematically. The equations of motion of the particles are geodesic-like with respect to the regularized metric. Crucial contributions to the acceleration are associated with the non-distributivity of the Hadamard regularization and the violation of the Leibniz rule by the distributional derivative. The final equations of motion at the 3PN order are invariant under global Lorentz transformations, and admit a conserved energy (neglecting the radiation reaction force at the 2.5PN order). However, they are not fully determined, as they depend on one arbitrary constant, which reflects probably a physical incompleteness of the point-mass regularization. The results of this paper should be useful when comparing theory to the observations of gravitational waves from binary systems in future detectors VIRGO and LIGO.
[ { "created": "Thu, 20 Jul 2000 17:08:13 GMT", "version": "v1" }, { "created": "Sat, 18 Nov 2000 19:43:52 GMT", "version": "v2" } ]
2009-12-31
[ [ "Blanchet", "Luc", "" ], [ "Faye", "Guillaume", "" ] ]
The general relativistic corrections in the equations of motion and associated energy of a binary system of point-like masses are derived at the third post-Newtonian (3PN) order. The derivation is based on a post-Newtonian expansion of the metric in harmonic coordinates at the 3PN approximation. The metric is parametrized by appropriate non-linear potentials, which are evaluated in the case of two point-particles using a Lorentzian version of an Hadamard regularization which has been defined in previous works. Distributional forms and distributional derivatives constructed from this regularization are employed systematically. The equations of motion of the particles are geodesic-like with respect to the regularized metric. Crucial contributions to the acceleration are associated with the non-distributivity of the Hadamard regularization and the violation of the Leibniz rule by the distributional derivative. The final equations of motion at the 3PN order are invariant under global Lorentz transformations, and admit a conserved energy (neglecting the radiation reaction force at the 2.5PN order). However, they are not fully determined, as they depend on one arbitrary constant, which reflects probably a physical incompleteness of the point-mass regularization. The results of this paper should be useful when comparing theory to the observations of gravitational waves from binary systems in future detectors VIRGO and LIGO.
1905.10767
Farrukh Fattoyev Jabborovich
F. J. Fattoyev
Neutron stars in general relativity and scalar-tensor theory of gravity
32 pages, 1 figure, 1 table; Manuscript published in final form in "Arabian Journal of Mathematics", July 11, 2019
Arabian Journal of Mathematics, July 11, 2019
10.1007/s40065-019-0265-5
null
gr-qc astro-ph.HE nucl-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The masses and radii of neutron stars are discussed in general relativity and scalar-tensor theory of gravity and the differences are compared with the current uncertainties stemming from the nuclear equation of state in the relativistic mean-field framework. It is shown that astrophysical and gravitational waves observations of radii of neutron stars with masses $M \lesssim 1.4 M_{\odot}$ constrain only the nuclear equation of state, and in particular the density dependence of the nuclear symmetry energy. Future observations of massive neutron stars may constrain the coupling parameters of the scalar-tensor theory provided that a general consensus on the dense nuclear matter equation of state is reached.
[ { "created": "Sun, 26 May 2019 09:08:52 GMT", "version": "v1" }, { "created": "Sun, 14 Jul 2019 04:21:31 GMT", "version": "v2" } ]
2019-07-16
[ [ "Fattoyev", "F. J.", "" ] ]
The masses and radii of neutron stars are discussed in general relativity and scalar-tensor theory of gravity and the differences are compared with the current uncertainties stemming from the nuclear equation of state in the relativistic mean-field framework. It is shown that astrophysical and gravitational waves observations of radii of neutron stars with masses $M \lesssim 1.4 M_{\odot}$ constrain only the nuclear equation of state, and in particular the density dependence of the nuclear symmetry energy. Future observations of massive neutron stars may constrain the coupling parameters of the scalar-tensor theory provided that a general consensus on the dense nuclear matter equation of state is reached.