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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1101.3955 | Marc Diaz-Aguilo Mr. | Marc Diaz-Aguilo, Alberto Lobo and Enrique Garc\'ia-Berro | Neural network interpolation of the magnetic field for the LISA
Pathfinder Diagnostics Subsystem | null | Exper.Astron.30:1-21,2011 | 10.1007/s10686-011-9215-8 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | LISA Pathfinder is a science and technology demonstrator of the European
Space Agency within the framework of its LISA mission, which aims to be the
first space-borne gravitational wave observatory. The payload of LISA
Pathfinder is the so-called LISA Technology Package, which is designed to
measure relative accelerations between two test masses in nominal free fall.
Its disturbances are monitored and dealt by the diagnostics subsystem. This
subsystem consists of several modules, and one of these is the magnetic
diagnostics system, which includes a set of four tri-axial fluxgate
magnetometers, intended to measure with high precision the magnetic field at
the positions of the test masses. However, since the magnetometers are located
far from the positions of the test masses, the magnetic field at their
positions must be interpolated. It has been recently shown that because there
are not enough magnetic channels, classical interpolation methods fail to
derive reliable measurements at the positions of the test masses, while neural
network interpolation can provide the required measurements at the desired
accuracy. In this paper we expand these studies and we assess the reliability
and robustness of the neural network interpolation scheme for variations of the
locations and possible offsets of the magnetometers, as well as for changes in
environmental conditions. We find that neural networks are robust enough to
derive accurate measurements of the magnetic field at the positions of the test
masses in most circumstances.
| [
{
"created": "Thu, 20 Jan 2011 16:42:58 GMT",
"version": "v1"
}
] | 2015-03-17 | [
[
"Diaz-Aguilo",
"Marc",
""
],
[
"Lobo",
"Alberto",
""
],
[
"García-Berro",
"Enrique",
""
]
] | LISA Pathfinder is a science and technology demonstrator of the European Space Agency within the framework of its LISA mission, which aims to be the first space-borne gravitational wave observatory. The payload of LISA Pathfinder is the so-called LISA Technology Package, which is designed to measure relative accelerations between two test masses in nominal free fall. Its disturbances are monitored and dealt by the diagnostics subsystem. This subsystem consists of several modules, and one of these is the magnetic diagnostics system, which includes a set of four tri-axial fluxgate magnetometers, intended to measure with high precision the magnetic field at the positions of the test masses. However, since the magnetometers are located far from the positions of the test masses, the magnetic field at their positions must be interpolated. It has been recently shown that because there are not enough magnetic channels, classical interpolation methods fail to derive reliable measurements at the positions of the test masses, while neural network interpolation can provide the required measurements at the desired accuracy. In this paper we expand these studies and we assess the reliability and robustness of the neural network interpolation scheme for variations of the locations and possible offsets of the magnetometers, as well as for changes in environmental conditions. We find that neural networks are robust enough to derive accurate measurements of the magnetic field at the positions of the test masses in most circumstances. |
gr-qc/0404023 | Ian Hinder | Sascha Husa, Ian Hinder and Christiane Lechner | Kranc: a Mathematica application to generate numerical codes for
tensorial evolution equations | 24 pages, 1 figure. Corresponds to journal version | Comput.Phys.Commun.174:983-1004,2006 | 10.1016/j.cpc.2006.02.002 | AEI-2004-031 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a suite of Mathematica-based computer-algebra packages, termed
"Kranc", which comprise a toolbox to convert (tensorial) systems of partial
differential evolution equations to parallelized C or Fortran code. Kranc can
be used as a "rapid prototyping" system for physicists or mathematicians
handling very complicated systems of partial differential equations, but
through integration into the Cactus computational toolkit we can also produce
efficient parallelized production codes. Our work is motivated by the field of
numerical relativity, where Kranc is used as a research tool by the authors. In
this paper we describe the design and implementation of both the Mathematica
packages and the resulting code, we discuss some example applications, and
provide results on the performance of an example numerical code for the
Einstein equations.
| [
{
"created": "Tue, 6 Apr 2004 14:12:01 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Aug 2010 14:17:23 GMT",
"version": "v2"
}
] | 2014-11-17 | [
[
"Husa",
"Sascha",
""
],
[
"Hinder",
"Ian",
""
],
[
"Lechner",
"Christiane",
""
]
] | We present a suite of Mathematica-based computer-algebra packages, termed "Kranc", which comprise a toolbox to convert (tensorial) systems of partial differential evolution equations to parallelized C or Fortran code. Kranc can be used as a "rapid prototyping" system for physicists or mathematicians handling very complicated systems of partial differential equations, but through integration into the Cactus computational toolkit we can also produce efficient parallelized production codes. Our work is motivated by the field of numerical relativity, where Kranc is used as a research tool by the authors. In this paper we describe the design and implementation of both the Mathematica packages and the resulting code, we discuss some example applications, and provide results on the performance of an example numerical code for the Einstein equations. |
1906.05155 | Emanuele Berti | Ryan McManus, Emanuele Berti, Caio F. B. Macedo, Masashi Kimura,
Andrea Maselli, Vitor Cardoso | Parametrized black hole quasinormal ringdown. II. Coupled equations and
quadratic corrections for nonrotating black holes | 14 pages, 5 figures, 3 tables. Tabulated coefficients for generic QNM
calculations are available online (see the conclusions for a computational
recipe). v2: fixed minor typos to match version in press in PRD. v3: added a
few references, matches version published in PRD | Phys. Rev. D 100, 044061 (2019) | 10.1103/PhysRevD.100.044061 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Linear perturbations of spherically symmetric spacetimes in general
relativity are described by radial wave equations, with potentials that depend
on the spin of the perturbing field. In previous work we studied the
quasinormal mode spectrum of spacetimes for which the radial potentials are
slightly modified from their general relativistic form, writing generic small
modifications as a power-series expansion in the radial coordinate. We assumed
that the perturbations in the quasinormal frequencies are linear in some
perturbative parameter, and that there is no coupling between the perturbation
equations. In general, matter fields and modifications to the gravitational
field equations lead to coupled wave equations. Here we extend our previous
analysis in two important ways: we study second-order corrections in the
perturbative parameter, and we address the more complex (and realistic) case of
coupled wave equations. We highlight the special nature of coupling-induced
corrections when two of the wave equations have degenerate spectra, and we
provide a ready-to-use recipe to compute quasinormal modes. We illustrate the
power of our parametrization by applying it to various examples, including
dynamical Chern-Simons gravity, Horndeski gravity and an effective field
theory-inspired model.
| [
{
"created": "Wed, 12 Jun 2019 14:14:07 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Aug 2019 12:26:45 GMT",
"version": "v2"
},
{
"created": "Fri, 30 Aug 2019 15:00:23 GMT",
"version": "v3"
}
] | 2019-09-04 | [
[
"McManus",
"Ryan",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Macedo",
"Caio F. B.",
""
],
[
"Kimura",
"Masashi",
""
],
[
"Maselli",
"Andrea",
""
],
[
"Cardoso",
"Vitor",
""
]
] | Linear perturbations of spherically symmetric spacetimes in general relativity are described by radial wave equations, with potentials that depend on the spin of the perturbing field. In previous work we studied the quasinormal mode spectrum of spacetimes for which the radial potentials are slightly modified from their general relativistic form, writing generic small modifications as a power-series expansion in the radial coordinate. We assumed that the perturbations in the quasinormal frequencies are linear in some perturbative parameter, and that there is no coupling between the perturbation equations. In general, matter fields and modifications to the gravitational field equations lead to coupled wave equations. Here we extend our previous analysis in two important ways: we study second-order corrections in the perturbative parameter, and we address the more complex (and realistic) case of coupled wave equations. We highlight the special nature of coupling-induced corrections when two of the wave equations have degenerate spectra, and we provide a ready-to-use recipe to compute quasinormal modes. We illustrate the power of our parametrization by applying it to various examples, including dynamical Chern-Simons gravity, Horndeski gravity and an effective field theory-inspired model. |
1009.2941 | H Mohseni Sadjadi | H. Mohseni Sadjadi | Cosmological entropy and generalized second law of thermodynamics in
$F(R,G)$ theory of gravity | 10 pages, minor changes, typos corrected, accepted for publication in
Europhysics Letters | Europhys.Lett.92:50014,2010 | 10.1209/0295-5075/92/50014 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a spatially flat Friedmann-Lemaitre-Robertson-Walker space time
and investigate the second law and the generalized second law of thermodynamics
for apparent horizon in generalized modified Gauss Bonnet theory of gravity
(whose action contains a general function of Gauss Bonnet invariant and the
Ricci scalar: $F(R,G)$). By assuming that the apparent horizon is in thermal
equilibrium with the matter inside it, conditions which must be satisfied by
$F(R,G)$ are derived and elucidated through two examples: a quasi-de Sitter
space-time and a universe with power law expansion.
| [
{
"created": "Wed, 15 Sep 2010 14:37:04 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Dec 2010 13:15:05 GMT",
"version": "v2"
}
] | 2011-01-17 | [
[
"Sadjadi",
"H. Mohseni",
""
]
] | We consider a spatially flat Friedmann-Lemaitre-Robertson-Walker space time and investigate the second law and the generalized second law of thermodynamics for apparent horizon in generalized modified Gauss Bonnet theory of gravity (whose action contains a general function of Gauss Bonnet invariant and the Ricci scalar: $F(R,G)$). By assuming that the apparent horizon is in thermal equilibrium with the matter inside it, conditions which must be satisfied by $F(R,G)$ are derived and elucidated through two examples: a quasi-de Sitter space-time and a universe with power law expansion. |
1111.7314 | Collin Capano | the LIGO Scientific Collaboration and the Virgo Collaboration: J.
Abadie, B. P. Abbott, R. Abbott, T. D. Abbott, M. Abernathy, T. Accadia, F.
Acernese, C. Adams, R. Adhikari, C. Affeldt, M. Agathos, P. Ajith, B. Allen,
G. S. Allen, E. Amador Ceron, D. Amariutei, R. S. Amin, S. B. Anderson, W. G.
Anderson, K. Arai, M. A. Arain, M. C. Araya, S. M. Aston, P. Astone, D.
Atkinson, P. Aufmuth, C. Aulbert, B. E. Aylott, S. Babak, P. Baker, G.
Ballardin, S. Ballmer, D. Barker, F. Barone, B. Barr, P. Barriga, L.
Barsotti, M. Barsuglia, M. A. Barton, I. Bartos, R. Bassiri, M. Bastarrika,
A. Basti, J. Batch, J. Bauchrowitz, Th. S. Bauer, M. Bebronne, B. Behnke,
M.G. Beker, A. S. Bell, A. Belletoile, I. Belopolski, M. Benacquista, J. M.
Berliner, A. Bertolini, J. Betzwieser, N. Beveridge, P. T. Beyersdorf, I. A.
Bilenko, G. Billingsley, J. Birch, R. Biswas, M. Bitossi, M. A. Bizouard, E.
Black, J. K. Blackburn, L. Blackburn, D. Blair, B. Bland, M. Blom, O. Bock,
T. P. Bodiya, C. Bogan, R. Bondarescu, F. Bondu, L. Bonelli, R. Bonnand, R.
Bork, M. Born, V. Boschi, S. Bose, L. Bosi, B. Bouhou, S. Braccini, C.
Bradaschia, P. R. Brady, V. B. Braginsky, M. Branchesi, J. E. Brau, J.
Breyer, T. Briant, D. O. Bridges, A. Brillet, M. Brinkmann, V. Brisson, M.
Britzger, A. F. Brooks, D. A. Brown, A. Brummit, T. Bulik, H. J. Bulten, A.
Buonanno, J. Burguet--Castell, O. Burmeister, D. Buskulic, C. Buy, R. L.
Byer, L. Cadonati, G. Cagnoli, E. Calloni, J. B. Camp, P. Campsie, J.
Cannizzo, K. Cannon, B. Canuel, J. Cao, C. D. Capano, F. Carbognani, S.
Caride, S. Caudill, M. Cavagli\`a, F. Cavalier, R. Cavalieri, G. Cella, C.
Cepeda, E. Cesarini, O. Chaibi, T. Chalermsongsak, E. Chalkley, P. Charlton,
E. Chassande-Mottin, S. Chelkowski, Y. Chen, A. Chincarini, A. Chiummo, H.
Cho, N. Christensen, S. S. Y. Chua, C. T. Y. Chung, S. Chung, G. Ciani, F.
Clara, D. E. Clark, J. Clark, J. H. Clayton, F. Cleva, E. Coccia, P.-F.
Cohadon, C. N. Colacino, J. Colas, A. Colla, M. Colombini, A. Conte, R.
Conte, D. Cook, T. R. Corbitt, M. Cordier, N. Cornish, A. Corsi, C. A. Costa,
M. Coughlin, J.-P. Coulon, P. Couvares, D. M. Coward, D. C. Coyne, J. D. E.
Creighton, T. D. Creighton, A. M. Cruise, A. Cumming, L. Cunningham, E.
Cuoco, R. M. Cutler, K. Dahl, S. L. Danilishin, R. Dannenberg, S. D'Antonio,
K. Danzmann, V. Dattilo, B. Daudert, H. Daveloza, M. Davier, G. Davies, E. J.
Daw, R. Day, T. Dayanga, R. De Rosa, D. DeBra, G. Debreczeni, J. Degallaix,
W. Del Pozzo, M. del Prete, T. Dent, V. Dergachev, R. DeRosa, R. DeSalvo, S.
Dhurandhar, L. Di Fiore, A. Di Lieto, I. Di Palma, M. Di Paolo Emilio, A. Di
Virgilio, M. D\'iaz, A. Dietz, J. DiGuglielmo, F. Donovan, K. L. Dooley, S.
Dorsher, M. Drago, R. W. P. Drever, J. C. Driggers, Z. Du, J.-C. Dumas, S.
Dwyer, T. Eberle, M. Edgar, M. Edwards, A. Effler, P. Ehrens, G. Endr\"oczi,
R. Engel, T. Etzel, K. Evans, M. Evans, T. Evans, M. Factourovich, V. Fafone,
S. Fairhurst, Y. Fan, B. F. Farr, W. Farr, D. Fazi, H. Fehrmann, D. Feldbaum,
I. Ferrante, F. Fidecaro, L. S. Finn, I. Fiori, R. P. Fisher, R. Flaminio, M.
Flanigan, S. Foley, E. Forsi, L. A. Forte, N. Fotopoulos, J.-D. Fournier, J.
Franc, S. Frasca, F. Frasconi, M. Frede, M. Frei, Z. Frei, A. Freise, R.
Frey, T. T. Fricke, D. Friedrich, P. Fritschel, V. V. Frolov, P. J. Fulda, M.
Fyffe, M. Galimberti, L. Gammaitoni, M. R. Ganija, J. Garcia, J. A. Garofoli,
F. Garufi, M. E. G\'asp\'ar, G. Gemme, R. Geng, E. Genin, A. Gennai, L. \'A.
Gergely, S. Ghosh, J. A. Giaime, S. Giampanis, K. D. Giardina, A. Giazotto,
C. Gill, E. Goetz, L. M. Goggin, G. Gonz\'alez, M. L. Gorodetsky, S.
Go{\ss}ler, R. Gouaty, C. Graef, M. Granata, A. Grant, S. Gras, C. Gray, N.
Gray, R. J. S. Greenhalgh, A. M. Gretarsson, C. Greverie, R. Grosso, H.
Grote, S. Grunewald, G. M. Guidi, C. Guido, R. Gupta, E. K. Gustafson, R.
Gustafson, T. Ha, B. Hage, J. M. Hallam, D. Hammer, G. Hammond, J. Hanks, C.
Hanna, J. Hanson, A. Hardt, J. Harms, G. M. Harry, I. W. Harry, E. D.
Harstad, M. T. Hartman, K. Haughian, K. Hayama, J.-F. Hayau, J. Heefner, A.
Heidmann, M. C. Heintze, H. Heitmann, P. Hello, M. A. Hendry, I. S. Heng, A.
W. Heptonstall, V. Herrera, M. Hewitson, S. Hild, D. Hoak, K. A. Hodge, K.
Holt, T. Hong, S. Hooper, D. J. Hosken, J. Hough, E. J. Howell, B. Hughey, S.
Husa, S. H. Huttner, T. Huynh-Dinh, D. R. Ingram, R. Inta, T. Isogai, A.
Ivanov, K. Izumi, M. Jacobson, H. Jang, P. Jaranowski, W. W. Johnson, D. I.
Jones, G. Jones, R. Jones, L. Ju, P. Kalmus, V. Kalogera, I. Kamaretsos, S.
Kandhasamy, G. Kang, J. B. Kanner, E. Katsavounidis, W. Katzman, H. Kaufer,
K. Kawabe, S. Kawamura, F. Kawazoe, W. Kells, D. G. Keppel, Z. Keresztes, A.
Khalaidovski, F. Y. Khalili, E. A. Khazanov, B. Kim, C. Kim, D. Kim, H. Kim,
K. Kim, N. Kim, Y. -M. Kim, P. J. King, M. Kinsey, D. L. Kinzel, J. S.
Kissel, S. Klimenko, K. Kokeyama, V. Kondrashov, R. Kopparapu, S. Koranda, W.
Z. Korth, I. Kowalska, D. Kozak, V. Kringel, S. Krishnamurthy, B. Krishnan,
A. Kr\'olak, G. Kuehn, R. Kumar, P. Kwee, P. K. Lam, M. Landry, M. Lang, B.
Lantz, N. Lastzka, C. Lawrie, A. Lazzarini, P. Leaci, C. H. Lee, H. M. Lee,
N. Leindecker, J. R. Leong, I. Leonor, N. Leroy, N. Letendre, J. Li, T. G. F.
Li, N. Liguori, P. E. Lindquist, N. A. Lockerbie, D. Lodhia, M. Lorenzini, V.
Loriette, M. Lormand, G. Losurdo, J. Luan, M. Lubinski, H. L\"uck, A. P.
Lundgren, E. Macdonald, B. Machenschalk, M. MacInnis, D. M. Macleod, M.
Mageswaran, K. Mailand, E. Majorana, I. Maksimovic, N. Man, I. Mandel, V.
Mandic, M. Mantovani, A. Marandi, F. Marchesoni, F. Marion, S. M\'arka, Z.
M\'arka, A. Markosyan, E. Maros, J. Marque, F. Martelli, I. W. Martin, R. M.
Martin, J. N. Marx, K. Mason, A. Masserot, F. Matichard, L. Matone, R. A.
Matzner, N. Mavalvala, G. Mazzolo, R. McCarthy, D. E. McClelland, S. C.
McGuire, G. McIntyre, J. McIver, D. J. A. McKechan, G. D. Meadors, M. Mehmet,
T. Meier, A. Melatos, A. C. Melissinos, G. Mendell, D. Menendez, R. A.
Mercer, S. Meshkov, C. Messenger, M. S. Meyer, H. Miao, C. Michel, L. Milano,
J. Miller, Y. Minenkov, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, O.
Miyakawa, B. Moe, P. Moesta, M. Mohan, S. D. Mohanty, S. R. P. Mohapatra, D.
Moraru, G. Moreno, N. Morgado, A. Morgia, T. Mori, S. Mosca, K. Mossavi, B.
Mours, C. M. Mow--Lowry, C. L. Mueller, G. Mueller, S. Mukherjee, A.
Mullavey, H. M\"uller-Ebhardt, J. Munch, D. Murphy, P. G. Murray, A. Mytidis,
T. Nash, L. Naticchioni, R. Nawrodt, V. Necula, J. Nelson, G. Newton, A.
Nishizawa, F. Nocera, D. Nolting, L. Nuttall, E. Ochsner, J. O'Dell, E.
Oelker, G. H. Ogin, J. J. Oh, S. H. Oh, R. G. Oldenburg, B. O'Reilly, R.
O'Shaughnessy, C. Osthelder, C. D. Ott, D. J. Ottaway, R. S. Ottens, H.
Overmier, B. J. Owen, A. Page, G. Pagliaroli, L. Palladino, C. Palomba, Y.
Pan, C. Pankow, F. Paoletti, M. A. Papa, M. Parisi, A. Pasqualetti, R.
Passaquieti, D. Passuello, P. Patel, M. Pedraza, P. Peiris, L. Pekowsky, S.
Penn, C. Peralta, A. Perreca, G. Persichetti, M. Phelps, M. Pickenpack, F.
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V. Plissi, R. Poggiani, J. P\"old, F. Postiglione, M. Prato, V. Predoi, L. R.
Price, M. Prijatelj, M. Principe, S. Privitera, R. Prix, G. A. Prodi, L.
Prokhorov, O. Puncken, M. Punturo, P. Puppo, V. Quetschke, F. J. Raab, D. S.
Rabeling, I. R\'acz, H. Radkins, P. Raffai, M. Rakhmanov, C. R. Ramet, B.
Rankins, P. Rapagnani, V. Raymond, V. Re, K. Redwine, C. M. Reed, T. Reed, T.
Regimbau, S. Reid, D. H. Reitze, F. Ricci, R. Riesen, K. Riles, N. A.
Robertson, F. Robinet, C. Robinson, E. L. Robinson, A. Rocchi, S. Roddy, C.
Rodriguez, M. Rodruck, L. Rolland, J. Rollins, J. D. Romano, R. Romano, J. H.
Romie, D. Rosi\'nska, C. R\"over, S. Rowan, A. R\"udiger, P. Ruggi, K. Ryan,
H. Ryll, P. Sainathan, M. Sakosky, F. Salemi, A. Samblowski, L. Sammut, L.
Sancho de la Jordana, V. Sandberg, S. Sankar, V. Sannibale, L. Santamar\'ia,
I. Santiago-Prieto, G. Santostasi, B. Sassolas, B. S. Sathyaprakash, S. Sato,
P. R. Saulson, R. L. Savage, R. Schilling, S. Schlamminger, R. Schnabel, R.
M. S. Schofield, B. Schulz, B. F. Schutz, P. Schwinberg, J. Scott, S. M.
Scott, A. C. Searle, F. Seifert, D. Sellers, A. S. Sengupta, D. Sentenac, A.
Sergeev, D. A. Shaddock, M. Shaltev, B. Shapiro, P. Shawhan, D. H. Shoemaker,
A. Sibley, X. Siemens, D. Sigg, A. Singer, L. Singer, A. M. Sintes, G.
Skelton, B. J. J. Slagmolen, J. Slutsky, J. R. Smith, M. R. Smith, N. D.
Smith, R. J. E. Smith, K. Somiya, B. Sorazu, J. Soto, F. C. Speirits, L.
Sperandio, M. Stefszky, A. J. Stein, E. Steinert, J. Steinlechner, S.
Steinlechner, S. Steplewski, A. Stochino, R. Stone, K. A. Strain, S. Strigin,
A. S. Stroeer, R. Sturani, A. L. Stuver, T. Z. Summerscales, M. Sung, S.
Susmithan, P. J. Sutton, B. Swinkels, M. Tacca, L. Taffarello, D. Talukder,
D. B. Tanner, S. P. Tarabrin, J. R. Taylor, R. Taylor, P. Thomas, K. A.
Thorne, K. S. Thorne, E. Thrane, A. Th\"uring, C. Titsler, K. V. Tokmakov, A.
Toncelli, M. Tonelli, O. Torre, C. Torres, C. I. Torrie, E. Tournefier, F.
Travasso, G. Traylor, M. Trias, K. Tseng, E. Tucker, D. Ugolini, K. Urbanek,
H. Vahlbruch, G. Vajente, M. Vallisneri, J. F. J. van den Brand, C. Van Den
Broeck, S. van der Putten, A. A. van Veggel, S. Vass, M. Vasuth, R. Vaulin,
M. Vavoulidis, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, C. Veltkamp,
D. Verkindt, F. Vetrano, A. Vicer\'e, A. E. Villar, J.-Y. Vinet, S. Vitale,
S. Vitale, H. Vocca, C. Vorvick, S. P. Vyatchanin, A. Wade, S. J. Waldman, L.
Wallace, Y. Wan, X. Wang, Z. Wang, A. Wanner, R. L. Ward, M. Was, P. Wei, M.
Weinert, A. J. Weinstein, R. Weiss, L. Wen, S. Wen, P. Wessels, M. West, T.
Westphal, K. Wette, J. T. Whelan, S. E. Whitcomb, D. White, B. F. Whiting, C.
Wilkinson, P. A. Willems, H. R. Williams, L. Williams, B. Willke, L.
Winkelmann, W. Winkler, C. C. Wipf, A. G. Wiseman, H. Wittel, G. Woan, R.
Wooley, J. Worden, J. Yablon, I. Yakushin, H. Yamamoto, K. Yamamoto, H. Yang,
D. Yeaton-Massey, S. Yoshida, P. Yu, M. Yvert, A. Zadro\'zny, M. Zanolin,
J.-P. Zendri, F. Zhang, L. Zhang, W. Zhang, Z. Zhang, C. Zhao, N. Zotov, M.
E. Zucker, J. Zweizig | Search for Gravitational Waves from Low Mass Compact Binary Coalescence
in LIGO's Sixth Science Run and Virgo's Science Runs 2 and 3 | 11 pages, 5 figures. For a repository of data used in the
publication, go to:
<https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=39633>. Also see the
announcement for this paper on ligo.org at:
<http://www.ligo.org/science/Publication-S6CBCLowMass/index.php> | Phys. Rev. D 85, 082002 (2012) | 10.1103/PhysRevD.85.082002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We report on a search for gravitational waves from coalescing compact
binaries using LIGO and Virgo observations between July 7, 2009 and October 20,
2010. We searched for signals from binaries with total mass between 2 and 25
solar masses; this includes binary neutron stars, binary black holes, and
binaries consisting of a black hole and neutron star. The detectors were
sensitive to systems up to 40 Mpc distant for binary neutron stars, and further
for higher mass systems. No gravitational-wave signals were detected. We report
upper limits on the rate of compact binary coalescence as a function of total
mass, including the results from previous LIGO and Virgo observations. The
cumulative 90%-confidence rate upper limits of the binary coalescence of binary
neutron star, neutron star- black hole and binary black hole systems are 1.3 x
10^{-4}, 3.1 x 10^{-5} and 6.4 x 10^{-6} Mpc^{-3}yr^{-1}, respectively. These
upper limits are up to a factor 1.4 lower than previously derived limits. We
also report on results from a blind injection challenge.
| [
{
"created": "Wed, 30 Nov 2011 20:49:41 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Dec 2011 19:42:40 GMT",
"version": "v2"
},
{
"created": "Fri, 16 Dec 2011 20:18:59 GMT",
"version": "v3"
},
{
"created": "Wed, 18 Jan 2012 17:41:51 GMT",
"version": "v4"
}
] | 2012-08-27 | [
[
"the LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"Abadie",
"J.",
""
],
[
"Abbott",
"B. P.",
""
],
[
"Abbott",
"R.",
""
],
[
"Abbott",
"T. D.",
""
],
[
"Abernathy",
"M.",
... | We report on a search for gravitational waves from coalescing compact binaries using LIGO and Virgo observations between July 7, 2009 and October 20, 2010. We searched for signals from binaries with total mass between 2 and 25 solar masses; this includes binary neutron stars, binary black holes, and binaries consisting of a black hole and neutron star. The detectors were sensitive to systems up to 40 Mpc distant for binary neutron stars, and further for higher mass systems. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass, including the results from previous LIGO and Virgo observations. The cumulative 90%-confidence rate upper limits of the binary coalescence of binary neutron star, neutron star- black hole and binary black hole systems are 1.3 x 10^{-4}, 3.1 x 10^{-5} and 6.4 x 10^{-6} Mpc^{-3}yr^{-1}, respectively. These upper limits are up to a factor 1.4 lower than previously derived limits. We also report on results from a blind injection challenge. |
1401.7550 | Sergey Yu. Vernov | Ekaterina O. Pozdeeva, Sergey Yu. Vernov | Stable Exact Cosmological Solutions in Induced Gravity Models | 19 pages, 2 figures, v2: one figure and references added | AIP Conf. Proc. 1606 (2014) 48-58 | 10.1063/1.4891115 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study dynamics of induced gravity cosmological models with sixth degree
potential, that have found using the superpotential method. The important
property of these models are existence of exact cosmological solutions that
tend to fixed points. The stability of these cosmological solutions have been
obtained. In particular, we find conditions under which solutions with a
non-monotonic Hubble parameter that tend to a fixed point are attractors.
| [
{
"created": "Tue, 28 Jan 2014 19:59:35 GMT",
"version": "v1"
},
{
"created": "Sat, 12 Apr 2014 08:00:18 GMT",
"version": "v2"
}
] | 2014-07-29 | [
[
"Pozdeeva",
"Ekaterina O.",
""
],
[
"Vernov",
"Sergey Yu.",
""
]
] | We study dynamics of induced gravity cosmological models with sixth degree potential, that have found using the superpotential method. The important property of these models are existence of exact cosmological solutions that tend to fixed points. The stability of these cosmological solutions have been obtained. In particular, we find conditions under which solutions with a non-monotonic Hubble parameter that tend to a fixed point are attractors. |
1505.08058 | Edward Porter | Edward K. Porter | The effect of different eLISA-like configurations on massive black hole
parameter estimation | 9 pages, 5 figures | Phys. Rev. D 92, 064001 (2015) | 10.1103/PhysRevD.92.064001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | As the theme for the future L3 Cosmic Vision mission, ESA has recently chosen
the `Gravitational Wave Universe'. Within this call, a mission concept called
eLISA has been proposed. This observatory has a current initial configuration
consisting of 4 laser links between the three satellites, which are separated
by a distance of one million kilometers, constructing a single channel
Michelson interferometer. However, the final configuration for the observatory
will not be fixed until the end of this decade. With this in mind, we
investigate the effect of different eLISA-like configurations on massive black
hole detections. This work compares the results of a Bayesian inference study
of 120 massive black hole binaries out to a redshift of $z\sim13$ for a $10^6$m
arm-length eLISA with four and six links, as well as a $2\times10^6$m
arm-length observatory with four links. We demonstrate that the original eLISA
configuration should allow us to recover the luminosity distance of the source
with an error of less than 10% out to a redshift of $z\sim4$, and a sky error
box of $\leq10^2\,deg^2$ out to $z\sim0.1$. In contrast, both alternative
configurations suggest that we should be able to conduct the same parameter
recovery with errors of less than 10% in luminosity distance out to $z\sim12$
and $\leq10^2\,deg^2$ out to $z\sim0.4$. Using the information from these
studies, we also infer that if we were able to construct a 2Gm, 6-link
detector, the above values would shift to $z\sim20$ for luminosity distance and
$z\sim0.9$ for sky error. While the final configuration will also be dependent
on both technological and financial considerations, our study suggests that
increasing the size of a two arm detector is a viable alternative to the
inclusion of a third arm in a smaller detector. More importantly, this work
further suggests no clear scientific loss between either choice.
| [
{
"created": "Fri, 29 May 2015 14:26:44 GMT",
"version": "v1"
}
] | 2015-09-09 | [
[
"Porter",
"Edward K.",
""
]
] | As the theme for the future L3 Cosmic Vision mission, ESA has recently chosen the `Gravitational Wave Universe'. Within this call, a mission concept called eLISA has been proposed. This observatory has a current initial configuration consisting of 4 laser links between the three satellites, which are separated by a distance of one million kilometers, constructing a single channel Michelson interferometer. However, the final configuration for the observatory will not be fixed until the end of this decade. With this in mind, we investigate the effect of different eLISA-like configurations on massive black hole detections. This work compares the results of a Bayesian inference study of 120 massive black hole binaries out to a redshift of $z\sim13$ for a $10^6$m arm-length eLISA with four and six links, as well as a $2\times10^6$m arm-length observatory with four links. We demonstrate that the original eLISA configuration should allow us to recover the luminosity distance of the source with an error of less than 10% out to a redshift of $z\sim4$, and a sky error box of $\leq10^2\,deg^2$ out to $z\sim0.1$. In contrast, both alternative configurations suggest that we should be able to conduct the same parameter recovery with errors of less than 10% in luminosity distance out to $z\sim12$ and $\leq10^2\,deg^2$ out to $z\sim0.4$. Using the information from these studies, we also infer that if we were able to construct a 2Gm, 6-link detector, the above values would shift to $z\sim20$ for luminosity distance and $z\sim0.9$ for sky error. While the final configuration will also be dependent on both technological and financial considerations, our study suggests that increasing the size of a two arm detector is a viable alternative to the inclusion of a third arm in a smaller detector. More importantly, this work further suggests no clear scientific loss between either choice. |
1111.1472 | Edward Anderson | Edward Anderson | The Problem of Time and Quantum Cosmology in the Relational Particle
Mechanics Arena | This v3 is a v substantial upgrade: previous v's did not yet announce
a local solution, we're up by 77 pages (to 386) & by 35 figs (to 93). It is
now a quartet of Theses, the Problem of Time one of v1 splitting into cl and
qm parts. I Cl RPM's. II Cl Problem of Time. III QM RPM's. IV QM Problem of
Time. Contains over 100 interesting & foundational suggestions for future
projects | null | null | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article contains a local solution to the notorious Problem of Time in
Quantum Gravity at the conceptual level and which is actually realizable for
the relational triangle. The Problem of Time is that `time' in GR and `time' in
ordinary quantum theory are mutually incompatible notions, which is problematic
in trying to put these two theories together to form a theory of Quantum
Gravity. Four frontiers to this resolution in full GR are identified, alongside
three further directions not yet conquered even for the relational triangle.
This article is also the definitive review on relational particle models
originally due to Barbour (2003: dynamics of pure shape) and Barbour and
Bertotti (1982: dynamics of shape and scale). These are exhibited as useful toy
models of background independence, which I argue to be the `other half' of GR
to relativistic gravitation, as well as the originator of the Problem of Time
itself. Barbour's work and my localized extension of it are shown to be the
classical precursor of the background independence that then manifests itself
at the quantum level as the full-blown Problem of Time. In fact 7/8ths of the
Isham--Kuchar Problem of Time facets are already present in classical GR; even
classical mechanics in relational particle mechanics formulation exhibits
5/8ths of these! In addition to Isham, Kuchar and Barbour, the other principal
authors whose works are drawn upon in building this Problem of Time approach
are Kendall (relational models only: pure-shape configuration spaces), Dirac,
Teitelboim and Halliwell (Problem of Time resolving components). The
recommended scheme is a combination of the Machian semiclassical approach,
histories theory and records theory.
| [
{
"created": "Mon, 7 Nov 2011 02:22:30 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Mar 2012 17:18:32 GMT",
"version": "v2"
},
{
"created": "Tue, 12 Feb 2013 21:49:15 GMT",
"version": "v3"
}
] | 2015-03-19 | [
[
"Anderson",
"Edward",
""
]
] | This article contains a local solution to the notorious Problem of Time in Quantum Gravity at the conceptual level and which is actually realizable for the relational triangle. The Problem of Time is that `time' in GR and `time' in ordinary quantum theory are mutually incompatible notions, which is problematic in trying to put these two theories together to form a theory of Quantum Gravity. Four frontiers to this resolution in full GR are identified, alongside three further directions not yet conquered even for the relational triangle. This article is also the definitive review on relational particle models originally due to Barbour (2003: dynamics of pure shape) and Barbour and Bertotti (1982: dynamics of shape and scale). These are exhibited as useful toy models of background independence, which I argue to be the `other half' of GR to relativistic gravitation, as well as the originator of the Problem of Time itself. Barbour's work and my localized extension of it are shown to be the classical precursor of the background independence that then manifests itself at the quantum level as the full-blown Problem of Time. In fact 7/8ths of the Isham--Kuchar Problem of Time facets are already present in classical GR; even classical mechanics in relational particle mechanics formulation exhibits 5/8ths of these! In addition to Isham, Kuchar and Barbour, the other principal authors whose works are drawn upon in building this Problem of Time approach are Kendall (relational models only: pure-shape configuration spaces), Dirac, Teitelboim and Halliwell (Problem of Time resolving components). The recommended scheme is a combination of the Machian semiclassical approach, histories theory and records theory. |
gr-qc/9809005 | Jorma Louko | Claus Kiefer and Jorma Louko | Hamiltonian evolution and quantization for extremal black holes | 16 pages, LaTeX using REVTeX v3.1. (v2: Reference added.) | Annalen Phys.8:67-81,1999 | null | Freiburg THEP-98/18 | gr-qc | null | We present and contrast two distinct ways of including extremal black holes
in a Lorentzian Hamiltonian quantization of spherically symmetric
Einstein-Maxwell theory. First, we formulate the classical Hamiltonian dynamics
with boundary conditions appropriate for extremal black holes only. The
Hamiltonian contains no surface term at the internal infinity, for reasons
related to the vanishing of the extremal hole surface gravity, and quantization
yields a vanishing black hole entropy. Second, we give a Hamiltonian
quantization that incorporates extremal black holes as a limiting case of
nonextremal ones, and examine the classical limit in terms of wave packets. The
spreading of the packets, even the ones centered about extremal black holes, is
consistent with continuity of the entropy in the extremal limit, and thus with
the Bekenstein-Hawking entropy even for the extremal holes. The discussion
takes place throughout within Lorentz-signature spacetimes.
| [
{
"created": "Tue, 1 Sep 1998 15:20:41 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Sep 1998 15:33:52 GMT",
"version": "v2"
}
] | 2014-10-01 | [
[
"Kiefer",
"Claus",
""
],
[
"Louko",
"Jorma",
""
]
] | We present and contrast two distinct ways of including extremal black holes in a Lorentzian Hamiltonian quantization of spherically symmetric Einstein-Maxwell theory. First, we formulate the classical Hamiltonian dynamics with boundary conditions appropriate for extremal black holes only. The Hamiltonian contains no surface term at the internal infinity, for reasons related to the vanishing of the extremal hole surface gravity, and quantization yields a vanishing black hole entropy. Second, we give a Hamiltonian quantization that incorporates extremal black holes as a limiting case of nonextremal ones, and examine the classical limit in terms of wave packets. The spreading of the packets, even the ones centered about extremal black holes, is consistent with continuity of the entropy in the extremal limit, and thus with the Bekenstein-Hawking entropy even for the extremal holes. The discussion takes place throughout within Lorentz-signature spacetimes. |
gr-qc/0312110 | Parampreet Singh | Parampreet Singh, Alexey Toporensky | Big Crunch Avoidance in k = 1 Semi-Classical Loop Quantum Cosmology | Minor changes, To appear in Physical Review D | Phys.Rev. D69 (2004) 104008 | 10.1103/PhysRevD.69.104008 | null | gr-qc astro-ph hep-th | null | It is well known that a closed universe with a minimally coupled massive
scalar field always collapses to a singularity unless the initial conditions
are extremely fine tuned. We show that the corrections to the equations of
motion for the massive scalar field, given by loop quantum gravity in high
curvature regime, always lead to a bounce independently of the initial
conditions. In contrast to the previous works in loop quantum cosmology, we
note that the singularity can be avoided even at the semi-classical level of
effective dynamical equations with non-perturbative quantum gravity
modifications, without using a discrete quantum evolution.
| [
{
"created": "Thu, 25 Dec 2003 09:50:49 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Jan 2004 12:11:49 GMT",
"version": "v2"
},
{
"created": "Thu, 26 Feb 2004 04:51:55 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Singh",
"Parampreet",
""
],
[
"Toporensky",
"Alexey",
""
]
] | It is well known that a closed universe with a minimally coupled massive scalar field always collapses to a singularity unless the initial conditions are extremely fine tuned. We show that the corrections to the equations of motion for the massive scalar field, given by loop quantum gravity in high curvature regime, always lead to a bounce independently of the initial conditions. In contrast to the previous works in loop quantum cosmology, we note that the singularity can be avoided even at the semi-classical level of effective dynamical equations with non-perturbative quantum gravity modifications, without using a discrete quantum evolution. |
1806.09500 | Che-Yu Chen | Che-Yu Chen, Pisin Chen | Quasi-normal modes of massless scalar fields for charged black holes in
the Palatini-type gravity | 13 pages, 6 figures, revised version, accepted for publication in PRD | Phys. Rev. D 98, 044042 (2018) | 10.1103/PhysRevD.98.044042 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The scrutiny of black hole perturbations and its application to testing
gravity theories have been a very crucial frontier in modern physics. In this
paper we study the quasi-normal modes (QNM) of massless scalar perturbations
for various charged black holes in the Palatini-type theories of gravity.
Specifically, we consider the Palatini $f(R)$ theory coupled with Born-Infeld
nonlinear electrodynamics and the Eddington-inspired-Born-Infeld gravity (EiBI)
coupled with Maxwell electromagnetic fields. Special attention is paid to
Einstein-Born-Infeld black holes, EiBI charged black holes and Born-Infeld
charged black holes within $R\pm R^2$ gravity. These charged black holes are
shown to be stable and their quasi-normal frequencies, including the
frequencies in the eikonal limit, are calculated by using the WKB method up to
the 6th order. We compare the results with the Reissner-Nordstr\"om charged
black hole and prove that both the changes in the gravity sector and the matter
sector of the action alter the QNM spectra.
| [
{
"created": "Mon, 25 Jun 2018 14:48:12 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Aug 2018 03:13:19 GMT",
"version": "v2"
}
] | 2018-09-03 | [
[
"Chen",
"Che-Yu",
""
],
[
"Chen",
"Pisin",
""
]
] | The scrutiny of black hole perturbations and its application to testing gravity theories have been a very crucial frontier in modern physics. In this paper we study the quasi-normal modes (QNM) of massless scalar perturbations for various charged black holes in the Palatini-type theories of gravity. Specifically, we consider the Palatini $f(R)$ theory coupled with Born-Infeld nonlinear electrodynamics and the Eddington-inspired-Born-Infeld gravity (EiBI) coupled with Maxwell electromagnetic fields. Special attention is paid to Einstein-Born-Infeld black holes, EiBI charged black holes and Born-Infeld charged black holes within $R\pm R^2$ gravity. These charged black holes are shown to be stable and their quasi-normal frequencies, including the frequencies in the eikonal limit, are calculated by using the WKB method up to the 6th order. We compare the results with the Reissner-Nordstr\"om charged black hole and prove that both the changes in the gravity sector and the matter sector of the action alter the QNM spectra. |
1303.0430 | Jose Ademir Sales Lima | E. L. D. Perico, J. A. S. Lima, M. Campos | Black Hole Formation with an Interacting Vacuum Energy Density:
Curvature Effects | 9 pages, 12 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gravitational collapse of a spherically symmetric massive core of a star
in which the fluid component is interacting with a growing vacuum energy
density filling a FLRW type geometry with an arbitrary curvature parameter is
investigated. The complete set of exact solutions for all values of the free
parameters are obtained and the influence of the curvature term on the
collapsing time, black hole mass and other physical quantities are also
discussed in detail. We show that for the same initial conditions the total
black hole mass depends only on the effective matter density parameter
(including the vacuum component). It is also shown that the analytical
condition to form a black hole i.e. the apparent horizon is not altered by the
contribution of the curvature terms, however, the remaining physical quantities
are quantitatively modified.
| [
{
"created": "Sat, 2 Mar 2013 21:42:55 GMT",
"version": "v1"
}
] | 2013-03-05 | [
[
"Perico",
"E. L. D.",
""
],
[
"Lima",
"J. A. S.",
""
],
[
"Campos",
"M.",
""
]
] | The gravitational collapse of a spherically symmetric massive core of a star in which the fluid component is interacting with a growing vacuum energy density filling a FLRW type geometry with an arbitrary curvature parameter is investigated. The complete set of exact solutions for all values of the free parameters are obtained and the influence of the curvature term on the collapsing time, black hole mass and other physical quantities are also discussed in detail. We show that for the same initial conditions the total black hole mass depends only on the effective matter density parameter (including the vacuum component). It is also shown that the analytical condition to form a black hole i.e. the apparent horizon is not altered by the contribution of the curvature terms, however, the remaining physical quantities are quantitatively modified. |
gr-qc/0407052 | Krzysztof A. Meissner | Krzysztof A. Meissner | Black hole entropy in Loop Quantum Gravity | LaTeX, 10 pages | Class.Quant.Grav. 21 (2004) 5245-5252 | 10.1088/0264-9381/21/22/015 | null | gr-qc | null | We calculate the black hole entropy in Loop Quantum Gravity as a function of
the horizon area and provide the exact formula for the leading and sub-leading
terms. By comparison with the Bekenstein-Hawking formula we uniquely fix the
value of the 'quantum of area' in the theory.
| [
{
"created": "Wed, 14 Jul 2004 19:36:34 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Meissner",
"Krzysztof A.",
""
]
] | We calculate the black hole entropy in Loop Quantum Gravity as a function of the horizon area and provide the exact formula for the leading and sub-leading terms. By comparison with the Bekenstein-Hawking formula we uniquely fix the value of the 'quantum of area' in the theory. |
gr-qc/0201060 | Brout | Robert Brout | The Inflaton and its Mass | LaTex file, 11 pages | null | null | null | gr-qc | null | In the context of the two fluid model of space-time fluctuations proposed to
tame the transplanckian problem encountered in black hole physics, it is
postulated that the inflaton is the fluctuation of mode density, ``the vapor
component'' of the model. The mass of the inflaton is occasioned by the
exchange of degrees of freedom between the ``vapor'' and the ``liquid'', the
planckian ``soup'' in which usual ``cisplanckian'' fields propagate. This
exchange between vacuum fluctuations is modeled after its counterpart in the
real world i.e. black hole evaporation. In order of magnitude, a very rough
semiquantitative estimate, would situate the mass somewhere between $10^{-10}$
and $10^{-5}$ planck masses, the largest uncertainty being the mass of the
planckian black hole fluctuation i.e. the entropy that one ascribes to it.
| [
{
"created": "Fri, 18 Jan 2002 16:12:38 GMT",
"version": "v1"
},
{
"created": "Sun, 20 Jan 2002 17:54:37 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Brout",
"Robert",
""
]
] | In the context of the two fluid model of space-time fluctuations proposed to tame the transplanckian problem encountered in black hole physics, it is postulated that the inflaton is the fluctuation of mode density, ``the vapor component'' of the model. The mass of the inflaton is occasioned by the exchange of degrees of freedom between the ``vapor'' and the ``liquid'', the planckian ``soup'' in which usual ``cisplanckian'' fields propagate. This exchange between vacuum fluctuations is modeled after its counterpart in the real world i.e. black hole evaporation. In order of magnitude, a very rough semiquantitative estimate, would situate the mass somewhere between $10^{-10}$ and $10^{-5}$ planck masses, the largest uncertainty being the mass of the planckian black hole fluctuation i.e. the entropy that one ascribes to it. |
gr-qc/0608135 | Etera R. Livine | Etera R. Livine | Towards a Covariant Loop Quantum Gravity | 13 pages, review, draft chapter for the book "Approaches to quantum
gravity", being prepared by Daniele Oriti for Cambridge University Press,
comments welcome | null | null | null | gr-qc hep-th | null | We review the canonical analysis of the Palatini action without going to the
time gauge as in the standard derivation of Loop Quantum Gravity. This allows
to keep track of the Lorentz gauge symmetry and leads to a theory of Covariant
Loop Quantum Gravity. This new formulation does not suffer from the Immirzi
ambiguity, it has a continuous area spectrum and uses spin networks for the
Lorentz group. Finally, its dynamics can easily be related to Barrett-Crane
like spin foam models.
| [
{
"created": "Wed, 30 Aug 2006 18:50:02 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Livine",
"Etera R.",
""
]
] | We review the canonical analysis of the Palatini action without going to the time gauge as in the standard derivation of Loop Quantum Gravity. This allows to keep track of the Lorentz gauge symmetry and leads to a theory of Covariant Loop Quantum Gravity. This new formulation does not suffer from the Immirzi ambiguity, it has a continuous area spectrum and uses spin networks for the Lorentz group. Finally, its dynamics can easily be related to Barrett-Crane like spin foam models. |
2010.05830 | Marta Colleoni | Marta Colleoni, Maite Mateu-Lucena, H\'ector Estell\'es, Cecilio
Garc\'ia-Quir\'os, David Keitel, Geraint Pratten, Antoni Ramos-Buades, Sascha
Husa | Towards the routine use of subdominant harmonics in gravitational-wave
inference: re-analysis of GW190412 with generation X waveform models | 25 pages, 18 figures. Data release:
https://doi.org/10.5281/zenodo.4079188 | Phys. Rev. D 103, 024029 (2021) | 10.1103/PhysRevD.103.024029 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We re-analyse the gravitational-wave event GW190412 with state-of-the-art
phenomenological waveform models. This event, which has been associated with a
black hole merger, is interesting due to the significant contribution from
subdominant harmonics. We use both frequency-domain and time-domain waveform
models. The PhenomX waveform models constitute the fourth generation of
frequency-domain phenomenological waveforms for black hole binary coalescence;
they have more recently been complemented by the time-domain PhenomT models,
which open up new strategies to model precession and eccentricity, and to
perform tests of general relativity with the phenomenological waveforms
approach. Both PhenomX and PhenomT have been constructed with similar
techniques and accuracy goals, and due to their computational efficiency this
"generation X" model family allows the routine use of subdominant spherical
harmonics in Bayesian inference. We show the good agreement between these and
other state-of-the-art waveform models for GW190412, and discuss the
improvements over the previous generation of phenomenological waveform models.
We also discuss practical aspects of Bayesian inference such as run
convergence, variations of sampling parameters, and computational cost.
| [
{
"created": "Mon, 12 Oct 2020 16:25:46 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Oct 2020 15:45:17 GMT",
"version": "v2"
}
] | 2021-01-20 | [
[
"Colleoni",
"Marta",
""
],
[
"Mateu-Lucena",
"Maite",
""
],
[
"Estellés",
"Héctor",
""
],
[
"García-Quirós",
"Cecilio",
""
],
[
"Keitel",
"David",
""
],
[
"Pratten",
"Geraint",
""
],
[
"Ramos-Buades",
"Antoni",... | We re-analyse the gravitational-wave event GW190412 with state-of-the-art phenomenological waveform models. This event, which has been associated with a black hole merger, is interesting due to the significant contribution from subdominant harmonics. We use both frequency-domain and time-domain waveform models. The PhenomX waveform models constitute the fourth generation of frequency-domain phenomenological waveforms for black hole binary coalescence; they have more recently been complemented by the time-domain PhenomT models, which open up new strategies to model precession and eccentricity, and to perform tests of general relativity with the phenomenological waveforms approach. Both PhenomX and PhenomT have been constructed with similar techniques and accuracy goals, and due to their computational efficiency this "generation X" model family allows the routine use of subdominant spherical harmonics in Bayesian inference. We show the good agreement between these and other state-of-the-art waveform models for GW190412, and discuss the improvements over the previous generation of phenomenological waveform models. We also discuss practical aspects of Bayesian inference such as run convergence, variations of sampling parameters, and computational cost. |
gr-qc/0510118 | Manfred Droste | Manfred Droste | Universal homogeneous causal sets | 14 pages | J.Math.Phys. 46 (2005) 122503 | 10.1063/1.2147607 | null | gr-qc | null | Causal sets are particular partially ordered sets which have been proposed as
a basic model for discrete space-time in quantum gravity. We show that the
class C of all countable past-finite causal sets contains a unique causal set
(U,<) which is universal (i.e., any member of C can be embedded into (U,<)) and
homogeneous (i.e., (U,<) has maximal degree of symmetry). Moreover, (U,<) can
be constructed both probabilistically and explicitly. In contrast, the larger
class of all countable causal sets does not contain a universal object.
| [
{
"created": "Fri, 28 Oct 2005 13:50:01 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Droste",
"Manfred",
""
]
] | Causal sets are particular partially ordered sets which have been proposed as a basic model for discrete space-time in quantum gravity. We show that the class C of all countable past-finite causal sets contains a unique causal set (U,<) which is universal (i.e., any member of C can be embedded into (U,<)) and homogeneous (i.e., (U,<) has maximal degree of symmetry). Moreover, (U,<) can be constructed both probabilistically and explicitly. In contrast, the larger class of all countable causal sets does not contain a universal object. |
gr-qc/9712020 | John Barrow | John D. Barrow | Limits on Cosmological Magnetic Fields and Other Anisotropic Stresses | 28 pages, Tex file, no figures. Proceedings 4th Paris Cosmology
Colloquium, Paris June 1997, ed H. de Vega, and N. Sanchez | null | null | null | gr-qc astro-ph | null | We discuss the cosmological evolution of matter sources with small
anisotropic pressures. This includes electric and magnetic fields,
collisionless relativistic particles, gravitons, antisymmetric axion fields in
low-energy string cosmologies, spatial curvature anisotropies, and stresses
arising from simple topological defects. The COBE microwave sky maps are used
to place strong limits on the possible contribution of these sources to the
total density of the universe. We explain why the limits obtained from
primordial nucleosynthesis are generally weaker than those imposed by the
microwave background isotropy. The effect of inflation on all these stresses is
also calculated.
| [
{
"created": "Wed, 3 Dec 1997 02:56:50 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Barrow",
"John D.",
""
]
] | We discuss the cosmological evolution of matter sources with small anisotropic pressures. This includes electric and magnetic fields, collisionless relativistic particles, gravitons, antisymmetric axion fields in low-energy string cosmologies, spatial curvature anisotropies, and stresses arising from simple topological defects. The COBE microwave sky maps are used to place strong limits on the possible contribution of these sources to the total density of the universe. We explain why the limits obtained from primordial nucleosynthesis are generally weaker than those imposed by the microwave background isotropy. The effect of inflation on all these stresses is also calculated. |
1807.09721 | Andronikos Paliathanasis | Leonidas Karpathopoulos, Michael Tsamparlis and Andronikos
Paliathanasis | Quadratic conservation laws and collineations: a discussion | 10 pages, no figures, to appear in JGP | null | 10.1016/j.geomphys.2018.07.017 | null | gr-qc math-ph math.CA math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Every second order system of autonomous differential equations can be
described by an autonomous holonomic dynamical system with a Lagrangian part,
an effective potential and a set of generalized forces. The kinematic part of
the Lagrangian defines the kinetic metric which subsequently defines a
Riemannian geometry in the configuration space. We consider the generic
function $I=K_{ab}(t,q^{c})\dot{q}^{a}\dot{q}^{b}+K_{a}(t,q^{c})\dot{q}%
^{a}+K(t,q^{c})$ and require the quadratic first integral condition $dI/dt=0$
without involving any type of symmetry Lie or Noether. Condition $dI/dt=0$
leads to a system of equations involving the coefficients $K_{ab}%
(t,q^{c}),K_{a}(t,q^{c}),K(t,q^{c})$ whose solution will produce all possible
quadratic first integrals of the original system of autonomous differential
equations. We show that the new system of equations relates the quadratic first
integrals of the holonomic system with the geometric collineations of the
kinetic metric and in particular with the Killing tensors of order two. We
consider briefly various results concerning the Killing tensors of second-order
and prove a general formula which gives in the case of a flat kinetic metric
the generic Killing tensor in terms of the vectors of the special projective
algebra of the kinetic metric. This establishes the connection between the
geometry defined by the kinetic metric and the quadratic first integrals of the
original system of differential equations.
| [
{
"created": "Wed, 25 Jul 2018 16:57:25 GMT",
"version": "v1"
}
] | 2018-09-26 | [
[
"Karpathopoulos",
"Leonidas",
""
],
[
"Tsamparlis",
"Michael",
""
],
[
"Paliathanasis",
"Andronikos",
""
]
] | Every second order system of autonomous differential equations can be described by an autonomous holonomic dynamical system with a Lagrangian part, an effective potential and a set of generalized forces. The kinematic part of the Lagrangian defines the kinetic metric which subsequently defines a Riemannian geometry in the configuration space. We consider the generic function $I=K_{ab}(t,q^{c})\dot{q}^{a}\dot{q}^{b}+K_{a}(t,q^{c})\dot{q}% ^{a}+K(t,q^{c})$ and require the quadratic first integral condition $dI/dt=0$ without involving any type of symmetry Lie or Noether. Condition $dI/dt=0$ leads to a system of equations involving the coefficients $K_{ab}% (t,q^{c}),K_{a}(t,q^{c}),K(t,q^{c})$ whose solution will produce all possible quadratic first integrals of the original system of autonomous differential equations. We show that the new system of equations relates the quadratic first integrals of the holonomic system with the geometric collineations of the kinetic metric and in particular with the Killing tensors of order two. We consider briefly various results concerning the Killing tensors of second-order and prove a general formula which gives in the case of a flat kinetic metric the generic Killing tensor in terms of the vectors of the special projective algebra of the kinetic metric. This establishes the connection between the geometry defined by the kinetic metric and the quadratic first integrals of the original system of differential equations. |
1807.01997 | Mayeul Arminjon | Mayeul Arminjon | Is spacetime as physical as is space? | 25 pages | Journal of Geometry and Symmetry in Physics, Vol. 46, pp. 1-24
(2017) | 10.7546/jgsp-46-2017-1-24 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Two questions are investigated by looking successively at classical
mechanics, special relativity, and relativistic gravity: first, how is space
related with spacetime? The proposed answer is that each given reference fluid,
that is a congruence of reference trajectories, defines a physical space. The
points of that space are formally defined to be the world lines of the
congruence. That space can be endowed with a natural structure of 3-D
differentiable manifold, thus giving rise to a simple notion of spatial tensor
--- namely, a tensor on the space manifold. The second question is: does the
geometric structure of the spacetime determine the physics, in particular, does
it determine its relativistic or preferred-frame character? We find that it
does not, for different physics (either relativistic or not) may be defined on
the same spacetime structure --- and also, the same physics can be implemented
on different spacetime structures.
Keywords: Affine space; classical mechanics; special relativity; relativistic
gravity; reference fluid.
| [
{
"created": "Wed, 4 Jul 2018 13:59:59 GMT",
"version": "v1"
}
] | 2018-07-06 | [
[
"Arminjon",
"Mayeul",
""
]
] | Two questions are investigated by looking successively at classical mechanics, special relativity, and relativistic gravity: first, how is space related with spacetime? The proposed answer is that each given reference fluid, that is a congruence of reference trajectories, defines a physical space. The points of that space are formally defined to be the world lines of the congruence. That space can be endowed with a natural structure of 3-D differentiable manifold, thus giving rise to a simple notion of spatial tensor --- namely, a tensor on the space manifold. The second question is: does the geometric structure of the spacetime determine the physics, in particular, does it determine its relativistic or preferred-frame character? We find that it does not, for different physics (either relativistic or not) may be defined on the same spacetime structure --- and also, the same physics can be implemented on different spacetime structures. Keywords: Affine space; classical mechanics; special relativity; relativistic gravity; reference fluid. |
2010.08424 | Farhad Darabi | F. Darabi, M. Golmohammadi, and A. Rezaei-Aghdam | (2+1)-dimensional f(R) gravity solutions via Hojman symmetry | 17 pages, minor revisions | Int. J. Geom. Methods Mod. Phys, Vol. 19, No. 04, 2250057 (2022) | 10.1142/S0219887822500578 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we use the Hojman symmetry approach to find new
$(2+1)$-dimensional $f(R)$ gravity solutions, in comparison to Noether symmetry
approach. In the special case of Hojman symmetry vector $X=R$, we recover
$(2+1)$-dimensional BTZ black hole and generalized $(2+1)$-dimensional BTZ
black hole solutions, obtained by Noether symmetry approach, and the
interesting point is that the cosmological constant is appeared as the direct
manifestation of Hojman symmetry.
| [
{
"created": "Fri, 16 Oct 2020 14:41:10 GMT",
"version": "v1"
},
{
"created": "Sun, 11 Apr 2021 08:44:34 GMT",
"version": "v2"
},
{
"created": "Sat, 26 Mar 2022 10:23:06 GMT",
"version": "v3"
}
] | 2022-03-29 | [
[
"Darabi",
"F.",
""
],
[
"Golmohammadi",
"M.",
""
],
[
"Rezaei-Aghdam",
"A.",
""
]
] | In this paper, we use the Hojman symmetry approach to find new $(2+1)$-dimensional $f(R)$ gravity solutions, in comparison to Noether symmetry approach. In the special case of Hojman symmetry vector $X=R$, we recover $(2+1)$-dimensional BTZ black hole and generalized $(2+1)$-dimensional BTZ black hole solutions, obtained by Noether symmetry approach, and the interesting point is that the cosmological constant is appeared as the direct manifestation of Hojman symmetry. |
1601.01625 | Hao Wei | Shoulong Li, Hao Wei | Stability of Differentially Rotating Disks in $f(T)$ Theory | 16 pages, 1 figure, revtex4; v2: discussions added, Gen. Rel. Grav.
in press; v3: published version | Gen. Rel. Grav. 48 (2016) 150 | 10.1007/s10714-016-2146-y | null | gr-qc astro-ph.CO astro-ph.GA hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | To explain the accelerated expansion of our universe, many dark energy models
and modified gravity theories have been proposed so far. It is argued in the
literature that they are difficult to be distinguished on the cosmological
scales. Therefore, it is well motivated to consider the relevant astrophysical
phenomena on (or below) the galactic scales. In this work, we study the
stability of self-gravitating differentially rotating galactic disks in $f(T)$
theory, and obtain the local stability criteria in $f(T)$ theory, which are
valid for all $f(T)$ theories satisfying $f(T=0)=0$ and $f_T (T=0)\not=0$, if
the adiabatic approximation and the weak field limit are considered. The
information of the function $f(T)$ is mainly encoded in the parameter
$\alpha\equiv 1/f_T(T=0)$. We find that the local stability criteria in $f(T)$
theory are quite different from the ones in Newtonian gravity, general
relativity, and other modified gravity theories such as $f(R)$ theory. We
consider that this might be a possible hint to distinguish $f(T)$ theory from
general relativity and other modified gravity theories on (or below) the
galactic scales.
| [
{
"created": "Thu, 7 Jan 2016 18:00:00 GMT",
"version": "v1"
},
{
"created": "Sat, 8 Oct 2016 03:19:00 GMT",
"version": "v2"
},
{
"created": "Mon, 24 Oct 2016 03:11:00 GMT",
"version": "v3"
}
] | 2016-10-25 | [
[
"Li",
"Shoulong",
""
],
[
"Wei",
"Hao",
""
]
] | To explain the accelerated expansion of our universe, many dark energy models and modified gravity theories have been proposed so far. It is argued in the literature that they are difficult to be distinguished on the cosmological scales. Therefore, it is well motivated to consider the relevant astrophysical phenomena on (or below) the galactic scales. In this work, we study the stability of self-gravitating differentially rotating galactic disks in $f(T)$ theory, and obtain the local stability criteria in $f(T)$ theory, which are valid for all $f(T)$ theories satisfying $f(T=0)=0$ and $f_T (T=0)\not=0$, if the adiabatic approximation and the weak field limit are considered. The information of the function $f(T)$ is mainly encoded in the parameter $\alpha\equiv 1/f_T(T=0)$. We find that the local stability criteria in $f(T)$ theory are quite different from the ones in Newtonian gravity, general relativity, and other modified gravity theories such as $f(R)$ theory. We consider that this might be a possible hint to distinguish $f(T)$ theory from general relativity and other modified gravity theories on (or below) the galactic scales. |
gr-qc/0610004 | Gregory M. Harry | Gregory M. Harry, Matthew R. Abernathy, Andres E. Becerra-Toledo,
Helena Armandula, Eric Black, Kate Dooley, Matt Eichenfield, Chinyere
Nwabugwu, Akira Villar, D. R. M. Crooks, Gianpietro Cagnoli, Jim Hough, Colin
R. How, Ian MacLaren, Peter Murray, Stuart Reid, Sheila Rowan, Peter H.
Sneddon, Martin M Fejer, Roger Route, Steven D. Penn, Patrick Ganau,
Jean-Marie Mackowski, Christophe Michel, Laurent Pinard, Alban Remillieux | Titania-doped tantala/silica coatings for gravitational-wave detection | null | Class.Quant.Grav.24:405-416,2007 | 10.1088/0264-9381/24/2/008 | null | gr-qc | null | Reducing thermal noise from optical coatings is crucial to reaching the
required sensitivity in next generation interferometric gravitational-waves
detectors. Here we show that adding TiO$_2$ to Ta$_2$O$_5$ in
Ta$_2$O$_5$/SiO$_2$ coatings reduces the internal friction and in addition
present data confirming it reduces thermal noise. We also show that
TiO$_2$-doped Ta$_2$O$_5$/SiO$_2$ coatings are close to satisfying the optical
absorption requirements of second generation gravitational-wave detectors.
| [
{
"created": "Sun, 1 Oct 2006 20:47:34 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Harry",
"Gregory M.",
""
],
[
"Abernathy",
"Matthew R.",
""
],
[
"Becerra-Toledo",
"Andres E.",
""
],
[
"Armandula",
"Helena",
""
],
[
"Black",
"Eric",
""
],
[
"Dooley",
"Kate",
""
],
[
"Eichenfield",
"Matt",
... | Reducing thermal noise from optical coatings is crucial to reaching the required sensitivity in next generation interferometric gravitational-waves detectors. Here we show that adding TiO$_2$ to Ta$_2$O$_5$ in Ta$_2$O$_5$/SiO$_2$ coatings reduces the internal friction and in addition present data confirming it reduces thermal noise. We also show that TiO$_2$-doped Ta$_2$O$_5$/SiO$_2$ coatings are close to satisfying the optical absorption requirements of second generation gravitational-wave detectors. |
1101.0863 | Yurii Ignatyev | Yu.G. Ignatyev | Magnetohydrodynamic Equations in a Gravitational Field and Excitation of
Magnetohydrodynamic Shock Waves by a Gravitational Wave | 28 pages, 19 references, 1 table | Gravitation & Cosmology, Vol. 1 (1995), No. 4, pp. 287-300 | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | On the basis of simple principles we derive and investigate the equations of
relativistic plasma magnetohydrodynamics (MHD) in an arbitrary gravitational
field. An exact solution describing the motion of magnetoactive plasma against
the background of the metric of a plane gravitational wave (PGW) with an
arbitrary amplitude is obtained. It is shown that in strong magnetic fields
even a sufficiently small amplitude PGW can create a shock MHD wave,
propagating at a subluminal velocity. Astrophysical consequences of the
anomalous plasma acceleration are considered.
| [
{
"created": "Wed, 5 Jan 2011 01:09:32 GMT",
"version": "v1"
}
] | 2011-01-06 | [
[
"Ignatyev",
"Yu. G.",
""
]
] | On the basis of simple principles we derive and investigate the equations of relativistic plasma magnetohydrodynamics (MHD) in an arbitrary gravitational field. An exact solution describing the motion of magnetoactive plasma against the background of the metric of a plane gravitational wave (PGW) with an arbitrary amplitude is obtained. It is shown that in strong magnetic fields even a sufficiently small amplitude PGW can create a shock MHD wave, propagating at a subluminal velocity. Astrophysical consequences of the anomalous plasma acceleration are considered. |
1501.06306 | Ayesha Zakria | Ayesha Zakria, Mubasher Jamil | Center of Mass Energy of the Collision for Two General Geodesic
Particles Around a Kerr-Newman-Taub-NUT Black Hole | 23 pages, 7 figures, 2 tables, Accepted in JHEP | JHEP 05 : 147 (2015) | 10.1007/JHEP05(2015)147 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate the center of mass energy of the collision for
two neutral particles with different rest masses falling freely from rest at
infinity in the background of a Kerr-Newman-Taub-NUT black hole. Further, we
discuss the center of mass energy near the horizon(s) of an extremal and
non-extremal Kerr-Newman-Taub-NUT black hole and show that an arbitrarily high
center of mass energy is achievable under some restrictions. We will study the
special case of the center of mass energy when the specific energy, specific
angular momentum and Carter constant of both the particles are same.
| [
{
"created": "Mon, 26 Jan 2015 10:11:52 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Mar 2015 19:04:56 GMT",
"version": "v2"
},
{
"created": "Sun, 10 May 2015 12:49:59 GMT",
"version": "v3"
}
] | 2015-06-01 | [
[
"Zakria",
"Ayesha",
""
],
[
"Jamil",
"Mubasher",
""
]
] | In this paper, we investigate the center of mass energy of the collision for two neutral particles with different rest masses falling freely from rest at infinity in the background of a Kerr-Newman-Taub-NUT black hole. Further, we discuss the center of mass energy near the horizon(s) of an extremal and non-extremal Kerr-Newman-Taub-NUT black hole and show that an arbitrarily high center of mass energy is achievable under some restrictions. We will study the special case of the center of mass energy when the specific energy, specific angular momentum and Carter constant of both the particles are same. |
2208.15002 | Kelly MacDevette | Kelly MacDevette, Peter Dunsby, Saikat Chakraborty | A comprehensive analysis of the compact phase space for Hu-Sawicki
$f(R)$ dark energy models including spatial curvature | 23 pages, 9 figures | null | 10.1103/PhysRevD.106.103533 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | We present a comprehensive dynamical systems analysis of homogeneous and
isotropic Friedmann-La\^{i}matre-Robertson-Walker cosmologies in the Hu-Sawicki
$f(R)$ dark energy model for the parameter choice $\{n,C_1\}=\{1,1\}$. For a
generic $f(R)$ theory, we outline the procedures of compactification of the
phase space, which in general is 4-dimensional. We also outline how, given an
$f(R)$ model, one can determine the coordinate of the phase space point that
corresponds to the present day universe and the equation of a surface in the
phase space that represents the $\Lambda$CDM evolution history. Next, we apply
these procedures to the Hu-Sawicki model under consideration. We identify some
novel features of the phase space of the model such as the existence of
invariant submanifolds and 2-dimensional sheets of fixed points. We determine
the physically viable region of the phase space, the fixed point corresponding
to possible matter dominated epochs and discuss the possibility of a
non-singular bounce, re-collapse and cyclic evolution. We also provide a
numerical analysis comparing the $\Lambda$CDM evolution and the Hu-Sawicki
evolution.
| [
{
"created": "Wed, 31 Aug 2022 17:59:23 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Oct 2022 11:28:28 GMT",
"version": "v2"
}
] | 2022-12-07 | [
[
"MacDevette",
"Kelly",
""
],
[
"Dunsby",
"Peter",
""
],
[
"Chakraborty",
"Saikat",
""
]
] | We present a comprehensive dynamical systems analysis of homogeneous and isotropic Friedmann-La\^{i}matre-Robertson-Walker cosmologies in the Hu-Sawicki $f(R)$ dark energy model for the parameter choice $\{n,C_1\}=\{1,1\}$. For a generic $f(R)$ theory, we outline the procedures of compactification of the phase space, which in general is 4-dimensional. We also outline how, given an $f(R)$ model, one can determine the coordinate of the phase space point that corresponds to the present day universe and the equation of a surface in the phase space that represents the $\Lambda$CDM evolution history. Next, we apply these procedures to the Hu-Sawicki model under consideration. We identify some novel features of the phase space of the model such as the existence of invariant submanifolds and 2-dimensional sheets of fixed points. We determine the physically viable region of the phase space, the fixed point corresponding to possible matter dominated epochs and discuss the possibility of a non-singular bounce, re-collapse and cyclic evolution. We also provide a numerical analysis comparing the $\Lambda$CDM evolution and the Hu-Sawicki evolution. |
1802.03306 | Peter Tsun Ho Pang | Peter T. H. Pang, Juan Calder\'on Bustillo, Yifan Wang and Tjonnie G.
F. Li | On the Potential Observation of False Deviations from General Relativity
in Gravitational Wave Observations from Binary Black Holes | 11 pages, 7 figures | Phys. Rev. D 98, 024019 (2018) | 10.1103/PhysRevD.98.024019 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Detections of gravitational waves emitted by binary black holes allow for
tests of General Relativity in the strong-field regime. In particular,
deviations from General Relativity can be observed by comparing incoming
signals to waveform templates that include parametrized deviations from General
Relativity. However, it is essential that the General Relativity sector of
these templates accounts for all predictable physics. Otherwise, missing
physics might be mimicked by the "beyond General Relativity" sector of the
templates, leading the analysis to report apparent deviations from General
Relativity. Current parametrized tests implement templates that omit physical
phenomena such as orbital eccentricity and higher-order modes. In this paper,
we show how the omission of higher modes can lead to false deviations from
General Relativity when these effects are strong enough. We study the extent of
these deviations as a function of the mass ratio and the orbital orientation.
We find that significant false deviations can arise when current tests are
performed on signals emitted by asymmetric binaries whose orbital angular
momentum is orthogonal to the line-of-sight. We estimate that the Advanced
LIGO-Virgo network operating at its design sensitivity can observe false
violations with a significance above $5 \sigma$ as often as once per year.
Similar results are expected for other tests of General Relativity that use
modified waveform models. Hence, we stress the necessity of accurate waveform
models that include physical effects such as higher-order modes to trust future
tests of General Relativity.
| [
{
"created": "Fri, 9 Feb 2018 15:33:58 GMT",
"version": "v1"
}
] | 2018-08-07 | [
[
"Pang",
"Peter T. H.",
""
],
[
"Bustillo",
"Juan Calderón",
""
],
[
"Wang",
"Yifan",
""
],
[
"Li",
"Tjonnie G. F.",
""
]
] | Detections of gravitational waves emitted by binary black holes allow for tests of General Relativity in the strong-field regime. In particular, deviations from General Relativity can be observed by comparing incoming signals to waveform templates that include parametrized deviations from General Relativity. However, it is essential that the General Relativity sector of these templates accounts for all predictable physics. Otherwise, missing physics might be mimicked by the "beyond General Relativity" sector of the templates, leading the analysis to report apparent deviations from General Relativity. Current parametrized tests implement templates that omit physical phenomena such as orbital eccentricity and higher-order modes. In this paper, we show how the omission of higher modes can lead to false deviations from General Relativity when these effects are strong enough. We study the extent of these deviations as a function of the mass ratio and the orbital orientation. We find that significant false deviations can arise when current tests are performed on signals emitted by asymmetric binaries whose orbital angular momentum is orthogonal to the line-of-sight. We estimate that the Advanced LIGO-Virgo network operating at its design sensitivity can observe false violations with a significance above $5 \sigma$ as often as once per year. Similar results are expected for other tests of General Relativity that use modified waveform models. Hence, we stress the necessity of accurate waveform models that include physical effects such as higher-order modes to trust future tests of General Relativity. |
gr-qc/0604079 | Sujitkumar Chatterjee | D. Panigrahi, Y.Z.Zhang and S.Chatterjee | Accelerating Universe as Window for Extra Dimensions | 20 pages,3 figures | Int.J.Mod.Phys. A21 (2006) 6491-6512 | 10.1142/S0217751X06034318 | null | gr-qc | null | Homogeneous cosmological solutions are obtained in five dimensional space
time assuming equations of state $ p = k\rho $ and $ p_{5}= \gamma\rho$ where p
is the isotropic 3 - pressure and $p_{5}$, that for the fifth dimension. Using
different values for the constants k and $\gamma$ many known solutions are
rediscovered. Further the current acceleration of the universe has led us to
investigate higher dimensional gravity theory, which is able to explain
acceleration from a theoretical view point without the need of introducing dark
energy by hand. We argue that the terms containing higher dimensional metric
coefficients produce an extra negative pressure that apparently drives an
acceleration of the 3D space, tempting us to suggest that the accelerating
universe seems to act as a window to the existence of extra spatial dimensions.
Interestingly the 5D matter field remains regular while the \emph{effective}
negative pressure is responsible for the inflation. Relaxing the assumptions of
two equations of state we also present a class of solutions which provide early
deceleration followed by a late acceleration in a unified manner. Interesting
to point out that in this case our cosmology apparently mimics the well known
quintessence scenario fuelled by a generalised Chaplygin-type of fluid where a
smooth transition from a dust dominated model to a de Sitter like one takes
place.
| [
{
"created": "Wed, 19 Apr 2006 12:18:31 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Sep 2006 14:31:11 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Panigrahi",
"D.",
""
],
[
"Zhang",
"Y. Z.",
""
],
[
"Chatterjee",
"S.",
""
]
] | Homogeneous cosmological solutions are obtained in five dimensional space time assuming equations of state $ p = k\rho $ and $ p_{5}= \gamma\rho$ where p is the isotropic 3 - pressure and $p_{5}$, that for the fifth dimension. Using different values for the constants k and $\gamma$ many known solutions are rediscovered. Further the current acceleration of the universe has led us to investigate higher dimensional gravity theory, which is able to explain acceleration from a theoretical view point without the need of introducing dark energy by hand. We argue that the terms containing higher dimensional metric coefficients produce an extra negative pressure that apparently drives an acceleration of the 3D space, tempting us to suggest that the accelerating universe seems to act as a window to the existence of extra spatial dimensions. Interestingly the 5D matter field remains regular while the \emph{effective} negative pressure is responsible for the inflation. Relaxing the assumptions of two equations of state we also present a class of solutions which provide early deceleration followed by a late acceleration in a unified manner. Interesting to point out that in this case our cosmology apparently mimics the well known quintessence scenario fuelled by a generalised Chaplygin-type of fluid where a smooth transition from a dust dominated model to a de Sitter like one takes place. |
gr-qc/0512146 | Robert Carroll | Robert Carroll | Remarks on the WDW equation | 15 pages, Latex 2e | null | null | null | gr-qc | null | We show a kind of converse to some results of Hall and Reginatto on exact
uncertainty related to the Schroedinger and Wheeler-deWitt equations. Some
survey material on statistical geometrodynamics is also sketched.
| [
{
"created": "Mon, 26 Dec 2005 14:11:26 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Carroll",
"Robert",
""
]
] | We show a kind of converse to some results of Hall and Reginatto on exact uncertainty related to the Schroedinger and Wheeler-deWitt equations. Some survey material on statistical geometrodynamics is also sketched. |
gr-qc/0702032 | Yun Soo Myung | Yun Soo Myung | Black hole and holographic dark energy | 11pages, 1 figure, version to appear in PLB | Phys.Lett.B649:247-251,2007 | 10.1016/j.physletb.2007.04.026 | INJE-TP-07-01 | gr-qc | null | We discuss the connection between black hole and holographic dark energy. We
examine the issue of the equation of state (EOS) for holographic energy density
as a candidate for the dark energy carefully. This is closely related to the
EOS for black hole, because the holographic dark energy comes from the black
hole energy density. In order to derive the EOS of a black hole, we may use its
dual (quantum) systems. Finally, a regular black hole without the singularity
is introduced to describe an accelerating universe inside the cosmological
horizon. Inspired by this, we show that the holographic energy density with the
cosmological horizon as the IR cutoff leads to the dark energy-dominated
universe with $\omega_{\rm \Lambda}=-1$.
| [
{
"created": "Tue, 6 Feb 2007 02:27:19 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Apr 2007 00:45:12 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Myung",
"Yun Soo",
""
]
] | We discuss the connection between black hole and holographic dark energy. We examine the issue of the equation of state (EOS) for holographic energy density as a candidate for the dark energy carefully. This is closely related to the EOS for black hole, because the holographic dark energy comes from the black hole energy density. In order to derive the EOS of a black hole, we may use its dual (quantum) systems. Finally, a regular black hole without the singularity is introduced to describe an accelerating universe inside the cosmological horizon. Inspired by this, we show that the holographic energy density with the cosmological horizon as the IR cutoff leads to the dark energy-dominated universe with $\omega_{\rm \Lambda}=-1$. |
1805.06394 | Niccol\'o Loret | Niccol\'o Loret, Leonardo Barcaroli, Giulia Gubitosi | Quantum Gravity phenomenology and metric formalism | null | null | 10.1142/9789813226609_0534 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this proceedings for the MG14 conference, we discuss the construction of a
phenomenology of Planck-scale effects in curved spacetimes, underline a few
open issues and describe some perspectives for the future of this research
line.
| [
{
"created": "Wed, 16 May 2018 16:05:30 GMT",
"version": "v1"
}
] | 2019-02-27 | [
[
"Loret",
"Niccoló",
""
],
[
"Barcaroli",
"Leonardo",
""
],
[
"Gubitosi",
"Giulia",
""
]
] | In this proceedings for the MG14 conference, we discuss the construction of a phenomenology of Planck-scale effects in curved spacetimes, underline a few open issues and describe some perspectives for the future of this research line. |
gr-qc/0508120 | Claus Kiefer | Claus Kiefer | Quantum Gravity: General Introduction and Recent Developments | 21 pages, 6 figures, invited contribution for "Annalen der Physik",
v2: minor corrections, additional references | Annalen Phys. 15 (2005) 129-148 | 10.1002/andp.200510175 | null | gr-qc hep-th | null | I briefly review the current status of quantum gravity. After giving some
general motivations for the need of such a theory, I discuss the main
approaches in quantizing general relativity: Covariant approaches (perturbation
theory, effective theory, and path integrals) and canonical approaches (quantum
geometrodynamics, loop quantum gravity). I then address quantum gravitational
aspects of string theory. This is followed by a discussion of black holes and
quantum cosmology. I end with some remarks on the observational status of
quantum gravity.
| [
{
"created": "Mon, 29 Aug 2005 15:32:38 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Sep 2005 07:15:47 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Kiefer",
"Claus",
""
]
] | I briefly review the current status of quantum gravity. After giving some general motivations for the need of such a theory, I discuss the main approaches in quantizing general relativity: Covariant approaches (perturbation theory, effective theory, and path integrals) and canonical approaches (quantum geometrodynamics, loop quantum gravity). I then address quantum gravitational aspects of string theory. This is followed by a discussion of black holes and quantum cosmology. I end with some remarks on the observational status of quantum gravity. |
gr-qc/0105020 | Gregory M. Harry | Gregory M Harry, Janet L Houser, Kenneth A Strain | Comparison of advanced gravitational-wave detectors | null | Phys.Rev. D65 (2002) 082001 | 10.1103/PhysRevD.65.082001 | null | gr-qc | null | We compare two advanced designs for gravitational-wave antennas in terms of
their ability to detect two possible gravitational wave sources. Spherical,
resonant mass antennas and interferometers incorporating resonant sideband
extraction (RSE) were modeled using experimentally measurable parameters. The
signal-to-noise ratio of each detector for a binary neutron star system and a
rapidly rotating stellar core were calculated. For a range of plausible
parameters we found that the advanced LIGO interferometer incorporating RSE
gave higher signal-to-noise ratios than a spherical detector resonant at the
same frequency for both sources. Spheres were found to be sensitive to these
sources at distances beyond our galaxy. Interferometers were sensitive to these
sources at far enough distances that several events per year would be expected.
| [
{
"created": "Fri, 4 May 2001 21:42:49 GMT",
"version": "v1"
},
{
"created": "Fri, 8 Jun 2001 22:09:25 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Harry",
"Gregory M",
""
],
[
"Houser",
"Janet L",
""
],
[
"Strain",
"Kenneth A",
""
]
] | We compare two advanced designs for gravitational-wave antennas in terms of their ability to detect two possible gravitational wave sources. Spherical, resonant mass antennas and interferometers incorporating resonant sideband extraction (RSE) were modeled using experimentally measurable parameters. The signal-to-noise ratio of each detector for a binary neutron star system and a rapidly rotating stellar core were calculated. For a range of plausible parameters we found that the advanced LIGO interferometer incorporating RSE gave higher signal-to-noise ratios than a spherical detector resonant at the same frequency for both sources. Spheres were found to be sensitive to these sources at distances beyond our galaxy. Interferometers were sensitive to these sources at far enough distances that several events per year would be expected. |
1203.0754 | Vitaliy Voytik | Vitaliy V. Voytik | About Lorentz-M{\o}ller-Nelson transformation to rigid noninertial frame
of reference | 47 pages, in Russian, added subsection about connection between the
proper Thomas precession and the Wigner rotation, revised section 10,
corrected typos | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | With a special Lorentz-M{\o}ller-Nelson (LMN) transformation found
transformation of velocity from the laboratory system S to an accelerated,
rotating frame of reference s. The physical sense of parameter entering into
the LMN special transformation is established. For small distances, and their
proper smooth motion without jerks suggested the inverse special LMN
transformation. The main consequences of this transformation is considered,
namely, a) the desync in moving frame of reference s of proper clocks of the
pre-synchronized in the laboratory frame S and b) the Lorentz contraction of
proper rulers of frame s in the frame S. The applicability of the inverse LMN
transformation for real frames with maximum rigidity is established. Equations
for the rotation matrix is obtained. It is shown that the intrinsic rotation of
the axes s, considered with respect to S is not rigid. Found the direct and
inverse transformation of affine "angular" velocity in the S to the comoving,
but not rotating frame s. Also shown that for the non-inertial motion of
rigidly rotating frame of reference her the kinematic deformation of
coordinates system is absent in two planes. The application of this
transformation to a rotating rigid body is considered. The matrice and angle of
proper Wigner rotation is calculated. We find differential equations for the
inverse problem of relativistic kinematics, and their decision in the case of
uniformly accelerated motion. The close connection between the proper Thomas
precession and the proper Wigner rotation and their mutual compensation for the
case uniformly accelerated motion has shown. The difference of the uniformly
accelerated motion from the hyperbolic one has been shown. Also, the basic
formulas are expressed in terms of the parameter, which is solution of the
equation for the inverse problem of relativistic kinematics.
| [
{
"created": "Sun, 4 Mar 2012 17:41:37 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Jun 2012 15:21:04 GMT",
"version": "v2"
}
] | 2012-06-04 | [
[
"Voytik",
"Vitaliy V.",
""
]
] | With a special Lorentz-M{\o}ller-Nelson (LMN) transformation found transformation of velocity from the laboratory system S to an accelerated, rotating frame of reference s. The physical sense of parameter entering into the LMN special transformation is established. For small distances, and their proper smooth motion without jerks suggested the inverse special LMN transformation. The main consequences of this transformation is considered, namely, a) the desync in moving frame of reference s of proper clocks of the pre-synchronized in the laboratory frame S and b) the Lorentz contraction of proper rulers of frame s in the frame S. The applicability of the inverse LMN transformation for real frames with maximum rigidity is established. Equations for the rotation matrix is obtained. It is shown that the intrinsic rotation of the axes s, considered with respect to S is not rigid. Found the direct and inverse transformation of affine "angular" velocity in the S to the comoving, but not rotating frame s. Also shown that for the non-inertial motion of rigidly rotating frame of reference her the kinematic deformation of coordinates system is absent in two planes. The application of this transformation to a rotating rigid body is considered. The matrice and angle of proper Wigner rotation is calculated. We find differential equations for the inverse problem of relativistic kinematics, and their decision in the case of uniformly accelerated motion. The close connection between the proper Thomas precession and the proper Wigner rotation and their mutual compensation for the case uniformly accelerated motion has shown. The difference of the uniformly accelerated motion from the hyperbolic one has been shown. Also, the basic formulas are expressed in terms of the parameter, which is solution of the equation for the inverse problem of relativistic kinematics. |
1904.01563 | Emmanuil Saridakis | Spyros Basilakos, Genly Leon, G. Papagiannopoulos, Emmanuel N.
Saridakis | Dynamical system analysis at background and perturbation levels:
Quintessence in severe disadvantage comparing to $\Lambda$CDM | 5 pages, 1 figure, 3 tables, version accepted in Phys. Rev. D | Phys. Rev. D 100, 043524 (2019) | 10.1103/PhysRevD.100.043524 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform for the first time a dynamical system analysis of both the
background and perturbation equations, of $\Lambda$CDM cosmology and
quintessence scenario with an exponential potential. In the former case the
perturbations do not change the stability of the late-time attractor of the
background equations, and the system still results in the dark-energy
dominated, de Sitter solution, having passed from the correct dark-matter era
with $\gamma\approx6/11$. However, in the case of quintessence the
incorporation of perturbations changes the stability and properties of the
background evolution, and the only conditionally stable points present either
an exponentially increasing matter clustering not favored by observations, or
Laplacian instabilities, and thus not physically interesting. This result is a
severe disadvantage of quintessence cosmology comparing to $\Lambda$CDM
paradigm.
| [
{
"created": "Tue, 2 Apr 2019 17:39:26 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Aug 2019 06:59:53 GMT",
"version": "v2"
},
{
"created": "Mon, 19 Aug 2019 03:24:25 GMT",
"version": "v3"
}
] | 2019-08-21 | [
[
"Basilakos",
"Spyros",
""
],
[
"Leon",
"Genly",
""
],
[
"Papagiannopoulos",
"G.",
""
],
[
"Saridakis",
"Emmanuel N.",
""
]
] | We perform for the first time a dynamical system analysis of both the background and perturbation equations, of $\Lambda$CDM cosmology and quintessence scenario with an exponential potential. In the former case the perturbations do not change the stability of the late-time attractor of the background equations, and the system still results in the dark-energy dominated, de Sitter solution, having passed from the correct dark-matter era with $\gamma\approx6/11$. However, in the case of quintessence the incorporation of perturbations changes the stability and properties of the background evolution, and the only conditionally stable points present either an exponentially increasing matter clustering not favored by observations, or Laplacian instabilities, and thus not physically interesting. This result is a severe disadvantage of quintessence cosmology comparing to $\Lambda$CDM paradigm. |
0912.2761 | Oded Hod | Shahar Hod and Oded Hod | Comment on "The extremal black hole bomb" | 2 pages, 1 figure | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, we have provided an analytical treatment of the phenomena known as
the 'black-hole bomb' (arXiv:0910.0734). In particular, we have determined
analytically the unstable growing resonances of a massive scalar field in the
rotating Kerr black hole spacetime. It was later claimed by J. G. Rosa
(arXiv:0912.1780) that the analytic procedure may fail for some values of the
field's mass. This claim was based on the concern that some of the Gamma
functions that are involved in the analysis may develop poles. In this comment
we show by explicit calculations that the Gamma functions which are used are
all well behaved near the peak of the black-hole resonances. This fact supports
the validity of our previous analytical treatment. We further comment on the
regime of validity of some of the approximations used by Rosa.
| [
{
"created": "Mon, 14 Dec 2009 21:47:19 GMT",
"version": "v1"
}
] | 2009-12-17 | [
[
"Hod",
"Shahar",
""
],
[
"Hod",
"Oded",
""
]
] | Recently, we have provided an analytical treatment of the phenomena known as the 'black-hole bomb' (arXiv:0910.0734). In particular, we have determined analytically the unstable growing resonances of a massive scalar field in the rotating Kerr black hole spacetime. It was later claimed by J. G. Rosa (arXiv:0912.1780) that the analytic procedure may fail for some values of the field's mass. This claim was based on the concern that some of the Gamma functions that are involved in the analysis may develop poles. In this comment we show by explicit calculations that the Gamma functions which are used are all well behaved near the peak of the black-hole resonances. This fact supports the validity of our previous analytical treatment. We further comment on the regime of validity of some of the approximations used by Rosa. |
1609.04037 | Andrea Nerozzi | Andrea Nerozzi | Spin coefficients and gauge fixing in the Newman-Penrose formalism | 12 pages, to match version published in PRD | Phys. Rev. D 95, 064012 (2017) | 10.1103/PhysRevD.95.064012 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Since its introduction in 1962, the Newman-Penrose formalism has been widely
used in analytical and numerical studies of Einstein's equations, like for
example for the Teukolsky master equation, or as a powerful wave extraction
tool in numerical relativity. Despite the many applications, Einstein's
equations in the Newman-Penrose formalism appear complicated and not easily
applicable to general studies of spacetimes, mainly because physical and gauge
degrees of freedom are mixed in a nontrivial way. In this paper we approach the
whole formalism with the goal of expressing the spin coefficients as functions
of tetrad invariants once a particular tetrad is chosen. We show that it is
possible to do so, and give for the first time a general recipe for the task,
as well as an indication of the quantities and identities that are required.
| [
{
"created": "Tue, 13 Sep 2016 20:27:22 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Mar 2017 00:27:48 GMT",
"version": "v2"
}
] | 2017-03-10 | [
[
"Nerozzi",
"Andrea",
""
]
] | Since its introduction in 1962, the Newman-Penrose formalism has been widely used in analytical and numerical studies of Einstein's equations, like for example for the Teukolsky master equation, or as a powerful wave extraction tool in numerical relativity. Despite the many applications, Einstein's equations in the Newman-Penrose formalism appear complicated and not easily applicable to general studies of spacetimes, mainly because physical and gauge degrees of freedom are mixed in a nontrivial way. In this paper we approach the whole formalism with the goal of expressing the spin coefficients as functions of tetrad invariants once a particular tetrad is chosen. We show that it is possible to do so, and give for the first time a general recipe for the task, as well as an indication of the quantities and identities that are required. |
2104.01895 | Ragab Gad | Ragab M Gad and H. A. Alharbi | Gravitational Energy in Van Stockum Space-Time | 16 pages No figures, Accepted for publication in Indian journal of
physics (2021) | null | 10.1007/s12648-021-02085-2 | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | The purpose of this paper is to illustrate the problem of energy and momentum
distributions of Van Stockum space-time within the framework of two different
theories of gravity, general relativity and teleparallel gravity.
We have shown that for all homogeneous space-times with metric components
$g_{\mu\nu}$ being functions of time variable, $t$, alone and independent of
space variables the total gravitational energy for any finite volume is
identically zero. By working with general relativity, we have calculated the
energy-momentum density for Van Stockum space-time using double index complexes
and in the framework teleparallel gravity, we used the energy-momentum
complexes of Einstein, Bergmann-Thomson and Landau-Lifshitz. In our analysis,
we sustained that general relativity and teleparallel gravity are equivalent
theories of space-time under consideration. For space-time under consideration,
we have shown that different complexes of energy-momentum density do not
provide the same results neither in general relativity nor in teleparallel
gravity.
| [
{
"created": "Fri, 2 Apr 2021 11:49:33 GMT",
"version": "v1"
}
] | 2021-05-26 | [
[
"Gad",
"Ragab M",
""
],
[
"Alharbi",
"H. A.",
""
]
] | The purpose of this paper is to illustrate the problem of energy and momentum distributions of Van Stockum space-time within the framework of two different theories of gravity, general relativity and teleparallel gravity. We have shown that for all homogeneous space-times with metric components $g_{\mu\nu}$ being functions of time variable, $t$, alone and independent of space variables the total gravitational energy for any finite volume is identically zero. By working with general relativity, we have calculated the energy-momentum density for Van Stockum space-time using double index complexes and in the framework teleparallel gravity, we used the energy-momentum complexes of Einstein, Bergmann-Thomson and Landau-Lifshitz. In our analysis, we sustained that general relativity and teleparallel gravity are equivalent theories of space-time under consideration. For space-time under consideration, we have shown that different complexes of energy-momentum density do not provide the same results neither in general relativity nor in teleparallel gravity. |
gr-qc/0312100 | Achilles D. Speliotopoulos | Raymond Y. Chiao and A. D. Speliotopoulos | A Crystal-based Matter-wave Interferometric Gravitational-wave
Observatory | Nineteen pages with two figures. Written using RevTeX. To appear in,
"Quantum Aspects of Beam Physics", ed. by P. Chen (World Scientific,
Singapore, 2004). Typographical errors corrected and acknowledgements added | null | 10.1142/9789812702333_0025 | null | gr-qc astro-ph hep-th physics.atom-ph | null | It is shown that atom interferometry allows for the construction of MIGO, the
Matter-wave Interferometric Gravitational-wave Observatory. MIGOs of the same
sensitivity as LIGO or LISA are expected to be orders of magnitude smaller than
either one. A design for MIGO using crystalline diffraction gratings is
introduced, and its sensitivity is calculated.
| [
{
"created": "Mon, 22 Dec 2003 20:57:01 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Dec 2003 22:07:50 GMT",
"version": "v2"
},
{
"created": "Fri, 26 Dec 2003 18:21:38 GMT",
"version": "v3"
}
] | 2017-08-23 | [
[
"Chiao",
"Raymond Y.",
""
],
[
"Speliotopoulos",
"A. D.",
""
]
] | It is shown that atom interferometry allows for the construction of MIGO, the Matter-wave Interferometric Gravitational-wave Observatory. MIGOs of the same sensitivity as LIGO or LISA are expected to be orders of magnitude smaller than either one. A design for MIGO using crystalline diffraction gratings is introduced, and its sensitivity is calculated. |
1901.02674 | K Haris | O.A. Hannuksela, K. Haris, K.K.Y. Ng, S. Kumar, A.K. Mehta, D. Keitel,
T.G.F. Li and P. Ajith | Search for gravitational lensing signatures in LIGO-Virgo binary black
hole events | 9 pages, 6 figures. Longer discussion on the marginal events | Astrophysical Journal Letters 874:L2 (2019) | 10.3847/2041-8213/ab0c0f | LIGO-P1800297 | gr-qc astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We search for signatures of gravitational lensing in the binary black hole
events detected by Advanced LIGO and Virgo during their first two observational
runs. In particular, we look for three effects: 1) evidence of lensing
magnification in the individual signals due to galaxy lenses, 2) evidence of
multiple images due to strong lensing by galaxies, 3) evidence of wave optics
effects due to point-mass lenses. We find no compelling evidence of any of
these signatures in the observed gravitational wave signals. However, as the
sensitivities of gravitational wave detectors improve in the future, detecting
lensed events may become quite likely.
| [
{
"created": "Wed, 9 Jan 2019 11:00:38 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Jan 2019 12:07:22 GMT",
"version": "v2"
}
] | 2019-06-03 | [
[
"Hannuksela",
"O. A.",
""
],
[
"Haris",
"K.",
""
],
[
"Ng",
"K. K. Y.",
""
],
[
"Kumar",
"S.",
""
],
[
"Mehta",
"A. K.",
""
],
[
"Keitel",
"D.",
""
],
[
"Li",
"T. G. F.",
""
],
[
"Ajith",
"P.",
... | We search for signatures of gravitational lensing in the binary black hole events detected by Advanced LIGO and Virgo during their first two observational runs. In particular, we look for three effects: 1) evidence of lensing magnification in the individual signals due to galaxy lenses, 2) evidence of multiple images due to strong lensing by galaxies, 3) evidence of wave optics effects due to point-mass lenses. We find no compelling evidence of any of these signatures in the observed gravitational wave signals. However, as the sensitivities of gravitational wave detectors improve in the future, detecting lensed events may become quite likely. |
1308.1543 | Behrouz Mirza | Seyed Ali Hosseini Mansoori, Behrouz Mirza | Correspondence of phase transition points and singularities of
thermodynamic geometry of black holes | 10 pages, 4 figures, typos fixed, references added | Eur. Phys. J. C (2014) 74:2681 | 10.1140/epjc/s10052-013-2681-6 | null | gr-qc cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore a formulation of thermodynamic geometry of black holes and prove
that the divergent points of the specific heat correspond exactly to the
singularities of the thermodynamic curvature. We investigate this
correspondence for different types of black holes. This formulation can also be
applied to an arbitrary thermodynamic system.
| [
{
"created": "Wed, 7 Aug 2013 11:54:47 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Feb 2014 15:04:33 GMT",
"version": "v2"
}
] | 2014-02-06 | [
[
"Mansoori",
"Seyed Ali Hosseini",
""
],
[
"Mirza",
"Behrouz",
""
]
] | We explore a formulation of thermodynamic geometry of black holes and prove that the divergent points of the specific heat correspond exactly to the singularities of the thermodynamic curvature. We investigate this correspondence for different types of black holes. This formulation can also be applied to an arbitrary thermodynamic system. |
1212.1324 | Manoelito M. de Souza | Manoelito M de Souza | Gravity from Discrete Interactions, a laboratory of ideas for field
theory | 11 pages, 2 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The observed accelerated expansion of the universe is an indication that
somehow, in some conditions, gravity may become a repulsive interaction. The
very concept of discrete interactions, compatible with General Relativity as an
effective theory of averaged fields, can handle this and other pressing
problems without the need of searching for ad hoc exotic sources. Semi-quantum
models of discrete interactions based on quantum exchanges between point-like
masses are a rich laboratory for enlightening field interactions and
classical-to-quantum transitions in field theory. A very simple version is
presented for exhibiting how naturally it makes contact with inflation, dark
matter and dark energy issues.
| [
{
"created": "Thu, 6 Dec 2012 13:31:47 GMT",
"version": "v1"
}
] | 2012-12-07 | [
[
"de Souza",
"Manoelito M",
""
]
] | The observed accelerated expansion of the universe is an indication that somehow, in some conditions, gravity may become a repulsive interaction. The very concept of discrete interactions, compatible with General Relativity as an effective theory of averaged fields, can handle this and other pressing problems without the need of searching for ad hoc exotic sources. Semi-quantum models of discrete interactions based on quantum exchanges between point-like masses are a rich laboratory for enlightening field interactions and classical-to-quantum transitions in field theory. A very simple version is presented for exhibiting how naturally it makes contact with inflation, dark matter and dark energy issues. |
1702.08412 | Dennis Philipp | Dennis Philipp, Volker Perlick, Dirk Puetzfeld, Eva Hackmann, Claus
L\"ammerzahl | Definition of the relativistic geoid in terms of isochronometric
surfaces | 24 pages, 7 figures; improved figures, references added | Phys. Rev. D 95, 104037 (2017) | 10.1103/PhysRevD.95.104037 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a definition of the geoid that is based on the formalism of
general relativity without approximations; i.e. it allows for arbitrarily
strong gravitational fields. For this reason, it applies not only to the Earth
and other planets but also to compact objects such as neutron stars. We define
the geoid as a level surface of a time-independent redshift potential. Such a
redshift potential exists in any stationary spacetime. Therefore, our geoid is
well defined for any rigidly rotating object with constant angular velocity and
a fixed rotation axis that is not subject to external forces. Our definition is
operational because the level surfaces of a redshift potential can be realized
with the help of standard clocks, which may be connected by optical fibers.
Therefore, these surfaces are also called isochronometric surfaces. We
deliberately base our definition of a relativistic geoid on the use of clocks
since we believe that clock geodesy offers the best methods for probing
gravitational fields with highest precision in the future. However, we also
point out that our definition of the geoid is mathematically equivalent to a
definition in terms of an acceleration potential, i.e. that our geoid may also
be viewed as a level surface orthogonal to plumb lines. Moreover, we
demonstrate that our definition reduces to the known Newtonian and
post-Newtonian notions in the appropriate limits. As an illustration, we
determine the isochronometric surfaces for rotating observers in axisymmetric
static and axisymmetric stationary solutions to Einstein's vacuum field
equation, with the Schwarzschild metric, the Erez-Rosen metric, the q-metric
and the Kerr metric as particular examples.
| [
{
"created": "Mon, 27 Feb 2017 18:14:04 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Jun 2017 16:02:19 GMT",
"version": "v2"
}
] | 2017-06-07 | [
[
"Philipp",
"Dennis",
""
],
[
"Perlick",
"Volker",
""
],
[
"Puetzfeld",
"Dirk",
""
],
[
"Hackmann",
"Eva",
""
],
[
"Lämmerzahl",
"Claus",
""
]
] | We present a definition of the geoid that is based on the formalism of general relativity without approximations; i.e. it allows for arbitrarily strong gravitational fields. For this reason, it applies not only to the Earth and other planets but also to compact objects such as neutron stars. We define the geoid as a level surface of a time-independent redshift potential. Such a redshift potential exists in any stationary spacetime. Therefore, our geoid is well defined for any rigidly rotating object with constant angular velocity and a fixed rotation axis that is not subject to external forces. Our definition is operational because the level surfaces of a redshift potential can be realized with the help of standard clocks, which may be connected by optical fibers. Therefore, these surfaces are also called isochronometric surfaces. We deliberately base our definition of a relativistic geoid on the use of clocks since we believe that clock geodesy offers the best methods for probing gravitational fields with highest precision in the future. However, we also point out that our definition of the geoid is mathematically equivalent to a definition in terms of an acceleration potential, i.e. that our geoid may also be viewed as a level surface orthogonal to plumb lines. Moreover, we demonstrate that our definition reduces to the known Newtonian and post-Newtonian notions in the appropriate limits. As an illustration, we determine the isochronometric surfaces for rotating observers in axisymmetric static and axisymmetric stationary solutions to Einstein's vacuum field equation, with the Schwarzschild metric, the Erez-Rosen metric, the q-metric and the Kerr metric as particular examples. |
gr-qc/0312013 | Amos Ori | Amos Ori | Harmonic-gauge dipole metric perturbations for weak-field circular
orbits in Schwarzschild spacetime | Latex | Phys.Rev. D70 (2004) 124027 | 10.1103/PhysRevD.70.124027 | null | gr-qc | null | We calculate the harmonic-gauge even l=1 mode of the linear metric
perturbation (MP) produced by a particle in a weak-field circular orbit around
a Schwarzschild black hole (BH). We focus on the Newtonian limit, i.e. the
limit in which the mass M of the central BH approaches zero (while fixing the
orbital radius and the small-object mass), and obtain explicit expressions for
the MP in this limit. We find that the MP are anomalous in this limit, namely,
they do not approach their standard, Coulomb-like, flat-space values. Instead,
the MP grows on approaching the BH, and this growth becomes worse as M
decreases. This anomalous behavior leads to some pathologies which we briefly
discuss. We also derive here the next-order correction (in the orbital
frequency $\Omega $) to the MP.
| [
{
"created": "Tue, 2 Dec 2003 09:00:11 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Ori",
"Amos",
""
]
] | We calculate the harmonic-gauge even l=1 mode of the linear metric perturbation (MP) produced by a particle in a weak-field circular orbit around a Schwarzschild black hole (BH). We focus on the Newtonian limit, i.e. the limit in which the mass M of the central BH approaches zero (while fixing the orbital radius and the small-object mass), and obtain explicit expressions for the MP in this limit. We find that the MP are anomalous in this limit, namely, they do not approach their standard, Coulomb-like, flat-space values. Instead, the MP grows on approaching the BH, and this growth becomes worse as M decreases. This anomalous behavior leads to some pathologies which we briefly discuss. We also derive here the next-order correction (in the orbital frequency $\Omega $) to the MP. |
gr-qc/9506019 | Coussaert Olivier | O. Coussaert, M. Henneaux and P. van Driel | The asymptotic dynamics of three-dimensional Einstein gravity with a
negative cosmological constant | 10 pages in LaTeX, LaTeX problem fixed | Class.Quant.Grav. 12 (1995) 2961-2966 | 10.1088/0264-9381/12/12/012 | ULB-TH/95/08 | gr-qc | null | Liouville theory is shown to describe the asymptotic dynamics of
three-dimensional Einstein gravity with a negative cosmological constant. This
is because (i) Chern-Simons theory with a gauge group $SL(2,R) \times SL(2,R)$
on a space-time with a cylindrical boundary is equivalent to the non-chiral
$SL(2,R)$ WZW model; and (ii) the anti-de Sitter boundary conditions implement
the constraints that reduce the WZW model to the Liouville theory.
| [
{
"created": "Thu, 8 Jun 1995 09:16:16 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Jun 1995 10:18:41 GMT",
"version": "v2"
}
] | 2009-10-28 | [
[
"Coussaert",
"O.",
""
],
[
"Henneaux",
"M.",
""
],
[
"van Driel",
"P.",
""
]
] | Liouville theory is shown to describe the asymptotic dynamics of three-dimensional Einstein gravity with a negative cosmological constant. This is because (i) Chern-Simons theory with a gauge group $SL(2,R) \times SL(2,R)$ on a space-time with a cylindrical boundary is equivalent to the non-chiral $SL(2,R)$ WZW model; and (ii) the anti-de Sitter boundary conditions implement the constraints that reduce the WZW model to the Liouville theory. |
1504.04695 | Sun Zhang | Sun Zhang | On Noether approach in the cosmological model with scalar and gauge
fields: symmetries and the selection rule | null | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, based on the works of Capozziello et al., we have studied the
Noether symmetry approach in the cosmological model with scalar and gauge
fields proposed recently by Soda et al. The correct Noether symmetries and
related Lie algebra are given according to the minisuperspace quantum
cosmological model. The Wheeler-De Witt (WDW) equation is presented after
quantization and the classical trajectories are then obtained in the
semi-classical limit. The oscillating features of the wave function in the
cosmic evolution recover the so-called Hartle criterion, and the selection rule
in minisuperspace quantum cosmology is strengthened. Then we have realized now
the proposition that Noether symmetries select classical universes.
| [
{
"created": "Sat, 18 Apr 2015 08:52:40 GMT",
"version": "v1"
}
] | 2015-04-21 | [
[
"Zhang",
"Sun",
""
]
] | In this paper, based on the works of Capozziello et al., we have studied the Noether symmetry approach in the cosmological model with scalar and gauge fields proposed recently by Soda et al. The correct Noether symmetries and related Lie algebra are given according to the minisuperspace quantum cosmological model. The Wheeler-De Witt (WDW) equation is presented after quantization and the classical trajectories are then obtained in the semi-classical limit. The oscillating features of the wave function in the cosmic evolution recover the so-called Hartle criterion, and the selection rule in minisuperspace quantum cosmology is strengthened. Then we have realized now the proposition that Noether symmetries select classical universes. |
2407.09569 | Bivudutta Mishra Dr. | Y. Kalpana Devi, S.A. Narawade, B. Mishra | Constraining Parameters for the Accelerating Universe in
$f(R,\mathcal{L}_{m})$ Gravity | 12 pages, 10 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the paper, we present an accelerating cosmological model in
$f(R,\mathcal{L}_{m})$ gravity with the parameter constrained through the
cosmological data sets. At the beginning, we have employed a functional form of
$f(R,\mathcal{L}_{m}) =\frac{R}{2}+\alpha R^2+\mathcal{L}_{m}^\beta$, where
$\alpha$ and $\beta$ are model parameters. This model is well motivated from
the Starobinsky model in $f(R)$ gravity and the power law form of
$f(\mathcal{L}_{m})$. The Hubble parameter has been derived with some algebraic
manipulation and constrained by Hubble data and Pantheon$^{+}$ data. With the
constraint parameters, present value of deceleration parameter has been
obtained to as $q_{0}\approx-0.63$ with the transition at $z_{t}\approx0.7$. It
shows the early deceleration and late time acceleration behaviour. The present
value of other geometric parameters such as the jerk and snap parameter are
obtained to be $j_{0}\approx0.78$ and $s_{0}\approx 0.1$ respectively. The
state finder diagnostic test gives the quintessence behaviour at present and
converging to $\Lambda$CDM at late times. Moreover the $Om(z)$ diagnostics
gives negative slope which shows that the model favours the state finder
diagnostic result. Also the current age of Universe has been obtained as,
$t_{0} = 13.64~~Gyrs$. The equation of state parameter also shows the
quintessence behaviour. Based on the present analysis, it indicates that the
$f(R,\mathcal{L}_{m})$ gravitational theory may be another alternative to study
the dark energy models.
| [
{
"created": "Tue, 9 Jul 2024 07:12:13 GMT",
"version": "v1"
}
] | 2024-07-16 | [
[
"Devi",
"Y. Kalpana",
""
],
[
"Narawade",
"S. A.",
""
],
[
"Mishra",
"B.",
""
]
] | In the paper, we present an accelerating cosmological model in $f(R,\mathcal{L}_{m})$ gravity with the parameter constrained through the cosmological data sets. At the beginning, we have employed a functional form of $f(R,\mathcal{L}_{m}) =\frac{R}{2}+\alpha R^2+\mathcal{L}_{m}^\beta$, where $\alpha$ and $\beta$ are model parameters. This model is well motivated from the Starobinsky model in $f(R)$ gravity and the power law form of $f(\mathcal{L}_{m})$. The Hubble parameter has been derived with some algebraic manipulation and constrained by Hubble data and Pantheon$^{+}$ data. With the constraint parameters, present value of deceleration parameter has been obtained to as $q_{0}\approx-0.63$ with the transition at $z_{t}\approx0.7$. It shows the early deceleration and late time acceleration behaviour. The present value of other geometric parameters such as the jerk and snap parameter are obtained to be $j_{0}\approx0.78$ and $s_{0}\approx 0.1$ respectively. The state finder diagnostic test gives the quintessence behaviour at present and converging to $\Lambda$CDM at late times. Moreover the $Om(z)$ diagnostics gives negative slope which shows that the model favours the state finder diagnostic result. Also the current age of Universe has been obtained as, $t_{0} = 13.64~~Gyrs$. The equation of state parameter also shows the quintessence behaviour. Based on the present analysis, it indicates that the $f(R,\mathcal{L}_{m})$ gravitational theory may be another alternative to study the dark energy models. |
1506.03897 | Vladimir Folomeev | Vladimir Dzhunushaliev, Vladimir Folomeev, and Ajnur Urazalina | Star-plus-wormhole systems with two interacting scalar fields | 10 pages, 3 figures, minor corrections to content, new references
added, version published in IJMPD. arXiv admin note: text overlap with
arXiv:1401.7093 | Int.J.Mod.Phys. D24 (2015) 14, 1550097 | 10.1142/S0218271815500972 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study static, spherically symmetric mixed configurations with a nontrivial
(wormhole) spacetime topology provided by the presence of two interacting ghost
scalar fields. Wormhole is assumed to be filled by a perfect relativistic
neutron fluid modeled by a polytropic equation of state. For such mixed
configurations, we find regular, asymptotically flat general relativistic
solutions. It is shown that the maximum of the fluid density is always shifted
from the center, and the resulting configurations represent, in general,
double-throat systems.
| [
{
"created": "Fri, 12 Jun 2015 05:10:51 GMT",
"version": "v1"
},
{
"created": "Sat, 5 Sep 2015 07:35:41 GMT",
"version": "v2"
}
] | 2015-09-08 | [
[
"Dzhunushaliev",
"Vladimir",
""
],
[
"Folomeev",
"Vladimir",
""
],
[
"Urazalina",
"Ajnur",
""
]
] | We study static, spherically symmetric mixed configurations with a nontrivial (wormhole) spacetime topology provided by the presence of two interacting ghost scalar fields. Wormhole is assumed to be filled by a perfect relativistic neutron fluid modeled by a polytropic equation of state. For such mixed configurations, we find regular, asymptotically flat general relativistic solutions. It is shown that the maximum of the fluid density is always shifted from the center, and the resulting configurations represent, in general, double-throat systems. |
1411.5154 | Titus K Mathew | Athira Sasidharan and Titus K. Mathew | Bulk viscous matter and recent acceleration of the Universe | 14 figures | EPJ C 75 348 2015 | 10.1140/epjc/s10052-015-3567-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a cosmological model dominated by bulk viscous matter with total
bulk viscosity coefficient proportional to the velocity and acceleration of the
expansion of the universe in such a way that
$\zeta=\zeta_{0}+\zeta_{1}\frac{\dot{a}}{a}+\zeta_{2}\frac{\ddot{a}}{\dot{a}}.$
We show that there exist two limiting conditions in the bulk viscous
coefficients, ($\zeta_{0}$, $\zeta_{1}$, $\zeta_{2}$) which corresponds to a
universe having a Big-Bang at the origin, followed by an early decelerated
epoch and then making a smooth transition into an accelerating epoch. We have
constrained the model using the type Ia Supernovae data, evaluated the best
estimated values of all the bulk viscous parameters and the Hubble parameter
corresponding to the two limiting conditions. We found that even though the
evolution of the cosmological parameters are in general different for the two
limiting cases, they show identical behavior for the best estimated values of
the parameters from both the limiting conditions. A recent acceleration would
occur if $\tilde{\zeta}_{0}+\tilde{\zeta}_{1}>1$ for the first limiting
conditions and if $\tilde{\zeta}_{0}+\tilde{\zeta}_{1}<1$ for the second
limiting conditions. The age of the universe predicted by this model is found
to be less than that predicted from the oldest galactic globular clusters. The
total bulk viscosity seems to be negative in the past and becomes positive when
$z\leq0.8$. So the model violates the local second law of thermodynamics.
However, the model satisfies the generalized second law of thermodynamics at
the apparent horizon throughout the evolution of the universe. We also made a
statefinder analysis of the model and found that it is distinguishably
different from the standard $\Lambda$CDM model at present, but shows a de
Sitter type behavior in the far future of the evolution.
| [
{
"created": "Wed, 19 Nov 2014 09:22:31 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Dec 2014 06:19:27 GMT",
"version": "v2"
},
{
"created": "Wed, 27 Apr 2016 05:34:47 GMT",
"version": "v3"
}
] | 2016-04-28 | [
[
"Sasidharan",
"Athira",
""
],
[
"Mathew",
"Titus K.",
""
]
] | We consider a cosmological model dominated by bulk viscous matter with total bulk viscosity coefficient proportional to the velocity and acceleration of the expansion of the universe in such a way that $\zeta=\zeta_{0}+\zeta_{1}\frac{\dot{a}}{a}+\zeta_{2}\frac{\ddot{a}}{\dot{a}}.$ We show that there exist two limiting conditions in the bulk viscous coefficients, ($\zeta_{0}$, $\zeta_{1}$, $\zeta_{2}$) which corresponds to a universe having a Big-Bang at the origin, followed by an early decelerated epoch and then making a smooth transition into an accelerating epoch. We have constrained the model using the type Ia Supernovae data, evaluated the best estimated values of all the bulk viscous parameters and the Hubble parameter corresponding to the two limiting conditions. We found that even though the evolution of the cosmological parameters are in general different for the two limiting cases, they show identical behavior for the best estimated values of the parameters from both the limiting conditions. A recent acceleration would occur if $\tilde{\zeta}_{0}+\tilde{\zeta}_{1}>1$ for the first limiting conditions and if $\tilde{\zeta}_{0}+\tilde{\zeta}_{1}<1$ for the second limiting conditions. The age of the universe predicted by this model is found to be less than that predicted from the oldest galactic globular clusters. The total bulk viscosity seems to be negative in the past and becomes positive when $z\leq0.8$. So the model violates the local second law of thermodynamics. However, the model satisfies the generalized second law of thermodynamics at the apparent horizon throughout the evolution of the universe. We also made a statefinder analysis of the model and found that it is distinguishably different from the standard $\Lambda$CDM model at present, but shows a de Sitter type behavior in the far future of the evolution. |
2401.04561 | Subhash Chandra Mahapatra | Ayan Daripa, Subhash Mahapatra | Analytic three-dimensional primary hair charged black holes with
Coulomb-like electrodynamics and their thermodynamics | 31 pages, many figures. arXiv admin note: text overlap with
arXiv:2305.09172 | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We construct and discuss new solutions of primary hair charged black holes in
asymptotically Anti-de Sitter (AdS) space that have well-defined Coulomb-like
potential in three dimensions. The gauge field source to the Einstein equation
is a power-Maxwell nonlinear electrodynamics with traceless energy-momentum
tensor. The coupled Einstein-power-Maxwell-scalar gravity system, which carries
the coupling $f(\phi)$ between the gauge and scalar fields, is analyzed, and
hairy charged black hole solutions are found analytically. We consider three
different profiles of the coupling functions: (i) $f(\phi)=1$, corresponding to
no direct coupling between the gauge and scalar fields, (ii)
$f(\phi)=e^{\phi}$, and (iii) $f(\phi)=e^{\phi^2/2}$, corresponding to their
non-minimal coupling. For all these cases, the scalar field, gauge fields, and
curvature scalars are regular and well-behaved everywhere outside the horizon.
We further study the thermodynamics of the obtained hairy black hole in the
canonical and grand-canonical ensembles and find significant changes in its
thermodynamic structure due to the scalar field. In particular, for all
considered coupling functions, the hairy parameter has a critical value above
which the hairy black hole undergoes the Hawking/Page phase transition, whereas
below which no such phase transition appears.
| [
{
"created": "Tue, 9 Jan 2024 13:57:37 GMT",
"version": "v1"
}
] | 2024-01-10 | [
[
"Daripa",
"Ayan",
""
],
[
"Mahapatra",
"Subhash",
""
]
] | We construct and discuss new solutions of primary hair charged black holes in asymptotically Anti-de Sitter (AdS) space that have well-defined Coulomb-like potential in three dimensions. The gauge field source to the Einstein equation is a power-Maxwell nonlinear electrodynamics with traceless energy-momentum tensor. The coupled Einstein-power-Maxwell-scalar gravity system, which carries the coupling $f(\phi)$ between the gauge and scalar fields, is analyzed, and hairy charged black hole solutions are found analytically. We consider three different profiles of the coupling functions: (i) $f(\phi)=1$, corresponding to no direct coupling between the gauge and scalar fields, (ii) $f(\phi)=e^{\phi}$, and (iii) $f(\phi)=e^{\phi^2/2}$, corresponding to their non-minimal coupling. For all these cases, the scalar field, gauge fields, and curvature scalars are regular and well-behaved everywhere outside the horizon. We further study the thermodynamics of the obtained hairy black hole in the canonical and grand-canonical ensembles and find significant changes in its thermodynamic structure due to the scalar field. In particular, for all considered coupling functions, the hairy parameter has a critical value above which the hairy black hole undergoes the Hawking/Page phase transition, whereas below which no such phase transition appears. |
2306.08898 | Alejandro Torres-Orjuela | Alejandro Torres-Orjuela | Detecting intermediate-mass black hole binaries with atom interferometer
observatories: Using the resonant mode for the merger phase | Submitted to 'AVS Quantum Science' for the special issue on "Large
Scale Quantum Detectors" | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by-nc-nd/4.0/ | Atom interferometry detectors like AION, ZAIGA, and AEDGE will be able to
detect gravitational waves (GWs) at dHz covering the band between large
space-based laser interferometers LISA/TianQin/Taiji and ground-based
facilities LIGO/Virgo/KAGRA. They will detect the late inspiral and merger of
GW sources containing intermediate-mass black holes (IMBHs) in the mass range
$10^2-10^5\,{\rm M_\odot}$. We study how accurately the parameters of an IMBH
binary can be measured using the noise curve of AION. Furthermore, we propose a
detection scheme where the early inspiral of the binary is detected using the
regular broadband mode while the merger is detected using the resonant mode. We
find that by using such a detection scheme the signal-to-noise ratio (SNR) of
the detection as well as the detection accuracy of the parameters can be
enhanced compared to the full detection of the signal using the broadband mode.
We, further, assess the impact of the necessary detection gap while switching
from broadband to resonant mode studying the case of a short ($30\,{\rm s}$)
and a long ($600\,{\rm s}$) gap. We find that the improvement in SNR and
detection accuracy is bigger for the shorter gap but that even in the case of
the long gap such a scheme can be beneficial.
| [
{
"created": "Thu, 15 Jun 2023 07:05:20 GMT",
"version": "v1"
}
] | 2023-06-16 | [
[
"Torres-Orjuela",
"Alejandro",
""
]
] | Atom interferometry detectors like AION, ZAIGA, and AEDGE will be able to detect gravitational waves (GWs) at dHz covering the band between large space-based laser interferometers LISA/TianQin/Taiji and ground-based facilities LIGO/Virgo/KAGRA. They will detect the late inspiral and merger of GW sources containing intermediate-mass black holes (IMBHs) in the mass range $10^2-10^5\,{\rm M_\odot}$. We study how accurately the parameters of an IMBH binary can be measured using the noise curve of AION. Furthermore, we propose a detection scheme where the early inspiral of the binary is detected using the regular broadband mode while the merger is detected using the resonant mode. We find that by using such a detection scheme the signal-to-noise ratio (SNR) of the detection as well as the detection accuracy of the parameters can be enhanced compared to the full detection of the signal using the broadband mode. We, further, assess the impact of the necessary detection gap while switching from broadband to resonant mode studying the case of a short ($30\,{\rm s}$) and a long ($600\,{\rm s}$) gap. We find that the improvement in SNR and detection accuracy is bigger for the shorter gap but that even in the case of the long gap such a scheme can be beneficial. |
2210.15007 | Mert Mangut | Mustafa Halilsoy, Mert Mangut and Chia-Li Hsieh | Stationary, charged Zipoy-Voorhees metric from colliding wave spacetime | A section has been added | General Relativity and Gravitation 2023 | 10.1007/s10714-023-03151-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Through the Ernst formalism we provide expression for a class of colliding
Einstein-Maxwell (EM) metrics with cross polarization. Local isometry is
imposed as a means to transform interaction region of the spacetime into
stationary, charged Zipoy-Voorhees (ZV) metric in Schwarzschild coordinates.
The ZV-metric is known to describe planetary/stellar objects with arbitrary
topology. "The world may be seen in a grain of sand" - William Blake.
| [
{
"created": "Wed, 26 Oct 2022 20:04:58 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Mar 2023 10:22:43 GMT",
"version": "v2"
},
{
"created": "Fri, 15 Sep 2023 18:35:37 GMT",
"version": "v3"
}
] | 2023-09-19 | [
[
"Halilsoy",
"Mustafa",
""
],
[
"Mangut",
"Mert",
""
],
[
"Hsieh",
"Chia-Li",
""
]
] | Through the Ernst formalism we provide expression for a class of colliding Einstein-Maxwell (EM) metrics with cross polarization. Local isometry is imposed as a means to transform interaction region of the spacetime into stationary, charged Zipoy-Voorhees (ZV) metric in Schwarzschild coordinates. The ZV-metric is known to describe planetary/stellar objects with arbitrary topology. "The world may be seen in a grain of sand" - William Blake. |
gr-qc/9607042 | null | Fran\c{c}ois Goy | Clock Synchronisation in Inertial Frames and Gravitational Fields | 4 pages, Latex; contribution to the Journees Relativistes, 1996 | null | null | null | gr-qc | null | The special relativistic test theory of Mansouri and Sexl is sketched.
Theories based on different clock synchronisations are found to be equivalent
to special relativity, as regards experimental results. The conventionality of
clock synchronisation is shown not to hold, by means of an example, in a simple
accelerated system and through the principle of equivalence in gravitational
fields, especially when the metric is not static. Experimental implications on
very precise clock synchronisation on earth are discussed.
| [
{
"created": "Sat, 20 Jul 1996 10:51:43 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Goy",
"François",
""
]
] | The special relativistic test theory of Mansouri and Sexl is sketched. Theories based on different clock synchronisations are found to be equivalent to special relativity, as regards experimental results. The conventionality of clock synchronisation is shown not to hold, by means of an example, in a simple accelerated system and through the principle of equivalence in gravitational fields, especially when the metric is not static. Experimental implications on very precise clock synchronisation on earth are discussed. |
1102.1749 | David McKechan | D. J. A. McKechan | On the use of higher order waveforms in the search for gravitational
waves emitted by compact binary coalescences | arXiv admin note: substantial text overlap with arXiv:1003.2939 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This thesis concerns the use, in gravitational wave data analysis, of higher
order waveform models of the gravitational radiation emitted by compact binary
coalescences. We begin with an introductory chapter that includes an overview
of the theory of general relativity, gravitational radiation and ground-based
interferometric gravitational wave detectors. We then discuss, in Chapter 2,
the gravitational waves emitted by compact binary coalescences, with an
explanation of higher order waveforms and how they differ from leading order
waveforms; we also introduce the post-Newtonian formalism. In Chapter 3 the
method and results of a gravitational wave search for low mass compact binary
coalescences using a subset of LIGO's 5th science run data are presented and in
the subsequent chapter we examine how one could use higher order waveforms in
such analyses. We follow the development of a new search algorithm that
incorporates higher order waveforms with promising results for detection
efficiency and parameter estimation. In Chapter 5, a new method of windowing
time-domain waveforms that offers benefit to gravitational wave searches is
presented. The final chapter covers the development of a game designed as an
outreach project to raise public awareness and understanding of the search for
gravitational waves.
| [
{
"created": "Tue, 8 Feb 2011 23:17:53 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Oct 2011 17:42:47 GMT",
"version": "v2"
}
] | 2015-03-18 | [
[
"McKechan",
"D. J. A.",
""
]
] | This thesis concerns the use, in gravitational wave data analysis, of higher order waveform models of the gravitational radiation emitted by compact binary coalescences. We begin with an introductory chapter that includes an overview of the theory of general relativity, gravitational radiation and ground-based interferometric gravitational wave detectors. We then discuss, in Chapter 2, the gravitational waves emitted by compact binary coalescences, with an explanation of higher order waveforms and how they differ from leading order waveforms; we also introduce the post-Newtonian formalism. In Chapter 3 the method and results of a gravitational wave search for low mass compact binary coalescences using a subset of LIGO's 5th science run data are presented and in the subsequent chapter we examine how one could use higher order waveforms in such analyses. We follow the development of a new search algorithm that incorporates higher order waveforms with promising results for detection efficiency and parameter estimation. In Chapter 5, a new method of windowing time-domain waveforms that offers benefit to gravitational wave searches is presented. The final chapter covers the development of a game designed as an outreach project to raise public awareness and understanding of the search for gravitational waves. |
gr-qc/9707037 | Michael A. Clayton | M.A. Clayton | Homothetic Wyman Spacetimes | 15 pages with 6 figures; requires amsart, amssymb, amsmath, graphicx;
formatted for publication in Int. J. Mod. Phys. D | Int.J.Mod.Phys. D7 (1998) 261-278 | 10.1142/S0218271898000218 | CERN--TH/97--166 | gr-qc | null | The time-dependent, spherically symmetric, Wyman sector of the Unified Field
Theory is shown to be equivalent to a self-gravitating scalar field with a
positive-definite, repulsive self-interaction potential. A homothetic symmetry
is imposed on the fundamental tensor, and the resulting autonomous system is
numerically integrated. Near the critical point (between the collapsing and
non-collapsing spacetimes) the system displays an approximately periodic
alternation between collapsing and dispersive epochs.
| [
{
"created": "Wed, 16 Jul 1997 14:57:53 GMT",
"version": "v1"
},
{
"created": "Wed, 15 Oct 1997 08:01:43 GMT",
"version": "v2"
}
] | 2009-10-30 | [
[
"Clayton",
"M. A.",
""
]
] | The time-dependent, spherically symmetric, Wyman sector of the Unified Field Theory is shown to be equivalent to a self-gravitating scalar field with a positive-definite, repulsive self-interaction potential. A homothetic symmetry is imposed on the fundamental tensor, and the resulting autonomous system is numerically integrated. Near the critical point (between the collapsing and non-collapsing spacetimes) the system displays an approximately periodic alternation between collapsing and dispersive epochs. |
1407.0125 | Haidar Sheikhahmadi | Haidar Sheikhahmadi, Ali Aghamohammadi and Khaled Saaidi | The effect of de Sitter like background on increasing the zero point
budget of dark energy | 11 pages, 3 figures | Advances in High Energy Physics, Volume 2016-05, Article ID
2594189, (2016) | 10.1155/2016/2594189 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | During this work, using subtraction renormalization mechanism, zero point
quantum fluctuations for bosonic scalar fields in a de-Sitter like background
are investigated. By virtue of the observed value for spectral index, $n_s(k)$,
for massive scalar field the best value for the first slow roll parameter,
$\epsilon$, is achieved. In addition the energy density of vacuum quantum
fluctuations for massless scalar field is obtained. The effects of these
fluctuations on other components of the Universe are studied. By solving the
conservation equation, for some different examples, the energy density for
different components of the Universe are obtained. In the case which, all
components of the Universe are in an interaction, the different dissipation
functions, $\tilde{Q}_{i}$, are considered. The time evolution of
${\rho_{DE}(z)}/{\rho_{cri}(z)}$ shows that $\tilde{Q}=3 \gamma H(t) \rho_{m}$
has best agreement in comparison to observational data including CMB, BAO and
SNeIa data set.
| [
{
"created": "Tue, 1 Jul 2014 07:35:32 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Jul 2014 09:21:29 GMT",
"version": "v2"
},
{
"created": "Sat, 5 Jul 2014 20:07:47 GMT",
"version": "v3"
},
{
"created": "Wed, 18 Feb 2015 09:53:19 GMT",
"version": "v4"
},
{
"crea... | 2016-06-13 | [
[
"Sheikhahmadi",
"Haidar",
""
],
[
"Aghamohammadi",
"Ali",
""
],
[
"Saaidi",
"Khaled",
""
]
] | During this work, using subtraction renormalization mechanism, zero point quantum fluctuations for bosonic scalar fields in a de-Sitter like background are investigated. By virtue of the observed value for spectral index, $n_s(k)$, for massive scalar field the best value for the first slow roll parameter, $\epsilon$, is achieved. In addition the energy density of vacuum quantum fluctuations for massless scalar field is obtained. The effects of these fluctuations on other components of the Universe are studied. By solving the conservation equation, for some different examples, the energy density for different components of the Universe are obtained. In the case which, all components of the Universe are in an interaction, the different dissipation functions, $\tilde{Q}_{i}$, are considered. The time evolution of ${\rho_{DE}(z)}/{\rho_{cri}(z)}$ shows that $\tilde{Q}=3 \gamma H(t) \rho_{m}$ has best agreement in comparison to observational data including CMB, BAO and SNeIa data set. |
2210.15633 | Virgo Publications | F. Acernese, M. Agathos, A. Ain, S. Albanesi, A. Allocca, A. Amato, T.
Andrade, N. Andres, M. Andr\'es-Carcasona, T. Andri\'c, S. Ansoldi, S.
Antier, T. Apostolatos, E. Z. Appavuravther, M. Ar\`ene, N. Arnaud, M.
Assiduo, S. Assis de Souza Melo, P. Astone, F. Aubin, S. Babak, F. Badaracco,
M. K. M. Bader, S. Bagnasco, J. Baird, T. Baka, G. Ballardin, G. Baltus, B.
Banerjee, C. Barbieri, P. Barneo, F. Barone, M. Barsuglia, D. Barta, A.
Basti, M. Bawaj, M. Bazzan, F. Beirnaert, M. Bejger, I. Belahcene, V.
Benedetto, M. Berbel, S. Bernuzzi, D. Bersanetti, A. Bertolini, U. Bhardwaj,
A. Bianchi, S. Bini, M. Bischi, M. Bitossi, M.-A. Bizouard, F. Bobba, M.
Bo\"er, G. Bogaert, M. Boldrini, L. D. Bonavena, F. Bondu, R. Bonnand, B. A.
Boom, V. Boschi, V. Boudart, Y. Bouffanais, A. Bozzi, C. Bradaschia, M.
Branchesi, M. Breschi, T. Briant, A. Brillet, J. Brooks, G. Bruno, F. Bucci,
T. Bulik, H. J. Bulten, D. Buskulic, C. Buy, G. S. Cabourn Davies, G. Cabras,
R. Cabrita, G. Cagnoli, E. Calloni, M. Canepa, S. Canevarolo, M.
Cannavacciuolo, E. Capocasa, G. Carapella, F. Carbognani, M. Carpinelli, G.
Carullo, J. Casanueva Diaz, C. Casentini, S. Caudill, F. Cavalier, R.
Cavalieri, G. Cella, P. Cerd\'a-Dur\'an, E. Cesarini, W. Chaibi, P. Chanial,
E. Chassande-Mottin, S. Chaty, F. Chiadini, G. Chiarini, R. Chierici, A.
Chincarini, M. L. Chiofalo, A. Chiummo, S. Choudhary, N. Christensen, G.
Ciani, P. Ciecielag, M. Cie\'slar, M. Cifaldi, R. Ciolfi, F. Cipriano, S.
Clesse, F. Cleva, E. Coccia, E. Codazzo, P.-F. Cohadon, D. E. Cohen, A.
Colombo, M. Colpi, L. Conti, I. Cordero-Carri\'on, S. Corezzi, D. Corre, S.
Cortese, J.-P. Coulon, M. Croquette, J. R. Cudell, E. Cuoco, M. Cury{\l}o, P.
Dabadie, T. Dal Canton, S. Dall'Osso, G. D\'alya, B. D'Angelo, S. Danilishin,
S. D'Antonio, V. Dattilo, M. Davier, D. Davis, J. Degallaix, M. De Laurentis,
S. Del\'eglise, F. De Lillo, D. Dell'Aquila, W. Del Pozzo, F. De Matteis, A.
Depasse, R. De Pietri, R. De Rosa, C. De Rossi, R. De Simone, L. Di Fiore, C.
Di Giorgio, F. Di Giovanni, M. Di Giovanni, T. Di Girolamo, A. Di Lieto, A.
Di Michele, S. Di Pace, I. Di Palma, F. Di Renzo, L. D'Onofrio, M. Drago,
J.-G. Ducoin, U. Dupletsa, O. Durante, D. D'Urso, P.-A. Duverne, M.
Eisenmann, L. Errico, D. Estevez, F. Fabrizi, F. Faedi, V. Fafone, S.
Farinon, G. Favaro, M. Fays, E. Fenyvesi, I. Ferrante, F. Fidecaro, P.
Figura, A. Fiori, I. Fiori, R. Fittipaldi, V. Fiumara, R. Flaminio, J. A.
Font, S. Frasca, F. Frasconi, A. Freise, O. Freitas, G. G. Fronz\'e, B. U.
Gadre, R. Gamba, B. Garaventa, F. Garufi, G. Gemme, A. Gennai, Archisman
Ghosh, B. Giacomazzo, L. Giacoppo, P. Giri, F. Gissi, S. Gkaitatzis, B.
Goncharov, M. Gosselin, R. Gouaty, A. Grado, M. Granata, V. Granata, G.
Greco, G. Grignani, A. Grimaldi, S. J. Grimm, P. Gruning, D. Guerra, G. M.
Guidi, G. Guix\'e, Y. Guo, P. Gupta, L. Haegel, O. Halim, O. Hannuksela, T.
Harder, K. Haris, J. Harms, B. Haskell, A. Heidmann, H. Heitmann, P. Hello,
G. Hemming, E. Hennes, S. Hild, D. Hofman, V. Hui, B. Idzkowski, A. Iess, P.
Iosif, T. Jacqmin, P.-E. Jacquet, S. P. Jadhav, J. Janquart, K. Janssens, P.
Jaranowski, V. Juste, C. Kalaghatgi, C. Karathanasis, S. Katsanevas, F.
K\'ef\'elian, N. Khetan, G. Koekoek, S. Koley, M. Kolstein, A. Kr\'olak, P.
Kuijer, P. Lagabbe, D. Laghi, M. Lalleman, A. Lamberts, I. La Rosa, A.
Lartaux-Vollard, C. Lazzaro, P. Leaci, A. Lema\^itre, M. Lenti, E. Leonova,
N. Leroy, N. Letendre, K. Leyde, F. Linde, L. London, A. Longo, M. Lopez
Portilla, M. Lorenzini, V. Loriette, G. Losurdo, D. Lumaca, A. Macquet, C.
Magazz\`u, M. Magnozzi, E. Majorana, I. Maksimovic, N. Man, V. Mangano, M.
Mantovani, M. Mapelli, F. Marchesoni, D. Mar\'in Pina, F. Marion, A.
Marquina, S. Marsat, F. Martelli, M. Martinez, V. Martinez, A. Masserot, S.
Mastrogiovanni, Q. Meijer, A. Menendez-Vazquez, L. Mereni, M. Merzougui, A.
Miani, C. Michel, L. Milano, A. Miller, B. Miller, E. Milotti, Y. Minenkov,
Ll. M. Mir, M. Miravet-Ten\'es, M. Montani, F. Morawski, B. Mours, C. M.
Mow-Lowry, S. Mozzon, F. Muciaccia, Suvodip Mukherjee, R. Musenich, A. Nagar,
V. Napolano, I. Nardecchia, H. Narola, L. Naticchioni, J. Neilson, C. Nguyen,
S. Nissanke, E. Nitoglia, F. Nocera, G. Oganesyan, C. Olivetto, G. Pagano, G.
Pagliaroli, C. Palomba, P. T. H. Pang, F. Pannarale, F. Paoletti, A. Paoli,
A. Paolone, G. Pappas, D. Pascucci, A. Pasqualetti, R. Passaquieti, D.
Passuello, B. Patricelli, R. Pedurand, M. Pegoraro, A. Perego, A. Pereira, C.
P\'erigois, A. Perreca, S. Perri\`es, D. Pesios, K. S. Phukon, O. J.
Piccinni, M. Pichot, M. Piendibene, F. Piergiovanni, L. Pierini, V. Pierro,
G. Pillant, M. Pillas, F. Pilo, L. Pinard, I. M. Pinto, M. Pinto, K.
Piotrzkowski, A. Placidi, E. Placidi, W. Plastino, R. Poggiani, E. Polini, E.
K. Porter, R. Poulton, M. Pracchia, T. Pradier, M. Principe, G. A. Prodi, P.
Prosposito, A. Puecher, M. Punturo, F. Puosi, P. Puppo, G. Raaijmakers, N.
Radulesco, P. Rapagnani, M. Razzano, T. Regimbau, L. Rei, P. Rettegno, B.
Revenu, A. Reza, F. Ricci, G. Riemenschneider, S. Rinaldi, F. Robinet, A.
Rocchi, L. Rolland, M. Romanelli, R. Romano, A. Romero, S. Ronchini, L. Rosa,
D. Rosi\'nska, S. Roy, D. Rozza, P. Ruggi, Jam. Sadiq, O. S. Salafia, L.
Salconi, F. Salemi, A. Samajdar, N. Sanchis-Gual, A. Sanuy, B. Sassolas, S.
Sayah, S. Schmidt, M. Seglar-Arroyo, D. Sentenac, V. Sequino, Y. Setyawati,
A. Sharma, N. S. Shcheblanov, M. Sieniawska, L. Silenzi, N. Singh, A. Singha,
V. Sipala, J. Soldateschi, K. Soni, V. Sordini, F. Sorrentino, N. Sorrentino,
R. Soulard, V. Spagnuolo, M. Spera, P. Spinicelli, C. Stachie, D. A. Steer,
J. Steinlechner, S. Steinlechner, N. Stergioulas, G. Stratta, M. Suchenek, A.
Sur, B. L. Swinkels, P. Szewczyk, M. Tacca, A. J. Tanasijczuk, E. N. Tapia
San Mart\'in, C. Taranto, A. E. Tolley, M. Tonelli, A. Torres-Forn\'e, I.
Tosta e Melo, A. Trapananti, F. Travasso, Max. Trevor, M. C. Tringali, L.
Troiano, A. Trovato, L. Trozzo, K. W. Tsang, K. Turbang, M. Turconi, A.
Utina, M. Valentini, N. van Bakel, M. van Beuzekom, M. van Dael, J. F. J. van
den Brand, C. Van Den Broeck, H. van Haevermaet, J. V. van Heijningen, N. van
Remortel, M. Vardaro, M. Vas\'uth, G. Vedovato, D. Verkindt, P. Verma, F.
Vetrano, A. Vicer\'e, V. Villa-Ortega, J.-Y. Vinet, A. Virtuoso, H. Vocca, R.
C. Walet, M. Was, A. R. Williamson, J. L. Willis, A. Zadro\.zny, T. Zelenova,
J.-P. Zendri | Virgo Detector Characterization and Data Quality: results from the O3
run | 57 pages, 18 figures. New version, resubmitted to Class. and Quantum
Grav. This is the "Results" part of preprint arXiv:2205.01555 [gr-qc] which
has been split into two companion articles: one about the tools and methods,
the other about the analyses of the O3 Virgo data | null | 10.1088/1361-6382/acd92d | null | gr-qc astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | The Advanced Virgo detector has contributed with its data to the rapid growth
of the number of detected gravitational-wave (GW) signals in the past few
years, alongside the two Advanced LIGO instruments. First during the last month
of the Observation Run 2 (O2) in August 2017 (with, most notably, the compact
binary mergers GW170814 and GW170817), and then during the full Observation Run
3 (O3): an 11-months data taking period, between April 2019 and March 2020,
that led to the addition of about 80 events to the catalog of transient GW
sources maintained by LIGO, Virgo and now KAGRA. These discoveries and the
manifold exploitation of the detected waveforms require an accurate
characterization of the quality of the data, such as continuous study and
monitoring of the detector noise sources. These activities, collectively named
{\em detector characterization and data quality} or {\em DetChar}, span the
whole workflow of the Virgo data, from the instrument front-end hardware to the
final analyses. They are described in details in the following article, with a
focus on the results achieved by the Virgo DetChar group during the O3 run.
Concurrently, a companion article describes the tools that have been used by
the Virgo DetChar group to perform this work.
| [
{
"created": "Fri, 14 Oct 2022 15:56:54 GMT",
"version": "v1"
},
{
"created": "Sat, 25 Mar 2023 16:25:57 GMT",
"version": "v2"
}
] | 2023-08-16 | [
[
"Acernese",
"F.",
""
],
[
"Agathos",
"M.",
""
],
[
"Ain",
"A.",
""
],
[
"Albanesi",
"S.",
""
],
[
"Allocca",
"A.",
""
],
[
"Amato",
"A.",
""
],
[
"Andrade",
"T.",
""
],
[
"Andres",
"N.",
""
... | The Advanced Virgo detector has contributed with its data to the rapid growth of the number of detected gravitational-wave (GW) signals in the past few years, alongside the two Advanced LIGO instruments. First during the last month of the Observation Run 2 (O2) in August 2017 (with, most notably, the compact binary mergers GW170814 and GW170817), and then during the full Observation Run 3 (O3): an 11-months data taking period, between April 2019 and March 2020, that led to the addition of about 80 events to the catalog of transient GW sources maintained by LIGO, Virgo and now KAGRA. These discoveries and the manifold exploitation of the detected waveforms require an accurate characterization of the quality of the data, such as continuous study and monitoring of the detector noise sources. These activities, collectively named {\em detector characterization and data quality} or {\em DetChar}, span the whole workflow of the Virgo data, from the instrument front-end hardware to the final analyses. They are described in details in the following article, with a focus on the results achieved by the Virgo DetChar group during the O3 run. Concurrently, a companion article describes the tools that have been used by the Virgo DetChar group to perform this work. |
0912.2327 | Betti Hartmann | Eva Hackmann, Betti Hartmann, Claus Laemmerzahl and Parinya Sirimachan | The complete set of solutions of the geodesic equations in the
space-time of a Schwarzschild black hole pierced by a cosmic string | 21 pages; section 3 shortened, references added; accepted for
publication in Phys. Rev. D | Phys.Rev.D81:064016,2010 | 10.1103/PhysRevD.81.064016 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the geodesic equations in the space-time of a Schwarzschild black
hole pierced by an infinitely thin cosmic string and give the complete set of
analytical solutions of these equations for massive and massless particles,
respectively. The solutions of the geodesic equations can be classified
according to the particle's energy and angular momentum, the ratio between the
component of the angular momentum aligned with the axis of the string and the
total angular momentum, the deficit angle of the space-time and as well the
horizon radius (or mass) of the black hole. For bound orbits of massive test
particles we calculate the perihelion shift, we discuss light deflection and
comment on the Newtonian limit.
| [
{
"created": "Fri, 11 Dec 2009 19:58:13 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Feb 2010 14:41:37 GMT",
"version": "v2"
}
] | 2010-04-21 | [
[
"Hackmann",
"Eva",
""
],
[
"Hartmann",
"Betti",
""
],
[
"Laemmerzahl",
"Claus",
""
],
[
"Sirimachan",
"Parinya",
""
]
] | We study the geodesic equations in the space-time of a Schwarzschild black hole pierced by an infinitely thin cosmic string and give the complete set of analytical solutions of these equations for massive and massless particles, respectively. The solutions of the geodesic equations can be classified according to the particle's energy and angular momentum, the ratio between the component of the angular momentum aligned with the axis of the string and the total angular momentum, the deficit angle of the space-time and as well the horizon radius (or mass) of the black hole. For bound orbits of massive test particles we calculate the perihelion shift, we discuss light deflection and comment on the Newtonian limit. |
gr-qc/0211060 | Sanjay Jhingan | Sanjay Jhingan and Takahiro Tanaka | Improvement on the metric reconstruction scheme in the
Regge-Wheeler-Zerilli formalism | New references added, 9 pages | Phys.Rev. D67 (2003) 104018 | 10.1103/PhysRevD.67.104018 | YITP-02-67 | gr-qc | null | We study master variables in the Regge-Wheeler-Zerilli formalism. We show
that a specific choice of new variables is suitable for studying perturbation
theory from the viewpoint of radiation reaction calculations. With explicit
definition of the improved master variables in terms of components of metric
perturbations, we present the master equations, with source terms, and metric
reconstruction formulas. In the scheme using these new variables, we do not
need any time and radial integrations except for solving the master equation.
We also show that the master variable for even parity modes which satisfies the
same homogeneous equation as the odd parity case, obtained via
Chandrasekhar transformation, does not have the good property in this sense.
| [
{
"created": "Mon, 18 Nov 2002 03:45:27 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Jun 2003 16:24:25 GMT",
"version": "v2"
}
] | 2016-08-31 | [
[
"Jhingan",
"Sanjay",
""
],
[
"Tanaka",
"Takahiro",
""
]
] | We study master variables in the Regge-Wheeler-Zerilli formalism. We show that a specific choice of new variables is suitable for studying perturbation theory from the viewpoint of radiation reaction calculations. With explicit definition of the improved master variables in terms of components of metric perturbations, we present the master equations, with source terms, and metric reconstruction formulas. In the scheme using these new variables, we do not need any time and radial integrations except for solving the master equation. We also show that the master variable for even parity modes which satisfies the same homogeneous equation as the odd parity case, obtained via Chandrasekhar transformation, does not have the good property in this sense. |
1011.4921 | Giovanni Marozzi Dr. | Giovanni Marozzi | The cosmological backreaction: gauge (in)dependence, observers and
scalars | 16 pages, no figures. Comments and references added, errors and typos
corrected, conclusions unchanged. Comment added and typos corrected, version
published in JCAP | JCAP 1101:012,2011 | 10.1088/1475-7516/2011/01/012 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss several issues related to a recent proposal for defining classical
spatial averages to be used in the so-called cosmological backreaction problem.
In the large averaging-volume limit all gauge dependence disappears and
different averages can be univocally characterized by the observers associated
with different scalar fields. The relation between such averaging procedure and
the standard one is emphasized and a gauge invariant way to select different
observers is presented. For finite averaging volumes we show that, within our
proposal, a residual gauge dependence is left, but is suppressed by several
effects.
| [
{
"created": "Mon, 22 Nov 2010 20:00:44 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Dec 2010 15:55:28 GMT",
"version": "v2"
},
{
"created": "Fri, 14 Jan 2011 17:36:36 GMT",
"version": "v3"
}
] | 2011-07-14 | [
[
"Marozzi",
"Giovanni",
""
]
] | We discuss several issues related to a recent proposal for defining classical spatial averages to be used in the so-called cosmological backreaction problem. In the large averaging-volume limit all gauge dependence disappears and different averages can be univocally characterized by the observers associated with different scalar fields. The relation between such averaging procedure and the standard one is emphasized and a gauge invariant way to select different observers is presented. For finite averaging volumes we show that, within our proposal, a residual gauge dependence is left, but is suppressed by several effects. |
2112.05728 | Michele Mancarella | Michele Mancarella, Edwin Genoud-Prachex, Michele Maggiore | Cosmology and modified gravitational wave propagation from binary black
hole population models | 15+6 pages, 7 figures, code $\tt{MGCosmoPop}$ available at
\url{https://github.com/CosmoStatGW/MGCosmoPop}. v2: minor changes, matches
version to appear on PRD | null | 10.1103/PhysRevD.105.064030 | null | gr-qc astro-ph.CO astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | A joint hierarchical Bayesian analysis of the binary black hole (BBH) mass
function, merger rate evolution and cosmological parameters can be used to
extract information on both the cosmological and population parameters. We
extend this technique to include the effect of modified gravitational wave (GW)
propagation. We discuss the constraints on the parameter $\Xi_0$ that describes
this phenomenon (with $\Xi_0=1$ in General Relativity, GR) using the data from
the GWTC-3 catalog. We find the constraints $\Xi_0 = 1.2^{+0.7}_{-0.7}$ with a
flat prior on $\Xi_0$, and $\Xi_0 = 1.0^{+0.4}_{-0.8}$ with a prior uniform in
$\log\Xi_0$ ($68\%$ C.L., maximum posterior and HDI), which only rely on the
presence of a feature in the BBH mass distribution around $\sim 30-45
M_{\odot}$, and are robust to whether or not the event GW190521 is considered
an outlier of the population. We then study in more detail the effects of
modified GW propagation on population and cosmological analyses for LIGO/Virgo
at design sensitivity. For a given data-taking period, the relative error
$\Delta\Xi_0/\Xi_0$ has a significant dependence on the fiducial value of
$\Xi_0$, since the latter has a strong influence on the detection rate. For
five years of data, the accuracy ranges from $\sim 10\%$ on $\Xi_0$ when
$\Xi_0=1$ to $\Delta\Xi_0/\Xi_0\sim 20\%$ for $\Xi_0=1.8$ - a large deviation
from GR, still consistent with current limits and predicted by viable
cosmological models. For the Hubble parameter, we forecast an accuracy of
$\Delta H_0/H_0 \sim 20\%$, and an accuracy on $H(z)$ of $\sim7\%$ at a pivot
redshift $z_*\sim 0.8$. We finally show that, if Nature is described by a
modified gravity theory with a large deviation from the GR value $\Xi_0=1$,
such as $\Xi_0=1.8$, analysing the data assuming GR produces a significant bias
in the inferred values of the mass scales, Hubble constant, and BBH merger
rate.
| [
{
"created": "Fri, 10 Dec 2021 18:32:22 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Mar 2022 22:50:02 GMT",
"version": "v2"
}
] | 2022-04-06 | [
[
"Mancarella",
"Michele",
""
],
[
"Genoud-Prachex",
"Edwin",
""
],
[
"Maggiore",
"Michele",
""
]
] | A joint hierarchical Bayesian analysis of the binary black hole (BBH) mass function, merger rate evolution and cosmological parameters can be used to extract information on both the cosmological and population parameters. We extend this technique to include the effect of modified gravitational wave (GW) propagation. We discuss the constraints on the parameter $\Xi_0$ that describes this phenomenon (with $\Xi_0=1$ in General Relativity, GR) using the data from the GWTC-3 catalog. We find the constraints $\Xi_0 = 1.2^{+0.7}_{-0.7}$ with a flat prior on $\Xi_0$, and $\Xi_0 = 1.0^{+0.4}_{-0.8}$ with a prior uniform in $\log\Xi_0$ ($68\%$ C.L., maximum posterior and HDI), which only rely on the presence of a feature in the BBH mass distribution around $\sim 30-45 M_{\odot}$, and are robust to whether or not the event GW190521 is considered an outlier of the population. We then study in more detail the effects of modified GW propagation on population and cosmological analyses for LIGO/Virgo at design sensitivity. For a given data-taking period, the relative error $\Delta\Xi_0/\Xi_0$ has a significant dependence on the fiducial value of $\Xi_0$, since the latter has a strong influence on the detection rate. For five years of data, the accuracy ranges from $\sim 10\%$ on $\Xi_0$ when $\Xi_0=1$ to $\Delta\Xi_0/\Xi_0\sim 20\%$ for $\Xi_0=1.8$ - a large deviation from GR, still consistent with current limits and predicted by viable cosmological models. For the Hubble parameter, we forecast an accuracy of $\Delta H_0/H_0 \sim 20\%$, and an accuracy on $H(z)$ of $\sim7\%$ at a pivot redshift $z_*\sim 0.8$. We finally show that, if Nature is described by a modified gravity theory with a large deviation from the GR value $\Xi_0=1$, such as $\Xi_0=1.8$, analysing the data assuming GR produces a significant bias in the inferred values of the mass scales, Hubble constant, and BBH merger rate. |
0712.1256 | Muhammad Sharif | M. Sharif and M. Jamil Amir | Teleparallel Energy-Momentum Distribution of Spatially Homogeneous
Rotating Spacetimes | 12 pages, accepted for publication in Int. J. Theor. Phys | Int.J.Theor.Phys.47:1742-1750,2008 | 10.1007/s10773-007-9616-7 | null | gr-qc | null | The energy-momentum distribution of spatially homogeneous rotating spacetimes
in the context of teleparallel theory of gravity is investigated. For this
purpose, we use the teleparallel version of Moller prescription. It is found
that the components of energy-momentum density are finite and well-defined but
are different from General Relativity. However, the energy-momentum density
components become the same in both theories under certain assumptions. We also
analyse these quantities for some special solutions of the spatially
homogeneous rotating spacetimes.
| [
{
"created": "Sat, 8 Dec 2007 03:19:30 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Sharif",
"M.",
""
],
[
"Amir",
"M. Jamil",
""
]
] | The energy-momentum distribution of spatially homogeneous rotating spacetimes in the context of teleparallel theory of gravity is investigated. For this purpose, we use the teleparallel version of Moller prescription. It is found that the components of energy-momentum density are finite and well-defined but are different from General Relativity. However, the energy-momentum density components become the same in both theories under certain assumptions. We also analyse these quantities for some special solutions of the spatially homogeneous rotating spacetimes. |
1806.02899 | Mohamed Lamine Abdelali | M. L. Abdelali, N. Mebarki | Redshift effects implications on revised models of Stephan's quintet | 15 pages, 1 table, 1 figure, uses jcappub.sty | Modern Physics Letters A, 35(01), 1950342 (2020) | 10.1142/S0217732319503425 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent observations of Stephan's Quintet gave new indications on its
formation scenario. Older formation and a role of NCG 7317 should be considered
in revised numerical models of the compact group. Velocities of group members
to recreate are estimated from redshift measurements. Several effects
contribute to observed redshifts and a new effect is predicted to be the result
of the gravitational interaction between photons and constant magnetic fields
creating gravitational waves. The energy carried by these waves is manifested
as redshifts of photons. Cosmological simulations data are used to prove the
significant contribution of our effect. The analysis of synthetic observations
created from those simulations has shown that redshifts differences of
Stephanes Quintet members could be misinterpreted as caused only from Doppler
Effect. The revised models of the group should consider a new method to
recreate the formation scenario based on redshift patterns and not
mis-estimated velocities.
| [
{
"created": "Thu, 7 Jun 2018 20:56:29 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Aug 2018 11:17:55 GMT",
"version": "v2"
}
] | 2020-03-17 | [
[
"Abdelali",
"M. L.",
""
],
[
"Mebarki",
"N.",
""
]
] | Recent observations of Stephan's Quintet gave new indications on its formation scenario. Older formation and a role of NCG 7317 should be considered in revised numerical models of the compact group. Velocities of group members to recreate are estimated from redshift measurements. Several effects contribute to observed redshifts and a new effect is predicted to be the result of the gravitational interaction between photons and constant magnetic fields creating gravitational waves. The energy carried by these waves is manifested as redshifts of photons. Cosmological simulations data are used to prove the significant contribution of our effect. The analysis of synthetic observations created from those simulations has shown that redshifts differences of Stephanes Quintet members could be misinterpreted as caused only from Doppler Effect. The revised models of the group should consider a new method to recreate the formation scenario based on redshift patterns and not mis-estimated velocities. |
2101.10598 | Chinmay Gandevikar | Chinmay N. Gandevikar, Divyesh N. Solanki, Dipanjan Dey | Post-Newtonian properties of EMRI with Power Law Potential | 12 pages, 8 figures | null | 10.1140/epjc/s10052-021-09500-2 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | There are many astrophysical scenarios where extreme mass ratio inspiral
(EMRI) binaries can be surrounded by matter distribution. The distribution of
mass can affect the dynamical properties (e.g. orbital frequency, average
energy radiation rate, etc.) of the EMRI. In this matter distribution, instead
of Kepler-Newton potential, one may consider a more general form of potential
i.e. power law potential. Moreover, due to the power law potential, the
velocity profile of test particles does not fall as much as that predicted by
Kepler-Newton potential and this feature of the velocity profile may be
observationally important. In this study, we have obtained the first
post-Newtonian (1PN) expressions for dynamical quantities and the average
energy radiation rate from the circular orbit EMRI which is surrounded by a
matter distribution. We show that the energy radiation rate and orbital
frequency of EMRI can be significantly different in the presence of power law
potential as compared to that in the Kepler-Newton potential, signatures of
which may be observed in gravitational waves from EMRI.
| [
{
"created": "Tue, 26 Jan 2021 07:15:23 GMT",
"version": "v1"
}
] | 2021-09-01 | [
[
"Gandevikar",
"Chinmay N.",
""
],
[
"Solanki",
"Divyesh N.",
""
],
[
"Dey",
"Dipanjan",
""
]
] | There are many astrophysical scenarios where extreme mass ratio inspiral (EMRI) binaries can be surrounded by matter distribution. The distribution of mass can affect the dynamical properties (e.g. orbital frequency, average energy radiation rate, etc.) of the EMRI. In this matter distribution, instead of Kepler-Newton potential, one may consider a more general form of potential i.e. power law potential. Moreover, due to the power law potential, the velocity profile of test particles does not fall as much as that predicted by Kepler-Newton potential and this feature of the velocity profile may be observationally important. In this study, we have obtained the first post-Newtonian (1PN) expressions for dynamical quantities and the average energy radiation rate from the circular orbit EMRI which is surrounded by a matter distribution. We show that the energy radiation rate and orbital frequency of EMRI can be significantly different in the presence of power law potential as compared to that in the Kepler-Newton potential, signatures of which may be observed in gravitational waves from EMRI. |
1711.01772 | Chun-Yen Lin | Jerzy Lewandowski and Chun-Yen Lin | Quantum Reference Frames via Transition Amplitudes in Timeless Quantum
Gravity | Updated journal version | Phys. Rev. D 98, 026023 (2018) | 10.1103/PhysRevD.98.026023 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose an algorithm of extracting Schr\"odinger theories under all viable
physical time from the Einstein-Hilbert path integral, formulated as the
timeless transition amplitudes $\hat{\mathbb{P}}:\mathbb{K} \to \mathbb{K}^*$
between the boundary states in a kinematic Hilbert space $\mathbb{K}$. Each of
these Schr\"odinger theories refers to a certain set of quantum degrees of
freedom in $\mathbb{K}$ as a background, with their given values specifying
moments of the physical time. Restricted to these specified background values,
the relevant elements of $\hat{\mathbb{P}}$ are transformed by the algorithm
into the unitary propagator of a corresponding reduced phase space
Schr\"odinger theory. The algorithm embodies the fundamental principle of
quantum Cauchy surfaces, such that all the derived Schr\"odinger theories
emerge from one timeless canonical theory defined by $\hat{\mathbb{P}}$ as a
rigging map, via the relational Dirac observables referring to the
corresponding backgrounds. We demonstrate its application to a FRW loop quantum
cosmological model with a massless Klein-Gordon scalar field. Recovering the
famous singularity-free quantum gravitational dynamics with the background of
the scalar field, we also obtain in another reference frame a modified
Klein-Gordon field quantum dynamics with the background of the spatial
(quantum) geometry.
| [
{
"created": "Mon, 6 Nov 2017 08:11:27 GMT",
"version": "v1"
},
{
"created": "Sat, 21 Jul 2018 08:50:30 GMT",
"version": "v2"
}
] | 2018-07-25 | [
[
"Lewandowski",
"Jerzy",
""
],
[
"Lin",
"Chun-Yen",
""
]
] | We propose an algorithm of extracting Schr\"odinger theories under all viable physical time from the Einstein-Hilbert path integral, formulated as the timeless transition amplitudes $\hat{\mathbb{P}}:\mathbb{K} \to \mathbb{K}^*$ between the boundary states in a kinematic Hilbert space $\mathbb{K}$. Each of these Schr\"odinger theories refers to a certain set of quantum degrees of freedom in $\mathbb{K}$ as a background, with their given values specifying moments of the physical time. Restricted to these specified background values, the relevant elements of $\hat{\mathbb{P}}$ are transformed by the algorithm into the unitary propagator of a corresponding reduced phase space Schr\"odinger theory. The algorithm embodies the fundamental principle of quantum Cauchy surfaces, such that all the derived Schr\"odinger theories emerge from one timeless canonical theory defined by $\hat{\mathbb{P}}$ as a rigging map, via the relational Dirac observables referring to the corresponding backgrounds. We demonstrate its application to a FRW loop quantum cosmological model with a massless Klein-Gordon scalar field. Recovering the famous singularity-free quantum gravitational dynamics with the background of the scalar field, we also obtain in another reference frame a modified Klein-Gordon field quantum dynamics with the background of the spatial (quantum) geometry. |
gr-qc/0007008 | Frans Pretorius | Frans Pretorius and Matthew W. Choptuik | Gravitational collapse in 2+1 dimensional AdS spacetime | 31 pages, 20 figures, LaTeX. Replaced with version to be published in
Phys. Rev. D | Phys.Rev. D62 (2000) 124012 | 10.1103/PhysRevD.62.124012 | null | gr-qc hep-th | null | We present results of numerical simulations of the formation of black holes
from the gravitational collapse of a massless, minimally-coupled scalar field
in 2+1 dimensional, axially-symmetric, anti de-Sitter (AdS) spacetime. The
geometry exterior to the event horizon approaches the BTZ solution, showing no
evidence of scalar `hair'. To study the interior structure we implement a
variant of black-hole excision, which we call singularity excision. We find
that interior to the event horizon a strong, spacelike curvature singularity
develops. We study the critical behavior at the threshold of black hole
formation, and find a continuously self-similar solution and corresponding
mass-scaling exponent of approximately 1.2. The critical solution is universal
to within a phase that is related to the angle deficit of the spacetime.
| [
{
"created": "Thu, 6 Jul 2000 03:37:54 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Nov 2000 09:38:20 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Pretorius",
"Frans",
""
],
[
"Choptuik",
"Matthew W.",
""
]
] | We present results of numerical simulations of the formation of black holes from the gravitational collapse of a massless, minimally-coupled scalar field in 2+1 dimensional, axially-symmetric, anti de-Sitter (AdS) spacetime. The geometry exterior to the event horizon approaches the BTZ solution, showing no evidence of scalar `hair'. To study the interior structure we implement a variant of black-hole excision, which we call singularity excision. We find that interior to the event horizon a strong, spacelike curvature singularity develops. We study the critical behavior at the threshold of black hole formation, and find a continuously self-similar solution and corresponding mass-scaling exponent of approximately 1.2. The critical solution is universal to within a phase that is related to the angle deficit of the spacetime. |
1304.4074 | Ryan Behunin | R. O. Behunin, D. A. R. Dalvit, R. S. Decca, and C. C. Speake | Limits on the accuracy of isoelectronic gravity measurements at short
separation due to patch potentials | 5 pages, 5 figures | null | 10.1103/PhysRevD.89.051301 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In force sensing experiments intended to measure non-Newtonian gravitational
signals electrostatic patch potentials can give rise to spurious forces,
torques, and noise. Undesired patch-induced interactions can lead to systematic
effects which limit accuracy, and noise can place lower limits on precision. In
this paper we develop the theory for electrostatic patch effects on
isoelectronic experiments, where their mean effect is nullified by design. We
derive analytical expressions for the patch force and torque power spectrum to
estimate the limitations introduced by patch-induced signals.
| [
{
"created": "Mon, 15 Apr 2013 12:48:57 GMT",
"version": "v1"
}
] | 2015-06-15 | [
[
"Behunin",
"R. O.",
""
],
[
"Dalvit",
"D. A. R.",
""
],
[
"Decca",
"R. S.",
""
],
[
"Speake",
"C. C.",
""
]
] | In force sensing experiments intended to measure non-Newtonian gravitational signals electrostatic patch potentials can give rise to spurious forces, torques, and noise. Undesired patch-induced interactions can lead to systematic effects which limit accuracy, and noise can place lower limits on precision. In this paper we develop the theory for electrostatic patch effects on isoelectronic experiments, where their mean effect is nullified by design. We derive analytical expressions for the patch force and torque power spectrum to estimate the limitations introduced by patch-induced signals. |
2012.03994 | Alejandro Asc\'arate | Alejandro Asc\'arate | The Spacetime Picture in Quantum Gravity | 20 pages, accepted for publication in Class. Quantum Grav | null | 10.1088/1361-6382/abcbde | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | We propose an approach which, by combining insights from Loop Quantum Gravity
(LQG), Topos theory, Non-commutative Geometry \`a la Connes, and spacetime
relationalism, provides fertile ground for the search of an adequate spacetime
picture in Quantum Gravity. With this approach, we obtain a novel way of
deducing the quantization of the possible values for the area of a surface. One
gets the same area values than those from the area operator in standard LQG,
but our approach makes a further prediction: some smaller values and
sub-divisions are also allowed. In addition, the area arises as a
noncommutative distance between two noncommutative points, and thus they should
be interpreted as irreducible string-like objects at the physical level (where
the area interpretation for the noncommutative distance holds).
| [
{
"created": "Mon, 7 Dec 2020 19:07:31 GMT",
"version": "v1"
},
{
"created": "Sun, 28 Feb 2021 16:48:16 GMT",
"version": "v2"
},
{
"created": "Wed, 10 Mar 2021 22:41:54 GMT",
"version": "v3"
}
] | 2021-03-12 | [
[
"Ascárate",
"Alejandro",
""
]
] | We propose an approach which, by combining insights from Loop Quantum Gravity (LQG), Topos theory, Non-commutative Geometry \`a la Connes, and spacetime relationalism, provides fertile ground for the search of an adequate spacetime picture in Quantum Gravity. With this approach, we obtain a novel way of deducing the quantization of the possible values for the area of a surface. One gets the same area values than those from the area operator in standard LQG, but our approach makes a further prediction: some smaller values and sub-divisions are also allowed. In addition, the area arises as a noncommutative distance between two noncommutative points, and thus they should be interpreted as irreducible string-like objects at the physical level (where the area interpretation for the noncommutative distance holds). |
1809.07409 | Robert Brandenberger | Robert Brandenberger, Rodrigo R. Cuzinatto, J\"urg Fr\"ohlich and Ryo
Namba | New Scalar Field Quartessence | 6 pages | null | 10.1088/1475-7516/2019/02/043 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a cosmological scenario involving a scalar field, $\varphi$, that
is a source of Dark Matter as well as of Dark Energy. Besides $\varphi$, the
Lagrangian of the field theory envisaged in our scenario contains a second
field $\chi$, for simplicity assumed to be a scalar, too. For fixed values of
$\chi$, the potential term decays exponentially at large positive values of
$\varphi$. While $\varphi$ is not coupled to Standard Model fields, $\chi$ is
assumed to be coupled to them, and the Green functions of $\chi$ depend on the
cosmological redshift in the expanding universe. We assume that the term in the
Lagrangian coupling $\chi$ to $\varphi$ is such that, at redshifts $z$ larger
than some critical redshift $z_c$, $\varphi$ is trapped near $\varphi=0$, and
oscillations of $\varphi$ about $\varphi=0$ describing massive scalar particles
give rise to Dark Matter. At redshifts below $z_c$, the field $\varphi$ is no
longer trapped near the origin and starts to `roll' towards large field values.
A homogenous component of $\varphi$ emerges that acts as Dark Energy. Within
over-dense regions, such as galaxies and galaxy clusters, the redshifting of
$\chi$ stops, and $\varphi$ therefore remains trapped near $\varphi=0$ as long
as $z_c$ is smaller than the redshift when structures on galactic scales
decouple from the Hubble flow. Thus, at the present time, $\varphi$ describes
both Dark Energy and Dark Matter.
| [
{
"created": "Tue, 18 Sep 2018 12:04:23 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Feb 2019 15:44:23 GMT",
"version": "v2"
}
] | 2019-02-27 | [
[
"Brandenberger",
"Robert",
""
],
[
"Cuzinatto",
"Rodrigo R.",
""
],
[
"Fröhlich",
"Jürg",
""
],
[
"Namba",
"Ryo",
""
]
] | We propose a cosmological scenario involving a scalar field, $\varphi$, that is a source of Dark Matter as well as of Dark Energy. Besides $\varphi$, the Lagrangian of the field theory envisaged in our scenario contains a second field $\chi$, for simplicity assumed to be a scalar, too. For fixed values of $\chi$, the potential term decays exponentially at large positive values of $\varphi$. While $\varphi$ is not coupled to Standard Model fields, $\chi$ is assumed to be coupled to them, and the Green functions of $\chi$ depend on the cosmological redshift in the expanding universe. We assume that the term in the Lagrangian coupling $\chi$ to $\varphi$ is such that, at redshifts $z$ larger than some critical redshift $z_c$, $\varphi$ is trapped near $\varphi=0$, and oscillations of $\varphi$ about $\varphi=0$ describing massive scalar particles give rise to Dark Matter. At redshifts below $z_c$, the field $\varphi$ is no longer trapped near the origin and starts to `roll' towards large field values. A homogenous component of $\varphi$ emerges that acts as Dark Energy. Within over-dense regions, such as galaxies and galaxy clusters, the redshifting of $\chi$ stops, and $\varphi$ therefore remains trapped near $\varphi=0$ as long as $z_c$ is smaller than the redshift when structures on galactic scales decouple from the Hubble flow. Thus, at the present time, $\varphi$ describes both Dark Energy and Dark Matter. |
0912.1517 | Tomislav Prokopec | Jeroen G. Burgers, Christiaan L. M. Mantz, Tomislav Prokopec | The Newtonian Limit of Hermitian Gravity | The published version in Gen. Rel. Grav. 24 pages, no figures | null | 10.1007/s10714-012-1465-x | SPIN-09/46; ITP-UU-09/56 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct the gauge invariant potentials of Hermitian Gravity and derive
the linearized equations of motion they obey. A comparison reveals a striking
similarity to the Bardeen potentials of general relativity. We then consider
the response to a point particle source, and discuss in what sense the
solutions of Hermitian Gravity reduce to the Newtonian potentials. In a rather
intriguing way, the Hermitian Gravity solutions exhibit a generalized
reciprocity symmetry originally proposed by Born in the 1930s. Finally, we
consider the trajectories of massive and massless particles under the influence
of a potential. The theory correctly reproduces the Newtonian limit in three
dimensions and the nonrelativistic acceleration equation. However, it differs
from the light deflection calculated in linearized generalrelativity by 25%.
While the specific complexification of general relativity by extension to
Hermitian spaces performed here does not agree with experiment, it does possess
useful properties for quantization and is well-behaved around singularities.
Another form of complex general relativity may very well agree with
experimental data.
| [
{
"created": "Tue, 8 Dec 2009 15:05:05 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Oct 2012 08:27:51 GMT",
"version": "v2"
}
] | 2012-10-25 | [
[
"Burgers",
"Jeroen G.",
""
],
[
"Mantz",
"Christiaan L. M.",
""
],
[
"Prokopec",
"Tomislav",
""
]
] | We construct the gauge invariant potentials of Hermitian Gravity and derive the linearized equations of motion they obey. A comparison reveals a striking similarity to the Bardeen potentials of general relativity. We then consider the response to a point particle source, and discuss in what sense the solutions of Hermitian Gravity reduce to the Newtonian potentials. In a rather intriguing way, the Hermitian Gravity solutions exhibit a generalized reciprocity symmetry originally proposed by Born in the 1930s. Finally, we consider the trajectories of massive and massless particles under the influence of a potential. The theory correctly reproduces the Newtonian limit in three dimensions and the nonrelativistic acceleration equation. However, it differs from the light deflection calculated in linearized generalrelativity by 25%. While the specific complexification of general relativity by extension to Hermitian spaces performed here does not agree with experiment, it does possess useful properties for quantization and is well-behaved around singularities. Another form of complex general relativity may very well agree with experimental data. |
1602.01492 | Francisco Lobo | Francisco Cabral, Francisco S. N. Lobo | Electrodynamics and spacetime geometry I: Foundations | 21 pages | Found Phys (2017) 47: 208 | 10.1007/s10701-016-0051-6 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore the intimate connection between spacetime geometry and
electrodynamics. This link is already implicit in the constitutive relations
between the field strengths and excitations, which are an essential part of the
axiomatic structure of electromagnetism, clearly formulated via integration
theory and differential forms. We briefly review the foundations of
electromagnetism based on charge and magnetic flux conservation, the Lorentz
force and the constitutive relations which introduce the spacetime metric. We
then proceed with the tensor formulation by assuming local, linear, homogeneous
and isotropic constitutive relations, and explore the physical, observable
consequences of Maxwell's equations in curved spacetime. The field equations,
charge conservation and the Lorentz force are explicitly expressed in general
(pseudo) Riemanian manifolds. The generalized Gauss and Maxwell-Amp\`{e}re
laws, as well as the wave equations, reveal potentially interesting
astrophysical applications. In all cases new electromagnetic couplings and
related phenomena are induced by spacetime curvature. The implications and
possible applications for gravity waves detection are briefly addressed. At the
foundational level, we discuss the possibility of generalizing the vacuum
constitutive relations, by relaxing the fixed conditions of homogeneity and
isotropy, and by assuming that the symmetry properties of the electro-vacuum
follow the spacetime isometries. The implications of this extension are briefly
discussed in the context of the intimate connection between electromagnetism
and the geometry (and causal structure) of spacetime.
| [
{
"created": "Wed, 3 Feb 2016 21:56:46 GMT",
"version": "v1"
}
] | 2017-02-14 | [
[
"Cabral",
"Francisco",
""
],
[
"Lobo",
"Francisco S. N.",
""
]
] | We explore the intimate connection between spacetime geometry and electrodynamics. This link is already implicit in the constitutive relations between the field strengths and excitations, which are an essential part of the axiomatic structure of electromagnetism, clearly formulated via integration theory and differential forms. We briefly review the foundations of electromagnetism based on charge and magnetic flux conservation, the Lorentz force and the constitutive relations which introduce the spacetime metric. We then proceed with the tensor formulation by assuming local, linear, homogeneous and isotropic constitutive relations, and explore the physical, observable consequences of Maxwell's equations in curved spacetime. The field equations, charge conservation and the Lorentz force are explicitly expressed in general (pseudo) Riemanian manifolds. The generalized Gauss and Maxwell-Amp\`{e}re laws, as well as the wave equations, reveal potentially interesting astrophysical applications. In all cases new electromagnetic couplings and related phenomena are induced by spacetime curvature. The implications and possible applications for gravity waves detection are briefly addressed. At the foundational level, we discuss the possibility of generalizing the vacuum constitutive relations, by relaxing the fixed conditions of homogeneity and isotropy, and by assuming that the symmetry properties of the electro-vacuum follow the spacetime isometries. The implications of this extension are briefly discussed in the context of the intimate connection between electromagnetism and the geometry (and causal structure) of spacetime. |
1007.2662 | Richard Woodard | Sohyun Park and R. P. Woodard (University of Florida) | Solving the Effective Field Equations for the Newtonian Potential | 15 pages, uses LaTeX2e | Class.Quant.Grav.27:245008,2010 | 10.1088/0264-9381/27/24/245008 | UFIFT-QG-10-06 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Loop corrections to the gravitational potential are usually inferred from
scattering amplitudes, which seems quite different from how the linearized
Einstein equations are solved with a static, point mass to give the classical
potential. In this study we show how the Schwinger-Keldysh effective field
equations can be used to compute loop corrections to the potential in a way
which parallels the classical treatment. We derive explicit results for the one
loop correction from the graviton self-energy induced by a massless, minimally
coupled scalar.
| [
{
"created": "Thu, 15 Jul 2010 21:30:15 GMT",
"version": "v1"
}
] | 2010-12-06 | [
[
"Park",
"Sohyun",
"",
"University of Florida"
],
[
"Woodard",
"R. P.",
"",
"University of Florida"
]
] | Loop corrections to the gravitational potential are usually inferred from scattering amplitudes, which seems quite different from how the linearized Einstein equations are solved with a static, point mass to give the classical potential. In this study we show how the Schwinger-Keldysh effective field equations can be used to compute loop corrections to the potential in a way which parallels the classical treatment. We derive explicit results for the one loop correction from the graviton self-energy induced by a massless, minimally coupled scalar. |
2305.04947 | Shahar Hod | Shahar Hod | Universal lower bound on orbital periods around central compact objects | 12 pages | The European Physical Journal C (Letter) 83, 655 (2023) | 10.1140/epjc/s10052-023-11844-w | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | It is proved, using the curved line element of a spherically symmetric
charged object in general relativity and the Schwinger discharge mechanism of
quantum field theory, that the orbital periods $T_{\infty}$ of test particles
around central compact objects as measured by flat-space asymptotic observers
are fundamentally bounded from below. The lower bound on orbital periods
becomes universal (independent of the mass $M$ of the central compact object)
in the dimensionless $ME_{\text{c}}\gg1$ regime, in which case it can be
expressed in terms of the electric charge $e$ and the proper mass $m_{e}$ of
the lightest charged particle in nature: $T_{\infty}>{{2\pi
e\hbar}\over{\sqrt{G}c^2 m^2_{e}}}$ (here $E_{\text{c}}=m^2_{e}/e\hbar$ is the
critical electric field for pair production). The explicit dependence of the
bound on the fundamental constants of nature $\{G,c,\hbar\}$ suggests that it
may reflect a fundamental physical property of the elusive quantum theory of
gravity.
| [
{
"created": "Mon, 8 May 2023 18:00:01 GMT",
"version": "v1"
}
] | 2023-09-29 | [
[
"Hod",
"Shahar",
""
]
] | It is proved, using the curved line element of a spherically symmetric charged object in general relativity and the Schwinger discharge mechanism of quantum field theory, that the orbital periods $T_{\infty}$ of test particles around central compact objects as measured by flat-space asymptotic observers are fundamentally bounded from below. The lower bound on orbital periods becomes universal (independent of the mass $M$ of the central compact object) in the dimensionless $ME_{\text{c}}\gg1$ regime, in which case it can be expressed in terms of the electric charge $e$ and the proper mass $m_{e}$ of the lightest charged particle in nature: $T_{\infty}>{{2\pi e\hbar}\over{\sqrt{G}c^2 m^2_{e}}}$ (here $E_{\text{c}}=m^2_{e}/e\hbar$ is the critical electric field for pair production). The explicit dependence of the bound on the fundamental constants of nature $\{G,c,\hbar\}$ suggests that it may reflect a fundamental physical property of the elusive quantum theory of gravity. |
1503.08911 | Antony Speranza | Ted Jacobson and Antony J. Speranza | Variations on an aethereal theme | References added, discussion improved in section IV.C. 13 pages, 2
columns | Phys. Rev. D 92, 044030 (2015) | 10.1103/PhysRevD.92.044030 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a class of Lorentz-violating theories of gravity involving a
timelike unit vector field (the aether) coupled to a metric, two examples being
Einstein-aether theory and Ho\v{r}ava gravity. The action always includes the
Ricci scalar of the metric and the invariants quadratic in covariant
derivatives of the aether, but the theories differ in how the aether is
constructed from other fields, and whether those fields are varied in the
action. Fields that are not varied define background structures breaking
diffeomorphsim invariance, including threadings, folations, and clocks, which
generally produce novel degrees of freedom arising from the violation of what
would otherwise be initial value constraints. The principal aims of this paper
are to survey the nature of the theories that arise, and to understand the
consequences of breaking diffeomorphism invariance in this setting. In a
companion paper [arXiv:1504.03305], we address some of the phenomenology of the
"ponderable aether" case in which the presence of a background clock endows the
aether with a variable internal energy density that behaves in some respects
like dark matter.
| [
{
"created": "Tue, 31 Mar 2015 04:39:24 GMT",
"version": "v1"
},
{
"created": "Sat, 29 Aug 2015 23:02:17 GMT",
"version": "v2"
}
] | 2015-09-01 | [
[
"Jacobson",
"Ted",
""
],
[
"Speranza",
"Antony J.",
""
]
] | We consider a class of Lorentz-violating theories of gravity involving a timelike unit vector field (the aether) coupled to a metric, two examples being Einstein-aether theory and Ho\v{r}ava gravity. The action always includes the Ricci scalar of the metric and the invariants quadratic in covariant derivatives of the aether, but the theories differ in how the aether is constructed from other fields, and whether those fields are varied in the action. Fields that are not varied define background structures breaking diffeomorphsim invariance, including threadings, folations, and clocks, which generally produce novel degrees of freedom arising from the violation of what would otherwise be initial value constraints. The principal aims of this paper are to survey the nature of the theories that arise, and to understand the consequences of breaking diffeomorphism invariance in this setting. In a companion paper [arXiv:1504.03305], we address some of the phenomenology of the "ponderable aether" case in which the presence of a background clock endows the aether with a variable internal energy density that behaves in some respects like dark matter. |
2311.17151 | Ivica Smoli\'c | Ana Bokuli\'c, Edgardo Franzin, Tajron Juri\'c, Ivica Smoli\'c | Lagrangian reverse engineering for regular black holes | 8 pages; ver.2: one sentence added, version accepted for publication
in Physics Letters B | Phys. Lett. B 854 (2024) 138750 | 10.1016/j.physletb.2024.138750 | ZTF-EP-23-08 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Nonlinear extensions of classical Maxwell's electromagnetism are among the
prominent candidates for theories admitting regular black hole solutions. A
quest for such examples has been fruitful, but mostly unsystematic and littered
by the introduction of physically unrealistic Lagrangians. We provide a
procedure which admits the reconstruction of a nonlinear electromagnetic
Lagrangian, consistent with the Euler--Heisenberg Lagrangian in the weak-field
limit, from a given metric representing a regular, magnetically charged black
hole.
| [
{
"created": "Tue, 28 Nov 2023 19:00:01 GMT",
"version": "v1"
},
{
"created": "Wed, 29 May 2024 22:06:47 GMT",
"version": "v2"
}
] | 2024-05-31 | [
[
"Bokulić",
"Ana",
""
],
[
"Franzin",
"Edgardo",
""
],
[
"Jurić",
"Tajron",
""
],
[
"Smolić",
"Ivica",
""
]
] | Nonlinear extensions of classical Maxwell's electromagnetism are among the prominent candidates for theories admitting regular black hole solutions. A quest for such examples has been fruitful, but mostly unsystematic and littered by the introduction of physically unrealistic Lagrangians. We provide a procedure which admits the reconstruction of a nonlinear electromagnetic Lagrangian, consistent with the Euler--Heisenberg Lagrangian in the weak-field limit, from a given metric representing a regular, magnetically charged black hole. |
2207.01295 | Emmanuele Battista Dr. | Emmanuele Battista, Harold C. Steinacker | On the propagation across the big bounce in an open quantum FLRW
cosmology | v2: version accepted for publication in EPJ C; conclusions have been
slightly expanded and new references have been added | null | 10.1140/epjc/s10052-022-10874-0 | UWThPh-2022-10 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The propagation of a scalar field in an open FLRW bounce-type quantum
spacetime is examined, which arises within the framework of the IKKT matrix
theory. In the first part of the paper, we employ general-relativity tools to
study null and timelike geodesics at the classical level. This analysis reveals
that massless and massive non-interacting particles can travel across the big
bounce. We then exploit quantum-field-theory techniques to evaluate the scalar
field propagator. In the late-time regime, we find that it resembles the
standard Feynman propagator of flat Minkowski space, whereas for early times it
governs the propagation across the big bounce and gives rise to a well-defined
correlation between two points on opposite sheets of the spacetime.
| [
{
"created": "Mon, 4 Jul 2022 09:55:20 GMT",
"version": "v1"
},
{
"created": "Sun, 2 Oct 2022 15:55:29 GMT",
"version": "v2"
}
] | 2022-10-11 | [
[
"Battista",
"Emmanuele",
""
],
[
"Steinacker",
"Harold C.",
""
]
] | The propagation of a scalar field in an open FLRW bounce-type quantum spacetime is examined, which arises within the framework of the IKKT matrix theory. In the first part of the paper, we employ general-relativity tools to study null and timelike geodesics at the classical level. This analysis reveals that massless and massive non-interacting particles can travel across the big bounce. We then exploit quantum-field-theory techniques to evaluate the scalar field propagator. In the late-time regime, we find that it resembles the standard Feynman propagator of flat Minkowski space, whereas for early times it governs the propagation across the big bounce and gives rise to a well-defined correlation between two points on opposite sheets of the spacetime. |
2106.06704 | Shao-Wen Wei | Shao-Wen Wei, Yu-Xiao Liu | General thermodynamic geometry approach for rotating Kerr anti-de Sitter
black holes | 13 pages and 6 figures | Phys. Rev. D 104, 084087 (2021) | 10.1103/PhysRevD.104.084087 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Combining with the small-large black hole phase transition, the thermodynamic
geometry has been well applied to study the microstructure for the charged AdS
black hole. In this paper, we extend the geometric approach to the rotating
Kerr-AdS black hole and aim to develop a general approach for the Kerr-AdS
black hole. Treating the entropy and pressure as the fluctuation coordinates,
we construct the Ruppeiner geometry for the Kerr-AdS black hole by making the
use of the Christodoulou-Ruffini-like squared-mass formula, which is quite
different from the charged case. Employing the empirical observation of the
corresponding scalar curvature, we find that, for the near-extremal Kerr-AdS
black hole, the repulsive interaction dominates among its microstructure. While
for far-from-extremal Kerr-AdS black hole, the attractive interaction
dominates. The critical phenomenon is also observed for the scalar curvature.
These results uncover the characteristic microstructure of the Kerr-AdS black
hole. Such general thermodynamic geometry approach is worth generalizing to
other rotating AdS black holes, and more interesting microstructure is expected
to be discovered.
| [
{
"created": "Sat, 12 Jun 2021 07:26:22 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Dec 2021 04:22:46 GMT",
"version": "v2"
}
] | 2021-12-06 | [
[
"Wei",
"Shao-Wen",
""
],
[
"Liu",
"Yu-Xiao",
""
]
] | Combining with the small-large black hole phase transition, the thermodynamic geometry has been well applied to study the microstructure for the charged AdS black hole. In this paper, we extend the geometric approach to the rotating Kerr-AdS black hole and aim to develop a general approach for the Kerr-AdS black hole. Treating the entropy and pressure as the fluctuation coordinates, we construct the Ruppeiner geometry for the Kerr-AdS black hole by making the use of the Christodoulou-Ruffini-like squared-mass formula, which is quite different from the charged case. Employing the empirical observation of the corresponding scalar curvature, we find that, for the near-extremal Kerr-AdS black hole, the repulsive interaction dominates among its microstructure. While for far-from-extremal Kerr-AdS black hole, the attractive interaction dominates. The critical phenomenon is also observed for the scalar curvature. These results uncover the characteristic microstructure of the Kerr-AdS black hole. Such general thermodynamic geometry approach is worth generalizing to other rotating AdS black holes, and more interesting microstructure is expected to be discovered. |
1105.4045 | Hossein Farajollahi | H. Farajollahi, A. Salehi, F. Tayebi, A. Ravanpak | Stability Analysis in Tachyonic Potential Chameleon cosmology | 20 pages, 13 figures | JCAP 05(2011)017 | 10.1088/1475-7516/2011/05/017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study general properties of attractors for tachyonic potential chameleon
scalar-field model which possess cosmological scaling solutions. An analytic
formulation is given to obtain fixed points with a discussion on their
stability. The model predicts a dynamical equation of state parameter with
phantom crossing behavior for an accelerating universe. We constrain the
parameters of the model by best fitting with the recent data-sets from
supernovae and simulated data points for redshift drift experiment generated by
Monte Carlo simulations.
| [
{
"created": "Fri, 20 May 2011 09:17:23 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Jun 2011 04:54:19 GMT",
"version": "v2"
}
] | 2015-05-28 | [
[
"Farajollahi",
"H.",
""
],
[
"Salehi",
"A.",
""
],
[
"Tayebi",
"F.",
""
],
[
"Ravanpak",
"A.",
""
]
] | We study general properties of attractors for tachyonic potential chameleon scalar-field model which possess cosmological scaling solutions. An analytic formulation is given to obtain fixed points with a discussion on their stability. The model predicts a dynamical equation of state parameter with phantom crossing behavior for an accelerating universe. We constrain the parameters of the model by best fitting with the recent data-sets from supernovae and simulated data points for redshift drift experiment generated by Monte Carlo simulations. |
gr-qc/9710007 | Kirill Krasnov | A. Ashtekar, J. Baez, A. Corichi and K. Krasnov | Quantum Geometry and Black Hole Entropy | Revtex, 8 pages, 1 figure | Phys.Rev.Lett. 80 (1998) 904-907 | 10.1103/PhysRevLett.80.904 | CGPG-97/9-3 | gr-qc hep-th | null | A `black hole sector' of non-perturbative canonical quantum gravity is
introduced. The quantum black hole degrees of freedom are shown to be described
by a Chern-Simons field theory on the horizon. It is shown that the entropy of
a large non-rotating black hole is proportional to its horizon area. The
constant of proportionality depends upon the Immirzi parameter, which fixes the
spectrum of the area operator in loop quantum gravity; an appropriate choice of
this parameter gives the Bekenstein-Hawking formula S = A/4*l_p^2. With the
same choice of the Immirzi parameter, this result also holds for black holes
carrying electric or dilatonic charge, which are not necessarily near extremal.
| [
{
"created": "Wed, 1 Oct 1997 20:43:41 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Ashtekar",
"A.",
""
],
[
"Baez",
"J.",
""
],
[
"Corichi",
"A.",
""
],
[
"Krasnov",
"K.",
""
]
] | A `black hole sector' of non-perturbative canonical quantum gravity is introduced. The quantum black hole degrees of freedom are shown to be described by a Chern-Simons field theory on the horizon. It is shown that the entropy of a large non-rotating black hole is proportional to its horizon area. The constant of proportionality depends upon the Immirzi parameter, which fixes the spectrum of the area operator in loop quantum gravity; an appropriate choice of this parameter gives the Bekenstein-Hawking formula S = A/4*l_p^2. With the same choice of the Immirzi parameter, this result also holds for black holes carrying electric or dilatonic charge, which are not necessarily near extremal. |
gr-qc/0308056 | Carlos Augusto Romero Filho | F.Dahia and C.Romero | On the embedding of branes in five-dimensional spaces | 12 pages - REVTEX To appear in Classical and Quantum Gravity | Class.Quant.Grav. 21 (2004) 927-934 | 10.1088/0264-9381/21/4/012 | null | gr-qc hep-th | null | We investigate the embedding of four-dimensional branes in five-dimensional
spaces. We firstly consider the case when the embedding space is a vacuum bulk
whose energy-momentum tensor consists of a Dirac delta function with support in
the brane. We then consider the embedding in the context of
Randall-Sundrum-type models, taking into account $Z_{2}$ symmetry and a
cosmological constant. We employ the Campbell-Magaard theorem to construct the
embeddings and are led to the conclusion that the content of energy-matter of
the brane does not necessarily determine its curvature. Finally, as an
application to illustrate our results, we construct the embedding of Minkowski
spacetime filled with dust.
| [
{
"created": "Tue, 19 Aug 2003 02:08:22 GMT",
"version": "v1"
},
{
"created": "Sat, 20 Dec 2003 13:53:36 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Dahia",
"F.",
""
],
[
"Romero",
"C.",
""
]
] | We investigate the embedding of four-dimensional branes in five-dimensional spaces. We firstly consider the case when the embedding space is a vacuum bulk whose energy-momentum tensor consists of a Dirac delta function with support in the brane. We then consider the embedding in the context of Randall-Sundrum-type models, taking into account $Z_{2}$ symmetry and a cosmological constant. We employ the Campbell-Magaard theorem to construct the embeddings and are led to the conclusion that the content of energy-matter of the brane does not necessarily determine its curvature. Finally, as an application to illustrate our results, we construct the embedding of Minkowski spacetime filled with dust. |
2007.09492 | Valeriy Obukhov | Valeriy Obukhov | Separation of variables in Hamilton-Jacobi equation for a charged test
particle in the Stackel spaces of type (2.0) | 17 pagas, submitted to Symmetry | Symmetry.(2020),12, 8, 2432 | 10.3390/SYM12081289 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Found all equivalence classes for electromagnetic potentials and space-time
metrics of Stackel spaces, provided that the equations of motion of the
classical charged test particles are integrated by the method of complete
separation of variables in the Hamilton- Jacobi equation. Separation is carried
out using the complete sets of reciprocal-commuting integrals of motion of type
(2.0), whereby in a privileged coordinate system the Hamilton- Jacobi equation
turns into a nonparabolic type equation.
| [
{
"created": "Sat, 18 Jul 2020 18:10:22 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Dec 2020 13:14:52 GMT",
"version": "v2"
}
] | 2020-12-14 | [
[
"Obukhov",
"Valeriy",
""
]
] | Found all equivalence classes for electromagnetic potentials and space-time metrics of Stackel spaces, provided that the equations of motion of the classical charged test particles are integrated by the method of complete separation of variables in the Hamilton- Jacobi equation. Separation is carried out using the complete sets of reciprocal-commuting integrals of motion of type (2.0), whereby in a privileged coordinate system the Hamilton- Jacobi equation turns into a nonparabolic type equation. |
gr-qc/0406033 | Sujit Chatterjee | D.Panigrahi, Y.Z.Zhang and S.Chatterjee | Multidimensional inhomogeneous cosmology in scalar tensor theory | 12 pages, 2 figures | Int.J.Mod.Phys. D14 (2005) 1083 | 10.1142/S0218271805007000 | null | gr-qc | null | Exact cosmological solutions are obtained for a five dimensional
inhomogeneous fluid distribution along with a Brans-Dicke type of scalar field.
The set includes varied forms of matter field including $\rho+p=0$, where p is
the 3D isotropic pressure. Depending on the signature of 4-space curvature our
solutions admit of indefinite expansion in the usual 3-space and dimensional
reduction of the fifth dimension. Due to the presence of the scalar field the
case $p=-\rho$ does not yield an exponential expansion of the scale factor,
which strikingly differs from our earlier investigations without scalar
field.The \emph{effective} four dimensional values of entropy and matter are
calculated and possible consequences of entropy and matter generation in the 4D
world as a result of dimensional reduction of the extra space are also
discussed. Encouraging to point out that aside from the well known big bang
singularity our inhomogeneous cosmology is spatially regular everywhere.
Further our model seems to suggest an alternative mechanism pointing to a
smooth pass over from a primordial, inhomogeneous cosmological phase to a 4D
homogeneous one.
| [
{
"created": "Tue, 8 Jun 2004 14:17:24 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Panigrahi",
"D.",
""
],
[
"Zhang",
"Y. Z.",
""
],
[
"Chatterjee",
"S.",
""
]
] | Exact cosmological solutions are obtained for a five dimensional inhomogeneous fluid distribution along with a Brans-Dicke type of scalar field. The set includes varied forms of matter field including $\rho+p=0$, where p is the 3D isotropic pressure. Depending on the signature of 4-space curvature our solutions admit of indefinite expansion in the usual 3-space and dimensional reduction of the fifth dimension. Due to the presence of the scalar field the case $p=-\rho$ does not yield an exponential expansion of the scale factor, which strikingly differs from our earlier investigations without scalar field.The \emph{effective} four dimensional values of entropy and matter are calculated and possible consequences of entropy and matter generation in the 4D world as a result of dimensional reduction of the extra space are also discussed. Encouraging to point out that aside from the well known big bang singularity our inhomogeneous cosmology is spatially regular everywhere. Further our model seems to suggest an alternative mechanism pointing to a smooth pass over from a primordial, inhomogeneous cosmological phase to a 4D homogeneous one. |
1012.4287 | Judy Kupferman | Judy Kupferman | Divergence on the Horizon | 8 pages, 3 figures. Contribution to the proceedings of DICE 2010 | J. Phys.: Conf. Ser. 306 012025, 2011 | 10.1088/1742-6596/306/1/012025 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Black hole entropy has been shown by 't Hooft to diverge at the horizon,
whereas entanglement entropy in general does not. We show that because the
region near the horizon is a thermal state, entropy is linear to energy, and
energy at a barrier is inversely proportional to barrier slope, and diverges at
an infinitely sharp barrier as a result of position/momentum uncertainty. We
show that 't Hooft's divergence at the black hole is also an example of
momentum/position uncertainty, as seen by the fact that the "brick wall" which
corrects it in fact smooths the sharp boundary into a more gradual slope. This
removes a major obstacle to identification of black hole entropy with
entanglement entropy.
| [
{
"created": "Mon, 20 Dec 2010 11:20:09 GMT",
"version": "v1"
},
{
"created": "Sun, 16 Jan 2011 12:06:40 GMT",
"version": "v2"
}
] | 2015-05-20 | [
[
"Kupferman",
"Judy",
""
]
] | Black hole entropy has been shown by 't Hooft to diverge at the horizon, whereas entanglement entropy in general does not. We show that because the region near the horizon is a thermal state, entropy is linear to energy, and energy at a barrier is inversely proportional to barrier slope, and diverges at an infinitely sharp barrier as a result of position/momentum uncertainty. We show that 't Hooft's divergence at the black hole is also an example of momentum/position uncertainty, as seen by the fact that the "brick wall" which corrects it in fact smooths the sharp boundary into a more gradual slope. This removes a major obstacle to identification of black hole entropy with entanglement entropy. |
1012.1481 | Ahmadjon Abdujabbarov | Ozodbek Rahimov | Magnetized Particle Motion Around Black Hole in Braneworld | 10 pages, 1 figure, accepted for publication in Mod. Phys. Lett. A | Mod.Phys.Lett.A26:399-408,2011 | 10.1142/S0217732311034931 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the motion of a magnetized particle orbiting around a black
hole in braneworld placed in asymptotically uniform magnetic field. The
influence of brane parameter on effective potential of the radial motion of
magnetized spinning particle around the braneworld black hole using
Hamilton-Jacobi formalism is studied. It is found that circular orbits for
photons and slowly moving particles may become stable near $r = 3M$. It was
argued that the radii of the innermost stable circular orbits are sensitive on
the change of brane parameter. Similar discussion without Weil parameter has
been considered by de Felice et all in Ref. \refcite{rs99,98}.
| [
{
"created": "Tue, 7 Dec 2010 11:57:11 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Jul 2011 06:03:56 GMT",
"version": "v2"
}
] | 2015-03-17 | [
[
"Rahimov",
"Ozodbek",
""
]
] | We investigate the motion of a magnetized particle orbiting around a black hole in braneworld placed in asymptotically uniform magnetic field. The influence of brane parameter on effective potential of the radial motion of magnetized spinning particle around the braneworld black hole using Hamilton-Jacobi formalism is studied. It is found that circular orbits for photons and slowly moving particles may become stable near $r = 3M$. It was argued that the radii of the innermost stable circular orbits are sensitive on the change of brane parameter. Similar discussion without Weil parameter has been considered by de Felice et all in Ref. \refcite{rs99,98}. |
2309.15528 | Antoni Ramos-Buades | Antoni Ramos-Buades, Alessandra Buonanno and Jonathan Gair | Bayesian inference of binary black holes with inspiral-merger-ringdown
waveforms using two eccentric parameters | null | null | null | null | gr-qc astro-ph.HE astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Orbital eccentricity is a crucial physical effect to unveil the origin of
compact-object binaries detected by ground- and spaced-based gravitational-wave
(GW) observatories. Here, we perform for the first time a Bayesian inference
study of inspiral-merger-ringdown eccentric waveforms for binary black holes
with non-precessing spins using two (instead of one) eccentric parameters:
eccentricity and relativistic anomaly. We employ for our study the multipolar
effective-one-body (EOB) waveform model SEOBNRv4EHM, and use initial conditions
such that the eccentric parameters are specified at an orbit-averaged
frequency. We show that this new parametrization of the initial conditions
leads to a more efficient sampling of the parameter space. We also assess the
impact of the relativistic-anomaly parameter by performing mock-signal
injections, and we show that neglecting such a parameter can lead to
significant biases in several binary parameters. We validate our model with
mock-signal injections based on numerical-relativity waveforms, and we
demonstrate the ability of the model to accurately recover the injected
parameters. Finally, using standard stochastic samplers employed by the
LIGO-Virgo-KAGRA Collaboration, we analyze a set of real GW signals observed by
the LIGO-Virgo detectors during the first and third runs. We do not find clear
evidence of eccentricity in the signals analyzed, more specifically we measure
$e^{\text{GW150914}}_{\text{gw, 10Hz}}= 0.08^{+0.09}_{-0.06}$,
$e^{\text{GW151226}}_{\text{gw, 20Hz}}= {0.04}^{+0.05}_{-0.04} $, and
$e^{\text{GW190521}}_{\text{gw, 5.5Hz}}= 0.15^{+0.12}_{-0.12}$.
| [
{
"created": "Wed, 27 Sep 2023 09:44:32 GMT",
"version": "v1"
}
] | 2023-09-28 | [
[
"Ramos-Buades",
"Antoni",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Gair",
"Jonathan",
""
]
] | Orbital eccentricity is a crucial physical effect to unveil the origin of compact-object binaries detected by ground- and spaced-based gravitational-wave (GW) observatories. Here, we perform for the first time a Bayesian inference study of inspiral-merger-ringdown eccentric waveforms for binary black holes with non-precessing spins using two (instead of one) eccentric parameters: eccentricity and relativistic anomaly. We employ for our study the multipolar effective-one-body (EOB) waveform model SEOBNRv4EHM, and use initial conditions such that the eccentric parameters are specified at an orbit-averaged frequency. We show that this new parametrization of the initial conditions leads to a more efficient sampling of the parameter space. We also assess the impact of the relativistic-anomaly parameter by performing mock-signal injections, and we show that neglecting such a parameter can lead to significant biases in several binary parameters. We validate our model with mock-signal injections based on numerical-relativity waveforms, and we demonstrate the ability of the model to accurately recover the injected parameters. Finally, using standard stochastic samplers employed by the LIGO-Virgo-KAGRA Collaboration, we analyze a set of real GW signals observed by the LIGO-Virgo detectors during the first and third runs. We do not find clear evidence of eccentricity in the signals analyzed, more specifically we measure $e^{\text{GW150914}}_{\text{gw, 10Hz}}= 0.08^{+0.09}_{-0.06}$, $e^{\text{GW151226}}_{\text{gw, 20Hz}}= {0.04}^{+0.05}_{-0.04} $, and $e^{\text{GW190521}}_{\text{gw, 5.5Hz}}= 0.15^{+0.12}_{-0.12}$. |
1503.07476 | Vaibhav Tiwari | Vaibhav Tiwari, Marco Drago, Valery Frolov, Sergey Klimenko, Guenakh
Mitselmakher, Valentin Necula, Giovanni Prodi, Virginia Re, Francesco Salemi,
Gabriele Vedovato, and Igor Yakushin | Regression of Environmental Noise in LIGO Data | null | null | 10.1088/0264-9381/32/16/165014 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We address the problem of noise regression in the output of
gravitational-wave (GW) interferometers, using data from the physical
environmental monitors (PEM). The objective of the regression analysis is to
predict environmental noise in the gravitational-wave channel from the PEM
measurements. One of the most promising regression method is based on the
construction of Wiener-Kolmogorov filters. Using this method, the seismic noise
cancellation from the LIGO GW channel has already been performed. In the
presented approach the Wiener-Kolmogorov method has been extended,
incorporating banks of Wiener filters in the time-frequency domain,
multi-channel analysis and regulation schemes, which greatly enhance the
versatility of the regression analysis. Also we presents the first results on
regression of the bi-coherent noise in the LIGO data.
| [
{
"created": "Wed, 25 Mar 2015 17:54:58 GMT",
"version": "v1"
}
] | 2015-08-26 | [
[
"Tiwari",
"Vaibhav",
""
],
[
"Drago",
"Marco",
""
],
[
"Frolov",
"Valery",
""
],
[
"Klimenko",
"Sergey",
""
],
[
"Mitselmakher",
"Guenakh",
""
],
[
"Necula",
"Valentin",
""
],
[
"Prodi",
"Giovanni",
""
],... | We address the problem of noise regression in the output of gravitational-wave (GW) interferometers, using data from the physical environmental monitors (PEM). The objective of the regression analysis is to predict environmental noise in the gravitational-wave channel from the PEM measurements. One of the most promising regression method is based on the construction of Wiener-Kolmogorov filters. Using this method, the seismic noise cancellation from the LIGO GW channel has already been performed. In the presented approach the Wiener-Kolmogorov method has been extended, incorporating banks of Wiener filters in the time-frequency domain, multi-channel analysis and regulation schemes, which greatly enhance the versatility of the regression analysis. Also we presents the first results on regression of the bi-coherent noise in the LIGO data. |
2304.08455 | Ryan Unger | Christoph Kehle and Ryan Unger | Event horizon gluing and black hole formation in vacuum: the very slowly
rotating case | 27 pages + references. 5 figures | null | null | null | gr-qc math.AP math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we initiate the study of characteristic event horizon gluing
in vacuum. More precisely, we prove that Minkowski space can be glued along a
null hypersurface to any round symmetry sphere in a Schwarzschild black hole
spacetime as a $C^2$ solution of the Einstein vacuum equations. The method of
proof is fundamentally nonperturbative and is closely related to our previous
work in spherical symmetry [KU22] and Christodoulou's short pulse method
[Chr09]. We also make essential use of the perturbative characteristic gluing
results of Aretakis-Czimek-Rodnianski [ACR21a; CR22]. As an immediate corollary
of our methods, we obtain characteristic gluing of Minkowski space to the event
horizon of very slowly rotating Kerr with prescribed mass $M$ and specific
angular momentum $a$. Using our characteristic gluing results, we construct
examples of vacuum gravitational collapse to very slowly rotating Kerr black
holes in finite advanced time with prescribed $M$ and $0\le |a|\ll M$. Our
construction also yields the first example of a spacelike singularity arising
from one-ended, asymptotically flat gravitational collapse in vacuum.
| [
{
"created": "Mon, 17 Apr 2023 17:26:54 GMT",
"version": "v1"
}
] | 2023-04-18 | [
[
"Kehle",
"Christoph",
""
],
[
"Unger",
"Ryan",
""
]
] | In this paper, we initiate the study of characteristic event horizon gluing in vacuum. More precisely, we prove that Minkowski space can be glued along a null hypersurface to any round symmetry sphere in a Schwarzschild black hole spacetime as a $C^2$ solution of the Einstein vacuum equations. The method of proof is fundamentally nonperturbative and is closely related to our previous work in spherical symmetry [KU22] and Christodoulou's short pulse method [Chr09]. We also make essential use of the perturbative characteristic gluing results of Aretakis-Czimek-Rodnianski [ACR21a; CR22]. As an immediate corollary of our methods, we obtain characteristic gluing of Minkowski space to the event horizon of very slowly rotating Kerr with prescribed mass $M$ and specific angular momentum $a$. Using our characteristic gluing results, we construct examples of vacuum gravitational collapse to very slowly rotating Kerr black holes in finite advanced time with prescribed $M$ and $0\le |a|\ll M$. Our construction also yields the first example of a spacelike singularity arising from one-ended, asymptotically flat gravitational collapse in vacuum. |
2010.15039 | S. N Sajadi | S. N. Sajadi, Robert B. Mann, N. Riazi, Saeed Fakhry | Analytically Approximation Solution to Higher Derivative Gravity | 17 pages, 47 figures, Accepted in PRD | null | 10.1103/PhysRevD.102.124026 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain analytical approximate black hole solutions for higher derivative
gravity in the presence of Maxwell electromagnetic source. We construct near
horizon and asymptotic solutions and then use these to obtain an approximate
analytic solution using a continued fraction method to get a complete solution.
We compute the thermodynamic quantities and check the first law and Smarr
formula. Finally, we investigate the null and time-like geodesics of this black
hole.
| [
{
"created": "Wed, 28 Oct 2020 15:22:33 GMT",
"version": "v1"
}
] | 2020-12-16 | [
[
"Sajadi",
"S. N.",
""
],
[
"Mann",
"Robert B.",
""
],
[
"Riazi",
"N.",
""
],
[
"Fakhry",
"Saeed",
""
]
] | We obtain analytical approximate black hole solutions for higher derivative gravity in the presence of Maxwell electromagnetic source. We construct near horizon and asymptotic solutions and then use these to obtain an approximate analytic solution using a continued fraction method to get a complete solution. We compute the thermodynamic quantities and check the first law and Smarr formula. Finally, we investigate the null and time-like geodesics of this black hole. |
gr-qc/0309031 | Llu\'is Bel | Ll. Bel | Time dependence of c and its concomitants | Latex, 11 pages | null | null | null | gr-qc | null | As we showed in a preceding arXiv:gr-qc Einstein equations, conveniently
written, provide the more orthodox and simple description of cosmological
models with a time dependent speed of light $c$. We derive here the concomitant
dependence of the electric permittivity $\epsilon$, the magnetic permeability
$\mu$, the unit of charge $e$, Plank's constant $h$, under the assumption of
the constancy of the fine structure constant $\alpha$, and the masses of
elementary particles $m$. As a consequence of these concomitant dependences on
time they remain constant their ratios $e/m$ as well as their Compton wave
length $\lambda_c$ and their classical radius $r_0$.
| [
{
"created": "Fri, 5 Sep 2003 10:37:49 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Bel",
"Ll.",
""
]
] | As we showed in a preceding arXiv:gr-qc Einstein equations, conveniently written, provide the more orthodox and simple description of cosmological models with a time dependent speed of light $c$. We derive here the concomitant dependence of the electric permittivity $\epsilon$, the magnetic permeability $\mu$, the unit of charge $e$, Plank's constant $h$, under the assumption of the constancy of the fine structure constant $\alpha$, and the masses of elementary particles $m$. As a consequence of these concomitant dependences on time they remain constant their ratios $e/m$ as well as their Compton wave length $\lambda_c$ and their classical radius $r_0$. |
2201.04442 | Misbah Shahzadi | Misbah Shahzadi, Martin Kolo\v{s}, Zden\v{e}k Stuchl\'ik and Yousaf
Habib | Testing alternative theories of gravity by fitting the hot-spot data of
Sgr A* | 23 pages, 2 captioned figures | The European Physical Journal C, 82, (2022) | 10.1140/epjc/s10052-022-10347-4 | null | gr-qc astro-ph.GA astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We are fitting dynamics of electrically neutral hot-spot orbiting around Sgr
A* source in Galactic center, represented by various modifications of the
standard Kerr black hole (BH), to the three flares observed by the GRAVITY
instrument on May 27, July 22, July 28, 2018. We consider stationary,
axisymmetric and asymptotically flat spacetimes describing charged BHs in
general relativity (GR) combined with non-linear electrodynamics, or reflecting
influence of dark matter (DM), or in so called parameterized dirty Kerr
spacetimes. We distinguish the spacetimes having different orbital frequencies
from the standard Kerr BH, and test various BH spacetimes using the hot-spot
data. We show that the orbital frequencies and positions of the hot-spots
orbiting the considered BHs, fit the observed positions and periods of the
flare orbits and give relevant constrains on the parameters of the considered
BH spacetimes and the gravity or other theories behind such modified
spacetimes.
| [
{
"created": "Wed, 12 Jan 2022 12:33:50 GMT",
"version": "v1"
}
] | 2024-03-19 | [
[
"Shahzadi",
"Misbah",
""
],
[
"Kološ",
"Martin",
""
],
[
"Stuchlík",
"Zdeněk",
""
],
[
"Habib",
"Yousaf",
""
]
] | We are fitting dynamics of electrically neutral hot-spot orbiting around Sgr A* source in Galactic center, represented by various modifications of the standard Kerr black hole (BH), to the three flares observed by the GRAVITY instrument on May 27, July 22, July 28, 2018. We consider stationary, axisymmetric and asymptotically flat spacetimes describing charged BHs in general relativity (GR) combined with non-linear electrodynamics, or reflecting influence of dark matter (DM), or in so called parameterized dirty Kerr spacetimes. We distinguish the spacetimes having different orbital frequencies from the standard Kerr BH, and test various BH spacetimes using the hot-spot data. We show that the orbital frequencies and positions of the hot-spots orbiting the considered BHs, fit the observed positions and periods of the flare orbits and give relevant constrains on the parameters of the considered BH spacetimes and the gravity or other theories behind such modified spacetimes. |
0810.5076 | Alexander Kamenshchik | A.A. Andrianov, F. Cannata, A.Y. Kamenshchik, D. Regoli | Phantom without phantom or how the PT symmetry saves us from the Big Rip | revised and enlarged version, to be published in Int. J. Mod. Phys.
D, the title is changed | International Journal of Modern Physics D 19, 97-111 (2010) | 10.1142/S0218271810016269 | null | gr-qc astro-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the PT symmetric flat Friedmann model of two scalar fields with
positive kinetic terms. While the potential of one ("normal") field is taken
real, that of the other field is complex. We study a complex classical solution
of the system of the two Klein-Gordon equations together with the Friedmann
equation. The solution for the normal field is real while the solution for the
second field is purely imaginary, realizing classically the "phantom" behavior.
The energy density and pressure are real and the corresponding geometry is
well-defined. The Lagrangian for the linear perturbations has the correct
potential signs for both the fields, so that the problem of stability does not
arise. The background dynamics is determined by an effective action including
two real fields one normal and one "phantom". Remarkably, the phantom phase in
the cosmological evolution is transient and the Big Rip never occurs. Our model
is contrasted to well-known quintom models, which also include one normal and
one phantom fields.
| [
{
"created": "Tue, 28 Oct 2008 16:39:25 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Nov 2009 16:09:17 GMT",
"version": "v2"
}
] | 2010-02-11 | [
[
"Andrianov",
"A. A.",
""
],
[
"Cannata",
"F.",
""
],
[
"Kamenshchik",
"A. Y.",
""
],
[
"Regoli",
"D.",
""
]
] | We consider the PT symmetric flat Friedmann model of two scalar fields with positive kinetic terms. While the potential of one ("normal") field is taken real, that of the other field is complex. We study a complex classical solution of the system of the two Klein-Gordon equations together with the Friedmann equation. The solution for the normal field is real while the solution for the second field is purely imaginary, realizing classically the "phantom" behavior. The energy density and pressure are real and the corresponding geometry is well-defined. The Lagrangian for the linear perturbations has the correct potential signs for both the fields, so that the problem of stability does not arise. The background dynamics is determined by an effective action including two real fields one normal and one "phantom". Remarkably, the phantom phase in the cosmological evolution is transient and the Big Rip never occurs. Our model is contrasted to well-known quintom models, which also include one normal and one phantom fields. |
1908.10075 | Keisuke Nakashi | Keisuke Nakashi and Takahisa Igata | Effect of a second compact object on stable circular orbits | 11 pages, 7 figures, v2: matches published version in PRD | Phys. Rev. D 100, 104006 (2019) | 10.1103/PhysRevD.100.104006 | RUP-19-24 | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate how stable circular orbits around a main compact object appear
depending on the presence of a second one by using the Majumudar--Papapetrou
dihole spacetime, which consists of the two extremal Reissner--Nordstr\" om
black holes with different masses. While the parameter range of the separation
of the two objects is divided due to the appearance of stable circular orbits,
this division depends on its mass ratio. We show that the mass ratio range
separates into four parts, and we find three critical values as the boundaries.
| [
{
"created": "Tue, 27 Aug 2019 08:25:17 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Nov 2019 05:53:56 GMT",
"version": "v2"
}
] | 2019-11-07 | [
[
"Nakashi",
"Keisuke",
""
],
[
"Igata",
"Takahisa",
""
]
] | We investigate how stable circular orbits around a main compact object appear depending on the presence of a second one by using the Majumudar--Papapetrou dihole spacetime, which consists of the two extremal Reissner--Nordstr\" om black holes with different masses. While the parameter range of the separation of the two objects is divided due to the appearance of stable circular orbits, this division depends on its mass ratio. We show that the mass ratio range separates into four parts, and we find three critical values as the boundaries. |
1005.1460 | H. Kleinert | H. Kleinert | New Gauge Symmetry in Gravity and the Evanescent Role of Torsion | Improved version, 5 pages and 5 figures | Electron.J.Theor.Phys.24:287,2010 | 10.1142/9789814335614_0016 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | If the Einstein-Hilbert action ${\cal L}_{\rm EH}\propto R$ is re-expressed
in Riemann-Cartan spacetime using the gauge fields of translations, the
vierbein field $h^\alpha{}_\mu$, and the gauge field of local Lorentz
transformations, the spin connection $A_{\mu \alpha}{}^ \beta $, there exists a
new gauge symmetry which permits reshuffling the torsion, partially or totally,
into the Cartan curvature term of the Einstein tensor, and back, via a {\em new
multivalued gauge transformation\/}. Torsion can be chosen at will by an
arbitrary gauge fixing functional. There exist many equivalent ways of
specifing the theory, for instance Einstein's traditional way where ${\cal
L}_{\rm EH}$ is expressed completely in terms of the metric $g_{\mu \nu}=h^
\alpha {}_\mu h_ \alpha {}_ \nu $, and the torsion is zero, or Einstein's
teleparallel formulation, where ${\cal L}_{\rm EH}$ is expressed in terms of
the torsion tensor, or an infinity of intermediate ways. As far as the
gravitational field in the far-zone of a celestial object is concerned, matter
composed of spinning particles can be replaced by matter with only orbital
angular momentum, without changing the long-distance forces, no matter which of
the various new gauge representations is used.
| [
{
"created": "Mon, 10 May 2010 06:37:43 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Jun 2010 17:30:56 GMT",
"version": "v2"
}
] | 2017-08-23 | [
[
"Kleinert",
"H.",
""
]
] | If the Einstein-Hilbert action ${\cal L}_{\rm EH}\propto R$ is re-expressed in Riemann-Cartan spacetime using the gauge fields of translations, the vierbein field $h^\alpha{}_\mu$, and the gauge field of local Lorentz transformations, the spin connection $A_{\mu \alpha}{}^ \beta $, there exists a new gauge symmetry which permits reshuffling the torsion, partially or totally, into the Cartan curvature term of the Einstein tensor, and back, via a {\em new multivalued gauge transformation\/}. Torsion can be chosen at will by an arbitrary gauge fixing functional. There exist many equivalent ways of specifing the theory, for instance Einstein's traditional way where ${\cal L}_{\rm EH}$ is expressed completely in terms of the metric $g_{\mu \nu}=h^ \alpha {}_\mu h_ \alpha {}_ \nu $, and the torsion is zero, or Einstein's teleparallel formulation, where ${\cal L}_{\rm EH}$ is expressed in terms of the torsion tensor, or an infinity of intermediate ways. As far as the gravitational field in the far-zone of a celestial object is concerned, matter composed of spinning particles can be replaced by matter with only orbital angular momentum, without changing the long-distance forces, no matter which of the various new gauge representations is used. |
2202.12037 | Jorge Ovalle | J. Ovalle | Warped vacuum energy by black holes | 5 pages, 5 figures | Eur. Phys. J. C, 82 (2022) 170 | 10.1140/epjc/s10052-022-10094-6 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The belief still persists, at least for an important part of the community,
that in general relativity the cosmological constant $\Lambda$ must remain
immaculate. However, Bianchi identities show that $\Lambda$ could acquire local
properties in the presence of matter, i.e.,
$\Lambda\rightarrow\,\Lambda(x^\mu)$. In this paper we go even further, and we
show that a non-uniform vacuum energy does not even require coexistence with
any additional form of matter-energy, nor of any theory beyond general
relativity, at least for extreme environments, such as the proximity of a black
hole.
| [
{
"created": "Thu, 24 Feb 2022 11:35:39 GMT",
"version": "v1"
}
] | 2022-02-25 | [
[
"Ovalle",
"J.",
""
]
] | The belief still persists, at least for an important part of the community, that in general relativity the cosmological constant $\Lambda$ must remain immaculate. However, Bianchi identities show that $\Lambda$ could acquire local properties in the presence of matter, i.e., $\Lambda\rightarrow\,\Lambda(x^\mu)$. In this paper we go even further, and we show that a non-uniform vacuum energy does not even require coexistence with any additional form of matter-energy, nor of any theory beyond general relativity, at least for extreme environments, such as the proximity of a black hole. |
gr-qc/9406003 | Hisaaki Shinkai | Laurens Gunnarsen, Hisa-aki Shinkai and Kei-ichi Maeda | Finding Principal Null Direction for Numerical Relativists | 10 pages, LaTeX style, WU-AP/38/93. Figures are available (hard
copies) upon requests [shinkai@cfi.waseda.ac.jp (H.Shinkai)] | Class. Quantum Grav. 12 (1995) 133-140 | 10.1088/0264-9381/12/1/011 | null | gr-qc | null | We present a new method for finding principal null directions (PNDs). Because
our method assumes as input the intrinsic metric and extrinsic curvature of a
spacelike hypersurface, it should be particularly useful to numerical
relativists. We illustrate our method by finding the PNDs of the
Kastor-Traschen spacetimes, which contain arbitrarily many $Q=M$ black holes in
a de Sitter back-ground.
| [
{
"created": "Thu, 2 Jun 1994 06:43:56 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Gunnarsen",
"Laurens",
""
],
[
"Shinkai",
"Hisa-aki",
""
],
[
"Maeda",
"Kei-ichi",
""
]
] | We present a new method for finding principal null directions (PNDs). Because our method assumes as input the intrinsic metric and extrinsic curvature of a spacelike hypersurface, it should be particularly useful to numerical relativists. We illustrate our method by finding the PNDs of the Kastor-Traschen spacetimes, which contain arbitrarily many $Q=M$ black holes in a de Sitter back-ground. |
2404.04595 | Antonio Vicente-Becerril | Guillermo A. Mena Marug\'an, Antonio Vicente-Becerril and Jes\'us
Y\'ebana Carrilero | Analytic and Numerical Study of Scalar Perturbations in Loop Quantum
Cosmology | 13 pages, 4 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The possibility that quantum geometry effects may alleviate the apparent
tensions existing at large angular scales in the observations of the Cosmic
Microwave Background explains the increasing interest in considering primordial
perturbations within the framework of Loop Quantum Cosmology. In this
framework, a number of approximations have been suggested to simplify the study
of perturbations and derive analytic expressions for the power spectra. This
study requires a new choice of vacuum state that takes into account the
preinflationary background geometry, choice for which we adopt the so-called
NO-AHD prescription. Here, we apply the aforementioned approximations to the
investigation of scalar perturbations. We discuss two approaches to the
quantization of perturbations in Loop Quantum Cosmology, namely the hybrid and
the dressed metric approaches. We improve previous approximations by including
slow-roll corrections in the inflationary era. Moreover, for the first time in
the literature of the NO-AHD prescription, we compute numerically the
primordial power spectra for the two considered approaches, and show that the
analytic estimations are remarkably accurate for all observable modes. We also
discuss the similarities and differences between the spectra obtained with
those two approaches.
| [
{
"created": "Sat, 6 Apr 2024 11:38:22 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jul 2024 10:03:02 GMT",
"version": "v2"
}
] | 2024-07-26 | [
[
"Marugán",
"Guillermo A. Mena",
""
],
[
"Vicente-Becerril",
"Antonio",
""
],
[
"Carrilero",
"Jesús Yébana",
""
]
] | The possibility that quantum geometry effects may alleviate the apparent tensions existing at large angular scales in the observations of the Cosmic Microwave Background explains the increasing interest in considering primordial perturbations within the framework of Loop Quantum Cosmology. In this framework, a number of approximations have been suggested to simplify the study of perturbations and derive analytic expressions for the power spectra. This study requires a new choice of vacuum state that takes into account the preinflationary background geometry, choice for which we adopt the so-called NO-AHD prescription. Here, we apply the aforementioned approximations to the investigation of scalar perturbations. We discuss two approaches to the quantization of perturbations in Loop Quantum Cosmology, namely the hybrid and the dressed metric approaches. We improve previous approximations by including slow-roll corrections in the inflationary era. Moreover, for the first time in the literature of the NO-AHD prescription, we compute numerically the primordial power spectra for the two considered approaches, and show that the analytic estimations are remarkably accurate for all observable modes. We also discuss the similarities and differences between the spectra obtained with those two approaches. |
2206.08867 | Andrey A. Shoom | Andrey A. Shoom | Faraday effect of light caused by plane gravitational wave | 6 pages, 2 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Gravitational field can cause a rotation of polarisation plane of light. This
phenomenon is known as the gravitational Faraday effect. We study the
gravitational Faraday effect of linearly polarised light propagating in the
gravitational field of a weak plane gravitational wave (GW) with $+$, $\times$,
and elliptical polarisation modes. The corresponding gravitational Faraday
rotation is proportional to the wave amplitude and to the squared distance
traveled by light and it is inversely proportional to the GW's squared
wavelength. The rotation is also maximal if light propagates in the direction
perpendicular to the GW propagation, along directions of its polarisation.
There is no gravitational Faraday rotation when light and the GW propagate in
the same or opposite directions, or it propagates along directions
perpendicular to directions of the GW polarisation. Helicity of elliptically
polarised GW gives higher-order contribution to the gravitational Faraday
rotation.
| [
{
"created": "Fri, 17 Jun 2022 16:12:35 GMT",
"version": "v1"
}
] | 2022-06-20 | [
[
"Shoom",
"Andrey A.",
""
]
] | Gravitational field can cause a rotation of polarisation plane of light. This phenomenon is known as the gravitational Faraday effect. We study the gravitational Faraday effect of linearly polarised light propagating in the gravitational field of a weak plane gravitational wave (GW) with $+$, $\times$, and elliptical polarisation modes. The corresponding gravitational Faraday rotation is proportional to the wave amplitude and to the squared distance traveled by light and it is inversely proportional to the GW's squared wavelength. The rotation is also maximal if light propagates in the direction perpendicular to the GW propagation, along directions of its polarisation. There is no gravitational Faraday rotation when light and the GW propagate in the same or opposite directions, or it propagates along directions perpendicular to directions of the GW polarisation. Helicity of elliptically polarised GW gives higher-order contribution to the gravitational Faraday rotation. |
2008.03918 | Avani Patel | Avani Patel | Modified Gravity Corrections in Fundamental Orbital Frequencies in Kerr
Spacetime | 10 pages, 3 figures, 1 table | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | As a first step towards the calculation of waveform of Extreme Mass Ratio
Inspirals for Modified Gravity theories, we calculate the orbital frequencies
of a Small Compact Object inspiralling into a super massive blackhole for a
Nonlocal gravity model. The small compact object moves along an orbit which can
be approximated to a geodesic of the background spacetime due to large mass
ratio of central blackhole to Small Compact Object. In General Relativity, the
fundamental orbital frequencies $\Omega_r,\;\Omega_{\theta}$ and
$\Omega_{\phi}$ can be calculated by solving geodesic equations of the Kerr
metric. If we formulate any modified gravity theory as a small correction in
General Relativity then the spacetime metric around a rotating blackhole in
that theory can be considered as the Kerr metric with small deformations. This
would allow us to calculate fundamental frequencies of geodetic motion of the
orbiting object perturbatively i.e. as Kerr frequencies plus small shifts in
Kerr frequencies coming from the modified gravity part. Using Action-angle
formalism and canonical perturbation theory I calculate the frequency shifts
with respect to Kerr frequencies of the orbital motion around a rotating
blackhole for RR model of Nonlocal gravity theory.
| [
{
"created": "Mon, 10 Aug 2020 06:40:55 GMT",
"version": "v1"
}
] | 2020-08-11 | [
[
"Patel",
"Avani",
""
]
] | As a first step towards the calculation of waveform of Extreme Mass Ratio Inspirals for Modified Gravity theories, we calculate the orbital frequencies of a Small Compact Object inspiralling into a super massive blackhole for a Nonlocal gravity model. The small compact object moves along an orbit which can be approximated to a geodesic of the background spacetime due to large mass ratio of central blackhole to Small Compact Object. In General Relativity, the fundamental orbital frequencies $\Omega_r,\;\Omega_{\theta}$ and $\Omega_{\phi}$ can be calculated by solving geodesic equations of the Kerr metric. If we formulate any modified gravity theory as a small correction in General Relativity then the spacetime metric around a rotating blackhole in that theory can be considered as the Kerr metric with small deformations. This would allow us to calculate fundamental frequencies of geodetic motion of the orbiting object perturbatively i.e. as Kerr frequencies plus small shifts in Kerr frequencies coming from the modified gravity part. Using Action-angle formalism and canonical perturbation theory I calculate the frequency shifts with respect to Kerr frequencies of the orbital motion around a rotating blackhole for RR model of Nonlocal gravity theory. |
gr-qc/9405050 | null | George E.A. Matsas | Do Inertial Electric Charges Radiate with Respect to Uniformly
Accelerated Observers? | 6 pages (REVTEX 3.0), IFT-P017/94 | Gen.Rel.Grav.26:1165-1169,1994 | 10.1007/BF02108941 | null | gr-qc | null | We revisit the long standing problem of analyzing an inertial electric charge
from the point of view of uniformly accelerated observers in the context of
semi-classical gravity. We choose a suitable set of accelerated observers with
respect to which there is no photon emission coming from the inertial charge.
We discuss this result against previous claims [F. Rohrlich, Ann. Phys. (N.Y.)
vol: 22, 169 (1963)]. (This Essay was awarded a Honorable Mention for 1994 by
the Gravity Research Foundation.)
| [
{
"created": "Mon, 23 May 1994 15:01:00 GMT",
"version": "v1"
}
] | 2010-11-01 | [
[
"Matsas",
"George E. A.",
""
]
] | We revisit the long standing problem of analyzing an inertial electric charge from the point of view of uniformly accelerated observers in the context of semi-classical gravity. We choose a suitable set of accelerated observers with respect to which there is no photon emission coming from the inertial charge. We discuss this result against previous claims [F. Rohrlich, Ann. Phys. (N.Y.) vol: 22, 169 (1963)]. (This Essay was awarded a Honorable Mention for 1994 by the Gravity Research Foundation.) |
1408.2226 | Alexander Silenko | Alexander J. Silenko | Quantum-mechanical description of Lense-Thirring effect for relativistic
scalar particles | 9 pages. arXiv admin note: substantial text overlap with
arXiv:1305.6378 | Physics of Particles and Nuclei Letters 10 (2013) 637 | 10.1134/S1547477113070157 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Exact expression for the Foldy-Wouthuysen Hamiltonian of scalar particles is
used for a quantum-mechanical description of the relativistic Lense-Thirring
effect. The exact evolution of the angular momentum operator in the Kerr field
approximated by a spatially isotropic metric is found. The quantum-mechanical
description of the full Lense-Thirring effect based on the Laplace-Runge-Lenz
vector is given in the nonrelativistic and weak-field approximation.
Relativistic quantum-mechanical equations for the velocity and acceleration
operators are obtained. The equation for the acceleration defines the
Coriolis-like and centrifugal-like accelerations and presents the
quantum-mechanical description of the frame-dragging effect.
| [
{
"created": "Sun, 10 Aug 2014 13:20:22 GMT",
"version": "v1"
}
] | 2014-08-12 | [
[
"Silenko",
"Alexander J.",
""
]
] | Exact expression for the Foldy-Wouthuysen Hamiltonian of scalar particles is used for a quantum-mechanical description of the relativistic Lense-Thirring effect. The exact evolution of the angular momentum operator in the Kerr field approximated by a spatially isotropic metric is found. The quantum-mechanical description of the full Lense-Thirring effect based on the Laplace-Runge-Lenz vector is given in the nonrelativistic and weak-field approximation. Relativistic quantum-mechanical equations for the velocity and acceleration operators are obtained. The equation for the acceleration defines the Coriolis-like and centrifugal-like accelerations and presents the quantum-mechanical description of the frame-dragging effect. |
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