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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/0608108 | Piotr T. Chru\'sciel | Yvonne Choquet-Bruhat, Piotr T. Chrusciel, Julien Loizelet | Global solutions of the Einstein-Maxwell equations in higher dimensions | minor corrections | Class.Quant.Grav. 23 (2006) 7383-7394 | 10.1088/0264-9381/23/24/011 | AEI-2006-065 | gr-qc | null | We consider the Einstein-Maxwell equations in space-dimension $n$. We point
out that the Lindblad-Rodnianski stability proof applies to those equations
whatever the space-dimension $n\ge 3$. In even space-time dimension $n+1\ge 6$
we use the standard conformal method on a Minkowski background to give a simple
proof that the maximal globally hyperbolic development of initial data sets
which are sufficiently close to the data for Minkowski space-time and which are
Schwarzschildian outside of a compact set lead to geodesically complete
space-times, with a complete Scri, with smooth conformal structure, and with
the gravitational field approaching the Minkowski metric along null directions
at least as fast as $r^{-(n-1)/2}$.
| [
{
"created": "Thu, 24 Aug 2006 08:15:06 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Nov 2006 07:25:18 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Choquet-Bruhat",
"Yvonne",
""
],
[
"Chrusciel",
"Piotr T.",
""
],
[
"Loizelet",
"Julien",
""
]
] | We consider the Einstein-Maxwell equations in space-dimension $n$. We point out that the Lindblad-Rodnianski stability proof applies to those equations whatever the space-dimension $n\ge 3$. In even space-time dimension $n+1\ge 6$ we use the standard conformal method on a Minkowski background to give a simple proof that the maximal globally hyperbolic development of initial data sets which are sufficiently close to the data for Minkowski space-time and which are Schwarzschildian outside of a compact set lead to geodesically complete space-times, with a complete Scri, with smooth conformal structure, and with the gravitational field approaching the Minkowski metric along null directions at least as fast as $r^{-(n-1)/2}$. |
1307.1145 | Helvi Witek | Helvi Witek | Black hole dynamics in generic spacetimes | PhD thesis, 191pp | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The dynamics of black hole spacetimes play a crucial role in astrophysics,
high energy physics and fundamental physics. In this thesis I have investigated
the dynamics of black holes in generic spacetimes by extending established
numerical relativity methods to higher dimensional or non-asymptotically flat
spacetimes. Additionally, I have explored BH spacetimes perturbed my massive
scalar fields. By developing and further improving NR techniques I have been
able to push our knowledge to new grounds.
| [
{
"created": "Wed, 3 Jul 2013 20:16:52 GMT",
"version": "v1"
}
] | 2013-07-05 | [
[
"Witek",
"Helvi",
""
]
] | The dynamics of black hole spacetimes play a crucial role in astrophysics, high energy physics and fundamental physics. In this thesis I have investigated the dynamics of black holes in generic spacetimes by extending established numerical relativity methods to higher dimensional or non-asymptotically flat spacetimes. Additionally, I have explored BH spacetimes perturbed my massive scalar fields. By developing and further improving NR techniques I have been able to push our knowledge to new grounds. |
gr-qc/0504076 | Achim Kempf | S. Bachmann, A. Kempf | The Transplanckian Question and the Casimir Effect | 26 pages, LaTeX, 3 figures | null | null | null | gr-qc | null | It is known that, through inflation, Planck scale phenomena should have left
an imprint in the cosmic microwave background. The magnitude of this imprint is
expected to be suppressed by a factor $\sigma^n$ where $\sigma\approx 10^{-5}$
is the ratio of the Planck length to the Hubble length during inflation. While
there is no consensus about the value of $n$, it is generally thought that $n$
will determine whether the imprint is observable. Here, we suggest that the
magnitude of the imprint may not be suppressed by any power of $\sigma$ and
that, instead, $\sigma$ may merely quantify the amount of fine tuning required
to achieve an imprint of order one. To this end, we show that the UV/IR scale
separation, $\sigma$, in the analogous case of the Casimir effect plays exactly
this role.
| [
{
"created": "Mon, 18 Apr 2005 08:34:36 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Bachmann",
"S.",
""
],
[
"Kempf",
"A.",
""
]
] | It is known that, through inflation, Planck scale phenomena should have left an imprint in the cosmic microwave background. The magnitude of this imprint is expected to be suppressed by a factor $\sigma^n$ where $\sigma\approx 10^{-5}$ is the ratio of the Planck length to the Hubble length during inflation. While there is no consensus about the value of $n$, it is generally thought that $n$ will determine whether the imprint is observable. Here, we suggest that the magnitude of the imprint may not be suppressed by any power of $\sigma$ and that, instead, $\sigma$ may merely quantify the amount of fine tuning required to achieve an imprint of order one. To this end, we show that the UV/IR scale separation, $\sigma$, in the analogous case of the Casimir effect plays exactly this role. |
gr-qc/9909043 | Marsha Weaver | Marsha Weaver | Dynamics of magnetic Bianchi VI_0 cosmologies | 14 pages, 1 figure. Final version | Class.Quant.Grav. 17 (2000) 421-434 | 10.1088/0264-9381/17/2/311 | AEI-1999-57 | gr-qc | null | Methods of dynamical systems analysis are used to show rigorously that the
presence of a magnetic field orthogonal to the two commuting Killing vector
fields in any spatially homogeneous Bianchi type VI_0 vacuum solution to
Einstein's equation changes the evolution toward the singularity from
convergent to oscillatory. In particular, it is shown that the alpha-limit set
(for time direction that puts the singularity in the past) of any of these
magnetic solutions contains at least two sequential Kasner points of the BKL
sequence and the orbit of the transition solution between them. One of the
Kasner points in the alpha-limit set is non-flat, which leads to the result
that each of these magnetic solutions has a curvature singularity.
| [
{
"created": "Tue, 14 Sep 1999 18:01:49 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Nov 1999 23:01:11 GMT",
"version": "v2"
},
{
"created": "Thu, 11 Nov 1999 00:05:55 GMT",
"version": "v3"
},
{
"created": "Thu, 23 Dec 1999 17:41:55 GMT",
"version": "v4"
}
] | 2009-10-31 | [
[
"Weaver",
"Marsha",
""
]
] | Methods of dynamical systems analysis are used to show rigorously that the presence of a magnetic field orthogonal to the two commuting Killing vector fields in any spatially homogeneous Bianchi type VI_0 vacuum solution to Einstein's equation changes the evolution toward the singularity from convergent to oscillatory. In particular, it is shown that the alpha-limit set (for time direction that puts the singularity in the past) of any of these magnetic solutions contains at least two sequential Kasner points of the BKL sequence and the orbit of the transition solution between them. One of the Kasner points in the alpha-limit set is non-flat, which leads to the result that each of these magnetic solutions has a curvature singularity. |
2304.08141 | Pedro Bessa MSc. | Pedro Bessa | Strong Gravitational Lensing in Horndeski theory | 10 pages, accepted for publication in PRD. Includes small corrections
to the accepted that do not alter the content of the text | null | 10.1103/PhysRevD.108.024062 | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | In this paper we build the general formalism of gravitational lensing in
luminal Horndeski theories, deriving the Jacobi matrix equation and the general
angular diameter distance in these theories through the screen space formalism.
We generalize the focusing and multiple lensing theorems to include Scalar
Tensor theories belonging to the class and derive constraints they must satisfy
to exhibit the same gravitional lensing behavior predicted by General
Relativity. This provides a way to test theories through Strong Lensing
effects, as well as a full theoretical framework for testing lensing in these
theories. We find that for some subclasses, like metric $f(R)$ and unified
$k$-essence, the conditions are satisified in general physical cases, while for
others like Galileon Condensate models, the conditions impose constraints on
the parameter space of the theory.
| [
{
"created": "Mon, 17 Apr 2023 10:46:52 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Jul 2023 08:56:39 GMT",
"version": "v2"
}
] | 2023-08-07 | [
[
"Bessa",
"Pedro",
""
]
] | In this paper we build the general formalism of gravitational lensing in luminal Horndeski theories, deriving the Jacobi matrix equation and the general angular diameter distance in these theories through the screen space formalism. We generalize the focusing and multiple lensing theorems to include Scalar Tensor theories belonging to the class and derive constraints they must satisfy to exhibit the same gravitional lensing behavior predicted by General Relativity. This provides a way to test theories through Strong Lensing effects, as well as a full theoretical framework for testing lensing in these theories. We find that for some subclasses, like metric $f(R)$ and unified $k$-essence, the conditions are satisified in general physical cases, while for others like Galileon Condensate models, the conditions impose constraints on the parameter space of the theory. |
1805.11581 | LIGO Scientific Collaboration and Virgo Collaboration | The LIGO Scientific Collaboration and the Virgo Collaboration: B. P.
Abbott, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, C. Adams, T. Adams,
P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, B. Agarwal, M. Agathos,
K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, B.
Allen, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, A. Ananyeva,
S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K.
Arai, M. C. Araya, J. S. Areeda, M. Ar`ene, N. Arnaud, K. G. Arun, S.
Ascenzi, G. Ashton, M. Ast, S. M. Aston, P. Astone, D. V. Atallah, F. Aubin,
P. Aufmuth, C. Aulbert, K. AultONeal, C. Austin, A. Avila-Alvarez, S. Babak,
P. Bacon, F. Badaracco, M. K. M. Bader, S. Bae, P. T. Baker, F. Baldaccini,
G. Ballardin, S. W. Ballmer, S. Banagiri, J. C. Barayoga, S. E. Barclay, B.
C. Barish, D. Barker, K. Barkett, S. Barnum, F. Barone, B. Barr, L. Barsotti,
M. Barsuglia, D. Barta, J. Bartlett, I. Bartos, R. Bassiri, A. Basti, J. C.
Batch, M. Bawaj, J. C. Bayley, M. Bazzan, B. B'ecsy, C. Beer, M. Bejger, I.
Belahcene, A. S. Bell, D. Beniwal, M. Bensch, B. K. Berger, G. Bergmann, S.
Bernuzzi, J. J. Bero, C. P. L. Berry, D. Bersanetti, A. Bertolini, J.
Betzwieser, R. Bhandare, I. A. Bilenko, S. A. Bilgili, G. Billingsley, C. R.
Billman, J. Birch, R. Birney, O. Birnholtz, S. Biscans, S. Biscoveanu, A.
Bisht, M. Bitossi, M. A. Bizouard, J. K. Blackburn, J. Blackman, C. D. Blair,
D. G. Blair, R. M. Blair, S. Bloemen, O. Bock, N. Bode, M. Boer, Y. Boetzel,
G. Bogaert, A. Bohe, F. Bondu, E. Bonilla, R. Bonnand, P. Booker, B. A. Boom,
C. D. Booth, R. Bork, V. Boschi, S. Bose, K. Bossie, V. Bossilkov, J.
Bosveld, Y. Bouffanais, A. Bozzi, C. Bradaschia, P. R. Brady, A. Bramley, M.
Branchesi, J. E. Brau, T. Briant, F. Brighenti, A. Brillet, M. Brinkmann, V.
Brisson, P. Brockill, A. F. Brooks, D. D. Brown, S. Brunett, C. C. Buchanan,
A. Buikema, T. Bulik, H. J. Bulten, A. Buonanno, D. Buskulic, C. Buy, R. L.
Byer, M. Cabero, L. Cadonati, G. Cagnoli, C. Cahillane, J. Calder'on
Bustillo, T. A. Callister, E. Calloni, J. B. Camp, M. Canepa, P. Canizares,
K. C. Cannon, H. Cao, J. Cao, C. D. Capano, E. Capocasa, F. Carbognani, S.
Caride, M. F. Carney, G. Carullo, J. Casanueva Diaz, C. Casentini, S.
Caudill, M. Cavagli`a, F. Cavalier, R. Cavalieri, G. Cella, C. B. Cepeda, P.
Cerd'a-Dur'an, G. Cerretani, E. Cesarini, O. Chaibi, S. J. Chamberlin, M.
Chan, S. Chao, P. Charlton, E. Chase, E. Chassande-Mottin, D. Chatterjee, K.
Chatziioannou, B. D. Cheeseboro, H. Y. Chen, X. Chen, Y. Chen, H.-P. Cheng,
H. Y. Chia, A. Chincarini, A. Chiummo, T. Chmiel, H. S. Cho, M. Cho, J. H.
Chow, N. Christensen, Q. Chu, A. J. K. Chua, S. Chua, K. W. Chung, S. Chung,
G. Ciani, A. A. Ciobanu, R. Ciolfi, F. Cipriano, C. E. Cirelli, A. Cirone, F.
Clara, J. A. Clark, P. Clearwater, F. Cleva, C. Cocchieri, E. Coccia, P.-F.
Cohadon, D. Cohen, A. Colla, C. G. Collette, C. Collins, L. R. Cominsky, M.
Constancio Jr., L. Conti, S. J. Cooper, P. Corban, T. R. Corbitt, I.
Cordero-Carri'on, K. R. Corley, N. Cornish, A. Corsi, S. Cortese, C. A.
Costa, R. Cotesta, M. W. Coughlin, S. B. Coughlin, J.-P. Coulon, S. T.
Countryman, P. Couvares, P. B. Covas, E. E. Cowan, D. M. Coward, M. J.
Cowart, D. C. Coyne, R. Coyne, J. D. E. Creighton, T. D. Creighton, J. Cripe,
S. G. Crowder, T. J. Cullen, A. Cumming, L. Cunningham, E. Cuoco, T. Dal
Canton, G. D'alya, S. L. Danilishin, S. D'Antonio, K. Danzmann, A. Dasgupta,
C. F. Da Silva Costa, V. Dattilo, I. Dave, M. Davier, D. Davis, E. J. Daw, B.
Day, D. DeBra, M. Deenadayalan, J. Degallaix, M. De Laurentis, S. Del'eglise,
W. Del Pozzo, N. Demos, T. Denker, T. Dent, R. De Pietri, J. Derby, V.
Dergachev, R. De Rosa, C. De Rossi, R. DeSalvo, O. de Varona, S. Dhurandhar,
M. C. D'iaz, T. Dietrich, L. Di Fiore, M. Di Giovanni, T. Di Girolamo, A. Di
Lieto, B. Ding, S. Di Pace, I. Di Palma, F. Di Renzo, A. Dmitriev, Z. Doctor,
V. Dolique, F. Donovan, K. L. Dooley, S. Doravari, I. Dorrington, M. Dovale
'Alvarez, T. P. Downes, M. Drago, C. Dreissigacker, J. C. Driggers, Z. Du, P.
Dupej, S. E. Dwyer, P. J. Easter, T. B. Edo, M. C. Edwards, A. Effler, H.-B.
Eggenstein, P. Ehrens, J. Eichholz, S. S. Eikenberry, M. Eisenmann, R. A.
Eisenstein, R. C. Essick, H. Estelles, D. Estevez, Z. B. Etienne, T. Etzel,
M. Evans, T. M. Evans, V. Fafone, H. Fair, S. Fairhurst, X. Fan, S. Farinon,
B. Farr, W. M. Farr, E. J. Fauchon-Jones, M. Favata, M. Fays, C. Fee, H.
Fehrmann, J. Feicht, M. M. Fejer, F. Feng, A. Fernandez-Galiana, I. Ferrante,
E. C. Ferreira, F. Ferrini, F. Fidecaro, I. Fiori, D. Fiorucci, M. Fishbach,
R. P. Fisher, J. M. Fishner, M. Fitz-Axen, R. Flaminio, M. Fletcher, H. Fong,
J. A. Font, P. W. F. Forsyth, S. S. Forsyth, J.-D. Fournier, S. Frasca, F.
Frasconi, Z. Frei, A. Freise, R. Frey, V. Frey, P. Fritschel, V. V. Frolov,
P. Fulda, M. Fyffe, H. A. Gabbard, B. U. Gadre, S. M. Gaebel, J. R. Gair, L.
Gammaitoni, M. R. Ganija, S. G. Gaonkar, A. Garcia, C. Garc'ia-Quir'os, F.
Garufi, B. Gateley, S. Gaudio, G. Gaur, V. Gayathri, G. Gemme, E. Genin, A.
Gennai, D. George, J. George, L. Gergely, V. Germain, S. Ghonge, Abhirup
Ghosh, Archisman Ghosh, S. Ghosh, B. Giacomazzo, J. A. Giaime, K. D.
Giardina, A. Giazotto, K. Gill, G. Giordano, L. Glover, E. Goetz, R. Goetz,
B. Goncharov, G. Gonz'alez, J. M. Gonzalez Castro, A. Gopakumar, M. L.
Gorodetsky, S. E. Gossan, M. Gosselin, R. Gouaty, A. Grado, C. Graef, M.
Granata, A. Grant, S. Gras, C. Gray, G. Greco, A. C. Green, R. Green, E. M.
Gretarsson, P. Groot, H. Grote, S. Grunewald, P. Gruning, G. M. Guidi, H. K.
Gulati, X. Guo, A. Gupta, M. K. Gupta, K. E. Gushwa, E. K. Gustafson, R.
Gustafson, O. Halim, B. R. Hall, E. D. Hall, E. Z. Hamilton, H. F. Hamilton,
G. Hammond, M. Haney, M. M. Hanke, J. Hanks, C. Hanna, M. D. Hannam, O. A.
Hannuksela, J. Hanson, T. Hardwick, J. Harms, G. M. Harry, I. W. Harry, M. J.
Hart, C.-J. Haster, K. Haughian, J. Healy, A. Heidmann, M. C. Heintze, H.
Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, J. Hennig, A. W.
Heptonstall, F. J. Hernandez, M. Heurs, S. Hild, T. Hinderer, W. C. G. Ho, D.
Hoak, S. Hochheim, D. Hofman, N. A. Holland, K. Holt, D. E. Holz, P. Hopkins,
C. Horst, J. Hough, E. A. Houston, E. J. Howell, A. Hreibi, E. A. Huerta, D.
Huet, B. Hughey, M. Hulko, S. Husa, S. H. Huttner, T. Huynh-Dinh, A. Iess, N.
Indik, C. Ingram, R. Inta, G. Intini, B. S. Irwin, H. N. Isa, J.-M. Isac, M.
Isi, B. R. Iyer, K. Izumi, T. Jacqmin, K. Jani, P. Jaranowski, D. S. Johnson,
W. W. Johnson, D. I. Jones, R. Jones, R. J. G. Jonker, L. Ju, J. Junker, C.
V. Kalaghatgi, V. Kalogera, B. Kamai, S. Kandhasamy, G. Kang, J. B. Kanner,
S. J. Kapadia, S. Karki, K. S. Karvinen, M. Kasprzack, M. Katolik, S.
Katsanevas, E. Katsavounidis, W. Katzman, S. Kaufer, K. Kawabe, N. V.
Keerthana, F. K'ef'elian, D. Keitel, A. J. Kemball, R. Kennedy, J. S. Key, F.
Y. Khalili, B. Khamesra, H. Khan, I. Khan, S. Khan, Z. Khan, E. A. Khazanov,
N. Kijbunchoo, Chunglee Kim, J. C. Kim, K. Kim, W. Kim, W. S. Kim, Y.-M. Kim,
E. J. King, P. J. King, M. Kinley-Hanlon, R. Kirchhoff, J. S. Kissel, L.
Kleybolte, S. Klimenko, T. D. Knowles, P. Koch, S. M. Koehlenbeck, S. Koley,
V. Kondrashov, A. Kontos, M. Korobko, W. Z. Korth, I. Kowalska, D. B. Kozak,
C. Kr''amer, V. Kringel, B. Krishnan, A. Kr'olak, G. Kuehn, P. Kumar, R.
Kumar, S. Kumar, L. Kuo, A. Kutynia, S. Kwang, B. D. Lackey, K. H. Lai, M.
Landry, P. Landry, R. N. Lang, J. Lange, B. Lantz, R. K. Lanza, A.
Lartaux-Vollard, P. D. Lasky, M. Laxen, A. Lazzarini, C. Lazzaro, P. Leaci,
S. Leavey, C. H. Lee, H. K. Lee, H. M. Lee, H. W. Lee, K. Lee, J. Lehmann, A.
Lenon, M. Leonardi, N. Leroy, N. Letendre, Y. Levin, J. Li, T. G. F. Li, X.
Li, S. D. Linker, T. B. Littenberg, J. Liu, X. Liu, R. K. L. Lo, N. A.
Lockerbie, L. T. London, A. Longo, M. Lorenzini, V. Loriette, M. Lormand, G.
Losurdo, J. D. Lough, C. O. Lousto, G. Lovelace, H. L''uck, D. Lumaca, A. P.
Lundgren, R. Lynch, Y. Ma, R. Macas, S. Macfoy, B. Machenschalk, M. MacInnis,
D. M. Macleod, I. Maga\~na Hernandez, F. Maga\~na-Sandoval, L. Maga\~na
Zertuche, R. M. Magee, E. Majorana, I. Maksimovic, N. Man, V. Mandic, V.
Mangano, G. L. Mansell, M. Manske, M. Mantovani, F. Marchesoni, F. Marion, S.
M'arka, Z. M'arka, C. Markakis, A. S. Markosyan, A. Markowitz, E. Maros, A.
Marquina, F. Martelli, L. Martellini, I. W. Martin, R. M. Martin, D. V.
Martynov, K. Mason, E. Massera, A. Masserot, T. J. Massinger, M. Masso-Reid,
S. Mastrogiovanni, A. Matas, F. Matichard, L. Matone, N. Mavalvala, N.
Mazumder, J. J. McCann, R. McCarthy, D. E. McClelland, S. McCormick, L.
McCuller, S. C. McGuire, J. McIver, D. J. McManus, T. McRae, S. T.
McWilliams, D. Meacher, G. D. Meadors, M. Mehmet, J. Meidam, E. Mejuto-Villa,
A. Melatos, G. Mendell, D. Mendoza-Gandara, R. A. Mercer, L. Mereni, E. L.
Merilh, M. Merzougui, S. Meshkov, C. Messenger, C. Messick, R. Metzdorff, P.
M. Meyers, H. Miao, C. Michel, H. Middleton, E. E. Mikhailov, L. Milano, A.
L. Miller, A. Miller, B. B. Miller, J. Miller, M. Millhouse, J. Mills, M. C.
Milovich-Goff, O. Minazzoli, Y. Minenkov, J. Ming, C. Mishra, S. Mitra, V. P.
Mitrofanov, G. Mitselmakher, R. Mittleman, D. Moffa, K. Mogushi, M. Mohan, S.
R. P. Mohapatra, M. Montani, C. J. Moore, D. Moraru, G. Moreno, S. Morisaki,
B. Mours, C. M. Mow-Lowry, G. Mueller, A. W. Muir, Arunava Mukherjee, D.
Mukherjee, S. Mukherjee, N. Mukund, A. Mullavey, J. Munch, E. A. Mu\~niz, M.
Muratore, P. G. Murray, A. Nagar, K. Napier, I. Nardecchia, L. Naticchioni,
R. K. Nayak, J. Neilson, G. Nelemans, T. J. N. Nelson, M. Nery, A. Neunzert,
L. Nevin, J. M. Newport, K. Y. Ng, S. Ng, P. Nguyen, T. T. Nguyen, D.
Nichols, A. B. Nielsen, S. Nissanke, A. Nitz, F. Nocera, D. Nolting, C.
North, L. K. Nuttall, M. Obergaulinger, J. Oberling, B. D. O'Brien, G. D.
O'Dea, G. H. Ogin, J. J. Oh, S. H. Oh, F. Ohme, H. Ohta, M. A. Okada, M.
Oliver, P. Oppermann, Richard J. Oram, B. O'Reilly, R. Ormiston, L. F.
Ortega, R. O'Shaughnessy, S. Ossokine, D. J. Ottaway, H. Overmier, B. J.
Owen, A. E. Pace, G. Pagano, J. Page, M. A. Page, A. Pai, S. A. Pai, J. R.
Palamos, O. Palashov, C. Palomba, A. Pal-Singh, Howard Pan, Huang-Wei Pan, B.
Pang, P. T. H. Pang, C. Pankow, F. Pannarale, B. C. Pant, F. Paoletti, A.
Paoli, M. A. Papa, A. Parida, W. Parker, D. Pascucci, A. Pasqualetti, R.
Passaquieti, D. Passuello, M. Patil, B. Patricelli, B. L. Pearlstone, C.
Pedersen, M. Pedraza, R. Pedurand, L. Pekowsky, A. Pele, S. Penn, A. Perego,
C. J. Perez, A. Perreca, L. M. Perri, H. P. Pfeiffer, M. Phelps, K. S.
Phukon, O. J. Piccinni, M. Pichot, F. Piergiovanni, V. Pierro, G. Pillant, L.
Pinard, I. M. Pinto, M. Pirello, M. Pitkin, R. Poggiani, P. Popolizio, E. K.
Porter, L. Possenti, A. Post, J. Powell, J. Prasad, J. W. W. Pratt, G.
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Weinert, A. J. Weinstein, R. Weiss, F. Wellmann, L. Wen, E. K. Wessel, P.
Wessels, J. Westerweck, K. Wette, J. T. Whelan, B. F. Whiting, C. Whittle, D.
Wilken, D. Williams, R. D. Williams, A. R. Williamson, J. L. Willis, B.
Willke, M. H. Wimmer, W. Winkler, C. C. Wipf, H. Wittel, G. Woan, J. Woehler,
J. K. Wofford, W. K. Wong, J. Worden, J. L. Wright, D. S. Wu, D. M. Wysocki,
S. Xiao, W. Yam, H. Yamamoto, C. C. Yancey, L. Yang, M. J. Yap, M. Yazback,
Hang Yu, Haocun Yu, M. Yvert, A. Zadro.zny, M. Zanolin, T. Zelenova, J.-P.
Zendri, M. Zevin, J. Zhang, L. Zhang, M. Zhang, T. Zhang, Y.-H. Zhang, C.
Zhao, M. Zhou, Z. Zhou, S. J. Zhu, X. J. Zhu, A. B. Zimmerman, Y. Zlochower,
M. E. Zucker, J. Zweizig | GW170817: Measurements of Neutron Star Radii and Equation of State | 10 pages, 3 figures; v2 matches published version; data associated
with the figures can be found at https://dcc.ligo.org/LIGO-P1800115/public | Phys. Rev. Lett. 121, 161101 (2018) | 10.1103/PhysRevLett.121.161101 | LIGO-P1800115 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | On 17 August 2017, the LIGO and Virgo observatories made the first direct
detection of gravitational waves from the coalescence of a neutron star binary
system. The detection of this gravitational-wave signal, GW170817, offers a
novel opportunity to directly probe the properties of matter at the extreme
conditions found in the interior of these stars. The initial,
minimal-assumption analysis of the LIGO and Virgo data placed constraints on
the tidal effects of the coalescing bodies, which were then translated to
constraints on neutron star radii. Here, we expand upon previous analyses by
working under the hypothesis that both bodies were neutron stars that are
described by the same equation of state and have spins within the range
observed in Galactic binary neutron stars. Our analysis employs two methods:
the use of equation-of-state-insensitive relations between various macroscopic
properties of the neutron stars and the use of an efficient parametrization of
the defining function $p(\rho)$ of the equation of state itself. From the LIGO
and Virgo data alone and the first method, we measure the two neutron star
radii as $R_1=10.8^{+2.0}_{-1.7}$ km for the heavier star and $R_2=
10.7^{+2.1}_{-1.5}$ km for the lighter star at the 90% credible level. If we
additionally require that the equation of state supports neutron stars with
masses larger than $1.97 \,M_\odot$ as required from electromagnetic
observations and employ the equation-of-state parametrization, we further
constrain $R_1= 11.9^{+1.4}_{-1.4}$ km and $R_2= 11.9^{+1.4}_{-1.4}$ km at the
90% credible level. Finally, we obtain constraints on $p(\rho)$ at supranuclear
densities, with pressure at twice nuclear saturation density measured at
$3.5^{+2.7}_{-1.7}\times 10^{34} \,\mathrm{dyn}/\mathrm{cm}^{2}$ at the 90%
level.
| [
{
"created": "Tue, 29 May 2018 16:56:13 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Oct 2018 17:59:04 GMT",
"version": "v2"
}
] | 2018-10-16 | [
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"M.",
""
],
[
"Tornasi",
"Z.",
""
],
[
"Torres-Forn'e",
"A.",
""
],
[
"Torrie",
"C. I.",
""
],
[
"T''oyr''a",
"D.",
""
],
[
"Travasso",
"F.",
""
],
[
"Traylor",
"G.",
""
],
[
"Trinastic",
"J.",
""
],
[
"Tringali",
"M. C.",
""
],
[
"Trovato",
"A.",
""
],
[
"Trozzo",
"L.",
""
],
[
"Tsang",
"K. W.",
""
],
[
"Tse",
"M.",
""
],
[
"Tso",
"R.",
""
],
[
"Tsuna",
"D.",
""
],
[
"Tsukada",
"L.",
""
],
[
"Tuyenbayev",
"D.",
""
],
[
"Ueno",
"K.",
""
],
[
"Ugolini",
"D.",
""
],
[
"Urban",
"A. L.",
""
],
[
"Usman",
"S. A.",
""
],
[
"Vahlbruch",
"H.",
""
],
[
"Vajente",
"G.",
""
],
[
"Valdes",
"G.",
""
],
[
"van Bakel",
"N.",
""
],
[
"van Beuzekom",
"M.",
""
],
[
"Brand",
"J. F. J. van den",
""
],
[
"Broeck",
"C. Van Den",
""
],
[
"Vander-Hyde",
"D. C.",
""
],
[
"van der Schaaf",
"L.",
""
],
[
"van Heijningen",
"J. V.",
""
],
[
"van Veggel",
"A. A.",
""
],
[
"Vardaro",
"M.",
""
],
[
"Varma",
"V.",
""
],
[
"Vass",
"S.",
""
],
[
"Vas'uth",
"M.",
""
],
[
"Vecchio",
"A.",
""
],
[
"Vedovato",
"G.",
""
],
[
"Veitch",
"J.",
""
],
[
"Veitch",
"P. J.",
""
],
[
"Venkateswara",
"K.",
""
],
[
"Venugopalan",
"G.",
""
],
[
"Verkindt",
"D.",
""
],
[
"Vetrano",
"F.",
""
],
[
"Vicer'e",
"A.",
""
],
[
"Viets",
"A. D.",
""
],
[
"Vinciguerra",
"S.",
""
],
[
"Vine",
"D. J.",
""
],
[
"Vinet",
"J. -Y.",
""
],
[
"Vitale",
"S.",
""
],
[
"Vo",
"T.",
""
],
[
"Vocca",
"H.",
""
],
[
"Vorvick",
"C.",
""
],
[
"Vyatchanin",
"S. P.",
""
],
[
"Wade",
"A. R.",
""
],
[
"Wade",
"L. E.",
""
],
[
"Wade",
"M.",
""
],
[
"Walet",
"R.",
""
],
[
"Walker",
"M.",
""
],
[
"Wallace",
"L.",
""
],
[
"Walsh",
"S.",
""
],
[
"Wang",
"G.",
""
],
[
"Wang",
"H.",
""
],
[
"Wang",
"J. Z.",
""
],
[
"Wang",
"W. H.",
""
],
[
"Wang",
"Y. F.",
""
],
[
"Ward",
"R. L.",
""
],
[
"Warner",
"J.",
""
],
[
"Was",
"M.",
""
],
[
"Watchi",
"J.",
""
],
[
"Weaver",
"B.",
""
],
[
"Wei",
"L. -W.",
""
],
[
"Weinert",
"M.",
""
],
[
"Weinstein",
"A. J.",
""
],
[
"Weiss",
"R.",
""
],
[
"Wellmann",
"F.",
""
],
[
"Wen",
"L.",
""
],
[
"Wessel",
"E. K.",
""
],
[
"Wessels",
"P.",
""
],
[
"Westerweck",
"J.",
""
],
[
"Wette",
"K.",
""
],
[
"Whelan",
"J. T.",
""
],
[
"Whiting",
"B. F.",
""
],
[
"Whittle",
"C.",
""
],
[
"Wilken",
"D.",
""
],
[
"Williams",
"D.",
""
],
[
"Williams",
"R. D.",
""
],
[
"Williamson",
"A. R.",
""
],
[
"Willis",
"J. L.",
""
],
[
"Willke",
"B.",
""
],
[
"Wimmer",
"M. H.",
""
],
[
"Winkler",
"W.",
""
],
[
"Wipf",
"C. C.",
""
],
[
"Wittel",
"H.",
""
],
[
"Woan",
"G.",
""
],
[
"Woehler",
"J.",
""
],
[
"Wofford",
"J. K.",
""
],
[
"Wong",
"W. K.",
""
],
[
"Worden",
"J.",
""
],
[
"Wright",
"J. L.",
""
],
[
"Wu",
"D. S.",
""
],
[
"Wysocki",
"D. M.",
""
],
[
"Xiao",
"S.",
""
],
[
"Yam",
"W.",
""
],
[
"Yamamoto",
"H.",
""
],
[
"Yancey",
"C. C.",
""
],
[
"Yang",
"L.",
""
],
[
"Yap",
"M. J.",
""
],
[
"Yazback",
"M.",
""
],
[
"Yu",
"Hang",
""
],
[
"Yu",
"Haocun",
""
],
[
"Yvert",
"M.",
""
],
[
"zny",
"A. Zadro.",
""
],
[
"Zanolin",
"M.",
""
],
[
"Zelenova",
"T.",
""
],
[
"Zendri",
"J. -P.",
""
],
[
"Zevin",
"M.",
""
],
[
"Zhang",
"J.",
""
],
[
"Zhang",
"L.",
""
],
[
"Zhang",
"M.",
""
],
[
"Zhang",
"T.",
""
],
[
"Zhang",
"Y. -H.",
""
],
[
"Zhao",
"C.",
""
],
[
"Zhou",
"M.",
""
],
[
"Zhou",
"Z.",
""
],
[
"Zhu",
"S. J.",
""
],
[
"Zhu",
"X. J.",
""
],
[
"Zimmerman",
"A. B.",
""
],
[
"Zlochower",
"Y.",
""
],
[
"Zucker",
"M. E.",
""
],
[
"Zweizig",
"J.",
""
]
] | On 17 August 2017, the LIGO and Virgo observatories made the first direct detection of gravitational waves from the coalescence of a neutron star binary system. The detection of this gravitational-wave signal, GW170817, offers a novel opportunity to directly probe the properties of matter at the extreme conditions found in the interior of these stars. The initial, minimal-assumption analysis of the LIGO and Virgo data placed constraints on the tidal effects of the coalescing bodies, which were then translated to constraints on neutron star radii. Here, we expand upon previous analyses by working under the hypothesis that both bodies were neutron stars that are described by the same equation of state and have spins within the range observed in Galactic binary neutron stars. Our analysis employs two methods: the use of equation-of-state-insensitive relations between various macroscopic properties of the neutron stars and the use of an efficient parametrization of the defining function $p(\rho)$ of the equation of state itself. From the LIGO and Virgo data alone and the first method, we measure the two neutron star radii as $R_1=10.8^{+2.0}_{-1.7}$ km for the heavier star and $R_2= 10.7^{+2.1}_{-1.5}$ km for the lighter star at the 90% credible level. If we additionally require that the equation of state supports neutron stars with masses larger than $1.97 \,M_\odot$ as required from electromagnetic observations and employ the equation-of-state parametrization, we further constrain $R_1= 11.9^{+1.4}_{-1.4}$ km and $R_2= 11.9^{+1.4}_{-1.4}$ km at the 90% credible level. Finally, we obtain constraints on $p(\rho)$ at supranuclear densities, with pressure at twice nuclear saturation density measured at $3.5^{+2.7}_{-1.7}\times 10^{34} \,\mathrm{dyn}/\mathrm{cm}^{2}$ at the 90% level. |
1010.5955 | Gao Changjun | Changjun Gao and Anzhong Wang | Ghosts and Stability of Asymptotical Safe Gravity in the Minkowski
Background | 6 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the problems of ghosts and stability in the framework of
asymptotical safe theory of gravity in the Minkowski background. Within one
loop corrections, we obtain explicitly the constraints on the coupling
parameters. Applying them to the coupling constant recently-obtained at the
fixed point, we find that the corresponding theory is both ghost-free and
stable. Our results can be easily generalized to high order corrections.
| [
{
"created": "Thu, 28 Oct 2010 13:10:18 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Dec 2010 00:57:44 GMT",
"version": "v2"
}
] | 2010-12-06 | [
[
"Gao",
"Changjun",
""
],
[
"Wang",
"Anzhong",
""
]
] | We investigate the problems of ghosts and stability in the framework of asymptotical safe theory of gravity in the Minkowski background. Within one loop corrections, we obtain explicitly the constraints on the coupling parameters. Applying them to the coupling constant recently-obtained at the fixed point, we find that the corresponding theory is both ghost-free and stable. Our results can be easily generalized to high order corrections. |
1308.5007 | Fabiola Arevalo | F. Arevalo, P. Cifuentes, S. Lepe and F. Pe\~na | Interacting Ricci-like holographic dark energy | 16 pages, 6 figures, references and comments added, to appear in
Astrophys. Space Sci | null | 10.1007/s10509-014-1946-3 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a flat Friedmann-Lema\^itre-Robertson-Walker background, a scheme of dark
matter-dark energy interaction is studied considering a holographic Ricci-like
model for the dark energy. Without giving a priori some specific model for the
interaction function, we show that this function can experience a change of
sign during the cosmic evolution. The parameters involved in the holographic
model are adjusted with Supernova data and we obtained results compatible with
the observable universe.
| [
{
"created": "Thu, 22 Aug 2013 22:06:56 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Dec 2013 03:56:36 GMT",
"version": "v2"
},
{
"created": "Wed, 2 Jul 2014 20:09:32 GMT",
"version": "v3"
}
] | 2014-07-04 | [
[
"Arevalo",
"F.",
""
],
[
"Cifuentes",
"P.",
""
],
[
"Lepe",
"S.",
""
],
[
"Peña",
"F.",
""
]
] | In a flat Friedmann-Lema\^itre-Robertson-Walker background, a scheme of dark matter-dark energy interaction is studied considering a holographic Ricci-like model for the dark energy. Without giving a priori some specific model for the interaction function, we show that this function can experience a change of sign during the cosmic evolution. The parameters involved in the holographic model are adjusted with Supernova data and we obtained results compatible with the observable universe. |
gr-qc/0010052 | Peter Huebner | Peter Huebner | Numerical Calculation of Conformally Smooth Hyperboloidal Data | 22 pages, 8 figures, revtex4 | Class.Quant.Grav. 18 (2001) 1421-1440 | 10.1088/0264-9381/18/8/302 | AEI-2000-066 | gr-qc | null | This is the third paper in a series describing a numerical implementation of
the conformal Einstein equation. This paper describes a scheme to calculate
(three) dimensional data for the conformal field equations from a set of free
functions. The actual implementation depends on the topology of the spacetime.
We discuss the implementation and exemplary calculations for data leading to
spacetimes with one spherical null infinity (asymptotically Minkowski) and for
data leading to spacetimes with two toroidal null infinities (asymptotically
A3). We also outline the (technical) modifications of the implementation needed
to calculate data for spacetimes with two and more spherical null infinities
(asymptotically Schwarzschild and asymptotically multiple black holes).
| [
{
"created": "Fri, 13 Oct 2000 13:45:50 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Huebner",
"Peter",
""
]
] | This is the third paper in a series describing a numerical implementation of the conformal Einstein equation. This paper describes a scheme to calculate (three) dimensional data for the conformal field equations from a set of free functions. The actual implementation depends on the topology of the spacetime. We discuss the implementation and exemplary calculations for data leading to spacetimes with one spherical null infinity (asymptotically Minkowski) and for data leading to spacetimes with two toroidal null infinities (asymptotically A3). We also outline the (technical) modifications of the implementation needed to calculate data for spacetimes with two and more spherical null infinities (asymptotically Schwarzschild and asymptotically multiple black holes). |
gr-qc/0302031 | Santiago Esteban Perez Bergliaffa | Santiago E. Perez Bergliaffa | Propagation of perturbations in non-linear spin-2 theories | 8 pages, RevTex4, contribution to the Festschrift in honor of
Professor Mario Novello's 60th birthday | null | null | null | gr-qc | null | In this communication I analyze the problem of complete exceptionality of
wave propagation in a class of spin 2 field theories. I show that, under the
imposition of the good weak-field limit, only two Lagrangians are completely
exceptional. These are the linear Fierz Lagrangian, and a Born-Infeld-like
Lagrangian. As a byproduct, I reobtain the result that in a nonlinear theory,
spin 2 particles follow an effective metric that depends on the nonlinearities
of the Lagrangian.
| [
{
"created": "Mon, 10 Feb 2003 13:06:48 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Bergliaffa",
"Santiago E. Perez",
""
]
] | In this communication I analyze the problem of complete exceptionality of wave propagation in a class of spin 2 field theories. I show that, under the imposition of the good weak-field limit, only two Lagrangians are completely exceptional. These are the linear Fierz Lagrangian, and a Born-Infeld-like Lagrangian. As a byproduct, I reobtain the result that in a nonlinear theory, spin 2 particles follow an effective metric that depends on the nonlinearities of the Lagrangian. |
gr-qc/9703003 | Masayuki Tanimoto | Masayuki Tanimoto | On the null surface formalism -- Formulation in three dimensions and
gauge freedom | 6 pages, LaTeX. To appear in Proceedings of the sixth workshop on
General Relativity and Gravitation | null | null | null | gr-qc | null | The null surface formalism of GR in three dimensions is presented, and the
gauge freedom thereof, which is not just diffeomorphism, is discussed briefly.
| [
{
"created": "Fri, 28 Feb 1997 18:54:42 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Tanimoto",
"Masayuki",
""
]
] | The null surface formalism of GR in three dimensions is presented, and the gauge freedom thereof, which is not just diffeomorphism, is discussed briefly. |
gr-qc/0609016 | Ozgur Delice | Ozgur Delice | Local cosmic strings in Brans-Dicke theory with a cosmological constant | 5 pages, Revtex | Phys.Rev.D74:067703,2006 | 10.1103/PhysRevD.74.067703 | null | gr-qc | null | It is known that Vilenkin's phenomenological equation of state for static
straight cosmic strings is inconsistent with Brans-Dicke theory. We will prove
that, in the presence of a cosmological constant, this equation of state is
consistent with Brans-Dicke theory. The general solution of the full nonlinear
field equations, representing the interior of a cosmic string with a
cosmological constant is also presented.
| [
{
"created": "Tue, 5 Sep 2006 21:29:37 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Sep 2006 00:52:50 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Delice",
"Ozgur",
""
]
] | It is known that Vilenkin's phenomenological equation of state for static straight cosmic strings is inconsistent with Brans-Dicke theory. We will prove that, in the presence of a cosmological constant, this equation of state is consistent with Brans-Dicke theory. The general solution of the full nonlinear field equations, representing the interior of a cosmic string with a cosmological constant is also presented. |
gr-qc/0103011 | Roberto Gomez | Roberto Gomez (University of Pittsburgh) | Gravitational waveforms with controlled accuracy | Revised version, published in Phys. Rev. D, RevTeX, 16 pages, 4
figures | Phys.Rev. D64 (2001) 024007 | 10.1103/PhysRevD.64.024007 | null | gr-qc | null | A partially first-order form of the characteristic formulation is introduced
to control the accuracy in the computation of gravitational waveforms produced
by highly distorted single black hole spacetimes. Our approach is to reduce the
system of equations to first-order differential form on the angular
derivatives, while retaining the proven radial and time integration schemes of
the standard characteristic formulation. This results in significantly improved
accuracy over the standard mixed-order approach in the extremely nonlinear
post-merger regime of binary black hole collisions.
| [
{
"created": "Mon, 5 Mar 2001 14:22:54 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Jun 2001 17:26:08 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Gomez",
"Roberto",
"",
"University of Pittsburgh"
]
] | A partially first-order form of the characteristic formulation is introduced to control the accuracy in the computation of gravitational waveforms produced by highly distorted single black hole spacetimes. Our approach is to reduce the system of equations to first-order differential form on the angular derivatives, while retaining the proven radial and time integration schemes of the standard characteristic formulation. This results in significantly improved accuracy over the standard mixed-order approach in the extremely nonlinear post-merger regime of binary black hole collisions. |
1012.4614 | Yury Eroshenko | V.I. Dokuchaev, Yu.N. Eroshenko | Cosmological Horizons as They Are Looked from a Moving Frame | 3 pages, 2 figures, preprint submitted to Theoretical Physics | Theoretical Physics 1, 18 (2016) | 10.22606/tp.2016.11005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the cosmological horizons in the expanding universe from the
point of view of observer moving with respect to CMB frame. The deformation
(non-sphericity) of cosmological horizons is demonstrated. Some principle
consequences are discussed.
| [
{
"created": "Tue, 21 Dec 2010 11:33:10 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Jan 2017 21:14:16 GMT",
"version": "v2"
}
] | 2017-01-20 | [
[
"Dokuchaev",
"V. I.",
""
],
[
"Eroshenko",
"Yu. N.",
""
]
] | We consider the cosmological horizons in the expanding universe from the point of view of observer moving with respect to CMB frame. The deformation (non-sphericity) of cosmological horizons is demonstrated. Some principle consequences are discussed. |
1801.04833 | Natascha Riahi | Natascha Riahi | Wavepacket evolution in unimodular quantum cosmology | 14 pages, 2 figures; contribution to "Cosmology and the Quantum
Vacuum"(Segovia 2017) | Galaxies 2018, 6(1),8 | 10.3390/galaxies6010008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The unimodular theory of gravity admits a canonical quantization of
minisuperspace models without the problem of time. We derive instead a kind of
Schr\"odinger equation. We have found unitarily evolving wave packet solutions
for the special case of a massless scalar field and a spatially flat Friedmann
universe. We show that the longterm behaviour of the expectation values of the
canonical quantities corresponds to the evolution of the classical variables.
The solutions provided in an explicit example can be continued beyond the
singularity at t=0, passing a finite minimal extension of the universe.
| [
{
"created": "Mon, 15 Jan 2018 15:00:29 GMT",
"version": "v1"
}
] | 2018-01-17 | [
[
"Riahi",
"Natascha",
""
]
] | The unimodular theory of gravity admits a canonical quantization of minisuperspace models without the problem of time. We derive instead a kind of Schr\"odinger equation. We have found unitarily evolving wave packet solutions for the special case of a massless scalar field and a spatially flat Friedmann universe. We show that the longterm behaviour of the expectation values of the canonical quantities corresponds to the evolution of the classical variables. The solutions provided in an explicit example can be continued beyond the singularity at t=0, passing a finite minimal extension of the universe. |
2212.13183 | Arnab Dhani | Arnab Dhani, Ssohrab Borhanian, Anuradha Gupta, Bangalore
Sathyaprakash | Cosmography with bright and Love sirens | null | null | null | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | Precision cosmology is crucial to understand the different energy components
in the Universe and their evolution through cosmic time. Gravitational wave
sources are standard sirens that can accurately map out distances in the
Universe. Together with the source redshift information, we can then probe the
expansion history of the Universe. We explore the capabilities of various
gravitational-wave detector networks to constrain different cosmological models
while employing separate waveform models for inspiral and post-merger part of
the gravitational wave signal from equal mass binary neutron stars. We consider
two different avenues to measure the redshift of a gravitational-wave source:
first, we examine an electromagnetic measurement of the redshift via either a
kilonova or a gamma ray burst detection following a binary neutron star merger
(the electromagnetic counterpart method); second, we estimate the redshift from
the gravitational-wave signal itself from the adiabatic tides between the
component stars characterized by the tidal Love number, to provide a second
mass-scale and break the mass-redshift degeneracy (the counterpart-less
method). We find that the electromagnetic counterpart method is better suited
to measure the Hubble constant while the counterpart-less method places more
stringent bounds on other cosmological parameters. In the era of
next-generation gravitational-wave detector networks, both methods achieve
sub-percent measurement of the Hubble constant $H_0$ after one year of
observations. The dark matter energy density parameter $\Omega_{\rm M}$ in the
$\Lambda$CDM model can be measured at percent-level precision using the
counterpart method, whereas the counterpart-less method achieves sub-percent
precision. We, however, do not find the postmerger signal to contribute
significantly to these precision measurements.
| [
{
"created": "Mon, 26 Dec 2022 15:10:04 GMT",
"version": "v1"
}
] | 2022-12-27 | [
[
"Dhani",
"Arnab",
""
],
[
"Borhanian",
"Ssohrab",
""
],
[
"Gupta",
"Anuradha",
""
],
[
"Sathyaprakash",
"Bangalore",
""
]
] | Precision cosmology is crucial to understand the different energy components in the Universe and their evolution through cosmic time. Gravitational wave sources are standard sirens that can accurately map out distances in the Universe. Together with the source redshift information, we can then probe the expansion history of the Universe. We explore the capabilities of various gravitational-wave detector networks to constrain different cosmological models while employing separate waveform models for inspiral and post-merger part of the gravitational wave signal from equal mass binary neutron stars. We consider two different avenues to measure the redshift of a gravitational-wave source: first, we examine an electromagnetic measurement of the redshift via either a kilonova or a gamma ray burst detection following a binary neutron star merger (the electromagnetic counterpart method); second, we estimate the redshift from the gravitational-wave signal itself from the adiabatic tides between the component stars characterized by the tidal Love number, to provide a second mass-scale and break the mass-redshift degeneracy (the counterpart-less method). We find that the electromagnetic counterpart method is better suited to measure the Hubble constant while the counterpart-less method places more stringent bounds on other cosmological parameters. In the era of next-generation gravitational-wave detector networks, both methods achieve sub-percent measurement of the Hubble constant $H_0$ after one year of observations. The dark matter energy density parameter $\Omega_{\rm M}$ in the $\Lambda$CDM model can be measured at percent-level precision using the counterpart method, whereas the counterpart-less method achieves sub-percent precision. We, however, do not find the postmerger signal to contribute significantly to these precision measurements. |
1512.04755 | Pedro Moraes | D. Momeni, P.H.R.S. Moraes, R. Myrzakulov | Generalized second law of thermodynamics in f(R,T) theory of gravity | 6 pages, no figures, accepted for publication in Astrophys. Space Sci | Astrophys.Space Sci. 361 (2016) no.7, 228 | 10.1007/s10509-016-2784-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a study of the generalized second law of thermodynamics in the
scope of the f(R,T) theory of gravity, with R and T representing the Ricci
scalar and trace of the energy-momentum tensor, respectively. From the
energy-momentum tensor equation for the f(R,T) = R + f(T) case, we calculate
the form of the geometric entropy in such a theory. Then, the generalized
second law of thermodynamics is quantified and some relations for its obedience
in f(R,T) gravity are presented. Those relations depend on some cosmological
quantities, as the Hubble and deceleration parameters, and on the form of f(T).
| [
{
"created": "Tue, 15 Dec 2015 12:21:18 GMT",
"version": "v1"
},
{
"created": "Wed, 18 May 2016 12:32:33 GMT",
"version": "v2"
}
] | 2018-10-09 | [
[
"Momeni",
"D.",
""
],
[
"Moraes",
"P. H. R. S.",
""
],
[
"Myrzakulov",
"R.",
""
]
] | We present a study of the generalized second law of thermodynamics in the scope of the f(R,T) theory of gravity, with R and T representing the Ricci scalar and trace of the energy-momentum tensor, respectively. From the energy-momentum tensor equation for the f(R,T) = R + f(T) case, we calculate the form of the geometric entropy in such a theory. Then, the generalized second law of thermodynamics is quantified and some relations for its obedience in f(R,T) gravity are presented. Those relations depend on some cosmological quantities, as the Hubble and deceleration parameters, and on the form of f(T). |
0712.1727 | Sergey Sushkov | Sergey V. Sushkov and Yuan-Zhong Zhang | Scalar wormholes in cosmological setting and their instability | REVTeX4, 11 pages, submitted to PRD | Phys.Rev.D77:024042,2008 | 10.1103/PhysRevD.77.024042 | null | gr-qc | null | We construct exact nonstatic nonhomogeneous spherically symmetric solutions
in the theory of gravity with a scalar field possessing the exponential
potential. The solution of particular interest corresponds to the scalar field
with negative kinetic energy, i.e. a ghost, and represents two asymptotically
homogeneous spatially flat universes connected by a throat. We interpret this
solution as a wormhole in cosmological setting. Both the universes and the
wormhole throat are simultaneously expanding with acceleration. The character
of expansion qualitatively depends on the wormhole's mass $m$. For $m=0$ the
expansion goes exponentially, so that the corresponding spacetime configuration
represents two de Sitter universes joining by the throat. For $m>0$ the
expansion has the power character, so that one has the inflating wormhole
connecting two homogeneous spatially flat universes expanding according to the
power law into the final singularity. The stability analysis of the non-static
wormholes reveals their instability against linear spherically symmetric
perturbations.
| [
{
"created": "Tue, 11 Dec 2007 15:09:45 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Sushkov",
"Sergey V.",
""
],
[
"Zhang",
"Yuan-Zhong",
""
]
] | We construct exact nonstatic nonhomogeneous spherically symmetric solutions in the theory of gravity with a scalar field possessing the exponential potential. The solution of particular interest corresponds to the scalar field with negative kinetic energy, i.e. a ghost, and represents two asymptotically homogeneous spatially flat universes connected by a throat. We interpret this solution as a wormhole in cosmological setting. Both the universes and the wormhole throat are simultaneously expanding with acceleration. The character of expansion qualitatively depends on the wormhole's mass $m$. For $m=0$ the expansion goes exponentially, so that the corresponding spacetime configuration represents two de Sitter universes joining by the throat. For $m>0$ the expansion has the power character, so that one has the inflating wormhole connecting two homogeneous spatially flat universes expanding according to the power law into the final singularity. The stability analysis of the non-static wormholes reveals their instability against linear spherically symmetric perturbations. |
gr-qc/0308086 | Wung-Hong Huang | Wung-Hong Huang | Particle Creation in Kaluza-Klein Cosmology | Latex 11 pages | Phys.Lett.A140:280-284,1989 | 10.1016/0375-9601(89)90619-1 | null | gr-qc hep-th | null | We exactly calculate the particle number $N$ of scalar fields which are
created from an initial vacuum in certain higher-dimensional cosmological
models. The spacetimes in these models are the four-dimensional Chitre-Hartle
or radiation-dominated universe with extra spaces which are static or power-law
contracting. Except for some models in which no particles could be produced,
the distribution of created particles shows a thermal behavior, at least in the
limit of high three-dimensional "momentum" $k$. In some models, $N$ does not
depend on the magnitude of the extra-dimensional "momentum" $k_c$ if $k_c$ is
nonvanishing. A cutoff momentum $k_c$ may emerge in some models, and particles
with $k\le k_c$ could not be produced. We also discuss these results.
| [
{
"created": "Wed, 27 Aug 2003 14:21:43 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Huang",
"Wung-Hong",
""
]
] | We exactly calculate the particle number $N$ of scalar fields which are created from an initial vacuum in certain higher-dimensional cosmological models. The spacetimes in these models are the four-dimensional Chitre-Hartle or radiation-dominated universe with extra spaces which are static or power-law contracting. Except for some models in which no particles could be produced, the distribution of created particles shows a thermal behavior, at least in the limit of high three-dimensional "momentum" $k$. In some models, $N$ does not depend on the magnitude of the extra-dimensional "momentum" $k_c$ if $k_c$ is nonvanishing. A cutoff momentum $k_c$ may emerge in some models, and particles with $k\le k_c$ could not be produced. We also discuss these results. |
2310.17647 | Rajesh Kumar | Annu Jaiswal, Rajesh Kumar, Sudhir Kumar Srivastava, Megandhren
Govender and Shibesh Kumar Jas Pacif | Black hole formation in gravitational collapse and their astrophysical
implications | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we have investigated a novel aspect of black hole (BH)
formation during the collapse of a self-gravitating configuration. The exact
solution of the Einstein field equations is obtained in a model-independent way
by considering a parametrization of the expansion scalar ($\Theta$) in the
background of spherically symmetric space-time geometry governed by the FLRW
metric. Smooth matching of the interior solution with the Schwarzschild
exterior metric across the boundary hypersurface of the star, together with the
condition that the mass function $m(t,r)$ is equal to Schwarzschild mass $M$,
is used to obtain all the physical and geometrical parameters in terms of the
stellar mass. The four known massive stars namely $R136a3$, $Melnick$, $R136c$,
and $R136b$ with their known astrophysical data (mass, radius, and present age)
are used to study the physics of the model both numerically and graphically. We
demonstrate that the formation of the apparent horizon occurs earlier than the
singular state that is, the model of massive stars would inevitably lead to the
formation of a BH as their end state. We have conducted an analysis indicating
that the lifespans of massive stars are closely related to their respective
masses. Our findings demonstrate that more massive stars exhibit considerably
shorter lifespans in comparison to their lighter counterparts. Thus, the
presented model corresponds to the evolutionary stages of astrophysical stellar
objects and theoretically predicts their possible lifespan. We have also shown
that our model satisfies the energy conditions and stability requirements via
Herrera's cracking method.
| [
{
"created": "Thu, 26 Oct 2023 17:58:30 GMT",
"version": "v1"
}
] | 2023-10-27 | [
[
"Jaiswal",
"Annu",
""
],
[
"Kumar",
"Rajesh",
""
],
[
"Srivastava",
"Sudhir Kumar",
""
],
[
"Govender",
"Megandhren",
""
],
[
"Pacif",
"Shibesh Kumar Jas",
""
]
] | In this work, we have investigated a novel aspect of black hole (BH) formation during the collapse of a self-gravitating configuration. The exact solution of the Einstein field equations is obtained in a model-independent way by considering a parametrization of the expansion scalar ($\Theta$) in the background of spherically symmetric space-time geometry governed by the FLRW metric. Smooth matching of the interior solution with the Schwarzschild exterior metric across the boundary hypersurface of the star, together with the condition that the mass function $m(t,r)$ is equal to Schwarzschild mass $M$, is used to obtain all the physical and geometrical parameters in terms of the stellar mass. The four known massive stars namely $R136a3$, $Melnick$, $R136c$, and $R136b$ with their known astrophysical data (mass, radius, and present age) are used to study the physics of the model both numerically and graphically. We demonstrate that the formation of the apparent horizon occurs earlier than the singular state that is, the model of massive stars would inevitably lead to the formation of a BH as their end state. We have conducted an analysis indicating that the lifespans of massive stars are closely related to their respective masses. Our findings demonstrate that more massive stars exhibit considerably shorter lifespans in comparison to their lighter counterparts. Thus, the presented model corresponds to the evolutionary stages of astrophysical stellar objects and theoretically predicts their possible lifespan. We have also shown that our model satisfies the energy conditions and stability requirements via Herrera's cracking method. |
2206.11685 | Ho Seong Hwang | Youngsub Yoon, Jong-Chul Park, Ho Seong Hwang | Understanding Galaxy Rotation Curves with Verlinde's Emergent Gravity | 11 pages, 2 figures. To appear in Classical and Quantum Gravity | null | 10.1088/1361-6382/acaae6 | null | gr-qc astro-ph.GA hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the results from the analysis of galaxy rotation curves with
Verlinde's emergent gravity. We use the data in the SPARC (Spitzer Photometry
and Accurate Rotation Curves) database, which contains a sample of 175 nearby
disk galaxies with 3.6 $\mu$m surface photometry and rotation curves. We
compute the gravitational acceleration at different galactocentric radii
expected from the baryon distribution of the galaxies with the emergent
gravity, and compare it with the observed gravitational acceleration derived
from galactic rotation curves. The predicted and observed accelerations agree
well with a mean offset $\mu{\rm [log(g_{obs})-log(g_{Ver})]}=-0.060\pm0.004$
and a scatter $\sigma{\rm [log(g_{obs})-log(g_{Ver})]}=0.137\pm0.004$ by
assuming a de Sitter universe. These offset and scatter become smaller when we
assume a more realistic universe, quasi de Sitter universe, as
$\mu=-0.027\pm0.003$ and $\sigma=0.129\pm0.003$. Our results suggest that
Verlinde's emergent gravity could be a good solution to the missing mass
problem without introducing dark matter.
| [
{
"created": "Thu, 23 Jun 2022 13:24:14 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Jul 2022 11:56:23 GMT",
"version": "v2"
},
{
"created": "Fri, 16 Dec 2022 04:01:58 GMT",
"version": "v3"
}
] | 2022-12-28 | [
[
"Yoon",
"Youngsub",
""
],
[
"Park",
"Jong-Chul",
""
],
[
"Hwang",
"Ho Seong",
""
]
] | We present the results from the analysis of galaxy rotation curves with Verlinde's emergent gravity. We use the data in the SPARC (Spitzer Photometry and Accurate Rotation Curves) database, which contains a sample of 175 nearby disk galaxies with 3.6 $\mu$m surface photometry and rotation curves. We compute the gravitational acceleration at different galactocentric radii expected from the baryon distribution of the galaxies with the emergent gravity, and compare it with the observed gravitational acceleration derived from galactic rotation curves. The predicted and observed accelerations agree well with a mean offset $\mu{\rm [log(g_{obs})-log(g_{Ver})]}=-0.060\pm0.004$ and a scatter $\sigma{\rm [log(g_{obs})-log(g_{Ver})]}=0.137\pm0.004$ by assuming a de Sitter universe. These offset and scatter become smaller when we assume a more realistic universe, quasi de Sitter universe, as $\mu=-0.027\pm0.003$ and $\sigma=0.129\pm0.003$. Our results suggest that Verlinde's emergent gravity could be a good solution to the missing mass problem without introducing dark matter. |
1612.03065 | Marco Letizia | Marco Letizia and Stefano Liberati | Deformed relativity symmetries and the local structure of spacetime | 20 pages | Phys. Rev. D 95, 046007 (2017) | 10.1103/PhysRevD.95.046007 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A spacetime interpretation of deformed relativity symmetry groups was
recently proposed by resorting to Finslerian geometries, seen as the outcome of
a continuous limit endowed with first order corrections from the quantum
gravity regime. In this work we further investigate such connection between
deformed algebras and Finslerian geometries by showing that the Finsler
geometries associated to the generalisation of the Poincar\'{e} group (the so
called $\kappa$-Poincar\'{e} Hopf algebra) are maximally symmetric spacetimes
which are also of the Berwald type: Finslerian spacetimes for which the
connections are substantially Riemannian, belonging to the unique class for
which the weak equivalence principle still holds. We also extend this analysis
by considering a generalization of the de Sitter group (the so called $q$-de
Sitter group) and showing that its associated Finslerian geometry reproduces
locally the one from the $\kappa$-Poincar\'{e} group and that itself can be
recast in a Berwald form in an appropriate limit.
| [
{
"created": "Fri, 9 Dec 2016 15:49:15 GMT",
"version": "v1"
}
] | 2017-02-22 | [
[
"Letizia",
"Marco",
""
],
[
"Liberati",
"Stefano",
""
]
] | A spacetime interpretation of deformed relativity symmetry groups was recently proposed by resorting to Finslerian geometries, seen as the outcome of a continuous limit endowed with first order corrections from the quantum gravity regime. In this work we further investigate such connection between deformed algebras and Finslerian geometries by showing that the Finsler geometries associated to the generalisation of the Poincar\'{e} group (the so called $\kappa$-Poincar\'{e} Hopf algebra) are maximally symmetric spacetimes which are also of the Berwald type: Finslerian spacetimes for which the connections are substantially Riemannian, belonging to the unique class for which the weak equivalence principle still holds. We also extend this analysis by considering a generalization of the de Sitter group (the so called $q$-de Sitter group) and showing that its associated Finslerian geometry reproduces locally the one from the $\kappa$-Poincar\'{e} group and that itself can be recast in a Berwald form in an appropriate limit. |
1511.08263 | Carlos Alex Souza da Silva Dr | M.B. Cruz, C.A.S. Silva and F.A. Brito | Gravitational axial perturbations and quasinormal modes of loop quantum
black holes | Accepted for publication in EPJC | Eur. Phys. J. C (2019) 79: 157 | 10.1140/epjc/s10052-019-6565-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Loop Quantum Gravity (LQG) is a theory that proposes a way to model the
behavior of the spacetime in situations where its atomic characteristic arises.
Among these situations, the spacetime behavior near the Big Bang or black
hole's singularity. The detection of gravitational waves, on the other hand,
has opened the way to new perspectives in the investigation of the spacetime
structure. In this work, by the use of a WKB method introduced by Schutz and
Will \cite{Schutz:1985zz}, and after improved by Iyer and Will
\cite{s.iyer-prd35}, we study the gravitational wave spectrum emitted by loop
quantum black holes, which correspond to a quantized version of the
Schwarzschild spacetime by LQG techniques. From the results obtained, loop
quantum black holes have been shown stable under axial gravitational
perturbations.
| [
{
"created": "Thu, 26 Nov 2015 01:10:29 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Aug 2017 14:56:48 GMT",
"version": "v2"
},
{
"created": "Thu, 7 Mar 2019 02:34:34 GMT",
"version": "v3"
}
] | 2019-03-08 | [
[
"Cruz",
"M. B.",
""
],
[
"Silva",
"C. A. S.",
""
],
[
"Brito",
"F. A.",
""
]
] | Loop Quantum Gravity (LQG) is a theory that proposes a way to model the behavior of the spacetime in situations where its atomic characteristic arises. Among these situations, the spacetime behavior near the Big Bang or black hole's singularity. The detection of gravitational waves, on the other hand, has opened the way to new perspectives in the investigation of the spacetime structure. In this work, by the use of a WKB method introduced by Schutz and Will \cite{Schutz:1985zz}, and after improved by Iyer and Will \cite{s.iyer-prd35}, we study the gravitational wave spectrum emitted by loop quantum black holes, which correspond to a quantized version of the Schwarzschild spacetime by LQG techniques. From the results obtained, loop quantum black holes have been shown stable under axial gravitational perturbations. |
2308.00976 | Wei Zeng | Wei Zeng, Yi Ling, Qing-Quan Jiang, Guo-Ping Li | Accretion Disk for regular black holes with sub-Planckian curvature | 26 pages,9 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We investigate the accretion disk for a sort of regular black holes which are
characterized by sub-Planckian curvature and Minkowskian core. We derive null
geodesics outside the horizon of such regular black holes and analyze the
feature of the light rays from the accretion disk which can be classified into
direct emission, lensed rings, and photon rings. We find that the observed
brightness under different emission models is mainly determined by direct
emission, while the contribution from the flux of the lensed and photon rings
is limited. By comparing with Bardeen black hole with a dS core, it is found
that the black hole with a Minkowskian core exhibits distinct astronomical
optical features when surrounded by accretion disk, which potentially provides
a way to distinguish these two sorts of black holes by astronomical
observation.
| [
{
"created": "Wed, 2 Aug 2023 07:15:18 GMT",
"version": "v1"
}
] | 2023-08-03 | [
[
"Zeng",
"Wei",
""
],
[
"Ling",
"Yi",
""
],
[
"Jiang",
"Qing-Quan",
""
],
[
"Li",
"Guo-Ping",
""
]
] | We investigate the accretion disk for a sort of regular black holes which are characterized by sub-Planckian curvature and Minkowskian core. We derive null geodesics outside the horizon of such regular black holes and analyze the feature of the light rays from the accretion disk which can be classified into direct emission, lensed rings, and photon rings. We find that the observed brightness under different emission models is mainly determined by direct emission, while the contribution from the flux of the lensed and photon rings is limited. By comparing with Bardeen black hole with a dS core, it is found that the black hole with a Minkowskian core exhibits distinct astronomical optical features when surrounded by accretion disk, which potentially provides a way to distinguish these two sorts of black holes by astronomical observation. |
1410.0792 | Bert Schroer | Bert Schroer | A Hilbert Space setting for higher spin interactions which replaces
Gauge Theory | 26 pages, additional results, special emphasis on results from
Hilbert space positivity which go beyond indefinite metric gauge theory | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The recently discovered Hilbert space description of renormalizable
interactions of higher spin (equal or bigger than 1) fields requires to replace
the pointlocal s=1 vectorpotentials of indefinite metric (Krein space) BRST
gauge theory by their stringlike counterpart in Hilbert space. It is shown that
the Hilbert space positivity leads to new properties outside the conceptual
range of the gauge theoretic description: topological aspects of Wilson loops,
induced normalization terms (in particular Mexican hat type potentials for
massive vectormesons coupled to Hermitian scalar field) and a possible role of
string-localization in confinerment.
| [
{
"created": "Fri, 3 Oct 2014 09:36:10 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Oct 2014 17:12:23 GMT",
"version": "v2"
},
{
"created": "Wed, 29 Oct 2014 14:18:42 GMT",
"version": "v3"
},
{
"created": "Wed, 12 Nov 2014 09:27:50 GMT",
"version": "v4"
}
] | 2014-11-13 | [
[
"Schroer",
"Bert",
""
]
] | The recently discovered Hilbert space description of renormalizable interactions of higher spin (equal or bigger than 1) fields requires to replace the pointlocal s=1 vectorpotentials of indefinite metric (Krein space) BRST gauge theory by their stringlike counterpart in Hilbert space. It is shown that the Hilbert space positivity leads to new properties outside the conceptual range of the gauge theoretic description: topological aspects of Wilson loops, induced normalization terms (in particular Mexican hat type potentials for massive vectormesons coupled to Hermitian scalar field) and a possible role of string-localization in confinerment. |
gr-qc/0409040 | C\'edric Leygnac | C\'edric Leygnac | Non-asymptotically flat black holes/branes | Ph. D. thesis, in french, 132 pages, 16 eps figures | null | null | LAPTH-these-1060/04 | gr-qc hep-th | null | In the framework of string-inspired dilatonic gravity theories (from 4 to $D$
space-time dimensions), we construct new non-asymptotically flat black hole or
black brane solutions. For particular values of the dilatonic coupling
constant, we generalize static solutions to rotating ones, using the target
space isometry group. We compute their masses and their angular momentum using
the modern approach to the computation of energy in General Relativity, the
quasilocal formalism, and we check the agreement of these solutions with the
first law of black hole thermodynamics. Finally, we study a new black hole
family in the 2+1 dimensional theory of Topologically Massive Gravity.
| [
{
"created": "Thu, 9 Sep 2004 09:00:43 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Leygnac",
"Cédric",
""
]
] | In the framework of string-inspired dilatonic gravity theories (from 4 to $D$ space-time dimensions), we construct new non-asymptotically flat black hole or black brane solutions. For particular values of the dilatonic coupling constant, we generalize static solutions to rotating ones, using the target space isometry group. We compute their masses and their angular momentum using the modern approach to the computation of energy in General Relativity, the quasilocal formalism, and we check the agreement of these solutions with the first law of black hole thermodynamics. Finally, we study a new black hole family in the 2+1 dimensional theory of Topologically Massive Gravity. |
2103.14725 | Brandon Mattingly | Brandon Mattingly | Curvature Invariants for Wormholes and Warped Spacetimes | 137 pages, 45 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The Carminati and McLenaghan (CM) curvature invariants are powerful tools for
probing spacetimes. Henry et al. formulated a method of plotting the CM
curvature invariants to study black holes. The CM curvature invariants are
scalar functions of the underlying spacetime. Consequently, they are
independent of the chosen coordinates and characterize the spacetime. For Class
B1 spacetimes, there are four independent CM curvature invariants: R, r1, r2,
and w2. Lorentzian traversable wormholes and warp drives are two theoretical
solutions to Einstein's field equations, which allow faster-than-light (FTL)
transport. The CM curvature invariants are plotted and analyzed for these
specific FTL spacetimes: (i) the Thin-Shell Flat-Face wormhole, (ii) the
Morris-Thorne wormhole, (iii) the Thin-Shell Schwarzschild wormhole, (iv) the
exponential metric, (v) the Alcubierre metric at constant velocity, (vi) the
Nat\'ario metric at constant velocity, and (vii) the Nat\'ario metric at an
accelerating velocity. Plots of the wormhole CM invariants confirm their
traversability and show how to distinguish the wormholes. The warp drive CM
invariants reveal key features such as a flat harbor in the center of each warp
bubble, a dynamic wake for each warp bubble, and rich internal structure(s) of
each warp bubble.
| [
{
"created": "Fri, 26 Mar 2021 20:38:08 GMT",
"version": "v1"
}
] | 2021-03-30 | [
[
"Mattingly",
"Brandon",
""
]
] | The Carminati and McLenaghan (CM) curvature invariants are powerful tools for probing spacetimes. Henry et al. formulated a method of plotting the CM curvature invariants to study black holes. The CM curvature invariants are scalar functions of the underlying spacetime. Consequently, they are independent of the chosen coordinates and characterize the spacetime. For Class B1 spacetimes, there are four independent CM curvature invariants: R, r1, r2, and w2. Lorentzian traversable wormholes and warp drives are two theoretical solutions to Einstein's field equations, which allow faster-than-light (FTL) transport. The CM curvature invariants are plotted and analyzed for these specific FTL spacetimes: (i) the Thin-Shell Flat-Face wormhole, (ii) the Morris-Thorne wormhole, (iii) the Thin-Shell Schwarzschild wormhole, (iv) the exponential metric, (v) the Alcubierre metric at constant velocity, (vi) the Nat\'ario metric at constant velocity, and (vii) the Nat\'ario metric at an accelerating velocity. Plots of the wormhole CM invariants confirm their traversability and show how to distinguish the wormholes. The warp drive CM invariants reveal key features such as a flat harbor in the center of each warp bubble, a dynamic wake for each warp bubble, and rich internal structure(s) of each warp bubble. |
2101.03865 | Parth Bambhaniya | Parth Bambhaniya, Dipanjan Dey, Ashok B. Joshi, Pankaj S. Joshi,
Divyesh N. Solanki, Aadarsh Mehta | Shadows and negative precession in non-Kerr spacetime | 13 pages, 20 figures | Phys. Rev. D 103, 084005 (2021) | 10.1103/PhysRevD.103.084005 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | It is now known that the shadow is not only the property of a black hole, it
can also be cast by other compact objects like naked singularities. However,
there exist some novel features of the shadow of the naked singularities which
are elaborately discussed in some recent articles. In the earlier literature,
it is also shown that a naked singularity may admit negative precession of
bound timelike orbits which cannot be seen in Schwarzschild and Kerr black hole
spacetimes. This distinguishable behavior of timelike bound orbit in the
presence of the naked singularity along with the novel features of the shadow
may be useful to distinguish between a black hole and a naked singularity
observationally. However, in this paper, it is shown that deformed Kerr
spacetime can allow negative precession of bound timelike orbits when the
central singularity of that spacetime is naked. We also show that negative
precession and shadow both can exist simultaneously in deformed Kerr naked
singularity spacetime. Therefore, any observational evidence of negative
precession of bound orbits, along with the central shadow may indicate the
presence of a deformed Kerr naked singularity.
| [
{
"created": "Mon, 11 Jan 2021 13:26:26 GMT",
"version": "v1"
}
] | 2021-04-14 | [
[
"Bambhaniya",
"Parth",
""
],
[
"Dey",
"Dipanjan",
""
],
[
"Joshi",
"Ashok B.",
""
],
[
"Joshi",
"Pankaj S.",
""
],
[
"Solanki",
"Divyesh N.",
""
],
[
"Mehta",
"Aadarsh",
""
]
] | It is now known that the shadow is not only the property of a black hole, it can also be cast by other compact objects like naked singularities. However, there exist some novel features of the shadow of the naked singularities which are elaborately discussed in some recent articles. In the earlier literature, it is also shown that a naked singularity may admit negative precession of bound timelike orbits which cannot be seen in Schwarzschild and Kerr black hole spacetimes. This distinguishable behavior of timelike bound orbit in the presence of the naked singularity along with the novel features of the shadow may be useful to distinguish between a black hole and a naked singularity observationally. However, in this paper, it is shown that deformed Kerr spacetime can allow negative precession of bound timelike orbits when the central singularity of that spacetime is naked. We also show that negative precession and shadow both can exist simultaneously in deformed Kerr naked singularity spacetime. Therefore, any observational evidence of negative precession of bound orbits, along with the central shadow may indicate the presence of a deformed Kerr naked singularity. |
gr-qc/0404092 | Bela Szilagyi | Maria Babiuc, Bela Szilagyi, Jeffrey Winicour | Some mathematical problems in numerical relativity | 17 pages, 12 graphs (eps format) | Lect.Notes Phys.692:251-274,2006 | 10.1007/11550259_12 | null | gr-qc | null | The main goal of numerical relativity is the long time simulation of highly
nonlinear spacetimes that cannot be treated by perturbation theory. This
involves analytic, computational and physical issues. At present, the major
impasses to achieving global simulations of physical usefulness are of an
analytic/computational nature. We present here some examples of how analytic
insight can lend useful guidance for the improvement of numerical approaches.
| [
{
"created": "Wed, 21 Apr 2004 19:56:48 GMT",
"version": "v1"
}
] | 2011-04-21 | [
[
"Babiuc",
"Maria",
""
],
[
"Szilagyi",
"Bela",
""
],
[
"Winicour",
"Jeffrey",
""
]
] | The main goal of numerical relativity is the long time simulation of highly nonlinear spacetimes that cannot be treated by perturbation theory. This involves analytic, computational and physical issues. At present, the major impasses to achieving global simulations of physical usefulness are of an analytic/computational nature. We present here some examples of how analytic insight can lend useful guidance for the improvement of numerical approaches. |
1401.3054 | Jing-Bo Wang | Jingbo Wang | The Entropy of BTZ Black Hole from Loop Quantum Gravity | 12 page | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we calculated the entropy of the BTZ black hole in the
framework of loop quantum gravity. We got the result that the horizon degrees
of freedom can be described by the 2D SO(1,1) punctured BF theory. Finally we
got the area law for the entropy of BTZ black hole.
| [
{
"created": "Tue, 14 Jan 2014 02:40:55 GMT",
"version": "v1"
}
] | 2014-01-15 | [
[
"Wang",
"Jingbo",
""
]
] | In this paper, we calculated the entropy of the BTZ black hole in the framework of loop quantum gravity. We got the result that the horizon degrees of freedom can be described by the 2D SO(1,1) punctured BF theory. Finally we got the area law for the entropy of BTZ black hole. |
1104.4662 | Peter K.F. Kuhfittig | Peter K. F. Kuhfittig | On the feasibility of charged wormholes | 6 pages, 1 figure | Cent. Eur. J. Phys., vol. 9, 1144 (2011) | 10.2478/s11534-011-0043-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | While wormhole spacetimes are predictions of the general theory of
relativity, specific solutions may not be compatible with quantum field theory.
This paper modifies the charged wormhole model of Kim and Lee with the aim of
satisfying an extended version of a quantum inequality due to Ford and Roman.
The modified metric may be viewed as a solution of the Einstein field equations
representing a charged wormhole that is compatible with quantum field theory.
| [
{
"created": "Sun, 24 Apr 2011 22:19:22 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Jun 2011 14:44:06 GMT",
"version": "v2"
},
{
"created": "Tue, 20 Dec 2011 00:33:41 GMT",
"version": "v3"
}
] | 2015-05-28 | [
[
"Kuhfittig",
"Peter K. F.",
""
]
] | While wormhole spacetimes are predictions of the general theory of relativity, specific solutions may not be compatible with quantum field theory. This paper modifies the charged wormhole model of Kim and Lee with the aim of satisfying an extended version of a quantum inequality due to Ford and Roman. The modified metric may be viewed as a solution of the Einstein field equations representing a charged wormhole that is compatible with quantum field theory. |
gr-qc/0009082 | Tekin Dereli | T. Dereli, O. Sarioglu (METU, Ankara) | Topologically massive gravity and black holes in three dimensions | 4 pages REVTEX file, no figures | null | null | null | gr-qc | null | We obtain a general class of exact solutions to topologically massive gravity
with or without a negative cosmological constant. In the first case, we show
that the solution is supersymmetric and asymptotically approaches the extremal
BTZ black hole solution, while in the latter case it goes to flat space-time.
| [
{
"created": "Mon, 25 Sep 2000 11:30:15 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Dereli",
"T.",
"",
"METU, Ankara"
],
[
"Sarioglu",
"O.",
"",
"METU, Ankara"
]
] | We obtain a general class of exact solutions to topologically massive gravity with or without a negative cosmological constant. In the first case, we show that the solution is supersymmetric and asymptotically approaches the extremal BTZ black hole solution, while in the latter case it goes to flat space-time. |
1110.0079 | Manuel Rodrigues | Glauber Tadaiesky Marques, Manuel E. Rodrigues | Equivalence of the Hawking temperature in conformal frames | 21 pages | Eur. Phys. J. C 72: 1891 (2012) | 10.1140/epjc/s10052-012-1891-7 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The conformal invariance of the Hawking temperature, conjectured for the
asymptotically flat and stationary black holes by Jacobson and Kang, is
semiclassically evaluated for a simple particular case of symmetrical
spherically and non asymptotically flat black hole. By using the Bogoliubov
coefficients, the metric euclideanization, the reflection coefficient and the
gravitational anomaly, as methods of calculating the Hawking temperature, we
find that it is invariant under a specific conformal transformation of the
metric. We discuss briefly the results for each method.
| [
{
"created": "Sat, 1 Oct 2011 06:30:44 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Oct 2011 19:22:16 GMT",
"version": "v2"
}
] | 2015-03-13 | [
[
"Marques",
"Glauber Tadaiesky",
""
],
[
"Rodrigues",
"Manuel E.",
""
]
] | The conformal invariance of the Hawking temperature, conjectured for the asymptotically flat and stationary black holes by Jacobson and Kang, is semiclassically evaluated for a simple particular case of symmetrical spherically and non asymptotically flat black hole. By using the Bogoliubov coefficients, the metric euclideanization, the reflection coefficient and the gravitational anomaly, as methods of calculating the Hawking temperature, we find that it is invariant under a specific conformal transformation of the metric. We discuss briefly the results for each method. |
0804.3322 | Jonathan R. Gair | Jonathan R. Gair, Edward K. Porter, Stanislav Babak, Leor Barack | A Constrained Metropolis-Hastings Search for EMRIs in the Mock LISA Data
Challenge 1B | 13 pages, 3 figures, to be published in proceedings of the 12th
Gravitational Wave Data Analysis Workshop; v2 has minor changes for
consistency with accepted version | Class.Quant.Grav.25:184030,2008 | 10.1088/0264-9381/25/18/184030 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe a search for the extreme-mass-ratio inspiral sources in the Round
1B Mock LISA Data Challenge data sets. The search algorithm is a Monte-Carlo
search based on the Metropolis-Hastings algorithm, but also incorporates
simulated, thermostated and time annealing, plus a harmonic identification
stage designed to reduce the chance of the chain locking onto secondary maxima.
In this paper, we focus on describing the algorithm that we have been
developing. We give the results of the search of the Round 1B data, although
parameter recovery has improved since that deadline. Finally, we describe
several modifications to the search pipeline that we are currently
investigating for incorporation in future searches.
| [
{
"created": "Mon, 21 Apr 2008 14:30:02 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Jul 2008 14:40:45 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Gair",
"Jonathan R.",
""
],
[
"Porter",
"Edward K.",
""
],
[
"Babak",
"Stanislav",
""
],
[
"Barack",
"Leor",
""
]
] | We describe a search for the extreme-mass-ratio inspiral sources in the Round 1B Mock LISA Data Challenge data sets. The search algorithm is a Monte-Carlo search based on the Metropolis-Hastings algorithm, but also incorporates simulated, thermostated and time annealing, plus a harmonic identification stage designed to reduce the chance of the chain locking onto secondary maxima. In this paper, we focus on describing the algorithm that we have been developing. We give the results of the search of the Round 1B data, although parameter recovery has improved since that deadline. Finally, we describe several modifications to the search pipeline that we are currently investigating for incorporation in future searches. |
gr-qc/0101080 | Luca Bombelli | Luca Bombelli | Statistical geometry of random weave states | 10 pages, LaTeX, submitted to the Proceedings of the IX Marcel
Grossmann Meeting, Rome, July 2-8, 2000 | null | 10.1142/9789812777386_0217 | null | gr-qc | null | I describe the first steps in the construction of semiclassical states for
non-perturbative canonical quantum gravity using ideas from classical,
Riemannian statistical geometry and results from quantum geometry of spin
network states. In particular, I concentrate on how those techniques are
applied to the construction of random spin networks, and the calculation of
their contribution to areas and volumes.
| [
{
"created": "Fri, 19 Jan 2001 05:10:15 GMT",
"version": "v1"
}
] | 2017-08-23 | [
[
"Bombelli",
"Luca",
""
]
] | I describe the first steps in the construction of semiclassical states for non-perturbative canonical quantum gravity using ideas from classical, Riemannian statistical geometry and results from quantum geometry of spin network states. In particular, I concentrate on how those techniques are applied to the construction of random spin networks, and the calculation of their contribution to areas and volumes. |
1512.07659 | Francisco Lobo | Francisco S. N. Lobo, Prado Mart\'in-Moruno, Nadiezhda
Montelongo-Garc\'ia, Matt Visser | Novel stability approach of thin-shell gravastars | 6 pages; contribution to the proceedings of the "The Fourteenth
Marcel Grossmann Meeting on General Relativity", University of Rome "La
Sapienza", Rome, July 12-18, 2015, based on an invited talk delivered at the
BS1-"Black Hole foils, Boson stars" parallel session | null | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We develop an extremely general and robust framework that can be adapted to
wide classes of generic spherically symmetric thin-shell gravastars. The thin
shell (transition layer) will be permitted to move freely in the bulk
spacetimes, permitting a fully dynamic analysis. This will then allow us to
perform a general stability analysis, where it is explicitly shown that
stability of the gravastar is related to the properties of the matter residing
in the thin-shell transition layer.
| [
{
"created": "Wed, 23 Dec 2015 23:08:14 GMT",
"version": "v1"
}
] | 2015-12-25 | [
[
"Lobo",
"Francisco S. N.",
""
],
[
"Martín-Moruno",
"Prado",
""
],
[
"Montelongo-García",
"Nadiezhda",
""
],
[
"Visser",
"Matt",
""
]
] | We develop an extremely general and robust framework that can be adapted to wide classes of generic spherically symmetric thin-shell gravastars. The thin shell (transition layer) will be permitted to move freely in the bulk spacetimes, permitting a fully dynamic analysis. This will then allow us to perform a general stability analysis, where it is explicitly shown that stability of the gravastar is related to the properties of the matter residing in the thin-shell transition layer. |
2111.03066 | V H Satheeshkumar | V. H. Satheeshkumar | Nature of Singularities in Vector-Tensor Theories of Gravity | 9 pages, Invited parallel session talk at MG16, to appear in the
Proceedings of the Sixteenth Marcel Grossmann Meeting | The Sixteenth Marcel Grossmann Meeting, pp. 1095-1103 (2023) | 10.1142/9789811269776_0086 | null | gr-qc astro-ph.CO astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | The Vector-Tensor (VT) theories of gravity are a class of alternative
theories to General Relativity (GR) that are characterized by the presence of a
dynamical vector field besides the metric. They are studied in attempts to
understand spontaneous Lorentz violation, to generate massive gravitons, and as
models of dark matter and dark energy. In this article, I outline how the
nature of singularities and horizons in VT theories differ greatly from GR even
under the same ordinary conditions. This is illustrated with Einsteinaether
theory where vacuum black hole solutions have naked singularities and vacuum
cosmological solutions have new singularities that are otherwise absent in GR.
It would be interesting to explore these deviations using gravitational waves
| [
{
"created": "Thu, 4 Nov 2021 16:41:20 GMT",
"version": "v1"
}
] | 2023-01-31 | [
[
"Satheeshkumar",
"V. H.",
""
]
] | The Vector-Tensor (VT) theories of gravity are a class of alternative theories to General Relativity (GR) that are characterized by the presence of a dynamical vector field besides the metric. They are studied in attempts to understand spontaneous Lorentz violation, to generate massive gravitons, and as models of dark matter and dark energy. In this article, I outline how the nature of singularities and horizons in VT theories differ greatly from GR even under the same ordinary conditions. This is illustrated with Einsteinaether theory where vacuum black hole solutions have naked singularities and vacuum cosmological solutions have new singularities that are otherwise absent in GR. It would be interesting to explore these deviations using gravitational waves |
2211.10394 | Michael Hobson | Michael Hobson | New form of the Kerr-Newman solution | 4 pages, no figures, accepted as a Letter by PRD. Contains minor
updates to match accepted version | null | 10.1103/PhysRevD.107.L021501 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new form of the Kerr-Newman solution is presented. The solution involves a
time coordinate which represents the local proper time for a charged massive
particle released from rest at spatial infinity. The chosen coordinates ensure
that the solution is well-behaved at horizons and enable an intuitive
description of many physical phenomena. If the charge of the particle $e = 0$,
the coordinates reduce to Doran coordinates for the Kerr solution with the
replacement $M \to M - Q^2/(2r)$, where $M$ and $Q$ are the mass and charge of
the black hole, respectively. Such coordinates are valid only for $r \ge
Q^2/(2M)$, however, which corresponds to the region that a neutral particle
released from rest at infinity can penetrate. By contrast, for $e \neq 0$ and
of opposite sign to $Q$, the new coordinates have a progressively extended
range of validity as $|e|$ increases and tend to advanced Eddington-Finkelstein
(EF) null coordinates as $|e| \to \infty$, hence becoming global in this limit.
The Kerr solution (i.e.\ with $Q=0$) may also be written in terms of the new
coordinates by setting $eQ = -\alpha$, where $\alpha$ is a real parameter
unrelated to charge; in this case the coordinate system is global for all
non-negative values of $\alpha$ and the limits $\alpha = 0$ and $\alpha \to
\infty$ correspond to Doran coordinates and advanced EF null coordinates,
respectively, without any need to transform between them.
| [
{
"created": "Fri, 18 Nov 2022 17:52:06 GMT",
"version": "v1"
},
{
"created": "Sat, 21 Jan 2023 13:54:19 GMT",
"version": "v2"
}
] | 2023-02-15 | [
[
"Hobson",
"Michael",
""
]
] | A new form of the Kerr-Newman solution is presented. The solution involves a time coordinate which represents the local proper time for a charged massive particle released from rest at spatial infinity. The chosen coordinates ensure that the solution is well-behaved at horizons and enable an intuitive description of many physical phenomena. If the charge of the particle $e = 0$, the coordinates reduce to Doran coordinates for the Kerr solution with the replacement $M \to M - Q^2/(2r)$, where $M$ and $Q$ are the mass and charge of the black hole, respectively. Such coordinates are valid only for $r \ge Q^2/(2M)$, however, which corresponds to the region that a neutral particle released from rest at infinity can penetrate. By contrast, for $e \neq 0$ and of opposite sign to $Q$, the new coordinates have a progressively extended range of validity as $|e|$ increases and tend to advanced Eddington-Finkelstein (EF) null coordinates as $|e| \to \infty$, hence becoming global in this limit. The Kerr solution (i.e.\ with $Q=0$) may also be written in terms of the new coordinates by setting $eQ = -\alpha$, where $\alpha$ is a real parameter unrelated to charge; in this case the coordinate system is global for all non-negative values of $\alpha$ and the limits $\alpha = 0$ and $\alpha \to \infty$ correspond to Doran coordinates and advanced EF null coordinates, respectively, without any need to transform between them. |
2206.13744 | Yehui Hou | Yehui Hou, Zhenyu Zhang, Haopeng Yan, Minyong Guo, Bin Chen | Image of Kerr-Melvin black hole with thin accretion disk | 24 pages, 10 figures | Phys.Rev.D 106,064058 (2022) | 10.1103/PhysRevD.106.064058 | null | gr-qc astro-ph.HE | http://creativecommons.org/publicdomain/zero/1.0/ | In this present work, we study the observational appearance of Kerr-Melvin
black hole (KMBH) illuminated by an accretion disk. The accretion disk is
assumed to be located on the equatorial plane and be thin both geometrically
and optically. Considering the fact that outside the innermost stable circular
orbit (ISCO) the accretion flow moves in prograde or retrograde circular orbit
and falls towards the horizon along plunging orbit inside the ISCO, we develop
the numerical backward ray-tracing method and obtain the images of KMBH
accompanying with the accretion disk for various black hole spins, strengths of
magnetic fields and inclination angles of observers. We present the intensity
distribution horizontally and longitudinally and show the profiles of the
red-shift for the direct and lensed images. Our study suggests that the inner
shadow and critical curves can be used to estimate the magnetic field around a
black hole without degeneration.
| [
{
"created": "Tue, 28 Jun 2022 04:03:39 GMT",
"version": "v1"
},
{
"created": "Fri, 30 Sep 2022 15:56:34 GMT",
"version": "v2"
},
{
"created": "Tue, 4 Oct 2022 10:31:24 GMT",
"version": "v3"
}
] | 2022-10-05 | [
[
"Hou",
"Yehui",
""
],
[
"Zhang",
"Zhenyu",
""
],
[
"Yan",
"Haopeng",
""
],
[
"Guo",
"Minyong",
""
],
[
"Chen",
"Bin",
""
]
] | In this present work, we study the observational appearance of Kerr-Melvin black hole (KMBH) illuminated by an accretion disk. The accretion disk is assumed to be located on the equatorial plane and be thin both geometrically and optically. Considering the fact that outside the innermost stable circular orbit (ISCO) the accretion flow moves in prograde or retrograde circular orbit and falls towards the horizon along plunging orbit inside the ISCO, we develop the numerical backward ray-tracing method and obtain the images of KMBH accompanying with the accretion disk for various black hole spins, strengths of magnetic fields and inclination angles of observers. We present the intensity distribution horizontally and longitudinally and show the profiles of the red-shift for the direct and lensed images. Our study suggests that the inner shadow and critical curves can be used to estimate the magnetic field around a black hole without degeneration. |
gr-qc/0611149 | Daniel Barraco | A.J.Bustelo and D.E.Barraco | Equilibrium hydrostatic equation and Newtonian limit of the singular
f(R) gravity | Revised version, to appear in Classical and Quantum Gravity. | Class.Quant.Grav.24:2333-2342,2007 | 10.1088/0264-9381/24/9/011 | null | gr-qc astro-ph hep-th | null | We derive the equilibrium hydrostatic equation of a spherical star for any
gravitational Lagrangian density of the form $L=\sqrt{-g}f(R)$. The Palatini
variational principle for the Helmholtz Lagrangian in the Einstein gauge is
used to obtain the field equations in this gauge. The equilibrium hydrostatic
equation is obtained and is used to study the Newtonian limit for
$f(R)=R-\frac{a^{2}}{3R}$. The same procedure is carried out for the more
generally case $f(R)=R-\frac{1}{n+2}\frac{a^{n+1}}{R^{n}}$ giving a good
Newtonian limit.
| [
{
"created": "Tue, 28 Nov 2006 21:26:31 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Apr 2007 16:39:27 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Bustelo",
"A. J.",
""
],
[
"Barraco",
"D. E.",
""
]
] | We derive the equilibrium hydrostatic equation of a spherical star for any gravitational Lagrangian density of the form $L=\sqrt{-g}f(R)$. The Palatini variational principle for the Helmholtz Lagrangian in the Einstein gauge is used to obtain the field equations in this gauge. The equilibrium hydrostatic equation is obtained and is used to study the Newtonian limit for $f(R)=R-\frac{a^{2}}{3R}$. The same procedure is carried out for the more generally case $f(R)=R-\frac{1}{n+2}\frac{a^{n+1}}{R^{n}}$ giving a good Newtonian limit. |
0812.0420 | Ertan G\"okl\"u | H.-P. Breuer, E. G\"okl\"u and C. L\"ammerzahl | Metric fluctuations and decoherence | 7 pages | null | 10.1088/0264-9381/26/10/105012 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently a model of metric fluctuations has been proposed which yields an
effective Schr\"odinger equation for a quantum particle with a modified
inertial mass, leading to a violation of the weak equivalence principle. The
renormalization of the inertial mass tensor results from a local space average
over the fluctuations of the metric over a fixed background metric. Here, we
demonstrate that the metric fluctuations of this model lead to a further
physical effect, namely to an effective decoherence of the quantum particle. We
derive a quantum master equation for the particle's density matrix, discuss in
detail its dissipation and decoherence properties, and estimate the
corresponding decoherence time scales. By contrast to other models discussed in
the literature, in the present approach the metric fluctuations give rise to a
decay of the coherences in the energy representation, i. e., to a localization
in energy space.
| [
{
"created": "Tue, 2 Dec 2008 03:20:10 GMT",
"version": "v1"
}
] | 2015-06-26 | [
[
"Breuer",
"H. -P.",
""
],
[
"Göklü",
"E.",
""
],
[
"Lämmerzahl",
"C.",
""
]
] | Recently a model of metric fluctuations has been proposed which yields an effective Schr\"odinger equation for a quantum particle with a modified inertial mass, leading to a violation of the weak equivalence principle. The renormalization of the inertial mass tensor results from a local space average over the fluctuations of the metric over a fixed background metric. Here, we demonstrate that the metric fluctuations of this model lead to a further physical effect, namely to an effective decoherence of the quantum particle. We derive a quantum master equation for the particle's density matrix, discuss in detail its dissipation and decoherence properties, and estimate the corresponding decoherence time scales. By contrast to other models discussed in the literature, in the present approach the metric fluctuations give rise to a decay of the coherences in the energy representation, i. e., to a localization in energy space. |
2009.01051 | Paolo Aschieri | Paolo Aschieri, Andrzej Borowiec, Anna Pacho{\l} | Dispersion Relations in $\kappa$-Noncommutative Cosmology | 20 pages. New version: 23 pages, added 4-dim. dispersion relations
and numerical estimates | null | 10.1088/1475-7516/2021/04/025 | null | gr-qc astro-ph.HE hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study noncommutative deformations of the wave equation in curved
backgrounds and discuss the modification of the dispersion relations due to
noncommutativity combined with curvature of spacetime. Our noncommutative
differential geometry approach is based on Drinfeld twist deformation, and can
be implemented for any twist and any curved background. We discuss in detail
the Jordanian twist $-$giving $\kappa$-Minkowski spacetime in flat space$-$ in
the presence of a Friedman-Lema\^{i}tre-Robertson-Walker (FLRW) cosmological
background. We obtain a new expression for the variation of the speed of light,
depending linearly on the ratio $E_{ph}/E_{LV}$ (photon energy / Lorentz
violation scale), but also linearly on the cosmological time, the Hubble
parameter and inversely proportional to the scale factor.
| [
{
"created": "Wed, 2 Sep 2020 13:25:31 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Feb 2021 11:48:42 GMT",
"version": "v2"
}
] | 2021-04-14 | [
[
"Aschieri",
"Paolo",
""
],
[
"Borowiec",
"Andrzej",
""
],
[
"Pachoł",
"Anna",
""
]
] | We study noncommutative deformations of the wave equation in curved backgrounds and discuss the modification of the dispersion relations due to noncommutativity combined with curvature of spacetime. Our noncommutative differential geometry approach is based on Drinfeld twist deformation, and can be implemented for any twist and any curved background. We discuss in detail the Jordanian twist $-$giving $\kappa$-Minkowski spacetime in flat space$-$ in the presence of a Friedman-Lema\^{i}tre-Robertson-Walker (FLRW) cosmological background. We obtain a new expression for the variation of the speed of light, depending linearly on the ratio $E_{ph}/E_{LV}$ (photon energy / Lorentz violation scale), but also linearly on the cosmological time, the Hubble parameter and inversely proportional to the scale factor. |
1710.07597 | Paul Klinger | Piotr T. Chru\'sciel, Erwann Delay, Paul Klinger | On non-degeneracy of Riemannian Schwarzschild-anti de Sitter metrics | 40 pages, 2 figures, v2: minor updates and corrections | null | null | UWThPh-2017-30 | gr-qc hep-th math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove that the $TT$-gauge-fixed linearised Einstein operator is
non-degenerate for Riemannian Kottler ("Schwarzschild-anti de Sitter") metrics
with dimension- and topology-dependent ranges of mass parameter. We provide
evidence that this remains true for all such metrics except the spherical ones
with a critical mass.
| [
{
"created": "Fri, 20 Oct 2017 16:22:58 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Jun 2019 10:44:43 GMT",
"version": "v2"
}
] | 2019-06-27 | [
[
"Chruściel",
"Piotr T.",
""
],
[
"Delay",
"Erwann",
""
],
[
"Klinger",
"Paul",
""
]
] | We prove that the $TT$-gauge-fixed linearised Einstein operator is non-degenerate for Riemannian Kottler ("Schwarzschild-anti de Sitter") metrics with dimension- and topology-dependent ranges of mass parameter. We provide evidence that this remains true for all such metrics except the spherical ones with a critical mass. |
1007.4995 | Muhammad Sharif | M. Sharif and Wajiha Javed | Quantum Corrections for a Bardeen Regular Black Hole | 14 pages, accepted for publication in J. Korean Phys. Soc | J. Korean Phys. Soc.57:217-222, 2010 | 10.3938/jkps.57.217 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the quantum corrections to the thermodynamical
quantities (temperature and entropy) for a Bardeen charged regular black hole
by using a quantum tunneling approach over semiclassical approximations. Taking
into account the quantum effects, the semiclassical Bekenstein-Hawking
temperature and the area law are obtained, which are then used in the first law
of thermodynamics to evaluate corrections to these quantities. It is
interesting to mention here that these corrections reduce to the corresponding
corrections for the Schwarzschild black hole when the charge $e=0$.
| [
{
"created": "Tue, 27 Jul 2010 04:04:17 GMT",
"version": "v1"
}
] | 2015-05-19 | [
[
"Sharif",
"M.",
""
],
[
"Javed",
"Wajiha",
""
]
] | In this paper, we study the quantum corrections to the thermodynamical quantities (temperature and entropy) for a Bardeen charged regular black hole by using a quantum tunneling approach over semiclassical approximations. Taking into account the quantum effects, the semiclassical Bekenstein-Hawking temperature and the area law are obtained, which are then used in the first law of thermodynamics to evaluate corrections to these quantities. It is interesting to mention here that these corrections reduce to the corresponding corrections for the Schwarzschild black hole when the charge $e=0$. |
gr-qc/9706028 | Sergei Chervon | S.V.Chervon | Gravitational Field of the Early Universe: I.Non-linear Scalar Field as
the Source | 6 pages, Latex, submitted to: Grav. and Cosmol | Grav.Cosmol. 3 (1997) 145-150 | null | RGS-USU-97/01 | gr-qc | null | In this review article we consider three most important sources of the
gravitational field of the Early Universe: self-interacting scalar field,
chiral field and gauge field. The correspondence between all of them are
pointed out. More attention is payed to nonlinear scalar field source of
gravity. The progress in finding the exact solutions in inflationary universe
is reviewed. The basic idea of `fine turning of the potential' method is
discussed and computational background is presented in details. A set of new
exact solutions for standard inflationary model and conformally-flat
space-times are obtained. Special attention payed to relations between `fine
turning of the potential' and Barrow's approaches. As the example of a
synthesis of both methods new exact solution is obtained.
| [
{
"created": "Tue, 10 Jun 1997 20:50:10 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Chervon",
"S. V.",
""
]
] | In this review article we consider three most important sources of the gravitational field of the Early Universe: self-interacting scalar field, chiral field and gauge field. The correspondence between all of them are pointed out. More attention is payed to nonlinear scalar field source of gravity. The progress in finding the exact solutions in inflationary universe is reviewed. The basic idea of `fine turning of the potential' method is discussed and computational background is presented in details. A set of new exact solutions for standard inflationary model and conformally-flat space-times are obtained. Special attention payed to relations between `fine turning of the potential' and Barrow's approaches. As the example of a synthesis of both methods new exact solution is obtained. |
2106.16123 | Hao-Jui Kuan | Hao-Jui Kuan, Arthur G. Suvorov, Kostas D. Kokkotas | General-relativistic treatment of tidal $g$-mode resonances in
coalescing binaries of neutron stars. I. Theoretical framework and crust
breaking | 15 pages, 11 figures, 2 tables. Matches published version in MNRAS | null | 10.1093/mnras/stab1898 | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | During the final stages of a neutron-star binary coalescence, stellar
quasi-normal modes can become resonantly excited by tidal fields. If the strain
exerted by the excited modes exceeds the extent to which the crust can respond
linearly, localised crustal failures may occur. In this work, we re-examine
resonant $g$-mode excitations of relativistic neutron stars in the last $\sim$
10 seconds of an inspiral. We adopt realistic equations of state that pass
constraints from GW170817, include 3rd order post-Newtonian terms for the
conservation orbital motion, and employ a 2.5 post-Newtonian scheme for
gravitational back-reaction. Frequency modulations of the modes due to tidal
fields, Lorentz forces, and (slow) rotation are also considered to investigate
the maximal strain achievable by resonantly-excited $g$-modes. Depending on the
equation of state, degree of stratification, and stellar magnetic field, we
find that certain $g$-modes excitations may be able to break the crust some
seconds prior to coalescence.
| [
{
"created": "Wed, 30 Jun 2021 15:20:39 GMT",
"version": "v1"
}
] | 2021-07-14 | [
[
"Kuan",
"Hao-Jui",
""
],
[
"Suvorov",
"Arthur G.",
""
],
[
"Kokkotas",
"Kostas D.",
""
]
] | During the final stages of a neutron-star binary coalescence, stellar quasi-normal modes can become resonantly excited by tidal fields. If the strain exerted by the excited modes exceeds the extent to which the crust can respond linearly, localised crustal failures may occur. In this work, we re-examine resonant $g$-mode excitations of relativistic neutron stars in the last $\sim$ 10 seconds of an inspiral. We adopt realistic equations of state that pass constraints from GW170817, include 3rd order post-Newtonian terms for the conservation orbital motion, and employ a 2.5 post-Newtonian scheme for gravitational back-reaction. Frequency modulations of the modes due to tidal fields, Lorentz forces, and (slow) rotation are also considered to investigate the maximal strain achievable by resonantly-excited $g$-modes. Depending on the equation of state, degree of stratification, and stellar magnetic field, we find that certain $g$-modes excitations may be able to break the crust some seconds prior to coalescence. |
1805.02565 | Mauricio Bellini Prof. | Juan Ignacio Musmarra, Mariano Anabitarte, Mauricio Bellini (IFIMAR -
CONICET & UNMdP) | Inflationary expansion of the universe with variable timescale | Version accepted in Eur. Phys. J. C | null | 10.1140/epjc/s10052-018-6526-1 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore a cosmological model in which the time scale is variable with the
expansion of the universe and the effective spacetime is driven by the inflaton
field. An example is considered and their predictions are contrasted between
Planck 2018 data. We calculate the spectrum indices and the slow-rolling
parameters of the effective potential. The results are in very good agreement
with observations.
| [
{
"created": "Mon, 7 May 2018 15:17:13 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Jul 2018 15:49:02 GMT",
"version": "v2"
},
{
"created": "Mon, 10 Sep 2018 20:41:48 GMT",
"version": "v3"
},
{
"created": "Wed, 19 Sep 2018 15:22:12 GMT",
"version": "v4"
},
{
"created": "Thu, 20 Dec 2018 00:47:14 GMT",
"version": "v5"
}
] | 2019-01-30 | [
[
"Musmarra",
"Juan Ignacio",
"",
"IFIMAR -\n CONICET & UNMdP"
],
[
"Anabitarte",
"Mariano",
"",
"IFIMAR -\n CONICET & UNMdP"
],
[
"Bellini",
"Mauricio",
"",
"IFIMAR -\n CONICET & UNMdP"
]
] | We explore a cosmological model in which the time scale is variable with the expansion of the universe and the effective spacetime is driven by the inflaton field. An example is considered and their predictions are contrasted between Planck 2018 data. We calculate the spectrum indices and the slow-rolling parameters of the effective potential. The results are in very good agreement with observations. |
gr-qc/0306025 | Dr Mayeul Arminjon | Mayeul Arminjon | Point-particle limit in a scalar theory of gravitation and the weak
equivalence principle | LaTeX, 6 pages. Text of a talk given at the Rencontres de Moriond:
Gravitational Waves and Experimental Gravity, Les Arcs, France (March 22-29,
2003). Submitted to the Proceedings (J. Dumarchez, ed.) | Gravitational waves and experimental gravity, Proc. of the 38th
Rencontres de Moriond (J. Dumarchez & J. Tran Thanh Van, eds.), The Gioi,
Hanoi (2004), pp. 377-382 | null | null | gr-qc | null | A scalar theory with a preferred reference frame is summarized. To test that
theory in celestial mechanics, an "asymptotic" post-Newtonian (PN) scheme has
been developed. This associates a conceptual family of self-gravitating systems
with the given system, in order to have a true small parameter available. The
resulting equations for a weakly-self-gravitating system of extended bodies
include internal-structure effects. The internal-structure influence subsists
at the point-particle limit--a violation of the weak equivalence principle. If
one could develop an "asymptotic" approximation scheme in general relativity
also, this could plausibly be found there also, in a gauge where the PN space
metric would not be "conformally Euclidean".
| [
{
"created": "Fri, 6 Jun 2003 13:11:22 GMT",
"version": "v1"
}
] | 2007-11-19 | [
[
"Arminjon",
"Mayeul",
""
]
] | A scalar theory with a preferred reference frame is summarized. To test that theory in celestial mechanics, an "asymptotic" post-Newtonian (PN) scheme has been developed. This associates a conceptual family of self-gravitating systems with the given system, in order to have a true small parameter available. The resulting equations for a weakly-self-gravitating system of extended bodies include internal-structure effects. The internal-structure influence subsists at the point-particle limit--a violation of the weak equivalence principle. If one could develop an "asymptotic" approximation scheme in general relativity also, this could plausibly be found there also, in a gauge where the PN space metric would not be "conformally Euclidean". |
1712.09703 | Vladimir Ivashchuk | V. D. Ivashchuk and A.A. Kobtsev | Stable exponential cosmological solutions with two factor spaces in the
Einstein-Gauss-Bonnet model with a $\Lambda$-term | 37 pages, Latex, 8 figures, 42 references. One typo in eq. (3.77) is
eliminated, one phrase in Introduction and the last reference are omitted. To
be published in GERG | null | 10.1007/s10714-018-2447-4 | IGC-RUDN-18-06/02a-cor | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study $D$-dimensional Einstein-Gauss-Bonnet gravitational model including
the Gauss-Bonnet term and the cosmological term $\Lambda$. We find a class of
solutions with exponential time dependence of two scale factors, governed by
two Hubble-like parameters $H >0$ and $h$, corresponding to factor spaces of
dimensions $m >2$ and $l > 2$, respectively. These solutions contain a
fine-tuned $\Lambda = \Lambda (x, m, l, \alpha)$, which depends upon the ratio
$h/H = x$, dimensions of factor spaces $m$ and $l$, and the ratio $\alpha =
\alpha_2/\alpha_1$ of two constants ($\alpha_2$ and $\alpha_1$) of the model.
The master equation $\Lambda(x, m, l,\alpha) = \Lambda$ is equivalent to a
polynomial equation of either fourth or third order and may be solved in
radicals. The explicit solution for $m = l$ is presented in Appendix. Imposing
certain restrictions on $x$, we prove the stability of the solutions in a class
of cosmological solutions with diagonal metrics. We also consider a subclass of
solutions with small enough variation of the effective gravitational constant
$G$ and show the stability of all solutions from this subclass.
| [
{
"created": "Wed, 27 Dec 2017 23:01:01 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Apr 2018 15:32:59 GMT",
"version": "v2"
},
{
"created": "Fri, 8 Jun 2018 21:13:57 GMT",
"version": "v3"
},
{
"created": "Mon, 3 Sep 2018 17:14:55 GMT",
"version": "v4"
}
] | 2018-09-05 | [
[
"Ivashchuk",
"V. D.",
""
],
[
"Kobtsev",
"A. A.",
""
]
] | We study $D$-dimensional Einstein-Gauss-Bonnet gravitational model including the Gauss-Bonnet term and the cosmological term $\Lambda$. We find a class of solutions with exponential time dependence of two scale factors, governed by two Hubble-like parameters $H >0$ and $h$, corresponding to factor spaces of dimensions $m >2$ and $l > 2$, respectively. These solutions contain a fine-tuned $\Lambda = \Lambda (x, m, l, \alpha)$, which depends upon the ratio $h/H = x$, dimensions of factor spaces $m$ and $l$, and the ratio $\alpha = \alpha_2/\alpha_1$ of two constants ($\alpha_2$ and $\alpha_1$) of the model. The master equation $\Lambda(x, m, l,\alpha) = \Lambda$ is equivalent to a polynomial equation of either fourth or third order and may be solved in radicals. The explicit solution for $m = l$ is presented in Appendix. Imposing certain restrictions on $x$, we prove the stability of the solutions in a class of cosmological solutions with diagonal metrics. We also consider a subclass of solutions with small enough variation of the effective gravitational constant $G$ and show the stability of all solutions from this subclass. |
2011.08859 | T. Padmanabhan | T. Padmanabhan | Gravitational effective action at mesoscopic scales from the quantum
microstructure of spacetime | ver 2: minor edits; no figures; 9 pages | Phys. Letts., B 814 136109 (2021) | 10.1016/j.physletb.2021.136109 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | At mesoscopic scales, the quantum corrected field equations of gravity should
arise from extremizing, $\Omega$, the number of microscopic configurations of
pre-geometric variables consistent with a given geometry. This $\Omega$, in
turn, is the product over all events P of the density, $\rho(P)$, of
microscopic configurations associated with each event P. One would have
expected $\rho\propto\sqrt{g}$ so that $\rho d^4x$ scales as the proper volume
of a region. On the other hand, at leading order, we would expect the extremum
principle to be based on the Hilbert action, suggesting $\ln\rho\propto R$. I
show how these two apparently contradictory requirements can be reconciled by
using the functional dependence of $\sqrt{g}$ on curvature, in the Riemann
normal coordinates (RNC), and coarse-graining over Planck scales. This leads to
the density of microscopic configurations to be $\rho = \Delta^{-1} =
\sqrt{g}_{RNC}$ where $\Delta$ is the coarse grained Van-Vleck determinant. The
approach also provides: (a) systematic way of computing QG corrections to field
equations and (b) a direct link between the effective action for gravity and
the kinetic theory of the spacetime fluid.
| [
{
"created": "Tue, 17 Nov 2020 19:00:01 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Feb 2021 14:46:58 GMT",
"version": "v2"
}
] | 2021-02-08 | [
[
"Padmanabhan",
"T.",
""
]
] | At mesoscopic scales, the quantum corrected field equations of gravity should arise from extremizing, $\Omega$, the number of microscopic configurations of pre-geometric variables consistent with a given geometry. This $\Omega$, in turn, is the product over all events P of the density, $\rho(P)$, of microscopic configurations associated with each event P. One would have expected $\rho\propto\sqrt{g}$ so that $\rho d^4x$ scales as the proper volume of a region. On the other hand, at leading order, we would expect the extremum principle to be based on the Hilbert action, suggesting $\ln\rho\propto R$. I show how these two apparently contradictory requirements can be reconciled by using the functional dependence of $\sqrt{g}$ on curvature, in the Riemann normal coordinates (RNC), and coarse-graining over Planck scales. This leads to the density of microscopic configurations to be $\rho = \Delta^{-1} = \sqrt{g}_{RNC}$ where $\Delta$ is the coarse grained Van-Vleck determinant. The approach also provides: (a) systematic way of computing QG corrections to field equations and (b) a direct link between the effective action for gravity and the kinetic theory of the spacetime fluid. |
gr-qc/0301062 | Ulises Nucamendi | Ulises Nucamendi and Marcelo Salgado | Scalar hairy black holes and solitons in asymptotically flat spacetimes | 7 pages, 10 postscript figures, file tex, new postscript figs. and
references added, stability analysis revisited | Phys.Rev. D68 (2003) 044026 | 10.1103/PhysRevD.68.044026 | null | gr-qc hep-th | null | A numerical analysis shows that a class of scalar-tensor theories of gravity
with a scalar field minimally and nonminimally coupled to the curvature allows
static and spherically symmetric black hole solutions with scalar-field hair in
asymptotically flat spacetimes. In the limit when the horizon radius of the
black hole tends to zero, regular scalar solitons are found. The asymptotically
flat solutions are obtained provided that the scalar potential $V(\phi)$ of the
theory is not positive semidefinite and such that its local minimum is also a
zero of the potential, the scalar field settling asymptotically at that
minimum. The configurations for the minimal coupling case, although unstable
under spherically symmetric linear perturbations, are regular and thus can
serve as counterexamples to the no-scalar-hair conjecture. For the nonminimal
coupling case, the stability will be analyzed in a forthcoming paper.
| [
{
"created": "Fri, 17 Jan 2003 04:12:43 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Mar 2003 00:47:24 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Nucamendi",
"Ulises",
""
],
[
"Salgado",
"Marcelo",
""
]
] | A numerical analysis shows that a class of scalar-tensor theories of gravity with a scalar field minimally and nonminimally coupled to the curvature allows static and spherically symmetric black hole solutions with scalar-field hair in asymptotically flat spacetimes. In the limit when the horizon radius of the black hole tends to zero, regular scalar solitons are found. The asymptotically flat solutions are obtained provided that the scalar potential $V(\phi)$ of the theory is not positive semidefinite and such that its local minimum is also a zero of the potential, the scalar field settling asymptotically at that minimum. The configurations for the minimal coupling case, although unstable under spherically symmetric linear perturbations, are regular and thus can serve as counterexamples to the no-scalar-hair conjecture. For the nonminimal coupling case, the stability will be analyzed in a forthcoming paper. |
1408.4531 | Hamed Pejhan | Hamed Pejhan and Surena Rahbardehghan | Examining a covariant and renormalizable quantum field theory in de
Sitter space by studying "black hole radiation" | 8 pages, published version | Int. J. Mod. Phys. A 31, 1650052 (2016) | 10.1142/S0217751X16500524 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Respecting that any consistent quantum field theory in curved space-time must
include black hole radiation, in this paper, we examine the Krein-Gupta-Bleuler
(KGB) formalism as an inevitable quantization scheme in order to follow the
guideline of the covariance of minimally coupled massless scalar field and
linear gravity on de Sitter (dS) background in the sense of
Wightman-G\"{a}rding approach, by investigating thermodynamical aspects of
black holes. The formalism is interestingly free of pathological large distance
behavior. In this construction, also, no infinite term appears in the
calculation of expectation values of the energy-momentum tensor (we have an
automatic and covariant renormalization) which results in the vacuum energy of
the free field vanishes. However, the existence of an effective potential
barrier, intrinsically created by black holes gravitational field, gives a
Casimir-type contribution to the vacuum expectation value of the
energy-momentum tensor. On this basis, by evaluating the Casimir
energy-momentum tensor for a conformally coupled massless scalar field in the
vicinity of a non-rotating black hole event horizon through the KGB
quantization, in this work, we explicitly prove that the hole produces
black-body radiation which its temperature exactly coincides with the result
obtained by Hawking for black hole radiation.
| [
{
"created": "Wed, 20 Aug 2014 06:06:06 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Aug 2014 10:56:04 GMT",
"version": "v2"
},
{
"created": "Mon, 5 Jan 2015 13:55:22 GMT",
"version": "v3"
},
{
"created": "Wed, 7 Jan 2015 09:29:50 GMT",
"version": "v4"
},
{
"created": "Tue, 14 Jul 2015 12:25:54 GMT",
"version": "v5"
},
{
"created": "Mon, 2 Nov 2015 14:38:23 GMT",
"version": "v6"
},
{
"created": "Tue, 15 Mar 2016 12:24:50 GMT",
"version": "v7"
}
] | 2018-08-14 | [
[
"Pejhan",
"Hamed",
""
],
[
"Rahbardehghan",
"Surena",
""
]
] | Respecting that any consistent quantum field theory in curved space-time must include black hole radiation, in this paper, we examine the Krein-Gupta-Bleuler (KGB) formalism as an inevitable quantization scheme in order to follow the guideline of the covariance of minimally coupled massless scalar field and linear gravity on de Sitter (dS) background in the sense of Wightman-G\"{a}rding approach, by investigating thermodynamical aspects of black holes. The formalism is interestingly free of pathological large distance behavior. In this construction, also, no infinite term appears in the calculation of expectation values of the energy-momentum tensor (we have an automatic and covariant renormalization) which results in the vacuum energy of the free field vanishes. However, the existence of an effective potential barrier, intrinsically created by black holes gravitational field, gives a Casimir-type contribution to the vacuum expectation value of the energy-momentum tensor. On this basis, by evaluating the Casimir energy-momentum tensor for a conformally coupled massless scalar field in the vicinity of a non-rotating black hole event horizon through the KGB quantization, in this work, we explicitly prove that the hole produces black-body radiation which its temperature exactly coincides with the result obtained by Hawking for black hole radiation. |
2209.06938 | Eduardo Velasco-Aja | Eduardo Velasco-Aja and Jesus Anero | Quantum corrections to Einstein's equations | 39 pages | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In this master thesis, the Frobenius power series method is used to find
spherically symmetric and static vacuum solutions to quadratic and cubic
gravitational actions, representing quantum corrections to the Einstein-Hilbert
action. After a motivation to the topic and an introduction, the power series
solutions are presented. After recovering the results for the quadratic action
of Stelle and collaborators, we found that when the Weyl cubic operator is
present, the (2,2) family of solutions is still present while the
Schwarzschid-de Sitter-like (1,-1) is not.
| [
{
"created": "Wed, 14 Sep 2022 21:20:43 GMT",
"version": "v1"
}
] | 2022-09-16 | [
[
"Velasco-Aja",
"Eduardo",
""
],
[
"Anero",
"Jesus",
""
]
] | In this master thesis, the Frobenius power series method is used to find spherically symmetric and static vacuum solutions to quadratic and cubic gravitational actions, representing quantum corrections to the Einstein-Hilbert action. After a motivation to the topic and an introduction, the power series solutions are presented. After recovering the results for the quadratic action of Stelle and collaborators, we found that when the Weyl cubic operator is present, the (2,2) family of solutions is still present while the Schwarzschid-de Sitter-like (1,-1) is not. |
2309.06002 | Ioannis Soranidis | Sebastian Murk and Ioannis Soranidis | Kinematic and energy properties of dynamical regular black holes | 13 pages, 6 figures. Published version. Comments welcome! | Phys. Rev. D 108, 124007 (2023) | 10.1103/PhysRevD.108.124007 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Nonsingular black holes have received much attention in recent years as they
provide an opportunity to avoid the singularities inherent to the mathematical
black holes predicted by general relativity. Based on the assumption that
semiclassical physics remains valid in the vicinity of their horizons, we
derive kinematic properties of dynamically evolving spherically symmetric
regular black holes. We review the Hawking--Ellis classification of their
associated energy-momentum tensors and examine the status of the null energy
condition in the vicinity of their horizons as well as their interior. In
addition, we analyze the trajectory of a moving observer, find that the
horizons can be crossed on an ingoing geodesic, and thus entering and exiting
the supposedly trapped spacetime region is possible. We outline the
ramifications of this result for the information loss problem and black hole
thermodynamics. Throughout the article, we illustrate relevant features based
on the dynamical generalization of the regular black hole model proposed in J.
High Energy Phys. 09, 118 (2022) and elucidate connections to the only
self-consistent dynamical physical black hole solutions in spherical symmetry.
| [
{
"created": "Tue, 12 Sep 2023 06:58:25 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Dec 2023 05:17:44 GMT",
"version": "v2"
}
] | 2023-12-07 | [
[
"Murk",
"Sebastian",
""
],
[
"Soranidis",
"Ioannis",
""
]
] | Nonsingular black holes have received much attention in recent years as they provide an opportunity to avoid the singularities inherent to the mathematical black holes predicted by general relativity. Based on the assumption that semiclassical physics remains valid in the vicinity of their horizons, we derive kinematic properties of dynamically evolving spherically symmetric regular black holes. We review the Hawking--Ellis classification of their associated energy-momentum tensors and examine the status of the null energy condition in the vicinity of their horizons as well as their interior. In addition, we analyze the trajectory of a moving observer, find that the horizons can be crossed on an ingoing geodesic, and thus entering and exiting the supposedly trapped spacetime region is possible. We outline the ramifications of this result for the information loss problem and black hole thermodynamics. Throughout the article, we illustrate relevant features based on the dynamical generalization of the regular black hole model proposed in J. High Energy Phys. 09, 118 (2022) and elucidate connections to the only self-consistent dynamical physical black hole solutions in spherical symmetry. |
1610.08357 | Athanasios Bakopoulos | Athanasios Bakopoulos | Gravitoelectromagnetism: Basic principles, novel approaches and their
application to Electromagnetism | 67 pages, Master Thesis | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work is focused on the theory of Gravitoelectromagnetism (GEM). In the
first part of this work we present a brief review of gravitoelectromagnetism,
we locate and discuss all the problems which appear in this approach. We also
try to avoid these problems by proposing new approaches in which we use the
additional degrees of freedom of the gravitational field. In the second part of
this work, we review our previous work regarding the construction of a
tensorial theory, using the formalism of General Relativity, which aims to
describe the true electromagnetism. We also extend this theory in order to make
it more realistic. Finally in the third part of this work, we investigate the
existence of gravitational invariants similar to the electromagnetic ones.
| [
{
"created": "Tue, 25 Oct 2016 15:46:01 GMT",
"version": "v1"
}
] | 2016-10-27 | [
[
"Bakopoulos",
"Athanasios",
""
]
] | This work is focused on the theory of Gravitoelectromagnetism (GEM). In the first part of this work we present a brief review of gravitoelectromagnetism, we locate and discuss all the problems which appear in this approach. We also try to avoid these problems by proposing new approaches in which we use the additional degrees of freedom of the gravitational field. In the second part of this work, we review our previous work regarding the construction of a tensorial theory, using the formalism of General Relativity, which aims to describe the true electromagnetism. We also extend this theory in order to make it more realistic. Finally in the third part of this work, we investigate the existence of gravitational invariants similar to the electromagnetic ones. |
gr-qc/0605155 | Scott Pollack | Scott E Pollack and Robin Tuck Stebbins | A Demonstration of LISA Laser Communication | minor corrections found in the CQG version | Class.Quant.Grav.23:4201-4213,2006 | 10.1088/0264-9381/23/12/015 | null | gr-qc | null | Over the past few years questions have been raised concerning the use of
laser communications links between sciencecraft to transmit phase information
crucial to the reduction of laser frequency noise in the LISA science
measurement. The concern is that applying medium frequency phase modulations to
the laser carrier could compromise the phase stability of the LISA fringe
signal. We have modified the table-top interferometer presented in a previous
article by applying phase modulations to the laser beams in order to evaluate
the effects of such modulations on the LISA science fringe signal. We have
demonstrated that the phase resolution of the science signal is not degraded by
the presence of medium frequency phase modulations.
| [
{
"created": "Wed, 31 May 2006 19:38:55 GMT",
"version": "v1"
}
] | 2010-11-05 | [
[
"Pollack",
"Scott E",
""
],
[
"Stebbins",
"Robin Tuck",
""
]
] | Over the past few years questions have been raised concerning the use of laser communications links between sciencecraft to transmit phase information crucial to the reduction of laser frequency noise in the LISA science measurement. The concern is that applying medium frequency phase modulations to the laser carrier could compromise the phase stability of the LISA fringe signal. We have modified the table-top interferometer presented in a previous article by applying phase modulations to the laser beams in order to evaluate the effects of such modulations on the LISA science fringe signal. We have demonstrated that the phase resolution of the science signal is not degraded by the presence of medium frequency phase modulations. |
gr-qc/0104101 | Will Loinaz | J. B. Hertzberg, S. R. Bickman, M. T. Hummon, D. Krause, S. K. Peck
and L. R. Hunter (Amherst College) | Measurement of the Relativistic Potential Difference Across a Rotating
Dielectric Cylinder | 22 pages, 5 figures; to be published in the American Journal of
Physics | Am.J.Phys. 69 (2001) 648-654 | 10.1119/1.1362695 | null | gr-qc hep-ex | null | According to the Special Theory of Relativity, a rotating magnetic dielectric
cylinder in an axial magnetic field should exhibit a contribution to the radial
electric potential that is associated with the motion of the material's
magnetic dipoles. In 1913 Wilson and Wilson reported a measurement of the
potential difference across a magnetic dielectric constructed from wax and
steel balls. Their measurement has long been regarded as a verification of this
prediction. In 1995 Pelligrini and Swift questioned the theoretical basis of
experiment. In particular, they pointed out that it is not obvious that a
rotating medium may be treated as if each point in the medium is locally
inertial. They calculated the effect in the rotating frame and predicted a
potential different from both Wilson's theory and experiment. Subsequent
analysis of the experiment suggests that Wilson's experiment does not
distinguish between the two predictions due to the fact that their composite
steel-wax cylinder is conductive in the regions of magnetization. We report
measurements of the radial voltage difference across various rotating
dielectric cylinders, including a homogeneous magnetic material (YIG), to
unambiguously test the competing calculations. Our results are compatible with
the traditional treatment of the effect using a co-moving locally inertial
reference frame, and are incompatible with the predictions based on the model
of Pelligrini and Swift.
| [
{
"created": "Mon, 30 Apr 2001 18:03:55 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Hertzberg",
"J. B.",
"",
"Amherst College"
],
[
"Bickman",
"S. R.",
"",
"Amherst College"
],
[
"Hummon",
"M. T.",
"",
"Amherst College"
],
[
"Krause",
"D.",
"",
"Amherst College"
],
[
"Peck",
"S. K.",
"",
"Amherst College"
],
[
"Hunter",
"L. R.",
"",
"Amherst College"
]
] | According to the Special Theory of Relativity, a rotating magnetic dielectric cylinder in an axial magnetic field should exhibit a contribution to the radial electric potential that is associated with the motion of the material's magnetic dipoles. In 1913 Wilson and Wilson reported a measurement of the potential difference across a magnetic dielectric constructed from wax and steel balls. Their measurement has long been regarded as a verification of this prediction. In 1995 Pelligrini and Swift questioned the theoretical basis of experiment. In particular, they pointed out that it is not obvious that a rotating medium may be treated as if each point in the medium is locally inertial. They calculated the effect in the rotating frame and predicted a potential different from both Wilson's theory and experiment. Subsequent analysis of the experiment suggests that Wilson's experiment does not distinguish between the two predictions due to the fact that their composite steel-wax cylinder is conductive in the regions of magnetization. We report measurements of the radial voltage difference across various rotating dielectric cylinders, including a homogeneous magnetic material (YIG), to unambiguously test the competing calculations. Our results are compatible with the traditional treatment of the effect using a co-moving locally inertial reference frame, and are incompatible with the predictions based on the model of Pelligrini and Swift. |
1309.5774 | M. Hossein Dehghani | A. Sheykhi, M. H. Dehghani and S. E. Hosseini | Emergence of spacetime dynamics in entropy corrected and braneworld
models | 17 pages, Latex. arXiv admin note: text overlap with arXiv:1304.3054 | JCAP, 04 (2013) 038 | 10.1088/1475-7516/2013/04/038 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A very interesting new proposal on the origin of the cosmic expansion was
recently suggested by Padmanabhan [arXiv:1206.4916]. He argued that the
difference between the surface degrees of freedom and the bulk degrees of
freedom in a region of space drives the accelerated expansion of the universe,
as well as the standard Friedmann equation through relation $% \triangle
V=\triangle t(N_{\mathrm{sur}}-N_{\mathrm{bulk}})$. In this paper, we first
present the general expression for the number of degrees of freedom on the
holographic surface, $N_{\mathrm{sur}}$, using the general entropy corrected
formula $S=\frac{A}{4 L_{p}^2}+s(A)$. Then, as two example, by applying the
Padmanabhan's idea we extract the corresponding Friedmann equations in the
presence of power-law and logarithmic correction terms in the entropy. We also
extend the study to RS II and DGP branworld models and derive successfully the
correct form of the Friedmann equations in these theories. Our study further
supports the viability of Padmanabhan's proposal.
| [
{
"created": "Mon, 23 Sep 2013 11:37:33 GMT",
"version": "v1"
}
] | 2013-09-24 | [
[
"Sheykhi",
"A.",
""
],
[
"Dehghani",
"M. H.",
""
],
[
"Hosseini",
"S. E.",
""
]
] | A very interesting new proposal on the origin of the cosmic expansion was recently suggested by Padmanabhan [arXiv:1206.4916]. He argued that the difference between the surface degrees of freedom and the bulk degrees of freedom in a region of space drives the accelerated expansion of the universe, as well as the standard Friedmann equation through relation $% \triangle V=\triangle t(N_{\mathrm{sur}}-N_{\mathrm{bulk}})$. In this paper, we first present the general expression for the number of degrees of freedom on the holographic surface, $N_{\mathrm{sur}}$, using the general entropy corrected formula $S=\frac{A}{4 L_{p}^2}+s(A)$. Then, as two example, by applying the Padmanabhan's idea we extract the corresponding Friedmann equations in the presence of power-law and logarithmic correction terms in the entropy. We also extend the study to RS II and DGP branworld models and derive successfully the correct form of the Friedmann equations in these theories. Our study further supports the viability of Padmanabhan's proposal. |
1609.01540 | David Viennot | David Viennot, Olivia Moro | Adiabatic transport of qubits around a black hole | null | Class. Quant. Gravity, 34, 055005 (2017) | 10.1088/1361-6382/aa5b5c | null | gr-qc math-ph math.MP quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider localized qubits evolving around a black hole following a quantum
adiabatic dynamics. We develop a geometric structure (based on fibre bundles)
permitting to describe the quantum states of a qubit and the spacetime geometry
in a single framework. The quantum decoherence induced by the black hole on the
qubit is analysed in this framework (the role of the dynamical and geometric
phases in this decoherence is treated), especially for the quantum
teleportation protocol when one qubit falls to the event horizon. A simple
formula to compute the fidelity of the teleportation is derived. The case of a
Schwarzschild black hole is analysed.
| [
{
"created": "Tue, 6 Sep 2016 13:14:14 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Jan 2017 10:01:43 GMT",
"version": "v2"
}
] | 2017-02-13 | [
[
"Viennot",
"David",
""
],
[
"Moro",
"Olivia",
""
]
] | We consider localized qubits evolving around a black hole following a quantum adiabatic dynamics. We develop a geometric structure (based on fibre bundles) permitting to describe the quantum states of a qubit and the spacetime geometry in a single framework. The quantum decoherence induced by the black hole on the qubit is analysed in this framework (the role of the dynamical and geometric phases in this decoherence is treated), especially for the quantum teleportation protocol when one qubit falls to the event horizon. A simple formula to compute the fidelity of the teleportation is derived. The case of a Schwarzschild black hole is analysed. |
gr-qc/0309076 | Karasik David | D. Karasik, C. Sahabandu, P. Suranyi and L. C. R. Wijewardhana | Small Black Holes in Randall-Sundrum type I Scenario | Version published at Phys. Rev. D69:064022 (2004) | Phys.Rev. D69 (2004) 064022 | 10.1103/PhysRevD.69.064022 | null | gr-qc hep-th | null | An approximation method to study the properties of a small black hole located
on the TeV brane in the Randall-Sundrum type I scenario is presented. The
method enables us to find the form of the metric close to the matter
distribution when its asymptotic form is given. The short range solution is
found as an expansion in the ratio between the Schwarzschild radius of the
black hole and the curvature length of the bulk. Long range properties are
introduced using the linearized gravity solution as an asymptotic boundary
condition. The solution is found up to first order. It is valid in the region
close to the horizon but is not valid on the horizon. The regularity of the
horizon is still under study.
| [
{
"created": "Tue, 16 Sep 2003 16:23:29 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Sep 2003 20:28:29 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Mar 2004 16:38:40 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Karasik",
"D.",
""
],
[
"Sahabandu",
"C.",
""
],
[
"Suranyi",
"P.",
""
],
[
"Wijewardhana",
"L. C. R.",
""
]
] | An approximation method to study the properties of a small black hole located on the TeV brane in the Randall-Sundrum type I scenario is presented. The method enables us to find the form of the metric close to the matter distribution when its asymptotic form is given. The short range solution is found as an expansion in the ratio between the Schwarzschild radius of the black hole and the curvature length of the bulk. Long range properties are introduced using the linearized gravity solution as an asymptotic boundary condition. The solution is found up to first order. It is valid in the region close to the horizon but is not valid on the horizon. The regularity of the horizon is still under study. |
1603.03723 | Luciano Burderi Prof. | Luciano Burderi, Tiziana Di Salvo, Rosario Iaria | Quantum clock: A critical discussion on spacetime | 10 pages, published in Physical Review D | Physical Review D 93, 064017 (2016) | 10.1103/PhysRevD.93.064017 | null | gr-qc astro-ph.HE hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We critically discuss the measure of very short time intervals. By means of a
Gedankenexperiment, we describe an ideal clock based on the occurrence of
completely random events. Many previous thought experiments have suggested
fundamental Planck-scale limits on measurements of distance and time. Here we
present a new type of thought experiment, based on a different type of clock,
that provide further support for the existence of such limits. We show that the
minimum time interval $\Delta t$ that this clock can measure scales as the
inverse of its size $\Delta r$. This implies an uncertainty relation between
space and time: $\Delta r$ $\Delta t$ $> G \hbar / c^4$; where G, $\hbar$ and c
are the gravitational constant, the reduced Planck constant, and the speed of
light, respectively. We outline and briefly discuss the implications of this
uncertainty conjecture.
| [
{
"created": "Fri, 11 Mar 2016 18:58:43 GMT",
"version": "v1"
}
] | 2016-03-14 | [
[
"Burderi",
"Luciano",
""
],
[
"Di Salvo",
"Tiziana",
""
],
[
"Iaria",
"Rosario",
""
]
] | We critically discuss the measure of very short time intervals. By means of a Gedankenexperiment, we describe an ideal clock based on the occurrence of completely random events. Many previous thought experiments have suggested fundamental Planck-scale limits on measurements of distance and time. Here we present a new type of thought experiment, based on a different type of clock, that provide further support for the existence of such limits. We show that the minimum time interval $\Delta t$ that this clock can measure scales as the inverse of its size $\Delta r$. This implies an uncertainty relation between space and time: $\Delta r$ $\Delta t$ $> G \hbar / c^4$; where G, $\hbar$ and c are the gravitational constant, the reduced Planck constant, and the speed of light, respectively. We outline and briefly discuss the implications of this uncertainty conjecture. |
1104.0356 | P.A. Gonzalez | Ram\'on Becar and P. A. Gonz\'alez | Hawking Radiation for Scalar and Dirac Fields in Five Dimensional
Dilatonic Black Hole via Anomalies | 10 pages | null | 10.1142/S0218271812500307 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study massive scalar fields and Dirac fields propagating in a five
dimensional dilatonic black hole background. We expose that for both fields the
physics can be describe by a two dimensional theory, near the horizon. Then, in
this limit, by applying the covariant anomalies method we find the Hawking flux
by restoring the gauge invariance and the general coordinate covariance, which
coincides with the flux obtained from integrating the Planck distribution for
fermions.
| [
{
"created": "Sun, 3 Apr 2011 05:29:50 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Sep 2011 12:57:41 GMT",
"version": "v2"
},
{
"created": "Sun, 22 Jan 2012 14:30:30 GMT",
"version": "v3"
}
] | 2015-05-27 | [
[
"Becar",
"Ramón",
""
],
[
"González",
"P. A.",
""
]
] | We study massive scalar fields and Dirac fields propagating in a five dimensional dilatonic black hole background. We expose that for both fields the physics can be describe by a two dimensional theory, near the horizon. Then, in this limit, by applying the covariant anomalies method we find the Hawking flux by restoring the gauge invariance and the general coordinate covariance, which coincides with the flux obtained from integrating the Planck distribution for fermions. |
gr-qc/0305014 | David Garfinkle | David Garfinkle, Robert Mann, Chris Vuille | Critical collapse of a massive vector field | 7 pages, 4 figures | Phys.Rev. D68 (2003) 064015 | 10.1103/PhysRevD.68.064015 | null | gr-qc | null | We perform numerical simulations of the critical gravitational collapse of a
massive vector field. The result is that there are two critical solutions. One
is equivalent to the Choptuik critical solution for a massless scalar field.
The other is periodic.
| [
{
"created": "Sat, 3 May 2003 12:24:27 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Garfinkle",
"David",
""
],
[
"Mann",
"Robert",
""
],
[
"Vuille",
"Chris",
""
]
] | We perform numerical simulations of the critical gravitational collapse of a massive vector field. The result is that there are two critical solutions. One is equivalent to the Choptuik critical solution for a massless scalar field. The other is periodic. |
1605.02729 | Richard Woodard | D. J. Brooker (Florida), N. C. Tsamis (Crete) and R. P. Woodard
(Florida) | The Effect of Features on the Functional Form of the Scalar Power
Spectrum | 27 pages, 14 figures, uses LaTeX2e; version 2 contains an expanded
section 4 which explains how to compute the phase of the mode function so
that the propagator and non-Gaussianity can be derived | Phys. Rev. D 94, 044020 (2016) | 10.1103/PhysRevD.94.044020 | UFIFT-QG-16-02 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study how the scalar power spectrum of single-scalar inflation depends
functionally on models with features which have been proposed to explain
anomalies in the data. We exploit a new formalism based on evolving the
norm-squared of the scalar mode functions, rather than the mode functions
themselves.
| [
{
"created": "Mon, 9 May 2016 15:53:48 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Sep 2016 00:43:43 GMT",
"version": "v2"
}
] | 2016-09-27 | [
[
"Brooker",
"D. J.",
"",
"Florida"
],
[
"Tsamis",
"N. C.",
"",
"Crete"
],
[
"Woodard",
"R. P.",
"",
"Florida"
]
] | We study how the scalar power spectrum of single-scalar inflation depends functionally on models with features which have been proposed to explain anomalies in the data. We exploit a new formalism based on evolving the norm-squared of the scalar mode functions, rather than the mode functions themselves. |
1711.07087 | Vedad Pasic Dr | Vedad Pasic and Elvis Barakovic | Axial torsion waves in metric-affine gravity | 6 pages. Proceedings of the MG14 Meeting on General Relativity,
University of Rome "La Sapienza", Italy, 12 - 18 July 2015. Edited by:
Massimo Bianchi (Universit\`a degli Studi di Roma "Tor Vergata", Italy),
Robert T Jantzen (Villanova University, USA), Remo Ruffini (International
Center for Relativistic Astrophysics Network (ICRANet), Italy and University
of Rome "La Sapienza", Italy) | null | 10.1142/9789813226609_0080 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct new explicit vacuum solutions of quadratic metric-affine
gravity. The approach of metric-affine gravity in using an independent affine
connection produces a theory with 10+64 unknowns, which implies admitting
torsion and possible nonmetricity. Our spacetimes are generalisations of
classical pp-waves, four-dimensional Lorentzian spacetimes which admit a
nonvanishing parallel spinor field. We generalize this definition to metric
compatible spacetimes with pp-metric and purely axial torsion. It has been
suggested that one can interpret that the axial component of torsion as the
Hodge dual of the electromagnetic vector potential. We compare these solutions
with our previous results and other solutions of classical models describing
the interaction of gravitational and neutrino fields.
| [
{
"created": "Sun, 19 Nov 2017 21:42:52 GMT",
"version": "v1"
}
] | 2019-02-27 | [
[
"Pasic",
"Vedad",
""
],
[
"Barakovic",
"Elvis",
""
]
] | We construct new explicit vacuum solutions of quadratic metric-affine gravity. The approach of metric-affine gravity in using an independent affine connection produces a theory with 10+64 unknowns, which implies admitting torsion and possible nonmetricity. Our spacetimes are generalisations of classical pp-waves, four-dimensional Lorentzian spacetimes which admit a nonvanishing parallel spinor field. We generalize this definition to metric compatible spacetimes with pp-metric and purely axial torsion. It has been suggested that one can interpret that the axial component of torsion as the Hodge dual of the electromagnetic vector potential. We compare these solutions with our previous results and other solutions of classical models describing the interaction of gravitational and neutrino fields. |
2305.18521 | Michael Florian Wondrak | Michael F. Wondrak, Walter D. van Suijlekom, Heino Falcke | Gravitational Pair Production and Black Hole Evaporation | 11 pages, 2 figures. To appear in Physical Review Letters | Phys. Rev. Lett. 130 (2023) 221502 | 10.1103/PhysRevLett.130.221502 | null | gr-qc astro-ph.HE hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new avenue to black hole evaporation using a heat-kernel
approach analogous as for the Schwinger effect. Applying this method to an
uncharged massless scalar field in a Schwarzschild spacetime, we show that
spacetime curvature takes a similar role as the electric field strength in the
Schwinger effect. We interpret our results as local pair production in a
gravitational field and derive a radial production profile. The resulting
emission peaks near the unstable photon orbit. Comparing the particle number
and energy flux to the Hawking case, we find both effects to be of similar
order. However, our pair production mechanism itself does not explicitly make
use of the presence of a black hole event horizon.
| [
{
"created": "Mon, 29 May 2023 18:00:02 GMT",
"version": "v1"
}
] | 2023-06-05 | [
[
"Wondrak",
"Michael F.",
""
],
[
"van Suijlekom",
"Walter D.",
""
],
[
"Falcke",
"Heino",
""
]
] | We present a new avenue to black hole evaporation using a heat-kernel approach analogous as for the Schwinger effect. Applying this method to an uncharged massless scalar field in a Schwarzschild spacetime, we show that spacetime curvature takes a similar role as the electric field strength in the Schwinger effect. We interpret our results as local pair production in a gravitational field and derive a radial production profile. The resulting emission peaks near the unstable photon orbit. Comparing the particle number and energy flux to the Hawking case, we find both effects to be of similar order. However, our pair production mechanism itself does not explicitly make use of the presence of a black hole event horizon. |
1709.10155 | Lior M. Burko | Lior M. Burko and Gaurav Khanna | Linearized Stability of Extreme Black Holes | 4 pages, 4 figures | Phys. Rev. D 97, 061502 (2018) | 10.1103/PhysRevD.97.061502 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Extreme black holes have been argued to be unstable, in the sense that under
linearized gravitational perturbations of the extreme Kerr spacetime the Weyl
scalar $\psi_4$ blows up along their event horizons at very late advanced
times. We show numerically, by solving the Teukolsky equation in 2+1D, that all
algebraically-independent curvature scalar polynomials approach limits that
exist when advanced time along the event horizon approaches infinity.
Therefore, the horizons of extreme black holes are stable against linearized
gravitational perturbations. We argue that the divergence of $\psi_4$ is a
consequence of the choice of a fixed tetrad, and that in a suitable dynamical
tetrad all Weyl scalars, including $\psi_4$, approach their background extreme
Kerr values. We make similar conclusions also for the case of scalar field
perturbations of extreme Kerr.
| [
{
"created": "Thu, 28 Sep 2017 20:12:52 GMT",
"version": "v1"
}
] | 2018-04-04 | [
[
"Burko",
"Lior M.",
""
],
[
"Khanna",
"Gaurav",
""
]
] | Extreme black holes have been argued to be unstable, in the sense that under linearized gravitational perturbations of the extreme Kerr spacetime the Weyl scalar $\psi_4$ blows up along their event horizons at very late advanced times. We show numerically, by solving the Teukolsky equation in 2+1D, that all algebraically-independent curvature scalar polynomials approach limits that exist when advanced time along the event horizon approaches infinity. Therefore, the horizons of extreme black holes are stable against linearized gravitational perturbations. We argue that the divergence of $\psi_4$ is a consequence of the choice of a fixed tetrad, and that in a suitable dynamical tetrad all Weyl scalars, including $\psi_4$, approach their background extreme Kerr values. We make similar conclusions also for the case of scalar field perturbations of extreme Kerr. |
1911.10296 | Euclides Silva | L.A. Lessa, J.E.G. Silva, R.V. Maluf, C.A.S. Almeida | Modified black hole solution with a background Kalb-Ramond field | 9 pages. Published version | Eur. Phys. J. C 80, 335 (2020) | 10.1140/epjc/s10052-020-7902-1 | null | gr-qc hep-th | http://creativecommons.org/publicdomain/zero/1.0/ | We study the gravitation effects on a static and spherically symmetric
spacetime due to the vacuum expectation value (VEV) of a Kalb-Ramond field. The
Kalb-Ramond VEV is a background tensor field which produces a local Lorentz
symmetry breaking (LSB) of spacetime. Considering a non-minimal coupling
between the Kalb-Ramond (VEV) and the Ricci tensor, we obtain an exact
parameter-dependent power-law modified black hole. For a particular choice of
the LSB parameter, the Lorentz violation produces a solution similar to the
Reissner-Nordstrom, despite the absence of charge. The near-horizon geometry is
modified by including a new inner horizon and shifting the Schwarzschild
horizon. Asymptotically, the usual Minkowski spacetime with a background tensor
field is recovered. The vacuum configurations are studied considering the
energy conditions and the Lorentz violating source properties. By means of the
mercury perihelion test, an upper bound to the local Lorentz violation (LV) is
obtained, and its corresponding effects on the black hole temperature is
investigated.
| [
{
"created": "Sat, 23 Nov 2019 01:35:26 GMT",
"version": "v1"
},
{
"created": "Sat, 30 May 2020 01:15:03 GMT",
"version": "v2"
}
] | 2020-06-02 | [
[
"Lessa",
"L. A.",
""
],
[
"Silva",
"J. E. G.",
""
],
[
"Maluf",
"R. V.",
""
],
[
"Almeida",
"C. A. S.",
""
]
] | We study the gravitation effects on a static and spherically symmetric spacetime due to the vacuum expectation value (VEV) of a Kalb-Ramond field. The Kalb-Ramond VEV is a background tensor field which produces a local Lorentz symmetry breaking (LSB) of spacetime. Considering a non-minimal coupling between the Kalb-Ramond (VEV) and the Ricci tensor, we obtain an exact parameter-dependent power-law modified black hole. For a particular choice of the LSB parameter, the Lorentz violation produces a solution similar to the Reissner-Nordstrom, despite the absence of charge. The near-horizon geometry is modified by including a new inner horizon and shifting the Schwarzschild horizon. Asymptotically, the usual Minkowski spacetime with a background tensor field is recovered. The vacuum configurations are studied considering the energy conditions and the Lorentz violating source properties. By means of the mercury perihelion test, an upper bound to the local Lorentz violation (LV) is obtained, and its corresponding effects on the black hole temperature is investigated. |
1905.03272 | Bo Wang | Bo Wang, Yang Zhang | Second-order cosmological perturbations. IV. Produced by scalar-tensor
and tensor-tensor couplings during the radiation dominated stage | 79 pages, 2 figures | Phys. Rev. D 99, 123008 (2019) | 10.1103/PhysRevD.99.123008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We continue to study the 2nd-order cosmological perturbations in synchronous
coordinates in the framework of the general relativity (GR) during the
radiation dominated (RD) stage, and to focus on the scalar-tensor and
tensor-tensor couplings. The 1st-order curl velocity and the associated
1st-order vector metric perturbations are assumed to be vanishing. By
analytically solving the 2nd-order Einstein equation and the energy-momentum
conservation equations, we obtain the 2nd-order formal solutions (in the
integral form) of all the metric perturbations, density contrast and velocity;
perform the transformation between the synchronous coordinates; and identify
the residual gauge modes in the 2nd-order solutions. In addition, we present
the 2nd-order gauge transformations of the solutions from synchronous to
Poisson coordinates. To apply these formal solutions to concrete cosmological
study, one needs to choose proper initial conditions and do several numerical
integrals.
| [
{
"created": "Wed, 8 May 2019 18:01:24 GMT",
"version": "v1"
},
{
"created": "Tue, 28 May 2019 02:37:12 GMT",
"version": "v2"
},
{
"created": "Wed, 26 Jun 2019 13:26:56 GMT",
"version": "v3"
}
] | 2019-06-27 | [
[
"Wang",
"Bo",
""
],
[
"Zhang",
"Yang",
""
]
] | We continue to study the 2nd-order cosmological perturbations in synchronous coordinates in the framework of the general relativity (GR) during the radiation dominated (RD) stage, and to focus on the scalar-tensor and tensor-tensor couplings. The 1st-order curl velocity and the associated 1st-order vector metric perturbations are assumed to be vanishing. By analytically solving the 2nd-order Einstein equation and the energy-momentum conservation equations, we obtain the 2nd-order formal solutions (in the integral form) of all the metric perturbations, density contrast and velocity; perform the transformation between the synchronous coordinates; and identify the residual gauge modes in the 2nd-order solutions. In addition, we present the 2nd-order gauge transformations of the solutions from synchronous to Poisson coordinates. To apply these formal solutions to concrete cosmological study, one needs to choose proper initial conditions and do several numerical integrals. |
1701.00699 | David Edward Bruschi Dr | David Edward Bruschi | On the gravitational nature of energy | 4 Pages. No figures | null | null | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose the idea that not all energy is a source of gravity. We discuss
the role of energy in the theory of gravitation and provide a formulation of
gravity which takes into account the quantum nature of the source. We show that
gravity depends dramatically on the entanglement present between the
constituents of the Universe. Applications of the theory and open questions are
also discussed.
| [
{
"created": "Fri, 23 Dec 2016 12:37:26 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Feb 2017 17:20:57 GMT",
"version": "v2"
}
] | 2017-02-20 | [
[
"Bruschi",
"David Edward",
""
]
] | We propose the idea that not all energy is a source of gravity. We discuss the role of energy in the theory of gravitation and provide a formulation of gravity which takes into account the quantum nature of the source. We show that gravity depends dramatically on the entanglement present between the constituents of the Universe. Applications of the theory and open questions are also discussed. |
1906.05393 | Adria Delhom | Adria Delhom, Iarley P. Lobo, Gonzalo J. Olmo and Carlos Romero | A generalized Weyl structure with arbitrary non-metricity | 9 pages, updated to match published version, some discussions
extended | Eur. Phys. J. C 79:878 (2019) | 10.1140/epjc/s10052-019-7394-z | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A Weyl structure is usually defined by an equivalence class of pairs $({\bf
g}, \boldsymbol{\omega})$ related by Weyl transformations, which preserve the
relation $\nabla {\bf g}=\boldsymbol{\omega}\otimes{\bf g}$, where ${\bf g}$
and $\boldsymbol{\omega}$ denote the metric tensor and a 1-form field. An
equivalent way of defining such a structure is as an equivalence class of
conformally related metrics with a unique affine connection
$\Gamma_{\boldsymbol{\omega}}$, which is invariant under Weyl transformations.
In a standard Weyl structure, this unique connection is assumed to be
torsion-free and have vectorial non-metricity. This second view allows us to
present two different generalizations of standard Weyl structures. The first
one relies on conformal symmetry while allowing for a general non-metricity
tensor, and the other comes from extending the symmetry to arbitrary
(disformal) transformations of the metric.
| [
{
"created": "Wed, 12 Jun 2019 21:41:11 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Oct 2019 19:38:59 GMT",
"version": "v2"
}
] | 2019-11-01 | [
[
"Delhom",
"Adria",
""
],
[
"Lobo",
"Iarley P.",
""
],
[
"Olmo",
"Gonzalo J.",
""
],
[
"Romero",
"Carlos",
""
]
] | A Weyl structure is usually defined by an equivalence class of pairs $({\bf g}, \boldsymbol{\omega})$ related by Weyl transformations, which preserve the relation $\nabla {\bf g}=\boldsymbol{\omega}\otimes{\bf g}$, where ${\bf g}$ and $\boldsymbol{\omega}$ denote the metric tensor and a 1-form field. An equivalent way of defining such a structure is as an equivalence class of conformally related metrics with a unique affine connection $\Gamma_{\boldsymbol{\omega}}$, which is invariant under Weyl transformations. In a standard Weyl structure, this unique connection is assumed to be torsion-free and have vectorial non-metricity. This second view allows us to present two different generalizations of standard Weyl structures. The first one relies on conformal symmetry while allowing for a general non-metricity tensor, and the other comes from extending the symmetry to arbitrary (disformal) transformations of the metric. |
1702.08118 | De-Cheng Zou | De-Cheng Zou, Yunqi Liu and Ruihong Yue | Behavior of quasinormal modes and Van der Waals-like phase transition of
charged AdS black holes in massive gravity | 18 pages, V3: minor corrections | Eur. Phys. J. C (2017) 77:365 | 10.1140/epjc/s10052-017-4937-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we utilize the quasinormal modes (QNMs) of a massless scalar
perturbation to probe the Van der Waals-like small and large black holes
(SBH/LBH) phase transition of charged topological Anti-de Sitter (AdS) black
holes in four-dimensional massive gravity. We find that the signature of this
SBH/LBH phase transition is detected in the isobaric as well as in the
isothermal process.This further supports the idea that the QNMs can be an
efficient tool to investigate the thermodynamical phase transition.
| [
{
"created": "Mon, 27 Feb 2017 01:05:33 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Feb 2017 07:51:13 GMT",
"version": "v2"
},
{
"created": "Sat, 3 Jun 2017 05:35:23 GMT",
"version": "v3"
}
] | 2017-06-06 | [
[
"Zou",
"De-Cheng",
""
],
[
"Liu",
"Yunqi",
""
],
[
"Yue",
"Ruihong",
""
]
] | In this work, we utilize the quasinormal modes (QNMs) of a massless scalar perturbation to probe the Van der Waals-like small and large black holes (SBH/LBH) phase transition of charged topological Anti-de Sitter (AdS) black holes in four-dimensional massive gravity. We find that the signature of this SBH/LBH phase transition is detected in the isobaric as well as in the isothermal process.This further supports the idea that the QNMs can be an efficient tool to investigate the thermodynamical phase transition. |
1803.01157 | Timothy Clifton | Timothy Clifton, Viraj A. A. Sanghai | Parametrizing theories of gravity on large and small scales in cosmology | 5 pages, 1 figure | Phys. Rev. Lett. 122, 011301 (2019) | 10.1103/PhysRevLett.122.011301 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a link between parametrizations of alternative theories of gravity
on large and small scales in cosmology. This relationship is established using
theoretical consistency conditions only. We find that in both limits the "slip"
and "effective Newton's constant" can be written in terms of a set of four
functions of time, two of which are direct generalizations of the $\alpha$ and
$\gamma$ parameters from post-Newtonian physics. This generalizes previous work
that has constructed frameworks for testing gravity on small scales, and is to
the best of our knowledge the first time that a link between parametrizations
of gravity on such very different scales has been established. We expect our
result to facilitate the imposition of observational constraints, by
drastically reducing the number of functional degrees of freedom required to
consistently test gravity on multiple scales in cosmology.
| [
{
"created": "Sat, 3 Mar 2018 13:05:28 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Jan 2019 10:51:49 GMT",
"version": "v2"
}
] | 2019-01-09 | [
[
"Clifton",
"Timothy",
""
],
[
"Sanghai",
"Viraj A. A.",
""
]
] | We present a link between parametrizations of alternative theories of gravity on large and small scales in cosmology. This relationship is established using theoretical consistency conditions only. We find that in both limits the "slip" and "effective Newton's constant" can be written in terms of a set of four functions of time, two of which are direct generalizations of the $\alpha$ and $\gamma$ parameters from post-Newtonian physics. This generalizes previous work that has constructed frameworks for testing gravity on small scales, and is to the best of our knowledge the first time that a link between parametrizations of gravity on such very different scales has been established. We expect our result to facilitate the imposition of observational constraints, by drastically reducing the number of functional degrees of freedom required to consistently test gravity on multiple scales in cosmology. |
gr-qc/0608027 | Douglas Fregolente | Douglas Fregolente, George E. A. Matsas (Sao Paulo, IFT), Daniel A. T.
Vanzella (Sao Paulo U., Sao Carlos) | Semiclassical approach to the decay of protons in circular motion under
the influence of gravitational fields | To appear in Physical Review D | Phys.Rev. D74 (2006) 045032 | 10.1103/PhysRevD.74.045032 | null | gr-qc hep-th | null | We investigate the possible decay of protons in geodesic circular motion
around neutral compact objects. Weak and strong decay rates and the associated
emitted powers are calculated using a semi-classical approach. Our results are
discussed with respect to distinct ones in the literature, which consider the
decay of accelerated protons in electromagnetic fields. A number of consistency
checks are presented along the paper.
| [
{
"created": "Fri, 4 Aug 2006 14:14:45 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Fregolente",
"Douglas",
"",
"Sao Paulo, IFT"
],
[
"Matsas",
"George E. A.",
"",
"Sao Paulo, IFT"
],
[
"Vanzella",
"Daniel A. T.",
"",
"Sao Paulo U., Sao Carlos"
]
] | We investigate the possible decay of protons in geodesic circular motion around neutral compact objects. Weak and strong decay rates and the associated emitted powers are calculated using a semi-classical approach. Our results are discussed with respect to distinct ones in the literature, which consider the decay of accelerated protons in electromagnetic fields. A number of consistency checks are presented along the paper. |
1008.0382 | Ernesto F. Eiroa | Ernesto F. Eiroa, Claudio Simeone | Brans-Dicke cylindrical wormholes | 11 pages, 3 figures; v3: corrected version, conclusions unchanged | Phys.Rev.D82:084039,2010 | 10.1103/PhysRevD.82.084039 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Static axisymmetric thin-shell wormholes are constructed within the framework
of the Brans-Dicke scalar-tensor theory of gravity. Examples of wormholes
associated with vacuum and electromagnetic fields are studied. All
constructions must be threaded by exotic matter, except in the case of
geometries with a singularity of finite radius, associated with an electric
field, which can have a throat supported by ordinary matter. These results are
achieved with any of the two definitions of the flare-out condition considered.
| [
{
"created": "Mon, 2 Aug 2010 19:24:01 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Oct 2010 20:17:58 GMT",
"version": "v2"
},
{
"created": "Thu, 11 Feb 2016 19:37:25 GMT",
"version": "v3"
}
] | 2016-02-12 | [
[
"Eiroa",
"Ernesto F.",
""
],
[
"Simeone",
"Claudio",
""
]
] | Static axisymmetric thin-shell wormholes are constructed within the framework of the Brans-Dicke scalar-tensor theory of gravity. Examples of wormholes associated with vacuum and electromagnetic fields are studied. All constructions must be threaded by exotic matter, except in the case of geometries with a singularity of finite radius, associated with an electric field, which can have a throat supported by ordinary matter. These results are achieved with any of the two definitions of the flare-out condition considered. |
1806.03807 | Yen-Kheng Lim | Yen-Kheng Lim and Qing-hai Wang | Field equations and particle motion in covariant emergent gravity | New section added. Accepted for publication in Phys. Rev. D | Phys. Rev. D 98, 124029 (2018) | 10.1103/PhysRevD.98.124029 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the full set of field equations based on Hossenfelder's recent
covariant formulation of the emergent gravity model, along with perturbative
and exact solutions. The exact solution describes a static,
spherically-symmetric spacetime with a non-trivial vector field which plays the
role of dark matter under the emergent gravity paradigm. Equations of motion of
relativistic test masses are derived and are shown to reduce to Modified
Newtonian Dynamics with additional relativistic corrections. It is also shown
that the presence of the vector field gives an additional positive contribution
to the bending angle in the deflection of light.
| [
{
"created": "Mon, 11 Jun 2018 04:55:55 GMT",
"version": "v1"
},
{
"created": "Sat, 1 Dec 2018 12:24:27 GMT",
"version": "v2"
}
] | 2018-12-26 | [
[
"Lim",
"Yen-Kheng",
""
],
[
"Wang",
"Qing-hai",
""
]
] | We derive the full set of field equations based on Hossenfelder's recent covariant formulation of the emergent gravity model, along with perturbative and exact solutions. The exact solution describes a static, spherically-symmetric spacetime with a non-trivial vector field which plays the role of dark matter under the emergent gravity paradigm. Equations of motion of relativistic test masses are derived and are shown to reduce to Modified Newtonian Dynamics with additional relativistic corrections. It is also shown that the presence of the vector field gives an additional positive contribution to the bending angle in the deflection of light. |
gr-qc/9801013 | Uwe Gunther | U. Guenther, S. Kriskiv, A. Zhuk | On stable compactification with Casimir-like potential | 17 pages, Latex2e, submitted to Gravitation and Cosmology, slightly
revised Appendix B | Grav.Cosmol. 4 (1998) 1-16 | null | null | gr-qc astro-ph hep-th | null | Multidimensional cosmological models with a higher dimensional space-time
manifold are investigated under dimensional reduction. In the Einstein
conformal frame, the effective potential for the internal scale factors is
obtained. The stable compactification of the internal spaces is achieved due to
the Casimir effect. In the case of more than one internal space a Casimir-like
ansatz for the energy density of the massless scalar field fluctuations is
proposed. Stable configurations with respect to the internal scale factor
excitations are found in the cases of one and two internal spaces.
| [
{
"created": "Thu, 8 Jan 1998 00:59:08 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Jan 1998 01:57:03 GMT",
"version": "v2"
},
{
"created": "Tue, 13 Jan 1998 11:12:52 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Guenther",
"U.",
""
],
[
"Kriskiv",
"S.",
""
],
[
"Zhuk",
"A.",
""
]
] | Multidimensional cosmological models with a higher dimensional space-time manifold are investigated under dimensional reduction. In the Einstein conformal frame, the effective potential for the internal scale factors is obtained. The stable compactification of the internal spaces is achieved due to the Casimir effect. In the case of more than one internal space a Casimir-like ansatz for the energy density of the massless scalar field fluctuations is proposed. Stable configurations with respect to the internal scale factor excitations are found in the cases of one and two internal spaces. |
2011.13135 | Snehasish Bhattacharjee | Snehasish Bhattacharjee | Growth Rate and Configurational Entropy in Tsallis Holographic Dark
Energy | null | European Physical Journal C 81, 217 (2021) | 10.1140/epjc/s10052-021-09003-0 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | In this work, we analyzed the effect of different prescriptions of the IR
cutoffs, namely the Hubble horizon cutoff, particle horizon cutoff, Granda and
Oliveros horizon cut off, and the Ricci horizon cutoff on the growth rate of
clustering for the Tsallis holographic dark energy (THDE) model in an FRW
universe devoid of any interactions between the dark Universe. Furthermore, we
used the concept of configurational entropy to derive constraints
(qualitatively) on the model parameters for the THDE model in each IR cutoff
prescription from the fact that the rate of change of configurational entropy
hits a minimum at a particular scale factor $a_{DE}$ which indicate precisely
the epoch of dark energy domination predicted by the relevant cosmological
model as a function of the model parameter(s). By using the current
observational constraints on the redshift of transition from a decelerated to
an accelerated Universe, we derived constraints on the model parameters
appearing in each IR cutoff definition and on the non-additivity parameter
$\delta$ characterizing the THDE model and report the existence of simple
linear dependency between $\delta$ and $a_{DE}$ in each IR cutoff setup.
| [
{
"created": "Thu, 26 Nov 2020 05:41:11 GMT",
"version": "v1"
},
{
"created": "Mon, 8 Mar 2021 06:12:37 GMT",
"version": "v2"
}
] | 2021-03-09 | [
[
"Bhattacharjee",
"Snehasish",
""
]
] | In this work, we analyzed the effect of different prescriptions of the IR cutoffs, namely the Hubble horizon cutoff, particle horizon cutoff, Granda and Oliveros horizon cut off, and the Ricci horizon cutoff on the growth rate of clustering for the Tsallis holographic dark energy (THDE) model in an FRW universe devoid of any interactions between the dark Universe. Furthermore, we used the concept of configurational entropy to derive constraints (qualitatively) on the model parameters for the THDE model in each IR cutoff prescription from the fact that the rate of change of configurational entropy hits a minimum at a particular scale factor $a_{DE}$ which indicate precisely the epoch of dark energy domination predicted by the relevant cosmological model as a function of the model parameter(s). By using the current observational constraints on the redshift of transition from a decelerated to an accelerated Universe, we derived constraints on the model parameters appearing in each IR cutoff definition and on the non-additivity parameter $\delta$ characterizing the THDE model and report the existence of simple linear dependency between $\delta$ and $a_{DE}$ in each IR cutoff setup. |
1102.1867 | Laszlo B. Szabados | J\"org Frauendiener, L\'aszl\'o B Szabados | A note on the post-Newtonian limit of quasi-local energy expressions | final version, 12 pages, The last sentence of subsection 2.2, giving
the quasi-local energy in the relativistically corrected Newtonian theory, is
corrected | Class. Quantum Grav. vol 28 (2011) 235009, Corrigendum: Class.
Quantum Grav. vol 29 (2012) 069501 | 10.1088/0264-9381/28/23/235009 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An `effective' quasi-local energy expression, motivated by the
(relativistically corrected) Newtonian theory, is introduced in exact GR as the
volume integral of all the source terms in the field equation for the Newtonian
potential in static spacetimes. In particular, we exhibit a new post-Newtonian
correction in the source term in the field equation for the Newtonian
gravitational potential. In asymptotically flat spacetimes this expression
tends to the ADM energy at the spatial infinity as a {\em monotonically
decreasing} set function. We prove its positivity in spherically symmetric
spacetimes under certain energy conditions, and that its vanishing
characterizes flatness. We argue that any physically acceptable quasi-local
energy expression should behave qualitatively like this `effective' energy
expression in this limit.
| [
{
"created": "Wed, 9 Feb 2011 14:12:46 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Nov 2011 23:49:34 GMT",
"version": "v2"
},
{
"created": "Tue, 28 Feb 2012 16:33:51 GMT",
"version": "v3"
}
] | 2015-05-27 | [
[
"Frauendiener",
"Jörg",
""
],
[
"Szabados",
"László B",
""
]
] | An `effective' quasi-local energy expression, motivated by the (relativistically corrected) Newtonian theory, is introduced in exact GR as the volume integral of all the source terms in the field equation for the Newtonian potential in static spacetimes. In particular, we exhibit a new post-Newtonian correction in the source term in the field equation for the Newtonian gravitational potential. In asymptotically flat spacetimes this expression tends to the ADM energy at the spatial infinity as a {\em monotonically decreasing} set function. We prove its positivity in spherically symmetric spacetimes under certain energy conditions, and that its vanishing characterizes flatness. We argue that any physically acceptable quasi-local energy expression should behave qualitatively like this `effective' energy expression in this limit. |
1912.09000 | Miguel Sabido | Luis R. Diaz-Barron and M. Sabido | On Emergent Gravity, Ungravity and $\Lambda$ | 4 pages, 1 figure | null | 10.1016/j.physletb.2021.136365 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we study the "ungravity" modifications to the Friedmann
equations. By using the first law of thermodynamics and the modified entropy
area relationship derived from the "ungravity" contributions to the
Schwarzschild black hole, we obtain modifications to the Friedmann equation
that in the late time regime gives an effective cosmological constant.
Therefore, this simple model can provide an "ungravity" origin to the
cosmological constant $\Lambda$.
| [
{
"created": "Thu, 19 Dec 2019 03:12:18 GMT",
"version": "v1"
}
] | 2021-05-19 | [
[
"Diaz-Barron",
"Luis R.",
""
],
[
"Sabido",
"M.",
""
]
] | In this paper we study the "ungravity" modifications to the Friedmann equations. By using the first law of thermodynamics and the modified entropy area relationship derived from the "ungravity" contributions to the Schwarzschild black hole, we obtain modifications to the Friedmann equation that in the late time regime gives an effective cosmological constant. Therefore, this simple model can provide an "ungravity" origin to the cosmological constant $\Lambda$. |
2012.07874 | Simeon Bird | Barry C. Barish, Simeon Bird, Yanou Cui | Impact of a Midband Gravitational Wave Experiment On Detectability of
Cosmological Stochastic Gravitational Wave Backgrounds | Matches version accepted to PRD. 14 pages, 8 figures, code available
at https://github.com/sbird/grav_midband | Phys. Rev. D 103, 123541 (2021) | 10.1103/PhysRevD.103.123541 | null | gr-qc astro-ph.CO hep-ex hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We make forecasts for the impact a future "midband" space-based gravitational
wave experiment, most sensitive to $10^{-2}- 10$ Hz, could have on potential
detections of cosmological stochastic gravitational wave backgrounds (SGWBs).
Specific proposed midband experiments considered are TianGo, B-DECIGO and
AEDGE. We propose a combined power-law integrated sensitivity (CPLS) curve
combining GW experiments over different frequency bands, which shows the
midband improves sensitivity to SGWBs by up to two orders of magnitude at
$10^{-2} - 10$ Hz. We consider GW emission from cosmic strings and phase
transitions as benchmark examples of cosmological SGWBs. We explicitly model
various astrophysical SGWB sources, most importantly from unresolved black hole
mergers. Using Markov Chain Monte Carlo, we demonstrated that midband
experiments can, when combined with LIGO A+ and LISA, significantly improve
sensitivities to cosmological SGWBs and better separate them from astrophysical
SGWBs. In particular, we forecast that a midband experiment improves
sensitivity to cosmic string tension $G\mu$ by up to a factor of $10$, driven
by improved component separation from astrophysical sources. For phase
transitions, a midband experiment can detect signals peaking at $0.1 - 1$ Hz,
which for our fiducial model corresponds to early Universe temperatures of
$T_*\sim 10^4 - 10^6$ GeV, generally beyond the reach of LIGO and LISA. The
midband closes an energy gap and better captures characteristic spectral shape
information. It thus substantially improves measurement of the properties of
phase transitions at lower energies of $T_* \sim O(10^3)$ GeV, potentially
relevant to new physics at the electroweak scale, whereas in this energy range
LISA alone will detect an excess but not effectively measure the phase
transition parameters. Our modelling code and chains are publicly available.
| [
{
"created": "Mon, 14 Dec 2020 19:00:25 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Jun 2021 18:43:47 GMT",
"version": "v2"
}
] | 2021-06-30 | [
[
"Barish",
"Barry C.",
""
],
[
"Bird",
"Simeon",
""
],
[
"Cui",
"Yanou",
""
]
] | We make forecasts for the impact a future "midband" space-based gravitational wave experiment, most sensitive to $10^{-2}- 10$ Hz, could have on potential detections of cosmological stochastic gravitational wave backgrounds (SGWBs). Specific proposed midband experiments considered are TianGo, B-DECIGO and AEDGE. We propose a combined power-law integrated sensitivity (CPLS) curve combining GW experiments over different frequency bands, which shows the midband improves sensitivity to SGWBs by up to two orders of magnitude at $10^{-2} - 10$ Hz. We consider GW emission from cosmic strings and phase transitions as benchmark examples of cosmological SGWBs. We explicitly model various astrophysical SGWB sources, most importantly from unresolved black hole mergers. Using Markov Chain Monte Carlo, we demonstrated that midband experiments can, when combined with LIGO A+ and LISA, significantly improve sensitivities to cosmological SGWBs and better separate them from astrophysical SGWBs. In particular, we forecast that a midband experiment improves sensitivity to cosmic string tension $G\mu$ by up to a factor of $10$, driven by improved component separation from astrophysical sources. For phase transitions, a midband experiment can detect signals peaking at $0.1 - 1$ Hz, which for our fiducial model corresponds to early Universe temperatures of $T_*\sim 10^4 - 10^6$ GeV, generally beyond the reach of LIGO and LISA. The midband closes an energy gap and better captures characteristic spectral shape information. It thus substantially improves measurement of the properties of phase transitions at lower energies of $T_* \sim O(10^3)$ GeV, potentially relevant to new physics at the electroweak scale, whereas in this energy range LISA alone will detect an excess but not effectively measure the phase transition parameters. Our modelling code and chains are publicly available. |
1001.2828 | Hongsu Kim | Dong-Hoon Kim | Spinning binary waveforms via PN expansion: Equal-mass case | 9 pages, 1 figure | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Complete expressions of time-domain gravitational waveforms for spinning
binary inspirals via the post-Newtonian (PN) approximation would require
determination of the phase, amplitude, inclination angle, precession phase and
spin vectors as well as the knowledge of the order coefficients for the PN
expansion terms. These quantities are determined by solving simultaneously the
spin-precession equations, the evolution equation for the Newtonian angular
momentum, and the equation for the orbital frequency. For the spinning binaries
with equal masses, determination of these quantities can be done fully
analytically, by taking advantage of the equal mass symmetry, therefore by
simplifying those equations to solve. We provide the analytical results through
1.5 PN order which includes spin-orbit interactions.
| [
{
"created": "Sat, 16 Jan 2010 14:14:39 GMT",
"version": "v1"
}
] | 2010-01-19 | [
[
"Kim",
"Dong-Hoon",
""
]
] | Complete expressions of time-domain gravitational waveforms for spinning binary inspirals via the post-Newtonian (PN) approximation would require determination of the phase, amplitude, inclination angle, precession phase and spin vectors as well as the knowledge of the order coefficients for the PN expansion terms. These quantities are determined by solving simultaneously the spin-precession equations, the evolution equation for the Newtonian angular momentum, and the equation for the orbital frequency. For the spinning binaries with equal masses, determination of these quantities can be done fully analytically, by taking advantage of the equal mass symmetry, therefore by simplifying those equations to solve. We provide the analytical results through 1.5 PN order which includes spin-orbit interactions. |
gr-qc/0410062 | Gioel Calabrese | Gioel Calabrese | Finite differencing second order systems describing black hole
spacetimes | null | Phys.Rev. D71 (2005) 027501 | 10.1103/PhysRevD.71.027501 | null | gr-qc | null | Keeping Einstein's equations in second order form can be appealing for
computational efficiency, because of the reduced number of variables and
constraints. Stability issues emerge, however, which are not present in first
order formulations. We show that a standard discretization of the second order
``shifted'' wave equation leads to an unstable semi-discrete scheme if the
shift parameter is too large. This implies that discretizations obtained using
integrators such as Runge-Kutta, Crank-Nicholson, leap-frog are unstable for
any fixed value of the Courant factor. We argue that this situation arises in
numerical relativity, particularly in simulations of spacetimes containing
black holes, and discuss several ways of circumventing this problem. We find
that the first order reduction in time based on ``ADM'' type variables is very
effective.
| [
{
"created": "Thu, 14 Oct 2004 21:09:48 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Calabrese",
"Gioel",
""
]
] | Keeping Einstein's equations in second order form can be appealing for computational efficiency, because of the reduced number of variables and constraints. Stability issues emerge, however, which are not present in first order formulations. We show that a standard discretization of the second order ``shifted'' wave equation leads to an unstable semi-discrete scheme if the shift parameter is too large. This implies that discretizations obtained using integrators such as Runge-Kutta, Crank-Nicholson, leap-frog are unstable for any fixed value of the Courant factor. We argue that this situation arises in numerical relativity, particularly in simulations of spacetimes containing black holes, and discuss several ways of circumventing this problem. We find that the first order reduction in time based on ``ADM'' type variables is very effective. |
2204.08881 | Chao Zhang | Chao Zhang and Yungui Gong | Detecting electric charge with Extreme Mass Ratio Inspirals | 14 pages, 3 figures, 1 table; v2: references added | null | 10.1103/PhysRevD.105.124046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider extreme mass ratio inspirals during which an electrically charged
compact object with mass $m_p$ and the charge to mass ratio $q$ inspirals
around a Schwarzschild black hole of mass $M$. Using the Teukolsky and
generalized Sasaki-Nakamura formalisms for the gravitational and
electromagnetic perturbations around a Schwarzschild black hole, we numerically
calculate the energy flux of both gravitational and electromagnetic waves
induced by a charged particle moving in circular orbits. With one year
observation of these extreme mass ratio inspirals, we show that space-based
gravitational wave detector such as the Laser Interferometer Space Antenna can
detect the charge to mass ratio as small as $q\sim 10^{-3}$.
| [
{
"created": "Tue, 19 Apr 2022 13:27:17 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Apr 2022 03:20:02 GMT",
"version": "v2"
}
] | 2022-07-13 | [
[
"Zhang",
"Chao",
""
],
[
"Gong",
"Yungui",
""
]
] | We consider extreme mass ratio inspirals during which an electrically charged compact object with mass $m_p$ and the charge to mass ratio $q$ inspirals around a Schwarzschild black hole of mass $M$. Using the Teukolsky and generalized Sasaki-Nakamura formalisms for the gravitational and electromagnetic perturbations around a Schwarzschild black hole, we numerically calculate the energy flux of both gravitational and electromagnetic waves induced by a charged particle moving in circular orbits. With one year observation of these extreme mass ratio inspirals, we show that space-based gravitational wave detector such as the Laser Interferometer Space Antenna can detect the charge to mass ratio as small as $q\sim 10^{-3}$. |
1408.6205 | Alexey Koshelev | Aindriu Conroy, Alexey S. Koshelev, Anupam Mazumdar | Geodesic completeness and homogeneity condition for cosmic inflation | 4 pages, 1 figure | Phys. Rev. D 90, 123525 (2014) | 10.1103/PhysRevD.90.123525 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | There are two disjointed problems in cosmology within General Relativity
(GR), which can be addressed simultaneously by studying the nature of geodesics
around $t\rightarrow 0$, where $t$ is the physical time. One is related to the
past geodesic completeness of the inflationary trajectory due to the presence
of a cosmological singularity, and the other one is related to the homogeneity
condition required to inflate a local space-time patch of the universe. We will
show that both the problems have a common origin, arising from how the causal
structure of null and timelike geodesics are structured within GR. In
particular, we will show how a non-local extension of GR can address both
problems, while satisfying the null energy condition for the matter sources.
| [
{
"created": "Tue, 26 Aug 2014 18:36:47 GMT",
"version": "v1"
}
] | 2014-12-24 | [
[
"Conroy",
"Aindriu",
""
],
[
"Koshelev",
"Alexey S.",
""
],
[
"Mazumdar",
"Anupam",
""
]
] | There are two disjointed problems in cosmology within General Relativity (GR), which can be addressed simultaneously by studying the nature of geodesics around $t\rightarrow 0$, where $t$ is the physical time. One is related to the past geodesic completeness of the inflationary trajectory due to the presence of a cosmological singularity, and the other one is related to the homogeneity condition required to inflate a local space-time patch of the universe. We will show that both the problems have a common origin, arising from how the causal structure of null and timelike geodesics are structured within GR. In particular, we will show how a non-local extension of GR can address both problems, while satisfying the null energy condition for the matter sources. |
0902.0803 | Travis Garrett | Travis Garrett | A Simple, Direct Finite Differencing of the Einstein Equations | 5 pages, 1 figure | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate a simple variation of the Generalized Harmonic method for
evolving the Einstein equations. A flat space wave equation for metric
perturbations is separated from the Ricci tensor, with the rest of the Ricci
tensor becoming a source for these wave equations. We demonstrate that this
splitting method allows for the accurate simulation of compact objects, with
gravitational field strengths less than or equal to those of neutron stars.
This method could thus provide a straightforward path for general relativistic
effects to be added to astrophysics simulations, such as in core collapse,
accretion disks, and extreme mass ratio systems.
| [
{
"created": "Wed, 4 Feb 2009 21:48:31 GMT",
"version": "v1"
}
] | 2009-02-06 | [
[
"Garrett",
"Travis",
""
]
] | We investigate a simple variation of the Generalized Harmonic method for evolving the Einstein equations. A flat space wave equation for metric perturbations is separated from the Ricci tensor, with the rest of the Ricci tensor becoming a source for these wave equations. We demonstrate that this splitting method allows for the accurate simulation of compact objects, with gravitational field strengths less than or equal to those of neutron stars. This method could thus provide a straightforward path for general relativistic effects to be added to astrophysics simulations, such as in core collapse, accretion disks, and extreme mass ratio systems. |
1401.4640 | Cosimo Bambi | Cosimo Bambi | Testing the Bardeen metric with the black hole candidate in Cygnus X-1 | 5 pages, 2 figures. v2: a few typos corrected | Phys.Lett.B730:59-62,2014 | 10.1016/j.physletb.2014.01.037 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In general, it is very difficult to test the Kerr-nature of an astrophysical
black hole candidate, because it is not possible to have independent
measurements of both the spin parameter $a_*$ and possible deviations from the
Kerr solution. Non-Kerr objects may indeed look like Kerr black holes with
different spin. However, it is much more difficult to mimic an extremal Kerr
black hole. The black hole candidate in Cygnus X-1 has the features of a near
extremal Kerr black hole, and it is therefore a good object to test the Kerr
black hole paradigm. The 3$\sigma$-bounds $a_* > 0.95$ and $a_* > 0.983$
reported in the literature and valid in the Kerr spacetime become,
respectively, $a_* > 0.78$ and $|g/M| < 0.41$, and $a_* > 0.89$ and $|g/M| <
0.28$ in the Bardeen metric, where $g$ is the Bardeen charge of the black hole.
| [
{
"created": "Sun, 19 Jan 2014 06:57:26 GMT",
"version": "v1"
},
{
"created": "Sat, 25 Jan 2014 19:53:51 GMT",
"version": "v2"
}
] | 2014-01-28 | [
[
"Bambi",
"Cosimo",
""
]
] | In general, it is very difficult to test the Kerr-nature of an astrophysical black hole candidate, because it is not possible to have independent measurements of both the spin parameter $a_*$ and possible deviations from the Kerr solution. Non-Kerr objects may indeed look like Kerr black holes with different spin. However, it is much more difficult to mimic an extremal Kerr black hole. The black hole candidate in Cygnus X-1 has the features of a near extremal Kerr black hole, and it is therefore a good object to test the Kerr black hole paradigm. The 3$\sigma$-bounds $a_* > 0.95$ and $a_* > 0.983$ reported in the literature and valid in the Kerr spacetime become, respectively, $a_* > 0.78$ and $|g/M| < 0.41$, and $a_* > 0.89$ and $|g/M| < 0.28$ in the Bardeen metric, where $g$ is the Bardeen charge of the black hole. |
2005.05798 | Fay\c{c}al Hammad | Fay\c{c}al Hammad and Alexandre Landry | A simple superconductor quantum interference device for testing gravity | 20 pages, 1 figure, references updated, title slightly improved | Mod. Phys. Lett. 35, 2050171 (2020) | 10.1142/S0217732320501710 | null | gr-qc cond-mat.supr-con | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A simple tabletop setup based on a superconducting quantum interference
device is proposed for testing the gravitational interaction. A D-shaped
superconducting loop has the straight segment immersed inside a massive sphere
while the half-circle segment is wrapped around the sphere. The superconducting
condensate within the straight arm of the loop thus bathes inside a
gravitational simple harmonic oscillator potential while the condensate in the
half-circle arm bathes in the constant gravitational potential around the
sphere. The resulting phase difference at the Josephson junctions on both sides
of the straight arm induces a sinusoidal electric current that has a frequency
determined by the precise gravitational potential due to the massive sphere.
| [
{
"created": "Sat, 9 May 2020 17:50:06 GMT",
"version": "v1"
},
{
"created": "Tue, 30 Jun 2020 21:23:24 GMT",
"version": "v2"
}
] | 2020-07-02 | [
[
"Hammad",
"Fayçal",
""
],
[
"Landry",
"Alexandre",
""
]
] | A simple tabletop setup based on a superconducting quantum interference device is proposed for testing the gravitational interaction. A D-shaped superconducting loop has the straight segment immersed inside a massive sphere while the half-circle segment is wrapped around the sphere. The superconducting condensate within the straight arm of the loop thus bathes inside a gravitational simple harmonic oscillator potential while the condensate in the half-circle arm bathes in the constant gravitational potential around the sphere. The resulting phase difference at the Josephson junctions on both sides of the straight arm induces a sinusoidal electric current that has a frequency determined by the precise gravitational potential due to the massive sphere. |
gr-qc/0412002 | Harald P. Pfeiffer | Harald P. Pfeiffer | The initial value problem in numerical relativity | Contribution to the proceedings of "Miami Waves Conference 2004", 24
pages | null | null | null | gr-qc | null | The conformal method for constructing initial data for Einstein's equations
is presented in both the Hamiltonian and Lagrangian picture (extrinsic
curvature decomposition and conformal thin sandwich formalism, respectively),
and advantages due to the recent introduction of a weight-function in the
extrinsic curvature decomposition are discussed. I then describe recent
progress in numerical techniques to solve the resulting elliptic equations, and
explore innovative approaches toward the construction of astrophysically
realistic initial data for binary black hole simulations.
| [
{
"created": "Wed, 1 Dec 2004 17:32:50 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Pfeiffer",
"Harald P.",
""
]
] | The conformal method for constructing initial data for Einstein's equations is presented in both the Hamiltonian and Lagrangian picture (extrinsic curvature decomposition and conformal thin sandwich formalism, respectively), and advantages due to the recent introduction of a weight-function in the extrinsic curvature decomposition are discussed. I then describe recent progress in numerical techniques to solve the resulting elliptic equations, and explore innovative approaches toward the construction of astrophysically realistic initial data for binary black hole simulations. |
gr-qc/9806078 | Jong Hyuk Yoon | Jong Hyuk Yoon | Quasi-Local Energy Conservation Law Derived From The Einstein's
Equations | 10 pages, 1 figure, RevTex | null | null | null | gr-qc | null | The quasi-local energy conservation law is derived from the vacuum Einstein's
equations on the timelike boundary surface in the canonical (2,2)-formalism of
general relativity. The quasi-local energy and energy flux integral agree with
the standard results in the asymptotically flat limit and in spherically
symmetric spacetimes.
| [
{
"created": "Fri, 19 Jun 1998 08:42:14 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Yoon",
"Jong Hyuk",
""
]
] | The quasi-local energy conservation law is derived from the vacuum Einstein's equations on the timelike boundary surface in the canonical (2,2)-formalism of general relativity. The quasi-local energy and energy flux integral agree with the standard results in the asymptotically flat limit and in spherically symmetric spacetimes. |
1908.10806 | Pierre-Henri Chavanis | Pierre-Henri Chavanis | Statistical mechanics of self-gravitating systems in general relativity:
I. The quantum Fermi gas | null | Eur. Phys. J. Plus, 135, 290 (2020) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We develop a general formalism to determine the statistical equilibrium
states of self-gravitating systems in general relativity and complete previous
works on the subject. Our results are valid for an arbitrary form of entropy
but, for illustration, we explicitly consider the Fermi-Dirac entropy for
fermions. The maximization of entropy at fixed mass-energy and particle number
determines the distribution function of the system and its equation of state.
It also implies the Tolman-Oppenheimer-Volkoff equations of hydrostatic
equilibrium and the Tolman-Klein relations. Our paper provides all the
necessary equations that are needed to construct the caloric curves of
self-gravitating fermions in general relativity as done in recent works. We
consider the nonrelativistic limit $c\rightarrow +\infty$ and recover the
equations obtained within the framework of Newtonian gravity. We also discuss
the inequivalence of statistical ensembles as well as the relation between the
dynamical and thermodynamical stability of self-gravitating systems in
Newtonian gravity and general relativity.
| [
{
"created": "Wed, 28 Aug 2019 16:16:54 GMT",
"version": "v1"
}
] | 2020-12-24 | [
[
"Chavanis",
"Pierre-Henri",
""
]
] | We develop a general formalism to determine the statistical equilibrium states of self-gravitating systems in general relativity and complete previous works on the subject. Our results are valid for an arbitrary form of entropy but, for illustration, we explicitly consider the Fermi-Dirac entropy for fermions. The maximization of entropy at fixed mass-energy and particle number determines the distribution function of the system and its equation of state. It also implies the Tolman-Oppenheimer-Volkoff equations of hydrostatic equilibrium and the Tolman-Klein relations. Our paper provides all the necessary equations that are needed to construct the caloric curves of self-gravitating fermions in general relativity as done in recent works. We consider the nonrelativistic limit $c\rightarrow +\infty$ and recover the equations obtained within the framework of Newtonian gravity. We also discuss the inequivalence of statistical ensembles as well as the relation between the dynamical and thermodynamical stability of self-gravitating systems in Newtonian gravity and general relativity. |
2310.17291 | C\'edric Jockel | C\'edric Jockel, Laura Sagunski | Fermion Proca Stars: Vector Dark Matter Admixed Neutron Stars | 20 pages, 11 figures, supersedes arXiv:2308.12174. v2: Content
matches published version in Particles (open access)
https://www.mdpi.com/2571-712X/7/1/4 | Particles 2024, 7(1), 52-79 | 10.3390/particles7010004 | null | gr-qc astro-ph.CO astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | Dark matter could accumulate around neutron stars in sufficient amounts to
affect their global properties. In this work, we study the effect of a specific
model for dark matter -- a massive and self-interacting vector (spin-1) field
-- on neutron stars. We describe the combined systems of neutron stars and
vector dark matter using Einstein-Proca theory coupled to a nuclear-matter
term, and find scaling relations between the field and metric components in the
equations of motion. We construct equilibrium solutions of the combined
systems, compute their masses and radii and also analyse their stability and
higher modes. The combined systems admit dark matter (DM) core and cloud
solutions. Core solutions compactify the neutron star component and tend to
decrease the total mass of the combined system. Cloud solutions have the
inverse effect. Electromagnetic observations of certain cloud-like
configurations would appear to violate the Buchdahl limit. This could make
Buchdahl-limit violating objects smoking gun signals for dark matter in neutron
stars. The self-interaction strength is found to significantly affect both mass
and radius. We also compare fermion Proca stars to objects where the dark
matter is modelled using a complex scalar field. We find that fermion Proca
stars tend to be more massive and geometrically larger than their scalar field
counterparts for equal boson masses and self-interaction strengths. Both
systems can produce degenerate masses and radii for different amounts of DM and
DM particle masses.
| [
{
"created": "Thu, 26 Oct 2023 10:15:46 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Jan 2024 10:14:58 GMT",
"version": "v2"
}
] | 2024-01-17 | [
[
"Jockel",
"Cédric",
""
],
[
"Sagunski",
"Laura",
""
]
] | Dark matter could accumulate around neutron stars in sufficient amounts to affect their global properties. In this work, we study the effect of a specific model for dark matter -- a massive and self-interacting vector (spin-1) field -- on neutron stars. We describe the combined systems of neutron stars and vector dark matter using Einstein-Proca theory coupled to a nuclear-matter term, and find scaling relations between the field and metric components in the equations of motion. We construct equilibrium solutions of the combined systems, compute their masses and radii and also analyse their stability and higher modes. The combined systems admit dark matter (DM) core and cloud solutions. Core solutions compactify the neutron star component and tend to decrease the total mass of the combined system. Cloud solutions have the inverse effect. Electromagnetic observations of certain cloud-like configurations would appear to violate the Buchdahl limit. This could make Buchdahl-limit violating objects smoking gun signals for dark matter in neutron stars. The self-interaction strength is found to significantly affect both mass and radius. We also compare fermion Proca stars to objects where the dark matter is modelled using a complex scalar field. We find that fermion Proca stars tend to be more massive and geometrically larger than their scalar field counterparts for equal boson masses and self-interaction strengths. Both systems can produce degenerate masses and radii for different amounts of DM and DM particle masses. |
gr-qc/9506057 | Matej Pavi | Matej Pavsic (Jozef Stefan Institute, University of Ljubljana) | On the Resolution of Time Problem in Quantum Gravity Induced from
Unconstrained Membranes | 22 Pages | Found.Phys.26:159-195,1996 | 10.1007/BF02058084 | null | gr-qc | null | The relativistic theory of unconstrained $p$-dimensional membranes
($p$-branes) is further developed and then applied to the embedding model of
induced gravity. Space-time is considered as a 4-dimensional unconstrained
membrane evolving in an $N$-dimensional embedding space. The parameter of
evolution or the evolution time $\tau$ is a distinct concept from the
coordinate time $t = x^0$. Quantization of the theory is also discussed. A
covariant functional Schr\" odinger equations has a solution for the wave
functional such that it is sharply localized in a certain subspace $P$ of
space-time, and much less sharply localized (though still localized) outside
$P$. With the passage of evolution the region $P$ moves forward in space-time.
Such a solution we interpret as incorporating two seemingly contradictory
observations: (i) experiments clearly indicate that space-time is a continuum
in which events are existing; (ii) not the whole 4-dimensional space-time, but
only a 3-dimensional section which moves forward in time is accessible to our
immediate experience. The notorious problem of time is thus resolved in our
approach to quantum gravity. Finally we include sources into our unconstrained
embedding model. Possible sources are unconstrained worldlines which are free
from the well known problem concerning the Maxwell fields generated by charged
unconstrained point particles.
| [
{
"created": "Tue, 27 Jun 1995 14:36:25 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Jun 1995 12:34:48 GMT",
"version": "v2"
},
{
"created": "Thu, 29 Jun 1995 12:20:50 GMT",
"version": "v3"
}
] | 2014-11-17 | [
[
"Pavsic",
"Matej",
"",
"Jozef Stefan Institute, University of Ljubljana"
]
] | The relativistic theory of unconstrained $p$-dimensional membranes ($p$-branes) is further developed and then applied to the embedding model of induced gravity. Space-time is considered as a 4-dimensional unconstrained membrane evolving in an $N$-dimensional embedding space. The parameter of evolution or the evolution time $\tau$ is a distinct concept from the coordinate time $t = x^0$. Quantization of the theory is also discussed. A covariant functional Schr\" odinger equations has a solution for the wave functional such that it is sharply localized in a certain subspace $P$ of space-time, and much less sharply localized (though still localized) outside $P$. With the passage of evolution the region $P$ moves forward in space-time. Such a solution we interpret as incorporating two seemingly contradictory observations: (i) experiments clearly indicate that space-time is a continuum in which events are existing; (ii) not the whole 4-dimensional space-time, but only a 3-dimensional section which moves forward in time is accessible to our immediate experience. The notorious problem of time is thus resolved in our approach to quantum gravity. Finally we include sources into our unconstrained embedding model. Possible sources are unconstrained worldlines which are free from the well known problem concerning the Maxwell fields generated by charged unconstrained point particles. |
gr-qc/0104026 | T. Damour | Thibault Damour and Alexander Vilenkin | Gravitational wave bursts from cusps and kinks on cosmic strings | 24 pages, 3 figures, Revtex, submitted to Phys. Rev. D | Phys.Rev.D64:064008,2001 | 10.1103/PhysRevD.64.064008 | IHES/P/01/15 | gr-qc astro-ph | null | The strong beams of high-frequency gravitational waves (GW) emitted by cusps
and kinks of cosmic strings are studied in detail. As a consequence of these
beams, the stochastic ensemble of GW's generated by a cosmological network of
oscillating loops is strongly non Gaussian, and includes occasional sharp
bursts that stand above the ``confusion'' GW noise made of many smaller
overlapping bursts. Even if only 10% of all string loops have cusps these
bursts might be detectable by the planned GW detectors LIGO/VIRGO and LISA for
string tensions as small as $G \mu \sim 10^{-13}$. In the implausible case
where the average cusp number per loop oscillation is extremely small, the
smaller bursts emitted by the ubiquitous kinks will be detectable by LISA for
string tensions as small as $G \mu \sim 10^{-12}$. We show that the strongly
non Gaussian nature of the stochastic GW's generated by strings modifies the
usual derivation of constraints on $G \mu$ from pulsar timing experiments. In
particular the usually considered ``rms GW background'' is, when $G \mu \gaq
10^{-7}$, an overestimate of the more relevant confusion GW noise because it
includes rare, intense bursts. The consideration of the confusion GW noise
suggests that a Grand Unified Theory (GUT) value $ G \mu \sim 10^{-6}$ is
compatible with existing pulsar data, and that a modest improvement in pulsar
timing accuracy could detect the confusion noise coming from a network of cuspy
string loops down to $ G \mu \sim 10^{-11}$. The GW bursts discussed here might
be accompanied by Gamma Ray Bursts.
| [
{
"created": "Tue, 10 Apr 2001 07:52:07 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Damour",
"Thibault",
""
],
[
"Vilenkin",
"Alexander",
""
]
] | The strong beams of high-frequency gravitational waves (GW) emitted by cusps and kinks of cosmic strings are studied in detail. As a consequence of these beams, the stochastic ensemble of GW's generated by a cosmological network of oscillating loops is strongly non Gaussian, and includes occasional sharp bursts that stand above the ``confusion'' GW noise made of many smaller overlapping bursts. Even if only 10% of all string loops have cusps these bursts might be detectable by the planned GW detectors LIGO/VIRGO and LISA for string tensions as small as $G \mu \sim 10^{-13}$. In the implausible case where the average cusp number per loop oscillation is extremely small, the smaller bursts emitted by the ubiquitous kinks will be detectable by LISA for string tensions as small as $G \mu \sim 10^{-12}$. We show that the strongly non Gaussian nature of the stochastic GW's generated by strings modifies the usual derivation of constraints on $G \mu$ from pulsar timing experiments. In particular the usually considered ``rms GW background'' is, when $G \mu \gaq 10^{-7}$, an overestimate of the more relevant confusion GW noise because it includes rare, intense bursts. The consideration of the confusion GW noise suggests that a Grand Unified Theory (GUT) value $ G \mu \sim 10^{-6}$ is compatible with existing pulsar data, and that a modest improvement in pulsar timing accuracy could detect the confusion noise coming from a network of cuspy string loops down to $ G \mu \sim 10^{-11}$. The GW bursts discussed here might be accompanied by Gamma Ray Bursts. |
gr-qc/0010076 | Pascual-Sanchez J.-F. | J.-F. Pascual-S\'anchez (University of Valladolid) | A generalized linear Hubble law for an inhomogeneous barotropic Universe | 9 pages, LaTeX, to be published in Class. Quantum Grav | Class.Quant.Grav.17:4913-4918,2000 | 10.1088/0264-9381/17/23/309 | null | gr-qc astro-ph | null | In this work, I present a generalized linear Hubble law for a barotropic
spherically symmetric inhomogeneous spacetime, which is in principle compatible
with the acceleration of the cosmic expansion obtained as a result of high
redshift Supernovae data. The new Hubble function, defined by this law, has two
additional terms besides an expansion one, similar to the usual volume
expansion one of the FLRW models, but now due to an angular expansion. The
first additional term is dipolar and is a consequence of the existence of a
kinematic acceleration of the observer, generated by a negative gradient of
pressure or of mass-energy density. The second one is quadrupolar and due to
the shear. Both additional terms are anisotropic for off-centre observers,
because of to their dependence on a telescopic angle of observation. This
generalized linear Hubble law could explain, in a cosmological setting, the
observed large scale flow of matter, without to have recourse to peculiar
velocity-type newtonian models. It is pointed out also, that the matter dipole
direction should coincide with the CBR dipole one.
| [
{
"created": "Fri, 20 Oct 2000 18:10:05 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Pascual-Sánchez",
"J. -F.",
"",
"University of Valladolid"
]
] | In this work, I present a generalized linear Hubble law for a barotropic spherically symmetric inhomogeneous spacetime, which is in principle compatible with the acceleration of the cosmic expansion obtained as a result of high redshift Supernovae data. The new Hubble function, defined by this law, has two additional terms besides an expansion one, similar to the usual volume expansion one of the FLRW models, but now due to an angular expansion. The first additional term is dipolar and is a consequence of the existence of a kinematic acceleration of the observer, generated by a negative gradient of pressure or of mass-energy density. The second one is quadrupolar and due to the shear. Both additional terms are anisotropic for off-centre observers, because of to their dependence on a telescopic angle of observation. This generalized linear Hubble law could explain, in a cosmological setting, the observed large scale flow of matter, without to have recourse to peculiar velocity-type newtonian models. It is pointed out also, that the matter dipole direction should coincide with the CBR dipole one. |
gr-qc/0607033 | Ali Shojai | Fatimah Shojai and Ali Shojai | Variational Methods in Loop Quantum Cosmology | To appear in EuroPhysics Letters | Europhys.Lett. 75 (2006) 702-708 | 10.1209/epl/i2006-10166-9 | null | gr-qc | null | An action functional for the loop quantum cosmology difference equation is
presented. It is shown that by guessing the general form of the solution and
optimizing the action functional with respect to the parameters in the guessed
solution one can obtain approximate solutions which are reasonably good.
| [
{
"created": "Sun, 9 Jul 2006 08:55:11 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Shojai",
"Fatimah",
""
],
[
"Shojai",
"Ali",
""
]
] | An action functional for the loop quantum cosmology difference equation is presented. It is shown that by guessing the general form of the solution and optimizing the action functional with respect to the parameters in the guessed solution one can obtain approximate solutions which are reasonably good. |
gr-qc/0403111 | Olaf Wucknitz | Olaf Wucknitz (Universitaet Potsdam) | Sagnac effect, twin paradox and space-time topology - Time and length in
rotating systems and closed Minkowski space-times | 31 pages, 10 (mostly color) figures included. revtex4. Submitted to
Foundations of Physics | null | null | null | gr-qc astro-ph | null | We discuss the Sagnac effect in standard Minkowski coordinates and with an
alternative synchronization convention. We find that both approaches lead to
the same result without any contradictions. When applying standard coordinates
to the complete rim of the rotating disk, a time-lag has to be taken into
account which accounts for the global anisotropy. We propose a closed Minkowski
space-time as an exact equivalent to the rim of a disk, both in the rotating
and non-rotating case. In this way the Sagnac effect can be explained as being
purely topological, neglecting the radial acceleration altogether. This proves
that the rim of the disk can be treated as an inertial system. In the same
context we discuss the twin paradox and find that the standard scenario is
equivalent to an unaccelerated version in a closed space-time. The closed
topology leads to preferred frame effects which can be detected only globally.
The relation of synchronization conventions to the measurement of lengths is
discussed in the context of Ehrenfest's paradox. This leads to a confirmation
of the classical arguments by Ehrenfest and Einstein.
| [
{
"created": "Mon, 29 Mar 2004 16:50:45 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Wucknitz",
"Olaf",
"",
"Universitaet Potsdam"
]
] | We discuss the Sagnac effect in standard Minkowski coordinates and with an alternative synchronization convention. We find that both approaches lead to the same result without any contradictions. When applying standard coordinates to the complete rim of the rotating disk, a time-lag has to be taken into account which accounts for the global anisotropy. We propose a closed Minkowski space-time as an exact equivalent to the rim of a disk, both in the rotating and non-rotating case. In this way the Sagnac effect can be explained as being purely topological, neglecting the radial acceleration altogether. This proves that the rim of the disk can be treated as an inertial system. In the same context we discuss the twin paradox and find that the standard scenario is equivalent to an unaccelerated version in a closed space-time. The closed topology leads to preferred frame effects which can be detected only globally. The relation of synchronization conventions to the measurement of lengths is discussed in the context of Ehrenfest's paradox. This leads to a confirmation of the classical arguments by Ehrenfest and Einstein. |
1910.04160 | Waleed El Hanafy | W. El Hanafy and G.G.L. Nashed | Phenomenological Reconstruction of $f(T)$ Teleparallel Gravity | 16 pages, 6 figures and 3 tables. Published in Physical Review D | Phys. Rev. D 100, 083535 (2019) | 10.1103/PhysRevD.100.083535 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a novel reconstruction method of $f(T)$ teleparallel gravity from
phenomenological parameterizations of the deceleration parameter or other
alternatives. This can be used as a toolkit to produce viable modified gravity
scenarios directly related to cosmological observations. We test two
parameterizations of the deceleration parameter considered in recent
literatures in addition to one parametrization of the effective (total)
equation of state (EoS) of the universe. We use the asymptotic behaviour of the
matter density parameter as an extra constraint to identify the viable range of
the model parameters. One of the tested models shows how tiny modification can
produce viable cosmic scenarios quantitatively similar to $\Lambda$CDM but
qualitatively different whereas the dark energy (DE) sector becomes dynamical
and fully explained by modified gravity not by a cosmological constant.
| [
{
"created": "Wed, 9 Oct 2019 13:48:35 GMT",
"version": "v1"
},
{
"created": "Thu, 24 Oct 2019 10:57:14 GMT",
"version": "v2"
}
] | 2019-10-29 | [
[
"Hanafy",
"W. El",
""
],
[
"Nashed",
"G. G. L.",
""
]
] | We present a novel reconstruction method of $f(T)$ teleparallel gravity from phenomenological parameterizations of the deceleration parameter or other alternatives. This can be used as a toolkit to produce viable modified gravity scenarios directly related to cosmological observations. We test two parameterizations of the deceleration parameter considered in recent literatures in addition to one parametrization of the effective (total) equation of state (EoS) of the universe. We use the asymptotic behaviour of the matter density parameter as an extra constraint to identify the viable range of the model parameters. One of the tested models shows how tiny modification can produce viable cosmic scenarios quantitatively similar to $\Lambda$CDM but qualitatively different whereas the dark energy (DE) sector becomes dynamical and fully explained by modified gravity not by a cosmological constant. |
gr-qc/9908035 | Carey Carpenter Briggs | C. C. Briggs | A Simple Derivation of the Einstein-Maxwell Field Equations from the 2nd
Ordinary Exterior Differential of a Precursor to the Soldering Form | 5 pages | null | null | null | gr-qc | null | A simple derivation is given of the Einstein-Maxwell field equations from the
2nd ordinary exterior differential of a precursor to the soldering form for
n-dimensional differentiable manifolds having a general linear connection and
in 5-dimensional general relativity in particular.
| [
{
"created": "Wed, 11 Aug 1999 02:16:17 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Briggs",
"C. C.",
""
]
] | A simple derivation is given of the Einstein-Maxwell field equations from the 2nd ordinary exterior differential of a precursor to the soldering form for n-dimensional differentiable manifolds having a general linear connection and in 5-dimensional general relativity in particular. |
2109.09814 | Frans Pretorius | Ulf Danielsson, Luis Lehner, Frans Pretorius | Dynamics and Observational Signatures of Shell-like Black Hole Mimickers | 27 pages, 7 figures | null | 10.1103/PhysRevD.104.124011 | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | We undertake the task of studying the non-linear dynamics of quantum gravity
motivated alternatives to black holes that in the classical limit appear as
ultra-compact shells of matter. We develop a formalism that should be amenable
to numerical solution in generic situations. For a concrete model we focus on
the spherically symmetric AdS black bubble -- a shell of matter at the Buchdahl
radius separating a Schwarzschild exterior from an AdS interior. We construct a
numerical code to study the radial dynamics of and accretion onto AdS black
bubbles, with exterior matter provided by scalar fields. In doing so we develop
numerical methods that could be extended to future studies beyond spherical
symmetry. Regarding AdS black bubbles in particular, we find that the original
prescription for the internal matter fluxes needed to stabilize the black
bubble is inadequate in dynamical settings, and we propose a two parameter
generalization of the flux model to fix this. To allow for more efficient
surveys of parameter space, we develop a simpler numerical model adapted to
spherically symmetric bubble dynamics. We identify regions of parameter space
that do allow for stable black bubbles, and moreover allow control to a desired
end-state after an accretion episode. Based on these results, and evolution of
scalar fields on black bubble backgrounds, we speculate on some observational
consequences if what are currently presumed to be black holes in the universe
were actually black bubbles.
| [
{
"created": "Mon, 20 Sep 2021 19:46:24 GMT",
"version": "v1"
}
] | 2021-12-15 | [
[
"Danielsson",
"Ulf",
""
],
[
"Lehner",
"Luis",
""
],
[
"Pretorius",
"Frans",
""
]
] | We undertake the task of studying the non-linear dynamics of quantum gravity motivated alternatives to black holes that in the classical limit appear as ultra-compact shells of matter. We develop a formalism that should be amenable to numerical solution in generic situations. For a concrete model we focus on the spherically symmetric AdS black bubble -- a shell of matter at the Buchdahl radius separating a Schwarzschild exterior from an AdS interior. We construct a numerical code to study the radial dynamics of and accretion onto AdS black bubbles, with exterior matter provided by scalar fields. In doing so we develop numerical methods that could be extended to future studies beyond spherical symmetry. Regarding AdS black bubbles in particular, we find that the original prescription for the internal matter fluxes needed to stabilize the black bubble is inadequate in dynamical settings, and we propose a two parameter generalization of the flux model to fix this. To allow for more efficient surveys of parameter space, we develop a simpler numerical model adapted to spherically symmetric bubble dynamics. We identify regions of parameter space that do allow for stable black bubbles, and moreover allow control to a desired end-state after an accretion episode. Based on these results, and evolution of scalar fields on black bubble backgrounds, we speculate on some observational consequences if what are currently presumed to be black holes in the universe were actually black bubbles. |
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