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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1202.0565 | Oleg Zaslavskii | O. B. Zaslavskii | Acceleration of particles by black holes as a result of deceleration:
ultimate manifestation of kinematic nature of BSW effect | 11 pages. Misprints corrected | Phys. Lett. B 712 (2012) 161 | 10.1016/j.physletb.2012.05.009 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The recently discovered so-called BSW effect consists in the unbound growth
of the energy E_{c.m.} in the centre of mass frame of two colliding particles
near the black hole horizon. We consider a new type of the corresponding
scenario when one of two particles ("critical") remains at rest near the
horizon of the charged near-extremal black hole due to balance between the
attractive and repulsion forces. The other one hits it with a speed close to
that of light. This scenario shows in a most pronounced way the kinematic
nature of the BSW effect. In the extremal limit, one would gain formally
infinite E_{c.m.} but this does not happen since it would have require the
critical massive particle to remain at rest on the null horizon surface that is
impossible. We also discuss the BSW effect in the metric of the extremal
Reissner-Nordstr\"om black hole when the critical particle remains at rest near
the horizon.
| [
{
"created": "Thu, 2 Feb 2012 21:36:24 GMT",
"version": "v1"
},
{
"created": "Thu, 3 May 2012 08:11:31 GMT",
"version": "v2"
},
{
"created": "Sat, 19 May 2012 08:16:56 GMT",
"version": "v3"
}
] | 2015-06-04 | [
[
"Zaslavskii",
"O. B.",
""
]
] | The recently discovered so-called BSW effect consists in the unbound growth of the energy E_{c.m.} in the centre of mass frame of two colliding particles near the black hole horizon. We consider a new type of the corresponding scenario when one of two particles ("critical") remains at rest near the horizon of the charged near-extremal black hole due to balance between the attractive and repulsion forces. The other one hits it with a speed close to that of light. This scenario shows in a most pronounced way the kinematic nature of the BSW effect. In the extremal limit, one would gain formally infinite E_{c.m.} but this does not happen since it would have require the critical massive particle to remain at rest on the null horizon surface that is impossible. We also discuss the BSW effect in the metric of the extremal Reissner-Nordstr\"om black hole when the critical particle remains at rest near the horizon. |
2401.00455 | Adam Pound | Jeremy Miller, Benjamin Leather, Adam Pound, and Niels Warburton | Worldtube puncture scheme for first- and second-order self-force
calculations in the Fourier domain | 40 pages, 10 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Second-order gravitational self-force theory has recently led to the
breakthrough calculation of "first post-adiabatic" (1PA) compact-binary
waveforms~[Phys. Rev. Lett. 130, 241402 (2023)]. The computations underlying
those waveforms depend on a method of solving the perturbative second-order
Einstein equation in the Fourier domain. In this paper we present that method,
which involves dividing the domain into several regions. Different regions
utilize different time slicings and allow for the use of "punctures" to tame
sources and enforce physical boundary conditions. We demonstrate the method for
Lorenz-gauge and Teukolsky equations in the relatively simple case of
calculating parametric derivatives ("slow time derivatives") of first-order
fields, which are an essential input at second order.
| [
{
"created": "Sun, 31 Dec 2023 11:15:41 GMT",
"version": "v1"
}
] | 2024-01-02 | [
[
"Miller",
"Jeremy",
""
],
[
"Leather",
"Benjamin",
""
],
[
"Pound",
"Adam",
""
],
[
"Warburton",
"Niels",
""
]
] | Second-order gravitational self-force theory has recently led to the breakthrough calculation of "first post-adiabatic" (1PA) compact-binary waveforms~[Phys. Rev. Lett. 130, 241402 (2023)]. The computations underlying those waveforms depend on a method of solving the perturbative second-order Einstein equation in the Fourier domain. In this paper we present that method, which involves dividing the domain into several regions. Different regions utilize different time slicings and allow for the use of "punctures" to tame sources and enforce physical boundary conditions. We demonstrate the method for Lorenz-gauge and Teukolsky equations in the relatively simple case of calculating parametric derivatives ("slow time derivatives") of first-order fields, which are an essential input at second order. |
0711.3822 | Theodore A. Jacobson | Ted Jacobson | Einstein-aether gravity: theory and observational constraints | 8 pages, for proceedings of 4th Meeting on CPT and Lorentz Symmetry
(CPT 07), Bloomington, Indiana, 8-11 Aug 2007 | null | 10.1142/9789812779519_0014 | null | gr-qc astro-ph hep-ph hep-th | null | Einstein-aether theory is general relativity coupled to a dynamical unit
timelike vector field. A brief review of current theoretical understanding and
observational constraints on the four coupling parameters of the theory is
given.
| [
{
"created": "Sat, 24 Nov 2007 06:49:09 GMT",
"version": "v1"
}
] | 2016-11-09 | [
[
"Jacobson",
"Ted",
""
]
] | Einstein-aether theory is general relativity coupled to a dynamical unit timelike vector field. A brief review of current theoretical understanding and observational constraints on the four coupling parameters of the theory is given. |
2104.01982 | Vasilis Oikonomou | S.D. Odintsov, V.K. Oikonomou | Neutron Stars in Scalar-tensor Gravity with Quartic Order Scalar
Potential | Revised version, references added, AoP accepted | null | 10.1016/j.aop.2022.168839 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we investigate the effects of a non-minimally coupled quartic
order scalar model on static neutron stars, with the non-minimal coupling in
the Jordan frame being of the form $f(\phi ) = 1 + \xi\phi^2$. Particularly we
derive the Einstein frame Tolman-Oppenheimer-Volkoff equations, and by
numerically integrating them for both the interior and the exterior of the
neutron star, using a double shooting python 3 based numerical code, we extract
the masses and radii of the neutron stars evaluated finally in the Jordan
frame, along with several other related physical quantities of interest. With
regard to the equation of state for the neutron star, we use a piecewise
polytropic equation of state with the central part being Skyrme-Lyon (SLy),
Akmal-Pandharipande-Ravenhall (APR) or the Wiringa-Fiks-Fabrocini (WFF1)
equations of state. The resulting $M-R$ graphs are compatible with the
observational bounds imposed by the GW170817 event which require the radius of
a static $M\sim 1.6 M_{\odot}$ neutron star to be larger than
$R=10.68^{+15}_{-0.04}$km and the radius of a static neutron star corresponding
to the maximum mass of the star to be larger than $R=9.6^{+0.14}_{-0.03}$km.
Moreover, the WFF1 EoS, which was excluded for static neutron stars in the
context of general relativity, for the a quartic order scalar model neutron
star model provides realistic results compatible with the GW170817 event.
| [
{
"created": "Mon, 5 Apr 2021 16:16:49 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Mar 2022 00:34:10 GMT",
"version": "v2"
}
] | 2022-04-13 | [
[
"Odintsov",
"S. D.",
""
],
[
"Oikonomou",
"V. K.",
""
]
] | In this work we investigate the effects of a non-minimally coupled quartic order scalar model on static neutron stars, with the non-minimal coupling in the Jordan frame being of the form $f(\phi ) = 1 + \xi\phi^2$. Particularly we derive the Einstein frame Tolman-Oppenheimer-Volkoff equations, and by numerically integrating them for both the interior and the exterior of the neutron star, using a double shooting python 3 based numerical code, we extract the masses and radii of the neutron stars evaluated finally in the Jordan frame, along with several other related physical quantities of interest. With regard to the equation of state for the neutron star, we use a piecewise polytropic equation of state with the central part being Skyrme-Lyon (SLy), Akmal-Pandharipande-Ravenhall (APR) or the Wiringa-Fiks-Fabrocini (WFF1) equations of state. The resulting $M-R$ graphs are compatible with the observational bounds imposed by the GW170817 event which require the radius of a static $M\sim 1.6 M_{\odot}$ neutron star to be larger than $R=10.68^{+15}_{-0.04}$km and the radius of a static neutron star corresponding to the maximum mass of the star to be larger than $R=9.6^{+0.14}_{-0.03}$km. Moreover, the WFF1 EoS, which was excluded for static neutron stars in the context of general relativity, for the a quartic order scalar model neutron star model provides realistic results compatible with the GW170817 event. |
2202.14024 | F Shojai | F. Shojai, A. Sadeghi and R. Hassannejad | Generalized Oppenheimer-Snyder Gravitational Collapse into Regular Black
holes | To appear in Class. Quant. Grav | null | 10.1088/1361-6382/ac5924 | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | We shall study the formation of a particular class of regular black holes
from the gravitational collapse of a massive star. The inside geometry is
described by spatially flat Friedmann-Robertson-Walker metric and the stellar
matter is distributed uniformly without any pre-assumption about its equation
of state. Our model is a generalization of Oppenheimer-Snyder collapse for
regular black holes. We have obtained the density and pressure of star by
applying the condition of smooth joining of metrics at the freely falling
surface of star. Specifying the regular black holes to Hayward and Bardeen
cases, we see that the stellar matter is described by a polytropic equation of
state and moreover, for the radius smaller than a certain value, the strong
energy condition becomes invalid. Then for both black holes, the interior
apparent and event horizons and also the stellar surface are obtained as
functions of the proper time of star. At the end, we have constructed a new two
parametric family of regular black holes jointed smoothly to the flat
Friedmann-Robertson-Walker interior metric of a polytropic star with an
arbitrary index.
| [
{
"created": "Mon, 28 Feb 2022 18:46:53 GMT",
"version": "v1"
}
] | 2022-04-13 | [
[
"Shojai",
"F.",
""
],
[
"Sadeghi",
"A.",
""
],
[
"Hassannejad",
"R.",
""
]
] | We shall study the formation of a particular class of regular black holes from the gravitational collapse of a massive star. The inside geometry is described by spatially flat Friedmann-Robertson-Walker metric and the stellar matter is distributed uniformly without any pre-assumption about its equation of state. Our model is a generalization of Oppenheimer-Snyder collapse for regular black holes. We have obtained the density and pressure of star by applying the condition of smooth joining of metrics at the freely falling surface of star. Specifying the regular black holes to Hayward and Bardeen cases, we see that the stellar matter is described by a polytropic equation of state and moreover, for the radius smaller than a certain value, the strong energy condition becomes invalid. Then for both black holes, the interior apparent and event horizons and also the stellar surface are obtained as functions of the proper time of star. At the end, we have constructed a new two parametric family of regular black holes jointed smoothly to the flat Friedmann-Robertson-Walker interior metric of a polytropic star with an arbitrary index. |
1608.05941 | Mercedes Martin-Benito | Jer\'onimo Cortez, Beatriz Elizaga Navascu\'es, Mercedes
Mart\'in-Benito, Guillermo A. Mena Marug\'an and Jos\'e M. Velhinho | Uniqueness of the Fock quantization of Dirac fields in 2+1 dimensions | 24 pages. Document replaced to match published version | Phys. Rev. D 96, 025024 (2017) | 10.1103/PhysRevD.96.025024 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the Fock quantization of a free Dirac field in 2+1-dimensional
backgrounds which are conformally ultrastatic, with a time-dependent conformal
factor. As it is typical for field theories, there is an infinite ambiguity in
the Fock representation of the canonical anticommutation relations. Different
choices may lead to unitarily inequivalent theories that describe different
physics. To remove this ambiguity one usually requires that the vacuum be
invariant under the unitary transformations that implement the symmetries of
the equations of motion. However, in non-stationary backgrounds, where time
translation is not a symmetry transformation, the requirement of vacuum
invariance is in general not enough to fix completely the Fock representation.
We show that this problem is overcome in the considered scenario by demanding,
in addition, a unitarily implementable quantum dynamics. The combined
imposition of these conditions selects a unique family of equivalent Fock
representations. Moreover, one also obtains an essentially unique splitting of
the time variation of the Dirac field into an explicit dependence on the
background scale factor and a quantum evolution of the corresponding creation
and annihilation operators.
| [
{
"created": "Sun, 21 Aug 2016 14:06:18 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Sep 2017 11:08:35 GMT",
"version": "v2"
}
] | 2017-09-06 | [
[
"Cortez",
"Jerónimo",
""
],
[
"Navascués",
"Beatriz Elizaga",
""
],
[
"Martín-Benito",
"Mercedes",
""
],
[
"Marugán",
"Guillermo A. Mena",
""
],
[
"Velhinho",
"José M.",
""
]
] | We study the Fock quantization of a free Dirac field in 2+1-dimensional backgrounds which are conformally ultrastatic, with a time-dependent conformal factor. As it is typical for field theories, there is an infinite ambiguity in the Fock representation of the canonical anticommutation relations. Different choices may lead to unitarily inequivalent theories that describe different physics. To remove this ambiguity one usually requires that the vacuum be invariant under the unitary transformations that implement the symmetries of the equations of motion. However, in non-stationary backgrounds, where time translation is not a symmetry transformation, the requirement of vacuum invariance is in general not enough to fix completely the Fock representation. We show that this problem is overcome in the considered scenario by demanding, in addition, a unitarily implementable quantum dynamics. The combined imposition of these conditions selects a unique family of equivalent Fock representations. Moreover, one also obtains an essentially unique splitting of the time variation of the Dirac field into an explicit dependence on the background scale factor and a quantum evolution of the corresponding creation and annihilation operators. |
2201.10104 | LSC P&P Committee | The LIGO Scientific Collaboration, the Virgo Collaboration, and the
KAGRA Collaboration: R. Abbott, H. Abe, F. Acernese, K. Ackley, N. Adhikari,
R. X. Adhikari, V. K. Adkins, V. B. Adya, C. Affeldt, D. Agarwal, M. Agathos,
K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, T.
Akutsu, S. Albanesi, R. A. Alfaidi, A. Allocca, P. A. Altin, A. Amato, C.
Anand, S. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Ando, T.
Andrade, N. Andres, M. Andr\'es-Carcasona, T. Andri\'c, S. V. Angelova, S.
Ansoldi, J. M. Antelis, S. Antier, T. Apostolatos, E. Z. Appavuravther, S.
Appert, S. K. Apple, K. Arai, A. Araya, M. C. Araya, J. S. Areeda, M.
Ar\`ene, N. Aritomi, N. Arnaud, M. Arogeti, S. M. Aronson, H. Asada, Y.
Asali, G. Ashton, Y. Aso, M. Assiduo, S. Assis de Souza Melo, S. M. Aston, P.
Astone, F. Aubin, K. AultONeal, C. Austin, S. Babak, F. Badaracco, M. K. M.
Bader, C. Badger, S. Bae, Y. Bae, A. M. Baer, S. Bagnasco, Y. Bai, J. Baird,
R. Bajpai, T. Baka, M. Ball, G. Ballardin, S. W. Ballmer, A. Balsamo, G.
Baltus, S. Banagiri, B. Banerjee, D. Bankar, J. C. Barayoga, C. Barbieri, B.
C. Barish, D. Barker, P. Barneo, F. Barone, B. Barr, L. Barsotti, M.
Barsuglia, D. Barta, J. Bartlett, M. A. Barton, I. Bartos, S. Basak, R.
Bassiri, A. Basti, M. Bawaj, J. C. Bayley, M. Bazzan, B. R. Becher, B.
B\'ecsy, V. M. Bedakihale, F. Beirnaert, M. Bejger, I. Belahcene, V.
Benedetto, D. Beniwal, M. G. Benjamin, T. F. Bennett, J. D. Bentley, M.
BenYaala, S. Bera, M. Berbel, F. Bergamin, B. K. Berger, S. Bernuzzi, D.
Bersanetti, A. Bertolini, J. Betzwieser, D. Beveridge, R. Bhandare, A. V.
Bhandari, U. Bhardwaj, R. Bhatt, D. Bhattacharjee, S. Bhaumik, A. Bianchi, I.
A. Bilenko, G. Billingsley, S. Bini, R. Birney, O. Birnholtz, S. Biscans, M.
Bischi, S. Biscoveanu, A. Bisht, B. Biswas, M. Bitossi, M.-A. Bizouard, J. K.
Blackburn, C. D. Blair, D. G. Blair, R. M. Blair, F. Bobba, N. Bode, M.
Bo\"er, G. Bogaert, M. Boldrini, G. N. Bolingbroke, L. D. Bonavena, F. Bondu,
E. Bonilla, R. Bonnand, P. Booker, B. A. Boom, R. Bork, V. Boschi, N. Bose,
S. Bose, V. Bossilkov, V. Boudart, Y. Bouffanais, A. Bozzi, C. Bradaschia, P.
R. Brady, A. Bramley, A. Branch, M. Branchesi, J. E. Brau, M. Breschi, T.
Briant, J. H. Briggs, A. Brillet, M. Brinkmann, P. Brockill, A. F. Brooks, J.
Brooks, D. D. Brown, S. Brunett, G. Bruno, R. Bruntz, J. Bryant, F. Bucci, T.
Bulik, H. J. Bulten, A. Buonanno, K. Burtnyk, R. Buscicchio, D. Buskulic, C.
Buy, R. L. Byer, G. S. Cabourn Davies, G. Cabras, R. Cabrita, L. Cadonati, M.
Caesar, G. Cagnoli, C. Cahillane, J. Calder\'on Bustillo, J. D. Callaghan, T.
A. Callister, E. Calloni, J. Cameron, J. B. Camp, M. Canepa, S. Canevarolo,
M. Cannavacciuolo, K. C. Cannon, H. Cao, Z. Cao, E. Capocasa, E. Capote, G.
Carapella, F. Carbognani, M. Carlassara, J. B. Carlin, M. F. Carney, M.
Carpinelli, G. Carrillo, G. Carullo, T. L. Carver, J. Casanueva Diaz, C.
Casentini, G. Castaldi, S. Caudill, M. Cavagli\`a, F. Cavalier, R. Cavalieri,
G. Cella, P. Cerd\'a-Dur\'an, E. Cesarini, W. Chaibi, S. Chalathadka
Subrahmanya, E. Champion, C.-H. Chan, C. Chan, C. L. Chan, K. Chan, M. Chan,
K. Chandra, I. P. Chang, P. Chanial, S. Chao, C. Chapman-Bird, P. Charlton,
E. A. Chase, E. Chassande-Mottin, C. Chatterjee, Debarati Chatterjee, Deep
Chatterjee, M. Chaturvedi, S. Chaty, C. Chen, D. Chen, H. Y. Chen, J. Chen,
K. Chen, X. Chen, Y.-B. Chen, Y.-R. Chen, Z. Chen, H. Cheng, C. K. Cheong, H.
Y. Cheung, H. Y. Chia, F. Chiadini, C-Y. Chiang, G. Chiarini, R. Chierici, A.
Chincarini, M. L. Chiofalo, A. Chiummo, R. K. Choudhary, S. Choudhary, N.
Christensen, Q. Chu, Y-K. Chu, S. S. Y. Chua, K. W. Chung, G. Ciani, P.
Ciecielag, M. Cie\'slar, M. Cifaldi, A. A. Ciobanu, R. Ciolfi, F. Cipriano,
F. Clara, J. A. Clark, P. Clearwater, S. Clesse, F. Cleva, E. Coccia, E.
Codazzo, P.-F. Cohadon, D. E. Cohen, M. Colleoni, C. G. Collette, A. Colombo,
M. Colpi, C. M. Compton, M. Constancio Jr., L. Conti, S. J. Cooper, P.
Corban, T. R. Corbitt, I. Cordero-Carri\'on, S. Corezzi, K. R. Corley, N. J.
Cornish, D. Corre, A. Corsi, S. Cortese, C. A. Costa, R. Cotesta, R.
Cottingham, M. W. Coughlin, J.-P. Coulon, S. T. Countryman, B. Cousins, P.
Couvares, D. M. Coward, M. J. Cowart, D. C. Coyne, R. Coyne, J. D. E.
Creighton, T. D. Creighton, A. W. Criswell, M. Croquette, S. G. Crowder, J.
R. Cudell, T. J. Cullen, A. Cumming, R. Cummings, L. Cunningham, E. Cuoco, M.
Cury{\l}o, P. Dabadie, T. Dal Canton, S. Dall'Osso, G. D\'alya, A. Dana, B.
D'Angelo, S. Danilishin, S. D'Antonio, K. Danzmann, C. Darsow-Fromm, A.
Dasgupta, L. E. H. Datrier, Sayak Datta, Sayantani Datta, V. Dattilo, I.
Dave, M. Davier, D. Davis, M. C. Davis, E. J. Daw, R. Dean, D. DeBra, M.
Deenadayalan, J. Degallaix, M. De Laurentis, S. Del\'eglise, V. Del Favero,
F. De Lillo, N. De Lillo, D. Dell'Aquila, W. Del Pozzo, L. M. DeMarchi, F. De
Matteis, V. D'Emilio, N. Demos, T. Dent, A. Depasse, R. De Pietri, R. De
Rosa, C. De Rossi, R. DeSalvo, R. De Simone, S. Dhurandhar, M. C. D\'iaz, N.
A. Didio, T. Dietrich, L. Di Fiore, C. Di Fronzo, C. Di Giorgio, F. Di
Giovanni, M. Di Giovanni, T. Di Girolamo, A. Di Lieto, A. Di Michele, B.
Ding, S. Di Pace, I. Di Palma, F. Di Renzo, A. K. Divakarla, A. Dmitriev, Z.
Doctor, L. Donahue, L. D'Onofrio, F. Donovan, K. L. Dooley, S. Doravari, M.
Drago, J. C. Driggers, Y. Drori, J.-G. Ducoin, P. Dupej, U. Dupletsa, O.
Durante, D. D'Urso, P.-A. Duverne, S. E. Dwyer, C. Eassa, P. J. Easter, M.
Ebersold, T. Eckhardt, G. Eddolls, B. Edelman, T. B. Edo, O. Edy, A. Effler,
S. Eguchi, J. Eichholz, S. S. Eikenberry, M. Eisenmann, R. A. Eisenstein, A.
Ejlli, E. Engelby, Y. Enomoto, L. Errico, R. C. Essick, H. Estell\'es, D.
Estevez, Z. Etienne, T. Etzel, M. Evans, T. M. Evans, T. Evstafyeva, B. E.
Ewing, F. Fabrizi, F. Faedi, V. Fafone, H. Fair, S. Fairhurst, P. C. Fan, A.
M. Farah, S. Farinon, B. Farr, W. M. Farr, E. J. Fauchon-Jones, G. Favaro, M.
Favata, M. Fays, M. Fazio, J. Feicht, M. M. Fejer, E. Fenyvesi, D. L.
Ferguson, A. Fernandez-Galiana, I. Ferrante, T. A. Ferreira, F. Fidecaro, P.
Figura, A. Fiori, I. Fiori, M. Fishbach, R. P. Fisher, R. Fittipaldi, V.
Fiumara, R. Flaminio, E. Floden, H. K. Fong, J. A. Font, B. Fornal, P. W. F.
Forsyth, A. Franke, S. Frasca, F. Frasconi, J. P. Freed, Z. Frei, A. Freise,
O. Freitas, R. Frey, P. Fritschel, V. V. Frolov, G. G. Fronz\'e, Y. Fujii, Y.
Fujikawa, Y. Fujimoto, P. Fulda, M. Fyffe, H. A. Gabbard, W. E. Gabella, B.
U. Gadre, J. R. Gair, J. Gais, S. Galaudage, R. Gamba, D. Ganapathy, A.
Ganguly, D. Gao, S. G. Gaonkar, B. Garaventa, C. Garc\'ia N\'u\~nez, C.
Garc\'ia-Quir\'os, F. Garufi, B. Gateley, V. Gayathri, G.-G. Ge, G. Gemme, A.
Gennai, J. George, O. Gerberding, L. Gergely, P. Gewecke, S. Ghonge, Abhirup
Ghosh, Archisman Ghosh, Shaon Ghosh, Shrobana Ghosh, Tathagata Ghosh, B.
Giacomazzo, L. Giacoppo, J. A. Giaime, K. D. Giardina, D. R. Gibson, C. Gier,
M. Giesler, P. Giri, F. Gissi, S. Gkaitatzis, J. Glanzer, A. E. Gleckl, P.
Godwin, E. Goetz, R. Goetz, N. Gohlke, J. Golomb, B. Goncharov, G.
Gonz\'alez, M. Gosselin, R. Gouaty, D. W. Gould, S. Goyal, B. Grace, A.
Grado, V. Graham, M. Granata, V. Granata, A. Grant, S. Gras, P. Grassia, C.
Gray, R. Gray, G. Greco, A. C. Green, R. Green, A. M. Gretarsson, E. M.
Gretarsson, D. Griffith, W. L. Griffiths, H. L. Griggs, G. Grignani, A.
Grimaldi, E. Grimes, S. J. Grimm, H. Grote, S. Grunewald, P. Gruning, A. S.
Gruson, D. Guerra, G. M. Guidi, A. R. Guimaraes, G. Guix\'e, H. K. Gulati, A.
M. Gunny, H.-K. Guo, Y. Guo, Anchal Gupta, Anuradha Gupta, I. M. Gupta, P.
Gupta, S. K. Gupta, R. Gustafson, F. Guzman, S. Ha, I. P. W. Hadiputrawan, L.
Haegel, S. Haino, O. Halim, E. D. Hall, E. Z. Hamilton, G. Hammond, W.-B.
Han, M. Haney, J. Hanks, C. Hanna, M. D. Hannam, O. Hannuksela, H. Hansen, T.
J. Hansen, J. Hanson, T. Harder, K. Haris, J. Harms, G. M. Harry, I. W.
Harry, D. Hartwig, K. Hasegawa, B. Haskell, C.-J. Haster, J. S. Hathaway, K.
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Zweizig | Search for gravitational waves from Scorpius X-1 with a hidden Markov
model in O3 LIGO data | 23 pages, 5 figures | null | 10.1103/PhysRevD.106.062002 | LIGO-P2100405 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Results are presented for a semi-coherent search for continuous gravitational
waves from the low-mass X-ray binary Scorpius X-1, using a hidden Markov model
(HMM) to allow for spin wandering. This search improves on previous HMM-based
searches of Laser Interferometer Gravitational-wave Observatory (LIGO) data by
including the orbital period in the search template grid, and by analyzing data
from the latest (third) observing run (O3). In the frequency range searched,
from 60 to 500 Hz, we find no evidence of gravitational radiation. This is the
most sensitive search for Scorpius X-1 using a HMM to date. For the most
sensitive sub-band, starting at $256.06$Hz, we report an upper limit on
gravitational wave strain (at $95 \%$ confidence) of
$h_{0}^{95\%}=6.16\times10^{-26}$, assuming the orbital inclination angle takes
its electromagnetically restricted value $\iota=44^{\circ}$. The upper limits
on gravitational wave strain reported here are on average a factor of $\sim 3$
lower than in the O2 HMM search. This is the first Scorpius X-1 HMM search with
upper limits that reach below the indirect torque-balance limit for certain
sub-bands, assuming $\iota=44^{\circ}$.
| [
{
"created": "Tue, 25 Jan 2022 05:45:43 GMT",
"version": "v1"
}
] | 2023-02-01 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"the KAGRA Collaboration",
"",
""
],
[
"Abbott",
"R.",
""
],
[
"Abe",
"H.",
""
],
[
"Acernese",
"F.",
""
],
[
"Ackley",
"K... | Results are presented for a semi-coherent search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1, using a hidden Markov model (HMM) to allow for spin wandering. This search improves on previous HMM-based searches of Laser Interferometer Gravitational-wave Observatory (LIGO) data by including the orbital period in the search template grid, and by analyzing data from the latest (third) observing run (O3). In the frequency range searched, from 60 to 500 Hz, we find no evidence of gravitational radiation. This is the most sensitive search for Scorpius X-1 using a HMM to date. For the most sensitive sub-band, starting at $256.06$Hz, we report an upper limit on gravitational wave strain (at $95 \%$ confidence) of $h_{0}^{95\%}=6.16\times10^{-26}$, assuming the orbital inclination angle takes its electromagnetically restricted value $\iota=44^{\circ}$. The upper limits on gravitational wave strain reported here are on average a factor of $\sim 3$ lower than in the O2 HMM search. This is the first Scorpius X-1 HMM search with upper limits that reach below the indirect torque-balance limit for certain sub-bands, assuming $\iota=44^{\circ}$. |
gr-qc/0101061 | Martin Bojowald | M. Bojowald and H. A. Kastrup | Symmetric States in Quantum Geometry | 9 pages, talk at the Ninth Marcel Grossmann Meeting, Rome, July 2-8,
2000 | null | 10.1142/9789812777386_0216 | null | gr-qc | null | Symmetric states are defined in the kinematical sector of loop quantum
gravity and applied to spherical symmetry and homogeneity. Consequences for the
physics of black holes and cosmology are discussed.
| [
{
"created": "Tue, 16 Jan 2001 16:45:39 GMT",
"version": "v1"
}
] | 2017-08-23 | [
[
"Bojowald",
"M.",
""
],
[
"Kastrup",
"H. A.",
""
]
] | Symmetric states are defined in the kinematical sector of loop quantum gravity and applied to spherical symmetry and homogeneity. Consequences for the physics of black holes and cosmology are discussed. |
2404.01970 | Ayan Banerjee | Takol Tangphati, Izzet Sakalli, Ayan Banerjee and Anirudh Pradhan | Anisotropic quark stars in $f(R,L_m,T)$ gravity | 11 pages, 7 figures, References updated | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the impact of $f(R,L_m,T)$ gravity on the internal structure
of compact stars, expecting this theory to manifest prominently in the
high-density cores of such stars. In this study, we begin by considering the
algebraic function $f(R,L_m,T) = R + \alpha T L_m$, where $\alpha$ represents
the matter-geometry coupling constant. We specifically choose the matter
Lagrangian density $L_m= -\rho$ to explore compact stars with anisotropic
pressure. To this end, we employ the MIT bag model as an equation of state. We
then numerically solve the hydrostatic equilibrium equations to obtain
mass-radius relations for quark stars, examining static stability criteria, the
adiabatic index, and the speed of sound. Finally, we use recent astrophysical
data to constrain the coupling parameter $\alpha$, which may lead to either
larger or smaller masses for quark stars compared to their counterparts in
general relativity.
| [
{
"created": "Tue, 2 Apr 2024 14:14:04 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Apr 2024 14:06:23 GMT",
"version": "v2"
}
] | 2024-04-11 | [
[
"Tangphati",
"Takol",
""
],
[
"Sakalli",
"Izzet",
""
],
[
"Banerjee",
"Ayan",
""
],
[
"Pradhan",
"Anirudh",
""
]
] | We investigate the impact of $f(R,L_m,T)$ gravity on the internal structure of compact stars, expecting this theory to manifest prominently in the high-density cores of such stars. In this study, we begin by considering the algebraic function $f(R,L_m,T) = R + \alpha T L_m$, where $\alpha$ represents the matter-geometry coupling constant. We specifically choose the matter Lagrangian density $L_m= -\rho$ to explore compact stars with anisotropic pressure. To this end, we employ the MIT bag model as an equation of state. We then numerically solve the hydrostatic equilibrium equations to obtain mass-radius relations for quark stars, examining static stability criteria, the adiabatic index, and the speed of sound. Finally, we use recent astrophysical data to constrain the coupling parameter $\alpha$, which may lead to either larger or smaller masses for quark stars compared to their counterparts in general relativity. |
1708.00441 | Omar Roldan | Omar Roldan | CMB in the river frame and gauge invariance at second order | 29 pages, 2 figures, references added, sec. 2.1 enhanced, appendix B
added, published in JCAP | JCAP 1803 (2018) no.03, 014 | 10.1088/1475-7516/2018/03/014 | null | gr-qc astro-ph.CO astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | GAUGE INVARIANCE: The Sachs-Wolfe formula describing the Cosmic Microwave
Background (CMB) temperature anisotropies is one of the most important
relations in cosmology. Despite its importance, the gauge invariance of this
formula has only been discussed at first order. Here we discuss the subtle
issue of second-order gauge transformations on the CMB. By introducing two
rules (needed to handle the subtle issues), we prove the gauge invariance of
the second-order Sachs-Wolfe formula and provide several compact expressions
which can be useful for the study of gauge transformations on cosmology. Our
results go beyond a simple technicality: we discuss from a physical point of
view several aspects that improve our understanding of the CMB. We also
elucidate how crucial it is to understand gauge transformations on the CMB in
order to avoid errors and/or misconceptions as occurred in the past. THE RIVER
FRAME: we introduce a cosmological frame which we call the river frame. In this
frame, photons and any object can be thought as fishes swimming in the river
and relations are easily expressed in either the metric or the covariant
formalism then ensuring a transparent geometric meaning. Finally, our results
show that the river frame is useful to make perturbative and non-perturbative
analysis. In particular, it was already used to obtain the fully nonlinear
generalization of the Sachs-Wolfe formula and is used here to describe
second-order perturbations.
| [
{
"created": "Tue, 1 Aug 2017 15:36:37 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Aug 2017 12:40:02 GMT",
"version": "v2"
},
{
"created": "Sun, 22 Apr 2018 02:06:16 GMT",
"version": "v3"
}
] | 2018-04-24 | [
[
"Roldan",
"Omar",
""
]
] | GAUGE INVARIANCE: The Sachs-Wolfe formula describing the Cosmic Microwave Background (CMB) temperature anisotropies is one of the most important relations in cosmology. Despite its importance, the gauge invariance of this formula has only been discussed at first order. Here we discuss the subtle issue of second-order gauge transformations on the CMB. By introducing two rules (needed to handle the subtle issues), we prove the gauge invariance of the second-order Sachs-Wolfe formula and provide several compact expressions which can be useful for the study of gauge transformations on cosmology. Our results go beyond a simple technicality: we discuss from a physical point of view several aspects that improve our understanding of the CMB. We also elucidate how crucial it is to understand gauge transformations on the CMB in order to avoid errors and/or misconceptions as occurred in the past. THE RIVER FRAME: we introduce a cosmological frame which we call the river frame. In this frame, photons and any object can be thought as fishes swimming in the river and relations are easily expressed in either the metric or the covariant formalism then ensuring a transparent geometric meaning. Finally, our results show that the river frame is useful to make perturbative and non-perturbative analysis. In particular, it was already used to obtain the fully nonlinear generalization of the Sachs-Wolfe formula and is used here to describe second-order perturbations. |
2204.03259 | Mehrab Momennia | Mehrab Momennia | Quasinormal modes of self-dual black holes in loop quantum gravity | 15 pages, 6 captioned figures, and 16 tables. Comments are welcome;
V2: Minor changes to match published version, references added | Phys. Rev. D 106, 024052 (2022) | 10.1103/PhysRevD.106.024052 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We study the evolution of a test scalar field on the background geometry of a
regular loop quantum black hole (LQBH) characterized by two loop quantum
gravity (LQG) correction parameters, namely, the polymeric function and the
minimum area gap. The calculations of quasinormal frequencies in asymptotically
flat spacetime are performed with the help of higher-order WKB expansion and
related Pad\'{e} approximants, the improved asymptotic iteration method (AIM),
and time-domain integration. The effects of free parameters of the theory on
the quasinormal modes are studied and deviations from those of the
Schwarzschild BHs are investigated. We show that the LQG correction parameters
have opposite effects on the quasinormal frequencies and the LQBHs are
dynamically stable.
| [
{
"created": "Thu, 7 Apr 2022 07:12:06 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Aug 2022 23:23:12 GMT",
"version": "v2"
}
] | 2022-08-09 | [
[
"Momennia",
"Mehrab",
""
]
] | We study the evolution of a test scalar field on the background geometry of a regular loop quantum black hole (LQBH) characterized by two loop quantum gravity (LQG) correction parameters, namely, the polymeric function and the minimum area gap. The calculations of quasinormal frequencies in asymptotically flat spacetime are performed with the help of higher-order WKB expansion and related Pad\'{e} approximants, the improved asymptotic iteration method (AIM), and time-domain integration. The effects of free parameters of the theory on the quasinormal modes are studied and deviations from those of the Schwarzschild BHs are investigated. We show that the LQG correction parameters have opposite effects on the quasinormal frequencies and the LQBHs are dynamically stable. |
gr-qc/0512072 | Daniel R. Terno | Daniel R. Terno | Quantum information in loop quantum gravity | RevTex, 5 pages. Proceedings of QG'05, Cala Gonone, 2005 Relations of
the coarse-graining and partial tracing are clarified, and the references are
updated | J.Phys.Conf.Ser. 33 (2006) 469-474 | 10.1088/1742-6596/33/1/061 | null | gr-qc quant-ph | null | A coarse-graining of spin networks is expressed in terms of partial tracing,
thus allowing to use tools of quantum information theory. This is illustrated
by the analysis of a simple black hole model, where the logarithmic correction
of the Bekenstein-Hawking entropy is shown to be equal to the total amount of
correlations on the horizon. Finally other applications of entanglement to
quantum gravity are briefly discussed.
| [
{
"created": "Mon, 12 Dec 2005 22:35:37 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Mar 2006 15:32:25 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Terno",
"Daniel R.",
""
]
] | A coarse-graining of spin networks is expressed in terms of partial tracing, thus allowing to use tools of quantum information theory. This is illustrated by the analysis of a simple black hole model, where the logarithmic correction of the Bekenstein-Hawking entropy is shown to be equal to the total amount of correlations on the horizon. Finally other applications of entanglement to quantum gravity are briefly discussed. |
1304.5411 | Diego S\'aez-G\'omez | Sergei D. Odintsov, Diego S\'aez-G\'omez | f(R, T, R_\mu\nu T^\mu\nu) gravity phenomenology and \Lambda CDM
universe | 12 pages. Analysis extended and minor corrections. Version published
in PLB | Phys. Lett. B 725 (2013) 437-444 | 10.1016/j.physletb.2013.07.026 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose general f(R,T,R_{\mu\nu}T^{\mu\nu}) theory as generalization of
covariant Horava-like gravity with dynamical Lorentz symmetry breaking. FRLW
cosmological dynamics for several versions of such theory is considered. The
reconstruction of the above action is explicitly done, including the numerical
reconstruction for the occurrence of \Lambda CDM universe. De Sitter universe
solutions in the presence of non-constant fluid are also presented. The problem
of matter instability in f(R,T,R_{\mu\nu}T^{\mu\nu}) gravity is discussed.
| [
{
"created": "Fri, 19 Apr 2013 13:26:40 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Jul 2013 14:58:07 GMT",
"version": "v2"
},
{
"created": "Thu, 5 Sep 2013 14:46:08 GMT",
"version": "v3"
}
] | 2015-06-15 | [
[
"Odintsov",
"Sergei D.",
""
],
[
"Sáez-Gómez",
"Diego",
""
]
] | We propose general f(R,T,R_{\mu\nu}T^{\mu\nu}) theory as generalization of covariant Horava-like gravity with dynamical Lorentz symmetry breaking. FRLW cosmological dynamics for several versions of such theory is considered. The reconstruction of the above action is explicitly done, including the numerical reconstruction for the occurrence of \Lambda CDM universe. De Sitter universe solutions in the presence of non-constant fluid are also presented. The problem of matter instability in f(R,T,R_{\mu\nu}T^{\mu\nu}) gravity is discussed. |
gr-qc/9810032 | Ilya Shapiro | J.C. Fabris, A.M. Pelinson, I.L. Shapiro | Anomaly-induced effective action for gravity and inflation | LaTeX, 12 pages, 4 figures, Some mistakes and misprints in formulas
and Figures corrected | Grav.Cosmol. 6 (2000) 59-65 | null | DF/UFJF-5 | gr-qc hep-th | null | In the very early Universe the matter may be described by the free radiation,
that is by the set of massless fields with negligible interactions between
them. Then the dominating quantum effect is the trace anomaly which comes from
the renormalization of the conformal invariant part of the vacuum action. The
anomaly-induced effective action can be found with accuracy to an arbitrary
conformal functional which vanishes for the special case of the conformally
flat metric. This gives the solid basis for the study of the conformally-flat
cosmological solutions, first of which was discovered by Mamaev and
Mostepanenko and by Starobinski in 1980. Treating the anomaly-induced action as
quantum correction to the Einstein-Hilbert term we explore the possibility to
have inflationary solutions, investigate their dependence on the initial data
and discuss the restrictions in considering the density perturbations. The
shape of inflationary solutions strongly depends on the underlying gauge model
of the elementary particles physics. Two special cases are considered: Minimal
Standard Model and the matter sector of N=8, D=4 supergravity. It turns out
that inflation is almost inevitable consequence of the great difference between
Planck mass and the mass of the heaviest massive particle.
| [
{
"created": "Thu, 8 Oct 1998 21:26:15 GMT",
"version": "v1"
},
{
"created": "Sat, 10 Oct 1998 14:19:30 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Fabris",
"J. C.",
""
],
[
"Pelinson",
"A. M.",
""
],
[
"Shapiro",
"I. L.",
""
]
] | In the very early Universe the matter may be described by the free radiation, that is by the set of massless fields with negligible interactions between them. Then the dominating quantum effect is the trace anomaly which comes from the renormalization of the conformal invariant part of the vacuum action. The anomaly-induced effective action can be found with accuracy to an arbitrary conformal functional which vanishes for the special case of the conformally flat metric. This gives the solid basis for the study of the conformally-flat cosmological solutions, first of which was discovered by Mamaev and Mostepanenko and by Starobinski in 1980. Treating the anomaly-induced action as quantum correction to the Einstein-Hilbert term we explore the possibility to have inflationary solutions, investigate their dependence on the initial data and discuss the restrictions in considering the density perturbations. The shape of inflationary solutions strongly depends on the underlying gauge model of the elementary particles physics. Two special cases are considered: Minimal Standard Model and the matter sector of N=8, D=4 supergravity. It turns out that inflation is almost inevitable consequence of the great difference between Planck mass and the mass of the heaviest massive particle. |
1302.1644 | Ali Reza Amani | Ali R. Amani, Celia Escamilla-Rivera and H. R. Faghani | Interacting closed string tachyon with modified Chaplygin gas and its
stability | 14 pages, 9 figures, Accepted by Phys.Rev.D | Phys. Rev. D 88, 124008 (2013) | 10.1103/PhysRevD.88.124008 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we have considered closed string tachyon model with a constant
dilaton field and interacted it with Chaplygin gas for evaluating cosmology
parameters. The model has been studied in $26$-dimensional that its
$22$-dimensional is related to compactification on an internal non-flat space
and its other $4$-dimensions is related to FLRW metric. By taking the internal
curvature as a negative constant, we obtained the closed string tachyon
potential as a quartic equation. The tachyon field and the scale factor have
been achieved as functional of time evolution and geometry of curved space
where the behaviour of the scale factor describes an accelerated expansion of
the universe. Next, we discussed the stability of our model by introducing a
sound speed factor, which one must be, in our case, a positive function. By
drawing sound speed against time evolution we investigated stability conditions
for non-flat universe in its three stages: early, late and future time. As a
result we shall see that in these cases remains an instability at early time
and a stability point at late time.
| [
{
"created": "Thu, 7 Feb 2013 05:17:13 GMT",
"version": "v1"
},
{
"created": "Sat, 16 Nov 2013 16:41:55 GMT",
"version": "v2"
}
] | 2013-12-16 | [
[
"Amani",
"Ali R.",
""
],
[
"Escamilla-Rivera",
"Celia",
""
],
[
"Faghani",
"H. R.",
""
]
] | In this paper, we have considered closed string tachyon model with a constant dilaton field and interacted it with Chaplygin gas for evaluating cosmology parameters. The model has been studied in $26$-dimensional that its $22$-dimensional is related to compactification on an internal non-flat space and its other $4$-dimensions is related to FLRW metric. By taking the internal curvature as a negative constant, we obtained the closed string tachyon potential as a quartic equation. The tachyon field and the scale factor have been achieved as functional of time evolution and geometry of curved space where the behaviour of the scale factor describes an accelerated expansion of the universe. Next, we discussed the stability of our model by introducing a sound speed factor, which one must be, in our case, a positive function. By drawing sound speed against time evolution we investigated stability conditions for non-flat universe in its three stages: early, late and future time. As a result we shall see that in these cases remains an instability at early time and a stability point at late time. |
0807.3077 | Joseph Katz | Donald Lynden-Bell, Jiri Bicak and Joseph Katz | Inertial frame rotation induced by rotating gravitational waves | Scheduled to appear in Class. and Quantum Grav. July 2008, "inertial"
added in title | Class. Quantum Grav. 25 (2008) 165018 | 10.1088/0264-9381/25/16/165018 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We calculate the rotation of the inertial frames within an almost flat
cylindrical region surrounded by a pulse of non-axially-symmetric gravitational
waves that rotate about the axis of our cylindrical polar coordinates. Our
spacetime has only one Killing vector. It is along the z-axis and hypersurface
orthogonal. We solve the Einstein equations to first order in the wave
amplitude and superpose such linearized solutions to form a wave pulse. We then
solve the relevant Einstein equation to second order in the amplitude to find
the rotation of inertial frames produced by the pulse. The rotation is without
time delay. The influence of gravitational wave angular momentum on the
inertial frame demonstrates that Mach's principle can not be expressed in terms
of the influence of the stress-energy-momentum tensor alone but must involve
also influences of gravitational wave energy and angular momentum.
| [
{
"created": "Sat, 19 Jul 2008 10:11:35 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Aug 2008 06:41:01 GMT",
"version": "v2"
}
] | 2009-11-13 | [
[
"Lynden-Bell",
"Donald",
""
],
[
"Bicak",
"Jiri",
""
],
[
"Katz",
"Joseph",
""
]
] | We calculate the rotation of the inertial frames within an almost flat cylindrical region surrounded by a pulse of non-axially-symmetric gravitational waves that rotate about the axis of our cylindrical polar coordinates. Our spacetime has only one Killing vector. It is along the z-axis and hypersurface orthogonal. We solve the Einstein equations to first order in the wave amplitude and superpose such linearized solutions to form a wave pulse. We then solve the relevant Einstein equation to second order in the amplitude to find the rotation of inertial frames produced by the pulse. The rotation is without time delay. The influence of gravitational wave angular momentum on the inertial frame demonstrates that Mach's principle can not be expressed in terms of the influence of the stress-energy-momentum tensor alone but must involve also influences of gravitational wave energy and angular momentum. |
gr-qc/9307027 | null | Antonio Campos and Enric Verdaguer | Semiclassical Equations for Weakly Inhomogeneous Cosmologies | 35 pages, UAB-FT 316, Latex (uses a4wide.sty, a4.sty included in the
file)(replaced due to tex problems) | Phys.Rev.D49:1861-1880,1994 | 10.1103/PhysRevD.49.1861 | null | gr-qc | null | The in-in effective action formalism is used to derive the semiclassical
correction to Einstein's equations due to a massless scalar quantum field
conformally coupled to small gravitational perturbations in spatially flat
cosmological models. The vacuum expectation value of the stress tensor of the
quantum field is directly derived from the renormalized in-in effective action.
The usual in-out effective action is also discussed and it is used to compute
the probability of particle creation. As one application, the stress tensor of
a scalar field around a static cosmic string is derived and the backreaction
effect on the gravitational field of the string is discussed.
| [
{
"created": "Wed, 21 Jul 1993 16:40:23 GMT",
"version": "v1"
}
] | 2009-07-10 | [
[
"Campos",
"Antonio",
""
],
[
"Verdaguer",
"Enric",
""
]
] | The in-in effective action formalism is used to derive the semiclassical correction to Einstein's equations due to a massless scalar quantum field conformally coupled to small gravitational perturbations in spatially flat cosmological models. The vacuum expectation value of the stress tensor of the quantum field is directly derived from the renormalized in-in effective action. The usual in-out effective action is also discussed and it is used to compute the probability of particle creation. As one application, the stress tensor of a scalar field around a static cosmic string is derived and the backreaction effect on the gravitational field of the string is discussed. |
gr-qc/9604046 | Sanjay Jhingan | Sanjay Jhingan, P. S. Joshi and T. P. Singh | The final fate of spherical inhomogeneous dust collapse II: Initial data
and causal structure of singularity | Latex file, uses epsf.sty, 15 pages and 3 eps figures. Paragraph on
role of smooth functions rewritten. Four references added. To appear in
Classical & Quantum Gravity | Class.Quant.Grav.13:3057-3068,1996 | 10.1088/0264-9381/13/11/019 | TIFR-TAP Preprint | gr-qc | null | Further to results in [9], pointing out the role of initial density and
velocity distributions towards determining the final outcome of spherical dust
collapse, the causal structure of singularity is examined here in terms of
evolution of the apparent horizon. We also bring out several related features
which throw some useful light towards understanding the nature of this
singularity, including the behaviour of geodesic families coming out and some
aspects related to the stability of singularity.
| [
{
"created": "Wed, 24 Apr 1996 09:21:39 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Aug 1996 13:38:38 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Jhingan",
"Sanjay",
""
],
[
"Joshi",
"P. S.",
""
],
[
"Singh",
"T. P.",
""
]
] | Further to results in [9], pointing out the role of initial density and velocity distributions towards determining the final outcome of spherical dust collapse, the causal structure of singularity is examined here in terms of evolution of the apparent horizon. We also bring out several related features which throw some useful light towards understanding the nature of this singularity, including the behaviour of geodesic families coming out and some aspects related to the stability of singularity. |
2307.14616 | Jiliang Jing | Changkai Chen and Jiliang Jing | Radiation fluxes of gravitational, electromagnetic, and scalar
perturbations in type-D black holes: an exact approach | 23 pages, 5 figures, and 6 tables | JCAP 11 (2023) 070 | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We present a novel method that solves Teukolsky equations with the source to
calculate radiation fluxes at infinity and event horizon for any perturbation
fields of type-D black holes. For the first time, we use the confluent Heun
function to obtain the exact solutions of ingoing and outgoing waves for the
Teukolsky equation. This benefits from our derivation of the asymptotic
analytic expression of the confluent Heun function at infinity. It is
interesting to note that these exact solutions are not subject to any
constraints, such as low-frequency and weak-field. To illustrate the
correctness, we apply these exact solutions to calculate the gravitational,
electromagnetic, and scalar radiations of the Schwarzschild black hole.
Numerical results show that the proposed exact solution appreciably improves
the computational accuracy and efficiency compared with the 23rd post-Newtonian
order expansion and the Mano-Suzuki-Takasugi method.
| [
{
"created": "Thu, 27 Jul 2023 04:06:10 GMT",
"version": "v1"
},
{
"created": "Fri, 8 Sep 2023 00:35:22 GMT",
"version": "v2"
}
] | 2024-03-13 | [
[
"Chen",
"Changkai",
""
],
[
"Jing",
"Jiliang",
""
]
] | We present a novel method that solves Teukolsky equations with the source to calculate radiation fluxes at infinity and event horizon for any perturbation fields of type-D black holes. For the first time, we use the confluent Heun function to obtain the exact solutions of ingoing and outgoing waves for the Teukolsky equation. This benefits from our derivation of the asymptotic analytic expression of the confluent Heun function at infinity. It is interesting to note that these exact solutions are not subject to any constraints, such as low-frequency and weak-field. To illustrate the correctness, we apply these exact solutions to calculate the gravitational, electromagnetic, and scalar radiations of the Schwarzschild black hole. Numerical results show that the proposed exact solution appreciably improves the computational accuracy and efficiency compared with the 23rd post-Newtonian order expansion and the Mano-Suzuki-Takasugi method. |
2302.02920 | Nicolas Lecoeur | Eugeny Babichev, Christos Charmousis, Mokhtar Hassaine, Nicolas
Lecoeur | Conformally coupled scalar in Lovelock theory | null | null | 10.1103/PhysRevD.107.084050 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In arbitrary higher dimension, we consider the combination of Lovelock
gravity alongside a scalar-tensor action built out of higher order operators
and Euler densities. The latter action is constructed in such a way as to
ensure conformal invariance for the scalar field. For the combined version of
these theories, we show the existence of black hole solutions interpreted as
stealth configurations within Lovelock gravity theory. The scalar field
solutions are endowed with an integration constant that may be identified as a
scalar charge. In particular, we show that these stealth solutions can be
extended to include a time-dependent scalar field despite the underlying theory
being non shift-symmetric. Finally, we present a procedure to obtain a
non-conformally invariant action in even dimensions from the considered theory.
For the target theory, the scalar field is not conformally coupled to gravity
although the scalar field equation itself is conformally invariant. By means of
this procedure, the black hole stealth configurations are converted into
non-stealth black hole solutions, as discovered recently in four dimensions.
| [
{
"created": "Mon, 6 Feb 2023 16:50:57 GMT",
"version": "v1"
}
] | 2023-05-10 | [
[
"Babichev",
"Eugeny",
""
],
[
"Charmousis",
"Christos",
""
],
[
"Hassaine",
"Mokhtar",
""
],
[
"Lecoeur",
"Nicolas",
""
]
] | In arbitrary higher dimension, we consider the combination of Lovelock gravity alongside a scalar-tensor action built out of higher order operators and Euler densities. The latter action is constructed in such a way as to ensure conformal invariance for the scalar field. For the combined version of these theories, we show the existence of black hole solutions interpreted as stealth configurations within Lovelock gravity theory. The scalar field solutions are endowed with an integration constant that may be identified as a scalar charge. In particular, we show that these stealth solutions can be extended to include a time-dependent scalar field despite the underlying theory being non shift-symmetric. Finally, we present a procedure to obtain a non-conformally invariant action in even dimensions from the considered theory. For the target theory, the scalar field is not conformally coupled to gravity although the scalar field equation itself is conformally invariant. By means of this procedure, the black hole stealth configurations are converted into non-stealth black hole solutions, as discovered recently in four dimensions. |
1111.3327 | Arif Mohd | Luca Bombelli, Arif Mohd | Asymptotically anti de Sitter spacetimes in three dimensions | To be published in the proceedings of the XII Marcel Grossmann
meeting held in Paris in July 2009 | null | 10.1142/9789814374552_0151 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit the asymptotically Anti de Sitter spacetimes in three dimensions.
Using the conformal-completion technique, we formulate the boundary conditions
in a covariant fashion and construct the global charges associated with the
asymptotic symmetries. The charges so constructed are conserved for the
asymptotic Killing vectors fields but are not conserved for the asymptotic
conformal Killing vector fields. The quantity integrated to obtain the global
charge is interpreted as the Brown-York boundary stress-energy tensor and it is
found not to be traceless. The trace is interpreted as the trace anomaly and it
turns out to be the same as the Brown-Henneaux central charge.
| [
{
"created": "Mon, 14 Nov 2011 19:09:49 GMT",
"version": "v1"
}
] | 2016-11-15 | [
[
"Bombelli",
"Luca",
""
],
[
"Mohd",
"Arif",
""
]
] | We revisit the asymptotically Anti de Sitter spacetimes in three dimensions. Using the conformal-completion technique, we formulate the boundary conditions in a covariant fashion and construct the global charges associated with the asymptotic symmetries. The charges so constructed are conserved for the asymptotic Killing vectors fields but are not conserved for the asymptotic conformal Killing vector fields. The quantity integrated to obtain the global charge is interpreted as the Brown-York boundary stress-energy tensor and it is found not to be traceless. The trace is interpreted as the trace anomaly and it turns out to be the same as the Brown-Henneaux central charge. |
gr-qc/9711009 | Hideki Asada | Hideki Asada and Toshifumi Futamase | Propagation of gravitational waves from slow motion sources in a Coulomb
type potential | 13 pages, no figures, to be published in Phys. Rev. D | Phys.Rev.D56:6062-6066,1997 | 10.1103/PhysRevD.56.R6062 | YITP-97-43 | gr-qc | null | We consider the propagation of gravitational waves generated by slow motion
sources in Coulomb type potential due to the mass of the source. Then, the
formula for gravitational waveform including tail is obtained in a
straightforward manner by using the spherical Coulomb function. We discuss its
relation with the formula in the previous work.
| [
{
"created": "Wed, 5 Nov 1997 02:27:50 GMT",
"version": "v1"
}
] | 2009-12-30 | [
[
"Asada",
"Hideki",
""
],
[
"Futamase",
"Toshifumi",
""
]
] | We consider the propagation of gravitational waves generated by slow motion sources in Coulomb type potential due to the mass of the source. Then, the formula for gravitational waveform including tail is obtained in a straightforward manner by using the spherical Coulomb function. We discuss its relation with the formula in the previous work. |
2103.07179 | Karim Mosani | Karim Mosani, Dipanjan Dey, and Pankaj S. Joshi | Globally visible singularity in an astrophysical setup | 12 pages, 4 figures, 1 table | Monthly Notices of Royal Astronomical Society Volume 504 Issue 4
July 2021 Pages 4743 to 4750 | 10.1093/mnras/stab1186 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The global visibility of a singularity as an end state of the gravitational
collapse of a spherically symmetric pressureless cloud is investigated. We show
the existence of a non-zero measured set of parameters: the total mass and the
initial mean density of the collapsing cloud, giving rise to a physically
strong globally visible singularity as the end state for a fixed velocity
function. The existence of such a set indicates that such singularity is stable
under small perturbation in the initial data causing its existence. This is
true for marginally as well as non-marginally bound cases. The possibility of
the presence of such suitable parameters in the astrophysical setup is then
studied: $1)$ The singularities' requirements at the center of the M87 galaxy
and at the center of our galaxy (SgrA*) to be globally visible are discussed in
terms of the initial size of the collapsing cloud forming them, presuming that
such singularities are formed due to gravitational collapse. $2)$ The
requirement for the primordial singularities formed due to a collapsing
configuration after getting detached from the background universe, at the time
of matter-dominated era just after the time of matter-radiation equality, to be
globally visible, is discussed. $3)$ The scenario of the collapse of a neutron
star after reaching a critical mass, which is achieved by accreting the
supernova ejecta expelled by its binary companion core progenitor, is
considered. The primary aim of this paper is to show that globally visible
singularities can form in astrophysical setups under appropriate circumstances.
| [
{
"created": "Fri, 12 Mar 2021 09:57:14 GMT",
"version": "v1"
}
] | 2022-11-15 | [
[
"Mosani",
"Karim",
""
],
[
"Dey",
"Dipanjan",
""
],
[
"Joshi",
"Pankaj S.",
""
]
] | The global visibility of a singularity as an end state of the gravitational collapse of a spherically symmetric pressureless cloud is investigated. We show the existence of a non-zero measured set of parameters: the total mass and the initial mean density of the collapsing cloud, giving rise to a physically strong globally visible singularity as the end state for a fixed velocity function. The existence of such a set indicates that such singularity is stable under small perturbation in the initial data causing its existence. This is true for marginally as well as non-marginally bound cases. The possibility of the presence of such suitable parameters in the astrophysical setup is then studied: $1)$ The singularities' requirements at the center of the M87 galaxy and at the center of our galaxy (SgrA*) to be globally visible are discussed in terms of the initial size of the collapsing cloud forming them, presuming that such singularities are formed due to gravitational collapse. $2)$ The requirement for the primordial singularities formed due to a collapsing configuration after getting detached from the background universe, at the time of matter-dominated era just after the time of matter-radiation equality, to be globally visible, is discussed. $3)$ The scenario of the collapse of a neutron star after reaching a critical mass, which is achieved by accreting the supernova ejecta expelled by its binary companion core progenitor, is considered. The primary aim of this paper is to show that globally visible singularities can form in astrophysical setups under appropriate circumstances. |
1703.03459 | Dieter Van den Bleeken | Dieter Van den Bleeken | Torsional Newton-Cartan gravity from the large $c$ expansion of General
Relativity | 25 pages, v3 footnote on Kerr corrected, ref added | null | 10.1088/1361-6382/aa83d4 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit the manifestly covariant large $c$ expansion of General
Relativity, $c$ being the speed of light. Assuming the relativistic connection
has no pole in $c^{-2}$, this expansion is known to reproduce Newton-Cartan
gravity and a covariant version of Post-Newtonian corrections to it. We show
that relaxing this assumption leads to the inclusion of twistless torsion in
the effective non-relativistic theory. We argue that the resulting TTNC theory
is an effective description of a non-relativistic regime of General Relativity
that extends Newtonian physics by including strong gravitational time dilation.
| [
{
"created": "Thu, 9 Mar 2017 20:56:04 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Sep 2017 10:15:59 GMT",
"version": "v2"
},
{
"created": "Wed, 27 Mar 2019 05:33:42 GMT",
"version": "v3"
}
] | 2019-03-28 | [
[
"Bleeken",
"Dieter Van den",
""
]
] | We revisit the manifestly covariant large $c$ expansion of General Relativity, $c$ being the speed of light. Assuming the relativistic connection has no pole in $c^{-2}$, this expansion is known to reproduce Newton-Cartan gravity and a covariant version of Post-Newtonian corrections to it. We show that relaxing this assumption leads to the inclusion of twistless torsion in the effective non-relativistic theory. We argue that the resulting TTNC theory is an effective description of a non-relativistic regime of General Relativity that extends Newtonian physics by including strong gravitational time dilation. |
gr-qc/0511149 | Franz Hinterleitner | Roman Steigl, Franz Hinterleitner | Factor ordering in standard quantum cosmology | 15 pages, 3 figures | Class.Quant.Grav. 23 (2006) 3879-3894 | 10.1088/0264-9381/23/11/013 | null | gr-qc | null | The Wheeler-DeWitt equation of Friedmann models with a massless quantum field
is formulated with arbitrary factor ordering of the Hamiltonian constraint
operator. A scalar product of wave functions is constructed, giving rise to a
probability interpretation and making comparison with the classical solution
possible. In general the bahaviour of the wave function of the model depends on
a critical energy of the matter field, which, in turn, depends on the chosen
factor ordering. By certain choices of the ordering the critical energy can be
pushed down to zero.
| [
{
"created": "Tue, 29 Nov 2005 16:45:05 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Steigl",
"Roman",
""
],
[
"Hinterleitner",
"Franz",
""
]
] | The Wheeler-DeWitt equation of Friedmann models with a massless quantum field is formulated with arbitrary factor ordering of the Hamiltonian constraint operator. A scalar product of wave functions is constructed, giving rise to a probability interpretation and making comparison with the classical solution possible. In general the bahaviour of the wave function of the model depends on a critical energy of the matter field, which, in turn, depends on the chosen factor ordering. By certain choices of the ordering the critical energy can be pushed down to zero. |
1509.04878 | Andrea Geralico | Donato Bini, Eduardo Bittencourt, Andrea Geralico | Massless Dirac particles in the vacuum C-metric | 18 pages, 2 figures; accepted for publication in Classical and
Quantum Gravity | null | 10.1088/0264-9381/32/21/215010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the behavior of massless Dirac particles in the vacuum C-metric
spacetime, representing the nonlinear superposition of the Schwarzschild black
hole solution and the Rindler flat spacetime associated with uniformly
accelerated observers. Under certain conditions, the C-metric can be considered
as a unique laboratory to test the coupling between intrinsic properties of
particles and fields with the background acceleration in the full (exact)
strong-field regime. The Dirac equation is separable by using, e.g., a
spherical-like coordinate system, reducing the problem to one-dimensional
radial and angular parts. Both radial and angular equations can be solved
exactly in terms of general Heun functions. We also provide perturbative
solutions to first-order in a suitably defined acceleration parameter, and
compute the acceleration-induced corrections to the particle absorption rate as
well as to the angle-averaged cross section of the associated scattering
problem in the low-frequency limit. Furthermore, we show that the angular
eigenvalue problem can be put in one-to-one correspondence with the analogous
problem for a Kerr spacetime, by identifying a map between these "acceleration"
harmonics and Kerr spheroidal harmonics. Finally, in this respect we discuss
the nature of the coupling between intrinsic spin and spacetime acceleration in
comparison with the well known Kerr spin-rotation coupling.
| [
{
"created": "Wed, 16 Sep 2015 10:46:26 GMT",
"version": "v1"
}
] | 2015-10-21 | [
[
"Bini",
"Donato",
""
],
[
"Bittencourt",
"Eduardo",
""
],
[
"Geralico",
"Andrea",
""
]
] | We study the behavior of massless Dirac particles in the vacuum C-metric spacetime, representing the nonlinear superposition of the Schwarzschild black hole solution and the Rindler flat spacetime associated with uniformly accelerated observers. Under certain conditions, the C-metric can be considered as a unique laboratory to test the coupling between intrinsic properties of particles and fields with the background acceleration in the full (exact) strong-field regime. The Dirac equation is separable by using, e.g., a spherical-like coordinate system, reducing the problem to one-dimensional radial and angular parts. Both radial and angular equations can be solved exactly in terms of general Heun functions. We also provide perturbative solutions to first-order in a suitably defined acceleration parameter, and compute the acceleration-induced corrections to the particle absorption rate as well as to the angle-averaged cross section of the associated scattering problem in the low-frequency limit. Furthermore, we show that the angular eigenvalue problem can be put in one-to-one correspondence with the analogous problem for a Kerr spacetime, by identifying a map between these "acceleration" harmonics and Kerr spheroidal harmonics. Finally, in this respect we discuss the nature of the coupling between intrinsic spin and spacetime acceleration in comparison with the well known Kerr spin-rotation coupling. |
2103.04865 | Masoud Ghezelbash | Masoud Ghezelbash, Haryanto M. Siahaan | Magnetized Kerr-Newman-Taub-NUT spacetimes | 38 pages, 17 figures, typos corrected, one appendix added | The European Physical Journal C 81, 621 (2021) | 10.1140/epjc/s10052-021-09430-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find a new class of exact solutions in the Einstein-Maxwell theory by
employing the Ernst magnetization process to the Kerr-Newman-Taub-NUT
spacetimes. We study the solutions and find that they are regular everywhere.
We also find the quasilocal conserved quantities for the spacetimes, the
corresponding Smarr formula and the first law of thermodynamics.
| [
{
"created": "Mon, 8 Mar 2021 16:15:27 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Apr 2021 17:21:36 GMT",
"version": "v2"
},
{
"created": "Mon, 5 Jul 2021 20:22:43 GMT",
"version": "v3"
}
] | 2021-08-10 | [
[
"Ghezelbash",
"Masoud",
""
],
[
"Siahaan",
"Haryanto M.",
""
]
] | We find a new class of exact solutions in the Einstein-Maxwell theory by employing the Ernst magnetization process to the Kerr-Newman-Taub-NUT spacetimes. We study the solutions and find that they are regular everywhere. We also find the quasilocal conserved quantities for the spacetimes, the corresponding Smarr formula and the first law of thermodynamics. |
2306.11491 | Kostas Kleidis | Kostas Kleidis | Semiclassical Quadratic Gravity Revisited | 7 pages, Updated version of the presentation at the International
Workshop on Cosmology & Gravitational Physics, December 15 - 16, 2005,
Thessaloniki, Greece, N. K. Spyrou, N. Stergioulas and C. Tsagas (eds.).
arXiv admin note: text overlap with arXiv:hep-th/0209093 | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The semiclassical interaction of the gravitational with a quantum scalar
field is considered, in view of the renormalizability of the associated
energy-momentum tensor in a n-dimensional curved spacetime resulting from a
quadratic gravitational lagrangian. It is shown that, in this case, a novel
coupling between the square curvature term, ${\cal R}^2$, and the quantum field
needs to be introduced. The interaction so considered, discards any
higher-order derivative terms from the associated gravitational field
equations, but, at the expense, it introduces a geometric source term in the
wave equation for the quantum field. Unlike the conformal coupling case, this
term does not represent an additional mass; hence, in quadratic gravity
theories, quantum fields can interact with gravity in a more generic way and
not only through their mass (or energy) content.
| [
{
"created": "Tue, 20 Jun 2023 12:23:08 GMT",
"version": "v1"
}
] | 2023-06-21 | [
[
"Kleidis",
"Kostas",
""
]
] | The semiclassical interaction of the gravitational with a quantum scalar field is considered, in view of the renormalizability of the associated energy-momentum tensor in a n-dimensional curved spacetime resulting from a quadratic gravitational lagrangian. It is shown that, in this case, a novel coupling between the square curvature term, ${\cal R}^2$, and the quantum field needs to be introduced. The interaction so considered, discards any higher-order derivative terms from the associated gravitational field equations, but, at the expense, it introduces a geometric source term in the wave equation for the quantum field. Unlike the conformal coupling case, this term does not represent an additional mass; hence, in quadratic gravity theories, quantum fields can interact with gravity in a more generic way and not only through their mass (or energy) content. |
1812.11425 | Yasser Elmahalawy Mr | Alexander Andrianov, Yasser Elmahalawy and Artem Starodubtsev | 2+1-dimensional gravity coupled to a dust shell: quantization in terms
of global phase space variables | 19 pages, 3 figures, conference | null | 10.1134/S0040577919090022 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform canonical analysis of a model in which gravity is coupled to a
spherically symmetric dust shell in 2+1 spacetime dimensions. The result is a
reduced action depending on a finite number of degrees of freedom. The emphasis
is made on finding canonical variables providing the global chart for the
entire phase space of the model. It turns out that all the distinct pieces of
momentum space could be assembled into a single manifold which has
ADS^{2}-geometry, and the global chart for it is provided by the Euler angles.
This results in both non-commutativity and discreteness in coordinate space,
which allows to resolve the central singularity. We also find the map between
ADS^{2} momentum space obtained here and momentum space in Kuchar variables,
which could be helpful in extending the present results to 3+1 dimensions.
| [
{
"created": "Sat, 29 Dec 2018 19:06:50 GMT",
"version": "v1"
}
] | 2019-10-23 | [
[
"Andrianov",
"Alexander",
""
],
[
"Elmahalawy",
"Yasser",
""
],
[
"Starodubtsev",
"Artem",
""
]
] | We perform canonical analysis of a model in which gravity is coupled to a spherically symmetric dust shell in 2+1 spacetime dimensions. The result is a reduced action depending on a finite number of degrees of freedom. The emphasis is made on finding canonical variables providing the global chart for the entire phase space of the model. It turns out that all the distinct pieces of momentum space could be assembled into a single manifold which has ADS^{2}-geometry, and the global chart for it is provided by the Euler angles. This results in both non-commutativity and discreteness in coordinate space, which allows to resolve the central singularity. We also find the map between ADS^{2} momentum space obtained here and momentum space in Kuchar variables, which could be helpful in extending the present results to 3+1 dimensions. |
2108.05861 | Marc Favata | Marc Favata, Chunglee Kim, K. G. Arun, JeongCho Kim, Hyung Won Lee | Constraining the orbital eccentricity of inspiralling compact binary
systems with Advanced LIGO | 31 pages, 11 figures, 4 tables; published in Phys. Rev. D. V2: minor
changes to match published version; some material moved to an appendix, minor
equation renumbering | Phys. Rev. D, 105, 023003 (2022) | 10.1103/PhysRevD.105.023003 | LIGO DCC P2100284 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The detection of ~50 coalescing compact binaries with the Advanced LIGO and
Virgo detectors has allowed us to test general relativity, constrain merger
rates, and look for evidence of tidal effects, compact object spins, higher
waveform modes, and black hole ringdowns. An effect that has not yet been
confidently detected is binary eccentricity, which might be present in a small
fraction of binaries formed dynamically. Here we discuss general limits on
eccentricity that can, in-principle, be placed on all types of compact object
binaries by a detector operating at the design sensitivity of Advanced LIGO.
Using a post-Newtonian model for gravitational-wave phasing valid in the small
eccentricity regime, we assess the relative measurement error for eccentricity
for a variety of spinning and non-spinning binaries. Errors and correlations
involving the mass and spin parameters are also investigated. We find that
decreasing the low frequency limit of a detector's observational frequency band
is one of the key design factors for increasing the odds of measuring binary
eccentricity. We also introduce and analytically explore the eccentric chirp
mass parameter, which replaces the chirp mass as the key measurable parameter
combination in eccentric gravitational waveform models. The eccentric chirp
mass parameter explains a degeneracy between the chirp mass and the
eccentricity. This degeneracy leads to a bias in the standard chirp mass
parameter. We also investigate the systematic parameter bias that arises when
eccentric systems are recovered using circular waveform templates. We use both
Fisher matrix and Bayesian-inference-based Markov Chain Monte Carlo (MCMC)
methods to investigate these parameter estimation issues, and we find good
agreement between the two approaches (for both statistical and systematic
errors) in the appropriate signal-to-noise ratio regime. (abridged)
| [
{
"created": "Thu, 12 Aug 2021 17:13:05 GMT",
"version": "v1"
},
{
"created": "Sat, 12 Mar 2022 04:36:45 GMT",
"version": "v2"
}
] | 2022-03-15 | [
[
"Favata",
"Marc",
""
],
[
"Kim",
"Chunglee",
""
],
[
"Arun",
"K. G.",
""
],
[
"Kim",
"JeongCho",
""
],
[
"Lee",
"Hyung Won",
""
]
] | The detection of ~50 coalescing compact binaries with the Advanced LIGO and Virgo detectors has allowed us to test general relativity, constrain merger rates, and look for evidence of tidal effects, compact object spins, higher waveform modes, and black hole ringdowns. An effect that has not yet been confidently detected is binary eccentricity, which might be present in a small fraction of binaries formed dynamically. Here we discuss general limits on eccentricity that can, in-principle, be placed on all types of compact object binaries by a detector operating at the design sensitivity of Advanced LIGO. Using a post-Newtonian model for gravitational-wave phasing valid in the small eccentricity regime, we assess the relative measurement error for eccentricity for a variety of spinning and non-spinning binaries. Errors and correlations involving the mass and spin parameters are also investigated. We find that decreasing the low frequency limit of a detector's observational frequency band is one of the key design factors for increasing the odds of measuring binary eccentricity. We also introduce and analytically explore the eccentric chirp mass parameter, which replaces the chirp mass as the key measurable parameter combination in eccentric gravitational waveform models. The eccentric chirp mass parameter explains a degeneracy between the chirp mass and the eccentricity. This degeneracy leads to a bias in the standard chirp mass parameter. We also investigate the systematic parameter bias that arises when eccentric systems are recovered using circular waveform templates. We use both Fisher matrix and Bayesian-inference-based Markov Chain Monte Carlo (MCMC) methods to investigate these parameter estimation issues, and we find good agreement between the two approaches (for both statistical and systematic errors) in the appropriate signal-to-noise ratio regime. (abridged) |
gr-qc/9902076 | Alfredo Macias | Friedrich W. Hehl, Alfredo Macias (UAM-Iztapalapa) | Metric-affine gauge theory of gravity II. Exact solutions | Revtex file, 25 pages, final version to appear in IJMPD | Int.J.Mod.Phys. D8 (1999) 399-416 | 10.1142/S0218271899000316 | UAM-I: 9902026 | gr-qc | null | In continuing our series on metric-affine gravity (see Gronwald IJMP D6
(1997) 263 for Part I), we review the exact solutions in this theory.
| [
{
"created": "Tue, 23 Feb 1999 18:13:45 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Apr 1999 17:31:01 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Hehl",
"Friedrich W.",
"",
"UAM-Iztapalapa"
],
[
"Macias",
"Alfredo",
"",
"UAM-Iztapalapa"
]
] | In continuing our series on metric-affine gravity (see Gronwald IJMP D6 (1997) 263 for Part I), we review the exact solutions in this theory. |
2108.07607 | Edward Wilson-Ewing | Edward Wilson-Ewing | Potential consequences of wormhole-mediated entanglement | 8 pages. v2: References added | Found. Phys. 51, 87 (2021) | 10.1007/s10701-021-00489-y | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | There are hints that the connectivity of space-time in quantum gravity could
emerge from entanglement, and it has further been proposed that any two
entangled particles may be connected by a quantum wormhole. One way to test
this proposal is by probing the electric field of an entangled charged particle
to determine whether its electric field leaks through the putative wormhole. In
addition, if such a wormhole is traversable, then it could be possible for the
collapse of the wave function to occur in a causal manner, with information
about the collapse travelling through the wormhole at the speed of light,
rather than the wave function collapse being a global and instantaneous event.
| [
{
"created": "Tue, 17 Aug 2021 13:10:50 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Aug 2021 16:17:26 GMT",
"version": "v2"
}
] | 2021-08-27 | [
[
"Wilson-Ewing",
"Edward",
""
]
] | There are hints that the connectivity of space-time in quantum gravity could emerge from entanglement, and it has further been proposed that any two entangled particles may be connected by a quantum wormhole. One way to test this proposal is by probing the electric field of an entangled charged particle to determine whether its electric field leaks through the putative wormhole. In addition, if such a wormhole is traversable, then it could be possible for the collapse of the wave function to occur in a causal manner, with information about the collapse travelling through the wormhole at the speed of light, rather than the wave function collapse being a global and instantaneous event. |
1710.10463 | Ayan Banerjee | S. K. Maurya, Ayan Banerjee, Sudan Hansraj | Role of pressure anisotropy on relativistic compact stars | 11 pages, 4 figures; v2:, texts are improved and updated to match
journal version | Phys. Rev. D 97, 044022 (2018) | 10.1103/PhysRevD.97.044022 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate a compact spherically symmetric relativistic body with
anisotropic particle pressure profiles. The distribution possesses
characteristics relevant to modeling compact stars within the framework of
general relativity. For this purpose, we consider a spatial metric potential of
Korkina and Orlyanskii [Ukr. Phys. J. 36, 885 (1991)] type in order to solve
the Einstein field equations. An additional prescription we make is that the
pressure anisotropy parameter takes the functional form proposed by Lake [Phys.
Rev. D 67, 104015 (2003)]. Specifying these two geometric quantities allows for
further analysis to be carried out in determining unknown constants and
obtaining a limit of the mass-radius diagram, which adequately describes
compact strange star candidates like Her X-1 and SMC X-1. Using the anisotropic
Tolman-Oppenheimer-Volkoff equations, we explore the hydrostatic equilibrium
and the stability of such compact objects. Then, we investigate other physical
features of this models, such as the energy conditions, speeds of sound and
compactness of the star in detail and show that our results satisfy all the
required elementary conditions for a physically acceptable stellar model. The
results obtained are useful in analyzing the stability of other anisotropic
compact objects like white dwarfs, neutron stars, and gravastars.
| [
{
"created": "Sat, 28 Oct 2017 13:27:44 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Feb 2018 20:56:11 GMT",
"version": "v2"
}
] | 2018-02-28 | [
[
"Maurya",
"S. K.",
""
],
[
"Banerjee",
"Ayan",
""
],
[
"Hansraj",
"Sudan",
""
]
] | We investigate a compact spherically symmetric relativistic body with anisotropic particle pressure profiles. The distribution possesses characteristics relevant to modeling compact stars within the framework of general relativity. For this purpose, we consider a spatial metric potential of Korkina and Orlyanskii [Ukr. Phys. J. 36, 885 (1991)] type in order to solve the Einstein field equations. An additional prescription we make is that the pressure anisotropy parameter takes the functional form proposed by Lake [Phys. Rev. D 67, 104015 (2003)]. Specifying these two geometric quantities allows for further analysis to be carried out in determining unknown constants and obtaining a limit of the mass-radius diagram, which adequately describes compact strange star candidates like Her X-1 and SMC X-1. Using the anisotropic Tolman-Oppenheimer-Volkoff equations, we explore the hydrostatic equilibrium and the stability of such compact objects. Then, we investigate other physical features of this models, such as the energy conditions, speeds of sound and compactness of the star in detail and show that our results satisfy all the required elementary conditions for a physically acceptable stellar model. The results obtained are useful in analyzing the stability of other anisotropic compact objects like white dwarfs, neutron stars, and gravastars. |
1812.05704 | Kirill Bronnikov | K.A. Bronnikov, K.A. Baleevskikh | On gravitational lensing by symmetric and asymmetric wormholes | 6 pages, 5 figures | Grav. Cosmol. 25, 44-49 (2019) | 10.1134/S020228931901002X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the peculiarities of gravitational lensing by spherically
symmetric wormholes if they are not symmetric with respect to their throats. It
is noticed, in particular, that wormholes always contain the so-called photon
spheres, near which the photon deflection angles can be arbitrarily large, but,
in general, the throat is such a sphere only for symmetric wormholes. In some
cases, photons from outside can cross the throat and return back from a
neighborhood of a photon sphere if the latter is located beyond the throat. Two
families of generally asymmetric wormhole configurations are considered as
examples: (1) anti-Fisher wormholes with a massless phantom scalar field as a
source of gravity, and (2) wormholes with a zero Ricci scalar that may be
interpreted as vacuum configurations in a brane world. For these metrics, the
photon effective potentials and deflection angles are found and discussed.
| [
{
"created": "Thu, 13 Dec 2018 21:44:14 GMT",
"version": "v1"
}
] | 2020-10-20 | [
[
"Bronnikov",
"K. A.",
""
],
[
"Baleevskikh",
"K. A.",
""
]
] | We discuss the peculiarities of gravitational lensing by spherically symmetric wormholes if they are not symmetric with respect to their throats. It is noticed, in particular, that wormholes always contain the so-called photon spheres, near which the photon deflection angles can be arbitrarily large, but, in general, the throat is such a sphere only for symmetric wormholes. In some cases, photons from outside can cross the throat and return back from a neighborhood of a photon sphere if the latter is located beyond the throat. Two families of generally asymmetric wormhole configurations are considered as examples: (1) anti-Fisher wormholes with a massless phantom scalar field as a source of gravity, and (2) wormholes with a zero Ricci scalar that may be interpreted as vacuum configurations in a brane world. For these metrics, the photon effective potentials and deflection angles are found and discussed. |
1711.03824 | A. Emrah Y\"ukselci | A. Sava\c{s} Arapo\u{g}lu, A. Emrah Y\"ukselci | Dynamical System Analysis of Quintessence Models with Exponential
Potential -- Revisited | 15 pages, 3 figures; matches the published version | Modern Physics Letters A, Vol. 34, No. 09, 1950069 (2019) | 10.1142/S021773231950069X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Dynamical system analysis of a universe model which contains matter,
radiation, and quintessence with exponential potential, $V \!(\phi)=V_{\!o} \,
exp(-\alpha \kappa \phi) \,$, is studied in the light of recent observations
and the tensions between different datasets. The three-dimensional phase space
is constructed by the energy density parameters and all the critical points of
the model with their physical meanings are investigated. This approach provides
an easy way of comparing the model directly with the observations. We consider
a solution that is compatible with observations and is continuous in the phase
space in both directions of time, past and future. Although in many studies of
late-time acceleration the radiation is neglected, here we consider all
components together and this makes the calculated effective equation of state
parameter more realistic. Additionally, a relation between potential parameter,
$\alpha$, and the value of quintessence equation of state parameter,
$\omega_\phi(t_o)$, today is found by using numerical analysis. We conclude
that $\alpha$ has to be small in order to explain the current accelerated phase
of the universe and this result can be seen directly from the relation we
obtain. Finally, we compare the usual dynamical system approach with the
approach that we follow in this paper.
| [
{
"created": "Fri, 10 Nov 2017 14:04:25 GMT",
"version": "v1"
},
{
"created": "Sat, 15 Feb 2020 13:44:02 GMT",
"version": "v2"
}
] | 2020-02-18 | [
[
"Arapoğlu",
"A. Savaş",
""
],
[
"Yükselci",
"A. Emrah",
""
]
] | Dynamical system analysis of a universe model which contains matter, radiation, and quintessence with exponential potential, $V \!(\phi)=V_{\!o} \, exp(-\alpha \kappa \phi) \,$, is studied in the light of recent observations and the tensions between different datasets. The three-dimensional phase space is constructed by the energy density parameters and all the critical points of the model with their physical meanings are investigated. This approach provides an easy way of comparing the model directly with the observations. We consider a solution that is compatible with observations and is continuous in the phase space in both directions of time, past and future. Although in many studies of late-time acceleration the radiation is neglected, here we consider all components together and this makes the calculated effective equation of state parameter more realistic. Additionally, a relation between potential parameter, $\alpha$, and the value of quintessence equation of state parameter, $\omega_\phi(t_o)$, today is found by using numerical analysis. We conclude that $\alpha$ has to be small in order to explain the current accelerated phase of the universe and this result can be seen directly from the relation we obtain. Finally, we compare the usual dynamical system approach with the approach that we follow in this paper. |
gr-qc/0208075 | Valerio Bozza | V. Bozza | Gravitational lensing in the strong field limit | 10 pages, 5 figures, in press on Physical Review D | Phys.Rev. D66 (2002) 103001 | 10.1103/PhysRevD.66.103001 | null | gr-qc astro-ph | null | We provide an analytic method to discriminate among different types of black
holes on the ground of their strong field gravitational lensing properties. We
expand the deflection angle of the photon in the neighbourhood of complete
capture, defining a strong field limit, in opposition to the standard weak
field limit. This expansion is worked out for a completely generic spherically
symmetric spacetime, without any reference to the field equations and just
assuming that the light ray follows the geodesics equation. We prove that the
deflection angle always diverges logarithmically when the minimum impact
parameter is reached. We apply this general formalism to Schwarzschild,
Reissner-Nordstrom and Janis-Newman-Winicour black holes. We then compare the
coefficients characterizing these metrics and find that different collapsed
objects are characterized by different strong field limits. The strong field
limit coefficients are directly connected to the observables, such as the
position and the magnification of the relativistic images. As a concrete
example, we consider the black hole at the centre of our galaxy and estimate
the optical resolution needed to investigate its strong field behaviour through
its relativistic images.
| [
{
"created": "Mon, 26 Aug 2002 11:41:11 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Sep 2002 11:49:05 GMT",
"version": "v2"
},
{
"created": "Mon, 21 Oct 2002 09:14:57 GMT",
"version": "v3"
}
] | 2009-11-07 | [
[
"Bozza",
"V.",
""
]
] | We provide an analytic method to discriminate among different types of black holes on the ground of their strong field gravitational lensing properties. We expand the deflection angle of the photon in the neighbourhood of complete capture, defining a strong field limit, in opposition to the standard weak field limit. This expansion is worked out for a completely generic spherically symmetric spacetime, without any reference to the field equations and just assuming that the light ray follows the geodesics equation. We prove that the deflection angle always diverges logarithmically when the minimum impact parameter is reached. We apply this general formalism to Schwarzschild, Reissner-Nordstrom and Janis-Newman-Winicour black holes. We then compare the coefficients characterizing these metrics and find that different collapsed objects are characterized by different strong field limits. The strong field limit coefficients are directly connected to the observables, such as the position and the magnification of the relativistic images. As a concrete example, we consider the black hole at the centre of our galaxy and estimate the optical resolution needed to investigate its strong field behaviour through its relativistic images. |
1611.03153 | Chikun Ding | Chikun Ding and Changqing Liu | Dispersion relation and surface gravity of universal horizons | 12 pages, accepted for publication in Sci China-Phys Mech Astron | Sci China-PMA 60 050411 (2017) | 10.1007/s11433-017-9012-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In Einstein-aether theory, violating Lorentz invariance permits some
super-luminal communications, and the universal horizon can trap excitations
traveling at arbitrarily high velocities. To better understand the nature of
these universal horizons, we first modify the ray tracing method, and then use
it to study their surface gravity in charged Einstein-aether black hole
spacetime. Instead of the previous result in Ref. [Phys. Rev. D 89, 064061],
our results show that the surface gravity of the universal horizon is dependent
on the specific dispersion relation, $\kappa_{UH}=2(z-1)\kappa_{uh}/z$, where
$z$ denotes the power of the leading term in the superluminal dispersion
relation, characterizing different species of particles. And the associated
Hawking temperatures also are different with $z$. These findings, which
coincide with those in Ref. [Nucl. Phys. B 913, 694] derived by the tunneling
method, provide some full understanding of black hole thermodynamics in
Lorentz-violating theories.
| [
{
"created": "Thu, 10 Nov 2016 01:34:01 GMT",
"version": "v1"
},
{
"created": "Fri, 24 Feb 2017 02:46:02 GMT",
"version": "v2"
}
] | 2017-03-28 | [
[
"Ding",
"Chikun",
""
],
[
"Liu",
"Changqing",
""
]
] | In Einstein-aether theory, violating Lorentz invariance permits some super-luminal communications, and the universal horizon can trap excitations traveling at arbitrarily high velocities. To better understand the nature of these universal horizons, we first modify the ray tracing method, and then use it to study their surface gravity in charged Einstein-aether black hole spacetime. Instead of the previous result in Ref. [Phys. Rev. D 89, 064061], our results show that the surface gravity of the universal horizon is dependent on the specific dispersion relation, $\kappa_{UH}=2(z-1)\kappa_{uh}/z$, where $z$ denotes the power of the leading term in the superluminal dispersion relation, characterizing different species of particles. And the associated Hawking temperatures also are different with $z$. These findings, which coincide with those in Ref. [Nucl. Phys. B 913, 694] derived by the tunneling method, provide some full understanding of black hole thermodynamics in Lorentz-violating theories. |
2207.10933 | Song Li | Song Li, Temurbek Mirzaev, Ahmadjon A. Abdujabbarov, Daniele
Malafarina, Bobomurat Ahmedov and Wen-Biao Han | Constraining the deformation of a black hole mimicker from the shadow | 15 pages, 7 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a black hole mimicker given by an exact solution of the
stationary and axially symmetric field equations in vacuum known as the
$\delta$-Kerr metric. We study its optical properties based on a ray-tracing
code for photon motion and characterize the apparent shape of the shadow of the
compact object and compare it with the Kerr black hole. For the purpose of
obtaining qualitative estimates related to the observed shadow of the
supermassive compact object in the galaxy M87 we focus on values of the
object's spin $a$ and inclination angle of observation $\theta_0$ close to the
measured values. We then apply the model to the shadow of the $\delta$-Kerr
metric to obtain onstraints on the allowed values of the deformation parameter.
We show that based uniquely on one set of observations of the shadow's boundary
it is not possible to exclude the $\delta$-Kerr solution as a viable source for
the geometry in the exterior of the compact object.
| [
{
"created": "Fri, 22 Jul 2022 08:15:10 GMT",
"version": "v1"
}
] | 2022-07-25 | [
[
"Li",
"Song",
""
],
[
"Mirzaev",
"Temurbek",
""
],
[
"Abdujabbarov",
"Ahmadjon A.",
""
],
[
"Malafarina",
"Daniele",
""
],
[
"Ahmedov",
"Bobomurat",
""
],
[
"Han",
"Wen-Biao",
""
]
] | We consider a black hole mimicker given by an exact solution of the stationary and axially symmetric field equations in vacuum known as the $\delta$-Kerr metric. We study its optical properties based on a ray-tracing code for photon motion and characterize the apparent shape of the shadow of the compact object and compare it with the Kerr black hole. For the purpose of obtaining qualitative estimates related to the observed shadow of the supermassive compact object in the galaxy M87 we focus on values of the object's spin $a$ and inclination angle of observation $\theta_0$ close to the measured values. We then apply the model to the shadow of the $\delta$-Kerr metric to obtain onstraints on the allowed values of the deformation parameter. We show that based uniquely on one set of observations of the shadow's boundary it is not possible to exclude the $\delta$-Kerr solution as a viable source for the geometry in the exterior of the compact object. |
2301.02793 | Sung-Won Kim | Sung-Won Kim | Gravitational Waves by Perturbation of a Slowly Rotating Thin-Shell
Wormhole | 5 pages, 3 figures | Journal of the Korean Physical Society (2023) | 10.1007/s40042-022-00699-1 | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | In this paper, the gravitational wave generation by a slowly rotating
thin-shell wormhole is considered. Since the rotating thin-shell wormhole is
assumed to be an axisymmetric rigid body, the rotation axis coincides with the
largest principal axis which means there is no precession motion. However, if
there is a perturbation in the angular velocity, the rotating wormhole can move
with precession by perturbation which make arise the gravitational waves. We
derive the gravitational wave spectrum, energy loss rate, and angular momentum
loss rate.
| [
{
"created": "Sat, 7 Jan 2023 07:08:26 GMT",
"version": "v1"
}
] | 2023-01-10 | [
[
"Kim",
"Sung-Won",
""
]
] | In this paper, the gravitational wave generation by a slowly rotating thin-shell wormhole is considered. Since the rotating thin-shell wormhole is assumed to be an axisymmetric rigid body, the rotation axis coincides with the largest principal axis which means there is no precession motion. However, if there is a perturbation in the angular velocity, the rotating wormhole can move with precession by perturbation which make arise the gravitational waves. We derive the gravitational wave spectrum, energy loss rate, and angular momentum loss rate. |
2005.13260 | Che-Yu Chen | Mariam Bouhmadi-L\'opez, Che-Yu Chen, Xiao Yan Chew, Yen Chin Ong,
Dong-han Yeom | Regular Black Hole Interior Spacetime Supported by Three-Form Field | 13 pages, 6 figures. Updated to match the published version | Eur. Phys. J. C (2021) 81:278 | 10.1140/epjc/s10052-021-09080-1 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we show that a minimally coupled 3-form endowed with a proper
potential can support a regular black hole interior. By choosing an appropriate
form for the metric function representing the radius of the 2-sphere, we solve
for the 3-form field and its potential. Using the obtained solution, we
construct an interior black hole spacetime which is everywhere regular. The
singularity is replaced with a Nariai-type spacetime, whose topology is
$\text{dS}_2 \times \text{S}^2$, in which the radius of the 2-sphere is
constant. So long as the interior continues to expand indefinitely, the
geometry becomes essentially compactified. The 2-dimensional de Sitter geometry
appears despite the negative potential of the 3-form field. Such a dynamical
compactification could shed some light on the origin of de Sitter geometry of
our Universe, exacerbated by the Swampland conjecture. In addition, we show
that the spacetime is geodesically complete. The geometry is singularity-free
due to the violation of the null energy condition.
| [
{
"created": "Wed, 27 May 2020 09:54:57 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Apr 2021 13:36:54 GMT",
"version": "v2"
}
] | 2021-04-06 | [
[
"Bouhmadi-López",
"Mariam",
""
],
[
"Chen",
"Che-Yu",
""
],
[
"Chew",
"Xiao Yan",
""
],
[
"Ong",
"Yen Chin",
""
],
[
"Yeom",
"Dong-han",
""
]
] | In this paper, we show that a minimally coupled 3-form endowed with a proper potential can support a regular black hole interior. By choosing an appropriate form for the metric function representing the radius of the 2-sphere, we solve for the 3-form field and its potential. Using the obtained solution, we construct an interior black hole spacetime which is everywhere regular. The singularity is replaced with a Nariai-type spacetime, whose topology is $\text{dS}_2 \times \text{S}^2$, in which the radius of the 2-sphere is constant. So long as the interior continues to expand indefinitely, the geometry becomes essentially compactified. The 2-dimensional de Sitter geometry appears despite the negative potential of the 3-form field. Such a dynamical compactification could shed some light on the origin of de Sitter geometry of our Universe, exacerbated by the Swampland conjecture. In addition, we show that the spacetime is geodesically complete. The geometry is singularity-free due to the violation of the null energy condition. |
1601.03946 | Mohsen Dehghani | Mohsen Dehghani | Group theoretical interpretation of the modified gravity in de Sitter
space | 20 pages | J. High Energy Phys. 03(2016)203 | 10.1007/JHEP03(2016)203 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A frame work has been presented for theoretical interpretation of various
modified gravitational models which is based on the group theoretical approach
and unitary irreducible representations (UIR's) of de Sitter (dS) group. In
order to illustrate the application of the proposed method, a model of modified
gravity has been investigated. The background field method has been utilized
and the linearized modified gravitational field equation has been obtained in
the 4-dimensional dS space-time as the background. The field equation has been
written as the eigne-value equation of the Casimir operators of dS space using
the flat 5-dimensional ambient space notations. The Minkowskian correspondence
of the theory has been obtained by taking the zero curvature limit. It has been
shown that under some simple conditions, the linearized modified field equation
transforms according to two of the UIR's of dS group labeled by $\Pi^\pm_{2,1}$
and $\Pi^\pm_{2,2}$ in the discrete series. It means that the proposed modified
gravitational theory can be a suitable one to describe the quantum
gravitational effects in its linear approximation on dS space. The field
equation has been solved and the solution has been written as the
multiplication of a symmetric rank-2 polarization tensor and a massless scalar
field using the ambient space notations. Also the two-point function has been
calculated in the ambient space formalism. It is dS invariant and free of any
theoretical problem.
| [
{
"created": "Thu, 14 Jan 2016 16:18:12 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Mar 2016 06:35:03 GMT",
"version": "v2"
}
] | 2016-05-30 | [
[
"Dehghani",
"Mohsen",
""
]
] | A frame work has been presented for theoretical interpretation of various modified gravitational models which is based on the group theoretical approach and unitary irreducible representations (UIR's) of de Sitter (dS) group. In order to illustrate the application of the proposed method, a model of modified gravity has been investigated. The background field method has been utilized and the linearized modified gravitational field equation has been obtained in the 4-dimensional dS space-time as the background. The field equation has been written as the eigne-value equation of the Casimir operators of dS space using the flat 5-dimensional ambient space notations. The Minkowskian correspondence of the theory has been obtained by taking the zero curvature limit. It has been shown that under some simple conditions, the linearized modified field equation transforms according to two of the UIR's of dS group labeled by $\Pi^\pm_{2,1}$ and $\Pi^\pm_{2,2}$ in the discrete series. It means that the proposed modified gravitational theory can be a suitable one to describe the quantum gravitational effects in its linear approximation on dS space. The field equation has been solved and the solution has been written as the multiplication of a symmetric rank-2 polarization tensor and a massless scalar field using the ambient space notations. Also the two-point function has been calculated in the ambient space formalism. It is dS invariant and free of any theoretical problem. |
gr-qc/9711035 | Richard Easther | Richard Easther and Kei-ichi Maeda | Chaotic Dynamics and Two-Field Inflation | Latex2e, psfrag (3.03) and Level 2 postscript [Comments about
reheating expanded (v2), glitches in references fixed (v3)] | Class.Quant.Grav. 16 (1999) 1637-1652 | 10.1088/0264-9381/16/5/313 | BROWN-HET-1099, WU-AP/67/97 | gr-qc astro-ph hep-ph | null | We demonstrate the existence of chaos in realistic models of two-field
inflation. The chaotic motion takes place after the end of inflation, when the
fields are free to oscillate and their motion is only lightly damped by the
expansion of the universe. We then investigate whether the presence of chaos
affects the predictions of two-field models, and show that chaos enhances the
production of topological defects and renders the growth rate of the universe
sensitively dependent upon the ``initial'' conditions at the beginning of the
oscillatory era.
| [
{
"created": "Tue, 11 Nov 1997 02:13:18 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Nov 1997 19:10:19 GMT",
"version": "v2"
},
{
"created": "Thu, 18 Dec 1997 23:43:48 GMT",
"version": "v3"
}
] | 2009-10-30 | [
[
"Easther",
"Richard",
""
],
[
"Maeda",
"Kei-ichi",
""
]
] | We demonstrate the existence of chaos in realistic models of two-field inflation. The chaotic motion takes place after the end of inflation, when the fields are free to oscillate and their motion is only lightly damped by the expansion of the universe. We then investigate whether the presence of chaos affects the predictions of two-field models, and show that chaos enhances the production of topological defects and renders the growth rate of the universe sensitively dependent upon the ``initial'' conditions at the beginning of the oscillatory era. |
1810.04743 | Thomas M\"adler | Thomas M\"adler | Affine-null metric formulation of General Relativity at two intersecting
null hypersurfaces | 28 pages, matches (up to reference listing) published version | Phys. Rev. D 99, 104048 (2019) | 10.1103/PhysRevD.99.104048 | null | gr-qc astro-ph.HE astro-ph.SR hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit Winicour's affine-null metric initial value formulation of General
Relativity, where the characteristic initial value formulation is set up with a
null metric having two affine parameters. In comparison to past work, where the
application of the formulation was aimed for the timelike-null initial value
problem, we consider here a boundary surface that is a null hypersurface. All
of the initial data are either metric functions or first derivatives of the
metric. Given such a set of initial data, Einstein equations can be integrated
in a hierarchical manner, where first a set of equations is solved
hierarchically on the null hypersurface serving as a boundary. Second, with the
obtained boundary values, a set of differential equations, similar to the
equations of the Bondi-Sachs formalism, comprising of hypersurface and
evolution equations is solved hierarchically to find the entire space-time
metric. An example is shown how the double null Israel black hole solution
arises after specification to spherical symmetry and vacuum. This black hole
solution is then discussed to with respect to Penrose conformal
compactification of spacetime.
| [
{
"created": "Wed, 10 Oct 2018 20:41:09 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Apr 2019 21:06:05 GMT",
"version": "v2"
},
{
"created": "Wed, 22 May 2019 18:29:38 GMT",
"version": "v3"
}
] | 2019-05-24 | [
[
"Mädler",
"Thomas",
""
]
] | We revisit Winicour's affine-null metric initial value formulation of General Relativity, where the characteristic initial value formulation is set up with a null metric having two affine parameters. In comparison to past work, where the application of the formulation was aimed for the timelike-null initial value problem, we consider here a boundary surface that is a null hypersurface. All of the initial data are either metric functions or first derivatives of the metric. Given such a set of initial data, Einstein equations can be integrated in a hierarchical manner, where first a set of equations is solved hierarchically on the null hypersurface serving as a boundary. Second, with the obtained boundary values, a set of differential equations, similar to the equations of the Bondi-Sachs formalism, comprising of hypersurface and evolution equations is solved hierarchically to find the entire space-time metric. An example is shown how the double null Israel black hole solution arises after specification to spherical symmetry and vacuum. This black hole solution is then discussed to with respect to Penrose conformal compactification of spacetime. |
gr-qc/9903073 | R. Michael Jones | R. Michael Jones (CIRES, University of Colorado, Boulder, Colorado,
U.S.A.) | The classical action for a Bianchi VI_h model | Latex, 31 pages | null | null | null | gr-qc | null | An estimate for the classical action for a Bianchi VI_h homogeneous spatially
closed cosmology is presented as a function of b, a parameter of the model that
is proportional to the relative rotation of the average inertial frame and the
bulk of matter in the universe. It is assumed (through the equation of state)
that a relativistic early universe is followed by a matter-dominated late
universe. The action is used in a saddlepoint approximation to a semiclassical
estimate for the wave function in quantum cosmology to explain why our inertial
frame seems not to rotate relative to the stars. The saddlepoint is at b=0, as
would be expected. Application of the saddlepoint approximation leads to the
result that only those classical geometries whose action differs from the
saddlepoint value for the action by an amount less than Planck's constant
contribute significantly to the integration to give the present value of the
wave function. Using estimates for our universe implies that only those
classical geometries for which the present relative rotation rate of inertial
frames and matter are less than about 10^(-130) radians per year contribute
significantly to the integration. This is well below the limit set by
experiment. The result depends on the ratio of the Hubble distance to the
Planck length, but does not depend on the details of the theory of quantum
gravity.
| [
{
"created": "Thu, 18 Mar 1999 22:37:50 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Jones",
"R. Michael",
"",
"CIRES, University of Colorado, Boulder, Colorado,\n U.S.A."
]
] | An estimate for the classical action for a Bianchi VI_h homogeneous spatially closed cosmology is presented as a function of b, a parameter of the model that is proportional to the relative rotation of the average inertial frame and the bulk of matter in the universe. It is assumed (through the equation of state) that a relativistic early universe is followed by a matter-dominated late universe. The action is used in a saddlepoint approximation to a semiclassical estimate for the wave function in quantum cosmology to explain why our inertial frame seems not to rotate relative to the stars. The saddlepoint is at b=0, as would be expected. Application of the saddlepoint approximation leads to the result that only those classical geometries whose action differs from the saddlepoint value for the action by an amount less than Planck's constant contribute significantly to the integration to give the present value of the wave function. Using estimates for our universe implies that only those classical geometries for which the present relative rotation rate of inertial frames and matter are less than about 10^(-130) radians per year contribute significantly to the integration. This is well below the limit set by experiment. The result depends on the ratio of the Hubble distance to the Planck length, but does not depend on the details of the theory of quantum gravity. |
gr-qc/9504032 | Thierry F. Kauffmann | Mark P. Haugan and Thierry F. Kauffmann | A New Test of the Einstein Equivalence Principle and the Isotropy of
Space | 21 pages, Latex, 3 Postscript figures | Phys.Rev.D52:3168-3175,1995 | 10.1103/PhysRevD.52.3168 | null | gr-qc | null | Recent research has established that nonsymmetric gravitation theories like
Moffat's NGT predict that a gravitational field singles out an orthogonal pair
of polarization states of light that propagate with different phase velocities.
We show that a much wider class of nonmetric theories encompassed by the $\chi
g$ formalism predict such violations of the Einstein equivalence principle.
This gravity-induced birefringence of space implies that propagation through a
gravitational field can alter the polarization of light. We use data from
polarization measurements of extragalactic sources to constrain birefringence
induced by the field of the Galaxy. Our new constraint is $10^8$ times sharper
than previous ones.
| [
{
"created": "Thu, 20 Apr 1995 21:28:35 GMT",
"version": "v1"
}
] | 2010-11-30 | [
[
"Haugan",
"Mark P.",
""
],
[
"Kauffmann",
"Thierry F.",
""
]
] | Recent research has established that nonsymmetric gravitation theories like Moffat's NGT predict that a gravitational field singles out an orthogonal pair of polarization states of light that propagate with different phase velocities. We show that a much wider class of nonmetric theories encompassed by the $\chi g$ formalism predict such violations of the Einstein equivalence principle. This gravity-induced birefringence of space implies that propagation through a gravitational field can alter the polarization of light. We use data from polarization measurements of extragalactic sources to constrain birefringence induced by the field of the Galaxy. Our new constraint is $10^8$ times sharper than previous ones. |
gr-qc/0610112 | Tao Mei | T. Mei | On isotropic metric of Schwarzschild solution of Einstein equation | 8 pages, no figure | null | null | null | gr-qc | null | The known static isotropic metric of Schwarzschild solution of Einstein
equation cannot cover with the range of r<2MG, a new isotropic metric of
Schwarzschild solution is obtained. The new isotropic metric has the
characters: (1) It is dynamic and periodic. (2) It has infinite singularities
of the spacetime. (3) It cannot cover with the range of 0<r<r0; On the other
hand, r0 can be small discretionarily. (4) It seemed as if the range of
negative r could be unavoidable, although this range is meaningless for the
Schwarzschild metric.
| [
{
"created": "Tue, 24 Oct 2006 07:53:03 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Mei",
"T.",
""
]
] | The known static isotropic metric of Schwarzschild solution of Einstein equation cannot cover with the range of r<2MG, a new isotropic metric of Schwarzschild solution is obtained. The new isotropic metric has the characters: (1) It is dynamic and periodic. (2) It has infinite singularities of the spacetime. (3) It cannot cover with the range of 0<r<r0; On the other hand, r0 can be small discretionarily. (4) It seemed as if the range of negative r could be unavoidable, although this range is meaningless for the Schwarzschild metric. |
gr-qc/0205028 | Jose Francisco da Rocha Neto | J. F. da Rocha-Neto and K. H. Castello-Branco | Gravitational Energy of Kerr and Kerr Anti-de Sitter Space-times in the
Teleparallel Geometry | 11 pages, 1 figure, to appear in JHEP11(2003)002 | JHEP0311:002,2003 | 10.1088/1126-6708/2003/11/002 | null | gr-qc hep-th | null | In the context of the Hamiltonian formulation of the teleparallel equivalent
of general relativity we compute the gravitational energy of Kerr and Kerr
Anti-de Sitter (Kerr-AdS) space-times. The present calculation is carried out
by means of an expression for the energy of the gravitational field that
naturally arises from the integral form of the constraint equations of the
formalism. In each case, the energy is exactly computed for finite and
arbitrary spacelike two-spheres, without any restriction on the metric
parameters. In particular, we evaluate the energy at the outer event horizon of
the black holes.
| [
{
"created": "Tue, 7 May 2002 22:46:02 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Jun 2002 21:57:45 GMT",
"version": "v2"
},
{
"created": "Mon, 17 Nov 2003 15:59:58 GMT",
"version": "v3"
}
] | 2009-11-07 | [
[
"da Rocha-Neto",
"J. F.",
""
],
[
"Castello-Branco",
"K. H.",
""
]
] | In the context of the Hamiltonian formulation of the teleparallel equivalent of general relativity we compute the gravitational energy of Kerr and Kerr Anti-de Sitter (Kerr-AdS) space-times. The present calculation is carried out by means of an expression for the energy of the gravitational field that naturally arises from the integral form of the constraint equations of the formalism. In each case, the energy is exactly computed for finite and arbitrary spacelike two-spheres, without any restriction on the metric parameters. In particular, we evaluate the energy at the outer event horizon of the black holes. |
1606.04654 | Cosimo Bambi | Yueying Ni, Menglei Zhou, Alejandro Cardenas-Avendano, Cosimo Bambi,
Carlos A.R. Herdeiro, Eugen Radu | Iron K$\alpha$ line of Kerr black holes with scalar hair | 1+18 pages, 9 figures. v2: refereed version | JCAP 1607:049,2016 | 10.1088/1475-7516/2016/07/049 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, a family of hairy black holes in 4-dimensional Einstein gravity
minimally coupled to a complex, massive scalar field was discovered~\cite{hbh}.
Besides the mass $M$ and spin angular momentum $J$, these objects are
characterized by a Noether charge $Q$, measuring the amount of scalar hair,
which is not associated to a Gauss law and cannot be measured at spatial
infinity. Introducing a dimensionless scalar hair parameter $q$, ranging from 0
to 1, we recover (a subset of) Kerr black holes for $q=0$ and a family of
rotating boson stars for $q=1$. In the present paper, we explore the
possibility of measuring $q$ for astrophysical black holes with current and
future X-ray missions. We study the iron K$\alpha$ line expected in the
reflection spectrum of such hairy black holes and we simulate observations with
Suzaku and eXTP. As a proof of concept, we point out, by analyzing a sample of
hairy black holes, that current observations can already constrain the scalar
hair parameter $q$, because black holes with $q$ close to 1 would have iron
lines definitively different from those we observe in the available data. We
conclude that a detailed scanning of the full space of solutions, together with
data from the future X-ray missions, like eXTP, will be able to put relevant
constraints on the astrophysical realization of Kerr black holes with scalar
hair.
| [
{
"created": "Wed, 15 Jun 2016 06:34:57 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Jul 2016 15:18:52 GMT",
"version": "v2"
}
] | 2016-07-29 | [
[
"Ni",
"Yueying",
""
],
[
"Zhou",
"Menglei",
""
],
[
"Cardenas-Avendano",
"Alejandro",
""
],
[
"Bambi",
"Cosimo",
""
],
[
"Herdeiro",
"Carlos A. R.",
""
],
[
"Radu",
"Eugen",
""
]
] | Recently, a family of hairy black holes in 4-dimensional Einstein gravity minimally coupled to a complex, massive scalar field was discovered~\cite{hbh}. Besides the mass $M$ and spin angular momentum $J$, these objects are characterized by a Noether charge $Q$, measuring the amount of scalar hair, which is not associated to a Gauss law and cannot be measured at spatial infinity. Introducing a dimensionless scalar hair parameter $q$, ranging from 0 to 1, we recover (a subset of) Kerr black holes for $q=0$ and a family of rotating boson stars for $q=1$. In the present paper, we explore the possibility of measuring $q$ for astrophysical black holes with current and future X-ray missions. We study the iron K$\alpha$ line expected in the reflection spectrum of such hairy black holes and we simulate observations with Suzaku and eXTP. As a proof of concept, we point out, by analyzing a sample of hairy black holes, that current observations can already constrain the scalar hair parameter $q$, because black holes with $q$ close to 1 would have iron lines definitively different from those we observe in the available data. We conclude that a detailed scanning of the full space of solutions, together with data from the future X-ray missions, like eXTP, will be able to put relevant constraints on the astrophysical realization of Kerr black holes with scalar hair. |
gr-qc/0610078 | Gamal Nashed G.L. | Gamal G.L. Nashed and Mohamed M. Mourad | Energy and Momentum of a Stationary Beam of Light in the New General
Relativity | 10 pages Latex | Nuovo Cim.B120:1307-1312,2005 | 10.1393/ncb/i2005-10169-1 | null | gr-qc | null | We give an exact solution to the gravitational field in the new general
relativity. The solution creates Bonnor spacetime. This spacetime describes the
gravitational field of a stationary beam of light. The energy and momentum of
this solution is calculated using the energy-momentum complex given by
M{\o}ller in (1978) within the framework of the Weitzenb{\rm $\ddot{o}$}ck
spacetime.
| [
{
"created": "Mon, 16 Oct 2006 09:54:54 GMT",
"version": "v1"
}
] | 2010-11-11 | [
[
"Nashed",
"Gamal G. L.",
""
],
[
"Mourad",
"Mohamed M.",
""
]
] | We give an exact solution to the gravitational field in the new general relativity. The solution creates Bonnor spacetime. This spacetime describes the gravitational field of a stationary beam of light. The energy and momentum of this solution is calculated using the energy-momentum complex given by M{\o}ller in (1978) within the framework of the Weitzenb{\rm $\ddot{o}$}ck spacetime. |
0903.3449 | Jose Ademir Sales Lima | M. A. S. Nobre, M. R. de Garcia Maia, J. C. Carvalho, J. A. S. Lima | Inhomogeneus Inflation and Cosmic no-Hair Conjecture | 8 pages, no figue | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The cosmic no hair conjecture is tested for a large class of inhomogeneous
cosmologies with a positive cosmological constant. Firstly, we derive a new
class of exact inhomogeneous cosmological solutions whose matter content of the
models is formed by a mixture of two interacting simple fluids plus a
cosmological Lambda-term. These models generalize the de Sitter spacetime and
the inhomogeneous two-fluid Szekeres-type cosmologies derived by Lima and
Tiomno. Finally, we show that the late time behaviour of our solutions is in
agreement with the "cosmic no hair theorem" of Hawking and Moss.
| [
{
"created": "Fri, 20 Mar 2009 04:16:36 GMT",
"version": "v1"
}
] | 2009-03-23 | [
[
"Nobre",
"M. A. S.",
""
],
[
"Maia",
"M. R. de Garcia",
""
],
[
"Carvalho",
"J. C.",
""
],
[
"Lima",
"J. A. S.",
""
]
] | The cosmic no hair conjecture is tested for a large class of inhomogeneous cosmologies with a positive cosmological constant. Firstly, we derive a new class of exact inhomogeneous cosmological solutions whose matter content of the models is formed by a mixture of two interacting simple fluids plus a cosmological Lambda-term. These models generalize the de Sitter spacetime and the inhomogeneous two-fluid Szekeres-type cosmologies derived by Lima and Tiomno. Finally, we show that the late time behaviour of our solutions is in agreement with the "cosmic no hair theorem" of Hawking and Moss. |
1202.1818 | Joshua S. Schiffrin | Joshua S. Schiffrin and Robert M. Wald | Measure and Probability in Cosmology | 43 pages, 2 figures | Phys.Rev.D.86.023521,2012 | 10.1103/PhysRevD.86.023521 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | General relativity has a Hamiltonian formulation, which formally provides a
canonical (Liouville) measure on the space of solutions. In ordinary
statistical physics, the Liouville measure is used to compute probabilities of
macrostates, and it would seem natural to use the similar measure arising in
general relativity to compute probabilities in cosmology, such as the
probability that the universe underwent an era of inflation. Indeed, a number
of authors have used the restriction of this measure to the space of
homogeneous and isotropic universes with scalar field matter
(minisuperspace)---namely, the Gibbons-Hawking-Stewart measure---to make
arguments about the likelihood of inflation. We argue here that there are at
least four major difficulties with using the measure of general relativity to
make probability arguments in cosmology: (1) Equilibration does not occur on
cosmological length scales. (2) Even in the minisuperspace case, the measure of
phase space is infinite and the computation of probabilities depends very
strongly on how the infinity is regulated. (3) The inhomogeneous degrees of
freedom must be taken into account (we illustrate how) even if one is
interested only in universes that are very nearly homogeneous. The measure
depends upon how the infinite number of degrees of freedom are truncated, and
how one defines "nearly homogeneous." (4) In a universe where the second law of
thermodynamics holds, one cannot make use of our knowledge of the present state
of the universe to "retrodict" the likelihood of past conditions.
| [
{
"created": "Wed, 8 Feb 2012 20:56:57 GMT",
"version": "v1"
}
] | 2012-08-16 | [
[
"Schiffrin",
"Joshua S.",
""
],
[
"Wald",
"Robert M.",
""
]
] | General relativity has a Hamiltonian formulation, which formally provides a canonical (Liouville) measure on the space of solutions. In ordinary statistical physics, the Liouville measure is used to compute probabilities of macrostates, and it would seem natural to use the similar measure arising in general relativity to compute probabilities in cosmology, such as the probability that the universe underwent an era of inflation. Indeed, a number of authors have used the restriction of this measure to the space of homogeneous and isotropic universes with scalar field matter (minisuperspace)---namely, the Gibbons-Hawking-Stewart measure---to make arguments about the likelihood of inflation. We argue here that there are at least four major difficulties with using the measure of general relativity to make probability arguments in cosmology: (1) Equilibration does not occur on cosmological length scales. (2) Even in the minisuperspace case, the measure of phase space is infinite and the computation of probabilities depends very strongly on how the infinity is regulated. (3) The inhomogeneous degrees of freedom must be taken into account (we illustrate how) even if one is interested only in universes that are very nearly homogeneous. The measure depends upon how the infinite number of degrees of freedom are truncated, and how one defines "nearly homogeneous." (4) In a universe where the second law of thermodynamics holds, one cannot make use of our knowledge of the present state of the universe to "retrodict" the likelihood of past conditions. |
gr-qc/0511080 | Aleksandar Mikovic | A. Mikovic | Spin Foam Models from the Tetrad Integration | 6 pages, based on the talk presented at the ERE05 meeting, September
6-10, 2005, Oviedo | AIP Conf.Proc.841:523-527,2006 | 10.1063/1.2218228 | null | gr-qc | null | We describe a class of spin foam models of four-dimensional quantum gravity
which is based on the integration of the tetrad one-forms in the path integral
for the Palatini action of General Relativity. In the Euclidian gravity case
this class of models can be understood as a modification of the Barrett-Crane
spin foam model. Fermionic matter can be coupled by using the path integral
with sources for the tetrads and the spin connection, and the corresponding
state sum is based on a spin foam where both the edges and the faces are
colored independently with the irreducible representations of the spacetime
rotations group.
| [
{
"created": "Tue, 15 Nov 2005 14:35:52 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Mikovic",
"A.",
""
]
] | We describe a class of spin foam models of four-dimensional quantum gravity which is based on the integration of the tetrad one-forms in the path integral for the Palatini action of General Relativity. In the Euclidian gravity case this class of models can be understood as a modification of the Barrett-Crane spin foam model. Fermionic matter can be coupled by using the path integral with sources for the tetrads and the spin connection, and the corresponding state sum is based on a spin foam where both the edges and the faces are colored independently with the irreducible representations of the spacetime rotations group. |
2012.10465 | Jakub Bilski | Jakub Bilski | Lie algebra of Ashtekar-Barbero connection operators | 4 pages | null | null | null | gr-qc hep-lat hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Holonomies of the Ashtekar-Barbero connection can be considered as abstract
elements of a Lie group exponentially mapped from their connections
representation. This idea provides a possibility to compare the geometric and
algebraic properties of these objects. The result allows to identify the
next-to-the-leading-order terms in the geometric and algebraic expansion of a
holonomy. This identification leads to the verification of the related Hilbert
space formulation. If states are the representations of the holonomy's symmetry
group, they preserve gauge transformations according to Wigner's theorem. Thus,
the spin network in loop quantum gravity satisfies this theorem. Moreover, the
considered identification of the different expansions ensures the reality of
the Ashtekar connection. Only the holonomies of real connections lead to the
formulation of states that satisfy Wigner's theorem.
| [
{
"created": "Fri, 18 Dec 2020 19:00:41 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Feb 2021 18:07:05 GMT",
"version": "v2"
}
] | 2021-02-19 | [
[
"Bilski",
"Jakub",
""
]
] | Holonomies of the Ashtekar-Barbero connection can be considered as abstract elements of a Lie group exponentially mapped from their connections representation. This idea provides a possibility to compare the geometric and algebraic properties of these objects. The result allows to identify the next-to-the-leading-order terms in the geometric and algebraic expansion of a holonomy. This identification leads to the verification of the related Hilbert space formulation. If states are the representations of the holonomy's symmetry group, they preserve gauge transformations according to Wigner's theorem. Thus, the spin network in loop quantum gravity satisfies this theorem. Moreover, the considered identification of the different expansions ensures the reality of the Ashtekar connection. Only the holonomies of real connections lead to the formulation of states that satisfy Wigner's theorem. |
gr-qc/0607081 | Sean A. Hayward | Sean A. Hayward | Conservation laws for dynamical black holes | 4 revtex4 pages, 3 eps figures, various improvements in line with
longer article | null | null | null | gr-qc | null | An essentially complete new paradigm for dynamical black holes in terms of
trapping horizons is presented, including dynamical versions of the physical
quantities and laws which were considered important in the classical paradigm
for black holes in terms of Killing or event horizons. Three state functions
are identified as surface integrals over marginal surfaces: irreducible mass,
angular momentum and charge. There are three corresponding conservation laws,
expressing the rate of change of the state function in terms of flux integrals,
or equivalently as divergence laws for associated conserved currents. The
currents of energy and angular momentum include the matter energy tensor in a
physically appropriate way, plus terms attributable to an effective energy
tensor for gravitational radiation. Four other state functions are derived: an
effective energy, surface gravity, angular speed and electric potential. There
follows a dynamical version of the so-called first law of black-hole mechanics.
A corresponding zeroth law holds for null trapping horizons.
| [
{
"created": "Thu, 20 Jul 2006 17:39:14 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Sep 2006 11:16:45 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Hayward",
"Sean A.",
""
]
] | An essentially complete new paradigm for dynamical black holes in terms of trapping horizons is presented, including dynamical versions of the physical quantities and laws which were considered important in the classical paradigm for black holes in terms of Killing or event horizons. Three state functions are identified as surface integrals over marginal surfaces: irreducible mass, angular momentum and charge. There are three corresponding conservation laws, expressing the rate of change of the state function in terms of flux integrals, or equivalently as divergence laws for associated conserved currents. The currents of energy and angular momentum include the matter energy tensor in a physically appropriate way, plus terms attributable to an effective energy tensor for gravitational radiation. Four other state functions are derived: an effective energy, surface gravity, angular speed and electric potential. There follows a dynamical version of the so-called first law of black-hole mechanics. A corresponding zeroth law holds for null trapping horizons. |
1911.04539 | Miguel Cruz | Miguel Cruz, Norman Cruz and Samuel Lepe | Unified dissipative dark matter model in a non linear Israel-Stewart
theory | New results were found and the core of the paper changed completely.
Now we contrast the fitting of the exact solution in the non linear approach
against LCDM model using supernovae type Ia data | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we study the Statefinder and $Om(x)$ diagnoses of an exact
solution of a unified dissipative dark matter model in the framework the
Israel-Stewart theory and its non linear extension, considering the condition
of positive entropy production. The implementation of two diagnoses in the pair
of solutions reveal that both solutions can emulate the $\Lambda$CDM model at
some stage of the cosmic evolution and behave as quintessence dark energy. The
stability of both solutions is discussed from the point of view of the
Liapunov's method, showing that they are asymptotic stable. Additionally we
show that the solutions are also stable under small perturbations. A simple
analysis of the solutions with the use of observational data suggests that the
non linear regime could lead to a inconsistencies-free scenario, i.e., in
agreement with the bounds obtained from the perturbative analysis for the
velocity of bulk viscous perturbations.
| [
{
"created": "Mon, 11 Nov 2019 19:47:20 GMT",
"version": "v1"
},
{
"created": "Sat, 18 Sep 2021 03:34:11 GMT",
"version": "v2"
}
] | 2021-09-21 | [
[
"Cruz",
"Miguel",
""
],
[
"Cruz",
"Norman",
""
],
[
"Lepe",
"Samuel",
""
]
] | In this paper we study the Statefinder and $Om(x)$ diagnoses of an exact solution of a unified dissipative dark matter model in the framework the Israel-Stewart theory and its non linear extension, considering the condition of positive entropy production. The implementation of two diagnoses in the pair of solutions reveal that both solutions can emulate the $\Lambda$CDM model at some stage of the cosmic evolution and behave as quintessence dark energy. The stability of both solutions is discussed from the point of view of the Liapunov's method, showing that they are asymptotic stable. Additionally we show that the solutions are also stable under small perturbations. A simple analysis of the solutions with the use of observational data suggests that the non linear regime could lead to a inconsistencies-free scenario, i.e., in agreement with the bounds obtained from the perturbative analysis for the velocity of bulk viscous perturbations. |
1209.2917 | Farook Rahaman | Farook Rahaman, P. K. F. Kuhfittig, Saibal Ray and Safiqul Islam | Searching for higher dimensional wormholes with noncommutative geometry | 13 pages and 10 figures. A typos in the title has been corrected.
Published in Phys.Rev.D | Phys. Rev. D 86, 106010 (2012) | 10.1103/PhysRevD.86.106010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Noncommutative geometry, an offshoot of string theory, replaces point-like
structures with smeared objects and has recently been extended to higher
dimensions. The purpose of this letter is to obtain wormhole solutions with
this extended noncommutative geometry as a background. It is found through this
investigation that wormhole solutions exist in the usual four, as well as in
five dimensions, but they do not exist in higher-dimensional spacetimes.
| [
{
"created": "Wed, 12 Sep 2012 14:27:30 GMT",
"version": "v1"
},
{
"created": "Sun, 4 Nov 2012 16:24:05 GMT",
"version": "v2"
},
{
"created": "Thu, 29 Nov 2012 13:10:02 GMT",
"version": "v3"
}
] | 2012-11-30 | [
[
"Rahaman",
"Farook",
""
],
[
"Kuhfittig",
"P. K. F.",
""
],
[
"Ray",
"Saibal",
""
],
[
"Islam",
"Safiqul",
""
]
] | Noncommutative geometry, an offshoot of string theory, replaces point-like structures with smeared objects and has recently been extended to higher dimensions. The purpose of this letter is to obtain wormhole solutions with this extended noncommutative geometry as a background. It is found through this investigation that wormhole solutions exist in the usual four, as well as in five dimensions, but they do not exist in higher-dimensional spacetimes. |
2209.15426 | Grigory Volovik | G.E. Volovik | Dimensionless physics: Planck constant as an element of Minkowski metric | 11 pages, no figures, version accepted in JETP Letters, arXiv admin
note: text overlap with arXiv:2207.05754 | null | 10.1134/S0021364022603013 | null | gr-qc cond-mat.other hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Diakonov theory of quantum gravity, in which tetrads emerge as the bilinear
combinations of the fermionis fields,\cite{Diakonov2011} suggests that in
general relativity the metric may have dimension 2, i.e.
$[g_{\mu\nu}]=1/[L]^2$. Several other approaches to quantum gravity, including
the model of superplastic vacuum and $BF$-theories of gravity support this
suggesuion. The important consequence of such metric dimension is that all the
diffeomorphism invariant quantities are dimensionless for any dimension of
spacetime. These include the action $S$, interval $s$, cosmological constant
$\Lambda$, scalar curvature $R$, scalar field $\Phi$, etc. Here we are trying
to further exploit the Diakonov idea, and consider the dimension of the Planck
constant. The application of the Diakonov theory suggests that the Planck
constant $\hbar$ is the parameter of the Minkowski metric. The Minkowski
parameter $\hbar$ is invariant only under Lorentz transformations, and is not
diffeomorphism invariant. As a result the Planck constant $\hbar$ has nonzero
dimension -- the dimension of length [L]. Whether this Planck constant length
is related to the Planck length scale, is an open question. In principle there
can be different Minkowski vacua with their own values of the parameter
$\hbar$. Then in the thermal contact between the two vacua their temperatures
obey the analog of the Tolman law: $\hbar_1/T_1= \hbar_2/T_2$.
| [
{
"created": "Fri, 30 Sep 2022 17:40:56 GMT",
"version": "v1"
},
{
"created": "Sun, 9 Oct 2022 17:42:20 GMT",
"version": "v2"
},
{
"created": "Sun, 27 Nov 2022 15:48:38 GMT",
"version": "v3"
},
{
"created": "Sun, 4 Dec 2022 15:01:09 GMT",
"version": "v4"
},
{
"cre... | 2023-02-15 | [
[
"Volovik",
"G. E.",
""
]
] | Diakonov theory of quantum gravity, in which tetrads emerge as the bilinear combinations of the fermionis fields,\cite{Diakonov2011} suggests that in general relativity the metric may have dimension 2, i.e. $[g_{\mu\nu}]=1/[L]^2$. Several other approaches to quantum gravity, including the model of superplastic vacuum and $BF$-theories of gravity support this suggesuion. The important consequence of such metric dimension is that all the diffeomorphism invariant quantities are dimensionless for any dimension of spacetime. These include the action $S$, interval $s$, cosmological constant $\Lambda$, scalar curvature $R$, scalar field $\Phi$, etc. Here we are trying to further exploit the Diakonov idea, and consider the dimension of the Planck constant. The application of the Diakonov theory suggests that the Planck constant $\hbar$ is the parameter of the Minkowski metric. The Minkowski parameter $\hbar$ is invariant only under Lorentz transformations, and is not diffeomorphism invariant. As a result the Planck constant $\hbar$ has nonzero dimension -- the dimension of length [L]. Whether this Planck constant length is related to the Planck length scale, is an open question. In principle there can be different Minkowski vacua with their own values of the parameter $\hbar$. Then in the thermal contact between the two vacua their temperatures obey the analog of the Tolman law: $\hbar_1/T_1= \hbar_2/T_2$. |
2302.03367 | Andrea Geralico | D. Bini, A. Geralico, R. T. Jantzen | Wedging spacetime principal null directions | 24 pages, no figures | null | 10.1142/S0219887823501499 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Taking wedge products of the $p$ distinct principal null directions
associated with the eigen-bivectors of the Weyl tensor associated with the
Petrov classification, when linearly independent, one is able to express them
in terms of the eigenvalues governing this decomposition. We study here
algebraic and differential properties of such $p$-forms by completing previous
geometrical results concerning type I spacetimes and extending that analysis to
algebraically special spacetimes with at least 2 distinct principal null
directions. A number of vacuum and nonvacuum spacetimes are examined to
illustrate the general treatment.
| [
{
"created": "Tue, 7 Feb 2023 10:20:13 GMT",
"version": "v1"
}
] | 2023-07-26 | [
[
"Bini",
"D.",
""
],
[
"Geralico",
"A.",
""
],
[
"Jantzen",
"R. T.",
""
]
] | Taking wedge products of the $p$ distinct principal null directions associated with the eigen-bivectors of the Weyl tensor associated with the Petrov classification, when linearly independent, one is able to express them in terms of the eigenvalues governing this decomposition. We study here algebraic and differential properties of such $p$-forms by completing previous geometrical results concerning type I spacetimes and extending that analysis to algebraically special spacetimes with at least 2 distinct principal null directions. A number of vacuum and nonvacuum spacetimes are examined to illustrate the general treatment. |
gr-qc/0009093 | E. Fabri | A. De Felice, E. Fabri | The Friedmann universe of dust by Regge Calculus: study of its ending
point | 5 figures (EPS) | null | null | null | gr-qc | null | We develop an evolution scheme, based on Sorkin algorithm, to evolve the most
complex regular tridimensional polytope, the 600-cell. This application has
been already studied before and all authors found a stop point for the
evolution of the spatial section. In our opinion a clear and satisfactory
meaning to this behaviour has not been given. In this paper we propose a reason
why the evolution of the 600-cell stops when its volume is still far from 0. We
find that the 600-cell meets a causality-breaking singularity of space-time. We
study the nature of this singularity by embedding the 600-cell into a
five-dimensional Lorentzian manifold. We fit 600-cell's evolution with a
continuos metric and study it as a solution of Einstein equations.
| [
{
"created": "Wed, 27 Sep 2000 07:47:20 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"De Felice",
"A.",
""
],
[
"Fabri",
"E.",
""
]
] | We develop an evolution scheme, based on Sorkin algorithm, to evolve the most complex regular tridimensional polytope, the 600-cell. This application has been already studied before and all authors found a stop point for the evolution of the spatial section. In our opinion a clear and satisfactory meaning to this behaviour has not been given. In this paper we propose a reason why the evolution of the 600-cell stops when its volume is still far from 0. We find that the 600-cell meets a causality-breaking singularity of space-time. We study the nature of this singularity by embedding the 600-cell into a five-dimensional Lorentzian manifold. We fit 600-cell's evolution with a continuos metric and study it as a solution of Einstein equations. |
0907.2339 | Trevor W. Marshall | Trevor W. Marshall | The gravitational collapse of a dust ball | 13 pages, 2 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that the description of collapse given by the classic model of
Oppenheimer and Snyder fails to satisfy a crucial matching condition at the
surface of the ball. After correcting the model so that the interior and
exterior metrics match correctly, it is established that the contraction
process stops at the Schwarzschild radius, that there is an accumulation of
particles at the surface of the ball, and that in the limit of infinite time
lapse the density of particles at the surface becomes infinite. A black hole
cannot form. This result confirms the judgements of both Einstein and Eddington
about gravitational collapse when the collapse velocity approaches that of
light.
| [
{
"created": "Tue, 14 Jul 2009 12:36:57 GMT",
"version": "v1"
}
] | 2009-07-15 | [
[
"Marshall",
"Trevor W.",
""
]
] | It is shown that the description of collapse given by the classic model of Oppenheimer and Snyder fails to satisfy a crucial matching condition at the surface of the ball. After correcting the model so that the interior and exterior metrics match correctly, it is established that the contraction process stops at the Schwarzschild radius, that there is an accumulation of particles at the surface of the ball, and that in the limit of infinite time lapse the density of particles at the surface becomes infinite. A black hole cannot form. This result confirms the judgements of both Einstein and Eddington about gravitational collapse when the collapse velocity approaches that of light. |
gr-qc/9908078 | Masafumi Seriu | Masafumi Seriu | Space of spaces as a metric space | To appear in Communications in Mathematical Physics. 20 pages | Commun.Math.Phys. 209 (2000) 393-405 | 10.1007/s002200050025 | null | gr-qc | null | In spacetime physics, we frequently need to consider a set of all spaces
(`universes') as a whole. In particular, the concept of `closeness' between
spaces is essential. However, there has been no established mathematical theory
so far which deals with a space of spaces in a suitable manner for spacetime
physics.
Based on the scheme of the spectral representation of geometry, we construct
a space of all compact Riemannian manifolds equipped with the spectral measure
of closeness. We show that this space of all spaces can be regarded as a metric
space. We also show other desirable properties of this space, such as the
partition of unity, locally-compactness and the second countability. These
facts show that this space of all spaces can be a basic arena for spacetime
physics.
| [
{
"created": "Tue, 31 Aug 1999 13:20:47 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Seriu",
"Masafumi",
""
]
] | In spacetime physics, we frequently need to consider a set of all spaces (`universes') as a whole. In particular, the concept of `closeness' between spaces is essential. However, there has been no established mathematical theory so far which deals with a space of spaces in a suitable manner for spacetime physics. Based on the scheme of the spectral representation of geometry, we construct a space of all compact Riemannian manifolds equipped with the spectral measure of closeness. We show that this space of all spaces can be regarded as a metric space. We also show other desirable properties of this space, such as the partition of unity, locally-compactness and the second countability. These facts show that this space of all spaces can be a basic arena for spacetime physics. |
1310.3104 | Valentin Rudenko | A.V. Gusev, V.N. Rudenko, I.S Yudin | Low frequency signals of large scale GW-interferometers | 29 pages, 1 figure, submitted to Classical and Quantum Gravity | null | 10.1134/S1063776114100033 | null | gr-qc physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Application of the large scale gravitational wave interferometers for
measurement of geophysical signals at very low frequencies is considered.
Analysis is concentrated on the mechanism of penetration of quasistatic
geophysical perturbation through the main interferometer output. It is shown
that it has a parametrical nature resulted in slow variations of the optical
transfer function of the interferometer. Geophysical modulation index is
calculated for any harmonical component of the output spectrum, but mainly for
a photon circulation frequency appeared in the case of stochastic illumination
of modes neighbour to the central resonance. Value of the effect is estimated
for different operational regimes of the device. For improvement of geophysical
signal readout a modernization of the instrument with using of two component
resonance optical pump is proposed and a correspondent calculation is carried
out. Numerical estimations for different regimes of the setup are given
together with discussion of possible application for measuring some weak
gravitational effects.
| [
{
"created": "Fri, 11 Oct 2013 12:30:07 GMT",
"version": "v1"
}
] | 2015-06-17 | [
[
"Gusev",
"A. V.",
""
],
[
"Rudenko",
"V. N.",
""
],
[
"Yudin",
"I. S",
""
]
] | Application of the large scale gravitational wave interferometers for measurement of geophysical signals at very low frequencies is considered. Analysis is concentrated on the mechanism of penetration of quasistatic geophysical perturbation through the main interferometer output. It is shown that it has a parametrical nature resulted in slow variations of the optical transfer function of the interferometer. Geophysical modulation index is calculated for any harmonical component of the output spectrum, but mainly for a photon circulation frequency appeared in the case of stochastic illumination of modes neighbour to the central resonance. Value of the effect is estimated for different operational regimes of the device. For improvement of geophysical signal readout a modernization of the instrument with using of two component resonance optical pump is proposed and a correspondent calculation is carried out. Numerical estimations for different regimes of the setup are given together with discussion of possible application for measuring some weak gravitational effects. |
1401.2026 | Stefan Hollands | Stefan Hollands and Robert M. Wald | Quantum fields in curved spacetime | 77 pages, 5 figures, extended version of invited contribution to "100
Years of General Relativity" monograph series | null | 10.1016/j.physrep.2015.02.001 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review the theory of quantum fields propagating in an arbitrary,
classical, globally hyperbolic spacetime. Our review emphasizes the conceptual
issues arising in the formulation of the theory and presents known results in a
mathematically precise way. Particular attention is paid to the distributional
nature of quantum fields, to their local and covariant character, and to
microlocal spectrum conditions satisfied by physically reasonable states. We
review the Unruh and Hawking effects for free fields, as well as the behavior
of free fields in deSitter spacetime and FLRW spacetimes with an exponential
phase of expansion. We review how nonlinear observables of a free field, such
as the stress-energy tensor, are defined, as well as time-ordered-products. The
"renormalization ambiguities" involved in the definition of time-ordered
products are fully characterized. Interacting fields are then perturbatively
constructed. Our main focus is on the theory of a scalar field, but a brief
discussion of gauge fields is included. We conclude with a brief discussion of
a possible approach towards a nonperturbative formulation of quantum field
theory in curved spacetime and some remarks on the formulation of quantum
gravity.
| [
{
"created": "Thu, 9 Jan 2014 15:15:29 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Jun 2014 07:56:57 GMT",
"version": "v2"
}
] | 2015-06-18 | [
[
"Hollands",
"Stefan",
""
],
[
"Wald",
"Robert M.",
""
]
] | We review the theory of quantum fields propagating in an arbitrary, classical, globally hyperbolic spacetime. Our review emphasizes the conceptual issues arising in the formulation of the theory and presents known results in a mathematically precise way. Particular attention is paid to the distributional nature of quantum fields, to their local and covariant character, and to microlocal spectrum conditions satisfied by physically reasonable states. We review the Unruh and Hawking effects for free fields, as well as the behavior of free fields in deSitter spacetime and FLRW spacetimes with an exponential phase of expansion. We review how nonlinear observables of a free field, such as the stress-energy tensor, are defined, as well as time-ordered-products. The "renormalization ambiguities" involved in the definition of time-ordered products are fully characterized. Interacting fields are then perturbatively constructed. Our main focus is on the theory of a scalar field, but a brief discussion of gauge fields is included. We conclude with a brief discussion of a possible approach towards a nonperturbative formulation of quantum field theory in curved spacetime and some remarks on the formulation of quantum gravity. |
0909.2436 | Edward Anderson | Edward Anderson and Anne Franzen | Quantum Cosmological Metroland Model | null | Class.Quant.Grav.27:045009,2010 | 10.1088/0264-9381/27/4/045009 | ITP-UU_09/36, SPIN-09/33 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Relational particle mechanics is useful for modelling whole-universe issues
such as quantum cosmology or the problem of time in quantum gravity, including
some aspects outside the reach of comparably complex minisuperspace models. In
this article, we consider the mechanics of pure shape and not scale of 4
particles on a line, so that the only physically significant quantities are
ratios of relative separations between the constituents' physical objects. Many
of our ideas and workings extend to the N-particle case. As such models'
configurations resemble depictions of metro lines in public transport maps, we
term them `N-stop metrolands'. This 4-stop model's configuration space is a
2-sphere, from which our metroland mechanics interpretation is via the `cubic'
tessellation. This model yields conserved quantities which are mathematically
SO(3) objects like angular momenta but are physically relative dilational
momenta (i.e. coordinates dotted with momenta). We provide and interpret
various exact and approximate classical and quantum solutions for 4-stop
metroland; from these results one can construct expectations and spreads of
shape operators that admit interpretations as relative sizes and the
`homogeneity of the model universe's contents', and also objects of
significance for the problem of time in quantum gravity (e.g. in the naive
Schrodinger and records theory timeless approaches).
| [
{
"created": "Mon, 14 Sep 2009 10:06:22 GMT",
"version": "v1"
}
] | 2010-03-25 | [
[
"Anderson",
"Edward",
""
],
[
"Franzen",
"Anne",
""
]
] | Relational particle mechanics is useful for modelling whole-universe issues such as quantum cosmology or the problem of time in quantum gravity, including some aspects outside the reach of comparably complex minisuperspace models. In this article, we consider the mechanics of pure shape and not scale of 4 particles on a line, so that the only physically significant quantities are ratios of relative separations between the constituents' physical objects. Many of our ideas and workings extend to the N-particle case. As such models' configurations resemble depictions of metro lines in public transport maps, we term them `N-stop metrolands'. This 4-stop model's configuration space is a 2-sphere, from which our metroland mechanics interpretation is via the `cubic' tessellation. This model yields conserved quantities which are mathematically SO(3) objects like angular momenta but are physically relative dilational momenta (i.e. coordinates dotted with momenta). We provide and interpret various exact and approximate classical and quantum solutions for 4-stop metroland; from these results one can construct expectations and spreads of shape operators that admit interpretations as relative sizes and the `homogeneity of the model universe's contents', and also objects of significance for the problem of time in quantum gravity (e.g. in the naive Schrodinger and records theory timeless approaches). |
2307.06813 | Antonio Vicente-Becerril | Ana Alonso-Serrano, Guillermo A. Mena Marugan and Antonio
Vicente-Becerril | Analytic Primordial Power Spectrum in the Dressed Metric Approach to
Loop Quantum Cosmology and Thermodynamics of Spacetime | 19 pages, 8 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the primordial power spectrum of cosmological tensor
perturbations in the dressed metric approach to Loop Quantum Cosmology. We
compute the background-dependent effective mass that affects their propagation
using the effective description of Loop Quantum Cosmology and show that this
mass can be approximated in different cosmological epochs by appropriate
analytic functions. Moreover, in each of those epochs we can analytically solve
the propagation of the perturbations, then obtaining the general solution
globally by continuity requirements. On the other hand, since there are regimes
far away from slow roll in the considered background evolution, the
Bunch-Davies state does not provide a privileged choice of vacuum that would
pick out a specific solution for the perturbations. Instead, we select the
state of these perturbations by a recently proposed criterion that removes
unwanted oscillations in the power spectrum. We compute the spectrum of this
vacuum and compare it with other spectra obtained in the literature, especially
with one corresponding to the hybrid approach to Loop Quantum Cosmology.
Finally, we notice that the same type of background dynamics is found in a
phenomenological approach to quantum gravity based on thermodynamics, allowing
in this case a free value for the tantamount of the critical density. Extending
the dressed metric proposal to this phenomenological model, one might expect a
similar form for the associated primordial power spectrum.
| [
{
"created": "Thu, 13 Jul 2023 15:27:01 GMT",
"version": "v1"
},
{
"created": "Sat, 27 Jul 2024 14:29:58 GMT",
"version": "v2"
}
] | 2024-07-30 | [
[
"Alonso-Serrano",
"Ana",
""
],
[
"Marugan",
"Guillermo A. Mena",
""
],
[
"Vicente-Becerril",
"Antonio",
""
]
] | We investigate the primordial power spectrum of cosmological tensor perturbations in the dressed metric approach to Loop Quantum Cosmology. We compute the background-dependent effective mass that affects their propagation using the effective description of Loop Quantum Cosmology and show that this mass can be approximated in different cosmological epochs by appropriate analytic functions. Moreover, in each of those epochs we can analytically solve the propagation of the perturbations, then obtaining the general solution globally by continuity requirements. On the other hand, since there are regimes far away from slow roll in the considered background evolution, the Bunch-Davies state does not provide a privileged choice of vacuum that would pick out a specific solution for the perturbations. Instead, we select the state of these perturbations by a recently proposed criterion that removes unwanted oscillations in the power spectrum. We compute the spectrum of this vacuum and compare it with other spectra obtained in the literature, especially with one corresponding to the hybrid approach to Loop Quantum Cosmology. Finally, we notice that the same type of background dynamics is found in a phenomenological approach to quantum gravity based on thermodynamics, allowing in this case a free value for the tantamount of the critical density. Extending the dressed metric proposal to this phenomenological model, one might expect a similar form for the associated primordial power spectrum. |
gr-qc/0612132 | Giovanni Venturi | G. Venturi | Broken Scale Invariance and Quintessence (a quarter of a century ago) | 3 pages, contribution to the proceedings of MG11, Berlin, 23-29 July,
2006 | null | null | null | gr-qc astro-ph hep-th | null | The cosmological consequences of a simple scalar field model for the
generation of Newton's constant through the spontaneous breaking of scale
invariance in a curved space-time are again presented and discussed. Such a
model leads to a consistent description wherein the introduction of matter
introduces a small perturbation on a de Sitter universe and a time dependence
of the gravitational coupling.
| [
{
"created": "Thu, 21 Dec 2006 11:06:57 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Venturi",
"G.",
""
]
] | The cosmological consequences of a simple scalar field model for the generation of Newton's constant through the spontaneous breaking of scale invariance in a curved space-time are again presented and discussed. Such a model leads to a consistent description wherein the introduction of matter introduces a small perturbation on a de Sitter universe and a time dependence of the gravitational coupling. |
1703.05574 | Yoshimasa Kurihara | Yoshimasa Kurihara | Nakanishi-Kugo-Ojima quantization of general relativity in Heisenberg
picture | 28 pages, 0 figure | The European Physical Journal Plus volume 136, Article number: 462
(2021) | 10.1140/epjp/s13360-021-01463-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Chern-Weil topological theory is applied to a classical formulation of
general relativity in four-dimensional spacetime. Einstein--Hilbert
gravitational action is shown to be invariant with respect to a novel
translation (co-translation) operator up to the total derivative; thus, a
topological invariant of a second Chern class exists owing to Chern-Weil
theory. Using topological insight, fundamental forms can be introduced as a
principal bundle of the spacetime manifold. Canonical quantization of general
relativity is performed in a Heisenberg picture using the Nakanishi-Kugo-Ojima
formalism in which a complete set of quantum Lagrangian and BRST
transformations including auxiliary and ghost fields is provided in a
self-consistent manner. An appropriate Hilbert space and physical states are
introduced into the theory, and the positivity of these physical states and the
unitarity of the transition matrix are ensured according to the Kugo-Ojima
theorem. The nonrenormalizability of quantum gravity is reconsidered under the
formulation proposed herein.
| [
{
"created": "Mon, 6 Mar 2017 20:38:03 GMT",
"version": "v1"
},
{
"created": "Tue, 30 Mar 2021 06:40:12 GMT",
"version": "v10"
},
{
"created": "Sun, 16 Apr 2017 06:31:17 GMT",
"version": "v2"
},
{
"created": "Mon, 1 May 2017 01:51:33 GMT",
"version": "v3"
},
{
"cr... | 2021-05-26 | [
[
"Kurihara",
"Yoshimasa",
""
]
] | The Chern-Weil topological theory is applied to a classical formulation of general relativity in four-dimensional spacetime. Einstein--Hilbert gravitational action is shown to be invariant with respect to a novel translation (co-translation) operator up to the total derivative; thus, a topological invariant of a second Chern class exists owing to Chern-Weil theory. Using topological insight, fundamental forms can be introduced as a principal bundle of the spacetime manifold. Canonical quantization of general relativity is performed in a Heisenberg picture using the Nakanishi-Kugo-Ojima formalism in which a complete set of quantum Lagrangian and BRST transformations including auxiliary and ghost fields is provided in a self-consistent manner. An appropriate Hilbert space and physical states are introduced into the theory, and the positivity of these physical states and the unitarity of the transition matrix are ensured according to the Kugo-Ojima theorem. The nonrenormalizability of quantum gravity is reconsidered under the formulation proposed herein. |
gr-qc/0305067 | John Klauder | John R. Klauder | Affine Quantum Gravity | latex, 6 pages, no figures | Int.J.Mod.Phys. D12 (2003) 1769-1774 | 10.1142/S0218271803003967 | null | gr-qc | null | A sketch of the affine quantum gravity program illustrates a different
perspective on several difficult issues of principle: metric positivity;
quantum anomalies; and nonrenormalizability.
| [
{
"created": "Sat, 17 May 2003 23:05:00 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Klauder",
"John R.",
""
]
] | A sketch of the affine quantum gravity program illustrates a different perspective on several difficult issues of principle: metric positivity; quantum anomalies; and nonrenormalizability. |
1903.04023 | Dirk Puetzfeld | Dirk Puetzfeld, Yuri N. Obukhov, Friedrich W. Hehl | Constitutive law of nonlocal gravity | 7 pages | Phys. Rev. D 99, 104013 (2019) | 10.1103/PhysRevD.99.104013 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the structure of a recent nonlocal generalization of Einstein's
theory of gravitation by Mashhoon et al. By means of a covariant technique, we
derive an expanded version of the nonlocality tensor which constitutes the
theory. At the lowest orders of approximation, this leads to a simplification
which sheds light on the fundamental structure of the theory and may prove
useful in the search for exact solutions of nonlocal gravity.
| [
{
"created": "Sun, 10 Mar 2019 17:03:28 GMT",
"version": "v1"
},
{
"created": "Thu, 9 May 2019 12:57:21 GMT",
"version": "v2"
}
] | 2019-05-10 | [
[
"Puetzfeld",
"Dirk",
""
],
[
"Obukhov",
"Yuri N.",
""
],
[
"Hehl",
"Friedrich W.",
""
]
] | We analyze the structure of a recent nonlocal generalization of Einstein's theory of gravitation by Mashhoon et al. By means of a covariant technique, we derive an expanded version of the nonlocality tensor which constitutes the theory. At the lowest orders of approximation, this leads to a simplification which sheds light on the fundamental structure of the theory and may prove useful in the search for exact solutions of nonlocal gravity. |
1002.4651 | Gil Jannes | C. Barcelo, L.J. Garay, G. Jannes | Quantum Non-Gravity and Stellar Collapse | 6 pages, 2 figures. v2: Partially restructured; potentially
observable consequence added. Several clarifications + 3 new references. To
appear in Found. of Phys | Found.Phys.41:1532-1541,2011 | 10.1007/s10701-011-9577-9 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Observational indications combined with analyses of analogue and emergent
gravity in condensed matter systems support the possibility that there might be
two distinct energy scales related to quantum gravity: the scale that sets the
onset of quantum gravitational effects $E_B$ (related to the Planck scale) and
the much higher scale $E_L$ signalling the breaking of Lorentz symmetry. We
suggest a natural interpretation for these two scales: $E_L$ is the energy
scale below which a special relativistic spacetime emerges, $E_B$ is the scale
below which this spacetime geometry becomes curved. This implies that the first
`quantum' gravitational effect around $E_B$ could simply be that gravity is
progressively switched off, leaving an effective Minkowski quantum field theory
up to much higher energies of the order of $E_L$. This scenario may have
important consequences for gravitational collapse, inasmuch as it opens up new
possibilities for the final state of stellar collapse other than an evaporating
black hole.
| [
{
"created": "Wed, 24 Feb 2010 23:24:50 GMT",
"version": "v1"
},
{
"created": "Tue, 21 Jun 2011 08:27:45 GMT",
"version": "v2"
}
] | 2011-08-01 | [
[
"Barcelo",
"C.",
""
],
[
"Garay",
"L. J.",
""
],
[
"Jannes",
"G.",
""
]
] | Observational indications combined with analyses of analogue and emergent gravity in condensed matter systems support the possibility that there might be two distinct energy scales related to quantum gravity: the scale that sets the onset of quantum gravitational effects $E_B$ (related to the Planck scale) and the much higher scale $E_L$ signalling the breaking of Lorentz symmetry. We suggest a natural interpretation for these two scales: $E_L$ is the energy scale below which a special relativistic spacetime emerges, $E_B$ is the scale below which this spacetime geometry becomes curved. This implies that the first `quantum' gravitational effect around $E_B$ could simply be that gravity is progressively switched off, leaving an effective Minkowski quantum field theory up to much higher energies of the order of $E_L$. This scenario may have important consequences for gravitational collapse, inasmuch as it opens up new possibilities for the final state of stellar collapse other than an evaporating black hole. |
gr-qc/0503119 | Keisuke Taniguchi | Masaru Shibata, Keisuke Taniguchi, and Koji Uryu | Merger of binary neutron stars with realistic equations of state in full
general relativity | Typos corrected, 2 references and comments on them added, 26 pages,
54 Postscript figures, Phys.Rev.D in press | Phys.Rev. D71 (2005) 084021 | 10.1103/PhysRevD.71.084021 | null | gr-qc astro-ph | null | We present numerical results of three-dimensional simulations for the merger
of binary neutron stars (BNSs) in full general relativity. Hybrid equations of
state (EOSs) are adopted to mimic realistic nuclear EOSs. In this approach, we
divide the EOSs into two parts, i.e., the thermal part and the cold part. For
the cold part, we assign a fitting formula for realistic EOSs of cold nuclear
matter slightly modifying the formula developed by Haensel and Potekhin. We
adopt the SLy and FPS EOSs for which the maximum allowed ADM mass of cold and
spherical neutron stars (NSs) is ~ 2.04Mo and 1.80Mo, respectively. Simulations
are performed for BNSs of the total ADM mass in the range between 2.4Mo and
2.8Mo with the rest-mass ratio Q_M to be in the range 0.9 < Q_M < 1. It is
found that if the total ADM mass of the system is larger than a threshold
M_{thr}, a black hole (BH) is promptly formed in the merger irrespective of the
mass ratios. In the other case, the outcome is a hypermassive NS of a large
ellipticity, which results from the large adiabatic index of the realistic EOSs
adopted. The value of M_{thr} depends on the EOS: ~ 2.7Mo and ~ 2.5Mo for the
SLy and FPS EOSs, respectively. Gravitational waves are computed in terms of a
gauge-invariant wave extraction technique. In the formation of the hypermassive
NS, quasiperiodic gravitational waves of a large amplitude and of frequency
between 3 and 4 kHz are emitted. The estimated emission time scale is < 100 ms,
after which the hypermassive NS collapses to a BH. Because of the long emission
time, the effective amplitude may be large enough to be detected by advanced
laser interferometric gravitational wave detectors if the distance to the
source is smaller than ~ 100 Mpc.
| [
{
"created": "Wed, 30 Mar 2005 16:54:13 GMT",
"version": "v1"
},
{
"created": "Sat, 9 Apr 2005 18:47:48 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Shibata",
"Masaru",
""
],
[
"Taniguchi",
"Keisuke",
""
],
[
"Uryu",
"Koji",
""
]
] | We present numerical results of three-dimensional simulations for the merger of binary neutron stars (BNSs) in full general relativity. Hybrid equations of state (EOSs) are adopted to mimic realistic nuclear EOSs. In this approach, we divide the EOSs into two parts, i.e., the thermal part and the cold part. For the cold part, we assign a fitting formula for realistic EOSs of cold nuclear matter slightly modifying the formula developed by Haensel and Potekhin. We adopt the SLy and FPS EOSs for which the maximum allowed ADM mass of cold and spherical neutron stars (NSs) is ~ 2.04Mo and 1.80Mo, respectively. Simulations are performed for BNSs of the total ADM mass in the range between 2.4Mo and 2.8Mo with the rest-mass ratio Q_M to be in the range 0.9 < Q_M < 1. It is found that if the total ADM mass of the system is larger than a threshold M_{thr}, a black hole (BH) is promptly formed in the merger irrespective of the mass ratios. In the other case, the outcome is a hypermassive NS of a large ellipticity, which results from the large adiabatic index of the realistic EOSs adopted. The value of M_{thr} depends on the EOS: ~ 2.7Mo and ~ 2.5Mo for the SLy and FPS EOSs, respectively. Gravitational waves are computed in terms of a gauge-invariant wave extraction technique. In the formation of the hypermassive NS, quasiperiodic gravitational waves of a large amplitude and of frequency between 3 and 4 kHz are emitted. The estimated emission time scale is < 100 ms, after which the hypermassive NS collapses to a BH. Because of the long emission time, the effective amplitude may be large enough to be detected by advanced laser interferometric gravitational wave detectors if the distance to the source is smaller than ~ 100 Mpc. |
1606.01262 | LVC Publications | The LIGO Scientific Collaboration and the Virgo Collaboration: B. P.
Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C.
Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M.
Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith,
B. Allen, A. Allocca, P. A. Altin, S. B. Anderson, W. G. Anderson, K. Arai,
M. C. Araya, C. C. Arceneaux, J. S. Areeda, N. Arnaud, K. G. Arun, S.
Ascenzi, G. Ashton, M. Ast, S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert,
S. Babak, P. Bacon, M. K. M. Bader, P. T. Baker, F. Baldaccini, G. Ballardin,
S. W. Ballmer, J. C. Barayoga, S. E. Barclay, B. C. Barish, D. Barker, F.
Barone, B. Barr, L. Barsotti, M. Barsuglia, D. Barta, J. Bartlett, I. Bartos,
R. Bassiri, A. Basti, J. C. Batch, C. Baune, V. Bavigadda, M. Bazzan, M.
Bejger, A. S. Bell, B. K. Berger, G. Bergmann, C. P. L. Berry, D. Bersanetti,
A. Bertolini, J. Betzwieser, S. Bhagwat, R. Bhandare, I. A. Bilenko, G.
Billingsley, J. Birch, R. Birney, S. Biscans, A. Bisht, M. Bitossi, C. Biwer,
M. A. Bizouard, J. K. Blackburn, C. D. Blair, D. G. Blair, R. M. Blair, S.
Bloemen, O. Bock, M. Boer, G. Bogaert, C. Bogan, A. Bohe, C. Bond, F. Bondu,
R. Bonnand, B. A. Boom, R. Bork, V. Boschi, S. Bose, Y. Bouffanais, A. Bozzi,
C. Bradaschia, P. R. Brady, V. B. Braginsky, M. Branchesi, J. E. Brau, T.
Briant, A. Brillet, M. Brinkmann, V. Brisson, P. Brockill, J. E. Broida, A.
F. Brooks, D. A. Brown, D. D. Brown, N. M. 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. Callister, E. Calloni, J. B. Camp, K. C. Cannon, J. Cao, C. D.
Capano, E. Capocasa, F. Carbognani, S. Caride, J. Casanueva Diaz, C.
Casentini, S. Caudill, M. Cavagli`a, F. Cavalier, R. Cavalieri, G. Cella, C.
B. Cepeda, L. Cerboni Baiardi, G. Cerretani, E. Cesarini, M. Chan, S. Chao,
P. Charlton, E. Chassande-Mottin, B. D. Cheeseboro, H. Y. Chen, Y. Chen, C.
Cheng, A. Chincarini, A. Chiummo, H. S. Cho, M. Cho, J. H. Chow, N.
Christensen, Q. Chu, S. Chua, S. Chung, G. Ciani, F. Clara, J. A. Clark, F.
Cleva, E. Coccia, P.-F. Cohadon, A. Colla, C. G. Collette, L. Cominsky, M.
Constancio Jr., A. Conte, L. Conti, D. Cook, T. R. Corbitt, N. Cornish, A.
Corsi, S. Cortese, C. A. Costa, M. W. Coughlin, S. B. Coughlin, J.-P. Coulon,
S. T. Countryman, P. Couvares, E. E. Cowan, D. M. Coward, M. J. Cowart, D. C.
Coyne, R. Coyne, K. Craig, J. D. E. Creighton, J. Cripe, S. G. Crowder, A.
Cumming, L. Cunningham, E. Cuoco, T. Dal Canton, S. L. Danilishin, S.
D'Antonio, K. Danzmann, N. S. Darman, A. Dasgupta, C. F. Da Silva Costa, V.
Dattilo, I. Dave, M. Davier, G. S. Davies, E. J. Daw, R. Day, S. De, D.
DeBra, G. Debreczeni, J. Degallaix, M. De Laurentis, S. Del'eglise, W. Del
Pozzo, T. Denker, T. Dent, V. Dergachev, R. De Rosa, R. T. DeRosa, R.
DeSalvo, R. C. Devine, S. Dhurandhar, M. C. D'iaz, L. Di Fiore, M. Di
Giovanni, T. Di Girolamo, A. Di Lieto, S. Di Pace, I. Di Palma, A. Di
Virgilio, V. Dolique, F. Donovan, K. L. Dooley, S. Doravari, R. Douglas, T.
P. Downes, M. Drago, R. W. P. Drever, J. C. Driggers, M. Ducrot, S. E. Dwyer,
T. B. Edo, M. C. Edwards, A. Effler, H.-B. Eggenstein, P. Ehrens, J.
Eichholz, S. S. Eikenberry, W. Engels, R. C. Essick, T. Etzel, M. Evans, T.
M. Evans, R. Everett, M. Factourovich, V. Fafone, H. Fair, S. Fairhurst, X.
Fan, Q. Fang, S. Farinon, B. Farr, W. M. Farr, M. Favata, M. Fays, H.
Fehrmann, M. M. Fejer, E. Fenyvesi, I. Ferrante, E. C. Ferreira, F. Ferrini,
F. Fidecaro, I. Fiori, D. Fiorucci, R. P. Fisher, R. Flaminio, M. Fletcher,
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. G. Gabbard, J. R. Gair,
L. Gammaitoni, S. G. Gaonkar, F. Garufi, G. Gaur, N. Gehrels, G. Gemme, P.
Geng, E. Genin, A. Gennai, J. George, L. Gergely, V. Germain, Abhirup Ghosh,
Archisman Ghosh, S. Ghosh, J. A. Giaime, K. D. Giardina, A. Giazotto, K.
Gill, A. Glaefke, E. Goetz, R. Goetz, L. Gondan, G. Gonz'alez, J. M. Gonzalez
Castro, A. Gopakumar, N. A. Gordon, M. L. Gorodetsky, S. E. Gossan, M.
Gosselin, R. Gouaty, A. Grado, C. Graef, P. B. Graff, M. Granata, A. Grant,
S. Gras, C. Gray, G. Greco, A. C. Green, P. Groot, H. Grote, S. Grunewald, G.
M. Guidi, X. Guo, A. Gupta, M. K. Gupta, K. E. Gushwa, E. K. Gustafson, R.
Gustafson, J. J. Hacker, B. R. Hall, E. D. Hall, G. Hammond, M. Haney, M. M.
Hanke, J. Hanks, C. Hanna, J. Hanson, T. Hardwick, J. Harms, G. M. Harry, I.
W. Harry, M. J. Hart, M. T. Hartman, C.-J. Haster, K. Haughian, A. Heidmann,
M. C. Heintze, H. Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, J.
Hennig, J. Henry, A. W. Heptonstall, M. Heurs, S. Hild, D. Hoak, D. Hofman,
K. Holt, D. E. Holz, P. Hopkins, J. Hough, E. A. Houston, E. J. Howell, Y. M.
Hu, S. Huang, E. A. Huerta, D. Huet, B. Hughey, S. H. Huttner, T. Huynh-Dinh,
N. Indik, D. R. Ingram, R. Inta, H. N. Isa, J.-M. Isac, M. Isi, T. Isogai, B.
R. Iyer, K. Izumi, T. Jacqmin, H. Jang, K. Jani, P. Jaranowski, S. Jawahar,
L. Jian, F. Jim'enez-Forteza, W. W. Johnson, D. I. Jones, R. Jones, R. J. G.
Jonker, L. Ju, Haris K, C. V. Kalaghatgi, V. Kalogera, S. Kandhasamy, G.
Kang, J. B. Kanner, S. J. Kapadia, S. Karki, K. S. Karvinen, M. Kasprzack, E.
Katsavounidis, W. Katzman, S. Kaufer, T. Kaur, K. Kawabe, F. K'ef'elian, M.
S. Kehl, D. Keitel, D. B. Kelley, W. Kells, R. Kennedy, J. S. Key, F. Y.
Khalili, I. Khan, Z. Khan, E. A. Khazanov, N. Kijbunchoo, Chi-Woong Kim,
Chunglee Kim, J. Kim, K. Kim, N. Kim, W. Kim, Y.-M. Kim, S. J. Kimbrell, E.
J. King, P. J. King, J. S. Kissel, B. Klein, L. Kleybolte, S. Klimenko, S. M.
Koehlenbeck, S. Koley, V. Kondrashov, A. Kontos, M. Korobko, W. Z. Korth, I.
Kowalska, D. B. Kozak, V. Kringel, B. Krishnan, A. Kr'olak, C. Krueger, G.
Kuehn, P. Kumar, R. Kumar, L. Kuo, A. Kutynia, B. D. Lackey, M. Landry, J.
Lange, B. Lantz, P. D. Lasky, M. Laxen, A. Lazzarini, C. Lazzaro, P. Leaci,
S. Leavey, E. O. Lebigot, C. H. Lee, H. K. Lee, H. M. Lee, K. Lee, A. Lenon,
M. Leonardi, J. R. Leong, N. Leroy, N. Letendre, Y. Levin, J. B. Lewis, T. G.
F. Li, A. Libson, T. B. Littenberg, N. A. Lockerbie, A. L. Lombardi, J. E.
Lord, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. D. Lough, H.
L"uck, A. P. Lundgren, R. Lynch, Y. Ma, B. Machenschalk, M. MacInnis, D. M.
Macleod, F. Maga\~na-Sandoval, L. Maga\~na Zertuche, R. M. Magee, E.
Majorana, I. Maksimovic, V. Malvezzi, N. Man, V. Mandic, V. Mangano, G. L.
Mansell, M. Manske, M. Mantovani, F. Marchesoni, F. Marion, S. M'arka, Z.
M'arka, A. S. Markosyan, E. Maros, F. Martelli, L. Martellini, I. W. Martin,
D. V. Martynov, J. N. Marx, K. Mason, A. Masserot, T. J. Massinger, M.
Masso-Reid, S. Mastrogiovanni, F. Matichard, L. Matone, N. Mavalvala, N.
Mazumder, R. McCarthy, D. E. McClelland, S. McCormick, S. C. McGuire, G.
McIntyre, J. McIver, D. J. McManus, T. McRae, S. T. McWilliams, D. Meacher,
G. D. Meadors, J. Meidam, A. Melatos, G. Mendell, R. A. Mercer, E. L. Merilh,
M. Merzougui, S. Meshkov, C. Messenger, C. Messick, R. Metzdorff, P. M.
Meyers, F. Mezzani, H. Miao, C. Michel, H. Middleton, E. E. Mikhailov, L.
Milano, A. L. Miller, A. Miller, B. B. Miller, J. Miller, M. Millhouse, Y.
Minenkov, J. Ming, S. Mirshekari, C. Mishra, S. Mitra, V. P. Mitrofanov, G.
Mitselmakher, R. Mittleman, A. Moggi, M. Mohan, S. R. P. Mohapatra, M.
Montani, B. C. Moore, C. J. Moore, D. Moraru, G. Moreno, S. R. Morriss, K.
Mossavi, B. Mours, C. M. Mow-Lowry, G. Mueller, A. W. Muir, Arunava
Mukherjee, D. Mukherjee, S. Mukherjee, N. Mukund, A. Mullavey, J. Munch, D.
J. Murphy, P. G. Murray, A. Mytidis, I. Nardecchia, L. Naticchioni, R. K.
Nayak, K. Nedkova, G. Nelemans, T. J. N. Nelson, M. Neri, A. Neunzert, G.
Newton, T. T. Nguyen, A. B. Nielsen, S. Nissanke, A. Nitz, F. Nocera, D.
Nolting, M. E. N. Normandin, L. K. Nuttall, J. Oberling, E. Ochsner, J.
O'Dell, E. Oelker, G. H. Ogin, J. J. Oh, S. H. Oh, F. Ohme, M. Oliver, P.
Oppermann, Richard J. Oram, B. O'Reilly, R. O'Shaughnessy, D. J. Ottaway, H.
Overmier, B. J. Owen, A. Pai, S. A. Pai, J. R. Palamos, O. Palashov, C.
Palomba, A. Pal-Singh, H. Pan, C. Pankow, B. C. Pant, F. Paoletti, A. Paoli,
M. A. Papa, H. R. Paris, W. Parker, D. Pascucci, A. Pasqualetti, R.
Passaquieti, D. Passuello, B. Patricelli, Z. Patrick, B. L. Pearlstone, M.
Pedraza, R. Pedurand, L. Pekowsky, A. Pele, S. Penn, A. Perreca, L. M. Perri,
M. Phelps, O. J. Piccinni, M. Pichot, F. Piergiovanni, V. Pierro, G. Pillant,
L. Pinard, I. M. Pinto, M. Pitkin, M. Poe, R. Poggiani, P. Popolizio, A.
Post, J. Powell, J. Prasad, V. Predoi, T. Prestegard, L. R. Price, M.
Prijatelj, M. Principe, S. Privitera, R. Prix, G. A. Prodi, L. Prokhorov, O.
Puncken, M. Punturo, P. Puppo, M. P"urrer, H. Qi, J. Qin, S. Qiu, V.
Quetschke, E. A. Quintero, R. Quitzow-James, F. J. Raab, D. S. Rabeling, H.
Radkins, P. Raffai, S. Raja, C. Rajan, M. Rakhmanov, P. Rapagnani, V.
Raymond, M. Razzano, V. Re, J. Read, C. M. Reed, T. Regimbau, L. Rei, S.
Reid, D. H. Reitze, H. Rew, S. D. Reyes, F. Ricci, K. Riles, M. Rizzo, N. A.
Robertson, R. Robie, F. Robinet, A. Rocchi, L. Rolland, J. G. Rollins, V. J.
Roma, J. D. Romano, R. Romano, G. Romanov, J. H. Romie, D. Rosi'nska, S.
Rowan, A. R"udiger, P. Ruggi, K. Ryan, S. Sachdev, T. Sadecki, L. Sadeghian,
M. Sakellariadou, L. Salconi, M. Saleem, F. Salemi, A. Samajdar, L. Sammut,
E. J. Sanchez, V. Sandberg, B. Sandeen, J. R. Sanders, B. Sassolas, B. S.
Sathyaprakash, P. R. Saulson, O. E. S. Sauter, R. L. Savage, A. Sawadsky, P.
Schale, R. Schilling, J. Schmidt, P. Schmidt, R. Schnabel, R. M. S.
Schofield, A. Sch"onbeck, E. Schreiber, D. Schuette, B. F. Schutz, J. Scott,
S. M. Scott, D. Sellers, A. S. Sengupta, D. Sentenac, V. Sequino, A. Sergeev,
Y. Setyawati, D. A. Shaddock, T. Shaffer, M. S. Shahriar, M. Shaltev, B.
Shapiro, P. Shawhan, A. Sheperd, D. H. Shoemaker, K. Siellez, X. Siemens, M.
Sieniawska, D. Sigg, A. D. Silva, A. Singer, L. P. Singer, A. Singh, R.
Singh, A. Singhal, A. M. Sintes, B. J. J. Slagmolen, J. R. Smith, N. D.
Smith, R. J. E. Smith, E. J. Son, B. Sorazu, F. Sorrentino, T. Souradeep, A.
K. Srivastava, A. Staley, M. Steinke, J. Steinlechner, S. Steinlechner, D.
Steinmeyer, B. C. Stephens, R. Stone, K. A. Strain, N. Straniero, G. Stratta,
N. A. Strauss, S. Strigin, R. Sturani, A. L. Stuver, T. Z. Summerscales, L.
Sun, S. Sunil, P. J. Sutton, B. L. Swinkels, M. J. Szczepa'nczyk, M. Tacca,
D. Talukder, D. B. Tanner, M. T'apai, S. P. Tarabrin, A. Taracchini, R.
Taylor, T. Theeg, M. P. Thirugnanasambandam, E. G. Thomas, M. Thomas, P.
Thomas, K. A. Thorne, E. Thrane, S. Tiwari, V. Tiwari, K. V. Tokmakov, K.
Toland, C. Tomlinson, M. Tonelli, Z. Tornasi, C. V. Torres, C. I. Torrie, D.
T"oyr"a, F. Travasso, G. Traylor, D. Trifir`o, M. C. Tringali, L. Trozzo, M.
Tse, M. Turconi, D. Tuyenbayev, D. Ugolini, C. S. Unnikrishnan, A. L. Urban,
S. A. Usman, H. Vahlbruch, G. Vajente, G. Valdes, N. van Bakel, M. van
Beuzekom, J. F. J. van den Brand, C. Van Den Broeck, D. C. Vander-Hyde, L.
van der Schaaf, J. V. van Heijningen, A. A. van Veggel, M. Vardaro, S. Vass,
M. Vas'uth, R. Vaulin, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, K.
Venkateswara, D. Verkindt, F. Vetrano, A. Vicer'e, S. Vinciguerra, D. J.
Vine, J.-Y. Vinet, S. Vitale, T. Vo, H. Vocca, C. Vorvick, D. V. Voss, W. D.
Vousden, S. P. Vyatchanin, A. R. Wade, L. E. Wade, M. Wade, M. Walker, L.
Wallace, S. Walsh, G. Wang, H. Wang, M. Wang, X. Wang, Y. Wang, R. L. Ward,
J. Warner, M. Was, B. Weaver, L.-W. Wei, M. Weinert, A. J. Weinstein, R.
Weiss, L. Wen, P. Wessels, T. Westphal, K. Wette, J. T. Whelan, B. F.
Whiting, 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. Worden, J.
L. Wright, D. S. Wu, G. Wu, J. Yablon, W. Yam, H. Yamamoto, C. C. Yancey, H.
Yu, M. Yvert, A. Zadro.zny, L. Zangrando, M. Zanolin, J.-P. Zendri, M. Zevin,
L. Zhang, M. Zhang, Y. Zhang, C. Zhao, M. Zhou, Z. Zhou, X. J. Zhu, M. E.
Zucker, S. E. Zuraw, J. Zweizig, M. Boyle, M. Campanelli, T. Chu, M. Clark,
E. Fauchon-Jones, H. Fong, M. Hannam, J. Healy, D. Hemberger, I. Hinder, S.
Husa, C. Kalaghati, S. Khan, L.E. Kidder, M. Kinsey, P. Laguna, L. T. London,
C. O. Lousto, G. Lovelace, S. Ossokine, F. Pannarale, H. P. Pfeiffer, M.
Scheel, D. M. Shoemaker, B. Szilagyi, S. Teukolsky, A. Vano Vinuales, Y.
Zlochower | Directly comparing GW150914 with numerical solutions of Einstein's
equations for binary black hole coalescence | 29 pages. Full version of tables available electronically with this
submission | Phys. Rev. D 94, 064035 (2016) | 10.1103/PhysRevD.94.064035 | LIGO P1500263 | gr-qc astro-ph.CO astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compare GW150914 directly to simulations of coalescing binary black holes
in full general relativity, accounting for all the spin-weighted quadrupolar
modes, and separately accounting for all the quadrupolar and octopolar modes.
Consistent with the posterior distributions reported in LVC_PE[1] (at 90%
confidence), we find the data are compatible with a wide range of nonprecessing
and precessing simulations. Followup simulations performed using
previously-estimated binary parameters most resemble the data. Comparisons
including only the quadrupolar modes constrain the total redshifted mass Mz \in
[64 - 82M_\odot], mass ratio q = m2/m1 \in [0.6,1], and effective aligned spin
\chi_eff \in [-0.3, 0.2], where \chi_{eff} = (S1/m1 + S2/m2) \cdot\hat{L} /M.
Including both quadrupolar and octopolar modes, we find the mass ratio is even
more tightly constrained. Simulations with extreme mass ratios and effective
spins are highly inconsistent with the data, at any mass. Several nonprecessing
and precessing simulations with similar mass ratio and \chi_{eff} are
consistent with the data. Though correlated, the components' spins (both in
magnitude and directions) are not significantly constrained by the data. For
nonprecessing binaries, interpolating between simulations, we reconstruct a
posterior distribution consistent with previous results. The final black hole's
redshifted mass is consistent with Mf,z between 64.0 - 73.5M_\odot and the
final black hole's dimensionless spin parameter is consistent with af = 0.62 -
0.73. As our approach invokes no intermediate approximations to general
relativity and can strongly reject binaries whose radiation is inconsistent
with the data, our analysis provides a valuable complement to LVC_PE[1].
| [
{
"created": "Fri, 3 Jun 2016 20:13:19 GMT",
"version": "v1"
}
] | 2016-09-21 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"Abbott",
"B. P.",
""
],
[
"Abbott",
"R.",
""
],
[
"Abbott",
"T. D.",
""
],
[
"Abernathy",
"M. R.",
""
],
[
"Acernese",
"F... | We compare GW150914 directly to simulations of coalescing binary black holes in full general relativity, accounting for all the spin-weighted quadrupolar modes, and separately accounting for all the quadrupolar and octopolar modes. Consistent with the posterior distributions reported in LVC_PE[1] (at 90% confidence), we find the data are compatible with a wide range of nonprecessing and precessing simulations. Followup simulations performed using previously-estimated binary parameters most resemble the data. Comparisons including only the quadrupolar modes constrain the total redshifted mass Mz \in [64 - 82M_\odot], mass ratio q = m2/m1 \in [0.6,1], and effective aligned spin \chi_eff \in [-0.3, 0.2], where \chi_{eff} = (S1/m1 + S2/m2) \cdot\hat{L} /M. Including both quadrupolar and octopolar modes, we find the mass ratio is even more tightly constrained. Simulations with extreme mass ratios and effective spins are highly inconsistent with the data, at any mass. Several nonprecessing and precessing simulations with similar mass ratio and \chi_{eff} are consistent with the data. Though correlated, the components' spins (both in magnitude and directions) are not significantly constrained by the data. For nonprecessing binaries, interpolating between simulations, we reconstruct a posterior distribution consistent with previous results. The final black hole's redshifted mass is consistent with Mf,z between 64.0 - 73.5M_\odot and the final black hole's dimensionless spin parameter is consistent with af = 0.62 - 0.73. As our approach invokes no intermediate approximations to general relativity and can strongly reject binaries whose radiation is inconsistent with the data, our analysis provides a valuable complement to LVC_PE[1]. |
gr-qc/0611139 | Ramin G. Daghigh | R. G. Daghigh, G. Kunstatter, and J. Ziprick | The Mystery of the Asymptotic Quasinormal Modes of Gauss-Bonnet Black
Holes | 12 pages and 5 figures | Class.Quant.Grav.24:1981-1992,2007 | 10.1088/0264-9381/24/8/005 | null | gr-qc | null | We analyze the quasinormal modes of $D$-dimensional Schwarzschild black holes
with the Gauss-Bonnet correction in the large damping limit and show that
standard analytic techniques cannot be applied in a straightforward manner to
the case of infinite damping. However, by using a combination of analytic and
numeric techniques we are able to calculate the quasinormal mode frequencies in
a range where the damping is large but finite. We show that for this damping
region the famous $\ln(3)$ appears in the real part of the quasinormal mode
frequency. In our calculations, the Gauss-Bonnet coupling, $\alpha$, is taken
to be much smaller than the parameter $\mu$, which is related to the black hole
mass.
| [
{
"created": "Mon, 27 Nov 2006 00:04:51 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Daghigh",
"R. G.",
""
],
[
"Kunstatter",
"G.",
""
],
[
"Ziprick",
"J.",
""
]
] | We analyze the quasinormal modes of $D$-dimensional Schwarzschild black holes with the Gauss-Bonnet correction in the large damping limit and show that standard analytic techniques cannot be applied in a straightforward manner to the case of infinite damping. However, by using a combination of analytic and numeric techniques we are able to calculate the quasinormal mode frequencies in a range where the damping is large but finite. We show that for this damping region the famous $\ln(3)$ appears in the real part of the quasinormal mode frequency. In our calculations, the Gauss-Bonnet coupling, $\alpha$, is taken to be much smaller than the parameter $\mu$, which is related to the black hole mass. |
2002.08835 | Juan Rincon | Juan David Rincon-Estrada and David Bermudez | Instabilities in an optical black-hole laser | 14 pages, 12 figures, 42 references | null | 10.1002/andp.202000239 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Hamiltonian of optical fields in a nonlinear dispersive fiber is studied.
Quantum field fluctuations are spontaneously created close to an optical event
horizon through the analog Hawking effect. The simplest model is considered for
an optical black-hole laser, where the Hawking radiation is produced and
amplified inside a cavity formed by two horizons: a black hole and a white
hole. It is found that resonant Hawking radiation originates from a discrete
set of instabilities and tunnels out of the horizons. Finally, the numerical
results are compared with the resonance and instability conditions and a
phenomenological model is developed to give a clear physical picture.
| [
{
"created": "Thu, 20 Feb 2020 16:19:16 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Nov 2020 13:43:18 GMT",
"version": "v2"
}
] | 2021-02-03 | [
[
"Rincon-Estrada",
"Juan David",
""
],
[
"Bermudez",
"David",
""
]
] | The Hamiltonian of optical fields in a nonlinear dispersive fiber is studied. Quantum field fluctuations are spontaneously created close to an optical event horizon through the analog Hawking effect. The simplest model is considered for an optical black-hole laser, where the Hawking radiation is produced and amplified inside a cavity formed by two horizons: a black hole and a white hole. It is found that resonant Hawking radiation originates from a discrete set of instabilities and tunnels out of the horizons. Finally, the numerical results are compared with the resonance and instability conditions and a phenomenological model is developed to give a clear physical picture. |
2408.02717 | Piyali Bhar | Piyali Bhar | Properties of wormhole model in de Rham-Gabadadze-Tolley like massive
gravity with specific matter density | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In the conventional method of studying wormhole (WH) geometry, traversability
requires the presence of exotic matter, which also provides negative gravity
effects to keep the wormhole throat open. In dRGT massive gravity theory, we
produce two types of WH solutions in our present paper. Selecting a static and
spherically symmetric metric for the background geometry, we obtain the field
equations for exact WH solutions. We derive the WH geometry completely for the
two different choices of redshift functions. All the energy conditions
including the NEC are violated by the obtained WH solutions. Various plots are
used to illustrate the behavior of the wormhole for a suitable range of
$m^2c_1$, where $m$ is the graviton mass. It is observed that the photon
deflection angle becomes negative for all values of $m^2c_1$ as a result of the
repulsive action of gravity. It is also studied that the repulsive impact of
massive gravitons pushes the spacetime geometry so strongly that the asymptotic
flatness is affected. The Volume Integral Quantifier (VIQ) has also been
computed to determine the amounts of matter that violate the null energy
condition. The complexity factor of the proposed model is also discussed.
| [
{
"created": "Mon, 5 Aug 2024 16:40:41 GMT",
"version": "v1"
}
] | 2024-08-07 | [
[
"Bhar",
"Piyali",
""
]
] | In the conventional method of studying wormhole (WH) geometry, traversability requires the presence of exotic matter, which also provides negative gravity effects to keep the wormhole throat open. In dRGT massive gravity theory, we produce two types of WH solutions in our present paper. Selecting a static and spherically symmetric metric for the background geometry, we obtain the field equations for exact WH solutions. We derive the WH geometry completely for the two different choices of redshift functions. All the energy conditions including the NEC are violated by the obtained WH solutions. Various plots are used to illustrate the behavior of the wormhole for a suitable range of $m^2c_1$, where $m$ is the graviton mass. It is observed that the photon deflection angle becomes negative for all values of $m^2c_1$ as a result of the repulsive action of gravity. It is also studied that the repulsive impact of massive gravitons pushes the spacetime geometry so strongly that the asymptotic flatness is affected. The Volume Integral Quantifier (VIQ) has also been computed to determine the amounts of matter that violate the null energy condition. The complexity factor of the proposed model is also discussed. |
gr-qc/9803073 | Joanne D. Cohn | J.D. Cohn and D.I. Kaiser | Where do all the supercurvature modes go? | 23 pages, 3 .eps figures included, uses prd,aps, epsfig style files
final version to appear in Phys Rev D, expanded concluding section | Phys.Rev. D58 (1998) 083515 | 10.1103/PhysRevD.58.083515 | UIUC-THC/98-2, HUTP-98/A010 | gr-qc astro-ph | null | In the hyperbolic slicing of de Sitter space appropriate for open universe
models, a curvature scale is present and supercurvature fluctuations are
possible. In some cases, the expansion of a scalar field in the Bunch-Davies
vacuum includes supercurvature modes, as shown by Sasaki, Tanaka and Yamamoto.
We express the normalizable vacuum supercurvature modes for a massless scalar
field in terms of the basis modes for the spatially-flat slicing of de Sitter
space.
| [
{
"created": "Sat, 21 Mar 1998 21:05:17 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Jul 1998 19:29:21 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Cohn",
"J. D.",
""
],
[
"Kaiser",
"D. I.",
""
]
] | In the hyperbolic slicing of de Sitter space appropriate for open universe models, a curvature scale is present and supercurvature fluctuations are possible. In some cases, the expansion of a scalar field in the Bunch-Davies vacuum includes supercurvature modes, as shown by Sasaki, Tanaka and Yamamoto. We express the normalizable vacuum supercurvature modes for a massless scalar field in terms of the basis modes for the spatially-flat slicing of de Sitter space. |
2312.11586 | Ioannis Contopoulos | Ioannis Contopoulos, Demosthenes Kazanas, Demetrios B. Papadopoulos | Gravitational Waves from the Pulsar Magnetosphere | 9 pages, 1 figure, accepted for publication in Monthly Notices | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/publicdomain/zero/1.0/ | We investigate the generation of gravitational waves from the rotation of an
orthogonal pulsar magnetosphere in flat space time. We calculate the first
order metric perturbation due to the rotation of the non-axisymmetric
distribution of electromagnetic energy density around the central star. We show
that gravitational waves from a strong magnetic field pulsar right after its
formation within a distance of 1 kpc may be detectable with the new generation
of gravitational wave detectors.
| [
{
"created": "Mon, 18 Dec 2023 14:29:33 GMT",
"version": "v1"
}
] | 2023-12-20 | [
[
"Contopoulos",
"Ioannis",
""
],
[
"Kazanas",
"Demosthenes",
""
],
[
"Papadopoulos",
"Demetrios B.",
""
]
] | We investigate the generation of gravitational waves from the rotation of an orthogonal pulsar magnetosphere in flat space time. We calculate the first order metric perturbation due to the rotation of the non-axisymmetric distribution of electromagnetic energy density around the central star. We show that gravitational waves from a strong magnetic field pulsar right after its formation within a distance of 1 kpc may be detectable with the new generation of gravitational wave detectors. |
1002.2217 | Steven L. Liebling | Steven L. Liebling | Dynamics of Rotating, Magnetized Neutron Stars | 3 pages, 2 figures; Proceedings of the 12th Marcel Grossman Meeting,
Paris, July 12-18, 2009 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using a fully general relativistic implementation of ideal
magnetohydrodynamics with no assumed symmetries in three spatial dimensions,
the dynamics of magnetized, rigidly rotating neutron stars are studied.
Beginning with fully consistent initial data constructed with Magstar, part of
the Lorene project, we study the dynamics and stability of rotating, magnetized
polytropic stars as models of neutron stars. Evolutions suggest that some of
these rotating, magnetized stars may be minimally unstable occurring at the
threshold of black hole formation.
| [
{
"created": "Wed, 10 Feb 2010 21:01:09 GMT",
"version": "v1"
}
] | 2010-02-12 | [
[
"Liebling",
"Steven L.",
""
]
] | Using a fully general relativistic implementation of ideal magnetohydrodynamics with no assumed symmetries in three spatial dimensions, the dynamics of magnetized, rigidly rotating neutron stars are studied. Beginning with fully consistent initial data constructed with Magstar, part of the Lorene project, we study the dynamics and stability of rotating, magnetized polytropic stars as models of neutron stars. Evolutions suggest that some of these rotating, magnetized stars may be minimally unstable occurring at the threshold of black hole formation. |
0706.2541 | Pablo Laguna | Frank Herrmann, Ian Hinder, Deirdre M. Shoemaker, Pablo Laguna and
Richard A. Matzner | Binary Black Holes: Spin Dynamics and Gravitational Recoil | 15 pages, 10 figures, replaced with version accepted for publication
in PRD | Phys.Rev.D76:084032,2007 | 10.1103/PhysRevD.76.084032 | null | gr-qc astro-ph | null | We present a study of spinning black hole binaries focusing on the spin
dynamics of the individual black holes as well as on the gravitational recoil
acquired by the black hole produced by the merger. We consider two series of
initial spin orientations away from the binary orbital plane. In one of the
series, the spins are anti-aligned; for the second series, one of the spins
points away from the binary along the line separating the black holes. We find
a remarkable agreement between the spin dynamics predicted at 2nd
post-Newtonian order and those from numerical relativity. For each
configuration, we compute the kick of the final black hole. We use the kick
estimates from the series with anti-aligned spins to fit the parameters in the
\KKF{,} and verify that the recoil along the direction of the orbital angular
momentum is $\propto \sin\theta$ and on the orbital plane $\propto \cos\theta$,
with $\theta$ the angle between the spin directions and the orbital angular
momentum. We also find that the black hole spins can be well estimated by
evaluating the isolated horizon spin on spheres of constant coordinate radius.
| [
{
"created": "Mon, 18 Jun 2007 17:47:38 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Sep 2007 17:27:37 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Herrmann",
"Frank",
""
],
[
"Hinder",
"Ian",
""
],
[
"Shoemaker",
"Deirdre M.",
""
],
[
"Laguna",
"Pablo",
""
],
[
"Matzner",
"Richard A.",
""
]
] | We present a study of spinning black hole binaries focusing on the spin dynamics of the individual black holes as well as on the gravitational recoil acquired by the black hole produced by the merger. We consider two series of initial spin orientations away from the binary orbital plane. In one of the series, the spins are anti-aligned; for the second series, one of the spins points away from the binary along the line separating the black holes. We find a remarkable agreement between the spin dynamics predicted at 2nd post-Newtonian order and those from numerical relativity. For each configuration, we compute the kick of the final black hole. We use the kick estimates from the series with anti-aligned spins to fit the parameters in the \KKF{,} and verify that the recoil along the direction of the orbital angular momentum is $\propto \sin\theta$ and on the orbital plane $\propto \cos\theta$, with $\theta$ the angle between the spin directions and the orbital angular momentum. We also find that the black hole spins can be well estimated by evaluating the isolated horizon spin on spheres of constant coordinate radius. |
2002.01302 | Seyed Hossein Hendi Dr. | S. H. Hendi, A. M. Tavakkoli, S. Panahiyan, B. Eslam Panah, E.
Hackmann | Simulation of geodesic trajectory of charged BTZ black holes in massive
gravity | 26 pages with 15 captioned figures | null | 10.1140/epjc/s10052-020-8065-9 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In order to classify and understand the spacetime structure, investigation of
the geodesic motion of massive and massless particles is a key tool. So the
geodesic equation is a central equation of gravitating systems and the subject
of geodesics in the black hole dictionary attracted much attention. In this
paper, we give a full description of geodesic motions in three-dimensional
spacetime. We investigate the geodesics near charged BTZ black holes and then
generalize our prescriptions to the case of massive gravity. We show that
electric charge is a critical parameter for categorizing the geodesic motions
of both lightlike and timelike particles. In addition, we classify the type of
geodesics based on the particle properties and geometry of spacetime.
| [
{
"created": "Sat, 1 Feb 2020 20:44:00 GMT",
"version": "v1"
}
] | 2020-07-15 | [
[
"Hendi",
"S. H.",
""
],
[
"Tavakkoli",
"A. M.",
""
],
[
"Panahiyan",
"S.",
""
],
[
"Panah",
"B. Eslam",
""
],
[
"Hackmann",
"E.",
""
]
] | In order to classify and understand the spacetime structure, investigation of the geodesic motion of massive and massless particles is a key tool. So the geodesic equation is a central equation of gravitating systems and the subject of geodesics in the black hole dictionary attracted much attention. In this paper, we give a full description of geodesic motions in three-dimensional spacetime. We investigate the geodesics near charged BTZ black holes and then generalize our prescriptions to the case of massive gravity. We show that electric charge is a critical parameter for categorizing the geodesic motions of both lightlike and timelike particles. In addition, we classify the type of geodesics based on the particle properties and geometry of spacetime. |
1708.09576 | Sijie Gao | Jincheng An and Sijie Gao | Five-dimensional Myers-Perry Black Holes as Particle Accelerators | 17 pages, no figure | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been shown that black holes could be used as particle accelerators to
create arbitrarily high center-of-mass (CM) energy if certain critical
conditions are satisfied. Most studies so far are confined in four-dimensional
spacetimes. In this paper, we present a systematic analysis on five-dimensional
Myers-Perry black holes and find some novel properties compared to
four-dimensional Kerr black holes. Firstly, we give a rigorous proof that
untrhigh energy collisions cannot occur near a five-dimensional nonextremal
black hole. Secondly, For extremal black holes, we find a critical condition on
the particles' parameters causing ultraenergetic collisions. Thirdly, when the
spacetime contains a naked singularity, we show that the CM energy could
diverge at the singularity if one of the particle just bounces back at the
singularity. Finally, we explore a special and important case where the naked
singularity just begins to form. Surprisingly, the ultraenergetic collisions do
not need any fine-turning in that case. However, we find that one of the
conserved angular momentums must be nonzero.
| [
{
"created": "Thu, 31 Aug 2017 06:15:17 GMT",
"version": "v1"
}
] | 2017-09-01 | [
[
"An",
"Jincheng",
""
],
[
"Gao",
"Sijie",
""
]
] | It has been shown that black holes could be used as particle accelerators to create arbitrarily high center-of-mass (CM) energy if certain critical conditions are satisfied. Most studies so far are confined in four-dimensional spacetimes. In this paper, we present a systematic analysis on five-dimensional Myers-Perry black holes and find some novel properties compared to four-dimensional Kerr black holes. Firstly, we give a rigorous proof that untrhigh energy collisions cannot occur near a five-dimensional nonextremal black hole. Secondly, For extremal black holes, we find a critical condition on the particles' parameters causing ultraenergetic collisions. Thirdly, when the spacetime contains a naked singularity, we show that the CM energy could diverge at the singularity if one of the particle just bounces back at the singularity. Finally, we explore a special and important case where the naked singularity just begins to form. Surprisingly, the ultraenergetic collisions do not need any fine-turning in that case. However, we find that one of the conserved angular momentums must be nonzero. |
1009.3572 | Farook Rahaman | F. Rahaman, K. K. Nandi, A. Bhadra, M. Kalam and K. Chakraborty | Perfect Fluid Dark Matter | 7 pages, 5 figures, To appear in Phys. Lett. B (2010) | Phys.Lett.B694:10-15,2010 | 10.1016/j.physletb.2010.09.038 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Taking the flat rotation curve as input and treating the matter content in
the galactic halo region as perfect fluid, we obtain space time metric at the
galactic halo region in the framework of general relativity. We find that the
resultant metric is a non-relativistic-dark-matter-induced space-time embedded
in a static Friedmann-Lema\^itre-Robertson-Walker universe. This means that the
flat rotation curve not only leads to the existence of dark matter but also
suggests the background geometry of the universe. The flat rotation curve and
the demand that the dark matter be non-exotic together indicate a (nearly) flat
universe as favored by the modern cosmological observations. We obtain the
expressions for energy density and pressure of dark matter halo and
consequently the equation of state of dark matter. Various other aspects of the
solution are also analyzed.
| [
{
"created": "Sat, 18 Sep 2010 17:34:44 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Sep 2010 10:42:01 GMT",
"version": "v2"
}
] | 2010-11-26 | [
[
"Rahaman",
"F.",
""
],
[
"Nandi",
"K. K.",
""
],
[
"Bhadra",
"A.",
""
],
[
"Kalam",
"M.",
""
],
[
"Chakraborty",
"K.",
""
]
] | Taking the flat rotation curve as input and treating the matter content in the galactic halo region as perfect fluid, we obtain space time metric at the galactic halo region in the framework of general relativity. We find that the resultant metric is a non-relativistic-dark-matter-induced space-time embedded in a static Friedmann-Lema\^itre-Robertson-Walker universe. This means that the flat rotation curve not only leads to the existence of dark matter but also suggests the background geometry of the universe. The flat rotation curve and the demand that the dark matter be non-exotic together indicate a (nearly) flat universe as favored by the modern cosmological observations. We obtain the expressions for energy density and pressure of dark matter halo and consequently the equation of state of dark matter. Various other aspects of the solution are also analyzed. |
1510.04457 | Uro\v{s} Kosti\'c | Uro\v{s} Kosti\'c, Martin Horvat, Andreja Gomboc | Relativistic Positioning System in Perturbed Space-time | 25 pages | Class. Quantum Grav. 32 (2015) 215004 | 10.1088/0264-9381/32/21/215004 | null | gr-qc physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a variant of a Global Navigation Satellite System called a
Relativistic Positioning System (RPS), which is based on emission coordinates.
We modelled the RPS dynamics in a space-time around Earth, described by a
perturbed Schwarzschild metric, where we included the perturbations due to
Earth multipoles (up to the 6th), the Moon, the Sun, Venus, Jupiter, solid
tide, ocean tide, and Kerr rotation effect. The exchange of signals between the
satellites and a user was calculated using a ray-tracing method in the
Schwarzschild space-time. We find that positioning in a perturbed space-time is
feasible and is highly accurate already with standard numerical procedures: the
positioning algorithms used to transform between the emission and the
Schwarzschild coordinates of the user are very accurate and time efficient --
on a laptop it takes 0.04 s to determine the user's spatial and time
coordinates with a relative accuracy of $10^{-28}-10^{-26}$ and
$10^{-32}-10^{-30}$, respectively.
| [
{
"created": "Thu, 15 Oct 2015 09:35:25 GMT",
"version": "v1"
}
] | 2015-10-21 | [
[
"Kostić",
"Uroš",
""
],
[
"Horvat",
"Martin",
""
],
[
"Gomboc",
"Andreja",
""
]
] | We present a variant of a Global Navigation Satellite System called a Relativistic Positioning System (RPS), which is based on emission coordinates. We modelled the RPS dynamics in a space-time around Earth, described by a perturbed Schwarzschild metric, where we included the perturbations due to Earth multipoles (up to the 6th), the Moon, the Sun, Venus, Jupiter, solid tide, ocean tide, and Kerr rotation effect. The exchange of signals between the satellites and a user was calculated using a ray-tracing method in the Schwarzschild space-time. We find that positioning in a perturbed space-time is feasible and is highly accurate already with standard numerical procedures: the positioning algorithms used to transform between the emission and the Schwarzschild coordinates of the user are very accurate and time efficient -- on a laptop it takes 0.04 s to determine the user's spatial and time coordinates with a relative accuracy of $10^{-28}-10^{-26}$ and $10^{-32}-10^{-30}$, respectively. |
gr-qc/0411135 | Nathalie Deruelle | Nathalie Deruelle and Yoshiyuki Morisawa | Mass and angular momenta of Kerr anti-de Sitter spacetimes in
Einstein-Gauss-Bonnet theory | null | Class.Quant.Grav. 22 (2005) 933-938 | 10.1088/0264-9381/22/6/002 | null | gr-qc hep-th | null | We compute the mass and angular momenta of rotating anti-de Sitter spacetimes
in Einstein-Gauss-Bonnet theory of gravity using a superpotential derived from
standard Noether identities. The calculation relies on the fact that the
Einstein and Einstein-Gauss-Bonnet vacuum equations are the same when
linearized on maximally symmetric backgrounds and uses the recently discovered
D-dimensional Kerr-anti-de Sitter solutions to Einstein's equations.
| [
{
"created": "Mon, 29 Nov 2004 07:19:24 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Deruelle",
"Nathalie",
""
],
[
"Morisawa",
"Yoshiyuki",
""
]
] | We compute the mass and angular momenta of rotating anti-de Sitter spacetimes in Einstein-Gauss-Bonnet theory of gravity using a superpotential derived from standard Noether identities. The calculation relies on the fact that the Einstein and Einstein-Gauss-Bonnet vacuum equations are the same when linearized on maximally symmetric backgrounds and uses the recently discovered D-dimensional Kerr-anti-de Sitter solutions to Einstein's equations. |
gr-qc/9512017 | Kiyoshi Ezawa | Kiyoshi Ezawa | A semiclassical interpretation of the topological solutions for
canonical quantum gravity | 30 pages Latex (one figure available as a postscript file) | Phys.Rev.D53:5651-5663,1996 | 10.1103/PhysRevD.53.5651 | OU-HET/231 | gr-qc | null | Ashtekar's formulation for canonical quantum gravity is known to possess the
topological solutions which have their supports only on the moduli space $\CN$
of flat $SL(2,C)$ connections. We show that each point on the moduli space
$\CN$ corresponds to a geometric structure, or more precisely the Lorentz group
part of a family of Lorentzian structures, on the flat (3+1)-dimensional
spacetime. A detailed analysis is given in the case where the spacetime is
homeomorphic to $R\times T^{3}$. Most of the points on the moduli space $\CN$
yield pathological spacetimes which suffers from singularities on each spatial
hypersurface or which violates the strong causality condition. There is,
however, a subspace of $\CN$ on which each point corresponds to a family of
regular spacetimes.
| [
{
"created": "Fri, 8 Dec 1995 11:04:23 GMT",
"version": "v1"
}
] | 2011-09-09 | [
[
"Ezawa",
"Kiyoshi",
""
]
] | Ashtekar's formulation for canonical quantum gravity is known to possess the topological solutions which have their supports only on the moduli space $\CN$ of flat $SL(2,C)$ connections. We show that each point on the moduli space $\CN$ corresponds to a geometric structure, or more precisely the Lorentz group part of a family of Lorentzian structures, on the flat (3+1)-dimensional spacetime. A detailed analysis is given in the case where the spacetime is homeomorphic to $R\times T^{3}$. Most of the points on the moduli space $\CN$ yield pathological spacetimes which suffers from singularities on each spatial hypersurface or which violates the strong causality condition. There is, however, a subspace of $\CN$ on which each point corresponds to a family of regular spacetimes. |
1005.4169 | Soon-Tae Hong | Soon-Tae Hong, Sung-Won Kim | Hydrodynamics and global embeddings of Taub-NUT spacetime | 6 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | On Taub-NUT spacetime, we investigate hydrodynamic properties of perfect
fluid spiraling inward toward the spacetime along a conical surface. On the
equatorial plane of the Taub-NUT spacetime, we derive radial equations of
motion with effective potentials and the Euler equation for steady state
axisymmetric fluid. Higher dimensional global embeddings are constructed inside
and outside the event horizons of the Taub-NUT spacetime. We also study the
effective potentials of particles on the Taub-NUT spacetime in terms of
gravitational magnetic monopole strength of the source, total energy and
angular momentum per unit rest mass of the particle.
| [
{
"created": "Sun, 23 May 2010 04:42:32 GMT",
"version": "v1"
}
] | 2010-05-25 | [
[
"Hong",
"Soon-Tae",
""
],
[
"Kim",
"Sung-Won",
""
]
] | On Taub-NUT spacetime, we investigate hydrodynamic properties of perfect fluid spiraling inward toward the spacetime along a conical surface. On the equatorial plane of the Taub-NUT spacetime, we derive radial equations of motion with effective potentials and the Euler equation for steady state axisymmetric fluid. Higher dimensional global embeddings are constructed inside and outside the event horizons of the Taub-NUT spacetime. We also study the effective potentials of particles on the Taub-NUT spacetime in terms of gravitational magnetic monopole strength of the source, total energy and angular momentum per unit rest mass of the particle. |
1306.0394 | Sourav Sur | Sourav Sur and Arshdeep Singh Bhatia | Constraining Torsion in Maximally symmetric (sub)spaces | 20 pages, No figures, 2 Tables | Class. Quant. Grav. 31 (2014) 025020 | 10.1088/0264-9381/31/2/025020 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We look into the general aspects of space-time symmetries in presence of
torsion, and how the latter is affected by such symmetries. Focusing in
particular to space-times which either exhibit maximal symmetry on their own,
or could be decomposed to maximally symmetric subspaces, we work out the
constraints on torsion in two different theoretical schemes. We show that at
least for a completely antisymmetric torsion tensor (for e.g. the one motivated
from string theory), an equivalence is set between these two schemes, as the
non-vanishing independent torsion tensor components turn out to be the same.
| [
{
"created": "Mon, 3 Jun 2013 13:14:21 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Aug 2017 09:04:08 GMT",
"version": "v2"
}
] | 2017-08-18 | [
[
"Sur",
"Sourav",
""
],
[
"Bhatia",
"Arshdeep Singh",
""
]
] | We look into the general aspects of space-time symmetries in presence of torsion, and how the latter is affected by such symmetries. Focusing in particular to space-times which either exhibit maximal symmetry on their own, or could be decomposed to maximally symmetric subspaces, we work out the constraints on torsion in two different theoretical schemes. We show that at least for a completely antisymmetric torsion tensor (for e.g. the one motivated from string theory), an equivalence is set between these two schemes, as the non-vanishing independent torsion tensor components turn out to be the same. |
1807.07649 | Leandro A. Oliveira | Leandro A. Oliveira, Luis J. Garay, Lu\'is C. B. Crispino | Ergoregion instability of a rotating quantum system | 9 pages, 3 figures, 1 table | Physical Review D 97, 124063 (2018) | 10.1103/PhysRevD.97.124063 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the analogy between acoustic perturbations in an ideal fluid and the
description of a Klein-Gordon scalar field in a curved spacetime, we study the
quasinormal modes of a quantum system: the rotating Bose-Einstein condensate.
To compute quasinormal frequencies, we use two different numerical techniques,
namely the direct integration and the continued-fraction methods. We study in
detail the ergoregion instability of this linearly perturbed system, comparing
the results with different setup configurations.
| [
{
"created": "Thu, 19 Jul 2018 21:46:58 GMT",
"version": "v1"
}
] | 2018-07-23 | [
[
"Oliveira",
"Leandro A.",
""
],
[
"Garay",
"Luis J.",
""
],
[
"Crispino",
"Luís C. B.",
""
]
] | Using the analogy between acoustic perturbations in an ideal fluid and the description of a Klein-Gordon scalar field in a curved spacetime, we study the quasinormal modes of a quantum system: the rotating Bose-Einstein condensate. To compute quasinormal frequencies, we use two different numerical techniques, namely the direct integration and the continued-fraction methods. We study in detail the ergoregion instability of this linearly perturbed system, comparing the results with different setup configurations. |
2204.00981 | Manuel D. Malaver | Manuel Malaver de la Fuente, Rajan Iyer, Alokananda Kar, Shouvik
Sadhukhan, Sudhaker Upadhyay and Ertan Gudekli | Buchdahl Spacetime with Compact Body Solution of Charged Fluid and
Scalar Field Theory | 21 pages, 22 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The present work contains a discussion on compact stellar body that is
influenced by the effects electromagnetic fields. We have tried to discuss a
solution of Einstein-Maxwell field equation with the interpretation of Buchdahl
spacetime type function. The interior fluid density and anisotropic pressures
have been derived for a charged fluid of compact body which is also continuous
with the Reissner-Nordstrom metric exterior solution. We have discussed the
singularity free interior anisotropic fluid under electromagnetic influence.
The thermodynamics energy conditions and their variation with interior radius
have been discussed here. We have also discussed the physical acceptability of
this new model. Finally we have included the scalar field theory corresponding
to the interior fluid that helped us to discuss teh compact body strange star
evolution with time. The generalized entropy evolution of the compact body has
also been introduced in the discussion of interior fluid evolution analysis
| [
{
"created": "Sun, 3 Apr 2022 03:51:08 GMT",
"version": "v1"
}
] | 2022-04-05 | [
[
"de la Fuente",
"Manuel Malaver",
""
],
[
"Iyer",
"Rajan",
""
],
[
"Kar",
"Alokananda",
""
],
[
"Sadhukhan",
"Shouvik",
""
],
[
"Upadhyay",
"Sudhaker",
""
],
[
"Gudekli",
"Ertan",
""
]
] | The present work contains a discussion on compact stellar body that is influenced by the effects electromagnetic fields. We have tried to discuss a solution of Einstein-Maxwell field equation with the interpretation of Buchdahl spacetime type function. The interior fluid density and anisotropic pressures have been derived for a charged fluid of compact body which is also continuous with the Reissner-Nordstrom metric exterior solution. We have discussed the singularity free interior anisotropic fluid under electromagnetic influence. The thermodynamics energy conditions and their variation with interior radius have been discussed here. We have also discussed the physical acceptability of this new model. Finally we have included the scalar field theory corresponding to the interior fluid that helped us to discuss teh compact body strange star evolution with time. The generalized entropy evolution of the compact body has also been introduced in the discussion of interior fluid evolution analysis |
1812.00728 | Sven Zschocke | Sven Zschocke | Light propagation in 2PN approximation in the field of one moving
monopole II. Boundary value problem | 68 pages, 4 figures | Classical and Quantum Gravity 36 (2019) 015007 | 10.1088/1361-6382/aaeb4c | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this investigation the boundary value problem of light propagation in the
gravitational field of one arbitrarily moving body with monopole structure is
considered in the second post-Newtonian approximation. The solution of the
boundary value problem comprises a set of altogether three transformations: k
-> sigma and sigma -> n and k -> n. Analytical solutions of these
transformations are given and the upper limit of each individual term is
determined. Based on these results, simplified transformations are obtained by
keeping only those terms relevant for the given goal accuracy of 1
nano-arcsecond in light deflection. Like in case of light propagation in the
gravitational field of one body at rest, there are so-called enhanced terms
which are of second post-Newtonian order but contain one and the same typical
large numerical factor. Finally, the impact of enhanced terms beyond 2PN
approximation is considered. It is found that enhanced 3PN terms are relevant
for astrometry on the level of 1 nano-arcsecond in light deflection, while
enhanced 4PN terms are negligible, except for grazing rays at the Sun.
| [
{
"created": "Mon, 3 Dec 2018 13:36:45 GMT",
"version": "v1"
}
] | 2018-12-26 | [
[
"Zschocke",
"Sven",
""
]
] | In this investigation the boundary value problem of light propagation in the gravitational field of one arbitrarily moving body with monopole structure is considered in the second post-Newtonian approximation. The solution of the boundary value problem comprises a set of altogether three transformations: k -> sigma and sigma -> n and k -> n. Analytical solutions of these transformations are given and the upper limit of each individual term is determined. Based on these results, simplified transformations are obtained by keeping only those terms relevant for the given goal accuracy of 1 nano-arcsecond in light deflection. Like in case of light propagation in the gravitational field of one body at rest, there are so-called enhanced terms which are of second post-Newtonian order but contain one and the same typical large numerical factor. Finally, the impact of enhanced terms beyond 2PN approximation is considered. It is found that enhanced 3PN terms are relevant for astrometry on the level of 1 nano-arcsecond in light deflection, while enhanced 4PN terms are negligible, except for grazing rays at the Sun. |
gr-qc/0303090 | Kouji Nakamura | Kouji Nakamura | Gauge Invariant Variables in Two-Parameter Nonlinear Perturbations | 33 pages, 1 figure, PTPTeX ver.0.8 (LateX2e), Accepted for
Publication to Progress of Theoretical Physics. Typos and trivial mistakes in
equations are corrected | Prog.Theor.Phys. 110 (2003) 723-755 | 10.1143/PTP.110.723 | NAOJ-TH-Ap 2003, No.19 | gr-qc astro-ph hep-ph hep-th math-ph math.MP | null | The procedure to find gauge invariant variables for two-parameter nonlinear
perturbations in general relativity is considered. For each order metric
perturbation, we define the variable which is defined by the appropriate
combination with lower order metric perturbations. Under the gauge
transformation, this variable is transformed in the manner similar to the gauge
transformation of the linear order metric perturbation. We confirm this up to
third order. This implies that gauge invariant variables for higher order
metric perturbations can be found by using a procedure similar to that for
linear order metric perturbations. We also derive gauge invariant combinations
for the perturbation of an arbitrary physical variable, other than the
spacetime metric, up to third order.
| [
{
"created": "Mon, 24 Mar 2003 07:51:46 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Jun 2003 14:34:00 GMT",
"version": "v2"
},
{
"created": "Mon, 28 Jul 2003 21:09:49 GMT",
"version": "v3"
},
{
"created": "Mon, 29 Sep 2003 08:12:47 GMT",
"version": "v4"
}
] | 2009-11-10 | [
[
"Nakamura",
"Kouji",
""
]
] | The procedure to find gauge invariant variables for two-parameter nonlinear perturbations in general relativity is considered. For each order metric perturbation, we define the variable which is defined by the appropriate combination with lower order metric perturbations. Under the gauge transformation, this variable is transformed in the manner similar to the gauge transformation of the linear order metric perturbation. We confirm this up to third order. This implies that gauge invariant variables for higher order metric perturbations can be found by using a procedure similar to that for linear order metric perturbations. We also derive gauge invariant combinations for the perturbation of an arbitrary physical variable, other than the spacetime metric, up to third order. |
1908.11058 | Matt Visser | Matt Visser (Victoria University of Wellington) | The Kiselev black hole is neither perfect fluid, nor is it quintessence | 12 pages | null | 10.1088/1361-6382/ab60b8 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Kiselev black hole spacetime, \[ ds^2 = - \left(1-{2m\over r} - {K\over
r^{1+3w}} \right) dt^2 + {dr^2\over1-{2m\over r} - {K\over r^{1+3w}}} + r^2
\,d\Omega_2^2, \] is an extremely popular toy model, with over 200 direct and
indirect citations as of 2019. Unfortunately, despite repeated assertions to
the contrary, this is not a perfect fluid spacetime. The relative pressure
anisotropy and average pressure are easily calculated to satisfy \[ \Delta =
{\Delta p\over \bar p} = {p_r - p_t \over {1\over3} (p_r+2p_t)} =- {3(1+w)\over
2 w}; \qquad\qquad {\bar p\over \rho} = {{1\over3} (p_r + 2p_t)\over \rho} = w.
\] The relative pressure anisotropy $\Delta$ is generally a non-zero constant,
(unless $w=-1$, corresponding to Schwarzschild-(anti)-de Sitter spacetime).
Kiselev's original paper was very careful to point this out in the calculation,
but then in the discussion made a somewhat unfortunate choice of terminology
which has (with very limited exceptions) been copied into the subsequent
literature. Perhaps worse, Kiselev's use of the word "quintessence" does not
match the standard usage in the cosmology community, leading to another level
of unfortunate and unnecessary confusion. Very few of the subsequent follow-up
papers get these points right, so a brief explicit comment is warranted.
| [
{
"created": "Thu, 29 Aug 2019 05:24:04 GMT",
"version": "v1"
}
] | 2020-01-29 | [
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
]
] | The Kiselev black hole spacetime, \[ ds^2 = - \left(1-{2m\over r} - {K\over r^{1+3w}} \right) dt^2 + {dr^2\over1-{2m\over r} - {K\over r^{1+3w}}} + r^2 \,d\Omega_2^2, \] is an extremely popular toy model, with over 200 direct and indirect citations as of 2019. Unfortunately, despite repeated assertions to the contrary, this is not a perfect fluid spacetime. The relative pressure anisotropy and average pressure are easily calculated to satisfy \[ \Delta = {\Delta p\over \bar p} = {p_r - p_t \over {1\over3} (p_r+2p_t)} =- {3(1+w)\over 2 w}; \qquad\qquad {\bar p\over \rho} = {{1\over3} (p_r + 2p_t)\over \rho} = w. \] The relative pressure anisotropy $\Delta$ is generally a non-zero constant, (unless $w=-1$, corresponding to Schwarzschild-(anti)-de Sitter spacetime). Kiselev's original paper was very careful to point this out in the calculation, but then in the discussion made a somewhat unfortunate choice of terminology which has (with very limited exceptions) been copied into the subsequent literature. Perhaps worse, Kiselev's use of the word "quintessence" does not match the standard usage in the cosmology community, leading to another level of unfortunate and unnecessary confusion. Very few of the subsequent follow-up papers get these points right, so a brief explicit comment is warranted. |
gr-qc/0703087 | D. Bar | D. Bar | A possible quantum probability increase of the cylindrical gravitational
field | 58 pages, 3 composite PS Figures (composed of 8 panels). Some
corrections were added to the former version. Also clarifying sentences were
added and some equations were derived and explained | null | null | gr-qc/0703087 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | As known, the cylindrical gravitational field (wave) have been canonically
quantized and its wave function, as the quantum one, interpreted in probability
terms. We show in this work, using quantum Zeno methods, that this probability
may be substantially increased and even approach unity. For that we first show,
in detailed manner, that the cylindrical gravitational field may be discussed
in the commutation number representation. We also discuss this field in the
transverse-traceless (TT) gauge and calculate the related trapped surface.
| [
{
"created": "Fri, 16 Mar 2007 17:39:18 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Mar 2007 14:46:50 GMT",
"version": "v2"
},
{
"created": "Fri, 7 Jan 2011 23:15:39 GMT",
"version": "v3"
}
] | 2011-01-11 | [
[
"Bar",
"D.",
""
]
] | As known, the cylindrical gravitational field (wave) have been canonically quantized and its wave function, as the quantum one, interpreted in probability terms. We show in this work, using quantum Zeno methods, that this probability may be substantially increased and even approach unity. For that we first show, in detailed manner, that the cylindrical gravitational field may be discussed in the commutation number representation. We also discuss this field in the transverse-traceless (TT) gauge and calculate the related trapped surface. |
1204.6372 | Sergey Sushkov | Sergey Sushkov | Realistic cosmological scenario with non-minimal kinetic coupling | 11 pages, 10 figures, submitted to PRD | Phys.Rev. D85, 123520 (2012) | 10.1103/PhysRevD.85.123520 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate cosmological scenarios in the theory of gravity with the
scalar field possessing a non-minimal kinetic coupling to the curvature. It is
shown that the kinetic coupling provides an essentially new inflationary
mechanism. Namely, at early cosmological times the domination of coupling terms
in the field equations guarantees the quasi-De Sitter behavior of the scale
factor: $a(t)\propto e^{H_{\kappa} t}$ with $H_\kappa=1/\sqrt{9\kappa}$, where
$\kappa\simeq 10^{-74}$ sec$^2$ is the coupling parameter. The primary
inflationary epoch driven by non-minimal kinetic coupling comes to the end at
$t_f \simeq 10^{-35}$ sec. Later on, the matter terms are dominating, and the
universe enters into the matter-dominated epoch which lasts approximately
$0.5H_0^{-1}\sim 0.5\times10^{18}$ sec. Then, the cosmological term comes into
play, and the universe enters into the secondary inflationary epoch with
$a(t)\propto e^{H_{\Lambda} t}$, where $H_\Lambda=\sqrt{\Lambda/3}$. Note that
the present value of the acceleration parameter $q=\ddot a a/\dot a^2$ is
estimated as $q_0\simeq0.25$, that is the universe is at the beginning of the
epoch of accelerated expansion. Thus, the cosmological model non-minimal
kinetic coupling represents the realistic cosmological scenario which
successfully describes basic cosmological epochs and provide the natural
mechanism of epoch change without any fine-tuned potential.
| [
{
"created": "Sat, 28 Apr 2012 06:38:52 GMT",
"version": "v1"
}
] | 2012-10-09 | [
[
"Sushkov",
"Sergey",
""
]
] | We investigate cosmological scenarios in the theory of gravity with the scalar field possessing a non-minimal kinetic coupling to the curvature. It is shown that the kinetic coupling provides an essentially new inflationary mechanism. Namely, at early cosmological times the domination of coupling terms in the field equations guarantees the quasi-De Sitter behavior of the scale factor: $a(t)\propto e^{H_{\kappa} t}$ with $H_\kappa=1/\sqrt{9\kappa}$, where $\kappa\simeq 10^{-74}$ sec$^2$ is the coupling parameter. The primary inflationary epoch driven by non-minimal kinetic coupling comes to the end at $t_f \simeq 10^{-35}$ sec. Later on, the matter terms are dominating, and the universe enters into the matter-dominated epoch which lasts approximately $0.5H_0^{-1}\sim 0.5\times10^{18}$ sec. Then, the cosmological term comes into play, and the universe enters into the secondary inflationary epoch with $a(t)\propto e^{H_{\Lambda} t}$, where $H_\Lambda=\sqrt{\Lambda/3}$. Note that the present value of the acceleration parameter $q=\ddot a a/\dot a^2$ is estimated as $q_0\simeq0.25$, that is the universe is at the beginning of the epoch of accelerated expansion. Thus, the cosmological model non-minimal kinetic coupling represents the realistic cosmological scenario which successfully describes basic cosmological epochs and provide the natural mechanism of epoch change without any fine-tuned potential. |
2005.04130 | Daniela Pugliese Dr | D. Pugliese and H. Quevedo | Kerr metric bundles. Killing horizons confinement, light-surfaces and
horizons replicas | 44 pages; 29 figures; 1 table | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a complete characterization of the metric Killing bundles (or
metric bundles) of the Kerr geometry. Metric bundles, first introduced in [21]
can be generally defined for axially symmetric spacetimes with Killing horizons
and, for the case of Kerr geometries, are sets of black holes (BHs) or black
holes and naked singularities (NSs) geometries. Each metric of a bundle has an
equal limiting photon (orbital) frequency, which defines the bundle and
coincides with the frequency of a Killing horizon in the extended plane. In
this plane each bundle is represented as a curve tangent to the curve that
represents the horizons, which thus emerge as the envelope surfaces of the
metric bundles. We show that the horizons frequency can be used to establish a
connection between BHs and NSs, providing an alternative representation of such
spacetimes in the extended plane and an alternative definition of the BH
horizons. We introduce the concept of inner horizon confinement and horizons
replicas and study the possibility of detecting their frequencies. We study the
bundle characteristic frequencies constraining the inner horizon confinement in
the outer region of the plane i.e. the possibility of detect frequency related
to the inner horizon, and the horizons replicas, structures which may be
detectable, for example, from the emission spectra of BHs spacetimes. It is
shown that such observations can be performed close to the rotation axis of the
Kerr geometry, depending on the BH spin. We argue that these results could be
used to further investigate black holes and their thermodynamic properties.
| [
{
"created": "Fri, 8 May 2020 16:15:17 GMT",
"version": "v1"
}
] | 2020-05-11 | [
[
"Pugliese",
"D.",
""
],
[
"Quevedo",
"H.",
""
]
] | We provide a complete characterization of the metric Killing bundles (or metric bundles) of the Kerr geometry. Metric bundles, first introduced in [21] can be generally defined for axially symmetric spacetimes with Killing horizons and, for the case of Kerr geometries, are sets of black holes (BHs) or black holes and naked singularities (NSs) geometries. Each metric of a bundle has an equal limiting photon (orbital) frequency, which defines the bundle and coincides with the frequency of a Killing horizon in the extended plane. In this plane each bundle is represented as a curve tangent to the curve that represents the horizons, which thus emerge as the envelope surfaces of the metric bundles. We show that the horizons frequency can be used to establish a connection between BHs and NSs, providing an alternative representation of such spacetimes in the extended plane and an alternative definition of the BH horizons. We introduce the concept of inner horizon confinement and horizons replicas and study the possibility of detecting their frequencies. We study the bundle characteristic frequencies constraining the inner horizon confinement in the outer region of the plane i.e. the possibility of detect frequency related to the inner horizon, and the horizons replicas, structures which may be detectable, for example, from the emission spectra of BHs spacetimes. It is shown that such observations can be performed close to the rotation axis of the Kerr geometry, depending on the BH spin. We argue that these results could be used to further investigate black holes and their thermodynamic properties. |
gr-qc/0504111 | Jorge L. Cervantes-Cota | M. A. Rodriguez-Meza, Jorge L. Cervantes-Cota, M. I. Pedraza, J. F.
Tlapanco, and E. M. De la Calleja | Potential-density pairs for axisymmetric galaxies: the influence of
scalar fields | 8 pages, no figures, corrected version to the one that will appear in
Gen. Relativ. Gravit., where a small typo in eq. (13) is present | Gen.Rel.Grav.37:823-829,2005 | 10.1007/s10714-005-0067-2 | null | gr-qc astro-ph | null | We present a formulation for potential-density pairs to describe axisymmetric
galaxies in the Newtonian limit of scalar-tensor theories of gravity. The
scalar field is described by a modified Helmholtz equation with a source that
is coupled to the standard Poisson equation of Newtonian gravity. The net
gravitational force is given by two contributions: the standard Newtonian
potential plus a term stemming from massive scalar fields. General solutions
have been found for axisymmetric systems and the multipole expansion of the
Yukawa potential is given. In particular, we have computed potential-density
pairs of galactic disks for an exponential profile and their rotation curves.
| [
{
"created": "Fri, 22 Apr 2005 15:19:39 GMT",
"version": "v1"
}
] | 2010-11-19 | [
[
"Rodriguez-Meza",
"M. A.",
""
],
[
"Cervantes-Cota",
"Jorge L.",
""
],
[
"Pedraza",
"M. I.",
""
],
[
"Tlapanco",
"J. F.",
""
],
[
"De la Calleja",
"E. M.",
""
]
] | We present a formulation for potential-density pairs to describe axisymmetric galaxies in the Newtonian limit of scalar-tensor theories of gravity. The scalar field is described by a modified Helmholtz equation with a source that is coupled to the standard Poisson equation of Newtonian gravity. The net gravitational force is given by two contributions: the standard Newtonian potential plus a term stemming from massive scalar fields. General solutions have been found for axisymmetric systems and the multipole expansion of the Yukawa potential is given. In particular, we have computed potential-density pairs of galactic disks for an exponential profile and their rotation curves. |
gr-qc/0607008 | Carlos Barcelo | Carlos Barcelo, Stefano Liberati, Sebastiano Sonego, Matt Visser | Hawking-like radiation does not require a trapped region | revtex4, 4 pages, 1 figure | Phys.Rev.Lett. 97 (2006) 171301 | 10.1103/PhysRevLett.97.171301 | null | gr-qc | null | We discuss the issue of quasi-particle production by ``analogue black holes''
with particular attention to the possibility of reproducing Hawking radiation
in a laboratory. By constructing simple geometric acoustic models, we obtain a
somewhat unexpected result: We show that in order to obtain a stationary and
Planckian emission of quasi-particles, it is not necessary to create a trapped
region in the acoustic spacetime (corresponding to a supersonic regime in the
fluid flow). It is sufficient to set up a dynamically changing flow
asymptotically approaching a sonic regime with sufficient rapidity in
laboratory time.
| [
{
"created": "Mon, 3 Jul 2006 12:00:50 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Barcelo",
"Carlos",
""
],
[
"Liberati",
"Stefano",
""
],
[
"Sonego",
"Sebastiano",
""
],
[
"Visser",
"Matt",
""
]
] | We discuss the issue of quasi-particle production by ``analogue black holes'' with particular attention to the possibility of reproducing Hawking radiation in a laboratory. By constructing simple geometric acoustic models, we obtain a somewhat unexpected result: We show that in order to obtain a stationary and Planckian emission of quasi-particles, it is not necessary to create a trapped region in the acoustic spacetime (corresponding to a supersonic regime in the fluid flow). It is sufficient to set up a dynamically changing flow asymptotically approaching a sonic regime with sufficient rapidity in laboratory time. |
gr-qc/9611017 | Shin'ji Mukouyama | Shinji Mukohyama | New Proof of the Generalized Second Law | 13 pages, Latex | Phys.Rev. D56 (1997) 2192-2201 | 10.1103/PhysRevD.56.2192 | YITP-96-38 | gr-qc | null | The generalized second law of black hole thermodynamics was proved by Frolov
and Page for a quasi-stationary eternal black hole. However, realistic black
holes arise from a gravitational collapse, and in this case their proof does
not hold. In this paper we prove the generalized second law for a
quasi-stationary black hole which arises from a gravitational collapse.
| [
{
"created": "Thu, 7 Nov 1996 08:45:39 GMT",
"version": "v1"
},
{
"created": "Sat, 28 Dec 1996 05:58:32 GMT",
"version": "v2"
},
{
"created": "Tue, 6 May 1997 10:03:46 GMT",
"version": "v3"
}
] | 2009-10-28 | [
[
"Mukohyama",
"Shinji",
""
]
] | The generalized second law of black hole thermodynamics was proved by Frolov and Page for a quasi-stationary eternal black hole. However, realistic black holes arise from a gravitational collapse, and in this case their proof does not hold. In this paper we prove the generalized second law for a quasi-stationary black hole which arises from a gravitational collapse. |
2008.10600 | Sunil Maurya DR. | S. K. Maurya, Ksh. Newton Singh, M. Govender, Abdelghani Errehymy | Charged anisotropic strange stars in Brans-Dicke gravity with a massive
scalar field through embedding approach | 9 figures and 6 tables | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this exposition, we seek solutions of the Einstein-Maxwell field equations
in the presence of a massive scalar field cast in the Brans-Dicke (BD)
formalism which describes charged anisotropic strange stars. The interior
spacetime is described by a spherically symmetric static metric of embedding
class I. This reduces the problem to a single-generating function of the metric
potential which is chosen by appealing to physics based on regularity at each
interior point of the stellar interior. The resulting model is subjected to
rigorous physical checks based on stability, causality and regularity. We show
that our solutions describe compact objects such as PSR J1903+327; Cen X-3; EXO
1785-248 \& LMC X-4 to an excellent approximation. Novel results of our
investigation reveal that the scalar field leads to higher surface charge
densities which in turn affects the compactness and upper and lower values
imposed by the modified Buchdahl limit for charged stars. Our results also show
that the electric and scalar fields which originate from entirely different
sources couple to alter physical characteristics such as mass-radius relation
and surface redshift of compact objects. This superposition of the electric and
scalar fields is enhanced by an increase in the BD coupling constant,
$\omega_{BD}$.
| [
{
"created": "Sun, 23 Aug 2020 19:18:52 GMT",
"version": "v1"
},
{
"created": "Sun, 6 Dec 2020 14:16:45 GMT",
"version": "v2"
}
] | 2020-12-08 | [
[
"Maurya",
"S. K.",
""
],
[
"Singh",
"Ksh. Newton",
""
],
[
"Govender",
"M.",
""
],
[
"Errehymy",
"Abdelghani",
""
]
] | In this exposition, we seek solutions of the Einstein-Maxwell field equations in the presence of a massive scalar field cast in the Brans-Dicke (BD) formalism which describes charged anisotropic strange stars. The interior spacetime is described by a spherically symmetric static metric of embedding class I. This reduces the problem to a single-generating function of the metric potential which is chosen by appealing to physics based on regularity at each interior point of the stellar interior. The resulting model is subjected to rigorous physical checks based on stability, causality and regularity. We show that our solutions describe compact objects such as PSR J1903+327; Cen X-3; EXO 1785-248 \& LMC X-4 to an excellent approximation. Novel results of our investigation reveal that the scalar field leads to higher surface charge densities which in turn affects the compactness and upper and lower values imposed by the modified Buchdahl limit for charged stars. Our results also show that the electric and scalar fields which originate from entirely different sources couple to alter physical characteristics such as mass-radius relation and surface redshift of compact objects. This superposition of the electric and scalar fields is enhanced by an increase in the BD coupling constant, $\omega_{BD}$. |
2403.10606 | Swagat Saurav Mishra | Swagat S. Mishra | Cosmic Inflation: Background dynamics, Quantum fluctuations and
Reheating | 117 pages, 26 figures, preliminary version (based on a set of
supplementary lectures delivered for the PhD coursework at IUCAA), comments
and suggestions are welcome | null | null | null | gr-qc astro-ph.CO hep-ph hep-th | http://creativecommons.org/licenses/by/4.0/ | These lecture notes provide a pedagogical introduction to some aspects of the
inflationary cosmology, including the background scalar field dynamics,
generation of primordial seed perturbations via quantum fluctuations during
inflation, and the process of reheating after inflation in the single-field
inflationary paradigm.
| [
{
"created": "Fri, 15 Mar 2024 18:00:59 GMT",
"version": "v1"
}
] | 2024-03-19 | [
[
"Mishra",
"Swagat S.",
""
]
] | These lecture notes provide a pedagogical introduction to some aspects of the inflationary cosmology, including the background scalar field dynamics, generation of primordial seed perturbations via quantum fluctuations during inflation, and the process of reheating after inflation in the single-field inflationary paradigm. |
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