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Author  |
Guerrero, M.; Mora-Perez, G.; Olmo, G.J.; Orazi, E.; Rubiera-Garcia, D. |
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Title |
Charged BTZ-type solutions in Eddington-inspired Born-Infeld gravity |
Type |
Journal Article |
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Year |
2021 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
11 |
Issue |
11 |
Pages |
025 - 23pp |
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Keywords |
modified gravity; Exact solutions; black holes and black hole thermodynamics in GR and beyond; Wormholes |
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Abstract |
We construct an axially symmetric solution of Eddington-inspired Born-Infeld gravity coupled to an electromagnetic field in 2 + 1 dimensions including a (negative) cosmological constant term. This is achieved by using a recently developed mapping procedure that allows to generate solutions in certain families of metric-affine gravity theories starting from a known seed solution of General Relativity, which in the present case corresponds to the electrically charged Banados-Teitelboim-Zanelli (BTZ) solution. We discuss the main features of the new configurations, including the modifications to the ergospheres and horizons, the emergence of wormhole structures, and the consequences for the regularity (or not) of these space-times via geodesic completeness. |
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Address |
[Guerrero, Merce; Rubiera-Garcia, Diego] Univ Complutense Madrid, Dept Fis Teor, Plaza Ciencias S-N, E-28040 Madrid, Spain, Email: merguerr@ucm.es; |
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Publisher |
IOP Publishing Ltd |
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English |
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ISSN |
1475-7516 |
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Notes |
WOS:000727716400006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5050 |
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Author |
Guendelman, E.I.; Olmo, G.J.; Rubiera-Garcia, D.; Vasihoun, M. |
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Title |
Nonsingular electrovacuum solutions with dynamically generated cosmological constant |
Type |
Journal Article |
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Year |
2013 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
726 |
Issue |
4-5 |
Pages |
870-875 |
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Keywords |
Modified gravity; Palatini formalism; Nonlinear electrodynamics; Dynamical cosmological constant; Nonsingular solutions; Wormholes |
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Abstract |
We consider static spherically symmetric configurations in a Palatini extension of General Relativity including R-2 and Ricci-squared terms, which is known to replace the central singularity by a wormhole in the electrovacuum case. We modify the matter sector of the theory by adding to the usual Maxwell term a nonlinear electromagnetic extension which is known to implement a confinement mechanism in flat space. One feature of the resulting theory is that the nonlinear electric field leads to a dynamically generated cosmological constant. We show that with this matter source the solutions of the model are asymptotically de Sitter and possess a wormhole topology. We discuss in some detail the conditions that guarantee the absence of singularities and of traversable wormholes. |
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Address |
[Guendelman, E. I.; Vasihoun, M.] Ben Gurion Univ Negev, Dept Phys, IL-84105 Beer Sheva, Israel, Email: guendel@bgumail.bgu.ac.il; |
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Publisher |
Elsevier Science Bv |
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English |
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ISSN |
0370-2693 |
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Notes |
WOS:000327907000045 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1680 |
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Author |
Dias da Silva, L.F.; Lobo, F.S.N.; Olmo, G.J.; Rubiera-Garcia, D. |
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Title |
Photon rings as tests for alternative spherically symmetric geometries with thin accretion disks |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
108 |
Issue |
8 |
Pages |
084055 - 18pp |
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Abstract |
The imaging by the Event Horizon Telescope (EHT) of the supermassive central objects at the heart of the M87 and Milky Way (Sgr A*) galaxies, has marked the first step into peering at the photon rings and central brightness depression that characterize the optical appearance of black holes surrounded by an accretion disk. Recently, Vagnozzi et al. [arXiv:2205.07787] used the claim by the EHT that the size of the shadow of Sgr A* can be inferred by calibrated measurements of the bright ring enclosing it, to constrain a large number of spherically symmetric space-time geometries. In this work we use this result to study some features of the first and second photon rings of a restricted pool of such geometries in thin accretion disk settings. The emission profile of the latter is described by calling upon three analytic samples belonging to the family introduced by Gralla, Lupsasca, and Marrone, in order to characterize such photon rings using the Lyapunov exponent of nearly bound orbits and discuss its correlation with the luminosity extinction rate between the first and second photon rings. We finally elaborate on the chances of using such photon rings as observational discriminators of alternative black hole geometries using very long baseline interferometry. |
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Address |
[Dias da Silva, Luis F.; Lobo, Francisco S. N.] Univ Lisbon, Inst Astrofis & Ciencias Espaco, Fac Ciencias, Edificio C8, P-1749016 Lisbon, Portugal, Email: fc53497@alunos.fc.ul.pt; |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2470-0010 |
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Notes |
WOS:001093442700002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5779 |
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Author |
Delhom-Latorre, A.; Olmo, G.J.; Ronco, M. |
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Title |
Observable traces of non-metricity: New constraints on metric-affine gravity |
Type |
Journal Article |
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Year |
2018 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
780 |
Issue |
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Pages |
294-299 |
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Abstract |
Relaxing the Riemannian condition to incorporate geometric quantities such as torsion and non-metricity may allow to explore new physics associated with defects in a hypothetical space-time microstructure. Here we show that non-metricity produces observable effects in quantum fields in the form of 4-fermion contact interactions, thereby allowing us to constrain the scale of non-metricity to be greater than 1 TeV by using results on Bahbah scattering. Our analysis is carried out in the framework of a wide class of theories of gravity in the metric-affine approach. The bound obtained represents an improvement of several orders of magnitude to previous experimental constraints. |
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Address |
[Delhom-Latorre, Adria; Olmo, Gonzalo J.] Univ Valencia, Dept Fis Teor, E-46100 Valencia, Spain, Email: adria.delhom@uv.es; |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0370-2693 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000432187800045 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3617 |
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Author |
Delhom, A.; Olmo, G.J.; Singh, P. |
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Title |
A diffeomorphism invariant family of metric-affine actions for loop cosmologies |
Type |
Journal Article |
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Year |
2023 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
06 |
Issue |
6 |
Pages |
059 - 21pp |
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Keywords |
quantum cosmology; modified gravity; cosmic singularity |
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Abstract |
In loop quantum cosmology (LQC) the big bang singularity is generically resolved by a big bounce. This feature holds even when modified quantization prescriptions of the Hamiltonian constraint are used such as in mLQC-I and mLQC-II. While the later describes an effective description qualitatively similar to that of standard LQC, the former describes an asymmetric evolution with an emergent Planckian de-Sitter pre-bounce phase even in the absence of a potential. We consider the potential relation of these canonically quantized non-singular models with effective actions based on a geometric description. We find a 3-parameter family of metric-affine f (R) theories which accurately approximate the effective dynamics of LQC and mLQC-II in all regimes and mLQC-I in the post-bounce phase. Two of the parameters are fixed by enforcing equivalence at the bounce, and the background evolution of the relevant observables can be fitted with only one free parameter. It is seen that the non-perturbative effects of these loop cosmologies are universally encoded by a logarithmic correction that only depends on the bounce curvature of the model. In addition, we find that the best fit value of the free parameter can be very approximately written in terms of fundamental parameters of the underlying quantum description for the three models. The values of the best fits can be written in terms of the bounce density in a simple manner, and the values for each model are related to one another by a proportionality relation involving only the Barbero-Immirzi parameter. |
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Address |
[Delhom, Adria; Singh, Parampreet] Louisiana State Univ, Dept Phys & Astron, Baton Rouge, LA 70803 USA, Email: adria.delhom@gmail.com; |
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Corporate Author |
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Thesis |
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Publisher |
IOP Publishing Ltd |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1475-7516 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001025410500003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5583 |
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