|
Records |
Links |
|
Author |
Olmo, G.J.; Rosa, J.L.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D. |
|
|
Title |
Shadows and photon rings of regular black holes and geonic horizonless compact objects |
Type |
Journal Article |
|
Year |
2023 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
|
|
Volume |
40 |
Issue |
17 |
Pages |
174002 - 37pp |
|
|
Keywords |
black holes; compact objects; photon rings; shadows; metric-affine gravity; Born-Infeld gravity; regular solutions |
|
|
Abstract |
The optical appearance of a body compact enough to feature an unstable bound orbit, when surrounded by an accretion disk, is expected to be dominated by a luminous ring of radiation enclosing a central brightness depression typically known as the shadow. Despite observational limitations, the rough details of this picture have been now confirmed by the results of the Event Horizon Telescope (EHT) Collaboration on the imaging of the M87 and Milky Way supermassive central objects. However, the precise characterization of both features-ring and shadow-depends on the interaction between the background geometry and the accretion disk, thus being a fertile playground to test our theories on the nature of compact objects and the gravitational field itself in the strong-field regime. In this work we use both features in order to test a continuous family of solutions interpolating between regular black holes and horizonless compact objects, which arise within the Eddington-inspired Born-Infeld theory of gravity, a viable extension of Einstein's general relativity (GR). To this end we consider seven distinctive classes of such configurations (five black holes and two traversable wormholes) and study their optical appearances under illumination by a geometrically and optically thin accretion disk, emitting monochromatically with three analytic intensity profiles previously suggested in the literature. We build such images and consider the sub-ring structure created by light rays crossing the disk more than once and existing on top of the main ring of radiation. We discuss in detail the modifications as compared to their GR counterparts, the Lyapunov exponents of unstable nearly-bound orbits, as well as the differences between black hole and traversable wormholes for the three intensity profiles. In addition we use the claim by the EHT Collaboration on the radius of the bright ring acting (under proper calibrations) as a proxy for the radius of the shadow itself to explore the parameter space of our solutions compatible with such a result. |
|
|
Address |
[Olmo, Gonzalo J.] Univ Valencia, Ctr Mixto Univ Valencia, Dept Fis Teor, CSIC, Burjassot 46100, Valencia, Spain, Email: drubiera@ucm.es |
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
IOP Publishing Ltd |
Place of Publication |
|
Editor |
|
|
|
Language |
English |
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
0264-9381 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
WOS:001043720300001 |
Approved |
no |
|
|
Is ISI |
yes |
International Collaboration |
yes |
|
|
Call Number |
IFIC @ pastor @ |
Serial |
5600 |
|
Permanent link to this record |
|
|
|
|
Author |
Magalhaes, R.B.; Maso-Ferrando, A.; Olmo, G.J.; Crispino, L.C.B. |
|
|
Title |
Asymmetric wormholes in Palatini f (R) gravity: Energy conditions, absorption, and quasibound states |
Type |
Journal Article |
|
Year |
2023 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
|
|
Volume |
108 |
Issue |
2 |
Pages |
024063 - 20pp |
|
|
Keywords |
|
|
|
Abstract |
We investigate the scalar absorption spectrum of wormhole solutions constructed via the recently developed thin-shell formalism for Palatini f(R) gravity. Such wormholes come from the matching of two Reissner-Nordstrom spacetimes at a timelike hypersurface (shell), which, according to the junction conditions in Palatini f(R), can be stable and have either positive or negative energy density. In particular, we identified a new physically interesting configuration made out of two overcharged Reissner-Nordstrom spacetimes, whose absorption profile departs from that of black holes and other previously considered wormholes in the whole range of frequencies. Unlike in symmetric wormhole solutions, the asymmetry of the effective potential causes the dilution of the resonances associated to the quasibound states for the high -frequency regime. Therefore, slight asymmetries in wormhole space-times could have a dramatic impact on the observable features associated to resonant states. |
|
|
Address |
[Magalhaes, Renan B.; Crispino, Luis C. B.] Univ Fed, Programa Pos Graduacao Fis, BR-66075110 Belem, PA, Brazil, Email: renan.batalha@ext.uv.es; |
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
Amer Physical Soc |
Place of Publication |
|
Editor |
|
|
|
Language |
English |
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2470-0010 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
WOS:001055237800002 |
Approved |
no |
|
|
Is ISI |
yes |
International Collaboration |
yes |
|
|
Call Number |
IFIC @ pastor @ |
Serial |
5629 |
|
Permanent link to this record |
|
|
|
|
Author |
Nascimento, J.R.; Olmo, G.J.; Petrov, A.Y.; Porfirio, P.J. |
|
|
Title |
On metric-affine bumblebee model coupled to scalar matter |
Type |
Journal Article |
|
Year |
2024 |
Publication |
Nuclear Physics B |
Abbreviated Journal |
Nucl. Phys. B |
|
|
Volume |
1004 |
Issue |
|
Pages |
116577 - 10pp |
|
|
Keywords |
|
|
|
Abstract |
We consider the coupling of the metric-affine bumblebee gravity model to scalar matter and calculate the lower -order contributions to two -point functions of bumblebee and scalar fields in the weak gravity approximation. We also obtain the one -loop effective potentials for both scalar and vector fields. |
|
|
Address |
[Nascimento, J. R.; Petrov, A. Yu.; Porfirio, P. J.] Univ Fed Paraiba, Dept Fis, Caixa Postal 5008, BR-58051970 Joao Pessoa, PB, Brazil, Email: jroberto@fisica.ufpb.br; |
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
Elsevier |
Place of Publication |
|
Editor |
|
|
|
Language |
English |
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
0550-3213 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
WOS:001248177100001 |
Approved |
no |
|
|
Is ISI |
yes |
International Collaboration |
yes |
|
|
Call Number |
IFIC @ pastor @ |
Serial |
6157 |
|
Permanent link to this record |
|
|
|
|
Author |
Guerrero, M.; Olmo, G.J.; Rubiera-Garcia, D. |
|
|
Title |
Geodesic completeness of effective null geodesics in regular space-times with non-linear electrodynamics |
Type |
Journal Article |
|
Year |
2023 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
|
|
Volume |
83 |
Issue |
9 |
Pages |
785 - 8pp |
|
|
Keywords |
|
|
|
Abstract |
We study the completeness of light trajectories in certain spherically symmetric regular geometries found in Palatini theories of gravity threaded by non-linear (electromagnetic) fields, which makes their propagation to happen along geodesics of an effective metric. Two types of geodesic restoration mechanisms are employed: by pushing the focal point to infinite affine distance, thus unreachable in finite time by any sets of geodesics, or by the presence of a defocusing surface associated to the development of a wormhole throat. We discuss several examples of such geometries to conclude the completeness of all such effective paths. Our results are of interest both for the finding of singularity-free solutions and for the analysis of their optical appearances e.g. in shadow observations. |
|
|
Address |
[Guerrero, Merce; Rubiera-Garcia, Diego] Univ Complutense Madrid, Dept Fis Teor, Madrid 28040, Spain, Email: merguerr@ucm.es; |
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
Springer |
Place of Publication |
|
Editor |
|
|
|
Language |
English |
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
1434-6044 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
WOS:001065963300005 |
Approved |
no |
|
|
Is ISI |
yes |
International Collaboration |
yes |
|
|
Call Number |
IFIC @ pastor @ |
Serial |
5710 |
|
Permanent link to this record |
|
|
|
|
Author |
Maso-Ferrando, A.; Sanchis-Gual, N.; Font, J.A.; Olmo, G.J. |
|
|
Title |
Birth of baby universes from gravitational collapse in a modified-gravity scenario |
Type |
Journal Article |
|
Year |
2023 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
|
|
Volume |
06 |
Issue |
6 |
Pages |
028 - 19pp |
|
|
Keywords |
modified gravity; Wormholes |
|
|
Abstract |
We consider equilibrium models of spherical boson stars in Palatini f (R) = R + CR2 gravity and study their collapse when perturbed. The Einstein-Klein-Gordon system is solved using a recently established correspondence in an Einstein frame representation. We find that, in that frame, the endpoint is a nonrotating black hole surrounded by a quasi -stationary cloud of scalar field. However, the dynamics in the f (R) frame is dramatically different. The innermost region of the collapsing object exhibits the formation of a finite -size, exponentially-expanding baby universe connected with the outer (parent) universe via a minimal area surface (a throat or umbilical cord). Our simulations indicate that this surface is at all times hidden inside a horizon, causally disconnecting the baby universe from observers above the horizon. The implications of our findings in other areas of gravitational physics are also discussed. |
|
|
Address |
[Maso-Ferrando, Andreu; Olmo, Gonzalo J.] Univ Valencia, Ctr Mixto, CSIC, Dept Fis Teor, Valencia 46100, Spain, Email: andreu.maso@uv.es; |
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
IOP Publishing Ltd |
Place of Publication |
|
Editor |
|
|
|
Language |
English |
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
1475-7516 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
WOS:001025474200010 |
Approved |
no |
|
|
Is ISI |
yes |
International Collaboration |
yes |
|
|
Call Number |
IFIC @ pastor @ |
Serial |
5577 |
|
Permanent link to this record |