| Records |
| Author |
Lobo, F.S.N.; Olmo, G.J.; Orazi, E.; Rubiera-Garcia, D.; Rustam, A. |
| Title |
Structure and stability of traversable thin-shell wormholes in Palatini f(R) gravity |
Type |
Journal Article |
| Year |
2020 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
| Volume |
102 |
Issue |
10 |
Pages |
104012 - 11pp |
| Keywords |
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| Abstract |
We study the structure and stability of traversable wormholes built as (spherically symmetric) thin shells in the context of Palatini f(R) gravity. Using a suitable junction formalism for these theories we find that the effective number of degrees of freedom on the shell is reduced to a single one, which fixes the equation of state to be that of massless stress-energy fields, contrary to the general relativistic and metric f(R) cases. Another major difference is that the surface energy density threading the thin shell, needed in order to sustain the wormhole, can take any sign and may even vanish, depending on the desired features of the corresponding solutions. We illustrate our results by constructing thin-shell wormholes by surgically grafting Schwarzschild space-times and show that these configurations are always linearly unstable. However, surgically joined Reissner-Nordstrom space-times allow for linearly stable, traversable thin-shell wormholes supported by a positive energy density provided that the (squared) mass-to-charge ratio, given by y = Q(2)/M-2, satisfies the constraint 1 < y < 9/8 (corresponding to overcharged Reissner-Nordstrom configurations having a photon sphere) and lies in a region bounded by specific curves defined in terms of the (dimensionless) radius of the shell x(0) = R/M. |
| Address |
[Lobo, Francisco S. N.] Univ Lisbon, Fac Ciencias, Inst Astrofis & Ciencias Espaco, Edificio C8,Campo Grande, P-1749016 Lisbon, Portugal, Email: fslobo@fc.ul.pt; |
| Corporate Author |
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Thesis |
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| Publisher |
Amer Physical Soc |
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  |
2470-0010 |
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:000587286200006 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
4596 |
| Permanent link to this record |
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| Author |
Olmo, G.J.; Rubiera-Garcia, D.; Wojnar, A. |
| Title |
Parameterized nonrelativistic limit of stellar structure equations in Ricci-based gravity theories |
Type |
Journal Article |
| Year |
2021 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
| Volume |
104 |
Issue |
2 |
Pages |
024045 - 8pp |
| Keywords |
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| Abstract |
We present the nonrelativistic limit of the stellar structure equations of Ricci-based gravities, a family of metric-affine theories whose Lagrangian is built via contractions of the metric with the Ricci tensor of an a priori independent connection. We find that this limit is characterized by four parameters that arise in the expansion of several geometric quantities in powers of the stress-energy tensor of the matter fields. We discuss the relevance of this result for the phenomenology of nonrelativistic stars, such as main-sequence stars as well as several substellar objects. |
| Address |
[Olmo, Gonzalo J.] Univ Valencia, Dept Fis Teor, Ctr Mixto, CSIC, Valencia 46100, Spain, Email: gonzalo.olmo@uv.es; |
| Corporate Author |
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Thesis |
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| Publisher |
Amer Physical Soc |
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 |
2470-0010 |
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:000674579300010 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
4914 |
| Permanent link to this record |
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| Author |
Guerrero, M.; Olmo, G.J.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D. |
| Title |
Light ring images of double photon spheres in black hole and wormhole spacetimes |
Type |
Journal Article |
| Year |
2022 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
| Volume |
105 |
Issue |
8 |
Pages |
084057 - 16pp |
| Keywords |
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| Abstract |
The silhouette of a black hole having a critical curve (an unstable bound photon orbit) when illuminated by an optically thin accretion disk whose emission is confined to the equatorial plane shows a distinctive central brightness depression (the shadow) whose outer edge consists of a series of strongly lensed, selfsimilar rings superimposed with the disk???s direct emission. While the size and shape of the critical curve depend only on the background geometry, the pattern of bright and dark regions (including the size and depth of the shadow itself) in the image is strongly influenced by the (astro)physics of the accretion disk. This aspect makes it difficult to extract clean and clear observational discriminators between the Kerr black hole and other compact objects. In the presence of a second critical curve, however, observational differences become apparent. In this work we shall consider some spherically symmetric black hole and wormhole geometries characterized by the presence of a second critical curve, via a uniparametric family of extensions of the Schwarzschild metric. By assuming three toy models of geometrically thin accretion disks, we show the presence of additional light rings in the intermediate region between the two critical curves. The observation of such rings could represent a compelling evidence for the existence of black hole mimickers having multiple critical curves. |
| Address |
[Guerrero, Merce; Rubiera-Garcia, Diego] Univ Complutense Madrid, Dept Fis Teor, E-28040 Madrid, Spain, Email: merguerr@ucm.es; |
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Thesis |
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| Publisher |
Amer Physical Soc |
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 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 |
2470-0010 |
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:000810908800018 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
5261 |
| Permanent link to this record |
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| Author |
Alvarez-Ortega, D.; Olmo, G.J.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D. |
| Title |
Eternal versus singular observers in interacting dark-energy-dark-matter models |
Type |
Journal Article |
| Year |
2022 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
| Volume |
106 |
Issue |
2 |
Pages |
023523 - 14pp |
| Keywords |
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| Abstract |
Interacting dark-energy-dark-matter models have been widely analyzed in the literature in an attempt to find traces of new physics beyond the usual cosmological (Lambda CDM) models. Such a coupling between both dark components is usually introduced in a phenomenological way through a flux in the continuity equation. However, models with a Lagrangian formulation are also possible. A class of the latter assumes a conformal/disformal coupling that leads to a fifth force on the dark-matter component, which consequently does not follow the same geodesics as the other (baryonic, radiation, and dark-energy) matter sources. Here we analyze how the usual cosmological singularities of the standard matter frame are seen from the dark-matter one, concluding that by choosing an appropriate coupling, dark-matter observers will see no singularities but a non beginning, non ending universe. By considering two simple phenomenological models we show that such a type of coupling can fit observational data as well as the usual Lambda CDM model. |
| Address |
[Alvarez-Ortega, Diego] Inst Fis Cantabria CSIC UC, Avda Castros S-N, Santander 39005, Spain, Email: diego.alvarezo@alumnos.unican.es; |
| Corporate Author |
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Thesis |
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| Publisher |
Amer Physical Soc |
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 |
2470-0010 |
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:000842768300012 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
5345 |
| Permanent link to this record |
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| Author |
Guerrero, M.; Olmo, G.J.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D. |
| Title |
Multiring images of thin accretion disk of a regular naked compact object |
Type |
Journal Article |
| Year |
2022 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
| Volume |
106 |
Issue |
4 |
Pages |
044070 - 13pp |
| Keywords |
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| Abstract |
We discuss the importance of multiring images in the optical appearance of a horizonless spherically symmetric compact object, when illuminated by an optically thin accretion disk. Such an object corresponds to a subcase of an analytically tractable extension of the Kerr solution dubbed as the “eye of the storm” by Simpson and Visser in [J. Cosmol. Astropart. Phys. 03 (2022) 011], which merits in removing curvature singularities via an asymptotically Minkowski core, while harboring both a critical curve and an infinite potential barrier at the center for null geodesics. This multiring structure is induced by light rays winding several times around the object, and whose luminosity is significantly boosted as compared to the Schwarzschild solution by the modified shape of the potential. Using three toy profiles for the emission of an infinitely thin disk, truncated at its inner edge (taking its maximum value there) and having different decays with the distance, we discuss the image created by up to eight rings superimposed on top of the direct emission of the disk as its edge is moved closer to the center of the object. Our results point to the existence of multiring images with a non-negligible luminosity in shadow observations when one allows for the existence of other compact objects in the cosmic zoo beyond the Schwarzschild solution. Such multiring images could be detectable within the future projects on very long baseline interferometry. |
| Address |
[Guerrero, Merce; Rubiera-Garcia, Diego] Univ Complutense Madrid, Dept Fis Teor, IPARCOS, Madrid 28040, Spain, Email: merguerr@ucm.es; |
| Corporate Author |
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Thesis |
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| Publisher |
Amer Physical Soc |
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 |
2470-0010 |
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:000850772800006 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
5352 |
| Permanent link to this record |
