Records |
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 ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
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 ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
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 |
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Author |
Silva, J.E.G.; Maluf, R.V.; Olmo, G.J.; Almeida, C.A.S. |
Title |
Braneworlds in f(Q) gravity |
Type |
Journal Article |
Year |
2022 |
Publication |
Physical Review D |
Abbreviated Journal ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
Phys. Rev. D |
Volume |
106 |
Issue |
2 |
Pages |
024033 - 15pp |
Keywords |
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Abstract |
We propose a braneworld scenario in a modified symmetric teleparallel gravitational theory, where the dynamics for the gravitational field is encoded in the nonmetricity tensor rather than in the curvature. Assuming a single real scalar field with a sine-Gordon self-interaction, the generalized quadratic nonmetricity invariant Q controls the brane width while keeping the shape of the energy density. By considering power corrections of the invariant Q in the gravitational Lagrangian, the sine-Gordon potential is modified exhibiting new barriers and false vacuum. As a result, the domain wall brane obtains an inner structure, and it undergoes a splitting process. In addition, we also propose a nonminimal coupling between a bulk fermion field and the nonmetricity invariant Q. Such geometric coupling leads to a massless chiral fermion bound to the 3-brane and a stable tower of nonlocalized massive states. |
Address |
[Silva, J. E. G.] Univ Fed do Cariri UFCA, Ave Tenente Raimundo Rocha,Cidade Universitaria, BR-63048080 Juazeiro do Norte, CE, Brazil, Email: euclides.silva@ufca.edu.br; |
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:000880673200004 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5410 |
Permanent link to this record |
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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 ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
Phys. Rev. D |
Volume |
108 |
Issue |
2 |
Pages |
024063 - 20pp |
Keywords |
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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 |
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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:001055237800002 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5629 |
Permanent link to this record |
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Author |
Dias da Silva, L.F.; Lobo, F.S.N.; Olmo, G.J.; Rubiera-Garcia, D. |
Title |
Photon rings as tests for alternative spherically symmetric geometries with thin accretion disks |
Type |
Journal Article |
Year |
2023 |
Publication |
Physical Review D |
Abbreviated Journal ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
Phys. Rev. D |
Volume |
108 |
Issue |
8 |
Pages |
084055 - 18pp |
Keywords |
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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. |
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; |
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 |
|
Series Issue |
|
Edition |
|
ISSN |
2470-0010 |
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
WOS:001093442700002 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5779 |
Permanent link to this record |