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Author Guerrero, M.; Olmo, G.J.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D. url  doi
openurl 
  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 (down) 106 Issue 4 Pages 044070 - 13pp  
  Keywords  
  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 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:000850772800006 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5352  
Permanent link to this record
 

 
Author Silva, J.E.G.; Maluf, R.V.; Olmo, G.J.; Almeida, C.A.S. url  doi
openurl 
  Title Braneworlds in f(Q) gravity Type Journal Article
  Year 2022 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume (down) 106 Issue 2 Pages 024033 - 15pp  
  Keywords  
  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 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:000880673200004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5410  
Permanent link to this record
 

 
Author Agullo, I.; Navarro-Salas, J.; Olmo, G.J.; Parker, L. url  doi
openurl 
  Title Hawking Radiation by Kerr Black Holes and Conformal Symmetry Type Journal Article
  Year 2010 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.  
  Volume (down) 105 Issue 21 Pages 211305 - 4pp  
  Keywords  
  Abstract The exponential blueshift associated with the event horizon of a black hole makes conformal symmetry play a fundamental role in accounting for its thermal properties. Using a derivation based on two-point functions, we show that the full spectrum of thermal radiation of scalar particles by Kerr black holes can be explicitly derived on the basis of a conformal symmetry arising in the wave equation near the horizon. The simplicity of our approach emphasizes the depth of the connection between conformal symmetry and black hole radiance.  
  Address [Agullo, Ivan; Parker, Leonard] Univ Wisconsin, Dept Phys, Milwaukee, WI 53201 USA  
  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 0031-9007 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000284407400004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 322  
Permanent link to this record
 

 
Author Magalhaes, R.B.; Crispino, L.C.B.; Olmo, G.J. url  doi
openurl 
  Title Compact objects in quadratic Palatini gravity generated by a free scalar field Type Journal Article
  Year 2022 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume (down) 105 Issue 6 Pages 064007 - 15pp  
  Keywords  
  Abstract We study the correspondence that connects the space of solutions of general relativity (GR) with that of Ricci-based gravity theories (RBGs) of the f(R, Q) type in the metric-affinc formulation, where Q = R(mu nu)R(mu nu). We focus on the case of scalar matter and show that when one considers a free massless scalar in the GR frame, important simplifications arise that allow one to establish the correspondence for arbitrary f (R, Q) Lagrangian. We particularize the analysis to a quadratic f (R, Q) theory and use the spherically symmetric, static solution of Jannis-Newman-Winicour as seed to generate new compact objects in our target theory. We find that two different types of solutions emerge, one representing naked singularities and another corresponding to asymmetric wormholes with bounded curvature scalars everywhere. The latter solutions, nonetheless, are geodesically incomplete.  
  Address [Magalhaes, Renan B.; Crispino, Luis C. B.] Univ Fed Para, Programa Posgrad Fis, BR-66075110 Belem, Para, Brazil, Email: renan.magalhaes@icen.ufpa.br;  
  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:000767103000006 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5171  
Permanent link to this record
 

 
Author Guerrero, M.; Olmo, G.J.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D. url  doi
openurl 
  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 (down) 105 Issue 8 Pages 084057 - 16pp  
  Keywords  
  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;  
  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:000810908800018 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5261  
Permanent link to this record
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