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Author Villanueva-Domingo, P.; Mena, O.; Palomares-Ruiz, S. url  doi
openurl 
  Title A Brief Review on Primordial Black Holes as Dark Matter Type Journal Article
  Year 2021 Publication Frontiers in Astronomy and Space Sciences Abbreviated Journal Front. Astron. Space Sci.  
  Volume 8 Issue Pages (down) 681084 - 10pp  
  Keywords primordial black holes; dark matter; cosmology; accretion; 21 cm cosmology; gravitational waves; cosmic microwave background; microlensing  
  Abstract Primordial black holes (PBHs) represent a natural candidate for one of the components of the dark matter (DM) in the Universe. In this review, we shall discuss the basics of their formation, abundance and signatures. Some of their characteristic signals are examined, such as the emission of particles due to Hawking evaporation and the accretion of the surrounding matter, effects which could leave an impact in the evolution of the Universe and the formation of structures. The most relevant probes capable of constraining their masses and population are discussed.  
  Address [Villanueva-Domingo, Pablo; Mena, Olga; Palomares-Ruiz, Sergio] CSIC Univ Valencia, Inst Fis Corpuscular IFIC, Paterna, Spain, Email: pablo.villanueva.domingo@gmail.com  
  Corporate Author Thesis  
  Publisher Frontiers Media Sa Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2296-987x ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000660081700001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4852  
Permanent link to this record
 

 
Author Olmo, G.J.; Rosa, J.L.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D. url  doi
openurl 
  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 (down) 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 Araujo Filho, A.A.; Zare, S.; Porffrio, P.J.; Kriz, J.; Hassanabadi, H. url  doi
openurl 
  Title Thermodynamics and evaporation of a modified Schwarzschild black hole in a non-commutative gauge theory Type Journal Article
  Year 2023 Publication Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 838 Issue Pages (down) 137744 - 9pp  
  Keywords Thermodynamic properties; Black hole; Non-commutative gauge theory; Evaporation process  
  Abstract In this work, we study the thermodynamic properties on a non-commutative background via gravitational gauge field potentials. This procedure is accomplished after contracting de Sitter (dS) group, SO(4, 1), with the Poincare group, ISO(3, 1). Particularly, we focus on a static spherically symmetric black hole. In this manner, we calculate the modified Hawking temperature and the other deformed thermal state quantities, namely, entropy, heat capacity, Helmholtz free energy and pressure. Finally, we also investigate the black hole evaporation process in such a context.  
  Address [Araujo Filho, A. A.] Univ Valencia, Dept Fis Teor, Burjassot 46100, Valencia, Spain, Email: dilto@fisica.ufc.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 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000935398000001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5483  
Permanent link to this record
 

 
Author Olmo, G.J.; Rubiera-Garcia, D.; Sanchez-Puente, A. url  doi
openurl 
  Title Impact of curvature divergences on physical observers in a wormhole space-time with horizons Type Journal Article
  Year 2016 Publication Classical and Quantum Gravity Abbreviated Journal Class. Quantum Gravity  
  Volume 33 Issue 11 Pages (down) 115007 - 12pp  
  Keywords Singularities; black holes; metric-affine geometry  
  Abstract The impact of curvature divergences on physical observers in a black hole space-time, which, nonetheless, is geodesically complete is investigated. This space-time is an exact solution of certain extensions of general relativity coupled to Maxwell's electrodynamics and, roughly speaking, consists of two Reissner-Nordstrom (or Schwarzschild or Minkowski) geometries connected by a spherical wormhole near the center. We find that, despite the existence of infinite tidal forces, causal contact is never lost among the elements making up the observer. This suggests that curvature divergences may not be as pathological as traditionally thought.  
  Address [Olmo, Gonzalo J.; Sanchez-Puente, A.] Univ Valencia, CSIC, Ctr Mixto, Dept Fis Teor, E-46100 Valencia, Spain, Email: gonzalo.olmo@csic.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:000377442000010 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2728  
Permanent link to this record
 

 
Author Heidari, N.; Hassanabadi, H.; Araujo Filho, A.A.; Kriz, J.; Zare, S.; Porfirio, P.J. url  doi
openurl 
  Title Gravitational signatures of a non-commutative stable black hole Type Journal Article
  Year 2024 Publication Physics of the Dark Universe Abbreviated Journal Phys. Dark Universe  
  Volume 43 Issue Pages (down) 101382 - 13pp  
  Keywords Non-commutativity; Black hole; Shadows; Geodesics  
  Abstract This work investigates several key aspects of a non-commutative theory with mass deformation. We calculate thermodynamic properties of the system and compare our results with recent literature. We examine the quasinormal modes of massless scalar perturbations using two approaches: the WKB approximation and the Poschl-Teller fitting method. Our results indicate that stronger non-commutative parameters lead to slower damping oscillations of gravitational waves and higher partial absorption cross sections. Furthermore, we study the geodesics of massless and massive particles, highlighting that the non-commutative parameter (R) significantly impacts the paths of light and event horizons. Also, we calculate the shadows, which show that larger values of (R) correspond to larger shadow radii, and provide some constraints on (R) applying the observation of Sgr A* from the Event Horizon Telescope. Finally, we explore the deflection angle in this context.  
  Address [Heidari, N.; Hassanabadi, H.] Shahrood Univ Technol, Fac Phys, Shahrood, Iran, Email: heidari.n@gmail.com;  
  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 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001126934800001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5857  
Permanent link to this record
 

 
Author Navarro-Salas, J. url  doi
openurl 
  Title Black holes, conformal symmetry, and fundamental fields Type Journal Article
  Year 2024 Publication Classical and Quantum Gravity Abbreviated Journal Class. Quantum Gravity  
  Volume 41 Issue 8 Pages (down) 085003 - 14pp  
  Keywords black holes; horizons; singularities; conformal symmetry; quantum fields; Standard Model  
  Abstract Cosmic censorship protects the outside world from black hole singularities and paves the way for assigning entropy to gravity at the event horizons. We point out a tension between cosmic censorship and the quantum backreacted geometry of Schwarzschild black holes, induced by vacuum polarization and driven by the conformal anomaly. A similar tension appears for the Weyl curvature hypothesis at the Big Bang singularity. We argue that the requirement of exact conformal symmetry resolves both conflicts and has major implications for constraining the set of fundamental constituents of the Standard Model.  
  Address [Navarro-Salas, Jose] Univ Valencia, Dept Fis Teor, IFIC, CSIC, E-46100 Burjassot, Valencia, Spain, Email: jnavarro@ific.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 0264-9381 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001187435100001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 6029  
Permanent link to this record
 

 
Author Olmo, G.J.; Rubiera-Garcia, D.; Sanchez-Puente, A. url  doi
openurl 
  Title Accelerated observers and the notion of singular spacetime Type Journal Article
  Year 2018 Publication Classical and Quantum Gravity Abbreviated Journal Class. Quantum Gravity  
  Volume 35 Issue 5 Pages (down) 055010 - 18pp  
  Keywords general relativity; geodesic behaviour; black holes; spacetime singularities; modified theories of gravity  
  Abstract Geodesic completeness is typically regarded as a basic criterion to determine whether a given spacetime is regular or singular. However, the principle of general covariance does not privilege any family of observers over the others and, therefore, observers with arbitrary motions should be able to provide a complete physical description of the world. This suggests that in a regular spacetime, all physically acceptable observers should have complete paths. In this work we explore this idea by studying the motion of accelerated observers in spherically symmetric spacetimes and illustrate it by considering two geodesically complete black hole spacetimes recently described in the literature. We show that for bound and locally unbound accelerations, the paths of accelerated test particles are complete, providing further support to the regularity of such spacetimes.  
  Address [Olmo, Gonzalo J.; Sanchez-Puente, Antonio] Univ Valencia, Dept Fis Teor, CSIC, Ctr Mixto, E-46100 Valencia, Spain, Email: gonzalo.olmo@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 0264-9381 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000424042100001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3473  
Permanent link to this record
 

 
Author Fernandez-Silvestre, D.; Foo, J.; Good, M.R.R. url  doi
openurl 
  Title On the duality of Schwarzschild-de Sitter spacetime and moving mirror Type Journal Article
  Year 2022 Publication Classical and Quantum Gravity Abbreviated Journal Class. Quantum Gravity  
  Volume 39 Issue 5 Pages (down) 055006 - 18pp  
  Keywords QFT in curved spacetime; black holes; cosmological horizons; moving mirrors  
  Abstract The Schwarzschild-de Sitter (SdS) metric is the simplest spacetime solution in general relativity with both a black hole event horizon and a cosmological event horizon. Since the Schwarzschild metric is the most simple solution of Einstein's equations with spherical symmetry and the de Sitter metric is the most simple solution of Einstein's equations with a positive cosmological constant, the combination in the SdS metric defines an appropriate background geometry for semi-classical investigation of Hawking radiation with respect to past and future horizons. Generally, the black hole temperature is larger than that of the cosmological horizon, so there is heat flow from the smaller black hole horizon to the larger cosmological horizon, despite questions concerning the definition of the relative temperature of the black hole without a measurement by an observer sitting in an asymptotically flat spacetime. Here we investigate the accelerating boundary correspondence of the radiation in SdS spacetime without such a problem. We have solved for the boundary dynamics, energy flux and asymptotic particle spectrum. The distribution of particles is globally non-thermal while asymptotically the radiation reaches equilibrium.  
  Address [Fernandez-Silvestre, Diego] Univ Valencia, CSIC, Dept Fis Teor, C Dr Moliner 50, Burjassot 46100, Spain, Email: diefer2@alumni.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 0264-9381 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000754064600001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5130  
Permanent link to this record
 

 
Author Araujo Filho, A.A. url  doi
openurl 
  Title Analysis of a regular black hole in Verlinde's gravity Type Journal Article
  Year 2024 Publication Classical and Quantum Gravity Abbreviated Journal Class. Quantum Gravity  
  Volume 41 Issue 1 Pages (down) 015003 - 30pp  
  Keywords Verlinde's emergent gravity; dark matter; shadows; black hole  
  Abstract This work focuses on the examination of a regular black hole within Verlinde's emergent gravity, specifically investigating the Hayward-like (modified) solution. The study reveals the existence of three horizons under certain conditions, i.e. an event horizon and two Cauchy horizons. Our results indicate regions which phase transitions occur based on the analysis of heat capacity and Hawking temperature. To compute the latter quantity, we utilize three distinct methods: the surface gravity approach, Hawking radiation, and the application of the first law of thermodynamics. In the case of the latter approach, it is imperative to introduce a correction to ensure the preservation of the Bekenstein-Hawking area law. Geodesic trajectories and critical orbits (photon spheres) are calculated, highlighting the presence of three light rings. Additionally, we investigate the black hole shadows. Furthermore, the quasinormal modes are explored using third- and sixth-order Wentzel-Kramers-Brillouin approximations. In particular, we observe stable and unstable oscillations for certain frequencies. Finally, in order to comprehend the phenomena of time-dependent scattering in this scenario, we provide an investigation of the time-domain solution.  
  Address [Araujo Filho, A. A.] Univ Valencia, Ctr Mixto Univ Valencia, CSIC, Dept Fis Teor, Burjassot 46100, Valencia, Spain, Email: dilto@fisica.ufc.br  
  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:001114102700001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5841  
Permanent link to this record
 

 
Author Galli, P.; Ortin, T.; Perz, J.; Shahbazi, C.S. doi  openurl
  Title From supersymmetric to non-supersymmetric black holes Type Journal Article
  Year 2012 Publication Fortschritte der Physik-Progress of Physics Abbreviated Journal Fortschritte Phys.-Prog. Phys.  
  Volume 60 Issue 9-10 Pages (down) 1026-1029  
  Keywords Black holes; supergravity  
  Abstract Methods similar to those used for obtaining supersymmetric black hole solutions can be employed to find also non-supersymmetric solutions. We briefly review some of them, with the emphasis on the non-extremal deformation ansatz of [1].  
  Address [Ortin, Tomas; Perz, Jan; Shahbazi, C. S.] Inst Fis Teor UAM CSIC, Madrid 28049, Spain, Email: Pietro.Galli@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Wiley-V C H Verlag Gmbh Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0015-8208 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000308301500012 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 1151  
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