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Author |
Fernandez-Silvestre, D.; Foo, J.; Good, M.R.R. |
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Title |
On the duality of Schwarzschild-de Sitter spacetime and moving mirror |
Type |
Journal Article |
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Year |
2022 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal  |
Class. Quantum Gravity |
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Volume |
39 |
Issue |
5 |
Pages |
055006 - 18pp |
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Keywords |
QFT in curved spacetime; black holes; cosmological horizons; moving mirrors |
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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. |
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Address |
[Fernandez-Silvestre, Diego] Univ Valencia, CSIC, Dept Fis Teor, C Dr Moliner 50, Burjassot 46100, Spain, Email: diefer2@alumni.uv.es; |
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Publisher |
IOP Publishing Ltd |
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English |
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ISSN |
0264-9381 |
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Notes |
WOS:000754064600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5130 |
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Author |
Olmo, G.J.; Rosa, J.L.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D. |
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Title |
Shadows and photon rings of regular black holes and geonic horizonless compact objects |
Type |
Journal Article |
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Year |
2023 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
40 |
Issue |
17 |
Pages |
174002 - 37pp |
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Keywords |
black holes; compact objects; photon rings; shadows; metric-affine gravity; Born-Infeld gravity; regular solutions |
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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. |
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Address |
[Olmo, Gonzalo J.] Univ Valencia, Ctr Mixto Univ Valencia, Dept Fis Teor, CSIC, Burjassot 46100, Valencia, Spain, Email: drubiera@ucm.es |
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Publisher |
IOP Publishing Ltd |
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English |
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ISSN |
0264-9381 |
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Conference |
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Notes |
WOS:001043720300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5600 |
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Author |
Araujo Filho, A.A.; Hassanabadi, H.; Heidari, N.; Kriz, J.; Zare, S. |
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Title |
Gravitational traces of bumblebee gravity in metric-affine formalism |
Type |
Journal Article |
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Year |
2024 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
41 |
Issue |
5 |
Pages |
055003 - 21pp |
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Keywords |
bumblebee gravity; metric affine formalism; shadows |
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Abstract |
This work explores various manifestations of bumblebee gravity within the metric-affine formalism. We investigate the impact of the Lorentz violation parameter, denoted as X, on the modification of the Hawking temperature. Our calculations reveal that as X increases, the values of the Hawking temperature attenuate. To examine the behavior of massless scalar perturbations, specifically the quasinormal modes, we employ the Wentzel-Kramers-Brillouin method. The transmission and reflection coefficients are determined through our calculations. The outcomes indicate that a stronger Lorentz-violating parameter results in slower damping oscillations of gravitational waves. To comprehend the influence of the quasinormal spectrum on time-dependent scattering phenomena, we present a detailed analysis of scalar perturbations in the time-domain solution. Additionally, we conduct an investigation on shadows, revealing that larger values of X correspond to larger shadow radii. Furthermore, we constrain the magnitude of the shadow radii using the EHT horizon-scale image of SgrA* . Finally, we calculate both the time delay and the deflection angle. |
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Address |
[Araujo Filho, A. A.] Univ Valencia, CSIC, Dept Fis Teor, Ctr MIxto Univ Valencia, Burjassot 46100, Valencia, Spain, Email: dilto@fisica.ufc.br |
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Publisher |
IOP Publishing Ltd |
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English |
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ISSN |
0264-9381 |
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Conference |
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Notes |
WOS:001152994800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5925 |
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Author |
Navarro-Salas, J. |
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Title |
Black holes, conformal symmetry, and fundamental fields |
Type |
Journal Article |
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Year |
2024 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
41 |
Issue |
8 |
Pages |
085003 - 14pp |
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Keywords |
black holes; horizons; singularities; conformal symmetry; quantum fields; Standard Model |
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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. |
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Address |
[Navarro-Salas, Jose] Univ Valencia, Dept Fis Teor, IFIC, CSIC, E-46100 Burjassot, Valencia, Spain, Email: jnavarro@ific.uv.es |
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Corporate Author |
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Publisher |
IOP Publishing Ltd |
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 |
0264-9381 |
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Conference |
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Notes |
WOS:001187435100001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
6029 |
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Author |
David, M.; Borges, G.; Gomes, J.; Pina, J.; Campos, I.; Fernandez, E.; Lopez, A.; Orviz, P.; Cacheiro, J.L.; Fernandez, C.; Simon, A.; Fernandez, A. |
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Title |
Software Provision Process For EGI |
Type |
Journal Article |
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Year |
2012 |
Publication |
Computing and Informatics |
Abbreviated Journal |
Comput. Inform. |
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Volume |
31 |
Issue |
1 |
Pages |
135-148 |
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Keywords |
Grid infrastructures; Grid middleware; European Grid Infrastructure; European Middleware Initiative |
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Abstract |
The European Grid Initiative (EGI) provides a sustainable pan-European Grid computing infrastructure for e-Science based on a network of regional and national Grids. The middleware driving this production infrastructure is constantly adapted to the changing needs of the EGI Community by deploying new features and phasing out other features and components that are no longer needed. Unlike previous e-Infrastructure projects, EGI does not develop its own middleware solution, but instead sources the required components from Technology Providers and integrates them in the Unified Middleware Distribution (UMD). In order to guarantee a high quality and reliable operation of the infrastructure, all UMD software must undergo a release process that covers the definition of the functional, performance and quality requirements, the verification of those requirements and testing in production environments. |
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Address |
[David, Mario; Borges, Goncalo; Gomes, Jorge; Pina, Joao] Lab Instrumentacao & Fis Expt Particulas, Lisbon, Portugal, Email: david@lip.pt |
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Publisher |
Slovak Acad Sciences Inst Informatics |
Place of Publication |
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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 |
1335-9150 |
ISBN |
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Conference |
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Notes |
WOS:000303785400011 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1086 |
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