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Author |
Araujo Filho, A.A.; Hassanabadi, H.; Heidari, N.; Kriz, J.; Zare, S. |
![goto web page (via DOI) doi](img/doi.gif)
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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 ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
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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IOP Publishing Ltd |
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English |
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ISSN |
0264-9381 |
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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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Permanent link to this record |
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Author |
Araujo Filho, A.A. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Analysis of a regular black hole in Verlinde's gravity |
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 |
1 |
Pages |
015003 - 30pp |
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Keywords |
Verlinde's emergent gravity; dark matter; shadows; black hole |
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Abstract ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
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. |
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Address |
[Araujo Filho, A. A.] Univ Valencia, Ctr Mixto Univ Valencia, CSIC, Dept Fis Teor, Burjassot 46100, Valencia, Spain, Email: dilto@fisica.ufc.br |
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Publisher |
IOP Publishing Ltd |
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English |
Summary Language |
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ISSN |
0264-9381 |
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Notes |
WOS:001114102700001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5841 |
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Permanent link to this record |
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Author |
Heidari, N.; Hassanabadi, H.; Araujo Filho, A.A.; Kriz, J.; Zare, S.; Porfirio, P.J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Gravitational signatures of a non-commutative stable black hole |
Type |
Journal Article |
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Year |
2024 |
Publication |
Physics of the Dark Universe |
Abbreviated Journal |
Phys. Dark Universe |
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Volume |
43 |
Issue |
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Pages |
101382 - 13pp |
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Keywords |
Non-commutativity; Black hole; Shadows; Geodesics |
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Abstract ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
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. |
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Address |
[Heidari, N.; Hassanabadi, H.] Shahrood Univ Technol, Fac Phys, Shahrood, Iran, Email: heidari.n@gmail.com; |
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Publisher |
Elsevier |
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English |
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Notes |
WOS:001126934800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5857 |
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Permanent link to this record |
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Author |
Araujo Filho, A.A. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Thermodynamics of massless particles in curved spacetime |
Type |
Journal Article |
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Year |
2023 |
Publication |
International Journal of Geometric Methods in Modern Physics |
Abbreviated Journal |
Int. J. Geom. Methods Mod. Phys. |
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Volume |
12 |
Issue |
13 |
Pages |
2350226 - 40pp |
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Keywords |
Einstein-aether; thermodynamic properties; curved spacetime |
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Abstract ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
This work is devoted to study the behavior of massless particles within the context of curved spacetime. In essence, we investigate the consequences of the scale factor C(?) of the Friedmann-Robertson-Walker metric in the Einstein-aether formalism to study photon-like particles. To do so, we consider the system within the canonical ensemble formalism in order to derive the following thermodynamic state quantities: spectral radiance, Helmholtz free energy, pressure, entropy, mean energy and the heat capacity. Moreover, the correction to the Stefan-Boltzmann law and the equation of states are also provided. Particularly, we separate our study within three distinct cases, i.e. s = 0, p = 0; s = 1, p = 1; s = 2, p = 1. In the first one, the results are derived numerically. Nevertheless, for the rest of the cases, all the calculations are accomplished analytically showing explicitly the dependence of the scale factor C(?) and the Riemann zeta function ?(s). Furthermore, our analyses are accomplished in general taking into account three different regimes of temperature of the universe, i.e. the inflationary era (T = 10(13)GeV), the electroweak epoch (T = 10(3)GeV) and the cosmic microwave background (T = 10(-13)GeV). |
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Address |
[Araujo Filho, A. A.] Univ Fed Cearra UFC, Dept Fis, Campus Pici,CP 6030, BR-60455760 Fortaleza, CE, Brazil, Email: dilto@fisica.ufc.br |
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Publisher |
World Scientific Publ Co Pte Ltd |
Place of Publication |
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English |
Summary Language |
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ISSN |
0219-8878 |
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Notes |
WOS:001048378900001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5613 |
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Permanent link to this record |
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Author |
Araujo Filho, A.A.; Furtado, J.; Hassanabadi, H.; Reis, J.A.A.S. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Thermal analysis of photon-like particles in rainbow gravity |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physics of the Dark Universe |
Abbreviated Journal |
Phys. Dark Universe |
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Volume |
42 |
Issue |
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Pages |
101310 - 8pp |
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Keywords |
Rainbow gravity; Thermodynamics; Bounds |
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Abstract ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
This work is devoted to study the thermodynamic behavior of photon-like particles within the rainbow gravity formalism. To to do this, we chose two particular ansatzs to accomplish our calculations. First, we consider a dispersion relation which avoids UV divergences, getting a positive effective cosmological constant. We provide numerical analysis for the thermodynamic functions of the system and bounds are estimated. Furthermore, a phase transition is also expected for this model. Second, we consider a dispersion relation employed in the context of Gamma Ray Bursts. Remarkably, for this latter case, the thermodynamic properties are calculated in an analytical manner and they turn out to depend on the harmonic series Hn, gamma & UGamma; (z), polygamma & psi;n(z) and zeta Riemann functions & zeta;(z). |
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Address |
[Araujo Filho, A. A.] Univ Valencia, CSIC, Dept Fis Teor & IFIC, Ctr Mixto Univ Valencia, Valencia 46100, Spain, Email: dilto@fisica.ufc.br; |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier |
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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Notes |
WOS:001062674000001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5667 |
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Permanent link to this record |