| Records |
| Author |
Maluf, R.V.; Mora-Perez, G.; Olmo, G.J.; Rubiera-Garcia, D. |
| Title |
Nonsingular, Lump-like, Scalar Compact Objects in (2+1)-Dimensional Einstein Gravity |
Type |
Journal Article |
| Year |
2024 |
Publication |
Universe |
Abbreviated Journal |
Universe |
| Volume |
10 |
Issue |
6 |
Pages |
258 - 13pp |
| Keywords |
Einstein gravity; compact objects; nonlinear scalar field |
| Abstract |
We study the space-time geometry generated by coupling a free scalar field with a noncanonical kinetic term to general relativity in (2+1) dimensions. After identifying a family of scalar Lagrangians that yield exact analytical solutions in static and circularly symmetric scenarios, we classify the various types of solutions and focus on a branch that yields asymptotically flat geometries. We show that the solutions within such a branch can be divided in two types, namely naked singularities and nonsingular objects without a center. In the latter, the energy density is localized around a maximum and vanishes only at infinity and at an inner boundary. This boundary has vanishing curvatures and cannot be reached by any time-like or null geodesic in finite affine time. This allows us to consistently interpret such solutions as nonsingular, lump-like, static compact scalar objects whose eventual extension to the (3+1)-dimensional context could provide structures of astrophysical interest. |
| Address |
[Maluf, Roberto V.; Olmo, Gonzalo J.] Univ Fed Ceara UFC, Dept Fis, Campus Pici, BR-60455760 Fortaleza, Ceara, Brazil, Email: r.v.maluf@fisica.ufc.br; |
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| Publisher |
Mdpi |
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| Language |
English |
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| Notes |
WOS:001256495600001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
6169 |
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| Author |
Balbinot, R.; Fabbri, A. |
| Title |
The Unruh Vacuum and the “In-Vacuum” in Reissner-Nordström Spacetime |
Type |
Journal Article |
| Year |
2024 |
Publication |
Universe |
Abbreviated Journal |
Universe |
| Volume |
10 |
Issue |
1 |
Pages |
18 - 14pp |
| Keywords |
Hawking radiation; Unruh vacuum; Reissner-Nordstrom black holes |
| Abstract |
The Unruh vacuum is widely used as a quantum state to describe black hole evaporation since, near the horizon, it reproduces the physical state of a quantum field, the so-called “in-vacuum”, in the case where a black hole is formed by gravitational collapse. We examine the relation between these two quantum states in the background spacetime of a Reissner-Nordstrom black hole (both extremal and not), highlighting the similarities and striking differences. |
| Address |
[Balbinot, Roberto] Univ Bologna, Dipartimento Fis, Via Irnerio 46, I-40126 Bologna, Italy, Email: roberto.balbinot@unibo.it; |
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Mdpi |
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| Language |
English |
Summary Language |
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Conference |
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| Notes |
WOS:001151025300001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
5914 |
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| Author |
Araujo Filho, A.A.; Jusufi, K.; Cuadros-Melgar, B.; Leon, G. |
| Title |
Dark matter signatures of black holes with Yukawa potential |
Type |
Journal Article |
| Year |
2024 |
Publication |
Physics of the Dark Universe |
Abbreviated Journal |
Phys. Dark Universe |
| Volume |
44 |
Issue |
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Pages |
101500 - 20pp |
| Keywords |
Quantum-corrected Yukawa-like gravitational potential; Dark matter; Quasinormal frequencies; Black Holes shadows |
| Abstract |
This study uses a nonsingular Yukawa-modified potential to obtain a static and spherically symmetric black hole solution with a cosmological constant. Such Yukawa-like corrections are encoded in two parameters, alpha and lambda, that modify Newton's law of gravity in large distances, and a deformation parameter l(0), which plays an essential role in short distances. The most significant effect is encoded in alpha, which modifies the total black hole mass with an extra mass proportional to alpha M, mimicking the dark matter effects at large distances from the black hole. On the other hand, the effect due to lambda is small for astrophysical values. We scrutinize the quasinormal frequencies and shadows associated with a spherically symmetric black hole and the thermodynamical behavior influenced by the Yukawa potential. In particular, the thermodynamics of this black hole displays a rich behavior, including possible phase transitions. We use the WKB method to probe the quasinormal modes of massless scalar, electromagnetic, and gravitational field perturbations. In order to check the influence of the parameters on the shadow radius, we consider astrophysical data to determine their values, incorporating information on an optically thin radiating and infalling gas surrounding a black hole to model the black hole shadow image. In particular, we consider Sgr A* black hole as an example and we find that its shadow radius changes by order of 10(-9), meaning that the shadow radius of a black hole with Yukawa potential practically gives rise to the same result encountered in the Schwarzschild black hole. Also, in the eikonal regime, using astrophysical data for Yukawa parameters, we show that the value of the real part of the QNMs frequencies changes by 10(-18). Such Yukawa-like corrections are, therefore, difficult to measure by observations of gravitational waves using the current technology. |
| Address |
[Filhoa, A. A. Araujo] Univ Valencia, Ctr Mixto Univ Valencia, Dept Fis Teor, CSIC, Burjassot 46100, Valencia, Spain, Email: dilto@fisica.ufc.br; |
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| Publisher |
Elsevier |
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English |
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Expedition |
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Conference |
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| Notes |
WOS:001287415400001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
6226 |
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| Author |
Araujo Filho, A.A.; Furtado, J.; Hassanabadi, H.; Reis, J.A.A.S. |
| Title |
Thermal analysis of photon-like particles in rainbow gravity |
Type |
Journal Article |
| Year |
2023 |
Publication |
Physics of the Dark Universe |
Abbreviated Journal |
Phys. Dark Universe |
| Volume |
42 |
Issue |
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Pages |
101310 - 8pp |
| Keywords |
Rainbow gravity; Thermodynamics; Bounds |
| Abstract |
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). |
| 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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| Publisher |
Elsevier |
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English |
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Expedition |
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Conference |
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| Notes |
WOS:001062674000001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
5667 |
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| Author |
Heidari, N.; Hassanabadi, H.; Araujo Filho, A.A.; Kriz, J.; Zare, S.; Porfirio, P.J. |
| 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 |
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Pages |
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; |
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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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ISBN |
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Expedition |
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Conference |
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| Notes |
WOS:001126934800001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
5857 |
| Permanent link to this record |
