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Author |
Creminelli, P.; Loayza, N.; Serra, F.; Trincherini, E.; Trombetta, L.G. |
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Title  |
Hairy black-holes in shift-symmetric theories |
Type |
Journal Article |
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Year |
2020 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
08 |
Issue |
8 |
Pages |
045 - 24pp |
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Keywords |
Black Holes; Classical Theories of Gravity |
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Abstract |
Scalar hair of black holes in theories with a shift symmetry are constrained by the no-hair theorem of Hui and Nicolis, assuming spherical symmetry, time-independence of the scalar field and asymptotic flatness. The most studied counterexample is a linear coupling of the scalar with the Gauss-Bonnet invariant. However, in this case the norm of the shift-symmetry current J(2) diverges at the horizon casting doubts on whether the solution is physically sound. We show that this is not an issue since J(2) is not a scalar quantity, since J(mu) is not a diffinvariant current in the presence of Gauss-Bonnet. The same theory can be written in Horndeski form with a non-analytic function G(5)similar to log X . In this case the shift-symmetry current is diff-invariant, but contains powers of X in the denominator, so that its divergence at the horizon is again immaterial. We confirm that other hairy solutions in the presence of non-analytic Horndeski functions are pathological, featuring divergences of physical quantities as soon as one departs from time-independence and spherical symmetry. We generalise the no-hair theorem to Beyond Horndeski and DHOST theories, showing that the coupling with Gauss-Bonnet is necessary to have hair. |
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Address |
[Creminelli, Paolo] Abdus Salaam Int Ctr Theoret Phys, Int Ctr Theoret Phys, Str Costiera 11, I-34151 Trieste, Italy, Email: creminel@ictp.it; |
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Publisher |
Springer |
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English |
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ISSN |
1029-8479 |
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Notes |
WOS:000562728200001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4515 |
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Author |
Heidari, N.; Hassanabadi, H.; Araujo Filho, A.A.; Kriz, J.; Zare, S.; Porfirio, P.J. |
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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 |
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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Author |
Galli, P.; Ortin, T.; Perz, J.; Shahbazi, C.S. |
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Title |
From supersymmetric to non-supersymmetric black holes |
Type |
Journal Article |
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Year |
2012 |
Publication |
Fortschritte der Physik-Progress of Physics |
Abbreviated Journal |
Fortschritte Phys.-Prog. Phys. |
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Volume |
60 |
Issue |
9-10 |
Pages |
1026-1029 |
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Keywords |
Black holes; supergravity |
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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]. |
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Address |
[Ortin, Tomas; Perz, Jan; Shahbazi, C. S.] Inst Fis Teor UAM CSIC, Madrid 28049, Spain, Email: Pietro.Galli@ific.uv.es; |
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Wiley-V C H Verlag Gmbh |
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English |
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ISSN |
0015-8208 |
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Conference |
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Notes |
WOS:000308301500012 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1151 |
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Author |
Galli, P.; Goldstein, K.; Katmadas, S.; Perz, J. |
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Title |
First-order flows and stabilisation equations for non-BPS extremal black holes |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
06 |
Issue |
6 |
Pages |
070 - 28pp |
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Keywords |
Black Holes in String Theory; Supergravity Models |
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Abstract |
We derive a generalised form of flow equations for extremal static and rotating non-BPS black holes in four-dimensional ungauged N = 2 supergravity coupled to vector multiplets. For particular charge vectors, we give stabilisation equations for the scalars, analogous to the BPS case, describing full known solutions. Based on this, we propose a generic ansatz for the stabilisation equations, which surprisingly includes ratios of harmonic functions. |
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Address |
[Galli, P] Univ Valencia, Dept Fis Teor, E-46100 Burjassot, Valencia, Spain, Email: Pietro.Galli@ific.uv.es |
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Publisher |
Springer |
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Language |
English |
Summary Language |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1126-6708 |
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Conference |
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Notes |
WOS:000293136500070 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
746 |
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Author |
Agius, D.; Essig, R.; Gaggero, D.; Scarcella, F.; Suczewski, G.; Valli, M. |
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Title |
Feedback in the dark: a critical examination of CMB bounds on primordial black holes |
Type |
Journal Article |
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Year |
2024 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
003 - 36pp |
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Keywords |
accretion; cosmological parameters from CMBR; dark matter theory; primordial black holes |
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Abstract |
If present in the early universe, primordial black holes (PBHs) would have accreted matter and emitted high-energy photons, altering the statistical properties of the Cosmic Microwave Background (CMB). This mechanism has been used to constrain the fraction of dark matter that is in the form of PBHs to be much smaller than unity for PBH masses well above one solar mass. Moreover, the presence of dense dark matter mini -halos around the PBHs has been used to set even more stringent constraints, as these would boost the accretion rates. In this work, we critically revisit CMB constraints on PBHs taking into account the role of the local ionization of the gas around them. We discuss how the local increase in temperature around PBHs can prevent the dark matter mini -halos from strongly enhancing the accretion process, in some cases significantly weakening previously derived CMB constraints. We explore in detail the key ingredients of the CMB bound and derive a conservative limit on the cosmological abundance of massive PBHs. |
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Address |
[Agius, Dominic] Univ Valencia, CSIC, Inst Fis Corpuscular, C Catedrat Jose Beltran 2, E-46980 Paterna, Spain, Email: dominic.agius@ific.uv.es; |
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Publisher |
IOP Publishing Ltd |
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 |
1475-7516 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001262242300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6187 |
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