Séminaire / Seminar GReCO |
| « Large black-hole scalar charges induced by cosmology in Horndeski theories » |
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Gilles Esposito-Farese |
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This talk summarizes my recent work arXiv:2504.07882 in
collaboration with E. Babichev (Orsay, France), I. Sawicki and L. Trombetta (Prague, Czechia). Contrary to general relativity, in which local and large-distance physics are almost decoupled, the present accelerated expansion of the Universe can drastically change the behavior of binary systems in scalar-tensor theories of gravity. We show that very large scalar charges are generated for black holes in specific models. However, their observable consequences are seriously reduced by two phenomena: the so-called Vainshtein screening, and the accretion of the scalar field by the black holes. In spite of such large scalar charges, they are found to be consistent with the LIGO/Virgo detections of coalescences. On the other hand, the future LISA mission should be able to improve by 16 orders of magnitude the present experimental constraint on the coefficient of the quintic Horndeski kinetic term. |
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lundi 30 juin 2025 - 11:00 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Pages web du séminaire / Seminar's webpage |