Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Série APC-TH
Domaines gr-qc
Date Mardi 21 Mai 2019
Heure 14:00
Institut APC
Salle 646A - Mondrian
Nom de l'orateur Ando
Prenom de l'orateur Kenta
Addresse email de l'orateur
Institution de l'orateur University of Tokyo, Kashiwa & Kavli IPMU
Titre Primordial black holes and the inflationary universe
Résumé The interest in primordial black holes (PBHs) has recently risen up again after the discovery of around 30 solar mass black holes through the LIGO/Virgo gravitational wave events. PBHs are black holes produced by gravitational collapse of the over-dense region in the early universe. An attractive origin of the overdensity is primordial perturbations generated during inflation. In this talk, I will first explain the relation between the power spectrum of the perturbations predicted by inflation models and the estimated PBH abundance. This relation has various theoretical uncertainties including the choice of the window function (https://arxiv.org/abs/1802.06393). Next, as a concrete model, I will briefly introduce the so-called axion-like curvaton model, where the phase direction of a complex scalar field different from inflaton is responsible for small-scale perturbations ( https://arxiv.org/abs/1711.08956, https://arxiv.org/abs/1805.07757). We found that PBHs produced in this model can successfully reproduce the LIGO/Virgo gravitational wave events. Finally, I would like to discuss the case where a single-field inflaton potential has an inflection point. There, a slow-roll violation enhances quantum fluctuation. We should use stochastic inflation formalism since the quantum back reaction could become significant. However, stochastic inflation beyond slow-roll regimes is nontrivial and worth investigating by itself. I will show a numerical result obtained so far under a simplified setup.
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