Noncanonical inflation and primordial black holes production
Abstract
We study a mechanism for the amplification of the inflationary scalar perturbation when the inflaton field action is noncanonical, i.e. the inflaton kinetic term has a nonstandard form. For such a case the speed of sound of the perturbations generated during inflation is less than one and in general changes with time. Furthermore in such models, even when the scalar field potential is negligible, diverse inflationary attractors may exist. The possible effects of a speed of sound approaching zero during some stage of inflation may lead to a large amplification for the amplitude of the scalar spectrum which, on horizon reentry during the radiation dominated phase, can collapse and form primordial black holes (PBH) of a mass M_{BH} ∼10^{15}M_{☉} which may constitute a large fraction of the total Dark Matter (DM) today.
 Publication:

Physics Letters B
 Pub Date:
 April 2019
 DOI:
 10.1016/j.physletb.2019.02.036
 arXiv:
 arXiv:1812.02547
 Bibcode:
 2019PhLB..791..201K
 Keywords:

 Primordial black holes;
 Inflation;
 Cosmological perturbations;
 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 14 pages, 1 figure. References added. Final version published on PLB