Primordial Black Holes from Sound Speed Resonance during Inflation

Yi-Fu Cai, Xi Tong, Dong-Gang Wang, and Sheng-Feng Yan

Phys. Rev. Lett. 121, 081306 – Published 24 August 2018

Abstract

We report on a novel phenomenon of the resonance effect of primordial density perturbations arisen from a sound speed parameter with an oscillatory behavior, which can generically lead to the formation of primordial black holes in the early Universe. For a general inflaton field, it can seed primordial density fluctuations, and their propagation is governed by a parameter of sound speed square. Once, if this parameter achieves an oscillatory feature for a while during inflation, a significant nonperturbative resonance effect on the inflaton field fluctuations takes place around a critical length scale, which results in significant peaks in the primordial power spectrum. By virtue of this robust mechanism, primordial black holes with specific mass function can be produced with a sufficient abundance for dark matter in sizable parameter ranges.

Received 13 May 2018
Revised 31 July 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.081306

Physics Subject Headings (PhySH)

Cosmology Dark matter Evolution of the Universe Inflation

Classical black holes

Particles & FieldsGravitation, Cosmology & Astrophysics

Authors & Affiliations

Yi-Fu Cai^1,2,*, Xi Tong^1,2,3,†, Dong-Gang Wang^4,5,‡, and Sheng-Feng Yan^1,2,§

¹CAS Key Laboratory for Researches in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026, China
²School of Astronomy and Space Science, University of Science and Technology of China, Hefei, Anhui 230026, China
³Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
⁴Lorentz Institute for Theoretical Physics, Leiden University, 2333 CA Leiden, Netherlands
⁵Leiden Observatory, Leiden University, 2300 RA Leiden, Netherlands

^*yifucai@ustc.edu.cn
^†tx123@mail.ustc.edu.cn
^‡wdgang@strw.leidenuniv.nl
^§sfyan22@mail.ustc.edu.cn

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Vol. 121, Iss. 8 — 24 August 2018

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