Title: Dark radiation and superheavy dark matter from black hole domination

Abstract

If even a relatively small number of black holes were created in the early universe, they will constitute an increasingly large fraction of the total energy density as space expands. It is thus well-motivated to consider scenarios in which the early universe included an era in which primordial black holes dominated the total energy density. Within this context, we consider Hawking radiation as a mechanism to produce both dark radiation and dark matter. If the early universe included a black hole dominated era, we find that Hawking radiation will produce dark radiation at a level $$\Delta N_{\rm eff} \sim 0.03-0.2$$ for each light and decoupled species of spin 0, 1/2, or 1. This range is well suited to relax the tension among late and early-time Hubble determinations, and is within the reach of upcoming CMB experiments. The dark matter could additionally originate as Hawking radiation in a black hole dominated early universe, although such dark matter candidates must be very heavy ($$m_{\rm DM} >10^{11}$$ GeV) if they are to avoid exceeding the measured abundance.

Authors:

Hooper, Dan ^[1]; Krnjaic, Gordan ^[2]; McDermott, Samuel D. ^[2]

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+ Show Author Affiliations

1. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Univ. of Chicago, IL (United States)
2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

Publication Date:

2019-08-01

Research Org.:

Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)

OSTI Identifier:

1545087

Report Number(s):

arXiv:1905.01301; FERMILAB-PUB-19-186-A
Journal ID: ISSN 1029-8479; 1733139

Grant/Contract Number:  

AC02-07CH11359

Resource Type:

Accepted Manuscript

Journal Name:

Journal of High Energy Physics (Online)

Additional Journal Information:

Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2019; Journal Issue: 8; Journal ID: ISSN 1029-8479

Publisher:

Springer Berlin

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Beyond Standard Model; Cosmology of Theories beyond the SM