Light primordial exotic compact objects as all dark matter

Martti Raidal,Hardi Veermäe,Ville Vaskonen,Sergey Solodukhin

doi:10.1103/physrevd.97.123520

Abstract

The radiation emitted by horizonless exotic compact objects (ECOs), such as wormholes, 2-2-holes, fuzzballs, gravastars, boson stars, collapsed polymers, superspinars etc., is expected to be strongly suppressed when compared to the radiation of black holes. If large primordial curvature fluctuations collapse into such objects instead of black holes, they do not evaporate or evaporate much slower than black holes and could thus constitute all of the dark matter with masses below $M < 10^{-16}M_\odot.$ We reevaluate the relevant experimental constraints for light ECOs in this mass range and show that very large new parameter space down to ECO masses $M\sim 10\,{\rm TeV}$ opens up for light primordial dark matter. A new dedicated experimental program is needed to test this mass range of primordial dark matter.

Highlights

According to the original idea by Hawking [1], large primordial fluctuation could collapse into primordial black holes (PBHs) when entering into the horizon during radiation dominated era
We find that such modifications can open a new, wide mass window in which all the dark matter (DM) consists of light primordial exotic compact objects (ECOs)
All of the DM can be in the form of objects that radiate less effectively than the classical PBHs, either in ECOs or, for small values of α, in PBHs where Hawking radiation is modified by unknown quantum gravity effects

Summary

Introduction

According to the original idea by Hawking [1], large primordial fluctuation could collapse into primordial black holes (PBHs) when entering into the horizon during radiation dominated era. Combining all existing experimental constraints [8], no PBHs with masses smaller than M ≲ 10−16 M⊙ ∼ 1017 g should exist today in any relevant cosmological abundance. This limit, in the mass range 10−16 ≲ M=M⊙ ≲ 105, the lensing limits [10,11,12,13], various astrophysical and cosmic microwave background constraints [14,15,16,17,18,19] as well as the PBH merger rate estimates [20,21] imply that the PBHs cannot be the dominant DM component [22]

Objectives

Results

Conclusion