The 21cm Absorption Line and Axion Quark Nugget Dark Matter Model

TL;DR

This paper proposes that quark nugget dark matter could explain the unexpectedly strong 21 cm absorption signal observed by EDGES, by affecting early universe thermal emissions.

Contribution

It introduces a novel dark matter model involving quark nuggets that can account for the EDGES 21 cm anomaly and possibly the ARCADE2 GHz excess.

Findings

Quark nugget dark matter can produce additional thermal emission at early times.

The model explains the stronger 21 cm absorption observed by EDGES.

Potential contribution to the GHz excess observed by ARCADE2.

Abstract

We argue that dark matter in the form of macroscopically large nuggets of standard model quarks and antiquarks can help to alleviate the tension between standard model cosmology and the recent EDGES observation of a stronger than anticipated 21 cm absorption feature. The effect occurs as a result of the thermal emission from quark nugget dark matter at early times and at energies well below the peak of the CMB. Similar radiation at early times may also contribute a fraction of the GHz range excess observed by ARCADE2.