Structure Formation after Reheating: Supermassive Primordial Black Holes and Fermi Ball Dark Matter

TL;DR

This paper explores how long-range forces during the radiation era can lead to the formation of supermassive primordial black holes or Fermi balls, potentially explaining dark matter and early universe structures.

Contribution

It provides a detailed model showing how fermion clustering and scalar interactions can produce supermassive PBHs or Fermi balls, offering new insights into dark matter and early structure formation.

Findings

Supermassive PBHs can seed high-redshift quasars.

Fermi balls can account for all cold dark matter.

Structure formation driven by Yukawa interactions during radiation era.

Abstract

In the presence of (relatively) long-range forces, structures can form even during the radiation dominated era, leading to compact objects, such as Fermi balls or primordial black holes (PBHs), which can account for all or part of dark matter. We present a detailed analysis of a model in which fermions are produced from the inflaton decay developing some particle-antiparticle asymmetry. These fermions undergo clustering and structure formation driven by a Yukawa interaction. The same interaction provides a cooling channel for the dark halos via scalar radiation, leading to rapid collapse and the formation of a compact object. We discuss the criteria for the formation of either PBHs and Fermi balls. In the PBH formation regime, supermassive PBHs can seed the active galactic nuclei or quasars found at high redshift. Alternatively, Fermi balls can account for all of the cold dark matter, while evading microlensing constraints.