MACHO Messages from the Big Bang

TL;DR

This paper models the present-day mass spectrum of dark matter compact objects, linking primordial black holes formed shortly after the Big Bang to current MACHO observations, and finds consistency with cosmological constraints.

Contribution

It introduces a model connecting primordial black hole formation shortly after the Big Bang to current dark matter MACHOs, aligning with astrophysical and cosmological data.

Findings

Predicted mass spectrum matches observational constraints.

Dark matter seeds likely formed around 10^-4 seconds after the Big Bang.

Total energy density at seed formation time is consistent with an Einstein-de Sitter universe.

Abstract

The present day mass spectrum for dark matter compact objects is calculated based on the assumption that a uniform population of PBHs was created at a definite red-shift, and that the mass spectrum evolved as a result of gravitational radiation. The predicted present day spectrum extends over many decades of mass and allows one to connect the abundance of MACHOs in the halo of our galaxy with the abundance of galactic seeds. Present day astrophysical constraints on the abundance of dark matter PBHs appear to be consistent with our predicted mass spectrum if it is assumed that the seeds for the present day dark matter MACHOs were created at a time ~ 10-4 second after the big bang. Remarkably the total cosmological energy density at this time obtained by extrapolating the sum of the present day dark matter and CMB energies backward in time is very close to the mass-energy density of an Einstein-de Sitter universe at the same time. This suggests that the radiation precursor to the CMB was created at about the same time as the seeds for the present day dark matter.