Strongly Coupled Cosmologies

TL;DR

Strongly Coupled cosmologies propose a high coupling between dark energy and cold dark matter, with an uncoupled warm component, matching standard cosmology on large scales while addressing small-scale structure issues.

Contribution

This paper introduces strongly coupled cosmologies with a large DE-CDM coupling and a warm DM component, offering new insights into structure formation and early universe phenomena.

Findings

Agreement with LCDM on supergalactic scales

Eases problems of MW satellites and dwarf galaxy cores

Provides new perspectives on early black hole formation

Abstract

Models including an energy transfer from CDM to DE are widely considered in the literature, namely to allow DE a significant high-z density. Strongly Coupled cosmologies assume a much larger coupling between DE and CDM, together with the presence of an uncoupled warm DM component, as the role of CDM is mostly restricted to radiative eras. This allows us to preserve small scale fluctuations even if the warm particle, possibly a sterile neutrino, is quite light, O(100 eV). Linear theory and numerical simulations show that these cosmologies agree with LCDM on supergalactic scales; e.g., CMB spectra are substantially identical. Simultaneously, simulations show that they significantly ease problems related to the properties of MW satellites and cores in dwarfs. SC cosmologies also open new perspectives on early black hole formation, and possibly lead towards unificating DE and inflationary scalar fields.