Coupled DM heating in SCDEW cosmologies

TL;DR

This paper models early non-linear growth of coupled dark matter fluctuations in SCDEW cosmologies, showing that virialized structures can evaporate and influence larger scale dynamics.

Contribution

It introduces a top-hat density enhancement model to study early non-linear stages and the evaporation of virialized dark matter structures in SCDEW cosmologies.

Findings

Early non-linear dark matter fluctuations can reach virial balance.

Virialized lumps undergo evaporation, affecting subsequent structure formation.

Processed dark matter particles retain momentum influencing larger scales.

Abstract

Strongly Coupled Dark Energy plus Warm dark matter (SCDEW) cosmologies admit the stationary presence of $\sim 1\, \%$ of coupled-DM and DE, since inflationary reheating. Coupled-DM fluctuations therefore grow up to non-linearity even in the early radiative expansion. Such early non-linear stages are modelized here through the evolution of a top-hat density enhancement, reaching an early virial balance when the coupled-DM density contrast is just 25-26 and DM density enhancement is $ \sim 10\, \%$ of total density. During the time needed to settle in virial equilibium, the virial balance conditions however continue to modify, so that "virialized" lumps undergo a complete evaporation. Here we outline that DM particles processed by overdentities preserve a fraction of their virial momentum. Although fully non-relativistic, the resulting velocities (moderately) affect the fluctuation dynamics over greater scales, entering the horizon later on.