The joint evolution of baryons and dark matter haloes

TL;DR

This study investigates how baryons and dark matter halos co-evolve, revealing that galaxy formation history, feedback processes, and assembly mode significantly influence the distribution and concentration of dark matter within halos.

Contribution

It demonstrates the complex interplay between baryonic physics and dark matter halo evolution, emphasizing the role of assembly history and feedback in shaping galaxy structures.

Findings

Baryons increase halo concentration depending on assembly history.

Stronger supernova feedback leads to less massive, more disrupted satellites.

Inner halo angular momentum and stellar migration influence dark matter distribution.

Abstract

We have studied the dark matter (DM) distribution in a approx 10^12 h^-1 M_sun mass halo extracted from a simulation consistent with the concordance cosmology, where the physics regulating the transformation of gas into stars was allowed to change producing galaxies with different morphologies. The presence of baryons produces the concentration of the DM halo with respect to its corresponding dissipationless run, but we found that this response does not only depend on the amount of baryons gathered in the central region but also on the way they have been assembled. DM and baryons affect each other in a complex way so the formation history of a galaxy plays an important role on its final total mass distribution. Supernova (SN) feedback regulates the star formation and triggers galactic outflows not only in the central galaxy but also in its satellites. Our results suggest that, as the effects of SN feedback get stronger, satellites get less massive and can even be more easily disrupted by dynamical friction, transferring less angular momentum. We found indications that this angular momentum could be acquired not only by the outer part of the DM halo but also by the inner ones and by the stellar component in the central galaxy. The latter effect produces stellar migration which contributes to change the inner potential well, probably working against further DM contraction. As a consequence of the action of these processes, when the halo hosts a galaxy with an important disc structure formed by smooth gas accretion, it is more concentrated than when it hosts a spheroidal system which experienced more massive mergers and interactions. (abridged)