Dynamics of the response of dark matter halo to galaxy evolution in IllustrisTNG

TL;DR

This study investigates how dark matter halos dynamically respond to galaxy evolution processes using IllustrisTNG simulations, revealing the influence of star formation and feedback on halo relaxation over cosmic time.

Contribution

It demonstrates the applicability of a radially-dependent relaxation model at high redshift and links halo relaxation behavior to galaxy star formation and feedback mechanisms.

Findings

Star formation activity affects halo relaxation immediately in inner regions.

Outer halo relaxation shows a delay of 2-3 Gyr related to star formation.

Feedback winds correlate strongly with halo relaxation changes.

Abstract

We present the dynamical evolution of the dark matter's relaxation response to galaxies and their connection to the astrophysical properties as simulated in the IllustrisTNG suite of cosmological hydrodynamical simulations. Our results show that the radially-dependent linear relaxation relation model from our previous work is applicable at least from redshift $z=5$. We focus on the offset parameter $q_0$, which characterizes the relaxation of dark matter shells without changing the enclosed mass. We perform multiple time-series analyses to determine the possible causal connections between the relaxation mechanism and astrophysical processes such as star formation and associated feedback processes, as well as feedback due to active galactic nuclei. We show that star formation activity significantly influences the halo relaxation response throughout its evolutionary history, with essentially immediate effects in the inner haloes and delayed effects of 2 to 3 Gyr in the outer regions. Metal content shows a weaker connection to relaxation than star formation rates, but the accumulated wind from feedback processes exhibits a stronger correlation. These findings enhance our understanding of halo relaxation mechanisms. Our estimates of the time-scales relevant for dark matter relaxation can potentially improve the description of halo profiles in existing baryonification schemes and semi-analytical galaxy formation models. Our results also show how the relaxation response of dark haloes can probe the evolutionary history of the galaxies they host.