Unraveling the interplay between SIDM and baryons in MW halos: defining where baryons dictate heat transfer

TL;DR

This study uses advanced simulations to explore how baryons influence the thermal structure of MW-like halos in the presence of velocity-dependent SIDM, revealing baryons' dominant role over SIDM scatterings in shaping halo cores.

Contribution

It introduces a novel simulation approach combining SIDM and baryons, and a simplified DMO model to analyze their interplay in galaxy evolution.

Findings

Baryons significantly alter the thermal structure of MW-like halos.

SIDM creates cuspier densities due to baryon-induced heat transfer.

Effects are prominent in galaxies with stellar mass from 10^8 to 10^11 solar masses.

Abstract

We present a new set of cosmological zoom-in simulations of a MW-like galaxy which for the first time include elastic velocity-dependent self interacting dark matter (SIDM) and IllustrisTNG physics. With these simulations we investigate the interaction between SIDM and baryons and its effects on the galaxy evolution process. We also introduce a novel set of modified DMO simulations which can reasonably replicate the effects of fully realized hydrodynamics on the DM halo while simplifying the analysis and lowering the computational cost. We find that baryons change the thermal structure of the central region of the halo to a greater extent than the SIDM scatterings for MW-like galaxies. Additionally, we find that the new thermal structure of the MW-like halo causes SIDM to create cuspier central densities rather than cores because the SIDM scatterings remove the thermal support by transferring heat away from the center of the galaxy. We find that this effect, caused by baryon contraction, begins to affect galaxies with a stellar mass of $10^8$ M$_\odot$ and increases in strength to the MW-mass scale. This implies that any simulations used to constrain the SIDM cross sections for galaxies with stellar masses between $10^8$ and at least $10^{11}$ M$_\odot$ will require baryons to make accurate predictions.