The AIDA-TNG project: gas distributions inside and around haloes

TL;DR

This study uses cosmological simulations to compare gas and neutral hydrogen distributions in different dark matter models, finding minimal impact on median profiles but some distinctions in specific cases, especially for SIDM.

Contribution

It provides the first detailed predictions of gas and HI distributions across multiple dark matter models using the AIDA-TNG simulation suite, including fitting functions and observational strategies.

Findings

DM models have limited impact on median gas and HI profiles.

SIDM shows more HI near the centre compared to other models.

Distinguishing DM models via galaxy-Lyα cross-correlation is feasible with current surveys.

Abstract

The nature of Dark Matter (DM) is one of the most outstanding mysteries of modern astrophysics. While the standard Cold DM (CDM) model successfully explains observations on most astrophysical scales, DM particles have not yet been detected, leaving room for a plethora of different models. In order to identify their observable signatures, we use the AIDA-TNG cosmological simulation suite to predict the distributions of gas and neutral hydrogen (HI) in the CDM, Self-Interacting DM (SIDM), velocity-dependent SIDM (vSIDM), and Warm DM (WDM) models. We find that the DM models investigated have very limited impact on the median gas and HI profile of haloes. In particular, for the most massive haloes ($M_{\rm vir}\sim10^{14}\,\mathrm{M}_\odot$), we find that DM self-interactions can shallow the central potential and thereby enhance gas cooling. We find that, in all models, the halo-to-halo variation in the HI profiles is explained by AGN feedback, and that the specific characteristics of DM model is largely subdominant. Nevertheless, we detect some systematic difference in the case of SIDM, with more HI surviving close to the centre with respect to other models. We provide fitting functions for the gas and HI profiles. We investigate the galaxy-Ly$\alpha$ cross-correlation function (\galacc) for different halo masses, redshift and observation strategies. We find that at $z=0$ vSIDM can be distinguished from CDM in haloes with $10^{12}\lesssim M_{\rm vir}\lesssim10^{13}\,{\rm M}_\odot$, while SIDM1 can be distinguished from CDM in haloes with $M_{\rm vir}\gtrsim10^{13}\,{\rm M}_\odot$. We estimate that statistically-robust detection requires sampling $\sim160$ haloes with $\sim20$ sightlines each, a task that can be achieved with current and future facilities like WEAVE, 4MOST, PFS, ELT and WST.