The feasibility of constraining DM interactions with high-redshift observations by JWST

TL;DR

This study uses cosmological simulations to explore how different dark matter models affect high-redshift galaxy formation and clustering, aiming to inform future JWST observations and constrain dark matter properties.

Contribution

It demonstrates that high-redshift galaxy abundance, formation timing, and clustering are sensitive to dark matter interactions, providing new observational avenues to distinguish DM models.

Findings

DM interactions suppress low-mass galaxy formation below 10^8 solar masses.

Power spectrum cutoff delays structure formation in interacting DM models.

Galaxy clustering at high redshift depends on DM physics, but may be challenging to measure with JWST.

Abstract

Observations of the high redshift universe provide a promising avenue for constraining the nature of the dark matter (DM). This will be even more true with the advent of the James Webb Space Telescope (JWST). We run cosmological simulations of galaxy formation as part of the Effective Theory of Structure Formation (ETHOS) project to compare high redshift galaxies in Cold (CDM) and alternative DM models which have varying relativistic coupling and self-interaction strengths. The interacting DM scenarios produce a cutoff in the linear power spectrum on small-scales, followed by a series of "dark acoustic oscillations". We find that DM interactions suppress the abundance of galaxies below $M_\star \sim 10^8\,M_\odot$ for the models considered. The cutoff in the power spectrum delays structure formation relative to CDM. Objects in ETHOS that end up at the same final masses as their CDM counterparts are characterised by a more vigorous phase of early star formation. While galaxies with $M_\star \lesssim 10^6\,M_\odot$ make up more than 60 per cent of star formation in CDM at $z\approx 10$, they contribute only about half the star formation density in ETHOS. These differences diminish with decreasing redshift. We find that the effects of DM self-interactions are negligible compared to effects of relativistic coupling (i.e. the effective initial conditions for galaxy formation) in all properties of the galaxy population we examine. Finally, we show that the clustering strength of galaxies at high redshifts depends sensitively on DM physics, although these differences are manifest on scales that may be too small to be measurable by JWST.