Angular momentum and clustering properties of early dark matter halos

TL;DR

This study examines the angular momentum and clustering of early dark matter halos at high redshift, revealing that higher spin halos are more strongly clustered, consistent with tidal torque theory.

Contribution

It provides the first detailed analysis of spin distributions and clustering differences of low-mass halos at high redshift, supporting tidal torque theory.

Findings

Spin distributions are log-normal and unchanged with redshift.

High spin halos are more strongly clustered than low spin halos.

Results support the tidal torquing model for angular momentum acquisition.

Abstract

In this paper we study the angular momentum properties of simulated dark matter halos at high redshift that likely host the first stars in the Universe. Calculating the spin distributions of these $10^6 - 10^7 \Msun$ halos in redshift slices from $z = 15 - 6$, we find that they are well fit by a log-normal distribution as is found for lower redshift and more massive halos in earlier work. We find that both the mean value of the spin and dispersion are largely unchanged with redshift for all halos. Our key result is that subsamples of low and high spin $10^6 \Msun$ and $10^7 \Msun$ halos show difference in clustering strength. In both mass bins, higher spin halos are more strongly clustered in concordance with a tidal torquing picture for the growth of angular momentum in dark matter halos in the CDM paradigm.