The role of spin in the formation and evolution of galaxies

TL;DR

This study analyzes the relationship between dark matter halo spin and galaxy properties using SDSS data, revealing anti-correlation with stellar mass, links to recent star formation, and minimal environmental influence.

Contribution

It provides the first large-scale analysis of dark matter halo spin in relation to galaxy star formation history and environment.

Findings

Low mass galaxies tend to have higher dark matter spins.

Galaxies with recent star formation have higher and more varied spins.

Halo spin shows little correlation with galaxy environment.

Abstract

Using the SDSS spectroscopic sample, we estimate the dark matter halo spin parameter lambda for ~53,000 disk galaxies for which MOPED star formation histories are available. We investigate the relationship between spin and total stellar mass, star formation history, and environment. First, we find a clear anti-correlation between stellar mass and spin, with low mass galaxies generally having high dark matter spins. Second, galaxies which have formed more than ~5% of their stars in the last 0.2 Gyr have more broadly distributed and typically higher spins (including a significant fraction with lambda > 0.1) than galaxies which formed a large fraction of their stars more than 10 Gyr ago. Finally, we find little or no correlation between the value of spin of the dark halo and environment as determined both by proximity to a new cluster catalog and a marked correlation study. This agrees well with the predictions from linear hierarchical torquing theory and numerical simulations.