Spatial Clustering from GALEX-SDSS samples: Star Formation History and large-scale clustering

TL;DR

This study analyzes the spatial clustering of galaxies using GALEX and SDSS data, revealing how clustering varies with galaxy color, star formation rate, and stellar mass, and highlighting the environmental significance of star formation activity.

Contribution

It provides a detailed analysis of galaxy clustering dependence on galaxy properties, demonstrating the importance of star formation rate as an environmental indicator.

Findings

Clustering strength increases from blue to red galaxies.

Green valley galaxies have intermediate clustering, consistent with galaxy groups.

Star formation rate is a more sensitive environmental tracer than stellar mass.

Abstract

We measure the projected spatial correlation function w_p(r_p) from a large sample combining GALEX ultraviolet imaging with the SDSS spectroscopic sample. We study the dependence of the clustering strength for samples selected on (NUV - r)_abs color, specific star formation rate (SSFR), and stellar mass. We find that there is a smooth transition in the clustering of galaxies as a function of this color from weak clustering among blue galaxies to stronger clustering for red galaxies. The clustering of galaxies within the "green valley" has an intermediate strength, and is consistent with that expected from galaxy groups. The results are robust to the correction for dust extinction. The comparison with simple analytical modeling suggests that the halo occupation number increases with older star formation epochs. When splitting according to SSFR, we find that the SSFR is a more sensitive tracer of environment than stellar mass.