Which halos host Herschel-ATLAS galaxies in the local Universe?

TL;DR

This study analyzes the clustering of low-redshift Herschel-ATLAS galaxies and finds they are typically hosted by halos similar in mass to the Milky Way, with brighter, more star-forming galaxies residing in more massive halos.

Contribution

It provides the first cross-correlation measurement between Herschel-ATLAS far-IR galaxies and optical GAMA galaxies, revealing their typical halo masses and luminosity-dependent clustering.

Findings

H-ATLAS galaxies have a correlation length of ~4.63 Mpc.

H-ATLAS galaxies are hosted by halos comparable to the Milky Way.

Brighter, star-forming galaxies are more strongly clustered.

Abstract

We measure the projected cross-correlation between low redshift (z < 0.5) far-IR selected galaxies in the SDP field of the Herschel-ATLAS (H-ATLAS) survey and optically selected galaxies from the Galaxy and Mass Assembly (GAMA) redshift survey. In order to obtain robust correlation functions, we restrict the analysis to a subset of 969 out of 6900 H-ATLAS galaxies, which have reliable optical counterparts with r<19.4 mag and well-determined spectroscopic redshifts. The overlap region between the two surveys is 12.6 sq. deg; the matched sample has a median redshift of z ~ 0.2. The cross-correlation of GAMA and H-ATLAS galaxies within this region can be fitted by a power law, with correlation length r_0 ~ 4.63 +/- 0.51 Mpc. Comparing with the corresponding auto-correlation function of GAMA galaxies within the SDP field yields a relative bias (averaged over 2-8 Mpc) of H-ATLAS and GAMA galaxies of b_H/b_G ~ 0.6. Combined with clustering measurements from previous optical studies, this indicates that most of the low redshift H-ATLAS sources are hosted by halos with masses comparable to that of the Milky Way. The correlation function appears to depend on the 250 um luminosity, L_250, with bright (median luminosity \nu L_250 ~ 1.6 x 10^10 L_sun) objects being somewhat more strongly clustered than faint (\nu L_250 ~ 4.0 x 10^9 L_sun) objects. This implies that galaxies with higher dust-obscured star formation rates are hosted by more massive halos.