Galaxy and Mass Assembly (GAMA): Projected Galaxy Clustering

TL;DR

This study measures galaxy clustering in the GAMA survey across different redshifts, compares results with galaxy formation models, and identifies discrepancies to guide future model improvements.

Contribution

Developed an enhanced method for creating random catalogues to accurately measure galaxy correlation functions in the GAMA survey.

Findings

More luminous, massive, and redder galaxies are more strongly clustered.

Red galaxies show stronger clustering on scales less than ~3 h^{-1} Mpc.

Models reproduce the trend of stronger clustering for massive galaxies but underpredict blue galaxy clustering.

Abstract

We measure the projected 2-point correlation function of galaxies in the 180 deg$^2$ equatorial regions of the GAMA II survey, for four different redshift slices between z = 0.0 and z=0.5. To do this we further develop the Cole (2011) method of producing suitable random catalogues for the calculation of correlation functions. We find that more r-band luminous, more massive and redder galaxies are more clustered. We also find that red galaxies have stronger clustering on scales less than ~3 $h^{-1}$ Mpc. We compare to two different versions of the GALFORM galaxy formation model, Lacey et al (in prep.) and Gonzalez-Perez et al. (2014), and find that the models reproduce the trend of stronger clustering for more massive galaxies. However, the models under predict the clustering of blue galaxies, can incorrectly predict the correlation function on small scales and under predict the clustering in our sample of galaxies with ~3$L_r$ . We suggest possible avenues to explore to improve these cluster- ing predictions. The measurements presented in this paper can be used to test other galaxy formation models, and we make the measurements available online to facilitate this.