Galaxy And Mass Assembly (GAMA): The dependence of the galaxy luminosity function on environment, redshift and colour

TL;DR

This study measures how the galaxy luminosity function varies with environment, redshift, and colour using GAMA survey data, and compares results with galaxy formation models.

Contribution

It provides detailed measurements of the galaxy luminosity function dependence on environment, redshift, and colour, and tests the GALFORM model predictions against observational data.

Findings

LF varies smoothly with overdensity, with little evolution over 3 Gyrs.

GALFORM model matches observed LFs well in dense environments.

Discrepancies at faint and bright ends suggest issues with galaxy quenching and feedback.

Abstract

We use 80922 galaxies in the Galaxy And Mass Assembly (GAMA) survey to measure the galaxy luminosity function (LF) in different environments over the redshift range 0.04<z<0.26. The depth and size of GAMA allows us to define samples split by colour and redshift to measure the dependence of the LF on environment, redshift and colour. We find that the LF varies smoothly with overdensity, consistent with previous results, with little environmental dependent evolution over the last 3 Gyrs. The modified GALFORM model predictions agree remarkably well with our LFs split by environment, particularly in the most overdense environments. The LFs predicted by the model for both blue and red galaxies are consistent with GAMA for the environments and luminosities at which such galaxies dominate. Discrepancies between the model and the data seen in the faint end of the LF suggest too many faint red galaxies are predicted, which is likely to be due to the over-quenching of satellite galaxies. The excess of bright blue galaxies predicted in underdense regions could be due to the implementation of AGN feedback not being sufficiently effective in the lower mass halos.