Deconstructing the Galaxy Stellar Mass Function with UKIDSS and CANDELS: the Impact of Colour, Structure and Environment

TL;DR

This study combines multiple deep galaxy surveys to analyze how galaxy properties like colour, structure, and environment influence the galaxy stellar mass function across a broad redshift range, revealing mass-dependent quenching and environmental effects.

Contribution

It provides a comprehensive analysis of the galaxy stellar mass function using combined datasets, highlighting the links between morphology, environment, and star formation quenching.

Findings

Double Schechter function fits high Sersic index galaxies.

High-mass galaxies are more prevalent in dense environments.

Mass-dependent quenching mechanisms are suggested.

Abstract

We combine photometry from the UDS, and CANDELS UDS and CANDELS GOODS-S surveys to construct the galaxy stellar mass function probing both the low and high mass end accurately in the redshift range 0.3<z<3. The advantages of using a homogeneous concatenation of these datasets include meaningful measures of environment in the UDS, due to its large area (0.88 deg^2), and the high resolution deep imaging in CANDELS (H_160 > 26.0), affording us robust measures of structural parameters. We construct stellar mass functions for the entire sample as parameterised by the Schechter function, and find that there is a decline in the values of phi and of alpha with higher redshifts, and a nearly constant M* up to z~3. We divide the galaxy stellar mass function by colour, structure, and environment and explore the links between environmental over-density, morphology, and the quenching of star formation. We find that a double Schechter function describes galaxies with high Sersic index (n>2.5), similar to galaxies which are red or passive. The low-mass end of the n>2.5 stellar mass function is dominated by blue galaxies, whereas the high-mass end is dominated by red galaxies. This hints that possible links between morphological evolution and star formation quenching are only present in high-mass galaxies. This is turn suggests that there are strong mass dependent quenching mechanisms. In addition, we find that the number density of high mass systems is elevated in dense environments, suggesting that an environmental process is building up massive galaxies quicker in over densities than in lower densities.