Galaxy And Mass Assembly (GAMA): the Stellar Mass Budget by Galaxy Type

TL;DR

This study expands the morphological classification of galaxies in the GAMA survey, deriving stellar mass functions for different galaxy types and estimating their contributions to the total stellar mass density in the local universe.

Contribution

It provides updated morphological classifications for a larger galaxy sample and derives stellar mass functions for each class, including a lower mass limit, improving understanding of galaxy mass distribution.

Findings

Total stellar mass density is approximately 2.5 x 10^8 Msun Mpc^-3 h_0.7.

Spheroid-dominated galaxies contribute about 70% to stellar mass density.

Disk-dominated galaxies contribute about 30% to stellar mass density.

Abstract

We report an expanded sample of visual morphological classifications from the Galaxy and Mass Assembly (GAMA) survey phase two, which now includes 7,556 objects (previously 3,727 in phase one). We define a local (z <0.06) sample and classify galaxies into E, S0-Sa, SB0-SBa, Sab-Scd, SBab-SBcd, Sd-Irr, and "little blue spheroid" types. Using these updated classifications, we derive stellar mass function fits to individual galaxy populations divided both by morphological class and more general spheroid- or disk-dominated categories with a lower mass limit of log(Mstar/Msun) = 8 (one dex below earlier morphological mass function determinations). We find that all individual morphological classes and the combined spheroid-/bulge-dominated classes are well described by single Schechter stellar mass function forms. We find that the total stellar mass densities for individual galaxy populations and for the entire galaxy population are bounded within our stellar mass limits and derive an estimated total stellar mass density of rho_star = 2.5 x 10^8 Msun Mpc^-3 h_0.7, which corresponds to an approximately 4% fraction of baryons found in stars. The mass contributions to this total stellar mass density by galaxies that are dominated by spheroidal components (E and S0-Sa classes) and by disk components (Sab-Scd and Sd-Irr classes) are approximately 70% and 30%, respectively.