Galaxy And Mass Assembly: Evolution of the Halpha luminosity function and star formation rate density up to z<0.35

TL;DR

This study uses extensive spectroscopic data from GAMA and SDSS to accurately measure the evolution of the Halpha luminosity function and star formation rate density up to redshift 0.35, addressing previous discrepancies.

Contribution

It provides a robust measurement of the low-z Halpha luminosity function evolution and introduces a Saunders functional form to better describe the bright end.

Findings

The bright end of the luminosity function is best described by a Saunders function.

The star formation rate density decreases with redshift up to z<0.35.

Incompleteness issues arise from magnitude limits affecting bright Halpha sources.

Abstract

Measurements of the low-z Halpha luminosity function have a large dispersion in the local number density of sources, and correspondingly in the SFR density. The possible causes for these discrepancies include limited volume sampling, biases arising from survey sample selection, different methods of correcting for dust obscuration and AGN contamination. The Galaxy And Mass Assembly (GAMA) survey and Sloan Digital Sky Survey (SDSS) provide deep spectroscopic observations over a wide sky area enabling detection of a large sample of star-forming galaxies spanning 0.001<SFR(Halpha)<100 with which to robustly measure the evolution of the SFR density in the low-z universe. The large number of high SFR galaxies present in our sample allow an improved measurement of the bright end of the luminosity function, indicating that the decrease in number density of sources at bright luminosities is best described by a Saunders functional form rather than the traditional Schechter function. This result is consistent with other published luminosity functions in the FIR and radio. For GAMA and SDSS we find the r-band apparent magnitude limit, combined with the subsequent requirement for Halpha detection leads to an incompleteness due to missing bright Halpha sources with faint r-band magnitudes.