The faint end of the 250 micron luminosity function at z < 0.5

TL;DR

This study extends the 250 micron luminosity function to much fainter luminosities using a novel stacking method, revealing significant luminosity evolution and moderate density evolution of galaxies at z<0.5.

Contribution

The paper introduces a modified stacking technique to accurately reconstruct the faint end of the 250 micron luminosity function from optically selected galaxies.

Findings

LF extended to 25 times fainter luminosities

Strong positive luminosity evolution with redshift

Moderate negative density evolution over z=[0.02, 0.5]

Abstract

Aims. We aim to study the 250 micron luminosity function (LF) down to much fainter luminosities than achieved by previous efforts. Methods. We developed a modified stacking method to reconstruct the 250 micron LF using optically selected galaxies from the SDSS survey and Herschel maps of the GAMA equatorial fields and Stripe 82. Our stacking method not only recovers the mean 250 micron luminosities of galaxies that are too faint to be individually detected, but also their underlying distribution functions. Results. We find very good agreement with previous measurements in the overlapping luminosity range. More importantly, we are able to derive the LF down to much fainter luminosities (around 25 times fainter) than achieved by previous studies. We find strong positive luminosity evolution \propto (1 + z)^4.89\pm1.07 and moderate negative density evolution \propto (1 + z)^-1.02\pm0.54 over the redshift range z=[0.02, 0.5].