HOW LYMAN ALPHA EMISSION DEPENDS ON GALAXY STELLAR MASS

Abstract

In this work, we show how the stellar mass ( M * ) of galaxies affects the 3 <  z  < 4.6 Ly α equivalent width (EW) distribution. To this end, we design a sample of 629 galaxies in the M * range from the 3D-HST/CANDELS survey. We perform spectroscopic observations of this sample using the Michigan/Magellan Fiber System, allowing us to measure Ly α fluxes and use 3D-HST/CANDELS ancillary data. In order to study the Ly α EW distribution dependence on M * , we split the whole sample in three stellar mass bins. We find that, in all bins, the distribution is best represented by an exponential profile of the form . Through a Bayesian analysis, we confirm that lower M * galaxies have higher Ly α EWs. We also find that the fraction A of galaxies featuring emission and the e-folding scale W 0 of the distribution anti-correlate with M * , recovering expressions of the forms and . These results are crucial for proper interpretation of Ly α emission trends reported in the literature that may be affected by strong M * selection biases.