THE WYOMING SURVEY FOR H{alpha}. II. H{alpha} LUMINOSITY FUNCTIONS AT z{approx} 0.16, 0.24, 0.32, AND 0.40

Abstract

The Wyoming Survey for H{alpha}, or WySH, is a large-area, ground-based imaging survey for H{alpha}-emitting galaxies at redshifts of z {approx} 0.16, 0.24, 0.32, and 0.40. The survey spans up to 4 deg{sup 2} in a set of fields of low Galactic cirrus emission, using twin narrowband filters at each epoch for improved stellar continuum subtraction. H{alpha} luminosity functions are presented for each {delta}z {approx} 0.02 epoch based on a total of nearly 1200 galaxies. These data clearly show an evolution with look-back time in the volume-averaged cosmic star formation rate. Integrals of Schechter fits to the incompleteness- and extinction-corrected H{alpha} luminosity functions indicate star formation rates per comoving volume of 0.010, 0.013, 0.020, 0.022 h {sub 70} M {sub sun} yr{sup -1} Mpc{sup -3} at z {approx} 0.16, 0.24, 0.32, and 0.40, respectively. Combined statistical and systematic measurement uncertainties are on the order of 25%, while the effects of cosmic variance are at the 20% level. The bulk of this evolution is driven by changes in the characteristic luminosity L {sub *} of the H{alpha} luminosity functions, with L {sub *} for the earlier two epochs being a factor of 2 larger than L {sub *} at the lattermore » two epochs; it is more difficult with this data set to decipher systematic evolutionary differences in the luminosity function amplitude and faint-end slope. Coupling these results with a comprehensive compilation of results from the literature on emission line surveys, the evolution in the cosmic star formation rate density over 0 {approx}< z {approx}< 1.5 is measured.« less