An Ultraviolet Redshift Survey: A New Estimate of the Local Star Formation Rate

Abstract

We present the first results of an ongoing spectroscopic survey of galaxies selected in the rest-frame ultraviolet. The source catalogue was constructed from a flux-limited sample of stars, galaxies and QSOs imaged at 2000 Åwith the FOCA balloon-borne camera (Milliard et al. 1992). The redshift distribution obtained for 45 galaxies spans 0<z<0.3 and a high fraction of the spectra show intense nebular emission lines and ultraviolet-optical colors considerably bluer than can be accounted for via normal Hubble sequence galaxies. From the rest-frame ultraviolet galaxy luminosity function, and adopting a normal IMF, we use the integrated UV light to our survey limit to estimate the local volume averaged star formation rate. We find a value significantly larger than recent estimates and argue this must be a lower limit to the true value. Our results suggest the local abundance of star-forming galaxies has been underestimated in surveys based on optical data.