The Hα Luminosity Function of Morphologically Classified Galaxies in the Sloan Digital Sky Survey

Abstract

We present a study of the Halpha line emission from a sample of 1482 optically selected, morphologically classified bright galaxies (medianredshift of 0.05) derived from the Sloan Digital Sky Survey. Theluminosity function is calculated for each morphological class and forthe total sample. The luminosity function fitted with the Schechter formgives a slope alpha=-1.43+/-0.10 for the total sample, and theHalpha luminosity density is 10 39.31+/-0.04+0.10-0.07 h ergss -1 Mpc -3, where the first error is statisticaland the second is systematic. This value is consistent with that derivedby Gallego et al. in 1995, but this agreement is caused by a fortuitouscancellation of their neglect of stellar absorption that affects theestimate of extinction corrections and a significant sampleincompleteness of emission-line galaxies. The fraction of Halphaemitters monotonically increases from early (a few percent forelliptical galaxies) to late types (100% for irregular galaxies),whereas strong emitters exist in all classes of morphological types. Wefind that 83% of the luminosity density comes from spiral galaxies, 5%from irregular galaxies, and 9% from early-type galaxies; a small numberof morphologically disturbed galaxies contribute by 3%.