Citation:
Date Published:
May 1, 2001Abstract:
In the course of its commissioning observations, the Sloan Digital SkySurvey (SDSS) has produced one of the largest redshift samples ofgalaxies selected from CCD images. Using 11,275 galaxies complete tor*=17.6 over 140 deg2, we compute the luminosityfunction of galaxies in the r* band over a range-23r*<-16 (for h=1). The result iswell-described by a Schechter function with parametersφ*=(1.46+/-0.12)×10-2 h3Mpc-3, M*=-20.83+/-0.03, and α=-1.20+/-0.03.The implied luminosity density in r* isj~(2.6+/-0.3)×108h Lsolar Mpc-3.We find that the surface brightness selection threshold has a negligibleimpact for Mr*<-18. Using subsets of the data,we measure the luminosity function in the u*, g*,i*, and z* bands as well; the slope at lowluminosities ranges from α=-1.35 to α=-1.2. We measure thebivariate distribution of r* luminosity with half-lightsurface brightness, intrinsic g*-r* color, andmorphology. In agreement with previous studies, we find that highsurface brightness, red, highly concentrated galaxies are on averagemore luminous than low surface brightness, blue, less concentratedgalaxies. An important feature of the SDSS luminosity function is theuse of Petrosian magnitudes, which measure a constant fraction of agalaxy's total light regardless of the amplitude of its surfacebrightness profile. If we synthesize results for RGKC band orbj band using these Petrosian magnitudes, we obtainluminosity densities 2 times that found by the Las Campanas RedshiftSurvey in RGKC and 1.4 times that found by the Two DegreeField Galaxy Redshift Survey in bj. However, we are able toreproduce the luminosity functions obtained by these surveys if we alsomimic their isophotal limits for defining galaxy magnitudes, which areshallower and more redshift dependent than the Petrosian magnitudes usedby the SDSS. Based on observations obtained with the Sloan Digital SkySurvey.