The Luminosity Function of Galaxies in SDSS Commissioning Data

Abstract

During commissioning observations, the Sloan Digital Sky Survey (SDSS) has produced one of the largest existing galaxy redshift samples selected from CCD images. Using 11,275 galaxies complete to r^* = 17.6 over 140 square degrees, we compute the luminosity function of galaxies in the r^* band over a range -23 < M < -16 (for h=1). The result is well-described by a Schechter function with parameters phi_* = 0.0146 +/- 0.0012 h^3 Mpc^{-3}, M_* = -20.83 +/- 0.03, and alpha = -1.20 +/- 0.03. The implied luminosity density in r^* is j = (2.6 +/- 0.3) x 10^8 h L_sun Mpc^{-3}. The surface brightness selection threshold has a negligible impact for M < -18. We measure the luminosity function in the u^*, g^*, i^*, and z^* bands as well; the slope at low luminosities ranges from alpha=-1.35 to alpha=-1.2. We measure the bivariate distribution of r^* luminosity with half-light surface brightness, intrinsic color, and morphology. High surface brightness, red, highly concentrated galaxies are on average more luminous than low surface brightness, blue, less concentrated galaxies. If we synthesize results for R-band or b_j-band using the Petrosian magnitudes with which the SDSS measures galaxy fluxes, we obtain luminosity densities 2.0 times that found by the Las Campanas Redshift Survey in R and 1.4 times that found by the Two-degree Field Galaxy Redshift Survey in b_j. We are able to reproduce the luminosity functions obtained by these surveys if we also mimic their isophotal limits for defining galaxy magnitudes, which are shallower and more redshift dependent than the Petrosian magnitudes used by the SDSS. (Abridged)Comment: 49 pages, including 23 figures, accepted by AJ; some minor textual changes, plus an important change in comparison to LCR

HOST GALAXY PROPERTIES OF THESWIFTBAT ULTRA HARD X-RAY SELECTED ACTIVE GALACTIC NUCLEUS

“…To ensure that the AGN emission was properly removed, we performed simulations of AGN galaxies to test GALFIT and also checked the subtraction for BAT AGN (see Appendix A for a discussion). A modified form of the Petrosian system, the same as is used in the SDSS automated pipeline, was used for photometry (Blanton et al 2001) for both the SDSS and Kitt Peak observed BAT AGN galaxies. The Petrosian aperture is determined to be large enough to enclose almost all of the flux for typical galaxy profiles, but small enough that the sky noise is not significant.…”

The Space Density of Extended Ultraviolet (Xuv) Disks in the Local Universe and Implications for Gas Accretion Onto Galaxies

“…NUV and FUV Petrosian magnitudes (as described in Blanton et al 2001;Yasuda et al 2001) were computed using a custom code in which nearby objects are masked. We used the NUV image to determine the Petrosian radius, which we then used to define the photometric aperture for the NUV and FUV images.…”

Magnification of light from many distant quasars by gravitational lenses

“…Galaxies having i * < 22.2 (around 30% of the potential lens population) are not considered part of the lens population. To compute i * for a galaxy having velocity dispersion σ at redshift z, we use L g⋆ from the 2dF early-type galaxy luminosity function 19 , the Faber-Jackson relation, color transformations with a k-correction 20,21 , and the evolution of the rest-frame B-band mass-to-light ratio 22 .…”