A CATALOG OF BULGE+DISK DECOMPOSITIONS AND UPDATED PHOTOMETRY FOR 1.12 MILLION GALAXIES IN THE SLOAN DIGITAL SKY SURVEY

Abstract

We perform two-dimensional, Point-Spread-Function-convolved, bulge+disk\ndecompositions in the $g$ and $r$ bandpasses on a sample of 1,123,718 galaxies\nfrom the Legacy area of the Sloan Digital Sky Survey Data Release Seven. Four\ndifferent decomposition procedures are investigated which make improvements to\nsky background determinations and object deblending over the standard SDSS\nprocedures that lead to more robust structural parameters and integrated galaxy\nmagnitudes and colors, especially in crowded environments. We use a set of\nscience-based quality assurance metrics namely the disk luminosity-size\nrelation, the galaxy color-magnitude diagram and the galaxy central (fiber)\ncolors to show the robustness of our structural parameters. The best procedure\nutilizes simultaneous, two-bandpass decompositions. Bulge and disk photometric\nerrors remain below 0.1 mag down to bulge and disk magnitudes of $g \\simeq 19$\nand $r \\simeq 18.5$. We also use and compare three different galaxy fitting\nmodels: a pure Sersic model, a $n_b=4$ bulge + disk model and a Sersic (free\n$n_b$) bulge + disk model. The most appropriate model for a given galaxy is\ndetermined by the $F$-test probability. All three catalogs of measured\nstructural parameters, rest-frame magnitudes and colors are publicly released\nhere. These catalogs should provide an extensive comparison set for a wide\nrange of observational and theoretical studies of galaxies.\n