Astrophysically Motivated Bulge-Disk Decompositions of SDSS Galaxies
  We present a set of bulge-disk decompositions for a sample of 71,825 SDSS
main-sample galaxies in the redshift range 0.003<z<0.05. We have fit each
galaxy with either a de Vaucouleurs ('classical') or an exponential ('pseudo-')
bulge and an exponential disk. Two dimensional Sersic fits are performed when
the 2-component fits are not statistically significant or when the fits are
poor, even in the presence of high signal-to-noise. We study the robustness of
our 2-component fits by studying a bright subsample of galaxies and we study
the systematics of these fits with decreasing resolution and S/N. Only 30% of
our sample have been fit with two-component fits in which both components are
non-zero. The g-r and g-i colours of each component for the two-component
models are determined using linear templates derived from the r-band model. We
attempt a physical classification of types of fits into disk galaxies,
pseudo-bulges, classical bulges, and ellipticals. Our classification of
galaxies agrees well with previous large B+D decomposed samples. Using our
galaxy classifications, we find that Petrosian concentration is a good
indicator of B/T, while overall Sersic index is not. Additionally, we find that
the majority of green valley galaxies are bulge+disk galaxies. Furthermore, in
the transition from green to red B+D galaxies, the total galaxy colour is most
strongly correlated with the disk colour.
