Correlations among global photometric properties of disk galaxies

Abstract

Using a two-dimensional galaxy image decomposition technique, we extract global bulge and disk parameters for a complete sample of early-type disk galaxies in the near-infrared K band. We find significant correlation of the bulge parameter n with the central bulge surface brightness μ_b(0) and with effective radius r_e. Using bivariate analysis techniques, we find that log n, log r_e, and μ_b(0) are distributed in a plane with small scatter. We do not find a strong correlation of n with bulge-to-disk luminosity ratio, contrary to earlier reports. For these early-type disk galaxies, r_e and the disk scale length r_d are well correlated, but with large scatter. We examine the implications of our results for various bulge formation scenarios in disk galaxies.