Correlations among Global Photometric Properties of Disk Galaxies

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.