Kavli Affiliate: Luis C. Ho
| First 5 Authors: Hua Gao, Luis C. Ho, Zhao-Yu Li, ,
| Summary:
We measure optical colors for the bulges of 312 disk galaxies from the
Carnegie-Irvine Galaxy Survey and convert their previously available $R$-band
structural parameters to stellar mass parameters. We also measure their average
stellar mass surface density in the central 1 kpc ($Sigma_{1}$). Comparing the
mass-based Kormendy relation with the original one based on flux, we find that
the majority of the classifications into classical and pseudo bulges, as well
as their overall statistical properties, remain essentially unchanged. While
the bulge type classifications of the Kormendy relation are robust against
stellar population effects, the mass-based classification criteria do produce
better agreement between bulge structural properties and their stellar
populations. Moreover, the mass-based Kormendy relation reveals a population of
ultra-dense bulges akin to high-$z$ compact early-type galaxies, which are
otherwise hidden in the original Kormendy relation. These bulges are probably
relics of spheroids assembled in the early Universe, although for some we
cannot rule out some contribution from secular growth. We confirm previous
studies that $Sigma_1$ correlates well with bulge surface densities.
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