Spiral Galaxies as Progenitors of Pseudobulge Hosting S0s
  We present observations of pseudobulges in S0 and spiral galaxies using
imaging data taken with the Spitzer Infra-Red Array Camera. We have used 2-d
bulge-disk-bar decomposition to determine structural parameters of 185 S0
galaxies and 31 nearby spiral galaxies. Using the Sersic index and the position
on the Kormendy diagram to classify their bulges as either classical or pseudo,
we find that 25 S0s (14%) and 24 spirals (77%) host pseudoblges. The fraction
of pseudobulges we find in spiral galaxies is consistent with previous results
obtained with optical data and show that the evolution of a large fraction of
spirals is governed by secular processes rather than by major mergers. We find
that the bulge effective radius is correlated with the disk scale length for
pseudobulges of S0s and spirals, as expected for secular formation of bulges
from disk instabilities, though the disks in S0s are significantly smaller than
those in spirals. We show that early-type pseudobulge hosting spirals can
transform to pseudobulge hosting S0s by simple gas stripping. However, simple
gas stripping mechanism is not sufficient to transform the late-type
pseudobulge hosting spirals into pseudobulge hosting S0s.
