Spheroidal post-mergers in the local Universe
  Galaxy merging is a fundamental aspect of the standard hierarchical galaxy
formation paradigm. Recently, the Galaxy Zoo project has compiled a large,
homogeneous catalogue of 3373 mergers, through direct visual inspection of the
entire SDSS spectro- scopic sample. We explore a subset of galaxies from this
catalogue that are spheroidal 'post-mergers' (SPMs) - where a single remnant is
in the final stages of relaxation after the merger and shows evidence for a
dominant bulge, making them plausible progenitors of early-type galaxies. Our
results indicate that the SPMs have bluer colours than the general early-type
galaxy population possibly due to merger-induced star formation. An analysis
using optical emission line ratios indicates that 20 of our SPMs exhibit LINER
or Seyfert-like activity (68%), while the remaining 10 galaxies are classified
as either star forming (16%) or quiescent (16%). A comparison to the emission
line activity in the ongoing mergers from Darg et al. indicates that the AGN
fraction rises in the post-mergers, suggesting that the AGN phase probably
becomes dominant only in the very final stages of the merger process. The
optical colours of the SPMs and the plausible mass ratios for their progenitors
indicate that, while a minority are consistent with major mergers between two
early-type galaxies, the vast majority are remnants of major mergers where at
least one progenitor is a late-type galaxy.
