Rest-frame UV versus optical morphologies of galaxies using Sersic
  profile fitting: the importance of morphological K-correction
  We show a comparison of the rest-frame UV morphologies of a sample of 162
intermediate redshift (median redshift 1.02) galaxies with their rest-frame
optical morphologies. We select our sample from the deepest near-UV image
obtained with the Hubble Space Telescope (HST) using the WFPC2 (F300W) as part
of the parallel observations of the Hubble Ultra Deep Field campaign
overlapping with the HST/ACS GOODS dataset. We perform single component Sersic
fits in both WFPC2/F300W (rest-frame UV) and ACS/F850LP (rest-frame optical)
bands and deduce that the Sersic index $n$ is estimated to be smaller in the
rest-frame UV compared to the rest-frame optical, leading to an overestimation
of the number of merger candidates by ~40-100% compared to the rest-frame
optical depending upon the cutoff in $n$ employed for identifying merger
candidates. This effect seems to be dominated by galaxies with low values of
n(F300W) <= 0.5 that have a value of n(F850LP) ~ 1.0. We argue that these
objects are probably clumpy starforming galaxies or minor mergers, both of
which are essentially contaminants, if one is interested in identifying major
mergers.
  In addition we also find evidence that the axis ratio b/a is lower, i.e.
ellipticity (1-b/a) is higher in rest-frame UV compared to the rest-frame
optical. Moreover, we find that in the rest-frame UV, the number of high
ellipticity (e >= 0.8) objects are higher by a factor of ~2.8 compared to the
rest-frame optical. This indicates that the reported dominance of elongated
morphologies among high-z LBGs might just be a bias related to the use of
rest-frame UV datasets in high-z studies.
