A Multiwavelength Study of Tadpole Galaxies in the Hubble Ultra Deep
  Field
  Multiwavelength data are essential in order to provide a complete picture of
galaxy evolution and to inform studies of galaxies' morphological properties
across cosmic time. Here we present results of a multiwavelength investigation
of the morphologies of "tadpole" galaxies at intermediate redshift
(0.314<z<3.175) in the Hubble Ultra Deep Field. These galaxies were previously
selected from deep Hubble Space Telescope (HST) F775W data based on their
distinct asymmetric knot-plus-tail morphologies (Straughn et al. 2006). Here we
use deep Wide Field Camera 3 near-infrared imaging in addition to the HST
optical data in order to study the rest-frame UV/optical morphologies of these
galaxies across the redshift range 0.3<z<3.2. This study reveals that the
majority of these galaxies do retain their general asymmetric morphology in the
rest-frame optical over this redshift range, if not the distinct "tadpole"
shape. The average stellar mass of tadpole galaxies is lower than field
galaxies, with the effect being slightly greater at higher redshift within the
errors. Estimated from SED fits, the average age of tadpole galaxies is younger
than field galaxies in the lower redshift bin, and the average metallicity is
lower (whereas the specific star formation rate for tadpoles is roughly the
same as field galaxies across the redshift range probed here). These average
effects combined support the conclusion that this subset of galaxies is in an
active phase of assembly, either late-stage merging or cold gas accretion
causing localized clumpy star-formation.
