Finite Resolution Deconvolution of Multi-Wavelength Imaging of 20,000
  Galaxies in the COSMOS Field: The Evolution of Clumpy Galaxies Over Cosmic
  Time
  Compact star-forming clumps observed in distant galaxies are often suggested
to play a crucial role in galaxy assembly. In this paper, we use a novel
approach of applying finite resolution deconvolution on ground-based images of
the COSMOS field to resolve 20,185 star-forming galaxies (SFG) at 0.5<z<2 to an
angular resolution of 0.3", and study their clumpy fractions. A comparison
between the deconvolved and HST images across four different filters shows good
agreement and validates the deconvolution. We model spectral energy
distributions using the deconvolved 14-band images to provide resolved surface
brightness and stellar mass density maps for these galaxies. We find that the
fraction of clumpy galaxies decreases with increasing stellar masses, and with
increasing redshift: from ~30% at z ~ 0.7 to ~50% at z ~ 1.7. Using abundance
matching, we also trace the progenitors for galaxies at z ~ 0.7 and measure the
fractional mass contribution of clumps toward their total mass budget. Clumps
are observed to have a higher fractional mass contribution toward galaxies at
higher redshift: increasing from ~1% at z ~ 0.7 to ~5% at z ~ 1.7. Finally, the
majority of clumpy SFGs have higher specific star formation rates (sSFR)
compared to the average SFGs at fixed stellar mass. We discuss the implication
of this result to in-situ clump formation due to disk instability.
