Title: Physical Properties of Sub-galactic Clumps at 0.5 $\leq z \leq$ 1.5 in the UVUDF,
Abstract: We present an investigation of clumpy galaxies in the Hubble Ultra Deep Field
at 0.5 $\leq z \leq$ 1.5 in the rest-frame far-ultraviolet (FUV) using HST WFC3
broadband imaging in F225W, F275W, and F336W. An analysis of 1,404 galaxies
yields 209 galaxies that host 403 kpc-scale clumps. These host galaxies appear
to be typical star-forming galaxies, with an average of 2 clumps per galaxy and
reaching a maximum of 8 clumps. We measure the photometry of the clumps, and
determine the mass, age, and star formation rates (SFR) utilizing the
SED-fitting code FAST. We find that clumps make an average contribution of 19%
to the total rest-frame FUV flux of their host galaxy. Individually, clumps
contribute a median of 5% to the host galaxy SFR and an average of $\sim$4% to
the host galaxy mass, with total clump contributions to the host galaxy stellar
mass ranging widely from less than 1% up to 93%. Clumps in the outskirts of
galaxies are typically younger, with higher star formation rates, than clumps
in the inner regions. The results are consistent with clump migration theories
in which clumps form through violent gravitational instabilities in gas-rich
turbulent disks, eventually migrate toward the center of the galaxies, and
coalesce into the bulge.