# Physical Properties of Sub-galactic Clumps at 0.5 $\leq z \leq$ 1.5 in the UVUDF

## TL;DR

This study analyzes the properties of star-forming clumps in galaxies at redshifts 0.5 to 1.5 using HST UV imaging, revealing insights into their contribution to galaxy evolution and support for clump migration theories.

## Contribution

First detailed analysis of UV-bright clumps in galaxies at intermediate redshifts, linking their properties to galaxy evolution models.

## Key findings

- Clumps contribute about 19% to the host galaxy's UV flux.
- Clumps account for a median of 5% of the galaxy's SFR.
- Clumps in outer regions are younger and more active.

## 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.