ALMA 200-parsec Resolution Imaging of Smooth Cold Dusty Disks in Typical $z \sim 3$ Star-Forming Galaxies

Understand

We present high-fidelity, 30 milliarcsecond (200-pc) resolution ALMA rest-frame 240 $\mu$m observations of cold dust emission in three typical main-sequence star-forming galaxies (SFGs) at $z \sim 3$ in the Hubble Ultra-Deep Field (HUDF).

• The cold dust is distributed within the smooth disk-like central regions of star formation $1 - 3$ kpc in diameter, despite their complex and disturbed rest-frame UV and optical morphologies.
• No dust substructures or clumps are seen down to $\simeq 1- 3$ $M_\odot$yr$^{-1}$ (1$\sigma$) per 200-pc beam.
• No dust emission is observed at the locations of UV-emitting clumps, which lie $\simeq 2-10$ kpc from the bulk of star formation.