ALMA and JVLA imaging of intense galaxy-wide star formation in z ~ 2 galaxies in the HUDF: bridging SMGs to the Main Sequence

We present ~0.4'' resolution extinction-independent distributions of star formation and dust in 11 main-sequence star-forming galaxies (SFGs) at z ~ 2. These galaxies are selected from deep ALMA and JVLA surveys of the Hubble Ultra-Deep Field at 1.3 mm and 5 cm. Morphological classification performed on spatially-resolved stellar mass maps indicates a mixture of disk and morphologically disturbed systems; half of the sample harbor X-ray AGN. We find that their intense star formation most frequently occurs at the location of stellar-mass concentration and extends over an area comparable to their stellar-mass distribution, with a median r_e = 2.4 kpc, thereby providing direct evidence of galaxy-wide star formation in z ~ 2 main-sequence SFGs. In X-ray AGN where radio emission is enhanced over the level associated with star formation, the radio excess pinpoints the AGN, which are found to be cospatial with star formation. The median extinction-independent size of main-sequence SFGs is 2x larger than those of luminous SMGs, providing a constraint on the characteristic SFR of ~300 Msun/yr above which a significant population of more compact SFGs appears to emerge, possibly bridging the populations of SMGs to main-sequence SFGs