Abstract
We present $\simeq$0$.\!\!^{\prime\prime}4$-resolution
extinction-independent distributions of star formation and dust in 11
star-forming galaxies (SFGs) at $z = 1.3-3.0$. These galaxies are
selected from sensitive, blank-field surveys of the $2' \times 2'$
Hubble Ultra-Deep Field at $\lambda = 5$ cm and 1.3 mm using the Karl G.
Jansky Very Large Array (VLA) and Atacama Large Millimeter/submillimeter
Array (ALMA). They have star-formation rates (SFRs), stellar masses, and
dust properties representative of massive main-sequence SFGs at $z \sim
2$. 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 active galactic nuclei (AGN),
thereby representing a diversity of $z \sim 2$ SFGs undergoing vigorous
mass assembly. 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
diameter of $4.2 \pm 1.8$ kpc. This provides direct evidence for
galaxy-wide star formation in distant, blank-field-selected
main-sequence SFGs. The typical galactic-average SFR surface density is
2.5 M$_{\odot}$yr$^{-1}$kpc$^{-2}$, sufficiently high to drive outflows.
In X-ray-selected AGN where radio emission is enhanced over the level
associated with star formation, the radio excess pinpoints the AGN,
which are found to be co-spatial with star formation. The median
extinction-independent size of main-sequence SFGs is two times larger
than those of bright submillimeter galaxies whose SFRs are $3-8$ times
larger, providing a constraint on the characteristic SFR ($\sim300$
M$_{\odot}$yr$^{-1}$) above which a significant population of more
compact star-forming galaxies appears to emerge.
Original language | English |
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Journal | Astrophysical Journal |
Volume | 833 |
Issue number | 1 |
Publication status | Published - 1 Dec 2016 |
Keywords / Materials (for Non-textual outputs)
- Astrophysics - Astrophysics of Galaxies
- Astrophysics - Cosmology and Nongalactic Astrophysics