VLA and ALMA Imaging of Intense, Galaxy-Wide Star Formation in z ~ 2 Galaxies

W. Rujopakarn, J. S. Dunlop, G. H. Rieke, R. J. Ivison, A. Cibinel, K. Nyland, P. Jagannathan, J. D. Silverman, D. M. Alexander, A. D. Biggs, S. Bhatnagar, D. R. Ballantyne, M. Dickinson, D. Elbaz, J. E. Geach, C. C. Hayward, A. Kirkpatrick, R. J. McLure, M. J. Michalowski, N. A. MillerD. Narayanan, F. N. Owen, M. Pannella, C. Papovich, A. Pope, U. Rau, B. E. Robertson, D. Scott, A. M. Swinbank, P. van der Werf, E. van Kampen, B. J. Weiner, R. A. Windhorst

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

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 languageEnglish
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 1 Dec 2016

Keywords / Materials (for Non-textual outputs)

  • Astrophysics - Astrophysics of Galaxies
  • Astrophysics - Cosmology and Nongalactic Astrophysics


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