A deep ALMA image of the Hubble Ultra Deep Field

J. S. Dunlop, R. J. McLure, A. D. Biggs, J. E. Geach, M. J. Michalowski, R. J. Ivison, W. Rujopakarn, E. van Kampen, A. Kirkpatrick, A. Pope, D. Scott, A. M. Swinbank, T. A. Targett, I. Aretxaga, J. E. Austermann, P. N. Best, V. A. Bruce, E. L. Chapin, S. Charlot, M. CirasuoloK. Coppin, R. S. Ellis, S. L. Finkelstein, C. C. Hayward, D. H. Hughes, E. Ibar, P. Jagannathan, S. Khochfar, M. P. Koprowski, D. Narayanan, K. Nyland, C. Papovich, J. A. Peacock, G. H. Rieke, B. Robertson, T. Vernstrom, P. P. van der Werf, G. W. Wilson, M. Yun

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221 Citations (Scopus)

Abstract

We present the results of the first, deep Atacama Large Millimeter Array ( ALMA) imaging covering the full similar or equal to 4.5 arcmin(2) of the Hubble Ultra Deep Field ( HUDF) imaged with Wide Field Camera 3/IR on HST. Using a 45-pointing mosaic, we have obtained a homogeneous 1.3-mm image reaching sigma 1.3 similar or equal to 35 mu Jy, at a resolution of similar or equal to 0.7 arcsec. From an initial list of similar or equal to 50 > 3.5 sigma peaks, a rigorous analysis confirms 16 sources with S-1.3 > 120 mu Jy. All of these have secure galaxy counterparts with robust redshifts (< z > = 2.15). Due to the unparalleled supporting data, the physical properties of the ALMA sources are well constrained, including their stellar masses ( M-*) and UV+FIR star formation rates ( SFR). Our results show that stellar mass is the best predictor of SFR in the high-redshift Universe; indeed at z = 2 our ALMA sample contains seven of the nine galaxies in the HUDF withM(*) = 2 x 10(10)M circle dot, and we detect only one galaxy at z > 3.5, reflecting the rapid drop-off of high-mass galaxies with increasing redshift. The detections, coupled with stacking, allow us to probe the redshift/mass distribution of the 1.3-mm background down to S1.3 similar or equal to 10 mu Jy. We find strong evidence for a steep star-forming `main sequence' at z similar or equal to 2, with SFR. M* and a mean specific SFR similar or equal to 2.2 Gyr(-1). Moreover, we find that similar or equal to 85 per cent of total star formation at z similar or equal to 2 is enshrouded in dust, with similar or equal to 65 per cent of all star formation at this epoch occurring in high-mass galaxies ( M-* > 2 x 10(10)M circle dot), for which the average obscured: unobscured SF ratio is similar or equal to 200. Finally, we revisit the cosmic evolution of SFR density; we find this peaks at z similar or equal to 2.5, and that the star-forming Universe transits from primarily unobscured to primarily obscured at z similar or equal to 4.

Original languageEnglish
Pages (from-to)861-883
Number of pages23
JournalMonthly Notices of the Royal Astronomical Society
Volume466
Issue number1
DOIs
Publication statusPublished - Apr 2017
Externally publishedYes

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