Artikel i vetenskaplig tidskrift, 2015

We present high-resolution 870 μm Atacama Large Millimeter/sub-millimeter Array (ALMA) continuum maps of 30 bright sub-millimeter sources in the UKIDSS UDS field. These sources are selected from deep, 1 degree2 850 μm maps from the SCUBA-2 Cosmology Legacy Survey, and are representative of the brightest sources in the field (median SSCUBA-2= 8.7 ± 0.4 mJy). We detect 52 sub-millimeter galaxies (SMGs) at >4σ significance in our 30 ALMA maps. In 61-15+19% of the ALMA maps the single-dish source comprises a blend of ≥2 SMGs, where the secondary SMGs are Ultra-luminous Infrared Galaxies (ULIRGs) with LIR ≳ 1012 L⊙. The brightest SMG contributes on average 80-2+6% of the single-dish flux density, and in the ALMA maps containing ≥2 SMGs the secondary SMG contributes 25-5+1% of the integrated ALMA flux. We construct source counts and show that multiplicity boosts the apparent single-dish cumulative counts by 20% at S870 > 7.5 mJy, and by 60% at S870 > 12 mJy. We combine our sample with previous ALMA studies of fainter SMGs and show that the counts are well-described by a double power law with a break at 8.5 ± 0.6 mJy. The break corresponds to a luminosity of ∼6 × 1012 L⊙ or a star formation rate (SFR) of ∼103 M⊙ yr-1. For the typical sizes of these SMGs, which are resolved in our ALMA data with Re = 1.2 ± 0.1 kpc, this yields a limiting SFR density of ∼100 M⊙ yr-1 kpc-2 Finally, the number density of S870 ≳ 2 mJy SMGs is 80 ± 30 times higher than that derived from blank-field counts. An over-abundance of faint SMGs is inconsistent with line-of-sight projections dominating multiplicity in the brightest SMGs, and indicates that a significant proportion of these high-redshift ULIRGs are likely to be physically associated.

galaxies: starburst

submillimeter: galaxies

galaxies: abundances

galaxies: high-redshift

galaxies: star formation


J. M. Simpson

Durham University

I. Smail

Durham University

A.M. Swinbank

Durham University

S.C. Chapman

Dalhousie University

J.E. Geach

University of Hertfordshire

R.J. Ivison

University of Edinburgh

European Southern Observatory (ESO)

A. P. Thomson

Durham University

I. Aretxaga

Instituto Nacional de Astrofísica, Óptica y Electrońica

A.W. Blain

University Of Leicester

W.I. Cowley

Durham University

C. C. Chen

Durham University

K. E. K. Coppin

University of Hertfordshire

J.S. Dunlop

University of Edinburgh

A. C. Edge

Durham University

D. Farrah

Virginia Polytechnic Institute and State University

E. Ibar

Universidad de Valparaíso

A. Karim

Universität Bonn

Kirsten Kraiberg Knudsen

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

R. Meijerink

Universiteit Leiden

M. J. Michalowski

University of Edinburgh

D. Scott

University of British Columbia (UBC)

M. Spaans

Rijksuniversiteit Groningen

P.P. van der Werf

Universiteit Leiden

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 807 2 128


Astronomi, astrofysik och kosmologi


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