HerMES: ALMA imaging of Herschel-selected dusty star-forming galaxies

Bussmann, R S, Riechers, D, Fialkov, A, Scudder, J, Hayward, C C, Cowley, W I, Bock, J, Calanog, J, Chapman, S C, Cooray, A, De Bernardis, F, Farrah, D, Fu, Hai, Gavazzi, R, Hopwood, R, Ivison, R J, Jarvis, M, Lacey, C, Loeb, A, Oliver, S J, Pérez-Fournon, I, Rigopoulou, D, Roseboom, I J, Scott, Douglas, Smith, A J, Vieira, J D, Wang, L and Wardlow, J (2015) HerMES: ALMA imaging of Herschel-selected dusty star-forming galaxies. The Astrophysical Journal, 812 (1). ISSN 1538-4357

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The Herschel Multi-tiered Extragalactic Survey (HerMES) has identified large numbers of dusty star-forming galaxies (DSFGs) over a wide range in redshift. A detailed understanding of these DSFGs is hampered by the limited spatial resolution of Herschel. We present 870 µm 0.0045 resolution imaging from the Atacama Large Millimeter/submillimeter Array (ALMA) of 29 HerMES DSFGs with farinfrared (FIR) flux densities in between the brightest of sources found by Herschel and fainter DSFGs
found in ground-based sub-millimeter (sub-mm) surveys. We identify 62 sources down to the 5σ point-source sensitivity limit in our ALMA sample (σ ≈ 0.2 mJy), of which 6 are strongly lensed (showing multiple images) and 36 experience significant amplification (µ > 1.1). To characterize the properties of the ALMA sources, we introduce and make use of uvmcmcfit, a publicly available
Markov chain Monte Carlo analysis tool for interferometric observations of lensed galaxies. Our lens
models tentatively favor intrinsic number counts for DSFGs with a steep fall off above 8 mJy at 880 µm. Nearly 70% of the Herschel sources comprise multiple ALMA counterparts, consistent with previous research indicating that the multiplicity rate is high in bright sub-mm sources. Our ALMA sources are located significantly closer to each other than expected based on results from theoretical models as well as fainter DSFGs identified in the LABOCA ECDFS Submillimeter Survey. The high multiplicity rate and low projected separations argue in favor of interactions and mergers driving the
prodigious emission from the brightest DSFGs as well as the sharp downturn above S880 = 8 mJy.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
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Depositing User: Nikoleta Kiapidou
Date Deposited: 20 Apr 2016 09:25
Last Modified: 02 Sep 2017 03:36

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