ALMA 1.3 mm Survey of Lensed Submillimeter Galaxies Selected by Herschel: Discovery of Spatially Extended SMGs and Implications

February 2021 • 2021ApJ...908..192S

Authors • Sun, Fengwu • Egami, Eiichi • Rawle, Timothy D. • Walth, Gregory L. • Smail, Ian • Dessauges-Zavadsky, Miroslava • Pérez-González, Pablo G. • Richard, Johan • Combes, Francoise • Ebeling, Harald • Pelló, Roser • Van der Werf, Paul • Altieri, Bruno • Boone, Frédéric • Cava, Antonio • Chapman, Scott C. • Clément, Benjamin • Finoguenov, Alexis • Nakajima, Kimihiko • Rujopakarn, Wiphu • Schaerer, Daniel • Valtchanov, Ivan

Abstract • We present an ALMA 1.3 mm (Band 6) continuum survey of lensed submillimeter galaxies (SMGs) at z = 1.0 to ∼3.2 with an angular resolution of ∼0"2. These galaxies were uncovered by the Herschel Lensing Survey and feature exceptionally bright far-infrared continuum emission (Speak ≳ 90 mJy) owing to their lensing magnification. We detect 29 sources in 20 fields of massive galaxy clusters with ALMA. Using both the Spitzer/IRAC (3.6/4.5 μm) and ALMA data, we have successfully modeled the surface brightness profiles of 26 sources in the rest-frame near- and far-infrared. Similar to previous studies, we find the median dust-to-stellar continuum size ratio to be small (Re,dust/Re,star = 0.38 ± 0.14) for the observed SMGs, indicating that star formation is centrally concentrated. This is, however, not the case for two spatially extended main-sequence SMGs with a low surface brightness at 1.3 mm (≲0.1 mJy arcsec-2), in which the star formation is distributed over the entire galaxy (Re,dust/Re,star > 1). As a whole, our SMG sample shows a tight anticorrelation between (Re,dust/Re,star) and far-infrared surface brightness (ΣIR) over a factor of ≃1000 in ΣIR. This indicates that SMGs with less vigorous star formation (i.e., lower ΣIR) lack central starburst and are likely to retain a broader spatial distribution of star formation over the whole galaxies (i.e., larger Re,dust/Re,star). The same trend can be reproduced with cosmological simulations as a result of central starburst and potentially subsequent "inside-out" quenching, which likely accounts for the emergence of compact quiescent galaxies at z ∼ 2.


IPAC Authors


Greg Walth

Assistant Scientist