Alma 1.3 Mm Survey Of Lensed Submillimeter Galaxies Selected By Herschel: Discovery Of Spatially Extended Smgs And Implications

We present an ALMA 1.3 mm (Band 6) continuum survey of lensed submillimeter galaxies (SMGs) at z = 1.0 to similar to 3.2 with an angular resolution of similar to 02. These galaxies were uncovered by the Herschel Lensing Survey and feature exceptionally bright far-infrared continuum emission (S-peak greater than or similar to 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 mu m) 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 (R-e,R-dust/R-e,R-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 (less than or similar to 0.1 mJy arcsec(-2)), in which the star formation is distributed over the entire galaxy (R-e,R-dust/R-e,R-star > 1). As a whole, our SMG sample shows a tight anticorrelation between (R-e,R-dust/R-e,R-star) and far-infrared surface brightness (sigma(IR)) over a factor of 1000 in sigma(IR). This indicates that SMGs with less vigorous star formation (i.e., lower sigma(IR)) lack central starburst and are likely to retain a broader spatial distribution of star formation over the whole galaxies (i.e., larger R-e,R-dust/R-e,R-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 similar to 2.