The Einstein ring GAL-CLUS-022058s: a Lensed Ultrabright Submillimeter Galaxy at z=1.4796

Abstract

We report an ultra-bright lensed submillimeter galaxy at zspec = 1:4796, identi_ed as a result of a full-sky cross-correlation of the AllWISE and Planck compact source catalogs aimed to search for bright submillimeter galaxies at z _ 1:5 ð€€€ 2:8. APEX/LABOCA observations of the candidate Galaxy reveal a source with ux (S870_m = 54_8 mJy). The position of the APEX source coincides with the position of the AllWISE mid-IR source, and with the Einstein ring GAL-CLUS-022058s, observed with the HST. Archival VLT/FORS observations reveal the redshift of this Einstein ring, zspec = 1:4796, and detection of the CO(5-4) line at zspec = 1:4802 with APEX/nFLASH230 con_rms the redshift of the submillimeter emission. The lensed source appears to be gravitationally magni_ed by a massive foreground galaxy cluster lens at z = 0:36. We use Lenstool to model the gravitational lensing, which is near to a \fold arc" con_guration for an elliptical mass distribution of the central halo, where four images of the lensed galaxy are seen; the mean magni_cation is _L = 18 _ 4. We have determined an intrinsic rest-frame infrared luminosity of LIR _ 1012L_ and a likely star formation rate of _ 70 ð€€€ 170 M_ yrð€€€1. The molecular gas mass is Mmol _ 2:6 _ 1010M_ and the gas fraction is f = 0:34 _ 0:07. We also obtain a stellar mass log(M_=M_) = 10:7 _ 0:1 and a speci_c star formation rate log(sSFR=Gyrð€€€1) = 0:15 _ 0:03. This galaxy lies on the so-called main sequence of star-forming galaxies at this redshift.