First redshift determination of an optically/UV faint submillimeter galaxy using CO emission lines

TL;DR

This paper reports the first precise redshift measurement of a faint submillimeter galaxy using CO emission lines, demonstrating a method that will become standard with future ALMA observations.

Contribution

It presents the first redshift determination of an optically/UV faint SMG using CO lines with the IRAM 30m telescope, showcasing a new approach for distant galaxy studies.

Findings

Redshift of SMMJ14009+0252 determined to be z=2.9344

Successful detection of CO(3--2) and CO(5--4) lines

Method poised to become routine with ALMA

Abstract

We report the redshift of a distant, highly obscured submm galaxy (SMG), based entirely on the detection of its CO line emission. We have used the newly commissioned Eight-MIxer Receiver (EMIR) at the IRAM 30m telescope, with its 8 GHz of instantaneous dual-polarization bandwidth, to search the 3-mm atmospheric window for CO emission from SMMJ14009+0252, a bright SMG detected in the SCUBA Lens Survey. A detection of the CO(3--2) line in the 3-mm window was confirmed via observations of CO(5--4) in the 2-mm window. Both lines constrain the redshift of SMMJ14009+0252 to z=2.9344, with high precision (dz=2 10^{-4}). Such observations will become routine in determining redshifts in the era of the Atacama Large Millimeter/submillimeter Array (ALMA).