NOEMA Redshift Measurements of Extremely Bright Submillimeter Galaxies near the GOODS-N

We report spectroscopic redshift measurements for three bright submillimeter galaxies (SMGs) near the GOODS-N field, each with SCUBA-2 850 μm fluxes >10 mJy, using the Northern Extended Millimeter Array (NOEMA). Our molecular line-scan observations of these sources, which occupy an ~7 arcmin² area outside of the Hubble Space Telescope coverage of the field, reveal that two lie at z ~ 3.14. In the remaining object, we detect line emission consistent with CO(7-6), [C I], and H₂O at z = 4.42. The far-infrared spectral energy distributions of these galaxies, constrained by SCUBA-2, NOEMA, and Herschel/SPIRE, indicate instantaneous star formation rates ~4000 M_⊙ yr^-1 in the z = 4.42 galaxy and ~2500 M_⊙ yr^-1 in the two z ~ 3.14 galaxies. Based on the sources' CO line luminosities, we estimate M_gas ~ 10¹¹M_⊙ and find gas depletion timescales of τ_depl ~ 50 Myr, consistent with findings in other high-redshift SMGs. Finally, we show that the two z ~ 3.14 sources, which alone occupy a volume ~10 Mpc³, very likely mark the location of a protocluster of bright SMGs and less-dusty optical sources.