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

TL;DR

This study reports redshift measurements for three bright submillimeter galaxies near GOODS-N, revealing their high star formation rates, gas content, and potential protocluster environment at high redshift.

Contribution

First spectroscopic redshift measurements of bright SMGs near GOODS-N using NOEMA, identifying a possible high-redshift protocluster environment.

Findings

Two galaxies at z ~ 3.14 with high SFRs and gas masses.

One galaxy at z = 4.42 with even higher SFR.

Evidence of a protocluster of SMGs and optical sources.

Abstract

We report spectroscopic redshift measurements for three bright submillimeter galaxies (SMGs) near the GOODS-N field, each with SCUBA-2 850 micron fluxes > 10 mJy, using the Northern Extended Millimeter Array (NOEMA). Our molecular linescan observations of these sources, which occupy a ~7 arcmin$^2$ area outside of the HST coverage of the field, reveal that two lie at $z \sim$ 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 SFRs $\sim4000 ~{\rm M_{\odot}~yr^{-1}}$ in the $z$ = 4.42 galaxy and $\sim 2500~{\rm M_{\odot}~yr^{-1}}$ in the two $z \sim$ 3.14 galaxies. Based on our sources' CO line luminosities, we estimate $M_{{\rm gas}}\sim10^{11} M_{\odot}$ and find gas depletion timescales of $\tau_{{\rm depl}}\sim 50$ Myr, consistent with findings in other high-redshift SMGs. Finally, we show that the two $z \sim$ 3.14 sources, which alone occupy a volume $\sim$10 Mpc$^3$, very likely mark the location of a protocluster of bright SMGs and less dusty optical sources.