Close-up view of a luminous star-forming galaxy at z = 2.95

Abstract

Exploiting the sensitivity of the IRAM NOrthern Extended Millimeter Array (NOEMA) and its ability to process large instantaneous bandwidths, we have studied the morphology and other properties of the molecular gas and dust in the star forming galaxy, H-ATLAS J131611.5+281219 (HerBS-89a), at z = 2.95. High angular resolution (0.?3) images reveal a partial 1.?0 diameter Einstein ring in the dust continuum emission and the molecular emission lines of 12CO(9-8) and H2O(202-111). Together with lower angular resolution (0.?6) images, we report the detection of a series of molecular lines including the three fundamental transitions of the molecular ion OH+, namely (11-01), (12-01), and (10-01), seen in absorption; the molecular ion CH+(1-0) seen in absorption, and tentatively in emission; two transitions of amidogen (NH2), namely (202-111) and (220-211) seen in emission; and HCN(11-10) and/or NH(12-01) seen in absorption. The NOEMA data are complemented with Very Large Array data tracing the 12CO(1-0) emission line, which provides a measurement of the total mass of molecular gas and an anchor for a CO excitation analysis. In addition, we present Hubble Space Telescope imaging that reveals the foreground lensing galaxy in the near-infrared (1.15 µm).