Close-up view of a luminous star-forming galaxy at z=2.95
Abstract
(Abridged) Exploiting the sensitivity and broad band width of NOEMA, we have studied the molecular gas and dust in the galaxy HerBS-89a, at z=2.95. High angular resolution 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(2_02-1_11). We report the detection of the three fundamental transitions of the molecular ion OH+, seen in absorption; the molecular ion CH+(1-0) seen in absorption (and tentatively in emission); two transitions of amidogen (NH2), seen in emission; and HCN(11-10) and/or NH(1_2-0_1) seen in absorption. The NOEMA data are complemented with VLA 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 HST imaging that reveals the foreground lensing galaxy in the near-infrared. Together with data from the GTC, we derive a photometric redshift of z(phot)~0.9 for the foreground lensing galaxy. Modelling the lensing of HerBS-89a, we reconstruct the dust continuum and molecular emission lines (magnified by a factor ~4-5) in the source plane. The 12CO(9-8) and H2O emission lines have comparable spatial and kinematic distributions; the source-plane reconstructions do not clearly distinguish between a one-component and a two-component scenario, but the latter accounts for the observed broad line widths. HerBS-89a is a powerful star forming galaxy with a dust-to-gas ratio delta(GDR)~80, a SFR = 614 +/- 59 Msun/yr and a depletion timescale tau(depl) = (3.4 +/- 1.0) 1e8 years. The OH+ and CH+ absorption lines, all have their main velocity component red-shifted by \Delta(V)~100 km/s relative to the global CO reservoir. We argue that these absorption lines trace a rare example of gas inflow towards the center of the galaxy.
Keywords
Cite
@article{arxiv.2012.01448,
title = {Close-up view of a luminous star-forming galaxy at z=2.95},
author = {S. Berta and A. J. Young and P. Cox and R. Neri and B. M. Jones and A. J. Baker and A. Omont and L. Dunne and A. Carnero Rosell and L. Marchetti and M. Negrello and C. Yang and D. A. Riechers and H. Dannerbauer and I. Perez-Fournon and P. van der Werf and T. Bakx and R. J. Ivison and A. Beelen and V. Buat and A. Cooray and I. Cortzen and S. Dye and S. Eales and R. Gavazzi and A. I. Harris and C. N. Herrera and D. Hughes and S. Jin and M. Krips and G. Lagache and M. Lehnert and H. Messias and S. Serjeant and F. Stanley and S. Urquhart and C. Vlahakis and A. Weiss},
journal= {arXiv preprint arXiv:2012.01448},
year = {2021}
}
Comments
33 pages, Accepted for publication on A&A