Dynamical Structure of the Molecular Interstellar Medium in an Extremely Bright, Multiply Lensed z ~= 3 Submillimeter Galaxy Discovered with Herschel

Riechers, Dominik A. and Cooray, A. and Omont, A. and Neri, R. and Harris, A. I. and Baker, A. J. and Cox, P. and Frayer, D. T. and Carpenter, J. M. and Auld, R. and Aussel, H. and Beelen, A. and Blundell, R. and Bock, J. and Brisbin, D. and Burgarella, D. and Chanial, P. and Chapman, S. C. and Clements, D. L. and Conley, A. and Dowell, C. D. and Eales, S. and Farrah, D. and Franceschini, A. and Gavazzi, R. and Glenn, J. and Griffin, M. and Gurwell, M. and Ivison, R. J. and Kim, S. and Krips, M. and Mortier, A. M. J. and Oliver, S. J. and Page, M. J. and Papageorgiou, A. and Pearson, C. P. and Pérez-Fournon, I. and Pohlen, M. and Rawlings, J. I. and Raymond, G. and Rodighiero, G. and Roseboom, I. G. and Rowan-Robinson, M. and Scott, K. S. and Seymour, N. and Smith, A. J. and Symeonidis, M. and Tugwell, K. E. and Vaccari, M. and Vieira, J. D. and Vigroux, L. and Wang, L. and Wardlow, J. and Wright, G. (2011) Dynamical Structure of the Molecular Interstellar Medium in an Extremely Bright, Multiply Lensed z ~= 3 Submillimeter Galaxy Discovered with Herschel. Astrophysical Journal Letters, 733 (1). ISSN 2041-8205

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We report the detection of CO(J = 5 → 4), CO(J = 3 → 2), and CO(J = 1 → 0) emission in the strongly lensed, Herschel/SPIRE-selected submillimeter galaxy (SMG) HERMES J105751.1+573027 at z = 2.9574 ± 0.0001, using the Plateau de Bure Interferometer, the Combined Array for Research in Millimeter-wave Astronomy, and the Green Bank Telescope. The observations spatially resolve the molecular gas into four lensed images with a maximum separation of ~9'' and reveal the internal gas dynamics in this system. We derive lensing-corrected CO line luminosities of L'CO(1-0) = (4.17 ± 0.41), L'CO(3-2) = (3.96 ± 0.20), and L'CO(5-4) = (3.45 ± 0.20) × 1010 (μL/10.9)-1 K km s-1 pc2, corresponding to luminosity ratios of r 31 = 0.95 ± 0.10, r 53 = 0.87 ± 0.06, and r 51 = 0.83 ± 0.09. This suggests a total molecular gas mass of M gas = 3.3×1010 (αCO/0.8) (μL/10.9)-1 M sun. The gas mass, gas mass fraction, gas depletion timescale, star formation efficiency, and specific star formation rate are typical for an SMG. The velocity structure of the gas reservoir suggests that the brightest two lensed images are dynamically resolved projections of the same dust-obscured region in the galaxy that are kinematically offset from the unresolved fainter images. The resolved kinematics appear consistent with the complex velocity structure observed in major, "wet" (i.e., gas-rich) mergers. Major mergers are commonly observed in SMGs and are likely to be responsible for fueling their intense starbursts at high gas consumption rates. This study demonstrates the level of detail to which galaxies in the early universe can be studied by utilizing the increase in effective spatial resolution and sensitivity provided by gravitational lensing.

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Journal Article
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Astrophysical Journal Letters
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07 Nov 2018 13:30
Last Modified:
01 Dec 2020 06:18