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The Discovery of a New Massive Molecular Gas Component Associated with the Submillimeter Galaxy SMM J02399-0136

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posted on 07.11.2018, 11:40 by David T. Frayer, Ronald J. Maddalena, R. J. Ivison, Ian Smail, Andrew W. Blain, Paul Vanden Bout
We present CO(1–0), CO(3–2), and CO(7–6) observations using the Green Bank Telescope (GBT) and the Atacama Large Millimeter Array (ALMA) of the z = 2.8 submillimeter galaxy SMM J02399−0136. This was the first submillimeter-selected galaxy discovered and remains an archetype of the class, comprising a merger of several massive and active components, including a quasar-luminosity AGN and a highly obscured, gas-rich starburst spread over a ~25 kpc extent. The GBT CO(1–0) line profile is comprised of two distinct velocity components separated by about 600 km s−1 and suggests the presence of a new component of molecular gas that had not been previously identified. The CO(3–2) observations with ALMA show that this new component, designated W1, is associated with a large extended structure stretching 13 kpc westward from the AGN. W1 is not detected in the ALMA CO(7–6) data, implying that this gas has much lower CO excitation than the central starburst regions, which are bright in CO(7–6). The molecular gas mass of W1 is about 30% of the total molecular gas mass in the system, depending on the CO-to-H2 conversion factor. W1 is arguably a merger remnant; alternatively, it could be a massive molecular outflow associated with the AGN, or perhaps inflowing metal-enriched molecular gas fueling the ongoing activity.


We thank our colleagues at the Green Bank Observatory, who have made these observations possible. We greatly appreciate the staff at the North American ALMA Science Center, who calibrated the raw ALMA visibilities. The Green Bank Observatory and the National Radio Astronomy Observatory are facilities of the National Science Foundation operated under cooperative agreements by Associated Universities, Inc. This paper makes use of the following ALMA data: ADS/JAO.ALMA #2013.1.00403.S, ADS/JAO.ALMA #2015.1.00302.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The optical image is based on observations obtained with the NASA/ESA Hubble Space Telescope, retrieved from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute (STScI). STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. R.J.I. acknowledges ERC funding in the form of Advance Grant COSMICISM (321302). I.R.S. acknowledges support from the ERC Advance Grant DUSTYGAL (321334), a Royal Society/Wolfson Award, and STFC(ST/P000541/1).



Astrophysical Journal, 2018, 860 (2), pg. 87 (7)

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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American Astronomical Society, IOP Publishing





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Facilities: GBT - Green Bank Telescope, ALMA. - Software: RADEX (van der Tak et al. 2007), GBTIDL (Marganian et al. 2006), CASA (McMullin et al. 2007).