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Discovery of H ɪ gas in a young radio galaxy at z = 0.44 using the Australian Square Kilometre Array Pathfinder


Allison, JR and Sadler, EM and Moss, VA and Whiting, MT and Hunstead, RW and Pracy, MB and Curran, SJ and Croom, SM and Glowacki, M and Morganti, R and Shabala, SS and Zwaan, MA and Allen, G and Amy, SW and Axtens, P and Ball, L and Bannister, KW and Barker, S and Bell, ME and Bock, DC-J and Bolton, R and Bowen, M and Boyle, B and Braun, R and Broadhurst, S and Brodrick, D and Brothers, M and Brown, A and Bunton, JD and Cantrall, C and Chapman, J and Cheng, W and Chippendale, AP and Chung, Y and Cooray, F and Cornwell, T and DeBoer, D and Diamond, P and Edwards, PG and Ekers, R and Feain, I and Ferris, RH and Forsyth, R and Gough, R and Grancea, A and Gupta, N and Guzman, JC and Hampson, G and Harvey-Smith, L and Haskins, C and Hay, S and Hayman, DB and Heywood, I and Hotan, AW and Hoyle, S and Humphreys, B and Indermuehle, BT and Jacka, C and Jackson, C and Jackson, S and Jeganathan, K and Johnston, S and Joseph, J and Kendall, R and Kesteven, M and Kiraly, D and Koribalski, BS and Leach, M and Lenc, E and Lensson, E and Mackay, S and Macleod, A and Marquarding, M and Marvil, J and McClure-Griffiths, N and McConnell, D and Mirtschin, P and Norris, RP and Neuhold, S and Ng, A and O'Sullivan, J and Pathikulangara, J and Pearce, S and Phillips, C and Popping, A and Qiao, RY and Reynolds, JE and Roberts, P and Sault, RJ and Schinckel, A and Serra, P and Shaw, R and Shields, M and Shimwell, T and Storey, M and Sweetnam, T and Troup, E and Turner, B and Tuthill, J and Tzioumis, A and Voronkov, MA and Westmeier, T and Wilson, CD, Discovery of H ɪ gas in a young radio galaxy at z = 0.44 using the Australian Square Kilometre Array Pathfinder, Monthly Notices of the Royal Astronomical Society, 453, (2) pp. 1249-1267. ISSN 0035-8711 (2015) [Refereed Article]

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This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society : 2015 the authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

DOI: doi:10.1093/mnras/stv1532


We report the discovery of a new 21-cm H i absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.51015.5MHz band of ASKAP we were able to conduct a blind search for the 21-cm line in a continuous redshift range between z=0.4 and 1.0, which has, until now, remained largely unexplored. The absorption line is detected at z=0.44 towards the GHz-peaked spectrum radio source PKSB1740−517 and demonstrates ASKAP's excellent capability for performing a future wide-field survey for H i absorption at these redshifts. Optical spectroscopy and imaging using the Gemini-South telescope indicates that the H i gas is intrinsic to the host galaxy of the radio source. The narrow [O iii] emission lines show clear double-peaked structure, indicating either large-scale outflow or rotation of the ionized gas. Archival data from the XMMNewton satellite exhibit an absorbed X-ray spectrum that is consistent with a high column density obscuring medium around the active galactic nucleus. The H i absorption profile is complex, with four distinct components ranging in width from 5 to 300kms−1 and fractional depths from 0.2 to 20 per cent. In addition to systemic H i gas, in a circumnuclear disc or ring structure aligned with the radio jet, we find evidence for a possible broad outflow of neutral gas moving at a radial velocity of v∼300kms−1. We infer that the expanding young radio source (tage≈2500yr) is cocooned within a dense medium and may be driving circumnuclear neutral gas in an outflow of ∼1Myr−1.

DOI for Erratum: doi:10.1093/mnras/stv2908

Item Details

Item Type:Refereed Article
Keywords:methods: data analysis, ISM: jets and outflows, galaxies: active, galaxies: ISM, radio lines: galaxies
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Shabala, SS (Associate Professor Stas Shabala)
ID Code:102556
Year Published:2015
Funding Support:Australian Research Council (DE130101399)
Web of Science® Times Cited:58
Deposited By:Mathematics and Physics
Deposited On:2015-08-28
Last Modified:2017-11-03
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