Discovery of HI gas in a young radio galaxy at z = 0.44 using the Australian square kilometre array pathfinder
Allison, JR
Sadler, EM
Moss, VA
Whiting, MT
Hunstead, RW
Pracy, MB
Curran, SJ
Croom, SM
Glowacki, M
Morganti, R
Shabala, SS
Zwaan, MA
Allen, G
Amy, SW
Axtens, P
Ball, L
Bannister, KW
Barker, S
Bell, ME
Bock, DCJ
Bolton, R
Bowen, M
Boyle, B
Braun, R
Broadhurst, S
Brodrick, D
Brothers, M
Brown, A
Bunton, JD
Cantrall, C
Chapman, J
Cheng, W
Chippendale, AP
Chung, Y
Cooray, F
Cornwell, T
DeBoer, D
Diamond, P
Edwards, PG
Ekers, R
Feain, I
Ferris, RH
Forsyth, R
Gough, R
Grancea, A
Gupta, N
Guzman, JC
Hampson, G
Harvey-Smith, L
Haskins, C
Hay, S
Hayman, DB
Heywood, I
Hotan, AW
Hoyle, S
Humphreys, B
Indermuehle, BT
Jacka, C
Jackson, C
Jackson, S
Jeganathan, K
Johnston, S
Joseph, J
Kendall, R
Kesteven, M
Kiraly, D
Koribalski, SB
Leach, M
Lenc, E
Lensson, E
Mackay, S
Macleod, A
Marquarding, M
Marvil, J
McClure-Griffiths, N
McConnell, D
Mirtschin, P
Norris, PR
Neuhold, S
Ng, A
O'Sullivan, J
Pathikulangara, J
Pearce, S
Phillips, C
Popping, A
Qiao, YR
Reynolds, EJ
Roberts, P
Sault, JR
Schinckel, A
Serra, P
Shaw, R
Shields, M
Shimwell, T
Storey, M
Sweetnam, T
Troup, E
Turner, B
Tuthill, J
Tzioumis, A
Bock, DCJ
Bolton, R
Bowen, M
Boyle, B
Braun, R
Broadhurst, S
Brodrick, D
Brothers, M
Brown, A
Bunton, JD
Cantrall, C
Chapman, J
Cheng, W
Chippendale, AP
Chung, Y
Cooray, F
Cornwell, T
DeBoer, D
Diamond, P
Edwards, PG
Ekers, R
Feain, I
Ferris, RH
Forsyth, R
Gough, R
Grancea, A
Gupta, N
Guzman, JC
Hampson, G
Harvey-Smith, L
Haskins, C
Hay, S
Hayman, DB
Heywood, I
Hotan, AW
Hoyle, S
Humphreys, B
Indermuehle, BT
Jacka, C
Jackson, C
Jackson, S
Jeganathan, K
Johnston, S
Joseph, J
Kendall, R
Kesteven, M
Kiraly, D
Koribalski, SB
Leach, M
Lenc, E
Lensson, E
Mackay, S
Macleod, A
Marquarding, M
Marvil, J
McClure-Griffiths, N
McConnell, D
Mirtschin, P
Norris, PR
Neuhold, S
Ng, A
O'Sullivan, J
Pathikulangara, J
Pearce, S
Phillips, C
Popping, A
Qiao, YR
Reynolds, EJ
Roberts, P
Sault, JR
Schinckel, A
Serra, P
Shaw, R
Shields, M
Shimwell, T
Storey, M
Sweetnam, T
Troup, E
Turner, B
Tuthill, J
Tzioumis, A
- Publication Type:
- Journal Article
- Citation:
- Monthly Notices of the Royal Astronomical Society, 2015, 453 (2), pp. 1249 - 1267
- Issue Date:
- 2015-01-01
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© 2015 The Authors. We report the discovery of a new 21-cm HI absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.5-1015.5 MHz 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 PKS B1740-517 and demonstrates ASKAP's excellent capability for performing a future wide-field survey for HI absorption at these redshifts. Optical spectroscopy and imaging using the Gemini-South telescope indicates that the HI gas is intrinsic to the host galaxy of the radio source. The narrow [OIII] emission lines show clear double-peaked structure, indicating either large-scale outflow or rotation of the ionized gas. Archival data from the XMM-Newton satellite exhibit an absorbed X-ray spectrum that is consistent with a high column density obscuring medium around the active galactic nucleus. The HI absorption profile is complex, with four distinct components ranging in width from 5 to 300 km s-1 and fractional depths from 0.2 to 20 per cent. In addition to systemic HI 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 ~ 300 km s-1. We infer that the expanding young radio source (tage ≈ 2500 yr) is cocooned within a dense medium and may be driving circumnuclear neutral gas in an outflow of ~1 M o˙ yr-1.
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