Discovery of HI gas in a young radio galaxy at $z = 0.44$ using the Australian Square Kilometre Array Pathfinder
| Autor: | Allison, J. R., Sadler, E. M., Moss, V. A., Whiting, M. T., Hunstead, R. W., Pracy, M. B., Curran, S. J., Croom, S. M., Glowacki, M., Morganti, R., Shabala, S. S., Zwaan, M. A., Allen, G., Amy, S. W., Axtens, P., Ball, L., Bannister, K. W., Barker, S., Bell, M. E., Bock, D. C. -J., Bolton, R., Bowen, M., Boyle, B., Braun, R., Broadhurst, S., Brodrick, D., Brothers, M., Brown, A., Bunton, J. D., Cantrall, C., Chapman, J., Cheng, W., Chippendale, A. P., Chung, Y., Cooray, F., Cornwell, T., DeBoer, D., Diamond, P., Edwards, P. G., Ekers, R., Feain, I., Ferris, R. H., Forsyth, R., Gough, R., Grancea, A., Gupta, N., Guzman, J. C., Hampson, G., Harvey-Smith, L., Haskins, C., Hay, S., Hayman, D. B., Heywood, I., Hotan, A. W., Hoyle, S., Humphreys, B., Indermuehle, B. T., Jacka, C., Jackson, C., Jackson, S., Jeganathan, K., Johnston, S., Joseph, J., Kendall, R., Kesteven, M., Kiraly, D., Koribalski, B. S., Leach, M., Lenc, E., Lensson, E., Mackay, S., Macleod, A., Marquarding, M., Marvil, J., McClure-Griffiths, N., McConnell, D., Mirtschin, P., Norris, R. P., Neuhold, S., Ng, A., O'Sullivan, J., Pathikulangara, J., Pearce, S., Phillips, C., Popping, A., Qiao, R. Y., Reynolds, J. E., Roberts, P., Sault, R. J., Schinckel, A., Serra, P., Shaw, R., Shields, M., Shimwell, T., Storey, M., Sweetnam, T., Troup, E., Turner, B., Tuthill, J., Tzioumis, A., Voronkov, M. A., Westmeier, T., Wilson, C. D. |
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| Rok vydání: | 2015 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/mnras/stv1532 |
| Popis: | 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$-$517 and demonstrates ASKAP's excellent capability for performing a future wide-field survey for HI absorption at these redshifts. Optical spectroscopy and imaging using the Gemini-South telescope indicates that the HI gas is intrinsic to the host galaxy of the radio source. The narrow OIII emission lines show clear double-peaked structure, indicating either large-scale outflow or rotation of the ionized gas. Archival data from the \emph{XMM-Newton} satellite exhibit an absorbed X-ray spectrum that is consistent with a high column density obscuring medium around the active galactic nucleus. The HI absorption profile is complex, with four distinct components ranging in width from 5 to 300 km s$^{-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 $v \sim 300$ km s$^{-1}$. We infer that the expanding young radio source ($t_{\rm age} \approx 2500$ yr) is cocooned within a dense medium and may be driving circumnuclear neutral gas in an outflow of $\sim$ 1 $\mathrm{M}_{\odot}$ yr$^{-1}$. Comment: 18 pages, 11 figures, accepted for publication in MNRAS |
| Databáze: | arXiv |
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