The large-scale distribution of neutral hydrogen in the Fornax region
Authors: Meryl Waugh1; M. J. Drinkwater1; R. L. Webster1; L. Staveley-Smith2; V. A. Kilborn3; D. G. Barnes4; R. Bhathal5; W. J. G. de Blok2; P. J. Boyce6; M. J. Disney6; R. D. Ekers2; K. C. Freeman7; B. K. Gibson4; P. A. Henning8; H. Jerjen7; P. M. Knezek9; B. Koribalski2; M. Marquarding2; R. F. Minchin6; R. M. Price8; M. E. Putman10; S. D. Ryder11; E. M. Sadler12; F. Stootman5; M. A. Zwaan1
Source: Monthly Notices of the Royal Astronomical Society, Volume 337, Number 2, December 2002 , pp. 641-656(16)
Publisher: Blackwell Publishing
- Free Content
- New Content
- Subscribed Content
- Free Trial Content
Abstract:
Using data from the H i Parkes All Sky Survey (HIPASS), we have searched for neutral hydrogen in galaxies in a region
25 × 25 deg2 centred on NGC 1399, the nominal centre of the Fornax cluster. Within a velocity search range of 300–3700 km s-1 and to a 3
lower flux limit of 40 mJy, 110 galaxies with H i emission were detected, one of which is previously uncatalogued. None of the detections has early-type morphology. Previously unknown velocities for 14 galaxies have been determined, with a further four velocity measurements being significantly dissimilar to published values. Identification of an optical counterpart is relatively unambiguous for more than 90 per cent of our H i galaxies. The galaxies appear to be embedded in a sheet at the cluster velocity which extends for more than 30° across the search area. At the nominal cluster distance of 20 Mpc, this corresponds to an elongated structure more than 10 Mpc in extent. A velocity gradient across the structure is detected, with radial velocities increasing by 500 km s-1 from south-east to north-west. The clustering of galaxies evident in optical surveys is only weakly suggested in the spatial distribution of our H i detections. Of 62 H i detections within a 10° projected radius of the cluster centre, only two are within the core region (projected radius <1°) and less than 30 per cent are within 3.5°, suggesting a considerable deficit of H i-rich galaxies in the centre of the cluster. However, relative to the field, there is a 3(±1)-fold excess of H i-rich galaxies in the outer parts of the cluster where galaxies may be infalling towards the cluster for the first time.
Keywords: surveys; galaxies: clusters: individual: Fornax; galaxies: evolution; large-scale structure of Universe; radio lines: galaxies
Document Type: Research article
DOI: 10.1046/j.1365-8711.2002.05942.x
Affiliations: 1: School of Physics, University of Melbourne, VIC 3010, Australia 10: Centre for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389, USA 11: Anglo-Australian Observatory, PO Box 296, Epping, NSW 1710, Australia 12: University of Sydney, Astrophysics Department, School of Physics, A28, Sydney, NSW 2006, Australia 2: Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia 3: University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL 4: Centre for Astrophysics and Supercomputing, Swinburne University, Mail #31, PO Box 218, Hawthorn, VIC 3122, Australia 5: University of Western Sydney Macarthur, Department of Physics, PO Box 555, Campbelltown, NSW 2560, Australia 6: University of Wales, Cardiff, Department of Physics and Astronomy, PO Box 913, Cardiff CF2 3YB 7: Research School of Astronomy and Astrophysics, ANU, Weston Creek PO, Weston, ACT 2611, Australia 8: University of New Mexico, Department of Physics and Astronomy, 800 Yale Blvd. NE, Albuquerque, NM 87131, USA 9: Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
- Free Content
- New Content
- Subscribed Content
- Free Trial Content
Click here for Page Help