Mon. Not. R. Astron. Soc., 337, 641-656 (2002/December-1)
The large-scale distribution of neutral hydrogen in the Fornax region.
WAUGH M., DRINKWATER M.J., WEBSTER R.L., STAVELEY-SMITH L., KILBORN V.A., BARNES D.G., BHATHAL R., DE BLOK W.J.G., BOYCE P.J., DISNEY M.J., EKERS R.D., FREEMAN K.C., GIBSON B.K., HENNING P.A., JERJEN H., KNEZEK P.M., KORIBALSKI B., MARQUARDING M., MINCHIN R.F., PRICE R.M., PUTMAN M.E., RYDER S.D., SADLER E.M., STOOTMAN F. and ZWAAN M.A.
Abstract (from CDS):
Using data from the Hi Parkes All Sky Survey (HIPASS), we have searched for neutral hydrogen in galaxies in a region ∼25x25 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 3σ lower flux limit of ∼40 mJy, 110 galaxies with Hi 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 Hi 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 Hi detections. Of 62 Hi 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 Hi-rich galaxies in the centre of the cluster. However, relative to the field, there is a 3(±1)-fold excess of Hi-rich galaxies in the outer parts of the cluster where galaxies may be infalling towards the cluster for the first time.
surveys - galaxies: clusters: individual: Fornax - galaxies: evolution - large-scale structure of Universe - radio lines: galaxies
VizieR on-line data:
<Available at CDS (J/MNRAS/337/641): table1.dat>
Table 1: [WDW2002] HIPASS JHHMM+DDa N=110.
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