Publications (2)0 Total impact
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ABSTRACT: We investigate the neutral hydrogen (HI) content of sixteen groups for which we have multi-wavelength data including X-ray observations. Wide-field imaging of the groups was obtained with the 20-cm multibeam system on the 64-m Parkes telescope. We have detected ten previously uncatalogued HI sources, one of which has no visible optical counterpart. We examine the HI properties of the groups, compared to their X-ray characteristics, finding that those groups with a higher X-ray temperature and luminosity contain less HI per galaxy. The HI content of a group depends on its morphological make-up, with those groups dominated by early-type galaxies containing the least total HI. We determined the expected HI for the spiral galaxies in the groups, and found that a number of the galaxies were HI deficient. The HI deficient spirals were found both in groups with and without a hot intra-group medium. The HI deficient galaxies were not necessarily found at the centre of the groups, however, we did find that two thirds of HI deficient galaxies were found within about 1 Mpc from the group centre, indicating that the group environment is affecting the gas-loss from these galaxies. We determined the HI mass function for a composite sample of 15 groups, and found that it is significantly flatter than the field HI mass function. We also find a lack of high HI-mass galaxies in groups. One possible cause of this effect is the tidal stripping of HI gas from spiral galaxies as they are pre-processed in groups. Comment: accepted for publication in MNRAS, 26 pages, 13 Figures, 2 Appendices
09/2009;
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ABSTRACT: We report on neutral hydrogen observations of a ~ 5.5 x 5.5 degree field
around the NGC 1566 galaxy group with the multibeam narrow-band system on the
64-m Parkes telescope. We detected thirteen HI sources in the field, including
two galaxies not previously known to be members of the group, bringing the
total number of confirmed galaxies in this group to 26. Each of the HI galaxies
can be associated with an optically catalogued galaxy. No 'intergalactic HI
clouds' were found to an HI mass limit of ~ 3.5 x 10^8 Msun. We have estimated
the expected HI content of the late-type galaxies in this group and find the
total detected HI is consistent with our expectations. However, while no global
HI deficiency is inferred for this group, two galaxies exhibit individual HI
deficiencies. Further observations are needed to determine the gas removal
mechanisms in these galaxies.
09/2004;
