NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-05-24 T08:56:54 PDT
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For refcode 2003MNRAS.346..787M:
Retrieve 173 NED objects in this reference.
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NED Abstract

Copyright by Royal Astronomical Society. 2003MNRAS.346..787M HIDEEP - an extragalactic blind survey for very low column-density neutral hydrogen Minchin, R. F.; Disney, M. J.; Boyce, P. J.; de Blok, W. J. G.; Parker, Q. A.; Banks, G. D.; Freeman, K. C.; Garcia, D. A.; Gibson, B. K.; Grossi, M.; Haynes, R. F.; Knezek, P. M.; Lang, R. H.; Malin, D. F.; Price, R. M.; Stewart, I. M.; Wright, A. E. Abstract. We have carried out an extremely long integration time (9000 s beam^-1^) 21-cm blind survey of 60 deg^2^ in Centaurus using the Parkes multibeam system. We find that the noise continues to fall as square root t_obs_ throughout, enabling us to reach an HI column-density limit of 4.2 x 10^18^ cm^-2^ for galaxies with a velocity width of 200 km s^-1^ in the central 32 deg^2^ region, making this the deepest survey to date in terms of column density sensitivity. The HI data are complemented by very deep optical observations from digital stacking of multi-exposure UK Schmidt Telescope R-band films, which reach an isophotal level of 26.5 R mag arcsec^-2^ (~=27.5 B mag arcsec^-2^). 173 HI sources have been found, 96 of which have been uniquely identified with optical counterparts in the overlap area. There is not a single source without an optical counterpart. Although we have not measured the column densities directly, we have inferred them from the optical sizes of their counterparts. All appear to have a column density of N_HI_= 10^20.65+/-0.38^. This is at least an order of magnitude above our sensitivity limit, with a scatter only marginally larger than the errors on N_HI_. This needs explaining. If confirmed it means that HI surveys will only find low surface brightness (LSB) galaxies with high M_HI_/L_B_. Gas-rich LSB galaxies with lower HI mass to light ratios do not exist. The paucity of low column-density galaxies also implies that no significant population will be missed by the all-sky HI surveys being carried out at Parkes and Jodrell Bank.
Retrieve 173 NED objects in this reference.
Please click here for ADS abstract

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