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Giant Metrewave Radio Telescope limits on cool HI in galaxy groups

D. A. Green·M. S. Clemens·P. Alexander·H. Cullen·B. Nikolic
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Abstract

We present Giant Metrewave Radio Telescope 21-cm HI observations towards a sample of compact radio sources behind galaxy groups, to search for cool HI. The results -- from high dynamic range spectra for 8 lines-of-sight through 7 galaxy groups -- do not show any evidence for absorption by cool HI. At a resolution of 20 km/s, the optical depth upper limits obtained were between 0.0075 and 0.035 (3sigma); these correspond to upper limits of a few times 10**23 m**-2 for the column density of any cool HI along these lines of sight (assuming a spin temperature of 100 K).

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D. A. Green, M. S. Clemens, P. Alexander, H. Cullen, B. Nikolic. 2006-11-27. Giant Metrewave Radio Telescope limits on cool HI in galaxy groups. https://arxiv.org/abs/astro-ph/0611798

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