A search for 21 cm H I absorption in AT20G compact radio galaxies

We present results from a search for 21 cm associated H I absorption in a sample of 29 radio sources selected from the Australia Telescope 20 GHz survey. Observations were conducted using the Australia Telescope Compact Array Broadband Backend, with which we can simultaneously look for 21 cm absorption in a redshift range of 0.04 . z . 0.08, with a velocity resolution of 7 km s 1 . In preparation for future largescale H I absorption surveys we test a spectral-line finding method ba sed on Bayesian inference. We use this to assign significance to our detectio ns and to determine the best-fitting number of spectral-line components. We find tha t the automated spectralline search is limited by residuals in the continuum, both fr om the band-pass calibration �

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