ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O B-CelestialObject I-CelestialObject B-Citation I-Citation I-Citation I-Citation O O O O O O O O O B-CelestialObject I-CelestialObject B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O B-Wavelength O O O O O O O O O O O O O B-Telescope B-Wavelength O O O O O O O O B-Telescope O O O O O O O O O O O O O B-Survey O O O O B-Wavelength O O O O O O O O B-CelestialObject I-CelestialObject B-CelestialObject I-CelestialObject O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O B-Wavelength O O O B-Survey O O O O O O O O O B-Survey O B-Survey O O O O O O O O O O O O O O O O O O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O B-Survey I-Survey O O O O O O O O O B-Wavelength O O O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O
tokens: feedback on the cold neutral gas. For some sources we could only search for intervening H i absorption (e.g. gas intervening DLAs along the line of sight), which is an alternate cause for obscuration of the background radio quasar. Lastly, for some sources observed we had no prior redshift information. We report three H i absorption detections in our sample, one towards PKS 1829−718 that was previously unknown, another towards PKS 1740−517 (Allison et al. 2015 ), and the third a re-detection of one towards PKS 0500+019 (Carilli et al. 1998 ). All three detections are made towards sources selected by optical faintness, and we see no H i absorption towards sources selected by their WISE mid-infrared colours. However, the lack of detections in the WISE selected sub-sample is not yet statistically significant, and further analysis during the full FLASH project is required. Through optical spectroscopic follow-up and information within the literature for PKS 1829−718, PKS 1740−517, and PKS 0500+019, we find that the detected H i absorption is associated with the host galaxy of the AGN in each case. These three AGN are obscured by material in the host galaxy, e.g. a dusty torus formed following a galaxy merger event, or perhaps in a larger disc on the scale of ∼100 pc. We do not detect any H i absorption towards our higher redshift targets ( z > 1). This is not necessarily unexpected given the predicted number of DLAs along the line of sight for our redshift range of 0.4 z 1. One factor which negatively contributed to this include the occasional correlator block error resulting in corrupted segments of the spectrum. Another is that some targets had limited integration time resulting in higher optical depth limits, and corresponding higher H i column density upper limits (Table 3 ). This lowered our sensitivity to detecting H i gas in absorption. All detections are made towards GPS sources, and we find a 33 per cent H i associated absorption detection rate towards the GPS sources in our sample. These GPS sources are compact in linear extent and believed to be young or re-triggered in their AGN activity. We also find shallow and asymmetric H i absorption features in our survey, as seen in Carilli et al. ( 1998 ) and Ishwara-Chandra et al. ( 2003 ) towards red quasars, and low redshift studies towards young radio AGN. The full FLASH project, alongside other future all-sky H i absorption surveys (MALS and SHARP), will better increase our H i statistics. This in turn will improve our understanding of the impact of the radio AGN on its cold gas, and its evolution with redshift, during this crucial transitional stage in galaxy evolution. Intervening H i absorption studies alongside the other ASKAP survey science projects will increase our statistics of the obscured radio AGN population missed in optically selected samples, and understanding of the distribution of cold neutral gas with redshift for such sources. SUPPORTING INFORMATION Figure 9 . Averaged