Citation for published item:g tinell D f r r nd intongeD em¡ elie nd t nowie kiD teven nd gorteseD vu nd h v¡ eD omeel nd vemoni sD tenn t nd gooperD endrew nd himinovi hD h vid nd rummelsD g meron f nd p elloD ilvi nd qer¡ e D u tink nd uil ornD irgini nd ngD ting @PHIVA 9xqe X tot l old g s s ling rel tions nd mole ul rEtoE tomi g s r tios of g l xies in the lo l niverseF9D wonthly noti es of the oy l estronomi l o ietyFD RUT @IAF ppF VUSEVWSF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

We present an analysis of the properties of neutral hydrogen (H i) in 248 nearby (0.02 < z < 0.25) radio galaxies with S 1.4 GHz > 30 mJy and for which optical spectroscopy is available. The observations were carried out with the Westerbork Synthesis Radio Telescope as the last large project before the upgrade of the telescope with phased array feed receivers (Apertif). The sample covers almost four orders of magnitude in radio power from log P 1.4 GHz = 22.5 W Hz −1 and 26.2 W Hz −1 . We detect H i in absorption in 27% ± 5.5% of the objects. The detections are found over the full range of radio power. However, the distribution and kinematics of the absorbing H i gas appear to depend on radio power, the properties of the radio continuum emission, and the dust content of the sources. Among the sources where H i is detected, gas with kinematics deviating from regular rotation is more likely found as the radio power increases. In the great majority of these cases, the H i profile is asymmetric with a significant blue-shifted component. This is particularly common for sources with log P 1.4 GHz > 24 W Hz −1 , where the radio emission is small, possibly because these radio sources are young. The same is found for sources that are bright in the mid-infrared, i.e. sources rich in heated dust. In these sources, the H i is outflowing likely under the effect of the interaction with the radio emission. Conversely, in dust-poor galaxies, and in sources with extended radio emission, at all radio powers we only detect H i distributed in a rotating disk. Stacking experiments show that in sources for which we do not detect H i in absorption directly, the H i has a column density that is lower than 3.5 × 10 17 (T spin /c f ) cm −2 . We use our results to predict the number and type of H i absorption lines that will be detected by the upcoming surveys of the Square Kilometre Array precursors and pathfinders (Apertif, MeerKAT, and ASKAP).

We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S 1.4 GHz > 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The H I absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected H I lines lies in the range 32 km s −1 < FWHM < 570 km s −1 , whereas the full width at 20% of the peak absorption (FW20) lies in the range 63 km s −1 < FW20 < 825 km s −1 . The width and asymmetry of the profiles allows us to identify three groups: narrow lines (FWHM < 100 km s −1 ), intermediate widths (100 km s −1 < FWHM < 200 km s −1 ), and broad profiles (FWHM > 200 km s −1 ). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of H I. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating H I disks or gas clouds. More H I disks can be present among galaxies with lines of intermediate widths; however, the H I in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled H I gas. In particular, besides three of the broadest (up to FW20 = 825 km s −1 ) detections, which are associated with gas-rich mergers, we find three new cases of profiles with blueshifted broad wings (with FW20 > ∼ 500 km s −1 ) in high radio power AGN. These detections are good candidates for being HI outflows. Together with the known cases of outflows already included in the sample (3C 293 and 3C 305), the detection rate of H I outflows is 5% in the total radio AGN sample. Because of the effects of spin temperature and covering factor of the outflowing gas, this fraction could represent a lower limit. However, if the relatively low detection rate is confirmed by more detailed observations, it would suggest that, if outflows are a characteristic phenomenon of all radio AGN, they would have a short depletion timescale compared to the lifetime of the radio source. This would be consistent with results found for some of the outflows traced by molecular gas. Using stacking techniques, in our previous paper we showed that compact radio sources have higher τ, FWHM, and column density than extended sources. ...

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 large‐scale H i absorption surveys we test a spectral‐line finding method based on Bayesian inference. We use this to assign significance to our detections and to determine the best‐fitting number of spectral‐line components. We find that the automated spectral‐line search is limited by residuals in the continuum, both from the band‐pass calibration and spectral‐ripple subtraction, at spectral‐line widths of ΔvFWHM≳ 103 km s−1. Using this technique we detect two new absorbers and a third, previously known, yielding a 10 per cent detection rate. Of the detections, the spectral‐line profiles are consistent with the theory that we are seeing different orientations of the absorbing gas, in both the host galaxy and circumnuclear disc, with respect to our line of sight to the source. In order to spatially resolve the spectral‐line components in the two new detections, and so verify this conclusion, we require further high‐resolution 21 cm observations (∼0.01 arcsec) using very long baseline interferometry.