H I absorption associated with Norma's brightest cluster galaxy

ESO 137-G006 is the brightest cluster galaxy (BCG) of the cool-core and dynamically young Norma cluster. We discover anatomic hydrogen (H I) absorption line associated with this BCG using the Australia Telescope Compact Array. We estimate a gascolumn density of ≈ (1.3 ± 0.2) × 1020 Tspin atoms cm−2 with spin temperature, Tspin ≤ 194 K, consistent with the H I propertiesof other early-type galaxies and cool-core cluster BCGs. The relationship between the presence of cold gas and a cluster coolingflow is unclear. Our resultssupport the scenario that ESO 137-G006 may be a recent arrival to the cluster centre and not the originalBCG. This scenario is consistent with the observed spatial alignment of the BCG’s wide-angle tail radio lobes with Norma’sX-ray sub-cluster and the significant line-of-sight velocity offset between the mean velocity of Norma and that of the BCG.