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arXiv · 2212.06680

HI absorption associated with Norma's brightest cluster galaxy

Manasvee Saraf·O. Ivy Wong·Luca Cortese·Bärbel S. Koribalski
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Abstract

ESO 137-G006 is the brightest cluster galaxy (BCG) of the cool-core and dynamically young Norma cluster. We discover an atomic hydrogen (HI) absorption line associated with this BCG using the Australia Telescope Compact Array. We estimate a gas column density of $ \approx (1.3 \pm 0.2) \times 10^{20}\,T_{\rm{spin}}$ atoms cm$^{-2}$ with spin temperature, $T_{\rm{spin}} \leq 194$ K, consistent with the HI properties of other early-type galaxies and cool-core cluster BCGs. The relationship between the presence of cold gas and a cluster cooling flow is unclear. Our results support the scenario that ESO 137-G006 may be a recent arrival to the cluster centre and not the original BCG. This scenario is consistent with the observed spatial alignment of the BCG's wide-angle tail radio lobes with Norma's X-ray sub-cluster and the significant line-of-sight velocity offset between the mean velocity of Norma and that of the BCG.

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Manasvee Saraf, O. Ivy Wong, Luca Cortese, Bärbel S. Koribalski. 2022-12-13. HI absorption associated with Norma's brightest cluster galaxy. https://doi.org/10.1093/mnras%2Fstac3695

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