MIGHTEE-HI: Discovery of an HI-rich galaxy group at z = 0.044 with MeerKAT

Abstract

We present the serendipitous discovery of a galaxy group in the XMM-LSS field with MIGHTEE Early Science observations. Twenty galaxies are detected in HI in this $z\sim 0.044$ group, with a $3\sigma$ column density sensitivity of $N_{\mathrm{HI}}=1.6\times 10^{20}{\mathrm{cm}}^{-2}$. This group has not been previously identified, despite residing in a well-studied extragalactic legacy field. We present spatially-resolved HI total intensity and velocity maps for each of the objects, which reveal environmental influence through disturbed morphologies. The group has a dynamical mass of ${\log }_{10}(M_{\mathrm{dyn}}/{\mathrm{M}}_{\odot })=12.32$, and is unusually gas-rich, with an HI-to-stellar mass ratio of ${\log }_{10}(f_{\mathrm{HI}}^{\ast })=-0.2$, which is 0.7 dex greater than expected. The group's high HI content, spatial, velocity, and identified galaxy type distributions strongly suggest that it is in the early stages of its assembly. The discovery of this galaxy group is an example of the importance of mapping spatially-resolved HI in a wide range of environments, including galaxy groups. This scientific goal has been dramatically enhanced by the high sensitivity, large field-of-view, and wide instantaneous bandwidth of the MeerKAT telescope.

13 pages, 6 figures, accepted for publication in MNRAS

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Cited by in corpus (8)

• MIGHTEE-HI: The baryonic Tully-Fisher relation over the last billion years
• MIGHTEE-HI: the HI Size-Mass relation over the last billion years
• MUSE-ALMA Haloes VII: Survey Science Goals & Design, Data Processing and Final Catalogues
• MIGHTEE-HI: deep spectral line observations of the COSMOS field
• Emission-line Stacking of 21cm Intensity Maps with MeerKLASS: Inference Pipeline and Application to the L-band Deep-field Data
• A serendipitous discovery of HI-rich galaxy groups with MeerKAT
• MIGHTEE-\HI: Possible interactions with the galaxy NGC~895
• A MeerKAT study of a neutral hydrogen rich grouping of galaxies with megaparsec-scale filamentary-like structure