MIGHTEE-HI: discovery of an H i-rich galaxy group at z = 0.044 with MeerKAT. Issue 2 (22nd July 2021)

• Record Type: Journal Article
• Authors: Ranchod, Shilpa; Deane, Roger P; Ponomareva, Anastasia A; Blecher, Tariq; Frank, Bradley S; Jarvis, Matt J; Maddox, Natasha; Mulaudzi, Wanga; Glowacki, Marcin; Hess, Kelley M; Tudorache, Madalina; Verdes-Montenegro, Lourdes; Adams, Nathan J; Bowler, Rebecca A A; Collier, Jordan D; Taylor, Russ
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 506:Issue 2(2021)
• Page Start: 2753
• Page End: 2765
• Publication Date: 2021-07-22
• Subjects: instrumentation: interferometer -- galaxies: evolution -- galaxies: groups: individual -- radio lines: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab1817
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present the serendipitous discovery of a galaxy group in the XMM -LSS field with MIGHTEE Early Science observations. 20 galaxies are detected in H i in this z ∼ 0.044 group, with a 3σ column density sensitivity of $N_{\rm H\, \small {I}} = 1.6\times 10^{20}\, \mathrm{cm}^{-2}$ . This group has not been previously identified, despite residing in a well-studied extragalactic legacy field. We present spatially resolved H i total intensity and velocity maps for each of the objects which reveal environmental influence through disturbed morphologies. The group has a dynamical mass of $\log_{10} (M_{\rm dyn}/\mathrm{M}_\odot) = 12.32$, and is unusually gas-rich, with an H i -to-stellar mass ratio of $\log _{10}(f_{\rm H\, \small {I}}^\mathrm{*}) = -0.2$, which is 0.7 dex greater than expected. The group's high H i 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 H i 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.