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We present and discuss the results of the Giant Metrewave Radio Telescope H  i 21-cm line mapping for five isolated low-mass (M |$_{\rm bary}$| |$\sim$| (2–8) |$\times 10^7$|  M |$\odot$|⁠) eXtremely Metal Poor dwarfs [12+ |$\log$| (O/H) = 7.13–7.28], selected from the nearby void galaxy sample. All the studied void dwarfs show disturbed morphology in the H  i maps with the angular resolutions of |$\sim 11$| to |$\sim 40\,{\rm arcsec}$|⁠. We examine the H  i morphology and velocity field and the relative orientation of their stellar and gas body spins. We discuss the overall non-equilibrium state of their gas and the possible origin and evolution of the studied void dwarfs. The most straightforward interpretation of the ubiquitous phenomenon of the gas component non-equilibrium state in these and similar void dwarfs is the cold accretion from the void filaments and/or minor mergers. The cold gas accretion in voids could be linked to the presence of small filaments that constitute the substructure of voids. [ABSTRACT FROM AUTHOR]

The Local Void is one of the nearest large voids, located at a distance of 23 Mpc. It lies largely behind the Galactic Bulge and is therefore extremely difficult to observe. We use H  i 21 cm emission observations from the SARAO MeerKAT Galactic Plane Survey (SMGPS) to study the Local Void and its surroundings over the Galactic longitude range 329° < ℓ < 55°, Galactic latitude | b | < 1.5°, and redshift cz < 7500 |$\rm km \, s^{-1}$|⁠. We have detected 291 galaxies to median rms sensitivity of 0.44 mJy per beam per 44 |$\rm km \, s^{-1}$| channel. We find 17 galaxies deep inside the Void, 96 at the border of the Void, while the remaining 178 galaxies are in average density environments. The extent of the Void is ∼58 Mpc. It is severely underdense for the longitude range 350° < ℓ < 35° up to redshift z < 4500 |$\rm km \, s^{-1}$|⁠. The galaxies in the Void tend to have H  i masses that are lower (by approximately 0.25 dex) than their average density counterparts. We find several potential candidates for small groups of galaxies, of which two groups (with 3 members and 5 members) in the Void show signs of filamentary substructure within the Void. [ABSTRACT FROM AUTHOR]

We present the first measurement of the H  i mass function (HIMF) using data from MeerKAT, based on 276 direct detections from the MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) Survey Early Science data covering a period of approximately a billion years (0 ≤ |$z$| ≤ 0.084). This is the first HIMF measured using interferometric data over non-group or cluster field, i.e. a deep blank field. We constrain the parameters of the Schechter function that describes the HIMF with two different methods: |$1/V_{\rm max}$| and modified maximum likelihood (MML). We find a low-mass slope |$\alpha =-1.29^{+0.37}_{-0.26}$| , 'knee' mass |$\log _{10}(M_{*}/{\rm {\rm M}_{\odot }}) = 10.07^{+0.24}_{-0.24}$| and normalization |$\log _{10}(\phi _{*}/\rm Mpc^{-3})=-2.34^{+0.32}_{-0.36}$| (H 0 = 67.4 km s−1 Mpc−1) for |$1/V_{\rm max}$| , and |$\alpha =-1.44^{+0.13}_{-0.10}$| , 'knee' mass |$\log _{10}(M_{*}/{\rm {\rm M}_{\odot }}) = 10.22^{+0.10}_{-0.13}$| and normalization |$\log _{10}(\phi _{*}/\rm Mpc^{-3})=-2.52^{+0.19}_{-0.14}$| for MML. When using |$1/V_{\rm max}$| we find both the low-mass slope and 'knee' mass to be consistent within 1σ with previous studies based on single-dish surveys. The cosmological mass density of H  i is found to be slightly larger than previously reported: |$\Omega _{\rm H\,{\small I}}=5.46^{+0.94}_{-0.99} \times 10^{-4}\,h^{-1}_{67.4}$| from |$1/V_{\rm max}$| and |$\Omega _{\rm H\,{\small I}}=6.31^{+0.31}_{-0.31} \times 10^{-4}\,h^{-1}_{67.4}$| from MML but consistent within the uncertainties. We find no evidence for evolution of the HIMF over the last billion years. [ABSTRACT FROM AUTHOR]

Here we report the discovery with the Giant Metrewave Radio Telescope of an extremely large (∼115 kpc in diameter) H  i ring, located around a massive quenched galaxy, AGC 203001, but off-centred with respect to it. This ring does not have any bright extended optical counterpart unlike several other known ring galaxies. Our deep g -, r- , and i -band optical imaging of the H  i ring, using the MegaCam instrument on the Canada–France–Hawaii Telescope, shows however several regions with faint optical emission at a surface brightness level of ∼28 mag arcsec−2. Such an extended H  i structure is very rare with only one other case known so far – the Leo ring. Conventionally, off-centred rings have been explained by a collision with an 'intruder' galaxy leading to expanding density waves of gas and stars in the form of a ring. However, in such a scenario the impact also leads to large amounts of star formation in the ring that is not observed in the ring presented in this paper. We discuss possible scenarios for the formation of such H  i -dominated rings. [ABSTRACT FROM AUTHOR]