H i galaxy signatures in the SARAO MeerKAT galactic plane survey – II. The Local Void and its substructure.

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]