H I galaxy signatures in the SARAO MeerKAT galactic plane survey - II. The Local Void and its substructure
Abstract
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.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2024
- DOI:
- 10.1093/mnras/stad3823
- arXiv:
- arXiv:2312.05237
- Bibcode:
- 2024MNRAS.528..542K
- Keywords:
-
- galaxies: evolution;
- galaxies: ISM;
- catalogues;
- surveys;
- large-scale structure of Universe;
- radio lines: galaxies;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted for publication in MNRAS