Galactic synchrotron emissivity measurements between 250{\deg} < l < 355{\deg} from the GLEAM survey with the MWA

Synchrotron emission pervades the Galactic plane at low radio frequencies, originating from cosmic ray electrons interacting with the Galactic magnetic field. Using a low-frequency radio telescope, the Murchison Widefield Array (MWA), we measure the free-free absorption of this Galactic synchrotron emission by intervening HII regions along the line of sight. These absorption measurements allow us to calculate the Galactic cosmic-ray electron emissivity behind and in front of 47 detected HII regions in the region $250^\circ < l < 355^\circ$,$|b| < 2^\circ$. We find that all average emissivities between the HII regions and the Galactic edge along the line of sight (${ϵ}_b$) are in the range of 0.24$\sim$0.70$$K$$pc${}^{-1}$ with a mean of 0.40$$K$$pc${}^{-1}$ and a variance of 0.10$$K$$pc${}^{-1}$ at 88$$MHz. Our best model, the Two-circle model, divides the Galactic disk into three regions using two circles centring on the Galactic centre. It shows a high emissivity region near the Galactic centre, a low emissivity region near the Galactic edge, and a medium emissivity region between these two regions, contrary to the trend found by previous studies.