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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 ($epsilon_b$) 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.
We present the Forgotten Quadrant Survey (FQS), an ESO large project that used the 12m antenna of the Arizona Radio Observatory to map the Galactic Plane in the range 220deg$<l<$240deg and -2.5deg$<b<$0deg, both in $^{12}$CO(1-0) and $^{13}$CO(1-0),
The Multipurpose InfraRed Imaging System (MIRIS) performed the MIRIS Pa{alpha} Galactic Plane Survey (MIPAPS), which covers the entire Galactic plane within the latitude range of -3{deg} < b < +3{deg} at Pa{alpha} (1.87 um). We present the first resu
Surveys of the Milky Way at various wavelengths have changed our view of star formation in our Galaxy considerably in recent years. In this paper we give an overview of the GLOSTAR survey, a new survey covering large parts (145 square degrees) of the
(Abridged) We present the first public release of high-quality data products (DR1) from Hi-GAL, the {em Herschel} infrared Galactic Plane Survey. Hi-GAL is the keystone of a suite of continuum Galactic Plane surveys from the near-IR to the radio, and
We derive the synchrotron distribution in the Milky Way disk from HII region absorption observations over -40{deg} < l < 40{deg} at six frequencies of 76.2, 83.8, 91.5, 99.2, 106.9, and 114.6 MHz with the GaLactic and Extragalactic All-sky Murchison