The Extended Radio Source In The Center Of M31
R. M. Hjellming and L. Smarr, Astrophysical Journal Letters, 257, L13-L18 (1982).
Abstract
Radio observations of the central Io X Io region of the Andromeda Nebula (M31), made with the 1 km configuration of the NRAO VLA, show that at 1465 MHz the central radio source is nearly spherical and 2 kpc (10′) in diameter, with a brightness distribution roughly proportional to exp(—R/l’l), where R is the angular distance from the radio maximum located 20″ from the nucleus at a position angle of 70°. The broad structure of this object may be due to a bulge population of many weak supernova remnants or to a cosmic-ray electron-dominated galactic wind.