The radio spectrum of Sgr A*
  We discuss the radio spectrum of Sgr A* \index{Sgr A*, radio spectrum} in the frequency range between $\approx 1\,{\rm GHz}$ and $\approx 1\,000\,{\rm GHz}$, show that it can be explained by optically thin synchrotron radiation \index{Sgr A*, synchrotron radiation, optically thin} of relativistic electrons, and point toward a possible correlation between the spectrum of Sgr A* and larger-scale ($\la 50\,{\rm pc}$) radio emission from the Galactic Center \index{Galactic Center} region. 
Wolfgang J. Duschl and Harald Lesch