Cosmic-ray leptons, magnetic fields and interstellar synchrotron
  emission
  Interstellar synchrotron emission depends on Galactic magnetic fields and on
cosmic-ray leptons. Observations of radio emission are an important tool for
studying cosmic-ray propagation models and interstellar electron spectrum and
distribution in the Galaxy. We present the latest developments in our modeling
of Galactic synchrotron emission with the GALPROP code, including polarization,
absorption, and free-free emission. Using surveys over a wide range of radio
frequencies and polarization measurements, we derive constraints on the
low-energy interstellar cosmic-ray electron spectrum, magnetic fields and
cosmic-ray propagation models. This work is of interest for studies of
interstellar gamma-ray emission with Fermi-LAT, and synchrotron for the Planck
mission.
