Studying the magnetized ISM with all-sky polarimetric radio maps
  Synchrotron radiation from the interstellar medium (ISM) of our galaxy
dominates the sky brightness at low radio frequencies, and carries information
about relativistic and thermal electron distributions across a range of
astrophysical environments. The polarization of the radiation, as modified by
Faraday rotation effects in the ISM, also contains extensive information about
the magnetic field. Comprehensive all-sky broadband mapping of this radiation,
when combined with high frequency radio data, gamma ray data, cosmic ray (CR)
measurements and sophisticated modeling, can revolutionize our understanding of
the ISM and the processes that influence its evolution.
  Current widefield imagery of the galactic synchrotron emission is
heterogeneous in frequency coverage, sky coverage, angular resolution and
calibration accuracy, limiting utility for ISM studies. A new generation of
all-digital low frequency array technologies is opening a path to matched
resolution, high fidelity polarimetric imaging across a fully sampled swath of
radio frequencies from a few tens to many hundreds of MHz, generating a
transformational dataset for a broad range of scientific applications.
