The COSI Galactic Science Goals

With a combination of spectral, imaging, and polarization measurement capabilities in the 0.2-5 MeV energy range, COSI will be uniquely equipped to study polarized soft gamma-ray sources in our galaxy. By measuring polarized emission originating from accreting black holes, COSI will probe the acceleration of non-thermal populations of charged particles in the corona and jet regions, advancing our understanding of the formation and geometry of these regions as well as their variability across spectral states. We expect that COSI will allow for previously unattainable observational comparisons between theoretical models of the gamma-ray emitting regions of accreting black holes. Additionally, COSI will investigate other Galactic soft gamma-ray sources, such as pulsars, magnetars, and gamma-ray binaries in the MeV regime.