Presentation #302.02 in the session Transients and Time-domain Astronomy.
Magnetic field plays an essential role in the plasma dynamics and particle acceleration in high-energy astrophysical systems. Polarization offers a direct view of the magnetic field morphology and evolution in these systems. With the recent launch of IXPE and the recently selected COSI, X-ray and MeV polarimetry can offer unique insights into the origin of extragalactic cosmic rays and neutrinos, as well as extreme particle acceleration processes therein. In this poster, I will present theoretical predictions for X-ray and MeV polarization for blazars, gamma-ray bursts, and pulsar wind nebulae.