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S. P. Reynolds (NC State U.)
Radio polarization observations of shell supernova remnants show that magnetic fields are usually partly disordered, highly disordered in the case of young remnants. Such observations also give an idea of the dominant magnetic-field orientation of the ordered component (radial in young remnants; tangential or confused in older ones). The observations are typically hampered by Faraday rotation and depolarization effects. Until now, it has not been possible to perform X-ray polarization observations of shell supernova remnants, but several proposed X-ray polarimeters would be able to detect such polarization. These observations could confirm the presence of synchrotron X-rays in a few remnants, and could provide direct information about magnetic-field order and geometry totally free from Faraday rotation and depolarization problems. I present simulations of radio and X-ray synchrotron emission from shell supernova remnants illustrating the potential for such X-ray observations. I assume Sedov dynamics and shock acceleration of electrons with a power-law distribution, exponentially cut off due to radiative losses, escape, or finite acceleration time. The distribution evolves behind the shock due to adiabatic and radiative losses. The immediate post-shock magnetic field is either related to a perfectly ordered upstream field by simple compression, or is randomized in orientation, and evolves subsequently by flux freezing. The thinner X-ray emitting layer means that spatial inhomogeneities cause less dilution of the polarized signal, but the poorer angular resolution of proposed X-ray polarimeters compared to typical radio interferometric observations means that interpretation of observations will still have some model dependence.
This work was supported by NASA's Astrophysics Theory Program.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.