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[99.06D] Electron-Ion Equilibration at Supernova Remnant Shock Fronts

C.E. Rakowski (Rutgers Univ.)

The degree of electron and proton heating at collisionless shocks is an open question in plasma physics. Any initial post-shock electron to proton temperature ratio from minimal heating of T_e/T_p = m_e/m_p up to full equilibration of T_e/T_p = 1 is theoretically possible. Assuming either full or minimal equilibration when inferring the shock speed from a single temperature measurement leads to a large range of possible total shock energies. For my thesis I investigated this problem by examining the ratio of electron to proton temperatures in the outer blast wave of supernova remnant DEM L71 in the Large Magellanic Cloud. The proton temperatures were measured from broad H\alpha widths observed using the Rutgers Fabry-Perot imaging spectrograph, while the electron temperatures were measured from Chandra X-ray data. With the use of new post-shock non-equilibrium ionization models for the electron temperature evolution we find evidence for an intermediate degree of temperature equilibration for shock speeds of 400-1000~km~s^-1. Our results are consistent with the trend found in other remnants by Ghavamian et~al.~(2001) of decreasing initial electron heating with increasing shock velocity. Further explorations of the degree of electron-proton equilibration will be presented as time permits. C.E. Rakowski has been supported by a NASA Graduate Student Researchers Program fellowship.

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.