2007PASJ...59S.171U

The newly operational X-ray satellite Suzaku observed the southwestern quadrant of the supernova remnant RCW 86 in 2006 February to study the nature of the 6.4keV emission line first detected with the Advanced Satellite for Cosmology and Astronomy (ASCA). The new data confirm the existence of the line, localizing it for the first time; most of the line emission is adjacent and interior to the forward shock, and not at the locus of the continuum hard emission. We also report the first detection of a 7.1keV line, which we interpret as Kb emission from low-ionization iron. The Fe K line features are consistent with a non-equilibrium plasma of Fe-rich ejecta with n_et \lesssim 10⁹/cm3 s and kT_e ∼ 5 keV. This combination of low n_et and high kT_e suggests collisionless electron heating in an SNR shock. The Fe Kα line shows evidence for intrinsic broadening, with a width of 47 (34-59) eV (99% error region). The difference in the spatial distributions of the hard continuum above 3keV and the Fe K line emission supports a synchrotron origin for the hard continuum.