The newly operational X-ray satellite Suzaku observed the southwestern quadrant of the supernova remnant ( SNR ) RCW 86 in February 2006 to study the nature of the 6.4 keV 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 7.1 keV line that we interpret as the K \beta emission from low-ionization iron .
The Fe-K line features are consistent with a non-equilibrium plasma of Fe-rich ejecta with n _ { e } t \lesssim 10 ^ { 9 } cm ^ { -3 } s and kT _ { e } \sim 5 keV .
This combination of low n _ { e } t and high kT _ { e } suggests collisionless electron heating in an SNR shock .
The Fe K \alpha line shows evidence for intrinsic broadening , with a width of 47 ( 34–59 ) eV ( 99 % error region ) .
The difference of the spatial distributions of the hard continuum above 3 keV and the Fe-K line emission support a synchrotron origin for the hard continuum .