In this Letter we use the unprecedented spatial resolution of the Chandra X-Ray Observatory to carry out , for the first time , a measurement of the post-shock electron temperature and proper motion of a young SNR , specifically to address questions about the post-shock partition of energy among electrons , ions , and cosmic rays .
The expansion rate , 0.100 \% \pm 0.025 \% yr ^ { -1 } , and inferred age , \sim 1000 yr , of E0102.2 - 7219 , from a comparison of X-ray observations spanning 20 years , are fully consistent with previous estimates based on studies of high velocity oxygen-rich optical filaments in the remnant .
With a radius of 6.4 pc for the blast wave estimated from the Chandra image , our expansion rate implies a blast wave velocity of \sim 6000 km s ^ { -1 } and a range of electron temperatures 2.5 - 45 keV , dependent on the degree of collisionless electron heating .
Analysis of the Chandra ACIS spectrum of the immediate post-shock region reveals a thermal plasma with abundances and column density typical of the Small Magellanic Cloud and an electron temperature of 0.4–1 keV .
The measured electron temperature is significantly lower than the plausible range above , which can only be reconciled if we assume that a significant fraction of the shock energy , rather than contributing to the heating of the post-shock electrons and ions , has gone into generating cosmic rays .