region is discussed and analyzed in §3.4.

Temperature and Metal Abundances
--------------------------------

Distributions of temperature and metal abundances are plotted against radius (kpc) in Figures 4 and 5, respectively. Systematic errors due to the GXE, CXB, and NXB are also shown. The systematic errors due to the GXE are estimated by varying the normalizations of the APEC model for the MWH and LHB within their error ranges, which are comparable to the X-ray count fluctuation (15%) of the ROSAT All-sky X-ray background survey (band 4)[^1] for the NGC 4636 region. The systematic errors due to the CXB and NXB are at most 5% (Tawara et al. 2008), respectively, and they are dominant in the hard X-ray band. Therefore, the systematic errors on the temperature and metal abundances are mostly caused by the GXE uncertainty. A 15% uncertainty in the estimate of the XIS optical blocking filter thickness introduces systematic errors comparable to those from the GXE. The temperature in the central region is 0.64 keV, rising to 0.7–0.8 keV. This profile is consistent with that from ASCA (Matsushita et al. 1997), XMM-Newton (Xu et al. 2002) and Chandra (Ohto et al. 2003) and the temperature distribution is barely affected by 