Distribution of Si, Fe, and Ni in the Intracluster Medium of the Coma
  Cluster
  We studied the distributions of Si, Fe, and Ni in the intracluster medium
(ICM) of the Coma cluster, one of the largest clusters in the nearby universe,
using XMM-Newton data up to 0.5 r180 and Suzaku data of the central region up
to 0.16 r180. Using the flux ratios of Ly alpha of H-like Si and 7.8 keV blend
to K alpha of He-like Fe, the abundance ratios of Si to Fe and Ni to Fe of the
ICM were derived using APEC model v2.0.1. The Si/Fe ratio in the ICM of the
Coma cluster shows no radial gradient. The emission weighted averages of the
Si/Fe ratio in the ICM within 0.0--0.2 r180, 0.2--0.5 r180, and 0.0--0.5 r180
are 0.97 +- 0.11, 1.05 +- 0.36 and 0.99 +- 0.13, respectively, in solar units
using the solar abundance of Lodders (2003). These values are close to those of
smaller clusters and groups of galaxies. Using the Suzaku data of the central
region, the derived Ni/Fe ratio of the ICM is 0.6--1.5 in solar units,
according to the same solar abundance table. The systematic difference in the
derived abundance ratios by different plasma codes are about 10%. Therefore,
for the ICM in the Coma cluster, the abundance pattern of Si, Fe, and Ni is
consistent with the same mixture of the yields of SN II and SN Ia in our
Galaxy. Within 0.5 r180}, the cumulative iron-mass-to-light ratio increases
with radius, and its radial profile is similar to those of relaxed smaller
clusters with cD galaxies at their center. Considering the observed Si/Fe
ratio, the cumulative metal-mass-to-light ratios at 0.5 r180 are compared with
theoretical expectations.
