Suzaku and XMM-Newton Observations of the Fornax Cluster: Temperature and Metallicity Distribution

Abstract

Abstract Suzaku observed a central region and five offset regions within 0.2 $\ r_{180}$ in the Fornax cluster, a nearby poor cluster, and XMM-Newton mapped the cluster with 15 pointings out to 0.3 $\ r_{180}$ . The distributions of O, Mg, Si, S, and Fe in the intracluster medium (ICM) were studied with Suzaku, and those of Fe and temperature were studied with XMM. The temperature of the ICM gradually decreases with the radius from 1.3 keV at 0.04 $\ r_{180}$ to 1 keV at 0.2–0.3 $\ r_{180}$ . If the new solar abundances of Lodders et al. (2003), ApJ, 591, 1220) and a single-temperature plasma model are adopted, O, Mg, Si, S, and Fe show similar abundances: 0.4–0.6 solar within 0.02–0.2 $\ r_{180}$ . This Fe abundance is similar to those at 0.1–0.2 $\ r_{180}$ in rich clusters and other groups of galaxies. At 0.2–0.3 $\ r_{180}$ , the Fe abundance becomes 0.2–0.3 solar. A two-temperature plasma model yields ICM abundances that are higher by a factor of 1.2–1.5, but give similar abundance ratios among O, Mg, Si, S, and Fe. The northern region has a lower ICM temperature and higher brightness and Fe abundance, whereas the southern region has a higher ICM temperature and lower brightness and Fe abundance. These results indicate that the cD galaxy may have traveled from the north because of recent dynamical evolution. The cumulative oxygen- and iron-mass-to-light ratios (OMLR and IMLR) within 0.3 $\ r_{180}$ are an order of magnitude lower than those of rich clusters and some relaxed groups of galaxies. Past dynamical evolution might have hindered the strong concentration of hot gas in the Fornax cluster's central region. Scatter in the IMLR and similarity in the element abundances in the ICM of groups and clusters of galaxies indicate early metal synthesis.