The abundance pattern of O, Mg, Si, and Fe in the intracluster medium of the Centaurus cluster observed with XMM-Newton

¹ Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjyuku-ku, Tokyo 162-8601, Japan e-mail: matusita@rs.kagu.tus.ac.jp
² Max-Planck-Institut für Extraterrestrial Physik, 85748 Garching, Germany
³ Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan,
⁴ Joint Center for Astrophysics, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA

Received: 15 April 2003
Accepted: 9 October 2006

Abstract

The abundances of O, Mg, Si, and Fe in the intracluster medium of the Centaurus cluster are derived. The Fe abundance has a negative radial gradient. In solar units, the Si abundance is close to the Fe abundance, while the O and Mg abundances are much lower. The high Fe/O and Si/O ratios indicate that the metal supply from supernovae Ia is important and that supernovae Ia synthesize Si as does Fe. Within 2', the O and Mg abundances are consistent with the stellar metallicity of the cD galaxy derived from the Mg₂ index. This result indicates that the central gas is dominated by the gas from the cD galaxy. The observed abundance pattern of the Centaurus cluster resembles those observed in the center of other clusters and groups of galaxies. However, the central Fe abundance and the Si/Fe ratio are 40% higher and 30% lower than those of M 87, respectively. Since the accumulation timescale of the supernovae Ia is greater in the Centaurus cluster, these differences imply a time dependence of nucleosynthesis by the supernovae Ia.