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XMM observation of M~87 II. Abundance structure of the interstellar and intergalactic medium

Kyoko Matsushita·Alexis Finoguenov·Hans Böhringer
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Abstract

Based on a detailed study of the temperature structure of the intracluster medium in the halo of M~87, abundance profiles of 7 elements, O, Mg, Si, S, Ar, Ca, and Fe are derived. In addition, abundance ratios are derived from the ratios of line strengths, whose temperature dependences are small within the temperature range of the ICM of M~87. The abundances of Si, S, Ar, Ca and Fe show strong decreasing gradients outside 2$'$ and become nearly constant within the radius at $\sim1.5$ solar. The Fe/Si ratio is determined to be 0.9 solar with no radial gradient. In contrast, the O abundance is less than a half of the Si abundance at the center and has a flatter gradient. The Mg abundance is $\sim$1 solar within 2$'$, which is close to stellar abundance within the same radius. The O/Si/Fe pattern of M~87 is located at the simple extension of that of Galactic stars. The observed Mg/O ratio is about 1.25 solar, which is also the same ratio as for Galactic stars. The O/Si/Fe ratio indicates that the SN Ia contribution to Si and Fe becomes important towards the center and SN Ia products have similar abundances of Si and Fe at least around M~87, which may reflect dimmer SN Ia observed in old stellar systems. The S abundance is similar to the Si abundance at the center, but has a steeper gradient. This result suggests that the S/Si ratio of SN II products is much smaller than the solar ratio.

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Kyoko Matsushita, Alexis Finoguenov, Hans Böhringer. 2002-12-03. XMM observation of M~87 II. Abundance structure of the interstellar and intergalactic medium. https://doi.org/10.1051/0004-6361%3A20021791

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