Roles of SN IA and SN II in ICM Enrichment
Abstract
Based on ASCA observations Mushotzky et al. (1996, ApJ 466, 686) have recently derived the relative abundance ratios of alpha -elements to iron, [alpha /Fe] =~ 0.2--0.3, for four rich clusters, and have suggested that the origin of metals in an intra-cluster medium (ICM) is not a type-Ia supernovae (SNIa), but a type-II supernovae (SNII). However, these authors used the solar photospheric iron abundance for ASCA data reduction, while the meteoritic iron abundance is usually adopted in chemical-evolution studies. It is true that although the photospheric and meteoritic solar abundances are consistent for most of the elements, a serious discrepancy is known to exist for iron; indeed, the photospheric abundance of iron is N_Fe/N_H = 4.68* 10(-5) by number, while the meteoritic value is 3.24* 10(-5) . The argument concerning the relative roles of SNIa and SNII in ICM enrichment is quite sensitive to the precise values of [alpha /Fe], and one should use an identical solar iron abundance in data reduction as well as in theoretical arguments. We therefore adopt the meteoritic iron abundance, which is consistent with chemical-evolution studies, and shift Mushotzky et al.'s ASCA data by Delta [alpha /Fe] =~ - -0.16 dex. By comparing the corrected [alpha /Fe] values with theoretical nucleosynthesis prescriptions of SNIa and SNII, we reach a conclusion that an SNIa iron contribution of 50% or higher in the ICM enrichment could not be ruled out, and might indeed be favored based on the ASCA spectra.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- February 1997
- DOI:
- 10.1093/pasj/49.1.1
- arXiv:
- arXiv:astro-ph/9702036
- Bibcode:
- 1997PASJ...49....1I
- Keywords:
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- GALAXIES: ELLIPTICAL;
- GALAXIES: EVOLUTION;
- GALAXIES: INTERGALACTIC MEDIUM;
- GALAXIES: X-RAYS;
- SUPERNOVAE;
- Astrophysics
- E-Print:
- 8 pages, 2 figures, requires PASJ LaTeX macros. To appear in PASJ