arXiv subjects

Michael Loewenstein

Publications and source records attributed to Michael Loewenstein.

75 records · Page 5Linked to original sources

arXiv1997

Reply to ``Roles of SNIa and SNII in ICM Enrichment'' by Y. Ishimaru and N. Arimoto

We address a number of misunderstandings and misstatements contained in the paper ``Roles of SNIa and SNII in ICM Enrichment'' by Y. Ishimaru and N. Arimoto with regard to the papers by Mushotzky et al. (1996, ApJ, 466, 686) and Loewenstein and Mushotzky (1996, ApJ, 466, 695). In particular, we emphasize that comparison between observations and models in these papers were made self-consistently assuming a particular (photospheric) value for the solar iron abundance. We also briefly revisit the question of the contribution of Type Ia supernovae to the iron enrichment of the intracluster medium.

astro-ph↗

arXiv1997

Lack of Evolution in the Iron Abundance in Clusters of Galaxies and Implications for the Global Star Formation Rate at High Redshift

We present the first large sample of accurate iron abundances and temperatures for clusters at redshifts greater than 0.14. We find that the Fe abundance shows little or no evolution out to redshift 0.3. This and the early formation epoch of elliptical galaxies in clusters indicate that most of the enrichment of the intracluster medium occurred at redshifts greater than 1. If clusters represent fair samples of the universe, then global metal production is 2-5 times greater than is inferred from recent studies of galaxies at low and high redshifts.

astro-ph↗

arXiv1996

The Mass of Abell 1060 and AWM 7 from Spatially Resolved X-ray Spectroscopy: Variations in Baryon Fraction

Using X-ray temperature and surface brightness profiles of the hot intracluster medium derived from ASCA and ROSAT observations we place constraints on the dark matter and baryon fraction distributions in the poor clusters Abell 1060 and AWM 7. Although their total mass distributions are similar, AWM 7 has twice the baryon fraction of Abell 1060 in the best-fit models. The functional form of the dark matter distribution is ill-determined, however mass models where the baryon fractions in Abell 1060 and AWM 7 significantly overlap are excluded. Such variations in baryon fraction are not predicted by standard models and imply that some mechanism in addition to gravity plays a major role in organizing matter on cluster scales.

astro-ph↗