Mass-invariance of the iron enrichment in the hot haloes of massive ellipticals, groups, and clusters of galaxies

F. Mernier, J. Plaa, N. Werner, J. S. Kaastra, A. J. J. Raassen, L. Gu, J. Mao, I. Urdampilleta, N. Truong, A. Simionescu

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Abstract

X-ray measurements find systematically lower Fe abundances in the X-ray emitting haloes pervading groups ($kT\lesssim1.7$ keV) than in clusters of galaxies. These results have been difficult to reconcile with theoretical predictions. However, models using incomplete atomic data or the assumption of isothermal plasmas may have biased the best fit Fe abundance in groups and giant elliptical galaxies low. In this work, we take advantage of a major update of the atomic code in the spectral fitting package SPEX to re-evaluate the Fe abundance in 43 clusters, groups, and elliptical galaxies (the CHEERS sample) in a self-consistent analysis and within a common radius of 0.1$r_{500}$. For the first time, we report a remarkably similar average Fe enrichment in all these systems. Unlike previous results, this strongly suggests that metals are synthesised and transported in these haloes with the same average efficiency across two orders of magnitude in total mass. We show that the previous metallicity measurements in low temperature systems were biased low due to incomplete atomic data in the spectral fitting codes. The reasons for such a code-related Fe bias, also implying previously unconsidered biases in the emission measure and temperature structure, are discussed.
Original languageEnglish
Pages (from-to)L116–L121
Number of pages6
JournalMonthly Notices of the Royal Astronomical Society
Volume478
Issue number1
Early online date5 May 2018
DOIs
Publication statusE-pub ahead of print - 5 May 2018

Keywords

  • astro-ph.GA
  • galaxies
  • clusters
  • intracluster medium –X-rays
  • clusters – X-rays

Cite this

Mernier, F., Plaa, J., Werner, N., Kaastra, J. S., Raassen, A. J. J., Gu, L., Mao, J., Urdampilleta, I., Truong, N., & Simionescu, A. (2018). Mass-invariance of the iron enrichment in the hot haloes of massive ellipticals, groups, and clusters of galaxies. Monthly Notices of the Royal Astronomical Society, 478(1), L116–L121. https://doi.org/10.1093/mnrasl/sly080