1998/04/30 by David A. Buote, C. R. Canizares, Claude R. Canizares +1 · 2 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.1999.02969.x
published as Mon.Not.Roy.Astron.Soc.310:483,1999 · 30 pages (18 figures), To Appear in MNRAS. Major revision of the initially posted version: (1) The section on ASCA data of ellipticals was expanded and moved to astro-ph/9811080; (2) The ASCA data of M87, Centaurus, and Perseus have been re-analyzed. We find evidence for Fe K-beta emission in these systems, but the Fe K-beta/K-alpha ratios do not suggest resonance scattering; (3) The metal abundances of the cores of these systems are consistent with the meteoritic solar values
arxiv created 1999/07/12 · openalex publication_date 1999/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We examine the K shell emission lines produced by isothermal and simple multiphase models of the hot gas in elliptical galaxies and galaxy clusters to determine the most effective means for constraining the width of the differential emission measure, ξ(T ), in these systems which we characterize by a dimensionless parameter, σ. Comparison of line ratios of two-temperature (σ<1) and cooling flow (σ∼1) models is presented in detail. We find that a two-temperature model can approximate very accurately a cooling flow spectrum over 0.5–10 keV. We re-analyse the ASCA spectra of three of the brightest galaxy clusters to assess the evidence for multiphase gas in their cores: M87 (Virgo), the Centaurus cluster and the Perseus cluster. Kα emission-line blends of Si, S, Ar, Ca and Fe are detected in each system, as is significant Fe Kβ emission. The Fe Kβ/Kα ratios are consistent with optically thin plasma models and do not suggest resonance scattering in these systems. Consideration of both the ratios of H-like to He-like Kα lines and the local continuum temperatures clearly rules out isothermal gas in each case. To obtain more detailed constraints, we fitted plasma models over 1.6–9 keV where the emission is dominated by these K shell lines and by continuum. In each case the ASCA spectra cannot determine whether the gas emits at only two temperatures or over a continuous range of temperatures as expected for a cooling flow. The metal abundances are near-solar for all of the multiphase models. We discuss the implications of these results and examine the prospects for determining the temperature structure in these systems with upcoming X-ray missions.