Coronal line emission in cluster cooling flows

Abstract

view Abstract Citations (15) References (42) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Coronal Line Emission in Cluster Cooling Flows Donahue, Megan ; Stocke, John T. Abstract We report one marginal detection (PKS 0745-191) and four nondetections (A2199, 2A0335 +096, A2597, and A1795) of the coronal emission line [Fe x] 6374 A radiated by ~10^6^ K gas in the central regions of massive cooling flow clusters (mass cooling rates of M >= 100 M_sun_ yr^-1^). Except for the nondetection of [Fe x] in A1795, these observations are consistent with and more sensitive than previous upper limits for these and similar clusters of galaxies. We discuss in detail the specific difficulties in detecting this emission line against the starlight and the ~10^4^ K emission-line region of the central cD. The [Fe x] emission directly probes the radiative behavior of cooling gas in the central 10 kpc of the cluster, which X-ray telescopes cannot yet spatially resolve. The [Fe x] detection in PKS 0745 - 191 cannot be explained by any plausible photoionization or gas heating model for cluster gas, except for the standard cooling gas picture. The [Fe x] luminosity measures (1) the cooling rate of gas in the centers of these clusters, and (2) the amount of photoionizing UV radiation that is generated by cooling gas. Such UV radiation can photoionize and heat the luminous, cool (~10^4^ K) filaments. The level of the detection and upper limits reported here suggest that a fraction (<~ 30%) of the rate of mass cooling observed by X-ray telescopes over extents of 100 kpc occurs in the central 10 kpc, and thus within the central cD itself. In addition, the [Fe x] strength is consistent with models for photoionizing the 10^4^ K nebular filaments by cooling hot gas (e.g., self-ionized cooling filaments, turbulent mixing layers, or stripped interstellar medium photoionized by cooling gas), although upper limits a few times more sensitive than the limits presented here would challenge the simplest of these models. Publication: The Astrophysical Journal Pub Date: February 1994 DOI: 10.1086/173741 Bibcode: 1994ApJ...422..459D Keywords: Cooling Flows (Astrophysics); Coronas; Emission Spectra; Galactic Clusters; Iron; Line Spectra; Elliptical Galaxies; Gas Dynamics; Gas Flow; X Ray Spectra; X Ray Telescopes; Astronomy; GALAXIES: COOLING FLOWS; GALAXIES: CLUSTERING full text sources ADS | data products SIMBAD (8) NED (7) Related Materials (1) Erratum: 1995ApJ...446..909D