Detection of optical coronal emission from 10^6 K gas in the core of the Centaurus cluster

Abstract

We report a detection (3.5x10^37 \pm 5.6x10^36 ergps) of the optical coronal emission line [Fe X]6374 and upper limits of four other coronal lines using high resolution VIMOS spectra centred on NGC 4696, the brightest cluster galaxy in the Centaurus cluster. Emission from these lines is indicative of gas at temperatures between 1 and 5 million K so traces the interstellar gas in NGC 4696. The rate of cooling derived from the upper limits is consistent with the cooling rate from X-ray observations (~10 solar masses per year) however we detect twice the luminosity expected for [Fe X]6374 emission, at 1 million K, our lowest temperature probe. We suggest this emission is due to the gas being heated rather than cooling out of the intracluster medium. We detect no coronal lines from [Ca XV], which are expected from the 5 million K gas seen near the centre in X-rays with Chandra. Calcium is however likely to be depleted from the gas phase onto dust grains in the central regions of NGC 4696.

11 pages, 13 figures, 2 tables, accepted for publication in MNRAS

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Cited by in corpus (10)

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• Constraining Gas Motions in the Intra-Cluster Medium
• Herschel observations of the Centaurus cluster - the dynamics of cold gas in a cool core
• Searching for the missing iron in the core of the Centaurus cluster
• A volume-limited sample of X-ray galaxy groups and clusters: III. Central abundance drops
• Revealing O VII from stacked X-ray grating spectra of clusters, groups and elliptical galaxies
• A deep spectroscopic study of the filamentary nebulosity in NGC4696, the brightest cluster galaxy in the Centaurus cluster
• Searching for FUV line emission from $10^7$ K gas in massive elliptical galaxies and galaxy clusters as a tracer of turbulent velocities
• Implications of Coronal Line Emission in NGC 4696
• Directly Imaging the Cooling Flow in the Phoenix Cluster