A 700-pc extended coronal gas emission in the Circinus galaxy

We report the first characterization of an extended outflow of high ionized gas in the Circinus Galaxy by means of the coronal line [FeVII] $λ$6087 Å. This emission is located within the ionization cone already detected in the [OIII] $λ$5007 Å line and is found to extend up to a distance of 700 pc from the AGN. The gas distribution appears clumpy, with several knots of emission. Its kinematics is complex, with split profiles and line centroids shifted from the systemic velocity. The physical conditions of the gas show that the extended coronal emission is likely the remnants of shells inflated by the passage of a radio-jet. This scenario is supported by extended X-ray emission, which is spatially coincident with the morphology and extension of the [FeVII] $λ$6087~Å gas in the NW side of the galaxy. The extension of the coronal gas in the Circinus galaxy is unique among active galaxies and demonstrates the usefulness of coronal lines for tracing the shock ionization component in these objects.

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