Chandra Observations of NGC 4636—an Elliptical Galaxy in Turmoil

Chandra images show symmetric, 8 kpc long, armlike features in the X-ray halo surrounding NGC 4636. The leading edges of these features are sharp and are accompanied by temperature increases of ∼30%. These properties suggest that the armlike structures are produced by shocks, driven by symmetric off-center outbursts. We interpret these observations as part of a cycle in which the cooling gas originally fueled a nuclear outburst about 3 × 106 yr ago that led to shocks reheating the cooling gas and thus preventing the accumulation of significant amounts of cooled gas in the galaxy center and temporarily starving the central active galactic nucleus.