X-ray cavities, filaments, and cold fronts in the core of the galaxy group NGC 5044

Abstract

We present a two-dimensional analysis of the bright nearby galaxy group NGC 5044 using the currently available Chandra and XMM data. In the inner 10 kpc, a pair of cavities are evident together with a set of bright X-ray filaments. If the cavities are interpreted as gas displaced by relativistic plasma inflated by an active galactic nucleus, even in the absence of extended 1.4 GHz emission, this would be consistent with a recent outburst as also indicated by the extent of dust and Hα emission. The soft X-ray filaments coincident with Hα and dust emission are cooler than those which do not correlate with optical and infrared emission. We suggest that dust-aided cooling contributes to form warm (T ∼ 104 K) gas, emitting Hα radiation. At 31 kpc and 67 kpc, a pair of cold fronts are present, indicative of sloshing due to a dynamical perturbation caused by accretion of a less-massive group, also suggested by the peculiar velocity of the brightest galaxy NGC 5044 with respect to the mean group velocity.