Active-galactic-nucleus-driven Weather and Multiphase Gas in the Core of the NGC 5044 Galaxy Group

A deep Chandra observation of the X-ray bright group, NGC 5044, shows that the central region of this group has been strongly perturbed by repeated active galactic nucleus (AGN) outbursts. These recent AGN outbursts have produced many small X-ray cavities, cool filaments, and cold fronts. We find a correlation between the coolest X-ray emitting gas and the morphology of the Hα filaments. The Hα filaments are oriented in the direction of the X-ray cavities, suggesting that the warm gas responsible for the Hα emission originated near the center of NGC 5044 and was dredged up behind the buoyant, AGN-inflated X-ray cavities. A detailed spectroscopic analysis shows that the central region of NGC 5044 contains spatially varying amounts of multiphase gas. The regions with the most inhomogeneous gas temperature distribution tend to correlate with the extended 235 MHz and 610 MHz radio emission detected by the Giant Metrewave Radio Telescope. This may result from gas entrainment within the radio emitting plasma or mixing of different temperature gas in the regions surrounding the radio emitting plasma by AGN-induced turbulence. Accounting for the effects of multiphase gas, we find that the abundance of heavy elements is fairly uniform within the central 100 kpc, with abundances of 60%-80% solar for all elements except oxygen, which has a significantly sub-solar abundance. In the absence of continued AGN outbursts, the gas in the center of NGC 5044 should attain a more homogeneous distribution of gas temperature through the dissipation of turbulent kinetic energy and heat conduction in approximately 10⁸ yr. The presence of multiphase gas in NGC 5044 indicates that the time between recent AGN outbursts has been less than ~10⁸ yr.