Buoyant AGN Bubbles in the Quasi-isothermal Potential of NGC 1399


The Fornax Cluster is a low-mass cool-core galaxy cluster. We present a deep Chandra study of NGC. 1399, the central dominant elliptical galaxy of Fornax. The cluster center harbors two symmetric X-ray cavities coincident with a pair of radio lobes fed by two collimated jets along a north-south axis. A temperature map reveals that the active galactic nucleus (AGN) outburst has created a channel filled with cooler gas out to a radius of 10 kpc. The cavities are surrounded by cool bright rims and filaments that may have been lifted from smaller radii by the buoyant bubbles. X-ray imaging suggests a potential ghost bubble of. 5 kpc diameter to the northwest. We find that the amount of gas lifted by AGN bubbles is comparable to that which would otherwise cool, demonstrating that AGN-driven outflow is effective in offsetting cooling in low-mass clusters. The cluster cooling timescale is > 30 times longer than the dynamical timescale, which is consistent with the lack of cold molecular gas at the cluster center. The X-ray hydrostatic mass is consistent within 10%, with the total mass derived from the optical data. The observed entropy profile rises linearly, following a steeper slope than that observed at the centers of massive clusters; gas shed by stars in NGC. 1399 may be incorporated in the hot phase. However, it is far-fetched for supernova-driven outflow to produce and maintain the thermal distribution in NGC. 1399, and it is in tension with the metal content in the hot gas.

galaxies: clusters: intracluster medium, ISM: bubbles, X-rays: galaxies: clusters, X-RAY-EMISSION, ELLIPTIC GALAXIES, MOLECULAR GAS, COOLING TIME, COLD GAS, HOT GAS, CLUSTER, NGC-1399, CAVITIES, FEEDBACK, Astronomy & Astrophysics
Su, Y. et al. (2017): Buoyant AGN Bubbles in the Quasi-isothermal Potential of NGC 1399. The Astrophysical Journal, 847(2). DOI: 10.3847/1538-4357/aa8954