Constraining the Outburst Properties of the Radio Galaxy NGC 1316.

Combined Spitzer, Chandra, XMM-Newton, and VLA observations of the radio elliptical galaxy NGC 1316 (Fornax A) show features indicative of an AGN outburst most likely triggered by a merger with a galaxy whose gas mass was ∼4×10⁹ M⊙ about 0.4 Gyr ago. X-ray cavities in both the Chandra and XMM-Newton images likely result from the radio jet and the expansion of the radio lobes. The dust emission seen at 5.8 μm, 8.0 μm, and 24 μm is strongest in regions with little or no radio emission, suggesting that the expanding radio jet removes or destroys the dust as well as the hot gas. These results impose constraints on the properties of the outburst and the merger galaxy. The present size of the radio lobes implies the outburst is at least 0.4 Gyr old. The size of the X-ray cavities implies a minimum outburst energy of 1.2×10⁵⁸ ergs. The inferred dust mass implies that the outburst progenitor had a gas mass of ∼4×10⁹ M⊙. [ABSTRACT FROM AUTHOR]