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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]

Since ultraluminous X-ray sources are typically found in late-type systems, particularly in interacting or starburst galaxies, they are thought to be associated with young stellar populations. We find a significant population of ULXs in our sample of 94 nearby elliptical and lenticular galaxies, using the superior resolution of the Chandra X-ray observatory, far exceeding the number expected from background AGN. We show that though some of these ULXs are associated with young stellar populations in the cores of early-type galaxies, not all of the host galaxies show evidence of recent or ongoing star formation. We suggest that these ULXs come from a variety of sources, some being bright LMXBs, while some of them correspond to nuclei of recently accreted dwarf galaxies. [ABSTRACT FROM AUTHOR]