Centaurus A: Hard X-ray and High-Energy Gamma-Ray Light Curve Correlation

Centaurus A, powered by a 55 million solar mass supermassive black hole, has been intensively monitored in all accessible wavelength ranges of the electromagnetic spectrum. However, its very-high energy gamma (gamma) ray flux (TeV photons), obtained from H.E.S.S. is relatively faint, hampering detailed light curve analyses in the most energetic energy band. Yet, the extensive long-term light curve data from Fermi-LAT and Swift-BAT (hard X-rays) allows for cross-correlation studies. We find a hint that X-ray emission from Centaurus A precedes the gamma rays by 25 +/- 125 days. If this lag is real and related to a gamma gamma absorption effect in the broad-line region (BLR) around the central source, we can constrain the size of the BLR using light-travel time arguments. These are first results of extended light curve correlation studies between high-energy gamma rays and X-rays from Centaurus A.