Centaurus A: Hard X-ray and High-Energy Gamma-Ray Light Curve Correlation
Abstract
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 (γ) 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 γ rays by 25±125 days. If this lag is real and related to a γγ 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 γ rays and X-rays from Centaurus A.
- Publication:
-
Galaxies
- Pub Date:
- April 2019
- DOI:
- 10.3390/galaxies7020044
- Bibcode:
- 2019Galax...7...44D
- Keywords:
-
- active galactic nucleus;
- radio galaxy;
- Centaurus A;
- GeV γ-rays;
- TeV γ-rays;
- light curve;
- discrete correlation function