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Open AccessArticle

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

1
Department of Physics, University of Namibia, Private Bag 13301, Windhoek 12010, Namibia
2
Centre for Space Research, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa
*
Author to whom correspondence should be addressed.
Galaxies 2019, 7(2), 44; https://doi.org/10.3390/galaxies7020044
Received: 26 February 2019 / Revised: 25 March 2019 / Accepted: 27 March 2019 / Published: 4 April 2019
(This article belongs to the Special Issue Radio Galaxies at TeV Energies)
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 γ γ 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. View Full-Text
Keywords: active galactic nucleus; radio galaxy; Centaurus A; GeV γ-rays; TeV γ-rays; light curve; discrete correlation function active galactic nucleus; radio galaxy; Centaurus A; GeV γ-rays; TeV γ-rays; light curve; discrete correlation function
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Davids, I.D.; Böttcher, M.; Backes, M. Centaurus A: Hard X-ray and High-Energy Gamma-Ray Light Curve Correlation. Galaxies 2019, 7, 44.

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