We used 13 years of Swift/BAT observations to probe the nature and origin of hard X-ray (14-195 KeV) emission in Centaurus A. Since the beginning of the Swift operation in 2004, significant X-ray variability in the 14-195 KeV band is detected, with mild changes in the source spectrum. Spectral variations became more eminent after 2013, following a softer-when-brighter trend. Using the power spectral density method, we found that the observed hard X-ray photon flux variations are consistent with a red-noise process of slope, −1.3 with no evidence for a break in the PSD. We found a significant correlation between hard X-ray and 230 GHz radio flux variations, with no time delay longer than 30 days. The temporal and spectral analysis rules out the ADAF (advection-dominated accretion flow) model, and confirms that the hard X-ray emission is produced in the inner regions of the radio jet.
@article{arxiv.2205.07438,
title = {Hard X-ray emission in Centaurus A},
author = {B. Rani and S. A. Mundo and R. Mushotzky and A. Y. Lien and M. A. Gurwell and J. Y. Kim},
journal= {arXiv preprint arXiv:2205.07438},
year = {2022}
}