  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.
