Speaker
Description
The search for periodicity in the multi-wavelength high variable emission of blazars is a key feature to understand dynamical processes
at work in this class of active galactic nuclei. The blazar PG 1553+113 is an attractive target due to the evidence of periodic oscillations
observed at different wavelengths, with a solid proof of a 2.2-year modulation detected in the γ-ray, UV and optical bands. We aim
at investigating the variability pattern of the PG 1553+113 X-ray emission using a more than 10-years long light curve, in order to
robustly assess the presence or lack of a periodic behavior whose evidence is only marginal so far. We conducted detailed statistical
analyses, studying in particular the variability properties of the X-ray emission of PG 1553+113 by computing the Lomb-Scargle
periodograms, which are suited for the analyses of unevenly sampled time series, and adopting epoch folding techniques. We find out
a modulation pattern in the X-ray light curve of PG 1553+113 with a period of ∼1.4 years, about 35% shorter than the one observed
in the γ-ray domain. Our finding is in agreement with the recent spectro-polarimetric analyses and supports the presence of more
dynamical phenomena simultaneously at work in the central engine of this quasar.
