Gamma-ray blazar variability: new statistical methods of time-flux distributions

ABSTRACT Variable γ-ray emission from blazars, one of the most powerful classes astronomical sources featuring relativistic jets, is a widely discussed topic. In this work, we present results variability study sample 20 blazars using (0.1–300 GeV) observations Fermi/LAT telescope. Using maximum likelihood estimation (MLE) methods, find that probability density functions best describe blazar flux distributions use stable distribution family, which generalizes Gaussian distribution. The suggest average behaviour over period can be characterized by log-stable distributions. For sources, estimate leads to standard lognormal (α = 2). However, few clearly display heavy tail (MLE α < 2), suggesting underlying multiplicative processes infinite variance. Furthermore, light curves were analysed employing novel non-stationarity and autocorrelation analyses. former analysis allowed us quantitatively evaluate in each source – finding forgetting rate (corresponding decay time) maximizing log-likelihood for modelled evolution functions. Additionally, evaluation local allows detect anomalies, transient nature some statistical properties curves. With analysis, examined lag dependence all {(yt, yt + l)} points, described various mixed moments, allowing multiple characteristic time scales implying possible hidden periodic processes.