Speaker: Gopal Bhatta

Title: “Exploring blazar jets with multi-wavelength and multi-timescale variability studies”

Abstract:
Blazars are a subclass of radio-loud active galactic nuclei featuring relativistic jets closely aligned to the direction of the Earth. The sources exhibit some of the extreme properties such high luminosity, strong polarization, and variability over a wide range of observable frequencies and in all timescales. In this presentation, I discuss some of the results from our variability studies employing several methods of time series analysis on the radio, optical, X-rays and gamma rays observations of a sample of gamma-ray bright blazars. The results indicate that the sources are highly variable in the timescale ranging from a few hours to decades. The statistical properties of the variability can be characterized by a single power-law in the logarithmic frequency-power plane. Furthermore, the gamma-ray flux distribution display a linear RMS-flux relation and can be well represented by log-normal probability distribution function. The results imply that the gamma ray flux variability could be driven by long-memory processes representing non-linear multiplicative processes at the disk-jet interface. Apart from the generic aperiodic variability, we also detected quasi-periodic oscillations in some of the sources.