PoS - Proceedings of Science
Volume 395 - 37th International Cosmic Ray Conference (ICRC2021) - GAD - Gamma Ray Direct
Exploring the variability properties of gamma-ray emission from blazars
G. Bhatta* and N. Dhital
Full text: pdf
Pre-published on: July 26, 2021
Published on: March 18, 2022
We present results of variability study of a sample of 20 powerful blazars using Fermi/LAT (0.1–
300 GeV) observations. We studied decade-long observations applying various analysis tools
such as flux distribution, symmetry analysis, and RMS-flux relation. It was found that the 𝛾-
ray flux distribution closely resembles a log-normal probability distribution function and can be
characterized by linear RMS-flux relation. The power spectral density analysis shows the statistical
variability properties of the sources as studied are consistent with flicker noise, an indication of
long-memory processes at work. Statistical analysis of the distribution of flux rise and decay
rates in the light curves of the sources, aimed at distinguishing between particle acceleration and
energy-dissipation timescales, counter-intuitively suggests that both kinds of rates follow a similar
distribution and the derived mean variability timescales are on the order of a few weeks. The
corresponding emission region size is used to constrain the location of 𝛾-ray production sites in
the sources to be a few parsecs. Additionally, using Lomb-Scargle periodogram and weighted
wavelet z-transform methods and extensive Monte Carlo simulations, we detected year-timescale
quasi-periodic oscillations in the sources S5 0716+714, Mrk 421, ON +325, PKS 1424-418, and
PKS 2155-304. We also performed recurrence quantification analysis of the sources and directly
measure the deterministic quantities, which suggest that the dynamical processes in blazars could
be a combination of deterministic and stochasti
DOI: https://doi.org/10.22323/1.395.0606
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