Statistical analysis of micro-variability properties of the blazar S5 0716+714

TL;DR

This study analyzes multi-band optical observations of blazar S5 0716+714 from 2011 to 2018, supporting a turbulence-based model for micro-variability with consistent time lag predictions and log-normal flare distributions.

Contribution

It develops an automatic model fitting method for micro-variability and confirms the turbulence model's predictions using multi-frequency observational data.

Findings

Turbulent cell sizes range from 5 to 55 AU.

Micro-variability flares follow a log-normal distribution.

Time lags between bands are several minutes, consistent with the turbulence model.

Abstract

The typical blazar S5 0716$+$714 is very interesting due to its rapid and large amplitude variability and high duty cycle of micro-variability in optical band. We analyze the observations in I, R and V bands obtained with the $1.0m$ telescope at Weihai observatory of Shandong University from 2011 to 2018. The model of synchrotron radiation from turbulent cells in a jet has been proposed as a mechanism for explaining micro-variability seen in blazar light curves. Parameters such as the sizes of turbulent cells, the enhanced particle densities, and the location of the turbulent cells in the jet can be studied using this model. The model predicts a time lag between variations as observed in different frequency bands. Automatic model fitting method for micro-variability is developed, and the fitting results of our multi-frequency micro-variability observations support the model. The results show that both the amplitude and duration of flares decomposed from the micro-variability light curves confirm to the log-normal distribution. The turbulent cell size is within the range of about 5 to 55 AU, and the time lags of the micro-variability flares between the I-R and R-V bands should be several minutes. The time lags obtained from the turbulence model are consistent with the fitting statistical results, and the time lags of flares are correlated with the time lags of the whole light curve.