Polarization variability of blazars in the optical emission

Abstract

Polarization studies in blazars are effective tools for analyzing the emission composition and the relativistic jet. In this work, we collected photometric and polarization data from the Steward Observatory Blazar Monitoring Program and performed the following studies. (1) Among the 10 target sources, 8 sources exhibit correlations between the polarization variability (\(P\)) and \(V\)-lightcurves (\(F_{V}\)). (2) When we use the multiorder power law function to fit \(P\) and \(F_{V}\), we obtain several parameters, including the brightening timescale (\(\Delta T_{b}\)) and the dimming timescale (\(\Delta T_{d}\)). In the brightening stage, \(\Delta T_{P|b}\) and \(\Delta T_{F|b}\) were correlated, with a correlation coefficient of \(r=0.45\), and a chance probability of \(p=0.30\%\). In the dimming stage, \(\Delta T_{P|d}\) and \(\Delta T_{F|d}\) exhibited weak correlations. (3) To analyze the origin of the polarization, we study the dependence of polarization on spectral index.