4-year optical-infrared photometric and polarimetric behaviors of a gamma-ray blazar 3C 454.3

摘要

We have performed a multi-color photo-polarimetric monitoring of 45 optical-bright blazars since 2007.3C 454.3, which is one of the brightest blazars in the gamma-ray sky, is one of targets of its project. We have made photo-polarimetric monitorings since July 2007. The object showed violent variation in its flux and polarization. In particular, four large-amplitude outbursts in 2007, 2008, 2009 and 2010 are remarkable. In each outburst, we observed a significant rise in the polarization degree. We calculated structure functions of the total flux and polarization from the 4-year monitoring data. In this time, we estimate the systematic and statistical errors of its structure functions. We adopt these errors when we estimate the break time-scales. The break time-scale of the total flux in 3C 454.3 is longer than that of the polarization. We also calculate the structure functions from total flux and polarization of the 15 blazars which are high-frequency monitored, and estimate the break time-scales. Most of estimated break time-scales of the total fluxes are longer than that of the polarization. From these results, it is indicated that the break time-scale of the total flux is reflected to the larger-amplitude and longer variation, like the outburst. However, the break time-scale of the polarization is related to the time-scale of the day-scale flares.