Optical polarization variations in the blazar PKS 1749+096

Uemura, M., Itoh, R., Liodakis, I., Blinov, D., Nakayama, M., Xu, L., Sawada, N., Wu, H.-Y., and Fujishiro, I., “Optical polarization variations in the blazar PKS 1749+096”, PASJ, 69, 96, 2017

We report on the variation in the optical polarization of the blazar PKS 1749+096. The object favors a polarization angle (PA) of 40°-50° at the flare maxima, which is close to the position angle of the jet (20°-40°). Three clear polarization rotations were detected in the negative PA direction associated with flares. The light-curve maxima of the flares possibly tended to lag behind the PD maxima and color-index minima. We propose a scenario to explain these observational features, where transverse shocks propagate along curved trajectories. The favored PA at the flare maxima suggests that the observed variations were governed by the variations in the Doppler factor, δ. Based on this scenario, the minimum viewing angle of the source, θ _min = 4.8°-6.6°, and the location of the source, Δr ≳ 0.1 pc, from the central black hole were estimated. The combined effect of the variation in δ and acceleration/cooling of electrons is probably responsible for the observed diversity of the polarization variations in the flares.