Multi-wavelength Flux and Polarization Variability of OJ 248 During 2011–2014 Outburst

Abstract We collected multi-wavelength light curves (from MJD 55500 to 57000) and polarization data (PD) (from MJD 55000 to 57000) of the flat-spectrum radio quasar OJ 248 to investigate the location and acceleration mechanism of the emission region within its jet. The study revealed that the optical PD reached peak values of (18.09 ± 0.09)% and (15.71 ± 0.07)% at MJD 56214 and MJD 56304, respectively, while no noticeable variation was observed in radio PD. Moreover, the light curves across different bands displayed varying degrees of variability. The average PD at 1 mm is consistently higher than that at 3 mm in each activity period, indicating an energy-dependent trend in PD, with the degree gradually decreasing from higher to lower energies. The relationship between PD and the fluxes in the R and V bands reveals a positive correlation. Given that the variations in optical PD were accompanied by multi-band flux variations, we employed the interpolation cross-correlation function to conduct a time lag analysis, thereby constraining the relative locations of radiation regions across different wavelength bands within the jet. Interestingly, the optical emission region is inferred to be located upstream of the X-ray emitting region. The dramatic increase in optical PD can be explained by a shock-in-jet model. Radiation originating from regions near the shock front becomes more highly polarized as a result of the ordered magnetic field produced by shock compression.