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تسجيل مستخدم جديدExploring the Nature of the 2016 {gamma}-ray Emission in the Blazar 1749+096
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Recent Fermi-Large Area Telescope (LAT) light curves indicate an active $gamma$-ray state spanning about five months from 2016 June to 2016 October in the BL Lac object 1749+096 (OT 081). During this period, we find two notable $gamma$-ray events: an exceptionally strong outburst followed by a significant enhancement (local peak). In this study, we analyze multi-waveband light curves (radio, optical, X-ray, and $gamma$-ray) plus very-long baseline interferometry (VLBI) data to investigate the nature of the $gamma$-ray events. The $gamma$-ray outburst coincides with flux maxima at longer wavelengths. We find a spectral hardening of the $gamma$-ray photon index during the $gamma$-ray outburst. The photon index shows a transition from a softer-when-brighter to a harder-when-brighter trend at around 1.8 $times$ $10^{-7}$ ph cm$^{-2}$ s$^{-1}$. We see indication that both the $gamma$-ray outburst and the subsequent enhancement precede the propagation of a polarized knot in a region near the VLBI core. The highest polarized intensity, 230,mJy, and an electric vector position angle rotation, by $sim$32$^{circ}$, are detected about 12 days after the $gamma$-ray outburst. We conclude that both $gamma$-ray events are caused by the propagation of a disturbance in the mm-wave core.
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