http://arxiv.org/abs/1807.11069
The association of the high-energy neutrino event IceCube-170922A with the flaring blazar TXS~0506+056 indicates that hadronic processes may operate in a blazar jet. We perform semi-analytical spectral fitting of the multi-wavelength emission to obtain estimates of the jet physical parameters, and find that the multi-wavelength emission can be explained by either a proton synchrotron scenario or an electron inverse Compton scattering scenario. In the proton synchrotron scenario, a strong magnetic field of $10-100$~G is required, implying that the particle acceleration is likely driven by magnetic energy dissipation such as magnetic reconnection events. The inverse Compton scenario implies a magnetic field of $0.1-1$~G. Thus the particle acceleration is likely driven by the kinetic energy dissipation such as shocks. We also discuss the neutrino production in the context of single-zone and multi-zone models based on the above two scenarios. We demonstrate that the variability and optical polarization signatures can be used to distinguish the two scenarios due to their drastically different magnetic field. Specifically, the proton synchrotron scenario may show orphan fast variability in the low-energy spectral component on top of the active state, with an optical polarization degree $\lesssim 10\%$ throughout the active state. The inverse Compton scattering scenario instead predicts co-variability of the low- and high-energy components on both short and long time scales, as well as a strongly variable optical polarization degree that can reach $\gtrsim 20\%$. Our results suggest that optical polarization measurements and well-resolved multi-wavelength light curves can be used to understand the electromagnetic and high-energy neutrino emissions by TXS~0506+056 and similar events in the future.
H. Zhang, K. Fang and H. Li
Tue, 31 Jul 18
48/69
Comments: Submitted to The Astrophysical Journal
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