@article {40023,
	title = {A Two-zone Model for Blazar Emission: Implications for TXS 0506+056 and the Neutrino Event IceCube-170922A},
	volume = {886},
	year = {2019},
	month = {2019/11/1},
	pages = {23},
	publisher = {IOP},
	abstract = {A high-energy muon neutrino event, IceCube-170922A, was recently discovered in both spatial and temporal coincidence with a gamma-ray flare of the blazar TXS 0506+056. It has been shown with standard one-zone models that neutrinos can be produced in the blazar jet via hadronic interactions, but with a flux that is mostly limited by the X-ray data. In this work, we explore the neutrino production from TXS 0506+056 by invoking two physically distinct emission zones in the jet, with an inner blob inside of or close to the broad-line region (BLR) and an outer one well beyond the BLR. Using the Doppler-boosted radiation of the BLR as the target photon field, the inner zone accounts for the neutrino and gamma-ray emission via pγ interactions and inverse Compton scattering, respectively, while the outer zone produces the optical and X-ray emission via synchrotron and synchrotron self-Compton processes. The different conditions of the two zones allow us to suppress the X-ray emission from the electromagnetic cascade, and set a much higher upper limit on the muon neutrino flux (i.e., \~{}10<SUP>-11</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>) than in one-zone models. We compare our scenario in detail with one-zone models discussed in the literature, and argue that differentiating between such scenarios will become possible with next-generation neutrino telescopes, such as IceCube-Gen2.},
	keywords = {1100, 164, 633, 731, 739, Astrophysics - High Energy Astrophysical Phenomena, Blazars, Gamma-ray sources, High energy astrophysics, High-energy cosmic radiation, Neutrino astronomy},
	isbn = {0004-637X},
	url = {https://ui.adsabs.harvard.edu/abs/2019ApJ...886...23X},
	author = {Xue, Rui and Liu, Ruo-Yu and Petropoulou, Maria and Oikonomou, Foteini and Wang, Ze-Rui and Wang, Kai and Wang, Xiang-Yu}
}
