<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Mastichiadis, Apostolos</style></author><author><style face="normal" font="default" size="100%">Petropoulou, Maria</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Hadronic X-Ray Flares from Blazars</style></title><short-title><style face="normal" font="default" size="100%">The Astrophysical Journal</style></short-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">1100</style></keyword><keyword><style  face="normal" font="default" size="100%">1119</style></keyword><keyword><style  face="normal" font="default" size="100%">17</style></keyword><keyword><style  face="normal" font="default" size="100%">637</style></keyword><keyword><style  face="normal" font="default" size="100%">Active galaxies</style></keyword><keyword><style  face="normal" font="default" size="100%">Astrophysics - High Energy Astrophysical Phenomena</style></keyword><keyword><style  face="normal" font="default" size="100%">Gamma-rays</style></keyword><keyword><style  face="normal" font="default" size="100%">Neutrino astronomy</style></keyword><keyword><style  face="normal" font="default" size="100%">Non-thermal radiation sources</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2021</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2021/01/1</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://ui.adsabs.harvard.edu/abs/2021ApJ...906..131M</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">IOP</style></publisher><volume><style face="normal" font="default" size="100%">906</style></volume><pages><style face="normal" font="default" size="100%">131</style></pages><isbn><style face="normal" font="default" size="100%">0004-637X</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The detection of a high-energy neutrino from the flaring blazar TXS 0506+056 and the subsequent discovery of a neutrino excess from the same direction have strengthened the hypothesis that blazars are cosmic neutrino sources. The lack, however, of γ-ray flaring activity during the latter period challenges the standard scenario of correlated γ-ray and high-energy neutrino emission in blazars. We propose instead that TeV-PeV neutrinos are produced in coincidence with X-ray flares that are powered by proton synchrotron radiation. In this case, neutrinos are produced by photomeson interactions of protons with their own synchrotron radiation, while MeV to GeV γ-rays are the result of synchrotron-dominated electromagnetic cascades developed in the source. Using a time-dependent approach, we find that this &quot;pure hadronic flaring&quot; hypothesis has several interesting consequences. The X-ray flux is a good proxy for the all-flavor neutrino flux, while certain neutrino-rich X-ray flares may be dark in GeV-TeV γ-rays. Lastly, hadronic X-ray flares are accompanied by an equally bright MeV component that is detectable by proposed missions like e-ASTROGAM and AMEGO. We applied this scenario to the extreme blazar 3HSP J095507.9+355101 which has been associated with IceCube-200107A while undergoing an X-ray flare. We showed that the number of muon and anti-muon neutrinos above 100 TeV during hadronic flares can be up to ∼3-10 times higher than the expected number in standard leptohadronic models. Still, frequent hadronic flaring activity is necessary for explaining the detected neutrino event IceCube-200107A.</style></abstract></record></records></xml>