Hadronic Correlated Flares from Mrk 501
  We discuss the possibility of explaining the extraordinary, correlated X-ray/TeV flares observed during April 1997 from Mrk 501, by synchrotron-pair cascades injected by synchrotron radiation from ultra-high energy protons and muons. Evaluating the jet conditions required to explain the observed features of the flares, the allowed region for this model in the parameter space of jet magnetic field and Doppler factor is identified, and compared with the parameter choices of other, both hadronic and leptonic models presented in the literature. The present model requires magnetic fields similar to other hadronic models for gamma-ray blazars (B >~ 30 G), but a lower Doppler factor (D =~ 3). 
Jorg P. Rachen (U Utrecht)