Implications of multiwavelength spectrum on cosmic-ray acceleration in blazar TXS 0506+056

MAGIC collaboration has recently analyzed data from a long-term multiwavelength campaign of the $\gamma$-ray blazar TXS 0506+056. In December 2018, it was flaring in very-high-energy (VHE; $E>100$ GeV) band, but no simultaneous neutrino event detected. We model observed spectral energy distribution (SED), using one-zone leptohadronic emission. estimate flux through restriction X-ray on secondary radiation due to hadronic cascade, initiated by protons with $E_p \lesssim 0.1$ EeV. assume ultrahigh-energy cosmic rays (UHECRs; $E\gtrsim0.1$ EeV), same slope and normalization as low-energy spectrum, are accelerated jet escape efficiently. propagate UHE random, turbulent extragalactic magnetic field (EGMF). The leptonic emission dominates GeV range, whereas cascade CR interactions contributes substantially VHE range. line-of-sight cosmogenic $\gamma$ UHECRs produce hardening spectrum. Our prediction for neutrinos is consistent 7.5-year limit IceCube shows variability during campaign. Therefore, we infer that correlation between GeV-TeV $\gamma$-rays flare minimal. luminosity CRs limits flux, which, turn, bounds RMS value EGMF $\gtrsim 10^{-5}$ nG. lower than IceCube-Gen2 detection potential 10 yrs observation. should arise increased activity inside jet; thus, detecting steady at multi-TeV energies may indicate UHECR acceleration. Upcoming imaging telescopes such CTA will be able constrain component SED