Multi-epoch leptohadronic modeling of neutrino source candidate blazar PKS 0735+178

Context. The origin of the astrophysical neutrino flux discovered by IceCube remains largely unknown. Several individual neutrino source candidates were observed. Among them is the gamma-ray flaring blazar TXS 0506+056. A similar coincidence of a high-energy neutrino and a gamma-ray flare was found in blazar PKS 0735+178. Aims. By modeling the spectral energy distributions of PKS 0735+178, we aimed to explore the physical conditions that lead to neutrino production at different stages of the source's activity. Methods. We analyzed the multiwavelength data from the selected time periods. Using numerical simulations of radiation processes in the source, we explored the parameter space of one-zone leptonic and leptohadronic models to find the best-fit solutions that explain the observed photon fluxes. Results. We demonstrated how model parameter degeneracy affected the prediction of neutrino spectra. We showed that the available multiwavelength data were insufficient to predict the neutrino spectrum unambiguously. However, under the condition of neutrino rates maximization, we proposed a scenario in which 0.1 neutrino events were produced during the 50-day flare.