Abstract
The recent associations of neutrinos with blazars require the efficient interaction of relativistic protons with ambient soft photon fields. However, along side the neutrinos, γ-ray photons are produced, which interact with the same soft photon fields producing electron-positron pairs. The strength of this cascade has significant consequences on the photon spectrum in various energy bands and puts severe constraints on the pion and neutrino production. In this study, we discuss the influence of the external thermal photon fields (accretion disk, broad-line region, and dusty torus) on the proton-photon interactions, employing a newly developed time-dependent one-zone hadro-leptonic code OneHaLe. We present steady-state cases, as well as a time-dependent case, where the emission region moves through the jet. Within the limits of this toy study, the external fields can disrupt the “usual” double-humped blazar spectrum. Similarly, a moving region would cross significant portions of the jet without reaching the previously-found steady states.
Highlights
The theory of the blazar emission was transformed in the early 1990s by the introduction of the so-called external-Compton scenario
The broad-line region (BLR) and dusty torus (DT) are approximated as isotropic photon fields in the host galaxy frame within an distance RBLR and RDT from the black hole, and their energy distribution is given through a grey-body spectrum of temperature TBLR and TDT normalized to a luminosity of LBLR and LDT, respectively
The results of the toy study presented in this paper clearly show the importance of the external fields in case of the presence of relativistic protons in the jet
Summary
The theory of the blazar emission was transformed in the early 1990s by the introduction of the so-called external-Compton scenario. The scenario explains the high-energy component of the spectral energy distribution (SED) through relativistic electrons inverseCompton (IC) scattering soft, thermal photon fields that originate outside the jet. This transformation of blazar research was significantly driven by the works of Reinhard Schlickeiser and collaborators employing the accretion disk (AD) as a source for soft external photons [1–4]. We note that the study conducted is a toy model: In order to properly identify the influence of the external fields, all other parameters of the emission region remain the same, irrespective of the location This may have significant consequences for the emerging spectra.
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