Hadronic models of blazars require a change of the accretion paradigm

Abstract

We study hadronic models of broad-band emission of jets in radio-loud active galactic nuclei, and their implications for the accretion in those sources. We show that the models that account for broad-band spectra of blazars emitting in the GeV range in the sample of Böttcher et al. have highly super-Eddington jet powers. Furthermore, the ratio of the jet power to the radiative luminosity of the accretion disc is ∼ 3000 on average and can be as high as ∼ 10 5 . We then show that the measurements of the radio core shift for the sample imply low magnetic fluxes threading the black hole, which rules out the Blandford-Znajek mechanism to produce powerful jets. These results require that the accretion rate necessary to power the modelled jets is extremely high, and the average radiative accretion efficiency is ∼ 4 × 10 −5 . Thus, if the hadronic model is correct, the currently prevailing picture of accretion in AGNs needs to be significantly revised. Also, the obtained accretion mode cannot be dominant during the lifetimes of the sources, as the modelled very high accretion rates would result in too rapid growth of the central supermassive black holes. Finally, the extreme jet powers in the hadronic model are in conflict with the estimates of the jet power by other methods.

Active Galactic Nuclei as High-Energy Neutrino Sources

“…Instead, one can adopt lepto-hadronic scenarios, where gamma rays are attributed to proton synchrotron radiation or pγ-induced cascade emission, although huge CR luminosities are usually required. 54,55 In the lepto-hadronic scenarios, the relationship between the neutrino and photon luminosities is different. 56,57 One of the appealing points is that the neutrino flux can be calibrated by the gamma-ray flux, and the diffuse gamma-ray intensity could be explained simultaneously with the diffuse neutrino intensity at ∼ 1 PeV.…”

Multiband Observations of the Quasar PKS 2326–502 during Active and Quiescent Gamma-Ray States in 2010–2012

“…However, hadronic models are disfavored by energetics for many FSRQs and low-peaked BL Lac objects. The jet powers required to fit the SEDs are so high thatthey would require an accretion rate far greater than the prevailing idea of accretion in AGNs allows (Zdziarski & Böttcher 2015;Petropoulou & Dermer 2016).Some models invoke large numbers of emitting zones (Marscher 2014) while others invoke only a single (or a few) emitting regions (Dermer et al 2009). Leptonic models that use the synchrotron photons already present in the jet as the source of seed photons for inverse Compton scattering are referred to as synchrotron self-Compton (SSC) models (Maraschi & Tavecchio 2003).…”

Multi-TeV flaring from blazars: Markarian 421 as a case study

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