A hadronic origin for ultra-high-frequency-peaked BL Lac objects

By M. Cerruti, Andrea Zech, Catherine Boisson, S. Inoue. 2014

196 citations recorded by the source corpus.

Current Cherenkov telescopes have identified a population of ultra-high-frequency peaked BL Lac objects (UHBLs), also known as extreme blazars, that exhibit exceptionally hard TeV spectra, including 1ES 0229+200, 1ES 0347-121, RGB J0710+591, 1ES 1101-232, and 1ES 1218+304. Although one-zone synchrotron-self-Compton (SSC) models have been generally successful in interpreting the high-energy emission observed in other BL Lac objects, they are problematic for UHBLs, necessitating very large Doppler factors and/or extremely high minimum Lorentz factors of the emitting leptonic population. In this context, we have investigated alternative scenarios where hadronic emission processes are important, using a newly developed (lepto-)hadronic numerical code to systematically explore the physical parameters of the emission region that reproduces the observed spectra while avoiding the extreme values encountered in pure SSC models. Assuming a fixed Doppler factor $\delta=30$, two principal parameter regimes are identified, where the high-energy emission is due to: 1) proton-synchrotron radiation, with magnetic fields $B \sim 1-100\ \textrm{G}$ and maximum proton energies $E_{p;max} \lesssim 10^{19}$ eV; and 2) synchrotron emission from p-$\gamma$-induced cascades as well as SSC emission from primary leptons, with $B \sim 0.1-1\ \textrm{G}$ and $E_{p;max} \lesssim 10^{17}$ eV. This can be realized with plausible, sub-Eddington values for the total (kinetic plus magnetic) power of the emitting plasma, in contrast to hadronic interpretations for other blazar classes that often warrant highly super-Eddington values.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/00e117d50921b02c36739eeddf1e47db5be54f7b

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Citations in the corpus

Non-thermal particle acceleration in collisionless relativistic electron-proton reconnection (2016, background): “There are even a few ultrahigh-frequency-peaked BL Lacs (UHBLs) that demand γmax & 104, possibly requiring hadronic models (Cerruti et al. 2015).”
Modelling the coincident observation of a high-energy neutrino and a bright blazar flare (2018, unknown): “known that so-called proton synchrotron models may alleviate the tension with the Eddington limit (14), but they do not simultaneously reproduce the SED of TXS0506+056 and the energy and flux of neutrino emission, see Supplementary Figure 4; similar arguments apply to models with higher maximum prot”
The Blazar TXS 0506+056 Associated with a High-energy Neutrino: Insights into Extragalactic Jets and Cosmic-Ray Acceleration (2018, methodology): “The results presented here have been cross-checked with the codes developed in Cerruti et al. (2015) and Zech et al. (2017).”
Leptohadronic single-zone models for the electromagnetic and neutrino emission of TXS 0506+056 (2018, methodology): “We initially set η = 10 as in Cerruti et al. (2015).”
A Multimessenger Picture of the Flaring Blazar TXS 0506+056: Implications for High-energy Neutrino Emission and Cosmic-Ray Acceleration (2018, background): “There are different combinations of parameters that can successfully explain the SED in the HM scenario (Böttcher et al. 2013; Cerruti et al. 2015).”