BLAZARS AS ULTRA-HIGH-ENERGY COSMIC-RAY SOURCES: IMPLICATIONS FOR TeV GAMMA-RAY OBSERVATIONS
By Kohta Murase, C. Dermer, H. Takami, G. Migliori. 2011
181 citations recorded by the source corpus.
The spectra of BL Lac objects and Fanaroff–Riley I radio galaxies are commonly explained by the one-zone leptonic synchrotron self-Compton (SSC) model. Spectral modeling of correlated multiwavelength data gives the comoving magnetic field strength, the bulk outflow Lorentz factor, and the emission region size. Assuming the validity of the SSC model, the Hillas condition shows that only in rare cases such sources accelerate protons to much above 1019 eV, so ≳ 1020 eV ultra-high-energy cosmic rays (UHECRs) are likely to be heavy ions if powered by this type of radio-loud active galactic nuclei (AGNs). Survival of nuclei is shown to be possible in TeV BL Lacs and misaligned counterparts with weak photohadronic emissions. Another signature of hadronic production is intergalactic UHECR-induced cascade emission, which is an alternative explanation of the TeV spectra of some extreme non-variable blazars such as 1ES 0229+200 or 1ES 1101−232. We study this kind of cascade signal, taking into account effects of the structured extragalactic magnetic fields in which the sources should be embedded. We demonstrate the importance of cosmic-ray deflections on the γ-ray flux, and show that required absolute cosmic-ray luminosities are larger than the average UHECR luminosity inferred from UHECR observations and can even be comparable to the Eddington luminosity of supermassive black holes. Future TeV γ-ray observations using the Cerenkov Telescope Array and the High Altitude Water Cerenkov detector array can test for UHECR acceleration by observing >25 TeV photons from relatively low redshift sources such as 1ES 0229+200, and ≳TeV photons from more distant radio-loud AGNs.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/3f1620ac8aa17396db1ed74f3b371f51bd7853a3
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Citations in the corpus
- Blazar Flares as an Origin of High-energy Cosmic Neutrinos? (2018, background): “With a typical jet luminosity of BL Lacs, it is difficult for a massive cloud to become highly relativistic.”
- Indications for a pair-production anomaly from the propagation of VHE gamma-rays (2012, background): “[3, 4] for gamma-ray induced cascades and [5–7] for ultra-high energy proton induced cascades)1.”
- Open Questions in Cosmic-Ray Research at Ultrahigh Energies (2019, unknown): “For a given source density, a CR energy can be found for which the distance between sources matches the cosmic-ray scattering length in the turbulent medium it is propagating through (Kotera and Lemoine, 2008b; Takami and Murase, 2012).”
- A hadronic origin for ultra-high-frequency-peaked BL Lac objects (2014, background): “The above mentioned intergalactic cascades may also provide a hard spectral component at the highest energies to fit the spectra of UHBLs, as was shown for example for 1ES 0229+200 by Murase et al. (2012).”