Proton Synchrotron $gamma$-rays and the Energy Crisis in Blazars. (arXiv:2003.10460v1 [astro-ph.HE])

Proton Synchrotron $gamma$-rays and the Energy Crisis in Blazars. (arXiv:2003.10460v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Liodakis_I/0/1/0/all/0/1">I. Liodakis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Petropoulou_M/0/1/0/all/0/1">M. Petropoulou</a>

The origin of high-energy emission in blazars jets (i.e., leptonic versus
hadronic) has been a long-standing matter of debate. Here, we focus on one
variant of hadronic models where proton synchrotron radiation accounts for the
observed steady $gamma$-ray blazar emission. Using analytical methods, we
derive the minimum jet power ($P_{j,min}$) for the largest blazar sample
analyzed to date (145 sources), taking into account uncertainties of
observables and jet’s physical parameters. We compare $P_{j,min}$ against
three characteristic energy estimators for accreting systems, i.e., the
Eddington luminosity, the accretion disk luminosity, and the power of the
Blandford-Znajek process, and find that $P_{j,min}$ is about 2 orders of
magnitude higher than all energetic estimators for the majority of our sample.
The derived magnetic field strengths in the emission region require either
large amplification of the jet’s magnetic field (factor of 30) or place the
$gamma$-ray production site at sub-pc scales. The expected neutrino emission
peaks at $sim 0.1-10$ EeV, with typical peak neutrino fluxes $sim 10^{-4}$
times lower than the peak $gamma$-ray fluxes. We conclude that if relativistic
hadrons are present in blazar jets, they can only produce a radiatively
subdominant component of the overall spectral energy distribution of the
blazar’s steady emission.

The origin of high-energy emission in blazars jets (i.e., leptonic versus
hadronic) has been a long-standing matter of debate. Here, we focus on one
variant of hadronic models where proton synchrotron radiation accounts for the
observed steady $gamma$-ray blazar emission. Using analytical methods, we
derive the minimum jet power ($P_{j,min}$) for the largest blazar sample
analyzed to date (145 sources), taking into account uncertainties of
observables and jet’s physical parameters. We compare $P_{j,min}$ against
three characteristic energy estimators for accreting systems, i.e., the
Eddington luminosity, the accretion disk luminosity, and the power of the
Blandford-Znajek process, and find that $P_{j,min}$ is about 2 orders of
magnitude higher than all energetic estimators for the majority of our sample.
The derived magnetic field strengths in the emission region require either
large amplification of the jet’s magnetic field (factor of 30) or place the
$gamma$-ray production site at sub-pc scales. The expected neutrino emission
peaks at $sim 0.1-10$ EeV, with typical peak neutrino fluxes $sim 10^{-4}$
times lower than the peak $gamma$-ray fluxes. We conclude that if relativistic
hadrons are present in blazar jets, they can only produce a radiatively
subdominant component of the overall spectral energy distribution of the
blazar’s steady emission.

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