Neutrinos, Cosmic Rays and the MeV Band. (arXiv:1903.05765v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ojha_R/0/1/0/all/0/1">R. Ojha</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_H/0/1/0/all/0/1">H. Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kadler_M/0/1/0/all/0/1">M. Kadler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Neilson_N/0/1/0/all/0/1">N. K. Neilson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kreter_M/0/1/0/all/0/1">M. Kreter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McEnery_J/0/1/0/all/0/1">J. McEnery</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Buson_S/0/1/0/all/0/1">S. Buson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Caputo_R/0/1/0/all/0/1">R. Caputo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Coppi_P/0/1/0/all/0/1">P. Coppi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+DAmmando_F/0/1/0/all/0/1">F. D&#x27;Ammando</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Angelis_A/0/1/0/all/0/1">A. De Angelis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fang_K/0/1/0/all/0/1">K. Fang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Giannios_D/0/1/0/all/0/1">D. Giannios</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guiriec_S/0/1/0/all/0/1">S. Guiriec</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guo_F/0/1/0/all/0/1">F. Guo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kopp_J/0/1/0/all/0/1">J. Kopp</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Krauss_F/0/1/0/all/0/1">F. Krauss</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_H/0/1/0/all/0/1">H. Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meyer_M/0/1/0/all/0/1">M. Meyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moiseev_A/0/1/0/all/0/1">A. Moiseev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Petropoulou_M/0/1/0/all/0/1">M. Petropoulou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prescod_Weinstein_C/0/1/0/all/0/1">C. Prescod-Weinstein</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rani_B/0/1/0/all/0/1">B. Rani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shrader_C/0/1/0/all/0/1">C. Shrader</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Venters_T/0/1/0/all/0/1">T. Venters</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wadiasingh_Z/0/1/0/all/0/1">Z. Wadiasingh</a>

The possible association of the blazar TXS 0506+056 with a high-energy
neutrino detected by IceCube holds the tantalizing potential to answer three
astrophysical questions: 1. Where do high-energy neutrinos originate? 2. Where
are cosmic rays produced and accelerated? 3. What radiation mechanisms produce
the high-energy {gamma}-rays in blazars? The MeV gamma-ray band holds the key
to these questions, because it is an excellent proxy for photo-hadronic
processes in blazar jets, which also produce neutrino counterparts. Variability
in MeV gamma-rays sheds light on the physical conditions and mechanisms that
take place in the particle acceleration sites in blazar jets. In addition,
hadronic blazar models also predict a high level of polarization fraction in
the MeV band, which can unambiguously distinguish the radiation mechanism.
Future MeV missions with a large field of view, high sensitivity, and
polarization capabilities will play a central role in multi-messenger
astronomy, since pointed, high-resolution telescopes will follow neutrino
alerts only when triggered by an all-sky instrument.

The possible association of the blazar TXS 0506+056 with a high-energy
neutrino detected by IceCube holds the tantalizing potential to answer three
astrophysical questions: 1. Where do high-energy neutrinos originate? 2. Where
are cosmic rays produced and accelerated? 3. What radiation mechanisms produce
the high-energy {gamma}-rays in blazars? The MeV gamma-ray band holds the key
to these questions, because it is an excellent proxy for photo-hadronic
processes in blazar jets, which also produce neutrino counterparts. Variability
in MeV gamma-rays sheds light on the physical conditions and mechanisms that
take place in the particle acceleration sites in blazar jets. In addition,
hadronic blazar models also predict a high level of polarization fraction in
the MeV band, which can unambiguously distinguish the radiation mechanism.
Future MeV missions with a large field of view, high sensitivity, and
polarization capabilities will play a central role in multi-messenger
astronomy, since pointed, high-resolution telescopes will follow neutrino
alerts only when triggered by an all-sky instrument.

http://arxiv.org/icons/sfx.gif