Assessing coincident neutrino detections using population models
Abstract
Several tentative associations between highenergy neutrinos and astrophysical sources have been recently reported, but a conclusive identification of these potential neutrino emitters remains challenging. We explore the use of Monte Carlo simulations of source populations to gain deeper insight into the physical implications of proposed individual sourceneutrino associations. In particular, we focus on the IC170922ATXS 0506+056 observation. Assuming a null model, we find a 7.6% chance of mistakenly identifying coincidences between γray flares from blazars and neutrino alerts in 10year surveys. We confirm that a blazarneutrino connection based on the γray flux is required to find a low chance coincidence probability and, therefore, a significant IC170922ATXS 0506+056 association. We then assume this blazarneutrino connection for the whole population and find that the ratio of neutrino to γray fluxes must be ≲10^{−2} in order not to overproduce the total number of neutrino alerts seen by IceCube. For the IC170922ATXS 0506+056 association to make sense, we must either accept this low flux ratio or suppose that only some rare subpopulation of blazars is capable of highenergy neutrino production. For example, if we consider neutrino production only in blazar flares, we expect the flux ratio of between 10^{−3} and 10^{−1} to be consistent with a single coincident observation of a neutrino alert and flaring γray blazar. These constraints should be interpreted in the context of the likelihood models used to find the IC170922ATXS 0506+056 association, which assumes a fixed powerlaw neutrino spectrum of E^{−2.13} for all blazars.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 December 2022
 DOI:
 10.1051/00046361/202243116
 arXiv:
 arXiv:2201.05633
 Bibcode:
 2022A&A...668A.190C
 Keywords:

 neutrinos;
 astroparticle physics;
 methods: data analysis;
 Astrophysics  High Energy Astrophysical Phenomena;
 Astrophysics  Instrumentation and Methods for Astrophysics
 EPrint:
 Accepted version