The physical properties of candidate neutrino-emitter blazars

¹ Julius-Maximilians-Universität Würzburg, Fakultät für Physik und Astronomie, Würzburg, Germany
² Deutsches Elektronen-Synchrotron DESY, Zeuthen, Germany
³ Université Paris Cité, CNRS, Astroparticule et Cosmologie, Paris, France

^* e-mail: alessandra.azzollini@uni-wuerzburg.de
^** now at Departament d’Astronomia i Astrofísica, Universitat de València, Burjassot, València, Spain

Published online: 6 March 2025

Abstract

High-energy neutrinos detected by the IceCube Observatory provide a unique opportunity to study the origin of cosmic rays and the nature of the sources producing them. Among the putative birthplaces of astrophysical highenergy neutrinos, blazar jets stand out due to their capability of accelerating particles and providing intense external radiation fields. Blazars are active galactic nuclei (AGN), a class of luminous extragalactic objects powered by a central supermassive black hole, with the jets pointing in the observer’s line of sight. In this contribution, we focus on a selected sample of 52 blazars that have been proposed as candidate IceCube neutrino counterparts (post-trial statistical significance 5σ). We use multiwavelength data, both archival and proprietary, in the radio, optical, and γ-ray bands and characterize the sources’ nature and their central engine’s peculiarities. Properties such as redshift, black hole mass, accretion regime, radiation field, and jet power are crucial to investigate the properties of these blazars and the potential link with the acceleration of cosmic rays. Our study shows that these 52 neutrino-emitter blazar candidates show a mild tendency toward radiatively efficient accretion and high jet power. However, statistical tests show they are compatible with the overall population of blazars.