The physical properties of candidate neutrino-emitter blazars

TL;DR

This study characterizes 52 candidate neutrino-emitting blazars by analyzing their optical, radio, and gamma-ray properties to understand their potential role in high-energy neutrino production, highlighting the importance of accretion regimes and jet power.

Contribution

It provides the first detailed physical characterization of candidate neutrino-emitting blazars, linking their properties to potential neutrino production mechanisms.

Findings

Candidate blazars show properties compatible with known blazar populations.

A mild preference for radiatively efficient accretors with intense radiation fields.

Statistical tests are sensitive to sample size and censored data, requiring careful application.

Abstract

The processes governing the production of astrophysical high-energy neutrinos are still debated, and the sources originating them remain an open question. Among the putative emitters, active galactic nuclei have gained increasing attention. Blazars, in particular, stand out due to their ability to accelerate particles in environments with external radiation fields. Recent observations suggest they may contribute to the neutrino flux detected by IceCube. We study the physical properties of a subsample of 52 blazars proposed as candidate neutrino emitters, based on a positional cross-correlation analysis between IceCube hotspots and the 5BZCat catalog. We aim to provide a first characterization of their central engines and physical nature, to explore the potential link with neutrino production. We analyze the optical spectroscopic properties of the 52 candidate neutrino-emitter blazars to infer their accretion regime. The study is complemented by radio and $\gamma$-ray data, which trace the intrinsic jet power. We compare the sample to other blazar populations in the literature, perform statistical tests, and explore, through simulations, the applicability of methods that include censored data. Overall, the target sample shows properties compatible with the reference samples. We observe a mild tendency to prefer objects with intense radiation fields, typical of radiatively efficient accretors, and high radio power. Among them, 24 are detected by Fermi-LAT, spanning various $\gamma$-ray luminosities. We also show that statistical tests commonly used in the literature need to be handled with caution, as they are sensitive to the number of censored data and the sample size.