A Search for Millimeter-Bright Blazars as Astrophysical Neutrino Sources

TL;DR

This study investigates the correlation between millimeter-wavelength blazar activity and high-energy neutrino emission, finding no significant overall correlation but identifying a notable individual source, TXS 0506+056.

Contribution

It provides the first catalog-based time-dependent analysis linking mm blazar emission with neutrino events, exploring both population and individual sources.

Findings

No significant stacked population signal detected.

TXS 0506+056 is the most significant individual source.

Most mm-bright blazars are neutrino dim.

Abstract

The powerful jets of blazars have been historically considered as likely sites of high-energy cosmic-ray acceleration. However, particulars of the launched jet and the locations of leptonic and hadronic jet loading remain unclear. In the case when leptonic and hadronic particle injection occur jointly, a temporal correlation between synchrotron radiation and neutrino production is expected. We use a first catalog of millimeter (mm) wavelength blazar light curves from the Atacama Cosmology Telescope for a time-dependent correlation with twelve years of muon neutrino events from the IceCube South Pole Neutrino Observatory. Such mm emission is known to trace activity of the bright jet base, which is often self-absorbed at lower frequencies and potentially gamma-ray opaque. We perform an analysis of the population, as well as analyses of individual, selected sources. We do not observe a significant signal from the stacked population. TXS 0506+056 is found as the most significant, individual source, though this detection is not globally significant in our analysis of selected AGN. Our results suggest that the majority of mm-bright blazars are neutrino dim. In general, it is possible that many blazars have lighter, leptonic jets, or that only selected blazars provide exceptional conditions for neutrino production.