The IceCube Pie Chart: Relative Source Contributions to the Cosmic Neutrino Flux

TL;DR

This paper estimates the contributions of different astrophysical sources like AGNs, blazars, and TDEs to the cosmic neutrino flux detected by IceCube, revealing that blazars contribute minimally while AGNs or TDEs could dominate.

Contribution

It provides the first quantitative pie chart of source contributions to IceCube's neutrino flux based on current observational constraints.

Findings

Blazars contribute less than 11% of the total flux.

AGNs or TDEs could contribute over 50% of the flux.

Unknown sources may account for at least 10% of the flux.

Abstract

Neutrino events from IceCube have recently been associated with multiple astrophysical sources. Interestingly, these likely detections represent three distinct astrophysical source types: active galactic nuclei (AGN), blazars, and tidal disruption events (TDE). Here we compute the expected contributions of AGNs, blazars and TDEs to the overall cosmic neutrino flux detected by IceCube based on the associated events, IceCube's sensitivity, and the source types' astrophysical properties. We find that, despite being the most commonly identified sources, blazars cannot contribute more than 11% of the total flux (90% credible level), consistent with existing limits from stacked searches. On the other hand, we find that either AGNs or TDEs could contribute more than 50% of the total flux (90% credible level), although stacked searches further limit the TDE contribution to $\lesssim 30%$. We also find that so-far unknown source types contribute at least 10% of the total cosmic flux with a probability of 80%. We assemble a pie chart that shows the most likely fractional contribution of each source type to IceCube's total neutrino flux.