Analysis of the cumulative neutrino flux from Fermi-LAT blazar populations using 3 years of IceCube data

TL;DR

This study searched for cumulative neutrino emissions from Fermi-LAT identified blazar populations using three years of IceCube data, finding no significant signals but discussing implications for the origin of diffuse PeV neutrinos.

Contribution

It introduces a comprehensive likelihood analysis of large blazar populations with IceCube data, extending previous searches to include hundreds of sources.

Findings

No significant neutrino emission detected from blazar populations.

Results constrain the contribution of blazars to the diffuse PeV neutrino flux.

Implications suggest other sources may dominate the diffuse neutrino background.

Abstract

The recent discovery of a diffuse neutrino flux up to PeV energies raises the question of which populations of astrophysical sources contribute to this diffuse signal. One extragalactic candidate source population to produce high-energy neutrinos are Blazars. We present results from a likelihood analysis searching for cumulative neutrino emission from Blazar populations selected with the 2nd Fermi-LAT AGN catalog (2LAC) using an IceCube data set that has been optimized for the detection of individual sources. In contrast to previous searches with IceCube, the investigated populations contain up to hundreds of sources, the biggest one being the entire Blazar sample measured by the Fermi-LAT. No significant neutrino signal was found from any of these populations. Some implications of this non-observation for the origin of the observed PeV diffuse signal will be discussed.