On the detectability of BL Lac objects by IceCube

TL;DR

This paper evaluates the potential of IceCube to detect high-energy neutrinos from BL Lac objects, considering background noise and Earth absorption, and finds that detection is plausible but not guaranteed.

Contribution

It introduces a model linking gamma-ray and neutrino fluxes from HBL sources and assesses detection significance with current and upcoming neutrino observatories.

Findings

Detection significance depends on source flux and background levels.

Current data does not exclude the possibility of no detection.

The scenario aligns with existing non-detections.

Abstract

Since 2010 IceCube observed around 50 high-energy neutrino events of cosmic origin above 60 TeV, but the astrophysical sources of these events are still unknown. We recently proposed high-energy emitting BL Lac (HBL) objects as candidate emitters of high-energy neutrinos. Assuming a direct proportionality between high-energy gamma-ray and very-high energy neutrino fluxes, we calculated the expected neutrino event number in a year for IceCube and the presently under construction Km3NeT. To give a value of the significance of a detection we considered also the background for the single sources. To this aim we derived the through-going muon rate, generated by muon neutrino including the effect of Earth absorption, the density of the Earth and the cross section $\nu N$. Applying this calculation both to HBL sources and the atmospherical neutrino background, we can calculate the expected significance of the detection by IceCube, showing that our scenario is compatible with a no detection of HBL.