Are both BL Lacs and pulsar wind nebulae the astrophysical counterparts of IceCube neutrino events?

TL;DR

This study investigates potential astrophysical sources of IceCube high-energy neutrinos, identifying plausible counterparts mainly among BL Lacs and pulsar wind nebulae through gamma-ray catalog analysis and spectral comparison.

Contribution

It presents a systematic search for counterparts within gamma-ray catalogs and compares their spectral energy distributions with neutrino data, highlighting promising sources and challenges.

Findings

Likely counterparts include BL Lacs and pulsar wind nebulae.

Some sources are too weak to explain neutrino flux.

Further TeV observations and IceCube data are needed for confirmation.

Abstract

IceCube has recently reported the discovery of high-energy neutrinos of astrophysical origin, opening up the PeV (10^15 eV) sky. Because of their large positional uncertainties, these events have not yet been associated to any astrophysical source. We have found plausible astronomical counterparts in the GeV -- TeV bands by looking for sources in the available large area high-energy gamma-ray catalogues within the error circles of the IceCube events. We then built the spectral energy distribution of these sources and compared it with the energy and flux of the corresponding neutrino. Likely counterparts include mostly BL Lacs and two Galactic pulsar wind nebulae. On the one hand many objects, including the starburst galaxy NGC 253 and Centaurus A, despite being spatially coincident with neutrino events, are too weak to be reconciled with the neutrino flux. On the other hand, various GeV powerful objects cannot be assessed as possible counterparts due to their lack of TeV data. The definitive association between high-energy astrophysical neutrinos and our candidates will be significantly helped by new TeV observations but will be confirmed or disproved only by further IceCube data. Either way, this will have momentous implications for blazar jets, high-energy astrophysics, and cosmic-ray and neutrino astronomy.