Multimessenger observations of counterparts to IceCube-190331A

TL;DR

This study investigates the potential astrophysical sources of the high-energy neutrino IceCube-190331A through multiwavelength observations, identifying promising counterparts but finding no definitive source, highlighting the challenges in neutrino source identification.

Contribution

The paper presents a comprehensive multiwavelength follow-up of IceCube-190331A, identifying potential counterparts and discussing the limitations in current neutrino source detection methods.

Findings

Identified two promising counterparts within the localization region.

No gamma-ray or prompt X-ray sources were associated with the neutrino event.

The Helix Nebula's position is consistent but unlikely to produce the neutrino energies.

Abstract

High-energy neutrinos are a promising tool for identifying astrophysical sources of high and ultra-high energy cosmic rays (UHECR). Prospects of detecting neutrinos at high energies ($\gtrsim$TeV) from blazars have been boosted after the recent association of IceCube-170922A and TXS 0506+056. We investigate the high-energy neutrino, IceCube-190331A, a high-energy starting event (HESE) with a high likelihood of being astrophysical in origin. We initiated a Swift/XRT and UVOT tiling mosaic of the neutrino localisation, and followed up with ATCA radio observations, compiling a multiwavelength SED for the most likely source of origin. NuSTAR observations of the neutrino location and a nearby X-ray source were also performed. We find two promising counterpart in the 90% confidence localisation region and identify the brightest as the most likely counterpart. However, no Fermi/LAT $\gamma$-ray source and no prompt Swift/BAT source is consistent with the neutrino event. At this point it is unclear whether any of the counterparts produced IceCube-190331A. We note that the Helix Nebula is also consistent with the position of the neutrino event, and we calculate that associated particle acceleration processes cannot produce the required energies to generate a high-energy HESE neutrino.