Search for neutrino signals correlated with LHAASO diffuse Galactic emission

TL;DR

This study searches for neutrino signals correlated with diffuse Galactic gamma-ray emission observed by LHAASO, using IceCube data, and finds a mild excess consistent with hadronic interaction models.

Contribution

It is the first to perform a template and scan search for neutrinos correlated with LHAASO gamma-ray data in the Galactic plane.

Findings

A mild neutrino excess with 1.9σ pretrial significance in the Galactic plane.

Measured muon neutrino flux at 25 TeV aligns with hadronic interaction expectations.

Most significant scan location has 4.6σ pretrial significance, reduced to 1.8σ after trials.

Abstract

The diffuse Galactic $\gamma$-ray emission originates from the interactions between cosmic rays and the interstellar medium or radiation fields within our Galaxy, where the production of neutrinos is also anticipated. Recently, the Large High Altitude Air Shower Observatory (LHAASO) reported measurements of diffuse $\gamma$-rays from the Galactic plane with energies ranging from sub-TeV to 1 PeV. Using publicly available 7 years of IceCube track data with the full detector, we conduct a template search using the $\gamma$-ray flux map observed by LHAASO-KM2A as the neutrino emission template and perform a scan search of the Galactic plane. In the template search, a mild excess of neutrinos is observed in the Galactic plane with a pretrial (posttrial) significance of $1.9\sigma$ ($1.1\sigma$). The measured muon neutrino intensity at 25 TeV is $4.73^{+2.53}_{-2.51}\times10^{-14}\,{\rm TeV^{-1}\,cm^{-2}\,s^{-1}\,sr^{-1}}$, consistent with the expected neutrino flux assuming that all the diffuse Galactic $\gamma$-rays originate from hadronic interactions. In the Galactic plane scan search, the most significant location is found at $l=63.57^{\circ}$ and $b=0.93^{\circ}$ with a pretrial (posttrial) significance of $4.6\sigma$ ($1.8\sigma$).