Diffuse neutrino flux measurements with the Baikal-GVD neutrino telescope

TL;DR

This paper reports the first detection of diffuse cosmic neutrino flux with Baikal-GVD, observing a significant excess of cascade events consistent with IceCube's findings, and provides best-fit spectral parameters.

Contribution

First observation of diffuse cosmic neutrino flux with Baikal-GVD, confirming its capability to detect high-energy astrophysical neutrinos.

Findings

Significant excess of cascade events over atmospheric background.

Flux parameters consistent with IceCube measurements.

Rejection of null cosmic flux hypothesis at 3.05σ significance.

Abstract

We report on the first observation of the diffuse cosmic neutrino flux with the Baikal-GVD neutrino telescope. Using cascade-like events collected by Baikal-GVD in 2018--2021, a significant excess of events over the expected atmospheric background is observed. This excess is consistent with the high-energy diffuse cosmic neutrino flux observed by IceCube. The null cosmic flux assumption is rejected with a significance of 3.05$\sigma$. Assuming a single power law model of the astrophysical neutrino flux with identical contribution from each neutrino flavor, the following best-fit parameter values are found: the spectral index $\gamma_{astro}$ = $2.58^{+0.27}_{-0.33}$ and the flux normalization $\phi_{astro}$ = 3.04$^{+1.52}_{-1.21}$ per one flavor at 100 TeV.