First constraints on point-like astrophysical sources using Baikal-GVD muon neutrino events

Abstract

Baikal-GVD is a new-generation neutrino telescope under final construction stages in Lake Baikal, Russia. With an instrumented volume already at 0.7 km${}^3$, Baikal-GVD is currently the largest neutrino telescope in the Northern hemisphere. A sub-degree angular resolution, made possible thanks to high purity of Baikal water, further enhances Baikal-GVD sensitivity to cosmic neutrino sources. In this work, we employ track-like events collected from the partially completed detector between April 2019 and March 2024 to search for muon neutrino fluxes from 92 astrophysical objects of interest. For this, a $\ddot{I}{‡}^2$-based track reconstruction method is used along with a cut-based analysis. The analysis uses upward-going muons only, providing coverage for declinations between -90${}^{\circ }$ and +38${}^{\circ }$. No significant excess has been found, so upper limits are reported. The obtained limits are competitive with those set by ANTARES and KM3NeT. We briefly comment on a possible low-significance indication of an excess from the direction of Westerlund 1. This work sets a major milestone on the way to full-scale scientific exploitation of Baikal-GVD data.

16 pages, 3 figures, 1 table. To appear in Astronomy Letters