arXiv subjects

V. Y. Shishkin

Publications and source records attributed to V. Y. Shishkin.

5 recordsLinked to original sources

arXiv2026

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

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 $χ^2$-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.

astro-ph.HE↗

arXiv2025

Design and Implementation of the Fast Data Processing System for the Baikal-GVD Neutrino Telescope

We present a fast data processing system for the Baikal-GVD neutrino telescope, designed for rapid identification of astrophysical neutrino events. Leveraging Baikal-GVD's modular cluster architecture, the system implements parallelized file processing where raw data files undergo concurrent analysis across dedicated virtual machines. The system implements two pipelines: a fast per-file processing and a fully fledged (per-run) processing, which integrates dynamic detector geometry determined from acoustic and inertial positioning systems and data quality monitoring with a latency of about 27 hr. The fast processing pipeline delivers a total latency of about 1.5-18 minutes from event detection to reconstructed data availability, depending on water luminescence levels. This enables fast follow-up observations of transient astrophysical sources, fulfilling Baikal-GVD's role in multi-messenger networks. The article also highlights key features of the data acquisition system, the integration of advanced synchronization systems and a robust infrastructure for data handling and storage, ensuring efficient and reliable operation of the Baikal-GVD telescope.

astro-ph.IM↗

arXiv2025

Constraints on the diffuse flux of multi-PeV astrophysical neutrinos obtained with the Baikal Gigaton Volume Detector

Various theoretical models predict cosmic neutrinos with multi-PeV energies. The recent detection of a ~10^17 eV neutrino in the KM3NeT experiment suggests that these energetic particles can be studied with present-day installations. Here, we present upper limits on the flux of astrophysical neutrinos with energies (10^15.5 - 10^20) eV obtained with the largest liquid-water neutrino telescope, Baikal Gigaton Volume Detector (GVD), operation using cascade-like events. We discuss astrophysical implications of these results and constrain several cosmogenic neutrino scenarios using a combination of Baikal-GVD, KM3NeT, IceCube and Auger data.

astro-ph.HE↗

arXiv2025

Measurement of the diffuse astrophysical neutrino flux over six seasons using cascade events from the Baikal-GVD expanding telescope

We present an updated measurement of the diffuse astrophysical neutrino flux using Baikal-GVD cascade data collected between April 2018 to March 2024. In this period, the detector grew from 15% to 55% of its baseline cubic kilometer configuration. The diffuse astrophysical neutrino flux is detected with a statistical significance of 5.1 $σ$. 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 $γ_{astro}$ = 2.64$^{+0.09}_{-0.11}$ and the flux normalization $ϕ_{astro}$ = 4.42$^{+2.31}_{-1.29}\times10^{-18} \text{GeV}^{-1}\text{cm}^{-2}\text{s}^{-1}\text{sr}^{-1}$ per one flavor at 100 TeV. These results are broadly consistent with IceCube measurements.

astro-ph.HE↗

arXiv2025

Probing the Galactic neutrino flux at neutrino energies above 200 TeV with the Baikal Gigaton Volume Detector

Recent observations of the Galactic component of the high-energy neutrino flux, together with the detection of the diffuse Galactic gamma-ray emission up to sub-PeV energies, open new possibilities to study the acceleration and propagation of cosmic rays in the Milky Way. At the same time, both large non-astrophysical backgrounds at TeV energies and scarcity of neutrino events in the sub-PeV band currently limit these analyses. Here we use the sample of cascade events with estimated neutrino energies above 200 TeV, detected by the partially deployed Baikal Gigaton Volume Detector (GVD) in six years of operation, to test the continuation of the Galactic neutrino spectrum to sub-PeV energies. We find that the distribution of the arrival directions of Baikal-GVD cascades above 200 TeV in the sky suggests an excess of neutrinos from low Galactic latitudes with the chance probability of 1.4e-2. We find the excess above 200 TeV also in the most recent IceCube public data sets, both of cascades and tracks. The chance probability of the excess in the combined IceCube and Baikal-GVD analysis is 3.4e-4. The flux of Galactic neutrinos above 200~TeV challenges often-used templates for neutrino search based on cosmic-ray simulations.

astro-ph.HE↗