Measurement of the diffuse astrophysical neutrino flux over six seasons using cascade events from the Baikal-GVD expanding telescope
astro-ph.HE
/ Authors
Baikal-GVD Collaboration, :, V. A. Allakhverdyan, A. D. Avrorin, A. V. Avrorin, V. M. Aynutdinov, Z. Beňušová, I. A. Belolaptikov, E. A. Bondarev, I. V. Borina
and 61 more authors
N. M. Budnev, V. A. Chadymov, A. S. Chepurnov, V. Y. Dik, A. N. Dmitrieva, G. V. Domogatsky, A. A. Doroshenko, R. Dvornický, A. N. Dyachok, Zh. -A. M. Dzhilkibaev, E. Eckerová, T. V. Elzhov, V. N. Fomin, A. R. Gafarov, K. V. Golubkov, T. I. Gress, K. G. Kebkal, V. K. Kebkal, I. V. Kharuk, S. S. Khokhlov, E. V. Khramov, M. M. Kolbin, S. O. Koligaev
/ Abstract
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.