Searching for Pseudo-Dirac neutrinos from Astrophysical sources in IceCube data

TL;DR

This study uses IceCube data to search for pseudo-Dirac neutrinos from astrophysical sources, constraining active-sterile neutrino oscillation parameters over a broad energy range with high confidence.

Contribution

It provides the first constraints on active-sterile neutrino mass-squared differences from astrophysical neutrino observations using IceCube data.

Findings

Excluded active-sterile mass-squared differences in the range [2.1×10⁻²¹, 2.0×10⁻¹⁶] eV² at ≥90% CL.

Extended the exclusion region down to 0.1 TeV energy range, broadening the constraints.

Performed stacking analysis of four sources to improve sensitivity.

Abstract

We analyze IceCube public data from its IC86 configuration, namely PSTracks event selection, to search for pseudo-Dirac signatures in high-energy neutrinos from astrophysical sources. Neutrino flux from astrophysical sources is reduced in the pseudo-Dirac scenario due to the conversion of active-to-sterile neutrinos as compared to the neutrino oscillation scenario of only three active neutrinos over astrophysical distances. We fit IceCube data using astrophysical flux models for four point-like sources in both scenarios and constrain the active-sterile mass-square-difference in the absence of any evidence for the pseudo-Dirac scenario. We present the exclusion regions for the common mass-squared difference $\delta m^2$, inducing active-sterile oscillations, for all three neutrino flavors. This includes results from individual sources as well as from a stacking analysis that combines data from the four sources. Our findings indicate that the exclusion region is $\delta m^2 \in [2.1\times 10^{-21} - 2.0\times 10^{-16}]$ eV$^2$ with $\ge 90\%$ confidence level (CL) significance for neutrino energies ranging from 0.5 TeV to 1 PeV. When we extend the energy range down to 0.1 TeV, the exclusion region broadens to $\delta m^2 \in [1.1 \times 10^{-21} - 3.0\times 10^{-16}]$ eV$^2$ at $\ge 90\%$ CL.