Search for high-energy neutrinos from Einstein Probe detected Fast X-ray Transients using 14 years of IceCube muon track data

Abstract

We perform a time-integrated search for high energy neutrinos from 27 fast X-ray transients (FXTs) detected by Einstein Probe, using 14 years of publicly available IceCube muon-track data. We employ the unbinned maximum likelihood method which is used for IceCube point source searches. We do not find any statistically significant excess from any of the FXTs. The largest TS value is obtained for EP240801a (TS=4.77), corresponding to a local $p$-value of 0.04, which is not significant. We therefore calculate 90\% confidence level upper limit on the differential muon neutrino flux. The most stringent upper limit is obtained for EP241021a, with $E^2 \Phi(E)=2.1\times 10^{-10}$ (GeV cm$^{-2}$ s$^{-1}$), for a $E^{-2}$ spectrum at a pivot energy of 100 TeV.