Search for point-like sources in the astrophysical muon neutrino flux with IceCube

Abstract

The IceCube Collaboration has observed a high-energy diffuse astrophysical neutrino flux consistently in two detection channels: first using high-energy events interacting inside the detector and secondly with through-going muon-neutrino induced muons. In order to identify the sources of this flux, these muon-neutrino events are ideal messenger particles because of their excellent angular resolution. Here we present a search for point-like neutrino sources based on the same sample that was used to measure the diffuse high-energy astrophysical muon-neutrino flux with a live-time of six years. This high purity sample is restricted to the Northern hemisphere and consists of $\sim340\,000$ events with a median angular resolution of $\sim1^\circ$ at 1 TeV that decreases to $\sim0.3^\circ$ at 1 PeV. In this analysis an unbinned likelihood maximization is used that is optimized for point-like neutrino emission with the same characteristics as the diffuse muon neutrino flux. The sensitivity improves by $\sim20\%$ compared to previous analyses and is at a level of $E^2 \partial \phi /\partial E = 4\cdot 10^{-13}\,\mathrm{TeV}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$. No significant source was found in an unbiased sky scan on the Northern hemisphere and in a search based on a standard candidate source list of IceCube and ANTARES.