Low-energy point source searches with IceCube

Sebastian Euler,Rickard Ström,David Altmann

doi:10.1051/epjconf/201611604004

Abstract

Due to the overwhelming background of atmospheric muons, the traditional IceCube point source search in the Southern Hemisphere is mainly sensitive to neutrinos with energies above 100TeV. A new approach focuses on events starting inside the instrumented volume. By utilizing different veto techniques we are able to significantly reduce the energy threshold and can now for the first time explore the entire Southern Hemisphere at neutrino energies as low as 100GeV. We present the results of two analyses targeting slightly different energy ranges. Both use one year of data taken with the completed IceCube detector in 2011/12.

Highlights

Due to the overwhelming background of atmospheric muons, the traditional IceCube point source search in the Southern Hemisphere is mainly sensitive to neutrinos with energies above 100TeV
By utilizing different veto techniques we are able to significantly reduce the energy threshold and can for the first time explore the entire Southern Hemisphere at neutrino energies as low as 100GeV
The standard IceCube neutrino point source search [1] is most sensitive in the Northern Hemisphere, where the Earth shields the massive background from atmospheric muons

Summary

Introduction

The standard IceCube neutrino point source search [1] is most sensitive in the Northern Hemisphere, where the Earth shields the massive background from atmospheric muons. In the Southern Hemisphere, this analysis is limited to the highest energies above 100TeV, where the atmospheric background is sufficiently low. The Southern Hemisphere is, an interesting target, in particular at lower energies, as it contains the Galactic center and a large part of the inner Galaxy, with many potential neutrino sources [2, 3]. Events starting inside the IceCube detector [4] are an unambiguous signature of a neutrino interaction. By utilizing different veto techniques and focusing on starting events it is possible to reduce the background to a tolerable level and significantly lower the energy threshold for neutrino point source searches in the Southern Hemisphere. We present two such analyses, one aimed at an energy range of a few TeV to 100 TeV (STeVE – Starting TeV Events), and the other one aimed at even lower energies above 100GeV (LESE – Low Energy Starting Events)

Data samples

Analysis method

Results

Summary and outlook