Neutrinos from Starburst-Galaxies - A source stacking analysis of AMANDA II and IceCube data

Abstract

A stacking analysis performed with data from the IceCube neutrino observatory is presented in this paper. In general, the stacking technique is sensitive to a cumulative signal from a generic source class. This can lead to a significant signal for the most luminous sources of the class, even if the individual sources cannot be detected. Here, the final data set of the AMANDA-II experiment, which is the predecessor of the IceCube, is used for an analysis. In a second analysis, data from a quarter of the IceCube detector is used. IceCube consists of so called stings, these are steel cables with photo multipliers hooked up which are deployed into the Antarctic ice to depths between 1450 m and 2450 m. This analysis covers data taken with 22 strings of IceCube (IC-22) within one year. For the first time, a sample of Starburst Galaxies was analyzed. In addition, several AGN catalogs are used as well as a catalog of pulsars. The analysis did not reveal a significant neutrino signal for any of the analyzed source classes, neutrino flux limits were improved. The strongest limit was received for the class of Gigahertz Peaked / Compact Steep Spectrum sources (GPS/CSS), E2vdNv/dE vGPS<8.2.10-12GeV/s/sr per source, assuming an E-2v-shaped spectrum. This corresponds to an improvement of a factor of 2.5 compared with the average point source limit for single sources. © Author(s) 2011.