ANTARES and IceCube joint search opens a new dimension in Neutrino Astronomy

The ANTARES and IceCube neutrino telescopes were built with a common objective: the search for sources of astrophysical neutrinos. Although both collaborations usually present their analysis individually, last Friday the results of the first combined analysis with data from both detectors were sent to the Astrophysical Journal. This combined analysis searches for cosmic neutrino point-sources over the whole Southern Sky. Although no excess has been observed, it has been shown that the combination of both data samples improves the sensitivity for point-sources up to a factor 2. The actual amount of improvement and its location in declination depends on the assumed energy spectrum of the source.

90% CL limits and sensitivities for E-2.5 point-sources coming from the Southern Sky using the combined analysis (green) compared to the individual ANTARES (blue) and IceCube (red) detectors.
90% CL limits and sensitivities for E-2 point-sources coming from the Southern Sky using the combined analysis (green) compared to the individual ANTARES (blue) and IceCube (red) detectors. It can be seen that the region with the largest improvement precisely corresponds to the Galactic Centre area.

The reason for this complementarity is due to a combination of the different locations and sizes of both detectors. IceCube is located in the Antarctic ice, whereas ANTARES was deployed in the Mediterranean Sea. In order to observe the Southern Sky, ANTARES can use the Earth as a filter against the huge background of atmospheric muons, which gives a better sensitivity for neutrino energies up to 100 TeV, particularly important for Galactic sources. On the other hand, IceCube, given its larger size, presents a better sensitivity beyond this energy, where the background of atmospheric muons is smaller.

In this analysis, the 2007-2012 data sample from the last ANTARES published point-source search and the 2007-2011 point-source data sample from IceCube have been used. The most significant cluster from the full Southern Sky search was found at equatorial coordinates α=332.8° and δ=-46.1, with a post-trial significance of 0.7sigma. A search over 40 pre-selected sources was also performed, with a post-trial significance of 1.2sigma for the most significant candidate source (HESSJ1741-302).

This is the first analysis which combines the data and the effort from both collaborations. Further analysis combining data from both detectors are planned in order to provide the best sensitivies for Galactic sources in the Southern Sky.

“First combined search for neutrino point-sources in the Southern Hemisphere with the ANTARES and IceCube neutrino telescopes”, ANTARES and IceCube Collaborations: S. Adrián-Martínez et al. Submitted to Astrophysical Journal,