ANTARES search for point-sources of neutrinos using astrophysical catalogs: a likelihood stacking analysis

TL;DR

This study used a likelihood stacking method on ANTARES data from 2007 to 2017 to search for neutrino point sources across various astrophysical catalogs, finding no significant associations but highlighting a potential signal from radio galaxies and a coincident blazar flare.

Contribution

The paper introduces a comprehensive likelihood stacking analysis of ANTARES data targeting multiple astrophysical source catalogs, including a joint analysis with IceCube data, to identify potential neutrino sources.

Findings

No significant neutrino source detection overall.

A 2.8 sigma pre-trial excess for radio galaxies.

A 2.0 sigma post-trial significance for a blazar with coincident flaring activity.

Abstract

A search for astrophysical point-like neutrino sources using the data collected by the ANTARES detector between January 29, 2007 and December 31, 2017 is presented. A likelihood stacking method is used to assess the significance of an excess of muon neutrinos inducing track-like events in correlation with the location of a list of possible sources. Different sets of objects are tested in the analysis: a) a sub-sample of the \textit{Fermi} 3LAC catalog of blazars, b) a jet-obscured AGN population, c) a sample of soft gamma-ray selected radio galaxies, d) a star-forming galaxy catalog , and e) a public sample of 56 very-high-energy track events from the IceCube experiment. None of the tested sources shows a significant association with the sample of neutrinos detected by ANTARES. The smallest p-value is obtained for the radio galaxies catalog with an equal weights hypothesis, with a pre-trial p-value equivalent to a $2.8 \, \sigma$ excess, equivalent to $1.6 \, \sigma$ post-trial. In addition, the results of a dedicated analysis for the blazar MG3 J225517+2409 are also reported: this source is found to be the most significant within the \textit{Fermi} 3LAC sample, with 5 ANTARES events located at less than one degree from the source. This blazar showed evidence of flaring activity in \textit{Fermi} data, in space-time coincidence with a high-energy track detected by IceCube. An \emph{a posteriori} significance of $2.0\, \sigma$ for the combination of ANTARES and IceCube data is reported.