Search for neutrino emission in gamma-ray flaring blazars with the ANTARES telescope

TL;DR

This study searches for neutrino emissions from gamma-ray flaring blazars using ANTARES data, leveraging gamma-ray light curves to improve sensitivity and potentially identify astrophysical neutrino sources.

Contribution

The paper introduces a method that correlates neutrino detection with gamma-ray flares, enhancing sensitivity by focusing on periods of high activity in blazars.

Findings

Sensitivity improved by a factor of 2-3 over standard methods

Analysis of 2008 data with a likelihood ratio method

No significant neutrino detection, but promising future potential

Abstract

The ANTARES telescope observes a full hemisphere of the sky all the time with a duty cycle close to 100%. This makes it well suited for an extensive observation of neutrinos produced in astrophysical transient sources. In the surrounding medium of blazars, i.e. active galactic nuclei with their jets pointing almost directly towards the observer, neutrinos may be produced together with gamma-rays by hadronic interactions, so a strong correlation between neutrinos and gamma-rays emissions is expected. The time variability information of the studied source can be obtained by the gamma-ray light curves measured by the LAT instrument on-board the Fermi satellite. If the expected neutrino flux observation is reduced to a narrow window around the assumed neutrino production period, the point-source sensitivity can be drastically improved. The ANTARES data collected in 2008 has been analysed looking for neutrinos detected in the high state period of ten bright and variable Fermi sources assuming that the neutrino emission follows the gamma-ray light curves. First results show a sensitivity improvement by a factor 2-3 with respect to a standard time-integrated point source search. The analysis has been done with an unbinned method based on the minimization of a likelihood ratio applied to data corresponding to a live time of 60 days. The width of the flaring periods ranges from 1 to 20 days. Despite the fact that the most significant studied source is compatible with background fluctuations, recently detected flares promise interesting future analyse.