Search for muon neutrinos from GRBs with the ANTARES neutrino telescope

ANTARES is the largest operational neutrino telescope in the Northern hemisphere, located in the deep water of the Mediterranean Sea, offshore Toulon. One of its main scientific goals concerns the identification of hadronic astrophysical accelerators through the detection of high-energy neutrinos. Among these sources, Gamma-Ray Bursts (GRBs) constitutes promising candidates because they are the most bright sources in the Universe. Their transient nature allows to drastically reduce the expected background when both a temporal and spatial correlation with the observed gamma-ray prompt emission is required. Cosmic neutrinos could be produced in the interaction between accelerated protons and intense radiation fields in the jet. Two different approaches have been adopted in the search: a stacked analysis with a sample of GRBs observable using the full ANTARES data set (from 2008 to 2016) and an individual search from some of the brightest GRBs (with gamma-ray fluence greater than 10-4 erg/cm2) occurred in the same time period. The methods and the results of these searches for muon neutrinos are here presented. The stacking analysis allows to constrain the contribution to the diffuse flux of neutrinos from this population of sources. In the bright GRB analysis, instead, the internal shock and the photospheric scenarios have been investigated and limits in the parameter space of the fireball model are derived individually. Since no events have been detected in spatial and temporal coincidence with GRBs in any of the searches, upper limits on neutrino fluence are derived both for individual bright sources and for the GRB population sample.