Search for a diffuse flux of high-energy $\nu_\mu$ with the ANTARES neutrino telescope

TL;DR

This paper reports a search for high-energy astrophysical muon neutrinos using the ANTARES telescope, setting upper limits on their diffuse flux and testing various spectral models.

Contribution

First to set upper limits on diffuse high-energy muon neutrino flux with ANTARES data over 334 days and evaluate different spectral models.

Findings

No excess over atmospheric background observed

Established a 90% confidence level upper limit on neutrino flux

Rejected some spectral models based on data

Abstract

A search for a diffuse flux of astrophysical muon neutrinos, using data collected by the ANTARES neutrino telescope is presented. A $(0.83\times 2\pi)$ sr sky was monitored for a total of 334 days of equivalent live time. The searched signal corresponds to an excess of events, produced by astrophysical sources, over the expected atmospheric neutrino background. The observed number of events is found compatible with the background expectation. Assuming an $E^{-2}$ flux spectrum, a 90% c.l. upper limit on the diffuse $\nu_\mu$ flux of $E^2\Phi_{90%} = 5.3 \times 10^{-8} \ \mathrm{GeV\ cm^{-2}\ s^{-1}\ sr^{-1}} $ in the energy range 20 TeV - 2.5 PeV is obtained. Other signal models with different energy spectra are also tested and some rejected.