Upper Limit on the Diffuse Flux of Cosmic $\nu_\mu$ with the ANTARES Neutrino Telescope

TL;DR

This paper reports a search for diffuse astrophysical muon neutrino flux using ANTARES data from 2007-2009, setting an upper limit on the flux in the 20 TeV to 2.5 PeV range, with no significant excess detected.

Contribution

First to set an upper limit on the diffuse muon neutrino flux with ANTARES over this energy range using 2007-2009 data.

Findings

No significant excess of neutrinos over background was observed.

An upper limit on the diffuse muon neutrino flux was established at $E^2\Phi_{90"} = 5.3 imes 10^{-8} ext{GeV cm}^{-2} s^{-1} sr^{-1}.

Some alternative signal models with different energy spectra were tested and rejected.

Abstract

A search for a diffuse flux of astrophysical muon neutrinos, using data collected by the ANTARES neutrino telescope from December 2007 to December 2009 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 without any particular assumption on the source direction. Since the number of detected events is compatible with the number of expected background events, a 90% c.l. upper limit on the diffuse $\nu_\mu$ flux with a $E^{-2}$ spectrum is set at $E^2\Phi_{90%} = 5.3 \times 10^{-8} \ \mathrm{GeV\ cm^{-2}\ s^{-1}\ sr^{-1}}$ in the energy range 20 TeV -- 2.5 PeV. Other signal models with different energy shape were also tested and some rejected.