New constraints on all flavor Galactic diffuse neutrino emission with the ANTARES telescope

Abstract

The flux of very high-energy neutrinos produced in our Galaxy by the interaction of accelerated cosmic rays with the interstellar medium is not yet determined. The characterization of this flux will shed light on Galactic accelerator features, gas distribution morphology and Galactic cosmic ray transport. The central Galactic plane can be the site of an enhanced neutrino production, thus leading to anisotropies in the extraterrestrial neutrino signal as measured by the IceCube Collaboration. The ANTARES neutrino telescope, located in the Mediterranean Sea, offers a favorable view of this part of the sky, thereby allowing for a contribution to the determination of this flux. The expected diffuse Galactic neutrino emission can be obtained, linking a model of generation and propagation of cosmic rays with the morphology of the gas distribution in the Milky Way. In this paper, the so-called “gamma model” introduced recently to explain the high-energy gamma-ray diffuse Galactic emission is assumed as reference. The neutrino flux predicted by the “gamma model” depends on the assumed primary cosmic ray spectrum cutoff. Considering a radially dependent diffusion coefficient, this proposed scenario is able to account for the local cosmic ray measurements, as well as for the Galactic gamma-ray observations. Nine years of ANTARES data are used in this work to search for a possible Galactic contribution according to this scenario. All flavor neutrino interactions are considered. No excess of events is observed, and an upper limit is set on the neutrino flux of 1.1 (1.2) times the prediction of the “gamma model,” assuming the primary cosmic ray spectrum cutoff at 5 (50) PeV. This limit excludes the diffuse Galactic neutrino emission as the major cause of the “spectral anomaly” between the two hemispheres measured by IceCube.Postprint (author's final draft

High Energy Neutrino expectations from the Central Molecular Zone

“…From this region of the sky, a even better sensitivity can be expected from the ANTARES telescope when looking for point-like source through all-flavor analysis [24]. The observation of the CMZ through muonic neutrino channel can be complementary to the analyses focused on a larger portion of Galactic plane, like the one recently published by the ANTARES collaboration (for the region |l| < 40 • and |b| < 3 • ) [22] to understand the emission related to Galactic CRs interaction with the molecular gas. A detailed study of the full CMZ region (≤ 600 parsecs) will became possible in a near future with the incoming KM3NeT/ARCA Mediterranean observatory [25].…”

“…constrain the different models of CR sea diffuse emission, with a big improvement expected from ANTARES [22] and future KM3NeT/ARCA [23] observations, the most energetic HESE event collected around the GC by IceCube experiment can give us hints about the cutoff to be applied to the primary CRs. Looking over the 54 HESE events one of them (IC14) with measured energy of 1041…”

Search for correlations of high-energy neutrinos and ultrahigh- energy cosmic rays

“…South Pole, and +0.8, with the bulk of events originating from the Southern Hemisphere. This data set has been used in ANT's latest all-flavor point-source analysis [4].…”

Highlights of the ANTARES neutrino telescope results

“…Two different energy cut-offs for the primary protons producing neutrinos when interacting with the gas are considered. Only the results concerning the inner Galactic plane region are shown in the plot, though all-sky data have been used for the analysis [5].…”