A new and improved IceCube point source analysis

The IceCube Neutrino Observatory, a cubic kilometer scale Cherenkov detector deployed in the deep ice at the geographic South Pole, investigates extreme astrophysical phenomena by studying the corresponding high-energy neutrino signal. Its discovery of a diffuse flux of astrophysical neutrinos with energies up to the PeV scale in 2013 has triggered a vast effort to identify the mostly unknown sources of these high energy neutrinos. Here, we present a new IceCube point-source search that improves the accuracy of the statistical analysis, especially at energies of a few TeV and below. The new approach is based on multidimensional kernel density estimation for the probability density functions and new estimators for the observables, namely the reconstructed energy and the estimated angular uncertainty on the reconstructed arrival direction. The more accurate analysis provides an improvement in discovery potential up to ∼30% over previous works for hard spectrum sources.

Mapping large-scale diffuse γ-ray emission in the 10−100 TeV band with Cherenkov telescopes

Context. Measurement of diffuse γ-ray emission from the Milky Way with Imaging Atmospheric Cherenkov Telescopes (IACT) is difficult because of the high level of charged cosmic ray background and the small field of view. Aims. We show that such a measurement is nevertheless possible in the energy band 10−100 TeV. Methods. The minimal charged particle background for IACTs is achieved by selecting the events to be used for the analyses of the cosmic ray electrons. Tight cuts on the event quality in these event selections allow us to obtain a sufficiently low background level to allow measurement of the diffuse Galactic γ-ray flux above 10 TeV. We calculated the sensitivities of different types of IACT arrays for the Galactic diffuse emission measurements and compared them with the diffuse γ-ray flux from different parts of the sky measured by the Fermi Large Area Telescope below 3 TeV and with the astrophysical neutrino signal measured by IceCube telescope. Results. We show that deep exposure of existing IACT systems is sufficient for detection of the diffuse flux from all the Galactic Plane up to Galactic latitude |b| ∼ 5°. The Medium Size Telescope array of the CTA will be able to detect the diffuse flux up 30° Galactic latitude. Its sensitivity will be sufficient for detection of the γ-ray counterpart of the Galactic component of the IceCube astrophysical neutrino signal above 10 TeV. We also propose that a dedicated IACT system composed of small but wide-field-of-view telescopes could be used to map the 10−100 TeV diffuse γ-ray emission from across the whole sky. Conclusions. Detection and detailed study of diffuse Galactic γ-ray emission in the previously unexplored 10−100 TeV energy range is possible with the IACT technique. This is important for identification of the Galactic component of the astrophysical neutrino signal and for understanding the propagation of cosmic rays in the interstellar medium.

Neutrino Sources from a Multi-Messenger Perspective

The field of high-energy neutrino astronomy is undergoing a rapid evolution. After the discovery of a diffuse flux of astrophysical TeV-PeV neutrinos in 2013, the Ice-Cube observatory has recently found first compelling evidence for neutrino emission from blazars. In this brief review, I will summarize the status of these neutrino observations and highlight the strong role of multi-messenger astronomy for their interpretation.

Gravitational waves and neutrinos joint searches in the Mediterranean Sea

The recent detection of gravitational waves (GW) have launched effectively the field of multimessenger astronomy. High energy neutrinos (HEN) have been detected as a diffuse flux and show indications of transient point sources. They can bring crucial informations on cataclysmic cosmic events by identifying hadrons acceleration to high energies and pointing back to the source at the degree level which is an asset for follow-up of GW events with photonic telescopes. We will review the current searches for joint sources of gravitational waves and high energy neutrinos performed with the ANTARES telescope and the perspectives offered by its successor KM3NeT.