The Giant Radio Array for Neutrino Detection

High-energy neutrino astronomy will probe the working of the most violent phenomena in the Universe. The Giant Radio Array for Neutrino Detection (GRAND) project consists of an array of ∼ 105 radio antennas deployed over ∼ 200 000 km2 in a mountainous site. It aims at detecting high-energy neutrinos via the measurement of air showers induced by the decay in the atmosphere of τ leptons produced by the interaction of cosmic neutrinos under the Earth surface. Our objective with GRAND is to reach a neutrino sensitivity of 5 × 10−11E−2 GeV−1 cm−2 s−1 sr−1 above 3 × 1016 eV. This sensitivity ensures the detection of cosmogenic neutrinos in the most pessimistic source models, and up to 100 events per year are expected for the standard models. GRAND would also probe the neutrino signals produced at the potential sources of UHECRs

The Third Fermi Large Area Telescope Catalog of Gamma-ray Pulsars

We present 294 pulsars found in GeV data from the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. Another 33 millisecond pulsars (MSPs) discovered in deep radio searches of LAT sources will likely reveal pulsations once phase-connected rotation ephemerides are achieved. A further dozen optical and/or X-ray binary systems co-located with LAT sources also likely harbor gamma-ray MSPs. This catalog thus reports roughly 340 gamma-ray pulsars and candidates, 10% of all known pulsars, compared to $\leq 11$ known before Fermi. Half of the gamma-ray pulsars are young. Of these, the half that are undetected in radio have a broader Galactic latitude distribution than the young radio-loud pulsars. The others are MSPs, with 6 undetected in radio. Overall, >235 are bright enough above 50 MeV to fit the pulse profile, the energy spectrum, or both. For the common two-peaked profiles, the gamma-ray peak closest to the magnetic pole crossing generally has a softer spectrum. The spectral energy distributions tend to narrow as the spindown power $\dot E$ decreases to its observed minimum near $10^{33}$ erg s$^{-1}$, approaching the shape for synchrotron radiation from monoenergetic electrons. We calculate gamma-ray luminosities when distances are available. Our all-sky gamma-ray sensitivity map is useful for population syntheses. The electronic catalog version provides gamma-ray pulsar ephemerides, properties and fit results to guide and be compared with modeling results.Comment: 142 pages. Accepted by the Astrophysical Journal Supplemen

Spectroscopie résolue en phase de pulsars gamma millisecondes

The Fermi gamma-ray telescope, launched in August 2008, has opened a new window in the pulsar physics. Hardly half of the pulsed source detections corresponds to old re-accelerated neutron stars, the millisecond pulsars. The spectral analysis of the pulsed emission is crucial to constrain the theorical models describing the particle acceleration processes in the pulsar magnetosphere. This thesis focus on the systematical spectral study of 25 millisecond gamma-ray pulsars in the energy band : 50 MeV — 170 GeV. With 60 months of observations, we obtained and characterized the spectra of the total emission and the emission in characteristic rotational phase intervals. We looked at the global trends that could exist between the neutron star characteristics such as the spin-down power and the emission spectral properties. We studied as well the evolution of the latter across the rotational phase and their dependence with the morphological parameters of the light curves provided by a decomposition in morphological components of the gamma-ray profiles. These analyses shown unprecedented spectral and energetic trends. We compared the obtained results with the theoretical predictions and the previous observations. We discussed their implications on the radiation origin in regions where the magnetic field parallel electric field component is more or less efficiently screened and on the emission processes taking place.Le télescope gamma Fermi, lancé en Août 2008, a ouvert une nouvelle fenêtre dans la physique des pulsars. Presque la moitié des détections de sources gamma pulsées correspond à des étoiles à neutrons âgées ré-accélérées, les pulsars milliseconde. L'analyse spectrale des émissions pulsées est essentielle pour contraindre les modèles théoriques décrivant les processus d'accélération de particules dans la magnétosphère des pulsars. Cette thèse se concentre sur l'étude spectrale systématique de 25 pulsars gamma milliseconde dans la bande en énergie comprise entre 50 MeV et 170 GeV. En utilisant 60 mois de données, nous avons pu obtenir et caractériser les spectres de l'émission pulsée totale et dans différentes parties caractéristiques de la courbe de lumière. Nous nous sommes intéressés aux tendances globales pouvant exister entre les caractéristiques des étoiles à neutrons, telles que la luminosité de ralentissement et les propriétés spectrales de l'émission. Nous avons également étudié l'évolution des propriétés spectrales à travers la phase rotationnelle et leurs dépendances avec les paramètres morphologiques des courbes de lumière provenant d'une décomposition en composante morphologique des profils gamma pulsés. Ces analyses ont montré des tendances spectrales et énergétiques inédites. Nous avons comparé les résultats obtenus avec les prédictions théoriques et les observations antérieures. Nous avons discuté leurs implications sur l'origine des radiations dans les régions où la composante du champ électrique parallèle au champ magnétique est plus ou moins efficacement écrantée et sur les processus d'émission mis en jeu

Radio Morphing: towards a fast computation of the radio signal from air showers

International audienceOver the last years, radio detection has matured to become a competitive method for the detection of air showers. Arrays of thousands of antennas are now envisioned for the detection of cosmic rays of ultra high energy or neutrinos of astrophysical origin. The data exploitation of such detectors requires to run massive air-shower simulations to evaluate the radio signal at each antenna position. In order to reduce the associated computational cost, we have developed a semi-analytical method for the computation of the emitted radio signal called Radio Morphing . The method consists in computing the radio signal of any air-shower at any location from the simulation of one single reference shower at given positions by (i) a scaling of the electric-field amplitude of this reference shower, (ii) an isometry on the simulated positions and (iii) an interpolation of the radio pulse at the desired position. This technique enables one to compute electric field time traces with characteristics very similar to those obtained with standard computation methods, but with computation times reduced by several orders of magnitude. In this paper, we present this novel tool, explain its methodology, and discuss its limitations. Furthermore, we validate the method on a typical event set for the future GRAND experiment showing that the calculated peak amplitudes are consistent with the results from ZHAireS simulations with a mean offset of +8.5 % and a standard deviation of 27.2% in this specific case. This overestimation of the signal strength by Radio Morphing arises mainly from the choice of the underlying reference shower

IVOA Provenance Data Model Version 1.0

This document describes how provenance information can be modeled, stored and exchanged within the astronomical community in a standardized way. We follow the definition of provenance as proposed by the W3C, i.e. that "provenance is information about entities, activities, and people involved in producing a piece of data or thing, which can be used to form assessments about its quality, reliability or trustworthiness." Such provenance information in astronomy is important to enable any scientist to trace back the origin of a dataset (e.g. an image, spectrum, catalog or single points in a spectral energy distribution diagram or a light curve), a document (e.g. an article, a technical note) or a device (e.g. a camera, a telescope), learn about the people and organizations involved in a project and assess the reliability, quality as well as the usefulness of the dataset, document or device for her own scientific work

IVOA Provenance Data Model Version 1.0

This document describes how provenance information can be modeled, stored and exchanged within the astronomical community in a standardized way. We follow the definition of provenance as proposed by the W3C, i.e. that "provenance is information about entities, activities, and people involved in producing a piece of data or thing, which can be used to form assessments about its quality, reliability or trustworthiness." Such provenance information in astronomy is important to enable any scientist to trace back the origin of a dataset (e.g. an image, spectrum, catalog or single points in a spectral energy distribution diagram or a light curve), a document (e.g. an article, a technical note) or a device (e.g. a camera, a telescope), learn about the people and organizations involved in a project and assess the reliability, quality as well as the usefulness of the dataset, document or device for her own scientific work

Radio morphing - towards a fast computation of the radio signal from air-showers

International audienceOver the last decades, radio detection of air showers has been established as a promising detection technique for ultrahigh-energy cosmic rays and neutrinos. Very large or dense antenna arrays are necessary to be proficient at collecting information about these particles and understanding their properties accurately. The exploitation of such arrays requires to run massive air-shower simulations to evaluate the radio signal at each antenna position, taking into account features such as the ground topology. In order to reduce computational costs, we have developed a fast computation of the emitted radio signal on the basis of generic shower simulations, called Radio Morphing. The method consists in the calculation of the radio signal of any air-shower by i) a scaling of the electric-field amplitude of a reference air shower to the target shower, ii) an isometry on the simulated positions and iii) an interpolation of the radio pulse at the desired position. This technique enables one to gain many orders of magnitude in CPU time compared to a standard computation. In this contribution, we present this novel tool and explain its methodology. In particular, Radio Morphing will be a key element for the simulation chain of the Giant Radio Array for Neutrino Detection (GRAND) project, that aims at detecting ultra-high-energy neutrinos with an array of 200 000 radio antennas in mountainous regions

The Giant Radio Array for Neutrino Detection

International audienceHigh-energy neutrino astronomy will probe the working of the most violent phenomena in the Universe. The Giant Radio Array for Neutrino Detection (GRAND) project consists of an array of ~ 10^5 radio antennas deployed over ~200000km^2 in a mountainous site. It aims at detecting high-energy neutrinos via the measurement of air showers induced by the decay in the atmosphere of tau leptons produced by the interaction of cosmic neutrinos under the Earth surface. Our objective with GRAND is to reach a neutrino sensitivity of 5 x 10^-11E^-2GeV^-1cm^-2s^-1sr^-1 above 3 x 10^16eV. This sensitivity ensures the detection of cosmogenic neutrinos in the most pessimistic source models, and up to 100 events per year are expected for the standard models. GRAND would also probe the neutrino signals produced at the potential sources of UHECRs