Xeff analysis method optimization to enhance IACTs performances

The seek of high precision analyses in $\gamma$-ray astronomy leads to the implementation of multivariate combination, benefiting from several reconstruction methods. Such analysis, called $X_{eff}$, was developed for the H.E.S.S. data using three shower reconstruction methods. This paper presents the improvement granted to this analysis by refining the distribution calculation of discriminant variables, considering observation conditions, and adding new variables in the $X_{eff}$ combination. The efficiency of the analysis is presented using simulations and real data. A comparison with the standard analysis (model++), for a typical set of sources, shows a significant gain in sensitivity.Comment: Contribution to the Proceedings of the 34th International Cosmic Ray Conference (ICRC 2015), The Hague, The Netherland

Optimization of multivariate analysis for IACT stereoscopic systems

Multivariate methods have been recently introduced and successfully applied for the discrimination of signal from background in the selection of genuine very-high energy gamma-ray events with the H.E.S.S. Imaging Atmospheric Cerenkov Telescope. The complementary performance of three independent reconstruction methods developed for the H.E.S.S. data analysis, namely Hillas, model and 3D-model suggests the optimization of their combination through the application of a resulting efficient multivariate estimator. In this work the boosted decision tree method is proposed leading to a significant increase in the signal over background ratio compared to the standard approaches. The improved sensitivity is also demonstrated through a comparative analysis of a set of benchmark astrophysical sources.Comment: 10 pages, 8 figures, 3 tables, accepted for publication in Astroparticle Physic

The Monoceros very-high-energy gamma-ray source

The H.E.S.S. telescope array has observed the complex Monoceros Loop SNR/Rosette Nebula region which contains unidentified high energy EGRET sources and potential very-high-energy (VHE) gamma-ray source. We announce the discovery of a new point-like VHE gamma-ray sources, HESS J0632+057. It is located close to the rim of the Monoceros SNR and has no clear counterpart at other wavelengths. Data from the NANTEN telescope have been used to investigate hadronic interactions with nearby molecular clouds. We found no evidence for a clear association. The VHE gamma-ray emission is possibly associated with the lower energy gamma-ray source 3EG J0634+0521, a weak X-ray source 1RXS J063258.3+054857 and the Be-star MWC 148.Comment: 4 pages, 4 figures, Contribution to the 30th ICRC, Merida Mexico, July 200

New unidentified H.E.S.S. Galactic sources

H.E.S.S. is one of the most sensitive instruments in the very high energy (VHE; > 100 GeV) gamma-ray domain and has revealed many new sources along the Galactic Plane. After the successful first VHE Galactic Plane Survey of 2004, H.E.S.S. has continued and extended that survey in 2005-2008, discovering a number of new sources, many of which are unidentified. Some of the unidentified H.E.S.S. sources have several positional counterparts and hence several different possible scenarios for the origin of the VHE gamma-ray emission; their identification remains unclear. Others have so far no counterparts at any other wavelength. Particularly, the lack of an X-ray counterpart puts serious constraints on emission models. Several newly discovered and still unidentified VHE sources are reported here.Comment: ICRC 2009 proceeding

The Role of the Scottish Renaissance in the (Re)construction of a Multilingual Identity Reverberating Internationally

Nous montrons que les acteurs de la renaissance écossaise entreprennent de raviver le sentiment national dormant afin de provoquer un mouvement social à la hauteur des aspirations nationales et internationales de la nation écossaise. En effet, nombre de modernistes écossais contribuent à la transformation du paysage intellectuel en Écosse dans le même temps qu’ils expriment leurs convictions politiques et qu’ils participent de manière plus ou moins active au mouvement nationaliste. Par conséquent, la nature polyphonique du modernisme en Écosse, élaborée à partir d’une idéologie artistique aux résonances multiples et contingentes à la fragmentation du mouvement nationaliste, génère une nouvelle vision de l’identité écossaise.This paper establishes that the agents of the Scottish renaissance took it on themselves to revive the dormant national feeling so as to trigger a national movement that might match the national and international expectations of the Scottish nation. Many Scottish modernists contributed to the transformation of the intellectual outlook of Scotland while simultaneously expressing their political convictions, thus participating more or less directly to the nationalist movement. As a consequence, the polyphonic nature of Scottish modernism, devised from an artistic ideology with multiple echoes and related to the fragmentation of the nationalist movement, breeds an new vision of Scottish identity

Boîtes de conserve de plus de soixante ans

Fiasson R. Boîtes de conserve de plus de soixante ans. In: Bulletin de l'Académie Vétérinaire de France tome 109 n°6, 1956. pp. 289-293