A new analysis strategy for detection of faint gamma-ray sources with Imaging Atmospheric Cherenkov Telescopes

Abstract

A new background rejection strategy for gamma-ray astrophysics with stereoscopic Imaging Atmospheric Cherenkov Telescopes (IACT), based on Monte Carlo (MC) simulations and real background data from the H.E.S.S. [High Energy Stereoscopic System, see [1].] experiment, is described. The analysis is based on a multivariate combination of both previously-known and newly-derived discriminant variables using the physical shower properties, as well as its multiple images, for a total of eight variables. Two of these new variables are defined thanks to a new energy evaluation procedure, which is also presented here. The method allows an enhanced sensitivity with the current generation of ground-based Cherenkov telescopes to be achieved, and at the same time its main features of rapidity and flexibility allow an easy generalization to any type of IACT. The robustness against Night Sky Background (NSB) variations of this approach is tested with MC simulated events. The overall consistency of the analysis chain has been checked by comparison of the real gamma-ray signal obtained from H.E.S.S. observations with MC simulations and through reconstruction of known source spectra. Finally, the performance has been evaluated by application to faint H.E.S.S. sources. The gain in sensitivity as compared to the best standard Hillas analysis ranges approximately from 1.2 to 1.8 depending on the source characteristics, which corresponds to an economy in observation time of a factor 1.4 to 3.2.

arXiv comment26 pages, 13 figures

References in corpus (14)

• Observations of the Crab Nebula with H.E.S.S
• The H.E.S.S. survey of the Inner Galaxy in very high-energy gamma-rays
• A high performance likelihood reconstruction of gamma-rays for Imaging Atmospheric Cherenkov Telescopes
• Discovery of very high energy gamma-ray emission from Centaurus A with H.E.S.S
• Gamma-Hadron Separation in Very-High-Energy gamma-ray astronomy using a multivariate analysis method
• Temporal and spectral gamma-ray properties of Mkn421 above 250 GeV from CAT observations between 1996 and 2000
• Very high energy gamma rays from the composite SNR G0.9+0.1
• Discovery of VHE gamma-rays from the distant BL Lac 1ES 0347-121
• Comparison of techniques to reconstruct VHE gamma-ray showers from multiple stereoscopic Cherenkov images
• A new analysis method for very high definition Imaging Atmospheric Cherenkov Telescopes as applied to the CAT telescope
• Selection and 3D-Reconstruction of Gamma-Ray-induced Air Showers with a Stereoscopic System of Atmospheric Cherenkov Telescopes
• Multi-wavelength Observations of H 2356-309
• Optimization of multivariate analysis for IACT stereoscopic systems
• Upgrading and testing the 3D reconstruction of gamma-ray air showers as observed with an array of Imaging Atmospheric Cherenkov telescopes

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