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Recherche de photons pulsés au-dessus de 30 GeV dans le pulsar du Crabe et PSR B1951+32 avec le détecteur Tchérenkov atmosphérique CELESTE

Abstract : Based on the reconversion of the solar power plant THEMIS (French Pyrenees) into a telescope for gamma ray astronomy, CELESTE is the first experiment to explore the spectrum between 10 GeV and 300 GeV and thus to connect satellite domain to that of ground based imaging telescopes. This energy range is particularly important for pulsar studies. Indeed, none of the six high energy pulsars detected by EGRET has been detected at ground level. Two ideal models aim to explain the observed cutoff in the spectra between 1 and 100 GeV: Polar Cap and Outer Gap. Those differ however in several points and a detection in this energy range would give information to clear up the situation. This thesis is the first work dedicated to pulsar study with CELESTE, and more specifically for two candidates: the Crab pulsar and PSR B1951+32. The search for a pulsed signal signal implies an analysis somewhat different from that developed for the steady sources. The first step was to adapt the barycentric dating procedure to pulsars to CELESTE. Next, a dedicated analysis was developed to preserve low energy where a possible signal is expected. Thus, combining the assets of previous analysis and the characteristics of electromagnetic and hadronic showers below 50 GeV, specific background rejection criteria have been established and applied to the data. The results primarily lie in the establishment of new upper limits for the energy cutoff for the two observed pulsars. While those are insufficient to strongly constrain models, they are the first measurements in this energy range, and thus remain of special interest for the physics of these objects. However, an excess is observed on Crab data but with an insufficient significance. As this indication of modulation exhibits the expected properties, it was expressed as a flux for the hypothesis of a pulsed signal, then interpreted. If new observations come to confirm this excess, the present work would be the first detection around 30 GeV. In such a case, the Polar Cap model could be called into question.
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Contributor : Emmanuel Durand <>
Submitted on : Tuesday, May 13, 2003 - 10:15:04 AM
Last modification on : Thursday, January 11, 2018 - 6:12:51 AM
Long-term archiving on: : Tuesday, September 11, 2012 - 8:25:16 PM


  • HAL Id : tel-00002815, version 1



Emmanuel Durand. Recherche de photons pulsés au-dessus de 30 GeV dans le pulsar du Crabe et PSR B1951+32 avec le détecteur Tchérenkov atmosphérique CELESTE. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Sciences et Technologies - Bordeaux I, 2003. Français. ⟨tel-00002815⟩



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