Rayonnement gamma des Noyaux Actifs de Galaxies observé aux Très Hautes Énergies avec H.E.S.S.: Études multi-longueurs d'onde et modélisation de processus radiatifs

Abstract : Active Galactic Nuclei (AGN) are among the most energetic sources in the Universe. A subgroup of AGN possesses relativistic jets, the emission of which is purely non-thermal. In the case where the jet is aligned to the line of sight, these objects, called "blazars", have their emission amplified by the relativistic Doppler effect. Since the advent of very high energy (VHE; E>100 GeV) gamma-ray astrophysics, Cherenkov telescopes like H.E.S.S. have observed almost thirty AGN, mainly blazars, from the ground. Cherenkov radiation from particle showers created by the interaction of gamma-rays in the terrestrial atmosphere is used to derive the properties of the incident photon and thus to study these extragalactic sources. We have studied the highly variable VHE gamma-ray emission from the blazar PKS 2155-304, from which two major outbursts were detected in July 2006, within the framework of a dynamic synchrotron self-Compton (SSC) model. This variable emission presents properties excluding the most standard emission scenarios for blazars. We have also developed an SSC emission model for misaligned relativistic jets, to interpret the recent discovery of VHE gamma-ray emission from two radio galaxies, M 87 and Cen A, which established the emergence of a new familiy of cosmic TeV emitters. We conclude with a systematic study conducted on all the AGN currently known at TeV with a stationary SSC model. We present tools for predictions of flux densities in these objects, which can be confronted with future observations by the Cherenkov Telescope Array (CTA).
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https://tel.archives-ouvertes.fr/tel-00431288
Contributor : Jean-Philippe Lenain <>
Submitted on : Wednesday, November 11, 2009 - 6:31:35 PM
Last modification on : Tuesday, December 10, 2019 - 4:16:03 PM
Long-term archiving on: Thursday, June 17, 2010 - 6:24:15 PM

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Jean-Philippe Lenain. Rayonnement gamma des Noyaux Actifs de Galaxies observé aux Très Hautes Énergies avec H.E.S.S.: Études multi-longueurs d'onde et modélisation de processus radiatifs. Astrophysique [astro-ph]. Observatoire de Paris, 2009. Français. ⟨tel-00431288⟩

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