TeV Gamma and Cosmic Ray Production in Supernova Remnants

Abstract

An information about high-energy CR population in SNRs can be obtained from gamma-ray observation. High-energy gamma-rays are produced by electronic and hadronic CR components in the inverse Compton (IC) scattering and in the hadronic collisions leading to pion production and subsequent decay respectively. SNe of type Ib and II are more numerous in our Galaxy. According to the theoretical prediction about 20 SNRs should be visible in the TeV gamma-rays whereas only two were detected up to now by SHALON, namely Tycho’s SNR and Geminga. The expected pion decay gamma-flux Fγ ∼ E−1 γ extends up to > 30TeV, whereas the IC gamma-ray flux has a cutoff above a few TeV. So, a detection of gamma-rays at energies of 10 40 TeV by SHALON is an evidence for hadron origin of the rays. An another class of objects considered as a particle accelerator in the Galaxy are Pulsar Wind Nebulae (PWN). One of them is Crab Nebula, observed through all bands of electromagnetic spectrum. Crab Nebula has an extraordinary broad spectrum, attributed to synchrotron radiation of electrons with energies from GeV to PeV. This continuous spectrum appears to terminate near 10 eV and photons, produced by relativistic electrons and positrons (∼ 10 eV) via Inverse Compton, form a new component of spectrum in GeV TeV energy range. The spectrum of gamma rays from the Crab Nebula has been measured in the energy range 0.8 TeV to 11 TeV at the SHALON Alatoo Observatory by the atmospheric Cerenkov technique. The integral energy spectrum is well described by the single power law I(> Eγ) ∝ E−1.44±0.07 γ . An image of gamma-ray emission from Crab Nebula by SHALON telescope is presented. The VHE spectral energy distribution of the Crab Nebula is compared with the predictions of a synchrotron self-Compton emission model in energy range 0.8 TeV to 11 TeV (Hillas et al. 1998).