Chinese Acad Sci, Inst High Energy Phys, High Energy Astrophys Lab, Beijing 100039, Peoples R China
A geometrically thick dusty torus in NGC 1068 has been unambiguously resolved by an infrared interferometry telescope. This implies that clouds composing the dusty torus are undergoing supersonic collisions with each other. We show that the collisions form strong nonrelativistic shocks, which accelerate populations of relativistic electrons. The torus reprocesses emission from the accretion disk into an infrared band. We show that the energy density of the infrared photons inside the torus is much higher than that of the magnetic field in the clouds, and the seed photons of inverse Compton scattering are mainly from the infrared. The maximum energy of the relativistic electrons can reach a Lorentz factor of 10(5). We calculate the spectrum of the synchrotron and inverse Compton scattering radiation from the electrons in the torus. The relativistic electrons in the torus radiate non-thermal emission from radio to gamma-ray, which isotropically diffuses in the region of the torus. We find that the most prominent character is a peak at similar to0.5-1 GeV. We apply this model to NGC 1068 and find that the observed radio emission from the core component S-1 can be explained by the synchrotron emission from the relativistic electrons. We predict that there is gamma-ray emission with a luminosity of ergs 10(40) s(-1) peaking at similar to1 GeV from 40 10 the torus, which could be detected by the Gamma-Ray Large-Array Space Telescope in the future. This will provide a new clue to understanding the physics in the torus. The nonthermal radiation from the dusty torus may explain the radio emission from Seyfert galaxies. The cosmological implications of the nonthermal emission to the gamma-ray background radiation are also discussed.