Publications by Year: 1989

1989
Kirk JG, Mastichiadis A. Neutrons from active galactic nuclei. [Internet]. 1989;213:75 - 79. WebsiteAbstract
A recently proposed acceleration mechanism for ultra relativistic particles in the central engines of AGN's suggests that protons are the particles which are accelerated initially, and that these subsequently inject the electrons and positrons supposed responsible for the continuum emission. This model necessarily leads to the prediction of a strong flux of neutrons (with a luminosity at least as great as that in the photon continuum) from the central engine. We investigate some of the consequences of such a model. In particular, the neutron flux will, by means of spallation reactions, produce amounts of boron in the surrounding material which it may be possible to observe in the optical spectrum. In addition, the central engine will act as a source of high energy gamma-rays. Those which can propagate to the Earth (i.e., those with energy < 10^14^ eV) may be observed directly, whereas those of higher energy will be absorbed by radio photons from either the microwave background or the AGN itself. If this occurs in a typical interstellar magnetic field, the energy of the gamma-rays will be reradiated in the form of X-rays.
Mastichiadis A, Kylafis N, Ventura J. Supernova 1987A : envelope metallicity and the nature of the soft X-ray component. [Internet]. 1989;208:L11 - L14. WebsiteAbstract
The observed X-ray spectra reported by the GINGA and MIR-HEXE satellite experiments contain information on the metallicity of the Supernova's expanding envelope. Using a Monte Carlo code to simulate the Compton degradation of the ^56^Co -produced γ-rays, we calculate the emerging X-ray spectrum for various metallicities. The observed spectra are compatible with a low (less than solar) metal abundance, while an additional soft component, independent of the ^56^Co source is probably required in order to account for the data. The evolution of the spectral hardness is used as a sensitive indicator of the nature of the soft component, and of the possible contribution of an imbedded pulsar to the X-ray spectrum.