Evidence bearing on the interaction of gas and high-energy particles in quasi-stellar objects

Abstract

Large fluxes of high-energy electrons are responsible for the non-thermal radio fluxes and probably the optical continua from compact sources in quasistellar objects. If they are accompanied by energetic fluxes of protons with energies 100 MeV, we expect that interaction with the gas that is responsible for the line spectra will lead to spallation. Among the primary spallation products is the element boron with the lines BIll λ.2066.3 and BIIλ, 1362.46 which would be detectable in QSO spectra. These lines have been looked for in the spectra of a number of QSO's listed in Tables 1 and 2. They are absent, and by analyzing the ionization structure of the emitting and absorbing regions we find that the limit to the boron to carbon radio is N(B)/N(C)≤1/15. Since the composition of the gas is normal, and no boron can be detected we show: (i) that the gas cannot have originated in the very central regions of the continuum source with sizes 1 pc, since even exposure to large fluxes of protons for a short time (< 1 year) would have led to gross changes in composition. (ii) For a specific model, in which it is supposed that the proton flux diffuses through the emission~line region of the gas we find that in order that N(B)/N(C)≤1/15, the flux of protons with mean energy 100 MeV must be 4 10⁵³ erg, or about 10^-4 ofthe energy carried by the electrons in the most powerful continuum sources. With different models, more stringent limits could be set. It is concluded either that the proton flux is small, or that the particles do not interact significantly with the gas because they are ejected axisymmetrically and the ejection is confined to a very small solid angle. Such a geometry is suggested by the radio data.