Cherenkov line radiation and the emission-line spectra of QSOs

Cerenkov effect in a gaseous medium is discussed. It is pointed out that relativistic electrons with an isotropic distribution of velocities, when moving through a dense gas, will produce broad atomic emission lines with an asymmetric profile, the slope on the short wave side being much steeper than on the long wave side. Calculation for the hydrogen atom shows that the width of the L/sub α/ line may be 60 A or larger, for a gas density of N = 5 x 1020 cm-3. According to this radiation mechanism, the emission-line spectra of quasars can be interpreted satisfactorily