The Thomson depth of sources radiating at the efficiency limit must lie near unity. This allows us to deduce a general condition on the maximum electron temperature attainable in such a source via two-body relaxation; \(kT_e < 22\) keV. The application of this result to the rapid variability observed in NGC 6814 and Cygnus X-l and to NGC 4151 is discussed.
Full paper : PDF 193K
@journal(Guilbert+Stepney:1982:MNRAS, author = "Paul W. Guilbert and A. C. Fabian and Susan Stepney", title = "Electron-ion coupling in rapidly varying sources", journal = "Monthly Notices of the Royal Astronomical Society", volume = 199, pages = "19P-21P", year = 1982 )