X-ray time variability and luminosity correlations in BL lacertae objects
Maccagni, D.; Giommi, P.; Garilli, B.; Barr, P.; Pollock, A.
Netherlands, Italy
Abstract
We present the preliminary results of a study of the soft X-ray properties of a sample of 34 BL Lacertae objects observed with the the EXOSAT Observatory. Strong correlations between the X-ray, optical and radio fluxes have been found in the subsample of X-ray selected objects. X-ray variability is common and has been significantly detected in 14 (8 × ray-selected and 6 radio-selected) out of the 25 objects observed more than once. Flux variations by up to a factor 5 have been found. The commonest form of variability encountered consists of small amplitude variations about a quiescent flux level whose mean value remains roughly constant over time scales of years.