A multi-epoch spectroscopic study of the BAL quasar APM 08279+5255: I. C IV absorption variability

Broad absorption lines indicate gas outflows with velocities from thousands of km s[sup -1] to about 0.2 the speed of light, which may be present in all quasars and may play a major role in the evolution of the host galaxy. The variability of absorption patterns can provide information on changes in the density and velocity distributions of the absorbing gas and its ionisation status. We want to accurately follow the evolution in time of the luminosity and both the broad and narrow CIV absorption features of an individual object, the quasar APM 08279+5255, and analyse the correlations among these quantities. The broad absorption behaviour suggests changes in the ionisation status as the main cause of variability. We show for the first time a correlation of this variability with the R band flux. The different behaviour of the narrow absorption system might be due to recombination time delay.