Clumps in the stellar wind of Vela X-1
Rothschild, Richard E.; Fürst, Felix; Kretschmar, Peter; Staubert, Rüdiger; Wilms, Jörn; Santangelo, Andrea; Kreykenbohm, Ingo; Torrejòn, José Miguel
Germany, Spain, United States
Abstract
We present a detailed analysis of all public available INTEGRAL data of the HMXB pulsar Vela X-1. During the more active phases, Vela X-1 featured bright flares with a maximum intensity of more than 5 Crab, but at the same time also offstates during which the source was undetectable by INTEGRAL/ISGRI [1]. We interpret this behavior as a direct evidence for the strongly structured wind in Vela X-1. To study the flaring behavior, we performed a statistical analysis of the X-ray light curve. The resulting log-normal distributions show that also the mass of the clumps in the stellar wind is indeed log-normally distributed, as the X-ray intensity is a direct tracer of the mass accretion rate and thus also for the mass of the clumps.