Dips and Offstates in High mass X-ray binaries

Presentation duration: 30 minutes

Presenter: Ingo Kreykenbohm

We present a detailed study of the absorption and dipping behavior of the accreting High Mass X-ray Binary GX 301-2. We use data from the XMM-Newton observatory to study the low energy continuum and the iron line complex and data from the Rossi X-ray Timing Explorer (RXTE) to model the continuum and study lightcurves. The analysis of the RXTE data shows that the source is strongly variable: the source exhibits intense flaring as well as dipping activity. The source countrate as recorded by the RXTE-PCA drops to almost zero during some of the dips in the lightcurve. A similar dipping behavior has been observed in the Vela X-1 (Kreykenbohm et al. 2008) as well as a number of other massive wind accreting sources. We present a detailed spectral and temporal study of the dips and discuss possible scenarios to explain the dips. The high quality XMM timing mode data are taken during the pre-periastron flare. We accumulate spectra with an exposure time of 30 seconds. Keeping the continuum parameters fixed, we obtain the column density NH and the iron line parameters for each of these short spectra. We can therefore track the evolution of the NH and the iron line and thus the absorbing material with very high time resolution, showing that the density of the absorbing material varies strongly on timescales of 100 seconds or less.

Gogus, E.
Fuerst, F.
Belloni, T.
Wilms, J.
Suchy, S.
Rothschild, R.E.