2007A&A...464L..45K

We investigate the X-ray spectral and timing properties of the high mass X-ray binary EXO 2030+375 observed during its June-September 2006 giant (type II) outburst. The data analyzed in this work are from partly simultaneous observations with INTEGRAL and Swift. The pulse period P and its temporal derivative {dot}(P) are measured. X-ray pulse profiles in different energy ranges and time intervals are constructed. Pulse averaged X-ray spectra for different time intervals are studied. We report a strong spin-up of the source during the outburst, comparable to that observed in 1985 during the previous giant outburst when the source was discovered. The value of {dot}(P) is found to be linearly related to the X-ray luminosity of the source during the outburst. For the first time the hard X-ray (>25keV) characteristics of the source during a type II outburst are studied. The X-ray pulse profiles apparently change with luminosity. The X-ray spectral continuum in the 3-120keV energy range is modeled with an absorbed power law with an exponential cutoff around E∼26keV. An iron emission line at ∼6-7keV is observed. The spectrum reveals some features between 10 and 20keV which can be modeled either by a broad emission line at ∼13-15keV (a ``bump'') or by two absorption lines at ∼10 and ∼20keV.