INTEGRAL and Swift observations of EXO 2030+375 during a giant outburst

Aims. 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. Methods. The data analyzed in this work are from partly simultaneous observations with INTEGRAL and Swift. The pulse period P and its temporal derivative. 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. Results. 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. 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 (> 25 keV) 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 - 120 keV energy range is modeled with an absorbed power law with an exponential cutoff around E similar to 26 keV. An iron emission line at similar to 6 - 7 keV is observed. The spectrum reveals some features between 10 and 20 keV which can be modeled either by a broad emission line at similar to 13 - 15 keV ( a bump) or by two absorption lines at similar to 10 and similar to 20 keV.