Paper detail

X-ray pulsars through the eyes of INTEGRAL

Recent results of the spectral and timing analysis of X-ray pulsars in hard X-rays with the INTEGRAL observatory are reviewed. The evolution of the cyclotron line energy with the source luminosity was studied in detail for the first time for several sources. It was shown that for V0332+53 this dependence is linear, but for 4U0115+63 and A0535+262 it is more complicated. There are some evidences of the "reverse" evolution for GX301-2 and Her X-1, and no evolution was found for Vela X-1, Cen X-3, etc. A strong dependence of the pulse fraction on the energy and source luminosity was revealed and studied in detail. A prominent feature in the pulse fraction dependence on the energy was discovered near the cyclotron frequency for several bright sources. The obtained results are compared with results of observations in standard X-rays and briefly discussed in terms of current models; some preliminary explanations are proposed.