X-ray pulsars through the eyes of INTEGRAL

TL;DR

This paper reviews recent INTEGRAL observations of X-ray pulsars, focusing on spectral and timing analysis, cyclotron line evolution, and pulse fraction dependence, providing new insights into pulsar magnetic fields and emission mechanisms.

Contribution

It presents the first detailed study of cyclotron line energy dependence on luminosity for multiple sources and compares these findings with standard X-ray observations.

Findings

Cyclotron line energy dependence varies among sources, with some showing linear and others more complex relations.

Pulse fraction strongly depends on energy and luminosity, with features near the cyclotron frequency.

Evidence of 'reverse' evolution of cyclotron lines in some sources was found.

Abstract

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.