X-ray reprocessing in accreting pulsar GX 301-2 observed with Insight-HXMT

We investigate the absorption and emission features in observations of GX 301-2 detected with Insight-HXMT/LE in 2017-2019. At different orbital phases, we found prominent Fe K alpha, K beta, and Ni K alpha lines, as well as Compton shoulders and Fe K-shell absorption edges. These features are due to the X-ray reprocessing caused by the interaction between the radiation from the source and surrounding accretion material. According to the ratio of iron lines (K alpha and K beta), we infer the accretion material is in a low ionization state. We find an orbital-dependent local absorption column density, which has a large value and strong variability around the periastron. We explain its variability as a result of inhomogeneities of the accretion environment and/or instabilities of accretion processes. In addition, the variable local column density is correlated with the equivalent width of the iron K alpha lines throughout the orbit, which suggests that the accretion material near the neutron star is spherically distributed.

Automated summary

In observations of GX 301-2, absorption and emission features were found, attributed to X-ray reprocessing. The low ionization state of the accretion material was inferred based on the iron line ratio, with the local column density showing significant variability around the periastron. The variable local column density was correlated with the equivalent width of the iron K alpha lines throughout the orbit, indicating a spherically distributed accretion material near the neutron star.