Disc versus wind accretion in X-ray pulsar GX 301-2

ABSTRACT GX 301-2 provides a rare opportunity to study both disc and wind accretion in a same target. We report Insight-Hard X-ray Modulation Telescope observations of the spin-up event of GX 301-2 that happened in 2019 and compare with those of wind-fed state. The pulse profiles of the initial rapi...

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Veröffentlicht in:Monthly notices of the Royal Astronomical Society 2021-06, Vol.504 (2), p.2493-2500
Hauptverfasser: Liu, Jiren, Ji, Long, Jenke, Peter A, Doroshenko, Victor, Liao, Zhenxuan, Li, Xiaobo, Zhang, Shuangnan, Orlandini, Mauro, Ge, Mingyu, Zhang, Shu, Santangelo, Andrea
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Sprache:eng
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Zusammenfassung:ABSTRACT GX 301-2 provides a rare opportunity to study both disc and wind accretion in a same target. We report Insight-Hard X-ray Modulation Telescope observations of the spin-up event of GX 301-2 that happened in 2019 and compare with those of wind-fed state. The pulse profiles of the initial rapid spin-up period are dominated by one main peak, while those of the later slow spin-up period are composed of two similar peaks, as those of wind-fed state. These behaviours are confirmed by Fermi/Gamma-ray Burst Monitor data, which also show that during the rapid spin-up period, the main peak increases with luminosity up to 8 × 1037 erg s−1, but the faint peak remains almost constant. The absorption column densities during the spin-up period are ∼1.5 × 1023 cm−2, much less than those of wind-fed state at similar luminosity (∼9 × 1023 cm−2), supporting the scenario that most of material is condensed into a disc during the spin-up period. We discuss possible differences between disc and wind accretion that may explain the observed different trends of pulse profiles.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stab938