Hot disc of the Swift J0243.6+6124 revealed by Insight-HXMT. Issue 2 (22nd October 2019)

• Record Type: Journal Article
• Authors: Doroshenko, V; Zhang, S N; Santangelo, A; Ji, L; Tsygankov, S; Mushtukov, A; Qu, L J; Zhang, S; Ge, M Y; Chen, Y P; Bu, Q C; Cao, X L; Chang, Z; Chen, G; Chen, L; Chen, T X; Chen, Y; Chen, Y B; Cui, W; Cui, W W; Deng, J K; Dong, Y W; Du, Y Y; Fu, M X; Gao, G H; Gao, H; Gao, M; Gu, Y D; Guan, J; Guo, C C; Han, D W; Hu, W; Huang, Y; Huo, J; Jia, S M; Jiang, L H; Jiang, W C; Jin, J; Jin, Y J; Kong, L D; Li, B; Li, C K; Li, G; Li, M S; Li, T P; Li, W; Li, X; Li, X B; Li, X F; Li, Y G; Li, Z J; Li, Z W; Liang, X H; Liao, J Y; Liu, C Z; Liu, G Q; Liu, H W; Liu, S Z; Liu, X J; Liu, Y; Liu, Y N; Lu, B; Lu, F J; Lu, X F; Luo, T; Ma, X; Meng, B; Nang, Y; Nie, J Y; Ou, G; Sai, N; Shang, R C; Song, L M; Song, X Y; Sun, L; Tan, Y; Tao, L; Tuo, Y L; Wang, G F; Wang, J; Wang, W S; Wang, Y S; Wen, X Y; Wu, B B; Wu, M; Xiao, G C; Xiong, S L; Xu, H; Xu, Y P; Yang, Y R; Yang, J W; Yang, S; Yang, Y J; Zhang, A M; Zhang, C L; Zhang, C M; Zhang, F; Zhang, H M; Zhang, J; Zhang, Q; Zhang, T; Zhang, W; Zhang, W C; Zhang, W Z; Zhang, Y; Zhang, Y; Zhang, Y F; Zhang, Y J; Zhang, Z; Zhang, Z L; Zhao, H S; Zhao, J L; Zhao, X F; Zheng, S J; Zhu, Y; Zhu, Y X; Zou, C L; Zhang, R L;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 491:Issue 2(2020)
• Page Start: 1857
• Page End: 1867
• Publication Date: 2019-10-22
• Subjects: accretion, accretion discs -- stars: magnetic field -- stars: neutron -- pulsars: general -- pulsars: individual: Swift J0243.6+6124 -- X-rays: binaries; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz2879
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We report on analysis of observations of the bright transient X-ray pulsar (XRP) Swift J0243.6+6124 obtained during its 2017–2018 giant outburst with Insight-HXMT, NuSTAR, and Swift observatories. We focus on the discovery of a sharp state transition of the timing and spectral properties of the source at super-Eddington accretion rates, which we associate with the transition of the accretion disc to a radiation pressure dominated state, the first ever directly observed for magnetized neutron star. This transition occurs at slightly higher luminosity compared to already reported transition of the source from sub- to supercritical accretion regime associate with onset of an accretion column. We argue that this scenario can only be realized for comparatively weakly magnetized neutron star, not dissimilar to other ultra-luminous X-ray pulsars, which accrete at similar rates. Further evidence for this conclusion is provided by the non-detection of the transition to the propeller state in quiescence which strongly implies compact magnetosphere and thus rules out magnetar-like fields.