Insight-HXMT observations of Swift J0243.6+6124: the evolution of RMS pulse fractions at super-Eddington luminosity

Wang, P J; Kong, L. D.; Zhang, S; Chen, Y P; Zhang, S N; Qu, J. L.; Ji, Long; Tao, Lian; Ge, Ming-Yu; Lu, Fangjun; Chen, L; Song, Liming; Li, T P; Xu, Yupeng; Cao, X. L.; Chen, Y; Liu, C Z; Bu, Q. C.; Cai, C.; Chang, Zhi; Chen, G; Chen, T X; Chen, Y B; Cui, Wei; Cui, Weiwei; Deng, J. K.; Dong, Yongwei; Du, Y. Y.; Fu, M. X.; Gao, G. H.; Gao, He; Gao, Min; Gu, Y. D.; Guan, J.; Guo, Chengcheng; Han, Danxiang; Huang, Y.; Jia, Haiqiang; Jia, S. M.; Jiang, Luhua; Jiang, Weichun; Jin, J.; Jin, Yongjie; Li, B; Li, C K; Li, G; Li, M S; Li, W; Li, X; Li, X B; Li, X F; Li, Y G; Li, Z W; Liang, X. H.; Liao, J. Y.; Liu, B S; Liu, G Q; Liu, Hanwei; Liu, X J; Liu, Y N; Lü, Bo; Lu, X. F.; Luo, Q.; Luo, T.; Ma, Xiang; Meng, Bin; Nang, Y.; Nie, J. Y.; Ou, G.; Sai, N.; Shang, R. C.; Song, X. Y.; Sun, Liang; Tan, Ying; Tuo, You-Li; Wang, Chunling; Wang, G F; Wang, J; Wang, L. J.; Wang, W S; Wang, Y S; Wen, Xiang-Yang; Wu, B. Y.; Wu, B. B.; Wu, Mei‐Hwan; Xiao, G. C.; Xiao, Shuo; Xiong, S. L.; Yang, Jiawei; Yang, S.; Yang, Yun-Cheng; Yang, Yi; Yi, Q. B.; Yin, Q. Q.; You, Y.; Zhang, A M; Zhang, C M; Zhang, F; Zhang, H M; Zhang, J; Zhang, T; Zhang, W C; Zhang, W; Zhang, W Z; Zhang, Y F; Zhang, Yajiu; Zhang, Y; Zhang, Zhao; Zhang, Zhi; Zhang, Z L; Zhao, H. S.; Zhao, Xiaofan; Zheng, S.; Zheng, Y. G.; Zhou, D. K.; Zhou, Jianfeng; Zhu, Yuxuan; Zhuang, R. L.

doi:10.1093/mnras/staa2448

Cited by 13 publications

(8 citation statements)

References 27 publications

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“…rising phase, even though the accretion rate is the same in both cases. This might be related to the hysteresis effects of spectral and temporal properties reported by other authors (e.g., Doroshenko et al 2017;Wang et al 2020;Kong et al 2021). The physical mechanism is still poorly known.…”

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confidence: 88%

Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst

et al. 2023

ApJ

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We report on pulse profile decomposition analysis of bright transient X-ray pulsar 1A 0535+262 using broadband Insight-HXMT observations during a giant outburst of the source in 2020. We show that the observed pulse profile shape can be described in terms of a combination of two symmetric single-pole contributions for a wide range of energies and luminosities for a fixed geometry defining the basic geometry of the pulsar. This corresponds to a slightly distorted dipole magnetic field, i.e., one pole has to be offset by ∼12° from the antipodal position of the other pole. We reconstruct the intrinsic beam patterns of the pulsar assuming that the geometry is recovered from the decomposition analysis, and we find evidence for a transition between “pencil” and “fan” beams in energy ranges above the cyclotron line energy, which can be interpreted as a transition from sub- to supercritical accretion regimes associated with the onset of an accretion column. At lower energies, however, the beam pattern appears to be more complex and contains a substantial “fan” beam and an additional “pencil” beam component at all luminosities. The latter is not related to the accretion rate and is stronger in the fading phase of the outburst. We finally discuss the results in the context of other observational and theoretical findings earlier reported for the source in the literature.

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confidence: 88%

Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst

et al. 2023

ApJ

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“…We use the rms pulse fraction to quantify the pulse profile. The rms pulse fraction is defined as follows (Wilson-Hodge et al 2018;Wang et al 2020):…”

Section: Energy-luminosity Dependence Of the Pulsed Fractionmentioning

confidence: 99%

Timing Properties of the X-Ray Accreting Pulsar 1A 0535+262 Studied with Insight-HXMT

Wang

Kong

Zhang³

et al. 2022

ApJ

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We report results on the timing analysis of the 2020 giant outburst of 1A 0535+262, using broadband data from Insight-HXMT. The analysis of the pulse profile evolution from the subcritical-luminosity to the supercritical-luminosity regime is presented for the first time. We found that the observed pulse profile exhibits a complex dependence on both energy and luminosity. A dip structure at the energy of the cyclotron resonant scattering features is found for the first time in the pulse fraction–energy relation of 1A 0535+262, when the outburst evolves in a luminosity range from 4.8 × 1037 to 1.0 × 1038 erg s−1. The observed structure is luminosity dependent and appears around the source critical luminosity (∼6.7 × 1037 erg s−1).

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“…The pulsed fraction is ∼ 30%. The dependence of PF on the energy of photons may be found in Tao et al (2019) or Wang et al (2020). Note that as we did not do phase-connection between individual observations, Fig.…”

Section: Timing Analysismentioning

confidence: 86%

“…Insight-HXMT provided broadband X-ray data with high cadence (Zhang et al 2019;Kong et al 2020;Wang et al 2020). Using these data Doroshenko et al (2020) reported specific changes in timing and spectral properties of the pulsar.…”

Section: Introductionmentioning

confidence: 99%

ULX pulsar Swift J0243.6+6124 observations with NuSTAR -- dominance of reflected emission in the super-Eddington state

Bykov,

Gilfanov,

Tsygankov

et al. 2022

Preprint

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We report the discovery of the bright reflected emission component in the super-Eddington state of the ULX pulsar Swift J0243.6+6124, based on the NuSTAR observations of the source during its 2017 outburst. The flux of the reflected emission is weakly variable over the pulsar phase while the direct emission shows significantly larger pulsation amplitude. We propose that in this system the neutron star finds itself in the centre of the well formed by the inner edge of the geometrically thick super-Eddington accretion disc truncated by the magnetic field of the pulsar. The aspect ratio of the well is 𝐻/𝑅 ∼ 1. The inner edge of the truncated disc is continuously illuminated by the emission of the accretion column giving rise to the weakly variable reflected emission. As the neutron star rotates, its emission sweeps through the line of sight, giving rise to the pulsating direct emission. From Doppler broadening of the iron line, we measure the truncation radius of the accretion disc ∼ 50 𝑅 g . The inferred dipole component of the magnetic field is consistent with previous estimates favouring a not very strong field. The uniqueness of this system is determined by its moderately super-Eddington accretion rate and the moderate magnetic field so that the inner edge of the truncated geometrically thick accretion disc is seen from the neutron star at a large solid angle.

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Insight-HXMT observations of Swift J0243.6+6124: the evolution of RMS pulse fractions at super-Eddington luminosity

Cited by 13 publications

References 27 publications

Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst

Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst

Timing Properties of the X-Ray Accreting Pulsar 1A 0535+262 Studied with Insight-HXMT

ULX pulsar Swift J0243.6+6124 observations with NuSTAR -- dominance of reflected emission in the super-Eddington state

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