Accretion torque reversals in GRO J1008-57 revealed by Insight-HXMT

Wang, W.; Tang, Yaming; Tuo, You-Li; Epili, Prahlad; Zhang, S.N.; Song, Liming; Lu, F. J.; Qu, J. L.; Ge, Ming-Yu; Huang, Y.; Li, B.; Bu, Q. C.; Cai, C.; Cao, X. L.; Chang, Zhi; Chen, L.; Chen, T.X.; Chen, Y.B.; Chen, Y.; Cui, Wei; Du, Y. Y.; Gao, G. H.; Gu, Y. D.; Guan, J.; Guo, Chengcheng; Han, Danxiang; Jia, Haiqiang; Jia, S. M.; Jiang, Weichun; Jin, J.; Kong, L. D.; Li, C.K.; Li, G.; Li, T.P.; Li, W.; Li, X.; Li, Z.W.; Liang, X. H.; Liao, J. Y.; Liu, B.S.; Liu, C.Z.; Liu, H.X.; Lu, X. F.; Luo, Q.; Luo, T.; Ma, Ruican; Ma, Xiang; Meng, Bin; Nang, Y.; Nie, J. Y.; Ou, G.; Ren, Xiaokang; Sai, N.; Song, X. Y.; Sun, Liang; Tao, Lian; Wang, C.; Wang, L.J.; Wang, P.J.; Wang, Wangsheng; Wang, Y.S.; Wen, Xiang-Yang; Wu, Bai-Yang; Wu, Mei‐Hwan; Xiao, G. C.; Xiao, Shuo; Xiong, S. L.; Yang, Rong-Jia; Yang, S.; Yang, Jiawei; Yang, Yi-Jung; Yi, B. B.; Yin, Q. Q.; You, Y.; Zhang, F.; Zhang, H.M.; Zhang, Ji Ping; Zhang, P.; Zhang, W.; Zhang, Y.F.; Zhao, H. S.; Zhao, Xiaofan; Zheng, S.; Zheng, Y. G.; Zhou, D. K.

doi:10.1016/j.jheap.2021.01.002

Cited by 16 publications

(5 citation statements)

References 28 publications

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“…For this source, there are different detections of CRSFs in the energy range 78−90 keV, which correspond to a magnetic field of about 7 − 8 × 10 12 G (Grove et al 1995;Bellm et al 2014;Ge et al 2020). Correlations between the X-ray luminosity and the spin period derivative strongly suggest the presence of an accretion disc around GRO J1008−57 during the X-ray outbursts (see, e.g., Wang et al 2021). The distance of the system is either 9.7 ± 0.8 kpc or 5.8 ± 0.5 kpc (Riquelme et al 2012).…”

Section: A0535+26mentioning

confidence: 92%

Modelling the expected very high energy γ-ray emission from accreting neutron stars in X-ray binaries

Ducci,

Romano,

Vercellone

et al. 2023

Monthly Notices of the Royal Astronomical Society

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The detection of γ −ray emission from accreting pulsars in X-ray binaries (XRBs) has long been sought after. For some high-mass X-ray binaries (HMXBs), marginal detections have recently been reported. Regardless of whether these will be confirmed or not, future telescopes operating in the γ −ray band could offer the sensitivity needed to achieve solid detections and possibly spectra. In view of future observational advances, we explored the expected emission above 10 GeV from XRBs, based on the Cheng & Ruderman model, where γ −ray photons are produced by the decay of π0 originated by protons accelerated in the magnetosphere of an accreting pulsar fed by an accretion disc. We improved this model by considering, through Monte Carlo simulations, the development of cascades inside of and outside the accretion disc, taking into account pair and photon production processes that involve interaction with nuclei, X-ray photons from the accretion disc, and the magnetic field. We produced grids of solutions for different input parameter values of the X-ray luminosity (Lx), magnetic field strength (B), and for different properties of the region where acceleration occurs. We found that the γ −ray luminosity spans more than five orders of magnitude, with a maximum of ∼1035 erg s−1. The γ −ray spectra show a large variety of shapes: some have most of the emission below ∼100 GeV, others are harder (emission up to 10−100 TeV). We compared our results with Fermi/LAT and VERITAS detections and upper-limits of two HMXBs: A0535+26 and GRO J1008−57. More consequential comparisons will be possible when more sensitive instruments will be operational in the coming years.

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Section: A0535+26mentioning

confidence: 92%

Modelling the expected very high energy γ-ray emission from accreting neutron stars in X-ray binaries

Ducci,

Romano,

Vercellone

et al. 2023

Monthly Notices of the Royal Astronomical Society

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“…The specifications related to the Insight-HXMT observations under consideration are presented in Table 1. The Insight-HXMT Data Analysis Software (HXMTDAS) v2.04 is used to analyze data (more details on the analysis have been introduced in previous publications, e.g., Wang et al 2021;Chen et al 2021). In order to take advantage of the bestscreened event file to generate the high-level products, including the energy spectra, response file, light curves, and background files, we use the tasks he/me/lepical to remove spike events caused by electronic systems and he/me/ legtigen to select good time intervals when the pointing offset angle is <0°.04, the pointing direction above Earth is >10°, the geomagnetic cutoff rigidity is >8 GeV, and the South Atlantic Anomaly had not occurred within 300 s. We also utilize the FTOOL grppha to improve the counting statistic of the spectrum.…”

Section: Observationsmentioning

confidence: 99%

Evidence for a Cyclotron Absorption Line and Spectral Transition in EXO 2030+375 during the 2021 Giant Outburst

Yang,

Wang,

Epili

2024

ApJ

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Based on Insight-HXMT observations of EXO 2030+375 during its 2021 giant outburst, we report the analysis of pulse variations and the broadband X-ray spectrum, and find the presence of a potential cyclotron resonant scattering feature (CRSF) with the fundamental line at ∼47 keV from both average spectra and phase-resolved spectroscopy. During the outburst, the source reached an X-ray luminosity of ∼1038 erg s−1 from 2 to 105 keV at a distance of 7.1 kpc. The X-ray pulsar at the spin period of 41.27 ± 0.61 s exhibits complex timing and spectral variations with both energy and luminosity during the outburst. The shapes of the pulse profiles show the single main peak above ∼20 keV, while appearing to exhibit multipeak patterns in low-energy bands, and the transition of the 10–20 keV pulse profiles from multipeak to single peak is observed at ∼0.8 × 1038 erg s−1, which suggests the evolution from the subcritical luminosity (pencil-beam dominated) to the supercritical luminosity (fan-beam dominated) regime. A dip structure before the energy of the CRSFs is found in the pulse fraction–energy relation of EXO 2030+375 near the peak luminosity. A detailed analysis of spectral parameters showed that the power-law photon index exhibits three distinct trends as luminosity increases, and these spectral changes also signify a spectral transition from subcritical to supercritical regimes. The critical luminosity infers a magnetic field of ∼(4.8−6.0) × 1012 G, which supports the presence of the cyclotron line at ∼47 keV. A Comptonization model applied for the broad X-ray spectra during the outburst also suggests the surface magnetic field ranging from ∼(5−9) × 1012 G.

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“…The energy resolved pulse profiles were finally created by folding the light curves in different energy bands with the obtained pulse period for each exposure ID. The pulse profile for the accreting pulsar is usually highly energy dependent (Li et al 2012;Ding et al 2021;Wang et al 2021). As an example of Vela X-1, Fig.…”

Section: Timing Analysismentioning

confidence: 99%

Variations of cyclotron resonant scattering features in Vela X-1 revealed with Insight-HXMT

Liu,

Wang,

Chen

et al. 2022

Preprint

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We present a detailed study of the high mass X-ray binary Vela X-1, using observations performed by Insight-HXMT in 2019 and 2020, concentrating on timing analysis and spectral studies including pulse phase-resolved spectroscopy. The cyclotron line energy is found to be at ∼ 21 − 27 keV and 43 − 50 keV for the fundamental and first harmonic, respectively. We present the evolution of spectral parameters and find that two line centroid energy ratio 2 / 1 evolved from ∼ 2 before MJD 58900 to ∼ 1.7 after that. The harmonic cyclotron line energy has no relation to the luminosity but the fundamental line energy shows a positive correlation with X-ray luminosity, suggesting that Vela X-1 is located in the sub-critical accreting regime. In addition, the pulse phase-resolved spectroscopy in Vela X-1 is performed. Both the CRSF and continuum parameters show strong variability over the pulse phase with the ratio of two line energies about 2 near the peak phases, and down to ∼ 1.6 around off-peak phases. Long-term significant variations of the absorption column density and its evolution over the pulse phase may imply the existence of the clumpy wind structure near the neutron star.

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Accretion torque reversals in GRO J1008-57 revealed by Insight-HXMT

Cited by 16 publications

References 28 publications

Modelling the expected very high energy γ-ray emission from accreting neutron stars in X-ray binaries

Modelling the expected very high energy γ-ray emission from accreting neutron stars in X-ray binaries

Evidence for a Cyclotron Absorption Line and Spectral Transition in EXO 2030+375 during the 2021 Giant Outburst

Variations of cyclotron resonant scattering features in Vela X-1 revealed with Insight-HXMT

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