Detection of a quasi-periodic oscillation at ∼40 mHz in Cen X-3 with Insight-HXMT
Sep 14, 20229 pages
Published in:
- Mon.Not.Roy.Astron.Soc. 516 (2022) 4, 5579-5587
- Published: Oct 4, 2022
e-Print:
- 2209.06662 [astro-ph.HE]
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Abstract: (Oxford University Press)
We investigated the quasi-periodic oscillation (QPO) features in the accretion-powered X-ray pulsar Cen X-3 observed by Insight-HXMT. For two observations in 2020 when Cen X-3 was in an extremely soft state, the power density spectrum revealed the presence of obvious QPO features at ∼40 mHz with an averaged fractional rms amplitude of ∼9 per cent. We study the mHz QPO frequency and rms amplitude over orbital phases, and find that the QPO frequency is ∼33–39 mHz at the orbital phase of 0.1–0.4, increasing to ∼37–43 mHz in the orbital phase of 0.4–0.8, but has no strong dependence on X-ray intensity. We also carried out an energy-dependent QPO analysis, the rms amplitude of the mHz QPOs have a decreasing trend as the energy increases from 2 to 20 keV. In addition, the QPO time-lag analysis shows that the time-delay is ∼20 ms (a hard lag) in the range of ∼5–10 keV, and becomes negative [time-lag of −(20–70) ms] above ∼10 keV. The different QPO theoretical models are summarized and discussed. In the end, we suggest that these energy-dependent timing features as well as the origin of mHz QPOs in Cen X-3 may be ascribed to an instability when the accretion disc is truncated near the corotation radius.Note:
- 9 pages, MNRAS in press
- stars: neutron
- pulsars: individual: Cen X-3
- X-rays: binaries
References(101)
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