{
  "id": "2209.06662",
  "version": "v1",
  "published": "2022-09-14T14:16:42.000Z",
  "updated": "2022-09-14T14:16:42.000Z",
  "title": "Detection of a quasi-periodic oscillation at $\\sim$40 mHz in Cen X-3 with Insight-HXMT",
  "authors": [
    "Q. Liu",
    "W. Wang",
    "X. Chen",
    "W. Yang",
    "F. J. Lu",
    "L. M. Song",
    "J. L. Qu",
    "S. Zhang",
    "S. N. Zhang"
  ],
  "comment": "9 pages, MNRAS in press",
  "categories": [
    "astro-ph.HE",
    "astro-ph.SR"
  ],
  "abstract": "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 $\\sim$40 mHz with an averaged fractional rms amplitude of $\\sim9\\%$. We study the mHz QPO frequency and rms amplitude over orbital phases, and find that the QPO frequency is $\\sim$33-39 mHz at the orbital phase of 0.1-0.4, increasing to $\\sim$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 $\\sim 20$ ms (a hard lag) in the range of $\\sim$5-10 keV, and becomes negative (time lag of $-(20-70)$ ms) above $\\sim 10$ 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 disk is truncated near the corotation radius.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-09-14T14:16:42.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "quasi-periodic oscillation",
      "orbital phase",
      "insight-hxmt",
      "energy-dependent qpo analysis",
      "qpo time-lag analysis"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 9,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}