{
  "id": "2304.06077",
  "version": "v1",
  "published": "2023-04-12T18:00:05.000Z",
  "updated": "2023-04-12T18:00:05.000Z",
  "title": "A journey from the hard to the soft state: How do QPOs evolve in the 2021 outburst of GX 339-4?",
  "authors": [
    "H. Stiele",
    "A. K. H. Kong"
  ],
  "comment": "6 pages, 5 figures, supplementary online material as appendices (13 pages), accepted for publication in MNRAS",
  "doi": "10.1093/mnras/stad969",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We investigated the snapshots of five NICER observations of the black hole transient GX 339-4 when the source transited from the hard state into the soft state during its outburst in 2021. In this paper, we focused our study on the evolution of quasi-periodic oscillations (QPOs) and noise components using power-density spectra. In addition, we derived hardness ratios comparing count rates above and below 2 keV. The evolution from the hard to the soft state was a somewhat erratic process showing several transitions between states that are dominated by top-flat noise and can show type-C QPOs; those that are dominated by red noise and can show type-B QPOs. From the parameters that we studied, we only found a strong correlation between the hardness ratio and the type of QPO observed. This implies that the appearance of type-B QPOs is related to a change in the accretion geometry of the system that also reflects in altered spectral properties. We also observed that the type-B QPO forms from or disintegrates into a broad peaked feature when the source comes out of or goes to the hard-intermediate state, respectively. This implies some strong decoherence in the process that creates this feature.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-04-12T18:00:05.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "soft state",
      "qpos evolve",
      "black hole transient gx",
      "type-b qpo forms",
      "somewhat erratic process"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}