{
  "id": "2307.13979",
  "version": "v1",
  "published": "2023-07-26T06:35:58.000Z",
  "updated": "2023-07-26T06:35:58.000Z",
  "title": "$AstroSat$ view of the neutron star low-mass X-ray binary GX 340+0",
  "authors": [
    "Yash Bhargava",
    "Sudip Bhattacharyya",
    "Jeroen Homan",
    "Mayukh Pahari"
  ],
  "comment": "7 figures, 1 table. Accepted for publication in ApJ",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Understanding the spectral evolution along the `Z'-shaped track in the hardness-intensity diagram of Z-sources, which are a class of luminous neutron star low-mass X-ray binaries, is crucial to probe accretion processes close to the neutron star. Here, we study the horizontal branch (HB) and the normal branch (NB) of the Z source GX 340+0 using $AstroSat$ data. We find that the HB and the NB appear as two different types of X-ray intensity dips, which can appear in any sequence and with various depths. Our $0.8-25$~keV spectra of dips and the hard apex can be modeled by the emissions from an accretion disk, a Comptonizing corona covering the inner disk, and the neutron star surface. We find, as the source moves onto the HB the corona is replenished and energized by the disk and a reduced amount of disk matter reaches the neutron star surface. We also conclude that quasi-periodic oscillations during HB/NB are strongly associated with the corona, and explain the evolution of strength and hard-lag of this timing feature using the estimated coronal optical depth evolution.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-07-26T06:35:58.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "neutron star low-mass x-ray binary",
      "star low-mass x-ray binary gx",
      "coronal optical depth evolution",
      "neutron star surface"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}