{
  "id": "2401.03289",
  "version": "v1",
  "published": "2024-01-06T19:56:15.000Z",
  "updated": "2024-01-06T19:56:15.000Z",
  "title": "NuSTAR and Swift observations of two supergiant fast X-ray transients: AX J1841.0-0536 and SAX J1818.6-1703",
  "authors": [
    "E. Bozzo",
    "C. Ferrigno",
    "P. Romano"
  ],
  "comment": "Accepted for publication on MNRAS",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Supergiant fast X-ray transients are wind-fed binaries hosting neutron star accretors, which display a peculiar variability in the X-ray domain. Different models have been proposed to explain this variability and the strength of the compact object magnetic field is generally considered a key parameter to discriminate among possible scenarios. We present here the analysis of two simultaneous observational campaigns carried out with Swift and NuSTAR targeting the supergiant fast X-ray transient sources AX J1841.0-0536 and SAX J1818.6-1703. A detailed spectral analysis is presented for both sources, with the main goal of hunting for cyclotron resonant scattering features that can provide a direct measurement of the neutron star magnetic field intensity. AX J1841.0-0536 was caught during the observational campaign at a relatively low flux. The source broad-band spectrum was featureless and could be well described by using a combination of a hot blackbody and a power-law component with no measurable cut-off energy. In the case of SAX J1818.6-1703, the broad-band spectrum presented a relatively complex curvature which could be described by an absorbed cut-off power-law (including both a cut-off and a folding energy) and featured a prominent edge at $\\sim$7 keV, compatible with being associated to the presence of a \"screen\" of neutral material partly obscuring the X-ray source. The fit to the broad-band spectrum also required the addition of a moderately broad ($\\sim$1.6 keV) feature centered at $\\sim$14 keV. If interpreted as a cyclotron resonant scattering feature, our results would indicate for SAX J1818.6-1703 a relatively low magnetized neutron star ($\\sim$1.2$\\times$10$^{12}$ G).",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-01-06T19:56:15.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "supergiant fast x-ray transient",
      "sax j1818",
      "x-ray transient sources ax",
      "swift observations",
      "fast x-ray transient sources"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}