{
  "abstract": "Context. Swift J1727.8-1613 is an X-ray binary observed during its 2023-2024 outburst, including bright and dim hard states with similar X-ray polarimetric signatures but fluxes differing by two orders of magnitude. Aims. We aim to reproduce the spectro-polarimetric properties of these two hard states. Methods. We modelled their spectra in the JED-SAD framework and computed the X-ray polarisation properties of the best-fit configurations with the MONK general relativistic radiative transfer code. Results. Both spectra are well reproduced within the JED-SAD framework, although the dominant radiative process differs: self-Comptonised bremsstrahlung in the bright state and self-Comptonised synchrotron in the dim state. In the bright state, the simulated polarisation fraction remains below the observed value of about 4%, while the polarisation angle differs from the observations by 90 degrees because of the JED's large vertical optical depth. In contrast, the dim state's simulated polarisation fraction is about 3% and its polarisation angle is perpendicular to the disk, both broadly consistent with IXPE measurements. The dim-state results are largely insensitive to the magnetic field configuration because of Faraday depolarisation. Conclusions. The dim hard state's spectro-polarimetric properties are well reproduced, whereas those of the bright state are not. We discuss a non-thermal particle distribution and electron scattering in an accretion-disk wind as possible explanations for the observed bright-state polarisation.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.15301",
  "author_total": 13,
  "authors": [
    {
      "name": "R Muhammad"
    },
    {
      "name": "P.-O Petrucci"
    },
    {
      "name": "W Zhang"
    },
    {
      "name": "J Ferreira"
    },
    {
      "name": "R Belmont"
    },
    {
      "name": "J Malzac"
    },
    {
      "name": "G Marcel"
    },
    {
      "name": "G Matt"
    },
    {
      "name": "M Parra"
    },
    {
      "name": "T Bouchet"
    },
    {
      "name": "N Barnier"
    },
    {
      "name": "M Clavel"
    },
    {
      "name": "G Henri"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/80bm0ngak7hm5.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.15301",
  "fulltext_url": null,
  "id": "80bm0ngak7hm5",
  "issns": [],
  "landing_url": "https://hal.science/hal-05782749v1",
  "language": "en",
  "licence": "CC0-1.0",
  "licence_label": "CC0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/publicdomain/zero/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "hal",
      "0.phys"
    ],
    [
      "hal",
      "1.phys.astr"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.15301",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-14",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/80bm0ngak7hm5.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:50Z",
      "native_id": "hal-05782749",
      "source": "hal",
      "url": "https://hal.science/hal-05782749v1"
    },
    {
      "first_seen": "2026-10-30T12:21:25Z",
      "native_id": "2609.15301",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.15301"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "hal:0.phys",
      "subfield": "general"
    }
  ],
  "title": "Spectro-polarimetric study of the black hole X-ray binary Swift J1727.8-1613 in the JED-SAD framework",
  "title_text": "Spectro-polarimetric study of the black hole X-ray binary Swift J1727.8-1613 in the JED-SAD framework",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:25Z",
  "url": "https://research.draconitic.com/paper/80bm0ngak7hm5",
  "venue": "HAL",
  "versions": []
}