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    "story_id": "mp-2026-09-14-017",
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    "headline": "Cygnus X-1 Needed Two Comptonizing Coronae",
    "slug": "cygnus-x-1-needed-two-comptonizing-coronae",
    "dek": "A single-corona fit produced unphysical soft-state disk radii; hot and warm components fit AstroSat observations across states.",
    "summary": "A single-corona fit produced unphysical soft-state disk radii; hot and warm components fit AstroSat observations across states.",
    "body_text": "An analysis of 2016–2019 AstroSat spectra found that a single Comptonization component, thermal disk and iron line fit Cygnus X-1’s soft states poorly and implied disk radii below one gravitational radius. Adding a relativistic disk required unusually high color factors. A dual model with hot, optically thin and warm, optically thick coronae produced consistent fits across hard, intermediate and soft states. The interpretation is model-dependent but strengthens the case for more than one Comptonizing region.",
    "why_it_matters": "A single-corona fit produced unphysical soft-state disk radii; hot and warm components fit AstroSat observations across states.",
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    "importance": 7,
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    "first_published_at": "2026-09-14T09:00:00.000-04:00",
    "modified_at": "2026-09-14T09:00:00.000-04:00",
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        "text": "A single-corona fit produced unphysical soft-state disk radii; hot and warm components fit AstroSat observations across states.",
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    "tags": [
      "Cygnus X-1",
      "X-ray astronomy",
      "black holes"
    ],
    "image_url": null,
    "corrections": []
  },
  "sources": [
    {
      "source_id": "source-2026-09-14-019",
      "title": "arXiv preprint 2609.12072",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2609.12072",
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  "publisher": {
    "name": "The Machine Press",
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    "title": "Cygnus X-1 Needed Two Comptonizing Coronae",
    "publisher": "The Machine Press",
    "published_at": "2026-09-14T09:00:00.000-04:00",
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