{
  "id": "2410.22250",
  "version": "v1",
  "published": "2024-10-29T17:15:18.000Z",
  "updated": "2024-10-29T17:15:18.000Z",
  "title": "The realm of Aurora. Density distribution of metal-poor giants in the heart of the Galaxy",
  "authors": [
    "Evgeny P. Kurbatov",
    "Vasily Belokurov",
    "Sergey Koposov",
    "Andrey Kravtsov",
    "Elliot Y. Davies",
    "Anthony G. A. Brown",
    "Tristan Cantat-Gaudin",
    "Alfred Castro-Ginard",
    "Andrew R. Casey",
    "Ronald Drimmel",
    "Morgan Fouesneau",
    "Shourya Khanna",
    "Hans-Walter Rix",
    "Alex Wallace"
  ],
  "comment": "Submitted to MNRAS",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "The innermost portions of the Milky Way's stellar halo have avoided scrutiny until recently. The lack of wide-area survey data, made it difficult to reconstruct an uninterrupted view of the density distribution of the metal-poor stars inside the Solar radius. In this study, we utilize red giant branch (RGB) stars from Gaia, with metallicities estimated using spectro-photometry from Gaia Data Release 3. Accounting for Gaia's selection function, we examine the spatial distribution of metal-poor ([M/H]<-1.3) RGB stars, from the Galactic centre (r~1 kpc) out to beyond the Solar radius (r~18 kpc). Our best-fitting single-component cored power-law model shows a vertical flattening of ~0.5 and a slope -3.4, consistent with previous studies. Motivated by the mounting evidence for two distinct stellar populations in the inner halo, we additionally test a range of two-component models. One of the components models the tidal debris from the Gaia Sausage/Enceladus merger, while the other captures the Aurora population -- stars that predate the Galactic disk formation. Our best-fit two-component model suggests that both populations contribute equally around the Solar radius, but Aurora dominates the inner halo with a steeper power-law index of -4.5, in agreement with the nitrogen-rich star distribution measured by Horta et al. (2021).",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-10-29T17:15:18.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "density distribution",
      "metal-poor giants",
      "solar radius",
      "two-component model",
      "inner halo"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}