{
  "id": "2205.12271",
  "version": "v1",
  "published": "2022-05-24T18:00:00.000Z",
  "updated": "2022-05-24T18:00:00.000Z",
  "title": "Information content of BP/RP spectra in Gaia DR3",
  "authors": [
    "Callum E. C. Witten",
    "David S. Aguado",
    "Jason L. Sanders",
    "Vasily Belokurov",
    "N. Wyn Evans",
    "Sergey E. Koposov",
    "Carlos Allende Prieto",
    "Francesca De Angeli",
    "Mike J. Irwin"
  ],
  "comment": "12 pages, 10 figures, 1 table. Submitted to MNRAS. Comments are welcome",
  "categories": [
    "astro-ph.SR",
    "astro-ph.GA"
  ],
  "abstract": "Gaia Data Release 3 will provide the astronomical community with the largest stellar spectroscopic survey to date ($>$ 100 million sources). The low resolution (R$\\sim$50) blue photometer (BP) and red photometer (RP) spectra will allow for the estimation of stellar parameters such as effective temperature, surface gravity and metallicity. We create mock Gaia BP/RP spectra and use Fisher information matrices to probe the resolution limit of stellar parameter measurements using BP/RP spectra. The best-case scenario uncertainties that this analysis provides are then used to produce a mock observed stellar population in order to probe the false positive rate (FPR) of identifying extremely metal-poor (EMP) stars. We find that we can confidently identify metal-poor stars at magnitudes brighter than $G = 16$. At fainter magnitudes true detections start to be overwhelmed by false positives. When adopting the commonly-used $G < 14$ magnitude limit for metal-poor star searches, we find a FPR for the low-metallicity regimes [Fe/H] < -2, -2.5 and -3 of just 14$\\%$, 33$\\%$ and 56$\\%$ respectively, offering the potential for a significant improvement on previous targeting campaigns. Additionally, we explore the chemical sensitivity obtainable directly from BP/RP spectra for Carbon and $\\alpha$-elements. We find an absolute Carbon abundance uncertainty of $\\sigma_{A(C)} < 1$ dex for Carbon-enriched metal-poor (CEMP) stars, indicating the potential to identify a CEMP stellar population for follow-up confirmation with higher resolution spectroscopy. Finally, we find that large uncertainties in $\\alpha$-element abundance measurements using Gaia BP/RP spectra means that efficiently obtaining these abundances will be challenging.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-05-24T18:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "information content",
      "gaia dr3",
      "fainter magnitudes true detections start",
      "create mock gaia bp/rp spectra",
      "largest stellar spectroscopic survey"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}