{
  "id": "2104.08168",
  "version": "v1",
  "published": "2021-04-16T15:27:26.000Z",
  "updated": "2021-04-16T15:27:26.000Z",
  "title": "Probing Cosmic Dawn : Ages and Star Formation Histories of Candidate $z\\geq$9 Galaxies",
  "authors": [
    "N. Laporte",
    "R. A. Meyer",
    "R. S. Ellis",
    "B. E. Robertson",
    "J. Chisholm",
    "G. W. Roberts-Borsani"
  ],
  "comment": "12 pages, 12 figures, accepted for publication in MNRAS",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We discuss the spectral energy distributions and physical properties of six galaxies whose photometric redshifts suggest they lie beyond a redshift $z\\simeq$9. Each was selected on account of a prominent excess seen in the Spitzer/IRAC 4.5$\\mu$m band which, for a redshift above $z=9.0$, likely indicates the presence of a rest-frame Balmer break and a stellar component that formed earlier than a redshift $z\\simeq10$. In addition to constraining the earlier star formation activity on the basis of fits using stellar population models with BAGPIPES, we have undertaken the necessary, but challenging, follow-up spectroscopy for each candidate using various combinations of Keck/MOSFIRE, VLT/X-shooter, Gemini/FLAMINGOS2 and ALMA. Based on either Lyman-$\\alpha$ or [OIII] 88 $\\mu$m emission, we determine a convincing redshift of $z$=8.78 for GN-z-10-3 and a likely redshift of $z$=9.28 for the lensed galaxy MACS0416-JD. For GN-z9-1, we conclude the case remains promising for a source beyond $z\\simeq$9. Together with earlier spectroscopic data for MACS1149-JD1, our analysis of this enlarged sample provides further support for a cosmic star formation history extending beyond redshifts $z\\simeq$10. We use our best-fit stellar population models to reconstruct the past rest-frame UV luminosities of our sources and discuss the implications for tracing earlier progenitors of such systems with the James Webb Space Telescope.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-04-16T15:27:26.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "probing cosmic dawn",
      "star formation history extending",
      "earlier star formation activity",
      "cosmic star formation history",
      "james webb space telescope"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}