{
  "id": "1607.02664",
  "version": "v1",
  "published": "2016-07-09T21:08:04.000Z",
  "updated": "2016-07-09T21:08:04.000Z",
  "title": "X-ray Background at High Redshifts from Pop III Remnants: Results from Pop III star formation rates in the Renaissance Simulations",
  "authors": [
    "Hao Xu",
    "Kyungjin Ahn",
    "Michael L Norman",
    "John H Wise",
    "Brian W O'Shea"
  ],
  "comment": "5 pages, 5 figures, submitted to Astrophysical Journal Letters",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "Due to their long mean free paths, X-rays are expected to have many significant impacts globally on the properties of the intergalactic medium (IGM) by their heating and ionizing processes on large scales. At high redshifts, X-rays from Population (Pop) III binaries might have important effects on cosmic reionization and the Lyman alpha forest. As a continuation of our previous work on Pop III binary X-rays (Xu et al. 2014), we use the Pop III distribution and evolution from the Renaissance Simulations, a suite of self-consistent cosmological radiation hydrodynamics simulations of the formation of the first galaxies, to calculate the X-ray luminosity density and background over the redshift range 20 > z > 7.6. As we find that Pop III star formation continues at a low, nearly constant rate to the end of reionization, X-rays are being continuously produced at significant rates compared to other possible X-ray sources, such as AGNs and normal X-ray binaries during the same period of time. We estimate that Pop III binaries produce approximately 6 eV of energy in the X-rays per hydrogen atom. We calculate the X-ray background for different monochromatic photon energies. KeV X-rays redshift and accumulate to produce a strong X-ray background spectrum extending to roughly 500 eV. The X-ray background is strong enough to heat the IGM to ~ 1000 K and to ionize a few percent of the neutral hydrogen. These effects are important for an understanding of the neutral hydrogen hyperfine transition 21-cm line signatures, the Ly alpha forest, and optical depth of the CMB to Thomson scattering.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-07-09T21:08:04.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "star formation rates",
      "high redshifts",
      "renaissance simulations",
      "cosmological radiation hydrodynamics simulations",
      "x-ray background spectrum extending"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}