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Reionization in technicolor

Research output: Contribution to journalArticle

  • Kristian Finlator
  • Laura Keating
  • Benjamin D. Oppenheimer
  • Romeel Davé
  • Erik Zackrisson

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Original languageEnglish
Pages (from-to)2628-2649
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Volume480
Issue number2
Early online date25 Jul 2018
DOIs
Publication statusPublished - 1 Oct 2018

Abstract

We present the Technicolor Dawn simulations, a suite of cosmological radiation hydrodynamic simulations of the first 1.2 billion yr. By modelling a spatially inhomogeneous ultraviolet background (UVB) on the fly with 24 frequencies and resolving dark matter haloes down to 108 M⊙ within 12 h-1 Mpc volumes, our simulations unify observations of the intergalactic and circumgalactic media, galaxies, and reionization into a common framework. The only empirically tuned parameter, the fraction fesc, gal(z) of ionizing photons that escape the interstellar medium, is adjusted to match observations of the Lyman-α forest and the cosmic microwave background. With this single calibration, our simulations reproduce the history of reionization; the stellar mass and star formation rate relation of galaxies; the number density and metallicity of damped Lyman-α absorbers (DLAs) at z ~ 5; the abundance of weak metal absorbers; the ultraviolet background amplitude; and the Lyman-α flux power spectrum at z = 5.4. The galaxy stellar mass and ultraviolet luminosity functions are underproduced by ≤ 2 ×, suggesting an overly vigorous feedback model. The mean transmission in the Lyman-α forest is underproduced at z < 6, indicating tension between measurements of the UVB amplitude and Lyman-α transmission. The observed Si IV column density distribution is reasonably well reproduced (~1σ low). By contrast, CIV remains significantly underproduced despite being boosted by an intense > 4 Ryd UVB. Solving this problem by increasing metal yields would overproduce both weak absorbers and DLA metallicities. Instead, the observed strength of high-ionization emission from high-redshift galaxies and absorption from their environments suggest that the ionizing flux from conventional stellar population models is too soft.

    Research areas

  • Dark ages, First stars, Galaxies: evolution, Galaxies: formation, Galaxies: high-redshift, Intergalactic medium, Quasars: absorption lines, Reionization

ID: 76908208