Reionization in Technicolor. Issue 2 (25th July 2018)

• Record Type: Journal Article
• Authors: Finlator, Kristian; Keating, Laura; Oppenheimer, Benjamin D; Davé, Romeel; Zackrisson, Erik
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 480:Issue 2(2018)
• Page Start: 2628
• Page End: 2649
• Publication Date: 2018-07-25
• Subjects: galaxies: evolution -- galaxies: formation -- galaxies: high-redshift -- intergalactic medium -- quasars: absorption lines -- dark ages, reionization, first stars; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty1949
• Languages: English
• ISSNs: 0035-8711

Abstract

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 10 8 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 f esc, 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 $\mathrm{Si\, {\small IV}}$ column density distribution is reasonably well reproduced (∼1σ low). By contrast, $\mathrm{C\, {\small IV}}$ 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.