Self-consistent Modeling of Reionization in Cosmological Hydrodynamical Simulations

Oñorbe, José; Hennawi, Joseph F.; Lukić, Zarija

doi:10.3847/1538-4357/aa6031

Cited by 124 publications

(211 citation statements)

References 152 publications

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“…In this section, we compare our new synthesis model with several integral constraints as well as to the previous FG09, HM12, and fiducial KS19 model (their Q18 model). In §3, we will also compare our new model to results from Oñorbe et al (2017) and Puchwein et al (2019) on modeling the effects of reionization. Figure 4 compares the frequency-resolved total UV emissivity at z 1.5 inferred by Chiang et al (2019) to the model emissivities for galaxies and AGN based on the assumptions detailed in §2.2-2.3.…”

Section: Integral Constraints and Synthesis Resultsmentioning

confidence: 99%

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A cosmic UV/X-ray background model update

Faucher-Giguère

2020

Monthly Notices of the Royal Astronomical Society

179

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We present an updated model of the cosmic ionizing background from the UV to the X-rays. Relative to our previous model ), the new model provides a better match to a large number of up-to-date empirical constraints, including: 1) new galaxy and AGN luminosity functions; 2) stellar spectra including binary stars; 3) obscured and unobscured AGN; 4) a measurement of the non-ionizing UV background; 5) measurements of the intergalactic HI and HeII photoionization rates at z ∼ 0 − 6; 6) the local X-ray background; and 7) improved measurements of the intergalactic opacity. In this model, AGN dominate the HI ionizing background at z 3 and star-forming galaxies dominate it at higher redshifts. Combined with the steeply declining AGN luminosity function beyond z ∼ 2, the slow evolution of the HI ionization rate inferred from the high-redshift HI Lyα forest requires an escape fraction from star-forming galaxies that increases with redshift (a population-averaged escape fraction of ≈ 1% suffices to ionize the intergalactic medium at z = 3 when including the contribution from AGN). We provide effective photoionization and photoheating rates calibrated to match the Planck 2018 reionization optical depth and recent constraints from the HeII Lyα forest in hydrodynamic simulations.

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Section: Integral Constraints and Synthesis Resultsmentioning

confidence: 99%

“…Recently, Oñorbe et al (2017) substantially developed the concepts of effective photoionization and photoheating rates and showed explicitly how to modify UVB models so that they produce a correct mean reionization history and . BPASS spectral templates for star-forming galaxies.…”

Section: Introductionmentioning

confidence: 99%

A cosmic UV/X-ray background model update

Faucher-Giguère

2020

Monthly Notices of the Royal Astronomical Society

179

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“…These lower redshift skewers are also re-scaled but to match the mean flux to be consistent with published measurements. We use the fitting formula presented in Oñorbe et al (2017a) For each skewer of the high redshift Lyβ forest, we now draw a random Lyα forest segment from a simulation output at the corresponding foreground redshift. In this way we ensure that we account for the full distribution of foreground Lyα opacities, and do not underestimate the scatter between different foreground sightlines.…”

Section: Calculating the Optical Depth From Simulated Skewersmentioning

confidence: 99%

Anomaly in the Opacity of the Post-reionization Intergalactic Medium in the Lyα and Lyβ Forest

Eilers

Davies

Oñorbe

2019

ApJ

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We measure the intergalactic medium (IGM) opacity in the Lyα as well as in the Lyβ forest along 19 quasar sightlines between 5.5 z abs 6.1, probing the end stages of the reionization epoch. Owing to its lower oscillator strength the Lyβ transition is sensitive to different gas temperatures and densities than Lyα, providing additional constraints on the ionization and thermal state of the IGM. A comparison of our measurements to different inhomogeneous reionization models, derived from post-processing the Nyx cosmological hydrodynamical simulation to include spatial fluctuations in the ultraviolet background (UVB) or the gas temperature field, as well as to a uniform reionization model with varying thermal states of the IGM, leads to two primary conclusions: First, we find that including the effects of spectral noise is key for a proper data to model comparison. Noise effectively reduces the sensitivity to high opacity regions, and thus even stronger spatial inhomogeneities are required to match the observed scatter in the observations than previously inferred. Second, we find that models which come close to reproducing the distribution of Lyα effective optical depths nevertheless underpredict the Lyβ opacity at the same spatial locations. The origin of this disagreement is not entirely clear but models with an inversion in the temperature-density relation of the IGM just after reionization is completed match our measurements best, although they still do not fully capture the observations at z 5.8.

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“…Ignoring spatial and temporal variations in the spectral shape of the ionizing photon emissivity, evaluating the integral in Equation (18) analytically for β = 2, and using the relation (e.g., Kohler et al 2007;Oñorbe et al 2017)…”

Section: Reionization Equation 41 Hydrogen Photoionization Ratementioning

confidence: 99%

Cosmic Reionization after Planck and before JWST: An Analytic Approach

Madau

2017

ApJ

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The reionization of cosmic hydrogen marks a critical juncture in the history of structure formation in the universe. Here we present a new formulation of the standard reionization equation for the time evolution of the volume-averaged H II fraction that is more consistent with the accepted conceptual model of inhomogeneous intergalactic absorption. The revised equation retains the basic terminology and simplicity of the classic calculation but explicitly accounts for the presence of the optically thick "Lyman-limit systems" that are known to determine the mean free path of ionizing radiation after overlap. Integration of the modified equation provides a better characterization of the timing of reionization by smoothly linking the pre-overlap with the post-overlap phases of such process. We confirm the validity of the quasi-instantaneous approximation as predictor of reionization completion/maintenance, and discuss new insights on the sources of cosmic reionization using the improved formalism. A constant emission rate into the intergalactic medium (IGM) of about 3 Lyman continuum (LyC) photons per atom per Gyr leads to a reionization history that is consistent with a number of observational constraints on the ionization state of the z = 5-9 universe and with the reduced Thomson scattering optical depth recently reported by the Planck Collaboration. While star-forming galaxies can dominate the reionization process if the luminosity-weighted fraction of LyC photons that escape into the IGM, f esc , exceeds 15% (for a faint magnitude cut-off of the galaxy UV luminosity function of M lim = −13 and a LyC photon yield per unit 1500Å luminosity of ξ ion = 10 25.3 erg −1 Hz), simple models where the product of the two unknowns f esc ξ ion is not evolving with redshift fail to reproduce the changing neutrality of the IGM observed at these epochs.

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Self-consistent Modeling of Reionization in Cosmological Hydrodynamical Simulations

Cited by 124 publications

References 152 publications

A cosmic UV/X-ray background model update

A cosmic UV/X-ray background model update

Anomaly in the Opacity of the Post-reionization Intergalactic Medium in the Lyα and Lyβ Forest

Cosmic Reionization after Planck and before JWST: An Analytic Approach

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