Large scale simulations of H and He reionization and heating driven by stars and more energetic sources

Abstract

We present simulations of cosmic reionization and reheating from $z=18$ to $z=5$, investigating the role of stars (emitting soft UV-photons), nuclear black holes (BHs, with power-law spectra), X-ray binaries (XRBs, with hard X-ray dominated spectra), and the supernova-associated thermal bremsstrahlung of the diffuse interstellar medium (ISM, with soft X-ray spectra). We post-process the hydrodynamical simulation Massive-Black II (MBII) with multifrequency ionizing radiative transfer. The source properties are directly derived from the physical environment of MBII, and our only real free parameter is the ionizing escape fraction $f_{\mathrm{esc}}$. We find that, among the models explored here, the one with an escape fraction that decreases with decreasing redshift yields results most in line with observations, such as of the neutral hydrogen fraction and the Thomson scattering optical depth. Stars are the main driver of hydrogen reionization and consequently of the thermal history of the intergalactic medium (IGM). We obtain $⟨x_{\mathrm{HII}}⟩=0.99998$ at $z=6$ for all source types, with volume averaged temperatures $⟨T⟩\sim 20,000\mathrm{K}$. BHs are rare and negligible to hydrogen reionization, but conversely they are the only sources which can fully ionize helium, increasing local temperatures by $\sim 10^4\mathrm{K}$. The thermal and ionization state of the neutral and lowly ionized hydrogen differs significantly with different source combinations, with ISM and (to a lesser extent) XRBs, playing a significant role and, as a consequence, determining the transition from absorption to emission of the 21 cm signal from neutral hydrogen.

17 pages, 19 figures, accepted for publication in MNRAS

References in corpus (36)

• The NumPy array: a structure for efficient numerical computation
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• Direct cosmological simulations of the growth of black holes and galaxies
• Model-independent evidence in favor of an end to reionization by z~6
• Efficient Simulations of Early Structure Formation and Reionization
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization
• The morphology of HII regions during reionization
• Faint AGNs at z>4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium
• HeII Reionization and its Effect on the IGM
• Inferences on the Timeline of Reionization at z~8 From the KMOS Lens-Amplified Spectroscopic Survey
• Radiative transfer simulations of cosmic reionization I: methodology and initial results
• The First Billion Years Project: The escape fraction of ionizing photons in the epoch of reionization
• Inside-out or Outside-in: The topology of reionization in the photon-starved regime suggested by Lyman-alpha forest data
• Mean Spectral Energy Distributions and Bolometric Corrections for Luminous Quasars
• Cosmic Reionization On Computers I. Design and Calibration of Simulations
• Understanding the escape of LyC and Ly$\alpha$ photons from turbulent clouds
• Constraining the intergalactic medium at $z\approx$ 9.1 using LOFAR Epoch of Reionization observations
• Fast Large-Scale Reionization Simulations
• Glimpsing through the high redshift neutral hydrogen fog
• CRASH2: colored packets and other updates
• Observations of the Lyman series forest towards the redshift 7.1 quasar ULAS J1120+0641
• Cosmic Reionization After Planck and Before JWST: An Analytic Approach
• Testing Reionization with Gamma Ray Burst Absorption Spectra
• Simulating Star Clusters Across Cosmic Time: II. Escape Fraction of Ionizing Photons from Molecular Clouds
• Epoch of Reionisation 21cm Forecasting From MCMC-Constrained Semi-Numerical Models
• The Impact of Unresolved Turbulence on the Escape Fraction of Lyman Continuum Photons
• Predictions for the 21cm-galaxy cross-power spectrum observable with SKA and future galaxy surveys
• Probing the high-z IGM with the hyperfine transition of ${}^3$He${}^{+}$
• Observing the redshifted 21 cm signal around a bright QSO at $z\sim 10$
• Galactic wind X-ray heating of the intergalactic medium during the Epoch of Reionization
• Enabling Radiative Transfer on AMR grids in CRASH