Galactic ionising photon budget during the Epoch of Reionisation in the Cosmic Dawn II simulation

Abstract

Cosmic Dawn ("CoDa") II yields the first statistically-meaningful determination of the relative contribution to reionization by galaxies of different halo mass, from a fully-coupled radiation-hydrodynamics simulation of the epoch of reionization large enough ($\sim$ 100 Mpc) to model global reionization while resolving the formation of all galactic halos above $\sim 10^8{M}_{\odot }$. Cell transmission inside high-mass haloes is bi-modal -- ionized cells are transparent, while neutral cells absorb the photons their stars produce - and the halo escape fraction $f_{esc}$ reflects the balance of star formation rate ("SFR") between these modes. The latter is increasingly prevalent at higher halo mass, driving down $f_{esc}$ (we provide analytical fits to our results), whereas halo escape luminosity, proportional to $f_{esc}\times$SFR, increases with mass. Haloes with dark matter masses within $6.10^8{M}_{\odot }<M_h<3.10^{10}{M}_{\odot }$ produce $\sim 80$% of the escaping photons at z=7, when the Universe is 50% ionized, making them the main drivers of cosmic reionization. Less massive haloes, though more numerous, have low SFRs and contribute less than 10% of the photon budget then, despite their high $f_{esc}$. High mass haloes are too few and too opaque, contributing $<10$% despite their high SFRs. The dominant mass range is lower (higher) at higher (lower) redshift, as mass function and reionization advance together (e.g. at z$=8.5$, x${}_{\mathrm{HI}}=0.9$, $M_h<5.10^9{M}_{\odot }$ haloes contributed $\sim$80%). Galaxies with UV magnitudes $M_{AB1600}$ between $-12$ and $-19$ dominated reionization between z$=6$ and 8.

Submitted to MNRAS on 09/01/2020. Accepted on 12/06/2020

References in corpus (16)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• The NumPy array: a structure for efficient numerical computation
• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• Escape fraction of ionizing photons during reionization: effects due to supernova feedback and runaway OB stars
• Bimodal gas accretion in the Horizon-MareNostrum galaxy formation simulation
• The First Billion Years Project: The escape fraction of ionizing photons in the epoch of reionization
• Feedback-regulated star formation and escape of LyC photons from mini-haloes during reionisation
• A radiative transfer scheme for cosmological reionization based on a local Eddington tensor
• Reionization with galaxies and active galactic nuclei
• Understanding the escape of LyC and Ly$\alpha$ photons from turbulent clouds
• The Physics and Early History of the Intergalactic Medium
• High redshift AGNs and HI reionisation: limits from the unresolved X-ray background
• Simulating the effect of photoheating feedback during reionization
• On the origin of low escape fractions of ionizing radiation from massive star-forming galaxies at high redshift
• On the Proper Use of the Reduced Speed of Light Approximation

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