Opening Reionization: Quantitative Morphology of the Epoch of Reionization and Its Connection to the Cosmic Density Field

Abstract

We introduce a versatile and spatially resolved morphological characterisation of binary fields, rooted in the opening transform of mathematical morphology. We subsequently apply it to the thresholded ionization field in simulations of cosmic reionization and study the morphology of ionized regions. We find that an ionized volume element typically resides in an ionized region with radius $\sim 8h^{-1}\mathrm{cMpc}$ at the midpoint of reionization ($z\approx 7.5$) and follow the bubble size distribution even beyond the overlap phase. We find that percolation of the fully ionized component sets in when 25% of the universe is ionized and that the resulting infinite cluster incorporates all ionized regions above $\sim 8h^{-1}\mathrm{cMpc}$. We also quantify the clustering of ionized regions of varying radius with respect to matter and on small scales detect the formation of superbubbles in the overlap phase. On large scales we quantify the bias values of the centres of ionized and neutral regions of different sizes and not only show that the largest ones at the high-point of reionization can reach $b\approx 30$, but also that early small ionized regions are positively correlated with matter and large neutral regions and late small ionized regions are heavily anti-biased with respect to matter, down to $b\lesssim -20$.

18 pages, 15 figure, as accepted for publication by MNRAS

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Cited by in corpus (9)

• Introducing the THESAN project: radiation-magnetohydrodynamic simulations of the epoch of reionization
• The THESAN project: connecting ionized bubble sizes to their local environments during the Epoch of Reionization
• Ionizing photon production and escape fractions during cosmic reionization in the TNG50 simulation
• Investigating X-ray sources during the epoch of reionization with the 21 cm signal
• Cosmological Probes of Structure Growth and Tests of Gravity
• A galaxy-free phenomenological model for the 21-cm power spectrum during reionization
• A CRASH simulation of the contribution of binary stars to the epoch of reionization
• Topology of Reionisation times: concepts, measurements and comparisons to gaussian random field predictions
• Reionization Parameter Inference from 3D Minkowski Functionals of the 21 cm Signals