2018-MNRAS-477_1984-1992-Bag.pdf (1018.03 kB)
The shape and size distribution of H II regions near the percolation transition
journal contribution
posted on 2023-06-09, 18:06 authored by Satadru Bag, Rajesh Mondal, Prakash Sarkar, Somnath Bharadwaj, Varun SahniUsing Shapefinders, which are ratios of Minkowski functionals, we study the morphology of neutral hydrogen (H?I) density fields, simulated using seminumerical technique (inside-out), at various stages of reionization. Accompanying the Shapefinders, we also employ the ‘largest cluster statistic’ (LCS), originally proposed in Klypin & Shandarin, to study the percolation in both neutral and ionized hydrogen. We find that the largest ionized region is percolating below the neutral fraction xHI?0.728 (or equivalently z ? 9). The study of Shapefinders reveals that the largest ionized region starts to become highly filamentary with non-trivial topology near the percolation transition. During the percolation transition, the first two Shapefinders – ‘thickness’ (T) and ‘breadth’ (B) – of the largest ionized region do not vary much, while the third Shapefinder – ‘length’ (L) – abruptly increases. Consequently, the largest ionized region tends to be highly filamentary and topologically quite complex. The product of the first two Shapefinders, T × B, provides a measure of the ‘cross-section’ of a filament-like ionized region. We find that, near percolation, the value of T × B for the largest ionized region remains stable at ~7?Mpc2 (in comoving scale) while its length increases with time. Interestingly, all large ionized regions have similar cross-sections. However, their length shows a power-law dependence on their volume, L ? V0.72, at the onset of percolation.
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Publication status
- Published
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- Published version
Journal
Monthly Notices of the Royal Astronomical SocietyISSN
0035-8711Publisher
WileyExternal DOI
Issue
2Volume
477Page range
1984-1992Department affiliated with
- Physics and Astronomy Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2019-06-19First Open Access (FOA) Date
2019-06-19First Compliant Deposit (FCD) Date
2019-06-17Usage metrics
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