Exploring 21 cm-Lya Emitter Synergies for SKA
We study the signatures of reionization and ionizing properties of early galaxies in the cross-correlations between the 21 cm emission from the spin-flip transition of neutral hydrogen (H i) and the underlying galaxy population. In particular, we focus on a sub-population of galaxies visible as Lyα...
| Main Authors: | , , , |
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| Format: | Journal Article |
| Published: |
Institute of Physics Publishing
2017
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| Online Access: | http://purl.org/au-research/grants/arc/DE140100316 http://hdl.handle.net/20.500.11937/51841 |
| Summary: | We study the signatures of reionization and ionizing properties of early galaxies in the cross-correlations between the 21 cm emission from the spin-flip transition of neutral hydrogen (H i) and the underlying galaxy population. In particular, we focus on a sub-population of galaxies visible as Lyα Emitters (LAEs). With both observables simultaneously derived from a z ≃ 6.6 hydrodynamical simulation (GADGET-2) snapshot post-processed with a radiative transfer code (pCRASH) and a dust model, we perform a parameter study and aim to constrain both the average intergalactic medium (IGM) ionization state (1 – {XHI}) and the reionization topology (outside-in versus inside-out). We find that, in our model, LAEs occupy the densest and most-ionized regions resulting in a very strong anti-correlation between the LAEs and the 21 cm emission. A 1000 hr Square Kilometer Array (SKA)-LOW1—Subaru Hyper Suprime-Cam experiment can provide constraints on (XHI), allowing us to distinguish between IGM ionization levels of 50%, 25%, 10%, and fully ionized at scales r <~ 10 comoving Mpc (assuming foreground avoidance for SKA). Our results support the inside-out reionization scenario where the densest knots (under-dense voids) are ionized first (last) for (XHI) >~ 0.1. Further, 1000 hr SKA-LOW1 observations should be able to confirm the inside-out scenario by detecting a lower 21 cm brightness temperature (by about 2–10 mK) in the densest regions (>~2 arcmin scales) hosting LAEs, compared to lower-density regions devoid of them. © 2017. The American Astronomical Society. All rights reserved. |
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