Speaker
Description
The cosmic dawn (CD) of the first luminous objects and eventual epoch of reionisation (EoR) of the intergalactic medium (IGM) remain among the greatest mysteries in modern cosmology. The 21-cm line is one of the most powerful probes of these crucial moments in the history of the Universe, providing a clean window into both cosmology and astrophysics. It has unmatched potential, ultimately able to provide us with a 3D map of more than half of our observable Universe, as expected with the SKA. With its upcoming science verification phase, it is especially important to quantify its detection potential for CD/EoR science. The first step to forecasting the SKA observation potential is to produce a large mock observation with state-of-the-art cosmology and astrophysics.
In this work, we perform a 2 cGpc simulation, the largest simulation ever made with a semi-analytical model with 1.5 cMpc resolution, as the 2025 installment of the Evolution of 21-cm Structure (EOS) project with the new v4 release of 21cmFAST. EOS25 improves over the previous releases with the inclusion of a discrete source model based on stochastic sampling of conditional mass functions and semi-empirical galaxy relations which only became available with 21cmFASTv4. All summary observables from EOS25 are consistent with current observations. In particular, the halo catalogs produced by EOS25 are consistent with those from JWST after applying the same selection criteria.
We then use 21cmSense to forecast SKA sensitivities for the AA$^\ast$ and AA4 configurations as well as 18m and 12m substation layouts. Using EOS25 and our simulated sensitivities for the mock observation, we perform a set of inferences with the publicly available 21cmEMU emulator suite. We find that SKA AA$^\ast$ will allow us to constrain the EoR history to the percent-level, providing us with the reionisation midpoint within 0.03. We also find that we can constrain the 21-cm PS to over 7σ at redshifts less than 8. We recover the Thomson scattering optical depth to the CMB ($\tau_e$) with a 20 tighter 1σ than Planck18. Finally, our inferences show that for CD/EoR science, AA$^\ast$ is just as constraining as AA4.
| Topics | Epoch of Reionization and Cosmic Dawn |
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