Cosmology from the EoR/Cosmic Dawn with the SKA

TL;DR

The paper discusses how the SKA telescope will enable high-precision measurements of the 21 cm signal from the early universe, providing new insights into cosmology and fundamental physics during the Epoch of Reionization and Cosmic Dawn.

Contribution

It outlines the potential of SKA to distinguish cosmological information from astrophysical effects in 21cm observations, and explores methods to extract fundamental physics constraints.

Findings

SKA will enable high signal-to-noise measurements of 21cm fluctuations.

Potential to constrain cosmological parameters and fundamental physics.

Opportunities for advanced analysis with SKA Phase 1 and SKA2.

Abstract

The SKA will build upon early detections of the EoR by precursor instruments, such as MWA, PAPER, and LOFAR, and planned instruments, such as HERA, to make the first high signal-to-noise measurements of fluctuations in the 21 cm brightness temperature from both reionization and the cosmic dawn. This will allow both imaging and statistical maps of the 21cm signal at redshifts z = 6 - 27 and constrain the underlying cosmology and evolution of the density field. This era includes nearly 60% of the (in principle) observable volume of the Universe and many more linear modes than the CMB, presenting an opportunity for SKA to usher in a new level of precision cosmology. This optimistic picture is complicated by the need to understand and remove the effect of astrophysics, so that systematics rather than statistics will limit constraints. This chapter describes the cosmological, as opposed to astrophysical, information available to SKA. Key areas for discussion include: cosmological parameters constraints using 21cm fluctuations as a tracer of the density field; lensing of the 21cm signal, constraints on heating via exotic physics such as decaying or annihilating dark matter; impact of fundamental physics such as non-Gaussianity or warm dark matter on the source population; and constraints on the bulk flows arising from the decoupling of baryons and photons at z = 1000. The chapter explores the path to separating cosmology from astrophysics, for example via velocity space distortions and separation in redshift. We discuss new opportunities for extracting cosmology made possible by the sensitivity of SKA Phase 1 and explores the advances achievable with SKA2.