Redshift Space Distortion of the 21cm Background from the Epoch of Reionization I: Methodology Re-examined

Understand

The peculiar velocity of the intergalactic gas responsible for the cosmic 21cm background from the epoch of reionization and beyond introduces an anisotropy in the three-dimensional power spectrum of brightness temperature fluctuations.

• Measurement of this anisotropy by future 21cm surveys is a promising tool for separating cosmology from 21cm astrophysics.
• However, previous attempts to model the signal have often neglected peculiar velocity or only approximated it crudely.
• This paper re-examines the effects of peculiar velocity on the 21cm signal in detail, improving upon past treatment and addressing several issues for the first time.