Model-independent constraints on dark energy and modified gravity with the SKA

Understand

Employing a nonparametric approach of the principal component analysis (PCA), we forecast the future constraint on the equation of state $w(z)$ of dark energy, and on the effective Newton constant $\mu(k,z)$, which parameterise the effect of modified gravity, using the planned SKA HI galaxy survey.

• Combining with the simulated data of Planck and Dark Energy Survey (DES), we find that SKA Phase 1 (SKA1) and SKA Phase 2 (SKA2) can well constrain $3$ and $5$ eigenmodes of $w(z)$ respectively.
• The errors of the best measured modes can be reduced to 0.04 and 0.023 for SKA1 and SKA2 respectively, making it possible to probe dark energy dynamics.
• On the other hand, SKA1 and SKA2 can constrain $7$ and $20$ eigenmodes of $\mu(k,z)$ respectively within 10\% sensitivity level.