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

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Date
2014Author
Zhao, Gong-Bo
Bacon, David
Maartens, Roy
Santos, Mario G.
Raccanelli, Alvise
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Show full item recordAbstract
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 m(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 m(k; z) respectively within
10% sensitivity level. Furthermore, 2 and 7 modes can be constrained within sub percent level
using SKA1 and SKA2 respectively. This is a significant improvement compared to the combined
datasets without SKA.