Redshift drift exploration for interacting dark energy

By detecting redshift drift in the spectra of the Lyman-α forest of distant quasars, the Sandage-Loeb (SL) test directly measures the expansion of the universe, covering the ''redshift desert'' of 2 c, (ii) Q = γHρ_de, (iii) Q = γH₀ρ_c, and (iv) Q = γH₀ρ_de. The results show that for all the considered interacting dark energy models, relative to the current joint SN + BAO + CMB + H₀ observations, the constraints on Ω_m and H₀ would be improved by about 60 and 30-40 %, while the constraints on w and γ would be slightly improved, with a 30-year observation of the SL test. We also explore the impact of the SL test on future joint geometric observations. In this analysis, we take the model with Q = γHρ_c as an example, and we simulate future SN and BAO data based on the space-based project WFIRST. We find that with the future geometric constraints, the redshift drift observations would help break the geometric degeneracies in a meaningful way, thus the measurement precisions of Ω_m, H₀, w, and γ could be substantially improved using future probes. (orig.)