Quantifying the impact of future Sandage-Loeb test data on dark energy constraints

TL;DR

This paper assesses how future Sandage-Loeb test data, especially over 30 years, can significantly improve constraints on dark energy parameters and dark matter interactions, complementing existing cosmological measurements.

Contribution

It quantifies the impact of simulated future SL test data on dark energy and dark matter interaction constraints, highlighting its potential to enhance current cosmological parameter estimates.

Findings

30-year SL test data could improve 0% on m constraints.

It could enhance the measurement of dark energy equation of state by about 25%.

SL test data can improve constraints on dark sector interaction parameters by 10-30%.

Abstract

The Sandage-Loeb (SL) test is a unique method to probe dark energy in the "redshift desert" of $2\lesssim z\lesssim 5$, and thus it provides an important supplement to the other dark energy probes. Therefore, it is of great importance to quantify how the future SL test data impact on the dark energy constraints. To avoid the potential inconsistency in data, we use the best-fitting model based on the other geometric measurements as the fiducial model to produce 30 mock SL test data. The 10-yr, 20-yr, and 30-yr observations of SL test are analyzed and compared in detail. We show that compared to the current combined data of type Ia supernovae, baryon acoustic oscillation, cosmic microwave background, and Hubble constant, the 30-yr observation of SL test could improve the constraint on $\Omega_m$ by about $80%$ and the constraint on $w$ by about $25%$. Furthermore, the SL test can also improve the measurement of the possible direct interaction between dark energy and dark matter. We show that the SL test 30-yr data could improve the constraint on $\gamma$ by about $30%$ and $10%$ for the $Q=\gamma H\rho_c$ and $Q=\gamma H\rho_{de}$ models, respectively.