Forecasting Constraint on the $f(R)$ Theory with the CSST SN Ia and BAO Surveys

The $f(R)$ modified gravity theory can explain the accelerating expansion of the late Universe without introducing dark energy.

In this study, we predict the constraint strength on the $f(R)$ theory using the mock data generated from the China Space Station Telescope (CSST) Ultra-Deep Field (UDF) Type Ia supernova (SN Ia) survey and wide-field slitless spectroscopic baryon acoustic oscillation (BAO) survey.

We explore three popular $f(R)$ models, and introduce a parameter $b$ to characterize the deviation of the f(R) theory from the $\Lambda$CDM theory.

The Markov Chain Monte Carlo (MCMC) method is employed to constrain the parameters in the $f(R)$ models, and the nuisance parameters and systematical uncertainties are also considered in the model fitting process.

Besides, we also perform model comparisons between the $f(R)$ models and the $\Lambda$CDM model.

We find that the constraint accuracy using the CSST SN Ia+BAO dataset alone is comparable to or even better than the result given by the combination of the current relevant observations, and the CSST SN Ia+BAO survey can distinguish the $f(R)$ models from the $\Lambda$CDM model.

This indicates that the CSST SN Ia and BAO surveys can effectively constrain and test the $f(R)$ theory.

;Comment: 15 pages, 3 figures, 2 tables.

Accepted for publication in RAA