Cosmological Prediction from the Joint Observation of MeerKAT and CSST at z = 0.4 – 1.2

Abstract Cross-correlating neutral hydrogen (H i ) 21 cm intensity mapping with galaxy surveys provides an effective probe of astrophysical and cosmological information. This work presents a cross-correlation analysis between MeerKAT single-dish H i intensity mapping and Chinese Space Station Survey Telescope (CSST) spectroscopic galaxy surveys in z = 0.4 – 1.2, which will share a survey area of several thousand square degrees. Utilizing Jiutian-1G cosmological simulation, we simulate the observational data of MeerKAT and CSST with survey areas from ∼1600 to 600 deg 2 at z = 0.5, 0.7, and 1. The effect of beam pattern, polarization leakage, and different foregrounds in the MeerKAT H i intensity mapping is considered in the simulation. After employing foreground removal with the principal component analysis method and performing signal compensation, we derive the cross-power spectra of MeerKAT and CSST. We perform the joint constraint using the CSST galaxy autopower spectra and MeerKAT-CSST cross-power spectra with the least-squares fitting method. The constraint results show that, in the simulated survey area, the relative accuracy can achieve 6% – 8% for the parameter products Ω HI b HI b g r HI, g and Ω HI b HI r HI, g at the three redshifts, which is 3 – 4 times smaller than the current result. These findings indicate that the full MeerKAT-CSST joint observation with thousands of square degrees overlapping survey area can be a powerful probe of large-scale structure, and has the ability to provide information on cosmic evolution of H i and galaxies in a wide redshift range.