ross-correlation Forecast of CSST Spectroscopic Galaxy and MeerKAT Neutral Hydrogen Intensity Mapping Surveys

ross-correlating the data on neutral hydrogen (H I) 21 cm intensity mapping with galaxy surveys is an effectivemethod to extract astrophysical and cosmological information. In this work, we investigate the cross-correlation ofMeerKAT single-dish mode H I intensity mapping and China Space Station Telescope (CSST) spectroscopicgalaxy surveys. We simulate a survey area of ～300 deg2 of MeerKAT and CSST surveys at z = 0.5 using Multi-Dark N-body simulation. The PCA algorithm is applied to remove the foregrounds of H I intensity mapping, andsignal compensation is considered to solve the signal loss problem in H I-galaxy cross power spectrum caused bythe foreground removal process. We find that from CSST galaxy auto and MeerKAT-CSST cross power spectra,the constraint accuracy of the parameter product ΩH IbH IrH I,g can reach ～1%, which is about one order ofmagnitude higher than the current results. After performing the full MeerKAT H I intensity mapping survey with5000 deg2 survey area, the accuracy can be enhanced to <0.3%. This implies that the MeerKAT-CSST crosscorrelationcan be a powerful tool to probe the cosmic H I property and the evolution of galaxies and the Universe.