摘要
The expansion history and the nature of dark energy are of fundamental importance for understanding the universe.Among various dark energy probes are included the type Ia supernovae(SNe Ia),baryon acoustic oscillations(BAO),cosmic microwave background(CMB),weak lensing,and galaxy clusters.Compared with the conventional optical BAO measurement that requires millions of galaxy spectra,the newly developed 21 cm intensity mapping(IM)technique enables efficient measurements of large-scale structures inaccessible to any other known techniques.
