Tianlai: a 21cm radio telescope array for BAO and dark energy, status and progress

The Tianlai project is a 21cm intensity mapping experiment dedicated to the survey of the neutral hydrogen in the Universe below redshift 3. Through this survey, one could probe the large-scale structure and detect baryon acoustic oscillation (BAO) features to constrain dark energy models. The construction of the Tianlai cylinder and dish pathfinder arrays have been completed at the end of 2015, the two arrays are now undergoing the commissioning process.