This repository is for the Fisher forecast on the Baryon Acoustic Oscillations (BAO) measured from the China Space Station Telescope (CSST) galaxy surveys.

CSST will simultaneously undertake the photometric redshift (photo-z) and slitless spectroscopic redshift (spec-z) surveys for weak lensing and galaxy clustering studies.

We forecast the BAO measurements from the spectroscopic redshift (spec-z) and photometric redshift (photo-z) surveys, respectively. Thanks to the overlapped sky area and redshift range of the two surveys, cross-correlating the spec-z and photo-z samples benefits the constraints on BAO, especially at z>1.0 for CSST. We study the systematic effects on the improvement from the joint analysis of the spec-z and photo-z clustering, including the systematic noise and the redshift success rates of the spec-z data, as well as the photo-z error. Overall, the improvement is robust from these systematics.

The methodology can be applied to other surveys with spec-z and photo-z data in the same survey volume.