  The Chinese Space Station Optical Survey (CSS-OS) is a planned full sky
survey operated by the Chinese Space Station Telescope (CSST). It can
simultaneously perform the photometric imaging and spectroscopic slitless
surveys, and will probe weak and strong gravitational lensing, galaxy
clustering, individual galaxies and galaxy clusters, active galactic nucleus
(AGNs), and so on. It aims to explore the properties of dark matter and dark
energy and other important cosmological problems. In this work, we focus on two
main CSS-OS scientific goals, i.e. the weak gravitational lensing (WL) and
galaxy clustering surveys. We generate the mock CSS-OS data based on the
observational COSMOS and zCOSMOS catalogs. We investigate the constraints on
the cosmological parameters from the CSS-OS using the Markov Chain Monte Carlo
(MCMC) method. The intrinsic alignments, galaxy bias, velocity dispersion, and
systematics from instrumental effects in the CSST WL and galaxy clustering
surveys are also included, and their impacts on the constraint results are
discussed. We find that the CSS-OS can improve the constraints on the
cosmological parameters by a factor of a few (even one order of magnitude in
the optimistic case), compared to the current WL and galaxy clustering surveys.
The constraints can be further enhanced when performing joint analysis with the
WL, galaxy clustering, and galaxy-galaxy lensing data. Therefore, the CSS-OS is
expected to be a powerful survey for exploring the Universe. Since some
assumptions may be still optimistic and simple, it is possible that the results
from the real survey could be worse. We will study these issues in details with
the help of simulations in the future.
