Forecast of cosmological constraints with type Ia supernovae from the Chinese Space Station Telescope

The 2-m aperture Chinese Space Station Telescope (CSST), which observes at wavelengths ranging from 255 to 1000 nm, is expected to start science operations in 2024. An ultra-deep field observation program covering approximately 10 deg 2 is proposed with supernovae (SNe) and other transients as one of its primary science drivers. This paper presents the simulated detection results of type Ia supernovae (SNe Ia) and explores the impact of new datasets on the determinations of cosmological parameters. The simulated observations are conducted with an exposure time of 150 s and cadences of 10, 20, and 30 d. The survey mode covering a total of 80 observations but with a random cadence in the range of 4 to 14 d is also explored. Our simulation results indicate that the CSST can detect up to ∼ 1800 SNe Ia at z < 1.3. The simulated SNe Ia are then used to constrain the cosmological parameters. The constraint on Ω m can be improved by 37.5% using the 10-d cadence sample in comparison with the Pantheon sample. A deeper measurement simulation with a 300 s exposure time together with the Pantheon sample improves the current constraints on Ω m by 58.3% and ω by 47.7%. Taking future lager sets of nearby SN Ia sample form ground-based surveys (i.e., N ∼ 3400) into consideration, the constraints on ω can be improved by 59.1%. The CSST ultra-deep field observation program is expected to discover large amounts of SNe Ia over a broad redshift span and enhance our understanding of the nature of dark energy.