Anisotropies of cosmic optical and near-IR background from the China space station telescope (CSST)

Abstract

ABSTRACT Anisotropies of the cosmic optical background (COB) and cosmic near-IR background (CNIRB) are capable of addressing some of the key questions in cosmology and astrophysics. In this work, we measure and analyse the angular power spectra of the simulated COB and CNIRB in the ultradeep field of the China Space Station Telescope (CSST-UDF). The CSST-UDF covers about 9 deg2, with magnitude limits ∼28.3, 28.2, 27.6, 26.7 AB mag for point sources with 5σ detection in the r (0.620 $\rm \mu m$), i (0.760 $\rm \mu m$), z (0.915 $\rm \mu m$), and y (0.965 $\rm \mu m$) bands, respectively. According to the design parameters and scanning pattern of the CSST, we generate mock data, merge images, and mask the bright sources in the four bands. We obtain four angular power spectra from ℓ = 200 to 2 000 000 (from arcsecond to degree), and fit them with a multicomponent model including intrahalo light (IHL) using the Markov chain Monte Carlo method. We find that, the signal-to-noise ratio of the IHL is larger than 8 over the range of angular scales that is useful for astrophysical studies (ℓ ∼10 000–400 000). Comparing to previous works, the constraints on the model parameters are improved by factors of 3∼4 in this study, which indicates that the CSST-UDF survey can be a powerful probe on the cosmic optical and near-IR backgrounds.