Local group dwarf galaxy detection limit in the CSST survey
Abstract
We predict the dwarf galaxy detection limits for the upcoming Chinese Space Station Telescope (CSST) survey that will cover 17,500 deg2 of the sky with a wide field of view of 1.1 deg2. The point-source depth reaches 26.3 mag in the g band and 25.9 mag in the i band. Constructing mock survey data based on the designed photometric bands, we estimate the recovery rate of artificial dwarf galaxies from mock point-source photometric catalogues. The detection of these artificial dwarf galaxies is strongly dependent on their distance, magnitude and size, in agreement with searches in current surveys. We expect CSST to enable the detection of dwarf galaxies with MV = -3.0 and μ250 = 32.0 mag/arcsec2 (surface-brightness limit for a system of half-light radius rh = 250 pc) at 400 kpc, and MV = -4.9 and μ250 = 30.5 mag/arcsec2 around the Andromeda galaxy. Beyond the Local Group, the CSST survey will achieve MV = -5.8, and μ250 = 29.7 mag/arcsec2 in the distance range of 1-2 Mpc, opening up an exciting discovery space for faint field dwarf galaxies. With its optical bands, wide survey footprint, and space resolution, CSST will undoubtedly expand our knowledge of low-mass dwarf galaxies to an unprecedented volume.