Local Group Dwarf Galaxy Detection Limit in the CSST survey

TL;DR

The paper predicts the detection limits of dwarf galaxies in the upcoming CSST survey, highlighting its potential to discover extremely faint and distant low-mass galaxies across a large sky area.

Contribution

It provides a detailed estimation of dwarf galaxy detection capabilities for CSST, including magnitude, surface brightness, and distance limits based on mock survey data.

Findings

CSST can detect dwarf galaxies with M_V = -3.0 at 400 kpc.

Detection limits extend to M_V = -5.8 at 1-2 Mpc.

Survey will significantly expand knowledge of faint dwarf galaxies.

Abstract

We predict the dwarf galaxy detection limits for the upcoming Chinese Space Station Telescope (CSST) survey that will cover 17,500 deg$^{2}$ of the sky with a wide field of view of 1.1 deg$^2$. 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 $M_V = -3.0$ and $\mu_{250} = 32.0$ mag/arcsec$^2$ (surface-brightness limit for a system of half-light radius $r_{\rm h}$ = 250 pc at 400 kpc, and $M_V = -4.9$ and $\mu_{250} = 30.5$ mag/arcsec$^2$ around the Andromeda galaxy. Beyond the Local Group, the CSST survey will achieve $M_V = -5.8$, and $\mu_{250}$ = 29.7 mag/arcsec$^2$ 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.