Beschreibung
Source Injection produces synthetic source catalog by running the image reduction pipeline. The process replicates the complicated process from image to catalogs. The synthetic galaxies produced from source injection have similar observational systematics as real galaxies.
When a galaxy sample is selected, it occupies a continuous color space. Then galaxies within this sample may respond differently to various systematics. For example, fainter sources are more sensitive to galactic depth than brighter galaxies. If we model then as if all sources have the same systematics, the cosmological measurements may be biased. I call this effect “sub-sample systematics”.
I will first introduce my work in DESI and Euclid Source Injection. I will discuss how to mitigate sub-sample systematics with Source Injection, and discuss my on-going work of integrating it with field-level inference.