I am working with the TNG50 data and am specifically accessing snapshot 99. I have a list of subhalos (obtained by placing some constraints in the Subhalo search portal) from which I need to know which of these are actually centrals and which are satellites. I came across this variable "primary_flag" which supposedly classifies a subhalo as a central or a satellite. Is it correct that if this variable is 1, the subhalo id a central galaxy and if it is 0, then it is a satellite galaxy?
Yes that's correct, just be aware this is reporting the "answer" based on Subfind, exactly as described in the group catalog docs. So this is a theory perspective on what it means to be a central vs satellite, and one may want to compute a different classification based on e.g. what one could do in observations.
Got it! Thanks:)