I was wandering is there a way to get local dark matter only densities in illustris-3?
I read a similar question for TNG100 but I couldn't find "SubfindDMDensity" field in snap data for illustris-3 . Isn't the field "SubfindDensity" in dm type includes all the particles not just dm?
You're right the field SubfindDMDensity is available only in the TNG snapshots, not in the original Illustris snapshots. If you need something which has already been computed for both, and total matter density (including all particle types, not just DM), then you could use SubfindDensity.