Hello Dylan and Illustris team.
I'm Lucas, and I just started using the IllustrisTNG data, in particular the group catalogues. In the analysis I'm trying to do, I need the star-forming gas mass of a given galaxy (let's say, the mass of gas cells which are star-forming), but I can't find this value in the Subhalo fields. Is there some entry/entries in the Subhalo catalogues that I could use to calculate the star-forming gas mass, without having to use the particle data?
Many thanks in advance!
Unfortunately no, the only fields which exist are those described in the documentation.
But you can calculate this by loading the StarFormationRate and Masses for gas cells for that subhalo, and taking e.g. np.sum(Masses[np.where(StarFormationRate > 0)]).
np.sum(Masses[np.where(StarFormationRate > 0)])
OK then, I'll calculate it using the gas cells that have SFR>0.