I would like to compute the cooling time of the most massives subhalo of Illustris-TNG 300 given by
tcool = (ne + ni)kbT / neni cooling_function. where ni and ne are the ion and electron number density.
I saw the answer 4 of the FAQ which give the temperature of the gas cells based on the electron density and internal energy.
However, i was wondering if the hydrogen mass fraction given in the FAQ (Xh = 0.76) was the same for every halo and snapshot. I thought that the hydrogen fraction increase with redshift and also depends on halo mass.
Since the ion density also depends on the mean molecular weight, does the formula in the FAQ can be apply to any gas cells? (the molecular weight should also depends on the metallicity right?)
I'm sorry i just found the previous answer about it. Abundances are in ['GMF_Metals'] keys.