Public Data Access Overview / Discussion Forum

Hi Dylan,

For PartType3 (tracers), the snashot data only provide FluidQuantities, ParentID, and TracerID. However, how can I get the other parameters (i.e. positions, metallicities of gas parents) of the tracer particles if I focus on some given regions? For example, I want to confirm the cold gas whether come from the outside of the virial radius.

Thank you.

Please see this thread.

One more question: TNG-Cluster seems to have no tr_all_*_pos.hdf5 or *_temp.hdf5 data?

TNG-Cluster does not have any of the tracer_tracks files at all.

This is because the tracers in TNG-Cluster have been ordered, making these files (largely) unnecessary.

We could possibly compute them, but I think you will find it fairly easy to write the script to compute them. Because the tracers are ordered, you only need to identify the indices of parents, given the parent IDs. You can do this within each original zoom run, meaning the data volumes are small.

It means I do no even need to load the TracerID. I only need to do is to determine the intersection of the gas ParticleID and the tracer ParentID. With it, I can get the gas, star or BH corresponding to the tracer at any snapshot. Sounds good! Thank you so much!

Hi Dylan,

For TNG-Cluster, I found the total mass of the gas traced is short of the total gas mass.

snapNum = 99

gas_mass = il.snapshot.loadOriginalZoom(basePath, snapNum, 0, 'gas', 'Masses')
gas_id = il.snapshot.loadOriginalZoom(basePath, snapNum, 0, 'gas', 'ParticleIDs')

ParentID = il.snapshot.loadOriginalZoom(basePath, snapNum, 0, 'tracer', 'ParentID')

cut_parent = np.isin(ParentID, gas_id)

N_tracer_gas = np.sum(cut_parent)

print('M_gas: '+str(np.sum(gas_mass))+'e10 M_sun/h')
print('M_gas_tracing: '+str(N_tracer_gas*0.000771495)+'e10 M_sun/h')

M_gas: 424076500.0e10 M_sun/h
M_gas_tracing: 149936.199632475e10 M_sun/h

So how can I deduce the evolution of the gas from the tracer particles?

Tracers have three possible parent types: gas, stars, and SMBHs.