Halo ID's for TNG-Cluster and cluster richness estimates
Damien Ragavan
8 Jun
Hi,
I actually have two separate, but related, questions regarding TNG-Cluster. I'm trying to measure stacked stellar mass functions for massive clusters/halos at z < 1 and study the evolution of the cluster SMF. Here are my queries:
When I load in the Group Catalog for halos at snap 99 (z = 0) for TNG-Cluster, I'm getting 555 halo/cluster indices, after applying a cluster mass threshold (using M200m). I've converted the necessary units as well. I'm curious why I don't get 352 cluster ID's. Do you have any possible suggestions? Kindly see the screenshot of my code below.
Additionally, when I construct the cluster SMFs, I calculate a richness for each halo based on subhalos that satisfy membership criteria (see second screenshot attached). However, I'm getting extremely high richness values for the first halo/cluster and then very low values for the other halos (see third screenshot with output for list of halo richnesses). I know one could use 'GroupNsubs' for this, but I'm more interested in subhalos that meet specific membership criteria. Note, I first load the subhalo catalogue for the entire snapshot before I construct the SMF.
Thanks, look forward to your reply.
Dylan Nelson
9 Jun
(1) You should use the GroupPrimaryZoomTarget field of the catalogs to identify the primary 352 clusters.
(2) I don't know what group_numbers is in your second screenshot. In general, the subhalo IDs of all the subhalos that belong to a different group are sub_ids = np.arange(GroupFirstSub[hID], GroupFirstSub[hID]+GroupNsubs[hID]). Then, you can use these sub_ids to get their corresponding properties, e.g. sub_mstar = SubhaloMassInRadType[sub_ids,4].
Damien Ragavan
9 Jun
Ok, thank you very much, this certainly helps.
Yes, sorry, I've set group_numbers = subs['SubhaloGrNr'] in my code.
Thank you.
Hi,
I actually have two separate, but related, questions regarding TNG-Cluster. I'm trying to measure stacked stellar mass functions for massive clusters/halos at z < 1 and study the evolution of the cluster SMF. Here are my queries:
Thanks, look forward to your reply.
(1) You should use the GroupPrimaryZoomTarget field of the catalogs to identify the primary 352 clusters.
(2) I don't know what
group_numbersis in your second screenshot. In general, the subhalo IDs of all the subhalos that belong to a different group aresub_ids = np.arange(GroupFirstSub[hID], GroupFirstSub[hID]+GroupNsubs[hID]). Then, you can use thesesub_idsto get their corresponding properties, e.g.sub_mstar = SubhaloMassInRadType[sub_ids,4].Ok, thank you very much, this certainly helps.
Yes, sorry, I've set group_numbers = subs['SubhaloGrNr'] in my code.
Thank you.