About DM particles of different halos

Zhixing Li
  • 22 Feb

Hi Dylan,

Sorry to bother you, but recently I've met some problem when I tried to use the DM particle data of the z=0 snapshot. I've download the snapshot data, and I want to calculate the properties of halos, such as concentration and accretion rate, which need the data of DM particles, but I cannot tell which halo the DM particles belong to from the snapshot data.

Fortunately, I've found the "simulation.hdf5" file, which, seems to be a useful tool for me, but I got more confused after I read the description about this file. Firstly, I can't tell what language it uses, it's not Linux or python or anything.
Secondly, it says that I can download a halo's particle, but if I want to calculate all of the halos' properties, it's not realistic to download halos' particle data one by one(I mean one halo by one halo here).

So I have to ask for your help. Is "offset" file useful? If not, what method do you suggest me to use?

Thanks for reading my question! Look forward to your reply!

Zhixing Li
  • 22 Feb

uploading 1.png

Dylan Nelson
  • 26 Feb

Hello Zhixing,

First, have you downloaded the entire z=0 snapshot? Or, equally well, using the Lab service?

In either case, I would suggest to follow the Example Scripts (Getting Started Guide). At the very end, all the star particles of a single halo are loaded with the command

stars = il.snapshot.loadHalo(basePath,135,100,'stars')

you can use a similar command to load the DM particles.

(These scripts use the "offset" files, but you don't have to work with these directly).

Zhixing Li
  • 28 Feb

Oh! I'm too negligent to find this example command.
So sorry to take up your time and thanks so much for your patience!

Zhixing Li
  • 28 Feb

Oh! I'm too negligent to find this example command.
So sorry to take up your time and thanks so much for your patience!

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