Tracking galaxies forward in time

DErrick Carr
  • 2
  • 16 Mar

I'm currently using TNG100-1 to perform merger tree analytics in the JupyterLab services (super convenient for it having all of the snapshots and data readily available). I'm currently at a point now where I have identified ~700 galaxies at snapshot 78 that I would like to identify at the final snapshot 99. The merger tree load scripts seem to only have the convenience of going backwards or forward one snapshot, but I would like help tracing them to z=0 galaxies.

One option I thought of was simply using a z=0 snapshot of all galaxies and making merger trees there to find when my ~700 galaxies appear, but that would require loading the trees of millions of galaxies (computationally too heavy)...

What would be the best way for me to trace these over 20+ snapshots forward in time?

Just to clarify, the tree is created using il.sublink.loadTree

I also found this old forum question: https://www.tng-project.org/data/forum/topic/184/a-few-questions-regarding-sublink-merger-trees/
This seems like exactly what I need regarding the main descendant branch, but onlyMDB does not exist anymore in the loadtree function... was this outdated for some reason?

DErrick Carr
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DErrick Carr
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Dylan Nelson
  • 2
  • 17 Mar

Hi,

The "main descendant branch" functionality is available in the current sublink.loadTree() function (see the source code). You can just override the sublink.py file in your Lab with this one, or add the few lines of code (138-147) which make this option work.

To be clear: this was a somewhat recent addition, so people who have had Lab accounts for quite some time, may have an old version of "illustris_python", and may wish to update.

DErrick Carr
  • 18 Mar

Your clarification makes a lot of sense, thank you!

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