Hi, I'm a new user of the data access, currently working on PhD in applied mathematics.
I'm currently trying to use Python to create a data plot that shows filament structure in the simulations as clearly as possible. For example, I'd like to reproduce the 3D versions of the Figures 3 and 4 from this paper.
The right command to use seems to be "SubfindDMDensity" (as shown on this discussion page), but being quite new to IllustrisTNG, I need some help with basics of this. For example, I don't understand what Group catalog or Subfind really means.
Could someone tell me how I should use the "SubfindDMDensity" command to access dark matter density / baryon density?
I understand that the discussion page linked above supposedly answers my query, but I can't currently write a working script from the answers there.
There are two types of data: snapshot data, and catalog data.
To make a visualization like the images you reference, you need to use the snapshot data. The catalogs are not relevant.
"SubfindDMDensity" is a particular field in the snapshot data, just like "Coordinates" (which you would also need to make such a visualization). You can load this data, and then visualize it, by starting with the Example Scripts Getting Started tutorial, for example.