Public Data Access Overview / Discussion Forum

Hey everyone, I am currently doing a research about investigating the relationship between the dark halo and stellar halo for the Milky Way for distance of more than 300kpc from the galactic centre. I was hoping to use TNG100 (I'm not sure the difference between the normal one and the dark) to see whether this simulation would give me some insight about it. However, I was going through the API method to extract data and I slightly unsure on which file and where to find these specific headers. Firstly, I am interested in plotting the stellar mass and halo mass (for cases of more than 300kpc) against the redshift(from z=0 to z=10 or more) as I would like to see if they show the same trend and it would be great also if there is a way to plot the density over the distance( to see what does the simulation tells about the tides cutoff). Lastly, I am interested in the distribution for [Fe/H] < -1 stars at the halo and velocity for satellite galaxies, what kind of file should I extract?

I am slightly familiar with python and I be aiming to use it for the plotting via API method. If you happen to know some relevant paper for this case, do let me know to.

Thank you,
Matthew

I would start with the API Getting Started Guide or the Scripts Getting Started Guide.

Note that "beyond 300 kpc" means beyond the halo, generally speaking. So in order to make this kind of analysis, you will need to consider (i.e. load) all particles in the simulation, and not just particles which belong to a specific halo.

Hello,

I had go through and I still slightly confuse, I tried to find galaxy which is Milky Way like and wanted to plot the number density of stars and DM with respect from galactic centre. I tried to check every subhalo and it has it on Len(DM) and Len(Stars) but how do I plot the dispersion( as in what kind of file I need to focus).

Thanks

Once you have a particular subhalo you are interested in, you should load the Coordinates of all the dark matter particles of that subhalo. Then you can calculate the distance of each from the center of the subhalo. You can then histogram these distances in radial distance bins to compute a radial profile.

Hello Dylan, Thank you for the response and I able to do it. Moving on from that, I am interested in plotting these radial profile and compare it with different redshifts. I did read some discussion forum that require to download some merger trees? I am confuse on which cutout file or specific file that I could trace these radial profile with different redshifts (Is it related to Lhalotree file or tracer file?). Moreover, it would also be great if I can access individual dark matter particle coordinates and it's different redshifts (small increments). Does that require me to download separate subbox file?

Apologies if there is a lot of question and hope you could give some guidance regarding this problem. Thank you.

You should download the "main progenitor branch" of the SubLink tree. From it, all you need is the SubfindID of the progenitor, at each snapshot. Then you can loop over snapshots 99, 98, 97, and for each, load the DM particles of the corresponding subhalo.

If you just want to do this for 1 subhalo, you could use the API, you will find the progenitor information called prog_snap and prog_sfid.