Hello, I am writing in with a question regarding the nucleus of dark matter halos. My purpose is to plot a 2D-histogram with stars, gas and nucleus of dark matter halos for a certain subhalo. The objective is to localize a satellite galaxy close to my main subhalo. The question is: how can I identify the particles that conform the nucleus of dark matter halos for the central and satellite galaxies? I am using the API in my code to download the data.
Thank you in advance.
Dylan Nelson
24 Mar '22
Hi Santiago,
It depends how you would like to define the nucleus. If you want just a spatial definition, e.g. R < 5 kpc, then you can calculate the distance to every particle and find those near the center.
Or you could use a non-spatial definition, e.g. related to the gravitational potential. You could select the N most bound particles, using the "Potential" field in the snapshots.
Santiago Hernández
24 Mar '22
Hi Dylan.
Yes I understand but my problem is that I'd have two DM nucleus (in the hypothesis that I have a small satellite galaxy close to my main subhalo). In this case, I'd have two centers, one for the main subhalo and another for the satellite which I want to plot together. In this sense, I suppose I have to manage to localize these small satellites since, as far as I know, they are not identified in the simulation. Or can I get direct outputs for a satellite galaxy?
Dylan Nelson
24 Mar '22
Yes you should use the subhalo catalogs - these include all substructures identified, down to a minimum of 20 particles.
Each entry in the subhalo catalog has a SubhaloPos entry, which gives you the localized position.
Each entry is also one of two types: a "central", or a "satellite", so you can separate these two categories.
Hello, I am writing in with a question regarding the nucleus of dark matter halos. My purpose is to plot a 2D-histogram with stars, gas and nucleus of dark matter halos for a certain subhalo. The objective is to localize a satellite galaxy close to my main subhalo. The question is: how can I identify the particles that conform the nucleus of dark matter halos for the central and satellite galaxies? I am using the API in my code to download the data.
Thank you in advance.
Hi Santiago,
It depends how you would like to define the nucleus. If you want just a spatial definition, e.g. R < 5 kpc, then you can calculate the distance to every particle and find those near the center.
Or you could use a non-spatial definition, e.g. related to the gravitational potential. You could select the N most bound particles, using the "Potential" field in the snapshots.
Hi Dylan.
Yes I understand but my problem is that I'd have two DM nucleus (in the hypothesis that I have a small satellite galaxy close to my main subhalo). In this case, I'd have two centers, one for the main subhalo and another for the satellite which I want to plot together. In this sense, I suppose I have to manage to localize these small satellites since, as far as I know, they are not identified in the simulation. Or can I get direct outputs for a satellite galaxy?
Yes you should use the subhalo catalogs - these include all substructures identified, down to a minimum of 20 particles.
Each entry in the subhalo catalog has a
SubhaloPosentry, which gives you the localized position.Each entry is also one of two types: a "central", or a "satellite", so you can separate these two categories.
Thank you very much, this is what I needed