I have a question about the dimension of the data, how can we define/determine it and what does it depend?

For example, Parent Halo ID: 1596, in the Gas section, there are 110,203 data. So according to the Data Specifications, it is the dimension N; I wonder that if the N here is randomly for each ID because I cannot find any relation with the number 110,203. As far as I know, TNG simulation is a cube, so I think N here should be a perfect cube number (volume) or maybe a perfect square number (area of a snapshot); however, it turns out neither of them.

Thank you in advance,
Thang Huynh

Dylan Nelson

9 Aug '23

In the Data Specifications for the snapshot data, N refers to the total number of particles/cells of that type.

If instead you are considering a cutout of a single (sub)halo, then N would be the total number of particles/cells of that type in that (sub)halo.

The spatial domain of each simulation is a (periodic) cube.

The total number of dark matter particles is constant, and is also an integer cubed, e.g. 1820^3 in the case of TNG100-1. However, the number of e.g. gas cells is not constant, changes with time, and is not exactly 1820^3.

Dear all,

I have a question about the dimension of the data, how can we define/determine it and what does it depend?

For example, Parent Halo ID: 1596, in the Gas section, there are 110,203 data. So according to the Data Specifications, it is the dimension N; I wonder that if the N here is randomly for each ID because I cannot find any relation with the number 110,203. As far as I know, TNG simulation is a cube, so I think N here should be a perfect cube number (volume) or maybe a perfect square number (area of a snapshot); however, it turns out neither of them.

Thank you in advance,

Thang Huynh

In the Data Specifications for the snapshot data,

`N`

refers to the total number of particles/cells of that type.If instead you are considering a cutout of a single (sub)halo, then

`N`

would be the total number of particles/cells of that type in that (sub)halo.The spatial domain of each simulation is a (periodic) cube.

The total number of dark matter particles is constant, and is also an integer cubed, e.g.

`1820^3`

in the case of TNG100-1. However, the number of e.g. gas cells is not constant, changes with time, and is not exactly 1820^3.