I have a question about the HI column density maps from TNG50-1: how does the TNG team distinguish HI gas particles from other gas phases in the simulation?
Any details you can share about your HI particle selection criteria and column‐density calculation would be extremely helpful.
Thank you in advance for your assistance.
Dylan Nelson
30 Jun
It seems there is a rotation or difference in viewing angle, more than anything else?
Note that the maps from the "Visualize" tool are for information only, they do not correspond to any "official" results (or published paper). The "HI_BR" means that the molecular hydrogen contribution is estimated using the Blitz & Rosolowsky (2006) model (and then removed). In addition, the "Visualize" tool is currently using values computed following Popping+2019, where you will find more details.
All that said, central holes in disk gas distributions are not unexpected, for a stellar mass scale of ~10.5-11.0. This is where the kinetic feedback mode of the SMBHs turns on and starts to quench galaxies. There are several papers that touch on this, one is Nelson+2021 that deals with "inside-out quenching".
Gauri Sharma
30 Jun
Thanks, Dylan.
I agree that central holes are expected in disk galaxies. When I saw a smooth distribution in the visualization tool, I began to doubt my prescription—thank you for clarifying. For the mock, the inclination is set to 45°, which is similar to the view in TNG’s visualization (neither appears edge‑on).
On a related note, is there any way to find out the aperture size used by the “Visualize” tool over which it computes column density or H α luminosity?
Dylan Nelson
30 Jun
These are options that can be chosen: "image size", "size in units of", and "projection depth fraction".
I have a question about the HI column density maps from TNG50-1: how does the TNG team distinguish HI gas particles from other gas phases in the simulation?
For making mocks, I am currently using the HI prescriptions of Stevens et al. (2019)\href{https://academic.oup.com/mnras/article/483/4/5334/5255193}{–MNRAS, 483, 5334} and Gebek et al. (2023)\href{https://academic.oup.com/mnras/article/521/4/5645/7084047}{–MNRAS, 521, 5645}, and in my own NHI maps I consistently see a central “hole” in the HI distribution that does not appear in the TNG50-1 maps (downloaded from Visualize Galaxies and Halos platform).
Any details you can share about your HI particle selection criteria and column‐density calculation would be extremely helpful.
Thank you in advance for your assistance.
It seems there is a rotation or difference in viewing angle, more than anything else?
Note that the maps from the "Visualize" tool are for information only, they do not correspond to any "official" results (or published paper). The "HI_BR" means that the molecular hydrogen contribution is estimated using the Blitz & Rosolowsky (2006) model (and then removed). In addition, the "Visualize" tool is currently using values computed following Popping+2019, where you will find more details.
All that said, central holes in disk gas distributions are not unexpected, for a stellar mass scale of ~10.5-11.0. This is where the kinetic feedback mode of the SMBHs turns on and starts to quench galaxies. There are several papers that touch on this, one is Nelson+2021 that deals with "inside-out quenching".
Thanks, Dylan.
I agree that central holes are expected in disk galaxies. When I saw a smooth distribution in the visualization tool, I began to doubt my prescription—thank you for clarifying. For the mock, the inclination is set to 45°, which is similar to the view in TNG’s visualization (neither appears edge‑on).
On a related note, is there any way to find out the aperture size used by the “Visualize” tool over which it computes column density or H α luminosity?
These are options that can be chosen: "image size", "size in units of", and "projection depth fraction".