I was wondering if there exists a catalogue of spectral information for the subhalos in IllustrisTNG? I am interested in finding or calculating the H alpha flux for galaxies I have previously identified via their subhalo IDs.
Alternatively, do you know of any studies which have created such a catalog? I have found a few papers describing creating artificial spectral energy distributions for high-redshift galaxies in Illustris (e.g. Figure 3, Shen+20) for their own uses, but am not certain where to go from here.
Many thanks,
Charlie
Dylan Nelson
23 Sep '20
Hello Charlie,
There are many different ways to try to do this. The most simple would be to apply a conversion factor to convert from star formation rate, to H-alpha. You could apply this either to SubhaloSFR (i.e. one number per object), or at the level of individual gas cells (PartType0/StarFormationRate), which would let you do things like make H-alpha images, calculate radial profiles, etc. This second approach was adopted in Pillepich+ (2019), you can find details and the equation there.
This ignores many complications and details, which may be important, including (dust) obscuration effects. One could also use a radiative transfer post-processing code such as SKIRT to make more accurate predictions for various optical emission lines, but this would be a much more advanced step.
Charles Walker
23 Sep '20
Dear Dylan,
Thanks again for some really useful information. I'll take a look and get to work.
Hello,
I was wondering if there exists a catalogue of spectral information for the subhalos in IllustrisTNG? I am interested in finding or calculating the H alpha flux for galaxies I have previously identified via their subhalo IDs.
Alternatively, do you know of any studies which have created such a catalog? I have found a few papers describing creating artificial spectral energy distributions for high-redshift galaxies in Illustris (e.g. Figure 3, Shen+20) for their own uses, but am not certain where to go from here.
Many thanks,
Charlie
Hello Charlie,
There are many different ways to try to do this. The most simple would be to apply a conversion factor to convert from star formation rate, to H-alpha. You could apply this either to
SubhaloSFR(i.e. one number per object), or at the level of individual gas cells (PartType0/StarFormationRate), which would let you do things like make H-alpha images, calculate radial profiles, etc. This second approach was adopted in Pillepich+ (2019), you can find details and the equation there.This ignores many complications and details, which may be important, including (dust) obscuration effects. One could also use a radiative transfer post-processing code such as SKIRT to make more accurate predictions for various optical emission lines, but this would be a much more advanced step.
Dear Dylan,
Thanks again for some really useful information. I'll take a look and get to work.
Cheers,
Charlie