Star formation history

Mojtaba Raouf
  • 29 Jan

Hi,

I wonder to know whether the SFH estimated for galaxies in TNG100?

I found the stellar_assembly HDF5 file for ExSitu and InSitu Mass, but do you know how I can calculate the mass summed over all progenitors at 1 Gyr look-back time?

Best,
Mojtaba

Dylan Nelson
  • 29 Jan

Hi Mojtaba,

There are two ways to measure the SFH of a TNG galaxy:

i) load all the star particle ages (using the GFM_StellarFormationTime field) at a final time, e.g. z=0. convert these ages into lookback times, and then take a histogram, which gives SFR(t).

ii) use the merger tree of a galaxy, in particular it's main progenitor branch, and plot e.g. SubhaloSFRinRad versus SnapNum, converting the latter into lookback time.

Note that these two have somewhat of a different physical meaning. Method (i) is, for example, directly comparable to how SFHs are derived for Local Group dwarf galaxies. Method (ii) is more theoretical and less observationally accessible.

Mojtaba Raouf
  • 3
  • 13 Apr

Hi Dylan,

Thanks for your response. I found that there is "stellarage" for all galaxies in both TNG50 & TNG100 through the online-plot web site but those aren't exist in the group cats.
I can do it for individual galaxies by get the cutout, but its a bit long process for all when I faced on loading error for cutout due to an internet connection issues.
I wonder to know whether you can send me the stellar age (2Re or Re) same as online-plot in a separate file include IDs for all galaxies in TNG50/100? just for z = 0.

Best,
Mojtaba

Mojtaba Raouf
  • 1
  • 13 Apr

.

Dylan Nelson
  • 13 Apr

Hello,

You can find two datasets here:

www.tng-project.org/files/TNG100-1_StellarAges/Subhalo_StellarAge_30pkpc_rBandLumWt_099.hdf5

www.tng-project.org/files/TNG50-1_StellarAges/Subhalo_StellarAge_30pkpc_rBandLumWt_099.hdf5

these are, for each subhalo, the mean r-band luminosity weighted stellar ages within a 3d aperture of 30 pkpc. If you need a different definition or measurement, as you describe above, you can compute by using cutouts, or using the Lab (best to only do this for the subhalos you care about to save time).

Mojtaba Raouf
  • 14 Apr

Great. Thanks

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