I'm confused by this definition. How to convert GFM_StellarFormationTime to cosmic time?

Thanks,
Guang

Dylan Nelson

21 Jul '20

Hello,

It is the scale factor a. To convert to a "lookback time" or "age of the universe" (e.g. in Gyr), you need to do the relevant cosmological calculations, e.g. as implemented in astropy.cosmology.age().

Hi,

From https://www.tng-project.org/data/docs/specifications/, I find the definition of GFM_StellarFormationTime is "The exact time (given as the scalefactor) when this star was formed".

I'm confused by this definition. How to convert GFM_StellarFormationTime to cosmic time?

Thanks,

Guang

Hello,

It is the scale factor a. To convert to a "lookback time" or "age of the universe" (e.g. in Gyr), you need to do the relevant cosmological calculations, e.g. as implemented in astropy.cosmology.age().

Yeah, that makes sense. Thanks, Dylan!