I have some questions about the projected 2-D half light radius in publicly available Stellar Projected Sizes. After reading the mentioned paper I just wanted to clarify few things.
1) Subhalo center was assumed to be the center from the subfind ?
2) Considered all the stellar particles in the subhalo and it's a direct circular radius without any Sersic fitting?
(1) Yes, SubhaloPos is the center, which is what is most commonly used for any analysis.
(2) Yes, all stars in the subhalo ("gravitationally bound"), and it is a circular half-light radius.
You may also be interested in/want to compare to the SKIRT Synthetic Images and Optical Morphologies which contains much more sophisticated size measurements, including dust effects, based on Sersic fits, and so on.
Thanks Dylan. This helps me a lot