In the current state of my research I want to clearly understand if a galaxy is elliptical or not and have been trying to come to a definite conclusion using several parameters, such as SDSS & POGS image datas and general information provided for each subhalo. Yet my conclusions have been unsatisfactory and I was hoping if you could help me advance my research in this particular area.
So my main questions are: How do I know if a galaxy is elliptical or spiral?
How do I calculate the ellipticity?
Is there any healthy way of defining axes for the galaxies within the simulation?
Hi. You should take a look at Xu et al.. In this work, they fit Sérsic profiles to TNG galaxies and classify them as ETG or LTG based on their Sérsic index value. About the ellipticity, they also discuss how to define the axis ratio, from which is straightforward to obtain the ellipticity. When defining axes for the galaxies, you could use the simulation box axes relative to the galaxies' center.
I hope it helps.
Thank you for your answer! I do think this paper will shed light on the questions and unresolved suspicions I have. The string of the calculations leading up to the axis ratio seems paramount and quite useful. Hopefully the paper will help me in future research also.