Hi all, I was reading something about galaxy clusters but I didn't understand how I can identify what galaxies is part of a cluster. Thanks in advance 😃
If the galaxies in a cluster have their redshift z meaured, and the distance between each member calculated and gravitational forces modelled, then a scientist might decide that it is a cluster. You can go into NED, and sometimes find labels of being a galaxy cluster, and find a scientific reference paper there that you can read. Otherwise we guess, going by colour or photoz and whether the galaxies show disturbance. I hope this helps.
If the galaxy is not symmetrical, or has tidal trails, it is likely to be disturbed. So just use your eyes and your judgement. There is no right answer, it is often a matter of opinion.