Thanks for the link. They identified the galaxy they're studying because it happens to be backlit by an even more-distant quasar. Galaxies identified this way

Thanks for the link. They identified the galaxy they're studying because it happens to be backlit by an even more-distant quasar. Galaxies identified this way are not "special" in the sense that highly-luminous galaxies are. (That is, this selection method avoids the obvious bias of just studying really bright high-z galaxies.) As a small aside, it's really impressive how routine tailored MCMC analysis has become in astrophysics.