... Gravitational wave search provides insights into galaxy evolution and mergers . ... galaxies . ... Large galaxies stopped growing 7 billion years ago . ... By studying how BCGs grow in size, scientists gain insight into the formation and evolution of galaxies in general. ... When they examined the Hubble images, the team found that these distant BCGs are almost the same size as their nearby counterparts, and that these galaxies have grown at most by 30 percent in the past 9 billion years. ...