The phrase "dim galaxies" refers to galaxies that are not very bright or glowing. They are not easily seen or noticed because they lack strong and visible light. Full definition
The number of dim galaxies they observed is roughly equivalent to the number of normal galaxies in the same region of space. (discovermagazine.com)
BUG EYES The multi-lensed Dragonfly telescope (shown) in New Mexico has triggered a hunt for dim galaxies in our cosmic neighborhood. (sciencenews.org)
According to recent studies, dim galaxies like those strangely hardy ones in Coma look to be almost entirely made of the stuff. (discovermagazine.com)