Noun
protogalaxy (plural protogalaxies)
A cloud of gas which is starting to form a galaxy.
Hot dark matter main "Hot" dark matter consists of particles whose FSL is much larger than the size of a protogalaxy. Source: Internet
It is dark matter composed of constituents with an FSL much smaller than a protogalaxy. Source: Internet
Warm dark matter main "Warm" dark matter refers to particles with an FSL comparable to the size of a protogalaxy. Source: Internet
Conversely, much lighter particles, such as neutrinos with masses of only a few eV, have FSLs much larger than a protogalaxy, thus qualifying them as "hot". Source: Internet