Lyman alpha nebula
Fr.: nébuleuse Lyman alpha
A huge gaseous nebula (≥ 50 kpc) lying at high → redshifts (z ~ 2-6) and strongly emitting radiation due to the → Lyman alpha line (luminosities of ≥ 1043 erg s-1) of hydrogen gas. Also called Lyman alpha blobs, they are thought to lie in massive (M ~ 1013 solar masses) → dark matter halos, which would subsequently evolve into those typical of rich → galactic clusters.