Our understanding of the redshift z>3 galaxy population relies largely on samples selected using the popular “dropout” technique, typically consisting of UV-bright galaxies with blue colors and prominent Lyman breaks. As it is currently unknown if these galaxies are representative of the massive galaxy population, we here use the FourStar Galaxy Evolution (ZFOURGE) Survey to create a stellar mass-limited sample at z = 3-4.
We find a diverse population: 45% of the massive galaxies are old/quiescent, 54% are dusty star-forming galaxies, and only 14% resemble luminous blue star forming Lyman break galaxies. This study clearly demonstrates an inherent diversity among massive galaxies at higher redshift than previously known.
Hubble Space Telescope (images F814W F125W F160W filters) of 9 galaxies located at redshifts z=3-4, or about 11.5 billion light years distant. We found that these massive galaxies were made up of 3 types: old (left column), young (middle) and dusty (right).