Mariska Kriek

Harvard Smithsonian Center for Astrophysics

The Life Cycle of Massive Galaxies

Similar to the situation at low redshift, the properties of galaxies beyond z = 2 are strongly correlated. Massive galaxies at this epoch clearly separate into two classes: the large star-forming galaxies that form the blue cloud, and the smaller quiescent galaxies on the red sequence. Thus, it is evident that a Hubble sequence with strongly correlated galaxy properties is already in place beyond z = 2. Nonetheless, this sequence does not resemble the local Hubble sequence, as the structures and morphologies of the z > 2 galaxies are different from those of their local analogs. While quiescent galaxies are much more compact than nearby early-type galaxies, massive star-forming galaxies have irregular and clumpy structures. This raises the question of how this sequence originated, and subsequently evolves into the galaxy population that we find in the present-day universe. In this talk I will present our latest results and discuss the implications for the formation histories of massive galaxies.