A Deep View on the Early Universe: Extreme Makeovers and Overweight Galaxies

Galaxies are the building blocks of the Universe; massive structures that contain up to 1000s of billions of stars. Galaxies in today's Universe show a striking diversity among their properties, with large variations in their appearance, age, size, weight, and stellar birth rate. Despite this diversity, galaxies can broadly be divided into two types: low-mass spiral galaxies with high stellar production rates, and massive old elliptical galaxies in which no new stars are being formed. Whereas this broad distinction was already recognized by Edwin Hubble in the 1920s, it has remained a puzzle as to how this dichotomy originated. In particular, the elliptical galaxy population poses great challenges, as we do not understand why these galaxies form no stars in a Universe with plenty of fuel. In order to explain their enormous number of stars, we know that their stellar birth rates must have been high in the past, after which some process halted the formation of new stars. Fortunately, the finite speed of light offers us a direct view of the distant pasts of galaxies. Galaxies have been observed over most of the history of the Universe, as early as 0.5 billion years after the Big Bang. In this talk, Kriek will present recent studies of galaxies in the Early Universe, and discuss our current view of how different types of galaxies may have formed and evolved over cosmic time.

Speaker: Mariska Kriek, UC Berkeley