The First Stars and Galaxies in the Universe

John Wise (Georgia Tech) - April 3, 2017 at 12:10 pm

Cosmic structure forms hierarchically through smooth accretion and dark matter halo mergers. As a consequence, all galaxies are the product of the dozens of mergers over billions of years. However, one can ask, "What were the first stars and galaxies in the universe?" I will review the current state-of-the-art simulations of early galaxy formation, starting with the formation of the first stars, which are initially devoid of metals and are suggested to have a characteristic mass of tens of solar masses. I will then present results from a suite of cosmological radiation hydrodynamics simulations that focus on the transition from the first stars to the first galaxies. Each simulation captures the radiative and chemical feedback from 10,000 first stars, leading to the formation of a 10^8 solar mass galaxy only 500 million years after the Big Bang, which is detectable with the upcoming James Webb Space Telescope. We have found that the galaxy luminosity function flattens at UV magnitudes above -14 due to feedback effects, and I will present theoretical predictions for their photometry and effects from dust extinction. I will also demonstrate that these faintest galaxies are the primary driver of the reionization of the universe, only to be suppressed by photo-heating at later times, perhaps evolving into a subset of dwarf galaxies in the local universe.

The seminar will be held in 131A Campbell Hall.

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