Lives of the First Stars

The first stars and galaxies were crucial in transforming an initially simple and relatively homogeneous universe into one of increasing complexity in structure and content. The very first stars began the chain of galaxy formation and set the stage for the evolution of the structure of the universe. These stars died out, for the most part in extremely energetic supernovae, billions of years ago, but their signatures remain in what followed. Professor Bromm and his group are attempting to understand the way in which the physics of early star birth and death influenced subsequent developments by simulating the first luminous objects in the universe. These first stars formed a few hundred million years after the Big Bang.

Bromm's simulations, which use a smoothed-particle hydrodynamics code (in which a fluid is represented as a collection of particles each carrying an appropriate amount of mass), attempt to answer the many open questions about the evolution of the first stars. How massive were they? How did they assemble into the first galaxies? When the stars died in giant explosions, what was the distribution of new elements produced from the primordial hydrogen and helium? How did the radiation produced by the first stars interact with the neutral atoms in the surrounding universe, and what were the properties of the material out of which the next generations of stars and galaxies formed? Together with his colleagues in the exciting field of cosmology, Bromm is pioneering a new picture of the history of the early universe in the first billion years of its existence.