Applied Physics/Physics Colloquium

Searching for the First Stars
Tuesday, May 12, 2015 - 4:00pm to 5:00pm
Hewlett 201
Harvey Moseley (NASA)
Abstract / Description: 

Through observations of the CMB, we have a clear picture of the conditions in the universe at the point where atoms first combined and the universe became transparent. From deep observations of galaxies, we can study the universe at a z of ~ 6. Here, we find galaxies, smaller and more irregular than in our local universe, but recognizable as galaxies. In the critical period between recombination and z~6, the first stars and galaxies were born. Their radiation reionized the universe, and their nucleosynthetic products contaminated the interstellar matter from which later generations of stars would form with heavy elements. I will review the investigations that have searched for the diffuse light from this epoch, starting with total power observations such as those done by DIRBE on COBE to more recent observations of spatial correlations by the GSFC, Akiri, Irvine, and Caltech groups. There has been rapid progress in this research. Spatial correlations between the near IR emission and Chandra soft X-ray emission suggests an origin in energetic systems, while large scale spatial correlations seen in the near IR suggest an origin in stars stripped from galaxies. The next years will see these conflicts resolved and may reveal a first clear view into the concealed early history of the universe.