Physics Colloquium: Detecting the First Stars from just 200 Million Years after the Big Bang

Abstract:

Understanding the formation and evolution of the first stars and galaxies is one of the exciting frontiers in astronomy. Since the universe was filled with neutral hydrogen at early times, the most promising method for observing the epoch of the first stars is using the prominent 21-cm spectral line of hydrogen. Current observational efforts are focused on a cosmic age of 500 million years, with earlier times considered much more challenging. We show that stars from a much earlier era may be observable as a result of a recently noticed effect of different motions of the dark matter and the ordinary matter in the early universe. We produce simulated maps of the first stars and show that these relative motions significantly enhance large-scale fluctuations and produce prominent structure on the scale of a degree in the 21-cm intensity distribution. The particular form expected for this structure should make it easier to confirm the existence of million solar-mass halos at early times.

Seminar Organisers: Dr. Tomer Volansky, Dr. Dovi Poznanski