Wednesday, March 27, 2013
Cahill, Hameetman Auditorium
Detecting the First Stars at Redshift 20:
Rennan Barkana, Tel Aviv
Understanding the formation and evolution of the first stars andgalaxies is one of the most 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 baryons 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 signature of this structure
should make it easier to confirm the existence of million solar-mass halos at early times.