Friday, October 5, 2012
2:00 pm
Cahill 370

TAPIR Seminar

Velocity and feedback enhance 21-cm signal from first stars at z ~ 20
Anastasia Fialkov, Tel Aviv University
In this talk I will show that first stars at z~20 leave detectable signature in the redshifted 21-cm line of neutral hydrogen. Two effects previously omitted in similar studies are responsible for a substantial enhancement in the expected signal: the relative motion between the dark matter halos and the in-falling gas, and the negative Lyman-Werner feedback of the starlight on star formation. I will shortly describe the underlying semi-numerical method, which combines linear evolution on large scales and application of analytical models and the results of small-scale numerical simulations on non-linear scales. Finally, I will explain how the two effects boost the power spectrum of the 21-cm signal thus making its detection easier.
Contact JoAnn Boyd joann@caltech.edu at 4280
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