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TAPIR Seminar

Friday, April 26, 2019
2:00pm to 3:00pm
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Cahill 370
The stellar local velocity distribution and its implications for dark matter
Lina Necib, Sherman Fairchild Postdoctoral Scholar in Theoretical Physics, High Energy Physics, Caltech,

Using two realizations of the Milky Way from the FIRE simulation, we find that the kinematics of dark matter follows closely the kinematics of accreted stars from the same mergers. We use this correspondence to obtain an empirical measurement of the local velocity distribution of dark matter by analyzing the Gaia second data release coupled with the ninth release from the Sloan Digital Sky Survey, and computing the velocity distribution of the accreted stars. We find that this velocity distribution is peaked at lower velocities than the generally assumed Maxwell Boltzmann distribution, due to the presence of a recent merger referred to as the Gaia Enceladus or the Gaia Sausage, leading to a weakening of direct detection limits at dark matter masses less than 10 GeV.

For more information, please contact JoAnn Boyd by phone at 4280 or by email at