tracing dark matter with old stars

The research highlight of a low-research Tuesday was an absolutely great talk by Lina Necib (Caltech), who is looking at empirical methods for understanding the velocity distribution of dark matter in the local volume. Why? Because dark-matter detection experiments depend on it. How? By using an old (but rarely executed) idea that low-metallicity stars, being very old, ought to trace (at least some component of) the dark matter. This method of finding the dark matter is assumption-laden, but so are all the theoretical approaches. It is exciting (for me) to see an empirical approach. Indeed, she finds a lower velocity dispersion than the standard value used in the business; this weakens some of the current experimental limits. It's also a great use of the Gaia and RAVE data.