Institute for Advanced Study Informal Astrophysics Seminar

Paleoclimatological evidence suggests that the total gravitating mass density at the galactic plane is about twice the baryonic density. I will discuss this measurement and show that it is consistent with the different determinations of the local and column densities of both the baryonic and total mass, including the seemingly inconsistent kinematically determined local mass density, which due to spiral arm passages has a systematic offset. When all the data is combined we find evidence for dark matter having a local density of about 0.1 Msun/pc^3, and a column density of about 10 to 20 Msun/pc^2. I will also show that a cooling dark matter component is theoretically predicted to be able to cool to roughly this local density but not any denser.