Institute for Advanced Study Astrophysics Seminar

ABSTRACT: Stacking of data from the Planck satellite allows the mean Sunyaev-Zeldovich decrement of dark matter halos to be measured over a range of more than two orders of magnitude in mass. Surprisingly, the results indicate that the amount of baryons present is close to the mean cosmic baryon fraction down to scales only slightly above that of our own Milky Way's halo. This corresponds to about a quarter of all the baryons in the low redshift universe.