Beyond its primary fluctuations, the cosmic microwave background (CMB) contains a wealth of information on the large-scale structure of the universe, which it illuminates as a backlight. The baryon momentum field is thus imprinted on the CMB through the kinematic Sunyaev-Zel'dovich (kSZ) effect. Current small-scale high-sensitivity CMB experiments make this effect detectable, providing a unique handle on peculiar velocities and baryon physics.
I will report a significant detection of the kSZ effect, obtained by combining CMB intensity data with peculiar velocities reconstructed from the galaxy number density field. I will present the prospects for localizing the missing baryons, constraining baryon physics inside galaxy clusters, and measuring the growth rate of structure from the kSZ effect. I will finally explore the possibility of measuring velocities across the line of sight through the CMB moving lens effect.
I will describe a novel method for simulating nonlinear structure formation in cosmologies that have hot or warm collisionless species. After introducing the method, I will show results of our simulations for universes with massive neutrinos, and warm dark matter simulations.