Conference

Primodial magnetic fields are a potentially interesting origin for cosmic magnetism. Such fields can leave an interesting signal not only in the CMB temperature and polarization, but in structure at low redshift, contributing to the matter power spectrum and SZ effect at small scales. I will talk about the reasons for considering primordial fields, their origin and evolution, and how their observational consequences constrain their nature.

Over the coming decade, tiny fluctuations in temperature and polarization of the Cosmic Microwave Background (CMB) will be mapped with unprecedented resolution. The Planck Surveyor, the Atacama Cosmology Telescope (ACT), and the South Pole Telescope (SPT) are already making great advances. In a few years, high resolution polarization experiments, such as PolarBear, ACTPol, and SPTPol will be in full swing. While these new arc-minute resolution observations will continue to help constrain the physics of the early universe, they will also be unique in a new way - they will allow us to measure the gravitational lensing of the CMB, i.e., the deflection of CMB photons by intervening large scale structure. CMB lensing will probe the growth of structure over cosmic time, helping constrain the total mass of neutrinos and the behavior of dark energy. In the first part of the talk, I will review the recent progress made with ACT, a powerful tool with new capabilities. In the second part, I will discuss the scientific potential of the CMB lensing signal, and its various applications in cross-correlation with other datasets. Finally, I will discuss the upcoming polarized counterpart of ACT --- the ACTPol project, which will have sixteen times better mapping speed than ACT, and will be a premier CMB lensing experiment. I will describe our plans to extract different flavors of science from the ACTPol data, including the cross-correlations with optical lensing and galaxy surveys, such as SDSS, BOSS, DES and LSST.