Blake Sherwin
(BCCP)
Towards a Clear View of the Early Universe: Methods for Delensing Near-Future CMB Polarization Surveys
Large-scale B-mode polarization is one of our most promising windows to probe the physics of inflation, and study the universe at the highest energies and earliest times. But this window's glass is blurred: gravitational lensing produces a background of non-primordial B-modes, which present a fundamental limit to constraints on inflationary B-mode polarization. After a brief review of CMB lensing science in general, I will discuss methods for getting around this limit by delensing the B-mode sky -- removing the non-primordial component by subtracting off an estimate of the lensing B-mode. In particular, I will discuss some recent work on delensing the CMB using the cosmic infrared background or CIB, the large scale structure tracer which is the closest known match to the true CMB lensing map. I will explain why delensing with the CIB is a promising method to enhance near-future B-mode surveys and strengthen the constraints on inflation they can provide.