Mitigating Foreground Bias to the CMB Lensing Power Spectrum for a CMB-HD Survey

Understand

A promising way to measure the distribution of matter on small scales (k ~ 10 hMpc^-1) is to use gravitational lensing of the Cosmic Microwave Background (CMB).

• CMB-HD, a proposed high-resolution, low-noise millimeter survey over half the sky, can measure the CMB lensing auto spectrum on such small scales enabling measurements that can distinguish between a cold dark matter (CDM) model and alternative models designed to solve problems with CDM on small scales.
• However, extragalactic foregrounds can bias the CMB lensing auto spectrum if left untreated.
• We present a foreground mitigation strategy that provides a path to reduce the bias from two of the most dominant foregrounds, the thermal Sunyaev-Zel'dovich effect (tSZ) and the Cosmic Infrared Background (CIB).