Measuring the Largest Angular Scale CMB B-mode Polarization with Galactic Foregrounds on a Cut Sky

Understand

We consider the effectiveness of foreground cleaning in the recovery of Cosmic Microwave Background (CMB) polarization sourced by gravitational waves for tensor-to-scalar ratios in the range $0<r<0.1$.

• Using the planned survey area, frequency bands, and sensitivity of the Cosmology Large Angular Scale Surveyor (CLASS), we simulate maps of Stokes $Q$ and $U$ parameters at 40, 90, 150, and 220 GHz, including realistic models of the CMB, diffuse Galactic thermal dust and synchrotron foregrounds, and Gaussian white noise.
• We use linear combinations (LCs) of the simulated multifrequency data to obtain maximum likelihood estimates of $r$, the relative scalar amplitude $s$, and LC coefficients.
• We find that for 10,000 simulations of a CLASS-like experiment using only measurements of the reionization peak ($\ell\leq23$), there is a 95% C.L.