A Projected Estimate of the Reionization Optical Depth Using the CLASS Experiment's Sample Variance Limited E-mode Measurement

We analyze simulated maps of the Cosmology Large Angular Scale Surveyor (CLASS) experiment and recover a nearly cosmic variance limited estimate of the reionization optical depth tau. We use a power spectrum-based likelihood to simultaneously clean foregrounds and estimate cosmological parameters in multipole space. Using software specifically designed to constrain tau, the amplitude of scalar fluctuations A(s), and the tensor-to-scalar ratio r, we demonstrate that the CLASS experiment will be able to estimate tau within a factor of two of the cosmic variance limit allowed by full-sky cosmic microwave background polarization measurements. Additionally, we discuss the role of CLASS's tau constraint in conjunction with gravitational lensing of the CMB on obtaining a greater than or similar to 4 sigma measurement of the sum of the neutrino masses.