A Projected Estimate of the Reionization Optical Depth Using the CLASS Experiment's Sample-Variance Limited E-Mode Measurement
Abstract
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 τ. We use a power spectrum-based likelihood to simultaneously clean foregrounds and estimate cosmological parameters in multipole space. Using software specifically designed to constrain τ, the amplitude of scalar fluctuations As, and the tensor-to-scalar ratio r, we demonstrate that the CLASS experiment will be able to estimate τ within a factor of two of the full-sky cosmic variance limit allowed by cosmic microwave background polarization measurements. Additionally, we discuss the role of CLASS's τ constraint in conjunction with gravitational lensing of the CMB on obtaining a 4σ measurement of the sum of the neutrino masses.