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

摘要

We analyze simulated maps of the Cosmology Large Angular Scale Surveyor(CLASS) experiment and recover a nearly cosmic-variance limited estimate of thereionization optical depth $\tau$. We use a power spectrum-based likelihood tosimultaneously clean foregrounds and estimate cosmological parameters inmultipole space. Using software specifically designed to constrain $\tau$, theamplitude of scalar fluctuations $A_s$, and the tensor-to-scalar ratio $r$, wedemonstrate that the CLASS experiment will be able to estimate $\tau$ within afactor of two of the full-sky cosmic variance limit allowed by cosmic microwavebackground polarization measurements. Additionally, we discuss the role ofCLASS's $\tau$ constraint in conjunction with gravitational lensing of the CMBon obtaining a $\gtrsim4\sigma$ measurement of the sum of the neutrino masses.