Speaker
Description
LiteBIRD is an ISAS/JAXA strategic L-class mission to probe cosmic inflation and the cosmic history of the Universe through full-sky measurements of cosmic microwave background (CMB) polarization. Its design will allow an almost cosmic variance limited measurement of the E-mode power spectrum at large angular scales and a much tighter constraint on the optical depth of reionization $\tau$ compared to Planck. We forecast how LiteBIRD, in combination with Planck CMB data for the smaller angular scales, will improve the constraints on $\tau$ and the reionization history. We perform an MCMC analysis using two mock datasets with different reionization histories and assuming four different reionization models. We see that LiteBIRD can constrain $\sigma(\tau)$ approximately three times better than Planck, and constrain the parameters of more general reionization models. If the assumed reionization model does not fit well the mock data reionization history, the best-fit $\tau$ from LiteBIRD can be biased. Combining LiteBIRD with the Simons Observatory (SO) CMB small-scales, SO lensing and Baryon Acoustic Oscillations (BAO), we forecast how the tighter $\sigma(\tau)$ from LiteBIRD translates into an improved constraint on the sum of neutrino masses $\Sigma m_{\nu}$. We also see that assuming the wrong reionization model would bias not only $\tau$, but also $\Sigma m_{\nu}$.