Minimizing gravitational lensing contributions to the primordial bispectrum covariance

Understand

The next generation of ground-based CMB experiments aim to measure temperature and polarization fluctuations up to $\ell_{\rm max} \approx 5000$ over half of the sky.

• Combined with Planck data on large scales, this will provide improved constraints on primordial non-Gaussianity.
• However, the impressive resolution of these experiments will come at a price.
• Besides signal confusion from galactic foregrounds, extra-galactic foregrounds and late-time gravitational effects, gravitational lensing will introduce large non-Gaussianity that can become the leading contribution to the bispectrum covariance through the connected 4-point function.