Exploring KSZ velocity reconstruction with $N$-body simulations and the halo model

Understand

KSZ velocity reconstruction is a recently proposed method for mapping the largest-scale modes of the universe, by applying a quadratic estimator $\hat{v}_r$ to the small-scale CMB and a galaxy catalog.

• We implement kSZ velocity reconstruction in an $N$-body simulation pipeline and explore its properties.
• We find that the reconstruction noise can be larger than the analytic prediction which is usually assumed.
• We revisit the analytic prediction and find additional noise terms which explain the discrepancy.