Maximum likelihood kinetic Sunyaev Zel'dovich velocity reconstruction

Abstract

The kinetic Sunyaev Zel'dovich (kSZ) effect, cosmic microwave background (CMB) temperature anisotropies induced by the scattering of CMB photons from free electrons, will be measured by near-term CMB experiments at high significance. By combining CMB temperature anisotropies with a tracer of structure, such as a galaxy redshift survey, previous literature introduced a number of techniques to reconstruct the radial velocity field. This reconstructed radial velocity field encapsulates the majority of the cosmological information contained in the kSZ temperature anisotropies, and can provide powerful new tests of the standard cosmological model and theories beyond it. In this paper, we introduce a new estimator for the radial velocity field based on a coarse-grained maximum likelihood fit for the kSZ component of the temperature anisotropies, given a tracer of the optical depth. We demonstrate that this maximum likelihood estimator yields a higher fidelity reconstruction than existing quadratic estimators in the low-noise and high-resolution regime targeted by upcoming CMB experiments. We describe implementations of the maximum likelihood estimator in both harmonic space and map space, using either direct measurements of the optical depth field or a galaxy survey as a tracer. We comment briefly on the impact of biases introduced by imperfect reconstruction of the optical depth field.

23 pages with 5 figures; comments welcome

References in corpus (17)

• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• Halo Models of Large Scale Structure
• The Simons Observatory: Science goals and forecasts
• The Tau of Galaxy Clusters
• Cosmology with kSZ: breaking the optical depth degeneracy with Fast Radio Bursts
• Reconstruction of the remote dipole and quadrupole fields from the kinetic Sunyaev Zel'dovich and polarized Sunyaev Zel'dovich effects
• Transverse Velocities with the Moving Lens Effect
• Polarized Sunyaev Zel'dovich tomography
• Planck intermediate results. LVI. Detection of the CMB dipole through modulation of the thermal Sunyaev-Zeldovich effect: Eppur si muove II
• Cosmology with the moving lens effect
• Analyzing the cosmic variance limit of remote dipole measurements of the cosmic microwave background using the large-scale kinetic Sunyaev Zel'dovich effect
• Exploring KSZ velocity reconstruction with $N$-body simulations and the halo model
• Improving Small-Scale CMB Lensing Reconstruction
• Reconstructing large scales at cosmic dawn
• Simulated reconstruction of the remote dipole field using the kinetic Sunyaev Zel'dovich effect
• Teaching neural networks to generate Fast Sunyaev Zel'dovich Maps
• Remote Dipole Field Reconstruction with Dusty Galaxies

Cited by in corpus (1)

• Projected-Field Kinetic Sunyaev-Zel'dovich Cross-Correlations: Halo Model and Forecasts