Taking measurements of the kinematic Sunyaev-Zel'dovich effect forward: including uncertainties from velocity reconstruction with forward modeling

TL;DR

This paper presents a novel measurement of the kinematic Sunyaev-Zel'dovich effect using Planck data, incorporating Bayesian forward modeling to account for velocity reconstruction uncertainties, leading to more accurate and unbiased results.

Contribution

It introduces a Bayesian forward modeling approach that explicitly includes velocity reconstruction uncertainties in kSZ measurements, improving accuracy over previous methods.

Findings

Detected kSZ signal at approximately 2 sigma significance.

Including uncertainties increases the measurement's uncertainty by about 15%.

Method sets the stage for future high-resolution CMB analyses to better constrain baryonic content.

Abstract

We measure the kinematic Sunyaev-Zel'dovich (kSZ) effect, imprinted by maxBCG clusters, on the Planck SMICA map of the Cosmic Microwave Background (CMB). Our measurement, for the first time, directly accounts for uncertainties in the velocity reconstruction step through the process of Bayesian forward modeling. We show that this often neglected uncertainty budget typically increases the final uncertainty on the measured kSZ signal amplitude by $\simeq15\%$ at cluster scale. We observe evidence for the kSZ effect, at a significance of $\simeq2\sigma$. Our analysis, when applied to future higher-resolution CMB data, together with minor improvements in map-filtering and signal-modeling methods, should yield both significant and unbiased measurements of the kSZ signal, which can then be used to probe and constrain baryonic content of galaxy clusters and galaxy groups.