KSZ Velocity Reconstruction with ACT and DESI-LS using a Tomographic QML Power Spectrum Estimator

TL;DR

This paper presents a novel quadratic maximum likelihood method for reconstructing kSZ velocities from ACT and DESI-LS data, achieving a significant detection and providing insights into feedback processes in halos.

Contribution

It introduces a new QML power spectrum estimator in redshift space for kSZ velocity reconstruction, demonstrating its effectiveness on real survey data.

Findings

Detected kSZ signal at 11.7 sigma significance.

Estimated kSZ amplitude of 0.39 ± 0.04, indicating high feedback.

Validated the QML pipeline's feasibility for future high-resolution surveys.

Abstract

We perform kinetic Sunyaev-Zel'dovich (kSZ) velocity reconstruction on data from ACT DR6 and DESI-LS DR9. To estimate the cross-power between kSZ velocity reconstruction and galaxy density, we make use of a novel quadratic maximum likelihood QML power spectrum estimator implementation in red-shift binned spherical coordinates. We find a detection of the kSZ signal from the cross-correlation between the estimated velocity field and the large-scale galaxy field of $11.7 \sigma$. We estimate an amplitude $A=0.39 \pm 0.04$ of the kSZ signal with respect to a halo model prediction, possibly indicating a high feedback in massive halos, in agreement with previous studies. Our result demonstrates the feasibility of an optimal QML pipeline at the resolution required for this analysis, and will be a powerful tool for kSZ cosmology with upcoming high-resolution surveys.