A new method of measuring the cluster peculiar velocity power spectrum

TL;DR

This paper introduces a novel method for estimating the cluster peculiar velocity power spectrum using spatial correlations of the kinetic Sunyaev-Zeldovich flux, avoiding thermal measurements and minimizing systematic errors.

Contribution

The proposed approach leverages KSZ flux correlations, providing a more robust and potentially more accurate measurement of the velocity power spectrum compared to traditional methods.

Findings

Future large sky surveys could achieve ~10% accuracy in velocity power spectrum estimates.

The method's systematic errors are always sub-dominant to statistical errors across relevant scales and redshifts.

It does not require thermal SZ or X-ray temperature measurements.

Abstract

We propose to use spatial correlations of the kinetic Sunyaev-Zeldovich (KSZ) flux as an estimator of the peculiar velocity power spectrum. In contrast with conventional techniques, our new method does not require measurements of the thermal SZ signal or the X-ray temperature. Moreover, this method has the special advantage that the expected systematic errors are always sub-dominant to statistical errors on all scales and redshifts of interest. We show that future large sky coverage KSZ surveys may allow a peculiar velocity power spectrum estimates of an accuracy reaching ~10%.