A new method of measuring the cluster peculiar velocity power spectrum
  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%. 
Pengjie Zhang (Shanghai), Hume A. Feldman (Kansas), Roman Juszkiewicz   (Copernicus) and Albert Stebbins (Fermilab)