Testing WMAP data via Planck radio and SZ catalogues

Abstract

The prime evidence underpinning the standard Λ cold dark matter cosmological model is the cosmic microwave background (CMB) power spectrum as observed by Wilkinson Microwave Anisotropy Probe (WMAP) and other microwave experiments. But Sawangwit and Shanks have recently shown that the WMAP CMB power spectrum is highly sensitive to the beam profile of the WMAP telescope. Here, we use the source catalogue from the Planck early data release to test further the WMAP beam profiles. We confirm that stacked beam profiles at Q, V and particularly at W, appear wider than expected when compared to the Jupiter beam, normalized either directly to the radio source profiles or using Planck fluxes. The same result is also found based on WMAP-CMB-free source catalogues and NRAO VLA Sky Survey (NVSS) sources. The accuracy of our beam profile measurements is supported by analysis of CMB sky simulations. However, the beam profiles from WMAP7 at the W band are narrower than previously found in WMAP5 data and the rejection of the WMAP beam is now only at the ≈3σ level. We also find that the WMAP source fluxes demonstrate possible non-linearity with Planck fluxes. But including ground-based and Planck data for the bright Weiland et al. sources may suggest that the discrepancy is a linear offset rather than a non-linearity. Additionally, we find that the stacked Sunyaev–Zel'dovich (SZ) decrements of ≈151 galaxy clusters observed by Planck are in agreement with the WMAP data. We find that there is no evidence for a WMAP SZ deficit as has previously been reported. In the particular case of Coma, we find evidence for the presence of an |$\mathcal {O}(0.1\,{\rm mK})$| downwards CMB fluctuation. We conclude that beam profile systematics can have significant effects on both the amplitude and position of the acoustic peaks, with potentially important implications for cosmology parameter fitting.