Testing the WMAP cosmology via Planck radio catalogues

TL;DR

This study tests the WMAP beam profiles using Planck data and finds that beam systematics can significantly impact the interpretation of the CMB power spectrum and cosmological parameters.

Contribution

The paper provides new evidence that WMAP beam profiles are wider than expected and demonstrates the importance of beam systematics in cosmological analyses.

Findings

WMAP beam profiles appear wider than expected at Q, V, and W bands.

No evidence for a WMAP Sunyaev-Zel'dovich deficit.

Beam systematics can affect the amplitude and position of acoustic peaks.

Abstract

The prime evidence underpinning the standard LCDM cosmological model is the CMB power spectrum as observed by WMAP and other microwave experiments. But Sawangwit & Shanks (2010) 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, normalised either directly to the radio source profiles or using Planck fluxes. The same result is also found based on WMAP-CMBfree source catalogues and 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 ~3sigma 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 (2011) 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 ~0.1mK 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.