Planck Intermediate Results. V. Pressure profiles of galaxy clusters from the Sunyaev-Zeldovich effect. (arXiv:1207.4061v1 [astro-ph.CO])

Planck Intermediate Results. V. Pressure profiles of galaxy clusters from the Sunyaev-Zeldovich effect. (arXiv:1207.4061v1 [astro-ph.CO]):
Taking advantage of the all-sky coverage and broad frequency range of the
Planck satellite, we study the Sunyaev-Zeldovich (SZ) and pressure profiles of
62 nearby massive clusters detected at high significance in the 14-month
nominal survey. Careful reconstruction of the SZ signal indicates that most
clusters are individually detected at least out to R500. By stacking the radial
profiles, we have statistically detected the radial SZ signal out to 3R500,
i.e., at a density contrast of about 50-100, though the dispersion about the
mean profile dominates the statistical errors across the whole radial range.
Our measurement is fully consistent with previous Planck results on integrated
SZ fluxes, further strengthening the agreement between SZ and X-ray
measurements inside R500. Correcting for the effects of the Planck beam, we
have calculated the corresponding pressure profiles. This new constraint from
SZ measurements is consistent with the X-ray constraints from xmm in the region
in which the profiles overlap (i.e., [0.1-1] R500), and is in fairly good
agreement with theoretical predictions within the expected dispersion. At
larger radii the average pressure profile is shallower than the predictions.
Combining the SZ and X-ray observed profiles into a joint fit to a generalised
pressure profile gives best-fit parameters [P0, c500, gamma, alpha, beta] =
[6.41, 1.81, 0.31, 1.33, 4.13]. Using a reasonable hypothesis for the gas
temperature in the cluster outskirts we reconstruct from our stacked pressure
profile the gas mass fraction profile out to 3R500. Within the temperature
driven uncertainties, our Planck constraints are compatible with the cosmic
baryon fraction and expected gas fraction in halos.