All-sky component separation for the Planck mission

A harmonic-space maximum-entropy method (MEM) is presented for separating the emission from different physical components in all-sky observations by the forthcoming Planck satellite. The analysis is performed at full Planck resolution, with a pixel size of 1.7 arcmin, which corresponds to ℓmax≈ 6000. The simulated Planck data include emission from the cosmic microwave background (CMB), the kinetic and thermal Sunyaev–Zel'dovich (SZ) effects from galaxy clusters, as well as Galactic dust, free–free and synchrotron emission. Our simulations also assume homogeneous, uncorrelated pixel noise, although this is not a requirement of the method. We find that the MEM technique produces faithful reconstructions of the main input components over the whole sky, without the need to perform a Galactic cut. The CMB power spectrum is accurately recovered up to ℓ≈ 2000. The algorithm is parallelized so that the entire reconstruction can be performed in ∼6 h using 30 R10000 processors on an SGI Origin 2000 supercomputer and requires 14 Gb of RAM.