Sunyaev-Zel'dovich predictions for the Planck Surveyor satellite using the Hubble Volume simulations

Abstract

We use the billion-particle Hubble Volume simulations to make statistical predictions for the distribution of galaxy clusters that will be observed by the Planck Surveyor satellite through their effect on the cosmic microwave background - the Sunyaev-Zel'dovich (SZ) effect. We utilize the lightcone data sets for both critical density (τCDM) and flat low-density (ΛCDM) cosmologies: a 'full-sky' survey out to z ∼ 0.5, two 'octant' data sets out to beyond z = 1, and a 100 square degree data set extending to z ∼ 4. Making simple, but robust, assumptions regarding both the thermodynamic state of the gas and the detection of objects against an unresolved background, we present the expected number of SZ sources as a function of redshift and angular size, and also as a function of flux (for both the thermal and kinetic effects) for three of the relevant High Frequency Instrument frequency channels. We confirm the expectation that the Planck Surveyor will detect around 5 × 104 clusters, though the exact number is sensitive to the choice of several parameters including the baryon fraction, and also to the cluster density profile, so that either cosmology may predict more clusters. We also find that the majority of detected sources should be at z < 1.5, and we estimate that around 1 per cent of clusters will be spatially resolved by the Planck Surveyor, though this has a large uncertainty.