Baryon Pasting Algorithm: Halo-based and Particle-based Pasting Methods
Résumé
We present a fast methodology to produce mock observations of the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects based on dark matter only $N$-body simulations coupled with the analytic intra-cluster medium model. The methods employ two different approaches: halo-based pasting (HP) and particle-based pasting (PP). The former pastes gas density and pressure onto halos and requires only halo catalogue, and the latter also considers contribution from field particles as well, i.e., particles which do not belong to any halos, and thus utilises the full particle information. Therefore, the PP algorithm incorporates secondary effects beyond the HP algorithm: asphericity of halos and contribution from diffuse gas. In particular, such diffuse component is the dominant source of the kinetic SZ effect. As validation of our methods, we have produced 108 all-sky maps with HP and 108 flat-sky maps which cover $5 \times 5 \, \mathrm{deg}^2$ with both of HP and PP. Our method can produce a mock map within a few hours even for all-sky coverage with parallel computational environment. The resultant power spectra of these maps are consistent with theoretical predictions. We discuss the utility of baryon pasted mock SZ maps for estimating the covariance matrix of cross-correlation between SZ effects and other large-scale structure probes as well as modelling the selection and projection effects for cluster cosmology.