Peak exclusion, stochasticity and convergence of perturbative bias expansions in 1+1 gravity

• Published in: Monthly notices of the Royal Astronomical Society Vol. 456; no. 4; pp. 3985 - 4000
• Main Authors: Baldauf, Tobias, Codis, Sandrine, Desjacques, Vincent, Pichon, Christophe
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 11.03.2016; Oxford University Press (OUP): Policy P - Oxford Open Option A
• Subjects: Approximation; Astrophysics; Bias; Clustering; Dark matter; Deviation; Evolution; Gravitation; Gravity; Mathematical analysis; Mathematical models; Poisson distribution; Sciences of the Universe; Stochastic models; Tracers; methods: analytical; galaxies: statistics; large-scale structure of Universe
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stv2973

The Lagrangian peaks of a 1D cosmological random field representing dark matter are used as a proxy for a catalogue of biased tracers in order to investigate the small-scale exclusion in the two-halo term. The two-point correlation function of peaks of a given height is numerically estimated and analytical approximations that are valid inside the exclusion zone are derived. The resulting power spectrum of these tracers is investigated and shows clear deviations from Poisson noise at low frequencies. On large scales, the convergence of a perturbative bias expansion is discussed. Finally, we go beyond Gaussian statistics for the initial conditions and investigate the subsequent evolution of the two-point clustering of peaks through their Zel'dovich ballistic displacement, to clarify how exclusion effects mix up with scale-dependences induced by non-linear gravitational evolution. While the expected large-scale separation limit is recovered, significant deviations are found in the exclusion zone that tends in particular to be reduced at later times. Even though these findings apply to the clustering of 1D tracers, they provide useful insights into halo exclusion and its impact on the two-halo term.