2019/09/07 by Hung, Johnathan, Manera, Marc, Shellard, E. P. S.
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.1909.03248
We investigate various phenomenological schemes for the rapid generation of 3D mock galaxy catalogues with a given power spectrum and bispectrum. We apply the fast bispectrum estimator \MODALLSS to these mock galaxy catalogues and compare to N-body simulation data analysed with the halo-finder ROCKSTAR (our benchmark data). We propose an assembly bias model for populating parent halos with subhalos by using a joint lognormal-Gaussian probability distribution for the subhalo occupation number and the halo concentration. This prescription enabled us to recover the benchmark power spectrum from N-body simulations to within 1% and the bispectrum to within 4% across the entire range of scales of the simulation. A small further boost adding an extra galaxy to all parent halos above the mass threshold M>2×1014 h-1 M_\odot obtained a better than 1% fit to both power spectrum and bispectrum in the range K/3<1.1 h Mpc-1, where K=k1+k2+k3. This statistical model should be applicable to fast dark matter codes, allowing rapid generation of mock catalogues which simultaneously reproduce the halo power spectrum and bispectrum obtained from N-body simulations. We also investigate alternative schemes using the Halo Occupation Distribution (HOD) which depend only on halo mass, but these yield results deficient in both the power spectrum (2%) and the bispectrum (>4%) at k,K/3 ≈ 0.2 h Mpc-1, with poor scaling for the latter. Efforts to match the power spectrum by modifying the standard four-parameter HOD model result in overboosting the bispectrum (with a 10% excess). We also characterise the effect of changing the halo profile on the power spectrum and bispectrum.