The MICE Grand Challenge Lightcone Simulation II: Halo and Galaxy catalogues

TL;DR

<3-5 sentence high-level summary> The paper presents the MICE Grand Challenge lightcone, delivering halo and galaxy catalogues derived from a massive N-body simulation designed to capture large-volume structure with high mass resolution. It introduces a hybrid HOD+HAM scheme to populate halos with galaxies, validates mass functions and clustering against theoretical fits and observations, and analyzes bias and redshift-space distortions from small to BAO scales. The study quantifies mass-resolution effects on halo bias, characterizes scale-dependent bias for halos and galaxies, and demonstrates the Kaiser limit's applicability while highlighting satellite-driven departures. A public release of the MICECAT v1.0 catalogues provides a valuable tool for survey design, BAO/ruler tests, and RSD analyses in the era of precision cosmology.

Abstract

This is the second in a series of three papers in which we present an end-to-end simulation from the MICE collaboration, the MICE Grand Challenge (MICE-GC) run. The N-body contains about 70 billion dark-matter particles in a $(3 \, h^{-1} \, {\rm Gpc})^3$ comoving volume spanning 5 orders of magnitude in dynamical range. Here we introduce the halo and galaxy catalogues built upon it, both in a wide ($5000 \,{\rm deg}^2$) and deep ($z<1.4$) light-cone and in several comoving snapshots. Halos were resolved down to few $10^{11} \,h^{-1}\,{\rm M_{\odot}}$. This allowed us to model galaxies down to absolute magnitude M$_r<-18.9$. We used a new hybrid Halo Occupation Distribution and Abundance Matching technique for galaxy assignment. The catalogue includes the Spectral Energy Distributions of all galaxies. We describe a variety of halo and galaxy clustering applications. We discuss how mass resolution effects can bias the large scale $2$-pt clustering amplitude of poorly resolved halos at the $\lesssim 5\%$ level, and their $3$-pt correlation function. We find a characteristic scale dependent bias of $\lesssim 6\%$ across the BAO feature for halos well above $M_{\star}\sim 10^{12}\,h^{-1}\,{\rm M_{\odot}}$ and for LRG like galaxies. For halos well below $M_{\star}$ the scale dependence at $100\,{\rm Mpc} h^{-1}$ is $\lesssim 2\%$. Lastly we discuss the validity of the large-scale Kaiser limit across redshift and departures from it towards nonlinear scales. We make the current version of the light-cone halo and galaxy catalogue (MICECATv1.0) publicly available through a dedicated web portal, http://cosmohub.pic.es, to help develop and exploit the new generation of astronomical surveys.

Figures (21)

• Figure 1: Mass Function in MICE at $z=0$. Black symbols show the halo abundance in the Grand Challenge run while red symbols correspond to the intermediate simulation with the same cosmology but 8 times worse mass resolution ($m_p = 2.9 \times 10^{10} \,h^{-1}\,{\rm M_{\odot}}$ vs. $m_p = 2.3 \times 10^{11} \,h^{-1}\,{\rm M_{\odot}}$). The dashed line results from a fit to a series of MICE simulations (Crocce et al. 2010). Abundances are depicted relative to the Sheth and Tormen model and error-bars were estimated using jack-knife resampling.
• Figure 2: Cumulative mass function measured in MICE-GC down to the extreme regime of poorly resolved halos with 10 or more particles. The inset panel show the ratio to the prediction for this quantity using the fit from Crocce et al. (2010), which is depicted by a solid green line in the main panel.
• Figure 3: Halo abundance as a function of redshift in the MICE-GC lightcone for several consecutive redshift bins. The theory model shown, from Crocce et al. 2010, does not assume universality.
• Figure 4: Large-scale halo and galaxy (auto) power spectrum in the MICE-GC comoving output at $z=0$ (over a smooth broad-band power, without shot-noise correction). We display three self corresponding magnitude and mass threshold samples. For a given halo mass threshold we select the corresponding magnitude limited galaxy sample from the mean "halo mass - central galaxy luminosity" relation. We then consider both "centrals only" or "central+satellites" in each sample. The dashed black line corresponds to the clustering of dark matter. The figure shows that the large volume and good mass-resolution in MICE-GC allows to study large-scale clustering from anti-biased or un-biased samples to highly biased ones, with percent level error-bars at BAO scales. In addition notice how in general satellite galaxies increase the clustering amplitude above the "centrals only" without introducing noticeable extra scale-dependence.
• Figure 5: Symbols show the 2-point correlation function $\xi(r)$ (scaled by $r^2$) in FoF halos (with 20-50 particles) for three redshift bins in the lightcone (in real space). Dashed lines are the corresponding DM smoothed linear theory predictions (which resemble non-linear predictions). Notice how halo biasing for constant mass is roughly degenerate with growth, yielding a constant clustering amplitude.