An Analytic Hybrid Halo + Perturbation Theory Model for Small-scale Correlators: Baryons, Halos, and Galaxies

TL;DR

This paper introduces an updated analytic model, HZPT, for small-scale clustering of dark matter, halos, and galaxies, achieving high accuracy and accounting for baryonic feedback, halo exclusion, and satellite effects.

Contribution

The paper develops an improved, analytic Halo Zeldovich Perturbation Theory model that accurately describes small-scale clustering and cross-correlations of matter, halos, and galaxies.

Findings

Model achieves 2% accuracy for matter and galaxy power spectra at relevant scales.

Incorporates effects of baryonic feedback and halo exclusion.

Provides a fast, interpretable tool for combined-probe analyses.

Abstract

We update Halo Zeldovich Perturbation Theory (HZPT), an analytic model for the two-point statistics of dark matter, to describe halo and galaxy clustering, and galaxy-matter cross-correlation on nonlinear scales. The model correcting Zeldovich has an analytic Fourier transform, and therefore is valid in both configuration space and Fourier space. The model is accurate at the $2\%$-level or less for $P_{mm}$ (k < 1 h/Mpc), $P_{hm}$ (k < 1 h/Mpc), $P_{hh}$ (k < 2 h/Mpc), $P_{gm}$ (k < 1 h/Mpc), $P_{gg}$ (k < 1 h/Mpc), $\xi_{mm}$ (r > 1 Mpc/h), $\xi_{hm}$ (r > 2 Mpc/h), $\xi_{hh}$ (r > 2 Mpc/h), $\xi_{gm}$ (r > 1 Mpc/h), $\xi_{gg}$ (r > 2 Mpc/h), for LRG-like mock galaxies. We show that the HZPT model for matter correlators can account for the effects of a wide range of baryonic feedback models and provide extended dark matter models which are of $1\% ~(3\%)$ accuracy for k < 10 (8) h/Mpc. We explicitly model the non-perturbative features of halo exclusion for the halo-halo and galaxy-galaxy correlators, as well as the presence of satellites for galaxy-matter and galaxy-galaxy correlation functions. We perform density estimation using N-body simulations and a wide range of HOD galaxy mocks to obtain correlations of model parameters with the cosmological parameters $\Omega_{m}$ and $\sigma_{8}$. HZPT can provide a fast, interpretable, and analytic model for combined-probe analyses of redshift surveys using scales well into the non-linear regime.