The MillenniumTNG Project: Refining the one-halo model of red and blue galaxies at different redshifts

Abstract

Luminous red galaxies (LRGs) and blue star-forming emission-line galaxies (ELGs) are key tracers of large-scale structure used by cosmological surveys. Theoretical predictions for such data are often done via simplistic models for the galaxy-halo connection. In this work, we use the large, high-fidelity hydrodynamical simulation of the MillenniumTNG project (MTNG) to inform a new phenomenological approach for obtaining an accurate and flexible galaxy-halo model on small scales. Our aim is to study LRGs and ELGs at two distinct epochs, $z=1$ and $z=0$, and recover their clustering down to very small scales, $r\sim 0.1\mathrm{Mpc}/h$, i.e. the one-halo regime, while a companion paper extends this to a two-halo model for larger distances. The occupation statistics of ELGs in MTNG inform us that: (1) the satellite occupations exhibit a slightly super-Poisson distribution, contrary to commonly made assumptions, and (2) that haloes containing at least one ELG satellite are twice as likely to host a central ELG. We propose simple recipes for modeling these effects, each of which calls for the addition of a single free parameter to simpler halo occupation models. To construct a reliable satellite population model, we explore the LRG and ELG satellite radial and velocity distributions and compare them with those of subhalos and particles in the simulation. We find that ELGs are anisotropically distributed within halos, which together with our occupation results provides strong evidence for cooperative galaxy formation (manifesting itself as one-halo galaxy conformity); i.e.~galaxies with similar properties form in close proximity to each other. Our refined galaxy-halo model represents a useful improvement of commonly used analysis tools and thus can be of help to increase the constraining power of large-scale structure surveys.

14 pages, 10 figures; submitted to MNRAS

References in corpus (14)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Properties of galaxies reproduced by a hydrodynamic simulation
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• The DESI Experiment Part I: Science,Targeting, and Survey Design
• Wide-Field InfrarRed Survey Telescope-Astrophysics Focused Telescope Assets WFIRST-AFTA 2015 Report
• Simulating cosmic structure formation with the GADGET-4 code
• Introducing the THESAN project: radiation-magnetohydrodynamic simulations of the epoch of reionization
• Lensing is Low: Cosmology, Galaxy Formation, or New Physics?
• Corrfunc --- A Suite of Blazing Fast Correlation Functions on the CPU
• The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: exploring the Halo Occupation Distribution model for Emission Line Galaxies
• \textsc{CompaSO}: A new halo finder for competitive assignment to spherical overdensities
• The galaxy-halo connection of emission-line galaxies in IllustrisTNG
• Extensions to models of the galaxy-halo connection
• Galactic Conformity in both Star-formation and Morphological Properties

Cited by in corpus (9)

• The MillenniumTNG Project: The impact of baryons and massive neutrinos on high-resolution weak gravitational lensing convergence maps
• Learning to Concentrate: Multi-tracer Forecasts on Local Primordial Non-Gaussianity with Machine-Learned Bias
• The MillenniumTNG Project: Semi-analytic galaxy formation models on the past lightcone
• HOD-Dependent Systematics in Emission Line Galaxies for the DESI 2024 BAO analysis
• The impact of baryons on the internal structure of dark matter haloes from dwarf galaxies to superclusters in the redshift range 0<z<7
• Investigating the galaxy-halo connection of DESI Emission-Line Galaxies with SHAMe-SF
• Dark from light (DfL): Inferring halo properties from luminous tracers with machine learning trained on cosmological simulations. I. Method, proof of concept & preliminary testing
• Differences in baryonic and dark matter scaling relations of galaxy clusters: A comparison between IllustrisTNG simulations and observations
• Fast Baryonic Field Painting for Sunyaev-Zel'dovich Analyses: Transfer Function vs. Hybrid Effective Field Theory