The MillenniumTNG Project: The large-scale clustering of galaxies

TL;DR

This paper introduces the MillenniumTNG simulation, a large-volume hydrodynamical model that accurately reproduces galaxy clustering and large-scale structure, aiding future galaxy survey analyses.

Contribution

The MillenniumTNG simulation is the largest hydrodynamical simulation to date, enabling detailed studies of galaxy clustering and bias on large scales.

Findings

MTNG accurately reproduces observed galaxy clustering as a function of stellar mass.

Significant scale-dependent bias is observed on scales smaller than 10 Mpc.

Mock catalogues show prominent baryonic acoustic features and realistic redshift space distortions.

Abstract

Modern redshift surveys are tasked with mapping out the galaxy distribution over enormous distance scales. Existing hydrodynamical simulations, however, do not reach the volumes needed to match upcoming surveys. We present results for the clustering of galaxies using a new, large volume hydrodynamical simulation as part of the MillenniumTNG (MTNG) project. With a computational volume that is $\approx15$ times larger than the next largest such simulation currently available, we show that MTNG is able to accurately reproduce the observed clustering of galaxies as a function of stellar mass. When separated by colour, there are some discrepancies with respect to the observed population, which can be attributed to the quenching of satellite galaxies in our model. We combine MTNG galaxies with those generated using a semi-analytic model to emulate the sample selection of luminous red galaxies (LRGs) and emission line galaxies (ELGs), and show that although the bias of these populations is approximately (but not exactly) constant on scales larger than $\approx10$ Mpc, there is significant scale-dependent bias on smaller scales. The amplitude of this effect varies between the two galaxy types, and also between the semi-analytic model and MTNG. We show that this is related to the distribution of haloes hosting LRGs and ELGs. Using mock SDSS-like catalogues generated on MTNG lightcones, we demonstrate the existence of prominent baryonic acoustic features in the large-scale galaxy clustering. We also demonstrate the presence of realistic redshift space distortions in our mocks, finding excellent agreement with the multipoles of the redshift-space clustering measured in SDSS data.