On the influence of halo mass accretion history on galaxy properties and assembly bias

Abstract

Halo assembly bias is the secondary dependence of the clustering of dark-matter haloes on their assembly histories at fixed halo mass. This established dependence is expected to manifest itself on the clustering of the galaxy population, a potential effect commonly known as galaxy assembly bias. Using the IllustrisTNG300 magnetohydrodynamical simulation, we analyse the dependence of the properties and clustering of galaxies on the shape of the specific mass accretion history of their hosting haloes (sMAH). We first show that several halo and galaxy properties strongly correlate with the slope of the sMAH (𝛽) at fixed halo mass. Namely, haloes with increasingly steeper 𝛽 increment their halo masses faster at early times, and their hosted galaxies present larger stellar-to-halo mass ratios, lose their gas faster, reach the peak of their star formation histories at higher redshift, and become quenched earlier. We also demonstrate that 𝛽 is more directly connected to these key galaxy formation properties than other broadly employed halo proxies, such as formation time. Finally, we measure the secondary dependence of galaxy clustering on 𝛽 at fixed halo mass as a function of redshift. By tracing back the evolution of individual haloes, we show that the amplitude of the galaxy assembly bias signal for the progenitors of 𝑧 = 0 galaxies increases with redshift, reaching a factor of 2 at 𝑧 = 1 for haloes of 𝑀 halo = 10 11.5 − 10 12 ℎ −1 M . The measurement of the evolution of assembly bias along the merger tree provides a new theoretical perspective to the study of secondary bias. Our findings, which show a tight relationship between halo accretion and both the clustering and some of the main observational properties of the galaxy population, have also important implications for the generation of mock catalogues for upcoming cosmological surveys.

Do gas-poor galaxy clusters have different galaxy populations? The positive covariance of hot and cold baryons

“…We plan to improve our concentration measurement in a forthcoming paper considering a wider galaxy population inclusive of less massive galaxies and to investigate the subject using the Magneticum simulation (Dolag et al 2016). An other promising way to give insight to the outlined scenario is that of Montero-Dorta et al (2021), who point out the relevant role of the mass accretion history in delineating the cluster properties, using the Illustris-TNG300 magnetohydrodynamical simulations.…”

SDSS-IV MaNGA: How the stellar populations of passive central galaxies depend on stellar and halo mass

“…At fixed M h , central galaxies that are dispersion dominated, redder, larger, and have higher M * are more strongly clustered, especially for M h < 10 13 h −1 M (Montero-Dorta et al 2020). In addition, centrals in IllustrisTNG with high M * -to-M h ratios exhausted their gas reservoirs earlier, thus quenching at higher redshifts (Montero-Dorta et al 2021).…”

Machine learning synthetic spectra for probabilistic redshift estimation: SYTH-Z

“…It is natural to use 𝑀 peak because galaxies hosted by more massive haloes present larger masses, reach the peak of their SFH at higher redshift, and become quenched at earlier times (e.g., Chaves-Montero & Hearin 2020). We use 𝛽 MAH because this parameter captures the dependence of galaxy properties on the assembly history of its host halo; for example, at fixed halo mass, the galaxies with a steeper slope reach the peak of their SFH at higher redshift and become quenched at earlier times (Montero-Dorta et al 2021).…”