Mufasa:The strength and evolution of galaxy conformity in various tracers

Abstract

We investigate galaxy conformity using the Mufasa cosmological hydrodynamical simulation. We show a bimodal distribution in galaxy colour with radius, albeit with too many low-mass quenched satellite galaxies compared to observations. Mufasa produces conformity in observed properties such as colour, sSFR, and HI content; i.e neighbouring galaxies have similar properties. We see analogous trends in other properties such as in environment, stellar age, H${}_2$ content, and metallicity. We introduce quantifying conformity using $S(R)$, measuring the relative difference in upper and lower quartile properties of the neighbours. We show that low-mass and non-quenched haloes have weak conformity ($S(R)\le 0.5$) extending to large projected radii $R$ in all properties, while high-mass and quenched haloes have strong conformity ($S(R)\sim 1$) that diminishes rapidly with $R$ and disappears at $R\ge 1$ Mpc. $S(R)$ is strongest for environment in low-mass haloes, and sSFR (or colour) in high-mass haloes, and is dominated by one-halo conformity with the exception of HI in small haloes. Metallicity shows a curious anti-conformity in massive haloes. Tracking the evolution of conformity for $z=0$ galaxies back in time shows that conformity broadly emerges as a late-time ($z\le 1$) phenomenon. However, for fixed halo mass bins, conformity is fairly constant with redshift out to $z\ge 2$. These trends are consistent with the idea that strong conformity only emerges once haloes grow above Mufasa's quenching mass scale of $\sim 10^{12}{M}_{\odot }$. A quantitative measure of conformity in various properties, along with its evolution, thus represents a new and stringent test of the impact of quenching on environment within current galaxy formation models.

21 pages, 15 figures, accepted for publication in MNRAS (comments are still welcome)

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Cited by in corpus (8)

• Simba: Cosmological Simulations with Black Hole Growth and Feedback
• MIGHTEE-HI: The HI emission project of the MeerKAT MIGHTEE survey
• On the environmental influence of groups and clusters of galaxies beyond the virial radius: Galactic conformity at few Mpc scales
• Star Formation Histories from SEDs and CMDs Agree: Evidence for Synchronized Star Formation in Local Volume Dwarf Galaxies over the Past 3 Gyr
• Unraveling emission line galaxy conformity at z~1 with DESI early data
• The conformity of HI galaxies in ALFALFA-SDSS sample
• Assessing the connection between galactic conformity and assembly-type bias
• Populating Galaxies Into Halos Via Machine Learning on the Simba Simulation