A model for cosmological simulations of galaxy formation physics

Abstract

We present a new comprehensive model of the physics of galaxy formation designed for large-scale hydrodynamical simulations of structure formation using the moving mesh code AREPO. Our model includes primordial and metal line cooling with self-shielding corrections, stellar evolution and feedback processes, gas recycling, chemical enrichment, a novel subgrid model for the metal loading of outflows, black hole (BH) seeding, BH growth and merging procedures, quasar-and radio-mode feedback, and a prescription for radiative electromagnetic (EM) feedback from active galactic nuclei (AGN). Our stellar evolution and chemical enrichment scheme follows nine elements (H, He, C, N, O, Ne, Mg, Si, Fe) independently. Stellar feedback is realised through kinetic outflows. The metal mass loading of outflows can be adjusted independently of the wind mass loading. This is required to simultaneously reproduce the stellar mass content of low mass haloes and their gas oxygen abundances. Radiative EM AGN feedback is implemented assuming an average spectral energy distribution and a luminosity-dependent scaling of obscuration effects. This form of feedback suppresses star formation more efficiently than continuous thermal quasar-mode feedback alone, but is less efficient than mechanical radio-mode feedback in regulating star formation in massive haloes. We contrast simulation predictions for different variants of our galaxy formation model with key observations, allowing us to constrain the importance of different modes of feedback and their uncertain efficiency parameters. We identify a fiducial best match model and show that it reproduces, among other things, the cosmic star formation history, the stellar mass function, the stellar mass -halo mass relation, g-, r-, i-, z-band SDSS galaxy luminosity functions, and the Tully-Fisher relation. We can achieve this success only if we invoke very strong forms of stellar and AGN feedback such that star formation is adequately reduced in both low and high mass systems. In particular, the strength of radio-mode feedback needs to be increased significantly compared to previous studies to suppress efficient cooling in massive, metal-enriched haloes.

The size evolution of star-forming and quenched galaxies in the IllustrisTNG simulation

“…In addition, we calculate two-dimensional half-light radii in the r-band, Rr,2D, by projecting the simulation box along a random direction with respect to the orientation of each individual galaxy 4 . The rband stellar luminosities are calculated as in Vogelsberger et al (2013).…”

The impact of galactic properties and environment on the quenching of central and satellite galaxies: a comparison between SDSS, Illustris and L-Galaxies

“…The formation of the stellar bulge and black hole are modelled quite independently in the Illustris simulation and hence relations between these two components may be taken as predictions rather than necessary consequences of the implementation, unlike in many semi-analytic models. Full details on the prescriptions for black hole growth in Illustris are given in Vogelsberger et al (2013Vogelsberger et al ( , 2014a. As with L-Galaxies, the radio mode AGN feedback prescription in Illustris leads to a quenching probability which is primarily a function of black hole mass, i.e.…”

The role of mergers and halo spin in shaping galaxy morphology

“…The main simulation considered in this study, known simply as the Illustris simulation, evolves 1820 3 DM particles with a mass of 6.26 × 10 6 M , along with approximately 1820 3 baryonic resolution elements (stellar particles or gas cells) with an average mass of 1.26 × 10 6 M . The simulation features a physical model of galaxy formation (Vogelsberger et al 2013;Torrey et al 2014) which has been shown to reproduce various galaxy observables, including several which were not used in the calibration of the model (e.g. Sales et al 2015;Wellons et al 2015;Rodriguez-Gomez et al 2015;Genel et al 2015;Mistani et al 2016;Cook et al 2016).…”