Cosmological smoothed particle hydrodynamics simulations: a hybrid multiphase model for star formation

By Volker Springel, Lars Hernquist Mpa, Harvard-CfA. 2002

1,662 citations recorded by the source corpus.

We present a model for star formation and supernova feedback that describes the multiphase structure of star-forming gas on scales that are typically not resolved in cosmological simulations. Our approach includes radiative heating and cooling, the growth of cold clouds embedded in an ambient hot medium, star formation in these clouds, feedback from supernovae in the form of thermal heating and cloud evaporation, galactic winds and outflows, and metal enrichment. Implemented using smoothed particle hydrodynamics, our scheme is a significantly modified and extended version of the grid-based method of Yepes et al., and enables us to achieve a high dynamic range in simulations of structure formation. We discuss properties of the feedback model in detail and show that it predicts a self-regulated, quiescent mode of star formation, which, in particular, stabilizes the star-forming gaseous layers of disc galaxies. The parametrization of this mode can be reduced to a single free quantity that determines the overall time-scale for star formation. We fix this parameter numerically to match the observed rates of star formation in local disc galaxies. When normalized in this manner, cosmological simulations employing our model nevertheless overproduce the observed cosmic abundance of stellar material. We are thus motivated to extend our feedback model to include galactic winds associated with star formation. Using small-scale simulations of individual star-forming disc galaxies, we show that these winds produce either galactic fountains or outflows, depending on the depth of the gravitational potential. In low-mass haloes, winds can greatly suppress the overall efficiency of star formation. When incorporated into cosmological simulations, our combined model for star formation and winds predicts a cosmic star formation density that is consistent with observations, provided that the winds are sufficiently energetic. Moreover, outflows from galaxies in these simulations drive chemical enrichment of the intergalactic medium – in principle, accounting for the presence of metals in the Lyman α forest.

Subfields: Astronomy and Astrophysics, Computational Mechanics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/89b6b18dc27a213b477557c60777e5f65a11053a

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Citations in the corpus

THE BIRTH OF A GALAXY: PRIMORDIAL METAL ENRICHMENT AND STELLAR POPULATIONS (2010, methodology): “This treatment of cold gas accretion is similar to a star formation model with a multi-phase subgrid model (Springel & Hernquist 2003) but is employed in a simulation that can resolve the multi-phase interstellar stellar medium (ISM).”
The optical morphologies of galaxies in the IllustrisTNG simulation: a comparison to Pan-STARRS observations (2018, background): “MNRAS 000, 000–000 (0000) cells above a given density threshold (nH ∼ 0.1 cm−3), which are stochastically converted into stellar particles (for details, see Springel & Hernquist 2003; Vogelsberger et al. 2013; Pillepich et al. 2018a).”
The star formation activity of IllustrisTNG galaxies: main sequence, UVJ diagram, quenched fractions, and systematics (2018, methodology): “In the TNG model, the star formation is treated following Springel & Hernquist (2003): the gas is stochastically converted into star particles once its density exceeds nH = 0.1 cm−3 and on a time scale determined so that it empirically reproduces the KennicuttSchmidt relation (Kennicutt 1989).”
Self-regulated star formation in galaxies via momentum input from massive stars (2011, methodology): “…the net stellar mass formed from cooled baryons exceeds that observed by an order of magnitude or more, particularly in lower mass haloes (e.g. Katz, Weinberg & Hernquist 1996; Somerville & Primack 1999; Cole et al. 2000; Springel & Hernquist 2003b; Kereš et al. 2009, and references therein).”
Where Are the Baryons? II. Feedback Effects (2005, background): “…progress has been made recently to provide a better treatment of the multiphase interstellar medium (Yepes et al. 1997; Elizondo et al. 1999a, 1999b; Hultman & Pharasyn 1999; Ritchie & Thomas 2001; Springel & Hernquist 2003), but the generation of GSWs is far from being adequately modeled.”
THE METALLICITY EVOLUTION OF INTERACTING GALAXIES (2011, methodology): “In addition to accounting for gravity and hydrodynamics, our simulations also include a sub-grid two-phase model of star formation, supernova feedback, radiative cooling of gas, and star formation driven winds (Katz et al. 1996; Springel & Hernquist 2003, hereafter SH03).”
Implementation of feedback in smoothed particle hydrodynamics: towards concordance of methods (2012, background): “…kinetic feedback approach, in which all or part of the energy is given to the surrounding medium as momentum (e.g. Navarro & White 1993; Mihos & Hernquist 1994; Kawata 2001; Kay et al. 2002; Springel & Hernquist 2003; Oppenheimer & Davé 2006; Dalla Vecchia & Schaye 2008; Dubois & Teyssier 2008).”
The star formation main sequence and stellar mass assembly of galaxies in the Illustris simulation (2014, background): “Instead a sub-resolution model is implemented (Springel & Hernquist 2003; Vogelsberger et al. 2013, 2014a), where unresolved physical processes such as the formation of molecular clouds, thermal instabilities, and supernova feedback are coarsely described with an effective equation of state.”
The UV continua and inferred stellar populations of galaxies at z ~7-9 revealed by the Hubble Ultra-Deep Field 2012 campaign (2012, background): “…(Yoshida et al. 2003; Maio et al. 2007, 2009), PopIII and PopII/I star formation according to the corresponding initial mass function (IMF; Tornatore, Ferrara & Schneider 2007), gas cooling from resonant and fine-structure lines (Maio et al. 2007) and feedback effects (Springel & Hernquist 2003).”
Black Holes in Galaxy Mergers: Evolution of Quasars (2005, methodology): “…Springel et al. (2005b) have developed a methodology for incorporating black hole growth and feedback into hydrodynamical simulations of galaxy mergers that includes a multiphase model for star formation and pressurization of the interstellar gas by supernova feedback (Springel & Hernquist 2003).”
First results from the TNG50 simulation: galactic outflows driven by supernovae and black hole feedback (2019, methodology): “No model for galaxy formation currently succeeds without incorporating both mechanisms (Springel & Hernquist 2003; Croton et al. 2006).”
First results from the IllustrisTNG simulations: the stellar mass content of groups and clusters of galaxies (2017, neutral): “…follows radiative gas cooling modulated by a time-variable UV background, star formation regulated by a subgrid model for the interstellar medium (Springel & Hernquist 2003), galactic wind feedback powered by supernova explosions, a detailed metal enrichment model that tracks 9 elements and uses…”
Substructures in hydrodynamical cluster simulations (2008, methodology): “As a phenomenological extension of this feedback scheme, Springel & Hernquist (2003) also included a simple model for galactic winds, whose velocity,vw, scales with the fractionη of the SN type-II feedback energy that contributes to the winds.”
The MassiveBlack-II simulation: The evolution of haloes and galaxies to z ~ 0 (2014, methodology): “These are hydrodynamics (using SPH), cooling, a subgrid multiphase model for star formation (Springel & Hernquist 2003a) and subgrid BH modelling (Di Matteo, Springel & Hernquist 2005; Springel, Di Matteo & Hernquist 2005a), both with feedback.”
A fundamental problem in our understanding of low-mass galaxy evolution (2012, methodology): “Examples include the smoothed particle hydrodynamics (SPH) simulations by Springel & Hernquist (2003) and Crain et al. (2009).”
The Lyman alpha forest opacity and the metagalactic hydrogen ionization rate at z~ 2-4 (2004, methodology): “Comparisons with identical simulations using the multi-phase model of Springel & Hernquist (2003) show little difference in the Lyα absorption (Viel, Haehnelt & Springel 2004).”
Vertical disc heating in Milky Way-sized galaxies in a cosmological context (2015, positive): “The interstellar medium gas is modelled with an effective equation of state (Springel & Hernquist 2003), in which star formation occurs stochastically provided the density of a gas cell is high enough, and the temperature is not higher than that inferred by the equation of state.”