Chemical enrichment in cosmological, smoothed particle hydrodynamics simulations

By R. Wiersma, Joop Schaye, Tom Theuns, Claudio Dalla Vecchia, Luca Tornatore. 2009

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We present an implementation of stellar evolution and chemical feedback for smoothed particle hydrodynamics simulations. We consider the timed release of individual elements by both massive (Type II supernovae and stellar winds) and intermediate-mass stars (Type Ia supernovae and asymptotic giant branch stars). We illustrate the results of our method using a suite of cosmological simulations that include new prescriptions for radiative cooling, star formation and galactic winds. Radiative cooling is implemented element-by-element, in the presence of an ionizing radiation background, and we track all 11 elements that contribute significantly to the radiative cooling. While all simulations presented here use a single set of physical parameters, we take specific care to investigate the robustness of the predictions of chemodynamical simulations with respect to the ingredients, the methods and the numerical convergence. A comparison of nucleosynthetic yields taken from the literature indicates that relative abundance ratios may only be reliable at the factor of 2 level, even for a fixed initial mass function. Abundances relative to iron are even more uncertain because the rate of Type Ia supernovae is not well known. We contrast two reasonable definitions of the metallicity of a resolution element and find that while they agree for high metallicities, there are large differences at low metallicities. We argue that the discrepancy is indicative of the lack of metal mixing caused by the fact that metals are stuck to particles. We argue that since this is a (numerical) sampling problem, solving it by using a poorly constrained physical process such as diffusion could have undesired consequences. We demonstrate that the two metallicity definitions result in redshift z= 0 stellar masses that can differ by up to a factor of 2, because of the sensitivity of the cooling rates to the elemental abundances. Finally, we use several 5123 particle simulations to investigate the evolution of the distribution of heavy elements, which we find to be in reasonably good agreement with available observational constraints. We find that by z= 0 most of the metals are locked up in stars. The gaseous metals are distributed over a very wide range of gas densities and temperatures. The shock-heated warm–hot intergalactic medium has a relatively high metallicity of ∼10−1 Z⊙ that evolves only weakly, and is therefore an important reservoir of metals. Any census aiming to account for most of the metal mass will have to take a wide variety of objects and structures into account.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/5f6f800d7d75436ef271eab464437bcbf7fa5f7e

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Citations in the corpus

Bimodality of low-redshift circumgalactic O VI in non-equilibrium EAGLE zoom simulations (2016, methodology): “We evolve all zooms using the equilibrium cooling rates from Wiersma et al. (2009a) to z = 0 using the standard EAGLE code with the only difference being that we do not use kernel-smoothed metallicities to compute cooling rates.”
Introducing the Illustris Project: simulating the coevolution of dark and visible matter in the Universe (2014, methodology): “…& Hernquist 1996; Wiersma, Schaye & Smith 2009a), stellar evolution and chemical enrichment procedures based on stellar synthesis calculations (e.g. Wiersma et al. 2009b; Few et al. 2012), stellar feedback (e.g. Navarro & White 1993; Springel & Hernquist 2003; Stinson et al. 2013), and feedback…”
THE METALLICITY EVOLUTION OF INTERACTING GALAXIES (2011, background): “…is transferred from a single stellar particle to a set of nearest SPH neighbors (e.g. Steinmetz & Mueller 1994; Kawata 2001; Kawata & Gibson 2003; Okamoto et al. 2005; Scannapieco et al. 2005; Stinson et al. 2006; Tornatore et al. 2007; Wiersma et al. 2009; Montuori et al. 2010; Perez et al. 2011).”
A fundamental problem in our understanding of low-mass galaxy evolution (2012, methodology): “…(GIMIC; Crain et al. 2009) simulations use the Gadget-3 SPH and N-body code, with star formation, stellar feedback, radiative cooling and chemodynamics as described in Schaye & Dalla Vecchia (2008), Dalla Vecchia & Schaye (2008), Wiersma, Schaye & Smith (2009a) and Wiersma et al. (2009b).”
The eagle simulations of galaxy formation: Public release of halo and galaxy catalogues (2015, background): “The simulation tracks the time-dependent stellar mass loss due to winds from massive stars and AGB stars, core collapse supernovae and type Ia supernovae (Wiersma et al., 2009b).”
The enrichment of the intergalactic medium with adiabatic feedback – I. Metal cooling and metal diffusion (2009, methodology): “A similar method was also adopted in Wiersma et al. (2009b) for the distribution of metals and the energy from SN Ia.”
Cosmological simulations of the formation of the stellar haloes around disc galaxies (2011, methodology): “The timed release of individual elements by both massive (Type II SNe and stellar winds) and intermediate mass stars (Type Ia SNe and asymptotic giant branch stars) is included following the prescription of Wiersma et al. (2009b).”
Quantifying the effect of baryon physics on weak lensing tomography (2011, background): “The implementation of radiative cooling, star formation, supernovae driven winds, and stellar evolution and mass loss havebeen described in Wiersma, Schaye & Smith (2009), Schaye & Dalla Vecchia (2008), Dalla Vecchia & Schaye (2008), and Wiersma et al. (2009), respectively.”
Physical Models of Galaxy Formation in a Cosmological Framework (2014, background): “Early works employed cooling rates assuming collisional ionization equilibrium (Sutherland & Dopita 1993), but more recent work by Wiersma et al. (2009a) better account for the photo-ionization of metals by the metagalactic radiation field.”
Galaxies on FIRE (Feedback In Realistic Environments): stellar feedback explains cosmologically inefficient star formation (2013, methodology): “We follow 11 separately-tracked species (H, He, C, N, O, Ne, Mg, Si, S, Ca, and Fe, each with its own yield tables associated directly with the different mass return mechanisms below; see Wiersma et al. 2009b).”
TOWARD A COMPLETE ACCOUNTING OF ENERGY AND MOMENTUM FROM STELLAR FEEDBACK IN GALAXY FORMATION SIMULATIONS (2012, background): “C, N, Ne, Mg, Si, Ca and S (see e.g. Wiersma et al. 2009), which we leave for a future investigation.”
Towards a realistic population of simulated galaxy groups and clusters (2013, methodology): “Both were chosen based on empirical constraints but have uncertainties at the factor of 2 level each (Wiersma et al. 2009b).”
The impact of angular momentum on black hole accretion rates in simulations of galaxy formation (2013, methodology): “…an extensive network of subgrid modules to account for the turbulent pressure of the ISM, and implements star formation following the empirical Kennicutt– Schmidt law (Schaye & Dalla Vecchia 2008), chemical enrichment (Wiersma et al. 2009b) and cooling tracking 11 elements (Wiersma et al. 2009a).”
The neutral hydrogen content of galaxies in cosmological hydrodynamic simulations (2013, methodology): “Our version of Gadget-2 includes cooling processes using the primordial abundances as described by Katz et al. (1996), with additional cooling from metal lines assuming photo-ionisation equilibrium from Wiersma et al. (2009).”
The BAHAMAS project: Calibrated hydrodynamical simulations for large-scale structure cosmology (2016, methodology): “Stellar evolution and chemical enrichment are implemented using the model of Wiersma et al. (2009), which computes the timedrelease of 11 elements (H, He, C, N, O, Ne, Mg, Si, S, Ca and 2 http://camb.info/ 3 http://www.mpa-garching.mpg.de/gadget/ 4 https://github.com/sbird/S-GenIC Fe; i.e., all of…”
FIRE-2 simulations: physics versus numerics in galaxy formation (2017, methodology): “With this, high-temperature (> 104 K) metal-line excitation, ionization, and recombination rates then follow Wiersma et al. (2009a).”
The effects of galaxy formation on the matter power spectrum: a challenge for precision cosmology (2011, background): “This implementation of stellar evolution and chemical enrichment is discussed in Wiersma et al. (2009).”
Colours and luminosities of z = 0.1 galaxies in the eagle simulation (2015, methodology): “To account for variations in metal enrichment in the ISM of galaxies, we use the mass-weighted SPH-smoothed metallicity (Wiersma et al. 2009a) calculated for star-forming gas in each EAGLE subhalo, ZSF.”
The dark nemesis of galaxy formation : why hot haloes trigger black hole growth and bring star formation to an end (2016, background): “…(ANARCHY, Schaller et al. (2015)), based on the Gadget code (Springel 2005), and phenomenological subgrid models to capture unresolved physics including cooling, metal enrichment and energy input from stellar feedback and black hole growth (Dalla Vecchia & Schaye 2008; Wiersma et al. 2009b,a).”