Moving mesh cosmology: the hydrodynamics of galaxy formation

By D. Sijacki, M. Vogelsberger, D. Keres̆, Volker Springel, L. Hernquist. 2011

145 citations recorded by the source corpus.

We present a detailed comparison between the well-known smoothed particle hydrodynamics (SPH) code gadget and the new moving-mesh code arepo on a number of hydrodynamical test problems. Through a variety of numerical experiments with increasing complexity we establish a clear link between simple test problems with known analytic solutions and systematic numerical effects seen in cosmological simulations of galaxy formation. Our tests demonstrate deficiencies of the SPH method in several sectors. These accuracy problems not only manifest themselves in idealized hydrodynamical tests, but also propagate to more realistic simulation set-ups of galaxy formation, ultimately affecting local and global gas properties in the full cosmological framework, as highlighted in companion papers by Vogelsberger et al. and Keres et al. We find that an inadequate treatment of fluid instabilities in gadget suppresses entropy generation by mixing, underestimates vorticity generation in curved shocks and prevents efficient gas stripping from infalling substructures. Moreover, in idealized tests of inside-out disc formation, the convergence rate of gas disc sizes is much slower in gadget due to spurious angular momentum transport. In simulations where we follow the interaction between a forming central disc and orbiting substructures in a massive halo, the final disc morphology is strikingly different in the two codes. In arepo, gas from infalling substructures is readily depleted and incorporated into the host halo atmosphere, facilitating the formation of an extended central disc. Conversely, gaseous sub-clumps are more coherent in gadget simulations, morphologically transforming the central disc as they impact it. The numerical artefacts of the SPH solver are particularly severe for poorly resolved flows, and thus inevitably affect cosmological simulations due to their inherently hierarchical nature. Taken together, our numerical experiments clearly demonstrate that arepo delivers a physically more reliable solution.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/6c81df690b912e56e1c406cfc1b09824031536f5

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Citations in the corpus

Gasoline2: a modern smoothed particle hydrodynamics code (2017, background): “…codes generally agree well in simulations that involve supersonic flow (e.g. comparison projects by Kitsionas et al. 2009; Price & Federrath 2010; Bauer & Springel 2012), highMach number shocks (Tasker et al. 2008; Sijacki et al. 2012) and gravitational structure formation (O’Shea et al. 2005).”
Galaxy morphology and star formation in the Illustris Simulation at z = 0 (2015, methodology): “Using the Arepo code for gravity and gas dynamics (Springel 2010), these simulations evolve simultaneously the gas, stars, and dark matter components from cosmological initial conditions (Vogelsberger et al. 2012; Kereš et al. 2012; Sijacki et al. 2012).”
The EAGLE simulations of galaxy formation: the importance of the hydrodynamics scheme (2015, background): “G A ] 1 6 rectly relevant the accretion of gas and satellite of galaxies (Frenk et al. 1999; Marri & White 2003; Okamoto et al. 2003; O’Shea et al. 2005; Agertz et al. 2007; Wadsley et al. 2008; Mitchell et al. 2009; Kereš et al. 2012; Sijacki et al. 2012).”
FIRE-2 simulations: physics versus numerics in galaxy formation (2017, background): “…accurately, add noise, and artificially suppress phenomena such as fluid mixing and sub-sonic turbulence (Agertz et al. 2007; Bauer & Springel 2012; Sijacki et al. 2012), potentially leading directly to large differences in cooling in massive galaxies (Kereš et al. 2012; Torrey et al. 2012).”
Moving mesh cosmology: tracing cosmological gas accretion (2013, background): “AREPO galaxies are more disk-like and more rotationally supported, with systematically larger disk scale lengths (Torrey et al. 2011) in part because they are significantly built from the diffuse, hot halo gas, which has a large reservoir of angular momentum (see also Sijacki et al. 2012).”
CO-dark gas and molecular filaments in Milky Way-type galaxies (2014, methodology): “In addition, AREPO has been shown to perform much better than standard SPH for modelling highly multiphase flows (Sijacki et al. 2012) and subsonic turbulence (Bauer & Springel 2012).”
Stellar and Quasar Feedback in Concert: Effects on AGN Accretion, Obscuration, and Outflows (2015, background): “Together these variations produce the range of numerical effects which span the major SPH-grid code differences often discussed in the literature (see references above and Price & Federrath 2010; Bauer & Springel 2012; Sijacki et al. 2012).”
The Illustris simulation: the evolving population of black holes across cosmic time (2014, background): “…tested and validated on a number of computational problems and small scale cosmological simulations (Springel 2010, 2011; Bauer & Springel 2012; Sijacki et al. 2012; Vogelsberger et al. 2012; Kereš et al. 2012; Torrey et al. 2012; Genel et al. 2013; Nelson et al. 2013) demonstrating excellent…”
The formation of disc galaxies in high-resolution moving-mesh cosmological simulations (2013, methodology): “…at the level of the ordinary hydrodynamical equations that describe an ideal gas, simulation results can be strongly affected by the numerical scheme employed for solving hydrodynamics, as emphasized recently (Vogelsberger et al. 2012; Sijacki et al. 2012; Kereš et al. 2012; Torrey et al. 2012).”
Introducing the Illustris Project: the evolution of galaxy populations across cosmic time (2014, methodology): “…shown this method to be advantageous in terms of accuracy compared to the traditional methods of smoothed particle hydrodynamics (SPH) and adaptive mesh refinement (AMR; Kereš et al. 2012; Sijacki et al. 2012; Torrey et al. 2012; Vogelsberger et al. 2012; Genel et al. 2013; Nelson et al. 2013).”
THE COS-HALOS SURVEY: RATIONALE, DESIGN, AND A CENSUS OF CIRCUMGALACTIC NEUTRAL HYDROGEN (2013, background): “Recent simulations based on new treatments of hydrodynamics have questioned the details of cold accretion predictions (Sijacki et al. 2012; Bird et al. 2013), but in any case it is important that observations provide tests of any proposed accretion scenarios.”
Galaxies on FIRE (Feedback In Realistic Environments): stellar feedback explains cosmologically inefficient star formation (2013, methodology): “…of hot halos in massive galaxies, they are generally unimportant inside cold star-forming gas, or in sub-L∗ halos, where the flows of interest tend to be highly supersonic and gravity-dominated (see e.g. Kitsionas et al. 2009; Price & Federrath 2010; Bauer & Springel 2012; Sijacki et al. 2012).”
Improving the convergence properties of the moving-mesh code AREPO (2015, methodology): “These new methods have matured into interesting alternative codes that have already been widely applied in cosmological simulations of structure formation (e.g. Vogelsberger et al. 2012; Sijacki et al. 2012; Marinacci et al. 2013; Vogelsberger et al. c© 0000 RAS ar X iv :1 50 3.”
THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z ≲ 1 (2013, methodology): “…physics and modified methods to solve the hydrodynamical equations have become possible with improved computational power (e.g., Springel & Hernquist 2003; Kobayashi 2004; Oppenheimer et al. 2010; Springel 2010; Smith et al. 2011; Kereš et al. 2012; Sijacki et al. 2012; Vogelsberger et al. 2012).”
Submillimetre galaxies in a hierarchical universe: number counts, redshift distribution, and implications for the IMF (2012, background): “Beyond the core 5 Recently, some authors (Agertz et al. 2007; Springel 2010b; Bauer & Springel 2012; Sijacki et al. 2012) have noted several significant flaws inherent in the traditional formulation of SPH, including the artificial suppression of fluid instabilities, artificial damping of turbulent…”
Simulating galaxy formation with black hole driven thermal and kinetic feedback (2016, methodology): “We thus also aim to take recent improvements in the accuracy of the hydrodynamical modelling into account (Bauer & Springel 2012; Kereš et al. 2012; Sijacki et al. 2012; Vogelsberger et al. 2012; Pakmor et al. 2016).”
Theoretical Challenges in Galaxy Formation (2016, methodology): “…moving mesh code AREPO (Springel 2010a) similarly suffers from numerical diffusion but combines advantages of the Lagrangian and Eulerian approaches and performs much better than traditional SPH codes like GADGET on mixing problems with a high convergence rate (Sijacki et al. 2012, Springel 2010b).”
The star formation main sequence and stellar mass assembly of galaxies in the Illustris simulation (2014, methodology): “…gas inflow rates are less applicable to the Illustris simulation than to semi-analytical models because in Illustris gas accretion is explicitly treated using an accurate hydrodynamics algorithm (e.g. Sijacki et al. 2012; Vogelsberger et al. 2012; Kereš et al. 2012; Bauer & Springel 2012).”
A new class of accurate, mesh-free hydrodynamic simulation methods (2014, background): “…over-damp the behavior of sub-sonic (pressure-dominated) turbulence and waves (Kitsionas et al. 2009; Price & Federrath 2010; Bauer & Springel 2012; Sijacki et al. 2012), produce orders-of-magnitude higher numerical viscosity in flows which should be inviscid (leading to artificial angular…”
AGN-driven quenching of star formation: morphological and dynamical implications for early-type galaxies (2013, background): “It can have critical consequences on the amount of gas mixing between satellites (cold phase) and the hot ambient medium in massive haloes which can lead to more efficient gas cooling (Sijacki et al. 2012).”