{
  "id": "1702.06148",
  "version": "v1",
  "published": "2017-02-20T19:17:16.000Z",
  "updated": "2017-02-20T19:17:16.000Z",
  "title": "FIRE-2 Simulations: Physics versus Numerics in Galaxy Formation",
  "authors": [
    "Philip F Hopkins",
    "Andrew Wetzel",
    "Dusan Keres",
    "Claude-Andre Faucher-Giguere",
    "Eliot Quataert",
    "Michael Boylan-Kolchin",
    "Norman Murray",
    "Christopher C. Hayward",
    "Shea Garrison-Kimmel",
    "Cameron Hummels",
    "Robert Feldmann",
    "Paul Torrey",
    "Xiangcheng Ma",
    "Daniel Angles-Alcazar",
    "Kung-Yi Su",
    "Matthew Orr",
    "Denise Schmitz",
    "Ivanna Escala",
    "Robyn Sanderson",
    "Michael Y. Grudic",
    "Zachary Hafen",
    "Ji-Hoon Kim",
    "Alex Fitts",
    "James S. Bullock",
    "Coral Wheeler",
    "T. K. Chan",
    "Oliver D. Elbert",
    "Desika Narananan"
  ],
  "comment": "66 pages, 39 figures. Simulation animations and visualizations available at http://www.tapir.caltech.edu/~phopkins/Site/animations and http://fire.northwestern.edu Paper includes complete FIRE algorithms and public ICs (http://www.tapir.caltech.edu/~phopkins/publicICs)",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO",
    "astro-ph.IM"
  ],
  "abstract": "The Feedback In Realistic Environments (FIRE) project explores the role of feedback in cosmological simulations of galaxy formation. Previous FIRE simulations used an identical source code (FIRE-1) for consistency. Now, motivated by the development of more accurate numerics (hydrodynamic solvers, gravitational softening, supernova coupling) and the exploration of new physics (e.g. magnetic fields), we introduce FIRE-2, an updated numerical implementation of FIRE physics for the GIZMO code. We run a suite of simulations and show FIRE-2 improvements do not qualitatively change galaxy-scale properties relative to FIRE-1. We then pursue an extensive study of numerics versus physics in galaxy simulations. Details of the star-formation (SF) algorithm, cooling physics, and chemistry have weak effects, provided that we include metal-line cooling and SF occurs at higher-than-mean densities. We present several new resolution criteria for high-resolution galaxy simulations. Most galaxy-scale properties are remarkably robust to the numerics that we test, provided that: (1) Toomre masses (cold disk scale heights) are resolved; (2) feedback coupling ensures conservation and isotropy, and (3) individual supernovae are time-resolved. As resolution increases, stellar masses and profiles converge first, followed by metal abundances and visual morphologies, then properties of winds and the circumgalactic medium. The central (~kpc) mass concentration of massive (L*) galaxies is sensitive to numerics, particularly how winds ejected into hot halos are trapped, mixed, and recycled into the galaxy. Multiple feedback mechanisms are required to reproduce observations: SNe regulate stellar masses; OB/AGB mass loss fuels late-time SF; radiative feedback suppresses instantaneous SFRs and accretion onto dwarfs. We provide tables, initial conditions, and the numerical algorithms required to reproduce our simulations.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-02-20T19:17:16.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "simulations",
      "galaxy formation",
      "feedback suppresses instantaneous sfrs",
      "change galaxy-scale properties relative",
      "mass loss fuels late-time sf"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 66,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}