NIHAO III: The constant disc gas mass conspiracy

Abstract

We show that the cool gas masses of galactic discs reach a steady state that lasts many Gyr after their last major merger in cosmological hydrodynamic simulations. The mass of disc gas, M${}_{\mathrm{gas}}$, depends upon a galaxy halo's spin and virial mass, but not upon stellar feedback. Halos with low spin have high star formation efficiency and lower disc gas mass. Similarly, lower stellar feedback leads to more star formation so the gas mass ends up nearly the same irregardless of stellar feedback strength. Even considering spin, the M${}_{\mathrm{gas}}$ relation with halo mass, M${}_{200}$ only shows a factor of 3 scatter. The M${}_{\mathrm{gas}}$--M${}_{200}$ relation show a break at M${}_{200}$=$2\times 10^{11}$ M${}_{\odot }$ that corresponds to an observed break in the M${}_{\mathrm{gas}}$--M${}_{\star }$ relation. The constant disc mass stems from a shared halo gas density profile in all the simulated galaxies. In their outer regions, the profiles are isothermal. Where the profile rises above $n=10^{-3}$ cm${}^{-3}$, the gas readily cools and the profile steepens. Inside the disc, rotation supports gas with a flatter density profile except where supernova explosions disrupt the disc. Energy injection from stellar feedback also provides pressure support to the halo gas to prevent runaway cooling flows. The resulting constant gas mass makes simpler models for galaxy formation possible, either using a "bathtub" model for star formation rates or when modeling chemical evolution.

To be submitted to MNRAS. Comments very welcome in the meantime

References in corpus (20)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• Introducing the Illustris Project: the evolution of galaxy populations across cosmic time
• Star Formation and Feedback in Smoothed Particle Hydrodynamic Simulations--I. Isolated Galaxies
• Concentration, Spin and Shape of Dark Matter Haloes as a Function of the Cosmological Model: WMAP1, WMAP3 and WMAP5 results
• The Role of Pressure in GMC Formation II: The H_2 - Pressure Relation
• The COS-Halos Survey: Physical Conditions and Baryonic Mass in the Low-Redshift Circumgalactic Medium
• The Origin of the Galaxy Mass-Metallicity Relation and Implications for Galactic Outflows
• COLD GASS, an IRAM Legacy Survey of Molecular Gas in Massive Galaxies: II. The non-universality of the Molecular Gas Depletion Timescale
• Modelling discontinuities and Kelvin-Helmholtz instabilities in SPH
• The Initial-Final Mass Relation: Direct Constraints at the Low Mass End
• Accretion of gas onto nearby spiral galaxies
• A Superbubble Feedback Model for Galaxy Simulations
• The Neutral Hydrogen Cosmological Mass Density at z=5
• Why stellar feedback promotes disc formation in simulated galaxies
• A Study in Blue: The Baryon Content of Isolated Low Mass Galaxies
• Evolution of the atomic and molecular gas content of galaxies in dark matter haloes
• How to bend galaxy disc profiles: the role of halo spin
• Galaxy Ecosystems: gas contents, inflows and outflows

Cited by in corpus (28)

• NIHAO project I: Reproducing the inefficiency of galaxy formation across cosmic time with a large sample of cosmological hydrodynamical simulations
• NIHAO IV: Core creation and destruction in dark matter density profiles across cosmic time
• The COS-Halos Survey: Origins of the Highly Ionized Circumgalactic Medium of Star-Forming Galaxies
• The EAGLE simulations: atomic hydrogen associated with galaxies
• The distribution of atomic hydrogen in EAGLE galaxies: morphologies, profiles, and HI holes
• NIHAO IX: the role of gas inflows and outflows in driving the contraction and expansion of cold dark matter haloes
• NIHAO XIV: Reproducing the observed diversity of dwarf galaxy rotation curve shapes in LCDM
• NIHAO project II: Halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations
• NIHAO X: Reconciling the local galaxy velocity function with Cold Dark Matter via mock HI observations
• A model for core formation in dark matter haloes and ultra diffuse galaxies by outflow episodes
• NIHAO V: Too big doesn't fail -- reconciling the conflict between LCDM predictions and the circular velocities of nearby field galaxies
• Phylogeny of the Milky Way's inner disk and bulge populations: Implications for gas accretion, (the lack of) inside-out thick disk formation, and quenching
• NIHAO XIII: Clumpy discs or clumpy light in high redshift galaxies?
• NIHAO XX: The impact of the star formation threshold on the cusp-core transformation of cold dark matter haloes
• NIHAO VI. The hidden discs of simulated galaxies
• NIHAO VIII: Circum-galactic medium and outflows - The puzzles of HI and OVI gas distributions
• The Dekel-Zhao profile: A mass-dependent dark-matter density profile with flexible inner slope and analytic potential, velocity dispersion, and lensing properties
• CHAMP Cosmic Rays
• NIHAO -- XXV. Convergence in the cusp-core transformation of cold dark matter haloes at high star formation thresholds
• NIHAO XVIII: Origin of the MOND phenomenology of galactic rotation curves in a LCDM universe
• An observational test for star formation prescriptions in cosmological hydrodynamical simulations
• CGM properties in VELA and NIHAO simulations; the OVI ionization mechanism: dependence on redshift, halo mass and radius
• HI content in the galactic discs: the role of gravitational instability
• Angular momentum evolution of bulge stars in disc galaxies in NIHAO
• Dynamic equilibrium sets atomic content of galaxies across cosmic time
• Drivers of disc tilting I: Correlations and possible drivers for Milky Way analogues
• Clues to the nature of dark matter from first galaxies
• The stellar orbit distribution in present-day galaxies inferred from the CALIFA survey