Explaining the Weak Evolution of the High-Redshift Mass-Metallicity Relation with Galaxy Burst Cycles

Abstract

Recent observations suggest a nearly constant gas-phase mass-metallicity relation (MZR) at $z\gtrsim 5$, in agreement with many theoretical predictions. This lack of evolution contrasts with observations at $z\lesssim 3$, which find an increasing normalization of the MZR with decreasing redshift. We analyze a high-redshift suite of FIRE-2 cosmological zoom-in simulations to identify the physical drivers of the MZR. Previous studies have explained the weak evolution of the high-redshift MZR in terms of weakly evolving or saturated gas fractions, but we find this alone does not explain the evolution in FIRE-2. Instead, stellar feedback following intense bursts of star formation drives enriched gas out of galaxies, resetting their interstellar medium and separating their histories into distinct ``burst cycles". We develop the ``Reduced Burst Model", a simplified gas-regulator model that successfully reproduces the simulated MZR and identifies the dominant drivers of its evolution. As redshift decreases, the metallicity of inflows within burst cycles increases at fixed stellar mass due to increased wind recycling of enriched gas. Meanwhile, the metal mass produced by stars per inflowing gas mass within these cycles decreases because of decreased star formation per gas mass inflowing into the galaxy. The effects of these two processes on the median metallicity largely cancel, holding the MZR constant for $z=5-12$. At fixed stellar mass, the simulations predict lower gas metallicities at higher $\mathrm{H}\alpha$-derived star formation rates, in qualitative agreement with the fundamental metallicity relation (FMR), but this effect is reduced in rest UV-selected samples.

18 pages, 9 figures

References in corpus (51)

• The Origin of the Mass--Metallicity Relation: Insights from 53,000 Star-Forming Galaxies in the SDSS
• Star Formation in the Milky Way and Nearby Galaxies
• Galaxies on FIRE (Feedback In Realistic Environments): Stellar Feedback Explains Cosmologically Inefficient Star Formation
• GIZMO: A New Class of Accurate, Mesh-Free Hydrodynamic Simulation Methods
• FIRE-2 Simulations: Physics versus Numerics in Galaxy Formation
• A fundamental relation between mass, SFR and metallicity in local and high redshift galaxies
• The Mass-Metallicity Relation at z~2
• Gas-regulation of galaxies: the evolution of the cosmic sSFR, the metallicity-mass-SFR relation and the stellar content of haloes
• A New Calculation of the Ionizing Background Spectrum and the Effects of HeII Reionization
• Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE
• Reevaluating Old Stellar Populations
• The Origin of the Galaxy Mass-Metallicity Relation and Implications for Galactic Outflows
• The Origin and Evolution of the Galaxy Mass-Metallicity Relation
• The Cosmic Baryon Cycle and Galaxy Mass Assembly in the FIRE Simulations
• On Extending the Mass-Metallicity Relation of Galaxies by 2.5 Decades in Stellar Mass
• JADES NIRSpec Spectroscopy of GN-z11: Lyman-$\alpha$ emission and possible enhanced nitrogen abundance in a $z=10.60$ luminous galaxy
• Clues to the Origin of the Mass-Metallicity Relation: Dependence on Star Formation Rate and Galaxy Size
• The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z~8
• The MOSDEF Survey: The Evolution of the Mass-Metallicity Relation from $z=0$ to $z\sim 3.3$
• Identification and properties of intense star-forming galaxies at redshifts z>10
• The MOSDEF Survey: Mass, Metallicity, and Star-formation Rate at z~2.3
• The Mass-Metallicity and Luminosity-Metallicity Relation from DEEP2 at z ~ 0.8
• Constraints on star-formation driven galaxy winds from the mass-metallicity relation at z=0
• The evolution of the mass-metallicity relation in IllustrisTNG
• Simulating galaxies in the reionization era with FIRE-2: galaxy scaling relations, stellar mass functions, and luminosity functions
• A fundamental relation between the metallicity, gas content, and stellar mass of local galaxies
• The Chemical Evolution of Star-Forming Galaxies Over the Last 11 Billion Years
• Metal flows of the circumgalactic medium, and the metal budget in galactic halos
• Modelling chemical abundance distributions for dwarf galaxies in the Local Group: the impact of turbulent metal diffusion
• Characterizing mass, momentum, energy and metal outflow rates of multi-phase galactic winds in the FIRE-2 cosmological simulations
• A Model for the Origin of Bursty Star Formation in Galaxies
• The physics of the fundamental metallicity relation
• FIRE-3: Updated Stellar Evolution Models, Yields, & Microphysics and Fitting Functions for Applications in Galaxy Simulations
• Dust attenuation, dust emission, and dust temperature in galaxies at z>=5: a view from the FIRE-2 simulations
• Low Masses and High Redshifts: The Evolution of the Mass-Metallicity Relation
• The equilibrium view on dust and metals in galaxies: Galactic outflows drive low dust-to-metal ratios in dwarf galaxies
• The time-scales probed by star formation rate indicators for realistic, bursty star formation histories from the FIRE simulations
• FIREbox: Simulating galaxies at high dynamic range in a cosmological volume
• A survey of high-$z$ galaxies: SERRA simulations
• The Metallicities of Low Stellar Mass Galaxies and the Scatter in the Mass-Metallicity Relation
• The mass-metallicity and fundamental metallicity relations at z>2 using VLT and Subaru near-infrared spectroscopy of zCOSMOS galaxies
• The mass-metallicity relation at z~1.4 revealed with Subaru/FMOS
• Simulating galaxies in the reionization era with FIRE-2: morphologies and sizes
• First Light And Reionisation Epoch Simulations (FLARES) V: The redshift frontier
• Scaling Laws of Passive-Scalar Diffusion in the Interstellar Medium
• The metallicity evolution of low mass galaxies: New constraints at intermediate redshift
• Stellar Mass--Gas-phase Metallicity Relation at $0.5\le z\le 0.7$: A Power Law with Increasing Scatter toward the Low-mass Regime
• Astraeus V: The emergence and evolution of metallicity scaling relations during the Epoch of Reionization
• Weak Evolution of the Mass-metallicity Relation at Cosmic Dawn in the FirstLight Simulations
• The Extreme Low-mass End of the Mass-Metallicity Relation at $z\sim 7$
• Elevated UV luminosity density at Cosmic Dawn explained by non-evolving, weakly mass-dependent star formation efficiency

Cited by in corpus (1)

• The JWST EXCELS Survey: gas-phase metallicity evolution at 2 < z < 8