Star Formation in the First Galaxies - II: Clustered Star Formation and the Influence of Metal Line Cooling

Abstract

Population III stars are believed to have been more massive than typical stars today and to have formed in relative isolation. The thermodynamic impact of metals is expected to induce a transition leading to clustered, low-mass Population II star formation. In this work, we present results from three cosmological simulations, only differing in gas metallicity, that focus on the impact of metal fine-structure line cooling on the formation of stellar clusters in a high-redshift atomic cooling halo. Introduction of sink particles allows us to follow the process of gas hydrodynamics and accretion onto cluster stars for 4 Myr corresponding to multiple local free-fall times. At metallicities at least $10^{-3}{Z}_{\odot }$, gas is able to reach the CMB temperature floor and fragment pervasively resulting in a stellar cluster of size $\sim 1$ pc and total mass $\sim 1000M_{\odot }$. The masses of individual sink particles vary, but are typically $\sim 100M_{\odot }$, consistent with the Jeans mass when gas cools to the CMB temperature, though some solar mass fragments are also produced. At the low metallicity of $10^{-4}{Z}_{\odot }$, fragmentation is completely suppressed on scales greater than 0.01 pc and total stellar mass is lower by a factor of 3 than in the higher metallicity simulations. The sink particle accretion rates, and thus their masses, are determined by the mass of the gravitationally unstable gas cloud and the prolonged gas accretion over many Myr. The simulations thus exhibit features of both monolithic collapse and competitive accretion. Even considering possible dust induced fragmentation that would occur at higher densities, the formation of a bona fide stellar cluster seems to require metal line cooling and metallicities of at least $10^{-3}{Z}_{\odot }$.

19 pages, 12 figures. Accepted by MNRAS

References in corpus (34)

• Theory of Star Formation
• Cold Dark Clouds: The Initial Conditions for Star Formation
• Cats and Dogs, Hair and A Hero: A Quintet of New Milky Way Companions
• The Statistics of Supersonic Isothermal Turbulence
• The Density Probability Distribution in Compressible Isothermal Turbulence: Solenoidal versus Compressive Forcing
• Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
• Radiation-Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores
• On the Star Formation Efficiency of Turbulent Magnetized Clouds
• Formation of the First Stars
• An extremely primitive halo star
• The Effects of Radiative Transfer on Low-Mass Star Formation
• Fragmentation of star-forming clouds enriched with the first dust
• A new Jeans resolution criterion for (M)HD simulations of self-gravitating gas: Application to magnetic field amplification by gravity-driven turbulence
• Resolving the Formation of Protogalaxies. III. Feedback from the First Stars
• On the Density Distribution in Star-forming Interstellar Clouds
• Can Supermassive Black Holes Form in Metal-Enriched High-Redshift Protogalaxies ?
• Population III stars: hidden or disappeared ?
• The First Galaxies: Assembly, Cooling and the Onset of Turbulence
• Population III star formation in a Lambda CDM universe, I: The effect of formation redshift and environment on protostellar accretion rate
• Probing the Formation of the First Low-Mass Stars with Stellar Archaeology
• Cooling, Gravity and Geometry: Flow-driven Massive Core Formation
• Star formation at very low metallicity. I: Chemistry and cooling at low densities
• Resolving the Formation of Protogalaxies. I. Virialization
• Star Formation in the First Galaxies I: Collapse Delayed by Lyman-Werner Radiation
• The First Galaxies: Assembly of Disks and Prospects for Direct Detection
• The Transition from the First Stars to the Second Stars in the Early Universe
• Conditions for the Formation of First-Star Binaries
• Carbon-Enhanced Metal-Poor Stars, the Cosmic Microwave Background, and the Stellar IMF in the Early Universe
• The Supernova that Destroyed a Protogalaxy: Prompt Chemical Enrichment and Supermassive Black Hole Growth
• Metallicity and the Universality of the IMF
• The impact of thermodynamics on gravitational collapse: filament formation and magnetic field amplification
• Modeling the Pollution of Pristine Gas in the Early Universe
• Mixing of Primordial Gas in Lyman Break Galaxies
• Formation of Compact Clusters from High Resolution Hybrid Cosmological Simulations

Cited by in corpus (57)

• Near-Field Cosmology with Metal-Poor Stars
• The Birth of a Galaxy - III. Propelling reionisation with the faintest galaxies
• Building up the Population III initial mass function from cosmological initial conditions
• The observable signature of late heating of the Universe during cosmic reionization
• Formation of supermassive black hole seeds
• The First Population II Stars Formed in Externally Enriched Mini-halos
• Observational Searches for Galaxies at z > 6
• Transition of the initial mass function in the metal-poor environments
• Decoding the stellar fossils of the dusty Milky Way progenitors
• Recovery from population III supernova explosions and the onset of second generation star formation
• Preserving chemical signatures of primordial star formation in the first low-mass stars
• Does disk fragmentation prevent the formation of supermassive stars in protogalaxies?
• High-resolution spectroscopy of extremely metal-poor stars in the least evolved galaxies: Bootes II
• Two-Dimensional Simulations of Pulsational Pair-Instability Supernovae
• CO/H2, C/CO, OH/CO, and OH/O2 in Dense Interstellar Gas: From High Ionization to Low Metallicity
• Metal Transport and Chemical Heterogeneity in Early Star Forming Systems
• The spectral evolution of the first Galaxies. III. Simulated James Webb Space Telescope spectra of reionization-epoch galaxies with Lyman continuum leakage
• Pair Instability Supernovae of Very Massive Population III Stars
• Impact of the cosmic background radiation on the initial mass function of metal-poor stars
• The Nature of High ${[\mathrm{OIII}]}_{88\mu \mathrm{m}}$/${[\mathrm{CII}]}_{158\mu \mathrm{m}}$ Galaxies in the Epoch of Reionization: Low Carbon Abundance and a Top-Heavy IMF?
• Radiation Hydrodynamical Simulations of the First Quasars
• Impact of dust cooling on direct collapse black hole formation
• A New Statistical Model for Population III Supernova Rates: Discriminating Between $\Lambda$CDM and WDM Cosmologies
• Gravitational collapse and the thermal evolution of low-metallicity gas clouds in the early Universe
• Exploring the nature of the Lyman-$\alpha$ emitter CR7
• Accretion Phase of Star Formation in Clouds with Different Metallicities
• A chemical model for the interstellar medium in galaxies
• Dust grain growth and the formation of the extremely primitive star SDSS J102915+172927
• Formation of the First Low-Mass Stars from Cosmological Initial Conditions
• Star formation in the first galaxies - III. Formation, evolution, and characteristics of the first stellar cluster
• The First Gamma-Ray Bursts in the Universe
• Low-metallicity star formation: Relative impact of metals and magnetic fields
• Abundance anomalies in metal-poor stars from Population III supernova ejecta hydrodynamics
• How the First Stars Regulated Star Formation. II. Enrichment by Nearby Supernovae
• Thermal instability and multi-phase interstellar medium in the first galaxies
• Population III Hypernovae
• Finding the First Cosmic Explosions. IV. 90 - 140 M${}_{\odot }$ Pair-Instability Supernovae
• Formation of carbon-enhanced metal-poor stars in the presence of far ultraviolet radiation
• First star formation in ultra-light particle dark matter cosmology
• Population III star formation in an X-ray background: III. Periodic radiative feedback and luminosity induced by elliptical orbits
• Toward $abinitio$ extremely metal poor stars
• Detecting strongly lensed supernovae at z ~ 5-7 with LSST
• Effects of turbulence and rotation on protostar formation as a precursor to seed black holes
• SIEGE III: The formation of dense stellar clusters in sub-parsec resolution cosmological simulations with individual star feedback
• Lyman-$\alpha$ feedback prevails at Cosmic Dawn: Implications for the first galaxies, stars, and star clusters
• Physics of Superluminous Supernovae
• Gravitational Fragmentation of Extremely Metal-poor Circumstellar Discs
• Detecting Ancient Supernovae at z ~ 5 - 12 with CLASH
• Metallicity Dependence of Molecular Cloud Hierarchical Structure at Early Evolutionary Stages
• Do fragmentation and accretion affect the stellar Initial Mass Function?
• The Luminosity of Population III Star Clusters
• Contribution of the first galaxies to the cosmic far-infrared/sub-millimeter background - I. Mean background level
• The chemical evolution of self-gravitating primordial disks
• Redshift Horizon for Detecting the First Galaxies in Far-Infared Surveys
• Condition for low-mass star formation in shock-compressed metal-poor clouds
• Star Formation for Predictive Primordial Galaxy Formation
• Population III Star Formation in an X-ray background: I. Critical Halo Mass of Formation and Total Mass in Stars