Fragmentation inside atomic cooling haloes exposed to Lyman-Werner radiation

Abstract

Supermassive stars born in pristine environments in the early Universe hold the promise of being the seeds for the supermassive black holes observed as high redshift quasars shortly after the epoch of reionisation. H${}_2$ suppression is thought to be crucial in order to negate normal Population III star formation and allow high accretion rates to drive the formation of supermassive stars. Only in the cases where vigorous fragmentation is avoided will a monolithic collapse be successful giving rise to a single massive central object. We investigate the number of fragmentation sites formed in collapsing atomic cooling haloes subject to various levels of background Lyman-Werner flux. The background Lyman-Werner flux manipulates the chemical properties of the gas in the collapsing halo by destroying H${}_2$. We find that only when the collapsing gas cloud shifts from the molecular to the atomic cooling regime is the degree of fragmentation suppressed. In our particular case we find that this occurs above a critical Lyman-Werner background of J $\sim 10$ J${}_{21}$. The important criterion being the transition to the atomic cooling regime rather than the actual value of J, which will vary locally. Once the temperature of the gas exceeds T $\gtrsim$ 10${}^4$ K and the gas transitions to atomic line cooling, then vigorous fragmentation is strongly suppressed.

10 pages (+ 3 appendix). MNRAS accepted

References in corpus (26)

• A luminous quasar at a redshift of z = 7.085
• Formation of Supermassive Black Holes by Direct Collapse in Pregalactic Halos
• Observational constraints on Cosmic Reionization
• An ultra-luminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30
• Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
• Grackle: a Chemistry and Cooling Library for Astrophysics
• Accretion onto the First Stellar Mass Black Holes
• Uncertainties in H2 and HD Chemistry and Cooling and their Role in Early Structure Formation
• Resolving the Formation of Protogalaxies. II. Central Gravitational Collapse
• Star formation at very low metallicity. I: Chemistry and cooling at low densities
• The Evolution of Supermassive Population III Stars
• The critical radiation intensity for direct collapse black hole formation: dependence on the radiation spectral shape
• Accretion onto Intermediate-Mass Black Holes in Dense Protogalactic Clouds
• The formation of compact massive self-gravitating discs in metal-free haloes with virial temperatures of ~ 13000-30000 K
• How realistic UV spectra and X-rays suppress the abundance of direct collapse black holes
• The formation of direct collapse black holes under the influence of streaming velocities
• Is H3+ cooling ever important in primordial gas?
• Star Formation in the First Galaxies I: Collapse Delayed by Lyman-Werner Radiation
• The Direct Collapse of a Massive Black Hole Seed Under the Influence of an Anisotropic Lyman-Werner Source
• Does disk fragmentation prevent the formation of supermassive stars in protogalaxies?
• Radiation hydrodynamics simulations of the formation of direct-collapse supermassive stellar systems
• Vibrational level population of H${}_2$ and H${}_2^{+}$ in the early Universe
• Revised rate coefficients for H${}_2$ and H${}^{-}$ destruction by realistic stellar spectra
• Beyond Jcrit: a critical curve for suppression of H2-cooling in protogalaxies
• The formation of massive primordial stars in the presence of moderate UV backgrounds
• The effect of dark matter resolution on the collapse of baryons in high redshift numerical simulations

Cited by in corpus (3)

• On the Detection of Supermassive Primordial Stars. II. Blue Supergiants
• Growth of Massive Disk and Early Disk Fragmentation in the Primordial Star Formation
• Some First Stars Were Red: Detecting Signatures of Massive Population III Formation Through Long-Term Stochastic Color Variations