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    Fragmentation inside atomic cooling haloes exposed to Lyman-Werner radiation

    Regan, John and Downes, Turlough P. (2018) Fragmentation inside atomic cooling haloes exposed to Lyman-Werner radiation. Monthly Notices of the Royal Astronomical Society, 475 (4). pp. 4636-4647. ISSN 1365-2966

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    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. H2 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 H2. 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 ∼ 10 J21. 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 & 104 K and the gas transitions to atomic line cooling, then vigorous fragmentation is strongly suppressed.

    Item Type: Article
    Keywords: Cosmology; theory; large-scale structure; first stars; methods; numerical;
    Academic Unit: Faculty of Science and Engineering > Theoretical Physics
    Faculty of Science and Engineering > Research Institutes > Hamilton Institute
    Item ID: 13183
    Depositing User: John Regan
    Date Deposited: 07 Aug 2020 20:25
    Journal or Publication Title: Monthly Notices of the Royal Astronomical Society
    Publisher: The Royal Astronomical Society
    Refereed: Yes

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