English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Gravitational collapse of a massive primordial gas cloud is thought to be apromising path for the formation of supermassive blackholes in the earlyuniverse. We study conditions for the so-called direct collapse (DC) blackholeformation in a fully cosmological context. We combine a semianalytic model ofearly galaxy formation with halo merger trees constructed from dark matter$N$-body simulations. We locate a total of 68 possible DC sites in a volume of$20\;h^{-1}\;\mathrm{Mpc}$ on a side. We then perform hydrodynamics simulationsfor 42 selected halos to study in detail the evolution of the massive cloudswithin them. We find only two successful cases where the gas clouds rapidlycollapse to form stars. In the other cases, gravitational collapse is preventedby the tidal force exerted by a nearby massive halo, which otherwise shouldserve as a radiation source necessary for DC. Ram pressure stripping disturbsthe cloud approaching the source. In many cases, a DC halo and its nearby lightsource halo merge before the onset of cloud collapse. Only when the DC halo isassembled through major mergers, the gas density increases rapidly to triggergravitational instability. Based on our cosmological simulations, we concludethat the event rate of DC is an order of magnitude smaller than reported inprevious studies, although the absolute rate is still poorly constrained. It isnecessary to follow the dynamical evolution of a DC cloud and its nearbyhalo(s) in order to determine the critical radiation flux for DC.

Cosmological Simulations of Early Blackhole Formation: Halo Mergers, Tidal Disruption, and the Conditions for Direct Collapse