Not massive enough to continue the fusion reaction, beyond oxygen, they become a white dwarf and cool down.īut for stars with about 5 times the mass of our Sun, the fusion process continues further up the periodic table to silicon, aluminum, potassium, and so on, all the way to iron. Stars with the mass of our Sun pretty much stop there. Since the star continues to pump out radiation, it balances out the gravitational forces trying to compress it. After it runs out of helium, it switches to carbon, and then oxygen. This fusion process is an exothermic reaction, meaning it releases more energy than it requires.Īs the star consumes the last of its hydrogen, it switches to the stockpiles of helium that it has built up. Image credit: NASA/JPL-CaltechAt the core, millions of tonnes of hydrogen are being converted into helium every second, releasing gamma radiation. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. In most previous studies, those efficient BH assembly processes are considered to take place in atomically-cooling dark-matter (DM) halos with virial temperature of T vir 10 4 K, (corresponding to DM halo masses of M h 10 7 M at z ∼ 10−15), where typical first-galaxies would form (Bromm & Yoshida 2011).This artist’s concept illustrates a supermassive black hole with millions to billions times the mass of our sun. 2021) and runaway stellar mergers in dense regions (Devecchi & Volonteri 2009 Sakurai et al. 2021) and the formation of massive heavy seed BHs through primordial star formation (Omukai 2001 Bromm & Loeb 2003 Lodato & Natarajan 2006 Shang et al. All black holes are formed from the gravitational collapse of a star, usually having a great, massive, core. 2020) for instance rapid gas collapse into the nuclei of early protogalaxies (Volonteri & Rees 2005 Inayoshi et al. The existence of those high-redshift quasars requires their quick assembly mechanisms (Volonteri 2012 Haiman 2013 Inayoshi et al. This affords a window for future observations with JWST and sensitive X-ray telescopes to diagnose the direct-collapse scenario, by detecting similar OMBGs and establishing their uniquely high black hole-to-stellar mass ratio. We thus consider here a more general case of a dense massive protostar cluster at low metallicity (<~ 10^$, neighboring haloes until their mergers are complete at $z\approx 8$. Numerical simulations have shown that the conditions for the classical direct collapse scenario are very restrictive and fragmentation is very difficult to be avoided. While large numbers of supermassive black holes have been detected at z>6, their origin is still essentially unclear. The direct collapse model thus provides a viable pathway of forming high-mass black holes The central object reaches ∼1000 M⊙ within four free-fall times, and we expect further growth up to 106 M⊙ through accretion in about 1 Myr. Resulting from turbulent accretion and occasional mergers. Our findings show that while fragmentation occasionally occurs, it does not prevent the growth of a central massive object The peak density reached in these simulations is 1.2 Of the first peak, and study the impact of subgrid-scale turbulence. Large eddy simulations to date which track the evolution of high-density regions on scales of 0.25 au beyond the formation We present here the highest resolution cosmological Plays a central role in regulating accretion and transporting angular momentum. Gravitational collapse in atomic cooling haloes with virial temperatures Tvir ≥ 104 K may lead to the formation of massive seed black holes in the presence of an intense background ultraviolet flux. Direct collapse has emerged as a highly plausible scenario to formīlack holes as it provides seed masses of 105–106 M⊙. Different pathways have been suggested to assemble supermassiveīlack holes in the first billion years after the big bang. Their formation at such early epochs is still an enigma.
Supermassive black holes with up to a 109 M⊙ dwell in the centres of present-day galaxies, and their presence has been confirmed at z ≥ 6.
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