How does a star turn into a black hole
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How a Star Turns into a Black Hole
Stellar Evolution and Core Collapse
The transformation of a star into a black hole is a complex process that typically begins with the star's core collapse. For very massive stars, particularly those with masses exceeding 70 solar masses, the core collapse is driven by gravitational forces that overpower the internal pressure supporting the star. This collapse leads to the formation of a proto-neutron star (PNS)2. In some cases, the intense neutrino heating and violent convection behind the shock can revive the stalled bounce shock, leading to the formation of a black hole within milliseconds2.
Pair-Instability Collapse in Massive Stars
For extremely massive stars, such as those in the Population III category with masses around 320 solar masses, the process can involve pair-instability collapse. This occurs when the star reaches a pair-instability region, causing a rapid collapse. In rapidly rotating stars, a fraction of the mass forms a torus around the remnant black hole, and hydrodynamical effects can drive outflows1. The remnant black hole in such scenarios can have a mass of approximately 130 solar masses1.
Direct Collapse Black Holes
Another pathway for black hole formation is the direct collapse scenario, which is particularly relevant in the early universe. This process involves the collapse of massive gas clouds in protogalaxies, which are prevented from fragmenting into stars by intense Lyman-Werner radiation. This radiation destroys molecular hydrogen (H2), which is crucial for cooling the gas and forming stars. As a result, the gas cloud collapses directly into a black hole without forming intermediate stars6. This scenario is supported by high-resolution hydrodynamical simulations that show the conditions necessary for such a collapse6.
Role of Primordial Black Holes
Primordial black holes (PBHs) can also influence the formation of the first stars and subsequent black holes. While PBHs with masses around 30 solar masses do not significantly alter the standard picture of first star formation, they can shift star formation to more massive halos and accelerate structure formation in regions with higher initial overdensities10. This can facilitate the formation of direct-collapse black holes by providing the necessary conditions for gas clouds to collapse without fragmenting10.
Observational Evidence and Gravitational Waves
The formation of black holes from massive stars can be accompanied by observable phenomena such as gravitational waves. For rapidly rotating massive stars, the collapse and subsequent black hole formation can generate gravitational waves detectable by ground-based detectors1. These observations provide crucial evidence for understanding the dynamics of black hole formation.
Conclusion
The transformation of a star into a black hole involves various pathways, including core collapse, pair-instability collapse, and direct collapse scenarios. The specific process depends on the star's mass, rotation, and environmental conditions. Observational evidence, such as gravitational waves, and theoretical models continue to enhance our understanding of these complex processes.
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Most relevant research papers on this topic
Black Hole Formation and Explosion from Rapidly Rotating Very Massive Stars
Rapidly rotating very massive stars can form black holes, with a torus surrounding the remnant BH and potential for observing gravitational waves using ground-based detectors.
A full general relativistic neutrino radiation-hydrodynamics simulation of a collapsing very massive star and the formation of a black hole
The 70 Msun star collapses into a black hole at a post-bounce time of 300 ms, significantly earlier than previously thought, with intense neutrino heating and violent convection reviving the stalled bounce shock.
Highly CitedImpact of supermassive black hole growth on star formation
Supermassive black hole growth in galaxies may regulate star formation through AGN feedback, but the exact details and timing of this feedback remain uncertain.
Highly CitedStar Formation Around Supermassive Black Holes
Star formation around supermassive black holes may be a repetitive process, resulting in multiple eccentric rings of young stars orbiting within a few tenths of a parsec of the galactic center.
Highly CitedFormation of the First Stars and Black Holes
The paper explores the formation of early stars and black holes, focusing on supermassive stars as potential precursors to direct collapse black holes, and their role in galaxy formation and reionization.
Rapid formation of massive black holes in close proximity to embryonic protogalaxies
Direct-collapse black holes can form in protogalaxies by avoiding star formation and preventing star fragmentation through strong ionizing background emission and a closely timed burst of star formation.
Highly CitedThe Black Hole-star Formation Connection Over Cosmic Time
Star formation in active galaxies with jets may first be enhanced, then suppressed, affecting the black hole-star formation connection over cosmic time.
Black-hole-regulated star formation in massive galaxies
Higher-mass central black holes in massive galaxies regulate star formation more efficiently, leading to earlier quenching and better understanding of baryonic processes within galaxies.
Rigorous JournalStar–disc interactions near a massive black hole
Stars in galaxies could be ground down into short-period orbits by interaction with a disc around a central massive black hole, potentially opening gaps or accreting material from the disc.
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