How do black holes form and what happens inside them?

Introduction

Black holes are regions in space where the gravitational pull is so strong that not even light can escape. They form through various mechanisms, including the collapse of massive stars, high-energy collisions, and the collapse of dark matter halos. Understanding the formation and internal structure of black holes is crucial for comprehending many astrophysical phenomena.

Key Insights

Formation through Stellar Collapse:
- Black holes can form from the collapse of massive stars, particularly those with initial masses greater than 40 solar masses, which may collapse directly into black holes without a supernova explosion.
Primordial Black Holes:
- Primordial black holes (PBHs) can form during the early universe through mechanisms such as the collapse of non-topological solitons during a first-order electroweak phase transition.
- PBHs can also form from the gravothermal collapse of self-interacting dark matter halos, leading to the creation of supermassive black holes (SMBHs) without the need for baryons or prior star formation.
High-Energy Collisions:
- Black holes can form in high-energy collisions when the gravitational field of one particle focuses another particle to a small impact parameter, resulting in the formation of a black hole if the impact parameter is smaller than the Schwarzschild radius .
Direct Collapse in Protogalaxies:
- Supermassive black holes can form directly in the nuclei of protogalaxies through the rapid loss of angular momentum in self-gravitating gas, leading to a dense core that collapses into a black hole.
Internal Structure and Evolution:
- The internal structure of black holes, particularly charged ones, is influenced by the mass and charge of the collapsing matter. Wormhole-like structures can form when the charge-mass ratio is small, but large curvatures develop due to mass inflation.
- Black holes emit particles due to quantum mechanical effects, leading to a slow decrease in mass and eventual evaporation. This process violates the classical law that the event horizon area cannot decrease but adheres to a generalized second law of thermodynamics.

Conclusion

Black holes form through various mechanisms, including the collapse of massive stars, high-energy collisions, and the collapse of dark matter halos. Primordial black holes can form in the early universe, and supermassive black holes can develop directly in protogalaxies. The internal structure of black holes is complex and influenced by factors such as mass, charge, and quantum mechanical effects, which can lead to phenomena like particle emission and mass inflation. Understanding these processes provides valuable insights into the nature and evolution of black holes.

How do black holes form and what happens inside them?

Summary

Introduction

Key Insights

Conclusion

Sources and full results

Particle creation by black holes

Quantum mechanical effects cause black holes to create and emit particles as if they were hot bodies, leading to their eventual disappearance and violation of the classical law of event horizon area not decreasing.

Internal structure of charged black holes

Charged black holes have a wormhole-like internal structure during formation, which remains stable during evaporation, and is insensitive to late-time perturbations.

How black holes form in high energy collisions

Black holes form in high-energy collisions when the gravitational field of one particle creates a gravitational shock wave, focusing the target particle to a smaller impact parameter, leading to a black hole.

Primordial black holes from an electroweak phase transition

Primordial black holes can form through a first-order electroweak phase transition, with potential dark matter candidates and experimental signals including gravitational waves and multi-lepton/jet final states.

Formation of supermassive black holes by direct collapse in pre-galactic haloes

Supermassive black holes can form directly in protogalaxies through rapid collapse in pre-galactic haloes, potentially providing the seeds for all present-day black holes.

Gravothermal collapse of self-interacting dark matter halos and the origin of massive black holes.

Gravothermal collapse in self-interacting dark matter halos leads to massive black hole formation, with no need for baryons, prior star formation, or other seed mechanisms.

Black hole formation in a box

In an insulated box in thermal equilibrium, black holes should form and evaporate in a statistically time-symmetric way, with adiabatical formation being more likely than Jeans instability.

Formation of a Black Hole in the Dark

High-mass stellar black holes may form promptly when massive stars disappear silently, without receiving an energetic trigger from a nearby supernova.

HOW BLACK HOLES FORM IN HIGH ENERGY COLLISIONS

Black holes form in high-energy collisions when the gravitational field of one particle creates a gravitational shock wave, focusing the target particle to a smaller impact parameter, and capturing the projectile when the impact parameter is smaller than its own Schwarzschild radius.

The role of black holes in galaxy formation and evolution

Black holes in galaxies can potentially halt star formation by heating and ejecting ambient gas, potentially impacting large elliptical galaxies.

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