How Do Accretion Discs and Black Holes Emit High-Velocity Charged Particles?

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Discussion Overview

The discussion revolves around the mechanisms by which accretion discs and black holes emit high-velocity charged particles. Participants explore concepts related to gravitational effects, energy release during accretion, and the nature of radiation emitted from these regions, touching on both theoretical and observational aspects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that the gravity of black holes is comparable to that of other massive objects at large distances, questioning whether black holes are fundamentally different.
  • Others argue that the intense gravity of black holes creates conditions where no known form of energy can escape once matter crosses the event horizon.
  • One participant mentions Hawking radiation, suggesting that particle-antiparticle pairs are created in the energy field surrounding black holes, with one particle escaping while the other falls in.
  • Another viewpoint suggests that energy is released as gas particles fall into the black hole, converting gravitational potential energy into kinetic energy, leading to X-ray emissions from the accretion disk.
  • Concerns are raised about the applicability of analogies to nuclear fusion when discussing energy release during accretion, with a participant noting that not all matter falling into a black hole necessarily emits radiation.
  • Discussion includes the idea that jets of charged particles emitted at right angles to the accretion disk may be related to magnetic fields, though the exact mechanisms remain uncertain.

Areas of Agreement / Disagreement

Participants express multiple competing views on the nature of gravity in relation to black holes, the mechanisms of energy release during accretion, and the role of Hawking radiation. The discussion remains unresolved with no consensus on these points.

Contextual Notes

Participants highlight limitations in understanding the mechanisms of energy emission, the dependence on definitions of energy and gravity, and the speculative nature of certain theoretical calculations related to Quantum Gravity.

verdigris
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The gravity of black holes is the same as the gravity of other objects at large distances.Are black holes really just the same as everything else?
When an atomic nucleus forms from protons and neutrons energy is released, because, if it is not,then energy would not have to be put into the nucleus to break up the nucleus, and the nucleus would not be stable.So when some gas from an accretion disc goes into a black hole,increasing the mass of the black hole wouldn't we expect energy to be given out as this happens.
Is this what gives the charged particles emitted at right angles to the disc their high velocities?
 
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I'm confused. How is the gravity of any other universal object even comprable to the intense gravity of a black hole? Also, from what I've studied, once matter falls past the event horizon and into the singularity, gravity becomes so intense that no known form of energy can escape.
 
hawking energy is emitted from the black hole
 
Lionell

I think that the atoms do release energy and light, but this energy and this light
will disappear in the black hole leaving no trace that it happened.
 
paul_peciak said:
hawking energy is emitted from the black hole

in the energy field sourronding the BH, particle - antiparticle pairs are created, before annihilation, one of the partners is emitted in the direction of the BH and the other escapes. So it is not that the particle is escaping FROM the black hole...
 
I think the radiation from accretion disks around black hole is emitted due to acceleration of the gas particles that fall into the black hole. In Newtonian mechanics we would say that gravitational potential energy turns into kinetic energy of the particles. The falling gas gets hotter and soon starts emmiting X rays. Since the emission happens outside of the black hole horizon, there is no problem for it to escape and reach us.

That has nothing to do with Hawking radiation which is too weak to be observable and frankly speaking is just a speculative calculation in a semi-classical approximation to Quantum Gravity. Since we don't have theory of Quantum Gravity, we can't be 100% sure that calculation is correct.
 
Last edited:
verdigris said:
The gravity of black holes is the same as the gravity of other objects at large distances.Are black holes really just the same as everything else?
When an atomic nucleus forms from protons and neutrons energy is released, because, if it is not,then energy would not have to be put into the nucleus to break up the nucleus, and the nucleus would not be stable.So when some gas from an accretion disc goes into a black hole,increasing the mass of the black hole wouldn't we expect energy to be given out as this happens.

Your analogy to fusion is somewhat inappropriate, I think, since heavier nuclei will actually require energy input to fuse. Dropping a solid object into a black hole will not necessarily produce any radiation. If the tidal field of the black hole doesn't bend or break it, then it can pass the event horizon without extra energy emission.


Is this what gives the charged particles emitted at right angles to the disc their high velocities?

Are you referring to jets? These are thought to be the result of magnetic fields in the accretion disk, though the exact mechanism is still very uncertain. Most of the radiation emitted from the vicinity of black holes comes from the gas disk surrounding it. The mechanisms for emission are many and varied (e.g. thermal, synchrotron, inverse compton scattering).
 

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