Nuclear reactions in AGN accretion disk

In summary, accretion disks around black holes consist of atomic material with high orbital velocities and density, but the disk is relatively cool due to the smooth inward spiral of particles. The understanding of accretion disks is not currently fully agreed upon, and it is not possible for fusion to occur within the disk itself. However, there is potential for fusion to occur if the black hole grows larger and disrupts nearby stars.
  • #1
gleb
1
0
As I understand it, it's all atomic material in the accretion disk of a big black hole, with very high orbital velocities and high density. However, the the disk is quite flat, and cooler than one would think with the velocities involved, because the material is swirling in smoothly, with individual particles having fairly tame velocities relative to nearby particles.

Now, I have two questions, really. First, does my understanding of the very basic properties of accretion disks agree with the currently accepted models? And second, is it possible for fusion to occur in the inner area of the disk? I know that the temperature of the gas is only on the order of x-ray emission, too cool for fusion, but what if there was some sort of perturbation in the disk, something that disrupted it's very smooth inward spiral. To me it seems like with the densities and energies involved, it would be a good environment for nuclear fusion. So, is there any merit to this idea?
 
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  • #2
It would depend on the size of the black hole and the density of the material in the accretion disc. White dwarfs can have bursts of surface fusion if fed from a companion star so I see no reasons why some black holes will not have fusion explosions in ther accretion discs. They can also disrupt stars by tidal stretching and possibly expose fusion areas.

The bigger the black hole gets the "softer" and less likely that events like this will happen as it accretes
 
  • #3
gleb said:
Now, I have two questions, really. First, does my understanding of the very basic properties of accretion disks agree with the currently accepted models?

Which one? Unfortunately, we don't have a consensus accretion disk model at the moment. The situation you describe is consistent with simplest "thin disk" models that don't involve MHD or radiation pressure.


And second, is it possible for fusion to occur in the inner area of the disk?

The disk itself isn't dense enough to undergo nuclear fusion. Novae (runaway fusion reactions) can occur when disk material impacts the degenerate surface of a white dwarf, but the lack of a surface means you won't get this behavior with a black hole.
 

What are nuclear reactions in AGN accretion disk?

Nuclear reactions in AGN accretion disk refer to the fusion of atomic nuclei, typically hydrogen, into heavier elements under extremely high temperatures and pressures. This process releases huge amounts of energy and is responsible for the luminosity of active galactic nuclei (AGNs).

How do nuclear reactions in AGN accretion disk occur?

Nuclear reactions in AGN accretion disk occur due to the intense gravitational pull of the supermassive black hole at the center of the disk. As matter is pulled towards the black hole, it becomes heated and compressed, triggering nuclear fusion reactions.

What types of nuclear reactions occur in AGN accretion disk?

The most common nuclear reaction in AGN accretion disk is the fusion of hydrogen nuclei into helium, known as the proton-proton chain. Other reactions may also occur, such as the carbon-nitrogen-oxygen cycle, depending on the temperature and density of the disk.

What is the role of nuclear reactions in AGN accretion disk in powering AGNs?

Nuclear reactions in AGN accretion disk are the primary source of energy for AGNs. The fusion of atomic nuclei releases immense amounts of energy in the form of radiation, which can be observed as the luminosity of AGNs.

How do nuclear reactions in AGN accretion disk affect the evolution of galaxies?

Nuclear reactions in AGN accretion disk play a crucial role in the evolution of galaxies. The intense radiation from AGNs can heat and ionize gas in the surrounding galaxy, affecting star formation and the overall structure of the galaxy. Additionally, the energy released from nuclear reactions can also drive powerful outflows, impacting the chemical composition and dynamics of the galaxy.

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