Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: EvaH on 08/11/2018 15:51:58

Title: Is there any evidence of dark matter surrounding a black hole?
Post by: EvaH on 08/11/2018 15:51:58
Dean wants to know:

Is there any evidence of Dark Matter surrounding a Black Hole? What would happen to this dark matter if it started falling into a black hole?

Would there be a 'dark accretion disk' and a 'normal Gamma jet'?

Is there any evidence of 'Dark Quasars' i.e. Black Holes with no or a dark accretion disc but with Gamma Jets?


What do you think?
Title: Re: Is there any evidence of dark matter surrounding a black hole?
Post by: Janus on 08/11/2018 17:18:41
Since Dark matter density tends to be very low and Black hole density high, detecting DM around a black hole might be difficult as we would be limited to measuring it by gravitational lensing.
No accretion disk.   The disk shape formed by baryonic matter is caused by collisions between the particles themselves which requires an electromagnetic interaction between the particles.  DM doesn't interact electromagnetically, so there would be no mechanism to produce a disk ( the same thing happens with spiral galaxies, the luminous matter forms a disk shape, while the DM remains in a spherical volume.)
No jets either.  Jets are caused by ionized matter. to be ionized, you have to have a charge, and if you have a charge, you interact with the electromagnetic force.
DM doesn't interact electromagnetically. It wouldn't be forced into jet by the magnetic lines of the BH, nor will it emit any form of electromagnetic radiation ( the only possible exception for this is if DM had an equivalent Anti- dark matter particle. then mutual annihilation could produce gamma radiation. But  this type of reaction would be any more common near black holes then they would be any where else. And  DM is likely like regular matter in this one respect, where there is preponderance of regular matter over anti-matter)
The same holds for quasars; no baryonic matter, no jets, no radiation.
The only effect DM falling into a black hole would have is to increase the mass of the black hole.
Title: Re: Is there any evidence of dark matter surrounding a black hole?
Post by: guest46746 on 08/11/2018 17:41:27
Evidence is doubtful as black matter remains undetected. A BH is surrounded by S/T in an extreme state of excitation contained by gravity. Dark matter is antithetical to EM Radiation and Gravity. In the cosmic web, we may see evidence of Dark Matter, large areas of void, separating Galaxtic EM filiments. What is not seen in the large voids, possibly consisting of Dark Matter that surround and border EM filaments, are a single specks of EM light within a large void that  would stand out noticeably. What is seen are EM filaments stretched out as if by separtion from an unknown force. If science was to look for what you describe, Black Holes with no or a dark accretion disc but with Gamma jets, intuition would lead one to believe that such a powerful gamma jets would be detected in a large void, as a speck of EM Light standing out noticeably. lol.
Title: Re: Is there any evidence of dark matter surrounding a black hole?
Post by: yor_on on 13/11/2018 22:24:28
Well, there is with galaxies.
https://apod.nasa.gov/apod/ap030814.html

" In addition to the theoretical difficulties, there is at least one model-independent reason to think that no modification of gravity will ever replace the idea of dark matter: we seem to be accumulating evidence (tentatively at the moment, to be sure) for gravitational forces pointing in directions where there is no ordinary matter. The most basic such clue comes from studies of gravitational lensing of clusters of galaxies, which can be used to reconstruct the distribution of dark matter in the clusters. The upshot is that the dark matter seems to be distributed much more smoothly than the ordinary matter; see this reconstructed cluster image for an example. Less direct evidence is found in the acoustic peak structure of the temperature anisotropies in the cosmic microwave background. (For an intro, see Wayne Hu's tutorial.) Density fluctuations in the plasma of the early universe lead to sound waves, in which regions become more dense and therefore hot, and then bounce back and become less dense, in a repeating cycle; this leads to peaks in the plot of temperature fluctuation as a function of angular scale. But fluctuations in the dark matter don't heat up (they don't interact with light, since they're dark), so they only increase with time. Consequently, odd-numbered peaks have ordinary matter and dark matter in phase, and even-numbered peaks have them out of phase. The out-of-phase oscillations are suppressed, so we expect dark matter to boost the odd-numbered peaks. This is exactly what appears to happen, as this figure indicates. At least a little bit; the data need to improve before we can be sure. But it's hard to see how a modified theory of gravity could explain this phenomenon.  "  http://preposterousuniverse.blogspot.com/2004/05/was-einstein-wrong.html