Are There Really Hundreds of Black Holes in NGC 6101?

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Discussion Overview

The discussion centers around the claim that NGC 6101 may contain hundreds of black holes, as suggested by computer simulations and recent observations. Participants explore the implications of this finding, including the rarity of black hole mergers and the potential influence of dark matter on the dynamics within the galaxy.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant expresses skepticism about the number of black holes in NGC 6101, questioning why there are not more recorded mergers by LIGO if so many exist.
  • Another participant suggests that even with hundreds of black holes, mergers could be extremely rare, potentially occurring only once every 100 billion years unless they form in binary systems.
  • A participant questions the absence of visible stellar collisions, noting that the density of stars is much greater than that of black holes.
  • Another participant raises a point about the detection limits of stellar collisions occurring 100 million light years away.
  • One participant introduces the idea that dark matter could play a significant role in the dynamics of NGC 6101, potentially affecting mass segregation among the stars and black holes.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the black hole population in NGC 6101, particularly regarding the frequency of mergers and the role of dark matter. There is no consensus on these points, and the discussion remains unresolved.

Contextual Notes

Participants highlight limitations in the detection of stellar collisions and the potential influence of dark matter, but these aspects remain unresolved and depend on various assumptions.

wolram
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I find this article hard to believe can there be so many Black Holes in one galaxy, if there are, why are there not many mergers recorded by Ligo.

https://www.sciencedaily.com/releases/2016/09/160907215155.htm

Computer simulations of a spherical collection of stars known as 'NGC 6101' reveal that it contains hundreds of black holes, until now thought impossible. Recent observations already found black hole candidates in similar systems, with this research enabling astrophysicists to map black holes in other clusters. These systems could be the cradle of gravitational wave emission, 'ripples' in the fabric of space-time
 
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Hundreds of black holes can still mean one merger per 100 billion years or something like that - unless they form in a binary system, mergers are extremely rare. Those black holes have a few times the mass of sun each, so LIGO won't have such a large detection range for them.
 
Why don't we see the sky alight with stellar collisions? After all, the styar density is much larger than the black hole density?
 
Well, which fraction of stellar collisions 100 million light years away do we detect?
 
I'm curious about the apparent lack of consideration for DM in NGC6101. I suspect a massive DM component could also suppress mass segregation. The arxiv version of the subject paper is: http://arxiv.org/abs/1609.01720, A stellar-mass black hole population in the globular cluster NGC 6101?.
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