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Is there a spatial or gravitational relationship between black holes and dark matter/energy?

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  • $\begingroup$ I suppose technically some MACHOs could be black holes, but certainly not supermassive ones, and MACHOs need to be lighter than astrophysically reasonable black holes in order to explain an appreciable fraction of dark matter anyway. $\endgroup$ – Stan Liou Mar 15 '15 at 0:35
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No, not really.

As Stan Liou hints at in his comment, massive objects such as black holes (BHs) were previously a candidate to dark matter (DM). But it can be shown that in order to explain the various problems that the existence of DM needs to solve, there would have to be so many, that their gravitational effect ("microlensing") on background sources would be much larger than what is observed. Today, most people think that DM is simply a particles with an extremely small interaction cross section, such that it virtually doesn't interact with other particles, except through gravitational attraction.

You also ask if there's any spatial relationship, and in a way you could say there is. Most, if not all, galaxies sport a supermassive BH, and these tend to lie in the center of the gravitational potential wells created by the galaxies' DM. "Normal" BHs, however, just float around like stars.

BHs also tend to grow by accretion of matter onto them, and of course they can also eat DM, so to some extend BHs also consist of DM. But since the DM doesn't interact, a DM particle would need to fly directly toward the BH, lest it would simply be deflected and escape. Normal matter, on the other hand, is slowed down by friction and spirals toward the BH. Thus, BHs consist mostly of normal matter. It doesn't really matter, though, since after something has fallen into a BH, everything but its mass, charge, and angular momentum will be forgotten.

Dark energy is something completely different, better described as a negative pressure which is a property of space itself. I think. Or we think. Nobody really knows. But it presence doesn't correlate with that of BHs or DM. Ten years ago, there was a hypothesis that a collapsing star should be converted into dark energy rather than a BH, causing a so-called dark-energy star, but I don't think anybody believes this anymore.

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No there is no known particular connection between black holes, dark matter and dark energy.

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    $\begingroup$ Not to be a pain, but this answer is pretty useless as it contains no explanation or justification. $\endgroup$ – Donald.McLean Mar 17 '15 at 12:14
  • $\begingroup$ I would say how can you explain or justify there not being a particular connection, especially when there isn't even an apparent connection between BH and DM + DE? $\endgroup$ – John Davis Mar 17 '15 at 18:56
  • $\begingroup$ Really? The other answer seems to have done a reasonably good job. $\endgroup$ – Donald.McLean Mar 17 '15 at 19:02

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