'); }
Artist’s schematic impression of the distortion of spacetime by a supermassive black hole at the centre of a galaxy. The black hole will swallow dark matter at a rate which depends on its mass and on the amount of dark matter around it. Image: Felipe Esquivel Reed.

Astronomers Find Black Holes Do Not Absorb Dark Matter

Article Updated: 24 Dec , 2015

by

[/caption]

There’s the common notion that black holes suck in everything in the nearby vicinity by exerting a strong gravitational influence on the matter, energy, and space surrounding them. But astronomers have found that the dark matter around black holes might be a different story. Somehow dark matter resists ‘assimilation’ into a black hole.

About 23% of the Universe is made up of mysterious dark matter, invisible material only detected through its gravitational influence on its surroundings. In the early Universe clumps of dark matter are thought to have attracted gas, which then coalesced into stars that eventually assembled the galaxies we see today. In their efforts to understand galaxy formation and evolution, astronomers have spent a good deal of time attempting to simulate the build up of dark matter in these objects.

Dr. Xavier Hernandez and Dr. William Lee from the National Autonomous University of Mexico (UNAM) calculated the way in which the black holes found at the center of galaxies absorb dark matter. These black holes have anything between millions and billions of times the mass of the Sun and draw in material at a high rate.

The researchers modeled the way in which the dark matter is absorbed by black holes and found that the rate at which this happens is very sensitive to the amount of dark matter found in the black holes’ vicinity. If this concentration were larger than a critical density of 7 Suns of matter spread over each cubic light year of space, the black hole mass would increase so rapidly, hence engulfing such large amounts of dark matter, that soon the entire galaxy would be altered beyond recognition.

“Over the billions of years since galaxies formed, such runaway absorption of dark matter in black holes would have altered the population of galaxies away from what we actually observe,” said Hernandez

Their work therefore suggests that the density of dark matter in the centers of galaxies tends to be a constant value. By comparing their observations to what current models of the evolution of the Universe predict, Hernandez and Lee conclude that it is probably necessary to change some of the assumptions that underpin these models – dark matter may not behave in the way scientists thought it did.

There work appears in the journal Monthly Notices of the Royal Astronomical Society.

The team’s paper can be found here.

'); }

,



Sort by:   newest | oldest | most voted
Kawarthajon
Member
Kawarthajon
March 22, 2010 5:27 AM

This is incredible. I asked this question – does dark matter get absorbed by black holes – on the Astronomy Cast podcast a while ago and the answer was yes, which appears to have been the common thinking at the time. The fact that it does not get absorbed really boggles the mind – if the only way we can detect this matter is through its gravitational pull, how can it not itself be effected by the strongest source of gravity in our galaxy?

ZomZom
Member
ZomZom
March 22, 2010 5:42 AM

I’m curious as to how the dark matter was modeled in this simulation. Assuming the model is valid, this finding would seem to lend credence to the suspicion that dark matter is merely the result of our failure to fully understand gravity.

The Eclectic Exterminator of Stupid Electricians
Member
The Eclectic Exterminator of Stupid Electricians
March 22, 2010 6:04 AM
Probably a dumb question, but do neutrinos pass through black holes too, or are they captured. So what you are saying here, if I, say, had a beam of streaming dark matter particles, it would pass through a black hole? Here dark matter only exude gravitation, but oddly, is not affected by the strong gravitational source of the black hole (to be captured) or even knows the mass of the black hole is there? Really sounds more like something akin to quantum mechanics to me! Hard to wrap one’s head around I think! [Free thinking suggests that dark matter particles might be few in number but are many parsecs across, or that they have properties quite foreign to… Read more »
The Eclectic Exterminator of Stupid Electricians
Member
The Eclectic Exterminator of Stupid Electricians
March 22, 2010 6:55 AM
I don’t like to say it, but there is a possibility that the idea of inactions between neutrinos, dark matter and dark energy or where dark matter is coupled with dark energy. Not only would this have consequences for cosmology, but it would also have problems with interactions with large and strong gravitational sources. Such ideas have been discussed in the literature, like in the Brookfield, et.al. paper Cosmology with massive neutrinos coupled to dark energy” (2005) It is all really heavy stuff, and I don’t quite 100% grasp the importance of this, but it explains what seem to be mass variances in neutrinos or odd observed energy / flux changes in neutrinos from different gravitational sources. As… Read more »
The Eclectic Exterminator of Stupid Electricians
Member
The Eclectic Exterminator of Stupid Electricians
March 22, 2010 6:59 AM

Sorry, one important error here.

I said;

“As the magnitudes of the masses of neutrinos and the vacuum energy density that likely creates the dark matter are similar, implies they may interact.”

I should have said “dark energy” NOT “dark matter, here.

Sorry!

ND
Member
ND
March 22, 2010 8:33 AM

OMG! OMG! Black holes *and* dark matter, at the same time! Two “fictitious” “things” being computer simulated at the same time. This will make any EU/PC person’s brain go explody and stuff.

I try not to tease EU/PC people before they arrive but I could not help it here. Sorry.

Dark Gnat
Member
Dark Gnat
March 22, 2010 8:47 AM

I never thought of dark matter particles as being several parsecs wide. That might be an interesting way to look at them.

Still, DM must be some tricky sfuff if it can influence regular matter gravitiationally, but not be influenced by it. Doesn’t this beak a law of physics or two?

markcasazza
Member
March 22, 2010 8:47 AM

Maybe it’s just me, but it seemed obvious from the first lecture I heard on dark matter that to be where it is theorized to be and to impact galaxies as it is theorized to it must be self repellent and this limits the density of dark matter in any location. Otherwise , since it is agnostic to other forces it would congregate at the center of galaxies and not in their halos. This observation reinforces that idea.

Olaf
Member
Olaf
March 22, 2010 9:21 AM

I am wondering if this dark matter is not some ripples in space-time. Mass bends spacetime, but maybe space-time ripples cased by some events long time ago could mimic this appearence of dark matter.

Aodhhan
Member
Aodhhan
March 22, 2010 9:41 AM
They aren’t saying black holes don’t consume dark matter, they are saying they don’t consume as much of it, if there is a large concentration within 1 cubic lightyear of it. Which itself is strange… since I’m not aware of any black hole which reaches out a cubic lightyear to pull in material. The consistency of dark matter probably isn’t dependent upon the black holes in the center of a galaxy, but rather all the matter near the center of a galaxy, which for many galaxies would be consistent. To say a black hole would grow to a rediculous size if it consumed all of the dark matter is a bit rediculous, since there is no way it… Read more »
mgmirkin
Member
March 22, 2010 9:44 AM

@ ND: Your sarcasm is underwhelming. What has your comment to do with anything whatsoever in this article? Typical pseudo-skeptical nonsense.

Shouldn’t you be elsewhere picking the wings off flies or something?

Greg
Member
Greg
March 22, 2010 9:46 AM
This makes no sense whatsoever. If dark matter consists of particles and exert gravitational influence on their surroundings then why can’t gravity act upon it and suck it into a black hole like ordinary matter? Isn’t there supposed to be an equal and opposite reaction to every action? I like the idea that dark matter may consist of filaments too large to get pulled into the black hole. I don’t see how dark matter can be self-repelling. It would mean that it carries something akin to an electrical charge and it has to be electically inert by definition. What do string theorists have to say on this? This should be good fodder for them. The easiest explanation is… Read more »
Lenard Lindstrom
Member
Lenard Lindstrom
March 22, 2010 10:06 AM

It is too early to suppose radical new properties of physics from one paper that suggests dark matter densities never exceeded 7 solar masses per cubic light year around super massive black holes. Dark matter halos do not behave like gas clouds. For instance, dark matter particles will rarely, if ever, collide with anything, so there is no mechanism for a halo to collapse. And if dark matter density did exceed the critical threshold in the early universe, one can suggest that super massive black holes first formed after the density dropped below the critical value. This paper may constrain models of the early universe, but I am sure it will take more to invalidate general relativity.

ND
Member
ND
March 22, 2010 10:09 AM

@mgmirkin: “Your sarcasm is underwhelming. ”

and you responded to it?

Excalibur
Member
Excalibur
March 22, 2010 10:12 AM
If dark matter are made of exotic particles, the intrinsic heat-component may have something to do. Since dm isnt expected to interact electromagnetically this ‘gas’ would not heat nor cool down in any traditional manner. If that gas is hot to start with (particles moving in an average speed comparable with galaxy escape speed, but below cluster escape speeds) then dm would not settle down inside galaxies. Self-anihilation is another possible aspect, whenever dm would increase density, it would also start to anihilate faster. Possibly being part of the energy source for the accretion disc. Either way, these notions are not in any way new. The articles conclusion that dm is not the major component of black hole… Read more »
SteveZodiac
Member
SteveZodiac
March 22, 2010 10:58 AM

So the concept of gravitic attraction being mutual between two bodies has now been modified. Dark matter attracts baryonic matter more than the other way round. What shall we call this then, Dark anti-gravity?

DrFlimmer
Member
DrFlimmer
March 22, 2010 11:25 AM

Some already mentioned that DM should also have some kind of angular momentum. But since cannot get rid of it (at least in no way that we know of), it cannot fall into any gravitational well, even if it is a black hole.

So, I think it is not that disturbing that a BH cannot suck down DM. It is difficult enough for a black hole to suck down normal matter (accretion disk, OMG!), and with DM it should be naturally harder!

Olaf
Member
Olaf
March 22, 2010 11:35 AM

@Aodhhan

“Which itself is strange… since I’m not aware of any black hole which reaches out a cubic lightyear to pull in material.”

Aodhhan, you do realize that gravity does not stop after 1 light year?

LID
Member
LID
March 22, 2010 11:54 AM
Sounds to me that DM may not exist entirely in our universe and therefore doesn’t have to play by entirely by our rules… M-Theory 101… We see its influence due to supergravity but that’s all we see. The same goes for Dark Energy and the Dark Flow. They don’t exist entirely within our universe, we just see the results. If all matter and energy can be reduced to plank length strings (not vibrating particles), and all strings vibrate a specific and quantifiable way in our 11-D continuum to define OUR universe… Then you have to ask what happens when all of those vibrations (or frequencies – which I like better) don’t exactly match. You can get things like… Read more »
Greg
Member
Greg
March 22, 2010 11:30 PM
Ok, some really fundamental questions are coming to mind here. Using the relativity model if dark matter exerts gravitational influence it must apply not just to ordinary matter, but to itself as well. Things that warp space-time tend to clump together over time, this is why there are black holes in the first place. So if dark matter anihilates itself when it contacts itself then this would keep concentrations down and should release measurable energy. But then why is there any dark matter left 13 billion years after the big bang? If it tends to clump together due to gravity and then anihilate itself when it does, it should be long gone by now (like how anti-matter is… Read more »
wpDiscuz
Become a Patreon and be a member of our club.