New Hubble Observations Suggest Gap in Current Dark Matter Models (hubblesite.org) 27
Long-time Slashdot reader bsharma shares an announcement from NASA's Hubble Space Telescope site:
Researchers found that small-scale concentrations of dark matter in clusters produce gravitational lensing effects that are 10 times stronger than expected. This evidence is based on unprecedently detailed observations of several massive galaxy clusters by NASA's Hubble Space Telescope and the European Southern Observatory's Very Large Telescope (VLT) in Chile...
Priyamvada Natarajan of Yale University in New Haven, Connecticut, one of the senior theorists on the team, added, "There's a feature of the real universe that we are simply not capturing in our current theoretical models. This could signal a gap in our current understanding of the nature of dark matter and its properties, as these exquisite data have permitted us to probe the detailed distribution of dark matter on the smallest scales."
The team's paper will appear in the September 11 issue of the journal Science... This unexpected discovery means there is a discrepancy between these observations and theoretical models of how dark matter should be distributed in galaxy clusters.
It could signal a gap in astronomers' current understanding of the nature of dark matter.
Priyamvada Natarajan of Yale University in New Haven, Connecticut, one of the senior theorists on the team, added, "There's a feature of the real universe that we are simply not capturing in our current theoretical models. This could signal a gap in our current understanding of the nature of dark matter and its properties, as these exquisite data have permitted us to probe the detailed distribution of dark matter on the smallest scales."
The team's paper will appear in the September 11 issue of the journal Science... This unexpected discovery means there is a discrepancy between these observations and theoretical models of how dark matter should be distributed in galaxy clusters.
It could signal a gap in astronomers' current understanding of the nature of dark matter.
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All matter matters!
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Interesting (Score:5, Informative)
Explaining this difference requires the existence of a larger number of compact substructures in the inner regions of simulated clusters. Baryons and dark matter are expected to couple in the dense inner regions of sub-halos, leading to alterations in the small-scale density profile of dark matter, it could be that our current understanding of this interplay is incorrect. Alternatively, the difference could arise from incorrect assumptions about the nature of dark matter.
So among other confounding factors that they have ruled out, or ruled as having insufficient influence, it could just be a less interesting aspect of gravitational coupling between regular and dark matter in observations vs. simulations instead of a clear observation of a new aspect of dark matter.
Easy fix (Score:4, Funny)
Just add more epicycles or dimensions to string theory.
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I can't fathom how so many people have never in their lives even so much as heard of "deductive reasoning"... It is mind boggling to behold.
If someone cut a square out of a piece of paper, but left me the piece of paper now having a hole, I don't need to see the piece cut out to deduce information about it.
The paper with the hole sitting there is exactly the evidence proving your claim wrong. You keep saying the piece cut out can't possibly exist, and isn't possible to know anything about.
How? Why?
It is
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No it was his ignoring observational evidence.
He comes into every story with "dark matter" in the headline, and copy/pastes the same shit to farm mod points.
People like that don't deserve to benefit from everything science has enabled mankind to do if all he's going to do is denounce all of it.
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Wow! Epicycles and String Theory really puts a kink in your...trachea. Bet you are a riot at the office Christmas Party.
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I can't fathom how so many people have never in their lives even so much as heard of "deductive reasoning"... It is mind boggling to behold.
If someone cut a square out of a piece of paper, but left me the piece of paper now having a hole, I don't need to see the piece cut out to deduce information about it.
I don't need to meet you to know that you're a real pain in the ass.
We aren't trying to figure out the shape of the hole, we're trying to figure out where the hole came from. Like the hole in your head, we know how big it is.
Re:Easy fix (Score:4, Funny)
I don't know shit but (Score:1)
If the gravity is higher in small clusters than expected could it be lower / negative in other places to together match up with what we saw before but maybe also explain why the universe expands since we had missed a lot of repelling energy/matter?
Back with the boson and shit I had something I wanted to ask someone in the know but I forgot what it was.
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The clusters generally have a lot of (positive) gravity. And the discrepancies are for "smaller-scale arcs and distorted images nested within the larger-scale lens distortions in each cluster's core", i.e. for central parts of the clusters where the gravity is stronger than expected (it is expected to be bigger there, though it is even bigger).
If it were about whole clusters then yes, we could think about nega
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I hope that this can be used as a toilet paper for that thing you know :-)
You wanna have a wank and cum into a galactic cluster?
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Some galaxies have mischievous aliens and some don't. No need to bring dark energy into this. If it helps, they can be elves for you.
What I want to know is (Score:3)
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Black holes full of dark mater? (Score:2)
Dark matter doesn't interact with baryonic matter, except gravitationally. OK, fine. Does it interact non-gravitationally with other dark matter? Who knows? Maybe, maybe not.
It would, of course, interact with other dark matter gravitationally. And that means that it can fall into clusters if its particles can lose their relative velocities. Harder to do without other interactions to provide friction, but still possible.
But once it's clustering, if enough of it clustered it would form a black hole just
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Once a black hole is formed, all that matters is mass, angular momentum, and net charge.
And (if dark matter has one or more long-range dark-matter/dark-matter interaction forces, as baryonic matter has electric charge), the "charge" analog(s) for that/those force(s).
Should Enhance Ability to Detect Dark Matter (Score:2)
Evidently, gravity is not the only influence Dark Matter has on regular matter or at least photons. Either it has an innate ability to bend light or it harbors other kinds of matter that does.. meaning it interacts with some kinds of matter.. well, I suppose it could just be pulling some kinds of matter in by means of gravity ... something that bends light.
Either way -- this bending of light could be very helpful in finding the boundries of where dark matter is.
--Matthew
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Gravity is a geometrical property of space(time), and it causes itself the bending of light. It was even one of the first tests of general relativity [wikipedia.org].
And regarding use of light bending for detecting amounts of dark matter: that is exactly what they did and what is used already for a long time. Here it was used with a finer precision.