Dark matter mystery deepens

Oct 17, 2011
This artist's conception shows a dwarf galaxy seen from the surface of a hypothetical exoplanet. A new study finds that the dark matter in dwarf galaxies is distributed smoothly rather than being clumped at their centers. This contradicts simulations using the standard cosmological model known as lambda-CDM. Credit: David A. Aguilar (CfA)

(PhysOrg.com) -- Like all galaxies, our Milky Way is home to a strange substance called dark matter. Dark matter is invisible, betraying its presence only through its gravitational pull. Without dark matter holding them together, our galaxy's speedy stars would fly off in all directions. The nature of dark matter is a mystery -- a mystery that a new study has only deepened.

"After completing this study, we know less about dark matter than we did before," said lead author Matt Walker, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics.

The standard cosmological model describes a universe dominated by and dark matter. Most astronomers assume that dark matter consists of "cold" (i.e. slow-moving) exotic particles that clump together gravitationally. Over time these dark matter clumps grow and attract normal matter, forming the galaxies we see today.

use powerful computers to simulate this process. Their simulations show that dark matter should be densely packed in the centers of galaxies. Instead, new measurements of two show that they contain a smooth distribution of dark matter. This suggests that the standard cosmological model may be wrong.

"Our measurements contradict a basic prediction about the structure of in dwarf galaxies. Unless or until theorists can modify that prediction, cold dark matter is inconsistent with our ," Walker stated.

Dwarf galaxies are composed of up to 99 percent dark matter and only one percent normal matter like stars. This disparity makes dwarf galaxies ideal targets for astronomers seeking to understand dark matter.

Walker and his co-author Jorge Peñarrubia (University of Cambridge, UK) analyzed the dark matter distribution in two neighbors: the Fornax and Sculptor dwarf galaxies. These galaxies hold one million to 10 million stars, compared to about 400 billion in our galaxy. The team measured the locations, speeds and basic chemical compositions of 1500 to 2500 stars.

"Stars in a dwarf galaxy swarm like bees in a beehive instead of moving in nice, circular orbits like a spiral galaxy," explained Peñarrubia. "That makes it much more challenging to determine the distribution of dark matter."

Their data showed that in both cases, the dark matter is distributed uniformly over a relatively large region, several hundred light-years across. This contradicts the prediction that the density of dark matter should increase sharply toward the centers of these galaxies.

"If a dwarf galaxy were a peach, the standard says we should find a dark matter 'pit' at the center. Instead, the first two dwarf galaxies we studied are like pitless peaches," said Peñarrubia.

Some have suggested that interactions between normal and dark matter could spread out the dark matter, but current simulations don't indicate that this happens in dwarf galaxies. The new measurements imply that either normal matter affects dark matter more than expected, or dark matter isn't "cold." The team hopes to determine which is true by studying more dwarf galaxies, particularly galaxies with an even higher percentage of .

The paper discussing this research was accepted for publication in The Astrophysical Journal and is available online.

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Pyle
3.5 / 5 (11) Oct 17, 2011
I wonder how long it will take all of the alternate gravity theories to publish explanations for dwarf clusters without the CDM.
Should be exciting!
My sporadically educated guess:
- EU will be first to offer an explanation.
- Zephyr already knew this and AWT naively can solve any problem.
- The LCDM models will be appropriately adjusted to explain why they put the DM plug in the wrong place.
- Finally, 6-12 months from now, the numbers will be crunched in Toronto and Moffat's MOG will still fit, elegantly.
Digi
3 / 5 (14) Oct 17, 2011
'Dwarf galaxies are composed of up to 99 percent dark matter and only one percent normal matter like stars.' Or perhaps dark matter doesn't exist and some other process is at work?
Deadbolt
4.8 / 5 (12) Oct 17, 2011
Well, Dark Matter is just a stand in name for unexplained mass, but we'll have to find out.
MrVibrating
2.5 / 5 (4) Oct 17, 2011
If stellar motions in dwarf galaxies are chaotic and in spiral galaxies the stars.. 'spiral' in towards the central black hole, then the hypothesis that stars drag dark matter along, imparting some KE to it, seems entirely consistent with the findings. Why then is this intepretation rejected (if i understand correctly)?
typicalguy
3.8 / 5 (4) Oct 17, 2011
Most alternative theories can't account for the gravitational lensing. MOND would be interesting if it could account for lensing....oh and the "small" problem that gravity is a force that would effect all galaxies of roughly equal size the same BUT the amount of dark matter in galaxies has been measured to differ from one galaxy to another. If it could be determined what a dark matter particle is, it would allow us to move beyond the standard model. Unless of course it is a bunch of black holes or ordinary matter. Of course, I'd its black holes, that would allow for better modeling of the universe.
TimESimmons
1.4 / 5 (8) Oct 17, 2011
So simulations of dark matter don't match observations, and dark matter appears to stay spread out at low density.

Here's why:-

http://www.presto...ndex.htm
Isaacsname
3.7 / 5 (15) Oct 17, 2011
I predict this article will result in a long slew of comments that range from god to bellybutton lint to politics to cosmology, tempered with a dose of snark, all of which I am looking forward to gleefully.

Carry on without me gentlemen, my work is done here.
Ramael
3.9 / 5 (9) Oct 17, 2011
... Or perhaps dark matter doesn't exist and some other process is at work?


I agree with Deadbolt, dark matter refers to the unknown process at work. Maybe what Digi is trying to imply is that dark matter might not be comprised of particles in the sense that modern science is attempting to apply.. which is also what this article is kind of getting at..
Callippo
1.4 / 5 (11) Oct 17, 2011
This contradicts the prediction that the density of dark matter should increase sharply toward the centers of these galaxies.
Such finding would contradict most of previous observations of dark matter by rotational curves of stars inside of galaxies. It would violate the way, in which dark matter was revealed originally by Zwicky. In dense aether model the dark matter is attracted rather to areas of negative surface curvature, being really formed with substantial amount of dark matter (antineutrino and positrons). Antimatter is repulsing mutually, but it's attracted to negative space-time curvatures around normal matter.

http://www.aether...ion3.gif

.. and AWT naively can solve any problem..
IMO the ratio of matter and antimatter inside of dark matter around galaxies could vary in wide range. It's not so easy to say, whether the dark matter will surround some particular galaxy or penetrate it deeply.
Callippo
1.3 / 5 (10) Oct 17, 2011
We could say schematically, the heavier particles of antimatter will be, the more they will become similar to particles of matter. The matter-antimatter symmetry is violated substantially only for most lightweight particles, like the neutrinos. The larger galaxy is, the heavier particles it should contain, the more the dark matter will penetrate into it. But it's just a rough estimation and we probably ignore many circumstances, which could reverse this dependency.

But it cannot change the fact, that the dark matter has been found just by rotational curves of stars at the OUTER areas of galaxies. If someone expects most of dark matter INSIDE of galaxy, then he is probably not familiar with the whole history of dark matter finding.

But I'd rather say, the scientific journalism took a place here. Many physicists today tend to pretend, their finding is more fundamental, then it really is for the sake of grant support - and the journalists support them in this approach naturally.
binghamjames
1 / 5 (1) Oct 17, 2011
This Explains it all in a Nut Shell http://www.whatis...o-world/
mpc755
1.3 / 5 (9) Oct 17, 2011
'"After completing this study, we know less about dark matter than we did before," said lead author Matt Walker, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics.'

"Cosmologists use powerful computers to simulate this process. Their simulations show that dark matter should be densely packed in the centers of galaxies. Instead, new measurements of two dwarf galaxies show that they contain a smooth distribution of dark matter. This suggests that the standard cosmological model may be wrong."

Which is evidence the aether is an incompressible superfluid with properties of a solid.

'Phenomenology of Gravitational Aether as a solution to the Old Cosmological Constant Problem'
arxiv.org/abs/1106.3955

"One proposal to address this puzzle at the semi-classical level is to decouple quantum vacuum from space-time geometry via a modification of gravity that includes an incompressible fluid, known as Gravitational Aether."
SemiNerd
4.5 / 5 (8) Oct 17, 2011
I wonder how long it will take all of the alternate gravity theories to publish explanations for dwarf clusters without the CDM.
Should be exciting!
My sporadically educated guess:
- EU will be first to offer an explanation.
- Zephyr already knew this and AWT naively can solve any problem.
- The LCDM models will be appropriately adjusted to explain why they put the DM plug in the wrong place.
- Finally, 6-12 months from now, the numbers will be crunched in Toronto and Moffat's MOG will still fit, elegantly.

Moffat's MOG doesn't explain many things that dark matter explains quite well. DM is still the theory to beat.
RayInLv
3.5 / 5 (4) Oct 17, 2011
Ok, may be it's not Dark Matter. Ever since the term has been coined, it has been used to explain this perceived gravitational disparity. Could just be it is stronger in some places than we think, for reasons we can not explain, and by attributing it to Matter, we are putting a lense on the creative thinking needed in order to arrive at a complete explanation.
Deesky
4.6 / 5 (9) Oct 17, 2011
Moffat's MOG doesn't explain many things that dark matter explains quite well. DM is still the theory to beat.

Quite right. MOG is just an ad hoc modification of gravity that seems to work in some cases, but doesn't explain lensing and is incompatible with general relativity too, so Moffat's been tinkering with GR to try and make it fit. I don't think anyone really places much credence in it in the scientific community.

As for DM distributions, I always thought that DM didn't form core-like clumps, but were more loosely coupled distributions. One thing to consider might be that these dwarf galaxies are crashing/spiraling into the milky way and thus exchanging matter which might also have an effect on their respective DM distributions.

Anyway, interesting observations. I look forward to further research.
omatumr
1.3 / 5 (24) Oct 17, 2011
Dark matter is invisible, betraying its presence only through its gravitational pull.


Our infinite, cyclic Universe [1-4] has been explained by using nuclear rest mass data and cross-sections to explain observations, without Modern "Black Magic":

No Big Bang
No Dark Matter
No Dark Energy
No Oscillating Neutrinos

1. "Is the Universe Expanding?" The Journal of Cosmology 13, 4187-4190 (2011)

http://journalofc...102.html

2. "Origin and Evolution of Life", Journal of Modern Physics 2, 587-594 (2011)

http://dl.dropbox...5079.pdf

3. "Neutron Repulsion", The APEIRON Journal, in press (2011)

http://arxiv.org/...2.1499v1

4. "Video Summary of Research Career (1961-2011"

http://dl.dropbox...reer.pdf

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
http://myprofile....anuelo09
omatranter
3.5 / 5 (21) Oct 18, 2011
Our infinite, cyclic Universe has been explained by using nuclear sleeping mass data and cross-sections to complain about observations, without Modern "Black Magic" just a little of the Voodoo that I do So well.

To sum up I:
Have No Clue
Can not take a hint
23 skidoo
Have a dropbox full of poo

You will have no choice but to believe me when my comrades from Atlantis return on December 12 2012, due to Global Warming induced sea rise causing the Oceans to recede due to the ensuing Ice-age, the Illuminati will quake in their boots and the Brandenburg orchestra will only play bum notes
theon
1.7 / 5 (6) Oct 18, 2011
The authors would know more about dark matter (instead of less) if they would discuss with their own colleague Rudy Schild. He detected in 1996 that what they call dark matter is actually normal matter that did not make it into stars. There are many MACHOs, small Jupiters, of earth weight and solar size. The strange cold dark matter can not exist, because if it did, our Galaxy would look different, as the present author prove once more.
Pkunk_
3.9 / 5 (7) Oct 18, 2011
You will have no choice but to believe me when my comrades from Atlantis return on December 12 2012, due to Global Warming induced sea rise causing the Oceans to recede due to the ensuing Ice-age, the Illuminati will quake in their boots and the Brandenburg orchestra will only play bum notes


That is one brilliant paragraph! LMAO
MarkyMark
3 / 5 (4) Oct 18, 2011
You will have no choice but to believe me when my comrades from Atlantis return on December 12 2012, due to Global Warming induced sea rise causing the Oceans to recede due to the ensuing Ice-age, the Illuminati will quake in their boots and the Brandenburg orchestra will only play bum notes


That is one brilliant paragraph! LMAO

Sadly that Paedo probably believes it afterall he claims the sun has a Neutron Star inside it!!!
jsdarkdestruction
4.5 / 5 (8) Oct 18, 2011
You will have no choice but to believe me when my comrades from Atlantis return on December 12 2012, due to Global Warming induced sea rise causing the Oceans to recede due to the ensuing Ice-age, the Illuminati will quake in their boots and the Brandenburg orchestra will only play bum notes


That is one brilliant paragraph! LMAO

Sadly that Paedo probably believes it afterall he claims the sun has a Neutron Star inside it!!!

look closely at the name. lol. its funny because it does sound like something oliver would say and makes about just as much sense as olivers claims. but thats on purpose.
Pyle
4.2 / 5 (5) Oct 18, 2011
MOG is just an ad hoc modification of gravity that seems to work in some cases, but doesn't explain lensing and is incompatible with general relativity too, so Moffat's been tinkering with GR to try and make it fit. I don't think anyone really places much credence in it in the scientific community.

This is not a fair characterization of it at all.
MOG IS relativistic.
MOG has explained ALL observations it has been put up against, especially lensing and galaxy formation. Bullet Cluster et all included.

However,
MOG IS more difficult math.
MOG introduces a mysterious fifth force instead of a mysterious dark matter.
MOG hasn't offered any significant benefits over the LCDM model to sway people towards it.

Until we come up against an observation such as this study (if it sticks) that truly shows the standard LCDM model is broken, there isn't going to be any real momentum away from it.
Vendicar_Decarian
3.4 / 5 (10) Oct 18, 2011
"If stellar motions in dwarf galaxies are chaotic and in spiral galaxies the stars.. 'spiral' in towards the central black hole, ..." - Vibrating

Stars in spiral galaxies are not spiraling in toward any central black hole any more than the earth is spiraling in toward the sun.

MadLintElf
not rated yet Oct 18, 2011
Couldn't it just be that at the bottom of Super Massive Black Holes there is a 2 dimensional plane that contains the mass of all consumed?

Pyle
5 / 5 (5) Oct 18, 2011
Linty, depends on what 2 dimensions you are suggesting.

But in all likelihood, no.

Singularities are mathematical artifacts that suggest that our theories aren't perfect models of reality. There are many contexts in which infinities are used when modeling nature, but in truth NOTHING has been shown to truly be infinite. Either infinitely large or small.

BH's present an observational problem for us, but all we have to suggest true singularities are our models and math. We don't know what goes on inside the event horizon. Just a bunch of guesses. My guess is that anything involving a "singularity" is wrong.
vidyunmaya
1.2 / 5 (10) Oct 18, 2011
Sub;In-adequacy of perception
Searching minds-Guiding Spirit helps to look beyond for feasible Solutions.Keep a positive segment for growth of Scientific spirit. Cosmology vedas Interlinks help East West perception to develop vision index. Vidyardhi Nanduri
Anda
5 / 5 (3) Oct 18, 2011
Tired of your aether bible...
Vendicar_Decarian
2.3 / 5 (3) Oct 19, 2011
"Couldn't it just be that at the bottom of Super Massive Black Holes there is a 2 dimensional plane that contains the mass of all consumed?" - MadLint

To an external observer, all mass that falls toward a black hole, continually approaches but never crosses the event horizon. Hence to an outside observer a BH approaches a 2 dimensional spherical surface.
Nerdyguy
4 / 5 (5) Oct 22, 2011
Omatumr's comments are generally the longest; therefore, he knows more than the rest of you. I will now subscribe to his theories only.
Tuxford
2 / 5 (4) Oct 26, 2011
In SubQuantum Kinectics cosmology, dark matter is akin to a growing potential of the underlying etheron matrix to nucleate into matter. This is a gravity-inducing parameter. As the region reaches a critical threshold, more of the materialization potential is converted into matter itself. Such a region would likely be more uniformly distributed in similar proportion to matter contained therein, rather than separated from matter.

As the region grows into galaxies and galactic clusters, we see remaining dark matter halos surrounding the inner regions containing higher concentrations of matter. We also see regions forming Einstein rings, as this parameter is predicted to have refractive qualities.

While this is still a speculative aspect of the model in the absence of more data, it offers a potential insight into why the missing 'particle' may be so hard to find. Dark matter may be a growing etheric materialization potential expressing itself through gravitational influence.