Detailed dark matter map yields clues to galaxy cluster growth

Nov 12, 2010
This is one of the most detailed maps of dark matter in our universe ever created. The location of the dark matter (tinted blue) was inferred through observations of magnified and distorted distant galaxies seen in this picture. Image credit: NASA/JPL-Caltech/ESA/Institute of Astrophysics of Andalusia, University of Basque Country/JHU

(PhysOrg.com) -- Astronomers using NASA's Hubble Space Telescope took advantage of a giant cosmic magnifying glass to create one of the sharpest and most detailed maps of dark matter in the universe. Dark matter is an invisible and unknown substance that makes up the bulk of the universe's mass.

The new dark matter observations may yield new insights into the role of in the universe's early formative years. The result suggests that may have formed earlier than expected, before the push of dark energy inhibited their growth. A mysterious property of space, dark energy fights against the of dark matter. Dark energy pushes galaxies apart from one another by stretching the space between them, thereby suppressing the formation of giant structures called galaxy clusters. One way astronomers can probe this primeval tug-of-war is through mapping the distribution of dark matter in clusters.

A team led by Dan Coe at NASA's Jet Propulsion Laboratory in Pasadena, Calif., used Hubble's Advanced Camera for Surveys to chart the invisible matter in the massive galaxy cluster Abell 1689, located 2.2 billion light-years away. The cluster's gravity, the majority of which comes from dark matter, acts like a cosmic magnifying glass, bending and amplifying the light from distant galaxies behind it. This effect, called gravitational lensing, produces multiple, warped, and greatly magnified images of those galaxies, like the view in a funhouse mirror. By studying the distorted images, astronomers estimated the amount of dark matter within the cluster. If the cluster's gravity only came from the visible galaxies, the lensing distortions would be much weaker.

Based on their higher-resolution mass map, Coe and his collaborators confirm previous results showing that the core of Abell 1689 is much denser in dark matter than expected for a cluster of its size, based on of structure growth. Abell 1689 joins a handful of other well-studied clusters found to have similarly dense cores. The finding is surprising, because the push of dark energy early in the universe's history would have stunted the growth of all galaxy clusters.

"Galaxy clusters, therefore, would had to have started forming billions of years earlier in order to build up to the numbers we see today," Coe explains. "At earlier times, the universe was smaller and more densely packed with dark matter. Abell 1689 appears to have been well fed at birth by the dense matter surrounding it in the early universe. The cluster has carried this bulk with it through its adult life to appear as we observe it today."

Mapping the Invisible

Abell 1689 is among the most powerful gravitational lensing clusters ever observed. Coe's observations, combined with previous studies, yielded 135 multiple images of 42 background galaxies.

"The lensed images are like a big puzzle," Coe says. "Here we have figured out, for the first time, a way to arrange the mass of Abell 1689 such that it lenses all of these background galaxies to their observed positions." Coe used this information to produce a higher-resolution map of the cluster's dark matter distribution than was possible before.

Coe teamed with mathematician Edward Fuselier, who, at the time, was at the United States Military Academy at West Point, to devise a new technique to calculate the new map. "Thanks, in large part, to Eddie's contributions, we have finally `cracked the code' of . Other methods are based on making a series of guesses as to what the mass map is, and then astronomers find the one that best fits the data. Using our method, we can obtain, directly from the data, a mass map that gives a perfect fit."

Astronomers are planning to study more clusters to confirm the possible influence of dark energy. A major Hubble program that will analyze dark matter in gigantic galaxy clusters is the Cluster Lensing and Supernova survey with Hubble (CLASH). In this survey, the telescope will study 25 clusters for a total of one month over the next three years. The CLASH clusters were selected because of their strong X-ray emission, indicating they contain large quantities of hot gas. This abundance means the clusters are extremely massive. By observing these clusters, astronomers will map the distributions and look for more conclusive evidence of early cluster formation, and possibly early dark energy.

Explore further: The entropy of black holes

Related Stories

A cluster and a sea of galaxies (w/ Video)

May 05, 2010

(PhysOrg.com) -- A new wide-field image released today by ESO displays many thousands of distant galaxies, and more particularly a large group belonging to the massive galaxy cluster known as Abell 315. As ...

Cluster collisions switch on radio halos

Aug 30, 2010

(PhysOrg.com) -- This is a composite image of the northern part of the galaxy cluster Abell 1758, located about 3.2 billion light years from Earth, showing the effects of a collision between two smaller galaxy ...

Recommended for you

The entropy of black holes

Sep 12, 2014

Yesterday I talked about black hole thermodynamics, specifically how you can write the laws of thermodynamics as laws about black holes. Central to the idea of thermodynamics is the property of entropy, which c ...

Modified theory of dark matter

Sep 12, 2014

Dark matter is an aspect of the universe we still don't fully understand. We have lots of evidence pointing to its existence (as I outlined in a series of posts a while back), and the best evidence we have point ...

Gaia discovers its first supernova

Sep 12, 2014

(Phys.org) —While scanning the sky to measure the positions and movements of stars in our Galaxy, Gaia has discovered its first stellar explosion in another galaxy far, far away.

Astronomers unveil secrets of giant elliptical galaxies

Sep 12, 2014

New findings of how giant elliptical galaxies move have been discovered by an international team of astronomers using the newly installed Multi Unit Spectroscopic Explorer (MUSE) at the European Southern Observatory's (ESO) ...

User comments : 31

Adjust slider to filter visible comments by rank

Display comments: newest first

TimESimmons
1 / 5 (5) Nov 12, 2010
Abell 1689 included in the evidence here:-

http://www.presto...ndex.htm
Parsec
4.8 / 5 (8) Nov 12, 2010
Abell 1689 included in the evidence here:-

http://www.presto...ndex.htm

Inventing entirely new physics or religions to explain observations is as old as mankind. It might even be older than that...

However, The principle of Occam's Razor suggests that the simplest explanations are usually correct. While its true that various anti-gravity theories COULD be correct, its much simpler to explain dark matter as one of the number of possible stable particles with mass that don't interact with light.
Pyle
4.3 / 5 (3) Nov 12, 2010
its much simpler to explain dark matter as one of the number of possible stable particles with mass that don't interact with light.

What? Simpler? No, the "possible stable particles with mass" you mention aren't really any simpler than the AGM alternatives.

I think a better response to Tim is - thank you for sharing your ideas in a concise way. We look forward to seeing publication of peer reviewed research demonstrating the predictive ability of your theories.

Commenters on this website throw out that hygiene tool WAY too frequently.
Parsec
5 / 5 (4) Nov 12, 2010
its much simpler to explain dark matter as one of the number of possible stable particles with mass that don't interact with light.

What? Simpler? No, the "possible stable particles with mass" you mention aren't really any simpler than the AGM alternatives.

Commenters on this website throw out that hygiene tool WAY too frequently.


Its a matter of opinion I suppose. I personally think that any one of the stable particles that are predicted with very simple extensions to the SM are preferable to creating a new particle that emits repulsive gravitons. Anti-gravity requires entirely new physics to explain.
theon
1 / 5 (3) Nov 12, 2010
Confirming existing conclusions (which ones?), mentioning no scientific paper. How far must we sink further, has science become synonymous to hyping? Will that solve any problem?
theon
1 / 5 (1) Nov 12, 2010
its much simpler to explain dark matter as one of the number of possible stable particles with mass that don't interact with light.

Europhysics Letters 86 (2009) 59001 attributes dark matter in this cluster to neutrinos with mass of 1.5 eV.
Au-Pu
2.3 / 5 (3) Nov 12, 2010
This article says and I quote
"Dark matter is an invisible and ....."
"The new dark matter observations may...."
????????
Ravenrant
3 / 5 (6) Nov 12, 2010
The whole premise of this article and others like it is unsupported by the very statements in it.

"... to create one of the sharpest and most detailed maps of dark matter in the universe. Dark matter is an invisible and unknown substance ...."

Those two sentences contradict each other. They are mapping an effect, the cause of which is unknown. Dark matter is a theory to explain the effect. They are NOT mapping dark matter until we know what it is or if it even exists.
thales
4 / 5 (7) Nov 12, 2010
This article says and I quote
"Dark matter is an invisible and ....."
"The new dark matter observations may...."
????????


One may indirectly observe something by observing its effects.
Slotin
1 / 5 (6) Nov 12, 2010
The principle of Occam's Razor suggests that the simplest explanations are usually correct.
The question is, what the "simplest explanation" means. Is the explanation of lightning as a "messenger of God" simple enough?

A. Einstein: "Make everything as simple as possible, but not simpler"

The simplicity therefore cannot serve as an ultimate criterion of general truth. Many modern theories are actually quite abstract and complex.

The assumption, cosmic space is filled with sparse antimatter looks like unnecessary complication - but it explains, where the missing antimatter disappeared after Big Bang (between other). It explains, why we are observing 511 keV signal in contact of observable matter with dark matter. Many astronomers are believing by now, it's because dark matter particles decays into antimatter - but what if dark matter contain antimatter directly?

Why this simple assumption wasn't considered from its very beginning?
tkjtkj
4.5 / 5 (6) Nov 12, 2010

One may indirectly observe something by observing its effects.


yes, exactly... as the 'planet searchers' have shown on a cosmic scale ..
Is it now every few days that a planet is newly discovered by a 'wobble'?
Decimatus
1 / 5 (4) Nov 12, 2010
Personally I think the best Occam's Razor explanation for "Dark energy" would be to simply say that space isn't expanding, light just looses energy after spending billions of years flying through the gravity wells of countless stars and galaxies.

If you take the viewpoint that light looses energy/redshifts as it leaves a star, then you must also factor in that it is loosing a small amount of energy/redshifting every second that it exists as the giant gravity wells coming from galaxies and galactic clusters will always be playing on it.

So, for me, light that comes from a billion light years away is simply more redshifted because it is a billion years old and gravity has been riding on it's back the whole time.

This isn't to say that the universe isn't expanding, maybe it is, but I don't think it is doing the redshifting.
PS3
1 / 5 (1) Nov 12, 2010
couldn't dm be neutrinos since they are also hard to detect?
DamienS
3.4 / 5 (5) Nov 12, 2010
Personally I think the best Occam's Razor explanation for "Dark energy" would be to simply say that space isn't expanding, light just looses energy

Tired light theory and its proponents are almost as tiring as the aether and EU nutjobs.
Decimatus
1 / 5 (6) Nov 12, 2010
Personally I think the best Occam's Razor explanation for "Dark energy" would be to simply say that space isn't expanding, light just looses energy

Tired light theory and its proponents are almost as tiring as the aether and EU nutjobs.


Aether as in Dark Matter and all the crap they say exists but which has never even been seen or touched?

I can at least prove that lights looses energy in a gravity well. Can you do the same for dark energy? No.
DamienS
3.7 / 5 (6) Nov 12, 2010
I can at least prove that lights looses energy in a gravity well. Can you do the same for dark energy?

It may have escaped your attention, but this article is primarily about dark matter. That gravitational lensing occurs to the extent that it does (where there's insufficient luminous matter) is pretty strong evidence for dark matter. Galaxy rotation curves is another. Whereas tired light has been categorically debunked.
Decimatus
1 / 5 (6) Nov 13, 2010
I can at least prove that lights looses energy in a gravity well. Can you do the same for dark energy?

It may have escaped your attention, but this article is primarily about dark matter. That gravitational lensing occurs to the extent that it does (where there's insufficient luminous matter) is pretty strong evidence for dark matter. Galaxy rotation curves is another. Whereas tired light has been categorically debunked.


It may have escaped your attention, but the same guys who claim that dark energy is pushing galaxies apart also needed dark matter for their equations to match up.

Lets just make some crap up to fit our math that obviously doesn't match reality.
Decimatus
1 / 5 (4) Nov 13, 2010
Double Post.
Ravenrant
3.5 / 5 (4) Nov 13, 2010
This article says and I quote
"Dark matter is an invisible and ....."
"The new dark matter observations may...."
????????


One may indirectly observe something by observing its effects.


Yes, but you can't say what it is when you don't KNOW what it is.

This article should say: "We are mapping gravitational effects that aren't explained by current theories and postulating the existence of dark matter to explain it. Dark matter may or may not cause this because current accepted theories not only don't explain what dark matter is, they can't say it even exists."

Gravitational effects are as much evidence of the existence of dark matter as cattle mutilations are evidence of Chupacabra.
DamienS
3.2 / 5 (6) Nov 13, 2010
Yes, but you can't say what it is when you don't KNOW what it is.

You can say what it is within the current broadly accepted framework. Dark matter is a placeholder name for matter which must have certain constrained characteristics - it's not a free-for-all. New observations help to place constraints on the range of dark matter candidates. So far, all the evidence points in this direction. Alternatives simply aren't compelling and aren't supported observationally. These unsupported alternatives include tired light and various MOND theories (which are at least plausible, unlike tired light). If there is a better alternative to dark matter, I'd like to hear about it (I really would).
Decimatus
1 / 5 (8) Nov 13, 2010
Yes, but you can't say what it is when you don't KNOW what it is.

You can say what it is within the current broadly accepted framework. Dark matter is a placeholder name for matter which must have certain constrained characteristics - it's not a free-for-all. New observations help to place constraints on the range of dark matter candidates. So far, all the evidence points in this direction. Alternatives simply aren't compelling and aren't supported observationally. These unsupported alternatives include tired light and various MOND theories (which are at least plausible, unlike tired light). If there is a better alternative to dark matter, I'd like to hear about it (I really would).


I guess if all we are allowed to say is what is in this list of "Broadly Accepted Framework" we don't really need to discuss or think about any of this any further.

Yep, just think what you are told to think. That is how science operates afterall.
DamienS
3 / 5 (4) Nov 13, 2010
I guess if all we are allowed to say...

Which logical fallacy is that - Appeal to Ridicule or Straw Man?
Decimatus
1.3 / 5 (7) Nov 13, 2010
I guess if all we are allowed to say...

Which logical fallacy is that - Appeal to Ridicule or Straw Man?


The logical fallacy that I am arguing with a fanatic that won't take any other possibility than that which is equated out in whatever Physics Bible he is reading.

I am not asking you to think for yourself, I am just pointing out that Dark Matter/Dark Energy isn't a fact, so you don't have to take it as such.
DamienS
3.7 / 5 (3) Nov 13, 2010
The logical fallacy that I am arguing with a fanatic that won't take any other possibility than that which is equated out in whatever Physics Bible he is reading.

You appear to be well versed in logical fallacies - you've just added Ad Hominem. I can only point out the current best fit thinking in cosmology, I cannot make you make sense of it. If you wish to cling to outdated notions, that is up to you. You certainly aren't unique in this respect on this board.
Decimatus
1.3 / 5 (4) Nov 13, 2010
You appear to be well versed in logical fallacies -


Your problem could be that you think I cling to that theory, like you seem to the "accepted" theory.

I also support several other theories as possible alternate explanations for dark matter/energy.

Such as:

-Numerous Stellar Mass Blackholes for the extra mass.
-Gravity from an extra dimension tugging on our matter.
-Gravity from the past and the future tugging on present matter(and vice versa).
-A possible plateu for gravitational scaling causing it to be greater than we are able measure at longer distances.

I don't really understand why you have a problem with alternate theories when the thousands of scientists have used the same old equations for a century and still don't really understand how the forces of nature, especially gravity, work together at fundamental levels.
DamienS
5 / 5 (2) Nov 13, 2010
I don't really understand why you have a problem with alternate theories when the thousands of scientists have used the same old equations for a century and still don't really understand how the forces of nature, especially gravity, work together at fundamental levels.

I never said I had a problem with alternate theories. What I did say was that based on all available, measurable evidence to date, the overwhelming favourite, by far, is dark matter. None of the alternatives you list stands up to scrutiny, and they have been scrutinized.
* Stellar Mass BH - not enough of them to make a dent. They would have to be in impossible distributions and there would be associated radiation emissions.
* Gravity from extra dimensions - highly speculative at best, based on no real observational evidence.
* Gravity from the past and the future tugging on present matter - even more speculative.
* A plateu for gravitational scaling - that's a MOND theory. None of them are compatible with GR.
theon
5 / 5 (1) Nov 13, 2010
Confirming existing conclusions (which ones?), mentioning no scientific paper. How far must we sink further, has science become synonymous to hyping? Will that solve any problem?

Mea culpa. The paper appeared in the Astrophysical Journal
yyz
5 / 5 (1) Nov 13, 2010
"Mea culpa. The paper appeared in the Astrophysical Journal"

A version of the ApJ paper on A1689 is available here: http://hubblesite.../pdf.pdf
Ravenrant
3.5 / 5 (2) Nov 15, 2010
This article says and I quote
"Dark matter is an invisible and ....."
"The new dark matter observations may...."
????????


One may indirectly observe something by observing its effects.


Wrong, that is only true if you know what you are observing, if you don't know what it is you are just observing the effects and guessing as to what it is that causes them. For example, the sun was observed to rise and fall every day since man first started looking and the conclusion was that it was moving while the earth stood still.
lengould100
1 / 5 (1) Nov 16, 2010
and the conclusion was that it was moving while the earth stood still.
Well Duh! How could a flat earth be moving / rotating without all the unattached bits falling off?
peter09
not rated yet Nov 20, 2010
Can anyone tell me why, if Dark Matter is gravitationally active, it does not clump and form its equivalents of of matter such as 'Dark Stars', 'Dark Black Holes', etc?