Cosmic Noise

Hubble Provides Most Detailed Dark Matter Map Yet

Article Updated: 24 Dec , 2015

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Using Hubble’s Advanced Camera for Surveys, astronomers have been able to chart invisible dark matter in a distant galaxy, which enabled them to create one of the sharpest and most detailed maps of dark matter in the universe. Looking for invisible and indeterminate matter is a difficult job, but one that astronomers have been trying to do for over a decade. This new map also might provide clues on that other mysterious stuff in the universe — dark energy – and what role it played in the universe’s early formative years.

A team led by Dan Coe at JPL used Hubble to look at Abell 1689, located 2.2 billion light-years away. The cluster’s gravity, which mostly 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, making the galaxies look distorted and fuzzy. 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.

What they found suggests that galaxy clusters may have formed earlier than expected, before the push of dark energy inhibited their growth.

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.

“The lensed images are like a big puzzle,” Coe said. “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.

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 computer simulations 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 said. “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.”

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 dark matter distributions and look for more conclusive evidence of early cluster formation, and possibly early dark energy.

For more information see the HubbleSite.

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Herkfixer
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Herkfixer
November 11, 2010 1:38 PM

Due to the large concentration in the center, this looks like a great confirmation of the “Great Attractor” theory for our own cluster. Maybe like super-massive black holes are a normality for the center of galaxies, this super-massive dark matter center could be some part of a greater explanation of how galaxy clusters form.

Lawrence B. Crowell
Member
Lawrence B. Crowell
November 11, 2010 3:11 PM

Dark energy began to dominate the universe about 4 billion years ago, or around the time the solar system formed. Before then the universe was matter dominated, so galaxy clusters had plenty of time to coalesce. Galaxy dynamics maven can then compute the upper bound on galaxy cluster mass given a 9 billion year time frame.

This image is a keeper.

LC

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
November 11, 2010 11:15 PM

So the Flying Spaghetti Monster is real!?

It stands to reason that DM influenced the visible universe more than we earlier accounted for. But since the old cosmology made local sense DM’s influence must be stealthed analogous to the fashion seen here.

Lawrence B. Crowell
Member
Lawrence B. Crowell
November 12, 2010 7:03 AM
While this is long, it pretty much covers the basic stuff — this is not my personal theory, but is based on standard concepts of cosmology. The FLRW cosmology is comparatively simple to understand. The motion of the space is given by a scale factor which evolves with time. The Hamiltonian for the scale factor a in FLRW logic is (a’/a)^2 = (8pi G rho/3) – k/a^2, ( ‘ = d/dt) which has different solutions for different densities rho. This leads to a dynamical equation of motion when considered as a Hamiltonian d^2a/dt^2 = (8pi G?/3)a – k/a^2. For a constant density rho = /\/(8pi G) for /\ = “Lambda” the cosmological constant. This solution for k =… Read more »
Question
Member
Question
November 12, 2010 2:10 PM

strong evidence for what we like to call “dark matter”. dark matter therory un-RIP!

possible further evidence to suggest that (once again) mans’ estimate of the age of the universe is incorrect.

Question
Member
Question
November 12, 2010 2:11 PM

therory

Torbjorn Larsson OM
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Torbjorn Larsson OM
November 13, 2010 7:43 AM

Capper or madcapper? In any case, opinion doesn’t cap the facts, and the fact is that this was a *successful* test of standard cosmology – it survived!

Hannes
Member
Hannes
November 13, 2010 1:17 PM

@LBC

You are only making assumptions.

“The entropy is S ~ 4?A/L_p^2 = 12?/(?L_p^2). But if k = +1 it is clear the solution is different, but only early on. The observed universe is k = 0, which is spatially flat with curvature in the “time direction,” and this describes the inflationary period of the universe.”

Please tell me first what entropy really means, I see no insight here. Do not feel offended personally btw. Nobody actually knows what entropy means.

Astrofiend
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Astrofiend
November 13, 2010 2:33 PM

“Nobody actually knows what entropy means.”

What do you mean? Maybe nobody knows what it means in some sort of deep existential sense, such as ‘nobody knows what quantum mechanics really means’, but just like QM the concept of entropy is clearly defined, as is the mathematical framework in which it appears. What are you trying to say?

Lawrence B. Crowell
Member
Lawrence B. Crowell
November 13, 2010 5:20 PM

Hannes: the formula for entropy can be derived, but is a bit complicated to work through. Entropy is well enough defined, and has a number of different forms. In statistical mechanics it is the number of ways microstates may be rearranged without changing a macrostate. The entropy is then measured by the size of this macrostate V, as S = -k log(V). In information theory for a set of bits with probability P_i so S = -k sum_i P_i log(P_i). For these probabilities corresponding to entangled states there is a corresponding entanglement entropy — in a bipartite Q-bit form. Things get really fun in a multi-partite form.

LC

jimhenson
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jimhenson
November 14, 2010 6:39 AM
why should somebody be happy if dark matter was conclusively disproved?? EM forces can explain dark matter and black holes in the plasma labs. ARP’S 2003 quasar catalogue shows many photos of luminous filaments connecting quasars with a nearby host galaxy. All quasars except one disc are near a galaxy, and are believed to form by galaxy collisions mergers. Arp says they are ejected at higher redshifts, and are intrinsic redshifts that falsify the big-bang model of dark energy expansion. Just recently the first reverse gravitational lens was discovered, where a foreground quasar only 1.6 billion light years away supposedly lenses a galaxy 7 billion light years behind it. the photo only reveals a bright flash behind the… Read more »
Question
Member
Question
November 14, 2010 12:43 AM
[i] “Capper or madcapper? In any case, opinion doesn’t cap the facts, and the fact is that this was a *successful* test of standard cosmology – it survived!” [/i] ////////////////// There don’t seem to be any caps in modern cosmology. Anything goes! Nevertheless, I’m glad that “standard” cosmology survived this (previously unknown by me) threat to its existence. I’m actually not opposed to dark matter theory, I simply have issues with the seemingly 100% conclusiveness with which it has often been presented in the last several years. Is it likely? Maybe. Has enough evidence of its existence been shown to me that I can now assume with almost absolute certainty that dark matter is there and never question… Read more »
Lawrence B. Crowell
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Lawrence B. Crowell
November 14, 2010 6:40 AM
The dark matter issue does come from the anomalous motion of stars in the galaxy. It is not hard to show with the Poisson equation &_i&^i? = 4?G rho, &_i = 3 dimensional directional derivative, that for a region of constant density rho an integration over a volume is constant on the right hand side. One the left hand side one can use Stokes rule to get (&_iU)*A = 4?G rho V for A the area bounding the volume V, and U is the potential function of gravity. For A = 4?r^2 and the volume V = 4?r^3/3 you get the force F = &^iU ~ constant*r. So this is a spring force and gives dynamics similar to… Read more »
Torbjorn Larsson OM
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Torbjorn Larsson OM
November 14, 2010 9:53 AM
@ Hannes: Nobody actually knows what entropy means. Of course we know, or we wouldn’t be able to use it. LC gave the most fundamental definition, which the classical definition builds on in an effective (i.e useful in theory but not fundamental) form. More broader, these aren’t assumptions but testable hypotheses. For example inflation is tested as part of standard cosmology. (Though direct tests still fall just shy of 3 sigma. Wait for Planck!) The same goes for DM. @ Capper: Anything goes! That you claim so, right after I stated the relevant facts, means there is no basis for a rational discussion. It as inane as rejecting gravity. I can only recommend that you try to learn… Read more »
jimhenson
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jimhenson
November 14, 2010 6:46 PM

increased order is lower entropy, and higher entropy is increased randomness or disorder. if you heat ice crystals or boil water, they gain entrophy becoming gas particles that have less order and more chances for random collisions, then when held in a crystalline form or liquid state.
@ nobody actually knows what the universe is or means, perhaps it is a collective theory

The Eclectic Exterminator of Stupid Electricians
Member
The Eclectic Exterminator of Stupid Electricians
November 14, 2010 7:47 PM

“Nobody actually knows what entropy means.”

Anyone reading the progression of deterioration comments here will see entropy in action!

Not one person here has commented on the “strong X-ray emission” (observations) of the selected CLASH clusters that might be suppressing the “growth of all galaxy clusters” (the theory.) This rest of the comments are frankly just the usual irrelevant claptrap — avoiding the story completely. Frankly, Nancy should be deleting most of them as just “personal theory.”

Lawrence B. Crowell
Member
Lawrence B. Crowell
November 15, 2010 5:41 AM
Hon. Salacious B. Crumb: I wrote the expository above due to the usual confusion over dark matter and dark energy, and problems people have with cosmology. What I wrote is basically the standard model, and is not my personal theory. I also repost my argument for dark matter above, which is based on textbook standard Newtonian gravity. I wrote this with unicode symbols that I did not change here and they showed up as ? marks. The dark matter issue does come from the anomalous motion of stars in the galaxy. It is not hard to show with the Poisson equation &_i&^iU = 4pi G rho, &_i = 3 dimensional directional derivative, U the gravitational potential, and for… Read more »
Hannes
Member
Hannes
November 15, 2010 12:41 PM

John von Neumann: “…nobody knows what entropy really is”

–Conversation between Claude Shannon and John von Neumann regarding what name to give to the “measure of uncertainty” or attenuation in phone-line signals (1949)

We don’t know if a blackhole [if it exists] has the maximum allowed entropy.

Other option: look at the no-hair theorem, there is zero entropy. But 2nd law of thermodynamics problem in that case.

Question
Member
Question
November 15, 2010 1:44 PM
Larsson: “That you claim so, right after I stated the relevant facts, means there is no basis for a rational discussion. It as inane as rejecting gravity. I can only recommend that you try to learn something about science if you are able…” ///////////////////////// Above is the type of comment made by a frustrated person. What’s worse is that you didn’t even address what I was writing about. If you are not prepared to deal with questions in earnest, why bother trolling? Here are your “facts” from this thread (unless there is some mysterious missing post): First comment: “So the Flying Spaghetti Monster is real!? It stands to reason that DM influenced the visible universe more than we… Read more »
The Eclectic Exterminator of Stupid Electricians
Member
The Eclectic Exterminator of Stupid Electricians
November 15, 2010 5:17 PM

Capper
Your out of you depth, sonny. Entropy, and what you are rabbiting on about) is totally irrelevant to this article. End of story.

Hannes (obviously related to the PC/EU nutter, after their messiah, Hannes Alfvin) is likely just an Anaconda clone. Again, entropy has nothing to do with this story.I’d take no notice of such jackasses.

As for LBC’s comments, I just accept them as they are written.

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