Hubble survey carries out a dark matter census

October 13, 2011
This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MACS J1206. Galaxy clusters like these have enormous mass, and their gravity is powerful enough to visibly bend the path of light, somewhat like a magnifying glass. These so-called lensing clusters are useful tools for studying very distant objects, because this lens-like behaviour amplifies the light from faraway galaxies in the background. They also contribute to a range of topics in cosmology, as the precise nature of the lensed images encapsulates information about the properties of spacetime and the expansion of the cosmos. This is one of 25 clusters being studied as part of the CLASH (Cluster Lensing and Supernova survey with Hubble) programme, a major project to build a library of scientific data on lensing clusters. Credit: Image courtesy of NASA, ESA, M. Postman (STScI) and the CLASH Team

( -- The NASA/ESA Hubble Space Telescope has been used to make an image of galaxy cluster MACS J1206.2-0847. The apparently distorted shapes of distant galaxies in the background is caused by an invisible substance called dark matter, whose gravity bends and distorts their light rays. MACS 1206 has been observed as part of a new survey of galaxy clusters using Hubble.

Cluster MACS J1206.2-0847 (or MACS 1206 for short) is one of the first targets in a Hubble survey that will allow astronomers to construct the highly detailed dark matter maps of more galaxy clusters than ever before. These maps are being used to test previous but surprising results that suggest that dark matter is more densely packed inside clusters than some models predict. This might mean that galaxy cluster assembly began earlier than commonly thought.

The Cluster Lensing And Supernova survey with Hubble (CLASH) probes, with unparalleled precision, the distribution of dark matter in 25 massive clusters of galaxies. So far, the CLASH team has observed six of the 25 clusters.

Dark matter makes up the bulk of the Universe's mass, yet it can only be detected by measuring how its gravity tugs on visible matter and warps the fabric of space-time like a fairground mirror so that the light from distant objects is distorted.

Galaxy clusters like MACS 1206 are perfect laboratories for studying dark matter's because they are the most massive structures in the Universe to be held together by gravity. Because of their immense , the clusters act like giant cosmic lenses, amplifying, distorting and bending any light that passes through them -- an effect known as gravitational lensing.

This video zooms in on galaxy cluster MACS J1206.2-0847 (or MACS 1206 for short). The cluster has been observed by Hubble as part of CLASH (Cluster Lensing and Supernova survey with Hubble), a major programme to observe galaxy clusters whose gravity bends and distorts light passing through them. Credit: NASA, ESA, Digitzed Sky Survey 2, M. Postman (STScI) and the CLASH Survey Team. Music: John Dyson (from the album Moonwind)

Lensing effects can also produce multiple images of the same , as is evident in this Hubble picture. In particular, the apparent numbers and shapes of the distant galaxies far beyond a become distorted as the light passes through, yielding a visible measurement of how much mass there is in the intervening cluster, and how it is distributed. The substantial lensing distortions seen are proof that the dominant mass component of the clusters is dark matter. The distortions would be far weaker if the clusters' gravity came only from .

MACS 1206 lies four billion light-years from Earth. Hubble's keen vision helped CLASH astronomers to uncover 47 multiple images of 12 newly identified faraway galaxies. Finding so many multiple images in a cluster is a unique capability of Hubble, and the CLASH survey is optimised to find them. The new observations build on earlier work by Hubble and ground-based telescopes.

Among the observations which complement Hubble's is a major project using the European Southern Observatory's Very Large Telescope. Unlike Hubble, which is making images of the clusters, the VLT is carrying out spectroscopic observations, where instruments split up the galaxies' light into their component colours letting the scientists draw inferences about many of the properties of the cluster galaxies, including their distance and chemical makeup.

Taking advantage of two of Hubble's powerful cameras, the Advanced Camera for Surveys and the Wide Field Camera 3, the CLASH survey covers a broad wavelength range, from ultraviolet to near-infrared.

Astronomers need the diverse colours to estimate the distances to the lensed galaxies and to study them in more detail. Hubble's unique capabilities allow astronomers to estimate distances to galaxies that are four times fainter than those that ground-based telescopes can see.

The era when the first clusters formed is not precisely known, but is estimated to be at least nine billion years ago and possibly as far back as twelve billion years ago. If most of the clusters in the CLASH survey are found to have excessively high accumulations of in their central cores, then it may yield new clues about the early stages of the origin of structure in the Universe.

Future telescopes like the /ESA/CSA James Webb Space Telescope (JWST), a space-based infrared observatory now being built, will be able to study the fainter lensed galaxies in clusters like MACS 1206 in greater detail. JWST will be powerful enough to observe the spectra of some of the magnified and study their early chemical composition.

Explore further: Detailed dark matter map yields clues to galaxy cluster growth

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1.2 / 5 (9) Oct 13, 2011
Thanks for the story.

It would be helpful to have a clear explanation of differences between "dark matter" and compressed nuclear matter that is commonly identified as "black holes" or "neutron stars."

Thanks for your assistance.

With kind regards,
Oliver K. Manuel

5 / 5 (5) Oct 13, 2011
It would be helpful to have a clear explanation of differences between "dark matter" and compressed nuclear matter that is commonly identified as "black holes" or "neutron stars."
Wow, a reasonable question for once (though we all know what's behind it...)

Here's the main _observational_ difference: compact massive objects are not really dark, because they tend to accrete nearby matter, and the high-energy emissions from those accretion disks (and the accompanying polar jets) are very easily detected. For neutron stars, accreting matter impacting on the star's surface at relativistic velocities, makes the star shine very brightly indeed.

The main _theoretical_ difference is that dark matter haloes extend far beyond the visible outskirts of galaxies. Compact massive objects would be expected to migrate toward galactic cores (flinging ordinary matter outward in the process), rather than to hang out on the periphery in a highly uniform, sparse distribution.
2 / 5 (4) Oct 13, 2011
"They also contribute to a range of topics in cosmology, as the precise nature of the lensed images encapsulates information about the properties of spacetime and the expansion of the cosmos."
Ah come on. Precise? How can anything that is hypothesized be called precise?
4 / 5 (4) Oct 13, 2011
Precise? How can anything that is hypothesized be called precise?
The *images* are not hypothesized. Reading can be HARD...
4 / 5 (4) Oct 14, 2011
The key item for you Oliver is that you have made it quite clear that you think there is something you call neutron repulsion and it stops the formation of Black Holes. Now you ask what is the difference between a black hole and a neutron star? You claimed to know the one can't form and the other can and you never knew the difference?

Well that explains a lot of things. Like you not knowing that if Black Holes are stopped by NR then Neutron stars couldn't exist either. Of course there are all those claims that NR is causing galaxies to fragment and you spammed the site with that dozens of times.

Now to point out another thing about Neutron Repulsion as you have described it. If it has the range to fragment galaxies and the strength and range to block the formation of ANY black holes then it not only is strong enough to stop the formation of neutron stars but also ANYTHING that is held together by gravity.>>
3.7 / 5 (3) Oct 14, 2011
That is an inevitable consequence of what you have claimed. For NR to stop the formation of Black Holes and cause the fragmentation of galaxies then it is stronger than gravity at both the range of a dozen kilometers and at kiloparsecs. Which means that not only does it shatter galaxies but they could not form in first place. Planets could not form. Oliver can not exist because even Oliver lives on a planet and ALL gravity bound objects would be sundered by this hypothetical galaxy busting force.

Now will you address this issue. Or will you continue to evade it.

1 / 5 (4) Oct 15, 2011
PinkElephant and Ethelred

1. Over fifty years ago President Dwight D. Eisenhower solemnly warned of the danger to our democracy if a "scientific-technological elite" ever took control [Farewell address (17 Jan 1961)]

Document: http://mcadams.po.../ike.htm

2. Last week an editorial in Nature confirmed the danger of using consensus models as scientific facts [Nature 5, 7 (5 Oct 2011)]


3. Forty years (1971-2001) of lock-step, consensus models have damaged:

a.) The vitality of government science,
b.) The integrity of government science,
c.) Sexism and racism in government science, and
c.) The fragile self-governance we inherited in 1776!



Oliver K. Manuel
3 / 5 (2) Oct 15, 2011
So then, you can't answer the question.

I am so glad that is all cleared. Now we are quite clear on the fact that you don't a clue on how bad your theory. Not surprising since ELSEWHERE you have said you aren't a good at theory.

Yet here you are insisting you inadequate disproved theory must be the right one and all the people that are good at theory are all wrong. And yes it is disproved. My question that you refuse to even acknowledge shows with extreme clarity that you are wrong.

c.) Sexism and racism in government science, and
True Oliver is not a sexist. He abuses people of any sex.

For decades Oliver has tried to prop up a theory by attacking all opponents in highly personal ways. He attacks me by claiming I am a paid part of a vast conspiracy against him.

Answer the questions or admit you are wrong. If you were right you could answer.

2. Last week an editorial in Nature
That is not an editorial. It does not support Cranking.


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