Image of the Day: Dark Matter Filaments That Connect Galaxies in 3D for 1st Time
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October 16, 2012

Image of the Day: Dark Matter Filaments That Connect Galaxies in 3D for 1st Time

 

            Heic1215a

 

Astronomers using the NASA/ESA Hubble Space Telescope have studied a giant filament of dark matter in 3D for the first time. Extending 60 million light-years from one of the most massive galaxy clusters known, the filament is part of the cosmic web that constitutes the large-scale structure of the Universe, and is a leftover of the very first moments after the Big Bang. If the high mass measured for the filament is representative of the rest of the Universe, then these structures may contain more than half of all the mass in the Universe.

The theory of the Big Bang predicts that variations in the density of matter in the very first moments of the Universe led the bulk of the matter in the cosmos to condense into a web of tangled filaments. This view is supported by computer simulations of cosmic evolution, which suggest that the Universe is structured like a web, with long filaments that connect to each other at the locations of massive galaxy clusters. However, these filaments, although vast, are made mainly of dark matter, which is incredibly difficult to observe.

The first convincing identification of a section of one of these filaments was made earlier this year. Now a team of astronomers has gone further by probing a filament’s structure in three dimensions. Seeing a filament in 3D eliminates many of the pitfalls that come from studying the flat image of such a structure.

 Filaments of the cosmic web are hugely extended and very diffuse, which makes them extremely difficult to detect, let alone study in 3D,” says Mathilde Jauzac (LAM, France and University of KwaZulu-Natal, South Africa), lead author of the study.

The team combined high resolution images of the region around the massive galaxy cluster MACS J0717.5+3745 (or MACS J0717 for short), taken using Hubble, NAOJ’s Subaru Telescope and the Canada-France-Hawaii Telescope, with spectroscopic data on the galaxies within it from the WM Keck Observatory and the Gemini Observatory. Analysing these observations together gives a complete view of the shape of the filament as it extends out from the galaxy cluster almost along our line of sight.

The team’s recipe for studying the vast but diffuse filament combines several crucial ingredients: First ingredient: A promising target. Theories of cosmic evolution suggest that galaxy clusters form where filaments of the cosmic web meet, with the filaments slowly funnelling matter into the clusters. “From our earlier work on MACS J0717, we knew that this cluster is actively growing, and thus a prime target for a detailed study of the cosmic web,” explains co-author Harald Ebeling (University of Hawaii at Manoa, USA), who led the team that discovered MACS J0717 almost a decade ago.

Second ingredient: Advanced gravitational lensing techniques. Albert Einstein’s famous theory of general relativity says that the path of light is bent when it passes through or near objects with a large mass. Filaments of the cosmic web are largely made up of dark matter which cannot be seen directly, but their mass is enough to bend the light and distort the images of galaxies in the background, in a process called gravitational lensing. The team has developed new tools to convert the image distortions into a mass map.

Dark matter, which makes up around three quarters of all matter in the Universe, cannot be seen directly as it does not emit or reflect any light, and can pass through other matter without friction (it is collisionless). It interacts only by gravity, and its presence must be deduced from its gravitational effects, for example its effect on the rotation rate of galaxies and its ability to deflect light according to the theory of general relativity.

Third ingredient: High resolution images. Gravitational lensing is a subtle phenomenon, and studying it needs detailed images. Hubble observations let the team study the precise deformation in the shapes of numerous lensed galaxies. This in turn reveals where the hidden dark matter filament is located. “The challenge,” explains co-author Jean-Paul Kneib (LAM, France), “was to find a model of the cluster’s shape which fitted all the lensing features that we observed.”

Finally: Measurements of distances and motions. Hubble’s observations of the cluster give the best two-dimensional map yet of a filament, but to see its shape in 3D required additional observations. Colour images, as well as galaxy velocities measured with spectrometers, using data from the Subaru, CFHT, WM Keck, and Gemini North telescopes (all on Mauna Kea, Hawaii), allowed the team to locate thousands of galaxies within the filament and to detect the motions of many of them.

A model that combined positional and velocity information for all these galaxies was constructed and this then revealed the 3D shape and orientation of the filamentary structure. As a result, the team was able to measure the true properties of this elusive filamentary structure without the uncertainties and biases that come from projecting the structure onto two dimensions, as is common in such analyses.

The results obtained push the limits of predictions made by theoretical work and numerical simulations of the cosmic web. With a length of at least 60 million light-years, the MACS J0717 filament is extreme even on astronomical scales. And if its mass content as measured by the team can be taken to be representative of filaments near giant clusters, then these diffuse links between the nodes of the cosmic web may contain even more mass (in the form of dark matter) than theorists predicted. So much that more than half of all the mass in the Universe may be hidden in these structures.

The forthcoming NASA/ESA/CSA James Webb Space Telescope, scheduled for launch in 2018, will be a powerful tool for detecting filaments in the cosmic web, thanks to its greatly increased sensitivity.

The international team of astronomers in this study consists of Mathilde Jauzac (Laboratoire d’Astrophysique de Marseille, France, and University of KwaZulu-Natal, South Africa), Eric Jullo (Laboratoire d’Astrophysique de Marseille, France and Jet Propulsion Laboratory, USA), Jean-Paul Kneib (Laboratoire d’Astrophysique de Marseille), Harald Ebeling (University of Hawaii, USA), Alexie Leauthaud (University of Tokyo, Japan), Cheng-Jiun Ma (University of Hawaii), Marceau Limousin (Laboratoire d’Astrophysique de Marseille and University of Copenhagen, Denmark), Richard Massey (Durham University, UK) and Johan Richard (Lyon Observatory, France).

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Comments

Contrary to what science still believes, at the time of the Big Bang there were no atoms but only waves carrying energy through the infinite Void.
If we could view the Universe from outside, It would look like an egg-shaped cloud with winds running in perpetual motion inside of It.
The energy is like those winds running at maximum speed and pushing out the borders of the Universe.

The Universe continues to expand as the waves that travel at the border of the Universe have never encountered, nor will ever encounter, any interference from the Void. These waves will forever expand the Space of the Universe they create and leave behind.

Wave-behavior relates to the medium in which the waves travel.
Thus, wave-behavior at the border of the Universe is different than wave-behavior within the Universe.

Inside the Universe, waves change their frequencies by colliding with other energy during their travel. These waves, because of the encountered interference, continue to transform part of their original energy in other forms. Waves travel gradually releasing heat, or amounts of energy, and their original short wavelengths, in time become longer and longer as they carry less and less energy than they did when they first started to travel. These waves lose energy releasing it in form of other waves with wavelengths longer than their own.

For example, the gamma rays, over time, diminish their energy level (and their frequency) to become X rays, from X rays they will become ultraviolet and so on. The original quantum is not lost but distributed into other forms of energy through "spontaneous symmetry breaking".

Once reached an almost flat longitude (and lower critical energy level) these waves solidify into hydrogen atoms breaking up their energy in opposite elements, like the split ends of a broken hair.
When the hydrogen atoms are reached by the heat of other incoming waves they fuse together to create more complex forms of energy.

http://www.wikinfo.org/Multilingual/index.php/Wavevolution

@wavettore: when you say "Contrary to what science still believes ..." you actually create a contradiction. Science is not about believing, it is about separating facts and conclusions from belief.

Is your hypothesis based on facts and observations, or are you just gambling around with some math?

The big bang would have created energy, which can convert to matter spontaneously.
The overriding principle of science is "the simplest solution is most likely correct".
It has seemed evident to me that the formation of a black hole would create an isolated "universe" that is free to grow as it acretes energy(matter) from outside. And it is only isolated in so far as we cannot "see" inside it.
If two quantum entangled particle diverge, and only one is consumed by the black hole, would we not have an information gateway of one "bit" across the event horizon?
Sorry I got way off topic. I have ADHD as an excuse :)

You skipped a few steps from energy condensing into H atoms but I can see your point in eventuality. You forgot stuff or steps that energy can condense into FIRST that combined makes up quarks, then quarks,then protons, electrons etc.. "Once reached an almost flat longitude (and lower critical energy level) these waves solidify into hydrogen atoms breaking up their energy in opposite elements". Yes, energy condensed into, eventually, mass from the battle of matter vs antimatter in the first steps of making a universe, in proportion to E=mc2 in reverse. We think of Einsteins formula as how much energy we can get out of mass but in this case, think in reverse, how much mass can we get out of X amount of energy?

Nice article. So half the universe is dark matter? I just read where 20% of it is dark matter and yet another article said about 80% is dark matter. The difference between real news and a rag tabloid is the difference in opinion of dark matter vs regular matter. Someone is literally starving for news, grabbing any comment or postulate (I can't call them theories for theories require real proof) to publish (or to keep sucking up generous grants for so called research). It's like the Popular Science section, "I'd like to see them make..." aka pure fantasy. Then come the really ignoramouses without the slightest inkling of education who say, Oh it's so simple, dah... the great one done it. I get more out of Peanuts comic strips than this drivel.


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