Galaxy Clusters Reveal Distribution of Dark Matter
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June 13, 2013

Galaxy Clusters Reveal Distribution of Dark Matter


            Abell2218_hst

 

“Each bright city light is a galaxy, and the dark areas between the lights that appear to be empty during the night are actually full of dark matter. You can think of the dark matter in a galaxy cluster as being the infrastructure within which the galaxies live,” say an international team of astronomers from Taiwan, UK, Japan, and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA). The researchers used a large sample of galaxy clusters to find out how the density of dark matter changes from the center of a typical galaxy cluster to its outskirts.has used the Subaru Telescope to measure the density of dark matter in fifty galaxy clusters and found that its density gradually decreases from the center of these cosmic giants to their diffuse outskirts. This new evidence about the mysterious dark matter that pervades our Universe conforms to the predictions of cold dark matter theory, known as “CDM”.

Almost all of the bright objects in the Hubble Space Telescope image above are galaxies in the cluster known as Abell 2218. The cluster is so massive and so compact that its gravity bends and focuses the light from galaxies that lie behind it. As a result, multiple images of these background galaxies are distorted into long faint arcs - a simple lensing effect analogous to viewing distant street lamps through a glass of wine. The cluster of galaxies Abell 2218 is itself about two billion light-years away in the northern constellation Draco. Three images of this young, still-maturing galaxy are faintly visible in the white contours near the image top and the lower right. The recorded light, further analyzed with a Keck Telescope, left this galaxy when the universe was only about five percent of its current age.

Few scientists seriously doubt the existence of dark matter, which researchers discovered almost eighty years ago. Nevertheless, astronomers cannot directly see dark matter in the night sky, and particle physicists have not yet identified a dark matter particle in their experiments. “What is dark matter?” is a big unanswered question facing astronomers and particle physicists, especially because invisible dark matter probably makes up 85% of the mass of the Universe.

The current team, led by ASIAA Postdoctoral Fellow Nobuhiro Okabe and Dr. Graham Smith (University of Birmingham, England), used the Subaru Prime Focus Camera (Suprime-Cam) to investigate the nature of dark matter by measuring its density in fifty galaxy clusters, the most massive objects in the Universe. “A galaxy cluster is like a huge city viewed from above during the night”, explained Smith.

“Each bright city light is a galaxy, and the dark areas between the lights that appear to be empty during the night are actually full of dark matter. You can think of the dark matter in a galaxy cluster as being the infrastructure within which the galaxies live.” The team wanted to use a large sample of galaxy clusters to find out how the density of dark matter changes from the center of a typical galaxy cluster to its outskirts.

The density of dark matter depends on the properties of the individual dark matter particles, just like the density of everyday materials depends on their components. CDM, the leading theory about dark matter to date, predicts that dark matter particles only interact with each other and with other matter via the force of gravity; they do not emit or absorb electromagnetic radiation and are difficult if not impossible to see.

The team chose to observe dark matter by using gravitational lensing, which detects its presence through its gravitational interactions with ordinary matter and radiation. According to Einstein’s theory of relativity, light from a very distant bright source bends around a massive object, e.g., a cluster of galaxies, between the source object and the observer. It follows from this principle that the dark matter in cosmic giants like galaxy clusters alters the apparent shape and position of distant galaxies. Lead author Okabe enthused, “The Subaru Telescope is a fantastic instrument for gravitational lensing measurements. It allows us to measure very precisely how the dark matter in galaxy clusters distorts light from distant galaxies and gauge tiny changes in the appearance of a huge number of faint galaxies.”

CDM theory describes how dark matter in galaxy clusters changes from its dense center to its lower density edges in two ways. One is a simple measure of the galaxy cluster’s mass, the amount of matter that it contains. The other is a concentration parameter, which is a single measurement of the cluster’s average density, how compact it is. CDM theory predicts that central regions of galaxy clusters have a low concentration parameter while individual galaxies have a high concentration parameter.

The team combined measurements from observations of fifty of the most massive known galaxy clusters to calculate their concentration parameter. They found that the density of dark matter increases from the edges to the center of the cluster, and that the concentration parameter of galaxy clusters in the near Universe aligns with CDM theory. The averaged mass map (attachment) is remarkably symmetrical with a pronounced mass peak. The mass density distribution for individual clusters shows a wide range of densities.

Past research based on a small number of clusters found that they had large concentration parameters and did not conform to CDM theory. Measurement of the average concentration parameter from a large number of clusters yielded a different result, which supports CDM theory. Okabe commented on the team’s findings, based on a larger sample of galaxy clusters: “This is a very satisfying result, which is based on a very careful analysis of the best available data”.

What does the future hold for the team’s continued research on dark matter? Smith noted, “We don’t stop here. For example, we can improve our work by measuring dark matter density on even smaller scales, right in the center of these galaxy clusters. Additional measurements on smaller scales will help us to learn more about dark matter in the future.”

The study was published online in The Astrophysical Journal Letters on May 17, 2013. The full article entitled “LoCuSS: The Mass Density Profile of Massive Galaxy Clusters at z=0.2” is available at The Astrophysical Journal Letters website at: http://iopscience.iop.org/2041-8205/769/2/L35/pdf/2041-8205_769_2_L35.pdf

The Daily Galaxy via http://www.sinica.edu.tw/

Comments

Confirm Dark Matter?

http://news.sciencemag.org/sciencenow/2013/04/two-billion-dollar-cosmic-ray-de.html?ref=em

With utmost sincere respect, dark matter and dark energy may be found only in some human minds. Energy is mass in motion; as the galaxy clusters move since inflation their mass decreases as their travel distance increases. Thus ALL mass and energy are accounted for.

Dark energy and matter YOK. They simply do not exist.
All The Mass Of The Universe Formed At The Pre-Big-Bang Singularity

The universe is a two-poles entity, an all-mass and an all-energy poles.

The elementary particle of the universe is the graviton. The gravitons are compacted into the universal inert singularity mass only for the smallest fraction of a second, when all the gravitons of the universe are compacted together, with zero distance between all of them. This state is mandated by their small size and by their hence weak force.

The big bang is the shattering of the short-lived singularity mass into fragments that later became galactic clusters. This is inflation. The shattering is the start of movement of the shatters i.e. the start of reconversion of mass into energy, which is mass in motion. This reconversion proceeds at a constant rate since the big bang since the resolution of gravitons, their release from their shatters-clusters, proceeds at constant rate due to their weak specific force due to their small size.

Graviton's Energy-Mass Dualism:

Gravity Is The Monotheism Of The Universe
Everything in the dictionary and in the universe - nouns and verbs objects and processes - originate and derive from the energy-mass dualism, from the ongoing constant rate conversion of mass to energy, from the ongoing resolution-release of inert gravitons, mass, leaving the clusters of the fractured seed of the universe, singularity, and becoming energy, mass in motion.

The Graviton’s energy-mass dualism derives from its gravity, self-attraction, and its compactness.

Gravity:
the propensity of the gravitons – the elementary particles of the mass of the universe - to return to their singularity state of zero motion, of compacted zero inter-particle distance.

Compactness:
the default particle’s size and shape that enable zero inter-particle distance at singularity.

This, commonsensically, therefore possibly scientifically, is the matrix of the universe.

Dov Henis (comments from 22nd century)
http://universe-life.com/2012/02/03/universe-energy-mass-life-compilation/
Energy-Mass Poles Of The Universe
http://universe-life.com/2012/11/14/701/

PS:
Life is the obvious manifestation of energy-mass dualism. The sun’s energy, i.e. fast-moving mass particles, convert into slow-moving temporary mass formats…DH

In thinking about how the astronomers Burbidge conceived of the expansion/contraction of the U, I suspect the expansion continues until zero K and the phase change into 450 K occurs in an avalanche-style compression. We expand at leisure and contract as if we were never there.

Globular clusters are fascinating; what holds them together and keeps them orderly? Miles Mathis has a new paper: Blackbody Radiation is the Charge Field.

I think that dark matter & energy does not exist.Please read the abstract of my paper sent to ERS:http://t.co/DhiB9Zxp


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