MessageToEagle.com - The evidence for dark matter stems primarily from observations of the velocities of galaxies
within galaxy clusters.
Researchers know about its existence and that there is no empty space in the universe.
The inter-galactic space is filled with a large amount of unseen matter.
It constitutes about 22 percent of the present-day universe while ordinary matter constitutes only 4.5 percent.
An important question still remains - Where is most of the dark matter in the universe?
Galaxies have no definite "edges", the new research concludes. Instead galaxies have long outskirts of dark matter
that extend to their nearby galaxies; the inter-galactic space is not empty but filled with dark matter.
The two images illustrate the effect of gravitational lensing. A massive galaxy at the center of the right
panel causes the images of the background galaxies (white spots) to be enlarged and brightened.(Image credit:
Joerg Colberg, Ryan Scranton, Robert Lupton, SDSS, http://www.sdss.org/news/releases/20050426.magnification.html)
Using large-scale computer simulations of cosmic structure formation and recent observational data of gravitational lensing,
researchers at IPMU and Nagoya University reveal how dark matter is distributed around galaxies.
They showed that galaxies have extended outskirts of dark matter, well beyond the region where stars exist.
The dark matter distribution is well organized but extended to intergalactic space, whereas luminous components such as stars
are bounded within a finite region.
More interestingly, the estimated total amount of dark matter in the outskirts of the galaxies explains the gap between the
global cosmic mass density and that derived from galaxy number counting weighted by their masses.
Only recently, images of millions of galaxies from Sloan Digital Sky Survey (SDSS) made it possible to derive an averaged
mass distribution around the galaxies.
A computer simulation of formation of galaxies in the expanding Universe as predicted by modern cosmological scenario.
"Galaxy" is the large central object surrounded by numerous dark matter satellites. (Credit: Anatoly Klypin, SDSS)
A computer simulation shows dark matter is distributed in a clumpy but organized manner. In the figure, high
density regions appear bright whereas dark regions are nearly, but not completely, empty.Credits: IPMU and Nagoya University
Also in 2010, an international research group led by Brice Menard then at University Toronto and Masataka Fukugita at IPMU
used twenty four millions galaxy images from SDSS and successfully detected gravitational lensing effect caused by dark
matter around the galaxies.
They determined the projected matter density distribution over a distance of a hundred million light years from the center
of the galaxies.
A long standing mystery on where the missing dark matter is now solved by the research. The research article has been
published in the February 10th issue of The Astrophysical Journal.
Stars In The Milky Way Move In Mysterious Ways
Appearently we still have a lot to learn about the stars in the Milky Way.
Something strange has been noticed about the stars in our galaxy.
Rather than moving in circles around the center of the Milky Way, all the stars in our Galaxy are travelling along different paths,
moving away from the Galactic center.
Black Gaps In The Sky Puzzle Astronomers
Very dark isolated interstellar clouds of very cold gas like black gaps have puzzled astronomers for more than a century.
Looking at the sky in the direction of the constellation Sagittarius, it is clear that there are extremely dark,
opaque knots of gas and dust especially in the region toward the center of our Milky Way.
Invader From Another Galaxy
This alien intruder from another galaxy is in many ways different from other exoplanets observed by astronomers.
Located about 2000 light-years from Earth in the southern constellation of Fornax (the Furnace), the Jupiter-like planet orbits a dying star of
extragalactic origin and risks to be engulfed by it.
Power To See Most Distant Objects In The Universe
The 3C294, is one of the most distant galaxies recorded by Chandra, the most sophisticated X-ray observatory ever built.
The cluster 3C294 is even 40 percent farther (!) than the next most distant x-ray galaxy cluster.
Chandra focus on X-rays from high-energy regions of the Universe and see the invisible.
It is so sensitive that it can capture images of particles as they disappear into a black hole deep in outer space.
"Pillars Of Creation" Are Gone
Every time you look at the beautiful and famous image of the Pillars of Creation taken by Hubble back in 1995,
you are actually admiring something that no longer exists.
In fact, the Pillars of Creation were already long gone by the time the image was captured!