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Showing posts with label collision. Show all posts
Showing posts with label collision. Show all posts

Monday 30 March 2015

What Is Dark Matter? Colliding Galaxy Clusters May Help Find Answer

Dark matter is a hypothetical kind of matter that cannot be seen with telescopes but accounts for most of the matter in the universe.  Dark matter is estimated to constitute 84.5% of the total matter in the universe. It has not been detected directly, making it one of the greatest mysteries in modern astrophysics.

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Hubble Image of Galactic Collision 

A study of 72 large cluster collisions shows how dark matter in galaxy clusters behaves when they collide.

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Image Showing How two Galaxies Collides


Astronomers have used data from NASA’s Hubble Space Telescope and the Chandra X-ray Observatory to find that dark matter interacts with itself less than previously thought. In an effort to learn more about dark matter, astronomers observed how galaxy clusters collide with each other -- an event that could hold clues about the mysterious invisible matter that makes up most of the mass of the universe.

As part of a new study, published in the journal Science on Thursday, researchers used the Hubble telescope to map the distribution of stars and dark matter after a collision. They also used the Chandra observatory to detect the X-ray emission from colliding gas clouds.

“Dark matter is an enigma we have long sought to unravel,” John Grunsfeld, assistant administrator of NASA’s Science Mission Directorate in Washington, said in a statement. “With the combined capabilities of these great observatories, both in extended mission, we are ever closer to understanding this cosmic phenomenon.”

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Here are images of six different galaxy clusters taken with NASA's Hubble Space Telescope (blue) and Chandra X-ray Observatory (pink) in a study of how dark matter in clusters of galaxies behaves when the clusters collide. A total of 72 large cluster collisions were studied.  NASA and ESA

According to scientists, galaxy clusters are made of three main components -- galaxies, gas clouds and dark matter. During collisions, the gas clouds bump into each other and gradually slow down. Galaxies, on the other hand, are much less affected by this process, and because of the huge gaps between the stars within them, galaxies do not slow each other down.

“We know how gas and stars react to these cosmic crashes and where they emerge from the wreckage,” David Harvey of the École Polytechnique Fédérale de Lausanne in Switzerland, and the study’s lead author, said in the statement. “Comparing how dark matter behaves can help us to narrow down what it actually is.”

The researchers studied 72 large galaxy cluster collisions and found that, like galaxies, the dark matter continued straight through the collisions without slowing down much, meaning that dark matter do not interact with visible particles.

“There are still several viable candidates for dark matter, so the game is not over. But we are getting nearer to an answer,” Harvey said.

Source : IBT times

Saturday 31 January 2015

A NEAR-COLLISION STRETCHED THIS GALAXY LIKE A "TAFFY PULL"

Hubble image of NGC 7714 Two galaxies drifted too close together between 100 and 200 million years ago, and began to drag at and disrupt one another’s structure and shape 

At first glance,it looks like a giant rollercoaster loop.
However, this incredible image actually shows a ‘river’ of Sun-like stars that has been pulled deep into space by the gravitational tug of a bypassing galaxy
The golden loop is made of sun-like stars that have been pulled deep into space, far from the galaxy’s centre.
Experts say the galaxy, called NGC 7714, has witnessed some violent and dramatic events in its recent past.
Tell-tale signs of this brutality can be seen in NGC 7714’s strangely shaped arms, and in the smoky golden haze that stretches out from the galactic centre, they say.
The culprit is a smaller companion named NGC 7715, which lies just out of the frame of this image.
As a result, a ring and two long tails of stars have emerged from NGC 7714, creating a bridge between the two galaxies. This bridge acts as a pipeline, funnelling material from NGC 7715 towards its larger companion and feeding bursts of star formation. Most of the star-forming activity is concentrated at the bright galactic centre, although the whole galaxy is sparking new stars.
The galaxy is located approximately 100 million light-years from Earth in the direction of the constellation Pisces.
Astronomer believe that our Galaxy will also collide with its companion galaxy Andromeda after 4 billion years . Here is the Simulation of Galactic collision
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Source : Dailymail , io9