(From top) Dark matter in Galaxy Cluster MACS J00254.4-1222, captured with Nasa’s Chandra X-ray Observatory and the Hubble Space Telescope; the Chandra X-Ray telescope;Subrahmanyan Chandrasekhar receives the National Medal of Science from President Lyndon Johnson in 1967. (Nasa/Edinburgh University)

London, Dec. 26: Pictorial evidence of the existence of “dark matter”, which is normally invisible to the naked eye, has been found deep in space by Nasa’s Chandra X-ray Observatory, the telescope named after the Indian Nobel Prize-winning physicist Subrahmanyan Chandrashekhar.

A remarkable photograph released today by Edinburgh University shows how the Chandra telescope, which can detect X-rays, has been able to separate out the pink of very hot gases from the blue of the relatively inert dark matter after a collision in space.

Scientists say there is six times as much dark matter as other matter in the universe but the former is the “scaffolding” necessary for the formation of planets, stars and galaxies — and life as we know it. It is a bit like the frame around which Durga idols take shape.

The latest study was carried out by an international team of astronomers.

The breakthrough picture depicts what amounts to a “cosmic car crash”, involving two clusters made up of hundreds of galaxies and closing at millions of miles an hour, which took place a long time ago and very far away. Although it sounds like something out of a Star Wars film, the intergalactic smash happened about 100 million years ago and about half way across the universe at a distance of 5.7 billion light years.

The picture is possible thanks to the Chandra X-ray Observatory, Nasa’s most powerful X-ray telescope which was launched from the space shuttle Columbia on July 23, 1999. It works in tandem with Nasa’s three other Great Observatories, including the Hubble Space Telescope, which was the first to be launched.

Unlike the Hubble’s circular orbit that is relatively close to the earth, the Chandra has been placed in a highly elliptical orbit. At its closest approach to the earth, the observatory travels at an altitude of about 16,000km. At its farthest, 133,000km, it travels almost one-third of the way to the moon.

Because of this elliptical orbit, the telescope circles the earth every 64 hours, carrying it far outside the belts of radiation that surround the earth. This radiation, while harmless to life on the earth, can overwhelm the observatory’s sensitive instruments.

The X-ray observatory is outside this radiation long enough to take 55 hours of uninterrupted observations during each orbit — hence today’s revealing photograph has become possible and allows a better understanding of the Big Bang, how the universe came into being and the crucial role played by dark matter.

Nasa is proud that “Chandra allows scientists from around the world to obtain unprecedented X-ray images of exotic environments to help understand the structure and evolution of the universe”.

Astronomer Richard Massey, from the University of Edinburgh, said the universe could not have formed “without the dark matter scaffolding being there in the first place. It is very important and crucial. Life wouldn’t exist without this stuff”.

The picture shows the effect of the collision. The hot gases, indicated by pink, slowed down, but not the blue, shown by the wider spread of the latter. Scientists say the separation of the pink and blue provides evidence for dark matter and backs the view that dark matter particles react only very weakly with each other or not at all, apart from the pull of gravity.

“The unusual configuration of this cosmic collision enables astronomers to study mysterious, invisible dark matter,” Massey added.