Extremely rare event: Scientists shocked to spot 4 quasars deep in space

It's a stunning sighting that is forcing scientists to question their fundamental theories about black holes and quasars themselves.
By Vicky Webb | May 16, 2015
A massive nebula dating back to the early universe is the home of four super-bright quasars within an amazingly close proximity to each other, forcing scientists to question some fundamental ideas they had about quasars in the first place.

It's rare to find a system with multiple quasars, since quasars themselves are a rare find. To find four quasars in one place is such an extreme unlikelihood that scientists are scratching their heads over this sighting, according to a Space.com report.

A quasar is one of the brightest objects in the universe, with a luminosity of 100 times that of the entire Milky Way, and they occur when mass falls into the accretion disk around the black hole, caused the black hole to blast out at an incredible amount of energy across the expanse of the universe.

Usually, there is about 100 million light-years between quasars, but these four quasars were found within a mere 700,000 light-years of each other, something that Joseph Hennawi of the Max Planck Institute for Astronomy in Germany would place at 1 in 10 million odds, according to the report.

Each galaxy has a supermassive black hole at its center that is millions of times the mass of our own sun, and material swirls around its rim at about the speed of light, blasting out a huge amount of energy before being swallowed up. If there is enough mass going into the black hole, it becomes a quasar, emitting a fantastic amount of life that can outshine its own galaxy.

Quasars don't live for very long though. They can last for between 10 and 100 million years, a blip in the 10 billion years a galaxy lasts. That's why it's so rare for astronomers to spot them, and therefore why four of them so close together is such a big surprise.

Hennawi and fellow researchers were looking at 29 quasars in order to spot a nebula of cool hydrogen gas, as quasars can illuminate nearby gas and help scientists to discover it.

The team used the Keck telescope in Hawaii after spotting a candidate, and found the brightest Lyman-alpha nebulae ever discovered, and they further discovered four quasars within that cloud of gas, a truly astonishing discovery.

A total of 500,000 quasars have been identified, but there are only a hundred known binary quasars. Only two triple-quasar systems have ever been found since 2007, and this is the first time a quadruple-quasar system has been recorded.

The findings were published in the journal Science.

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