Call it the cosmic equivalent of winning the lottery: for the first time ever, astronomers have discovered four of the rare, super-luminous celestial objects known as quasars arrayed in close proximity to one another.
Quasars are typically separated by vast distances, and the discovery of this "quasar quartet" has been characterized as either a one-in-10-million coincidence or evidence that ideas about quasars need to be revised.
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In this false-color image, arrows indicate the four quasars that are embedded in a giant nebula of cool, dense gas (shown in blue).
"Multiple-quasar systems are rare, because quasars themselves are rare," Dr. Joseph Hennawi, a cosmologist at Germany's Max Planck Institute for Astronomy and the leader of the team of astronomers who made the discovery, told Space.com. "The typical distance between any two quasars is about 100 million light-years of each other, whereas we found four quasars within 700,000 light-years of each other."
Nearly 500,000 quasars have been identified so far, according to Space.com. But scientists know of only about 100 binary quasars and only a couple of triple quasars.
This is the first four-quasar system ever observed.
The newfound quasars were discovered with the help of Hawaii's W.M. Keck Observatory. They lie in a giant nebula that for obvious reasons has been dubbed the "Jackpot nebula." The nebula spans about one million light-years and has a mass of about 100 billion suns, according to EarthSky.com.
What's a quasar? Quasars are supermassive black holes at the heart of galaxies that are extremely remote and thus extremely ancient. As these monsters gobble up gas that surrounds them, they shine hundreds of times more brilliantly than their host galaxies, according to Science magazine--even though the galaxies contain up to hundreds of billions of stars.
All supermassive black holes in big galaxies are believed to undergo a quasar phase, according to a written statement issued by the institute. But this phase lasts for only about 10 million years--a very brief time given galaxies' much longer ages of 10 billion years and counting.
Time for revisions. So did the astronomers who discovered the quasar quartet really get lucky--or does the discovery suggest that revisions are needed to the models for how quasars form?
"I think that our thinking needs to be revised," Hennawi told The Huffington Post in an email. "We have theories about what causes a supermassive black hole at the center of a galaxy to turn on as a quasar, and typically something like a collision between two galaxies or an abundance of fuel for the black holes to swallow is the factor that turns on the quasar phase. These theories, however, would not predict the existence of this quartet."
What's next? To figure out what might explain the existence of the quartet, the astronomers will try to find similar systems.
"This sounds obviously like a daunting task since the odds of four quasar [discovery] is one in 10 million," Hennawi said in the email. "However, we have a clean recipe for how to proceed."
A paper describing the discovery was published in the journal Science on May 15, 2015.