A binary quasar discovered in 1989 proves to be trio ...

Jan 9, 2007 12:19 GMT  ·  By

Quasars (photo) are one of the celestial bodies that sparked the imagination of astronomy lovers.

They are powerful sources of energy, powered by "supermassive" black holes. What astronomers first thought it was just an illusion, caused by a lens effect, has proven to be the first discovered triple quasar.

The team employed Hawaii's WM Keck Observatory to check if the system really involves three black holes.

Each quasar expels huge quantities of electromagnetic energy, including visible light and radio waves, being fueled by gas falling into a black hole at the center of a galaxy and the process is most efficient when galaxies knock and merge.

Just one quasar has a thousand times more energy and brightness than an entire galaxy of a hundred billion stars.

The team from the California Institute of Technology in Pasadena was investigating the two quasar group LBQS 1429-008, discovered in 1989. When this pair was found, the researchers believed that one of the quasars was a mirage caused by a lensing effect, which appears when a large object gets in the path light emitted from the quasar, splitting it and creating a double image.

Since 1989, astronomers discovered around 100,000 quasars and dozens of binary quasars. But the Keck's 10m telescopes and measurements from the European Southern Observatory's 8.2m telescope in Chile revealed a third, faint quasar in LBQS 1429-008.

Gravitational lensing brought no explanation. The astronomers did not find a galaxy, or cluster of galaxies that could have caused a lensing effect. They also spotted small, but significant differences in the properties of the three quasars. "Quasars are extremely rare objects," says Professor George Djorgovski, team's leader. "To find three is unprecedented".

Djorgovski believes that the quasars distribution in the Universe is not random, but the collision and merging of galaxies, with their supermassive central black holes, may actually fuel them. This could be an explanation for the unexpected high number of binary quasars. The quasars appeared during a period when interactions between galaxies were at their height. They may even regulate galaxies' and their supermassive black holes' growth.

Djorgovski thinks there may also be quadruple quasars.