NEW YORK: The first-ever triple quasar, a rare and awe-inspiring celestial phenomenon, has been located by the astronomers at the California Institute of Technology in the U.S.
Quasars (QUAsi StellAR Sources in full) are powerful sources of electromagnetic energy, including radio waves and light, believed to be powered by gas falling into black holes in the centers of galaxies. This happens when galaxies collide and merge. It is estimated that a single quasar can be a thousand times brighter than an entire galaxy of a hundred billion stars.
Scientists have discovered several thousands of quasars and dozens of double quasars, but this is for the first time that a triple quasar -- from three galaxies -- have been sighted.
When first sighted, the scientists thought it to be an illusion, caused by the splitting of light beams, but when they viewed it using telescopes at Hawaii's WM Keck Observatory, they confirmed it is a triplet involving three black holes.
The triple quasar was first observed by Prof George Djorgovski from the California Institute of Technology and colleagues after they studied a distant quasar named LBQS 1429-008. Astronomers at the Institute of Astronomy in Cambridge, England, led by Dr Paul Hewett, too had found another quasar during their studies that began in 1989. They first believed the second quasar to be the result of an effect known as gravitational lensing, caused by an object of large mass getting in the path of light coming from the quasar. This splits the light beams, in essence creating a double image. But, studies over the past several years led astronomers to confirm the finding was indeed a pair of close quasars.
Now, Prof Djorgovski's team has found a third, faint quasar. The scientists used one of the Keck's 10-meter telescopes along with measurements from the European Southern Observatory's 8.2-meter Very Large Telescope in Chile in identifying the third quasar. They also used computer modeling to find out whether it could be a case of gravitational lensing. If it had been lensing, there should have been four quasar sources and not three, they averred. There would have to be something hiding one of the images. Besides, there was no sign of any galaxy or cluster of galaxies, which could have caused the lensing effect.
The scientists have identified small, but significant differences in the properties of the three quasars.
Djorgovski says quasars are extremely rare objects and to find three is unprecedented. He also feels their distribution in the universe is not random and the process of collision and merging of galaxies and the supermassive black holes that reside at their centers may actually fuel these powerful sources of energy.
He calculated that the triple quasar is located about 10.5 billion light years away – a time when galaxy interactions were at their peak. He feels there could be existence of quadruple quasars.
The three quasars are all within about 160,000 light years of each other, which is more than 10 times closer than the nearest major galaxy to the Milky Way and is typical of galaxies that are observed to be interacting violently.
The astronomers have named the triple system QQQ 1432-0106.
The findings were presented at a meeting of the American Astronomical Society in Seattle Monday.
