A rare triple quasar located 9 billion light years away has been discovered by an international team of astronomers, according to a report released Tuesday in the journal Monthly Notices of the Royal Astronomical Society. It’s only the second time that a triple quasar has been found, and in honor of the occasion, they have given it the romantic name of QQQ J1519+0627.
The name quasar itself is short for “quasi-stellar radio sources” and goes back to the days when astronomers first discovered them as point sources of radio waves. Scientists eventually figured out that they were actually extremely large and extremely far away objects — not stars or even quasi-stars anywhere near our galaxy. The modern theory is that they are the cores of distant galaxies very far away — cores that contain huge black holes that may be in the process of swallowing the equivalent of about a billion stars the size of our sun.
The light from the quasars is highly redshifted, allowing scientists to calculate how much the universe has expanded since the light started traveling toward us and therefore how much time has passed during their travels toward earth. That gives us a rough idea of how far away they are. One quasar, 3C 273, is “only” a bit more than 2.4 billion years away and can be seen with amateur equipment, but most quasars can’t be seen without professional telescopes.
The triple quasar, at 9 billion light years away, presented a challenge.
Astrophysicist Michele Fumagalli, one of the people who participated in the search, explained that it took a lot of detective work as well as multiple telescope observations, to find the triplet. The purpose of seeking out these rarities? The team is trying “to go and find galaxy clusters that are in the act of forming, essentially,” he said.
When two or more quasars are found together, it could be evidence that they’re colliding to form a future cluster. In this case, two of the quasars seem to be already melting together, while the more distant third is perhaps just beginning to respond to the pull of gravity created by the other two.
One day, the triple quasar could be the seed of a giant super galaxy.
[artist's rendition of a quasar courtesy NASA]