A team of researchers has discovered a quasar quartet at the edge of the visible universe. Unlike normal quasars which are usually scattered far and wide these ones are extremely close. This discovery could change what scientists have known about the formation of galaxies and galaxy clusters. The study was published in the journal Science.
A quasar represents the active state of a black hole. When material gets near a black hole it creates an accretion disk which spins in the gravity of the black hole and it consequently acquires a millions of degrees temperature. This leads to huge amounts of radiation which is blasted outward by the magnetic field of the black hole for millions of light years. That’s how the quasar is extremely bright and it can be seen from great distances.
Quasars are considered to be the nuclei of early galaxies. They are tremendously rare and they are separated by hundreds of millions of light-years. That is why this discovery is so unexpected. Scientists say that there are one in ten million odds to find out a quadruple quasar. The four quasars in the group are only 650.000 light-years away from each other.
One of the authors of the study, Joseph Hennawi of the Max Planck Institute for Astronomy (Heidelberg, Germany) that when scientists discover something as improbable as this case it means that they are either very lucky or they have to change their theory.
The quasars are surrounded by a massive nebula of cool, dense hydrogen gas which the research team has called the “Jackpot nebula” because of the rare quasars in it. The existence of multiple quasars indicates the formation of protoclusters, which are the forerunners of huge galaxy clusters. This combined with the fact that the quasars are surrounded by the cold gaseous nebula questions the quasar evolution and the even the way in which massive cosmic structures were formed.
Study co-author Sebastiano Cantalupo of ETH Zurich and UC Santa Cruz remarked:
“Our current models of cosmic structure formation based on supercomputer simulations predict that massive objects in the early universe should be filled with rarefied gas that is about ten million degrees, whereas this giant nebula requires gas thousands of times denser and colder.”
The unusual quasars probably do not exist by chance in the unusual nebula. The nebula might provide the cold gas which functions as fuel and allows the quasars to remain active and bright longer than usual.
Image Source: National Geographic