nov 282012


Virginia Tech physicists have discovered a quasar with the most energetic outflow ever seen, a finding that may answer questions about how the mass of a galaxy is linked to its central supermassive black hole mass and why there are so few large galaxies in the Universe.

This artist’s impression shows the material ejected from the region around the supermassive black hole in the quasar SDSS J1106+1939. This object has the most energetic outflows ever seen, at least five times more powerful than any that have been observed to date. Quasars are extremely bright galactic centers powered by supermassive black holes. Many blast huge amounts of material out into their host galaxies, and these outflows play a key role in the evolution of galaxies. But, before this object was studied, the observed outflows weren’t as powerful as predicted by theorists. The very bright quasar appears at the center of the picture and the outflow spreads about 1000 light-years out into the surrounding galaxy. Image Credit: ESO/L. Calçada

Researchers studied the quasar known as SDSS J1106+1939 in great detail using the European Southern Observatory’s Very Large Telescope in Paranal, Chile – the world’s most advanced visible-light astronomical observatory, and found the most energetic quasar outflow ever discovered.

The rate that energy is carried away by the huge mass of material ejected is equivalent to two trillion times the power output of the Sun.

“This is about 100 times higher than the total power output of the Milky Way galaxy — it’s a real monster outflow,” said Nahum Arav, an associate professor of physics in College of Science and leader of the research team, which includes Benoit Borguet, now a postdoctoral researcher now at the University of Liege, Belgium; Doug Edmonds and Carter Chamberlain, both graduate research assistants at Virginia Tech; and Chris Benn, a collaborator who works with the Isaac Newton Group of Telescopes in Spain.

Theorists have predicted energy flows of this magnitude, and simulations have suggested these outflows impact the galaxies around them, but it has all been speculation — until now.

“For the last 15 years many theorists have said that if there were such powerful outflows it would help answer many questions on the formation of galaxies, on the behavior of black holes, and on the enrichment of the intergalactic medium with elements other than hydrogen and helium,” Arav said. “This discovery means we can better explain the formation of galaxies. There are hundreds of people doing the theoretical side of the work. They hypothesize outflows in their simulations, and now we’ve found an outflow in the magnitude that has only been theorized in the past. Now they can refine their already impressive models and base them on empirical data.”

Quasars are light phenomenon produced as material falls into a black hole producing a huge amount of energy. The bigger the black hole, the bigger the quasar. The Milky Way, according to Arav, is a big galaxy with a “smallish” black hole. The black hole at the heart of quasar SDSS J1106-1939 is massive, estimated to be a thousand times heavier than the supermassive black hole in the Milky Way.

And while black holes are noted for pulling material in, quasars accelerate some of the material and eject it at high speed. The larger the quasar, the more material it can take, the higher speed it can accelerate it, and the further it can eject the material.

“Quasars have been known for 40 years,” Arav explained. “We were able to figure out how to measure the mass of mechanical energy the black hole is putting out – by calculating the size of the outflow, how far away from the black hole it was, and how much mass it had per unit area.”

The quasar’s outflow is at least five times more powerful than the previous record holder, also discovered by Arav and his research group in 2009, and material from the outflow is inferred to be about a thousand light years away from the black hole at the heart of quasar SDSS J1106-1939.

Every year, according to the team’s analysis, a mass of more than 400 times that of the Sun is streaming away from the quasar at a speed of 8,000 kilometers per second.

“I’ve been looking for something like this for a decade,” Arav said, “so it’s thrilling to finally find one of the monster outflows that have been predicted.”

The findings were released today (Wednesday, Nov. 28, 2012) by the European Southern Observatory.

Source: Virginia Tech via AlphaGalileo

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