Powerful jets spew out of black hole - Video

Some 2 million years ago, around the time our ancestors were learning to walk upright, a light appeared in the night sky, rivalling the moon for brightness and size but it was more fuzzball than orb.

The glow came from the supermassive black hole at our galaxy's heart suddenly exploding into life.

This novel picture emerges from work announced this week at a conference in Sydney, Australia, which ingeniously pieces together two seemingly unrelated, outstanding galactic puzzles.

As well as offering a welcome way to solve both, it gives us an unexpected glimpse of how the cosmos might have appeared to Earthlings 2 million years ago (see "Which species saw the flare?").

Joss Bland-Hawthorn

"That is when we had Homo erectus running around Earth," says Joss Bland-Hawthorn of the University of Sydney, who led the team behind the work.

It also paints supermassive black holes as unpredictable, and capable of generating some of the brightest flares in the universe, almost on a whim.

That in turn throws up the possibility of modern humans being treated to a similar sight sometime in the future – thankfully we are too far away for a flare-up to pose a risk.

Powerful jets discovered blowing material out of galaxy

Radio-Telescope Image of the galaxy 4C12.50, nearly 1.5 billion light-years from Earth. 

Inset shows detail of location at end of superfast jet of particles, where a massive gas cloud (yellow-orange) is being pushed by the jet. 

Credit: Morganti et al., NRAO /AUI /NSF

Astronomers using a worldwide network of radio telescopes have found strong evidence that a powerful jet of material propelled to nearly light speed by a galaxy's central black hole is blowing massive amounts of gas out of the galaxy.

This process, they said, is limiting the growth of the black hole and the rate of star formation in the galaxy, and thus is a key to understanding how galaxies develop.

Astronomers have theorized that many galaxies should be more massive and have more stars than is actually the case.

Scientists proposed two major mechanisms that would slow or halt the process of mass growth and star formation -- violent stellar winds from bursts of star formation and pushback from the jets powered by the galaxy's central, supermassive black hole.

Raffaella Morganti

"With the finely-detailed images provided by an intercontinental combination of radio telescopes, we have been able to see massive clumps of cold gas being pushed away from the galaxy's center by the black-hole-powered jets," said Raffaella Morganti, of the Netherlands Institute for Radio Astronomy and the University of Groningen.

The scientists studied a galaxy called 4C12.50, nearly 1.5 billion light-years from Earth. They chose this galaxy because it is at a stage where the black-hole "engine" that produces the jets is just turning on.

As the black hole, a concentration of mass so dense that not even light can escape, pulls material toward it, the material forms a swirling disk surrounding the black hole.

Processes in the disk tap the tremendous gravitational energy of the black hole to propel material outward from the poles of the disk.

At the ends of both jets, the researchers found clumps of hydrogen gas moving outward from the galaxy at 1,000 kilometers per second.

One of the clouds has much as 16,000 times the mass of the Sun, while the other contains 140,000 times the mass of the Sun. The larger cloud, the scientists said, is roughly 160 by 190 light-years in size.

"This is the most definitive evidence yet for an interaction between the swift-moving jet of such a galaxy and a dense interstellar gas cloud," Morganti said.

"We believe we are seeing in action the process by which an active, central engine can remove gas -- the raw material for star formation -- from a young galaxy," she added.

The scientists also said their observations indicate that the jets from the galaxy's core can stretch and deform clouds of interstellar gas to expand their "pushing" effect beyond the narrow width of the jets themselves.

In addition, they reported that, at 4C12.50's stage of development, the jets may turn on and off and so periodically repeat the process of removing gas from the galaxy.

In July, another team of scientists, using the Atacama Large Millimeter/submillimeter Array (ALMA), announced they had found gas being blown from a more-nearby galaxy, called NGC 253, by an intense burst of star formation.

"Both processes are thought to be at work, often simultaneously, in young galaxies to regulate the growth of their central black holes as well as the rate at which they can form new stars," Morganti said.

Morganti and her team used radio telescopes in Europe and the U.S., combining their signals to make one giant, intercontinental telescope.

Journal Reference:
R. Morganti, J. Fogasy, Z. Paragi, T. Oosterloo, M. Orienti. Radio Jets Clearing the Way Through a Galaxy: Watching Feedback in Action. Science, 2013; 341 (6150): 1082 DOI: 10.1126/science.1240436

Composite Image of Powerful Jets Spewing From Supermassive Black Hole

This image of the galaxy known as 4C+29.30 contains X-ray data from NASA's Chandra X-ray Observatory (blue), optical light obtained with the Hubble Space Telescope (gold) and radio waves from the NSF's Very Large Array (pink).

CREDIT: X-ray: NASA/CXC/SAO/A.Siemiginowska et al; Optical: NASA/STScI; Radio: NSF/NRAO/VLA

Supermassive black holes are thought to lie at the center of nearly every galaxy, sucking up dust and gas and other material that allows them to grow to enormous sizes.

A stunning composite image of a galaxy 850 million light-years from Earth shows the power of one of these cosmic monsters spewing out humongous jets.

Astronomers pieced together a picture of the galaxy known as 4C+29.30 using data from different telescopes, including X-ray data from NASA's Chandra X-ray Observatory, optical data from the Hubble Space Telescope and radio waves from the Very Large Array in New Mexico.

The X-ray spectrum exposes the hot gas in this galaxy, with particularly bright spots at the center that represent million-degree gas pooling around the supermassive black hole, which is thought to be 100 million times heavier than our sun. Sometimes, as this matter falls in toward the black hole, it gets accelerated and hurled outward.

This triggers a flare-up in the two huge particle jets that radio data show to be racing at millions of miles per hour away from the black hole. Bright orbs at the end of the jets mark where extremely high energy electrons have crashed into clumps of material in the galaxy.

By both heating the gas in these clumps and dragging cool gas along for the ride, these jets sometimes deprive the supermassive black hole of its fuel supply, making it temporarily go hungry, researchers say.