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Galactic supervolcano
spews into space

Posted: 20 August 2010

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A new image created from data from the Chandra X-ray Telescope Observatory and Very Large Telescope Array (VLA) reveal a giant eruption of gas blasting from the core of massive galaxy M87.

The eruption, which scientists are likening to a volcanic eruption on Earth, is driven by a supermassive black hole that lies at the centre of the galaxy, which resides 50 million light years away in the heart of Virgo Cluster.

Scientists compare the interaction of M87's jets with the surrounding gas with the volcanic eruption of Iceland's Eyjafjallajokull. Image: X-ray (NASA/CXC/KIPAC/N. Werner, E. Million et al); Radio (NRAO/AUI/NSF/F. Owen).

“Our results show in great detail that supermassive black holes have a surprisingly good control over the evolution of the galaxies in which they live,” says Norbert Werner of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University and the SLAC National Accelerator Laboratory, who led one of two papers describing the study. “And it doesn’t stop there. The black hole’s reach extends ever farther into the entire cluster, similar to how one small volcano can affect practically an entire hemisphere on Earth.”

The galaxy cluster surrounding M87 is filled with hot gas, which, as it falls towards the galaxy centre, should form new stars. But radio observations with the VLA show that jets of energetic particles speeding out from the black hole are preventing this process.

The scientists compare the process with the recent volcanic eruption of Eyjafjallajokull volcano in Iceland, where pockets of hot gas blasted through layers of the lava to generate shock waves that rippled through the grey smoke of the volcano, dragging dark ash up into the atmosphere. Similarly, the high energy particles produced around M87's black hole power through the cluster, lifting up the coolest gas at the centre and creating shockwaves where the jets slam into the gas.

The cluster surrounding M87 is filled with hot gas glowing in X-ray light (shown in blue) that is detected by Chandra but radio observations with the VLA (red-orange) suggest that jets of very energetic particles produced by M87's black hole interrupt this process. The Chandra image was based on an observation lasting almost 7 days. X-ray data from ESA’s XMM-Newton was also used. Image: X-ray (NASA/CXC/KIPAC/N. Werner, E. Million et al); Radio (NRAO/AUI/NSF/F. Owen)

“This analogy shows that even though astronomical phenomena can occur in exotic settings and over vast scales, the physics can be very similar to events on Earth,” says co-author Aurora Simionescu also of the Kavli Institute.

The scientists say that the eruption that lifted up the cooler gas must have occurred about 150 million years earlier, but a smaller eruption only about 11 million years earlier produced the shock wave. The observations demonstrate the black hole's efficiency in clearing out the star-forming gas from the central region of the galaxy.

“This gas could have formed hundreds of millions of stars if the black hole had not removed it from the centre of the galaxy,” says lead author Evan Million from Stanford University. “That seems like a much worse disruption than what the airline companies on Earth had to put up with earlier this year!”