Galactic super-volcano in action

HST image of M87

This Hubble Space Telescope image shows the central core and accompanying outflowing "jet" of the giant elliptical galaxy M87. In the centre of the galaxy there lurks a supermassive black hole.

A galactic “super-volcano” in the massive galaxy known as M87 is erupting and blasting gas outwards, as witnessed by NASA’s Chandra X-ray Observatory and the US National Science Foundation’s (NSF) Very Large Array (VLA) of radio telescopes.

The cosmic volcano is being driven by a giant black hole in the galaxy’s centre and preventing hundreds of millions of new stars from forming.

At a distance of about 50 million light-years, M87 is relatively close to Earth and lies at the centre of the Virgo cluster, which contains thousands of galaxies.

M87’s location, coupled with long observations over Chandra’s lifetime, has made it an excellent subject for investigations of how a massive black hole impacts its environment.

Core of the galaxy M87

This is the core of the galaxy M87, seen at X-ray and radio wavelengths. A huge black hole, hiding in the middle, is ejecting energetic particles that push gas outwards. That gas would ordinarily form millions of new stars, so the black hole's activity is acting like a brake on star formation.

“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,” said 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 space around M87 is filled with hot gas glowing in X-ray light, which has been detected by Chandra. As this gas cools, it should fall in toward the M87’s centre where it could continue to cool even faster and form new stars.

However, radio observations with the Very Large Array suggest that in M87 jets of very energetic particles produced by the black hole interrupt this process. These jets lift up the relatively cool gas near the centre of the galaxy and produce shock waves in the galaxy’s “atmosphere” because of their supersonic speed.

In M87, the plumes of cooler gas being lifted upwards contain as much mass as all of the gas contained within 12,000 light-years of the centre of the galaxy cluster.

This shows the black hole-powered volcano is very efficient at blasting the galaxy free of the gas that would otherwise cool down and form stars.

The eruption in M87 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.

Adapted from information issued by Chandra X-ray Centre.

Images courtesy Tod R. Lauer, Sandra M. Faber / NASA / X-ray (NASA / CXC / KIPAC / N. Werner, E. Million et al); radio (NRAO / AUI / NSF / F. Owen)

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