Bubble-forming super-massive black hole found

Astronomers used a brand-new radio telescope to produce one of the best images ever made at the lowest frequencies of a galaxy 2000 times more massive than Milky Way, hosting in its centre one of the most massive black holes discovered so far.

Researchers found that this bubble is surprisingly young, just about 40 million years, which is a mere instant on cosmic time scales.

Like symbiotic species, a galaxy and its central black hole lead intimately connected lives. Some black holes actively accrete matter.

Part of this material do not fall into the black hole but is ejected in a narrow stream of particles, travelling at nearly the speed of light.

When the stream slows down, it creates a tenuous bubble that can engulf the entire galaxy. Invisible to optical telescopes, the bubble is very prominent at low radio frequencies.

The new International LOFAR Telescope is ideally suited to detect this low frequency emission.

Astronomers produced one of the best images ever of such a bubble, using LOFAR to detect frequencies from 20 to 160 MHz.

"The result is of great importance", says Francesco de Gasperin, lead author of the study that is being published in the journal Astronomy and Astrophysics.

"It shows the enormous potential of LOFAR, and provides compelling evidence of the close ties between black hole, host galaxy, and their surroundings," de Gasperin said.

The image was made during the test-phase of LOFAR, and targeted the giant elliptical galaxy Messier 87, at the centre of a galaxy cluster in the constellation of Virgo.

Every few minutes this black hole swallows an amount of matter similar to that of the whole Earth, converting part of it into radiation and a larger part into powerful jets of ultra-fast particles, which are responsible for the observed radio emission.

"This is the first time such high-quality images are possible at these low frequencies", says professor Heino Falcke, chairman of the board of the ILT and co-author of the study.