Australasian Science: Australia's authority on science since 1938

Dusty Surprise around Giant Black Hole

By David Reneke

The European Southern Observatory’s Very Large Telescope Interferometer has gathered the most detailed observations ever of the dust around the huge black hole at the centre of an active galaxy.

The full text of this article can be purchased from Informit.

Rather than finding all of the glowing dust in a doughnut-shaped torus around the black hole, as expected, the astronomers found that much of it is located above and below the torus.

These observations show that dust is being pushed away from the black hole as a cool wind – a surprising finding that challenges current theories and tells us how supermassive black holes evolve and interact with their surroundings.

Over the past 20 years, astronomers have found that almost all galaxies have a huge black hole at their centre. Some of these black holes are growing by drawing in matter from their surroundings, creating in the process the most energetic objects in the Universe – active galactic nuclei (AGN).

The central regions of these brilliant powerhouses are ringed by doughnuts of cosmic dust dragged from the surrounding space, similar to how water forms a small whirlpool around the plughole of a sink. It was thought that most of the strong infrared radiation coming from AGN originated in these doughnuts, but new observations of the nearby active galaxy NGC 3783 by the Interferometer at ESO’s Paranal Observatory in Chile have given a team of astronomers a surprise.

Although the hot dust, at 700–1000°C, is indeed in a torus as expected, they found huge amounts of cooler dust above and below this main torus forming a cool wind streaming outwards...

The full text of this article can be purchased from Informit.