Dwingeloo, 7 July 2014
New research led by Clive Tadhunter (Sheffield University) and including Raffaella Morganti, Tom Oosterloo (ASTRON/Kapteyn Institute Groningen University) and Raymond Oonk (ASTRON/Leiden University), has solved a long-standing mystery surrounding the evolution of galaxies, which deepens our understanding of the future of the Milky Way.
The supermassive black holes in the cores of some galaxies drive massive outflows of molecular hydrogen gas. As a result, most of the cold gas is expelled from the galaxies. Since cold gas is required to form new stars, this directly affects the galaxies’ evolution.
These outflows are now a key ingredient in theoretical models of the evolution of galaxies, but it has long been a mystery as to how they are accelerated.
The study provides the first direct evidence that the molecular outflows are accelerated by energetic jets of electrons that are moving at close to the speed of light. Such jets are propelled by the central supermassive black holes.
Using the ESO Very Large Telescope in Chile to observe the nearby galaxy IC5063, the researchers found that the molecular hydrogen gas is moving at extraordinary speeds – 1 million kilometers per hour – at the locations in the galaxy where its jets are impacting regions of dense gas.
These findings help us further understand the eventual fate of our own galaxy, the Milky Way, which will collide with neighbouring galaxy Andromeda in about 5 billion of years. As a result of this collision, gas will fall to the centre of the remnant of this collision, but the jets coming from the central supermassive black hole will, in a way similar to what is now observed in IC 5063, eject the gas from the system, preventing the formation of new stars and growth of the newly formed galaxy.