The
figure shows a Hubble Space Telescope image of the central part of the
galaxy IC5063. The brighter part at the
centre shows the region where the jets driven by the supermassive black hole
are blasting material out of the galaxy. Credits: NASA/ESA and the Hubble Space
Telescope archive.
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.
Clive Tadhunter, from the
University's Department of Physics and Astronomy, said: "Much of the gas
in the outflows is in the form of molecular hydrogen, which is fragile in the
sense that it is destroyed at relatively low energies. I find it extraordinary
that the molecular gas can survive being accelerated by jets of highly
energetic particles moving at close to the speed of light."
"We suspected that
the molecules must have been able to reform after the gas had been completely
upset by the interaction with a fast plasma jet." says Morganti "Our direct observations of the phenomenon
have confirmed that this extreme situation can indeed occur. Now we need to work at describing the exact physics of the
interaction".
The results are published in Nature on the 6th of July
and they are connected to the project ‘Exploiting new radio
telescopes to understand the role of AGN in galaxy evolution', for which
Morganti received from the European Research Council an Advanced Grant of 2.5
Meuro last year.
More information:
About ASTRON
ASTRON is the Netherlands Institute for Radio
Astronomy (www.astron.nl). Its mission is to make discoveries in radio
astronomy happen, via the development of novel and innovative technologies, the
operation of world-class radio astronomy facilities, and the pursuit of
fundamental astronomical research.
Contact:
Prof. dr. Raffaella Morganti, ASTRON, RuG
E-mail: morganti@astron.nl
Tel: +31 (0)521-595100
Mob: +31 (0)6-11952523
Prof. dr. Tom A. Oosterloo, ASTRON, RUG
E-mail: oosterloo@astron.nl
Tel: +31 (0)521-595779
Dr Raymond Oonk, ASTRON, Leiden
E-mail: oonk@astron.nl
Tel: +31 (0)521-595100
Article:
'Jet acceleration of the fast molecular outflows in the Seyfert galaxy IC5063', C. Tadhunter, R. Morganti, M. Rose, J.B.R. Oonk, T. Oosterloo, , Nature, 6 July 2014
Text (in Dutch) & image: www.astronomie.nl/
