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It takes jet power to clean a galaxy!!

Submitter: Raffaella Morganti, Tom Oosterloo & Zsolt Paragi
Description: In a paper we publish today in Science, the first clear evidence is presented that radio jets from the supermassive black hole in the centre of a galaxy clears gas away from the galaxy.

Astronomers have been puzzled for quite a while by the fact that many galaxies in the Universe seem to be depleted of their gas and, as a consequence, are not able any more to form any new stars. One of the main results obtained with the WSRT in recent years is the discovery of the existence of very fast outflows of cold gas in a number of galaxies that have an active galactic nucleus, and it was suspected that these outflows play an important role in making galaxies gas poor. However, the mechanism driving these outflows was not understood because with the WSRT one can establish that outflows occur, but the resolution of the WSRT is not good enough to determine where in the galaxy the outflow occurs.

By using global VLBI observations we have been able, in one of the galaxies where WSRT data showed a fast outflow exists, to directly map the distribution of the outflowing gas and directly witness the interaction between the plasma jet and the gas and how it is pushed out from a galaxy. Despite the strong push received from the jet, the temperature of the gas is low. But this is exactly what is needed to make theory of galaxy formation and observations to agree. Cold gas is the fundamental building block of new stars. If this gas is expelled, star formation stops. The results of this new study could not have been in better agreement with our expectations and the expectations from numerical simulations.

The success of the observations means that VLBI is a suitable technique to study the effect of the super massive black hole on the gas in its vicinity and we hope to use this technique to study more objects where jet-driven gas outflows are suspected to exist.

As final important note, we would like to emphasize that part of this study has been done as ASTRON/JIVE Summer Student project by Judit Fogasy (from Budapest).
Not a bad result for a student just starting her PhD!!!!

More can be found in Radio Jets Clearing the Way Through a Galaxy: Watching Feedback in Action, R. Morganti, J. Fogasy, Z. Paragi, T. Oosterloo, M. Orienti, Science, 6 September 2013 http://de.arxiv.org/abs/1309.1240
Copyright: ASTRON
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