Astronomers from Chalmers University of Technology and Onsala Space Observatory in Sweden have observed an extremely intense magnetic field beyond anything previously detected very close to a supermassive black hole in a distant galaxy.

Our discovery is a giant leap in terms of observing frequency, thanks to the use of ALMA, and in terms of distance to the black hole where the magnetic field has been probed.

said co-author Sebastien Muller.

Up until now, astronomers have only detected weak magnetic fields located several light-years away from black holes. But in this new study — appear in the 17 April 2015 issue of the journal Science — astronomers used the Atacama Large Millimeter to detect signals directly related to a strong magnetic field near to the event horizon of the supermassive black hole into the heart of the distant galaxy PKS 1830-211.

According to Ivan Marti-Vidal, lead author of the research:

The new observation helps astronomers understand the structure and formation of these massive inhabitants of the centres of galaxies and the twin high- speed jets of plasma they frequently eject from their poles.

The researchers measured the strength of the magnetic field by studying the way in which light was polarized as it moved away from the black hole.

Polarisation is an important property of light and is much used in daily life, for example in sun glasses or 3D glasses at the cinema.

said Dr Marti-Vidal,

When produced naturally, polarisation can be used to measure magnetic fields, since light changes its polarisation when it travels through a magnetised medium. In this case, the light that we detected with Alma had been travelling through material very close to the black hole, a place full of highly magnetised plasma.

We have found clear signals of polarisation rotation that are hundreds of times higher than the highest ever found in the Universe

Our discovery is a giant leap in terms of observing frequency, thanks to the use of ALMA, and in terms of distance to the black hole where the magnetic field has been probed – of the order of only a few light-days from the event horizon. These results, and future studies, will help us understand what is really going on in the immediate vicinity of supermassive black holes.