Unusual ‘magnetic discovery’ could explain galaxy formation
A magnetic field wrapped around a galaxy’s spiral arm could shape our understanding of how galaxies are made
A combined radio and optical image of IC 342, using data from both the VLA and the Effelsberg telescope. Lines indicate the positioning of magnetic fields in the galaxy. Image Credit: R. Beck, MPIfR, NRAO/AUI/NSF
A detailed look at a nearby galaxy has revealed a magnetic field wrapped around one of the structure’s spiral arms and, according to astronomers at the Max Planck Institute, could help us to get a clearer picture of how this spectacular feature of a galaxy forms.
The galaxy, known as IC 342, rests some 10 million light years away and was scrutinised by the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) and the MPIfR’s 100-metre Effelsberg radio telescope in Germany. The combined efforts of the two facilities, which operate in radio wavelengths, show a huge, twisted magnetic loop coiled around the galaxy’s main spiral arm – and it’s thought that the magnetic field is squeezing so tightly that the flow of galactic gas is affected.
“Spiral arms can hardly be formed by gravitational forces alone,” says Rainer Beck from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, Germany. “This new view of IC 342 indicates that magnetic fields also play an important role in forming spiral arms.”
Getting such a close look at IC 342 has also picked out a bright central region that could host a black hole and of which is also prolifically producing new stars. In order to keep up the high rate of star production, Beck reasons that there must be a steady inflow of gas coming in from the galaxy’s outer regions. “The magnetic field lines at the inner part of the galaxy point toward the galaxy’s centre and would support an inward flow of gas,” he explains.
Beck and his team of astronomers mapped the structure of IC 342’s magnetic field by measuring the orientation, also known as the polarisation, of the radio waves spat out by the galaxy.
It was Beck, amongst other astronomers at the Max Planck Institute, who were the first to detect polarised radio emission in galaxies when they made observations of the Andromeda Galaxy (M31) in 1978.
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