The university writes:
The team viewed the “Whirlpool Galaxy” Messier 51 (M51), about 30 million light years away, with the Low Frequency Array (LOFAR) radio telescope in the frequency range 115-175 MHz, just above the normal commercial FM radio frequency band of 88-108 MHz. These results are the first LOFAR observations of a nearby galaxy.
LOFAR consists of 38 stations in the Netherlands, six stations in Germany and one station each in the UK, France and Sweden. The signals from all stations are then combined in a powerful computing cluster located at the University of Groningen in the Netherlands.
The research, which was led by David Mulcahy from the university’s Astronomy Group, is published in the journal Astronomy & Astrophysics. It was conducted for his PhD work at the Max Planck Institute for Radio Astronomy.
“Low-frequency radio waves are important as they carry information about electrons of relatively low energies that are able to propagate further away from their places of origin in the star-forming spiral arms and are able to illuminate the magnetic fields in the outer parts of galaxies,” said David Mulcahy. “We need to know whether magnetic fields are expelled from galaxies and what their strength is out there.”
“This beautiful image, coupled with the important scientific result it represents, illustrates the fantastic advances that can be made at low radio frequencies with the LOFAR telescope,” added co-author Dr Anna Scaife from the University of Southampton. “Unravelling the mysteries of magnetic fields is crucial to understanding how our Universe works. For too long, many of the big questions about magnetic fields have simply been untestable and this new era of radio astronomy is very exciting.”
According to Southampton radio astronomy shows two important components of galaxies that are invisible to optical telescopes: cosmic ray electrons and magnetic fields.
The image shows a map of the whirlpool galaxy M51 produced by the LOFAR radio telescope, showing the electrons and magnetic fields in the spiral arms and extended disc of M51.