WESTERN AUSTRALIA — A global research team led by the CSIRO mapped cosmic magnetic fields by measuring light from nearly 4 million galaxies as it traveled through intergalactic space. This dataset, now open-access for global researchers, covers an area five times larger than previous cosmic magnetic field mapping efforts.
The Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope array collected the data for this map. ASKAP is located at the Inyarrimanha Ilgari Bundara observatory in Western Australia. Previous mapping projects had excluded observations of the southern sky. The dataset is named SPICE_RACS, which stands for Spectra and Polarisation In Cutouts of Extragalactic Sources from the Rapid ASKAP Continuum Survey, and the Astronomical Society of Australia published it.
The map represents magnetic fields pointing toward Earth with red and fields pointing away with blue. Stars, galaxies, and intergalactic space contain naturally occurring magnetic fields. Gravity and electromagnetism are the primary physical forces that govern the movement of matter in space, with Earth's own magnetic field generated by the movement of molten metals within its core.
CSIRO astronomer and astrophysicist Dr. Alec Thomson said the map helps answer questions about the origin and evolution of magnetic fields in the universe. He said, "We still don't actually know how magnetic fields started in the universe, or how they've changed across time since the big bang. And so this type of map helps us start to answer those questions and be able to look at the details of the magnetic universe."
Chief scientist of the Square Kilometre Array observatory, Prof. Naomi McClure-Griffiths, noted the expansion of available data. "For the past 20 years we have been working with essentially the same dataset." McClure-Griffiths said. "Now, we can finally answer some big questions with a much better picture of the universe's magnetic structures."
Prof. Lisa Harvey-Smith, an astrophysicist at UNSW Sydney, indicated the potential for future research. Harvey-Smith said, "The result of creating the map is not the end product. The end product will be over the next few years with scientists dipping in and doing their own studies of particular star-forming regions or particular galaxies. And there'll be so many discoveries that flow on from this map."