New Research Reveals Milky Way's Magnetic Field is Far More Complex Than Understood
A research project led by UBC Okanagan (UBCO) has provided international scientists with the most detailed view to date of the Milky Way's magnetic field, revealing it to be significantly more complex than previously understood.
The Milky Way's magnetic field is significantly more complex than previously understood.
Pioneering Radio Astronomy at DRAO
Dr. Alex Hill, an Assistant Professor at UBCO's Irving K. Barber Faculty of Science, specializes in radio astronomy. His team at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton utilized data from the DRAO 15-meter telescope. This effort resulted in the first broadband map of Faraday rotation, a phenomenon crucial for tracking magnetic fields across the northern sky.
Introducing the DRAGONS Dataset
The collected data, known as the Dominion Radio Astrophysical Observatory GMIMS of the northern sky (DRAGONS) dataset, was led by former UBCO postdoctoral researcher Dr. Anna Ordog. It records polarized radio emissions across various frequencies, enabling astronomers to observe magnetic structures previously undetectable. This initiative is part of the larger Global Magneto-Ionic Medium Survey (GMIMS), spearheaded by Dr. Tom Landecker.
"The new dataset allows for observation of polarized emissions from within the galaxy, showing extensive structure in the magnetic field."
Dr. Anna Ordog added that "DRAGONS is the first to demonstrate this level of complexity over such vast spatial scales across the entire northern sky."
From Theory to Modern Feasibility
This work builds upon a 1966 theoretical concept that proposed measuring the three-dimensional structure of the Milky Way's magnetic field using polarized radio waves at multiple frequencies. Modern broadband telescopes, including the DRAO 15m telescope, have now made this research feasible.
The 15m telescope, initially a prototype for the larger SKA radio telescope, was first used scientifically for this project. Dr. Ordog directed the setup of DRAGONS, with support from UBCO and University of Calgary students, as well as DRAO engineers. The telescope's ability to rapidly scan allowed for the mapping of the polarized sky in six months. UBCO students were involved in analyzing "first light" signals, developing algorithms for interference detection, and assessing data quality.
Key Discoveries and Their Significance
Published in The Astrophysical Journal Supplement Series, the study tracks the twisting of polarized radio waves as they traverse the galaxy, indicating the strength, structure, and direction of magnetic fields. The survey shows that over half the sky contains intricate magnetic structures rather than uniform fields.
The survey shows that over half the sky contains intricate magnetic structures rather than uniform fields.
Dr. Landecker noted that the prevalence of "Faraday complex" regions was a significant discovery. He explained that DRAGONS functions like a compass, illustrating the organization of matter and magnetic fields within the galaxy and how the magnetic field interacts with galactic features such as supernova remnants and spiral arms.
Dr. Hill emphasized the importance of magnetic fields in shaping star formation and galaxy evolution. He highlighted that while previous measurements of the Milky Way's magnetic field were averaged and simplified, understanding its complex nature is crucial for comprehending the universe's operations and origins.
"Understanding its complex nature is crucial for comprehending the universe's operations and origins."
A Canadian Contribution to Global Astronomy
DRAGONS data has already been used in studies, including research on a large-scale reversal in the galactic magnetic field, led by University of Calgary doctoral student Rebecca Booth and published in The Astrophysical Journal. Dr. Ordog concluded that DRAGONS is part of a new generation of radio surveys designed to map the Milky Way's three-dimensional magnetic field structure in interstellar space, representing a significant Canadian contribution to global astronomy.