Scientists have made a groundbreaking discovery in the Milky Way’s halo: enormous magnetic rings.
This finding is significant because the origin and behavior of cosmic magnetic fields have puzzled astronomers for years.
Understanding these fields is a priority for major radio telescopes worldwide, such as the Square Kilometer Array (SKA) currently being built.
In a recent study published in The Astrophysical Journal, Dr. Xu Jun and Prof. Han Jinlin from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) revealed these vast magnetic rings.
These rings are crucial for understanding how cosmic rays travel and provide valuable insights into the interstellar medium’s physical processes and the origin of cosmic magnetic fields.
Prof. Han, a prominent scientist in this field, has been studying the magnetic fields along the Milky Way’s spiral arms for years.
In 1997, he discovered a surprising pattern in the Faraday effects of cosmic radio sources, which suggested that the Milky Way’s halo had a toroidal (ring-like) magnetic field structure.
This pattern showed reversed magnetic field directions above and below the galactic plane.
However, measuring the size and strength of these magnetic rings has been challenging. Some astronomers thought the anti-symmetry observed might be caused by the interstellar medium near the sun, as nearby pulsars and radio-emission objects showed similar Faraday effects.
To determine if these magnetic fields existed far beyond the sun’s vicinity, Prof. Han proposed a new approach.
By measuring the Faraday rotation from pulsars near the sun using data from the Five-hundred Aperture Spherical radio Telescope (FAST) and subtracting this from the background cosmic sources’ measurements, they could isolate the effect of the galactic halo.
Dr. Xu collected all Faraday rotation data from the past 30 years.
Their analysis showed that the anti-symmetry caused by the galactic halo’s medium was present across the entire sky, from the Milky Way’s center to its outer edges.
This implies that these toroidal magnetic fields are enormous, stretching from 6,000 to 50,000 light-years from the Milky Way’s center.
This discovery offers a new understanding of the Milky Way’s physics and marks a significant milestone in the study of cosmic magnetic fields.
Source: Chinese Academy of Sciences.
