Figuring out the large-scale magnetic field structures in the Milky Way has actually been a major obstacle for numerous astronomers in the world for decades.Discovery of Magnetic ToroidsIn a new study released in The Astrophysical Journal on May 10, Dr. Jun Xu and Prof. Jinlin Han from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) have actually exposed big magnetic toroids in the halo of the Milky Way, which are essential for cosmic ray propagation and supply crucially restriction on the physical procedures in the interstellar medium and the origin of cosmic magnetic fields.Prof. In 1997, he found a striking anti-symmetry of the Faraday results of cosmic radio sources in the sky with regard to the collaborates of our Milky Way galaxy, which tells that the magnetic fields in the halo of the Milky Way have a toroidal field structure, with reversed magnetic field directions below and above the Galactic plane.Challenges in Measuring Magnetic FieldsHowever, to figure out the size of these toroids or the strength of their magnetic fields has actually been a tough task for astronomers for decades. All Faraday rotation measurement data in the past 30 years were gathered by Dr. Xu.Through data analysis, researchers discovered that the anti-symmetry of the Faraday rotation measurements triggered by the medium in the Galactic halo exists in all the sky, from the center to the anti-center of our Milky Way, which indicates that the toroidal magnetic fields of such a odd symmetry have a big size, existing in a radius range from 6000 light-years to 50,000 light-years from the center of the Milky Way.Conclusion and ImpactThis research study has substantially advanced our understanding of the Milky Ways physics and marks a turning point in research on cosmic magnetic fields.Reference: “The Huge Magnetic Toroids in the Milky Way Halo” by J. Xu and J. L. Han, 10 May 2024, The Astrophysical Journal.DOI: 10.3847/ 1538-4357/ ad3a61.
