NRAO: Giant Magnetic Ropes in a Galaxy's Halo

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NRAO: Giant Magnetic Ropes in a Galaxy's Halo

Post by bystander » Wed Nov 27, 2019 11:40 pm

Giant Magnetic Ropes in a Galaxy's Halo
National Radio Astronomy Observatory | 2019 Nov 26
This image of the “Whale Galaxy” (NGC 4631), made with the National Science Foundation’s Karl G. Jansky Very Large Array (VLA), reveals hair-like filaments of the galaxy’s magnetic field protruding above and below the galaxy’s disk.

The spiral galaxy is seen edge-on, with its disk of stars shown in pink. The filaments, shown in green and blue, extend beyond the disk into the galaxy’s extended halo. Green indicates filaments with their magnetic field pointing roughly toward us and blue with the field pointing away. This phenomenon, with the field alternating in direction, has never before been seen in the halo of a galaxy. ...

An international team of astronomers who are part of a project called the Continuum HAlos in Nearby Galaxies — an EVLA Survey (CHANG-ES), led by Judith Irwin of Queen’s University in Ontario, said the image indicates a large-scale, coherent magnetic field that is generated by dynamo action within the galaxy and spirals far outward in the form of giant magnetic ropes perpendicular to the disk. ...

The image was made by combining data from multiple observations with the VLA’s giant dish antennas arranged in different configurations to show both large structures and finer details within the galaxy. The naturally-emitted radio waves from the galaxy were analyzed to reveal the magnetic fields, including their directions.

The scientists said the techniques used to determine the direction of the magnetic field lines, illustrated by this image, now can be used on this and other galaxies to answer important questions about whether coherent magnetic fields are common in galactic halos and what their shapes are. ...

Giant Magnetic Ropes in the Outskirts of a Spiral Galaxy
Max Planck Institute for Radio Astronomy | 2019 Nov 26

CHANG-ES XV: Large-Scale Magnetic Field Reversals in the Radio Halo of NGC 4631 ~ Silvia Carolina Mora-Partiarroyo et al Evolving Galactic Dynamos and Fits to the Reversing Rotation Measures in the Halo of NGC 4631 ~ Alex Woodfinden et al
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