Starship Asterisk*

Synchrotron Christmas tree in the galactic center. Credit: T. Thomas (AIP)/MeerKat

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Researchers at the Leibniz Institute for Astrophysics in Potsdam (AIP), and the Max Planck Institute for Astrophysics in Garching (MPA), have investigated galactic radio objects that adopt shapes such as Christmas trees and harps. With the help of these objects, the old question of how cosmic radiation propagates could be answered.

The inner region of our Milky Way galaxy is characterised by large amounts of warm gas, cosmic-rays and enhanced radio emission. “Astronomers have been observing planar radio-emitting magnetised structures in the galactic centre for almost twenty years. Recent observations with the MeerKAT telescope in South Africa show that these are organised into groups of almost parallel filaments, that span over a length of several light years,” reports Timon Thomas from the AIP, the leading author of the study. “The filaments are seemingly sorted by their length, so that they look like the strings of a harp.” Hence, researchers from Potsdam and Garching called these objects radio synchrotron harps. Synchrotron is the name of the mechanism that generates the radio emission. It arises when charged particles like electrons are accelerated in magnetic fields.

“The observed structures are created when massive stars or pulsars fly through an ordered magnetic field and discharge cosmic ray particles along their path into these magnetic fields,” explains co-author Christoph Pfrommer from AIP. “The particles propagate along the magnetic field lines, usually transverse to the stellar orbit, causing the magnetic fields in the radio regime to light up and appear like the strings of a harp.” ...

• arXiv.org > astro-ph > arXiv:1912.08491 > 18 Dec 2019

• Nature 573(7773):235 (12 Sep 2019) DOI: 10.1038/s41586-019-1532-5
• arXiv.org > astro-ph > arXiv:1909.05534 > 12 Sep 2019