Galactic Center filament
Radio-emitting filaments of unknown origin in the Milky Way's center.
In the Milky Way's center lie large, filament-shaped structures that emit radio waves, known as Galactic Center filaments. Scientists do not know what causes them. These filaments come in two orientations: vertical ones run perpendicular to the galactic plane, while horizontal ones run parallel to it. Vertical filaments have strong magnetic fields and give off synchrotron radiation—light produced when particles move at nearly the speed of light through a magnetic field. Horizontal filaments seem to emit thermal radiation. Farhad Yusef-Zadeh, Mark Morris, and Don Chance first spotted vertical filaments in 1984; Yusef-Zadeh, Ian Heywood, and their team discovered horizontal filaments in 2023.
- discovered
- 1984 (vertical), 2023 (horizontal)
- type
- Astronomical structures
- location
- Galactic Center of the Milky Way
- length
- Up to 150 light-years (vertical); 5–10 light-years (horizontal)
- known_for
- Radio-emitting filaments of unknown origin
- discoverers
- Farhad Yusef-Zadeh, Mark Morris, Don Chance (vertical); Yusef-Zadeh, Ian Heywood, collaborators (horizontal)
Lore & Background
Vertical Galactic Center filaments were first discovered unexpectedly in a 1984 publication by Yusef-Zadeh et al. Initially considered possible artifacts, they were confirmed after being observed at multiple wavelengths by multiple groups. Because the earliest filaments detected were all vertical, oriented perpendicular to the galactic plane, early theories suggested they may have been related to the Milky Way's magnetic field. By 1996, a number of theories had been proposed, including the idea that they were cosmic strings, which faced difficulties such as the lack of observed oscillation and apparent splitting of some filaments.
Reader's Guide
Galactic Center filaments are significant because they represent a persistent mystery in astrophysics: their cause remains unknown despite decades of study. Vertical filaments, discovered in 1984, are now known to emit synchrotron radiation from particles moving at near-lightspeed through strong magnetic fields, but the source of those particles is unknown. Horizontal filaments, discovered in 2023, appear to emit thermal radiation and have been proposed to be caused by outflow from Sagittarius A* impacting vertical filaments and H II regions. The discovery of about ten times more filaments in 2022 using the MeerKAT telescope allowed statistical study. Vertical filaments are often found in pairs and clusters, stacked equally spaced like harp strings, but as of 2022 it was unknown why they formed that way. Analyses of galaxy rotation curves have also suggested similar vertical gravitating filaments at the centers of other galaxies, indicating the phenomenon may be widespread.
Did You Know?
- Vertical filaments can reach 150 light-years in length, while horizontal filaments are usually 5 to 10 light-years long.
- As of 2023, a few hundred horizontal filaments were known, far fewer than the number of vertical filaments.
- Vertical filaments were discovered in 1984 by Farhad Yusef-Zadeh, Mark Morris, and Don Chance.
- Horizontal filaments were discovered in 2023 after Yusef-Zadeh noticed many filaments pointing radially away from the Galactic Center.
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