Galactic Center filaments are large radio-emitting[3] filament-shaped structures found in the Galactic Center of the Milky Way.[4] Their cause is unknown.[4] Both vertical and horizontal filaments exist, running vertically (perpendicular to the galactic plane) and horizontally (parallel to the galactic plane) away from the Galactic Center, respectively.[4][5] Vertical filaments possess strong magnetic fields[6] and emit synchrotron radiation: radiation emitted by particles moved at near-lightspeed through a magnetic field.[4] Although theories have been proposed, the source of these particles is unknown.[4][7] Horizontal filaments appear to emit thermal radiation, accelerating thermal material in a molecular cloud.[3] They have been proposed to be caused by the outflow from Sagitarius A*, the Milky Way's central black hole, impacting vertical filaments and H II regions of ionized gas around hot stars.[4]
While the vertical filaments can reach 150 light years in length, the horizontal filaments are much shorter, usually around 5 to 10 light years long.[5] A few hundred horizontal filaments exist (figure given as of 2023[update]), far fewer than the number of vertical filaments.[5] Vertical filaments were discovered in 1984 by Farhad Yusef-Zadeh, Mark Morris, and Don Chance;[citation needed] horizontal filaments were discovered in 2023 by Yusef-Zadeh, Ian Heywood and collaborators.[4]
Vertical filaments are often found in pairs and clusters, often stacked equally spaced side by side similar to the strings of a harp.[6] As of 2022[update], it was unknown why they formed in clusters or in a regularly spaced manner.[7]