An international team of astrophysicists has discovered something completely new hidden in the center of the Milky Way galaxy. In the early 1980s, Farhad Youssef-Zadeh of Northwestern University discovered giant one-dimensional fibers suspended vertically near Sagittarius A*, the central supermassive black hole of our galaxy. Now Youssef-Zadeh and his collaborators have discovered a new population of filaments, but these filaments are much shorter and extend horizontally or radially and spread out like the spokes in a black hole wheel.

Although the two filament populations share many similarities, Youssef-Zadeh suggests they have different origins. Vertical lines stretch across the galaxy up to 150 light-years high, while horizontal lines look more like Morse code dots and lines, delineating only one side of Sagittarius A*.

The research will be published on Friday, June 2. Astrophysical Journal Letters .

“It was a surprise to suddenly discover a new population of structures that seem to point in the direction of the black hole,” said Youssef-Zadeh. “I really fainted when I saw it. It took a lot of work to make sure we weren’t fooling ourselves. And we found that these threads are not random, but seem to be related to the flow of our black hole. By studying them, we can learn more about the rotation of the black hole and the direction of the accretion disk. Finding order in the middle of the chaotic field at the core of our galaxy.” Beautiful.” Youssef-Zadeh, a radio astronomer, is a professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences and a fellow of CIERA.

A decade under construction

The new discovery may come as a surprise, but Youssef-Zadeh is no stranger to unraveling the mysteries at the center of our galaxy, 25,000 light-years from Earth. The latest work builds on forty years of his research. After detecting vertical filaments for the first time with Mark Morris and Don Chance in 1984, Youssef-Zadeh, together with Ian Heywood and colleagues, discovered two giant radio-emitting bubbles near Sagittarius A*. Then, in 2022, Youssef-Zadeh (in collaboration with Heywood, Richard Arendt, and Mark Wardle) discovered in a series of publications about 1,000 vertical fibers that appear in pairs and clusters, often equidistant or close together, like harp strings.

Youssef-Zadeh attributes the new stream of discovery to advanced radio astronomy technology, specifically the South African Radio Astronomy Observatory’s (SARAO) MeerKAT telescope. To pinpoint the filaments, Youssef-Zadeh’s team used background removal and noise smoothing techniques from MeerKAT images to isolate the filaments from surrounding structures.

“The new MeerKAT observations are game-changing,” he said. “The development of technology and the time devoted to observations have given us new insights. This is truly a technical achievement of radio astronomers.”

horizontal and vertical

After decades of studying vertical strands, Youssef-Zadeh was shocked to discover horizontal strands, which he estimates are about 6 million years old. “We’ve always thought about vertical filaments and their origins,” he said. “I’m used to them being vertical. I never thought there might be others on the plane.’

Although both populations consist of one-dimensional filaments that can be observed with radio waves and appear to be related to activity in the galactic centre, the similarities end there.

Vertical threads are perpendicular to the galactic plane; the horizontal fibers are parallel to the plane but point radially towards the center of the galaxy where the black hole is located. Vertical fibers are magnetic and relative; horizontal teeth emit thermal radiation. Vertical filaments contain particles moving at speeds close to the speed of light; horizontal filaments appear to accelerate thermal material in the molecular cloud.

There are several hundred vertical threads and only a few hundred horizontal threads. And vertical fibers, reaching 150 light-years in height, significantly exceed the dimensions of horizontal fibers with a length of 5 to 10 light-years. Vertical fibers also adorn the area around the galactic core; horizontal filaments appear to extend in only one direction, pointing to a black hole. Source