ATLANTA — An international team of astrophysicists has discovered hundreds of mysterious structures at the center of the Milky Way galaxy.
These one-dimensional cosmic threads are hundreds of horizontal or radial filaments, thin, elongated bodies of luminous gas that potentially originated a few million years ago when outflow from Sagittarius A*, the Milky Way’s central supermassive black hole, interacted with surrounding materials, according to a study published Friday in The Astrophysical Journal Letters. The filaments are relatively short in length, each measuring 5 to 10 light years.
The findings come nearly 40 years after Farhad Yusef-Zadeh, the study’s lead author, and other researchers discovered another population of nearly 1,000 one-dimensional filaments, which are vertical and much larger, up to 150 light-years long each. , near the center of the galaxy. Yusef-Zadeh and collaborators also found hundreds more of paired and clustered vertical filaments in the same area in 2022, realizing that the filaments were likely related to Sagittarius A* activity rather than supernova explosions, as they had previously thought. The new study strengthens and builds on previous findings.
Finding the new population of structures that appear to point in the direction of the black hole came as a surprise, Yusef-Zadeh, a professor of physics and astronomy at Northwestern University’s Weinberg College of Arts and Sciences, said in a news release.
I was truly amazed when I saw these. We had to work hard to establish that we weren’t kidding ourselves, added Yusef-Zadeh, who is also a fellow at the Center for Interdisciplinary Exploration and Research in Astrophysics. We found that these filaments are not random but appear to be related to the outflow from our black hole. It is satisfying when order is found in the midst of a chaotic field of our galaxy’s core.
The discoveries of the black hole located about 26,000 light-years from Earth are very exciting and demonstrate just how beautiful the universe is, said Erika Hamden, an assistant professor of astronomy at the University of Arizona who was not involved in the study.
Sagittarius A* is the closest supermassive black hole to us, but it’s relatively quiet and therefore quite difficult to actually study, Hamden added. But this work provides evidence that it was recently emitting a lot of energy into space in the form of a jet and a conical outflow.
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The researchers found the structures by analyzing images produced by the South African Radio Astronomy Observatories’ MeerKAT telescope, which has 64 satellite dishes each 65 feet (nearly 20 meters) high and connected across 5 miles (about 8 kilometers) of a sparsely populated area. with minimal interference.
MeerKAT’s new observations were a game changer, said Yusef-Zadeh. It is really a technical achievement of radio astronomers.
Despite the similarities between the newly discovered strands and those identified in 1984, the authors of the new study don’t think the populations share exactly the same traits.
The vertical filaments lie perpendicular to the galactic plane, while the horizontal ones are parallel to the plane and point radially toward the black hole, according to the news release. The vertical filaments surround the Milky Way’s core, but the horizontal ones appear to widen to one side towards the black hole.
The distribution and alignment of the filaments can help show how the material has moved and distorted in the past, Hamden said.
Their behavior is also different: The horizontal filaments emit thermal radiation and material associated with molecular clouds partially or completely embedded in the outflow from the black hole, the authors wrote. Molecular clouds are made up of gas, dust and stars. The vertical filaments, on the other hand, are magnetic and hold the electrons of cosmic rays moving at nearly the speed of light.
The authors think studying the new filaments further could help them learn more about the rotation of black holes and the orientation of the accretion disk, Yusef-Zadeh said.
A black hole accretion disk is the thin, hot structure resulting from material from a nearby star being pulled in a circle around the black hole.
Follow-up is also needed to determine whether jet-driven outflow from the black hole, and thus more filaments, appear on either side of the black hole, Hamden said. A jet in this context is a beam of matter ejected from some astronomical object.
A black hole typically ejects jets symmetrically, so there should be a pair, Hamden added. One way to confirm that the (filament) structure is created by something like a jet is to find both sides of it.
This would add to the complex and active picture of our Milky Way, he said.
Yusef-Zadeh said he believes their work is never complete.
We always need to make new observations, he said, and continually challenge our ideas and strengthen our analysis.
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