Astrophysicists astonished by enigmatic structures uncovered in the Milky Wayas they detect numerous enigmatic structures known as cosmic threads, which appear as elongated filaments of luminous gas. These one-dimensional threads, measuring 5 to 10 light-years in length, are either horizontal or radial in orientation.
The researchers propose that these threads likely formed millions of years ago when the outflow from Sagittarius A*, the supermassive black hole at the galactic center, interacted with the surrounding materials.
This groundbreaking study, published in The Astrophysical Journal Letters, builds upon previous research by Farhad Yusef-Zadeh and his team. Nearly four decades ago, they discovered another set of approximately 1,000 vertical cosmic filaments near the galaxy's center, with each filament spanning up to 150 light-years in length.
In 2022, Yusef-Zadeh and his collaborators identified additional paired and clustered vertical filaments in the same region, realizing that these structures were likely linked to the activity of Sagittarius A*, rather than originating from supernova explosions as previously believed. The recent study not only confirms their earlier findings but also expands our understanding of these intriguing cosmic filaments.
In a surprising development, Farhad Yusef-Zadeh, a professor of physics and astronomy at Northwestern University's Weinberg College of Arts and Sciences, expressed his astonishment upon discovering a new population of structures that appear to be aligned towards the supermassive black hole. Yusef-Zadeh made this statement in a press release, highlighting the unexpected nature of this finding.
According to Yusef-Zadeh, who's also a member of the Center for Interdisciplinary Exploration and Research in Astrophysics:
I was actually stunned when I saw these. We had to do a lot of work to establish that we weren't fooling ourselves. We found that these filaments are not random but appear to be tied to the outflow of our black hole. … It is satisfying when one finds order in (the) middle of a chaotic field of the nucleus of our galaxy.- Farhad Yusef-Zadeh, a professor of physics and astronomy at Northwestern University's Weinberg College of Arts and Sciences
Erika Hamden, an assistant professor of astronomy at the University of Arizona, who was not part of the study, expressed her enthusiasm for the findings regarding the black hole situated approximately 26,000 light-years away from Earth. Hamden described the results as "really exciting" and emphasized how they showcase the exquisite beauty of the universe.
Sagittarius A* "is the closest supermassive black hole to us, but it's relatively quiet and therefore somewhat difficult to really study," Hamden added. "But this work provides evidence that it was recently ejecting quite a lot of energy into space in the form of a jet and conical outflow."
A representation of the Milky Way
By analyzing images captured by the MeerKAT telescope, operated by the South African Radio Astronomy Observatory, the research team was able to identify the cosmic structures. The MeerKAT telescope consists of 64 satellite dishes, each towering at a height of approximately 65 feet (around 20 meters).
These dishes are strategically positioned across a 5-mile (approximately 8-kilometer) expanse in a sparsely populated region, ensuring minimal interference in their observations. The utilization of the MeerKAT telescope played a crucial role in enabling the researchers to make these significant findings.
"The new MeerKAT observations have been a game changer," Yusef-Zadeh said. "It's really a technical achievement from radio astronomers."
Although there are resemblances between the recently discovered filaments and those identified in 1984, the authors of the new study believe that the two populations exhibit distinct characteristics. The vertical filaments, positioned perpendicular to the galactic plane, envelop the nucleus of the Milky Way.
On the other hand, the horizontal filaments align parallel to the plane and extend radially in the direction of the black hole. Notably, the horizontal filaments seem to disperse asymmetrically towards one side in proximity to the black hole. These contrasting features differentiate the vertical and horizontal filaments, as highlighted in the news release.
According to Hamden,
The distribution and alignment of the filaments can help show how the material has moved and distorted in the past.- Erika Hamden, an assistant professor of astronomy at the University of Arizona
In addition to their distinct characteristics, the behavior of the vertical and horizontal filaments also sets them apart. The horizontal filaments were found to emit thermal radiation and contain material associated with molecular clouds, which may be partially or fully embedded in the outflow from the black hole.
These molecular clouds consist of gas, dust, and stars. On the other hand, the vertical filaments exhibit magnetic properties and house cosmic ray electrons that move at speeds approaching the velocity of light.
The researchers believe that further investigation of these newly discovered filaments could provide valuable insights into the spin and orientation of the black hole's accretion disk. An accretion disk is a thin and hot structure that forms when material from a neighboring star is drawn into a circular orbit around the black hole. Farhad Yusef-Zadeh expressed the potential significance of studying these filaments in unraveling more about the black hole's characteristics and its surrounding accretion disk.
Erika Hamden highlights the importance of further investigation to determine whether the jet-driven outflow from the black hole, and consequently more filaments, are present on both sides of the black hole. In this context, a jet refers to a concentrated stream of matter expelled from certain astronomical objects.
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, active picture of our own Milky Way," she said.
Yusef-Zadeh said he believes their work is never complete.
We always need to make new observations and continually challenge our ideas and tighten up our analysis.