An investigation into the enigmatic filaments suspended in space near the center of the Milky Way has unveiled an entirely new population of these structures. These newly discovered filaments align along the galactic plane and point towards the galactic center, revealing intriguing insights about our galaxy's core. According to astrophysicist Farhad Yusef-Zadeh from Northwestern University, these magnetized strands are likely remnants of an outflow from the supermassive black hole Sagittarius A* (Sgr A*) interacting with surrounding gas millions of years ago.
Although Sgr A* is presently relatively quiet, these filaments suggest recent activity in the center of our galaxy on cosmic timescales. Their discovery also implies that the galactic center, already known to be wild and dynamic, harbors more fascinating secrets waiting to be uncovered. Yusef-Zadeh expressed surprise at finding a new population of structures that appear to be aligned with the black hole, stating, "I was actually stunned when I saw these."
The discovery of the filaments holds significant implications. By studying these structures, researchers can gain insights into the spin of the black hole and the orientation of its accretion disk. It demonstrates the presence of order amidst the chaos within the nucleus of our galaxy. The vertical filaments, which were discovered by Yusef-Zadeh and his colleagues in the 1980s, were approximately 1,000 long, magnetized structures resembling harp strings. They may have been caused by winds emanating from an active supermassive black hole or turbulence in the intergalactic medium influenced by the motion of galaxies.
The new population of filaments was detected using data collected by the MeerKAT radio telescope in South Africa. During the data analysis process, while enhancing the visibility of the vertical filaments, the researchers unexpectedly identified a different population of filaments aligned horizontally along the galactic plane. These newly discovered structures, referred to as "harp strings," are shorter in length, measuring around 5 to 10 light-years. Unlike the vertical filaments, they emit thermal radiation.
The horizontal filaments exhibit a radial arrangement on one side of the galactic center, pointing back towards Sgr A*. In contrast, the vertical filaments are arranged in parallel around the galactic center. This radial arrangement is believed to be linked to the orientation of Sgr A* and a radial outflow generated by astrophysical jets originating from the vicinity of the black hole during active accretion. The researchers suggest that these radial dashes result from ram pressure caused by the jet-driven outflow from Sgr A*, and their analysis indicates that this activity occurred approximately 6 million years ago.
The presence of these filaments and other features such as giant bubbles extending above and below the galactic plane suggest that Sgr A* has recently ejected material through powerful astrophysical jets. However, the full history and dynamics of the Milky Way's center remain elusive, as new structures continue to emerge with the advancement of detection technologies.
Yusef-Zadeh emphasized the ongoing nature of their work, stating that new observations and analysis are crucial to continually challenge ideas and refine our understanding of the galactic core. The study detailing these findings was published in the journal Nature.