Our local black hole creates an ‘awesome moment’
Astronomers have discovered a new set of whiskers on the black hole at the center of our Milky Way galaxy: filaments of radio energy several light years long, streaming outward along the galactic plane.
According to Farhad Yusef-Zadeh of Northwestern University, the streaks may be the fading remnants of explosive outbursts from the black hole, Sagittarius A*, which contains the mass of 4 million suns.
Dr. Yusef-Zadeh led a team of radio astronomers that studied Sagittarius A* with the MeerKAT telescope, the sprawling array of antennas at South Africa’s Radio Astronomy Observatory. They published their results on June 2 in The Astrophysical Journal Letters.
The discovery adds a new dimension to the electrical complexity of the Milky Way. In its structure, the galaxy resembles a sunny-side up egg, with a spherical, bright center surrounded by a flat disk of stars, gas, and dust.
Dr. Yusef-Zadeh, a dedicated explorer of the galaxy’s heart, and his colleagues had already discovered radiofilaments, thin magnetic energy tubes 150 light-years long, perpendicular to the galactic plane like the pickets of a fence.
The new filaments are shorter – a few light years long – and they run in a different direction, parallel to the galactic plane rather than through it. “It was a surprise to suddenly find a new population of structures that seem to be pointing in the direction of the black hole,” Yusef-Zadeh said in a press release from Northwestern University. “I was really stunned when I saw this one.”
He added in an email: “The filaments display nicely once you know what you are looking for. It was an awe-inspiring moment for us to realize that these filaments were pointing to the black hole.”
The geometry of the new streaks suggests the black hole rotates on an axis parallel to the plane, Dr. Yusef-Zadeh to it. The energy is squeezed out of the poles like toothpaste out of a tube. Astronomers still don’t know what the perpendicular vertical filaments are, he said.
Future observations with the Event Horizon Telescope, the widespread network of Earthbound observatories that produced the first image of Sagittarius A* in 2022, should shed more light on the black hole’s behavior and orientation, said Dr. Yusef-Zahed. He added: “It is gratifying to find order in the middle of a chaotic field of our galaxy’s core.”