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Scientists Find Wind Blowing From Our Milky Way's Black Hole
After 50 years of searching, astronomers say they have finally found evidence of a long-sought "wind" blowing from Sagittarius A*, the supermassive black hole at the center of the Milky Way. "Unless a black hole exists in a perfect vacuum, it must blow a wind somehow. And there is no perfect vacuum in the universe," team co-leader and Northwestern University researcher Mark Gorski said in a statement. "With new observations, this is the first time we've had a clean enough view to see the wind's imprint. We looked at the data and said, 'There it is. There is the thing that everybody's been looking for for 50 years.'" Space.com reports: Scientists have been aware for some time that feeding black holes launch powerful outflows of material around them, including jets and winds. Winds are caused when matter falling to the black hole is accelerated to near light-speed, generating pressure that pushes infalling material away. That has been seen with ravenously feeding black holes before, but not the barely feeding Sgr A*. Its sparse consumption of material and the fact it is obscured by the plane of the Milky Way from our vantage point have made tracing this wind difficult.
Gorski's Northwestern colleague and team co-leader Lena Murchikova pointed out that the scientists were the first to detect molecular gas very close to Sgr A* feeding the supermassive black hole. That makes Sgr A* reassuringly like other supermassive black holes. "The wind is not powerful, and its direction probably wanders with time. It shows that our black hole is not unique, and our place in the universe is not unique," Murchikova added. "To observe our own black hole, we have to look through the plane of our galaxy. That means we have to peer through gas, dust and ionized structures, and you can't really see through all of that easily."
While the team's results confirm that Sgr A* is extremely quiet compared to the supermassive black holes that sit in bright, turbulent regions of other galaxies called active galactic nuclei (AGN), this black hole wind is no slouch. In fact, the scientists think that it has been raging for around 20,000 years. "The majority of other galaxies spend most of their lives in a state where they are not particularly active," Murchikova said. "But we can only see them when they are in a fireworks stage. It is very attractive to study black holes when they are in the fireworks stage, but that's not actually their dominant state. "Sgr A* finally gives us a window into the life of a black hole in this quiet state."
The team's research was published in The Astrophysical Journal Letters.
Read more of this story at Slashdot.
