Views of the heart of the Milky Way captured by Atacama Large Millimeter/Submillimeter Array (ALMA) and the Chandra X-ray telescope.
(Image credit: X-ray: NASA/CXC/Northwestern Univ./M. Gorski; Radio: ESO/NAOJ/NRAO/ALMA; Image processing: NASA/CXC/SAO/K. Arcand and P. Edmonds. NASA/UMass/D.Wang et al.)
After searching for 50 years, astronomers have finally discovered evidence of powerful winds blowing from Sagittarius A* (Sgr A*), the supermassive black hole at the heart of our galaxy. The discovery represents a deepening of our understanding of the physics at play both around supermassive black holes and at the heart of the Milky Way.Scientists have long proposed that black holes produce energy as they consume matter that pushes material away from their vicinity, a process which has been dubbed "black hole winds." That even applies to Sgr A*, which exists on a diet of gas and dust so meager For a human, the equivalent would be consuming one grain of rice every million years.The problem is, scientists have been unable to collect evidence of black hole winds blowing through the heart of the Milky Way, resulting in a mystery that has persisted in astronomy for around half a century — that is, until now."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.'"Seeing black hole winds is far from a breezeScientists 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.”
