One of the fun aspects of astrophysics is that much of it involves phenomena which you cannot exactly study from up close, with the supermassive black hole (SMBH) at the center of this galaxy – called Sagittarius A* (Sgr A) – being a great example. Although it’s been predicted since 1971 that black holes like Sgr A radiate energy which then pushes away nearby matter to create something akin to solar wind, this had so far not been proven. Now astronomers have discovered evidence for this emanating from Sgr A*.
Using five years worth of observations made with the Atacama Large Millimeter/Submillimeter Array (ALMA) and correlating it with other observations, a Southern Lobe of movement was identified, along with evidence for a Northern Lobe. Unlike a star where you are dealing with relatively massive quantities of matter being hurled into space, in the case of a very quiet SMBH like Sqr A* you are talking about occasional small wisps of gas of which a fraction gets turned into the radiation that then exerts pressure on the remaining gas.
It is speculated to be exactly this quiescent nature of Sgr A* that makes it so difficult to find evidence of SMBH wind, though one could also argue that having a well-fed SMBH whose event horizon rapidly expands would be fascinating from an astrophysics perspective, but less exciting for any nearby inhabited planets.