A half-century mystery solved
Astrophysicists at Northwestern University have finally found evidence of a wind blowing from Sagittarius A* (Sgr A*), the Milky Way's central supermassive black hole. The discovery, published in The Astrophysical Journal Letters, resolves a mystery that has puzzled astronomers for over 50 years. Theoretical physics predicted that all actively feeding black holes must produce winds or jets, but no one could find Sgr A*'s outflow until now.
How they found it
The team used five years of deep observations from the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile to construct the sharpest image ever of cold molecular gas near Sgr A*. After applying a calibration method to filter out the black hole's bright radio signals, the resulting image was 100 times deeper and 80 times sharper than previous maps. It revealed a vast, cone-shaped cavity nearly one parsec long and 45 degrees wide, devoid of cold gas — unmistakably carved by hot wind from the black hole.
Exceptional evidence
To confirm their findings, the researchers cross-referenced with X-ray data from NASA's Chandra Observatory, which showed bright X-ray emissions in the exact same region. "When you find something that no one has seen before, the first thought is not 'we made a discovery' — it's 'what's wrong with my analysis?" said co-lead researcher Elena Murchikova. The wind has been active for at least 20,000 years, and the discovery confirms Sgr A* is in a relatively quiet phase, offering a rare window into black hole behavior during non-eruptive periods.