- Astronomers found clear evidence of a hot cosmic wind from Sagittarius A* black hole
- A large cone-shaped cavity near Sgr A indicates the wind swept away or heated cold gas
- ALMA and Chandra data revealed cold gas absence and hot gas X-ray emissions in this cavity
Astronomers have made a major discovery at the centre of the Milky Way galaxy. For the first time, they have found clear evidence that the supermassive black hole known as Sagittarius A (Sgr A) is blowing a hot cosmic wind, confirming a prediction that scientists have been investigating for more than 50 years, reported NASA.
The discovery is based on observations showing a large cone-shaped cavity near Sgr A. Researchers found that this structure appears to have been created by a powerful and energetic wind coming from the black hole.
A composite image released by scientists shows the evidence for this wind. The white dot at the centre marks Sgr A. Data from the Atacama Large Millimetre/Submillimeter Array (ALMA) radio telescopes in Chile is shown in orange and maps cold gas made up of carbon monoxide. X-ray data from NASA's Chandra X-ray Observatory is shown in blue.
Scientists observed that a large cone-shaped cavity, visible as an absence of cold gas in the ALMA data, is filled with hot gas that emits X-rays in the Chandra observations. Researchers believe that a hot wind from Sgr A either swept away the cold gas or heated it, creating the structure.
According to long-standing scientific theory, when a black hole feeds on gas, it should also release some material back into space in the form of winds or jets. However, the wind from the Milky Way's own central black hole had never been clearly detected.
Using several years of highly detailed ALMA observations, astronomers mapped cold gas located within just a few light-years of Sgr A. After carefully removing the bright radio emission from the black hole, they identified a giant cone-shaped hole in the cold gas. The structure points directly toward the black hole and is considered clear evidence of a large, hot and active wind being launched from Sgr A.
The findings have been described in a paper by Mark Gorski and Lena Murchikova of Northwestern University. The paper has been accepted for publication in The Astrophysical Journal Letters.
