A black hole’s elusive wind, Pg2

Key Highlights:

• Astronomers have found definitive evidence of a hot gas wind emanating from Sagittarius A*, the supermassive black hole at the center of the Milky Way.
• The discovery was made by researchers from Northwestern University using five years of data from the ALMA telescope in Chile.
• This wind creates a cone-shaped clearing, at least 3.2 light-years long, in the dense molecular gas surrounding the black hole.
• The wind plays a crucial role in regulating star formation, preventing an excessive number of stars from forming and thus influencing galaxy evolution.

Detailed Insights:

• The existence of a wind from Sagittarius A* had been suspected for over 50 years but lacked definitive evidence until this study.
• The ALMA telescope, located in the Atacama Desert of Chile, provided unprecedentedly detailed observations of cold gas, particularly carbon monoxide.
• The observed cone-shaped cavity opens at a 45-degree angle, indicating the direction of the expelled material.
• The wind actively pushes away cold gas that would otherwise fall into the black hole, thereby controlling the available material for star birth.
• The mechanism involves gas swirling around the black hole, heating to millions of degrees due to friction and gravitational pressure, and becoming plasma.
• This superheated gas is highly energetic; just 1 gram can release enough energy to push away 100 kilograms of nearby gas.
• The wind is estimated to have been active for at least 20,000 years, influencing the galactic environment.

Scientific/Technical Concepts Involved:

• Sagittarius A (Sgr A): The supermassive black hole located at the galactic center of the Milky Way galaxy.
• ALMA Telescope: The Atacama Large Millimeter/submillimeter Array, a powerful astronomical observatory in Chile used to study cold objects in the universe.
• Black Hole Wind: Outflows of hot, energetic gas expelled from the vicinity of a black hole, impacting its surrounding environment.
• Star Formation: The process by which dense regions within molecular clouds collapse under gravity to form new stars.