The speed of the most violent wind in space has been measured

For the first time, astronomers have succeeded in directly measuring the speed of ultra-hot gas erupting from the center of nearby galaxy M82, which is experiencing explosive star formation activity. As a result of analyzing data collected through the Resolve equipment of the

“Before XRISM, we didn’t have the ability to measure speeds to test this hypothesis,” said Dr. Erin Boettcher of the University of Maryland and NASA’s Goddard Space Flight Center, who led the study.

Why the M82 galaxy is important

M82, also known as the 'Cigar Galaxy', is located in the constellation Ursa Major, about 12 million light-years away from Earth. This galaxy is classified as a 'starburst galaxy', with a rate of star formation relative to its size that is about 10 times faster than that of our Galaxy. In particular, M82's cold wind extends up to 40,000 light-years and emits a huge amount of gas and dust, and several space telescopes, including NASA's Chandra, Webb, and Hubble, have intensively studied this phenomenon.

The key significance of this study is that it demonstrated the link between star formation activity and large-scale gas outflow with measured data. The researchers measured the speed of the wind by analyzing X-ray signals emitted from ultra-hot iron at the center of the galaxy. As a result of checking the temperature using the X-ray emission of elements including iron, it met the predicted value of about 25 million degrees Celsius.

Starburst galaxy research continued for over 30 years

Systematic research on M82 began in earnest with the development of X-ray astronomy in the 1990s. In the 2000s, the Chandra However, the actual speed of the hot wind could not be directly measured due to technical limitations.

XRISM's resolve equipment, which began full operation in 2024, has the high resolution and sensitivity to solve this difficult problem. This is a method of calculating the moving speed of gas by analyzing the degree of expansion of iron's spectral line using the Doppler effect. XRISM is an international mission led by JAXA and cooperated with NASA and the European Space Agency (ESA), and the Resolve equipment was jointly developed by NASA and JAXA.

Future outlook [AI analysis]

This study is likely to spark a new debate about the role of cosmic rays. Previous theories have assumed that cosmic rays, which are high-speed charged particles, may be the main pressure source of the galactic wind, but the results of this measurement show that heat and speed alone are enough to drive the cold wind.

However, there remains another mystery revealed by the researchers. The center of M82 is calculated to release gas equivalent to 7 solar masses every year, but at the measured wind speed, it can only push out gas equivalent to 4 solar masses per year. This suggests the possibility that additional gas outflow mechanisms exist.

In the future, comparative studies with other starburst galaxies are expected to be conducted through continued observations by XRISM, which is expected to advance the understanding of galaxy evolution and material circulation. The results of this study were published in Nature on March 25.