Observations from the X-Ray Imaging and Spectroscopy Mission (XRISM) have provided direct evidence that outflows from supermassive black holes can drive gas out of galaxies, effectively suppressing star formation. University of Michigan researchers analyzed data from NGC 4151, an active galactic nucleus located about 50 million light-years away.
Key Findings
XRISM's high spectral resolution allowed detection of fine structures in accretion disk winds.
- Winds in NGC 4151 reach velocities sufficient to expel star-forming gas from the galaxy.
- The winds are likely launched via magnetocentrifugal driving, a mechanism similar to solar flares.
- Fast outflows were strongest when X-rays were hard but faint, occurring about 10,000 seconds after X-ray flares.
Methods
Researcher Xin Xiang developed a novel metric called "cindicity" (color intensity index) to correlate X-ray hardness and brightness with the presence of outflows. The analysis covered hundreds of days of observations to identify flare events and subsequent wind activity.
Implications
- The results strongly support theoretical models where black hole feedback regulates galaxy growth by removing the gas needed to form new stars.
- The method may enable astronomers to predict outflow states in other active galactic nuclei based solely on X-ray color and intensity.
Attribution
The findings were reported by Xin Xiang (doctoral student, University of Michigan) at the 248th AAS meeting, in collaboration with Jon Miller (University of Michigan professor of astronomy). XRISM is a collaborative mission between JAXA, NASA, and ESA.