Observations of Sagittarius A* by NASA’s James Webb Space Telescope
The James Webb Space Telescope (JWST), launched in 2021, has been observing the supermassive black hole at the center of the Milky Way galaxy, known as Sagittarius A* or Sgr A*. These observations provide the best view yet of the chaotic events occurring around this black hole.
Key Findings
- JWST recorded a steady flickering of light from the accretion disk surrounding Sgr A*, punctuated by occasional bright flares.
- The region around Sgr A* is described as bubbling with activity rather than being in a steady state.
- Astrophysicists observed one to three large flares over any 24-hour period, with smaller bursts occurring in between.
The Accretion Disk
- The accretion disk comprises swirling hot gas that gets chaotic and compressed as it approaches the black hole due to extreme gravity.
- The flickering light emanates from material close to the event horizon, beyond which nothing can escape the black hole's pull.
- Approximately 90% of the accretion disk's material falls into the black hole, while the rest is ejected into space.
Research Insights
- Astrophysicist Farhad Yusef-Zadeh describes the region as filled with turbulence, where blobs of gas collide and are compressed by strong magnetic fields.
- These mechanisms are compared to solar flares but occur in a vastly different environment at higher energy levels.
Significance of the Observations
- The observations provide insights into how black holes interact with their surroundings.
- They reveal that Sgr A* is less active compared to some other supermassive black holes at the centers of other galaxies.
- The findings were based on 48 hours of data collected over a year, offering a more continuous view of Sgr A* activity.
Technological Advancements
- Previously, astronomers could only manage a few hours of observations using ground-based telescopes or about 45 minutes with the Hubble Space Telescope.
- JWST's Near-Infrared Camera (NIRCam) provides advanced sensitivity, allowing observations at two different infrared wavelengths.
- Howard Bushouse notes that the sensitivity and extended observation times of JWST allow detection of more frequent and less bright flares across various wavelengths.