Mon Prof Augmenté
Hot Disk at a Galaxy Center
At the center of a galaxy, a supermassive black hole pulls gas into a swirling disk. The gas becomes so hot that it glows in X-rays, which is how astronomers detect the black hole.
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In the picture
- Dark central circle: the supermassive black hole at the galaxy’s core
- White-hot inner ring: gas heated to millions of degrees as it spirals inward
- Orange outer band: cooler gas still orbiting in the accretion disk
- Pale blue-white glow: X-ray light from the hottest inner gas
Examples
- A hidden electric heater can be found by the red glow of its hot coil.
- A doctor uses X-rays to see a bone even though the X-rays themselves are invisible.
Key takeaways
- Supermassive black holes sit at the centers of most large galaxies.
- Their hot accretion disks emit X-rays, letting astronomers detect them indirectly.
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