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No light comes from the black hole itself (excluding Hawking radiation, which is unimaginably weak from a supermassive black hole) but the region around the black hole, the accretion disk where material accumulates before shedding angular momentum and falling into the hole, can be spectacularly bright (because it can be heated to billions of degrees). The accretion disk and jet formation region can be brighter than all the stars in a galaxy. That's what a quasar is.

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