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Quasi-stellar objects (QSOs or Quasars) are bizarre objects discovered with enormous cosmological redshifts.

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Bright radio sources

  • Quasars were discovered as very bright sources in the radio spectrum.
  • When an optical telescope was used to see if there was a visible object at the source of the radio waves, all that was found was what looked like a very faint star.
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Extremely bright

  • Quasars have very large cosmological redshifts (up to 7!) which means they are very far away indeed.
  • To be observed at these distances in both visible and radio telescopes implies that they are very much more luminous than the entire Milky Way.
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Supermassive black holes

  • It is now believed that quasars are formed from supermassive black holes up to 800 million times more massive than the sun.
  • The radiation emitted comes from the gas that rapidly spirals into the black hole.

Jump to other topics

1Measurements & Errors

2Particles & Radiation


4Mechanics & Materials


6Further Mechanics & Thermal Physics (A2 only)

7Fields & Their Consequences (A2 only)

8Nuclear Physics (A2 only)

9Option: Astrophysics (A2 only)

10Option: Medical Physics (A2 only)

11Option: Engineering Physics (A2 only)

12Option: Turning Points in Physics (A2 only)

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