2 November 1999

Edited by Emma Sanders

New study of distant quasars

Subaru, Japan’s new 8.3 m telescope on Mauna Kea in Hawaii (CERN Courier March), is being used for a new study of gravitationally lensed quasars. A luminosity of more than 100 galaxies is emitted from a quasar, which has a volume no larger than our solar system.

Einstein’s theory of General Relativity shows that the gravitational pull from massive objects is able to deflect rays of light like a lens. For example, astronomers see four bright images of the quasar PG1115+080 more than 10 billion light years away. The four lensed images appear around a much nearer, massive galaxy in the centre, which acts as the lens. The relative brightness and position of the individual images gives a measure of how rapidly the universe is expanding.

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