RX J0911.4+0551: A gravitationally
lensed distant quasar.
Caption: Chandra’s high
resolution image reveals a four-way mirage image (A1, A2, A3 and
B) of a quasar known as RX J0911.4+0551. Quasars are extremely
distant galaxies with luminous cores thought to be powered by
supermassive black holes. A single "point source" image of a
quasar may appear as a mirage of images when the gravity of an
intervening massive galaxy forces light rays to bend and take
different paths to reach us. These variations in the quasar
– which are much more rapid at X-ray than at optical
wavelengths – show up at different times in the mirage.
With future observations, it may be possible to measure the time
lag in the variations from one image to the next and estimate
the difference in distance traveled. This information could then
be used to estimate the distance to the quasar and the expansion
rate of the universe.
CXC operated for
NASA by the Smithsonian Astrophysical