PROBING A QUASAR'S HOME
Images taken by the Hubble Space Telescope have allowed astronomers to clearly
see the link between quasars and their companion galaxies. Some quasars, such
as the one in this two-panel image, have been caught in the act of merging or
colliding with their companion galaxies.
The image on the left reveals the huge, thin tidal arms of a galaxy associated
with the luminous quasar, which is 1.5 billion light-years from Earth. The
odd-shaped arms suggest an encounter between the quasar and a companion
galaxy. The thick bright line above the quasar is an edge-on background
In the right-hand panel, the same image is shown at a different contrast
level, which enables astronomers to peer closer into the galaxy's nucleus.
Only 11,000 light-years separate the quasar and the companion galaxy (located
just above the quasar). This galaxy is similar in size and brightness to the
Large Magellenic Cloud galaxy near our Milky Way. The galaxy is closer to the
quasar's center than our sun is to the center of our galaxy. The quasar and
galaxy are drawn together by strong gravitational forces. Eventually, the
galaxy will fall into the quasar's engine, the black hole. Black holes are
believed to power the compact, energetic quasars. The black hole will gobble
up this companion galaxy in no more than 10 million years.
The quasar in these images appears large, but actually, it is a compact, yet
powerful light source. The quasar is so bright that it created diffraction
spikes on these telescope images.
The images were taken with the Hubble Space Telescope's Wide Field and
Planetary Camera 2.
Credits: John Bahcall (Institute for Advanced Study, Princeton) and NASA