Credit: M. Sako (Columbia)
X-raying the Warm Absorber
The centers of active galaxies are thought to host extremely massive black
holes. These central black holes, which can hold the equivalent of mass of
a million suns, produce very violent explosions of X-rays which make the
active galaxies bright and very variable. Apparently nature tries to
shield the mysteries of the central black holes from prying eyes by placing
a screen of absorbing material between us and the black hole. This
material, sometimes called the "warm absorber" itself produces
characteristic emission of radiation. It also absorbs the X-rays produced
by the central black hole, and this absorption effect can be used to study
both the nature of the absorber and the black hole itself. The XMM-Newton X-ray telescope has
provided a good look at the absorption of radiation produced by the warm
absorber in the quasar
IRAS 13349+2438. The graph above shows the X-ray spectrum produced by
the black hole in this quasar. At certain characteristic energies the
X-ray emission drops suddenly; these "absorption lines" are produced as
X-rays from the black hole are swallowed up by certain atoms (like carbon,
nitrogen, and iron) in the warm absorbing material between us and the black
hole.
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Page Author: Dr. Michael F.
Corcoran
Last modified April 4, 2002
