Molecular Torus Surrounds Black Hole
Explanation:
Why do some black hole surroundings appear brighter than others?
In the centers of
active galaxies, supermassive
black holes at least
thousands of times the mass of our
Sun dominate.
Many, called
Seyfert Type I, are very bright in visible light.
Others, called
Seyfert Type II, are rather dim.
The difference might be caused by some
black holes accreting
much more matter than others.
Alternatively, the black holes in the center of
Seyfert
Type II galaxies might be obscured by a surrounding
torus.
To help choose between these competing hypotheses,
the nearby Seyfert II galaxy
NGC 4388 has been observed in
X-ray light recently by many recent Earth-orbiting
X-ray observatories, including
CGRO,
SIGMA,
BeppoSAX,
INTEGRAL,
Chandra, and
XMM-Newton.
Recent data
from INTEGRAL and XMM-Newton have
found that the X-ray flux in some X-ray colors varies rapidly,
while flux in other X-ray colors is quite steady.
The constant flux and apparent absorption of very
specific X-ray colors by cool
iron together
give evidence that
the central black hole in NGC 4388 is seen through a
thick torus composed of
molecular gas and dust.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
