A Mystery in Gamma Rays
Credit & Copyright: N. Gehrels, D. Macomb, D. Bertsch, D. Thompson, R. Hartman
(GSFC),
EGRET,
NASA
Explanation:
Gamma
rays are the most energetic form of light, packing a million
or more times the energy of visible light photons.
What if you could
see gamma rays?
If you could, the familiar
skyscape of steady stars would
be replaced by some of the
most bizarre objects
known
to modern
astrophysics -- and
some which are
unknown.
When the
EGRET instrument on the orbiting
Compton Gamma-ray Observatory surveyed
the sky in the 1990s, it cataloged 271
celestial sources of high-energy gamma-rays.
These sources are very different from the powerful
gamma-ray bursters
that flash and fade rapidly from view, and
researchers identified some
with exotic
black holes,
neutron stars, and distant
flaring galaxies.
But 170 of the cataloged sources, shown
in the above
all-sky map, remain unidentified.
Many sources in this gamma-ray mystery map likely
belong to the already known classes of gamma-ray emitters and are simply
obscured or too faint to be otherwise positively identified.
However, astronomers
recently called attention to the ribbon
of sources winding through the plane of the
galaxy, projected here along the middle of the map, which
may represent a large unknown class of galactic gamma-ray emitters.
In any event, the unidentified sources could remain a mystery
until the planned launch of the more sensitive
Gamma-ray Large
Area Space Telescope in 2005.
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.
