A Galactic Cloud of Antimatter
Explanation:
The center of our Milky Way Galaxy is full of surprises.
Its latest spectacular is
a mysterious cloud glowing in gamma rays produced
by annihilating antimatter particles!
Star Trek fans are all too familiar with the consequences of mixing
matter (electrons) and antimatter (positrons) -
the particles
catastrophically annihilate
converting their masses to energy according to Einstein's famous
E=mc
2.
Positron/electron annihilation energy is emitted
as gamma rays with
photon energies of 511,000 electron volts.
Searching for these high energy photons,
the OSSE instrument onboard NASA's orbiting
Compton Gamma Ray Observatory has
recently produced this map of the
Galactic Center (GC) region. As anticipated, it shows
annihilation gamma rays
as a bright spot at the GC
with fainter horizontal emission from the galactic plane.
Astoundingly, it also reveals a large and unexpected cloud
of annihilation radiation, probably about 4,000 light years across,
extending nearly 3,500 light years above the GC.
What could have created this cloud?
Associated with no previously known object,
it seems to imply that a
fountain of antimatter positrons streams from the GC.
Present guesses about the source of the positrons include
the violent and exotic environments surrounding starbirth,
neutron star collisions, and black holes at the GC.
Are there other such clouds in our Galaxy?
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.
