The Milky Way's Gamma-Ray Halo
Explanation:
Our Milky Way galaxy appears to be surrounded by a halo of gamma rays.
Gamma rays are the most energetic form of
electromagnetic radiation, with
more than a hundred thousand times the energy of visible light,
but known gamma-ray sources
don't account for the diffuse distribution of this high-energy glow.
This surprising result
is based on data
from the EGRET instrument onboard
the Compton Gamma Ray Observatory.
In this false color
all-sky image centered on
the Milky Way, the
brown and green regions indicate brighter, known sources of gamma-rays.
The galactic center and plane clearly standout as do some
distant galaxies seen near the top and bottom of the picture.
The dim, blue regions above and
below the plane correspond to our Galaxy's unexpected gamma-ray halo.
What causes the halo?
Future gamma-ray telescopes
could solve this mystery.
However, the excitement has already inspired tantalizing
speculation about the solution including;
collisions of low energy photons with
high-energy cosmic rays,
high energy electrons accelerated by a previous burst of
Milky Way
star formation,
and exotic interacting particles which make up
Dark Matter.
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.
