Explanation:
Scanning the entire sky in gamma-rays,
photons with over 50 million
times the energy of visible light, the Fermi mission's Large Area
Telescope (LAT) explores the high-energy universe.
This all-sky map
constructed from 3 months of LAT observations
(August 4 to October 30, 2008)
represents a deeper, better-resolved view of the
gamma-ray sky than any previous space mission.
What shines
in Fermi's gamma-ray sky?
A new paper describes
the 205 brightest gamma-ray sources, but this map
highlights a Fermi "top ten" list of five sources
within, and five sources that lie beyond our
Milky Way Galaxy.
Within our galaxy: the Sun traces a faint arc across the map
between the observation dates, LSI +61 303 is an
X-ray binary star about
6,500 light-years away,
PSR J1836+5925 is a type of
pulsar
(spinning neutron star) that
is only seen to
pulse at gamma-ray energies, and
47 Tuc is
a globular star cluster some 15,000 light-years away.
A fifth galactic source (unidentified), just above the center
of the galactic plane, is intriguing because it is a variable
source and has no clear counterpart at other wavelengths.
Beyond our galaxy:
NGC 1275 is a large galaxy at
the heart of
the Perseus galaxy cluster some 233 million light-years away,
while 3C 454.3, PKS 1502+106, and PKS 0727-115 are active galaxies
billions of light-years distant.
Another unidentified source, seen below the galactic plane, is
likely beyond the boundaries of the Milky Way.
Its nature remains a mystery.
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