Explanation:
Where's the pulsar?
Previously, the nebula
CTA 1 showed
an expanding supernova remnant, a
jet, and a point source expected to be a
pulsar -- a
rotating neutron star producing pulses at radio energies.
But no radio pulses were detected.
Now NASA's recently deployed
Fermi Space Telescope has solved the mystery with some of its
initial observations indicating that the point source is pulsing at
gamma-ray energies.
The strange source is the first of a class that might be
dubbed "dark pulsars", rotating
neutron stars
that appear to pulse only in high-energy radiations.
Such pulsars
might not be detectable in
radio
or visible light if they emit those radiations into a narrow
beam not seen from Earth.
If true, our Galaxy might have more pulsars left for
Fermi to discover.
Studying the gamma-ray properties of
pulsars gives
valuable clues to physics of the emission regions on neutron stars.
In this graphic,
the pulsar's position is indicated in the wider
CTA 1
supernova remnant.
An artist's illustration of the pulsar beaming at gamma-ray energies
is shown in the inset.
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