A pulsar is a rapidly spinning neutron star,
which is the small incredibly dense remnant
of much more massive star.
A teaspoon of matter from a neutron star weighs
as much as Mount Everest and the neutron star
is so compact That a ball about fifteen miles
across contains more matter than our sun.
Neutron stars spin between seven and forty
thousand times a minute and form with incredibly
strong magnetic fields.
Rapid spin and intense magnetic fields drive
powerful beams of electromagnetic radiation
including gamma rays.
As the pulsar rotates, these beams sweep the
sky like a lighthouse.
To a distant observer, the pulsar appears
to blink on and off.
Pulsars slow down as they age but some of
the oldest pulsars spin hundreds of times
a second.
Each of these millisecond pulsars orbits a
normal star.
Over time, the impact of gas pulled from the
normal star has spun the pulsar up to incredible
speeds.
This accretion may be the cause of their weaker
magnetic fields.
Despite this, these pulsars also emit gamma
rays.
Phil Plait: Gamma rays are the highest energy
form of light.
Dave Thompson: There's the light we see with
our eyes, but their lots of other types of
light.
Gamma rays are the most energetic form of
light, the most powerful.
Valerie Connaughton: Gamma rays are the part
of what we call the electromagnetic spectrum
which starts in radio, at very long wavelengths,
goes through optical, then through x-rays,
and then gamma rays are the very highest energy
form of that type of radiation.
Neil Gehrels: The reason that it's important
to look at the high-energy gamma rays is that
many objects, the most violent and some of
the most interesting objects in the universe
emit most of their light in this high-energy
gamma ray part.
Phil Plait: And the only thing that can generate
gamma rays are incredibly violent events,
incredibly energetic events.
And we're talking stars exploding and neutron
stars with really strong magnetic fields and
really exotic and strange objects like that.
Isabelle Grenier: It's like a Christmas tree
it's shining, and it's flaring and their are
eruptions every day.
Peter Michelson: Gamma-ray bursts being an
example of something that, for a brief instant
of time outshines the entire rest of the universe.
Chip Meegan: These are the biggest explosions
in the universe.
The Fermi Gamma-ray Space Telescope is a powerful
space observatory that opens a wide window
on the universe.
Gamma rays are the highest-energy form of
light, and the gamma-ray sky is spectacularly
different from the one we perceive with our
own eyes.
With a huge leap in all key capabilities,
Fermi is enabling scientists to observe some
of the universes most powerful phenomena,
including supermassive black holes, pulsars,
and gamma-ray bursts, which briefly outshine
whole galaxies.
Fermi has two instruments for observing gamma
rays.
It's Large Area Telescope, or LAT, maps gamma
rays over the entire sky every three hours
and is Fermi's main detector.
The other instrument is called the Gamma Ray
Burst Monitor or GBM.
It looks for spectacular flashes of gamma
rays from, among other things, the birth of
black holes far across the universe.
