[Music] Narrator: A pulsar is the
crushed core of an exploded star. Theorists have been
trying to understand the details of how pulsars work ever since they were discovered
in 1967 -- especially how they emit precisely
timed pulses at radio to gamma-ray energies.
Now, new computer simulations are providing surprising insights.
A pulsar contains some of the strongest magnetic fields known
and can spin thousands of times a second. That means it's a
powerful dynamo, generating an electric field so strong
particles are ripped out of the surface and accelerated into space.
New computer simulations clearly show these incredible movements for the
first time. Most of these particles are electrons and their
antimatter counterparts, positrons. In these simulations,
their colors get lighter as they attain higher energies.
Electrons tend to race outward from the magnetic poles.
Positrons mostly flow out at lower latitudes along a relatively thin structure
called the current sheet. Ultimately, these
outflows lead to the formation of a powerful wind that extends far from
the pulsar. Magnetic field lines
and the particles moving with them, sweep back and extend outward as the
pulsar spins. Their rotational speed rises with greater distance,
but there's a wall created by the ultimate speed limit --
the speed of light. Astronomers call this the light cylinder.
Matter can't travel at the speed of light, so something has to give
before the particles get this far. Just before reaching
the light cylinder, these simulations show that a population of medium-energy
electrons scatter wildly -- sometimes even back toward the pulsar.
Some speed up, others slow. Most
eventually slip past the light cylinder and head out into space.
The simulations also show that a small percentage of positrons
likely hold the secret to a pulsar's gamma-ray emission.
Some of these particles become boosted to tremendous energies at points within
the current sheet where magnetic field lines meet. These simulations
bring scientists one step closer to understanding the incredible physics
of pulsars, something that has kept theorists busy for decades.
[Music]
[These visualizations use data from simulations by Brambilla et al., 2018]
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