How Pulsars Work

What is The Source of the Emitted Radiation? Ordinary stars emit light simply because they are hot… But that is NOT the source of the light from the neutron star! How, then, do they produce the light we see?

Remember Two Special Properties: The secret that allows us to understand the pulsars: their rapid rotation, plus their enormously strong magnetic fields.

Further Insights: a Relevant Digression How do modern ‘particle physicists’ learn about the innermost workings of atoms? -- the bits and pieces that make them up?

Modern Particle Physics To understand a clock, smash it to bits -- and study the pieces that pop out!

We Do This to Atoms! Using Cyclotrons (‘Atom-smashers’)

Just Keep ‘Pushing’

After the Collisions The tracks and trails reveal the particle properties (charges, masses, energies, etc)

Synchronized Pushes: Easy! …as noted by Galileo

But Remember Einstein Relativity theory reveals that there is an increasing inertia of particles as they get accelerated towards the speed of light. Our repeated‘pushes’do not yield the acceleration you expect. No matter how much energy we put in, the speed never quite gets to “c”. One consequence is that we can get out of sync: our pushes don’t come at quite the right moment.

We Can Compensate: Synchronize the Pushes Synchro-cyclotrons --- ‘synchrotrons’ for short

Fermilab (near Chicago)

What Happens There

CERN (Conseil européen pour la recherche nucléaire)

The Large Hadron Collider http://www.youtube.com/watch?v=FLrEghnKncA

The ATLAS Detector…

…and the Debris…

…and its Interpretation!

The Higgs Boson!

Synchrotron Radiation [A by-product]

Useful in Research

The Canadian Light Source [based at the University of Saskatchewan] Visit https://www.youtube.com/watch?v=ArhZGRu33H4 to learn more about synchrotrons (and also to understand the scientific research which your government supports).

Reconsider the Earth In the Earth’s magnetic field, charged particles loop back and forth, North and South. Does this create synchrotron radiation?

No! The charged particles are low-energy, and moving much too slowly. (The auroras are created in a different way! When the charged particles bombard the atmospheric gases, they make them glow like ‘Neon lamps’.)

But Now Add Rapid Rotation to Ultra-Strong Magnetic Fields!

The Oblique Rotator Model Three essential ingredients: Strong magnetic field Rapid rotation Magnetic field axis and rotation axis different Question: What has the tip of the magnetic axis got to do with it?

Lighthouse Analogy If the beam of light was lined up with the rotation axis, it would always point the same direction in space. We would not see any ‘on-off’ behaviour!

Pulsars Can’t Last Forever They are rotating very fast, with periods that range from milliseconds to tens of seconds. [Millisecond pulsars are a special class: they have been ‘spun up’ (made to spin even faster) through later interactions with a binary companion star.] But energy is being lost, so they must (and do) slow down. This is readily observed.

Here We See Steady Slowdown – Plus a ‘Glitch’

The Explanation? How can a neutron star abruptly speed up in its rotation? The answer: Starquakes! The material is readjusting itself in response to the slowing rotation rate: the neutron star shrinks just a little.

Analogy, Closer to Home… An Indian Ocean earthquake at Christmas 2005 caused a tsunami that killed ~300,000 people The earthquake decreased the length of day by 2.68 microseconds. That is, the quake caused the Earth to spin ever so slightly faster... The Earth's oblateness (flattening on the top and bulging at the equator) decreased by a small amount, about one part in 10 billion. The position of the "mean North pole" was shifted east by about 2.5 centimeters (1 inch)...

The Internal Structure of a Neutron Star [don’t worry about the details shown!]