Crab nebula's neutron star is pulsing with gamma rays

Crab nebula's neutron star is pulsing with gamma rays:

In 1054, a supernova went off in our galactic neighborhood and was recorded in a number of historical accounts. Today, the remnants of that blast form the spectacular Crab Nebula shown above. Buried within it is a rapidly rotating neutron star, which we can detect by its pulsed emissions. Now, researchers have used a rather unusual telescope—one that incorporates our own planet into the optics—to catch a glimpse of the pulsar using very high energy gamma rays.

The results are surprising: in contrast to expectations, the pulses are visible at energies of 100GeV and beyond, casting doubt on our current models for how pulsars work.

Peeking at pulsars

Stars of an appropriate mass—larger than the sun, but not big enough to form a black hole—leave behind a neutron star following their explosive ends. These stars start out spinning very rapidly and, in the process, sweep an intense magnetic field through the surrounding medium. The moving field accelerates charged particles, causing them to emit light at radio frequencies right up through gamma rays. Because of their rapid rotation, these light emissions come in the form of pulses that are only milliseconds apart, matching the neutron star's rapid rotation.