Charged Layers in the Pulsar Wind express
A thin layer of oil on the surface of water breaks into separate droplets at the slightest disturbance. Something similar happens in the pulsar wind — a stream of particles ejected by a rapidly rotating neutron star. This stream also contains plasma layers, which can break apart into clumps — magnetic islands. But unlike oil, these layers carry an electric charge.
In the new study, scientists used computer simulations to find out how charge affects the tearing. Initially, the charged layer loses uniformity: fast oscillations, Bernstein waves, are born in the plasma (similar to ripples running along a taut string). These waves shuffle the charge, making its distribution patchy. However, this has little effect on the growth of the magnetic islands themselves: they only become slightly charged.
Another scenario involves rotating layers. If the layer is not just stretched but twisted, like a vortex in a drain, charge plays a more noticeable role. Under certain conditions, tearing accelerates: magnetic islands multiply faster than in the uncharged case. This resembles a notched sheet of paper that tears more easily if it has been crumpled beforehand. The results help understand how the energy of the pulsar wind is converted into radiation and high-energy particles.
Bernstein waves are named after physicist Ira Bernstein, who described them in 1958. They do not leave the plasma but are trapped inside it, like sound in a musical instrument.