A neutron star is the collapsed core of a massive star, squeezed to the size of a city. In its heart, matter is packed so densely that atoms cease to exist, and protons and neutrons dissolve into a sea of quarks. If such matter is threaded by a magnetic field and its particles possess chirality (meaning they do not coincide with their mirror image, like left and right hands), then a wave of a special kind can run through it — a chiral magnetic wave.
This wave makes the star tremble — much like an earthquake makes a bell ring. But instead of seismic stations, the oscillations are detected via gravitational waves — ripples in spacetime that reach our detectors. Analyzing such "stellar tremors" can reveal what goes on inside a neutron star, where no telescope can peer.
Moreover, the authors found that electromagnetic fields in such a medium decay in an unusual way. Normally, waves in a plasma are damped by the Landau effect — particles drain their energy, like a crowd absorbing sound. Here, however, "dynamic screening" kicks in: the medium rearranges itself so quickly that the field cannot propagate. This can be compared to shouting in a room where the walls move in and muffle the sound before it reaches your ears.
This mechanism is important for understanding how compact stars behave during catastrophic events — for instance, when two neutron stars merge. Such events are already being detected via gravitational waves, and the new calculations will help more accurately decipher the signals arriving from the depths of space.
A neutron star the size of a city can weigh twice as much as the Sun — a teaspoon of its material weighs as much as Mount Everest.
In Greg Bear's novel "The Forge of God," neutron stars are inhabited by intelligent quark life, and their oscillations serve as a means of communication.