Possible explanation for radio bursts: Meet the “blitzar”

Aren't you a bit heavy for that magnetic field?

NASA

Yesterday, we brought word of a new kind of mysterious astronomic event, one that created a single, energetic burst of radio waves, but otherwise left no apparent trace. Although there are a lot of things we know about that might cause something similar, none of them are likely to occur with the right frequency or at the right energy to produce the radio bursts. While doing research for that story, however, I came across a paper that describes something we've never seen before, but could hypothetically exist: the blitzar, caused when a neutron star catastrophically collapses into a black hole.

If you're a fan of supernovae—and, really, if you're not, what's wrong with you?—you'd know that they tend to leave extraordinarily compact and dense bodies behind. If they're below a critical mass, quantum effects balance out the pull of gravity by keeping neutrons from occupying the same quantum state. Once the mass gets high enough—technically, above the "Tolman–Oppenheimer–Volkoff limit"—gravity can overwhelm the quantum effects, and collapse both matter and space into a black hole. Typically, this is presented as an either/or: a body is on one side of the mass limit or the other, and its identity is set accordingly.

But that turns out to only be true if there are no other forces acting on the body in question. And, in the real world (or even the somewhat surreal world of the forces interacting in a supernova remnant), there are usually a number of other forces in action. One of these is the fact that the neutron star, when it forms, inherits a lot of the rotational energy of the parent star. Since its radius and mass are tiny in comparison to the star, this means that the neutron star starts out rotating, often extremely rapidly. This rotation could potentially keep a neutron star that's heavier than the Tolman–Oppenheimer–Volkoff limit from collapsing to form a black hole. The authors of the paper describing these bodies, Heino Falcke and Luciano Rezzolla, call them supramassive rotating neutron stars, or SURONs.