Dark matter may slow pulsars’ spin

New Scientist : Observations have revealed that many pulsars—the superdense, rapidly rotating neutron stars left following a star as it goes nova—have slowing rotations. Chris Kouvaris of the University of Southern Denmark and Maria Ángeles Pérez-García at the University of Salamanca in Spain propose that some of the slowdown is caused by the form of dark matter known as WIMPs, weakly interacting massive particles. WIMPs have a slight electric charge, which causes them to become trapped by pulsars’ magnetic fields. Once enough charge has accumulated, it is released along the magnetic field’s poles as an electric current. The interaction between the current and the magnetic field would slow the pulsar’s spin. Kouvaris and Pérez-García say that the theory can be tested by comparing pulsars at different distances from galactic centers. The pulsars closer to larger densities of dark matter would probably have faster slowdown rates.