X-ray vision

摘要

Pulsars that only emit X-rays, once considered "anomalous", now officially outnumber those that emit radio waves. This is leading astronomers to rethink their ideas about what happens after a typical dying star explodes as a supernova. A supernova explosion occurs when a star runs out of nuclear fuel and shrinks catastrophically under its own gravity. The result is a super-dense neutron star about the size of Mount Everest. Current theories of how these stars behave predict that they should all act as radio pulsars, sweeping a narrow beam of radio waves around the sky like a lighthouse a hundred times a second. So why didn't radio searches find more pulsars in supernova remnants?