Quark matter in neutron stars

Neutron stars, spotted as pulsars by radio telescopes and x-ray satellites, contain matter up to ten times denser than atomic nuclei, thus providing a high-pressure environment in which numerous subatomic particle processes are expected to compete with each other and novel phases of matter - like the quark-gluon plasma being sought at the most powerful terrestrial particle colliders - could exist. This article aims at exploring the possible existence of quark matter inside neutron stars and pointing out the fingerprints by means of which this novel phase of matter could register itself in the observed pulsar data. The detection of such matter in neutron stars would help to clarify how quark matter behaves, and give a boost to theories about the early universe as well as laboratory searches for the production of quark matter in heavy-ion colliders. (author)