Isolated neutron stars
Abstract
This chapter deals with X-ray emission from isolated neutron stars for which the energy for the observed X-rays is thought to originate from the rotation of the neutron star, or from an internal heat reservoir following formation. Rotation power can manifest itself as pulsed emission, or as nebular radiation produced by a relativistic wind of particles emitted by the neutron star. Residual heat of formation is observed as soft X-ray emission from young neutron stars. Such thermal radiation, however, can also be produced as a result of reheating from internal or external sources. Rotation-powered pulsed and nebular X-ray emission, as well as thermal emission, can often be observed in a single object simultaneously; this is both fascinating and annoying, as one invariably contaminates the study of the other. There are also a handful of neutron stars for which the origin of the observed X-ray emission is unclear but may be related to the above processes; we will discuss those as well.