Theory of Radiative Transfer in Neutron Star Atmospheres and Its Applications

Before the first neutron star was discovered in 1967 as a radio pulsar¹ by Jocelyn Bell [22] it had been predicted that neutron stars can be powerful sources of thermal X-ray emission, having surface temperatures of about one million Kelvin [11, 78]. This prediction and the discovery of the first pulsar became one of many motivations for further developing X-ray astronomy at the end of the 1950s. Observational study of thermal radiation from neutron stars began in 1978 with the launch of the Einstein observatory which detected X-ray emission in the 0.2—4 keV range from a number of neutron stars and neutron star candidates. The ROSAT mission which was sensitive in the 0.1—2.4 keV range marks the beginning of the “decade of space science”, which in the 1990s provided many important results on observing X-ray emission from neutron stars. By extending the energy range up to 10 keV ASCA and BeppoSAX added important information on the pulsar emission in the harder band pass whereas EUVE and HST allowed to study neutron stars in the very soft 0.07—0.2 keV and optical/UV bands. More details on results from observations of neutron stars can be found in the Chaps. 6—8. New excellent observational data on neutron stars collected with two currently operating powerful X-ray observatories, Chandra and XMM-Newton (both launched in 1999), provide a breakthrough in studying emission properties of these enigmatic objects.