Soft x-ray emission from isolated neutron stars

Full text: Investigation of emission from the surfaces of isolated neutron stars (NS) provides, with the aid of advanced theoretical models of thermal emission, a unique opportunity to infer the NS surface temperatures, magnetic fields, chemical composition and, ultimately, NS masses and radii. This information, supplemented with the model equations of state and NS cooling models, can lead to understanding the fundamental properties of the superdense matter in the NS interiors. As the surface temperatures of isolated NSs observable are predicted (and found) to be within a range from about a half to a few million degrees, soft x-rays (0.1-10 keV) are the key energy band for detecting and studying the NS thermal radiation. The first possibility for this investigation was opened about 30 years ago with the launch of the x-ray observatories Einstein and EXOSAT. A significant contribution to this study was provided by ROSAT in 1990's, whose instrumental sensitivity peaked in the soft x-ray band. The outstanding capabilities of the currently operating observatories, Chandra and XMM-Newton, have greatly increased the potential to observe and analyze thermal radiation from isolated NSs. In this presentation an overview is given on the most important aspects of the theoretical modeling of the NS thermal emission, as well as results from Chandra and XMM-Newton observations of isolated NSs of various types. (author)