The population of radio-quiet and thermally emitting isolated neutron stars. A comprehensive picture of neutron star evolution in the Galaxy

观测到的中子星数量主要是射电脉冲星。然而，近年来发现了各种孤立中子星(INSS)的观测现象，包括磁星、X射线暗淡孤立中子星(XDINS)和旋转射电瞬变(RRATS)。特别是，XDIN由附近的七个同质组组成，冷却的INS显示出独特的性质。虽然目前探测到的源数量较少，但特殊的INS亚群可能代表了银河系中子星的相当一部分，出于许多原因，它们非常重要。首先，对个别来源的调查可以极大地影响我们对重力和磁场极端条件下的物质物理的理解。其次，各个子群之间的关系有助于我们理解决定中子星现象学的主要性质。最后，随着新天体的发现，银河系中子星诞生和演化的全面图景将成为目标。我们建议研究银河系的中子星群，特别是XDINS，以刻画中子星的性质和演化状态，并了解这些特殊的子群是如何相互关联的，以及如何与大部分“正常”射电脉冲星群相关联的。为实现这些目标，将进一步研究特殊INS的现有样本，在更远的距离确定新的INS候选者，并利用现有和未来的X射线设施模拟银河系中热发射INS的产生、演化和可探测性。

The observed population of neutron stars is dominated by radio pulsars. In recent years, however, different observational manifestations of isolated neutron stars (INSs) have been discovered, which include magnetars, X-ray dim isolated neutron stars (XDINS) and rotating radio transients (RRATs). In particular, XDINS constitute a homogeneous group of seven nearby, cooling INSs displaying unique properties. While currently fewer in number of detected sources, the peculiar INS subgroups might represent a considerable fraction of the neutron stars in the Galaxy and are very important for a number of reasons. First, the investigation of individual sources can greatly impact our understanding of the physics of matter at extreme conditions of gravity and magnetic field. Second, the relations between the various subgroups help us to understand the main properties determining the neutron star phenomenology. Finally, as new objects are discovered, a comprehensive picture of neutron star birth and evolution in the Milky Way can be aimed for. We propose to investigate the Galactic population of neutron stars, especially focusing on XDINS, in order to characterise neutron star properties and evolutionary state, as well as to understand how the peculiar subgroups relate to each other and to the bulk of the “normal” radio pulsar population. These goals will be pursued by studying further the existing sample of peculiar INSs, by identifying new INS candidates at greater distances and by modeling the creation, evolution and detectability of thermally emitting INSs in the Milky Way with current and future X-ray facilities.