Compact Binaries and the Origin of Millisecond Pulsars

天文学家观测到的旋转速度最快的中子星的旋转周期为毫秒，被称为毫秒脉冲星。这些恒星在银河系中大约有250颗是已知的，它们是现代天体物理学的重要实验室，研究领域从广义相对论到超新星研究。大多数都是通过从双星伴星中吸积物质来获得快速旋转的，这一过程被称为“脉冲星循环”。然而，这些系统中的大多数已经永久停止了吸积，并且有低质量的白矮星伴星，这使得研究脉冲星的循环过程变得不可能。密歇根州立大学的一个研究小组已经开发出一种方法，使用美国国家科学基金会支持的SOAR望远镜来发现仍在积极吸积的新脉冲星，这将使他们能够揭示毫秒脉冲星是如何形成的，并对中子星的本质有新的认识。该团队将通过观察美国宇航局费米伽马射线太空望远镜新发现的伽马射线源附近的变星，并测量它们的详细物理特性来实现这一目标。该团队将指导本科生进行天文学研究，重点是招募在科学领域代表性不足的群体的成员，并将校园天文台的公众观测与大学足球比赛联系起来。当中子星在双星系统中被旋转成毫秒脉冲星时，它为广义相对论提供了严格的测试，而质量最大的中子星可以为超新星爆炸的细节提供线索，并在密度超过原子核的情况下限制冷核物质的状态方程。计划中的工作将导致发现独特的中子星双星，阐明新型中子星双星的存在，为毫秒脉冲星演化模型提供信息，并追踪中子星的质量分布。这些双星将用多波长无线电、x射线和伽马射线数据进一步表征。

The fastest-spinning neutron stars observable by astronomers have rotation periods of milliseconds and are known as millisecond pulsars.  These stars, of which about 250 are known in the Milky Way Galaxy, are important laboratories for modern astrophysics in fields ranging from general relativity to the study of supernovae.  Most have acquired their brisk spins by accretion of matter from a binary companion, a process known as "pulsar recycling." However, most of these systems have permanently stopped accreting and have low-mass white dwarf stellar companions, making it impossible to study the pulsar recycling process.   A research team at Michigan State University has developed a method to use the NSF-supported SOAR telescope to discover new pulsars that are still actively accreting, which will allow them to uncover how millisecond pulsars are formed and find new insights into the nature of neutron stars.   The team will do this by observing variable stars near gamma-ray sources newly discovered by NASA's Fermi Gamma-Ray Space Telescope, and measuring their detailed physical properties.  The team will mentor undergraduate students in astronomy research, with an emphasis on recruiting members of groups underrepresented in science, and also link public observing at the campus observatory to university football games.When spun up as millisecond pulsars in binary systems, neutron stars offer stringent tests of general relativity, and the most massive neutron stars can give clues to the details of supernovae explosions and constrain the equation of state of cold nuclear matter at densities exceeding those of atomic nuclei. The planned work will lead to the discovery of unique neutron star binaries, clarify the existence of new classes of neutron star binaries, inform models for millisecond pulsar evolution, and trace the mass distribution of neutron stars.   These binaries will be further characterized with multi-wavelength radio, X-ray, and gamma-ray data.