Formation of neutron star / black hole binaries and their merger rate in the local Universe

预期的引力波探测将为宇宙打开一扇新的窗口，并补充我们从光子和中微子中获得的天体物理源的知识。先进的LIGO（激光干涉仪引力波天文台）探测器，连同它的欧洲姐妹探测器VIRGO和德国探测器GEO 600，将于2014年投入使用，并于2015年达到全灵敏度。对于高频引力波（10hz - 10khz）的瞬态爆发探测来说，最有希望的候选来源是合并的中子星（NS）和黑洞（BH）。这些致密的天体是在紧密的双星中形成的，由于引力波的持续发射，它们经历了螺旋式的融合，直到它们最终在一个剧烈的瞬态事件中合并——可能导致短暂的伽马射线爆发。该项目的主要目的是利用我们对恒星和双星演化的最新知识，从理论上计算出本地宇宙中这种NS/BH合并的速率。这些结果将与即将到来的LIGO探测率进行比较，这将使我们能够更好地约束关键双星相互作用背后的输入物理，如质量和角动量损失，共同包层，裸氦星的演化，大质量双星中快速恒星旋转的作用，最后，传递给新生的NS和BH的动量。该项目的第二个目标是更好地理解和量化围绕NS或BH运行的银河系循环射电脉冲星的形成、位置、性质和寿命。虽然我们知道有9颗射电脉冲星绕着另一个NS运行，但我们仍然没有探测到绕黑洞运行的射电脉冲星。通过这个项目，我们希望获得关于这些系统的理论知识，这将增加在未来无线电调查中成功的机会。当一个旧的脉冲星在一个紧密的双星系统中通过吸积伴星的质量和角动量而旋转到一个高的自旋频率时，就形成了一个循环脉冲星。这种质量传递过程的许多方面以及所涉及的吸积物理学还没有得到很好的理解，但在将射电脉冲星循环到高自旋速率和低b场的过程中起着至关重要的作用，这使得它们在接下来的数十亿年里都可以被探测到。因此，这项研究的第三个结果是更好地了解高质量x射线双星的演变，这再次可以与观测相冲突。为了模拟紧密双星的种群，需要大量双星系统样本的演化——从零年龄主序列开始，通过质量传递和超新星爆炸——以预测围绕NS和BH轨道运行的可观测射电脉冲星的数量，以及高级LIGO对合并的探测率。为了实现这些目标，我们利用先进的种群合成技术和蒙特卡罗模拟，首次探索了大质量双星演化的新方面。

The expected detection of gravitational waves will open a new window to the Universe and compliment our knowledge of astrophysical sources obtained from photons and neutrinos. The advanced LIGO (Laser Interferometer Gravitational-Wave Observatory) detector, together with its European sister VIRGO and the German detector GEO 600, will be operational in 2014 and reach full sensitivity in 2015. The most promising candidate sources for transient burst detections of high-frequency gravitational waves (10 Hz - 10 kHz) are merging neutron stars (NS) and black holes (BH). These compact objects are formed in tight binaries and undergo spiral-in due to continuous emission of gravitational waves until they finally merge in a violent transient event - possibly leading to a short gamma-ray burst. The main aim of this project is to calculate theoretically the rate of such merging NS/BH in the local Universe using our best up-to-date knowledge of stellar and binary evolution. These results will be compared to the upcoming LIGO detection rates which will enable us to better constrain the input physics behind key binary stellar interactions such as mass and angular momentum loss, common envelopes, evolution of naked helium stars, the role of rapid stellar rotation in massive binaries and, finally, the momentum kick imparted to newborn NS and BH. A second aim of this project is to better understand - and to quantify - the formation, the location, the properties and the lifetimes of Galactic recycled radio pulsars orbiting NS or BH. Whereas we know of 9 radio pulsars orbiting another NS we still have no detections of a radio pulsar orbiting a BH. With this project we hope to gain theoretical knowledge about such systems which will enhance the chance of success in future radio surveys. A recycled pulsar is formed when an old NS is spun up to a high spin frequency via accretion of mass and angular momentum from a companion star in a close binary system. Many aspects of this mass-transfer process and the accretion physics involved are not well understood but play a crucial role for recycling radio pulsars to high spin rates and low B-fields, which make them detectable for billions of years to follow. A third outcome of this study is therefore a better knowledge of the evolution of high-mass X-ray binaries which again can be confronted with observations. To model the population of compact binaries the evolution of a large sample of binary star systems is needed - from the zero age main sequence, via mass transfer and supernova explosions - in order to predict the number of both observable radio pulsars orbiting NS and BH as well as the advanced LIGO detection rate of mergers. To achieve these goals we make use of advanced population synthesis techniques with Monte Carlo simulations and explore new aspects of massive binary stellar evolution for the first time.