超致密X射线双星引力波辐射

The gravitational wave radiation from ultracompact X-ray binaries

超简并X射线源由中子星和充满洛希瓣的白矮星双星组成,该类双星系统轨道周期极短(约小于80 min).对此类双星系统的数值计算表明其在演化过程中可以产生强引力波辐射.以目前观测到的最短轨道周期超简并X射线源4U 1820-30为例,我们模拟了该双星系统的轨道和质量演化,发现物质交流稳定性判据建议该系统曾经经历过非稳定的物质交流,该系统的引力波辐射频率变化在10^(-5) a^(-1)的量级.通过比较不同质量双星的轨道周期和引力波频率随时间的演化,我们提出可以通过测量引力波频率变化的方法来研究此类双星星族的演化过程,也可以通过该方法来搜寻较大质量短轨道周期黑洞白矮星等双星系统.

The ultracompact X-ray sources are believed to be binaries consisting of neutron stars and Roche lobe filling white dwarfs. Using this binary model, we numerically calculated the gravitational waves(GW) radiated from ultracompact X-ray sources. Our results indicate that S/N of the shortest orbital period X-ray source 4U 1820-30 can reach -3 by GW detectors with LISA-like sensitivity curves, and its GW frequency change is about 10^-5 a^-1. The mass transfer stability criteria suggests that this binary system has experienced unstable mass transfer. Measuring the first-order time derivative of GW frequency(i.e. orbital period) of these binaries may allow us to study the evolution the binary population, and search for binaries with high masses and short orbital periods, e.g. black hole white dwarf binaries.