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arXiv 1502.05402astro-ph.HEgr-qc
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黑洞-中子星双星的动力学质量抛射

Dynamical mass ejection from black hole-neutron star binaries

Koutarou Kyutoku, Kunihito Ioka, Hirotada Okawa, Masaru Shibata, Keisuke Taniguchi

摘要:

利用相对论数值模拟方法研究了黑洞-中子星双星并合过程中动态喷射物质的性质。系统地研究了双星质量比、黑洞自旋和中子星物质状态方程对喷出物性质的影响。动力学物质抛射主要由潮汐力矩驱动,并且抛射物比双中子星合并的抛射物具有更大的各向异性。特别是,动力喷射物集中在轨道平面周围,半张角为10- 20度,通常只扫过一半平面。典型情况下,喷出物质量可达~0.1M_sun,速度为亚相对论性,约为0.2- 0.3c。对于较大的二元质量比值,即,黑洞的质量越大。残留的黑洞-盘系统由于喷出物的线动量而获得O(100)km/s的反冲速度,并且这很容易支配由于引力辐射而产生的反冲速度。还研究了合并后物质的结构、动力学喷出物的速度分布、回落率和引力波。我们还讨论了喷出物各向异性对电磁同行的影响,特别是macronova/kilonova和同步辐射无线电发射,开发分析模型。

英文摘要:

We investigate properties of material ejected dynamically in the merger of black hole-neutron star binaries by numerical-relativity simulations. We systematically study the dependence of ejecta properties on the mass ratio of the binary, spin of the black hole, and equation of state of the neutron-star matter. Dynamical mass ejection is driven primarily by tidal torque, and the ejecta is much more anisotropic than that from binary neutron star mergers. In particular, the dynamical ejecta is concentrated around the orbital plane with a half opening angle of 10--20deg and often sweeps out only a half of the plane. The ejecta mass can be as large as ~0.1M_sun, and the velocity is subrelativistic with ~0.2--0.3c for typical cases. The ratio of the ejecta mass to the bound mass (disk and fallback components) is larger, and the ejecta velocity is larger, for larger values of the binary mass ratio, i.e., for larger values of the black-hole mass. The remnant black hole-disk system receives a kick velocity of O(100)km/s due to the ejecta linear momentum, and this easily dominates the kick velocity due to gravitational radiation. Structures of postmerger material, velocity distribution of the dynamical ejecta, fallback rates, and gravitational waves are also investigated. We also discuss the effect of ejecta anisotropy on electromagnetic counterparts, specifically a macronova/kilonova and synchrotron radio emission, developing analytic models.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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