Gravitational-wave Signatures from Compact Object Binaries in the Galactic Center
Gravitational-wave Signatures from Compact Object Binaries in the Galactic Center
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DOI：
10.3847/1538-4357/ac088d
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发表时间：
2020-10
期刊：
影响因子：
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通讯作者：
Huiyi Wang;A. Stephan;S. Naoz;Bao-Minh Hoang;K. Breivik
中科院分区：
文献类型：
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作者：
Huiyi Wang;A. Stephan;S. Naoz;Bao-Minh Hoang;K. Breivik
几乎每个星系的中心都有一个超大质量黑洞（SMBH），包括银河系。最近的研究表明，这些独特的地方预计将拥有大量的恒星和紧凑的物体双星。这些二进制文件形成分层三重系统的SMBH和偏心Kozai-Lidov（EKL）机制。在这里，我们估计潜在的引力波发射从这些紧凑的物体的激光干涉仪空间天线（丽莎）和激光干涉仪引力波天文台（LIGO）和处女座探测器的频带内的可探测性。我们产生一个后EKL人口的明星在洛希极限交叉的发病，并按照他们的演变紧凑的对象二进制文件。作为概念的证明，我们采用两种金属丰度，太阳金属丰度（Z = 0.02）和15%（Z = 0.003）。我们证明了在丽莎的观测时间尺度上，黑洞（BH）双星（BH-BH）和白色矮星（WD）双星通过EKL辅助合并通道提供了最突出的GW源。涉及中子星（NS）的系统不太可观察，但可能通过不同的合并渠道丰富。我们对Z = 0.02（Z = 0.003）的BH-BH的群体合成转化为在1 Gpc 3球体内使用LIGO每年发生104（24）次事件。我们还估计，在我们银河系中心（可能还有其他星系）的内秒差距内，在丽莎波段可见的双星数量约为14-150 WD-WD，0-2 NS-BH，0.2-4 NS-NS和0.3-20 BH-BH。
Almost every galaxy has a supermassive black hole (SMBH) residing at its center, the Milky Way included. Recent studies suggest that these unique places are expected to host a high abundance of stellar and compact object binaries. These binaries form hierarchical triple systems with the SMBH and undergo the eccentric Kozai–Lidov (EKL) mechanism. Here we estimate the detectability of potential gravitational-wave emission from these compact objects within the frequency band of the Laser Interferometer Space Antenna (LISA) and Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo detectors. We generate a post-EKL population of stars at the onset of Roche limit crossing and follow their evolution to compact object binaries. As a proof of concept, we adopt two metallicities, solar metallicity (Z = 0.02) and 15% of it (Z = 0.003). We demonstrate that over the observation timescale of LISA, black hole (BH) binaries (BH–BH) and white dwarf (WD) binaries provide the most prominent GW sources via the EKL-assisted merger channel. Systems involving neutron stars (NSs) are less observable but possibly abundant through different merger channels. Our population synthesis of BH–BH with Z = 0.02 (Z = 0.003) translates to ∼4 (24) events per year with LIGO within a 1 Gpc3 sphere. We also estimated the number of binaries visible in the LISA band within the inner parsec of our Galactic center (and possibly other galaxies) to be about 14–150 WD–WD, 0–2 NS–BH, 0.2–4 NS–NS, and 0.3–20 BH–BH.