论文标题
GW190412是否来自层次结构3+1四倍配置？
Was GW190412 born from a hierarchical 3+1 quadruple configuration?
论文作者
论文摘要
The gravitational wave source GW190412 is a binary black hole (BBH) merger with three unique properties: i) its mass ratio is about 0.28, the lowest found so far, ii) it has a relatively high positive effective spin parameter χ_eff=0.25, and iii) it is observed to be precessing due to in-plane projected spin of the binary with an in-plane precession parameter χ_p=0.3. BBH构造的两个主要地层通道无法解释GW190412：野外形成方案无法解释观察到的进动，除非通过调用大型出生踢，而在密集的恒星系统中的动态组装效率低，从而产生如此低的质量比率BBH合并。在这里，我们调查了“ 3+1”配置中宽分层四核系统中的“双重合并”是否可以解释GW190412的独特属性。在这种情况下，一个紧凑的对象四核系统经历了两种合并：首先，由于世俗的混沌进化而导致最内向的轨道合并中的两个紧凑型物体。稍后，由于世俗的利多夫 - 科泽（Lidov-Kozai）振荡，合并的紧凑型物体与另一个紧凑的物体合并。我们发现我们的场景与GW190412一致。特别是，我们发现围绕χ_p= 0.2的优先投影旋转。但是，双重合并的可能性很小，这些系统的形成效率尚不确定。如果GW190412起源于3+1四倍的双重合并，我们发现强烈的限制是，第一个合并可能发生在最内向轨道中的大致相等的质量BHS之间，因为否则少量BHS的后坐力速度否则会破坏该系统。
The gravitational wave source GW190412 is a binary black hole (BBH) merger with three unique properties: i) its mass ratio is about 0.28, the lowest found so far, ii) it has a relatively high positive effective spin parameter χ_eff=0.25, and iii) it is observed to be precessing due to in-plane projected spin of the binary with an in-plane precession parameter χ_p=0.3. The two main formation channels of BBH formation fail to account for GW190412: field formation scenarios cannot explain the observed precession unless by invoking large natal kicks, and dynamical assembly in dense stellar systems is inefficient in producing such low mass-ratio BBH mergers. Here, we investigate whether "double mergers" in wide hierarchical quadruple systems in the "3+1" configuration could explain the unique properties of GW190412. In this scenario, a compact object quadruple system experiences two mergers: first, two compact objects in the innermost orbit merge due to secular chaotic evolution. At a later time, the merged compact object coalesces with another compact object due to secular Lidov-Kozai oscillations. We find that our scenario is consistent with GW190412. In particular, we find a preferential projected spin around χ_p=0.2. However, the likelihood of a double merger is small and the formation efficiency of these systems is uncertain. If GW190412 originated from a double merger in a 3+1 quadruple, we find a strong constraint that the first merger likely occurred between roughly equal-mass BHs in the innermost orbit, since the recoil velocity from unequal-mass BHs would otherwise have disrupted the system.
