标题： 来自MassiveBlackII模拟的随机引力波背景估计 显示英文标题

标题： An estimate of the stochastic gravitational wave background from the MassiveBlackII simulation

摘要： 一个超大质量黑洞双星种群预计会在脉冲星计时阵列（PTA）频率范围$10^{-9}$--$10^{-7}$Hz 内产生一个随机的引力波背景（SGWB）。检测这一信号是当前的观测目标，因此对其特性的预测具有重要意义。在本工作中，我们使用MassiveBlackII模拟中的超大质量黑洞双星合并来估计随机背景的特征应变。我们考察了两种模型：一种是仅由引力波驱动的双星演化模型，另一种还包含了恒星散射和环双星气体盘的影响。结果与PTA的上限一致，并且与文献中的估计类似。在参考频率$1 yr^{-1}$处，引力波驱动模型和恒星散射/气体盘模型的特征应变分别为$A_{yr^{-1}} = 6.9 \times 10^{-16}$和$A_{yr^{-1}} = 6.4 \times 10^{-16}$。使用后一种方法，我们的模型显示，在PTA频率范围内频率降低时，SGWB相比纯粹的引力波驱动模型有轻微抑制。 显示英文摘要

摘要： A population of super-massive black hole binaries is expected to generate a stochastic gravitational wave background (SGWB) in the pulsar timing array (PTA) frequency range of $10^{-9}$--$10^{-7}$ Hz. Detection of this signal is a current observational goal and so predictions of its characteristics are of significant interest. In this work we use super-massive black hole binary mergers from the MassiveBlackII simulation to estimate the characteristic strain of the stochastic background. We examine both a gravitational wave driven model of binary evolution and a model which also includes the effects of stellar scattering and a circumbinary gas disk. Results are consistent with PTA upper limits and similar to estimates in the literature. The characteristic strain at a reference frequency of $1 yr^{-1}$ is found to be $A_{yr^{-1}} = 6.9 \times 10^{-16}$ and $A_{yr^{-1}} = 6.4 \times 10^{-16}$ in the gravitational-wave driven and stellar scattering/gas disk cases, respectively. Using the latter approach, our models show that the SGWB is mildly suppressed compared to the purely gravitational wave driven model as frequency decreases inside the PTA frequency band.