论文标题
差分积聚对重力波背景和当今MBH二元种群的影响
The effect of differential accretion on the Gravitational Wave Background and the present day MBH Binary population
论文作者
论文摘要
由于银河合并而形成的大型黑洞二进制文件（MBHB）。但是，目前尚不清楚它们是否通常在哈勃时期内合并，以及积聚如何影响其进化。这些问题将由PULSAR计时阵列（PTA）解决，该问题旨在检测MBHB在Inspiral的最后一个Myrs期间发出的GW背景（GWB）。在这里，我们研究了差异积聚对MBHB合并率，chirp质量和所得GWB光谱的影响。我们使用半分析模型从Illustris流体动力学模拟中进化了MBHB样本，并首次使用二元增生模型自我一致地发展了它们的质量。在所有型号中，MBHBS与中位数总质量的合并最高$ 1.5 \ times 10^8 m _ {\ odot} $，最高$ 3-4 $ $ 3-4 $倍，比忽略积聚的型号大。 In our model with the largest plausible impact, the median mass ratio of coalescing MBHBs increases by a factor $3.6$, the coalescence rate by $52.3\%$, and the GWB amplitude by a factor $4.0$, yielding a dimensionless GWB strain $A_{yr^{-1}} = 1 \times 10^{-15}$.我们利用积聚对主要MBH的模型将合并MBHB的中值质量比降低了$ 2.9 $，并且产生了GWB振幅$ a_ {yr^{ - 1}} = 3.1 = 3.1 \ times 10^{ - 16} $。尽管合并时MBHB质量更高，但这几乎与我们的模型忽略了积聚几乎没有区别。 \ textbf {我们进一步预测了低红移宇宙中失速MBHB的二进制分离和质量比分布，并发现这些分离依赖于二进制积聚模型。这提出了对MBHB种群的合并率和增值模型的组合观察限制的潜力。}
Massive black hole binaries (MBHBs) form as a consequence of galaxy mergers. However, it is still unclear whether they typically merge within a Hubble time, and how accretion may affect their evolution. These questions will be addressed by pulsar timing arrays (PTAs), which aim to detect the GW background (GWB) emitted by MBHBs during the last Myrs of inspiral. Here we investigate the influence of differential accretion on MBHB merger rates, chirp masses and the resulting GWB spectrum. We evolve a MBHB sample from the Illustris hydrodynamic cosmological simulation using semi-analytic models and for the first time self-consistently evolve their masses with binary accretion models. In all models, MBHBs coalesce with median total masses up to $1.5 \times 10^8 M_{\odot}$, up to $3-4$ times larger than in models neglecting accretion. In our model with the largest plausible impact, the median mass ratio of coalescing MBHBs increases by a factor $3.6$, the coalescence rate by $52.3\%$, and the GWB amplitude by a factor $4.0$, yielding a dimensionless GWB strain $A_{yr^{-1}} = 1 \times 10^{-15}$. Our model that favours accretion onto the primary MBH reduces the median mass ratio of coalescing MBHBs by a factor of $2.9$, and yields a GWB amplitude $A_{yr^{-1}} = 3.1 \times 10^{-16}$. This is nearly indistinguishable from our model neglecting accretion, despite higher MBHB masses at coalescence. \textbf{We further predict binary separation and mass ratio distributions of stalled MBHBs in the low-redshift universe, and find that these depend sensitively on binary accretion models. This presents the potential for combined EM and GW observational constraints on merger rates and accretion models of MBHB populations.}
