Signs of higher multipoles and orbital precession in GW151226
Signs of higher multipoles and orbital precession in GW151226
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DOI：
10.1103/physrevd.106.024009
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发表时间：
2021-05
影响因子：
5
通讯作者：
H. Chia;S. Olsen;Javier Roulet;L. Dai;T. Venumadhav;B. Zackay;M. Zaldarriaga
中科院分区：
文献类型：
--
作者：
H. Chia;S. Olsen;Javier Roulet;L. Dai;T. Venumadhav;B. Zackay;M. Zaldarriaga
本文对LIGO-Virgo合作组发现的第二个双星黑洞合并GW 151226进行了重新分析。先前的分析表明，该事件的最佳拟合波形对应于$\sim 14 \，M_\odot$黑洞与$\sim 7.5 \，M_\odot$伴星的合并，质量比（$q \leq 1$）的后验分布相当平坦。在这项工作中，我们使用的波形模型，包括轨道进动和高阶辐射多极模式的影响，进行参数估计，我们发现，GW 151226的源参数向低$q$和高有效自旋（$\chi_{\rmeff}$）区域和$q$是更好地测量。新的解决方案有一个对数似然大约两个点时，无论是更高的多极或轨道岁差被忽略，可以改变天体物理学的解释GW 151226。此外，我们发现使用flat-in-$\chi{\rm eff}$ prior很有用，它不会惩罚大的$|{\fn黑体\fs22\bord1\shad0\3aHBE\4aH00\fscx67\fscy66\2cHFFFFFF\3cH8080}|$区域，以揭示GW 151226的较高似然区域。我们的解有几个有趣的性质：（a）次级黑洞质量接近天体物理学黑洞种群假设的下质量隙的上限;（B）轨道进动是由初级黑洞自旋驱动的，其无量纲大小为$\sim 0.85$，并以$\sim 57 ^\circ $的角度偏离轨道角动量。由于GW 151226是一个相对较弱的信号，因此无法明确声称在信号中检测到这些效应。
We present a reanalysis of GW151226, the second binary black hole merger discovered by the LIGO--Virgo Collaboration. Previous analysis showed that the best-fit waveform for this event corresponded to the merger of a $\sim 14 \, M_\odot$ black hole with a $\sim 7.5 \, M_\odot$ companion, and the posterior distribution in mass ratio ($q \leq 1$) is rather flat. In this work, we perform parameter estimation using a waveform model that includes the effects of orbital precession and higher-order radiative multipole modes, and we find that the source parameters of GW151226 shift towards the low $q$ and high effective spin ($\chi_{\rm eff}$) region and that $q$ is better measured. The new solution has a log likelihood roughly two points higher than when either higher multipoles or orbital precession is neglected and can alter the astrophysical interpretation of GW151226. Additionally, we find it useful to use a flat-in-$\chi{\rm eff}$ prior, which does not penalize the large $|\chi_{\rm eff}|$ region, in order to uncover the higher likelihood region for GW151226. Our solution has several interesting properties: (a) the secondary black hole mass is close to the upper limit of the hypothesized lower mass gap of astrophysical black hole population; and (b) orbital precession is driven by the primary black hole spin, which has a dimensionless magnitude as large as $\sim 0.85$ and is tilted away from the orbital angular momentum at an angle of $\sim 57^\circ$. Since GW151226 is a relatively weak signal, an unambiguous claim of the detection of these effects in the signal cannot be made.