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arXiv 1101.3591gr-qcastro-ph.CO
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自旋部分对准的大质量黑洞双星参数测量

Measuring parameters of massive black hole binaries with partially aligned spins

Ryan N. Lang, Scott A. Hughes, Neil J. Cornish

摘要:

未来的空间引力波探测器LISA将能够测量合并的大质量黑洞双星的参数,通常具有极高的精度。先前的工作已经证明,黑洞自旋可以对参数测量的准确性产生强烈的影响。相对论性自旋诱导的进动调制波形的方式,可以打破参数之间的简并,在原则上显着提高如何以及他们的测量。然而,最近的研究表明,对于天体物理学上的一个重要的二元黑洞子集,自旋进动可能很弱:那些自旋由于与气体的相互作用而对齐的黑洞。在本文中,我们研究如何以及二进制的参数可以测量时,它的自旋部分对齐,并比较结果使用波形,包括更高的后牛顿谐波的那些被截断在领先的四极杆顺序。我们发现,削弱的进动可以大大降低参数估计。这种退化对于外部参数天空位置和距离特别具有破坏性。在没有高次谐波的情况下,LISA通常定位一个几乎对齐的双星的天空位置,其精确度比自旋方向随机的双星低$\sim 6$。因此,对于最有可能产生电磁对应物的富含气体的系统,我们对源的天空位置的了解将是最糟糕的。幸运的是,波形的高次谐波可以弥补这种退化。通过在我们的波形模型中包括超越四极的谐波,我们发现,大部分的二进制的参数测量的精度可以大大提高。在某些情况下,参数也可以在部分对齐的二进制中测量,因为当二进制自旋是随机的时,它们可以被测量。

英文摘要:

The future space-based gravitational wave detector LISA will be able to measure parameters of coalescing massive black hole binaries, often to extremely high accuracy. Previous work has demonstrated that the black hole spins can have a strong impact on the accuracy of parameter measurement. Relativistic spin-induced precession modulates the waveform in a manner which can break degeneracies between parameters, in principle significantly improving how well they are measured. Recent studies have indicated, however, that spin precession may be weak for an important subset of astrophysical binary black holes: those in which the spins are aligned due to interactions with gas. In this paper, we examine how well a binary's parameters can be measured when its spins are partially aligned and compare results using waveforms that include higher post-Newtonian harmonics to those that are truncated at leading quadrupole order. We find that the weakened precession can substantially degrade parameter estimation. This degradation is particularly devastating for the extrinsic parameters sky position and distance. Absent higher harmonics, LISA typically localizes the sky position of a nearly aligned binary a factor of $\sim 6$ less accurately than for one in which the spin orientations are random. Our knowledge of a source's sky position will thus be worst for the gas-rich systems which are most likely to produce electromagnetic counterparts. Fortunately, higher harmonics of the waveform can make up for this degradation. By including harmonics beyond the quadrupole in our waveform model, we find that the accuracy with which most of the binary's parameters are measured can be substantially improved. In some cases, parameters can be measured as well in partially aligned binaries as they can be when the binary spins are random.

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