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arXiv 2109.00754gr-qc
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中等质量比双星系统中的引力波记忆效应综述

Survey of gravitational wave memory in intermediate mass ratio binaries

Tousif Islam, Scott E. Field, Gaurav Khanna, Niels Warburton

AI总结:

本文针对中等质量比旋近系统的引力波记忆效应开展综合分析,结合黑洞微扰理论计算位移与自旋记忆,探究其对质量比、自旋等参数的依赖及探测前景,发现层级并合形成的大质量系统或为记忆探测的重要候选源。

摘要:

非线性引力波(GW)记忆效应是广义相对论中一个独特的预测。尽管该效应在质量相当的双星系统中已得到充分研究,但在中等质量比旋近(IMRI)系统中大多被忽视。本文针对由恒星级黑洞和中等质量黑洞构成的大质量IMRI系统,开展了记忆效应的现象学与可探测性综合分析,其中包含了次主导谐波模式的贡献。当这类系统通过层级并合形成时——例如类似GW190521的遗迹捕获一颗恒星级黑洞——IMRI系统具有总质量大、主黑洞自旋高,且可能存在残余偏心率的特点,这些特征有望提升记忆效应的探测前景。我们在部分经数值相对论波形校准的黑洞微扰理论框架下,基于m≠0的引力波形,计算了位移型和自旋型两种非线性引力波记忆。本文探究了记忆效应对质量比、自旋和偏心率的依赖关系,并分析了当前及未来引力波探测器对IMRI系统记忆信号的可探测性。研究发现:(i)尽管偏心率会在位移记忆和自旋记忆中引入额外特征,但并不会显著改变探测前景;(ii)在记忆计算中纳入更高阶模式,部分情况下可使信噪比(SNR)提升约7%;(iii)当自旋趋近于大的正值时,位移记忆的SNR会显著升高;(iv)然而,即使对于高自旋系统,大质量IMRI的自旋记忆也难以被下一代探测器探测到。研究结果表明,层级双黑洞并合可能是探测记忆效应的有前景的源,且可能对记忆效应的探测预测产生积极影响。

英文摘要:

The non-linear gravitational wave (GW) memory effect is a distinct prediction in general relativity. While the effect has been well studied for comparable mass binaries, it has mostly been overlooked for intermediate mass ratio inspirals (IMRIs). We offer a comprehensive analysis of the phenomenology and detectability of memory effects, including contributions from subdominant harmonic modes, in heavy IMRIs consisting of a stellar mass black hole and an intermediate mass black hole. When formed through hierarchical mergers, for example when a GW190521-like remnant captures a stellar mass black hole, IMRI systems have a large total mass, large spin on the primary, and possibly residual eccentricity; features that potentially raise the prospect for memory detection. We compute both the displacement and spin non-linear GW memory from the $m \neq 0$ gravitational waveforms computed within a black hole perturbation theory framework that is partially calibrated to numerical relativity waveforms. We probe the dependence of memory effects on mass ratio, spin, and eccentricity and consider the detectability of a memory signal from IMRIs using current and future GW detectors. We find that (i) while eccentricity introduces additional features in both displacement and spin memory, it does not appreciatively change the prospects of detectability, (ii) including higher modes into the memory computation can increase singal-to-noise (SNR) values by about 7\% in some cases, (iii) the SNR from displacement memory dramatically increases as the spin approaches large, positive values, (iv) spin memory from heavy IMRIs would, however, be difficult to detect with future generation detectors even from highly spinning systems. Our results suggest that hierarchical binary black hole mergers may be a promising source for detecting memory and could favorably impact memory forecasts.

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