Revisiting non-linearity in binary black hole mergers

Revisiting the ringdown of GW150914

We examine recent claims that evidence for an overtone in the ringdown of the GW150914 binary black hole merger was a result of noise anomalies. We cannot reproduce these claims, finding that our previous analysis of this event is robust to data analysis choices and consistent with the expectation that strain after the peak is well described as a superposition of quasinormal modes of the remnant black hole. We discuss the meaning and implications of establishing that any specific ringdown mode was detected, and argue that it is misguided to expect actual LIGO-Virgo data to inform the discussio…

重新审视Hayward黑洞的热力学并探索双黑洞并合界限

Revisiting Thermodynamics of the Hayward Black Holes and Exploring Binary Merger Bounds

本文重新审视Hayward黑洞的热力学，推导出双等质量黑洞碰撞后最终质量的界限，并讨论Hayward参数对热力学和并合性质的影响。

使用非平面偏心波形模型重新审视 GW150914

Revisiting GW150914 with a non-planar, eccentric waveform model

本文用兼具偏心率与自旋进动的 EOB 非平面波形模型重新分析 GW150914，对比多种双星情形，确认其符合准圆、慢自转双黑洞并合并更新源参数。

Revisiting the lower bound on tidal deformability derived by AT 2017gfo

We revisit the lower bound on binary tidal deformability tilde{Lambda} imposed by a luminous kilonova/macronova, AT 2017gfo, by numerical-relativity simulations of models that are consistent with gravitational waves from the binary neutron star merger GW170817. Contrary to the claim made in the literature, we find that binaries with tilde{Lambda}<~400 can explain the luminosity of AT 2017gfo, as long as moderate mass ejection from the remnant is assumed as had been done in previous work. The reason is that the maximum mass of a neutron star is not strongly correlated with the tidal deformabili…

Revisiting Event Horizon Finders

Event horizons are the defining physical features of black hole spacetimes, and are of considerable interest in studying black hole dynamics. Here, we reconsider three techniques to localise event horizons in numerical spacetimes: integrating geodesics, integrating a surface, and integrating a level-set of surfaces over a volume. We implement the first two techniques and find that straightforward integration of geodesics backward in time to be most robust. We find that the exponential rate of approach of a null surface towards the event horizon of a spinning black hole equals the surface gravi…

重新审视黑洞踢动与多极不对称性之间的关系

Revisiting the relationship of black-hole kicks and multipole asymmetries

本文全面分析了黑洞双星并合中线性动量通量与多极不对称性的关系，发现大的不对称性并非总是导致大踢动，并提供了测试波形模型的工具，修复了IMRPhenomXO4a的相位定义问题。