arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2006.06647astro-ph.GAgr-qc
收藏

宇宙学框架下大质量黑洞双星的内旋和自旋演化

Massive black hole binary inspiral and spin evolution in a cosmological framework

Mohammad Sayeb, Laura Blecha, Luke Zoltan Kelley, Davide Gerosa, Michael Kesden, July Thomas

摘要:

大质量黑洞(MBH)双星螺旋内的时间尺度是不确定的,它们的自旋甚至更不受约束。自旋错位,以及不相等的质量比和自旋幅度,在引力辐射中引入了不对称性,这给合并的MBH带来了反冲。了解MBH双星自旋如何演化对于确定它们的反冲速度、LISA可探测到的引力波(GW)波形以及它们在星系中的合并后留存率以及随后的合并率至关重要。在这里,我们提出了一个新的研究,介绍了一个亚分辨率模型的气体和GW驱动的MBH二进制自旋演化使用人口的吸积MBH从插图宇宙流体动力学模拟。我们还通过动力学摩擦,恒星散射,粘性气体阻力和GW排放模型的次分辨率二进制inspiral。我们的模型假设微分吸积,这会导致更大的调整二级MBH自旋不等质量合并。我们发现在我们的人群中有47%的MBH通过$z=0$合并。其中,在我们的(保守的)基准模型中,19%的公司在合并时有未对齐的初选,10%的公司在合并时有未对齐的次级初选。然而,MBH失调分数强烈依赖于吸积盘参数。减少吸积率的一个因素的100,在一个较厚的光盘,产生79%和42%的初级和次级的错位,分别。即使在基准模型中,超过12%的双星经历了$>500$ km s $^{-1}$的反冲,这可能会使它们至少暂时离开星系核。我们还发现,大量的系统经历强进动。

英文摘要:

Massive black hole (MBH) binary inspiral time scales are uncertain, and their spins are even more poorly constrained. Spin misalignment, along with unequal mass ratios and spin magnitudes, introduces asymmetry in the gravitational radiation, which imparts a recoil kick to the merged MBH. Understanding how MBH binary spins evolve is crucial for determining their recoil velocities, their gravitational wave (GW) waveforms detectable with LISA, as well as their post-merger retention rate in galaxies and thus their subsequent merger rate. Here we present a novel study that introduces a sub-resolution model for gas- and GW-driven MBH binary spin evolution using a population of accreting MBHs from the Illustris cosmological hydrodynamics simulations. We also model sub-resolution binary inspiral via dynamical friction, stellar scattering, viscous gas drag, and GW emission. Our model assumes differential accretion, which causes greater alignment of the secondary MBH spin in unequal-mass mergers. We find that 47% of the MBHs in our population merge by $z=0$. Of these, 19% have misaligned primaries and 10% have misaligned secondaries at the time of merger in our (conservative) fiducial model. The MBH misalignment fraction depends strongly on the accretion disc parameters, however. Reducing accretion rates by a factor of 100, in a thicker disc, yields 79% and 42% misalignment for primaries and secondaries, respectively. Even in the fiducial model, more than 12% of binaries experience recoils of $>500$ km s$^{-1}$, which could displace them at least temporarily from galactic nuclei. We additionally find that a significant number of systems experience strong precession.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑