在ΛCDM宇宙中模拟Kilonovae
Simulating Kilonovae in the ΛCDM Universe
摘要：
Kilonovae是在中子星-中子星合并（NNM）或中子星-黑洞合并（NBM）之后产生的闪光。在这项工作中，我们使用千禧年模拟，结合半解析的星系形成模型-GABE（星系组装与二进制演化），采用二进制恒星星族合成模型，探讨宇宙事件率的千新星，和他们的宿主星系的宇宙学背景下的属性。我们发现超新星反冲速度为0 km/s的模型与观测结果最吻合，除了一些双中子星的形成通道外。这表明NNM更倾向于起源于具有低反冲速度的二元体系。当V $_{\rm kick}$ =0 km/s时，z=0时NNM和NBM的宇宙事件率分别为283 Gpc $^{-3}$ yr $^{-1}$和91 Gpc $^{-3}$ yr $^{-1}$，与LVC GWTC-1的约束勉强一致。对于银河系质量的星系，我们预测了NNM率为$25.7^{+59.6}_{-7.1}$ Myr $^{-1}$，这也与观测到的银河系中双星中子星的性质相符合.考虑到银河系质量星系历史中的所有NNM事件，我们发现在NNM和NBM事件中，A>79的平均r过程元素产额应该是0.01 M $_{\odot}$，才能与观测结果相一致。我们认为，GW 170817的宿主星系NGC 4993是NNM的典型宿主星系。然而，一般来说，NNM和NBM倾向于居住在年轻的，蓝色的，恒星形成的，晚型星系，恒星质量和气体金属丰度分布峰值分别在$10^{10.65}$ M $_{\odot}$和8.72-8.85。通过在宇宙学背景下研究千新星宿主星系，当我们在即将到来的未来有更多的事件时，有希望更好地约束模型细节。（节略）
英文摘要：
Kilonovae are optical flashes produced in the aftermath of neutron star-neutron star mergers (NNMs) or neutron star-black hole mergers (NBMs). In this work, we use the Millennium Simulation, combined with a semi-analytic galaxy formation model--GABE (Galaxy Assembly with Binary Evolution) which adopts binary stellar population synthesis models, to explore the cosmic event rate of kilonovae, and the properties of their host galaxies in a cosmological context. We find that model with supernova kick velocity of 0 km/s fits the observation best, in agreement with the exception of some formation channels of binary neutron star. This indicates that NNMs prefer to originate from binary systems with low kick velocities. With V$_{\rm kick}$=0 km/s, the cosmic event rate of NNMs and NBMs at z=0 are 283 Gpc$^{-3}$yr$^{-1}$ and 91 Gpc$^{-3}$yr$^{-1}$, respectively, marginally consistent with the constraint from LVC GWTC-1. For Milky Way-mass galaxies, we predict the NNM rate is $25.7^{+59.6}_{-7.1}$ Myr$^{-1}$, which is also in good agreement with the observed properties of binary neutron stars in the Milky Way. Taking all the NNMs into account in the history of Milky Way-mass galaxies, we find that the averaged r-process elements yield with A>79 in a NNM and NBM event should be 0.01 M$_{\odot}$ to be consistent with observation. We conclude that NGC 4993, the host galaxy of GW170817, is a typical host galaxy for NNMs. However, generally NNMs and NBMs tend to reside in young, blue, star-forming, late-type galaxies, with stellar mass and gaseous metallicity distribution peaking at $10^{10.65}$ M$_{\odot}$ and 8.72-8.85, respectively. By studying kilonovae host galaxies in the cosmological background, it is promising to constrain model details better when we have more events in the forthcoming future. (abridged)
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