arXiv 2006.008492020-06astro-ph.SRastro-ph.GAastro-ph.HE

双星中的核心坍缩超新星是银河系超逃逸星的起源

Core-Collapse Supernovae in Binaries as the Origin of Galactic Hyper-Runaway Stars

Fraser A. Evans, Mathieu Renzo, Elena Maria Rossi

备注：: Accepted for publication in MNRAS following minor revisions. 22 pages, 6 figures, 4 tables
DOI：: 10.1093/mnras/staa2334

摘要：

有几颗恒星被探测到以接近或超过银河系逃逸速度的速度移动，可能起源于银河系圆盘。我们定量探讨的“二进制超新星的情况下”的假设，其中这些“超失控”的恒星被抛出时，他们的密切，大规模的二进制同伴进行核心坍缩超新星和二进制被打乱了大的奇特的速度。我们进行了广泛的二进制人口合成模拟不断发展的大规模系统，以确定的假设和参数，最影响快速恒星的弹射率。在一个模拟量身定制的喷射快星，我们发现最有可能的超逃逸恒星的祖先二是由一个大质量的（$\sim$ $30\,\mathrm{M_{\odot}}$）的主要和一个$\sim$伴星的轨道周期收缩到$\lesssim$ 1天之前的核心崩溃后，一个共同的信封阶段。由主星形成的黑洞残骸必须接受出生踢$\gtrsim$ 1000 $\mathrm{km\ s^{-1}}$，以破坏双星并以很大的速度喷射伴星。我们比较在这些模拟中产生的快速恒星的早期型银河系超逃逸恒星候选人的当代人口普查。我们发现，这些罕见的对象可能会产生足够的数量，只有当约束不佳的二进制演化参数的强度，核心崩溃后，残余的出生踢和共同的包络效率调整到目前不支持的值-但不排除-由文献。我们讨论了观测的影响，可能会限制这些假定的祖系统的存在。

英文摘要：

Several stars detected moving at velocities near to or exceeding the Galactic escape speed likely originated in the Milky Way disc. We quantitatively explore the `binary supernova scenario' hypothesis, wherein these `hyper-runaway' stars are ejected at large peculiar velocities when their close, massive binary companions undergo a core-collapse supernova and the binary is disrupted. We perform an extensive suite of binary population synthesis simulations evolving massive systems to determine the assumptions and parameters which most impact the ejection rate of fast stars. In a simulation tailored to eject fast stars, we find the most likely hyper-runaway star progenitor binary is composed of a massive ($\sim$$30\,\mathrm{M_{\odot}}$) primary and a $\sim$$3-4\,\mathrm{M_{\odot}}$ companion on an orbital period that shrinks to $\lesssim$1 day prior to the core collapse following a common envelope phase. The black hole remnant formed from the primary must receive a natal kick $\gtrsim$1000 $\mathrm{km\ s^{-1}}$ to disrupt the binary and eject the companion at a large velocity. We compare the fast stars produced in these simulations to a contemporary census of early-type Milky Way hyper-runaway star candidates. We find that these rare objects may be produced in sufficient number only when poorly-constrained binary evolution parameters related to the strength of post-core collapse remnant natal kicks and common envelope efficiency are adjusted to values currently unsupported -- but not excluded -- by the literature. We discuss observational implications that may constrain the existence of these putative progenitor systems.

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