Stability and pulsation of the first dark stars
Stability and pulsation of the first dark stars
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DOI：
10.1093/mnras/stab420
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发表时间：
2020-10
影响因子：
4.8
通讯作者：
T. Rindler-Daller;K. Freese;R. Townsend;L. Visinelli
中科院分区：
文献类型：
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作者：
T. Rindler-Daller;K. Freese;R. Townsend;L. Visinelli
宇宙中形成的第一个明亮的天体可能不是“普通的”聚变驱动的恒星，而是“暗恒星”(DSS)，其动力来自于以弱相互作用大质量粒子(WIMP)的形式湮灭暗物质(DM)。如果被发现，DSS可以提供一个独特的实验室来测试DM模型。DSS与生俱来的质量为$M_ODOT$，并可能增长到几百万个太阳质量；在这项工作中，我们研究了质量高达$SIM\1000，M_\ODOT$的早期DSS的性质，其中WIMPS的质量为$100$GeV。我们将以前实现的DM能量源改进为恒星演化程序MESA。结果表明，DSS的增长不受天体物理效应的限制：DSS不存在动力学不稳定性；DSS不受超爱丁顿风驱动的质量损失的影响。我们测试了以前工作的假设，即每次WIMP湮灭的注入能量在整个恒星中是恒定的；放松这个假设不会改变DSS的性质。此外，我们还研究了DS脉动，首次使用线性脉动编码回旋研究了非绝热脉动模式。我们发现，在氢或氦被(部分)电离的层中，质量小于SIM200，MODOT的DSS中的声学模式是由$kappa-Gamma和$Gamma机制激发的。此外，我们还表明，与吸积率相比，脉动引起的潜在质量损失率可以忽略不计。
The first bright objects to form in the Universe might not have been "ordinary" fusion-powered stars, but "Dark Stars" (DSs) powered by the annihilation of dark matter (DM) in the form of Weakly Interacting Massive Particles (WIMPs). If discovered, DSs can provide a unique laboratory to test DM models. DSs are born with a mass of order $M_\odot$ and may grow to a few million solar masses; in this work we investigate the properties of early DSs with masses up to $\sim \! 1000 \, M_\odot$, fueled by WIMPS weighing $100$ GeV. We improve the previous implementation of the DM energy source into the stellar evolution code MESA. We show that the growth of DSs is not limited by astrophysical effects: DSs up to $\sim \! 1000 \, M_\odot$ exhibit no dynamical instabilities; DSs are not subject to mass-loss driven by super-Eddington winds. We test the assumption of previous work that the injected energy per WIMP annihilation is constant throughout the star; relaxing this assumption does not change the properties of the DSs. Furthermore, we study DS pulsations, for the first time investigating non-adiabatic pulsation modes, using the linear pulsation code GYRE. We find that acoustic modes in DSs of masses smaller than $\sim \! 200 \, M_\odot$ are excited by the $\kappa-\gamma$ and $\gamma$ mechanism in layers where hydrogen or helium is (partially) ionized. Moreover, we show that the mass-loss rates potentially induced by pulsations are negligible compared to the accretion rates.