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arXiv 2301.01941astro-ph.HE
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金属富集超大质量恒星的演化与爆发:富质子广义相对论不稳定性超新星

Evolution and explosions of metal enriched supermassive stars: proton rich general relativistic instability supernovae

Chris Nagele, Hideyuki Umeda, Koh Takahashi

AI总结:

本研究通过广义相对论流体动力学模拟和核网络后处理,探究了富金属超大质量恒星因广义相对论径向不稳定性在氢燃烧阶段坍缩并可能爆发为富质子超新星的过程,发现其爆发特征为氮和中等质量元素增强及轻元素受抑。

摘要:

超大质量黑洞的形成提出了挑战,主要原因是观测到了高红移类星体,此外还因为目前缺乏对中等质量黑洞的观测。产生超大质量黑洞的一种可能情景是由两个富气星系并合触发的直接坍缩。该情景允许形成具有太阳金属量的超大质量恒星,其中金属量的增强是由极快吸积实现的。我们研究了在氢燃烧期间因广义相对论径向不稳定性而坍缩的金属富集超大质量恒星的行为。这些恒星同时包含氢和金属,因此可能因CNO循环(碳-氮-氧)和rp过程(快质子俘获)而爆发。我们针对一系列质量和金属量执行了一组恒星演化模拟,包括有质量损失和忽略质量损失的情况。我们通过在广义相对论中求解脉动方程来评估这些超大质量恒星的稳定性。当恒星变得不稳定时,我们执行了1D广义相对论流体动力学模拟,该模拟耦合了包含中微子反应冷却的153同位素核网络,以确定恒星是否爆发。如果恒星确实爆发,我们使用包含额外富质子同位素的514同位素网络对核合成进行后处理。这些爆发的特征是氮和中等质量元素($16\geq\rm{A}\geq25$)的增强,以及轻元素($8\geq\rm{A}\geq14$)的受抑,并且我们对最近在GN-z11中观测到的超太阳氮丰度进行了评论。

英文摘要:

The assembly of supermassive black holes poses a challenge primarily because of observed quasars at high redshift, but additionally because of the current lack of observations of intermediate mass black holes. One plausible scenario for creating supermassive black holes is direct collapse triggered by the merger of two gas rich galaxies. This scenario allows the creation of supermassive stars with solar metallicity, where the enhanced metallicity is enabled by extremely rapid accretion. We investigate the behavior of metal enriched supermassive stars which collapse due to the general relativistic radial instability during hydrogen burning. These stars contain both hydrogen and metals and thus may explode due to the CNO cycle (carbon-nitrogen-oxygen) and the rp process (rapid proton capture). We perform a suite of stellar evolution simulations for a range of masses and metallicities, both including and neglecting mass loss. We evaluate the stability of these supermassive stars by solving the pulsation equation in general relativity. When the stars becomes unstable, we perform 1D general relativistic hydrodynamical simulations coupled to a 153 isotope nuclear network with cooling from neutrino reactions, in order to determine if the stars explode. If the stars do explode, we post process the nucleosynthesis using a 514 isotope network which includes additional proton rich isotopes. These explosions are characterized by enhanced nitrogen and intermediate mass elements ($16\geq\rm{A}\geq25$), and suppressed light elements ($8\geq\rm{A}\geq14$), and we comment on recent observations of super-solar nitrogen in GN-z11.

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