论文标题

银河系26Al痕迹金属通过热烟囱损失

Galactic 26Al traces metal loss through hot chimneys

论文作者

Krause, Martin G. H., Rodgers-Lee, Donna, Dale, James E., Diehl, Roland, Kobayashi, Chiaki

论文摘要

放射性26AL是银河系中金属弹射的绝佳示踪剂,可以直接限制银河系进化中超新星反馈的建模。对26AL衰减线的伽马射线观测结果发现了高速度,因此需要大量的热量分量中的银河系26AL。同时,陨石数据与仿真结果结合在一起,表明大量26AL在衰减前进入恒星。我们通过模拟了一个类似乳白色的星系,并在Superbubbles中使用了大量明星的反馈,并以26AL追踪的弹射器进行了模拟。大约30-40%的喷射保持热,典型的冷却时间是GYR。 26AL追踪烟囱喂养的流出的脚步,该流出的流出量至少为50 kpc,将金属湍流地混合到模型星系的光环中。其余的温度不到约10,000 K,其温度扩散到冷气中,因此可能会迅速用于恒星形成。我们通过与具有不同全局流动模式的模拟进行比较讨论结果的鲁棒性。将分支比与冷热成分的分支比与星系,簇和簇内培养基的化学演化建模的长期平均结果相媲美。

Radioactive 26Al is an excellent tracer for metal ejection in the Milky Way, and can provide a direct constraint on the modelling of supernova feedback in galaxy evolution. Gamma-ray observations of the 26Al decay line have found high velocities and hence require a significant fraction of the Galactic 26Al in the hot component. At the same time, meteoritic data combined with simulation results suggest that a significant amount of 26Al makes its way into stars before decay. We investigated the distribution into hot and cold channels with a simulation of a Milky-Way-like galaxy with massive-star feedback in superbubbles and with ejecta traced by 26Al. About 30-40 per cent of the ejecta remain hot, with typical cooling times of the order Gyr. 26Al traces the footpoints of a chimney-fed outflow that mixes metals turbulently into the halo of the model galaxy on a scale of at least 50 kpc. The rest diffuses into cold gas with temperatures less than about 10,000 K, and may therefore be quickly available for star formation. We discuss the robustness of the result by comparison to a simulation with a different global flow pattern. The branching ratio into hot and cold components is comparable to that of longer term average results from chemical evolution modelling of galaxies, clusters and the intracluster medium.

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