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arXiv 1710.03033astro-ph.GA
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用星系并合树探索宇宙适居性演化

Exploring the Cosmic Evolution of Habitability with Galaxy Merger Trees

E. R. Stanway, M. J. Hoskin, M. A. Lane, G. C. Brown, H. J. T. Childs, S. M. L. Greis, A. J. Levan

摘要:

我们结合推断的星系属性,从半解析星系演化模型,将暗物质晕合并树与新的估计超新星和伽马射线暴率作为金属丰度的函数,从恒星星族合成模型,将二元相互作用。我们用这些来探索恒星质量分数的星系照射充满活力的天体物理瞬变和它在宇宙时间的演变,从而这是潜在的生活像我们自己的分数。我们发现,宇宙中18%的恒星质量可能在过去的2.6亿年内受到辐射,其中GRB占主导地位。我们没有看到辐射恒星质量分数对恒星质量或星系环境的丰富程度的强烈依赖。我们认为一个有代表性的合并树作为一个本地集团的类似物,并发现有星系在所有质量的保留了高宜居分数(> 40%)在过去的6 Gyr,但也有星系在所有质量的合并历史和相关的恒星形成,使星系有效地不适合居住。这说明了在评估可居住性的宇宙演化时需要考虑详细的合并树。

英文摘要:

We combine inferred galaxy properties from a semi-analytic galaxy evolution model incorporating dark matter halo merger trees with new estimates of supernova and gamma ray burst rates as a function of metallicity from stellar population synthesis models incorporating binary interactions. We use these to explore the stellar mass fraction of galaxies irradiated by energetic astrophysical transients and its evolution over cosmic time, and thus the fraction which is potentially habitable by life like our own. We find that 18 per cent of the stellar mass in the Universe is likely to have been irradiated within the last 260 Myr, with GRBs dominating that fraction. We do not see a strong dependence of irradiated stellar mass fraction on stellar mass or richness of the galaxy environment. We consider a representative merger tree as a Local Group analogue, and find that there are galaxies at all masses which have retained a high habitable fraction (>40 per cent) over the last 6 Gyr, but also that there are galaxies at all masses where the merger history and associated star formation have rendered galaxies effectively uninhabitable. This illustrates the need to consider detailed merger trees when evaluating the cosmic evolution of habitability.

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