论文标题
随机化学演化模型中的中子星星合并：时间延迟分布的影响
Neutron stars mergers in a stochastic chemical evolution model: impact of time delay distributions
论文作者
论文摘要
我们通过随机化学进化模型来研究银河系中[EU/FE]比率的演变，该模型考虑合并中子星作为Europium的污染物。我们通过添加中子恒星聚结的时间延迟分布而不是恒定延迟来改善先前的随机化学演化模型。随机化学进化模型可以重现[EU/Fe]数据中与中子星的合并作为独特生产者的趋势，如果假设：i）延迟时间分布$ \ propto t^{ - 1.5} $，ii）a $ m_ {eu}范围$ 9-50m _ {\ odot} $和iv）在初始质量函数（0.02）中恒定恒星的恒定分数（0.02）产生中子星星合并。我们的最佳模型是通过放松点IV获得的，并假设与金属性不同的部分。我们确认，将中子星和超新星合并为Europium生产者可以很好地达成一致性的数据，该数据与数据放宽在中子恒星的分布时间延迟上的约束相结合。采用我们的最佳模型，我们还以给定的金属性重现了[EU/FE]的分散，这取决于产生中子恒星合并的大型恒星的比例。未来的高分辨率光谱调查（例如4个和编织）将产生必要的统计数据，以最多约束此参数。
We study the evolution of the [Eu/Fe] ratio in the Galactic halo by means of a stochastic chemical evolution model considering merging neutron stars as polluters of europium. We improved our previous stochastic chemical evolution model by adding a time delay distribution for the coalescence of the neutron stars, instead of constant delays. The stochastic chemical evolution model can reproduce the trend and the observed spread in the [Eu/Fe] data with neutron star mergers as unique producers if we assume: i) a delay time distribution $\propto t^{-1.5}$, ii) a $M_{Eu}= 1.5$x$10^{-6} M_{\odot}$ per event, iii) progenitors of neutron stars in the range $9-50M_{\odot}$ and iv) a constant fraction of massive stars in the initial mass function (0.02) that produce neutron star mergers. Our best model is obtained by relaxing point iv) and assuming a fraction that varies with metallicity. We confirm that the mixed scenario with both merging neutron stars and supernovae as europium producers can provide a good agreement with the data relaxing the constraints on the distribution time delays for the coalescence of neutron stars. Adopting our best model, we also reproduce the dispersion of [Eu/Fe] at a given metallicity, which depends on the fraction of massive stars that produce neutron star mergers. Future high-resolution spectroscopic surveys, such as 4MOST and WEAVE, will produce the necessary statistics to constrain at best this parameter.
