Effects of the integrated galactic IMF on the chemical evolution of the solar neighbourhood
Effects of the integrated galactic IMF on the chemical evolution of the solar neighbourhood
复制标题
综合星系 IMF 对太阳邻域化学演化的影响
DOI：
10.1111/j.1365-2966.2010.16803.x
复制
发表时间：
2010
影响因子：
4.8
通讯作者：
B. University
中科院分区：
文献类型：
--
作者：
F. Calura;S. Recchi;F. Matteucci;P. Kroupa;D. Astronomia;U. Trieste;Inaf Trieste;I. O. Astronomy;V. University;Argelander Institute for Astronomy;B. University
初始质量函数决定了每一代恒星产生不同初始质量的恒星的比例。本文检验了积分星系初始质量函数(IGIMF)对太阳近邻化学演化的影响。IGIMF(Weidner&Kroupa2005)是由恒星初始质量函数(即单星团的质量函数)和嵌入的星团质量函数(即指数为β的幂定律)的组合计算得出的。考虑到最大可达恒星质量是星团总质量的函数这一事实，IGIMF变成了一个依赖于恒星形成率的时变IMF。我们将这种形式应用于太阳近邻的化学演化模型，并将假设三个可能的β值所获得的结果与通过标准的、经过充分测试的恒定IMF所获得的结果进行了比较。一般来说，β的绝对值越低，意味着IGIMF越平坦，因此有更多的大质量恒星和更大的金属抛射率。这意味着更高的Ia型和II型超新星速率，大质量恒星的质量抛射率和可用于恒星形成的更多气体，加上当今较低的恒星质量密度。在给定的金属丰度下，较低的β值也对应较高的金属度和较高的[α/Fe]值。我们考虑了一大组化学演化可观测数据，并测试β的哪个值提供了与所有这些约束最匹配的值。我们还讨论了现在的恒星质量函数的重要性，它为β提供了一种解决各种假设的方法。我们的结果表明，采用β�2计算的IGIMF的模型应该被认为是最好的，因为它允许我们再现观察到的PDMF，并解释了本工作中考虑的大部分化学演化约束。
The initial mass function determines the fraction of stars of different initial mass born per stellar generation. In this paper, we test the effects of the integrated galactic initial mass function (IGIMF) on the chemical evolution of the solar neighbourhood. The IGIMF (Weidner & Kroupa 2005) is computed from the combination of the stellar initial mass function (IMF), i.e. the mass function of single star clusters, and the embedded cluster mass function, i.e. a power law with index β. By taking into account also the fact that the maximum achievable stellar mass is a function of the total mass of the cluster, the IGIMF becomes a time-varying IMF which depends on the star formation rate. We applied this formalism to a chemical evolution model for the solar neighbourhood and compared the results obtained by assuming three possible values for β with the results obtained by means of a standard, well-tested, constant IMF. In general, a lower absolute value of β implies a flatter IGIMF, hence a larger number of massive stars and larger metal ejection rates. This translates into higher type Ia and II supernova rates, higher mass ejection rates from massive stars and a larger amount of gas available for star formation, coupled with lower present-day stellar mass densities. Lower values of β correspond also to higher metallicities and higher [α/Fe] values at a given metallicity. We consider a large set of chemical evolution observables and test which value of β provides the best match to all of these constraints. We also discuss the importance of the present-day stellar mass function (PDMF) in providing a way to disentangle among various assumptions for β. Our results indicate that the model adopting the IGIMF computed with β � 2 should be considered the best since it allows us to reproduce the observed PDMF and to account for most of the chemical evolution constraints considered in this work.
关于郊区的星团形成和物质吸积
DOI：
--
发表时间：
2018
期刊：
影响因子：
--
作者：
九後太一;藤田裕
通讯作者：
藤田裕