用真实恒星光谱修正H $_2$和H $^-$的破坏速率系数
Revised rate coefficients for H$_2$ and H$^-$ destruction by realistic stellar spectra
摘要：
了解能够摧毁H $_2$和H $^-$物种的过程是控制第一批恒星、黑洞和星系形成的精髓。在这项研究中，我们计算的反应速率系数H $_2$光解离莱曼-沃纳光子（$11.2 - 13.6$ eV），和H $^-$光-脱离0.76 eV的光子从自洽的恒星群体，我们使用公开可用的恒星合成代码模型。到目前为止，包括分子氢形成的化学网络的研究通过假设源光谱可以近似为幂律依赖性或在10 $^4$或$10^5$ K下的黑体光谱来考虑这些过程。我们表明，使用光谱产生的真实的恒星人口模型可以改变的反应速率的光解离，$\rm k_{\rm{di}}$，和光剥离，$\rm k_{\rm{de}}$，显着。特别是，$\rm k_{\rm{de}}$可以高达$\sim 2-4$的数量级低的情况下，现实的恒星光谱表明，以前的计算高估了辐射的影响，降低H $_2$丰度。与恒星形成的爆发模式相反，我们发现，连续恒星形成的模型预测增加$\rm k_{\rm{de}}$和$\rm k_{\rm{di}}$，这使得有必要包括恒星形成的历史来源，以获得自洽的反应速率，这是不够的，只是计算J $_{21}$的背景。对于恒星形成速率恒定的模型，光谱能量分布形状的变化导致了不可忽略的晚时贡献$\rm k_{\rm{de}}$和$\rm k_{\rm{di}}$，我们提出了自洽导出的宇宙学反应速率的恒星形成速率的基础上一致的观测高红移宇宙。
英文摘要：
Understanding the processes that can destroy H$_2$ and H$^-$ species is quintessential in governing the formation of the first stars, black holes and galaxies. In this study we compute the reaction rate coefficients for H$_2$ photo--dissociation by Lyman--Werner photons ($11.2 - 13.6$ eV), and H$^-$ photo--detachment by 0.76 eV photons emanating from self-consistent stellar populations that we model using publicly available stellar synthesis codes. So far studies that include chemical networks for the formation of molecular hydrogen take these processes into account by assuming that the source spectra can be approximated by a power-law dependency or a black-body spectrum at 10$^4$ or $10^5$ K. We show that using spectra generated from realistic stellar population models can alter the reaction rates for photo-dissociation, $\rm k_{\rm{di}}$, and photo-detachment, $\rm k_{\rm{de}}$, significantly. In particular, $\rm k_{\rm{de}}$ can be up to $\sim 2-4$ orders of magnitude lower in the case of realistic stellar spectra suggesting that previous calculations have over-estimated the impact that radiation has on lowering H$_2$ abundances. In contrast to burst modes of star formation, we find that models with continuous star formation predict increasing $\rm k_{\rm{de}}$ and $\rm k_{\rm{di}}$, which makes it necessary to include the star formation history of sources to derive self-consistent reaction rates, and that it is not enough to just calculate J$_{21}$ for the background. For models with constant star formation rate the change in shape of the spectral energy distribution leads to a non-negligible late-time contribution to $\rm k_{\rm{de}}$ and $\rm k_{\rm{di}}$, and we present self-consistently derived cosmological reaction rates based on star formation rates consistent with observations of the high redshift Universe.
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