标题： 来自几乎暗弱星系的发射线点和极金属缺乏矮星的形成 显示英文标题

标题： Formation of emission line dots and extremely metal-deficient dwarfs from almost dark galaxies

摘要： 近期的观测发现了一些非常富气且极为暗弱的矮星系，它们可能嵌套在低质量暗物质晕中。 我们研究了这些富气矮星系（“几乎黑暗”的星系）的恒星形成历史，包括孤立情况以及相互作用/合并的情况。 我们发现，尽管对于总晕质量 \( M_h \) 在 \( 10^8-10^9 M_\odot \) 的孤立模拟矮星系而言，恒星形成率（SFRs）非常低（< \( 10^\{-5\} M_\odot / \text\{yr\} \)），但在它们与其他矮星系相互作用或合并时，可以显著增加到约 \( 10^\{{-4}\} M_\odot / \text\{yr\} \)。 这些相互作用的微弱矮星系由于古老恒星非常低的表面亮度包层，其中心紧凑的HII区域可以被识别为孤立的发射线点（"ELdots"）。 这些相互作用和合并矮星系的残骸最终会发展出具有极低金属丰度（\( Z/Z_\odot < 0.1 \)）的中心紧凑恒星系统，可被识别为极端金属缺乏（"XMD"）矮星系。 这些结果表明，虽然当前光学观测中可能存在许多难以探测到的微弱矮星系，但当它们与其他星系及其宿主环境相互作用时，可以通过孤立的ELdots或XMD矮星系的形式被探测到。 我们预测，由几乎黑暗的矮星系合并形成的核球超微弱矮星系，由于其非常低的表面亮度恒星包层，如果它们是遥远的天体，可以被识别为球状星团。 显示英文摘要

摘要： Recent observations have discovered a number of extremely gas-rich very faint dwarf galaxies possibly embedded in low-mass dark matter halos. We investigate star formation histories of these gas-rich dwarf ("almost dark") galaxies both for isolated and interacting/merging cases. We find that although star formation rates (SFRs) are very low (<10^-5 M_sun/yr) in the simulated dwarfs in isolation for the total halo masses (M_h) of 10^8-10^9 M_sun, they can be dramatically increased to be ~ 10^{-4} M_sun/yr when they interact or merge with other dwarfs. These interacting faint dwarfs with central compact HII regions can be identified as isolated emission line dots ("ELdots") owing to their very low surface brightness envelopes of old stars. The remnant of these interacting and merging dwarfs can finally develop central compact stellar systems with very low metallicities (Z/Z_sun<0.1), which can be identified as extremely metal-deficient ("XMD") dwarfs. These results imply that although there would exist many faint dwarfs that can be hardly detected in the current optical observations, they can be detected as isolated ELdots or XMD dwarfs, when they interact with other galaxies and their host environments. We predict that nucleated ultra-faint dwarfs formed from merging of almost dark dwarfs can be identified as globular clusters owing to the very low surface brightness stellar envelopes, if they are distant objects.