We use magneto-hydrodynamical simulations of Milky Way-mass haloes from the Auriga project to examine the properties of surviving and destroyed dwarf galaxies that are accreted by these haloes over cosmic time. We show that the combined luminosity function of surviving and destroyed dwarfs at infall is similar in the various Auriga haloes, and is dominated by the destroyed dwarfs. There is, however, a strong dependence on infall time: destroyed dwarfs have typically early infall times, $t_{infall} 10$ Gyr have survived to the present day. Because of their late infall the surviving satellites today had higher metallicites at infall than their destroyed counterparts of similar infall mass; the difference is even more pronounced for the present-day metallicites of satellites, many of which continue to form stars after infall. In agreement with previous work, we find that a small number of relatively massive destroyed dwarf galaxies dominate the mass of the stellar haloes. However, there is a significant radial dependence: while 90 per cent of the mass in the inner regions ($ \,100\,$kpc) typically have $\sim8$ main progenitors of relatively lower mass. Finally, we show that a few massive progenitors dominate the metallicity distribution of accreted stars, even at the metal poor end. Contrary to common assumptions in the literature, dwarf galaxies of mass $M_{*}<10^7 \, M_{\odot}$ make up less than 10 per cent of the accreted, metal poor stars ([Fe/H] $<\,-3$) in the inner $50\,$kpc.

中文翻译：

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两个族群的故事：幸存和毁灭的矮星系以及银河系恒星晕的形成

我们使用来自御夫座项目的银河系质量晕的磁流体动力学模拟来检查在宇宙时间内由这些晕增加的幸存和被摧毁的矮星系的特性。我们表明，在各种御夫座光环中，幸存的和被摧毁的矮星在坠落时的综合光度函数是相似的，并且以被摧毁的矮星为主。然而，对坠落时间有很强的依赖性：被摧毁的矮人通常有较早的坠落时间，$t_{infall} 10$ Gyr 存活至今。由于它们下落较晚，今天幸存的卫星在下落时的金属矿含量高于它们被摧毁的同等质量的卫星。对于当今的卫星金属矿来说，这种差异甚至更加明显，其中许多卫星在落入后继续形成恒星。与之前的工作一致，我们发现少数相对质量较大的被摧毁的矮星系主宰了恒星晕的质量。然而，存在显着的径向依赖性：虽然内部区域 ($\,100\,$kpc) 中 90% 的质量通常具有质量相对较低的 $\sim8$ 主要祖先。最后，我们表明即使在金属贫乏端，一些大质量的前身星也支配着吸积星的金属丰度分布。与文献中的普遍假设相反，质量为 $M_{*}<10^7 \, M_{\odot}$ 的矮星系占吸积的贫金属恒星（[Fe/H] $ <\,-3$) 在内部 $50\,$kpc 中。而内部区域 ($\,100\,$kpc) 中 90% 的质量通常具有质量相对较低的 $\sim8$ 主要祖先。最后，我们表明即使在金属贫乏端，一些大质量的前身星也支配着吸积星的金属丰度分布。与文献中的普遍假设相反，质量为 $M_{*}<10^7 \, M_{\odot}$ 的矮星系占吸积的贫金属恒星（[Fe/H] $ <\,-3$) 在内部 $50\,$kpc 中。而内部区域 ($\,100\,$kpc) 中 90% 的质量通常具有质量相对较低的 $\sim8$ 主要祖先。最后，我们表明即使在金属贫乏端，一些大质量的前身星也支配着吸积星的金属丰度分布。与文献中的普遍假设相反，质量为 $M_{*}<10^7 \, M_{\odot}$ 的矮星系占吸积的贫金属恒星（[Fe/H] $ <\,-3$) 在内部 $50\,$kpc 中。