极端星系分析：MAGNETICUM模拟中的失败星系前身
Analysis of Galaxies at the Extremes: Failed Galaxy Progenitors in the MAGNETICUM Simulations
AI总结：
本研究利用MAGNETICUM模拟识别出443个高红移失败星系前身候选体，发现其具有平坦核暗晕、延展恒星体、外围气体、低金属丰度及高恒星形成率等特征，并预测其比例随环境密度增加。
摘要：
越来越多的观测证据表明，在低红移下，一些超弥散星系（UDGs）存在一条失败星系形成路径，但目前缺乏对应的模拟样本。我们试图在MAGNETICUM宇宙学模拟中识别高红移下的暗物质晕，这些暗物质晕可能是它们的合理前身。我们构建了一个在恒星质量-暗物质晕质量关系内的被动星系演化玩具模型，将z = 0的UDG观测追溯回其z = 2的位置。我们在模拟中识别出443个符合这些参数空间位置的星系。我们在模拟中构建了两个比较样本，它们遵循z = 2时的恒星质量-暗物质晕质量关系，其中一个样本与我们的样本恒星质量匹配（具有不同的较小暗物质晕质量），另一个样本与我们的样本暗物质晕质量匹配（具有不同的较大恒星质量）。我们识别出，我们的失败星系前身候选体具有：1）更平坦、带核的暗物质晕；2）更延展的恒星主体；3）其气体中有更大比例位于暗物质晕的外围；4）更低的金属丰度；以及5）比对照样本更高的恒星形成率。发现1）和2）与低红移UDG的观测相似。发现3）将有助于气体的移除和恒星形成的永久性熄灭，这是失败星系形成情景的一个要求。发现4）的低金属丰度与低红移失败星系UDG中观测到的结果相符。将发现5）的高恒星形成率与近期JWST观测进行比较，表明恒星暴发可以自然地解释UDG的高球状星团丰富度。我们发现的这些失败星系前身的许多特性可以通过其暗物质晕向更晚形成时间的组装偏置来解释。我们最后提出，失败星系UDG的比例预计会随着环境密度的增加而增加。
英文摘要：
There is increasing observational evidence for a failed galaxy formation pathway for some ultradiffuse galaxies (UDGs) at low redshift however they currently lack simulated counterparts. We attempt to identify dark matter halos at high redshift within the MAGNETICUM cosmological simulations that could plausibly be their progenitors. We build a toy model of passive galaxy evolution within the stellar mass-halo mass relation to trace z = 0 observations of UDGs back to their z = 2 locations. We identify a population of 443 galaxies that match these parameter space positions within the simulation. We build two comparison samples within the simulation that follow the stellar mass-halo mass relationship at z = 2, one of which is stellar mass matched (with varying smaller halo masses) and the other is halo mass matched (with varying larger stellar masses) to our sample. We identify that our failed galaxy progenitor candidates have 1) flatter, cored dark matter halos; 2) more extended stellar bodies; 3) a larger fraction of their gas in the outskirts of their halos; 4) lower metallicities and 5) higher star formation rates than the control samples. Findings 1) and 2) are similar to low redshift observations of UDGs. Finding 3) will aid the removal of gas and permanent quenching of star formation which is a requirement of the failed galaxy formation scenario. The low metallicities of finding 4) match those observed in low redshift failed galaxy UDGs. Comparing the high star formation rates of finding 5) to recent JWST observations suggests that a starburst would naturally explain the high globular cluster richness of the UDGs. Many of the properties we find for these failed galaxy progenitors can be explained by an assembly bias of their dark matter halo to later formation times. We conclude by proposing that the fraction of failed galaxy UDGs is expected to increase with environmental density.
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