Satellites around Milky Way Analogs: Tension in the Number and Fraction of Quiescent Satellites Seen in Observations versus Simulations
Satellites around Milky Way Analogs: Tension in the Number and Fraction of Quiescent Satellites Seen in Observations versus Simulations
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DOI：
10.3847/2041-8213/ac0e3a
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发表时间：
2021-05
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通讯作者：
A. Karunakaran;K. Spekkens;K. Oman;C. Simpson;Azadeh Fattahi;D. Sand;P. Bennet;D. Crnojevi'c;C. Frenk;F. G'omez;R. Grand;Michael G. Jones;F. Marinacci;B. Mutlu-Pakdil;J. Navarro;D. Zaritsky
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作者：
A. Karunakaran;K. Spekkens;K. Oman;C. Simpson;Azadeh Fattahi;D. Sand;P. Bennet;D. Crnojevi'c;C. Frenk;F. G'omez;R. Grand;Michael G. Jones;F. Marinacci;B. Mutlu-Pakdil;J. Navarro;D. Zaritsky
我们比较了银河系周围类似物调查(SAGA-II)第二阶段发布的银河系周围卫星(MW)的恒星形成特性，以及来自Apostle和Auriga宇宙放大模拟套件的类似物。我们使用档案GALEX UV成像作为SAGA-II样本的恒星形成指示器，并推导出恒星形成率(SFR)，以与Apostle和Auriga的恒星形成率(SFR)进行比较。我们将近紫外光和全紫外光波段的探测率与SAGA-II Hα探测进行了比较，发现它们与在所有三个示踪剂中检测到的85%以上的观测卫星大体一致。我们应用围绕SAGA-II主机使用的相同空间选择标准来选择Apostle和Auriga中类似MW的主机周围的卫星。我们发现，在观测和模拟样本中，所导出的恒星形成卫星的SFR以及每个主机的恒星形成卫星的数量在总体上是非常一致的。然而，即使考虑了SAGA-II的不完全性和入侵者修正，SAGA-II样本中猝灭的卫星的数量和比例也明显低于Apostle和Auriga的样本，其恒星质量低于M*∼108M⊙。这种差异在模拟的分辨率方面是稳健的，当使用替代恒星形成追踪器时，这种差异仍然存在。我们假设，这种不一致并不容易用这里考虑的观察或模拟样本中的反复无常来解释，这表明了真正的差异，可能会告知微波类似物周围的卫星群的物理学。
We compare the star-forming properties of satellites around Milky Way (MW) analogs from the Stage II release of the Satellites Around Galactic Analogs Survey (SAGA-ii) to those from the APOSTLE and Auriga cosmological zoom-in simulation suites. We use archival GALEX UV imaging as a star formation indicator for the SAGA-ii sample and derive star formation rates (SFRs) to compare with those from APOSTLE and Auriga. We compare our detection rates from the NUV and FUV bands to the SAGA-ii Hα detections and find that they are broadly consistent with over 85% of observed satellites detected in all three tracers. We apply the same spatial selection criteria used around SAGA-ii hosts to select satellites around the MW-like hosts in APOSTLE and Auriga. We find very good overall agreement in the derived SFRs for the star-forming satellites as well as the number of star-forming satellites per host in observed and simulated samples. However, the number and fraction of quenched satellites in the SAGA-ii sample are significantly lower than those in APOSTLE and Auriga below a stellar mass of M * ∼ 108 M ⊙, even when the SAGA-ii incompleteness and interloper corrections are included. This discrepancy is robust with respect to the resolution of the simulations and persists when alternative star formation tracers are employed. We posit that this disagreement is not readily explained by vagaries in the observed or simulated samples considered here, suggesting a genuine discrepancy that may inform the physics of satellite populations around MW analogs.