Outflows from Super Star Clusters in the Central Starburst of NGC 253
Outflows from Super Star Clusters in the Central Starburst of NGC 253
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DOI：
10.3847/1538-4357/abec84
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发表时间：
2020-11
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通讯作者：
R. C. Levy;A. Bolatto;A. Leroy;K. Emig;M. Gorski;N. Krieger;L. Lenkić;D. Meier;E. Mills;J. Ott;E. Rosolowsky;E. Tarantino;S. Veilleux;F. Walter;A. Weiss;M. Zwaan
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作者：
R. C. Levy;A. Bolatto;A. Leroy;K. Emig;M. Gorski;N. Krieger;L. Lenkić;D. Meier;E. Mills;J. Ott;E. Rosolowsky;E. Tarantino;S. Veilleux;F. Walter;A. Weiss;M. Zwaan
年轻的大质量星系团在其宿主星系的演化中起着重要的作用，来自这些星系团中高质量恒星的反馈可以对周围的星际介质产生深远的影响。距离我们3.5 Mpc的星系NGC 253中的核星暴是研究极端环境下星星形成的关键实验室。之前来自阿塔卡马大型毫米/亚毫米阵列（阿尔马）的高分辨率（1.9 pc）尘埃连续观测发现了14个紧凑，大质量的超级星星团（SSC）仍在形成中。我们在这里提出的阿尔马数据在350 GHz的28 mas（0.5 pc）的分辨率。我们在多条谱线中检测到其中三个SSC的蓝移吸收和红移发射（P-Cygni谱线），包括CS 7−6和H13 CN 4−3，这代表了以前未观察到的流出的直接证据。这些流出物中包含的质量占团簇气体质量的很大一部分，这表明我们正在目睹一个短暂但重要的阶段。这方面的进一步证据是在近红外波长下可见的唯一SSC周围发现了分子壳。我们模拟的P-Cygni线轮廓，以约束流出的几何形状，发现流出必须是近球形的。通过对外流特性与模拟预测的比较，我们发现没有一种可用的机制完全解释了观测结果，尽管尘埃再处理辐射压和O星星风是最有可能的候选者。观测到的外流将对星团的演化和星星形成效率产生非常重要的影响。
Young massive clusters play an important role in the evolution of their host galaxies, and feedback from the high-mass stars in these clusters can have profound effects on the surrounding interstellar medium. The nuclear starburst in the nearby galaxy NGC 253 at a distance of 3.5 Mpc is a key laboratory in which to study star formation in an extreme environment. Previous high-resolution (1.9 pc) dust continuum observations from the Atacama Large Millimeter/submillimeter Array (ALMA) discovered 14 compact, massive super star clusters (SSCs) still in formation. We present here ALMA data at 350 GHz with 28 mas (0.5 pc) resolution. We detect blueshifted absorption and redshifted emission (P-Cygni profiles) toward three of these SSCs in multiple lines, including CS 7−6 and H13CN 4−3, which represent direct evidence for previously unobserved outflows. The mass contained in these outflows is a significant fraction of the cluster gas masses, which suggests we are witnessing a short but important phase. Further evidence of this is the finding of a molecular shell around the only SSC visible at near-IR wavelengths. We model the P-Cygni line profiles to constrain the outflow geometry, finding that the outflows must be nearly spherical. Through a comparison of the outflow properties with predictions from simulations, we find that none of the available mechanisms completely explains the observations, although dust-reprocessed radiation pressure and O star stellar winds are the most likely candidates. The observed outflows will have a very substantial effect on the clusters’ evolution and star formation efficiency.