Cuspy dark matter density profiles in massive dwarf galaxies
Cuspy dark matter density profiles in massive dwarf galaxies
复制标题
大质量矮星系中的尖点暗物质密度分布
DOI：
10.1093/mnras/stac588
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发表时间：
2022
影响因子：
4.8
通讯作者：
Lenkić, Laura
中科院分区：
文献类型：
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作者：
Cooke, Lauren H.;Levy, Rebecca C.;Bolatto, Alberto D.;Simon, Joshua D.;Newman, Andrew B.;Teuben, Peter;Davey, Brandon D.;Wright, Melvyn;Tarantino, Elizabeth;Lenkić, Laura
星系的自转曲线可以探测它们的总质量分布，包括暗物质。矮星系是研究暗物质密度分布的绝佳系统，因为与更高质量的系统相比，它们往往具有更大比例的暗物质。核心尖点问题描述了在矮星系（较浅的核心）和仅暗物质模拟（较陡的尖点）之间观测到的星系中心暗物质密度分布（β*）的斜率差异。利用阿尔马（Atacama Large Millimeter/Submillimeter Array）获得的高分辨率COJ= 1-0数据，研究了六个邻近旋涡矮星系的β*。我们推导出旋转曲线和分解的质量配置文件的暗物质使用我们的CO旋转曲线作为示踪剂的总潜力和4.5米测光定义恒星的质量分布。我们发现，在这个样本中的星系中，α β* α = 0.6，标准差为±0.1，与以前在这个质量范围内的测量结果一致。研究的星系是在矮星系的高恒星质量端，并具有比低质量的矮星，在协议与其他意见的cuspier配置文件。当使用相同的斜率定义时，我们观察到比FIRE和NIHAO模拟预测的斜率更陡的斜率。这可能表明，这些相对较大的矮星经历了比这些模拟预测的更强的气体流入它们的中心，这些模拟过度预测了吸积或反馈事件的频率，或者这些或其他效应的组合正在起作用。
Rotation curves of galaxies probe their total mass distributions, including dark matter. Dwarf galaxies are excellent systems to investigate the dark matter density distribution, as they tend to have larger fractions of dark matter compared to higher mass systems. The core-cusp problem describes the discrepancy found in the slope of the dark matter density profile in the centres of galaxies (β*) between observations of dwarf galaxies (shallower cores) and dark matter-only simulations (steeper cusps). We investigate β* in six nearby spiral dwarf galaxies for which high-resolution COJ= 1–0 data were obtained with ALMA (Atacama Large Millimeter/submillimeter Array). We derive rotation curves and decompose the mass profile of the dark matter using our CO rotation curves as a tracer of the total potential and 4.5m photometry to define the stellar mass distribution. We find 〈β*〉 = 0.6 with a standard deviation of ±0.1 among the galaxies in this sample, in agreement with previous measurements in this mass range. The galaxies studied are on the high stellar mass end of dwarf galaxies and have cuspier profiles than lower mass dwarfs, in agreement with other observations. When the same definition of the slope is used, we observe steeper slopes than predicted by the FIRE and NIHAO simulations. This may signal that these relatively massive dwarfs underwent stronger gas inflows towards their centres than predicted by these simulations, that these simulations overpredict the frequency of accretion or feedback events, or that a combination of these or other effects are at work.