Dwarf galaxy rotation curves and the core problem of dark matter haloes
Dwarf galaxy rotation curves and the core problem of dark matter haloes
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DOI：
10.1046/j.1365-8711.2001.04456.x
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发表时间：
2000-06
影响因子：
4.8
通讯作者：
F. V. D. Bosch;R. Swaters
中科院分区：
文献类型：
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作者：
F. V. D. Bosch;R. Swaters
ABSTRA C T标准的冷暗物质（CDM）模型最近受到了矮星系具有恒定密度核心的暗物质晕的说法的挑战，而CDM预测的晕具有陡峭的尖形密度分布。因此，最近提出了许多替代的暗物质候选者。在本文中，我们仔细检查矮星系和CDM模型之间的不协调的观测证据。为此，我们分析了Swaters研究的20个晚型矮星系的自转曲线。考虑到束流拖尾和绝热收缩的影响，我们拟合质量模型，这些旋转曲线与暗物质晕不同的尖点斜率，范围从恒定密度核心r 22尖点。尽管光束拖尾对这些数据的影响很小，但恒星质光比的不确定性和晕密度分布的有限空间采样阻碍了独特的质量分解。因此，在我们的样本中的旋转曲线不能用来区分暗晕与恒定密度的核心和r 21尖点。我们表明，在这里分析的矮星系是一致的CDM晕在LCDM宇宙学，因此没有必要放弃的想法，暗物质是冷的和碰撞。然而，这些数据也与任何其他暗物质模型相一致，这些模型产生的暗物质晕的中心尖点比r21.5更陡。事实上，我们认为，仅根据现有的H I旋转曲线，最好的弱限制可以得到宇宙学参数和/或暗物质的性质。为了取得进展，需要具有更高空间分辨率的旋转曲线和对光盘的质光比的独立测量。
ABSTRA C T The standard cold dark matter (CDM) model has recently been challenged by the claim that dwarf galaxies have dark matter haloes with constant-density cores, whereas CDM predicts haloes with steeply cusped density distributions. Consequently, numerous alternative dark matter candidates have recently been proposed. In this paper we scrutinize the observational evidence for the incongruity between dwarf galaxies and the CDM model. To this end, we analyse the rotation curves of 20 late-type dwarf galaxies studied by Swaters. Taking the effects of beam smearing and adiabatic contraction into account, we fit mass models to these rotation curves with dark matter haloes with different cusp slopes, ranging from constantdensity cores to r 22 cusps. Even though the effects of beam smearing are small for these data, the uncertainties in the stellar mass-to-light ratio and the limited spatial sampling of the halo’s density distribution hamper a unique mass decomposition. Consequently, the rotation curves in our sample cannot be used to discriminate between dark haloes with constant-density cores and r 21 cusps. We show that the dwarf galaxies analysed here are consistent with CDM haloes in a LCDM cosmology, and that there is thus no need to abandon the idea that dark matter is cold and collisionless. However, the data are also consistent with any alternative dark matter model that produces dark matter haloes with central cusps less steep than r 21.5 . In fact, we argue that based on existing H I rotation curves alone, at best weak limits can be obtained on cosmological parameters and/or the nature of the dark matter. In order to make progress, rotation curves with higher spatial resolution and independent measurements of the mass-to-light ratio of the disc are required.