用观测到的星系旋转对抗冷暗物质预测
Confronting Cold Dark Matter Predictions with Observed Galaxy Rotations
摘要：
速度函数（VF）所捕获的星系旋转的丰富统计数据为星系重子物理和暗物质（DM）的性质提供了宝贵的约束。然而，将观测到的星系旋转与宇宙学模型进行比较容易产生微妙的警告，很容易导致误解。我们的分析揭示了在视线投影中观察到的~5000个星系旋转与基于标准宇宙学模型（LCDM）的千禧年模拟质量分辨率（HI线为基础的圆速度高于~50 km/s）的预测之间的完全统计一致性。解释，HI Parkes全天巡天（HIPASS）中的HI线宽与S3-SAX中的一致，S3-SAX是千禧年模拟的后处理半分析模型。以前发现的VF异常可以归因于（1）千禧年模拟的质量限制，（2）HIPASS中混乱的源，（3）光学微弱源的不准确倾斜测量，以及（4）缺乏气体的早期星系的不可探测性。这些问题可以通过使用线宽源计数而不是VF来比较观测和模型来绕过。我们调查，如果以及如何这样的源计数可以约束DM的温度。
英文摘要：
The rich statistics of galaxy rotations as captured by the velocity function (VF) provides invaluable constraints on galactic baryon physics and the nature of dark matter (DM). However, the comparison of observed galaxy rotations against cosmological models is prone to subtle caveats that can easily lead to misinterpretations. Our analysis reveals full statistical consistency between ~5000 galaxy rotations, observed in line-of-sight projection, and predictions based on the standard cosmological model (LCDM) at the mass-resolution of the Millennium simulation (HI line-based circular velocities above ~50 km/s). Explicitly, the HI linewidths in the HI Parkes All Sky Survey (HIPASS) are found consistent with those in S3-SAX, a post-processed semi-analytic model for the Millennium simulation. Previously found anomalies in the VF can be plausibly attributed to (1) the mass-limit of the Millennium simulation, (2) confused sources in HIPASS, (3) inaccurate inclination measurements for optically faint sources, and (4) the non-detectability of gas-poor early-type galaxies. These issues can be bypassed by comparing observations and models using linewidth source counts rather than VFs. We investigate if and how well such source counts can constrain the temperature of DM.
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