KAT-7的科学验证：利用HI观测NGC 3109了解其运动学和质量分布
KAT-7 Science Verification: Using HI Observations of NGC 3109 to Understand its Kinematics and Mass Distribution
摘要：
使用七碟卡鲁阵列望远镜（KAT-7）获得的麦哲伦型螺旋NGC 3109的HI观测结果用于分析其质量分布。我们的结果进行了比较，得到使用VLA数据。KAT-7是正在建造中的SKA探路者MeerKAT的前身。望远镜的短基线和低系统温度使其对大尺度低表面亮度发射敏感。KAT-7的新观测允许测量NGC 3109的旋转曲线到32 '，使现有测量的角度范围增加一倍。计算出HI的总质量为4.6 x 10^8 Msol，比VLA观测到的质量高出40%。观测驱动的伪等温暗物质（DM）晕模型可以很好地再现观测到的旋转曲线，但宇宙学驱动的NFW DM模型给出了一个更差的拟合数据。虽然有一个更准确的气体分布已经减少了观察到的RC和修改后的牛顿动力学（MOND）模型之间的差异，这是在不得不使用不切实际的质光比的恒星盘和/或非常大的值MOND通用常数a0的代价。不同的距离或HI含量不能使MOND与观察到的运动学一致，因为这两个量的误差很小。对于最近研究的许多缓慢旋转的富气星系，NGC 3109的当前结果继续对MOND理论构成严重挑战。
英文摘要：
HI observations of the Magellanic-type spiral NGC 3109, obtained with the seven dish Karoo Array Telescope (KAT-7), are used to analyze its mass distribution. Our results are compared to what is obtained using VLA data. KAT-7 is the precursor of the SKA pathfinder MeerKAT, which is under construction. The short baselines and low system temperature of the telescope make it sensitive to large scale low surface brightness emission. The new observations with KAT-7 allow the measurement of the rotation curve of NGC 3109 out to 32', doubling the angular extent of existing measurements. A total HI mass of 4.6 x 10^8 Msol is derived, 40% more than what was detected by the VLA observations. The observationally motivated pseudo-isothermal dark matter (DM) halo model can reproduce very well the observed rotation curve but the cosmologically motivated NFW DM model gives a much poorer fit to the data. While having a more accurate gas distribution has reduced the discrepancy between the observed RC and the MOdified Newtonian Dynamics (MOND) models, this is done at the expense of having to use unrealistic mass-to-light ratios for the stellar disk and/or very large values for the MOND universal constant a0. Different distances or HI contents cannot reconcile MOND with the observed kinematics, in view of the small errors on those two quantities. As for many slowly rotating gas-rich galaxies studied recently, the present result for NGC 3109 continues to pose a serious challenge to the MOND theory.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
