查看“NGC1052-DF2”的源代码

*号称没有暗物质的星系, [[ultra diffuse galaxy]] [https://arxiv.org/abs/1803.10237] '''Nature March 2018''' [[文件:NGC1052-DF2.JPG|缩略图|HST/ACS image]]

==观测==
*S´ersic index  n = 0.6,  axis ratio  b/a = 0.85, the central surface brightness is µ(V606,0) = 24.4magarcsec−2, D=20Mpc.
* effective radius along the major axis is Re = 2.2kpc,  M606 = −15.4 mag, Mstars ≈ 2×10^8 Msun.
*an extraordinary population of globular clusters, larger and more luminous than average GCs in the Milky Way,  total mass is roughly 4 percent of the mass in stars, making DF2 one of the galaxies with the largest speciﬁc frequencies known. 
*the line-of-sight velocity dispersion of the GCs(10km/s) suggests a total dynamical mass for DF2 that leaves little room for any dark matter
*气体含量非常低 [https://arxiv.org/abs/1810.04938] [https://arxiv.org/abs/1901.07586]

==模型==
*测量误差很大，如果有些球状星团是背景，不能说得那么肯定 [https://arxiv.org/abs/1804.04136]
*如果没有暗物质，星系和球状星团质量的比靠近，动力学摩擦效应显著（时标1-2Gyr）,大部分星团团已经被并合了[https://arxiv.org/abs/1806.01812] 
*考虑NGC1052的tidal效应，改变了DF2中球状星团在相空间的分布函数 （真实空间外围的GC少了，GC在速度空间的弥散小了）  [https://arxiv.org/abs/1810.03864]
*没有暗物质的dynamical friction没那么简单,  core-stalling and GC-GC interactions效应, 让星团掉不进去。反过来，如果有cuspy的NFW暗晕，里面的dynamical friction更强，会形成核心GC [https://arxiv.org/abs/1902.05959 ]

*MOND
:*不支持MOND，弱引力场（近似于有暗物质）[https://arxiv.org/abs/1804.04167]
:*你没考虑NGC1052作用，符合MOND！  [https://arxiv.org/abs/1903.11612]  '''Nature March 2019'''

==结局==
*你们距离算错了 [https://arxiv.org/abs/1806.10141]

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* NGC1052-DF4， same group，第二个号称没有暗物质的星系  [https://arxiv.org/abs/1901.05973]（还是球状星团算的速度弥散度）