“NGC1052-DF2”的版本间差异

2019年3月29日 (五) 04:15的版本

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 arXiv:1810.04938 arXiv:1901.07586

测量误差很大，不能说得那么肯定 [2]
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,哪些星团已经并合了[3]
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） [4]
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 [5]

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 *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]]
 :*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�
+:* 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