“NGC1052-DF2”的版本间差异

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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]]
*号称没有暗物质的星系
:气体含量非常低 arXiv:1810.04938 arXiv:1901.07586
:NGC1052-DF4, same group,第二个号称没有暗物质的星系 arXiv:1901.05973 (球状星团算的速度弥散度)


==观测==
*如果有暗物质,这些球状星团系统受到暗物质的dynamic friction,会形成nuclear cluster[arXiv:1902.05959 ]
*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==
* [[https://arxiv.org/abs/1903.11612 | 1903.11612]] Nature 文章:动力学符合MOND
*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]

----
* 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)

2020年10月18日 (日) 12:24的最新版本

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 [2] [3]

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 [4]
  • 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[5]
  • 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) [6]
  • 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 [7]
  • MOND
  • 不支持MOND,弱引力场(近似于有暗物质)[8]
  • 你没考虑NGC1052作用,符合MOND! [9] Nature March 2019

结局

  • 你们距离算错了 [10]

  • NGC1052-DF4, same group,第二个号称没有暗物质的星系 [11](还是球状星团算的速度弥散度)