“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, [[ultra diffuse galaxy]] [https://arxiv.org/abs/1803.10237] '''Nature March 2018''' [[文件:NGC1052-DF2.JPG|缩略图|HST/ACS image]]
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:*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.
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:* effective radius along the major axis is Re = 2.2kpc, M606 = −15.4 mag, Mstars ≈ 2×10^8 Msun.
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:*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.
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:*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
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:*气体含量非常低 arXiv:1810.04938 arXiv:1901.07586


==观测==
* really?
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*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.
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:*测量误差很大，不能说得那么肯定 [https://arxiv.org/abs/1804.04136]
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* effective radius along the major axis is Re = 2.2kpc, M606 = −15.4 mag, Mstars ≈ 2×10^8 Msun.
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:*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[https://arxiv.org/abs/1806.01812]
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*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.
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:*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]
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*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
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:*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 ]
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*气体含量非常低 [https://arxiv.org/abs/1810.04938] [https://arxiv.org/abs/1901.07586]


==模型==
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* MOND
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*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]
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*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 ]

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*MOND
:*不支持MOND，弱引力场（近似于有暗物质）[https://arxiv.org/abs/1804.04167]
:*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'''
:*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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----

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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）
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---

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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/901.05973]（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）
取自“http://202.127.29.3/~shen/wiki/index.php?title=NGC1052-DF2&oldid=3322”