“NGC1052-DF2”的版本间差异

来自Shiyin's note
跳到导航 跳到搜索
无编辑摘要
无编辑摘要
第2行： 第2行：


==观测==
==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.
*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.
*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
*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
*气体含量非常低 arXiv:1810.04938 arXiv:1901.07586


==模型==
==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]
*really
:*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,哪些星团已经并合了[https://arxiv.org/abs/1806.01812]
:*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]
*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 ]
:*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
*MOND

2019年3月29日 (五) 04:19的版本

  • 号称没有暗物质的星系, ultra diffuse galaxy [1] Nature March 2018
    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 arXiv:1810.04938 arXiv: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 [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]
  • MOND
  • 不支持MOND，弱引力场（近似于有暗物质）[6]
  • 你没考虑NGC1052作用，符合MOND！ [7] Nature March 2019
  • NGC1052-DF4， same group，第二个号称没有暗物质的星系 [8]（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=3058”