Title: The insight into the dark side. I. The pitfalls of the dark halo parameters estimation Show Chinese title

Title: 对暗面的洞察。 I. 暗晕参数估计的陷阱

Abstract: We examined the reliability of estimates of pseudoisothermal, Burkert and NFW dark halo parameters for the methods based on the mass-modelling of the rotation curves.To do it we constructed the $\chi^2$ maps for the grid of the dark matter halo parameters for a sample of 14 disc galaxies with high quality rotation curves from THINGS. We considered two variants of models in which: a) the mass-to-light ratios of disc and bulge were taken as free parameters, b) the mass-to-light ratios were fixed in a narrow range according to the models of stellar populations. To reproduce the possible observational features of the real galaxies we made tests showing that the parameters of the three halo types change critically in the cases of a lack of kinematic data in the central or peripheral areas and for different spatial resolutions. We showed that due to the degeneracy between the central densities and the radial scales of the dark haloes there are considerable uncertainties of their concentrations estimates. Due to this reason it is also impossible to draw any firm conclusion about universality of the dark halo column density based on mass-modelling of even a high quality rotation curve. The problem is not solved by fixing the density of baryonic matter. In contrast, the estimates of dark halo mass within optical radius are much more reliable. We demonstrated that one can evaluate successfully the halo mass using the pure best-fitting method without any restrictions on the mass-to-light ratios. Show Chinese abstract

Abstract: 我们检查了基于旋转曲线质量建模方法的伪等温、Burkert 和 NFW 暗晕参数估计的可靠性。为了做到这一点，我们为一个包含 14 个具有高质量旋转曲线的盘星系样本的暗物质晕参数网格构建了$\chi^2$图。 我们考虑了两种模型变体，其中：a) 盘和核球的质量光度比被作为自由参数，b) 质量光度比根据恒星种群模型在狭窄范围内固定。 为了再现真实星系可能的观测特征，我们进行了测试，结果显示，在中心或外围区域缺乏运动学数据以及不同空间分辨率的情况下，三种晕类型的参数会发生显著变化。 我们表明，由于暗晕中心密度与径向尺度之间的退化，它们的浓度估计存在较大的不确定性。 由于这个原因，即使基于高质量的旋转曲线质量建模，也无法得出关于暗晕柱密度普遍性的任何确定结论。 通过固定重子物质密度并不能解决这个问题。 相反，光学半径内的暗晕质量估计要可靠得多。 我们证明可以成功地使用纯粹的最佳拟合方法来评估晕质量，而无需对质量光度比施加任何限制。