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arXiv 1611.01409astro-ph.GAastro-ph.CO
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M33中暗物质分布的径向依赖性

The radial dependence of dark matter distribution in M33

Ernesto López Fune, Paolo Salucci, Edvige Corbelli

摘要:

利用附近星系M33的恒星和气体质量分布以及扩展的自转曲线,导出了晕中暗物质密度的径向分布,并检验了星系形成和演化的宇宙学模型。研究了两种方法来约束暗质量密度分布。第一种方法直接处理拟合的旋转曲线数据的范围内的银河系的距离$0.24\,\text{kpc}\leq r\leq22.72\,\text{kpc}.$如发现在以前的论文\citet{Corbelli:2014lga},并使用碰撞$Λ-$冷暗物质数值模拟的结果,我们确认,Navarro-Frenkel-White(以下简称NFW)暗物质配置文件提供了一个更好的拟合旋转曲线数据比核心Burkert配置文件(以下简称BRK)的配置文件。第二种方法依赖于离心平衡的局部方程和旋转曲线斜率。在上述距离范围内,我们使用一个与半径有合理关系的函数来拟合观测到的速度分布,并推导出旋转曲线的斜率。在\citet{Salucci:2010qr}之后,我们推断有效物质密度。在$9.53\,\text{kpc}\leq r\leq22.72\,\text{kpc}$的径向范围内,由发光物质(恒星和气体)引起的不确定性变得可以忽略不计,因为暗物质密度占主导地位,我们可以确定局部的暗物质的径向分布。使用第二种方法,我们测试了NFW和BRK暗物质的剖面,并确认这两个剖面与数据是相容的,即使在这种情况下,核心BRK密度剖面提供了一个更合理的重子-暗物质比。

英文摘要:

The stellar and gaseous mass distributions, as well as the extended rotation curve in the nearby galaxy M33 are used to derive the radial distribution of dark matter density in the halo and to test cosmological models of galaxy formation and evolution. Two methods are examined to constrain dark mass density profiles. The first method deals directly with fitting the rotation curve data in the range of galactocentric distances $0.24\,\text{kpc}\leq r\leq22.72\,\text{kpc}.$ As found in a previous paper by \citet{Corbelli:2014lga}, and using the results of collisionless $Λ-$Cold Dark Matter numerical simulations, we confirm that the Navarro-Frenkel-White (hereafter NFW) dark matter profile provides a better fit to the rotation curve data than the cored Burkert profile (hereafter BRK) profile. The second method relies on the local equation of centrifugal equilibrium and on the rotation curve slope. In the aforementioned range of distances we fit the observed velocity profile, using a function which has a rational dependence on the radius, and derive the slope of the rotation curve. Following \citet{Salucci:2010qr} we then infer the effective matter densities. In the radial range $9.53\,\text{kpc}\leq r\leq22.72\,\text{kpc}$ the uncertainties induced by the luminous matter (stars and gas) becomes negligible, because the dark matter density dominates, and we can determine locally the radial distribution of dark matter. With this second method we tested the NFW and the BRK dark matter profiles and confirm that both profiles are compatible with the data even though in this case the cored BRK density profile provides a more reasonable value for the baryonic-to-dark matter ratio.

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