arXiv 1806.095912018-06astro-ph.GAastro-ph.CO

天炉座有核心光环吗对暗物质性质的暗示

Does Fornax have a cored halo? Implications for the nature of dark matter

P. Boldrini, R. Mohayaee, J. Silk

备注：: Substituted by a new paper using much higher resolution simulation with different initial conditions on dark matter halos entitled: Fornax globular cluster distributions: implications for the cusp-core problem and same authors (arXiv:1903.00354)

摘要：

天炉座是银河系中质量最大的矮球状星系，有五个球状星团在暗物质密集的背景下绕轨道运行。观测分析表明，球状星团最初的质量要大得多，它们的大部分恒星都消失在了天炉座的磁场中。我们重新研究了天炉座的尖核问题，以澄清关于暗物质晕密度分布的模拟和观测之间的紧张关系。N体模拟预测了中心陡峭的幂律密度分布，而球状星团的观测似乎更倾向于中心的暗物质晕密度是恒定的。这是我们第一次用完全活跃的系统运行纯N体模拟，即由粒子（包括恒星和暗物质）组成的自引力系统。只有这种数值方法才能正确地解释天炉座和球状星团之间的动力摩擦和潮汐效应。我们发现，一个弱的尖点（$r_{s}=$ 1.5千秒差距）或一个大的核心（$r_{c}=$ 848秒差距）是不兼容的，目前观察到的位置和质量的天炉座星系团。相比之下，天炉座的一个小的暗物质核心（$r_{c}=$ 282 pc）自然地再现了初始球状星团质量范围很广的星团空间和质量分布。我们推导出一个上限为$r_{c}\lesssim$ 282 pc。这个核心大小范围只有利于暖暗数据（WDM）。如果初始晕的中央尖点被气体加热形成一个小的核心，那么也有可能从冷暗物质（CDM）理论中获得一个兼容的核心尺寸范围。

英文摘要：

Fornax is the most massive of the Milky Way dwarf spheroidal galaxies and has five globular clusters orbiting in a dense background of dark matter. Observational analyses suggest that globular clusters were initially much more massive and lost most of their stars to the Fornax field. We re-investigate the Fornax cusp-core problem, to clarify tensions between simulations and observations concerning the dark matter halo density profile. N-body simulations predict a centrally steep power-law density profile, while observations of the globular clusters seem to prefer that the dark matter halo density is constant at the center. For the first time, we ran pure N-body simulations with entirely live systems, i.e. self-gravitating systems composed of particles (including stars and dark matter). Only this numerical approach accounts correctly for dynamical friction and tidal effects between Fornax and the globular clusters. We show that a weak cusp ($r_{s}=$ 1.5 kpc) or a large core ($r_{c}=$ 848 pc) are not compatible with the current observed positions and masses of Fornax clusters. In contrast, a small dark matter core ($r_{c}=$ 282 pc) for Fornax naturally reproduces the cluster spatial and mass distributions over a wide range of initial globular cluster masses. We derive an upper limit of $r_{c}\lesssim$ 282 pc. This core size range favors only warm dark datter (WDM). It is also possible to obtain a compatible core size range from cold dark matter (CDM) theories, if the initial halo's central cusp is heated by gas to form a small core.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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英文摘要：

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