论文标题
潮汐能解释福纳克斯的低暗物质密度吗？
Can tides explain the low dark matter density in Fornax?
论文作者
论文摘要
Fornax Dwarf星系中的低暗物质密度通常被解释为由于存在恒定密度“核心”，但也可以通过银河系潮汐的影响来解释。后一种解释被散布了，因为它显然与Fornax的轨道参数和星形形成历史不一致。我们在使徒宇宙学水动力学模拟的帮助下重新审视了这些论点。我们表明，模拟具有与FORNAX相似特性的矮人能够在输入后形成恒星，因此恒星形成不一定是Inclall Time的良好示踪剂。我们还检查了对Fornax围口的限制，并指出目前尚未将小的小围式（<50 kpc）排除在数据中，从而使Fornax对其当前轨道受到潮湿的影响。此外，我们发现，由于与更大的星系相互作用，可以在输入之前剥离一些具有大轨道围腹的矮人。潮汐效应导致暗物质密度的降低，而轮廓保持尖锐。 Navarro-frenk-White配置文件与最内向区域的3 $σ$内的运动学数据一致，而具有浅尖或核心的轮廓可更好地拟合。我们预测，如果最少在某种程度上，由于银河潮汐的作用，在某种程度上发生了暗物质密度，那么在调查区域中，潮汐尾巴的表面亮度极限为$ \ sim35-36 $ \ sim35-36 $ \ sim35-36 $ \ sim35-36 $ \ gtrsim $ \ gtrsim $ \ gtrsim $ 100 get $^$^2 $^2 $^2 $^2 $^2 $^2 $^2 $^2 $^2 $^2 $^2 $^2 $。
The low dark matter density in the Fornax dwarf galaxy is often interpreted as being due to the presence of a constant density `core', but it could also be explained by the effects of Galactic tides. The latter interpretation has been disfavoured because it is apparently inconsistent with the orbital parameters and star formation history of Fornax. We revisit these arguments with the help of the APOSTLE cosmological hydrodynamics simulations. We show that simulated dwarfs with similar properties to Fornax are able to form stars after infall, so that star formation is not necessarily a good tracer of infall time. We also examine the constraints on the pericentre of Fornax and point out that small pericentres (<50 kpc) are not currently ruled out by the data, allowing for Fornax to be tidally influenced on its current orbit. Furthermore, we find that some dwarfs with large orbital pericentres can be stripped prior to infall due to interactions with more massive galaxies. Tidal effects lead to a reduction in the dark matter density, while the profile remains cuspy. Navarro-Frenk-White profiles are consistent with the kinematic data within 3$σ$ in the innermost regions, while profiles with shallow cusps or cores provide a better fit. We predict that if the reduction of the dark matter density in Fornax occurs, at least in part, because of the action of Galactic tides, then tidal tails should be visible with a surface brightness limit of $\sim35-36$ mag arcsec$^{-2}$ over a survey area of $\gtrsim$100 deg$^2$.
