MW dSphs作为无DM TDG的后代的再生性能
Reproducing properties of MW dSphs as descendants of DM-free TDGs
摘要：
银河系（MW）矮椭球（dSph）卫星是已知最暗物质（DM）占主导地位的星系，估计暗物质到重子物质甚至达到100多个。它来自于这样的假设，即矮星是由它们观测到的速度色散动态支持的。然而，它们在MW周围的空间分布并不是随机的，这可能会挑战它们的起源，以前认为它们是由MW势吸积的原始星系的残余物。在这里，我们表明，或者，dSphs可能是潮汐矮星系（TDGs），这将与银河系热气晕和磁盘相互作用的残余物。TDG富含天然气，形成于M31位置古代合并事件期间产生的潮汐尾，并向MW排出。我们的模拟结果表明，低质量TDG是脆弱的MW盘和晕热气体的相互作用。在相互作用过程中，它们的恒星含量逐渐脱离平衡并强烈膨胀，导致低表面亮度特征并模仿高动态M/L比。我们的模型可以重现的属性，包括运动学，经典MW矮星的质量范围内的麦哲伦云天龙座。在M31位置的一个古老的富含气体的合并可能会挑战目前假设的矮星系中高含量的暗物质。我们提出了一个简单的观测测试与即将到来的盖亚任务，按照他们预期的恒星膨胀，这不应该在目前的理论框架内观察到。
英文摘要：
The Milky Way (MW) dwarf spheroidal (dSph) satellites are known to be the most dark-matter (DM) dominated galaxies with estimates of dark to baryonic matter reaching even above one hundred. It comes from the assumption that dwarfs are dynamically supported by their observed velocity dispersions. However their spatial distributions around the MW is not at random and this could challenge their origin, previously assumed to be residues of primordial galaxies accreted by the MW potential. Here we show that alternatively, dSphs could be the residue of tidal dwarf galaxies (TDGs), which would have interacted with the Galactic hot gaseous halo and disk. TDGs are gas-rich and have been formed in a tidal tail produced during an ancient merger event at the M31 location, and expelled towards the MW. Our simulations show that low-mass TDGs are fragile to an interaction with the MW disk and halo hot gas. During the interaction, their stellar content is progressively driven out of equilibrium and strongly expands, leading to low surface brightness feature and mimicking high dynamical M/L ratios. Our modeling can reproduce the properties, including the kinematics, of classical MW dwarfs within the mass range of the Magellanic Clouds to Draco. An ancient gas-rich merger at the M31 location could then challenge the currently assumed high content of dark matter in dwarf galaxies. We propose a simple observational test with the coming GAIA mission, to follow their expected stellar expansion, which should not be observed within the current theoretical framework.
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