我们研究了大麦云云首次进入银河系暗物质晕维里半径后,大麦哲伦云对银河系演化的影响。在我们的模型中,银河系和大麦哲伦星系都被建模为N体粒子,这样大麦哲伦星系对银河系的动力学影响就可以用完全自洽的方式来研究。此外,LMC的轨道参数是精心选择的,这样的LMC在银河系中的当前位置可以在我们的模拟中相当精确地再现。我们特别研究了大麦哲伦星系对岁差率、外部恒星和气体结构以及恒星形成历史的影响。我们的主要结果总结如下。LMC与星系的动力学相互作用可以引起星系的“极移”(或不规则的岁差/章动),典型的极移速率(点θ d)为~2度Gyr^{-1},对应于~ 7 μ asyr ^{-1}。LMC与银河系的相互作用导致了银河系外部翘曲结构的形成,从而证实了以往关于银河系翘曲形成的数值模拟结果。大麦哲伦星系与星系的相互作用还导致了外盘(R>20 kpc)旋臂的形成,并显著增加了外盘的垂直速度色散。银河系最后几个旋回的平均恒星形成率几乎不受大麦哲伦星云引潮力的影响。过去几个Gyr的太阳邻域(7 kpc < R < 10 kpc)恒星的年龄和金属丰度分布仅能被过去的LMC-星系相互作用轻微改变。基于这些结果,我们讨论了如何可能正在进行的银河系极移与10 μ asyr ^{-1}可以检测到未来的观测研究GAIA。
英文摘要:
We investigate how the Large Magellanic Cloud (LMC) influences the evolution of the Galaxy after the LMC enters into the virial radius of the dark matter halo of the Galaxy for the first time. Both the Galaxy and the LMC are modeled as N-body particles in our models so that the dynamical influences of the LMC on the Galaxy can be investigated in a fully self-consistent manner. Furthermore, the orbital parameters for the LMC are carefully chosen such that the present location of the LMC in the Galaxy can be rather precisely reproduced in our simulations. We particularly investigate the influences of the LMC on the precession rate, the outer stellar and gaseous structures, and the star formation history of the Galaxy. Our principals results are summarized as follows. The LMC-Galaxy dynamical interaction can cause "pole shift" (or irregular precession/nutation) of the Galaxy and the typical rate of pole shift (dot θ_{d}) is ~2 degree Gyr^{-1} corresponding to ~ 7 muas yr^{-1}. The LMC-Galaxy interaction induces the formation of the outer warp structures of the Galaxy, which thus confirms the results of previous numerical simulations on the formation of the Galactic warp. The LMC-Galaxy interaction also induces the formation of outer (R>20 kpc) spiral arms and increases the vertical velocity dispersion of the outer disk significantly. The mean star formation rate of the Galaxy for the last several Gyrs can be hardly influenced by the LMC's tidal force. The age and metallicity distribution of stars in the solar-neighborhood (7 kpc < R < 10 kpc) for the last several Gyr can be only slightly changed by the past LMC-Galaxy interaction. Based on these results, we discuss how the possible ongoing Galactic pole shift with 10 muas yr^{-1} can be detected by future observational studies by GAIA.
Modeling the recent interactions between the Magellanic Clouds and Milky Way
Montana State University(蒙大拿州立大学);Center for Computational Astrophysics, Flatiron Institute(计算天体物理中心,富尔顿研究所);University of Lancashire(兰开夏大学);Queen’s University(女王大学)
The Role of Dwarf Galaxy Interactions in Shaping the Magellanic System and Implications for Magellanic Irregulars
根据最近的高精度自行,我们提出了一对新的大麦哲伦云和小麦哲伦云(分别为LMC和SMC)与我们的银河系(MW)之间的相互作用历史的数值模型(Kallivayalil等人,2006a,b)。考虑到新的速度,结构形成的宇宙学模拟倾向于麦哲伦云(MC)目前第一次落入我们的银河系的场景(Boylan-Kolchin et al. 2011,Busha et al. 2011)。我们在这里说明,所观察到的不规则的形态和内部运动学的MC(在气体和恒星)的LMC和SMC之间的相互作用,而不是引力与MW的相互作用自然解释。这张照片进一步支持第一个坠落场景(Besla et a. 2007年)。特别是,我们证明了麦哲伦流,HI气体落后于MCs 150度的天空,可以占LMC潮汐的SMC的行动之前,该系统是由MW吸积。我们进一步证明,偏离中心,弯曲的恒星酒吧的LMC和它的单臂螺旋,可以很自然地解释最近的直接碰撞与SMC。这样的结构是麦哲伦不规则星系的关键形态特征(de Vaucouleurs & Freeman 1972),其中大多数与大质量螺旋星系无关。我们推断,矮-矮星系相互作用是麦哲伦不规则星系形态演化的重要驱动力,并且可以通过形成扩展的潮汐桥和尾巴来显着影响从矮星系中去除重子的效率。这种相互作用不仅对矮星系的演化很重要,而且对我们自己MW中重子的积累也有直接的影响,因为LMC质量系统被认为是MW型…
A comprehensive catalogue of high-mass X-ray binaries in the Large Magellanic Cloud detected during the first eROSITA all-sky survey
Max-Planck-Institut für extraterrestrische Physik(马克斯·普朗克地外物理研究所);Inter-University Centre for Astronomy and Astrophysics (IUCAA)(大学间天文学与天体物理学中心);Anton Pannekoek Institute for Astronomy, University of Amsterdam(阿姆斯特丹大学安东·潘内库克天体物理研究所);Department of Astronomy, The University of Michigan(密歇根大学天文学系);Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM(巴黎萨克雷大学、巴黎西岱大学、CEA、CNRS、AIM);Southern African Astronomical Observatory(南非天文台);Department of Astronomy, University of Cape Town(开普敦大学天文学系);Leibniz Institut für Astrophysik Potsdam(波茨坦莱布尼茨天体物理研究所)