Impact of Cosmological Satellites on Stellar Discs: Dissecting One Satellite at a Time
Monthly Notices of the Royal Astronomical Society
Oxford University Press
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Hu, S., & Sijacki, D. (2018). Impact of Cosmological Satellites on Stellar Discs: Dissecting One Satellite at a Time. Monthly Notices of the Royal Astronomical Society, 478 (2), 1576-1594. https://doi.org/10.1093/mnras/sty1183
Within the standard hierarchical structure formation scenario, Milky Way-mass dark matter haloes have hundreds of dark matter subhaloes with mass ≳ 108 M⊙. Over the lifetime of a galactic disc, a fraction of these may pass close to the central region and interact with the disc. We extract the properties of subhaloes, such as their mass and trajectories, from a realistic cosmological simulation to study their potential effect on stellar discs. We find that massive subhalo impacts can generate disc heating, rings, bars, warps, lopsidedness as wells as spiral structures in the disc. Specifically, strong counter-rotating single-armed spiral structures form each time a massive subhalo passes through the disc. Such single-armed spirals wind up relatively quickly (over 1–2 Gyr) and are generally followed by corotating two-armed spiral structures that both develop and wind up more slowly. In our simulations, self-gravity in the disc is not very strong and these spiral structures are found to be kinematic density waves. We demonstrate that there is a clear link between each spiral mode in the disc and a given subhalo that caused it, and by changing the mass of the subhalo, we can modulate the strength of the spirals. Furthermore, we find that the majority of subhaloes interact with the disc impulsively, such that the strength of spirals generated by subhaloes is proportional to the total torque they exert. We conclude that only a handful of encounters with massive subhaloes are sufficient for regenerating and sustaining spiral structures in discs over their entire lifetime.
methods: numerical, galaxies: haloes, galaxies: spiral
SH is supported by the CSC Cambridge Scholarship, jointly funded by the China Scholarship Council and the Cambridge Overseas Trust, and by the Lundgren Research Award, funded by the University of Cambridge and the Lundgren Fund. DS acknowledges support by the STFC (Science and Technology Facilities Council) and ERC (European Research Council) Starting Grant 638707 ‘Black holes and their host galaxies: co-evolution across cosmic time’. This work was performed on: DiRAC (Distributed Research utilizing Advanced Computing) Darwin Supercomputer hosted by the University of Cambridge High Performance Computing Service (http://www.hpc.cam.ac.uk/), provided by Dell Inc. using Strategic Research Infrastructure Funding from the Higher Education Funding Council for England and funding from the Science and Technology Facilities Council; DiRAC Complexity system, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility (www.dirac.ac.uk). This equipment is funded by BIS National E-Infrastructure capital grant ST/K000373/1 and STFC DiRAC Operations grant ST/K0003259/1; COSMA Data Centric system at Durham University, operated by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility. This equipment was funded by a BIS National E-infrastructure capital grant ST/K00042X/1, STFC capital grant ST/K00087X/1, DiRAC Operations grant ST/K003267/1, and Durham University. DiRAC is part of the National E-Infrastructure.
ECH2020 EUROPEAN RESEARCH COUNCIL (ERC) (638707)
SCIENCE & TECHNOLOGY FACILITIES COUNCIL (ST/N000927/1)
External DOI: https://doi.org/10.1093/mnras/sty1183
This record's URL: https://www.repository.cam.ac.uk/handle/1810/282866