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Stellar spiral structures in triaxial dark matter haloes

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Hu, S 


We employ very high resolution simulations of isolated Milky Way-like galaxies to study the effect of triaxial dark matter haloes on exponential stellar discs. Non-adiabatic halo shape changes can trigger two-armed grand-design spiral structures which extend all the way to the edge of the disc. Their pattern speed coincides with the inner Lindblad resonance indicating that they are kinematic density waves which can persist up to several Gyr. In dynamically cold discs, grand-design spirals are swing amplified and after a few Gyr can lead to the formation of (multi-armed) transient recurrent spirals. Stellar discs misaligned to the principal planes of the host triaxial halo develop characteristic integral shaped warps, but otherwise exhibit very similar spiral structures as aligned discs. For the grand-design spirals in our simulations, their strength dependence with radius is determined by the torque on the disc, suggesting that by studying grand-design spirals without bars it may be possible to set constraints on the tidal field and host dark matter halo shape.



methods: numerical, galaxies: haloes, galaxies: spiral

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Monthly Notices of the Royal Astronomical Society

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Oxford University Press
European Research Council (638707)
Science and Technology Facilities Council (ST/L000725/1)
STFC (ST/M007073/1)
Science and Technology Facilities Council (ST/N000927/1)
Science and Technology Facilities Council (ST/P002315/1)
SH is supported by the CSC Cambridge Scholarship, jointly funded by the China Scholarship Council and by the Cambridge Overseas Trust. DS acknowledges support by the STFC and ERC Starting Grant 638707 ‘Black holes and their host galaxies: co-evolution across cosmic time’. This work was performed on DiRAC Darwin Supercomputer hosted by the University of Cambridge High Performance Computing Service (, 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 ( 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.