Dark matter spiral arms in Milky Way-like halos

Abstract

The coupling between the dark matter (DM) halo and the stellar disc is a key factor in galactic evolution. While the interaction between structures like the Galactic bar and DM halos has been explored (e.g. slowing down of the bar due to dynamical friction), the effect of spiral arms on the DM halo distribution has received limited attention. We analyze a suite of simulations featuring strong stellar spiral arms, ranging in complexity from test-particle models to fully cosmological hydrodynamical simulations. Using Fourier transforms, we characterize the phase and amplitude of the stellar spirals at different times and radii. We then apply the same methodology to DM particles near the stellar disc and compare trends in Fourier coefficients and phases between the two components. We detect a clear spiral arm signal in the DM distribution, correlated with the stellar spirals, confirming the reaction of the halo. The strength of the DM spirals consistently measures around 10\% of that of the stellar spiral arms. In the $N$-body simulation, the DM spiral persistently trails the stellar spiral arm by approximately $10^{\circ }$. A strong spiral signal of a few km\,s${}^{-1}$ appears in the radial, azimuthal, and vertical velocities of halo particles, distinct from the stellar kinematic signature. In a test-particle simulation with an analytical spiral potential (omitting self-gravity), we reproduce a similar density and kinematic response, showing that the test-particle halo responds in the same way as the $N$-body halo. Finally, we also find the rest of the simulations, indicating that the dynamical signatures of the forced response in the DM halo are independent of the dynamical origin of the stellar spiral arms. We reveal the ubiquitous presence of DM spiral arms in Milky Way-like galaxies, driven by a forced response to the stellar spiral potential. (ABR)

14 pages, 9 figures. Accepted for publication in Astronomy & Astrophysics

References in corpus (18)

• The mass distribution and gravitational potential of the Milky Way
• Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
• Dawes Review 4: Spiral Structures in Disc Galaxies
• On the origin of rR_1 ring structures in barred galaxies
• Bending and Breathing Modes of the Galactic Disk
• Radial and vertical flows induced by galactic spiral arms: likely contributors to our "wobbly Galaxy''
• Detection of the Milky Way reflex motion due to the Large Magellanic Cloud infall
• Action-based distribution functions for spheroidal galaxy components
• On the galaxy spiral arms' nature as revealed by rotation frequencies
• The Vertical Structure and Kinematics of Grand Design Spirals
• Quantifying the Stellar Halo's Response to the LMC's Infall with Spherical Harmonics
• Dark matter halo shapes in the Auriga simulations
• Bringing the Galaxy's dark halo to life
• Energy wrinkles and phase-space folds of the last major merger
• Dynamical Friction, Buoyancy and Core-Stalling -- I. A Non-perturbative Orbit-based Analysis
• The relative efficiencies of bars and clumps in driving disc stars to retrograde motion
• Spiral instabilities: little interaction with a live halo
• Estimating the Oblateness Of Dark Matter Halos Using Neutral Hydrogen Velocity Dispersion

Cited by in corpus (1)

• The dark matter wake of a galactic bar revealed by multichannel Singular Spectral Analysis