Dynamical Effects of CDM Subhalos on a Galactic Disk

Abstract

We investigate the dynamical interaction between a galactic disk and surrounding numerous dark subhalos as expected for a galaxy-sized halo in the cold dark matter (CDM) models. Our particular interest is to what extent accretion events of subhalos into a disk are allowed in light of the observed thinness of a disk. Several models of subhalos are considered in terms of their internal density distribution, mass function, and spatial and velocity distributions. Based on a series of N-body simulations, we find that the disk thickening quantified by the change of its scale height, Delta z_d, depends strongly on the individual mass of an interacting subhalo M_{sub}. This is described by the relation, Delta z_d / R_d = 8 Sum_{j=1}^N (M_{sub,j}/M_d)**2, where R_d is a disk scale length, M_d is a disk mass, and N is the total number of accretion events of subhalos inside a disk region (< 3R_d). Using this relation, we find that an observed thin disk has not ever interacted with subhalos with the total mass of more than 15% disk mass. Also, a less massive disk with smaller circular velocity V_c is more affected by subhalos than a disk with larger V_c, in agreement with the observation. Further implications of our results for the origin of a thick disk component are also discussed.

12 pages, 9 figures, accepted by PASJ

Cited by in corpus (38)

• Extragalactic Science, Cosmology and Galactic Archaeology with the Subaru Prime Focus Spectrograph (PFS)
• Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
• Cold Dark Matter Substructure and Galactic Disks I: Morphological Signatures of Hierarchical Satellite Accretion
• Unified Rotation Curve of the Galaxy -- Decomposition into de Vaucouleurs Bulge, Disk, Dark Halo, and the 9-kpc Rotation Dip --
• Thin, thick and dark discs in LCDM
• Merger Histories of Galaxy Halos and Implications for Disk Survival
• Thin disc, Thick Disc and Halo in a Simulated Galaxy
• From dawn till disk: Milky Way's turbulent youth revealed by the APOGEE+Gaia data
• Chemical abundances of the Milky Way thick disk and stellar halo II.: sodium, iron-peak and neutron-capture elements
• Cold Dark Matter Substructure and Galactic Disks II: Dynamical Effects of Hierarchical Satellite Accretion
• Thick disks of edge-on galaxies seen through the Spitzer Survey of Stellar Structure in Galaxies (S4G): Lair of missing baryons?
• Antitruncated Stellar Disks via Minor Mergers
• Observational Properties of the Metal-Poor Thick Disk of the Milky Way Galaxy and Insights into Its Origins
• A Connection Between Bulge Properties and the Bimodality of Galaxies
• The Radical Consequences of Realistic Satellite Orbits for the Heating and Implied Merger Histories of Galactic Disks
• The Destruction of Thin Stellar Disks Via Cosmologically Common Satellite Accretion Events
• The Kinematics of Thick Disks in Nine External Galaxies
• Lick Indices in the Thin and Thick Disks of Edge-On Disk Galaxies
• Planetary Nebulae in Face-On Spiral Galaxies. III. Planetary Nebula Kinematics and Disk Mass
• The Once and Future Andromeda Stream
• Evidence of a thick disk rotation-metallicity correlation
• The kinematic identification of a thick stellar disc in M31
• The thick disk in the galaxy NGC 4244 from S4G imaging
• The DiskMass Survey. IV. The Dark-Matter-Dominated Galaxy UGC 463
• Pseudo Rotation Curve connecting the Galaxy, Dark Halo, and Local Group
• Thick-disk evolution induced by the growth of an embedded thin disk
• Kinematic Evidence for Halo Substructure in Spiral Galaxies
• The prolate dark matter halo of the Andromeda galaxy
• The Young Outer Disk of M83
• Simulating Sinking Satellites with SUPERBOX-10
• Effect of small scale density perturbations on the formation of dark matter halo profiles
• The Radial Distribution of Mono-Metallicity Populations in the Galactic Disk as Evidence for Two-Phase Disk Formation
• Kinematical & Chemical Characteristics of the Thin and Thick Disks
• The star-formation history of the Milky Way Galaxy
• Semi-Analytic Modeling of Dark Matter Subhalo Encounters with Thin Stellar Streams: Statistical Predictions for GD-1-like Streams in CDM
• On the Size Evolution of a Galactic Disk in Hierarchical Merging of Cold Dark Matter Halos
• Relationship between rotation curves and matter distribution in spiral galaxy discs
• CROCODILE-DWARF: Assembly and Kinematics of Field Dwarf Galaxies with GADGET4-OSAKA