Imprints of Zero-Age Velocity Dispersions and Dynamical Heating on the Age-Velocity dispersion Relation

Abstract

Observations of stars in the the solar vicinity show a clear tendency for old stars to have larger velocity dispersions. This relation is called the age-velocity dispersion relation (AVR) and it is believed to provide insight into the heating history of the Milky Way galaxy. Here, in order to investigate the origin of the AVR, we performed smoothed particle hydrodynamic simulations of the self-gravitating multiphase gas disks in the static disk-halo potentials. Star formation from cold and dense gas is taken into account, and we analyze the evolution of these star particles. We find that exponents of simulated AVR and the ratio of the radial to vertical velocity dispersion are close to the observed values. We also find that the simulated AVR is not a simple consequence of dynamical heating. The evolution tracks of stars with different epochs evolve gradually in the age-velocity dispersion plane as a result of: (1) the decrease in velocity dispersion in star forming regions, and (2) the decrease in the number of cold/dense/gas as scattering sources. These results suggest that the AVR involves not only the heating history of a stellar disk, but also the historical evolution of the ISM in a galaxy.

arXiv comment13 pages, 14 figures, accepted for publication in PASJ

References in corpus (45)

• A Universal Density Profile from Hierarchical Clustering
• E pur si muove: Galiliean-invariant cosmological hydrodynamical simulations on a moving mesh
• Cosmological Hydrodynamics with Adaptive Mesh Refinement: a new high resolution code called RAMSES
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• SEGUE: A Spectroscopic Survey of 240,000 stars with g=14-20
• The New Galaxy: Signatures of its Formation
• The SINS survey: SINFONI Integral Field Spectroscopy of z ~ 2 Star-forming Galaxies
• GAIA: Composition, Formation and Evolution of the Galaxy
• Local stellar kinematics from Hipparcos data
• Radial Mixing in Galactic Discs
• The Radial Velocity Experiment (RAVE): first data release
• The Geneva-Copenhagen Survey of the Solar neighbourhood III. Improved distances, ages, and kinematics
• Quantifying the Fragility of Galactic Disks in Minor Mergers
• The Geneva-Copenhagen Survey of the Solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk
• Molecular Hydrogen and Global Star Formation Relations in Galaxies
• Kinematics and history of the solar neighbourhood revisited
• Inside Out and Upside Down: Tracing the Assembly of a Simulated Disk Galaxy Using Mono-Age Stellar Populations
• Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: II. The Molecular Gas Disk
• Thin disc, Thick Disc and Halo in a Simulated Galaxy
• A Necessary Condition for Individual Time-Steps in SPH Simulations
• The dynamics of stars around spiral arms
• The stellar velocity distribution in the solar neighbourhood
• Radial Migration in Disk Galaxies I: Transient Spiral Structure and Dynamics
• Vertical disc heating in Milky Way-sized galaxies in a cosmological context
• Dynamics of Non-Steady Spiral Arms in Disk Galaxies
• Toward first-principle simulations of galaxy formation: I. How should we choose star formation criteria in high-resolution simulations of disk galaxies?
• Molecular Gas Disk Structures around AGNs
• Kinematic modelling of the Milky Way using the RAVE and GCS stellar surveys
• Age velocity dispersion relations and heating histories in disc galaxies
• Dynamics of stars around spiral arms in an N-body/SPH simulated barred-spiral galaxy
• Re-visiting the relations: Galactic thin disc age-velocity dispersion relation
• Simulations of the heating of the Galactic stellar disc
• Dissecting simulated disc galaxies II: the age-velocity relation
• The impact of radio feedback from active galactic nuclei in cosmological simulations: Formation of disk galaxies
• Disc Heating: Comparing the Milky Way with Cosmological Simulations
• Resolution requirements for simulating gravitational fragmentation using SPH
• The quiescent phase of galactic disc growth
• Towards a fully consistent Milky Way disc model: Part 1 The local model based on kinematic and photometric data
• Phantom-GRAPE: numerical software library to accelerate collisionless $N$-body simulation with SIMD instruction set on x86 architecture
• Tidal disruption of dark matter halos around proto-globular clusters
• FAST: A Fully Asynchronous Split Time-Integrator for Self-Gravitating Fluid
• Eventful Evolution of Giant Molecular Clouds in Dynamically Evolving Spiral Arms
• Santa Barbara Cluster Comparison Test with DISPH
• Global Spiral Arms Formation by Non-linear Interaction of Wakelets

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• The Fornax3D project: Assembly histories of lenticular galaxies from a combined dynamical and population orbital analysis
• The Scale-Invariant Vacuum (SIV) Theory: A Possible Origin of Dark Matter and Dark Energy
• Metallicity dependence of the Hercules stream in Gaia/RAVE data -- explanation by non-closed orbits
• Efficient radial migration by giant molecular clouds in the first several hundred Myr after the stellar birth
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