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.

13 pages, 14 figures, accepted for publication in PASJ

References in corpus (9)

• The Radial Velocity Experiment (RAVE): first data release
• 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
• Kinematic modelling of the Milky Way using the RAVE and GCS stellar surveys
• Age velocity dispersion relations and heating histories in disc galaxies
• Re-visiting the relations: Galactic thin disc age-velocity dispersion relation
• 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
• Eventful Evolution of Giant Molecular Clouds in Dynamically Evolving Spiral Arms

Cited by in corpus (7)

• Disk settling and dynamical heating: histories of Milky Way-mass stellar disks across cosmic time in the FIRE simulations
• Dynamical effects of the scale invariance of the empty space: The fall of dark matter ?
• 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
• Efficient radial migration by giant molecular clouds in the first several hundred Myr after the stellar birth
• Large-Scale Stellar Age-Velocity Spiral Pattern in NGC 4030
• Asteroseismology of red giants & galactic archaeology