3 juillet - 6 juillet 2018

Abstract

S12 Synergie des grands surveys pour comprendre les étoiles : piliers de l’archéologie galactique

Chemodynamical modeling of thick disk formation and star formation quenching in Milky Way-type galaxies

Khoperskov Sergey

Galaxy surveys have demonstrated a rapid and sustained decrease in the star-formation rate. Recent observational results imply that the Milky Way “quenched” about 9–10 Gyr ago, at the transition between the cessation of the growth of the kinematically hot, old, metal-poor thick disk and the kinematically colder, younger, and more metal-rich thin disk. Although perhaps coincidental, the quenching episode could also be related to the formation of the bar. To explore the relationship between the thick disk formation and the quenching episode in gas-rich galaxies quantitatively, we simulate the formation and evolution of isolated barred galaxies with various parameters. Our simulations include self-consistent chemical evolution of stellar population, star formation, stellar feedback, and the multi-phase interstellar medium. We find that the action of stellar bar efficiently quenches star formation, reducing the star-formation rate by a factor of ~10 in less than 1 Gyr. Simulations suggest that the action of the stellar bar increases the gas random motions within the co-rotation radius of the bar. Indeed, we detect an increase in the gas velocity dispersion up to 20 − 35 km/s at the end of the bar formation phase. Indeed the transfer of energy from the large-scale shear induced by the bar to increasing turbulent energy stabilize the gaseous disk against wide-spread star formation and quench the galaxy. We also discuss some chemical manifestations of the quenching in disks of the Milky Way-type simulated galaxies.