Hiroshi Koyama's Research

I'm interested in the physical processes in interstellar medium (ISM) that lead to formation of molecular clouds. My research consists of theoretical studies that include linear stability analysis and nonlinear magneto/hydrodynamical calculations. A part of my work has been dedicated to developing and implementing numerical code for vector and parallel supercomputer.

ADS Listing for past 5 years

Turbulence in ISM is a remarkable properties. On of the important source of the turbulence is the hydrodynamic instabilities, in particular, thermal instability (TI) which is a character of optically thin cosmic plasma. Triggering of TI in ISM and subsequent production of small-scale structures are investigated by my numerical simulations.

Giant Molecular Clouds (GMCs) in Galactic ISM
Another relevant source of galactic scale turbulence is stellar feedback. Eve Ostriker and I have been developing the numerical models for galactic ISM and HII regions as the stellar feedback. The self-gravitating, multiphase gas disk is simulated in a local shearing periodic box. The simulations resolve formation and disruption of GMCs controlled by the turbulence.