ISM/Molecular Cloud/Star Formation Simulations Alexei Kritsuk UCSD Collaborators: David Collins (UCSD) Paolo Padoan (ICREA/Barcelona) Mike Norman (SDSC) Sergey Ustyugov (Keldysh/Moscow) Rick Wagner (SDSC) The Future of AstroComputing SDSC, December 17, 2010 Friday, December 17, 2010
Dust structures within 150 parsecs of the Sun Friday, December 17, 2010
Molecular gas, B-fields & YSO in Taurus • Filamentary hierarchical structure of MCs • Magnetic field lines are preferentially ⊥ to the filaments • Stars form in dense cold molecular cores deep within the filaments Friday, December 17, 2010
Initial conditions for star formation Friday, December 17, 2010
Initial conditions for star formation • Turbulence Friday, December 17, 2010
Initial conditions for star formation • Turbulence Friday, December 17, 2010
Initial conditions for star formation • Turbulence • Gravity Friday, December 17, 2010
Initial conditions for star formation • Turbulence • Gravity Friday, December 17, 2010
Initial conditions for star formation • Turbulence • Gravity • Magnetic fields Friday, December 17, 2010
Initial conditions for star formation • Turbulence • Gravity • Magnetic fields Friday, December 17, 2010
Initial conditions for star formation • Turbulence • Gravity • Magnetic fields • Thermodynamics Friday, December 17, 2010
Initial conditions for star formation • Turbulence • Gravity • Magnetic fields • Thermodynamics • Radiative feedback • Outflows Friday, December 17, 2010
I. Turbulence Friday, December 17, 2010
Universal linewidth-size relation Friday, December 17, 2010
ENZO simulation 2008 Friday, December 17, 2010
Supersonic turbulence: Scaling - I Friday, December 17, 2010
Supersonic turbulence: Scaling - II Friday, December 17, 2010
Supersonic turbulence: Scaling - III Friday, December 17, 2010
Supersonic turbulence: Scaling - IV Friday, December 17, 2010
Supersonic turbulence: Energy cascade Friday, December 17, 2010
Supersonic turbulence: Intermittency Friday, December 17, 2010
II. Gravity Friday, December 17, 2010
Lognormal density PDF Friday, December 17, 2010
Power-law tails in the density PDF Friday, December 17, 2010
Power-law tails in the density PDF Star-forming MCs Non-star-forming MCs Friday, December 17, 2010
Power-law tails in the density PDF Klessen 2000 (SPH) Slyz + 2005 (ENZO) Vazquez-Semadeni + 2008 (TVD) Dib & Burkert 2005 (ZEUS-MP) Federrath + 2008 (ENZO) Collins + 2010 (AMR-MHD) Friday, December 17, 2010
Power-law tails in the density PDF Friday, December 17, 2010
Power-law tails in the density PDF Friday, December 17, 2010
Power-law tails in the density PDF Friday, December 17, 2010
III. B-fields Friday, December 17, 2010
Self-organization in MHD turbulence Friday, December 17, 2010
Self-organization in MHD turbulence • ISM is a turbulent driven dissipative system Friday, December 17, 2010
Self-organization in MHD turbulence • ISM is a turbulent driven dissipative system • Kinetic energy is injected at large scales • Turbulent cascade of energy Friday, December 17, 2010
Self-organization in MHD turbulence • ISM is a turbulent driven dissipative system • Kinetic energy is injected at large scales • Turbulent cascade of energy • Mean magnetic field, turbulent component Friday, December 17, 2010
Self-organization in MHD turbulence • ISM is a turbulent driven dissipative system • Kinetic energy is injected at large scales • Turbulent cascade of energy • Mean magnetic field, turbulent component • Thermal energy input, radiative cooling Friday, December 17, 2010
Self-organization in MHD turbulence • ISM is a turbulent driven dissipative system • Kinetic energy is injected at large scales • Turbulent cascade of energy • Mean magnetic field, turbulent component • Thermal energy input, radiative cooling • Usual MHD constraints (conservation laws) • Relaxation through nonlinear interactions Friday, December 17, 2010
Self-organization in MHD turbulence • ISM is a turbulent driven dissipative system • Kinetic energy is injected at large scales • Turbulent cascade of energy • Mean magnetic field, turbulent component • Thermal energy input, radiative cooling • Usual MHD constraints (conservation laws) • Relaxation through nonlinear interactions • MCs form as dissipative structures (active regions of intermittent turbulent cascade that drain the kinetic energy supplied by forcing) Friday, December 17, 2010
Global energetics Friday, December 17, 2010
Time-evolution of cloudy structures Projected gas density for Model A (200 pc box) Two-phase medium Turbulence forcing is ON Developed turbulence t = 2 Myr t = 3 Myr t = 4 Myr Friday, December 17, 2010
Time-evolution of cloudy structures Projected gas density for Model A Friday, December 17, 2010
Time-evolution of cloudy structures Projected gas density for Model A Friday, December 17, 2010
Structures in the multiphase ISM Density Magnetic energy Dense material is assembled in hierarchical filamentary structures Large molecular complexes contain comparable amounts of HI Friday, December 17, 2010
“Thermodynamics” Friday, December 17, 2010
Dynamic alignment Friday, December 17, 2010
Magnetic vs. dynamic pressure Friday, December 17, 2010
B-n diagram Friday, December 17, 2010
IV. Numerics Friday, December 17, 2010
Supersonic MHD turbulence decay test Kinetic energy Magnetic energy Re Re m Friday, December 17, 2010
Supersonic MHD turbulence decay test Velocity B-field Dilatational-to-solenoidal velocity ratio Friday, December 17, 2010
Summary • We now understand ISM turbulence “better” • More work ahead on MHD, dynamo, etc. • Large MHD simulations on uniform grids • Better numerical methods (accuracy and stability are crucial) • Deep AMR-MHD star formation simulations • More complex physics (non-ideal effects, chemistry, RT) Friday, December 17, 2010
Recommend
More recommend
