ISM/Molecular Cloud/Star Formation Simulations Alexei Kritsuk UCSD - - PowerPoint PPT Presentation

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ISM/Molecular Cloud/Star Formation Simulations Alexei Kritsuk UCSD - - PowerPoint PPT Presentation

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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,

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ISM/Molecular Cloud/Star Formation Simulations

Alexei Kritsuk

UCSD

The Future of AstroComputing SDSC, December 17, 2010

Collaborators: David Collins (UCSD) Paolo Padoan (ICREA/Barcelona) Mike Norman (SDSC) Sergey Ustyugov (Keldysh/Moscow) Rick Wagner (SDSC)

Friday, December 17, 2010

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Dust structures within 150 parsecs of the Sun

Friday, December 17, 2010

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Molecular gas, B-fields & YSO in Taurus

  • Filamentary hierarchical structure
  • f MCs
  • Magnetic field lines are

preferentially ⊥ to the filaments

  • Stars form in dense cold

molecular cores deep within the filaments

Friday, December 17, 2010

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Initial conditions for star formation

Friday, December 17, 2010

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Initial conditions for star formation

  • Turbulence

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Initial conditions for star formation

  • Turbulence

Friday, December 17, 2010

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Initial conditions for star formation

  • Turbulence
  • Gravity

Friday, December 17, 2010

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SLIDE 8

Initial conditions for star formation

  • Turbulence
  • Gravity

Friday, December 17, 2010

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Initial conditions for star formation

  • Turbulence
  • Gravity
  • Magnetic fields

Friday, December 17, 2010

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SLIDE 10

Initial conditions for star formation

  • Turbulence
  • Gravity
  • Magnetic fields

Friday, December 17, 2010

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Initial conditions for star formation

  • Turbulence
  • Gravity
  • Magnetic fields
  • Thermodynamics

Friday, December 17, 2010

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Initial conditions for star formation

  • Turbulence
  • Gravity
  • Magnetic fields
  • Thermodynamics
  • Radiative feedback
  • Outflows

Friday, December 17, 2010

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  • I. Turbulence

Friday, December 17, 2010

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Universal linewidth-size relation

Friday, December 17, 2010

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ENZO simulation 2008

Friday, December 17, 2010

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Supersonic turbulence: Scaling - I

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Supersonic turbulence: Scaling - II

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Supersonic turbulence: Scaling - III

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Supersonic turbulence: Scaling - IV

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Supersonic turbulence: Energy cascade

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Supersonic turbulence: Intermittency

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  • II. Gravity

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Lognormal density PDF

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Power-law tails in the density PDF

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Power-law tails in the density PDF

Star-forming MCs Non-star-forming MCs

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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

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Power-law tails in the density PDF

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Power-law tails in the density PDF

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Power-law tails in the density PDF

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  • III. B-fields

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Self-organization in MHD turbulence

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Self-organization in MHD turbulence

  • ISM is a turbulent driven dissipative system

Friday, December 17, 2010

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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

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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

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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

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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

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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

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Global energetics

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Time-evolution of cloudy structures

Projected gas density for Model A (200 pc box)

t = 2 Myr t = 3 Myr t = 4 Myr Two-phase medium Turbulence forcing is ON Developed turbulence

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Time-evolution of cloudy structures

Projected gas density for Model A

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Time-evolution of cloudy structures

Projected gas density for Model A

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Structures in the multiphase ISM

Density Magnetic energy

Dense material is assembled in hierarchical filamentary structures Large molecular complexes contain comparable amounts of HI

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“Thermodynamics”

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Dynamic alignment

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Magnetic vs. dynamic pressure

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B-n diagram

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  • IV. Numerics

Friday, December 17, 2010

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Supersonic MHD turbulence decay test

Kinetic energy Magnetic energy Re Rem

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Supersonic MHD turbulence decay test

Velocity B-field Dilatational-to-solenoidal velocity ratio

Friday, December 17, 2010

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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