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Dynamics of Multi-Phase Interstellar Medium

Dynamics of Multi-Phase Interstellar Medium. Thanks to Hiroshi Koyama (Univ. Maryland) Tsuyoshi Inoue (Kyoto Univ.) Patrick Hennebelle (Paris Obs. & ENS) Masahiro Nagashima (Nagasaki Univ.) Keywords: radiative cooling/heating, thermal instability, MHD, ambipolar diffusion, etc.

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Dynamics of Multi-Phase Interstellar Medium

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  1. Dynamics of Multi-Phase Interstellar Medium Thanks to Hiroshi Koyama (Univ. Maryland) Tsuyoshi Inoue (Kyoto Univ.) Patrick Hennebelle (Paris Obs. & ENS) Masahiro Nagashima (Nagasaki Univ.) Keywords: radiative cooling/heating, thermal instability, MHD, ambipolar diffusion, etc. Shu-ichiro Inutsuka (Nagoya Univ)

  2. PolarizationMapofSynchrotronRad Depolarizedregionlookslike Canal! Nogoodtheoryyet!

  3. Ferrière 2001, Rev.Mod.Phys. 73, 1031 nvs Height from Galactic Midplane ionizedgas HIgas averagenumberdensityn cm-3 H2gas

  4. PCR > Pmag > PgasParkerInstability? Pgas Vertical(Quasi-)HydrostaticEquilibrium? Ferrière 2001, Rev.Mod.Phys. 73, 1031

  5. VariousComponents(Radial) NGC6946 equipartition assumed MRIdoesnotexplainthis!

  6. M51 Synchrotron Polarization (Fletcher & Beck2005)

  7. Dynamical Timescale of ISM • Dynamical Three Phase Medium • McKee & Ostriker 1977 • SN Explosion Rate in Galaxy… 1/(100yr) • Expansion Time…1Myr • Expansion Radius… 100pc • （10-2 yr-1 ）（106 yr ）（100pc）3 = 1010 pc3 VGal.Disk • Dynamical Timescale of ISM 1Myr • « Timescale of Galactic Density Wave 100Myr (10kpc)2 100pc

  8. CGPS data in W5 HII region 21cm continuum (HII gas) Tb=5K (bright) → 12.5K (dark) Image : 60mm dust emission Contour : 12CO(1-0) @ vLSR=-39.8 km/s • Ionized gas is surrounded with the dust shell. • Distribution of CO molecules show poor correlation with • the dust shell.

  9. CGPS data in W5 HII region HI 21cm emission @ vLSR=-39.8 km/s : Tb=45K (bright) → 110K (dark) contour : 60μm dust emission • Shell-like HISelf-Absorption feature is found around W5. • HISA feature overlaps with the dust shell. • Hosokawa & SI 2007, ApJ 664, 363 • SeealsorecentPlanckpaper(arXiv1101.2029)on“DarkGas”

  10. Radiative Equilibrium Solid: NH=1019cm-2, Dashed: 1020cm-2 WNM (Warm Medium) CNM(Cold Medium)

  11. Radiative Cooling & Heating Solid: Cooling, Dashed: Heating grains Koyama & Inutsuka (2000) ApJ 532, 980 , based on Wolfire et al. 1995

  12. 2D Evolution from Unstable Equilibrium Periodic Box Evolution without Shock Driving With Cooling/Heating and Thermal Conduction Without Physical Viscosity  Pr = 0

  13. Density-Pressure Diagram Density-Temperature Diagram through unstable region 1D Shock Propagation intoWNM unstable Koyama & SI 2000, ApJ 532, 980 See also Hennebelle & Pérault 1999

  14. 104*104 pixels Audit & Hennebelle 2007 3D simulations 12003 20 pc Heitsch et al. 40962 2D Hennebelle & Audit 07 10,0002

  15. Property of "Turbulence" dv < CS,WNM Kolmogorov-like Spectrum Hennebelle & Audit 2007

  16. Property of "Turbulence" Hennebelle & Audit 2007 dv < CS,WNM Kolmogorov-like Spectrum Armstrong, Rickett, & Spangler 1995

  17. Smaller CNM cloud evaporates: R~0.01pc clouds evaporate in ~Myr Nagashima, Koyama, Inutsuka & 2005, MNRAS 361, L25 Nagashima, Inutsuka, & Koyama 2006, ApJL 652, L41 evaporation condensation WNM CNM Rc Analytic Formula Evaporation of Spherical CNM in WNM Evaporation Timescale Size of CNM cloud

  18. If the ambient pressure is larger, the critical size of the stable cloud is smaller. "Tiny Scale Atomic Structure"? Braun & Kanekar 2005 Nagashima, Inutsuka, & Koyama 2006, ApJL 652, L41 WNM CNM Rc Evaporation of Spherical CNM in WNM Critical Radius Ambient Pressure

  19. Summary • Shock waves in ISM create Turbulent CNM embedded in WNM. • In TurbulentMulti-Phase ISM • Thermal Instability, Magnetic Field, Ambipolar Diffusion, etc. What next Turbulent Diffusion of Magnetic Field Particle Acceleration Overall Modeling of Gaseous Galactic Halo GoodInformationfromCMBobservations

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