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Non-Equilibrium Ionization

Non-Equilibrium Ionization. in Metal Ion Absorbers and. in Post-Shock Cooling Layers. Gnat & Sternberg 2007, ApJS, 168, 213. Gnat & Sternberg 2008, ApJ submitted. Orly Gnat (Caltech) with Amiel Sternberg (Tel-Aviv University). Non–Equilibrium Radiative Cooling.

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Non-Equilibrium Ionization

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  1. Non-Equilibrium Ionization in Metal Ion Absorbers and in Post-Shock Cooling Layers Gnat & Sternberg 2007, ApJS, 168, 213 Gnat & Sternberg 2008, ApJ submitted Orly Gnat (Caltech) with Amiel Sternberg (Tel-Aviv University)

  2. Non–Equilibrium Radiative Cooling • Cooling is faster than recombination(tc<<tr) • Gas stays “over-ionized” • Modified ionization affects cooling rates:for over-ionized gas cooling is suppressed • Cooling rate depends on metallicityMore metals ⇒ faster cooling ⇒ further out of equilibrium ApJS 168, 213

  3. H He C N O Ne Mg Si S Fe Numerical Computation • Cooling from CIE at T>5x106K. • Follow time-dependent ionizationdxi/dt=… ~ • The energy equation (Cooling) dT/dt=… • Step 1: No Photoionization • dxi/dT independent of density • …But depends on metallicity ApJS 168, 213

  4. time Results: Ionization - Hydrogen Equilibrium Non-Equilibrium 100 10-1 10-2 104 105 106 104 105 106 Temperature (K) Temperature (K) Recombination Lag ApJS 168, 213

  5. Results: Ionization - Carbon Equilibrium Non-Equilibrium 100 10-1 10-2 104 105 106 104 105 106 Temperature (K) Temperature (K) ApJS 168, 213

  6. Results: CIE Cooling Metal Line Cooling Z = 2 Z = 1 Z = 10-1 Z = 10-2 Z = 10-3 10-21 10-22 H Lya Leq (erg cm3 s-1) cooling efficiency He Cooling 10-23 Bremsstrahlung 10-24 104 105 106 107 108 Temperature (K)

  7. Equilibrium Non-Equilibrium Results: Non-Equilibrium Cooling

  8. Fox et al. 2005 ApJ 630, 332 Turbulent Mixing Layers log ( CIV / OVI ) Shock Ionization Conductive Interfaces Cooling Flows log ( NV / OVI ) Local Metal-Ion Absorbers ApJS 168, 213

  9. High Velocity Metal Absorbers Fox et al. 2005 ApJ, 630, 332

  10. Time-Dependent Cooling - Summary • Equilibrium and Non-EquilibriumIonization States & Cooling Efficiencies ofH, He, C, N, O, Ne, Mg, Si, S, & Fe,For 104 < T < 108 Kand 10-3 < Z < 2 solar. • Isochoric / Isobaric – conditions & results. • Impact of Self Radiation. http://wise-obs.tau.ac.il/~orlyg/cooling/ ApJS 168, 213

  11. Step 2: Steady Flows of Cooling Gas • Integrated metal-ioncooling columnsin steady flows of cooling gas

  12. Post Shock Cooling Layers • Radiative transfer⇒ Photoionization, heating • Ionization: Auger • Precursor • Dynamics shock Pre-shock Post-shock gas T(x) <— upstream downstream —>

  13. Post-Shock Cooling Layers • Two extremes: • No B field - explicitly follow Rankine-Hugoniot continuity eqns: Mass Momentum Energy Nearly isobaric flow: P∞ = 4/3 P0 • Strong B field - isochoric evolution.

  14. High-T Radiative Zone Non-eq Cooling Zone The Photo- absorption Zone Post-Shock Cooling: Shock Structure Ts=5x106K Z=0.1 nH=0.1cm-3 (Photoionized) Radiative Precursor

  15. Post-Shock Cooling: Shock Structure Magnetic field Gas Metallicity Shock temperature

  16. Post-Shock Cooling: Emitted Radiation

  17. Post-Shock Cooling: Column Densities

  18. Gnat & Sternberg 2008 • Shock Structure, Profiles, Scaling Relations • Ion Fractions • Cooling and Heating • Integrated Column Densities • Columns in Precursors Thank you !

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