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Radiation Pressure Supported Starburst Disks & AGN Fueling

Radiation Pressure Supported Starburst Disks & AGN Fueling. Todd Thompson UC Berkeley. With Eliot Quataert & Norm Murray. Evidence for Feedback: Winds. M82 (Subaru). Regulation of star formation on galactic scales. NGC 1569 (HST). Interactions, Mergers  Star Formation.

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Radiation Pressure Supported Starburst Disks & AGN Fueling

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  1. Radiation Pressure Supported Starburst Disks & AGN Fueling Todd Thompson UC Berkeley With Eliot Quataert & Norm Murray

  2. Evidence for Feedback: Winds M82 (Subaru)

  3. Regulation of star formation on galactic scales. NGC 1569 (HST)

  4. Interactions, Mergers  Star Formation NGC 4038/4039 (HST)

  5. ULIRGs Disk-like kinematics Star formation ~102-3 M/yr <n>~103-4 cm-3 ~100 pc scales Borne et al. (2000)

  6. The Standard Lore: Energy Deposition by Supernovae Collective effects of supernovae regulate the ISM and drive a hot thermal wind. McKee & Ostriker (1977) Chevalier & Clegg (1985) de Young & Heckman (1994) Efficiency may be very low in the high-density ISM of starburst galaxies. Strickland & Stevens (2000)

  7. A New Model: Radiation Pressure • Starburst or AGN photons are absorbed and scattered by dust grains (UV~100-1000 cm2 g-1). • Dust is collisionally coupled to gas: • Efficient feedback mechanism: couples to cold and dusty component, most of the mass. • Large-scale winds: Starbursts are near their “Eddington” limit (Murray, Quataert, Thompson 2005) • In ULIRGs, the ISM is optically thick to re-radiated IR on ~100 pc scales - radiative diffusion.

  8. Starburst Disks • Marginal stability, self-regulation: Toomre Q~1. • Vertical hydrostatic equilibrium: • Star formation: • Radiative diffusion: • Accretion ( or m): • Modified Schmidt Law: Sirko & Goodman (2003) Thompson, Quataert, & Murray (2005)

  9. The Rosseland Mean Opacity Dust sublimates! Tsub ~ 1000 K

  10. Bifurcation: Starburst vs. AGN At Rout, if then all of the gas is consumed in star formation on the scale Rout. Equivalently,

  11. Bifurcation: Starburst vs. AGN At Rout, if then the gas can propagate to small radii. It passes through the ``opacity gap’’ and fuels a bright central AGN.

  12. Bifurcation: Starburst vs. AGN

  13. Bifurcation: Starburst vs. AGN

  14. Very strong in the opacity gap yields vertical structure with h/r~1. Origin of nuclear obscuration in some AGN? Winds? NLR?

  15. Bifurcation: Starburst vs. AGN AGN Reprocessing?

  16. The Galactic Center: A Nuclear Starburst? The opacity gap generates a sharp peak in the star formation rate at ~0.1 pc for our galactic center. Levin & Beloborodov (2003) Genzel et al. (2003)

  17. Summary • Radiation pressure • can dominate feedback in the optically thick regions of starbursts. • couples to the cold dusty component, most of the mass. • can support the marginally-stable starburst disk. • Disk models (given ,  or m, Rout, MBH, fg) • predict starburst structure: • are in good agreement with observations (local & high-z ULIRGs). • fuel bright AGN without violating observational limits. • predict strong bifurcation between starburst dominated & AGN dominated solutions. • predict a nuclear starburst on ~1 pc scales (opacity gap). • predict qualitative change in the Schmidt Law: • Radiation pressure can drive large-scale mass-loaded winds: sets Faber-Jackson, M-, & maximum L of galaxies & BHs. Thompson, Quataert, Murray (2005) Murray, Quataert, & Thompson (2005)

  18. The End

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