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T. J. Cox

Feedback from AGN during Galaxy Mergers. T. J. Cox. Phil Hopkins Lars Hernquist + many others (the Hernquist Mafia). projected stellar distribution. projected gas distribution. Generic Outcome of Gas-Rich Galaxy Mergers.

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T. J. Cox

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  1. Feedback from AGN during Galaxy Mergers T. J. Cox Phil Hopkins Lars Hernquist + many others (the Hernquist Mafia)

  2. projected stellar distribution projected gas distribution

  3. Generic Outcome of Gas-Rich Galaxy Mergers • Tidal torques  large, rapid gas inflows (e.g., Barnes & Hernquist 1991) • Triggers starburst (e.g., Mihos & Hernquist 1996) • Feeds BH growth (e.g., Di Matteo et al. 2005) • BH Feedback disperses gas and reveals optical QSO • Merging stellar disks grow spheroid Requires: • Major (3:1) merger • supply of cold (i.e., rotationally supported) gas

  4. Proposed Chronology of a Galaxy Merger Cox et al. (2006)

  5. Types of Feedback During Gas-Rich Galaxy Mergers 1. Merger/Gravitational Feedback: collisional heating of gas owing to the interaction itself 2. Star Formation Feedback: energy/mass input from high-mass stars 3. QSO Feedback: energy input from high Eddington rate BH accretion. Note that this is separate from, but a necessary precursor to, “Radio-mode” feedback.

  6. Feedback from Star Formation and Black Holes • Basic energetics suggest that Efb,SN ~ Efb,BH • Timescale for energy injection is NOT equivalent SP < SF  The power can be very different • Location of energy injection is different: quasar feedback is deposited in the galactic center, star formation feedback is spread throughout the galactic disk

  7. Relative Feedback During “Active Phase” >5x more feedback energy from the BH

  8. Relative Feedback During “Active Phase” BH feedback during the “active phase” becomes increasingly dominant for systems of larger (total) mass

  9. BH Feedback During “Active Phase” BH feedback during the “active phase” regulates the mass of the black hole, and leads to the MBH- relation. Di Matteo et al. (2005), Springel et al. (2005)

  10. BH Feedback During “Active Phase” BH feedback during the “active phase” regulates the mass of the black hole, and leads to the MBH- relation. * The tight scatter in the MBH- * The BH fundamental plane (the BH mass is “fundamentally” related to the bulge binding energy) Hopkins et al. (2007)

  11. Which Feedback Influences the Structure of Merger Remnants? • Stellar feedback! • (it regulates the conversion of gas into stars and therefore determines the structure of the remnant galaxy) w/ BH w/o BH

  12. Color Evolution of Merger Remnants • Star formation quenched by black hole feedback, remnant reddens quickly Springel et al. (2004), Di Matteo et al. (2005) with black hole without black hole

  13. Color Evolution of Merger Remnants Do we really NEED BH feedback to produce red remnants? ** only for very gas-rich mergers moderate gas content (initially 40%, nearly all gas is consumed during merger) high gas content (initially 100%, a large amount left after merger)

  14. BH feedback likely regulates its own mass, but does it really need to be so violent (i.e., lead to a massive superwind)?

  15. A Typical Galaxy Merger (take 2) (on a larger scale) projected gas distribution Mass-weighted gas temperature

  16. The Influence on Gas in the Merger Remnant • Significant coronae of hot gas is produced • Mass and metals are ejected “explosion” doesn’t remove everything

  17. The Influence on Gas in the Merger Remnant • Emits X-rays (consistent with E scaling relations) • Cooling time and entropy are increased (Small systems may never cool and large systems are “primed and ready” for radio-mode feedback) but, SN-driven winds dominate the ejection of mass and metals

  18. Signatures of BH Feedback? • Outflows visible in absorption (Christy’s talk yesterday) • CO spectra (Appleton et al. 2002, Narayanan et al. 2006, Iono et al. 2007) • SZ (Evan’s talk?) Tremonti et al. (2006) Narayanan et al. (2006) NGC 6240 (Iono, et al., 2007, see also Appleton, et al. 2002 in NGC 985)

  19. Conclusions Star Formation Feedback: energy/mass input from high-mass stars * dominant source of feedback, regulates star formation & galaxy properties * very likely to dominate the integrated mass and metal ejection QSO Feedback: energy input from high Eddington rate BH accretion. Note that this is separate from, but a necessary precursor to, “Radio-mode” feedback. * very brief, but powerful * regulates black hole mass * contributes to heating of remaining gas * contributes to metal ejection * contributes to color evolution in massive, high gas content mergers

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