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Elliptical galaxies

Elliptical galaxies. M87. Fundamental Plane (Dressler et al. 87 ; Djorgovski & Davis 87;) Colour-mag nitude relation (Baum 59; Bower et al. 92; Kodama & Arimoto 97) Simple, red and dead… Why?. Hubble (1936): tuning fork diagram From www.smv.org/hastings/.

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Elliptical galaxies

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  1. Elliptical galaxies M87 • Fundamental Plane (Dressler et al. 87; Djorgovski & Davis 87;) • Colour-magnitude relation (Baum 59; Bower et al. 92; Kodama & Arimoto 97) • Simple, red and dead… Why? Hubble (1936): tuning fork diagram From www.smv.org/hastings/

  2. Abundant gas in ellipticals • Extended gas in 75% of nearby Es by SAURON (Sarzi et al. 2006) • Mass loss (30-90%) occurs in all stars • Mergers between gas-rich galaxies (Toomre & Toomre 1972) Red Supergiant V838 Monocerotis (STScI)

  3. Ellipticals in LCMD CMB (WMAP) LSS formation (T. Kimm & S.K.Yi) M. Steinmetz simulation

  4. Ellipticals in Hierarchical Merger Picture continue to show residual SF 500 cluster Es (Khochfar) What controls Residual SF? z

  5. Feedback • Why aren’t Es forming stars? • Preventing gas from cooling • SN feedback • BH feedback (Silk & Rees 98; di Matteo+ 05; Croton+ 06) • Still qualitative NGC4261 (STScI) Galactic Centre (Genzel)

  6. Galex-derived Star formation history of elliptical galaxies Are ellipticals really not forming stars at all? Sukyoung K. Yi (Yonsei) Kevin Schawinski, Sugata Kaviraj, Sadegh Khochfar (Oxford) and the GALEX Team

  7. GALEX-SDSS match And visual inspection gives ~103volume-limited close bright (>L*) early-types

  8. Searching for ellipticals 100 Mpc

  9. Ellipticals seen by GALEX Blue: UV Yellow: Optical Quiescent (QST) Recent star formation (RSF)

  10. CMR g – r Optical red sequence galaxies >30% formed stars in the last Gyr u – r NUV – r Yi et al. 2005, ApJ, 619, L111 Schawinski et al. 2006, ApJS; astro-ph/0601036

  11. Effect of density and mass Stellar mass Dynamical mass Local density Schawinski et al. 2006, ApJS; astro-ph/0601036

  12. Are recent mergers responsible for RSF? Brighter Es at z=0 had their latest merger more recently Last merger redshift Mr Kaviraj et al. 2006, ApJS; astro-ph/0602347

  13. Hierarchical merger models Last merger age (Gyr) Stellar mass Mv z dynamically younger but form their stars earlier DRY MERGER! Kaviraj et al. 2006, ApJS; astro-ph/0602347

  14. Recent SF – sigma relation Dynamical mass Stellar mass Schawinski et al. 2006, Nature, 744, 888

  15. The MBH-s relation (Silk & Rees 1998; King 2003) Tremaine et al. 2002

  16. “Critical” MBH – s relation MBH,Cµ s3.2 MBH,Cµ s3.6 Schawinski et al. 2006, Nature, 744, 888

  17. How do black holes grow? Schawinski et al. 2006, Nature, 744, 888

  18. Galaxy mergers Mdisk ~ 1011 Msun, MBH ~ 106 Msun x 10 ME ~ 1012 Msun, MBH ~ 109 Msun

  19. Summary • First UV Colour-magnitude relation • >30% of bright ETGs are forming stars at ~1% level (c.f. Rose 85; Worthey 94; Trager+ 2000; Bressan’s talk on FIR) • BH feedback may have some control over the RSF • Growth of black holes • Different types of mergers for large and small Es NASA/JPL-Caltech/T. Pyle.

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